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recently , kinetic equations with fractional derivatives have attracted attention as a possible tool for the description of anomalous diffusion and relaxation phenomena , see , e.g. , recent review @xcite , semi - review papers @xcite,@xcite,@xcite and references on earlier studies therein . it was also recognized @xcite , @xcite that the fractional kinetic equations may be viewed as `` hydrodynamic '' ( that is , long - time and long - space ) limits of the ctrw ( continuous time random walk ) scheme @xcite , which was successfully applied to the description of anomalous diffusion phenomena in many areas , e.g. , turbulence @xcite , disordered medium @xcite , intermittent chaotic systems @xcite , etc . however , the kinetic equations have two advantages over a random walk approach : firstly , they allows one to explore various boundary conditions ( e.g. , reflecting and/or absorbing ) and , secondly , to study diffusion and/or relaxation phenomena in external fields , both possibilities are difficult to realize in the framework of ctrw ( we point , however , to the paper @xcite , in which a fractional kinetic equation was obtained from generalized ctrw ) . fractional kinetic equations can be divided into three classes : the first one , describing markovian processes , contains equations with fractional space or velocity derivatives and the first time derivative , the second one , describing non - markovian processes , contains equations with fractional time derivative , and the third class , naturally , contains both fractional space and time derivatives , as well . in this paper we deal with a one - dimensional kinetic equation belonging to the first class , namely , with the fractional symmetric einstein - smoluchowski equation ( fsese ) , which , from one hand , is a natural generalization of the diffusion - like equation with the symmetric fractional space derivative @xcite,@xcite and , from the other hand , is a markovian generalization of the einstein - smoluchowski kinetic equation , which describes a motion of a particle subjected to a white gaussian noise in a strong friction limit , see , e.g. , @xcite . from this point of view , the fsese describes a motion of a particle subjected to a white lvy noise , also in a strong friction limit @xcite . in dimensionless units the one - dimensional fsese has the form @xmath4 where @xmath5 is the probability density function , @xmath6 is the deterministic external force , @xmath0 is the lvy index , @xmath7 , @xmath8 is the symmetric fractional space derivative [ 2 , 11 ] , which is defined , for a sufficiently well - behaved function @xmath9 through its fourier - transform @xmath10 as @xmath11 or in terms of the riemann - liouville derivatives as @xmath12 , \tag{1.3}\ ] ] where @xmath13 , @xmath14 for @xmath15 . for @xmath16@xmath17 @xmath18 . the derivatives ( 1.4 ) and ( 1.5 ) are characterized in their fourier representation by @xmath19 where @xmath20 . one can easily recover eq . ( 1.2 ) by combining eq . ( 1.3 ) with eq . ( 1.6 ) . a detailed theory of the riemann - liouville and other forms of fractional derivatives is presented in @xcite . the solution of eq . ( 1.1 ) in the force - free case , @xmath21 , is known to be a probability density function ( pdf ) for an @xmath22 stable symmetric process . the solution of eq . ( 1.1 ) was also obtained for the constant field , @xmath23 on the whole axis , @xmath24 , and for a linear lvy oscillator @xcite . as far as the authors know , eq . ( 1.1 ) was not considered for a more complicated potential fields . in the present paper we study the equilibrium solution of the fsese for non - linear lvy oscillator with the potential energy @xmath25 the models with the potential energy ( 1.7 ) play an important role in the theory of dynamical chaos @xcite and in the theory of brownian motion in an open auto - oscillation systems @xcite , and have various applications @xcite . one may expect that the models of non - linear lvy oscillator will also possess an important place in the theory of the systems influenced by non - gaussian lvy noises and obeying fractional kinetic equations . for our purposes we pass to the equation for the characteristic function @xmath26 , @xmath27 for the equilibrium state @xmath26 obeys the equation , which follows from eqs . ( 1.1 ) and ( 1.7 ) : @xmath28 where the index `` eq . '' denotes equilibrium solution . below in the paper we omit subscript `` eq '' for brevity . the characteristic function obeys the following conditions . @xmath29where the asterisk implies complex conjugate . the first equality is a consequence of the khintchine theorem about reality of the characteristic function for the symmetric pdf , whereas the second equality is the consequence of the bochner - khintchine theorem about positive definiteness of the characteristic function . in fact , one can see that the solution of eq . ( 1.9 ) obeys the condition 1 . the boundary conditions for @xmath30 are as follows : @xmath31 the first property stems from normalization of the pdf , @xmath32 the second property stems from the existence of the pdf . as to the third property , we remind that the integer moments of the pdf ( if exist ) are connected with the derivatives of the characteristic function at @xmath33 as @xmath34 the third property is the consequence of this theorem : @xmath35 because the pdf is a symmetric function , and hence , all odd moments are equal zero . the last equality is valid for those odd @xmath36 , for which the @xmath36 - th moments of the pdf exist . to make results more transparent , the rest part of the paper will be organized as follows . in sect.2 we recall the results for non - linear brownian oscillator , @xmath37 . in sect.3 we get an equilibrium solution for an non - linear cauchy oscillator , @xmath38 . in sect.4 , which is the main one , we present analytical and numerical results on equilibrium solutions for non - linear lvy oscillators with the lvy indexes lying between 1 and 2 , brownian and cauchy oscillators being their particular cases . finally , in sect.5 we present the discussion and summarize the results . some subsidiary studies , which support the results obtained in sec.4 , are presented in appendix a. an integral which is necessary for estimating asymptotics of the pdf is calculated in appendix b. in this section , which is presented here mainly for the methodical purposes , we remind the equilibrium solution for non - linear brownian oscillator , @xmath37 . it is well - known , that in this case there is no need to pass to the equation ( 1.9 ) ; on the contrary , the starting point is the stationary equation , which follows from eqs . ( 1.1 ) and ( 1.7 ) : @xmath39 it has the boltzmann solution @xmath40 where the constant @xmath41 is determined from normalization condition . for a non - linear quartic brownian oscillator @xmath42 we are also in position to get the characteristic function by making fourier transform of equilibrium solution ( 2.2 ) , ( 2.3 ) and , then expanding @xmath43 into the power series and integrating over @xmath44 each term separately : @xmath45 where @xmath46 in sect .. 4 we show that this solution is a particular case of that for a non - linear lvy oscillator . for this case we start from eq . ( 1.9 ) with @xmath38 . the solution is @xmath47 .this solution can be expanded into the power series of @xmath48 as @xmath49 where @xmath50 . \tag{3.3}\ ] ] making an inverse fourier transform of eq . ( 3.1 ) , we get equilibrium pdf for the cauchy oscillator , @xmath51 clearly , @xmath52 and @xmath53 , so @xmath54 is a pdf . equation ( 3.4 ) clearly indicates strongly non - boltzmann character of the equilibrium pdf for non - linear cauchy oscillator . in fig.1 both pdfs for brownian and cauchy oscillators are shown in a linear ( at the top ) and in a semi - logarithmic ( at the bottom ) scales . the two important distinctive features of the equilibrium pdf for the cauchy oscillator are ( i ) the bimodality , and ( ii ) power law asymptotic at @xmath55 . the latter property is clearly visualized in a linear scale , whereas the former is better shown in a semi - logarithmic scale . it appears that both features are inherent not only to a non - linear cauchy oscillator , but also to equilibrium pdfs of non - linear lvy oscillators with the lvy indexes @xmath0 , such that @xmath56 . in the next section we get the solution for an arbitrary @xmath57between 1 and 2 and clearly demonstrate this fact . we turn to the solution of eq . ( 1.9 ) with the boundary conditions ( 1.10 ) . one can convince himself that the solution of eq . ( 1.9 ) with the first and the third conditions from eqs . ( 1.10 ) being taken into account can be represented as @xmath59 where @xmath60 @xmath61 and the coefficients @xmath62 are obtained by inserting eqs . ( 4.2 ) and ( 4.3 ) into eq . ( 1.9 ) and equating the terms of the same powers of @xmath63 in the right - and left - hand sides : @xmath64 @xmath65 @xmath66 obviously , the @xmath67 as well as @xmath68 tend to zero extremely fast . the terms @xmath69 and @xmath70 are , in fact , two independent particular solutions of eq . ( 1.9 ) . since the condition at the infinity from eq . ( 1.10 ) has not been employed yet , the general solution thus depends on an arbitrary constant @xmath71 . we define it numerically by demanding @xmath72 that is , @xmath73 our numerical simulations show that with @xmath63 increasing the value of @xmath71 rapidly reaches the constant value , which , of course , depends on @xmath0 . further increase of @xmath63 allows us to get @xmath71 with higher accuracy , that is , with more significant digits . it is also worthwhile to note that the radius @xmath74 of convergence for both power sets in numerator and denominator of eq . ( 4.7 ) is infinite . this fact can be easily shown with the help of the cauchy - hadamard theorem ( see , e.g. , @xcite , p. 300 ) , according to which , e.g. , for @xmath69 @xmath75 where the bar denotes the largest limit for the sequence @xmath76 in fig . 2 the obtained solution for @xmath26 is shown in a linear ( at the top ) and in a semi - logarithmic ( in the bottom ) scales , @xmath77 . one can see an oscillatory character of the solution at large @xmath63 ; this property can not be visualized directly from the power series expansion . therefore , we also get a large @xmath78asymptotic of the solution to eq . ( 1.9 ) . the derivation of it is presented in appendix a in detail . there we demonstrate that ( i ) the asymptotics has an oscillatory character and an exponentially decreasing amplitude , and ( ii ) the period of oscillations coincide with high accuracy with that obtained numerically from power series expansion , see fig.2 . thus , with the help of appendix a we have an independent evidence of the correctness of our procedure and of the solution presented in this section above . another evidence of the correctness of the obtained results stems from the comparison of the general expressions ( 4.1 ) - ( 4.5 ) with those for the two particular cases @xmath37 and 1 , presented in sect .. 2 , see eqs . ( 2.4 ) , ( 2.5 ) , and in sect .. 3 , see eqs . ( 3.2 ) , ( 3.3 ) , respectively . indeed , let us consider brownian oscillator at first . by comparing expansion ( 4.1 ) at = 2 with that given by eq . ( 2.4 ) one can see that the odd coefficients @xmath79 and @xmath80 given by eq . ( 2.5 ) have the same recurrent relation as the coefficients @xmath81 and @xmath82 given by eq . ( 4.4 ) have , whereas the even coefficients @xmath83 and @xmath84 given by eq . ( 2.5 ) have the same recurrent relation as the coefficients @xmath85 and @xmath86 given by eq . ( 4.5 ) have . now , let us compare general expressions with those for the cauchy oscillator . by comparing expansion ( 4.1 ) at @xmath38 with that given by eq . ( 3.2 ) one can see that the coefficients @xmath87 and @xmath88 in eq . ( 3.3 ) obey recurrent relation between the coefficients @xmath81 and @xmath82 , see eq . ( 4.4 ) , whereas the coefficients @xmath89 and @xmath90 obey recurrent relation for the coefficients @xmath85 and @xmath86 , see eq . ( 4.5 ) . at last , @xmath91 , which is also in agreement with general expansion , if we set @xmath38 in eq . ( 4.1 ) . thus , we may conclude that the general expansion ( 4.1 ) - ( 4.5 ) is in agreement with the particular cases of brownian and cauchy oscillators . however , we have to take in mind that for the brownian and cauchy cases we are able to evaluate coefficient @xmath92 analytically . on the contrary , for an arbitrary we have to estimate this coefficient numerically with the use of eq . ( 4.7 ) . of course , the results of numerical and analytical estimates coincide for @xmath38 and 2 . now we consider two important properties which have been already discussed for the particular case of the cauchy oscillator in sect .. 3 , namely , power law tails and bimodality . consider power law tails at @xmath93 at first . these asymptotics are determined by the first non - analytical term in the power series expansion ( 4.1 ) , that is , the term @xmath94 . by making an inverse fourier transform of this term , we get @xmath95 where @xmath96 ^{-1 } $ ] . this integral is calculated by passing to the complex plane , the detailed derivation is presented in appendix b. the result is @xmath97 it follows from eq . ( 4.8 ) that the equilibrium pdf has a power law tail , @xmath98 , and , thus the integer moments of the order greater than 3 diverge . this behavior is strikingly different from that of a non - linear brownian oscillator . the `` long tails '' can be explained qualitatively , if we turn to the langevin description of the lvy oscillator , the langevin approach relevant to the fsese [ 13 ] implies that the non - linear overdamped oscillator is influenced by white lvy noise @xmath99 , whose pdf behaves as @xmath100@xmath101at @xmath100@xmath102 . these long tails imply that the large absolute values of the noise occur frequently , which , in turn , lead to large increments of the coordinate . however , it is also clear that the pdf of the coordinate @xmath44 must fall off more rapidly at @xmath103 than the pdf of the noise @xmath104 , because of the presence of the potential well , which prevents @xmath44 from escaping rather far from the origin . in fig . 3 equilibrium pdf is shown by solid lines in a linear ( at the top ) and semi - logarithmic ( at the bottom ) scales . the pdf is obtained by an inverse fourier transform of the characteristic function shown in fig . 2 , @xmath105 . the dashed lines indicate asymptotic ( 4.9 ) . one can see , especially from the semi - logarithmic plot , that the asymptotics is a good approximation beginning from @xmath63 equal nearly 2 . in this figure the second important property , namely , bimodality is clearly seen in a linear scale . in fig . 4 the profiles of equilibrium pdfs ( obtained by an inverse fourier transform of corresponding power series in @xmath63 -space ) are shown for the different lvy indexes from @xmath38 at the top of the figure till @xmath37 at the bottom . it is seen that the bimodality is most strongly expressed for @xmath38 . with the lvy index increasing the bimodal profile `` smooths '' and , finally , it turns to a unimodal one at @xmath37 , that is , for the boltzmann distribution . we also perform numerical simulation based on numerical solution of the langevin equation @xmath106 where @xmath107is a white gaussian noise or a white lvy noise , whose generator is described in detail in our previous papers devoted to the studies of self - affine properties of ordinary and fractional lvy motions @xcite,@xcite . a discussion on equivalency of the description of a stochastic system with the help of the langevin equation ( 21 ) and fractional kinetic equation ( 1 ) is presented in ref . @xcite ; for the brownian motion this problem is discussed , e.g. , in ref . @xcite , in detail . in fig.5 the results of numerical modelling are presented for the brownian oscillator , @xmath37 ( above ) and the lvy oscillator , @xmath108 ( below ) . at the left the trajectories @xmath109 are presented , where @xmath110 is the number of time steps in numerical modeling , @xmath111 is the length of a single step , @xmath112 . the result of numerical solution of the langevin equation must not depend on @xmath113 ; for the brownian oscillator this requirement is fulfilled at @xmath114 , whereas for the lvy oscillator @xmath115 . we also studied the time - dependence of the second moments and fix when the moments become constant , thus indicating equilibrium state . from the left figures a clear difference between trajectories of brownian ( above ) and lvy ( below ) oscillators is seen : there are large `` jumps '' on the figure below , which are due to existence of large `` pushes '' from an external lvy noise @xmath116or , equivalently , due to power law asymptotic of the pdf of the lvy noise @xmath104 . now we turn to the right figures . the designations are as follows . thick solid line 1 and dotted line 2 show the potential well and its curvature , respectively , in conventional units . thin solid line 3 shows the boltzmann distribution ( 2.2 ) . the black points depict the pdfs obtained in numerical simulations by statistical averaging over 50 trajectories each of 20.000 steps . finally , the power law asymptotic ( 4.9 ) are depicted by a thin solid line 4 . it is seen from the figure above that the pdf obtained in numerical simulations agrees quantitatively with the boltzmann pdf , whereas the figure below demonstrates drastic difference between the boltzmann pdf and numerical pdf . the latter has long power asymptotic , which start far away from the maximum of the potential well curvature , and whose exponent is close to that obtained theoretically . this conclusion is confirmed by the results of numerical modeling for the lvy oscillators with different lvy indexes , see fig . 6 . in this figure the black points depict the values @xmath117of the exponents of the asymptotic @xmath118- of the equilibrium pdfs for @xmath119 and 1.9 . the values @xmath117of are estimated as a tangent of a slope angle of a rectilinear asymptotic in a double logarithmic scale . the statistical averaging is over 50 trajectories , each consisting of 20.000 time steps , @xmath120 . dotted line depicts theoretical dependence @xmath121 of the asymptotic exponent versus @xmath0 . the results of numerical simulations coincide with analytical estimates within the error limits . in fig . 7 the results of numerical modeling are presented in more detail for small values of @xmath44 , when power law asymptotic is inadequate . similarly to fig . 5 , thick solid line 1 and dotted line 2 show the potential well and its curvature , respectively . solid line 3 indicates pdf obtained by an inverse fourier transform of the power series in @xmath78space . the black points depict pdf obtained in numerical simulations by statistical averaging over 20 trajectories , each of @xmath122 steps . the lvy index is 1.2 . it is clearly seen that both pdfs are in qualitative agreement and the both are bimodal . therefore , from figs . 5 - 7 we may conclude that the results of simulations based on numerical solution of the langevin equation confirm qualitatively and even quantitatively the results based on analytical solution of eq . ( 1.9 ) for the characteristic function . in this paper we study , both analytically and numerically , the properties of equilibrium pdf of a non - linear ( @xmath2 ) lvy oscillator , that is , the oscillator which is subjected to a white lvy noise obeying a lvy stable probability law . we restrict ourselves to the case of the lvy indexes such that @xmath123 . it is known that the lvy stable distributions ( as the gaussian one , which corresponds to @xmath57equal 2 ) appear in problems , whose result is determined by the sum of a great number of independent identical factors . since the brownian oscillator is subjected to a white gaussian noise , the lvy oscillator is a natural generalization of a brownian one . for the analytical studies the starting equation is the so - called fractional symmetric einstein - smoluchowski equation , which contains fractional symmetric space derivative and is a natural generalization of the kinetic einstein - smoluchowski equation used in the theory of brownian motion . we get analytically the characteristic function of the equilibrium pdf in the form of a power series . its inverse fourier transform , realized numerically , allows us to obtain the pdf . the two main distinctive features of the equilibrium pdfs for non - linear lvy oscillator with @xmath124 are ( i ) the power law asymptotic at large x , and ( ii ) bimodality . both features imply that the pdfs for non - linear lvy oscillators are strikingly different from boltzmann distribution , which is equilibrium pdf for the brownian oscillator . the bimodal profile of the equilibrium pdf is clearly visualized after an inverse fourier transform of the power series expansion for the characteristic function . two maxima are most strongly expressed for @xmath126 ( cauchy oscillator ) . with the lvy index increasing the profile `` smooths '' and at @xmath37 ( brownian oscillator ) turns to profile with a single maximum . second : the particular case of the cauchy oscillator ( @xmath38 ) admits complete analytical study , which allows us also to check the agreement between power series and to demonstrate power law asymptotics and bimodality of the pdf . third : we obtain the solution of the equation for the characteristic function at large values of the argument @xmath63 and show that the periods of oscillations of this asymptotic solution in @xmath78space coincide with high accuracy with those obtained from the power series . we also perform numerical simulation based on numerical solution of the langevin equation for a non - linear oscillator subjected to a white gaussian noise . the equilibrium pdfs obtained in simulation show quantitative agreement with pdfs obtained analytically . at the end we note that the general case of a non - linear lvy oscillator ( @xmath127 . ) can be treated in a similar way . in particular , it can be shown that in this case the power law asymptotics have an exponent @xmath128 @xmath129 . we also make a comparison between the period of the asymptotics ( a.4 ) and the period of oscillations of the solution ( 4.1 ) - ( 4.7 ) . firstly , we are able to get with high accuracy the values @xmath150 , at which the solution given by eqs . ( 4.1 ) - ( 4.7 ) is equal zero , see also fig . , we insert @xmath151 into the cosine in eq . ( a.4 ) and estimate it is seen , that @xmath153 can serve as a measure of difference between zeros of @xmath26 estimated from eqs . ( 4.1 ) - ( 4.7 ) and those estimated from eq . ( a.4 ) . for example , for the characteristic function with @xmath77 , which is shown in fig . 2 , we get @xmath154 these results demonstrate the smallness of @xmath153 and serve as one more confirmation of the correctness of our approach . in order to evaluate @xmath158 , we pass to the complex plane . since the integral over the closed contour shown in fig . 8 is equal zero , we get @xmath159 and @xmath160 with the use of eqs . ( 4.8 ) and ( b.5 ) we get power law asymptotics of the equilibrium pdf , see eq . ( 4.9 ) . equilibrium characteristic function for non - linear lvy oscillator in the linear ( above ) and semi - logarithmic ( below ) scales , @xmath105 . characteristic function ( 4.1 ) is evaluated by the use of eqs . ( 4.1 ) - ( 4.7 ) . equilibrium pdf and its asymptotics in the linear ( above ) and semi - logarithmic ( below ) scales , @xmath105 . the pdf obtained by inverse fourier transform of a power series ( 4.1 ) is indicated by solid lines . dashed lines indicate power law asymptotics ( 4.9 ) . comparison of analytical estimates with the results of numerical simulation based on numerical integration of the langevin equations for the brownian ( above ) and the lvy ( below ) oscillators . the lvy index is 1.1 . at the left : typical trajectories , @xmath161 is the number of steps . at the right the semi - logarithmic scale is used . the designations are as follows . thick solid line 1 and dotted line 2 show the potential well and its curvature , respectively , in conventional units . boltzmann distribution is indicated by solid line 3 , the pdf obtained in numerical simulations is shown by black points , solid line 4 shows the power law asymptotics ( 4.9 ) . comparison of analytical estimates with the results of numerical simulation based on numerical integration of the langevin equations . the black points indicate the slope @xmath162of the power law asymptotics of equilibrium pdfs obtained in numerical simulations for different lvy indexes . dotted line depicts theoretical value @xmath121 . comparison of analytical estimates with the results of numerical simulation based on numerical integration of the langevin equations . the lvy index is 1.2 . thick solid line 1 and dotted line 2 show the potential well and its curvature , respectively . solid line 3 indicates pdf obtained by inverse fourier transform from eq . black points indicate pdf obtained in numerical simulation .

we study , both analytically and by numerical modeling the equilibrium probability density function for an non - linear lvy oscillator with the lvy index @xmath0 , @xmath1 , and the potential energy @xmath2 . in particular , we show that the equilibrium pdf is bimodal and has power law asymptotics with the exponent @xmath3 . _ pacs _ : 05.10 gg , 05.40 fb _ keywords _ : fractional kinetic equation , non - linear oscillator , equilibrium probability density function .

On Friday night, President Donald Trump had some pointed comments towards the NFL when it comes to players protesting during the national anthem. “Wouldn’t you love to see one of these NFL owners, when somebody disrespects our flag, to say, ‘Get that son of a bitch off the field right now. Out. He’s fired. He’s fired’,” the president said at a rally in Alabama. Speaking Monday morning on Kirk & Callahan, Tom Brady, who linked arms with some of his teammates to show unity during the anthem on Sunday, said he disagreed with what the president said. “Yeah, I certainly disagree with what he said. I thought it was just divisive," Brady said. "Like I said, I just want to support my teammates. I am never one to say, ‘Oh, that is wrong. That is right.’ I do believe in what I believe in. I believe in bringing people together and respect and love and trust. Those are the values that my parents instilled in me. That is how I try and live every day. I have been blessed to be in locker rooms with guys all over the United States over the course of my career. Some of my great friends are from Florida, Virginia, New York, Montana, Colorado, Texas. The one thing about football is it brings so many guys together — guys you would never have the opportunity to be around. Whether it was in college, and all the way into the pros. We’re all different, we’re all unique. That is what makes us all special.” The quarterback reiterated his comments from after the game about why he linked arms with Phillip Dorsett and others. It was about the love and support he has for his teammates. He also had an Instagram post before the game showing support for NFL players. “Yeah, I have a lot of respect for the players around the league and for obviously my teammates," he said. "I said after the game I just love my teammates and it takes a lot to play in the NFL. The guys that have played in the past really paved the way for us and what I thought in that post is that is what makes this game great - players, coaches that come together for one goal, to try and go out there and do the best we can do every week. It certainly is not an easy game. It’s intense. You sacrifice a lot. We’re all making a choice to do that. There’s no - we love doing that and I love being out there being out there playing with my teammates. It’s a great blessing in my life. That’s kind of how I felt.” Added Brady: "Hopefully it brings everyone together. I think that is what unity and love — like I said after the game, those are the things that concern me. When you’re in a locker room full of 53 players, you’re working to a common goal. You support the guys that you play with and you support your coaches, coaches support you. You just do the best you can do. You’re navigating through life. These things aren’t easy. Everyone deals with different challenges in their life and you respect everyone’s opinions and views. You don’t have to agree with everything. It’s hard to agree with your own wife on everything from day-to-day. I have so much respect for my teammates and what we’re trying to accomplish. Hopefully we can keep marching toward this end of the season, keep making improvements, get better and win more football games.” Brady said he heard the boo's during and after the anthem from some in the crowd and said people can do what they want to do. “Yeah, I did," he said. "No, I think everyone has the right to do whatever they want to do. If you don’t agree, that is fine. You can voice your disagreement, I think that is great. It’s part of our democracy. As long as it is done in a peaceful, respectful way, that is what our country has been all about.” ||||| Follow KDKA-TV: Facebook | Twitter PITTSBURGH (KDKA) – Pittsburgh Steelers fans are taking to social media to show how upset they are that the team stayed inside during the national anthem. Fans have posted numerous videos on social media of themselves burning their Steelers gear. “I’m a lifelong Steelers fan, not anymore. Not a fan of you, the NFL, any of it,” says Jim Heaney on YouTube. Heaney posted the video of himself setting all of his Steelers gear on fire following the team’s decision to decide to stay inside the locker room/tunnel during the national anthem. “And I hope all your ignorance burns too,” Heaney says as he throws his Steelers gear on the fire. Heaney ends his video by saying, “there you go, goodbye Pittsburgh Steelers, burn in hell, Semper Fi.” In another video posted to YouTube, Robert Williams of Texas posted a video of himself burning hundreds of dollars in Steelers gear. “We have morals in this country. We stand for this country. My great uncle’s bones are lying in the bottom of Pearl Harbor. For this country, for the flag, for your freedom to play in the NFL and to say whatever you want to say. But you do not disrespect the flag and the country and the Constitution. So watch this stuff burn,” Williams says. I have been a Steelers fan since 1966, but no more. pic.twitter.com/9W4oMl1EhF — Starving1 (@ArvinGibbs) September 24, 2017 In a video posted to Twitter, and shared more than 15,000 times, Arvin Gibbs is seen on video burning a Steelers sweatshirt and hat, while holding an American flag. “Super Bowl right? As if I care, what I care about is this country, what I care about is freedom, and it’s all about those stars and stripes,” Williams says. RELATED: Steelers lineman Alejandro Villanueva Only Player To Stand For National Anthem, Jersey Sales Skyrocket “Never again will waste one minute of my life following the NFL or the Pittsburgh Steelers,” another YouTube video user says. “I am no longer am a Steelers fan or of anyone that will not stand for our anthem no matter your political views or color of your skin. I hope your sport goes up in flames like my shirt did,” says Christos Kallas. “Today after 30 years of loving the Pittsburgh Steelers I’m going burn my Steelers jersey . They have taken a great American sport that people use to forget there problems with and turned it into a political circus that disrespects our Country and our Military that gave there lives for your freedom,” posted YouTube user Michael Hesson. The protest was also the main topic of discussion on 93-7 The Fan Monday morning. “They announced that the Steelers previously weren’t going to come on the field for the national anthem. When they came on the field, the whole bar booed, the whole single bar,” said one caller. “I actually got up and left I was so upset.” Head coach Mike Tomlin, who stood on the sideline without his team, said the team made the decision during a meeting on Saturday. Lisa Washington’s Report: Some fans believe the Steelers’ organization will suffer because of the action. “I don’t think the Steelers are going take a long-term hit,” said another caller. “I think it will be temporary hit, maybe the next couple of games. I think people will talk about it, but if they start winning, if they start producing, it will blow over, because as we know in this country, winning cures all.” Some fans said they supported Alejandro Villanueva, Steelers offensive tackle and a former U.S. Army Ranger. He stood near the tunnel Sunday during the National Anthem, with his hand over his heart. His teammates stood behind him. “Al Villanueva, he knows the real meaning of teamwork because he led men in combat,” said one caller. “He’s probably saying to himself, what am I doing with this group of people?” Another caller noted, “This protest is not about black and white. It’s not about disrespecting the flag. And whether you agree or not, as a veteran of 17 years and two branches of the U.S. Military, I support what the players want to do.” Lynne Hayes-Freeland’s report: A few others, however, felt that the protests were starting to overshadow the core issue. “There are some issues that fundamentally need to be addressed,” DeWitt Walton, of the Hill District, said. “That there is racism. That there is injustice.” “Think about Muhammad Ali, Jesse Owens, the Negro Baseball League, and all of those things. They made those issues political as well, so I don’t buy that,” Dewayne Fulton, of Plum, said. “Again, the platforms that are given to you, if you have the power to make change in a positive way, you should use them.” Steelers linebacker Arthur Moats tells the “KDKA Morning News” he and his wife will gladly collect unwanted Steelers merchandise and give it to veterans that want it. “We’ve never had an issue with veterans and the numerous veterans that I’ve talked to all agree with us and they understand what the whole purpose of Sunday was… So, we’re like hey if you guys feel that strong about what we did and you truly feel you can’t be a Steeler fan anymore…go ahead, send us your stuff, we’ll go ahead and distribute to people who really want to be Steeler fans and who may not be able to afford some of the new gear and we’ll gladly pass it on to them,” said Moats. Moats says that the Steelers would never do anything to disrespect veterans. “Our thing going forward is how a person can still make these reactions and comments that we’re…anti-military when it’s been spoken [about] from one of our veterans, one of our veterans who is a teammate?” ||||| Media playback is unsupported on your device Media caption Why America's sports stars are taking a knee President Donald Trump's swipes at the National Football League players' protests were nestled in the middle of a nearly hour-and-half-long speech at a rally in Alabama. The crowd cheered enthusiastically - as they did for his taunts directed at Hillary Clinton, Kim Jong-Un and Senator John McCain, and boasts about his election victory and the beautiful, see-through wall he will build along the US-Mexico border. It was the NFL comments that gained traction, however, sparking outrage and condemnation from sports stars and franchise owners. NFL games on Sunday were the setting for dozens of player protests of various kinds. Meanwhile the president, as is his habit when challenged, leaned in to the controversy, firing off a flurry of tweets on the topic. "NFL attendance and ratings are WAY DOWN," read one presidential missive. "Boring games yes, but many stay away because they love our country. League should back US." The president seems almost to take pleasure in fanning the flames of controversy, going so far as to call for a boycott of the US's most popular sports league. But why? Here are a few possibilities. It's strategic Things have been rough for the president recently. Once again it appears that Congress is going to be unable to repeal and replace Obamacare health insurance reforms, despite the president's assurances that doing so would be "easy". That transparent wall he touted? It currently seems more likely that the president will strike a deal with Democrats to enshrine protections for undocumented immigrants who entered the US as children - a move anathema to portions of his conservative base - than get funding from Congress to build the border barrier. The candidate the president was in Alabama to boost, Senator Luther Strange, could go down to defeat on Tuesday, representing an embarrassing rebuke to the president from his most loyal supporters. His approval ratings may be climbing, but there's been a lot of bad news recently - and more could be coming. So what better way to change the subject than to restart a highly charged cultural debate about the appropriateness of political protests against the national anthem; one that allows the president, much to the delight of his base, to sing the praises of the US military and wrap himself tightly in the red, white and blue? Image copyright Getty Images It's personal Before Donald Trump was a politician or even a reality television star, he was a professional football owner. The league was the star-crossed USFL in the mid-1980s, and the team was the New Jersey Generals. Then real-estate magnate Trump bought the team in 1984 and helped encourage the USFL, which was then playing its games in the spring, to move to the autumn, where it would go head-to-head with the NFL. The NFL crushed the fledgling USFL. Mr Trump unsuccessfully tried to sue the larger league for antitrust violations, many teams went bankrupt, and the USFL eventually folded. Fast forward to 2014, and Mr Trump had another run-in with the NFL, when he tried to buy the Buffalo Bills team. He was outbid by an energy-sector billionaire and - in a move that should now be quite familiar - took to Twitter to vent his anger. "Even though I refused to pay a ridiculous price for the Buffalo Bills, I would have produced a winner," he tweeted. "Now that won't happen." He also called NFL games "boring" and "too soft", adding that he was glad the deal didn't go through. In other words, Mr Trump has a longstanding grudge against the NFL - and if there's one thing we know about the president, it's that he likes to settle old scores. Image copyright Getty Images Image caption Some of the Detroit Lions dropped to their knee on Sunday It's impulsive When talking about Donald Trump's actions, it's often tempting to find order where only chaos exists; to ascribe grand schemes when there's an easier, simpler explanation. The president isn't playing three-dimensional chess and devising plans within plans. With his NFL outburst, the president could once again be reacting to events, not directing them. On Friday night he gave a long speech filled with everything that was bubbling through his mind at that particular moment. If the media had focused on his dismissal of the Russia investigation as a hoax or his insistence that winning the popular vote in the presidential election last year would have been easy if he had tried, then that's what the president would have spent the weekend tweeting about. Instead, here we are, on day four of a furore over players kneeling and flags flying, free speech protections and employee obligations. If there is no grand strategy, then modern American politics is like a spinning top. There's no way of telling where it's going to go next. ||||| Tweet with a location You can add location information to your Tweets, such as your city or precise location, from the web and via third-party applications. You always have the option to delete your Tweet location history. Learn more ||||| Regarding Trump’s fire-the-NFL-protesters line last night that Teddy noted, it is a classic example of Trump’s, at times, gut-level political savvy. This kind of thing is why he’s president. He takes a commonly held sentiment — most people don’t like the NFL protests — and states it in an inflammatory way guaranteed to get everyone’s attention and generate outrage among his critics. When those critics lash back at him, Trump is put in the position of getting attacked for a fairly commonsensical view. Of course, NFL owners firing players on the spot for protesting isn’t necessarily common sense, but this is where “seriously, not literally” comes in. Since everyone knows that owners aren’t going to do this, Trump’s statement registers for his supporters merely as forceful opposition to the protests, not as a specific plan of action. His advocacy for a Mexico-funded border wall and for the Muslim ban played in a roughly similar way (although The Wall was taken more literally, hence Trump’s exertions to make a colorable case that it is being built). Finally, when Trump is criticized and doesn’t back down it is taken by his supporters as a sign of strength. If a political consultant came up with this strategy, he’d deserve a huge raise. But it’s just Trump himself operating on instinct. ||||| A local restaurant owner says he's taking a stand after recent friction between the NFL, its players and President Trump, over the national anthem. On Sunday, as NFL stars across the country took to one knee during the national anthem in response to inflammatory comments from President Trump, Palmetto Restaurant and Ale House owner David McCraw was planning something of his own. "NFL will never be played at Palmetto Alehouse until all players pay respect to our flag and our country!!!" said the business owner to FOX Carolina, calling the players both entitled and arrogant individuals who use their position for advancement. McCraw, an ex-military member, says he found the actions of NFL players protesting the national anthem by kneeling, disrespectful. He said he feels that athletes and people who've attained celebrity status should not be telling people what or what not to do because they don't share the same struggles as people who live normal lives. "I do not support anyone that thinks that our country or our flag is not worth standing for," he explained. Instead, he believes fans should walk out of the stadium altogether. When FOX spoke with McCraw on Sunday, he said though he didn't always agree with President Trump's views, he did agree with the president's statement that NFL players who kneeled during the national anthem at games, should be fired. NFL Sunday kicks off amid beef between players, Trump "Our president is our president, but I don't stand in unity with everything he says," said the restaurant owner. "This is a country of one people and we need to stand for our flag." "There are issues in this country that need to be addressed, but disrespecting our flag and our country is not the way to do it," said McCraw. He thinks there's a better way to affect change. And as far as how the restaurant owner's decision will affect business, McCraw says he's not losing any sleep over it. "It's no concern for me," said McCraw. "I'm an ex-military guy. My whole concept is about being local and supporting the community. It is not about supporting a concept that is disrespectful to our flag or our country, and I don't think the people that come to my bar will feel that this is disrespectful to them." “We don’t need to be told by athletes or celebrities how to think," McCraw added on Monday. He hopes customers who are NFL fans will respect his decision and promises there will still be sports on every TV screen, just not NFL games at the moment. MORE NEWS: #Blu4Ru: Middle school student released from hospital after brain tumor removed, father says Copyright 2017 FOX Carolina (Meredith Corporation). All rights reserved. ||||| Pittsburgh Steelers offensive lineman Alejandro Villanueva became the best-selling player in the NFL by midday Monday. Editor's Picks Source: Steelers surprised by Villanueva move Alejandro Villanueva's appearance on the field, as the only Steelers player to leave the tunnel for Sunday's national anthem, led to "confusion" for some teammates, a source said. A spokesman for Fanatics, which runs the NFL's online store, confirmed to ESPN that, over the past 24 hours, more Villanueva gear, including jerseys and name and number T-shirts, has been ordered than that of any other NFL player. Villanueva beat out New England Patriots quarterback Tom Brady for the top spot. Philadelphia Eagles quarterback Carson Wentz, Dallas Cowboys quarterback Dak Prescott and Green Bay Packers quarterback Aaron Rodgers rounded out the top five over the past day. Both the NFL Shop and Fanatics websites had Villanueva jerseys and T-shirts in men's and women's sizes. A former Army Ranger who earned a Bronze Star and served three tours in Afghanistan, Villanueva was the only Steelers player who came outside the tunnel during Sunday's national anthem, after the team collectively decided not to be on the sideline during the song. Pictures and video of Villanueva standing, with his hand on his heart, filled social media networks. Alejandro Villanueva stood outside the tunnel for the national anthem while his Steelers teammates remained in the locker room. AP Photo/Nam Y. Huh His actions weren't supported by all, including his own coach. Asked after the Steelers' 23-17 loss to the Chicago Bears what he thought of Villanueva's positioning for the anthem, Mike Tomlin responded, "I was looking for 100 percent participation. We were gonna be respectful of our football team." While Villanueva, a Spanish-American, already has a strong following in Latin America, it is unprecedented to see an offensive lineman rise to the top of NFL player sales for any period of time. The only comparison of an out-of-nowhere player to see a rise to the top was backup defensive end Devon Still, whose Cincinnati Bengals jersey became one of the league's most popular jerseys in 2014, after his daughter's fight with cancer became public. "I don't know if the most effective way is to sit down during the national anthem with a country that's providing you freedom, providing you $16 million a year ... when there are black minorities that are dying in Iraq and Afghanistan for less than $20,000 a year," Villanueva told ESPN last year, when San Francisco 49ers quarterback Colin Kaepernick first started kneeling. Roughly 180 players didn't stand for the national anthem Sunday. Three teams -- the Steelers, Tennessee Titans and Seattle Seahawks -- didn't come to the sideline for the song.

– Reaction to the national anthem brouhaha between President Trump and the NFL continues to resonate Monday afternoon. Among those generating attention is Tom Brady, who voiced his disagreement with President Trump on the Kirk and Callahan radio show on Boston's WEEI. “Yeah, I certainly disagree with what (Trump) said. I thought it was just divisive," Brady said. "Like I said, I just want to support my teammates. I am never one to say, ‘Oh, that is wrong. That is right.’" Brady didn't kneel during the anthem Sunday, but he did lock arms with teammates. The QB has been on friendly terms with Trump, though he generally keeps his politics to himself. Related: Lone Steeler: Pittsburgh Steelers offensive lineman Alejandro Villanueva, a former Army Ranger who served three tours in Afghanistan, was the lone member of his team to emerge from the tunnel Sunday during the national anthem. On Monday, his jersey was the top-selling one of all NFL players, reports ESPN. (Meanwhile, Steelers fans angry at the team boycott were burning their gear, reports CBS Pittsburgh.) Earnardt Jr: NASCAR might be taking a stand against anthem protests, but driver Dale Earnhardt Jr. made clear where his sympathies lie in a tweet quoting John F. Kennedy. "All Americans R granted rights 2 peaceful protests," he wrote. "Those who make peaceful revolution impossible will make violent revolution inevitable-JFK" No games here: A restaurant owner in Greenville, South Carolina, announced that he'd no longer show NFL games until "all players show respect to our flag and our country," reports Fox Carolina. How this began: In the New York Times, Eric Reid of the San Francisco 49ers writes about joining teammate Colin Kaepernick in the early days of the anthem protests over police brutality. "We chose to kneel because it’s a respectful gesture. I remember thinking our posture was like a flag flown at half-mast to mark a tragedy." He adds that he's angry Trump "referred to us with slurs but the neo-Nazis in Charlottesville, Va., as 'very fine people.'" No love lost: The BBC notes that Trump has a long history of bad blood with the NFL, starting with his purchase of a team in the fledgling USFL in 1984. He also tried unsuccessfully to buy the Buffalo Bills in 2014. Political savvy: Rich Lowry makes the case at the National Review that this controversy illustrates why Trump is president. "He takes a commonly held sentiment—most people don’t like the NFL protests—and states it in an inflammatory way guaranteed to get everyone’s attention and generate outrage among his critics," writes Lowry. "When those critics lash back at him, Trump is put in the position of getting attacked for a fairly commonsensical view." And it's not calculated, just Trump operating on instinct. No punishment: The league says it will not penalize any players or teams who refused to take the field for the national anthem on Sunday, reports the Washington Post. Read a roundup of editorials and opinions here.

in the field of parallel and distributed systems , interconnection networks are an important research area . typically , the topology of a network can be represented as a graph in which the vertices represent processors and the edges represent communication links . for graph definitions and notations , we follow @xcite . a graph @xmath4 consists of a vertex set @xmath5 and an edge set @xmath6 , where an edge is an unordered pair of distinct vertices of @xmath4 . a graph @xmath4 is called bipartite if its vertex set can be partitioned into two parts @xmath7 such that every edge has one endpoint in @xmath8 and one in @xmath9 . a vertex @xmath10 is a neighbor of @xmath11 if @xmath12 is an edge of @xmath4 , and @xmath13 denotes all the neighbors of @xmath11 in @xmath4 . a path @xmath14 of length @xmath15 from @xmath16 to @xmath17 is a finite sequence of distinct vertices @xmath18 such that @xmath19 , and @xmath20 for @xmath21 . we also denote the path @xmath14 as @xmath22 , where @xmath23 is the path @xmath24 . a cycle @xmath25 of length @xmath26 is a closed path@xmath27 . a path ( resp . , cycle ) is called a hamiltonian path ( resp . , cycle ) if it contains all the vertices of @xmath4 . a graph @xmath4 is said to be hamiltonian if there is a hamiltonian cycle . a graph @xmath4 is said to be hamiltonian connected if there is a hamiltonian path between any two vertices of @xmath4 . a bipartite graph is hamiltonian laceable if there is a hamiltonian path between any two vertices in different bipartite sets . the hamiltonian property is one of the major requirements in designing network topologies since a topology structure containing hamiltonian paths or cycles can efficiently simulate many algorithms that are designed on linear arrays or rings @xcite . it is important to consider fault - tolerance in networks since faults may occur in real networks . two fault models have been studied in many well - known networks , one is the random fault model , which means that faults may occur anywhere without any restriction , see , for example , @xcite . the other is the conditional fault model , which assumes that the fault distribution is limited . for example , some studies on two or more non - faulty edges incident to each vertex can be found in @xcite . the hypercube network has been proved to be one of the most popular interconnection networks because it possesses many excellent properties such as a recursive structure , regularity , and symmetry . the balanced hypercube , proposed by huang and wu @xcite , is a hypercube variant . similar to hypercubes , balanced hypercubes are bipartite graphs @xcite that are vertex - transitive @xcite and edge - transitive @xcite . balanced hypercubes are superior to hypercubes in that they have a smaller diameter than hypercubes@xcite . the balanced hypercube , @xmath0 , has been studied by many researchers in recent years . @xcite proved that @xmath0 is edge - bipancyclic and hamiltonian laceable . yang @xcite proved that @xmath0 is bipanconnected . yang @xcite also demonstrated that the super connectivity of @xmath0 is @xmath28 and the super edge - connectivity of @xmath0 is @xmath29 for @xmath3 . @xcite proved that @xmath0 is hyper - hamiltonian laceable . cheng et al . @xcite proved that @xmath0 is @xmath30-vertex - fault - tolerant edge - bipancyclic . hao et al . @xcite showed that there is a fault - free hamiltonian path between any two adjacent vertices in @xmath0 with @xmath31 faulty edges . cheng et al . @xcite proved that @xmath0 is @xmath32 edge - fault - tolerant @xmath33-edge - bipancyclic for all @xmath34 . zhou et al . @xcite proved that @xmath0 is @xmath31 edge - fault - tolerant hamiltonian laceable , and they proposed an interesting problem that whether there is a fault - free hamiltonian cycle in @xmath0 with each vertex incident to at least two fault - free edges . in this paper , we consider this problem and show that each fault - free edge lies on a fault - free hamiltonian cycle in @xmath0 after no more than @xmath2 faulty edges occur if each vertex is incident with at least two fault - free edges for all @xmath3 . our result is optimal with respect to the maximum number of tolerated edge faults . the rest of this paper is organized as follows . in section @xmath35 , we introduce two equivalent definitions of balanced hypercubes and discuss some of their properties . in section @xmath36 , we introduce some lemmas used in the proof of the main result and prove the main result . finally , we conclude this paper and give an example to show that our result is optimal in section @xmath37 . wu and huang @xcite present two equivalent definitions of @xmath0 as follows : an @xmath38-dimensional balanced hypercube @xmath0 has @xmath39 vertices , each labeled by an @xmath38-bit string @xmath40 , where @xmath41 for all @xmath42 . an arbitrary vertex @xmath43 , @xmath44 is adjacent to the following @xmath45 vertices : @xmath46 in @xmath0 , the first coordinate @xmath47 of vertex @xmath40 is called the inner index , and the second coordinate @xmath48 is called the @xmath49-dimension index . from the definition , we have @xmath50 . figure [ bh2 ] shows two balanced hypercubes of dimensional one and two . and @xmath51,title="fig:",scaledwidth=60.0% ] + briefly , we assume that ` @xmath52 ' for the coordinate of a vertex is an operation with mod 4 in the remainder of the paper . let @xmath53 for @xmath54 and @xmath55 and let @xmath56 $ ] . then , @xmath0 can be divided into four copies : @xmath57 , and @xmath58 where @xmath59 for @xmath60 @xcite . we use @xmath61 to denote @xmath62 for @xmath63 . an @xmath38-dimensional balanced hypercube @xmath0 can be constructed recursively as follows : 1 . @xmath64 is a cycle of length four with vertex - set @xmath65 . 2 . @xmath66 is a construct from four copies of @xmath67 , and @xmath68 . each vertex @xmath69 , @xmath70 has two extra adjacent vertices : + @xmath71 since @xmath0 is a bipartite graph , @xmath72 can be divided into two disjoint parts . obviously , the vertex - set @xmath73 with @xmath74 odd@xmath75 and @xmath76 with @xmath74 even@xmath75 form the desired partition . we use black nodes to denote the vertices in @xmath8 and white nodes to denote the vertices in @xmath9 . let @xmath12 be an edge of @xmath0 . if @xmath11 and @xmath10 differ only with regard to the inner index , then @xmath12 is said to be a 0-dimension edge . if @xmath11 and @xmath10 differ not only in terms of the inner index but also with regard to the @xmath49-dimension index , then @xmath12 is called the @xmath49-dimension edge . we use @xmath77 to denote the set of all @xmath78-dimension edges . there are some known properties about @xmath0 . ( @xcite)[l1 ] the balanced hypercube @xmath0 is vertex - transitive and edge - transitive . a bipartite graph @xmath4 is @xmath79-fault - tolerant hamiltonian laceable if @xmath80 remains hamiltonian laceable for @xmath81 with @xmath82 . a bipartite graph @xmath4 is @xmath79-edge - fault - tolerant hamiltonian laceable if @xmath80 remains hamiltonian laceable for @xmath83 with @xmath82 . zhou et al . obtained the following result . ( @xcite)[l2 ] the balanced hypercube @xmath0 is @xmath84-edge - fault - tolerant hamiltonian laceable for @xmath3 . ( @xcite)[l3 ] let @xmath3 . then , @xmath85 has four components , and each component is isomorphic to @xmath86 . the above lemma shows that one can divide @xmath0 into four @xmath0s by deleting @xmath87 for any @xmath88 . the four components of @xmath89 are @xmath90 , @xmath91 , @xmath92 , and @xmath58 for @xmath54 . for convenience , we use @xmath93 , and @xmath94 to denote the components of @xmath85 throughout this paper . ( @xcite)[l4 ] let @xmath95 be two distinct bipartitions of @xmath0 , @xmath96 be two different vertices in @xmath97 , and @xmath98 be two different vertices in @xmath99 . then , there are two disjoint paths @xmath100 such that @xmath101 @xmath14 joins @xmath102 and @xmath103 , and @xmath23 joins @xmath104 and @xmath105 ; @xmath106 @xmath107 . a graph @xmath4 is hyper - hamiltonian laceable if it is hamiltonian laceable and , for an arbitrary vertex @xmath10 in @xmath108 where @xmath109 , there is a hamiltonian path in @xmath110 joining any two different vertices in @xmath111 . l et al . obtained the following result . ( @xcite)[l5 ] the balanced hypercube @xmath0 is hyper - hamiltonian laceable for @xmath112 . in this section , we will give the proof of the main result . first , we introduce some lemmas that will be used in the proof of the main result . suppose that @xmath4 is a graph and @xmath83 . a vertex @xmath11 is called @xmath49-rescuable in @xmath4 if @xmath113 . [ p2 ] let @xmath114 with @xmath115 and @xmath116 . then , at least one statement holds in the following @xmath101 and @xmath106 . @xmath101 there is an integer @xmath117 in @xmath118 such that @xmath119 and @xmath120 . @xmath106 there are two integers @xmath121 in @xmath118 such that @xmath122 and @xmath123 . furthermore , there is no isolated vertex and no more than one @xmath124-rescuable vertex in @xmath125 ( resp . , @xmath126 ) . * proof : * let @xmath127 be a faulty set in @xmath128 with @xmath115 and @xmath129 . suppose that @xmath11 is @xmath79-rescuable , and @xmath10 is @xmath130-rescuable in @xmath0 where @xmath131 is @xmath117-rescuable in @xmath0 , where @xmath132 . if @xmath133 , there is an integer @xmath134 such that @xmath135 because @xmath136 . each vertex is at least @xmath35-rescuable in @xmath125 for @xmath133 . thus , statement @xmath101 holds . in the following , we assume that @xmath137 and suppose that the dimensions of fault - free edges incident with @xmath11 are @xmath138 and the dimensions of fault - free edges incident with @xmath10 are @xmath139 where @xmath140 and @xmath141 may be multisets . * case 1 : * @xmath142 . * subcase 1.1 : * @xmath143 . in this subcase , @xmath144 . since @xmath145 , we obtain @xmath146 , and there is no faulty edge in @xmath147 . note that there is no triangle in @xmath0 . for an arbitrary vertex @xmath16 in @xmath148 , @xmath16 is incident with no more than one faulty edge , which means that @xmath16 is at least @xmath36-rescuable in @xmath149 for all @xmath150 as @xmath151 . note that for @xmath152 , there is an @xmath153 such that @xmath135 . if @xmath154 , then @xmath11 and @xmath10 are @xmath35-rescuable in @xmath125 . therefore , statement @xmath101 holds . if @xmath155 , without loss of generality , let @xmath156 . note that each vertex in @xmath0 is incident with two @xmath49-dimension edges for @xmath150 . the integer @xmath117 appears no more than once in the multiset @xmath157 . thus , @xmath11 is @xmath124-rescuable , and @xmath10 is @xmath35-rescuable in @xmath125 . note that for @xmath158 , according to the pigeonhole principle , there is an integer @xmath159 such that @xmath160 appears no more than once in the multiset @xmath161 . thus , @xmath162 . without loss of generality , we can assume that @xmath11 is @xmath124-rescuable and @xmath10 is @xmath35-rescuable in @xmath163 . therefore , statement @xmath106 holds . * subcase 1.2 : * @xmath164 . first , we prove that each vertex in @xmath148 is at least @xmath35-rescuable in @xmath149 for all @xmath165 . if @xmath166 , there are @xmath2 faulty edges incident with @xmath11 or @xmath10 . this means there is no faulty edge in @xmath147 . thus , each vertex in @xmath148 is incident with no more than two faulty edges . that means it is at least @xmath35-rescuable in @xmath149 for all @xmath165 since @xmath167 . if @xmath146 , there are @xmath168 faulty edges incident with @xmath11 or @xmath10 . this means that there is no more than one faulty edge in @xmath147 . since there is no triangle in @xmath0 , each vertex in @xmath148 is incident with no more than two faulty edges . that implies that it is at least @xmath35-rescuable in @xmath149 for all @xmath165 , as @xmath167 . next , we complete the proof of subcase @xmath169 . if there is an @xmath153 such that @xmath170 , then @xmath135 and @xmath11 and @xmath10 are at least @xmath35-rescuable in @xmath125 . therefore , statement @xmath101 holds . now , we assume that @xmath171 . if @xmath172 or @xmath173 and @xmath174 , there are two distinct integers @xmath121 in @xmath175 . note that @xmath11 is incident with two faulty @xmath117 ( resp . , @xmath160)-dimension edges and @xmath11 is @xmath35-rescuable , @xmath10 is at least @xmath124-rescuable in @xmath125 ( resp . , @xmath163 ) . therefore , statement @xmath106 holds . if @xmath173 and @xmath176 , without loss of generality , let @xmath177 . then @xmath178 . thus , @xmath11 is @xmath35-rescuable , and @xmath10 is at least @xmath124-rescuable in @xmath179 . let @xmath180 be the set of faulty edges incident with @xmath11 or @xmath10 . then @xmath181 and @xmath182 . moreover , @xmath183 . further , we obtain @xmath184 or @xmath185 , as @xmath186 . without loss of generality , we can assume that @xmath184 . since @xmath11 is incident with exactly one faulty @xmath187-dimension edge , @xmath10 is incident with at least one faulty @xmath187-dimension edge . thus , @xmath187 appears no more than once in the multiset @xmath188 . note that @xmath11 is @xmath124-rescuable , @xmath10 is at least @xmath35-rescuable in @xmath85 and @xmath189 . let @xmath190 . therefore , statement @xmath106 holds . * subcase 1.3 : * @xmath191 . since @xmath191 , each vertex in @xmath192 is at least @xmath35-rescuable in @xmath149 for all @xmath165 . suppose that there are two distinct integers @xmath193 . note that @xmath11 is incident with two faulty @xmath117 ( resp . , @xmath160)-dimension faulty edges , and @xmath11 is @xmath35-rescuable in @xmath125 ( resp . , @xmath163 ) . then , statement @xmath106 holds . if there are nt two distinct integers @xmath193 , then @xmath194 and @xmath195 . without loss of generality , we can assume that @xmath177 . then , @xmath196 . if @xmath197 , then @xmath11 is @xmath35-rescuable in @xmath179 . therefore , statement @xmath101 holds . if @xmath198 , then @xmath11 is @xmath35-rescuable in @xmath179 . according to the pigeonhole principle , @xmath199 or @xmath200 . without loss of generality , we can assume that @xmath199 . thus , @xmath11 is @xmath124-rescuable in @xmath85 . let @xmath190 . therefore , statement @xmath106 holds . * case 2 : * @xmath201 . * subcase 2.1 : * @xmath164 . \(a ) there is a @xmath36-rescuable vertex @xmath202 in @xmath0 where @xmath203 . suppose that the dimensions of fault - free edges incident with @xmath202 are @xmath204 . note that @xmath205 and there is no triangle in @xmath0 . we obtain @xmath173 and @xmath206)|=|f\cap e(bh_n[\{u , v , w\}])|=2 $ ] . without loss of generality , let @xmath207 . since @xmath208 , @xmath209 . hence , each vertex in @xmath210 is incident with no more than two faulty edges . this means that each vertex in @xmath210 is at least @xmath35-rescuable in @xmath149 for all @xmath211 . note that @xmath212 . there is an integer @xmath134 such that @xmath213 . without loss of generality , we can assume that @xmath214 . since each vertex is incident with exactly two @xmath187-dimension edges , @xmath187 appears no more than three times in the multiset @xmath215 . if @xmath187 does not appear twice in the multiset @xmath216 , @xmath188 and @xmath217 , then @xmath218 are at least @xmath35-rescuable in @xmath85 . thus , statement @xmath101 holds . otherwise , without loss of generality , assume that @xmath219 . then , @xmath11 is @xmath124-rescuable , and @xmath10 and @xmath202 are at least @xmath35-rescuable in @xmath85 . moreover , @xmath11 is @xmath35-rescuable in both @xmath220 and @xmath179 . if @xmath35 appears four times in the multiset @xmath221 , then @xmath222 . note that @xmath223 are at least @xmath35-rescuable in @xmath220 . then , let @xmath224 . statement @xmath106 holds . if @xmath35 appears no more than three times in the multiset @xmath221 , then one of the vertices in @xmath225 is at least @xmath35-rescuable , and another is at least @xmath124-rescuable in @xmath179 . let @xmath190 . statement @xmath106 holds . \(b ) suppose that each vertex in @xmath148 is at least @xmath37-rescuable in @xmath0 . note that each vertex in @xmath148 is at least @xmath35-rescuable in @xmath149 for all @xmath150 . let @xmath180 be the set of faulty edges incident with @xmath11 or @xmath10 . then , @xmath226 . if there is an integer @xmath153 such that @xmath227 , then @xmath117 appears no more than once in the multiset @xmath228 . thus , @xmath11 ( resp . , @xmath10 ) is at least @xmath35-rescuable in @xmath125 . statement @xmath101 holds . otherwise , @xmath173 and @xmath229 for all @xmath230 . then , there are two distinct integers @xmath231 such that @xmath106 holds . in fact , there are two integers @xmath232 such that @xmath233 and @xmath234 , as @xmath235 . thus , @xmath117 ( resp . , @xmath160 ) appears no more than twice in the multiset @xmath228 . hence , one vertex in @xmath236 is at least @xmath35-rescuable and another is at least @xmath124-rescuable in @xmath125 ( resp . , @xmath163 ) . statement @xmath106 holds . * subcase 2.2 : * @xmath237 . note that for @xmath191 , each vertex in @xmath192 is at least @xmath35-rescuable in @xmath149 for all @xmath238 . since @xmath239 , there is an integer @xmath117 such that @xmath135 . if @xmath117 appears no more than once in the multiset @xmath216 , then @xmath11 is at least @xmath35-rescuable in @xmath125 . statement @xmath101 holds . if @xmath117 appears twice in the multiset @xmath216 , without loss of generality , let @xmath240 . then , @xmath11 is @xmath124-rescuable in @xmath125 and let @xmath160 be an integer in @xmath241 . then @xmath11 is incident with two faulty @xmath160-dimension edges and @xmath11 is @xmath36-rescuable in @xmath163 . hence , statement @xmath106 holds . owing to the above discussion , the lemma holds . @xmath242 [ p5 ] let @xmath114 with @xmath243 . then , for any vertex @xmath11 in @xmath244 , there is a fault - free @xmath245-dimension edge @xmath246 such that @xmath247 . moreover , if @xmath11 is @xmath124-rescuable in @xmath89 , then @xmath12 can be a faulty edge . * proof : * each vertex in @xmath72 is incident with two @xmath49-dimension edges for all @xmath150 . thus , for any vertex @xmath248 , its degree is @xmath31 in @xmath244 . there is at least one fault - free @xmath245-dimension edge @xmath246 such that @xmath247 for @xmath249 . if @xmath11 is incident with only one fault - free edge in @xmath244 , then @xmath11 is incident with @xmath32 faulty edges in @xmath244 . thus , @xmath250 . since @xmath251 , there is at least one fault - free edge @xmath252 such that @xmath146 . @xmath242 [ l6 ] let @xmath253 with @xmath254 and @xmath255 . then , each edge in @xmath256 lies on a fault - free hamiltonian cycle . * proof : * the proof is rather long , so we provide it in appendix a. @xmath242 [ t1 ] let @xmath257 with @xmath243 and @xmath258 . then , each edge in @xmath259 lies on a fault - free hamiltonian cycle . * proof : * we prove this theorem by induction on @xmath38 . by lemma [ l6 ] , the theorem holds for @xmath260 . assume that this is true for @xmath261 . by lemma [ p2 ] , one may partite @xmath0 along dimension @xmath245 , @xmath262 , into four @xmath263 , denoted by @xmath57 and @xmath58 , such that @xmath264 and there is no isolated vertex and no more than one @xmath124-rescuable vertex in @xmath89 . let @xmath265 and @xmath266 be an arbitrary edge in @xmath259 . we must show that there is a hamiltonian cycle in @xmath259 that contains @xmath267 . * case 1 : * @xmath268 . without loss of generality , we can assume that @xmath269 . * subcase 1.1 : * @xmath270 for all @xmath271 * subcase 1.1.1 : * @xmath272 . by lemma [ p2 ] , there is exactly one @xmath124-rescuable vertex in @xmath89 , say , @xmath202 . without loss of generality , we can assume that @xmath202 is a white vertex . * subcase 1.1.1.1 : * @xmath273 . since @xmath258 , @xmath202 is incident with at least one fault - free @xmath245 dimension edge , say , @xmath274 . by lemma [ p5 ] , there is a fault - free @xmath245-dimension edge @xmath275 such that @xmath276 . by induction , there is a hamiltonian cycle @xmath277 in @xmath278 that contains @xmath12 . since @xmath202 is incident with exactly two edges in @xmath278 , @xmath279 . we represent @xmath277 as @xmath280 . note that @xmath202 is incident with @xmath32 faulty edges in @xmath90 , so we have @xmath281 . hence @xmath282 . let @xmath283 be fault - free @xmath245-dimension edges . by lemma [ l2 ] , there is a fault - free hamiltonian path @xmath284 in @xmath244 that joins @xmath285 and @xmath286 for @xmath287 . then , the cycle @xmath288 ( see figure [ 1 - 1 - 1 - 1 ] ) is the desired cycle . , title="fig:",scaledwidth=40.0% ] + * subcase 1.1.1.2 : * @xmath289 ( or @xmath58 ) . since @xmath290 , @xmath291 for all @xmath292 . let @xmath293 , where @xmath294 and @xmath295}. since @xmath296=2n-4\ge 2 $ ] , we can obtain @xmath297 . moreover , if @xmath298 , there are @xmath31 faulty edges between @xmath90 and @xmath91 . * subcase 1.1.1.2.1 : * @xmath299 . by induction , there is a fault - free hamiltonian cycle @xmath277 in @xmath90 that contains @xmath12 and a hamiltonian cycle @xmath300 in @xmath301 that contains @xmath274 . suppose that @xmath302 . let @xmath303 . note that @xmath298 , so there are @xmath31 faulty @xmath245-dimension edges between @xmath90 and @xmath91 . thus , @xmath304 . let @xmath305 be fault - free @xmath245-dimension edges . note that @xmath291 for @xmath306 . by lemma [ l2 ] , there is a hamiltonian path @xmath284 of @xmath244 that joins @xmath285 and @xmath286 for @xmath306 . hence , the cycle @xmath307 ( see figure [ 1 - 1 - 1 - 2 ] ) is the desired cycle . * subcase 1.1.1.2.2 : * @xmath308 . \(a ) @xmath309 . let @xmath310 and @xmath311 be a fault - free @xmath245-dimension edge . by induction , there is a fault - free hamiltonian cycle @xmath277 in @xmath90 that contains @xmath12 . suppose that @xmath312 . note @xmath309 ; we can see that @xmath313 or @xmath314 is incident with one fault - free @xmath245-dimension edge . without loss of generality , we can assume that @xmath313 is incident with one fault - free @xmath245-dimension edge , say , @xmath275 . we can represent @xmath277 as @xmath315 . let @xmath316 be a fault - free @xmath245-dimension edge . note that @xmath317 for @xmath306 . by lemma [ l2 ] , there is a fault - free hamiltonian path @xmath284 in @xmath244 that joins @xmath285 and @xmath286 for @xmath306 . by induction , there is a fault - free hamiltonian cycle @xmath300 in @xmath91 that contains @xmath274 as @xmath318 and @xmath319 . let @xmath320 . then , the cycle @xmath321 ( see figure [ 1 - 1 - 1 - 2 ] ) is the desired cycle . , title="fig:",scaledwidth=80.0% ] + \(b ) @xmath322 . since @xmath323 + 4+(2n-3)=4n-3 > 4n-5 $ ] , each vertex is at least @xmath36-rescuable in @xmath90 . let @xmath324 be a fault - free edge in @xmath90 where @xmath325 . let @xmath326 where @xmath327 . then , @xmath328=4n-10 $ ] , and @xmath329 . let @xmath310 . by lemma [ p5 ] , there is a fault - free @xmath245-dimension edge @xmath275 such that @xmath330 . by induction , there is a hamiltonian cycle @xmath277 in @xmath331 that contains @xmath332 . since @xmath11 is incident with exactly two fault - free edges in @xmath333 , @xmath334 . we represent @xmath277 as @xmath315 . also by induction , there is a hamiltonian cycle in @xmath301 that contains @xmath274 . let @xmath320 and @xmath316 be a fault - free @xmath245-dimension edge . note that @xmath291 for @xmath306 . by lemma [ l2 ] , there is a hamiltonian path @xmath284 in @xmath244 that joins @xmath285 and @xmath286 for @xmath306 . then , the cycle @xmath321 ( see figure [ 1 - 1 - 1 - 2 ] ) is the desired cycle . * subcase 1.1.1.3 : * @xmath335 . since @xmath129 , @xmath202 is incident with a fault - free @xmath245-dimension edge @xmath336 . by lemma [ p5 ] , there is a fault - free @xmath245-dimension edge @xmath337 such that @xmath338 . by induction , there is a fault - free hamiltonian cycle @xmath277 in @xmath90 that contains @xmath12 . we represent it as @xmath339 with @xmath340 . let @xmath341 . therefore , @xmath342 is a set of @xmath343 mutually disjoint edges . there is an edge @xmath344 in @xmath342 such that @xmath345 ( resp . , @xmath346 ) is incident with a fault - free @xmath245-dimension edge , say , @xmath347 ( resp . , @xmath348 ) because @xmath349 . we can represent @xmath277 as @xmath350 . , title="fig:",scaledwidth=40.0% ] + note that @xmath291 for @xmath351 . by lemma [ l2 ] , there is a fault - free hamiltonian path @xmath284 in @xmath244 that joins @xmath285 and @xmath286 for @xmath351 . by induction , there is a hamiltonian cycle @xmath352 in @xmath353 that contains @xmath311 . let @xmath354 . then , the cycle @xmath355 ( see figure [ 1 - 1 - 1 - 3 ] ) is the desired cycle . * case 1.1.2 : * @xmath356 . since @xmath357 , there is an integer @xmath358 such that @xmath291 . without loss of generality , we can assume that @xmath359 . by induction , there is a fault - free hamiltonian cycle @xmath277 in @xmath90 that contains @xmath12 . similar to the analysis of subcase 1.1.1.3 , we can represent @xmath277 as @xmath350 where @xmath360 are fault - free @xmath245-dimension edges . by lemma [ p5 ] , there is a fault - free @xmath245-dimension edge @xmath361 such that @xmath362 . in addition , by lemma [ p5 ] , there is a fault - free @xmath245-dimension edge @xmath363 such that @xmath364 . by induction , there is a hamiltonian cycle @xmath365 in @xmath366 that contains @xmath367 for @xmath306 . let @xmath368 for i=2 , 3 . by lemma [ l2 ] , there is a fault - free hamiltonian path @xmath369 in @xmath91 that joins @xmath370 and @xmath371 . hence , the cycle @xmath372 ( see figure [ 1 - 1 - 2 ] ) is the desired cycle . , title="fig:",scaledwidth=40.0% ] + * subcase 1.2 : * there is an integer @xmath373 such that @xmath374 . if @xmath375 , there are at least two vertex - disjoint faulty edges for @xmath376=2n-4\ge 1 $ ] . note that @xmath309 . then , there is a faulty edge @xmath377 such that @xmath378 is incident with a fault - free @xmath245-dimension edge and @xmath379 is incident with a fault - free @xmath245-dimension edge . suppose that @xmath380 . note that there is no more than one @xmath124-rescuable vertex in @xmath381 . let @xmath378 be the @xmath124-rescuable vertex in @xmath244 . since @xmath129 , @xmath378 is incident with a fault - free @xmath245-dimension edge . by lemma [ p5 ] , there is a fault - free @xmath245-dimension edge @xmath382 such that @xmath383 . obviously , @xmath384 . owing to the above discussion , there is an edge @xmath383 such that @xmath101 @xmath378 is incident with a fault - free @xmath245-dimension edge ; @xmath106 @xmath379 is incident with a fault - free @xmath245-dimension edge ; @xmath385 @xmath384 , where @xmath374 for @xmath373 . * subcase 1.2.1 : * @xmath386 . by induction , there is a hamiltonian cycle @xmath277 that contains @xmath12 in @xmath387 . obviously , @xmath388 . if @xmath389 , let @xmath390 . if @xmath391 , let @xmath332 be an edge such that @xmath392 ( resp . , @xmath313 ) is incident with a fault - free @xmath245-dimension edge . we can represent the cycle @xmath277 as @xmath315 for @xmath393 , @xmath332 exists . let @xmath394 be fault - free @xmath245-dimension edges . by lemma [ l2 ] , there is a fault - free hamiltonian path @xmath284 that joins @xmath367 in @xmath244 for @xmath287 . the cycle @xmath395 ( see figure [ 1 - 2 - 1 ] ) is the desired cycle . , title="fig:",scaledwidth=38.0% ] + * subcase 1.2.2 : * @xmath396 ( or @xmath397 ) . in this subcase , @xmath398 . by induction , there is a hamiltonian cycle @xmath300 in @xmath399 that contains @xmath400 , where @xmath102 ( resp . , @xmath103 ) is incident with a fault - free @xmath245-dimension edge . we can assume that @xmath401 and @xmath402 , @xmath337 are fault - free @xmath245-dimension edges incident with @xmath370 or @xmath371 . let @xmath403 . since @xmath398 and @xmath404 , we can choose two fault - free edges @xmath405 such that @xmath313 is incident with a fault - free @xmath245-dimension edge @xmath275 . particularly , if @xmath406 , let @xmath407 . let @xmath326 where @xmath408 . then , @xmath409 and @xmath410 . by induction , there is a hamiltonian cycle @xmath277 in @xmath90 that contains @xmath12 . since @xmath392 is incident with exactly two fault - free edges in @xmath333 , we have @xmath411 . we represent @xmath277 as @xmath315 . let @xmath316 be the fault - free @xmath245-dimension edge . by lemma [ l2 ] , there is a fault - free hamiltonian path @xmath284 in @xmath244 that joins @xmath285 and @xmath286 for @xmath306 . hence , the cycle @xmath395 ( see figure [ 1 - 2 - 2 ] ) is the desired cycle . , title="fig:",scaledwidth=40.0% ] + * subcase 1.2.3 : * @xmath412 . by induction , there is a hamiltonian in @xmath413 that contains @xmath414 and @xmath104 ( resp . , @xmath105 ) is incident with a fault - free @xmath245-dimension edge . we can assume that @xmath415 and @xmath316 , @xmath337 are fault - free @xmath245-dimension edges . let @xmath416 . by induction , there is a fault - free hamiltonian cycle @xmath277 in @xmath90 that contains @xmath12 . similar to the analysis of subcase 1.1.1.3 , we can represent @xmath277 as @xmath350 where @xmath345 ( resp . , @xmath346 ) is incident with a fault - free @xmath245-dimension edge @xmath347 ( resp . , @xmath417 ) . by lemma [ l2 ] , there is a fault - free hamiltonian path @xmath284 of @xmath244 that contains @xmath367 for @xmath351 . hence , the cycle @xmath418 , @xmath419 ( see figure [ 1 - 2 - 3 ] ) is the desired cycle . , title="fig:",scaledwidth=38.0% ] + * subcase 1.3 : * there is an integer @xmath49 in @xmath65 such that @xmath420 . we prove this subcase according to two cases below . * subcase 1.3.1 * @xmath421 for all @xmath422 . since @xmath423 , there are at least three disjoint faulty edges . there are two faulty edges @xmath424 such that @xmath425 are incident with four disjoint fault - free @xmath245-dimension edges owing to @xmath426 . * subcase 1.3.1.1 : * @xmath427 . by induction , there is a hamiltonian cycle @xmath277 in @xmath428 that contains @xmath12 . if @xmath429 , according to subcase @xmath430 , there is a desired cycle . if @xmath431 , represent @xmath277 as @xmath432 ( or @xmath433 , @xmath434 ) . let @xmath435 be fault - free @xmath245-dimension edges such that @xmath436 for all @xmath60 . by lemma [ l4 ] , there are two disjoint paths @xmath437 such that @xmath438 @xmath284 joins @xmath285 and @xmath286 , @xmath439 joins @xmath440 and @xmath441 ; @xmath106 @xmath442 for @xmath287 . hence , the cycle @xmath443 , @xmath444 , @xmath445 , @xmath446(or the cycle @xmath447 , @xmath448 , @xmath449 , @xmath450 ) ( see figure [ 1 - 3 - 1 - 1 ] ) is the desired cycle . , title="fig:",scaledwidth=95.0% ] + * subcase 1.3.1.2 : * @xmath451 ( or @xmath452 ) . by induction , there is a hamiltonian cycle @xmath300 in @xmath453 that contains @xmath454 . if @xmath455 , according to subcase @xmath456 , there is a desired cycle . thus , assume that @xmath457 . we can assume that @xmath458 ( or @xmath459 ) and that @xmath460 are fault - free @xmath245-dimension edges . note that @xmath461 . then , @xmath462 or @xmath463 . without loss of generality , we assume that @xmath463 . if there is a vertex @xmath464 in @xmath90 incident with two faulty @xmath245-dimension edges , let @xmath465 . otherwise , let @xmath466 @xmath467 . since @xmath468 , @xmath469 . by induction , there is a hamiltonian cycle @xmath277 in @xmath333 that contains @xmath12 . we may represent it as @xmath432 . let @xmath470 be fault - free @xmath245-dimension edges where @xmath471 ( when @xmath459 , let @xmath472 be fault - free @xmath245-dimension edges ) . by lemma [ l4 ] , there are two disjoint paths @xmath437 such that @xmath438 @xmath284 joins @xmath285 and @xmath286 , and @xmath439 joins @xmath440 and @xmath441 ; @xmath106 @xmath442 for @xmath306 . hence , the cycle @xmath473 , @xmath474 @xmath475 ( or @xmath476 , @xmath477 , @xmath475 ) ( see figure [ 1 - 3 - 1 - 2 ] ) is the desired cycle . , title="fig:",scaledwidth=90.0% ] + * subcase 1.3.1.3 : * @xmath478 . , title="fig:",scaledwidth=89.0% ] + by induction , there is a hamiltonian cycle @xmath352 in @xmath479 that contains @xmath480 . if @xmath481 , according to subcase @xmath482 , there is a desired cycle . now , let @xmath483 . we can assume that @xmath484 ( or @xmath485 ) . let @xmath486 be fault - free @xmath245-dimension edges , where @xmath487 . by induction , there is a hamiltonian cycle @xmath277 that contains @xmath12 . since @xmath468 , there are two edges @xmath488 such that @xmath489 are fault - free @xmath245-dimension edges , where @xmath490 . we can represent @xmath277 as @xmath432 . by lemma [ l4 ] , there are two disjoint paths @xmath437 such that @xmath438 @xmath284 joins @xmath285 and @xmath286 , and @xmath439 joins @xmath440 and @xmath441 ; @xmath106 @xmath442 for @xmath491 . thus , the cycle @xmath492 @xmath493(or @xmath494 @xmath495 ) ( see figure [ 1 - 3 - 1 - 3 ] ) is the desired cycle . * subcase 1.3.2 : * @xmath496 for some @xmath373 . by lemma [ p2 ] , there is no more than one @xmath124-rescuable vertex in @xmath244 , say , @xmath202 . suppose that @xmath497 is the fault - free edge incident with @xmath202 . without loss of generality , we can assume that @xmath202 is a white vertex . since @xmath498 , @xmath202 is incident with at least three faulty edges in @xmath244 . then , there are two faulty edges @xmath499 such that @xmath500 are incident with two disjoint fault - free @xmath245-dimension edges owing to @xmath501 . * subcase 1.3.2.1 : * @xmath427 . by induction , there is a hamiltonian cycle @xmath277 in @xmath502 that contains @xmath12 . if @xmath503 , according to subcase @xmath430 , there is a desired cycle . now , we can assume that @xmath504 . \(a ) suppose that @xmath202 is incident with two fault - free @xmath245-dimension edges . , title="fig:",scaledwidth=40.0% ] + in this instance , we can represent @xmath277 as @xmath505 . let @xmath506 , @xmath507 , @xmath508 be fault - free @xmath245-dimension edges . by lemma [ l4 ] , there are two paths @xmath284 and @xmath439 such that @xmath509 joins @xmath285 and @xmath286 , and @xmath439 joins @xmath440 and @xmath441 ; @xmath510 for @xmath287 . thus , the cycle @xmath511 , @xmath512 ( see figure [ 1 - 3 - 2 - 1a ] ) is the desired cycle . \(b ) suppose that @xmath202 is incident with exactly one fault - free @xmath245-dimension edge @xmath274 . in this instance , we can represent @xmath277 as @xmath513 . suppose that @xmath514 is incident with a fault - free @xmath245-dimension edge @xmath515 where @xmath516 . let @xmath275 , @xmath517 and @xmath435 be fault - free @xmath245-dimension edges for @xmath518 . by lemma [ l4 ] , there are two paths @xmath284 and @xmath439 such that @xmath509 joins @xmath285 and @xmath286 , and @xmath439 joins @xmath440 and @xmath441 ; @xmath510 for @xmath287 . thus , the cycle @xmath519 , @xmath520 , @xmath521 ( see figure [ 1 - 3 - 2 - 1b ] ) is the desired cycle . suppose that the unique fault - free @xmath245-dimension edge incident with @xmath514 is @xmath522 . let @xmath275 , @xmath517 and @xmath435 be fault - free @xmath245-dimension edges for @xmath518 . by lemma [ l4 ] , there are two paths @xmath284 and @xmath439 in @xmath244 such that @xmath509 joins @xmath285 and @xmath286 , and @xmath439 joins @xmath440 and @xmath441 ; @xmath510 for @xmath306 . by lemma [ l5 ] , there is a hamiltonian path in @xmath523 that joins @xmath370 and @xmath524 . then , the cycle @xmath525 @xmath526 , @xmath434 ( see figure [ 1 - 3 - 2 - 1b ] ) is the desired cycle . , title="fig:",scaledwidth=90.0% ] + * subcase 1.3.2.2 : * @xmath420 for @xmath287 . by induction , there is a hamiltonian cycle @xmath365 in @xmath527 that contains @xmath497 . then , @xmath528 . according to subcase @xmath456 or @xmath482 , there is a desired cycle . * case 2 : * @xmath529 . if @xmath501 or @xmath272 , by lemma [ p2 ] , there is an integer @xmath530 such that @xmath531 and there is no isolated vertex and no more than one @xmath124-rescuable vertex in @xmath532 . note that @xmath533 . according to case @xmath124 , there is a desired cycle . thus , we only need to show that there is a hamiltonian cycle in @xmath259 that contains @xmath267 when @xmath356 and @xmath534 . without loss of generality , we can assume that @xmath535 . * subcase 2.1 : * @xmath270 for all @xmath60 . since @xmath536 , we have @xmath537 or @xmath538 . without loss of generality , we can assume that @xmath537 . by lemma [ p5 ] , there is a fault - free @xmath245-dimension edge @xmath337 ( resp . , ( @xmath539 ) ) such that @xmath540 ( resp . , @xmath541 ) . by lemma [ l2 ] , there is a hamiltonian path @xmath542 that joins @xmath11 and @xmath313 . by induction , there is a hamiltonian cycle @xmath365 in @xmath543 that contains @xmath367 for @xmath287 . let @xmath368 . the cycle @xmath544 ( see figure [ 2 - 1 ] ) is the desired cycle . , title="fig:",scaledwidth=35.0% ] + * subcase 2.2 : * there is an @xmath373 such that @xmath545 . * subcase 2.2.1 : * @xmath386 ( or @xmath396 ) . * subcase 2.2.1.1 : * suppose that @xmath11 is incident with at least two faulty edges in @xmath90 . since @xmath546 and each vertex is incident with exactly two @xmath245-dimension edges , there is a faulty edge @xmath547 such that @xmath313 is incident with a fault - free @xmath245-dimension edge , say , @xmath548 . by induction , there is a hamiltonian cycle @xmath277 in @xmath90 that contains @xmath547 . let @xmath549 and @xmath283 be fault - free @xmath245-dimension edges . by lemma [ l4 ] , there is a path @xmath284 in @xmath244 that joins @xmath285 and @xmath286 . therefore , the cycle @xmath550 ( see figure [ 2 - 2 - 1 - 1 ] ) is the desired cycle . , title="fig:",scaledwidth=35.0% ] + * subcase 2.2.1.2 : * suppose that @xmath11 is incident with no more than one faulty edge in @xmath90 . in this subcase , there are two disjoint faulty edges in @xmath551 , say , @xmath552 , that are the result of @xmath553 . suppose that @xmath554 is a white vertex and @xmath555 or @xmath556}. * subcase 2.2.1.2.1 : * @xmath557 . without loss of generality , we can assume that @xmath558 is a fault - free @xmath245-dimension edge where @xmath559 . \(a ) suppose that @xmath314 is incident with a fault - free @xmath245-dimension edge @xmath517 . note that @xmath11 is incident with no more than one faulty edge in @xmath90 . there is a vertex @xmath560 such that @xmath313 is incident with a fault - free @xmath245-dimension edge @xmath275 where @xmath561 owing to @xmath562 . by induction , there is a hamiltonian cycle @xmath277 in @xmath563 that contains @xmath547 . if @xmath564 , similar to subcase 2.2.1.1 , there is a desired cycle . thus , we can assume that @xmath565 . we can represent @xmath277 as @xmath566 . let @xmath435 be fault - free @xmath245-dimension edges for @xmath518 where @xmath436 . by lemma [ l4 ] , there are two vertex - disjoint paths @xmath284 and @xmath439 such that @xmath509 joins @xmath285 and @xmath286 , and @xmath439 joins @xmath440 and @xmath441 ; @xmath510 for @xmath287 . hence , the cycle @xmath567 @xmath568 , @xmath569 ( see figure [ 2 - 2 - 1 - 2 - 1 ] ( a ) ) is the desired cycle . \(b ) suppose that @xmath314 is incident with two faulty @xmath245-dimension edges . by induction , there is a hamiltonian cycle in @xmath570 that contains @xmath571 . since @xmath356 , @xmath314 is incident with a fault - free edge @xmath572 in @xmath90 , which does not belong to @xmath573 . without loss of generality , we can represent @xmath277 as @xmath574 . note that @xmath314 is incident with two faulty @xmath245-dimension edges , and @xmath575 are incident with two disjoint fault - free @xmath245-dimension edges @xmath576 . let @xmath435 be fault - free @xmath245-dimension edges where @xmath436 for @xmath518 . by lemma [ l4 ] , there are two hamiltonian paths @xmath437 such that @xmath509 joins @xmath285 and @xmath286 , and @xmath439 joins @xmath440 and @xmath441 ; @xmath510 for @xmath287 . thus , the cycle @xmath577 , @xmath578 ( see figure [ 2 - 2 - 1 - 2 - 1 ] ( b ) ) is the desired cycle . , title="fig:",scaledwidth=80.0% ] + * subcase 2.2.1.2.2 : * @xmath579 . in this subcase , @xmath580 and @xmath581 . by induction , there is a hamiltonian cycle @xmath277 in @xmath570 that contains @xmath571 . we can represent @xmath277 as @xmath566 . since @xmath313 is incident with two fault - free @xmath245-dimension edges , we can choose a fault - free @xmath245-dimension edge @xmath275 where @xmath561 . let @xmath435 be fault - free @xmath245-dimension edges for @xmath518 where @xmath582 . by lemma [ l4 ] , there are two vertex - disjoint paths @xmath284 and @xmath439 such that @xmath509 joins @xmath285 and @xmath286 , and @xmath439 joins @xmath440 and @xmath441 ; @xmath510 for @xmath583 . by lemma [ l5 ] , there is a hamiltonian path @xmath369 in @xmath584 that joins @xmath370 and @xmath524 . hence , the cycle @xmath585 ( see figure [ 2 - 2 - 1 - 2 - 2 ] ) is the desired cycle . , title="fig:",scaledwidth=38.0% ] + * subcase 2.2.2 : * @xmath412 ( or @xmath397 ) . there are two disjoint faulty edges in @xmath92 for @xmath586 . since @xmath587 , there is a faulty edge @xmath588 such that @xmath589 ( resp . , @xmath590 ) is incident with a fault - free @xmath245-dimension edge @xmath316 ( resp . , @xmath337 ) . by induction there is a hamiltonian cycle @xmath352 in @xmath591 that contains @xmath480 . let @xmath592 and @xmath548 be a fault - free @xmath245-dimension edge . by lemma [ l2 ] , there is a hamiltonian path @xmath284 in @xmath244 that joins @xmath285 and @xmath286 for @xmath593 . thus , the cycle @xmath544 ( see figure [ 2 - 2 - 2 ] ) is the desired cycle . , title="fig:",scaledwidth=35.0% ] + * lemma [ l6 ] * let @xmath253 with @xmath254 and @xmath255 . then , each edge in @xmath256 lies on a fault - free hamiltonian cycle . suppose that @xmath594 . by lemma [ l1 ] , without loss of generality , we can assume that @xmath595 . let @xmath266 . in the following , we can assume that @xmath596 are white vertices and @xmath500 are black vertices in @xmath597 for @xmath60 . * case 1 : * @xmath598 , @xmath599 . * subcase 1.1 : * @xmath600 . without loss of generality , we can assume that @xmath601 . since @xmath598 , there is an edge @xmath602 in @xmath603 such that @xmath16 ( resp . , @xmath17 ) is incident with a fault - free @xmath124-dimension edge . without loss of generality , we can assume that @xmath604 . let @xmath605 and @xmath606 be fault - free @xmath124-dimension edges . note that @xmath599 . there is a hamiltonian path @xmath284 in @xmath607 that joins @xmath285 and @xmath286 for @xmath287 . thus , the cycle @xmath608 ( see figure [ appendix])(a ) is the desired cycle . * subcase 1.2 : * @xmath609 . without loss of generality , we can assume that @xmath12 is an edge between @xmath610 and @xmath611 and @xmath612 . let @xmath613 be fault - free @xmath124-dimension edges . since @xmath599 , there is a hamiltonian path @xmath284 of @xmath597 that joins @xmath285 and @xmath286 for @xmath60 . thus , the cycle @xmath550 ( see figure [ appendix ] ( b ) ) is the desired cycle . * case 2 : * @xmath614 , @xmath615 . * subcase 2.1 : * @xmath600 . without loss of generality , we can assume that @xmath601 . * subcase 2.1.1 : * @xmath616 . suppose that @xmath332 is a faulty edge in @xmath610 . let @xmath617 . then , @xmath542 is a fault - free hamiltonian path in @xmath610 that contains @xmath12 . since @xmath255 , @xmath392 ( resp . , @xmath313 ) is incident with a fault - free @xmath124-dimension edge @xmath618 ( resp . , @xmath275 ) . let @xmath283 be fault - free @xmath124-dimension edges . since @xmath619 , there is a hamiltonian path @xmath284 in @xmath607 that joins @xmath285 and @xmath286 for @xmath287 . thus , the cycle @xmath620 ( see figure [ appendix ] ( c))is the desired cycle . * subcase 2.1.2 : * @xmath621(or @xmath622 ) . let @xmath623 and @xmath454 be the faulty edge in @xmath611 . suppose that @xmath624 . then , @xmath369 is a hamiltonian path in @xmath611 that joins @xmath370 and @xmath371 . since @xmath625 , @xmath370 ( resp . , @xmath371 ) is incident with a fault - free @xmath124-dimension edge . \(a ) @xmath626 . since @xmath614 and @xmath626 , @xmath313 is incident with at least one fault - free @xmath124-dimension edge , say , @xmath275 . let @xmath627 and @xmath283 be fault - free @xmath124-dimension edges . since @xmath628 , there is a hamiltonian path @xmath284 in @xmath607 that joins @xmath285 and @xmath286 for @xmath306 . hence the cycle @xmath629 ( see figure [ appendix ] ( d ) ) is the desired cycle . \(b ) @xmath630 . since @xmath631 , @xmath10 or @xmath313 is incident with a fault - free @xmath124-dimension edge . without loss of generality , we can assume that @xmath313 is incident with a fault - free @xmath124-dimension edge @xmath275 . let @xmath632 and @xmath283 be fault - free @xmath124-dimension edges . since @xmath628 , there is a hamiltonian path @xmath284 in @xmath597 that joins @xmath285 and @xmath286 for @xmath583 . thus , the cycle @xmath633 ( see figure [ appendix ] ( e ) ) is the desired cycle . * subcase 2.1.3 : * @xmath634 . we can represent @xmath610 as @xmath635 . since @xmath614 , we can see that there is an edge @xmath602 in @xmath603 such that @xmath16 ( resp . , @xmath17 ) is incident with a fault - free @xmath245-dimension edge . without loss of generality , we can assume that @xmath604 and @xmath636 are fault - free @xmath124-dimension edges . let @xmath637 and @xmath480 be the faulty edge in @xmath638 . since @xmath255 , @xmath589 ( resp . , @xmath590 ) is incident with a fault - free @xmath124-dimension edge @xmath316 ( resp . , @xmath337 ) . note that @xmath639 . there is a hamiltonian path @xmath284 in @xmath607 that joins @xmath285 and @xmath286 for @xmath351 . thus , the cycle @xmath629 ( see figure [ appendix ] ( f ) ) is the desired cycle . , title="fig:",scaledwidth=80.0% ] + , title="fig:",scaledwidth=80.0% ] + * subcase 2.2 : * @xmath609 . without loss of generality , we can assume that @xmath640 . * subcase 2.2.1 : * @xmath616(or @xmath621 ) . suppose that @xmath641 . * subcase 2.2.1.1 : * @xmath642 is a faulty edge , where @xmath643 . without loss of generality , we can assume that @xmath644 . since @xmath625 , @xmath313 is incident with a fault - free @xmath124-dimension edge , say , @xmath275 . let @xmath617 and @xmath283 be fault - free @xmath124-dimension edges . note that @xmath619 . there is a hamiltonian path @xmath284 of @xmath607 that joins @xmath285 and @xmath286 for @xmath287 . thus , the cycle @xmath544 ( see figure [ appendix ] ( g ) ) is the desired cycle . * subcase 2.1.1.2 : * @xmath645 is a faulty edge where @xmath643 . without loss of generality , we can assume that @xmath646 . \(a ) suppose that each vertex in @xmath51 is incident with at least one fault - free @xmath124-dimension edge . then , there are two disjoint fault - free @xmath124-dimension edges between @xmath607 and @xmath647 for all @xmath287 , namely @xmath435 for @xmath287 . since @xmath648 and @xmath649 , @xmath650 or @xmath558 is a fault - free @xmath124-dimension edge . if @xmath651 , the cycle @xmath652 ( see figure [ appendix ] ( h ) ) is the desired cycle . if @xmath653 , the cycle @xmath654 ( see figure [ appendix ] ( i ) ) is the desired cycle . \(b ) suppose that there is a vertex @xmath17 such that @xmath17 is incident with two faulty @xmath124-dimension edges . without loss of generality , we can let @xmath655 . then , the cycle @xmath656 @xmath657 ( see figure [ appendix ] ( j ) ) is the desired cycle . * subcase 2.2.2 : * @xmath634(or @xmath622 ) . let @xmath480 be the faulty edge in @xmath638 . since @xmath625 , @xmath589 ( resp . , @xmath590 ) is incident with a fault - free @xmath124-dimension edge @xmath316 ( resp . , @xmath337 ) . since @xmath658 , there is a fault - free @xmath124-dimension edge incident with @xmath313 or @xmath314 . without loss of generality , we can assume that @xmath275 is a fault - free @xmath124-dimension edge . let @xmath659 for @xmath60 . then , the cycle @xmath544 ( see figure [ appendix ] ( k ) ) is the desired cycle . in this paper , we consider the problem proposed by zhou @xcite and show that each fault - free edge lies on a fault - free hamiltonian cycle after no more than @xmath2 faulty edges occur when each vertex is incident with at least two fault - free edges . our result is optimal because there is a counterexample when @xmath660 as follows . let @xmath661 and @xmath662 . then , @xmath660 . suppose that there is a hamiltonian cycle @xmath25 . note that @xmath663 . then , @xmath25 contains @xmath664 . note that @xmath665 is a cycle of length @xmath37 , which is a contradiction . thus , there is no hamiltonian cycle in @xmath259 . this research is supported by the national natural science foundation of china ( 11571044 , 61373021 ) , the fundamental research funds for the central university of china . du , edge - fault - tolerant properties of hypercubes and folded hypercubes . _ australasian j. combinatorics _ 35 ( 2006 ) 7 - 16 . ma , a survey on cycle and path embedding in some networks . _ frontiers of mathematics in china _ , 4 ( 2 ) ( 2009 ) , 217 - 252 .

the balanced hypercube , @xmath0 , is a variant of hypercube @xmath1 . zhou et al . [ inform . sci . 300 ( 2015 ) 20 - 27 ] proposed an interesting problem that whether there is a fault - free hamiltonian cycle in @xmath0 with each vertex incident to at least two fault - free edges . in this paper , we consider this problem and show that each fault - free edge lies on a fault - free hamiltonian cycle in @xmath0 after no more than @xmath2 faulty edges occur if each vertex is incident with at least two fault - free edges for all @xmath3 . our result is optimal with respect to the maximum number of tolerated edge faults . _ key words : _ balanced hypercubes ; hypercubes ; hamiltonian cycles ; fault - tolerance .

in low - dimensional electron systems @xcite the quantization of conductance @xcite is observed . for constrictions in two - dimensional electron gases the conductance adopts multiples of the conductance quantum @xmath0 because the transverse wave numbers determine how many modes contribute @xcite . single - atomic size contacts exhibit typical , reproducible and material dependent conductances , which , however , in general are no integer multiples of @xmath1 @xcite . the conductance is associated to an ensemble of transport channels , the number of which corresponds to the number of valence orbitals of the element used . the individual channel transmissions in the range @xmath2 reflect the wave - function overlap from the central to neighbouring and following atoms @xcite . although atomistic ab initio calculations greatly complement experiments in this field , they are not needed to deduce transport channels and their transmissions from measurements . the description using an ensemble of transport channels is a more general concept applicable to any sort of point contact @xcite . the contact - including leads to bulk electrodes - can be viewed as a black box that behaves like the associated ensemble of transport channels . a deeper interpretation of the channels is not required . we shortly review here , in our own way , the theoretical construction behind the description of a single contact in terms of a channel ensemble , because this basis is needed for generalizing the concept to the double junction . regarding the left and right side of a point contact as in fig.1a at first as uncoupled reservoirs let there be a finite number of orthonormal modes on each side ( 2 on the left and 3 on the right as depicted in fig.1b , for example ) . these may be localized atomic orbitals or band modes of a solid crystal . ( small letters @xmath3 and @xmath4 are used here just to distinguish the single from the double junction . ) putting the left and right side together , scattering is determined by some complex amplitudes @xmath5 gathered into matrix @xmath6 ( fig.1c ) . the case that some modes may not couple is included . some entries @xmath5 may be zero . reverse scattering is given by the adjoint matrix ( fig.1d ) . not every matrix with as many lines as there are modes on one side and as many columns as there are modes on the other side can be a scattering matrix @xmath6 , though . probability conservation sets upper limits on the entries . a mandatory limit is , of course , that the absolute value of each entry be lower than or equal to 1 , @xmath7 for all @xmath8 . but then one could think at first glance that it would be sufficient to demand that a particle occupying a pure mode on one side after being scattered to the other side should not cause a probability exceeding 1 there , that is @xmath9 and then the other way round @xmath10 for every @xmath11 . an example showing that this is insufficient will be given in section 4 . for independent transport channels we want an input on the left to come back into the same eigenmode it came from there after having been scattered to the right and back . all further multiple reflections will then stay in this mode . the channels will therefore be determined by diagonalizing @xmath12 . by construction @xmath12 is a hermitian matrix and thus has real eigenvalues . to ensure that the total probability does not increase it is required that any superposition of modes on the left described by a normalized distribution vector when scattered to the right and back is projected onto a mode distribution with total probability less than or at most 1 again on the left . the same , of course , has to hold true for starting with a normalized vector on the right and regarding the probability returning from one backreflection to the left . we shall show that the prohibition of probability creation in forth- and backreflections is equivalent to all eigenvalues of @xmath12 being less or equal to one . all eigenvalues of @xmath12 @xmath13 1 is not a property to deduce of a scattering matrix @xmath6 , but the definition to put for calling a matrix @xmath6 a scattering matrix . in contrast to the usual scattering formalism @xcite we do not distinguish incoming and outgoing modes here . furthermore instead of two transmission and two reflection quadrants our _ scattering matrix _ @xmath6 only consists of one transmission block and only describes transmission from one side of the contact to the other , and therefore does not have to be square . the term _ modes _ or _ original modes _ is used for states that conveniently describe the left and right side of the contact , which can be taken from the situation before a contact is established . we avoid the word channel for these , which is often used synonymous with incoming and outgoing modes @xcite because it is implied differently in the experiment - related description of atomic contacts @xcite . we call _ eigenmodes _ or _ new modes _ those linear combinations of original modes that constitute eigenvectors of @xmath12 or @xmath14 . eigenmodes on the left and the right side of a contact are associated to each other one to one and their connections are called _ transport channels _ or simply _ channels_. let @xmath15 denote the entries of the matrix @xmath16 such that each column of @xmath16 is a normalized eigenvector of @xmath12 . eigenvectors associated to eigenvalues zero have to be kept , and in case of degenerate eigenvalues choose a set of orthogonal eigenvectors associated to them . @xmath16 is a square matrix with the dimension the number of modes on the left . the orthonormality of the eigenvectors is expressed through @xmath17 any normalized input state on the left given by a distribution vector @xmath18 in the basis of the original modes can be converted into the basis of eigenvectors , where we shall call this same vector @xmath19 . @xmath16 is invertable . @xmath20 or @xmath21 . from @xmath22 it easily follows that also @xmath23 and vice versa . the following calculation shows the above claimed equivalance about @xmath6 being a scattering matrix : @xmath24 @xmath25 expresses that the @xmath26th column of @xmath16 is the eigenvector corresponding to eigenvalue @xmath27 . of course , @xmath28 , because eigenvalues are real , and ( 1 ) has been used . some normalized vector @xmath18 or equivalently any normalized vector @xmath19 can arbitrarily be chosen . @xmath19 could especially be a vector with any one component equal to 1 and all other components 0 . then obviously @xmath29 for every @xmath26 individually . to initialize the above calculation from the last line , suppose that every @xmath30 is smaller or equal to 1 . then , for a general @xmath19 , ( 2 ) simply means weighing each term in the sum @xmath31 by a factor @xmath32 , which must give a result @xmath33 . having obtained the scattering amplitudes from a microscopic physical model should ensure @xmath6 being a scattering matrix and all eigenvalues of @xmath12 less or equal to 1 . however , and also because of the need to make up number examples here , an easier criterion than calculating all eigenvalues of @xmath12 would be helpful . @xmath34 is a sufficient condition , although not a necessary one . as a further important aspect one may wonder whether defining transport channels as ( eigen-)modes from the right being backscattered only into themselves would have made a difference from having required this property for ( eigen-)modes on the left . this would mean looking for the eigenvalues and eigenvectors of @xmath14 . as @xmath14 may have a different dimension from @xmath12 , one of these matrices may have more eigenvalues than the other one . the conjecture , that one might get a greater number of transport channels as well as channels with different transmissions with an ansatz looking at backscattering from one side instead of from the other , however , is wrong . we shall now demonstrate that , if @xmath14 is of greater dimension than @xmath12 , @xmath14 has all eigenvalues that @xmath12 has and all its remaining additional eigenvalues are zero . note again that columns of @xmath16 are the eigenvectors of @xmath12 : @xmath35 @xmath36 is the diagonal matrix containing the eigenvalues of @xmath12 in the order of the columns of @xmath16 . to get each column vector of @xmath16 multiplied by the respective @xmath27 , @xmath36 has to be multiplied to @xmath16 from the right . @xmath12 , @xmath16 and @xmath36 are all square matrices with dimension the number of modes @xmath37 on the left side . now multiply ( 4 ) by @xmath6 from the left and as matrix multiplication is associative , we can view that as @xmath38 ( 5 ) tells us that the columns of @xmath39 are eigenvectors of @xmath14 - though not necessarily normalized - with the entries of @xmath36 as associated eigenvalues . @xmath14 is a square matrix with dimension the number of modes @xmath40 on the right side . @xmath6 as well as @xmath39 has @xmath40 lines and @xmath37 columns . single upper indices in ( 4 ) and ( 5 ) denote the dimension of a square matrix , double upper indices the line and column number of a rectangular matrix . every eigenvalue @xmath27 of @xmath12 is an eigenvalue of @xmath14 , too . however , we have not yet specified which number of modes , @xmath37 or @xmath40 , is the greater . for equal mode numbers @xmath41 we have just proven that the sets of eigenvalues of @xmath12 and @xmath14 are identical . now firstly suppose that @xmath42 . then ( 5 ) is a statement about @xmath37 out of the @xmath40 eigenvalues and eigenvectors of @xmath14 , and gives no information about the other @xmath40-@xmath37 . secondly suppose that @xmath43 . as a preparation for the following argument we show that the scalar product of any two different columns of @xmath39 vanishes . elements of ( 4 ) multiplied by @xmath44 from the left give exactly those scalar products . @xmath44 is the matrix with the complex conjugates of the eigenvectors of @xmath12 as lines , or @xmath45 . @xmath15 as before refers to the entries of @xmath16 . @xmath46 @xmath39 has @xmath37 columns , each of which is an @xmath40-vector . in an @xmath40-dimensional vector space there can , however , only be @xmath40 non - vanishing mutually orthogonal vectors . to fulfill ( 6 ) the remaining @xmath37-@xmath40 column vectors must be the zero vector . with more modes on the left than the right there are necessarily some modes or linear combinations of modes on the left that do not get transmitted through the junction at all . now in ( 6 ) choose @xmath47 and @xmath48 one of those column numbers for which @xmath49 is zero for all @xmath50 . then it follows that the corresponding @xmath51 , which is an eigenvalue of @xmath12 , is zero as well . for the single junction diagonalizing @xmath12 or @xmath14 will lead to the same ensemble of transport channels . for illustration an example with numbers is given in section 4 . regarding the first and last expression in the equation for @xmath52 , ( 6 ) also tells us that each @xmath51 represents the sum of some absolute values squared . therefore by its special contruction @xmath12 not only is a hermitian matrix with real eigenvalues , but all eigenvalues are even greater or equal to zero . this is essential because we shall identify the square roots of the @xmath27 as phaseless transmission amplitudes @xmath53 . properties of a series of two junctions will initially be given in terms of two scattering matrices , one between reservoirs l(left ) and i(island ) , and one between reservoirs i and r(right ) ( fig.3a ) . multiplying each scattering matrix by its adjoint and diagonalizing would give transport channel ensembles for each junction separately and represent the setup for incoherent coupling @xcite across the island . there are multiple reflections in each junction , but a charge transported to the island not to go back through that same junction relaxes there , that is changes the island s electrostatic potential , however , looses the information which ( eigen-)mode it had come into . diagonalizing matrices for each junction separately will not lead to the same linear combinations of island modes as eigenmodes for each side . setting up our formalism to determine transport channels with coherent coupling between two the junctions is not obvious , should just any of the three reservoirs l , i , r be chosen to demand that eigenmodes there associated to channels exclusively return to themselves if transmitted away from that reservoir and backscattered into it . nevertheless , as a scattering process starting on the island after two scattering steps offers no other possibility than to have brought the charge carrier back to the island , the above requirement _ for the island _ provides a promising ansatz . therefore given scattering matrices from i to l and from i to r , with by definition the same number of i - modes , are just joint together into one scattering matrix @xmath6 by taking all rows together . @xmath6 and @xmath54 are formally given with exemplary numbers of modes three on the left , four on the island and two on the right in fig.2 ( fig.3 are drawn for different numbers ) . now @xmath12 is diagonalized , again denoting eigenvalues as @xmath27 and eigenvectors as @xmath16 . the column vectors from @xmath16 build linear combinations of the original island modes . eigenvectors of @xmath14 , however , given by @xmath39 , now combine modes from both leads l and r. a @xmath55 associated to an eigenvector out of @xmath16 or the corresponding vector from @xmath39 gives us the transmission amplitude of a combined channel between the island and the entire outside world consisting of both leads . if there have been @xmath56 original modes at l and @xmath57 at r , every column of @xmath58 is a normalized vector of length @xmath56+@xmath57 , whose first @xmath56 components represent coefficients for l - modes and whose last @xmath57 components are coefficients for r - modes . however , like for the single junction case , modes at l and r are independent . supplying a charge carrier in an original mode on the left , for example , makes the transmission eigenmodes it contributes to be populated with percentages the absolute values squared of their coefficients in the respective column from @xmath59 . therefore the transmission of an above mentioned combined channel splits up into the probability percentages left and right side modes contribute to the respective eigenmode . for assigning transmission amplitudes we take the roots of these parts to be multiplied by @xmath55 . so for the transmission amplitudes @xmath60 and @xmath61 for the left and right side channels of a pair of channels coherently linked together on the island ( = combined channel ) we obtain @xmath62 and @xmath63 this construction demonstrates that a series of point contacts enclosing a bulk - like island even with coherent coupling across the latter is _ not _ equivalent simply to a number of effective transport channels from left to right . paths from left to right rest a channel through the left junction connected to a channel through the right junction and these two parts can have different transmissions . however , we can not expect to describe coherently coupled junctions by the channel ensembles each one would exhibit as a single junction . furthermore , by construction there is no coherent cross coupling on the island between our newly found channels . one channel from the left can only be coherently coupled to one channel from the right and vice versa ( fig.3b ) . this finding elegantly solves the problem of generalizing a green s functions method for modelling current - voltage characteristics in the coherent case @xcite to several channels per junction . the algorithm to calculate changing rates for the island charge is only needed for a single channel per junction . contributions from all pairs of channels can then simply be added in classical rate equations . there may also be channels in a junction not coherently coupled to a partner channel in the other junction ( or pairs with transmission amplitude zero in one half ) . their island charging rates are even easier to calculate @xcite . we should only expect such unpaired channels , however , if in the original pattern there are modes coupled across one junction that are totally decoupled from all others involved in a network of couplings over both junctions , like l3 and i5 in fig.3a . i4 is not directly coupled to l , however indirectly via r3 and i3 as well as other paths , and will thus contribute to eigenmodes involving connections to both leads . like in the single junction case , there may be specific linear combinations of original modes at every one of the three sites that are not transmitted at all . for a consistent description of the double junction with coherent coupling across the island , it has to be required that @xmath64 with the normalized vector @xmath18 representing any linear combination of original modes on the island and @xmath6 and @xmath54 now the big matrices from fig.2 . the prohibition of probability creation here also implies that all eigenvalues @xmath27 of @xmath12 have to be less than or at most one , even if the transmissions assigned to the channels in each junction further get multiplied with the parts by which a new combined island mode is transferred to each side . the new left and right modes at the ends of a pair of channels in fact constitute only parts of new combined - lead modes . the latter , however , form a unique set of eigenmodes . all these considerations about the double junction will be illustrated by number examples in the next section . we shall here present some further more marginal considerations on probability conservation or prohibiting probability creation . at the beginning of our analysis we regarded the system as described by an orthogonal set of modes on the left , an orthogonal set on the island and an orthogonal set on the right . of course , with the contact established overlaps exist between modes in a lead and modes on the island . these determine the transition amplitudes put into the original scattering matrix . the overlaps should , however , only go so far that parts of an island wave function that couple to left wave functions rest well separated from parts that couple to the right . then the sum of absolute squares of all scattering matrix elements out of an island mode will in no case exceed unity . the orthogonality of the modes in one lead ensures that the sum of absolute squares of all couplings to one certain island mode is limited by the norm one of that mode . taking just any overlaps that could have been set up as single junction scattering amplitudes does not automatically guarantee that the norm of any column vector of the big matrix @xmath6 , which contains scattering to the left _ and _ right modes , is less or equal to one . if the intersection of the overlaps of an island wave function with left wave functions and that with right wave functions is not empty , there would be a direct overlap between left and right wave functions , which will give rise to a direct transport channel from left to right . such a situation could be realizable , but our model does not cover that . nevertheless , suppose that two junctions in series have been investigated with incoherent coupling @xcite . in the incoherent model changes of the island charge and thus potential are felt by both contacts , but otherwise the latter are independent and behave like a single junction each . with incoherent coupling the regarded set of island modes need not even be the same concerning transport through the left or the right junction , but here suppose it is . to compare with the incoherent behaviour , one might want to estimate the system s properties if the same junctions get linked together coherently ( without allowing for direct left - to - right channels ) and therefore just put together two single - junction scattering matrices @xmath65 and @xmath66 into one like in fig.2a . where this should result in a column norm of @xmath6 exceeding unity , in this situation it makes sense to renormalize scattering amplitudes in the way that of the island mode the part overlapping with both left and right wave functions is scattered to either side with probabilities proportional to the ratio of absolute squares of the single - junction scattering amplitudes . in any case put - together scattering matrices @xmath6 should be checked for no column norm exceeding unity prior to solving for transport channels . let us illustrate that the simple criterion of norms of lines or columns being less or equal to 1 is not sufficient to ensure that a matrix is a scattering matrix . for simplicity an example with purely real numbers is given . for the single junction let @xmath54 be @xmath67 supposing two modes on the left and four on the right . then @xmath68 are all less than 1 . @xmath69 the eigenvalues of this matrix , namely the solutions of @xmath70 however , are @xmath71=0.148 and @xmath72=1.652 ( rounded to 3 digits ) , of which @xmath72 clearly is greater than 1 . ( 3 ) is not fulfilled : @xmath73 let us now regard @xmath74 which is a scattering matrix , but otherwise its complex entries are randomly chosen . as @xmath6 is 3x2 , there are two original modes on the left and three on the right . @xmath75 and the eigenvalues of this 2x2 square matrix are @xmath71=0.1421 and @xmath72=0.2904 . @xmath76 is a 3x3 square matrix with eigenvalues @xmath71=0.1421 , @xmath72=0.2904 and @xmath77=0 ( a numerical calculation gives @xmath78 ) . to check ( 3 ) for both @xmath12 and @xmath14 we calculate @xmath79 by the way , the same value is obtained as @xmath80 with complex numbers even normalized eigenvectors are only determined up to a phase common to all components . the numerical routine we used to evaluate them gave them with real last component . for @xmath12 they are @xmath81 associated to @xmath71 and @xmath72 , respectively . eigenvectors of @xmath14 are @xmath82 associated to eigenvalues zero , @xmath71 and @xmath72 in that order . by multiplying ( 5 ) by @xmath83 from the left , one deduces that the factor needed to normalize a column vector of @xmath39 , which we showed to be an eigenvector of @xmath14 , is @xmath84 with @xmath27 the corresponding eigenvalue . we shall now check explicitly the relation between the two sets of eigenvectors in our example , and especially verify that for unequal mode numbers left and right , the transformation in one direction produces some zero vector . @xmath85 @xmath86 @xmath87 @xmath88 @xmath89 @xmath90 @xmath87 the last is the zero vector within the accuracy taking into account no more than the written digits . it can not be normalized , of course , hence there is no factor @xmath84 in the last line . entries of scattering matrices are in general complex , but for simplicity we give examples with real numbers for the double junction , which is totally sufficient to show the important aspects of the calculation . to better keep track of which scattering amplitudes belong to the left and the right junction , @xmath6 is noted in table form like in fig.2 . our first example has four modes on the island , two in each lead and no vanishing scattering amplitudes . @xmath91 the sum of squares of all these 16 elements is 0.9921 , which is less than 1 and should thus ensure that all eigenvalues will be less than or at most 1 . the matrix to diagonalize is @xmath92 as eigenvalues and associated eigenvectors one finds @xmath6 times the matrix made of these four column vectors returns a matrix consisting of the following four column vectors : \(25 ) gives the normalized eigenvectors of @xmath12 given in the basis of the original island modes , which is hinted at by the labels @xmath93 in front of their components . ( 26 ) lists eigenvectors of @xmath14 and their components refer to the basis of lead modes . vectors in ( 26 ) are not yet normalized . to do so , divide by the square root of the @xmath27 above the respective column from ( 25 ) . to fully link the number examples to the notation of the previous sections , remark that the vectors in ( 25 ) give the columns of @xmath16 and those in ( 26 ) constitute @xmath39 . obviously the eigenchannel system consists of four pairs of channels , denoted as @xmath94 , @xmath95 . with the values from ( 26 ) we shall now work out the left and right contributions in each . for example , the transmission amplitude of the left channel in the first pair is given by the part of the l - modes in the normalized eigenvector multiplied by the square root of the respective @xmath27 , which is the transmission amplitude of the island eigenmode to the entire outside world , @xmath96 . the reason to give non - normalized vectors in ( 26 ) was that explicit factors @xmath55 drop out here . the following table lists all left and right transmission amplitudes as determined by ( 7 ) and ( 8) : [ cols="^,^,^,^,^ " , ] here again , the maximum possible input left amounts to two modes , and that right to one : @xmath97 channels are not at all the same as when letting the @xmath98-mode being transported fully coherently across the island . the important finding is , however , that , even if by construction some of the original island modes only have a direct overlap with one lead , the eigenchannel ensemble does not contain channels merely bridging a single junction ( if no paths are totally separated from the rest of the original network ) . the connection of the coherently and incoherently transported island modes via the lead modes causes the system to appear as effectively consisting of fully coherently linked channel pairs . as already pointed out earlier , the system of channel pairs does not suppress sequential transport . the latter may well be found to provide the dominating contributions in current - voltage characteristics . the channels with the largest throughput left and right may form a pair , in principle , however , as well belong to different pairs . can not be inferred from single @xmath53 alone . a renormalization is analytically possible in the normal conducting case , and a channel on the left , for example , would get @xmath99 @xcite . ] it has been discussed how to determine the ensemble of transport channels for a series of two point contacts enclosing an island between them , which allows coherent transport across it . we find that transport channels are only coherently coupled together in pairs involving one channel per junction . this makes a green s functions algorithm developed for single - channel junctions coherently coupled via an island @xcite applicable to the general case of multichannel junctions . the channel ensembles describing coherently coupled contacts will differ from those describing the same contacts each taken as a stand - alone device . partially coherent transport across the island can also be treated with the presented method of determining transport channels and will effectively look like coherent transport through more but less open channels . circuits with more than two contacts in series or with short - cutting channels between leads , however , would be more complicated to handle . van wees b j , van houten h , beenakker c w j , williamson j g and foxon c t 1988 _ phys.rev.lett . _ * 60 * 848 ; crook r , prance j , thomas k j , chorley s j , farrer i , ritchie d a , pepper m and smith c g 2006 _ science _ * 312 * 135 . there are deviations from integer conductances in long junctions : gloos k , utko p , aagesen m , srensen c b , bindslev hansen j and lindelof p e 2006 _ phys.rev.b _ * 73 * 125326 . and anomalies due to spin - splitting : bychkov a m and stace t m 2007 _ nanotechnolgy _ * 18 * 185403 . refer to metallic single - electron transistors , however , contacts there are tunnel junctions . for example : hadley p , delvigne e , visscher e h , lhteenmki s and mooij j e 1998 _ phys.rev.b _ * 58 * 15317 ; hergenrother j m , tuominen m t and tinkham m 1994 _ phys.rev.lett . _ * 72 * 1742 ; billangeon p m , pierre f , bouchiat h and deblock r 2007 _ phys.rev.lett . _ * 98 * 216802 .

transport through a point contact is accurately modelled by assigning to the junction an ensemble of independent transport channels with possibly different transmissions . we here argue that for a series of two contacts , coherently coupled across an island , the transport channels are different from the ensembles that would describe each contact taken as stand - alone device . we further show that instead of two sets of channels with manifold cross - links over the island the double junction can be described by pairs of channels from both sides coherently coupled together , where each pair , however , has no coherent connection to the others . this finding will substantially simplify modelling transport by a green s functions technique . additional channels through only one junction may complete the picture . finally we discuss how partial coherence across the island with an appropriate ansatz can be modelled in the same scheme .

bone is a highly dynamic tissue that undergoes continuous remodeling , which is regulated by various factors , including cytokines / chemokines , hormones , and mechanical stimuli . under normal conditions , bone homeostasis is controlled by the balance between bone formation and bone resorption , processes regulated by osteoblasts and osteoclasts , respectively . however , excessive bone resorption by osteoclasts compared to bone formation by osteoblasts , results in osteopenic disorders such as osteoporosis , rheumatoid arthritis , paget 's disease , and lytic bone metastases of malignancies . osteoclast precursor cells of monocyte - macrophage lineage fuse to form tartrate - resistant acid phosphatase ( trap)-positive multinucleated cells . the multinucleated osteoclasts reorganize the actin cytoskeleton to attach to the bone surface and to resorb the bone . osteoclast differentiation is regulated by two essential cytokines , macrophage colony - stimulating factor ( m - csf ) and receptor activator of nuclear factor - kappa b ( nf-b ) ligand ( rankl ) . m - csf is considered a crucial factor responsible for the survival and proliferation of osteoclast precursor cells . it also induces receptor activator of nf-b ( rank ) expression in osteoclast precursor cells to evoke efficient response to the rankl - rank signaling pathways . rankl mediates biological effects in bone through its sole receptor , rank . binding of rankl to rank receptor results in the recruitment of tumor necrosis factor ( tnf ) receptor - associated factor 6 ( traf6 ) , which is involved in the activation of downstream signaling pathways , such as nf-b , c - jun n - terminal kinase ( jnk ) , p38 , and extracellular signal - regulated kinase ( erk ) pathways . in addition , rankl activates various transcription factors such as nf-b , microphthalmia transcription factor ( mitf ) , c - fos , and nuclear factor - activated t cells c1 ( nfatc1 ) , which are responsible for osteoclast differentiation . in particular , nfatc1 , a master regulator of osteoclast differentiation , regulates a number of osteoclast specific genes such as trap , cathepsin k , calcitonin receptor , and osteoclast - associated receptor ( oscar ) through cooperation with mitf and c - fos . the essential role of nfatc1 in osteoclast differentiation has been well established by several studies performed on genetically modified mutant mice . a transgenic mouse strain was generated by winslow et al . by crossing nfatc1-knockout mice with mice expressing tie2-promoter - driven nfatc1 in order to overcome a defect in cardiac valve formation in nfatc1-knockout mice . these transgenic mice are viable and exhibit an osteopetrotic bone phenotype owing to a severe defect in the osteoclastogenesis process . another report states that osteoclast - specific conditional nfatc1-deficient mice develop osteopetrosis owing to impaired osteoclastogenesis . however , the ectopic expression of nfatc1 in osteoclast precursor cells induces osteoclast differentiation in these cells despite the absence of rankl . these results clearly indicate that nfatc1 is an indispensable factor for osteoclast differentiation in vitro and in vivo . therefore , understanding the molecular mechanisms underlying the regulation of nfatc1 in osteoclasts may provide novel therapeutic strategies for bone diseases associated with excessive osteoclast differentiation and function . the nfat gene family was originally identified around 25 years ago as a group of transcription factors that could bind to the interleukin 2 ( il-2 ) promoter in activated t cells . since the discovery of the first nfat protein , nfats have been discovered to be involved in immune cell activation , heart valve formation , cardiac hypertrophy , and osteoclast development . however , the function and regulation of nfat proteins is best understood in t cells . the nfat family consists of five members : nfat1 ( also known as nfatp or nfatc2 ) , nfat2 ( also known as nfatc or nfatc1 ) , nfat3 ( also known as nfatc4 ) , nfat4 ( also known as nfatx or nfatc3 ) , and nfat5 . all proteins from the nfat family , excluding nfat5 , are regulated by the calcium signaling pathway . nfat proteins are phosphorylated at the serine residues located in the regulatory domain , and exist in an inactive form in the cytosol in resting t cells . however , the signals induce the release of intracellular ca , which activates calcineurin , a ubiquitous serine - threonine phosphatase , which dephosphorylates nfat proteins . this leads to their translocation from the cytosol to the nucleus , where they regulate the target genes . there is a high degree of structural similarity among the different members of the nfat family , which allows for redundancy in some nfat functions in t cells . knockout mice deficient in individual nfat proteins show only mild changes in immune function ; however , elimination of more than one nfat protein in mice results in severe alterations in the immune system . c - fos , a member of the activator protein-1 ( ap-1 ) family of transcription factors , is induced at an early stage during osteoclast differentiation . c - fos - knockout mice develop osteopetrosis owing to defects in osteoclast lineage commitment . in addition to osteoclast differentiation , the induction of nfatc1 mrna by rankl is also abrogated in c - fos - deficient cells . these defects were corrected by overexpression of nfatc1 in c - fos - deficient cells in vitro . studies have also reported that c - fos is recruited to the nfatc1 promoter at an early stage of osteoclast differentiation . these results suggest that c - fos is an indispensable factor involved in early induction of nfatc1 for osteoclast differentiation ( fig . rankl also rapidly stimulates the activation of classical or alternative nf-b pathway in osteoclast precursor cells . the nf-b family , a group of dimeric transcription factors , consists of five members : crel , rela ( p65 ) , relb , nf-b1 ( p50 ) , and nf-b2 ( p52 ) . in the classical pathway , inhibitor of b ( ib ) kinase ( ikk ) complex phosphorylates and degrades ib . subsequently , the proteasomal degradation of ib induces activation of the p50/rela complex . in the alternative pathway , nf-b - inducing kinase ( nik ) and ikk phosphorylate and process p100 to generate p52 by proteasomes , resulting in the activation of the p52/relb complex . the important role played by nf-b proteins in osteoclastogenesis has been verified by the severe osteopetrotic phenotype observed in p50 and p52 double deficient mice . recently , it has been reported that dehydroxymethylepoxyquinomicin ( dhmeq ) , an nf-b inhibitor , attenuates rankl - induced osteoclastogenesis through down - regulation of nfatc1 . consistent with these results , chip experiments have demonstrated that the nf-b components p50 and p65 are recruited to the nfatc1 promoter 1 hr after rankl stimulation . although it is unclear whether the classical or alternative nf-b pathway is dominant in osteoclast differentiation , it is certain that the nf-b components p50 and p65 are important for the initial induction of nfatc1 during rankl - induced osteoclastogenesis ( fig . 1 ) . the nfat protein family plays a redundant role in the immune system . nfatc1 and nfatc2 , closely related due to the similarity in their dna binding domains , are expressed in osteoclasts . however , nfatc1-deficient mice exhibit a severe osteopetrotic phenotype , while nfatc2-deficient mice show normal skeletal development . to investigate the unexpected non - redundant role played by nfatc1 in the skeletal system , asagiri et al . the defect in osteoclast formation by nfatc1-deficient osteoclast precursor cells is recovered by overexpression of nfatc1 and nfatc2 . they also established that fk506 , an inhibitor of nfat activity , suppresses mrna expression of nfatc1 but not of nfatc2 . chip experiments revealed that nfatc1 is consistently recruited to the nfatc1 promoter , but not the nfatc2 promoter , during the terminal differentiation of osteoclast . therefore , nfatc1 is suggested to be a unique nfat protein , which is regulated at the transcriptional level through an autoregulatory loop during osteoclast differentiation . interestingly , nfat - binding sites exist in nfatc2 as well as nfatc1 promoters . during osteoclast differentiation , transcriptional coactivators with histone acetylase activity , including the cyclic adenosine 3',5'-monophosphate ( camp ) response element - binding protein ( creb)-binding protein ( cbp ) and p300/cbp - associated factor ( pcaf ) , are recruited to nfatc1 promoters but not nfatc2 promoters . in addition , histone deacetylase 1 ( hdac1 ) gradually dissociates from nfatc1 promoters as the osteoclasts differentiate . therefore , the exclusive autoamplification of nfatc1 in osteoclasts is supported by epigenetic regulation of the nfatc1 promoters . in conclusion , the induction of high levels of nfatc1 transcriptional factor by rankl induces the self - sustaining positive autoregulatory system to maintain sufficient nfatc1 expression and osteoclast differentiation ( fig . 1 ) . as nfatc1 is a master transcriptional factor for osteoclast differentiation , our research , as well as that of others , was focused on finding the negative regulators of nfatc1 in osteoclasts . our research has indicated that rankl attenuates expression of the inhibitors of differentiation ( ids ) , v - maf musculoaponeurotic fibrosarcoma oncogene homolog b ( mafb ) , and lim homeobox 2 ( lhx2 ) , which act as negative regulators of osteoclastogenesis by downregulating the expression of nfatc1 ( fig . 1 ) . we have also found that protein inhibitor of activated stat3 ( pias3 ) inhibits rankl - mediated transcription of nfatc1 ( fig . interferon regulatory factor-8 ( irf-8 ) and b - cell cll / lymphoma 6 ( bcl-6 ) have also been identified as negative regulators of nfatc1 . rankl inhibits the expression irf-8 during osteoclastogenesis , and the overexpression of irf-8 blocks rankl - induced osteoclast differentiation . 1 ) . in addition , the deletion of lhx2 , irf-8 , and bcl-6 in mice causes severe osteoporosis . these results demonstrate the importance of multi - pathway regulation of nfatc1 for maintenance of normal bone homeostasis . epigenetics is defined as heritable change in the function of genetic elements without changes in the dna sequence . there are three classes of epigenetic markers , dna methylation , histone modification , and noncoding rnas . these play an important role in the determination of cell fate . among the epigenetic modification methods , generally , hypermethylation of cpg - rich regions in gene promoters blocks gene expression , while hypomethylation stimulates gene expression . recently used chip sequencing technology to demonstrate that histone h3 lysine 4 ( h3k4me3 ) is present in the nfatc1 gene in osteoclast precursor cells , but is markedly reduced in mature osteoclasts . during osteoclastogenesis , expression and recruitment of jumonji domain - containing protein 3 ( jmjd3 ) , a h3k27 demethylase , around the transcription start site of nfatc1 in addition , the down - regulation of jmjd3 by using short hairpin rna , inhibits demethylation of h3k27me3 at the transcription start site of nfatc1 ; thereby suppressing rankl - induced osteoclast differentiation . these results raise the possibility that epigenetic regulation of nfatc1 by the mechanism underlining methylation or demethylation is essential for rankl - induced osteoclast differentiation . post - translational modification such as ubiquitination and acetylation are important mechanisms of gene regulation . our previous studies have indicated that the stability of nfatc1 proteins is controlled by ubiquitination and acetylation during osteoclast differentiation ( fig . nfatc1 proteins are downregulated by m - csf during late stage osteoclastogenesis , and subsequently degraded through the ubiquitin - proteasome pathway in the cytoplasm . in addition , nfatc1 interacts endogenously with c - src , c - cbl , and cbl - b in the osteoclasts . overexpression of c - src induces down - regulation of nfatc1 , and depletion of the cbl proteins blocks nfatc1 degradation during late stage osteoclastogenesis . these results suggest that m - csf induces nfatc1 ubiquitination and degradation via cbl proteins in a src kinase dependent method during late stage osteoclastogenesis . therefore , our previous research data suggest a negative regulatory mechanism through ubiquitination of nfatc1 , mediated by m - csf signaling pathway , in osteoclast differentiation ( fig . we demonstrated that rankl could induce the accumulation of nfatc1 , which is regulated by acetylation of the nfatc1 protein via a transcription - independent mechanism . nfatc1 acetylation is mediated by histone acetyltransferase ( hat ) activity of pcaf through physical interaction with nfatc1 . because acetylation of many proteins is a reversible post - translational modification , we have identified which hdac can inhibit lysine acetylation by removal of the acetyl group from the nfatc1 . in addition , hdac5 reduces the stability and transactivation of nfatc1 , thereby attenuating rankl - induced osteoclast differentiation ( fig . 2 ) . therefore , our study proves that m - csf and rankl , two essential cytokines , induce ubiquitination and acetylation of nfatc1 respectively , to control osteoclast differentiation , by modulating nfatc1 stability and activity . mirnas are short non - coding rnas , approximately 22 nucleotides in length , that regulate diverse biological processes , including proliferation , apoptosis , and differentiation , through post - transcriptional regulation . generally , mirnas act as direct negative regulators of gene expression that bind to the specific sequence at the 3 ' untranslated region ( utr ) of the target mrna . the mirna biogenesis pathway has multiple steps : transcription , pri - mirna processing , transport to the cytoplasm , precursor mirna processing , strand selection , target transcription , and fate transcription . 2 ) . with emerging evidence suggesting the involvement of several mirna in osteoclastogenesis , additional studies will be required to find an mirna that can directly regulate nfatc1 expression in osteoclasts it has been substantially demonstrated that nfat proteins are primarily regulated by calcium and calcineurin . rankl activates phospholipase c- ( plc- ) , which hydrolyses phosphatidylinositol-4,5-bisphosphate to generate inositol-1,4,5-trisphosphate ( insp3 ) and diacylglycerol . calcium binds to calmodulin , which in turn activates the calmodulin - dependent phosphatase calcineurin . dephosphorylation of serine residues in nfatc1 by activated calcineurin leads to nuclear translocation , and activation of nfatc1 proteins . targeted deletion of plc-2 in mice results in an osteopetrotic phenotype , and the osteoclast precursor cells lacking plc-2 do not sufficiently induce nfatc1 expression even in the presence of rankl . well known inhibitors of calcineurin , such as fk506 and cyclosporine a , strongly inhibit rankl - induced osteoclast differentiation by blocking nfatc1 translocation into the nucleus in vitro and in vivo . in addition , the ca chelator bapta - am suppresses osteoclast differentiation mediated by rankl through the inhibition of nuclear localization of nfatc1 . these results suggest that the activation of calcium - calcineurin pathway plays a crucial role in the regulation of nfatc1 during osteoclastogenesis . several kinases such as glycogen synthase kinase 3 ( gsk3 ) , casein kinase 1 ( ck1 ) , p38 , and jnk phosphorylate the various serine - rich motifs in nfat proteins , thereby preventing translocation into the nucleus or promoting nuclear export of nfat proteins . a recent study has reported that the ectopic expression of the constitutively active gsk-3 ( gsk3-s9a ) mutant in osteoclast precursor cells inhibits rankl - mediated nfatc1 expression and ca oscillations . have also shown a significant defect in nfatc1 expression and nuclear localization in osteoclast precursor cells isolated from transgenic mice expressing gsk3-s9a mutant . these findings indicate that gsk3 inactivation by rankl is important for the expression and activation of nfatc1 in osteoclasts ( fig . 1 ) . since rank receptor does not seem to directly initiate ca signaling , it has been studied for its role as an immunoreceptor alongside other receptors such as oscar , triggering receptor expressed in myeloid cells-2 ( trem-2 ) , paired immunoglobulin - like receptor - a ( pir - a ) , and signal - regulatory protein 1 ( sirp1 ) in osteoclasts that are involved in calcium signaling in immune cells . the association of immunoreceptors with immunoreceptor tyrosine - based activation motif ( itam)-harboring adaptors has been observed in osteoclast precursor cells : oscar and pir - a are associated with fc receptor common subunit ( fcr ) and trem-2 and sirp1 are associated with dnax - activating protein 12 ( dap12 ) . the association of an immunoreceptor with the itam - harboring adapters , fcr and dap12 , stimulates calcium signaling . although dap12-deficient mice exhibit only mild osteopetrosis , fcr and dap12 double knockout mice ( dap12 fcr ) develop severe osteopetrosis due to defects in osteoclast differentiation . interestingly , the defect in osteoclast differentiation in dap12 fcr cells is fixed by the overexpression of dap12 , but not dap12y65f , which has a mutation in itam , suggesting that the itam - mediated signaling pathway is indispensable for osteoclastogenesis . as expected , ca oscillation and the induction of nfatc1 were also suppressed in dap12 fcr cells , recovered by the overexpression of nfatc1 , but not c - fos or traf6 . these results suggest that the induction and activation of nfatc1 is regulated by calcium signaling pathway , mediated by itam - harboring adapters , fcr and dap12 , in the osteoclasts ( fig . the stimulation of itam - associated receptors alone , without rankl , can not induce osteoclast differentiation , although itam - associated receptors stimulate ca - nfatc1 pathway through itam - harboring adaptors during osteoclastogenesis . therefore , itam - mediated signals may provide costimulatory signals to maximize the induction of nfatc1 for rank . since nfatc1 is indispensable for osteoclast differentiation , future studies based on currently available data about nfatc1 regulation could provide novel therapeutic strategies for bone diseases .

osteoclasts are unique cells that degrade the bone matrix . these large multinucleated cells differentiate from the monocyte / macrophage lineage upon stimulation by two essential cytokines , macrophage colony - stimulating factor ( m - csf ) and receptor activator of nuclear factor - kappa b ( nf-b ) ligand ( rankl ) . activation of transcription factors such as microphthalmia transcription factor ( mitf ) , c - fos , nf-b , and nuclear factor - activated t cells c1 ( nfatc1 ) is required for sufficient osteoclast differentiation . in particular , nfatc1 plays the role of a master transcription regulator of osteoclast differentiation . to date , several mechanisms , including transcription , methylation , ubiquitination , acetylation , and non - coding rnas , have been shown to regulate expression and activation of nfatc1 . in this review , we have summarized the various mechanisms that control nfatc1 regulation during osteoclast differentiation .

These crawls are part of an effort to archive pages as they are created and archive the pages that they refer to. That way, as the pages that are referenced are changed or taken from the web, a link to the version that was live when the page was written will be preserved.Then the Internet Archive hopes that references to these archived pages will be put in place of a link that would be otherwise be broken, or a companion link to allow people to see what was originally intended by a page's authors.The goal is to fix all broken links on the web . Crawls of supported "No More 404" sites. ||||| ... resenting Israel as a Livets Ord bible school student, and now as well, every time I visit Livets Ord I am truly blessed, and I can't wait to participate in Livets Ord bible school myself. Livets Ord is like a second home for me. Since I was little at the Euroconference with my father rep ||||| A drone at a demonstration in Brigham City, Utah, in February, 2014. (Rick Bowmer/AP) "Packed out church tonight as I got to reveal our brand new mission project," the pastor's caption on Instagram said. "@livetsord will start using military drones, three meters wide, to drop thousands of electronic Bibles over closed areas in the Middle East. Let's pray the message of God's love in Christ will conquer that of darkness and hate!" Hmm. The apparent logic of the Swedish church Livets Ord, or "Word of Life," is that by using a tactic that simulates the airstrikes that have traumatized a region, they will bring light and love and maybe convert some Muslims to Christianity. "We start our project in a few weeks and hope to drop thousands of Bibles," the church's website says. The Bibles are "pillbox"-size and will supposedly be dropped from high altitude by a contractor hired by the church. Faced with scorn from the media, Christian Akerhielm, the church's missions director, has emphasized that the drone campaign adds to their good work in the region, which involves distributing aid at refugee camps. "The project has been in the media portrayed as an ‘attack on IS’ or with the terror group as the main target. This is not true," Akerhielm said, referring to the Islamic State. "This mission's project is closer to traditional smuggling of Bibles, and it is not connected to any military or aggressive action in any way." The evangelical church was founded in 1983, and its founders have since left it and converted to Catholicism. It is a massive entity in the city of Uppsala, an hour's drive north of the Swedish capital, Stockholm. It is run by the charismatic preacher Joakim Lundqvist, who introduced the drone mission to church attendees. You had to be there! #LivetsOrd #Ek16 A photo posted by Församlingen Livets Ord (@livetsord) on Jul 30, 2016 at 12:43pm PDT It is unclear whether the church or its contractor would require some kind of security clearance to carry out the airdrops. The Bibles are electronic but don't need to be plugged in to work. One assumes they have been translated into Arabic, but that isn't indicated in any of the publicity around the mission. Read More: Rebel supporters in Aleppo created their own no-fly zone by burning tires An airstrike in Syria killed entire families instead of ISIS fighters When ISIS claims terrorist attacks, it’s worth reading closely

– What people living in ISIS-controlled areas really need is Christianity delivered by drone, an evangelical church in Sweden has decided. The Uppsala-based Word of Life church says it plans to use military drones to drop thousands of Bibles over parts of Syria in the hope of converting Muslims, CNET reports. "Let's pray the message of God's love in Christ will conquer that of darkness and hate," the church said in an Instagram post. The church plans to drop Arabic-language electronic Bibles, which will not need to be plugged in to work. The church's missions director says the plan "is not connected to any military or aggressive action in any way," but has a lot in common with traditional smuggling of Bibles into places like the Soviet Union, the Washington Post reports. On its Facebook page, the church says the Bible drop is happening in parallel with the church's other work in the region, including providing medical care in refugee camps. It hasn't responded to a post from somebody worried that ISIS will harshly punish anybody caught with a Bible—and that extremists will now target the church's headquarters in Sweden.

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in the past decade , an avalanche of findings and reports has correlated arrhythmogenic ventricular cardiomyopathies ( arvc ) and naxos and carvajal diseases with certain mutations in protein constituents of the special junctions connecting the polar regions ( intercalated disks ) of mature mammalian cardiomyocytes . these molecules , apparently together with some specific cytoskeletal proteins , are components of ( or interact with ) composite junctions . composite junctions contain the amalgamated fusion products of the molecules that , in other cell types and tissues , occur in distinct separate junctions , i.e. desmosomes and adherens junctions . as the pertinent literature is still in an expanding phase and is obviously becoming important for various groups of researchers in basic cell and molecular biology , developmental biology , histology , physiology , cardiology , pathology and genetics , the relevant references so far recognized have been collected and are presented here in the following order : desmocollin-2 ( dsc2 , dsc2 ) , desmoglein-2 ( dsg2 , dsg2 ) , desmoplakin ( dp , dsp ) , plakoglobin ( pg , jup ) , plakophilin-2 ( pkp2 , pkp2 ) and some non - desmosomal proteins such as transmembrane protein 43 ( tmem43 ) , ryanodine receptor 2 ( ryr2 ) , desmin , lamins a and c , striatin , titin and transforming growth factor-3 ( tgf3 ) , followed by a collection of animal models and of reviews , commentaries , collections and comparative studies .

it is also called benign mixed tumor of skin as it contains both epithelial and mesenchymal components . the most common presentation is a small , slow - growing , subcutaneous nodular mass in the head - neck region . until now , only few cases of cytological diagnosis of chondroid syringoma have been reported . here , we are presenting a unique case of eccrine chondroid syringoma of forearm , diagnosed by fine - needle aspiration cytology ( fnac ) and subsequently confirmed by histopathology . a 33-year - old male presented with a nodular swelling over left forearm for 1 year . on examination , it was a firm to hard , nontender , mobile , subcutaneous mass measuring 2 cm 1.5 cm . fine - needle aspiration was done with 22 g needle attached with 20 ml disposable syringe . on cytological examination , smears were moderately cellular comprising of clusters of round to oval cells and abundant chondro - myxoid ground substance . the epithelial cells were monomorphic , round to oval , medium sized having moderate amount of cytoplasm , bland round to oval nuclei with finely dispersed chromatin [ figure 1a and b ] . smaller myoepithelial cells having plasmacytoid appearance with dark nuclei were interpreted within clumps of epithelial cells [ figure 1a ] . ( a and b ) smears show tight clusters of benign round to oval epithelial cells and myoepithelial cells in fibrillary chondro - myxoid ground substance ( leishman giemsa stain , 400 ) on excision , the mass was encapsulated , partially covered with skin , firm to hard in consistency and measuring 2 cm 1.5 cm 1 cm . cut surface of the tumor was solid , gray tan in color and without any necrosis or hemorrhage . on histopathological examination , the tumor was encapsulated with a large area of cartilaginous differentiation . the cellular areas were composed of cuboidal to polygonal cell nests or islands , irregularly distributed among abundant chondro - myxoid stroma [ figure 2 ] . the epithelial cells were also arranged in acinar and ductular pattern in some areas [ figure 2 ] . section show epithelial cell clusters in tubules , ducts , cords and nests and chondro - myxoid stroma with an area of cartilaginous tissue ( h and e , 100 ) excision site was healthy during the postoperative period and no recurrence was observed after 6 months of follow - up . nasse , first described a case of skin tumor containing both epithelial and mesenchymal components in 1892 . hirsch and helwig introduced the name chondroid syringoma and subsequently used as alternate to the term mixed tumor of skin . chondroid syringomas are defined as benign adnexal tumors containing both epithelial and mesenchymal elements with histological resemblance to benign mixed tumors of salivary glands . chondroid syringomas commonly present as nontender , firm , nodular , subcutaneous or intra - cutaneous masses of 0.5 - 3 cm diameter . previous literature have recorded a male predisposition and wide age range of 20 - 80 years . though most of the cases involve head and neck areas , cases involving trunk , extremities , axillary and scrotal areas the lesion was located at dorsal surface of left forearm , relatively a rare location . pailoor et al . reported a case of cytological diagnosis of chondroid syringoma involving little finger . chondroid syringomas are difficult to diagnose clinically because a wide range of nodular skin lesions simulate it such as , dermoid cyst , neurofibroma , dermatofibroma , pilomatrixoma , cutaneous histiocytoma and seborrheic keratosis . in the majority of the cases confirmatory diagnosis histologically chondroid syringomas can be categorized into two types - apocrine and eccrine , as classically described by headington . the apocrine types exhibit branching tubular pattern with cyst formation ( tubulo - cystic ) , lined by double cell layers ( cuboidal and flattened ) . whereas eccrine types show single layer of cuboidal epithelial cells surrounded by chondro - myxoid stroma . on immunohistochemistry , the inner cuboidal layer shows positive staining with epithelial markers like cytokeratin , whereas outer layer expresses mesenchymal markers such as vimentin , s-100 protein , neuron specific enolase and glial fibrillary acidic protein . though histopathology is a gold standard , fnac can suggest a diagnosis of chondroid syringoma on the basis of thick mucoid aspirates exhibiting distinct biphasic cell population of epithelial and myoepithelial cells in a fibrillary chondro - myxoid stroma . however sometimes , the aspirates may lack distinct biphasic cell populations or show predominantly monophasic cells , which create diagnostic difficulties . cytology is rarely applied for preoperative assessment of these nodular lesions . even in cases undergoing aspiration , smears are , usually , interpreted as benign adnexal tumors without proper categorization . previous literature have shown that accurate cytological diagnosis of chondroid syringoma is difficult . still fnac should be recommended to establish benign nature of the neoplasm and to differentiate from other common nodular skin lesions such as epidermal cyst , neurofibroma , cutaneous benign fibrous histiocytoma , etc . local excision with a cuff of normal tissue is desirable management in chondroid syringoma to avoid recurrence . malignant counterpart of chondroid syringoma is extremely rare , which may arise in a preexisting benign chondroid syringoma or may arise de novo . fine - needle aspiration cytology can be used as a useful preoperative diagnostic tool for diagnosis of cutaneous and sub - cutaneous lesions . diagnosis of chondroid syringoma can be possible by careful evaluation of a smear containing biphasic ( epithelial and myoepithelial ) cell population with chondro - myxoid fibrillary matrix in a mucoid aspirate obtained from a sub - cutaneous nodule . present case is a good example of cytological diagnosis of chondroid syringoma with histopathological correlation , which will encourage future workers to utilize this simple , cost effective diagnostic procedure for preoperative definitive diagnosis of this benign neoplasm helping clinicians to formulate proper management protocol with reduction of postsurgical recurrences .

chondroid syringoma is a rare benign adnexal tumor of sweat glands with microscopic resemblance to the salivary gland pleomorphic adenoma . cytology is rarely utilized for preoperative assessment of these slow - growing , small , nodular lesions . definitive cytological diagnosis is also quite difficult , and majority of the aspirates are evaluated as benign adnexal tumors leading to mandatory histopathological examination for pinpoint diagnosis . here , we report a case of chondroid syringoma of forearm , which was diagnosed by cytology and also confirmed after histopathological examination . pinpoint cytological diagnosis can help early formulation of necessary management protocol .

vlodya gribov devoted much of his life to studying the implications of unitarity for a high - energy s - matrix . my own work is based heavily on vlodya s ideas and formalisms and in this article , written in honor of what would have been his 75th birthday , i will outline results suggesting that high - energy unitarity could be a determining constraint on a particle s - matrix . i will first argue that a special version of qcd ( qcd@xmath2 ) , with experimentally attractive features , is selected as the strong interaction@xcite . a new color sextet quark sector is present that has just the right properties to produce electroweak symmetry breaking - with large cross - section effects predicted for the lhc . a unique embedding@xcite of the sextet sector in a left - handed @xmath0 theory ( gut@xmath2 ) removes the sextet electroweak anomaly and also , amazingly , includes `` almost exactly '' the lepton and triplet quark sectors of the standard model , with qcd@xmath2 included in it s entirety . because some of the @xmath3 quantum numbers are not quite right , gut@xmath2 can not be a conventional unified theory rather , it may provide an underlying _ massless _ field theory which dynamically generates , _ within the bound - state s - matrix , _ both the triplet and sextet hadronic sectors and , also , the leptonic sector of the standard model . if this proves to be the case then ( it will be arguable that ) unitarity uniquely determines the standard model ! my results imply that the infra - red chiral anomaly effects of a massless dirac sea can have a deep significance in a bound - state s - matrix . at high - energy , zero momentum chirality transitions ( within reggeon vertices ) produce states and amplitudes with dramatically different properties from those implied , at first sight , by the underlying field theory . in the s - matrix of massless qcd@xmath2 , _ the chirality transitions produce confinement and chiral symmetry breaking _ - with a minimal hadronic ( triplet and sextet ) spectrum@xcite , and critical pomeron high - energy behavior@xcite . although much remains to be understood about the s - matrix of gut@xmath2 , it is already clear that , _ just because of the dirac sea interactions , the standard model s - matrix could indeed emerge_. the @xmath0 symmetry is confined and so , very importantly , proton decay is not directly implied . in addition , because the chirality transitions occur only for vector coupled fermions , _ the real @xmath4 part of the theory dominates the s - matrix_. a resulting `` wee gluon anomaly interaction '' gives@xcite a mass for su(3 ) singlet left - handed vector bosons and the full interaction structure of the standard model appears . there is a related bound - state mass spectrum in which , because of the fermion representation structure , there are no ( unwanted ) symmetries . i will emphasize where gribov s work underlies the arguments that i present , beginning with the formulation of reggeon unitarity@xcite and ending with the importance of the dynamical role@xcite of the dirac sea . the critical pomeron solution@xcite of reggeon unitarity and the reggeization of non - abelian gauge theories ( that has been established , in remarkable depth , by lev lipatov and collaborators@xcite ) are also crucial . the multi - regge behavior of scattering amplitudes is determined by partial - wave amplitudes analytically continued in complex angular momentum . the singularity structure in each `` j - plane '' is controlled by @xmath5-channel unitarity . elastic unitarity generates regge poles which , in turn , generate regge cuts via multiparticle unitarity . the reggeon unitarity equations then determine the threshold discontinuity due to any combination of regge poles , in any partial - wave amplitude . if @xmath6 is a regge pole trajectory , the @xmath7-reggeon cut trajectory is @xmath8 . when the reggeon unitarity equations were first derived@xcite , they were a spectacular intellectual jump and a profound reformulation and generalization of existing low - order diagrammatic calculations . there were , however , many uncertainties in the derivation that were resolved only after the development@xcite of multiparticle symptotic dispersion relations as a fundamental basis for multi - regge theory . the generality of reggeon unitarity makes it extremely powerful , particularly when applied to the problem of constructing the multi - regge region qcd s - matrix . first we discuss the abstract reggeon field theory ( rft ) solution of these equations . the analogy with conventional unitarity makes it straightforward to formulate an effective field theory solution of reggeon unitarity . in fact , gribov developed@xcite a direct ( underlying ) diagrammatic formulation of rft only because@xcite of the uncertainties that , for a long time , surrounded the derivation of reggeon unitarity . we consider an , even - signature , pomeron regge pole with trajectory @xmath9 . if @xmath10 then , also , @xmath11 and all the multipomeron singularities accumulate at one point . in this case , a simultaneous solution of all the discontinuity formulae is essential and all rft diagrams have to be summed . remarkably , a renormalization group formalism can be applied and a fixed - point solution shown to exist . under a renormalization group transformation , which rescales both @xmath12 and @xmath13 , only the triple pomeron coupling @xmath14 survives as a relevant coupling . a fixed - point exists at @xmath15 and @xmath16 ( where @xmath17 and @xmath18 is the dimension of @xmath13 ) . @xmath19 gives an interacting pomeron theory with the `` universality '' property of a critical phenomenon . as a result , the asymptotic behavior can be precisely calculated without knowledge of the underlying `` bare '' parameters . scaling laws can be derived for a wide variety of cross - sections and it can be shown that all known @xmath20- channel unitarity constraints on a theory of rising cross - sections are satisfied@xcite . it can also be shown that , when @xmath5 is positive , all the multipomeron cuts separate and reggeon unitarity is satisfied . therefore , the critical pomeron provides a complete , unique , solution of high - energy unitarity which , in a sense , represents the ultimate achievement of the pre - qcd program to construct a unique s - matrix from unitarity . _ ( it has been my goal , for a long time , to determinine how and when the critical pomeron occurs in a field theory . ) _ the supercritical phase@xcite ( obtained when , formally , @xmath21 ) plays a crucial role in linking the critical pomeron to an underlying field theory . using a stationary point of the effective lagrangian introduces a `` pomeron condensate '' that generates new classes of rft diagrams . figure 1 contains a simple example of a new diagram . = 3.5 in reggeon unitarity determines that the @xmath13 poles produced by the two - pomeron propagators coupled to the condensate should be interpreted as particle poles lying on an odd - signature trajectory degenerate with that of the pomeron . the odd - signature reggeon couples pairwise to the pomeron and reggeon states involving many vector particle poles similarly appear in higher - order diagrams . in the supercritical phase , therefore , divergences in rapidity ( produced by @xmath22 ) are converted to vector particle divergences in @xmath13 that are associated with the `` deconfinement of a vector particle '' on the pomeron trajectory . if the critical pomeron is not present in a theory then , since perturbative cross - sections rise , it is unlikely that large momentum perturbation theory can match smoothly with unitary forward amplitudes . in fact , before even discussing dynamical details , we can give some general arguments that specifically link the critical pomeron to a special version of qcd ( qcd@xmath2 ) . breaking @xmath23 color to @xmath24 gives `` color superconducting qcd '' ( csqcd ) in which a massive , reggeized , vector particle ( a `` massive gluon '' ) is deconfined , just as is expected in the supercritical pomeron phase can be seen@xcite , without the detailed construction of the next section , by using cut rft to determine the center of the group . ] . however , at large momentum , a smooth transition from csqcd to qcd is possible only if an asymptotically free scalar `` higgs '' field can be employed . this is a strong requirement that is only possible@xcite if the asymptotic freedom constraint on qcd is `` saturated '' - immediately implying that there must be a further quark sector beyond that present in the conventional version of the standard model . also , in the infra - red transverse momentum region , the transition from csqcd to qcd can give the critical pomeron only if the infra - red divergences of perturbative reggeized gluon diagrams can generate non - perturbative pomeron diagrams describing a confining theory . as we will see , an infra - red fixed - point , that again exists only when asymptotic freedom is saturated , is crucial - in addition to chiral anomalies . the saturation constraint ( unrealistically ) requires sixteen color triplet quarks or , alternatively , two color sextets and six triplets ( giving qcd@xmath2 ) . the resulting `` sextet pions '' provide , exactly , a `` higgs sector '' producing electroweak mass generation@xcite . thus , requiring unitarity for the strong interaction leads directly to electroweak symmetry breaking and implies that there is a major sector of the strong interaction that has yet to be seen experimentally . the derivation of supercritical pomeron diagrams required@xcite the study of multi - regge amplitudes in which the `` pomeron condensate '' could be understood as due to a `` wee parton '' component of scattering hadrons . correspondingly , to derive supercritical states and amplitudes within csqcd@xmath2 , we have to consider a multi - regge limit@xcite in which the amplitude for the scattering of regge pole hadrons via pomeron exchange can emerge in it s entirety , as illustrated schematically in figure 2 . = 0.4in=2.4 in = 2.3 in fortunately , the generality of reggeon unitarity implies that the complicated reggeon diagrams involved can be constructed similarly to the well - known elastic scattering diagrams , the only difference being that vertices coupling distinct reggeon channels can contain anomalies not present in internal reggeon interactions . the main infra - red divergence of massless gluon reggeon diagrams is due to reggeization . this divergence exponentiates to zero all amplitudes with non - zero @xmath24 color in any reggeon channel . we consider diagrams , of the form shown in figure 3 , @xmath25=2.1 in = 2.4 in in which each reggeon state has two components , both of which carry zero @xmath24 color . one component contains massless gluons while the other is either a quark - antiquark pair or a massive gluon reggeon . we choose external left - handed vector boson vertices because , as illustrated in figure 4 , they directly = 4.8 in contain@xcite a triangle anomaly . consequently , an `` anomaly pole '' appears , as shown , when the gluon reggeons carry zero transverse momentum . the internal vertices in figure 3 contain u(1 ) anomaly diagrams of the form shown in figure 5 . the initial effect of the anomalies is a large transverse momentum ( non - unitary ) power enhancement@xcite of the high energy behavior . the enhancement can be removed with a transverse momentum cut - off but , because gauge invariance ward identities are violated , a new infra - red divergence is produced . an overall ( logarithmic ) divergence is generated when all massless gluon transverse momenta are scaled uniformly to zero . ( the @xmath26 anomaly pole contributes as a transverse momentum conserving @xmath27-function . ) however , when the massless gluon component in any reggeon state carries normal color parity ( @xmath28 signature ) , interactions with the second component in the state again exponentiate the divergence . for anomalous ( @xmath29 signature ) color parity gluon components , these interactions are absent . the infra - red fixed point , due to saturation , implies that color zero massless gluon reggeon interactions scale as all transverse momenta are scaled to zero . the overall `` anomalous wee gluon '' divergence is then preserved when interactions amongst the massless gluons are included . the residue of the divergence gives a physical csqcd@xmath2 amplitude , in which the transverse momentum cut - off can be removed and all the massless gluons in figure 3 contribute only as a `` reggeon condensate '' . the condensate provides ( crucial ) zero transverse momentum , anomalous wee gluon , components in both the `` pion '' and the `` pomeron '' . @xmath24 anomalous gluons must have odd signature and so the csqcd@xmath2 pomeron is an even signature regge pole which , because of the reggeon condensate , is exchange degenerate with a reggeized massive gluon , just as in supercritical rft . also because of the condensate , `` pion '' goldstone boson anomaly poles , from the external vertices , appear in the physical amplitudes . by removing the transverse momentum cut - off _ after the extraction of anomaly infra - red divergences _ , we replace ultra - violet chirality violation ( producing bad high - energy behavior ) by infra - red chirality violation producing particle poles . this is how a confining , chiral symmetry breaking , bound - state spectrum is generated out of reggeon diagrams . the spectrum consists of triplet and sextet quark / antiquark `` pions '' and , due to the equivalence of conjugate @xmath24 representations , tripet and sextet quark / quark ( and anti - quark / anti - quark ) `` nucleons '' . there is every indication@xcite that the reggeon diagrams of @xmath30 map onto supercritical rft , with the essential triple pomeron coupling given@xcite by wee gluon anomaly interactions . it remains , however , a major challenge to carry out the mapping in detail . assuming it can be done , the transition from csqcd@xmath2 to @xmath31 will necessarily give the critical pomeron . the reggeon condensate will disappear and the zero momentum chirality transitions ( which can , equivalently , be regarded as dirac sea shifts ) in states and amplitudes will no longer be due to a semi - classical gauge field with fixed @xmath23 color . the transitions will remain and will be many in any scattering process , but they will correspond to random , dynamical , gauge field fluctuations within the color group . the transition from a fixed `` magnetization '' for the dirac sea shifting gauge field , to a random , fluctuating , field characterizes the nature of the `` critical phenomenon '' that is associated with the high - energy behavior of @xmath31 . in effect , the longitudinal massive vector meson interactions do not decouple entirely as the color symmetry breaking is removed . they remain as dynamical fluctuations , but only at zero light - cone momentum . including such interactions ( specifically ) amounts to fixing the ( gribov ) ambiguity in the light - cone quantization of qcd@xmath2 . the quarks clearly have to be massless for the physics of qcd@xmath2 to be as we have described it . to add quark masses , and preserve the physics involved , appears non - trivial . the dirac sea would have to undergo major shifts , of the kind envisaged by gribov in his original confinement proposal@xcite , but in a random dynamical manner . in fact , the solution may be that effective quark masses are introduced via the bound - state masses originating from the embedding of @xmath31 in gut@xmath2 , that we discuss below . qcd@xmath2 baryons will be formed as bound states of csqcd@xmath2 nucleons and @xmath24 singlet quarks . crucially , because there are no chiral symmetries mixing the two sectors , there will be no `` hybrid '' sextet / anti - triplet / anti - triplet combinations . therefore , the only new baryons will be the sextet proton and the ( stable ) sextet neutron . sextet antiquarks have the same @xmath23 triality as triplet quarks and so we define `` standard model '' couplings for sextet antiquarks ( quarks ) to be the same as triplet quarks ( antiquarks ) . in an infinite momentum hadron , wee gluons should reproduce vacuum properties and , indeed , an anomaly interaction generates a mass for an exchanged vector boson , as illustrated in figure 6 . = 1.2 in = 3.8 in the sextet quark loop contribution is equivalent to the mixing of a sextet pion ( @xmath32 ) with a @xmath33 and gives @xmath34 where @xmath35 is a wee gluon momentum . the wee gluon origin implies this mass appears only in the s - matrix . it also occurs only for vectors with a left - handed coupling . no photon ( or gluon ) mass is generated ! both sextet and triplet pions contribute to the vector boson mass generation but , sextet pions dominate because of larger color factors . assuming the casimir scaling rule holds ( @xmath36 with @xmath37 ) , if @xmath38 evolves sufficiently slowly ( e.g. @xmath39 ) then @xmath40 can consistently be the electroweak scale ! the large wee gluon coupling to sextet quarks also implies that the wee gluon component of the pomeron couples very strongly ( @xmath41 ) to sextet quarks . this strong coupling is a central element of our understanding of high - energy sextet cross - sections . in general , the larger color factors involved imply that the sextet sector will be a higher mass , stronger coupling , part of the strong interaction . as a result sextet states and cross - sections will dominate at high enough energy . at first sight , the proposition that the sought - after new physics `` beyond the standard model '' is strong interaction physics seems very radical . however , it has a number of theoretical attractions and potentially answers a number of outstanding experimental problems , as the following list@xcite illustrates . -0.5=0.1 in 1 . electroweak symmetry breaking involves no new interaction besides the @xmath42 gauge interactions of the standard model . 2 . the electroweak scale is a new qcd ( sextet chiral ) scale , which casimir scaling shows to be the right order of magnitude . the spectrum is more limited than just color confinement and chiral symmetry breaking would imply , in better accord with experiment . glueballs and quark resonances are excluded as asymptotic states . there is no bfkl pomeron and no odderon . new large cross - section physics above the electroweak scale gives a natural explanation for many cosmic ray phenomena . big increases in average transverse momenta , and in the production of sextet neutrals , could give the apparent `` knee '' in the spectrum . 5 . the high - energy production of stable , neutral , sextet neutrons , in the early universe , provides a natural explanation for the dominance of dark matter - formed as nuclei , clumps , etc . from sextet neutrons . 6 . being neutral and massive , sextet neutrons will avoid the gzk cut - off and so could be the mysterious , ultra - high energy , cosmic rays . . top quark production could be due to the @xmath43 and sextet quark effects could explain an excess , large @xmath44 , jet cross - section at the tevatron . if the cosmic ray spectrum knee is associated with an effective threshold for sextet quark physics ( the energy is right , given that pomeron production is needed ) , large cross - section effects must appear very rapidly with energy to make the knee visible . such effects should be apparent at the lhc , with dramatic new physics involved@xcite . considering anomaly pole amplitudes , we can show that the strong coupling of the pomeron to sextet states implies that hard double pomeron production of electroweak vector bosons will give jet cross - sections comparable with normal qcd jet ( non - diffractive ) cross - sections . in particular , the boson pair cross - section is estimated to be , roughly , twelve orders of magnitude larger than in the standard model . combining this estimate with pomeron regge theory gives a small transverse momentum cross - section that is correspondingly large . during the initial `` soft physics '' running period , it should be straightforward@xcite to look for the vector boson pairs in the cms central detector that should be produced in combination with scattered protons in the totem roman pots . if pomeron exchange amplitudes are large , then cut - pomeron amplitudes should also be large . as a result , we expect very large inclusive cross - sections for sextet states ( multiple vector bosons , in particular ) across most of the rapidity axis . this implies that jet cross - sections , at very large transverse momentum , will be orders of magnitude larger than expected . the production cross - section for sextet nucleon pairs should also be hadronic in size , although stable sextet neutrons ( dark matter ! ) may be difficult to detect . if the sextet nucleon double pomeron cross - section is extraordinarily large , it might be detectable in the low luminosity run . if not , it might be seen by the high luminosity detectors@xcite that will look for double pomeron production of the standard model higgs particle . well above the electroweak scale , the @xmath31 infra - red fixed point requires @xmath45 , implying that the sextet sector can , naturally , produce the decrease in @xmath38 needed for unification . ( supersymmetry is not required ! ) a priori , unification could also determine how the @xmath3 sextet sector anomaly is canceled , as well as providing an origin for masses . many years ago ( with kyungsik kang ) we found@xcite a remarkable , but puzzling , result . we looked at asymptotically free , anomaly - free . left - handed unified theories that contain the sextet sector , we discovered that a unique theory is selected , i.e. @xmath0 gauge theory with the fermion representation @xmath46 ( @xmath47 gut@xmath2 ) . ( in any higher unitary group the sextet sector requires a representation that is too large for asymptotic freedom . ) under @xmath42 @xmath48 @xmath49 @xmath50 @xmath51 @xmath52 the triplet quark and lepton sectors , although not asked for , are remarkably close to the standard model . there are three `` generations '' of quarks / anti - quarks , with quark charges @xmath53 and @xmath54 , and three `` generations '' of @xmath24 doublet ( @xmath23 singlet ) leptons . the puzzle is that the @xmath3 quantum numbers are almost , but not quite , right and there are also ( apparently unwanted ) color octet quarks with lepton - like electroweak quantum numbers . at the time@xcite , we considered various `` anomalous fermion phenomena '' , but found no convincing dynamical route to the standard model . in fact , gut@xmath2 has similar properties to massless @xmath31 . asymptotic freedom is saturated and an infra - red fixed - point keeps the @xmath0 coupling very small . also , the @xmath0 symmetry can be broken to @xmath55 with an asymptotically free scalar field and so the high - energy s - matrix can be constructed via reggeon diagram anomaly interactions introduced by the symmetry breaking . because infra - red divergences will confine @xmath0 color in the s - matrix , _ all elementary fermions will be massless and confined_. the massless dirac sea will control the dynamics , but with a crucial difference from qcd@xmath2 . in gut@xmath2 , left - handed fermion interactions will exponentiate the anomalous color parity divergences that produce the states and amplitudes of qcd@xmath2 . therefore , these divergences _ will only be produced by the @xmath4 vector part of the theory . _ the left - handed vector bosons , with no su(3 ) color , will aquire a mass , as in section 8 . thus , just the interactions of the standard model will be selected within the gut@xmath2 s - matrix . as yet , very little is certain , but our current ideas@xcite about the s - matrix construction , and other properties of gut@xmath2 , can be listed as follows . ( we use @xmath56 . ) -1 * _ we begin with a @xmath13 cut - off and su(5 ) broken to su(2)@xmath57 . _ * _ the states are su(2)@xmath57 singlet goldstones ( @xmath58 s ) which are @xmath59 pairs in an su(2)@xmath57 condensate , as in csqcd@xmath2 . _ * _ the @xmath60 s contain @xmath61 s that are * 3 s , 6 s , * and * 8 s * under su(3)@xmath57 . ( * 8 s * are real wrt su(3)@xmath57 , but give complex doublets wrt su(2)@xmath57 . ) _ * _ anomaly interactions , involving the su(2)@xmath57 condensate , generate @xmath62 and @xmath63 masses via mixing ( predominantly ) with sextet @xmath60 s . _ * _ similar interactions should generate @xmath60 masses . the pattern , and how many parameters are involved , remains to be studied . _ * _ restoring su(2)@xmath64 symmetry gives su(2)@xmath57 _ x _ su(2)@xmath64 invariant states . _ * _ `` octet pions '' form bound state leptons with elementary `` leptons '' . _ * _ after su(2)@xmath64 confinement , the right - handed sextet flavor dependence gives a ( broken ) su(2 ) s - matrix symmetry . _ * _ with su(3)@xmath57 color , the pomeron is critical and the photon massless . _ * _ su(3 ) octet quarks have no chiral anomaly and hence no pomeron coupling - hence _ no strong interaction ! _ they appear in bound - state leptons as pairs of positive and negative energy massive states . _ * _ because the coupling is so small , the underlying su(5 ) theory will be close to conformal and the smallest lepton masses will be very small . _ * _ there are no spectrum symmetries that would prevent the s - matrix from having the full structure of the standard model . _ * _ the ( experimentally attractive ) su(5 ) value of the weinberg angle should be valid for gut@xmath2 , even though there is no proton decay ! _ * _ the * 144 * representation of so(10 ) is anomaly free , asymptotically free , and contains gut@xmath2 . there is , however , no `` saturation '' and so we can not construct a unitary , anomaly based , high - energy s - matrix . _ the success of the standard model is a major scientific achievement . nevertheless , it remains an enigma in the sense that there are a large number of parameters and there is no understanding of why it has been chosen by nature . the candidate theories / ideas that have so far been proposed for extending the model ( including supersymmetry and superstrings ) have failed to provide any understanding of the model s uniqueness and , as a result , have provided a wide range of possible extensions . in the search to understand the origin of the standard model , the importance of asking that physical states give a unitary s - matrix may been underestimated . when s - matrix theory reigned supreme@xcite , before the dramatic rebirth of field theory that has led to the standard model , awareness of the difficulty involved led to the proposal that there is a unique s - matrix that could , in principle , be bootstrapped from unitarity . in an asymptotically free field theory , the wild divergence ( non - summability ) of perturbative interactions occurs in the infra - red region . presumably , it is very difficult to keep this divergence out of the s - matrix . perhaps , there has to be a drastic reduction of the field theory degrees of freedom , in the states and in the interactions , that is only achievable ( in very special circumstances ) via infra - red anomalies of the massless dirac sea . could it be that the unitary s - matrix is indeed unique but that to construct it , knowledge of the ( also unique ) underlying _ massless field theory _ is essential ? v. s. fadin , e. a. kuraev and l. n. lipatov , _ sov . * 45 * , 199 ( 1977 ) ; v. s. fadin and l. n. lipatov , _ nucl . * b406 * , _ nucl . phys . _ * b477 * , 767 ( 1996 ) and further references therein ; j. bartels , v. s. fadin and r. fiore , _ nucl . * b672 * , 329 ( 2003 ) and references therein .

high - energy unitarity is argued to select a special version of qcd as the strong interaction . electroweak symmetry breaking has to be due to a new sextet quark sector - that will produce large cross - section effects at the lhc . the sextet sector embeds , uniquely , in a massless @xmath0 theory that potentially generates the states and interactions of the standard model within a bound - state s - matrix . infra - red chirality transitions of the massless dirac sea play an essential dynamical role . -0.4 in 8.5 in 1=0.5 in # 1 to # 1 # 1 # 1 to 2 # 1 # 1 to 1 in # 1 # 1#2#1#2 # 1#2#3 2 # 1#2 # 3 # 1#1| # 1| # 1 # 1#1 # 1#2#1| . # 2 # 1/ # 1| # 1| # 1#1 # 1 # 1#20=1=1>0.51-.500-.50-.5110>1 .50-.51 # 1#2 # 1#2 # 1 # 1\{. # 1 # 1=@xmath1= = # 1 # 1,by1 = 1 [ # 1]==,[#1]= # 1-#1- # 1(#1 ) # 1/#2 # 1@xmath1 # 1 # 1 # 1#2#3*#1 * , # 2 ( 19#3 ) # 1[#1 ] # 1 # 1 # 1 # 1(#1 ) * high - energy unitarity and the standard model * alan . r. white 0.6 cm argonne national laboratory 9700 south cass , il 60439 , usa . contributed to the proceedings of the gribov-75 memorial workshop .

periodontal regeneration is a multifactorial process and requires a multi - dependent sequence of biological events , including cell - adhesion , migration , proliferation , and differentiation . the ultimate goal of periodontal therapy is to regenerate the lost periodontal tissues caused by periodontitis . various controlled clinical trials have demonstrated that some of the available grafting procedures may result in periodontal regeneration in intrabony defects , but complete and predictable reconstruction of periodontal tissues is still difficult to obtain . the most positive outcome of periodontal regeneration procedures in intrabony defect has been achieved with a combination of bone graft and guided tissue regeneration . a complex series of events associated with periodontal regeneration involves recruitment of locally derived progenitor cells subsequently differentiated into the periodontal ligament ( pdl ) forming cells , cementoblasts or bone forming osteoblasts . therefore , the key to periodontal regeneration is to stimulate the progenitor cells to re occupy the defects . growth factors are the vital mediators during this process which can induce the migration , attachment , proliferation and differentiation of periodontal progenitor cells . platelet rich fibrin ( prf ) may be considered as a second generation platelet concentrate , using a simplified protocol , is a recently innovative growth factor delivery medium . carroll et al . 2005 , in vitro study demonstrated that the viable platelets released six growth factors like platelet - derived growth factor ( pdgf ) , vascular endothelial growth factor , transforming growth factor ( tgf ) , insulin - like growth factor , epidermal growth factor and basic fibroblast growth factor in about the same concentration for 7 days duration of their study . allows one to obtain fibrin mesh enriched with platelets and growth factors , from an anticoagulant free blood harvest without any artificial biochemical modification . the prf clot forms a strong natural fibrin matrix which concentrates almost all the platelets and growth factors of the blood harvest , and shows a complex architectures as a healing matrix , including mechanical properties that no other platelet concentrate can offer . it has been recently demonstrated to stimulate cell proliferation of the osteoblasts , gingival fibroblasts , and pdl cells but suppress oral epithelial cell growth . lekovic et al . in 2011 demonstrated that prf in combination with bovine porous bone mineral had ability to increase the regenerative effects in intrabony defects . in this report , we present the clinical and radiographic changes of a patient using prf along with xenograft as grafting material in the treatment of periodontal intrabony defect with endodontic involvement . the 25-year - old male was referred to department of periodontics , saveetha dental college , chennai , tamil nadu , india , with a complaint of periodontal abscess in relation to 11 . on examination , the patient was systemically healthy and had not taken any long - term antiinflammatory medications or antibiotics . on periodontal examination and radiographic evaluation , the patient presented with an intrabony defect extending up to apical third of right maxillary central incisor ( number 11 ) with a probing depth of 8 mm using william 's periodontal probe [ figures 1 and 2 ] . the patient did not present with pain in relation to number 11 tooth and had no pain on percussion . preoperative photograph preoperative radiograph initial therapy consisted of incision and drainage of the abscess , with antibiotic regimen for 5 days followed by oral hygiene instructions , which were repeated until the patient achieved an oleary et al . four weeks following phase 1 therapy , a periodontal re - evaluation was performed to confirm the suitability of number 11 tooth for this periodontal surgical procedure . clinical measurements were made using william 's periodontal probe with graduation to a precision of 1 mm . blood sample was taken on the day of the surgery according to the prf protocol with an remi 3000 centrifuge and collection kits . briefly , 6 ml blood sample was taken from the patient without an anti - coagulant in 10 ml glass test tubes and immediately centrifuged at 3000 rpm for 12 min . a fibrin clot was formed in the middle of the tube , whereas the upper part contained cellular plasma , and the bottom part contained red corpuscles . the prf clot was gently pressed between two sterile dry gauges to obtain a membrane which was later minced and added to the xenogenic graft material ( osseograf ) . an intrasulcular incision was made on labial and lingual aspect of the tooth of right anterior maxillary teeth ( number 11 , 12 , 13 ) along with two vertical incisions , extending to the muco gingival junction in relation to the distal aspect of number 13 and 11 . a full thickness trapezoidal flap was raised , and inner surface of the flap was curetted to remove the granulation tissue . root surfaces were thoroughly planed using hand instruments and ultrasonic scalers . the right maxillary central incisor demonstrated a circumferential intrabony defect is extending distally to affect right maxillary lateral incisor , after removing granulation tissue thoroughly , the intrabony defect was found to extend in buccal and apical aspect . briefly , minced prf was mixed with xenograft ( osseograf ) and was applied to the defect walls and root surfaces [ figure 3 ] . the flap were repositioned to their presurgical levels and sutured with silk utilizing an interrupted technique [ figure 4 ] . platelet rich fibrin plus bone graft condensed into the defect flap approximated and sutures placed after the operation , the patient was prescribed systemic antibiotics ( amoxicyllin 500 mg tid , 3 days ) , nonsteroidal antiinflammatory drug ( combiflam tid , 3 days ) and 0.12% chlorhexidine rinse ( twice a day for 4 weeks ) . the patient was seen at 1 week , 2 week , 1 month , 3 and 6 month [ figure 5 ] . postoperative photograph after 6 months follow - up periapical intraoral radiographs were obtained from the periodontal defect site at baseline and 6 months after surgery [ figure 6 ] . putty index was made , and patient was asked to bite on it along with that of the holder . postoperative radiograph after 6 months follow - up in this case report , the reduction in pocket depth and gain in clinical attachment were found after 6 months of follow - up [ table 1 ] . platelet rich fibrin by choukroun 's technique is prepared naturally without addition of thrombin , and it is hypothesized that prf has a natural fibrin framework and can protect growth factors from proteolysis . thus , growth factors can keep their activity for a relatively longer period and stimulate tissue regeneration effectively . the main characteristics of prf compared with other platelet concentrates , including prp , are that it does not require any anti - clotting agent . the naturally forming prf clot has a dense and complex three - dimensional architecture and this type of clot concentrates not only platelet , but also leukocytes . prf is simpler and less expensive to prepare , as well as being less risky to the patients . owing to its dense fibrin matrix , prf takes longer to be resorbed by the host , which results in slower and sustained release of platelet and leukocyte derived growth factors in to the wound area . in this case report , the decision to utilize minced prf as defect fillers in combination with xenograft was made because of its ease of manipulation and delivery to the surgical site . the intended role of the minced prf in the intrabony defect was to deliver the growth factors in the early phase of healing . despite of the fact that prf is a denser and firmer agent than other biological preparations , such as prp and enamel matrix derivative ( emd ) , it is still nonrigid to a degree that its space maintaining ability in periodontal defects is nonideal . it has been reported that the combination of a mineralized , rigid bone mineral , with a semi fluid , nonrigid agent , such as emd , significantly enhanced the clinical outcome of intrabony defects than treated without the addition of bone mineral . in another study , prf in combination in with bone mineral had ability in increasing the regenerative effects in intrabony defects . for that reason , we chose xenograft ( osseograf ) , hypothesizing that it could enhance the effect of prf by maintaining the space for tissue regeneration to occur . amorphous prf when used along with bio - oss for augmentation in maxillary atrophic cases showed reduced healing time and favorable bone regeneration . in this case report , the reduction in pocket depth and gain in clinical attachment were found after 6 months of follow - up . platelet rich fibrin could improve the periodontal osseous defect healing , as prf can up regulate phosphorylated extracellular signal regulated protein kinase expression and suppress the osteoclastogenesis by promoting secretion of osteoprotegerin ( opg ) in osteoblasts cultures . prf also demonstrates to stimulate osteogenic differentiation of human dental pulp cells by up regulating opg and alkaline phosphatase ( alp ) expression . furthermore , many growth factors are released from prf as pdgf , tgf and has slower and sustained release up to 7 days and up to 28 days , which means prf stimulates its environment for a significant time during remodeling . moreover , prf increase cell attachment , proliferation , and collagen related protein expression of human osteoblasts . prf also enhances protein kinase - like endoplasmic reticulum kinase , opg and alp expression , which benefits periodontal regeneration by influencing human pdl fibroblasts . according to the results obtained in this case report , the positive clinical impact of additional application of prf with xenogenic graft material in treatment of periodontal intrabony defect is based on : reduction in probing pocket depthgain in clinical attachment levelsignificant radiographic defect bone fillimproved patient comfort . reduction in probing pocket depth gain in clinical attachment level significant radiographic defect bone fill improved patient comfort . however , long - term , multicenter randomized , controlled clinical trial will be required to know its clinical and radiographic effect over bone regeneration .

for complete periodontal regeneration , delivery of growth factors in the local environment holds a great deal in adjunct to bone grafts . platelet rich fibrin ( prf ) is considered as second generation platelet concentrate , consisting of viable platelets , releasing various growth factors such as platelet - derived growth factor , vascular endothelial growth factor , transforming growth factor , insulin - like growth factor , epidermal growth factor and basic fibroblast growth factor . hence , this case report aims to investigate the clinical and radiological ( bone fill ) effectiveness of autologous prf along with the use of xenogenic bone mineral in the treatment of intra bony defects . intrabony defect was treated with autologous prf along with the use of xenogenic bone mineral . a decrease in probing pocket depth , gain in clinical attachment level and significant bone fill was observed at end of 6 months . the result obtained with the use of prf may be attributed to the sustained and simultaneous release of various growth factors over a period of 7 days . in this case report , the positive clinical impact of additional application of prf with xenogenic graft material in the treatment of periodontal intrabony defect was seen .

a variety of adhesive systems are continuously being developed in order to produce good adhesion to dental substrates . contemporary self - etching priming systems are one category of the simplified systems , which can demineralise and prime dentin simultaneously in one application . phase , which not only lessens clinical application time , but also significantly reduces technique - sensitivity or the risk of making errors during application and manipulation . another important advantage of the self - etch approach is that infiltration of resin occurs simultaneously with the self - etching process , by which the risk of discrepancy between both processes is low or non - existent.1 therefore self- etch adhesive systems have recently become popular in the clinic . there are many factors in clinical or laboratory conditions affecting the performance of adhesive systems . sometimes technique - sensitivity or material - related factors such as storage conditions to extend shelf life can also affect adhesive performance.2 manufacturers usually recommend to keep the adhesive systems in a refrigerator and to use as soon as possible within the expiration date . self - etching primer systems generally contain an acidic monomer ( mdp ) , hema and water . acidic monomers are hydrophobic , with an acidic radical such as a phosphoric or carboxyl radical at the end of their structure.3 for the acidity of the primer by the coexistence of the acidic monomer and water , hema is added to the primer solution . the acidic monomer demineralises the underlying dentin and penetrates into the demineralized collagen network . hema also promotes the permeation of monomers and bonding resin into demineralized collagen network , consistently to create a hybrid layer . se bond adhesive contains hema as a wetting agent , bis - gma and acidic monomer mdp.3 hema , described as essential to promotion of adhesion because of its excellent wetting characteristics.4 nakatsuka3 have been reported that both mdp and the tertiary amine are stable components , so the shelf life of se bond should be long and it s stable if refrigerated and even if at room temperature . the aim of this study was to evaluate the effect of storage temperature of se bond on bond strength to pulp chamber dentin . in this study , a self - etch primer bonding system clearfil se bond ( se bond , kuraray medical inc . , tokyo , japan and a resin restorative material clearfil photo posterior ( kuraray medical inc . , tokyo , japan ) were used . after removal of calculus and soft - tissue debris , the access cavities through the pulp chamber were opened . the pulp tissues were carefully removed and the crowns were separated at the cemento - enamel junction using a high - speed bur under water - cooling . the teeth were then randomly distributed into 4 groups and prepared as follows : clearfil se primer and se bond ( se bond , kuraray medical inc . , tokyo , japan ) were applied to the pulp chamber dentin according to the manufacturer s instructions , immediately after the delivery from the manufacturer and then the pulp chamber dentin was restored with a composite resin material ( clearfil photo posterior , kuraray co. , japan ) . the primer agent of the following groups was stored in a refrigerator and kept at 4c . the bonding system ( se bond ) used in this group was kept at 4c for 1 year in a refrigerator . after treatment with se primer , bonding agent was applied , cured for 20 s. and the pulp chamber was restored with the same resin composite material . the bonding system ( se bond ) used in this group was kept at 23c for 1 year at room temperature . after treatment with se primer , bonding agent was applied , cured for 20 s. and the pulp chamber was restored as in group 1 . the bonding system ( se bond ) used in this group after treatment with se primer , bonding agent was applied , cured for 20 s. and the pulp chamber was restored as in group 1 . the prepared specimens were kept in 37c water for 24 hrs before testing . after drying , the samples were fixed to a plexiglass block for testing procedures with sticky wax to permit creation of serial cross - sections 1 mm thick from the cej to apex using a isomet saw ( buehler ltd . , lake bluff , il ) . non - trimming method5 was used to obtain sample sticks with cross - sectional areas of 1 mm ( figure 1 ) and microtensile bond strengths to root canal dentin were measured . bond strength data was expressed in mpa and statistical analysis was performed using a one - way analysis of variance , followed by multiple comparisons were performed using a duncan test at 5% level of significance . in this study , a self - etch primer bonding system clearfil se bond ( se bond , kuraray medical inc . , tokyo , japan and a resin restorative material clearfil photo posterior ( kuraray medical inc . , tokyo , japan ) were used . after removal of calculus and soft - tissue debris , the access cavities through the pulp chamber were opened . the pulp tissues were carefully removed and the crowns were separated at the cemento - enamel junction using a high - speed bur under water - cooling . the teeth were then randomly distributed into 4 groups and prepared as follows : clearfil se primer and se bond ( se bond , kuraray medical inc . , tokyo , japan ) were applied to the pulp chamber dentin according to the manufacturer s instructions , immediately after the delivery from the manufacturer and then the pulp chamber dentin was restored with a composite resin material ( clearfil photo posterior , kuraray co. , japan ) . the primer agent of the following groups was stored in a refrigerator and kept at 4c . the bonding system ( se bond ) used in this group was kept at 4c for 1 year in a refrigerator . after treatment with se primer , bonding agent was applied , cured for 20 s. and the pulp chamber was restored with the same resin composite material . the bonding system ( se bond ) used in this group was kept at 23c for 1 year at room temperature . after treatment with se primer , bonding agent was applied , cured for 20 s. and the pulp chamber was restored as in group 1 . the bonding system ( se bond ) used in this group was kept in 40c incubator for 1 year . after treatment with se primer , bonding agent was applied , cured for 20 s. and the pulp chamber was restored as in group 1 . the prepared specimens were kept in 37c water for 24 hrs before testing . after drying , the samples were fixed to a plexiglass block for testing procedures with sticky wax to permit creation of serial cross - sections 1 mm thick from the cej to apex using a isomet saw ( buehler ltd . , non - trimming method5 was used to obtain sample sticks with cross - sectional areas of 1 mm ( figure 1 ) and microtensile bond strengths to root canal dentin were measured . bond strength data was expressed in mpa and statistical analysis was performed using a one - way analysis of variance , followed by multiple comparisons were performed using a duncan test at 5% level of significance . tokyo , japan ) were applied to the pulp chamber dentin according to the manufacturer s instructions , immediately after the delivery from the manufacturer and then the pulp chamber dentin was restored with a composite resin material ( clearfil photo posterior , kuraray co. , japan ) . the primer agent of the following groups was stored in a refrigerator and kept at 4c . the bonding system ( se bond ) used in this group was kept at 4c for 1 year in a refrigerator . after treatment with se primer , bonding agent was applied , cured for 20 s. and the pulp chamber was restored with the same resin composite material . the bonding system ( se bond ) used in this group was kept at 23c for 1 year at room temperature . after treatment with se primer , bonding agent was applied , cured for 20 s. and the pulp chamber was restored as in group 1 . the bonding system ( se bond ) used in this group was kept in 40c incubator for 1 year . after treatment with se primer , bonding agent was applied , cured for 20 s. and the pulp chamber was restored as in group 1 . the prepared specimens were kept in 37c water for 24 hrs before testing . after drying , the samples were fixed to a plexiglass block for testing procedures with sticky wax to permit creation of serial cross - sections 1 mm thick from the cej to apex using a isomet saw ( buehler ltd . , lake bluff , il ) . non - trimming method5 was used to obtain sample sticks with cross - sectional areas of 1 mm ( figure 1 ) and microtensile bond strengths to root canal dentin were measured . bond strength data was expressed in mpa and statistical analysis was performed using a one - way analysis of variance , followed by multiple comparisons were performed using a duncan test at 5% level of significance . the mean and standard deviation of microtensile bond strength values for the tested groups are shown in table 2 . statistically significant difference was found among group 4 and the other groups ( p<.05 ) . no significant difference was found among groups 1 , 2 and 3 ( p>.05 ) . keeping the adhesive system in incubator for 1 year reduced the bond strength of the adhesive system ( p<.05 ) . however keeping the adhesive system in refrigerator or room temperature did not effect bond strength when compared to the control group ( p>.05 ) . when the tested samples were evaluated under a stereomicroscope at x20 magnification , both tested groups showed mostly adhesive failure . investigations of environmental temperature and relative humidity during the restorative procedure are other relevant clinical aspects . several previous studies have reported the influence of temperature and relative humidity on early bond strengths of dentin.2,6 the presented study was investigated the effect of storage conditions on microtensile bond strength of a self - etching adhesive system . spohr et al7 investigated the tensile bond strengths of three adhesive systems ( scotchbond multi - purpose , single bond and prime&bond nt ) applied to dentin at refrigerated or room temperature and reported that no adverse effect was occurred when adhesive systems were used directly from refrigerated storage . in this study , confirming their results , keeping at 4c or 23c room temperature did not effect microtensile bond strength , on the other hand keeping at 40c incubator for one year significantly decreased bond strength ( p<.05 ) . hagge et al8 investigated the shear bond strength of adhesive systems applied at refrigerated and room temperatures and found no differences between prime & bond and all - bond 2 . on the other hand , shear bond strength of scotchbond multi - purpose was found to be higher at refrigerated temperature ( 13.14 mpa ) when compared to room temperature ( 5.52 mpa ) . they did not offer a satisfactory explanation for the improved bonding ability of refrigerated scotchbond multi - purpose . self - etch priming systems are generally contain an acidic monomer ( mdp ) , hema and water . it has been reported that hema is hydrolyzed to methacrylic acid and ethylene glycol in acidic conditions , and this hydrolysis is reported to be influenced by the storage temperature.9 as a matter of fact , results of in this study indicated that keeping the adhesive system in incubator for 1 year reduced the bond strength of the adhesive system ( p<.05 ) . however keeping the adhesive system in refrigerator or room temperature did not effect bond strength when compared to the control group ( p>.05 ) the chemical degradation of the adhesive resin due to the high temperature may occur and long term storage could affect bond strength to pulp chamber dentin . according to the results of this study se bond adhesive system should be kept in refrigerator until expiry date .

objectivesthe aim of this study was to evaluate the effect of storage temperature on bond strength of a self etching primer system to pulp chamber dentin.methodsse bond ( kuraray , japan ) adhesive system and clearfil photo posterior ( kuraray , japan ) composite resin were used . eight extracted caries - free human molar teeth were used . access cavities were prepared through the pulp chamber , randomly distributed into 4 groups and prepared as follows : group 1 ( control ) : se primer and se bond ( seb ) were applied to the pulp chamber dentin according to the manufacturer s instructions , immediately after the delivery from the manufacturer and then the pulp chamber was restored with a resin restorative material . the primer agent of the following groups was stored in a refrigerator and kept at 4c . group 2 : restored with seb , kept at 4c refrigerator for 1 year , group 3 : restored with seb kept at 23c room temperature for 1 year and group 4 : restored with seb kept at 40c incubator for 1 year . after 24 hrs the teeth were trimmed for microtensile bond testing and loaded to failure at 1mm / min . data were analyzed using one - way anova and duncan test ( p<.05).resultsthe results indicated that group 4 showed lowest bond strength when compared to the others ( p<.05 ) . no statistically significant difference was found among the other groups ( p>.05).conclusionsas a result of this study , it was concluded that increasing storing temperature or storing period decreases microtensile bond strength of a seb system to pulp chamber dentin .

Actor-director Kevin Smith is railing against air travel again, and this time he's joined by Khloe Kardashian and "Baywatch" babe Donna D'Errico. Smith, who was deemed too fat to fly by Southwest Airlines earlier this year, tweeted his ire about missing a Virgin Airlines flight Monday despite arriving at the gate with first-class tickets minutes before his scheduled departure. Meanwhile, Kardashian is drawing fire for comments she made Monday comparing the process of passing through airport security to being raped in public. "Well, they basically are just raping you in public," she told George Lopez on his TBS show. Kardashian said she opted for a pat down because she didn't want the "X-ray to see everything," but was shocked at how aggressive the screener was. "They say, 'OK, I'm going to be patting you down and I'm going to be touching the crease of your a--.' That is so inappropriate," she told Lopez, adding, "They are so aggressive and forceful." Kardashian said when she tried to lower her arms, the screener pushed them back up. "She said, 'Don't move or I'm going to get tough,'" she recalled. "I'm like, 'Going to get tough?' Geez." That's when Lopez interjected, "She might not have been TSA. She might have been a lady from the bar," drawing laughs. Former "Baywatch" star D'Errico was more reserved discussing her recent experience with airport screening but still questioned why she was singled out for what she called a "naked scan." "It is my personal belief that they pulled me aside because they thought I was attractive," D'Errico, who posed for the September 1995 issue of Playboy, told AOL News Monday. ||||| (Dec. 6) -- A former "Baywatch" beauty is feeling overexposed after going through what she says was a humiliating body scan by Transportation Security Administration agents at Los Angeles International Airport. Donna D'Errico, who was the Playboy Playmate in September 1995, says she got a few leers along with the scan and isn't happy about it. D'Errico, 42, says the encounter occurred at LAX while trying to catch a flight to Pittsburgh with her son, Rhyan, 17. "We were on our way to see Rhyan's aunt, who had just been put on life support in the ICU," D'Errico told AOL News in an exclusive interview. "My boyfriend and his business partner happened to be flying the same airline [American] on their way to New York for business. We got checked in and headed to security." After waiting in a long line of holiday travelers, D'Errico and her son finally made it to the moving carrier where all the carry-on bags are placed. That's when a TSA agent took her by the elbow and told her she needed to "come this way." Rebecca Sanabria "I said I was traveling with my son, motioning to him, and the agent said he was to come along with me as well," D'Errico said. "I immediately asked why we were having to go through an extra search, and no one else was being made to do so, indicating the long line of other passengers in front of and behind where we had been in line. In a very sarcastic tone, and still holding me by the elbow, the agent responded, 'Because you caught my eye, and they' -- pointing to the other passengers -- 'didn't.'"D'Errico is still wondering how she caught his eye while others didn't."My boyfriend and his partner sailed through with no problems, which is rather ironic in that my boyfriend fits the stereotypical 'look' of a terrorist when his beard has grown in a bit, which it was that evening," she said.Although D'Errico was a regular on "Baywatch" from 1996 to 1998, a period when it was one of the most popular shows worldwide, she doesn't know whether she was singled out because of her fame. Getty Images David McNew, AFP / Getty Images "I'm not sure whether they had recognized me or not," she admitted. "If they did, they didn't say anything. However, it is my personal belief that they pulled me aside because they thought I was attractive. My boyfriend, as I mentioned before, looks much more like a terrorist than either I or my son do, and he went through security with no problems."The TSA rules regarding scans and searches dictate that passengers can select a scan or a search. D'Errico says that was never an option."They never even told me what they were doing at all, or that I had any choice," she said. "It was just, 'Stand here. Raise your arms above your head like this.' They never told me that they were going to be conducting a full-body scan, or that I had the option of being searched instead. Had they explained what they were doing, I would have opted for the search. As a matter of fact, my son was made to not only go through the full-body scan, but they also conducted a pat-down search on him as well."After the search, I noticed that the male TSA agent who had pulled me out of line was smiling and whispering with two other TSA agents and glancing at me. I was outraged."So was her boyfriend, Roy J. Bank, the president of Merv Griffin Entertainment, who says he was in disbelief at what had just occurred."Anything that upsets Donna upsets me," he said. "I hated her being humiliated like that. I was genuinely shocked by both Donna and Rhyan being pulled aside for the extensive scanning."I'm all for measures to make us safer when traveling, but when it is so incredibly arbitrary, I don't feel any safer ... and I can promise you that her getting additional screening and the line full of people I saw around us not getting additional screening is not making us any safer!"Although some might wonder why a woman who appeared nude in Playboy and wore a red bathing suit for three seasons of "Baywatch" is bothered about having one or two TSA agents see a computer scanned image of her naked body, but D'Errico says they are two separate issues."I must have overlooked the clause in both my Playboy and 'Baywatch' contracts stating that once appearing in that magazine, or on that show, I would forever be subject to being seen naked live and in person by anyone, at anytime, under any conditions, whether I agree to it or not, and for free," she said sarcastically."I posed for Playboy 15 years ago. I was on 'Baywatch' 13 years ago. Both of those were controlled environments, with proper lighting, makeup, etc., and were jobs. I contractually agreed to do both of those jobs. I could have stopped or changed my mind at any time. None of those conditions are present when TSA decides for you that you will consent to being scanned or felt up, or you simply won't be allowed your constitutional right to travel from one place to another freely."TSA spokesman Nico Melendez thinks D'Errico's claims aren't accurate."If you see the images, you'll know it's not a naked picture," he said. "The passengers are selected at random and not because they're celebrities."As far as her claims that the agents were smiling and whispering, Melendez said that people who are celebrities shouldn't be surprised if and when they're recognized.But D'Errico says that even though she has a higher profile than other people, she fears other women may be victims of this invasion of privacy."This could, and I'm sure does, happen to other women," she said. "It isn't right to hide behind the veil of security and safety in order to take advantage of women, or even men for that matter, so that you can see them naked. It's a misuse of power and authority, and as much a personal violation as a Peeping Tom. The difference is that Peeping Toms can have charges pressed against them."Melendez says that the agents who are looking at the scan are in a closed room and have no communication with anyone other than the person handling the machine."It could be a woman or a man," he said.D'Errico doesn't know of any other actresses or models who've had the same experience, but she believes other more effective and less invasive security measures should be implemented."One of my best friends was flying to New York for business, and at some point during the flight, she stood up to retrieve something from her bag in the overhead compartment," she said. "When she reached into her bag, something cut her hand. She looked into her bag and discovered a pair of 6-inch gardening shears which she had forgotten to remove prior to packing her bag."The bag, and my friend, had passed through security with no issues. How is this full-body scan supposed to be making us safer if 6-inch gardening shears can still make it aboard domestic flights undetected?"

– A furious Khloe Kardashian has compared the humiliating exposure of show-all airport scanners with being "raped in public." But that was before she opted instead for a pat down that turned out to be shockingly "aggressive," notes ABC News. They say," 'OK, I'm going to be patting you down and I'm going to be touching the crease of your ass.' That is so inappropriate," she said on George Lopez Tonight ... "Did they, Khloe? Did they really say 'ass'?" asks Gawker's Richard Lawson, who goes on to slam Kardashian for comparing her experience to rape, accusing the "low-rent, third-best sister" of an outrageous attention ploy. "She's not the only bargain basement celebrity to seek some sort of currency from the whole TSA body scanning thing," he continues: Former Baywatch star Donna D'Errico also complained about the new invasive screening procedures. She's convinced she was subjected to a full body scan because agents wanted to check her out. She said the agent told her: "You caught my eye," and that he was smiling and whispering with other guards as they peered at her after her scan. Click for more on the Baywatch babe's experience.

we have systematically constructed a low - energy effective field theory for hole- and electron - doped antiferromagnets @xcite . the construction relies on basic principles of quantum field theory as well as on a symmetry analysis of the hubbard or @xmath5-@xmath6 model . as an experimental input we take angle resolved photoemission spectroscopy ( arpes ) measurements which provide us with the fact that doped holes reside in momentum space pockets centered at @xmath7 and that electrons live in pockets centered at @xmath1 or @xmath2 . a key ingredient of the effective theory is the nonlinear realization of the spontaneously broken global @xmath8 symmetry . using this nonlinearly realized symmetry , the magnons are coupled to the electrons or holes via two vector fields . for reasons of space limitations , here we are not going to show the terms in the effective action . the reader will find all terms properly constructed and listed in @xcite for hole doping and in @xcite for electron doping . using the systematic and powerful framework of the low - energy effective theory , we first investigate the magnon - mediated binding of a pair of holes or a pair of electrons in an otherwise undoped antiferromagnet . solving the corresponding schrdinger equation , we find bound state wave functions that resemble @xmath9-wave - like symmetry . in a second step we study possible ground states of lightly doped antiferromagnets . in the hole - doped case either a homogeneous phase or a spiral phase is energetically favored . in the electron - doped case the effective theory predicts the absence of a spiral phase . let us now focus on the one - magnon exchange between two holes originating from two different pockets , i.e. one hole from @xmath10 and the other hole from @xmath11 . the two holes have antiparallel spin , i.e. spin @xmath12 and @xmath13 , otherwise no magnon could be exchanged . evaluating the feynman diagram for one - magnon exchange and integrating out the magnons , the long - range behavior of the resulting potential is given by @xmath14 where @xmath15 is the distance vector between the two holes and @xmath16 is the angle between @xmath17 and the @xmath18-axis , while @xmath19 determines the strength of the hole - one - magnon coupling . note that the one - magnon - exchange flips the spin of the holes , such that also @xmath17 is flipped , i.e. @xmath20 . we now investigate the corresponding two - component schrdinger equation for the relative motion of the two holes . the two components are the probability amplitudes for the flavor - spin combinations @xmath21 and @xmath22 . due to the @xmath23-dependence of the potential , the schrdinger equation separates into an angular- and a radial equation , which both have analytical solutions . we find that the ground state is two - fold degenerate . combining the two ground state wave functions for the two - hole bound state to an eigenstate of 90 degrees rotation leads to the probability distribution shown in fig . 1 resembling @xmath3-like symmetry . , scaledwidth=43.0% ] the effective theory is also a very powerful tool to investigate the regime of small doping . in this regime we study possible ground states of the hole - doped system @xcite . we allow candidate configurations of the staggered magnetization that lead to homogeneous fermion densities . we have proven that this is possible only if the staggered magnetization is constant itself or if it describes a time - independent spiral . in the pure magnon sector , due to the spin stiffness @xmath24 , a spiral costs more energy than the homogeneous configuration . however , due to the hole - one - magnon vertex in the effective action @xcite , some of the fermions can gain energy in the spiral background , which provides a mechanism for stabilizing a spiral . based on analytical calculations , in @xcite , we work out how the hole pockets are populated and whether a homogeneous or a spiral phase in the staggered magnetization is realized depending on the low - energy parameters @xmath24 , @xmath19 and the hole mass . we find that for large @xmath25 a homogeneous phase is realized , while for intermediate values of @xmath25 a spiral along a lattice axis is realized . both configurations of the staggered magnetization are shown in fig . 2 . for small values of @xmath25 a yet unidentified inhomogeneous phase is energetically favored . using the effective theory , we also calculate the one - magnon exchange potential between two electrons with antiparallel spins . introducing the total momentum @xmath26 of the electron pair , the potential is given by @xmath27.\ ] ] here @xmath28 is the angle between the total momentum @xmath26 and the @xmath18-axis , while @xmath29 is the distance vector between the two electrons and @xmath16 is the angle between @xmath17 and the @xmath18-axis . the strength of the electron - one - magnon coupling is determined by @xmath30 . note that for @xmath31 , the potential between two electrons is proportional to @xmath32 , while between two holes it is proportional to @xmath23 . as a result , for large distances , one - magnon exchange is stronger between two holes than it is between two electrons . numerically solving the schrdinger equation for a pair of electrons interacting via one - magnon exchange we find the probability distribution of the groundstate , which is shown in fig . 1 for @xmath33 . note that this probability distribution resembles @xmath4-symmetry . also in the electron - doped antiferromagnet the effective theory provides a reliable tool to study a lightly doped system . we examine spirals in the staggered magnetization as a possible ground state @xcite . the analysis works similar to the one in the hole - doped case discussed before . however , as a consequence of the weakness of the one - magnon - electron coupling , we find that the electron - doped systems do not favor a spiral in the staggered magnetization . we have systematically constructed a low - energy effective theory for magnons and charge carriers in an antiferromagnet . using the effective theory many interesting aspects of low - energy physics in antiferromagnetic systems can be addressed in a very systematic and transparent manner .

we have constructed a systematic low - energy effective theory for hole- and electron - doped antiferromagnets , where holes reside in momentum space pockets centered at @xmath0 and where electrons live in pockets centered at @xmath1 or @xmath2 . the effective theory is used to investigate the magnon - mediated binding between two holes or two electrons in an otherwise undoped system . we derive the one - magnon exchange potential from the effective theory and then solve the corresponding two - quasiparticle schrdinger equation . as a result , we find bound state wave functions that resemble @xmath3-like or @xmath4-like symmetry . we also study possible ground states of lightly doped antiferromagnets . , , , , , effective field theory ; antiferromagnets ; magnons ; spirals 74.20.mn,75.30.ds,75.50.ee,12.39.fe

in this paper we obtain time - uniform estimates for the convergence of a class of interacting diffusion stochastic differential equations towards the associated mean field equation . the propagation of chaos resulting from this convergence when the number of particles @xmath1 tends to infinity is uniform in time which means that not only the particles are independent of each other , but also this independence is reached uniformly in time . the @xmath1-particle interacting diffusion model is of the following form @xmath2 here @xmath3 are independent wiener processes , @xmath4 is a constant and @xmath5 , @xmath6 , are measurable functions . we will explain further below our reasons for studying this type of model . for a probability measure on @xmath7 , @xmath8 , write @xmath9 . the limiting processes @xmath10 are defined to be @xmath11 where @xmath12 is the law of @xmath13 . the classical propagation of chaos result states that , under suitable conditions on @xmath14 and @xmath15 , the probability law of @xmath16 over some fixed time interval @xmath17 $ ] ( this being a probability law on @xmath18;{{\mathbb r}})$ ] ) , converges weakly to the probability law of @xmath19 . refer to @xcite for more details . we briefly consider the following toy model to motivate our problem . consider for the moment the system @xmath20 where @xmath21 has lipschitz constant @xmath22 . define @xmath23 where @xmath24 is the law of @xmath25 . assume that both of the above equations have strong solutions . using gronwall s inequality and the cauchy - schwartz inequality , @xcite obtained a bound of the form @xmath26}|y^j_t - \bar{y}^j_t|\right ] \leq\exp\left ( 2 t \tilde{b}^{lip}_n\right)\sup_{s\in [ 0,t]}{\mathbb e}\left[b_1(\bar{y}^j_s,\bar{y}^k_s)^2\right]^{\frac{1}{2}}.\ ] ] it is clear from the above that @xmath27 is a good approximation to @xmath28 when @xmath29 . it is also clear that as @xmath30 , this bound becomes very poor , particularly due to the exponentiation . in much modeling of interacting diffusions , such as neuroscience , it is difficult to assume that @xmath31 is small : indeed , often it is difficult to properly model the ` start ' of a system . it is therefore desirable to obtain convergence results which are uniform in time . this is the focus of this paper . for @xmath32 , let @xmath33 for some functions @xmath34 and @xmath35 described further below . we expect ( but do not require ) @xmath36 to be of the form @xmath37 where @xmath38 is a positive integer . @xmath36 modulates the rate of convergence for when @xmath16 is ` close ' to @xmath19 . @xmath35 is a weight function which modulates the behavior for when @xmath39 or @xmath40 asymptote to @xmath41 . if @xmath0 is a metric , then this result guarantees that the wasserstein distance ( with respect to @xmath0 ) between the laws of @xmath16 and @xmath19 converges to zero as @xmath42 , with a rate which is uniform in @xmath43 . as a consequence of theorem [ theorem major result ] , and since @xmath0 is a metric , the result guarantees that the joint law of any finite set of neurons(or particles in the general case ) converges to a tensor product of iid processes , each with law given by the sde in ( [ eqn limit system ] ) . it is easily verified as explained in corollary [ corollary1 ] . to the best of our knowledge , the first work on uniform propagation of chaos was @xcite when approximating feynman kac formula for non linear filtering . other authors applied log - sobolev inequalities and concentration inequalities @xcite . most of the previously cited works assume that the interaction term is of the form @xmath44 and the local term is of the form @xmath45 for some @xmath46 satisfying certain convexity properties . this work is essentially a generalization of @xcite . we are motivated in particular by the application of these models to neuroscience ( see for instance @xcite ) although we expect in fact that these results are applicable in other domains such as agent - based modeling in finance , insect - swarms , granular models and various other applications of statistical physics . we have been able to weaken some of the requirements in @xcite and other works , so that the results may be applied in arguably more biologically realistic contexts . we do not assume that the interaction term @xmath47 is a function of @xmath48 , as in many of the previously cited works . the uniform propagation of chaos result is essentially due to the stabilizing effect of the internal dynamics ( @xmath49 term ) outweighing the destabilizing effect of the inputs from other neurons ( @xmath21 term ) and the noise ( @xmath15 term ) . in @xcite , it was assumed that the gradient of @xmath49 is always negative , and is at least linear . however it is not clear ( at least in the context of neuroscience ) that the decay resulting from the internal dynamics term is always this strong for large values of @xmath39 . neuroscientific models are only experimentally validated over a finite parameter range , and therefore it is not certain how to model the dynamics for when the state variable @xmath16 is very large or small . our more abstract setup does not require the decay to be linear ( as in for example the wilson - cowan model ) for large values of @xmath39 : indeed the decay could be sub - linear or super - linear ; all that is required is that in the asymptotic limit the decay from @xmath49 dominates the destabilizing effects of @xmath21 and @xmath15 . another improvement of our model over @xcite is that we consider multiplicative noise ( i.e. @xmath50 ) . this is more realistic because we expect the noise term @xmath51 to be of decreasing influence as @xmath39 gets large . this is because one would expect in general that the system is less responsive to the noise when its activity is greatly elevated , since the system should be stable . the point is that experimentalists should have some liberty in fitting our model to experimental data ; all that is required is that in the asymptotic limit the decay from @xmath49 dominates the destabilizing effects of @xmath21 and @xmath15 . we do not delve into the details of existence and uniqueness of solutions , and so throughout we assume that [ assumption one ] there exist unique strong solutions to and . our major result is the following uniform convergence property . [ theorem major result ] if assumption [ assumption one ] and the assumptions in section [ sect assumptions ] hold , then there exists a constant @xmath52 such that for all @xmath53 @xmath54 \leq k n^{-\frac{a}{q(a-1)}},\ ] ] for integers @xmath55 and @xmath56 . it is easy to show existence and uniqueness if , for example , @xmath14 and @xmath15 are each globally lipschitz . in the case of existence and uniqueness of , * theorem 3.6 ) provides a useful general criterion . refer to @xcite for a discussion of how to treat the existence and uniqueness of in a more general case . our paper is structured as follows . in section [ sect assumptions ] we outline the assumptions of our model , in section [ section proof ] we prove theorem [ theorem major result ] and in section [ application ] we outline an example of a system satisfying the assumptions of section [ sect assumptions ] . the requirements outlined below might seem quite tedious . however in the next section we consider an application which allows us to simplify many of them . we split @xmath7 into two domains @xmath57 and @xmath58 . @xmath59 is a closed compact interval which we expect the system to be most of the time . over @xmath57 , we require that the natural convexity of @xmath49 dominates that of @xmath21 and @xmath15 . in @xmath58 we require bounds for when the absolute values of the variables are asymptotically large . assume that @xmath60 , that @xmath61 , @xmath35 and @xmath62 if and only if @xmath63 . suppose that for @xmath64 , @xmath65 and clearly @xmath66 . write @xmath67 . assume that for all @xmath32 , @xmath68 assume that for all @xmath69 , there exists a constant @xmath70 such that @xmath71 assume that for all @xmath72 , there is some @xmath55 such that @xmath73 assume that there exists a constant @xmath74 such that for all @xmath75 , @xmath76 assume that for @xmath75 , for all probability measures @xmath8 and all @xmath77 , @xmath78 @xmath79 assume that there exist constants @xmath80 such that for all @xmath81 , @xmath82 assumption might seems a little strange . if @xmath83 as @xmath84 , in the context of neuroscience it would mean that the relative influence of neuron @xmath38 on neuron @xmath85 decreases as @xmath86 . this seems biologically reasonable . we assume that @xmath87 dominates the other terms , i.e. @xmath88 for some positive integer @xmath89 , we require that there exists a constant @xmath90 such that for all @xmath91 , @xmath92 \leq c_2.\label{eq b1 q bound}\end{aligned}\ ] ] assume that there exists a constant @xmath93 such that for all @xmath94 and for all @xmath1 , @xmath95,{\mathbb e}\left [ g(x_s)^{\frac{2(a-1)q}{aq - a - q}}\right ] \leq c_1.\label{eq g bound}\ ] ] we now outline the proof of theorem [ theorem major result ] . we will prove that there exists a constant @xmath96 such that @xmath97 \leq \int_0^t -c { \mathbb e}\left [ h(x^j_s,\bar{x}^j_s)\right ] + cn^{-\frac{1}{q}}{\mathbb e}\left [ h(x^j_s,\bar{x}^j_s)\right]^{\frac{1}{a}}ds.\ ] ] the theorem will then follow from the application of lemma [ lemma ut ] to the above result . we observe using ito s lemma that @xmath98 the @xmath99 are @xmath100 we start by establishing that @xmath101 \leq -c_0 \int_0^t { \mathbb e}\left [ h(x^j_s,\bar{x}^j_s)\right]ds.\ ] ] we prove that the sum of the integrands of @xmath102,@xmath103,@xmath104 and @xmath105 is less than or equal to @xmath106 . suppose firstly that @xmath107 . then the integrands of @xmath108 and @xmath105 are all zero . furthermore , using , the integrand of @xmath102 satisfies the bound @xmath109 now suppose that @xmath110 . the integrand of @xmath102 is less than or equal to zero because of . through , @xmath111 \geq g(\bar{x}^j_s)c_0 f(\bar{x}^j_s - x^j_s).\end{gathered}\ ] ] since @xmath112 and @xmath113 , upon multiplying the above identity by @xmath114 , @xmath115 + \frac{1}{2 } f(x^j_s - \bar{x}^j_s)g'(x^j_s)g'(\bar{x}^j_s)b_2(x^j_s)b_2(\bar{x}^j_s)\\ \leq -c_0 h(x^j_s,\bar{x}^j_s)-\frac{1}{2}a_0g(x^j_s)g'(\bar{x}^j_s)b_2(\bar{x}^j_s ) f(x^j_s - \bar{x}^j_s)+\\ \frac{1}{2 } f(x^j_s - \bar{x}^j_s)g'(x^j_s)g'(\bar{x}^j_s)b_2(x^j_s)b_2(\bar{x}^j_s ) \leq - c_0 h(x^j_s,\bar{x}^j_s),\label{int temp 3}\end{gathered}\ ] ] since by , @xmath116 notice that the left hand side of is the sum of the integrand of @xmath103 and half of the integrand of @xmath105 . similarly if @xmath117 , the integrand of @xmath102 is less than or equal to zero , and through and , @xmath118 + \frac{1}{2 } f(x^j_s - \bar{x}^j_s)g'(x^j_s)g'(\bar{x}^j_s)b_2(x^j_s)b_2(\bar{x}^j_s)\\ \leq -c_0 h(x^j_s,\bar{x}^j_s)-\frac{1}{2}a_0g'(x^j_s)g(\bar{x}^j_s)b_2(x^j_s ) f(x^j_s - \bar{x}^j_s)+\\ \frac{1}{2 } f(x^j_s - \bar{x}^j_s)g'(x^j_s)g'(\bar{x}^j_s)b_2(x^j_s)b_2(\bar{x}^j_s ) \leq - c_0 h(x^j_s,\bar{x}^j_s).\label{int temp 4}\end{gathered}\ ] ] the left hand side of the above is equal to the integrand of @xmath104 and half of the integrand of @xmath105 . observe that if @xmath119 , then the left hand side of is zero because @xmath120 is zero in @xmath57 . similarly if @xmath121 , then the left hand side of is zero because @xmath120 is zero in @xmath57 . these considerations yield the bound . it follows from that @xmath122 \leq c_2 \int_0^t { \mathbb e}\left [ h(x^j_s,\bar{x}^j_s)\right]ds.\ ] ] we finish by bounding the @xmath123 term . suppose that @xmath124 . then using , - and the triangular inequality @xmath125 we obtain the same inequality when @xmath126 . that is , @xmath127 applying holder s inequality to the above , @xmath128 \leq\\ \grave{c}_1 { \mathbb e}\left[g(x^j_s)g(\bar{x}^j_s)f(x^j_s - \bar{x}^j_s)\right ] + \\ \breve{c}_1 { \mathbb e}\left[g(x^j_s)g(\bar{x}^j_s)f(x^j_s-\bar{x}^j_s)\right]^{\frac{1}{a}}{\mathbb e}\left[g(x^k_s)g(\bar{x}^k_s)f(x^k_s - \bar{x}^k_s)\right]^{\frac{a-1}{a } } \\ = ( \grave{c}_1 + \breve{c}_1){\mathbb e}\left[g(x^j_s)g(\bar{x}^j_s)f(x^j_s - \bar{x}^j_s)\right ] \end{gathered}\ ] ] we use holder s inequality to see that @xmath129 \leq \\ { \mathbb e}\left [ f'(x^j_s - \bar{x}^j_s)^a g(x^j_s)g(\bar{x}^j_s)\right]^{\frac{1}{a } } { \mathbb e}\left [ g(\bar{x}_s^j)^{\frac{a-1}{a}\times\frac{2aq}{aq - a - q}}\right]^{\frac{aq - a - q}{2aq}}\times\\ { \mathbb e}\left [ g(x_s^j)^{\frac{a-1}{a}\times\frac{2aq}{aq - a - q}}\right]^{\frac{aq - a - q}{2aq}}\times { \mathbb e}\left[\left(\sum_{k=1}^n b_1(\bar{x}^j_s,\bar{x}^k_s ) - \bar{b}_1(\bar{x}^j_s,\bar{\mu}_s)\right)^q\right]^{\frac{1}{q}}.\end{gathered}\ ] ] where @xmath130 is the integer that appears in assumption . + by assumption , @xmath131^{\frac{aq - a - q}{aq}}\times { \mathbb e}\left [ g(x_s^j)^{\frac{2(a-1)q}{aq - a - q}}\right]^{\frac{aq - a - q}{aq}}\ ] ] is uniformly bounded for all @xmath132 . furthermore through assumption and lemma [ lemma bound polynomial ] , @xmath133^{\frac{1}{q}}$ ] is bounded by @xmath134 . finally , using assumption , @xmath135^{\frac{1}{a } } \leq { \mathbb e}\left[h(x^j_s,\bar{x}^j_s ) \right]^{\frac{1}{a}}.\ ] ] we thus find that for some constant @xmath96 , @xmath136 \leq c\int_0^t n^{-\frac{1}{q}}{\mathbb e}\left[h(x^j_s,\bar{x}^j_s)\right]^{\frac{1}{a}}ds.\ ] ] in summary , noting the assumption , we now have all the ingredients for . [ corollary1 ] let @xmath137 and fix @xmath138 neurons @xmath139 . under the assumptions of theorem 1 , the law of @xmath140 , converges toward @xmath141 for all @xmath53 . @xmath142 \leq \sum^{l}_{k=1 } { \mathbb e}\left [ \left|x^{i_{k}}_{t}-\bar{x}^{i_{k}}_{t}\right|^2\right ] \leq l k n^{-\frac{a}{q(a-1)}},\ ] ] hence @xmath143 the law of @xmath144 converges when @xmath1 tends to infinity to the law of @xmath145 , whose law is equal to @xmath141 by definition . we present now the lemmas used in the proof of theorem [ theorem major result ] . [ lemma bound polynomial ] suppose that @xmath146 are independent identically - distributed @xmath7-valued random variables such that @xmath147 < \infty$ ] and @xmath148 = 0 $ ] . then there exists a constant @xmath149 such that for all @xmath1 @xmath150 < \mathfrak{c } n^{q-1}.\ ] ] consider the binomial expansion of @xmath151 . there are @xmath152 terms in total . the expectation of at least @xmath153 of these must be zero , as the constituent factors are all independent . let @xmath154 , @xmath155 , be an arbitrary set of indices . then through holder s inequality , @xmath156 \leq { \mathbb e}\left [ ( e^1)^q\right].\ ] ] thus @xmath157 \leq\\ { \mathbb e}\left [ ( e^1)^q\right]\times\left ( n^q - n\times ( n-1)\times ( n-2)\times \ldots ( n - q+1)\right ) \\ \leq { \mathbb e}\left [ ( e^1)^q\right]\times \left ( n^q - ( n - q+1)^q\right)\\ = { \mathbb e}\left [ ( e^1)^q\right]n^{q-1}\left ( n - n\left ( 1 - \frac{q-1}{n}\right)^{q-1}\right ) \leq { \mathbb e}\left [ ( e^1)^q\right]n^{q-1}(q-1)(q-2).\end{gathered}\ ] ] the following lemma is an easy generalization of a result in @xcite . [ lemma ut ] suppose that @xmath158 is continuous and satisfies , for some constants @xmath159 and positive integer @xmath160 , for all @xmath161 , @xmath162 furthermore @xmath163 . then for all @xmath53 @xmath164 it may be seen that @xmath158 is differentiable , with the derivative satisfying @xmath165 let @xmath166 . then @xmath167 if @xmath168 then there is nothing to show . thus we may assume that for all @xmath169 , @xmath170 . hence @xmath171 upon integration , @xmath172 thus @xmath173 in this section we are going to provide an example of a system satisfying the requirements of section [ sect assumptions ] , so that the result of theorem [ theorem major result ] will apply . we start by defining the following functions . + for all @xmath174 , let @xmath175 let @xmath176 $ ] for some @xmath177.we take @xmath178 and @xmath179 . define the sigmoid function @xmath180 , it is clear that @xmath181 is of class @xmath182 , @xmath183 and its derivative is bounded and positive . using this , we define @xmath184 we consider a population of @xmath1 neurons , with evolution equation @xmath189 where @xmath190 is the membrane potential of neuron @xmath85 , @xmath191 is the deterministic input current . @xmath192 denotes the synaptic weight from neuron @xmath38 to neuron @xmath85 . the function @xmath193 is assumed to be of class @xmath194 in both variables , such that both it and its derivative are bounded . + the above assumptions are sufficient for the requirements of section [ sect assumptions ] to be satisfied . in particular , using the mean value theorem , one can easily verify the bounds [ eq c1 bound 1 ] and [ eq c1 bound 2 ] . morever , one can refer to @xcite and verify that assumption [ assumption one ] is satisfied . it then follows , using theorem [ theorem major result ] , that for all @xmath169 @xmath195 \leq 4k n^{-\frac{2}{3}},\ ] ] in other words , the law of an individual neuron converges to its limit as @xmath196 at the time - uniform rate given above . 12 j. baladron , d. fasoli , o. faugeras , and j. touboul , _ mean - field description and propagation of chaos in networks of hodgkin - huxley and fitzhugh - nagumo neurons _ , the journal of mathematical neuroscience , 2 ( 2012 ) . f. bolley , i. gentil , and a. guillin , _ uniform convergence to equilibrium for granular media _ , archive for rational mechanics and analysis , 208 ( 2013 ) , pp . 429 - 445 . m. bossy , o. faugeras , and d. talay , _ clarification and complement to mean - field description and propagation of chaos in networks of hodgkin - huxley and fitzhugh - nagumo neurons _ , report , hal inria , 2015 . bressloff , _ spatiotemporal dynamics of continuum neural fields _ , journal of physics a : mathematical and theoretical , 45 ( 2012 ) . j. a. carillo , r. j. mccann , and c. villani,_kinetic equilibration rates for granular media and related equations : entropy dissipation and mass transportation estimates _ , revista matematica iberoamericana , 19 ( 2003 ) , pp . 971 - 1018 . p. cattiaux , a. guillin , and f. malrieu , _ probabilistic approach for granular media equa- tions in the non - uniformly convex case _ , probability theory and related fields , ( 2008 ) . s. coombes , _ large - scale neural dynamics : simple and complex _ , neurolmage , 52 ( 2010),pp . 731 - 739 . g. deco , v . k. jirsa , p. a. robinson , m. breakspear , and k. friston , _ the dynamic brain : from spiking neurons to neuralmasses and cortical fields _ , plos comput . biol . , 4 ( 2008 ) . a. destexhe and t. j. sejnowski,_the wilson - cowan model _ , 36 years later , biological cybernetics , 101 ( 2009 ) , pp . 1 - 2 . w. gerstner and w. kistler , _ spiking neuron models _ , cambridge university press , 2002 . d. hansel and h. sompolinsky , _ chaos and synchrony in a model of a hypercolumn in visual cortex _ , journal of computational neuroscience , 3 ( 1996 ) , pp . f. malrieu , _ logarithmic sobolev inequalities for some nonlinear pde s _ , stochastic processes and their applications , 95 ( 2001 ) , pp . 109 - 132 . x. mao , _ stochastic differential equations and applications _ , horwood , 2008 , 2nd edition . del moral and l. miclo , _ branching and interacting particle systems approximations of feynman - kac formulae with applications to non - linear filtering , in sminaire de probabilits xxxiv _ , j. azma , m. emery , m. ledoux , and m. yor , eds . 1729 , springer- verlag berlin , 2000 . del moral and e. rio , _ concentration inequalities for mean field particle models _ , annals of applied probability , ( 2011 ) . del moral and j. tugaut , _ uniform propagation of chaos for a class of inhomogeneous diffusions _ , tech . report , hal inria , 2014 . a. sznitman , _ topics in propagation of chaos , in ecole dt de probabilits de saint - flour xix-1989 , donald burkholder , etienne pardoux , and alain - sol sznitman , eds _ , vol . 1464 of lecture notes in mathematics , springer berlin / heidelberg , 1991 , pp . 165 - 251 . j. touboul , _ the propagation of chaos in neural fields _ , the annals of applied probability , 24 ( 2014 ) . visual cortex , journal of computational neuroscience , 3 ( 1996 ) , pp . j. touboul and b. ermentrout , _ finite - size and correlation - induced effects in mean - field dynamics _ , j comput neurosci , 31 ( 2011 ) , pp.453 - 484 . a. yu veretennikov,_on ergodic measures for mckean - vlasov stochastic equations _ , monte - carlo and quasi - monte - carlo methods , ( 2006 ) , pp . 471 - 486 . wilson and j.d . cowan,_excitatory and inhibitory interactions in localized polulations of model neurons _ , biophys . j. , 12 ( 1972),pp . 1 - 24 .

in this paper we obtain time uniform propagation estimates for systems of interacting diffusion processes . using a well defined metric function @xmath0 , our result guarantees a time - uniform estimates for the convergence of a class of interacting stochastic differential equations towards their mean field equation , and this for a general model , satisfying various conditions ensuring that the decay associated to the internal dynamics term dominates the interaction and noise terms . our result should have diverse applications , particularly in neuroscience , and allows for models more elaborate than the one of wilson and cowan , not requiring the internal dynamics to be of linear decay . an example is given at the end of this work as an illustration of the interest of this result . stochastic differential equation , mean fields , mckean - vlasov equations , interacting diffusion , uniform propagation of chaos , neural network . 60k35 , 60j60 , 60j65 , 92b20

SECTION 1. SHORT TITLE. This Act may be cited as the ``School Food Fresh Act of 2007''. SEC. 2. DEFINITIONS. In this Act: (1) Commodity program.--The term ``commodity program'' means any of-- (A) the commodity supplemental food program established under section 5 of the Agriculture and Consumer Protection Act of 1973 (7 U.S.C. 612c note; Public Law 93-86); (B) the food distribution program on Indian reservations established under section 4(b) of the Food Stamp Act of 1977 (7 U.S.C. 2013(b)); (C) the emergency food assistance program established under the Emergency Food Assistance Act of 1983 (7 U.S.C. 7501 et seq.) and section 27 of the Food Stamp Act of 1977 (7 U.S.C. 2036); (D) the school lunch program established under the Richard B. Russell National School Lunch Act (42 U.S.C. 1751 et seq.); (E) the summer food service program for children established under section 13 of that Act (42 U.S.C. 1761); (F) the child and adult care food program established under section 17 of that Act (42 U.S.C. 1766); and (G) the school breakfast program established under section 4 of that Act (42 U.S.C. 1773). (2) Department.--The term ``Department'' means the Department of Agriculture. (3) Secretary.--The term ``Secretary'' means the Secretary of Agriculture. (4) Task force.--The term ``Task Force'' means the multiagency task force established under section 3(a). SEC. 3. MULTIAGENCY TASK FORCE. (a) In General.--The Secretary shall establish, in the office of the Under Secretary for Food, Nutrition, and Consumer Services, a multiagency task force for the purpose of providing coordination and direction for commodity programs. (b) Composition.--The Task Force shall be composed of at least 4 members, including-- (1) a representative from the Food Distribution Division of the Food and Nutrition Service, who shall-- (A) be appointed by the Under Secretary for Food, Nutrition, and Consumer Services; and (B) serve as Chairperson of the Task Force; (2) at least 1 representative from the Agricultural Marketing Service, who shall be appointed by the Under Secretary for Marketing and Regulatory Programs; (3) at least 1 representative from the Farm Services Agency, who shall be appointed by the Under Secretary for Farm and Foreign Agricultural Services; and (4) at least 1 representative from the Food Safety and Inspection Service, who shall be appointed by the Under Secretary for Food Safety. (c) Duties.-- (1) In general.--The Task Force shall be responsible for evaluation and monitoring of the commodity programs to ensure that the commodity programs meet the mission of the Department-- (A) to support the United States farm sector; (B) to comply with the most recent Dietary Guidelines for Americans published under section 301 of the National Nutrition Monitoring and Related Research Act of 1990 (7 U.S.C. 5341); and (C) to contribute to the health and well-being of individuals in the United States through the distribution of domestic agricultural products through commodity programs. (2) Specific duties.--In carrying out paragraph (1), the Task Force shall-- (A) review and make recommendations regarding the specifications used for the procurement of food commodities, taking into consideration recommendations based on the results of evaluations carried out using grants made available under section 4; (B) review and make recommendations regarding the effective distribution of food commodities; (C) review and make recommendations regarding efficient and effective systems to ensure the best use of Federal funds to maximize the quantity and quality of foods purchased for recipient agencies and the best use of those purchased foods by recipient agencies; and (D) on the request of the Secretary, review and make recommendations regarding future updates of the Dietary Guidelines for Americans published under section 301 of the National Nutrition Monitoring and Related Research Act of 1990 (7 U.S.C. 5341). (d) Report.--Not later than 1 year after the date of enactment of this Act, and annually thereafter, the Secretary shall submit to Congress a report that describes, for the period covered by the report-- (1) the findings and recommendations of the Task Force; and (2) policies implemented for the betterment of commodity programs. SEC. 4. GRANTS FOR SPECIFICATION DEVELOPMENT. (a) In General.--Not later than 1 year after the date of enactment of this Act, the Secretary shall provide 5 competitive grants to nonprofit research institutions (including research universities) selected by the Secretary for use in evaluating the product specifications of food commodity products procured through commodity programs to determine-- (1) the consistency of those specifications with the nutritional goals of the commodity program; (2) the acceptability of the products procured under the specifications by recipient agencies and consumers; and (3) the extent to which food commodities purchased through commodity programs are comparable to any commercial counterparts to those commodities. (b) Types of Grants.--Of the 5 grants provided under subsection (a), a grant shall be provided for the evaluation and recommendation of product specifications for each of the categories of-- (1) fruits and vegetables; (2) meat; (3) poultry; (4) grains, nuts, and oils; and (5) dairy products. (c) Report.--Not later than 18 months after the date on which the Secretary provides a grant under this section, the recipient of the grant shall submit to the Secretary and the Task Force a report that-- (1) describes the results of evaluations carried out using funds from the grant; and (2) includes recommendations based on those results. (d) Authorization of Appropriations.--There is authorized to be appropriated to carry out this section $2,500,000. SEC. 5. USDA SCHOOL FOOD FRESH PROGRAM. Section 10603 of the Farm Security and Rural Investment Act of 2002 (7 U.S.C. 612c-4) is amended to read as follows: ``SEC. 10603. PURCHASE OF SPECIALTY CROPS. ``(a) Definitions.--In this section: ``(1) Fruits, vegetables, other specialty food crops.--The terms `fruits', `vegetables', and `other specialty food crops' shall have the meaning given the terms by the Secretary of Agriculture. ``(2) Secretary.--The term `Secretary' means the Secretary of Agriculture. ``(3) Service institution.--The term `service institution' has the meaning given the term in section 13(a) of the Richard B. Russell National School Lunch Act (42 U.S.C. 1761(a)). ``(b) Purchase Authority.--Of the funds made available under section 32 of the Act of August 24, 1935 (7 U.S.C. 612c), for fiscal year 2008 and each subsequent fiscal year, the Secretary shall use not less than $200,000,000 each fiscal year to purchase fruits, vegetables, and other specialty food crops. ``(c) USDA School Food Fresh Program.-- ``(1) Definition of eligible product.--In this subsection, the term `eligible product' means a fruit or vegetable item that-- ``(A) is offered by a vendor approved by the Secretary under paragraph (4); ``(B) is fresh, dried, or frozen in a manner that maximizes retention of nutrient density; and ``(C) to the maximum extent practicable, reflects local preferences and supports local agriculture. ``(2) Agreements.--The Secretary, acting through such regional procurement offices of the Department of Agriculture as the Secretary determines to be appropriate, shall carry out a program under which the Secretary shall enter into agreements with local and regional distributors to supply eligible products to schools and service institutions. ``(3) Funds.--Eligible products supplied under an agreement described in paragraph (2) shall be purchased by schools and service institutions using funds that are allocated to the schools or service institutions for the purpose of-- ``(A) purchasing fruits and vegetables; or ``(B) providing nutritious meals. ``(4) Vendors.-- ``(A) In general.--A local or regional distributor of eligible products that seeks to supply eligible products to schools and service institutions under this subsection shall apply to the Secretary for approval as a participating vendor. ``(B) Conditions for approval.--The Secretary shall approve a vendor as eligible to supply eligible products under this subsection if the vendor-- ``(i) demonstrates the ability to supply those eligible products; ``(ii) complies with standards for food safety developed by the Secretary; ``(iii) consistently provides products that meet standards of grade, size, freshness, and quality as required by the Secretary or a local procurement officer; and ``(iv) demonstrates the ability to supply eligible products from local growers and processors. ``(C) Monitoring.-- ``(i) In general.--The Secretary shall develop and implement a system for monitoring vendors approved under this paragraph. ``(ii) Certification.--A monitoring system under clause (i) may include a requirement to obtain certification-- ``(I) in accordance with a program designed by the Secretary; and ``(II) for which the Secretary may require compensation. ``(5) Funding.-- ``(A) In general.--Of the amount specified in subsection (b), the Secretary shall use not less than $50,000,000 each fiscal year for the purchase of eligible products for distribution to schools and service institutions in accordance with section 6(a) of the Richard B. Russell National School Lunch Act (42 U.S.C. 1755(a)). ``(B) Additional available funds.--A school or service institution that uses an agreement described in paragraph (2) to purchase eligible products may allocate up to 30 percent of the funds of the school or service institution authorized under section 6 of the Richard B. Russell National School Lunch Act (42 U.S.C. 1755), and such additional funds as are necessary from funds allocated to the school or service institution under sections 4 and 11 of that Act (42 U.S.C. 1753, 1759a), for the purpose of procuring eligible products through vendors approved by the Secretary under paragraph (4). ``(C) Authorization of appropriations for administrative expenses.--There are authorized to be appropriated such sums as are necessary to pay administrative costs incurred in carrying out this subsection.''. SEC. 6. USE OF COMMODITY ENTITLEMENT FUNDS. (a) In General.--The Secretary shall, to the maximum extent practicable, purchase for commodity programs foods that are in the least-processed state. (b) Processing of Foods.--The Secretary, upon the approval of national processing agreements, shall make available to all schools and other recipient agencies the opportunity to divert unprocessed or minimally-processed commodity foods to subsequent processors for conversion into usable end products.

School Food Fresh Act of 2007 - Directs the Secretary of Agriculture to establish in the office of the Under Secretary for Food, Nutrition, and Consumer Services a task force to coordinate commodity programs. Directs the Secretary to provide five (for each of five specified food categories) competitive grants to nonprofit research institutions to evaluate commodity program products to determine: (1) consistency with program nutritional goals; (2) product acceptability by recipient agencies and consumers; and (3) commercial counterpart comparability. Amends the the Farm Security and Rural Investment Act of 2002 to direct the Secretary to: (1) enter into agreements with qualifying local and regional distributors to supply fruit and vegetable items to schools and service institutions; and (2) implement a vendor monitoring program. Directs that the Secretary: (1) to the maximum extent practicable, purchase for commodity programs foods that are in their least-processed state; and (2) upon the approval of national processing agreements, make available to all schools and other recipient agencies the opportunity to divert unprocessed or minimally-processed commodity foods to subsequent processors for end product conversion.

in 1970 , vitaly efimov found a remarkable effect in the quantum spectrum of three particles @xcite . he considered particles interacting through short - range attractive interactions that are nearly resonant . by _ short range _ , one means interactions decaying faster than @xmath2 where @xmath3 is the interparticle distance , and by _ nearly resonant _ , one means attractive interactions that can almost or just barely support a weakly two - body bound state . the fact that , in quantum mechanics , an attractive interaction may be too weak to bind two particles is due the quantum fluctuations of the kinetic energy ( also known as the zero - point energy ) that competes with the attractive interaction . when the interaction is just strong enough to cancel the repulsive effect of the kinetic energy , the interaction is said to be resonant because two particles scattering at low energy are very close to binding during their collision : they spend a long time together ( they `` resonate '' ) before separating , which is characterised in scattering theory by an @xmath4-wave scattering length that is much larger than the range of the interactions . under these conditions , vitaly efimov found that an effective long - range three - body attraction arises , and this attraction may support an infinite family of three - body bound states ( called efimov states or efimov trimers ) , in which the three particles are bound at larger and larger distances , beyond the range of the interactions . the efimov effect , as it became known , is striking in several aspects : [ [ induced - long - range - interaction ] ] induced long - range interaction + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + even though the interactions are short - ranged , the three particles feel a long - range three - body attraction . this seemingly counter - intuitive situation can be explained by the fact that an effective interaction is mediated between two particles by the third particle moving back and forth between the two . it is thus possible for the three particles to feel their influence at distances much larger than the range of interactions , typically up to distances on the order of the scattering length . [ [ discrete - scale - invariance ] ] discrete scale invariance + + + + + + + + + + + + + + + + + + + + + + + + + right at the resonance , the scattering length is infinite and the effective attraction extends to infinite distances . being of kinetic origin ( the exchange of a particle between two others ) , the attraction scales like the kinetic energy of the particles and brings no characteristic length scale . as a result , the three - body system is scale invariant . quantisation in this attractive potential gives an infinite series of bound states , the efimov trimers , whose properties such as size and energy are related to each others by a fixed scale transformation . the energy spectrum , for instance , forms a geometric series with an accumulation at the zero energy threshold , corresponding to infinitely weakly bound states . this situation is referred to as the `` discrete scale invariance '' of efimov states . efimov states thus look like a infinite family of matryoshka , the russian wooden dolls that can be nested inside each other . this image was originally given to describe renormalisation - group limit cycles @xcite , which constitute a possibility among the general classification of renormalisation - group limits , originally proposed by kenneth g. wilson @xcite . this possibility , which exhibits discrete scale invariance , is indeed realised in systems exhibiting the efimov effect @xcite two - body interactions @xcite such as an electron scattering off an excited hydrogen atom . a more general discussion on discrete scale invariance is given in ref . @xcite . ] . [ [ borromean - binding ] ] borromean binding + + + + + + + + + + + + + + + + + when the interaction is not strong enough to support a two - body bound state , it may nonetheless support one , up to infinitely many , efimov trimers . this possibility of binding @xmath5 particles , while the @xmath6 subsystems are unbound is called `` borromean '' binding and use the term brunnian for larger @xmath5 . ] . this denomination derives from the ancient symbol of intricated circles called borromean rings , which have been used , among others , by the borromeo family in their coat of arms . borromean rings are arranged in such a way that they can not be separated , although cutting one of them sets the others free . they therefore constitute a classical example of borromean binding . in this case , the binding is due to their specific topology . in the case of quantum particles , however , borromean binding is possible even if the interparticle interaction is isotropic and does not enjoy such topological properties . although it is counterintuitive from a classical point of view , it may be understood by considering that the number of degrees of freedom providing a zero - point kinetic energy scales like @xmath5 whereas the number of pairwise interactions scales like @xmath7 , making the interactions win for sufficiently large @xmath5 . efimov trimers are an example of this phenomenon for @xmath8 . more difficult to interpret is the fact that when the interaction is strong enough to support a two - body bound state , further increasing the interaction reduces the binding of the three - body bound state with respect to that of the two - body bound state . + in recent years , it has been realised that the efimov effect gives rise to a broad class of phenomena that have been referred to as _ efimov physics_. consequences and extensions of the efimov effect have indeed been found in systems of various kinds of particles , from three to many particles , with various kinds of interactions and in various mixtures of dimensions . the denomination `` efimov physics '' is however not clearly defined and somewhat subjective . even the notion of what constitutes an efimov state has been debated and considerably extended by some authors - see section [ subsec : what - is - an - efimov - state ] . in the strictest sense , `` efimov physics '' designates physics that is a direct consequence of the occurence of the efimov effect . more generally speaking , one may say that a system exhibits efimov ( or efimov - like ) physics when a three - or - more - body attraction emerges from short - range interactions and possibly exhibits some kind of discrete scale invariance . the purpose of this review is to cover the recent theoretical and experimental advances in efimov physics , taken in its broadest sense . efimov physics is not only remarkable for its distinctive properties , it is also part of what is often referred to as the _ universality _ of low - energy physics . when a physical system with short - range interaction has a sufficiently low energy , its wave function is so delocalised that many microscopic details of the interactions become irrelevant , and most of its properties can be effectively described by a few parameters . such physics is universal as it can be applied to many different systems , regardless of their microscopic details . efimov physics is an example of such a situation , as it involves states in which the particles are on average at larger separations than the range of their interactions . for instance the discrete scale invariance of efimov states is a universal feature that depends only on a few general properties such as the particles masses and quantum statistics . as a result of this universality , efimov physics applies to virtually any field of quantum physics , be it atomic and molecular physics @xcite , nuclear physics @xcite , condensed matter @xcite or even high - energy physics @xcite . interestingly , thanks to the formal connection between quantum theory and statistical physics , it may also apply to the thermal equilibrium of classical systems , such as three - stranded dna @xcite . the universality of efimov physics does not mean that it occurs in any system . it means that any system meeting the conditions for its appearance exhibits the same universal features . these conditions turn out to be quite restrictive , which is why it has taken around forty years since the original theoretical prediction of the efimov effect to obtain convincing experimental confirmations . generally speaking , the efimov effect requires resonant short - range interactions . such interactions are rare , because they require a bound or virtual state to exist accidentally just below the scattering threshold of two particles . this situation turns out to be common in nuclear physics , but most nuclear particles obey fermi statistics , and the pauli exclusion between fermions overcomes the efimov attraction in most cases , preventing the efimov effect from occurring . on the other hand , bosonic particles or excitations are common in various fields of physics , but their interaction is rarely resonant . nevertheless , there are now a significant number of physical systems where efimov physics has been observed or is expected to be observed . in particular , with the advent of controllable feshbach resonances in ultra - cold atomic gases it has become possible to fulfill at will the conditions for the occurence of efimov physics , and study it extensively . since there have been many theoretical developments in efimov physics recently , this review is organised from the theoretical point of view in terms of physical situations leading to efimov or efimov - like physics . for each situation , the current state of experimental observation in different fields of physics is presented . although this choice of presentation requires the reader to read different sections to know about the experimental achievements in a particular field , it should give a comprehensive overview of what has , and what has not yet , been observed in efimov physics . the sections are relatively independent , so that the reader can jump directly to the situation of their interest . as for the readers who desire to grasp the bare essentials of the efimov effect , we have included a concise derivation of efimov theory in section [ subsec : efimov - theory ] and discussed the main features of efimov states in section [ subsec : what - is - an - efimov - state ] . in addition , we give in the following section a short history of the development of efimov physics underlining the landmarks contributions . history of efimov physics from the original theoretical prediction by vitaly efimov to the latest experimental observations , along with the number of related publications ( source : web of knowledge ) . ] in 1970 , vitaly efimov was working as a junior researcher at the ioffe institute in leningrad , where he had completed his doctoral thesis four years earlier . following the seminal work of llewellyn h. thomas in 1935 @xcite and later works by skorniakov and ter - martirosian @xcite , he was interested in the three - body problem in quantum mechanics to describe nuclear systems such as the triton ( the nucleus of tritium , made of one proton and two neutrons ) . thomas had shown that three particles with a symmetric wave function , unlike two particles , can be bound with arbitrarily large binding energy for sufficiently small range of the interparticle attractive force . this finding , referred to as the `` thomas collapse '' or `` fall to the centre '' seemed somewhat peculiar , but allowed thomas to estimate a lower bound for the range of nuclear forces from the measured energy of tritium , before it was confirmed by neutron - proton scattering experiments . using the hyper - spherical coordinates , efimov found that when two of the particles can nearly bind , the three particles actually admit an infinite series of bound states of ever - increasing sizes , instead of just one as previously anticipated . this was due to an effective three - body attractive force , which gave a simple interpretation for the thomas collapse . he published his result in both the soviet literature @xcite and western journals @xcite where it became known as the `` efimov effect '' . the first publication in english did not provide the derivation and the effect was thus met with skepticism . however , it prompted some theorists to look into the problem and soon after , the validity of efimov s result was confirmed both analytically and numerically by r. d. amado and j. v. noble @xcite . for a long time , however , the efimov effect was regarded by many as a theoretical peculiarity of the formal three - body problem that would have little to virtually no observable consequences on real physical systems . on the other hand , some people took the effect seriously and tried to find physical systems where it could be observed . vitaly efimov proposed in his original papers that the efimov effect could describe nuclear systems such as the triton and the famous hoyle state of carbon-12 . subsequently , it was suggested that the efimov effect may be revealed in some hypernuclei by t. k. lim in 1986 @xcite , and in halo nuclei by dmitri v. fedorov , aksel s. jensen , and karsten riisager in 1994 @xcite . the proposed nuclear systems indeed feature resonant two - body subsystems , which is a requirement for the efimov effect to occur . the closer to resonance the two - body subsystems are , the larger the number of three - body bound states . however , having more than one three - body bound state requires a very close tuning near the resonance , something that happens only accidentally in nature . as a result , the proposed nuclear systems allow only one three - body bound state to exist , and do not reveal the infinity of other states predicted by the efimov theory closer to resonance . moreover , it is difficult to show that such a single three - body bound state originates from the efimov effect for two reasons . first , efimov s theory relies on an unknown three - body parameter to describe the three - body states , and is thus not quite predictive for the properties of a single three - body state , whereas it makes definite and universal predictions ( independent of the three - body parameter ) for the relative properties of two three - body states . second , the first three - body state is the smallest of the efimov series and is significantly affected by the details of the interparticle forces , to the point that it is debatable to call it efimov state . because of these ambiguities , and despite the experimental observations of the proposed nuclear systems , it has been difficult to prove or disprove that they are indeed efimov states . to obtain better experimental evidence of the efimov effect , researchers turned to other kinds of particles for which the two - body resonance condition could be more closely fulfilled . seven years after efimov s theory , t. k. lim already pointed out the particular case of helium-4 atoms @xcite , whose interatomic interaction is close enough to resonance to admit two three - body bound states , as was checked subsequently by many few - body theorists . this prompted a decade - long experimental search for these two helium-4 trimer states by the group of jan peter toennies in gttingen , by analysing diffracted beams of helium-4 clusters @xcite . while the ground - state trimer could be observed , the excited trimer state , which is regarded as a true efimov trimer and an evidence of the efimov effect , could not be observed . the breakthrough that established efimov physics came from the field of ultra - cold atoms . in the 1990s , it was predicted @xcite and demonstrated experimentally @xcite that the interactions between atoms could be controlled and brought to resonance by applying a magnetic field . this led to the proposal by brett d. esry , chris h. greene , and james p. burke jr @xcite to observe the signatures of efimov states in such systems . such experimental signature of a three - body state near the two - body resonance of cesium-133 atoms was obtained in 2002 in the group of hanns - christoph ngerl and rudolf grimm in innsbruck , and after careful analysis reported in 2006 @xcite . although it revealed only one trimer , as in the nuclear systems or the previous experiments on helium , its efimovian nature appeared more convincing due to its borromean nature ( the trimer exists in a region where two - body subsystems are known to be unbound ) . this landmark experiment opened the way for a systematic investigation of efimov physics , because the interaction could now be controlled . this led to many similar experimental results from various laboratories around the world using other species of ultra - cold atoms ( in particular during the year 2009 ) as well as an intense theoretical activity to understand and explore various aspects of efimov physics in ultra - cold atoms . in the same year , universal four - body bound states tied to efimov states were evidenced in the cesium experiment in innsbruck by francesca ferlaino and co - workers @xcite , just after being predicted by theorists @xcite . the year 2009 culminated with the itamp workshop in rome entitled efimov 2009 , where the wealth of new experimental and theoretical results was presented . with the accumulation of experimental results in ultra - cold atoms , the theoretically unknown three - body parameter of the efimov theory could be obtained from experimental measurements for many different efimov states . in particular , it could be compared for different two - body resonances in the lithium-7 experiments by the group of lev khaykovich at bar - ilan university , and in the cesium experiments by the group of innsbruck @xcite . to everyone s surprise , the three - body parameter was found to be nearly the same for all the resonances of a given atomic species . it even appeared to be universally correlated to the van der waals of the atoms , while it was thought to depend on many other microscopic details . this so - called van der waals universality of the three - body parameter was later explained by theoretical works @xcite , which showed that a sudden deformation of the trimer configuration prevents the three atoms from reaching separations smaller than the van der waals length , making the trimers insensitive to more microscopic features of the interatomic interaction . while different measurements of three - body recombination and atom - dimer relaxation provided several experimental points in the three - body spectrum confirming the `` scenario'' obtained by vitaly efimov , the most striking aspect of this scenario , namely the discrete scale invariance leading to the geometric series of three - body bound states was not confirmed clearly since the experiments did not reveal consecutive three - body bound state . observing consecutive efimov states is an experimental challenge since each new state is by definition much larger in size with a much weaker binding energy . this endeavour was ultimately successful in 2014 , when the experimenters in innsbruck managed to observe a second efimov state of cesium atoms by pushing the limits of their experiment @xcite , while the groups of cheng chin at the university of chicago @xcite and matthias weidemller at the university of heidelberg @xcite independently observed up to three efimov states of two cesium and one lithium atoms , whose energy levels were predicted to be closer to each other due to the large mass imbalance between these two atomic species . the same year , outside the ultra - cold atom community , the group of reinhard drner in frankfurt could finally observe the long - sought second trimer of helium-4 by the coulomb explosion imaging technique , a result published the following year @xcite . not only this brought further experimental confirmation of the efimov effect , it also provided the first spatial imaging of an efimov state . one may say that the year 2014 concluded a 44-year - long search for a full confirmation of the efimov effect . the history of this search is summarised in fig . [ fig : history - of - efimov ] where landmark contributions are indicated . the simplest situation for which efimov physics occurs corresponds to three identical bosons interacting via resonant short - range interactions . in section [ subsec : efimov - theory ] , we briefly present the corresponding theory originally proposed by vitaly efimov and its extensions for finite - range interactions . in the following sections , we review the experimental observations and prospects for observations of bosonic efimov states in nuclear , atomic , and condensed matter systems . we consider identical bosonic particles of mass @xmath9 , with no internal degree of freedom , interacting via short - range two - body ( and possibly three - body ) interactions . here , _ short - range _ interactions means that the interaction potentials decay faster than @xmath2 , where @xmath3 is the separation between two particles . in this situation , there exists a separation @xmath10 , called the range of the interaction , beyond which the relative motion of two particles is almost free . it is in this asymptotically free region where the particles energy is purely kinetic that the efimov effect takes its roots , and that is why it is universal . although the relative motion of two particles is free in this region , each angular partial wave of the wave function @xmath11 describing the two - body relative motion has a phase shift @xmath12 with respect to the non - interacting wave function , as a result of the particles interacting at shorter separation . namely , in the partial - wave expansion of @xmath11 , @xmath13 where @xmath14 are the legendre polynomials , the partial wave component @xmath15 has the form , @xmath16 where @xmath17 is the relative wave number between the two particles . in the absence of interaction , the phase shift @xmath18 ( no scattering occurs ) . on the opposite , the strongest dephasing the interaction can induce is @xmath19 ( modulo @xmath20 ) , in which case the interaction is said to be _ resonant _ in that partial wave . efimov physics arises when the two - body interaction is near - resonant in the @xmath4-wave partial wave ( @xmath21 ) , which means that the phase shift @xmath22 of the @xmath4 wave is close to @xmath23 ( modulo @xmath20 ) . [ [ the - scattering - length ] ] the scattering length + + + + + + + + + + + + + + + + + + + + + it is well - known from scattering theory @xcite that at low scattering energy ( @xmath24 ) , only the @xmath4 wave is scattered , i.e. has a non - zero phase shift . moreover , the phase shift can be written as @xmath25 where @xmath26 defines the _ _ scattering length__. therefore , for the two - body interaction to be resonant at low energy , the scattering length @xmath26 has to be much larger than @xmath10 : @xmath27 in particular , the limit @xmath28 is sometimes called the _ unitary limit _ or _ unitarity _ , because in this limit the factor @xmath29 in the expression of the scattering cross section @xmath30 , approaches its maximal value @xmath31 . this maximum of the scattering cross section is the consequence of a fundamental property of quantum mechanics , the unitarity of the s - matrix . it can be reached precisely for resonant interactions . near unitarity , the scattering length @xmath26 is the only parameter that controls the physics of two particles at low energy , either positive or negative : it determines the cross section for scattering states ( positive energy ) , and the binding energy of a weakly bound state below the break - up threshold ( negative energy ) . this bound state , also called _ dimer _ , exists only for a positive scattering length and its binding energy is close to @xmath32 where @xmath9 is the mass of the particles and @xmath33 is the reduced planck constant . the resonance of the interaction is therefore related to the appearance of the two - body bound state from below the scattering threshold exactly at the unitary limit @xmath34 . it is represented by a black line in fig . [ fig : efimovplot ] . [ [ zero - range - theory ] ] zero - range theory + + + + + + + + + + + + + + + + + short - range near - resonant interactions at low energy constitute a limit that can be treated by the zero - range theory . this theory assumes that the short - range region where the interaction directly affects the wave function can be neglected and only the asymptotically free region that is parameterised by the scattering length is relevant . this amounts to saying that the range @xmath10 of the interaction is vanishingly small compared to the scattering length @xmath26 or wave length @xmath35 of the particles . this can be implemented in various ways . a first way is to consider a simple interaction potential with a finite range @xmath10 , calculate observables , and take the limit @xmath36 for a fixed scattering length @xmath26 . another way is to consider a zero - range pseudopotential , such as a contact interaction represented by a delta function potential , sometimes referred to as a `` fermi pseudopotential '' @xcite . this introduces ultraviolet divergences in exact calculations which have to be renormalised to obtain observables @xcite . renormalisation can be implemented by introducing a cut - off in momentum space @xcite , or regularising the delta function using the lee - huang - yang pseudopotential @xcite : @xmath37 yet another way is to consider the system as free ( no interaction ) and impose the so - called bethe - peierls boundary condition @xcite on the many - particle wave function @xmath38 when any two particles separated by @xmath3 come in contact : @xmath39{}\frac{1}{a}\label{eq : bethepeierls}\ ] ] the essence of all these methods is to correctly reproduce the form of the two - body wave function in the region @xmath40 , @xmath41 which can be obtained from eqs . ( [ eq : partialwaveexpansion ] ) , ( [ eq : partialwave ] ) and ( [ eq : swavephaseshift ] ) . the zero - range methods make the simplification that this form remains true down to @xmath42 , although this is unphysical for @xmath43 . such zero - range methods can be directly implemented in the schrdinger equation describing the three - boson system @xcite , or alternative formalisms such as integral equations @xcite , functional renormalisation equations @xcite , and effective field theory @xcite . here , we will make use of the schrdinger equation along with the bethe - peierls boundary condition eq . ( [ eq : bethepeierls ] ) . we should note that vitaly efimov s original derivation @xcite did not invoke explicitly a zero - range interaction , but instead considered eq . ( [ eq : twobodywavefunction ] ) , i.e. the effect of the resonant interaction outside its range @xmath10 , without requiring @xmath36 . as we shall see , the zero - range theory for three particles is in fact ill - defined . the more physical approach of efimov avoids this difficulty and naturally introduces the three - body parameter . it should thus be referred to as a universal theory , instead of a zero - range theory . nevertheless , it is essentially equivalent to the zero - range theory cured by a three - body boundary condition . for the sake of simplicity , we will take this path , which formally follows very closely efimov s original derivation . [ [ derivation - of - the - efimov - attraction ] ] derivation of the efimov attraction + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + for three bosons located at @xmath44 , @xmath45 and @xmath46 , one can eliminate the centre of mass , and the system can be described by two vectors , called _ jacobi coordinates _ : @xmath47 where @xmath48 are to be chosen among ( 1,2,3 ) . there are thus three possible jacobi coordinate sets , shown in fig . [ fig : jacobi ] , which are related as follows : @xmath49 @xmath50 choosing one set of jacobi coordinates , the time - independent three - body wave function satisfies the free schrdinger equation at total energy @xmath51 : @xmath52 along with the bethe - peierls boundary condition eq . ( [ eq : bethepeierls ] ) for all pairs of bosons . because of the bosonic exchange symmetry , the wave function @xmath38 can be decomposed as follows : @xmath53 where the function @xmath54 ( known as faddeev component @xcite ) satisfies the equation : @xmath55 applying the bethe - peierls boundary condition eq . ( [ eq : bethepeierls ] ) for the pair ( 1,2 ) to eq . ( [ eq : faddeevdecomposition ] ) , one obtains : @xmath56_{r\to0}+\chi\!\left(\!\!\!\begin{array}{c } \frac{\sqrt{3}}{2}\vec{\rho},-\frac{1}{2}\vec{\rho}\end{array}\!\!\!\right)+\chi\!\left(\!\!\!\begin{array}{c } -\frac{\sqrt{3}}{2}\vec{\rho},-\frac{1}{2}\vec{\rho}\end{array}\!\!\!\right)\\ = \left[\!-\frac{r}{a}\left(\chi(\vec{r},\vec{\rho})+\chi\!\left(\!\!\!\begin{array}{c } \frac{\sqrt{3}}{2}\vec{\rho},-\frac{1}{2}\vec{\rho}\end{array}\!\!\!\right)+\chi\!\left(\!\!\!\begin{array}{c } -\frac{\sqrt{3}}{2}\vec{\rho},-\frac{1}{2}\vec{\rho}\end{array}\!\!\!\right)\right)\!\right]_{r\to0}\label{eq : bethepeierlsjacobi}\end{gathered}\ ] ] where @xmath57 and @xmath58 . from the bosonic exchange symmetry , the same equation is obtained by applying the bethe - peierls boundary condition for the other two pairs . in the right - hand side of eq . ( [ eq : bethepeierlsjacobi ] ) , only the first term remains when @xmath59 , because @xmath60 diverges for @xmath59 but is finite elsewhere . the function @xmath54 can be expanded in partial waves , which can be shown to be independent in the zero - range theory . the efimov effect for bosons occurs in the partial - wave channel with total angular momentum @xmath61 . in this channel , @xmath54 is independent of the directions of @xmath62 and @xmath63 and can be written as @xmath64 @xmath65 is finite for @xmath59 , consistent with the divergence of @xmath54 , but must satisfy : @xmath66{}0\label{eq : condition1}\ ] ] to keep @xmath54 finite in this limit . inserting eq . ( [ eq : swavechi ] ) into eqs . ( [ eq : freeschrodingereqchi ] ) and ( [ eq : bethepeierlsjacobi ] ) yields the equation @xmath67 and the boundary condition for @xmath59 : @xmath68_{r\to0}+2\frac{1}{\frac{\sqrt{3}}{4}\rho}\chi_{0}\!\left(\!\!\!\begin{array}{c } \frac{\sqrt{3}}{2}\rho,\frac{1}{2}\rho\end{array}\!\!\!\right)=\!-\frac{1}{a}\chi_{0}(0,\rho)\!\label{eq : bethepeierlsjacobi-1}\ ] ] one can finally perform a transformation of the coordinates ( @xmath69 ) to the polar coordinates @xmath70 known as hyper - spherical coordinates @xcite : @xmath71 where @xmath72 is the hyper - radius satisfying @xmath73 and @xmath74 is the delves hyper - angle . in these coordinates , one obtains the equation : @xmath75 with the boundary condition for @xmath76 : @xmath77_{\alpha\to0}+\frac{8}{\sqrt{3}}\chi_{0}\!\left(\!\!\!\begin{array}{c } r,\frac{\pi}{3}\end{array}\!\!\!\right)=\!-\frac{r}{a}\chi_{0}(r,0)\label{eq : hypersphericalcondition}\ ] ] the problem then becomes separable in @xmath72 and @xmath74 , for the case @xmath28 corresponding to the unitary limit . indeed , in this limit the right - hand side of eq . ( [ eq : hypersphericalcondition ] ) vanishes and one is left with a boundary condition at @xmath78 that is independent of @xmath72 . on the other hand , the other boundary condition eq . ( [ eq : condition1 ] ) corresponds to @xmath79 , which is a boundary condition at @xmath80 that is also independent of @xmath72 . one can thus find a solution of eq . ( [ eq : hypersphericalequation ] ) in the form : @xmath81 where @xmath82 satisfies @xmath83 with the boundary conditions at @xmath78 and @xmath84 . this gives the following solutions : @xmath85 where @xmath86 is a solution of the equation : @xmath87 each solution labelled by @xmath88 constitutes a _ channel _ for the hyper - radial motion . that is to say , for each solution @xmath89 there is a corresponding hyper - radial function @xmath90 such that @xmath91 is a solution of eq . ( [ eq : hypersphericalequation ] ) . it satisfies the equation : @xmath92 which can be written as a one - dimensional schrdinger equation : @xmath93 with the hyper - radial potential , @xmath94 all solutions of eq . ( [ eq : transcendentalequation ] ) are real , except one denoted as @xmath95 which is purely imaginary . as a result , the effective @xmath96 potential in eq . ( [ eq : hyperradialequation ] ) is attractive for the channel @xmath97 . this is in contrast with the non - interacting three - body problem , where the boundary condition eq . ( [ eq : hypersphericalcondition ] ) is replaced by @xmath98{}0 $ ] , leading to eq . ( [ eq : hyperangularsolution ] ) with eigenvalues @xmath99 that are all real . in this case , the effective @xmath96 potential eq . ( [ eq : hyperradialpotential ] ) is repulsive for all @xmath88 . this repulsion is interpreted as a generalised centrifugal barrier due to the free motion of deformation of the three - body system . in the interacting problem at unitarity however , the channel @xmath97 leads to an effective three - body attraction @xmath100 this unexpected attraction is the basis for efimov physics and is referred to as the _ efimov attraction_. it can be interpreted as the result of a mediated attraction between two particles by exchange of the third particle . the existence of this attraction shows that the zero - range theory for three bosons is not well defined . indeed , eq . ( [ eq : hyperradialequation ] ) for @xmath97 is a schrdinger equation for an attractive @xmath101 potential , which is scale invariant since a @xmath102 potential scales as the kinetic energy @xmath103 under a scaling transformation @xmath104 . it is known that such an equation admits a solution at any energy , and its spectrum is therefore not bounded from below @xcite . indeed , if the equation admits a solution at energy @xmath105 , making the scaling transformation @xmath104 with an arbitrary scaling factor @xmath106 gives another solution at energy @xmath107 . this means that under the efimov attraction the three - boson system collapses on itself , a phenomenon discovered long ago by llewellyn h. thomas @xcite and referred to as the `` thomas collapse '' or `` fall of the particles to the centre '' . the same problem was found @xcite in the formulation of the zero - range theory for three particles by an integral equation , known as the skorniakov and ter - martorisian equation @xcite . this is of course a shortcoming of the zero - range theory , since the finite - range effects of the interaction can no longer be neglected when the distance between the three bosons becomes comparable with the finite range of interactions . a practical solution to this problem , originally suggested by vladimir n. gribov and demonstrated by g. s. danilov @xcite , consists in imposing a condition on the solutions of the three - body equation , or a momentum cut - off on the equation @xcite , in order to reproduce a known three - body observable , such as a three - body bound state energy or particle - dimer scattering property . for instance , fixing the triton energy to the observed value , and solving the three - body equation with that condition enables the prediction of the neutron - deuteron scattering length @xcite . in vitaly efimov s formulation of the three - body problem in terms of eq . ( [ eq : hyperradialequation ] ) , a similar procedure can be achieved by imposing a boundary condition below some arbitrarily small hyper - radius @xmath108 . thus , in addition to the bethe - peierls two - body boundary condition eq . ( [ eq : bethepeierls ] ) , the three - body problem in the zero - range theory requires an extra three - body boundary condition . this boundary condition can be implemented in various ways , for example setting a hard wall at the hyper - radius @xmath108 where @xmath109 has to vanish , or imposing the value of the logarithmic derivative of @xmath109 at @xmath108 , by analogy to the bethe - peierls condition eq . ( [ eq : bethepeierls ] ) . note that these two implementations are not strictly equivalent : a hard wall prevents the fall to the centre and sets a ground - state energy , whereas a logarithmic derivative condition only makes the spectrum discrete but still unbounded from below ( states below the physically relevant energy are therefore unphysical features ) . in any case , both implementations introduce a new length scale in the problem , which is referred to as the _ three - body parameter_. it is this parameter that fixes the three - body observables . physically , the three - body parameter encapsulates the effects of the two - body ( and possibly three - body ) interactions at short distance . to see how the three - body parameter arises , let us consider the solutions of eq . ( [ eq : hyperradialequation ] ) for @xmath97 . near the small hyper - radius @xmath108 , any solution with sufficiently small energy @xmath110 , is of the form : @xmath111 imposing a boundary condition at @xmath108 imposes a specific ratio @xmath112 . from dimensional analysis , this ratio has units of inverse length @xmath113 to the power @xmath114 . thus , we can write @xmath115 , which can be further expressed as @xmath116 the three - body wave function therefore shows log - periodic ocillations in the hyper - radius , and the phase of these oscillations @xmath117 is given by the new scale @xmath113 ( expressed in some previously fixed unit @xmath118 ) , which is a possible representation of the three - body parameter . schematic representation of the so - called `` efimov plot '' or `` efimov scenario '' showing the discrete scale invariance of the three - body spectrum for identical bosons in the zero - range theory . the wave number @xmath119 associated with the energy @xmath120 of the dimer ( black ) and trimers ( red ) is plotted against the inverse scattering length @xmath121 . the blue and orange filled regions represent the three - body scattering continuum and the particle - dimer scattering continuum , respectively . note that these continua overlap for @xmath122 and @xmath123 . special values of @xmath124 and @xmath121 are indicated by the dots : a trimer appears from the three - body scattering threshold at @xmath125 , has a binding wave number @xmath126 at unitarity , and disappears below the particle - dimer scattering threshold at @xmath127 . trimer resonances in the three - body continuum are indicated by dotted curves . the discrete scale invariance of the spectrum is indicated by the grey arrows showing the universal scaling ratio between consecutive levels . for clarity , the value of the strength @xmath128 has been artificially set to 3 , instead of 1.00624 , thus reducing the spacings between the trimer levels to make them more visible . ] one of the fundamentally new findings of vitaly efimov is that the three - body problem with the three - body boundary condition does not only yield just one three - body bound state , as previously thought , but infinitely many bound states . this is a simple consequence of the effective attractive @xmath101 potential in eq . ( [ eq : hyperradialequation ] ) . indeed , although the boundary condition eq . ( [ eq : f0bis ] ) breaks the scale invariance of the system under arbitrary scale transformations , one can easily check that eq . ( [ eq : f0bis ] ) is still invariant under a discrete set of scale transformations @xmath129 , with scaling factors that are integral powers of @xmath130 . thus , if the boundary condition gives a solution at some energy @xmath105 , it also gives solutions with energies @xmath131 . there is therefore an infinite number of bound states , forming a geometric series of energies accumulating at zero energy , with scaling factor @xmath132 . this situation is referred to as the _ discrete scale invariance_. remarkably , vitaly efimov has shown that this discrete scale invariance not only holds at unitarity ( @xmath28 ) but also at finite scattering length @xmath26 , when one considers the spectrum in the polar coordinates ( @xmath133 ) of the inverse scattering length @xmath134 and the wave number @xmath119 : @xmath135 the spectrum along a line at a fixed angle @xmath136 has the discrete scale invariance with the scaling factor @xmath130 . this property can be checked by scaling @xmath17 , @xmath134 , and @xmath137 by @xmath138 in eqs . ( [ eq : hypersphericalequation]-[eq : hypersphericalcondition ] ) . as a result , all the three - body bound states show the same trajectory in the @xmath139 plane up to a scale transformation , as shown in fig . [ fig : efimovplot ] . the infinite series of bound - states energies @xmath140 can therefore be described by the discrete scaling of a single universal function @xmath141 through the formula @xmath142 where @xmath88 is an integer labelling the states , and @xmath126 is the binding wave number at unitarity of the state @xmath97 . the value of @xmath126 is set by the three - body boundary condition , so that it may be regarded as a representation of the three - body parameter . a change in the value of @xmath126 simply scales the curves in fig . [ fig : efimovplot ] inwards or outwards from the accumulation point ( @xmath143 , @xmath144 ) . the universal function @xmath145 has been determined numerically and approximated by analytical expressions in ref . this numerical approximation has inaccuracies on the order of 3% for @xmath136 close to @xmath146 , and we give here an improved version : @xmath147\\ \qquad\quad+1.26z^{3}-0.37z^{4}\\ 2.11y+1.96y^{2}+1.38y^{3 } & \mbox{for } \xi\in[-\frac{5}{8}\pi,-\frac{3}{8}\pi]\\ 6.027 - 9.64x+3.14x^{2 } & \mbox{for } \xi\in[-\frac{3}{8}\pi,-\frac{\pi}{4 } ] \end{cases}\label{eq : analyticapproximation}\ ] ] where @xmath148 , @xmath149 , and @xmath150 . the discrete scale invariance not only holds for the three - body bound states , but for the whole three - body spectrum including the scattering continua @xcite . in the three - body scattering continuum for @xmath151 , resonances that arise at threshold from the three - body bound states and persist up to energies @xmath152 also exhibit a discrete - scale - invariant pattern with the scaling factor @xmath138 @xcite . these efimov resonances have been used to evidence efimov states in experiments with ultra - cold atoms , as discussed in section [ subsec : ultracold - atoms ] . on the other hand , for @xmath153 , the disappearance of the three - body bound states below the particle - dimer threshold does not lead to trimer resonances but trimer virtual states , similarly to the disappearance of the two - body bound state below the two - body threshold . the efimov effect has been confirmed by many calculations using finite - range interactions @xcite . in particular , a series of trimer states is obtained in these calculations . one important aspect of systems with finite - range interactions is that the discrete scale invariance is necessarily broken below some distance comparable with the range of interactions . as a result , the spectrum is bounded from below , as it should be physically : the series of trimer states starts from a ground state . finite - range calculations show that in the universal window where the scattering length @xmath26 is much larger than the range @xmath10 of interactions , and the wave number @xmath17 associated with the three - body energy @xmath154 is much smaller than the inverse range @xmath155 , the dimer and trimers follow closely the zero - range theory predictions , in particular the energy spectrum follows the discrete scale - invariant efimov spectrum given by eq . ( [ eq : universalformula ] ) . outside this window , however , the spectrum deviates from the universal predictions of the zero - range theory . typically , the ground - state trimer shows marked deviations from the universal spectrum and does not meet the particle - dimer threshold , which can be understood from a variational argument @xcite . the first excited state may also show some deviations near the particle - dimer threshold , which it approaches closely , following the efimov scenario , but does not necessarily meet @xcite . these features are summarised in fig . [ fig : efimovplotfiniterange ] for a three - body system whose two - body attractive potential @xmath156 is gradually scaled by a strength factor @xmath157 , enabling to change the scattering length and make it resonant for certain values of @xmath157 . [ [ finite - range - corrections ] ] finite - range corrections + + + + + + + + + + + + + + + + + + + + + + + + experimental observations often lie on the border of the universal window , where the zero - range theory may not be accurate enough . some efforts have therefore been devoted to understanding the finite - range corrections to the zero - range theory . a first line of approach is based on the effective range theory @xcite . at the two - body level , deviations from the zero - range theory involve the _ effective range _ @xmath158 , which appears in the low - energy expansion of the @xmath4-wave phase shift @xcite : @xmath159 the effective range @xmath158 is typically , but not always , on the order of the range @xmath10 of the interactions . it is relatively straightforward to take into account this two - body range correction into the three - body problem . in the three - body schrdinger formalism , one can apply a generalised bethe - peierls boundary condition that replaces the scattering length by the energy - dependent quantity @xmath160 . this quantity also appears explicitly in the integrated schrdinger equation of the zero - range three - body problem , known as the skorniakov- ter - martirosian equation @xcite . one can therefore use the low - energy expression of the phase shift given by eq . ( [ eq : lowenergyphaseshift ] ) into these formalisms @xcite . this brings out a correction @xmath161 to the efimov attraction eq . ( [ eq : efimovattraction ] ) @xcite . one can use more elaborate expressions describing the energy dependence of the phase shift over a wider range of energy @xcite . it would be tempting to think that such a procedure regularises the thomas collapse problem of the zero - range theory and sets the three - body parameter through the new length scale given by @xmath158 @xcite . it is indeed the case for a large and negative effective range , a situation that arises in the case of narrow feshbach resonances @xcite - see section [ subsec : narrow - feshbach - resonances ] . however , in general the procedure does not regularise the equations , and one still has to impose a regularisation of the equations that introduces a three - body parameter . such an approach with a fixed three - body parameter has not been quite successful in reproducing experimental data and theoretical calculations with finite - range interactions ; an energy dependence of the three - body parameter is needed to reproduce these results @xcite . a likely reason is that eq . ( [ eq : lowenergyphaseshift ] ) only accounts for the range corrections of the phase shift , i.e. the on - the - energy - shell scattering properties , which correspond to asymptotic properties of two - body systems , but not the off - the - energy - shell properties which correspond to their short - range correlations . in this respect , separable potentials @xcite are useful tools to account for finite - range effects , since they can reproduce both on- and off - the - energy - shell finite - range effetcs , while keeping the simplicity of the zero - range theory @xcite - see appendix for details . an alternative and more systematic approach to range corrections is based on the effective field theory @xcite . effective field theory @xcite is the effective theory that one can write at low energy respecting the basic symmetries of the systems . in this framework , the ratio @xmath162 of the range of interaction over the scattering length can be treated as an expansion parameter . the leading order in this expansion reproduces the zero - range theory @xcite . calculations to the next - to - leading order have been performed in refs . @xcite and show the necessity to introduce a second three - body parameter to renormalise the equation at this order . a more recent approach @xcite based on numerical calculations with model potentials has provided an empirical way to reproduce range corrections to the zero - range theory . these works show that finite - range deviations from universal formulas such as eq . ( [ eq : universalformula ] ) can be accounted for to a good accuracy over a wide range of scattering length and energy by simply replacing the scattering length @xmath26 by a length @xmath163 , and shifting the three - body parameter by a quantity inversely proportional to @xmath26 . the length @xmath163 is defined as the value @xmath164 that is the solution of @xmath165 , corresponding to the pole of the scattering amplitude @xmath166 , provided that an analytic continuation to imaginary @xmath17 is possible . for @xmath153 , the energy @xmath167 therefore coincides with the two - body bound - state energy , while for @xmath151 it corresponds to the energy of a virtual bound state , since there is no physical bound state . this procedure has been used to fit theoretical results obtained with finite - range interactions , as well as experimental data obtained for lithium-7 @xcite . according to this procedure , the universal formula eq . ( [ eq : universalformula ] ) for the trimer energy is modified as follows ( changes are emphasised in red ) , @xmath168 equivalently , the finite - range energy curve can be mapped to the original efimov curve by plotting the renormalised energy @xmath169 ( or wave number @xmath170 ) as a function of the renormalised inverse scattering length @xmath171 with the @xmath26-dependent renormalisation coefficient @xmath172 . an example of such mapping will be shown in the case of helium-4 in section [ subsec : helium-4 ] . the replacement @xmath173 is related to the two - body range correction given by eq . ( [ eq : lowenergyphaseshift ] ) . indeed , according to the definition of @xmath163 and to eq . ( [ eq : lowenergyphaseshift ] ) , one has : @xmath174 in contrast , the shift @xmath175 is a range correction to the three - body parameter , @xmath176 that is likely associated with two- and three - body short - range correlations . the form of this shift was recently justified from effective - field theory @xcite , but the value of @xmath177 has so far been determined only numerically for each value of @xmath88 to reproduce finite - range calculations . these results suggest that , with the introduction of the parameters @xmath158 and @xmath177 characterising fnite - range corrections , the universality of efimov physics may be extended beyond the window of validity of the zero - range theory . electrically charged particles are subjected to the coulomb interaction . it is a long - range interaction , whose potential decays as @xmath178 , thus more slowly than @xmath2 . for such interactions , there is no range beyond which the particles effectively cease to interact . therefore , there is no efimov physics associated with coulomb interactions themselves . however , particles interacting with short - range interactions may also interact with additional coulomb interactions due to their electric charge . such is the case of protons or nuclei , which interact through the short - range nuclear forces as well as the repulsive coulomb interaction . if the short - range interactions are resonant , there is an expected interplay between the @xmath101 efimov attraction eq . ( [ eq : efimovattraction ] ) and coulomb forces . to our knowledge , this interplay has not been studied explicitly , due to the technical difficulties in solving the three - body problem with coulomb interactions @xcite . nevertheless , some simple considerations can be made , as discussed by vitaly efimov in his original paper @xcite . since the coulomb potential decays as @xmath178 and the efimov attraction decays as @xmath101 , the latter dominates at short distances and the former dominates at large distances , breaking the scaling invariance . the distance where this transition occurs is given by the bohr radius @xmath179 where @xmath9 is the mass of particles , @xmath180 is their electric charge , and @xmath181 is coulomb s constant . on the other hand , the efimov attraction exists only beyond the range @xmath10 of the short - range resonant interaction . therefore , the window of existence for the efimov attraction is delimited by the range @xmath10 of the short - range forces and the bohr radius @xmath182 . within this window , efimov states can be bound by the efimov attraction , and their number scales as @xmath183 . a necessary condition for the existence of efimov states in these systems is thus @xmath184 the single - particle problem in a sum of @xmath185 and @xmath178 potentials was treated quantitavely in ref . @xcite , and corroborates these qualitative considerations . even if particles are electrically neutral , they may possess an electric or magnetic dipole moment that creates a dipole - dipole interaction between them . in the ultra - cold atom research community , there has been a growing interest in studying particles interacting via dipole - dipole interactions . prime examples are atoms with a large magnetic dipole moment @xmath186 , such as @xmath187cr ( @xmath188 , where @xmath189 is the bohr magneton ) @xcite , @xmath190dy ( @xmath191 ) @xcite , and @xmath192er ( @xmath193 ) @xcite . systems with dipolar interactions can also be realised with polar molecules that possesses a permanent electric dipole moment @xmath194 @xcite . for these atoms and molecules , the strength and the polarisation direction of the dipole interaction can be controlled by external magnetic or electric fields , aligning the dipoles in certain directions . for two particles with dipole moments induced by an external field and aligned along the vertical direction , the dipole - dipole interaction potential at large distance has the form @xmath195 where @xmath194 is the dipole moment ( expressed in units of @xmath196 ) , @xmath3 is the distance , and @xmath197 is the polar angle between the two particles . it is thus an anisotropic interaction with a long - range tail . while it is seemingly more complicated than isotropic short - range interactions discussed in sections [ subsec : efimov - theory ] and [ subsec : finite - range - interactions ] , the two - body physics of dipoles turns out to exhibit the same universal behaviour as that of short - range interactions around the threshold regime at which two dipoles are about to form an @xmath4-wave dominated bound state @xcite . close to such @xmath4-wave dominated resonances , the coupling between different partial waves induced by the dipole interaction occurs at a distance much smaller than the spatial extent of the bound state since the coupling decays as @xmath198 . one can therefore essentially consider a single channel scattering in the @xmath4-wave channel , in which the dipole interaction averages out to zero and one is left with a short - range interaction in this channel . the calculation of this interaction in second - order perturbation theory ( through the coupling of the @xmath4 wave to the @xmath194 wave ) shows that it decays as @xmath199 with @xmath200 and @xmath201 @xcite is derived from eq . ( 34 ) in ref . @xcite , as we could not reproduce the value @xmath202 given after eq . ( 34 ) of the same reference . ] , where @xmath203 is the dipole length defined as @xmath204 because of this similarity of the dipole - dipole interaction with a @xmath205 short - range attraction in the @xmath4 channel , the two- and three - body physics near an @xmath4-wave dominated two - body resonance shows the same universal behaviour as that of short - range interactions . namely , near an @xmath4-wave dominated resonance , the dimer energy scales with the scattering length according to the universal formula eq . ( [ eq : universaldimerenergy ] ) @xcite , and the efimov effect occurs @xcite . in ref . @xcite , yujun wang and co - workers have considered the three - body problem of identical bosons with the dipole - dipole interaction in the proximity of the @xmath4-wave dominated resonance . they have found the appearance of efimov states with the same universal scaling factor @xmath206 as that of systems with short - range interactions . one notable feature of the dipolar efimov states is that their three - body parameter is universally set by the dipole length , @xmath207 in the absence of other forces at distances comparable with the dipole length . the insensitivity of the three - body parameter to forces at shorter distances than the dipole length is due to the strong repulsion created by the partial wave couplings induced by the dipole interaction . this repulsion appears at a distance on the order of the dipole length . it prevents the three dipoles from getting closer than the dipole length and renders the three - body parameter universal . as we shall see in sections [ subsec : van - der - waals - universality ] and [ subsec : other - types - of - interactions ] , a three - body repulsion also appears in systems with isotropic short - range interactions , in particular power - law decaying interactions , and makes in some limit the three - body parameter universally determined by the effective range . it would be therefore tempting to think that the three - body universality of the dipole -dipole interaction is related to the three - body universality of its effective @xmath205 interaction in the @xmath4 wave channel . however , the universal three - body parameter for such an @xmath205 interaction has been estimated to @xmath208 @xcite , which is almost a factor of three different from the value in eq . ( [ eq : dipolethreebodyparameter ] ) . this indicates that the dipole - dipole interaction belongs to a different class of three - body universality that involves the explicit partial wave coupling at short distance . we will discuss the universality classes of the three - body parameter for isotropic short - range interactions in more detail in section [ subsec : other - types - of - interactions ] . the dipolar three - body physics leads to an even more interesting behaviour when the particles are identical fermions . while identical fermions do not exhibit efimov physics ( see section [ sec : three - identical - fermions ] ) , yujun wang and co - workers have found in ref . @xcite that there exists a new type of three - body bound state , which is universally described by the dipole interaction . the size of this bound state is of the order of the dipole length , and it has a shape of an obtuse isosceles triangle , whose longer side is parallel to the polarisation axis of the dipoles . this particular shape originates from a competition between the dipole interaction and the pauli exclusion principle , maximising the attraction between the dipoles by aligning them in parallel while preserving the antisymmetrisation condition by having nodes between them . the efimov effect , seen as the infinite accumulation of three - body bound states with smaller and smaller binding energies in the three - body spectrum , is by definition a low - energy phenomenon . it is thus not directly affected by relativity . nevertheless , if the range of interactions between particles is smaller than their compton wave length , relativistic corrections may affect the most deeply bound efimov states and the three - body parameter . in particular , when the range of interactions is so small that they can be approximated by contact interactions , there is still a length scale in the relativistic theory , the compton wave length , that may prevent the thomas collapse and set the three - body parameter , instead of the interaction itself . the first authors to look at the efimov effect in a relativistic framework were james v. lindesay and h. pierre noyer in the 1980s @xcite . they considered three bosons of rest mass @xmath209 , interacting with attractive contact interactions such that the total energy @xmath210 of two particles may be less than @xmath211 . they obtained the following integral equation instead of @xmath212 . in the first paper @xcite , the numerical calculations were performed with this wrong factor and are therefore incorrect for identical bosons . ] for the three - body energy @xmath213 : @xmath214 where @xmath215 , @xmath216 , @xmath217 , and the scattering length @xmath26 is given by @xmath218 where @xmath219 is the sign of @xmath220 . for @xmath221 and @xmath222 , one retrieves the non - relativistic integral equation . however , unlike the nonrelativistic equation , the integral above has a finite upper limit of integration , which comes from the relativistic kinematics . this prevents the thomas collapse and the three - body energy is set by the rest mass @xmath209 ( or equivalently the compton wavelength @xmath223 ) . from this equation , the authors concluded that the efimov scenario is qualitatively unchanged . the ground - state trimer appears for @xmath224 and its energy at unitarity ( @xmath225 ) is @xmath226 , i.e. it is bound by an energy @xmath227 with respect to the three - body threshold @xmath228 . it disappears below the particle - dimer threshold at @xmath229 . the first excited trimer is bound by @xmath230 at unitarity , which is about a factor 507 from the ground state , relatively close to the non - relativistic scaling ratio @xmath231 for excited states . the same problem was independently addressed a few years later by tobias frederico @xcite in the light - front dynamics formalism @xcite . the author derived the following integral equation , @xmath232 where @xmath233 with @xmath234 and @xmath235 , and @xmath236 . here , the integral boundaries are set to @xmath237 and @xmath238 . like eq . ( [ eq : lindesay - noyer ] ) , this equation also reduces to the non - relativistic integral equation in the non - relativistic limit . solving this equation , the author reached conclusions similar to those of refs . @xcite , with relatively different numerical results . in particular , the ground - state trimer is bound by about @xmath239 at unitarity and disappears below the particle - dimer threshold at @xmath240 . in a more recent work using a similar formalism @xcite , jaume carbonell and v. a. karmanov argued that for zero - range interactions the boundaries of the integrals assumed in the previous work @xcite should be changed to @xmath241 and @xmath242 . this results in a drastically smaller binding energy at unitariy @xmath243 for the ground state , which is remarkably close to the results of lindesay and pierre noyer in ref . in addition , the ground - state trimer does not disappear below the particle - dimer threshold . instead , its energy vanishes at @xmath244 , which the authors called the `` relativistic thomas collapse '' . for a smaller mass @xmath210 than this critical value ( i.e. a stronger two - body attraction ) , the three - body energy @xmath213 is formally imaginary , making it unphysical . the results of these works are summarised in fig . [ fig : relativistic ] . before we address the observations of efimov states , we have to ask ourselves what is an efimov state , and what constitutes an experimental evidence of such a state . the answer to these questions varies somewhat from one person to the other . the major issue is whether the ground - state trimer , which is the most likely to exist and most easily observable , should be included or not in the series of efimov states . let us review some proposed definitions of efimov states based on their energy spectrum . 1 . in the strictest sense , efimov states are evidence of the efimov effect , i.e. an accumulation point in the three - body spectrum at zero energy as shown in fig . [ fig : efimovplot ] . in this sense , one can not evidence a single efimov state , one needs to exhibit several ( at least two ) of these states and show that they follow the predicted discrete scale invariant pattern . in this definition , the observation of the ground - state trimer is not an evidence of an efimov state . 2 . in another definition , one may allow a single state to qualify as an efimov state , if it can be shown that its variation with scattering length follows qualitatively the universal curve obtained in the zero - range theory and shown in fig . [ fig : efimovplot ] , sometimes referred to as the `` efimov scenario '' . namely , the trimer has to appear from the three - body threshold at some negative scattering length , and disappear in ( or approach closely ) the particle+dimer threshold at some positive scattering length . the ground - state trimer often remains far below the particle+dimer threshold @xcite , and thus does not qualify as an efimov state in this definition @xcite . 3 . in their review article @xcite , eric braaten and hans - werner hammer advocated a broader definition : `` a trimer is defined to be an efimov state if a deformation that tunes the scattering length to @xmath245 moves its binding energy along the universal curve '' . in this definition , the trimer does not have to meet the particle+dimer threshold on the positive scattering length side . the ground state trimer is therefore usually an efimov state according to this definition . 4 . the results of refs . @xcite suggest a somewhat related definition : a trimer is defined to be an efimov state if the trimer energy as a function of @xmath163 can be fitted by the modified universal formula eq . ( [ eq : modifieduniversalformula ] ) . the authors of refs . @xcite have presented numerical evidence that close to unitarity the ground state is expected to be an efimov state in this definition . the first two definitions are qualitative : a given state is either an efimov state or not . the last two definitions are less restrictive and can be made quantitative : by comparing the energy with the universal or modified universal formulas , one may quantify how much of an efimov state a given trimer is . the disadvantage of definitions 2 , 3 , and 4 is that they require the variation of the two - body scattering length , which is not always possible experimentally if the interactions can not be controlled but are just set by nature . from a physical point of view , it would be natural to say that a trimer is an efimov state if the efimov attraction is present and necessary to ensure its binding , although this point is difficult to characterise experimentally , and even theoretically for real systems . we should mention that the notion of efimov trimer is not restricted to bound states and can be extended to resonant states . when the two - body interaction potential supports several two - body bound states and one of them has zero angular momentum and is very close to threshold , it leads to a situation similar to what the efimov theory predicts for just one two - body bound state , except that the efimov trimers are resonant states that can dissociate into a particle and a deeper two - body bound state . such resonant states are shown as dotted curves in fig . [ fig : efimovplotfiniterange ] . as long as this dissociation is weak , the trimer resnonances are narrow and follow the efimov scenario . they can therefore be qualified as efimov states . in fact , it is the situation encountered in ultra - cold atomic gases - see section [ subsec : ultracold - atoms ] . for very strong losses by dissociation , the trimer resonances are broad and a theoretical study indicates that the efimov spectrum is rotated in the complex energy plane @xcite , where the imaginary part of the energy correspond to the resonance width . although the peculiar energy spectrum of efimov states is often presented as their defining characteristic , their spatial structure is also worth considering , as it makes them very different from other three - body bound states such as water or ozone molecules . ozone molecules , for instance , have a relatively well defined geometry , with an o - o length of about 0.127 nm and an o - o - o angle of about 117 . although the electrons are delocalised around the oxygen nuclei , the relative positions of the nuclei are quite localised , as a result of the strong binding interaction provided by the bonding electrons . efimov states , on the other hand , are very diffuse objects without a well defined geometry . in the intuitive picture of the efimov attraction , the particles keep moving back and forth between one another , thereby inducing the efimov attraction that keeps them together . thus , for an efimov state made of atoms , one may say that the atoms themselves play the role of bonding electrons by performing an exchange motion . the electrons play a role only when the atoms come in contact , within the radius of their electronic cloud , which is on the order of a few tenths of nanometre for light atoms . the motion of the atoms , on the other hand , occurs at distances larger than the size of their electronic cloud , around three times for the ground state and much more for excited states . as result , efimov states of atoms are much larger and diffuse than usual molecules . this is shown in fig . [ fig : molecules ] for the case of helium-4 trimers , whose excited state is typically fifty times or more larger than ozone molecules . in addition to the broad distribution of sizes , there is also a broad distribution of geometries for three particles forming an efimov state . the most probable geometries in this distribution correspond to elongated triangles , where two particles are relatively close and the third one is farther away . this can be checked at unitarity from the hyper - angular wave function in eq . ( [ eq : hyperangularsolution ] ) , which peaks at @xmath78 , corresponding to two particles in contact with the third particle away . for the full wave function of eq . ( [ eq : faddeevdecomposition ] ) , one obtains the average value of @xmath74 to be close to @xmath246 , corresponding to an elongated triangle . these distinctive structural properties can be used to experimentally characterise a trimer as an efimov state , when structural properties can be measured . this was recently demonstrated in the coulomb explosion imaging of helium-4 trimers @xcite - see section [ subsec : helium-4 ] . this experiment revealed that the distribution of geometries for the excited trimer state of helium-4 conforms to the distribution of an efimov state favouring elongated triangles , whereas the distribution for the ground state is broader and does not seem to favour any particular geometry . this is due to the fact that finite - range effects are more important for the ground state and tend to push the system to a more equilateral configuration ( see a discussion of this effect in section [ par : connection - with - two - body - physics ] ) . for this reason , ground - state efimov trimers are in general not expected to exhibit the distribution of geometries of an ideal efimov state . nevertheless , the absence of a well - defined geometry make even the ground - state efimov trimers very distinct from conventional molecules , as fig . [ fig : molecules ] illustrates . bosonic particles in nuclear physics are compounds of fermions . in the case of nucleons , since neutrons do not bind , bosonic clusters have to involve protons . this introduces coulomb interactions which do not qualify as short - range interactions . nevertheless , as discussed in section [ subsec : coulomb - interactions ] , efimov physics can survive in this context : if the short - range nuclear interactions are resonant , they create a three - body efimov attraction that competes with the coulomb repulsion to form bound states . although these states do not necessary follow the definitions of efimov states put forward in section [ subsec : efimovenergy ] , they could still be regarded as efimov states in the sense of being bound by the efimov attraction . a necessary condition for the efimov attraction to survive is given by eq . ( [ eq : conditionforefimovincoulombsystems ] ) . this condition can only be satisfied by light nuclei . the hoyle state is an excited resonant state of carbon-12 predicted by fred hoyle in 1954 . it plays a crucial role in the stellar nucleosynthesis of carbon . in his original papers @xcite , vitaly efimov suggested that the hoyle state may be viewed as a trimer of alpha particles ( i.e. helium nuclei , which are bosons ) bound by the efimov attraction . the works of renato higa and hans - werner hammer @xcite based on effective - field theory looks into the effect of the coulomb interactions on alpha systems close to unitarity . they conjectured that the hoyle state is indeed a remnant of the efimov spectrum broken by the coulomb interaction , surviving as a resonance above the three - alpha scattering threshold . the corresponding picture of the hoyle state would be a resonant state resulting from the balance between the efimov attraction and the coulomb repulsion . this picture is shown in fig . [ fig : hoyleefimov ] . although this picture of the hoyle state is quite appealing , there are two points that make it questionable . first , excluding the coulomb repulsion , the nuclear force between two alpha particles does not seem to be resonant , as the scattering length of the model potentials @xcite for the alpha - alpha interaction is about 5 fm , which is similar to the range @xmath10 and effective range @xmath247 fm of these potentials . the resonance condition eq . ( [ eq : resonancecondition ] ) may therefore not be satisfied . this would suggest that the attraction between alpha particles is directly due to the nuclear force rather than the efimov attraction . second , even if the alpha - alpha interaction is resonant , the efimov attraction seems too weak to overcome the coulomb repulsion and support a resonant state at distances larger than the range @xmath10 . indeed , the value of the bohr radius given by eq . ( [ eq : bohrradius ] ) for alpha particles is @xmath248 fm . the condition @xmath249 of eq . ( [ eq : conditionforefimovincoulombsystems ] ) therefore does not appear to be satisfied . these conclusions rely on rough estimates , and only a full treatment of the three - body problem with short - range and coulomb interactions can give a definite answer . the three - body model calculation of the hoyle state by hiroya suno , yasuyuki suzuki , and pierre descouvemont @xcite gives a preliminary answer . in their work , they show the contributions from the coulomb , nuclear and centrifugal ( kinetic ) energies as a function of the hyper - radius . although an attractive well ( presumably due to the efimov attraction ) can be seen in the centrifugal energy , it appears that it is not enough to overcome the coulomb repulsion , and it is the nuclear force that is responsible for the stability of the hoyle state in this model . it is therefore likely that the hoyle state may not be considered as an efimov state . most atomic species have bosonic isotopes , and interactions between neutral atoms is of the short - range type , decaying with a @xmath198 van der waals tail . they therefore appear as ideal systems for the observation of the efimov physics of identical bosons described previously . however , the remaining condition that the interaction be resonant is more difficult to satisfy . in most cases , the scattering length is on the order of the range of the atomic interaction . only in accidental cases does the scattering length happen to be much larger than the range of the interaction . such is the case of helium-4 atoms discussed below . for a long time , helium-4 appeared as the only promising atomic species for observing efimov states . the situation changed drastically with the implementation of magnetic feshbach resonances in ultra - cold atoms experiments @xcite . thanks to these resonances , it has been possible to change at will the scattering length between various species of atoms by simply varying the strength of an applied magnetic field . this has enabled a detailed exploration of efimov physics in these atomic systems . [ [ theoretical - predictions ] ] theoretical predictions + + + + + + + + + + + + + + + + + + + + + + + because of its simplicity , the interaction potential of atomic helium has been widely studied . the range of this potential can be characterised by its van der waals length , which is about 0.54 nm and its scattering length turns out to be about 20 times larger than this range , around 10 nm . this fact makes helium-4 systems close to the resonance condition eq . ( [ eq : resonancecondition ] ) for efimov physics . it was first noted by t. k. lim and co - workers @xcite who suggested that helium-4 atoms may exhibit the first example of efimov trimer in nature , based on approximate three - body calculations . this triggered many subsequent three - body calculations using refined methods and helium potentials @xcite ( see also references in @xcite ) . these calculations predicted the existence of two helium-4 trimers . the one with lowest binding energy ( the excited trimer ) was identified as an efimov trimer , in accordance with the definitions of section [ subsec : what - is - an - efimov - state ] . the ground - state one has not been regarded as an efimov trimer , because its energy does not fit well in the discrete scale - invariant pattern of the efimov universal theory . according to definitions 3 and 4 of section [ subsec : what - is - an - efimov - state ] , however , the ground - state trimer is also an efimov state . to appreciate how the two trimer states of helium-4 fit in the efimov picture , one can change the scattering length between two helium atoms by scaling their interaction potential by some variable factor , and plot the trimer energies as a function of the varied scattering length . this is represented in fig . [ fig : helium1 ] . when the scattering length is tuned to infinity , the efimov effect occurs and an infinite number of trimer states exist . at the physical value of the scattering length , only two trimer states remain , below the atom - dimer threshold . as the scattering length is varied , these two trimer states roughly follow the efimov scenario , although none of them dissociate into the atom - dimer threshold for the helium potential used in fig . [ fig : helium1 ] . as expected , the ground - state trimer shows the most marked deviations . the excited trimer energy comes very close but always remains below the dimer energy , which can not be seen in fig . [ fig : helium1 ] . the significant deviations of the dimer and trimer energies with respect to the ideal efimov spectrum can be accounted for by finite - range corrections . one can for instance replace the zero - range interaction by a separable interaction parameterised to reproduce exactly the scattering length and effective range of the helium potential ( see appendix for details ) . this interaction indeed reproduces the scattering length dependence of the deviations , although the trimer energies are off by a small shift that can be removed by adding a three - body force @xcite . alternatively , one can use the finite - range corrected universal formula eq . ( [ eq : modifieduniversalformula ] ) . this formula allows one to map the helium trimer energies to the ideal efimov spectrum by plotting the renormalised wave number @xmath250 as a function of the renormalised inverse scattering length @xmath251 , where @xmath252 . the resulting plot is shown in fig . [ fig : helium2 ] . [ [ experimental - observations ] ] experimental observations + + + + + + + + + + + + + + + + + + + + + + + + + the first experimental investigation was carried out by the group of jan peter toennies in gttingen @xcite . a beam of helium clusters was generated by cryogenic expansion and diffracted through a nanostructured transmission grating . the mass and spatial extent of diffracted clusters were measured , revealing the existence of the ground - state helium trimer with spatial extent of @xmath253 nm , in agreement with theoretical predictions . the excited trimer was not observed in that experiment__. _ _ both trimers were eventually observed in the group of reinhard drner in frankfurt _ _ _ _ @xcite by coulomb explosion imaging . although the trimer energies have not been measured , the coulomb explosion imaging technique enables to measure structural properties of the trimers and to some extent reconstruct their wave functions , in very good agreement with the theoretical calculations . from these observations , the authors concluded that the ground trimer s structural properties are very different from those of an ideal efimov trimer , whereas the excited trimer conforms relatively well to the structure of an efimov trimer . the field of ultra - cold atomic gases has developed from laser - cooling experiments in the 1980s . it consists in magnetically or optically trapping inside a vacuum chamber a cloud of atoms cooled to ultra - low temperatures , from microkelvins down to a few nanokelvins . in this setting , it was realised that the scattering length between the atoms could be changed through a feshbach resonance by applying a magnetic field to the cloud @xcite . a feshbach resonance @xcite is a general resonance phenomenon of particles with different possible internal states ( for instance , hyperfine states in the case of atoms ) . the various pair combinations of internal states constitute different two - body scattering channels . these channels are in general coupled at short distance by some interactions ( for example , the hyperfine interaction in the case of atoms ) . if the scattering threshold of some incoming channel ( the `` open '' channel ) is close to the energy level of a two - body bound state in another or several other channels ( the closed channel ) , the coupling between these two channels makes the scattering in the open channel resonant , i.e. the scattering length can become much larger than the range of the interaction potentials in these various channels . if the spacing between the threshold and bound - state energy can be controlled ( for instance by applying a magnetic field and shifting by the zeeman effect the threshold and bound - state energy by different amounts ) , the resonance condition and therefore the scattering length can be tuned . this technique has been extremely successful for controlling interactions in ultra - cold atomic gases , and studying efimov physics in particular . [ [ observation - through - loss ] ] observation through loss atomic efimov trimers arise when the scattering length of the interatomic potentials is tuned to a large value . this corresponds to the presence of an @xmath4-wave two - body bound state or virtual state near the two - body scattering threshold . however , for atoms commonly used in ultra - cold gases , these potentials also support many other two - body bound states that are more deeply bound , i.e. diatomic molecular states of various rotational symmetries . this introduces two complications with respect to the ideal efimov scenario . the first one is that the many diatomic molecular levels experience different zeeman shifts as the magnetic field is varied to tune the scattering length . this can result in a second molecular state reaching the threshold and creating a feshbach resonance overlaping with the resonance of interest , thus complicating the relationship between the magnetic field and the scattering length . this situation is illustrated by the many overlapping feshbach resonances of cesium-133 ground - state atoms @xcite . however , when the two resonances have very different widths , the efimov physics associated with one resonance may not be significantly affected by the presence of the other . a second consequence of the different zeeman shifts of the molecular levels is that there can be many avoided crossings between these levels . sometimes such a crossing may strongly affect the @xmath4-wave two - body bound state associated with the feshbach resonance , resulting in a quick departure from the zero - range picture . this is the case , for instance , for the cesium dimer associated with the feshbach resonance near 800 g , which remains very close to the threshold due to an avoided crossing with a weakly bound molecular level of the open channel @xcite . nevertheless , the efimov effect still occurs close to resonance . the second complication is that efimov trimers are not true bound states , since they have a much smaller binding energy than the many diatomic molecular states . instead , these trimers exist as resonances embedded in the continua formed by the scattering of one atom and one diatomic molecule , as shown by the dotted curves in fig . [ fig : efimovplotfiniterange ] . as a result , these trimers have a finite lifetime as they can decay in these continua by dissociating into an atom and diatomic molecule . this situation is different from that of helium-4 , for which the potential supports only one two - body bound state and efimov trimers are true bound states that are infinitely long lived . nevertheless , the dissociation processes are weak enough to allow to resolve the trimer resonances , which were found to conform to the general efimov scenario . it is for this reason that these resonances are thought to be a good approximation of efimov states , even though they are not true bound states . ultra - cold atom experiments typically start with a gas of unbound atoms , dimers , or atom - dimer mixtures . three - body bound states can be formed through inelastic collisions @xcite but these states are difficult to observe in the standard setups . nevertheless , these collisions tend to deplete the gas of atoms and this loss can be monitored by imaging the gas . this can be used to indirectly observe the three - body bound states through their influence on inelastic collisions . for example , when three atoms collide in an ultra - cold gas , two of them may recombine into a diatomic molecule . the energy gained by this binding is then redistributed as kinetic energy between the formed molecule and third atom . this inelastic process can be strongly enhanced at the low collisional energy of ultra - cold atoms by efimov resonances that occur whenever an efimov trimer lies just below the three - body scattering threshold . as one varies the scattering length through the values @xmath254 shown in fig . [ fig : efimovplot ] , one therefore expects to see peaks in the loss rate . the existence of these peaks were first predicted in 1999 by brett d. esry , chris h. greene , and james p. burke jr in ref . eric braaten and hans - werner hammer subsequently derived from the zero - range theory a simple analytical formula for the three - body recombination loss rate coefficient @xmath255 at zero temperature @xcite : @xmath256+\sinh^{2}\eta}\frac{\hbar a^{4}}{m},\qquad(\mbox{for } a<0)\label{eq : recombinationrate}\ ] ] as a function of the scattering length @xmath26 , the three - body parameter characterised by @xmath254 , and an inelasticity parameter @xmath257 describing the decay to diatomic molecules . @xmath258 is a numerical constant . this formula shows that @xmath255 has a local maximum when the @xmath259 term vanishes , corresponding to scattering lengths that are multiples of @xmath254 with the efimov scaling factor , i.e. @xmath260 . such a peak was seen in the early experiments on feshbach resonances and subsequently interpreted as an efimov resonance . the first observation was made in 2002 and the final results were reported in 2006 @xcite by the group led by hanns - christoph ngerl and rudolf grimm in innsbruck for an ultra - cold gas of cesium-133 atoms in their hyperfine ground state @xmath261 , where @xmath262 and @xmath263 designate the hyperfine quantum numbers . the feshbach resonance used to tune the scattering length in this experiment is a bit particular , because it occurs at a `` negative value of the magnetic field '' @xmath264 g , which physically corresponds to the excited hyperfine state @xmath265 of cesium-133 . this excited state is not stable against two - body decay , so the experiment was limited to the positive values of @xmath266 . although the dimer causing the resonance exists only for @xmath267 g , the resonance makes the scattering length very large and negative for @xmath268 g , making it possible to observe efimov physics . in this range , however , only the ground efimov state exists @xcite , and was revealed by a peak in the measured three - body loss rate . this allowed not only to prove the existence of an efimov trimer , but also measure the value @xmath254 which is related to efimov s three - body parameter . since the ground - state efimov trimer does not completely follow the efimov universal scenario , some objections on the terminology of `` efimov state '' were raised @xcite . indeed , the cesium trimer evidenced in the experiment , when followed to the negative side of magnetic field values where the dimer appears from the two - body threshold , is not expected to approach the atom - dimer threshold , and therefore does not conform to definition 2 given in section [ subsec : what - is - an - efimov - state ] . however , it is expected to be an efimov state according to definition 3 and 4 . moreover , unlike the ground - state trimer of helium-4 , which occurs in the region of positive scattering length where deviations from the efimov scenario are significant , the loss peak observed for cesium corresponds to the region of negative scattering length , where the ground - state trimer is borromean and follows more closely the efimov scenario . for these reasons , this experiment may be thought to constitute the first experimental demonstration of a borromean efimov state . in the following years , many similar observations of efimov resonances were made with various kinds of atomic species . for positive scattering lengths , the trimer energy is below the dimer energy . at some value @xmath269 of the scattering length , the trimer energy can reach , or approach closely , the atom - dimer threshold , creating a low - energy resonance in atom - dimer scattering , which can be seen as a peak in the rate of losses associated with inelastic atom - dimer scattering . efimov physics can also be seen in the three - body inelastic scattering for positive scattering length . in this case , recombination to dimers can take two paths , and as a result of quantum interference between the two paths , a minimum in the three - body recombination loss rate is expected for a value @xmath270 of the scattering length . the zero - range theory for these efimov features in the loss measurement at zero temperature were done in several theoretical contributions @xcite ( see references in @xcite ) . the influence of temperature has appeared to play an important role for the identification and interpretation of the resonance position , and was treated theoretically in refs . @xcite . studying the inelastic collisions between weakly bound dimers and unbound atoms of cesium-133 @xcite , the innsbruck group observed an atom - dimer resonance as predicted by the efimov scenario and measured the value of @xmath269 of fig . [ fig : efimovplot ] . the group of giovanni modugno and massimo inguscio in florence @xcite observed both a local maximum and local minima in the three - body recombination rate of potassium-39 , thus determining the values of @xmath254 and @xmath270 , as well as inferring the atom - dimer resonance position @xmath269 from a small peak of the three - body loss rate appearing on the positive scattering length side . a similar experiment was performed for lithium-7 atoms by the group of randall g. hulet at rice university @xcite . from these experiments , the following measured ratios were reported : @xmath271,\ -2.5\pm0.2\;[^{7}\text{li}]$ ] and @xmath272,10.4\pm1.5\;[^{7}\text{li}]$ ] . these results were later modified in 2013 in refs . @xcite and @xcite due to a misassignment of the three - body loss peak , which were interpreted as signatures of an efimov trimer ( @xmath273 ) and an associated tetramer . later however , the same group could not find the peak at @xmath274 @xcite , and reassigned the other peak to a trimer , with the updated value @xmath275 . ] and to a recalibration of the feshbach resonance parameters , respectively . the updated values @xmath276,\ -2.8\pm0.3\;[^{7}\text{li}]$ ] and @xmath277 $ ] are in fair agreement with the values predicted by the universal efimov theory @xmath278 and @xmath279 @xcite . the group of lev khaykovich @xcite performed a similar experiment using lithium-7 atoms , and measured @xmath254 and @xmath269 . the ratio @xmath280 obtained in the experiment agrees with the theoretical value above if @xmath254 and @xmath269 are interpreted as corresponding to the ground and first - excited efimov trimers and the universal scaling factor 22.7 is multiplied . the groups from florence @xcite and rice university @xcite have both reported the observation of two dips in the loss rate for positive scattering lengths , i.e. two values of @xmath270 corresponding to a ground - state and an excited efimov trimers . they found the ratio between these two values to be 25(4 ) and 22.5(3 ) respectively , roughly confirming the discrete scale invariance of efimov trimers with the universal ratio 22.7 . the universal scaling was reported to be observed for negative scattering lengths as well in ref . @xcite , although a subsequent recalibration of the scattering length with respect to the magnetic field dismissed the second value of _ @xmath254 _ and corrected the values of @xmath270 , giving a updated ratio 16(2 ) @xcite . more recently , the second efimov trimer could be observed for negative scattering lengths with cesium-133 atoms near a 800 g feshbash resonance @xcite , as originally proposed in ref . the scaling factor between the ground state efimov trimer and second efimov trimer was found to be 21.0(1.3 ) , close to the universal ratio 22.7 . the experimental data for the two efimov resonances are shown in fig . [ fig : cesium ] . this is so far the most convincing experimental evidence of efimov states of identical bosons , according to definition 1 of section [ subsec : what - is - an - efimov - state ] . efimov resonances in an ultra - cold gas of cesium-133 atoms in their lowest hyperfine state , whose scattering length is varied by applying a magnetic field on the order of 800 gauss ( adapted from ref . the resonances appear as peaks in the three - body recombination rate as a function of scattering length . the experimental data of ref . @xcite is shown with different colours corresponding to different data sets , all taken at a temperature of about 10 nk . the data around the first resonance is fitted by the zero - temperature universal formula eq . ( [ eq : recombinationrate ] ) with @xmath281 nm and @xmath282 . the formula predicts a second resonance at @xmath283 nm . the second resonance was observed at @xmath284 nm , corresponding to a factor @xmath285 indicated by the arrow . the height of the peak is much smaller than the zero - temperature prediction , due to the saturation effect of finite temperature @xcite , indicated by the horizontal dotted line for 10 nk . ] [ [ bound - state - spectroscopy ] ] bound - state spectroscopy before the evidence of efimov states through three - body and two - body losses , the association of three colliding atoms in an efimov trimer was theoretically proposed @xcite . such an association , although different from the original proposal , could be achieved experimentally and allowed the direct spectroscopy of efimov trimers . although the first demonstration was done with three distinguishable atoms ( see section [ subsec : observations - with - atoms - multi - component ] ) , the association of three bosons into an efimov trimer was later achieved with lithium-7 atoms in the group of lev khaykovich @xcite . the experiment consists in driving a transition between three colliding atoms and the underlying efimov trimer state by applying a radio - frequency ( rf ) modulation of the magnetic field . when the frequency of the modulation matches the energy difference between the energy of the colliding atoms and the trimer energy , the three atoms are associated in trimers , resulting in a loss of the atoms from the imaged cloud . the resonance could be seen as a small dip in the number of atoms as the frequency of the modulation is varied , on the shoulder of a broader dip due to the association of two atoms into a dimer . most studies of efimov physics have been done in the fields of nuclear physics and atomic physics , but recently there have been works seeking the possibility of efimov physics in other physical systems . here , we present the current prospects for quantum spin systems @xcite and excitons @xcite . quantum spin systems have constituted an important and active field of research in condensed matter physics for more than 70 years . they have been been used with some success to explain and predict various magnetic phenomena in insulating solids . a quantum spin system is a system of spins fixed on the sites of a lattice , which can interact with each other through an exchange interaction . depending on the geometry of the lattice , spatial dimension , and the sign and the spatial extent of the exchange interaction , quantum spin systems can exhibit various magnetic phases . when the ground state of a quantum spin system shows a non - trivial magnetic phase , such as the ferromagnetic or anti - ferromagnetic phases , the symmetry of the hamiltonian is spontaneously broken . the nambu - goldstone theorem dictates that there must exist gapless low - energy excitations , called magnons , in such broken - symmetry systems . for a ferromagnet system , the magnons have the dispersion relation @xmath286 @xcite . this dispersion is similar to that of a non - relativistic particle in the vacuum . from this similarity between the magnons and the non - relativistic particles , yusuke nishida and co - workers @xcite have sought the possibility of finding efimov states in a ferromagetic quantum spin system . to achieve the resonant - interaction condition eq . ( [ eq : resonancecondition ] ) necessary for the appearance of the efimov states , they considered the heisenberg model in three spatial dimensions with an anisotropic exchange coupling and the single - ion anisotropy . these terms originate from the anisotropy in the lattice and the crystal field effect that are present in real materials described by quantum spin systems . in the presence of these terms , the magnons no longer behave as independent quasi - particles , and start to interact . this interacting problem is greatly simplified from the fact that the number of magnons is a conserved quantity in the anisotropic heisenberg model . it is therefore justified to consider the few - body problem for magnons with a well - defined number of magnons . y. nishida and co - workers have shown by analytically solving the two - body problem of magnons that the magnons can form a bound state when the anisotropies are increased . as a result , the scattering length between the magnons diverges at some critical values of the anisotropies at which the bound state of magnons appears , a necessary condition for the onset of efimov physics . y. nishida and co - workers have solved numerically the three - magnon problem at the resonant point . for different values of the spin quantum number and critical anisotropies , the three - body energy spectrum of magnons is found to be in good agreement with the universal efimov spectrum , and to exhibit a discrete scale invariance with a scaling factor close to 22.7 it is important to note that the following features of the anisotropic heisenberg model are the same as the resonantly interacting non - relativistic particles v. efimov considers in his original argument : ( a ) magnons have a low - energy dispersion @xmath286 , ( b ) the number of magnons is conserved , ( c ) the interaction between magnons is short - ranged . these sufficient conditions seem to be a useful guideline for searching efimov states in other systems . to achieve the efimov states of magnons , one needs a fine tuning of the parameters of the system close to the resonantly interacting regime . in the above case , one needs to increase the anisotropy of the exchange interaction or the single - ion anisotropy term , such that the bound state of two magnons is about to appear . although such a fine tuning is rather challenging , it is known that in an organic crystals , the exchange coupling can be modified by applying an external pressure . this may be one route to realise efimov states in quantum spin systems . once one finds a suitable system , y. nishida and co - workers @xcite have argued that the appearance of efimov states can be tested experimentally from the electron spin resonance signal @xcite . an exciton is a bound state of an electron and a hole which appears in a semiconductor excited by a laser . because it is an association of two fermions , it behaves as a boson . while there has been a long history of exciton studies since its first theoretical prediction @xcite , there has been a revival of interest recently by the realisation of the bose - einstein condensates of the excitons @xcite , which had been one of the holy grails in the research on excitons . recently , a possible signature of efimov physics in an excitonic system has been claimed to be observed @xcite . in ref . @xcite , @xmath5-body bound states of excitons , called poly - excitons , have been observed up to @xmath287 by a photoluminescence measurement in a diamond crystal . the binding energies of these poly - exciton states were measured , and compared with those found in other crystals @xcite . they have been found to agree excellently between different crystals if normalized by the binding energy of an exciton , suggesting that the poly - exciton states behave universally , i.e. , they are independent of the details of the crystal and the energy scale of the system . the binding energies are reminiscent of the series of universal binding energies for the @xmath5-body clusters of resonantly interacting bosons discussed in section [ subsec : universal - clusters ] , although it is not clear whether they are related since the exciton - exciton interaction is typically non - resonant . identical fermions ( i.e. , fermions in the same internal state ) can not interact in the @xmath4-wave channel due to the antisymmetrisation , so that the conventional efimov physics appearing for the @xmath4-wave resonance ( see section [ sec : three - identical - bosons ] ) does not occur for such fermi systems . two identical fermions can only scatter in the odd angular momentum channels , and among them , the most dominant channel at low energy is the @xmath288-wave channel . therefore , the scattering amplitude at low energy is written as @xmath289 where @xmath290 is the @xmath288-wave scattering volume , @xmath291 is the @xmath288-wave inverse effective range . note that , although the notations are similar to those of eq . ( [ eq : lowenergyphaseshift ] ) , @xmath290 is a volume and @xmath291 is the inverse of a length . a natural step is to investigate universal three - body physics of identical fermions in the vicinity of resonant @xmath288-wave interaction , i.e. , when the moduli of @xmath288-wave scattering volume becomes divergently large . although such @xmath288-wave resonances are experimentally challenging because they are much narrower than the @xmath4-wave ones and subject to larger atomic number losses , they have been successfully realised in ultra - cold atom experiments with feshbach resonance @xcite . in this section , we review the recent theoretical progress on the few - fermion physics in the vicinity of a @xmath288-wave resonance in three dimensions ( see [ subsec : resonant - p - wave - interactions ] ) , and two dimensions ( see [ subsec : super - efimov - effect ] ) . in three dimensions , the possibility of efimov trimers has been investigated for three fermions with @xmath288-wave resonance @xcite . if one takes @xmath292 and @xmath293 simultaneously in eq . ( [ eq : p - wave_scat ] ) , the moduli of the scattering amplitude takes its maximum value allowed by the unitary bound and the system becomes scale invariant , similarly to the unitary limit in the @xmath4-wave case : @xmath294 and @xmath295 . in this unitary limit @xmath292 and @xmath293 , macek and sternberg have shown , using a pseudo - potential method , that the efimov effect occurs for the identical fermions for a spin 1/2 system ( i.e. , among three identical fermions , two are in the same internal state , while the other is in another internal state ) @xcite . the same conclusion was obtained in ref . @xcite . however , this unitary limit is unphysical , violating the positivity of probability @xcite . indeed , if one believes the @xmath288-wave form of the scattering amplitude eq . ( [ eq : p - wave_scat ] ) for any @xmath296 , where @xmath113 is a cutoff momentum @xmath297 , then the probability of the bound - state wave function outside the range @xmath10 of the potential exceeds unity , suggesting a negative probability at short distance @xcite . the positivity of the probability thus dictates the inverse range @xmath291 to have a finite negative value , satisfying the wigner bound @xcite . @xmath298 equivalently , the scattering amplitude eq . ( [ eq : p - wave_scat ] ) is valid only for @xmath299 at the @xmath288-wave resonance , with @xmath300 satisfying the wigner bound . in refs . @xcite , spin - polarised three identical fermions around the @xmath288-wave resonance have been studied , keeping the wigner bound . three - body bound states with three - fold rotational degeneracy have been found , one state for each channel in @xmath301 channel @xcite and in @xmath302 channel @xcite . both three - body bound states have larger binding energies than that of the @xmath288-wave dimer around the @xmath288-wave resonance . this suggests that the @xmath288-wave molecular bec phase predicted in the studies of the @xmath288-wave resonant two - component fermi system @xcite is not a genuine ground state , but can be subject to trimer formation instability . the recombination rate to the trimers in a gas of @xmath288-wave dimers has been estimated in refs . @xcite , while the three - body recombination to the @xmath288-wave dimer state in a gas of identical fermions has been studied in refs . the trimer states found here are borromean states @xcite : they have finite binding energies at the @xmath288-wave resonance @xmath292 , and they persist for @xmath303 , where no @xmath288-wave dimer exists . as one moves further away from the resonance towards the negative scattering volume side , the trimers finally dissociate into three fermions at three - body continuum @xmath144 . on the positive scattering volume side , the trimer energy becomes equal to the dimer energy , so that the trimers dissociate into a particle plus a @xmath288-wave dimer . in two dimensions , more exotic few - body states emerge . in ref . @xcite , yusuke nishida and co - workers have found that there exists infinite series of three - body bound states in @xmath304 channels with discrete scale invariance . these states , unlike the efimov states , show a _ double exponential scaling _ of their energies @xmath305.\label{eq : supefimov_descale}\ ] ] for this reason , they have been dubbed super - efimov states . here , @xmath197 is a parameter determined by the short - range part of the interaction ( see the final paragraph of this section for more details ) . the super - efimov states , in addition to a non - super - efimovian @xmath21 ground state , have been found to be borromean @xcite , i.e. , they remain bound even in the absence of a two - body @xmath288-wave dimer . we note that the three fermions problem in two dimensions at the @xmath288-wave resonance was also solved in ref . @xcite before the super - efimov states have been found by yusuke nishida and co - workers in ref . @xcite , and the on - shell @xmath306-matrix at the threshold energy was found to show the same double exponential scaling behavior as eq . ( [ eq : supefimov_descale ] ) . while yusuke nishida and co - workers have found the super - efimov states with the renormalization group analysis , as well as by solving a momentum - space integral equation for a separable potential @xcite , they can also be found by other formalisms @xcite . a rigorous mathematical study based on a spectral analysis has proved the presence of the super - efimov effect @xcite . the super - efimov states can also be demonstrated by the hyper - spherical formalism , but some remarks are in order . in the hyper - spherical formalism , the diagonal adiabatic potential in the super - efimovian channel @xmath304 is found to be ( @xmath307 here has the same notation as eq . ( [ eq : hyperradialequation2 ] ) ) @xcite @xmath308 where @xmath108 is the range of the interaction , and @xmath309 is a parameter dependent on the short - range part of the interaction . if @xmath310 and one can neglect the second term , one arrives at the super - efimov states with a double exponential scaling @xmath311}$ ] , which is slightly different from eq . ( [ eq : supefimov_descale ] ) @xcite . however , @xmath309 turns out to be positive definite @xcite , and the second term is relevant at large @xmath72 . due to the second term , eq . ( [ eq : supefimov_adpot ] ) leads to another different scaling behavior @xmath312 at low energy @xcite . the discrepancy between these results can be ascribed to the non - adiabatic term @xmath313 the diagonal non - adiabatic term in the super - efimovian channel @xmath314 has been found to behave in the leading order as @xcite @xmath315 one can see that the first term cancels the second term in eq . ( [ eq : supefimov_adpot ] ) . in ref . @xcite , chao gao and co - authors have studied this system numerically for various classes of potentials , and the next leading order of @xmath314 has been found to be consistent with @xmath316 . one thus obtains a correct hyper - radial potential in the super - efimovian channel as @xmath317 which reproduces the double exponential scaling of eq . ( [ eq : supefimov_descale ] ) found in ref . @xcite . while the double exponential scaling @xmath318 seems too large to be observed in a realistic system , it can be reduced significantly for mass - imbalanced two - component systems @xcite . it has been found that the super - efimov effect also occurs in a 2 identical fermions + 1 particle system or 2 identical bosons + 1 particle system when the inter - species @xmath288-wave interaction is resonant . the scale factor of the super - efimov states decreases as the inter - species mass ratio is increased towards a 2 heavy + 1 light configuration . for instance , for a mixture of @xmath319li and @xmath320cs atoms , corresponding to the mass ratio 22.1 , it reaches a reasonable value @xmath321 . note that the adiabatic approximation , i.e. , the born - oppenheimer approximation , also fails for the mass - imbalanced system even for large mass ratios @xcite , leading to a similarly wrong energy spectrum as mentioned above @xcite . interestingly , chao gao and co - authors have found that the three - body parameters @xmath322 and @xmath197 are universal for the class of van der waals potentials @xcite , in similarity with the van der waals universality of the three - body parameter found for the efimov states of three identical bosons ( see section [ subsec : van - der - waals - universality ] ) . this similarity is reinforced by the fact that four - body bound states ( @xmath323 channels ) exist and are tied to each super - efimov states , showing the same double exponential scaling , in the same way four - body bound states are associated with the efimov trimers ( see section [ sec : many - identical - bosons ] ) . although the super - efimov trimers have yet to be observed in experiments , it is of interest to investigate the universality of the super - efimov states in the @xmath5-body sector ( @xmath324 ) and understand differences and similarities with the conventional efimov physics for three bosons in three dimension . we also note that a borromean three - body bound state , possibly related to the super - efimov states , has also been found in a two dimensional hubbard model in the @xmath325 channel , which corresponds to a spin - polarised three - fermion system @xcite . it is an interesting avenue to search for super - efimov physics in such condensed - matter systems . systems with different kinds of particles , or particles with different internal states ( either referred to as `` components '' ) exhibit an even richer efimov physics than systems of identical particles . these systems have more parameters : the different kinds of particles may have different masses , quantum statistics , and different interactions between them . this situation introduces a few general facts : * for a given three - particle system , there are three inter - particle interactions . at least two of these interactions should be resonant for the efimov effect to occur . this can be understood simply from the picture of mediated interaction : in order for one particle to mediate an effective long - range interaction between two other particles , it must interact resonantly with these two particles . if it interacts resonantly with only one particle , then the mediation to another particle is not possible . * generally speaking , bosonic particles are favourable to the efimov effect , whereas fermionic particles tend to prevent the efimov effect , since their pauli exclusion may overcome the efimov attraction . * the lighter a particle is , the better it mediates interaction between other particles . thus , mass - imbalanced systems tend to enhance the efimov attraction , and enable the efimov effect in fermionic systems . in the following , we review various situations . the general treatment of three different kinds of particles with different masses and interacting with different scattering lengths was first addressed by amado and noble @xcite and efimov @xcite . here , we consider the simpler case of three different particles with equal masses but different scattering lengths @xmath326 , @xmath327 , @xmath328 . a concrete example of this situation is given by particles of the same kind , polarised in three different internal states - see section [ subsec : polarised - systems ] . the general form of the faddeev decomposition used in eq . ( [ eq : faddeevdecomposition ] ) involves three different faddeev components : @xmath329 following the derivation of section [ subsec : efimov - theory ] , we apply the bethe - peierls condition eq . ( [ eq : bethepeierls ] ) for each pair and obtain : @xmath330 using the expansion @xmath331 where @xmath332 has the form : @xmath333 the conditions can be written in a matrix form @xcite : @xmath334\cdot\left(\!\begin{array}{c } \!f_{n}^{(1)}\!\\ f_{n}^{(2)}\!\\ \!f_{n}^{(3)}\ ! \end{array}\right)=0\label{eq : threedistinguishabletwobodycondition}\ ] ] to obtain a non - trivial solution @xmath335 , the determinant of the matrix should be zero . for three resonantly large scattering lengths @xmath336 and hyper - radius @xmath337 , the terms @xmath338 can be neglected and the determinant becomes : @xmath339 whose second factor admits the same imaginary root @xmath128 as that of eq . ( [ eq : transcendentalequation ] ) for three identical bosons . this could be anticipated from the fact that the form of the wave function eq . ( [ eq : faddeevgeneral ] ) can reduce to the bosonic case eq . ( [ eq : faddeevdecomposition ] ) with @xmath340 , when all scattering lengths are equally large . therefore , the same efimov effect that occurs for three bosons also occurs for three distinguishable particles . in particular , this systems exhibits discrete scaling invariance with the same scaling ratio @xmath341 at unitarity @xmath342 . as in the bosonic case , the discrete scaling invariance persists away from unitarity . however , it requires the simultaneous scaling of all scattering lengths . it may therefore not be apparent if only one or two scattering lengths are scaled . we now consider only two resonantly large scattering length , say @xmath343 , and one non - resonant scattering length @xmath326 on the order of the interaction range @xmath10 . in the region of hyper - radius @xmath344 , the terms @xmath345 , @xmath346 in eq . ( [ eq : threedistinguishabletwobodycondition ] ) can be neglected , whereas the term @xmath347 is large and imposes @xmath348 . we are thus left with the equations for @xmath349 and @xmath350 . the determinant of the corresponding matrix is @xmath351 whose second factor admits an imaginary root @xmath352 . the efimov effect therefore occurs in this case as well , although it is weaker . the corresponding discrete scaling invariance ratio is @xmath353 , implying a very sparse efimov spectrum . finally , if there is only one resonantly large scattering length , say @xmath327 , only @xmath349 contributes in eq . ( [ eq : threedistinguishabletwobodycondition ] ) and one is left with : @xmath354 which admits only real roots @xmath86 . there is therefore no efimov effect in this case . this is consistent with the physical picture that the efimov effect is due to the exchange of a particle resonantly interacting with two other particles , which is not possible if only one pair is resonantly interacting . we now consider the case when two of the three particles are identical , either identical bosons or identical fermions . here , `` identical particles '' means that they are in the same internal states ( for a treatment of identical particles with different internal states , see section [ subsec : particles - with - spin ] ) . the mass @xmath209 of these two particles is in general different from the mass @xmath9 of the third particle . the two identical particles are located at @xmath45 and @xmath46 and the light particle at @xmath44 . the three sets of jacobi coordinates for this system read : @xmath355 for @xmath356 , and @xmath357 where the angles @xmath358 $ ] and @xmath359 $ ] are defined by : @xmath360 the three sets are shown in fig . [ fig : jacobi2 + 1 ] . they all satisfy @xmath361 , where @xmath72 is the hyper - radius , and they are related to each other by the following rotation transformations : @xmath362 @xmath363 using the general faddeev decomposition eq . ( [ eq : faddeevgeneral ] ) , and taking into account the symmetry or antisymmetry of the wave function under the exchange of the identical particles 2 and 3 , one obtains the following form of the wave function : @xmath364 the sign @xmath219 corresponds to a plus sign in the case of identical bosons , and to a minus sign in the case of identical fermions . following the derivation of section [ subsec : efimov - theory ] , we apply the bethe - peierls boundary condition eq . ( [ eq : bethepeierls ] ) for pair 12 and 32 , and obtain : @xmath365_{r\to0}\pm2\frac{\chi_{0}^{(2)}(\cos\gamma\vec{\rho},-\sin\gamma\vec{\rho})}{\sin2\gamma\rho}+2\frac{\chi_{0}^{(1)}(-\cos\gamma^{\prime}\vec{\rho},-\sin\gamma^{\prime}\vec{\rho})}{\sin2\gamma^{\prime}\rho}=0\label{eq : bethepeierls2 + 1}\ ] ] @xmath366_{r\to0}+2\frac{\chi_{0}^{(2)}(-\cos\gamma^{\prime}\vec{\rho},-\sin\gamma^{\prime}\vec{\rho})}{\sin2\gamma^{\prime}\rho}\pm2\frac{\chi_{0}^{(2)}(-\cos\gamma^{\prime}\vec{\rho},-\sin\gamma^{\prime}\vec{\rho})}{\sin2\gamma^{\prime}\rho}=0\ ] ] where @xmath367 . the faddeev components can be expressed as a function of the hyper - spherical coordinates , @xmath368 @xmath369 and the orientations @xmath370 and @xmath371 of @xmath372 and @xmath373 . since the particles interact in the @xmath4 wave , we consider the case when @xmath374 is independent of the orientation @xmath370 . in these new coordinates , the bethe - peierls boundary conditions eq . ( [ eq : bethepeierls2 + 1 ] ) become : @xmath375_{\alpha\to0}\pm2\frac{\chi_{0}^{(2)}(r,\frac{\pi}{2}-\gamma,-\hat{\rho})}{\sin2\gamma}+2\frac{\chi_{0}^{(1)}(r,\frac{\pi}{2}-\gamma^{\prime},-\hat{\rho})}{\sin2\gamma^{\prime}}=0\ ] ] @xmath376_{\alpha\to0}+2\frac{\chi_{0}^{(2)}(r,\frac{\pi}{2}-\gamma^{\prime},-\hat{\rho})}{\sin2\gamma^{\prime}}\pm2\frac{\chi^{(2)}(r,\frac{\pi}{2}-\gamma^{\prime},-\hat{\rho})}{\sin2\gamma^{\prime}}=0\label{eq : betherpeierls2 + 1b}\ ] ] one can then expand @xmath374 as follows : @xmath377 where @xmath378 are the spherical harmonics , and @xmath379 are the solutions of the eigenvector equation : @xmath380 with the boundary conditions @xmath381 and the bethe - peierls boundary conditions from eq . ( [ eq : betherpeierls2 + 1b ] ) . the eigenvalues @xmath382 and eigenvectors @xmath383 determine a set coupled of coupled equations satisfied by @xmath384 , from which the three - body problem can be solved . efimov scaling ratio @xmath385 as a function of the mass ratio for efimov states of two identical particles and another particle . the lower curve ( green ) corresponds to two identical bosons and one particle resonantly interacting with each other . the middle curve ( blue ) corresponds to two identical bosons interacting resonantly only with the other particle . the upper curve ( orange ) corresponds to two identical fermions resonantly interacting with another particle . the dashed curves show the results obtained from the born - oppenheimer approximation for large mass ratios . ] if the two identical particles are bosonic , then @xmath386 . for @xmath21 , the solutions of eq . ( [ eq : equationforphi2 + 1 ] ) are given by @xmath387 . the conditions resulting from eq . ( [ eq : betherpeierls2 + 1b ] ) can be written in a matrix form @xmath388\cdot\left(\!\begin{array}{c } \!f_{n}^{(2)}\!\\ f_{n}^{(1)}\ ! \end{array}\right)=0\label{eq : bethepeierls2boson+1}\ ] ] [ [ three - resonantly - interacting - pairs-1 ] ] three resonantly - interacting pairs + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + we first consider the case when all scattering lengths are resonant , @xmath389 . in the region of hyper - radius @xmath390 , the terms @xmath347 , @xmath391 in eq . ( [ eq : bethepeierls2boson+1 ] ) can be neglected , and the determinant of the matrix in that equation is : @xmath392 as in the case of three identical particles , this determinant admits an imaginary root @xmath128 . hence , the efimov effect occurs in this case , and the scaling ratio between efimov states at unitarity ( @xmath393 ) is shown in fig . [ fig:2 + 1 ] . in the case of equal mass @xmath394 , one retrieves the scaling ratio @xmath341 obtained for three identical bosons . this ratio is decreased by either decreasing the mass ratio @xmath395 ( it tends to @xmath396 in the limit @xmath397 ) or increasing the mass ratio ( it tends to 1 in the limit @xmath398 ) . [ [ two - resonantly - interacting - pairs-1 ] ] two resonantly - interacting pairs + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + we now consider the case when only the interaction between the particles of mass @xmath209 and mass @xmath9 is resonant , @xmath399 , while the interaction between identical particles is non - resonant , @xmath400 . in the region of hyper - radius @xmath401 , the term @xmath347 in eq . ( [ eq : bethepeierls2boson+1 ] ) may be neglected , whereas the term @xmath402 is very large and imposes @xmath403 . the remaining condition reads : @xmath404 which admits one imaginary solution @xmath128 . the efimov effect occurs in this case too , and the scaling ratio between efimov states at unitarity ( @xmath405 ) is shown in fig . [ fig:2 + 1 ] . since there are only two resonant pairs , the efimov attraction is weaker than for three resonant pairs , and for equal masses @xmath394 , one retrieves the scaling ratio @xmath353 obtained in section [ subsec:3-distinguishable - particles ] . for large mass ratios , the scaling ratio of trimer energies becomes the same as in the case of three - resonantly interacting pairs . this large - mass - ratio limit is interesting because the trimer spectrum is denser than that of identical bosons , allowing to more easily observe several efimov trimers . these trimers may be evidenced from the change in particle - dimer scattering length and relaxation rate , or three - body recombination rate @xcite . if the two identical particles are fermionic ( @xmath407 ) , there can not be any @xmath4-wave interaction between the two , which can be seen from the boundary condition eq . ( [ eq : bethepeierls2 + 1 ] ) , which imposes @xmath408 . for @xmath21 , the solutions of eq . ( [ eq : equationforphi2 + 1 ] ) are given by @xmath409 , with the following condition resulting from eq . ( [ eq : betherpeierls2 + 1b ] ) , @xmath410 this equation only admits real solutions , and thus there is no efimov attraction in this case . for @xmath406 , however , solutions of eq . ( [ eq : equationforphi2 + 1 ] ) are given by @xcite @xmath411 with the following condition resulting from eq . ( [ eq : betherpeierls2 + 1b ] ) @xmath412 this condition admits one imaginary solution @xmath128 for a mass ratio @xmath413 , where the critical mass ratio @xmath414 . although there is no efimov effect for mass ratios smaller than @xmath415 ( in particular no efimov effect in the equal - mass case ) , it occurs for mass ratios larger than the critical mass ratio @xmath415 . the corresponding scaling ratio at unitarity ( @xmath416 ) is shown in fig . [ fig:2 + 1 ] . it is infinitely large at the critical mass ratio and rapidly decreases to approach the scaling ratio for two bosons and one particle as the mass ratio is increased . from the preceding discussion , it appears that there is in general a competition between the efimov attraction and the centrifugal repulsion due to the angular momentum @xmath417 . for large enough mass ratios , the efimov attraction can overcome the centrifugal repulsion , gradually allowing the binding of efimov trimers with higher angular momentum @xcite . using the same approach as in the preceding discussion , one can determine from eq . ( [ eq : betherpeierls2 + 1b ] ) the critical mass ratios for the appearance of efimov trimers of increasing angular momenta . in the case of bosons , trimers with even angular momentum appear at the following critical mass ratios @xcite : @xmath418 in the case of fermions , trimers with odd angular momentum appear at the following mass ratios : @xmath419 in all three cases presented above and shown in fig . [ fig:2 + 1 ] , the efimov effect is strengthened as the mass ratio @xmath395 is increased . this can be simply understood from the born - oppenheimer approximation . this approximation exploits the fact that @xmath209 is much larger than @xmath9 in this limit : the heavy particles of mass @xmath209 can thus be treated as slow particles , and the particle of mass @xmath9 as a fast particle . the born - oppenheimer approximation consists in first solving the motion of the fast particle , for fixed positions of the heavy particles . let us call @xmath420 the relative position between the two heavy particles , and @xmath62 the relative position between their centre of mass and the light particle . the three - body wave function is approximated by the form : @xmath421 where @xmath422 is a solution of the problem for the light particle in presence of the heavy particles at a fixed separation @xmath420 . in the zero - range theory , this solution is a free wave satisfying @xmath423 with the bethe - peierls boundary condition eq . ( [ eq : bethepeierls ] ) between the heavy and light particles . the solution with the lowest energy @xmath424 is obtained with the following linear combination of two free waves originating from two sources at the locations of the heavy particles : @xmath425 where @xmath426 . applying the bethe - peierls boundary condition ( [ eq : bethepeierls ] ) to eq . ( [ eq : bondingorbital ] ) , one gets an equation for @xmath124 : @xmath427 the wave number @xmath124 , and thus the energy @xmath428 , are therefore functions of the separation @xmath429 between the two heavy particles . the @xmath72-dependent energy @xmath430 constitutes a potential energy for the relative motion of the two heavy particles , which obeys the following schrdinger equation , @xmath431 in addition to the potential @xmath430 induced by the light particle , there should also be a short - range interaction potential between the two heavy particles , but it is neglected here . the potential energy @xmath430 can be calculated analytically from eq . ( [ eq : bondingpotentialequation ] ) using the lambert function and is shown in fig . [ fig : bonding - potential ] for a positive scattering length . it is an attractive potential , whereas the potentials obtained for larger eigenvalues @xmath428 of eq . ( [ eq : freewavelightparticle ] ) are repulsive . for this reason , the lowest - eigenvalue solution eq . ( [ eq : bondingorbital ] ) is called a _ bonding orbital _ , to reflect the fact that the light particle in such a state acts as a glue between the two heavy particles . bonding potential @xmath430 in the born - oppenheimer approximation between two heavy particles separated by @xmath72 and both resonantly interacting with a light particle , with scattering length @xmath153 . at separation much smaller than the scattering length @xmath26 between the heavy and light particles , the heavy particles experience an efimov @xmath432 attraction . ] for large @xmath433 , one finds from eq . ( [ eq : bondingpotentialequation ] ) that @xmath434 showing the bonding potential @xmath430 asymptotes to the energy @xmath435 corresponding to a two - body bound state of light and heavy particles scattering with a free heavy particle at zero energy . moreover , the tail of the potential is as an attractive yukawa potential whose range is the scattering length @xmath26 . for small @xmath436 , on the other hand , one finds from eq . ( [ eq : bondingpotentialequation ] ) that @xmath437 approaches the omega constant @xmath438 , solution of the equation @xmath439 . the bonding potential is therefore @xmath440 . this reproduces the @xmath101 efimov attraction . hence , the born - oppenheimer approximation shows that the efimov attraction can indeed be interpreted as resulting from the exchange of the light particle between the two heavy particles . moreover , since @xmath430 is proportional to @xmath441 and the relative kinetic energy of the two heavy particles is proportional to @xmath442 , one can see from eq . ( [ eq : twoheavyparticlesequation ] ) that the efimov attraction is more effective for large mass ratios @xmath395 . more precisely , for a given partial wave @xmath443 with angular quantum number @xmath444 , this equation can be rewritten in a form similar to eq . ( [ eq : hyperradialequation2 ] ) , @xmath445 with the potential @xmath446 identification of this potential at small @xmath436 with the form of eq . ( [ eq : efimovattraction ] ) gives @xmath447 from which one can calculate the scaling factor @xmath385 associated with the @xmath101 attraction . effective potential @xmath448 in the born - oppenheimer approximation between two identical fermions separated by @xmath72 and resonantly interacting ( with a scattering length @xmath153 ) with a light particle , for various values of their mass ratio . this potential results from the competition between the bonding potential @xmath430 and the centrifugal repulsion with one unit of angular momentum - see eq . ( [ eq : heavyheavypotential ] ) . at short separations @xmath436 , the potential exhibits the @xmath96 efimov attraction for a mass ratio larger than the critical value @xmath449 ( corresponding to the red curve ) , while it is repulsive for smaller mass ratios . ] if the two heavy particles are distinguishable or identical bosons , one can take @xmath61 . the corresponding potential @xmath450 is purely attractive , as shown in fig . [ fig : bonding - potential ] . if the two heavy particles are identical fermions , there should be at least one unit of angular momentum between the two heavy particles to respect the antisymmetry of their wave function . there is therefore a competition between the efimov attraction and the centrifugal repulsion . the resulting potential @xmath448 is represented in fig . [ fig : heavy - heavy - potential ] for different values of the mass ratio . according to eq . ( [ eq : effectiveefimovcoefficient ] ) , the efimov attraction wins for large enough mass ratio @xmath395 . for @xmath451 , one obtains the critical mass ratio @xmath452 at which the potential becomes purely attractive , which is very close to the exact result @xmath414 presented in section [ subsec:2-fermions-1particle ] . above this critical mass ratio , the potential is dominated by the @xmath432 efimov attraction for @xmath436 , which leads to the efimov effect . the efimov scaling factor @xmath138 obtained from eq . ( [ eq : effectiveefimovcoefficient ] ) is shown by dashed curves in fig . [ fig:2 + 1 ] for both the bosonic @xmath61 and fermionic @xmath453 cases , and is in good agreement with the exact results for large mass ratios . the born - oppenheimer approximation thus gives a simple account of the efimov effect for 2 + 1 particles . as we saw in the preceding sections , a system of two identical fermions resonantly interacting with a light particle can be bound by the efimov effect when the mass ratio between the fermions and the light particle is larger than a critical value @xmath415 . nevertheless , even below the critical mass ratio , it is possible for the system to form universal three - body bound states with the same quantum numbers for @xmath153 . this fact was pointed out by oleg i. kartavtsev and anastasia v. malykh @xcite . it can be seen from the born - oppenheimer potential @xmath448 between the two fermions shown in fig . [ fig : heavy - heavy - potential ] . for a mass ratio smaller than @xmath415 , even though the centrifugal repulsion wins over the efimov attraction , making the potential repulsive at short separation , there can nonetheless be an attractive part at larger distances , thereby creating a potential well . this potential well can be seen in the curve corresponding to a mass ratio of 10 in fig . [ fig : heavy - heavy - potential ] . the potential well deepens as the mass ratio increases , until it becomes purely attractive at the critical mass ratio . kartavtsev and malykh have shown by solving the three - body problem exactly ( using the hyperspherical formalism sketched at the beginning of this section ) that a ground three - body bound state appears at the critical mass ratio @xmath454 , and an excited one appears at the mass ratio @xmath455 . since there is no efimov attraction at short distance for these states , there is no need to introduce a three - body boundary condition , and thus the states are universally determined by the scattering length @xmath153 between a fermion and the light particle . unlike efimov trimers , the energy of these trimer simply scales with the universal dimer energy . for this reason , they are called `` universal trimers '' . similar states appear for higher angular momenta at some critical mass ratios @xcite , connecting to the non - zero angular - momentum efimov trimers of section [ subsec : trimers - with - higher - angular - momentum ] appearing at larger mass ratios . the existence of these states have important consequences for inelastic three - body collisions by recombination into dimers @xcite and the scattering of dimers of fermions with another fermion @xcite , even at mass ratios slightly lower than @xmath456 , as was confirmed experimentally @xcite . however these states have not been directly observed yet . it should be noted that the universality of these states is in practice limited to very large scattering lengths @xcite . although there is formally no need to introduce a short - range three - body boundary condition for the universal states , such condition exists physically at a separation of the particles on the order of the interaction range @xmath10 . even when the scattering length is more than ten times that range , the trimers may be significantly affected by the three - body boundary condition . in ref . @xcite the 2 + 1 fermions problem was solved with a three - body boundary condition implemented by imposing a cutoff at some momentum @xmath457 . for mass ratio @xmath458 , a trimer was found to exist on the positive scattering length side and shows the universal features predicted by kartavtsev and malykh when the scattering length is very large @xmath459 ( see fig . [ fig : mass - imbalanced - fermions ] ) . as the scattering length is tuned away from unitarity , however , the binding energy of the trimer gets smaller than that of the universal trimer , due to the three - body boundary condition . a similar behaviour is found for mass ratios @xmath460 , where two universal trimers appear near unitarity ( see the central column of fig . [ fig : mass - imbalanced - fermions ] ) but gradually turn into what the authors of ref . @xcite called `` crossover trimers '' , which end up dissociating into a fermion and a fermion - light - particle dimer as the scattering length is varied further . the crossover trimers depend on the three - body parameter set by the three - body bounary condition and smoothly connect the universal trimers to the efimov trimers appearing at larger mass ratio @xmath461 : as the mass ratio is increased from below with a fixed positive scattering length , the universal trimers become more and more sensitive to the three - body parameter , turning into the crossover trimer states , and then at @xmath461 turn into the ground and first excited states of the efimov trimers ( the second and higher excited efimov trimers start to appear at @xmath462 ) . this scenario illustrated in fig . [ fig : mass - imbalanced - fermions ] describes how the two universal trimers for @xmath463 smoothly connect to an infinite series of efimov states for @xmath462 . the 2 + 1 fermions problem was subsequently studied by arghavan safavi - naini and co - workers in ref . @xcite with a general three - body boundary condition implemented by setting the logarithmic derivative of the hyper - radial wave function at distance on the order of @xmath10 . while this work confirmed that the trimers behave universally when @xmath459 and that they tend to become more sensitive to the three - body parameter as the mass ratio is increased towards @xmath415 , there are some notable differences compared to the above work @xcite . in addition to the universal trimers , an additional `` non - universal '' trimer may exist . here , non - universal means that it strongly depends on the three - body boundary condition in addition to the scattering length @xmath26 . as the value of the three - body boundary condition is varied , the non - universal trimer makes avoided crossings with the universal trimers , and shift their energies away from the universal predictions . in contrast to the momentum cutoff method of ref . @xcite , the shift can be either positive or negative depending on binding energy of the non - universal state . when it is bound deeper than the universal trimers , it pushes up their energies . on the contrary , it pushes down the energies of the universal trimers when it lies above them . in the limit where the scattering length @xmath26 is much larger than @xmath10 , the three - body boundary condition can be implemented as a zero - range boundary condition parameterised by a three - body parameter @xmath113 ( as in eq . ( [ eq : f0bis ] ) ) for mass ratios larger than @xmath464 , because both the regular solution ( which vanishes at small hyper - radius ) and the irregular solution ( which diverges at small hyper - radius ) are square - integrable in this case @xcite . the precise energy spectrum in this limit for all possible values of @xmath465 and all mass ratios @xmath466 has recently been calculated by kartavtsev and malykh @xcite for both @xmath153 and @xmath151 . in some range of @xmath465 , the trimers may appear , like efimov states , at a negative scattering length instead of being restricted to @xmath153 . for @xmath467 , one retrieves the universal results . to answer which kind of three - body boundary condition should be taken for a given physical system , one needs further knowledge on the microscopic details of the system in question . indeed , recent works on the microscopic origin of the three - body parameter suggest that pairwise interactions inducing a significant drop of probability at short pair separation create an effective repulsive barrier that serves as a three - body boundary condition . this subtle effect is discussed in detail in section [ sec : what - sets - the-3bp ] . whether it is also relevant here is an open question . in many systems occurring in nature , particles have an internal spin that complicates somewhat their description . in many cases , the interaction between two particles 1 and 2 is rotationally invariant , and thus does not depend on the spin projection numbers but only on the spin quantum number @xmath4 for the total spin of the two particles . for example , for particles with spin 1/2 , there are two interaction potentials : the singlet potential ( for @xmath468 ) and the triplet potential ( for @xmath469 ) . a general treatment of the resonantly - interacting three - body problem with spin has been given by bulgac and efimov @xcite . in general , for a given total spin @xmath470 of the three - body system , one can generalise the faddeev decomposition of eq . ( [ eq : faddeevdecomposition ] ) as follows @xcite : @xmath471 the states @xmath472 denote three - spin states of total spin quantum number @xmath470 and spin quantum number @xmath4 for the pair @xmath473 . for a given pair @xmath473 , these states form a basis of the three - spin space of total spin @xmath470 . one can thus express the states for the other pairs as a linear combination of the states for that particular pair . in section [ subsec : triton ] , we illustrate this by treating the specific example of the triton . in some other cases , such as in the presence of a magnetic field that strongly breaks the rotational invariance , the pairwise interaction can be assumed to depend only on the spin projections ( magnetic quantum number @xmath9 ) of the two particles . then , each spin projection can be regarded as a different kind of particle , and the situation is equivalent to the cases discussed in sections [ subsec:3-distinguishable - particles ] , [ subsec:2-bosons+1particle ] , and [ subsec:2-fermions-1particle ] . for instance , in the experiments discussed in section [ subsec : observations - in - nuclear - multi - component ] of lithium-6 atoms in a magnetic field , polarised in three different hyperfine states @xmath474 , @xmath475 , and @xmath476 , the pairwise interaction just depends on the hyperfine states of the pair @xcite . although the atoms are fermionic , the fully antisymmetrised wave function for three atoms in three different spin states reads : @xmath477 and therefore is equivalent to a single wave function @xmath82 describing a system of three distinguishable particles , with identical masses but three different scattering lengths @xmath478 @xmath327 , and @xmath328 - see section [ subsec:3-distinguishable - particles ] for the derivation of the efimov effect in this system . spin - orbit interaction is the coupling between a particle s spin and its motion . it occurs for charged particles such as electrons in atoms and solids , as well as nucleons inside a nucleus . in the recent years , it has also been possible to create artificial spin - orbit interaction for neutral atoms using laser techniques @xcite . the influence of the spin - orbit interaction on efimov physics was addressed by zhe - yu shi , xiaoling cui , and hui zhai @xcite . they considered a system of two heavy fermions resonantly interacting with one light particle , in which the light particle is a spin-1/2 particle subject to an isotropic spin - orbit interaction of the form @xmath479 , where @xmath480 is the particle s momentum and @xmath481 its spin . from their calculations , some general conclusions can de drawn . first of all , the spin - orbit interaction lowers the energy of the heavy - light dimer and heavy - heavy - light trimers . however , the spin - orbit interaction competes with the efimov attraction and reduces the binding energy of efimov trimers with respect to the particle - dimer threshold . since the spin - orbit interaction only affects large distances , while the efimov attraction persists at shorter distances , the critical mass ratio @xmath415 for the onset of efimov states , the discrete scale invariance and scaling ratio @xmath138 remain unchanged . the discrete scale invariance is however broken below a certain energy scale associated with the coupling strength @xmath106 , making the number of trimers finite , as the excited trimers are pushed into the particle - dimer threshold . on the other hand , below the critical mass ratio , the spin - orbit interaction favours the appearance of kartavtsev - malykh - like universal trimers in a broader range of scattering lengths and mass ratios . in the presence of spin - orbit coupling , these universal trimers not only exist for positive scattering lengths but in a range of negative scattering lengths as well , and the ground - state trimer appears at mass ratio 2.68 ( for the state with total angular momentum @xmath482 ) and 5.92 ( for @xmath483 ) . so far , all known multicomponent systems in nuclear physics related to efimov physics involve two neutrons as two of the three particles . neutrons are favourable for the following reasons : * first of all , the interaction between two neutrons is resonant , the basic requirement for efimov physics , since the neutrons can almost form a two - body bound state . * second , they carry a spin 1/2 , and can therefore be in two distinguishable states , or more precisely they can form a spin singlet state . this particular configuration is free of the centrifugal repulsion that is otherwise present for fermions in a triplet state ( such as two identical fermions ) and would suppress the efimov attraction . * third , neutrons having no electrical charge , unlike protons , they do not have any coulomb repulsion between themselves and other particles , that would compete with the efimov attraction . the simplest case is the third particle being another nucleon . it can not be a neutron , since it would have to be in the same spin state as one of the two others , and the resulting fermi repulsion would suppress the efimov attraction . as seen in section [ subsec:2-fermions-1particle ] , the efimov attraction for two identical fermions and one particle of equal mass is not strong enough to overcome the fermi repulsion . as a matter of fact , there is no bound state of three neutrons . the third nucleon therefore has to be a proton , and the three - body system corresponds to the triton , the nucleus of tritium @xmath484 . the triton was considered in vitaly efimov s original work as a possible candidate for efimov state . here , we show how the efimov attraction explains the binding of the triton and roughly reproduces its binding energy . we first derive the efimov attraction in the zero - range theory of two neutrons and one proton , and show that is the same as for three identical bosons . then , we take into account the finite - range corrections , and show how the triton fits in the efimov spectrum . [ [ efimov - attraction - in - the - triton ] ] efimov attraction in the triton + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + systems of nucleons are often described as identical particles with an internal property called isospin , which distinguishes between the neutron state and proton state as different projections of a formal spin 1/2 . this is possible because protons and neutrons have nearly the same mass , and nuclear interactions are approximately the same for protons and neutrons , and thus nearly isospin - symmetric . the isospin symmetry has been further confirmed to originate from the symmetries of quantum chromodynamics ( qcd ) describing nucleons as made of quarks . in the zero - range theory , however , the isospin formalism is not essential , as the nuclear interactions turn out to depend only on spin at this simple level of description . for the sake of readers unfamiliar with isospin , we shall simply describe the triton as two identical fermions ( two neutrons ) and a distinguishable fermion ( proton ) , and assume that the pairwise nuclear interaction depends only on the total spin quantum number of two nucleons . we also assume the neutron and the proton to have the same mass @xmath9 . for a treatment with isospin , we refer the readers to refs . @xcite . each nucleon carries a spin 1/2 , whose projection on a fixed axis can be either up @xmath485 or down @xmath486 . the triton is characterised by a total spin @xmath470 equal to @xmath487 , and a projection @xmath488 . therefore , its wave function can be expressed on the spin basis states , @xmath489 which are obtained by standard summation of spins using clebsh - gordan coefficients . here , we assume that particle 1 is the proton , and particles 2 and 3 are the two neutrons . as can be seen from the above expressions , @xmath490 corresponds to a spin singlet state of the two neutrons , whereas @xmath491 corresponds to a spin triplet state . the total wave function of the triton is thus : @xmath492 and has to be antisymmetric under the exchange of the two neutrons , particles 2 and 3 . since the singlet and triplet states are respectively antisymmetric and symmetric under such exchange , as can be checked from eqs . ( [ eq : spinsingletstate]-[eq : spintripletstate ] ) , @xmath493 and @xmath494 have to be symmetric and antisymmetric , respectively . the faddeev decompositions of @xmath493 and @xmath494 that preserve their symmetries are : @xmath495 where @xmath54 and @xmath136 are respectively even and odd functions of @xmath496 . one can see that the spin singlet configuration allows the spatial configuration @xmath493 to have the bosonic exchange symmetry when @xmath497 , as in eq . ( [ eq : faddeevdecomposition ] ) , which in turn allows the efimov effect to occur . in the zero - range theory , @xmath493 and @xmath494 each satisfy the free schrdinger equation - see eq . ( [ eq : freeschrodingereqpsi ] ) - with the bethe - peierls boundary conditions for the contact of two nucleons , either in the singlet or triplet spin state . in the case of the neutron - neutron interaction , these conditions are readily expressed as : @xmath498 where @xmath499 and @xmath500 are the nucleon singlet and triplet @xmath4-wave scattering lengths . one can then proceed as in section [ subsec : efimov - theory ] , retaining only the zero - angular momentum contribution of the faddeev components of @xmath493 and @xmath494 , i.e. assuming the form of eq . ( [ eq : swavechi ] ) , and using hyper - spherical coordinates eq . ( [ eq : hypersphericalcoordinate1]-[eq : hypersphericalcoordinate2 ] ) . this gives a boundary condition analogous to eq . ( [ eq : hypersphericalcondition ] ) for the singlet interaction , @xmath77_{\alpha\to0}+\frac{8}{\sqrt{3}}\phi_{0}\!\left(\!\!\!\begin{array}{c } r,\frac{\pi}{3}\end{array}\!\!\!\right)=\!-\frac{r}{a_{s}}\chi_{0}(r,0)\label{eq : neutronneutronhypersphericalcondition}\ ] ] for the triplet interaction , eq . ( [ eq : neutronneutrontripletcondition ] ) gives no constraint on @xmath494 because it is antisymmetric under the exchange of the two neutrons , i.e. @xmath501 when @xmath502 . this expresses the fact that for zero - range interactions neutrons interact only in the singlet state . for this reason , we can simply set @xmath503 . in the case of proton - neutron interactions , we first have to rotate the spin basis to obtain states that are singlet and triplet states of the proton - neutron subsystem ( say , particles 1 and 2 ) : @xmath504 this gives @xmath505 with @xmath506 the boundary conditions are then expressed as : @xmath507 this gives @xmath508_{\alpha\to0}\!\!\!+\frac{4}{\sqrt{3}}\left(\chi_{0}+\phi_{0}+\sqrt{3}\zeta_{0}\right)(r,\frac{\pi}{3})=-\frac{r}{a_{s}}\left(\phi_{0}-\sqrt{3}\zeta_{0}\right)(r,0),\label{eq : protonneutronhypersphericalcondition1}\ ] ] @xmath509_{\alpha\to0}\!\!\!+\frac{4}{\sqrt{3}}\left(\chi_{0}+\phi_{0}-\frac{\zeta_{0}}{\sqrt{3}}\right)(r,\frac{\pi}{3})=-\frac{r}{a_{t}}\left(\phi_{0}+\frac{\zeta_{0}}{\sqrt{3}}\right)(r,0).\label{eq : protonneutronhypersphericalcondition2}\ ] ] combining eqs . ( [ eq : neutronneutronhypersphericalcondition ] ) and ( [ eq : protonneutronhypersphericalcondition1 ] ) , one obtains a closed condition @xmath510_{\alpha\to0}-\frac{4}{\sqrt{3}}\tilde{\chi}_{0}\!\left(\!\!\!\begin{array}{c } r,\frac{\pi}{3}\end{array}\!\!\!\right)=\!-\frac{r}{a_{s}}\tilde{\chi}_{0}(r,0)\ ] ] for the quantity @xmath511 . unlike eq . ( [ eq : hypersphericalcondition ] ) for the bosonic case , this condition itself only yields real eigenvalues @xmath86 which do not lead to the efimov effect . however , unlike the bosonic case , this condition admits the extra solution @xmath512 , which does not set the total wave function to zero . in the language of isospin symmetry , this corresponds to considering states with total isospin @xmath513 . making this choice , the two remaining conditions are : @xmath514_{\alpha\to0}+\frac{8}{\sqrt{3}}\phi_{0}(r,\frac{\pi}{3})=-\frac{r}{a_{s}}\chi_{0}(r,0),\ ] ] @xmath515_{\alpha\to0}+\frac{4}{\sqrt{3}}\left(-4\chi_{0}-2\phi_{0}\right)(r,\frac{\pi}{3})=-\frac{r}{a_{t}}\left(-4\phi_{0}+\chi_{0}\right)(r,0).\ ] ] setting @xmath516 and @xmath517 , one obtains @xmath518 @xmath519 where @xmath520 . these equations were first presented in efimov s original work @xcite , although their integral version in momentum space had been derived thirteen years earlier by skorniakov and ter - martirosian @xcite . as shown in section [ subsec : efimov - theory ] , the advantage of this form is that one can immediately conclude that the system features the efimov attraction . indeed , as anticipated from the symmetry of eq . ( [ eq : tritonpsis ] ) , when both the singlet and triplet scattering lengths are infinite , eq . ( [ eq : tritoncondition1 ] ) is identical to that of bosons at unitarity eq . ( [ eq : hypersphericalcondition ] ) . therefore , _ there occurs an efimov attraction of the same strength as identical bosons , leading to the same scaling ratio @xmath341 in the energy spectrum_. [ [ finite - range - corrections-1 ] ] finite - range corrections + + + + + + + + + + + + + + + + + + + + + + + + the above zero - range theory predicts the existence of a two - body bound state of neutron and proton ( the deuteron ) , since @xmath521 , as well as possible efimov three - body bound states of two neutrons and one proton . using the deuteron energy @xmath522 mev and neutron - deuteron spin - doublet scattering length @xmath523 fm as experimental inputs to determine respectively the values of @xmath500 and the three - body parameter in the zero - range theory , one finds one efimov trimer , and its energy 8.1 mev @xcite is within 5% that of the triton , @xmath524 mev . however , this theory is only qualitative . for instance , using the value @xmath525 fm @xcite , the predicted binding energy from eq . ( [ eq : universaldimerenergy ] ) for the deuteron is @xmath526 which significantly differs from the experimental value 2.224 mev . this means that non - zero range corrections are important . the effective range theory is more quantitative . from eq . ( [ eq : lowenergyphaseshift ] ) , with the triplet effective range @xmath527 fm @xcite , one obtains the binding energy in the effective range approximation @xmath528 which is remarkably close to the experimental value . taking the effective range correction to first order only , one finds : @xmath529 which differs by 15% from the experimental value . as discussed in section [ subsec : finite - range - interactions ] , the first - order effective - range correction may also be taken into account in the three - body calculations @xcite . using @xmath530 as the three - body input , and @xmath531 fm @xcite and @xmath532 as two - body inputs , v. efimov and e. g. tkachenko @xcite obtained 8.8 mev for the energy of the trimer ( using @xmath533 fm and @xmath534 fm ) , while p. .f . bedaque and co - workers @xcite obtained 8.3 mev ( using @xmath535 fm and @xmath536 ) in the framework of effective field theory . thus , once the effective - range corrections are taken into account , the predicted trimer energy remains just a few percent away from the triton energy . that is because the main effect of range corrections is to shift both the dimer and trimer energies by a similar amount . _ these results show that the binding of the triton is consistent with the efimov scenario_. [ [ explanation - of - the - phillips - line ] ] explanation of the phillips line + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + the zero - range theory , with or without finite - range corrections , requires a three - body input to set the three - body energy , such as the neutron - deuteron spin - doublet scattering length @xmath530 . it therefore implies a correlation between the trimer energy and that scattering length . such correlation was observed numerically for three - nucleon systems and known as the phillips line @xcite . if one plots the results for the triton energy @xmath537 and neutron - deuteron scattering length @xmath530 obtained from various nucleon - nucleon potential models , one finds that the points @xmath538 tend to form a line . v. efimov and e. g. tkachenko @xcite pointed out that the zero - range theory gives a natural explanation for this fact . since different nucleon - nucleon potentials lead to slightly different scattering lenths and three - body parameters , their results sample a small portion of the curve relating @xmath537 to @xmath530 in the zero - range theory , thus forming a small line . the fact that they do so shows the relevance of the zero - range picture for these systems . [ [ triton - and - deuteron - in - the - efimov - spectrum ] ] triton and deuteron in the efimov spectrum + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + to visualise how the triton and deuteron fit into the efimov spectrum , we have represented in fig . [ fig : triton ] the energy spectrum of two neutrons and one proton as a function of @xmath539 and @xmath540 . to take into account the effect of the effective range , the energy is calculated using a separable interaction model @xcite ( see appendix for details ) , which is parameterised to reproduce the values @xcite of the effective ranges @xmath527 fm and @xmath541 fm at the physical values of @xmath500 and @xmath499 . such a model accurately reproduces the effective - range approximation of dimer energy eq . ( [ eq : effectiverangedeuteron ] ) . moreover , it determines the trimer energy without requiring to set a three - body parameter from a three - body input . the trimer energy depends on the particular form of the separable interaction @xcite , but as we shall see in section [ subsec : other - types - of - interactions ] , it is roughly determined by the effective ranges only . the energy surfaces shown in fig . [ fig : triton ] are the ground and excited trimers and the singlet and triplet dimers . near the unitarity point @xmath542 , the spectrum is discrete - scale - invariant by simultaneous scaling of @xmath499 and @xmath500 by a factor of @xmath341 . the physical values of @xmath499 and @xmath500 correspond to a vertical line in that figure , where the experimental energies of the deuteron and the triton are indicated . from this figure , one can conclude that _ the deuteron is the triplet dimer , and the triton connects to the ground state of an efimov series of trimers _ which accumulates at @xmath543 . to reproduce the experimental properties of the deuteron and the triton with a higher accuracy , it is of course necessary to construct more sophisticated models building in the details of nuclear interactions ( three - body force in particular ) , coupling of partial waves , the difference of mass between the proton and the neutron , etc . nonetheless , the efimov scenario gives a simple understanding of the deuteron and the triton . other candidates for efimov physics in nuclear systems are halo nuclei @xcite . halo nuclei are exotic nuclei discovered from the 1980s , which have an anomalously large mean radius and small binding energy . they usually correspond to neutron - rich or proton - rich nuclei , or excited states of normal nuclei , which means that their lifetime is usually short , on the order of a few up to hundreds of milliseconds . light halo nuclei are shown in fig . [ fig : table - of - nuclides ] . numerous experiments and analyses have determined that they can be described as a compact core nucleus surrounded by one or few loosely bound nucleons forming a diffuse halo around the core @xcite . examples of one - neutron halos are beryllium-11 and carbon-19 . examples of two - neutron halo nuclei are helium-6 , lithium-11 , boron-17 , boron-19 and carbon-22 . helium-8 is considered to be a four - neutron halo nucleus . at first sight , halo nuclei look very similar to the situation described by the zero - range theory of section [ subsec : efimov - theory ] . the one - neutron halos can be recognised as the universal dimer supported by a resonant short - range interaction , assuming that the effective interaction between the neutron and the core is resonant in the @xmath4 wave . it is thus tempting to identify the two - neutron halo nuclei with efimov states composed of a core and two neutrons , in accordance with the discussion at the beginning of section [ subsec : observations - in - nuclear - multi - component ] . this identification would naturally explain a number of features such as the large extent of halo nuclei and the borromean nature of some of them . however , there may also be significant differences preventing the identification of halo nuclei with efimov states . for instance , the two - neutron halo nucleus of helium-6 is known to feature a @xmath288-wave resonance between the core and one neutron , in addition to their @xmath4-wave interaction . as seen in section [ subsec : resonant - p - wave - interactions ] , @xmath288-wave resonances do not lead to the discrete scale invariance of efimov physics . therefore , halo nuclei such as helium-6 can not be considered as efimov states , although they may be described by universal models @xcite . another difficulty is that one would expect to find efimov states by adding one neutron to the one - neutron halo nuclei @xmath544be and @xmath545c , but @xmath546be and @xmath547c are not currently recognised as two - neutron halo nuclei . it is usually thought that for these systems , the second neutron forms a cooper pair with the first neutron , which condenses with the other pairs of the core , making the nucleus more compact . however , it is not excluded that @xmath546be and @xmath547c may constitute efimov ground states nonetheless . indeed , the experimental characterisation of halo nuclei relies on the measurement of anomalously large cross sections and narrow momentum distributions of neutrons . while such features are expected for a ground efimov state close to the two - body or three - body thresholds where its size becomes very large , the ground efimov state for interactions near unitarity is relatively compact , with a typical size only marginally larger than the range of interactions . this situation could explain why the nuclei obtained by adding one neutron to a one - neutron halo nucleus are more compact and not recognised as halo states . the assumption that the core remains inert in such compact states is however questionable . on the other hand , there exist two - neutron halo nuclei , such as @xmath544li and @xmath548c , with no corresponding one - neutron halo nucleus . these nuclei could therefore correspond to borromean efimov states of a core and two neutrons , for which the core - neutron subsystems are unbound but have a virtual state close to threshold ( such as @xmath549li which is observed as a resonance ) . such efimov states are typically much larger in size than the range of interactions , which would explain the halo structure of these nuclei . in summary , although not all two - neutron halo nuclei are manifestations of efimov states ( @xmath319he is not ) , some halo nuclei ( such as @xmath544li and @xmath548c ) are possibly ground - state efimov trimers in the borromean regime , and other nuclei which are not experimentally regarded as halo nuclei ( such as @xmath546be and @xmath547c ) could be ground - state efimov trimers close to the unitary limit . for these nuclei , all interactions ( core - neutron and neutron - neutron ) are assumed to be resonant , and the neutrons can be in a symmetric state ( spin singlet ) . if the core has spin zero , the situation is equivalent to that of two identical bosons and one particle with three resonantly - interacting pairs , as described in section [ subsec:2-bosons+1particle ] and illustrated in fig . [ fig:2 + 1 ] . since the core is at least nine times heavier than the neutron , the efimov scaling ratio @xmath106 when both the neutron - neutron and core - neutron scattering lengths are infinite should be close to the limiting value @xmath550 for small mass ratios , which is marginally smaller than the scaling ratio for identical bosons @xmath551 . as discussed in section [ subsec : what - is - an - efimov - state ] , the ground state of an efimov series , though more easily observable , is difficult to characterise as an efimov state due to important finite - range corrections . the excited states , on the other hand , conform more clearly to the universal properties of efimov states , but are less likely to exist and more difficult to observe . [ [ efimov - models - of - nuclei ] ] efimov models of nuclei + + + + + + + + + + + + + + + + + + + + + + + the first theorists to consider the possibility of efimov nuclei made of a core plus two neutrons under these assumptions are dmitri v. fedorov , aksel s. jensen , and karsten riisager @xcite in 1994 . they solved the faddeev equations for such three - body system , assuming gaussian potentials for the neutron - neutron and neutron - core interacions , and concluded that @xmath552be , @xmath553c and @xmath547c are possible candidates for efimov states . the efimov character of nuclei such as @xmath544li , @xmath552be , and @xmath548c was also investigated using three - body models with separable interactions @xcite . in 1997 , a. e. a. amorim , tobias frederico , and lauro tomio @xcite solved the same three - body problem for zero - range interactions , and plotted the region of existence of the @xmath554th efimov state , which is universally determined by the core - neutron and neutron - neutron scattering lengths normalised by the @xmath5th efimov state s energy . assuming that nuclei such as @xmath546be , @xmath553c , @xmath547c are ground - state efimov trimers ( @xmath555 ) , and using the measured energies of core - neutron bound states ( or virtual states ) and neutron - neutron scattering length , the authors could represent the locations of these nuclei in this plot . only one nucleus , carbon-20 , enters the region of existence of the first excited efimov state ( @xmath556 ) . carbon-20 lies in fact just at the region boundary , and the large uncertainty on the core - neutron bound state energy ( the one - neutron halo nucleus of carbon-19 ) makes it possible for an excited efimov trimer state to exist either as a bound state or a virtual state @xcite . in 2008 , david l. canham and hans - werner hammer @xcite refined the zero - range calculations of amorim and co - workers in the framework of effective - field theory and estimated the errors due to finite - range corrections . the same authors included the finite - range corrections explicitly in a later work @xcite . they reached the same conclusion that among the nuclei @xmath544li , @xmath546be , @xmath552be , @xmath553c , and @xmath547c , carbon-20 is the only candidate for the existence of an excited efimov state . as mentioned before , this analysis assumes that the ground state of these nuclei is a ground efimov state , _ i.e. _ the three - body parameter of the zero - range theory is adjusted to reproduce the ground - state energy of these nuclei . even if the ground state of @xmath547c turns out to be a compact nucleus that has no connection with the efimov attraction , it could be that an excited state features two neutrons sufficiently far from the core to conform to the structure an efimov excited state . in this case , however , the ground - state energy of @xmath547c can not be used to predict the energy of that excited state . in 2010 , carbon-22 was experimentally identified as a two - neutron halo nucleus , exhibiting a root - mean - square matter radius of @xmath557 fm @xcite . although its two - neutron separation energy has not been measured , the radius value could be used to parameterise three - body models @xcite , constraining the two - neutron separation energy to be smaller than 100 kev . this small two - neutron separation energy imposes the core - neutron scattering length to be very large ( corresponding to a virtual state energy well below 1 kev ) in order to allow an excited efimov state . experimental data indicates that this is not the case @xcite , and it is thus likely that carbon-22 , like all other borromean two - neutron halo nuclei , does not admit an excited efimov state . [ [ comparison - with - experiments ] ] comparison with experiments + + + + + + + + + + + + + + + + + + + + + + + + + + + the fitting of a single observable such as the energy or the radius of the nucleus does not of course demonstrate the validity of the three - body models . to confirm the assumption that the ground state of the considered nuclei is an efimov trimer , the authors of the above - mentioned works have calculated various structural properties from their three - body model , in order to compare them with experimental data for these nuclei . in particular , they considered the root mean square radii @xmath558 and @xmath559 of the neutrons and core from the centre of mass , the root mean square @xmath560 and @xmath561 of the neutron - neutron and neutron - core distances , as well as the opening angle @xmath562 between the two neutrons @xcite . for @xmath544li , the three - body models ( with and without range corrections , as they turn out to be small ) give @xmath563 fm , in fair agreement with the experimental values @xmath564 fm and @xmath565 fm reported in refs . @xcite . these results show that the basic properties of the candidate halo nuclei look indeed consistent with efimov states . the question whether these nuclei can be considered as efimov states will be answered more clearly in the coming years as more experimental data to compare with becomes available , and more comparison between three - body models and more microscopic models like shell models are developed . [ [ potassium - rubidium - mixtures ] ] potassium - rubidium mixtures + + + + + + + + + + + + + + + + + + + + + + + + + + + the efimov states of a mass - imbalanced system have been observed in ultra - cold mixtures of potassium and rubidium atoms @xcite , in which the external magnetic field is tuned close to a feshbach resonance between the potassium and rubidium atoms . if both potassium and rubidium atoms are bosonic , as is the case for @xmath566 , @xmath567 , and @xmath568 atoms , two kinds of efimov trimers are possible : krbrb and kkrb , corresponding respectively to two heavy bosons plus one light particle , and two light bosons plus one heavy particle . therefore , the ground - state trimers of these two efimov series should appear at the three - body threshold at some negative scattering length @xmath569 and @xmath570 . as the inverse of the potassium - rubidium scattering length is continuously varied from negative to positive values , these trimers may break up into an atom and a dimer at some positive scattering lengths @xmath571 and @xmath572 . this implies that atom losses in the mixture due to recombination into deeper states are enhanced when the scattering length is tuned around one of these scattering lengths , i.e. one expects to observe peaks in three - body recombination loss rate at @xmath569 and @xmath570 for the atomic mixture , and peaks in the atom - dimer relaxation loss rate at @xmath571 ( @xmath572 ) for a mixture of rubidium ( potassium ) atoms and krb dimers . a three - body calculation using potentials with a van der waals tail @xcite has shown that @xmath573 and @xmath574 ( where @xmath575 is the bohr radius ) . it is currently not possible to observe the three - body loss peaks associated with these negative scattering lengths and @xmath576 which they assigned to @xmath569 and @xmath570 , respectively . these values , however , turned out to be too small in magnitude compared to the theoretical values . furthermore , no three - body loss peak has been observed in any potassium ( @xmath566,@xmath577,@xmath567 ) rubidium-87 mixture by any of the subsequent experiments in the groups of deborah jin at jila @xcite , shin inouye at the university of tokyo @xcite , and jan arlt at aarhus university @xcite . the work of ref . @xcite suggests that the peaks observed by the florence group are due to two - body resonances with a @xmath288-wave molecular state . ] , since it is experimentally difficult to tune the magnetic field to such large values of the scattering length and reach a temperature that is low enough to resolve the peaks . on the other hand , the positive scattering lengths @xmath571 and @xmath572 take experimentally accessible values . in 2013 , the group of deborah jin at jila measured the three - body loss rate and the atom - dimer relaxation rate in a mixture of potassium-40 and rubidium-87 atoms . note that potassium-40 is fermionic , so that the efimov effect only occurs for krbrb in this system . while they could not find any evidence of three - body loss peaks for @xmath578 @xcite , they observed a peak in the atom ( @xmath568 ) - dimer ( @xmath579 ) relaxation rate at the positive scattering length @xmath580 @xcite . more recently , the group of shin inouye at the university of tokyo has also found a peak in the atom - dimer relaxation rate in a @xmath581 mixture at a similar position @xmath582 @xcite . this agreement can be naturally explained if we interpret these peaks as induced by the efimov states : since the atoms in both experiments are of the same atomic species with nearly the same mass , and the interatomic interactions should have almost the same van der waals tail , one naturally expects on the basis of van der waals universality ( see section [ subsec : van - der - waals - universality ] and ref . @xcite ) that both experiments would yield essentially the same results for the krbrb efimov physics . indeed , both peak positions are found to be consistent with @xmath571 obtained by a multi - channel three - body calculation using a van der waals type of potential @xcite . the efimov states of rbkk , corresponding to the `` efimov - unfavoured '' case of one heavy and two light particles , have yet to be observed . [ [ lithium - cesium - mixtures ] ] lithium - cesium mixtures + + + + + + + + + + + + + + + + + + + + + + + in 2014 , in two independent experiments , one led by cheng chin at the university of chicago @xcite and the other led by matthias weidemller at the university of heidelberg @xcite , experimentalists investigated mixtures of cesium-133 and lithium-6 , taking advantage of the large mass ratio to more easily observe efimov states since the scaling ratio is only 4.88 ( compared to 22.7 for bosons of equal mass ) . both groups were able to observe three peaks in the atom losses , corresponding to three efimov states , when the intensity of the external magnetic field is tuned near a feshbach resonance at @xmath583 g , although the authors of ref . @xcite could not confirm the validity of the third peak after a careful analysis of the three - body loss rate . the measured ratio of scattering lengths between the first and second peak was found to be 5.1(2 ) in ref . @xcite and 5.07(6)(13)(2 ) in ref . @xcite , close to the theoretical value 4.88 . the ratio for the second and third peaks in ref . @xcite was found to be 4.8(7 ) . this is so far the most relevant experimental demonstration of the efimov effect in its strictest sense ( definition 1 of section [ subsec : what - is - an - efimov - state ] ) , which is the geometric accumulation of trimer states below the three - body threshold . [ [ lithium - rubidum - mixtures ] ] lithium - rubidum mixtures + + + + + + + + + + + + + + + + + + + + + + + + in 2015 , the group of c. zimmermann in tbingen @xcite reported the signature of a heavy - heavy - light ground - state efimov trimer in an ultra - cold mixture of lithium-7 and rubidium-87 . the loss peak associated with that trimer was found at @xmath584 , which is consistent with the value expected from van der waals models , providing further experimental support for the van der waals universality of the three - body parameter discussed in section [ subsec : van - der - waals - universality ] . three experimental groups working on ultra - cold lithium-6 have independently evidenced the presence of efimov states made of three distinguishable atoms near broad feshbach resonances : the group of selim jochim in heidelberg @xcite , the group of kenneth m. ohara at the pennsylvania state university @xcite , and the group of takashi mukaiyama at the university of tokyo @xcite . in all experiments , the atoms were prepared in three different hyperfine sublevels , making it possible for three distinguishable particles to form efimov trimers , as detailed in section [ subsec:3-distinguishable - particles ] . this also makes the system more unstable by three - body recombination , since nothing prevents three distinguishable particles from approaching each other , unlike the two - component fermi systems where two of three particles are in the same state and therefore undergo fermi exclusion that limits the three - recombination processes . the experimentalists thus found the first indications of efimov physics in the strong variation of the three - body losses with external magnetic field . as the intensity of the magnetic field is varied , the scattering lengths between each pair of states is strongly altered , due to the presence of a broad feshbach resonance for each scattering length . these broad resonances overlap in the range @xmath585 gauss ( region 1 ) , where all three scattering lengths are much larger than the range of atomic interactions , but also make the three scattering lengths relatively large in the range @xmath586 gauss ( region 2 ) . efimov physics is therefore possible in these two regions . if the three scattering lengths diverged at the same intensity of the magnetic field , one could expect an infinity of efimov trimers in principle , as in the case of identical bosons . however , since the scattering lengths diverge at different intensities of the magnetic field , only a finite number of trimers is expected . as it turns out , the scattering lengths in region 1 are large enough to support two efimov trimers , while region 2 exhibits only a ground - state efimov trimer . [ [ observations - through - three - body - losses ] ] observations through three - body losses the experimentalists first reported the observation of a plateau of strong three - body losses in region 2 ( larger than the background losses by three orders of magntitude ) , delimited by a loss peak at around 130 gauss and a much softer peak around 500 gauss . they suggested that efimov physics could be behind these strong losses . using the zero - range theory and fitting the three - body parameter to the experimental data , theorists could indeed reproduce qualitatively the observed plateau @xcite and attributed it to the presence of a single efimov trimer appearing from the three - body scattering threshold at around 130 gauss and dissociating back into that threshold at 500 gauss @xcite . the fitted three - body parameter also made it possible to predict a loss peak in region 1 , at around 1160 gauss @xcite . such a peak was indeed observed very soon afterwards at lower temperatures by the group of k. ohara , but it was located at a smaller intensity of 900 gauss . the experimentalists identified this peak with the appearance of an excited efimov trimer , and showed that its location , along with those of the peaks previously observed in region 2 , were consistent with roughly the same three - body parameter . this was the first experimental report of an excited efimov trimer . [ [ observations - through - atom - dimer - losses ] ] observations through atom - dimer losses subsequent experiments in heidelberg and tokyo @xcite confirmed this interpretation by first preparing a gas of dimers of atoms in two different hyperfine states , by sweeping the magnetic field near one of the feshbach resonances . these large dimers could then relax into deeper states by inelastic collisions with the remaining atoms in the third hyperfine state . by measuring the relaxation rate as a function of the external magnetic fields , the experimentalists found two loss peaks around 600 gauss and 680 gauss . the zero - range theory @xcite showed that , qualitatively , these peaks correspond to a ground and excited efimov trimers dissociating in the atom - dimer scattering threshold . this confirmed the existence of the excited trimer previously observed at the three - body threshold . [ [ bound - state - spectroscopy-1 ] ] bound - state spectroscopy finally , both groups in heidelberg and tokyo were able to perform a radio - frequency spectroscopy of the excited trimer below the atom - dimer threshold @xcite . this was the first bound - state spectroscopy of an efimov trimer , i.e. the measurement of its binding energy below a scattering threshold rather than its effects at the scattering threshold . although the zero - range theory could unambigously interpret the features observed in lithium-6 , it could reproduce them only semi - quantitatively . to reproduce all features quantitatively the three - body parameter has to vary with energy @xcite by about 10% , and the inleasticity parameter @xmath257 describing recombination to deep dimers ( see section [ subsec:3bp - in - systems - with - loss ] ) has to be magnetic - field dependent @xcite or energy - dependent @xcite . to avoid these extra fitting assumptions , the work of @xcite incorporated two - body range corrections and the presence of deeper dimers via a two - channel model with gaussian separable potentials . while the overall agreement with experiment is good , the model could not reproduce the precise locations of all features with a single set of parameters . bo huang and co - workers @xcite recently used an updated two - body model of the feshbach resonances in lithium-6 @xcite to extract more accurately the three - body parameter from the data , using a three - body zero - range model . the three - body parameters obtained from regions 1 and 2 still differ by 5% , and deviate by 20% from the van der waals universal value observed in other species ( see section [ subsec : van - der - waals - universality ] ) . it would be worthwhile to revisit this problem with three - body models that properly incorporate van der waals physics and the more accurate description of the feshbach resonances of ref . @xcite . the dimensionality of space is crucial for the efimov effect to occur . for three identical bosons in @xmath194 dimensions , esben nielsen and co - workers @xcite have shown that the efimov effect can occur only when @xmath587 as a result , for integral dimensions , only @xmath588 leads to the efimov effect . in principle , the efimov effect may also happen for fractional dimensions in the allowed range , although this has not been demonstrated explicitly yet . according to nielsen s dimension criterion , there is no efimov physics in one and two dimensions @xcite . still , one- and two - dimensional three - body systems exhibit universal states when their interaction is tuned near the appearance of two - body bound states . however , because of the absence of efimov attraction , no three - body parameter needs introducing , and these universal states depend only the scattering length , as the universal two - body states . as a result , in the universal region , the energies of three - body and two - body states are proportional to each other , since they both scale with the scattering length , and there are no borromean states . moreover , because of the absence of long - range efimov attraction , the number of three - body bound states is finite . this is consistent with the theorem by s. a. vugalter and g. m. zhislin @xcite stating that few - body systems with finite - range interactions in one or two dimensions can only support a finite number of bound states . even though efimov physics does not occur , we briefly review the situation for these dimensions to contrast them with the efimov regime , and understand the connection with efimov physics in confined geometries . in one dimension , for a short - range pairwise interaction of range @xmath10 , the even - parity two - body wave function has the form @xmath589 for @xmath590 , where @xmath591 is the one - dimensional scattering length and @xmath17 is the relative wave number . the zero - range theory reproducing eq . ( [ eq : twobodywavefunction1d ] ) can be obtained by setting the following bethe - peierls boundary condition at @xmath592 , @xmath593{}\frac{1}{a_{\mbox{\tiny1d}}}\label{eq : bethepeierls1d}\ ] ] or by replacing the interaction by a contact potential @xmath594 of strength @xmath595 where and @xmath186 is the two - particle reduce mass . unlike in 3d , no renormalisation or regularisation of the delta function is needed here . in the one - dimensional zero - range theory , there is one two - body bound state of energy @xmath596 for positive @xmath591 ( attractive interactions ) and no bound state for negative @xmath591 ( repulsive interactions ) . for identical bosons in one dimensions , the problem admits analytical solutions @xcite . for @xmath597 , a system of @xmath5 particles admits exactly one @xmath5-body bound state of energy @xmath598 therefore the three - body bound state energy is @xmath599 in fact , there is also a virtual three - body bound state at zero energy ( @xmath600 ) @xcite , which can be seen by the fact that the particle - dimer scattering length is infinite . it can also be seen by considering particles with different masses , which can exhibit more than one bound state , and see that in the limit of equal masses , the second bound state vanishes at the three - body threshold . in this sense , the case of identical particles is a critical point for the appearance of the second three - body bound state . the more general situation of two identical bosonic particles @xmath601 of mass @xmath209 and one extra particle @xmath602 of mass @xmath9 was extensively studied by oleg kartavtsev and collaborators @xcite . if the coupling strength @xmath603 between two different particles is positive ( repulsive interaction ) then there is no three - body bound state , irrespective of the coupling @xmath604 between the identical particles . for negative @xmath603 ( attractive interaction between different particles ) , the results depend on the mass ratio @xmath395 and the interaction strength @xmath604 between the two identical particles . [ [ effect - of - the - mass - ratio ] ] effect of the mass ratio + + + + + + + + + + + + + + + + + + + + + + + + for mass ratios @xmath605 , there is at most one three - body bound state . larger mass ratios favor the existence of an increasingly larger number of three - body bound states . [ [ effect - of - the - interaction - between - identical - particles ] ] effect of the interaction between identical particles + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + when the identical particle interaction is more attractive than the attraction between different particles ( @xmath606 ) , there is a strongly bound aa dimer , and only one trimer with lower energy , for any mass ratio . for similar attractions @xmath607 and equal masses @xmath394 , we retrieve the case of three identical particles . the trimer energy is given by eq . ( [ eq:1dtrimerenergy ] ) , where @xmath608 . when @xmath604 is reduced to zero ( non - interacting identical particles ) , the trimer energy is reduced to @xmath609 as one would expect , repulsion between identical particles ( @xmath610 ) tends to further reduce the trimer energy and the number of trimers . in the limit of strong repulsion ( @xmath611 ) , there is no trimer for mass ratio @xmath605 . interestingly , this situation also describes the case of two non - interacting identical fermions and one extra particle , due to the one - to - one correspondence in one dimension between strongly interacting bosons and non - interacting fermions established by marvin d. girardeau @xcite . in two dimensions , the @xmath4-wave scattering length @xmath612 is always positive . when it is much larger than the range of the interaction , the interaction can be described by the following contact condition on the two - body wave function @xmath613 : @xmath614 which plays the role of the bethe - peierls condition eq . ( [ eq : bethepeierls ] ) for two dimensions . such zero - range model supports exactly one two - body bound state of energy @xmath615 given by @xmath616 where @xmath617 is euler s constant and @xmath186 is the reduced mass between the two particles . thus , unlike in 3d and 1d , there always is a two - body bound state in two dimensions . for identical bosons in two dimensions with zero - range interactions , one finds two three - body bound states , with energies @xcite : @xmath618 the four - body spectrum has also been calculated @xcite , and it is found that there are exactly two four - body bound states , with energies : @xmath619 the case of two non - interacting identical particles @xmath601 of mass @xmath209 , each interacting resonantly with one extra particle @xmath602 of mass @xmath9 was studied by ludovic pricoupenko and paolo pedri @xcite . the interaction between particles @xmath601 and @xmath602 is described by the scattering length @xmath612 , through the boundary condition eq . ( [ eq : bethepeierls2d ] ) . three - body bound states are characterised by a principal quantum number @xmath88 corresponding to excitations of the hyper - radial motion , and an internal angular momentum with a projection quantum number @xmath417 . when the two identical particles are bosons , the internal angular momentum has an even projection quantum number @xmath620 etc . the ground - state trimer exists for any mass ratio and has the quantum numbers @xmath21 . in the limit @xmath397 , its energy is given by @xmath621 and for @xmath394 , it is given by @xmath622 excited trimer states appear as the mass ratio is further increased , and their number presumably grows indefinitely . the first trimers appear at the following mass ratios : @xmath623 ( @xmath624 ) , @xmath625 ( @xmath624 ) , @xmath626 ( @xmath627 ) , @xmath628 ( @xmath629 ) , @xmath630 ( @xmath631 ) . when the two identical particles are fermions , the internal angular momentum has an odd projection quantum number @xmath632 etc . for a mass ratio @xmath395 smaller than @xmath633 , there is no three - body bound state . for larger mass ratios , there is a ground - state trimer with quantum numbers @xmath97 and @xmath406 . as in the bosonic case , the trimer energy and the number of trimer states increase as the mass ratio is increased . excited trimer states appear at the following mass ratios : @xmath634 ( @xmath635 ) , @xmath636 ( @xmath637 ) , @xmath638 ( @xmath639 ) , @xmath640 ( @xmath641 ) , @xmath642 ( @xmath643 ) . in ultra - cold atom experiments , it is possible to create lower - dimensional systems by confining the atoms in a narrow plane or tube by means of laser light . the technique is called _ optical lattice _ @xcite _ _ and consists in shining counter - propagating laser beams onto the atomic cloud . the interference of the beams results in a sinusoidal pattern of light , which creates a one - body potential for the atoms proportional to the light intensity through the stark effect . atoms are thus attracted to the nodes of the interference pattern , and repelled by the maxima for a blue - detuned light . with sufficiently strong lasers and appropriate layout of the beams , it is thus possible to confine the atoms in quasi-2d or quasi-1d geometries . this also gives the interesting possibility of going continuously from a three - dimensional to a lower - dimensional systems . from a theoretical point of view , since the efimov effect occurs only in three dimensions , it is natural to wonder how the infinity of efimov states continously transform into a finite number of trimer states at lower dimensions . this problem is reminiscent of the crossover that happens in systems with two heavy fermions and one light particle discussed in section [ subsec : kartavtsev - malykh - universal - trimers ] . in ref . @xcite , jesper levinsen , pietro massignan , and meera parish have looked theoretically into the case of confining efimov trimers in one direction , thus going from 3d to quasi-2d . they modelled the interaction by a three - dimensional zero - range interaction of scattering length @xmath26 , and the confinement by a harmonic trap of trapping frequency @xmath644 . a harmonic trap is a good approximation of a strongly confining optical lattice when the atoms reside at the bottom of a well in the lattice . it also offers the theoretical advantage of decoupling the centre of mass from the relative motion . jesper levinsen and co - workers obtained a version of the skorniakov and ter - martirosian equation for this problem , which they solved numerically . the two - body spectrum of such a system had already been investigated by dmitry petrov and georgy shlyapnikov @xcite in 2000 . the 3d two - body bound state for positive scattering length @xmath26 is unchanged as long as its extent , given by @xmath26 , is smaller than the confinement length @xmath645 . however , when @xmath646 , the dimer acquires a two - dimensional character . unlike the free space case , it continues to exist even for negative scattering length @xmath26 , where it becomes a low - energy quasi-2d dimer , whose energy is given by eq . ( [ eq:2ddimerenergy ] ) plus the zero - point energy @xmath647 , which constitutes the energy of the two - body threshold for particles whose motion along the confinement direction is in the ground - state of the harmonic trap . here , the two - dimensional scattering length is given by : @xmath648 where @xmath649 is a numerical constant and @xmath617 is euler s constant . thus , unlike the free space case , a dimer exists for any value of the 3d scattering length . similarly to the dimer case , it is clear that as soon as the system is confined , the trimers size can not extend beyond the confinement length @xmath650 . thus , among the infinity of efimov trimers , only those which can fit within the confinement region can exist . it would seem natural that the last two efimov trimers , which are the largest in size , and thus the most sensitive to confinement , would turn into 2d trimers in the limit of strong confinement . however , the calculations of levinsen and collaborators show that the situation is slightly more sophisticated . it is the ground - state and first - excited efimov states which continuously turn into quasi-2d trimers as their binding energy is lowered by tuning the ( 3d ) scattering length to negative values . these states thus never dissociate into the three - body threshold , unlike in free three - dimensional space ( the @xmath254 point ) . this happens , however , through avoided crossings between the 3d efimov trimers and 2d universal trimers , as shown in fig . [ fig : quasi2d ] . the other trimer states are pushed up by these avoided crossings . for strong enough confinement , they do not exist all , and there are just two trimers . for weaker confinement , they appear from the dissociation threshold at values of the scattering length that get closer to the value of @xmath254 in 3d as the confinement is reduced . in the limit of weak confinement , one retrieves the free - space efimov spectrum with many trimers . the authors of ref . @xcite conjecture that a similar picture should hold for systems confined in two directions , going from 3d to quasi-1d . similar crossover behavior may also be expected for the mass - imbalanced two - component fermi systems discussed in sections 6.2.2 and 6.2.5 @xcite . .[tab : mixed - dimensions - systems]various systems of two particles a of mass @xmath651 resontantly interacting with one particle b of mass @xmath652 in mixed dimensions , which are expected to exhibit the efimov effect . these systems are constructed by requiring that at least two two - body subsystems correspond to a case listed in fig . [ fig : relative - motion - mixed - dimensions ] . the first case in the top left corner is the familiar situation where all particles move in three - dimensional space . while the efimov effect always occurs if the two particles a are identical bosons or distinguishable particles , it may depend on the mass ratio @xmath653 if the two particles a are identical ( polarised ) fermions . for each case , it is indicated whether the efimov effect occurs ( @xmath654 ) or not ( ) , or the mass ratio @xmath653 beyond which the efimov effect occurs . in the case of bilayer ( 3rd column ) and biwire ( 5th column ) geometries , the two particles are by construction distinguishable , and their statistics does not matter . [ cols="^,^,^,^,^,^ " , ] although the efimov effect is restricted to particles in three dimensions , yusuke nishida and shina tan have found that efimov physics can extend to particles moving in subspaces of different dimensions , a situation called _ mixed dimensions _ @xcite that can be realised by confining only certain particles instead of all three particles . in an article entitled `` liberating efimov physics from three dimensions '' @xcite , they explained the general arguments to identify such favourable situations . first of all , yusuke nishida and shina tan gave an intuitive interpretation of the absence of efimov physics in other dimensions than @xmath655 . they argued that a necessary condition for efimov physics is that the dimensionless two - body wave function at unitarity exhibits a scale - invariant attraction . at short separations @xmath3 , the two - body wave function at unitarity is the singular solution of the laplace equation . in @xmath656-dimensions , it is thus @xmath657 for @xmath658 , this wave function can not be normalised due to the divergence at the origin @xmath42 , which means that unitarity does not exist in the zero - range limit . physically , this implies that particles form tight dimers at separations on the order of the range @xmath10 of the interaction @xcite . this tight binding prevents the binding of a third particle at large separations , and thus the efimov effect . on the other hand , for @xmath659 , the unitarity wave function eq . ( [ eq : unitary - wave - function - in - d - dimensions ] ) is constant near the origin ( this can also be seen from eq . ( [ eq : bethepeierls2d ] ) : when @xmath660 , the wave function is nearly constant around @xmath661 ) . this implies that the two particles are effectively non - interacting , which prevents any binding of the particles - indeed , the two - body bound state disappears for @xmath662 . for @xmath663 , the unitarity wave function eq . ( [ eq : unitary - wave - function - in - d - dimensions ] ) vanishes at the origin as @xmath3 ( this can also be seen from eq . ( [ eq : twobodywavefunction1d ] ) when @xmath664 ) , which corresponds to a hardcore repulsion , equivalent to the pauli repulsion ( node in the wave function ) between non - interacting fermions @xcite . this repulsion also prevents particles from binding . therefore , only the case @xmath655 presents a unitary two - body wave function that is scale - invariant and exhibits an attractive effect . in a second step , nishida and tan point out that what matters in general is not the dimension @xmath655 of space itself , but the dimensionality of the relative motion . for two particles moving in the same space , the dimensionality of the relative motion is equal to that of the space , because the locations of the two particles are described by two @xmath656-vectors , and after elimination of the centre of mass which is also described by a @xmath656-vector , there remain exactly @xmath656 coordinates . however , the situation is different for particles moving in subspaces of different dimensions @xmath665 . the dimensionality is given by the sum of the dimensions of the subspaces in which each particle moves , minus the dimension of the intersection of all sub - spaces , in which the centre - of - mass coordinates can be separated from the relative motion . figure [ fig : relative - motion - mixed - dimensions ] shows all the possible combinations of scattering particles in mixed dimensions such that the relative motion is described by exactly three coordinates . in all cases , the equation of relative motion is therefore the same laplace equation , assuming that the particles interact through an @xmath5-particle contact interaction specified at unitarity by the scale - invariant boundary condition : @xmath666 hence , by analogy with the purely three - dimensional case , one can expect that the addition of an extra particle in these systems will lead the efimov effect as well . according to yusuke nishida and shina tan , this is indeed true , although they have postponed the actual demonstration in the general case to a future publication . nevertheless , they give results for several cases involving two identical particles a and a particle b. the cases are shown in table [ tab : mixed - dimensions - systems ] . for each case , nishida and tan have numerically calculated the scaling strength @xmath667 as a function of the mass ratio @xmath653 . as in the pure 3d case ( see section [ subsec : observations - in - nuclear - multi - component ] ) , @xmath667 monotonically increases with the mass ratio , and in the case of fermions cancels at a critical mass ratio , below which the efimov effect does not occur . the critical mass ratios are given in table [ tab : mixed - dimensions - systems ] . interestingly , the strength @xmath667 also increases when the dimension of space for one or two particles is reduced . thus confining one or two particles into lower - dimensional spaces makes it easier to observe efimov states . in particular , in the case of particles including identical fermions for which the mass ratio is not enough to yield efimov attraction , the efimov effect may occur by confining one or two particles @xcite . yusuke nishida and shina tan call this effect the _ confinement - induced efimov effect . _ another remarkable situation is the case of particles separated in disjoint subspaces , such as parallel layers @xcite or wires , as shown in the third and fifth column of table [ tab : mixed - dimensions - systems ] . of course , for a two - body contact interaction to take place , these disjoint subspaces must intersect the space of the third particle . this way , both particles can interact with the third particle , and thus the third particle can mediate interaction between the two particles . yet , the two particles are always spatially separated and can not come in contact . this has two major consequences . first , the statistics of the particles does not matter any more , because they can be regarded as distinguishable particles , being with certainty in different locations . thus , the pauli repulsion between identical fermions that limits the efimov effect to sufficiently large mass ratios , does not play a role any more . in such mixed - dimensional settings , fermions always exhibit the efimov effect . second , even though two of the three particles can come in contact , the three particles can never come closer than the separation between the two disjoint subspaces . in systems undergoing loss by three - recombination ( such as ultra - cold atoms ) , this fact can completely suppress the loss , by preventing the three particles from coming all three at distances where recombination occurs . it is thus a clever way to realise efimov states that are inherently stable , unlike their counterpart in free space . since the separation @xmath194 between the two subspaces constitutes the smallest distance that the three particles can come to , it is the length scale that breaks the discrete scale invariance and determines the ground - state energy and three - body parameter of the trimers . in particular , at unitarity , @xmath668 @xmath669 the constants @xmath670 and @xmath74 have been calculated numerically by yusuke nishida and shina tan for both the bilayer - free ( 2d@xmath6712d@xmath6713d ) and biwire - free ( 1d@xmath6711d@xmath6713d ) geometries , for the two mass ratios 40/6 and 6/40 . the strength @xmath667 is the same as for the single - layer ( 2d@xmath6723d ) and single - wire ( 1d@xmath6723d ) geometries , because in the limit of weakly bound efimov trimers , the separation between the layers or wires is vanishly small compared with the size of the trimers , and can be regarded as a single layer or wire in the calculation of @xmath128 . explicit calculations of the trimer energies as a function of the scattering length for bilayer - free and biwire - free geometries were performed by tao tin , peng zhang , and wei zhang @xcite , using the born - oppenheimer approximation . the authors also calculated the ground - state tetramer energy for the triwire - free geometry . they found that the trimers and tetramers exist in a range of negative and positive scattering lengths , as in the 3d case , and the binding energy reaches a maximum when the scattering length is close to the separation between the layers or wires . the mixed dimension setting has been studied experimentally in only one group so far . the group of massimo inguscio and francesco minardi in florence have realised a 2d-3d mixed - dimensional system by confining potassium atoms in the 2d layers of an optical lattice , and let them interact with rubidium atoms @xcite . the interactions between the two species can be changed by a magnetic feshbach resonance . this way , the researchers could explore the variation of the effective mix - dimensional scattering length , and observed through recombination loss spectroscopy the location of mix - dimensional two - body resonances that are required for efimov physics to set in @xcite . however , efimov features predicted in the preceding sections have not been revealed yet . as explained in section [ subsec : efimov - theory ] , the three - body parameter is a parameter that needs to be introduced to regularise the zero - range theory of three particles . this parameter can be introduced in several ways depending on the formalism used : a three - body short - range boundary condition or a three - body short - range phase @xcite , a two- or three - body momentum cut - off @xcite , or a three - body contact interaction @xcite . therefore , there is not a single formal definition of this parameter , and it can take the form of a length or an energy , etc . in any case , it is associated with three - body observables , such as the trimer energy of the particle - dimer scattering length . when the three - body parameter is changed , the value of these observables is rescaled accordingly . in the efimov spectrum as a function of inverse scattering length shown in fig . [ fig : efimovplot ] , this corresponds to a radial rescaling of the curves with respect to the accumulation point at the centre . one often takes one of the following observables ( shown in fig . [ fig : efimovplot ] ) as convenient references to characterise the three - body parameter : 1 . the binding wave number @xmath126 associated with the trimer energy @xmath673 at unitarity ( the scattering length @xmath28).[enu : the - binding - wave - number ] 2 . the dissociation scattering length @xmath254 at which the trimer energy vanishes in the three - body scattering threshold.[enu : the - dissociation - scattering - length ] 3 . the scattering length @xmath270 at which the three - body recombination rate has a minimum ( for lossy systems).[enu : the - scattering - length - a+ ] 4 . the scattering length @xmath269 at which the trimer energy vanishes at the particle + dimer scattering threshold.[enu : the - scattering - length - astar ] these observables are related to each other by universal relations in the zero - range theory . namely , for identical bosons @xcite , @xmath674 @xmath675 @xmath676 note that because of the discrete scale invariance , these quantities are defined up to a factor @xmath677 , with @xmath678 . in other words , @xmath126 and @xmath679 represent the same three - body parameter . the zero - range theory is of course an idealisation , since in reality interactions do have a finite ( i.e. non - zero ) range . in reality , the zero - range theory is applicable in the universal window of very large scattering length and very small energy . in this window , the above observables can be used to determine the three - body parameter . in this sense , the three - body parameter , although originally a parameter of the zero - range theory , can also be determined from finite - range calculations or experimental data provided they can access the universal window of highly - excited states or low - energy scattering . in general , it might be better to talk about the _ three - body phase _ , as in eq . ( [ eq : threebodyphase ] ) , which is a physical quantity independent of the model , and reserve the expression _ three - body parameter _ for the parameter of zero - range theories that fixes that phase . nevertheless , the expression three - body parameter is commonly used in the sense of three - body phase , even in experimental contexts . in a realistic system , it is often experimentally or computationally difficult to access the universal window corresponding to highly excited trimers . from the first few trimers of the efimov series of a realistic ( finite - range ) system , one may extract quantities @xmath680 , @xmath681 , @xmath682 , @xmath683 for each trimer @xmath684 , and consider them as approximate measures of the three - body parameter . strictly speaking , only in the large @xmath685 limit do they tend to values representing the three - body parameter ( up to a factor @xmath677 ) , and the universal relations ( [ eq : universal_relation_aminus_kappastar]-[eq : universal_relation_astar_kappastar ] ) hold only approximately for @xmath680 , @xmath681 , @xmath682 , @xmath683 with small @xmath685 . on the other hand , the finite - range system quantities @xmath680 , @xmath681 , @xmath682 , @xmath683 can help remove the ambiguity over the factor @xmath677 in the definition of @xmath686 . for instance , one can restrict the definition of @xmath126 such that @xmath687 corresponds approximately to the binding wave number @xmath680 of the @xmath685-th efimov state . however , this definition still depends on what is considered to be the first efimov state . for simplicity , and in view of the recent definitions of `` efimov state '' ( see sect . [ subsec : what - is - an - efimov - state ] ) , we will always label the ground - state trimer as the first efimov state @xmath688 . when the efimov effect occurs in systems supporting several two - body bound states , the efimov states are trimer resonances that can decay by recombining into a lower two - body bound state scattering off a third particle . in the zero - range theory , such lower two - body bound states are not present , yet eric braaten , hans - werner hammer , and masaoki kusunoki have shown that their combined effect can be described in the zero - range theory by introducing an inelasiticity parameter @xmath689 @xcite . physically , @xmath690 represents the probability of an incoming hyper - radial flow to be reflected back to large hyper - radii , the rest being lost ay short distance by recombination . formally , this amounts to giving the three - body parameter a complex value @xmath691 . this makes the energy of the efimov states complex , @xmath692 , where the imaginary part corresponds to the energy width associated with their finite lifetime . in the limit of small @xmath257 , one finds @xmath693 . a natural question that arises is what in the microscopic details of the finite - range interactions of real systems determines the three - body parameter . at first glance , two different views can be proposed : [ [ the - three - body - parameter - is - roughly - determined - by - the - range - of - interaction ] ] 1 . the three - body parameter is roughly determined by the range of interaction + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + the first view is that the scale of the three - body parameter is roughly determined by the range @xmath10 of the interaction , i.e. the length beyond which the interaction can be taken as null or negligible . indeed , this range constitutes the length scale below which the zero - range theory ceases to be valid . it is when the three particles approach this range that the three - body boundary condition determining the three - body parameter is set . it is therefore a natural guess that the resulting three - body parameter , expressed as a length scale , is on the order of this range . this idea is supported by the early work of llewellyn h. thomas @xcite , although the efimov effect was not known at the time . in this work , it was found that the ground state of the three - body problem depends on the range of the interaction . namely , its energy becomes deeper as the range of interaction is reduced ; in the limit of zero - range interaction , the energy goes to minus infinity , in other words the spectrum is unbound from below , a phenomenon later known as the thomas collapse . llewellyn thomas used this finding to estimate the triton binding energy from the range of nuclear forces . [ [ the - three - body - parameter - can - take - any - value ] ] 2 . the three - body parameter can take any value + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + the second view is that the three - body parameter is a three - body boundary condition for the free wave , in the same way as the two - body scattering length being a two - body boundary condition for the free wave - see the bethe - peierls condition eq . ( [ eq : bethepeierls ] ) . it is known that the scattering length is in general difficult to predict from the details of the two - body interaction . for a purely repulsive interaction , the scattering length is on the order of the interaction range , but for an attractive interaction , it can be very different . although on average ( over many interaction potentials ) the scattering length is on the order of the interaction range , it may be much larger as well as positive or negative @xcite , and one is often required to solve the two - body schrdinger equation to obtain the value of the scattering length for a given interaction potential . especially for interaction potentials with a deep well , the scattering wave function accumulates a large phase inside the well , and a minute change in the short - range details of the potential can completely change the value of the scattering length . by analogy , in the three - body problem at unitarity , one can view the three - body body parameter as the result of the short - range boundary condition for the hyper - radial problem with the efimov attractive potential eq . ( [ eq : efimovattraction ] ) . the short - range boundary condition arises from the complicated three - body dynamics at short range where all hyper - angular channels are coupled . to get some insight , though , one can model this dynamics by an effective short - range hyper - radial potential . as in the two - body case , if this short - range potential is purely repulsive ( such as a hard wall at @xmath694 ) the three - body parameter is set by the range of the repulsion . on the other hand , if the short - range potential is attractive , it can take very different values . for instance , if an attractive @xmath695 potential well ( van der waals type ) is used as a short - range boundary condition , one finds that the three - body parameter can take any value with substantial probability - see the left panel of fig . [ fig : three - body - phase ] . from these simple calculations , one concludes that in general the three - body parameter , like the two - body scattering lengh , can take on any value and is sensitive to the short - range details of the interaction . + the above two views 1 and 2 can be conciled by saying that in general the three - body parameter can take any value depending on the short - range details of the interaction , but on average ( over many interaction potentials ) it scales with the range of the interaction . while it is true that the three - body parameter may in general take any value , there are some notable cases presented in the following sections for which it is simply related to a length scale of the two - body interaction . there have been many calculations of the three - body problem with finite - range interactions near unitarity , from which one can extract the efimov three - body parameter , at least approximately . for example , the work of moszkowski and co - workers @xcite has investigated , for many shapes of two - body potential , the strength required to bind three particles with respect to the strength required to bind two particles - such a calculation is equivalent to the determination of @xmath696 , which is an approximate measure of the three - body parameter . their calculation indicates that the strength ratio could vary from 2/3 to 1 , although it is often close to 0.8 , which suggests a nominal value for the three - body parameter , supporting view 1 . later , motivated by the experimental development of efimov physics in ultra - cold atomic gases , jos dincao and co - workers @xcite investigated more specifically the variation of the three - body parameter from one two - body resonance to another , as the strength of the same two - body potential is increased ( the efimov states in this case are resonances -see the end of section [ subsec : what - is - an - efimov - state ] ) . they concluded that the value of the three - body parameter changes significantly , and is further modified by the presence of a three - body force , supporting view 2 . until efimov states could be observed in ultra - cold atomic gases , there was no experimental data directly related to the three - body parameter . from 2006 onwards , quantities such as @xmath126 , @xmath254 , @xmath270 , and @xmath269 could be measured around different resonances in various atomic species ( see section [ subsec : ultracold - atoms ] ) , at least for the ground efimov state and in some cases the first excited efimov state , thus providing some experimental estimate of the three - body parameter . surprisingly , the obtained values @xcite were not randomly distributed over an efimov log - period @xmath697 $ ] , but instead showed a strong correlation with the range of the atomic interaction , taken to be the van der waals length that accounts for the finite size of atoms and molecules in the equation of state of gases . ] , @xmath698 associated with the van der waals tail @xmath699 of the interaction betwen two neutral atoms of reduced mass @xmath186 @xcite . the correlation of experimental results for @xmath254 for identical bosons is shown in fig . [ fig : van - der - waals - universality ] . it gives on average : @xmath700 this average value is obtained from values of @xmath701 for the ground - state ( @xmath97 ) and first - excited ( @xmath702 ) efimov states . the stated uncertainty is two standard deviations of the data ; all experimental data fall into this range . the values obtained from the ground - state resonances are expected to deviate ( by up to 25% ) from the exact three - body parameter . these values alone give : @xmath703 the first - excited - state resonances are expected to be closer to the exact three - body parameter ( within a few percent ) . there are currently two experimental values for such resonances . one is for a resonance in cesium-133 at a magnetic field around 800 g @xcite , @xmath704 the other comes from a resonance at around 900 g in lithium-6 experiments @xcite , which involve three distinguishable fermions behaving like identical bosons . a recent and thorough analysis of the data @xcite , including thermal corrections , gives the value @xmath705 all these results indicate that within an error of 20% , the three - body parameter is universally determined by the van der waals length , with @xmath706 . van der waals universality of the three - body parameter observed in ultra - cold atomic gases for cesium-133 @xcite , rubidium-85 @xcite , potassium-39 @xcite , lithium-7 @xcite , and metastable helium-4 @xcite . for potassium-39 , the data corresponds to a point originally assigned to a four - body resonance @xcite . also shown are the results @xcite of lithium-6 experiments @xcite , which involve three distinguishable fermions behaving like identical bosons , except that they have three different scattering lengths . the value of @xmath254 for these experiments is estimated by the formula @xmath701 . results for @xmath97 ( ground state ) are shown by crosses , whereas results for @xmath702 ( excited state ) are shown by squares . a linear fit of the results is plotted , along with a shaded area indicating two standard deviations . ] this remarkable experimental finding triggered theoretical activity to understand its origin . the first proposed explanation @xcite invoked quantum reflection of the three - body wave function in the region where atoms undergo van der waals attraction . the argument supporting this idea is based on the calculation of the three - body phase from a hyper - radial potential which consists of an efimov attraction at large distance and a deep square well potential at short distance ( approximating the effects of the two - body van der waals attraction ) . it is represented in the right panel of fig . [ fig : three - body - phase ] . for deep wells , the three - body phase appears to stabilise around a well - defined value , close to @xmath707 . however , the stability of the three - body phase turns out to be a peculiarity of the square well approximation . as we discussed previously , when the square well in the hyper - radius potential is replaced by a van der waals attraction , the three - body phase can take different values with significant probability - see the left panel of fig . [ fig : three - body - phase ] . nevertheless , the idea of quantum reflection looked compelling and prompted theorists to check thoroughly the physics of three particles interacting via deeply attractive van der waals potentials . the work of jia wang and co - workers @xcite presented the first exact calculation , using the adiabatic hyper - spherical representation . in this method , the three - body wave function is expressed as a linear combination of products of hyper - radial and hyper - angular wave functions @xmath708 , where the hyper - radius @xmath72 characterises the size of the three - body system and is defined . here , we use a definition that is consistent with the one used in section [ subsec : efimov - theory ] - see eq . ( [ eq : hyper - radius ] ) . ] as @xmath709 , and @xmath710 denotes the set of remaining coordinates describing the geometry of the three - body system , which are called hyper - angles . note that this form becomes separable only for the zero - range interaction at unitarity , see eq . ( [ eq : separablesolution ] ) . for finite - range interactions such as the van der waals type , the hyper - radius @xmath72 is coupled to the hyper - angles @xmath710 at short distance . hyper - angular wave functions @xmath711 are thus calculated to obtain hyper - radial potentials @xmath712 , as well as coupling terms @xmath713 , which lead to a set of coupled equations for the hyper - radial motion : @xmath714 where @xmath72 is expressed in units of van der waals length @xmath715 and the potentials @xmath716 , @xmath717 is expressed in units of van der waals energy @xmath718 . these hyper - radial equations uncouple at large hyper - radius , and one of them features a hyper - radial potential @xmath719 that asymptotes to the efimov attraction @xmath720 of eq . ( [ eq : efimovattraction ] ) . solving the coupled equations ( [ eq : coupledhyperradialequations ] ) for various two - body interactions with a van der waals tail , jia wang and co - workers found that the three - body parameter is essentially determined by the van der waals tail and relatively insensitive to other details . in the limit of deep van der waals interactions , they found : @xmath721 @xmath722 which is close to ultra - cold atom observations given in fig [ fig : van - der - waals - universality ] and eq . ( [ eq : experimentalvdwaminus0 ] ) . for shallower potentials for which the van der waals character is less pronounced , they found slightly larger values of @xmath723 and @xmath696 . these values were recently confirmed in refs . @xcite for shallow van der waals potentials with a repulsive core and supporting only one two - body bound state , giving : @xmath724 for all van der waals potentials investigated so far , deep or shallow , with or without a repulsive core , the values of @xmath725 are comprised in the range @xmath726 $ ] , i.e. @xmath727 . this theoretical value is often cited in the literature , as it agrees well with the experimental value of eq . ( [ eq : experimentalvdwaminus0 ] ) . however it is more relevant to shallow potentials , and the value in eq . ( [ eq : aminusforvdw ] ) should be taken as the universal value relevant to interactions dominated by their van der waals tail . the more important deviation between this value and the experimental value of eq . ( [ eq : experimentalvdwaminus0 ] ) suggests that other physics beyond the van der waals universality may contribute to the three - body parameter of atoms close to a broad magnetic feshbach resonance @xcite . [ [ three - body - repulsionparthree - body - repulsion ] ] three - body repulsion[par : three - body - repulsion ] + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + jia wang and co - workers looked for a simple reason for this universality in their calculated hyper - radial potentials . they found that the potential @xmath719 exhibits a steep repulsive barrier at a hyper - radius @xmath728 , instead of a strong attraction as one would navely expect from the van der waals attraction . furthermore , they found that this repulsive barrier is always present , _ _ irrespective of the presence or absence of a repulsive core _ _ in the two - body potential , and in the limit of deeply attractive potentials has a seemingly universal form that depends only on the van der waals tail of the potential - see the grey curves in the top panel of fig . [ fig : three - body - repulsion ] . this observation alone can not explain their results , because the potential @xmath719 is strongly coupled to other channels in the region of the repulsive barrier . solving the coupled equations , jia wang and co - workers found that this repulsive barrier is actually enhanced by the hyper - radial couplings @xmath729 and effectively suppresses the probability of finding the three particles within a hyper - radius @xmath730 . the authors confirmed that imposing such a steep barrier by hand in the potential @xmath719 alone sets the three - body phase to a value in good agreement with their exact results eq . ( [ eq : kappaforvdw]-[eq : aminusforvdw ] ) . the repulsive barrier also explains why the results do not depend much on the interatomic three - body forces , such as the axilrod - teller potential @xcite : the repulsive barrier prevents the three atoms from coming to the short distances where they would experience the three - body force . the three - body repulsive barrier was confirmed in a different manner by emiko hiyama and masayasu kamimura @xcite from exact three - body calculations with various helium potentials . using the gaussian expansion method to solve the three - body problem , they obtained the energies @xmath120 and the three - body wave functions of trimers at unitarity . integrating the squared wave function over hyper - angles to obtain the integrated hyper - radial density @xmath731 gives the effective hyper - radial wave function @xmath732 . this can be converted into the effective hyper - radial potential @xmath733 assuming that @xmath734 satisfies a single schrdinger equation akin to eq . ( [ eq : coupledhyperradialequations ] ) . hiyama and kamimura found that for all the helium pairwise potentials , both the ground and first - excited trimers give the same potential @xmath735 in the van der waals region and it exhibits the universal repulsive barrier - see the green curve in the top panel of fig . [ fig : three - body - repulsion ] . this results in @xmath736 for all the helium potentials , in agreement with the calculations of refs . @xcite for shallow lennard - jones potentials . the calculations of refs . @xcite thus indicate that the origin of the van der waals universality of the three - body parameter is a _ three - body repulsion _ rather than quantum reflection . jia wang and co - workers noted that this repulsion originates from the suppression of probability to find two atoms at short separation . this suppression of probability is due , as in classical mechanics , to the acceleration of the relative motion by the attractive potential , which makes the two atoms spend little time at short separation . this suppression squeezes the three - body wave function , which results in an increase of kinetic energy that is responsible for the repulsive barrier . [ [ connection - with - two - body - physicsparconnection - with - two - body - physics ] ] connection with two - body physics[par : connection - with - two - body - physics ] + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + the work of ref . @xcite confirmed the interpretation of jia wang and co - workers @xcite , and showed that this increase of kinetic energy is physically related to a deformation of the three - body system from its configuration at large separations to shorter hyper - radii . at large hyper - radius , the three - body configuration is independent of the hyper - radius , and distributed according to the efimov hyper - angular wave function , @xmath737 where @xmath738 is given by eq . ( [ eq : hyperangularsolution ] ) and @xmath739 denote the hyper - angles @xmath74 for the three possible jacobi sets of coordinates eq . ( [ eq : jacobi - r]-[eq : jacobi - rho ] ) . as mentioned in section [ subsec : efimovstructure ] , the most probable configurations have an elongated - triangle geometry : two particles are close and one is farther away . however , at hyper - radii on the order of the van der waals length , the suppression of two - body probability forces the system to adopt an equilateral configuration - see the bottom panel of fig . [ fig : three - body - repulsion ] . this change of configuration can be seen in the hyper - radius dependence of the hyper - angular wave function @xmath740 , and the kinetic energy associated with this deformation is described by the non - adiabatic term @xmath741 contained in @xmath719 . as the three - body system probes shorter hyper - radii , the deformational energy due to the two - body suppression arises as a repulsive barrier in @xmath719 . to support this interpretation , the authors of ref . @xcite presented two models built on the van der waals two - body suppression , that lead to the universal three - body repulsion . the first model consists in making the following ansatz for the hyper - angular wave function , @xmath742 i.e. the hyper - angular wavefunction @xmath743 from the zero - range theory is multiplied by a two - body correlation function @xmath744 for all three pairs . this two - body correlation is taken to be the two - body radial wave function @xmath745 at zero - energy for a potential at unitarity with a van der waals tail . this pair correlation ansatz describes the suppression of two - body probability in a simple fashion , and can be used to calculate the hyper - radial potential @xmath719 . two - body radial probability density @xmath746 at unitarity ( @xmath747 ) as a function of interparticle separation @xmath3 , for a deep van der waals potential ( black , obtained from eq . ( [ eq : vanderwaalstwobodywavefunction ] ) ) and for a shallow van der waals potential with a repulsive core ( red ) . the corresponding potentials are shown in dashed curves . in both cases , the probability density is suppressed for @xmath748 . in the first case , this is due the acceleration in the attractive van der waals potential . in the second case , this is due to the repulsive core . the density profile is nearly the same for @xmath749 since both potentials have the van der waals form in this region . ] the two - body radial wave function @xmath750 is known to have a universal form in the van der waals region : @xmath751 where @xmath752 and @xmath753 and @xmath754 denote the gamma and bessel functions . at shorter distances @xmath755 , @xmath750 has a potential - dependent form and vanishes at @xmath42 . the number of nodes in @xmath750 corresponds to the number of @xmath4-wave two - body bound states supported by the potential . the probability density @xmath746 is plotted as a solid black curve in fig . [ fig : two - body - radial - density ] . the authors of ref . @xcite found that the resulting hyper - radial potential @xmath719 exhibits a repulsive barrier similar to that of ref . @xcite - see the blue curves in the top panel of fig . [ fig : three - body - repulsion ] . the barrier is due to the large value of the non - adiabatic term @xmath756 of eq . ( [ eq : nonadiabaticdiagonalterm ] ) , confirming the deformation scenario . the repulsive barrier does not depend much on the short - range form of the potential nor its number of bound states , as long as the two - body probability is sufficiently suppressed at short - distance , i.e. @xmath750 has most of its amplitude in the van der waals region where it has the universal form eq . ( [ eq : vanderwaalstwobodywavefunction ] ) . this occurs for most physical potentials , which feature either a strongly repulsive core or a deep well that reduces the short - distance probability - see fig . [ fig : two - body - radial - density ] . in the second model of ref . @xcite , the two - body suppression is introduced through a separable representation of two - body van der waals potentials . any local potential @xmath757 can be represented as a superposition of non - local separable potentials , a representation introduced by ernst , shakin and thaler ( est ) @xcite . truncating this representation to a single separable potential @xmath758 gives an approximation of the original potential @xmath757 that reproduces one of its eigenstates @xmath759 exactly at a chosen energy , and other eigenstates approximately around that energy . the separable potential @xmath758 is explicitly constructed from that eigenstate as @xmath760 from this expression , one can easily check that the action of @xmath758 and @xmath757 onto @xmath759 is the same . choosing again @xmath759 to be the zero - energy scattering state , the resulting separable potential reproduces that state exactly by construction , and therefore the two - body suppression at low energy . solving the three - body problem with this separable potential ( see appendix for details ) , constructed from a @xmath750 that is dominated by the van der waals form eq . ( [ eq : vanderwaalstwobodywavefunction ] ) , gives a three - body parameter that is consistent with the results of jia wang and co - workers @xcite . in the limit of a deep van der waals potential @xmath757 , i.e. when @xmath750 tends to the van der waals form eq . ( [ eq : vanderwaalstwobodywavefunction ] ) , the authors find @xmath761 @xmath762 in fair agreement with eqs . ( [ eq : kappaforvdw]-[eq : aminusforvdw ] ) . furthermore , the authors integrated the obtained three - body probability density over the hyper - angles to obtain a hyper - radial wave function , and converted that wave function into an effective hyper - radial potential through eq . ( [ eq : effectivehyperradialpotential ] ) . the resulting potential is shown by the red curves in the top panel of fig . [ fig : three - body - repulsion ] and compares well with the potentials of ref . @xcite and @xcite . these results show that the van der waals universality of the three - body parameter is a consequence of the van der waals two - body universality given by eq . ( [ eq : vanderwaalstwobodywavefunction ] ) . the van der waals universality extends to systems of different particles , such as heteronuclear atomic systems . the physics is richer because the particles may have different masses , different quantum statistics , and the interactions may have different van der waals lengths in addition to different scattering lengths . the case of two identical bosons @xmath601 of mass @xmath651 and one particle @xmath602 of mass @xmath763 was theoretically studied by yujun wang and co - workers in ref . @xcite using 6 - 12 lennard - jones potentials @xcite @xmath764 and @xmath765 . in this case , as discussed in section [ sec : multi - component - systems ] , there are two scattering lengths @xmath766 and @xmath767 and two limits for which the efimov effect occurs : @xmath768 with @xmath766 finite , and @xmath769 . accordingly , for these two efimov regimes , there are two geometric scaling strengths , respectively @xmath128 and @xmath770 , and two three - body parameters , respectively @xmath124 and @xmath771 . the authors of ref . @xcite found that , for a given mass ratio @xmath772 between @xmath601 and @xmath602 , these three - body parameters are determined solely from the van der waals lengths @xmath773 and @xmath774 ( as well as @xmath766 for the first efimov regime ) , and do not depend upon other short - range details , as in the case of three identical bosons . nevertheless , they found that this van der waals universality is explained differently for the efimov - favoured limit ( the limit of large mass ratio @xmath772 , i.e. two heavy bosons and one light particle ) and the efimov - unfavoured limit ( the limit of small mass ratio @xmath772 , i.e. two light bosons and one heavy particle ) . in the efimov - unfavoured limit , the two efimov regimes are well separated . the first efimov regime corresponds to a family of bound states in a hyper - radial potential ( that asymptotes to the dissociation threshold @xmath775 for @xmath776 ) , whereas the second efimov regime corresponds to a family of bound states in another hyper - radial potential ( that asymptotes to the dissociation threshold @xmath777 for @xmath778 ) . the authors of ref . @xcite found that the hyper - radial potential for the first efimov regime has a universal form for a fixed @xmath773 and @xmath774 when it is expressed in units of @xmath766 , while the hyper - radial potential for the second efimov regime has a universal form for a fixed @xmath773 and @xmath774 , which is independent of @xmath766 . this form exhibits the efimov attraction at large distance , and a short - range repulsion that is similar to that of three identical bosons . this three - body repulsion presumably follows from the same two - body induced deformation mechanism explained in the previous section . in the efimov - favoured limit , on the other hand , the hyper - radial potential picture becomes inadequate to understand the three - body parameter : the repulsive barrier in the potential featuring the efimov attraction goes to shorter and shorter distances and becomes irrelevant , while the couplings to other channels become increasingly strong . the authors of ref . @xcite found that the born - oppenheimer picture is better suited for this situation . this picture consists in considering the two heavy bosons as slow , and take their relative coordinate @xmath3 as the adiabatic variable instead of the hyper - radius @xmath72 . as the two bosons slowly move , the light particle is assumed to adiabatically follow a wave function @xmath779 that is calculated at each separation @xmath3 of the two bosons . the three - body wave function is therefore @xmath780 the determination of @xmath779 yields eigenstates @xmath781 and eigenvalues @xmath782 . one of these eigenvalues corresponds to a potential @xmath783 exhibiting the efimov attraction at large @xmath3 ( when @xmath784 ) . the relative wave function @xmath785 for the two bosons is then simply given by the following schrdinger equation : @xmath786 note that in this efimov - favoured limit , the two efimov regimes are nearly the same ( @xmath787 ) , and appear in the born - oppenheimer approximation as a single efimov effect described by a single channel ( corresponding to the potential @xmath788 ) and a single three - body parameter approximating the two three - body parameters . this three - body parameter is then determined by the form of the potential @xmath789 . according to ref . @xcite , @xmath783 turns out to be negligible in the short - range region , and therefore the short - range phase of @xmath785 is set by the van der waals potential @xmath764 only . as is known from the theory of van der waals potentials @xcite , that phase depends only on the van der waals tail of this potential and its scattering length @xmath766 . as a result , the three - body parameter depends only on the van der waals length @xmath773 and the scattering length @xmath766 . if @xmath790 , it may also depend on @xmath774 since the potential @xmath788 may depend on the van der waals tail of @xmath765 at intermediate distances . the conclusion is therefore the same as for the efimov - unfavoured limit : the three - body parameters depend only on the van der waals lengths @xmath773 and @xmath774 , and the scattering length @xmath766 . however , the origin of this universality is different from that of the efimov - unfavoured limit and the case of three identical bosons . instead of a three - body repulsion , it is the van der waals potential @xmath764 between the two bosons that sets the three - body parameters , the same way it sets the scattering length between the two bosons . the authors of ref . @xcite have checked that this conclusion , obtained from the born - oppenheimer picture , is validated by exact calculations using the fully - coupled hyper - radial equations for mass ratios ranging from 14 to 29 . for these large mass ratios , they obtained a very good agreement between the born - oppenheimer and exact calculations for the wave functions and energies , and demonstrated that the results are nearly insensitive to the number of bound states in the two - body lennard - jones potentials @xmath764 and @xmath765 . the discovery of the van der waals universality for three particles rekindles the question of which conditions lead to a simple determination of the three - body parameter . the van der waals universality for two particles is a particular case of the universality of power - law tail potentials , which decay as @xmath791 , with @xmath792 . one can therefore expect that a similar universality exists for three particles interacting via power - law potentials . as for other finite - range interactions , ref . @xcite indicates that van der waals universality likely extends to any finite - range interaction that sufficiently suppresses the two - body probability at short distance . their conclusion is drawn from the similitude between the three - body parameter for deep pschl - teller potentials @xcite and that of deep van der waals potentials , once both are expressed in units of effective range . the relevant length scale for the three - body parameter would therefore be the effective range @xmath158 , which in the case of van der waals interactions is simply related to the van der waals length @xcite . extending the two - body analysis of section [ par : connection - with - two - body - physics ] to arbitrary potentials qualitatively corroborates this point : if the interaction suppresses the two - body probability within some range @xmath793 , the restriction of three - body configurations at small sizes imposes the three - body system to deform , and the kinetic energy of that deformation creates a three - body repulsive barrier at a hyper - radius comparable with the two - body suppression range @xmath793 . the effective range @xmath158 provides a good estimate of the suppression range . at unitarity , the effective range @xmath158 is defined by @xcite @xmath794,\label{eq : effectiverange}\ ] ] where @xmath795 is the asymptotic form of @xmath750 that is a solution of the free two - body problem . by construction , if the amplitude of @xmath744 is suppressed within some range @xmath793 with respect to that of @xmath796 , then the effective range is positive , and @xmath797 is a good estimate of @xmath793 . therefore the location of the three - body repulsive barrier , and thus the three - body parameter , should be given by the effective range . of course , the precise value of the three - body parameter should depend upon the precise location and shape of the repulsive barrier . these in turn should depend upon the precise shape of the two - body wave function @xmath750 . for interactions with a van der waals tail , we know that @xmath750 has a universal form in the region of suppression given by eq . ( [ eq : vanderwaalstwobodywavefunction ] ) , and thus the three - body parameter is universally related to @xmath715 . more generally , for interactions with a power - law tail decaying as @xmath798 ( @xmath792 ) , the two - body wave function at zero energy has the following universal form at unitarity : @xmath799 where @xmath800 , and @xmath801^{\frac{2}{n-2}}$ ] . with this notation , @xmath802 . for each power @xmath88 , there should thus be a universal relation between the three - body parameter and @xmath803 . in contrast , for interactions decaying faster than power laws , such as exponentially decaying potentials , there is no such universality of the two - body wave function . only when such potentials are very deep does the two - body wave function show a very abrupt depletion of probability that approaches a step function @xcite : @xmath804 the work of ref . @xcite investigates these ideas quantitatively using the separable potential approximation described in section [ par : connection - with - two - body - physics ] . the authors checked that for various finite - range interaction potentials near unitarity ( gaussian , exponential @xcite , pschl - teller @xcite , yukawa @xcite , morse @xcite , 6 - 12 lennard - jones @xcite ) , the separable potential eq . ( [ eq : separablepotential ] ) built with the corresponding zero - energy two - body wave function @xmath744 does reproduce within a few percent the three - body parameter extracted from exact calculations for three identical bosons @xcite . this confirms that , for pairwise potentials inducing a pronounced suppression of two - body probability , the three - body parameter is essentially governed by the zero - energy two - body wave function . as a result , it follows that the three - body parameter for such interactions roughly scales with the effective range . the numerical values of the three - body parameters for all the potentials considered in @xcite , when expressed in units of the effective range of the potential , differ by just a factor of two . namely , @xmath805\times(\frac{_{1}}{^{2}}r_{e})^{-1}.\label{eq : approximateuniversality}\ ] ] although this does not constitute a universal result , it is a significant reduction of variance with respect to the efimov log - period @xmath697 $ ] allowed by the zero - range theory . this fact may also be seen in the context of functional renormalisation group ( frg ) @xcite . in this framework , one applies a regulator that cuts off momenta smaller than @xmath17 , and looks at the flow of quantities , such as the effective three - body coupling constant , as a function of @xmath17 . the occurrence of the efimov effect at zero energy and the unitary limit implies a limit cycle , i.e. a flow that is log - periodic in @xmath17 , instead of a fixed - point limit . this can be intuitively understood by considering the log - periodic three - body wavefunction at zero energy eq . ( [ eq : f0bis ] ) confined in a box of size @xmath806 . the phase of the log - periodic oscillations is related to the three - body parameter . the authors of ref . @xcite checked that plotting the flow as a function of @xmath807 for different separable potentials ( similar to those of ref . @xcite ) results in phase differences that are small compared to @xmath808 . this confirms that the three - body parameter for these potentials is roughly determined by the effective range , in accordance with eq . ( [ eq : approximateuniversality ] ) . the exact calculations of ref . @xcite only feature potentials near unitarity with at most one @xmath4-wave two - body bound state . the authors of ref . @xcite then extended their separable potential calculations to the case of deeper potentials near unitarity . within the separable potential approximation , this amounts to constructing the separable potential from a two - body wave function with a larger number of nodes corresponding to the number of @xmath4-wave bound states in the original potential . for potentials with a power - law tail @xmath809 , because of the universality of the two - body wave function given in eq . ( [ eq : powerlawtwobodywavefunction ] ) , changing the depth of the potential results in little change in the three - body parameter . in the limit of deep potentials , the authors numerically found the following three - body parameters : @xmath810 here , the effective range @xmath158 is given by @xmath811 which can be obtained from eqs . ( [ eq : effectiverange ] ) and ( [ eq : powerlawtwobodywavefunction ] ) . note that for @xmath812 and @xmath813 , eq . ( [ eq : effectiverangeforpowerlaw ] ) reduces to @xmath814 and @xmath815 , respectively , and @xmath816 for large @xmath88 . for potentials decaying faster than a power law , as the depth of the potential is increased , the two - body wave function slowly converges to the step function given by eq . ( [ eq : stepfunctionwavefunction ] ) . as a result , the three - body parameter slowly converges to a universal limit , which ref . @xcite found to be numerically : @xmath817 the authors of ref . @xcite concluded that there are two classes of universality for the three - body parameter : the class of potentials decaying as power law , which exhibit a robust universality , and the class of potentials decaying faster than power laws , which give a universal parameter only in the limit of very deep potentials . the deep - potential limits are continuously connected , because the two - body wave function eq . ( [ eq : powerlawtwobodywavefunction ] ) for power - law potentials also tends to the step function eq . ( [ eq : stepfunctionwavefunction ] ) for very large @xmath88 . hence , as the power @xmath88 is continuously increased , the universal value of the three - body parameter continuously decreases from eq . ( [ eq:3bp - for - c4]-[eq:3bp - for - c6 ] ) to eq . ( [ eq:3bp - for - step - function ] ) , but requires deeper and deeper potentials to be reached . finally , let us remark that the square - well potential @xmath818 which is often used in model calculations , stands out as a particular case . its two - body wave function at unitarity does not show a suppression of probability at short distance , even when the depth @xmath819 is increased , and does not converge to eq . ( [ eq : stepfunctionwavefunction ] ) . therefore , it is not expected to exhibit the deformation - induced three - body repulsion , nor the universal three - body parameter of eq . ( [ eq:3bp - for - step - function ] ) . the problem stems from the absence of tail : there is only an abrupt variation of the potential that precludes any acceleration , even classically . if the abrupt variation is smoothed a bit , the three - body parameter should eventually reach the universal value eq . ( [ eq:3bp - for - step - function ] ) in the limit of deep wells . it is important to note that these results are obtained within the separable potential approximation ; they need to be confirmed and refined by exact calculations . the preceding discussions only considered interactions described by a single potential . in many physical systems with resonant interactions , the reality is more complex as the interaction involves the coupling of potentials from different channels , corresponding to different internal states of the colliding particles . for instance , as explained in section [ subsec : observations - with - atoms ] , the two - body interaction between ultra - cold atoms is made resonant by using feshbach resonances @xcite , which result from the coupling between two or more hyperfine channels . in such situations , the value of three - body parameter may not follow the results presented in the previous sections , and depends on the characteristics of the coupled channels . here , we consider the case of isolated feshbach resonances . in the neighbourhood of a feshbach resonance , two scattering particles at relative energy @xmath820 approach each other in some entrance channel corresponding to their internal states , but during their collision can couple to a bound state of energy @xmath821 in a closed channel ( i.e. whose potential dissociates above the energy @xmath120 ) corresponding to different internal states . the @xmath4-wave scattering phase shift is then the sum of two contributions : @xmath822 the first contribution is the background phase shift @xmath823 corresponding to the entrance channel , and the second contribution is a resonant phase shift @xmath824 induced by the coupling to the bound state . it has a breit - wigner form @xcite : @xmath825 where @xmath753 and @xmath826 are the width and shift of the resonance . at small scattering energy , @xmath827 , and thus @xmath824 can be expanded as : @xmath828 where @xmath829 and @xmath830 . it follows that the scattering length @xmath26 is @xmath831 where @xmath832 is the background scattering length . the resonance condition is met when the energy of the bound state @xmath821 is tuned to compensate the shift @xmath833 , making @xmath834 , and thus @xmath26 , divergent . the strength of the resonance is characterised by the length @xmath835 . when @xmath835 is much smaller than the range @xmath10 of the interaction ( the van der waals length @xmath715 in the case of atoms ) , the resonance is strong and dominated by the entrance channel ; the particles are most likely to be found in the entrance channel . such entrance - channel dominated resonances usually ( although not necessarily ) occur over a broad range of the tuning parameter ( such as an applied magnetic field ) , and thus are also called broad resonances . on the other hand , when @xmath835 is much larger than the range @xmath10 , the resonance is weak and dominated by the closed channel . such resonances are usually ( although not necessarily ) observed as narrow resonances . the strength of a resonance is thus conveniently characterised by the dimensionless ratio @xmath836 . broad resonances are dominated by their entrance channel and can be effectively described by a single potential @xcite . the results of sections [ subsec : van - der - waals - universality ] and [ subsec : other - types - of - interactions ] based on single interaction potentials can therefore apply to the case of such resonances . in particular , for broad atomic feshbach resonances , the van der waals tail of the open - channel potential is the main feature that determines the three - body parameter . in 2004 , dmitry petrov @xcite investigated the physics of three bosons near a narrow feshbach resonance . for narrow resonances , @xmath835 is much larger than the range @xmath10 of inter - particle forces , which induces the strong energy dependence of eq . ( [ eq : phaseshiftnarrowresonance ] ) . close to the resonance condition , one can neglect the background contribution @xmath837 , and comparing eq . ( [ eq : phaseshiftnarrowresonance ] ) with eq . ( [ eq : lowenergyphaseshift ] ) , we see that such resonant interactions have a large and negative effective range @xmath838 this confers to these systems some sort of long - range property , which has the effect of providing a three - body boundary condition for the efimov - attracted particles at distances on the order of @xmath839 , at much larger distance than the range of inter - particle forces . formally though , these systems can still be treated in the zero - range theory , on the basis of eq . ( [ eq : phaseshiftnarrowresonance ] ) , implying that the scattering length @xmath26 in eqs . ( [ eq : leehuangyangpotential ] ) or ( [ eq : bethepeierls ] ) is to be replaced by the energy - dependent scattering length @xmath840 given by @xmath841 where @xmath17 is the relative wave number between two particles . the work of ref . @xcite shows that unlike the original zero - range theory , the resulting three - body equations are well - behaved . indeed , the presence of the term @xmath842 in eq . ( [ eq : energydependentscatteringlength ] ) turns the efimov attraction eq . ( [ eq : efimovattraction ] ) at short hyper - radius @xmath72 into a coulomb - type attraction @xmath843 , which does not necessitate the introduction of a three - body parameter . another way to put it is that the three - body phase is set by @xmath835 . namely , the three - body phase as measured by @xmath844 was numerically found to be ( up to a factor @xmath845 ) @xcite : @xmath846 @xmath847 @xmath848 which predicts accurately the quantities @xmath849 and @xmath850 , except for @xmath688 , for which @xmath851 and @xmath852 . in 2008 , alexander gogolin and co - workers @xcite found an analytical solution to the three - boson problem near a narrow feshbach resonance . instead of the single - channel zero - range model based on eq . ( [ eq : energydependentscatteringlength ] ) , they used a two - channel model with no interaction in the entrance channel and a zero - range coupling between the entrance and closed channel . integrating the corresponding schrdinger equation , they showed that the resulting integral equation can be mapped to a single - particle schrdinger - like equation . from this equation , the three - body parameter can be expressed analytically , leading to an accurate value : @xmath853 @xmath854 it is from these calculations that the universal relation between @xmath254 and @xmath126 given in eq . ( [ eq : universal_relation_aminus_kappastar ] ) was calculated accurately . for the ground - state trimer , the theory gives @xcite @xmath855 it is remarkable that both the limit of very broad resonances and that of very narrow resonances lead to a universal three - body parameter in terms of the effective range of the interaction . in the case of broad resonances , the interaction can be described by a single potential , which lead to universal three - body parameters such as eqs . ( [ eq:3bp - for - c4 ] ) or ( [ eq:3bp - for - c6 ] ) . in the case of narrow resonances , the large and negative effective range leads to a universal three - body parameter given by eq . ( [ eq:3bpfornarrowresonancesaccurate ] ) . an intriguing question is how these two limits are connected for intermediate resonances which are neither very broad nor very narrow . in particular , one may wonder whether it can still be universally expressed in terms of the effective range , as the two limits suggest . the work of richard schmidt and co - workers @xcite investigates this point using a separable potential model to describe the coupled channels . this model treats the coupling between the entrance and closed channels , but does not include any interaction in the entrance channel . as a result , it does not reproduce the deformation and three - body repulsion discussed in section [ par : connection - with - two - body - physics ] that lead to the universal three - body parameter for broad resonances . the authors therefore adjusted the arbitrary form of of their inter - channel coupling ( an exponential function ) so that the three - body parameter in the limit of a broad resonance ( @xmath856 ) coincides with the known value for van der waals interactions , eq . ( [ eq : kappaforvdw ] ) . they could then calculate the three - body parameter as the strength of the resonance @xmath857 is decreased , using functional renormalisation group techniques . in the limit of narrow resonances ( @xmath858 ) , their calculation give @xmath859 and @xmath860 , reproducing the results eqs . ( [ eq:3bpfornarrowresonancesaccurate]-[eq : aminusfornarrowresonancesaccurate ] ) . for intermediate resonances ( @xmath861 ) , they obtain a smooth and continuous crossover connecting the two limits . ] . this is in contrast with the effective range , which changes sign as the strength of the resonance reduces : for broad resonances , the effective range is positive and on the order of the true range @xmath10 of the interaction ( see eq . ( [ eq : effectiverangeforpowerlaw ] ) ) and for narrow resonance , the effective range is negative and given by the length @xmath835 ( see eq . ( [ eq : effectiverangefornarrowresonances ] ) ) . this indicates that in this crossover region of intermediate resonances , the three - body parameter is not simply given by the effective range . this is to be expected because the universal mechanisms relating the three - body parameter to the effective range are different for the two limits : in the case of broad resonances , universality stems from the two - body short - range correlation eq . ( [ eq : vanderwaalstwobodywavefunction ] ) , which is an off - the - energy - shell property , whereas in the case of narrow resonance , universality stems from the energy - dependence of the scattering phase shift eq . ( [ eq : phaseshiftnarrowresonance ] ) , which is an on - the - energy - shell property . the work of yujun wang and paul s. julienne @xcite presents the most complete model so far . the two - body interaction is described by a set of two or three channels corresponding to the spin states involved in the feshbach resonance , and the potential in each channel is modelled by 6 - 12 lennard - jones potential . by incorporating both the resonance and van der waals physics , this kind of models is known to describe the two - body physics very accurately over an energy range comparable with the van der waals energy @xmath862 , in the same spirit as multi - channel quantum - defect theory @xcite . the authors of ref . @xcite argue that they should equally provide an accurate description of the three - body physics , in particular the three - body parameter . indeed , the feshbach resonance is decribed properly , both in the limit of narrow resonances and the limit of broad resonances where the van der waals tail of the potential determines the three - body parameter . moreover , the lennard - jones potentials support more than one bound state , allowing the description of recombination and relaxation processes to these bound states . solving the three - body problem numerically with such models , the authors of ref . @xcite could indeed reproduce the experimentally observed loss by three - body recombination or atom - dimer relaxation around several resonances : a broad resonance in cesium-133 ( @xmath863 ) , a double resonance in cesium-133 ( @xmath863 and @xmath863 ) , and a broad resonance in rubidium-85 ( @xmath863 ) . not only could they reproduce the location of efimov peaks giving the three - body parameter , but also the loss rate for scattering lengths outside the window of zero - range universality . this remarkable agreement is a further evidence of the three - body van der waals universality . the experimental efimov features considered in ref . @xcite are driven by broad resonances , and therefore satisfy the van der waals universal value of the three - body parameter , eq . ( [ eq : aminusforvdw ] ) . in principle , the model could also be used to investigate the case of intermediate and narrow resonances , although this was not detailed in ref . the authors point out that for these resonances the results should depend not only on the van der waals length @xmath715 and the resonance strength @xmath864 but also on other parameters such as the background scattering length @xmath865 ( a fact missing by construction in the work of richard schmidt and co - workers @xcite ) . even for the broad resonances , their calculations indicate that while @xmath696 remains largely insensitive to @xmath865 , the value of @xmath866 may depends on @xmath865 . a full mapping of the parameter space for feshbach resonances remains to be done . [ [ broad - resonances ] ] broad resonances + + + + + + + + + + + + + + + + in ultra - cold atom experiments , it is usually easier to deal with open - channel dominated resonances because they correspond to broad resonances in terms of the applied magnetic field . most of the measurements reported in fig . [ fig : van - der - waals - universality ] are obtained from relatively broad resonances . as mentioned in section [ subsec : broad - feshbach - resonances ] , broad resonances are expected to be well described by single - channel two - body potentials . indeed , the theoretical results of section [ subsec : van - der - waals - universality ] for single - channel van der waals potentials agree with the observations within 20% . this agreement has confirmed the van der waals universality of the three - body parameter for these resonances . however , reducing the tolerance reveals some discrepancies that seem significant . first of all , the theoretical calculation of @xmath867 for single - channel deep van der waals potentials gives a value close to @xmath868 , see eqs . ( [ eq : aminusforvdw ] ) and ( [ eq : aminusforvdwseparable ] ) , whereas most experimental values are above @xmath869 . another issue pointed out in ref . @xcite is that the presumably most precise experimental determinations of the three - body parameter , based on first - excited - state resonances , give values eqs . ( [ eq : experimentalvdwaminus1cs ] ) and ( [ eq : experimentalvdwaminus1li6 ] ) that differ significantly by 20% . in the absence of systematic errors , one has to conclude that while van der waals physics is the main ingredient determining the three - body parameter , it is not the only one . possible candidates are the deviation from the van der waals tail ( @xmath870 coefficient ) in the single - channel potential and coupled - channel effects . according to the calculations discussed in section [ subsec : intermediate - resonances ] , the coupled - channel effects tend to increase the value of @xmath254 , which may make it closer to the observed values . yet , more work is needed to refine our understanding . from the current theoretical and experimental results , one can only say that the value of @xmath254 for the broad atomic resonances is about @xmath871 , with an uncertainty of 20% . [ [ intermediate - and - narrow - resonances ] ] intermediate and narrow resonances + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + closed - channel dominated resonances , on the other hand , are most often narrow and necessitate a fine tuning of the magnetic field , which in turn requires a high stabilisation of the intensity of the current in the coil creating the magnetic field . there are therefore much less experimental observations for narrow resonances . the experimental group of giovanni modugno in florence @xcite have reported the measurement of the three - body parameter for seven different feshbach resonances in potassium-39 . these resonances correspond to a magnetic field of 58.92 , 60.1 , 65.67 , and 471.0 gauss for atoms polarised in the hyperfine state with projection @xmath872 along the magnetic field , 33.64 , 162.35 , and 560.7 gauss for @xmath873 , and 402.6 gauss for @xmath874 . the strength @xmath857 of these resonances has been calculated to range from 0.11 to 2.8 , and the background scattering @xmath865 ranges from -1.54 nm to -0.95 nm . the group found that the measured value of @xmath696 does not vary significantly from its expected value eq . ( [ eq : experimentalvdwaminus0 ] ) for broad resonances . although the resonances are not narrow enough to be fully in the regime described theoretically in section [ subsec : narrow - feshbach - resonances ] , one would have expected that the observations would show some indication of the crossover between the narrow and broad limits , as suggested by the models of @xcite . as of now , these observations remain to be interpreted theoretically . after the efimov effect was discovered , a natural question was whether the same effect could apply to a larger number of particles . in 1973 , amado and greenwood @xcite already concluded that there is no efimov effect for four identical bosons or more , in the sense that for @xmath324 , there is not an infinite number of @xmath5-body bound states near the appearance of an @xmath875-body bound state , as is the case for @xmath8 . in spite of this early negative result , it was later found that not only a @xmath876-body efimov effect can occur for mass - imbalanced fermions , but a variety of universal @xmath5-body bound states were found in the region where the @xmath877-body efimov effect occurs . here , we review the situation for bosons and mass - imbalanced fermi mixtures . schematic four - boson energy spectrum as a function of the inverse scattering length @xmath121 between each pair of bosons ( adapted from @xcite and @xcite ) . the black curves represent the dimer+boson+boson and dimer+dimer thresholds . the red curves represent the trimer+boson thresholds ( compare with the trimer energies of fig . [ fig : efimovplot ] ) . the solid purple curves represent the tetramer energies , and the dashed purple curves correspond to inelastic virtual tetramer states . here , the two tetramers associated with the ground - state trimer do not follow exactly the universal pattern exhibited by the tetramers tied to excited trimers , although this depends on the microscopic model . ] although amado and greenwood @xcite found from the trace of the four - body kernel of the four - boson integral equation that no four - body efimov effect occurs , they also acknowledged that near a two - body resonance where the three - body efimov effect occurs , there should also be four - body bound states . however , one fundamental question was whether in the limit of zero - range interactions a four - body parameter is required to set the four - body energy , just as a three - body parameter is required to set the three - body energy . amado and greenwood s result suggests that , in the limit @xmath878 , no four - body parameter is required . as a further evidence , j. a. tjon found by solving numerically the four - body problem for different models that the four - body energy is correlated with the three - body energy , a correlation referred to as the `` tjon line '' @xcite . on the other hand , the works of sadhan k. adhikari , tobias frederico , i. d. goldman , and yamashita @xcite on the perturbative renormalisation of the few - body problem with delta function potentials , and subsequent works @xcite , advocated the introduction of an @xmath554-parameter for each particle added to the @xmath5-body system . this question was also addressed by hans - werner hammer , lucas platter , and ulf - g . meiner @xcite@xcite , by solving the yakubovsky equations @xcite ( a generalisation to four bodies of the faddeev equations ) with a gaussian separable two - body and three - body potentials . the strengths of these potentials are adjusted ( renormalised ) such that the two - body and three - body energies are independent of the gaussian cutoff @xmath113 of the potentials . the authors found that there are two tetramer states below the ground - state trimer and that their energy is relatively independent of the cutoff @xmath113 , suggesting that no four - body renormalisation , and thus no four - body parameter is required . this led to some controversy on the necessity of a four - body parameter . the work of hans - werner hammer and lucas platter @xcite also suggested that the presence of two tetramer states below the ground - state trimer is a universal feature that also occurs below each of the excited trimer states . this point was confirmed by javier von stecher , jos p. dincao and chris h. greene in their study @xcite where they solved the four - boson problem in hyperspherical coordinates . the use of four - body hyper - radial potentials reveals the presence of a well below each trimer - boson scattering threshold , following the efimov geometric scaling of these thresholds . each potential well can support two bound states , one of which being just below the trimer - boson threshold , that is to say a trimer weakly bound to a boson . the existence of these states was confirmed by solving the coupled hyper - radial equations using the correlated gaussian basis set expansion . this infinite set of tetramer states have been referred to as `` universal tetramers tied to ( or associated with ) efimov trimers '' , to avoid the designation `` efimov tetramers '' which would suggest a four - body efimov effect ruled out in ref . @xcite . the work of von stecher and co - workers also proposed a solution to the controversy on the necessity of a four - body parameter . indeed , the location of the well in the four - body hyper - radial potential moves to a larger hyper - radius by a factor of 22.7 at each new trimer - boson threshold , making the corresponding tetramer states essentially insensitive to any short - range four - body force , as advocated in @xcite . on the other hand , the well associated with the ground - state trimer - boson threshold is located at shorter hyper - radii comparable with the range of interaction , thus making the corresponding tetramers sensitive to a short - range four - body force . this sensitivity makes to some extent the ground - state tetramer energies independent of the trimer energy , thus requiring in zero - range models the introduction of the four - body parameter advocated in @xcite . the precise four - body spectrum for excited states was calculated by arnoldas deltuva in a series of papers @xcite . this calculation had been challenging because the excited tetramers are resonant states embedded in trimer - boson continua . deltuva obtained the binding energies @xmath879 and widths @xmath880 of these states by calculating four - body scattering properties using the alt - grassberger - sandhas ( ags ) equations @xcite . here , @xmath88 refers to the @xmath88-th trimer of binding energy @xmath881 , which the two tetramers @xmath882 are associated with . at the unitary limit , and for large @xmath88 , the following universal relations were found : @xmath883 the whole four - body spectrum is shown in fig . [ fig : four - bosons ] . generally speaking , each pair of tetramers follows the trimer energy . the tetramer states thus form a superposition of two geometrical series with the efimov scaling ratio @xmath884 . the two tetramers appear from the four - body threshold before the appearance of the associated trimer and dissociate in the dimer - dimer scattering threshold . however , deltuva found that in the case of the tetramer resonances , the most weakly bound state first dissociates in the trimer - boson threshold , surviving as a inelastic virtual state , before reappearing from that threshold and eventually dissociating in the dimer - dimer threshold . there is an additional family of tetramer states which appear near the crossing of a trimer and the dimer - boson threshold . these tetramer states are simply a consequence of the efimov effect occurring for the system of dimer and two bosons , since the scattering length between the dimer and boson is resonant near this crossing . these particular features may not occur for the ground state tetramers , depending on the details of the short - range interaction . schematic energy spectrum of three heavy bosons and one light particle as a function of the inverse scattering length @xmath121 between the heavy boson and light particle ( adapted from refs . the same conventions as those of fig . [ fig : four - bosons ] are used . it is assumed that the mass ratio between heavy and light is larger than @xmath88513 . for mass ratios smaller than @xmath88513 , the second tetramer state would disappear at a negative value of the scattering length , instead of positive . the virtual states indicated by the dashed curves are a conjecture made by analogy with fig . [ fig : four - bosons ] . ] the four - body efimov spectrum was investigated in the case of heavy and light bosons mixtures by yujun wang and co - workers @xcite , and subsequently by doerte blume and yangqian yan @xcite . as in the case of identical bosons , there appears to be no four - body efimov effect in these mixtures , despite earlier claims based on the born - oppenheimer approximation @xcite . on the other hand , the works of refs . @xcite show that , as in the case of identical bosons , universal tetramer states consisting of three heavy and one light bosons are tied to the heavy+heavy+light efimov trimers ( see section [ subsec:2-bosons+1particle ] for a discussion of these trimers ) . the schematic four - body spectrum is given in fig . [ fig : three+one ] . tetramer states tied to excited trimers were evidenced in ref . @xcite from the calculated four - body recombination rate , while the authors of ref . @xcite only calculated the tetramers tied to the ground - state trimer but conjectured that similar tetramers exist for each excited trimer . in this latter work , two tetramers were found below the ground - state efimov trimer . they appear at negative scattering lengths , but the excited tetramer disappears in the trimer+heavy threshold for the mass ratio @xmath886 before reaching the unitary limit , while it persists to some positive scattering length for @xmath887 . on the other hand , in the work of ref . @xcite , only one tetramer state was found at mass ratios @xmath888 and @xmath889 . it is possible that the second tetramer was missed in that study because of its very weak binding energy . in ref . @xcite , the ground - state pentamer and hexamer were also calculated . they were found to follow the energy of the ground - state tetramer , as in the case of identical bosons . the previous results on universal tetramers tied to efimov trimers naturally raise the question of the universality of larger cluster of bosonic particles . although there is an extensive theoretical literature on bosonic clusters , motivated in particular by helium droplets , recent works have focused on the connection to efimov physics , and in particular whether bosonic clusters with resonant interactions can be universally described by a scattering length and a three - body parameter , as in the case of universal tetramers . this question has not been conclusively answered yet , because it requires the daunting task of calculating excited @xmath5-body cluster resonant states embedded in scattering continua of sub - clusters . so far , most studies @xcite have focused on the @xmath5-body bound states below the ground - state trimer , although one study @xcite was able to find @xmath5-body resonances up to @xmath287 below the first - excited trimer . these studies give us some idea of the properties of the conjectured universal clusters associated with excited efimov trimers . the earliest attempt at calculating the @xmath5-body clusters tied to the ground - state efimov trimer is the work of javier von stecher @xcite , solving by the diffusion monte - carlo method a model consisting of two - body square - well interactions and three - body repulsive hard - core interactions . von stecher found that the @xmath5-boson ground - state cluster systematically appears at a weaker two - body attraction than the @xmath6-boson cluster , and remains at a lower energy . this borromean binding property can be easily understood from the kinetic and interaction energy counting argument given in section [ sec : what - is - efimov ] . in this study , only the ground bound state has been calculated . in a subsequent study @xcite using different potential models and numerical techniques , von stecher identified three bound states for @xmath890 , and two bound states for @xmath287 . these results are qualitatively summarised in fig . [ fig : nbosons ] . in the work of mario gattobigio and alejandro kievsky @xcite , the same problem was investigated for systems of up to @xmath287 bosons interacting either through two - body gaussian potentials , or two - body pschl - teller potentials . in each case , the first and second @xmath5-body bound state were calculated . the results with gaussian two - body potentials were confirmed by yangqian yan and doerte blume @xcite , who also obtained results for two - body lennard - jones potentials , adjusted two - body helium-4 potentials , and two - body zero - range interactions with power - law @xmath891 three - body repulsive interactions . although all these results agree qualitatively with fig . [ fig : nbosons ] , they quantitatively disagree . figure [ fig : nbosonclusters ] shows the energy of the ground state cluster for some of these models . these models deviate as the number of particles @xmath5 is increased . this is not unexpected : as we have learnt from the preceding sections , the ground - state properties often deviate significantly from the universal pattern exhibited by excited states because the spatial extent of the ground states is comparable to the range of the interactions . interestingly , though , gattobigio and kievsky showed in ref . @xcite that these non - universal deviations ( for their own results and those of ref . @xcite ) could be mapped back for all @xmath5 ( up to @xmath287 ) to a single universal curve corresponding to the efimov trimer curve eq . ( [ eq : universalformula ] ) , generalising the modified universal formula eq . ( [ eq : modifieduniversalformula ] ) for @xmath892 . this observation suggests that there is a yet to be understood relationship between the non - universal ground - state clusters and the universal efimov trimer structure . schematic spectra of the @xmath5-boson clusters up to @xmath287 , as a function of the inverse scattering length @xmath121 between the bosons . this figure is based on the qualitative results of refs . trimers and tetramers correspond to the red and purple curves , as in fig . [ fig : four - bosons ] , and pentamers and hexamers are shown in blue and green , respectively . clusters below the ground - state trimer are non - universal , as they depend on the details of the interactions , whereas clusters below the excited trimers are believed to approach a universal pattern . this pattern is not well known : only a a few states have been calculated in ref . @xcite for negative scattering lengths . the region of positive scattering lengths offers many possible crossings and is virtually unknown . ] bosons at unitarity ( adapted from refs . @xcite ) : energy of the ground - state bosonic cluster ( normalised by the ground - state trimer energy ) as a function of the number of bosons , for different models of interactions at unitarity ( @xmath294 ) indicated by the arrows . the dotted and dashed curves are analytical predictions from refs . @xcite and @xcite , respectively . ] much less is known about the clusters tied to excited efimov trimers , which are resonant states presumed to have a universal structure . in ref . @xcite , javier von stecher could identify some of these states up to @xmath287 . they are schematically shown in fig . [ fig : nbosons ] , and qualitatively follow the pattern of the clusters associated with the ground - state efimov trimer for negative scattering lengths . this indicates that the ground - state clusters give us some idea of the spectrum of the excited clusters . the earlier work of ref . @xcite attempted to make these ground - state clusters close to the universal clusters by using a model consisting of two - body square - well interactions and three - body hard core repulsive interactions . the resulting ground - state pentamer and hexamer were indeed found to agree relatively well with the excited pentamer and hexamer resonances found in ref . @xcite , much more so than the ground - state clusters of other models . nevertheless , it is unclear how much universal this model is , especially for large @xmath5 . to improve this situation , yan and blume considered an alternative model in an attempt to approach a purely zero - range model , which supposedly yields universal results for both the excited and ground clusters ( in fact , a purely zero - range model has no ground state ) . although two - body zero - range interactions can be implemented in their numerical method ( based on the path integral monte carlo method ) , three - body zero - range interactions can not be treated . the authors thus resorted to a three - body repulsive interaction of the form @xmath891 , where @xmath72 is the three - body hyper - radius - see eq . ( [ eq : hyper - radius ] ) , and carefully checked that when @xmath288 is increased , the three - body ground - state observables convincingly converge to that of the universal ( zero - range ) theory . it is thus plausible that the ground - state clusters of this model converge to the universal clusters for large enough @xmath288 . although the cluster energies are found to be rather insensitive to @xmath288 for small @xmath5 , for larger @xmath5 their energies become strongly dependent on @xmath288 . nevertheless , we noticed that the dependence on @xmath893 appears to be linear , which makes it easy to extrapolate to @xmath894 . in fig . [ fig : nbosonclusters ] , we have represented the result of this extrapolation by the red curve . at present , this curve represents the most plausible variation of the energy with @xmath5 for universal clusters at the unitarity limit . interestingly , it turns out to be close to the curves obtained for ground - state clusters for lennard - jones and scaled helium potentials , although these curves are expected to represent a different class of universality associated with van der waals potentials . there remain many open questions about the universal clusters . the region of positive scattering lengths have not been addressed yet , and promises to reveal a rich pattern of clusters dissociating into subclusters . there is also an intriguing possibility that the energy of clusters of a very large number of particles , if they exist , may leave the scaling window of the trimer they are originally associated with . in the theoretical study ref . @xcite on tetramers tied to efimov trimers , it was realised that experimental evidence of these tetramers could be seen through the enhancement of the four - body recombination loss rate at the scattering lengths where the tetramers appear at the four - body scattering threshold , something which had in fact already been observed in experimental data from ultra - cold cesium atom experiments at the university of innsbruck . in ref . @xcite , the experimentalists at innsbruck confirmed that the locations of these loss peaks at @xmath895 and @xmath896 ( where @xmath254 designates the scattering length at which a trimer appears , seen experimentally by a three - body loss peak ) are consistent with the expected locations @xmath897 and @xmath898 . a few years later , the same group reported the observation in the same system a weak five - body loss peak at the scattering length where a ground - state pentamer is expected to appear @xcite . two other groups , the group of randall g. hulet at rice university @xcite and the group of giovanni modugno and massimo inguscio in florence @xcite , also reported in 2009 the observation of the four - body loss peaks at the scattering lengths consistent with the above values , but it turned out later that their results were plagued by misassignments of the loss peaks and recalibration of the scattering length with respect to the magnetic field ( see section [ subsec : ultracold - atoms ] ) , and their results were modified in 2013 @xcite . the former group originally found two four - body loss peaks @xcite , but later in ref . @xcite , they could only observe a single peak at @xmath899 which is likely to correspond to one of the four - body bound states , while the other one is not observed . the latter group originally reported the observation of a single four - body loss peak at @xmath900 @xcite , but after reassignment of the peaks , no four - body loss peak was found @xcite . resonantly interacting four - body systems with identical fermions have also been studied recently . the first treatment of these systems was the exact calculation by dmitri petrov and co - workers @xcite of the dimer - dimer scattering length for a four - body system of two identical ( i.e. , spin - polarised ) fermions plus two other identical fermions . the four - body problem for fermions , while more challenging than that for identical bosons , is still tractable analytically and numerically . systems with identical fermions are subject to the repulsion originating from the pauli exclusion principle and are , generally speaking , less likely to support bound states than bosonic systems . however , this repulsion can be overcome by increasing the mass of two identical fermions with respect to that of the other two fermions , leading to the formation of a four - body bound state , as in the case of mass - imbalanced three - body system with fermions ( see section [ subsec : kartavtsev - malykh - universal - trimers ] ) . in this section , we review the recent theoretical progress on two classes of four - body systems which consist of resonantly - interacting identical fermions of two species : a system of two identical ( i.e. spin - polarised ) fermions plus two other identical fermions in section [ subsec:2-fermions-+2-fermions ] , and a system of three identical fermions plus another distinguishable particle in section [ subsec:3-fermions-+1particle ] . while more understanding has been gained for these four - body systems in the past decade , little is known yet for more than four particles and further studies are needed in this direction . the earliest works on the four - body problem in a two - component fermi mixture were motivated by the studies of the bec - bcs crossover @xcite . the nature and stability of the bose - einstein condensate phase of dimers made of the fermions is sensitive to scattering properties of the dimers . in some works @xcite , the dimer - dimer @xmath4-wave scattering length has been estimated with some approximations . exact calculations have been performed in refs . @xcite , and the dimer - dimer scattering length at equal mass has been found to be @xmath901 ( @xmath26 is the @xmath4-wave scattering length between the fermions ) , which is significantly smaller than the mean - field ( i.e. , the born approximation ) value @xmath902 due to the pauli exclusion principle . the exact calculation of the dimer - dimer @xmath4-wave scattering length has also been extended to the mass - imbalanced case in refs . @xcite , and the asymptotic behavior at large mass ratio @xmath903 ( @xmath904 is the fermion - dimer @xmath4-wave scattering length ) has also been found analytically @xcite . for a four - body system made of 2 identical fermions + 2 identical fermions , there necessarily exists a repulsion between each identical fermions due to the pauli exclusion principle , preventing the formation of a universal four - body bound state @xcite . indeed , for any parity and angular momentum channel , there is no universal four - body bound state when the mass ratio is smaller than the three - body efimov critical mass ratio @xmath905 @xcite : there is neither a four - body efimov effect at the unitary limit @xcite nor a universal four - body bound state of kartavtsev - malykh character for a positive scattering length @xcite . this is in marked contrast to the 3 + 1 fermi system discussed in the next section , where four - body bound states can appear below the three - body efimov critical mass ratio . on the other hand , if the mass ratio exceeds the three - body efimov critical mass ratio @xmath905 , the three - body efimov attraction arises and may bind the four particles . the resulting four - body bound states , however , are not expected to be four - body efimov states . since the introduction of the three - body parameter is known to regularise the four - body problem for a bosonic four - body system @xcite , it is expected that the four - body bound states of the 2 + 2 fermi system , if they exist , should also be characterized by the three - body parameter only , and would not require the introduction of a four - body parameter . they would therefore be tied to the three - body efimov states , in an analogous manner to the four - body bound states of a bose system ( see section [ sec : many - identical - bosons ] and refs . @xcite ) , and show the discrete - scaling symmetry with the same scale factor as the efimov trimers . in contrast to the 2 + 2 fermi system , the system of 3 identical fermions of mass @xmath209 plus a distinguishable particle of mass @xmath9 exhibits richer physics . in particular , the repulsion between the identical fermions can be suppressed by the attraction mediated by the other particle when the mass of the identical fermions is much larger than that of the other particle . this situation is similar to the 2 + 1 system ( see section [ subsec : kartavtsev - malykh - universal - trimers ] ) . as a result , physics similar to that of the 2 + 1 fermi system has been found to occur in the 3 + 1 fermi systems , as discussed below . yvan castin and co - workers have studied the 3 + 1 system at the unitary limit , and have found that a four - body efimov effect occurs , i.e. the existence of a four - body attraction leading to an infinite number of four - body bound states in the absence of three - body bound states . this effect occurs in the @xmath906 channel , where @xmath444 is the total angular momentum and @xmath907 is the parity of the four - body state , and for a mass ratio @xmath395 above the critical ratio @xmath908 @xcite , which is below the critical mass ratio @xmath909 for the occurence of three - body efimov effect for 2 + 1 systems . since there is no trimer at unitarity in the range of mass ratio @xmath910 , the binding of the 3 + 1 states is a genuine four - body phenomenon . these four - body efimov states exhibit discrete scale invariance with a scaling factor @xmath911 , where the exponent @xmath4 in the scaling factor is obtained by numerically solving the four - body schrdinger equation at the unitary limit . as in the three - body efimov effect , this leads to a transcendental equation that determines the value of @xmath4 . it is worthwhile to note that this is the first and so far the only known example of the four - body efimov effect in any physical system : for a four - body system of bosons , the four - body efimov effect does not occur @xcite , and there exists only a finite number of four - body bound states tied to each efimov trimers @xcite - see section [ subsec:4-body - states - associated ] . it is also interesting to note that some of the four - body efimov states are likely to persist beyond the three - body critical mass ratio @xmath909 , while some others are expected to mix with the trimer+fermion scattering continua . below the four - body efimov critical mass ratio @xmath908 , there is no universal four - body bound state at the unitary limit . however , at positive scattering length for a mass ratio @xmath912 , a universal four - body bound state was found numerically by doerte blume in ref . @xcite in the same @xmath906 channel as the four - body efimov states . this four - body bound state is universally characterised by the @xmath4-wave scattering length , and is independent of other short - range parameters . it can therefore be interpreted as a four - body analogue of the universal three - body bound states found by kartavtsev and malykh for mass ratio @xmath913 and @xmath914 ( see section [ subsec : kartavtsev - malykh - universal - trimers ] ) . just as the kartavtsev - malykh three - body bound states are remnants of the three - body efimov states appearing above the critical mass ratio @xmath909 , the universal four - body bound state may be regarded as a remnant of the four - body efimov states appearing above the critical mass ratio @xmath908 @xcite . note that , as in the case of the 2 + 1 fermi system ( see section [ subsec : kartavtsev - malykh - universal - trimers ] and refs . @xcite ) , other kinds of four - body bound states may exist for the 3 + 1 fermi system at unitarity even below the critical mass ratio , but they are non - universal @xcite in the sense that they depend on a short - range boundary condition that is not set by the scattering length but other short - range details of the interactions . so far , our focus has been on isolated systems with a relatively small number of particles . this approach is relevant to the description of some systems such as light nuclei or isolated molecules . however , many physical systems are composed of a very large number of particles . it is thus natural to ask oneself about the implications of efimov physics in this context . several studies have recently started to address this question . the first studies have looked into the influence of a many - body background onto efimov states , while more recent studies deal with the consequences of few - body efimov physics at the many - body level . the observation of efimov physics in ultra - cold atom experiments involve the existence of triatomic molecules that can be formed from an extremely dilute cloud of atoms . even though the density of the cloud , typically @xmath915 atoms per cubic centimetre , is small enough to regard the triatomic molecules as isolated , it is natural to wonder how the properties of such molecules are changed under the influence of a surrounding medium . it is particularly interesting that the medium may be composed of the same constituents as the those of the molecule , as this consideration constitutes a first step towards many - body problems . depending on the quantum statistics of the constituents , there are thus two possible media , a fermi sea or a bose gas . let us consider an efimov trimer containing one or several fermionic particles , and surrounded by one or several seas of fermions that are identical to those of the efimov trimer . the presence of these many additional fermions constitutes a non - trivial many - body problem , but it can be treated in a first approximation as a static fermi sea . in this case , the main effect of the fermi sea is to prevent the fermions in the efimov trimer from occupying the states already occupied by the other fermions , owing to the pauli exclusion between identical fermions . this idea has been explored in the works of refs . @xcite . generally speaking , the pauli exclusion tends to reduce the binding of the efimov trimer . for a large enough density of the fermi seas , the efimov trimer eventually disappears . the successive disappearances of the different excited efimov states as the density is increased follow a scaling law with the universal scaling ratio @xmath916 @xcite . interestingly , the trimers can survive at positive energy , as a `` cooper triples '' , in analogy with the cooper pairs @xcite , a fact emphasised in ref . @xcite . the first study on the influence of a fermi sea on efimov states is that of davis james macneill and fei zhou @xcite . they considered two heavy bosons of mass @xmath209 immerged in a sea of light fermions of mass @xmath9 , assuming a resonant pairwise interaction between the bosons and the fermions . if the sea was composed of a single fermion , we know from section [ subsec:2-bosons+1particle ] that efimov trimers exist and can be interpreted in the born - oppenheimer picture ( see section [ subsec : the - born - oppenheimer - picture ] ) as the binding of the two bosons by the light fermion . the authors thus used the born - oppenheimer approximation , along with a semi - classical approximation , to calculate the three - body spectrum with the constraint the fermion can not occupy states of momenta smaller than the fermi momentum @xmath917 of the fermi sea . since this constraint breaks the translational invariance , the total momentum of the system does not simply shift the energy of the spectrum . for simplicity , the authors restricted their consideration to states of zero total momentum . for @xmath918 , they retrieve the vacuum efimov states of section [ subsec : the - born - oppenheimer - picture ] . increasing @xmath917 results in an increase of the trimer energies ( a decrease of their binding energy ) . as result , the infinite tower of efimov states is gradually pushed up , until the ground state disappears in the scattering threshold . the successive disappearances of efimov states follow a scaling law with the universal scaling ratio @xmath916 . a similar treatment for three kinds of fermions of equal mass was done in the works of nicolai gayle nygaard and nikolaj thomas zinner @xcite , and patrick niemann and hans - werner hammer @xcite . the work of ref . @xcite considered explicitly one fermi sea associated with one of the three fermions , while the work of ref . @xcite considered three fermi seas of equal fermi momentum @xmath917 . in both works , the problem was solved using the skorniakov - ter - martirosian three - body integral equation with the pauli exclusion constraint from the static fermi seas . the results are qualitatively the same as those of macneill and zhou @xcite , although the work of niemann and hammer @xcite emphasises the existence of solutions at positive energies , which they call `` cooper triples '' , in analogy with the cooper pairs . a limitation of the previous results is that the fermi seas are treated as static . in reality , the back action of the particles on the fermi seas can create particle - hole excitations near the surface of the fermi sea , an effect called polarisation of the sea . the authors of ref . @xcite estimated that the polarisation of the sea would reduce even further the binding of the efimov trimers . on the other hand , charles j. m. mathy and co - workers @xcite found in a somewhat different system that the polarisation of the sea may on the contrary enhance the stability of trimers . this work considers the case of a trimer made of a light fermion and two heavy fermions ( known as kartavtsev - malykh universal trimer , see section [ subsec : kartavtsev - malykh - universal - trimers ] ) , surrounded by a sea of identical heavy fermions . the authors used a variational ansatz involving both the trimer and the particle - hole excitation and found that the stability of the trimer is enhanced by a moderate density of the fermi sea . the case of efimov trimers in a bec ( bose - einstein condensate ) has been considered by nikolaj thomas zinner in ref . @xcite . in that study , two heavy particles ( impurities ) resonantly interact with bosons from a surrounding condensate of bosons . at low density , it is known that one of the bosons can bind to two heavy particles to form an efimov trimer , which can be easily interpreted in the born - oppenheimer approximation , as detailed in section [ subsec : the - born - oppenheimer - picture ] . the author of ref . @xcite thus used the born - oppenheimer approximation to calculate the effective interaction between the two heavy particles at fixed separations . to treat the effect of the surrounding condensate , the author used the bogoliubov approach @xcite to describe the bosons as a ground - state condensate with quasiparticle excitations . the author then retained only the coupling to quasi - particles , resulting in a three - body problem for two heavy impurities and a quasi - particle . although the validity of this approximation is not clear , it leads to results that are similar to those of ref . the resulting born - oppenheimer potential between the two heavy impurities is influenced by the medium at large separations @xmath72 , on the order of the coherence length @xmath136 of the condensate . in this region , the bonding potential is reduced with respect to the bonding potential in the absence of condensate ( see section [ subsec : the - born - oppenheimer - picture ] and fig . [ fig : bonding - potential ] ) , resulting in a faster decay . this in turn reduces the binding of the efimov states , as in the case of a fermi sea . however , in this theory , the potential appears to be not defined beyond a certain separation @xmath919 , so that these preliminary conclusions are to be confirmed by a more consistent theory . systems of a single impurity atom resonantly interacting with a bose condensate have recently been realised by two independent groups ; one with potassium-39 atoms in two different hyperfine states by the group of jan arlt at aarhus university @xcite , and the other one with a mixture of rubidium-87 and potassium-40 by the group of eric cornell , and deborah jin at jila @xcite . efimov states may appear in these systems since two identical bosons can bind with the impurity to form an efimov trimer , as discussed in section [ subsec:2-bosons+1particle ] . this possibility was explicitly taken into account for the impurity - bec system in the work of jesper levinsen , meera m. parish , and georg m. bruun @xcite , by constructing a variational ansatz that includes up to two bogoliubov excitations of the bec . this allows to take into account the three - body correlations of the impurity with two bosons of the condensate . if one includes only two - body correlations , the resulting variational ground - state is a `` bose polaron '' , i.e. the impurity is dressed by the surrounding condensate and , as the impurity - boson interaction is increased , progressively binds with one of the bosons to form a dimer surrounded by the remaining bosons . by contrast , taking into account three - body correlations , the bose polaron instead turns into a trimer composed of the impurity bound to two bosons and surrounded by the remaining bosons . the authors indicate that this state may be seen as the avoided crossing between the two - body correlated polaron with the vacuum ground - state efimov trimer composed of the impurity and two bosons . in the experiments @xcite , such an avoided crossing could not be observed since the efimov trimers are much larger than the mean atomic distance , but it would appear if one can prepare a gas with much smaller density . interestingly , the energy of the trimer dressed by the medium is lower than that of the vacuum trimer , showing that in this case the surrounding condensate stabilises the efimov trimer . given these results , it would be tempting to think that by taking a larger number of bogoliubov excitations , one could couple the polaron to universal clusters similar to those discussed in section [ subsec:3-fermions-+1particle ] , such as a tetramer formed of three bosons and the impurity . while this is certainly to be expected , the authors of ref . @xcite argue that the couplings to these clusters would be smaller than that to the trimer , and possibly negligible . their argument is that the repulsive interaction between the bosons tend to reduce the coupling between the polaron and universal clusters . they checked that the coupling to the trimer is indeed reduced when the scattering length @xmath163 between the bosons is increased , relative to the scattering length @xmath254 between a boson and the impurity at which the trimer appears . since universal clusters are expected to appear at scattering lengths between a boson and the impurity that are even smaller than @xmath920 , they expect that the reduction of the coupling is comparatively stronger for larger clusters . luis aldemar pea ardila and stefano giorgini have also arrived at a similar conclusion with a quantum monte carlo calculation @xcite . since it became possible to adjust the scattering length of ultra - cold atoms close to unitarity thanks to magnetic feshbach resonances , experimentalists have hoped to realise the unitary bose gas , an intriguing strongly - correlated system which theorists have been excited about for many years @xcite . in particular , some theorists have wondered about the role of efimov physics in such a gas , and how it can be described by the three - body parameter of the atoms , unlike the unitary fermi gas which has no microscopic length scale . unfortunately , when the scattering length is tuned to large values , ultra - cold bosonic gases are found to be very unstable , especially in the quantum degenerate regime , because of enhanced loss by recombination of the atoms into the many bound states that exist for atomic interactions . it is for this reason that efimov trimers in ultra - cold gases have been evidenced essentially through features in these losses , rather than more direct obervations . nevertheless a metastable unitary gas of density @xmath921 and temperature @xmath306 ( or thermal de broglie wavelength @xmath922 ) can be prepared in the non - degenerate regime @xmath923 @xcite , and it is possible to observe the gas dynamics in the degenerate regime @xmath924 @xcite . here we review some theoretical and experimental works that attempt to reveal the role of efimov physics in an atomic bose gas . shina tan @xcite has introduced a set of universal relations for the two - component fermi gas that relates its properties to the scattering length @xmath26 between two different fermions through the strength of two - particle short - range correlations , characterised by an extensive quantity called the `` contact '' @xmath925 . this quantity could be directly measured through radio - frequency ( rf ) spectroscopy in a number of experiments with ultra - cold atomic fermi gases . the notion of contact was generalised for bosons by several authors @xcite . it appears that , in addition to the two - body contact , that gives the variation of energy @xmath120 of the bose gas with respect to the scattering length @xmath26 , @xmath926 the occurrence of efimov physics for bosons requires to introduce a three - body contact @xmath927 , that gives the variation of energy with respect to the three - body parameter @xmath126 , @xmath928 the rf response of a bose - einstein condensate of rubidium-85 was recently investigated experimentally at jila @xcite . this three - body contact is expected to introduce in the rf response a frequency dependence that is proportional to @xmath927 and has a log - periodicity that characterises efimov physics @xcite . although the contribution from the two - body contact was clearly seen in the experiment , no log - periodic contribution from the three - body contact could be evidenced . this was explained by subsequent calculations by d. hudson smith and co - workers in ref . @xcite which determined that for the dilute bose gas of volume @xmath757 : @xmath929 from this expression , the authors found that the value of @xmath927 is indeed too small to be observed in the experiment . in a subsequent experiment , the experimentalists at jila were able to measure the momentum distribution in their bose - einstein condensate of rubidium at unitarity , before the three - body losses set in and deplete the gas @xcite . this distribution was found to saturate to a seemingly universal distribution . the tail of this momentum distribution is known to be related to the two - body and three - body contacts @xcite . as in the rf spectroscopy case , the three - body contact introduces a contribution which is proportional to @xmath927 and has the efimov log - periodicity in momentum . from dimensional analysis , d. hudson smith and co - workers @xcite found that for the unitary bose gas , @xmath930 there is currently no theoretical prediction for the values of @xmath74 and @xmath931 . by fitting the experimental measurement of the momentum distribution , assuming that the observed variations correspond to the log - periodic prediction for the tail , the authors of ref . @xcite obtained @xmath932 and @xmath933 . in the non - degenerate regime @xmath923 , the equation of state of the unitary bose gas can be treated by the so - called virial expansion @xcite : @xmath934 where @xmath935 , @xmath936 ... are the virial coefficients . because the third coefficient is related to three - body correlations , it is expected to depend on efimov physics . yvan castin and flix werner have studied the virial coefficients at unitarity @xmath294 @xcite and found an analytical expression for the first virial coefficients in the zero - range limit : where @xmath126 is the three - body parameter defined from the ground - state trimer energy @xmath938 - see section [ subsec:3bp - in - the - zero - range ] , and the function @xmath939 admits the low- and high - temperature limits : @xmath940 @xmath941 where @xmath942 and @xmath943 is euler s constant . at high temperature , the gas therefore exhibits a dependence on temperature that has the log - periodicity associated with efimov physics . the authors however noted that the validity of the zero - range model is expected to break down in this limit . away from unitarity , the second and third virial coefficients were recently calculated numerically in ref . @xcite , as a function of the scattering length @xmath26 and three - body parameter @xmath126 . these numerical results are consistent with the above analytical predictions at unitarity . schematic phase diagram of unitary bosons as a function of pressure and temperature normalised by the binding energy per particle @xmath428 in the efimov liquid phase ( adapted from the path - integral monte carlo results of ref . the value of @xmath428 is related to the energy @xmath944 of the ground - state efimov trimer at unitarity , although it appears to be model - dependent ( see fig . [ fig : nbosonclusters ] ) . in the calculation of ref . @xcite , @xmath945 . ] the degenerate regime @xmath924 of the unitary bose gas is more speculative since strong losses occur in experiments with atoms . nevertheless , the recent experimental achievement of ref . @xcite has raised hope for the investigation of the degenerate unitary bose gas . the recent theoretical developments in few - body efimov physics indicate that bosons may form universal excited @xmath5-body clusters governed by efimov physics - see section [ subsec : universal - clusters ] . similar clusters exist below the ground - state efimov trimer , although they are not necessarily universal . the tendency of bosons to cluster near unitarity indicates that the system as a gas is metastable . this raises questions about the ground state of the system . the results of numerical investigations of @xmath5-body clusters shown in fig . [ fig : nbosonclusters ] suggest that the energy per particle tends to a negative constant for large @xmath5 , although this constant depends strongly on the model . a negative constant energy per particle would imply that the system becomes a liquid for large @xmath5 . based on this idea , swann piatecki and wener krauth @xcite investigated the possibility of a liquid phase in the unitary bose system , using the path - integral monte carlo method to numerically solve the same model as that of ref . @xcite , _ i.e. _ bosons with two - body zero - range interactions and three - body hard repulsive core . they obtain the phase diagram shown in fig . [ fig : efimovphase ] for a homogeneous system . they found indeed that for sufficiently low temperature and pressure , the system becomes a liquid , which they call the `` superfluid efimov liquid '' . as expected , the density of this liquid is fixed by the trimer energy , _ i.e. _ the three - body parameter . we should note that the model is quantitatively different from that of zero - range interactions or shallow van der waals interactions , as can be seen in fig . [ fig : nbosonclusters ] . the obtained phase boundaries are therefore likely to be neither universal nor quantitative for a realistic atomic system . moreover , it is yet unclear how stable the efimov liquid phase is in an realistic atomic system , which interacts through deep van der waals potentials , since further decay would occur to more deeply bound states . yet , the idea of an efimov liquid , essentially bound by the efimov attraction is quite compelling . a particularly intriguing point is whether the discrete scale invariance still holds in this many - body system , implying that excited metastable liquid phases of densities smaller by factors of @xmath946 could exist , at least in principle . as discussed in section [ sec : multi - component - systems ] , the efimov effect occurs in multi - component fermi systems , i.e. mixtures of fermions of different kinds or with different spins that interact resonantly . efimov trimers or related universal trimers may therefore be formed in these systems . a striking difference with bosonic systems , however , is that it is more difficult for more than three fermions to bind , due to the pauli exclusion between identical fermions . as a result , a relatively stable phase of trimers may appear under certain conditions in these systems . recent studies have started to investigate this possibility . for fermions of equal masses , three kinds of fermions are necessary to exhibit the efimov effect . in the work of paulo bedaque and jos dincao @xcite , the zero - temperature phase diagram of the equal - mass three - component fermi gas is sketched out qualitatively as a function of the scattering lengths @xmath947 between the different components 1 , 2 , 3 . their reasonning is based on how energetically favourable it is for certain components to pair , and how the condensation of these pairs at zero temperature gives different symmetries of the order parameter , corresponding to different phases . however , they note that , beyond pairing , efimov three - body physics should also be taken into account , in particular the resonant enhancement of fermion - pair scattering at certain values of the scattering lengths @xmath948 . according to the authors , this would result in additional phases where the pairs and fermions are spatially separated due this enhanced repulsion , instead of forming a mixture . in his work @xcite , yusuke nishida goes one step further by explicitly considering the possibility of three fermions to form a ground - state efimov trimer to miminise their energy . the zero temperature phase diagram , as a function of the scattering length @xmath26 ( assumed to be the same for all pairs of components ) and the three - body parameter , consists of three phases : a fully paired supefluid , a partially paired superfluid with remaining unpaired fermions , and trimer phase , which is assumed to be a fermi gas of ground - state trimers . nishida calculates the boundaries of these phases in limits where they can be calculated exactly using a narrow - resonance model parameterised by @xmath26 and @xmath835 ( see section [ subsec : coupled - channel - interactions ] ) : * the high - density limit @xmath949 of the transition between the fully paired superfluid and partially paired superfluid , * the dilute limit @xmath950 of the transition between the superfluid and the trimer phase at negative scattering length @xmath151 , which is given by eq . ( [ eq : aminusfornarrowresonancesgroundstate ] ) indicating the appearance of a ground - state trimer * the dilute limit @xmath951 of the transition between the superfluid and trimer phase at positive scattering length @xmath153 , which is obtained by comparing the energies of a fermi gas of trimers and a bose - einstein condensate of dimers . here , @xmath917 denotes the fermi momentum of the system . the schematic phase diagram is represented in fig . [ fig : three - component - phase - diagram ] . the author confirmed the qualitative aspects of that diagram by solving a simple mean - field model including the trimers as a noninteracting fermi gas . the author also pointed out that within the partially paired superfluid phase , there occurs a fermion - trimer continuity : the unpaired fermions gradually turn into trimers by binding with pairs as @xmath952 is decreased . this effect is anologous to the quark - hadron continuity in nuclear matter . a qualitatively similar phase diagram is expected for broad resonances , where in general the three - body parameter @xmath723 plays the role of @xmath953 . we note that in a previous work @xcite yusuke nishida also conjectured the existence of a trimer phase in a two - component fermi gas where one component is free and the other is confined in two separate layers , making the system resemble a three - component system since the fermions confined in the different layers are distinguishable . as seen in section [ sec : mixed - dimensions ] , this situation leads to the efimov effect for one free particle resonantly interacting with two particles confined in different layers . near this resonance , it is therefore expected that the ground - state efimov trimer leads to a trimer phase at sufficiently low density , as in the three - component fermi gas . conjectured phase diagram of the three - component fermi mixture with fermi momentum @xmath917 , for the same narrow scattering resonance , parameterised by @xmath26 and @xmath835 , between all pairs of fermions ( adapted from ref . @xcite ) . ] in mass - imbalanced two - component fermi systems , efimov trimers exist when the mass ratio between heavy and light fermions exceeds @xmath909 , as seen in sections [ subsec:2-fermions-1particle ] and [ subsec : kartavtsev - malykh - universal - trimers ] . however , it is challenging to observe many - body physics induced by these efimov trimers in ultra - cold atom experiments , because such efimov trimers , when made of atoms , are unstable against recombination into an atom plus a tightly bound dimer ( see section 15.1 ) . on the other hand , the universal trimers , which are remnants of the efimov trimers in the range of mass ratios @xmath954 , are stable against three - body recombination thanks to the repulsion created by the pauli exclusion principle ( see section [ subsec : kartavtsev - malykh - universal - trimers ] ) . therefore , a gas composed of the universal trimers seems to be a promising candidate to observe a stable efimov - induced many - body phase in ultra - cold atoms . such a possibility has been studied in refs . @xcite and @xcite . considering the mass ratio @xmath955 to avoid the formation of universal tetramers ( see ref @xcite and section [ subsec : universal - four - body - bound ] ) , a stable many - body phase of the universal trimers has been predicted to exist in a range of scattering lengths and population imbalance between heavy and light fermions . when the scattering length is small and positive so that the binding energy of the universal trimer is large enough , the trimer can be regarded as a point - like composite fermion , having three internal degrees of freedom originating from its angular momentum @xmath453 . the trimer gas thus becomes a three - component fermi gas , each component corresponding to one of the three rotational states , @xmath956 . since the @xmath4-wave interaction between the universal trimers would be the dominant interaction of the trimer phase at low energy , the authors have found that its low - energy effective hamiltonian has an su(3 ) symmetry . furthermore , in ref . @xcite , the resonating group method was used to obtain an estimate of the interaction between the two universal trimers . the interaction was found to be of the soft - core repulsion type , leading to a positive @xmath4-wave scattering length for the trimer - trimer scattering . this would imply that the corresponding trimer phase , in the limit of low density and low temperature , is not superfluid , but a three - component , su(3 ) fermi liquid @xcite . we should note that the existence and nature of this trimer phase await further confirmation , since the crucial assumption about the absence of larger clusters ( e.g. pentamers , hexamers ) has not been precisely validated , and the method used to determine the trimer - trimer interaction is only approximate . while the mass ratio window @xmath957 seems rather restrictive , an ultra - cold mixture of @xmath958 and @xmath959 atoms falls into this window and is a promising candidate to confirm the existence and investigate the properties of this trimer phase . the efimov effect , in its most restrictive definition ( see section [ subsec : what - is - an - efimov - state ] ) , could be simply regarded as an oddity in the energy spectrum of three particles with short - range interactions . on the other hand , it could be argued that the efimov effect is on the contrary a central concept around which a wide range of strongly - interacting systems may be described . such is the case of long - studied systems such as the tritium nucleus or two - neutron halo nuclei in nuclear physics ( see sections [ subsec : observations - in - nuclear ] and [ subsec : observations - in - nuclear - multi - component ] ) , or the triatomic molecule of helium-4 in atomic physics ( see section [ subsec : observations - with - atoms ] ) . even though these systems may not be recognised as efimov states in the strictest sense , the efimov effect provides a simple framework for the existence of such compounds . the recent experimental observations with ultra - cold atoms and theoretical developments have now opened an even richer variety of systems related to efimov physics , from @xmath5-body universal clusters tied to efimov states , to the super - efimov effect , or mixed - dimensional efimov states . perhaps one of the key points of efimov physics is to shift the paradigm of two - body correlations in pairwise interacting systems to three - body correlations due , or partly due , to the efimov attraction . in this regard , what we have learnt from efimov physics appears to be quite promising for the study of many - body systems where such three - body correlations may play an important role . this work has greatly benefitted from discussions with doerte blume , takumi doi , yasuro funaki , chao gao , chris greene , jesper levinsen , haozhao liang , lucas platter , ludovic pricoupenko , jean - marc richard , and zheyu shi . it was partially supported by the riken ithes project . in section [ subsec : efimov - theory ] , the problem of three identical bosons interacting via zero - range forces was solved using the faddeev equations in hyper - spherical coordinates . that approach has the advantage of revealing the efimov effect in a transparent manner , and provides some analytic results . for the purpose of solving the problem numerically , however , it is often preferred to use integral equations in momentum space . these equations were first derived by g. v. skorniakov and karen a ter - martirosian @xcite , and take advantage of the contact nature of the interaction to reduce the dimensionality of the problem . in general , the three - body problem requires @xmath960 coordinates in @xmath194 dimensions . for translationally invariant systems , one can eliminate @xmath194 coordinates associated with the centre of mass . with contact interactions , the number of coordinates can be further reduced by @xmath194 . additional rotational invariance may further reduce the remaining @xmath194 coordinates to just one , making the problem easy to solve numerically . it turns out that contact interactions are not necessary to obtain such simplification . it is sufficient to have a separable interaction , which enables to treat finite - range effects . in this appendix , we derive the skorniakov - ter - martirosian equation for three identical bosons interacting via a separable interaction ; the zero - range equation can be obtained by considering the limit when the separable interaction becomes a contact interaction . a separable interaction @xcite is represented by an operator of the form : @xmath961 which is a projector onto a state @xmath962 multiplied by a scalar @xmath136 . when applied to a two - body state @xmath759 , it gives in momentum representation : @xmath963 where @xmath480 denotes the relative wave vector between two particles . note that for later convenience , we use the same notation @xmath480 for the integration variable : it should be understood that all occurences of @xmath480 inside the integral refer to the integration variable . to make the choice of @xmath136 unique for a given @xmath758 , the function @xmath82 is normalised such that @xmath964 . for scattering states @xmath966 with an incoming wave vector @xmath967 , the previous equation can be written as @xmath968 with @xmath51 and @xmath969 . in this equation , one can recognise the @xmath306-matrix element : @xmath970 projecting eq . ( [ eq : separablepotential - scatteringstate ] ) onto @xmath82 , one gets a closed equation for @xmath971 which gives the straightforward solution , @xmath972 from which one obtains @xmath973 , @xmath974 this relation can be used to express the parameters @xmath136 and @xmath82 of the separable potential in terms of physical quantities such as the scattering length @xmath26 : @xmath975 where @xmath48 is a cyclic permutation of @xmath979 and @xmath980 is the wave vector of the @xmath685th particle . in these coordinates , the three - body schrdinger equation reads : @xmath981 where the first term is associated with the kinetic energy , and the second term is the sum of the action of the separable interaction on the wave function @xmath38 over the three pairs 12 , 23 , and 31 . because of the bosonic exchange symmetry , @xmath982 can be replaced by @xmath983 inside the integral of eq . ( [ eq : appendixb1 ] ) . as in eq . ( [ eq : separablepotential - action ] ) , it should be understood that @xmath984 inside this integral refers to the integration variable , such that the integral term , once integrated , depends only the remaining jacobi wave vector @xmath985 . one can thus write : @xmath986 where @xmath987 eq . ( [ eq : appendixb2 ] ) can be inverted as @xmath988 where @xmath969 . for three - body scattering states , @xmath989 and @xmath990 is a solution of the non - interacting problem for three particles at that energy , providing the asymptotic boundary condition . for states with at least two bound particles , one has @xmath991 . in the remainder , we will restrict our consideration to the latter case . inserting eq . ( [ eq : appendixb4 ] ) into eq . ( [ eq : appendixb3 ] ) gives : @xmath992 making the choice @xmath993 , one can factorise one of the terms in the sum with the left - hand side of eq . ( [ eq : appendixb5 ] ) as follows : @xmath994 expressing the jacobi coordinate sets @xmath995 and ( @xmath996 ) in terms of @xmath976 , one finds and @xmath998 so that @xmath999 and therefore @xmath1000 and @xmath1001 . performing a change of integration variable @xmath1002 and @xmath1003 in the first and second integrals of the sum , and relabelling the integration variable as @xmath1004 in both integrals , one finally arrives at the integral equation for @xmath262 : @xmath1005 where the wave vector @xmath967 corresponds to the energy @xmath1006 . this integral equation on @xmath262 constitutes the skorniakov - ter - martirosian equation for three identical bosons interacting via a separable interaction . the remarkable point of this equation is that it replaces the original of the three - body schrdinger equation ( [ eq : appendixb1 ] ) for the unknown function @xmath982 of two three - dimensional variables by an equation on a function of only one three - dimensional variable , which is not possible for a general interaction . for a rotationally invariant system , the equation can be reduced to independent equations for each partial wave @xmath1007 that depends only on the one - dimensional variable @xmath1008 . in order to solve eq . ( [ eq : skorniakov - termartirosyan ] ) numerically to obtain the three - body bound states , one writes the left - hand side of eq . ( [ eq : skorniakov - termartirosyan ] ) as a matrix acting on @xmath262 ( through a discretisation scheme or spectral method ) and looks for the energies @xmath105 that make one of its eigenvalues equal to zero , in order to satisfy the right - hand side of eq . ( [ eq : skorniakov - termartirosyan ] ) . the corresponding eigenvectors @xmath262 give the three - body wave functions @xmath38 through eq . ( [ eq : appendixb4 ] ) . the skorniakov - ter - martirosian equation can be generalised to distinguishable , fermionic or any mixture of particles . in general , there are three functions @xmath1009 @xmath1010 to describe the three pairs of particles , and they are solutions of three coupled integral equations @xcite . the interaction can also be generalised to multi - channel interaction @xcite . there have also been generalisations to the relativistic case - see section [ subsec : relativistic - case ] . the zero - range limit can be obtained by setting @xmath1011 to a constant @xmath1012 . in this limit , the separable potential is just a constant @xmath136 in momentum space , corresponding to a delta function in real space . however , this limit gives rise to an ultraviolet divergence of the integrals . these divergences can be cured by imposing a momentum cutoff @xmath113 and renormalising @xmath136 in terms of the physical scattering length @xmath26 . formally , this is equivalent to setting @xmath1013 in the formulas , where @xmath197 denotes the unit step function . the integral equation ( [ eq : skorniakov - termartirosyan ] ) thus becomes , the equation ( [ eq : separablepotential - scatteringlength ] ) gives the renormalisation relation : @xmath1015 from this relation , one can express the @xmath306-matrix elements : @xmath1016 for sufficiently large @xmath113 , the on - shell two- body @xmath306-matrix element approaches @xmath1017 and the restriction @xmath1018 and @xmath1019 over the integration volume can be approximated by @xmath1020 . this results in the simplified equation , @xmath1021 which is the original equation derived by g. v. skorniakov and k. a. ter - martirosian @xcite . a remarkable point of this equation is that the two - body physics enters only through the on - shell @xmath306-matrix elements @xmath1022 and the cutoff @xmath113 . in general , for non - separable interactions , the off - shell @xmath306-matrix elements @xmath973 would be required . here , all the off - shell information is captured by the cutoff @xmath113 , as can be checked from the expression of @xmath973 in eq . ( [ eq : zerorange - tmatrix ] ) . this information is however essential for the three - body problem , and @xmath113 can not be set to infinity in the above integral , as the results would not converge but exhibit logarithmic oscillations with @xmath113 . it is the large but finite value of @xmath113 that sets the three - body parameter of the efimov states . because of the discrete scale invariance discussed in the efimov theory ( see section [ subsec : efimov - theory ] ) , scaling the value of @xmath113 by powers of @xmath916 gives the same three - body parameters and the same observables . it should be noted that the impossibility to take @xmath113 to infinity is due to the fact that only two - body interactions have been assumed . the three - body parameter may also be fixed by a three - body force . adding a @xmath113-dependent zero - range three - body interaction can cancel the dependence of the observables on @xmath113 , making it possible to take the limit @xmath1023 @xcite . the renormalised observables then depends on the two - body scattering length @xmath26 and a three - body parameter introduced by the three - body interaction . the choice of the parameters @xmath136 and @xmath1011 of the separable potential in eq . ( [ eq : separablepotential - definition ] ) depends on the system and observables of interest . in the windows of universality shown in fig . [ fig : efimovplotfiniterange ] , the observables depend only the two - body scattering length @xmath26 and the three - body parameter @xmath126 . to calculate these universal observables , any choice of @xmath136 and @xmath1011 leading to a desired @xmath26 and @xmath126 is possible . the most common choices are the zero - range limit @xmath1013 described above , and the gaussian separable potential with @xmath1024 @xcite , since they lead to analytical simplifications and simple relations between the physical quantities @xmath1025 and the parameters @xmath1026 . on the other hand , to calculate observables outside the universal region , that are affected by finite - range corrections , a more precise choice of the parameters is needed . as discussed in section [ subsec : finite - range - interactions ] , the interest of separable potential models over zero - range models is that they can account for the finite - range effects non - perturbatively . indeed , separable potential models can be parameterised to reproduce exactly the two - body scattering length and effective range , i.e. reproduce exactly the low - energy two - body observables . even when the scattering length and effective range are fixed , there remains some freedom to parameterise the separable potential , and the precise choice of the separable potential can change the value of the three - body parameter . as discussed in section [ subsec : other - types - of - interactions ] , the three - body parameter is to a great extent ( although not completely ) set by the effective range , so that many separable potentials ( such as gaussian ) having the correct scattering length and effective range already give a rough estimate of the three - body energies beyond the zero - range limit . if one has further information on the two - body interaction , such as off - shell @xmath306-matrix elements or a model potential for the interaction , one may construct an even more precise separable potential by fully exploiting its parameter space . namely , a separable potential @xmath758 can be designed to reproduce exactly an eigenstate @xmath759 at a given energy @xmath120 of a given local potential @xmath757 . it has the form @xcite : @xmath1027 which shows that the action of @xmath758 onto @xmath759 is indeed the same as @xmath757 , thus ensuring that @xmath759 is also an eigenstate of @xmath758 at the same energy . if @xmath759 is chosen to be the zero - energy scattering eigenstate , the separable potential has by construction the correct scattering length and correct effective range . indeed , the scattering length is given by the asymptotic form of the zero - energy radial wave function @xmath1028 ( see eq . [ eq : twobodywavefunction ] ) : @xmath1029{}\bar{\varphi}(r)=1-\frac{a}{r}\ ] ] and the effective range @xmath158 is obtained from @xmath744 through the formula @xcite , @xmath794.\ ] ] in this case , the separable potential of eq . ( [ eq : separablepotential - vparameterisation ] ) has the explicit parameterisation @xcite : @xmath1030 and @xmath136 is given by eq . ( [ eq : separablepotential - scatteringlength ] ) , @xmath1031 this separable representation was shown to reproduce approximately the three - body energies of the original potential @xcite , and in particular the three - body parameters of van der waals potentials @xcite - see section [ subsec : vdw - three - identical - bosons ] . as an example , we have constructed such a separable potential for helium-4 , using the zero - energy eigenstate obtained from the scaled lm2m2 potential of ref . @xcite , as solved for the ground - state energy as a function of scattering length ( varied by scaling the lm2m2 potential ) . the obtained energy is shown as a dotted curve in fig . [ fig : helium1 ] . note that the representation of a given potential in terms of a separable potential was generalised by ernst , shakin and thaler ( est ) @xcite , who have shown that any local potential @xmath757 can be represented exactly as a superposition of non - local separable potentials . we present here the separable model of the triton , first introduced by kharchenko @xcite and used to calculate the surfaces and curves of fig . [ fig : triton ] . this model describes the triplet and singlet interactions of nucleons by separable potentials of the form , @xmath1032 leading to the following integral equations : @xmath1033f_{t}(k)+4\pi\int\frac{d^{3}\vec{q}}{(2\pi)^{3}}\frac{\frac{1}{2}i_{\vec{k},\vec{k}^{\prime}}^{tt}f_{t}(q)+\frac{3}{2}i_{\vec{k},\vec{k}^{\prime}}^{ts}f_{s}(q)}{p^{2}+q^{2}+\vec{p}\cdot\vec{q}-\frac{me}{\hbar^{2}}}=0\label{eq : tritonstm1}\ ] ] @xmath1034f_{s}(k)+4\pi\int\frac{d^{3}\vec{q}}{(2\pi)^{3}}\frac{\frac{3}{2}i_{\vec{k},\vec{k}^{\prime}}^{st}f_{t}(q)+\frac{1}{2}i_{\vec{k},\vec{k}^{\prime}}^{ss}f_{s}(q)}{p^{2}+q^{2}+\vec{p}\cdot\vec{q}-\frac{me}{\hbar^{2}}}=0\label{eq : tritonstm2}\ ] ] where @xmath1035 the functions @xmath1036 and @xmath1037 are obtained from the zero - energy parameterisation eq . ( [ eq : separablepotential - zeroenergyparameterisation1 ] ) where @xmath750 is the two - body radial wave function , @xmath1038 of the zero - energy scattering eigenstate for the pschl - teller potential , @xmath1039 with the scattering length @xmath1040 where @xmath1041 and @xmath1042 designate the legendre polynomials and @xmath1043 is the harmonic number , which is equal to @xmath1044 for integral values of @xmath106 . for @xmath1036 ( respectively @xmath1037 ) , the parameters @xmath793 and @xmath106 are chosen to reproduce the triplet scattering length @xmath525 fm ( respectively the singlet scattering length @xmath1045 fm ) and the triplet effective range @xmath527 fm ( respectively the singlet effective range @xmath541 fm ) . the values are taken from ref . @xcite . to obtain the surfaces and curves of fig . 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this article reviews theoretical and experimental advances in efimov physics , an array of quantum few - body and many - body phenomena arising for particles interacting via short - range resonant interactions , that is based on the appearance of a scale - invariant three - body attraction theoretically discovered by vitaly efimov in 1970 . this three - body effect was originally proposed to explain the binding of nuclei such as the triton and the hoyle state of carbon-12 , and later considered as a simple explanation for the existence of some halo nuclei . it was subsequently evidenced in trapped ultra - cold atomic clouds and in diffracted molecular beams of gaseous helium . these experiments revealed that the previously undetermined three - body parameter introduced in the efimov theory to stabilise the three - body attraction typically scales with the range of atomic interactions . the few- and many - body consequences of the efimov attraction have been since investigated theoretically , and are expected to be observed in a broader spectrum of physical systems . @xmath0riken nishina centre , riken , wako , 351 - 0198 japan . @xmath1school of physics and astronomy , monash university , clayton , vic , 3800 , australia .

Two prison employees were killed and 10 others hospitalized with injuries after an attempted prison break in North Carolina, officials said. The North Carolina Department of Public Safety on Thursday night identified the fatalities as correctional officer Justin Smith, 35, who provided security in the Correction Enterprises Specialty Sewing Plant. He had worked as a correctional officer since 2012. The other fatality was correction enterprises manager Veronica Darden, 50, who supervised inmates working in the Specialty Sewing Plant. She had been a correction enterprises employee since 2007 and previously worked as a correctional officer. Three prison employees remain in critical condition, while seven were treated and released. Four inmates were also injured in the attempted prison break. North Carolina Gov. Roy Cooper said in a statement, "Those who work in our prisons do a difficult and demanding job that is critical to our safety. We're grateful to these fallen prison employees for their service, and we offer our condolences to their families, friends, coworkers and community on this tragic loss." The incident occurred Thursday afternoon at the Pasquotank Correctional Institute in Elizabeth City, a dispatcher at the Pasquotank County Sheriff's Office told ABC News. Around 3:30 p.m., an inmate set a fire in the sewing plant, which injured several employees, according to the North Carolina Department of Public Safety. Attempted escape at Pasquotank CI in Elizabeth City. Fires set in prison sewing plant. Several employees injured. More info when available. — NC Public Safety (@NCPublicSafety) October 12, 2017 "Our hearts are broken by this tragedy that took members of our Correction family," said W. David Guice, chief deputy secretary of the Division of Adult Correction and Juvenile Justice. "Words cannot express our deep sorrow. We will work closely with investigators to learn the circumstances of today’s incident and bring to justice those responsible." The prison currently houses 729 inmates, according to the department of public safety. Correction Enterprises, which works within the department, operates a sewing plant on site. Three of the 10 patients sent to the Sentara Albemarle Medical Center were transferred to the Sentara Norfolk General Hospital in Virginia, said Sentara Healthcare spokesperson Peter J. Sengenberger in a statement. The health care system asked the families of patients bring government-issued identification and the patient's full name with them to the hospital. The injuries to some of those involved are serious, according to Keith Acree, North Carolina Department of Public Safety spokesperson. He added that to his knowledge, no one escaped from the prison. The conditions of the patients were not released. Three local public schools were placed on lockdown following the incident. Students on school buses who had not already arrived home were brought back to the schools due to the potential of inmates being in the area, Elizabeth City-Pasquotank Public Schools said on Facebook. The lockdown has since been lifted. The situation is under control, the department of public safety said. Further details were not immediately available. ABC News' Alex Faul, Ben Stein and Rachel Katz contributed to this report. ||||| ELIZABETH CITY, N.C. (AP) — An attempted breakout by inmates from a North Carolina prison sent at least 14 people to hospitals Thursday, authorities said. The disturbance involved fires set in the prison's sewing plant, the state Department of Public Safety posted on its Twitter account. A spokesman for the state prison system said he couldn't provide immediate details of what had happened, how many sought to escape or how many were injured overall. But state correction authorities said the injured included several employees at the prison, the Pasquotank Correctional Institution in Elizabeth City, near the coast. The extent of those injuries wasn't immediately disclosed. No inmates managed to clamber beyond the prison walls, state prison spokesman Keith Acree said. Sentara Albemarle Medical Center in Elizabeth City received nine people requiring treatment, hospital spokesman Peter Sengenberger said. He added two of those patients were transferred and five other patients were being taken to a sister hospital about 50 miles (80 kilometers) to the north in Norfolk, Virginia. The prison can house nearly 900 adult, male felons in both high-security and minimum-custody buildings but the inmate population on Thursday was 729, the state correction agency said. Minimum-security prisoners work outside the walls on road gangs for the county recycling department and perform other community labor. The public school district locked doors at three nearby schools after getting word about 3:30 p.m. of the escape attempt. The notice came as students at one of the facilities, Pasquotank High School, were just to be released for the day and after dismissal times for the elementary and middle schools, said Tammy Sawyer, a spokeswoman for Elizabeth City-Pasquotank Public Schools. Buses were ordered back to their schools with any students still in transit. "We didn't want kids home alone or in transport with the potential situation that was unfolding," Sawyer said. Local emergency management officials said about 5 p.m. it was again safe for students to return home. The prison has reported other incidents this year. In April, an argument between two inmates at the prison led to one prisoner stabbing the other several times in the upper torso. Two months earlier, a guard was charged with trying to smuggle illegal drugs, phones and cigarettes behind prison walls.

– At least 14 people were injured Thursday afternoon in an attempted prison break in North Carolina, ABC News reports. The incident started with an inmate setting fire to the sewing plant at the Pasquotank Correctional Institute around 3:30pm. Details of the attempted prison break are scarce, and the extent of the injuries—some of which were to prison employees in the sewing plant—are unknown, according to the AP. WITN reports no inmates were able to escape. As the situation was unfolding, three schools in the area were put on lockdown. School buses taking children home brought them back to the schools for security reasons. Pasquotank houses 729 male prisoners in both high-security and minimum-custody facilities. Authorities say the situation is now under control.

SECTION 1. SHORT TITLE. This Act may be cited as the ``Computer Security Enhancement and Research Act of 2001''. SEC. 2. FINDINGS AND PURPOSES. (a) Findings.--The Congress finds the following: (1) The National Institute of Standards and Technology has responsibility for developing standards and guidelines needed to ensure the cost-effective security and privacy of sensitive information in Federal computer systems. (2) The application of best security practices developed by the National Institute of Standards and Technology is important for protecting sensitive, but unclassified, information controlled by Federal agencies. (3) The Federal Government has an important role in supporting research and education activities needed to ensure the security of future networked information systems in both the public and private sectors. (4) Technology, including applications of cryptography, exists that can be readily provided by private sector companies to ensure the confidentiality, authenticity, and integrity of information in electronic form associated with public and private activities. (5) The development and use of encryption technologies by industry should be driven by market forces rather than by Government-imposed requirements. (b) Purposes.--The purposes of this Act are to-- (1) establish research programs focused on improving the security of networked information systems; (2) promote the development of a vigorous academic research community engaged in leading edge research on computer and communications security; (3) reinforce the role of the National Institute of Standards and Technology in ensuring the security of unclassified information in Federal computer systems; and (4) promote technology solutions based on private sector offerings to protect the security of Federal computer systems. SEC. 3. RESEARCH ON THE SECURITY OF NETWORKED INFORMATION SYSTEMS. The National Institute of Standards and Technology Act is amended-- (1) by moving section 22 to the end of the Act and redesignating it as section 32; and (2) by inserting after section 21 the following new section: ``research program ``Sec. 22. (a) Establishment.--The Director shall establish a program to support research at institutions of higher education (where the term ``institution of higher education'' has the meaning given such term in section 101 of the Higher Education Act of 1965 (20 U.S.C. 1001)), for-profit research organizations, or consortia of such institutions, to improve the security of networked information systems. The program shall-- ``(1) include multidisciplinary, long-term, high-risk research; ``(2) include directed research to address needs identified through the activities of the Computer System Security and Privacy Advisory Board under section 20(e)(2) of this Act; and ``(3) promote the development of a substantial academic research community working at the leading edge of knowledge in subject areas relevant to the security of networked information systems. ``(b) Fellowships.--(1) In order to help meet the requirement of subsection (a)(3), the Director shall provide support for post-doctoral research fellowships and for senior research fellowships. Support for such fellowships shall be made available through research projects funded under the program established by subsection (a) and through a separate fellowship program described in paragraph (2) of this subsection. Senior fellowships shall be made available for established researchers who seek to change research fields and pursue studies related to the security of networked information systems. ``(2) The Director is authorized to establish a program to award post-doctoral research fellowships and senior research fellowships to individuals seeking research positions at institutions, including the Institute, engaged in research activities related to the security of networked information systems. To be eligible for an award under this paragraph, an individual shall submit an application to the Director at such time, in such manner, and containing such information as the Director may require. ``(3) Under this subsection, the Director is authorized to provide stipends for senior research fellowships at levels consistent with support for a faculty member in a sabbatical position and post-doctoral research fellowships at the level of the Institute's Post Doctoral Research Fellowship Program. ``(c) Awards; Applications.--The Director is authorized to award grants or cooperative agreements to institutions of higher education to carry out the program established under subsection (a). To be eligible for such an award, an institution of higher education shall submit an application to the Director at such time, in such manner, and containing such information as the Director may require. The application shall include a description of-- ``(1) the number of graduate students anticipated to participate in the research project and the level of support to be provided to each; ``(2) the number of post-doctoral research fellowships included under the project and the level of support to be provided to each; and ``(3) the number of senior research fellows anticipated to participate in the research project and the level of support to be provided to each. The Director shall ensure that a major consideration for making such awards shall be the emphasis and commitment demonstrated by the application to meeting the program requirement specified by subsection (a)(3). ``(d) Program Managers.--The Director shall designate employees of the Institute to serve as program managers for the program established under subsection (a). Program managers so designated shall be responsible for-- ``(1) establishing broad research goals for the program and publicizing the goals to the academic research community; ``(2) soliciting applications for specific research projects to address the goals developed under paragraph (1); ``(3) selecting research projects for support under the program from among applications submitted to the Institute, following consideration of-- ``(A) the novelty and scientific and technical merit of the proposed projects; ``(B) the demonstrated capabilities of the individual or individuals submitting the applications to successfully carry out the proposed research; and ``(C) other criteria determined by the Director, based on information specified for inclusion in applications under subsection (c); and ``(4) monitoring the progress of research projects supported under the program. ``(e) Review of Program.--(1) The Director shall-- ``(A) provide for periodic reviews by the senior staff of the Institute of the portfolio of research awards monitored by each program manager designated in accordance with subsection (d); and ``(B) seek the advice of the Computer System Security and Privacy Advisory Board, established under section 21, on the appropriateness of the research goals and on the quality and relevance of research projects managed by program managers in accordance with subsection (d). ``(2) The Director shall also contract with the National Research Council for a comprehensive review of the program established under subsection (a) during the 5th year of the program. Such review shall include an assessment of the scientific quality of the research conducted, the relevance of the research results obtained to the goals of the program, and the progress of the program in promoting the development of a substantial academic research community working at the leading edge of knowledge in the field. The Director shall submit to Congress a report on the results of the review under this paragraph no later than six years after the initiation of the program.''. SEC. 4. INTRAMURAL SECURITY RESEARCH. Section 20 of the National Institute of Standards and Technology Act (15 U.S.C. 278g-3) is amended-- (1) by redesignating subsection (d) as subsection (f); and (2) by inserting after subsection (c) the following new subsection: ``(d) As part of the research activities conducted in accordance with subsection (b)(4), the Institute shall-- ``(1) conduct research to address emerging technologies associated with composing a networked computer system from components while ensuring it maintains desired security properties; and ``(2) carry out multidisciplinary, long-term, high-risk research on ways to improve the security of networked information systems.''. SEC. 5. AUTHORIZATION OF APPROPRIATIONS. There are authorized to be appropriated to the Secretary of Commerce for the National Institute of Standards and Technology-- (1) for activities under section 22 of the National Institute of Standards and Technology Act, as added by section 3 of this Act, $25,000,000 for fiscal year 2003, $40,000,000 for fiscal year 2004, $55,000,000 for fiscal year 2005, $70,000,000 for fiscal year 2006, $85,000,000 for fiscal year 2007, and such sums as may be necessary for fiscal years 2008 through 2012; and (2) for activities under section 20(d) of the National Institute of Standards and Technology Act, as added by section 4 of this Act, $5,000,000 for fiscal year 2003, $5,200,000 for fiscal year 2004, $5,400,000 for fiscal year 2005, $5,600,000 for fiscal year 2006, and $5,800,000 for fiscal year 2007. SEC. 6. COMPUTER SECURITY REVIEW, PUBLIC MEETINGS, AND INFORMATION. Section 20 of the National Institute of Standards and Technology Act (15 U.S.C. 278g-3), as amended by this Act, is further amended by inserting after subsection (d), as added by section 4 of this Act, the following new subsection: ``(e)(1) The Institute shall solicit the recommendations of the Computer System Security and Privacy Advisory Board, established by section 21, regarding standards and guidelines that are being considered for submittal to the Secretary in accordance with subsection (a)(4). The recommendations of the Board shall accompany standards and guidelines submitted to the Secretary. ``(2) There are authorized to be appropriated to the Secretary $1,030,000 for fiscal year 2002 and $1,060,000 for fiscal year 2003 to enable the Computer System Security and Privacy Advisory Board, established by section 21, to identify emerging issues, including research needs, related to computer security, privacy, and cryptography and to convene public meetings on those subjects, receive presentations, and publish reports, digests, and summaries for public distribution on those subjects.''.

Computer Security Enhancement and Research Act of 2001 - Amends the National Institute of Standards and Technology Act to require the Director of the National Institute of Standards and Technology (NIST) to: (1) establish a program to support research at institutions of higher education, for-profit research institutions, or consortia of such institutions, to improve the security of networked information systems; (2) provide support for post-doctoral research fellowships and senior research fellowships in such areas; and (3) contract with the National Research Council for a comprehensive review of such program during its fifth year.Requires NIST to solicit recommendations of the Computer System Security and Privacy Board regarding Federal computing systems standards and guidelines.

ischemia - reperfusion injury ( iri ) is a phenomenon whereby cellular damage in a hypoxic organ is accentuated following the restoration of oxygen delivery . in the liver , this form of injury is recognized as a clinically important prolonged disorder.1 liver iri occurs as a result of some liver surgeries , liver transplantation , hemorrhagic shock , and prolonged portal triad clamping followed by reperfusion performed as an elective preplanned procedure or as an emergent maneuver to control excessive bleeding from the cut hepatic surface . it may also be said that liver iri is a complex process involving numerous cell types and molecular mediators in various pathophysiological and biochemical ways . the end result is cell death via a combination of apoptosis and necrosis involving a complex web of interactions between the various cellular and humoral contributors to the inflammatory response of kupffer cells , also producing proinflammatory cytokines , tumor necrosis factor alpha ( tnf- ) , interleukin ( il)-1 , lymphocytes , neutrophils , and hepatocytes.1,2 our knowledge regarding the mitochondria in generating reactive oxygen species ( ros ) , nitrogen species , and ionic disturbances , and in initiating mitochondrial permeability transition with subsequent cellular death in iri is continuously growing . however , the most promising protective strategy against iri explored during the last few years is ischemic preconditioning ( ip ) , which appears capable of increasing the resistance of liver cells to ischemia and reperfusion events . ip refers to brief periods of ischemia - reperfusion ( i / r ) followed by a prolonged one.3,4 the aim of the present study was to detect some of these mechanisms by subjecting rats to iri . all rats were treated in accordance with the guide for care and use of laboratory animals . the rats were kept at a constant room temperature under air conditioning at 25c for the duration of the study . the rats were divided into three groups ( n=10 each ) as follows : a sham operated control group ( group 1 ) ; an i / r group in which the liver was rendered ischemic by portal triad occlusion with a small bulldog vascular clamp for 60 minutes followed by reperfusion for 3 hours ( group 2 ) ; and an ip - i / r group in which animals were subjected to three cycles of 10 minutes of ischemia , each followed by 10 minutes of reperfusion prior to prolonged i / r , as in group 2 ( group 3 ) . at the end of the experiment , the animals were sacrificed by decapitation , and blood and liver samples were collected for analysis . the plasma was separated , and the liver was excised , de - encapsulated , washed with ice - cold saline , and then homogenized in phosphate - buffered saline . the following parameters were measured in plasma and/or liver homogenate : liver function tests , ie , alanine aminotransferase ( alt)5 and aspartate aminotransferase ( ast)5 oxidative stress parameters , ie , lipid peroxidation end products , including malondialdehyde ( mda ) using thiobarbituric acid,6 reduced glutathione ( gsh),79 oxidized glutathione ( gssg),79 and ratio of nitrite to nitrate in plasma ( nox)10,11 antioxidant enzyme activity , ie , superoxide dismutase ( sod)12 and glutathione peroxidase ( gpx)13 protein concentration in liver homogenate14 proinflammatory cytokines , ie , il-1 and tnf- , by enzyme - linked immunosorbent assays ( predicta ; genzyme , san diego , ca , usa ) liver glycogen concentration.16 the data are presented as the mean standard error and were analyzed using two - way analysis of variance followed by the least significant difference test using statistical package for the social sciences version 20 software ( ibm corporation , armonk , ny , usa ) . the data are presented as the mean standard error and were analyzed using two - way analysis of variance followed by the least significant difference test using statistical package for the social sciences version 20 software ( ibm corporation , armonk , ny , usa ) . table 1 shows an increase in serum ast , alt , plasma il-1 and tnf- , and tissue il-1 and tnf- in the i / r group as compared with the sham operated control group . however , the ip group showed a decrease in all these parameters compared with the control and i / r groups , but plasma tnf- was increased compared with the control and tissue il-1 was increased when compared with the control group and tissue tnf- was increased when compared with the control and i / r groups . the significant results shown in table 1 show a decrease in ast in the i / r - ip group when compared with the i / r group . alt and plasma il-1 was decreased in the control and i / r groups whereas plasma tnf- was decreased when compared with the i / r - ip group . tissue tnf- was increased compared with all the other groups , ie , control , t / r , and ip . table 2 shows the oxidative stress parameters , including mda , gsh , gssg , and nox . md and nox were increased and gsh and gssg were decreased in the i / r group when compared with controls . mda was decreased in the ip group when compared with the control group and increased when compared with the i / r group . gssg was increased in groups 1 and 2 , and nox was decreased compared with the i / r group and increased compared with the control group . in the ip - i / r group , mda and nox were decreased when compared with i / r , and gsh was increased as compared with the ip group and decreased when compared with the control group . table 3 shows that sod was increased significantly in the ip - i / r group when compared with the control , whereas gpx was decreased , but only gpx increased when compared with the i / r group , in which caspase-3 was decreased . ip ( group 2 ) showed significantly increased caspase-3 compared with the control , but a decrease in gpx , while sod showed a significant change in the ip group , the i / r group showed a significant decrease in gpx and an increase in caspase-3 compared to the control . table 4 shows that there was a significant increase in glycogen phosphorylase in the i / r group compared with the control group . there was a significant decrease in glycogen synthase in the i / r group as compared with the control group . glycogen synthase was increased in the i / r - ip group as compared with the i / r group , as shown in table 5 . there was a significant decrease in glycogen content in the i / r group compared with the control , and glycogen was significantly increased in the ir / pr group when compared with the i / r group ( table 6 ) . although the precise mechanisms by which ip reduces iri are not well understood , several factors have been reported to contribute to ip - mediated tissue protection.17 the protective effects of ip , a phenomenon by which a traumatic or stressful stimulus confers protection against subsequent injury , have been well documented in many organs , including the heart , brain , skeletal muscle , lung , intestine , kidney , retina , and endothelial cells.18 there is increasing evidence that cellular ischemic stressors activate protein kinase via g - protein - coupled receptor binding and membrane phospholipase activation.19 the signal transduction cascade for ip involves activation of protein kinase c , protein tyrosine kinase , and mitogen - activated protein kinase . however , it was found that protein kinase c inhibitors could attenuate the effects of ip induced by one cycle but not repetitive cycles in the heart . these data also suggest that repetitive ip may activate mechanisms other than the antioxidant system . we also examined its effect on the inflammatory response of i / r as exemplified by il-1 determination , in addition to its effects on the oxidant - antioxidant system.1921 increasing evidence has shown that proinflammatory cytokines and ros are both key mediators of liver iri.22 shortly after hepatic iri ( 16 hours ) , kupffer cells are activated and release proinflammatory cytokines , such as tnf- and il-1. these cytokines have a dual role : overexpression of tnf- and il-1 can induce more production of cytokines and granulocyte colony - stimulating factor , which enhances activation of kupffer cells and promotes infiltration of neutrophils into the microcirculation of the liver,23 thereby aggravating sterile hepatic inflammation after ischemia and reperfusion . on the other hand , tnf- and il-1 are indispensable for liver regeneration.24 measurement of mda levels is used widely as an indicator of lipid peroxidation . nitric oxide is also recognized as an important mediator of physiological and pathological processes in hepatic and renal iri.25 hepatic i / r can lead to damage and dysfunction ( apoptosis ) of liver parenchymal and sinusoidal cells . ip is extensively documented to reduce iri in a variety of organs including the liver,2628 and the caspase-3 enzyme is used as an indicator of apoptosis . this parameter was included in the present study to determine if ip can actually protect the liver from cell death . in this study , there was a significant increase in the serum activity of ast and alt in the i / r group when compared with corresponding values in the control group . this result were in agreement with those of wang et al28 and jaeschke and lemasters,29 who found that i / r resulted in a significant increase in ast and alt levels when compared with controls . ast and alt concentrations are commonly used as indirect biochemical indices of liver injury.28,29 studies have shown that increased ast and alt levels in iri probably result from cell membrane damage.30,31 on the other hand , the increase in ast and alt activity observed in the i / r group by lipid peroxidation leads to cytolysis , which is caused by oxygen free radicals formed during the reperfusion phase . there was a significant decrease in serum alt activity in the i / r - ip group when compared with corresponding values in the i / r group . these results are in agreement with those of romanque et al,32 who found that alt was strongly decreased in the ip - i / r group , with net reductions of 57% in serum alt level when compared with the i / r group . at the same time , kupffer cells and hepatocytes also generate ros , leading to direct damage of endothelial cells and hepatocytes . due to their important role , ros levels are tightly regulated through different pathways.33 the major regulators are ros scavengers that include sod , catalase , and glutathione peroxidase ( gsh - px ) . these ros scavengers are responsible for reducing ros inside tissues . another type of oxidative stress regulation is mediated by nitric oxide ( no ) , which is created by endothelial and inducible no synthases in the liver . no can regulate endothelial function , and its levels can affect blood flow in an organ . ros have been considered a major deleterious factor in reperfusion injury.34 in the present study , we found that liver i / r depleted glutathione stores in the liver and plasma . gsh is an important intracellular antioxidant that acts by directly scavenging ros and also by being a cofactor for gpx - catalyzed reactions that degrade hydrogen peroxide.35 depletion of gsh therefore renders cells susceptible to oxidative stress . in accordance with this , we found significant inhibition of gpx in the liver and plasma , resulting in excessive production of ros . this results in local oxidative stress on the liver and also a systemic oxidative state as indicated by increased levels of lipid peroxidation end products ( mda ) and decreased gssg . in this study , there was a significant increase in the hepatic activity of mda in the i / r group when compared with corresponding values in the control group . this finding is in agreement with that of wang et al,28 who found that the content of mda , a marker of liver oxidative injury , was significantly increased in the model group when compared with the control group . the results reported by yang et al36 show that mda levels in liver tissue were elevated significantly when treated with vehicle after brain i / r in rats , indicating that the function of the liver , although a remote organ , was damaged . lipid peroxidation is known to be responsible for cell membrane damage , and has been implicated in the pathogenesis of iri.22 accumulation of ros may easily overcome endogenous antioxidative systems , such as sod , catalase , gpx , and gsh , and because ros exist in relatively low concentrations in the liver , they have been proposed to be a contributory factor to cellular mechanisms of inflammation and iri.1,4 in the present study , it was found that the presented model of hepatic i / r was accompanied by a 254% increase in protein carbonyl content and a 37% decrease in hepatic gsh , with a net 481 enhanced protein carbonyl / gsh content ratio : sham - operated rats = 0.260.03 ( n=23 ) versus i / r animals = 1.510.27 ( n=6 ; p>0.0001 ) . this pro - oxidant state was significantly attenuated by the ip maneuver , as evidenced by total recovery of the protein carbonyl content and an 89% net reduction in gsh depletion , when differences between the i / r and sham - operated groups were compared with those between ip - treated rats with and without i / r ( p>0.05 ) . on one hand , no can induce cellular cytotoxicity and tissue injury via the peroxynitrite formation , protein tyrosine nitration , lipid peroxidation , dna damage , and proapoptotic effects included in iri.37 on the other hand , no may have a protective effect in vasodilatation , antiapoptotic action , inhibition of platelet plug formation , and reduction of the inflammatory response.38 thus , the cellular effects of no may depend on its concentration , site of release , and duration of action . the discrepancy in the previously recorded results might be due to different levels of no production associated with the degree or method of iri.39 however , there is evidence that ip decreased no levels significantly after three cycles of i / r.39 in contrast with this finding , group 2 ( i / r ) showed a slight decrease in this value , which may be attributed to different conditions of induction of i / r . sod catalyzes dysmutation of the superoxide anion to hydrogen peroxide and oxygen , but hydrogen peroxide still produces liver oxidative injury , and gpx further catalyzes the transformation of hydrogen peroxide to form water.40 i / r reduces liver antioxidant capacity , as evidenced by the downregulated activity of gpx . however , our study revealed that i / r treatment did not significantly change sod , implying that i / r with its oxidant metabolites decreased the antioxidant capacity of sod enzyme . previous research also showed that ip increased the expression and activity of antioxidant enzymes in the ischemic kidney and liver,41 which is in accordance with the present study , where ip decreased mda and gssg concentrations and avoided depletion of gsh , sod and gsh - px in the ischemic kidney . ip also decreased mda and increased gsh in the heart , with no significant change in the other parameters in rats exposed to renal i / r . increased gsh and decreased mda and gssg in the plasma of renal i / r rats our data demonstrate that exposure of the rat liver to an i / p maneuver for 3 hours before the i / r protocol significantly diminishes hepatocellular injury , suggesting the development of a second or delayed phase of protection against iri . this ip was characterized by development of transient oxidative stress of a considerably smaller magnitude than that elicited by i / r . the ip mechanisms involved in hepatic iri as investigated in our study suggest that the protective effects of ip against hepatic iri are related to their role in reducing tissue oxidative stress levels . ip may regulate the activity of sod , gsh - px , nos , and ip , and offer additive protection by increasing gsh - px activity . it may also decrease cellular injury and promote cell survival by suppressing release of cytokines . as reported , ip has a similar physiological and cellular protection mechanism : they have the same catalytic substrate adenosine ; they transport bioinformation through the phosphatidylinositol 3-kinase / akt pathway ; and they can decrease cytokines release.35 another contributory factor to parenchymal inflammation in iri is enhanced tnf- generation by activated kupffer cells.42,43 accordingly , a 15.3-fold increase above that of sham operated rats was observed for serum tnf- levels in i / r animals in the present study . our study also showed a high increase in plasma il-1 and an increase in the liver of i / r rats was shown in other studies . our studies also indicated that ip suppressed the tnf- response in plasma and oxidative stress induced by i / r , as evidenced by normalization of i / r - induced gsh depletion and protein oxidation in the ip - i / r group . we also demonstrated liver protection by ip to be related to recovery of cellular signaling functions modified by the i / r protocol . these findings were found by other researchers to help upregulation of nuclear factor kappa beta and downregulation of activator protein 1 ( ap-1 ) dna binding , with significant reduction in the ap-1/nuclear factor kappa beta dna binding ratio , which may afford liver protection by decreasing susceptibility to ros and tnf--induced liver injury . it was suggested that individual application of ip might reach the limit of decreasing cytokines release in rats . recent studies have hypothesized a role for tnf- and il-1 in liver regeneration.44 our data confirm that maintenance of tnf- and il-1 concentrations at a certain level might help recovery of hepatic function in the liver regeneration process . xanthine oxidase is capable of reducing molecular oxygen to both superoxide and hydrogen peroxide , and has been suggested to be the major source of ros metabolites generated during i / r . plasma xanthine oxidase activity was increased dramatically after liver and gut i / r.45 it has been shown that during i / r , sinusoidal cells die only via apoptosis while hepatocytes may die in both ways ( necrosis and apoptosis ) . in sinusoidal cells , apoptosis occurs earlier and at a higher level than in hepatocytes , but the differences in extent of apoptosis between these cells tend to be improved after a prolonged reperfusion period.15 the present results also demonstrate improvement in caspase-3 levels by ip . reduction of iri has been associated with decreased serum aminotransferase , a finding which has also been confirmed in human models , especially in a younger population,27 and it has been shown that ip protects the liver by inhibiting apoptosis of sinusoidal endothelial cells . liver glycogen is the first and immediate source of glucose for the maintenance of blood glucose levels . in the liver , the glucose-6-phosphate generated from degradation of glycogen is hydrolyzed to glucose by glucose 6-phosphatase , an enzyme present only in the liver and kidneys . glycogen degradation thus provides a readily mobilized source of blood glucose.46 the principal enzymes controlling glycogen metabolism , ie , glycogen phosphorylase and glycogen synthase , are regulated by allosteric mechanisms and covalent modifications due to reversible phosphorylation and dephosphorylation of proteins in response to hormone action . in the present study , there was a significant decrease in hepatic glycogen activity in the i / r group as compared with corresponding values in the control group . on the other hand , there was a significant increase in hepatic glycogen activity in the i / r - ip group as compared with corresponding values in the i / r group . these results are in agreement with those of peralta et al,35 who found that the glycogen concentration decreased as a function of duration of ischemia . however , glycogen levels were always higher in preconditioned livers.47 glycogen concentration decreased as a function of duration of ischemia ; however , glycogen levels were always higher in preconditioned livers.46 in summary , the present study shows that ip can protect sinusoidal endothelial cells as well as hepatocytes during liver iri , and the mechanism partly involves modulation of the imbalance of the endogenous oxidant - antioxidant system in the organism . this may suggest a potential role for antioxidant enzymes in the management of iri , but further studies are needed regarding their injury preventive effects .

ischemia - reperfusion ( i / r ) injury is a multifactorial process that affects graft function after liver transplantation . an understanding of the mechanisms involved in i / r injury is essential for the design of therapeutic strategies to improve the outcome of liver transplantation . the generation of reactive oxygen species subsequent to reoxygenation inflicts tissue damage and initiates a cascade of deleterious cellular responses , leading to inflammation , cell death , and ultimate organ failure . increasing experimental evidence has suggested that kupffer cells and t - cells mediate activation of neutrophil inflammatory responses . activated neutrophils infiltrate the injured liver in parallel with increased expression of adhesion molecules on endothelial cells . the heme oxygenase system is among the most critical of the cytoprotective mechanisms activated during cellular stress , exerting antioxidant and anti - inflammatory functions , modulating the cell cycle , and maintaining the microcirculation . finally , the activation of toll - like receptors on kupffer cells may play a fundamental role in exploring new therapeutic strategies based on the concept that hepatic i / r injury represents a case for host innate immunity . in the present study , there was a significant decrease in hepatic activity of glycogen in the i / r group as compared with corresponding values in the control group . on the other hand , there was a significant increase in the hepatic activity of glycogen in the i / r - ip ( ischemic preconditioning ) group as compared with corresponding values in the i / r group .

N.M. woman billed $5,000 after cops order warrantless, ‘redundant’ cavity searches By Scott Kaufman Friday, December 20, 2013 9:59 EDT An unnamed 54-year-old New Mexico woman is suing the El Paso County Hospital District, the University Medical Center of El Paso, and four United States Customs and Border Patrol agents for what her lawsuit stipulates were “multiple, redundant and increasingly intrusive searches.” According to court documents, “Jane Doe” was returning to the United States from Mexico when, at a border station in El Paso, a drug-sniffing dog indicated that she may have been in possession of illicit substances. Then, over “the next six hours, Defendants subjected Ms. Doe to a series of highly invasive searches, any one of which would have been humiliating and demeaning,” all of which was done without the benefit of a warrant. Government agents first subjected her to a strip-search. “Having found nothing,” the suit contends, “Defendants next shackled Ms. Doe to an examining table and inserted a speculum into her vagina, performed a rectal exam on her, and conducted a bimanual cavity search of her vagina.” “Ms. Doe was mortified,” according the suit. “Defendants did not even have the decency to close the door to the examining room so that Ms. Doe would not also be subjected to being observed by passersby as she endured a forced gynecological exam.” Still having found nothing, they “subjected her to an observed bowel movement.” When that observation yielded no evidence of drugs, they X-rayed her. When that also failed to produce any evidence of drugs, they subjected her to a CT (computed tomography) scan and, again, found no evidence of drugs. At the end of this ordeal, she was released without any charge. However, despite the fact that these invasive tests were done without her consent or a warrant, she later received a bill from the University Medical Center of El Paso for $5,000. “What is truly frightening about this incident is that it could have happened to anyone,” Laura Schauer Ives, the legal director for the American Civil Liberties Union of New Mexico, told the Associated Press. “The fact that this happened to a 54-year-old woman should outrage anyone. She did ask to talk to an attorney and she did ask for a warrant. I don’t know what guarantees there are to our rights other than a lawsuit like this one that hold the government agencies responsible.” ["Police Officer Arresting A Woman With Handcuffs" on Shutterstock] ||||| These crawls are part of an effort to archive pages as they are created and archive the pages that they refer to. That way, as the pages that are referenced are changed or taken from the web, a link to the version that was live when the page was written will be preserved.Then the Internet Archive hopes that references to these archived pages will be put in place of a link that would be otherwise be broken, or a companion link to allow people to see what was originally intended by a page's authors.The goal is to fix all broken links on the web . Crawls of supported "No More 404" sites. ||||| In a case eerily similar to David Eckert's humiliating ordeal at the hands of cops in Deming, New Mexico, a federal lawsuit charges Customs and Border Protection agents with subjecting a U.S. citizen to six hours of degrading and fruitless body cavity searches based on an alleged alert by a drug-sniffing dog. The lawsuit, filed yesterday by the ACLU chapters in Texas and New Mexico, says the plaintiff, a 54-year-old New Mexico resident identified in the complaint as Jane Doe, was crossing the bridge between Ciudad Juarez, Mexico, and El Paso after visiting a family friend last December when she was chosen at random for "additional screening." This "secondary inspection" involved a pat-down during which an agent "inserted her finger in the crevice of Ms. Doe's buttocks"—a rather startling incursion inasmuch as the agents at this point had no basis to suspect that the woman was carrying contraband. But they were just getting started. The agents instructed the plaintiff to stand in line with other people who had been selected for additional screening and walked a dog past her. According to the lawsuit, the dog handler "hit the ground by her feet, but did not hit the ground by any of the others in the line," and "the dog responded by lunging onto Ms. Doe and landing its front paws on her torso." Why did the dog do that? "Because Ms. Doe did not possess any contraband," says the complaint, "the dog either did not alert or the response was not a proper alert." Yet this possibly manufactured and in any event erroneous alert was the basis for all that followed. First the agents strip-searched the plaintiff, examining her anus and vagina with a flashlight. Finding nothing, they took her to the University Medical Center of El Paso, where they forced her to take a laxative and produce a bowel movement in their presence. Again they found no evidence of contraband. At this point one of their accomplices, a physician named Christopher Cabanillas, ordered an X-ray, which likewise found nothing suspicious. Then the plaintiff "endured a forced gynecological exam" and rectal probing at the hands of another doctor, Michael Parsa. Still nothing. Finally, Cabanillas ordered a CT scan of the plaintiff's abdomen and pelvis, which found no sign of illegal drugs. "After the CT scan," the complaint says, "a CBP [Customs and Border Patrol] agent presented Ms. Doe with a choice: she could either sign a medical consent form, despite the fact that she had not consented, in which case CBP would pay for the cost of the searches; or if she refused to sign the consent form, she would be billed for the cost of the searches." She refused, and later the hospital sent her a bill for $5,000, apparently the going rate for sexual assault and gratuitous radiological bombardment. David Eckert, you may recall, also got a bill (in his case for about $6,000) after undergoing a similar exploration of his orifices and plumbing, which likewise continued, becoming increasingly invasive, precisely because the cops were not finding any evidence to substantiate their suspicions. And while the police in his case did obtain a warrant, the main basis for it was a dog's purported alert, which in Jane Doe's case seems to have been the only evidence that she was smuggling drugs. Although such alerts are frequently wrong and can easily be faked, the Supreme Court has said they qualify as probable cause for a search as long as the dog is properly trained. The burden of showing a dog is not properly trained lies with the person challenging the search. Aside from the dangers of putting too much faith in drug-detecting dogs, this case, like Eckert's, illustrates the appalling complicity of doctors in waging the war on drugs, even when it involves utterly unethical participation in dehumanizing pseudomedical procedures performed on involuntary and audibly protesting "patients." In addition to Border Patrol agents, the lawsuit names the hospital, Cabanillas, and Parsa. Lest you think the criminal malpractice described in this complaint is an aberration, the ACLU offers evidence that it is in fact commonplace: During the car ride to the Medical Center, Ms. Doe asked if the agents had awarrant. One of them responded that they did not need a warrant.... Medical Center policy L-13 on searches by hospital personnel does not permit an invasion of a person's body for purposes of a search without either consent or a search warrant. However, in practice, the Medical Center staff and CBP agents routinely conduct invasive cavity searches without a warrant, consent or sufficient suspicion to justify the searches. When Ms. Doe expressed dismay about the unreasonable searches she suffered, a Medical Center employee responded that these procedures were routinely followed when an individual is brought in by CBP agents. The employee also told Ms. Doe that what happened to her was not invasive. This kind of abuse tends to draw attention only when the victim is "innocent," meaning he or she is not in fact smuggling drugs. But how can any society call itself civilized when it allows human beings to be treated this way in the name of locating arbitrarily proscribed substances? Having arrogated to itself the authority to regulate what people put into their own bodies, the government ends up forcibly delving into those bodies in search of the chemicals it has anathematized. To enforce politicians' pharmacological prejudices, the government's agents and their medical accomplices become kidnappers and rapists. There is nothing noble or decent about this immoral crusade, and anyone associated with it ought to be ashamed of himself.

– A 54-year-old New Mexico woman is suing US customs and a hospital after an escalating series of drug searches that took six hours and yielded no sign of drugs—only a $5,000 hospital bill for her trouble. Some details, as rounded up by Raw Story, Reason, and the AP: The unidentified woman got stopped returning from Mexico at the El Paso border crossing, when a drug-sniffing dog got agitated. She underwent a strip-search and cavity searches, according to her lawsuit. Agents didn't even shut the door, it adds. When those turned up nothing, she got taken to the University Medical Center of El Paso, where doctors gave her laxatives and observed a bowel movement. Still no sign of drugs. After that, she got X-rayed and then underwent a CT scan, at which point authorities released her without charges. The medical center later sent her a $5,000 bill for its tests. The ACLU has taken up the case, and its complaint is here. "The failed drug war and militarized border region have created an environment in which law enforcement officials increasingly inflict extreme and illegal searches on innocent Americans," says a local legal director for the group.

SECTION 1. SHORT TITLE. This Act may be cited as the ``Family Farm and Small Business Tax Relief Act of 2009''. SEC. 2. EXTENSION OF 2009 ESTATE AND GIFT TAX LEVELS. (a) EGTRRA Sunset Not To Apply.--Section 901 of the Economic Growth and Tax Relief Reconciliation Act of 2001 shall not apply to title V of such Act (other than subtitles A and E, and sections 511(d) and 521(b)(2), thereof). (b) $3,500,000 Applicable Exclusion Amount.-- (1) In general.--Subsection (c) of section 2010 of the Internal Revenue Code of 1986 is amended by striking all that follows ``the applicable exclusion amount'' and inserting ``. For purposes of the preceding sentence, the applicable exclusion amount is $3,500,000.''. (2) Inflation adjustment.--Section 2010 of such Code is amended by redesignating subsection (d) as subsection (e) and by inserting after subsection (c) the following new subsection: ``(d) Cost-of-Living Adjustment.--In the case of any decedent dying in a calendar year after 2011, the $3,500,000 amount in subsection (c) shall be increased by an amount equal to-- ``(1) such amount, multiplied by ``(2) the cost-of-living adjustment determined under section 1(f)(3) for such calendar year by substituting `calendar year 2010' for `calendar year 1992' in subparagraph (B) thereof. If any amount as adjusted under the preceding sentence is not a multiple of $10,000, such amount shall be rounded to the nearest multiple of $10,000.''. (c) 45 Percent Maximum Rate.--The table in paragraph (1) of section 2001(c) of such Code is amended by striking the last 3 items and inserting the following new item: ``Over $1,500,000............................ $555,800, plus 45 percent of the excess of such amount over $1,500,000.''. (d) Effective Date.--The amendments made by this section shall apply to estates of decedents dying, and gifts made, after December 31, 2010. SEC. 3. RESTORATION OF, AND INCREASE IN, DEDUCTION FOR FAMILY-OWNED BUSINESS INTERESTS. (a) Restoration.--Subsection (j) of section 2057 (relating to termination) is amended to read as follows: ``(j) Application of Section.--This section-- ``(1) shall not apply to estates of decedents dying after December 31, 2003, and before January 1, 2011, but ``(2) shall apply to estates of decedents dying after December 31, 2010.''. (b) Increase.-- (1) In general.--Subsection (a) of section 2057 is amended-- (A) by striking ``$675,000'' in paragraph (2) and inserting ``$8,000,000'', and (B) by striking paragraph (3). (2) Cost-of-living adjustment.--Subsection (a) of section 2057 is amended by adding at the end the following new paragraph: ``(3) Cost-of-living adjustment.--In the case of any decedent dying in a calendar year after 2011, the $8,000,000 amount in paragraph (2) shall be increased by an amount equal to-- ``(A) such dollar amount, multiplied by ``(B) the cost-of-living adjustment determined under section 1(f)(3) for such calendar year by substituting `calendar year 2010' for `calendar year 1992' in subparagraph (B) thereof. If any amount as adjusted under the preceding sentence is not a multiple of $10,000, such amount shall be rounded to the nearest multiple of $10,000.''. (c) Effective Date.--The amendments made by this section shall apply to estates of decedents dying after December 31, 2010. SEC. 4. EXCLUSION FROM GROSS ESTATE FOR CERTAIN FARMLAND SO LONG AS FARMLAND USE CONTINUES. (a) In General.--Part III of subchapter A of chapter 11 of the Internal Revenue Code of 1986 (relating to gross estate) is amended by inserting after section 2033 the following new section: ``SEC. 2033A. EXCLUSION OF CERTAIN FARMLAND SO LONG AS USE AS FARMLAND CONTINUES. ``(a) In General.--In the case of an estate of a decedent to which this section applies, if the executor makes the election described in subsection (f), the value of the gross estate shall not include the adjusted value of qualified farmland included in the estate. ``(b) Estates to Which Section Applies.--This section shall apply to an estate if-- ``(1) the decedent was (at the date of the decedent's death) a citizen or resident of the United States, and ``(2) during the 8-year period ending on the date of the decedent's death there have been periods aggregating 5 years or more during which-- ``(A) the qualified farmland was owned by the decedent or a member of the decedent's family, and ``(B) there was material participation (within the meaning of section 2032A(e)(6)) by the decedent or a member of the decedent's family in the operation of such farmland, except that `material participation' shall also include any rental of real estate and related property between the estate of the decedent or any successor thereto and any tenant so long as the tenant uses the real estate and related property to produce agricultural or horticultural commodities, including but not limited to livestock, bees, poultry, orchards and woodlands, timber and fur-bearing animals and wildlife on such farmland. Rules similar to the rules of paragraphs (4) and (5) of section 2032A(b) shall apply for purposes of subparagraph (B). ``(c) Definitions and Special Rule.--For purposes of this section-- ``(1) Qualified farmland.--The term `qualified farmland' means any real property or other property related to the farm operation-- ``(A) which is located in the United States, ``(B) which is used as a farm for farming purposes, and ``(C) which was acquired from or passed from the decedent to a qualified heir of the decedent and which, on the date of the decedent's death, was being so used by the decedent or a member of the decedent's family. ``(2) Member of family.--A member of a family, with respect to any individual, means-- ``(A) a member of the family (as defined by section 2031A(e)(2)), and ``(B) includes-- ``(i) a lineal descendant of any spouse described in subparagraph (D) of section 2032A(e)(2), ``(ii) a lineal descendant of a sibling of a parent of such individual, ``(iii) a spouse of any lineal descendant described in clause (ii), and ``(iv) a lineal descendant of a spouses described in clause (iii). ``(3) Adjusted value.--The term `adjusted value' means the value of farmland for purposes of this chapter (determined without regard to this section), reduced by the amount deductible under paragraph (3) or (4) of section 2053(a). ``(4) Other terms.--Any other term used in this section which is also used in section 2032A shall have the same meaning given such term by section 2032A. ``(d) Tax Treatment of Dispositions and Failures To Use for Farming Purposes.-- ``(1) Imposition of recapture tax.--If, at any time after the decedent's death-- ``(A) the qualified heir disposes of any interest in qualified farmland (other than by a disposition to a member of his family), or ``(B) the qualified heir ceases to use the real property which was acquired (or passed) from the decedent as a farm for farming purposes, then there is hereby imposed a recapture tax on such disposition or cessation of use. ``(2) Amount of recapture tax.-- ``(A) In general.--The amount of the tax imposed by paragraph (1) shall be the excess of-- ``(i) the tax which would have been imposed by section 2001 on the estate of the decedent but determined as if such estate included the interest in qualified farmland described in paragraph (1) which was so disposed of or ceased to be so used, reduced by the credits allowable against such tax, over ``(ii) the tax imposed by section 2001 on the estate of the decedent, reduced by such credits. For purposes of this paragraph, the value of the interest in qualified farmland specified in subparagraph (A) shall be the adjusted value of such interest as of the date of the disposition or cessation of such interest described in paragraph (1). ``(B) $8,000,000 exclusion amount.--For purposes of subparagraph (A), the adjusted value of such interest shall be reduced by an amount equal to-- ``(i) $8,000,000, reduced (but not below zero) by ``(ii) an amount equal to the amount by which the adjusted value of all other interests in such qualified farmland has been reduced previously by reason of this subparagraph. ``(3) Regulations.--The Secretary may prescribe such regulations as may be necessary or appropriate to carry out this subsection, including regulations requiring record keeping and information reporting, except that the Secretary may not impose a lien on the estate of the decedent or qualified farmland for such purposes. ``(e) Application of Other Rules.--Rules similar to the rules of subsections (e) (other than paragraph (13) thereof), (f), (g), (h), and (i) of section 2032A shall apply for purposes of this section. ``(f) Election.--The election under this subsection shall be made on or before the due date (including extensions) for filing the return of tax imposed by section 2001 and shall be made on such return.''. (b) Clerical Amendment.--The table of sections for part III of subchapter A of chapter 11 of such Code is amended by inserting after the item relating to section 2033 the following new item: ``Sec. 2033A. Exclusion of certain farmland so long as use as farmland continues.''. (c) Effective Date.--The amendments made by this section shall apply to estates of decedents dying after the date of the enactment of this Act.

Family Farm and Small Business Tax Relief Act of 2009 - Extends the estate and gift tax rates in effect in 2009 by eliminating the general terminating date (i.e., December 31, 2010) in the Economic Growth and Tax Relief Reconciliation Act of 2001 (EGTRRA) applicable to such rates. Amends the Internal Revenue Code to: (1) establish a permanent $3.5 million estate tax exclusion (adjusted for inflation) and a maximum estate and gift tax rate of 45% after 2010; (2) restore after 2010 the estate tax deduction for family-owned business interests and increase the amount of such deduction to $8 million (adjusted annually for inflation); and (3) exclude from the gross estate of a decedent the value of farmland used as a farm for farming purposes.

wandering spleen is an unusual condition characterized by the absence or maldevelopment of one or all of the ligaments securing the spleen in its normal position in the left upper abdomen . pedicular tortion with a complete vascular disruption is a rare but known potential complication of this mostly congenital disorder . spontaneous hemoperitoneum with acute abdomen however , is a life threatening situation that has not been adequately reported in the adult literature . a forty four year old man presented to the emergency department with an acutely distended and rigid abdomen . an enlarged pelvic spleen and free intraperitoneal fluid consistent with blood were seen on a ct scan . the patient was promptly taken for an exploratory laparotomy where a large rush of blood was encountered upon entering the abdomen . a volvulus of the splenic pedicle with an infarcted spleen was found mandating a splenectomy . abnormally located spleen , splenomegaly , and finding of hemoperitoneum are highly suggestive of wandering spleen with tortioned pedicle . despite its life threatening presentation , immediate laparotomy and splenectomy invariably result in good outcome . wandering spleen is an unusual condition characterized by an increased splenic mobility related to laxity or abscence of the splenogastric , splenorenal , or splenocolic ligaments . the first description of wandering spleen is credited to van horne during an autopsy in 1667 . it can occur at all ages but more commonly seen in reproductive aged women raising a suspicion that the splenic ligamentous laxity might be related to the hormonal effects of pregnancy . this condition may present as an asymptomatic abdominal / pelvic mass , intermittent intestinal obstruction , or acute abdominal pain . the authors report an unusual case of wandering spleen with pedicular tortion on a middle aged man presenting with large hemoperitoneum and abnormally located enlarged spleen . a forty four year old man presented to the geisinger clinic emergency department for an evaluation of worsening abdominal pain associated with low grade fever , nausea and vomiting that had started one day prior to admission . the patient denied prior abdominal complaints , recent trauma , or changes in bowel habits . on the physical examination , he appeared to be anxious , mildy tachypneic and pale with heart rate of 132 beats per minute . an abdominal palpation showed moderate distention , diffuse rigidity with guarding , rebound tenderness , and hypoactive bowel sounds . complete blood count showed a leukocytosis of 22.5 mg / dl , bandemia of 14% , hemoglobin of 9.6 mg / dl ( baseline of 15 mg / dl ) . liver function tests , pancreatic enzymes , and lactic acid were all within normal limits . a ct scan showed an abnormally located spleen in the lower pelvis measured 15.7 10 9.2 cm ( figs . 1 and 2 ) . the splenic artery descended inferiorly through the midabdomen and was markedly tortuous , suggesting a pedicular volvulus . the splenic parenchyma failed to enhance following intravenous contrast injection as what typically would have been seen in a normal spleen . the body and tail of the pancreas appeared to be coiled around the splenic vessels ( fig . no free air was identified . the enlarged spleen located in the pelvis with hemoperitoneum . p = pancreas exploratory laparotomy was promptly performed revealing a large rush of blood upon entering the peritoneal cavity . once the midline incision was advanced inferiorly , a large mobile spleen was found in the pelvis which was easily brought up into the operative field . there was a volvulus of the splenic pedicle and distal pancreas . approximately one liter of blood was suctioned and the abdomen was thoroughly irrigated using three liters of normal saline . postoperatively , the patient was transferred to the postoperative care unit and medical - surgical floor in a stable condition . during embriogenesis , the spleen begins its development in the fifth week of gestation from the mesenchymal cells in the dorsal mesogastrium . this dorsal mesogastrium is also responsible for the formation of the peritoneum , greater omentum and peritoneal folds including the major splenic ligaments . it was proposed that abnormal laxity and elongated hilum allow the spleen to freely migrate and become hypermobile in the abdomen . the incidence of wandering spleen is 15 times greater in women compared to that in men , especially in women between 20 and 40 years of age suggesting the role hormonal factor . splenomegaly from any causes may predispose to the wandering spleen , however by itself is unlikely to play a significant role since there is no increased incidence of wandering spleen in geographic regions with endemic splenomegaly from infectious origin . . sixty percent of patients experience abdominal pain or discomfort , while the remainders are asymptomatic . even though the pain is mostly acute indicating an acute torsion , volvulus of the spleen resulting in splenic vessels obstruction and parenchymal infarction may also be chronic and intermittent from repeated tortion - detortion . when pancreatic tail is involved , a whorl of normal appearing pancreatic and fat tissues at the medial border of the displaced spleen may be seen . the presence of an abdominal or pelvic mass , abnormally located bowel loops , findings of gastrointestinal obstruction , and elevated left kidney are sometimes seen on plain film . laboratory findings of leukocytosis , thrombocytopenia , and anemia may be present however they are nonspecific as well as nondiagnostic . a unique presentation of acute gastric hemorrhage secondary to wandering spleen has also been reported by angeras et al . in that case , a pedicular tortion resulted in impaired blood return via the splenic vein . as the consequence , collateral circulations then built through the short gastric vessels leading to a formation of isolated gastric varices and ultimately bleeding from the stomach fundus . another unusual presentation of hypermobile spleen which resulted in recurrent episodes of acute pancreatitis was reported by choi yh et al . in this case , the recurrent pancreatitis was attributable to a counterclockwise rotation of the pancreatic tail resulting in intermittent kinking / obstruction of the pancreatic duct which then subsequently led to mechanical pancreatitis . watchful management has been found to lead to splenic torsion and infarction in more than half of the patients , therefore an elective operation is recommended . the splenopexy and splenectomy can be performed either with open or laparoscopic approach . in the case of open splenectomy , access to the left upper quadrant can be obtained either through a midline or left subcostal incision . splenic detortion and hilar transection must be performed carefully to avoid rupture / bleeding and injury to the pancreatic tail respectively . majority of patients however were successfully managed using conservative approach which entail bowel rest with or without total parenteral nutrition until resolution of their hyperlipasemia or fistulae . other potential complications include postoperative hemorrhage requiring reoperation , subphrenic abscess , and incisional wound complications . nowadays , abdominal drain is not used routinely anymore after a splenectomy due to the increased incidence of intraabdominal infection / abscess . in children , splenic preservation is always preferred in order to minimize the risk of infection , especially with encapsulated organisms . in this young population , the risk of developing postsplenectomy septicemia is 4% , with fatality rate of 1.8% . in adults , they are slightly less , 1.9% and 1.1% respectively . the more rarely seen overwhelming postsplenectomy sepsis however , has a fatality rate of 60% . several authors have therefore described conservative management of this condition with various techniques of laparoscopic splenopexy . it has been well known that the laparoscopic approach offers benefits such as shorter hospital stay , less immune system attennuation , earlier return of bowel function and quicker postoperative recovery . the laparoscopic splenopexy can be performed via creation of an extra / retroperitoneal pocket to house the spleen , direct suture fixation of the splenic hilum to the splenic bed , colonic displacement in front of the spleen followed by a gastropexy to the anterior abdominal wall , or creation of an intraperitoneal pocket using absorbable mesh and omentum[1217 ] . all patients should receive pneumococcus , meningococcus and hemophilus influenzae vaccines in the case of splenectomy . wandering spleen is a rare entity that should be considered in patients presenting with acute abdomen and an abnormal palpable mass . the risks and benefits of various treatment options should be discussed and tailored to the individual patients .

context : wandering spleen is an unusual condition characterized by the absence or maldevelopment of one or all of the ligaments securing the spleen in its normal position in the left upper abdomen . pedicular tortion with a complete vascular disruption is a rare but known potential complication of this mostly congenital disorder . spontaneous hemoperitoneum with acute abdomen however , is a life threatening situation that has not been adequately reported in the adult literature.case report : a forty four year old man presented to the emergency department with an acutely distended and rigid abdomen . his past medical history was only significant for mild mental retardation . the patient denies prior abdominal operation or recent trauma . on initial examination , he appeared to be anxious , pale , and tachycardic . fullness in the midpelvic region was easily appreciated on palpation . an enlarged pelvic spleen and free intraperitoneal fluid consistent with blood were seen on a ct scan . the patient was promptly taken for an exploratory laparotomy where a large rush of blood was encountered upon entering the abdomen . a volvulus of the splenic pedicle with an infarcted spleen was found mandating a splenectomy.conclusions:abnormally located spleen , splenomegaly , and finding of hemoperitoneum are highly suggestive of wandering spleen with tortioned pedicle . despite its life threatening presentation , immediate laparotomy and splenectomy invariably result in good outcome .

during the last few years the development of photovoltaic energy has flourished in developing countries with both multi - megawatt power plants and micro installations . however , the scarcity of long - term , reliable solar irradiation data from pyranometers in many of these countries makes it necessary to estimate solar irradiation from other meteorological variables or satellite photographs @xcite . in such cases , models need to be validated via nearby pyranometer records , since they lack spatial generalization . thus , in some regions in which there are no pyranometers nearby these models are ruled out as an option and irradiation data must be obtained from satellite estimates . although satellite - derived irradiation databases such as nasa s surface meteorology and solar energy ( sse ) , the national renewable energy laboratory ( nrel ) , inpe , soda and the climate monitoring satellite application facility ( cm saf ) provide wide spatial coverage , only nasa and some cm saf climate data sets give global coverage , albeit at a reduced spatial resolution ( table [ tab : databases ] ) . .summary of solar irradiation databases [ cols="<,<,<,<,<,<",options="header " , ] the higher mae recorded in station locations in cm saf and _ downscaling without ked _ is also explained in the irradiation maps shown in figures [ fig : cmsaf ] and [ fig : ghinoked ] . the @xmath0 is lowered too far in certain regions of the area studied with _ downscaling without ked _ compared to @xmath1 , which is also shown in figure [ fig : spplot ] . the intrapixel variability due to the downscaling procedure is indicative of the importance of the topography as an attenuator of solar irrradiation . as a result , this zonal variability is higher in pixels with complex topographies and downscaling is more useful . figure [ fig : diffkedcmsaf ] shows the relative difference between downscaling with ked and cm saf . as might be deduced , cm saf over - estimates ghi in this region by between 11 and 22% . figures [ fig : zonal ] and [ fig : density ] display the standard deviations of the downscaled maps within each cell of the original cm saf raster ( 0.03x0.03@xmath2 ) . the ` zonal ` function from the ` raster ` library permits this calculation , explaining the intrinsic variability of solar radiation within gross resolution pixels . consequently , in those pixels with higher standard deviations there will be greater variability . figure [ fig : density ] shows how the ked method smooths the deviation within pixels and also the range of solar irradiation in the region ( figures [ fig : ghinoked ] and [ fig : ghiked ] ) . and @xmath3 related to @xmath3,scaledwidth=90.0% ] ) between downscaling without ked and with ked.,scaledwidth=90.0% ] a methodology for downscaling solar irradiation is described and presented using ` r ` software . this methodology is useful for increasing the accuracy and spatial resolution of gross resolution satellite - estimates of solar irradiation . it has been proved that areas whose topography is complex show greater differences with the original gross resolution data as a consequence of horizon blocking and lower sky - view factors , so downscaling is highly recommended in these areas . _ kriging with external drift _ with the ` gstat ` package has proved very useful in downscaling solar irradiation when on - ground registers are available and an explanatory variable is provided . this methodology is implemented as an example in the region of la rioja in northern spain , and striking reductions of 25.5% and 27.4% in mae and rmse are obtained compared to the original gross resolution database . the high repeatability of this methodology and the reduction in errors obtained might be also very useful in the downscaling of meteorological variables other than solar irradiation . the source code is available at https://github.com/edmansolar/downscaling . the results discussed in this paper were obtained in a ` r ` session with these characteristics : * r version 2.15.2 ( 2012 - 10 - 26 ) , ` x86_64-apple - darwin9.8.0 ` * locale : ` es_es.utf-8/es_es.utf-8/es_es.utf-8/c / es_es.utf-8/es_es.utf-8 ` * base packages : ` base ` , ` datasets ` , ` graphics ` , ` grdevices ` , ` grid ` , ` methods ` , ` parallel ` , ` stats`,`utils ` * other packages : ` foreign ` 0.8 - 51 , ` gstat ` 1.0 - 16 , ` hexbin ` 1.26.0 , ` lattice ` 0.20 - 15 , ` latticeextra ` 0.6 - 19 , ` maptools ` 0.8 - 14 , ` raster ` 2.1 - 16 , ` rastervis ` 0.20 - 01 , ` rcolorbrewer ` 1.0 - 5 , ` rgdal ` 0.8 - 01 , ` solar ` 0.33 , sp 1.0 - 8 , ` zoo ` 1.7 - 9 * loaded via a namespace ( and not attached ) : ` intervals ` 0.14.0 , ` spacetime ` 1.0 - 4 , ` tools ` 2.15.2 , ` xts ` 0.9 - 3 we are indebted to the university of la rioja ( fellowship fpi2012 ) and the research institute of la rioja ( ier ) for funding parts of this research . husain alsamamra , jose antonio ruiz - arias , david pozo - vzquez , and joaquin tovar - pescador . a comparative study of ordinary and residual kriging techniques for mapping global solar radiation over southern spain . _ agricultural and forest meteorology _ , 1490 ( 8):0 1343 1357 , 2009 . fernando antonanzas - torres , federico caizares , and oscar perpin . comparative assessment of global irradiation from a satellite estimate model ( cm saf ) and on - ground measurements ( siar ) : a spanish case study . _ renewable and sustainable energy reviews _ , 21:0 248261 , 2013 . batlles , j.l . bosch , j. tovar - pescador , m. martnez - durbn , r. ortega , and i. miralles . determination of atmospheric parameters to estimate global radiation in areas of complex topography : generation of global irradiation map . _ energy conversion and management _ , 490 ( 2):0 336 345 , 2008 . j. corripio . vectorial algebra algorithms for calculating terrain parameters from dems and solar radiation modelling in mountainous terrain . _ international journal of geographical information science _ , 17:0 123 , 2003 . edzer pebesma and benedikt graeler . _ ` gstat ` : spatial and spatio - temporal geostatistical modelling , prediction and simulation _ , 2013 . url http://cran.r-project.org/package=gstat . r package version 1.0 - 16 . richard perez , robert seals , ronald stewart , antoine zelenka , and vicente estrada - cajigal . using satellite - derived insolation data for the site / time specific simulation of solar energy systems . _ solar energy _ , 530 ( 6):0 491 495 , 1994 . r. posselt , r. muller , j. trentmann , and r. stockli . meteosat ( mviri ) solar surface irradiance and effective cloud albedo climate data sets . the cm saf validation report . technical report , the eumetsat network of satellite application facilities , 2011 . r. posselt , r.w . mueller , r. stckli , and j. trentmann . remote sensing of solar surface radiation for climate monitoring the cm - saf retrieval in international comparison . _ remote sensing of environment _ , 1180 ( 0):0 186 198 , 2012 . jos a. ruiz - arias , tom cebecauer , joaqun tovar - pescador , and marcel ri . spatial disaggregation of satellite - derived irradiance using a high - resolution digital elevation model . _ solar energy _ , 840 ( 9):0 1644 1657 , 2010 . j. schulz , p. albert , h .- d . behr , d. caprion , h. deneke , s. dewitte , b. drr , p. fuchs , a. gratzki , p. hechler , r. hollmann , s. johnston , k .- karlsson , t. manninen , r. mller , m. reuter , a. riihel , r. roebeling , n. selbach , a. tetzlaff , w. thomas , m. werscheck , e. wolters , and a. zelenka . operational climate monitoring from space : the eumetsat satellite application facility on climate monitoring ( cm - saf ) . _ atmospheric chemistry and physics _ , 90 ( 5):0 16871709 , 2009 .

a methodology for downscaling solar irradiation from satellite - derived databases is described using ` r ` software . different packages such as ` raster ` , ` parallel ` , ` solar ` , ` gstat ` , ` sp ` and ` rastervis ` are considered in this study for improving solar resource estimation in areas with complex topography , in which downscaling is a very useful tool for reducing inherent deviations in satellite - derived irradiation databases , which lack of high global spatial resolution . a topographical analysis of horizon blocking and sky - view is developed with a digital elevation model to determine what fraction of hourly solar irradiation reaches the earth s surface . eventually , kriging with external drift is applied for a better estimation of solar irradiation throughout the region analyzed . this methodology has been implemented as an example within the region of la rioja in northern spain , and the mean absolute error found is a striking 25.5% lower than with the original database . * keywords : * solar irradiation , r , ` raster ` , ` solar ` , digital elevation model , shade analysis , downscaling .

unilateral movement was continuous , choreoathetotic , purposeless , non - stereotyped , and involved the face ( twitching ) and upper and lower extremities . the movement was distressful to the patient and interfered with her activities of daily living and gait , causing recurrent falls . she had poorly controlled diabetes for approximately 20 years , and was maintained on oral hypoglycemic agents . she was not on hormone replacement therapy or any other medications to which these symptoms could be attributed . there was no family history of movement disorders , and no clinical features suggestive of connective tissue diseases . apart from the hemichorea involving the left side of the face and upper and lower extremities , her neurological examination was unremarkable ; with normal higher mental function , and normal cranial and sensory nerve examination . on admission , she was hyperglycemic with a random serum glucose of 30.3 mmol / l , ( normal level < 6.5 mmol / l ) ; and her glycosylated hemoglobin was 13.5% , normal level=4 - 6% . mmol / l , ( normal level=135 - 145 mmol / l ) , but other electrolytes were normal . her blood count , coagulation profile , liver function tests , vitamin b12 , and thyroid - stimulating hormone were all within normal . lipid profile showed dyslipidemia ( cholesterol 9.81 mmol / l , triglycerides 4.61 mmol / l , high - density lipoprotein 1.1 mmol / l , and low - density lipoprotein 6.61 mmol / l ) . further workup reinforced the evidence of poor diabetic control ; her ophthalmologic examination revealed moderate to severe nonproliferative diabetic retinopathy , and her protein to creatinine ratio was 2000 . non - enhanced brain mri ( figure 1 ) was obtained the next day and demonstrated an area of hyperintensity on t1 weighted images ; involving the left caudate , putamen , and internal globus pallidus . there was no restriction on diffusion - weighted images ( dwi ) and the apparent diffusion coefficient ( adc ) map was normal . for glycemic control , she was started on an insulin regimen ( bedtime insulin glargine and preprandial insulin aspart ) with sitagliptin . axial mri of the brain a ) axial t1-weighted mri of the brain showing right striatal increased signal intensity including right putamen , globus pallidus , and head of caudate . initially she was treated with lorazepam ( 2 - 6 mg / day ) to control her hh . while lorazepam improved the quality of her sleep , it had no effect on the chorea in her waking hours . valproic acid ( 400 mg / day ) had no clear effect on chorea and was discontinued due to intolerance . she was then given haloperidol ( gradually titrated from 1 mg / day to 8 mg / day ) and clonazepam ( titrated from 1.5 mg / day to 6 mg / day ) . she showed clinical improvement after a few days with improvement in her daily activities and gait . initially , there was more improvement in her lower extremities than upper extremities and the face over a period of 2 weeks . however , she achieved a satisfactory glycemic control , with a fasting serum glucose ranging from 6 to 7.8 mmol / l . with the initiation of neuroleptics and the glycemic control , three months later , she was in stable condition and had no recurrence of chorea . several studies2,3,5,6 investigated the triad of hemichorea or hemichorea / hemiballism , non - ketotic hyperglycemia , and striatal hyperintensity , and have suggested a new syndrome.3 patients suffering from hh share common clinicoradiologic features . in examining this saudi patient , we regarded this as a case of hh due to the unilateral choreoathetotic movement , hyperglycemia on presentation with poor glycemic control , and absent urine ketones , contralateral ti hyperintensity in the basal ganglia with no restriction on the adc map , and the absence of other metabolic derangements . the average age of onset ranges from 64 to 82 years.3 earlier case reports of hh suggested prevalence in females,4 but literature reviews indicate equal male to female incidence,3,5 which emphasizes the importance of accumulating case reports to better understand epidemiological characteristics . the patient in this study falls into the typical gender and age group for hh . abnormal movements usually involve one side of the body , but a few patients with bilateral movements were reported.6,7 some patients were newly diagnosed diabetics , and their hh was the first manifestation of the disorder.3,4 others , as in our patient , had longstanding diabetes.3,5,8,9 hyperglycemic hemichorea has a good prognosis and hemichorea rapidly ceases over a few days to weeks , after restoring glycemic levels with insulin only.3,5,8 there is enough evidence to speculate that radiological changes are also reversible . patients who had follow - up imaging studies showed resolution of changes on ct within 2 - 3 months and on mri within 6 - 11 months.3 however , a minority of cases had a different course . some patients did not improve on insulin alone , and required either short or long courses of additional pharmacologic therapies . ahlskog et al,4 and others reported cases with hyperglycemic dyskinesia that persisted as long as the patients were followed , 6 months up to 5 years , with patients showing no or slight improvement . these persisted despite the normalization of blood glucose and the use of pharmacologic agents.4,7 recurrence of symptoms after drug discontinuation was also reported in the literature.7 a few patients responded very poorly to all therapeutic measures and eventually died of secondary medical complications.6,10 several neuroleptic and anti - epileptic agents were cited in the literature to control hh . haloperidol ( 1 - 15 mg / day ) frequently showed good efficacy in managing hh,2 - 4,9 but dose escalation in refractory patients can be limited by side effects , such as tardive dyskinesia or hemiparkinsonism.7 moreover , risperidone ( 3 mg / day ) may be effective.4 the response to valproic acid was inconsistent . trials of lorazepam,10 chlorpromazine ( 12.5 mg / day ) , clonazepam ( 5 mg / day ) , reserpine ( 1.5 mg / day),8 and tetrabenazine ( 50 mg / day)2 lacked sufficient evidence of their effectiveness . trihexyphenidyl ( 6 mg / day ) , olanzapine , perphenazine , and biperiden were of no benefit.7,9 our experience supports the effectiveness of haloperidol , and the potential effectiveness of clonazepam while discouraging the use of lorazepam . in addition to the distinctive clinical features of hh , it has characteristic findings on brain imaging . brain mri gives a high - signal intensity on t1 images and normal- to low - signal intensity on t2 images.4 these observations align with the imaging findings in our patient . gradient echo images , dwi , and adc maps are usually normal,4,5 susceptibility weighted imaging ( swi ) is sensitive to blood products similar to blood oxygen level - dependent imaging . in cases of hypo perfusion of brain tissue , local vasodilation occurs in the ischemic tissues , which leads to increased extraction of oxygen and increased amount of deoxyhemoglobin in venous blood in that region . as deoxyhemoglobin is paramagnetic , it shows prominent hypointense signal on swi , and can be detected as hypointense venous vessels in the affected area.2 additional insights are gained by more sophisticated imagining modalities . magnetic resonance spectroscopy shows a decreased n - acetyl aspartate peak , which indicates a neuronal dysfunction or loss resulting from metabolic failure or hypoperfusion.6 positron emission tomography demonstrates reduced fluorodeoxyglucose ( fdg ) uptake in the corresponding basal ganglia , especially when performed later in the course of the illness,8 while showing increased fdg metabolism when performed earlier.9 similarly , single photon emission computed tomography ( spect ) studies show either increased8 or decreased cerebral perfusion of the affected stratum . this discrepancy , as noted by hsu et al,8 may be secondary to changes of cerebral vascular autoregulation or to the different stages of the pathological process at which the spect studies were carried out . several sound hypotheses have been proposed to explain the neuroimaging findings of such cases : mineralization , hyperosmolar insult , petechial hemorrhages , gliosis , transient ischemia , manganese accumulation , and gamma - amino butyric acid ( gaba ) transmission alteration . the reversibility of neuroimaging findings on follow - up studies rules out calcification as a possible cause . gamma - amino butyric acid deficiency in the basal ganglia as a result of its consumption as an energy substrate during hyperglycemia has been suggested.9 this fails to explain the unilaterality of symptoms and its persistence in some patients , as in this case study , beyond the hyperglycemic episode.7 several authors6,10 suggested that striatal petechial hemorrhage is the etiologic mechanism for hh and its t1 hyperintensity . only one histopathological autopsy report6 mentions hemosiderin deposits in a patient with hh , whereas another report10 describes microhemorrhages . these microhemorrhages supposedly result from hyperglycemia - induced blood brain barrier dysfunction . however , several observations are difficult to reconcile with this hypothesis : lesions frequently respected anatomic borders , t2 images are not hyperintense , and imaging evolution over time is not typical for bleeds.7 histopathological studies of cases with hh have heterogenous results , demonstrating infarcts , microhemorrhages , gliosis , and mineralization.10 nevertheless , they all have gemistocytic gliosis as a common findings . fujioka et al,5 experimentally reproduced similar striatal t1 hyperintensities and t2 hypointensities in rats by means of brief focal ischemia , which showed matching histological finding to cases of hh : selective neuronal death and astrocytosis rather than infarcts or bleeds . while the definite mechanism is still debated , it is fair to assume that a combination of the aforementioned processes is responsible for hh.7 due to microangiopathy , diabetics , especially poorly controlled diabetics , are predisposed to vascular ischemia , especially during a hyperglycemic crisis . a partial ischemic injury may cause selective neuronal death and gemistocytosis , interrupting striatal gabaergic transmission , disinhibiting the thalamus , and leading to abnormally excessive movement . in conclusion , diabetics are susceptible to hh , which is associated with t1 mri hyperintensity . clinicians should recognize this unique syndrome early as it is treatable with normalization of blood glucose . for patients who do not improve on insulin alone , we see a good therapeutic role for haloperidol , and a potential role for clonazepam . further research is needed to elucidate the underlying pathophysiology of hh .

hemichorea is a disorder characterized by abnormal , continuous , nonrhythmic , jerky , and distal movement involving one side of the body . it may result from cerebrovascular insult to basal ganglia , or from other causes including neoplasm , infection , and non - ketotic hyperglycemia . we report the clinical , laboratory , and neuroimaging data with treatment response of a saudi woman who has diabetes with left side hemichorea , involving the face , and upper and lower extremities , with unilateral right striatal hyperintense signal changes in t1 weighted mri , and a hyperglycemic state of longstanding uncontrolled diabetes . literature review suggested a syndrome with a triad of symptoms : non - ketotic hyperglycemia , hemichorea , and t1 mri striatal hyperintensities . as the number of internationally reported cases is still modest , reporting more patients will highlight aspects pertaining to the diagnosis and treatment of this condition . we present a patient who had a sustained therapeutic result from haloperidol and clonazepam .

SECTION 1. SHORT TITLE; AMENDMENT OF 1986 CODE. (a) Short Title.--This Act may be cited as the ``Economic Stimulus Tax Act of 1993''. (b) Amendment of 1986 Code.--Except as otherwise expressly provided, whenever in this Act an amendment or repeal is expressed in terms of an amendment to, or repeal of, a section or other provision, the reference shall be considered to be made to a section or other provision of the Internal Revenue Code of 1986. SEC. 2. REPEAL OF LIMITATION ON PASSIVE ACTIVITY LOSSES AND CREDITS. (a) In General.--Section 469 (relating to passive activity losses and credits limited) is hereby repealed. (b) Conforming Amendment.--The table of sections for subpart C of part II of subchapter E of chapter 1 is amended by striking the item relating to section 469. (c) Effective Date.--The amendments made by this section shall apply to taxable years beginning after December 31, 1993. SEC. 3. ACCELERATED DEPRECIATION SCHEDULE FOR REAL ESTATE. (a) In General.--Paragraph (1) of section 168(c) (relating to applicable recovery period) is amended by striking the items relating to residential rental property and nonresidential real property and inserting the following: ``Residential rental property................ 15 years Nonresidential real property................. 18 years''. (b) Effective Date.--The amendments made by this section shall apply to property placed in service after December 31, 1993. SEC. 4. RESTORATION OF 10-PERCENT INVESTMENT TAX CREDIT. (a) Allowance of Credit.--Section 46 (relating to amount of investment credit) is amended by striking ``and'' at the end of paragraph (2), by striking the period at the end of paragraph (3) and inserting ``, and'', and by adding at the end thereof the following new paragraph: ``(4) the general investment credit.'' (b) Amount of Credit.--Section 48 is amended by adding at the end thereof the following new subsection: ``(c) General Investment Credit.-- ``(1) In general.--For purposes of section 46, the general investment credit for any taxable year is an amount equal to 10 percent of the qualified investment for such taxable year. ``(2) Qualified investment.-- ``(A) In general.--For purposes of paragraph (1), the qualified investment for any taxable year is the aggregate of-- ``(i) the applicable percentage of the basis of each new section 38 property placed in service by the taxpayer during such taxable year, plus ``(ii) the applicable percentage of the cost of each used section 38 property placed in service by the taxpayer during such taxable year. ``(B) Applicable percentage.--For purposes of subparagraph (A), the applicable percentage for any property shall be determined under paragraphs (2) and (7) of section 46(c) (as in effect on the day before the date of the enactment of the Revenue Reconciliation Act of 1990). ``(C) Certain rules made applicable.--The provisions of subsections (b) and (c) of section 48 (as in effect on the day before the date of the enactment of the Revenue Reconciliation Act of 1990) shall apply for purposes of this paragraph. ``(3) Section 38 property.--For purposes of this subsection, the term `section 38 property' means-- ``(A) tangible personal property (other than an air conditioning or heating unit), or ``(B) other tangible property (not including a building and its structural components) but only if such property-- ``(i) is used as an integral part of manufacturing, production, or extraction or of furnishing transportation, communications, electrical energy, gas, water, or sewage disposal services, or ``(ii) constitutes a research facility used in connection with any of the activities referred to in clause (i), or ``(iii) constitutes a facility used in connection with any of the activities referred to in clause (i) for the bulk storage of fungible commodities (including commodities in a liquid or gaseous state), or ``(C) elevators and escalators, but only if-- ``(i) the construction, reconstruction, or erection of the elevator or escalator is completed by the taxpayer, or ``(ii) the original use of such elevator or escalator commences with the taxpayer, or ``(D) single purpose agricultural or horticultural structures; or ``(E) a storage facility (not including a building and its structural components) used in connection with the distribution of petroleum or any primary product of petroleum. Such term includes only property to which section 168 applies without regard to any useful life and any other property with respect to which depreciation (or amortization in lieu of depreciation) is allowable and having a useful life (determined as of the time such property is placed in service) of 3 years or more. ``(4) Coordination with other credits.--This subsection shall not apply to any property to which the energy credit or rehabilitation credit would apply unless the taxpayer elects to waive the application of such credits to such property. ``(5) Certain progress expenditure rules made applicable.-- Rules similar to rules of subsection (c)(4) and (d) of section 46 (as in effect on the day before the date of the enactment of the Revenue Reconciliation Act of 1990) shall apply for purposes of this subsection.'' (c) Technical Amendments.-- (1) Subparagraph (C) of section 49(a)(1) is amended by striking ``and'' at the end of clause (ii), by striking the period at the end of clause (iii) and inserting ``, and'', and by adding at the end thereof the following new clause: ``(iv) the basis of any new section 38 property and the cost of any used section 38 property.'' (2) Subparagraph (E) of section 50(a)(2) is amended by inserting ``or 48(c)(5)'' before the period at the end thereof. (3) Paragraph (5) of section 50(a) is amended by adding at the end thereof the following new subparagraph: ``(D) Special rules for certain property.--In the case of any section 38 property which is 3-year property (within the meaning of section 168(e))-- ``(i) the percentage set forth in clause (ii) of the table contained in paragraph (1)(B) shall be 66 percent, ``(ii) the percentage set forth in clause (iii) of such table shall be 33 percent, and ``(iii) clauses (iv) and (v) of such table shall not apply.'' (4)(A) The section heading for section 48 is amended to read as follows: ``SEC. 48. OTHER CREDITS.'' (B) The table of sections for subpart E of part IV of subchapter A of chapter 1 is amended by striking the item relating to section 48 and inserting the following: ``Sec. 48. Other credits.'' (d) Effective Date.--The amendments made by this section shall apply to periods after the date of the enactment of this Act under rules similar to the rules of section 48(m) of the Internal Revenue Code of 1986 (as in effect on the day before the date of the enactment of the Revenue Reconciliation Act of 1990). SEC. 5. 50 PERCENT DEDUCTION FOR CERTAIN CAPITAL GAINS. (a) Taxpayers Other Than Corporations.--Part I of subchapter P of chapter 1 (relating to treatment of capital gains) is amended by adding at the end the following new section: ``SEC. 1202. DEDUCTION FOR CERTAIN CAPITAL GAINS. ``(a) General Rule.--If for any taxable year a taxpayer other than a corporation has a qualified net capital gain, there shall be allowed as a deduction from gross income an amount equal to 50 percent of the qualified net capital gain. ``(b) Qualified Net Capital Gain.--For purposes of this section-- ``(1) In general.--The term `qualified net capital gain' means the lesser of-- ``(A) the net capital gain for the taxable year, or ``(B) the net capital gain for the taxable year determined by taking into account only gain or loss from qualified assets. ``(2) Qualified assets.--The term `qualified asset' means any property with a holding period of at least 1 year at the time of disposition, other than-- ``(A) stock or securities for which there is a market on an established securities market or otherwise, and ``(B) property (other than stock or securities) of a kind regularly traded on an established market. ``(c) Estates and Trusts.--In the case of an estate or trust, the deduction under subsection (a) shall be computed by excluding the portion (if any) of the gains for the taxable year from sales or exchanges of capital assets which, under section 652 and 662 (relating to inclusions of amounts in gross income of beneficiaries of trusts), is includible by the income beneficiaries as gain derived from the sale or exchange of capital assets.'' (b) Corporations.--Section 1201 (relating to alternative tax for corporations) is amended by redesignating subsection (b) as subsection (c) and by inserting after subsection (a) the following new subsection: ``(b) Deduction for Certain Capital Gains.-- ``(1) In general.--If for any taxable year a corporation has a qualified net capital gain, there shall be allowed as a deduction from gross income an amount equal to 50 percent of the qualified net capital gain. ``(2) Qualified net capital gain.--For purposes of this subsection, the term `qualified net capital gain' has the meaning given such term in section 1202(b).'' (c) Conforming Amendments.-- (1)(A) Subsection (h) of section 1 is amended by inserting after ``net capital gain'' each place it appears the following: ``(other than qualified net capital gain (within the meaning of section 1202(b))''. (B) Subsection (a) of section 1201 is amended by inserting after ``net capital gain'' each place it appears the following: ``(other than qualified net capital gain (within the meaning of section 1202(b))''. (2) Subsection (a) of section 62 is amended by adding at the end the following new paragraph: ``(15) Qualified net capital gains.--The deduction allowed by section 1202.'' (3)(A) The heading for section 1201 is amended to read as follows: ``SEC. 1201. ALTERNATIVE TAX FOR CORPORATIONS; DEDUCTION FOR CERTAIN CAPITAL GAINS.'' (B) The item relating to section 1201 in the table of sections for part I of subchapter P of chapter 1 is amended to read as follows: ``Sec. 1201. Alternative tax for corporations; deduction for certain capital gains.'' (4) The table of sections for part I of subchapter P of chapter 1 is amended by adding at the end the following new item: ``Sec. 1202. Deduction for certain capital gains.'' (d) Effective Date.--The amendments made by this section shall apply to sales and exchanges after the date of the enactment of this Act. SEC. 6. INCREASE IN DEDUCTIBLE HEALTH INSURANCE COSTS FOR SELF-EMPLOYED INDIVIDUALS. (a) Deduction Made Permanent.-- (1) In general.--Subsection (l) of section 162 (relating to special rules for health insurance costs of self-employed individuals) is amended by striking paragraph (6). (2) Conforming amendment.--Subsection (a) of section 110 of the Tax Extension Act of 1991 is amended by striking paragraph (2). (3) Effective date.--The amendments made by this subsection shall apply to taxable years beginning after December 31, 1991. (b) Deduction Increased to 100 Percent.-- (1) In general.--Paragraph (1) of section 162(l) is amended by striking ``25 percent'' and inserting ``100 percent''. (2) Effective date.--The amendment made by paragraph (1) shall apply to taxable years beginning after December 31, 1992. SEC. 7. RESTORATION OF INCOME AVERAGING. (a) In General.--Section 141 of the Tax Reform Act of 1986 (and the amendments made by such section) are hereby repealed, and the Internal Revenue Code of 1986 shall be applied and administered as if such section (and amendments) had not been enacted. (b) Effective Date.--The repeal made by this section shall apply to taxable years beginning after December 31, 1993. SEC. 8. MODIFICATIONS IN SOCIAL SECURITY TAXES. (a) Removal of Ceiling on Wages Subject to Tax.-- (1) FICA taxes.-- (A) Section 3121(a) (defining wages) is amended by striking paragraph (1). (B) Section 3121 is amended by striking subsection (x) (relating to applicable contribution base). (2) SECA tax.-- (A) Section 1402(b) (defining self-employment income) is amended-- (i) in the 1st sentence, by striking paragraph (1), and (ii) by striking the 2d sentence. (B) Section 1402 is amended by striking subsection (k) (relating to applicable contribution base). (b) Reduction in Social Security Taxes.-- (1) Employee tax.--Subsection (a) of section 3101 (relating to rate of tax on employees) is amended to read as follows: ``(a) Old-Age, Survivors, and Disability Insurance.--In addition to other taxes, there is hereby imposed on the income of every individual a tax equal to 4.55 percent of the wages (as defined in section 3121(a)) received by the individual with respect to employment (as defined in section 3121(b)).'' (2) Employer tax.--Subsection (a) of section 3111 (relating to rate of tax on employers) is amended to read as follows: ``(a) Old-Age, Survivors, and Disability Insurance.--In addition to other taxes, there is hereby imposed on every employer an excise tax equal to 4.55 percent of the wages (as defined in section 3121(a)) paid by the employer with respect to employment (as defined in section 3121(b)).'' (3) Self-employment tax.--Subsection (a) of section 1401 (relating to rate of tax on self-employment income) is amended to read as follows: ``(a) Old-Age, Survivors, and Disability Insurance.--In addition to other taxes, there is hereby imposed for each taxable year, on the self-employment income of every individual, a tax equal to 6.82 percent of the amount of the self-employment income for the taxable year.'' (c) Conforming Amendments.-- (1)(A) Paragraphs (2) and (3) of section 3121(i) (relating to computation of wages in certain cases) are each amended by striking ``, subject to the provisions of subsection (a)(1) of this section,''. (B) Paragraph (4) of section 3121(i) is amended by striking ``, subject to the provisions of subsection (a)(1),''. (C) Section 3121(s) (relating to concurrent employment by 2 or more employers) is amended by striking ``3102, 3111, and 3121(a)(1)'' and inserting ``3102 and 3111''. (2) Section 3122 (relating to Federal service) is amended by striking the 3d sentence. (3) Subsections (a), (b), (c), and (d) of section 3125 (relating to returns in the case of governmental employees in the States, Guam, American Samoa, and the District of Columbia) are each amended by striking the last sentence. (4)(A) Clause (i) of section 3231(e)(2)(A) is amended by striking ``The'' and inserting ``In the case of the taxes imposed by sections 3201(b), 3211(a)(2), and 3221(b), the''. (B) Subparagraph (B) of section 3231(e)(2) is amended to read as follows: ``(B) Applicable base.--For purposes of subparagraph (A), the term `applicable base' means for any calendar year the contribution and benefit base determined under section 230 of the Social Security Act for such calendar year; except that, for such purposes and for purposes of computing average monthly compensation under section 3(j) of the Railroad Retirement Act of 1974 (except with respect to annuity amounts determined under subsection (a) or (f)(3) of section 3 of such Act), clause (2) of the first sentence, and the second sentence, of section 230(c) of the Social Security Act shall be disregarded.'' (C) Subparagraph (C) of section 3231(e)(2) (defining compensation for purposes of railroad retirement tax) is amended by inserting after ``employers)'' the following: ``, as such section was in effect immediately before its repeal by the Farm and Small Business Tax Equity Act of 1993,''. (D) The heading of paragraph (2) of section 3231(e) is amended by striking ``bases'' and inserting ``base to tier 2 taxes''. (5) Section 6413 is amended by striking subsection (c) (relating to special refunds for employees receiving wages from more than 1 employer). (6) Section 230(c) of the Social Security Act (42 U.S.C. 430(c)) is amended by striking ``and sections 1402, 3121, 3122, 3125, 6413, and 6654 of the Internal Revenue Code of 1954''. (d) Effective Date.--The amendments made by this section shall apply with respect to remuneration paid after December 31, 1993, and with respect to earnings from self-employment attributable to taxable years beginning after such date. HR 912 IH----2

Economic Stimulus Tax Act of 1993 - Amends the Internal Revenue Code (IRC) to repeal the limitation on passive activity losses and credits. Shortens the recovery period (providing for accelerated depreciation) for residential rental property and nonresidental real property. Restores the ten-percent general investment tax credit. Allows individuals and corporations a deduction of 50 percent of the net capital gain from assets held for at least one year. Increases the deduction for health insurance costs for self-employed individuals from 25 percent to 100 percent. Makes such deduction permanent. Repeals the Tax Reform Act of 1986 to restore IRC provisions relating to income averaging. Removes the ceiling on wages subject to social security taxes and provides a reduction in such taxes.

Samantha Ray Mears has been charged with wielding a machete in order to force a man to have sex with her. Court documents allege that Mears entered the residence of an ex-boyfriend while he was not home. When the man returned home, Mears reportedly confronted him with a machete, ordered him to get on the bed, and remove his clothes. The man told police that he felt he could not leave the room without being hurt by Mears. Mears then removed her pants, climbed on top of the man, and engaged in intercourse, according to court documents. The man told police that Mears continued holding on to the machete during intercourse. The two began arguing, and the victim pretended to call an acquaintance but actually called 911, and was able to slowly back out of the room and escape. She also reportedly bit the victim on the arm, and officers noted a bite mark on his arm. The victim was able to provide officers with photos of Mears on the bed wielding the machete. Prosecutors requested that bond for Mears be set at $50,000. Mears, 19 years old, has been charged with two felonies: aggravated burglary, and assault with a weapon. She has also been charged with the following misdemeanors: unlawful restraint; partner/family member assault; and two counts of criminal mischief. There is no word yet on whether additional charges - such as sexual intercourse without consent - may be filed. ||||| One woman faces a slew of charges after her ex-boyfriend says she assaulted him while wielding a machete. On June 22, 2018, Great Falls police responded to a residence on 2nd Ave. NW for a report of a burglary. Charging documents state Samantha Mears entered the home of her ex-boyfriend, only identified as S.D., while she was armed with a machete. S.D was not home at the time of the break-in, but when he returned home to find Mears, she ordered him to get on the bed and remove his clothes. The victim says he complied out of fear. Then Mears and the victim engaged in intercourse during which she bit S.D. on the arm and continued having intercourse with him after he had tried to get her to stop. Afterward, Mears sat naked on the bed with the machete in hand which the victim provided multiple pictures of to investigators. An argument ensued when Mears is alleged to have ripped off a piece of trim from the wall and purposely peed on the bed. Eventually, the victim was able to escape and call for help. Mears claimed that she had been kidnapped by her ex-boyfriend and that he had given her a machete to protect herself. This is not the first time, however, that Mears has shown violence towards the victim. Two days prior to this incident, Mears was released on her own recognizance after being accused of Strangulation of a Partner or Family Member, the victim in that case also being S.D. She is now charged with Aggravated Burglary, Assault With a Weapon, Unlawful Restraint, Partner or Family Member Assault, and two counts of Criminal Mischief. The State has requested her bond be set in the amount of $50,000 and asks that Mears be required to stay 1500 feet away from the victim, his home, work, and vehicle. ||||| Samantha Mears, 19. (Photo: Courtesy) A Great Falls woman with a history of domestic violence against her ex-boyfriend was charged Friday after she allegedly armed herself with a machete and forced him to have sex with her. Samatha Ray Mears, 19, faces six new charges, including aggravated burglary, assault with a weapon, unlawful restraint, partner family member assault and two counts of criminal mischief. In April, she was charged with felony strangulation for allegedly assaulting the same victim. DOMESTIC ABUSE: Killed by the one you love: Montana domestic homicides increasing The alleged victim in the case told police he had come home Friday night and Mears, who entered the home when no one was there, appeared from behind his bedroom door wielding a machete. According to the June, 23 police report completed the next day, the man said she held the machete to this neck and ordered him to remove his clothes. After they had sex, the man reportedly tried to push Mears off of him, but she bit him on the arm, and continued trying to have sex with him. They began to argue, the man said, and Mears ripped a large piece of trim off the wall and urinated on the bed. HELP FOR VICTIMS: Resources available to victims of domestic violence At some point, the man heard his sister enter the home and he texted her to leave the house. Around 11 p.m., he called 9-1-1 but pretended to talk to "Doug," so Mears wouldn't know he was calling for help, police reported. The alleged victim and his sister reportedly fled the home, just as police arrived. Great Falls police noted Mears seemed to be suffering from some sort of mental illness. She said the man had kidnapped her and gave her a machete to protect herself, according to police. In April, Mears was charged with felony strangulation of a partner after another argument escalated at the victim's home. In that case, according to court documents, Mears had grabbed his hair and hit him in the face. The man was able to get the Mears off him, "but was hesitant about physically protecting himself, as he thought he would get into legal trouble if he did." The argument, however, continued, and the man told police Mears began strangling him by pressing her thumbs on his windpipe. Court documents indicate the pair had been in a relationship for approximately seven years. Read or Share this story: https://gftrib.com/2N09JUE

– A 19-year-old Montana woman was arrested Friday after allegedly lying in wait for her ex-boyfriend with a machete and forcing him to have sex with her. The alleged victim, who had reportedly been in a relationship with Samantha Ray Mears for seven years before they broke up, told police he came home Friday night and Mears came out from behind his bedroom door holding a machete, which she then placed to his neck as she ordered him to take off his clothes, the Great Falls Tribune reports. She allegedly took off her own pants and forced him to have intercourse with her, continuing to hold on to the machete the whole time, KRTV reports. When he tried to push her off him, she allegedly bit his arm and continued attempting to have sex despite him telling her to stop, KFBB reports. They then started arguing, the man says, and Mears allegedly pulled some trim off the wall and peed on the bed. The alleged victim was able to take pictures of Mears sitting naked on the bed wielding the machete, which he provided to police. Finally, he was able to call 911 and pretend to be talking to a friend so Mears wouldn't know he'd called police; he and his sister, who had arrived home during the ordeal, escaped the house just as police got there. Mears, who was also charged with felony strangulation against the same man in April, now faces six new charges, including assault, burglary, and more.

although very uncommon , these potential complications should be considered when a patient presents with abdominal pain following colonoscopy . splenic rupture following colonoscopy has been reported 17 times ( 18 including our case ) in the english - language literature , with the first reported case in 1974 . symptoms were usually reported within the first 24 hours after colonoscopy , and nearly all cases resulted in splenectomy . the proposed mechanism for injury to the spleen involves avulsion of the splenic capsule from excess traction on the splenocolic ligament during colonoscopy . this traction is from movement of the scope itself and excess torque against the wall of the colon , placing traction on these ligaments . excess traction resulting in splenic rupture can occur during routine colonoscopy or as more commonly reported during colonoscopy with polypectomy . one other mechanism that has been proposed is excess traction on the ligaments generated by external pressure on the left hypochondrium used to straighten the scope during colonoscopy . splenic rupture may go unrecognized or the diagnosis may be delayed because of its rare occurrence and presentation of pain that may often be attributed to the instillation of air during the colonoscopy itself . appendicitis after colonoscopy has been reported 10 times in the literature , to our knowledge , including our case . it has been suggested that excess pressure from the endoscope at the appendiceal lumen and possible excess inflation can result in inflammation secondary to trauma or can lead to formation of a fecalith . it has also been reported that impaction of stool at the appendix orifice during colonoscopy can lead to obstructive appendicitis . a 76-year - old woman underwent colonoscopy with biopsy of a 1-mm cecal polyp and biopsy of a 1.5-cm ileal nodule 10 cm from the ilealcecal valve . her medical history is significant for endometrial cancer treated with total abdominal hysterectomy and bilateral oophorectomy ( tah - bso ) , a large hiatal hernia , and cecal tubular adenoma removed endoscopically . thirty minutes after this colonoscopy , she was found to be hypotensive , with a systolic blood pressure of 71 over a diastolic pressure of 51 , diaphoretic , pale , and nervous . she was admitted to the intensive care unit with a hemoglobin level of 8.4g / dl and a hematocrit of 25% , placed on norepinephrine to support her blood pressure , and transfused with packed red blood cells . the surgical service was asked to consult the following day , after she remained hypotensive , required multiple blood transfusions , and had a computed tomographic ( ct ) scan that showed massive hemoperitoneum ( figure 1 ) . at this time , she was taken for emergency laparotomy , during which she was found to have splenic rupture with avulsion of the splenic capsule and splenocolic ligaments . the spleen was a normal size , measuring 54 g with no pathology found on gross or microscopic examination . postoperatively , she did well and was transferred from the intensive care unit to a regular surgical floor on postoperative day 2 . a 60-year - old male presented to the emergency department 16 hours after a screening colonoscopy , during which he underwent sigmoid polypectomy of a 5-mm , tubular adenoma . upon presentation to the emergency department , he was complaining of 8 hours of worsening right lower quadrant ( rlq ) pain , nausea , and vomiting . his past medical history is significant for hypertension , coronary artery disease , myocardial infarction , and hyperlipidemia . on admission , computed tomography scan demonstrated a retrocecal appendix with a small appendicolith , wall thickening , and periappendiceal inflammation . the patient was admitted to the hospital and underwent laparoscopic appendectomy for a grossly inflamed appendix with fecalith . colonoscopy is a fairly safe procedure , with bleeding and perforation reported as the most common complications . other , rare , complications include hepatic portal vein gas , pneumomediastinum , pneumothorax , and diverticulitis , among others . the rare complications of colonoscopy we have reported , cases of splenic rupture and appendicitis , occur with infrequency . computed tomography can be useful when the diagnosis is not clear in a patient who has recently undergone a colonoscopy and presents with significant physical findings . not previously reported is one factor unique to our case of splenic rupture , entry into the ileum with ileal biopsy . this could theoretically contribute to increased torque of the scope at the splenic flexure secondary to the increased working distance of the scope . these rare complications that we have reported often present with nonspecific signs of abdominal pain , and clinicians must have a high index of suspicion and awareness of these entities to make their diagnosis .

background : appendicitis and splenic rupture are 2 rare complications of colonoscopy reported in the literature . to our knowledge splenic rupture following colonoscopy has been reported 17 times in the english - language literature and is associated with excess traction on the splenocolic ligament . appendicitis after colonoscopy has been reported only 9 times and is usually associated with obstruction of the appendiceal lumen with fecal matter during colonoscopy . methods : we present the case reports of 2 patients : a 76-year - old woman who presented in consultation 24 hours after a routine colonoscopy with massive hemoperitoneum secondary to splenic rupture , seen on computed tomographic ( ct ) scan , who then underwent splenectomy ; the second , a 60-year - old male who presented to the emergency room 16 hours after colonoscopy with clinical and computed tomographic scan findings of acute appendicitis who underwent a laparoscopic appendectomy . results : treatment of both patients resulted in resolution of their complications , splenic rupture and appendicitis . they both had an uneventful postoperative course and are doing well several months postoperatively . conclusions : we report 2 rare complications of colonoscopy , splenic rupture and appendicitis . in the setting of a recent colonoscopy and abdominal pain , a high index of suspicion is needed for their diagnosis .

SECTION 1. SHORT TITLE. This Act may be cited as the ``Lumbee Recognition Act''. SEC. 2. PREAMBLE. The preamble to the Act of June 7, 1956 (70 Stat. 254), is amended-- (1) by striking out ``and'' at the end of each of the first three clauses; (2) by striking out ``: Now therefore,'' at the end of the last clause and inserting in lieu thereof a semicolon; and (3) by adding at the end thereof the following new clauses: ``Whereas the Lumbee Indians of Robeson and adjoining counties in North Carolina are descendants of coastal North Carolina Indian tribes, principally Cheraw, and have remained a distinct Indian community since the time of contact with white settlers; ``Whereas the Lumbee Indians have been recognized by the State of North Carolina as an Indian tribe since 1885; ``Whereas the Lumbee Indians have sought Federal recognition as an Indian tribe since 1888; and ``Whereas the Lumbee Indians are entitled to Federal recognition of their status as an Indian tribe and the benefits, privileges, and immunities that accompany such status: Now, therefore,''. SEC. 3. FEDERAL RECOGNITION. The Act of June 7, 1956 (70 Stat. 254), is amended-- (1) by striking out the last sentence of the first section; and (2) by striking out section 2 and inserting in lieu thereof the following: ``federal recognition; acknowledgment ``Sec. 2. (a) Federal recognition is hereby extended to the Lumbee Tribe of Cheraw Indians of North Carolina. All laws and regulations of the United States of general application to Indians and Indian tribes shall apply to the Lumbee Tribe of Cheraw Indians of North Carolina and its members. ``(b) Notwithstanding the first section of this Act, any group of Indians in Robeson or adjoining counties whose members are not enrolled in the Lumbee Tribe of Cheraw Indians of North Carolina, as determined under section 4(b), may petition under part 83 of title 25 of the Code of Federal Regulations for acknowledgment of tribal existence. ``services ``Sec. 3. (a) The Lumbee Tribe of Cheraw Indians of North Carolina and its members shall be eligible for all services and benefits provided to Indians because of their status as federally recognized Indians, except that members of the tribe shall not be entitled to such services until the appropriation of funds for these purposes. For the purposes of the delivery of such services, those members of the tribe residing in Robeson and adjoining counties, North Carolina, shall be deemed to be resident on or near an Indian reservation. ``(b) Upon verification of a tribal roll under section 4 by the Secretary of the Interior, the Secretary of the Interior and the Secretary of Health and Human Services shall develop, in consultation with the Lumbee Tribe of Cheraw Indians of North Carolina, a determination of needs and a budget required to provide services to which the members of the tribe are eligible. The Secretary of the Interior and the Secretary of Health and Human Services shall each submit a written statement of such needs and budget with the first budget request submitted to the Congress after the fiscal year in which the tribal roll is verified. ``(c)(1) The Lumbee Tribe of Cheraw Indians of North Carolina is authorized to plan, conduct, consolidate, and administer programs, services, and functions authorized under the Act of April 16, 1934 (48 Stat. 596; 25 U.S.C. 452, et seq.), and the Act of November 2, 1921 (42 Stat. 208; 25 U.S.C. 13), popularly known as the Snyder Act, pursuant to an annual written funding agreement among the Lumbee Tribe of Cheraw Indians of North Carolina, the Secretary of the Interior, and the Secretary of Health and Human Services, which shall specify-- ``(A) the services to be provided, the functions to be performed, and the procedures to be used to reallocate funds or modify budget allocations, within any fiscal year; and ``(B) the responsibility of the Secretary of the Interior for, and the procedure to be used in, auditing the expenditures of the tribe. ``(2) The authority provided under this subsection shall be in lieu of the authority provided under the Indian Self-Determination and Education Assistance Act (25 U.S.C. 450, et seq.). ``(3) Nothing in this subsection shall be construed as affecting, modifying, diminishing, or otherwise impairing the sovereign immunity from lawsuit enjoyed by the Lumbee Tribe of Cheraw Indians of North Carolina or authorizing or requiring the termination of any trust responsibility of the United States with respect to the tribe. ``constitution and membership ``Sec. 4. (a) The Lumbee Tribe of Cheraw Indians of North Carolina shall organize for its common welfare and adopt a constitution and bylaws. Any constitution, bylaws, or amendments to the constitution or bylaws that are adopted by the tribe must be consistent with the terms of this Act and shall take effect only after such documents are filed with the Secretary of the Interior. The Secretary shall assist the tribe in the drafting of a constitution and bylaws, the conduct of an election with respect to such constitution, and the reorganization of the government of the tribe under any such constitution and bylaws. ``(b)(1) Until the Lumbee Tribe of Cheraw Indians of North Carolina adopts a constitution and except as provided in paragraph (2), the membership of the tribe shall, subject to review by the Secretary, consist of every individual who is named in the tribal membership roll that is in effect on the date of enactment of this Act. ``(2)(A) Before adopting a constitution, the roll of the tribe shall be open for a 180-day period to allow the enrollment of any individual previously enrolled in another Indian group or tribe in Robeson or adjoining counties, North Carolina, who demonstrates that-- ``(i) the individual is eligible for enrollment in the Lumbee Tribe of Cheraw Indians; and ``(ii) the individual has abandoned membership in any other Indian group or tribe. ``(B) The Lumbee Tribe of Cheraw Indians of North Carolina shall advertise in newspapers of general distribution in Robeson and adjoining counties, North Carolina, the opening of the tribal roll for the purposes of subparagraph (A). The advertisement shall specify the enrollment criteria and the deadline for enrollment. ``(3) The review of the tribal roll of the Lumbee Tribe of Cheraw Indians of North Carolina shall be limited to verification of compliance with the membership criteria of the tribe as stated in the Lumbee Petition for Federal Acknowledgment filed with the Secretary by the tribe on December 17, 1987. The Secretary shall complete his review and verification of the tribal roll within the 12-month period beginning on the date on which the tribal roll is closed under paragraph (2). ``jurisdiction ``Sec. 5. (a)(1) The State of North Carolina shall exercise jurisdiction over-- ``(A) all criminal offenses that are committed on, and ``(B) all civil actions that arise on, lands located within the State of North Carolina that are owned by, or held in trust by the United States for, the Lumbee Tribe of Cheraw Indians of North Carolina, any member of the Lumbee Tribe of Cheraw Indians of North Carolina, or any dependent Indian community of the Lumbee Tribe of Cheraw Indians of North Carolina. ``(2) The Secretary of the Interior is authorized to accept on behalf of the United States, after consulting with the Attorney General of the United States, any transfer by the State of North Carolina to the United States of any portion of the jurisdiction of the State of North Carolina described in paragraph (1) pursuant to an agreement between the Lumbee Tribe of Cheraw Indians and the State of North Carolina. Such transfer of jurisdiction may not take effect until two years after the effective date of such agreement. ``(3) The provisions of this subsection shall not affect the application of section 109 of the Indian Child Welfare Act of 1978 (25 U.S.C. 1919). ``(b) Section 5 of the Act of June 18, 1934 (Chapter 576; 25 U.S.C. 465), and the Act of April 11, 1970 (84 Stat. 120; 25 U.S.C. 488 et seq.), shall apply to the Lumbee Tribe of Cheraw Indians of North Carolina with respect to lands within the exterior boundaries of Robeson and adjoining counties, North Carolina. ``authorization of appropriations ``Sec. 6. (a) There are authorized to be appropriated such funds as may be necessary to carry out this Act. ``(b) In the first fiscal year in which funds are appropriated under this Act, the tribe's proposals for expenditures of such funds shall be submitted to the Select Committee on Indian Affairs of the Senate and the Committee on Natural Resources of the House of Representatives 60 calendar days prior to any expenditure of such funds by the tribe.''. Passed the House of Representatives October 28, 1993. Attest: DONNALD K. ANDERSON, Clerk.

Lumbee Recognition Act - Extends Federal recognition to the Lumbee Tribe of Cheraw Indians of North Carolina.

ithe major galaxy mergers in galaxy formation inevitably leads to the presence of a binary black hole ( bbh ) located in the center of a giant galaxy @xcite . the following observational results provide possible evidence of the presence of bbhs : double compact cores @xcite , two broad - line emission systems @xcite , the x - shaped morphology of radio lobes @xcite , wiggle patterns of radio jets @xcite , periodic variations and periodic outbursts @xcite , and the orbital motion of the compact core @xcite . strong evidence for bbhs as linking some observational results , however , has not yet been found . clarifying the mechanism for the formation of bbhs is essential in the study of galaxy mergers in galaxy formation @xcite , in the role of black hole mergers in the evolution of supermassive black holes @xcite , and in the detection of gravitational waves at the phase of bbh orbital decay @xcite . is a nearby low - luminosity fr i radio galaxy and giant elliptical galaxy with a redshift ( @xmath8 ) of 0.0213 @xcite , and has the strong jet and counter jet that extend to about 100 kiloparsecs ( kpc ) which have been observed at radio @xcite , infrared @xcite , optical @xcite and x - ray waves @xcite . the orbital motion of the compact core in , which has a period of @xmath1 years , was observed with a position accuracy of 10 micro arcseconds ( @xmath9as ) by using phase - referencing very long baseline interferometry ( vlbi ) @xcite . several observational and theoretical studies have shown that the periodic flux variation and periodic outburst activities in the radio , optical , x - ray , and @xmath10-ray light curves are associated with the orbital motion of a bbh in the center of the galaxies @xcite . here we report the detection of a signal periodicity in light curves from the compact core of , which indicates the presence of a very close bbh in the center of this object , and also present evidence for black hole mergers . we use a hubble constant ( @xmath11 ) of 71 km s@xmath12 mpc@xmath12 , the matter density ( @xmath13 ) of 0.27 and the vacuum energy ( @xmath14 ) of 0.73 in this letter , resulting that an angular size or separation of 1 milliarcsecond ( mas ) corresponds to 0.436 pc at the distance of 3c 66b . the millimeter - wavelength flux variation for was monitored every two weeks from the end of 2003 through to the beginning of 2005 at 93.716 ghz using the nobeyama millimeter array ( nma ) of the national astronomical observatory of japan ( naoj ) , and every four weeks from the end of 2005 through to the middle of 2006 at 86.2 ghz using the plateau de bure interferometer ( pdbi ) of the institut de radioastronomie millimtrique ( iram ) . these flux monitor observations using two - type millimeter arrays will enable us to eliminate any dependence on the characteristic features of each array , giving us more reliable and accurate results . in the nma observation , and were observed as a visibility calibrator . also , the flux densities of each calibrator were precisely derived by observing and . phase fluctuations in the observation are caused by short - term variations of the excess path length in the atmosphere , which is mainly due to the time variation of water vapor pressure . since these phase variations cause decoherence in the visibility data , it is necessary to correct this loss . the decoherence factors at all observation epochs were estimated from the synthesized maps of each visibility calibrator @xcite . to accurately derive the flux densities of the observed object , the flux data at epochs with a decoherence of more than 20 % were flagged . and were observed for the bandpass calibration . the weighted mean of the flux density data that were estimated from each visibility calibrator was plotted . in the pdbi observation , the flux densities of were corrected by observing and the compact h@xmath15 region , and/or , except on january 14 and on july 23 in 2006 . the phase and bandpass calibrations were performed by itself . we first investigated the contribution of large - scale jet emissions into observed flux densities . a map of with millimeter jets can be made by combining the visibility data obtained from the nma monitoring observations for all epochs ( see figure 1a ) . the total flux density of the millimeter map of 3c 66b at 93 ghz exceeds 500 mjy , while the sum of the expanding jet and counter jet is less than 24 mjy . we made the spectral energy distributions ( seds ) of the jet and the counter jet from our data and other data at different wavelengths , respectively . we found that these seds follow ( agree with ) a simple power - law synchrotron model , even though the flux densities at all wavelengths were observed at the different dates ( see figure 1b ) . this fact indicates that the observed flux variations of were dominated by the unresolved core , not by the expanding jet and counter jet . figure 2 shows the 3-mm peak flux monitor data obtained from the unresolved core of between 2003 november and 2006 august , and the spectral analysis results from these monitor data by using lomb - scargle periodogram @xcite . from these results , we detected a periodic flux variation on a cycle of 93@xmath161 days with a maximum - to - minimum amplitude ratio of @xmath17 , and non - periodic flux variation from the unresolved core . the variability timescale of the observed signal is shorter than that of the orbital period of about 1 year . due to the orbital motion around the center of gravity in a bbh , the doppler factor for the emitting region is a periodical function of time @xcite , and the observed signal periodicity has a geometrical origin due to doppler - shifted modulation . compared to the intrinsic period , the observed signal period is shortened by the relativistic effect @xcite . it is also noted that the non - periodic flux variation may be caused by the non - thermal radiation in the flaring state that is emitted by a relativistic emission region not directly affected by a bbh ( e.g. , a shock in the knots of jet in the core that is not resolved with the angular resolutions of nma and pdbi ) . both the observed flux variation ( see figure 2 ) and the orbital motion @xcite were well fitted by a simple model of sin function . this result indicates that the difference between the apogee and perigee velocities will be small , and that the doppler boosting factor will be small . if they were large , the profile of the observed flux variation would be that of a spike like the periodic outburst activities in the flaring state . this indicates that the binary system in has a nearly circular orbit . as a consequence of the binary orbital revolution around the center of gravity , the observed signal period ( @xmath18 ) is related to the orbital period ( @xmath19 ) by @xcite @xmath20 where @xmath21 is @xmath22 with the jet outflow velocity of @xmath23 and the light speed of @xmath24 , and @xmath25 is the inclination angle between the jet axis and the line of sight . the apparent speed in the relativistic jet is written by @xcite @xmath26 given the detected signal period ( @xmath18 ) of 93@xmath161 days , the orbital period ( @xmath19 ) of @xmath1 years @xcite , and the derived apparent speed ( @xmath27 ) of [email protected] ( see figure 3 ) , the following physical parameters for an inner - jet outflow that has the effect of the bbh orbital motion found in were estimated from equations ( [ eq : period ] ) and ( [ eq : apparent ] ) ; a speed ( @xmath21=@xmath22 ) of [email protected] and an inclination angle ( @xmath25 ) of [email protected] degrees in accordance with the standard model for jet bulk motion . consequently , the derived doppler factor ( @xmath28 ) of 2.8 [ = @xmath29 is a small value that does not have a strong effect on the profile of the periodical flux variation . the jet is presumably linked to the accretion disk around a black hole . at least one of the two black holes in a binary system will have an accretion disk . if both of the black holes have an accretion disk , the relationship between the observed jet and the two black holes is not simple . assuming that the observed jet is dominated by the accretion disk around either one of the two black holes , we show two schematic geometries of a bbh in figure 4 . the orbital motion velocity ( @xmath30 ) around the center of gravity can be written as @xmath31 , where @xmath32 is the intrinsic orbital frequency . the observed flux modulation by doppler boosting can be written by @xmath33 where @xmath34 is the intrinsic spectral flux density in the comoving frame , @xmath35 is the source spectral index ( @xmath36 ) , and @xmath37 is the doppler factor including the time variation due to the orbital motion of the bbh , which is written by @xcite @xmath38 where @xmath39 is @xmath40 . from equation ( [ eq : flux ] ) , the observed maximum - to - minimum flux ratio can be expressed as @xmath41 by applying this model to the sin curve of the periodic flux variation caused by a bbh ( see figure 2 ) , an orbital motion velocity ( @xmath30 ) of the bbh can be derived from equations ( [ eq : doppler ] ) and ( [ eq : ratio ] ) , and an orbital radius ( @xmath42 ) of @xmath43 cm [ @xmath44 pc ] can then be estimated when @xmath35=0 . although an upper limit for the orbital radius could only be estimated from the core motion using phase - referencing vlbi @xcite , the orbital radius of a bbh can be directly derived by adding the periodic flux monitor data that we found successfully . from two types of geometry of a bbh system shown in figure 4 , an orbital separation ( @xmath45 ) of two black holes is @xmath46 ( see figure 4a ) or @xmath47 ( see figure 4b ) when @xmath48 , where @xmath49 and @xmath50 denote the mass of the smaller and larger black holes , respectively . since the revolution period of a two - body problem with a circular orbit has a relational expression of @xmath51 ( where @xmath52 is the gravitational constant ) , the mass of the larger black hole ( @xmath50 ) is estimated to be @xmath53 or @xmath54 @xcite demonstrated a tight correlation between the black hole masses and the velocity dispersions of their host bulges , and @xcite then derived the relationship between central stellar velocity dispersions and black hole masses . based on this relationship , an estimated mass of @xmath55 @xmath5 @xcite is adopted as the total mass of the two black holes [ @xmath56 for 3c 66b , where @xmath5 is the mass of the sun . from equations ( [ eq : small ] ) and ( [ eq : large ] ) , the following basic bbh physical parameters were estimated ; the larger black hole mass of @xmath4 @xmath5 , the smaller black hole mass of @xmath6 @xmath5 , and the separation ( @xmath45 ) between the black holes of @xmath57 cm [ @xmath3 pc ] that corresponds to about @xmath58 times the schwarzschild radius ( @xmath59 ) of @xmath60 cm [ @xmath61 pc , @xmath62 au ] . this estimated separation is much shorter than that of a celestial object recently identified as being a potential sub - parsec bbhs by @xcite , revealing the presence of a very close bbh in the center of . the decay time of a bbh in the center of due to the gravitational radiation is estimated to be @xmath7 years using the following equation @xcite @xmath63 the estimated decay time is much shorter than the hubble time . the model of galaxy formation based on @xmath64cdm indicates that there were a large number of galaxy mergers , which led to giant elliptical galaxies . centaurus a ( cena ) , which is the nearby radio galaxy and bright elliptical galaxy , has the prominent warped dust lane and gas disk in the central region ( e.g. , @xcite ) , suggesting that cen a experienced a recent merging event during a few @xmath65 years ( @xcite and references therein ) . 3c66b is a giant elliptical galaxy within the cluster abell 347 @xcite and has the prominent face - on dust lane @xcite . these indicate that 3c 66b differs from quasars with active merging @xcite and is one of nearby radio galaxies that experienced the galaxy merging event . within a timescale of @xmath65 years , two black holes caused after the galaxy merging event would come closer to each other due to the dynamical friction and gas interaction , and then merge into one due to the gravitational - wave radiation ( e.g. , @xcite ) . in conclusion , this shows a possibility that a very close bbh in the center of exists just before its merger into one black hole . the detection of strong gravitational - wave radiation is expected during the final stage of a black hole merger . in this letter , the following assumptions are adopted ; 1 ) the derived apparent speed of the jet is equal to the bulk flow speed ; 2 ) the jet axis is parallel to the binary angular momentum and is perpendicular to the accretion disk around a black hole by which the observed jet is formed ; 3 ) the bbh has a binary orbit with an orbital eccentricity of zero ( this is a circular orbit ) ; and 4 ) the spectral index is zero at around our observing frequencies . it is theoretically suggested that the pattern speed is slower than the bulk flow speed of the jet @xcite , while the study on the relativistic bulk motion in about 100 agns demonstrates that there is no clear distinction between these speeds @xcite . for instance , the ratio of these speeds for grs1919 + 105 was estimated to be 0.8 @xcite . as our estimated proper motion has an error of 15 % that is comparable to this uncertainty , the assumption 1 ) can be considered reliable in this letter . the complexity of mergers and active galactic nuclei ( agns ) feeding may not support the assumptions 2 ) and 3 ) . to evaluate these assumptions , it is necessary to monitor the flux variation with higher precision as closely as possible . if these assumptions are not entirely inappropriate , however , our derived physical parameters are not significantly changed . since the synchrotron radiation from the agn core is expected to be optically thin or peak at around our observing frequencies , we adopted the assumption 4 ) in this letter . when @xmath66 as compared with @xmath67 , the derived physical parameters of a bbh in are changed at a factor of 1 to 3 . using the atacama large millimeter / submillimeter array ( alma ) including the atacama compact array ( aca ) that is used to obtain precise images of celestial objects with high angular resolution @xcite , the multi - wavelength profile of the periodic flux variation and periodic outburst activities of candidate objects can be monitored with precision of one mjy or better . the spike profile of the periodic flux variation will provide us with the orbital eccentricity of a bbh in and the relationship between the jet axis and the binary angular momentum . in addition , the multi - wavelength profile will improve our derived basic physical parameters of the bbh with high precision ; the orbital radius , the orbital separation and the masses of the two black holes , and the decay time . we thank m. saito for his useful comments , t. hasegawa for his comments on data analysis , h. suda for his support with regard to the nma observations and data reduction , and r. neri for the technical help he provided for the pdbi data reduction . this research was partially supported by the ministry of education , culture , sports , science and technology ( mext ) of japan , grant - in - aid for young scientists ( b ) 17740114 , 2005 - 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recent observational results provide possible evidence that binary black holes ( bbhs ) exist in the center of giant galaxies and may merge to form a supermassive black hole in the process of their evolution . we first detected a periodic flux variation on a cycle of @xmath0 days from the 3-mm monitor observations of a giant elliptical galaxy for which an orbital motion with a period of @xmath1 years had been already observed . the detected signal period being shorter than the orbital period can be explained by taking into consideration the doppler - shifted modulation due to the orbital motion of a bbh . assuming that the bbh has a circular orbit and that the jet axis is parallel to the binary angular momentum , our observational results demonstrate the presence of a very close bbh that has the binary orbit with an orbital period of @xmath1 years , an orbital radius of @xmath2 pc , an orbital separation of @xmath3 pc , the larger black hole mass of @xmath4 @xmath5 , and the smaller black hole mass of @xmath6 @xmath5 . the bbh decay time of @xmath7 years provides evidence for the occurrence of black hole mergers . this letter will demonstrate the interesting possibility of black hole collisions to form a supermassive black hole in the process of evolution , one of the most spectacular natural phenomena in the universe .

with the rapid change in the demographic profile of india , the prevalence of chronic diseases of the elderly like dementia and dm type 2 is increasing . in india , over 3.7 million people aged 60 years and above suffer from dementia , predominantly of alzheimer 's type . assuming that the current prevalence rate remains stable , these numbers are projected to increase to 6.35 million by 2025 . studies from india indicate that apoe4 allele is significantly associated with ad , and it is a risk factor [ 25 ] . there has been a pandemic rise of dm especially among asian indians . currently 40.9 million indians suffer from dm , and this is projected to increase to 69.9 million by 2025 . genetic predisposition and environmental factors dm type 2 which accounts for 90% of dm is predominantly a polygenic disease with various loci identified at pgc-1 , pc-1 ( k121q ) , irs-2 , mody , and so forth . many population - based cross - sectional studies and prospective studies [ 913 ] have indicated that dm or abnormal glucose tolerance doubled the risk of ad ( rr 1.372.27 ) ; though others have not confirmed this link . tripathi et al . , in a study from northern india , reported dm as a risk factor for dementia ; 33.3% of their sample with dementia had diabetes compared to 9% of the controls ( p < 0.001 ) . in a large population - based study of japanese american men found a significant association between dm , ad , and apoe4 carriers ; subjects with apoe4 allele and dm had a relative risk of 5.5 for ad . matsuzaki et al . in a retrospective analysis of autopsies found a very significant positive association between hyperglycaemia , ad neuropathology , and apoe4 status ( or 38.9 ) . we conducted a hospital - based cross - sectional study of dementia , to evaluate the interaction between ad and diabetes , as a function of the apoe4 allele status . consecutive persons with dementia attending the geriatric clinic of the department of psychiatry in national institute of mental health and neurosciences ( nimhans ) , bangalore , and their consenting offspring were invited to participate in this study . this sample is part of a larger study of genetic and clinical correlates in dementia , and details about evaluation have been reported earlier . in this paper , the study sample ( n = 594 ) included ad ( n = 209 ) , nad ( n = 122 ) , f / had ( n = 70 ) , and nc ( n = 193 ) . the nad group consisted of vascular and mixed dementia ( n = 46 ) , frontotemporal dementia ( n = 30 ) , lewy body dementia ( n = 10 ) , and other dementias ( n = 36 ) . the study was approved by the ethics committee of nimhans , and informed consent was collected prior to participation . all the subjects were evaluated using a standard protocol including general clinical evaluation , functional assessment ( everyday abilities scale for india , easi ) , neuropsychology testing ( hindi mental status examination , hmse ) , laboratory investigations ( haemogram , blood glucose levels ) , and genotyping and imaging ( mri scans using a 1.5 or 3 tesla machine ; or ct scan ) whenever possible . clinical evaluation was done by trained psychiatric residents and the diagnosis of dementia established using icd-10 criteria . their co - morbid dm was recorded based on laboratory results or self - reports , being on antidiabetic medication . ten millilitres of venous blood was collected , and dna was extracted using salting out method . polymerase chain reaction ( pcr ) the results were corroborated with real - time pcr results for 10% of the samples in every experiment . we compared apoe4 frequency and dm status in ad , nad , f / had , and nc . comparisons between variables were done using chi - square test for categorical variables and unpaired t - test for continuous variables . fisher 's exact test was used when any of the values in the contingency table was less than 10 . odds ratios and p values were computed , and statistical significance was inferred if p < 0.05 . based on the sample selection , ad , nad , and the nc were older than 60 years ( 61.14 11.40 years ; 61.73 12.41 years ; 60.35 15.65 years , resp . ) . the ad , nad , and nc group had crossed the age at risk for onset of dm . results show that on average , 11.6% of our study group had developed dm . however , the prevalence of dm differed between the various groups , being17.7% of the ad , 13.9% of the nad , 6.2% of the nc , and 4.3% of the f / had ( table 1 ) . apoe4 carrier rates in ad ( n = 98/209 ) were higher than age - matched nc ( n = 32/193 ) ( p < 0.0001 , table 1 ) . the difference in apoe4 carrier status between ad with comorbid dm and nc was significant ( p = 0.0001 ) . apoe4 allele frequencies were highest among ad with co - morbid dm ( 0.35 ) followed by ad without dm ( 0.25 ) , nad with dm ( 0.13 ) , nad without co - morbid dm ( 0.12 ) , and nc ( 0.08 ) . the association of ad with co - morbid dm in apoe4 carriers was more in comparison to nc with dm ( or = 5.68 , p = 0.04 , figure 1 ) . there were 17 individuals in this study who were apoe4 homozygotes14 ad , 2 nad , and one f / had . among the 14ad with homozygous apoe4 , 6 ( 42.8% ) individuals were receiving treatment for dm . in comparison , there were 84 ad who were apoe4 heterozygotes , of whom only 14 had dm ( 16.6% ) . homozygous apoe4 carriers had significantly greater comorbidity of dm and ad ( p = 0.035 ) . the present cross - sectional study evaluates the relationship between apoe4 status , ad and dm in a sample from southern india . the study also confirms the significant association between apoe4 allele and ad in the indian population [ 25 ] . the apoe4 frequency however was not associated with the age of onset of ad , or the degree of cognitive and functional ability as assessed by hmse and easi . the study also reiterates the increased association of ad and dm ( p = 0.0004 ) established by other studies [ 813 , 15 ] . interestingly , ad individuals with dm were more likely to be apoe4 carriers compared to nc with dm ( or 5.68 ) . the current study indicates a need to evaluate the role of apoe4 as a risk factor for dm in future . study in mexican americans did not find any difference in apoe4 frequency between diabetics and nondiabetics . it is interesting to note that xu et al . found a significant association between borderline dm and ad only in non - apoe4 carriers . assessment of the apoe4 status in dm without ad in the indian population would be able to provide some clarity towards this . individuals with apoe4 allele if found to have an increased risk to dm in their middle age , the combined presence of apoe4 and dm might further increase the risk of ad later . testing of this hypothesis was not feasible in the present study as it was a cross - sectional one from a geriatric clinic which caters to the needs of elderly with dementia . a prospective controlled followup study of the individuals with dm with and without apoe4 allele into old age is needed to establish the implications of this association of apoe4 , ad and dm . lack of prospective design , detailed assessment of dm and other validating phenotypes of ad like neuropsychological assessment , and imaging techniques for all the subjects are the limitations of the study . reasonable sample size , methodological rigor in diagnostic assessment , and an attempt to correlate two conditions of increasing concern in india , that is , diabetes and ad in the context of apoe4 allele are the strengths of the work . translational aspect of this association if proven is very important . in the indian context , prevalence of diabetes is on the rise . lifestyle and diet control measures to prevent dm in apoe4-positive individuals especially with homozygosity in middle age may modify / reduce the risk of alzheimer 's dementia .

objective . to evaluate the association of apolipoprotein e4 ( apoe4 ) in alzheimer 's dementia ( ad ) with comorbid diabetes mellitus ( dm ) . methods . the study included subjects with alzheimer 's dementia ( ad ) ( n = 209 ) , individuals with non - alzheimer 's dementia ( nad ) ( n = 122 ) , individuals with parental history of ad ( f / had ) ( n = 70 ) , and control individuals who had normal cognitive functions and no parental history of dementia ( nc ) ( n = 193 ) . dementia was diagnosed using international classification of diseases-10 revision ( icd-10 ) criteria . dm was assessed on the basis of self - report and/or use of antidiabetic medications . apoe genotyping was done using sequence - specific primer polymerase chain reaction . results . apoe4 allele frequencies were highest among ad with comorbid dm ( 0.35 ) followed by ad without dm ( 0.25 ) , nad with dm ( 0.13 ) , nad without comorbid dm ( 0.12 ) , and nc ( 0.08 ) . frequency of apoe4 in persons with f / had was 0.13 . the association of ad with co - morbid dm in apoe4 carriers was more in comparison to nc with dm ( or = 5.68 , p = 0.04 ) . conclusion . there is a significant association between ad with co - morbid dm and apoe4 genotype .

SECTION 1. FINDINGS. Congress makes the following findings: (1) A native of New Jersey, Jerry Lewis is a gifted comedian and has been a fixture in the entertainment community for more than 5 decades. (2) Born Joseph Levitch on March 16, 1926, in Newark, New Jersey, Jerry Lewis began his career by performing in local nightclubs. (3) With his hope of breaking into show business fading, Jerry Lewis was encouraged by his fellow comedians to continue his act, and soon thereafter, he formed a show business partnership with Dean Martin that would skyrocket both to fame. While performing with Martin in New York City, the pair was approached by a motion picture executive who offered them a contract with Paramount Pictures. They went on to make 16 major motion pictures during their 10-year partnership. (4) Jerry Lewis' talent and enthusiasm kept America laughing during some of the most turbulent periods in our history, World War II, the Cold War, and the assassinations of President John F. Kennedy and Dr. Martin Luther King, Jr. One of the most successful performers in show business, Jerry Lewis has received worldwide acclaim for his unique ability and style with both comedy and drama. He has been the star of stage, screen, radio, television, print, and recordings. He is considered among the elite in the history of comedy. (5) But aside from his comic persona, Jerry Lewis has been an active champion for the Muscular Dystrophy Association (MDA) since the early 1950s. In 1966, he began the ``Jerry Lewis MDA Labor Day Telethon,'' an annual television program that benefits children and adults affected by muscular dystrophy and related neuromuscular diseases. Now in its 41st year, the show, which is broadcast on some 200 stations nationwide, including Puerto Rico, and worldwide on the Internet, raises tens of millions of dollars annually. (6) Jerry Lewis summed up why he devotes so much of his time and energy to this cause with the words: ``I shall pass through this world but once. Any good, therefore, that I can do or any kindness that I can show to any human being let me do it now. Let me not defer nor neglect it, for I shall not pass this way again.''. (7) Jerry Lewis has received numerous awards for his outstanding service to our Nation. He was nominated for the Nobel Peace Prize for his dedication to the Muscular Dystrophy Association. (8) In June of 1978, the communications industry honored Jerry Lewis with the National Association of Television Program Executives Award of the Year for his humanitarian efforts in raising funds to combat neuromuscular diseases. Among his numerous awards are induction into the French Legion of Honor as ``Legion Commander,'' the Murray-Green Award for Community Service, the highest honor that the AFL-CIO bestows upon an individual, the American Medical Association Lifetime Achievement Award, and the Governor's Award (Emmy) from the Academy of Television Arts and Sciences. (9) In September of 1976, the United States Senate unanimously adopted a resolution expressing their appreciation of his philanthropic endeavors and in particular his fight to find a cure for muscular dystrophy. In February 2001, Jerry Lewis led a delegation of MDA scientists and clients to testify before a subcommittee of the United States Senate resulting in the introduction and subsequent passage of the MD-Care Act (Public Law 107-84; 115 Stat. 823), a first step toward securing a dramatic boost in Federal funding for research into all forms of muscular dystrophy. (10) Joining the ranks of distinguished Congressional Gold Medal recipients would be a fitting accolade to this consummate entertainer, world-renowned humanitarian and ``living legend'' who has served for some 5 decades as National Chairman of the Muscular Dystrophy Association. SEC. 2. CONGRESSIONAL GOLD MEDAL. (a) Presentation Authorized.--The President Pro Tempore of the Senate and the Speaker of the House of Representatives are authorized to make appropriate arrangements for the presentation, on behalf of Congress, of a gold medal of appropriate design to Jerry Lewis, in recognition of his outstanding service to the Nation. (b) Design and Striking.--For the purpose of the presentation referred to in subsection (a), the Secretary of the Treasury (in this Act referred to as the ``Secretary'') shall strike a gold medal with suitable emblems, devices, and inscriptions, to be determined by the Secretary. SEC. 3. DUPLICATE MEDALS. Under such regulations as the Secretary may prescribe, the Secretary may strike and sell duplicates in bronze of the gold medal struck pursuant to section 2 at a price sufficient to cover the cost thereof, including labor, materials, dies, use of machinery, and overhead expenses, and the cost of the gold medal. SEC. 4. STATUS AS NATIONAL MEDALS. (a) National Medals.--The medals struck under this Act are national medals for purposes of chapter 51 of title 31, United States Code. (b) Numismatic Items.--For purposes of sections 5134 and 5136 of title 31, United States Code, all medals struck pursuant to this Act shall be considered numismatic items. SEC. 5. AUTHORIZATION OF APPROPRIATIONS; PROCEEDS OF SALE. (a) Authorization of Appropriations.--There are authorized to be charged against the United States Mint Public Enterprise Fund, such sums as may be necessary to pay for the cost of the medals struck pursuant to this Act. (b) Proceeds of Sale.--Amounts received from the sale of duplicate bronze medals under section 3 shall be deposited in the United States Mint Public Enterprise Fund.

Authorizes the President Pro Tempore of the Senate and the Speaker of the House of Representatives to make appropriate arrangements for the presentation, on behalf of Congress, of a gold medal of appropriate design to comedian Jerry Lewis in recognition of his outstanding service to the Nation.

SECTION 1. SHORT TITLE. This Act may be cited as the ``Driver's License Modernization Act of 2002''. SEC. 2. FINDINGS. Congress finds the following: (1) The terrorist attacks of September 11, 2001, illuminated many flaws in the Nation's domestic security, especially in its identification system. (2) Drivers' licenses and identification cards issued by States have become the favored form of identity verification in the United States and are used by government agencies and private entities alike. (3) Inconsistent requirements between the States for initial identity verification and insufficient verification of identity documents have made the identification systems of States a prime target for fraud and identity theft. (4) Different designs on drivers' licenses and identification cards issued by States have created a market, including sales on the Internet, for fake cards that look real to those who are unfamiliar with the official designs. (5) Improving the security of State identification systems will require taking advantage of new technology. (6) Identification card technologies that can accommodate other government and private applications will provide the best return on the investment in the new cards. (7) It is necessary to improve the security of drivers' licenses and identification cards issued by States so that multiple licensing of individuals will be eliminated, the purchase of alcohol and tobacco products by underage individuals will be reduced, and identity theft will be severely reduced. SEC. 3. STATE DRIVER'S LICENSE AND IDENTIFICATION CARD PROGRAMS. (a) In General.--Subchapter I of chapter I of title 23, United States Code, is amended by adding at the end the following: ``Sec. 165. State driver's license and identification card programs ``(a) Definitions.--In this section, the following definitions apply: ``(1) Driver's license.--The term `driver's license' means a license issued by the motor vehicle agency of a State to an individual that authorizes the individual to operate a motor vehicle on highways. ``(2) Identification card.--The term `identification card' means an identification card issued by the motor vehicle agency of a State to an individual. ``(b) State Driver's License and Identification Card Programs.--Not later than 5 years after the date of enactment of this section, each State shall have in effect a driver's license and identification card program under which the State meets the following requirements: ``(1) Computer chips in drivers' licenses and id cards.-- ``(A) In general.--A State shall embed a computer chip in each new or renewed driver's license or identification card issued by the State. ``(B) Requirements for computer chips.--A computer chip embedded in a driver's license or identification card under this paragraph shall-- ``(i) contain, in electronic form, all text data written on the license or card; ``(ii) contain encoded biometric data matching the holder of the license or card; ``(iii) contain encryption and security software or hardware (or both) that prevents access to data stored on the chip without the express consent of the individual to whom the data applies, other than access by a Federal, State, or local agency (including a court or law enforcement agency) in carrying out its functions, or by a private entity acting on behalf of a Federal, State, or local agency in carrying out its functions; ``(iv) accept data or software written to the license or card by non-governmental devices if the data transfer is authorized by the holder of the license or card; and ``(v) conform to any other standards issued by Secretary. ``(2) Biometric data.-- ``(A) In general.--A State shall obtain biometric data for the identification of each individual to whom the State issues a new or renewed driver's license or identification card and shall maintain such data. ``(B) Requirement for biometric data.--Biometric data obtained by a State under this paragraph shall be of a type that can be matched to the license or card holder only with the express cooperation of the license or card holder. ``(3) Participation in linking of databases.-- ``(A) In general.--A State shall participate in a program to link State motor vehicle databases in order to provide electronic access by a State to information contained in the motor vehicle databases of all other States. ``(B) Requirements for information.--A State motor vehicle database shall contain, at a minimum, the following information: ``(i) All data fields printed on drivers' licenses and identification cards issued by the State, other than the encoded biometric data stored on such licenses and cards under paragraph (1). ``(ii) Biometric data obtained under paragraph (2) from each individual to whom the State issues a new or renewed driver's license or identification card. ``(iii) Motor vehicle drivers' histories, including motor vehicle violations, suspensions, and points on licenses. ``(4) Tamper-resistant security features.--A State shall include on each new or renewed driver's license or identification card issued by the State, multiple tamper- resistant security features or optical image layers, such as biometric scans, barcodes, 3D, flip, or motion imaging, to assist in visual verification that the license or card is valid. ``(5) Documentation.--A State shall adopt and implement procedures for accurately documenting the identity and residence of an individual before issuing a driver's license or identification card to the individual. ``(c) Guidelines.-- ``(1) In general.--Not later than 6 months after the date of enactment of this section, the Secretary shall issue guidelines to assist States in complying with the requirements of subsection (b). ``(2) Contents.--The guidelines issued under this subsection shall contain, at a minimum, the following: ``(A) Standards for the computer chip technology required for compliance with subsection (b)(1), including-- ``(i) standards to ensure interoperability and the ability to store multiple applications created by government agencies and private entities and transmitted to the license or card with the express consent of the license or card holder; and ``(ii) standards for the encoded biometric data that must be contained on each computer chip and requirements to ensure that such biometric data will be used only for matching the license or card to the presenter and will not be stored in a central database. ``(B) Standards for biometric data to be obtained from applicants for new or renewed State drivers' licenses and identification cards under subsection (b)(2) and standards for maintaining such data. ``(C) Standards for linking State motor vehicle databases under subsection (b)(3) and standards for the information to be contained in the databases. ``(D) Standards for security features or optical image layers to be placed on State drivers' licenses and identification cards under subsection (b)(4). ``(E) Standards for documentation of the identity and residence of an individual under subsection (b)(5), including a list of acceptable documents for establishing the identity and residence of an individual and procedures for verifying the authenticity of the documents. ``(F) Standards for a numbering system for State drivers' licenses and identification cards that prevents duplication between States and does not make use of the license or card holder's Social Security number. ``(3) Consultation.--Guidelines issued by the Secretary under this subsection shall be developed in consultation with the American Association of Motor Vehicle Administrators, the General Services Administration, and the National Institute of Standards and Technology. ``(4) Administrative procedures.--The Secretary may issue guidelines under this subsection without regard to subchapter II of chapter 5 of title 5. ``(d) Grants.-- ``(1) In general.--The Secretary may make grants to each State to assist the State in developing and implementing a driver's license and identification card program that meet the requirements of subsection (b). ``(2) Grants for linking of state motor vehicle databases.--The Secretary may make separate grants under this subsection to each State to assist the State in developing and implementing computer technologies and databases required to link State motor vehicle databases under subsection (b)(3). ``(3) Applications.--A State seeking a grant under this subsection shall submit to the Secretary an application that is in such form and contains such information as the Secretary may require. The Secretary shall evaluate such applications in the order received and award grants upon approval of an application. ``(4) Federal share.--The Federal share of the cost of activities funded using amounts from a grant received by a State under this subsection shall be 100 percent or a lesser percentage determined by the Secretary. ``(5) Technical assistance from gsa.--For purposes of section 201(a) of the Federal Property and Administrative Services Act of 1949 (40 U.S.C. 481(a)), a State carrying out activities using amounts from a grant under this section shall be treated as an executive agency and part of the Department of Transportation when carrying out such activities. For purposes of carrying out such activities, the Secretary shall, at the request of a State, enter into an agreement for the acquisition, on behalf of the State, of any goods, services, or supplies available to the Secretary from the General Services Administration, including acquisitions from prime venders. All such acquisitions shall be undertaken through the most efficient and speedy means practicable, including through electronic ordering arrangements. ``(6) Reports.--The Secretary shall require a State that receives a grant under this subsection to submit to the Secretary, not later than 1 year after the date of implementation of the activities funded using the amounts of the grant, a report on the results of the activities. ``(7) Repayment.-- ``(A) In general.--Except as provided in subparagraph (B), if the Secretary determines that a State receiving a grant under this subsection has not met the requirements of subsection (b) on or before the last day of the 5-year period beginning on the date of enactment of this section, the Secretary may require the State to repay, in whole or in part, the total amount received by the State in grants under this subsection. ``(B) Grants for linking of state motor vehicle databases.--In the case of a grant received under paragraph (2), if the Secretary determines that a State receiving the grant has not met the requirements of subsection (b)(3) on or before the last day of the 5- year period beginning on the date of enactment of this section, the Secretary may require the State to repay, in whole or in part, the total amount received by the State in grants under paragraph (2). ``(8) Authorization of appropriations.--There is authorized to be appropriated-- ``(A) $100,000,000 for making grants under paragraph (1); and ``(B) $200,000,000 for making grants under paragraph (2). Such sums shall remain available until expended. ``(e) Transition From National Driver Register.--After the last day of the 5-year period beginning on the date of enactment of this section, no amounts may be appropriated to carry out chapter 303 of title 49. The Secretary shall provide for the orderly transition from the National Driver Register maintained under such chapter 303 to the program established under subsection (b)(3).''. (b) Conforming Amendment.--The analysis for such chapter is amended by adding at the end of the items relating to subchapter I the following: ``165. State driver's license and identification card programs.''. SEC. 4. FORGERY OR FALSE USE OF DRIVER'S LICENSE OR IDENTIFICATION CARD. (a) In General.--Title 18, United States Code, is amended by inserting after chapter 123 the following: ``CHAPTER 125--STATE DRIVERS' LICENSES AND IDENTIFICATION CARDS ``Sec. ``2731. Definitions. ``2732. Forgery, fraudulent acquisition, or false use of driver's license or identification card. ``Sec. 2731. Definitions ``In this chapter, the terms `driver's license' and `identification card' have the meanings given such terms in section 165 of title 23. ``Sec. 2732. Forgery, fraudulent acquisition, or false use of driver's license or identification card ``Whoever-- ``(1) falsely makes, forges, counterfeits, mutilates, or alters any driver's license or identification card or instrument purporting to be a driver's license or identification card, with intent that the license or card may be used, ``(2) except by lawful authority, makes a template or similar device from which there may be printed a counterfeit driver's license or identification card, ``(3) obtains or assists in obtaining a driver's license or identification card through willful misrepresentation of identity, presentation of falsified identity documents such as birth certificates or passports, or other fraudulent representation, ``(4) tampers with, alters, or destroys a computer chip embedded in a driver's license or identification card or data contained on the computer chip, or ``(5) except by lawful authority, accesses data contained on a computer chip embedded in a driver's license or identification card, shall be fined under this title, imprisoned not more than 20 years, or both.''. (b) Clerical Amendment.--The table of chapters at the beginning of part I of title 18, United States Code, is amended by adding at the end the following: ``127. State drivers' licenses and identification cards..... 2731''. SEC. 5. INNOVATIVE USES PILOT PROGRAM. (a) In General.--The National Science Foundation may make grants to States for the implementation of programs that utilize computer chips embedded in drivers' licenses and identification cards (as such terms are defined in section 165 of title 23, United States Code) for innovative uses that enhance government services. (b) Innovative Uses.--The innovative uses referred to in subsection (a) may include the issuance of food stamps, voter registration, and other digital government applications that streamline and simplify State services to residents, including uses authorized under the Electronic Signatures in Global and National Commerce Act (15 U.S.C. 7001 et seq.). (c) Federal Share.--The Federal share of the cost of activities funded using amounts from a grant received under this section shall not exceed 50 percent. (d) Authorization of Appropriations.--There is authorized to be appropriated for making grants under this section $15,000,000. Such sums shall remain available until expended.

Driver's License Modernization Act of 2002 - Amends Federal highway provisions to require each State, within five years, to have in effect a driver's license and identification card program under which a State shall: (1) include in each new or renewed license or card a computer chip containing card or license text data in electronic form, biometric data on the license or card holder, and security features or optical image layers to assist in visual verification that the license or card is valid; (2) obtain and maintain such biometric data; (3) participate in a program to link State motor vehicle databases electronically; and (4) implement procedures for accurately documenting the identity and residence of an individual before issuing a license or card.Authorizes grants to each State: (1) by the Secretary of Transportation to assist in developing and implementing such program and computer technologies and databases required to link State motor vehicle databases; and (2) the National Science Foundation for implementing programs that utilize such embedded computer chips for innovative uses that enhance government services.Sets forth requirements regarding transition from the National Driver Register.Prohibits forgery or false use of, tampering with, or unlawfully accessing data in a driver's license or identification card.

we thank u. gnther for fruitful discussions , and j. kurths for drawing our attention to the topic of coherence resonance . this work was supported by deutsche forschungsgemeinschaft in frame of sfb 609 and grant no . ge 682/12 - 2 . 8 r. t. merrill , m.w . mcelhinny , and p.l . mcfadden , _ the magnetic field of the earth _ , ( academic , san diego , 1996 ) . valet and l. meynadier , nature * 366 * , 234 ( 1993 ) ; l. meynadier _ et al . _ , earth planet . sci . lett . * 126 * , 109 ( 1994 ) ; s. w. bogue and h. a. paul , geophys . lett . * 20 * , 2399 ( 1993 ) . a. cox , j. geophys . 73 * , 3247 ( 1968 ) ; j. a. tarduno , r. d. cottrell , and a. v. smirnov , science * 291 * , 1779 ( 2001 ) . r. heller , r. t. merrill , and p. l. mcfadden , phys . earth planet . inter . * 135 * , 211 ( 2003 ) . g. a. glatzmaier , annu . earth planet . sci . * 30 * , 237 ( 2002 ) . t. rikitake , proc . . soc . * 54 * , 89 ( 1958 ) ; f. plunian , p. marty , and a. alemany , proc . london , ser . a * 454 * , 1835 ( 1995 ) . p. hoyng , m. a. j. h. ossendrijver , and d. schmidt , geophys . fluid dyn . * 94 * , 263 ( 2001 ) ; d. schmitt , m. a. j. h. ossendrijver , and p. hoyng , phys . earth planet . 125 * , 119 ( 2001 ) ; p. hoyng , d. schmitt , and m. a. j. h. ossendrijver , phys . . inter . * 130 * , 143 ( 2002 ) . a. gailitis _ et al . _ , rev . phys . * 74 * , 973 ( 2002 ) . g. r. sarson and c. a. jones , phys . earth planet . inter . * 111 * , 3 ( 1999 ) . t. kato , _ perturbation theory of linear operators _ , ( springer , berlin , 1966 ) ; w. d. heiss , czech . * 54 * , 1091 ( 2004 ) ; u. gnther , f. stefani , and g. gerbeth , czech . j. phys . * 54 * , 1075 ( 2004 ) , math - ph/0407015 . f. krause and k .- h . rdler , _ mean - field magnetohydrodynamics and dynamo theory _ , ( akademie - verlag , berlin , 1980 ) . f. stefani and g. gerbeth , phys . e * 67 * , 027302 ( 2003 ) . g. rdiger and r. hollerbach , _ the magnetic universe _ , ( wiley - vch , weinheim , 2004 ) , p. 124 . a. s. pikovsky and j. kurths , phys . 78 * , 775 ( 1997 ) . t. yamazaki and h. oda , science * 295 * , 2435 ( 2002 ) ; g. consolini and p. de michelis , phys . lett . * 90 * , 058501 ( 2003 ) .

using a mean - field dynamo model with a spherically symmetric helical turbulence parameter @xmath0 which is dynamically quenched and disturbed by additional noise , the basic features of geomagnetic polarity reversals are shown to be generic consequences of the dynamo action in the vicinity of exceptional points of the spectrum . this simple paradigmatic model yields long periods of constant polarity which are interrupted by self - accelerating field decays leading to asymmetric polarity reversals . it shows the recently discovered bimodal field distribution , and it gives a natural explanation of the correlation between polarity persistence time and field strength . in addition , we find typical features of coherence resonance in the dependence of the persistence time on the noise . the earth s magnetic field is known to undergo irregular polarity reversals , with a mean reversal rate that varies from zero in the permian and cretaceous supercrons to ( 4 - 5 ) per myr in the present @xcite . typically , these reversals have an asymmetric ( saw - toothed ) shape , i.e. the field of one polarity decays slowly and recovers very rapidly with the opposite polarity , possibly to rather high intensities @xcite . a general correlation between the persistence time and the field intensity has also been suspected since long @xcite . a recent observation concerns the bimodal distribution of the earth dipole moment with two peaks at about 4 @xmath1 10@xmath2 am@xmath3 and at about twice that value @xcite . the explanation of these phenomena represents a great challenge for dynamo theory and numerics . remarkably , the last decade has seen three - dimensional numerical simulations of the geodynamo with sudden polarity reversals as one of the most impressive results ( cf . @xcite for a recent overview ) . despite the fact that those simulations exhibit many features of the earth s magnetic field quite well , and _ because they do so _ in parameter regions ( in particular for the ekman and the magnetic prandtl number ) that are far away from the real ones , there is a complimentary tradition to identify the essential ingredients of reversals within the framework of simplified dynamo models . this has been done , e.g. , in the tradition of the celebrated rikitake dynamo model of two coupled disk dynamos @xcite . another approach has been pursued by hoyng and collaborators @xcite who studied a prototype nonlinear mean - field dynamo model which is reduced to an equation system for the amplitudes of the non - periodic axisymmetric dipole mode and for one periodic overtone under the influence of stochastic forcing . interestingly , even this simple model shows sudden reversals and a poissonian distribution of the polarity persistence time . however , an essential ingredient of this model to account for the correct reversal duration and persistence time is the use of a large turbulent resistivity which is hardly justified , at least not by the recent dynamo experiments @xcite . = 8.0 cm sarson and jones @xcite had noticed the importance of the transition from non - oscillatory to oscillatory states for reversals to occur . it is our goal to understand this process in more detail by studying a simple mean - field dynamo model . we focus on the magnetic field dynamics in the vicinity of exceptional points @xcite of the spectrum of a non - selfadjoint operator . we will show that the main characteristics of earth magnetic field reversals can be attributed to the square - root character of the spectrum in the vicinity of such exceptional points , where two non - oscillatory eigenmodes coalesce and continue as an oscillatory eigenmode . our starting point is the well known induction equation @xmath4 for a mean - field dynamo with a helical turbulence parameter @xmath0 @xcite , acting in a fluid with electrical conductivity @xmath5 within a sphere of radius @xmath6 . the magnetic field has to be divergence - free,@xmath7 . henceforth , we will measure the length in units of @xmath6 , the time in units of @xmath8 , and the parameter @xmath0 in units of @xmath9 . note that for the earth we get a time scale @xmath10 kyr , giving a free decay time of 20 kyr for the dipole field . = 8.0 cm we decompose @xmath11 into a poloidal and a toroidal part , @xmath12 . the defining scalars @xmath13 and @xmath14 are expanded in spherical harmonics of degree @xmath15 and order @xmath16 with the expansion coefficients @xmath17 and @xmath18 . in order to allow for very long simulations ( to get a good statistics for the persistence time and the field amplitudes ) , we consider an @xmath19 dynamo with a radially symmetric helical turbulence parameter @xmath0 . in @xcite we had shown that such simple @xmath19 dynamos can exhibit oscillatory behaviour in case that @xmath20 changes its sign along the radius , which is not unrealistic for the earth @xcite . for spherically symmetric and isotropic @xmath0 , the induction equation decouples for each @xmath15 and @xmath16 into the following pair of equations : @xmath21 \ ; .\end{aligned}\ ] ] these equations are independent of the order @xmath16 , hence we have skipped it in the index of @xmath22 and @xmath23 . the boundary conditions are @xmath24 . in the following we restrict ourselves to the dipole field with @xmath25 ( the influence of higher multipole fields will be considered elsewhere ) . at first , we choose a particular radial profile @xmath20 which can yield an oscillatory behaviour @xcite . magnetic field saturation is ensured by quenching the parameter @xmath26 with the angular averaged dipole field energy which can be expressed in terms of @xmath27 and @xmath28 . in addition to that , we perturb the @xmath0-profile by noisy `` blobs '' which are assumed constant within a correlation time @xmath29 . in summary , @xmath26 takes the form : @xmath30 } \nonumber\\ & & + \xi_1(t ) + \xi_2(t ) \ ; r^2 + \xi_3(t ) \ ; r^3+\xi_4(t ) \ ; r^4 \ ; , \end{aligned}\ ] ] where the noise correlation is given by @xmath31 . @xmath32 is a normalized dynamo number measuring the overcriticality , @xmath33 is the noise amplitude , and @xmath34 is a constant measuring the inverse equipartition field energy . the equation system ( 1)-(3 ) is time - stepped using an adams - bashforth method with a radial grid spacing of 0.02 and a time step length of 2 @xmath1 10@xmath35 . for the following examples , the correlation time @xmath29 has been set to 0.02 , and @xmath34 has been chosen to be 0.01 . = 8.0 cm for the noise - free case ( @xmath36 ) , we show in fig . 1 the evolution of the magnetic field for different values of @xmath32 ( hereafter , field stands always for the value of @xmath37 at @xmath38 ) . at the slightly overcritical value @xmath39 we observe a nearly harmonic oscillation with a frequency close to one . with increasing @xmath32 , this frequency decreases , and at the same time the signal becomes saw - toothed ( or better : shark - fin shaped ) and eventually rectangular . at the critical point @xmath40 a phase transition to a non - oscillatory dynamo occurs , which can also be identified in the frequencies and field amplitudes shown in fig . 2 . = 8.0 cm in fig . 3 , we analyze the field evolution for @xmath41 in detail . figure 3a shows the field during one reversal , together with the growth rate and the frequency that result from the _ instantaneous _ , quenched @xmath0-profile . eight of these profiles ( at the moments 1 - 8 ) , together with the unquenched profile , are scaled by a factor @xmath42 yielding the growth rate curves of fig . 3b . these curves may help us to identify the following phases for a reversal : a slowly starting , but self - accelerating field decay in the non - oscillatory branch ( points 1 and 2 ) , followed by the actual polarity reversal in the oscillatory branch ( between points 3 and 4 ) , a fast increase of the field ( points 4 - 6 ) which results in a rapid @xmath0-quenching . this rapid quenching drives the system back to the point 8 which basically corresponds to the initial point 1 , only with the opposite field polarity . a peculiarity of our particular model is the existence of a second exceptional point beyond which the dynamo becomes non - oscillatory again ( between points 5 and 6 ) , which is , however , not crucial for the indicated reversal process . in an attempt to simplify this reversal picture , we consider in fig . 4 all growth rate curves of fig . 3b as being collapsed into a single one ( for that purpose we neglect their slight shape differences and consider only a shift ) . by this optical trick , the various phases of reversals can be visualized as a move of the actual growth rate point relative to this collapsed growth rate curve . figure 4 explains also the phase transition between oscillatory and steady dynamos and the discontinuity of the field amplitude from fig . 2 . the local maximum of the non - oscillatory branch of the growth rate curve is unstable and repels the dynamo in two different directions , depending on whether the growth rate there is negative or positive . if it is negative , the field decays , we get weaker @xmath0 quenching , and a subsequent reversal . if it is positive , the field increases , we get stronger @xmath0 quenching , hence the system moves to the left of the maximum . = 8.0 cm what happens now if we switch on the noise ? the influence of the noise is quite different for values of @xmath32 below and above @xmath43 . for @xmath44 , the noise is the only possibility to trigger a move from left of the local maximum to the right , hence the persistence time will decrease from infinity to some finite value . for @xmath45 , the noise will sometimes push the maximum above the zero growth rate line allowing the system to jump to the left of the maximum where it can stay for a while . hence , we will get an increase of the persistence time . for a moderate noise intensity @xmath46 , we depict in fig . 5 the time evolution for the values @xmath47 and @xmath48 which are slightly below and above @xmath43 , respectively . first of all , a drastic difference between the persistence times is still visible . the duration of a reversal , however , is quite identical for both values of @xmath32 , although its sensible definition is not obvious . with a side view on the real geomagnetic field ( for which the dipole component should decay approximately to the strength of the non - dipole components before a reversal can be identified ) , we tentatively define the reversal duration as the time the field spends between @xmath49 or @xmath50 of its mean intensity . in the first case we get a reversal duration of 30 kyr , in the second case of 12 kyr , which comes close to the observational facts . = 8.0 cm for both values , @xmath47 and @xmath48 , a bimodal behaviour of the dynamo can be observed in the field histograms of fig . 6 . for @xmath47 and @xmath51 , we observe a clear double peak on both polarity sides , centered approximately at @xmath52 and @xmath53 . evidently , the dynamo is mostly in the weak field state ( right of the maximum , cp . fig . 4 ) , with some excursions to the strong field state ( left of the maximum ) . with increasing @xmath33 this double peak is smeared out , leaving a very broad maximum for @xmath46 . the three histograms for @xmath48 show a maximum at the strong field value and ( although not a maximum ) a pronounced flattening at the weak field value . this means , the dynamo is mostly in the strong field state , with some intermediate stopovers in the weak field state , from where it can start a reversal . = 8.0 cm an overview about the mean persistence time @xmath54 and its normalized standard deviation @xmath55 in dependence on @xmath32 and @xmath33 is given in fig . 7 . note the drastic difference that small values of noise have on the dynamo behaviour for @xmath45 and @xmath44 . the normalized standard deviation , at least for the curves with @xmath56 , has a clear minimum around @xmath57 which represents a typical feature of _ coherence _ resonance @xcite . we only note here that recently _ stochastic _ resonance models have been discussed with view on a possible triggering of field reversals by the 100 kyr period of the earth orbit eccentricity @xcite . to summarize , our simple spherically symmetric @xmath19 dynamo model shows that asymmetric polarity reversals and bimodal field distributions are generic features of the dynamo behaviour in the vicinity of exceptional points . using only the molecular resistivity of the outer core , we get typical persistence times of the order of 200 kyr ( and larger ) , and a typical reversal duration of 10 - 30 kyr . we point out that this model is not a physical model of the earth dynamo , in particular owing to the missing north - south asymmetry of @xmath0 . nevertheless , we are convinced that the generic features of dynamos in the vicinity of exceptional points as they were illustrated in this paper can also be identified in much more elaborated dynamo models .

Shoppers made their feelings clear about an EU ban on models of more than 1,600 watts by visiting stores or online sellers in their droves The stampede to buy powerful vacuum cleaners intensified yesterday as retailers reported a fourfold surge in sales. Shoppers made their feelings clear about an EU ban on models of more than 1,600 watts by visiting stores or online sellers in their droves. Many have been stockpiling two or more high-power models to beat regulations that came into effect yesterday. The new EU directive is intended to reduce energy use, but it has infuriated the public, who say they’ll have to spend longer using the appliances. Online electrical retailer ao.com said weekly sales had soared 380 per cent compared with the first week of August. The most popular model was the 2,400-watt Bosch Pro Energy BSGL3126GB cylinder vacuum cleaner costing £99, which sold out yesterday. It currently has two models left in stock that are over 1,600 watts, but expects to have more this week. There was clear evidence of customers stockpiling vacuums, it added, particularly in the 2,000+ watt ranges, where 3 per cent of sales were generated by shoppers buying two or more. ‘We saw a huge surge in sales of corded vacuums over 1,600 watts over the weekend, with sales quadrupling,’ said head of small domestic appliances Leanne Beswick. ‘Having reviewed our stocking levels it looks like we still have a limited number of high wattage vacuum cleaners in our warehouse and we are expecting another two models to come back into stock this week.’ Sales at the Cooperative Electrical Shop over the past two weeks leapt by 129 per cent compared with the same period last year. Currys said sales were up 94 per cent compared with the same weekend 12 months ago. A spokesman added: ‘They have been flying off the shelves and that has been across the board – from uprights to cylinders.’ Scroll down for video THE OTHER HOUSEHOLD APPLIANCES IN THE EU'S SIGHTS Under threat: Food blenders may also be targeted Some 30 devices – mostly domestic electrical items – are facing overhauls to meet the EU guidelines, including: Air conditioning in cars – blamed for increasing fuel consumption although critics point out the drag created by opening a window uses more energy. Window heaters and seat heating will also be looked at. Fitness equipment – many modern exercise bikes and rowing machines use electricity to generate resistance. Hairdryers – power savings of 30 per cent may be required, although salons argue they will spend longer drying hair. Blenders – smoothies and soups may take longer to prepare if new rules are introduced. Fax machines – under scrutiny despite all but dying out in homes as people switch to email. Photocopiers, printers and scanners are on the list too. Power tools – they could face changes despite the Commission’s report stating the potential improvements are ‘small’. Lawnmowers – all types, including electrical and petrol, could be affected. Patio heaters – a key target due to the amount of energy lost. Kettles – may have to be redesigned to switch off sooner or slash surface heat loss. Toasters – they waste power if one or more slots is empty. Tesco has previously reported sales rocketing by 44 per cent over the past fortnight with models selling out including the 2,300-watt Hoover Breeze BR2306. Argos said it had seen an increase in sales despite 97 per cent of its stock being compliant with the new legislation since July. Retailers can continue selling existing stock until it runs out but they cannot import more and manufacturers are no longer allowed to produce them. Vacuums will also have to carry ratings from A to G similar to those on fridges and washing machines, explaining energy use, cleaning performance on carpets and hard floors, and dust emissions. The crackdown affects five of the seven vacuums given ‘Best Buy’ status by Which?, and the consumer watchdog last week advised people to ‘act quickly’ before stocks of powerful models run out. A 2012 report by retail analyst Mintel found 76 per cent of consumers rated suction power the most important feature when buying a vacuum. Senior household care analyst Richard Caines said: ‘I’m not 100 per cent convinced it will save a lot of energy as if a vacuum is not providing as much suction it will have to be used for longer.’ ||||| Image copyright Thinkstock Image caption The EU says most vacuum cleaners waste too much energy Mr Vacuum Cleaner has swept into the debate over the EU's import ban on high-wattage vacuum cleaners. James Brown, who runs the vacuum cleaner museum in Derbyshire, says a high wattage is no guarantee of good suction. He said plenty of appliances would clean well whilst using less than the new 1600 watt limit imposed this week. He alleged that some manufacturers increase the wattage of their appliances every few years to fool customers into thinking they will suck more strongly. Mr Brown, who calls himself Mr Vacuum Cleaner, considers himself an expert on vacuum cleaner performance. His views appear to be supported by the German official testing agency Stiftung Warentest, who told BBC News that 38 models of cleaner would work effectively within the new limits. This is at odds with the Which? report that triggered a panic-buying spree when it warned its readers that five out of seven of its best buys would fail to meet the new import standards. Experts say it is almost impossible to compare one set of tests against another, but Prof Will Stewart from the Institution of Engineering and Technology told BBC News that there was likely to be considerable room for energy efficiency improvement in engineering and design of new cleaners. 'Room for improvement' Mr Vacuum Cleaner told BBC News: "Most modern machines are built to be used for a couple of years, like mobile phones. You can't mend them so you throw them away. There are plenty of older cleaners that will outperform today's cleaners using a much lower wattage. "Often, more wattage just makes the cleaner hotter. Some of the manufacturers just keep pushing up the wattage with every new model because people will look at it and think 'that must be better because it uses more power', when that's not necessarily the case." Erika Gehrke, an expert from the independent German testers Stiftung Warentest, told BBC News that "plenty" of vacuums cleaned well whilst using less than 1600 watts. But she warned of the challenge ahead when 900 watts becomes the limit from 2017. "Only three cleaned well when using just 900 watts, but we think manufacturers can improve," she said. Image copyright Thinkstock Image caption Prof Stewart said there was less room for improvement in kettles Prof Stewart said different appliances had varying potential for efficiency improvement. Cleaners probably had substantial potential to improve, he said. "The same goes for hairdryers - it has been suggested that a hairdryer of half the wattage will take twice as much time to dry hair, but that's not right. You might be able to improve hair dryer efficiency by a factor of two. The key would probably be in improving the jet. "Kettles are different: a kettle is an element in water. There is not much room for improvement - a lower powered element will just take longer to boil." Prof Stewart said he would prefer that the EU improved efficiency labelling on appliances, rather than imposing standards. According to the European Commission, the new rules will help combat climate change and reduce energy costs by saving 19 terawatt-hours every year by 2020. That amounts to the electricity produced by more than four nuclear power plants for 5.5 million households. Which? has defended its warning to customers. It said its tests are based on several factors, including the ability to pick up super-fine sand from Arizona; collect pet hairs; keep dust inside the machine; ease of use; and noise. A Which? spokesman would not comment on whether they agreed with the EU efficiency legislation - a move which has prompted calls from some newspapers for the UK to leave the EU. Follow Roger Harrabin on Twitter @rharrabin ||||| Which? tells consumers to buy now as Best Buy cleaners fall foul of EU energy label that prohibits motors above 1,600w Consumers are being urged to buy powerful vacuum cleaners while they can after it emerged that some of the most powerful models on the market will disappear in September when a new EU rule comes into force. An EU energy label, to be introduced from 1 September, means manufacturers will not be able to make or import vacuum cleaners with a motor that exceeds 1,600 watts. The Which? consumer group said many of its Best Buy models had motor sizes that exceeded this, "so if you're in the market for a powerful vacuum, you should act quickly, before all of the models currently available sell out". The wattage will be limited to only 900 watts by 2017 – further restricting choice. Current cleaners typically boast an average of 1,800 watts. Which? warned that many of the models that appear in its Best Buy tables have motor sizes in excess of the new limit. Of seven awarded Best Buy status since January 2013, five have motors of more than 1,600 watts. A Best Buy 2,200w vacuum costs around £27 a year to run in electricity – around £8 more than the best-scoring 1,600w it has tested. The consumer group argues that the move is self-defeating – claiming that householders would simply use the less powerful models for longer to achieve the same degree of cleaning. The move has also angered manufacturers who agree the move will do nothing to make cleaners more environmentally friendly and will simply reduce efficiency in the home. For the first time, the labels will give vacuum cleaners A to G ratings for energy use, cleaning performance on carpets and hard floors, and dust emissions. The label also requires a minimum level of performance for the vacuum to be sold in the EU. But the label is self-regulating and it is unclear whether figures are being corroborated by an independent third party. Manufacturers' tests that will be used to provide the labelling information are also being questioned. Vacuums are typically tested new and empty and – unlike the testing by Which? – don't take into account loss of suction as the container fills. So manufacturers that give themselves A ratings across the board often don't do so well in independent tests. Popular cleaners that will be phased out next month by the new rule include a Miele S6210 2,000w bagged cylinder vacuum cleaner and the Panasonic bagged upright vacuum cleaner (also 2,000w). Dyson vacuum cleaners score highly in the ratings. However, the manufacturer has many concerns about flaws in the system that will ultimately be unhelpful for consumers. It is seeking a judicial review of the legislation at the European court of justice, with judgment due in December 2015. Sir James Dyson, whose company pioneered "bagless" vacuums, said he believed the label itself was a good idea, pointing out that he had never made a machine over 1,600 watts. But he said there were many engineering aspects other than the size of the machine to take into account, and he feared strong performing vacuum cleaners would be rated badly and lead the consumer to buy a machine that simply did not work efficiently. The European commission believes the new regulations will mean better vacuum cleaners for consumers. European commission spokeswoman for energy Marlene Holzner said in a blog: "As a result of the new EU eco-design and labelling regulations, consumers will also get better vacuum cleaners. In the past, there was no legislation on vacuum cleaners and companies could sell poorly performing vacuum cleaners."

– You can ban their e-cigs, you can ban their plastic bags—but do not, under any circumstances, take away the people's high-powered vacuum cleaners. Brits stocked up on supersuction devices before a EU ban went into effect yesterday, with retail sales of models 1,600 watts or higher increasing fourfold and some people wheeling out two or more units at a time, reports the Daily Mail. "They have been flying off the shelves, and that has been across the board—from uprights to cylinders," says a spokesman for the Currys electronics chain. The European Commission's rationale for the ban is to help stave off climate change and cut down on energy costs, notes the BBC. Retailers are allowed to dump the inventory they already have, but they can't import any more units, and manufacturers are banned from churning out more. But although people are complaining that less suction will mean more time pushing their vacuums around—therefore no significant reduction in energy use—a man who runs a vacuum museum in Derbyshire and goes by the name "Mr. Vacuum Cleaner" tells the BBC that high wattage doesn't guarantee great suction anyway. Sir James Dyson of the Dyson vacuum empire agrees, pointing out that his company doesn't even make a machine over 1,600 watts, but he's still worried that current regulations will hurt the industry overall and keep people from buying powerful cleaners, reports the Guardian. (See what happened to AK-47 sales when sanctions against Russia took effect.)

ALBUQUERQUE (KRQE) – Three teenagers have been charged with murder, accused of beating two homeless men to death. Albuquerque Police called it a heinous crime on Sunday, saying at least one of the suspects involved admitted that the group was targeting transients and have done it many times before. Alex Rios, 18, Nathaniel Carrillo, 16, and Gilbert Tafoya, 15, are all charged with murder. APD say the three boys beat two homeless men to death in a vacant lot on 60th and Central early Saturday morning. “Very heinous crime,” said Officer Simon Drobik of the Albuquerque Police Department. APD is still trying to identify the two men who were killed. While the crime tape has been cleared, what happened at the lot is something many officers won’t forget anytime soon. “I mean, I was sick to my stomach,” said Drobik. “It’s just horrific … kids.” According to a criminal complaint, the beating took place after the three teens said they came home from a party. “They went over there with the intent to hurt these individuals in that lot,” said Drobik. Police say someone called 911 after finding two bodies on a mattress behind a e-cigarette shop along 60th Street. Police found the bodies and shortly after, caught up with a third victim who was alive but hurt after running from the scene. “Really badly beaten, he was able to tell us that he had been beaten up in that area before and he thought he knew who the offenders were,” said Drobik. According to the criminal complaint, two of the boys involved in the case live in this home just a few hundred feet away from where the two men were found dead. Police then went to the home and quested Tafoya and Carrillo and their friend Alex Rios, who was said to be sleeping over at the home. Officers saw blood on Carillo’s pants and then asked to search the home. According to the complaint, Tafoya and Carillo’s parents consented to the search. Inside, officers found more bloody clothes and an ID card of one of the men thought to have been killed. Police then interviewed the three boys. Each admitted to having a role in the beating the men, using sticks, metal poles, bricks and cinder blocks. Tafoya even told police that the group had been attacking Albuquerque’s homeless population at random for the last year. According to the complaint, Tafoya also told police that he “estimated that they have attacked 50 people” in the last couple months. Police say that an large number of unsolved homeless beatings is not on their radar right now. “It’s hard getting some transients to come forward to express that they were victims of crime,” said Drobik. Officers are now looking for other victims, neighbors are stunned. “It’s horrible, that’s horrible,” said Charles Jones. Jones, who lives in the area, used to be homeless. He says he’s not surprised no one has come forward. “The homeless are not going to run and tell anybody because then nobody listens to us, you know?” said Jones. He hopes people will step forward, though. “They have to be held accountable for that,” said Jones. KRQE News 13 spoke to a few family members of Gilbert Tafoya and Nathaniel Carrillo at their house today, but they didn’t have a comment. The District Attorney’s Office for Bernalillo County will determine whether or not the boys will be tried as adults. ||||| .......... .......... .......... .......... .......... .......... .......... .......... .......... .......... .......... .......... .......... .......... .......... .......... .......... .......... — There is a newer version of this story: Bond set at $5M each for teen murder suspects Police said three Albuquerque teenagers took turns smashing cinder blocks on the heads of two sleeping homeless men, killing both in an attack so brutal that police haven’t been able to identify the victims. And one of the teenagers told APD police the three friends have attacked dozens of homeless people at random throughout the city in the last year. Alex Rios, 18, Nathaniel Carrillo, 16, and Gilbert Tafoya, 15, were all arrested late Saturday on two open counts of murder and other charges, according to jail records. Tafoya told police they have attacked as many as 50 homeless people in recent months, according to the criminal complaint, and police are asking possible victims to come forward. The men’s bodies were found by a passerby at 8 a.m. Saturday in a field near 60th and Central. “They are unrecognizable,” Simon Drobik, an Albuquerque Police Department spokesman, said of the victims. “My question is: Who failed these kids? How did it get to this point? It was so violent. I was sick to my stomach. Homicide (detectives) had a hard time dealing with it.” Carrillo and Tafoya lived with their father at a home just north of the empty lot where the bodies were found, according to the complaint. Police said the two men were asleep when the attack started. The teens also attacked a third man in the field, Jerome Eskeets, who had also been asleep but escaped and helped police identify the attackers, according to the complaint. He told police they wore black T-shirts over their faces as masks. As he ran, one of the teens yelled at him, Eskeets said, and that helped him recognize the youth as a nearby resident. He also told police the teenagers had attacked several homeless people in the area in recent months. Police found blood on Tafoya’s clothes and more blood on clothes found inside the home. Police also recovered a debit card and what may be the driver’s license of one of the deceased, according to the criminal complaint. The three teens told police Tafoya and his girlfriend broke up and he was upset, so they went out late Friday night looking for people to beat up, according to the complaint. In addition to the cinder blocks, the three young men also kicked and punched the two men and beat them with a metal pole and sticks, according to the complaint. “They went over there with the intent to hurt the individuals in this lot,” Drobik said at a news conference Sunday. Drobik said all three teens are facing the same charges. Rios is being held at the Metropolitan Detention Center and Carrillo and Tafoya are at a juvenile detention center. Drobik said all three will likely be tried in adult court. Richard Peralta, who lives east of where the beating happened, said several homeless people stay in the area and usually sleep and hang out in the field. “The homeless people never bother us,” he said. “They are people and deserve the same respect as you, me or whoever.” A man at Carrillo’s and Tafoya’s home on Sunday afternoon declined to comment. Because Tafoya had boasted of attacking more than 50 homeless people, Drobik said police are asking any other possible victims to come forward. “We’re are asking anybody in the social system who knows someone that expressed they have been attacked, that they reach out to those people to have them come to us and let us know what happened to them,” Drobik said. “We want justice for everyone.” People with information can contact police at 242-COPS or call Crime Stoppers. Drobik said police want to interview any homeless people attacked by the suspects so they can determine if Rios, Carrillo or Tafoya had any connection to a homeless woman who police said was intentionally run over with a truck near Second Street and Iron on June 9. “A small clue, maybe a description of a truck, could tie everything up,” Drobik said.

– Three teenagers in Albuquerque, NM, took part in the violent murder of two homeless men over the weekend, say police, who suspect the teens could be behind dozens of other attacks. Alex Rios, 18, Nathaniel Carrillo, 16, and 15-year-old Gilbert Tafoya were arrested on Saturday for the murder of two men sleeping in a vacant lot who had cinder blocks smashed on their heads in an attack that left them unrecognizable. "My question is: Who failed these kids? How did it get to this point?" a police spokesman tells the Albuquerque Journal. "It was so violent. I was sick to my stomach." A third man told police that he managed to escape the attack and recognized one of the youth as a nearby resident. A criminal complaint states that the teens told police that they had gone out looking for people to beat up because Tafoya had broken up with his girlfriend and was upset. Police say Tafoya told them they had been attacking the city's homeless population over the last year and had attacked 50 people in the last few months, KRQE reports. Police are looking for more possible victims, but it's "hard getting some transients to come forward to express that they were victims of crime," a spokesman says.

osteopoikilosis is a rare benign bone dysplasia usually incidentally found on radiographs or computed tomography ( ct ) scans . is it usually asymptomatic and characterized by multiple enostoses throughout the skeleton , but rarely there might be mild pain . it is important for clinicians to recognize the image patterns to avoid further unnecessary interventions . a 37-year - old man without major medical history presented to orthopedic outpatient clinic with multiple joint pain especially at right hip for 2 weeks . physical examination showed no limited range of motion nor focal inflammation sign . 1 ) showed multiple discrete round radio - densities , known as bone islands , scattered throughout the pelvic bone , sacrum , lumbar spines , and bilateral proximal femur . to exclude osteoblastic bone metastases , whole - body tc-99 m methylene diphosphonate bone scintigraphy with pelvis single - photon emission tomography ( spect)/ct regional scan was arranged . g ) of coronal and transverse views clearly revealed clusters of multiple , discrete , small punctuate , and hyperdense lesions without focal tc-99 m methylene diphosphonate - avid uptake throughout the pelvic bones and bilateral proximal femurs . therefore , diagnosis of osteopoikilosis was made . the right hip discomfort then gradually subsided after supportive therapy including rest and oral nonsteroidal antiinflammatory drugs . radiograph of pelvis showed multiple bone islands symmetrically distributed at the skeleton , primarily on pelvic bone , sacrum , and bilateral proximal femur . there was no obvious increased uptake on ( a ) whole body bone scan ; however , ( b d ) coronal and ( e f ) transverse views of pelvis spect / ct showed numerous sclerosing lesions devoid of significant tc-99 m mdp avid uptake . ct , computed tomography ; mdp , methylene diphosphonate ; spect , single - photon emission computerized tomography . first described in 1915 by albers - schonberg , osteopoikilosis is a benign bone condition with numerous sclerosing bone islands throughout the skeleton . it is a rare condition with incidence estimated around 1 in 50,000 , and usually without age or gender differences . the patients are usually asymptomatic and incidentally found with clusters of multiple enostoses predominantly on spongy cancellous bone on radiographs or ct scans , but up to 20% might complained of articular pain . current literatures suggest loss - of - function mutations of lem domain containing 3 ( lemd3 ) gene located on 12q might be the cause , and the mutation could also affect soft tissue and skin , resulting in melorheostosis and buschke ollendorff syndrome . however , sometimes an abnormal bone scan , usually mild , could be seen , which reflects active osseous remodeling . hybrid spect / ct images could be a good choice for differential diagnosis in unexplained bone pain in one step . furthermore , it is important for clinicians to recognize the image presentations to avoid unnecessary examinations and treatments .

abstractosteopoikilosis is a benign but rare condition characterized by bone islands throughout the osseous tissue , which could be easily confused with bone metastasis . we present a case of a 37-year - old man presented to orthopedic outpatient clinic with right hip pain for 2 weeks . there were multiple , small punctate lesions scattered throughout the skeleton on radiograph . subsequent tc-99 m methylene diphosphonate ( mdp ) bone scan with pelvic single - photon emission computed tomography ( spect)/computed tomography ( ct ) showed multiple enostoses without abnormal focal mdp uptake . therefore , clinical diagnosis was compatible with osteopoikilosis while bone metastasis was unlikely . the symptoms then improved by conservative treatments . osteopoikilosis is usually an incidental finding on radiograph or ct , and a normal mdp confirmed the diagnosis by excluding bone metastasis . it is important for clinicians to recognize the specific image features to prevent further unnecessary interventions . in addition , bone spect / ct could also make the diagnosis in one step .

Michelle Obama calls on women to rise up against Trump 'The belief you can do anything to a woman? It is cruel. It's frightening. And the truth is, it hurts. It hurts,' the first lady said in an emotional speech. First lady Michelle Obama delivered a powerful and emotional rebuke to Donald Trump on Thursday, saying his vulgar comments on sexual assault “have shaken me to my core," while calling on women to rise up against the Republican nominee. “The fact is in this election we have a candidate for president of the United States who over the course of his lifetime and the course of this campaign has said things about women that are so shocking, so demeaning, I simply will not repeat anything here today,” she said at a campaign rally in New Hampshire. “And last week we saw this candidate actually bragging about sexual assaulting women. I can't believe I'm saying that a candidate for president of the United States has bragged about sexually assaulting women.” Story Continued Below Her voice breaking at times, Obama warned the crowd that “I’m going to get a little serious here, because I think we can all agree that this has been a rough week in an already rough election.” She said remarks from Trump recorded in 2005, in which he crudely described language how his celebrity allowed him to sexually assault women without consequence, constituted “hurtful, hateful language.” “Language that has been painful for so many of us,” she continued. “Not just as women, but as parents trying to protect our children and raise them to be caring, respectful adults. And as citizens who think our nation's leaders should meet basic standards of human decency.” Trump has apologized for the language captured on the tape, on which he can be heard bragging that he would “grab [women] by the pussy,” but also chalked the remarks up to little more than “locker room talk” that did not reflect anything he had actually done. But the first lady said it was much more, describing Trump’s remarks as "a powerful individual speaking freely and openly about sexually predatory behavior." She said that the GOP nominee’s comments reminded women of being catcalled on the street or leered at by a coworker and of stories from mothers and grandmothers about what it used to be like for women in the workplace. “I listen to all of this and I feel it so personally, and I'm sure that many of you do, too, particularly the women,” Obama said. “The shameful comments about our bodies, the disrespect of our intelligence. The belief you can do anything to a woman? It is cruel. It's frightening. And the truth is, it hurts. It hurts.” “So many have worked for so many years against this kind of violence and abuse and disrespect. But here we are in 2016 we're hearing these exact same things every single day on the campaign trail,” she continued. “We are drowning in it. And all of us are doing what women have always done, we're trying to keep our heads above water. Just trying to get through it. Trying to pretend like this doesn't really bother us.” The first lady drew a clear line between normal campaign rhetoric and the type that has come from Trump. She wondered aloud what effect the Manhattan billionaire’s language about women might have on young girls, given how painful she said it had been to grown women. Likewise, she said adult men are similarly “worried about the impact this election is having on our boys who are looking for role models of what it means to be a man.” “Because let's be very clear, strong men, strong men, men who are truly role models, don't need to put down women to make themselves feel powerful,” she said. Trump’s history of degrading and derogatory remarks should be offensive to Americans of all parties, the first lady said. They dip below the level of normal political discourse, she said, and ought to be repudiated by all Americans. “I know it's a campaign, but this isn't about politics. It's about basic human decency. It's about right and wrong,” she said. “And we cannot endure this or expose our children to this any longer, not for another minute, let alone for four years. Now is the time for all of us to stand up and say, enough is enough. This has got to stop right now.” Borrowing lines from previous stump speeches on Clinton’s behalf, the first lady told the crowd that the former secretary of state “is the right person for the job because we've seen her character and commitment, not just in this campaign but over the course of her entire life.” Obama praised Clinton’s resume, reciting her laundry list of government jobs and history of public service, and also the persistence she showed as secretary of state and after losing the 2008 Democratic primary. Unlike women of previous generations, Obama told the crowd that “today we as women have all the power we need to determine the outcome of this election.” She urged those considering a vote for an alternate candidate to think what they might feel like on Nov. 9, the day after Election Day, if their refusal to vote for Clinton had helped Trump win the White House. She added that the stakes of the election are too grave for women to simply turn off the news and disengage from the election, and that Trump’s rhetoric requires action. “In this election, if we turn away from her, if we just stand by and allow her opponent to be elected, then what are we teaching our children about the values they should hold? About the kind of life they should lead. What are we saying?” she said. “In our hearts, in our hearts, we all know that if we let Hillary's opponent win this election, then we are sending a clear message to our kids that everything they're seeing and hearing is perfectly okay. We are validating it. We are endorsing it.” “We're telling our sons that it's okay to humiliate women. We're telling our daughters that this is how they deserve to be treated,” she continued. “We're telling all our kids that bigotry and bullying are perfectly acceptable in the leader of their country." Authors: ||||| Stumping for Hillary Clinton today, first lady Michelle Obama said the revelations over the last week about Trump’s treatment of women have “shaken me to my core” and called on voters not to dismiss the incident as “just another day’s headline.” “Last week we saw this candidate actually bragging about sexually assaulting women. I can’t believe I’m saying that a candidate for president of the United States has bragged about sexually assaulting women. I have to tell you that I — I can’t stop thinking about this. It has shaken me to my core in a way that I couldn’t have predicted,” Obama said at a Clinton campaign event at Southern New Hampshire University in Manchester. Growing emotional at times, the first lady urged Americans not to ignore Trump’s comments from a 2005 “Access Hollywood” interview. “This is not something that we can ignore. It’s not something we can just sweep under the rug as just another disturbing footnote in a sad election season, because this was not just a lewd conversation,” she continued. “This wasn’t locker room banter.” Obama, who has stumped for Clinton several times over the last month, has become one of Clinton’s most effective surrogates on the campaign trail, in part for her ability to effectively attack the Republican nominee without ever mentioning him directly by name. “Strong men, men who are truly role models, don’t need to put down women to make themselves feel powerful,” she said. “We need someone who will heal the wounds that divide us, someone who truly cares about us and our children.” She emphasized that she has been disturbed by the recent revelations and contrasted the political discourse with Tuesday’s Day of the Girl, an internationally recognized day celebrating girls. “I listen to all of this, and I feel it so personally, and I’m sure that many of you do too, particularly the women,” she said. “The shameful comments about our bodies, the disrespect of our ambitions and intellect, the belief that you can do anything you want to a woman. It is cruel. It’s frightening. And the truth is, it hurts. It hurts. It’s like that sickening feeling you get when you’re walking down the street, minding your own business, and some guy says out vulgar words about your body.” The first lady concluded by urging women to “roll up your sleeves” and get to work for Clinton, reminding those in attendance of the phrase that she used in her speech at the Democratic National Convention this summer — which has morphed into a campaign slogan of sorts for Clinton. Obama said, “Remember this, when they go low, we go ...” “High!” the crowd shouted.

– Donald Trump has had a bruising week with hot mics and accusations of sexual misconduct, and one person who's "shaken to the core" by the din surrounding the GOP nominee: Michelle Obama, who spoke on the matter at a Hillary Clinton campaign event Thursday in Manchester, NH, reports ABC News. "I can't believe I'm saying that a candidate for president of the United States has bragged about sexually assaulting women," she said, adding that she hasn't been able to stop thinking about it. "I have to tell you that I—I can't stop thinking about this. It has shaken me to my core in a way that I couldn't have predicted." Politico notes that the first lady's voice broke a few times as she addressed Trump's remarks, saying that type of talk was similar to other uncomfortable, harassing situations women often find themselves in, such as being catcalled on the street. She railed against the concept that "shameful comments" about women's bodies and "disrespect of our intelligence" are OK, adding, "The belief you can do anything to a woman? It is cruel. It's frightening. And the truth is, it hurts." She called on US women to rally over what she said was more than just a "lewd conversation." "It's not something we can just sweep under the rug as just another disturbing footnote in a sad election season," she said. "Now is time for us to stand up and say, enough is enough."

animals : this retrospective study population consisted of 67 dogs . all of the dogs were examined between february 2008 and october 2012 at the kitasato university veterinary teaching hospital and miyazaki university veterinary teaching hospital , japan . the data collected included breed , sex , age , weight , clinical signs and the presence or absence of symptoms of right - sided chf . results of echocardiographic examination , plasma chemical examinations and plasma measurements of anp and nt - probnp were recorded . clinically healthy dogs of both sexes ( 3 males and 13 females ) , aged 28 years and weighing 7.813.0 kg , were enrolled as study subjects . regarding examinations , the procedures followed the guideline for institutional laboratory animal care and use of the school of veterinary medicine at kitasato university . owners provided informed consent to obtain information about the current status of each animal . the dogs were divided into two groups based on the presence of clinical right - sided chf . dogs with mild to moderate heart failure ( exercise intolerance , prolonged recovery and tachypnea with exercise ) without fluid retention were classified as the negative for chf [ non - chf ] group ( n=23 ) . dogs with congestive signs , such as ascites , pleural effusion , subcutaneous edema and pericardial effusion , in combination with radiographic and echocardiographic evidence were classified in the right - sided chf group ( n=28 ) . diseased dogs with heartworm disease , tricuspid valve insufficiency and pulmonary valve insufficiency were included . heartworm disease was diagnosed by the presence of circulating microfilariae and/or a positive blood antigen test ( snap heartworm , idexx laboratories , westbrook , me , u.s.a . ) . dogs with suspected precapillary pulmonary hypertension ( ph ) were included . tricuspid valve regurgitation ( tr ) velocity > 2.8 m / sec or pulmonary valve regurgitation velocity > 2.2 m / sec concomitant with main pulmonary artery dilation without left - sided heart failure were considered precapillary ph . the medical records of untreated dogs with non - chf and right - sided chf were reviewed at the first medical examination . after all of the examinations was completed , if necessary , dogs received immediate medical treatment for heart disease . dogs with pulmonary stenosis , double - chambered right ventricle , pulmonary arterial embolization , suspected post - capillary ph ; i.e. , left - sided heart failure or concurrent systemic illness other than cardiovascular disease , were excluded from the study . radiography and echocardiography : the cardiothoracic ratio and vertebral heart score were evaluated using thoracic radiography . conventional echocardiographic and doppler examinations were performed using an ultrasonographic unit ( ie33 , philips electronics japan , tokyo , japan and eub7500 , hitachi medical , utsunomiya , japan ) with a 7.5 to 12 mhz probe . the diagnosis of tricuspid and pulmonary valve insufficiency was made based on color flow doppler echocardiographic evidence of regurgitated flow . diagnosis of vena cava syndrome was made based on echocardiographic evidence of heartworm ( small , bright parallel echoes ) in the pulmonary arterial , right atrial or right ventricular cavity . left ventricular end - diastolic internal diameter ( lvid ) and right ventricular internal diameter ( rvid ) were measured by m - mode echocardiography in the right parasternal short - axis view . the ratio of rvid to lvid ( rvid / lvid ratio ) and the ratio of rvid to body surface area ( rvid / bsa ratio ) were calculated . the ratio of main pulmonary artery to aorta ( pa / ao ratio ) was measured in the right parasternal short - axis view . pulsed doppler echocardiography was used to measure right ventricular inflow velocities with the sample volume positioned at the tip of the tricuspid valve leaflets in the left apical four - chamber view . the early diastolic ( e wave ) and atrial systolic ( a wave ) velocities of transtricuspid flow and the ratio of e wave to a wave velocities ( e / a ratio ) were measured . similarly , tr velocities and pulmonary valve regurgitation velocities were measured using continuous wave doppler echocardiography . plasma anp and nt - probnp measurements : to determine the concentrations of anp and nt - probnp , blood samples were collected from the jugular vein in tubes containing aprotinin ( for anp ) and ethylene diamine tetraacetic acid ( for nt - probnp ) , and were centrifuged immediately for 15 min at 4c and 3,500 rpm . the plasma was separated and stored at 80c . the plasma concentration of canine anp was measured with a chemiluminescent enzyme immunoassay with a human anp assay kit ( shionoria - anp , shionogi co. , osaka , japan ) [ 11 , 12 ] . plasma nt - probnp concentrations were determined using an enzyme immunoassay for canine nt - probnp ( cardiopet probnp , idexx laboratories ) . statistical analysis : normality of data was assessed with the kolmogorov spearman s nonparametric correlation analysis was applied to compare plasma anp and nt - probnp concentrations to the thoracic radiographic or echocardiographic measurements . forward stepwise regression analysis was used to determine the natriuretic peptides that correlated best with the radiographic and echocardiographic variables . receiver - operating characteristic ( roc ) analyses were used to assess the predictive accuracy of plasma natriuretic peptide concentrations for identification of dogs with or without right - sided chf . comparisons of roc curves were analyzed using a previously described method ( medcalc version 12.2.1.0 ; medcalc software , ostend , belgium ) . a p - value < 0.05 was considered to indicate significance . the diseased dogs included 26 mixed breeds , 4 golden retrievers , 3 miniature dachshunds , 3 welsh corgis , 2 beagles , 2 pomeranians , 2 toy poodles and 9 other breeds . the causes of heart diseases included 24 tricuspid valve insufficiency , 23 heartworm disease , 3 pulmonary valve insufficiency and 1 ebstein anomaly . of these , 37 dogs ( 72.5% ) were concomitant with suspected precapillary ph , which included 22 tricuspid valve insufficiency , 13 heartworm disease and 2 pulmonary valve insufficiency . in dogs with the right - sided chf , 21 dogs had ascites , 4 dogs had pleural effusion , 3 dogs had pulmonary edema , 2 dogs had subcutaneous edema , and 1 dog had pericardial effusion . the results of the physical examinations and thoracic radiographic variables of the groups are shown in table 1table 1.comparison of physical examination and thoracic radiographic variables among clinically healthy dogs and 2 groups of dogs with heart diseasehealthy controlnon - chfright - sided chfn162328sex ( males/ females)3/1310/1315/13age ( years)7.0 [ 2.08.0]10.0 [ 0.615.0]10.0 [ 3.219.0]body weight ( kg)10.1 [ 7.813.0]13.6 [ 3.423.1]10.8 [ 2.530.8]body temperature ( c)38.3 [ 37.740.1]38.6 [ 37.739.4]38.1 [ 36.239.9]respiratory rate ( /min)29 [ 2040]36.0 [ 24.042.0]48.0 [ 16.0180.0]heart rate ( beat / min)110 [ 88144]118.0 [ 72.0180.0]140.0 [ 36.0200.0]cardiothoracic ratio ( % ) 48.1 [ 42.753.3]61.3 [ 45.781.8]63.3 [ 47.178.5]vertebral heart score10.1 [ 8.810.3]11.5 [ 9.113.5]11.7 [ 10.215.6]data are described as median values [ min - max ] . healthy controls .. respiratory rate and heart rate were significantly higher in dogs with right - sided chf compared to those in healthy control dogs . the cardiothoracic ratio and vertebral heart score in both diseased groups were significantly higher than those in the healthy control group . echocardiographic data are shown in table 2table 2.comparison of echocardiographic variables among groupshealthy control ( n)non - chf ( n)right - sided chf ( n)rvid / bsa ratio2.1 [ 1.22.8 ] ( 16)2.4 [ 1.09.0 ] ( 20)4.8 [ 2.28.4 ] ( 28)rvid / lvid ratio0.3 [ 0.20.4 ] ( 16)0.5 [ 0.22.2 ] ( 20)1.1 [ 0.52.6 ] ( 28)pa / ao ratio1.0 [ 0.91.2 ] ( 15)1.2 [ 0.92.1 ] ( 21)1.4 [ 1.02.2 ] ( 28)tr velocity ( m / sec)3.9 [ 2.54.9 ] ( 12)4.6 [ 2.35.9 ] ( 24)pr velocity ( m / sec)3.2 [ 0.83.3 ] ( 9)3.4 [ 1.43.8 ] ( 19)e wave ( cm / sec)48.5 [ 25.067.0 ] ( 13)42.7 [ 24.9132.3 ] ( 16)78.2 [ 44.6123.3 ] ( 12)a wave ( cm / sec)49.1 [ 36.965.3 ] ( 13)66.4 [ 17.599.6 ] ( 15)64.4 [ 48.0120.0 ] ( 8)e / a ratio0.9 [ 0.61.4 ] ( 13)0.6 [ 0.41.9 ] ( 15)1.0 [ 0.62.0 ] ( 9)all data are described as median values [ min - max ] . a wave ; tricuspid late diastolic flow , e / a ratio ; the ratio of e wave to a wave velocities , e wave ; tricuspid early diastolic flow , pa / ao ratio ; ratio of main pulmonary artery to aorta , pr ; pulmonary valve regurgitation , rvid / bsa ratio ; ratio of right ventricular end - diastolic internal diameter to body surface area , rvid / lvid ratio ; ratio of right ventricular end - diastolic internal diameter to left ventricular end - diastolic internal diameter , tr ; tricuspid valve regurgitation . a ) p<0.05 v.s . healthy controls , b ) p<0.01 v.s . healthy controls , c ) p<0.001 v.s . non - chf .. the rvid / bsa and rvid / lvid ratios were significantly higher in dogs with right - sided chf compared to those in the healthy controls and non - chf group . the pa / ao ratio was significantly higher in dogs with both diseased groups compared to that in the healthy controls . the tr velocity was not different between the right - sided chf and non - chf groups . additionally , pulmonary valve regurgitation velocity was not different between the right - sided chf and non - chf groups . all data are described as median values [ min - max ] . a wave ; tricuspid late diastolic flow , e / a ratio ; the ratio of e wave to a wave velocities , e wave ; tricuspid early diastolic flow , pa / ao ratio ; ratio of main pulmonary artery to aorta , pr ; pulmonary valve regurgitation , rvid / bsa ratio ; ratio of right ventricular end - diastolic internal diameter to body surface area , rvid / lvid ratio ; ratio of right ventricular end - diastolic internal diameter to left ventricular end - diastolic internal diameter , tr ; tricuspid valve regurgitation . plasma anp concentrations in dogs with right - sided chf ( 116.0 pg / ml [ 28.5260.0 ] ) were significantly higher than those in healthy controls ( 24.8 [ 15.739.9 ] ) and those in the non - chf group ( 41.7 [ 8.1210.0 ] , fig . 1.plasma anp ( a ) and nt - probnp ( b ) concentrations in dogs with or without right - sided chf . plasma anp levels were higher in non - chf dogs than those in the healthy controls , but the differences were not significant . in addition , plasma nt - probnp concentrations in dogs with right - sided chf ( 6,554 pmol / l [ 1,5839,568 ] ) were significantly higher than those in the healthy controls ( 510 [ 551,252 ] ) and the non - chf dogs ( 1,643 [ 1078,411 ] , fig . plasma nt - probnp levels were higher in non - chf dogs than those in healthy controls , but the difference was not significant . plasma anp ( a ) and nt - probnp ( b ) concentrations in dogs with or without right - sided chf . plasma anp level was significantly correlated with the vertebral heart score ( r=0.65 ) , cardiothoracic ratio ( r=0.56 ) , rvid / bsa ratio ( r=0.43 ) , rvid / lvid ratio ( r=0.40 ) and pa / ao ratio ( r=0.46 ) ( table 3table 3.results of single regression analyses of natriuretic peptides and radiographic or echocardiographic measurementsanpnt - probnprrprrpcardiothoracic ratio0.560.31<0.0010.460.21<0.001vertebral heart score0.650.42<0.0010.670.45<0.001rvid / bsa ratio0.430.19<0.0010.450.21<0.001rvid / lvid ratio0.400.16<0.010.480.23<0.001pa / ao ratio0.460.21<0.0010.390.16<0.01e wave0.280.080.080.550.30<0.001a wave0.190.040.270.500.25<0.01e / a ratio0.160.030.360.01<0.010.96tr velocity0.160.030.390.380.150.03pr velocity0.06<0.010.780.310.100.14a wave ; tricuspid late diastolic flow , e / a ratio ; the ratio of e wave to a wave velocities , e wave ; tricuspid early diastolic flow , pa / ao ratio ; ratio of main pulmonary artery to aorta , r ; regression coefficient , pr ; pulmonary valve regurgitation , rvid / bsa ratio ; ratio of right ventricular end - diastolic internal diameter to body surface area , rvid / lvid ratio ; ratio of right ventricular end - diastolic internal diameter to left ventricular end - diastolic internal diameter , tr ; tricuspid valve regurgitation . ) . stepwise regression analysis showed that vertebral heart score ( f=8.5 ) , cardiothoracic ratio ( f=4.8 ) , rvid / lvid ratio ( f=3.5 ) and pa / ao ratio ( f=2.7 ) could predict plasma anp ( r=0.74 , r=0.55 ; p<0.001 ) . plasma nt - probnp level was significantly correlated with vertebral heart score ( r=0.67 ) , e wave velocity ( r=0.55 ) , a wave velocity ( r=0.50 ) , rvid / lvid ratio ( r=0.48 ) , cardiothoracic ratio ( r=0.46 ) , rvid / bsa ratio ( r=0.45 ) , pa / ao ratio ( r=0.39 ) and tr velocity ( r=-0.38 ) ( table 3 ) . stepwise regression analysis showed that vertebral heart score ( f=36.3 ) and heart rate ( f=5.8 ) could predict plasma nt - probnp ( r=0.77 , r=0.60 ; p<0.001 ) . a wave ; tricuspid late diastolic flow , e / a ratio ; the ratio of e wave to a wave velocities , e wave ; tricuspid early diastolic flow , pa / ao ratio ; ratio of main pulmonary artery to aorta , r ; regression coefficient , pr ; pulmonary valve regurgitation , rvid / bsa ratio ; ratio of right ventricular end - diastolic internal diameter to body surface area , rvid / lvid ratio ; ratio of right ventricular end - diastolic internal diameter to left ventricular end - diastolic internal diameter , tr ; tricuspid valve regurgitation . sensitivity and specificity for detecting dogs with presence or absence of right - sided chf at relevant cutoff values were determined . 35.3 pg / ml to detect non - chf had a sensitivity of 61.9% and a specificity of 81.3% . the area under the roc curve ( auc ) was 0.67 ( 95% ci , 0.49 to 0.86 ; p=0.075 , fig . 2.receiver operating characteristic curves displaying sensitivity and specificity using plasma anp ( a ) and nt - probnp ( b ) concentrations for detecting dogs without right - sided chf . ) . use of a plasma nt - probnp concentration > 595.5 pmol / l to identify non - chf had a sensitivity of 73.3% and specificity of 56.3% . the auc was 0.75 ( 95% ci , 0.57 to 0.94 ; p<0.017 , fig . diagnostic accuracies for detection of dogs with right - sided chf are shown in table 4table 4.diagnostic accuracy of natriuretic peptides to detect dogs with right - sided chfparameteranpnt - probnpcutoff value47.6 pg / ml3,003 pmol / lauc0.860.9395% ci0.770.960.860.99sensitivity ( % ) 81.388.5specificity ( % ) 75.790.3fpr ( % ) 24.39.7fnr ( % ) 18.711.5ppv ( % ) 7488npv ( % ) 8889anp ; atrial natriuretic peptide , auc ; area under the roc curve , ci ; confidence intervals , fnr ; false negative ratio , fpr ; false positive ratio , npv ; negative predictive value , nt - probnp ; n - terminal pro b - type natriuretic peptide , ppv ; positive predictive value .. use of a plasma anp concentration > 47.6 pg / ml to detect right - sided chf had sensitivity of 81.3% and specificity of 75.7% . 3.receiver operating characteristic curves displaying sensitivities and specificities when plasma anp ( a ) and nt - probnp ( b ) concentrations were used to identify dogs with right - sided chf . ) . 3,003 pmol / l to identify right - sided chf had a sensitivity of 88.5% and specificity of 90.3% . receiver operating characteristic curves displaying sensitivity and specificity using plasma anp ( a ) and nt - probnp ( b ) concentrations for detecting dogs without right - sided chf . anp ; atrial natriuretic peptide , auc ; area under the roc curve , ci ; confidence intervals , fnr ; false negative ratio , fpr ; false positive ratio , npv ; negative predictive value , nt - probnp ; n - terminal pro b - type natriuretic peptide , ppv ; positive predictive value . receiver operating characteristic curves displaying sensitivities and specificities when plasma anp ( a ) and nt - probnp ( b ) concentrations were used to identify dogs with right - sided chf . the roc curves of anp or nt - probnp levels used to diagnose right - sided chf were compared to those of thoracic radiographic and echocardiographic parameters ( table 5table 5.comparison of roc curve analysis to detect dogs with right - sided chfv.s . nt - probnpcardiothoracic ratiodifference between areas0.1090.20495% ci0.0020.2200.0870.321z statistic1.933.42p value0.0540.0006vertebral heart scoredifference between areas0.0330.13395% ci0.0640.1290.0370.229z statistic0.6652.716p value0.5060.007rvid / bsa ratiodifference between areas0.0220.09795% ci0.1090.1520.0080.185z statistic0.3242.144p value0.7460.032rvid / lvid ratiodifference between areas0.0320.06695% ci0.0860.1500.0080.139z statistic0.5291.758p value0.5970.079pa / ao ratiodifference between areas0.0220.07195% ci0.0990.1430.0090.151z statistic0.361.749p value0.7190.080e wavedifference between areas0.1460.00795% ci0.0280.3190.1290.143z statistic1.6460.104p value0.1000.917a wavedifference between areas0.0700.19295% ci0.1650.3050.0160.367z statistic0.8532.144p value0.5600.032e / a ratiodifference between areas0.0680.27095% ci0.1990.3350.0300.511z statistic0.4982.204p value0.6190.028anp ; atrial natriuretic peptide , a wave ; tricuspid late diastolic flow , e / a ratio ; the ratio of e wave to a wave velocities , e wave ; tricuspid early diastolic flow , ci ; confidence intervals , nt - probnp ; n - terminal pro b - type natriuretic peptide , pa / ao ratio ; ratio of main pulmonary artery to aorta , rvid / bsa ratio ; ratio of right ventricular end - diastolic internal diameter to body surface area , rvid / lvid ratio ; ratio of right ventricular end - diastolic internal diameter to left ventricular end - diastolic internal diameter . ) . in contrast , the auc for nt - probnp was significantly higher than the aucs for the cardiothoracic ratio , the vertebral heart score , the rvid / bsa ratio , the a wave and the e / a ratio . anp ; atrial natriuretic peptide , a wave ; tricuspid late diastolic flow , e / a ratio ; the ratio of e wave to a wave velocities , e wave ; tricuspid early diastolic flow , ci ; confidence intervals , nt - probnp ; n - terminal pro b - type natriuretic peptide , pa / ao ratio ; ratio of main pulmonary artery to aorta , rvid / bsa ratio ; ratio of right ventricular end - diastolic internal diameter to body surface area , rvid / lvid ratio ; ratio of right ventricular end - diastolic internal diameter to left ventricular end - diastolic internal diameter . right - sided chf in dogs is the clinical outcome of various congenital or acquired cardiac and pulmonary conditions , such as tricuspid valve insufficiency , heartworm disease , pulmonary artery stenosis , pulmonary disease and ph [ 8 , 15 , 16 , 18 ] . ascites is a frequent clinical symptom in right - sided chf and is concomitant with disease severity [ 5 , 16 ] . in addition , dogs with severe right - sided heart failure showed right ventricular dilation and main pulmonary artery enlargement [ 3 , 16 ] . in the present study , dogs with right - sided chf had congestive signs , which were concomitant with echocardiographic evidence of an increased rvid / bsa ratio , rvid / lvid ratio and pa / ao ratio , as well as the cardiothoracic ratio and vertebral heart score . these results were consistent with those of previous reports and were observed as typical echocardiographic and radiographic features of right - sided chf . measurement of plasma anp levels is mainly used to diagnose the severity of disease and to evaluate the prognosis , of dogs with left - sided heart failure [ 1 , 9 , 11 , 24 ] , whereas recent human clinical studies reported that the measurement of plasma anp is useful in assessing the severity of right - sided heart disease [ 10 , 33 ] . plasma anp levels were significantly elevated in human patients with right ventricular pressure overload , and the level showed a significant inverse correlation with the right ventricular ejection fraction . similarly , plasma anp concentrations are significantly higher in dogs with vena cava syndrome than those in normal dogs , which is concomitant with increased right atrial and ventricular pressure . these results have led to the speculation that circulating anp levels are regulated by the severity of right ventricular dysfunction in right - sided heart failure . however , whether plasma anp concentrations reflect the presence or absence of right - sided chf or disease severity , in dogs remains unclear . our results demonstrate that plasma anp levels were significantly elevated in dogs with right - sided chf , but were unchanged in dogs with non - chf . these results suggest that plasma anp levels increase with right - sided chf in dogs . most studies have reported that circulating nt - probnp levels are elevated in dogs with left - sided heart failure [ 4 , 25 , 26 , 31 , 32 ] . in dogs with mitral valve disease , the plasma nt - probnp concentration was significantly higher in dogs with chf than in asymptomatic dogs [ 25 , 31 ] . in addition , the plasma nt - probnp concentration was significantly elevated in dogs with symptomatic pulmonary stenosis compared to asymptomatic dogs , and the doppler - derived pulmonic pressure gradient was significantly correlated with the plasma nt - probnp concentration . these results led to the speculation that plasma nt - probnp concentrations can be useful for diagnosing and estimating the severity of right - sided chf in dogs . however , the clinical implications of plasma nt - probnp levels in dogs with or without right - sided chf have never been studied . in the present study , dogs with increased plasma nt - probnp concentration tended to have increased disease severity , and plasma nt - probnp levels were significantly elevated in dogs with right - sided chf . this is the first study to demonstrate that plasma nt - probnp measurements reflect the severity of right - sided chf in dogs . there are a few reports on plasma concentrations of cardiac biomarkers in dogs with right - sided heart failure [ 2 , 9 , 16 ] , but the diagnostic utility of plasma anp and nt - probnp concentrations in dogs with right - sided chf remains unclear . in the present study , a plasma anp level > 47.6 pg / ml and a plasma nt - probnp concentration > 3,003 pmol / l to identify dogs with right - sided chf had aucs of 0.86 and 0.93 , respectively . furthermore , the auc for nt - probnp , but not anp , was significantly higher than the aucs for the cardiothoracic ratio , vertebral heart score , rvid / bsa ratio , a wave and e / a ratio . these results indicate that the plasma nt - probnp concentration can be used to diagnose right - sided chf in dogs . although direct pulmonary arterial pressure measurement is considered the gold standard for diagnosing ph , dogs require general anesthesia to obtain an accurate pulmonary arterial pressure . in contrast , when tr > 2.8 m / sec is present , doppler echocardiography provides an estimate of ph in dogs [ 13 , 14 , 29 ] . thus , indirect pulmonary arterial pressure measurement using echocardiography has been proposed to diagnose ph in a clinical setting . previous studies have shown that plasma anp and nt - probnp concentrations were significantly elevated in dogs with severe ph ( systolic pulmonary arterial pressure > 75 mm hg ) , but were unchanged in mild ph ( < 50 mmhg ) [ 12 , 15 ] . in addition , the tr gradient in dogs with precapillary ph strongly correlates with plasma nt - probnp concentrations [ 12 , 15 ] . thus , the nt - probnp level is expected to be useful in assessing the severity of ph . in the present study , 37 dogs ( 72.5% ) with suspected precapillary ph were diagnosed ; however , the tr velocity was weakly correlated with the plasma nt - probnp level ( r=0.38 and r=0.15 ) , but not the anp . reasons for this difference of correlation coefficient may reflect the differences of underlying disease and population ; our study enrolled dogs with several etiologies of right - sided heart disease , but the previous study enrolled dogs with only ph [ 12 , 15 ] . because our study focused on investigating the relationship between right - sided chf and cardiac biomarkers , the association between ph and cardiac biomarkers should be interpreted with caution . limitations : subjects with several forms of heart disease or ph were enrolled . additional large - scale , disease matched prospective studies are necessary to explore the clinical implications of plasma natriuretic peptide levels in dogs with right - sided chf . several factors may affect plasma natriuretic peptide concentrations in dogs ; these include renal function , systemic blood pressure and gender [ 4 , 23 , 30 ] . conclusions : plasma anp and nt - probnp levels were significantly elevated in dogs with right - sided chf . an anp cutoff value > 47.6 pg / ml and nt - probnp > 3,003 pmol / l had high sensitivity and specificity for detection of right - sided chf . our results suggest that measuring these peptides , particularly nt - probnp , is simple and can be used to assess the presence of right - sided chf in dogs .

the clinical utility of plasma natriuretic peptide concentrations in dogs with right - sided congestive heart failure ( chf ) remains unclear . we investigated whether plasma levels of atrial natriuretic peptide ( anp ) and n - terminal pro b - type natriuretic peptide ( nt - probnp ) are useful for assessing the congestive signs of right - sided heart failure in dogs . this retrospective study enrolled 16 healthy dogs and 51 untreated dogs with presence ( n=28 ) or absence ( n=23 ) of right - sided chf . medical records of physical examinations , thoracic radiography and echocardiography were reviewed . the plasma concentration of canine anp was measured with a chemiluminescent enzyme immunoassay . plasma nt - probnp concentrations were determined using an enzyme immunoassay . plasma anp and nt - probnp concentrations in dogs with right - sided chf were significantly higher than in healthy controls and those without right - sided chf . the plasma nt - probnp concentration > 3,003 pmol / l used to identify right - sided chf had a sensitivity of 88.5% and specificity of 90.3% . an area under the roc curve ( auc ) was 0.93 . the auc for nt - probnp was significantly higher than the aucs for the cardiothoracic ratio , vertebral heart score , ratio of right ventricular end - diastolic internal diameter to body surface area , tricuspid late diastolic flow and ratio of the velocities of tricuspid early to late diastolic flow . these results suggest that plasma anp and nt - probnp concentrations increase markedly in dogs with right - sided chf . particularly , nt - probnp is simple and helpful biomarkers to assess the right - sided chf .

gravitational lensing has been used for nearly a decade to study faint , compact masses in our galaxy . although a large number of microlensing events have been detected , the lens masses and distances can not ( in most cases ) be determined , meaning that only statistical constraints on the lensing population may be derived from lensing surveys ( e.g. * ? ? ? * ; * ? ? ? the determination of the lens mass and distance in individual events would be of great utility towards elucidating the nature of the microlenses . an example of this is the claim by @xcite and @xcite that three long - duration events are likely massive black holes , with @xmath1 . since individual masses could not be measured for these events , statistical arguments were employed to support the claim for large masses . if confirmed , @xcite have argued that these black holes would represent a new , significant population of black holes roaming the galactic disk . the measurement of mass in microlensing events requires the determination of two quantities describing the event : ( 1 ) the lens - source relative parallax , @xmath2 , and ( 2 ) the angular einstein radius , @xmath0 @xcite . measurement of the parallax , @xmath2 , requires the observation of the lensing event from viewpoints separated by @xmath3 au . one way to do this is to observe the event simultaneously from the ground and from a satellite in solar orbit ; the space interferometry mission ( sim ) is currently planned to do precisely this for a number of future microlensing events . it is also possible to measure @xmath2 for long - duration events , with event timescales @xmath4few months , using the earth s motion around the sun to provide a distant vantage point . since @xmath5 of lensing events towards the bulge have durations @xmath6 longer than 100 days , with high quality photometry the parallax may be measured for a significant fraction of events . the angular einstein radius is extremely difficult to measure , since typical values are @xmath7 milliarcsecond ( hereafter mas ) , defying resolution by even the largest telescopes . in very rare cases ( e.g. * ? ? ? * ) , it is possible to measure @xmath0 during a caustic crossing , however generically @xmath0 can not be resolved by any single - aperture instrument . resolution of sub - milliarcsecond scales typically requires long baseline interferometers , and future instruments like sim should be able to determine @xmath0 for many events @xcite using narrow - angle astrometry . unfortunately , sim will not fly until later than 2009 . before sim flies , a number of long baseline , highly sensitive interferometers will come online , for example the keck interferometer or the very large telescope interferometer ( vlti ) . these ground - based interferometers can study microlensing events in several different ways , which we will consider in this paper . @xcite discussed how keck and vlti can measure @xmath0 using narrow - angle astrometry . @xcite have pointed out that for massive microlenses , @xmath0 becomes comparable to the resolution @xmath8 mas for @xmath9 m , @xmath10 m . this allows the study of microlensing events via the partial resolution of the lensed images . one possible method , discussed by @xcite , is the measurement of the decrement in fringe visibility as the microlensed images become resolved . in this paper , we also investigate the use of closure phase to determine the angular einstein radius @xmath0 . closure phase is free of many of the calibration issues afflicting visibility amplitude , however other concerns do arise . in the next section , we provide a review of the basics of microlensing . the following section gives an introduction to interferometry and closure phase . we then show how closure phase may be used to measure @xmath0 , and compare our method to other proposed techniques . since both keck interferometer and vlti have already observed first fringes , this method promises to be an exciting technique for the determination of @xmath0 and thereby the lens mass , in the next few years . in this section , we will focus on the case of a single lens and single ( unresolved ) source , since this describes the vast majority of lensing events . this situation was completely analyzed by @xcite , and we follow his notation here . consider the geometry shown in fig . [ lensgeom ] . this shows a source at distance @xmath11 behind a lens at distance @xmath12 . the lens has an angular einstein radius given by @xmath13 where @xmath14 is the lens mass and @xmath15 is the distance between lens and source . if the angular impact parameter between source and lens , in units of @xmath0 , is @xmath16 , then two images are produced on the sky along the lens - source axis at positions relative to the lens of @xmath17 these images are magnified relative to the intrinsic source brightness by factors @xmath18 respectively . the total magnification is the sum of these two terms , @xmath19 in general , the lens and source exhibit finite relative proper motion , meaning that the impact parameter is a function of time . usually , the relative motion is well approximated as linear in time , and can be written @xmath20 , measuring @xmath21 with respect to the time of smallest impact parameter @xmath22 . here , @xmath23 is the event timescale , the time it takes the lens to move one angular einstein radius relative to the observer - source line of sight , and @xmath24 is the unit vector on the sky along the relative velocity . eqns . [ x ] and [ a ] then give @xmath25 and @xmath26 as a function of time . an example is shown in fig . [ lensgeom ] . as noted by @xcite , the center - of - light of the two images shifts relative to the unlensed source position by @xmath27 also , note that at any given time , the separation between the two images is @xmath28 and the ratio of magnifications is @xmath29 these also become functions of time . it is apparent that the magnitude of the image motion is comparable to the angular einstein radius . for a bulge event with @xmath30 , @xmath31 kpc and @xmath32 kpc , this is roughly @xmath33 mas , and scales like @xmath34 . in comparison , the resolution of the hubble space telescope is @xmath35 mas , while the largest single aperture telescope ( the 10 m keck ) has a resolution using adaptive optics of roughly @xmath36 mas . to have any hope of measuring @xmath0 , multi - element interferometric arrays will be required . in the next sections we describe how interferometers may be applied towards microlensing . a stellar interferometer combines starlight from two or more apertures ; the resulting interference fringes can be used to derive a great deal of information about the source being observed , including the source location ( astrometry ) and intensity distribution ( imaging ) . for observations with a finite bandwidth a fringe pattern will be formed when the optical pathlengths from the star , through the instrument , to the beam combination have been equalized . given an aperture separation , called the baseline @xmath37 , and a star in the direction @xmath38 it follows from simple geometry that an additional delay @xmath39 must be introduced into one of the arms of the interferometer , given by @xmath40 where @xmath41 is any additional static delay internal to the interferometer . it follows that the differential delay @xmath42 between two stars can be used to determine the angle @xmath43 between them . using laser metrology systems it is possible to measure internal delay differences at the nanometer level , which for a long baseline interferometer corresponds to astrometric precision at the micro - arcsecond level . this is the basis for interferometric astrometry , which has been demonstrated to achieve 100 micro - arcsecond precision @xcite , and is expected in the next several years to produce measurement precision approaching 10 micro - arcseconds @xcite . the practical aspects of very high precision interferometric astrometry are beyond the scope of this paper . however , the technique is quite challenging and requires a rather complex instrument design . the instruments currently being designed and built are not expected to begin operations until at least 2004 - 2005 . in addition , due to the effects of atmospheric seeing , the very highest astrometric precision is likely only attainable by space - based interferometers . the fringe pattern measured by an interferometer can be described as a complex quantity called the visibility ( @xmath44 ) . it is related to the source brightness distribution on the sky ( @xmath45 ) via @xmath46 where @xmath47 is the wavelength of observation and @xmath38 points in the direction of the source . this relation is known as the van cittert - zernike theorem @xcite . in effect , the source intensity distribution and the the fringe visibility measured by an interferometer are related via a fourier transform . in the case of a microlensing event , as long as the individual lensed images are unresolved by the interferometer , @xmath48 can be modeled as two point sources located at @xmath49 and @xmath50 . @xmath51 defining the intensity ratio @xmath52 and @xmath53 we find @xmath54 it is useful to write this visibility in a slightly different form @xmath55 where @xmath56 the quantity @xmath57 ( or simply @xmath58 ) is usually what is measured by an optical interferometer ; it corresponds to the contrast of the observed fringes . the phase of the complex visibility is given by @xmath59 however , the phase measured by a single pair of apertures is corrupted by the effects of atmospheric turbulence on very short timescales ( in the optical and infrared @xmath60 radian in @xmath61 milliseconds ) and contains no useful information , unless it is measured simultaneously with a phase reference source that is in fact identical to the astrometry approach discussed in the previous section . it is also important to note that @xmath58 measurements are subject to a wide variety of error sources , and that most of these errors introduce _ bias _ in the measurement @xcite . that is to say that these error sources which can include instrument vibrations , polarization mismatch , optical alignment errors , and the blurring effects of atmospheric turbulence tend to _ reduce _ the measured fringe visibility amplitude . this makes calibration of measured visibilities quite challenging . modern optical interferometers measure @xmath58 for one or a few baseline orientations ; the precision attained is typically a few percent @xcite and in some cases as high as 0.3 % for bright stars under favorable conditions @xcite . unfortunately , it is not clear that the new generation of large - aperture interferometers equipped with ao systems and single - mode fiber spatial fibers will be able to attain such high visibility precision @xcite . despite the phase corruption introduced by the atmosphere , it is still possible to recover limited phase information without resorting to the technically complex phase referencing method , provided one interferometrically combines at least three apertures . in such a case one can form a quantity by multiplying the three complex visibilities formed over the three baselines . since the visibility is the fourier transform of the surface brightness distribution ( c.f . eqn [ vcz ] ) , the product of three visibilities measured over a closed triangle is the surface brightness s bispectrum @xmath62 , evaluated at @xmath63 and @xmath64 corresponding to the legs of the triangle . the phase of the measured bispectrum is known as the closure phase @xcite . the closure phase is immune to many forms of atmospheric corruption , which can be illustrated as follows : above each aperture there is a column of atmosphere with time - variable parcels of differing indices of refraction and hence optical pathlength . thus the atmosphere above each aperture contributes a time - variable phase error , giving @xmath65 where @xmath66 and @xmath67 are the phase errors associated with apertures 1 and 2 respectively , and @xmath68 is an intrinsic phase associated with the source as measured by the 1 - 2 baseline . the bispectrum is thus @xmath69 we see that the atmospheric phase errors ( as well as many other aperture - dependent phase errors ) cancel . this is a well - known result , first applied in radio interferometry @xcite . however , it is not immediately obvious what the closure phase represents . below we derive an expression relating the observed closure phase to the binary point source representing a microlensing event . assume 3 apertures , resulting in 3 baselines @xmath70 and @xmath71 . note that @xmath72 as before , we are looking at two point sources with intensity ratio @xmath73 and separation @xmath74 . on each baseline we measure a visibility @xmath75 given by equation ( [ vcz ] ) . @xmath76\end{aligned}\ ] ] the closure phase is thus @xmath77 there are a few things to note : the closure phase is always zero when @xmath78 , i.e. the source is symmetric . in addition , by taylor expanding the sine terms and recalling eqn . ( [ zerosum ] ) it is easy to show that for the case when @xmath79 @xmath80 this implies that a source must be resolved by the interferometer in order to produce a non - zero closure phase ; in the case of a partially resolved source the magnitude of the closure phase signal is very sensitive to the separation of the source components . unlike @xmath58 , the phase measured by an optical interferometer is largely unbiased by measurement noise . in other words , the phase noise is zero - mean , and can be reduced by averaging over a sufficiently long time . the snr for closure phase is given by @xcite @xmath81^{-1/2}\ ] ] as compared to that for visibility and phase , @xmath82 in the photon - noise dominated regime ( @xmath83 ) , the snr for closure phase and visibility scales as @xmath84 . however , for photon - starved sources , the snr drops precipitously as @xmath85 , even worse than the @xmath86 scaling of the visibility snr . hence it is important to check whether microlensing sources will be photon - rich or photon - starved . in the @xmath87-band ( @xmath88 m ) a 15th magnitude source produces 0.16 photons @xmath89 . thus we would expect an 8-m class telescope to collect @xmath90 photons sec@xmath91 . assuming a coherence time @xmath92msec , and a typical photon efficiency of 5% , we have @xmath93 per integration , safely in the photon rich regime when using modern low - noise detectors . in the absence of systematic errors a 3-element interferometer should achieve a closure phase precision of @xmath94 radians in 250 seconds . however , it remains to be seen if such levels can be achieved . to date , closure phase measurements have been made in the optical and near - ir by 2 groups . coast achieves a closure phase precision of @xmath95 degrees @xcite , while npoi achieves phase drifts of @xmath61 degrees hr@xmath91 , which can be calibrated to the level of 1 - 4 degrees by looking at known single stars @xcite . recent progress in integrated optics which due to their compact design are much less susceptible to systematic closure phase errors may well yield a large improvement in the achievable accuracy @xcite . we suggest that a good method to correct for systematic closure phase errors would be to measure closure phase across a range of wavelengths . given that many systematic error mechanisms give errors with a characteristic wavelength dependence that varies from that of the observed source , it should be possible to separate the signals . to illustrate , consider the case of a physical pathlength mismatch in the interferometric beam combiner , applied only to the light from one pair of apertures . such a path mismatch will give a closure phase error that is inversely proportional to wavelength . now consider the typical microlensing event ; although the lens is achromatic , from equation ( [ cubescale ] ) we see that the amplitude of the closure phase signal is inversely proportional to the cube of the wavelength . hence , measuring the closure phase at several wavelengths should allow one to solve for both the source closure phase and the internal closure phase error . clearly , this type of experiment would benefit from long baselines and wide bandwidth ; the vlti ( 200-m baseline ) and amber ( 3-aperture combination from 1 - 2.4@xmath96 m ) provide such a suitable combination @xcite . microlensing events are amenable to study by interferometers by all three methods described in the previous section . microlensing causes an astrometric excursion of the center of light of the two images given by eqn . ( [ astrometric ] ) , which may be measured using narrow angle astrometry @xcite . similarly , as the secondary image brightens , the two images become distinguishable from a single point source , causing a decrement in the visibility amplitude @xcite . lastly , during the microlensing event the distribution of flux about the center of light becomes asymmetric , giving a signal in the closure phase . to measure @xmath0 by astrometry , multiple measurements are required to map out the microlensing ellipse , while visibility and closure phase can give @xmath0 from a single measurement . now let us consider the measurement of these signals in practice . an important point to recall is that typical microlensed sources , by interferometrists standards , are faint . this has several ramifications for the measurement of the signals in astrometry , visibility , and closure phase . as the application of these techniques to optical / ir wavelengths is still a relatively new field , there is considerable uncertainty regarding the measurement precision that will be achievable . thus we will define a range of likely precisions ( for the optimist and the pessimist ) and evaluate the usefulness of the technique for each case . astrometric measurements of faint sources require the presence of a bright ( @xmath97 ) phase reference within an isoplanatic patch , typically of order 20 arcseconds in the @xmath87 band . the probability of a @xmath97 star falling within @xmath98 is roughly 17% @xcite . narrow - angle astrometry at the 100 micro - arcsecond level has already been demonstrated at pti , and it is reasonable to expect the keck and vlti to produce the specified precision of 10 - 30 microarcseconds . however , narrow - angle interferometric astrometry is the least mature of the three techniques , and hence we will consider the utility of the technique for precisions of both 100 and 10 @xmath96as . next consider measurement of the visibility amplitude for faint sources . the precision with which @xmath99 can be measured with small apertures ( single-@xmath100 , where @xmath100 is the fried parameter ) can be as good as 0.3% . however , recall that in our estimate for the number of photons per coherence time , we assumed an aperture of 8 m . since a typical fried parameter for @xmath87 band is @xmath101 cm , adaptive optics ( ao ) are required to correct distortions in the wavefront . ideally , an ao system would completely flatten the wavefront , giving uniform path delays across the aperture . this would restore the point spread function ( psf ) to the familiar airy pattern . unfortunately , ao systems are not ideal , and in practice manage to get @xmath102 of the light into a tight core , and the remainder in a diffuse halo . this strehl ratio sets the upper limit to the ( squared ) visibilities an interferometer can achieve , unless a spatial filter such as a single - mode optical fiber is used . however , such a spatial filter increases the maximum achievable visibility amplitude at the expense of losing light ( max coupling efficiency @xmath103 , @xcite ) and introducing visibility biases which depend on the strehl ratio @xcite . in principle , these effects may be calibrated by observing point sources and monitoring the ao strehl ratio in real time . in practice , such calibration is difficult and as yet unproven . at present , it is not known how well visibility amplitudes may be calibrated for large , ao - corrected apertures , but it may potentially be on the order of 5% . in summary , the expected precision in visibility amplitude ( @xmath99 ) for the keck and vlti will likely be between 0.5 and 5% ; we will consider the resulting measurement snr for both cases . lastly , we consider closure phase . as mentioned earlier , closure phase is free of many of the error sources afflicting visibility amplitude and phase . however , other systematics can arise which we have not anticipated . the current generation of interferometers have demonstrated closure phase precision at roughly the 1-degree level . however , there is no obvious reason why performance at the 0.001 radian ( or 0.06 degree ) could not be achieved , in particular since the necessary high - precision phase - measurement equipment is being developed for differential - phase detections of hot exoplanets @xcite . in addition , @xcite has discussed the possibility of detecting hot exoplanets using differential closure phase at the vlti , an application which would require closure phase measurement precision on the order of @xmath104 radians . hence we will consider the closure phase snr for both pessimistic ( 1 deg ) and optimistic ( 0.001 rad ) cases . one of the differences between the study of microlensing via astrometry , as opposed to visibility or closure phase , is that the former does not rely upon resolving the two lensed images from each other . because of this , the signal itself is independent of wavelength . however , a single astrometric measurement alone does not suffice to measure @xmath0 . in principle , at least 3 astrometric measurements are required to measure the microlensing signal and disentangle it from proper motion of the source . since visibility and closure phase do involve resolving the two images , a single measurement does suffice to give @xmath0 , and the signal is a function of @xmath105 . inserting eqns . ( [ deltas ] ) and ( [ ratio ] ) into eqn . ( [ vsq ] ) and expanding to lowest order in @xmath106 , we see that the visibility signal behaves as @xmath107 for @xmath108 . for a 3-element interferometer in an equilateral triangle , inserting eqns . ( [ deltas ] ) and ( [ ratio ] ) into eqn . ( [ phi123 ] ) gives to lowest order @xmath109 again for @xmath110 . figures [ signal ] , [ example ] and [ snr ] illustrate this . the steep dependence on the resolution means that there is a strong incentive to measure closure phase at the smallest possible wavelength . for example , the closure phase in @xmath111 band ( @xmath112 m ) is more than 10 times larger than that in @xmath87 band ( 2.2 @xmath96 m ) . an actual microlensing event will produce time - varying signals in astrometry , visibility and closure phase , analogous to the familiar time - varying photometric lightcurves . consider a typical microlensing event with a @xmath113 lens at distance @xmath114 kpc , giving @xmath115 mas . assume @xmath116 , so that the maximum magnification is @xmath117 , and the maximal brightness ratio of the images is @xmath118 . an interferometer with a 100 m baseline operating at 2.2 @xmath96 m ( @xmath87-band ) has a resolution of 4.5 mas . if we have three such baselines arranged in an equilateral triangle , they would observe the signals in astrometry , visibility , and closure phase shown in fig . [ example ] . the astrometric signal has a maximal amplitude of @xmath119 , which in this example is about 0.15 mas . the visibility , which is usually minimized at closest approach ( @xmath120 ) , is here @xmath121 . the closure phase has a maximum value of @xmath122 . with present technology , precisions of @xmath123 in @xmath99 and @xmath124 in closure phase may be achieved , so at present such events should be studied by visibility . however , advances in measurement precision and observation at shorter wavelengths can significantly enhance the signal - to - noise . in the next subsection , we consider a reasonable range for the expected instrumental performance and show how this affects the prospects for determination of @xmath0 using interferometers . mas and @xmath116 . the first panel shows the magnitude of the astrometric motion of the center of light . the second panel shows the visibility amplitude , and the third panel plots the closure phase . we have assumed a three element interferometer in an equilateral triangle , with arms of 100 m each , observing at 2.2 @xmath96 m . we also assume that earth rotation allows a maximal projection of the image separation along at least one of the baselines . [ example],title="fig:",scaledwidth=30.0% ] mas and @xmath116 . the first panel shows the magnitude of the astrometric motion of the center of light . the second panel shows the visibility amplitude , and the third panel plots the closure phase . we have assumed a three element interferometer in an equilateral triangle , with arms of 100 m each , observing at 2.2 @xmath96 m . we also assume that earth rotation allows a maximal projection of the image separation along at least one of the baselines . [ example],title="fig:",scaledwidth=30.0% ] mas and @xmath116 . the first panel shows the magnitude of the astrometric motion of the center of light . the second panel shows the visibility amplitude , and the third panel plots the closure phase . we have assumed a three element interferometer in an equilateral triangle , with arms of 100 m each , observing at 2.2 @xmath96 m . we also assume that earth rotation allows a maximal projection of the image separation along at least one of the baselines . [ example],title="fig:",scaledwidth=30.0% ] except for highly resolved events , the astrometric signal scales as @xmath125 , while the visibility signal scales as @xmath126 and the closure phase as @xmath127 . these steep scalings improve the snr in the derived einstein radius ; for example a snr of 5 in visibility translates into a snr of 10 in @xmath0 , while a closure phase snr of 5 becomes a @xmath0 snr of 15 . figure [ snr ] plots the snr in @xmath0 from astrometry , visibility and closure phase , assuming respectively optimistic errors ( left panel ) of @xmath128 m in astrometry , 0.5% in @xmath99 , and 0.001 rad in closure phase , and ( right panel ) pessimistic errors of 100 @xmath96 m astrometry , 5% visibility amplitude , and @xmath129 closure phase . if errors of 0.001 can be achieved in @xmath111 band , then events with @xmath130 mas can be measured with snr@xmath131 . the next step is to determine the brightnesses and einstein radii for typical events . figure [ events ] illustrates the properties of bulge events . the first panel shows the distribution of peak @xmath48 magnitudes ( or in cases where the peak was not observed , the brightest observed magnitude ) for events observed by the ogle collaboration during the 1997 - 1999 seasons . assuming that sources with @xmath132 can be observed interferometrically , and assuming that @xmath133 , we estimate that roughly 20% of events are bright enough to be followed up with interferometers . however , future surveys may go deeper than ogle - ii , returning a smaller fraction of bright events . next , we turn to the distribution of einstein radii . since this has not been measured , we must estimate theoretically what the distribution will be . the rate of microlensing events depends upon the properties of the lenses and source stars . we assume two types of stars , bulge stars and disk stars . for the disk stars , we use the mass function of @xcite , namely @xmath134 , with @xmath135 , and @xmath136 for @xmath137 , and @xmath138 for @xmath139 . we take @xmath140 and @xmath141 . the disk density profile is taken to be @xmath142 , where @xmath143 is the local density , @xmath144 kpc is the disk scale length , and @xmath145 again is the distance of the lens from us towards the source , taken to be at the galactic center . the velocity distribution of disk stars is taken to be a flat rotation curve @xmath146 km / s , along with velocity dispersion in each transverse direction of @xmath147 km / s . for the bulge stars , we use the mass function of @xcite , which has the same form as the disk mf but with @xmath148 , @xmath149 for @xmath150 , and @xmath151 for @xmath152 . the bulge density distribution we use is based on the barred model of @xcite , with @xmath153 $ ] , with central density @xmath154 , @xmath155 with scale lengths @xmath156 kpc , @xmath157 kpc and inclination @xmath158 . bulge stars are taken to have no net rotation and a velocity dispersion in each transverse direction of @xmath159 km / s . lenses are drawn from both the disk and bulge populations . for simplicity , we assume that all sources lie at the galactic center , with the bulge velocity distribution . we neglect the motion of the local standard of rest relative to the flat rotation at @xmath160 . the distribution of einstein radii is given in the appendix by eqn . ( [ dgdthe ] ) and eqn . ( [ vtran ] ) . using the above parameter values , the resulting rate distribution is plotted in the second panel of fig . [ events ] . clearly , a large fraction of events should have @xmath0 accessible to instruments like the keck interferometer or vlti . as mentioned earlier , for very long timescale events ( @xmath161 days ) the parallax may be measured with sufficiently high quality photometry , meaning that measurement of @xmath0 gives the mass and distance . estimating that @xmath162 of events are of sufficiently long duration , that @xmath163 are bright enough to be observed with vlti or keck , and that 1000 events are detected every year we expect to measure masses for about 15 microlensing events from the ground every year . this should be interesting for constraining the high end of the mass function . however , vlti and keck can observe many more events than just those showing parallax , if there is justification to do so for example , if such measurements could better constrain the lens properties . let us wildly speculate about a massive campaign from vlti to observe 100 events per year . the basic observable from such a campaign is the joint distribution of event timescales @xmath23 and angular einstein radii @xmath0 . an expression for @xmath164 is derived in the appendix in eqn . ( [ dgdthedte ] ) . the resulting rate distribution is plotted in fig . ( [ dgdthdt ] ) . , spaced by decades . [ dgdthdt],scaledwidth=50.0% ] a massive survey can measure a noisy sample of this distribution . to estimate how well these measurements may be used to constrain the underlying lens properties , we use the fisher matrix @xcite . for a likelihood distribution @xmath165 ( here @xmath164 ) with parameters @xmath166 , the covariance matrix of the parameters estimated by sampling @xmath165 is given by @xmath167 where the matrix * b * has elements @xmath168 and the angular brackets denote integration over possible observables ( here @xmath0 and @xmath23 ) weighted by @xmath165 . we vary eight parameters : the bulge velocity dispersion @xmath169 , mass function parameters @xmath170 , @xmath171 and @xmath172 , and the same parameters for the disk lenses . results are listed in table [ fisher ] . we find that the corresponding disk and bulge parameters are somewhat degenerate , as may be expected , but that large numbers of events can allow constraints to be placed on the bulge parameters . for example , with @xmath173 lenses the error on the slope of the high end of the bulge mass function becomes @xmath174 , and the error on @xmath175 becomes @xmath176 , sufficient to detect a break in the mass function and to localize the break position . the caveat to this statement is that we have made several simplifying approximations , for example not exploring degeneracies between the mass function parameters and the density profile parameters . .errors on parameters from measuring @xmath164 . the second column lists the adopted values for each parameter , and the third column lists the measurement errors estimated using the fisher matrix . the errors values are to be multiplied by @xmath177 , where @xmath178 is the number of bright lens events observed by the interferometer . [ fisher ] [ cols="^,^,^",options="header " , ] interferometry is poised to revolutionize the study of microlensing events . until now , microlensing has suffered the difficulty that masses of individual lenses can not be measured , severely limiting the information able to be extracted from lensing surveys . the problem has been that the two quantities needed to measure mass and distance , the relative parallax @xmath2 and the angular einstein radius @xmath0 , are not regularly measured . the parallax may be measured for long duration events with high quality photometry , however measurement of @xmath0 requires resolution on the order of a milliarcsecond , necessitating interferometers . the upcoming space interferometry mission ( sim ) should measure masses and distances for a large sample of lenses , answering the question of the microlenses nature . well in advance of sim , however , ground - based interferometers can also provide useful measurements of lensing events . as mentioned earlier , microlensed sources are generally much fainter than the typical sources studied by optical interferometers , meaning that large apertures ( @xmath179 m ) are required . both the keck interferometer and the vlti can measure visibility amplitude for microlensing events using their largest apertures , but only vlti can measure closure phase using 3 large apertures ; the keck would be required to employ one of the 1.8 m outrigger telescopes which collect considerably fewer photons . the signal measured by interferometers is a function of the einstein radius in units of the resolution , @xmath105 . because of this , there is great advantage to go to shorter wavelengths . however , shorter wavelengths require the use of adaptive optics ( ao ) systems . since ao makes the accurate calibration of visibility very difficult , but has a smaller impact on the calibration of closure phase , there are obvious advantages to using closure phase . for a numerical example , a microlensing event with @xmath180 mas could be observed at 10 @xmath96 m without ao , but @xmath181 giving a visibility signal of @xmath182 , which would be extremely challenging to distinguish from a point source . the same event observed at 2.2 @xmath96 m using ao has @xmath183 giving a closure phase signal @xmath184 which can already be measured . only a small fraction of events are expected to be bright enough ( @xmath185 ) to be observed interferometrically . however , certain fainter events may also be accessible to interferometers . if a bright ( @xmath97 ) star falls within the isoplanatic angle , then phase referencing may be employed to extend the coherence time significantly . as noted earlier , for sites with small isoplanatic patches the probability of finding a suitable bright star is poor . additionally , this technique is quite complex and as yet unproven , however in principle this could allow the study of microlensing events as faint as 20th magnitude , reaching the bright end of lmc events . phase referencing must be employed to perform narrow angle astrometry ; our results indicate that events for which phase referencing is possible may be more profitably studied with visibility or closure phase . we expect that @xmath186 events every year will be bright enough ( @xmath132 ) and have sufficiently long duration ( @xmath161 days ) to permit the measurement of mass and distance . we have shown that a fairly large fraction of events accessible to ground - based interferometers should allow measurement of @xmath0 with high signal to noise . we also investigated the prospects for a massive follow - up campaign by vlti , and found that statistical information on the @xmath0 distribution , even without individual mass measurements , can allow constraints to be placed on lens properties like their mass function . even if our estimates turn out to be overly optimistic , interferometers will still be able to elucidate the nature of claimed black hole candidates ( e.g. * ? ? ? * ; * ? ? ? @xcite have suggested that current microlensing data indicate the presence of a significant population of intermediate mass black holes roaming the galactic disk ; interferometers will be able to confirm or reject this possibility . in this paper , we have focused on ground - based interferometers , however our results apply also to space - based interferometers like the space interferometry mission ( sim ) . sim is primarily an astrometric instrument , however it can also measure fringe visibilities . nominally , the target precision expected for sim is 1% in @xmath58 ( m. shao 2002 , priv . sim s baseline is 10 m , and typical wavelengths are @xmath187 m , giving resolution of about 12 mas . hence , sim can determine @xmath0 with snr@xmath188 from visibility alone , entirely independently of the astrometric determination , for events with @xmath189 mas . from figure [ events ] we see that this comprises a large fraction of the events . the visibility measurements come for free with the astrometric measurements , and should significantly increase the precision of sim mass measurements , as long as effects such as crowding do not pose too great an obstacle . in addition to measuring @xmath0 , sim also determines @xmath2 , the lens parallax , by measuring the time of the peak of the photometric lightcurve . since the peak of the visibility signal coincides with the peak of the photometric signal , sim visibility measurements could also be used to determine @xmath2 . however , since the variation in @xmath190 is so shallow near the peak this method may not prove to be as precise as ordinary photometric parallax measurement . one of the most ( potentially ) exciting prospects is a topic we have not discussed in this paper , binary microlensing . for a binary lens system , complicated caustic structures can arise , leading in favorable cases to the production of 5 images of the source . for a spectacular example of this , see @xcite . during caustic crossings , the magnification can get exceptionally large , e.g. factors of 30 , making these events bright enough to observe with interferometers . the five images are currently unresolvable from each other , however vlti and keck offer the prospect of imaging the multi - image pattern . with a multi - aperture system ( required for closure phase ) , one obtains several visibility measurements and one closure phase at the same time , possibly allowing the reconstruction of complex events such as caustic crossings . the microlensing optical depth @xmath191 is given by @xmath192 where @xmath193 is the mass function of lenses , normalized by @xmath194 , @xmath195 is the number density of lenses , @xmath196 is the average mass and @xmath197 is the mass density of lenses . from eqn . [ thetae ] , we then have @xmath198\nonumber\\ & = & \frac{\pi c^2}{2g}{\theta_{\rm e}}^3\int_0^{r_s}dr_l \frac{r_sr_l^3}{r_s - r_l}\frac{\rho(r_l)}{\bar{m}}\frac{dn}{dm}[m({\theta_{\rm e}},r_l ) ] \label{dtaudtheta}\end{aligned}\ ] ] where @xmath199 . the optical depth distribution describes the instantaneous properties of lensing events at any given time , but we are interested in the distribution of all events . this is described by the lensing rate @xmath200 . if the transverse velocity distribution of source stars is @xmath201 , and that of the lenses is @xmath202 , we can write the lensing rate as @xcite @xmath203 where @xmath204 @xmath205 here , @xmath206 is the observer s velocity transverse to the line of sight , and @xmath207 . we assume all sources are bulge stars , with no net rotation and a velocity dispersion in each transverse direction of @xmath169 . lenses are assumed to reside either in the bulge or in the disk , with the latter population possessing a flat rotation curve @xmath160 , along with velocity dispersion in each transverse direction of @xmath208 . for bulge lenses , this gives @xmath209 as usual , the angular integral gives a bessel function , but note that it is a modified bessel function due to the lack of an @xmath210 in the exponent . thus we have @xmath211}{(1+x^2)\sigma_b^2 } \int v^2 dv \exp\left(-\frac{v^2}{2(1+x^2)\sigma_b^2}\right ) i_0\left[\frac{(1-x)v_cv}{(1+x^2)\sigma_b^2}\right]\\ & = & \sqrt{\frac{\pi}{2}}\frac{e^{-\frac{(1-x)^2v_c^2}{4(1+x^2)\sigma_b^2 } } } { \left(4(1+x^2)\sigma_b^2 \right)^{1/2 } } \left[\left ( ( 1-x)^2v_c^2 + 2(1+x^2)\sigma_b^2\right ) i_0\left(\frac{(1-x)^2v_c^2}{4(1+x^2)\sigma_b^2}\right)\right.\nonumber\\ & & \left.\hspace{2 in } + ( 1-x)^2v_c^2 i_1\left(\frac{(1-x)^2v_c^2}{4(1+x^2)\sigma_b^2}\right)\right ] \nonumber\end{aligned}\ ] ] for disk lenses , the expression is similar , with @xmath212 and @xmath213 . from eqn . ( [ gamma ] ) , the distribution of rate with respect to angular einstein radius is @xmath214\nonumber\\ & = & 4\int_0^{r_s}dr_l r_l n(r_l ) \bar{v}_t(r_l ) m({\theta_{\rm e}},r_l ) \frac{dn}{dm}\left [ m({\theta_{\rm e}},r_l ) \right ] . \label{dgdthe}\end{aligned}\ ] ] lastly , we also want the joint distribution of rate with respect to @xmath0 and @xmath23 . this is @xmath215 \int d^2v_l d^2v_s f_l({\bm v}_l ) f_s({\bm v}_s ) v_t\delta\left({t_{\rm e}}-\frac{r_l{\theta_{\rm e}}}{{t_{\rm e}}}\right).\ ] ] for bulge lenses , this is @xmath216 \frac{r_l^4{\theta_{\rm e}}^3}{{t_{\rm e}}^4}\nonumber\\&&\qquad\times \frac{\exp\left[-\frac{(r_l{\theta_{\rm e}}/{t_{\rm e}})^2+(1-x)^2v_c^2}{2(1+x^2)\sigma_b^2 } \right]}{(1+x^2)\sigma_b^2 } i_0\left[\frac{(1-x)v_cr_l{\theta_{\rm e}}/{t_{\rm e}}}{(1+x^2)\sigma_b^2}\right ] . \label{dgdthedte}\end{aligned}\ ] ] for disk lenses , the expression is similar , with @xmath212 and @xmath213 . segranan , d. , 2002 , sf2a-2002 : semaine de lastrophysique francaise , meeting held in paris , france , june 24 - 29 , 2002 , eds . : f. combes and d. barret , edp - sciences ( editions de physique ) , conference series .

interferometers offer multiple methods for studying microlensing events and determining the properties of the lenses . we investigate the study of microlensing events with optical interferometers , focusing on narrow - angle astrometry , visibility , and closure phase . after introducing the basics of microlensing and interferometry , we derive expressions for the signals in each of these three channels . for various forecasts of the instrumental performance , we discuss which method provides the best means of measuring the lens angular einstein radius @xmath0 , a prerequisite for determining the lens mass . if the upcoming generation of large - aperture , ao - corrected long baseline interferometers ( e.g. vlti , keck , ohana ) perform as well as expected , @xmath0 may be determined with signal - to - noise greater than 10 for all bright events . we estimate that roughly a dozen events per year will be sufficiciently bright and have long enough durations to allow the measurement of the lens mass and distance from the ground . we also consider the prospects for a vlti survey of all bright lensing events using a fisher matrix analysis , and find that even without individual masses , interesting constraints may be placed on the bulge mass function , although large numbers of events would be required .

one of the current experimental advances of considerable importance in the context of ultracold atoms is the demonstration of multicomponent bose - einstein condensate ( bec ) . in particular several groups have created spinor condensates of @xmath0na atoms @xcite and @xmath1rb atoms @xcite by transferring spin polarized condensates into far - off - resonance optical dipole traps , where the spin degree of freedom becomes active and the spinor nature of the condensates is manifested . the spin - mixing dynamics and its dependence on the magnetic field have been investigated in detail for both spin-1 and spin-2 condensates in a number of theoretical @xcite and experimental works @xcite . since the spin degree of freedom becomes accessible in an optical trap , the magnetic dipole - dipole interactions ( mddi ) which arise from intrinsic or induced field of magnetic dipole moment @xcite should be taken into account in addition to the isotropic @xmath2-wave contact interaction . due to their long - range and vectorial characters , the mddi may largely enrich the variety of phenomena observed in condensates . therefore this opens up new directions of research , such as the ground - state structure of spin-1 dipolar condensates in a single trap @xcite as well as the ground - state magnetic properties of spinor bec confined in deep optical lattices @xcite , where only the dipolar interactions between condensates at different sites are considered . recently , a beautiful experiment in stuttgart @xcite has demonstrated bec in a gas of chromium atoms @xmath3 , the mddi of which is a factor of 36 higher than that for alkali atoms . this achievement makes possible the studies of the anisotropic long - range interactions in degenerate quantum gases . the present paper exploits semiclassical dynamics of spin-1 dipolar condensates in a single trap and shows the time evolutions of the population imbalance and the relative phase among different spin components @xcite . this study may help us gain some insights into the properties of this dipolar spinor condensate , such as quantum phase diffusion , spontaneous magnetization @xcite and macroscopic quantum self trapping ( mqst ) . especially , mqst known as a novel nonlinear effect has already been predicted theoretically @xcite and very recently observed experimentally in double - well trap @xcite and periodic optical lattice @xcite . the self trapping effect sustains a self - maintained interwell population imbalance during the nonlinear * * * * tunneling process . here we will show that for a dipolar condensate the interplay between spin - exchange and mddi gives rise to the intercomponent mqst naturally . moreover , due to the adjustability of the mddi , the experimental observation of the mqst effect in dipolar spinor condensates can be * * * * expected**. * * the paper is organized as follows . in sec . ii we describe the dipolar spinor bec model and derive the equations of motion of semiclassical dynamics in terms of symmetry . sec . iii is devoted to the properties of the equations of motion such as spontaneous magnetization and spin - mixing dynamics . the time evolutions of the population imbalance and the relative phase among different spin components are investigated and quantum tunneling and self trapping among different spin components are examined carefully . finally , a brief summary is given in sec . we consider a spin @xmath4 dipolar condensate with @xmath5 bosons . in second quantized form , the hamiltonian @xmath6 subject to both spin - exchanging collisions @xmath7 and mddi @xmath8 reads @xcite @xmath9 with @xmath10 \widehat{\psi}_{\alpha}\left ( \mathbf{r}\right ) \nonumber\\ & + \frac{c_{0}}{2}\int d\mathbf{r}\widehat{\psi}_{\alpha}^{\dagger}\left ( \mathbf{r}\right ) \widehat{\psi}_{\beta}^{\dagger}\left ( \mathbf{r}\right ) \widehat{\psi}_{\alpha}\left ( \mathbf{r}\right ) \widehat{\psi}_{\beta } \left ( \mathbf{r}\right ) \nonumber\\ & + \frac{c_{2}}{2}\int d\mathbf{r}\widehat{\psi}_{\alpha}^{\dagger}\left ( \mathbf{r}\right ) \widehat{\psi}_{\beta}^{\dagger}\left ( \mathbf{r}\right ) \mathbf{f}_{\alpha\alpha^{\prime}}\cdot\mathbf{f}_{\beta\beta^{\prime}% } \widehat{\psi}_{\beta^{\prime}}\left ( \mathbf{r}\right ) \widehat{\psi } _ { \alpha^{\prime}}\left ( \mathbf{r}\right ) \label{1}%\end{aligned}\ ] ] and @xmath11 } , \label{2}%\end{aligned}\ ] ] where @xmath12 @xmath13 are the field annihilation operators for an atom in the hyperfine state @xmath14 the hyperfine spin @xmath15 of one single atom is expressed in the spin-1 matrix representation , and @xmath16 is the mass of the atom . a summation over repeated indices is assumed in eqs . ( [ 1 ] ) and ( [ 2 ] ) . the external trapping potential @xmath17 is spin independent for a far off - resonant optical dipole trap which makes atomic spin degree of freedom completely accessible . the two coefficients @xmath18 , @xmath19 characterize the density - density and spin - spin collisional interactions , respectively , with @xmath20 @xmath21 being the @xmath2-wave scattering length for two spin-1 atoms in the combined symmetric channel of total spin @xmath22 and the dipolar interaction parameter is @xmath23 with @xmath24 being the land @xmath25-factor , @xmath26 the bohr magneton . @xmath27 is a unit vector . for the two experimentally created spinor condensates ( @xmath0na and @xmath1rb ) , we have @xmath28 for a condensate with its symmetry axis chosen to be along the quantization axis @xmath29 ( which happens to be the most experimentally relevant cases ) , @xmath8 takes a very simple form as shown in ref . @xcite . under the single mode approximation ( sma ) , namely , @xmath30 where @xmath31 is the spin - independent condensate spatial wave function , @xmath32 is the annihilation operator for @xmath33 component , the total hamiltonian apart from a trivial term is given as @xmath34 where @xmath35\phi\left ( \mathbf{r}\right ) $ ] is assumed to be of the same value for all components . @xmath36 characterizes the spin - changing collisions and @xmath37 @xmath38 denotes the mddi with @xmath39 being the polar angle of @xmath40 . before we proceed to examine the semiclassical dynamics of @xmath41 we would like to emphasize that @xmath7 is invariant under spin rotation , i.e. , it possesses a @xmath42 symmetry in spin space @xcite . the presence of the mddi breaks this symmetry into @xmath43 , which means @xmath6 has only axial symmetry in spin space as we chosen the quantization axis along @xmath29 . in this sense the mddi plays a similar role to that of an external magnetic field . in the mean - field theory the condensate is usually considered to be in a coherent state @xcite @xmath44 where @xmath45 is the vacuum state . the complex numbers @xmath46 are nothing but the macroscopic wave functions for the atoms in the hyperfine level @xmath47 with population @xmath48 and phase @xmath49 i.e. , @xmath50 the time - dependent variational principle of the system @xmath51 gives rise to the hamiltonian equations of motion in complex coordinates @xmath52 with @xmath53 . \label{8}%\end{aligned}\ ] ] note that the dynamics governed by hamiltonian ( [ 3 ] ) conserves the total atom numbers @xmath54 and the total hyperfine spin of the condensate in the direction of the quantization axis _ _ @xmath55 in terms of the following canonical variables @xmath56{l}% \varphi_{1}=\frac{\left ( \theta_{1}+\theta_{0}+\theta_{-1}\right ) } { 3}\\ \varphi_{2}=\theta_{0}-\frac{\left ( \theta_{1}+\theta_{-1}\right ) } { 2}\\ \varphi_{3}=\theta_{1}-\theta_{-1}% \end{array } \text { and } % \begin{array } [ c]{l}% \omega_{1}=n_{1}+n_{0}+n_{-1}\\ \omega_{2}=\frac{2}{3}n_{0}-\frac{1}{3}\left ( n_{1}+n_{-1}\right ) \\ \omega_{3}=\frac{\left ( n_{1}-n_{-1}\right ) } { 2}% \end{array } \label{9}%\ ] ] the hamiltonian ( [ 8 ] ) becomes cyclic in the coordinates @xmath57 and @xmath58 @xmath59}. \label{10}%\end{aligned}\ ] ] two important consequences follow as a result of the cyclic coordinates @xmath57 and @xmath60 firstly the mean value of the total number of atoms @xmath61 and that of the total hyperfine spin of the condensate @xmath62 are constants of motion . the dynamics , on the other hand , involves only one pair of variables @xmath63 as @xmath64 define @xmath65 @xmath66 and @xmath67 , we obtain@xmath68 that means not only @xmath69 but also @xmath70 are involved in the dynamics . the variables @xmath69 and @xmath71 are canonically conjugate in a classical hamiltonian @xmath72 in a simple mechanical analogy , @xmath73 describes a nonrigid pendulum . the bose josephson junction ( bjj ) tunneling current between different spin components is given by @xmath74 where @xmath75 . it differs from bjj tunneling current of two weakly linked bec in a double - well potential in its further nonlinearity in @xmath69 @xcite . we firstly study the equilibrium configurations of the system . they are determined by the classical equations of motion ( [ 11 ] ) after setting the time derivative terms to zero@xmath76}. \label{15}%\end{aligned}\ ] ] we have defined a dimensionless parameter @xmath77 characterizing the relative interaction strength of the mddi . in eq . ( [ 15 ] ) plus sign corresponds to the case of @xmath78 while minus sign corresponds to @xmath79 ( in the following we take the former case as an example)@xmath80 from the definition of @xmath81 we know that the constant of motion @xmath70 takes values in the interval @xmath82 and the dynamic variable @xmath69 in the interval @xmath83 in the following discussion about the solutions of the equilibrium equations we separately consider three cases in order to see more clearly how these solutions depend on the relative phase @xmath71 . \(1 ) equilibrium configuration with @xmath84 ( or @xmath85)@xmath80 the equilibrium value of @xmath69 is thus given by equation ( [ 15 ] ) with @xmath86 which has only one solution in the interval @xmath87 when @xmath88 the equilibrium value of @xmath69 approaches its upper boundary @xmath89 . in this case the fractions of atoms @xmath90 ( @xmath91 ) occupying three hyperfine states are @xmath92 @xmath93 @xmath94 @xmath80 on the other hand when @xmath95 @xmath69 is at the lower boundary @xmath96 where the fractions of atoms occupying the hyperfine states are @xmath97 @xmath98 @xmath99 besides , when @xmath100 the equilibrium value of @xmath69 is @xmath101 in the interval @xmath102 and the occupation fractions of three hyperfine states are respectively @xmath103 @xmath104 \(2 ) equilibrium configuration with @xmath105 ( or @xmath106)@xmath80 now the equilibrium value of @xmath69 is given by equation ( [ 15 ] ) with @xmath107 similarly it has again only one solution in the interval @xmath108 when @xmath109 @xmath110 @xmath69 is at the lower boundary @xmath111 in particular , when @xmath100 the solution only exists for vanished dipole - dipole interaction @xmath112 . \(3 ) equilibrium configuration with @xmath113 ( or equilibrium configuration which does not depend on the phase @xmath71)_. _ in this case there exist two solutions which are independent of the value of @xmath114 one solution appears at the lower boundary @xmath115 and the occupation fractions are @xmath116 the other one appears at the upper boundary @xmath117 and the occupation fractions are @xmath118 @xmath93 @xmath119 interestingly when @xmath120 the occupation fractions become @xmath121 and @xmath122 corresponding to the polar state of the condensate . the mean field theory predicted a polar ground state of spinor bec for @xmath123na in which the atoms interact antiferromagnetically with each other in the absence of the mddi @xcite . the intrinsic magnetic moment of particles may , however , contribute together to form a bose - einstein ferromagnetism ( bef ) @xcite . spinor bosons carry magnetic moments @xmath124 and @xmath125 represents the magnetization . spontaneous magnetization means that @xmath16 remains finite even if the external magnetic field @xmath126 vanishes , namely , the ground state of spinor bec is always ferromagnetic state . our calculations prefer the latter scenario . specifically , above results suggest that for most given values of @xmath127 and initial relative phase among the three components , when @xmath128 and @xmath129 we have @xmath16 @xmath130 , i.e. , the system is magnetized spontaneously once the dipolar spinor bec is realized . as mentioned in ref . @xcite , one can provide a direct way of confirming spontaneous magnetization experimentally . considering that both the sign and the magnitude of the mddi coefficient @xmath131 depend on the geometric shape of the condensate @xcite , we can conveniently adjust the trap aspect ratio to manipulate the magnetic property of its ground state . a key feature of dipolar spinor bec is that besides the usual two - body repulsive hard - core interactions , there also exist spin - exchange interaction and mddi which lead to spin mixing within the condensates . population can be transferred from one spin state to another under internal nonlinear interactions without the presence of external fields . insight into the complex dynamics of our system can be gained by employing the method of action - angle variables @xcite . in the subsequent section we present some numerical results and show the time evolutions of the population imbalance and the relative phase among different spin components for two cases a ) @xmath100 and b ) @xmath132 i.e. , whether total hyperfine spin of the condensate is zero or not . time has been rescaled in units of @xmath133 in figures 1 and 2 . figure 1 shows solutions of the population imbalance and relative phase of eqs . ( [ 11 ] ) with initial conditions @xmath134 @xmath135 @xmath136 for the relative interaction parameters @xmath137 @xmath138 and @xmath139 , respectively . the left column exhibits the time evolutions of the population imbalance between @xmath140 and @xmath141 components . josephson sinusoidal oscillations are observed as @xmath142 increases in figs . 1a , 1b . in fig . 1c , there is a critical transition point for @xmath143 . increasing @xmath127 further for example to @xmath144 , the population of each equivalent component oscillates around a nonzero time averaged value , which gives a net population imbalance @xmath145 . this is closely related to the mqst phenomenon . simultaneously , the right column shows the time evolutions of the relative phase between @xmath140 and @xmath141 components and indicates that as @xmath142 increases @xmath146 varies from a monotonically increasing function of time to a periodically oscillating function of time . in the nonrigid pendulum analogy , this corresponds that the motion of our system is turned from running - phase modes ( figure 1a ) into @xmath147-phase modes ( figures 1b-1d ) or from a rotation into a vibration . here the definitions of running - phase modes and @xmath147-phase modes are the same as those for two weakly coupled bec @xcite . this critical behavior depends on @xmath148 $ ] , as can be easily found from the energy conservation constraint and the boundness of the tunneling energy in eq . ( [ 12 ] ) . in fact , the value @xmath149 is inaccessible at any time * * * * if @xmath150 when @xmath151 the critical parameter is @xmath152 and @xmath153 marks the regime of mqst . specifically for @xmath154 @xmath135 the critical parameter is @xmath155 we take @xmath156 and see mqst does set in . in figure 2 we show solutions of eqs . ( [ 11 ] ) with initial conditions @xmath134 @xmath157 @xmath158 for parameters @xmath142 @xmath159 and @xmath160 respectively . the left column shows again the time evolutions of the population imbalance between @xmath140 and @xmath141 components and indicates that @xmath161 is always a periodic function of time as @xmath142 decreases . for @xmath162 the population difference is self locked to the initial value , which serves as another sign of the mqst phenomenon . the right column shows the time evolution of the relative phase between @xmath140 and @xmath141 components and indicates that as @xmath142 decreases @xmath163 is always a periodic function of time around its mean value @xmath164 . the dynamics corresponds to zero - phase modes . moreover we observe that mqst occurs when @xmath165 while * * * * for @xmath166 mqst never happens . therefore it is obvious that the spin - mixing dynamics depends on the relative interaction parameter @xmath142 and is also sensitive to the initial occupations and relative phases of the three components , which can be adjusted by engineering raman pulses @xcite . in practical experiments there are usually two different ways to achieve mqst . in figures 1 and 2 , @xmath167 and @xmath168 are kept constants while @xmath142 varies ( by changing the geometry of condensates ) . on the other hand , one can calibrate the initial values of the population imbalance @xmath169 with a fixed trap geometry ( i.e. , @xmath142 remains constant ) and @xmath168 @xcite . in order to further characterize the evolution of the system we summarize the full dynamic behavior of eq . ( [ 11 ] ) in figure 3 that shows the @xmath170-@xmath146 phase portrait with constant energy contour . the distinction between the two dynamic regimes nonlinear josephson tunneling and mqst becomes more apparent in figure 3 . in the regime of josephson oscillation the dynamic variables follow a closed phase space trajectory , while in the self - trapping regime they follow an open trajectory with an unbounded phase . we are inspired by the great expectation that tuning the contact interaction between cold atoms close to zero by feshbach resonance @xcite will make the mddi more prominent or even the dominant interaction @xcite . based on the experimental values of the @xmath2-wave scattering lengths for @xmath0na , @xmath171 and @xmath172 with @xmath173 being the bohr radius @xcite , the ratio of coefficients @xmath131 and @xmath174 can be shown to be @xmath175 , while for @xmath1rb(@xmath176 and @xmath177 ) it is @xmath178 @xcite . evaluation with a simple variational wave function @xcite gives @xmath179 for a sodium condensate up to @xmath180 atoms confined in an optical dipole trap with a very small trapping volume ( @xmath181 @xmath182 ) @xcite . on the other hand , as argued in refs . @xcite , both the sign and the magnitude of the mddi @xmath112 can be greatly tuned with trapping geometry . as has been shown @xcite , @xmath183 depends on a monotonically increasing function of the condensate aspect ratio @xmath184 , bounded between @xmath185 and @xmath186 . this clearly shows the possibility of adjusting the mddi very close to spin exchange interaction , i.e. @xmath187 . at this point our parameter @xmath142 may take values in a large scale and the manifestation of mqst is within reach with current technologies . we point out although for all of the alkali - metal atomic condensations the mddi is rather weak compared to the contact potential , the experimental achievement of bec with transition - metal chromium @xmath3 provides us the hope because the mddi here is 36 times stronger than that of alkali atoms . for these reasons , a degenerate quantum gas with adjustable long- and short - range interactions can be experimentally realized in near future . by altering the strengths of two kinds of interactions and the initial conditions , the nonlinear tunneling dynamics of dipolar spinor bec consequently sustains a self - maintained population imbalance : a novel mqst effect . such a scheme would avoid the difficulty of realizing experimentally the double - well magnetic trap . in summary we have described a semiclassical treatment of the spin-1 dipolar spinor condensates . as a result of the conservation of atom numbers and total hyperfine spin of the condensate , the classical equations of motion are derived and discussed in a similar way as in double - well bjj . it is demonstrated that spontaneous magnetization and spin - mixing dynamics depend on * * * * both * * * * the spin - exchange interaction @xmath188 and the mddi @xmath112 through the ratio @xmath189 the initial population imbalance , the relative phase among the three components of the condensate as well as the total hyperfine spin of the system all play important roles in the semiclassical dynamics . finally we have indicated the possibility of using dipolar spinor condensate as a platform for practical manipulation of mqst and josephson oscillation . this work was supported by national natural science foundation of china under grant nos.10475053 , 10175039 and 90203007 . d. m. stamper - kurn , m. r. andrews , a. p chikkatur , s. inouye , h .- j . miesner , j. stenger , and w. ketterle , phys . 80 , 2027 ( 1998 ) ; j. stenger , s. inouye , d. m. stamper - kurn , h .- j . miesner , a. p. chikkatur and w. ketterle , nature 396 , 345 ( 1998 ) . h. schmaljohann , m. erhard , j. kronjger , m. kottke , s. van staa , l. cacciapuoti , j. j. arlt , k. bongs , and k. sengstock , phys . 92 , 040402(2003 ) ; m .- s . chang , c. d. hamley , m. d. barrett , j. a. sauer , k.m . fortier , w . zhang , l. you , and m. s. chapman , phys . rev . 92,140403(2004 ) ; t. kuwamoto , k. araki , t. eno , and t. hirano , phys . rev . a 69 , 063604(2004 ) ; j. m. higbie , l. e. sadler , s. inouye , a. p. chikkatur , s. r. leslie , k. l. moore , v. savalli , d. m. stamper - kurn , cond - mat/0502517 . c. k. law , h. pu , and n. p. bigelow , phys . 81 , 5257(1998 ) ; h. pu , c. k. law , s. raghavan , j. h. eberly , and n. p. bigelow , phys . rev . a 60 , 1463(1999 ) ; hiroki saito , masahito ueda , cond - mat/0504398 ; wenxian zhang , d. l. zhou , m. -s . chang , m. s. chapman , l. you , cond - mat/0502061 . * figure captions * + figure 1 : spin - mixing dynamics : the population imbalance @xmath69 and relative phase @xmath71 versus time for initial conditions @xmath190 @xmath135 @xmath191 and @xmath192 @xmath193 @xmath194 @xmath195 @xmath196 @xmath197 and @xmath139 @xmath198 . time is rescaled in units of @xmath199 figure 3 : constant energy contours in a phase - space plot of population imbalance @xmath69 versus phase difference @xmath71 . the upper panel : @xmath204 and @xmath205 ( @xmath206 ) . the lower panel : @xmath207 and @xmath208 ( @xmath209 ) . dark areas mean lower energy .

we study the semiclassical dynamics of a spinor condensate with the magnetic dipole - dipole interaction included . the time evolution of the population imbalance and the relative phase among different spin components depends greatly on the relative strength of interactions as well as on the initial conditions . the interplay of spin exchange and dipole - dipole interaction makes it possible to manipulate the atomic population on different components , leading to the phenomena of spontaneous magnetization and macroscopic quantum self trapping . simple estimate demonstrates that these effects are accessible and controllable by modifying the geometry of the trapping potential .

SECTION 1. SHORT TITLE. This Act may be cited as the ``State Court Interpreter Grant Program Act of 2012''. SEC. 2. FINDINGS. Congress finds that-- (1) the fair administration of justice depends on the ability of all participants in a courtroom proceeding to understand that proceeding, regardless of their English proficiency; (2) 21 percent of the population of the United States over 5 years of age speaks a language other than English at home; (3) only qualified and certified court interpreters can ensure that persons with limited English proficiency comprehend judicial proceedings in which they are a party; (4) the knowledge and skills required of a qualified court interpreter differ substantially from those required in other interpretation settings, such as social service, medical, diplomatic, and conference settings; (5) the Federal Government has demonstrated its commitment to equal administration of justice, regardless of English proficiency; (6) regulations implementing title VI of the Civil Rights Act of 1964 (42 U.S.C. 2000d et seq.), as well as the guidance issued by the Department of Justice pursuant to Executive Order 13166, issued August 11, 2000, clarify that all recipients of Federal financial assistance, including State courts, are required to take reasonable steps to provide meaningful access to their proceedings for persons with limited English proficiency; (7) 43 States have developed, or are developing, qualified court interpreter programs; (8) a robust and effective court interpreter program-- (A) actively recruits skilled individuals to serve as court interpreters; (B) trains those individuals in the interpretation of court proceedings; (C) develops and uses a thorough, systematic certification process for court interpreters; (D) has sufficient funding to ensure that a qualified and certified interpreter will be available to the court whenever necessary; and (E) efficiently uses funding to create substantial cost savings; and (9) Federal funding is necessary to-- (A) encourage State courts that do not have court interpreter programs to develop them; (B) assist State courts with nascent court interpreter programs to implement them; (C) assist State courts with limited court interpreter programs to enhance them; and (D) assist State courts with robust court interpreter programs to make further improvements and share successful cost saving programs with other States. SEC. 3. STATE COURT INTERPRETER PROGRAM. (a) Grants Authorized.-- (1) In general.--The Administrator of the Office of Justice Programs of the Department of Justice (referred to in this section as the ``Administrator'') shall make grants, in accordance with such regulations as the Attorney General may prescribe, to State courts to develop and implement programs to assist individuals with limited English proficiency to access and understand State court proceedings in which they are a party. (2) Use of grants.--A State court may use a grant awarded under this subsection to-- (A) develop or enhance a court interpreter program for the State court; (B) develop, institute, and administer language certification examinations; (C) recruit, train, and certify qualified court interpreters; (D) pay for salaries, transportation, and technology necessary to implement the court interpreter program developed or enhanced under subparagraph (A); (E) provide for remote interpretation services to facilitate certified court interpretations when costs prohibit in-person interpretation; or (F) engage in other related activities, as prescribed by the Attorney General. (b) Application.-- (1) In general.--The highest State court of each State seeking a grant under this section shall submit an application to the Administrator at such time, in such manner, and accompanied by such information as the Administrator may reasonably require. (2) Contents.--The highest State court of each State submitting an application under paragraph (1) shall include in the application-- (A) a demonstration of need for the development, implementation, or expansion of a State court interpreter program; (B) an identification of each State court in that State that would receive funds from the grant; (C) the amount of funds that each State court identified under subparagraph (B) would receive from the grant; and (D) the procedures that the highest State court would use to directly distribute grant funds to State courts identified under subparagraph (B). (c) State Court Allotments.-- (1) Base allotment.--From amounts appropriated for each fiscal year pursuant to section 5, the Administrator shall allocate $100,000 to the highest court of each State that has an application approved under subsection (b). (2) Additional allotment.-- (A) In general.--From amounts appropriated for each fiscal year pursuant to section 5, the Administrator shall allocate $5,000,000 to be distributed among the highest State courts that-- (i) have an application approved under subsection (b); and (ii) are located in a State with extraordinary needs that prevent the development, implementation, or expansion of a State court interpreter program. (B) Determining need.--In determining whether a State has extraordinary needs required under subparagraph (A), the Administrator shall consider-- (i) based on data from the Bureau of the Census, the ratio between the number of people over 5 years of age who speak a language other than English at home and identify as speaking English less than very well-- (I) in that State; and (II) in all of the States that receive an allocation under paragraph (1); and (ii) any efficiency or substantial cost savings expected from a State court interpreter program. (C) Priority consideration.--In allocating amounts under subparagraph (A), the Administrator shall give priority to any State that does not have and has not begun to develop a qualified court interpreter program. (d) Treatment of District of Columbia.--For purposes of this section-- (1) the District of Columbia shall be treated as a State; and (2) the District of Columbia Court of Appeals shall act as the highest State court for the District of Columbia. SEC. 4. REPORT. Not later than 1 year after the date on which the first grant is made under section 3, the Administrator shall submit a report to Congress that describes how each highest State court has used the funds from each grant made under section 3 in a manner consistent with section 3(a)(2). SEC. 5. AUTHORIZATION OF APPROPRIATIONS. There are authorized to be appropriated $10,000,000 for each of fiscal years 2013 through 2017 to carry out this Act.

State Court Interpreter Grant Program Act of 2012 - Directs the Administrator of the Office of Justice Programs of the Department of Justice (DOJ) to make grants to state courts to develop and implement programs to assist individuals with limited English proficiency to access and understand state court proceedings in which they are a party. Authorizes the use of grant awards by state courts to: (1) develop or enhance a court interpreter program; (2) develop, institute, and administer language certification examinations; (3) recruit, train, and certify qualified court interpreters; (4) pay for salaries, transportation, and technology necessary to implement the court interpreter program; (5) provide for remote interpretation services to facilitate certified court interpretations when costs prohibit in-person interpretation; or (6) engage in other activities prescribed by the Attorney General.

SECTION 1. SHORT TITLE. This Act may be cited as the ``Fairness for Homeowners Act of 2007''. SEC. 2. ORIGINATIONS OF CONSUMER CREDIT TRANSACTIONS SECURED BY THE CONSUMER'S PRINCIPAL DWELLING. (a) In General.--The Truth in Lending Act (15 U.S.C. 1601 et seq.) is amended by inserting after section 129 the following new section: ``Sec. 129A. Originations of consumer credit transactions secured by the consumer's principal dwelling ``(a) Definitions.--For purposes of this section, the following definitions shall apply: ``(1) Fully indexed rate.--The term `fully indexed rate' equals the index rate prevailing at the time a consumer credit transaction secured by a consumer's principal dwelling is originated, plus the margin that will apply after the expiration of an introductory interest rate. ``(2) Mortgage broker.--The term `mortgage broker' means any person who is defined as a mortgage broker under applicable State law. ``(b) Requirements for Originators.-- ``(1) Ability to pay.-- ``(A) In general.--No creditor or mortgage broker may make, provide, or arrange for any consumer credit transaction secured by a consumer's principal dwelling without verifying the consumer's reasonable ability to pay the scheduled payments of the following, as applicable: principal; interest; real estate taxes; homeowner's insurance, assessments, and mortgage insurance premiums. ``(B) Variable interest rate.--In the case of any consumer credit transaction secured by a consumer's principal dwelling for which the applicable annual percentage rate may vary over the life of the credit, the reasonable ability to pay shall be determined, for purposes of this paragraph, on the basis of a fully indexed rate plus 200 basis points and a repayment schedule which achieves full amortization over the life of the extension of credit. ``(C) Verification of consumer income and financial resources.--In the case of any consumer credit transaction secured by a consumer's principal dwelling, the income and financial resources of the consumer shall be verified for purposes of this paragraph by tax returns, payroll receipts, bank records, or other similarly reliable documents. ``(D) Other criteria.--No provision of this paragraph shall be construed as prohibiting reliance on criteria other than a consumer's income and financial resources to establish the reasonable ability of the consumer to repay any consumer credit transaction secured by the consumer's principal dwelling, to the extent such other criteria are also verified through reasonably reliable methods and documentation. ``(E) Consumer statement is insufficient proof.--A statement by a consumer of the consumer's income or financial resources shall not be sufficient to establish the existence of any income or financial resources when verifying the reasonable ability of the consumer to repay any consumer credit transaction secured by the consumer's principal dwelling, for purposes of this paragraph. ``(2) Prohibition on steering.--No creditor or mortgage broker may make, provide, or arrange for any consumer credit transaction secured by a consumer's principal dwelling that is of a lower investment grade if-- ``(A) the consumer's credit score; or ``(B) comparable underwriting data, in any case in which the creditor or mortgage broker does not utilize credit scoring or a credit score for the consumer is unavailable, indicates that the borrower may qualify for a consumer credit transaction, available from or through the creditor or mortgage broker, that is of a higher investment grade. ``(3) Prohibition on prepayment penalties for arms.-- ``(A) In general.--In the case of any consumer credit transaction secured by a consumer's principal dwelling that provides for variable rates of interest on the credit extended under the transaction, the transaction may not contain terms under which a consumer must pay a prepayment penalty for paying all or part of the principal before the date on which the principal is due. ``(B) Exclusion for jumbo mortgages.--Subparagraph (A) shall not apply to any consumer credit transaction secured by a consumer's principal dwelling the principal amount (as defined in subsection (c)(2)) of which exceeds the maximum dollar amount limitation (for a residence of the applicable size) on the amount of the principal obligation of a mortgage for a 1- to 4- family residence that may be purchased by the Federal Home Loan Mortgage Corporation, as then in effect pursuant to section 305(a)(2) of the Federal Home Loan Mortgage Corporation Act. ``(c) Limitation on Financed Points, Charges, and Fees.-- ``(1) In general.--No creditor or mortgage broker may, in connection with any consumer credit transaction secured by the consumer's principal dwelling, include in the principal amount of such transaction any portion of any qualified finance charge in excess of the amount which is equal to 5 percent of the principal amount of the transaction. ``(2) Definitions.--For purposes of this subsection, the following definitions shall apply: ``(A) Qualified finance charge.--The term `qualified finance charge' means the sum of-- ``(i) the finance charge as determined under section 106, minus any interest and time price differential; and ``(ii) all compensation paid to a mortgage broker from any source in connection with this transaction. ``(B) Principal amount.--The term `principal amount' means-- ``(i) in the case of any consumer credit transaction under an open end credit plan secured by the consumer's principal dwelling, the maximum amount of credit that may be extended under the terms of such plan as determined without taking into account any amount included in determining the finance charge under section 106; and ``(ii) in the case of any other consumer credit transaction secured by a consumer's principal dwelling, the amount financed (as defined in section 138(a)(2)). ``(3) Prohibition on excessive finance charges.--No creditor or mortgage broker may, in connection with any consumer credit transaction secured by the consumer's principal dwelling, impose or receive any amount included in determining the qualified finance charge for such transaction that exceeds the amount which is equal to 5 percent of the principal amount of the transaction. ``(4) Exception.--This subsection shall not apply to any consumer credit transaction secured by the consumer's principal dwelling that is ensured or guaranteed by the Secretary of Housing and Urban Development, the Secretary of Veterans Affairs, or the Farmers Home Administration. ``(d) Mortgage Broker Duties of Agency.-- ``(1) In general.--Any mortgage broker acting to obtain or arrange for any consumer credit transaction secured by the consumer's principal dwelling shall be considered to have an agency relationship with the consumer in all cases by operation of law and shall comply with the following duties: ``(A) Mortgage brokers shall act in the consumer's best interest and in the utmost good faith toward each consumer and shall not compromise a consumer's right or interest in favor of another's right or interest, including a right or interest of the mortgage broker. ``(B) A mortgage broker shall not accept, give, or charge any undisclosed compensation or realize any undisclosed remuneration, either through direct or indirect means, that inures to the benefit of the mortgage broker on an expenditure made for the consumer. ``(C) Mortgage brokers shall carry out all lawful instructions given by the consumer. ``(D) Mortgage brokers shall disclose to consumers all material facts of which the mortgage broker has knowledge which might reasonably affect the consumer's rights, interests, or ability to receive the consumer's intended benefit from the consumer credit transaction, but not facts which are reasonably susceptible to the knowledge of the consumer. ``(E) Mortgage brokers shall use reasonable care in performing duties. ``(F) Mortgage brokers shall account to a consumer for all the consumer's money and property received as agent. ``(2) Scope.--The duty of agency between mortgage broker and consumer applies when the mortgage broker is acting in the capacity of mortgage broker providing mortgage brokerage services with respect to any consumer credit transaction secured by the consumer's principal dwelling for which the broker is not the creditor. ``(3) Rules of construction.-- ``(A) Fees for services rendered.--No provision of this subsection shall be construed as prohibiting a mortgage broker from contracting for or collecting a fee for services rendered which had been disclosed to the consumer in advance of the provision of such services. ``(B) Duty of broker.--No provision of this subsection shall be construed as requiring a mortgage broker-- ``(i) to obtain or arrange for any consumer credit transaction secured by the consumer's principal dwelling on behalf of a consumer that contains terms or conditions not available to the mortgage broker in the mortgage broker's usual course of business; or ``(ii) to obtain or arrange for any consumer credit transaction secured by the consumer's principal dwelling from a creditor with whom the mortgage broker does not have a business relationship. ``(e) Independent Verification of Consumer Counseling Before Refinancing Special Mortgages.-- ``(1) In general.--No creditor or mortgage broker may make, provide, or arrange for any consumer credit transaction secured by the consumer's principal dwelling all or a portion of the proceeds of which are used to fully or partially pay off a special mortgage unless the borrower has obtained a written certification from an authorized independent loan counselor that the borrower has received counseling on the advisability of the transaction. ``(2) Definitions.--For purposes of this section, the following definitions shall apply: ``(A) Special mortgage.--The term `special mortgage' means any consumer credit transaction secured by the consumer's principal dwelling that was originated, subsidized, funded, or guaranteed by or through a State, tribal, or local government, or nonprofit organization, that bears 1 or more of the following nonstandard payment terms which substantially benefit the consumer: ``(i) Payments vary with income. ``(ii) Payments of principal or interest are not required or can be deferred under specified conditions. ``(iii) Principal or interest is forgivable under specified conditions. ``(iv) Either no interest or an annual interest rate of 2 percent or less is charged in connection with the loan. ``(B) Authorized loan counselor.--The term `authorized independent loan counselor' means any nonprofit, third-party individual or organization providing homebuyer education programs, foreclosure prevention services, mortgage loan counseling, or credit counseling that is certified by the Secretary of Housing and Urban Development, or certified by any State housing agency or nonprofit organization designated by such Secretary, for such purposes. ``(f) Minimum Financial Requirements for Mortgage Brokers.--No mortgage broker may obtain or arrange for any consumer credit transaction secured by the consumer's principal dwelling unless at all times the mortgage broker-- ``(1) maintains a minimum net worth, net of intangibles, of at least $500,000, as determined in accordance with generally accepted accounting principles; or ``(2) maintains a surety bond or irrevocable letter of credit in the amount of $50,000. ``(g) Enforcement.--For purposes of providing a cause of action for any failure by a mortgage broker to comply with any requirement imposed under this section, section 130(a) shall be applied with respect to any such failure-- ``(1) by substituting `mortgage broker' for `creditor' each place such term appears in such section; and ``(2) by treating all qualified finance charges (as defined in subsection (c)(2)(A)) incurred in the origination of any consumer credit transaction secured by the consumer's principal dwelling as actual damages sustained by the consumer as a result of the failure. ``(h) Exclusion of Reverse Mortgages.--This section shall not apply with respect to any consumer mortgage transaction that constitutes a reverse mortgage.''. (b) Technical and Conforming Amendments.--The Truth in Lending Act is amended-- (1) in section 103 (u) (15 U.S.C. 1602(u)), by striking ``and the disclosures required by section 129(a)'' and inserting ``and the provisions of section 129 and 129A''; and (2) in section 130 (15 U.S.C. 1640), by inserting ``or 129A'' after section 129 each place such term appears. (c) Clerical Amendment.--The table of sections for chapter 2 of the Truth in Lending Act is amended by inserting after the item relating to section 129 the following new item: ``129A. Originations of consumer credit transactions secured by the consumer's principal dwelling.''.

Fairness for Homeowners Act of 2007 - Amends the Truth in Lending Act to prohibit any creditor or mortgage broker from making, providing, or arranging for any consumer credit transaction secured by a consumer's principal dwelling without verifying the consumer's reasonable ability to make the scheduled payments of principal, interest (including variable interest), real estate taxes, homeowner's insurance, assessments, and mortgage insurance premiums. Prescribes criteria for determining the reasonable ability to make such payments. Prohibits steering (arranging for a lower investment grade credit transaction if the consumer qualifies for a higher investment grade transaction) and prepayment penalties for adjustable rate mortgages (ARMs) that are not jumbo mortgages. Limits financed points, finance charges, and fees to 5% of a transaction's principal, unless the transaction is ensured or guaranteed by the Secretary of Housing and Urban Development, the Secretary of Veterans Affairs, or the Farmers Home Administration. Specifies duties of agency for mortgage brokers acting to obtain or arrange for any consumer credit transaction secured by the consumer's principal dwelling. Requires creditors and mortgage brokers to obtain independent verification that a borrower seeking to refinance a special mortgage has received counseling on the transaction's advisability. Defines "special mortgage" as one that: (1) was originated, subsidized, funded, or guaranteed by or through a state, tribal, or local government, or nonprofit organization; and (2) bears one or more specified nonstandard payment terms which substantially benefit the consumer. Prescribes minimum financial requirements for mortgage brokers. Excludes reverse mortgages from coverage by this Act.

hydrodynamic simulations of galaxy formation typically model gas cooling by tabulating the cooling rate as a function of gas properties such as the density and temperature , under certain assumptions . for example , the simplest approach , as used in some of the first cosmological hydrodynamic simulations ( e.g. * ? ? ? * ) , is to assume that the gas has primordial abundances and is in collisional ionisation equilibrium ( cie ) . @xcite also included the effects of metal - line cooling , computing cooling curves in cie for a range of metallicities . another effect that can be important for gas cooling is the presence of a photoionising uv radiation field , which can change the ionisation balance and heat the gas . @xcite showed that an extragalactic uv background ( uvb ) can suppress the cooling rate in a primordial plasma , thereby inhibiting the formation of dwarf galaxies . @xcite implemented primordial radiative cooling in the presence of a uvb in cosmological hydrodynamic simulations . @xcite considered the impact that a photoionising uvb has on cooling rates in the presence of metals . they showed that photoionisation can suppress the cooling rate by up to an order of magnitude at temperatures and densities typical of the intergalactic medium ( e.g. @xmath8 , @xmath9 ) . they also showed that variations in relative abundances from their solar values can change the cooling rate by a factor of a few . @xcite tabulated the cooling rate from 11 elements separately in the presence of the redshift - dependent uvb of @xcite , and these tables have been used in several cosmological hydrodynamic simulations ( e.g. * ? ? ? * ; * ? ? ? * ; * ? ? ? * ; * ? ? ? the effects of metal cooling and uv radiation are particularly important below @xmath10 , as cooling from atomic hydrogen becomes inefficient at such temperatures . in primordial gas , the only major coolants are h@xmath2 and hd ( e.g. * ? ? ? * ; * ? ? ? * ; * ? ? ? . however , these molecules can easily be dissociated by lyman - werner radiation ( @xmath11 ) . if metals are present , efficient cooling can continue down to @xmath12 via fine - structure line emission ( e.g. * ? ? ? * ; * ? ? ? conversely , the presence of uv radiation will hinder cooling to such low temperatures , as it heats the gas via photoionisation and photoelectric heating from dust grains , the latter of which also depends on metallicity . metallicity and uv radiation therefore influence the transition from the warm ( @xmath13 ) to the cold ( @xmath14 ) gas phase . @xcite investigated the warm - to - cold transition by calculating the minimum pressure , and hence the minimum density , at which a cold phase can exist in pressure equilibrium with a warm phase , as a function of uv intensity , metallicity , dust abundance and ionisation rate from cosmic rays and extreme uv ( euv)/x - ray radiation ( see their equations 33 - 35 ) . this minimum density increases with decreasing metallicity and increasing uv intensity ( see also @xcite ) . @xcite demonstrated that the critical surface density above which a cold ism phase can form in a galactic disc increases with decreasing metallicity and increasing uv intensity ( see his equation 23 ) . he additionally showed that the formation of a cold phase can trigger gravitational instabilities , due to the lower velocity dispersion in cold gas . metallicity and uv radiation can thus affect the star forming properties of galaxies , in particular the threshold surface density below which star formation is unable to proceed . the transition from atomic to molecular hydrogen also depends on metallicity and uv radiation ( e.g. * ? ? ? * ; * ? ? ? * ; * ? ? ? * ; * ? ? ? many of the above approaches assume that the gas is in chemical ( including ionisation ) equilibrium , or in other words , that the abundances of individual ions and molecules have reached an equilibrium or steady state . however , this assumption may not be valid if the dynamical or cooling time - scale of the gas is short compared to the chemical time - scale ( e.g. * ? ? ? * ; * ? ? ? * ; * ? ? ? * ; * ? ? ? * ; * ? ? ? * ) , or if the uv radiation field is varying on time - scales shorter than the chemical time - scale ( e.g. * ? ? ? non - equilibrium chemistry has been shown to affect cooling rates in certain idealised scenarios . for example , in collisionally ionised gas that is cooling either isobarically or isochorically , the cooling rate computed self - consistently from non - equilibrium abundances is suppressed at temperatures @xmath15 compared to gas in cie ( e.g. * ? ? ? * ; * ? ? ? * ) . @xcite investigated non - equilibrium ionisation and cooling in the presence of a photoionising radiation field , and they showed that the uvb reduces the non - equilibrium effects , although the cooling rates at @xmath15 are still suppressed with respect to chemical equilibrium . @xcite showed that , at temperatures below @xmath10 , the direction of the non - equilibrium effects is reversed and the cooling rates are enhanced , due to an increase in the electron abundance compared to equilibrium . these studies considered special cases of a plasma that is cooling at constant density or pressure . @xcite compared equilibrium and non - equilibrium chemistry and cooling in high - resolution simulations of a turbulent medium , in a box @xmath16 across . they found that non - equilibrium chemistry did have a noticeable , albeit fairly small , effect on the gas temperature in their simulations . @xcite applied a treatment for non - equilibrium cooling to simulations of a supernova remnant , and showed that the evolution of the supernova remnant is sensitive to non - equilibrium effects . however , it remains to be seen whether such non - equilibrium effects will be relevant on galactic scales . in this paper we investigate the effects of metallicity , uv radiation and non - equilibrium chemistry on galaxy formation . we run a series of hydrodynamic simulations of isolated galaxies with stellar and total halo masses of @xmath17 and @xmath18 , respectively . the simulations use a resolution of @xmath1 per particle and a gravitational force softening of @xmath19 , which is sufficient to resolve the warm - to - cold transition . we consider a range of metallicities , @xmath20 , and a range of uv radiation fields that span nearly three orders of magnitude in hi photoionisation rate : the local interstellar radiation field ( isrf ) of @xcite , ten per cent of the @xcite isrf and the redshift zero extragalactic uv background ( uvb ) of @xcite . we include a local prescription for self - shielding by gas and dust , and we also consider a model without self - shielding for comparison . we first run these simulations with the temperature and chemical abundances of the gas evolved using the non - equilibrium chemical model of @xcite , which follows the ionisation states of 11 elements that are important for the gas cooling rate , along with the abundances of 20 molecular species , including h@xmath2 and co. we then compare these to simulations evolved using cooling rates tabulated in chemical equilibrium . in addition to the dynamical impact on the galaxy due to the effects on the cooling rate , non - equilibrium chemistry can also affect observable diagnostics of individual chemical species , e.g. in the presence of a fluctuating uv field @xcite , or in the presence of supersonic turbulence @xcite . to investigate how non - equilibrium chemistry can affect observable emission on galactic scales , we perform radiative transfer calculations in post - processing to compute line emission from cii and co. we then compare the intensity of line emission computed from non - equilibrium abundances to that computed assuming chemical equilibrium . the remainder of this paper is organised as follows . in section [ models_section ] we describe the hydrodynamic methods and subgrid physics models used in our simulations . we present our simulations in section [ simulations ] , where we discuss the initial conditions ( [ ic_section ] ) , morphologies and star formation rates ( [ sf_section ] ) , outflow properties ( [ outflows_section ] ) , and the phase structure of the ism ( [ phase_structure ] ) . we compute the observable line emission from cii and co in section [ line_emission ] , and we summarise our main results in section [ conclusions ] . our simulations were run using a modified version of the tree / smoothed particle hydrodynamics ( sph ) code gadget3 ( last described in * ? ? ? * ) . the hydrodynamic equations were solved using the set of numerical methods known as anarchy , which includes many of the latest improvements to the standard sph implementation . in particular , anarchy uses the pressure - entropy formulation of sph , derived by @xcite ; the artificial viscosity switch of @xcite ; a switch for artificial conduction , similar to that used in @xcite ; the time - step limiters of @xcite ; and the @xmath21 @xcite kernel . anarchy will be described in more detail in dalla vecchia ( in preparation ) ; see also appendix a of @xcite for a description of the implementation of anarchy in the cosmological simulations that were run for the eagle project , which is identical to the anarchy implementation that we use here . we use prescriptions to model physical processes that are unresolved in our simulations , including the chemical evolution of ions and molecules , radiative cooling , star formation and stellar feedback . these subgrid models are summarised below . we use the chemical model of @xcite to evolve the chemical abundances of 157 species , including all ionisation states of the 11 elements that are most important for cooling and 20 molecular species , h@xmath22 , h@xmath23 , oh , h@xmath24o , c@xmath2 , o@xmath2 , hco@xmath25 , ch , ch@xmath2 , ch@xmath23 , co , ch@xmath25 , ch@xmath22 , oh@xmath25 , h@xmath2o@xmath25 , h@xmath26o@xmath25 , co@xmath25 , hoc@xmath25 , o@xmath22 . ] . the gas temperature is evolved using radiative cooling and heating rates calculated from the non - equilibrium abundances . this gives us a set of 158 differential equations ( 157 chemical rate equations and the energy equation ) , which we integrate over each hydrodynamic timestep for each gas particle . we integrate these differential equations using the backward difference formula method and newton iteration in cvode ( from the sundials suite of non - linear differential / algebraic equation solvers ) , using a relative tolerance of @xmath27 and an absolute tolerance of @xmath28 . we summarise the main chemical and thermal processes that are included in our model below . we include collisional ionisation , radiative and di - electronic recombinations and charge transfer reactions . the formation of molecular hydrogen occurs on dust grains , using equation 18 of @xcite with a dust temperature @xmath29 , as well as via gas phase reactions . we also include cosmic ray ionisations , assuming a primary ionisation rate of atomic hydrogen due to cosmic rays of @xmath30 @xcite . the primary ionisation rates of other species due to cosmic rays are then scaled to this value using the ratios in the umist database @xcite where available , or using the equations from @xcite , @xcite and @xcite otherwise . we include secondary ionisations of hi and hei from cosmic rays using the tables of @xcite , assuming a typical mean primary electron energy of @xmath31 . .properties of the uv radiation fields considered in this paper . [ cols="<,^,^,^,^",options="header " , ] in the presence of the @xcite isrf ( ref and hiz ) , we find that the mean @xmath6 factor decreases by a factor @xmath7 when we use non - equilibrium abundances . at lower radiation field strengths ( lowisrf and uvb ) , the effect of non - equilibrium chemistry on the mean @xmath6 factor is much smaller ( e.g. @xmath32 per cent in the uvb runs ) . nevertheless , we saw in fig . [ line_noneq_fig ] that the mean co intensity for weaker radiation fields is lower , by a factor of @xmath33 , when we use non - equilibrium abundances than in equilibrium . we also find fewer pixels with @xmath34 above the detection threshold of @xmath35 when we use non - equilibrium abundances in these examples . if we find fewer pixels with detectable co emission when we use non - equilibrium abundances , we might also expect this to have an impact on the fraction of co - dark molecular gas , i.e. molecular hydrogen that is not traced by co emission ( e.g. * ? ? ? * ; * ? ? ? ? * ; * ? ? ? we calculated the co dark fraction in the simulations ref , hiz , lowisrf and uvb . this is the mass of h@xmath2 in pixels with @xmath36 divided by the mass of h@xmath2 in all pixels of the co map . for each simulation , we averaged this co dark fraction over ten snapshots taken at intervals of 100 myr . when we use h@xmath2 abundances and co maps in non - equilibrium , the co dark fraction is @xmath37 in these four simulations , with no strong dependence on metallicity or uv radiation field . however , when we set the abundances to chemical equilibrium , the co dark fraction in the uvb and lowisrf runs decreases to 0.63 and 0.59 , respectively . in the ref and hiz runs , the effect of non - equilibrium chemistry is weaker , as the co dark fraction only changes by ten per cent when we use equilibrium abundances . @xcite used theoretical models of molecular clouds to determine the co dark fraction for different cloud masses and uv radiation fields . they found an almost constant co dark fraction of 0.3 , although they only considered individual clouds , whereas we compute the co dark fraction over the disc of the galaxy , including diffuse gas . @xcite simulated four milky way - type galaxies with different gas surface densities and uv radiation fields . they found co dark fractions of @xmath38 . the highest values that they found are consistent with our simulations , although they also found that increasing the strength of the uv radiation field by a factor of 10 increases the co dark fraction by a factor of @xmath39 . we do not find any strong dependence on uv radiation field in our simulations . we have run a series of hydrodynamic simulations of isolated galaxies with a virial mass @xmath40 and stellar mass @xmath0 . the models use a resolution of @xmath1 per gas particle and a gravitational force resolution of @xmath19 , and were run with a modified version of the sph code gadget3 . we included a treatment for the full non - equilibrium chemical evolution of ions and molecules ( 157 species in total ) , along with gas cooling rates computed self - consistently from these non - equilibrium abundances @xcite , and we compared these to simulations evolved using cooling rates in chemical equilibrium . our simulations were run at a fixed metallicity and in the presence of a uniform uv radiation field , with a local prescription for self - shielding by gas and dust . we covered a wide range of metallicities ( @xmath41 , @xmath42 and @xmath43 ) , and different uv radiation fields that span nearly three orders of magnitude in hi photoionisation rate ( the @xcite isrf , ten per cent of the @xcite isrf , and the redshift zero uvb of @xcite ; see table [ uv_table ] ) , and we also repeated the runs with the @xcite uvb without self - shielding . our goal was to investigate the effects of metallicity , radiation field and non - equilibrium chemistry , which have all been demonstrated to affect gas cooling rates , in simulations of galaxy evolution . there are two aspects to the impact of these effects . firstly , how the changes in gas cooling rates affect the evolution of the galaxy , and secondly , how observable tracers of individual chemical species are affected . our main results are as follows : 1 . in simulations at higher metallicity , and for weaker uv radiation fields , gas can more easily cool to a cold ( @xmath44 ) , star forming ism phase , due to increased metal - line cooling and reduced uv heating respectively . we thus find higher star formation rates in these cases , by two orders of magnitude and a factor @xmath45 for the different metallicities and different radiation fields , respectively , that we consider here ( fig . [ sfh ] ) . in particular , the gas surface density threshold below which star formation is cut off decreases with increasing metallicity and decreasing uv radiation field ( fig . [ ks ] ) , as predicted by @xcite . we find higher mass outflow rates at higher metallicity ( by two orders of magnitude ) and for weaker radiation fields ( by a factor @xmath45 ) , due to the higher star formation rates ( fig . [ radial_outflows_fig ] ) . however , the average mass loading factor ( i.e. the ratio of outflow to star formation rates ) , measured at @xmath46 , is @xmath47 , regardless of metallicity or radiation field . 3 . the mass loading factor , @xmath48 , measured @xmath49 above and below the disc decreases with increasing gas surface density , @xmath50 , following approximately a power - law , @xmath51 ( fig . [ mass_loading_fig ] ) . at fixed @xmath50 , the mass loading factor increases with decreasing metallicity and increasing radiation field strength . 4 . non - equilibrium cooling does not strongly affect the total star formation rate of the galaxy ( fig . [ sfh ] ) . the initial rise in mass outflow rate in the first @xmath52 of the simulation is sometimes more gradual when we use equilibrium cooling , compared to the non - equilibrium runs ( fig . [ radial_outflows_fig ] ) . however , apart from this initial difference , non - equilibrium cooling does not strongly affect the outflow properties . 5 . non - equilibrium chemistry does have a large effect on the chemical make - up of outflowing gas ( fig . [ h2_outflow_fig ] ) . for example , in our reference run ( black curves in fig . [ h2_outflow_fig ] ) , we find on average @xmath53 of h@xmath2 outflowing with a vertical velocity of @xmath3 if we use non - equilibrium abundances , compared to @xmath54 if we assume chemical equilibrium . non - equilibrium chemistry therefore enhances the mass of outflowing h@xmath2 by a factor @xmath4 in this example . this has important implications for modelling molecular outflows in hydrodynamic simulations of galaxies . we investigated where in the temperature - density plane molecular hydrogen is out of equilibrium ( fig . [ noneqratio_h2_fig ] ) . h@xmath2 can be enhanced , by up to six orders of magnitude , in gas that was previously in molecular clouds at higher densities but has since been disrupted . we also find regions , around @xmath55 , where h@xmath2 is underabundant , by up to an order of magnitude . this is due to gas that is starting to form molecular clouds , but has not yet had enough time to fully form h@xmath2 . 7 . using the publicly available monte - carlo radiative transfer code radmc-3d , we performed radiative transfer calculations on our simulations in post - processing to compute the line emission from cii and co. cii emission from the @xmath56 line is stronger at higher metallicity and for stronger radiation fields ( fig . [ cii_emission_fig ] ) , while co emission from the @xmath57 line is stronger at higher metallicity and for weaker radiation fields ( fig . [ co_emission_fig ] ) . 8 . cii emission is generally unaffected by non - equilibrium chemistry , whereas co emission is affected by a factor of @xmath5 ( fig . [ line_noneq_fig ] ) . however , the co emission can be either higher or lower in non - equilibrium , since , similarly to h@xmath2 , the co abundance can be either enhanced or suppressed . this also affects the mean @xmath6 conversion factor between co line intensity and h@xmath2 column density ( equation [ co_equation ] ) that we measure in the simulations , by up to a factor @xmath7 ( table . [ xco_table ] ) . 9 . non - equilibrium chemistry also affects the fraction of co - dark molecular gas ( e.g. * ? ? ? * ; * ? ? ? * ; * ? ? ? * ; * ? ? ? * ) , i.e. the fraction of molecular hydrogen that is not traced by observable co emission . for example , in our ` lowisrf ' run , we find @xmath58 per cent of the h@xmath2 mass in the central @xmath59 of the disc lies in pixels with @xmath36 if we use non - equilibrium abundances , compared to @xmath60 per cent if we assume chemical equilibrium . to summarise , we have demonstrated that metallicity and uv radiation affect the global properties of galaxies , such as their star formation rates , and the observable signatures of individual chemical species . in contrast , non - equilibrium chemistry and cooling generally do not strongly affect the global properties of galaxies , although they do affect the observable diagnostics , particularly in molecular gas . to investigate how sensitive these results are to the resolution of the simulations , we also repeated the ref simulation twice , with a mass resolution a factor of four higher and lower than our fiducial resolution of @xmath1 . we find that our results are mostly unaffected by resolution over the range that we test here . in particular , the star formation rates ( fig . [ sfh ] ) are similar at the three different resolutions , although the low resolution run shows a smoother star formation history with no strong bursts . the mass loading factors of the outflows ( fig . [ mass_loading_fig ] ) are also similar at different resolutions . the mass of outflowing molecular hydrogen ( fig . [ h2_outflow_fig ] ) is similar at our fiducial and high resolutions , although the low resolution run shows less difference between non - equilibrium and equilibrium in the molecular outflows . however , there are several important caveats that we need to highlight that may mean that we have underestimated the importance of non - equilibrium chemistry in these simulations . firstly , we simulate isolated galaxies that do not include cosmological processes such as galaxy mergers and accretion of gas onto the galaxy . we might expect that such processes could enhance the non - equilibrium effects . for example , during and immediately after a merger , the ism will evolve rapidly as it re - distributes its gas in the temperature - density plane . this could potentially drive chemical abundances further out of equilibrium . to investigate the importance of such processes for the chemistry , we could repeat this study using cosmological zoomed simulations of individual galaxy haloes . secondly , turbulence in the ism can also drive chemical abundances out of equilibrium . for example , @xcite recently presented a series of high - resolution simulations of the turbulent ism . they showed that the steady - state ion abundances at the end of their simulations can be out of equilibrium by several orders of magnitude at high mach numbers . if , as expected , we do not fully resolve such small - scale turbulence in our simulations , then we are likely to underestimate the importance of non - equilibrium chemistry . thirdly , chemical abundances can also be driven out of equilibrium by a fluctuating radiation field . for example , @xcite demonstrated that the abundances of metal ions in the circumgalactic medium can be affected by the presence of an agn even after the agn has turned off , as it takes a long time for the ions to recombine . in our simulations , we apply a local prescription for self - shielding of the radiation field by gas and dust , which does vary with position and time . however , we apply the self - shielding to a constant , uniform radiation field . in reality , the uv radiation from young stars will fluctuate as new stars are born , existing stars age and gas particles move in relation to the stars . this may drive additional non - equilibrium effects that we do not capture in our current simulations . furthermore , since we have shown that uv radiation affects the global properties of galaxies , the inclusion of a fluctuating radiation field will also influence the galaxy directly , in addition to any non - equilibrium effects that it may drive . likewise , it will also be important to include fluctuations in metallicity due to chemical enrichment from stars , which are not included in the fixed - metallicity models that we present here . we are very grateful to volker springel for sharing gadget3 and his inital conditions code , and to claudio dalla vecchia for allowing us to use anarchy . we thank everyone who has contributed to the development of the eagle code , which our simulations were partly based on , and we thank rob crain , benjamin oppenheimer , simon glover and ewine van dishoeck for useful discussions . we gratefully acknowledge support from the european research council under the european union s seventh framework programme ( fp7/2007 - 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we present a series of hydrodynamic simulations of isolated galaxies with stellar mass of @xmath0 . the models use a resolution of @xmath1 per particle and include a treatment for the full non - equilibrium chemical evolution of ions and molecules ( 157 species in total ) , along with gas cooling rates computed self - consistently using the non - equilibrium abundances . we compare these to simulations evolved using cooling rates calculated assuming chemical ( including ionisation ) equilibrium , and we consider a wide range of metallicities and uv radiation fields , including a local prescription for self - shielding by gas and dust . we find higher star formation rates and stronger outflows at higher metallicity and for weaker radiation fields , as gas can more easily cool to a cold ( few hundred kelvin ) star forming phase under such conditions . contrary to variations in the metallicity and the radiation field , non - equilibrium chemistry generally has no strong effect on the total star formation rates or outflow properties . however , it is important for modelling molecular outflows . for example , the mass of h@xmath2 outflowing with velocities @xmath3 is enhanced by a factor @xmath4 in non - equilibrium . we also compute the observable line emission from cii and co. both are stronger at higher metallicity , while cii and co emission are higher for stronger and weaker radiation fields respectively . we find that cii is generally unaffected by non - equilibrium chemistry . however , emission from co varies by a factor of @xmath5 . this has implications for the mean @xmath6 conversion factor between co emission and h@xmath2 column density , which we find is lowered by up to a factor @xmath7 in non - equilibrium , and for the fraction of co - dark molecular gas . [ firstpage ] astrochemistry - ism : atoms - ism : molecules - galaxies : evolution - galaxies : ism .

incompressibility of nuclear matter , also knows as compressional modulus has a special interest in pure nuclear and astro - nuclear physics , because of its fundamental role in guiding the equation of state ( eos ) for nuclear matter . compressional modulus @xmath1 can not be measured by any experimental technique directly , rather it depends indirectly on the experimental measurement of isoscalar giant monopole resonance ( isgmr ) for its conformation @xcite . this fact enriches the demand of correct measurement of excitation energy of isgmr . the relativistic parameter with random phase approaches ( rpa ) constraint the range of the compressibility modulus @xmath2 mev @xcite for nuclear matter . similarly , the non - relativistic formalism with hartree - fock ( hf ) plus rpa allows the acceptable range of compressibility modulus @xmath3 mev , which is less than relativistic one . it is believed that the part of this discrepancy in the acceptable range of compressional modulus comes from the diverse behavior of the density dependence of symmetry energy in relativistic and non - relativistic formalism @xcite . now , both the relativistic and non - relativistic formalisms come with a general agreement on the value of nuclear compressibility i.e. , @xmath4 mev @xcite . but the new experiment on @xmath5 isotopic series i.e. , @xmath6 rises the question `` why tin is so fluffy ? ' ' @xcite . this question again finger towards the correct theoretical investigation of compressibility modulus . thus , it is worthy to investigate the compressibility modulus in various theoretical formalisms . most of the relativistic and non - relativistic theoretical models reproduce the strength distribution very well for medium and heavy nuclei , like @xmath7 and @xmath8 , respectively . but at the same time it overestimate the excitation energy of @xmath5 around 1 mev . this low value of excitation energy demands lower value nuclear matter compressibility . this gives a new challenge to both the theoretical and experimental nuclear physicsts . till date , lots of effort have been devoted to solve this problem like inclusion of pairing effect @xcite , mutually enhancement effect ( mem ) etc . @xcite . but the pairing effect reduces the theoretical excitation energy only by 150 kev in @xmath5 isotopic series , which may not be sufficient to overcome the puzzle . similarly , new experimental data are not in favor of mem effect@xcite . measurement on excitation energy of @xmath9 shows that the mem effect should rule out in manifestation of stiffness of the @xmath5 isotopic series . here , in the present work , we use the relativistic thomas - fermi ( rtf ) and relativistic extended thomas - fermi ( retf ) @xcite with scaling and constraint approaches in the frame - work of non - linear @xmath10 model @xcite . the retf is the @xmath11 correction to the rtf , where variation of density taken care properly mostly in the surface of the nucleus @xcite . the retf formalism is more towards the quantal hartee approximation . it is also verified that the semiclassical approximation like thomas - fermi method is very useful in calculation of collective property of nucleus , like giant monopole resonance ( gmr ) . in particular , for heavier mass nuclei , it gives almost similar results with the complicated quantal calculation . this is because of quantal correction are averaged out in heavier mass nuclei and results are inclined toward semiclassical one . so it is very much instructive to calculate excitation energy of various nucleus by this method and compared with experimental results . since , last one decade , the softness of sn isotopes remain a headache for both theorists and experimentalists , it is worthy to discuss the softness of tin isotopes in semiclassical approximations like retf and rtf . here , we calculate the excitation energy of sn isotopes from @xmath12sn to @xmath13sn using the semi - classical rtf and retf model . the different momentum ratio like @xmath14 and @xmath15 are compared with the scaling and constraint calculations . the theoretical results are computed in various parameter sets such as nl - sh , nl1 , nl2 , nl3 and fsug . we analyzed the predictive power of these parameter sets and discussed various aspects of the compressibility modulus . this paper is organized as follow : in section ii we have summarized the theoretical formalisms , which are useful for the present analysis . in section iii , we have given the discussions of our results . here , we have elaborated the giant monopole resonance obtained by various parameter sets and their connectivity with compressibility modulus . the last section is devoted to a summary and concluding remarks . the principle of scale invariance is used to obtain the virial theorem for the relativistic mean field @xcite theory by working in the relativistic thomas fermi ( rtf ) and relativistic extended thomas - fermi ( retf ) approximations @xcite . although , the scaling and constrained calculations are not new , the present technique is developed first time by patra et al @xcite , which is different from other scaling formalisms . the detail formalisms of the scaling method are given in refs . @xcite . for completeness , we have outlined briefly some of the essential expressions , which are needed for the present purpose . we have worked with the non - linear lagrangian of boguta and bodmer @xcite to include the many - body correlation arises from the non - linear terms of the @xmath16meson self - interaction @xcite for nuclear many - body system . the nuclear matter compressibility modulus @xmath1 also reduces dramatically by the introduction of these terms , which motivates to work with this non - liner lagrangian . the relativistic mean field hamiltonian for a nucleon - meson interacting system is written by @xcite : @xmath17 \varphi_i + \frac{1}{2 } \left [ ( \vec{\nabla}\phi)^2 + m_{s}^2 \phi^2 \right ] + \frac{1}{3 } b \phi^3\nonumber\\ & + & \frac{1}{4 } c \phi^4 -\frac{1}{2 } \left [ ( \vec{\nabla } v)^2 + m_{v}^2 v^2 \right]\nonumber\\ & - & \frac{1}{2 } \left [ ( \vec{\nabla } r)^2 + m_\rho^2 r^2 \right ] - \frac{1}{2 } \left(\vec{\nabla } { \cal a}\right)^2 - \frac { \zeta_0}{24 } g_{v}^4{v}^4 \\ & - & { \lambda_v } { g_v^2}{g_\rho}^2{r^2}{v^2 } \end{aligned}\ ] ] here @xmath18 , @xmath19 , @xmath20 and @xmath21 are the masses for the nucleon ( with @xmath22 being the effective mass of the nucleon ) , @xmath23 , @xmath24 and @xmath25mesons , respectively and @xmath26 is the dirac spinor . the field for the @xmath27-meson is denoted by @xmath28 , for @xmath29-meson by @xmath30 , for @xmath31-meson by @xmath32 ( @xmath33 as the @xmath34 component of the isospin ) and for photon by @xmath35 . @xmath36 , @xmath37 , @xmath38 and @xmath39=1/137 are the coupling constants for the @xmath27 , @xmath29 , @xmath31-mesons and photon respectively . @xmath40 and @xmath41 are the non - linear coupling constants for @xmath27 mesons . by using the classical variational principle we obtain the field equations for the nucleon and mesons . in semi - classical approximation , we can write the above hamiltonian in term of density as : @xmath42 where @xmath43\varphi_i,\end{aligned}\ ] ] @xmath44 @xmath45 @xmath46 and @xmath47 is the free part of the hamiltonian . the total density @xmath48 is the sum of proton @xmath49 and neutron @xmath50 densities . the semi - classical ground - state meson fields are obtained by solving the euler lagrange equations @xmath51 ( @xmath52 ) . @xmath53\ ] ] @xmath54\end{aligned}\ ] ] @xmath55\ ] ] @xmath56 the above field equations are solved self - consistently in an iterative method . @xmath57 with @xmath58 in order to study the monopole vibration of the nucleus we have scaled the baryon density @xcite . the normalized form of the baryon density is given by @xmath59 @xmath60 is the collective co - ordinate associated with the monopole vibration . as fermi momentum and density are inter - related , the scaled fermi momentum is given by @xmath61^{\frac{1}{3}}.\end{aligned}\ ] ] similarly @xmath62 , @xmath30 , @xmath32 and coulomb fields are scaled due to self - consistence eqs . ( 7 - 10 ) . but the @xmath62 field can not be scaled simply like the density and momentum , because the source term of @xmath63 field contains the @xmath62 field itself . in semi - classical formalism , the energy and density are scaled like @xmath64,\end{aligned}\ ] ] @xmath65 the symbol @xmath66 shows an implicit dependence of @xmath67 . with all these scaled variables , we can write the hamiltonian as : @xmath68 here we are interested to calculate the monopole excitation energy which is defined as @xmath69 with @xmath70 is the restoring force and @xmath71 is the mass parameter . in our calculations , @xmath72 is obtained from the double derivative of the scaled energy with respect to the scaled co - ordinate @xmath73 at @xmath74 and is defined as @xcite : @xmath75_{\lambda=1},\end{aligned}\ ] ] and the mass parameter @xmath76 of the monopole vibration can be expressed as the double derivative of the scaled energy with the collective velocity @xmath77 as @xmath78 where @xmath79 is the displacement field , which can be determined from the relation between collective velocity @xmath77 and velocity of the moving frame , @xmath80 with @xmath81 is the transition density defined as @xmath82 taking @xmath83 . then the mass parameter can be written as @xmath84 . in non - relativistic limit , @xmath85 and the scaled energy @xmath86 is @xmath87 . the expressions for @xmath88 and @xmath89 can be found in @xcite . along with the scaling calculation , the monopole vibration can also be studied with constrained approach @xcite . in this method , one has to solve the constrained functional equation : @xmath90=e(\eta)-\eta\int{dr}{r}^2\rho.\end{aligned}\ ] ] here the constrained is @xmath91 . the constrained energy @xmath92 can be expanded in a harmonic approximation as @xmath93 the second order derivative in the expansion is related with the constrained compressibility modulus for finite nucleus @xmath94 as @xmath95 and the constrained energy @xmath96 as @xmath97 in the non - relativistic approach , the constrained energy is related by the sum rule weighted @xmath98 . now the scaling and constrained excitation energies of the monopole vibration in terms of the non - relativistic sum rules will help us to calculate @xmath99 , i.e. the resonance width @xcite , @xmath100 it is interesting to apply the model to calculate the excitation energy of sn isotopic series and compared with experimental results . thus , we calculate the gmr energy using both the scaling and constraint methods in the frame - work of relativistic extended thomas - fermi approximation using various parameter sets for z= 48 and 50 and compared with the excitation energy with momentum ratio @xmath101 and @xmath102 obtained from multipule decomposition analysis ( mda ) . the basic reason to take a number of parameter sets is that the infinite nuclear matter compressibility of these forces cover a wide range of values . for example , nl - sh has compressibility 399 mev , while that of nl1 is 210 mev . from mda analysis we get different momentum ratio , such as @xmath101 , @xmath103 and @xmath102 . these ratios are connected to scaling , centroid and constraint energies , respectively . that is why we compared our theoretical scaling result with @xmath104 and @xmath105 with the constrained calculations . giant monopole excitation energy obtained by scaling method with various parameter sets are compared with experimental @xcite @xmath104 for cd and sn isotopes . ] same as fig . 1 , but for @xmath105 . ] in figures 1 and 2 we have shown the @xmath14 and @xmath15 ratio for isotopic chains of cd and sn . the results are also compared with experimental data obtained from ( rcnp ) . from the figures , it is cleared that the experimental value lies between the results obtained from fusg ( fsugold ) and nl1 force parameters . it is to be noted that , throughout the calculations , we have used only the non - linner parameter sets for their excellent prediction of nuclear observables with the experimental data . if one compares the experimental and theoretical results for @xmath106pb , the fsug set gives better results amongst all . for example , the experimental and theoretical data are [email protected] and 14.04 mev , respectively . these values are well matched with each other . from this , one could conclude that the infinite nuclear matter compressibility lies nearer to that of fsug ( 230.28 mev ) parameter . but experimental result on isgm in rcnp shows that the predictive power of fusg is not good enough for the excitation energy of sn isotopes . this observation is not only confined to rcnp formalism , but also persists in the more sophisticated rpa approach . in table i , we have given the results for qrpa(t6 ) , retf(fsug ) and retf(nl1 ) . the experimental data are also given to compare all these theoretical results . [ cols="^,^,^,^,^,^,^,^,^",options="header " , ] in table iv , we have listed the compressibility of some of the selected nuclei in scaling @xmath108 and constraint @xmath109 icalculations . this results are compared with the computed values obtained from eos model . to evaluate the compressibility from eos , we have followed the procedure discussed in @xcite . m. centelles et al @xcite , parameterised the density for finite nucleus as @xmath110 and obtained the asymmetry coefficient @xmath111 of the nucleus with mass a from the eos at this particular density . here also , we have used the same parametric from of the density and obtained the compressibility of finite nucleus from the eos . for example , @xmath112 for @xmath113 in fsug parameter set . we have calculated the compressibility from the eos at this particular density , which comes around 145 mev . we have also calculated the compressibility independently in thomas - fermi and extended thomas - fermi using scaling and constraint calculations , which are 161 mev and 146.1 mev , respectively . in summary , we analysed the predictive power of various force parameters , like nl1 , nl2 , nl3 , nl - sh and fsug in the frame - work of relativistic thomas - fermi and relativistic extended thomas - fermi approaches for giant monopole excitation energy of sn - isotopes . the calculation is then extended to some other relevant nuclei . the analysis shows that thomas - fermi approximation gives better resluts than pairing+mem data . it exactly reproduces the experimental data for sn isotopes , when the compressibility of the force parameter is within @xmath0 mev . we also concluded that a parameter set can reproduce the excitation energy of sn isotopes , if its infinite nuclear matter compressibility lies within @xmath0 mev , however , fails to reproduce the gmr data for other nuclei within the same accuracy . we have qualitatively analized the difference in gmr energies retf - rtf using retf and rtf formalisms in various force parameters . the fsugold parameter set shows different behavior from all other forces . also , extended our calculations of monopole excitation energy for sn isotopes with a force parametrization having softer symmetry energy ( nl3 + @xmath114 ) . the excitation energy decreses with the increse of proton - neutron asymetry agreeing with the experimental trend . in conclusion , after all these thorough analysis , it seems that the softening of sn isotopes is an open problem for nuclear theory and more work in this direction are needed . 99 j. p. blaizot , phys . rep . * 64 * , 171 ( 1980 ) . g. a. lalazissis , j. knig and p. ring , phys . c * 55*,540 ( 1997 ) . d. vretenar , a. wandelf and p. ring , phys . b * 487 * , 334 ( 2002 ) . c. j. horowitz and j. piekarewicz , phys . 86 * , 5647 ( 2001 ) . c. j. horowitcz and j. piekarewicz , phys . c * 64 * , 062802 ( r ) ( 2001 ) . g. colo et al . c * 70 * , 024307 ( 2004 ) . b. g. todd - rutel and j. piekarewicz , phys . lett . * 95 * , 122501 ( 2005 ) . b. k. agrawal , s. shlomo and v. kim au , phys . c * 86 * , 031304 ( 2005 ) . u. garg , arxiv : 1101.3125 t. li et al . , phys rev . lett . * 99 * , 162503 ( 2007 ) . u. garg et al . , nucl . a * 788 * , 36c ( 2007 ) . o. citaverese et al . , phys . c * 43 * , 2622 ( 1991 ) . li - gang cao , h. sagawa and g. colo , phys . c * 86 * , 054313 ( 2012 ) . jun li et al . , phys . c * 78 * , 064304 ( 2008 ) . e. khan , phys . c * 80 * , 011307(r ) ( 2009 ) . e. khan , phys . rev . c * 80 * , 057302 ( 2009 ) . d. patel et al , arxiv:1307.4487v2 [ nucl - ex ] . m. centelles , x. via , m. barranco and p. schuck , ann . ny * 221 * , 165 ( 1993 ) . m. centelles , x. vias , m. barranco , s. marcos and r. j. lombard , nucl . a * 537 * , 486 ( 1992 ) . c. speicher , e. engel and r.m dreizler , nucl . a * 562 * , 569 ( 1993 ) . m. centelles , m. del estal and x. vias , nucl . a * 635 * , 193 ( 1998 ) . m. centelles et al , phys . c * 47 * , 1091 ( 1993 ) . j. boguta and a. r. bodmer , nucl . a * 292 * , 413 ( 1977 ) . m. centelles , x. vias , m. barranco and p. schuck , nucl . a * 519 * , 73c ( 1990 ) . b. d. serot and j.d . walecka , adv . nucl . phys . * 16 * , 1 ( 1986 ) . s. k. patra , x. vias , m. centelles and m. del estal , nucl . a * 703 * , 240 ( 2002 ) ; 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within the frame - work of relativistic thomas - fermi and relativistic extended thomas - fermi approximations , we calculate the giant monopole resonance ( gmr ) excitation energies for sn and related nuclei . a large number of non - linear relativistic force parameters are used in this calculations . we find that a parameter set is capable to reproduce the experimental monopole energy of sn isotopes , when its nuclear matter compressibility lies within @xmath0 mev , however fails to reproduce the gmr energy of other related nuclei . that means , simultaneously a parameter set can not reproduce the gmr values of sn and other nuclei .

threshold values are of prime importance in providing a sound basis for public health decisions . a key issue is determining threshold or maximum exposure values for pollutants and assessing their potential health risks . environmental epidemiology could be instrumental in assessing these levels , especially since the assessment of ambient exposures involves relatively low concentrations of pollutants . this paper presents a statistical method that allows the determination of threshold values as well as the assessment of the associated risk using a retrospective , longitudinal study design with a prospective follow - up . morbidity data were analyzed using the fourier method , a time - series analysis that is based on the assumption of a high temporal resolution of the data . this method eliminates time - dependent responses like temporal inhomogeneity and pseudocorrelation . the frequency of calls for respiratory distress conditions to the regional mobile medical emergency service ( mmes ) in the city of leipzig were investigated . the entire population of leipzig served as a pool for data collection . in addition to the collection of morbidity data , air pollution measurements were taken every 30 min for the entire study period using sulfur dioxide as the regional indicator variable . this approach allowed the calculation of a dose - response curve for respiratory diseases and air pollution indices in children and adults . significantly higher morbidities were observed above a 24-hr mean value of 0.6 mg so2/m3 air for children and 0.8 mg so2/m3 for adults.(abstract truncated at 250 words)imagesfigure 1.figure 2 . afigure 2 . bfigure 2 . cfigure 2 . dfigure 3.figure 4.figure 5 .

an increased mortality from lung cancer has been reported in workers from two beryllium facilities in the usa that were in operation in the 1940s ( mancuso , 1980 ; wagoner et al . , 1980 ; ward et al . , the increased risk was restricted to workers in these two facilities who were first employed before 1960 , as workers hired after that date and workers employed in five other us facilities did not experience an excess lung cancer risk ( ward et al . , 1992 ) . several analyses have been carried out in different subsets of these workers ( sanderson et al . , 2001 ; levy et al . , , 2011a , schubauer - berigan et al.,2011b ) , as well as in a partially overlapping series of patients included in a registry of beryllium disease ( infante et al . , 1980 ; steenland and ward , 1991 ) . ( 2012 ) showed that the association between beryllium exposure and lung cancer risk depends upon the inclusion of highly exposed workers who were employed during the early technological phase in the two original us plants ( lorain and reading ) and those who were exposed to high levels of beryllium , including soluble beryllium compounds formed as intermediates within the extraction process . it is unclear whether these results reflect a small risk for lung cancer following very high exposure to soluble beryllium , result from confounding by lifestyle or occupational factors , and are relevant to workers employed in the modern commercial beryllium industry in which there is exposure only to insoluble beryllium . a limitation of the body of evidence on beryllium exposure and lung cancer is that results and conclusions are largely based on subsequent analyses of the same data set . we undertook this study to complement the information provided by the seven - plant study on the risk for lung cancer and other diseases among beryllium workers by analyzing data on workers exposed to insoluble beryllium and mostly not included in previous studies . the goal was to provide results that are directly relevant to the exposure circumstances of currently employed workers . this historical cohort mortality study includes employees who worked at four beryllium manufacturing facilities that only processed the insoluble forms of metallic beryllium , beryllium - containing alloys ( primarily copper beryllium ) and beryllium oxide . these facilities are located in three states , pennsylvania , arizona , and ohio ( table 1 ) . the cleveland facility consisted of two individual plants ( perkins and st clair ) located close to each other in cleveland , ohio . because of the proximity , both plants used the same employee forms ; hence , it is not possible to determine at which specific plant the employees worked . beryllium operations at the perkins plant included producing metal powder , vacuum hot pressing , powder consolidation , and machining . beryllium operations at the st clair plant consisted of the machine shop , which was transferred from the perkins plant in the early 1960s , and research and development . the shoemakersville plant , located in reading , pennsylvania , processes beryllium - containing alloys to produce strip , rod , and wire products . the reading plant , which was also in reading , pennsylvania , produced beryllium copper alloy . only employees hired at the reading plant after 1965 were included in the cohort , as beryllium ore refining and beryllium oxide production operations were performed at the facility before 1965 , meaning employees hired in this time period would have been exposed to both soluble and insoluble beryllium . the tucson plant , located in tucson , arizona , produces beryllium oxide ceramic products . facilities included in the study employees had to have worked for at least one day before 31 december 2009 at one of the plants to be eligible for inclusion in the cohort . the earliest date of hire ranged from 1947 to 1980 among the plants . numerous sources of data were used to enumerate the cohort , including employment records , electronic files , and payroll information . wherever possible , original employment records related to the establishment of the cohort were reviewed to ensure that the abstraction and computerization of the data were error free . consistency checks were also performed on the database before updating the cohort . any errors and omissions that were identified hire date was considered date of hire at any one of the plants , and person - years began to accumulate one day after hire . when termination dates were missing , the termination date was considered the earlier of either the last date the plant was operational , the end of the study , or the date of death . missing hire dates ( n=2 ) were assumed to be the date of the first known job . for employees with no detailed work history information ( n=35 ) , hire date thirty employees missing multiple data fields essential for the analysis ( which could not be assumed as outlined above ) were excluded from the analyses . employees who worked in more than one of the facilities were included once in the analyses for all plants combined for their entire duration of employment , whereas they were included in individual plant analyses for the length of employment at that particular plant . vital status was ascertained through 31 december 2009 using data from the national center for health statistics national death index ( ndi ) . the ndi is considered a complete and accurate source of mortality information on us citizens whose deaths have occurred after 1 january 1979 . cause of death information coding for individuals identified in the ndi database was obtained through ndi plus . employees not identified in the ndi databases who were still working after 1979 were presumed to still be alive as of the end of study date . vital status before 1979 was ascertained through social security administration ( ssa ) . for suspected and known deaths that occurred before 1979 , information on the state of death was obtained from the ssa and death certificates were requested from the appropriate states . a copy of the verified death certificates was sent to a professional nosologist for coding to the international classification of diseases ( icd ) revision in effect at the time of death . employees who were not located through ndi or the ssa , or who had no other vital status information available in the company records ( n=221 ) were considered lost to follow - up as of their date of termination of employment . mortality analyses were based on cause - specific standardized mortality ratios ( smrs ) , which were calculated by dividing the number of observed deaths by the number of deaths that were expected to occur . mortality in the usa was used as a reference in the analyses examining all plants combined . for plant - specific analyses , appropriate regional mortality rates were selected as references after examining demographic and socioeconomic characteristics of comparable areas surrounding the plants ( i.e. the county where the plant was located and similar neighboring counties ) . the mortality experience of the cohort was examined for all plants combined , by sex and by individual manufacturing facility , and smrs and their 95% confidence intervals ( cis ) were calculated after adjustment for age , sex , race , and calendar period using the university of pittsburgh s ocmap program . because the results of some of the previous studies on beryllium workers employed before 1960 have suggested an association between beryllium exposure and lung cancer , this constituted the primary outcome of interest . both observed deaths and person - years of workers with unknown race ( n=2292 ) were proportionally allocated on the basis of the proportion of employees in the cohort with known white race ( marsh et al . , 1998 ) . membership in the cohort was used as a surrogate measure of potential occupational exposures . as detailed work history information was not available for 30% of the cohort , we were unable to use job type as a surrogate for level of exposure . however , analyses by length of employment served as an indirect measure of exposure in the absence of exposure - monitoring data . continuous employment was assumed , although sensitivity analyses were also carried out to account for workers with breaks in their employment history and to examine the effect of these gaps in exposure on the results . analyses were also carried out to examine mortality from interval since hire as a surrogate for latency to permit examination of disease ( mortality ) to elapsed time since there were 4950 employees in the four beryllium facilities with insoluble operations ( table 1 ) . the largest facility , cleveland , contributed 45% of the cohort and the smallest facility , shoemakersville , contributed 14% of the cohort ( table 1 ) . overall , 3912 ( 79.8% ) men and 1038 ( 21.2% ) women were included in the cohort . of the total person - years of observation ( 143 670 ) , 76.0% ( 109 201 ) were contributed by white men . a total of 1480 deaths from all causes occurred over the study period ( table 2 ) . the smrs using us rates as a comparison were slightly , but not appreciably , lower than the smrs using combined county rates . the results obtained using us data as the comparison are reported in supplementary table b. standardized mortality ratios and 95% confidence intervals , total cohort the smr for all causes was significantly reduced ( smr=94.7 ; 95% ci 89.9 , 99.7 ) , largely because of the reduced smrs for two large categories of death , heart disease ( n=481 ; smr=95.0 ; 95% ci 86.7 , 103.9 ) and external causes of death ( n=99 ; smr=81.4 ; 95% ci 66.1 , 99.1 ) . observed and expected numbers of deaths from all cancers were essentially the same ( smr=99.8 ) . the observed number of deaths from lung cancer was less than expected ( n=126 ; smr=96.0 ; 95% ci 80.0 , 114.3 ) . deaths from nonmalignant respiratory disease ( n=120 ; smr=89.6 ; 95% ci 74.3 , 107.2 ) were also lower than expected . uterine cancer among women was the only cause of death with a significantly increased smr ( n=7 ; smr=302.3 ; 95% ci 121.5 , 622.9 ) . five of the seven women who died from uterine cancer worked in office jobs : three worked for less than 1 year and three worked for between 1 and 3 years . the results for men were similar to the overall results ( supplementary tables a and c ) . there was no noteworthy trend by number of years of employment for any specific cause of death ( table 3 ) . among workers with 20 or more years of employment , the smr for lung cancer was 112.7 ( 95% ci 66.8 , 178.1 ) , on the basis of 18 deaths , and that for nonmalignant respiratory diseases was 136.8 ( n=22 ; 95% ci 85.7 , 207.1 ) . a test for trend was not statistically significant for either cause of death ( p - values=0.40 and 0.07 , respectively ) . there was no significantly increased smr for any specific cause of death among the longest term employees . standardized mortality ratios and 95% confidence intervals by duration of employment , total cohort for the longest category of time from hire ( hereafter referred to as latency ) , the smrs for lung cancer and other nonmalignant respiratory diseases were not significantly increased , although there was an increase in smr with increasing latency ( table 4 ) . a test for trend was not statistically significant for either cause of death ( p - values=0.24 and 0.33 , respectively ) . standardized mortality ratios and 95% confidence intervals by latency , total cohort an analysis of the stratified data on employment start date before or after 1960 did not alter the conclusions ( data not shown ) . the smrs were generally slightly lower in the post-1960 period . in the post-1960 period , the smr for all causes of death was significantly reduced ( 89.3 ) largely because of the reduced smr for heart disease ( 90.0 ) and external causes of death ( 91.6 ) . for lung cancer , the smrs were 102.9 ( 95% ci 80.2 , 130.0 , 70 deaths ) for the pre-1960 start date period and 89.8 ( 95% ci 67.8 , 116.6 , 56 deaths ) for the post-1960 start date period . when the data were analyzed by start date ( pre-1960 and post-1960 ) and latency , the results showed that the increase in smr with increasing latency was confined to the pre-1960 start dates for lung cancer , although the trend and the smr for the longest latency period were not statistically significant ( tables 5 and 6 ) . there was no increasing trend for nonmalignant respiratory diseases during the three latency periods for either the pre-1960 or post-1960 start dates . the results for men only were essentially the same ( supplementary tables f and g ) . standardized mortality ratios and 95% confidence intervals by period of hire and latency , employees hired before 1960 , total cohort standardized mortality ratios and 95% confidence intervals by period of hire and latency , employees hired in 1960 or later , total cohort the results of this study do not support the hypothesis that exposure to insoluble beryllium causes an increased risk for lung cancer of the order of 20% or higher . they are consistent with a recent review that concluded that the increased mortality from lung cancer reported among workers employed in the early technological phase in two beryllium plants is not confirmed in studies on workers employed later on ( boffetta et al . , 2012 ) . workers in these two plants were involved in the extraction of beryllium , which entails the formation of soluble beryllium compounds as intermediates . soluble forms of beryllium are not used commercially ; only insoluble metallic products and beryllium oxide are in commerce . whether the excess lung cancer mortality among workers employed in the early technological period of the industry can be attributed to exposure to beryllium ( and specifically soluble beryllium ) or to other factors remains undetermined . in contrast , the lack of increased lung cancer risk among workers employed in the modern beryllium industry , with exposure restricted to insoluble beryllium , is supported by the results of this study . as beryllium workers are currently exposed to beryllium in the form of relatively insoluble particles such as beryllium compounds ( e.g. beryllium oxide ) or metal , our study was restricted to workers exposed to this group of agents . our results are consistent with the data on carcinogenicity of insoluble beryllium in experimental animals , which point toward a mechanism of lung overload in rats that is not relevant to humans ( strupp , 2011 ) . the only cause of death for which there was a statistically significantly increased mortality was cancer of the uterus , on the basis of seven observed deaths . cancers originating from the two parts of the uterus ( cervix , n=2 , and corpus , n=5 ) have very different epidemiological , molecular , and clinical characteristics and no overlap in known risk factors ( cook et al . , 2006 ; schiffman and hildesheim , 2006 ) . the most likely explanation for this finding , therefore , remains chance because of multiple comparisons . the analysis of mortality from non - neoplastic causes did not reveal any increased risk in this cohort . a small , nonsignificant excess of mortality from non - neoplastic respiratory diseases was observed among workers with 20 years or more of employment or 30 years of latency , which was due to non - neoplastic diseases other than chronic bronchitis and emphysema , a category that includes deaths from chronic beryllium disease ( cbd ) . in particular , cbd ( icd-8 code 516.0 , icd-9 code 503 , or icd-10 code j632 ) was the underlying cause of death of 12 cohort members . they were part of a group of 52 cohort members , whose cause of death was classified as other nonmalignant disease of the respiratory system. we were able to obtain the death certificate for 21 of these 52 deceased cohort members , including four with cbd as the underlying cause . a reference to beryllium or beryllium disease was present on an additional two certificates , which had a different underlying cause ( 2/17 , or 12% ) . if the 21 certificates were a representative sample , and cbd - related deaths were not included in other icd categories , between 12 and 17 [ 12 + 12% of ( 5212 ) ] deaths in this cohort were due to cbd . although no definitive conclusions can be drawn from these results and a longer follow - up of this cohort is needed for more conclusive evidence , the fact that we identified deaths from cbd supports the notion that these workers were indeed exposed to beryllium , and the lack of increased risk for lung cancer is not due to lack of opportunity of exposure . further , these results argue against the hypothesis of common mechanistic pathways ( e.g. beryllium - induced inflammation ) for cbd and lung cancer ( sawyer et al . , 2005 ) . the main strengths of this study lie in its prospective design , the completeness of the enumeration of the cohort , and the high success rate in follow - up . although a small risk for lung cancer is compatible with our results , we can confidently exclude an excess greater than 20% . limitations include the lack of information on job titles and quantitative exposure to beryllium ; the lack of information on jobs outside the beryllium industry ( 72% of cohort members were employed for less than 5 years ) ; and the lack of information on nonoccupational cancer risk factors , mainly tobacco smoking , although the lack of excess mortality from other tobacco - related causes argues against a strong confounding effect . the effect of factors other than employment in the beryllium industry was partially offset by the use of regional mortality rates as a reference . the lack of excess in causes associated with other occupational exposures and lifestyle factors , such as tobacco smoking , alcohol drinking , and obesity , argues against an important role of residual confounding . this study on beryllium workers employed at four facilities and exposed to insoluble beryllium does not provide evidence of an increased risk of lung cancer or any other neoplastic or non - neoplastic disease . the results support the conclusions of previous reviews that the increased mortality from lung cancer identified among workers employed in the early technological phase of the industry with high exposure to soluble beryllium is not relevant to the risk among workers employed in this industry under this study on beryllium workers employed at four facilities and exposed to insoluble beryllium does not provide evidence of an increased risk of lung cancer or any other neoplastic or non - neoplastic disease . the results support the conclusions of previous reviews that the increased mortality from lung cancer identified among workers employed in the early technological phase of the industry with high exposure to soluble beryllium is not relevant to the risk among workers employed in this industry under was not involved in the design , collection , management , analysis , or interpretation of the data , or in the preparation or approval of the manuscript . mention of trade names or commercial products does not constitute endorsement or recommendation for use . the findings and conclusions in this manuscript are those of the authors and do not necessarily represent the views of materion brush inc . pb and jm previously published a review on beryllium and cancer that was supported by an unrestricted grant from materion brush , inc .

this study investigated lung cancer and other diseases related to insoluble beryllium compounds . a cohort of 4950 workers from four us insoluble beryllium manufacturing facilities were followed through 2009 . expected deaths were calculated using local and national rates . on the basis of local rates , all - cause mortality was significantly reduced . mortality from lung cancer ( standardized mortality ratio 96.0 ; 95% confidence interval 80.0 , 114.3 ) and from nonmalignant respiratory diseases was also reduced . there were no significant trends for either cause of death according to duration of employment or time since first employment . uterine cancer among women was the only cause of death with a significantly increased standardized mortality ratio . five of the seven women worked in office jobs . this study confirmed the lack of an increase in mortality from lung cancer and nonmalignant respiratory diseases related to insoluble beryllium compounds .

NBC Bay Area has learned that authorities investigating the deadly Camp Fire have tied its origin to the failure of a single steel hook that held up a high voltage line on a nearly 100-year-old high voltage transmission tower. Investigative reporter Jaxon Van Derbeken reports. (Published Wednesday, Dec. 5, 2018) NBC Bay Area has learned that authorities investigating the deadly Camp Fire have tied its origin to the failure of a single steel hook that held up a high voltage line on a nearly 100-year-old PG&E transmission tower. The fire began at the base of a transposition tower, which serves to redistribute the electricity on the system to balance the load and assure safety. The tower has two arms holding out the “jumper,” a part of the line that’s being shifted to another point at the top of the tower. The arms each hold electrical insulators, which resemble a series of white discs. Authorities believe the fire started with the fracturing of a steel hook that holds up the insulators to the arms above. It is one of those hooks, sources with knowledge of the investigation say, that failed in high winds the morning of Nov. 8. “PG&E failed to maintain the tower, and they have an obligation to do that -- and it means they are liable for this disaster,’’ said attorney Dario de Ghetaldi, who is suing the utility over the fire. Cal Fire would not comment for this story, citing the ongoing investigation. PG&E would not address our information on the apparent cause, instead sending us a statement saying, “The cause of the Camp Fire is still under investigation. We continue to focus on assessing infrastructure, safely restoring power where possible and helping our customers recover and rebuild.” But Frank Pitre, another attorney who has sued over both wildfires and the San Bruno gas explosion, worries the hook failure is just more evidence that PG&E is simply not able to deal with the risk posed by its system. “That’s a red flag,” he said, a warning that parts of the system could fail due to corrosion and fatigue from decades of service. “You have to a have a rigorous system of inspection, particularly when you have systems that are 50 years old or more. You can’t just visually inspect these things.’’ De Ghetaldi says PG&E should have done those detailed inspections after 2012, when five towers collapsed during a winter wind storm. “They should have taken a serious look at the entire circuit,” he said, “after those five towers collapsed in 2012, and it appears they didn’t do that. That’s a big problem for PG&E. And it’s a big problem for the people who were killed, who were made homeless, and who were harmed in many ways.” ||||| The Camp Fire has produced an online interactive evacuation map for citizens to view. Click to see the MAP The Camp Fire has produced an online public viewer structure map. Click to see the MAP For the most recent up-to-date Evacuation Locations and Status go to: Butte County Website

– The cause of California's deadly Camp Fire still has not been officially released, but sources say a single hook may be the culprit. Specifically, a steel hook that held up a high voltage line on a Pacific Gas & Electric transmission tower, sources tell NBC Bay Area. There had already been much speculation that PG&E, the state's largest utility, is to blame for the wildfire that burned through more than 153,000 acres, destroying the entire town of Paradise and killing at least 85. One of the company's power lines was reportedly causing sparks just before the fire started Nov. 8, and multiple lawsuits have been filed against the utility by fire victims. Now, sources say, investigators have determined a hook on a nearly century-old PG&E transposition tower failed in high winds the morning the fire started—and it started at the base of that tower. Neither Cal Fire nor PG&E would comment on NBC's story, but an attorney representing fire victims alleges PG&E failed to properly maintain its equipment, and another attorney suggests the utility may have more problems in store if it can't keep its aging equipment safe. See the NBC report for more, including video showing wires dangling where the hook failed on the tower. (Was the president right about California wildfires?)

the discovery of the double pulsar system psr j07373039 @xcite has led to important advances in the study of radio pulsars and their associated phenomenology . the independent determination of the orbit of both neutron stars , and the recent measurement of five post - keplerian parameters from the timing of a @xcite and a sixth one from eclipse observations of a @xcite has made this the most over - constrained system known , allowing five tests of general relativity . psr j0737@xmath03039b ( henceforth b ) has many unique features . it emits pulsed radio waves during most of the orbit , but it becomes much brighter at two distinct orbital phases @xcite . furthermore , its pulse profile changes strongly with orbital phase and with time @xcite . though instructive in other ways , this behaviour has made it difficult to measure times of arrival accurately and obtain a precise estimate of the semi - major axis of the orbit of b , limiting the precision of our knowledge of the pulsar mass ratio @xmath1 and the precision of some of the tests of general relativity in this system ( see , e.g. , kramer & stairs 2008 for a recent review ) . this paper is motivated by another unique feature of b : for certain orbital phases its radio emission is clearly modulated by electromagnetic emission from a @xcite ; the phenomenon superficially resembles drifting sub - pulses ( e.g. lorimer & kramer 2005 ) . in this work , we discuss the _ timing _ of this phenomenon . in [ sec : delays ] , we present a theoretical calculation of the delay in the arrival at the earth of the sub - pulses of b relative to the radio pulses of a responsible for the drift . we name this simply the `` response delay '' . in [ sec : comparison ] , we discuss how we can compare the predicted and measured response delays . in [ sec : discussion ] , we highlight the astrophysical knowledge that can be gained from the timing of the response delays . ( 0,5.0 ) ( -3.0,0.0 ) the time between the emission of a s radio pulse and b s response can be divided in three parts , which we discuss below . 1 . the sub - pulses of b are spaced by 22.7 ms , which is the same as the spin period of a @xcite . therefore , we can think of the maximum intensity of the sub - pulses of b ( the `` response '' ) as being caused by the impact upon b s radio emitting region of a co - rotating beam of electromagnetic radiation from a. we henceforth refer to this as the em beam . since the em beam is not necessarily aligned in rotational phase with a s radio beam , as shown in fig . [ fig : rotation ] , we introduce a phase offset @xmath2 between the two beams . we define a s zero longitude to be the point where the radio emission towards the earth reaches maximum intensity . as we show later , one of the applications of our model would be the direct determination of @xmath2 . + one of the simplifying assumptions in fig . [ fig : rotation ] is that the spin axis of a is perpendicular to the orbital plane . this has been suggested @xcite as the most plausible explanation for the lack of change in the pulse profile of a ; ferdman ( 2008 ) set an upper limit of about @xmath3 for the misalignment between the orbital angular momentum and the spin of a. we henceforth assume that the spin axis of a is indeed perpendicular to the orbital plane . it is not know whether a rotates in the same sense as the orbit or in the opposite sense , but kinematic considerations @xcite make the former more likely . we discuss this issue further in [ sec : comparison ] and [ sec : discussion ] . + in fig . [ fig : rotation ] , at time @xmath4 we see a s radio beam pointing at the earth , causing the radio emission to reach a maximum . at time @xmath5 the em beam is pointing at a direction @xmath6 , where it emits the signal that will later cause b s response computed for the emission - reception - earth triangle , while uppercase subscripts refer to lambda computed for a line through the centre of mass of the binary system , o. here we have neglected aberration effects and the small angle between ab and ae , as the corresponding time delays are below the accuracy relevant for this paper . ] . between the two events a has rotated by an angle @xmath7 where @xmath8 is the longitude of a as seen from the location and time where the em signal modulated the radio pulse of b ( point e at time @xmath9 , see fig . [ fig : rotation ] ) . the positive sign corresponds to a clockwise rotation of a as shown in fig . [ fig : rotation ] , i.e. , in the same sense of the orbit . the time between the two events is given by @xmath10 where @xmath11 is the spin period of a. 2 . after @xmath5 the em pulse of a travels towards b ; at time @xmath12 it gets to b s exact position . the distance between these two events is @xmath13 , this is calculated in [ sec : distance ] . in the assumption above ( that signal travels at the speed of light ) we have @xmath14 3 . what happens near b is less certain . the simplest assumption is that the em signal is able to travel through b s magnetosphere at the speed of light ( this is possible e.g. if the em signal consists of high - energy photons ) and modulates b s earth - bound radio emission at the point where it is being generated ; we designate this as `` e '' . + we must keep in mind that this simplified assumption is not the only possible case : a ) the modulation could occur after b s radio signal is produced , i.e. , somewhere between point e and the earth and b ) more generally , the chain of events from the emission of the em signal at a ( @xmath15 ) to the modulation of the radio signal of b ( @xmath9 ) might not lie along a single null geodesic . for the time being , we will quantify the simplest case only ( see fig . [ fig : rotation ] ) . + since e is where the earth - bound radio emission is being generated , we assume it is the point of the radio - emitting region of b s magnetosphere that is in the line of sight from b to earth . this only happens when b s radio pulse is `` on '' . for most of b s rotational cycle , when its pulse is `` off '' , no part of its radio - emitting region is pointing at earth , and no response is detected . + in our simplified model , we assume that the distance of e to b is a constant @xmath16 as a function of b s spin phase . therefore , in the reference frame of the orbital plane ( with axes along the line of nodes , perpendicular to the line of nodes and perpendicular to the orbital plane ) , e is located at fixed coordinates ( 0 , @xmath17 , @xmath18 ) relative to b , where @xmath19 is the orbital inclination of the system ( see fig . [ fig : rotation ] ) . + at @xmath12 , the em wavefront from a reaches b. a small amount of time later , at @xmath9 , the same wavefront reaches e and produces the response . from that figure , we can see that @xmath20 between @xmath12 and @xmath9 the orbital motion of b will make e move by a small amount relative to the center of the binary , this will affect the arrival time at e. we note , however , that for slow pulsars @xmath21 is expected to be of the order of 1 ms @xcite . assuming this is true , a detailed calculation of the @xmath22 doppler correction due to b s ( and e s ) motion shows that this term is smaller than @xmath23 . since the r.m.s . timing precision of a is about @xmath24 , and the timing precision for b s response is likely to be worse , we will ignore all terms with magnitude @xmath25 . for the total time difference we obtain : @xmath26 which should be valid in any inertial reference frame using the orbital parameters as measured in that frame . ( 0,6 ) ( -2.4,0.0 ) we now calculate the delay between the reception at the ssb of a s radio pulses and b s responses , @xmath27 . to do this , we will start by adding to @xmath28 the difference in the ranges at which these events occur , @xmath29 divided by @xmath30 ; this is the so - called `` rmer delay '' . as in the case of @xmath28 ( eq . [ eq : time ] ) , @xmath29 can also be described as the sum of three terms , @xmath31 : 1 . the difference in range between the events at @xmath4 and @xmath5 is given by : @xmath32 where @xmath33 is the velocity of a relative to the centre of mass , projected along the line of sight to earth ( [ sec : distance ] ) . 2 . in the lower diagram of fig . [ fig : travel_time ] , we see that the difference in range between the events happening at @xmath12 and @xmath5 is given by : @xmath34 3 . ignoring the motion of e between @xmath12 and @xmath9 , we have @xmath35 the delay is therefore given by : @xmath36 where the subscript `` r '' indicates that we are taking into account the rmer delay only . in this equation we use @xmath37 to represent the spin period of a with the classical doppler correction due to its orbital velocity . this equation is valid at the ssb if we use the orbital parameters as measured there . in appendix a we present a detailed calculation of the relativistic contribution to the total response delay @xmath38 , known as the `` shapiro delay '' ( @xmath39 ) . for the range of orbital phases where we observe b s responses @xmath39 changes @xmath40 , i.e. , smaller than the r.m.s . timing precision of a. we can therefore assume @xmath41 for the remainder of this paper . ( 0,4 ) ( -2.5,0.0 ) having calculated the response delay as a function of @xmath42 and the separation between the two pulsars , @xmath13 , we now calculate these two quantities as a function of @xmath43 at @xmath5 . the reason for this is that @xmath43 can be calculated precisely for any given time using the equations in damour & deruelle ( 1985,1986 ) , furthermore , this quantity determines the instantaneous configuration of the system . in the equations that follow , we will only use the newtonian terms to @xmath44 . a detailed calculation shows that the @xmath45 newtonian terms are much smaller than the r.m.s . timing precision of a. this means that they can be ignored for or present purposes . at @xmath5 , the separation of pulsar i ( a or b ) from the centre of mass is given ( see , e.g. , roy 1988 ) by @xmath46 where @xmath47 is the semi - major axis of its orbit , @xmath48 is the orbital eccentricity and the angle @xmath49 is the true anomaly of the system at @xmath5 ( @xmath50 , where @xmath51 is the longitude of periastron of pulsar i at @xmath5 ) . the components of a pulsar s velocity along the radial ( i.e. , away from the centre of mass ) and transverse directions are given @xcite by @xmath52 where @xmath53 is the transverse velocity of pulsar i at quadrature ( @xmath54 ) and @xmath55 is the orbital period of the binary . the velocity of that pulsar relative to earth is given by ( e.g. , green 1985 ) : @xmath56 calculating this velocity for a we can immediately quantify the doppler correction term for @xmath11 in eq . [ eq : basic ] . to calculate the instantaneous distance between the pulsars ( @xmath57 ) , we replace @xmath47 by @xmath58 in eq . [ eq : delay_0 ] . during the time it takes a s signal to cross this distance ( @xmath59 ) , b is moving . because the em signal is moving in the radial direction , only the radial component of b s motion ( @xmath60 ) will affect the travel time between the two pulsars . during the cross time @xmath61 , i.e. , the distance between the events at @xmath5 and @xmath12 is @xmath62 the perpendicular motion of b between @xmath5 and @xmath12 is @xmath63 looking at fig . [ fig : blowup ] we can see that @xmath64 in the derivation above we made the approximation that @xmath42 is the longitude of a as seen from b at @xmath12 . the longitude of a as seen from point e at @xmath9 is larger by a very small amount , @xmath65 . noting that @xmath66 , @xmath67 with this result we can re - write eq . [ eq : basic ] as a function of @xmath43 : @xmath68 using eqs . [ eq : delay_0 ] , [ eq : dr ] and [ eq : r_perp ] , we can re - write this as a function of a keplerian term , @xmath69 , which can be calculated from known orbital parameters and the system s geometry , and the unknown quantities @xmath16 and @xmath70 : @xmath71 + \mathit{o } \left ( c^{-3 } \right ) . \label{eq : k}\end{aligned}\ ] ] the @xmath69 term is the time difference , measured at the ssb , between the events that occurred at @xmath12 and @xmath5 in the reference frame of the binary ; it is by far the largest contribution to the response delay . so far , we have just made a theoretical calculation of the response delays , @xmath72 . we now discuss what we can learn from actually measuring such delays . if we measure @xmath72 for several @xmath43 in a single orbit and subtract @xmath69 , we can measure the delays that are not _ a priori _ predictable : @xmath73 in order to measure @xmath72 , we have to specify a particular radio pulse of a ( in principle the closest to the time of emission of the em signal that caused that particular response ) and subtract its ( barycentric ) time from the response s barycentric time . however , because we have no prior knowledge of the terms in eq . [ eq : remains ] , there is some ambiguity in the choice of the pulse that is closest to that time of emission . an experimental method that does away with the issue of the choice of a pulse of a and even the measurement of @xmath74 entirely would proceed along the following lines : 1 . b s responses are particularly noticeable in an intensity gray - scale plot of time versus spin phase of b as presented by @xcite . in such a plot , we can determine the precise spin phase corresponding to each response ; the precise method to accomplish this and the attainable precision will be discussed elsewhere . 2 . in the next step , we convert this phase into a barycentric time . this can be achieved using the software package tempo . the result corresponds to an event that occurred at @xmath9 in the reference frame of the binary . 3 . subtracting @xmath69 , we obtain a second barycentric time that nearly corresponds to a s emission of the em pulse ( @xmath75 in the reference frame of the binary ) . at this time we calculate @xmath43 from the binary s ephemeris . 4 . subtract the nearest time at which the rotational phase of a is zero . this time should be the equivalent of @xmath76 . by fitting this to eq . [ eq : remains ] we should be able to determine @xmath16 , @xmath2 and the direction of the spin of a. with data from different orbits , we can also get a sense for the stability of @xmath2 and @xmath16 . thus far we have assumed that @xmath16 ( the height above b where the response is produced ) is a constant as a function of b s rotational phase . it is possible , however , that @xmath16 varies with b s spin phase . this would also introduce a secular variation of the @xmath16 observed for any spin phase of b due to the pulsar s geodetic precession . if that is the case , we could map the height of e above b as a function of the precession phase . confusion with @xmath69 can be avoided because , despite the fact that both terms vary with @xmath77 , only the latter varies with @xmath78 . the response delays @xmath72 will vary in time for any given @xmath43 because of the apsidal motion @xmath79 changes @xmath49 , which causes a change in @xmath69 : @xmath80,\ ] ] where @xmath9 and @xmath81 are two epochs at which the longitude @xmath43 occurs and @xmath82 other terms of order larger than @xmath83 cancel out in the subtraction because of the constant @xmath42 , and the same happens for the terms dependent on @xmath70 and @xmath16 is not correct , i.e. , it only requires that any terms dependent on @xmath16 vary with @xmath42 in a repeatable way . ] . the variation of the doppler correction to @xmath11 are @xmath84s and can therefore be ignored . the @xmath85 are important because , being due solely to a variation of @xmath69 , they are proportional to @xmath86 . the maximum variation occurs between the time when @xmath43 coincides with periastron ( @xmath87 , occurring at @xmath88 ) and apastron ( @xmath89 , occurring at @xmath90 , which for psr j0737@xmath03039 is about 10.65 years later ) : @xmath91 in a single 2003 observation , mclaughlin et al . ( 2004 ) observe b s responses from @xmath92 , i.e. , occurring shortly before the magnetosphere of b eclipses a at @xmath93 . this corresponds to @xmath94 . at these extremes we have @xmath95 and @xmath96 . the uncertainty in this prediction is entirely due to the uncertainty of @xmath86 ( which results entirely from the uncertainty in the measurement of @xmath97 ) ; it represents 0.5 1.5% of a rotation of a ; this means that we should be able to keep track of the response delays with very high confidence . the variations themselves are certainly measurable , since they are equivalent to many rotations of a. this means that we can always make an independent measurement of @xmath86 . depending on the precision and number of measurements of @xmath72 , the value of @xmath86 derived in this fashion might be more precise than the present value derived from timing . in that case , we can improve our knowledge of the mass ratio : @xmath98 where @xmath99 is the projected semi - major axis of a s orbit , in light seconds ; this quantity is directly and very precisely measured from the timing of a. this equation ( and also eqs . [ eq : delta_1 ] and [ eq : delta_2 ] ) show that , to determine @xmath100 from @xmath86 and @xmath99 we need to know @xmath101 . we could in principle determine @xmath101 independently from comparing measurements of @xmath85 made at different orbital longitudes . however , most theories of gravitation predict the shapiro `` s '' term to be the same as @xmath101 @xcite ; therefore such an independent determination is not likely to be a useful test of gravitation . for this reason , we can use the extremely precise estimate of @xmath101 from @xmath102 in the estimate of @xmath100 . finally , we remark that there is a small difference between the intrinsic and observed semi - major axes of the pulsar s orbits that is caused by aberration effects . kramer et al . ( 2006 ) estimate that for a these are of the order of @xmath103 , i.e. , about @xmath23 ; this is similar to the level of precision for the measurement of @xmath99 . it is highly unlikely that we will measure @xmath86 to a similar precision , so this should not be a problem for the determination of @xmath100 in eq . [ eq : mass_ratio ] . for b , kramer et al . estimate that the effect of aberration should be of the order of @xmath104 . it might be possible that we measure @xmath105 to better than the necessary level of precision . however , to be able to measure the aberration directly , we must be able to measure @xmath106 from timing with this level of accuracy , so that the difference between the two values becomes evident . the intrinsic uncertainty of the @xmath106 obtained from timing is about @xmath107 @xcite , one order of magnitude larger than the effect of aberration . therefore , unless the direct timing of b improves by more than one order of magnitude , the effects of aberration wo nt be separately measurable . in this paper we have calculated the delay between the radio pulses of a and the modulated radio pulses of b , @xmath72 , assuming a simple scenario for that modulation , i.e. , that it happens at the point , e , where the radio emission of b is being produced and that the modulating signal is traveling from a to e at the speed of light . things could be more complicated , particularly considering that this trajectory must intersect the magnetosphere of b. we will present details of the measurements of @xmath72 and their timing analysis elsewhere . if the response delays obey the equations presented above in a consistent manner , that will validate our model . in that case , the measurement of these delays relative to the radio pulses of a can provide us with new astrophysical information . first , a determination of the sense of a s rotation relative to its orbit , something never achieved for any other pulsar , would introduce fundamental constraints on binary evolution scenarios for this pulsar , as well as improved constraints on b s supernova kick . finding that the orbital angular momentum is anti - aligned with a s angular momentum would require a very large supernova kick @xcite . previous studies ( e.g. , willems et al . 2006 , stairs et al . 2006 ) predict instead that the kick that produced b was rather small , therefore the angular momenta should be aligned . a confirmation of this alignment , combined with the small angle between the momenta , would introduce stringent constraints on the magnitude of the kick . furthermore , we would know the sign of the expected relativistic spin - orbit contribution to @xmath79 @xcite . it is probable that this contribution will be measured in the near future @xcite ; that would allow an estimate of a s moment of inertia . the moment of inertia of a , together with the well - determined mass of the pulsar , will introduce fundamental constraints on the equation of state for dense matter @xcite . second , by measuring @xmath16 , or by introducing upper limits to it , we might be able to locate the region where the em signal from a is modulating the radio signal from b and relate it to the region where we expect the radio emission of b is being generated . thus far , the best location of pulsar radio emission comes from the interpretation of multi - frequency polarimetric pulse profiles in light of a relativistic version of the the familiar rotating vector model @xcite ; the results indicate an emission height of a few hundred km . if the signal is being modulated as its being generated , then @xmath16 should be of the order of a few ms and therefore a measurable quantity . if @xmath16 is significantly larger , then the modulation is happening after b s radio signal is generated . third , we will make an independent measurement of the orbital separation of the two pulsars , @xmath86 . if the timing of b s responses is precise enough , this might give us a more precise measurement of the mass ratio of a and b , which would increase the precision of some of the previous tests of general relativity carried out in this binary system . this is a key input parameter for the general tests on conservative gravity theories outlined in kramer & wex ( 2009 ) . in the ideal case that we can track the response times well , one might think of their reception at the earth as being equivalent to having a radio telescope at an altitude @xmath16 above b tracking a s rotation and then relaying the results live to earth . this analogy highlights how fortunate we are to have a phenomenon like b s responses . pccf , drl and mam acknowledge support from a wvepscor research challenge grant held by the wvu center for astrophysics . mam is an alfred p. sloan fellow . pulsar research at ubc is supported by an nserc discovery grant . ihs acknowledges sabbatical support from the atnf distinguished visitor program . 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in 2004 , mclaughlin et al . discovered a phenomenon in the radio emission of psr j0737@xmath03039b ( b ) that resembles drifting sub - pulses . the repeat rate of the sub - pulses is equal to the spin frequency of psr j0737@xmath03039a ( a ) ; this led to the suggestion that they are caused by incidence upon b s magnetosphere of electromagnetic radiation from a. here we describe a geometrical model which predicts the delay of b s sub - pulses relative to a s radio pulses . we show that measuring these delays is equivalent to tracking a s rotation from the point of view of an hypothetical observer located near b. this has three main astrophysical applications : ( a ) to determine the sense of rotation of a relative to its orbital plane ; ( b ) to estimate where in b s magnetosphere the radio sub - pulses are modulated and ( c ) to provide an independent estimate of the mass ratio of a and b. the latter might improve existing tests of gravitational theories using this system . [ firstpage ] binaries : general pulsars : general pulsars : individual ( psr j07373039a ) pulsars : individual ( psr j07373039b ) pulsar timing : general general relativity : general

dna for a primary colon tumor and adjacent normal colon tissue was purchased from biochain ( lot number a704198 ) . both samples came from the same donor , an 81-year - old male patient diagnosed with moderately differentiated adenocarcinoma . in vitro methylated and 5-aza - cytidine demethylated jurkat genomic dna samples were obtained from new england biolabs ( neb ) . formalin fixed , and paraffin - embedded ( ffpe ) colon carcinoma and matching normal tissue blocks were purchased from origene technical inc . these samples were derived from an 89-year - old male patient and ffpe - processed in 2001 . genomic dna was isolated using a recoverall total nucleic acid isolation kit ( applied biosystems / ambion ) according to the manufacture s recommendation . after purification , degraded genomic dna was size - selected on a 0.8% agarose gel . genomic dna from human blood cells was extracted as described previously20 . to obtain comparable , high - quality dna and to remove residual cellular proteins , all commercial dna samples were further purified using a standard phenol : chloroform : isoamyl alcohol ( 25:24:1 ) protocol20 . all cells were grown on 0.2% gelatin for at least two passages before isolation of dna . 30 ng to 1 g of human or mouse genomic dna was digested with 5 to 20 units of mspi ( neb ) in a 20 l reaction for 16 to 20 hours at 37 c . digested dna was phenol : chloroform : isoamyl alcohol purified as described above and dna pellets were resolved in 10 l eb buffer for end - repair . digested dna was filled in and adenylated in a 50 l reaction containing 10 units of klenow fragment ( 3 5 exo , neb ) , 40 m dgtp , 40 m 5 methylated dctp ( roche ) , 400 m datp and 1 neb buffer 2 . the reaction was incubated 20 min at 30 c followed by 20 min at 37 c . purified adenylated dna fragments were ligated with pre - annealed synthetic 5-methylcytosine - containing illumina adapters in a 50 l reaction consisting of 2,000 cohesive end units of t4 ligase ( neb ) , 10 l adenylated dna and 0.5 to 1.0 m of the adapter for 16 to 20 hours at 16 c . before size selection , the adapter - ligated dna was purified following the standard phenol : chloroform : isoamyl alcohol protocol . briefly , purified dna was run on a 3% nusieve 3:1 agarose gel until the bromophenol blue within the loading dye had run for 4 to 5 cm . to obtain 40 to 120 basepair and 120 to 220 basepair mspi digested genomic dna fragments , we excised adapter - ligated fragments that run at 150 to 230 basepair and 230 to 330 basepair , respectively . ( due to special characteristics of the illumina adapters , the lengths of the final dna fragments are not directly additive . ) to generate the 30 ng input rrbs library , 50 ng sheared and dephosphorylated escherichia coli k12 genomic dna was used as a carrier for gel size - selection and subsequent bisulfite conversion . size - selected dna was bisulfite - treated using epitect bisulfite kit ( qiagen ) . to validate and improve bisulfite conversion conditions of human genomic dna , we tested different bisulfite conversion protocols : ( i ) the manufacturer s standard 5-hour conversion protocol ( 99 c for 5 min , 60 c for 25 min , 99 c for 5 min , 60 c for 85 min , 99 c for 5 min , 60 c for 175 min ) ; ( ii ) two rounds of the standard conversion10 ; ( iii ) an approximately 14-hour phase conversion which included three additional cycles of 5 min of denaturation at 95 c followed by 3 h at 60 c after the 5-hour phase standard conversion4,20 . bisulfite - converted dna was eluted twice from the epitect spin column with 20 l pre - heated eb buffer per elution . analytical ( 10 l ) pcr reactions containing 0.5 l of bisulfite - treated dna , 0.2 m each of illumina pcr primers lpx1.1 and 2.1 and 0.5 u pfuturbo cx hotstart dna polymerase ( stratagene ) were set up to determine the minimum number of pcr cycles . reactions were performed under the following thermocycler conditions : 5 min at 95 c , n ( 20 s at 95 c , 30 s at 65 c , 30 s at 72 c ) , followed by 7 min at 72 c , with n ranging from 12 to 18 cycles . the final libraries were generated by large - scale amplification ( 8 25 l ) with each 25 l aliquot containing 2 to 4 l of bisulfite - converted template , 1.25 u pfuturbo cx hotstart polymerase , and 0.2 m each of illumina lpx1.1 as well as 2.1 pcr primers . qiaquick - purified pcr products were subjected to a final size - selection step on a 3% nusieve 3:1 agarose gel . sybr - green - stained gel slices containing adaptor - ligated fragments were excised . rrbs library material was recovered from the gel ( qiaquick ) and quantified by a quant - it ( invitrogen ) assay . rrbs libraries were sequenced on the genome analyzer ii ( illumina ) using the established single - end sequencing protocol . briefly , two reference sequences of size - selected mspi fragments are constructed in silico , one in which the genomic sequence is maintained as is , and one in which all cs are replaced by ts ( the latter reflects complete bisulfite conversion of cytosines into thymines ) . during the alignment , residual cs within each read are also converted into ts and aligned against the reference sequence that consists of all converted mspi fragments . the alignment itself uses a straightforward seed - and - extension algorithm , which identifies all perfect 12 bp alignments and extends without gaps from either end of the established seed . however , c - to - t conversions between the genomic dna sequence and the read are not counted as mismatches but marked for downstream methylation calling . the best alignment is kept only in cases where the second - best alignment has at least three more mismatches , while reads that do not meet this stringency criterion are discarded . bisulfite conversion rates are calculated as the number of genomic cytosines outside a cpg context that are unconverted , divided by the total number of cytosines outside a cpg context . disease - specific epigenetic alterations are typically more subtle than tissue - specific differences and changes related to cell differentiation , to which rrbs was originally applied4 . we therefore developed a bioinformatic pipeline that scores epigenetic alterations according to strength and significance , and links them to potentially affected genes . to that end , we collected a comprehensive set of regions of interest , which includes promoters , cpg islands , cpg island shores , enhancers , exons , introns , and repetitive elements . for each of these regions , the number of methylated and unmethylated cpg observations is determined , and a p - value is assigned using fisher s exact test . once all p - values are calculated , multiple - testing correction is performed separately for each region type using the q - value method21 , which controls the false discovery rate to be below a user - specified threshold ( typically 10% ) . a simple power calculation shows that for a given candidate region with coverage of 50 individual cpg measurements ( fig . 1a ) the power to detect a difference of 0% methylation vs. 20% methylation is 95% ( significance level of 0.05 ) . the software pipeline is implemented in python ( alignment processing module ) and r ( statistical analysis module ) . the source code package with documentation and demonstration data is available online ( supplementary note ) . future updates will be posted on http://rrbs-techdev.computational-epigenetics.org . using the software described in the previous section , we generated a comprehensive analysis of the rrbs experiments described in this paper . the supplementary website hosts all relevant results , including genome browser tracks visualizing the raw dna methylation data ; coverage statistics , mean methylation boxplots and clustering diagrams that provide an initial overview ; and scatterplots , pairwise correlations as well as statistical significance calls that facilitate in - depth analysis . dna for a primary colon tumor and adjacent normal colon tissue was purchased from biochain ( lot number a704198 ) . both samples came from the same donor , an 81-year - old male patient diagnosed with moderately differentiated adenocarcinoma . in vitro methylated and 5-aza - cytidine demethylated jurkat genomic dna samples were obtained from new england biolabs ( neb ) . formalin fixed , and paraffin - embedded ( ffpe ) colon carcinoma and matching normal tissue blocks were purchased from origene technical inc . these samples were derived from an 89-year - old male patient and ffpe - processed in 2001 . genomic dna was isolated using a recoverall total nucleic acid isolation kit ( applied biosystems / ambion ) according to the manufacture s recommendation . after purification , degraded genomic dna was size - selected on a 0.8% agarose gel . genomic dna from human blood cells was extracted as described previously20 . to obtain comparable , high - quality dna and to remove residual cellular proteins , all commercial dna samples were further purified using a standard phenol : chloroform : isoamyl alcohol ( 25:24:1 ) protocol20 . all cells were grown on 0.2% gelatin for at least two passages before isolation of dna . 30 ng to 1 g of human or mouse genomic dna was digested with 5 to 20 units of mspi ( neb ) in a 20 l reaction for 16 to 20 hours at 37 c . digested dna was phenol : chloroform : isoamyl alcohol purified as described above and dna pellets were resolved in 10 l eb buffer for end - repair . digested dna was filled in and adenylated in a 50 l reaction containing 10 units of klenow fragment ( 3 5 exo , neb ) , 40 m dgtp , 40 m 5 methylated dctp ( roche ) , 400 m datp and 1 neb buffer 2 . the reaction was incubated 20 min at 30 c followed by 20 min at 37 c . purified adenylated dna fragments were ligated with pre - annealed synthetic 5-methylcytosine - containing illumina adapters in a 50 l reaction consisting of 2,000 cohesive end units of t4 ligase ( neb ) , 10 l adenylated dna and 0.5 to 1.0 m of the adapter for 16 to 20 hours at 16 c . before size selection , the adapter - ligated dna was purified following the standard phenol : chloroform : isoamyl alcohol protocol . briefly , purified dna was run on a 3% nusieve 3:1 agarose gel until the bromophenol blue within the loading dye had run for 4 to 5 cm . to obtain 40 to 120 basepair and 120 to 220 basepair mspi digested genomic dna fragments , we excised adapter - ligated fragments that run at 150 to 230 basepair and 230 to 330 basepair , respectively . ( due to special characteristics of the illumina adapters , the lengths of the final dna fragments are not directly additive . ) to generate the 30 ng input rrbs library , 50 ng sheared and dephosphorylated escherichia coli k12 genomic dna was used as a carrier for gel size - selection and subsequent bisulfite conversion . size - selected dna was bisulfite - treated using epitect bisulfite kit ( qiagen ) . to validate and improve bisulfite conversion conditions of human genomic dna , we tested different bisulfite conversion protocols : ( i ) the manufacturer s standard 5-hour conversion protocol ( 99 c for 5 min , 60 c for 25 min , 99 c for 5 min , 60 c for 85 min , 99 c for 5 min , 60 c for 175 min ) ; ( ii ) two rounds of the standard conversion10 ; ( iii ) an approximately 14-hour phase conversion which included three additional cycles of 5 min of denaturation at 95 c followed by 3 h at 60 c after the 5-hour phase standard conversion4,20 . bisulfite - converted dna was eluted twice from the epitect spin column with 20 l pre - heated eb buffer per elution . analytical ( 10 l ) pcr reactions containing 0.5 l of bisulfite - treated dna , 0.2 m each of illumina pcr primers lpx1.1 and 2.1 and 0.5 u pfuturbo cx hotstart dna polymerase ( stratagene ) were set up to determine the minimum number of pcr cycles . reactions were performed under the following thermocycler conditions : 5 min at 95 c , n ( 20 s at 95 c , 30 s at 65 c , 30 s at 72 c ) , followed by 7 min at 72 c , with n ranging from 12 to 18 cycles . the final libraries were generated by large - scale amplification ( 8 25 l ) with each 25 l aliquot containing 2 to 4 l of bisulfite - converted template , 1.25 u pfuturbo cx hotstart polymerase , and 0.2 m each of illumina lpx1.1 as well as 2.1 pcr primers . qiaquick - purified pcr products were subjected to a final size - selection step on a 3% nusieve 3:1 agarose gel . rrbs library material was recovered from the gel ( qiaquick ) and quantified by a quant - it ( invitrogen ) assay . rrbs libraries were sequenced on the genome analyzer ii ( illumina ) using the established single - end sequencing protocol . briefly , two reference sequences of size - selected mspi fragments are constructed in silico , one in which the genomic sequence is maintained as is , and one in which all cs are replaced by ts ( the latter reflects complete bisulfite conversion of cytosines into thymines ) . during the alignment , residual cs within each read are also converted into ts and aligned against the reference sequence that consists of all converted mspi fragments . the alignment itself uses a straightforward seed - and - extension algorithm , which identifies all perfect 12 bp alignments and extends without gaps from either end of the established seed . however , c - to - t conversions between the genomic dna sequence and the read are not counted as mismatches but marked for downstream methylation calling . the best alignment is kept only in cases where the second - best alignment has at least three more mismatches , while reads that do not meet this stringency criterion are discarded . bisulfite conversion rates are calculated as the number of genomic cytosines outside a cpg context that are unconverted , divided by the total number of cytosines outside a cpg context . disease - specific epigenetic alterations are typically more subtle than tissue - specific differences and changes related to cell differentiation , to which rrbs was originally applied4 . we therefore developed a bioinformatic pipeline that scores epigenetic alterations according to strength and significance , and links them to potentially affected genes . to that end , we collected a comprehensive set of regions of interest , which includes promoters , cpg islands , cpg island shores , enhancers , exons , introns , and repetitive elements . for each of these regions , the number of methylated and unmethylated cpg observations is determined , and a p - value is assigned using fisher s exact test . once all p - values are calculated , multiple - testing correction is performed separately for each region type using the q - value method21 , which controls the false discovery rate to be below a user - specified threshold ( typically 10% ) . a simple power calculation shows that for a given candidate region with coverage of 50 individual cpg measurements ( fig . 1a ) the power to detect a difference of 0% methylation vs. 20% methylation is 95% ( significance level of 0.05 ) . the software pipeline is implemented in python ( alignment processing module ) and r ( statistical analysis module ) . the source code package with documentation and demonstration data is available online ( supplementary note ) . using the software described in the previous section , we generated a comprehensive analysis of the rrbs experiments described in this paper . the supplementary website hosts all relevant results , including genome browser tracks visualizing the raw dna methylation data ; coverage statistics , mean methylation boxplots and clustering diagrams that provide an initial overview ; and scatterplots , pairwise correlations as well as statistical significance calls that facilitate in - depth analysis . dna methylation in fresh - frozen and ffpe colon samples supplementary table 1 . pairwise correlation of dna methylation among the patient samples supplementary note .

bisulfite sequencing measures absolute levels of dna methylation at single - nucleotide resolution , providing a robust platform for molecular diagnostics . here , we optimize bisulfite sequencing for genome - scale analysis of clinical samples . specifically , we outline how restriction digestion targets bisulfite sequencing to hotspots of epigenetic regulation ; we show that 30ng of dna are sufficient for genome - scale analysis ; we demonstrate that our protocol works well on formalin - fixed , paraffin - embedded ( ffpe ) samples ; and we describe a statistical method for assessing significance of altered dna methylation patterns .

CLOSE Monday’s favorable ruling by the U.S. Supreme Court paves the way to allow gambling on sporting events at racetracks and casinos in the state. Brian Johnston, Asbury Park Press Dennis Drazin, Chairman and CEO of Darby Development LLC, the operators of Monmouth Park Racetrack, speaks to the media about the historic Sports Betting case decided by the U.S. Supreme Court on Monday May 14, 2018 in Oceanport, New Jersey. Monmouth Park is poised to begin taking sports bets in the near future. (Photo: Bill Denver/EQUI-PHOTO) The race is on around New Jersey to make sports betting a reality in the wake of Monday’s historic Supreme Court decision. With the highest court in the land overturning a decision by the Third Circuit Court of Appeals and declaring the 1992 Professional and Amateur Sports Protection Act unconstitutional, wagering on sporting events will be legal at the state’s racetracks and casinos. But when? Lawmakers in Trenton are working on legislation that will provide the framework for sports betting in the state, but Monmouth Park is hoping to be accepting wagers within two weeks, possibly without legislation in place. ``If I can do it in two weeks, that would be the goal,’’ said Dennis Drazin, president and CEO of Monmouth Park. ``No one told me I needed to stop or anything, the governor (Phil Murphy) has not said stand down.’’ Meadowlands operator Jeff Gural is taking a more cautious approach, waiting to see what rules and regulations emerge from Trenton. ``As soon as the legislature passes the legislation, and we know the tax rate and all the rules to be put in place, we would hope to be up and running by the start of the football season,’’ Gural said. ``I think the start of the NFL season is realistic.’’ Monmouth Park was poised to begin taking bets on NFL games using a manual system in 2014, before William Hill, its sports betting partner, had an automated system in place. But ``the leagues,’’ comprised of the four major professional sports leagues and the NCAA, got a temporary restraining order on Oct. 26, 2104 to stop the plan. While Drazin considered trying to get the William Hill Sports Book, a converted sports bar, up and running in less than two weeks, he seems inclined to wait for the automated to be in place this time. ``To start with one system and then have to switch over to another, we would have to analyze that from a business standpoint,’’ Drazin said. `` If the legislature puts a draft forward, they may say you can’t do any bets until you’re licensed through a formal regulatory process. Once that bill goes to the governor’s desk and he signs it and says I can’t take bets without going through the regulatory process, then whatever I’ve started I have to shut down.’’ Area lawmakers, however, seem eager to cash in what could be a financial windfall that could be worth more than a $1-billion annually for the state. ``I wouldn’t care if they opened because I think New Jersey should get on this right away and start making some money off of it for the taxpayers,’’ said Joann Downey, Democratic Assemblywoman for the 11th legislative district. Joe Asher, the CEO of William Hill US, feels sports wagering will be available fairly quickly, but isn’t rushing the process. ``The folks at Monmouth Park have been putting a lot of work in for a long time,’’ said Asher. ``Most of the infrastructure is done. The sports books are done. The TVs are hung. The issues are in the training of personnel. We’re cognizant of the unregulated approach of the last law. We need a proper vetting and training process. Dozens of people are necessary to do this. I think jobs will be posted today and tomorrow. It could take a couple of weeks. They are clearly in position to get going pretty quickly. ``We made the bet that we wanted to be ready if the Supreme Court ruled In our favor. We didn’t want to wait until today to start figuring it out.’’ Asher, in an interview later on WFAN, said, "From an operational perspective, we can be up and going at Monmouth Park within a couple of weeks. We need to put the very last bit of equipment in. We obviously need to start hiring people, training people. “Then there is the legal side to it, which we haven’t time to fully digest the Supreme Court’s opinion yet. We need to understand is there an opportunity to begin operations before New Jersey has actually adopted another law and the regulations surrounding it.'' Gural believes that whenever it happens, it’s going to be a positive thing for the state’s racing industry. ``I think it is going to help,’’ Gural said. ``I think it will bring people into the building. Hopefully there will be a spillover where they will bet on horseracing and sports. In talking to the companies in Europe who do this, their typical operation has sports and racing, combined. So they look at it as if there is a synergy with the two. We will have to see.’’ Stephen Edelson: [email protected]; @SteveEdelsonAPP ||||| The Supreme Court struck down a federal law that banned legalized sports betting on Monday, ending a lengthy legal battle in New Jersey that began after the state tried to legalize betting in 2012. So does this mean that people can now rush off and plunk down $100 on a National Basketball Association playoff game at an Atlantic City casino or from a smartphone? The answer is not simple. Can I bet at a casino or track in New Jersey? Not yet. According to state law, possible betting venues, which include racetracks and casinos, could begin accepting unregulated bets as soon as Monday, though gearing up to do so could realistically take time. Of the state’s potential betting sites, Monmouth Park Racetrack, near the Jersey Shore, is the furthest along, having partnered with a British bookmaker, William Hill, years ago to build a sports bar in anticipation of sports betting being legalized. The track also adopted its own regulations to abide by any potential ruling.

– The highest court in the land has struck down a law that banned sports betting in all states except Nevada, but some eager gamblers in New Jersey, the origin of the court battle, may still have to wait to wager. Per the New York Times, that's because even the Garden State, home to Atlantic City, doesn't yet have legislation in place to regulate sports betting in casinos and racetracks. Nor have those facilities had time to fully realize their sports betting operations. But now, even as state lawmakers are just beginning the process of creating a legal framework for the practice, business owners in New Jersey are hoping to start taking bets as soon as possible. For Monmouth Park Racetrack, that could be as soon as two weeks from now—even if legislation has not yet been enacted. As the Asbury Park Press notes, places like Meadowlands Racetrack, less than an hour outside New York City, aren't hitting the gas quite yet. Meadowlands operator Jeff Gural told the paper he intends to wait until legislators have their say before taking any bets. Monday's historic Supreme Court ruling struck down a 1992 federal law that has required states other than Nevada to ban gambling on sports. Nevada was grandfathered in at the time and has since had a monopoly on legal sports betting. New Jersey and its then-Gov. Chris Christie mounted the Supreme Court challenge to the 1992 law, arguing that the Professional and Amateur Sports Protection Act violates the 10th Amendment by forcing states to carry out a federal dictate. In a 6-3 ruling Monday, the high court agreed and struck down the law.

Japan Airlines Co. (9201) is investigating a fuel leak on a Boeing Co. (BA) 787 Dreamliner, the model that experienced an onboard fire last week in Boston and is now the subject of a U.S. safety review. The leak occurred Jan. 13 during maintenance at Tokyo’s Narita airport, Japan Airlines said yesterday in a statement. The jet was the same one that had a leak at Boston’s Logan International Airport on Jan. 8, the carrier said. “Fuel from a nozzle on the left wing used for discharging fuel leaked out,” Japan Airlines said in the statement. “This aircraft was not scheduled to be in service today and no passengers or working staff on the ground were injured. Appropriate inspections will be carried out.” The latest incident extended a week of operational setbacks for Boeing’s newest and most technologically complex jet. Japan Airlines’ first leak came Jan. 8, the day after the fire, followed by a cockpit window cracking on one 787 flown by All Nippon Airways Co. (9202) and an oil leak on another ANA Dreamliner. U.S. officials pronounced the 787 safe last week even as the Federal Aviation Administration disclosed the special review of the plane, citing concern stirred by the fire and other incidents. Electrical faults forced United Continental Holdings Inc. and Qatar Airways Ltd. to ground 787s in December. Window Repaired All Nippon repaired the cockpit window that cracked during a flight on Jan. 11, and the plane came back to Tokyo from Matsuyama in western Japan the next day, airline spokeswoman Megumi Tezuka said by telephone today. In the jet that leaked oil, a heat exchanger has been replaced, she said, adding that all 17 Dreamliners of the carrier are now in service. Japan Air spokeswoman Sze Hunn Yap today said investigation for the Jan. 13 fuel leak is continuing. Five of the carrier’s seven Dreamliners are in service, she said by phone. “We are aware of the incident and are working with our customer,” Paul Lewis, a spokesman for Chicago-based Boeing, said by e-mail. The two Japanese carriers are among the biggest operators of the Dreamliner, the first jet with a fuselage made chiefly of composite materials. The 787 entered commercial service more than three years late in 2011. Boeing has marketed the twin-engine jet as a way to open new routes between far-flung cities that don’t need the capacity of larger wide-bodies such as the 777 and the 747 jumbo jet. The 787 has become the planemaker’s fastest-selling model ever, with 848 orders through the end of 2012. To contact the reporters on this story: Ed Dufner in Dallas at [email protected]; Chris Cooper in Tokyo at [email protected] To contact the editors responsible for this story: Ed Dufner at [email protected]; Anand Krishnamoorthy at [email protected] ||||| Japan Airlines' (JAL) Boeing Co's 787 plane which encountered the mishap of a fuel leak arrives at New Tokyo international airport in Narita, east of Tokyo, in this photo taken by Kyodo, January 9, 2013. TOKYO/SEATTLE | TOKYO/SEATTLE (Reuters) - Japan Airlines Co (JAL) (9201.T) said on Sunday that a Boeing Co (BA.N) 787 Dreamliner jet undergoing checks in Tokyo following a fuel leak at Boston airport last week had leaked fuel during tests earlier in the day. An open valve on the aircraft caused fuel to leak from a nozzle on the left wing used to remove fuel, a company spokeswoman said. The jet is out of service after spilling about 40 gallons (roughly 150 litres) of fuel onto the airport taxiway in Boston due to a separate valve-related problem. In Boston, a different valve on the plane opened, causing fuel to flow from the centre tank to the left main tank. When that tank filled up, it overflowed into a surge tank and out through a vent. The spill happened as the plane was taxiing for takeoff on a flight to Tokyo on January 8. It made the flight about four hours later. The causes of both incidents are unknown, the JAL spokeswoman added. There is no timetable for the plane to return to service. "We are aware of the event and are working with our customer," Boeing spokesman Marc Birtel said of the leak in Tokyo. On Friday, the U.S. government ordered a wide-ranging review of Boeing's 787 Dreamliner, citing concern over a battery that caught fire on January 7, also on a JAL plane in Boston, and other problems. The government and Boeing insisted the passenger jet remained safe to fly. The 787 represents the boldest bet Boeing has made on a new plane in more than a decade, and because the aircraft required billions to develop, much of the company's financial performance is riding on its success. Boeing is trying to double production to 10 jets a month this year to cash in on nearly 800 orders. The eight airlines that operate the 50 jets delivered so far have expressed support for it, saying the mishaps are teething problems common with most new airplanes, and the 787's fuel savings make it an important addition to their fleets. JAL and local rival All Nippon Airways Co (9202.T) fly 24 Dreamliners. The review follows a slew of incidents that have focused intense scrutiny on the new plane. While many of the issues that have dogged the 787 are typically considered routine, their occurrence in quick succession on an aircraft that incorporates major new technology and has not seen wide use yet has sparked concerns about safety. In December, a 787 operated by United Airlines (UAL.N) and bound from Houston to Newark, New Jersey, was forced to land in New Orleans after a warning light in the cockpit indicated a generator had failed. Boeing later said a faulty circuit board produced in Mexico and supplied by UTC Aerospace Systems, a unit of United Technologies (UTX.N), had produced a false reading in the cockpit. A UTC Aerospace spokesman declined to comment. Also in December, two other 787s suffered problems with electrical panels. The fire on January 7 started when a lithium-ion battery used in an auxiliary power system ignited while the plane was parked at the gate. It burned for about 40 minutes before firefighters put the flames out, and smoke entered the cabin. Passengers and crew had already left the aircraft. <ID:L1E9C8B0V> On December 5, U.S. regulators said there was a manufacturing fault in 787 fuel lines and advised operators to make extra inspections to guard against engine failures. Last week, the plane had seven reported incidents, ranging from the fire to a cracked cockpit window. (Reporting by James Topham in Tokyo and Alwyn Scott in Seattle; Editing by Jeremy Laurence, Catherine Evans and Dale Hudson)

– Growing pains, or a more serious issue with Boeing's newest aircraft? A fuel leak is being investigated on a Japan Airlines Boeing 787 Dreamliner, adding to the long list of problems the aircraft has experienced in recent weeks, Bloomberg reports. Yesterday's leak follows problems including another fuel leak, a cracked windscreen, a fire, and braking problems. In the latest incident, workers at Tokyo's Narita Airport discovered fuel leaking from a nozzle on the left wing of the same plane that had a fuel leak in Boston last week. The airline says the plane was not meant to fly that day and no workers were injured. The FAA is reviewing the Dreamliner but says it is safe to fly and the eight airlines that operate the 50 jets delivered so far have expressed support for the model despite the series of issues, Reuters reports.

interest in tomosynthesis and its clinical applications has been revived by recent advances in digital x - ray detector technology . in tomosynthesis , an x - ray tube and an x - ray receptor tomosynthesis captures only one set of discrete x - ray projections that can be used to reconstruct any plane of the object retrospectively . this article will review and identify indications for x - ray digital linear tomosynthesis ( dlt ) . the chest phantom ( n-1 type , kyoto kagaku co. , tokyo , japan ) and the artificial pulmonary nodules of type n1 are depicted in the images [ figures 1 and 2 ] . the artificial pulmonary nodules were of the ground - glass opacity type ( 5 and 7 mm ) , and the spheres were of the same diameter and composition . for the dual - energy evaluation study , calcification was simulated using hydroxyapatite ( powder type ) . the relationship between the radiation attenuation properties of glass and those of real pulmonary nodules was correlated . tomosynthesis ( sonialvision safire ii , shimadzu co. , kyoto , japan ) and ct ( 64-slice somatom definition scanner ; siemens medical systems , forchheim , germany ) images of the artificial pulmonary nodules ( ground - glass opacity type ) . the quality of the images obtained by tomosynthesis imaging were clearer than those obtained by ct ( ct slice thickness : 5 mm ) . des - tomosynthesis and des radiography ( sonialvision safire ii ) of the same slice , demonstrates the content of the artificial pulmonary nodules with and without calcification . the high - contrast detectability phantom case having a clear , contrast detectability on des - tomosynthesis imaging produced for identical planes ( tomosynthesis acquisition angle : 40 ) . owing to its high sensitivity , normal - dose helical computed tomography ( ct ) is currently considered the gold standard for lung cancer detection . early reports indicate that low - dose helical ct has the potential to detect early lung cancer , and thus decrease morbidity . ct has the advantage of improved detection of lesion by eliminating visual clutter of overlying anatomy [ figure 1 ] . however , there are disadvantages of using ct when compared with chest radiography , such as high - radiation dose and cost . on the other hand , although chest radiography has advantages such as short examination time , low cost , and easy access , there are also important disadvantages such as low sensitivity and specificity . in chest radiography , the three - dimensional chest is projected onto a two - dimensional image . consequently , the ability to detect pathological findings is limited by the overlapping anatomy rather than by quantum noise . chest radiography has been shown to have a relatively low sensitivity for the detection of pulmonary nodules . the poor sensitivity of chest radiography precludes its use as a screening modality , despite its advantages of low cost , low dose , and wide distribution of devices . dlt is a method that provides some of the tomographical benefits of ct at a reduced radiation dose and cost and with an approach that can be easily implemented in conjunction with chest radiography . current state of dlt originates from the older technique of geometric tomography , which has largely fallen out of favor in chest imaging owing to positioning difficulty , high radiation dose , and residual blur from out - of - plane structures . dlt overcomes the difficulties of geometric tomography by permitting reconstruction of numerous slices of the image from a single low - dose acquisition of image data [ figure 1 ] . although improving detection of pulmonary nodules may be an early area of emphasis for the application of tomosynthesis , it also has potential for use in other areas of thorax imaging.[12 ] presence of calcification and stability of the mass over 2 years suggest its benign nature . a benign pattern of the calcifications has been considered necessary to exclude malignancy . in the evaluation of diffusely disseminated pulmonary nodules , identification of diffusely disseminated pulmonary nodules and calcifications in the nodules has been helpful in limiting the differential diagnosis . conventional radiography and conventional tomography have been used to detect calcifications , but they have been largely replaced by ct . however , ct has several inherent problems , including motion artifacts and the variety of reconstruction algorithms that are used by different ct scanners . dual energy subtraction ( des ) imaging has been proposed and investigated by many researchers as a means of reducing the impact of anatomic noise on disease detection by chest radiography . des involves making two radiographical projections of the patient using different energy x - ray beams . by exploiting the difference in the energy dependence of attenuation between bone and soft tissue , the bone contrast can be reduced to produce a soft tissue image and the contrast of the soft tissue can be reduced to produce a bone image . des digital radiography has been found to be useful in detecting calcifications within pulmonary masses . main drawback of the des technique , is that its projections may result in overlap of anatomical features ( e.g. , calcifications superimposed over the ribs or spine ) . des dlt is a new technique , and therefore there is no guidance for its integration into the clinical practice of chest radiography . the most reliable signs for discriminating between benign and malignant masses are the growth rate of the mass and presence or absence of calcifications within the mass . since calcifications are commonly observed in benign masses and no other radiographical characteristic is specific in characterizing a mass , it is important to detect and characterize calcification within lesions . using des dlt , the presence , distribution , and characteristics of calcifications in lung nodules can be assessed to an extent that is not possible with currently available ct imaging and projection - type des techniques . in addition , this technique is not susceptible to the problems of image overlap , partial volume effect , or shifting of the image plane [ figures 2 and 3 ] . calcified tuberculous foci in a 74-year - old man . comparison of the chest images obtained with x - ray radiography , digital tomosynthesis , des - tomosynthesis , and high - resolution ct ( hr - ct ) . des - tomosynthesis and hr - ct appear to have similar accuracy in detecting calcification in the pulmonary nodules . ideally , structures in a given plane of interest should be clearly displayed in the corresponding tomosynthesis reconstruction plane , whereas structures located outside of that plane should not be visible . essentially , the limited angular range of the tomosynthesis image acquisition geometry dictates that spatial resolution is limited in the dimension perpendicular to the detector plane . as a result , out - of - plane structures can not be completely removed from the reconstruction plane and are present in every such plane . however , most of these structures are not visible because various low - amplitude structures from projections overlap in the reconstruction plane , and therefore , appear blurred . out - of - plane structures from high - attenuation features can not be blurred and appear as multiple replicates in every reconstruction plane , except for the one in which the actual high - attenuation feature ( e.g. , rib ) is located . at one projection angle , these ghosting features are distributed along the line made by the x - ray source and the actual feature [ figure 4 ] . out - of - plane structures are present in every reconstruction plane , but most are not visible because the various low - amplitude structures from projections overlap each other in the reconstruction plane , and therefore are blurred . tomosynthesis is worthy of further evaluation because it is flexible and can accurately reproduce the shape of an artificial pulmonary nodule . tomosynthesis can be considered the modality of choice to detect and investigate simulated artificial pulmonary nodules with and without calcification .

the purpose of this paper is to identify indications for volumetric x - ray digital linear tomosynthesis ( dlt ) with single- and dual - energy subtraction techniques for artificial pulmonary nodule detection and compare x - ray dlt , x - ray digital radiography , and computed tomography .

SECTION 1. SHORT TITLE. This Act may be cited as the ``NAFTA Infrastructure Responsibility Act of 1996''. SEC. 2. FINDINGS. Congress finds that-- (1) the United States Customs Service collects over $600,000,000 per year in duties, fees, excise taxes, and fines from crossings of the border of the United States and Mexico; (2) although the United States Customs Service has collected increased duties, merchandise fees, and revenues from other commerce-related activities because of the ratification and implementation of the North American Free Trade Agreement, these increased revenues have not been accompanied by Federal funding for improving transportation facilities along the border of the United States and Mexico to ensure the free and safe flow of trade destined for all States and regions of the United States; (3) because of NAFTA, all 4 States along the border of the United States and Mexico will require significant investments in highway infrastructure capacity and motor carrier safety enforcement at a time when such States face extreme difficulty in obtaining funds to maintain current highway conditions; (4) the full benefits of increased international trade can be realized only if delays at the border of the United States and Mexico are significantly reduced; and (5) the increased revenues described in paragraph (2) should be used to provide Federal funding for transportation improvements required to accommodate NAFTA-generated traffic, in an amount above and beyond regular Federal transportation funding apportionments, obligational authority, and minimum allocation funds under title 23, United States Code, the Intermodal Surface Transportation Efficiency Act of 1991 (Public Law 102-240), and other laws. SEC. 3. DEFINITIONS. In this Act, the following definitions apply: (1) Commercial motor vehicle.--The term ``commercial motor vehicle'' means a motor vehicle that is used in commerce to transport passengers or property and has a gross vehicle weight rating of 26,001 or more pounds. (2) Major mexican border crossing facility.--The term ``major Mexican border crossing facility'' means a Mexican border crossing facility used by 150,000 or more northbound commercial motor vehicles in a calendar year. (3) Mexican border crossing facility.--The term ``Mexican border crossing facility'' means a Federal facility located in the United States that is used to enter the United States from Mexico. (4) Mexican border state.--The term ``Mexican border State'' means California, Arizona, New Mexico, and Texas. (5) Minor mexican border crossing facility.--The term ``minor Mexican border crossing facility'' means a Mexican border crossing facility used by less than 150,000 northbound commercial motor vehicles in a calendar year. (6) NAFTA.--The term ``NAFTA'' means the North American Free Trade Agreement. (7) Secretary.--The term ``Secretary'' means the Secretary of Transportation. SEC. 4. DIRECT FEDERAL ASSISTANCE FOR BORDER CONSTRUCTION AND CONGESTION RELIEF. (a) In General.--The Secretary shall make grants under subsections (b) and (c) to eligible recipients that submit to the Secretary an application that demonstrates need, due to increased traffic resulting from the implementation of NAFTA, for assistance in carrying out transportation projects that are necessary to relieve traffic congestion and improve enforcement of motor carrier safety laws. (b) Grants for Connectors to Mexican Border Crossing Facilities.-- The Secretary shall make grants to Mexican border States and units of general purpose local government in Mexican border States for the purposes of-- (1) connecting the National Highway System designated under section 103(b) of title 23, United States Code, with Mexican border crossing facilities; and (2) upgrading connectors described in paragraph (1) that are in existence as of the date of the grant. (c) Grants for Commercial Motor Vehicle Enforcement Facilities.-- The Secretary shall make grants to Mexican border States to construct, operate, and maintain commercial motor vehicle enforcement facilities. (d) Location of Projects.--All projects carried out using amounts from grants made available under this section shall be located in the United States and within 60 miles of the border of the United States and Mexico, except as specifically approved by the Secretary. (e) Apportionment of Amounts.-- (1) In general.--The Secretary shall apportion the amounts appropriated for a fiscal year for making grants under this section among the Mexican border States as follows: (A) 90 percent in the ratio which the number of major Mexican border crossing facilities in each Mexican border State bears to the total number of major Mexican border crossing facilities in all Mexican border States, as determined by the Secretary under paragraph (2). (B) 10 percent in the ratio which the number of minor Mexican border crossing facilities in each Mexican border State bears to the total number of minor Mexican border crossing facilities in all Mexican border States, as determined by the Secretary under paragraph (2). (2) Determinations.--The Secretary shall make each determination required by paragraph (1) concerning the number of commercial motor vehicles using a Mexican border crossing facility on an annual basis using the most recent calendar year information that can be obtained from the United States Customs Service. (f) Cost Sharing.--A grant under this section shall be used to pay the Federal share of the cost of a project. The Federal share shall be 80 percent. (g) Authorization of Appropriations.--There is authorized to be appropriated to carry out this section $100,000,000 for each of fiscal years 1997 through 2002. SEC. 5. BORDER INFRASTRUCTURE INNOVATIVE FINANCING. (a) Purposes.--The purposes of this section are-- (1) to encourage the establishment and operation of State infrastructure banks in accordance with section 350 of the National Highway System Designation Act of 1995 (109 Stat. 618; 23 U.S.C. 101 note); and (2) to advance transportation infrastructure projects supporting international trade and commerce. (b) Federal Line of Credit.--Section 350 of the National Highway System Designation Act of 1995 (109 Stat. 618; 23 U.S.C. 101 note) is amended-- (1) by redesignating subsection (l) as subsection (m); and (2) by inserting after subsection (k) the following: ``(l) Federal Line of Credit.-- ``(1) In general.--There is authorized to be appropriated from the general fund of the Treasury $98,000,000 to be used by the Secretary to enter into agreements with Mexican border States that have established infrastructure banks under this section to make lines of credit available to the States. ``(2) Amount.--The line of credit available to each participating Mexican border State shall be equal to the product of-- ``(A) the amount appropriated under paragraph (1); and ``(B) the quotient obtained by dividing-- ``(i) the contributions of the Mexican border State to the Highway Trust Fund during the preceding fiscal year; and ``(ii) the total contributions of all participating Mexican border States with infrastructure banks to the Highway Trust Fund during the preceding fiscal year. ``(3) Use of line of credit.--The line of credit under this subsection shall be available to provide Federal support in accordance with this subsection to a State infrastructure bank engaged in providing credit enhancement for projects to construct Federal-aid highways which will support a significant amount of traffic resulting from NAFTA. ``(4) Limitations.-- ``(A) In general.--A line of credit under this subsection may be drawn on only-- ``(i) with respect to a completed project described in paragraph (3) that is receiving credit enhancement through an infrastructure bank; ``(ii) when the cash balance available in the infrastructure bank is insufficient to pay a claim for payment relating to the project; and ``(iii) when all subsequent revenues of the project have been pledged to the infrastructure bank. ``(B) Third party creditor rights.--No third party creditor of a public or private entity carrying out a project eligible for assistance from an infrastructure bank shall have any right against the Federal Government with respect to a line of credit under this subsection, including any guarantee that the proceeds of a line of credit will be available for the payment of any particular cost of the public or private entity that may be financed under this subsection. ``(5) Interest rate and repayment period.--Any draw on a line of credit under this subsection shall-- ``(A) accrue, beginning on the date the draw is made, interest at a rate equal to the current (as of the date the draw is made) market yield on outstanding, marketable obligations of the United States with maturities of 30 years; and ``(B) shall be repaid within a period of not more than 30 years. ``(6) Relationship to state apportionment.--Funds made available to States to carry out this subsection shall be in addition to funds apportioned to States under section 104 of title 23, United States Code. ``(7) Mexican border state defined.--The term `Mexican border State' means California, Arizona, New Mexico, and Texas.''.

NAFTA Infrastructure Responsibility Act of 1996 - Authorizes the Secretary of Transportation to make grants to Mexican border States and local governments for certain transportation projects necessary to: (1) relieve congestion due to increased traffic resulting from implementation of the North American Free Trade Agreement (NAFTA); and (2) improve enforcement of motor carrier safety laws. Limits the Federal share of the costs of such projects to 80 percent. Authorizes appropriations. Amends the National Highway System Designation Act of 1995 to authorize appropriations to be used to enter agreements with Mexican border States that have established infrastructure banks to make available to them lines of credit for projects to construct Federal-aid highways which will support traffic resulting from NAFTA.

the study of systems with long range memory reveals some physical phenomena that are still not well understood , especially in systems which are outside the state of equilibrium or those in which the existence of anomalous diffusion is verified @xcite . here we show a simple analytical method which describes the behavior of the diffusion for large and intermediate times . in order to do that , we first generalize the concept of the diffusion exponent . then we present a conjecture to obtain , through the introduction of a time scaling factor @xmath0 , an analytical asymptotic result for the diffusion coefficient for long times . we obtain the scaling factor exactly and we show as well its universal behavior . we derive a numerical method to obtain the correlation function of velocities for an ensemble of particles from any given memory . we compare both methods and we obtain excellent agreement . the method has general application in the study of stochastic processes and it could be applied to several situations of physical interest . the generalized langevin equation ( gle ) is a stochastic differential equation which can be used to model systems driven by colored random forces . for the velocity operator @xmath1 this equation can be written as , @xmath2 where @xmath3 is the retarded friction kernel of the system , or the memory function . here , @xmath4 is a stochastic noise subject to the conditions @xmath5 , @xmath6 , and @xmath7 where @xmath8 is the correlation function for @xmath4 , and the angular brackets denote an average over the ensemble of particles . equation ( [ eq2 ] ) is kubo s fluctuation dissipation theorem ( fdt ) @xcite . the presence of the kernel @xmath3 allows us to study a large number of correlated processes . in the real world , the vast majority of problems are non - markovian , i.e. , there is correlation between the various stages of dynamic evolution . this property is what we call memory , and it makes remote events of the past important to dynamic events in the present time . using the gle it is possible to study the asymptotic behavior of the second moment of the particle movement , @xmath9@xmath10 which characterizes the type of diffusion presented by the system . here , @xmath11 is the diffusion coefficient as a function of time . moreover , for an asymptotic behavior of the form @xmath12 ^ { \pm 1 } } , \label{x2g}\ ] ] we shall define respectively an @xmath13 diffusive behavior . here the exponent @xmath14 arises in analogy with the critical exponents in a phase transition . for example , in the two - dimensional ising model the critical exponent for the specific heat is @xmath15 because it does not have a power law behavior ; rather it has @xmath16 behavior for temperatures @xmath17 close to the transition temperature @xmath18 . this generalized nomenclature is pertinent here since there are quite a large number of possibilities of combinations for logarithmic and power law behaviors . in this way the behavior of @xmath11 can be determined using @xmath19 where @xmath20 , with @xmath21 , and @xmath22 is the laplace transform of @xmath23 . for @xmath24 and normal diffusion this is the kubo formula @xcite . the limits can be justified using the final value theorem ( fvt ) for a laplace transform @xcite , i.e. , for any function @xmath25 with laplace transform @xmath26 then @xmath27 . now a laplace transform of the integral gives @xmath28 , and we end up with the equation above . now we multiply eq . ( [ eq1 ] ) by @xmath29 and take the average over the ensemble , with @xmath6 , to obtain a self - consistent equation for @xmath23 in the form @xmath30 we then laplace transform eq . ( [ eq6 ] ) to get @xmath31 time correlation functions play a central role in non - equilibrium statistical mechanics in many areas , such as the dynamics of polymeric chains @xcite , metallic liquids @xcite , lennard - jones liquids @xcite , ratchet devices @xcite , spin waves @xcite , heisenberg ferromagnets and dense fluids @xcite . consequently to invert this transform , or a similar one , is crucial . unfortunately , in most cases it is not an easy task . in those situations , the use of numerical methods is an alternative to overcome this problem . our main objective here is to show a process to obtain the asymptotic behavior analytically . although the method can be applied to several situations , we concentrate here on the analysis of diffusion . we claim that after a `` transient time '' @xmath32 , i.e. , for @xmath33 , the leading term for @xmath11 will fulfill eq . ( [ eq9 ] ) within a given approximation . in this context @xmath24 is equivalent to @xmath34 . now we imposed the scaling @xmath35 in order to determine @xmath0 we rewrite eq . ( [ eq9 ] ) as @xmath36 where @xmath37 the derivative of eq . ( [ eq9b ] ) yields @xmath38 } ] /f(t ) , \label{r1}\ ] ] while from the fvt we have @xmath39 the relative diference @xmath40}]/\lambda \label{dr}\ ] ] should evolve to zero as @xmath41 . for @xmath42 this yields the exact value @xmath43 } . \label{lambda}\ ] ] the scaling works as long as the gle , eq . ( [ eq7 ] ) , works . to obtain @xmath44 we need more information about @xmath45 , which may be different for every system . however , since our interest is in the asymptotic behavior , we can expand @xmath45 , in taylor or laurent series around @xmath46 , in the form @xmath47 , \label{gammag}\ ] ] where @xmath48 , @xmath49 , and @xmath50 are positive constants . note that we give especial attention to @xmath51 , since it will give us the behavior pointed out in eq . ( [ x2 g ] ) . for @xmath52 this gives a diffusion with exponent @xmath53 ; for @xmath54 this gives an @xmath55 , and for @xmath56 and @xmath57 we get an @xmath58 diffusion . if @xmath45 has another contribution , besides @xmath51 , that can not be expanded at the origin we keep it and expand the other parts . however , most of the memories in the literature can be cast in the form eq . ( [ gammag ] ) for small @xmath59 . now we introduce eq . ( [ gammag ] ) into eq . ( [ lambda ] ) to obtain @xmath60 for @xmath61 , and @xmath62 for @xmath63 . notice that it does not depend on @xmath48 , @xmath49 , or @xmath50 , which suggests a universal behavior . in our conjecture some points deserve attention : first , we are considering integrals , of the form eq . ( [ eq9 ] ) , where the function @xmath23 is well behaved , and limited to @xmath64 , since @xmath65 . @xmath23 is such that it always has a well - defined behavior for finite @xmath66 , even when the integral diverges as @xmath67 , as in superdifusion . second , @xmath11 must have a leading term as @xmath67 , which determines the diffusion . for example , the inverse laplace transform of @xmath22 is @xmath68 here the real number @xmath69 is such that all the singularities lie at the left of the line joining the limits . consider now eq . ( [ gammag ] ) with @xmath70 , and @xmath71 ; then @xmath72 , and @xmath73 where we have done the transformations @xmath74 and @xmath75 . for @xmath76 the only pole is at @xmath77 , and the condition in @xmath78 will be automatically satisfied . now by direct integration on eq . ( [ eq9 ] ) we obtain @xmath79 . from the scaling we get the equivalent result @xmath80 note that the above exact result is not only for power laws , but for any function behaving as a power law for large @xmath66 . we confirm as well the relation @xmath81 , obtained by morgado _ et al . our results can be readily expressed as @xmath82 the factor @xmath0 depends only on the diffusion exponent @xmath53 , consequently it is universal . moreover it will be the same for @xmath53 or @xmath13 . for normal diffusion @xmath83 , or for @xmath84 , @xmath85 . however , we still can obtain the final value . consider as example the langevin equation without memory ; for that we have @xmath86 and @xmath87 . from eq . ( [ eq9b ] ) we get @xmath88 while direct integration gives @xmath89 in this case the scaling yields correctly the wanted final value . equation ( [ eq6 ] ) imposes as well some requirements on @xmath23 . first its derivative must be null at the origin , i.e. , the integral in the right hand side must be null at @xmath90 . this is true except for non analytical memories , such as @xmath91 functions . indeed , we do not expect exponential behavior of the form @xmath92 with a discontinuous derivative at the origin @xcite . second , in eq . ( [ eq1 ] ) , for a bath of harmonic oscillators the noise can be obtained as @xcite @xmath93 d \omega , \label{noise}\ ] ] where @xmath94 are random phases and @xmath95 is the noise spectral density . the fdt yields @xmath96 this shows that the memory is an even function of @xmath66 . an analytical extension of @xmath45 in the whole complex plane has the property @xmath97 . consequently , from eq . ( [ eq7 ] ) , @xmath98 , or @xmath99 . in short , it requires well - behaved functions and derivatives . even functions have zero derivatives at the origin as required before . let us consider the spectral density @xmath100 this is a generalization of the debye density of states . here @xmath101 is a dimensionless constant , and @xmath102 is a cutoff frequency . for @xmath103 we get anomalous diffusion . in particular , for @xmath104 we introduce eq . ( [ dens ] ) into eq . ( [ gamman ] ) to obtain @xmath105 with the laplace transform @xmath106 } . \label{gamzf}\ ] ] first , we have the analytical function @xmath107 ; second , from eq . ( [ lambda ] ) we obtain @xmath108 , exactly . this is ballistic diffusion of the form @xmath109 . now we compare the analytical asymptotic with a numerical solution of eq . ( [ eq6 ] ) . to do this , we rewrite this equation in a discrete form , and then we expand it up to terms of order @xmath110 to obtain @xmath111 where @xmath112 , is the time derivative of @xmath23 of order @xmath113 . note that this expansion eliminates all the even derivatives . now we can obtain all @xmath114 from the sequence of the previous value of @xmath23 , starting from @xmath115 . from these values , its possible to get the diffusion coefficient through direct integration of eq . ( [ eq9 ] ) . in fig . [ fig1 ] we plot the correlation function @xmath23 as a function of time @xmath66 . the curves correspond to the numerical solution , and are calculated using eq . ( [ eq14 ] ) , and eq . ( [ gammaf ] ) with @xmath116 . for curve _ a _ , @xmath117 , and @xmath118 ; for curve _ b _ , @xmath119 and @xmath120 . in fig . [ fig2 ] we plot the diffusion coefficient @xmath11 as a function of time @xmath66 . the oscillatory curves corresponds to the numerical solution and are calculated from the data of fig . 1 . the curves without oscillations correspond to the analytical asymptotic limit , eq . ( [ eq9b ] ) , with memory eq . ( [ gamzf ] ) . here we see that the asymptotic curves are mean values of the oscillatory ones . in this range the fit yields for curve _ a _ , @xmath121 , and for curve _ b _ , @xmath122 @xmath123 @xmath124 . we see in curve _ b _ that the two curves collapse onto a single one . here the transient time @xmath32 to which we refer before eq . ( [ eq9b ] ) is a decreasing function of @xmath125 . the value of @xmath0 approaches the exact value @xmath126 as the ratio @xmath125 decreases , or as time increases . this shows the efficiency of the scaling ; even before convergence is fully established , curve _ a _ , the asymptotic curve gives us an average value that can be used to understand the main characteristics of the process . consider now @xmath127 , exactly . that means @xmath128^{-1}$ ] or @xmath129^{-1}$ ] , and by direct integration we get @xmath130 exactly . this is ballistic @xmath131 diffusion . if we apply eq . ( [ eq9b ] ) we obtain the same result with @xmath132 . since from the relations ( [ gammag ] ) and ( [ lam ] ) the value of @xmath0 does not depend on @xmath133 , this result is exactly what we get from eq . ( [ gamzf ] ) . there are important differences between the @xmath109 diffusion , which according to the khinchin theorem @xcite is ergodic , and the @xmath131 diffusion , which does violate ergodicity . this distinction was not possible before the generalization of the diffusion exponent we present here . in this work we generalize the concept of the diffusion exponent , and we propose a conjecture to investigate the asymptotic limits of anomalous diffusion , through the introduction of a time scaling factor @xmath0 . we obtain the scaling parameter exactly and we show that it is universal and depends only on the diffusion exponent . we analyze the ballistic diffusions @xmath109 and @xmath131 , both analytically and numerically . the method can be useful as well to analyze large amounts of data in stochastic processes @xcite , and in different fields of science where is necessary to inverse a laplace transform of the form of eq . ( [ eq7 ] ) . the phenomenon of diffusion also poses challenges in the understanding of fundamental concepts in statistical physics , such general properties as the correlation function @xcite , ergodicity @xcite , and the khinchin theorem @xcite . in nonlinear phenomena , such as growth and etching @xcite , analytical results are rather difficult to obtain . in this way we hope that this work may inspire research into similar asymptotic limits . we thank the brazilian agencies cnpq , capes , funcap , and fap / df for financial support . m. h. vainstein , r. morgado , f. a. oliveira , f.a.b.f . de moura , m.d . coutinho - filho , physics letters a * 339 * , 33 ( 2005 ) . for a review see u. bulacani , m. h. lee , v. tognett1 , physics reports * 373 * , 409 ( 2003 ) .

we investigate through a generalized langevin formalism the phenomenon of anomalous diffusion for asymptotic times , and we generalized the concept of the diffusion exponent . a method is proposed to obtain the diffusion coefficient analytically through the introduction of a time scaling factor @xmath0 . we obtain as well an exact expression for @xmath0 for all kinds of diffusion . moreover , we show that @xmath0 is a universal parameter determined by the diffusion exponent . the results are then compared with numerical calculations and very good agreement is observed . the method is general and may be applied to many types of stochastic problem . .

despite the advances carried out so far , the origin of the gamma - ray bursts ( hereafter grbs ) remains unknown . the identification of absorption lines in the optical spectrum of grb 970508 strongly supports models arising from sources at cosmological distances ( metzger et al . 1997 ) , but there is still a lack of knowledge on the mechanisms originating these enigmatic phenomena . one of the most important clues that could clarify the nature of the grbs would be the detection of a repeater behaviour . initial studies showed an apparent evidence of repetition for the batse 1b catalogue ( quashnock and lamb 1993 ) , suggesting that it would be possible to have an excess of pairs of grbs clustered in both time and space ( wang and lingenfelter 1995 ) . this fact was not confirmed by the work carried out using the batse 2b catalogue ( brainerd et al . 1995 ) , although other studies provided marginal evidence for both temporal and angular clustering ( petrosian and efron 1995 ) . analyses based on autocorrelations with data from the batse 3b catalogue did not find any evidence of repetition ( bennett and rhie 1996 ) and have imposed several constraints to the number of repeaters ( tegmark et al . finally , recent studies confirm the lack of repetition in the 4b catalogue and lead to an upper limit to the repetition rate of @xmath2 burst source@xmath3 yr@xmath3 ( hakkila et al . 1997 ) . the batse 4b catalogue was obtained by the batse experiment on board the _ cgro _ satellite and contains 1637 grbs detected from april 1991 to august 1996 ( paciesas et al . the batse experiment consists of eight identical detector modules , placed at the corners of the _ cgro _ spacecraft and covering energy channels from @xmath4 kev to @xmath5 2 mev . it provides error boxes with a minimum radius of @xmath6 ( 1@xmath7 confidence level , fishman et al . batse is detecting bursts at a rate of 0.8 bursts per day . the bursts are daily added to the so - called current grb catalogue , which contains the batse 4b catalogue plus all bursts detected after august 1996 . when this study was started , the catalogue contained 1905 sources ; this sample constitutes the basis of the present work . the watch x - ray all - sky monitor is based on the rotation modulation principle ( lund 1986 ) . the instrument has a circular field of view of 4 steradians and an effective area of @xmath5 30 @xmath8 ( averaged over the field of view ) . position sensitivity is achieved using the rotation collimator principle , with the collimator grids rotating with a frequency @xmath9=1 hz . the phoswich detectors consist of interleaved scintillator - strips of nai and csi crystals . the geometric area of the scintillator is 95 @xmath8 . four units were mounted on board the soviet _ granat _ satellite in a tetrahedral configuration covering the whole sky , and one unit on board the european space agency _ eureca _ spacecraft . the total energy range is 8 - 80 kev , therefore overlapping with the lower batse energy band . watch / granat detected bursts in 1990 - 94 and watch / eureca in 1992 - 93 , thus both experiments also overlapped in time with batse . one of the main advantages of watch was the capability of locating bursts with relatively small error boxes ( @xmath10 error radii with @xmath5 1@xmath11 ) ( brandt et al . 1990 ) . watch / granat detected 47 grbs in this period and watch / eureca 12 ( castro - tirado et al . 1994 , brandt et al . 1994 , sazonov et al . two grbs ( grb 920814 and grb 921022 ) were detected by both the watch / granat and watch / eureca experiments . therefore , the sample of watch grbs used in this study comprises 57 grbs : 45 watch / granat bursts , 10 watch / eureca bursts and the above - mentioned two grbs . batse also detected 27 of them . [ figure1 ] shows the sample of 57 watch grbs used in this study . the distribution of time amplitudes for grbs shows two classes of bursts : a ) durations shorter than @xmath5 2 s and b ) longer than @xmath5 2 s ( kouveliotou et al . 1993 ) . it was noticed that the energy spectra of the short bursts were generally harder than those of the long ones ( kouveliotou et al . 1993 , lestrade et al . 1993 ) . the fraction of short events in the watch sample is smaller than that in the 4b catalogue . this fact can be justified by at least three selection effects : \i ) the availability of watch for localizing sources is governed by the rotation speed of the collimator grids ( 1 hz ) . so , a source needs to be bright enough for at least one rotation of the modulation collimator in order to be localized , implying a burst duration longer than 1 s. in contrast , the batse experiment is able to detect bursts with durations as short as 64 ms . \ii ) the low energy band of the watch experiment ( @xmath58 - 20 kev ) is sensitive to the soft grbs , below the batse lower limit ( @xmath525 kev ) , which generally belong to the class of bursts with durations longer than 2 s. \iii ) on the other hand , since watch is about an order of magnitude less sensitive than the large - area detectors of batse , the watch catalogue contains bursts which are brighter than those in the batse sample . the above three reasons explain why the grbs in the watch sample are longer , softer and brighter than the average batse 4b bursts . this study is the first known attempt to search for repeaters combining data of @xmath12-ray experiments flying on board different satellites . the method proposed makes use of the so - called `` simultaneous bursts '' and is suitable to correlate grb data provided by experiments that overlap partially or totally in time . in the future , this work could also be used to detect systematic pointing errors between different @xmath12-ray experiments , allowing to improve their capability for locating grbs . in this section we outline the methodology proposed to carry out the study . first , we exclude the simultaneous bursts ( @xmath13 2.1 ) and calculate the so - called `` added correlation '' function between the watch and batse samples ( @xmath13 2.2 ) . afterwards , 1500 watch catalogues are simulated ( @xmath13 2.3 ) in order to calculate the expected value of the `` added correlation '' function . then the distribution of the overlapping function for real and random overlaps is obtained ( @xmath13 2.4 ) and finally the probability of having different number of repeaters ( @xmath13 2.5 ) is found . we consider that there is a common source in both samples when the emission of a repeater is detected at least twice , once by each experiment and the detections are separated in time . thus , the same grb detected simultaneously by both experiments considered as a common source . our study is aimed at searching common sources detected by both watch and batse experiments . the positions of 27 simultaneous bursts detected by watch and batse are in good agreement . if batse @xmath14 error boxes are considered , there are 20 overlaps with watch @xmath10 boxes . instead , if @xmath10 error boxes are taken into account there is only one burst ( grb 920714 ) that does not overlap . these 27 bursts were excluded from the batse sample of 1905 sources , because they are obviously the same sources detected by watch . therefore the sample was reduced to 1878 bursts . nevertheless , the simultaneous bursts were considered in further calculations ( @xmath13 2.4 ) , because they provide information on the overlapping expected for a repeater detected by both batse and watch . recurrence , even in a single case , would be immediately obvious if we had locations with no errors . however , the locations provided by batse and watch , while numerous , have inaccuracies and consequently a statistical analysis is required to demonstrate , or limit , the presence of common sources . if any repeater is present in both catalogues , an excess in the overlap between the error boxes of both catalogues would be expected . we define the overlapping function between the @xmath15-th watch and the @xmath16-th batse error boxes as the following integral over the galactic coordinates @xmath17 and @xmath18 : @xmath19 a f_j w_i(l , l_i , b , b_i ) b_j(l , l_j , b , b_j ) d@xmath20\ ] ] where @xmath21 is a normalization factor computed in such a way that @xmath22 remains between 0 and 1 . @xmath23 is the batse exposure correction for the batse @xmath16-th burst . @xmath24 and @xmath25 are the galactic coordinates of the centre of the @xmath15-th watch and the @xmath16-th batse error boxes , @xmath26 is the distance between the @xmath15-th watch and the @xmath16-th batse burst , and @xmath27 are the @xmath10 radii of the @xmath15-th watch and the @xmath16-th batse error boxes . @xmath28 is a gaussian - like normalized probability distribution given by the following expression : @xmath29 with @xmath30 , and @xmath31 the distance between the integration point and the centre of the @xmath16-th batse burst ; @xmath32 @xmath33 is analogous to @xmath34 based on watch coordinates . although we are aware that the errors of batse locations do not follow a single gaussian distribution ( see briggs et al . 1998 ) , we consider that , for our purposes , we can extend the gaussian approximation from 1@xmath7 to 3@xmath7 . this is a very appropriate and useful approximation which has been frequently used in the past ( fisher et al . 1987 , bennett and rhie 1996 ) , providing stringent upper limits on the 3b catalogue ( tegmark et al . 1996 ) . on the other hand , the error introduced in @xmath22 by considering only overlaps between 3@xmath7 error boxes , instead of assuming unlimited error boxes , is less than 0.1% , irrelevant for our final conclusions . in the approximation that @xmath35 and @xmath36 ( which is quite accurate , since typical values are @xmath37 and @xmath38 a few degrees ) , @xmath22 approximately depends on @xmath26 like @xmath39 , so it decreases rapidly when both probability distributions are not close to each other . @xmath22 provides a measurement of whether both grbs originated from the same source or not . based on the former arguments , we define the `` added correlation '' @xmath40 as follows : @xmath41 @xmath40 is a parameter which is very sensitive to the presence of common sources in both catalogues . the larger the number of common sources , the higher the value of @xmath40 obtained . our study is based on the comparison of the `` added correlation '' @xmath40 calculated for the real watch catalogue ( renamed as @xmath42 ) with those obtained for 1500 watch simulated catalogues ( renamed as @xmath43 ) . @xmath40 is the generalization for two probability distributions ( watch and batse ) of the @xmath44 statistics introduced by tegmark et al . @xmath45 is corrected by the batse and watch exposure maps , the first one is taken into account in the term @xmath23 included in the definition of @xmath22 , whereas the second one is considered to simulate the watch catalogues for which @xmath45 are calculated . monte carlo simulations of 1500 watch - like catalogues have been performed . they provided 1500 values for @xmath40 called @xmath43 . in order to determine reliable values for them , the exposure maps of the watch / granat and watch / eureca instruments were taken into account . the failure of unit number 2 on board _ granat _ , and the limited field of view and the earth blockage of watch / eureca , made it that none of the experiments covered uniformly the sky . the watch / granat map shows larger exposures towards the galactic centre whereas the watch / eureca one is under exposured towards the equatorial poles ( brandt 1994 , castro - tirado 1994 ) . if we assume that grbs occur randomly both in space and time , the probability of detecting a grb in a given direction is proportional to the exposure time spent on that region . therefore for each simulated set of 57 bursts , 45 of them follow the watch / granat exposure map , 10 the watch / eureca exposure map and the remaining two bursts ( representing grb 920814 and grb 921022 ) follow both exposure maps simultaneously . the simulated watch - like sets have the same error radii than the real watch catalogue . we call random overlaps to overlaps between the batse bursts and the simulated watch events . the random overlaps provide a set of @xmath22 that follows a distribution so - called @xmath46 . in order to estimate such distribution , the value of the overlapping functions @xmath22 are calculated for all the overlaps between the batse sample and 50 simulated watch catalogues . it shows a mean value @xmath47 and a deviation @xmath48 . @xmath46 provides the expected value of the overlapping function when there is a casual overlap between two boxes ( not due to arise from the same source ) . the majority of the random overlaps shows very low values of the overlapping function because they tend to occur at the border of the error boxes in the tail of the probability distribution . on the other hand , the overlapping function , @xmath22 , for each of the 27 batse - watch simultaneous pairs is calculated . the distribution of these 27 values of @xmath22 is called @xmath49 . the mean value of the real overlaps , @xmath50 , and the deviation @xmath51 . as expected @xmath52 is greater than @xmath53 . this fact can be explained taken into account that the probability distributions due to a single grb detected by both experiments tend to be close to each other , compared with two grbs randomly located in the same zone in the sky . thus , the random overlaps tend to occur in the tail of the probability distribution , thus forcing @xmath22 to be very low . moreover , the lower sensitivity of watch in comparison to batse implies that the 27 simultaneous bursts are brighter than the average batse bursts , ( as the radii of the error boxes depend on the intensity ) and therefore they have smaller error boxes , thus making @xmath52 larger than @xmath54 . the next step is to consider @xmath49 as the expected distribution of @xmath22 for repeaters . this consideration is based on the two following assumptions : 1 . there is little variation with time on the sensitivity of both experiments . a change in the sensitivity imply into differences in the sizes of error boxes and thus in the @xmath22 values . if more accuracy is desirable , then it is necessary to know how the sensitivity of both instruments evolves , in order to correct the sizes of the error boxes depending on the date of detection . 2 . the intensities of different bursts from a repeater source do not change significantly in time . therefore the sizes of the repeater error boxes remain approximately the same . a more complicated study would deal with the time evolution of the repeater sources . the set of 1500 @xmath45 s calculated using mock watch catalogues follows a gaussian probability distribution ( hereafter called @xmath55 , see fig . [ figure2 ] ) . the simulated watch catalogues were generated only using the exposure maps and they only contain accidental overlaps , because the simultaneous grbs were excluded from the sample . therefore @xmath55 gives us the expected value of the `` added correlation '' when watch and batse catalogues do not share any source . assuming that @xmath49 represents the expected value of the overlapping function for repeater sources , we can introduce trial repeaters and construct the @xmath45 s probability distributions @xmath56 for different number of repeaters , @xmath57 , by the following symbolic expression : @xmath58 @xmath57 being the number of repeaters . if we take any `` added correlation '' @xmath45 of @xmath59 repeaters with a probability given by @xmath55 , and then we add the contribution to @xmath45 of any repeater with overlapping function given by @xmath49 and subtract the contribution of any random overlap given by @xmath46 , we get a new `` added correlation '' @xmath45 . this process can be repeated by introducing other real and random overlaps , providing a new set of @xmath45 s . once a trial repeater has been introduced , this set of @xmath45 s will follow a different probability distribution from @xmath55 , called @xmath60 . thus , @xmath60 provides the expected values of @xmath45 when batse and watch share one source . similarly , this method can be applied for @xmath61 repeaters , in order to obtain the distributions of the `` added correlations '' for different number of repeaters , @xmath62 . [ figure3 ] shows the probability distributions @xmath63 obtained using this procedure . the intersection between @xmath42 and the distributions @xmath56 provides @xmath64 values called @xmath65 . based on the @xmath64 values of @xmath66 we can obtain the distribution of @xmath66 for @xmath67 . taking into account that the maximum number of allowed coincidences is @xmath68 , the distribution of @xmath66 s can be normalized by imposing @xmath69 . then , @xmath66 provides the probability that the batse and watch catalogues share @xmath57 sources ( see fig . [ figure4 ] ) . as it can be seen in fig . [ figure2 ] , the mean value of the `` added correlation '' for the simulated catalogues , @xmath70 , is even larger than the `` added correlation '' for the real watch and batse catalogues , namely @xmath71 . this implies that our results agree qualitatively with the absence of common sources . the fact that we have preferred to simulate watch catalogues instead of batse ones is only due to the computing time , because it is more efficient to simulate sets of 57 bursts in comparison with groups of 1906 members . in spite of this fact , the roles of both catalogues were exchanged in order validate the method , applying the process explained in section @xmath13 2 to 50 batse simulated catalogues . only with 50 catalogues the values obtained for @xmath42 and @xmath72 differ by less than 5% from those obtained when watch catalogues were simulated . . the first and third column represent the number of repeaters , @xmath57 . the second and the fourth ones give the probability of having @xmath57 repeaters . [ cols="^,^,^,^",options="header " , ] the probability distributions @xmath56 are shown in fig . [ figure3 ] and the deduced values of @xmath66 are given in table 1 and displayed in fig . [ figure4 ] . as it is shown in table 1 , @xmath66 decreases with @xmath57 , showing the maximum value when batse and watch do not share any source . thus , our results support the lack of common sources . furthermore , the number of common sources is @xmath73 with a @xmath1 confidence level ( see table 1 ) , which means a @xmath0 of the whole sample . this percentage is similar to the @xmath74 upper limit imposed to the 1b catalogue ( strohmayer et al . the results are also in good agreement with the studies carried out with the batse 3b ( tegmark et al . 1996 ) and 4b catalogues ( hakkila et al . 1998 ) , which did not find evidence of repetition . a possible reason to explain our results could be due to the different sensitivity of the experiments , as watch is sampling the strongest bursts and batse is also detecting a fainter population . the different populations of objects found inside watch and batse error boxes could support this idea ( gorosabel and castro - tirado 1998a , 1998b ) . in this study we have developed a method that allows us to search for grbs common to two catalogues of sources , each one based on a different instrument . the method makes use of the grbs detected simultaneously by both experiments , so it is necessary that the experiments overlap in time . we have applied the method to the watch ( watch / granat + watch / eureca ) and batse ( batse 4b + bursts detected after august 1996 ) catalogues . we conclude that there is no evidence of recurrent activity of watch bursts in the batse sample . we claim ( with a @xmath1 confidence level ) that no more than a @xmath0 of the 57 grbs detected by watch are present in the sample of 1905 batse bursts ( excluding the simultaneous bursts ) . however , the possibility of finding repeaters in each single catalogue can not be ruled out . our results support models which do not predict repetitions of grbs ( for instance the merging of neutron stars at cosmological distances ) . j. gorosabel wishes to thank b. montesinos for revising the paper and for fruitful comments . this work has been partially supported by spanish cicyt grant esp95 - 0389-c02 - 02 . brandt , s. , lund , n. , and castro - tirado , a.j . gamma - ray bursts observed with watch - eureca . in : fishman g.j . , brainerd j.j . and hurley k. ( eds . ) . proc . 307 . gamma - ray bursts 2nd huntsville workshop . american institute of physics , new york , p. 13 . briggs , m.s . , pendleton , g.n . , brainerd , j.j . , connaughton , v. , kippen , r.m . , meegan , c.a . , hurley , k. 1998 . batse grb locations errors . in : meegan c. , preece r. , and koshut t. ( eds . ) . 4th huntsville grb symposium , in press . astro - ph 9712079 . castro - tirado , a.j . , brandt , s. , lund , n.,lapshov , i.y . , terekhov , o. , sunyaev , r.a . , watch observations of gamma - ray bursts during 1990 - 1992 . in : fishman g.j . , brainerd j. j. , and hurley k. ( eds . ) . proc . 307 . gamma - ray bursts 2nd huntsville workshop . american institute of physics , new york , p. 17 . gorosabel , j. , and castro - tirado , a.j . are gamma - ray bursts related to active galactic nuclei ? . in : dermer c.d . , strickman m.s , and kurfess j.d . ( eds . ) . 4th compton symposium . american institute of physics , new york , p. 1333 . gorosabel , j. , and castro - tirado , a.j . study of the possible connection between gamma - ray bursts and active galactic nuclei . in : meegan c. , preece r. and koshut t. ( eds . ) . 4th huntsville grb symposium , in press . hakkila , j. , meegan , c.a . , pendelton , g.n . , briggs , m.s . , horack , j.m . , hartmann , d.h . , connaughton , v. 1998 . grb repetition limits from current batse observations . in : meegan c. , preece r. , and koshut t. ( eds . ) . 4th huntsville grb symposium , in press . astro - ph/9712092 .

this study is the first known attempt to search for gamma - ray burst repeaters combining data from gamma - ray experiments flying on board different satellites and making use of information derived from the bursts detected simultaneously by all the experiments . the proposed method is suitable to correlate grb data provided by experiments that overlap partially or totally in time . as an application of this method we have correlated the positions of 57 gamma - ray bursts observed by watch / granat and watch / eureca with 1905 bursts detected by batse . comparing the so - called `` added correlation '' between the watch and batse bursts with that obtained with simulated watch catalogues , we conclude that there is no indication of recurrent activity of watch bursts in the batse sample . we derive an upper limit of @xmath0 , with a confidence level of @xmath1 , for the number of watch gamma - ray bursts that could represent a population of repeaters in the batse sample .

MEXICO CITY (Reuters) - A Mexican drug lord who had been reported dead more than three years ago was likely killed in a shootout with federal forces in western Mexico early on Sunday, a government official said. Nazario Moreno, a leader of a powerful criminal gang that has ravaged the western state of Michoacan, was reported killed by the government in a firefight in December 2010. But his body was never recovered and he was widely believed to be alive. Authorities were checking on reports that Moreno was shot dead early on Sunday during a gunfight in Michoacan, said the official, who spoke on condition of anonymity. “Everything suggests, to a degree of certainty of around 98 percent, that it is this man (Moreno),” the official said. If confirmed, the death of Moreno would be another victory for President Enrique Pena Nieto’s government in its campaign to bring Mexico’s powerful drug gangs to heel. The country’s most wanted drug baron, Joaquin “Shorty” Guzman, was captured last month. A government security spokesman said there was an exchange of fire between federal forces and suspected criminals but could not confirm Moreno had been killed. A spokeswoman for the state government of Michoacan also said there was no confirmation yet. Moreno was a leader of a drug cartel known as La Familia, which fractured after his reported demise. Moreno’s allies formed the most powerful faction of La Familia, and renamed themselves the Knights Templar after a medieval military order. The Knights Templar had much of Michoacan under its control until local vigilante groups rose up against them at the start of this year and began to overrun the gang’s strongholds. The government has formed an uneasy alliance with the vigilantes despite concerns that the so-called self-defense groups had themselves been infiltrated by organized crime. A number of officials in Michoacan told Reuters earlier this year that Moreno survived the 2010 shootout and continued to play a part in the activities of the Knights Templar. A few days ago a top government official was asked about whether Moreno was dead or alive. “Proof that he is alive? Let me put it this way, there’s no proof that he is dead,” the official said, speaking on condition of anonymity. RELIGIOUS CARTEL Alfredo Castillo, the federal government’s special commissioner for Michoacan, said this month the capture of a man believed to be a son of Knights Templar leader Servando Gomez had provided valuable intelligence to the authorities. That information may have helped them track down Moreno. Moreno was born in 1970 in an unruly part of Michoacan known as the Tierra Caliente (Hot Country), where traffickers have long grown marijuana and poppies to make opium. Working as a laborer in the United States in the 1980s, Moreno converted to evangelical Christianity and when he returned home, he spread his version of the gospel within the drug trade. In 2006, Moreno named his cartel “La Familia Michoacana” and in adverts printed in newspapers claimed his troops were good Christians who defended their kind even if they smuggled drugs. La Familia was given a boost by the rising crystal meth trade, with smugglers bringing in precursor chemicals to Michoacan’s Pacific port of Lazaro Cardenas. The Knights Templar took a firm hold on Lazaro Cardenas and would go on to export iron ore from the port to China. Federal police caught up with Moreno in 2010, when he was handing out Christmas presents of washing machines and cars in a festival in the village of El Alcalde. Police who took part in the strike against Moreno said the 2,000 officers involved in the attack ran into hundreds of gunmen who blocked roads with burning cars and trucks. In hours of fighting, five officers were killed, and police shot dead more than 50 gunmen, police said. The cartel carried many of those hit, including Moreno, into the hills. ||||| MEXICO CITY (AP) — Mexican government officials are trying to determine if a man killed Sunday in an early morning shootout in western Mexico was a leader of the Knights Templar Cartel who had been reported dead in 2010. FILE - In this Dec. 12, 2010 file photo, a man holds a sign that reads in Spanish "Nazario will always live in our hearts," referring to La Familia drug cartel leader Nazario Moreno Gonzalez during a... (Associated Press) The officials tell The Associated Press that forensic teams are trying to determine his identity, but they believe it is Nazario Moreno Gonzalez. They spoke on condition of anonymity because they are not authorized to talk about the investigation. If true, it would be one of the more bizarre twists in Mexico's assault on drug cartels, in which two of the most powerful capos have been captured in the last year without a shot fired. Moreno, nicknamed "The Craziest One," would have turned 44 Saturday, according to a government birthdate. He led the La Familia cartel when he supposedly perished in a two-day gunbattle with federal police in December 2010 in his home state of Michoacan. No corpse was found, but the government of then-President Felipe Calderon officially declared him dead, saying it had proof. Some residents of Michoacan, however, reported seeing Moreno as his former cartel, La Familia Michoacana, was morphing into the more vicious and powerful Knights Templar. The cartel under both names preached Moreno's quasi-religious doctrine and moral code, even as it became a major trafficker of methamphetamine to the U.S. and ruled much of Michoacan through stealing, killing and extortion. When federal Attorney General Jesus Murillo Karam was recently asked about the rumor that Moreno was still alive, he said: "We can't confirm or deny it officially as long as we have no concrete evidence, and I can tell you that we have nothing." After his earlier reported death, Moreno reportedly helped build himself up as folk hero, erecting shrines to himself and to the Knights Templar, which adopted the Maltese cross as a symbol. The hunt for him spiked last year as vigilantes, tired of the cartel's control of the state and government inaction, took up arms against the Knights Templar, saying they wanted to get the cartel kingpins. All of the self-defense group leaders said Moreno was alive. If true, his killing would come on the heels of the Feb. 22 capture of Mexico's most powerful drug lord, Joaquin "El Chapo" Guzman, who surrendered in the Pacific resort city of Mazatlan after 13 years on the lam. The other top capo, Zetas chief Miguel Angel Trevino, was captured last summer. All three operations were carried out by elite forces of the Mexican Navy. Though Guzman's capture leaked to the press, Mexican authorities waited several hours before announcing it so that they could solidly confirm the identity of the leader of Sinaloa cartel, Mexico's largest. They later gave a detailed explanation of how they fingerprinted him and measured his facial features against photographs, as well as analyzing genetic markers from a DNA swab.

– Mexican officials say they killed a Mexican drug kingpin three years after the government supposedly killed him the first time, Reuters reports. Nazario Moreno was leader of the drug cartel La Familia when officials said he died in a two-day gunfight with government agents—but as his cartel morphed into the more powerful Knights Templar, rumors circulated that Moreno was alive. "We can't confirm or deny it officially as long as we have no concrete evidence, and I can tell you that we have nothing," said Attorney General Jesus Murillo Karam, the AP reports. Yet signs were there: The vicious Knights Templar continued the moral code and semi-religious doctrine of La Familia, and residents of the western state of Michoacan claimed to see Moreno around. Now officials say that Moreno, nicknamed "The Crazy One," has died in a firefight with the government at age 44, though forensic evidence is yet to confirm his identity. If true, Moreno's killing wraps up a strange year in which two Mexican drug kingpins—Joaquin "El Chapo" Guzman and Zetas chief Miguel Angel Trevino—were taken without a shot fired.

SECTION 1. SHORT TITLE. This Act may be cited as the ``Parental Right to Decide Protection Act''. SEC. 2. FINDINGS. The Congress finds as follows: (1) HPV, the human papillomavirus, is the most common sexually transmitted infection in the United States. HPV types 16 and 18 cause about 70 percent of cervical cancers. The Centers for Disease Control and Prevention estimates that about 6,200,000 Americans become infected with HPV each year and that over half of all sexually active men and women become infected at some time in their lives. On average, there are 9,710 new cases of cervical cancer and 3,700 deaths attributed to it in the United States each year. (2) Early detection is the key to diagnosing and curing cervical cancer, and therefore the Food and Drug Administration (FDA) recommends that all women get regular Pap tests. The Pap test looks for cell changes caused by HPV, so the cervix can be treated before the cells turn into cancer. The FDA also states the Pap test can also find cancer in its early stages so it can be treated before it becomes too serious, and reaches the conclusion that it is rare to die from cervical cancer if the disease is caught early. (3) On June 8, 2006, the FDA approved Gardasil, the first vaccine developed to prevent cervical cancer, precancerous genital lesions, and genital warts due to human papillomavirus (HPV) types 6, 11, 16, and 18. Gardasil is a recombinant vaccine, it does not contain a live virus, and it is given as three injections over a six-month period. The vaccine is approved for use in females 9-26 years of age. However, the FDA also states that since the vaccine is new, more studies need to be done to determine how long women will be protected from HPV. For example, the FDA does not know if a booster is needed after a couple of years to ensure continuity of protection. (4) As detailed by the FDA, four studies were conducted in 21,000 women, one in the United States and three multinational, to show how well Gardasil worked in women between the ages of 16 and 26. The study period was not long enough for cervical cancer to develop; however, preventing cervical precancerous lesions is believed highly likely to result in the prevention of cervical cancer. (5) In January 2007 the Advisory Committee on Immunization Practices (ACIP), under the Centers for Disease Control and Prevention, issued changes to the previous childhood and adolescent immunization schedule. The ACIP recommends the new human papillomavirus vaccine (HPV) to be administered in a 3- dose schedule with the second and third doses administered 2 and 6 months after the first dose. Routine vaccination with HPV is recommended for females aged 11-12 years, the vaccination series can be started in females as young as age 9 years, and a catch up vaccination is recommended for females aged 13-26 years who have not been vaccinated previously or who have not completed the full vaccine series. (6) In July 2008 Judicial Watch, a Washington-based public interest group, reported that there have been close to 9,000 health complaints as a result of Gardasil. These complaints have surfaced because Gardasil recipients have experienced everything from massive wart outbreaks to paralysis, and even death in 18 cases. (7) States historically have maintained the practice of applying immunization recommendations to their school admittance policies so as to protect schoolchildren from outbreaks of contagious disease. The Association of American Physicians and Surgeons states that there is no public health purpose for mandating HPV vaccine for schoolchildren. HPV is a sexually transmitted disease. (8) With a number of states entertaining legislation which takes the unprecedented step in requiring young girls to obtain a vaccine for a disease that is not spread by casual contact in order to attend school, many organizations and associations have come out against mandatory HPV vaccine programs. (9) The American College of Pediatricians and the Association of American Physicians and Surgeons are opposed to any legislation which would require HPV vaccination for school attendance. They have stated that excluding children from school for refusal to be vaccinated for a disease spread only by intercourse is a serious, precedent-setting action that trespasses on the right of parents to make medical decisions for their children as well as on the rights of the children to attend school. (10) Federal funds should not be used to implement a mandatory vaccine program for a disease that does not threaten the public health of schoolchildren in the course of casual, daily interaction between classmates and inserts the government into the lives of children, parents, and physicians. SEC. 3. PROHIBITION AGAINST FUNDING FOR MANDATORY HUMAN PAPILLOMAVIRUS (HPV) VACCINATION PROGRAMS. No Federal funds or other assistance may be made available to any State or political subdivision of a State to establish or implement any requirement that individuals receive vaccination for human papillomavirus (HPV).

Parental Right to Decide Protection Act - Prohibits federal funds or other assistance from being made available to any state or political subdivision to establish or implement any requirement that individuals receive vaccination for human papillomavirus (HPV).

the spectroscopic studies to determine form factors of the @xmath15 semi - leptonic decays , @xmath16 ( @xmath17 ) , are of importance both in studying low energy properties of the strong interaction in terms of effective theories @xcite , and also in studying fundamental interactions . in our previous work @xcite , we reported a result testing the exotic couplings in @xmath2 ( @xmath3 ) decay , showing the non existence of scalar and tensor interactions , contradicting the current world average adopted by particle data group @xcite . in the present work , the @xmath0 ( @xmath1 ) events , which were collected simultaneously , were analyzed to determine the ratio of the @xmath1 and @xmath3 decay widths @xmath6 . this quantity is one of the most important observables to evaluate the @xmath13 form factors . assuming that only the v@xmath18a interaction contributes to the @xmath19 decay , the decay amplitude can be described by two dimensionless form factors , @xmath20 and @xmath21 , which are functions of the momentum transfered to the leptons @xmath22=@xmath23 where @xmath24 and @xmath25 are the four momenta of the @xmath26 and @xmath27 , respectively . they are given as , @xmath28 , \nonumber \\ f_{0}(q^{2})&=&f_{0}(0)[1+\lambda_{0}(q / m_{\pi})^{2 } ] . \nonumber\end{aligned}\ ] ] assuming @xmath11-@xmath12 universality , the form factors between @xmath29 and @xmath30 decays are identical and @xmath6 can be written as @xcite , @xmath31 this equation can not determine the @xmath32 and @xmath10 parameters uniquely but simply fixes a relationship between them . however , if the @xmath32 value derived from @xmath30 data analyses is assumed , the @xmath10 parameter can be obtained from eq . ( [ kihon1 ] ) . in this analysis , our @xmath30 result for the @xmath32 parameter , @xmath33 , was employed @xcite . it should be noted that the @xmath10 parameter can be also determined by studying the dalitz plot distribution of @xmath29 decay or the muon polarization in @xmath29 decay @xcite . the determination of the @xmath10 parameter from the @xmath4 ratio is based on the assumption of @xmath11-@xmath12 universality . this is not the case for the other two methods . thus , @xmath11-@xmath12 universality in @xmath19 decay can be tested by comparing the @xmath10 parameter obtained from a branching ratio measurement @xmath34 with that obtained from a dalitz plot measurement @xmath35 and/or @xmath36 polarization measurement @xmath37 . in this case , however , a precise acceptance function has to be carefully determined over the whole dalitz space for the @xmath29 dalitz plot analysis . in this letter , we present a new precise measurement of the @xmath4 branching ratio and the @xmath10 parameter . the experiment used a stopped @xmath15 beam in conjunction with a 12-sector iron - core superconducting toroidal spectrometer @xcite . @xmath4 was obtained by measuring the ratio of the number of accepted @xmath38 and @xmath30 events corrected for detector acceptance . the experiment was performed at the kek 12 gev proton synchrotron . the experimental apparatus was constructed for a t - violation search in @xmath38 decay @xcite . a schematic cross sectional side view of the detector is shown in fig . [ fg : side ] . we detected both of the @xmath39 decay gammas which enabled us to reconstruct the complete kinematics of a @xmath19 event in contrast to the previous experiment @xcite ; this increased the reliability of the event selection . because of the rotational symmetry of the 12 identical gaps in the spectrometer and the large directional acceptance of the @xmath39 detector @xcite , distortions due to detector acceptance were drastically reduced . moreover , the similarity of the @xmath29 and @xmath40 kinematics reduced the systematic error due to the imperfect reproducibility of the experimental conditions in the simulation of the ratio of the calculated acceptance for the @xmath29 and @xmath40 decays . the measurement was carried out for two values of the central magnetic field strength , b=0.65 and 0.90 t , yielding a consistency check with regard to the spectrometer acceptance and energy loss estimation in the target . @xmath29 ( @xmath40 ) events were identified by analyzing the @xmath36 ( @xmath41 ) momentum with the spectrometer and detecting the two photons in the csi(tl ) calorimeter . charged particles from the target were tracked and momentum - analyzed using multi - wire proportional chambers ( mwpcs ) at the entrance ( c2 ) and exit ( c3 and c4 ) of the magnet gap , as well as by the active target and an array of ring counters @xcite surrounding the target . particle identification between the @xmath42s and @xmath41s was carried out by time - of - flight ( tof ) between tof1 and tof2 scintillation counters . tof1 surrounds the active target and tof2 is located at the exit of the spectrometer . the @xmath39 detector , an assembly of 768 csi(tl ) crystals , covers 75% of the total solid angle . since photons produce electromagnetic showers , their energy was shared among several crystals . the photon energy and hit position were obtained by summing the energy deposits and energy - weighted centroid , respectively . timing information from each module was used to identify a photon cluster and to suppress accidental backgrounds due to beam particles . the two - photon invariant mass ( @xmath43 ) and the @xmath39 energy and direction were obtained from the photon momentum vectors . @xmath38 and @xmath30 decays at rest were selected by the following procedure , which is similar to our @xmath30 study . the @xmath15 decay time , defined as the charged lepton signal at the tof1 counter , was required to be more than 5 ns later than the @xmath15 arrival time measured by the @xmath44erenkov counter to remove in - flight @xmath15 decays . events with @xmath45 decays in - flight and scattering of charged particles from the magnet pole faces were eliminated by a track consistency cut in the ring counters . events with two clusters in the csi(tl ) calorimeter were selected as @xmath39 decays and events with other cluster numbers were rejected . the acceptance cut on the invariant mass was 50@xmath46140 mev/_c_@xmath47 . requirements for the charged particle momentum corrected for the energy loss in the target ( @xmath48 175 mev/@xmath49 ) plus opening angle between a charged particle and the @xmath39 ( @xmath50 154@xmath51 ) removed the @xmath52 events . the mass squared ( @xmath53 ) of the charged particles , obtained from the tof and momentum , are shown in fig . [ fg : massgmc ] integrated over the entire momentum region . the @xmath36 and @xmath41 selection regions are also indicated in the figure . the timing resolution of @xmath54270 ps provides a good separation between the @xmath29 and @xmath40 events . it should be emphasized that only these requirements were imposed for the @xmath38 and @xmath40 event extraction . the numbers of good events after those cuts mentioned above are 12882(10704 ) and 23122(16850 ) at 0.65(0.90 ) t for @xmath29 and @xmath30 decays , respectively , where small fractions due to the background events are still included . fig . [ fg:65kl3 ] and [ fg:90kl3 ] show the @xmath55 and @xmath30 spectra for the setting of b=0.65 and 0.90 t , respectively . in order to obtain the detector acceptance and estimate the background fraction , the monte carlo simulation was carried out for both the charged particle measurement by the spectrometer and the @xmath39 measurement by the csi(tl ) detector . the initial dalitz distributions were generated with the values of @xmath56 and the current world average @xmath57 , while the dalitz distribution of @xmath30 decay is insensitive to the @xmath58 parameter . the radiative corrections were taken into account by following the ginsberg procedure @xcite . the simulation data were analyzed in the same manner as the experimental sample . the dotted lines in fig . [ fg:65kl3 ] and fig . [ fg:90kl3 ] show the simulation spectra for the setting of b=0.65 and 0.90 t , respectively , using the assumed @xmath32 and @xmath10 parameters . these spectra are normalized so that the total number of events is the same as the experimental one . here , it is to be noted that much higher statistical accuracy for the monte carlo simulation is necessary to determine the form factors from the @xmath38 dalitz plot analysis . by using the simulation data , the detector acceptance ( @xmath59 ) is calculated as , @xmath60 where @xmath61 and @xmath62 are the number of events accepted by our event selection requirements and the number of generated @xmath15 events , respectively . @xmath63 denotes the detector acceptance at the assumed form factor for the production of the simulation samples . they were @xmath64 , @xmath65 for the setting of b=0.65 t and @xmath66 , @xmath67 for the setting of b=0.90 t. the detector acceptance depends only slightly on the form factor ( @xmath68 , the shape of the dalitz distribution ) , therefore a correction factor @xmath69 is introduced . @xmath70 was calculated by taking into account the event selection requirements such as @xmath71 , @xmath72 , and @xmath73 cuts . as shown in fig . [ fg : lacc](a , b ) , the @xmath70 distribution for @xmath38 decay was obtained as a contour plot in the ( @xmath74,@xmath58 ) space , while @xmath70 for @xmath30 decay was obtained as a function of the @xmath32 parameter . @xmath53 spectra were calculated by assuming a tof resolution of @xmath75=270 ps . they are shown as dotted lines in fig . [ fg : massgmc ] . since the charged particles were identified by @xmath53 measurement , the choice of the tof response function was important for the determination of the background contamination . we took into account @xmath52 , @xmath30 , @xmath76 decays for the @xmath29 background and @xmath52 , @xmath29 , @xmath77 decays for the @xmath30 background . the background fraction depends on the magnetic setting of the spectrometer , as summarized in table [ tb : bgke3 ] . the most dominant background is due to @xmath52 decay in - flight . the accidental background fraction due to beam particles was estimated to be 0.3% for both @xmath38 and @xmath30 samples . .background fractions included in the @xmath38 and @xmath30 samples . [ cols="^ , < , > , > " , ] the ratio of the @xmath0 ( @xmath1 ) and @xmath2 ( @xmath3 ) decay widths , @xmath4 , has been measured for stopped positive kaons . assuming @xmath11-@xmath12 universality in @xmath13 decay , the coefficient of the @xmath8 dependent term of the @xmath9 form factor was determined from the measured @xmath4 ratio . in contrast to the previous experiments , a large detector acceptance and its symmetrical structure enabled us to reduce the statistical errors while suppressing the systematic errors . our results are + @xmath78 the @xmath10 parameter obtained from the present work is consistent with that from recent @xmath14 dalitz plot analyses @xcite , which supports the validity of @xmath11-@xmath12 universality in @xmath13 decay . if the assumption of @xmath11-@xmath12 universality is removed , @xmath6 can be written as @xcite , @xmath79 ^ 2 \nonumber \\ & \times&(0.6457 + 2.2342\lambda_+^{\mu}-2.3873\lambda_+^{e}+1.5646\lambda_0 ) , \label{eqnot } \end{aligned}\ ] ] where @xmath80 is weak coupling constant for the lepton current . substituting + @xmath81 ( present result with no @xmath11-@xmath12 universality assumption ) , @xmath82 ( the current world average ) , @xmath83 ( our @xmath30 result ) , and @xmath84 ( error weighted average of ref . @xcite and @xcite ) into eq . ( [ eqnot ] ) , @xmath85 is derived to be @xmath86 which is consistent with unity within the experimental error . from the viewpoint of the theoretical framework , the @xmath13 form factors are of importance in studying low energy properties of the strong interaction in terms of effective theories . the predicted values of the @xmath10 parameter are @xmath87 @xcite and @xmath88 @xcite . the present result is consistent with the former and inconsistent with the latter . also , the @xmath891/2 rule leads to identical @xmath10 parameters between @xmath13 and @xmath90 decays @xcite . the @xmath10 parameter from the @xmath90 analyses has been determined to be @xmath91 @xcite , which is consistent with the present result . this work has been supported in japan by a grant - in - aid from the ministry of education , science , sports and culture , and by jsps ; in russia by the ministry of science and technology , and by the russian foundation for basic research ; in canada by nserc and ipp , and by the triumf infrastructure support provided under its nrc contribution ; in korea by bsri - moe and kosef ; in the u.s.a by nsf and doe ; and in taiwan by nsc . the authors gratefully acknowledge the excellent support received from the kek staff . 00 j. gasser and h. leutwyler , nucl . phys . * b250 * , 517 ( 1985 ) . kazakov , v.n . pervushin , and m.k . volkov , phys . b64 * , 201 ( 1976 ) . s. shimizu _ et al . _ , phys . lett . * b495 * , 33 ( 2000 ) . particle data group , eur . j. * c15 * , review of particle physics ( 2000 ) . fearing , e. fischbach , and j. smith , phys . d2 * , 542 ( 1970 ) ; phys . * 24 * , 189 ( 1970 ) . j. imazato _ et al . _ , in _ proceedings of the 11th international conference on magnet technology _ ( elsevier applied science , london , 1990 ) , p.366 . et al . _ , . lett . * 83 * , 4253 ( 1999 ) . j. heintze _ _ , phys . lett . * b70 * , 482 ( 1977 ) . d.v . dementyev _ et al . _ , nucl . instr . method * a440 * , 151 ( 2000 ) . a.p . ivashkin _ et al . _ , nucl . instr . method * a394 * , 321 ( 1997 ) . ginsberg , phys . rev . * 42 * , 1035 ( 1966 ) . l.b . et al . _ , phys . rev . * 155 * , 1505 ( 1967 ) . r. whitman _ et al . _ , phys . rev . * d21 * , 652 ( 1980 ) . v.m . artemov _ _ , physics of atomic and nuclei . * 60 * 2023 ( 1997 )

the ratio of the @xmath0 ( @xmath1 ) and @xmath2 ( @xmath3 ) decay widths , @xmath4 , has been measured with stopped positive kaons . @xmath1 and @xmath3 samples containing 2.4@xmath5 and 4.0@xmath5 events , respectively , were analyzed . the @xmath6 ratio was obtained to be [email protected](stat.)@xmath70.008(syst . ) calculating the detector acceptance by a monte carlo simulation . the coefficient of the @xmath8 dependent term of the @xmath9 form factor was also determined to be @[email protected](stat.)@xmath70.004(syst . ) with the assumption of @xmath11-@xmath12 universality in @xmath13 decay . the agreement of our result with the @xmath10 value obtained from @xmath14 dalitz plot analyses supports the validity of the @xmath11-@xmath12 universality . , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , and

the loss of coherence of a quantum two - level system ( quantum bit ) is caused by its unavoidable coupling to the surrounding environment . for solid - state qubits , the decoherence process can be quite fast due to coupling to a large number of internal degrees of freedom . our understanding of quantum decoherence and methods for its suppression in a realistic solid - state environment is mainly confined to the cases of a qubit interacting with bosonic@xcite and nuclear spin baths,@xcite the so - called ( and extensively studied ) spin - boson and spin - bath models , respectively . a less well understood , but very relevant case for solid - state quantum architectures is that of a qubit coupled to a fermionic bath,@xcite which dramatically differs from the previous examples . in this paper we study quantum decoherence in the context of a superconducting charge qubit@xcite interacting with the non - trivial bath of andreev fluctuators.@xcite this problem is a paradigmatic spin - fermion decoherence problem and applies to many situations involving the quantum coupling of a qubit ( `` spin '' ) to a general fermionic environment . using a many - body keldysh path integral approach,@xcite we obtain a quantum - mechanical description of the qubit evolution under pulse sequences aimed at prolonging the coherence of the system . the simplest case of decoherence under pulses is the spin echo dephasing experiment , which has been shown to extend the coherence time of solid state ( superconducting ) qubits,@xcite by essentially eliminating the quasi - static shifts of qubit energy splitting ( inhomogeneous broadening ) due to the slow environmental fluctuations . however , sequences involving more pulses , for example , cpmg @xcite and uhrig s @xcite sequences , are expected to lead to a further increase of the coherence time.@xcite in this paper , we consider an experimentally relevant example - a superconducting qubit coupled to fluctuating background charges,@xcite e.g. electrons residing on anderson - impurity sites . due to a large on - site coulomb repulsion forbidding double occupancy , this example represents a non - trivial interacting bath . the dynamics of the charge fluctuations on the impurity sites is determined by the hybridization of impurity levels with the quasiparticle band of the superconductor . to the lowest order in tunneling at the superconductor / insulator interface , the hybridization of the impurity levels can be described by a correlated tunneling events of two electrons with opposite spin to / from the superconductor . we show that in the small background - charge density limit , these fluctuations lead to a @xmath0 spectral density of noise . using these results , we finally obtain the quantum - mechanical description of the qubit evolution driven by external pulses , and discuss optimal strategy for the suppression of the decoherence with designed composite pulse sequences . the paper is organized as follows : in sec . [ general ] we provide a general derivation of the qubit evolution with pulses and map the calculation of decoherence function onto keldysh path integral formalism . in secs . [ andreevbath ] and [ andreevspectral ] we introduce andreev fluctuator bath and derive spectral density of noise for this model . finally , in sec . [ sec : f ] we discuss the influence of pulse sequences on the qubit decoherence . the transverse dynamics of a qubit interacting with its environment is determined by the following hamiltonian @xmath1 here the environment is represented by a fermionic bath @xmath2 , and the qubit is coupled to the environment through the density fluctuation operator : @xmath3 this model corresponds precisely to the coupling of a superconducting charge qubit to the density fluctuations on the impurities in the substrate . here @xmath4 and @xmath5 are the fermionic annihilation and creation operators at @xmath6-th site with spin @xmath7 , and @xmath8 and @xmath9 are , respectively , the strength of the coupling and average occupation of @xmath6-th impurity , i.e. @xmath10 . equations ( [ eq : h ] ) and ( [ eq : v ] ) define our spin - fermion model . we study the evolution of the qubit in contact with a fermionic bath assuming the qubit energy relaxation time @xmath11 to be much longer than the quantum dephasing time @xmath12 ( thus only @xmath13 coupling is present in the hamiltonian ) . qubit decoherence under the influence of the environment is given by the off - diagonal matrix elements of the qubit s reduced density matrix , and for the free evolution of the qubit we get ( @xmath14 ) @xmath15 in the above @xmath16 is the density matrix of the whole system ( qubit@xmath17bath ) , which is assumed factorizable at @xmath18 , @xmath19 is the trace with respect to the bath degrees of freedom , and @xmath20 is the decoherence function defined as @xmath21 with the brackets representing the thermal average with respect to the bath hamiltonian @xmath22 , i.e. @xmath23 . the time @xmath24 always refers here to the total time of the evolution . in addition to the free evolution of the qubit ( free induction decay ) , one is often interested in the dynamics of the system subject to external @xmath25-pulses@xcite which could , in principle , prolong or restore quantum coherence . the @xmath25-pulses considered here correspond to rotations of the qubit s bloch vector by angle @xmath25 about , e.g. , the @xmath26 axis , and are short enough for the bath dynamics during the pulse duration to be negligible . then , the evolution operator for qubit and bath is given by @xmath27 with @xmath28 and @xmath29 being the number of applied pulses and time delays between the pulses , respectively , and the total evolution time @xmath30 . one can see that the well - known hahn spin echo ( se ) sequence , for example , corresponds to a single pulse with @xmath31 . using the fact that in the `` pure dephasing '' case under consideration , the qubit states @xmath32 are the eigenstates of the hamiltonian ( [ eq : h ] ) , we can write the decoherence function under the influence of pulses as @xmath33 with the evolution operators @xmath34 given by @xmath35 where @xmath36 is the parity of the sequence . then , the off - diagonal elements of the qubit density matrix are given by @xmath37 here the phase factor is zero for all balanced sequences ( for which the total times of evolution due to @xmath38 and @xmath39 are the same in eq . ( [ eq : upm ] ) ) . the evolution of the qubit under se sequence , for example , acquires a simple form @xmath40 with @xmath41 . decoherence under pulses has been analyzed with methods specific to the spin - boson model@xcite and the spin bath model,@xcite or using operator algebra.@xcite the latter approach , although very general , does not allow for transparent understanding of physics of the bath . however , the evaluation of @xmath42 defined in eq . ( [ eq : wn ] ) can be mapped onto the evolution on the keldysh contour,@xcite putting the calculation of decoherence into the framework of many - body theory . similar formalism has been used to study full counting statistics of a general quantum mechanical variable and has proved to be quite convenient.@xcite the evolution operators @xmath43 can be written as @xmath44 \,\ , , \ ] ] where @xmath45 is the time ordering operator . the function @xmath46 encodes a particular sequence , and is defined as @xmath47 where @xmath48 is the heaviside step function , @xmath49 with @xmath50 are the times at which the pulses are applied , @xmath51 , and @xmath52 . thus , the product of operators inside the average in eq . ( [ eq : wn ] ) corresponds to ( reading from left to right ) the time - ordered evolution from @xmath53 to @xmath24 ( with @xmath54 coupling ) , followed by the time anti - ordered evolution from @xmath24 to @xmath53 ( with @xmath55 coupling ) . we can then introduce the keldysh contour @xmath56 ( see fig . [ fig : contour]a ) together with the notion of contour - ordering of operators.@xcite the qubit - bath coupling takes then two opposite signs on the upper / lower branch of the contour : @xmath57 . while @xmath46 is non - zero only for @xmath58 $ ] , we can extend the limits of time integration on both branches to @xmath59 $ ] . the evolution from @xmath60 allows one to include the adiabatically turned - on interactions in @xmath61 ( see , for example , ref . [ ] ) , paving the way to the treatment of decoherence in an interacting fermionic bath . the final result is most compactly written as a functional integral with the grassmann fields @xmath62 and @xmath63 defined on the keldysh contour:@xcite @xmath64\ ! \right ) \ ! \right \rangle\!\!=\!\ ! \frac{1}{z_b}\!\int \!\!\ ! \mathcal{d}\bar{\psi}_l\mathcal{d}\psi_l \exp \!\ ! \left ( \!\ ! i s_b\!\left[\bar{\psi } , \psi\right]\!-\!i\!\int\limits_{c}dt'\ ! \sum\limits_{l\sigma } \!v_l(t')\!f_{n } ( t')\!\!\left[\bar{\psi}_{l\sigma}(t')\psi_{l\sigma}(t')\!-\!\langle n_{l\sigma}\rangle\!\right ] \!\ ! \right)\!\ ! , \label{funcint}\end{aligned}\ ] ] where the integration is performed on the contour @xmath56 shown in fig . [ fig : contour]a , @xmath65 on the upper / lower branch of the contour , and the normalization constant is defined as the functional integral with @xmath66 . the bath action @xmath67 , and the functional integration with non - interacting @xmath68 corresponds to averaging over an equilibrium noninteracting density matrix at @xmath69 . this formulation of the decoherence problem enables one to use techniques and approximations developed in many - body theory . it also allows for a transparent treatment of the physics of the bath while simply encoding the driving of the qubit in a single function of time @xmath46 . -th impurity with energy below the gap @xmath70 tunnels into superconductor , propagates over distances of the order of coherence length @xmath71 and recombines with another electron with opposite spin from @xmath72-th site into a cooper - pair . the amplitude for such andreev process decays exponentially with distance between the impurity sites @xmath73 , see eq . ( [ eqn : amplitude ] ) . ] in order to evaluate the functional integral ( [ funcint ] ) , one needs to specify the bath hamiltonian . here , as an example , we consider a non - trivial bath of andreev fluctuators,@xcite which describes the fluctuations of the occupation of impurities close to insulator / superconductor interface due to andreev processes . this model takes into account coherent processes of creation ( destruction ) of the cooper pair in the superconductor by correlated tunneling of two electrons from ( to ) different impurity sites in the insulator,@xcite see also fig . [ fig : tunneling ] . in the limit when the superconducting gap energy @xmath70 is the largest relevant energy scale in the problem ( @xmath74 ) , the effective hamiltonian for the andreev fluctuator bath , after integrating out superconducting degrees of freedom , is given by @xmath75\!\!.\end{aligned}\ ] ] here , @xmath76 and @xmath77 are the energy of a localized electron on @xmath6-th impurity ( measured with respect to the fermi energy @xmath78 of the conduction electrons ) and repulsive on - site interaction ( assumed to be large enough to prevent double occupation of the sites ) , respectively . the matrix elements @xmath79 , in the limit of low transparency barrier between the insulator and superconductor , are given by @xmath80 here @xmath81 is the fermi momentum , @xmath71 is the coherence length in a clean superconductor . the amplitude @xmath82 is determined by the tunneling matrix element between the insulator and superconductor @xmath83 , the normal density of states in the metal @xmath84 , the localization length under the barrier @xmath85 and the size of the impurity wavefunction @xmath86.@xcite on time along the keldysh contour . b ) the plot of the function @xmath87 for the spin echo sequence ( @xmath88 ) . ] given the hamiltonian ( [ eqn : hb ] ) , the action for the bath on the keldysh contour can be written as @xmath89&\!\!=\!\!\sum_{lj}\int \limits_{c}dt ' \sum_{\sigma } \delta_{lj } \bar{\psi}_{l\sigma}(t')(i\partial_{t'}\!-\!\varepsilon_{l}\!-\!u \langle n_{l,-\sigma}\rangle)\psi_{l\sigma}(t ' ) \nonumber\\ & \!+\ ! a^*_{lj}\bar{\psi}_{l\uparrow}(t ' ) \bar{\psi}_{j\downarrow}(t')+a_{lj } \psi_{j\downarrow}(t')\psi_{l\uparrow}(t ' ) \,\ , .\end{aligned}\ ] ] here we used the mean - field approximation for the anderson impurity model assuming that the kondo temperature @xmath90 is smaller than the superconducting gap @xmath70 , which is reasonable in the situation at hand when the impurities are located in the substrate and the tunneling matrix element @xmath91 coupling them to the states in the superconductor is small . the occupation probabilities @xmath9 are obtained self - consistently using @xmath92,\end{aligned}\ ] ] see ref . [ ] for more details . performing a keldysh rotation,@xcite one can calculate the full green s function @xmath93 for the bath ( see fig . [ fig : dyson_eq ] ) @xmath94 here @xmath95 is the bare green s function , see eq . ( [ eqn : sb ] ) , and the self energy @xmath96 is calculated to second order in @xmath97 giving the components of the self - energy matrix @xmath98 in eqs . ( [ eqn : sigma_a ] ) and ( [ eqn : sigma_k ] ) we have neglected the off - diagonal terms in the impurity indices , i.e. @xmath99 . since the amplitude @xmath79 oscillates on the length scale of @xmath100 , the contribution of these off - diagonal terms to the self - energy is small . in the born approximation . here we have adopted the convention of ref . [ ] . the advanced and keldysh green s functions are obtained analogously resulting in eqs . ( [ eqn : sigma_a])-([eqn : sigma_k ] ) . ] using the above results , the action for the bath can be written in terms of the full green s function @xmath93 . then , the decoherence function becomes @xmath101\!=\!\frac{1}{z_b}\!\int \mathcal{d}\bar{\psi}\mathcal{d}\psi \\ & \times \exp\!\left[i \sum_{l\sigma } \int \limits_{-\infty}^{\infty } dt_1 \!\ ! \int \limits_{-\infty}^{\infty } dt_2 \left ( \sum_{a , b=1}^{2 } \bar{\psi}_{l\sigma}^{(a)}(t_1 ) \left [ { \bf \hat{g}}^{-1}_{ll\sigma}(t_1,t_2 ) \right]_{ab } \psi^{(b)}_{l\sigma}(t_2)\!-\!2\delta(t_1\!-\!t_2)v_l f^{(n)}(t_1)\left [ \rho_{l\sigma}(t_1)\!-\ ! \langle n_{l\sigma } \rangle \right]\right ) \right].\nonumber\end{aligned}\ ] ] here , @xmath102 corresponds to the fermion density operator @xmath103\ ! $ ] ; the fields @xmath104 and @xmath105 are given by the appropriate superposition of the fermionic fields on the upper and lower parts of the keldysh contour , see ref . after performing the functional integral over the fermionic fields and expanding to second order in @xmath8 , one finds @xmath106\!\!. \label{chi1}\end{aligned}\ ] ] equation ( [ chi1 ] ) holds whenever the short - time expansion is valid . the long - time asymptote can be obtained by resumming the whole series.@xcite by introducing the fourier transform of the green s functions , eq . ( [ chi1 ] ) can be formally recast as @xmath107 here @xmath108 is a sequence - specific filter function , the role of which we discuss in sec . [ sec : f ] . thus , to second order in @xmath109 we obtain @xmath110 having the same structure as in the case of a qubit coupled to the spin - boson bath or classical noise,@xcite i.e. @xmath110 is the integral of the product of the environment - specific spectral density of noise @xmath111 and sequence - specific filter function @xmath112 . the spectral density of quantum noise @xmath113 in the spin - fermion problem is given by @xmath114\!. \end{aligned}\ ] ] in the frequency domain , the full green s functions are @xmath115,\end{aligned}\ ] ] where the self energy @xmath116 is defined as @xmath117 equation ( [ eqn : noise ] ) , defining the noise spectral density in the quantum - mechanical many - body language enables a direct calculation of decoherence in various situations , as we consider next . in general , the solution for @xmath113 with many andreev fluctuators , can be obtained numerically by randomly generating the energies @xmath76 , and positions @xmath118 of the impurities at the insulator / superconductor interface . the numerically obtained spectral density of noise @xmath113 for 50 fluctuators is shown in fig . [ fig : noise_lowt_andreev ] . at low frequencies the noise power spectrum has @xmath0 dependence . for andreev fluctuator model . the plot is obtained by randomly generating the positions @xmath119\xi$ ] and energies @xmath120$]k of 50 impurity sites and then , numerically integrating eq . ( [ eqn : noise ] ) . here we assumed that @xmath121 , on - site repulsion @xmath122 , and the sites are occupied with equal number of electrons with spins up and down . we used @xmath123 , @xmath124k and @xmath125k . the dashed ( blue ) and dot - dashed ( black ) lines , shown for comparison , correspond to @xmath0 and @xmath126 noise spectra . ] for @xmath127 and @xmath128 much smaller than the typical impurity level spacing @xmath129 and temperature @xmath130 , the analytical solution for the spectral density of noise ( [ eqn : noise ] ) is given by @xmath131\frac{\gamma_{l\sigma}(\tilde{\varepsilon}_{l\sigma})}{\omega^2 + 4\gamma_{l\sigma}(\tilde{\varepsilon}_{l\sigma})^2},\end{aligned}\ ] ] where @xmath132 , and @xmath133 is the broadening of the impurity energy levels due to andreev processes . this broadening corresponds to the fluctuations of the impurity occupations changing the electrostatic environment of the qubit , and thus causing dephasing . from eq . ( [ eqn : noise_small ] ) , one can see that @xmath113 is given by a sum of lorentzians with different widths , which under proper distribution of @xmath134 gives rise to a @xmath0 noise spectrum ( see below ) . given that the charge density fluctuations via andreev processes involve two impurities with energies of the order of @xmath130 , the probability to find two such impurities is proportional to @xmath135 with @xmath136 being the impurity energy bandwidth , and thus , @xmath137 at low frequencies as seen experimentally.@xcite for @xmath0 spectrum to arise from eq . ( [ eqn : noise_small ] ) , the distribution of @xmath138 has to be log - normal . in order to have such distribution , the density of the charge traps has to be small , so that the dominant contribution to the self energy in eq . ( [ sigma_freq ] ) comes from few pairs of impurity sites , which are selected from the sum because of the energy conservation and distance constraint . then , the switching rate @xmath139 for a certain @xmath72 ( see eq . ( [ eqn : amplitude ] ) ) . since the distances between the charge traps are uniformly distributed , the probability of finding a switching rate @xmath140 is @xmath141 , leading to @xmath0 noise . in the opposite limit of large density of charge traps , many sites @xmath72 contribute to the sum in eq . ( [ sigma_freq ] ) , and the switching rates @xmath138 self average and become approximately the same for all sites . note that unlike in the theory of @xmath0 charge noise produced by fluctuating two level systems ( tls ) in the substrate with log - uniform distribution in the tunnel splitting,@xcite the emergence of the @xmath0 noise within andreev fluctuator model has a qualitatively different geometrical origin due to the exponential dependence of the rate @xmath134 on the distance between different impurity sites . this finding of the geometric origin of the @xmath0 noise in the andreev fluctuator model is an important result of our work . we note that the model of charge traps with no on - site repulsion @xmath142 [ ] does not lead to @xmath0 noise because in this case the self - energy is dominated by the two - electron tunneling from the same site . the contributions to the self energy from andreev processes involving other sites are exponentially smaller than the dominant term , and the distribution of the rates in eq . ( [ eqn : noise_small ] ) is not log - normal . therefore , we emphasize that the realistic model for @xmath0 noise due to andreev processes should include both spinful fermions ( to correctly describe the dynamics of charge fluctuations ) , and large on - site repulsion ( to prevent double - electron occupation ) . at high frequencies @xmath143 , the spectral density @xmath113 has resonances corresponding to the virtual processes of correlated two - electron tunneling from ( to ) the impurity sites in the insulator . these resonances , describing manifestly quantum - mechanical processes , can be seen in fig . [ fig : noise_lowt_andreev ] at high frequencies . their contribution to the decoherence of the qubit is suppressed by a factor @xmath144 , see eq . ( [ eqn : chi ] ) . however , going beyond the pure dephasing model , @xmath145 , considered here , one can show that correlated two - electron tunneling processes contribute to the energy relaxation of the qubit.@xcite the time dependence of the decoherence function @xmath146 under a pulse sequence is given by eqs . ( [ funcint2])-([eqn : chi ] ) , showing that the noise contribution is modulated by a filter function @xmath112 . for the free induction decay @xmath147 $ ] , whereas for spin echo we have @xmath148 $ ] suppressing the low - frequency ( @xmath149 ) part of @xmath113 . in general , higher - order pulse sequences act as more efficient high - pass filters of environmental noise , i.e. for @xmath28 pulses applied in time @xmath24 only frequencies @xmath150 contribute to @xmath110 . due to the formal analogy between eq . ( [ eqn : chi ] ) and the solution for the decoherence under classical gaussian noise , the analysis given for the latter case in ref . [ ] also applies here as long as the time expansion is valid . the results relevant for the noise spectral density derived here can be summarized as follows . for @xmath151 , we obtain @xmath152 for all sequences applicable to the pure dephasing case , i.e. the cpmg sequence,@xcite periodic dynamical decoupling,@xcite concatenations of spin echo,@xcite and uhrig s sequence.@xcite thus , sequences beyond spin echo should lead to a further increase in coherence time for @xmath0 spectral density of noise.@xcite for noise spectrum without sharp ultra - violet cutoff , which is the case considered here , the cpmg sequence marginally outperforms other sequences.@xcite furthermore , taking into account the simplicity of cpmg sequence ( defined by @xmath153 and all the other @xmath154 ) , we believe that it is a preferred approach of noise suppression for the problem at hand . @xcite we therefore propose that detailed experimental investigation of superconducting charge qubit dephasing behavior be carried out in order to test our specific predictions . we consider the spin - fermion model for quantum decoherence in solid - state qubits in the pure dephasing ( i.e. @xmath155 ) situation . we map the evolution of the qubit interacting with the fermionic environment , possibly subject to various @xmath25-pulse sequences , onto the keldysh path integral . this approach is very general and allows one to apply well - developed many - body techniques to the problem of the evolution of the qubit coupled to the environment and driven by pulses . in the short - time limit , we derive the expression for the qubit decoherence which involve the product of the noise spectral density due to quantum fluctuations of the bath and the filter function representing a particular pulse sequence . for a non - trivial interacting model of the bath , the andreev fluctuator model , we show that the spectral density has @xmath0 dependence at low frequencies . finally , we discuss the optimal strategy for the suppression of @xmath0 charge noise by the application of higher - order ( beyond spin echo ) pulse sequences for the problem at hand . one of our concrete conclusions of experimental significance is that the well - established cpmg pulse sequence should be an optimal method for fighting @xmath156 dephasing when the noise spectrum has no sharp ultra - violet cutoff . we thank a. kamenev , j. koch , y. nakamura , e. rossi , b. shklovskii , f. wellstood and n. zimmerman for stimulating discussions . this work was supported by the lps - nsa - cmtc grant and by the joint quantum institute ( rl ) .

we consider quantum decoherence in solid - state systems by studying the transverse dynamics of a single qubit interacting with a fermionic bath and driven by external pulses . our interest is in investigating the extent to which the lost coherence can be restored by the application of external pulses to the qubit . we show that the qubit evolution under various pulse sequences can be mapped onto keldysh path integrals . this approach allows a simple diagrammatic treatment of different bath excitation processes contributing to qubit decoherence . we apply this theory to the evolution of the qubit coupled to the andreev fluctuator bath in the context of widely studied superconducting qubits . we show that charge fluctuations within the andreev - fluctuator model lead to a @xmath0 noise spectrum with a characteristic temperature depedence . we discuss the strategy for suppression of decoherence by the application of higher - order ( beyond spin echo ) pulse sequences .

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consider some finite classical system which depends on an external parameter , @xmath0 . for instance , the system might be a lattice of coupled classical spins , and @xmath0 may denote the strength of an externally applied magnetic field ; or , the system might be a gas of particles , and @xmath0 a parameter specifying the volume of a box enclosing the gas . now suppose that , after allowing the system to come to equilibrium with a heat reservoir at temperature @xmath1 , we change , or `` switch '' , the external parameter , infinitely slowly , from an initial ( say , @xmath2 ) to a final ( @xmath3 ) value . the system will remain in quasi - static equilibrium with the reservoir throughout the switching process , and the total _ work _ performed on the system will equal the helmholtz free energy difference between the initial and final configurations@xcite : @xmath4 here @xmath5 denotes the equilibrium free energy of the system at temperature @xmath1 , for a fixed value of @xmath0 . the subscript on @xmath6 reminds us that this result is valid for infinitely slow switching of the parameter . now , what happens if , after allowing the system and reservoir to equilibrate , we switch the value of @xmath0 at a _ finite _ rate ? in this case the system will lag behind quasi - static equilibrium with the reservoir , and the total work will depend on the microscopic initial conditions of system and reservoir . thus , an _ ensemble _ of such switching measurements each prepared by first allowing the system to equilibrate with the reservoir will yield a distribution of values of @xmath6 . let @xmath7 denote this distribution , where @xmath8 is the `` switching time '' over which the value of @xmath0 is changed from 0 to 1 . ( without loss of generality , assume a uniform switching rate : @xmath9 . ) in other words , @xmath10 is the probability that the work performed in switching @xmath0 from 0 to 1 , over a time @xmath8 , will fall between @xmath6 and @xmath11 . in the limit @xmath12 , we get @xmath13 ( eq.[eq : infty ] ) , and so @xmath14 in this limit . for finite @xmath8 , however : ( 1 ) the distribution @xmath15 acquires a finite width , reflecting the fluctuations in @xmath6 from one switching measurement to the next ; and ( 2 ) its centroid shifts to the right : @xmath16 as a result of dissipation ( see fig.[fig : schem])@xcite . eq.[eq : infty ] gives the free energy difference @xmath17 in terms of the work performed during a single infinite - time ( quasi - static ) process . by contrast , eq.[eq : ineq ] gives an upper bound on @xmath17 , from an ensemble of finite - time ( hence , nonequilibrium ) repetitions of the switching process . recently@xcite , it was shown that one can in fact extract the value of @xmath17 itself , not just an upper bound , from the information contained in @xmath7 . specifically , the following result was shown to be valid _ for any switching time _ @xmath8 : @xmath18 where @xmath19 . this result gives the value of an equilibrium quantity , @xmath17 , in terms of an ensemble of finite - time , nonequilibrium measurements . as discussed in ref.@xcite and in section [ sec : comp ] below , the inequality @xmath20 , eq.[eq : ineq ] , follows immediately from eq.[eq : iden ] . eq.[eq : iden ] was derived by treating the system of interest and reservoir , coupled together , as a large , isolated , classical hamiltonian system . the hamiltonian governing the motion in the full phase space was taken to be a sum of three terms : one for the system of interest ( @xmath21 ) , one for the reservoir , and a final term , @xmath22 , coupling the two . the magnitude of the interaction term @xmath22 was explicitly assumed to be negligible in comparison with the other two terms . with these assumptions , eq.[eq : iden ] follows from the properties of hamiltonian evolution ( see ref.@xcite for details ) . the purpose of the present paper is to re - derive the same result within a different framework . instead of considering deterministic evolution in the full phase space containing both the system of interest and reservoir degrees of freedom we will treat only the evolution of the system of interest itself , described by a trajectory @xmath23 . this evolution will be stochastic rather than deterministic , and will be governed by a master equation . we will assume that this stochastic evolution is markovian , and that it satisfies detailed balance . in presenting this alternative derivation , we are motivated by several factors . first , master equations are a common tool in statistical physics , therefore it is reassuring to see that eq.[eq : iden ] follows in a natural way from the master equation approach . secondly , in this derivation there is no need to explicitly assume weak coupling between system and reservoir , since a reservoir _ per se _ does not enter into the analysis ; given the assumptions stated below , eq.[eq : iden ] is _ identically _ true . finally , one might come away from ref.@xcite with the feeling that that the validity of eq.[eq : iden ] depends directly on the properties of hamiltonian evolution , in particular liouville s theorem . the treatment herein dispels this notion : hamilton s equations appear nowhere in the derivation . this point is particularly relevant in the context of numerical simulations , where the evolution of a thermostatted system is often realized with the use of non - hamiltonian equations of motion . the plan of this paper is as follows . in section [ sec : prelim ] we establish notation and terminology , and specify precisely our assumptions regarding markovian evolution and detailed balance . in section [ sec : deriv ] we derive our central result . in section [ sec : examp ] we consider specific examples of stochastic processes for which the result is valid . in section [ sec : comp ] we briefly discuss the possible utility of eq.[eq : iden ] to the numerical computation of free energy differences . in section [ sec : numres ] we illustrate our central result with numerical simulations , and we conclude with a few remarks in section [ sec : sum ] . two appendices provide derivations of results used in the main text . we begin by specifying precisely what we mean by the terms _ work _ and _ free energy _ throughout this paper . we assume that there exists a phase space of variables ( e.g. the positions and momenta of constituent particles ) , such that the instantaneous microscopic state of our system is completely described by the values of these variables . let * z * denote a point in this phase space . the evolution of our system with time is then described by a trajectory @xmath23 . the kind of evolution which will most interest us is not the evolution of an isolated system , but rather that of a system in contact with a heat bath . hence the trajectory @xmath23 will in general be _ stochastic _ , reflecting the `` random '' influence of the heat bath . next , assume the existence of a parameter - dependent hamiltonian @xmath24 . the hamiltonian is just a function which , for a fixed value of @xmath0 , gives the total energy of the system of interest , in terms of its instantaneous state ( * z * ) . the value of @xmath0 thus parametrizes the external forces acting on the system ( arising from , e.g. , external fields , confining potentials , etc . ) when the system is isolated , @xmath21 happens to generate the time evolution of the system , through hamilton s equations , but we will not make use of this property in deriving our central result . given @xmath24 , we now define [ eq : fdef ] @xmath25 where @xmath26 is a real , positive constant . ( we are being a bit cavalier with units here : @xmath27 should be divided by a constant to make it dimensionless . however , since this constant only shifts the value of @xmath5 by a fixed amount , and therefore does not affect the free energy difference @xmath28 , we ignore it . ) @xmath29 and @xmath30 are of course the _ partition function _ and _ free energy _ of the system , respectively , and @xmath31 is the temperature , in units of energy ( @xmath32 ) . however , in following the derivation presented below , it may be most convenient to view these quantities abstractly , rather than in connection with their physical significance : @xmath26 is just some positive constant , and @xmath29 and @xmath30 are the functions of @xmath26 defined by eq.[eq : fdef ] . in what follows , we will never compare free energies or partition functions at different temperatures , hence the dependence of @xmath5 and @xmath27 on @xmath26 will be left implicit . the central quantity of interest in this paper will be the free energy difference @xmath33 , for a fixed value of @xmath26 . as mentioned , the time evolution of the system of interest is described entirely by a ( stochastic ) phase space trajectory @xmath23 . in general , this evolution will depend on the externally imposed time - dependence of @xmath0 , describing the changing external fields to which the system is subject . let us consider the evolution of the system from an initial time , @xmath34 , to a final time , @xmath35 , over which the value of @xmath0 is `` switched '' from 0 to 1 at a uniform rate : @xmath36 . given this time - dependence of @xmath0 , and given the trajectory @xmath23 describing the evolution of the system , the total _ work _ performed on the system is the time integral of @xmath37 along the trajectory : @xmath38 where @xmath39 . for the evolution of an isolated hamiltonian system , this reduces to @xmath40 , by hamilton s equations ; in this case the work performed on the system is just the change in its energy . for a system in contact with a heat bath , however , this no longer holds , since there is a constant exchange of energy with the bath . we will assume that the evolution of our system in phase space is a _ markov process_@xcite . this means that the stochastic evolution @xmath23 is entirely characterized by the transition probability function @xmath41 . this gives the probability distribution for finding the system in a state * z * at time @xmath42 , given that at an earlier time @xmath43 it was known to be at @xmath44 . taking the derivative of @xmath45 with respect to @xmath46 and evaluating at @xmath47 , we get a function @xmath48 which gives the instantaneous transition rate from @xmath44 to * z * , at time @xmath43 . the dependence of @xmath49 on time arises through whatever external parameters of the system and reservoir are available and time - dependent . in our case we assume only one such parameter , @xmath0 characterizing external forces therefore we write @xmath50 in other words , the instantaneous transition rate @xmath49 from @xmath44 to * z * depends on @xmath43 only through the value of @xmath51 . let us now shift our focus from the description of a single system , to that of an _ ensemble _ of systems , each evolving according to the stochastic markov process just described . this ensemble represents infinitely many independent realizations of the switching process . if @xmath52 denotes the time - dependent distribution of this ensemble in phase space , then this distribution obeys [ eq : mast ] @xmath53 where @xmath54 . we will abbreviate this as @xmath55 where @xmath56 is a linear operator acting on the space of phase space densities @xmath57 . eq.[eq : mast ] is our master equation ; when the time - dependence of @xmath0 is known , and an initial distribution @xmath58 is specified , eq.[eq : mast ] uniquely determines the subsequent evolution of the phase space density @xmath57 . in addition to the markov assumption ( eq.[eq : mast ] ) , we will impose another assumption on our stochastic process : detailed balance . if @xmath0 is held fixed , @xmath23 becomes a _ stationary _ markov process , describing the evolution of a system in contact with a heat reservoir , when the external forces acting on the system are time - independent . under such evolution , the canonical distribution in phase space ( corresponding to the fixed value of @xmath0 ) ought to be invariant . by eq.[eq : mast ] , this is equivalent to the statement that @xmath56 annihilates the canonical distribution : @xmath59 this places a condition on the linear operator @xmath56 . we assume that our stochastic process satisfies this condition , and will refer to this assumption as _ detailed balance_. ( usually , detailed balance is expressed as the following , somewhat stronger assumuption : @xmath60 eq.[eq : stat ] follows immediately from eq.[eq : otherdb ] : just set the products of the cross terms equal , then integrate over @xmath44 . the distinction between eqs.[eq : stat ] and [ eq : otherdb ] is of little importance in the present context , so for simplicity we refer to eq.[eq : stat ] as detailed balance . ) having been led to assume detailed balance by considering the behavior of the system when @xmath0 is fixed , it may seem natural to make another assumption . namely , if our stochastic process is meant to describe a system in contact with a reservoir , then for fixed @xmath0 we expect the system to thermalize : after an initial relaxation time , the system samples its phase space canonically ; equivalently , an arbitrary initial ensemble @xmath61 relaxes to a canonical distribution in phase space . we may express this assumption formally , as : @xmath62 for any normalized @xmath61 . the operator @xmath63 appearing on the left is just the evolution operator corresponding to the equation of motion @xmath64 , for fixed @xmath0 . eq.[eq : therm ] says that any initial distribution @xmath61 relaxes to a canonical distribution , and then stays there . we will refer to this as the assumption of _ thermalization_. note that while thermalization ( eq.[eq : therm ] ) implies detailed balance ( eq.[eq : stat ] ) , the converse is not true . since it will turn out that the proof of eq.[eq : iden ] requires only the weaker assumption of detailed balance , and not the stronger thermalization assumption , we will assume in what follows that eq.[eq : stat ] holds , _ but not necessarily eq.[eq : therm ] _ , unless explicitly stated . [ physically , we expect both thermalization and detailed balance to hold , as long as our master equation describes a system in contact with a genuine heat reservoir . however , one can easily imagine situations in which the evolution satisfies eq.[eq : stat ] but not eq.[eq : therm ] . a specific example , which we will analyze in section [ sec : examp ] , is that of an isolated hamiltonian system . note that if thermalization does not hold , then the validity of eq.[eq : infty ] , @xmath65 , is not guaranteed , since that result assumes that during an infinitely slow switching process the system remains in quasi - static equilibrium with a reservoir . eq.[eq : iden ] nevertheless remains valid , provided detailed balance is satisfied . ] at this point we are ready to proceed with a proof of eq.[eq : iden ] . concrete examples of stochastic processes satisfying the assumptions made in this section will be discussed in section [ sec : examp ] , and numerically simulated in section [ sec : numres ] . the overbar appearing on the left side of eq.[eq : iden ] denotes an average over an infinite ensemble of independent realizations ( repetitions ) of the switching process . each realization is described by a trajectory @xmath23 , @xmath66 , specifying the evolution of the complete set of phase space variables as the external parameter @xmath0 is switched from 0 to 1 . the entire ensemble is then described by a time - dependent phase space density : at any time @xmath43 , @xmath52 represents a snapshot of the distribution of trajectories in phase space . since we assume that the system equilibrates with the reservoir ( with @xmath0 held fixed at 0 ) before the start of each realization , we have a canonical distribution of initial conditions@xcite : @xmath67 during the switching process , however , the ensemble does not ( in general ) remain in instantaneous canonical equilibrium . in other words , although the distribution @xmath68 is a ( stationary ) solution of eq.[eq : mast ] for @xmath0 _ fixed _ , it is not , in general , a solution of eq.[eq : mast ] when @xmath0 depends on time . thus , for @xmath69 , a snapshot of the trajectories will reveal a distribution @xmath52 which lags behind the canonical distribution corresponding to @xmath51 . the amount of lag present by the time a given value of @xmath0 is reached , will depend on how rapidly or slowly we performed the switching on the way to that value . for every trajectory @xmath23 in our ensemble , we can compute the total work @xmath6 performed on the system ( eq.[eq : work ] ) . our task is now to evaluate the ensemble average of @xmath70 . to do this , let us first define , for a given trajectory @xmath23 , a function @xmath71 which is the `` work accumulated '' up to time @xmath43 : @xmath72 thus , @xmath73 . now consider all those trajectories in the ensemble which happen to pass through the phase space point * z * at time @xmath43 , and let @xmath74 denote the average value of @xmath75 , over this particular subset of trajectories . finally , define @xmath76 note that @xmath77 , since @xmath78 for every trajectory . given these definitions , the ensemble average of @xmath70 may be expressed as : @xmath79 we will now solve for @xmath80 . the function @xmath81 obeys @xmath82 with @xmath54 . to see this , imagine for a moment that each trajectory @xmath23 in the ensemble represents a `` particle '' moving about in phase space . furthermore , assume that the `` mass '' of each particle is time - dependent , and is given by @xmath83 . each particle thus begins with mass unity : @xmath84 . the function @xmath74 is then the average mass of those particles which are found at a point @xmath85 at time @xmath43 , and @xmath81 represents the time - dependent _ mass density _ in phase space ( after normalization of the number density to unity : @xmath86 ) . this mass density is time - dependent for two reasons . first , ( a ) the mass of each particle changes with time , at a rate proportional to its instantaneous mass : @xmath87 this contributes a term @xmath88 to @xmath89 . secondly , ( b ) the mass density evolves due to the flow of particles , described by our master equation , @xmath90 . this flow of particles contributes a term @xmath91 adding these contributions , a and b , gives eq.[eq : dgdt ] . an alternative derivation of this evolution equation , based on a path integral formulation , is given in appendix a. given the initial conditions @xmath92 , eq.[eq : dgdt ] is solved by @xmath93 where @xmath54 , and @xmath94 denotes the canonical distribution in phase space , for a given value of @xmath0 . this result is easily verified with the help of eq.[eq : stat ] . then , using eq.[eq : avex ] , we finally arrive at @xmath95 _ q.e.d . _ a different proof of eq.[eq : iden ] has been discovered by gavin e. crooks@xcite . it is worthwhile to draw attention to a curious feature of the evolution of our `` mass density '' , @xmath81 . recall that the evolution of @xmath52 depends nontrivially on the rate at which we switch @xmath0 : at finite switching rates , @xmath52 lags behind the instantaneous equilibrium distribution . by contrast , the time dependence of @xmath81 is very simple : the mass density is determined uniquely by the instantaneous value of @xmath0 ; see eq.[eq : goft ] . thus , no matter how slowly or rapidly we switch @xmath0 from 0 to 1 , @xmath81 will always evolve through exactly the same continuous sequence of `` canonical '' mass densities , specified by eq.[eq : goft ] ; @xmath96 _ never develops a lag _ , in the sense that @xmath57 does . eq.[eq : goft ] also implies the result @xmath97 @xmath54 , which is in effect a restatement of our central result , eq.[eq : iden ] . we have shown that eq.[eq : iden ] is true for markovian processes satisfying detailed balance . let us consider a few examples of such processes . as a first case , we take deterministic evolution under the hamiltonian @xmath21 , as @xmath0 is varied from 0 to 1 : @xmath98 where @xmath99 denotes the poisson bracket . ordinarily , one would not call this a stochastic process , but of course it may be viewed as a special case of such . this evolution is markovian , and @xmath56 is just the poisson bracket operator : @xmath100 it immediately follows that detailed balance ( eq.[eq : stat ] ) is satisfied . the central result of this paper then tells us that , if we ( 1 ) start with a canonical distribution of initial conditions , @xmath101 , and ( 2 ) allow trajectories to evolve deterministically from these initial conditions ( eq.[eq : ham ] ) as @xmath0 is varied from 0 to 1 , then this ensemble of trajectories will satisfy eq.[eq : iden ] , regardless of how slowly or quickly we perform the switching . this result was proven more directly in ref.@xcite . since evolution under eq.[eq : ham ] describes an isolated system ( no heat bath ) , the thermalization assumption ( eq.[eq : therm ] ) is not met , and the work performed in the limit of infinitely slow switching will in general not equal the free energy difference : @xmath102 . eq.[eq : iden ] nevertheless remains true , even in this limit . this last statement is easily illustrated with a one - dimensional harmonic oscillator . let the hamiltonian be @xmath103 for a given temperature , the partition function is given by @xmath104 , and the free energy difference is @xmath105 let us now imagine a trajectory @xmath23 evolving under this hamiltonian , as @xmath0 is changed infinitely slowly from 0 to 1 ; assume for specificity that @xmath106 . since @xmath107 is an adiabatic invariant for the harmonic oscillator@xcite , we have @xmath108 , where @xmath109 ( @xmath110 ) is the initial ( final ) energy of the oscillator . the work performed on an isolated system is equal to the change in its energy , so we get @xmath111 e_0 $ ] . a canonical distribution of initial energies @xmath109 then leads , after some algebra , to the following ensemble distribution of values of @xmath6 : @xmath112 where @xmath113 denotes the unit step function . it is straighforward to verify that this distribution satisfies eq.[eq : iden ] . as another example , consider a single particle bouncing around inside a three - dimensional cavity with hard walls , where the shape of the cavity is a function of @xmath0 . let @xmath114 denote the volume of the cavity . the free energy difference is then @xmath115 . assume that , when @xmath0 is held fixed , the motion of the particle is ergodic over the energy shell ( the 5-dimensional surface of constant energy in 6-dimensional phase space ) ; also assume that @xmath116 . now , imagine that we allow the particle to evolve as @xmath0 is switched infinitely slowly from 0 to 1 . for this system the quantity @xmath117 is an adiabatic invariant@xcite , therefore the total work performed on a particle with initial energy @xmath109 is : @xmath118e_0 $ ] . taking an ensemble of such particles , defined by a canonical distribution of initial conditions ( at @xmath2 ) , we get @xmath119 where @xmath120 . as with the example of the harmonic oscillator , it is straightforward to show that this distribution @xmath15 satisfies eq.[eq : iden ] . next , let us consider modifying hamilton s equations , by adding both a frictional and a stochastic force : [ eq : langevin ] @xmath121 we have assumed a one - degree - of - freedom system , and a hamiltonian @xmath122 . let us furthermore take the stochastic force , @xmath123 , to represent white noise , with an autocorrelation function given by @xmath124 finally , let us impose a fluctuation - dissipation relation between the frictional and stochastic forces : @xmath125 an ensemble of trajectories evolving under the stochastic process just defined satisfies the fokker - planck equation , @xmath126 since eq.[eq : fp ] is of the form @xmath64 , this process is markovian . furthermore , inspection reveals that @xmath56 satisfies eq.[eq : stat ] , i.e. detailed balance holds . thus , the conditions for the validity of eq.[eq : iden ] are met : given an ensemble of systems evolving under this stochastic process , as @xmath0 is changed from 0 to 1 over a time @xmath8 , and given an initial distribution @xmath127 , we are guaranteed that this ensemble will satisfy @xmath128 , for any switching time @xmath8 . eq.[eq : langevin ] is a _ set of equations . if @xmath0 is held fixed , an ensemble of trajectories evolving under these stochastic equations of motion will relax to a canonical distribution on phase space . in other words , the evolution specified by eqs.[eq : langevin ] to [ eq : fd ] satisfies not only detailed balance , but the stronger assumption of thermalization as well . if we start with a canonical distribution , at @xmath2 , and then switch the value of the external parameter infinitely slowly to @xmath3 , then the ensemble of trajectories will remain in quasi - static equilibrium over the course of the switching process : @xmath129 the creeping value of @xmath0 thus drags @xmath52 through a continuous sequence of canonical distributions . furthermore , in this limit , the `` work accumulated '' will be the same function of time for every trajectory in the ensemble : @xmath130 ; each trajectory represents a system evolving in quasi - static equilibrium with the reservoir . thus , the quantity @xmath74 defined earlier is given , in this quasi - static limit , by @xmath131 it then follows that the function @xmath132 ( eq.[eq : gdef ] ) satisfies @xmath133 ( eq.[eq : goft ] ) , from which we get @xmath134 . of course , when we switch @xmath0 from 0 to 1 over a _ finite _ time @xmath8 , neither eq.[eq : quasi - stat ] nor eq.[eq : q ] will in general hold ; nevertheless , eq.[eq : goft ] , and therefore our central result , will remain valid , since eq.[eq : dgdt ] governs the time evolution of @xmath96 regardless of how slowly or quickly we switch the external parameter . the langevin equations above provide a simple method for numerically simulating the evolution of a thermostatted system ( i.e. a system in contact with a heat bath ) , without explicitly simulating the many degrees of freedom of the bath . the term @xmath123 may be implemented by generating a small , random momentum `` kick '' at each time step in the numerical integration of the equations of motion . this method works both for static hamiltonians and as in the case considered in the present paper for hamiltonians made time - dependent through the variation of an external parameter . in the past decade or so , methods for using explicitly _ deterministic _ equations of motion to simulate thermostatted systems , have proven very useful@xcite . these generally go under the name of _ isothermal molecular dynamics _ ( imd ) . typically , the heat bath is represented by one or more `` extra '' degrees of freedom . then , in the extended phase space which includes both the system of interest and the extra degree(s ) of freedom , the evolution is governed by a set of deterministic ( but non - hamiltonian ) equations of motion . these are tailored so that , when the hamiltonian describing the system of interest is static , the variables representing the system of interest explore phase space canonically , at least to a good approximation . an example of an imd scheme is _ nos ' e - hoover dynamics_@xcite , represented by the following equations of motion : [ eq : nh ] @xmath135 we have again assumed a kinetic - plus - potential hamiltonian ; the index @xmath136 runs over all @xmath137 degrees of freedom of the system , @xmath138 is the total kinetic energy of the system , @xmath139 is the thermal average of @xmath140 , and the parameter @xmath141 acts as a relaxation time . let us imagine a trajectory evolving in the extended phase space , @xmath142-space , under these equations of motion , as @xmath0 is switched from 0 to 1 . the work @xmath6 performed on the system of interest is defined , as before , by eq.[eq : work ] . while this expression does not explicitly contain the bath variable @xmath143 , @xmath6 is nevertheless a function of the full set of initial conditions , @xmath144 , since the evolution of the system of interest ( * z * ) is coupled to that of the heat bath ( @xmath143 ) . in ref.@xcite , it was shown that , if one started with a distribution of initial conditions in the extended phase space given by @xmath145,\ ] ] and if one then propagated an ensemble of trajectories from these initial conditions , under the nos ' e - hoover ( nh ) equations of motion , as @xmath0 was switched from 0 to 1 over a time @xmath8 , and computed the work @xmath6 for each trajectory , then eq.[eq : iden ] would hold identically for this ensemble . this was shown by inspection . our purpose here is to use the central result of the present paper to establish simple criteria for determining whether or not eq.[eq : iden ] is valid for a particular implementation of imd . in general , the heat bath is represented by @xmath146 variables , @xmath147 to @xmath148 . let @xmath149 ) denote a point in the @xmath150-dimensional extended phase space , where @xmath137 is the number of degrees of freedom of the system of interest . then the thermostatting scheme in question is defined by a set of deterministic equations of motion in this space : @xmath151 of which eq.[eq : nh ] is an example . an ensemble of trajectories evolving under these equations of motion may be described by a distribution @xmath152 which satisfies the continuity equation , @xmath153 now suppose that we can find a function @xmath154 such that the distribution @xmath155\ ] ] is stationary under the evolution defined by eq.[eq : scheme ] , when @xmath0 is held fixed . that is , @xmath156 ( for the nh equations , @xmath157 satisfies this condition . ) we will allow @xmath158 to depend on @xmath26 , and any other _ constant _ parameters , but not on @xmath0 . the distribution @xmath159 may be viewed as the `` canonical '' distribution in the extended phase space , since it is invariant when @xmath0 is held fixed . now define a function @xmath160 which we may think of as an _ extended hamiltonian_. ( this is not meant to imply that @xmath161 generates eq.[eq : scheme ] as a `` real '' hamiltonian would ; in general those equations are non - hamiltonian . ) by eq.[eq : nhdb ] : @xmath162 now forget for a moment the division between system of interest and heat bath , and treat the entire extended phase space as a phase space for some system of interest , for which a parameter - dependent energy function , @xmath163 , is defined . the evolution given by eq.[eq : scheme ] then satisfies the two conditions listed in section [ sec : deriv ] : ( 1 ) it is markovian ( eq.[eq : nhpde ] ) , and ( 2 ) it satisfies detailed balance ( eq.[eq : nhdb2 ] ) . thus , our central result , @xmath134 , is identically true for an ensemble of trajectories evolving under eq.[eq : scheme ] from an initial distribution @xmath164 , _ provided we replace @xmath24 by @xmath163 in computing @xmath6 and @xmath17_. however , it is easily verified that we will get exactly the same values for both @xmath6 and @xmath17 using @xmath163 , as we would obtain with @xmath24 . in the case of @xmath6 , this is because only the first term of @xmath161 ( namely , @xmath21 ) depends on @xmath0 ; for @xmath17 , it follows from the fact that the partition function for the extended hamiltonian factorizes into an integral over the @xmath85 variables and an integral over the @xmath143 variables , and only the former depends on @xmath0 . ( see the definitions of work and free energy , eqs.[eq : fdef ] and [ eq : work ] . ) these considerations lead to the following simple conclusion . suppose we have a system described by a hamiltonian @xmath24 , and we wish to compute the free energy difference @xmath165 . suppose furthermore that we are given a scheme for imd ; that is , we have a set of `` heat bath '' variables @xmath166 , along with equations of motion in the extended phase space , as per eq.[eq : scheme ] . then , if a function @xmath158 of the heat bath variables can be found such that the distribution @xmath167 is stationary under the equations of motion ( with @xmath0 fixed ) , then we can compute @xmath17 as follows . let an ensemble of trajectories evolve from an initial distribution @xmath168 , as @xmath0 is switched from 0 to 1 over a finite switching time @xmath8 . compute the work @xmath6 for each trajectory , as per eq.[eq : work ] , and then compute the ensemble average of @xmath70 . this average will equal @xmath169 . as a final example again , motivated by computer simulations let us consider the evolution of a _ monte carlo _ ( mc ) trajectory , as @xmath0 is switched from 0 to 1 . in this case both the trajectory and the parameter @xmath0 evolved in discrete steps , rather than continuously : @xmath170 the initial point in phase space , @xmath171 , is sampled from a canonical distribution , with the value of @xmath0 fixed at @xmath172 . one then imagines that @xmath0 changes abruptly from @xmath172 to @xmath173 ; as a result , a quantity of work @xmath174 is performed on the system . then , the system jumps to the next point in phase space , @xmath175 , generated from @xmath171 by a mc algorithm appropriate to the hamiltonian @xmath176 ( see appendix b ) . one then continues to alternate between discrete changes in @xmath0 and discrete mc jumps in phase space , until the entire `` trajectory '' ( @xmath177 ) is obtained , and the value of @xmath0 is 1 . the total work performed during this discrete switching process is : @xmath178.\ ] ] note that `` time '' does not enter into this scheme . the quasi - static limit is obtained by letting the number of steps become arbitrarily large : @xmath179 . let us now imagine that we generate an infinite ensemble of mc trajectories , each of length @xmath146 . we do this by implementing the above procedure repeatedly , each time feeding in a different string of random numbers to generate the initial conditions @xmath171 , and the subsequent mc steps . given such an ensemble , we compute the work @xmath6 performed on each trajectory ( eq.[eq : dwork ] ) , and then the ensemble average of @xmath70 . as shown in appendix b , this average will equal @xmath169 . this should come as no surprise : a trajectory generated by the mc algorithm is a _ markov chain _ , with detailed balance built into the individual steps . this evolution thus satisfies , in discretized form , the two assumptions required for the validity of eq.[eq : iden ] . let us now consider the two limiting cases @xmath180 and @xmath179 . the latter is the mc equivalent of the quasi - static limit . in this case our ensemble proceeds through a discrete , infinitesimally spaced sequence of canonical equilibrium distributions , and the work performed on each trajectory is @xmath17 , as per eq.[eq : infty ] . the result @xmath134 then follows automatically . in the opposite limit , @xmath180 , the work @xmath6 performed on a particular `` trajectory '' is given by @xmath181 eq.[eq : iden ] then reduces to : @xmath182 where @xmath183 denotes a canonical average with respect to @xmath2 . this result is a well - known identity for the free energy difference @xmath17 ; see eq.[eq : tp ] below . while eq.[eq : iden ] is interesting in its own right , it may additionally prove useful in the numerical computation of free energy differences . the field of free energy computations is decades old , with diverse applications , and a very large body of literature exists on the subject@xcite . in this section , without attempting a survey of the field , we discuss a few points relevant to the possible application of eq.[eq : iden ] to free energy computations . these comments expand on ones made in ref.@xcite . most methods of computing free energy differences are variants of either the _ thermodynamic integration _ ( ti ) or _ thermodynamic perturbation _ ( tp ) methods . ( for an exception to this statement , see the work of holian , posch , and hoover@xcite , where two new expressions for @xmath17 , based on time - integrated heat transfer , are derived within the framework of isothermal molecular dynamics . ) tp is based on the identity@xcite @xmath184 where @xmath185 denotes a canonical average with respect to a fixed value of @xmath0 . using a method such as monte carlo , one samples @xmath146 points in phase space from the canonical distribution corresponding to @xmath2 , and then one takes the average of @xmath186 over these @xmath146 points . in principle , the method is exact for @xmath179 ; in practice , unless the canonical distributions corresponding to @xmath187 and @xmath188 overlap to a significant degree , the average of @xmath186 will be dominated by points in phase space which are visited extremely rarely during the canonical sampling , so numerical convergence with @xmath146 will be prohibitively slow . one way to get around this problem is to break up the @xmath0-interval @xmath189 $ ] into small sub - intervals , then use eq.[eq : tp ] to compute the free energy difference corresponding to each sub - interval . other , more sophisticated methods of extracting the best efficiency from eq.[eq : tp ] have been developed over the years@xcite . ti is based on the identity@xcite @xmath190 the integral on the right may be evaluated by sampling @xmath191 points in phase space from each of @xmath192 different canonical distributions ( corresponding to equally spaced values of @xmath0 from 0 to 1 ) , for a grand total of @xmath193 points sampled . the average of @xmath194 is then computed at each value of @xmath0 , and from these @xmath192 averages the integral is obtained . with the exception of a few very simple systems ( e.g. ideal gases , harmonic oscillators ) , the standard way to obtain a canonical distribution is to first allow the system to `` age '' that is , to relax to an equilibrium statistical state under some mc or imd scheme . in implementing the numerical evaluation of @xmath195 , it is often too time - consuming to age the system independently at each of the @xmath192 selected values of @xmath0 . instead , the final point sampled at one @xmath0 value may be used to generate the initial point sampled at the next value of @xmath0 . of course , this means that at each @xmath0 ( except @xmath2 ) we are actually sampling from a slightly out - of - equilibrium distribution , which leads to a systematic error ( in fact , an over - estimate ) in the evaluation of the integral . a limiting case of this procedure arises when we take @xmath196 , i.e. exactly one point is sampled at each value of @xmath0 . this is the _ slow growth _ method@xcite . as stressed by reinhardt and coworkers@xcite , if we view the chain of points @xmath197 thus generated as a _ trajectory _ evolving in phase space ( as @xmath0 is switched from 0 to 1 ) , then the integral appearing on the right side of eq.[eq : ti ] represents the work @xmath6 performed on the system over the course of the switching process . this picture is a compelling one , as it attaches a very physical interpretation to the numerical evaluation of eq.[eq : ti ] : instead of computing an integral , we are simulating the evolution of a thermostatted system , with the idea that , in the limit of infinitely slow switching , the work performed on the system will equal the free energy difference @xmath17 . for a finite switching rate , the above - mentioned systematic error inherent in the slow growth method is simply a manifestation of the inequality @xmath20 ; see eq.[eq : ineq ] and refs.@xcite . this interpretation of free energy computations is referred to as _ adiabatic switching _ ( or _ finite - time variation _ ) , and indeed may be viewed as a separate method , distinct from thermodynamic integration . in the context of adiabatic switching , eq.[eq : iden ] says that , if we run an ensemble of finite - time ( or finite-@xmath146 , for monte carlo ) simulations of the switching process , using for instance one of the methods described in section [ sec : examp ] , then the average of @xmath70 over this ensemble of simulations will equal @xmath169 . assuming perfect numerical accuracy and an infinite ensemble of simulations , this is an _ exact _ statement . another way of putting it is as follows : for a single finite - time switching simulation , the value of @xmath70 provides an _ unbiased _ estimate of @xmath169 . by contrast , the value of @xmath6 gives a biased estimate of @xmath17 ( i.e. @xmath20 ) . indeed , the former statement implies the latter , in the same way that eq.[eq : tp ] implies the gibbs - bogoliubov - feynman inequality@xcite : @xmath198 . let us consider this for a moment . given a real function of a real variable , @xmath199 , it is easy to show that , if @xmath200 for all @xmath201 , then @xmath202 for any set of points @xmath203 . if these points are the result of random sampling from some ensemble , then eq.[eq : math ] , in the limit @xmath179 , may be rewritten as @xmath204 where the overbar denotes an ensemble average . applying this result to @xmath205 , with @xmath206 , we get @xmath207 this is identically true for any distribution @xmath208 . we may now combine this result with eq.[eq : iden ] to get @xmath20 . now , what if we perform a finite number , @xmath209 , of identical switching simulations ? let @xmath210 denote the work performed on the system during the @xmath211th simulation , and let @xmath212 be the average over these values . we may view the @xmath210 s as numbers sampled randomly from a distribution @xmath208 satisfying eq.[eq : iden ] . then the expectation value of @xmath213 provides a rigorous upper bound on @xmath17 : @xmath214 the double angular brackets , denoting _ expectation value _ , specifically mean an average over all possible sets of @xmath209 simulations . now , eq.[eq : iden ] suggests that , rather than @xmath213 , we consider the following quantity as our best estimate of @xmath17 : @xmath215 for @xmath216 , @xmath217 and @xmath213 are identical , and the expectation value of either is @xmath218 . for @xmath219 , by contrast , @xmath217 converges to @xmath17 , whereas @xmath213 converges to @xmath218 . for intermediate values of @xmath209 , the following inequality chain holds : @xmath220 ( both inequalities are derived by combining eqs.[eq : iden ] and [ eq : math ] with the definitions of @xmath213 and @xmath217 . ) in other words , as an estimate of @xmath17 , the `` exponential average '' , @xmath217 , is statistically less biased than the ordinary average , @xmath213 , for @xmath221 . on the face of it , the last statement seems to imply that , if we perform more than one switching simulation , then we are better off using @xmath217 rather than @xmath213 as our best guess ( or upper bound ) for @xmath17 . in practice , however , eq.[eq : iden ] may be subject to the same disease as the tp identity , eq.[eq : tp ] . namely , if the values of @xmath6 obtained from repetitions of the switching simulation typically differ from one another by much more than @xmath31 , then the average of @xmath70 will be dominated by values of @xmath6 which are very rarely sampled@xcite . thus , the convergence of @xmath217 to @xmath17 , in the limit @xmath219 , may be much slower than the convergence of @xmath213 to @xmath218 , in the same limit . in other words , for a finite number of switching simulations , @xmath217 may be subject to considerably larger _ statistical _ fluctuations than @xmath213 , even though its _ systematic _ error ( expectation value minus @xmath17 ) is , by eq.[eq : chain ] , smaller . the preceding comments point to the following tentative conclusion . if one runs a set of @xmath209 switching simulations , with the goal of computing @xmath17 , and if the spread in the values of work @xmath6 obtained is not much larger than @xmath31 , then the exponential average @xmath217 defined by eq.[eq : wxdef ] should provide a better estimate of ( or tighter upper bound on ) @xmath17 than the ordinary average @xmath213 . this conclusion is supported by a calculation by john e. hunter iii , as described in ref.@xcite ; see also the numerical illustrations in the following section . of course , a more detailed study of the possible utility of eq.[eq : iden ] to free energy computations should be made . in particular , it is not ruled out that there exist methods around the limitation mentioned in the previous paragraphs@xcite . in this section we illustrate our central result with numerical experiments . the first four sets of simulations involve a harmonic oscillator whose natural frequency is switched from @xmath222 to @xmath223 . the evolution is implemented using , in turn , each of the four examples discussed in section [ sec : examp ] . then , we present results involving a more complicated system : a gas of interacting particles inside an externally pumped piston . all of these cases satisfy the condition discussed at the end of section [ sec : comp ] , namely , the spread in the values of @xmath6 is not much greater than @xmath31 . ( otherwise , the convergence of @xmath217 to @xmath17 , in the limit of many simulations , would be poor . ) for the harmonic oscillator simulations , we take the hamiltonian given by eq.[eq : hoham ] , with @xmath224 , and @xmath225 as throughout this paper . also , we take @xmath226 . thus , the free energy difference is @xmath227 . in the first set of simulations , the oscillator is isolated ( it evolves under hamilton s equations , with @xmath0 time - dependent ) , although the initial conditions are sampled from a canonical ensemble corresponding to @xmath228 : @xmath229.\ ] ] five different values of the switching time were chosen : @xmath230 1.0 , 3.0 , 10.0 , 30.0 , and 100.0 , and for each @xmath8 a total of @xmath231 simulations were carried out . fig.[fig : ham ] shows the average value of work obtained at each switching time , @xmath213 , as well as the `` exponential average '' , @xmath217 . ( see eqs.[eq : wadef ] and [ eq : wxdef ] . ) since hamiltonian evolution satisfies detailed balance , but not thermalization ( as defined in section [ sec : prelim ] ) , we do not expect the work performed in the limit @xmath12 to equal the free energy difference @xmath17 . rather , we expect @xmath232 e_0 $ ] for a single trajectory ( see section [ subsec : hamev ] ) , and therefore , for a canonical distribution of initial energies , @xmath233 \beta^{-1 } = 1.5.\ ] ] the values of @xmath213 shown in fig.[fig : ham ] are consistent with this expectation . eq.[eq : iden ] , meanwhile , predicts @xmath234 for _ any _ value of @xmath8 . again , the numerical results are consistent with the prediction : the values of @xmath217 shown in fig.[fig : ham ] all fall very close to @xmath17 . for the second set of simulations , we added a frictional and a stochastic force , as described by eqs.[eq : langevin ] to [ eq : fd ] , with @xmath235 and @xmath226 . the evolution now represents that of an oscillator coupled to a heat bath . the stochastic force was implemented by generating a random momentum kick ( sampled from a gaussian distribution ) at each time step , @xmath236 , in the numerical integration . as with the hamiltonian evolution , @xmath237 simulations were performed at each of the five switching times , and the results for @xmath213 and @xmath217 are plotted in fig.[fig : lang ] . here we _ do _ expect that the work @xmath6 will approach @xmath238 as @xmath12 , and the results for @xmath213 support this . at the same time , the exponential average @xmath217 falls very close to @xmath17 for each switching time , as predicted by eq.[eq : iden ] . the next simulations again involved a thermostatted harmonic oscillator , only this time isothermal molecular dynamics was used to implement the coupling to the heat bath . the particular imd scheme used was developed by hoover and holian@xcite , and involves two heat bath variables , @xmath143 and @xmath239 . the equations of motion in the extended phase space are [ eq : imdeq ] @xmath240 where @xmath141 is a relaxation time whose value was set to unity . a total of @xmath231 switching simulations were performed , with a swtiching time @xmath241 . at the start of each simulation , initial conditions were sampled from the distribution @xmath242.\ ] ] it is easily verified by inspection that , if the value of @xmath0 were held fixed at 0 , then this distribution would be invariant under eq.[eq : imdeq ] . this is therefore the `` canonical distribution '' corresponding to this imd scheme , and the function @xmath158 defined in section [ subsec : imd ] is given by : @xmath243 this set of simulations was used to illustrate eq.[eq : goft ] , evaluated at @xmath35 . ( see the discussion at the end of section [ sec : deriv ] . ) fig.[fig : imd1 ] is a scatter plot showing the distribution of final values in phase space , @xmath244 , for the @xmath237 trajectories . fig.[fig : imd2 ] shows several contour lines of this distribution , after smearing each point with a gaussian of variance 0.04 in both the @xmath201 and @xmath245 directions . thus , the lines shown are actually contours of the function @xmath246\ , \delta_\epsilon[p - p_i(t_s)]\qquad,\qquad \epsilon = 0.04,\ ] ] where @xmath247 is a normalized gaussian of variance @xmath248 , and @xmath249 gives the phase space evolution of the @xmath211th trajectory in the ensemble of simulations . as can be seen from both figures , this distribution does not correspond to the canonical distribution for @xmath188 . indeed , its skewness illustrates the `` lag '' which develops between the evolving phase space density and the instantaneous canonical distribution . next , the solid lines in fig.[fig : imd3 ] show contours of the function @xmath250 defined in section [ sec : deriv ] , obtained from the same set of simulations . again , gaussian smoothing was used , so the solid lines are contours of the function @xmath251\ , \delta_\epsilon[p - p_i(t_s)]\exp -\beta w_i \qquad,\qquad \epsilon = 0.04,\ ] ] where @xmath210 is the total work performed on the system during the @xmath211th simulation . the dashed lines in fig.[fig : imd3 ] show the corresponding contours of the _ predicted _ `` mass density '' @xmath250 ( eq.[eq : goft ] ) , with the same gaussian smoothing function folded in . the agreement between the two sets of contours is very good . this shows that , indeed , when one assigns a weight @xmath252 to each of the points in the scatter plot , fig.[fig : imd1 ] , then the resulting weighted distribution is canonical , in the sense of eq.[eq : goft ] . in the final set of simulations involving the harmonic oscillator , we used monte carlo evolution , with the metropolis algorithm . here , the duration of a simulation is characterized by the number of mc steps , @xmath146 , rather than by a switching time @xmath8 . ten different values of @xmath146 were considered , @xmath253 , and for each a total of @xmath237 simulations were performed . fig.[fig : mc ] shows @xmath213 and @xmath217 for each value of @xmath146 ; as before , the results agree nicely with eqs.[eq : infty ] to [ eq : iden ] . fig.[fig : mc_dists ] shows @xmath254 the distribution of values of @xmath6 obtained from the @xmath237 simulations for each of the ten values of @xmath146 . although the distributions @xmath255 are quite different , the integral @xmath256 ( i.e. @xmath257 ) is independent of @xmath146 , as shown by the values of @xmath217 in fig.[fig : mc ] . as a final example , we take a system more complicated than a harmonic oscillator , namely , a gas of @xmath258 interacting particles inside a piston which is taken through one cycle of pumping . specifically , the particles are confined within a two - dimensional box with hard walls , whose initial dimensions are @xmath259 ; over the course of the switching process , one of the wall first moves inward until the area enclosed by the box is three - quarters of its initial value , and then back out again . this pumping of the piston is cosinusoidal : the @xmath260 and @xmath261 dimensions of the box are given by @xmath262 where @xmath263 and the total switching time is @xmath264 . in their interactions with one another and with the walls , the particles act as hard disks of radius @xmath265 ; between collisions each particle moves freely . ( thus , over a switching time @xmath264 , a typical particle suffers several collisions with other particles . ) work is performed on the gas each time a particle bounces off the moving wall . molecular dynamics was used for the evolution , i.e. continuous trajectories for the particles were computed as functions of time . however , at each time step in the integration of the equations of motion , a single particle was randomly selected , and a random `` kick '' a discrete change in the momentum of the chosen particle was generated . the kick was then either accepted or rejected according to the metropolis algorithm@xcite , corresponding to a temperature @xmath266 . this simulates coupling to a heat reservoir : if all the walls of the box were fixed , the gas would relax to thermal equilibrium from any initial conditions . fig.[fig : piston ] shows results obtained from @xmath267 such simulations . for each simulation , the initial conditions of the gas were chosen from a canonical ensemble ( @xmath266 ) , and the work performed on the gas , as a function of time , was computed . the horizontal axis shows time . the solid line gives the work performed on the gas up to time @xmath43 i.e. the `` work accumulated '' , @xmath71 averaged over all @xmath209 simulations . let @xmath268 denote this average , where @xmath269 is the work accumulated during the @xmath211th simulation . the dashed line gives the `` exponential average '' @xmath270 of the work accumulated . both @xmath271 and @xmath272 were computed from the same set of @xmath273 trajectories . since the piston returns to its initial position at the end of the switching process , the final free energy difference is zero : @xmath274 . we see that the dashed line indeed returns to zero at @xmath35 , with very good accuracy . by contrast , the average work performed on the system ( upper line ) ends at @xmath275 . this represents dissipated energy : the gas `` heats up '' when pumped at a finite rate . at intermediate times , we expect @xmath276 ( in the limit of infinitely many switching simulations ) , by eq.[eq : tiden ] . if the gas were truly ideal , then the free energy difference would be given by : @xmath277 where @xmath278 denotes the area enclosed by the box . however , since the particles do interact with one another , as hard disks , this expression for @xmath279 is not exact . nevertheless , the size of each particle is small enough ( @xmath265 ) that eq.[eq : ideal ] ought to represent an excellent approximation . the dotted line in fig.[fig : piston ] shows this approximation to @xmath279 . this line is very close to the exponential average ( dashed line ) , in confirmation of our central result , in the form given by eq.[eq : tiden ] . note that the dotted line represents the work that _ would have been _ performed on the gas , in the limit of infinitely slow switching ( @xmath12 ) . thus , in the dahsed line , we have effectively extracted this _ quasi - static _ behavior , from an ensemble of _ finite - time _ switching simulations ! the central goal of this paper has been to establish the ( exact ! ) validity of the result @xmath128 , within the framework of the master equation approach . this result is unusual , in that it expresses _ in the form of an equality _ ( rather than an inequality , e.g. eq.[eq : ineq ] ) the relationship between the work @xmath6 performed on an out - of - equilibrium system ( more precisely , on an _ ensemble _ of systems driven out of equilibrium by varying an external parameter ) , and the free energy difference @xmath17 between two equilibrium states of the system . a few comments are now in order . in classical statistical mechanics , the equilibrium `` state '' of a system is described by a canonical distribution in phase space : @xmath280 . its free energy is then given by @xmath281 where @xmath282 and @xmath283 . thus the free energy @xmath284 ( like the entropy @xmath285 ) is a quantity associated with a _ statistical ensemble _ of microscopic states of the system . when the system depends on some external parameter , then so does the canonical ensemble , as in turn does the free energy . the quantity @xmath17 of central interest throughout this paper has been the free energy difference ( at constant temperature ) between two such equilibrium ensembles , @xmath286 and @xmath287 . in deriving eq.[eq : iden ] , we introduced a time - dependent phase space density @xmath52 , describing the evolution of our ensemble of trajectories . note that , although the initial phase space density coincides with the canonical distribution used to compute the free energy @xmath288 , @xmath289 the final density does _ not _ ( typically ) coincide with the distribution for which @xmath290 is defined : @xmath291 this is due to the lag which develops between the ensemble of trajectories and an instantaneous canonical distribution in phase space . thus , @xmath17 is not the free energy difference between the initial and final states of the system@xcite , but rather as stated in the previous paragraph between two different canonical ensembles , @xmath292 and @xmath293 , only the former of which reflects the actual distribution of microscopic states of the system at any time during the switching process . another way of putting this is as follows . suppose we are interested in the free energy difference between two equilibrium statistical states of a system , @xmath294 and @xmath295 ( corresponding to @xmath292 and @xmath293 , respectively ) . ordinarily , we would compute or measure @xmath17 by _ reversibly _ carrying the system from @xmath294 to @xmath295 , i.e. by switching @xmath0 infinitely slowly . eq.[eq : iden ] tells us that , even if we switch _ irreversibly _ , so that the system ends up in some nonequilibrium statistical state @xmath296 , we can still extract @xmath297 from an ensemble of such measurements . [ of course , if we are dealing with a system which satisfies the thermalization assumption , then , at the end of the switching process , we can always , at no cost in work , hold the value of @xmath0 fixed and allow our ensemble to relax , for an additional time @xmath298 , to thermal equilibrium : @xmath299 . in this case the @xmath17 which appears on the right side of eq.[eq : iden ] _ does _ equal the free energy difference between the initial and final statistical states of the system . ] eq.[eq : iden ] was derived , as an identity , under the assumptions of markovian evolution and detailed balance , as spelled out in section [ sec : prelim ] . this derivation is complementary to the one presented in ref.@xcite , in which the degrees of freedom of the heat reservoir were treated explicitly . neither of the assumptions of section [ sec : prelim ] was assumed in ref.@xcite , but the coupling between system and reservoir was taken to be weak , so the result there was an approximate one , with small corrections expected from the small but finite interaction hamiltonian . of course , in a real physical system , neither the markov assumption nor detailed balance will be met exactly , so the derivation presented herein is strictly speaking valid only for a particular class of _ models _ of physical reality . nevertheless , because the result is exact for these models , and because the markov and detailed balance assumptions are often very good approximations for physical systems , the result is a useful one . furthermore , as illustrated in section [ sec : examp ] , models of thermostatted systems which are commonly used in theoretical and numerical studies _ do _ satisfy these assumptions ; eq.[eq : iden ] is therefore exactly valid for these models . it would be very interesting , of course , to find a physical system on which a laboratory ( as opposed to numerical ! ) experiment testing the validity of eq.[eq : iden ] would be feasible . as mentioned in ref.@xcite , such a system would almost certainly have to be micro- , or at most meso- , scopic in size . finally , from both a theoretical and a computational point of view , it would be worthwhile to consider possible extensions or generalizations of eq.[eq : iden ] . in particular , are analogous results valid for ensembles other than the canonical ensemble ( fixed @xmath146 , @xmath300 , @xmath1 ) considered here , e.g.microcanonical , grand canonical , isothermal - isobaric , etc ? presumably , the role of the helmholtz free energy @xmath284 would then be played by other thermodynamic potentials , for instance the gibbs free energy in the case of the isothermal - isobaric ensemble . i would like to thank j.e . hunter iii , w.p . reinhardt , and j. tams for sharing with me the results of unpublished numerical simulations . these discussions have contributed significantly to my understanding of the practical problems likely to arise when applying the central result of this paper to the computation of @xmath17 in complicated systems . this work was supported by the polish - american maria skodowska - curie joint fund ii , under project paa / nsf-96 - 253 . in this appendix we present a derivation of eq.[eq : dgdt ] different from the one given in section [ sec : deriv ] . for a given stochastic trajectory @xmath23 , the work @xmath6 is given by a path integral along that trajectory ( eq.[eq : work ] ) . we are interested in evaluating the average of @xmath70 over an ensemble of trajectories , obtained by sampling initial conditions from a canonical ensemble and then evolving stochastically from each of these initial conditions . the quantity @xmath301 thus constitutes a `` sum over all paths '' , with each path @xmath23 in our ensemble weighted by the factor @xmath70 . we may write this as @xmath302\ , \exp -\beta w,\ ] ] where @xmath303 denotes a measure in the space of paths @xmath23 ; @xmath304 $ ] denotes the probability density ( with respect to this measure ) of choosing @xmath23 by sampling randomly from the ensemble of trajectories ; and @xmath305 $ ] ( as per eq.[eq : work ] ) . let us now divide the time interval @xmath306 $ ] into @xmath146 time steps of duration @xmath307 , and let us denote a particular trajectory @xmath23 by its phase space locations @xmath308 at times @xmath309 , @xmath310 . thus , @xmath311 the limit @xmath179 ( with @xmath8 fixed ) is implied . choosing a euclidean measure in path space , @xmath312 the probability density for a particular path is @xmath313 = p({\bf z}_0 ) p_{\lambda_1}^{\delta t}({\bf z}_0\vert{\bf z}_1 ) p_{\lambda_2}^{\delta t}({\bf z}_1\vert{\bf z}_2 ) \cdots p_{\lambda_n}^{\delta t}({\bf z}_{n-1}\vert{\bf z}_n).\ ] ] here , @xmath314 is the probability distribution for the initial condition @xmath171 ; @xmath315 is the transition probability from @xmath44 to @xmath85 ( in time @xmath316 ) as a function of @xmath0 ; and @xmath317 . it is the markov assumption which allows this factorization . the work @xmath6 may be expressed as @xmath318 = \sum_{n=1}^n\ , \delta h_n({\bf z}_{n-1}),\ ] ] where @xmath319 . [ in writing eqs.[eq : prob ] and [ eq : appwork ] we implicitly assume that @xmath51 evolves in @xmath146 discrete steps @xmath320 which occur at times @xmath321 . this `` staircase '' evolution becomes @xmath225 in the limit @xmath179 . ] combining eqs.[eq : pathsum ] to [ eq : appwork ] , we arrive at @xmath322\,p({\bf z}_0 ) e^{-\beta\delta h_1({\bf z}_0 ) } p_{\lambda_1}^{\delta t}({\bf z}_0\vert{\bf z}_1 ) \cdots e^{-\beta\delta h_n({\bf z}_{n-1 } ) } p_{\lambda_n}^{\delta t}({\bf z}_{n-1}\vert{\bf z}_n).\ ] ] let us now introduce @xmath323\,p({\bf z}_0 ) e^{-\beta\delta h_1({\bf z}_0 ) } p_{\lambda_1}^{\delta t}({\bf z}_0\vert{\bf z}_1 ) \cdots e^{-\beta\delta h_m({\bf z}_{m-1 } ) } p_{\lambda_m}^{\delta t}({\bf z}_{m-1}\vert{\bf z}),\ ] ] where @xmath324 . this is the discretized version of the function @xmath81 introduced in the main body of the text : @xmath325 in particular , note that @xmath326 . this set of functions @xmath327 satisfy the recursion relation @xmath328 now , to first order in @xmath316 , we have @xmath329 combining this with our recursion relation gives ( to leading order ) @xmath330 = -\beta\,g_m({\bf z})\ , \delta h_{m+1}({\bf z})/\delta t + \int d{\bf z}_m\,g_m({\bf z}_m ) \,r_{\lambda_{m+1}}({\bf z}_m,{\bf z}),\ ] ] which becomes eq.[eq : dgdt ] in the limit @xmath179 . here we prove the assertion ( made in section [ sec : examp ] ) that eq.[eq : iden ] is identically true when the switching process is carried out using the monte carlo method . some of the steps in the proof will be similar to those in appendix a , but the assumption @xmath179 will not be made here . as mentioned in section [ sec : examp ] , a trajectory @xmath197 is obtained by alternating discrete changes in the value of @xmath0 with random jumps in phase space generated by the mc algorithm . this algorithm parametrized by the value of @xmath0 takes as input a point @xmath85 , and outputs a point @xmath44 . let @xmath331 denote the probability of generating an output @xmath44 from an input @xmath85 , for a given value of @xmath0 . detailed balance is built into the algorithm : @xmath332 for any @xmath0 . ( this may be accomplished by , e.g. , the metropolis method@xcite . ) thus , a canonical distribution of inputs @xmath85 gives a canonical distribution of outputs @xmath44 . the probability of obtaining a particular trajectory @xmath197 over the course of the entire switching process is then @xmath333 combining this with eq.[eq : dwork ] for the work , we get @xmath334\,{1\over z_0 } e^{-\beta h_0({\bf z}_0 ) } e^{-\beta\delta h_1({\bf z}_0 ) } p_{\lambda_1}({\bf z}_0\vert{\bf z}_1 ) \cdots e^{-\beta\delta h_n({\bf z}_{n-1 } ) } p_{\lambda_n}({\bf z}_{n-1}\vert{\bf z}_n),\ ] ] where @xmath335 . now notice that @xmath336 can be combined with @xmath337 to give @xmath338 . the only other factor in the integrand which depends on @xmath171 is @xmath339 . performing the integral @xmath340 , we get @xmath341 using eq.[eq : mcdb ] . this takes care of the first of the @xmath342 integrals appearing in eq.[eq : long ] . we now repeat this process , first combining @xmath343 ( obtained from the @xmath344 integration ) with @xmath345 to get @xmath346 , then integrating over @xmath175 , and so forth . at the end of this process of `` rolling up '' the factors and integrating , we are left with @xmath347 q.e.d . note that eq.[eq : goft ] for @xmath81 , derived within the framework of continuous - time evolution , also has a monte carlo counterpart . namely , for @xmath324 , let us define @xmath348 where @xmath349 gives the probability of sampling a particular sequence of phase space points in the first @xmath192 monte carlo steps , and @xmath350 is the work accumulated during those steps . thus , in terms of our ensemble of mc trajectories , @xmath351 is the weighted phase space density after @xmath192 steps , where the weight assigned to each trajectory is @xmath352 . then , writing an explicit expression for @xmath349 in the form given by eq.[eq : tprob ] , and rolling up factors and integrating as above , it follows easily that @xmath353 we assume these initial conditions regardless of whether or not the thermalization assumption mentioned above is met . thus even if , for instance , the system is isolated during the switching process , we still assume that it was earlier allowed to thermalize with some heat reservoir . for reviews and reference books , see t.p.straatsma and j.a.mccammon , annu.rev.phys.chem . * 43 * , 407 ( 1992 ) ; m.karplus and g.a.petsko , nature * 347 * , 631 ( 1990 ) ; d.l.beveridge and f.m.dicapua , annu.rev.biophys.biophys.chem . * 18 * , 431 ( 1989 ) ; c.l.brooks iii , m.karplus , and b.m.pettitt , adv.chem.phys . * 71 * , 1 ( 1988 ) ; _ simulations of liquids and solids _ , d.frenkel , i.r.mcdonald , g.ciccotti , eds . , chapter 2 ( north - holland , amsterdam , 1986 ) ; d.frenkel and b.smit , _ understanding molecular simulation : from algorithms to applications _ , chapter 7 ( academic press , boston , 1996 ) . this is easy to see : typically sampled values of @xmath6 are those within a standard deviation or so of the maximum of @xmath208 , while the values of @xmath6 which are most important in determining @xmath301 are those near the maximum of @xmath354 . as a general rule , the two sets will overlap significantly only if the function @xmath70 does not change much over one standard deviation in @xmath6 .

it has recently been shown that the helmholtz free energy difference between two equilibrium configurations of a system may be obtained from an ensemble of _ finite - time _ ( nonequilibrium ) measurements of the work performed in switching an external parameter of the system . here this result is established , as an identity , within the master equation formalism . examples are discussed and numerical illustrations provided .

p o p ! A dermatologist finds fame among those for whom watching a pimple explode recalls the butterflies of a first kiss. Photographs by Bobby Doherty Two years ago, Dr. Sandra Lee, a dermatologist in Southern California, opened an Instagram account. She viewed it as an experiment; the surface of the internet was riddled with unseen pockets of desire, weird subterranean pressures, and she was inclined to prod it, gingerly, until she found out how deep they ran. Her first posts were fairly scattershot, many uploaded from unsurprising places like the golf course or poolside, but she also made the somewhat unusual professional decision to document her work on patients: slicing out cancers, lasering unwanted tattoos, mending earlobes torn by overzealous piercers. She became fascinated by why certain of her posts were shared more than others. Her face — with its immaculate skin, white-white teeth, little nose, and big eyes — naturally lent itself to selfies. However, many of her most popular posts were not about her, or her adorable kids, or her luxe vacations, but of the least glamorous aspects of her work: specifically, videos of her popping zits, cysts, and blackheads. Lee, like most dermatologists, had never spent much time removing blackheads and whiteheads. In her opinion, performing “extractions” — a mundane, tedious, and nonessential procedure that was rarely covered by insurance — was labor better left for aestheticians. But a surprising number of her followers wrote that they fervently (if guiltily) enjoyed watching these simple dermal exorcisms. (“I love it so much 😫😫😫😫😫,” moaned a typical commenter.) Sensing an untapped audience, Lee began posting more videos of things popping from the skin, and her audience gradually grew. At first, she was wary of posting anything with too much “ick factor” — giant blackheads, say, or explosive cysts — for fear that she would upset the gentle people of the internet. However, her online fans didn’t seem to mind the ick; in fact, many of them relished it. Some fans reported that their mouths inexplicably watered when they saw a particularly juicy pop; others claimed that they found the videos so soothing that they used them as a sleep aid. Lee began setting videos to punnily titled music, like Duke Ellington’s “Just Squeeze Me (But Please Don’t Tease Me),” Mtume’s “Juicy Fruit,” and French Montana’s “Pop That.” She soundtracked one video to “People Are Strange” by the Doors. In the caption, she wrote, “People are strange. Strange because they like to watch this stuff. But I’ve realized you strange people are not alone — there are many of you!” For videos longer than 15 seconds, Lee turned to YouTube, where she adopted the sobriquet “Dr. Pimple Popper.” Around the same time, she discovered that there was an entire sub-channel on Reddit dedicated to enthusiasts of popping, or, as they often call themselves, “popaholics.” Back then, the most famous producer of popping videos was a doctor in New Delhi named Vikram Yadav, who was known for removing impossibly huge blackheads from the noses of his aging, sun-scorched patients. The vast majority of popping videos, however, were still homemade. The popaholics, a fastidious bunch, complained that these videos were often unsanitary and poorly filmed. Lee realized that she was uniquely situated to provide these people with what they craved — she had a never-ending supply of pimples and the expertise to remove them cleanly. One of the first films she posted to YouTube was of an octogenarian man with a swollen, misshapen nose (the result of a condition called rhinophyma). As Lee was inspecting him, she noted that his nose practically bristled with blackheads. She made him a proposition. If he allowed her to squeeze the blackheads from his nose and film it, she would perform the procedure for free. He agreed. To protect his anonymity, she referred to him only as “Mr. Wilson,” after his resemblance to Walter Matthau’s character in the film Dennis the Menace. That video — the first installment of what would become a series — shows her careful hands pressing a tiny metal loop, called an extractor, into the surface of the man’s nose. With each stroke of the extractor, a long tendril of whitish-gray sebum would burst forth. Sometimes multiple strings would appear simultaneously, like Parmesan cheese run through a rasp. “So gross but I can’t look away,” remarked one commenter. “I thought I was the only one who liked watching this!” wrote another. The video has since been viewed nearly 7 million times. Lee’s office is located in the town of Upland, California, an hour east of Los Angeles, where the San Gabriel Mountains rise like divine warts from the arid expanses of chaparral and strip mall. At the latest count, her YouTube account has amassed 850,000 subscribers and more than 350 million views. She has been invited to pop blackheads and cysts on the syndicated daytime TV show The Doctors. And she has begun building a brand. Her office is strewn with merchandise emblazoned with the Dr. Pimple Popper logo, which she sells online: mugs, trucker hats, coffee cups, and, of course, extractors. The majority of her income still comes from conventional procedures — Botox, vein removal, skin-cancer surgery — but her YouTube channel could easily bring in hundreds of thousands of dollars this year. One recent morning, Lee met with Mr. Wilson for another round of extractions. He arrived dressed in a pale-green safari shirt and a Members Only jacket. A taciturn man, he responded to most questions with grunts. He said that he had initially been reluctant to come to a skin doctor — it was his wife’s idea — but after the first procedure, he admitted that his nose did feel “cleaner.” “You were actually the start of all this,” Lee remarked to him, as he lay supine on the operating chair. “I don’t know if that’s something you’re really proud of or not. But I am.” These days, some patients pay Lee for medical procedures and receive complimentary blackhead extractions if they let the extraction be filmed (and sign a release form). However, as a gesture of gratitude, Lee has never billed Mr. Wilson for any of her work treating his rhinophyma, ­popping-related or not. Lee moved smoothly around her patient, making conversation and preparing the utensils of her craft. One of her many advantages over at-home poppers and aestheticians is that she is able to use anesthetic and surgical tools, which allow her to open pores that might otherwise remain blocked. Patients (and online viewers) universally praise her calm and friendly bedside manner, which she says she learned from her father, also a dermatologist, who was known for playing the ukulele for his patients. (“We have similar personalities,” her father noted. “But she has the advantage of being prettier.”) Anywhere Lee thought she might have to use her scalpel, she would first inject a squirt of anesthetic, a mixture of lidocaine and epinephrine, which, in addition to numbing the area, constricted the flow of blood. In the world of popping videos, blood, the stuff of life, is regarded as a pollutant. Not only is it unsightly, but if a video is too bloody, someone on YouTube is likely to flag it as gore, and the video can be taken down. So Lee was meticulous about sopping up any blood with gauze, and when she spoke about blood on-camera, she tended to use the word ooze instead. “I really try to keep things nice and clean,” she remarked. Lee began on the right side of Mr. Wilson’s nose, working her way down from the bridge to the bulb. Any easy blackheads she popped out with the extractor; the more deeply embedded ones received a delicate prick from the scalpel. Lee pressed hard and wiggled the extractor to pry loose the stubborn ones, leaving behind a series of U-shaped welts. When asked to rate the pain on a scale of one to ten, he judged it a five. After a while, Lee remarked that she had been pushing so hard that her hand had begun to cramp. Lee’s assistant Kristie hovered over Mr. Wilson’s face with an iPhone, filming each step of the procedure. On the iPhone’s screen, the surface of his skin was transformed into an alien planet where sandworms periodically erupted forth from porous red earth. Visually, it was more impressive onscreen than in real life — larger, somehow. But the camera fails to capture the olfactory aspect of these extractions. Later, in private, Lee likened the odor of this one to “pungent cheese.” When she was finished with the right side of his nose, Lee moved around to the left. There were noticeably fewer blackheads than during his first extraction, and fewer spectacular eruptions. Lee seemed to be growing slightly disappointed with the overall yield, until she pressed down on a rather inconspicuous-looking lump on the bridge of his nose and a several-inches-long ribbon of sebum tapewormed out. “It keeps going …” Lee said wonderingly. “See, you never know.” Once it had fully emerged, Lee lifted it up with the extractor and dangled it a moment in front of the camera, like a trophy fish. “You had a big one there just now!” she said to her patient-star. “That one was worth all of it.” According to popping aficionados, the sense of suspense and surprise is part of what lends the videos their hypnotic power; during a big pop, many viewers find themselves leaning in, holding their breath. “It’s like gambling,” Lee explained. “You never know when you’re going to hit a big one.” In the late 1990s, a Belgian artist named Wim Delvoye released an experimental art film called Sybille II, in which he captured shots of whiteheads erupting in slow motion on 75-mm. film, framed in extreme close-up so that they resembled creatures in a Jacques Cousteau film. Delvoye intended it to function as a commentary about adolescence and purity, a puncturing of art’s lofty pretensions, but once it was uploaded (without his knowledge) on YouTube, commenters began dubbing it “probably the best zit video out there!!” and “pimple popping porn!!!!” Delvoye said recently that all of the film’s pimples had come from a single source: a young art student the other kids called “Old Pizza.” He met with the boy for multiple sessions, waiting a month after each “harvest” for his pimples to ripen again. Because the film stock was expensive, each session became a high-stakes game. “You didn’t know what was going to come out of the skin,” Delvoye said. “Sometimes you said, ‘Oh, well, let’s try this one, but it’s not going to be anything’ — and it came, and it came, and it came! We were constantly surprised.” Delvoye has since lost track of Old Pizza and wasn’t sure whether the boy had even seen the final cut of the film. Likewise, almost none of Lee’s star patients have watched the videos of their extractions. Some simply don’t care; others find them a bit gross. Many of her patients are over the age of 70. (Blackheads tend to intensify with age, especially in sunny places like Upland.) Mr. Wilson said he had never bothered to watch his video. Neither had a kindly 86-year-old man known only as “Pops” (4,945,366 views), beloved by popaholics for his gentle personality and overactive sebaceous glands. A third patient, a sassy 79-year-old lady named Gerry, known to Lee’s fans for an enormous blackhead that was removed from her temple (6,927,531 views), seemed not to even understand what YouTube was. Gerry recounted the story of her extraction like this: “She asked me if she could take a picture, and she said it went on this … thing, and I got all these … things! And I said, ‘What?!’ ” Gerry was cheerfully bemused by the whole experience; back in her day, she noted, people wanted to look at beautiful young people. “Why would they want to see an old lady with all these wrinkles?” she wondered. “I can’t believe that. Why?” Dr. Sandra Lee. Photo: Bobby Doherty Recently, Lee posted a series of questions on the sub-Reddit r/popping to answer precisely this question. One hundred and one people responded. The respondents were men and women (though considerably more of the latter than the former) ranging in age from their teens to their 80s, including one grandmother, named Nana Shirley, who enlisted her daughter-in-law to type out her responses. One was a preschool teacher; another worked as a lawyer; a third was a priest. Some had suffered from severe acne in the past, others had never had a pimple. Many were ashamed and hid their obsession, but others were open and unabashed. Quite a few described chasing their loved ones around the house, trying to pop their zits. (One woman confessed that she had once stopped mid-coitus to pop a pimple on her boyfriend’s shoulder.) What nearly all of them had in common was a sense that watching a good pop gave them a feeling of deep, vicarious satisfaction. They variously compared that sensation to opening a sticky jar; unwrapping a present; finishing a work of art; pulling up weeds; burping; farting; making it to the bathroom just in time; the TV show Hoarders; the butterflies you feel in your stomach when you experience your first kiss; Sudoku; “seeing a real jerk get what’s coming to him”; a scary movie (“only not scary”); explosions in a Michael Bay film; a roller coaster; a sunset; a shooting star; a natural childbirth (“Gross and messy, but the end result is beautiful in a way”). This sensation is not limited to popping videos. YouTube also contains surprisingly popular videos of people removing plugs of earwax, shampooing filthy car seats, using wood glue to strip the dust from vinyl records, and power-washing the grime off a metal toolbox. But the intimacy and universality of pimple popping make it an exceptionally cathartic ritual. “Life is hard, so hard,” wrote one popaholic, a 34-year-old woman from Iowa who worked nights and weekends to support her 2-year-old son. “The only thing that makes me feel okay, even for a short period of time, are the videos. I watch them every single night. It’s my only escape right now. So, if you can, please thank Dr. Sandra for me, because I would probably be in a psychiatric hospital if I didn’t have her videos.” Like pornography, popping videos come in two main genres: soft and hard. Many popaholics report that while they started out only being able to handle soft pops (black- and whiteheads), they now crave something more hard-core: primarily cysts, abscesses, and fatty tumors called lipomas. After her appointment with Mr. Wilson, Lee had a patient lined up who she hoped would produce a spectacular hard pop. He was an RV salesman named Bill, with a golf-ball-size lump growing atop his leathery forehead. It appeared to be a pilar cyst. A special delicacy among popaholics, pilar cysts are sacs filled with a white toothpaste-y substance made of soggy, dead skin cells. They are not dangerous, but they are unsightly and can occasionally lead to painful infections. Bill said that it had been growing for the past seven years; it had previously been even bigger, but he had “squeezed the fuck out of that thing” until it burst. Then, over time, it grew back. Lee worked quickly, but when the tip of her scalpel cut into the cyst, two unfortunate things happened more or less simultaneously. First, a thin stream of liquid — what appeared to be a mixture of anesthetic and cyst-juice — jetted out from the incision and hit Lee in the neck. (“It’s like acid, burning a hole in my neck right now,” she joked.) Second, she discovered that inside, the cyst was composed almost entirely of tough, fibrous tissue. For the better part of an hour, she used a pair of scissors and a curette to scrape it out. (When she later sent a tissue sample to a lab, the results revealed that the lump had not been a cyst at all; it was a type of skin cancer.) Lee looked discouraged. Over the months, she had developed a keen sense of what popaholics will find satisfying. “It’s not rocket science,” she said. “You figure it out because they tell you. They’ll say ‘That was gross, there’s just too much bleeding’ or ‘That was awesome right there, like Silly String!’ ” Next up on the hard-pop roster was a young woman with a relatively rare condition known as eruptive vellus hair cysts on her back. They, too, refused to pop out cleanly. “You’re interesting, but not greatly satisfying,” Lee told her. “Sorry about that. You don’t take it personally, do you?” The following day, Lee saw a patient with a benign fatty tumor that adhered stubbornly to the skin and she had to cut it out in pieces. A few hours later, a lipoma walked in, on the back of an exterminator named Ronnie, but the same thing happened; she deemed it a “dud.” The pressure to capture one good, hard pop on film was mounting. Finally, in walked Geoffrey, a young guy in black athleticwear, with a smaller pilar cyst hidden beneath his short-cropped dark hair. “Well, we haven’t got any really great pops like this yet, so we’re hoping that you’ll be one,” Lee told him. “Are you going to deliver or not?” Geoffrey smiled nervously. Lee readied her tools and instructed Kristie to move the overhead light so her hand didn’t cast a shadow on the cyst. She numbed the area, made a small incision, and then placed two rubber-gloved thumbs on either side of the opening. She pushed: nothing. She pushed harder: nothing. Then she braced herself against the wall and pushed with all her strength … Pop! A pale, slippery, oblong object ejected neatly from the skin, like a white edamame bean. Kristie deemed the pop “perfect.” Lee stitched shut the wound, then brought the cyst around, on a bed of gauze, to show to her patient. Then Kristie turned the iPhone around and let him watch the video of it popping out of his skin. “Huh, I didn’t feel anything,” Geoffrey reflected. “I could tell when it was coming out, though. I just felt, like, a release or something? It’s just like if you’ve ever popped a pimple. I was just like: Whoa, crazy.” *A version of this article appears in the March 7, 2016 issue of New York Magazine.

– Warning: This story is not for the squeamish. We mean it. New York Magazine has a fascinating—if occasionally far too descriptive—profile on Dr. Sandra Lee, better known among so-called "popaholics" on the Internet as Dr. Pimple Popper. Lee, an otherwise typical Southern California dermatologist, accidentally stumbled upon a culture of people who enjoy watching pimples, blackheads, and other fluid-filled things pop when she started an Instagram account two years ago. Now, thanks to her dedicated popaholics, she's topping 900,000 followers on Instagram and 850,000 subscribers on YouTube. Lee says her viewers get satisfaction out of the unpredictable payoff of a good pop. "It’s like gambling,” she says. “You never know when you’re going to hit a big one.” So what compels nearly 7 million people to watch Lee remove a whole mess of blackheads from an 80-year-old man's nose? "Some fans reported that their mouths inexplicably watered when they saw a particularly juicy pop; others claimed that they found the videos so soothing that they used them as a sleep aid," New York Magazine explains. Whatever the reasons, it's become a lucrative side gig for Lee. She's selling Dr. Pimple Popper merchandise and could potentially make hundreds of thousands off her YouTube page this year. Lee is even starting to cater to the "hardcore" popaholics, moving beyond pimples to "cysts, abscesses, and fatty tumors." Though there is one part of the extraction experience she'll never be able to replicate for them: the "pungent cheese" smell. Read the full story here, if your stomach can handle it.

Story highlights Plane carrying men is scheduled to land at Washington base Kenneth Bae family has "been waiting for and praying for this day for two years" Director of National Intelligence James Clapper traveled to Pyongyang North Korea claims it received apology from President Barack Obama After months in detention, two Americans who had been held prisoner in North Korea soon will be back in the United States following a rare visit by a top U.S. official to the reclusive nation and a letter from President Barack Obama. Kenneth Bae and Matthew Todd Miller, the last two Americans detained in North Korea, were due to arrive at Joint Base Lewis-McChord in Washington state about midnight ET (9 p.m. PT). The pair were released after Director of National Intelligence James Clapper went to Pyongyang as an envoy of President Barack Obama, a senior State Department official told CNN. Clapper delivered a letter from Obama, addressed to North Korean leader Kim Jong Un, describing Clapper as "his personal envoy" to bring the Americans home, a senior administration official told CNN on Saturday. The letter was "short and to the point," the official said. Clapper did not meet with Kim. JUST WATCHED N. Korea releases two U.S. detainees Replay More Videos ... MUST WATCH N. Korea releases two U.S. detainees 02:13 Clapper had no guarantee he would bring the Americans home, a senior State Department official told CNN. The North Korean government issued a statement about the release, saying it received an "earnest apology" from Obama for the men's actions. It also said the two were "sincerely repentant of their crimes and (were) behaving themselves while serving their terms." Photos: Photos: Americans freed by North Korea Photos: Photos: Americans freed by North Korea Americans freed by North Korea – Kenneth Bae, who had been held in North Korea since 2012, greets his mother Myunghee Bae after arriving, Saturday, Nov. 8, 2014, at Joint Base Lewis-McChord, Washington, after Bae and Matthew Todd Miller, who was held in North Korea since April, 2014, were freed during a top-secret mission by James Clapper, U.S. director of national intelligence. Hide Caption 1 of 9 Photos: Photos: Americans freed by North Korea Americans freed by North Korea – Matthew Miller, top, walks off the plane after arriving back in the United States. Hide Caption 2 of 9 Photos: Photos: Americans freed by North Korea Americans freed by North Korea – The plane carrying Kenneth Bae, Matthew Miller and James Clapper, U.S. director of national intelligence, lands at Joint Base Lewis-McChord, Washington. Hide Caption 3 of 9 Photos: Photos: Americans freed by North Korea Americans released by North Korea – American Kenneth Bae is seen just before his release in Pyongyang, North Korea, on Saturday, November 8. Bae's sister, Terri Chung, told CNN that her family shed happy tears and spread the good news among relatives and friends. Relatives describe Bae as a devout Christian who arranged tours of North Korea. Hide Caption 4 of 9 Photos: Photos: Americans freed by North Korea Americans released by North Korea – Matthew Todd Miller, shown here shortly before his release, had been detained since April. He was convicted in September of committing "acts hostile" to North Korea. Hide Caption 5 of 9 Photos: Photos: Americans freed by North Korea Americans released by North Korea – U.S. Director of National Intelligence James Clapper is greeted by North Korean officials after arriving in Pyongyang on Friday, November 7. Hide Caption 6 of 9 Photos: Photos: Americans freed by North Korea Americans released by North Korea – James Clapper meets with North Korean officials on November 8, prior to the release of two Americans. Clapper delivered a letter from President Barack Obama, addressed to North Korean leader Kim Jong Un. Hide Caption 7 of 9 Photos: Photos: Americans freed by North Korea Americans released by North Korea – Bae and Miller on November 8 board the plane that will take them back to the United States. They were flown to a military base in Washington state. Hide Caption 8 of 9 Photos: Photos: Americans freed by North Korea Americans released by North Korea – The plane prepares to depart North Korea on November 8. Hide Caption 9 of 9 JUST WATCHED 2009 detainee describes time in N. Korea Replay More Videos ... MUST WATCH 2009 detainee describes time in N. Korea 01:32 JUST WATCHED Former detainee's advice: Keep the faith Replay More Videos ... MUST WATCH Former detainee's advice: Keep the faith 02:38 According to the statement, the first chairman of North Korea's National Defense Commission ordered the release. The title is one of several top positions that Kim holds in the North Koran hierarchy. China assisted in the monthslong process of arranging the release, the official said. Clapper's visit came after North Korea contacted the U.S. government unexpectedly and urged the administration to send a Cabinet-level official to North Korea's capital to discuss the detained Americans, according to two sources close to the matter. A U.S. official told CNN that Washington believes Pyongyang reached out to show it had the clout to get a Cabinet-level official to come and doing so would help solidify Kim's power. The request came about two weeks ago, the official said. Clapper ended up canceling an event in New York on Wednesday as the trip was being arranged, an Obama administration official said. He went to Pyongyang "prepared to listen" on other issues, but that his sole focus was to bring Bae and Miller home, according to the same official. In fact, an official in Clapper's office said the talks didn't even touch on North Korea's controversial nuclear program. And other U.S. officials said there was no "quid pro quo" for the men's release. 'We are filled with joy' Clapper's office said the U.S. government is facilitating the two men's return home. Bae's family is to meet the plane but will not grant media interviews. Clapper and a U.S. delegation also are on the flight. Bae's sister, Terri Chung, told CNN that her family spent Saturday morning shedding happy tears and spreading the good news among relatives and friends. "Words cannot adequately express our relief and gratitude that Kenneth is finally coming home!" the family added later in a full statement. "We have been waiting for and praying for this day for two years. This ordeal has been excruciating for the family, but we are filled with joy right now." There was no immediate reaction from Miller's family. Photos: The photos N. Korea banned Photos: The photos N. Korea banned Photos North Korea didn't want you to see – A stern looking North Korean guard by the Chinese border customs office. This image was deleted by North Korean officials. Hide Caption 1 of 17 Photos: The photos N. Korea banned Deleting the offensive photos – Writer Johan Nylander and his guide, Ko Chang Ho, watch as a North Korean guard deletes 90 photos deemed unacceptable. Nylander was able to recover the photos with the help of an IT specialist -- the images that follow are an edited selection. Hide Caption 2 of 17 Photos: The photos N. Korea banned Hello, Dear Leader – This propaganda monument of "Dear Leader" Kim Jong-Il by a countryside road, not far from the border to China, was deleted by authorities. North Korea required images of leaders be full body shots. Hide Caption 3 of 17 Photos: The photos N. Korea banned Waiting for a train – People standing by the train track, while a guard is monitoring the bike race. Hide Caption 4 of 17 Photos: The photos N. Korea banned Watching the race – In the city of Rason, people are leaning out of windows to get a glimpse of the Western cyclists. Hide Caption 5 of 17 Photos: The photos N. Korea banned Pedestrian peasants – A woman and a man walking by the side of the road lined with cornfields. Hide Caption 6 of 17 Photos: The photos N. Korea banned Village life – Villagers waving by the race path. Hide Caption 7 of 17 Photos: The photos N. Korea banned Heavy security – Guards and custom officials by the border to China. Hide Caption 8 of 17 Photos: The photos N. Korea banned Secret volleyball court? – By the border checkpoint next to the Tumen River, North Korean customs officials can play volleyball. Officials prohibited any photos of North Korean military bases. Hide Caption 9 of 17 Photos: The photos N. Korea banned Photos North Korea didn't want you to see – Peasants and villagers standing by the road to look at the Western cyclists Hide Caption 10 of 17 Photos: The photos N. Korea banned Keeping watch – Guard keeping an eye on the bikers next to a small village. Hide Caption 11 of 17 Photos: The photos N. Korea banned Photos North Korea didn't want you to see – Kids playing outside village houses. Hide Caption 12 of 17 Photos: The photos N. Korea banned Waiting for the cyclists – Spectators waiting for the bikers to reach the finish line. In the background the "Great" and "Dear Leaders" Kim Il Sung and his son, Kim Jong-Il. Hide Caption 13 of 17 Photos: The photos N. Korea banned Standing on bikes to see cyclists – Huge crowds -- some of whom standing on their own bikes -- as they await cyclists by the race finish line in Rason. Hide Caption 14 of 17 Photos: The photos N. Korea banned Document check – Custom official and tourist bureau guide checking foreigners' passports. Hide Caption 15 of 17 Photos: The photos N. Korea banned Water checkpoint – Guides from the local tourist bureau handing out water bottles to bikers, monitored by a guard in the background. Hide Caption 16 of 17 Photos: The photos N. Korea banned Writer and his minder – Journalist Johan Nylander and his North Korean guide, Ko Chang Ho. EDITOR'S NOTE: This image was not among those deleted by North Korean officials. Hide Caption 17 of 17 JUST WATCHED U.S. detainees faced 'bizarre' charges Replay More Videos ... MUST WATCH U.S. detainees faced 'bizarre' charges 01:08 Obama expressed appreciation for Clapper's efforts "on what was obviously a challenging mission" and happiness Bae and Miller will soon be home. "It's a wonderful day for them and their families," the President said. Another American let go weeks earlier The Americans' departure from North Korea comes less than a month after North Korea released Jeffrey Fowle, an Ohio man who spent five months in detention. North Korean authorities took Fowle into custody after he left a Bible at a club in the northern part of the country. Bae had been held since late 2012, and in April 2013 was sentenced to 15 years of hard labor for "hostile acts" against the North Korean government. North Korea claimed that Bae was part of a Christian plot to overthrow the regime. The Lynwood, Washington, resident operated a China-based company specializing in tours of North Korea, according to family members, who have described him as a devout Christian. Earlier this year, Bae -- who was transferred to a hospital last year -- told a Swedish diplomat that he was worried about his health. Miller had been detained since April. According to the state-run Korean Central News Agency, he was convicted in September of committing "acts hostile" to North Korea and sentenced to six years of hard labor. He's been accused of tearing up his tourist visa and seeking asylum upon entry into North Korea. In September, all three Americans then detained in North Korea -- Bae, Fowle and Miller -- talked with CNN in Pyongyang for about five minutes apiece. All said they'd signed statements admitting their guilt, did not complain about their living conditions and asked for U.S. help. The interviews -- which CNN learned about only after being shuttled on a van to a secret location -- were monitored and recorded by North Korean officials. Talking Saturday, Fowle said that he'd been "upset" when he learned his fellow American detainees weren't going home with him last month. "Kenneth Bae and Matthew Miller should have been released before I was," Fowle told CNN. "But I'm glad to hear that they're on their way home now." In a statement, South Korea's Foreign Ministry welcomed the release of the two Americans and urged North Korea to release missionary Kim Jung-wook , who has been detained in the north on spying charges. It also asked North Korea to work with the south on humanitarian issues, such as family reunification. Ex-diplomat: North Korea may want to thaw U.S. relations CNN could not independently confirm details of the three Americans' detention or other facts about their cases, in part because of the secrecy that defines much of North Korea's dealings with the world. That includes the Communist nation's much-maligned quest to develop nuclear weapons, something that has put it at odds with the United States, South Korea and many other countries around the world. North Korea has been subject to stringent international sanctions aimed at curbing its nuclear aspirations. The State Department official said that Bae and Miller's release is "unrelated" to other U.S. issues involving North Korea. The United States welcomes the move, but if North Korea wants a better relationship with the world it needs to "show it is serious and prepared to abide by its commitments, particularly concerning denuclearization," the official said. "And they must take significant steps to improve their human rights record." Gordon Chang, the author of "Nuclear Showdown: North Korea Takes On the World," opines something must have changed in Pyongyang's philosophy to justify releasing three American detainees in less than a month. "I think right now there is a charm offensive," Chang told CNN. Bill Richardson, a former U.S. ambassador to the United Nations who tried to win Bae's release during a 2013 visit to North Korea, echoed that view, saying, "They are sending a message to the United States that 'we're ready to talk.'" He added that no decision this big would have been made without the approval of Kim, who took over as North Korea's absolute leader following the death of his father, Kim Jong Il, in 2011. "It appears that it is a good move by the North Koreans to restart the North Korean-American relationship, which has been in a really deep freeze," said Richardson. Former basketball star Dennis Rodman, who has been criticized for his chumminess with North Korea's leader, said in statement Saturday that his trips to the country influenced Bae's release. ||||| U.S. President Barack Obama answers a reporter's question about North Korea after naming U.S. Attorney for the Eastern District of New York Loretta Lynch as his pick to replace retiring Attorney General Eric Holder, in the Roosevelt Room at the White House in Washington... U.S. citizen Matthew Todd Miller (2nd R) sits in a witness box during his trial at the North Korean Supreme Court in Pyongyang September 14, 2014, in this photo released by Kyodo. Kenneth Bae, a Korean-American Christian missionary who has been detained in North Korea for more than a year, appears before a limited number of media outlets in Pyongyang in this undated photo released by North Korea's Korean Central News Agency (KCNA) on January 20, 2014.... U.S. citizen Matthew Todd Miller sits in a witness box during his trial at the North Korean Supreme Court in this undated photo released by North Korea's Korean Central News Agency (KCNA) in Pyongyang September 14, 2014. WASHINGTON North Korea freed two Americans from prison and they were returning to the United States on Saturday after the surprise involvement of the top-ranking U.S. intelligence official in their release. Kenneth Bae and Matthew Todd Miller, who had been doing hard labor for months in the reclusive country, were being accompanied home by Director of National Intelligence James Clapper, his office said. Their release comes less than three weeks after another American was freed by Pyongyang. Bae, a missionary from Washington state, was arrested in North Korea in November 2012 and sentenced to 15 years hard labor for crimes against the state. Miller, who reportedly was tried on an espionage charge, had been in custody since April this year and was serving a six-year hard labor sentence. The United States had frequently called for the men to be freed for humanitarian reasons, especially since Bae was said to have health problems. North Korea has been on a diplomatic campaign to counter charges by a U.N. body that highlighted widespread human rights abuses and a move by some U.N. members to refer the state to an international tribunal. But it was not clear what prompted Pyongyang to free the two men at this time. Their release did not constitute an opening in relations with North Korea, said a senior State Department official, who declined to be identified. The official said for that to happen, Pyongyang must fulfill its commitments on denuclearization and human rights. "He (Clapper) was not there to negotiate. And our position hasn't changed." The men were released just hours before President Barack Obama was to start a trip to Asia that will include talks with Chinese leaders about how Beijing can use its influence with North Korea to rein in its nuclear weapons program, U.S. officials have said. "It's a wonderful day for them and their families," Obama said at the White House. "Obviously we are very grateful for their safe return and I appreciate Director Clapper doing a great job on what was obviously a challenging mission." A senior U.S. official said: "The DNI (Clapper) did carry a brief message from the President indicating that Director Clapper was his personal envoy to bring the two Americans home." Myung Hee Bae, Kenneth Bae's mother, said she was told that her son would arrive soon at a U.S. Air Force base in Tacoma, Washington. She said she did not know when he was scheduled to arrive. Bae's delighted son, Jonathan, told Reuters from Arizona that he received a call Friday night and spoke to his father. "The brief time on the phone, he sounded good," Jonathan said. "I'm sure he will be back to his old self in no time." "It came out of the blue. One minute he was doing farm labor and the next minute they are saying, 'You are going home.' Just like everyone else, he was surprised," he said. CLAPPER'S ROLE As director of national intelligence, a job created after the Sept. 11, 2001, attacks on the United States, Clapper oversees the CIA and some 15 other intelligence agencies, making his involvement in the release surprising. U.S. officials said it was the first time a national intelligence director had been involved such a high-profile diplomatic matter. An Obama administration official, who declined to be identified, said there was no connection between Clapper's trip and the issue of North Korean nuclear weapons but that he acted as a presidential envoy with a broader mandate to listen to what North Korea had to say. Arrangements for the release had come together in the past several days and North Korea had asked for a high-ranking envoy to be involved, the official said. Clapper went to Pyongyang but there was no indication that he met personally with North Korean leader Kim Jong Un. The men's release came just a few weeks after North Korea freed another American, Jeffrey Fowle, 56 - a street repair worker from Miamisburg, Ohio, who had been arrested in May for leaving a Bible in a sailor's club in the North Korean city of Chongjin, where he was traveling as a tourist. U.S. Secretary of State John Kerry said in a statement: "We're pleased that this humanitarian gesture has taken place and that Kenneth Bae and Matthew Miller will soon be reunited with their families." U.N. Secretary-General Ban Ki-moon also welcomed the release, his office said in a statement, adding, "The Secretary-General hopes that this positive momentum for improving relations among the concerned parties for peace and security on the Korean Peninsula and beyond will be built on." INTERNATIONAL PRESSURE Victor Cha of the Center for Strategic and International Studies, said the release could indicate North Korea wants to press Obama on the eve of his Asian trip and that Pyongyang is feeling international heat from the U.N. resolution. "This is worrying to them," Cha said. "They have never seen anything like this before. Moreover, it is not coming from the U.S. but from the entire international community. They are trying to blunt criticism and perhaps water down the resolution with these actions." Miller, of Bakersfield, California, and said to be in his mid-20s, had gone to North Korea on a tourist visa, which state media said he tore up while demanding Pyongyang grant him asylum. The Associated Press reported Miller was tried on an espionage charge and prosecutors at his trial said he had falsely claimed to have secret information about the U.S. military stationed in South Korea. Bae's family said on its website that Bae had been operating out of China since 2006 and had led more than a dozen tours of North Korea. They said his health problems included diabetes, an enlarged heart, deteriorating vision and back and leg pains. (Writing by Bill Trott; Additional reporting by Brendan O'Brien in Milwaukee, David Brunnstrom in Washington and James Pearson in Seoul and Hyungwon Kang in Toronto; Editing by Frances Kerry, Stephen Powell, Sandra Maler and Bernard Orr)

– No more Americans are being held in North Korea: Pyongyang today released Kenneth Bae and Matthew Miller, both of whom had been sentenced to years of hard labor, reports CNN. As with the recent release of Jeffrey Fowle, it wasn't clear what prompted the move, though the State Department made a point to single out Sweden. "We want to thank our international partners, especially ... the government of Sweden, for their tireless efforts to help secure their release." Bae is a missionary who was convicted of crimes against the state in 2012 and sentenced to 15 years, while Miller is a 25-year-old Californian accused of espionage. He had recently begun serving a six-year sentence. Both men were reportedly on their way back to the US in the company of national intelligence director James Clapper, reports Reuters.

SECTION 1. SHORT TITLE. This Act may be cited as the ``Bulletproof Vest Partnership Grant Act of 1998''. SEC. 2. FINDINGS; PURPOSE. (a) Findings.--Congress finds that-- (1) too many law enforcement officers die, while protecting the public, as a result of gunshot wounds; (2) according to studies, between 1985 and 1994, 709 law enforcement officers in the United States were feloniously killed in the line of duty; (3) more than 92 percent of such law enforcement officers were killed by firearms; (4) the number of law enforcement officers who die as a result of gunshot wounds has declined significantly since the introduction of modern bulletproof material; (5) according to studies, between 1985 and 1994, bullet resistant materials helped save the lives of more than 2,000 law enforcement officers in the United States; (6) the number of law enforcement officers who are killed in the line of duty would significantly decrease if every law enforcement officer in the United States had access to an armor vest; and (7) the Executive Committee for Indian Country Law Enforcement Improvements reports that violent crime in Indian country has risen sharply, despite decreases in the national crime rate, and has concluded that there is a ``public safety crisis in Indian country''. (b) Purpose.--The purpose of this Act is to save lives of law enforcement officers by helping State and local law enforcement departments provide officers with armor vests. SEC. 3. PROGRAM AUTHORIZED. (a) Grant Authorization.--The Director of the Bureau of Justice Assistance is authorized to make grants to States, units of local government, and Indian tribes to purchase armor vests for use by law enforcement officers. (b) Uses of Funds.--Awards shall be distributed directly to the State, unit of local government, or Indian tribe and shall be used for the purchase of not more than 1 armor vest for each police officer in a jurisdiction. (c) Preferential Consideration.--In awarding grants under this Act, the Director of the Bureau of Justice Assistance may give preferential consideration, where feasible, to applications from jurisdictions that-- (1) have the greatest need for armor vests based on the percentage of officers in the department who do not have access to a vest; (2) have a mandatory wear policy that requires on-duty officers to wear armor vests whenever feasible; and (3) have a violent crime rate at or above the national average as determined by the Federal Bureau of Investigation. (d) Minimum Amount.--Unless all applications submitted by any State or unit of local government pursuant to subsection (a) have been funded, each qualifying State or unit of local government shall be allocated in each fiscal year pursuant to subsection (a) not less than 0.25 percent of the total amount appropriated in the fiscal year for grants pursuant to that subsection. (e) Maximum Amount.--A qualifying State or unit of local government may not receive more than 5 percent of the total amount appropriated in each fiscal year for grants pursuant to subsection (a). (f) Matching Funds.--The portion of the costs of a program provided by a grant under subsection (a) may not exceed 50 percent, unless the Director of the Bureau of Justice Assistance determines a case of fiscal hardship and waives, wholly or in part, the requirement under this subsection of a non-Federal contribution to the costs of a program. (g) Allocation of Funds.--At least half of the funds awarded under this program shall be allocated to units of local government or Indian tribes with fewer than 100,000 residents. SEC. 4. APPLICATIONS. (a) State and Tribal Applications.--To request a grant under this Act, the chief executive of a State shall submit an application to the Director of the Bureau of Justice Assistance, signed by the Attorney General of the State requesting the grant, or Indian tribe shall submit an application to the Director, in such form and containing such information as the Director may reasonably require. (b) Local Applications.--To request a grant under this Act, the chief executive of a unit of local government shall submit an application to the Director of the Bureau of Justice Assistance, signed by the chief law enforcement officer of the unit of local government requesting the grant, in such form and containing such information as the Director may reasonably require. (c) Renewal.--A State, unit of local government, or Indian tribe is eligible to receive a grant under this Act every 3 years. (d) Regulations.--Not later than 90 days after the date of enactment of this Act, the Director of the Bureau of Justice Assistance shall promulgate regulations to implement this section (including the information that must be included and the requirements that the States and units of local government must meet) in submitting the applications required under this Section. SEC. 5. PROHIBITION OF PRISON INMATE LABOR. Any State, unit of local government, or Indian tribe that receives financial assistance provided using funds appropriated or otherwise made available by this Act may not purchase equipment or products manufactured using prison inmate labor. SEC. 6. DEFINITIONS. For purposes of this Act-- (1) The term ``armor vest'' means-- (A) body armor which has been tested through the voluntary compliance testing program operated by the National Law Enforcement and Corrections Technology Center of the National Institute of Justice (NIJ), and found to comply with the requirements of NIJ Standard 0101.03, or any subsequent revision of such standard; or (B) body armor which exceeds the specifications stated in subparagraph (A), and which the law enforcement officer's agency or department permits the officer to wear on duty. (2) The term ``State'' means each of the 50 States, the District of Columbia, Puerto Rico, the United States Virgin Islands, American Samoa, and the Northern Mariana Islands. (3) The term ``qualifying State or unit of local government'' means any State or unit of local government which has submitted an application for a grant, or in which an eligible entity has submitted an application for a grant, which meets the requirements prescribed by the Director of the Bureau of Justice Assistance and the conditions set out in section 3. (4) The term ``Indian tribe'' has the same meaning as in section 4(e) of the Indian Self-Determination and Education Assistance Act (25 U.S.C. 450b(e)). SEC. 7. AUTHORIZATION FOR APPROPRIATIONS. There are authorized to be appropriated $25,000,000 for each fiscal year to carry out this program. SEC. 8. SENSE OF THE CONGRESS. In the case of any equipment or products that may be authorized to be purchased with financial assistance provided using funds appropriated or otherwise made available by this Act, it is the sense of the Congress that entities receiving the assistance should, in expending the assistance, purchase only American-made equipment and products.

Bulletproof Vest Partnership Grant Act of 1998 - Authorizes the Director of the Bureau of Justice Assistance to: (1) make grants to States, units of local government, and Indian tribes to purchase armor vests for use by law enforcement officers; and (2) give preferential consideration to applications from jurisdictions that have the greatest need, have a mandatory wear policy, and have a violent crime rate at or above the national average. Sets forth provisions regarding matching funds and allocation of funds, State, tribal, and local applications, and grant application renewal. Prohibits any State, unit of local government, or Indian tribe that receives financial assistance provided using funds appropriated or otherwise made available by this Act from purchasing equipment or products manufactured using prison inmate labor. Authorizes appropriations. Expresses the sense of the Congress that entities receiving assistance under this Act should, in expending such assistance, purchase only American-made equipment and products.

SECTION 1. SHORT TITLE. This Act may be cited as the ``Health Savings Account Expansion Act of 2016''. SEC. 2. ADEQUATE FUNDS FOR HEALTH INSURANCE PLANS. (a) In General.--Section 223(b)(1) of the Internal Revenue Code of 1986 is amended by striking ``the sum of the monthly'' and all that follows through ``eligible individual'' and inserting ``$9,000 ($18,000 in the case of a joint return)''. (b) Conforming Amendments.-- (1) Subsection (b) of such Code is amended by striking paragraphs (2), (3), and (5) and by redesignating paragraphs (4), (6), (7), and (8) as paragraphs (2), (3), (4), and (5), respectively. (2) Section 223(b)(2) of such Code (as redesignated by paragraph (1)) is amended by striking the last sentence. (3) Section 223(b)(4) of such Code (as redesignated by paragraph (1)) is amended to read as follows: ``(4) Medicare eligible individuals.--The limitation under this subsection for any taxable year with respect to an individual shall-- ``(A) in the case of the first taxable year in which such individual is entitled to benefits under title XVIII of the Social Security Act, be the amount which bears the same proportion to the amount in effect under paragraph (1) with respect to such individual as-- ``(i) the number of months in the taxable year during which such individual was not so entitled, bears to ``(ii) 12, and ``(B) be zero for any taxable year thereafter.''. (4) Section 223(g)(1) of such Code is amended-- (A) in the matter preceding subparagraph (A) by striking ``Each dollar amount in subsection (b)(2)'' and inserting ``In the case of taxable years beginning after December 31, 2017, each dollar amount in subsection (b)(1)'', (B) by amending subparagraph (B) to read as follows: ``(B) the cost-of-living adjustment determined under section 1(f)(3) for the calendar year in which such taxable year begins determined by substituting `calendar year 2016' for `calendar year 1992'.''. (c) Effective Date.--The amendments made by this section shall apply to taxable years beginning after December 31, 2016. SEC. 3. PARITY WITH EMPLOYER-PROVIDED HEALTH INSURANCE; DIRECT PRIMARY CARE. (a) In General.--Section 223(d)(2) of the Internal Revenue Code of 1986 is amended to read as follows: ``(2) Qualified medical expenses.-- ``(A) In general.--The term `qualified medical expenses' means, with respect to an account beneficiary, amounts paid by such beneficiary for medical care (as defined in section 213(d)) for such individual, the spouse of such individual, and any dependent (as defined in section 152, determined without regard to subsections (b)(1), (b)(2), and (d)(1)(B) thereof) of such individual, but only to the extent such amounts are not compensated for by insurance or otherwise. ``(B) Direct primary care.-- ``(i) In general.--Such term includes expenses for direct primary care service arrangements. ``(ii) Direct primary care service arrangements.--For purposes of clause (i), the term `direct primary care service arrangements' means an arrangement under which an individual is provided coverage restricted to primary care services in exchange for a fixed periodic fee or payment for primary care services.''. (b) Effective Date.--The amendments made by this section shall apply to taxable years beginning after December 31, 2016. SEC. 4. FREEDOM FROM MANDATE. (a) In General.--Section 223 of the Internal Revenue Code of 1986, as amended by sections 2 and 3, is amended by striking subsection (c) and redesignating subsections (d) through (h) as subsections (c) through (g), respectively. (b) Conforming Amendments.-- (1) Subsection (a) of section 223 of such Code is amended to read as follows: ``(a) Deduction Allowed.--In the case of an individual, there shall be allowed as a deduction for a taxable year an amount equal to the aggregate amount paid in cash during such taxable year by or on behalf of such individual to a health savings account of such individual.''. (2) Subsection (b) of section 223 of such Code (as amended by section 2) is amended by striking paragraph (5). (3) Section 223(c)(1)(A) of such Code (as redesignated by subsection (a)) is amended-- (A) by striking ``subsection (f)(5)'' and inserting ``subsection (e)(5)'', and (B) in clause (ii) by striking ``the sum of--'' and all that follows and inserting ``the dollar amount in effect under subsection (b)(1).''. (4) Section 223(f)(1) of such Code (as redesignated by subsection (a)) is amended by striking ``subsections (b)(1) and (c)(2)(A)'' and inserting ``subsection (b)(1)''. (5) Section 26(b)(U) of such Code is amended by striking ``section 223(f)(4)'' and inserting ``section 223(e)(4)''. (6) Sections 35(g)(3), 220(f)(5)(A), 848(e)(1)(v), 4973(a)(5), and 6051(a)(12) of such Code are each amended by striking ``section 223(d)'' each place it appears and inserting ``section 223(c)''. (7) Section 106(d)(1) of such Code is amended-- (A) by striking ``who is an eligible individual (as defined in section 223(c)(1))'', and (B) by striking ``section 223(d)'' and inserting ``section 223(c)''. (8) Section 408(d)(9) of such Code is amended-- (A) in subparagraph (A) by striking ``who is an eligible individual (as defined in section 223(c)) and'', and (B) in subparagraph (C) by striking ``computed on the basis of the type of coverage under the high deductible health plan covering the individual at the time of the qualified HSA funding distribution''. (9) Section 877A(g)(6) of such Code is amended by striking ``223(f)(4)'' and inserting ``223(e)(4)''. (10) Section 4973(g) of such Code is amended-- (A) by striking ``section 223(d)'' and inserting ``section 223(c)'', (B) in paragraph (2), by striking ``section 223(f)(2)'' and inserting ``section 223(e)(2)'', and (C) by striking ``section 223(f)(3)'' and inserting ``section 223(e)(3)''. (11) Section 4975 of such Code is amended-- (A) in subsection (c)(6)-- (i) by striking ``section 223(d)'' and inserting ``section 223(c)'', and (ii) by striking ``section 223(e)(2)'' and inserting ``section 223(d)(2)'', and (B) in subsection (e)(1)(E), by striking ``section 223(d)'' and inserting ``section 223(c)''. (12) Section 6693(a)(2)(C) of such Code is amended by striking ``section 223(h)'' and inserting ``section 223(g)''. (c) Effective Date.--The amendments made by this section shall apply to taxable years beginning after December 31, 2016. SEC. 5. RESTORING LOWER PENALTY FOR NONQUALIFIED DISTRIBUTIONS. (a) HSAs.--Section 223(e)(4)(A) of the Internal Revenue Code of 1986, as amended by section 4, is amended by striking ``20 percent'' and inserting ``10 percent''. (b) Effective Date.--The amendment made by this section shall apply to distributions made in taxable years beginning after December 31, 2016.

Health Savings Account Expansion Act of 2016 This bill amends the Internal Revenue Code to modify the requirements for health savings accounts (HSAs). The bill modifies the requirements to: increase the maximum contribution amounts, permit the use of HSAs to pay health insurance premiums and direct primary care expenses, repeal the restriction on using HSAs for over-the-counter medications, eliminate the requirement that a participant in an HSA be enrolled in a high deductible health care plan, and decrease the additional tax for HSA distributions not used for qualified medical expenses.

perhaps the most fundamental question to arise from these and other studies is whether tlr activation is critical for both the initiation and perpetuation of autoantibody production . mammalian dna or rna must enter discrete endocytic compartments within the cell in order to interact with intracellular tlrs ( such as tlr3 , 7 , 8 , and 9 ) . the only way that this has been achieved experimentally without the use of transfection is through engagement of igg nucleoprotein complexes with the antigen receptor on b cells or fc receptors on dcs ( 8) . furthermore , the most robust responses were observed when the target cells were first primed by exposure to ifn- or cd40 ligand ( cd40l ) ( 1 , 2 ) , a phenomenon explained in part by the ifn- or cd40l - induced up - regulation of tlr7 . from these in vitro studies , one can infer that during immune activation and after the production of antinucleoprotein autoantibodies in other words , when tolerance has already been broken the pathways described in these articles are likely to perpetuate immune activation and autoimmunity in vivo . viglianti et al . ( 9 ) showed that chromatin ingestion can occur through direct binding of chromatin to the bcr on b cells derived from transgenic mice expressing a dna - specific bcr , and that this chromatin ingestion triggers b cell proliferation . if b cell proliferation equates with maturation and autoantibody production ( as yet unproven assumptions , as discussed below ) , then the uptake of nucleoproteins directly through the bcr may initiate autoantibody production . however , as low - affinity antibodies specific for self - dna or rna are thought to be abundant in the peripheral circulation ( 10 ) , the avidity of interaction between the bcr and nucleoprotein , as well as the downstream signaling responses triggered by this interaction , and/or other environmental influences may be critical in determining whether pathogenic autoantibodies are produced . perhaps exposure to ifn- or other inflammatory cytokines , produced in response to inflammatory proteins released by dying cells ( 11 ) , are necessary coconspirators that are required to prime the immune system toward exaggerated responses . it is also possible that this process is sustained by defective clearance of apoptotic cells ( 12 ) ( fig . failure to establish self - tolerance during early b cell development allows the escape of autoreactive b cells , as recently shown in a small number of untreated sle patients ( 13 ) . if these b cells have sufficient avidity for self - nucleoproteins with repetitive epitopes that cross - link the bcr , the cells could become activated , endocytose the nucleoprotein , and be stimulated through their tlrs ( fig ( a ) a virus infection is sensed by tlrs in plasmacytoid dendritic cells ( pdcs ) resulting in the production of large concentrations of type i interferon ( ifn-/ ) . ifns prime the adaptive immune system to respond to other signals that may include nucleoprotein antigens released from dead and dying cells . virus persistence and/or defective clearance of apoptotic cells might drive chronic , self - perpetuating autoimmunity through uptake of nucleoprotein antigen antibody complexes ( fig . ( b ) defective b cell tolerance leads to capture of nucleoprotein antigens by autoreactive b cells , thereby triggering b cell activation , tlr stimulation , and antigen presentation to t cells . apoptotic cells are abundant in germinal centers , and nucleoprotein antigens may be released at other sites due to abnormal cell death or defective cell clearance . ( 1 ) the u1 snrnp binds to the bcr on a b cell or fcr on a dc . ( 2 ) ( 3 ) the receptor is endocytosed , and the endosome matures into a late endosome / lysosome containing tlr7 and 8 . ( 4 ) the u - rich rna , initially protected by the smrnp proteins and/or the antibody , now engages the tlr triggering activation of irf and nf-b signal transduction pathways . ( 5 ) the protein component dissociates and is degraded by lysosomal enzymes with membrane fusion to vesicles containing mhc class ii . ( 6 ) activated transcription factors induce expression of proinflammatory cytokines such as type i ifns , il-12 , il-6 , and tnf which ( 7 ) up - regulate mhc class ii and costimulatory molecule expression . cell activation may also lead to cell proliferation . throughout the decades after the discovery of autoantibodies in patients with lupus and related diseases , interest in these antibodies has waxed and waned . although often dismissed as epiphenomena , the remarkable disease specificity of these autoantibodies , as well as the association between certain autoantibodies and disease manifestations ( 10 ) , suggest that an understanding of how these antibodies are generated might provide insight into the mechanisms of disease . as autoantibodies in sle patients recognize components of chromatin ( such as dsdna , histones , and nucleosomes ) and u - rich ribonucleoproteins ( such as rnp and sm)all particles that are now known to activate tlrs ( 10)it can be proposed that selection of these particles for immune attack is based on their intrinsic ability to activate the tlrs the toll hypothesis . this hypothesis would explain why most autoantigens in sle and related diseases are nucleoproteins the nucleic acid component could serve as the adjuvant that stimulates cytokine production and the up - regulation of costimulatory molecules , thus facilitating the presentation of the associated peptides to t cells ( fig . sm / rnp is a particularly appropriate model antigen , as the highly conserved domains of sm that make up the hexameric or heptameric rings of the protein ( fig . 2 ) bind to the oligo - u consensus sequence rau5gr ( where r is any purine ) on u snrnas ( for review see reference 14 ) . if the toll hypothesis is correct , other common rnp antigens that are targeted in sle , such as ro ( ssa ) and la ( ssb ) , should also be tlr agonists . la associates with the 3 termini of a variety of newly synthesized small rnas ( including the rna polymerase iii transcripts , ro y rnas , u6 , pre - trnas , pre-5s , and 7sl rna , as well as small viral rnas ) and , at least in yeast , with polymerase ii transcripts ( 15 ) . a unifying explanation for the binding of rnps to these nascent transcripts is recognition of a short 3 oligo u tract , uuu - oh . it remains to be experimentally tested whether ro , la , and other ribonucleoprotein antigens that are targeted in sle are preferential activators of tlr7/8 . but the large number of possible u - rich regions in rnas of the snrnp family ( which includes at least 12 members ) , of small nucleolar rnas ( which number in the hundreds ) , and of mrnas that contain 3 u - rich regions , suggest that the property of being u , ug , or g rich is itself unlikely to be a sufficient explanation for autoantibody selection through tlr activation . could there be stimulatory sequences within these rnas similar to those described for dna and , more recently , for small interfering rnas ( 16 ) ? could one or more of the more than 100 known biochemical modifications of rna , such as methylation or pseudouridylation , explain differences in activation potential ? recently , it was shown that several of the modifications that occur primarily in mammalian , but not in bacterial , rnas protected transfected cells from intracellular tlr stimulation ( 17 ) . finally , the high abundance of u1 rna ( 10 copies per nucleus ) and the tight binding between the nucleic acid and the core proteins may confer a relative insensitivity to nucleases and the persistence of the particles both outside and inside the cell . if immunostimulatory dna and rna sequences or structures help to account for autoantibody specificity in sle , and very likely in sjogren 's syndrome ( 18 ) , a prediction is that the dominant nucleoprotein autoantigens in other systemic diseases , such as systemic sclerosis and polymyositis , will also stimulate tlrs . if self nucleic acids are capable of activating tlrs , how does the immune system avoid autoimmune activation of the sort described by lau et al . ( 1 ) and vollmer et al . the answer likely lies in the intracellular and intraendosomal location of tlr3 , 7 , 8 , and 9 , and the presence of highly abundant extra- and intracellular nucleases . serum contains high levels of dnase and rnase activity , which presumably help dissolve nucleic acids that leak out of dead and dying cells , particularly at sites of inflammation . a plethora of nucleases also exist within the cell some that assist in the processing of nucleic acid intermediates and others that appear to degrade foreign or ectopic nucleic acids . type ii dnases function optimally in an acidic environment ( such as in endosomes / lysosomes ) , the dnase1-like ( l ) family have been variously proposed to act in the nucleus , cytosol , and extracellular space , and several other dnases ( such as caspase - activated dnase and endonuclease g ) are required for cell - autonomous dna degradation ( 1921 ) . the inability to degrade dna in dnase ii mice results in high levels of ifn- production , although interestingly the inefficient removal of engulfed endogenous dna stimulates innate immunity through a tlr9-independent pathway ( 22 ) . extracellular or secretory rnases of the rnase a superfamily have a wide range of activities as demonstrated by differential catalytic activities on substrates such as single or double stranded rna and poly - c or poly - u ( for review see reference 23 ) . smrnp itself , as part of the spliceosome , excises intronic rna from pre - mrna by transesterification reactions . many rnases function in processing events at the 5 or 3 region of the rna , whereas others are selectively catalytic for rna / dna hybrids ( such as the rnase h family ) or double stranded rna ( such as the rnase iii superfamily ) , which include the recently recognized dicer the enzyme required for the generation of small interfering rnas . two enzymes , rnase l and isg20 , help to degrade viral rnas and are of particular interest , as they are induced by type i ifns . as mentioned previously , u - rich rnas in smrnp may be relatively resistant to nuclease attack . endosomal location can not be the only explanation for this resistance , as snrnps are assembled in the cytoplasm before their reimport into the nucleus . whether resistance is conferred by high - affinity binding of rnas to proteins or by specific patterns of protein shielding , nucleoprotein stability may be an important requirement for tlr stimulation . ( 1 ) reported that immune complexes containing rna stimulated b cell proliferation , but they did not show that stimulation led to b cell maturation and autoantibody production . although lymphocyte proliferation is often followed by maturation , for example , cd8 t cell proliferation in response to self - antigen is followed by death studies on the fate of b cells activated by nucleoprotein complexes are eagerly awaited . in the study by vollmer et al . ( 2 ) , the major consequence of tlr7/8 activation by u - rich rnas was the production of ifn- , a cytokine long known to be elevated in patients with sle . although the low ifn response in tlr7 mice suggests a dominant role for this receptor in response to u1 rna , it is relevant to note that both viral and mammalian nucleic acids may stimulate ifns through tlr - independent routes , as recently shown ( 2527 ) . of particular interest , rna helicases containing caspase - recruiting domains ( cards ) , such as rig-1 and mda5 , stimulate ifn production in response to intracellular , double stranded viral rna in a tlr - independent manner ( 28 , 29 ) . regardless of whether tlr engagement is required for the initiation and/or progression of autoantibody production , modulation of certain tlr pathways impacts autoantibody production , at least in murine models of sle . although studies performed to date have used mice with a mixed genetic background , they have consistently shown that both myd88 and tlr9 deficiencies reduced the level of serum autoantibodies ( 1 , 30 ) , suggesting that these pathways are required for high titer autoantibody production . although tlr9 deficiency reduced some anti - dna antibodies , it did not protect mice from glomerulonephritis ( 30 ) . this could occur either because the lack of tlr9 altered the isotypes or affinity of the anti - dna antibodies ( not tested in this study ) , or because nephritis was caused by a different subset of autoantibodies . since oligonucleotide - based inhibitors of both tlr9 and 7 have been developed ( 31 ) , their therapeutic application for treatment of sle is an exciting prospect ( 32 ) . there is currently no unifying hypothesis to explain autoantigen selection in systemic autoimmune disorders . here , we propose that a necessary property for the selection of nucleoprotein autoantigens is their ability to activate intracellular tlrs . according to the toll hypothesis , the nucleic acid component of rnps serves as an adjuvant , and the protein component is processed by the activated apc and presented to t cells ( fig . other critical abnormalities that sensitize immune cells and provide a constant source of antigen , or that facilitate uptake of nucleoproteins ( fig . nevertheless , at least part of the answer to the 50-yr - old puzzle of autoantibody specificity now seems to be solved .

like the immune response itself , our efforts to understand the rules for self nonself discrimination are constantly evolving . the discovery of pattern recognition receptors the toll - like receptor ( tlr ) family in particular shifted the emphasis of self nonself recognition from lymphocytes functioning in the adaptive immune system to antigen - presenting cells ( apcs ) functioning in the innate immune system . two new articles , one in a recent issue ( 1 ) and one in this issue ( see vollmer et al . [ 2 ] on p. 1575 ) , demonstrate that antigen antibody complexes containing rnas activate b lymphocytes and dendritic cells ( dcs ) through interaction with tlr7 and/or tlr8 . from these and other papers , one begins to see how specific types of autoantigens by virtue of their capacity to act as tlr ligands favor autoantibody production . this is known as the toll hypothesis .

SECTION 1. SHORT TITLE. This Act may be cited as the ``Afghan Women Empowerment Act of 2006''. SEC. 2. FINDINGS. Congress makes the following findings: (1) Under the oppressive rule of the Taliban, the women of Afghanistan were denied the most basic human rights, including the rights to work, to an education, to health care, and to move freely. (2) Women who attempted to assert their rights under the Taliban regime were subjected to beatings and imprisonments, and many suffer from the long-term consequences of such oppression. (3) Women in Afghanistan have one of the highest mortality rates in the world, with an estimated 16,000 maternal deaths annually. (4) Despite efforts by the United States Government and the international community to improve the lives of women and girls in Afghanistan, many women and girls continue to lack access to basic services, including health care and education. Approximately 80 percent of Afghan women are illiterate. (5) Today, women and girls in Afghanistan still face oppression resulting from violence and intimidation by Taliban and other militia groups. In recent months, there has been a significant increase in the number of attacks against girls' schools in an attempt to prevent women and girls from regaining their rights and freedoms. (6) The strengthening of institutions and nongovernmental organizations that are led by women in Afghanistan is essential to building civil society and holding the Government of Afghanistan accountable for protecting women's rights and human rights. SEC. 3. SENSE OF CONGRESS ON WOMEN'S RIGHTS IN AFGHANISTAN. It is the sense of Congress that-- (1) the protection of the rights of women and girls in Afghanistan and their full participation in the reestablishment of democracy are essential to the reconstruction of a stable and democratic Afghanistan, and to achieve such a reconstruction, the United States Government must commit resources to advance the rights of women throughout Afghanistan; (2) the United States Government should provide strong support for the Afghan Ministry of Women's Affairs and the Afghan Independent Human Rights Commission, both of which were created by the Agreement on Provisional Agreements in Afghanistan Pending the Establishment of Permanent Governing Institutions, done in Bonn December 5, 2001 (commonly known as the ``Bonn Agreement'') to remedy past violations of women's rights and human rights and to establish institutions and programs to ensure policies that advance such rights; (3) the United States Government should make it a priority to provide assistance to Afghan-led nongovernmental organizations, particularly Afghan women-led nonprofit organizations; and (4) grants and assistance to Afghanistan shall be conditioned upon the Government of Afghanistan adhering to international standards for women's rights and human rights. SEC. 4. ASSISTANCE TO WOMEN AND GIRLS. Section 103(a)(7) of the Afghan Freedom Support Act of 2002 (22 U.S.C. 7513(a)(7)) is amended-- (1) in subparagraph (A), by striking clauses (i) through (xii) and inserting the following: ``(i) to provide equipment, medical supplies, and other assistance to health care facilities for the purpose of reducing maternal and infant mortality and morbidity; ``(ii) to establish and expand programs to provide services to women and girls suffering from posttraumatic stress disorder, depression, and mental illness; ``(iii) to protect and provide services to vulnerable populations, including widows, orphans, and women head of households; ``(iv) to establish primary and secondary schools for girls that include mathematics, science, and languages in their primary curriculum; ``(v) to expand technical and vocational training programs to enable women to support themselves and their families; ``(vi) to maintain and expand adult literacy programs, including economic literacy programs that promote the well-being of women and their families; ``(vii) to provide special educational opportunities for girls whose schooling was ended by the Taliban and who now face obstacles to participating in the normal education system, such as girls who are now married and girls who are older than the normal age for their classes; ``(viii) to disseminate information throughout Afghanistan on the rights of women and on international standards for human rights; ``(ix) to provide information and assistance to enable women to exercise property, inheritance, and voting rights, and to ensure equal access to the judicial system; ``(x) to monitor and investigate violations of women's rights and to provide legal assistance to women who have suffered violations of their rights; ``(xi) to increase political and civil participation of women in all levels of society, including the criminal justice system; ``(xii) to provide information and training related to women's rights and human rights to military, police, and legal personnel; and ``(xiii) to provide assistance to the Ministry of Women's Affairs and the Independent Human Rights Commission for programs to advance the status of women.''; and (2) by restating subparagraph (B) to read as follows: ``(B) Availability of funds.--For each of the fiscal years 2007 through 2009-- ``(i) $5,000,000 is authorized to be appropriated to the President to be made available to the Afghan Ministry of Women's Affairs for the administration and conduct of its programs; ``(ii) $10,000,000 is authorized to be appropriated to the President to be made available to the Afghan Independent Human Rights Commission for the administration and conduct of its programs; and ``(iii) $30,000,000 is authorized to be appropriated to the President for grants to Afghan women-led nonprofit organizations to support activities including the construction, establishment, and operation of schools for married girls and girls' orphanages, vocational training for women and girls, health care clinics for women and children, programs to strengthen Afghan women-led organizations and women's leadership, and to provide monthly financial assistance to widows, orphans, and women head of households.''. SEC. 5. SENSE OF CONGRESS ON ASSISTANCE. It is the sense of Congress that, in providing assistance under section 103(a)(7) of the Afghan Freedom Support Act (22 U.S.C. 7513(a)(7)), as amended by section 4, the President should-- (1) condition the provision of such assistance on the recipient adhering to international standards for women's rights and human rights; and (2) ensure that Afghan women-led nongovernmental organizations throughout Afghanistan with demonstrated experience in delivering services to Afghan women and children receive grants without ethnic, religious, or any other discrimination. SEC. 6. REPORTING REQUIREMENT. (a) Reports Required.--Not later than 180 days after the date of the enactment of this Act, and every 6 months thereafter for 3 years, the Secretary of State and the Administrator of the United States Agency for International Development shall jointly submit a report on the activities carried out under this Act to the Committee on Foreign Relations and the Committee on Appropriations of the Senate and the Committee on International Relations and the Committee on Appropriations of the House of Representatives. (b) Content.--Each report submitted under subsection (a) shall include the amount of assistance provided under section 103(a)(7) of the Afghan Freedom Support Act of 2002 (22 U.S.C. 7513(a)(7)), as amended by section 4, to-- (1) the Afghan Ministry of Women's Affairs; (2) the Afghan Independent Human Rights Commission; and (3) Afghan women-led nonprofit organizations.

Afghan Women Empowerment Act of 2006 - Expresses the sense of Congress that the protection of the rights of women and girls in Afghanistan and their full participation in the reestablishment of democracy are essential to Afghanistan's reconstruction, and to achieve such reconstruction the U.S. government must commit resources to advance the rights of women throughout Afghanistan. Amends the Afghan Freedom Support Act of 2002 to revise the provisions respecting assistance to women and girls in Afghanistan. Extends funding authority. Expresses the sense of Congress that the President should: (1) condition the provision of such assistance on the recipient adhering to international standards for women's rights and human rights; and (2) ensure that Afghan women-led nongovernmental organizations with demonstrated experience in delivering services to Afghan women and children receive grants without ethnic, religious, or any other discrimination.

the experimental and theoretical studies of dilute magnetic semiconductors ( see , e.g. the recent review @xcite ) have revived the interest to details of reconstruction of the electronic structure of host materials induced by transition metal ions and concomitant defects . this interest stems from the fact that the simple vonsovskii - zener model of @xmath3-@xmath0 exchange is apparently not sufficient for an exhaustive explanation of the behavior of the most popular system ( ga , mn)as,@xcite not to mention the wide - gap materials like ( ga , mn)n , ( zn , co)o , ( ti , co)o@xmath4.@xcite not only the localized spin of magnetic ions but also the acceptor or donor - like states in the energy gap related to these ions are involved in the indirect exchange between the magnetic ions responsible for the long - range magnetic order . the nature of these states is the matter of a vivid discussion in the current literature . in particular , an isolated mn impurity in gaas creates a 0.11 ev acceptor level relative to the top of valence band . besides , the electrons in the half - filled @xmath5 shell form resonance levels in the middle of this band because of an anomalous stability of the half - filled 3d@xmath6 shell.@xcite since the substitution impurity mn@xmath7 is negatively charged relative to the host semiconductor , localizing a hole makes this defect neutral , and the binding energy of this hole is provided by the combined action of the coulomb potential , central cell substitution potential , hybridization and , maybe , @xmath3-@xmath0 exchange.@xcite at a high enough mn concentration , these acceptor levels form an impurity band and eventually merge with the hole states near the top of the valence band ( see ref . for a detailed discussion of the current experimental situation ) . according to the available calculations of the electronic spectra of an isolated cu in gap,@xcite the copper impurity should have a similar electronic structure . due to the special stability of the filled 3d@xmath8 shell all the 3d levels of the cu impurity are expected to be occupied in the ground state , and the electrical neutrality of cu impurity should be ensured by capturing two holes on cu - related acceptor levels close to the top of the valence band , so that the resulting electron configuration can be denoted as cu(d@xmath9 ) . indeed such acceptor states were found in cap : cu samples,@xcite although at that time the nature of these states remained unclear . recently , ferromagnetism with a high curie temperature in @xmath10-type cu - doped gap was detected.@xcite the epr signal of the cu@xmath11 state indicates that the 3@xmath0 shells of cu impurities are unfilled in this material in contradiction to the results of previous numerical calculations . this discrepancy gives us a motivation to revisit the problem . we present in this paper the results of numerical calculations of the electronic structure of cu - doped gap . two different computation schemes are used , which give mutually complementary information about the behavior of weakly and strongly doped materials . the first one is the conventional local density approximation ( lda ) scheme applied to the lattice of cu@xmath12ga@xmath1p supercells . similar methods were used for mn@xmath12ga@xmath1pn materials with pn = as , n , p.@xcite the second method is based on the local green function approach.@xcite in this method the hybridization between the local impurity @xmath0-orbitals and bloch waves in the host semiconductor is calculated exactly , without any kind of artificial periodic boundary conditions , and approximations are made only when taking into account the short - range part of substitution impurity potential . a green function calculation procedure based on the microscopic anderson model @xcite was proposed three decades ago @xcite and later on summarized in ref . . this procedure deals with the local green function @xmath13 the set @xmath14 includes both the electron states @xmath15 of the electrons localized in the d - shell of impurity atom and the states @xmath16 , which stand for `` the bloch tail '' of the impurity wave function . these states describe the distortion inserted by a substitution impurity in the spectrum of a host crystal . they are superpositions of the bloch waves , @xmath17 , where @xmath18 and @xmath19 are the wave vector and the band index respectively , @xmath20 is the spin quantum number . here @xmath21 is the index of the irreducible representation of the point group characterizing the symmetry of impurity and its surrounding , and @xmath22 denotes its row . therefore the function @xmath23 is diagonal in @xmath24 representation . the full hamiltonian @xmath25 includes the kinetic and potential energies of all electrons in the impurity atom and in the host crystal , as well as the coulomb and exchange interactions between these electrons . the projection procedure ( [ green ] ) is exact in principle , and the poles of the green function @xmath26 describe both continuous and localized impurity related states in the doped crystal . in the practical realization of this method some approximations are unavoidable . the main simplification , which we use here is the approximate treatment of the substitution potential @xmath27 where @xmath28 is the potential landscape for an electron in the host gallium atom in the site @xmath29 and @xmath30 is the self - consistent potential for the electrons in the @xmath5 shell of the cu ion substituting for ga in this site ( see section iii for detailed definition of these potentials ) . we suppose that this potential is localized within the defect cell of the doped crystal . the `` local substitution potential '' approximation influences only the description of @xmath10-type acceptor states in the lower part of the forbidden energy band . it ignores possible contribution of the coulomb component of substitution impurity potential . this contribution is known to be small in the case of ( mn , ga)as,@xcite and one may hope for a similar situation in ( cu , ga)p . the principal advantage of the local substitution potential is that in this case the system of dyson equations for the impurity - related components of the green function ( [ green ] ) defined as @xmath31 may be solved analytically @xcite . it yields the equation @xmath32 for the @xmath0-electron green function . the positions of electron @xmath0-levels @xmath33 are found self - consistently as a solution of the schrdinger equation for cu - related orbitals in the crystalline environment . the self energy in the right - hand side of eq . ( [ dgreen ] ) contains two contributions . the term @xmath34 describes the hybridization between the @xmath0-orbitals and the band electrons @xmath35 where the hybridization integral is @xmath36 the energy bands @xmath37 and bloch functions @xmath38 of the host gap crystal are calculated by means of the first principle full potential lapw method @xcite ( see section iii for details ) . the factor @xmath39 in eq . ( [ dgreen ] ) describes the short - range potential scattering , where @xmath40 is the substitution impurity potential localized in the defect shell , @xmath41 is the single - site lattice green function for the electrons in the non - doped host crystal described by the hamiltonian @xmath42 . as was shown in ref . , the green function ( [ dgreen ] ) describes the hybridization between the impurity @xmath0-electron orbitals and the electrons in the imperfect host crystal , where the band electrons are influenced by the potential scattering @xmath43 . if this scattering is strong enough , it results in splitting off of localized levels from the top of the valence band . this effect is also taken into account in ( [ dgreen ] ) : the positions of the corresponding levels before the hybridization are determined by zeros of the function @xmath44 in the energy gap of the host crystal . one of the fundamental statements of the theory of transition metal impurities in semiconductors @xcite is the necessity to discriminate between the impurity levels in the gap obtained as solutions of a self - consistent mean - field schrdinger equation for a doped crystal and the true addition / extraction energy of a @xmath0-electron to / from the valence / conduction band . the latter energies are determined by the energy balance of `` allen reactions''@xcite @xmath45 here @xmath46 is the total energy of doped crystal with the impurity having @xmath10 electrons in 3d shell . two allen reactions describe the electron transition from the top of the valence band @xmath47 to the empty neutral ( acceptor ) level and the electron transition from an occupied charged ( donor ) level to the bottom of the conduction band @xmath48 , so that the energies ( [ allen ] ) characterize the true positions of the impurity levels with respect to the band edges in the presence of strong coulomb and exchange interactions . these energies do not necessarily coincide with the mean - field solutions of the schrdinger equation due to the violation of koopmans theorem for the impurity ions . to minimize the mismatch between the single - electron and many - electron states , slater proposed a concept of `` transition state '' . according to his arguments , the ionization energy for a state with @xmath19 electrons in the 3d shell , @xmath49 may be approximated by the energy @xmath50 calculated within the lda single - electron calculation scheme . more refined lda+u approach @xcite takes non - koopmans corrections to the single - electron energies into account explicitly ( although still semi - phenomenologically ) . in terms of the allen energies ( [ allen ] ) , the energy @xmath51 is just the difference between @xmath52 and @xmath53 . we test below both the lda+u method of green function calculations and the standard lda supercell description of dilute ( gu , ga)p semiconductor . to realize a numerical version of the green function method we use the local density approximation ( lda ) and its modification lda+u , which takes into account strong electron - electron correlations on the impurity site . this section outlines the application of the lda+u method to systems with local defects with a particular emphasis on the transition metal impurities for which the resonant scattering in the d ( @xmath54 ) channel plays a crucial role . here we present only the principal features of the scheme leaving many more mathematical details and definitions in appendix . in this section we retain the spin index , having in mind to use the spin - unrestricted lsda+u version of this method for the calculation of spin properties of dilute magnetic semiconductors , although in the practical calculations below only the spin - independent lda+u version is used . the lda + u method incorporates a correction to the lda energy functional which provides an improved description of the electron correlations . the principal idea of the lda + u method is to separate the electron system into two subsystems of the localized @xmath0-electrons for which the coulomb interaction is accounted for by the hubbard repulsion term @xmath55 in the model hamiltonian whereas the delocalized @xmath3- and @xmath10-electrons are described by an orbital independent one electron potential @xmath56 . as a result the impurity green function ( [ green ] ) is defined by the dyson equation @xmath57\ ] ] where @xmath58 the green function ( [ dgreen ] ) is a solution of this equation . we work in the spherically symmetric local basis @xmath59 instead of cubic harmonics expansion @xmath60 used in ( [ dgreen ] ) . here @xmath10 is the index of repeating irreducible representations @xmath24 or @xmath61 , the analog of the principle quantum number @xmath19 in a spherical atom . the bare @xmath0-electron green function @xmath62 includes intraatomic correlations in the form of lda+u potential consisting of three terms , @xmath63 here the first term is the substitution lda potential @xmath64 the second term is the electron - electron interaction potential in the 3d shell , @xmath65\ ] ] and the last term is the double counting compensation potential , parametrized as @xmath66 here we introduced the occupational matrix @xmath67_{mm'}^{\sigma , pl } dz\ ] ] as a contour integral of the relevant matrix elements of the lda+u green function ( [ lda+u ] ) . the slater integrals@xcite in the atomic limit read @xmath68 where the coefficients @xmath69@xmath70 can be expressed in terms of the gaunt coefficients @xmath71 ( see appendix a.3 ) . the hybridization matrix elements ( [ hyb ] ) in the numerator of the mass operator now take the form @xmath72 here the bloch wave functions @xmath73 are calculated by means of the linearized augmented plane wave ( lapw ) method , @xmath74 is the vector connecting substitution impurity site taken as the point of origin with its nearest p neighbors in the zinc - blend lattice . in the impurity version of flapw method the defect site occupied by a cu ion is surrounded by the `` embedded sphere '' with the radius @xmath75 which includes the impurity sphere with the radius @xmath76 ( muffin - tin region , where the impurity potential is non - zero ) . muffin - tin spheres @xmath77 with a non - zero host lattice potential surround also the neighboring ga sites ( see fig . [ spheres ] ) . the impurity centered basis set is chosen as a set of the linear augmented spherical wave ( lasw ) functions [ see eqs . ( [ wf_1 ] ) , ( [ radial ] ) ] . in accordance with the lasw method , a set of bessel functions is used in the remaining part of the sphere @xmath75 . the wave functions in the two regions are matched by the standard boundary conditions imposed on the wave function and its derivative . the bloch functions @xmath78 of the host gap crystal outside the embedded sphere are obtained by the self - consistent flapw method . using the impurity centered local lasw functions we calculate the matrix elements of the host green function projected onto the local spin polarized lapw functions in the spherical interstitial site . after matching the boundary conditions ( see appendix ) , the matrix element ( [ matelem ] ) is transformed into @xmath79 ( @xmath80 stands for the vectors of reciprocal lattice , see appendix ) . as was mentioned above , substituting ga for a cu impurity results also in an appearance of a potential component of the impurity potential , which is taken into account approximately by adopting the koster - slater - like single site scattering approximation.@xcite then in accordance with eq . ( [ dyson ] ) , one may introduce the modified mass operator @xmath81 ( [ selfmod ] ) , where the zeros of the operator @xmath44 ( [ kosla ] ) determine the impurity states , which arise in the doped crystal due to the potential scattering only . the scattering amplitude @xmath82 is calculated by substituting the lapw wave functions @xmath83 for the bloch functions in eq . ( [ sub ] ) . as a result the equation for the deep level energy determined as a pole of the impurity green function ( [ dgreen ] ) within the framework of the lda+u technique reads @xmath84 it takes into account the resonance part of the scattering amplitude in the d ( @xmath54 ) channel and its mixing with the potential scattering states arising in the p ( @xmath85 ) channel . @xcite the adspace augmentation @xcite is used to represent the green function ( or resolvent ) @xmath86 for the gap crystal with a cu impurity in the matrix form , eq . ( [ augmgreen ] ) . the impurity augmented green function is subdivided into two blocks , of which the upper left corner block @xmath87 is constructed using the basis of @xmath88 orbitals where @xmath88 refer to the @xmath88-th state with the energy @xmath89 of the isolated adatom . the host is represented by the lower right corner block @xmath90 . it is worth emphasizing that such a direct introduction of the new adatom related states is very effective in the matrix formulation . since the high energy part of the spectrum of the differential operator is well suited for the description of the strongly localized @xmath0-type impurity states,@xcite the issue of the necessary number of the host crystal bands becomes crucially important . the direct introduction of the @xmath0-states drastically simplifies the problem . the dyson equation may be then split into two independently solvable equations ( see appendix ) which finally allows one to carry out the calculations of the gap host green @xmath91 using only 15 bands . the problem is treated self consistently , starting with the trial set of lapw functions obtained with the help of the impurity potential , which in the zero s approximation is just a sum of the atomic potentials of the defect crystal . the self - consistency procedure for @xmath92 is carried out in a mixed fashion . the first two iterations use the arithmetic average scheme , which later on is effectively substituted by the aitken scheme.@xcite just seven iterations produce the @xmath93 ry self - consistency . the equations presented in this section will be our working formulas for the lda+u calculations of the ga(cu)p compound where the cu atoms substituting ga host atoms will be considered as isolated impurities . a possible exchange interaction between the cu atoms and the resulting magnetic effects will be considered elsewhere . this section presents the results of calculation of the electronic structure of cu@xmath2ga@xmath1p obtained by means of the two methods , both using the lda approximation . the green function approach is based on the band structure calculated by means of the flapw method discussed in the previous section . the supercell approach uses the as - lmto method@xcite for the band calculations . the vosko@xcite and perdew - wang @xcite parametrization scheme is used for the calculation of the exchange - correlation potential in the former and latter approaches , respectively . brillouin zone ( bz ) integration is performed using the improved tetrahedron method.@xcite according to the present flapw and lmto calculations , the undoped gap is a semiconductor with the 1.83 ev flapw indirect gap and 1.61 ev asa - lmto gap between the top of the valence band ( vb ) at the @xmath94 point and the bottom of the conduction band ( cb ) at the ( 0,0,0.875 ) point close to the @xmath95 point of the fcc bz . a direct gap of 1.77 ev opens at the @xmath94 point . the 6.8 ev width valence band is formed by the strongly hybridized p @xmath10 and ga @xmath3 and @xmath10 states while the states at the top of vb in the vicinity of @xmath94 are formed by the p and ga @xmath10 states with a dominant contribution of the former . the band originating from the p related @xmath3 states hybridized with the ga related @xmath3 states is found between @xmath9612.5 and @xmath969.5 ev and separated by a gap of 2.8 ev from the bottom of the valence band . the density of states ( dos ) of gap is visualized in fig . [ gh ] as the imaginary part of the green function @xmath97 ( [ greenol ] ) calculated by the lapw method . and im@xmath98 for gap . ] a similar picture is obtained by direct band structure calculations within the asa - lmto method . the difference in the widths of the energy gaps only weakly influences the structure of the cu - related states in the energy spectrum of doped samples . we start the discussion of these states with a discussion of the supercell calculations . the electronic structure of cu@xmath2ga@xmath1p with @xmath100 varying from 0.125 down to @xmath1010.016 was calculated using @xmath102 , @xmath103 , and @xmath104 supercells of the cubic zinc - blend lattice . calculations for @xmath100=0.125 ( 1/8 ) , 0.063 ( 1/16 ) , and 0.031 ( 1/32 ) were performed for @xmath105 ( 216 ) fcc , @xmath106 bcc ( 217 ) , and @xmath107 ( 215 ) simple cubic unit cells , respectively . the face - centered cubic cells with @xmath108 and @xmath109 allowed to simulate compositions with @xmath110 ( 1/27 ) and @xmath111 ( 1/64 ) . in all the calculations the ga ion in the ( 0,0,0 ) position was substituted by the cu ion with the same atomic sphere radius . this way the tetrahedral ( @xmath112 ) symmetry of the cu impurity site was preserved . the positions of host atoms around the cu impurity were not relaxed . upon the cu substitution cu@xmath12ga@xmath1p becomes a metal with each cu impurity creating 2 holes in the valence band . at all the compositions @xmath100 studied in the present work the fermi level ( @xmath113 ) crosses the three bands which are triply degenerate at the highest energy in the @xmath94 point . at @xmath100=0.063 the top of the valence band lies 0.42 ev above @xmath113 and moves to 0.13 ev as the cu concentration decreases to @xmath100=0.016 . as an example , bands calculated along some high symmetry directions for cu@xmath12ga@xmath1p with @xmath100=0.031 are show in fig . [ fig : bnd32 ] . at this cu concentration the top of the valence band is situated 0.22 ev above @xmath113 . figure [ fig : dos32 ] ( lower panel ) shows the density of cu @xmath0 states in cu@xmath12ga@xmath114p with @xmath100 = 0.031 projected onto the irreducible representations @xmath115 and @xmath116 of the @xmath112 symmetry group . the densities of @xmath10 states of the nearest ( p@xmath117 and ga@xmath117 ) and next nearest ( p@xmath4 and ga@xmath4 ) neighbors of the cu impurity are presented in the middle and upper panels of fig . [ fig : dos32 ] . states ( lower panel ) and the density of p @xmath10 ( middle panel ) and ga @xmath10 ( upper panel ) states calculated for cu@xmath12ga@xmath1p with @xmath100=0.031 . ] the calculations show that the cu @xmath0 shell is almost completely filled and the cu valency is close to @xmath118 . cu @xmath0 states of @xmath115 symmetry ( @xmath119 and @xmath120 ) form a dos peak centered at @xmath1212.5 ev . they are completely occupied and do not contribute to the bands crossing the fermi level . the main peak of the density of the @xmath116 ( @xmath122 , @xmath123 , and @xmath124 ) states is located at @xmath125 ev . however , another two peaks of @xmath116 dos are clearly seen just at @xmath113 and @xmath126 ev below it . the origin of these peaks becomes more clear when the cu @xmath116 dos is compared to the density of @xmath10 states of the p@xmath117 ion closest to cu . the latter shows two prominent peaks exactly at the same energies . similar peaks can also be observed in ga@xmath117 dos as well as in dos of the more distant p and ga ions not shown in fig . [ fig : dos32 ] . an analysis of the partial occupations shows that of 2 holes ( @xmath127 ) created by the cu impurity only 0.18 @xmath127 is provided by the cu @xmath116 states . another 0.48 @xmath127 is distributed over the @xmath10 states of 4 @xmath128 ions whereas the remaining 1.36 @xmath127 is spread over more distant neighbors . it is worth noting that in spite of the appearance of the narrow dos peak exactly at @xmath113 the spin - polarized calculations failed to produce a ferromagnetic solution even for the highest cu concentrations studied . apparently , this can be explained by the delocalized character of the states responsible for the peak and an insufficient strength of the hund s exchange coupling for p and ga @xmath10 states , which give the dominant contribution to the corresponding bands . at the same time , the contribution of cu @xmath0 states , for which a strong on - site exchange interaction is expected , to the peak at @xmath113 is relatively small . we also performed test calculations for a few values of @xmath100 in @xmath129ga@xmath1p , in which a ga ion was substituted by a vacancy @xmath130 . a vacancy creates one more hole in the valence band as compared to cu . nevertheless , in the vicinity of the fermi level the band structures calculated for @xmath129ga@xmath114p are similar to those for cu - doped gap . in particular , the density of p@xmath117 states at and just below @xmath113 has the same two - peak shape . these peaks are also reflected in the density of @xmath130 @xmath0 states of the @xmath116 symmetry , however , they are much less pronounced than the corresponding peaks of cu @xmath116 dos . significantly higher peaks can be observed in the density of @xmath130 @xmath10 states which also transform according to the @xmath116 representation . thus , we may conclude that the bands crossing @xmath113 in cu@xmath12ga@xmath114p are mainly formed by the @xmath10 states of the nearest to the cu impurity p@xmath117 ions that split off from the top of the gap valence band as a result of breaking of the covalent p @xmath10 ga bonds at the impurity site . these states have @xmath116 symmetry and hybridize strongly with the corresponding cu @xmath0 states . these states are , however , rather extended , which leads to a relatively strong dispersion of the split - off bands even for @xmath100=0.016 . before turning to the calculation of the cu - impurity related levels in the host gap , let us look at the energy dependence of the self energy part ( [ massoper ] ) , which is responsible for the renormalization of @xmath5 levels due to the hybridization with the host band states . the hybridization matrix elements @xmath131 are calculated by means of eq . ( [ matelem ] ) using the cu 3@xmath0 impurity wave functions and lapw functions of the gap host . since the lapw wave functions are defined within the volume subdivided into two muffin - tin parts and the surrounding volume , the integration in eq . ( [ matelem ] ) is carried out in all three parts separately accounting for all the hybridization contributions as well as for the covalency induced non - spherical components of the difference potential . figure [ m ] represents the real and imaginary parts of @xmath132 obtained for the ( ga , cu)p compound . here index @xmath88 represents one of the components of the @xmath116 irreducible representation . comparison of @xmath133 with the density of band states which is shown as @xmath134 in fig . [ gh ] demonstrates that the weighting of the density of states with the squared hybridization matrix element reproduces the general shape and van hove singularities of the partial @xmath10-component of dos . the differences between @xmath135 and @xmath136 are more noticeable . both these functions are sums of the hilbert transforms of the dos and weighted dos for all the valence and conduction bands , respectively . therefore these function not only map the singularities of dos in the given band on the singularities of its hilbert transform but also accumulate asymptotic contributions of higher and lower bands at the given @xmath137 . this accumulation results in a noticeable smoothing of the @xmath138 function in the @xmath139 to 0 ev range . besides , weighting with @xmath140 strongly reduces the amplitude of @xmath141 in comparison with @xmath135 . such strong reduction means that the hybridization - induced renormalization of the atomic @xmath5 levels of the isolated cu impurity is small enough , and their positions are predetermined mainly by the impurity core potential and coulomb interaction within the muffin - tin sphere @xmath76 . for ( ga , cu)p . ] to compare the energy spectrum of the cu impurity in gap obtained by the green function method with that given by lda in the supercell calculation scheme , we first compute this spectrum by solving eq . ( [ resontscat ] ) within the lda scheme without the second term @xmath142 in the impurity potential ( [ dev ] ) . both the resonant and short range potential components of impurity scattering were taken into account . these calculations yield the value @xmath143 ev for the impurity @xmath144 resonance in the valence band , which is higher than that in the supercell calculation , and the @xmath145 peak lies slightly above this level . apparently , these peaks are related to the van hove singularities in the heavy hole band . these resonances are shallower than those seen in the supercell dos ( fig . [ fig : dos32 ] ) . as was mentioned above , the @xmath145 peak in the latter structure is located at @xmath146 ev . however , one should remember that the center of gravity of the valence band dos is shifted downward with respect to its position in the pure gap due to the transformation of @xmath145 and @xmath144 levels into @xmath0-bands ( see fig . [ fig : bnd32 ] ) . potential scattering built in the self energy part @xmath147 in eq . ( [ resontscat ] ) results in the appearance of an empty impurity level at @xmath148 ev . this acceptor level may be identified with the @xmath149 limit for the p related @xmath10-structure at the top of the valence band in the supercell dos ( fig . [ fig : dos32 ] , middle panel ) . the occupation of the impurity @xmath0-shell in this case is close to 10 , like in the supercell calculations . the computation of the impurity spectrum within the lda+u scheme yields a self - consistent solution for the electron spectrum only for the transition state 3d@xmath150 of cu impurity . this solution is described below . first , we determined the position of non - perturbed 3d - level of the cu atom and the correlation parameters @xmath151 . the isolated impurity energy @xmath152 ev is calculated by means of the semi - relativistic ratom program@xcite for the 3d@xmath150 configuration , which corresponds to the concept of the transition state adopted in this paper . the intraatomic coulomb repulsion of the @xmath0-electrons is treated in the lda + u approximation and @xmath153-dependent coulomb integrals ( [ slat ] ) are calculated . the choice of the parameters @xmath154 ev and @xmath155 ev is based on the analysis of the occupation numbers in the transition state approach.@xcite the self - consistent single electron 3@xmath0-level for the embedded cu impurity in the 3d@xmath150 configuration is in resonance with the valence band of gap host crystal , and the impurity - related resonance and discrete states are found as solutions of eq . ( [ resontscat ] ) . ) . the lowest of the five levels in the left panel correspond to the states @xmath156 , the next @xmath157 levels are classified as ( 2,-2),(2,0 ) and ( 2,+2 ) ( bottom - up ) . see the text for further discussion ] figure [ elstr ] depicts the electronic structure of ( ga , cu)p calculated by the green function method . we present here three versions of the calculations which account for : ( a ) resonant scattering , ( b ) short range potential scattering , and ( c ) combined case . in the resonant scattering approximation ( fig . [ elstr]a ) where the term @xmath158 is omitted in eq . ( [ resontscat ] ) , there are four occupied levels in the valence band and one empty level in the energy gap . the occupied states correspond to the configuration cu(@xmath159 of the impurity ion . these levels reflect the multiplet structure of this configuration . although we used the orbital quantum numbers in our computation procedure , the calculated electron density distribution reveals the @xmath112 point symmetry of the impurity surrounding . in terms of the corresponding cubic harmonics the lowest state has the @xmath116 symmetry , the two next levels belong to the @xmath115-representation , and the empty state in the energy gap is the @xmath116 state of the configuration @xmath160 . in terms of the allen diagrams ( [ allen ] ) these levels correspond to the addition energy @xmath161 and @xmath162 for @xmath144 and @xmath145 quantum numbers , respectively ( see similar classification for ( ga , ni)p in ref . ) . the final @xmath163 states belong to the @xmath164 and @xmath165 representations in the tanabe - sugano classification.@xcite the energy interval between the multiplet of occupied levels in the valence band and the empty level in the energy gap is @xmath166ev , which is comparable with the value of the input parameter @xmath167 ev . the hybridization renormalization due to the self energy @xmath168 in eq . ( [ resontscat ] ) is 0.115 ev for the occupied levels and 0.182 ev for the empty level . in the calculation procedure described above , the difference in hybridization shifts for @xmath116 and @xmath115-levels was neglected , because the hybridization ( ligand field ) contribution is small enough for the cu impurity ion . figure [ elstr]b exhibits the net contribution of potential scattering ( [ dev1 ] ) to the formation of impurity - related states . the levels shown in this figure are obtained from ( [ resontscat ] ) with @xmath169 substituted for @xmath170 [ see eq . ( [ selfmod ] ) ] . the states in the occupied part of the spectrum are the impurity resonances in the valence bands around the maxima of the partial @xmath10-wave contributions at the energies @xmath171ev and @xmath172ev ( cf . figs . [ fig : dos32 ] and [ m ] ) . the @xmath10-level arises at the energy @xmath173ev above the top of the valence band . both the @xmath0- and @xmath10-like states are found in the solution of eq . ( [ resontscat ] ) with the full self energy @xmath174 ( fig . [ m]c ) . the most significant difference between the combined spectrum of fig . [ m]c and those of fig . [ m]a , b is the noticeable hybridization between @xmath10 and @xmath144 resonances in the valence band , whereas thee @xmath145 levels are only slightly shifted . the shallow @xmath10-level in the energy gap is pinned to its original position shown in fig . [ m]b , in spite of @xmath175 hybridization . all these results agree with qualitative predictions of the analytical model taking into account both resonant and short - range potential stattering.@xcite there is no straightforward way to compare the results of lda+u calculations with those obtained within the lda scheme , since the former method uses the fitting parameters @xmath176 , whereas the latter one is based on the variational approach , which formally gives the solution corresponding to the minimal total energy . we only may estimate the total energies of the two solutions by comparing the positions of the impurity levels obtained by both methods within the same green function approach . lda procedure gives the occupied @xmath115 and @xmath116 levels at the energies @xmath177 to 0.66 ev below the top of the valence band and the shallow @xmath10-level at the energy @xmath148 ev , which corresponds to the configuration @xmath178 : two holes neutralize the excess charge in the @xmath0 shell , which means that the triply degenerate @xmath10-level is occupied by one electron . in the lda+u solution the occupied @xmath116 and @xmath115-levels lie essentially deeper in the valence band at the energies @xmath179 to 1.8 ev , cu ion behaves as the isoelectronic impurity @xmath180 , and the acceptor @xmath10-levels are triply occupied in the neutral impurity state . the comparison of single - electron energies for the two solutions gives the energy gain @xmath181 ev for the latter state . it is hardly probable that the exchange - correlation contribution may change the energy balance in favor of a state with the fully occupied 3@xmath0 shell of the cu impurity . comparing the electronic structures of ( ga , cu)p obtained by the supercell and green function methods , one may indicate both similarities and dissimilarities in the description of impurity - related states . first , both methods provide the same mechanism for formation of the shallow @xmath10-levels in the energy gap of the host material , which merge into the impurity band at a high enough dopant concentration . these levels are split off from the top of the valence band and partially hybridized with the @xmath116 levels in the valence band . second , the spectral density of the impurity related @xmath182-states is concentrated mainly in the valence band with the @xmath144 component lying below the @xmath145 component . here , however , the important difference between the two approaches should be emphasized . as was mentioned above , the @xmath182 resonances calculated within the green function lda approximation are shallower than those found by means of the supercell approach . one may see also a difference in the @xmath183 splitting : it can be estimated as @xmath184ev in the supercell calculations and as @xmath185ev in the green function calculations . the main reason of this difference is the fact that the impurity @xmath5-levels are transformed in an effective @xmath0-bands in the periodic supercell structure , and the hybridization repulsion between the two bloch waves is stronger than that between the localized @xmath0-levels and periodic partial @xmath10-waves in the green function approach . the same argument is valid for the quasiband method used in the calculations of ref . , where the cu - related @xmath0 - levels are located even deeper than in our supercell calculations at the energies @xmath186 ev below the top of the valence band of gap . the most important difference between the results described in subsections iva and ivb is of course the difference in the electron configuration of cu impurity , which is @xmath178 in the supercell calculations and @xmath187 in the green function calculations . available experimental data @xcite are in favor of the configuration @xmath188 . at this stage we have no exhaustive explanation of these discrepancies . first , our scheme should be extended to the spin - unrestricted lsda solution and to the multiimpurity case . we expect that the charge configuration of cu ions is highly sensitive both to the spin state and to the interimpurity coupling . second , more experimental investigations are necessary , which would reveal the role of concomitant defects , the annealing conditions , the thickness of the film and other technological factors . it is also worthwhile checking whether the use of lda+u method in the supercell approach may result in the configuration with an incomplete @xmath5 shell of the cu impurity . we leave all these questions for further investigations . the numerical solution of the dyson equation ( [ resontscat ] ) derived by means of the green function method reveals similarities and dissimilarities between the electronic structures of the mn impurity ( half - filled 3@xmath0 shell in atomic state ) and cu impurity ( completely filled 3d shell in atomic state ) substituting for ga in zinc blende semiconductor . our calculations show that unlike mn , which retains its stable half - filled 3d@xmath6 shell in the host gaas and gap crystals,@xcite the cu impurity may release some of its @xmath0-electrons from the stable filled shell 3d@xmath8 to minimize the total energy of doped crystal , at least in the wide - gap gap . our theoretical result partially agrees with the experimental observation of cu ions with unfilled 3d shell in gap.@xcite it paves a way to theoretical explanation of the ferromagnetic ordering in ga@xmath1cu@xmath2p crystals , although for this purpose further development of the green function method is necessary . the results of the numerical study of magnetic ordering by means of the green function method will be published elsewhere . this work is partially supported by the max - planck gesellschaft during the stay of o.f . , k.k . and v.f . in mpipks ( dresden ) , where this work was completed . in order to realize the gf approach in a computational scheme we make use of the local density approach ( lda)@xcite and its lda+u modification @xcite which accounts for a strong electron - electron interaction . the approximation @xcite is used for the exchange - correlation potential . the band structure of the gap semiconductor is calculated by means of the ab - initio full potential all electrons lapw method.@xcite this method presents the charge density and the crystal potential as a series of the spherical harmonics inside the muffin - tin spheres and of the plane waves outside the spheres . the self - consistent electronic band structure is determined by solving a single particle dirac equation by using the variational method in lapw - function basis \{@xmath189}. in order to evaluate the coulomb part of the crystal potential we use the concept of multipole potentials and solve the dirichlet problem for the sphere with all the contributions being treated on equal footing.@xcite the exchange - correlation potential is approximated by the pad approximant technique in order to interpolate accurately the recent monte carlo results with the rpa spin - dependent data.@xcite the fourier components of the exchange - correlation potential in the interstitial region are fitted in the least square method by applying the singular value decomposition procedure . the charge density in the interstitial region is calculated in ca . 2000 to 3000 random points in the irreducible wedge of the wigner - seitz cell . in order to find the self energy @xmath190 , one has to calculate the matrix elements @xmath191 between the band states @xmath192 and the states @xmath193 is developed for this sake . here @xmath194 is the impurity green function , whereas the host crystal is represented by @xmath195 the wave functions of electrons localized in the impurity 3@xmath0 shell are defined within the impurity sphere @xmath196 ( see fig . [ spheres ] ) : @xmath197 . the radial parts of these functions are defined as solutions of the equation @xmath198r_{pl}(r ) = \varepsilon_{pl } r_{pl}(r),\ ] ] and the angular parts are represented by the spherical harmonics . the bloch wave functions are expanded in the reciprocal wave vectors @xmath199 @xmath200 where with @xmath202@xmath203 y_{lm}(\widehat{\mbox{\boldmath$\rho$}}).\ ] ] the following notations has been used above : @xmath204 @xmath205 @xmath206 are eigenvectors of lapw variation procedure ; @xmath19 is the number of the accounted energy bands , @xmath207 is the volume of the wigner - seitz cell , @xmath208 and @xmath209 are the muffin - tin coefficients in the lapw method , and @xmath210 for the fixed energy @xmath211 . @xmath212 is the radial part of the lapw function . calculations of the electronic structure of defects in crystals are usually based on the pseudopotential or lcao + pseudopotential approach@xcite . this method requires a large number of the gaussian orbitals and calculation of their overlap integrals . instead we perform here an all - electron calculation which allows one to realize the spin - polarization lda + u scheme . this approach uses the basic set of @xmath213 functions @xmath214 here @xmath215 is a non - negative quantum number and @xmath216 , the inverse length @xmath217 is defined by zeros of the bessel function @xmath218 for the radius @xmath219 of the embedded sphere ; @xmath10 is the integer number enumerating these zeros . the radial part of the wave function ( [ wf_1 ] ) is @xmath220 here the parameters @xmath221 @xmath222 are used to match the function ( [ radial ] ) to the bessel functions outside the muffin - tin region , @xmath223 , @xmath224 , @xmath225 . the above basis @xmath226 was used in the cholesky decomposition @xmath227 for the overlap matrix @xmath228 in order to obtain the orthonormal basis @xmath229 then the green function of the host crystal is projected onto the localized basis @xmath230 and calculated by means of the analytical tetrahedron method @xcite within the irreducible part of the brillouin zone ( _ ibz _ ) @xmath231 here @xmath232 the coefficients @xmath233 depend only on the dispersion relation @xmath37 and can be computed only once . the impurity green function ( [ dyson ] ) contains several self energy corrections to the atomic levels @xmath234 . two of them given by eqs . ( [ dev2]),([dev3 ] ) arising from the coulomb interaction are responsible for the multiplet structure of the energy levels , potential contribution ( [ dev1 ] ) results in the crystal field splitting of these levels , and the resonance self energy ( [ selfmod ] ) is the analog of ligand field correction in conventional theory of transition metal impurities.@xcite this section discusses the calculation of the two last terms within the green function formalism . the resolvent operator @xmath235 and the corresponding density variation @xmath236 is calculated both for the host block [ @xmath237 , @xmath236 ] and for impurity block [ @xmath239 , @xmath240 of the secular matrix ( [ augmgreen ] ) . when calculating the contour integrals resulting in ( [ deltarho_1 ] ) we use semi - circular contour from the bottom of the valence band @xmath241 to the fermi energy @xmath113 . the charge dependent difference potential @xmath92 is not necessarily spherically symmetric . we define the substitution impurity potential as the difference @xmath242 = v_{eff}[\rho({\bf r } ) ] - v_h^0[\rho_h^0({\bf r})]\ ] ] between the true self - consistent effective potential @xmath243 $ ] and the effective self - consistent potential @xmath244 $ ] of the host crystal , both taken in the lda approximation . here @xmath245 and @xmath246 are the respective electron densities . the impurity correction to the host green function of the crystal induced by the potential ( [ dev1 ] ) @xmath247 is found from the corresponding dyson equation@xcite @xmath248 \widetilde { \textsf g}_h^0(z).\ ] ] here @xmath249 \chi_\nu({\bf r } ) d{\bf r}\ ] ] and @xmath250 is a unit matrix . the density variation is calculated using the equation @xmath251 where @xmath252 and @xmath253 the lower integration limit @xmath241 is chosen to include all the relevant band and impurity states , @xmath113 is the fermi energy . to compute the integral ( [ deltarho_1 ] ) , we introduce the contour @xmath254 in the complex plane @xmath255 enclosing all the poles up of the green function up to the fermi energy in the charge density integration . with @xmath256 calculated by means of eqs . ( [ deltarho ] ) and ( [ deltarho_1 ] ) we calculate anew the charge dependent impurity potential @xmath257 in the `` embedded cavity '' , which is not spherically symmetric . the density variation can be similarly represented as @xmath258 where one readily obtains @xmath259 with next we separate the impurity and host parts in the density correction @xmath262 where @xmath263 is the host contribution , and @xmath264 is the substitution impurity contribution . the functions @xmath265 are the radial parts of the impurity centered local orbitals ( [ phid ] ) self energy correction @xmath268 in ( [ selfmod ] ) contains the matrix elements ( [ matelem ] ) . after substituting the potential ( [ sub-1 ] ) in the integral ( [ matelem ] ) and matching the boundary conditions in accordance with the procedure described above , the hybridization matrix element acquires the form ( [ matelspher ] ) . 99 t. jungwirth , j. sinova , j. masek , j. kucera , and a.h . macdonald , rev . phys . * 78 * , 809 ( 2006 ) . r. bouzerar , g. bouzerar , and t. ziman , phys . b * 73 * , 024411 ( 2006 ) . m. strassburg , m.h . kane , a. asghar , q. song , z.j . zhang , j. senawiratne , m. alevi , n. dietz , c.j . summers , and i.t . ferguson , j. phys . : condens . matter * 18 * , 2615 ( 2006 ) . coey , m. venkatesan , and c.b . fitzgerald , nature materials * 4 * , 173 ( 2005 ) . griffin , a.b . pakhomov , c.m . wang , s.m . heald , and k.m . krishnan , j. appl . * 97 * , 10d320 ( 2005 ) ; phys . * 94 * , 157204 ( 2005 ) . a. zunger in _ solid state physics _ , edited by f. seitz and d. turnbull ( academic press , new york , 1986 ) , vol . 39 , p. 275 . kikoin and v.n . fleurov , _ transition metal impurities in semiconductors _ ( world scientific , singapore , 1994 ) . bhattacharjee , c. benoit la guillaume , solid st . 113 * , 17 ( 2000 ) p.m. krstaji , f.m . peeters , v.a . ivanov , v. fleurov and k. kikoin , phys . b * 70 * , 195215 ( 2004 ) t. jungwirth , j. sinova , a.h . macdonald , b.l . gallagher , v. novk , k.w . edmonds , a.w . rushforth , r.p . campion , c.t . foxon , l. eaves , k. olejnk , j. maek , s .- r . e. yang , j. wunderlich , c. gould , l.w . molenkamp , t. dietl , and h. ohno , phys . b * 76 * , 125206 ( 2007 ) v.a . singh and a. zunger , phys . b * 31 * , 3729 ( 1985 ) l .- . ledebo and b.k . ridley , j. phys . c : solid state phys . * 15 * , l961 ( 1982 ) a. gupta , f.j . owens , k.v . rao , z. iqbal , j.m . osorio guille , and a. ahuja , phys . b * 74 * , 224449 ( 2006 ) ; f.j . owens , a. gupta , k.v . rao , z. iqbal , j.m . osorio guille , a. ahuja , and j .- h . guo , ieee trans . magn . * 43 * , 3043 ( 2007 ) . shick , j. kudrnovsk , v. drchal , phys . b * 69 * , 125207 ( 2004 ) . l. kronik , m. jain , and j.r . chelikowsky , appl . * 85 * , 2014 ( 2004 ) . v.n . fleurov and k.a . kikoin , j. phys . c * 19 * , 887 ( 1986 ) . anderson , phys . rev . * 124 * , 41 ( 1961 ) . v.n . fleurov and k.a . kikoin , j. phys . c : solid state phys . * 9 * , 1673 ( 1976 ) . haldane and p.w . anderson , phys . b * 13 * , 2553 ( 1976 ) . mattheiss and d.r . hamann , phys . b * 33 * , 823 ( 1986 ) . farberovich , s.v . vlasov , k.i . portnoi , and a.yu . lozovoi , physica b * 182 * , 267 ( 1992 ) . allen _ in _ proc . physics of semiconductors ( paris , dunod , 1964 ) , p. 781 . anisimov and j. zaanen , o.k . andersen , phys . b * 44 * , 943 ( 1991 ) . solovyev , p.h . dederichs , v.i . anisimov , phys . b * 50 * , 16861 ( 1994 ) . czyzyk and g.a . sawatzky , phys . * , 14211 ( 1994 ) . williams , p.j . feibelman and n.d . lang , phys . , b*26 * , 5433 ( 1982 ) . u. lindefelt and a. zunger , phys . , b*26 * , 846 ( 1982 ) . aitken , proc . edinburgh , 46 , 289 ( 1926 ) . williams , j.kubler , c.d . gelatt , phys . , b*19 * , 6094 ( 1979 ) . vosko , l. wilk , and m. nussiar , can . j. phys . , * 58 * , 1200 ( 1980 ) . perdew and y. wang , phys . , b*45 * , 13244 ( 1992 ) . p. lambin and j.p . vigneron , phys . , b*29 * , 3430 ( 1992 ) ; p.e . blchl , o. jepsen , and o. k. andersen , phys . , b*49 * , 16223 ( 1995 ) . farberovich , s.v . vlasov , and g.p . nizhnikova , _ program of the self - consistent relativistic calculation of the atomic and ionic structures in lsda approximation _ , viniti no . 2953 - 83 ( 1983 ) ( russia ) . k. sato , p.h . dederichs , h. katayama - yoshida and j. kudrnovsky , j. phys . : condens . matter . , * 16 * , s5491 ( 2004 ) . c. timm and a.h . macdonald , phys . b * 71 * , 155206 ( 2005 ) o.v . farberovich , _ electronic structure and physical properties of compounds with d- and f - metals _ , ph.d . thesis , voronezh university ( russia ) , 1984 . anisimov , i.v . solovyev , m.a . korotin , m.t . czyzyk , and g.a . sawatzky , phys . b*48 * , 16929 ( 1993 ) . h. katayama - yoshida and a.zunger , phys . , b*31 * , 7877 ( 1985 ) . j. bernholc , n.o.lipari and s.t . pantelides , phys . * 41 * , 895 ( 1978 ) .

a numerical method for calculation of the electronic structure of transition metal impurities in semiconductors based on the green function technique is developed . the electronic structure of 3@xmath0 impurity is calculated within the lda+u version of density functional method , whereas the host electron green function is calculated by using the linearized augmented plane wave expansion . the method is applied to the cu impurity in gap . the results of calculations are compared with those obtained within the supercell lda procedure . it is shown that in the green function approach cu impurity has an unfilled 3d shell . this result paves a way to explanation of the magnetic order in dilute ga@xmath1cu@xmath2p alloys .

stress induced hyperglycemia is a known complication of neonatal sepsis , but sometimes it may become very difficult to distinguish it from neonatal diabetes mellitus . we present a case of neonatal septicemia with stress induced hyperglycemia mimicking neonatal diabetes mellitus . extremely high blood sugar values with metabolic acidosis were noted in a term good weight baby caused a diagnostic dilemma . the present case report is about a 3 kg term neonate who presented on the 9 day of life with a history of fever for 2 days , lethargy and one episode of seizure . at admission , he was in a state of shock with severe dehydration . he was given two boluses of normal saline , radiant warmer care and intravenous antibiotics ( cefotaxime and vancomycin ) were started . the blood sugar was 1529 mg / dl and arterial blood gases revealed mild metabolic acidosis ( ph - 7.289 and hco3 - 11.5 ) . dehydration was corrected and thereafter considering the high blood sugar , the child was started on intravenous insulin infusion promptly at a dose of 0.1 iu / kg / h . on evaluation , there was thrombocytopenia ( platelet count-25,000 ) and serum procalcitonin was 3.10 ng / ml and c - reactive protein was 10 , which was high and suggestive of septicemia . lumbar puncture revealed a turbid cerebrospinal fluid ( csf ) , which was full of polymorphonuclear cells , csf protein was 80 mg / dl and sugar was 67 mg / dl . hence , a diagnosis of late onset neonatal septicemia with shock with stress induced hyperglycemia was considered . considering neonatal diabetes as another possibility due to very high blood sugars , child was evaluated further and it was found that serum insulin and glucagon stimulated c peptide levels were respectively 4.00 mcu / ml and 2.57 ng / ml , which were normal . child improved as acidosis and hyperglycemia gradually resolved , there were no more seizures and urine output was adequate . insulin infusion was slowly tapered as blood sugar normalized and it was stopped after 48 h. child maintained normoglycemia hereafter and did not require insulin infusion any more . magnetic resonance imaging brain was done at 45 days of life which revealed cerebral venous thrombosis of the transverse sinus with hemorrhagic infarct in left temporal region [ figure 1 ] . the child has been under follow - up for 6 months now with normoglycemia and no neurological sequelae . ( a ) axial t2 fluid attenuation inversion recovery image showing hemorrhagic infarct in left temporal region . ( b ) axial contrast - enhanced t1 image showing thrombus in the left transverse sinus hyperglycemia , defined as fasting blood glucose > 125 mg / dl is mostly seen in very low birth , small for gestation age infants and preterm babies receiving intravenous glucose infusion . this is attributable to altered metabolism associated with immaturity , as well as the need for continuous parenteral nutrition . in these children , it may be triggered by respiratory distress , surgery , neonatal pain , sepsis and other stressful events . hyperglycemia in preterm infants has been associated with increased rates of death , intraventricular hemorrhage ( ivh ) , sepsis and retinopathy of prematurity and with increased lengths of hospital stay . the problem of hyperglycemia is manifested due to an increase in the osmolality ( 1 mosm / l rise is noted with every 18 mg / dl increase in blood sugar ) ; particularly beyond 300 mosm / l . this is in the form of electrolyte disturbances , osmotic diuresis and in extreme form with ivh . the study by louik et al . had discussed that the fluctuations in cerebral blood flow velocity markedly increase the risk of ivh and such fluctuations may be partially caused by rapid change in osmolality . whether hyperglycemia causes ivh or vice versa is still controversial , but a plasma glucose level of more than 300 mg / dl is usually associated with a high risk of developing ivh . however , there is a paucity of data in indian population where more than 30% babies are low birth weight . in a study carried out on 1171 newborns admitted to nicu by chellani et al . , the mean blood glucose level was 271.8 75.33 mg / dl ( range : 175 - 400 mg / dl ) with a mean duration of hyperglycemia 60.6 15.44 h ( range : 48 - 96 h ) . in our case values as high as 1529 mg / dl were noted , which is uncommonly seen in term babies who are non - diabetic . stress factor responsible for causation of hyperglycemia includes sepsis due to escherichia coli and group b streptococci . it can also be associated with hyperglycemia by catecholamine , cortisol influences on the mobilization of glycogen , gluconeogenesis and insulin response . on the other hand , endotoxins and cytokines methyl - xanthine which is most often used in preterm babies causes an increase in camp level resulting in activated liver glycogenolsis . as per the cochrane database , it is possible that it is the sicker neonate , who is at higher risk for adverse clinical outcomes , who is more prone to hyperglycemia because of stress or metabolic injury to vital organs , especially the brain . it is also possible that it is hyperglycemia per se that is a cause of adverse clinical outcomes , especially if hyperglycemia is severe enough to cause significant plasma hyperosmolality resulting in fluid shifts from the intracellular to the extracellular fluid compartment . there is also some evidence of an adverse effect of severe hyperglycemia on neurologic outcome following cerebral ischemia in animals and adult humans as well as the neonate . thus , in the very low birth weight / extremely low birth weight neonate with hyperglycemia , it is important to determine the benefits and risks of treating the hyperglycemia by either reducing the rate of glucose infusion or by administering exogenous insulin . based on the above report it can be concluded that stress due to sepsis induced transient hyperglycemia in the newborn may present with extremely high blood sugar values and may mimic neonatal diabetes mellitus . it can be seen even in term babies , contrary to the belief that it occurs in preterm and small for gestation babies . considering the prognostic implications it may cause it is important that hyperglycemia is promptly treated by insulin infusion .

stress / sepsis induced transient hyperglycemia in the newborn may present with extremely high blood sugar values and may mimic neonatal diabetes mellitus . we present a case of neonatal septicemia with stress induced hyperglycemia mimicking neonatal diabetes mellitus . extremely high blood sugar values upto 1529 mg / dl with metabolic acidosis were noted in a term good weight baby causing a diagnostic dilemma . it can be seen even in term babies , contrary to the belief that it occurs in preterm and small for gestation babies . considering the prognostic implications it may cause it is important that hyperglycemia is promptly treated by insulin infusion .

Media playback is unsupported on your device Media caption Barbara Plett-Usher explains what the UN Security Council's vote means The United Nations Security Council has passed a resolution urging an end to illegal Israeli settlements after the US refused to veto it. The Egyptian-drafted resolution had been withdrawn after Israel asked Donald Trump to intervene but it was proposed again by Malaysia, New Zealand, Senegal and Venezuela. The US has traditionally sheltered Israel from condemnatory resolutions. Israeli PM Benjamin Netanyahu said he would not abide by the vote. Israel announced its ambassadors to New Zealand and Senegal had been ordered to return for consultations. Israel has no diplomatic ties with Malaysia and Venezuela. The Palestinian leadership welcomed the UN resolution, which was passed by 14 votes to zero, with one abstention. President-elect Trump, who will be inaugurated on 20 January, tweeted after the vote: "As to the UN, things will be different after Jan. 20th." The issue of Jewish settlements is one of the most contentious between Israel and the Palestinians, who see them as an obstacle to peace. About 500,000 Jews live in about 140 settlements built since Israel's 1967 occupation of the West Bank and East Jerusalem. The settlements are considered illegal under international law, though Israel disputes this. Blame and bitterness keeping peace at bay US policy reverse: By Barbara Plett Usher The resolution reflects an international consensus that the growth of Israeli settlement-building has come to threaten the viability of a Palestinian state in any future peace deal. It is a view strongly shared by the Obama administration, and for that reason the US reversed its policy of vetoing any UN Security Council criticism of Israel. It is a decision that was taken after months of debate within the administration about whether and how President Obama might be able to define his position on a two-state solution before leaving office. But his successor Donald Trump has made clear he intends to strongly support Israeli government positions, even making a highly unorthodox intervention before the vote by publicly urging Mr Obama to veto the resolution. In a statement, Israeli Prime Minister Benjamin Netanyahu's office said: "Israel rejects this shameful anti-Israel resolution at the UN and will not abide by its terms. "At a time when the Security Council does nothing to stop the slaughter of half a million people in Syria, it disgracefully gangs up on the one true democracy in the Middle East, Israel, and calls the Western Wall 'occupied territory'. "The Obama administration not only failed to protect Israel against this gang-up at the UN, it colluded with it behind the scenes. Israel looks forward to working with President-elect Trump and with all our friends in Congress, Republicans and Democrats alike, to negate the harmful effects of this absurd resolution." Image copyright AFP Image caption Donald Trump has taken a strongly pro-Israel stance The US ambassador to the UN, Samantha Power, said the resolution reflected the "facts on the ground" that settlement growth had been accelerating. "The settlement problem has gotten so much worse that it is threatening the two-state solution," she said. She criticised Mr Netanyahu's support for settlement expansion, saying: "One cannot simultaneously champion expanding settlements and champion a two-state solution that would end the conflict." However, Ms Power added that the US had not voted in favour of the resolution because it was "too narrowly focused" on settlements. She added that even if all settlements were dismantled, both sides would still have to acknowledge "uncomfortable truths" and make "difficult choices" to reach peace. A spokesman for Palestinian President Mahmoud Abbas said: "The Security Council resolution is a big blow to Israeli policy, a unanimous international condemnation of settlements and a strong support for the two-state solution." On Thursday, Mr Trump had urged the Security Council to defeat the motion. "Peace between the Israelis and the Palestinians will only come through direct negotiations between the parties, and not through the imposition of terms by the United Nations," he said in a statement. "This puts Israel in a very poor negotiating position and is extremely unfair to all Israelis." ||||| The Security Council is expected to vote today on a resolution, introduced by Egypt, condemning the presence of settlements — Jewish communities in the West Bank and eastern Jerusalem. For years, there has been mounting speculation, fueled by the administration itself, that President Obama would use his lame-duck period in office for a major anti-Israel action, probably by not providing the customary U.S. veto to such resolutions. I expect the United States will veto today’s resolution, but that may be only a prequel to allowing the passage of one of the numerous similar resolutions that have been floated. The other resolutions are substantively similar, but unlike the Egyptian proposal, they may make cosmetic, inconsequential half-criticisms of Palestinian Authority “incitement” (while ignoring the PA’s ongoing solicitation and sponsorship of actual killings of Jews). Then the administration would then say it vetoed “anti-Israel resolutions,” but simply could not hold back the tide against a “balanced” resolution. Obama’s goal with such a resolution would be to punish Israeli Prime Minister Benjamin Netanyahu, whom he personally dislikes, and to create diplomatic facts on the ground to box in President-elect Donald Trump’s foreign policy. The folly of a such resolution has been underscored by both Hillary Clinton and Trump, as well as near-unanimous majorities in both houses of Congress and an array of Democratic foreign policy experts, including former Senate majority leader and Obama administration peace negotiator George Mitchell. Such a resolution would not cement any positive legacy for Obama. To the contrary, it would vastly magnify the actual obstacles to resolving the Palestinian issue. Moreover, by setting the U.N. against Israel, Obama may provoke a sharp conflict between Washington and the U.N. — one that would harm the latter much more than the former. The proposed resolution denounces any Jewish presence in eastern Jerusalem and the West Bank as illegal and demands that Israel immediately choke off such communities. These areas had been entirely cleansed of their ancient Jewish populations during the Jordanian invasion and occupation in 1949. The standard diplomatic position of the U.N. is that Israel, upon retaking these areas in 1967, was obligated to indefinitely forbid Jews from living in these areas (but the U.N. has amazingly avoided applying these supposed rules anywhere else). The legal effects of such a resolution would be murky — the Security Council is neither a court nor a legislature and cannot create rules of international law. Nor do the resolutions invoke the council’s power under Chapter 7 of the U.N. Charter to call for mandatory measures, such as sanctions. What is clear is that a Security Council resolution will reinforce all the dynamics that have made a solution more remote despite eight years of pressure on Israel by Obama. 1. Showing the Palestinians the outside option is better. The resolution would teach the Palestinians that appealing to the international community will always give them a better offer than negotiations — since unlike Israel, the international community asks nothing of the Palestinians in return. Such a process can never lead to peace, as it takes none of Israel’s interests into consideration. A Security Council resolution would only entrench Palestinian maximalism and refusal to negotiate. Indeed, this is exactly what the U.S. ambassador to the U.N., Susan Rice, said when vetoing a similar resolution in 2011. 2. No penalty for refusal. The Palestinians have been offered an independent state in the peace negotiations in 2000 and 2001, and apparently Netanyahu was prepared to make far-reaching concessions in 2014. Each time, the Palestinians said no. Never has there been a national independence movement that has refused an independence offer on the grounds that it does not include all the territory the movement seeks. Imagine if the United States refused to accept peace with Britain because it did not give the newly independent colonies the northern border they sought. Yet the Palestinian rejection of successive proposals carries no negative consequences for them — it just raises the expectations from Israel in the next round. Similarly, the Palestinians will not fully accept whatever the Security Council gives them, but only use it as a basis for further demands. 3. Undermining U.S. credibility as a player in the Middle East peace process. U.S. credibility will be damaged by effectively overturning prior American commitments to Israel, such as not requiring a full withdrawal from the West Bank, accepting the settlement blocs and insisting that any core issues be resolved only through “direct negotiations between the parties,” rather than U.N. “shortcuts,” as the Obama administration said in 2011. For these understandings, Israel made concrete and dramatic concessions, from the Oslo process that created the Palestinian Authority and gave it broad territory, to the Gaza withdrawal, which created a Hamas terror state. Discarding these understandings will give Israel no reason to think that future concessions will not lead to empty promises as well. Moreover, such a resolution effort in the last weeks of the Obama administration would almost certainly prompt Trump to compensate strongly, re-creating the diplomatic space Obama took away. With Republican control of Congress and the White House, the avenues for pushback would be many. Trump could make an anti-settlements resolution a dead letter by moving the U.S. Embassy not just to Jerusalem, but to eastern Jerusalem. This would be consistent with his platform of an “indivisible” Jerusalem and with federal law that treats the entire “united” city as a proper site for the embassy. Trump’s State Department could issue an opinion that settlements are indeed legal; he could provide incentives for U.S. companies doing business with Israeli settlements. To paraphrase David Ben Gurion, it is not what the U.N. says but what the U.S. does that will ultimately shape reality. But Trump’s reaction will likely be broader than simply doubling down on any pro-Israel moves he may be contemplating. The cynical use of the U.N. to bypass U.S. electoral outcomes and constrain the next president’s policy could lead to a severe deterioration of relations between Washington and Turtle Bay. Trump has consistently opposed Obama’s turning to the U.N. to create facts on the ground for U.S. policymakers or to avoid Congress — from climate change to the Iran deal to control of the Internet. If the Security Council becomes a forum for exonerating Iran and slamming Israel, President Trump could even embrace the idea, already popular among congressional Republicans, of cutting U.N. funding. Or a Trump administration could weaken the U.N. from the inside by actions such as vetoing a wide variety of marginal resolutions that the United States would otherwise tolerate in the spirit of multilateralism. He could veto the reauthorization of U.N. peacekeeping missions, which bring with them plague and rape but are still in many ways the pride of the U.N. ||||| CLOSE The United Nations Security Council voted on a resolution demanding an end to Israeli settlements. The United States abstained from the vote. USA TODAY NETWORK The United Nations Security Council votes to pass a resolution condemning Israeli settlement construction at United Nations headquarters in New York on Dec. 23, 2016. (Photo: Justin Lane, epa) In an unprecedented diplomatic rebuke of Israel, the United States abstained Friday on a United Nations Security Council resolution demanding an end to Israeli settlements, allowing the highly charged measure to pass. The resolution was approved 14-0 with the one abstention. The vote was greeted with loud applause in the packed Security Council chamber. The measure demands Israel "immediately and completely cease all settlement activities in the occupied Palestinian territory, including East Jerusalem." It declares the establishment of settlements by Israel has "no legal validity and constitutes a flagrant violation under international law." In abstaining, the U.S. brushed aside calls for a veto by president-elect Donald Trump who, in an unprecedented move, managed to delay the vote a day by weighing in with Egypt, the initial sponsor of the resolution. In a tweet after the vote, Trump offered his reaction to the outcome: "As to the U.N., things will be different after Jan. 20th." As to the U.N., things will be different after Jan. 20th. — Donald J. Trump (@realDonaldTrump) December 23, 2016 U.S. Ambassador to the U.N. Samantha Power, in remarks to the council after the vote, said the U.S. position on the settlements has remained unchanged for five decades, and quoted a 1982 statement by then-President Ronald Reagan, which declared Washington “will not support the use of any additional land for the purpose of settlements.” "The U.S. has been sending the message that the settlements must stop, privately and publicly, for five decades," Power said. Settlement activity, she added, “harms the viability of a negotiated two-state outcome and erodes prospects for peace and stability in the region.” At the same time, she said, "Our vote does not in any way diminish our steadfast and unparalleled commitment to the security of Israel." Israel, she noted, "faces very serious threats in a very tough neighborhood." In a statement issued by his office, Israeli Prime Minister Benjamin Netanyahu said, "Israel rejects this shameful anti-Israel resolution at the U.N. and will not abide by its terms." "At a time when the Security Council does nothing to stop the slaughter of half a million people in Syria, it disgracefully gangs up on the one true democracy in the Middle East, Israel, and calls the Western Wall 'occupied territory.'" Netanyahu, whose relations with President Obama have been decidedly strained over the past eight years, said the U.S. administration "not only failed to protect Israel against this gang-up at the U.N., it colluded with it behind the scenes." "Israel looks forward to working with President-elect Trump and with all our friends in Congress, Republicans and Democrats alike, to negate the harmful effects of this absurd resolution," the statement said. The American Jewish Congress also expressed dismay with the move. "In the strongest terms possible, the American Jewish Congress is deeply disappointed with the Obama administration for shamefully abstaining on today's anti-Israel UN Security Council resolution," the group said in a statement. "By the U.S. abstaining, President Obama abandoned long standing American foreign policy of vetoing one-sided resolutions against Israel at the United Nations, and in doing so, he steps away from his presidency, turning his back on the unbreakable bond with our great ally Israel." At the U.N., Israeli ambassador Danny Danon criticized the U.S. abstention, saying he has "no doubt" the Trump administration will usher in a new era. In remarks to the council, he said Jews have conquered many obstacles in the past, and "we will overcome this evil decree, too." Pro-Israel lobby AIPAC said it was "deeply disturbed" the Obama Administration declined to veto what it called a "destructive, one-sided, anti-Israel resolution." "By adopting this resolution, the United Nations has once again served as an open forum to isolate and delegitimize Israel — America’s lone stable, democratic ally in the Middle East," AIPAC said in a statement. Read an equally bristling statement from the Central Conference of American Rabbis, the rabbinic arm of the United States reform movement, "The CCAR has frequently criticized the current Israeli settlement policy as an obstacle to peace. At the same time, the United Nations is not the arena in which to address these complex issues. Peace negotiations belong between the two parties involved. Further, the UN's obsessive and relentless criticism of Israel, while ignoring the unspeakable repression committed by illegitimate regimes and terrorist organizations worldwide, falsely and maliciously labels Israel uniquely as a pariah state." Palestinian authority ambassador to the U.N. Riyad Mansour thanked the council for the vote and said he believes it could contribute to prospects for peace talks. The resolution, he said, "may rightly be seen as a last attempt to preserve the two-state solution and revive the path for peace, to keep the hope alive." Although Egypt withdrew the measure Thursday, co-sponsors New Zealand, Malaysia, Venezuela and Senegal requested the vote take place Friday. To pass, it needed nine "aye" votes and no veto from a permanent council member — the United States, France, Russia, Britain or China. Earth-moving equipment stands in the disputed Israeli 'settlement' of Ramat Shlomo, Dec. 23 2016, after reports emerged that an additional 300 housing units are planned for this neighborhood just north of Jerusalem built on pre-1967 Arab lands. (Photo: Jim Hollander, EPA) In the past, the U.S. has vetoed a similar resolution, which Israel strongly opposes. White House officials said the administration's decision not to veto is consistent with its long-standing opposition to Israeli settlements, calling them an incitement to violence and an impediment to peace. The United Nations resolution "makes clear that both Israel and the Palestinians have to take steps to preserve the two-state solution," said Ben Rhodes, deputy national security adviser for strategic communications. Rhodes said the U.S. had nothing to do with the U.N. resolution, and that the Obama administration has been warning Israel for years that settlements were increasing its international "isolation." As for Trump's tweet, Rhodes said Obama remains in charge until Jan. 20. "There is one president at a time," he said. While the resolution does not call for sanctions on Israel, it amounts to a high-profile rebuke of the Israeli government and could hamper Israel's negotiating position in future peace talks. Palestinians argue that the expansion of settlements on the disputed land makes a peace deal even less likely. Under international law, Israeli settlements — built on Palestinian land occupied by Israel — are considered to be illegal. Some 600,000 Israelis live in east Jerusalem and on the West Bank, which the Palestinians seek as part of a future independent state. Israel captured both areas in the 1967 Mideast war. Israel argues the final status of the territories should be determined in any future talks on Palestinian statehood. Trump, who does not take office until Jan. 20, had issued a statement Thursday calling for a U.S. veto only hours before the initially scheduled vote. Trump spokesman Sean Spicer said the Republican president-elect spoke with Israeli Prime Minister Benjamin Netanyahu and Egyptian President Abdel Fattah el-Sisi about the proposed Security Council action Thursday. On Friday, Sisi's spokesman said the two leaders agreed to allow Trump's incoming administration a chance to take up the issue. "During the call, they discussed regional affairs and developments in the Middle East, and in that context the draft resolution in front of the Security Council on Israeli settlement," said spokesman Alaa Yousef. "The presidents agreed on the importance of affording the new U.S. administration the full chance to deal with all dimensions of the Palestinian case with a view of achieving a full and final settlement. A senior Palestinian official, speaking anonymously according to protocol, said Egypt didn’t consult with the Palestinians about delaying the vote and it was a “complete shock” for them, AP reports. Egypt represents Arab states on the security council. Egypt is the first Arab country to make peace with Israel, with whom it shares close security ties in a joint struggle against Islamic militants. Contributing: David Jackson Read or Share this story: http://usat.ly/2iokbVN ||||| U.S. President-elect Donald Trump tweeted Friday shortly after the UN Security Council voted in favor of an anti-settlement resolution allowed by an unprecedented U.S. abstention, saying, "As to the UN, things will be different after Jan. 20th." >> Get all updates on Israel, Palestinians and the U.S.: Download our App, sign up to Breaking News Alerts, and Subscribe The White House, in turn, blamed the passage of the resolution on Prime Minister Benjamin Netanyahu's settlement policies. "If we didn’t see acceleration in settlement activity and wouldn’t hear that kind of rhetoric from the Israeli government then maybe the U.S. would have taken take a different view," Deputy National Security Adviser Ben Rhodes said. Kerry also commented on the resolution Friday, saying that it rightly condemns "incitement and settlement activity." Kerry also called on both sides to advance a two-state solution. Read More: The full text of the UNSC resolution | Netanyahu: Obama 'colluded' against Israel | U.S.: Netanyahu responsible for the UNSC resolution passing | Minister: U.S. abandoned Israel | U.S. Ambassador to the UN Power's full Security Council speech. Trump's comment against the resolution and U.S. abstention seemed to lead the sentiments among American leaders, but not all in the U.S. found the resolution unfavorable. Left-wing American Jewish group J Street responded positively to the passing of the resolution, saying in a statement that it “reaffirms the need for a two-state solution and calls for a halt to actions by both sides that serve to undermine the prospects for peace.” Another American Jewish group, AIPAC, was on Trump's side of the issue, saying in a statement that it is "deeply disturbed by the failure of the Obama Administration to exercise its veto to prevent a destructive, one-sided, anti-Israel resolution from being enacted by the United Nations Security Council. "AIPAC expresses its appreciation to President-elect Trump and the many Democratic and Republican Members of Congress who urged a veto of this resolution," the statement said. "Despite all the good," Malcolm Hoenlein, the head of the Conference of Presidents of Major American Jewish Organizations, added, "this will become the legacy of President [Barack] Obama, and the U.S.-Israeli relations." Morton Klein, president of the Zionist Organization of America, told Haaretz that he was shocked and devastated after the vote. He suggested that once Trump becomes president, he may reconsider U.S. funding to the UN in the wake of the resolution. "I spoke to many of Trump's people, and he is considering what he is going to do to punish some of these countries economically, and he is also considering U.S. funding to the UN," he said. "I know he is considering it, but he has not said it publicly." Prominent American lawmakers also weighed in, with veteran Arizona Senator John McCain saying that the U.S. abstention in the UN vote on Israeli settlements makes the U.S. "complicit in this outrageous attack" against Israel. Fellow Senator Lindsey Graham also reacted negatively to the vote, saying that U.S. foreign policy under Obama "has gone from naive and foolish to flat-out reckless." The senior Republican senator, in a note on Twitter after the vote, said: "With friends like these, #Israel doesn't need any enemies." "Regardless of the terrorist attacks they suffer or the number of rockets fired their way, in the United Nations Israel is always the bad guy," said Graham, who has threatened to work to "suspend or significantly reduce" U.S. support for the United Nations over the resolution. U.S. House of Representatives Speaker Paul Ryan said in a statement the U.S. abstention was "absolutely shameful" and a "blow to peace." Senator Dianne Feinstein, meanwhile, said that “President Obama’s refusal to veto today's UN Security Council resolution condemning Israeli settlements sends a strong message that the United States still supports a two-state solution." "Ending settlement activity in the West Bank and East Jerusalem is an absolute necessity if we’re ever to achieve a lasting peace between Israel and the Palestinians," she said. Many Israeli leaders also responded to the vote negatively, with Likud minister Yuval Steinitz saying that the U.S. had "abandoned" Israel.

– The UN Security Council on Friday passed a resolution calling for an end to illegal Israeli settlements on the West Bank and in East Jerusalem, the BBC reports. The resolution passed the Security Council 14-0 with the US abstaining from the vote. Israeli settlements are seen as a major sticking point in relations with Palestine, but the US has blocked similar resolutions in the past. Here's what you need to know: CBS News calls it a "stunning culmination of years of icy relations" between Obama and Netanyahu that puts the president and the president-elect in direct opposition on a major foreign policy issue. Speaking of, Donald Trump issued a statement Thursday calling for the US to veto the resolution, resulting in Egypt withdrawing it, according to USA Today. But the resolution was reintroduced by New Zealand, Malaysia, Senegal, and Venezuela on Friday. "As to the UN, things will be different after Jan. 20," Trump tweeted following Friday's vote. The vote was, predictably, condemned by Israeli officials. "The United States abandoned Israel, its only ally in the Middle East," Haaretz quotes Israeli minister Yuval Steinitz as saying. In an opinion piece for the Washington Post, Eugene Kontorovich calls the vote a "folly" that will make it harder to resolve the "Palestinian issue" and may end up weakening the UN. The Northwestern law professor says the US' abstentian was the result of Obama wanting to "punish" Netanyahu because he doesn't like him while trying to "box in" Trump's foreign policy.

although endemic malaria is not seen in the united states of america ( usa ) , majority of infections are caused by travel to or from endemic places of malaria transmission . the world tourism organization estimates that there were 1 billion international travelers in 2010 , with notable increase in travel to africa and south asia . with the increase of travel and increase of immigrants , number of cases of malaria in usa has also been increasing . the prevention messages and health communication strategies have become even more important for protecting the traveling community from communicable diseases like malaria . centers for disease control and prevention ( cdc ) , usa in 2010 reported a total of 1,688 cases of imported malaria in usa which was a 14% increase when compared to 2009 . the aim of our study is to determine epidemiological characteristics and disease course of imported malaria in our hospital over the last 15 years . a retrospective chart review of 15 years ( 1998 - 2012 ) was performed to determine the number of malaria cases in adults , i.e. , individuals greater than 18 years of age at howard university hospital , a semi - urban hospital of district of columbia , usa . the cases were identified based on discharge diagnosis of malaria and those that had definite diagnosis of malaria were chosen . the cases were defined as definite if the results of a blood smear with wright - giemsa stain were positive for malarial parasites . the degree of parasitemia quantitatively accessed at the time of diagnosis could only be retrieved for patients diagnosed and treated after 2008 . the records of 37 patients with malaria during the study period were reviewed for demographic data , including the age , sex , place of origin , travel history , initial diagnosis , and prophylaxis , along with prior history of malaria and month and year of admission . laboratory data were also reviewed and included complete blood cell counts , blood chemistries , and blood smears . incubation period was defined as interval between dates of arrival at usa to the time of onset of symptoms . the initial diagnosis ( usually recorded as the admitting diagnosis on the discharge summary ) was recorded . the duration of illness from time of onset of symptoms to presentation in the hospital and their length of stay in hospital were recorded . the antimalarial treatment and response of the patient to the therapy was noted as well . travelers were defined as persons from usa travelled to endemic area of malaria and returned back . immigrants with recent travel were defined as persons from endemic areas of malaria living in usa and travelled to endemic areas . the diagnosis was confirmed by giemsa stained thick and thin films of patient s peripheral blood . african american accounted for the majority with 26 ( 70% ) , followed by asian 1 ( 3% ) , and race was unknown in 10 patients ( 27% ) . the majority of cases , 8 ( 22% ) , were seen in september ( fig . 2 ) . eighteen ( 49% ) were travelers , and most common place of travel was nigeria 20 ( 54% ) ( fig . 3 ) . only 4 ( 11% ) patients received chemoprophylaxis and a known past history of malaria was documented in 10 ( 27% ) of the cases . the majority ( 31/37 ) of the patients presented with fever and chills ( 84% ) , followed by headache in 19 cases ( 51% ) and generalized body aches in 12 cases ( 32% ) . the majority ( 31/37 ; 84% ) of cases the degree of parasitemia was available in 18 patients diagnosed and treated after 2008 , which ranged from 0.001% to 0.3% . all the 3 patients with p. vivax were treated with chloroquine with proguanil . among the 31 patients with p. falciparum , 14 ( 45% ) were treated with quinine along with clindamycin / doxycycline , 13 ( 42% ) received treatment with mefloquine , and 4 ( 13% ) were given atovaquone - proguanil . the most common laboratory abnormality noted was thrombocytopenia in 27 ( 73% ) of patients , followed by abnormal liver function tests in 30% . the majority ( 84% ) of patients had uncomplicated malaria , and complicated malaria was seen only in 16% of patients based on who criteria as shown in table 1 . the mean length of hospital stay was 3.5 days with a mortality rate of 2.7% . malaria is a vector - borne , febrile illness caused by plasmodium species which is transmitted by the bite of female anopheline mosquito . p. vivax , p. falciparum , p. ovale , p. malariae , and p. knowlesi are the 5 species of plasmodia , which have been identified to cause human malaria . malaria due to p. falciparum is the most deadly , and it predominates in africa . p. vivax is less dangerous but is more widespread , and the other 3 species are found much less frequently . it is important to study malaria cases in usa as it is one of the preventable and treatable diseases , if current recommended interventions are properly implemented ; prompt initiation of treatment for malaria is important to avoid mortality associated with it . malaria can present similarly as any other febrile illness , and the most commonly presented symptom would be fever with chills which was seen in 84% of our patients . other symptoms of malaria include nausea , vomiting , malaise , weakness , headache , diarrhea , abdominal pain , and coma . the most common complication in our patients was thrombocytopenia compared to acute respiratory distress syndrome ( ards ) , renal insufficiency , and cerebral malaria in a study done on imported malaria in us travelers . the incubation period of malaria varies between 7 to 420 days based on the species . the incubation period for p. falciparum can vary from 9 to 14 days but also be as short as 7 days ; the period for p. vivax is 12 to 17 days , and that for p. malariae is as long as 18 to 40 days . hypnozoites which are the dormant form can remain in the hepatocytes with p. vivax and p. ovale infections and can cause recurrent infection months or years after the initial infection . our patients had a mean incubation period of 8 days as 94% of them had p. falciparum . we also found that 70% of imported malaria cases were travelers , and chemoprophylaxis was taken by only 4 ( 11% ) patients . one patient took mefloquine , 1 pyrimethamine , the other took doxycycline , and unknown in the last one . similarly from the cdc data of imported malaria in usa , only 5% of the patients reported taking chemoprophylaxis . this fact confirms the importance of using more sufficient preventive measures for travelers specially travelers visiting friends and relatives in endemic areas . another interesting aspect of our study was that among the 28% of cases who were immigrants , a previous history of malaria was given in 10 patients ( 27% ) , and all of them ( 100% ) had p. falciparum . so , it is important to make patients admitted for p. falciparum malaria aware of the importance of chemoprophylaxis on revisiting those endemic areas for malaria as 1 time infection does not provide any immunity towards recurrent malaria . in our study , 94% and 8% of the cases were diagnosed with p. falciparum and p. vivax , respectively . in contrast to these findings , the distribution of imported malaria species in aukland , new zealand was reported to be 52.9% p. falciparum and 47.1% p. vivax , where a major part of the investigated population was indian migrants , and in another study by stark et al . reported 70% of p. vivax as the main species of imported malaria cases from pakistan to germany . these findings are consistent with the fact that p. falciparum predominates in african countries , and p. vivax predominates in asian countries . similar results were seen with imported malaria cases in usa that 72% from africa were p. falciparum and 74% from asia were p. vivax . traditionally , preparation of thick and thin peripheral blood smear with giemsa stain and demonstration of malaria parasites in rbc is the gold standard of diagnosing malaria . as expertise is needed in diagnosing this infection from the smear especially in countries where the disease is not endemic , the diagnostic trial could result in false negative , and lack of resources can contribute to misdiagnosis in endemic countries . now a newer method , like rapid diagnostic test ( rdt ) , is available to diagnose malaria by detecting circulating malarial antigen ; however , it can not aid in quantification or identification of plasmodium species . pcr is also available to diagnose malaria which is especially used in patients with a high suspicion for malaria with negative blood smears . we also noted that the majority of cases were from west africa with the peak month of incidence during september ( fig . 2 ) , although cdc surveillance showed a peak incidence in july and january for patients who traveled to africa due to the popular traveling time during holiday season in summer and early winter . however , this difference could be partially explained by travelers ( including immigrants with recent travel ) contributing to 70% of our cases , who usually return back at the end of summer vacation with reopening of schools . as per cdc data , it was found that the peak incidence of p. falciparum was seen in late august to early september as in our study where 94% of patients had p. falciparum . similar to these findings , the end of summer was the peak time for malaria case reports in germany among individuals returning or migrating from pakistan . although this is a study involving a small number of patients , similar studies from a single institute were reported by froude et al . in which 51 imported malaria cases during 1986 - 1991 from their institute at bronx , new york , usa were included , and moore et al . reported 59 imported malaria cases from their institute at houston , texas , usa during 1990 - 1993 . in our study , with prompt diagnosis and initiation of treatment , a good prognosis was seen with a mean length of hospital stay of 3.5 days . only 1 person ( 2.7% ) died of complicated malaria in whom diagnosis and treatment was delayed as travel history was not revealed by the patient at the time of admission . malaria is not a common infection in usa , so travel history is a key for early diagnosis , and most importantly any patient who has been in an endemic area in the year preceding the onset of malarial symptoms should be evaluated for the disease . due to an increase in international travels , imported malaria should be considered as one of the differentials in patients presenting with febrile illness from the endemic areas of malaria . as malaria is a treatable and preventable disease , there is increased need for creating awareness amongst travelers regarding chemoprophylaxis for effective prevention of this disease .

as endemic malaria is not commonly seen in the united states , most of the cases diagnosed and reported are associated with travel to and from the endemic places of malaria . as the number of imported cases of malaria has been increasing since 1973 , it is important to look into these cases to study the morbidity and mortality associated with this disease in the united states . in this study , we would like to share our experience in diagnosing and treating these patients at our institution . we did a retrospective chart review of 37 cases with a documented history of imported malaria from 1998 to 2012 . among them , 16 patients had complicated malaria during that study period , with a mean length of hospital stay of 3.5 days . most common place of travel was africa , and chemoprophylaxis was taken by only 11% of patients . travel history plays a critical role in suspecting the diagnosis and in initiating prompt treatment .

SECTION 1. SHORT TITLE. This Act may be cited as the ``Ruth Moore Act of 2013''. SEC. 2. STANDARD OF PROOF FOR SERVICE-CONNECTION OF MENTAL HEALTH CONDITIONS RELATED TO MILITARY SEXUAL TRAUMA. (a) Standard of Proof.--Section 1154 of title 38, United States Code, is amended by adding at the end the following new subsection: ``(c)(1) In the case of any veteran who claims that a covered mental health condition was incurred in or aggravated by military sexual trauma during active military, naval, or air service, the Secretary shall accept as sufficient proof of service-connection a diagnosis of such mental health condition by a mental health professional together with satisfactory lay or other evidence of such trauma and an opinion by the mental health professional that such covered mental health condition is related to such military sexual trauma, if consistent with the circumstances, conditions, or hardships of such service, notwithstanding the fact that there is no official record of such incurrence or aggravation in such service, and, to that end, shall resolve every reasonable doubt in favor of the veteran. Service-connection of such covered mental health condition may be rebutted by clear and convincing evidence to the contrary. The reasons for granting or denying service-connection in each case shall be recorded in full. ``(2) For purposes of this subsection, in the absence of clear and convincing evidence to the contrary, and provided that the claimed military sexual trauma is consistent with the circumstances, conditions, or hardships of the veteran's service, the veteran's lay testimony alone may establish the occurrence of the claimed military sexual trauma. ``(3) In this subsection: ``(A) The term `covered mental health condition' means post-traumatic stress disorder, anxiety, depression, or other mental health diagnosis described in the current version of the Diagnostic and Statistical Manual of Mental Disorders published by the American Psychiatric Association that the Secretary determines to be related to military sexual trauma. ``(B) The term `military sexual trauma' means, with respect to a veteran, psychological trauma, which in the judgment of a mental health professional, resulted from a physical assault of a sexual nature, battery of a sexual nature, or sexual harassment which occurred during active military, naval, or air service.''. (b) Annual Reports.-- (1) In general.--Subchapter VI of chapter 11 of title 38, United States Code, is amended by adding at the end the following new section: ``Sec. 1164. Reports on claims for disabilities incurred or aggravated by military sexual trauma ``(a) Reports.--Not later than December 1, 2014, and each year thereafter through 2018, the Secretary shall submit to Congress a report on covered claims submitted during the previous fiscal year. ``(b) Elements.--Each report under subsection (a) shall include the following: ``(1) The number of covered claims submitted to or considered by the Secretary during the fiscal year covered by the report. ``(2) Of the covered claims listed under paragraph (1), the number and percentage of such claims-- ``(A) submitted by each sex; ``(B) that were approved, including the number and percentage of such approved claims submitted by each sex; and ``(C) that were denied, including the number and percentage of such denied claims submitted by each sex. ``(3) Of the covered claims listed under paragraph (1) that were approved, the number and percentage, listed by each sex, of claims assigned to each rating percentage. ``(4) Of the covered claims listed under paragraph (1) that were denied-- ``(A) the three most common reasons given by the Secretary under section 5104(b)(1) of this title for such denials; and ``(B) the number of denials that were based on the failure of a veteran to report for a medical examination. ``(5) The number of covered claims that, as of the end of the fiscal year covered by the report, are pending and, separately, the number of such claims on appeal. ``(6) For the fiscal year covered by the report, the average number of days that covered claims take to complete beginning on the date on which the claim is submitted. ``(7) A description of the training that the Secretary provides to employees of the Veterans Benefits Administration specifically with respect to covered claims, including the frequency, length, and content of such training. ``(c) Definitions.--In this section: ``(1) The term `covered claims' means claims for disability compensation submitted to the Secretary based on a covered mental health condition alleged to have been incurred or aggravated by military sexual trauma. ``(2) The term `covered mental health condition' has the meaning given that term in subparagraph (A) of section 1154(c)(3) of this title. ``(3) The term `military sexual trauma' has the meaning given that term in subparagraph (B) of such section.''. (2) Clerical amendment.--The table of sections at the beginning of such chapter is amended by adding at the end the following new item: ``1164. Annual reports on claims for disabilities incurred or aggravated by military sexual trauma.''. (c) Effective Date.--Subsection (c) of section 1154 of title 38, United States Code, as added by subsection (a), shall apply with respect to any claim for disability compensation under laws administered by the Secretary of Veterans Affairs for which no final decision has been made before the date of the enactment of this Act.

Ruth Moore Act of 2013 - Directs the Secretary of Veterans Affairs (VA), in any case in which a veteran claims that a covered mental health condition was incurred in or aggravated by military sexual trauma during active duty, to accept as sufficient proof of service-connection a diagnosis by a mental health professional together with satisfactory lay or other evidence of such trauma and an opinion by the mental health professional that such condition is related to such trauma, if consistent with the circumstances, conditions, or hardships of such service, notwithstanding the fact that there is no official record of such incurrence or aggravation in such service, and to resolve every reasonable doubt in favor of the veteran. Allows such service-connection to be rebutted by clear and convincing evidence to the contrary. Includes as a &quot;covered mental health condition&quot; post-traumatic stress disorder, anxiety, depression, or any other mental health diagnosis that the Secretary determines to be related to military sexual trauma. Requires the Secretary to report annually to Congress in each of 2014 through 2018 on covered claims submitted.

SECTION 1. SHORT TITLE. This Act may be cited as the ``Fair Access to Investment Research Act of 2015''. SEC. 2. SAFE HARBOR FOR INVESTMENT FUND RESEARCH. (a) Expansion of Safe Harbor.--Not later than the end of the 45-day period beginning on the date of enactment of this Act, the Securities and Exchange Commission shall propose, and not later than the end of the 120-day period beginning on such date, the Commission shall adopt, upon such terms, conditions, or requirements as the Commission may determine necessary or appropriate in the public interest, for the protection of investors, and for the promotion of capital formation, revisions to section 230.139 of title 17, Code of Federal Regulations, to provide that a covered investment fund research report-- (1) shall be deemed, for purposes of sections 2(a)(10) and 5(c) of the Securities Act of 1933, not to constitute an offer for sale or an offer to sell a security that is the subject of an offering pursuant to a registration statement that the issuer proposes to file, or has filed, or that is effective, even if the broker or dealer is participating or will participate in the registered offering of the covered investment fund's securities; and (2) shall be deemed to satisfy the conditions of subsection (a)(1) or (a)(2) of section 230.139 of title 17, Code of Federal Regulations, or any successor provisions, for purposes of the Commission's rules and regulations under the Federal securities laws and the rules of any self-regulatory organization. (b) Implementation of Safe Harbor.--In implementing the safe harbor pursuant to subsection (a), the Commission shall-- (1) not, in the case of a covered investment fund with a class of securities in substantially continuous distribution, condition the safe harbor on whether the broker's or dealer's publication or distribution of a covered investment fund research report constitutes such broker's or dealer's initiation or reinitiation of research coverage on such covered investment fund or its securities; (2) not-- (A) require the covered investment fund to have been registered as an investment company under the Investment Company Act of 1940 or subject to the reporting requirements of section 13 or 15(d) of the Securities Exchange Act of 1934 for any period exceeding twelve months; or (B) impose a minimum float provision exceeding that referenced in subsection (a)(1)(i)(A)(1)(i) of section 230.139 of title 17, Code of Federal Regulations; (3) provide that a self-regulatory organization may not maintain or enforce any rule that would-- (A) condition the ability of a member to publish or distribute a covered investment fund research report on whether the member is also participating in a registered offering or other distribution of any securities of such covered investment fund; (B) condition the ability of a member to participate in a registered offering or other distribution of securities of a covered investment fund on whether the member has published or distributed a covered investment fund research report about such covered investment fund or its securities; or (C) require the filing of a covered investment fund research report with such self-regulatory organization; and (4) provide that a covered investment fund research report shall not be subject to sections 24(b) or 34(b) of the Investment Company Act of 1940 or the rules and regulations thereunder. (c) Rules of Construction.--Nothing in this Act shall be construed as in any way limiting-- (1) the applicability of the antifraud provisions of the Federal securities laws; or (2) the authority of any self-regulatory organization to examine or supervise a member's practices in connection with such member's publication or distribution of a covered investment fund research report for compliance with otherwise applicable provisions of the Federal securities laws or self- regulatory organization rules. (d) Interim Effectiveness of Safe Harbor.--From and after the 120- day period beginning on the date of enactment of this Act, if the Commission has not met its obligations pursuant to subsection (a) to adopt revisions to section 230.139 of title 17, Code of Federal Regulations, and until such time as the Commission has done so, a covered investment fund research report published or distributed by a broker or dealer after such date shall be deemed to meet the requirements of section 230.139 of title 17, Code of Federal Regulations, and to satisfy the conditions of subsection (a)(1) or (a)(2) thereof for purposes of the Commission's rules and regulations under the Federal securities laws and the rules of any self-regulatory organization, as if revised and implemented in accordance with subsections (a) and (b). (e) Definitions.--For purposes of this Act: (1) Covered investment fund research report.--The term ``covered investment fund research report'' means a research report published or distributed by a broker or dealer about a covered investment fund or any of its securities. (2) Covered investment fund.--The term ``covered investment fund'' means-- (A) an investment company registered under, or that has filed an election to be treated as a business development company under, the Investment Company Act of 1940 and that has filed a registration statement under the Securities Act of 1933 for the public offering of a class of its securities, which registration statement has been declared effective by the Commission; and (B) a trust or other person-- (i) that has a class of securities listed for trading on a national securities exchange; (ii) the assets of which consist primarily of commodities, currencies, or derivative instruments that reference commodities or currencies, or interests in the foregoing; and (iii) that allows its securities to be purchased or redeemed, subject to conditions or limitations, for a ratable share of its assets. (3) Research report.--The term ``research report'' has the meaning given to that term under section 2(a)(3) of the Securities Act of 1933, except that such term shall not include an oral communication. (4) Self-regulatory organization.--The term ``self- regulatory organization'' has the meaning given to that term under section 3(a)(26) of the Securities Exchange Act of 1934.

. Fair Access to Investment Research Act of 2015 (Sec. 2) This bill directs the Securities and Exchange Commission (SEC) to revise a specified regulation to create a safe harbor for certain publications or distributions of research reports by brokers or dealers distributing securities. The revised regulation shall declare that, even if a broker or dealer participates in the registered offering of a covered investment fund's securities, the investment fund research report shall not be deemed to constitute an offer for sale nor an offer to sell a security that is the subject of the offering pursuant to a registration statement that the issuer proposes to file, or has filed, or that is effective. The covered investment fund research report shall indeed be deemed to satisfy the regulation's requirements as well as those of any self-regulatory organization. The SEC shall not impose specified conditions and requirements when implementing the safe harbor.

large efforts have been devoted to explore the origin of cosmic rays . most puzzling are the observed ultra - high energy cosmic ray events ( uhecrs ) above the gzk - cutoff @xcite : protons lose energy drastically due to pion photo - production processes on the cosmic microwave background ( cmb ) at energies higher than @xmath6 ev , and this limits the proton mean free path to some tens of megaparsecs ( see @xcite and @xcite for more discussion on the gzk cut - off ) . two distinctly different classes of models are commonly considered , the top - down and bottom - up scenarios . in the former ones , uhecrs are associated e.g. with the decay of some supermassive particles , whereas in the latter scenarios uhecrs are assumed to be accelerated by astrophysical objects ( e.g. @xcite , and for a latest review we refer the interested reader to @xcite ) . a growing number of bottom - up explanations have been proposed , including active galactic nuclei , gamma ray bursts and neutron stars . however , at present there seems to be no clear association of uhecr events with any of these objects although by tuning the model parameters one enables the highest energy events to be accounted for . identifying sources of the observed uhecr events remains uncertain and debated leaving room for speculation ( @xcite ) . as such we wish to consider in this paper the possibility that hypothetical quark novae ( hereafter , qne ; @xcite ) contribute to the cosmic ray flux , especially above @xmath3 ev . in the qn explosion the core of a neutron star ( ns ) shrinks into the equilibrated quark object / star ( qs ) . the overlaying crust material free - falls following the core contraction releasing enough energy to form an ultra - relativistic ejecta . the ultra - relativistic shock interaction with its surroundings environment ( namely the randomised relativistic wind of the progenitor ) leads to the first cosmic ray component in our model . the compact remnant acting as a magnetohydrodynamic propeller provides the second component , injecting ions to be boosted by the ultra - relativistic quark nova shock . most of the propelled wind of relativistic particles is injected into interstellar space with low energies ( from gev to tev ) , and these particles can be further on accelerated by galactic supernova shocks . thus the propeller can contribute to cosmic ray flux also below the knee as an injector . it appears that the qn model can largely contribute for the extragalactic cosmic rays above the ankle and contribute a few percent of the galactic cosmic rays around and below the knee . the main assumption in this paper is the conversion of a highly magnetised , rapidly spinning ns to a qs . this phase conversion ( or second explosion ) which remains to be confirmed leads to unique conditions where two uhecr components are feasible . it is this unique aspect of the model that makes this investigation worth pursuing . we note however that the approach presented here ( including the acceleration mechanisms as related to the dynamics of the explosion ) borrows heavily from what has already been presented in the literature for models of uhecrs in the context of isolated pulsars and binary coalescence ( e.g. , @xcite to cite only few ) . this paper is presented as follows : we start with a brief review of the concept of quark nova and its features ( 2 ) . in 3 we describe conditions under which the compact remnant is born in a propeller regime . in 4 we explain how cosmic rays are produced and isolate the two components ( with energies @xmath0 and @xmath1 ev ) . here we describe the qn compact remnant as an injector of relativistic particles to the galaxy . in 5 we predict uhecr events in future detectors and discuss multiple events and the isotropy of sources in our model . a discussion and a conclusion follow in 6 it has been suggested that the core of neutron stars may deconfine to a composition of up ( @xmath7 ) and down ( @xmath8 ) quarks during or shortly after some supernova explosions when the central density of the proto - neutron star is high enough to induce phase conversion ( see e.g. @xcite ) . it has also been speculated that when the density in the core increases further , a phase with strange quarks ( @xmath9 ) becomes energetically favoured over the pure _ ( u , d ) _ phase and soon the entire star is contaminated and converted into this _ ( u , d , s ) _ phase . this is one of the scenarios introduced to convert an entire ns to a qs ( e.g. , @xcite ) . in the qn picture the _ ( u , d , s ) _ core is assumed to shrink to a corresponding stable quark object before the contamination is spread over the entire star . by physically separating from the overlaying material ( hadronic envelope ) the core drives the collapse ( free - fall ) of the left - out matter leading to both gravitational energy and phase transition energy release as high as @xmath10 ergs ( @xcite ) . the qn - ejecta consist mainly of heavy nuclei ( the ns crust ) , protons , electrons and neutrons . the total amount of the ejecta has been estimated to be of the order of @xmath11 with corresponding lorentz factor @xmath12 , where @xmath13 is the percentage of the qn energy transfered to the qn shock front which we assume to 10% . the radius of the newly formed qs is given by @xmath14 where the ns core density , @xmath15 , and the qs density , @xmath16 , scale as @xmath17 @xcite _ hereafter parameters with no subscripts refer to the quark star_. the qs spins up during the phase transition due to contraction , with a rotational period @xmath18 . in the process , the magnetic field is amplified , @xmath19 . fall - back of material onto a newly formed quark star may take place ( similar to what has been suggested in the supernova case ; @xcite ) . in the early stages the accretion rate is given by @xmath20 where @xmath21 is the average density of fall - back matter ( @xmath22 g/@xmath23 , representing the crust material , and the matter below the neutron drip line densities ) . the hyper - eddington accretion rate given above is understood by noting that ( i ) the fall - back matter in the initial phase of the explosion is not accreted onto the surface ( but is propelled away before radiating ) , and ( ii ) the crust would not form in the early stages leaving the quark star bare ( not subject to the eddington limit since the bulk of the star is bound via strong interaction rather than gravity ; see e.g. @xcite , and @xcite for a recent discussion on the matter ) . for the remainder of this paper , we consider a qs ( ns ) mass of @xmath24 ( @xmath25 ) , a radius @xmath26 km ( @xmath27 km ) , a surface magnetic field of @xmath28 g ( @xmath29 g ) . since the fastest pulsar has a period of @xmath30 ms @xcite , we use @xmath31 ms as a representative value for the period @xmath32 of the new born quark star ( @xmath33 ms ) . clearly these are unique constraints ( millisecond , highly magnetised ns ) favouring a scenario where the qs forms immediately following a sn explosion , or that where the ns has been spun up by accretion from a companion . the newly born quark star is defined by its three critical radii : the keplerian `` co - rotation radius '' @xmath34 the magnetospheric radius at which the ram pressure of the in - falling matter balances the magnetic pressure @xmath35 ( see , e.g. @xcite ) , and the light cylinder radius @xmath36 given our fiducial values , the qs is born in the propeller regime @xcite , i.e. @xmath37 , where the infalling material may be accelerated in a wind that carries away angular momentum from the magnetosphere and hence from the qs itself ( 4.2 ) . note that the propeller regime is only possible if the quark star is born with a magnetic field exceeding the critical value @xmath38 g , which corresponds to a parent neutron star initial magnetic field @xmath39 g. here c " stands for critical " while the factor 4 ( derived from our fiducial values ) is the result of the amplification of the magnetic field following the quark - nova explosion . these critical values explain our assumption of a highly magnetised , rapidly spinning ns . the star loses rotational energy at a rate defined by the gravitational radiation losses ( @xmath40 ) , electromagnetic radiation losses ( @xmath41 ) and the propeller s torque ( @xmath42 ) . that is , @xmath43 with @xcite @xmath44 where @xmath45 is the moment of inertia and @xmath13 the equatorial eccentricity ; and with @xcite @xmath46 the spin - down due to the propeller is @xcite @xmath47 the expression above assumes that the material flung away by the propeller effect has been accelerated to an angular speed corresponding to that of the star . we note that gravitational losses would be important in the spin - down for very short periods @xmath48 ms ( not our case ) and propeller losses dominate over the electromagnetic dipole radiation losses given our accretion rates . the propeller regime lifetime can be obtained using eq . ( [ eq7 ] ) and eq . ( [ eq10 ] ) . we find , assuming a constant accretion rate , @xmath49 where @xmath50 and @xmath51 , initial and final periods , are in milliseconds . for a constant accretion rate , and taken the total amount of the qn ejecta , the lifetime of the propeller phase would not exceed a hundred seconds during which time the qs would have spun - down by no more than 30% thus remaining within milliseconds period . following this phase , the spin - down is governed by the magnetic dipole radiation losses of the qs . we assume that the pulsar wind is composed of electron - positron pairs and ions , as would be expected if pulsars operate as open - circuited systems with ions carrying the return current @xcite . some fraction of ions can be heavy like iron , originating from the surface of the pulsar . we also assume that the wind has been subject to a termination shock as to acquire a randomised direction of particle momenta @xcite . the number density of electron - positron pairs is @xmath52 ( @xmath53 is the goldreich - julian density ; @xcite ) where @xmath54 is the electron charge . we adopt @xmath55 as the relativistic factor of most of the wind particles ( see e.g. @xcite ) , and the ratio of ions to electron - positron pairs to be @xmath56 ; ions carrying most of the energy of the wind . for future purposes , we write the ion density as @xmath57 where the index @xmath58 describes the radial dependency . the qn ejecta will interact with the parent ns wind . the randomised wind particles will be boosted with one shock crossing by a factor of @xmath59 before they leave the region . the maximum number of particles that can be accelerated is limited by the qn fireball energy and can be written as ( here the energy of the pairs will be negligible , since energetically they are at much lower gamma factors due to synchrotron losses ) @xmath60 where @xmath61 is the proton mass , @xmath62 can vary from @xmath63 to @xmath64 ( iron ) and @xmath13 is the fraction of qn energy transferred via the qn shock to the pulsar wind particles . if all ions are protons and approximately accelerated to the energies of the ankle ( around @xmath65 ev ) , then up to @xmath66 particles would gain that energy . heavier ions will correspondingly reach higher energies with the same total relativistic factor @xmath67 , e.g. iron will easily gain energies over @xmath68 ev . therefore in this model at higher energies there should be a natural increase in heavier ions . since the above follows closely calculations already presented in @xcite , the corresponding spectrum also in our case can be shown to be @xmath69 or even flatter given its dependency on @xmath70 . we would like to emphasize that further studies of our model are needed in order to make better predictions of the spectrum . such an injection spectrum might agree with agasa measurements but let us recall that in the high energy region we discuss here , currently there seems to be a disagreement between the agasa ground array ( takeda et al . 1999 ) and the hires fluorescence detector ( abu - zayyad et al . 2002 ) which seems consistent with the gzk - cutoff . clearly there is a need for much larger experiments such as auger , euso , and owl , that can increase the number of detected events by one or two orders of magnitude before the injection spectrum is known conclusively . as we have said , for now , our model lacks the details to predict the exact spectrum . the number of particles per unit volume from qne in all the galaxies is @xmath71 , where @xmath72 is the residence time of a particle at the ankle initially injected at higher energy @xcite . the qn rate per galaxy is given by @xmath73 while @xmath74 is the galaxy density . with @xmath75 yr@xmath76 and @xmath77 mpc@xmath78 , this implies @xmath79 as compared to the observed value @xmath80 @xmath81 s@xmath76 ster@xmath76 ( 1 event per square kilometer per year ; @xcite ) , assuming @xmath82 . for particles at energies higher than @xmath65 ev we used an average @xmath83 gyr ( biermann&strittmatter 1987 ; berezinsky & grigoreva 1988 ; bertone et al . 2002 ; see also figure 5 in sigl 2004b ) . the qn flux calculated above is short of the observed one unless the qn is very efficient in transferring energy via the qn shock into relativistic particles . however the presence of large scale magnetic field complicates the interpretation of uhecrs data and could lead to an overestimate of the observed flux . more specifically , the energy spectrum of particles emitted from a ( nearby ) source depends very strongly on the relative position of the observed source and the observer to the direction of the large scale field . in some cases the flux can be enhanced by a factor of @xmath84 for energies below @xmath5 ev ( see stanev et al . 2003 and references therein ) . the observed flux and spectrum might not reflect the ones at the source making uncertain a direct comparison with the numbers derived above . the ejecta remain in expansion phase until the shock starts to decelerate . the transition between these two phases occurs at a radius @xmath85 at which the energy in the swept - up material becomes of the order of the energy released in the qn , i.e when a large fraction of the fireball energy has been used to reaccelerate the wind particles ( @xcite ) . using eq.([ni ] ) , @xmath86 which gives @xmath87 cm for @xmath88 . if the ion density decreases as @xmath89 ( @xmath90 ) , the fireball will be in the expansion phase much longer and the distance should be defined by using interstellar matter density together with the wind ( we estimate @xmath91 cm for @xmath92 ) . these numbers will define the timescale of the highest energy cosmic ray component acceleration . the case with @xmath93 would more closely follow the magnetic field value and therefore the charge density of the pairs . we use it as an example . the corresponding time is @xmath94 s. if all wind particles are iron , then the timescale would be shorter , @xmath95 s. one should notice however that the ion density profile in the pulsar wind bubble is not known and therefore the timescale of the expansion phase could be much larger ( with @xmath96 up to weeks ) . the second cosmic ray component occurs when rapidly rotating millisecond pulsars with large magnetic fields , @xmath97 g , undergo a qn explosion . in this case the born qs is in the propeller regime ( see 3 ) . the material flung away by the propeller expands as a magneto - hydrodynamic wind to reach the speed of light ( with lorentz factors up to @xmath98 at the light cylinder for @xmath99 g ; see @xcite for detailed calculations ) . the mhd nature of the propeller ensures that acceleration occurs at large distances from the star where synchrotron losses are likely to be minimum . as demonstrated in @xcite the magnetic field above the alfvn surface is predominantly toroidal . such a geometry will allow the particles to escape freely along the poloidal direction in the acceleration zone without being deflected by the magnetic field lines . particles with @xmath100 can reach eventually the qn shock , as to reach lorentz factors as high as @xmath101 . it is roughly @xmath102 ev for protons and @xmath3 ev for iron in one shock crossing . since an efficient propeller needs strong magnetic field and a short period , this component is created in young pulsars soon after the supernova explosion or in binaries where the neutron star spins up ( which also provides extra mass to trigger the qn ) . if the propeller works with the extreme accretion rate of @xmath103 g s@xmath76 , then the rate of particle number is @xmath104 s@xmath76 . that is , after one crossing , where a particle is boosted by a factor @xmath105 , the energy in time unit used to accelerate the propeller wind is @xmath106 ; only the particles with @xmath107 will be accelerated by the qn shock . this indicates that particle acceleration consumes the energy of the shock wave in @xmath108 ms , and the shock dies out . we expect the propeller to function efficiently in its early stages with most particles acquiring @xmath109 . in reality this timescale is longer because the propeller wind particles can not propagate straightforwardly to the shock ( due to magnetic field and turbulence ) , their energies must have spread out and the most energetic particles reach the shock first ; nevertheless , it is short compared to the timescale of the expansion phase . it also means that a tiny amount of the bulk of the propeller wind will be accelerated to energies of the order of @xmath110 ev and at most up to @xmath3 ev for those few particles that managed to get one more kick in the process . here again , given the many similarities to the calculations and approach presented in @xcite , we expect the boosted propeller wind to acquire a power law spectrum , @xmath111 with @xmath112 . using the milky way dimensions with a radius of 15 kpc and a scale height of @xmath113 1 kpc , we obtain the number density of galactic cosmic rays for one qn to be of the order of @xmath114 . we assume a leaky box model @xcite for the galactic cosmic rays diffusing out of the galaxy where we adopt the leakage timescale expressed as @xmath115 ( see e.g. webber 1998 ; biermann et al . , 2001 and biermann & sigl , 2001 ) . the estimated time - averaged flux in our model is , @xmath116 which is similar to the observed value of @xmath117 @xmath81 s@xmath76 ster@xmath76 ( @xcite ) as long as the hyper - eddington accretion rates can be accepted and if the accelerated particles are mainly protons . notice that below the knee @xmath118 is too low to account for the observed cosmic ray flux ; the shock is not energetic enough to accelerate more particles as to extend the spectrum to lower energies . therefore , the steeper spectrum above the knee provided by the qn shock can not dominate at energies below the knee . more important , the flux in eq.(14 ) is averaged over time , @xmath119 . above the knee the cosmic ray diffusion time is shorter than the qn occurrence , @xmath120 . for example , at the knee @xmath121 years for protons and it is @xmath122 years at the ankle , while the qn occurrence time is @xmath123 years . therefore the propelled wind of the qn model can account for the galactic cosmic ray flux locally , i.e. in the vicinity and shortly after the qn event . over the whole galaxy and in timescales longer than millions of years , qne can contribute on average a few percent of the galactic cosmic rays around the knee . closer to the ankle the contribution is negligible due to the very short diffusion time @xmath124 . more accurate estimates of the leakage times at high energies and qne occurrence would be needed to make the above conclusions firm . in particular , the qn rate carries substantial uncertainties ; among them the difficulty of determining the critical density for the transition to quark matter , the burden of not knowing which equation of state better describes the parent ns , and the lack of a complete theory that can describe the qcd phase diagram that would describe the path followed by the ns during its transition to a quark star . we note however that recent studies show that qn rates can be as high @xmath125 ( yasutake , hashimoto , & eriguchi 2004 ) . which is above our fiducial value of @xmath126 . finally , since the propelled wind consists of the crust material of the parent ns , we expect this cosmic ray component to be rich in heavier ions , up to iron . their rigidity ( @xmath127 ) means that these heavy nuclei would leak out of the galaxy at a lower rate than protons . it implies an increase of the heavy nuclei to hydrogen ratio in the chemical composition over time for those cosmic rays originating in qne . in our model the propeller injects relativistic particles . as discussed above , some of this propelled material can be re - accelerated by the qn shock . the remaining bulk will populate interstellar space . these particles with lorentz factors @xmath128 ( or energies 1 - 1000 gev for protons ) could later be reaccelerated by galactic supernova shocks . for the number of injected particles a simple estimate gives @xmath129 that are accelerated to gev energies by the propeller . here @xmath130 is the maximum rotational energy of the qs . using eq . [ mwrays ] this implies @xmath131 , which is a few percent of the observed value ( see e.g. @xcite ) . in this case the particle density in the galaxy can reach @xmath132 from a single qn using up the qs rotational energy . the spectrum of the population of these injected particles will be shaped by later encounters and acceleration by galactic supernova shocks . we note here as well that at most a few percent of the cosmic rays below the knee can be of the qn origin . the qn model predicts three cosmic ray components , two galactic ones and an extragalactic one . this should in principle lead into transitions or steps in the cosmic ray flux . the galactic components will be subject to many sn shocks that will smoothen the discontinuity around the knee . note however that these signatures will be dwarfed by the much higher contribution from other galactic cosmic ray sources . having shown that qne are candidate sources of uhecrs above the ankle , we next discuss how observational features can be explained within the qn model . with a rate of @xmath133 per galaxy per year and a galaxy density @xmath134 mpc@xmath78 one should expect about @xmath135 qne a year within a @xmath136 mpc sphere . this 100 mpc region contains galactic and intergalactic magnetic field regions to which gzk - energy cosmic rays are subject to . this may lead to arrival time delay and therefore clustering of events around the source . the arrival timescales can spread from years to millions of years depending on the strength and the configuration of the magnetic field as well as the distance to the qn . here we refer the interested reader to sigl ( 2004a ) for a recent discussion on the effect of the magnetic field on the ultra - high energy cosmic rays . given these numbers , there may be a tiny energy window with the particles clustering within a few degrees towards the source ( e.g , kronberg 1994a and 1994b ) . this wishful possibility lead us to consider such events in the future detectors what we refer to as observational particle astronomy . naturally , such observations will be better guided if the qn can be detected by other means as well ( e.g. x - rays , gamma - rays ) . the energy lost by the uhecrs as they propagate and interact with the cosmic microwave background is transformed by cascading into secondary gev - tev photons ( protheroe&stanev 1996 ) . this tev - gamma - uhecr trace could in principle be detected in the future ( catenese&weekes 1999 ) and be used to test our model ( see discussion in akerlof et al . 2003 and references therein ) . however photons and uhecrs may have very different arrival times that are not easily quantified . this again calls for better understanding of magnetic field effects before such connections between the tev photons and the related uhecrs can be made . also , since protons can be accelerated up to @xmath137 ev in our model , significant neutrino fluxes ( with energies above @xmath3 ev ) can be generated ( e.g. , waxman&bahcall 1999 ; engel et al . this is below the currently advertised threshold of @xmath138 ev for euso and owl and most of the potential events will go undetected ( halzen&hooper 2002 ) . nevertheless future neutrino detectors should be able to signal any neutrino - uhecr trace with the arrival direction of ultra - high - energy neutrinos as a good indication of the qn location . the above mentioned traces are the subject of another study of qne as sources of uhecrs . assuming that the cosmic rays above the ankle are accelerated in qne , we obtain roughly @xmath139 particles above @xmath5 ev per qn . the integrated flux f per unit area from one qn is @xmath140 where the @xmath141 is the qn distance . this is the total flux integrated over time including the spread in arrival time induced by magnetic fields , which can vary from years to millions of years ( sigl 2004a ) . in a detector like auger this implies ( integrated over the year and aperture and assuming that the qn is within the sky coverage ) few hundred events per one qn at a distance of 100 mpc . in a detector like euso and owl one can expect one to two orders of magnitude more events per qn . if the time delay and thus the spread in arrival time is e.g. 1000 years , one could expect doublets and triplets around a given qn within 10 year time in auger , and equivalently dozens of clustered events with euso and owl . for completeness , if the average time delay of cosmic rays above @xmath5 ev is around 1000 years , in our model it would mean that uhecrs from roughly 100 qne can presently be detected within 100 mpc . unlike the arrival directions of uhecrs , the galaxy distribution is not isotropic within 100 mpc distance . this may mean that uhecr accelerators are not all within galaxies . it is natural to attribute uhecr sources to galaxies and the almost perfect isotropy , sofar observed both below and above the ankle ( e.g. torres&anchordoqui 2004 ) , to magnetic fields . despite the uncertainties on the magnetic field strength it has indeed been shown that if our local supercluster contains a large scale magnetic field it can provide sufficient bending to the cosmic ray trajectories ( sigl , lemoine & biermann 1999 ; farrar&piran 2000 ) . heavy ions like iron , if present in the pulsar wind , will have unique consequences . iron has a higher cutoff energy ( @xcite ) than lighter nuclei thus allowing a longer path of propagation in a tiny energy window allowing for more distance sources to contribute to the flux . furthermore , being bent in galactic and intergalactic fields , heavy nuclei would acquire a more isotropic distribution of arrival directions than protons . finally , heavy nuclei will naturally acquire higher energies than protons and contribute to the extreme end of the uhecr flux in our model . of interest to the qn model , old population pulsars with large peculiar velocities to @xmath142 km s@xmath76 and their mean three - dimensional speed is @xmath143 km s@xmath76 ( lyne & lorimer , 1994 ) . ] could cover tens of mpc distances from their origins in a hubble time . some of these run - away pulsars may undergo a qn explosion as a result of an increase of their core densities following spin down or accretion from the surrounding space . this would lean towards a more isotropic distribution - the extent of isotropy in the runaway pulsar population remains to be determined - of the arrival directions of the uhecrs ( the qn - shock boosted pulsar wind ) . this favours weak magnetic field ( @xmath144 g ) millisecond pulsars in our model , with the assumption that these old isolated pulsars still sustain their wind bubbles . we note that these candidates are probably not born in the propeller regime following the qn explosion , given their weak magnetic field and long periods ( see 3 ) . for a given distant extragalactic qn source the more energetic particles should arrive first since the associated time delay induced by the intergalactic magnetic fields is short . therefore it would appear as if there is a monoenergetic flux of particles from the source at one given time . later , the lower energy particles will arrive with larger time delay ( g. sigl - private communication ) . in the case of galactic cosmic rays , the propelled wind consists of the crust material of the parent ns ; the rigidity ( @xmath127 ) implies that the heavy nuclei would leak out of the galaxy at a lower rate than that of protons . we thus expect an increase of the heavy - nuclei - to - hydrogen ratio in the chemical composition over time scales of some ten thousand years for cosmic rays originating in qne . note , however , that this is effect is local and could have importance only if we detect a nearby quark star . if the star has undergone a qn phase in the past , the local cosmic ray composition may reflect the time passed since the qn explosion . the cosmic ray acceleration in the qn model consists of three different components as illustrated in figure 1 . the first component is due to the acceleration of the high energy particles in the pulsar wind bubble by the qn shock . we predict few hundred uhecr events above @xmath5 ev for the pierre auger detector per a distant qn , while some thousands are predicted for the proposed euso and owl detectors . magnetic fields can lead into clustering of the predicted events with timescales spread from years to millions of years . the second component stems from qne with the compact remnant born in the propeller regime ( pulsars with high magnetic field and small period undergoing a qn explosion immediately following a sn ) ejecting relativistic particles with @xmath128 . the particles with @xmath145 will eventually interact with the qn shock , as to reach roughly @xmath102 ev ( protons ) and @xmath3 ev ( iron ) in one shock crossing . given the energy of the qn shock , only a tiny amount of the propelled wind particles can be accelerated , i.e. a maximum of @xmath146 particles around the knee energy ( see eq . [ mwrays ] ) . the propelled particles that were not accelerated by the qn shock are injected into the galactic space and will eventually become accelerated by the supernova shocks in the galaxy . qne as possible uhecr sources seem to account for the observed extragalactic flux and can contribute partially ( a few percent ) to the galactic cosmic rays . we conclude by stating that despite the fact that there is no guarantee that qne occur in nature , the model possesses features that can be tested in future cosmic ray detectors . we thank the anonymous referee for the constructive comments that challenged our cosmic ray model and that helped us improve it . pk and ro express their gratitude to the department of physics at the university of jyvskyl , the helsinki university observatory and the science institute of the university of iceland for hospitality . pk acknowledges the hospitality of the university of calgary in the final stages of this work . the research of ro is supported by an operating grant from the natural science and engineering research council of canada ( nserc ) , as well as the alberta ingenuity fund ( aif ) . jm is supported by the academy of finland under the contracts no . 104915 and 107293 , and pk under the contract no . 106570 . pk is also supported by the european union regional development fund . xu , r. 2003 , in stellar astrophysics - a tribute to helmut a. abt . sixth pacific rim conference , xian , china , 11 - 17 july 2002 . edited by k. s. cheng , k. c. leung and t. p. li ( astrophysics and space science library , vol . 298 , dordrecht : kluwer academic publishers , isbn 1 - 4020 - 1683 - 2 , 2003 , p. 73

we explore acceleration of ions in the quark nova ( qn ) scenario , where a neutron star experiences an explosive phase transition into a quark star ( born in the propeller regime ) . in this picture , two cosmic ray components are isolated : one related to the randomized pulsar wind and the other to the propelled wind , both boosted by the ultra - relativistic quark nova shock . the latter component acquires energies @xmath0 while the former , boosted pulsar wind , achieves ultra - high energies @xmath1 ev . the composition is dominated by ions present in the pulsar wind in the energy range above @xmath2 ev , while at energies below @xmath3 ev the propelled ejecta , consisting of the fall - back neutron star crust material from the explosion , is the dominant one . added to these two components , the propeller injects relativistic particles with lorentz factors @xmath4 , later to be accelerated by galactic supernova shocks . the qn model appears to be able to account for the extragalactic cosmic rays above the ankle and to contribute a few percent of the galactic cosmic rays below the ankle . we predict few hundred ultra - high energy cosmic ray events above @xmath5 ev for the pierre auger detector per distant qn , while some thousands are predicted for the proposed euso and owl detectors .

its deficiency is associated with neurologic , psychiatric , hematologic , cardiovascular , and gastrointestinal manifestations . less commonly , vitamin b12 deficiency results in dermatologic manifestations , including skin hyperpigmentation , hair changes , vitiligo , and angular stomatitis . vitamin b12 deficiency is usually caused by a restrictive vegetarian diet , malnutrition , malabsorption syndromes , congenital disease , gastrectomy , or other gastrointestinal tract diseases . however , it may be also induced by the recreational use of nitrous oxide ( n2o ) , an often forgotten and important link to b12 deficiency in young , healthy individuals . to our knowledge , cases of n2o abuse - induced vitamin b12 deficiency presenting with cutaneous lesions are rare . here , we report the case of a young woman who developed diffuse hyperpigmentation of the skin after 2 years of n2o abuse . a 29-year - old , non - vegetarian woman was admitted to our hospital because of hyperpigmentation over the dorsa of the fingers , toes ( fig . 2a ) , along with intermittent numbness in the plantar region of the foot that began 2 months before admission . the numbness and hypoesthesia were initially limited to the plantar region of the foot ; subsequently , these symptoms ascended to both lower legs 2 weeks before admission . the patient noted weakness in both legs , an unsteady gait , and a tendency to fall when walking . the patient 's medical history was not significant , and her family history was unremarkable . on physical examination , 2a ) , and no rash or dermatitis had preceded the onset of hyperpigmentation . neurological examination revealed weakness based on hyporeflexia in all limbs and the results of manual muscle tests ( mmt 4+/5 ) . impaired pinprick sensations below the second thoracic dermatome , poor joint positions , and vibration sensations over both lower limbs were recorded . in addition to the observed symptoms , the patient reported mild constipation , a bitter taste in the mouth , and hair loss . laboratory investigations revealed normocytic anemia ( hemoglobin , 10.7 g / dl [ normal range , 12.016.0 g / dl ] ; mean corpuscular volume , 94.1 fl [ normal range , 79100 fl ] ) , leukopenia ( white blood count , 4.41 10/l [ normal range , 4.5 1011 10/l ] ) , and thrombocytopenia ( platelet count , 114 10/l [ normal range 150 10400 10/l ] ) . a low vitamin b12 level ( 204 pg / ml [ normal range 211911 pg / ml ] ) and high serum homocysteine level ( 33.35 mol / l [ normal range 3.7013.90 mol / l ] ) were noted . levels of human immunodeficiency virus antibody , the autoimmune profile , and levels of folic acid and endocrine hormones were within the normal ranges . examination of skin biopsy specimens showed basal layer hyperpigmentation with melanin incontinence and focal mild acanthosis . we reevaluated the patient 's medical history , taking into account the possibility of a vitamin b12 deficiency . the frequency of n2o use was half a whipped cream propellant cartridge ( approximately 7.0 liters of n2o may be released from each cartridge ) daily for the last 2 years , and 1 month before admission , this had increased to 1 propellant cartridge daily . the patient received intramuscular injections of 1,000 g vitamin b12 daily for 1 week and then weekly for 1 month . after 4 weeks of treatment , the pigmented lesions showed clinically significant improvement ( fig . vitamin b12 deficiency is associated with cutaneous , neurologic , psychiatric , hematologic , cardiovascular , cutaneous , psychomotor , and gastrointestinal manifestations . many factors can contribute to vitamin b12 deficiency , including a restrictive vegetarian diet , malnutrition , malabsorption syndromes , congenital disease ( i.e. transporter defect ) , postgastrectomy malabsorption , pernicious anemia , and other gastrointestinal tract diseases ( i.e. ileal resection , bacterial overgrowth , and inflammatory bowel disease ) . furthermore , and as seen in our patient , long - term exposure to n2o can induce vitamin b12 deficiency . n2o , a commonly used inhaled anesthetic agent , is not commonly used as a recreational drug . however , n2o is available via the internet and on the street in the form of whipped cream canisters , tanks , or in small cartridges called whippets. the toxicity of n2o is based on its interaction with vitamin b12 and was first reported by banks et al . in 1968 . once n2o is cleaved into free nitrogen and oxygen , it rapidly oxidizes and irreversibly inactivates vitamin b12 . it is a cofactor for 2 important enzymes in humans : methionine synthase and methylmalonyl - coenzyme a ( coa ) mutase . in the cytoplasm , methionine synthase requires the reduced or co(i ) form of vitamin b12 , namely , methylcobalamin , to convert homocysteine to methionine by the transfer of a methyl group from 5-methyltetrahydrofolate . this step retains the methyl donor s - adenosylmethionine for further methylation processes in the methylation cycle and links to the dna synthesis pathway via the generation of tetrahydrofolate from 5-methyltetrahydrofolate . in mitochondria , the oxidized or co(iii ) form of vitamin b12 , namely , 5-deoxyadenosylcobalamin , is required for the mitochondrial enzyme methylmalonyl - coa mutase to convert methylmalonyl - coa to succinyl - coa , which is important in hemoglobin synthesis , the oxidation of odd - chain fatty acids , and the catabolism of ketogenic amino acids [ 6 , 7 ] . the reduced form of vitamin b12 , as noted previously , is an important cofactor for methionine synthase , a key enzyme in dna synthesis and in methylation reactions . n2o - induced oxidation of vitamin b12 converts vitamin b12 from a reduced to an oxidized form , which inhibits the activity of methionine synthase , leading to impairment of methylation reactions and dna synthesis . however , the methylmalonyl - coa mutase pathway is not affected because this pathway depends on the oxidized form rather than the reduced form of vitamin b12 . hyperpigmentation of the skin with megaloblastic anemia associated with vitamin b12 deficiency was first observed by cook in 1944 [ 9 , 10 , 11 ] . pigmentation due to vitamin b12 deficiency can occur at any location on the body , but it occurs most commonly on the hands and feet , particularly in the interphalangeal joints , and sometimes in the fingernails and toenails . gilliam and cox postulated that vitamin b12 deficiency leads to lower intracellular levels of reduced - type glutathione , which has a tyrosinase - inhibiting effect , and that once this effect declines , the epidermal melanocytes are stimulated to produce melanin . moreover , the decreased reduced - type glutathione concentration retards mitosis and reduces dna synthesis , causing dermal atrophy and hyperpigmentation . however , the reasons underlying the predominant occurrence of pigmentation in specific areas and its occurrence in only certain cases need further investigation . n2o - induced neuropathy was initially recognized by layzer et al . in 1978 . in that study , the common initial symptoms were numbness of the distal limbs and imbalance , complicated by weakness in the lower extremities , with some patients becoming too unsteady to walk without assistance . the numbness sometimes travelled upwards from the feet and also caused clumsiness in the hands . physical examination of the patients revealed diminished deep tendon reflexes of the lower legs , positive babinski sign , loss of sensation in the dorsal columns , and a wide - based gait . these neurological manifestations were induced by the interaction of n2o with vitamin b12 and did not resolve until n2o exposure was discontinued . n2o - induced oxidation of vitamin b12 is irreversible , and recovery of methionine synthase activity requires the reduced form of vitamin b12 to be newly synthesized . after discontinuation of n2o exposure and provision of adequate treatment , previous studies have shown that normal enzyme activity recovers within 34 days . in the present case , the clinical features of multiple hyperpigmented macular patches on the skin , myeloneuropathy , loss of sensation in the posterior column , poor balance , and pancytopenia were consistent with the diagnosis of vitamin b12 deficiency . moreover , laboratory studies revealed elevated serum homocysteine levels and polyneuropathy in both lower limbs , which further confirmed the diagnosis of b12 deficiency . the treatment of n2o abuse - induced vitamin b12 deficiency is similar to the treatment of pernicious anemia , and comprises 1 of 2 regimens : ( 1 ) intramuscular injections of 1,000 g vitamin b12 ( cyanocobalamin ) daily for 1 week , followed by weekly injections for 48 weeks , and then monthly injections until clinical resolution ; or ( 2 ) daily oral administration of 1,0002,000 g cyanocobalamin until clinical resolution . our patient , a well - nourished young woman diagnosed with vitamin b12 deficiency , had hyperpigmentation over the dorsa of the fingers , toes , and trunk , associated with pancytopenia and myeloneuropathy . unlike previously reported cases [ 10 , 11 ] , there were no malabsorption syndromes , nor was there malnutrition or any other gastrointestinal causes . the hyperpigmented lesions improved with daily intramuscular injections of 1,000 g cyanocobalamin and cessation of n2o abuse . n2o abuse may induce vitamin b12 deficiency , leading to hyperpigmentation of the skin , hair changes , megaloblastic anemia , pancytopenia , subacute combined degeneration , depression , psychosis , and a possible increased risk of myocardial infarction and stroke ; however , many of these symptoms , including hyperpigmentation , are reversible with vitamin b12 supplementation . it is important for clinicians to recognize the manifestations of n2o abuse and begin treatment as early as possible . this case report has important diagnostic implications in relation to presentations of skin pigmentation in association with neuropathy . when vitamin b12 deficiency occurs in healthy individuals in the absence of gastrointestinal causes , malnutrition , and malabsorption , n2o exposure should be considered in the differential diagnosis . a detailed and complete patient history is crucial for establishing the diagnosis of n2o intoxication - induced vitamin b12 deficiency .

vitamin b12 deficiency causes skin hyperpigmentation , subacute combined degeneration of the spinal cord , and megaloblastic anemia . although vitamin b12 deficiency rarely occurs in well - nourished , healthy , young people , nitrous oxide ( n2o ) intoxication is an important cause of vitamin b12 deficiency in this cohort . n2o , a colorless gas used as an anesthetic since the late 19th century because of its euphoric and analgesic qualities , is now used as a recreational drug and is available via the internet and at clubs . here , we describe the case of a 29-year - old woman presenting with skin hyperpigmentation as her only initial symptom after n2o abuse for approximately 2 years . n2o intoxication - induced vitamin b12 deficiency was diagnosed based on the skin pigmentation that had manifested over the dorsa of her fingers , toes , and trunk , coupled with myeloneuropathy of the posterior and lateral columns , a low serum vitamin b12 level , an elevated serum homocysteine level , and the n2o exposure revealed while establishing the patient 's history . symptoms improved significantly with vitamin b12 treatment . we recommend that dermatologists consider n2o intoxication - induced vitamin b12 deficiency as a potential cause of skin hyperpigmentation and myeloneuropathy of the posterior and lateral columns in young , otherwise healthy patients . failure to recognize this presentation may result in inappropriate treatment , thus affecting patients clinical outcomes .

the human skin is the body s main interface with the external world ; the skin is the site of events and processes crucial to the way we think about , feel about , and interact with one another.13 it can thus be regarded as the body s major public relations tool . conditions which affect the skin may , therefore , affect an individual s ability to function properly in society,4 more on account of the negative psychological impact than from the presence of disease . acne vulgaris is one such condition , primarily seen in adolescents and often with a definite and limited course . its onset coincides with the period of the development of the secondary sexual characteristics and may add to the emotional and psychological challenges experienced during this period.5 the world health organization ( who ) defines quality of life ( qol ) as the individual s perception of their position in life in the context of the culture and value systems in which they live , and in relation to their goals , expectations , standards , and concerns . it is a broad - ranging concept , affected in a complex way by the person s physical health , psychological state , level of independence , social relationships , personal beliefs , and their relationship to salient features of their environment.6 the measurement of qol has been recognized as being of crucial importance in the assessment and management of diseases.7 a number of instruments have been designed to determine the impact of diseases on the qol of individuals ; some are generic and others specific to particular disease entities . acne vulgaris is very common in adolescents in nigeria , with a prevalence ranging from 35%90.7%810 in community - based surveys across the nation ; it has also consistently ranked among the ten most common reasons for consultations in dermatologic outpatient clinics in both the northern and southern parts of the country.1113 it has been found to have a significant negative impact on the health - related qol of adolescents;14 however , little is known of its effect on the qol of nigerian adolescents . employing an instrument which has not been validated , yahya10 found that the condition had little or no impact on the daily lives of adolescents in kaduna , northern nigeria . we have thus employed a slightly modified english version of the cardiff acne disability index ( cadi ) a well validated acne instrument derived from a much longer one by motley and finlay15 to assess the impact of acne vulgaris on in - school adolescents in lagos state . it is the smallest , yet most populous multiethnic city in the country.16 this is due to its having been the capital of nigeria from 19141991 , after which the capital was moved to abuja . this was a cross - sectional survey conducted over a 3-week period , between january and february 2009 , among all eligible senior secondary school adolescents in mushin , a densely populated suburb of lagos state . it involved a two - stage , random sampling method , in which the study area ( mushin ) was randomly selected out of the 20 local government areas in lagos state.18 thereafter , one school was randomly selected from the 17 eligible schools ( eligibility criteria : senior secondary , coeducational , day school ) . the sample size for the study was calculated , and a minimum sample size of 141 was obtained ( including a 10% attrition rate ) ; this was increased to 160 . seven hundred and twenty eight students completed a semistructured questionnaire , providing information such as biodata , history , and characterization of acne , health - seeking behavior , therapies employed in the treatment of acne , and sources of therapeutic agents . the students were then examined for the presence of acne . among those with acne , 160 consecutive students had their acne severity graded using the global acne grading scale ( gags ) . this grading scale calculates the severity of acne through the combined assessment of the types of acne lesions ( comedones , papules , pustules , and nodules ) and their anatomic location ( forehead , cheeks , nose , chin , chest , and back ) . the gags score ranges from 0 ( no acne ) , 118 ( mild acne ) , 1930 ( moderate acne ) , 3138 ( severe acne ) , and 39 ( very severe acne ) . students also completed a second interviewer - administered questionnaire : the cadi , which contains five questions , each with likert - type options assessing emotional , social , and psychological consequences , in addition to subjectively assessing the severity of their acne . the total score for all five questions range from 015 , and for the purpose of this study , they were categorized into 0 ( no impairment from acne ) , 15 ( mild impairment from acne ) , 610 ( moderate impairment from acne ) , and 1115 ( severe impairment from acne ) . the data generated were analyzed using the statistical package for the social sciences software , version 17 ( spss inc . , simple tables were used to show the variables obtained . the chi - square test and fisher s exact test ( the latter for n values less than 5 ) were used to analyze statistically significant difference of variables , and the spearman correlation coefficient test was used for correlation between the variables ; p - value less than 0.05 was accepted as being statistically significant . ethical clearance was obtained from the research and ethics committee of the lagos university teaching hospital , and permission was also obtained from the mushin local government area and school authorities . a total of 160 students with acne vulgaris were assessed , comprising 83 males and 77 females , with a mean age of 16.11.5 years ( mean standard deviation [ sd ] ) . analysis of the questionnaires filled out by all 728 students prior to physical examination revealed that 42% of the 160 subjects with acne had earlier denied having acne . the majority of students ( 89.4% ) had mild acne while 10.0% had moderate acne , with more females being affected in this grade . there was only one case of severe acne , and this was in a male student . the difference between the sexes in terms of severity of acne was statistically significant , with females having a higher grade of acne severity compared to males ( =5.97 , p=0.03 ) ( table 1 ) . males were more likely to have treated acne ( 72.2% ) compared to their female counterparts ( 59.8% ) ; however , more females ( 28.6% ) were found to have treated with topical steroids than males ( 23.4% ) . there were varying degrees of acne - induced qol impairment , and 15% of respondents had no impairment in qol , even though they had different grades of acne severity . the cadi score showed that 85% of respondents were , to varying degrees , negatively affected by the presence of acne ; 61.2% had mild , 21.5% had moderate , and 2.5% had severe impairment in qol . the mean overall cadi score was 3.43.0 , with a mean score of 3.83.2 in males and 3.12.7 in females . analysis of the individual cadi questions showed that 43.9% of the respondents expressed negative emotions as a result of having acne ; 21.9% had some impairment in social interactions , 14.4% would not publicly expose extrafacial areas affected by acne , 64.4% were in some way psychologically affected by acne , and 71.9% thought their acne was a problem . there was a statistically significant , weak positive correlation between acne severity and cadi ( r=0.24 , p=0.003 ) ( figure 1 ) . acne vulgaris is a common skin disease among adolescents , thus it is curious that 42% of our subjects had initially denied having acne . this is similar to the result from a survey in northern nigeria , where up to 40% of students with acne in a secondary school reported the contrary.10 this may stem from a true unawareness , denial , or a reluctance to be branded as having the same disease as persons with more severe forms of acne . in a brazilian study among male adolescents with acne , almeida et al19 reported that the prevalence of active acne obtained by dermatological examination was higher than that for self - reported acne , concluding that self - reporting of acne in adolescents is an inadequate instrument for epidemiological studies . the vast majority of students had mild acne , and a little over 10% had moderate / severe acne . a similar pattern was obtained in comparative studies by yahya10 in kaduna , and hanisah et al20 in malaysia . however , tan et al21 obtained a near equal prevalence of moderate / severe acne ( 48.6% ) and mild acne ( 51.4% ) in singaporean adolescents . in hospital - based studies , agheai et al22 found more moderate / severe grades of acne ( 84% ) compared to mild grades ( 16% ) , and so did mallon et al23 in the uk . this is not unexpected , as persons with more severe diseases are likely to seek medical intervention , thus hospital - based studies are likely to yield more severe forms of acne compared to community - based ones such as ours . in our study , females were surprisingly found to have more severe forms of acne than males although the solitary student with severe acne was male . this is contrary to the widely held view that acne is more severe in males , as shown in the surveys by hanisah et al20 and by aktan et al24 in turkish high school students . a probable reason for our findings may be the more frequent use of steroid - containing creams for the treatment of acne , a practice which was more common among females . the use of topical steroid for skin bleaching is common in our environment , more so in females than in males . this has been associated with the development of steroid acne.25 the overall cadi score was 3.43.0 , indicating a mild degree of disability from acne . similar values were obtained in some community - based studies20,26 while higher scores of 6.5 and 6 were obtained by motley and finlay15 in the uk and oakley27 in new zealand , respectively . several reasons may be adduced for the relatively higher cadi scores in the two latter studies , which were hospital - based : firstly , hospital - based studies have a higher concentration of persons with more severe grades of acne compared to community - based surveys . secondly , the ages of patients in hospital - based surveys are varied compared to the exclusively adolescent age of the aforementioned community - based studies . another factor may be cultural and/or racial ; the studies with higher cadi scores were conducted in western societies.15,27 the marked emphasis placed on body image in these societies ( mostly fueled by external cues such as the media ) and the observed greater satisfaction and more positive perception of body image among black women compared to whites28 may also account for the disparities in the cadi scores . this line of reasoning is , however , controverted by the very low cadi score ( 1.9 ) obtained by walker and lewis - jones29 in a community - based survey of scottish school children . certain questions in the cadi questionnaire were observed to have more impact on our subjects than others . fewer persons ( 14.4% ) were affected by question 3 , which alluded to the presence of acne on extrafacial areas . this was also the observation in malaysia.20 this may either imply that extrafacial acne is uncommon , thus persons without such lesions are in no way affected ; or that the presence of such lesions has no effect on the respondents utilization of public changing facilities or mode of dressing ; or even that the question is not relevant to the vast majority of respondents who probably have no need to use public changing facilities as they neither take part in outdoor sports or swimming . the highest percentage of respondents with qol impairment were found in questions 4 and 5 , which revealed that 64.4% ( question 4 ) were psychologically perturbed by the appearance of their skin , and 71.9% ( question 5 ) thought their acne was a problem . these questions also elicited the highest percentage of responses from studies by hanisah et al20 and peri et al,26 implying that these questions allowed for a greater degree of problem articulation than others . this is similar to the findings by law et al,30 who recorded that the clinical severity of acne did not correlate strongly with the effect on qol this may imply that impairment in the qol of adolescents is not solely determined by acne severity ( reason why some adolescents with mild acne present with marked qol impairment and others with moderate / severe acne record little or no impact on their qol ) or that the cadi instrument ( generated in a western society ) may not be adequately structured to measure the psychosocial impact of acne severity in our nigerian adolescents . this is against the backdrop that man is a product of his environment ; thus , the culture and value systems of a given society affect the perception and concerns of members of that society as inferred in the who definition of qol.6 there is , thus , a need for more local studies to ascertain the validity of the cadi instrument in assessing the psychosocial impact of acne on nigerian adolescents . the major limitation of this study is that it was conducted among adolescents in a public school in lagos and may not reflect the findings in more affluent adolescents , most of whom attend private schools . also , since causality can not be inferred in cross - sectional surveys , it is difficult to implicate acne as the sole cause of the qol impairment . in addition , some factors which can influence the impact of acne in adolescents in our environment , such as the socioeconomic status and ethnicities of the respondents and their relationship to qol , were not assessed . however , the examination of the students to ascertain the actual presence or absence of acne precluded our reliance on self - reported acne , which has been found to be an inadequate instrument in epidemiologic surveys . although the impact of acne on the qol of adolescents in lagos is mild , the use of qol measures is important to identify persons psychologically affected by the disease . there is a need for more studies to validate the existing qol instruments in the nigerian population ; this may be a preface to the modification of existing instruments or the generation of new ones structured to suit the values and culture of our society .

backgroundacne vulgaris is a common skin condition , which affects most adolescents at some point in their lives . it has been found to have a significant impact on their psychological well - being and has been associated with depression and suicide ideation . many studies have assessed the impact of acne vulgaris on the quality of life ( qol ) in different population subgroups around the world , but there is a dearth of reports from the african subcontinent . this study thus seeks to assess the severity of acne vulgaris and determine its effect on the qol of adolescents in lagos , nigeria.methodsin a cross - sectional survey employing a two - stage sampling method , the severity of acne vulgaris and its impact on the qol of adolescents attending a senior secondary school in lagos , nigeria was assessed using the global acne grading scale ( gags ) and the cardiff acne disability index ( cadi ) , respectively . the correlation between the results of the gags and cadi was also determined.resultsone hundred and sixty adolescent students with acne were recruited , with males accounting for 51.9% and females 48.1% . the mean and standard deviation of the gags severity scores were 11.35.4 for males and 11.95.4 for females . only one student had severe acne vulgaris ( gags , 3138 ) , 10% moderate ( gags , 1930 ) , and 89.4% mild ( gags , 118 ) . the overall cadi score was 3.43.0 , which suggests mild impairment in qol ; however , the solitary student with severe acne had severe qol impairment . there was a weak positive correlation between the gags and the cadi score.conclusionmost adolescents in our study had mild acne vulgaris , and the overall impact on their qol was mild . however , the correlation between the psychosocial impact and acne severity was weak . there is a need for similar studies in other parts of the country and for further studies to determine the adequacy of the existing instruments in assessing the impact of acne vulgaris in nigerian adolescents .

Sunday started out as a normal day waiting tables for Claire Hudson. The 25-year-old was working a double shift for her job at local burger joint, Mac's Grub Shak, when something amazing happened. "It was actually a really slow day and then this couple came in," said Hudson of Spring Hill, Tennessee. "I didn’t even realize the tip until after they were gone." The unidentified diners had left a $36 tip on a bill that couldn't have been more than $30, Hudson told ABC News. "I would’ve liked to have caught them and said 'hey this is awesome!,' she said. "They did it anonymously and it was really sweet." In addition to the $36, the couple also left Hudson with a note explaining the heartfelt meaning behind the digits. "Today is my brother's b-day," it said, written behind the credit card receipt. "He would have been 36 today. Every year I go eat his favorite meal (hot dogs) and tip the waitress his age. Happy B-day Wes." Claire Hudson "I was in tears when I read it," Hudson said. "I had to go in the back of the restaurant and compose myself before I went out to my other tables." About three hours after the experience, Hudson posted an image of her customer's note on Reddit. "When I woke up I was on the front page," she said. "It had over 1.5 million views on Imgur and 350K upvotes on Reddit." In light of her story going viral, Hudson and the restaurant owner hope to track down the kind patron that left the tip. "We want to see what his brother Wes liked on his hot dogs because we'd like to name a hot dog after him," she said. "I have a friend, he was my best friend, he died about three years ago. This experience has definitely given me the idea to do the same thing on his birthday every year. It was deeply moving and just the coolest thing that’s ever happened." ||||| The hit HLN Original Series series, Something's Killing Me with BD Wong, investigates puzzling and sometimes fatal medical cases, where life literally hangs in the balance. Each week physicians and scientists race against time to solve the mystery that will save their patient's life. Through six one-hour episodes, family members, medical experts and CNN correspondents, including CNN Chief Medical Correspondent Dr. Sanjay Gupta and Senior Medical Correspondent Elizabeth Cohen, take viewers through the twists and turns of real, heart pounding stories. ||||| Good News Waitress shares the heartwarming way a customer honored his late brother March 10, 2015 at 4:24 PM ET Claire Hudson got the best tip of her life this week, but it wasn't about the money. At first, the 25-year-old waitress at Mac's Grub Shack in Spring Hill, Tennessee didn't even notice the note scrawled on the back of the receipt left by a "very sweet couple" who'd ordered beers, a burger and hot dogs. Courtesy of Claire Hudson "Today is my brother's b-day," read the note. "He would have been 36 today. Every year I go eat his favorite meal (hot dogs) and tip the waitress his age. Happy b-day Wes." Hudson says she was "deeply moved" by the message. "I didn't even see their receipt until after they left!" she told TODAY.com. "I've been a server for several years and this is the best tip I've ever gotten," she added. "Not because of the money, but because of the meaning." Courtesy of Claire Hudson She posted the picture to Reddit, where it quickly got noticed, as people were moved by the story. "I love Reddit and felt like it was a great picture that should be shared," she said. "I had no idea it would get that much attention! I think it's fantastic that so many people liked it, but I mainly wanted to share the sweet memory." Hudson hopes they can give the diner a lasting legacy for his brother, in food form. "The owner of my restaurant, Michael McCray, is trying to contact the patrons and find out what Wes liked on his hot dogs so we can add it to the menu," she said.

– A waitress in Tennessee was brought to tears this week when a customer left her a generous tip and a moving message. Claire Hudson, 25, was serving tables at Mac's Grub Shak in Spring Hill on Sunday when a "very sweet couple" sat down and ordered beers, a burger, and hot dogs, Today.com reports. It was only after they left that a cashier pointed out the $36 tip the man had left on his $28.12 bill, along with a note on the back. "I didn't know what to say," Hudson tells ABC News. "I was in tears when I read it." It read: "Today is my brother's b-day. He would have been 36 today. Every year I go eat his favorite meal (hot dogs) and tip the waitress his age. Happy B-day Wes." "It's the best tip I've ever gotten," Hudson says, "not because of the money, but because of the meaning." Hudson posted a photo of the bill on Reddit after she finished up her shift that night. "When I woke up I was on the front page," she says. "It had over 1.5 million views on Imgur and 350,000 upvotes on Reddit." Hudson and the owner of Mac's Grub Shak now want to honor the man that inspired the generous gratuity. They hope to track down the tipper to find out exactly what Wes liked on his hot dogs so the eatery can "name a hot dog after him." Hudson adds she may start a similar tradition herself. "My best friend, he died about three years ago. This experience has definitely given me the idea to do the same thing on his birthday every year," she says. "It was deeply moving and just the coolest thing that's ever happened." (This waitress got a big tip just when she really needed it.)

over the past 30 years , the genetic basis of cancer has been firmly established , from knudson s two - hit hypothesis to the identification of numerous specific mutations characterized as oncogenes and suppressor genes . attempts to repair or replace mutated genes , by gene therapy have been hindered not only by technical difficulties in delivery , but , more importantly , by the redundancy and plasticity of the cancer genome . in this regard , the discoveries in cancer epigenetics offer new opportunities and strategies . for this point - of - view , epigenetic mechanisms refer to those structural and enzymatic interactions that regulate transcription independently of the dna primary sequence . we will focus on the links between epigenetics and the metabolic mechanisms mediating adjustments to the tumor microenvironment . the expression of genes is modulated by the interaction between dna and chromatin , including acetylation of histones and methylation of both dna and histones . a number of excellent reviews describe the families of histone and dna methylases , and the histone acetylases and deacetylases . thus , cancer genetics not only depends on mutations in the primary sequence of oncogenes and suppressor genes , but also on subsequent gene regulation . importantly , the expression of genes downstream from oncogenes and suppressor genes are ultimately dependent on these regulated modifications of dna and histones . although mutations have been found in the genes encoding dna / histone modifying enzymes , targeting them for repair or replacement faces the same obstacles as therapy directed against primary oncogenes or suppressor genes . importantly , as pointed out in recent reviews , the modulation of the epigenome by these enzymes depends on the level of metabolic intermediates and cofactors . they could be considered a minute - by - minute sensing mechanism of the cellular metabolic state . examples of these linkages include the metabolism - dependent fluctuations in acetyl coa , the substrate for histone acetyltransferases . on the other hand , sirtuins remove acetyl groups from lysine in histones requiring nad , a sensitive and dynamic indicator of energy metabolism . methylation of both dna and histones by their respective methyltransferases requires 1-carbon transfers from s - adenosylmethionine whereas tet2- and jmdh2-mediated demethylation depends , in large part , on -ketoglutarate ( -kg ) as substrate for -kg dioxygenases for oxidizing methyl - cytosine to hydroxymethyl - cytosine . thus , epigenetic enzymes not only depend on metabolites but they regulate genes which reprogram metabolism . about 15 years ago , the resurgence of research interest led to the identification of reprogramming in metabolism in cancer . but , instead , are the integrated responses to driver genes such as c - myc and pi3k / pten . the constellation of metabolic changes in cancer cells includes aerobic glycolysis first described by warburg , changes in tca cycle function , activation of the pentose phosphate pathway and the addiction to glutamine . an attractive explanation is the rerouting of glucose and glutamine into pathways generating substrates ( amino acids , ribonucleotides and lipids ) for building cell mass . however , the success of this strategy was limited presumably because these core pathways have numerous compensatory mechanisms , including the network of endocrine factors providing homeostatic compensation . the emphasis on the core metabolic pathways for glucose and glutamine metabolism in tumor cells is understandable since addiction to glucose and glutamine has been demonstrated . however , recent discoveries that a number of non - essential amino acids play a critical role in cancer metabolism deserve consideration . non - essential amino acids ( neaa ) may not be important nutritionally , but may make critical contributions to metabolism . prokaryotes can synthesize every proteinogenic amino acid but , as organisms evolved to consume other organisms , this biosynthetic capability is no longer necessary . for example , the biosynthesis of arginine is involved in the incorporation of ammonia into urea and the biosynthesis of cysteine is a product in the degradation of homocysteine , an important component of the pathway for generating s - adenosylmethionine . alanine , aspartic acid and glutamic acid are amino acid analogs of metabolically important keto - acids . recently , the syntheses of glycine and serine have been identified as essential for tumor growth . glutamine is critical for de novo purine and pyrimidine synthesis as well as a source of tca cycle intermediates . in the physiologic setting , glutamine is the currency for transferring carbons and nitrogens from proteolysis to central tissues for further carbon and nitrogen processing . the tiny genome of cryptosporidium , a protozoan parasite found in human intestine , lacks genes for the tca cycle and biosynthetic pathways to sugars and nucleotides , yet it has the synthetic pathways for asparagine , glutamine , glycine and proline . in fact , proline biosynthesis is retained from s. cerevisiae , d. discoidem to h. sapiens . the functions of these aforementioned neaa are recognized , but the utility of the pathway to proline is not immediately obvious . however , work from our laboratory has shown important functions for proline metabolism to explain the basis for its evolutionary conservation . to understand the regulatory functions of neaa , we must introduce a parametabolic paradigm ( fig . 1 ) . for most biosynthetic pathways , the enzyme is regulated to produce a specific product from a precursor . however , for those in the pathways for neaa , the specific aa is the by - product of coupled reactions . an example of this is in the serine metabolic pathway , where the conversion of serine and glycine transfers a carbon group to tetrahydrofolate and 5-methyltetrahydrofolate regenerates methionine from homocysteine . in an atp - dependent reaction , methionine is converted to s - adenosylmethionine , which is the principal methyl donor for biosynthesis of a variety of intermediates as well as the methylation of dna . in the case of neaa participating in transaminations , one endpoint is the transfer of reducing potential across mitochondrial membranes ; for example , the malate - aspartate shuttle . proposed parametabolic regulation by neaa metabolism this cartoon is a representation of a generic parametabolic scheme . the conversion of a to b yields a non - essential amino acid and this step may be upregulated by cancer reprogramming . i1 and i2 are in a metabolic interlock with the conversion of s to m , which is then used for epigenetic modification of dna or chromatin . for example , if a is serine and b is glycine , the reaction is coupled to the conversion of tetrahydrofolate ( thf ) to 5,10-methylene thf , which as 5-methyl thf , transfers methyl groups to homocysteine forming methionine . in the presence of atp , s - adenosylmethionine is formed for dna methylation . in another example , if pyrroline-5-carboxylate , a , is converted to proline , b , nadh , i1 , is oxidized to nad , i2 , which can accept acetyl groups hydrolyzed from histone lysines by sirtuins to form acetyl - adp - ribose . acetylation of histones is dependent on the availability of acetyl - coa , and levels of acetyl - coa can fluctuate as much as 10-fold ; its metabolism primarily reflects the abundance of glucose and the flux through glucose metabolic pathways . on the other hand , the production of serine from 3-phosphoglycerate is promoted by the shift of pyruvate kinase isozymes from pk to pkm2 . the latter has much lower catalytic activity , allowing the buildup of phosphoenolpyruvate and 3-phosphoglycerate . thus , the augmented production of serine would accommodate the substrates for production of sam and methylation . these observations suggest that for some of the neaa , their metabolic pathway serves as a parametabolic link between metabolism and epigenetics . an intriguing question is whether the metabolism of the non - essential amino acid proline also plays such a parametabolic role and whether the proline regulatory axis plays a role not only in the metabolism of core substrates , such as glucose or glutamine , but also in regulating epigenetics . with its -nitrogen sequestered within a pyrrolidine ring , proline is not a substrate for generic amino acid metabolizing enzymes . of special interest , proline dehydrogenase ( oxidase ) is bound to mitochondrial inner membranes . although the catalytic product of the reaction pyrroline-5-carboxylate ( p5c ) can be sequentially converted to glutamate and -kg , an epigenetic metabolite , electrons from proline are donated to the mitochondrial electron transport chain accompanying the production of p5c . in addition , this enzyme is under diverse regulation making it an ideal candidate as an epigenetic regulator . it is robustly and rapidly induced by p53 and by ppar , leading to ros generation , cell cycle arrest , apoptosis and , depending on the cellular context , prosurvival autophagy . the enzyme is upregulated by ampk but downregulated by a specific microrna , mir-23b * , which in turn is modulated by c - myc . furthermore , the discovery that coq is the acceptor for proline - derived electrons(ref . 47 and hancock , unpublished results ) enabled redox signaling proposed by others through complex iii . as first pointed out by adams , p5c is not only the committed precursor for proline but also its immediate degradative product . the cycling was thought to function in a metabolic interlock with the oxidative arm of the pentose phosphate pathway , but recent findings by our lab and others have added several additional functions to the original hypothesis ( liu et al . , unpublished results ) . mutations in prodh in humans may be associated with hyperprolinemia and neuropsychiatric disorders , but the clinical reports are controversial . metabolic findings may be masked by the overlap in redox function between prodh / pox and hydroxyproline oxidase prodh2/hypox . we have shown that the enzymes in the pathway from glutamine to proline catalyzed sequentially by glutaminase ( gls ) , pyrroline-5-carboxylate synthase ( p5cs ) and pyrroline-5 carboxylate reductase 1 ( pycr1 ) are markedly increased by the oncogene c - myc . this response occurred in the face of physiologic concentrations of medium proline ; others have shown the net synthesis of proline by cultured cells resulting in an increase in medium proline concentration . therefore , the upregulation of the proline synthetic pathway by c - myc is not to meet demands for protein synthesis . these findings are consistent with the observations of windmueller et al . , which demonstrate intestines containing proliferating cells primarily use glutamine and our findings showed that the enzymes of this pathway are markedly upregulated by c - myc with correspondingly increased flux demonstrated by stable isotope - resolved metabolomics . humans with pycr1 mutation have altered mitochondrial function and progeroid changes in connective tissues , including cutis laxa . these findings can not be explained on the basis of inadequate proline for protein synthesis . interestingly , the crystal structure for human pycr1 has been solved : the native enzyme is a decamer with a conformation suggesting transporter or chaperone functions . pycr1 appears associated with mitochondrial outer membranes whereas pycr2 is in the matrix and pycrl is in the cytosol . although the localization and properties of these isozymes were shown in melanoma cells and need generalization to other tumors as well as normal tissue , they provide versatility for redox transfers for the proline regulatory axis originating from either proline or from glutamine . deficiency in humans has profound manifestations with progressive neurodegeneration , mental retardation , peripheral neuropathy , joint laxity and cataracts . collagen , the most abundant protein ( by weight ) in the body with 25% of its amino acid residues either as proline or hydroxyproline , can serve as reservoir or metabolic dump for proline . cells starved for substrates increase proline degradation through ampk to provide an alternative mitochondrial substrate and generate ros signals to activate prosurvival autophagy . under conditions of rapid proliferation induced by growth factors and myc activation , proline degradation is downregulated whereas robust induction of p5cs and pycr mediates increased turnover of nad(p)h to nad(p ) ( ref . the increased availability of nadp and nad provides oxidizing potential for critical steps in the oxidative arm of the pentose phosphate pathway and perhaps in glycolysis , respectively . the latter not only spares pyruvate for conversion to other vital intermediates , but nad also supports the activity of sirtuins in deacylating histones . the resultant proline can be incorporated into collagen thereby eliminating it from the metabolome , much as excreted lactate results in the recycling of cellular nadh to nad for glycolysis . although mechano - regulation between collagen fibrils and tumor cells has been proposed , the robust increase in collagen production also provides metabolic advantages for tumor growth . these metabolic features of proline and collagen metabolism may not be provided by a single cell type . in fact , it is likely that asymmetry in metabolism between tumor and stromal cells are a necessary feature . metabolic / signaling collaboration between tissues and/or different cell types have been proposed and an intercellular complementation in proline metabolism between erythrocytes and hepatocytes based on the asymmetry of cellular enzymes has been described . the redox turnover of pyridine nucleotides has been suggested , albeit direct demonstration of the effect requires further studies . since the steady - state ratio of nad(p)h to nad(p ) is difficult to ascertain , the demonstration of turnover can be inferred by flux through pathways in metabolic interlocks . for example with induction of prodh / pox , the flux through the oxidative arm of the pentose phosphate pathway is markedly increased . similarly , with myc - induction of p5cs and pycr1 , glycolysis is markedly increased by c - myc expression . however , in the face of this warburg effect , the knockdown of pycr1 or p5cs markedly inhibited the response ( liu et al . , unpublished results ) . these findings suggest that the proline regulatory axis is providing the redox turnover to optimally activate the c - myc activation of glycolysis . thus , from both proline degradation and proline biosynthesis , we have robust , albeit indirect , evidence of the recycling of pyridine nucleotides and the parametabolic regulation of glucose metabolism . is there experimental evidence that the parametabolic effect of the proline regulatory axis influences epigenetic mechanisms ? certainly , epigenetic changes induced by ros have been demonstrated and reviewed . others have shown that treatment of cultured hepatocellular carcinoma cells with hydrogen peroxide caused methylation of the e - cadherin promoter . we have shown that generation of ros due to upregulation of prodh / pox can activate a parametabolic response or program ranging from downregulation of cox-2 to the activation of prosurvival autophagy depending on the metabolic context . there are a number of published findings from other investigators suggesting that the proline regulatory axis is involved in epigenetics . , using cultured mouse embryonic stem ( es ) cells , showed that of all media constituents , proline uniquely regulated pluripotency . this finding was corroborated by casalino et al . , who showed that the effect of proline in maintaining the metastability of es cells required proline metabolism . another recent example of proline - dependent epigenetic regulation was described by zarse et al . their studies in c. elegans and in mefs showed the life span extension with defective insulin / igf1 ( daf-2 in c. elegans ) signaling was dependent on the catabolism of proline . their interpretation is that the ros generated by proline degradation induces the expression of a genetic program including antioxidant enzymes protecting against ros so that lifespan is extended . in summary , we propose that the metabolism of neaa not only regulates core metabolism , but also produces substrates or cofactors participating in epigenetic mechanisms . thus , the metabolism of neaa acts as a coupling mechanism between metabolomics and epigenetics in cancer . several of the neaa mechanisms involve the cycling of substrates , cofactors or transfer mechanisms necessary for epigenetic regulation . we also introduce parametabolic regulation to understand the metabolic interlocks between neaa and critical core pathways , i.e. , glucose metabolism and ribonucleotides synthesis . we propose that the regulation of the enzymes of the proline regulatory axis provides plasticity in the production of various intermediates as well as in the recycling of pyridine nucleotides ( table 1 ) . we hope that this regulatory axis will offer novel therapeutic targets for the treatment of cancer .

recent research suggests that chromatin - modifying enzymes are metabolic sensors regulating gene expression . epigenetics is linked to metabolomics in response to the cellular microenvironment . specific metabolites involved in this sensing mechanism include s - adenosylmethionine , acetyl - coa , alphaketoglutarate and nad+ . although the core metabolic pathways involving glucose have been emphasized as the source of these metabolites , the reprogramming of pathways involving non - essential amino acids may also play an important role , especially in cancer . examples include metabolic pathways for glutamine , serine and glycine . the coupling of these pathways to the intermediates affecting epigenetic regulation occurs by parametabolic mechanisms . the metabolism of proline may play a special role in this parametabolic linkage between metabolism and epigenetics . both proline degradation and biosynthesis are robustly affected by oncogenes or suppressor genes , and they can modulate intermediates involved in epigenetic regulation . a number of mechanisms in a variety of animal species have been described by our laboratory and by others . the challenge we now face is to identify the specific chromatin - modifying enzymes involved in coupling of proline metabolism to altered reprogramming of gene expression .

there are several reasons @xcite , which make the experimental study of the @xmath3 reaction interesting . first of all , it is expected that the radial excitations of @xmath4-meson should reveal themselves in this process , thus giving us a possibility to study their properties . the @xmath3 transition is also important for the precise determination of the total cross section of @xmath5 annihilation into hadrons . in the vector meson dominance model @xmath3 transition is connected to the @xmath6 vertex , which appears also in a number of hadron decays , like @xmath7 , @xmath8 , @xmath9 , @xmath10 , @xmath11 . the precise experimental data about these processes stimulate theoretical study of the underlying hadron dynamics . in the low energy limit , the chiral perturbation theory @xcite and effective chiral lagrangians @xcite give a phenomenological description of meson physics , as it is commonly believed nowadays . but their applicability is in question for energies above 1 gev . on the other hand , for energies @xmath12 gev , the perturbative qcd is also not applicable . so any precise experimental information in this energy range can be considered as `` data in searching of the theory '' . simple but successful vector meson dominance picture may become insufficient when the precision of the data increases . the @xmath3 transition can be studied in either @xmath13 or @xmath14 channels . the former can provide about one order of magnitude more statistics , but the latter is more preferable concerning background conditions . the @xmath14 reaction was studied earlier in the energy range @xmath15 gev by the nd detector @xcite . indirectly , the @xmath16 cross section was extracted also from the argus data on @xmath17 decay @xcite , under assumption of the conserved vector current ( cvc ) . the results are in good agreement , thus confirming the cvc hypothesis @xcite . in 1995 a new set of experiments began with the snd detector @xcite on the novosibirsk vepp-2 m storage ring @xcite . the maximum luminosity of vepp-2 m at @xmath18 equals @xmath19 . below we report the results on @xmath14 process , based on 1996 - 1997 two - year snd statistics . in 1996 several scans were made of the energy interval @xmath20 @xcite . from the 1997 experiment @xcite a part of statistics , collected at the center of mass energies 980 , 1040 and 1060 mev , was used . as we have already mentioned in the introduction , currently no definite predictions can be made from the basic first - principle theory of strong interactions ( qcd ) in this energy range . the limited accuracy of the existing experimental data leaves enough room for various phenomenologically inspired models . now a light is seen at the end of the tunnel : several meson factories come into operation , and also a new generation of fixed - target experiments will accumulate a huge number of events with strongly interacting particles . so the experimental information is expected to become increasingly precise . of course a common wisdom says that `` if we see a light at the end of the tunnel , it s the light of an oncoming train '' @xcite . so it is not excluded that the present theoretical models will be shattered by this `` train '' , but it can deliver a new passenger also . here we consider a simple phenomenological model , based on the vector meson dominance scheme . our aim is twofold : to estimate the expected cross section and to establish a framework for monte - carlo simulation . let @xmath21 be the matrix element of the electromagnetic current between the vacuum and the @xmath22 final state . then the amplitude for the @xmath23 transition via one - photon annihilation diagram feynman ( 20000,15000 ) ( 550,13000)[8000 ] ( , ) by -2000 ( , ) @xmath24 ( , ) [ 8000 ] ( , ) by -2000 ( , ) @xmath25 ( , ) [ 6 ] ( , ) ( , ) [ 9 ] by 650 ( , ) @xmath26 ( , ) [ 4 ] by 650 ( , ) @xmath27 ( , ) [ 3 ] by 650 ( , ) @xmath28 reads ( up to irrelevant phase factor ) @xmath29 the standard considerations lead to the following cross section with unpolarized beams @xcite @xmath30 where only transverse ( with respect to the beam direction ) components of @xmath31 contribute and the invariant phase space element is @xmath32 @xmath21 should satisfy the current conservation condition @xmath33 . on the other hand @xmath34 , @xmath35 being the photon polarization 4-vector . so @xmath36 is a gauge invariant tensor : @xmath37 there exists a general procedure how to construct such gauge invariant tensors which are free from kinematical singularities @xcite . in our case there are just three independent tensors @xcite @xmath38 + q_\nu [ ( k\cdot q)q_\mu - q^2k_\mu ] . \nonumber \end{aligned}\ ] ] so @xmath39 dimensionless form factors @xmath40 are determined by the concrete dynamical model . summing over the final state photon polarizations ( reduce program @xcite proves to be useful for these calculations ) and performing the angular integration , we get @xcite @xmath41 where ( @xmath42 ) @xmath43 . \nonumber \label{cij } \end{aligned}\ ] ] so for the total cross - section we obtain ( the factor @xmath44 accounts for identical @xmath45 ) @xmath46 the integration limits are determined from the condition @xmath47 which gives @xmath48\ ; . \label{intlim } \end{aligned}\ ] ] to proceed , we need expressions for the @xmath40 form factors . it is expected that the main contribution comes from diagrams of the following type ( 30000,19000 ) ( 550,15000)[8000 ] ( , ) ( , ) [ 8000 ] ( , ) ( , ) [ 6 ] ( , ) ( , ) [ 300 ] ( , ) [ 6000 ] ( , ) [ 300 ] ( , ) [ 6000 ] by 1000 ( , ) @xmath49 ( , ) [ 600 ] ( , ) ( , ) [ 5 ] by 1000 ( , ) @xmath27 by 1000 ( , ) [ 300 ] ( , ) [ 4000 ] ( , ) [ 600 ] ( , ) ( , ) [ 4000 ] by -2000 by 700 ( , ) @xmath50 ( , ) [ 3 ] by 1000 ( , ) @xmath28 by 4000 ( , ) @xmath51 by 3000 ( , ) @xmath52 by 400 ( , ) [ 7 ] by 1000 ( , ) @xmath26 using kinematical structures of the @xmath53 and @xmath54 vertexes , which are determined from the lorentz covariance , we get for the form factors @xcite @xmath55+\frac{1}{4}(x_1-x_2)[g(x_1)-g(x_2 ) ] , \nonumber \\ & & a_2=\frac{1}{4}[g(x_1)+g(x_2 ) ] \ ; \ ; , \ ; \ ; a_3=-\frac{1}{8}[g(x_1)-g(x_2 ) ] \ ; , \label{ai } \end{aligned}\ ] ] where @xmath56 and individual contributions look like ( note that @xmath57 coupling constant is defined as @xmath58 ) @xmath59 to take into account the resonance width dependence on energy , one should replace @xmath60 , @xmath61 being the resonance 4-momentum . @xmath62 can be determined from the @xmath63 decay width . namely @xmath64 using @xmath65 , @xmath66 , and @xmath67 as inputs , we get @xmath68 as for the photon vector meson coupling constant , it can be determined from the @xmath69 width @xmath70 and we get @xmath71 more complex is the situation with @xmath72 coupling constant . assuming vector meson dominance , @xmath6 vertex appears in a number of processes . for example , @xmath63 decay proceeds via ( 30000,15000 ) ( 1000,7500)[300 ] ( , ) [ 6000 ] ( 1000,7500)[300 ] ( , ) [ 6000 ] by 1000 ( , ) @xmath73 ( , ) [ 600 ] ( , ) ( , ) [ 5 ] by 1000 ( , ) @xmath74 by 1000 ( , ) [ 300 ] ( , ) [ 4000 ] ( , ) [ 600 ] ( , ) ( , ) [ 4000 ] by -2000 by 700 ( , ) @xmath49 by 400 ( , ) [ 7 ] by 1000 ( , ) @xmath75 and therefore @xmath76 . so @xmath77 can be determined from @xmath78 and @xmath79 . on the other hand , @xmath11 decay , in the framework of the vector meson dominance , goes through ( 30000,16000 ) ( 10000,8000)[5 ] ( , ) by 1000 by -1000 ( , ) @xmath74 ( , ) [ 300 ] ( , ) [ 4000 ] ( , ) [ 600 ] ( , ) ( , ) [ 4000 ] by -1500 by 700 ( , ) @xmath4 ( , ) [ 7 ] by 1000 ( , ) @xmath80 ( 10000,8000)[300 ] ( , ) [ 4000 ] ( , ) [ 600 ] ( , ) ( , ) [ 4000 ] by -1500 by -700 ( , ) @xmath81 ( , ) [ 7 ] by 1000 ( , ) @xmath82 by 4000 ( , 8000)@xmath83 and therefore @xmath84 so @xmath72 can be extracted from @xmath85 , @xmath86 , and @xmath87 . all these methods for @xmath72 determination give consistent values : @xmath88 but if the value of @xmath72 is extracted from the experimental @xmath89 decay width , assuming that this decay proceeds through @xmath90 intermediate state and that the @xmath91 coupling constant is determined from the @xmath92 , one obtains @xmath93 this is closer to the chiral model prediction @xcite @xmath94 @xmath72 can be estimated also from qcd sum rules @xcite with the result @xmath95 @xcite . in monte - carlo simulation , we have used ( [ gwrp ] ) and @xmath96 , which follows from @xmath97 . these values assume only @xmath4-pole decay mechanism for @xmath98 transition , without a possible @xmath98 contact term @xcite . in fact , the uncertainty in these coupling constants does not effect significantly the monte - carlo estimates for the detection efficiencies . @xmath99 vertex is forbidden by @xmath100-parity , which is negative for all three particles . another way to see this is to notice that it is impossible to construct isospin invariant trilinear coupling between @xmath1 and @xmath81 isosinglets and isovector pion . but the isospin symmetry breaks due to electromagnetic effects and mass difference between u and d quarks . as a result , pure isospin eigenstates @xmath101 and @xmath102 mix and cease to be mass eigenstates . instead we will have a nondiagonal mass matrix @xmath103 mass eigenstates ( physical @xmath4 and @xmath81 mesons ) are mixtures of isospin eigenstates , which for small @xmath4@xmath81 mixing angle @xmath104 ( @xmath105 ) look like @xmath106 the mixing angle @xmath104 is determined from the condition @xmath107 which gives in the first order in @xmath108 and @xmath104 @xcite : @xmath109 here @xcite @xmath110 is the resonance complex mass square . so @xmath111 as for @xmath4@xmath81 mixing amplitude @xmath108 , we will take the value @xmath112 which follows from the pion form factor studies @xcite . since @xmath113 , the presence of the @xmath114 vertex will induce an effective @xmath99 vertex with a coupling constant @xmath115 the described above picture of @xmath4@xmath81 mixing can be trivially generalized to include mixings with the @xmath1 meson also @xcite : @xmath116 due to @xmath1@xmath4 mixing another contribution to the @xmath99 transition will arise @xmath117 because @xmath118 , this latter contribution turns out to be of the same order as @xmath119 . so for the @xmath120 coupling constant we will use @xmath121 the corresponding contribution in @xmath23 is then determined by equation ( 7 ) . the @xmath1@xmath4 mixing parameter @xmath122 can be extracted from the @xmath123 experimental data near the @xmath1-meson @xcite : @xmath124 where @xmath125 is experimentally measured interference magnitude @xcite . taking average values @xmath126 from @xcite , we obtain @xmath127 no definite theoretical predictions exist for @xmath129 meson contribution , nor it is definitely known whether the only one radial excitation gives significant contribution in this energy region . we will use the following parameterization for this part of the @xmath130 function @xmath131 where @xmath132 corresponds to the @xmath4-meson contribution . @xmath133 and @xmath134 parameters were determined by fitting @xmath135 cross section to higher energy experimental data from @xcite . the fit gives the following values : @xmath136 our results of this fit confirms the conclusions of @xcite that the @xmath129 meson contribution is sufficient to describe the existing experimental data in the @xmath137 energy range . note that we use the pdg @xcite values @xmath138 and @xmath139 . to simulate roughly a threshold effect due to the dominant @xmath140 decay of the @xmath141 meson , we have assumed , as in @xcite , that the @xmath141-meson width rises linearly from @xmath142 up to @xmath143 , remaining constant above . using the estimates for various coupling constants given above , the total cross section can be evaluated for @xmath144 reaction . the result is shown on fig.[fig1 ] . note the significant interference effect near @xmath1 meson , although the @xmath1-meson mediated amplitude itself remains small and corresponds to @xmath145 , in consistence with @xcite . the @xmath1@xmath4@xmath81 interference contribution into @xmath99 transition corresponds to br(@xmath146 in excellent agreement with the recent experimental result @xcite @xmath147 , although it should be beared in mind that there may exist also other sources for this transition @xcite snd is a general purpose nonmagnetic detector . this new detector combines advantages of its predecessor nd detector @xcite and famous crystal ball detector @xcite , that is a good uniformity over the solid angle due to the spherical shape , a good @xmath148 and @xmath149 separation due to multilayer structure of the electromagnetic calorimeter , and high hermeticity . the main part of the snd detector ( fig.[snd ] ) is a 3-layer , spherical , highly granulated , nai(tl ) electromagnetic calorimeter @xcite . tracking system , located in the detector center , consists of two coaxial cylindrical drift chambers . in the radial gap between them a 5 mm thick plastic scintillation counter with a wavelength shifter fiber readout is placed . from outside the calorimeter is covered by a thick ( 12 cm ) iron absorber , which attenuates remnants of electromagnetic showers . an outer muon / veto system is located outside the absorber . it consists of sheets of plastic scintillator and streamer tubes . the detailed description of the snd detector can be found elsewhere @xcite . here we repeat only the main points , relevant to this study . each layer of the calorimeter includes 520560 crystals of eight different shapes . most of the crystals have shapes of truncated tetrahedral pyramids . the total solid angle covered by the calorimeter is equal to 0.9 of 4@xmath150 . the remaining space is occupied by magnetic structure elements of the storage ring , mainly by quadrupole lenses . pairs of counters of the first two layers with thickness of 3@xmath151 and 5@xmath151 respectively are sealed together in common containers made of thin ( 0.1 mm ) aluminum foil . in order to improve light collection efficiency and to separate one crystal from another , each crystal is wrapped in aluminized mylar . the gaps between adjacent crystals do not exceed 0.5 mm . the r.m.s . value of the nonuniformity of the light collection efficiency along the crystals is less than 3 % . all the containers are fastened to 5 mm aluminum supporting hemispheres . the outer layer of 6@xmath151 thick counters has a similar design . thus the total thickness of the calorimeter is 13.5@xmath151 ( 35 cm ) of nai(tl ) . as photosensitive devices for the calorimeter counters vacuum phototriodes are used @xcite . the quantum efficiency of their photocathodes is about 15 % , average gain is 10 , and light collection efficiency for individual counters is about 10 % . signals from phototriodes are amplified by charge sensitive preamplifiers located directly on the counters . output signals are carried to shaping amplifiers via 20 m long twisted cables . for the trigger needs the calorimeter crystals are logically organized into `` towers '' . a tower consists of counters located within the same @xmath152 interval in polar and azimuthal directions in all three layers . the number of counters in a tower is 12 at large angles and 6 in the regions close to the beam . in addition to signals from individual counters each tower produces an analog total energy deposition signal and two trigger signals . in order to equalize contributions from different counters into the total energy deposition signal and to obtain equal energy thresholds for trigger signals over the whole calorimeter , all shaping amplifiers are equipped with computer controlled attenuators , allowing to adjust channels gain in steps of 1/255 . the resulting electronics noise is close to 0.3 mev ( r.m.s . ) . the dependence of the calorimeter energy resolution on photon energies was fitted as @xcite @xmath153{e(\mathrm{gev } ) } } \ ; . \nonumber\ ] ] the calorimeter energy resolution is determined mostly by the amount of passive material inside the calorimeter . noticeable contribution comes also from the shower energy leakage due to limited thickness of nai(tl ) and gaps between crystals . it turned out that the nonuniformity of the light collection efficiency in the nai(tl ) crystals of the inner calorimeter layer contributes significantly into energy resolution . the simulation of calorimeter response agrees reasonably well with experiment after these effects are included into simulation program . absolute energy calibration of the calorimeter is performed by using cosmic muons @xcite and bhabha scattering @xcite . the latter process , together with the two - photon annihilation reaction , was also used for the luminosity measurements . the systematic error in the integrated luminosity determination is about 3% . after the calorimeter calibration with @xmath154 events , the photon energies turned out to be biased by about @xmath155 . in order to compensate for this bias , the calibration coefficients for photons were corrected accordingly . the tracking system consists of two cylindrical drift chambers . the length of the chamber closest to the beam is 40 cm , its inner and outer diameters are 4 and 12 cm respectively . the corresponding dimensions of the outer chamber are 25 , 14 and 24 cm . both chambers are divided into 20 jet - type cells in azimuthal plane . each cell contains 5 sense wires . the longitudinal coordinate is measured by the charge division method with an accuracy of 3 mm . in addition , a cathode strip readout for inner and outer layers provides the improvement of the latter value to 0.5 mm . the outer drift chamber improves pattern recognition for multiparticle events . the overall angular resolution of the drift chamber system is 0.5 and 1.7 degrees in azimuthal and polar directions respectively . the impact parameter resolution is 0.5 mm . the solid angle coverage for the inner chamber is 96 % of 4@xmath150 . the snd muon system consists of plastic scintillation counters and streamer tubes @xcite . it is intended mainly for cosmic background suppression for the events without charged particles . the probability of its triggering by the events of the reaction @xmath156 at the maximum available energy is less than 1 % . muons of the process @xmath157 , starting from the beam energy about 500 mev , penetrate through the absorber and hit the muon detector . the three - level trigger of the detector selects events of different types : events with photons only , events with charged particles , and cosmic muon events for the detector calibration . the drift chamber first level trigger ( flt ) searches for tracks in the drift chambers with impact parameter @xmath158 mm . the calorimeter flt uses the total energy deposition in the calorimeter and double coincidences of calorimeter towers with a threshold of 30 mev . detector electronics provides also signals for a second level trigger . but at present the second level trigger proved to be unnecessary and was not implemented , although a slot is left for it in the electronics . the third level trigger ( tlt ) is implemented as a special fast computer code on a main data acquisition computer . it checks events before recording them on tape , rejects cosmic events with charged trigger , and suppresses beam - related background using @xmath159-coordinates of tracks , measured by drift chambers . in addition tlt identifies collinear events of bhabha scattering and 2@xmath75 annihilation . these events are used for monitoring the collider luminosity . snd data acquisition system is based on the fast electronics modules klukva @xcite , developed in binp specially for purpose of the detectors cmd-2 , kedr and snd . analog signals from the detector come to the front - end amplifiers and shapers , located near the detector . then the signals are transmitted via screened twisted pair cables to the digitizing modules ( adc , tdc , etc ) in klukva crates . logical signals from discriminators in klukva crates are collected by the first level trigger interface modules . after 1 @xmath160 , needed for flt decision , flt generates a signal to start digitizing . the contents of klukva digitizing modules are read into the rams of output processor modules ( op ) , located in klukva crates . this procedure finishes in 120 @xmath160 . there are two independent rams for events in each op and one event can be stored in digitizing modules , such a fast buffering greatly decreases dead time . the total dead time in klukva is 200 @xmath160 per event selected by flt . the data from op rams are read by the vax server 3300 through the camac interface modules with the rate of 2 ms / event . the tlt program can process events with a maximum rate of 45hz . finally the processed events are put on 8 mm 5 gb exabyte tapes . a description of the phi96 experiment was published in @xcite . the phi96 experiment was carried out from february 1996 up to january 1997 . seven successive scans were performed in 14 energy points in the range @xmath161 from 980 to 1044 mev . the data sample , which was analyzed , corresponds to an integrated luminosity of @xmath162 , collected by snd in the narrow energy interval near the @xmath1-meson . estimated number of produced @xmath1-mesons equals to @xmath163 . while studying the channel @xmath164 one should be aware about the possible background from the following processes @xmath165 @xmath166 a primary selection of the @xmath14 candidates was done according to following criteria : * the event must contain exactly 5 photons in the calorimeter and have no charged particles , * the azimuthal angle of any final photon lies within the interval @xmath167 , * the total ( normalized over @xmath161 ) energy deposition of final photons is in the range @xmath168 , * the normalized full momentum of the event ( @xmath169 ) is less than 0.15 . the two latter conditions eliminate the main part of the background , originated from the @xmath170 decay , but they do not help much against another background , coming from the process ( [ phietg ] ) . it is interesting to check whether we really have two @xmath74-s in our 5-photon events . it is unlikely for the most energetic photon to come from @xmath74 decay in either ( [ eewpi ] ) , ( [ phietg ] ) or @xmath171 reactions . it is also not likely for @xmath74 to produce the two softest photons . if we discard the corresponding combinations , only two possibilities ( 2,4),(3,5 ) and ( 2,5),(3,4 ) are left for the photons to compose @xmath172s ( photons are arranged according to their energy , the most energetic being the first one ) . a combined 2-dimensional plot of invariant masses of these photon pairs ( @xmath173 versus @xmath174 plus @xmath175 versus @xmath176 ) is shown in fig.[fig3 ] . we clearly see that our 5-photon events are predominantly @xmath177 events also . besides , fig.[fig3 ] illustrates that background ( [ phietg ] ) produces a wider distribution . this can be used for the rejection of this background . for this purpose , a kinematic fit was performed for each 5-photon event under the assumption that there are two @xmath172s in the final state and energy - momentum balance holds within the experimental accuracy . a @xmath178 of this fit ( @xmath179 ) can be used for the background rejection . background from ( [ phietg ] ) simulates @xmath180 events mainly due to loss of photons through the openings in the calorimeter around detector poles and/or merging of close photon pairs . when photons merge in the calorimeter , the corresponding electromagnetic shower is , as a rule , broader in transverse direction than the electromagnetic showers from the single photons . this circumstance can be used to discriminate against merged photons and so against a great deal of background ( [ phietg ] ) . the corresponding parameter ( @xmath181 ) is described in @xcite . a 2-dimensional distributions of our events in the @xmath182 plane , as well as monte - carlo simulated ( [ eewpi ] ) signal events and ( [ phietg ] ) background events ( fig.[fig4 ] ) , indicate that our signal events are almost completely bound in the @xmath183 area . this was confirmed by experimental events outside of the @xmath1-meson , where there should be no background from the process ( [ phietg ] ) . on the basis of these considerations , we have chosen the following two sets ( cut i and cut ii ) of selection criteria for the channel ( [ eewpi ] ) separation ( in addition to the primary selection rules , described above ) : * the normalized full momentum of the event is less than 0.1 ( for cut i ) , * there are two @xmath74-mesons in the event , that is , one can find two distinct pairs of photons with invariant masses within @xmath184 mev from the @xmath74 mass , * @xmath179 , the @xmath178 of the kinematic fit , is less than 20 for cut i , or is less than 40 for looser cut ii , * @xmath181 , the parameter describing the transverse profile of the electromagnetic shower , is less than 0 for cut i , or is less than 20 for cut ii . one more source of background is a recently observed process @xcite : @xmath185 the recoil mass of the photon from this process is peaked at the @xmath186-meson mass and this peculiarity can be used to separate a great deal of such events from the events of process ( [ eewpi ] ) . we have chosen the @xmath187 condition as one more cut to select events from the process ( [ eewpi ] ) , where @xmath188 stands for the photon recoil mass . after applying these cuts , the @xmath81-meson peak is clearly seen in the invariant mass of @xmath74 and @xmath75 ( for each @xmath180 event , from two possible ( @xmath189 ) combinations , the one is taken , which has @xmath190 closest to @xmath191 ) , as it is illustrated by fig.[fig5 ] ( cut i ) . finally , to extract channel ( [ eewpi ] ) , the @xmath192 condition was added to the above mentioned cuts . the @xmath190 histograms were fitted by a function @xmath193 the fit indicates a good agreement between the experiment and simulation . for the 2356 mc events , which passed cut i , the fitted value of the constant term is @xmath194 . since in the @xmath192 interval we have 35 histogram bins , such background constant corresponds to @xmath195 combinatorial background events , that is about @xmath196 . the same conclusion follows also for cut ii . for the 560 experimental events which passed cut i , the following background constant was obtained : @xmath197 , which correspond to @xmath198 background events . subtracting the expected combinatorial background of @xmath199 , we can estimate the residual background from ( [ phietg ] ) , ( [ phikk ] ) , ( [ phif0 g ] ) , as @xmath200 events ( @xmath201 ) . for cut ii this background was found to be twice higher , that is @xmath202 background events from the selected 864 experimental events ( @xmath203 ) . on the other hand , monte carlo studies indicate the following probabilities for events from the main background sources to pass cut i : @xmath204 for process ( [ phietg ] ) , and @xmath205 for process ( [ phif0 g ] ) . this corresponds to @xmath206 background events from process ( [ phietg ] ) and @xmath207 from process ( [ phif0 g ] ) . so the total number of background events from these sources is estimated to be @xmath208 . for cut ii we expect @xmath209 and @xmath210 background events , respectively , or in total @xmath211 events . these numbers are in a good agreement with those obtained from the above mentioned fitting of the @xmath81-meson peak . to check the accuracy of monte carlo simulation the following procedure was applied . for the above described cut i and cut ii , one of the parameters is released and the resulting experimental distribution @xmath212 for this parameter is compared with the sum of mc predictions for the signal @xmath213 and expected backgrounds from ( [ phietg ] ) and ( [ phif0 g ] ) sources : @xmath214 . the normalization coefficients @xmath215 and @xmath216 are determined by the total statistics of generated mc samples for this reactions . the normalization coefficient for the signal @xmath217 is then determined from the condition that @xmath212 and @xmath218 histograms have the equal total numbers of events . note that any variation in the @xmath219 coefficient indicates some systematics and/or other background sources , not accounted for in the comparison . for cut i the averaged deviation turned out to be 3% and for cut ii the distributions for all parameters used in event selections show good agreement between @xmath220 and experiment . this indirectly indicates that the possible background from process ( [ phikk ] ) is rather small and does not exceed @xmath221 . as an example , on fig.[fig6 ] we present @xmath190 distributions . we assume the following parameterization for the visible ( detection ) cross section @xmath222 : @xmath223\sigma(s)+kb\sigma_b(s ) \ ; , \label{csvis } \end{aligned}\ ] ] where @xmath224 is the detection efficiency for the process ( [ eewpi ] ) , @xmath225 accounts for the radiative corrections , which are calculated according to the standard procedure @xcite , @xmath226 is a background cross section , which was assumed to coincide with @xmath227 , @xmath26 is the background suppression factor , @xmath228 is described below . finally , @xmath229 is a cross section of the process under investigation . because we are interested in @xmath229 in a narrow energy interval , we have taken @xmath230|r|^2 , \ ; \ ; r=1-z\frac{m_\phi \gamma_\phi}{s - m_\phi^2+im_\phi\gamma_\phi}. \label{sgfit } \end{aligned}\ ] ] the detection efficiency @xmath224 was calculated using monte - carlo simulation in conditions of individual scans for various energies . detection efficiencies do not show any significant energy dependence . so we have taken an efficiency value averaged over scans and energies , @xmath231 ( only statistical error is indicated ) as a fair estimate for cut ii . for a tighter cut i some systematic errors could be expected . to estimate this systematics , we compared the numbers of rejected events for each parameter of cut i in the above described @xmath212 and @xmath218 distributions . the following correction factors ( @xmath232 ) were obtained : @xmath233 for @xmath169 , @xmath234 for @xmath179 , @xmath235 for @xmath181 , @xmath234 for @xmath188 and @xmath236 for @xmath190 . in total , the monte carlo simulation overestimates the detection efficiency @xmath237 times , if we assume that there are no correlations between the used selection parameters . with this correction factor taken into account , an average detection efficiency @xmath238 was obtained for cut i. the background suppression factor @xmath26 was also assumed to be energy independent . it was calculated using @xmath239 simulated events from the process ( [ phietg ] ) and equals @xmath240 for cut i and @xmath241 for cut ii . as we have seen above , for cut i a relatively large fraction of background is expected from process ( [ phif0 g ] ) . some small amount of @xmath242 decay related background ( [ phikk ] ) is also not excluded . to take into account these and other @xmath1-meson related backgrounds , the factor @xmath228 is introduced in ( [ csvis ] ) . it is assumed that the different energy dependencies of various background cross - sections is not relevant at the present level of statistical accuracy and so they all can be approximated by the @xmath243 behavior . the fit results are given in the table [ tb1 ] . .fitted parameters for the fit with the interference . 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the @xmath0 process was investigated in the snd experiment at the vepp-2 m collider . a narrow energy interval near the @xmath1-meson was scanned . the observed cross - section reveals , at the level of three standard deviation , the interference effect caused by @xmath2 decay . the cross - section parameters , as well as the real and imaginary parts of the @xmath1-meson related amplitude , were measured .

insects - t. infestans were captured from domiciliary ( -d ) and sylvatic ( -s ) areas of bolivia ( department of cochabamba , viente de octubre - s , department of potos , kirus - mayu - s and department of tarija , el palmar - d ) and from argentina ( salta province , la pista - d ) in 2009 . table isylvatic ( -s ) and domiciliary ( -d ) populations of triatoma infestans analysed according to the collecting site in bolivia and argentinasite of collectionlocation ( locality / country)latitude / longitudekirus - mayu - storo toro / potos / bolivia1759 s 6550wveinte de octubre - scochabamba / cochabamba / bolivia1729 s 6607wel palmar - del palmar / tarija / bolivia1702 s 6412wla pista - dsalvador mazza / salta / argentina224 s 6341wnfssusceptible reference strain / argentina- sylvatic t. infestans were captured from rock piles using mouse - baited sticky traps ( noireau et al . eggs from the descendent populations were transported to the research center and insect pests ( cipein ) , buenos aires , argentina , where subsequent generations were bred . a susceptible reference strain ( nfs ) was derived from a domestic population captured in 2004 from santiago del estero , argentina , in an area where insects were later successfully controlled with the pyrethroid insecticide deltamethrin . the insects from each population were reared in boxes at 28c , 50 - 60% relative humidity ( rh ) and a photoperiod of 12:12 ( l : d ) h. one pigeon was provided each week to meet insect blood requirements ( who 1994 ) . chemicals - technical grade deltamethrin ( 99% ) was purchased from ehrestorfer ( augsburg , germany ) . analytical grade acetone was purchased from jt baker ( estado de mexico , mexico ) . 7-hydroxycoumarin ( 7-ohc ) ( umbelliferone ) was purchased from sigma - aldrich co ( st . louis , mo , usa ) . permethrinic acid [ ( 1r , s)- cis- ( 98.7% cis , 0.9% trans ) ] was supplied by chemotecnica ( buenos aires , argentina ) and the thionyl chloride ( cl 2 so , 99% ) and triethylamine ( 99% ) were purchased from aldrich chemical ( milwaukee , wi , usa ) . 7-coumaryl permethrate ( 7-cp ) was synthesised in the cipein using the method of santo - orihuela et al . topical application bioassays - twelve - day - old second generation ( f2 ) eggs were collected from adult rearing boxes and selected according to external morphological characteristics ( orange coloured eggs and dark eye spots ) as described by de villar et al . groups of at least 10 eggs per concentration were fixed to a microscope slide with double - sided adhesive tape . egg treatments were conducted individually using topical applications to the operculum of 0.2 l of serial deltamethrin dilutions in acetone using a 10 l hamilton syringe according to the method reported by picollo et al . final concentrations ranged from 0.0005 - 1 mg / ml deltamethrin diluted in acetone . at least four different concentrations producing between 10 - 90% mortality were used for each test . each concentration , including the acetone only control ( without insecticide ) , was replicated three times . following the topical application , eggs were incubated in a rearing cabinet ( foc-225e , velp scientifica , milan , italy ) at 28c , 50% rh and a photoperiod of 12:12 ( l : d ) h. the estimated time for hatching control eggs under these laboratory conditions was 15 days . mortality data were recorded six days after the topical application ( 3 days after the control eggs hatched ) . esterase activity - pyrethroid esterase activity was determined by measuring the hydrolysis of 7-cp , a fluorescent substrate used to determine pyrethroid hydrolysis activity in individual insects ( santo - orihuela et al . eggs were collected and selected using the same criteria as those used in the bioassays . the eggs were cooled and each egg was homogenised in 220 l of phosphate buffer ( 0.05 m , ph 7.2 ) using a plastic mortar and pestle . because the 7-cp pyrethroid esterase method was conducted with the entire volume of each individual insect homogenate , these tests could not be replicated . the reaction was initiated by adding 10 l of 7-cp ( in 3.5 mm 2-methoxyethanol ) to 190 l of each homogenate . the fluorescence was measured in a fluoroskan ascent microplate fluorometer ( thermo scientific , helsinki , finland ) and the results were analysed with ascent ( thermo scientific ) and microsoft excel 2010 ( microsoft ) . assays were conducted in black 96-well polystyrene flat - bottomed microtitre plates ( perkin elmer life and analytical sciences ) at 25c . 7-ohc production was monitored at an excitation wavelength of 390 nm and an emission wavelength of 440 nm ; 7-cp pyrethroid esterase activity was measured 3 min for 33 min . the relative fluorescence units ( rfu ) were corrected for background hydrolysis and nonspecific substrate fluorescence and then transformed to picomoles / min ( activity units ) using one calibration curve per replicate with dilutions of 7-ohc ( 68.5 , 342.69 , 685.44 and 1370.8 total picomoles / well ) . insect protein concentrations were quantified with a protein kit ( total protein kit , sigma ) based on the bradford ( 1976 ) assay . the absorbance of the wells was determined using a spectrophotometric microplate reader equipped with 340 nm , 405 nm , 415 nm , 540 nm , 595 nm and 655 nm wavelength filters ( model 680 , bio - rad laboratories , inc ) . microplate manager software v. 5.2.1 ( bio - rad laboratories , inc ) was used to collect , analyse and output absorbance data from the bio - rad microplate readers . statistical analysis - mortality data were processed with polo plus ( leora software 1987 ) . data from each t. infestans population were corrected using abbott s formula ( abbott 1987 ) and were then pooled and analysed based on probit analysis ( litchfield jr & wilcoxon 1949 ) to estimate the lethal dose ( ld ) ( nanograms of insecticide per egg ) that killed 50% of treated individuals ld ratios ( ldrs ) and 95% confidence intervals ( ci ) for each population were calculated according to robertson et al . ( 2007 ) by comparing the dose - response curves between studied populations and the reference strain nfs . studied populations were considered different from the reference strain according to the criteria of robertson et al . according to these criteria , the ldr 95% ci did not include the number 1.0 . the pyrethroid esterase activity values of eggs from different populations were expressed as picomoles of 7-ohc pmol / min / mg protein and these values were plotted on a scatter graph ( montella et al . statistical analysis was performed using instat v. 3.01 ( graphpad software , san diego , ca , usa ) . an anova test was used to compare protein amounts among study populations and non - parametric kruskal - wallis and dunn tests were used to compare 7-cp enzymatic activities per minute and per mg of protein among populations . figure and table ii show the toxicity of deltamethrin against 12-day - old t. infestans eggs from bolivia and argentina . the bolivian population el palmar - d showed the highest ld 50 and ldr values ( 27.80 ng / egg and 44.90 , respectively ) , whereas veinte de octubre - s had the lowest values ( 0.31 ng / egg and 0.50 , respectively ) . table iitoxicity of deltamethrin against triatoma infestans 12-days - old eggs from bolivia and argentinapopulationnslope se2dfld 50 ( ng per egg ) ( 95% ci)ldr ( 95% ci)kirus - mayu - s1071.79 0.481.6221.90 ( 1.25 - 3.36)3.02 ( 1.76 - 5.21)veinte de octubre - s740.92 0.291.6120.31 ( 0.06 - 0.94)0.50 ( 0.15 - 1.60)el palmar - d881.84 0.450.95227.80 ( 16.00 - 44.80)44.90 ( 25.60 - 77.20)la pista - d800.76 0.202.5646.80 ( 2.69 - 24.00)8.10 ( 1.02 - 26.37)nfs882.07 0.351.2620.61 ( 0.43 - 0.91)-ci : confidence interval [ calculated following robertson et al . ( 2007 ) ] ; -d : domestic population ; df : degrees of freedom ; ld : lethal dose ; ldr : ld ratios ; -s : sylvatic population ; se : standard error ; 2 : chi - square . 2 for probit analysis tests goodness - of - fit , in this case the values ( responses ) predicted by the statistical model adequately fit the data observed in the bioassay ( p > 0.05 ) . ( 2007 ) ] ; -d : domestic population ; df : degrees of freedom ; ld : lethal dose ; ldr : ld ratios ; -s : sylvatic population ; se : standard error ; 2 : chi - square . 2 for probit analysis tests goodness - of - fit , in this case the values ( responses ) predicted by the statistical model adequately fit the data observed in the bioassay ( p > 0.05 ) . the egg protein content results and statistical analyses from the study populations are shown in table iii . the sylvatic populations , kirus - mayu - s and veinte de octubre - s , had higher protein contents than the domestic populations , el palmar - d and la pista - d and the reference strain ( nfs ) . for this reason , all 7-cp activity values were corrected according to the mean protein content of the respective population and expressed per mg of protein . table iiimeans and standard deviations ( sd ) of protein content and activities of 7-coumaryl permethrate ( 7-cp ) esterasesstrain / populationn mean protein content sd ( g per insect)n 7-cp activity sd ( pmol / min / mg protein)kirus - mayu - s26400.82 ( 197.86 ) 2227.49 ( 9.83 ) veinte de octubre - s43350.83 ( 131.85 ) 4322.69 ( 9.41 ) el palmar - d26289.91 ( 156.75 ) 2840.11 ( 10.74 ) la pista - d35223.22 ( 96.16 ) 3536.64 ( 14.93 ) nfs24265.26 ( 118.42 ) 3234.92 ( 13.67 ) a : number of eggs used from studied populations in protein assay ; b : number of eggs used from studied populations in 7-cp activity determination . means of protein content followed by different letters ( c - e ) are significantly different ( p < 0.05 ) . values of activities of 7-cp esterases followed by different letters ( c - e ) are significantly different ( p < 0.05 ) [ kruskal wallis ( kw ) and dunn s multiple comparisons test ] . kw statistic = 42.45 . sd : standard deviation . a : number of eggs used from studied populations in protein assay ; b : number of eggs used from studied populations in 7-cp activity determination . means of protein content followed by different letters ( c - e ) are significantly different ( p < 0.05 ) . . values of activities of 7-cp esterases followed by different letters ( c - e ) are significantly different ( p < 0.05 ) [ kruskal wallis ( kw ) and dunn s multiple comparisons test ] . the domestic populations el palmar - d and la pista - d from bolivia and argentina , respectively , had 7-cp activity values ( 40.11 and 36.64 pmol / min / mg protein , respectively ) similar to the values for reference strain nfs ( 34.92 pmol / min / mg protein ) and were significantly different from the sylvatic populations kirus - mayu - s and veinte de octubre - s ( 27.49 and 22.69 pmol / min / mg protein , respectively ) . these data are shown with their standard deviations and statistical analyses in table iii . this study was the first analysis of pyrethroid esterase activities in eggs from sylvatic t. infestans using a specific substrate , namely , 7-cp ( santo - orihuela et al . previous studies have demonstrated the importance of sylvatic t. infestans and its possible role in recolonising insecticide - treated houses ( noireau 2009 , waleckx et al . most insecticides used in control campaigns are directed at larval and adult stages , but eggs are also subject to selection pressure . therefore , it is relevant to evaluate the susceptibility of sylvatic t. infestans eggs . in a previous study , roca - acevedo et al . ( 2011 ) analysed the toxicological profile of sylvatic t. infestans and found a slight increase in the ld 50 and ldr for deltamethrin in the first instars of sylvatic populations in contrast with the reference strain , but no statistical evidence of a detoxifying enzyme contribution was reported . in the present study , the eggs from domestic populations showed higher ldrs than the reference strain , indicating the development of embryonic resistance in these bolivian and argentine populations . these toxicological findings for eggs were in accordance with instar results demonstrated by germano et al . these data indicate that eggs from domestic populations were resistant to deltamethrin , but no statistical contribution from 7-cp esterases was observed . however , deltamethrin resistance may be attributed to a reduced nerve sensitivity caused by a change in the action site ( i.e. , kdr and sodium channels ) ( soderlund & knipple 2003 , fabro et al . the studied sylvatic populations showed ld 50 and ldr values similar to the reference strain , but with higher protein contents and lower pyrethroid esterase activities ; the increased protein content may be caused by differences in food sources and hosts under sylvatic conditions ( noireau et al . the toxicological pattern of sylvatic eggs in this study was very similar to the pattern of sylvatic instars described by roca - acevedo et al . the eggs in the present study had decreased 7-cp esterase activity in contrast with the reference strain and domestic population and a lower ldr than instars from previous studies ( roca - acevedo et al . ( 2008 ) demonstrated the existence of deltamethrin - susceptible eggs and resistant first instar nymphs in domestic t. infestans populations from sucre and mataral ( bolivia ) . these authors attributed this phenomenon to an insecticide selection response to different field insecticide exposures and/or biological variations between bolivian and argentinean populations . conversely , these sylvatic population findings might be explained by probable contact between sylvatic and domestic populations in neighbouring areas ( depickre et al . one of the sylvatic populations studied in this work ( kirus - mayu - s ) showed a slight increase in ldr , suggesting a lower susceptibility to deltamethrin . this finding may be explained by the existence of naturally decreased susceptibility by the development of resistance resulting from exposure to insecticides used in crops and vector control campaigns or by contact and probable gene flow between geographically close sylvatic and domestic resistant populations . additionally , a combination of these hypotheses may be possible ( lardeux et al . 2010 , depickre et al . 2012 , santo - orihuela et al . 2013 ) . based on the identification of different toxicological profiles according to different geographic areas for sylvatic and domestic t. infestans ( roca - acevedo et al . 2012 ) , it is possible to geographically define wild or domestic toxicological profiles . although previous studies have suggested that the andean valley in bolivia represents the centre of origin and dispersal for t. infestans ( bargues et al . if this profile existed , it would be located in completely sylvatic areas , far from human activities . to date , the studied sylvatic populations have not been situated far from human influence and these populations may be under insecticide pressure or in contact with domestic t. infestans during their life cycle . although nonspecific esterases and pyrethroid esterases are likely to play a physiological role during the embryonic development of t. infestans , no studies have analysed this topic . moreover , few reports have determined the occurrence of cholinesterases during egg neurogenesis in t. infestans and triatoma patagonica ( de villar et al . ( 1984 ) analysed the effects of parathion on cholinesterases and eserine - resistant esterases and the influence of parathion , malathion and fenitrothion on carboxylesterases in the developing embryo of t. infestans , respectively . for this reason , 7-cp activity comparisons among studied populations and the reference strain were conducted on the same day of embryonic development ( 12-day - old eggs ) . further studies in t. infestans eggs and nymphs should be performed to clarify the relevance of these geographically different wild and domestic toxicological and biochemical profiles in the development of resistance to pyrethroid and non - pyrethroid insecticides . these data might help to improve the effectiveness of chemical controls when applied directly to eggs , nymphs and adults .

the aim of the present work was to study the deltamethrin susceptibility of eggs from triatoma infestans populations and the contribution of pyrethroid esterases to deltamethrin degradation . insects were collected from sylvatic areas , including veinte de octubre and kirus - mayu ( bolivia ) and from domiciliary areas , including el palmar ( bolivia ) and la pista ( argentina ) . deltamethrin susceptibility was determined by dose - response bioassays . serial dilutions of deltamethrin ( 0.0005 - 1 mg / ml ) were topically applied to 12-day - old eggs . samples from el palmar had the highest lethal dose ratio ( ldr ) value ( 44.90 ) compared to the susceptible reference strain ( nfs ) , whereas the veinte de octubre samples had the lowest value ( 0.50 ) . pyrethroid esterases were evaluated using 7-coumaryl permethrate ( 7-cp ) on individually homogenised eggs from each population and from nfs . the el palmar and la pista samples contained 40.11 and 36.64 pmol / min / mg protein , respectively , and these values were statistically similar to nfs ( 34.92 pmol / min / mg protein ) and different from kirus - mayu and veinte de octubre ( 27.49 and 22.69 pmol / min / mg protein , respectively ) . the toxicological data indicate that the domestic populations were resistant to deltamethrin , but no statistical contribution of 7-cp esterases was observed . the sylvatic populations had similar ldr values to nfs , but lower 7-cp esterase activities . moreover , this is the first study of the pyrethroid esterases on t. infestans eggs employing a specific substrate ( 7-cp ) .

Eastern Libya is also being buffeted by strong crosscurrents that intelligence operatives are trying to monitor closely. The killing of Mr. Stevens has ignited public anger against the militias, underscored on Friday when thousands of Libyans took to the streets of Benghazi to demand that the groups be disarmed. The makeup of militias varies widely; some are moderate, while others are ultraconservative Islamists known as Salafis. Advertisement Continue reading the main story “The region’s deeply entrenched Salafi community is undergoing significant upheaval, with debate raging between a current that is amenable to political integration and a more militant strand that opposes democracy,” Frederic Wehrey, a senior policy analyst with the Carnegie Endowment for International Peace who closely follows Libya and visited there recently, wrote in a paper this month, “The Struggle for Security in Eastern Libya.” American intelligence operatives also assisted State Department contractors and Libyan officials in tracking shoulder-fired missiles taken from the former arsenals of the former Libyan Col. Muammar el-Qaddafi’s forces; they aided in efforts to secure Libya’s chemical weapons stockpiles; and they helped train Libya’s new intelligence service, officials said. Senior American officials acknowledged the intelligence setback, but insisted that information was still being collected using a variety of informants on the ground, systems that intercept electronic communications like cellphone conversations and satellite imagery. “The U.S. isn’t close to being blind in Benghazi and eastern Libya,” said an American official. Advertisement Continue reading the main story Spokesmen for the C.I.A., the State Department and the White House declined to comment on the matter on Sunday. Advertisement Continue reading the main story Within months of the start of Libyan revolution in February 2011, the C.I.A. began building a meaningful but covert presence in Benghazi, a locus of the rebel efforts to oust the government of Colonel Qaddafi. Advertisement Continue reading the main story Though the agency has been cooperating with the new post-Qaddafi Libyan intelligence service, the size of the C.I.A.’s presence in Benghazi apparently surprised some Libyan leaders. The deputy prime minister, Mustafa Abushagour, was quoted in The Wall Street Journal last week saying that he learned about some of the delicate American operations in Benghazi only after the attack on the mission, in large part because a surprisingly large number of Americans showed up at the Benghazi airport to be evacuated. Photo “We have no problem with intelligence sharing or gathering, but our sovereignty is also key,” said Mr. Abushagour. The attack has raised questions about the adequacy of security preparations at the two American compounds in Benghazi: the American mission, the main diplomatic facility where Mr. Stevens and another American diplomat died of smoke inhalation after an initial attack, and an annex a half-mile away that encompassed four buildings inside a low-walled compound. Advertisement Continue reading the main story From among these buildings, the C.I.A. personnel carried out their secret missions. The New York Times agreed to withhold locations and details of these operations at the request of Obama administration officials, who said that disclosing such information could jeopardize future sensitive government activities and put at risk American personnel working in dangerous settings. Newsletter Sign Up Continue reading the main story Please verify you're not a robot by clicking the box. Invalid email address. Please re-enter. You must select a newsletter to subscribe to. Sign Up Receive occasional updates and special offers for The New York Times's products and services. Thank you for subscribing. An error has occurred. Please try again later. View all New York Times newsletters. In Benghazi, both compounds were temporary homes in a volatile city teeming with militants, and they were never intended to become permanent diplomatic missions with appropriate security features built into them. Advertisement Continue reading the main story Neither was heavily guarded, and the annex was never intended to be a “safe house,” as initial accounts suggested. Two of the mission’s guards — Tyrone S. Woods and Glen A. Doherty, former members of the Navy SEALs — were killed just outside the villa’s front gate. A mortar round struck the roof of the building where the Americans had scrambled for cover. Secretary of State Hillary Rodham Clinton announced last week the creation of a review board to examine the attacks. The board is to be led by a veteran diplomat and former undersecretary of state, Thomas R. Pickering. Advertisement Continue reading the main story The F.B.I. has sent investigators — many from its New York field office — to Benghazi, but they have been hampered by the city’s tenuous security environment and the fact that they arrived more than a day after the attack occurred, according to senior American officials. Complicating the investigation, the officials said, is that many of the Americans who were evacuated from Benghazi after the attack are now scattered across Europe and the United States. It is also unclear, one of the officials said, whether there was much forensic evidence that could be extracted from the scene of the attacks. Advertisement Continue reading the main story Investigators and intelligence officials are now focusing on the possibility that the attackers were members of Al Qaeda in the Islamic Maghreb, or at least were in communication with the group during the four hours that elapsed between the initial attack at the mission and the second one at the mission’s annex. Representative Mike Rogers, a Michigan Republican who heads the House Intelligence Committee, said on CNN’s “State of the Union” program on Sunday that there was “a high degree of probability that it is an Al Qaeda or Al Qaeda-affiliated group that had a very specific target in mind, and that was to attack the consulate and cause as much harm, chaos and death as possible.” Foreign diplomats say that under security circumstances like those now in Libya, it is generally standard procedure to have a “safe house” in the vicinity of a main diplomatic facility that can be easily defended and evacuated. Advertisement Continue reading the main story “Normally, you try to keep the location of such a safe house secret, but in Benghazi right now, I think this was next to impossible,” Col. Wolfgang Pusztai, who until early August was Austria’s defense attaché to Libya and visited the country every month, wrote in an e-mail. “There are not too many foreigners hanging around, and it is quite easy to track them.” ||||| The Libyan authorities have given armed groups two days to vacate military bases and compounds as they seek to capitalise on the wave of people power that drove an Islamist militia from Benghazi at the weekend. Jihadist militias in Derna, Libya's Islamist stronghold, threw in the towel on Sunday, withdrawing from their stronghold and announcing they were disbanding to avoid a repeat of the scenes in Benghazi in which angry crowds sent armed gunmen fleeing. One of the routed militias was blamed for an attack on the US consulate two weeks ago that left four Americans dead including the ambassador, Chris Stevens. The de facto head of state, Muhammad Magariaf, president of Libya's parliament, met Benghazi politicians and security officials, anxious to fill a security vacuum that has emerged from the weekend violence, in which at least 11 people died. "The army chief Yussef al-Mangoush and Muhammad Magariaf have ordered all illegitimate militias should be removed from compounds and hand over their weapons to the national army," said Adel Othman al-Barasi, a spokesman for the defence ministry, according to Reuters. "A committee made up by the military police has been formed to take over the compounds and the weapons and hand these over to the army." Benghazi's army garrison commander, General Hamad Belkhair, said he was moving military police units into vacated militia bases. "What happened was a big mess," he said of the takeover by protesters of Benghazi's three militia bases on Friday night and Saturday morning. "But it has left the government clearly in control of the streets." Bilal Bettamer, a 22-year-old law student in the city who was one of the organisers of the Benghazi protests, said he was optimistic the militias would be disbanded. "You can't have 100% success in these situations. [But] that's what we wanted – the militias are put on notice and everyone knows now that this country will refuse any extremists and will eventually get rid of them, and become a country that we wanted on 17 February." He condemned the apparent killing of militia guards as a "stupid move" and speculated that pro-Gaddafi elements could be to blame. He even praised the courage of the militias for disbanding, claiming it showed they respected democracy. "Militias are not evil people, they are good people and they have saved Libya before. But it is time for legitimacy to take its place for the police and army. You can't build a country based on militias. "The army are back on the streets. You can see the army and police at night. The collection of individual weapons is beginning right now. They are doing their expected job. They have put small militia on notice to evacuate the neighbourhood. The army got braver. Everyone is telling them, strike with an iron fist." Yet extremists remain a presence: Belkhair himself was kidnapped on Saturday morning by masked gunmen and held for six hours before being released unharmed. He said he thought the group, who did not identify themselves, wanted him to limit the army's role in securing the city. Belkhair and police commanders are uneasily aware that the surge of people power that has swept militias from the streets could degenerate into anarchy, and that he lacks the manpower to impose order. An army unit from Sirte, former stronghold of the late dictator, Muammar Gaddafi, has occupied the compound of the Raffala al-Sahati militia, whose soldiers shot many of the 11 killed in the early hours of Saturday. Investigators are trying to establish who killed six militiamen whose bodies were found, each with a bullet to the head, in a field near the Raffala base. In Derna, a centre for Islamist resistance against the Gaddafi regime, two powerful jihadist formations, Abu Salem and Ansar al-Sharia, have agreed to disband. Commanders of both formations – the latter linked to the group blamed for the killing of Stevens – told Libya's state news agency that they had decided their role was over. In Tripoli, many foreign embassies remain in security lockdown, fearing jihadist units in the capital will seek revenge for the humiliating rout of their comrades in eastern Libya. Benghazi officials say the way is now clear for Washington to deploy an FBI team that is kicking its heels in Tripoli to join the investigation into the death of Stevens, who died from smoke inhalation after the attack on the consulate compound.

– Libya is working to drive out more armed groups after protesters' success against a militia blamed in the death of US ambassador Chris Stevens. Authorities have told "all illegitimate militias" they've got two days to "be removed from compounds and hand over their weapons to the national army," says a defense ministry spokesman. Over the weekend, protesters took over three militia bases; 11 people were killed in the process, the Guardian reports. "What happened was a big mess," says army commander General Hamad Belkhair. "But it has left the government clearly in control of the streets." Some militias are taking heed of the government's warnings, announcing they're calling it quits amid the backlash. Those groups include Ansar al-Sharia, blamed in Stevens' death. But others haven't given up; Belkhair was kidnapped for six hours on Saturday and finally released safely. Meanwhile, the attack on the US consulate earlier this month has created a roadblock for US intelligence efforts: Some dozen CIA agents and contractors were among those evacuated from Benghazi following the attack, the New York Times reports. "It’s a catastrophic intelligence loss," says a US official, even as the region grows more volatile. "We got our eyes poked out."

the wiedemann - franz ( wf ) law , which relates the thermal conductivity @xmath9 and the electrical conductivity @xmath10 through a simple formula , @xmath11 where @xmath12 is called the lorentz number and is given by the sommerfeld s value @xmath13 w@xmath14/k@xmath15 , is a robust signature of a fermi liquid . it relies on the single - particle description of the transport properties and a purely elastic electron scattering . although the wf law is usually not obeyed at @xmath16 0 because of the importance of inelastic scattering , it must be obeyed in the fermi liquid at @xmath17 0 where the electrons are elastically scattered by static disorders . the examination of the wf law at @xmath8 by using sub - kelvin charge and heat transport measurements can therefore provide a direct judgement on the nature of the normal state of high-@xmath18 cuprates , which is a prime example of the strongly - correlated electron systems challenging the description of fermi liquids . it has been found in the overdoped tl@xmath19ba@xmath19cuo@xmath20 ( tl2201 ) that the wf law is perfectly obeyed , which indicated a fermi - liquid ground state of the overdoped cuprates.@xcite it was recently predicted that the wf law is violated in disordered interacting electron systems,@xcite in which the coulomb interactions are likely to bring some additional scattering and impede the charge transport more efficiently . a recent study of the low-@xmath7 transport of bi@xmath21sr@xmath22cuo@xmath20 ( bi2201),@xcite in which a positive departure from the wf law ( @xmath23 ) appeared at optimum doping and became more pronounced in the underdoped regime , was argued to support the theoretical prediction because the disorder in bi2201 increases with decreasing doping level due to its peculiar chemistry . however , in previous studies , both on the overdoped tl2201 and on the underdoped bi2201 , the normal state was achieved by applying very strong magnetic field , which could induce some kind of sdw / cdw order.@xcite such a competing order may cause some uncertainty regarding whether the properties of the true ground state is indeed detected.@xcite it would therefore be useful if one could study the validity of the wf law in cuprates whose normal states is obtained in a way other than by applying a strong magnetic field . introducing impurities or defects into cuo@xmath19 planes is a viable way of suppressing the superconductivity and obtaining the normal state . because of the non-@xmath24-wave symmetry of cuprates , nonmagnetic impurities like zn or mg are found to destroy the superconductivity quite strongly , particularly for the underdoped cuprates.@xcite furthermore , the impurity substitution was found to show different impacts on the physical properties in the underdoped and the overdoped cuprates , signifying a remarkable difference in the corresponding ground states.@xcite it was found that in underdoped la@xmath22sr@xmath25cuo@xmath5 ( lsco ) and bi@xmath19sr@xmath22la@xmath25cuo@xmath20 ( bslco ) , a low-@xmath7 resistivity divergence shows up immediately after the superconductivity is completely suppressed by a slight zn substitution ( @xmath26 2%).@xcite the resistivity divergence is even stronger than the log(1/@xmath7 ) function , which is a well - known low-@xmath7 behavior of high - magnetic - field - induced insulating state,@xcite and therefore indicates an insulating ground state.@xcite the magnetoresistance data suggested that the zn - induced insulating state is likely due to kondo effect associated with impurity - induced magnetism.@xcite in any event , the normal state of these disordered and underdoped cuprates is apparently insulating and it is actually not meaningful to test the validity of the wf law for these samples . in optimally - doped or overdoped regimes , on the other hand , a slight zn substitution ( @xmath26 4% ) was found to induce a simply metallic state when the superconductivity is suppressed,@xcite which is believed to demonstrate the fermi liquid ground state of the overdoped cuprates . however , it was also found that the heavy electron irradiation ( to introduce point defects and to destroy the superconductivity similarly to zn substitution ) in the overdoped tl2201 can lead to a low-@xmath7 resistivity upturn,@xcite so the occurrence of electron localization in the overdoped regime appears to depend on the level of disorder . the temperature dependence of the conductivity suppression @xmath27 ( compared to the extrapolated residual conductivity from the high-@xmath7 data ) in the heavily - electron - irradiated tl2201 had a ln@xmath7 variation and was in rough quantitative agreement with the two - dimensional ( 2d ) weak localization theory . once the anderson transition into the insulating state takes place and the resistivity shows an exponentially divergent behavior due to strong disorder , even in the overdoped regime the wf law is meaningless . however , in the moderately disordered regime in which the superconductivity is suppressed by disorder but the resistivity is not really divergent , it becomes possible to examine the peculiar electron transport properties through the wf law without introducing the possible complications from the magnetic - field - induced effects . in this work , by substituting zn or mg for cu in la@xmath0sr@xmath1cu@xmath2@xmath3@xmath4o@xmath5 ( @xmath3 = zn or mg ) ( lscmo ) , we are able to obtain a series of non - superconducting overdoped lsco . when the superconductivity is just suppressed at zn concentration of @xmath6 = 0.049 and 0.082 , the ground state is clearly metallic and the wf law is found to hold reasonably well , pointing to the fermi - liquid state of the overdoped cuprates . with higher concentration of zn ( @xmath6 = 0.13 ) or mg ( @xmath6 = 0.15 ) , a low-@xmath7 resistivity upturn shows up . it is found that the @xmath7-dependence of the conductivity obeys a @xmath28 law and therefore indicates a metallic ground state at @xmath8 . this result , accompanied with the negative magnetoresistance , suggests a three - dimensional ( 3d ) weak localization behavior . however , the low-@xmath7 heat transport data indicate a surprisingly _ negative _ deviation from the wf law ( @xmath29 ) that is opposite to the theoretical prediction for the disordered interacting electron systems . this new result demonstrates yet another unconventional feature of the mysterious normal state of the high-@xmath18 cuprates . high - quality la@xmath0sr@xmath1cu@xmath2@xmath3@xmath4o@xmath5 ( @xmath3 = zn or mg ) single crystals are grown by a traveling - solvent floating - zone method with similar processes to that reported in ref . . the actual zn or mg concentration @xmath6 is determined by the inductively - coupled plasma atomic - emission spectroscopy ( icp - aes ) . all the samples are carefully checked by using the x - ray laue photograph and cut precisely along the crystallographic axes . the in - plane resistivity and the thermal conductivity are measured actually along the @xmath30 axis . to remove the oxygen defects which tend to occur in overdoped lsco , the crystals are annealed at 800@xmath31c in sealed quartz tubes with 4 atm oxygen pressure for at least 5 days , followed by rapid quenching to the liquid nitrogen temperature . several pieces of crystals used for transport measurements at each impurity concentration are labelled a " , b " , c " , etc . the in - plane resistivity @xmath32 is measured using a standard ac four - probe method in a @xmath33he cryostat from 1.4 to 300 k and using a lr-700 ac - resistance bridge in a dilution refrigerator from 80 to 900 mk , respectively . in the latter case , excitation voltages are minimized to avoid observable self - heating effect . the thermal conductivity measurement in the sub - kelvin region is done by a conventional steady - state one heater , two thermometer " technique with ruo@xmath19 sensors in the dilution refrigerator.@xcite 10% ) of the resistivity data between different samples at the same impurity concentration indicates a high quality of the crystals.,width=321 ] figure 1 shows the in - plane resistivity @xmath32 of several zn- and mg - substituted lsco single crystals with sr content @xmath34 = 0.2 . the pristine lsco sample shows a good @xmath7-linear behavior of @xmath32 below 300 k and a sharp superconducting transition at 34.5 k. with increasing zn concentration to @xmath6 = 0.049 and 0.082 , the linearity of the resistivity becomes a bit worse but obviously a metallic behavior ( with positive temperature coefficient ) persists down to very low temperature without displaying any superconducting transition . when zn concentration increases to 0.13 , the resistivity starts to show a weak upturn below @xmath26 12 k. in mg - substituted samples ( @xmath6 = 0.15 ) , the low - temperature upturn of the resistivity is pronounced . these data demonstrate the impact of impurity / disorder on the electron transport and superconductivity , all consistent with the literature.@xcite in particular , the low-@xmath7 resistivity upturn in the heavily zn- or mg - substituted samples are qualitatively the same as that in the electron irradiated tl2201.@xcite 0.13 ) and mg - substituted ( @xmath6 = 0.15 ) lsco single crystals in different magnetic fields ( 016 t and along the @xmath35 axis ) . ( c , d ) the electrical conductivity of the above two samples in 0 and 16 t fields , plotted in @xmath36 vs @xmath28 . the solid lines are linear fittings to the low - temperature data.,width=321 ] to further investigate the low-@xmath7 transport properties of highly zn- and mg - substituted lsco , the in - plane resistivity is studied down to milli - kelvin temperature and in magnetic fields from 0 to 16 t ( @xmath37 ) . the detailed data are shown in figs . 2(a ) and 2(b ) in log@xmath7 plots . first of all , the resistivity of these samples keeps increasing upon lowering temperature down to the lowest temperature ( @xmath26 80 mk ) . however , the increase in resistivity is apparently weaker than the log(1/@xmath7 ) function , which is a common insulating behavior in both the high - magnetic - field - induced normal state of underdoped high-@xmath18 cuprates and the lightly - doped non - superconducting yba@xmath19cu@xmath38o@xmath39 ( ybco).@xcite this observation suggests that the resistivity may not diverge in the zero - temperature limit in these samples . it is actually easy to find , as shown in figs . 2(c ) and 2(d ) , that the low-@xmath7 electrical conductivity of these samples follows a power law @xmath40 where @xmath41 and @xmath42 are temperature - independent coefficients . it follows from this temperature dependence that the resistivity @xmath43 remains finite at @xmath44 0 , which is a clear indication of a metallic ground state of these samples . note that this @xmath7-dependence of resistivity is somehow different from the ln@xmath7 variation of @xmath27 observed in the overdoped tl2201 after significant electron irradiation.@xcite since the measurements of tl2201 were not done at very low temperatures , a direct comparison between lscmo and tl2201 is not available now . nevertheless , the 2d weak localization picture proposed for tl2201 , which is based on the ln@xmath7 behavior of conductivity , may not be appropriate for lscmo . remember , the particular @xmath28 dependence of conductivity is known for the 3d weak localization.@xcite it is possible that the overdoped lsco with strong disorder is effectively a 3d electron system , though the temperature dependence of the resistivity anisotropy suggests that clean lsco is two dimensional for the whole superconducting compositions ( @xmath45 0.30).@xcite another important feature one may note in fig . 2 is that the low-@xmath7 resistivity decreases in magnetic fields , that is , they show rather strong negative magnetoresistance . this immediately rules out the possible contamination of the superconducting fluctuations to the resistivity data and suggests that the weak negative temperature coefficient of resistivity is due to the intrinsic electron transport of the normal state . furthermore , the negative magnetoresistance at low temperature also indicates that the weak localization is likely responsible for the resistivity upturn.@xcite as a summary of the electrical transport results , the resistivity upturn in the heavily zn- and mg - substituted and carrier - overdoped lsco does not signify a metal - to - insulator crossover ( mic ) but is attributed to an inelastic electron scattering by impurities / disorders in a metallic regime . furthermore , the temperature dependence of the low-@xmath7 resistivity does not suggest a kondo - like scattering mechanism , which is often playing a role in the charge transport in underdoped cuprates.@xcite vs @xmath46 and ( b ) @xmath47 vs @xmath7 . the solid lines are linear fittings to the low - temperature data in two different plots . note the difference in the residual term obtained by the two kinds of analysis . the solid symbols at @xmath7 = 0 k indicate the values of @xmath47 calculated by using the wiedemann - franz law with the residual resistivity obtained from fig . 1 . note that the calculated @xmath48 and the experimental @xmath47 data are shown with the same shape of the symbols for the same samples.,width=245 ] to further investigate the electron transport properties , the thermal conductivity @xmath9 of zn- and mg - substituted lsco samples shown in fig . 1 have been measured down to 70 mk ; fig . 3 shows the data for the superconducting la@xmath0sr@xmath1cuo@xmath5 sample and lscmo samples with zn concentration of 0.049 and 0.082 , which showed the metallic resistivity behavior down to very low temperatures . note that the low-@xmath7 thermal conductivity of all these samples can be well fitted either to @xmath49 or to @xmath50 as shown in figs . 3(a ) and 3(b ) , respectively , but the temperature range for obtaining a good fit is much wider with using eq . ( [ t ] ) . looking at fig . 3 , one may notice that the data quality of these charge - carrier - overdoped lsco samples are unprecedentedly high . in a previous study,@xcite some clear downturn of the low-@xmath7 thermal conductivity data was observed in the overdoped lsco and was already discussed to be due to the electron - phonon decoupling,@xcite whose adverse effects on probing the intrinsic electron thermal conductivity can be avoided if the contacts are good enough . note that eq . ( [ t^2 ] ) is commonly used for describing the low-@xmath7 thermal conductivity of superconducting cuprates , where the residual term @xmath48 is the contribution of @xmath51-wave nodal quasiparticles and @xmath52 is the phonon contribution in the boundary scattering limit.@xcite in this regard , the present data of the pristine lsco are in good harmony with the previous studies . for samples with zn concentrations of 0.049 and 0.082 , whose ground state is metallic as indicated by the in - plane resistivity , @xmath48 is apparently coming from the electron heat transport as in ordinary metals . if the ground state is a fermi liquid , one can expect that the values of the residual resistivity and @xmath48 satisfy the wf law . from fig . 3(a ) , it is clear that there is about 20% difference between the @xmath48 obtained from eq . ( [ t^2 ] ) and the values calculated from the residual resistivity ( see fig . 1 ) using the wf law . note that this 20% difference is not mainly due to the experimental error , since the resistivity and thermal conductivity measurements are performed using the same samples and the same contacts . it was recently reported that eq . ( [ t ] ) is a good description for the low-@xmath7 thermal conductivity of tl2201 and bi@xmath19sr@xmath19cacu@xmath19o@xmath53.@xcite as shown in fig . 3(b ) , fitting the present thermal conductivity data to eq . ( [ t ] ) gives qualitatively the same behavior upon zn substitution as that in fig . 3(a ) , but the @xmath48 from this fitting agree better ( in fact , almost perfectly ) with those from the wf law . this gives a circumstantial support to the validity of eq . ( 4 ) in the overdoped regime . compared to the underdoped lsco , in which a modified formula with the phonon boundary scattering @xmath54 ( @xmath55 = 2.53 ) was proposed to fit the data well,@xcite the second term @xmath56 in eq . ( [ t ] ) is apparently not originating from the boundary scattering limit . one possible explanation for this unusual power is the effect of strong electron - phonon scattering on phonons . it has been known that a @xmath46 behavior of the phonon thermal conductivity can show up in both usual metals and @xmath51-wave superconductors.@xcite in the case of a @xmath51-wave superconductor , the fermi surface is anisotropicaly gapped except for the gap nodes , nearby where the quasiparticles are excited even at low temperature.@xcite those so - called nodal quasiparticles dominate the transport properties.@xcite for such a system , it was theoretically proposed that the @xmath46 behavior of the phonon thermal conductivity originates from the fact that the transverse phonons propagating along certain high - symmetry directions do not interact with the nodal quasiparticles.@xcite however , the non - superconducting overdoped samples have a complete fermi surface , and therefore a very different momentum distribution of electrons from that in @xmath51-wave superconductors is formed . apparently , the electron - phonon scattering should differ significantly for the zn - free and zn - substituted samples , considering the distinct difference in the electronic structures between the superconducting and non - superconducting samples . therefore , the @xmath46 coefficient is expected to be quite different in these two cases . nevertheless , as shown in fig . 3 , the coefficient @xmath57 of the pristine ( superconducting ) and zn - substituted ( non - superconducting ) lsco are found to be nearly the same , which seems to rule out the possibility that the @xmath46-law comes from the electron - phonon scattering . in addition , one may notice that , when the electron - phonon scattering is strong , the electronic thermal conductivity @xmath58 can not be temperature independent and therefore eq . ( [ t ] ) is physically imprecise.@xcite another possible origin of the @xmath56 term is the phonon thermal conductivity with the dominant scattering of dislocations.@xcite this scenario is consistent with the observation that eq . ( [ t^2 ] ) becomes a good description of the data at very low temperatures , because the dislocation scattering is likely to be smeared out at low enough temperatures . there is a possibility that some dislocation defects are produced in lsco crystals when they are quenched to nitrogen temperature after high - temperature annealing . in any case , it appears that the wf law holds reasonably well ( the deviation is no more than 20% ) in the overdoped lsco when the normal state is obtained by a moderate impurity substitution . if one could take the validity of the wf law as a robust signature of a fermi - liquid state , the present result apparently indicates a fermi - liquid nature of the overdoped lsco . this conclusion is essentially the same as that for the overdoped tl2201 , where the normal state was achieved by strong magnetic fields.@xcite however , one should note that the resistivity of our moderately zn - substituted samples actually shows a good @xmath7-linear behavior at low temperature , which has been taken as a characteristic non - fermi - liquid feature.@xcite therefore , there is still some inconsistency between the interpretations of the wf law and the resistivity behavior in overdoped lsco , which needs further clarification . = 0.13 ) and mg - substituted ( @xmath6 = 0.15 ) lsco single crystals . ( a , b ) data are plotted in @xmath47 vs @xmath46 and the linear relationship is not observed even in the lowest temperature regime . ( c , d ) data are plotted in @xmath47 vs @xmath7 and @xmath47 vs @xmath59 for zn- and mg - substituted samples , respectively . linear fittings to the low - temperature data are shown by solid lines . the arrows indicate the residual thermal conductivity @xmath48 calculated by using the wiedemann - franz law from the residual electrical conductivity @xmath41 of the data shown in fig . 2 ; note that they are very different from the extrapolated residual value indicated by the linear fitting to the experimental data.,width=321 ] the low - temperature thermal conductivity data of lscmo with higher impurity concentration @xmath6 = 0.13 ( @xmath3 = zn ) and 0.15 ( @xmath3 = mg ) are shown in fig . 4 . from figs . 4(a ) and 4(b ) , it can be seen that the usual formula of eq . ( [ t^2 ] ) is not able to fit the low-@xmath7 thermal conductivity data , that is , the experimental data plotted in @xmath47 vs @xmath46 never show a linear behavior down to @xmath26 60 mk ; in fact , the curves always have a negative curvature . this phenomenon is very similar to what we observed in the lightly - doped non - superconducting ybco,@xcite in which case the heading of @xmath47 to zero upon lowering temperatures and the log(1/@xmath7)-divergent resistivity demonstrated the insulating ground state . in the present case , we would like to point out at the beginning that the curvature of @xmath47 vs @xmath46 plots is _ not _ likely due to the decoupling of electrons and phonons.@xcite it is known that the necessity of making good contacts to obtain the intrinsic electronic thermal conductivity data becomes more severe when the electron term becomes larger . comparing the data shown in figs . 4 and 3 , one can easily see that the pristine and lower zn - substituted lsco samples , which must have larger electron thermal conductivity than @xmath6 = 0.13 ( @xmath3 = zn ) and 0.15 ( @xmath3 = mg ) samples , actually do not show obvious sign of downturn curvature in their @xmath47 vs @xmath46 plots . upon further analyzing the data , one can find that eq . ( [ t ] ) is still able to fit the thermal conductivity data of @xmath6 = 0.13 ( @xmath3 = zn ) samples very well from 60 to 400 mk , as shown in fig . because of the even stronger curvature in the @xmath47 data of @xmath6 = 0.15 ( @xmath3 = mg ) sample , neither eq . ( [ t^2 ] ) nor eq . ( [ t ] ) can fit the data ; instead , the low-@xmath7 data of mg - substituted lsco can be described by a formula @xmath60 with the fitting parameter @xmath48 = 0 . as we have seen in sec . a. , the charge transport data indicate that in the heavily zn- or mg - substituted lsco some inelastic scattering is taking place at low temperatures , causing a weak localization behavior . one direct consequence of this fact is that @xmath58 is no longer independent of temperature in these samples , and the resistivity upturn naturally corresponds to a gradual decrease of @xmath58 with lowering temperatures . obviously , this invalidates eq . ( [ t ] ) . nevertheless , one can apparently fit the data for @xmath6 = 0.13 ( @xmath3 = zn ) samples to eq . ( [ t ] ) , which is probably due to the fact that the low-@xmath7 resistivity upturn ( @xmath61 10% increase in @xmath32 from 900 to 80 mk ) or the inelastic scattering are weak enough to make the deviations of @xmath58 from a constant effectively negligible . in contrast , the @xmath6 = 0.15 ( @xmath3 = mg ) samples show even stronger resistivity upturn and more significant inelastic scattering . it is likely that a considerable temperature dependence of the electronic term @xmath58 is the cause of eq . ( [ t^0.8 ] ) , which is an approximate description of the low-@xmath7 thermal conductivity of mg - substituted sample . based on the linear fittings ( shown in fig . 4 ) to obtain the residual term @xmath48 , one can easily find an important result , that is , the wf law in these metallic samples are strongly violated . as shown in figs . 4(c ) and 4(d ) , the @xmath48 values obtained from the extrapolation of the thermal conductivity data to @xmath7 = 0 k are much smaller than those predicted by the wf law using the residual conductivity shown in figs . 2(c ) and 2(d ) . especially , the mg - substituted lsco crystal gives a @xmath48 value that is essentially zero , indicating a thermal insulator " ground state , while the resistivity data suggest a finite residual term and a metallic ground state . it is surprising that the departure from the wf law is _ negative _ , which has never been observed in cuprates ; for example , upon approaching mic in the underdoped region of cuprates , the departure from the wf law was found to be positive . @xcite intriguingly , there is another metallic system which exhibits a negative deviation from the wf law : it is the heavy - fermion system cecoin@xmath62 when tuned to its quantum critical point ( qcp).@xcite in that materials , the violation of the wf law is accompanied by a @xmath7-linear resistivity and has been discussed to be due to an anisotropic destruction of the fermi surface . such a qcp - related origin of the wf - law violation is unlikely for lsco , given that the violation is _ not _ observed in less disordered ( @xmath6 = 0.049 and 0.082 ) samples . in passing , it is useful to note that the negative departure from the wf law is contrary to the theoretical predictions for the disordered interacting electron systems.@xcite although one could speculate that this unusual breakdown of the wf law in lsco may be related to the strong electron correlations or the antiferromagnetic spin fluctuations in cuprates , the validity of the wf law in samples with lower zn - concentrations does not support this speculation . hence , the charge and heat transport properties in the moderately disordered , weakly localized regime call for deeper theoretical investigations on systems in the vicinity of electron localization both the charge and heat transports properties are studied in overdoped lsco where the superconductivity is completely suppressed by zn- or mg - substitution . when the superconductivity is just destroyed with the zn substitution of @xmath6 = 0.049 and 0.082 , the ground state is clearly metallic and the wf law is found to hold reasonably well , pointing to the fermi - liquid nature of the overdoped cuprates . with higher doping of zn ( @xmath6 = 0.13 ) or mg ( @xmath6 = 0.15 ) , a low-@xmath7 resistivity upturn shows up but the @xmath7-dependence of the electrical conductivity follows a @xmath28 law and therefore indicates a metallic ground state . in this metallic state , which is in the regime of 3d weak localization , the low-@xmath7 transport data indicate a surprisingly negative deviation from the wf law that is opposite to the theoretical prediction for the disordered interacting electron systems . this work was supported by the national natural science foundation of china ( grant nos . 10774137 and 50721061 ) , the national basic research program of china ( grant nos . 2006cb922005 and 2009cb929502 ) , the research fund for the doctoral program of higher education of china ( grant no . 20070358076 ) , and kakenhi nos . 19674002 and 20030004 . b. lake , g. aeppli , k. n. clausen , d. f. mcmorrow , k. lefmann , n. e. hussey , n. mangkorntong , m. nohara , h. takagi , t. e. mason , and a. schroder , science * 291 * , 1759 ( 2001 ) ; b. lake , h. m. ronnow , n. b. christensen , g. appli , k. lefmann , d. f. mcmorrow , p. vorderwisch , p. smeibidl , n. mangkorntong , t. sasagawa , h. nohara , h. takagi , and t. e. mason , nature ( london ) * 415 * , 299 ( 2002 ) . j. e. sonier , f. d. callaghan , y. ando , r. f. kiefl , j. h. brewer , c. v. kaiser , v. pacradouni , s. a. sabok - sayr , x. f. sun , s. komiya , w. n. hardy , d. a. bonn , and r. liang , phys . b * 76 * , 064522 ( 2007 ) . d. g. hawthorn , r. w. hill , c. proust , f. ronning , m. sutherland , e. boaknin , c. lupien , m. a. tanatar , j. paglione , s. wakimoto , h. zhang , l. taillefer , t. kimura , m. nohara , h. takagi , and n. e. hussey , phys . lett . * 90 * , 197004 ( 2003 ) . d. g. hawthorn , s. y. li , m. sutherland , e. boaknin , r. w. hill , c. proust , f. ronning , m. a. tanatar , j. paglione , l. taillefer , d. peets , r. liang , d. a. bonn , w. n. hardy , and n. n. kolesnikov , phys . b * 75 * , 104518 ( 2007 ) .

to investigate the validity of the wiedemann - franz ( wf ) law in disordered but metallic cuprates , the low - temperature charge and heat transport properties are carefully studied for a series of impurity - substituted and carrier - overdoped la@xmath0sr@xmath1cu@xmath2@xmath3@xmath4o@xmath5 ( @xmath3 = zn or mg ) single crystals . with moderate impurity substitution concentrations of @xmath6 = 0.049 and 0.082 ( @xmath3 = zn ) , the resistivity shows a clear metallic behavior at low temperature and the wf law is confirmed to be valid . with increasing impurity concentration to @xmath6 = 0.13 ( @xmath3 = zn ) or 0.15 ( @xmath3 = mg ) , the resistivity shows a low-@xmath7 upturn but its temperature dependence indicates a finite conductivity in the @xmath8 limit . in this weakly - localized metallic state that is intentionally achieved in the overdoped regime , a _ negative _ departure from the wf law is found , which is opposite to the theoretical expectation .

SECTION 1. SHORT TITLE. This Act may be cited as the ``Congressional Commission on the Abolition of Modern-Day Slavery Act''. SEC. 2. MODERN-DAY SLAVERY. In this Act, the term ``modern-day slavery'' means the recruitment, harboring, transportation, receipt, procurement, or control of persons through the use of force, fraud, coercion, abduction, deception, abuse of power, or of a position of vulnerability or of the giving or receiving of payments or benefits to achieve the consent of a person having control over another person, for the purpose of subjection to debt bondage, serfdom, involuntary servitude, forced labor, chattel, forced marriage, peonage, sexual exploitation, or trafficking. SEC. 3. FINDINGS. Congress makes the following findings: (1) The Declaration of Independence recognizes the inherent dignity and worth of all people and states that all people are created equal and are endowed by their Creator with certain unalienable rights, and the right to be free from slavery and involuntary servitude is among those unalienable rights. (2) Despite international laws outlawing modern-day slavery, modern-day slavery affects virtually every country in the world, and as many as 27,000,000 people are victims. Modern-day slavery is one of the fastest growing areas of international criminal activity and is an increasing concern to the United States Administration, Congress, and the international community; the Federal Bureau of Investigation estimated that modern-day slavery generates over $9,000,000,000 every year. (3) Traffickers use threats, intimidation manipulation, coercion, fraud, shame, and violence to force victims into modern-day slavery. Traffickers capitalize on areas of conflict and post-conflict, transitioning states, sudden political change, economic collapse, civil unrest, internal armed conflict, chronic unemployment, widespread poverty, personal disaster, lack of economic opportunity, and natural disasters. (4) Modern-day slavery: contributes to the breakdown of societies due to the loss of family support networks; has a negative impact on the labor market in countries; brutalizes men, women, and children and exposes them to rape, torture, HIV/AIDS and other sexually transmitted diseases, violence, dangerous working conditions, poor nutrition, drug and alcohol addiction, severe psychological trauma from separation, coercion, sexual abuse, and depression; and strips human beings of dignity, respect, and hope for their future. (5) The United States has given priority to combating human trafficking through the Victims of Trafficking and Violence Protection Act of 2000 (Public Law 106-386) and the Trafficking Victims Protection Reauthorization Act of 2005 (Public Law 109- 164). (6) The State Department issued its sixth congressionally mandated Trafficking in Persons Report (TIP) in June, 2006, which categorizes countries into tiered groups according to the efforts they are making to combat trafficking. The countries that do not cooperate in the fight against trafficking (Tier 3 Countries) have been made subject to United States sanctions since 2003, under the President's direction. SEC. 4. ESTABLISHMENT OF COMMISSION. (a) Establishment.--There is established a congressional Commission on the Abolition of Modern-Day Slavery (referred to in this Act as the ``Commission''). (b) Membership.-- (1) Composition.--The Commission shall be composed of 12 members, of whom-- (A) 3 shall be appointed by the Speaker of the House of Representatives; (B) 3 shall be appointed by the majority leader of the Senate; (C) 3 shall be appointed by the minority leader of the House of Representatives; and (D) 3 shall be appointed by the minority leader of the Senate. (2) Qualifications.--Members of the Commission shall be appointed from among individuals with demonstrated expertise and experience in combating modern-day slavery and trafficking of persons. (3) Date.--The appointments of the members of the Commission shall be made not later than 30 days after the date of enactment of this Act. (c) Period of Appointment; Vacancies.--Members shall be appointed for the life of the Commission. Any vacancy in the Commission shall not affect its powers, but shall be filled in the same manner as the original appointment. (d) Cochairpersons.--The Speaker of the House of Representatives shall designate 1 of the members appointed under subsection (b)(1)(A) as a cochairperson of the Commission. The majority leader of the Senate shall designate 1 of the members appointed under subsection (b)(1)(B) as a cochairperson of the Commission. (e) Initial Meeting.--Not later than 60 days after the date of enactment of this Act, the Commission shall hold its first meeting. (f) Meetings.--The Commission shall meet at the call of either cochairperson. (g) Quorum.--A majority of the members of the Commission shall constitute a quorum, but a lesser number of members may hold hearings. SEC. 5. DUTIES OF THE COMMISSION. (a) Study.-- (1) In general.--The Commission shall-- (A) conduct a thorough and thoughtful study of all matters relating to modern-day slavery, including vulnerabilities of commonly affected populations, such as populations in areas of conflict and post conflict, transitioning states, states undergoing sudden political change, economic collapse, civil unrest, internal armed conflict, chronic unemployment, widespread poverty, lack of opportunity, and national disasters; (B) study the roles of the rule of law, lack of enforcement, and corruption within international law enforcement institutions that allow the proliferation of modern-day slavery; (C) review all relevant governmental programs in existence on the date of the beginning of the study, including the United States Agency for International Development, the Department of State, the Department of Defense, the Department of Labor, the Department of Health and Human Services, the Interagency Task Force to Monitor and Combat Trafficking, and the Human Smuggling and Trafficking Center; and (D) convene additional experts from relevant nongovernmental organizations as part of the Commission's thorough review. (2) Goals.--In making determinations under paragraph (1), the Commission shall seek to promote goals of-- (A) providing a comprehensive and fully integrated evaluation of best practices, to prevent modern-day slavery; (B) providing a comprehensive and fully integrated evaluation of the best practices to rescue and rehabilitate victims of modern-day slavery; (C) providing a comprehensive and fully integrated evaluation of the best practices for prosecution of traffickers and increasing accountability within countries; (D) providing a comprehensive and fully integrated evaluation of exportable models to prevent modern-day slavery, rescue and rehabilitate victims of modern-day slavery, prosecute offenders, and increase education and accountability about modern-day slavery, which could contribute governments, nongovernmental organizations, and institutions; (E) identifying countries which provide the greatest opportunity for abolition of modern-day slavery specific to United States involvement; (F) connecting various organizations to facilitate integration of information regarding identifying, extracting, and rehabilitating victims; (G) examining the economic impact on communities and countries that demonstrate measured success in fighting modern-day slavery; (H) increasing education and awareness about modern-day slavery throughout the United States to decrease modern-day slavery within the United States and abroad; and (I) providing a comprehensive evaluation of best practices to educate high-risk populations. (b) Recommendations.--The Commission shall develop recommendations on how to best combat modern-day slavery, including an economic, social, and judicial evaluation. (c) Report.--Not later than 11 months after the date of enactment of this Act, the Commission shall submit a report to the Speaker and minority leader of the House of Representatives and the majority leader and minority leader of the Senate, which shall contain a detailed statement of the legislation and administrative actions as it considers appropriate. SEC. 6. POWERS OF THE COMMISSION. (a) Hearings.--The Commission may hold such hearings, sit and act at such times and places, take such testimony, and receive such evidence as the Commission considers necessary to carry out this Act. (b) Information From Governmental Agencies.--The Commission may secure directly from any department or agency such information as the Commission considers necessary to carry out this Act. Upon request of either cochairperson of the Commission, the head of such department or agency shall furnish such information to the Commission. SEC. 7. COMMISSION PERSONNEL MATTERS. (a) Compensation of Members.--Each member of the Commission who is not an officer or employee of the Federal Government shall be compensated at a rate equal to the daily equivalent of the annual rate of basic pay prescribed for level IV of the Executive Schedule under section 5313 of title 5, United States Code, for each day (including travel time) during which such member is engaged in the performance of the duties of the Commission. All members of the Commission who are officers or employees of the United States shall serve without compensation in addition to that received for their services as officers or employees of the United States. (b) Travel Expenses.--The members of the Commission shall be allowed travel expenses, including per diem in lieu of subsistence, at rates authorized for employees of agencies under subchapter I of chapter 57 of title 5, United States Code, while away from their homes or regular places of business in the performance of services for the Commission. (c) Staff.-- (1) In general.--The cochairpersons of the Commission, acting jointly, may, without regard to the civil service laws and regulations, appoint and terminate an executive director and such other additional personnel as may be necessary to enable the Commission to perform its duties. The employment of an executive director shall be subject to confirmation by the Commission. (2) Compensation.--The cochairpersons of the Commission, acting jointly, may fix the compensation of the executive director and other personnel without regard to chapter 51 and subchapter III of chapter 53 of title 5, United Sates Code, relating to classification of positions and General Schedule pay rates, except that the rate of pay for the executive director and other personnel may not exceed the rate payable for level V of the Executive Schedule under section 5316 of such title. (d) Detail of Government Employees.--Federal Government employees may be detailed to the Commission without reimbursement, and such detail shall be without interruption or loss of civil service status or privilege. (e) Procurement of Temporary and Intermittent Services.--The cochairpersons of the Commission, acting jointly, may procure temporary and intermittent services under section 3109(b) of title 5, United States Code, at rates for individuals which do not exceed the daily equivalent of the annual rate of basic pay prescribed for level V of the Executive Schedule under section 5316 of such title. SEC. 8. TERMINATION OF THE COMMISSION. The Commission shall terminate 90 days after the date on which the Commission submits its report under section 5. SEC. 9. AUTHORIZATION OF APPROPRIATIONS. (a) In General.--There are authorized to be appropriated to the Commission for fiscal year 2007 such sums as may be necessary to carry out this Act. (b) Availability.--Any sums appropriated under the authorization contained in this section shall remain available, without fiscal year limitation, until expensed.

Congressional Commission on the Abolition of Modern-day Slavery Act - Defines "modern-day slavery." Establishes a congressional Commission on the Abolition of Modern-day Slavery which shall: (1) study matters relating to modern-day slavery, including vulnerabilities of commonly affected populations; (2) study the roles of the rule of law, lack of enforcement, and corruption within international law enforcement institutions that allow the proliferation of modern-day slavery; (3) review relevant governmental programs; and (4) convene additional experts from nongovernmental organizations as part of the Commission's review. States that the Commission shall seek to promote goals of: (1) providing a comprehensive evaluation of best practices to prevent modern-day slavery, to rescue and rehabilitate its victims, and to prosecute traffickers and increase accountability within countries; (2) identifying countries which provide the greatest opportunity for abolition of modern-day slavery specific to U.S. involvement; (3) examining the economic impact on communities and countries that demonstrate measured success in fighting modern-day slavery; and (4) increasing education and awareness about modern-day slavery.

SECTION 1. SHORT TITLE. (a) Short Title.--This Act may be cited as the ``Trademark Dilution Revision Act of 2006''. (b) References.--Any reference in this Act to the Trademark Act of 1946 shall be a reference to the Act entitled ``An Act to provide for the registration and protection of trademarks used in commerce, to carry out the provisions of certain international conventions, and for other purposes'', approved July 5, 1946 (15 U.S.C. 1051 et seq.). SEC. 2. DILUTION BY BLURRING; DILUTION BY TARNISHMENT. Section 43 of the Trademark Act of 1946 (15 U.S.C. 1125) is amended-- (1) by striking subsection (c) and inserting the following: ``(c) Dilution by Blurring; Dilution by Tarnishment.-- ``(1) Injunctive relief.--Subject to the principles of equity, the owner of a famous mark that is distinctive, inherently or through acquired distinctiveness, shall be entitled to an injunction against another person who, at any time after the owner's mark has become famous, commences use of a mark or trade name in commerce that is likely to cause dilution by blurring or dilution by tarnishment of the famous mark, regardless of the presence or absence of actual or likely confusion, of competition, or of actual economic injury. ``(2) Definitions.--(A) For purposes of paragraph (1), a mark is famous if it is widely recognized by the general consuming public of the United States as a designation of source of the goods or services of the mark's owner. In determining whether a mark possesses the requisite degree of recognition, the court may consider all relevant factors, including the following: ``(i) The duration, extent, and geographic reach of advertising and publicity of the mark, whether advertised or publicized by the owner or third parties. ``(ii) The amount, volume, and geographic extent of sales of goods or services offered under the mark. ``(iii) The extent of actual recognition of the mark. ``(iv) Whether the mark was registered under the Act of March 3, 1881, or the Act of February 20, 1905, or on the principal register. ``(B) For purposes of paragraph (1), `dilution by blurring' is association arising from the similarity between a mark or trade name and a famous mark that impairs the distinctiveness of the famous mark. In determining whether a mark or trade name is likely to cause dilution by blurring, the court may consider all relevant factors, including the following: ``(i) The degree of similarity between the mark or trade name and the famous mark. ``(ii) The degree of inherent or acquired distinctiveness of the famous mark. ``(iii) The extent to which the owner of the famous mark is engaging in substantially exclusive use of the mark. ``(iv) The degree of recognition of the famous mark. ``(v) Whether the user of the mark or trade name intended to create an association with the famous mark. ``(vi) Any actual association between the mark or trade name and the famous mark. ``(C) For purposes of paragraph (1), `dilution by tarnishment' is association arising from the similarity between a mark or trade name and a famous mark that harms the reputation of the famous mark. ``(3) Exclusions.--The following shall not be actionable as dilution by blurring or dilution by tarnishment under this subsection: ``(A) Any fair use, including a nominative or descriptive fair use, or facilitation of such fair use, of a famous mark by another person other than as a designation of source for the person's own goods or services, including use in connection with-- ``(i) advertising or promotion that permits consumers to compare goods or services; or ``(ii) identifying and parodying, criticizing, or commenting upon the famous mark owner or the goods or services of the famous mark owner. ``(B) All forms of news reporting and news commentary. ``(C) Any noncommercial use of a mark. ``(4) Burden of proof.--In a civil action for trade dress dilution under this Act for trade dress not registered on the principal register, the person who asserts trade dress protection has the burden of proving that-- ``(A) the claimed trade dress, taken as a whole, is not functional and is famous; and ``(B) if the claimed trade dress includes any mark or marks registered on the principal register, the unregistered matter, taken as a whole, is famous separate and apart from any fame of such registered marks. ``(5) Additional remedies.--In an action brought under this subsection, the owner of the famous mark shall be entitled to injunctive relief as set forth in section 34. The owner of the famous mark shall also be entitled to the remedies set forth in sections 35(a) and 36, subject to the discretion of the court and the principles of equity if-- ``(A) the mark or trade name that is likely to cause dilution by blurring or dilution by tarnishment was first used in commerce by the person against whom the injunction is sought after the date of enactment of the Trademark Dilution Revision Act of 2006; and ``(B) in a claim arising under this subsection-- ``(i) by reason of dilution by blurring, the person against whom the injunction is sought willfully intended to trade on the recognition of the famous mark; or ``(ii) by reason of dilution by tarnishment, the person against whom the injunction is sought willfully intended to harm the reputation of the famous mark. ``(6) Ownership of valid registration a complete bar to action.--The ownership by a person of a valid registration under the Act of March 3, 1881, or the Act of February 20, 1905, or on the principal register under this Act shall be a complete bar to an action against that person, with respect to that mark, that-- ``(A)(i) is brought by another person under the common law or a statute of a State; and ``(ii) seeks to prevent dilution by blurring or dilution by tarnishment; or ``(B) asserts any claim of actual or likely damage or harm to the distinctiveness or reputation of a mark, label, or form of advertisement. ``(7) Savings clause.--Nothing in this subsection shall be construed to impair, modify, or supersede the applicability of the patent laws of the United States.''; and (2) in subsection (d)(1)(B)(i)(IX), by striking ``(c)(1) of section 43'' and inserting ``(c)''. SEC. 3. CONFORMING AMENDMENTS. (a) Marks Registrable on the Principal Register.--Section 2(f) of the Trademark Act of 1946 (15 U.S.C. 1052(f)) is amended-- (1) by striking the last two sentences; and (2) by adding at the end the following: ``A mark which would be likely to cause dilution by blurring or dilution by tarnishment under section 43(c), may be refused registration only pursuant to a proceeding brought under section 13. A registration for a mark which would be likely to cause dilution by blurring or dilution by tarnishment under section 43(c), may be canceled pursuant to a proceeding brought under either section 14 or section 24.''. (b) Opposition.--Section 13(a) of the Trademark Act of 1946 (15 U.S.C. 1063(a)) is amended in the first sentence by striking ``as a result of dilution'' and inserting ``the registration of any mark which would be likely to cause dilution by blurring or dilution by tarnishment''. (c) Cancellation.--Section 14 of the Trademark Act of 1946 (15 U.S.C. 1064) is amended, in the matter preceding paragraph (1) by striking ``, including as a result of dilution under section 43(c),'' and inserting ``, including as a result of a likelihood of dilution by blurring or dilution by tarnishment under section 43(c),''. (d) Marks for the Supplemental Register.--The second sentence of section 24 of the Trademark Act of 1946 (15 U.S.C. 1092) is amended to read as follows: ``Whenever any person believes that such person is or will be damaged by the registration of a mark on the supplemental register-- ``(1) for which the effective filing date is after the date on which such person's mark became famous and which would be likely to cause dilution by blurring or dilution by tarnishment under section 43(c); or ``(2) on grounds other than dilution by blurring or dilution by tarnishment, such person may at any time, upon payment of the prescribed fee and the filing of a petition stating the ground therefor, apply to the Director to cancel such registration.''. (e) Definitions.--Section 45 of the Trademark Act of 1946 (15 U.S.C. 1127) is amended by striking the definition relating to the term ``dilution''. Speaker of the House of Representatives. Vice President of the United States and President of the Senate.

Trademark Dilution Revision Act of 2006 - Amends the Trademark Act of 1946 to revise provisions relating to trademark dilution. Entitles an owner of a famous mark that is distinctive to an injunction against another person who commences use of a mark of trade name, after it has become famous, in commerce in a manner that is likely to cause dilution by blurring or tarnishment, regardless of the presence or absence of actual or likely confusion, competition, or actual economic injury. Defines a mark as famous if it is widely recognized by the general consuming public as a designation of the source of the goods or services of the mark's owner. Allows the court to consider all relevant factors when determining whether a mark is famous, including: (1) the duration, extent, and geographic reach of advertising and publicity of the mark; (2) the amount, volume, and geographic extent of sales of goods or services offered under the mark; (3) the extent of actual recognition of the mark; and (4) whether the mark was registered under the Act of March 3, 1881, or the Act of February 20, 1905, or on the principal register. Defines "dilution by blurring" as an association arising from the similarity between a mark or trade name and a famous mark that impairs the distinctiveness of the famous mark. Allows the court to consider all relevant factors when determining whether a mark or trade name is likely to cause dilution by blurring, including: (1) the degree of similarity; (2) the degree of inherent or acquired distinctiveness of the famous mark; (3) the extent to which the owner of the famous mark is engaging in substantially exclusive use of the mark; (4) the degree of recognition of the famous mark; (5) whether the user of the mark or trade name intended to create an association with the famous mark; and (6) any actual association between the mark or trade name and the famous mark. Defines "dilution by tarnishment" as an association arising from the similarity between a mark or trade name and a famous mark that harms the reputation of the famous mark. Declares that certain acts are not actionable as dilution by blurring or tarnishment, including: (1) any fair use of a famous mark by another person other than as a designation of source for the person's own goods or services, including for advertising or promotion that permits consumers to compare goods or services, or identifying and parodying, criticizing, or commenting upon the famous mark owner or the owner's goods or services; (2) all forms of news reporting and news commentary; and (3) any noncommercial use of a mark. Requires the person who asserts trade dress protection for trade dress not registered on the principal register in a civil action for trade dress dilution to prove that: (1) the claimed trade dress, taken as a whole, is not functional and is famous; and (2) if the claimed trade dress includes any mark or marks registered on the principal register, the unregistered matter, taken as a whole, is famous separate and apart from any fame of such registered marks. Allows the owner of a famous mark to seek additional remedies in an action under this Act if the person against whom the injunction is sought: (1) first used the mark or trade name in commerce after the date of enactment of this Act; (2) willfully intended to trade on the recognition of the famous mark; or (3) willfully intended to harm the reputation of the famous mark. Declares that ownership of a valid registration is a complete bar to an action under state common law or statute that seeks to prevent dilution by blurring or tarnishment or that asserts any claim of actual or likely damage or harm to the distinctiveness or reputation of a mark, label, or form of advertisement.

the asymmetric simple exclusion process ( asep ) is a simple hard core hopping particle model . it consists of a line segment with @xmath1 sites . particles are allowed to hop on to site 1 if it is empty , with rate @xmath2 . any particles on sites @xmath3 to @xmath4 hop on to a site to their right if it is empty , with rate @xmath3 . a particle on site @xmath1 hops off with rate @xmath5 as illustrated in figure [ fig : asep ] . the state of the system at any time is defined by the set of indicator variables @xmath6 , where @xmath7 and the probability , @xmath8 of the system being in state @xmath9 , at time @xmath10 given some initial state at @xmath11 , satisfies a master equation ( see @xcite for details ) . for a review of the extensive literature on this model see derrida @xcite . a significant step forward in the understanding of the mathematical aspects of the model was made with the realization , by derrida et al @xcite , that a stationary state solution , @xmath12 , of the master equation could be determined by the matrix product ansatz @xmath13 with normalisation factor @xmath14 given by @xmath15 provided that @xmath16 and @xmath17 satisfy the dehp algebra [ algebra ] @xmath18 these equations are sufficient to determine @xmath19 but derrida et al @xcite also gave several interesting matrix representations of @xmath16 and @xmath17 and the vectors @xmath20 and @xmath21 , any one of which may be used to determine @xmath19 . the primary result of this paper is to show that each of the three matrix representations of the dehp algebra can be interpreted as a transfer matrix for a different weighted lattice path problem . this then allows the normalisation , correlation function and other properties of the asep model to be interpreted combinatorially as certain weighted lattice path configuration sums see section 2 . one of the path connections is similar to that discussed in derrida et . @xcite the lattice path interpretation has two primary consequences : the first is that it provides a starting point for a new method ( the `` constant term '' or ct method ) for calculating the normalisation and correlation functions see section 3 . this reproduces several existing results ( but by a new method ) and also provides several new results . one of note , the `` @xmath0-expansion '' , arises from a rearrangement of the constant term expression which leads to form of the normalisation in terms of the variables @xmath22 and @xmath23 . the coefficients in this expansion are catalan numbers , the asymptotic form of which enables a uniform approach to computing the asymptotic behaviour of @xmath14 as @xmath24 in the various phases of the asep model see section 5 . the results agree with those found in @xcite , by steepest descent methods . a bonus following from the lattice path interpretation of the algebra representations is that one of the lattice path interpretations ( a slight variation of representation 3 ) has a natural interpretation as a polymer chain having a two parameter @xmath25 interaction with a surface . in this context @xmath14 is a partition function for the `` two - contact '' polymer model see section 4 . we also obtain recurrence relations ( on the length variable ) for the partition function of this polymer model and hence also for the asep normalisation . the second primary consequence of the lattice path interpretation follows from the ct method itself , as the ct method has very natural combinatorial interpretations . for example , the normalisation can be written in several different polynomial forms depending on which variables you use : @xmath26 where all the polynomial coefficients , @xmath27 , are integers . ( all the variables in these polynomials are related by simple equations eg . @xmath28 , @xmath29 etc . see above and in later sections ) . since , in each of these cases , the normalisation arises from a weighted lattice configuration sum , all the above coefficients have a direct combinatorial interpretation as enumerating a particular subset of the paths ( eg . those with exactly @xmath30 steps with the first weight and exactly @xmath31 steps with the second weight ) . however , we show that each of the above polynomial coefficients has an alternative combinatorial interpretation which corresponds to enumerating a different , _ unweighted _ , set of lattice paths eg . in @xcite the coefficient , @xmath32 was given as @xmath33 which , with a simple rearrangement , can be seen to be a particular `` ballot number '' @xmath34 where @xmath35 enumerates ballot paths ( see section 3.1 for details ) of length @xmath10 and height @xmath36 . thus @xmath37 which enumerates a special set of paths with @xmath30 weights of type @xmath38 and @xmath39 weights of type @xmath40 is seen to be determined in terms of the much simpler combinatorial problem of enumerating _ unweighted _ ballot paths of length @xmath41 and height @xmath42 . this correspondence between between the two combinatorial problems ( one pair for each coefficient ) arises as a bijection between the two path problems . this result may be turned around : if a bijection between a particular ballot path problem and the weighted path problem can be proved then it provides an alternative derivation of the normalisation polynomial . finally , in section 6 , the recurrence relations for the asep correlation functions derived in @xcite are shown to follow from the lattice path interpretations . the coefficients of the terms in the recurrence relation are also seen to be various ballot numbers . derrida et al @xcite , provided three different matrix representations for the asep algebra . representation one , @xmath43 @xmath44 where @xmath45 representation two , @xmath46 @xmath47 where @xmath48 and representation three @xmath49 @xmath50 where @xmath51 since these matrices and vectors satisfy the algebraic relations , the normalisation factor for the asep model , can be evaluated using any of the three formulae @xmath52 and @xmath17 matrices on the square lattice , b ) the labelling of the matrix elements.__,title="fig : " ] each of these three representations can be interpreted as the transfer matrix of a particular weighted lattice path problem . if the rows of the @xmath53 matrix and the columns of the @xmath54 matrix are labelled with odd integers @xmath55 and the columns of @xmath53 and rows of @xmath54 are labelled with even integers @xmath56 , then @xmath57 is the weight of a step from an odd height @xmath58 to even height @xmath59 and @xmath60 is the weight of a step from an even height @xmath61 to an odd height @xmath59 . since the rows and columns are labelled with non - negative integers the steps are only in the upper half of @xmath62 . similarly , the elements of @xmath63 and @xmath64 are labelled by @xmath65 and are the weights attached to the initial and final vertices of the paths . the matrices @xmath53 and @xmath54 act successively to the left on the initial vector @xmath63 and @xmath66 is the weighted sum over all paths of length @xmath67 which begin and end at odd height above the @xmath68axis . an example path for each of the three representations is shown in figure [ fig : repex ] . notice that for the first representation the paths with non - zero weight begin at any odd height and end at unit height , for the second they both begin and end at any odd height and for the third they begin and end at unit height . all these paths are defined explicitly below . + derrida et . al . gave another expression for the normalisation factor ( see equation ( 39 ) of @xcite ) . this form does not arise directly from any of the above three representations , however , we will show ( corollary [ alphabeta ] ) that it is the partition function @xmath69 , defined in , corresponding to a `` canonical '' path representation ( see figure [ fig : canp ] for an example ) . in @xcite we provide a combinatorial derivation of the equivalence of the above three and a number of other path representations of the normalisation factor to the `` canonical '' representation . we consider paths whose steps are between the vertices of the half plane square lattice @xmath70 , where @xmath71 ( resp . @xmath72 ) is the set of integers ( resp . non - negative integers ) . a * lattice path * , @xmath73 , of length @xmath74 is a sequence of vertices @xmath75 where @xmath76 , and for @xmath77 , @xmath78 where @xmath79 is the set of allowed steps . for a particular path , @xmath73 , denote the corresponding sequence of steps by @xmath80 , @xmath81 . a * subpath * of length @xmath58 of a lattice path , @xmath73 , is a path defined by a subsequence of adjacent vertices , @xmath82 , of @xmath73 . the set of length @xmath67 * dyck * paths , @xmath83 ; length @xmath84 and height @xmath36 * ballot * paths @xmath85 , and length @xmath84 and heights @xmath86 and @xmath87 * cross * paths @xmath88 all have step set @xmath89 . dyck paths have @xmath90 and @xmath91 , ballot paths have @xmath90 and @xmath92 and cross paths have @xmath93 and @xmath94 , @xmath95 . denote , @xmath96 [ defn : bub ] an * elevated dyck path * or * bubble * , is a subpath , @xmath97 , @xmath98 , for which @xmath99 and @xmath100 for all @xmath101 , @xmath102 . if @xmath103 then the elevated dyck path is a single vertex . the subset @xmath104 of * anchored cross paths * is defined as all the paths in @xmath105 with at least one vertex in common with the line @xmath106 . denote , @xmath107 the set of * one up * paths , @xmath108 is the set of lattice paths of length @xmath67 which have step set @xmath89 , @xmath109 and @xmath110 , i.e. @xmath111 . [ def : js ] the set of * jump step * paths of length @xmath84 , @xmath112 , is the set of lattice paths which have step set @xmath113 with @xmath114 , @xmath115 , @xmath116 . the `` height '' , @xmath117 , of a step @xmath118 is defined as @xmath119 . odd steps with @xmath120 will be called `` jump '' steps . if @xmath121 ( resp . @xmath122 ) the step is called an `` up '' ( resp . `` down '' ) step . denote , @xmath123 _ note : _ jump step paths never visit the @xmath124-axis since such a visit can only occur on an odd step and return to @xmath106 is impossible since all even steps are down . [ def : mh ] * hovering * paths , @xmath125 are one up paths with no vertex on the @xmath124-axis . * separated hovering * paths , @xmath126 , @xmath127 , are the subset of the hovering paths which have @xmath128 . the vertex @xmath129 is marked ( with an empty circle see figure [ fig : allpaths]f ) and known as the * separating vertex*. * marked separated hovering * paths , @xmath130 , are obtained from @xmath126 by marking ( with an solid circle see figure [ fig : allpaths]i ) subsets of the steps ( or vertices ) which return to @xmath106 . _ note : _ for all paths considered @xmath131 is either odd for all @xmath132 or even for all @xmath132 , i.e. the paths are confined either to the odd sublattice or the even sublattice . [ defn : ret ] a vertex of a ballot or dyck path in common with the @xmath124-axis is called a * contact*. all contacts except the initial one are called * returns*. the polynomial @xmath133 , where @xmath134 is the number of returns for the path @xmath73 , is called the * return polynomial * for ballot paths . for each of the three different representations the following lemma converts the matrix formula for the normalization factor into a sum over one of the path sets defined above , where the summand is a product of the step weights @xmath135 , an initial vertex weight @xmath136 , and a final vertex weight @xmath137 . the normalisation factor , @xmath138 for each of the three matrix representations , @xmath139 , can be written as @xmath140w^{f}_{j}(v_{2r})\label{eq:449}\end{aligned}\ ] ] where @xmath141 , @xmath142 , and @xmath143 , and the weight @xmath144 of a particular path @xmath73 with step sequence , @xmath145 is defined , for each of the three cases , as follows . for @xmath146 [ jweights ] @xmath147 for @xmath148 @xmath149 and for @xmath150 [ eqs : w2 ] @xmath151 the above lemma is a direct consequence of the lattice path interpretation of the @xmath53 and @xmath54 matrices as transfer matrices . the equivalence of the different expressions is a consequence of the invariance of the normalisation factor under similarity transformations relating the different matrix representations of @xmath16 and @xmath17 . in order to compute @xmath152 , it turns out to be a little more convenient to rearrange the weights associated with representation three . if we do so we obtain the following corollary . an equivalent set of weights for @xmath152 , is @xmath153 _ note : _ this rearrangement of the weights is only valid for computing @xmath152 . for correlation functions one has less freedom in the weight rearrangement . _ , title="fig : " ] later in the paper ( corollary [ alphabeta ] ) we will show that the normalisation factor can also be expressed in terms of separated hovering paths . @xmath154 where @xmath155 is defined by with [ eqs : w5 ] @xmath156 thus , for any particular path , @xmath157 , all the @xmath158 weighted steps ( if any ) occur to the left of vertex @xmath159 and all the @xmath160 weighted steps ( if any ) occur to the right of @xmath159 . we call this combination of paths and weights the `` canonical '' path representation of the normalisation factor . an example is shown in figure [ fig : canp ] . let @xmath161 be the set of marked separated hovering paths obtained from @xmath126 by marking subsets of the steps which return to @xmath106 then @xmath162 where the weight @xmath163 has a factor @xmath164 for each marked return step which occurs to the the left of @xmath129 and a factor @xmath165 for the other marked return steps . the lemma is proved in @xcite in two stages . first an involution on @xmath166 for which @xmath167 is the fixed set and then a bijection between @xmath167 and @xmath168 . [ z2z5 ] @xmath169 substituting @xmath170 in the weight attached to a path @xmath171 and expanding leads to a sum of terms obtained by weighting each return step to the right of @xmath129 ( if any ) with either @xmath3 or @xmath165 and the remaining returns ( if any ) by @xmath3 or @xmath164 . marking the subsets of steps weighted @xmath164 or @xmath165 determines a set of paths belonging to @xmath161 . in this section we briefly review methods to be used and results obtained previously @xcite as they will be required in the next section . one additional new lemma is stated . the constant term operation , @xmath172 $ ] , is defined by @xmath173 = \text { the constant term in the laurent expansion of $ f(z)$ about $ z=0$.}\ ] ] the number of @xmath174step lattice paths with step set @xmath175 which begin at @xmath176 and end at @xmath177 with no further constraint ( i.e. replacing the constraint @xmath178 in the definition of @xmath179 by @xmath180 ) is the binomial coefficient @xmath181 for which the constant term formula is @xmath182.\ ] ] by the reflection principle @xcite , the number of @xmath174step ballot paths of height @xmath36 is obtained by subtracting the number of unrestricted paths which begin at @xmath183 from those beginning at @xmath176 , both ending at @xmath184 . @xmath185 - ct[(z + 1/z)^t z^{h+2 } ] = ct[\la^t z^h ( 1-z^2)]\ ] ] where @xmath186 . differencing the binomial coefficients expresses @xmath187 in terms of factorials ; for @xmath188 even @xmath189 dyck paths are ballot paths ending at @xmath190 so the number dyck paths with @xmath67 steps is @xmath191 , @xmath192 all of which are solved by @xmath193 $ ] . historically , ballot numbers arise in the combinatorial problem of a two candidate election . if you ask how many ways can @xmath84 votes be caste such that the first candidate ends @xmath36 votes ahead of the second candidate and at any stage of the voting never has fewer votes that the second candidate . previously @xcite we proved the following proposition concerning the return polynomial ( see definition [ defn : ret ] ) . the return polynomial for ballot paths of length @xmath84 and height @xmath36 is given by @xmath194\ ] ] for @xmath195 , @xmath196 is determined by the recurrence relations @xmath197 the first and last equations are the same as for the unweighted ballot paths and are satisfied by @xmath198 $ ] provided that on expansion @xmath199 has no negative powers and @xmath200 ( which will be the case ) . we have introduced the factor @xmath199 to allow the second equation to be satisfied . but @xmath201 and choosing @xmath202 @xmath203&= & ct[\la^{t-1}(z+1/z)(1-z^2)g(z)]\\ & = & { \kappa}ct[\la^{t-1 } z ( 1-z^2 ) g(z ) ] + ct[\la^{t-1}(1/z -z)].\end{aligned}\ ] ] the result follows since the last term may be evaluated to give zero . @xmath204 the first equality follows by expanding in powers of @xmath205 and using . the second is obtained by rewriting the constant term formula as @xmath206\ ] ] and then expanding in powers of @xmath207 . and height @xmath208 . _ , title="fig : " ] this result suggests a bijection between ballot paths of length @xmath84 with @xmath30 returns and ballot paths of length @xmath209 and height @xmath210 and hence suggests a combinatorial proof . such a bijection was given in @xcite . a ballot path can be represented schematically as shown in figure [ fig : bal ] . the bubbles ( see definition [ defn : bub ] ) represent a , possibly empty , arbitrary elevated dyck path . using this schematic representation , proving is then straightforward . for simplicity we show the bijection in the case @xmath211 in figure [ fig : bp ] . b ) all return steps deleted c ) first step deleted produces a ballot path of height @xmath42 and length @xmath41.__,title="fig : " ] the expansion in powers of @xmath212 was also obtained by bijection in @xcite . in this case the bijection is between ballot paths with at least @xmath30 returns , @xmath30 of which are marked , and ballot paths of the same length but of height @xmath213 . with @xmath214 marked returns and b ) its schematic representation in terms of bubbles . c ) each marked return rotated through 90 degrees anti - clockwise ( or equivalently replaced by an up step ) producing a ballot path of height @xmath215 and length @xmath84.__,title="fig : " ] the above methodology is typical of that used for the more complicated two parameter case in the next section . a constant term formula will be derived and then rewritten in four different ways each giving rise to an expansion in pairs of different variables the coefficients of which are ballot numbers and are shown , by bijection , to enumerate various types of lattice path . in the next section we will also need the following lemma . [ lem : ret]let @xmath216 be the set of separated hovering paths ( definition [ def : mh ] ) then @xmath217 since we can shift any hovering path down on to the @xmath124-axis to give a dyck path with vertex @xmath218 marked , the lemma says the number of dyck paths with one contact marked is equal to the number of ( unmarked ) dyck paths two steps longer . a sketch of the bijective combinatorial proof is shown in figure [ fig : mc ] . the construction is a bijection , since , given any length @xmath219 dyck path a unique length @xmath220 marked contact dyck path is determined by deleting the rightmost step and the rightmost step from @xmath221 to @xmath106 ( and marking the left vertex of the latter step ) . ) and c ) adding a final down step produces a unique dyck path of length @xmath219__,title="fig : " ] we begin by computing @xmath152 using the @xmath222 weights we will refer to this as the two contact model . we will generalise the model by allowing arbitrary starting and ending heights for the paths . in particular , let the paths be of length @xmath84 , start at @xmath223 with @xmath224 and terminate at @xmath225 , @xmath226 , i.e. cross paths in @xmath227 . this model can also be thought of as a polymer model with two different surface interactions , or `` contacts '' . the path interacts with the `` thickened '' surface @xmath228 via two parameters , @xmath229 and @xmath230 and the partition function is defined by @xmath231 where the sum is over cross paths of length @xmath84 with given initial and final heights @xmath232 and @xmath233 and the weight @xmath234 is defined by and . this is a generalisation of the asep partition function @xmath152 thus @xmath235 this generalisation allows this partition function to be determined by recurrence relations similar to those for the return polynomial of ballot paths . by considering paths of length @xmath236 which can reach the point @xmath177 by adding one more step the partition function @xmath237 may be seen to satisfy the equations , @xmath238 these partial difference equations can be solved for @xmath237 by using the constant term method . [ prop1 ] with @xmath239 , @xmath240 and @xmath241 , for @xmath242 and @xmath243 @xmath244 + ( \delta_{y^i,1}+\k_2(1-\delta_{y^i,1}))ct[z^{y+y^i-2}\la^t g(z)]\ ] ] where @xmath245 _ note : _ for @xmath246 and @xmath243 @xmath247 substituting into the partial difference equations and noting that @xmath248 may be expanded in even powers of @xmath249 with no inverse powers shows that , and are satisfied . may be taken as the definition of @xmath250 and may then be transformed into @xmath251 to verify that this equation is also satisfied we note that @xmath252 in the case @xmath253 this gives @xmath254 & = ct[\la^{t-1}(1/z - z ) ] + \k_1{z}_{t-2 } ( 1|y^i;\k_1,\k_2)+\k_2{z}_{t-1 } ( 2|y^i;\k_1,\k_2)\end{aligned}\ ] ] and follows since the first term is zero . otherwise @xmath255 in which case @xmath256 + \k_2 ct[z^{y^i}\la^{t-1 } g(z)]\ ] ] and using this together with and the fact that the first term in vanishes when @xmath106 @xmath257\\ & = \k_2 ct[z^{y^i-1}(1/z - z)\la^{t-1}]+\k_1{z}_{t-2 } ( 1|y^i;\k_1,\k_2 ) + \k_2 ^ 2ct[z^{y^i}\la^{t-1}g(z)]\\ & = \k_2 ct[(z^{y^i-2}-(1/z)^{y^i-2})\la^{t-1}]+\k_1{z}_{t-2 } ( 1|y^i;\k_1,\k_2 ) + \k_2{z}_{t-1 } ( 2|y^i;\k_1,\k_2)\end{aligned}\ ] ] and again follows since the first term evaluates to zero . an alternative constructive proof of this proposition is given in appendix b. [ crosspaths ] the number of @xmath174step cross paths which begin at @xmath258 and end at @xmath259 is given by @xmath260\\ \intertext{is the partition function restricted to anchored cross paths except that for $ y^i>1 $ the step leading to the first visit to $ y=1 $ has weight $ 1$. } \intertext{in particular } \label{z11 } { z}_t(y|1;\k_1,\k_2 ) & = \za_t(y|1;\k_1,\k_2 ) = ct\left[\la^t g(z)z^{y-1}\right].\end{aligned}\ ] ] _ notes : _ * it follows from the constant term formula that @xmath261 * setting @xmath262 gives the number of unweighted paths starting at height @xmath3 . @xmath263 = b_{t+1,y}\ ] ] as expected since the paths biject to ballot paths by adding an initial up step . with @xmath264 , @xmath265 and substituting in gives @xmath266\ ] ] which yields . @xmath267 is the number of cross paths which avoid @xmath106 . this follows since such paths are in simple bijection with the paths starting at height @xmath268 and ending at height @xmath269 , eg . just push the whole path down ( or up ) two units . the second term in is therefore the partition function for anchored cross paths . in the case @xmath270 anchored cross paths always have a first visit to @xmath106 and the step leading to this visit has a factor @xmath230 . removing this factor leaves @xmath271 which is therefore the partition function for anchored cross paths except that for @xmath272 the step leading to the first visit to @xmath106 has weight @xmath3 . setting @xmath273 in gives since the first term vanishes . [ cor : bp3]@xmath274\\ & \notag\\ & = \sum_{j=0}^{(t - y - y^i)/2 + 1}\quad\sum_{k=0}^{(t - y - y^i)/2-j+1}\k_1^j \k_2^k\ , \binom{j+k}{k}\ , b_{t-2j - k-1,y+y^i+k-3}\label{k12}\end{aligned}\ ] ] _ note:_when @xmath275 and @xmath276 the coefficient @xmath277 is indeterminate but setting @xmath278 gives the correct answer . this corresponds to the path which alternates between @xmath221 and @xmath106 . notice that replacing the factorials in the definition of @xmath187 by gamma functions gives @xmath279 for all @xmath280 . rewrite @xmath248 in the form @xmath281 expand in powers of @xmath229 and @xmath230 and use the ct formula for ballot numbers . equation may also be proved by a combinatorial argument . to simplify the proof we only consider the asep case @xmath282 . the extension to general @xmath283 , @xmath232 is straightforward . recall that , from the weight definition , , the returns to @xmath106 are weighted with @xmath284 or @xmath285 depending on whether the return is from below or from above @xmath106 . the binomial coefficient corresponds to choosing a particular sequence of @xmath286 and @xmath287 weighted returns . for each particular sequence of returns we need to show there are @xmath288 possible path configurations . we first represent a particular sequence schematically and then show any path corresponding to the schematic can be bijected to a ballot path with the correct height and length . schematically an example of a particular sequence of @xmath286 and @xmath287 returns is shown in figure [ fig : k1k2seq ] . . _ , title="fig : " ] we now perform three operations to biject a given sequence into a ballot path . * first delete all @xmath287 return steps , see figure [ fig : k1k2bij]a ) . this produces a path of length @xmath289 and height @xmath290 . * next , delete the first up step above @xmath106 ( if any which is the case if @xmath102 ) , see figure [ fig : k1k2bij]b ) . this produces a path of length @xmath291 and height @xmath58 . * finally , delete all @xmath292 steps originally below @xmath106 , see figure [ fig : k1k2bij]c ) . this produces a ballot path of length @xmath293 and height @xmath294 as required . given the sequence of @xmath286 and @xmath287 the reverse direction for the bijection is obtained by simply reversing the forward mapping see figure [ fig : k1k2bij ] . to a ballot path : a ) delete all @xmath287 return steps , then b ) delete first up step above @xmath106 , then c ) delete all steps originally below @xmath106 , to give d ) the final ballot path . _ , title="fig : " ] [ cor : bp2 ] @xmath295 rewrite @xmath248 in the form @xmath296 expand in powers of @xmath297 and @xmath298 and use the ct formula for ballot numbers . as with corollary [ cor : bp3 ] , the result , , may also be proved combinatorially as follows . again , in order to simplify the proof we consider only the asep case @xmath275 . the substitution @xmath299 means that a return which was weighted with @xmath300 is now weighted with either @xmath301 or @xmath3 . the factor @xmath302 is the number of paths with a subset of exactly @xmath61 of the returns from below marked and exactly @xmath58 of the returns from above marked corresponding to the choice of weight @xmath301 or @xmath3 . the binomial coefficient in is the number of ways of choosing a particular sequence of @xmath303 and @xmath304 weighted marks ( reading the path from left to right ) , whilst , for a given sequence , the ballot number represents the number of paths corresponding to the sequence . marked . c ) schematic one up path with only the last step @xmath304 marked . d ) an example showing how the schematic frying pan represents a , possibly empty , one up path . e ) an example showing a frying pan followed by a down step and an up step ( which forms a @xmath303 marked return ) . f ) an example showing a frying pan followed by an up step , then a bubble then a final down step ( which forms a @xmath304 marked return ) . _ , title="fig : " ] the most general path corresponding to a given sequence can be represented schematically by concatenating the corresponding schematic sub - paths shown in figure [ fig : fps]a ) and [ fig : fps]b ) with a final `` frying pan '' shown in figure [ fig : fps]c ) . examples of sub - paths corresponding to the three types of schematics are illustrated in figures [ fig : fps]d ) [ fig : fps]f ) . note , the shaded regions of the schematics represent any number ( possibly zero ) of steps . examples of two possible sequences are illustrated in figure [ fig : kbs ] . thus , for a given return sequence we need to show that there are @xmath305 return marked paths . without loss of generality we choose a typical sequence and represent it schematically as shown in figure [ fig : kbs ] . @xmath304 marked hovering path . a ) for the sequence @xmath306 and b ) for the sequence @xmath307.__,title="fig : " ] thus to prove the ballot number factor in we need to biject any schematic marked return sequence to a ballot path of length @xmath308 and height @xmath309 . we do this by bijecting each schematic in the sequence to a sub - ballot path ( plus , possibly , an extra step ) and then concatenate them all together . * thus , the last frying pan , of length say , @xmath310 , bijects to a height @xmath3 , length @xmath311 ballot path see figure [ fig : dfg ] . + * a marked @xmath304 schematic of length @xmath312 bijects to a height @xmath313 , ballot path with an additional final up step ( see figure [ fig : kbo ] ) . the final length is @xmath314 as an extra step has to be added . + schematic to a height two ballot path , with a final up step . the final path is one step longer than the original.__,title="fig : " ] * finally , a marked @xmath303 schematic of length @xmath315 bijects to a height @xmath3 , ballot path with an additional final up step ( see figure [ fig : kbt ] ) . the final length is unchanged . + schematic to a height one ballot path , with a final up step . _ , title="fig : " ] putting these moves all together is illustrated in figure [ fig : kbokbt ] , which show clearly a ballot path of length @xmath308 and height @xmath316 is obtained . and @xmath317 steps and a ballot path . a ) the marked one up path . b ) after the application of move illustrated in figure [ fig : kbt ] . c ) after the application of move illustrated in figure [ fig : kbo ] . e ) final ballot path after rotating the remaining marks . _ , title="fig : " ] an explicit evaluation of the partition function of the canonical path representation , defined by , is the case @xmath318 of the following result . [ alphabeta ] with @xmath319 and @xmath320 @xmath321 _ notes : _ * for the asep model ( @xmath322 ) with @xmath323 , reduces to the result of derrida et al @xcite equation ( 39 ) @xmath324 which they obtained directly from the algebra ( @xcite appendix a1 , equation ( a12 ) ) without the use of a matrix representation . * the result for the asep model may be written in terms of the return polynomial for ballot paths , thus @xmath325 this formula may also be derived using a path representation based on recurrence relations of derrida , domany and mukamel @xcite . by definition of @xmath158 and @xmath160 @xmath326[1-({\bar{\beta}}-1)z^2]=z^2(\la-{\bar{\alpha}}z)(\la -{\bar{\beta}}z)\ ] ] and from @xmath327 the result follows by expanding in powers of @xmath158 and @xmath160 , substituting in and using the ct formula for ballot numbers . in the asep case @xmath322 the coefficient @xmath328 in is equal to the number of dyck paths with @xmath30 returns to @xmath221 ( see ) . the equality of @xmath329 with @xmath69 , defined by , follows by raising the dyck paths so that they become hovering paths @xmath330 with returns to @xmath106 . the factor @xmath331 in corresponds to weighting the first @xmath61 returns of @xmath73 with @xmath158 and the remainder with @xmath160 . the sum over @xmath10 in is obtained by partitioning the weighted paths according to the position @xmath332 of the @xmath333 return ( ie . the separation vertex ) . the equality of @xmath152 and @xmath69 is also shown directly in @xcite by involution . let @xmath334 and @xmath335 then @xmath336 , @xmath337 and @xmath338 _ note : _ equation is not given in @xcite but ( 34 ) and ( 35 ) of @xcite together give the related formula @xmath339 this expression involves an infinite series whereas our expression is finite . by corollary [ crosspaths ] the coefficient in is the number of cross paths of length @xmath67 with @xmath340 and @xmath341 and the double sum extends over @xmath342 . the factor @xmath343 restricts the sum to anchored cross paths . the equivalence of and is shown in @xcite by constructing an involution on @xmath342 having @xmath344 as is its fixed point set . from @xmath345 and substitution in gives @xmath346 the result follows from using the expansion @xmath347 expanding in powers of @xmath249 and using the ct formula for ballot numbers .. again a combinatorial proof is possible which for simplicity we only give in the asep case . the equality with @xmath348 follows from corollary [ z2z5 ] . to obtain the ballot number formula we obtain a bijection between @xmath349 and the set of ballot paths of length @xmath350 and height @xmath351 . an example of the schematic representation of a path @xmath352 with a given number of @xmath164 and @xmath165 marked return steps and a separating vertex @xmath353 is shown in figure [ fig : cdseq ] . as there are no steps below @xmath106 we have pushed the hovering path down by unit height and consider it as a dyck path . and @xmath165 marked returns and a marked separating vertex @xmath353 . _ , title="fig : " ] as in the proof of lemma [ lem : ret ] , inserting an up step in each path at the position of @xmath353 and taking the union over all possible positions of @xmath353 starting at the last @xmath164 return and up to but not including the first @xmath165 return ( or from the beginning if there are no @xmath164 returns and to the end if there are no @xmath165 returns ) replaces the pair of bubbles on either side of the separating vertex by the set ballot paths of height one and one step longer , see figure [ fig : cdbij]a , b ) . replacing each marked return step with an up step ( and hence increasing the height of the path by 2 each time ) then produces a ballot path of length @xmath350 and height @xmath354 as required , see figure [ fig : cdbij]c ) . and @xmath165 return by an up step produces a ballot path of length @xmath350 and height @xmath354 as in c ) . _ , title="fig : " ] [ cor6 ] @xmath355\ ] ] note : this converts to the integral formula of derrida et al @xcite ( b10 ) with @xmath356 and and using a contour integral to pick out the constant term . it is related to the @xmath73 expansion ( see later ) . ( b10 ) was obtained by finding the eigenvectors of @xmath357 and is therefore an evaluation of @xmath358 . with @xmath359 in and using @xmath360\ ] ] now symmetrize the denominator by multiplying numerator and denominator by @xmath361 . the result follows using @xmath362 because the rest of the expression is now symmetric the contribution from the last term vanishes by replacing @xmath363 by @xmath364 and both @xmath365 and @xmath366 can be replaced by @xmath367 . with @xmath369 corollary [ cor6 ] may be written in the form @xmath370.\ ] ] which may be expanded to give @xmath371 where @xmath372.\ ] ] the asymptotic form of @xmath373 as @xmath24 was obtained in @xcite and will now be used to study the phase diagram for the asep model . first we outline the method by which the asymptotic form was obtained . notice that expanding the factor @xmath374 in in powers of @xmath0 gives an infinite series which is only valid for @xmath375 which is the point at which @xmath0 as a function of @xmath164 passes through its maximum value @xmath376 . instead we use to obtain a recurrence relation . thus noting that @xmath377 and substituting in gives @xmath378 where @xmath379 is the catalan number , . solving with @xmath380 gives @xmath381 which on substituting for @xmath382 in terms of @xmath164 must give a polynomial in @xmath164 . for the asep model @xmath383 and @xmath384 so @xmath385\\ & = { \omega_c}^{-(r+1)}(1 - 2\alpha)\,\,\theta(1 - 2\alpha ) + \sum_{j = r}^\infty c_j{\omega_c}^{j - r}\end{aligned}\ ] ] where @xmath386 is the unit step function . this is @xcite equation ( 3.61 ) . the asymptotic form for @xmath387 was obtained using @xmath388 and approximating the sum by an integral with the result @xmath389 and hence @xmath390 as @xmath391 , @xmath392 and these results agree with @xcite equations ( 48)-(50 ) . in the phase diagram there are therefore * three special regions @xmath393 , @xmath394 , @xmath395 + the partition function @xmath396 is obtained from that in @xmath397 by interchanging @xmath398 and @xmath399 . * three special lines @xmath400 , @xmath401 , @xmath402 the partition function @xmath403 is obtained from that in @xmath404 by interchanging @xmath398 and @xmath399 . * a special point where the lines meet @xmath405 table [ tableo ] shows the asymptotic form of @xmath329 for the above cases [ tableo ] .asymptotic forms of @xmath329 in the regions defined in the phase diagram in figure [ fig : pd ] . [ cols="^,^,^ " , ] the various formulae for @xmath248 when substituted in yield recurrence relations for @xmath406 . for example , using the identity @xmath407 substitution in and using the ct formula for catalan numbers leads to , for @xmath408 @xmath409 substitution in terms of @xmath229 and @xmath230 yields , for @xmath410 @xmath411 which may be initialised by @xmath412 and @xmath413 . the following identity @xmath414 when substituted in gives , using the @xmath415 formula for ballot numbers , for @xmath416 and odd @xmath417 @xmath418 which relates partition functions on lines of constant @xmath419 . the partition function for @xmath106 is determined by and the following proposition then the determines @xmath420 which provides the initial condition for . for @xmath421 @xmath422 from corollary [ alphabeta ] , for @xmath421 @xmath423 and the result follows from corollary [ alphabeta ] with @xmath424 . finally , substituting the identity @xmath425 in and using leads to the recurrence , for @xmath426 , and odd @xmath427 @xmath428 which relates partition functions along lines of constant @xmath84 and may be initialised using the above relations to find the partition functions for @xmath429 and @xmath430 . the probability of finding particles at positions @xmath431 is , using , @xmath432 where the un - normalised @xmath31-point correlation function @xmath433 is given by @xmath434 where @xmath435 . this expression may be thought of as replacing @xmath436 by @xmath16 in @xmath437 at each of the positions @xmath438 which is equivalent to replacing the @xmath54 matrix in a @xmath439 product by a unit matrix . thus in the path representations @xmath433 is obtained by modifying the allowed step definition such that for @xmath440 , the step @xmath441 ( beginning at @xmath442 and ending at @xmath443 ) is always an up step and has weight @xmath3 . we will say that @xmath444 is a _ forced up step_. this is illustrated in figure [ fig : corrpath ] . -point correlation path interpretation ( @xmath445 is shown above ) : each step starting at @xmath442 , @xmath440 must be an up step with weight one.__,title="fig : " ] . in the case @xmath446 , or @xmath262 , it is shown in @xcite that @xmath447 a catalan number . this may also be seen in terms of the third path representation ( corresponding to the third matrix representation of section [ matrepsec ] ) . @xmath448 is just the total number of one up paths of length @xmath67 and these biject to dyck paths of length @xmath219 by adding an up step at the beginning and a down step at the end of each path ( the dotted steps in figure [ fig : corrpath ] ) . the result follows since number of dyck paths of length @xmath449 is well known to be the catalan number @xmath450 . the result also follows from by setting @xmath451 and noting that @xmath452 which is the @xmath453 term . it is also shown in @xcite , equation ( 88 ) that @xmath454 this may be derived combinatorially as follows . again we use the third path representation and to avoid special cases we imagine that the paths are extended to @xmath221 by a further down step . for each path which contributes to @xmath433 we determine a subpath @xmath455 which starts with the last forced up step , @xmath456 , and ends when the path returns to the same height for the first time . this subpath contains a bubble which we suppose has length @xmath457 so that the subpath has length @xmath458 see figure [ bubble1]a . immediate return corresponds to @xmath459 and the maximum value of @xmath460 is determined by the condition , @xmath461 , that there are no further steps beyond @xmath455 . , showing the bubble following the last forced up step . b ) removing the bubble leaves a shorter dyck path _ , title="fig : " ] we can now define a new path obtained by deleting @xmath455 and joining the two ( possibly empty ) resulting sub - paths which remain . this path contributes to @xmath462 . the result follows by partitioning the paths contributing to @xmath463 according to the value of @xmath460 . for a given value of @xmath460 the number of configurations is therefore the product @xmath464 and the number of configurations of @xmath455 which is equal to the number , @xmath465 , of dyck paths of length @xmath457 . for @xmath466 , let @xmath467 then as pointed out in @xcite , equation may be iterated or , combinatorially , @xmath31 bubbles may be removed , to give the explicit formula @xmath468 where the upper limits are @xmath469 with @xmath470 . this formula was previously conjectured by derrida and evans @xcite on the basis of computer calculations up to @xmath471 . equation ( 45 ) of @xcite is the case @xmath472 of the following proposition which we now prove using a lattice path representation . an algebraic proof was given in @xcite . for @xmath473 @xmath474 _ notes : _ * when @xmath475 this reduces to since using @xmath476 the second sum of is just the missing term @xmath477 of the first sum . * in constructing a proof it was found that the first representation in terms of jump - paths was simpler to use than the third which we used in the special case of the previous section . it was explained after definition [ def : js ] , that jump - step paths ( representing @xmath14 ) never intersect @xmath221 . however this is not the case in calculating @xmath433 since the paths are modified by the forced up steps . this allows @xmath221 to be visited and then a forced up step returns the path to @xmath106 . notice that the down step leading to @xmath221 has a weight @xmath160 . _ proof : _ partition the modified jump - step configurations according as the last forced up step , @xmath456 , which starts at height @xmath478 ( case a ) or @xmath221 ( case b ) see figure [ bubble2 ] . . b ) case b : last forced up step starts at @xmath221 . note , the `` bubbles '' represent jump step subpaths . _ , title="fig : " ] [ [ case - a ] ] case a : + + + + + + + a subpath @xmath455 may be identified in exactly the same way as in the case @xmath479 but in this case the bubble of length @xmath449 obtained by deleting the first and last steps of @xmath455 is not an elevated dyck path since it may contain jump steps . however the number of configurations of @xmath455 is still equal to @xmath480 ( see below ) for any value of @xmath58 and since @xmath455 avoids @xmath106 its steps are unweighted . thus on partitioning the paths according to the length @xmath481 of @xmath455 a factor @xmath480 may be removed from the sum over paths having the same value of @xmath482 . when @xmath455 is deleted the remaining steps form a weighted path of length @xmath483 which has only @xmath484 forced up steps . summing over configurations of this path for given @xmath58 and then summing over @xmath485 gives @xmath486 . the first term of the proposition formula is thus derived provided that we can show that the number of configurations of @xmath455 is @xmath480 . now the paths @xmath455 of length @xmath487 biject to @xmath488 by vertical translation through distance @xmath489 and from and @xmath490 the last equality follows since when @xmath491 the one up paths which visit @xmath221 have zero weight and the remaining paths , which have weight @xmath3 when @xmath492 , biject to dyck paths by vertical translation through unit distance . this result is also proved combinatorially in @xcite . [ [ case - b ] ] case b : + + + + + + + the weighted sum over paths may be factorised into three parts . * a factor which arises from the subpath consisting of the first @xmath493 steps . the subpath ends at @xmath106 and has only @xmath484 forced up steps , therefore the sum over these subpaths yields @xmath494 . * a factor @xmath160 which arises from the next two steps which visit @xmath221 and return to @xmath106 . the second of these is the last forced up step @xmath456 having weight @xmath3 . * a factor arising from the subpath consisting of the remaining @xmath495 steps which is a jump step path beginning and ending at @xmath106 , avoiding @xmath221 . the weighted sum over these paths is obtained by setting @xmath496 in the normalising factor for paths of length @xmath495 , thus using corollary [ alphabeta ] @xmath497 the product of these three factors yields the second term of the formula . we have shown that the normalisation of the asep can be interpreted as various lattice path problems . the lattice path problems can then be solved using the constant term method ( ctm ) . the combinatorial nature of the ctm enables us to interpret the coefficients of the normalisation polynomials as various un - weighted lattice path problems usually as ballot paths . one particular form has a natural interpretation as an equilibrium polymer chain adsorption model . the `` @xmath0 '' form of the normalisation is particularly suited to finding the asymptotic expansion of normalisation and hence the phase diagram . we also formulate a combinatorial interpretation of the correlation functions . the lattice path interpretations enable us to make connections with many other models . in particular , because of the strong combinatorial nature of the ctm we are able to find a new `` canonical '' lattice path representation . in a further paper @xcite we show that this representation leads to an understanding of a non - equilibrium model ( the asep model ) in terms of a related equilibrium polymer model . also , having extended the polymer chain model so that the endpoints have arbitrary displacements from the surface the method of gessel and viennot @xcite , @xcite ( see also @xcite ) may be used to express the partition function of a network of non - intersecting paths as a determinant . in particular , the case of two paths gives the partition function for a vesicle model with a two parameter interaction with a surface . a bijection between these vesicles and compact percolation clusters @xcite then enables an analysis of the properties of the clusters attached to damp wall to be made . these applications will also be the subject of a subsequent publication . it is also of combinatorial interest to understand how the various path problems might be related . clearly they are related algebraically as they are all just representations of the same algebra ( and thus related by different similarity transformations ) . in a subsequent paper , @xcite , we show combinatorially ( using bijections and involutions ) how the various path representations are combinatorially equivalent . financial support from the australian research council is gratefully acknowledged . jwe is also grateful for the kind hospitality provided by the university of melbourne and rb is also grateful for the kind hospitality provided by royal holloway college , london university . we would like to thank andrew rechnitzer and aleks owczarek for reading the manuscript and providing useful comments . * appendix * the formula @xmath499\ ] ] clearly satisfies the general equation and the initial condition provided that @xmath500=0.\ ] ] in order to satisfy the boundary condition @xmath501 = { \kappa}_1ct[\la^{t-2}z(\bar z^{y^i } + u(z ) z^{y^i})]+ { \kappa}_2 ct[\la^{t-1}z^2 ( z^{y^i } + u(z ) z^{y^i})]\ ] ] or @xmath502= -ct[\la^{t-2}v(z ) z^{y^i-1}]\ ] ] where @xmath503 replacing @xmath249 by @xmath504 everywhere under the ct operation leaves the value unchanged so @xmath505 and is satisfied provided that @xmath506 or @xmath272 since @xmath243 . hence in this case @xmath272 @xmath507 when @xmath273 the boundary condition is satisfied if @xmath508 \equiv ct[\la^{t-2}(\bar z^2 - 2+z^2 -{\kappa}_1-{\kappa}_2 ( 1+z^2))]= -ct[\la^{t-2}v(z)]\ ] ] and replacing @xmath509 by @xmath510 in the second expression gives @xmath511 which satisfies and hence @xmath512

we show that the known matrix representations of the stationary state algebra of the asymmetric simple exclusion process ( asep ) can be interpreted combinatorially as various weighted lattice paths . this interpretation enables us to use the constant term method ( ctm ) and bijective combinatorial methods to express many forms of the asep normalisation factor in terms of ballot numbers . one particular lattice path representation shows that the coefficients in the recurrence relation for the asep correlation functions are also ballot numbers . additionally , the ctm has a strong combinatorial connection which leads to a new `` canonical '' lattice path representation and to the `` @xmath0-expansion '' which provides a uniform approach to computing the asymptotic behaviour in the various phases of the asep . the path representations enable the asep normalisation factor to be seen as the partition function of a more general polymer chain model having a two parameter interaction with a surface . * pacs numbers : * 05.50.+q , 05.70.fh , 61.41.+e * key words : asymmetric simple exclusion process , lattice paths , constant term method , enumerative combinatorics *

the spectral energy distributions ( seds ) of blazars have two components , with peaks ( in the usual @xmath1 representation ) separated by @xmath2 decades in frequency , as discussed by @xcite and several authors in this volume . the lower frequency component has peak frequency , @xmath3 , in the ir - x - ray energy range , and is generally believed to be due to synchrotron radiation , so the peak can be identified with a characteristic electron energy @xmath4 . typically blazars are more variable more rapidly and with larger amplitude at or above the spectral peak , certainly in the synchrotron component and plausibly in the gamma - ray component , although here the data are much more sparse . the variability in the two blazar spectral components is correlated , with wavelength - dependent lags , between approximately corresponding points on the two curves ( @xcite ) . this has led to the suggestion that a single population of electrons could be responsible for the bulk of the emission in both components , via synchrotron radiation in the low energy bump and via compton scattering of local soft photons in the high energy bump . ( other components contribute to the extended radio emission and to an optical / uv bump , if present . ) for the remainder of the talk , i refer to `` synchrotron '' and `` compton '' spectral components , but recognize that for the high - energy emission at least , there are other still - plausible models . as others discuss at this conference , the origin of the seed photons for the compton - scattered gamma - rays has been a subject of some speculation . different possibilities include local synchrotron photons produced by the same electron population ( the ssc model , @xcite ) , or sources external to the jet , such as accretion disk photons ( @xcite ) or reprocessed photons from the broad - line region ( @xcite ) . quite possibly the relative importance of these possibilities changes from one source to the next , or between active and quiescent periods in a given source , as the intrinsic source properties change ( @xcite ) . there are clues in the trends in blazar properties with luminosity . rita sambruna showed in her ph.d . thesis that synchrotron peak frequencies and overall spectral shapes differed among x - ray - selected bl lac objects , radio - selected bl lac objects , and flat - spectrum radio quasars ( @xcite ) , in a way that could not be explained simply by beaming . instead , the seds changed shape systematically with luminosity , such that high luminosity bl lac objects and quasars have synchrotron peaks in the ir - optical , while lower luminosity bl lacs peak at higher energies , typically uv - x - ray . we refer to these as lbl ( for low - frequency peaked blazars ) and hbl ( for high - frequency peaked blazars ) , respectively ( see @xcite for exact definition ) , or more descriptively , as `` red '' and `` blue '' blazars . bl lacs found in the first x - ray surveys were generally hbl / blue ; bl lacs found in classical radio surveys were generally lbl / red , as were most fsrq ( flat - spectrum radio - loud quasars ) , though `` bluer '' fsrq are now being identified in multiwavelength surveys designed not to exclude them ( @xcite ) . cc as @xmath5 increases , & @xmath6 decreases + & @xmath7 increases + & @xmath8 increases + + taking a synthetic view of the origin of the seds , it seems the bright egret blazars , which have peak gamma - ray emission near @xmath9 gev , are much like the few known tev blazars , which peak @xmath10 times higher in energy . this is important because many more `` gev '' blazars are known and have been studied than `` tev '' blazars . with appropriate scaling , we should be able to use the observed behavior of the gev blazars ( see @xcite ) to inform our multiwavelength studies of tev blazars ( discussed below and see @xcite ) . the sed trends support a simple paradigm ( @xcite ) in which electrons in higher luminosity blazars suffer more cooling because of larger external photon densities in the jet ( as indicated by the higher @xmath8 characteristic of this group ) . this leads naturally to lower characteristic electron energies , as well as larger ratios of inverse compton to synchrotron luminosity ( @xmath11 ) because of the `` external compton '' ( ec ) contribution . in contrast , lower luminosity blazars are dominated by ( weaker ) ssc cooling , and so have electrons with higher @xmath12 . the correlation of @xmath12 with energy density may even suggest that electron acceleration in blazars is independent of luminosity , and that only the cooling differs ( @xcite ) . a similar luminosity - linked scheme , with a somewhat more physical motivation , was developed by markos georganopoulos in his ph.d . thesis ( @xcite ) . in any case , the current view is that the ec process dominates the gamma - ray production in high - luminosity blazars , while the ssc process dominates in low - luminosity blazars . the x - rays from either high- or low - luminosity blazars are likely dominated by ssc ( @xcite ) . the similarity of @xmath13 in hbl and fsrq / lbl is somewhat puzzling in this picture , and will be physically important if it persists when ( if ? ) further tev observations define the hbl compton peaks well ( this is complicated by the effect of the klein - nishina cross section at tev energies ) . in a simple homogeneous ssc model , @xmath14 , whereas in the simplest ec models @xmath15 , where @xmath16 is the characteristic frequency of the external seed photons . if @xmath13 changes little from ssc - dominated to ec - dominated blazars , then perhaps energy is distributed so that the typical electron energy , which depends on acceleration , cooling , and escape , maintains the appropriate relation to the magnetic field energy density . two caveats to this scheme bear mentioning , as both can lead to higher _ observed _ @xmath11 in high - luminosity blazars , even when there are no significant intrinsic differences . first , dermer has pointed out that ec gamma - rays are more tightly beamed than ssc . therefore , if the ec process dominates the gamma - ray emission in high - luminosity blazars but the ssc process dominates in low - luminosity blazars , the increase of @xmath11 with luminosity will be exaggerated ( and could even be spurious ) . second is a sort of `` variability bias '' ( see @xcite ) . given the limited sensitivity of egret , which typically had to integrate for one or more weeks to detect a blazar , this bias arises if two plausible assumptions hold : ( 1 ) high - luminosity sources are larger than low - luminosity sources , and their intrinsic variability time scales are proportionately longer , and ( 2 ) blazar gamma - ray light curves are characterized by flares separated by quiescent periods , as suggested by the long - term egret light curve of 3c 279 ( @xcite ) . scaling from 3c 279 , even as slowly as @xmath17 , a typical egret observation would span several flares in a low - luminosity blazar , sampling an average flux close to the quiescent value , hence implying a weak gamma - ray source . in contrast , a high - luminosity source like 3c 279 would be observed either during a flare , in which case it would appear quite luminous , or else tend to be undetected . indeed , many bright lbls have never been detected with egret . ( note that high - luminosity blazars have a higher average redshift than low - luminosity blazars , due to their lower space density , and so are less likely to be close enough to detect during quiescent periods . ) the net effect of measuring systematically much - higher - than - average gamma - ray luminosities in high - luminosity blazars , and roughly - average - quiescent gamma - ray luminosities in low - luminosity blazars , is to produce the observed trend of @xmath11 with @xmath18 , at least qualitatively . in the well - known multi - epoch sed of 3c 279 ( e.g. , @xcite ) , this is seen explicitly : during the highest state , the compton ratio is between 10 and 100 , while during the lowest state , it is 1 or perhaps less ( it is poorly determined because the synchrotron peak for this source is in the far - ir and was seldom observed in the key multiwavelength campaigns ) . thus both biases , the greater beaming for ec compared to ssc , and the tendency to detect single flares versus multiple flares depending on luminosity , lead in the same direction , toward higher compton ratios in high - luminosity sources . whether these biases can explain the observed trend quantitatively is not yet clear , but they need to be evaluated in within the context of any blazar paradigm ( necessarily in a model - dependent way ) . what then are the general properties of the tev - bright blazars ? so far , only two , mkn 421 and mkn 501 , have been studied in detail , and few additional sources have been reported ( 1es 2344 + 514 , @xcite ; pks 2155304 , @xcite ; 1es 1959 + 050 , @xcite ) . with only two sources reported more than once in the literature , we know little about tev blazars as a class . the seds of the two well - studied tev - bright blazars have the usual shape for blue blazars . for mkn 421 , the synchrotron peak is at or slightly above 10@xmath19 hz , and the compton peak ( including the effect of the klein - nishina cross section , which suppresses the compton component at lower frequencies than would be the case in the thomson limit ) occurs just below 1 tev . the observed compton ratio is @xmath20 ( @xcite ) . mkn 501 is slightly different , with a typically lower compton ratio , although this impression is strongly influenced by the bright flare in spring 1997 , when the synchrotron peak increased to @xmath21 kev ( @xcite ) . note that , as @xcite shows so clearly , the tev emission comes largely from low - energy electrons scattering low - energy photons ( below the synchrotron peak ) , with high - energy electrons ( those with @xmath22 ) contributing to a hard tail above the compton peak . this means the tev emission reflects closely the electron spectrum and variability , and is relatively insensitive to changes in the seed photon flux ( which changes slowly at frequencies below the synchrotron peak ; @xcite ) . following the general paradigm , we expect blazars with high - energy synchrotron peaks , the hbl / blue blazars , to be bright at tev energies . accordingly , we undertook a survey with hegra of likely tev candidates ( with ron remillard and felix aharonian ) , starting from a list of x - ray - peaked , x - ray - bright , nearby bl lacs . ( a few lbl , typically well - known bl lacs , were also observed . ) because these sources are x - ray bright , they are detectable with the rxte all sky monitor ( asm ) , at least in their higher states . if these objects are like mkn 421 , then the 2 - 10 kev x - ray emission is near the peak synchrotron output and the tev emission is near the peak compton output ; thus , the hegra measurements are a probe of the compton ratio . our goal was to measure this ratio , or a limit to it , for blazars generally . in the end , we observed 10 sources , including 7 hbl and 3 lbl . none were detected and there are only upper limits for the tev flux ( @xcite ) . because hegra sensitivity is @xmath23 ergs @xmath24 s@xmath25 and asm sensitivity is @xmath26 ergs @xmath24 s@xmath25 , we can in principle , using simultaneous asm observations , probe an interesting regime in compton ratio , as low as @xmath27 . unfortunately , six of the sources were also below the asm detection limit at the epoch of the hegra observations , thus we have only four estimates of the compton ratio , from 3 hbl and 1 lbl ( see fig . [ fig : limits ] ) . the best estimates of the ratios all lie well below 1 , closer to 0.1 or 0.2 . the 95% confidence upper limits range from 0.35 down to 0.18 . either the typical ratios in blazars are below 1 , or the spectra of these four objects differ from mkn 421 . specifically , if the 2 - 10 kev asm band is near the peak of the synchrotron component but the 1 - 10 tev hegra band lies above the peak of the compton component , then the measured limit underestimates the compton ratio . from this limited survey we infer that the typical compton ratios of tev - bright blazars may be closer to @xmath28 than @xmath9 . this implies different source parameters than for mkn 421 , for which @xmath11 is usually @xmath9 . for example , @xcite derived constraints on the magnetic field and the doppler factor of mkn 421 in the context of a simple homogeneous emitting volume . if the value of @xmath11 is lower by a factor of @xmath0 , the magnetic field and/or the doppler factor must be higher by a factor of a few . our tev survey was limited not by the lack of hegra detections but by the lack of simultaneous x - ray detections ( the asm is a factor of a few less sensitive than required ) . in the future , in order to estimate the compton ratio in an unbiased way , the most fruitful approach would be to dedicate pointed rxte or sax or asca observations to a well - chosen hbl sample , observing simultaneously in the tev . x - ray detection would be assured , so that any tev limit would be significant , and the x - ray spectra would allow determination of the synchrotron peak , so the tev limits could be interpreted with less ambiguity . alternatively , to improve the chances of a tev detection , one could make the plausible link between x - ray flaring and tev flaring , as observed explicitly in mkn 421 and mkn 501 , and thus try to trigger on x - ray flares . from the asm data ( http://space.mit.edu/xte/asm_lc.html ) it is clear that many blazars have relatively short - lived high states . thus one would need to trigger with very little delay , perhaps responding within 1 day to asm detections of bright states . with the automated state of data processing in the asm , such rapid notification to tev observers should be routinely possible . since mkn 421 is a very bright source at x - ray and tev energies , it is an obvious target for monitoring , even recognizing that the results are likely biased toward the flaring state . when rxte asm data indicated that mkn 421 was flaring in february 1997 , we triggered a target of opportunity ( too ) , observing roughly every 10 days with the rxte pca through july 1998 , with a few additional observations in august 1998 . daily less - sensitive x - ray observations are available from the asm . during much of this time hegra ( and other tev telescopes ) were also observing , except during bright time . figure [ fig:421lc ] shows the x - ray and tev light curves . in the x - ray , the pca ( filled circles ) detects short time scale variability , while the light curve of daily asm averages ( open circles ) samples the longer time scale variability ; the two agree well . in early june 1998 ( around mjd 50970 ) , the pca light curve shows a steep decline in x - ray flux , by more than a factor of 2 in 5 hours . the tev and x - ray fluxes appear well correlated , consistent with the zero lag ( within 1 day ) found from more extensive x - ray and tev light curves of mkn 421 ( @xcite ) . with additional tev data from the june 1998 flare , it should be possible to comment on lags at shorter time scales . this is certainly in accord with the blazar paradigm discussed above , where a single electron population produces the x - rays via synchrotron radiation and the tev emission via compton scattering of soft photons ( probably low - frequency synchrotron radiation ) . only a handful of blazars have been well - monitored simultaneously in multiple spectral bands , the gev - bright blazar 3c 279 and a few others , and the tev - bright blazars mkn 421 and pks 2155304 . while mkn 421 has also been monitored at tev energies ( and presumably pks 2155304 will be as well now that southern cerenkov telescopes are coming on line ) , pks 2155304 has probably the best simultaneous data at optical through x - ray energies , which is to say at the high energy end of the synchrotron component . there have been four extensive multiwavelength campaigns to observe pks 2155304 with multiple satellites . in november 1991 ( @xcite ) , rosat ( soft x - ray ) and iue ( uv and optical ) light curves showed closely correlated variations of modest , wavelength - independent amplitude ( @xmath29% ) , with the x - rays leading the uv by a few hours . a second campaign in may 1994 using asca , rosat , euve , iue ( without the optical data ) , and ground - based telescopes showed altogether different results : a strong isolated flare in each band , with much larger amplitude at shorter wavelengths , and with 1-day delays between x - ray and euv , and between euv and uv wavelengths ( @xcite ) . while such disparate behavior might intuitively suggest quite different properties in the emitting plasma , in fact , @xcite explain much of the observed multiwavelength behavior starting from the same underlying jet and varying only the electron injection event . a third multiwavelength monitoring campaign in may 1996 , involving rxte , rosat , and euve ( and lacking iue because of a spacecraft failure a few weeks earlier ) shows yet another result ( @xcite ) , shown in figure [ fig:2155lc ] . the rxte pca and rosat pspc light curves are well correlated in the second half of the 12-day observation , with little or no lag , but near the beginning , a large flare in the rxte data is not seen in the rosat data ( although there is a small gap in the rosat data ) . a fourth campaign , in november 1996 , with rxte and rosat , again shows good correlation as far as the more limited data allow ( @xcite ) . these disparate results illustrate the danger of drawing strong conclusions from single - epoch multiwavelength campaigns , not to mention the danger of extrapolating from one or two sources to all blazars . others have referred to the extraordinary flaring of mkn 501 in april 1997 , with strong tev flux and x - ray spectrum hardening in a previously unobserved way ( @xcite ) . pian and collaborators observed mkn 501 again with bepposax in april 1998 , and found that while the x - ray flux remained quite high and was similar to that seen in april 1997 , the synchrotron peak was at @xmath0 - 20 kev , still harder than typical but a factor of @xmath0 lower in energy than at the peak of the 1997 flare ( @xcite ) . thus the characteristic electron energy is somewhat lower but there is clearly ongoing acceleration , sustained over more than one year , as evidenced by the continuous rxte asm light curves . apparently the time scales in mkn 501 are longer than in mkn 421 , at least at the present epoch , despite their similar luminosities and spectral properties . we have described how the spectral energy distributions of blazars differ markedly between the low - luminosity sources discovered primarily in x - ray surveys and the high - luminosity sources discovered primarily in radio surveys . whether the origin of the sed differences is due to electron cooling or something else , inevitably the jet physics in the two types of blazar must differ . in fact , given the selection biases , there must be a distribution of seds , and therefore a range of typical electron energies and/or jet physics , as indeed has been found recently in surveys selected to favor intermediate objects ( @xcite ) . clearly nature makes jets with a range of properties . perhaps the process of jet formation varies , or the effect of circumnuclear environment affects the eventual jet properties , or some combination of the two ( e.g. , @xcite ) . since jet formation is a fundamental question , it is of considerable interest to understand the imf , as it were , of jets . in fact , the relative number of red blazars and blue blazars is very poorly known ( @xcite ) . x - ray surveys , which find the blue blazars because of their high - frequency synchrotron peaks , span a large range in flux but a relatively small range in luminosity . radio surveys , which pick out red blazars because of their low - frequency peaks , span a small range in flux but a rather larger range in luminosity . both are undoubtedly biased , but to find the absolute numbers of blue or red blazars requires correcting either type of survey for the kind of objects not found in that survey . deriving the relative density of types of blazars is inevitably a model - dependent process . figure [ fig : counts ] illustrates the dilemma with two extreme cases . if one assumes that x - ray surveys are unbiased , then the numbers of x - ray sources is reflected in the source counts , here taken from a number of surveys at different flux limits ( left panel ) . to compare the density of red blazars , we convert the radio counts to x - ray counts via the average value of @xmath30 appropriate to this sample ( @xcite ) , and plot these also in the left panel of figure [ fig : counts ] . the values of @xmath30 are quite steep ( the x - ray fluxes are low ) so the radio counts lie on the low - flux left side of the plot . this representation of the source counts suggests red blazars are 10 times less numerous than blue blazars . this is certainly the case for a given x - ray flux but would be true in a bolometric sense only if the seds of red and blue blazars were the same , which we know very well they are not . alternatively , one can assume the radio survey is unbiased , and compare surface densities of red and blue blazars starting from the 1 jy and s4 surveys . in this case , the x - ray samples are converted to radio fluxes using the average @xmath30 appropriate to this sample ( quite flat , so leading to low radio fluxes ) . here the flux ranges do not overlap at all , but using the extrapolation implied by the best - fit beaming model ( @xcite ; solid line in both panels ) , we would conclude that the radio - selected red blazars are 10 times less numerous than the x - ray - selected blue blazars . the truth probably lies between these two extreme views , but at present it is not constrained . this has of course been explored in much greater detail , starting from luminosity functions that agree with observation , making some assumptions , and calculating absolute numbers ( @xcite ) . we can say that the simple picture wherein blue blazars are seen at larger angles to the line of sight than red blazars , on average ( @xcite ) does not explain the full range of seds ( cf . @xcite ) , and thus the implication that blue blazars are more numerous ( due to their larger solid angle ) does not seem to be correct . on the other hand , the assumption that the radio is unbiased ( @xcite ) and that there is a distribution of spectral cutoffs does explain the observed x - ray and radio counts , but the calculation is entirely symmetric with respect to wavelength . one can equally well assume that the x - ray is unbiased , and that there is a range of spectral cutoffs toward longer wavelengths , and again the x - ray and radio counts can be matched . this ambiguity results because present samples are small and , particularly in the radio , have relatively high flux limits . even slightly more sensitive radio surveys should be able to verify or disprove these two contradictory hypotheses . a viable blazar paradigm can be constructed from the observed multiwavelength properties of blazars . all blazars would have synchrotron and inverse - compton - scattered components , with external seed photons dominating the gamma - ray component in high - luminosity sources ( the ec model ) and synchrotron seed photons dominating in low - luminosity sources ( the ssc model ) . in both cases , the x - rays are likely to be dominated by compton - scattered synchrotron ( ssc ) photons . empirical relations between source parameters and luminosity suggest electron acceleration may be universally the same independent of luminosity , whereas cooling is strongly luminosity - dependent . the more luminous sources , with their high ambient photon densities , have much greater cooling and therefore lower average electron energies , and therefore lower frequency synchrotron and compton peaks , as well as higher ratios of compton to synchrotron radiation . several selection effects could exaggerate this trend , however . the multiwavelength properties of tev - bright blazars are beginning to be well studied . however , the average properties of blue blazars may be different from those of the well - studied tev blazars mkn 421 and mkn 501 . for example , a small survey with hegra suggests the typical compton ratio may be closer to @xmath28 than 1 . further tev observations , combined with more sensitive simultaneous x - ray observations , are needed to confirm this suggestion . in addition , x - ray monitoring can be used to pick out flaring blazars as potentially strong tev sources ; however the trigger times needed are quite short , less than 1 day . certainly in mkn 421 and mkn 501 , the tev and x - ray light curves are well correlated , with delays @xmath31 day . pks 2155304 , perhaps the best observed blazar at uv - x wavelengths , illustrates the complexity of blazar variability and the danger of strong conclusions from limited data sets . mkn 501 continues to be in a high state but @xmath12 has decreased , judging from synchrotron peak frequency , which is a factor of @xmath0 lower than one year earlier . finally , jet demographics are an interesting and not yet well understood issue . whether nature forms more high - luminosity jets than low - luminosity jets , as implied if red blazars are more numerous , or the opposite , is unclear and is of fundamental physical significance . this problem can be approached with deeper samples of flat - spectrum radio sources . acknowledgements it is a pleasure to thank my blazar colleagues , particularly those with whom i have worked most closely in the past year , riccardo scarpa , rita sambruna , ron remillard , elena pian , laura maraschi , gabriele ghisellini , giovanni fossati , annalisa celotti , and felix aharonian , and to acknowledge the warm hospitality of the center for astrophysical sciences at the johns hopkins university and the brera observatory of milan during my sabbatical . we thank the hegra collaboration for permission to use the mkn 421 data in advance of publication . this work was supported in part by nasa grants nag5 - 3313 and nag5 - 3138 . urry , m. sambruna , w.p . brinkmann , h.l . marshall , in _ the active x - ray sky . results from bepposax and rossixte _ , eds . l. scarsi , h. bradt , p. giommi , f. fiore ( amsterdam : elsevier / north holland ) _ nucl . b ( proc . suppl . ) _ * 69,1 - 3 * ( 1998 ) 419 .

blazar spectral energy distributions ( seds ) are double peaked and follow a self - similar sequence in luminosity . the so - called blue " blazars , whose first sed component peaks at x - ray energies , are tev sources , although with a relatively small fraction of their bolometric luminosities . the red " blazars , with sed peaks in the infrared - optical range , appear to emit relatively more power in the gamma - ray component but at much lower energies ( gev and below ) . correlated variations across the seds ( of both types ) are consistent with the picture that a single electron population gives rise to the high - energy parts of both sed components , via synchrotron at low energies and compton - scattering at high energies . in this scenario , the trends of sed shape with luminosity can be explained by electron cooling on ambient photons . with simple assumptions , we can make some estimates of the physical conditions in blazar jets of each type " and can predict which blazars are the most likely tev sources . upper limits from a mini - survey of candidate tev sources indicate that only @xmath0% of their bolometric luminosity is radiated in gamma - rays , assuming the two sed components peak near 1 kev and 1 tev . finally , present blazar samples are too shallow to indicate what kinds of jets nature prefers , i.e. , whether the low - luminosity blue " blazars or the high - luminosity red " blazars are more common . blazars ; bl lac objects ; multiwavelength spectra

Endoscope Maker Olympus Agrees To $646 Million Settlement Over Kickbacks Enlarge this image toggle caption Kiyoshi Ota/Bloomberg via Getty Images Kiyoshi Ota/Bloomberg via Getty Images Medical device maker Olympus Corp., already under federal investigation for its role in superbug outbreaks, has agreed to pay $646 million to resolve criminal and civil probes into illegal kickbacks and bribes to doctors and hospitals. Federal prosecutors said Tuesday that the company's settlement is the largest ever for violations of the U.S. Anti-Kickback Statute. A portion of the company's payout, $22.8 million, will resolve similar bribery allegations in Latin America. U.S. investigators said the Tokyo-based company's "greed-fueled kickback scheme" from 2006 to 2011 used research grants, consulting deals, luxury trips, gifts of hot-air ballooning and spa treatments and free equipment to induce influential doctors to order more Olympus devices at prominent hospitals and help the company keep out competitors. The devices included gastrointestinal scopes, which have been tied to deadly outbreaks of drug-resistant bacteria. In one case, according to the federal criminal complaint, senior Olympus executives agreed to pay for three doctors to spend a week in Japan "as a quid pro quo" for a prominent California institution to switch from a competitor's products to Olympus. After the trip, one of the doctors thanked Olympus for "providing so much extra entertainment that we did not expect," according to the government's complaint. Prosecutors declined to name any medical centers or doctors in their complaint. In other instance, Olympus gave a doctor $400,000 worth of free endoscopes and other supplies for his private practice from 2006 to 2010, prosecutors said. Olympus believed this doctor could persuade a "leading New York medical center" to spend millions of dollars on devices, according to the government complaint. This strategy appeared to pay off for Olympus. Prosecutors alleged that after a key doctor for a Midwest hospital system took a week-long trip to Japan and received a company grant, an Olympus vice president wrote an internal email in 2006 that said, "We have received all of the orders expected and have kept [a competitor] completely out of the [hospital] system. Hooray!" As part of the settlement, Olympus agreed to a corporate-integrity agreement and the appointment of an independent monitor, Larry Mackey, a former prosecutor in the Oklahoma City bombing cases. "Olympus leadership acknowledges the company's responsibility for the past conduct, which does not represent the values of Olympus or its employees," Nacho Abia, chief executive of the Olympus Corp. of the Americas unit in Center Valley, Pa., said in a statement. "Olympus is committed to complying with all laws and regulations and to adhering to our own rigorous code of conduct." As a result of the kickbacks, Olympus generated more than $600 million in sales and reaped gross profits of $230 million, officials said. Olympus is the leading manufacturer of gastrointestinal scopes worldwide, and it boasts an 85 percent share of the U.S. market. "Kickbacks are illegal because they taint buying decisions," said Paul Fishman, U.S. Attorney for the District of New Jersey, which spearheaded the investigation. "Doctors and hospitals should decide to purchase medical devices based solely on legitimate considerations, like quality and price. They shouldn't be tempted and swayed by free trips, free equipment, consulting agreements or research grant money." Prosecutors credited the help of the former chief compliance officer at Olympus, John Slowik, who filed a whistleblower case against the company under seal in 2010. In his whistleblower complaint, unsealed Tuesday after the government's announcement, he said he was fired by Olympus for trying to end improper practices. Slowik now stands to receive about $50 million from the settlement, in accordance with federal whistleblower law, prosecutors said. Patrick Burns, acting president of the Taxpayers Against Fraud Education Fund, praised Slowik, saying he exposed illegal actions that wasted money and threatened patient safety. "This is exactly why we need whistleblowers — because companies cannot be relied upon to put patients before profits," Burns said. Olympus was "funding a massive kickback scheme that channeled millions of dollars in payola to doctors and hospitals." Well before Tuesday's announcement, Olympus was under fire for failing to alert U.S. regulators and hospitals sooner about the risks of infection from its duodenoscopes, a gastrointestinal scope that has proven difficult to clean of dangerous bacteria because of its intricate design. A Senate investigation released in January identified 19 scope-related outbreaks at U.S. medical centers from 2012 to 2015 that sickened nearly 200 patients with drug-resistant infections. Thirteen of those outbreaks were associated with Olympus scopes. Olympus announced in January it would recall its duodenoscopes nationwide and make repairs to better protect patients. Last year, the company disclosed it had received a subpoena from federal prosecutors seeking "information relating to duodenoscopes." In the kickback case, federal officials said Olympus used a grants committee staffed by sales and marketing executives to dole out millions of dollars to key hospital and physician customers. In 2007, Fishman said an Olympus vice president recommended a research grant of $100,000 to a hospital's foundation. "Why? Because that hospital was their '#1 account in the US' and they had, and I'm quoting, 'no intention of losing it' to a competitor," Fishman said Tuesday. Although prosecutors didn't identify institutions, the whistleblower's complaint did mention some physicians and hospitals by name. For instance, it recounted an October 2009 meeting between top Olympus executives and a prominent doctor at the University of Southern California's Keck School of Medicine, about the possibility of a company grant. After the meeting, an Olympus executive in Japan emailed a counterpart in the U.S. about his opinion on the USC grant in light of "future business expansion (any future sales potential?)," according to the whistleblower's complaint. A spokeswoman for USC said she couldn't immediately comment late Tuesday. Olympus reported a general payment of $64,013 to USC's Keck Hospital in 2014 for "in-kind items and services," according to federal data on industry contributions to doctors and teaching hospitals. Overall, for 2014, Olympus issued $5.25 million in general and research-related payments to physicians and hospitals, the federal database shows. Slowik, the whistleblower, said the company ran a "sham physician consultant program" that paid some doctors more than $100,000 annually. Prosecutors said Olympus paid one doctor $112,300 for consulting from 2006 to 2011 in order to influence the purchasing decisions of a "leading Southeastern medical institution." The company also used "permanent loans" or "medical loaner scopes" to improperly give hospitals free equipment, inducing them to buy more products, according to federal investigators. "This practice enabled Olympus America to acquire monopoly power in certain segments of the medical business, ultimately resulting in customers paying inflated prices," according to Slowik's amended complaint. This story was produced by Kaiser Health News, which publishes California Healthline, a service of the California Health Care Foundation. ||||| Breaking News Emails Get breaking news alerts and special reports. The news and stories that matter, delivered weekday mornings. March 1, 2016, 9:15 PM GMT / Updated March 1, 2016, 9:15 PM GMT By Tracy Connor A corporate whistleblower is set to collect $51 million — his share of a massive settlement with Olympus America to resolve charges it gave doctors and hospitals kickbacks to order its medical equipment. John Slowik worked for the imaging giant for 20 years and served as its compliance officer before he was let go in 2010, according to court papers. In a qui tam whistleblower suit, he alleged that the company ignored his efforts to stop it from giving financial rewards to hospitals and physicians for buying Olympus endoscopes, which are used to examine the digestive tract. Doctors and hospital officials got lavish junkets, fancy meals, research grants and free equipment, prosecutors and Slowik alleged. In one case, three doctors got a trip to Japan after their hospital ditched another supplier and switched to Olympus, prosecutors said. Slowik, who declined to be interviewed, claimed in court papers that when he took steps to stop the kickbacks, he was bounced from his compliance job and subjected to "systematic harassment" that made him physically ill. Under the False Claim Acts, whistleblowers who file suit on behalf of the federal government showing that taxpayers are being ripped off are entitled to a percentage of the money recovered. In the settlement announced Tuesday, Olympus will pay $310 million to settle civil claims by the federal government and state, and Slowik gets $51 million — one of the largest whistleblower awards in history. Olympus also agreed to pay $312 million in criminal penalties to avoid prosecution. The total settlement is the largest amount ever paid by a medical device company and the largest for violations of the Anti-Kickback Statute, which covers medical purchases paid for by federal health care programs like Medicare. A spokesman for Olympus said he could not comment on Slowik's suit but noted that it cooperated with a Justice Department probe that began in 2011. “Olympus leadership acknowledges the Company’s responsibility for the past conduct, which does not represent the values of Olympus or its employees," the company said in a statement. "Olympus is committed to complying with all laws and regulations and to adhering to our own rigorous Code of Conduct which guides our business processes, decisions and behavior. The Company has implemented and will continue to enhance its robust compliance program.”

– A whistleblower who worked for Olympus Corporation of the Americas for 20 years will receive $51 million from the company after it admitted to a scheme of bribery and kickbacks and agreed Tuesday to pay $646 million in fines, CNNMoney reports. John Slowik was named the company's compliance officer in 2009, but he soon started registering complaints about doctors and hospital administrators receiving grants, costly trips, and other entertainment—which NPR says included spa treatments and hot air balloon rides—to woo them to buy Olympus' medical equipment. He was fired in 2010 and filed a lawsuit against the company, noting his complaints about the equipment (specifically, endoscopes to check out the digestive tract) fell on deaf ears, NBC News reports. Because he filed the suit on behalf of the federal government, which CNN notes was getting ripped off by the scheme, Slowik is entitled under the False Claims Act to part of any recovered money. Slowik says negative reaction to his complaints came all the way from the top: Per his suit, he says Mark Gumz, who was the Olympus CEO when Slowik was made compliance officer, told him to "try to figure out how to 'work around the rules' so as to 'not impact the business.'" When instead Slowik tried to rein in the bribery and kickbacks he discovered, he says Gumz started to "ostracize and harass" him, to the point where he became physically ill. Such kickbacks and bribes could "improperly influence a provider's judgment about a patient's health care needs, result in the use of inferior or overpriced equipment, and drive up health care costs for everybody," the DoJ's deputy AG says, per CNN. As for the $646 million in total fines Olympus now has to cough up, CNN notes that about half of that is for going against the feds' anti-kickback statute and will be the largest amount ever paid out for violating that law. (A whistleblower recently revealed the "dirtiest secret" in sports.)

the nernst effect in the cuprate superconductors has recently become a focus of attention both experimentally @xcite and theoretically @xcite . the nernst effect is the electric field induced when the sample has a temperature gradient , @xmath1 , perpendicular to the magnetic field , @xmath2 ; this electric field is perpendicular to both @xmath1 and @xmath2 . for some cuprate superconductors the nernst effect due to superconducting fluctuations is detectable at temperatures far above the transition temperature , @xmath3 @xcite . @xcite calculated the low - field nernst effect for @xmath4 due to superconducting fluctuations , obtaining results in reasonable agreement ( in absolute units ) with experimental data . they used the linearized time - dependent ginzburg - landau ( tdgl ) equation , which is identical to the aslamazov - larkin @xcite approximation for the microscopics . linearized ( gaussian ) tdgl is applicable far enough above the mean - field transition temperature @xmath5 , where the order parameter fluctuations are small enough to neglect the nonlinear terms in the full ginzburg - landau free energy . to estimate the nernst effect closer to @xmath3 they also treated the nonlinearities in tdgl in the hartree approximation @xcite . prominent in the phase diagrams of the cuprate superconductors in a magnetic field is the _ vortex liquid regime _ , where short - range superconducting correlations are strong ( because @xmath6 ) , but thermal phase and vortex fluctuations disrupt the superconducting coherence on longer scales . the experimentally observed nernst effect remains large in this regime @xcite , which is not accessible to analytic calculations due to its strong correlations and fluctuations . however , the tdgl equation with its full nonlinearity and driven by thermal fluctuations can be numerically simulated in this vortex liquid regime , and its nernst effect measured and compared to experiments , as we demonstrate below . when the tdgl approximation is used to model properties of cuprate superconductors , for which there is not a well - established more microscopic theory , or more generally when it is used well away from the zero - field critical temperature , as we do here , it constitutes a standard , widely - used , but essentially phenomenological approximation . it has the virtue that most of the parameters that enter can be determined from experiments , as we discuss below . for bcs superconductors , the tdgl approximation can be systematically derived from the microscopics in some limited regimes @xcite , but here we are instead using it more broadly , in regimes where its justification is `` only '' phenomenological . the nernst effect in the vortex liquid can be described in terms of the vortices as the phase - slip voltage due to vortices being transported down the temperature gradient as heat carriers . however , when one calculates the nernst effect at higher temperatures in linearized tdgl @xcite , what is happening is that superconducting order parameter fluctuations are transported along the temperature gradient and their phase patterns are twisted by this motion across the magnetic field , inducing a nernst voltage ; vortices play no role in the calculation . in a tdgl treatment of the vortex liquid regime , there is no clean distinction between order parameter fluctuations and vortex motion , so both of these two different - sounding descriptions are in some sense correct . in this paper , we present the method for and results of simulations of thermoelectric transport in type - ii superconductors in the vortex liquid regime . we simulate the tdgl equation with thermal noise . we work in the strongly type - ii limit , @xmath7 , where the magnetic field in the sample is assumed to be uniform and not fluctuating . mostly we work in two dimensions , but we also examine the crossover from two - dimensional to three - dimensional behavior . in our study of interlayer couplings we see some indication that a substantial part of the entropy carried by the vortices in the vortex liquid may be the configurational entropy of their positions . our simulations involve a dimensionless tunable parameter ( @xmath8 ) which sets the strength of the thermal fluctuations in the sample and hence can range from nearly mean - field behavior with very weak fluctuations to very strong fluctuations with strongly suppressed superconductivity . we show that for an intermediate value of this parameter our results are in reasonably good qualitative and quantitative agreement with available experimental nernst - effect data on overdoped la@xmath9sr@xmath10cuo@xmath11 ( lsco ) @xcite . in this comparison all the other parameters in the simulations are set by experimentally measured quantities . we also discuss in brief the results of our simulations to model experiments on bi@xmath12sr@xmath12cacu@xmath12o@xmath13 ( bscco ) @xcite . we briefly review some of the general theory of thermal and electrical transport coefficients in linear response in the presence of a magnetic field . consider a sample at temperature @xmath14 subjected to small gradients in the potential @xmath15 and temperature @xmath16 . one can then very generally write down the transport current densities in the system to linear order in @xmath15 and @xmath16 as @xmath17 @xmath18 where @xmath19 is the charge transport current density and @xmath20 is the heat transport current density . @xmath21 , @xmath22 , @xmath23 and @xmath24 are the electrical conductivity , thermoelectric , electrothermal and thermal conductivity tensors . the onsager relations for the transport coefficients tell us that @xmath25 . the nernst coefficent ( @xmath26 ) can be defined in a configuration with a magnetic field @xmath27 and @xmath28 along with the condition @xmath29 as @xmath30 if the system shows no hall effect ( like the one we have simulated ) , then @xmath31 and @xmath32 one way to obtain transport coefficients from a simulation is via the kubo relations , thus measuring current - current correlations in the equilibrium dynamics . alternatively , one can apply an electric field and/or a temperature gradient and measure the resulting currents . we have used both methods , finding that our implementation of the latter method gives higher signal - to - noise ratio per unit computer time in the regime we have been studying . the currents flowing in the sample have magnetization parts in addition to the transport parts considered above . one could write down linear response relations for the total current densities analogous to the ones for the transport current densities but the coefficients appearing in those would not obey the onsager relations . the total currents in the system can in general be computed in a straightforward manner but one has to extract the transport parts from these to calculate the transport coefficients . this involves identifying and subtracting out the magnetization currents . the procedure we use to that end in this work is outlined below and is based on the arguments of cooper _ et al . _ @xcite . let @xmath33 and @xmath34 be the total charge and heat current densities ( transport + magnetization ) at any point @xmath35 in the sample . if @xmath36 is the electric potential at @xmath35 , there exists a total energy current @xmath37 such that @xmath38 a similar relation holds between the transport parts of these current densities , @xmath39 the average electric current density @xmath40 and heat current density @xmath41 are given by averaging @xmath42 and @xmath43 over the whole sample . for a two dimensional sample @xmath44 and @xmath45 where @xmath46 is the area of the sample . similar relations also hold for three dimensional samples . from eqns . ( 6 ) and ( 8) , we obtain @xmath47 we know that @xmath48 where @xmath49 and @xmath50 are the charge and energy magnetization current densities . it can be shown on general grounds @xcite that there exist charge and energy magnetization densities @xmath51 and @xmath52 such that @xmath53 the charge magnetization of the system is nothing but the conventional magnetic moment density @xmath54 . if the material surrounding the sample is assumed to be non - magnetic , both @xmath55 and @xmath52 vanish outside the sample . the magnetization currents are mostly at the boundaries because that is where the change in magnetization is the largest . thus we see that @xmath56 from eqns ( 9 ) and ( 12 ) , we obtain @xmath57 it should be noted that there is no heat magnetization density " @xmath58 analogous to @xmath55 and @xmath52 for which the heat magnetization current @xmath59 . a consequence of this is that unlike @xmath60 and @xmath61 , @xmath62 in fact , it can be shown that @xmath63 we measure the transport coefficient @xmath64 by turning on an electric field @xmath65 and a magnetic field @xmath27 and measuring @xmath66 , the @xmath67 component of the average heat transport current density at constant temperature . this is done in a system with mixed boundary conditions : it has free surfaces at the boundaries normal to @xmath68 , while it has periodic boundary conditions along the @xmath67-direction ( and along @xmath69 when we study 3d ) . if , as in our model , the system does not have a hall response , under these conditions the @xmath67 component of the electric transport current vanishes at all points , @xmath70 . thus from eqns . ( 2 ) and ( 13 ) , we obtain @xmath71 similarly , @xmath0 can be measured by introducing a temperature gradient @xmath72 and magnetic field @xmath27 with no external electric potential and measuring @xmath73 . from eqns . ( 1 ) and ( 12 ) , @xmath74 the two coefficients @xmath64 are @xmath0 can thus be obtained by measuring only the total currents in the system . they are related to each other by the onsager relation and to the nernst coefficient by eqn . the tdgl equation that we have simulated is @xmath75 we take @xmath76 to be real so there is neither hall effect nor seebeck effect @xcite . this approximation of leaving out the hall effect should be reasonable as long as the hall angle is small , as it generally is in the vortex liquid regime of the cuprate superconductors . we work in the type - ii limit where the magnetic field is assumed to be uniform and not fluctuating . the noise correlator is @xmath77 the current operators we need are @xcite @xmath78 the tdgl equation is the simplest dynamical stochastic equation one can obtain from the ginzburg - landau free energy functional . as a consequence of its simple relaxational dynamics , it does not explicitly conserve either total charge or total energy . it is implicitly in contact with and exchanging energy and charge with local reservoirs . in reality these reservoirs are presumably the phonons , quasiparticles and other excitations not included in the tdgl equation . nevertheless , the charge and energy currents carried by the superconducting order parameter @xmath79 and its fluctuations are as given above and can be measured and their transport properties determined within this model . charge and energy conservation can explicitly be taken into account in microscopic derivations of the tdgl theory , where only the contribution due to superconducting fluctuations is retained . it can however be shown that other effects ( normal state contributions etc . ) do not contribute as significantly to the nernst effect as superconducting fluctuations @xcite . an important feature of tdgl for the present work is that the parameter @xmath76 , which sets the time scale , does not enter in the values of the transverse thermoelectric coefficients that we are studying , @xmath0 and @xmath80 . this allows quantitative comparison to experiments to be done without estimating @xmath76 , which is fortunate , because the value of @xmath76 is quite uncertain . this tdgl equation with noise has a dimensionless parameter that gives the strength of the thermal fluctuations . to remove all the dimensional quantities , we use @xmath81 , the zero temperature coherence length , as our unit of length ; @xmath5 , @xmath82 , @xmath83 and @xmath84 as our units of temperature , energy , magnetic flux and time , respectively ; and @xmath85 , the zero - temperature order parameter magnitude , as our unit for the order parameter . the resulting tdgl equation is then @xmath86 with noise correlator @xmath87 and @xmath88 is the fluctuation parameter , where @xmath89 is the number of spatial dimensions . when @xmath90 , the actual critical temperature @xmath3 is near the mean - field critical temperature @xmath91 , while if @xmath92 then @xmath93 . the model has four parameters that remain after scaling to the units specified above : the temperature , the magnetic field , the cutoff , and the strength @xmath8 of the noise . we initially simulate a two - dimensional system , thus ignoring interlayer coupling . we discretize space and time . the spatial grid spacing is taken to be @xmath81 . this rather coarse spatial grid is used to minimize the computer time needed to simulate samples large compared to this microscopic length . there are noticeable quantitative effects of using such a coarse grid . for example , in our units @xmath94 with this grid , while it is 1.0 for the continuum model . however , recognizing that the model we are simulating is rather simple , so should not be expected to give highly precise quantitative results , our goal in the present study is to be quantitatively only as accurate as might be expected of such a simple model . although we do not know how accurate that really is , the general precision to which we have chosen to work is roughly 10% to 20% . the quantitative shifts due to our using a coarse grid in the simulations are at most of this magnitude . we have also verified that using a finer grid spacing would not alter our results in any significant way . reduction of the grid spacing adds more degrees of freedom , resulting in increased fluctuations , and suppression of @xmath3 and @xmath95 . however , if one also lowers the value of the fluctuation parameter @xmath8 a little , this increase in the fluctuations can be removed , and the resulting behavior of the system is only weakly dependent on the grid spacing . in the simulations , the time step is chosen to be between 0.02 and 0.1 in our units , with shorter steps at higher temperatures ; we check that our results are not affected by doubling the time step . a first - order euler method is used , with 10000 to 20000 time steps used for equilibration , and 30000 to 50000 steps for averaging . the two - dimensional data we show are for a 50@xmath9650 square grid . we use the gauge - invariance of the tdgl equation to work as much as possible in terms of gauge - invariant quantities like @xmath97 and the gauge - invariant phase differences @xmath98 where @xmath99 . the current densities are also written in terms of these quantities . at @xmath100 , for the two - dimensional system there is a kosterlitz - thouless @xcite transition at @xmath3 , which we locate by measuring the helicity modulus . to obtain @xmath64 , we measure the transverse energy current due an electric field . we then use the onsager relation to obtain @xmath101 . we find that the signal to noise ratio for this measurement is significantly smaller than in a direct measurement of @xmath0 . we have numerically verified the validity of this onsager relation by measuring @xmath0 both ways . this also serves as a check that we are indeed measuring the proper transport coefficients . we also confirm that our results agree with the analytic results @xcite in the higher - temperature regime where linearized tdgl applies . the temperature enters the tdgl equation both in the term linear in the order parameter and in the intensity of the noise . it can be shown that introducing a gradient in the linear term only adds to the magnetization currents , and thus for measuring the transport currents it is sufficient to include the temperature gradient only in the noise term . we have also verified this numerically . some results for @xmath0 from the two - dimensional simulations are shown in fig . 1 . we have chosen to compare these results to the experimental results of wang _ et al . _ @xcite obtained from nernst and resistivity measurements on an overdoped lsco sample with @xmath102 and @xmath103k . for this comparison , we present the simulation results in si units using the parameters from the experiment , @xmath104 t ( thus @xmath105 ) and layer spacing @xmath106 . the fluctuation parameter has been adjusted to @xmath107 to give reasonable quantitative agreement between simulation and experiment . we set the temperature scale using @xmath108k , which gives @xmath103k in the simulation . note that @xmath0 is not directly measured in the experiments . for a system with negligible hall effect , @xmath0 can be obtained from the measured nernst effect and the longitudinal resistivity . thus for this comparison we require both these measurements to be made on the same sample over a substantial portion of the vortex liquid regime . this requirement seriously limits the number of experimental results we can compare to . looking at fig . 1 , we see that there is reasonably good general qualitative and quantitative correspondence between the simulation and experiment , considering how simple the model is and that we have adjusted only the strength of the thermal fluctuations @xmath8 to get this agreement . the other parameters are all dictated by experiment . our results are thus consistent with the proposition that the superconducting fluctuations modelled by the tdgl equation produce most , if not all , of the contributions to the large nernst effect seen in the vortex liquid regime for this cuprate sample . of course , the agreement between experiment and this simple model is not perfect . one difference is seen at high field in the higher-@xmath14 panel of fig . 1 , where the simulations give a nearly - constant @xmath0 , while the experiment shows more variation . one effect that is not included in our two - dimensional simulations is interlayer coupling . for the cuprates , this can become important in the vortex liquid at low fields in the vicinity of @xmath3 , where there is a crossover to three - dimensional behavior as the correlation length normal to the layers becomes larger than one layer spacing . note that the difference between simulation and experiment is large at low fields and @xmath110k . we considered the possibility that this difference might be due to the crossover to three - dimensional behavior , which is not present in our two - dimensional simulation . to investigate this crossover , we have also simulated the lawrence - doniach @xcite version of the tdgl equation . in our units this is where @xmath112 is the interlayer josephson coupling per unit area , and @xmath113 is the layer index . the transition temperature is located by finding the intersections of the fourth - order cumulant ( binder ratio ) curves @xmath114 for different system sizes as functions of temperature at zero magnetic field . 2 shows results for @xmath0 as a function of field for various values of interlayer coupling @xmath112 at temperature @xmath115k , from samples of size 15@xmath9615@xmath9610 layers . for each @xmath112 we set the the temperature scale ( @xmath91 ) so that @xmath116k as in the experiment . the values of the other parameters in the simulations are as used in fig . 1 . as expected , the the largest value of @xmath112 shows the largest deviation from the two - dimensional behavior . somewhat better correspondence between the behavior of @xmath0 obtained in simulation and experiment is obtained by adding this interlayer coupling . an interesting point to note in fig . 2 is that at low fields a rather small interlayer coupling @xmath112 produces a strong decrease in @xmath0 . describing this in terms of vortices , as seems appropriate in this low - field regime below @xmath3 , the force per unit length on a vortex line due to the temperature gradient is proportional to @xmath0 . naively , this force is also set by the entropy per unit length transported by a moving vortex . this transport entropy may come from internal degrees of freedom within one vortex , or it may come from the configurational entropy of the many possible spatial arrangements of the vortices . the latter does not involve internal excitations within the vortices . in the quasi - two - dimensional layered superconductors that we are modelling , a vortex line running normal to the layers consists of pancake vortices " in each layer . a weak interlayer coupling has little effect on the internal properties of a single pancake vortex , but it does produce an attraction between vortices in adjacent layers that reduces their relative motion , and thus can substantially reduce the configurational entropy of the vortices . the fact that at low fields a weak interlayer coupling greatly reduces the transport entropy of the vortices , as indicated by the reduction of @xmath0 seen in fig.2 , thus suggests that in this regime the configurational entropy of the vortices is a large part of their transport entropy , at least within this layered tdgl model . we have also performed simulations to model the bscco sample studied by ri _ _ @xcite . the experimental data and the results of the simulation are shown in fig . 3 . the quantity plotted is the measured `` transport energy '' of the vortices , defined as @xmath117 . we used a two - dimensional simulation with @xmath118 k , @xmath119 t , @xmath120 and @xmath121 . again , there is reasonable quantitative agreement , in absolute units , between the experimental data and the simulations . the clearest deviation here occurs for @xmath122k and @xmath123 t , in conclusion , we have measured the transverse thermoelectric transport coefficient @xmath0 in simulations of the vortex - liquid regime of superconductors modeled by the tdgl equation with thermal fluctuations . we find that our simulations of a two - dimensional superconductor reproduce reasonably well much of the qualitative and quantitative features of available experimental data from some cuprate high - temperature superconductors . we have also studied the crossover from two - dimensional to three - dimensional behavior in a layered superconductor . this crossover study indicates that the configurational entropy of the vortices may constitute a large part of their transport entropy at low magnetic field just below @xmath3 . we thank yayu wang and n. p. ong for providing us with the lsco data . we also thank them , shivaji sondhi and especially iddo ussishkin for many useful discussions . this work is supported by the nsf through mrsec grant dmr-0213706 . a. i. larkin and a. a. varlamov , in _ handbook on superconductivity , vol 1 : conventional and high - t@xmath126 superconductors _ , edited by k. h. bennemann and j. b. ketterson , ( springer , berlin , 2003 ) . , , , * * , ( ) .

we measure the transverse thermoelectric coefficient @xmath0 in simulations of type - ii superconductors in the vortex liquid regime , using the time - dependent ginzburg - landau ( tdgl ) equation with thermal noise . our results are in reasonably good quantitative agreement with experimental data on cuprate samples , suggesting that this simple model contains much of the physics behind the large nernst effect due to superconducting fluctuations observed in these materials .

during the past decades , quantum entanglement presented many useful properties in quantum information processing and transmission , such as quantum key distribution @xcite , quantum dense coding @xcite , quantum teleportation @xcite , and so on . in quantum communication , entangled states are used to built quantum channel for information transmission . however , in a practical condition the noise of the channel will inevitably affect the entangled quantum states and even make them be mixed states . the reduced entanglement of the quantum systems will decrease the success probability of quantum teleportation of an unknown state and even make a quantum key distribution insecure . for accomplishing the task of secret quantum communication , people should obtain some maximally entangled states from a less - entanglement ensemble , called entanglement purification . in 1996 , bennett et al . @xcite proposed the first protocol for entanglement purification of werner states with controlled - not ( cnot ) gates and bilateral rotations . in 2001 , pan et al . @xcite proposed an entanglement purification protocol with polarization beam splitters ( pbss ) and sophisticated single photon detectors . in 2003 , they experimentally demonstrated entanglement purification of bit - flip error by using pbss and four - path coincidence photon counters @xcite . also , entanglement purification based on the parametric down - conversion ( pdc ) source was presented by simon and pan @xcite . recently , sheng , deng and zhou @xcite introduced a perfect protocol for entanglement purification not only for pdc source but also for ideal source with nonlinear optics . so far , entanglement purification have been widely studied by many groups @xcite . considering the novel idea of entanglement with multiple degrees of freedom , many quantum communication protocols can be improved . for instance , aolita and walborn @xcite proposed a quantum communication protocol based on polarization and mode entangled state , which has a high capacity . barreiro et al . @xcite had demonstrated a superdense coding experiment based on two degrees of freedom of photons , which beats the channel capacity in quantum communication . in 2005 , ravaro et al . @xcite produced the doubly entangled state with two degrees of freedom , i.e. , the frequency and the polarization of photons . they generated two - photon states using semiconductor waveguides pumped by lasers . the spontaneous parametric down conversion process generates a pair of entangled photons with discrete frequencies . recently , xiao et al . @xcite studied the properties of doubly entangled photon state ( deps ) and proposed a entangled purification protocol for depss . this protocol can be realized with two steps , i.e. , the entanglement purification for bit - flip errors and that for phase - flip errors . two wavelength - division multiplexing ( wdm ) devices are used in the first step to exclude the states with bit - flip errors from the mixed ensemble . after the entanglement purification for bit - flip error , the two parties select two states from the remaining photon states and perform the pbs operations to distinguish the states from those with phase - flip errors . however , there is a problem in the second step as it requires that the two photon pairs should be in the same state , which means both of them should be in the state @xmath0 or in the state @xmath1 . in this way , the second step can not purify the ensemble in a mixed state with the unit fidelity . in this paper , we modify xiao s entanglement purification protocol for improving the success probability for entanglement purification of bit - flip errors and decreasing phase - flip errors . in the first step for the purification of bit - flip errors , we add two half wave plates ( hwps ) in the setups in xiao s protocol . just this modification will make all the entangled states with or without bit - flip errors kept as the bit - flip errors will be canceled by the spatial modes and the hwps . we complete the purification of phase - flip errors in the second step following some ideas from the protocol proposed by pan et al . this protocol has the advantage of high success probability and works more efficiently than xiao s protocol . the deps generated in ravaro s experiment can be described as @xcite : @xmath2 and @xmath3 correspond to the frequencies of entangled photons . considering the noisy channel transmission , we can not avoid the state to be disturbed . the bit - flip errors or phase - flip errors will take place on one of the particle or on both of the two particles . then the original state will be changed to @xmath4 in this time , a pure state system transmitted may become a mixed state ensemble described by the werner state @xmath5 here the coefficient @xmath6 is the fidelity of initial state @xmath7 . , width=302 ] since a deps exhibits two degrees of freedom , we can utilize the frequencies in our purification procedures to purify the polarizations of photons . in our protocol , we exploit the entanglement of frequencies to correct the bit - flip errors . its principle is shown in fig.[f1 ] . when a deps enters the device , one photon goes to the left wavelength - division multiplexing device ( wdm ) and the other to the right one . photons with different frequencies can be distinguished by recording their port information from wdms . since the two photons with different frequencies leave their respective wdm in either @xmath8 port or @xmath9 port , each photon passes through a polarizing beam splitter and then enters the port 1 , 2 , 3 or 4 . table [ t1 ] illustrates the correspondence between the ports that each photon leaves the device and the states . .the correspondence between the ports and the states [ cols="^,^,^,^,^,^,^",options="header " , ] from table [ t1 ] , one can see that the state has no bit - flip error if the two photons come out of the port 1 and the port 2 , respectively . if a photon comes out of the lower spatial mode ( the port 3 or the port 4 ) , a bit - flip error takes place on it . we can exploit the two hwps on the port 3 and the port 4 to correct the bit - flip errors in the photon pair . for example , for the bit - flip error state @xmath10 , the two photons a and b come out of the port 2 and the port 3 , respectively . that is , a bit - flip error takes place on the photon a coming out of the port 3 . the hwp on the port 3 will accomplish the transformation @xmath11 @xmath12 @xmath13 , which means that the state of the photon pair becomes @xmath7 after the setup shown in fig.1 . after the first step in our entanglement purification scheme , all the states in the mixed ensemble are preserved and the bit - flip errors are corrected . the deps system remains only the original state @xmath7 and the phase - flip error state @xmath14 . that is , the initial werner state becomes to @xmath15 compared with the xiao s protocol , we only add two hwps on the two ports 3 and 4 , but just this modification improves the efficiency of the entanglement purification of bit - flip errors largely . in an ideal condition , its efficiency for bit - flip error correction is 100% . in the second step , we purify the phase - flip error in the state @xmath16 . the key element before the second step is the wavelength conversion process @xcite which transforms the depss to traditional bell states by a up - conversion process : @xmath17 this conversion process is performed in the first step after the two wdms . the wavelength conversion process consists of a wdm coupler , a periodically poled lithium niobate ( ppln ) waveguide and a filter . one photon with the frequency @xmath18 pass through the wdm as a signal light and pumped by a high power laser with a certain wavelength . they are sent to ppln waveguide and the sum - frequency process generates the photon with the frequency @xmath19 needed . the filter is used to filter the pump light . the frequencies of both the a and b photons are performed by this wavelength conversion to the same frequency , and then the depss are transformed to bell states . , width=302 ] in the nonlocal entanglement purification procedures , the deps with phase - flip errors can be further distilled with the ways in other schemes existing , such as that with pbss and sophisticated single photon detectors @xcite , shown in fig.2 . in detail , the two parties , alice and bob , select two pairs of bell states ( marked with @xmath20 and @xmath21 ) randomly and perform a hadamard operation on each of the photons . after these operations , the phase - flip error state @xmath22 will be transformed into @xmath23 while the initial state @xmath24 remains unchanged . that is , the state @xmath16 becomes @xmath25 alice and bob choose the four - mode instances for their entanglement purification , same as that in ref . alice and bob performs @xmath26 measurement on the photons coming out of the port 3 and the port 4 , shown in fig.2 . if their outcomes are antiparallel , alice and bob need to take a phase - flip operation on the photon pair coming from the up modes . after this purification process , the state becomes @xmath27 where @xmath28 when @xmath29 is larger than @xmath30 , @xmath31 is larger than @xmath29 and the fidelity of the state @xmath32 can be improved iteratively , which means our entanglement purification scheme works at the case with the original fidelity @xmath33 , far lower than that in ref . @xcite . compared to the traditional purification protocols , our scheme is more efficient as the first step can correct all the bit - flip errors . this good feature makes the original fidelity of the entangled state wanted in our scheme much lower than others @xcite . in the second step for the purification of phase - flip errors , we can also use the ways in other protocols to improve the fidelity , such as that with nonlinear optics @xcite . in experiment , the probability of the wavelength conversion process is not unit , but it approaches unit @xcite . if the two parties possess some cross - kerr nonlinear media , it is possible for them to purify the phase - flip errors without the wavelength conversion process . in summary , we have improved the entangled purification scheme based on doubly entangled photon states . high fidelity depss can be achieved by two - step purification operations after the transmission over a noisy channel . we have modified the purification setups using wdms , polarization beam splitters and high efficiency nonlinear processes . in the first step operation , all the bit - flip error states can be distinguished and corrected . the second step operation can efficiently purify the phase - flip errors . moreover , the original fidelity of the entangled state wanted in our scheme is much lower than others @xcite , which makes this scheme more feasible in a practical application . this work is supported by the national natural science foundation of china under grant no .

recently xiao et al . proposed a scheme for entanglement purification based on doubly entangled photon states ( phys . rev . a 77(2008 ) 042315 ) . we modify their scheme for improving the efficiency of entanglement purification . this modified scheme contains two steps , i.e. , the bit - flip error correction and the entanglement purification of phase - flip errors . all the photon pairs in the first step can be kept as all the bit - flip errors are corrected . for purifying the phase - flip errors , a wavelength conversion process is needed . this scheme has the advantage of high efficiency and it requires the original fidelity of the entangled state wanted fay lower than other schemes , which makes it more feasible in a practical application .

thyroxine ( t4 ) and triiodothyronine ( t3 ) , the two main thyroid hormones , are secreted after thyroglobulin macropinocytosis and hydrolysis under the stimulation of pituitary thyrotropin ( tsh ) and are present in the blood mainly in noncovalent interactions with thyroxine - binding globulin , prealbumin , and albumin . only 0.4% t3 and 0.04% t4 dynamically escape binding and , since free to interact directly with peripheral organs and tissues , are called free t3 ( ft3 ) and free t4 ( ft4 ) and are the only fractions believed to be metabolically active . ft4 levels are about 100 times higher than those of ft3 , which is considered to be the most active form of thyroid hormone and into which ft4 is converted within the peripheral tissue . inside a variety of cells , both interact with different affinity with 1 , 2 , 1 , and 2 nuclear receptors in regulating the expression of target genes through the so - called thyroid response elements ( tre 's ) , thus exerting the typical physiological functions which characterize them . these are mostly represented by enhanced calorigenesis , increased stroke volume and heart rate , enhanced sensitivity to catecholamines , bone turnover , gluconeogenesis , glycogenolysis , and lipolysis . the latter is mainly due to enhanced lipoprotein - lipase activity and increased hepatic low - density lipoprotein ( ldl ) receptor concentrations . besides genomic effects , widespread rapid onset nongenomic effects of ft3 and ft4 have been reported involving membrane - signalling pathways , the real extent of which has not been well defined yet . when dealing with lipid metabolism , circulating t4 concentrations have always been found to be inversely associated with total ( tc ) , high - density lipoprotein ( hdl - c ) , and ldl cholesterol ( ldl - c ) levels . in fact , high tc levels in hypothyroidism are caused by a reduction in ldl receptors and l - t4 administration has a hypolipidemic effect in hypothyroidism , which is characterized by high thyrotropin ( tsh ) concentrations , meant at compensating for low ft4 levels . thus , there is a greater benefit in patients displaying higher pretreatment tc or ldl - c and tsh despite the difficulty to identify any well - defined cut - off threshold for the association of the latter with lipids . as a matter of fact , 4.3% hypercholesterolemic patients have been reported to be hypothyroid . a contributing factor to high cholesterol levels in hypothyroidism the latter has the control over sterol regulatory element - binding protein-1 ( srebp-1 ) , a crucial step for the expression of the ldl receptor , rather than over srebp-2 . however , it also acts directly by inducing at least two ldl - receptor tre 's in the liver . finally , increased flow of bile acids as a result of ft3 and ft4 is known to reduce cholesterol levels by depletion of its hepatic pool ; however , such effect is counterbalanced by enhanced synthesis and uptake in the liver , eventually increasing tc and ldl - c under unfavourable circumstances . based on the considerations mentioned above , the relationship between thyroid function and the metabolic syndrome ( mets ) has become a subject of interest for many research groups during the last few years , leading to the conclusion that even low - normal t4 levels may contribute to increased cardiovascular risk associated with lipoid abnormalities in people with the mets . some of these studies reported that t3 behaved in a different way , being positively associated with body mass index ( bmi ) and waist girth [ 1618 ] . a higher compensatory conversion of t4 to t3 to increase thermogenesis in obesity was the hypothesized mechanism [ 19 , 20 ] . diabetes mellitus ( dm ) , in particular type 2 ( t2 dm ) , which is mostly associated with lipoid abnormalities and displays an increasing prevalence with age , is also known to dramatically increase cardiovascular risk ( cvr ) at any age . age does not seem to affect ft3 and ft4 levels in the human , whereas people with dm have been reported to suffer from thyroid dysfunction twice as much as the nondiabetic population . nevertheless , despite the fact that tc and ldl - c are major cvr factors identified as crucial targets in all current diabetes treatment guidelines , no extensive investigation can be found in the literature concerning the relation between thyroid and lipids in t2 dm . this link is missing in the clinical management of people with dm now that carbohydrate response element - binding protein ( chrebp)a newly identified lipogenic glucose - sensing transcription factor controlling hepatic lipogenesis is known to be positively controlled by t3 in mammals through its binding to thyroid receptor -1 . in fact , t3 has been shown to modulate hepatic lipogenesis through reciprocal regulation of srebp-1c and chrebp gene expression . moreover , t3 is endowed with a lipogenic effect via chrebp enhancement in white adipose tissue , where both and thyroid receptors are expressed but only the isoform is active with regard to that effect . thus , glucose , lipids , and thyroid hormones seem to interact according to a more complex mathematical function than as previously expected . taking into account the considerations mentioned above , with the present study , we evaluated the relations among ft3 , ft4 , tc , and ldl - c in elderly euthyroid people with t2 dm . we retrospectively evaluated clinical records from 350 outpatients , ages 70 years and older , referred to our clinic for t2 dm during the last three years . all of them had thyroid function routinely evaluated in terms of ft3 , ft4 , and tsh concentrations . exclusion criteria included smoking and any complications worse than background retinopathy , microalbuminuria , low - grade neuropathy , and nonobstructive arteriopathy . we also did not accept for this study patients with overt heart , liver or kidney failure , hypo / hyperthyroidism , or those on any medications possibly interfering with thyroid function . thus , 296 people were qualified for study ( 245 women , 51 men ) , all taking statins since the time of diagnosis ( 4,5 2,7 years ) in order to prevent cardiovascular complications according to italian diabetes guidelines . they were either under oral hypoglycaemic agents ( oha subgroup , n = 196 ) , invariably consisting of sulphonylureas and metformin , or under insulin treatment ( it subgroup , n = 100 , of which 63 on 4 basal - bolus injections , the others with 2 or 3 injections as needed ) . both subgroups followed a thorough self - monitoring blood glucose supervision associated with a strong empowering strategy . blood was drawn in our laboratory in the morning , after a 12-hour overnight fast . chemistry was measured by kodak blood multiple analyzer and thyroid hormones by immulite 2000 immunoassay system . data evaluation was based upon spss 13.0 for descriptive ( mean sd ) and correlation analysis . correlation analysis was performed first on all cases and then completed by partial correlation analysis applied to each subgroup ( namely , oha and it ) , controlling for possible confounding factors . the least statistical significance of the differences among the means and of the associations was set at p < 0.05 . for clarification concerning the abbreviations used within the text the means and the standard deviations ( s.d . ) of all recorded clinical parameters are presented in table 1 . when analysing all the cases , we observed a positive correlation of ft3 with both tc ( r = 0.144 , p < 0.05 ) and ldl - c ( r = 0.161 , p < 0.02 ) . conversely , ft4 correlated negatively with tc and ldl - c ( r = 0.131 , p < 0.05 and r = 0.134 , p < 0.05 , resp . ) . the disease duration and hba1c were found to correlate negatively with ldl - c ( r = 0.108 , p < 0.05 and r = 0.144 , p < 0.02 , resp . ) . to avoid confounding effects , we introduced them together with other potentially interfering factors that are possibly related to thyroid function ( age , bmi , and blood pressure ) into partial correlation analysis of total and ldl - c with ft3 and ft4 . as a result , no changes in correlation coefficient signs or significances were observed . at this point , when we proceeded to further analyze the variance of observed parameters between oha and it subgroups , we found that the two were statistically homogenous with each other , as shown in table 2 . though , in terms of correlation analysis , the two subgroups behaved differently in terms of thyroid hormones . in fact , in the oha , total and ldl cholesterol showed no correlation with ft3 ( r = 0.037 and r = 0.098 , resp . , nonsignificant ) but correlated negatively with ft4 ( r = 0.144 , p < 0.05 and r = 0,145 , p < 0,05 ) . conversely , in the it , total , and ldl cholesterol correlated positively with ft3 ( r = 0.291 , p < 0.01 and r = 0.275 , p < 0.02 , resp . ) while maintaining the same negative correlation with ft4 , as observed in the oha ( r = 0.239 , p < 0.05 and r = 0.186 , p < 0.05 ) . moreover , the it revealed a previously hidden negative correlation between hdl cholesterol and ft4 ( r = 0.302 , p < 0.01 ) . we then repeated the same correlation analysis controlling lipid to thyroid relationship for age , bmi , hba1c , blood pressure , and disease duration within each subgroup . as clearly shown in figure 1 , we could therefore confirm the positive correlation of ft3 with ldl cholesterol . moreover , as summarized in table 3 , all the correlations previously described before were confirmed , including the one linking ft4 to hdl cholesterol . tc and ldl - c displayed opposite correlations with ft3 ( positive ) and ft4 ( negative ) in elderly euthyroid subjects with t2 dm . while a negative correlation would have been easy to accept and understand for thyroid hormones , a positive one was totally unexpected according to current concepts . when repeating the analysis in the two different subgroups , controlling them for confounding factors , we confirmed the above findings in the it subgroup but not in the oha subgroup . however , regarding the clinical implications of our results , a crucial point is that elderly people with t2 dm carry the burden of a high cvr and have to be treated as carefully as their younger counterpart since morbility / mortality increases together with their ldl - c levels . with this in mind , diabetologists often concentrate on glucose , lipids , and blood pressure and generally do not take into account thyroid hormones in the absence of typical symptoms of thyroid dysfunction . on the other hand , subclinical hypo- and hyperthyroidism are not rare at all . as geriatric endocrinologists , we prefer to assay thyroid hormones in diabetic elderly patients in order to rule out any subtle thyroid malfunction during the course of overall evaluation . such a habit allowed us to collect data from a number of euthyroid elderly people with t2 dm and to perform a correlation analysis between cholesterol and thyroid hormones . with regard to ft4 , the analysis confirmed that thyroid function negatively correlates with tc and ldl - c , a trend commonly found in the general population . however , quite unexpectedly ft3 behaved the opposite way , being positively associated with tc and ldl - c . we found that age correlated positively and hba1c and negatively to tc and ldl - c . therefore , we introduced these two factors and other potentially interfering parameters including bmi , blood pressure , and disease duration as confounding factors , confirming their associations by performing partial correlation analysis . after we divided our subjects into oha and it subgroups , the analysis of variance showed that they were fully homogeneous in terms of recorded clinical parameters . the only difference was in their treatment , namely , metformin / sulphonylureas versus insulin . this made us more confident in trying to reveal eventual differences occurring in relations between lipid profile and thyroid hormones . in fact , this would allow us to check whether different associations within subgroups are possibly linked to different treatment regimens . in the oha group , tc and ldl - c displayed no correlation with ft3 but correlated negatively with ft4 ( p < 0.05 ) , whereas in the it group , tc and ldl - c correlated positively with ft3 ( p < 0.02 ) and negatively with ft4 ( p < 0.05 ) . once again we performed partial correlation analysis in the it subgroup and found that the positive association of lipids with ft3 became even stronger while that with ft4 remained the same ( see table 3 ) ; however , both vanished in the oha subgroup . such findings might seem contradictory , but , in fact , they fit well with the role played by ft3 on srebp-1 and srebp-2 control , and consequently on the expression of ldl receptor , with its ability to indirectly enhance cholesterol synthesis and uptake by the liver . moreover , in some previous studies an unexpected positive association between ft3 and lipids was mentioned without indepth explanation , and therefore remained underestimated . for instance , de pergola et al . found that ft3 correlated negatively with hdl - c levels ( p < 0.001 ) , and , in multiple correlation analysis , maintained an independent positive association with age ( p < 0.001 ) , waist girth ( p < 0.05 ) and insulin levels ( p < 0.001 ) , a proxy for insulin resistance . our study took into account only nonsmokers , thus ruling out a priori a possible strong confounding factor . others confirmed the previously mentioned association between ft3 and mets components suggesting insulin - resistance to be the link between the thyroid and lipids . therefore , t3 may act as a strong independent metabolic signal in euthyroid insulin - resistant t2 dm patients [ 33 , 34 ] . interestingly enough , according to recent reports , t3 added to diets containing peanut oil increased serum lipids in rats , sometimes even up to 20-fold , whereas t3 was found to increase cholesterol biosynthesis in the liver through the activation of de novo protein synthesis [ 36 , 37 ] . furthermore , t3 , insulin , and their combination markedly stimulate cholesterol synthesis in cultured human skin fibroblasts , and in recent studies ft3 has been even shown to exert a beta - cell protective effect [ 39 , 40 ] . all above considerations might explain the association we found between ft3 and tc and ldl - c in our it patients and not in our oha patients . in fact , it seems as if in the presence of insulin resistance t3 may not be able to act as fully as in the case of an unopposed insulin signal , such as when metabolically effective exogenous insulin levels are attained . still another possible explanation for our findings result from an eventual compensatory increase in ft3 . in fact , based upon widely accepted lipid metabolism regulation mechanisms by thyroid hormones , it might be hypothesized that in our patients cholesterol synthesis might have been enhanced by exogenous insulin and by peripheral t3 conversion from t4 [ 41 , 42 ] . another apparently anomalous finding , regarding the negative correlation of hdl - c with ft4 levels ( p < 0.01 ) but not with ft3 , deserves more discussion . since early studies in the field , hdl - c was found to decrease both in hypo- and in hyperthyroidism , thus indicating that such association followed a u - shaped curve and could , therefore , only be analyzed within the physiological range of ft4 concentrations [ 43 , 44 ] . in fact , slightly different behaviour between the two hormones has been reported in the literature , including a stronger enhancing effect of hdl - c on t4 target cell penetration in comparison to t3 target cell penetration . a pro - hdl and anti - ldl effect of t3 these observations have been often overlooked , despite their potential pharmacologic utilization in the metabolic syndrome . we are aware of the intrinsic limits of the retrospective cross - sectional character of our study , which refers to subjects over 70 years of age with t2 dm and , therefore , allows no definite conclusions with regard to younger people or in terms of cause - effect relationships . nevertheless , due to the different association patterns found in it patients as compared to oha patients , we feel it is worthwhile to further investigate the topic . specifically , reported data prompts some reappraisal regarding the relationship among some hidden aspects of cholesterol , insulin , and thyroid hormone metabolism , eventually fostering new controlled studies concerning the role of t3 in t2 dm and the possible pharmacological interferences that different drugs may have on it . based on our data , it seems more prudent to treat elderly hypothyroid patients with t4 , without any t3 integration if they are on insulin . this might prevent the risk of letting their ldl - c increase and thus of increasing statin dosage . we still do not fully understand the meaning of the association we found between ft3 and cholesterol in it people with t2 dm . in other terms , the positive association might be the expression of a compensatory hormone response to spontaneous ldl - c increase , as already hypothesized for patients with the mets [ 15 , 33 , 34 ] and in line with the complex dm - thyroid interactions occurring via hypothalamic glucose sensing mechanisms ( as recently reviewed by duntas et al . ) . in conclusion , in order to clarify the pathophysiological mechanisms underlying the observed results further experimental and clinical follow - up studies are needed . should the observed associations be confirmed by future investigations , in older t2 dm patients it might be useful to include ft3 once again in thyroid test panels which today are mostly limited to screening tsh and confirmation ft4 .

thyroid function regulates lipid metabolism . despite the fact that t2 dm is more prevalent in the elderly , often associates with thyroid dysfunction and increases cardiovascular risk both per se and via high tc and ldl - c levels , the association of the latter with ft3 and ft4 levels has not yet been fully investigated in t2 dm . while trying to fill this gap in 296 elderly outpatients with t2 dm , we found that tc and ldl - c correlated negatively with ft4 and positively with ft3 . when divided according to treatment by oral hypoglycaemic agents ( oha ) and insulin ( it ) , they reacted differently with respect to investigated associations : in the oha 's tc and ldl - c correlated negatively with ft4 and showed no association with ft3 , whereas , in the it 's tc and ldl - c correlated positively with ft3 and negatively with ft4 . when controlled for possible confounding factors , these associations did not change in the it 's but were missing in the oha 's . recent literature reports upon complex hypothalamic and peripheral interactions between t2 dm and thyroid , and suggests t3 to enhance cholesterol synthesis and to have a role in insulin resistance states . further investigations are needed to understand the intimate mechanisms of lipid metabolism in t2 dm with respect to thyroid function .

A pregnant Texas teenager is suing her parents to stop them from forcing her to abort her unborn child. Click2Houston reports a judge issued a temporary restraining order to prevent the abortion while the case is ongoing. The 16-year-old, who is identified only by the initials R.E.K. because she is a minor, claims in the lawsuit her parents are coercing her to abort her 9-week-old fetus through both verbal and physical threats and harassment. "(The father) stated he was going to take her to have an abortion and that the decision was his, end of story," a copy of the lawsuit obtained by Click2Houston says. Click here to read the lawsuit. The lawsuit claims R.E.K.'s parents kept her home from school, took her phone and car and that she, the father of her child and the child's paternal grandmother have been harassed by her father. It also claims R.E.K.'s mother suggested she was going to slip her daughter the abortion pill. R.E.K is being represented by attorney for the Texas Center for Defense of Life. "...She is legally protected. They cannot drag her to get an abortion, force an abortion on our client," attorney Stephen Casey told Click2Houston. Under Roe v. Wade a woman has a right to decide whether she wants an abortion and under Bellotti v. Baird a teenager has the right to make her own decisions concerning her reproductive health. Click for more from Click2Houston. ||||| Teen claims parents are trying to make her have abortion HOUSTON - A lawsuit claims a 16-year-old girl is being coerced to have an abortion against her will. The teen is two months pregnant and is represented by lawyers with the Texas Center for Defense of Life. A judge granted a temporary restraining order to save the baby's life. "We were asking judge to stop them physically forcing her to have an abortion. She is legally protected. They cannot drag her to get an abortion, force an abortion on our client," attorney Stephen Casey said. The lawsuit is eight pages long and details alleged verbal abuse by the teen's parents. In the lawsuit, the teen claims her mom "... invited the paternal grandparents to a bar for further discussion, where she suggested that she might slip her an abortion pill through deception." The teen also claims her father told her "he was going to take her to have an abortion and that the decision was his, end of story." Even though she is a minor, the teen has the power to make that decision. "What Roe established is minors have the choice. And when they do make the choice, folks are shocked that they want to carry the baby," said Casey. Another hearing will be held Friday.

– A pregnant 16-year-old in Texas has won a temporary restraining order after taking her parents to court to stop them from forcing her to get an abortion, reports Fox News. The unnamed girl, identified only as REK, claims in her lawsuit that her father said "the decision was his, end of story." Click2Houston adds that the girl's mother "invited the paternal grandparents to a bar for further discussion, where she suggested that she might slip her an abortion pill." Both parents have used verbal and physical threats in an attempt to force REK to have an abortion, according to the lawsuit, kept her out of school, and harassed the baby's father, as well as his mother. REK is being represented by a lawyer for the Texas Center for Defense of Life. "What Roe established is minors have the choice," says her lawyer. "And when they do make the choice, folks are shocked that they want to carry the baby."

the median age of the sample was 60 years ( range : 3587 years ) . all were in - patients in a coronary intensive care unit ( getafe hospital , madrid ) and were evaluated , in the first instance , within the first 4872 hours after the mi . a number of exclusion criteria were used : having suffered a similar episode on other occasions.being less than 18 years of age.not being fluent in spanish.having a mental condition ( e.g. dementia or psychotic episode ) impeding a coherent interview . not being fluent in spanish . having a mental condition ( e.g. dementia or psychotic episode ) impeding a coherent interview . after 45 months ( mdn=4.63 ) , follow - up was made with 48 of the patients ( i.e. , 63% of the original sample ) and , after 13 months ( mdn=13.21 ) , 33 participants were evaluated ( i.e. , 43.4% of the original sample ) . in the analysis of the data from the follow - up , only the final group of 33 participants who completed the three evaluations of the study was included . the principal causes of attrition were : inability to contact the patient due to change of telephone or domicile ( 32.5% ) , lack of desire of patient to continue participation or being too busy ( 32.5% ) , death of the patient ( 18.6% ) , and difficulty in traveling to the hospital to perform the interview ( 16.3% ) . an analysis was made to ensure that the participants who continued in t2 and t3 had no socio - demographic or clinical difference to those who did not continue in the study . no significant difference was found with regard to any of the variables analyzed ( age , gender , and clinical and psychological measures ) . the mi patients were interviewed for the first time in the coronary unit 4872 hours after their admission to the hospital ( t1 ) . after acceptance to participate in the study and the signing of consent forms , the evaluation protocol was applied for a period of approximately 60 min . five months after the mi ( t2 ) and again after 13 months ( t3 ) , the patients were contacted by telephone and called to the hospital where the follow - up protocol was applied for duration of approximately 40 min . within a more extensive protocol , some of the instruments used in the three stages of the evaluation ( t1 , t2 , and t3 ) were : the ptsd checklist ( pcl - c ; weathers , litz , herman , huska , & keane , 1993 ) . this questionnaire evaluates , on a scale of 1 to 5 , the severity of the 17 symptoms covering the criteria b ( re - experiencing ) , c ( avoidance ) , and d ( hyperarousal ) of the dsm - iv ( apa , 1994 ) for post traumatic stress disorder . the cronbach 's alpha values in our study were 0.80 ( total score ) , 0.69 ( re - experiencing ) , 0.68 ( avoidance ) , and 0.62 ( hyperarousal ) . the ptsd checklist ( pcl - c ; weathers , litz , herman , huska , & keane , 1993 ) . this questionnaire evaluates , on a scale of 1 to 5 , the severity of the 17 symptoms covering the criteria b ( re - experiencing ) , c ( avoidance ) , and d ( hyperarousal ) of the dsm - iv ( apa , 1994 ) for post traumatic stress disorder . the cronbach 's alpha values in our study were 0.80 ( total score ) , 0.69 ( re - experiencing ) , 0.68 ( avoidance ) , and 0.62 ( hyperarousal ) . first , in order to determine the probable prevalence of ptsd , we implemented the criterion most used in the literature ( i.e. , total score>44 ; blanchard et al . second , in order to verify the percentage of participants likely to have separate symptom clusters ( i.e. , criteria b , c , and d of the dsm - iv - tr ( apa , 2000 ) for ptsd ) , the percentage of participants meeting each criterion of the pcl - c was analyzed . we considered the criteria met ( see vzquez , prez - sales , & matt , 2006 ) if the participant had a severity rating of 4 or more on the 5-point likert scale in the minimum number of symptoms required for each criterion of the dsm - iv - tr ( i.e. , one of the five for re - experiencing , three of the seven for avoidance , and two of the five for hyperarousal ) . three items on a 110 likert - type scale were used , referring to a subjective reaction to the mi : perception of danger ( did you feel that your life was in danger ? ) , if the situation was traumatic for the patient ( would you describe the event as traumatic for you ? ) and perception of the severity of the situation ( to what point would you describe what has happened to you as severe ? ) . goldberg health questionnaire ( ghq-12 ) ( goldberg & williams , 1996 ) . the objective of this questionnaire , widely used in epidemiological studies in the general population , is to evaluate general distress . it consists of 12 items with 4 request options on a likert - type scale . as some authors have proposed recently ( hu , steward - brown , twigg , & weich , 2007 ) , the scoring can be divided by separately taking into account the six items that evaluate a state of positive mental health ( e.g. , have you been able to concentrate on things ? ) and the six items that evaluate a state of negative mental health or general distress ( e.g. , the cronbach 's alpha values were 0.65 ( ghq12 ) , 0.51 ( ghq6 : positive mental health ) , and 0.74 ( ghq6 : general distress ) . life orientation test revised ( lot - r , scheier , carver , & bridges , 1994 ) . the test measures dispositional optimism or the generalized predisposition towards the expectation of positive results . it consists of six specific items of which three evaluate optimism and three evaluate pessimism . an additional item was added , in the same answer format , which specifically asked about the patient 's expectations with regard to a complete recovery from the infarction ( i believe i 'm going to come out of this heart problem i have completely fine ) . positive and negative affect schedules ( watson , clark , & tellegen , 1988 ) . the panas is a widely used instrument for measuring affect by means of a listing of 20 emotions ( 10 positive and 10 negative ) . the cronbach 's alpha values were 0.84 for the positive subscale and 0.82 for the negative subscale . perceived importance of the heart failure . three items on a 110 likert - type scale were used , referring to a subjective reaction to the mi : perception of danger ( did you feel that your life was in danger ? ) , if the situation was traumatic for the patient ( would you describe the event as traumatic for you ? ) and perception of the severity of the situation ( to what point would you describe what has happened to you as severe ? ) . the objective of this questionnaire , widely used in epidemiological studies in the general population , is to evaluate general distress . it consists of 12 items with 4 request options on a likert - type scale . as some authors have proposed recently ( hu , steward - brown , twigg , & weich , 2007 ) , the scoring can be divided by separately taking into account the six items that evaluate a state of positive mental health ( e.g. , have you been able to concentrate on things ? ) and the six items that evaluate a state of negative mental health or general distress ( e.g. , the cronbach 's alpha values were 0.65 ( ghq12 ) , 0.51 ( ghq6 : positive mental health ) , and 0.74 ( ghq6 : general distress ) . life orientation test revised ( lot - r , scheier , carver , & bridges , 1994 ) . the test measures dispositional optimism or the generalized predisposition towards the expectation of positive results . it consists of six specific items of which three evaluate optimism and three evaluate pessimism . an additional item was added , in the same answer format , which specifically asked about the patient 's expectations with regard to a complete recovery from the infarction ( i believe i 'm going to come out of this heart problem i have completely fine ) . positive and negative affect schedules ( watson , clark , & tellegen , 1988 ) . the panas is a widely used instrument for measuring affect by means of a listing of 20 emotions ( 10 positive and 10 negative ) . the cronbach 's alpha values were 0.84 for the positive subscale and 0.82 for the negative subscale . the median age of the sample was 60 years ( range : 3587 years ) . all were in - patients in a coronary intensive care unit ( getafe hospital , madrid ) and were evaluated , in the first instance , within the first 4872 hours after the mi . a number of exclusion criteria were used : having suffered a similar episode on other occasions.being less than 18 years of age.not being fluent in spanish.having a mental condition ( e.g. dementia or psychotic episode ) impeding a coherent interview . not being fluent in spanish . having a mental condition ( e.g. dementia or psychotic episode ) impeding a coherent interview . after 45 months ( mdn=4.63 ) , follow - up was made with 48 of the patients ( i.e. , 63% of the original sample ) and , after 13 months ( mdn=13.21 ) , 33 participants were evaluated ( i.e. , 43.4% of the original sample ) . in the analysis of the data from the follow - up , only the final group of 33 participants who completed the three evaluations of the study was included . the principal causes of attrition were : inability to contact the patient due to change of telephone or domicile ( 32.5% ) , lack of desire of patient to continue participation or being too busy ( 32.5% ) , death of the patient ( 18.6% ) , and difficulty in traveling to the hospital to perform the interview ( 16.3% ) . an analysis was made to ensure that the participants who continued in t2 and t3 had no socio - demographic or clinical difference to those who did not continue in the study . no significant difference was found with regard to any of the variables analyzed ( age , gender , and clinical and psychological measures ) . the mi patients were interviewed for the first time in the coronary unit 4872 hours after their admission to the hospital ( t1 ) . after acceptance to participate in the study and the signing of consent forms , the evaluation protocol was applied for a period of approximately 60 min . five months after the mi ( t2 ) and again after 13 months ( t3 ) , the patients were contacted by telephone and called to the hospital where the follow - up protocol was applied for duration of approximately 40 min . within a more extensive protocol , some of the instruments used in the three stages of the evaluation ( t1 , t2 , and t3 ) were : the ptsd checklist ( pcl - c ; weathers , litz , herman , huska , & keane , 1993 ) . this questionnaire evaluates , on a scale of 1 to 5 , the severity of the 17 symptoms covering the criteria b ( re - experiencing ) , c ( avoidance ) , and d ( hyperarousal ) of the dsm - iv ( apa , 1994 ) for post traumatic stress disorder . the cronbach 's alpha values in our study were 0.80 ( total score ) , 0.69 ( re - experiencing ) , 0.68 ( avoidance ) , and 0.62 ( hyperarousal ) . the ptsd checklist ( pcl - c ; weathers , litz , herman , huska , & keane , 1993 ) . this questionnaire evaluates , on a scale of 1 to 5 , the severity of the 17 symptoms covering the criteria b ( re - experiencing ) , c ( avoidance ) , and d ( hyperarousal ) of the dsm - iv ( apa , 1994 ) for post traumatic stress disorder . the cronbach 's alpha values in our study were 0.80 ( total score ) , 0.69 ( re - experiencing ) , 0.68 ( avoidance ) , and 0.62 ( hyperarousal ) . first , in order to determine the probable prevalence of ptsd , we implemented the criterion most used in the literature ( i.e. , total score>44 ; blanchard et al . , 2004 ) . second , in order to verify the percentage of participants likely to have separate symptom clusters ( i.e. , criteria b , c , and d of the dsm - iv - tr ( apa , 2000 ) for ptsd ) , the percentage of participants meeting each criterion of the pcl - c was analyzed . we considered the criteria met ( see vzquez , prez - sales , & matt , 2006 ) if the participant had a severity rating of 4 or more on the 5-point likert scale in the minimum number of symptoms required for each criterion of the dsm - iv - tr ( i.e. , one of the five for re - experiencing , three of the seven for avoidance , and two of the five for hyperarousal ) . three items on a 110 likert - type scale were used , referring to a subjective reaction to the mi : perception of danger ( did you feel that your life was in danger ? ) , if the situation was traumatic for the patient ( would you describe the event as traumatic for you ? ) and perception of the severity of the situation ( to what point would you describe what has happened to you as severe ? ) . the objective of this questionnaire , widely used in epidemiological studies in the general population , is to evaluate general distress . it consists of 12 items with 4 request options on a likert - type scale . as some authors have proposed recently ( hu , steward - brown , twigg , & weich , 2007 ) , the scoring can be divided by separately taking into account the six items that evaluate a state of positive mental health ( e.g. , have you been able to concentrate on things ? ) and the six items that evaluate a state of negative mental health or general distress ( e.g. , the cronbach 's alpha values were 0.65 ( ghq12 ) , 0.51 ( ghq6 : positive mental health ) , and 0.74 ( ghq6 : general distress ) . life orientation test revised ( lot - r , scheier , carver , & bridges , 1994 ) . the test measures dispositional optimism or the generalized predisposition towards the expectation of positive results . it consists of six specific items of which three evaluate optimism and three evaluate pessimism . an additional item was added , in the same answer format , which specifically asked about the patient 's expectations with regard to a complete recovery from the infarction ( i believe i 'm going to come out of this heart problem i have completely fine ) . positive and negative affect schedules ( watson , clark , & tellegen , 1988 ) . the panas is a widely used instrument for measuring affect by means of a listing of 20 emotions ( 10 positive and 10 negative ) . the cronbach 's alpha values were 0.84 for the positive subscale and 0.82 for the negative subscale . perceived importance of the heart failure . three items on a 110 likert - type scale were used , referring to a subjective reaction to the mi : perception of danger ( did you feel that your life was in danger ? ) , if the situation was traumatic for the patient ( would you describe the event as traumatic for you ? ) and perception of the severity of the situation ( to what point would you describe what has happened to you as severe ? ) . the objective of this questionnaire , widely used in epidemiological studies in the general population , is to evaluate general distress . it consists of 12 items with 4 request options on a likert - type scale . as some authors have proposed recently ( hu , steward - brown , twigg , & weich , 2007 ) , the scoring can be divided by separately taking into account the six items that evaluate a state of positive mental health ( e.g. , have you been able to concentrate on things ? ) and the six items that evaluate a state of negative mental health or general distress ( e.g. , did you feel constantly under strain ? ) . the cronbach 's alpha values were 0.65 ( ghq12 ) , 0.51 ( ghq6 : positive mental health ) , and 0.74 ( ghq6 : general distress ) . life orientation test revised ( lot - r , scheier , carver , & bridges , 1994 ) . the test measures dispositional optimism or the generalized predisposition towards the expectation of positive results . it consists of six specific items of which three evaluate optimism and three evaluate pessimism . an additional item was added , in the same answer format , which specifically asked about the patient 's expectations with regard to a complete recovery from the infarction ( i believe i 'm going to come out of this heart problem i have completely fine ) . positive and negative affect schedules ( watson , clark , & tellegen , 1988 ) . the panas is a widely used instrument for measuring affect by means of a listing of 20 emotions ( 10 positive and 10 negative ) . the cronbach 's alpha values were 0.84 for the positive subscale and 0.82 for the negative subscale . table 2 presents the data obtained in each of the questionnaires of the evaluation protocol . characteristics , in the three times of assessment , of the sample who completed all the follow - ups ( n=33 ) notes : pcl , the ptsd checklist ; ghq , goldberg health questionnaire ( 12- and six - item versions ) ; lot - r , life orientation testrevised ; panas , positive and negative affective schedules . in the first place , a series of repeated measures anovas revealed no significant time differences on participants scores on pcl total score [ f ( 2 , 29)=2.29 , ns ] and on two subscales : pcl - re - experiencing [ f ( 2 , 31)=2.69 , ns ] and pcl - avoidance [ f ( 2,29)=0.45 , ns ] . nevertheless , significant differences were encountered in the scale of hyperarousal [ f ( 2 , 31)=3.66 , p=0.038 ] . a post - hoc bonferroni analysis showed that hyperarousal was significantly greater in t2 than in t1 ( p<0.044 ) . yet , as it can be shown in table 2 , the overall scores for each subscale were , in general , very close to the minimum possible level of severity . with regard to the assessment of the perceived importance of the event , a repeated - measures analysis showed a significant time effect for traumatic event [ f ( 2 , 32)=20.00 ; p=0.0001 ] . traumatic at baseline ( t1 ) than 5 months later ( t2 ) or 13 months later ( t3 ) ; there were no differences between t2 and t3 . mean scores of this variable were close to the maximum possible score both at t2 ( m=8.76 ) and t3 ( m=8.97 ) ( see table 2 ) . two additional anovas on the perception of life at risk and having a perception of severity did not show time effects . yet , participants perception of these two variables was remarkably different . mean score for life at risk was significantly lower than that of perception of severity at any time of measurement : t1 : [ t ( 31)=-3.45 ; p=0.002 ] ; t2 : [ t ( 32)=5.89 ; p=0.0001 ] ; t3 : [ t ( 31)=7.27 ; p=0.0001 ] . regarding the scores in the ghq12 , we ran a 3 x 2 anova ( time x positive / negative mental health ) , which only yielded significant results for the positive / negative factor [ f ( 2 , 33)=45.90 ; p=0.0001 ] . positive mental health scores were higher than negative mental health scores ( i.e. , general distress ) at any time of assessment : t1 : [ t ( 29)=7.06 ; p=0.0001 ] ; t2 : [ t ( 30)=5.19 ; p=0.0001 ] ; t3 : [ t ( 31)=8.35 ; p=0.0001 ] . in regard to positive and negative emotions , we ran a 3 x 2 repeated measures anova on the panas scores ( time x positive / negative affect ) , which only yielded a main effect for positive / negative affect [ f ( 16)=26.90 ; p=0.0001 ] . furthermore we found that the levels of positive affect were greater than those of negative affect in the three evaluations carried out at t1 [ t ( 31)=6.49 ; p=0.0001 ] , t2 [ t ( 18)=3.51 ; p=0.002 ] , and t3 : [ t ( 31)=8.37 ; p=0.0001 ] . finally , a series of one - way anovas on dispositional optimism ( i.e. , lot - r ) and optimism on a full recovery from the heart problem showed that there were no changes in scores of both measures across the three times of measurement [ f(2 , 29)=0.26 , ns and f ( 2 , 29)=0.73 , ns , respectively ] . furthermore , as can be seen in table 2 , scores on both types of optimism , as well as in the rest of measures of positive affect , were consistently high across time . as can be seen in table 3 , using a cut - off score of pcl - c>44 , the probable prevalence of significant stress reaction in t1 is very low , rising to a prevalence of 11.1% after 5 months . finally , the number of cases with probable diagnoses of ptsd declines 13 months after the event ( 3.1% ) . probable prevalence of ptsd based on a selected cutoff score for the ptsd checklist ( pcl - c ) and percentage of patients fulfilling criteria for each of the three symptom clusters in regard to the prevalence of specific syndromes ( see measures section ) , it was found that , at each point of measurement , re - experiencing was the criterion that appeared in the greatest number of participants while the criterion of avoidance was that of least prevalence in the patients evaluated ( table 3 ) . the progression of the three steps over time was similar : the moment at which most subjects met the criteria was at five months after the mi , while mitigating later . table 2 presents the data obtained in each of the questionnaires of the evaluation protocol . characteristics , in the three times of assessment , of the sample who completed all the follow - ups ( n=33 ) notes : pcl , the ptsd checklist ; ghq , goldberg health questionnaire ( 12- and six - item versions ) ; lot - r , life orientation testrevised ; panas , positive and negative affective schedules . in the first place , a series of repeated measures anovas revealed no significant time differences on participants scores on pcl total score [ f ( 2 , 29)=2.29 , ns ] and on two subscales : pcl - re - experiencing [ f ( 2 , 31)=2.69 , ns ] and pcl - avoidance [ f ( 2,29)=0.45 , ns ] . nevertheless , significant differences were encountered in the scale of hyperarousal [ f ( 2 , 31)=3.66 , p=0.038 ] . a post - hoc bonferroni analysis showed that hyperarousal was significantly greater in t2 than in t1 ( p<0.044 ) . yet , as it can be shown in table 2 , the overall scores for each subscale were , in general , very close to the minimum possible level of severity . with regard to the assessment of the perceived importance of the event , a repeated - measures analysis showed a significant time effect for traumatic event [ f ( 2 , 32)=20.00 ; p=0.0001 ] . traumatic at baseline ( t1 ) than 5 months later ( t2 ) or 13 months later ( t3 ) ; there were no differences between t2 and t3 . mean scores of this variable were close to the maximum possible score both at t2 ( m=8.76 ) and t3 ( m=8.97 ) ( see table 2 ) . two additional anovas on the perception of life at risk and having a perception of severity did not show time effects . yet , participants perception of these two variables was remarkably different . mean score for life at risk was significantly lower than that of perception of severity at any time of measurement : t1 : [ t ( 31)=-3.45 ; p=0.002 ] ; t2 : [ t ( 32)=5.89 ; p=0.0001 ] ; t3 : [ t ( 31)=7.27 ; p=0.0001 ] . regarding the scores in the ghq12 , we ran a 3 x 2 anova ( time x positive / negative mental health ) , which only yielded significant results for the positive / negative factor [ f ( 2 , 33)=45.90 ; p=0.0001 ] . positive mental health scores were higher than negative mental health scores ( i.e. , general distress ) at any time of assessment : t1 : [ t ( 29)=7.06 ; p=0.0001 ] ; t2 : [ t ( 30)=5.19 ; p=0.0001 ] ; t3 : [ t ( 31)=8.35 ; p=0.0001 ] . in regard to positive and negative emotions , we ran a 3 x 2 repeated measures anova on the panas scores ( time x positive / negative affect ) , which only yielded a main effect for positive / negative affect [ f ( 16)=26.90 ; p=0.0001 ] . furthermore we found that the levels of positive affect were greater than those of negative affect in the three evaluations carried out at t1 [ t ( 31)=6.49 ; p=0.0001 ] , t2 [ t ( 18)=3.51 ; p=0.002 ] , and t3 : [ t ( 31)=8.37 ; p=0.0001 ] . finally , a series of one - way anovas on dispositional optimism ( i.e. , lot - r ) and optimism on a full recovery from the heart problem showed that there were no changes in scores of both measures across the three times of measurement [ f(2 , 29)=0.26 , ns and f ( 2 , 29)=0.73 , ns , respectively ] . furthermore , as can be seen in table 2 , scores on both types of optimism , as well as in the rest of measures of positive affect , were consistently high across time . as can be seen in table 3 , using a cut - off score of pcl - c>44 , the probable prevalence of significant stress reaction in t1 is very low , rising to a prevalence of 11.1% after 5 months . finally , the number of cases with probable diagnoses of ptsd declines 13 months after the event ( 3.1% ) . probable prevalence of ptsd based on a selected cutoff score for the ptsd checklist ( pcl - c ) and percentage of patients fulfilling criteria for each of the three symptom clusters in regard to the prevalence of specific syndromes ( see measures section ) , it was found that , at each point of measurement , re - experiencing was the criterion that appeared in the greatest number of participants while the criterion of avoidance was that of least prevalence in the patients evaluated ( table 3 ) . the progression of the three steps over time was similar : the moment at which most subjects met the criteria was at five months after the mi , while mitigating later . the sudden and brusque occurrence of a mi is a potentially serious and life - threatening condition . it is interesting that , during the first few days , the heart attack was not considered to be a highly traumatic event by the participants but , 5 months and 13 months after the mi , it was considered so . nevertheless , this perceived severity and the perception of the event as traumatic did not correspond to a grand estimation that one 's life was in danger . probably , the fact that the patient was treated rapidly and clinically stabilized in a safe , hospital environment , leads to a weakening of the perception of risk , which in turn can explain the relatively low prevalence of symptoms related to stress encountered in this study and in studies of similar design ( bennett et al . , it is likely that rapid medical intervention and hospitalization may prevent people from developing intense sensations of horror or despair , which can be considered a necessary prerequisite for the diagnosis of ptsd and a strong predictor of the severity of this condition ( brewin , andrews , & rose , 2000 ) . , it is more likely that these differences reveal that at t1 ( i.e. , only a few days after the event ) , mi patients may not have enough perspective to judge the medical and psychosocial consequences of the event . interestingly , contrary to other studies ( ginzburg et al . , 2003 ) , the high perception of the event as severe and traumatic did not correspond to a high level of ptsd in our sample . it is possible that this elevated perception of seriousness may be the result of the impact of the heart attack on other areas of functioning ( e.g. , work performance , physical and sexual activity , perception of disability , and limitations ) rather than the direct effects of the mi itself . in any case , the study reveals that the perception of the event can change significantly with the passing of time and it is necessary that clinicians be aware of this factor . one of the advantages of the design of our study was the ability to be able to make an immediate evaluation of the patient 's affective state during the first hours following the heart attack . in general we have found that there are no significant changes either in total symptomatology in the pcl - c or in patterns of symptoms related to the stress ( i.e. , re - experiencing and avoidance ) over time ( i.e. , 5 months and 13 months later ) . the only exception was a significant increase of hyperarousal from t1 to t2 , returning in t3 to its basal level . as changes in arousal are not a common clinical characteristic of mi ( thygesen , alpert , & white , 2007 ) , it is likely that the increases in hyperarousal detected in our sample are instead part of a psychological reaction in response to this serious medical condition . there were neither significant changes with regard to positive emotions nor optimism present from the onset . these positive emotions were significantly greater than the negative ones at all times of measurement , so it is not probable that the affective well - being that was observed from the first days after the event results from an effect of illusory optimism that has been described elsewhere ( zoellner & maercker , 2006 ) . it is possible that these positive emotions not only have an important role as buffer factors for negative emotions ( fredrickson , 2001 ) , but that they are also important for a better recuperation from the medical problem ( howell , kern , & lyubomirsky , 2007 ; vzquez , hervs , rahona , & gomez , 2009 ) . in the case of trauma - related disorders , recent investigations have made clear that positive emotions and cognitions are not necessarily absent ( fredrickson , tugade , waugh , & larkin , 2003 ; vzquez & hervs , 2010 ) . although there are few references to positive emotions in patients having suffered an mi ( affleck , tennen , & croog , 1987 ; brummett , morey , boyle , & mark , 2009 ) , the finding that these patients are capable of optimism and of feeling relatively intense positive emotions is important . in fact , there is growing evidence showing that resilience is mediated by a complex network of mediational cognitive and motivational processes ( lyubomirsky , 2001 ) in which positive emotions experienced during and after the trauma may have an important role in the attenuation of psychopathological problems ( vzquez & hervs , 2010 ) . the pattern of results of our study reveals that , in general , a myocardial infarct , with adequate medical treatment , has a relatively minor effect on the appearance of psychopathological symptoms related to post - traumatic stress . this corresponds also with the low prevalence of psychopathology found in previous studies ( ginzburg et al . , 2003 ; hari et al . , 2010 ) and even in medical problems such as cancer ( shelby , golden - kreutz , & andersen , 2008 ) . the results obtained with regard to the prevalence of probable cases of ptsd in our sample are consistent with those found in the literature . we found 11.1% of probable cases at 5 months from the mi and 3.1% at one year following the event . in similar studies , with first - time mi patients and with a comparable measurement period , for example , levels of ptsd of 9.8% are found at 6 months , ( shemesh et al . , 2001 ) . although it is difficult to compare our results with other longitudinal studies , due to the fact that none have three measurement periods , and none coincide with regard to the time between measurements , published studies usually show this decrease in the prevalence of ptsd over a period of time ( ginzburg et al . , 2003 in a more general manner , the findings of our study corroborate that most people show resilience in adverse situations ( wessely , 2004 ) . studies of the general population indicate that whereas traumatic events , as defined in dsm - iv , may affect more than 50% of the general population in the course of their lives ( breslau , davis , & andreski , 1995 ; darves - bornoz et al . , 2008 ) , only 13% ( 515% , if the less severe forms are included ) will show ptsd ( alonso et al . , 2004 ; kessler et al . , 1995 ) . in the case of physical illnesses , the european study of the epidemiology of mental health showed , in a sample of 8,796 subjects from the general population , that while 10% of the sample had suffered a serious illness , only 2% of these patients had developed ptsd as a result of that illness ( darves - bornoz et al . , 2008 ) . the study , nevertheless , has some limitations . in the first place , although the initial number of participants was relatively high , various conditions ( including a high death rate ) decreased the resulting final sample . however , as has been explained above , the analyses revealed that the final samples of the study in t2 and t3 did not differ significantly from the initial sample either in socio - demographic ( age , sex , socio - economical level ) or psychopathological variables . secondly , it is possible that the evaluation of the symptoms related to post - traumatic stress could have been better dealt with using structured diagnostic interviews . we chose the pcl - c as it is a relatively efficient instrument to carry out a diagnosis of probable ptsd although it takes into account only the symptom criteria of dsm - iv - tr ( i.e. , symptom clusters b , c , and d ) . nevertheless , our results are similar to those obtained in other studies that have employed this style of questionnaires ( van driel & op den velde , 1995 ; rocha et al . , 2008 ) . we wish to stress that , in t1 , the results of the plc - c inform only of symptoms related to stress , as less than a month had passed since the appearance of the cause of stress . the sole study that has evaluated patients so soon after the mi was that of ginzburg et al . ( 2003 ) who , 4 days after the mi , evaluated the the presence of probable acute stress disorder by using a questionnaire ( cardena , 1996 ) . in any case , our investigation shows that one must be cautious with regard to the pyschopathological implications of important physical conditions . the sufferance of a severe and unexpected physical condition does not guarantee the appearance of symptoms related to the trauma . therefore , it is necessary to be very cautious in the use and abuse of the term trauma to characterize common medical problems even when they may be potentially life - threatening . there is no conflict of interest in the present study for any of the authors .

background there is a controversy as to whether the diagnostic umbrella of post - traumatic stress reactions is directly applicable to serious health conditions like myocardial infarction ( mi).objective the principal objective of this study was to examine longitudinally the prevalence of posttraumatic stress - related symptoms , throughout three measurement periods , for patients who had suffered a first mi . in addition to the analysis of symptoms related to stress and general distress , the presence of and temporary evolution of positive emotions and optimism in these patients was also evaluated.design a longitudinal study with three periods of evaluation after the mi ( time 1 ( t1 ) : 4872 hours , time 2 ( t2 ) : 5 months , and time 3 ( t3 ) : 13 months ) . results in t1 few symptoms related to the stressful event were found . the probable prevalence of ptsd was 811% at 5 months after the mi and 03% 13 months after the event . with regard to subjective severity of the infarction , although in the first instance patients did not regard the event as excessively traumatic , in the periods t2 and t3 this perception increased significantly [ f ( 2 , 32)=20.00 ; p=0.0001 ] . at all times during the measurement period the mean positive affect was significantly greater than the negative affect . conclusions as the results show , the probable prevalence of ptsd , as well as the severity of different symptom clusters , is low at all times of the evaluation . the diagnostic implications of these findings are discussed as well as the uses and abuses of diagnostic labels to characterize the psychological experiences lived through after a potentially life - threatening health problem .

By 1992, three years after he left the White House, Ronald Reagan was anything but a beloved former president. As a painful recession gripped the country, the public came to see the Reagan years -- which featured a massive defense buildup, soaring deficits and even a stock market crash in 1987 -- as the source of their economic woes. Running for president that year, Bill Clinton promised to enact a clean break from the "failed policies of Reagan and Bush." As Reagan prepared to speak at the Republican National Convention in August, a Gallup poll found that just 46 percent of Americans had a favorable view of him. By contrast, Jimmy Carter, the man Reagan had defeated in a 44-state rout in 1980, was viewed favorably by 63 percent of the American public. The Reagan presidency stood in something approaching disrepute. Today, though, you'd never know any of this happened. In the two decades since it bottomed out, Reagan's image has been resurrected, thanks largely to a relentless campaign from conservative activists. Will Bunch, who writes for the Philadelphia Daily News and is a senior fellow at Media Matters, chronicled Reagan's image makeover -- and the reality of his record as president -- in his 2008 book "Tear Down This Myth." We spoke with him recently about how the myth of Reagan has taken hold, and whether there's any truth to it. I'm really struck by the poll that showed Carter much more popular than Reagan. It's not something that people would think is possible if you asked them now. Can you talk about how we reached that point, back in the early '90s? By 1992, Reagan and Carter were kind of being compared as ex-presidents, and on a lot of levels, Jimmy Carter has had this very successful ex-presidency with the work he's done for Habitat for Humanity and from the other peace-oriented types of missions he's been on around the world. Reagan received an enormous amount of criticism a couple of years after he left office, particularly for an episode that's probably not going to get mentioned a lot this week, which is accepting, I believe it was $2 million, to give a speech in Japan. At the time, it was unusual and kind of jarring for Reagan to accept that much money to give a speech, plus the fact that a bunch of millionaires in California had all chipped in to buy Reagan a house, which a lot of people thought was kind of suspicious and didn't look too different from bribery. Also, Nancy Reagan actually published her memoirs (1989's "My Turn"), and they were very poorly received as being kind of nasty and vindictive. And so there were a lot of negative feelings about Reagan. But the real reason Reagan had fairly high unpopularity in the early 1990s was that people were not happy with the aftermath of his policies as president. The American economy was doing very poorly in the early 1990s, there was a recession during the presidency of George H.W. Bush. Bush 41's presidency basically collapsed because he was forced to increase taxes to deal with the continuing deficits that were a legacy of Reagan. There was high anxiety among the American people starting in Reagan's second term about the loss of jobs in manufacturing, the growing clout of Asia -- so all of these things really caused Reagan to be viewed pretty negatively at the time. Bill Clinton campaigned very aggressively against Reaganomics. When Clinton was able to get some of his economic policies through Congress in the first two years of his presidency, Time ran a cover with a picture of Reagan upside down, and it was about the death of Reaganomics. That was the tone in the early '90s, before this conservative campaign to build what I call the Reagan myth got started. Going back a step to his time in office, the popular version of Reagan's presidency is that he was elected kind of overwhelmingly, and then in 1984 reelected in a 49-state landslide, and then he just rides off into the sunset at the end of his term. But that second term was -- there were some serious problems in there, weren't there? Oh, absolutely. A lot of people -- and I mean people in Congress who were in a position to do something about it -- felt that Reagan possibly committed impeachable offenses in the Iran-Contra scandal. There were several reasons he wasn't impeached. One, I think, was his age and some concern about his mental state, and the fact that he was in his second term. You have to remember that in the late 1980s, it really didn't feel like it was that long after Watergate -- and I think there's a tendency in politics to not want to relive something that's so traumatic. I mean, obviously, Congress had shed its qualms about impeachment by the late 1990s, but I think with Reagan there was a reluctance to do that. Reagan's poll numbers really suffered a lot in the last two years of his presidency, partly because of Iran-Contra, but the other thing was the huge crash of the stock market in October 1987, which in the short run caused people to really start to reexamine Reagan's economic policies and whether the economic boom of the mid-1980s had maybe been a house of cards. I believe there was a poll that showed maybe a third of the American people wanted to see Reagan resign before his term was over, and certainly his approval ratings fell back under 50 percent. The thing about Reagan and his approval ratings is they really went way up and way down. I mean, he was elected by a pretty big margin in 1980, probably because of Jimmy Carter's unpopularity. Then, when he came into office, he cut taxes and always gets so much credit for improving the economy -- except the economy got much worse over the next year, to where unemployment hit a high point, I think 10.8 percent. And Reagan's approval ratings dropped much lower than Obama's ever has, down to 35 percent. And then in '84 -- talk about good timing -- he really got the most benefits of the inevitable capitalist cycle of the reversal of the economy. It was really roaring back in '84, and the Democrats didn't really nominate the strongest opponent in [Walter] Mondale, and Reagan did win a big landslide. But then his popularity really plunged again because of Iran-Contra and nagging worries about aspects of the economy. When he left office, his approval ratings were pretty high, and I think that after all the failed presidencies that came before him -- Nixon, Carter and Ford -- there was a sense of relief that he'd gotten through two terms and nothing disastrous had happened. There was goodwill toward Reagan because of his personality and his age. So he left office with a pretty high approval rating. And when he left office and people started to ponder the effects of his policies, his poll numbers dropped again only to be resurrected in the late 1990s. But here we are just 15 or 20 years later and that whole story you just outlined is forgotten by so many people. What was the turning point from, say, that summer of '92, when Carter was actually more popular than Reagan, to where we are today? There was always an effort on the right, starting from 1989 on, to try to give Reagan credit for winning the Cold War. The funny thing was, at first the public didn't really buy into that because the public was following the day in and day out of the news very carefully and felt what I think most scholars feel, which is that the credit for the Soviet Union collapsing largely belongs to Mikhail Gorbachev -- that it was Gorbachev pressing for these reforms and Reagan was an external force that wasn't quite as important. I quote in "Tear Down This Myth" a USA Today poll that was taken after the Berlin Wall collapsed (in October 1989) and a majority of Americans credited Gorbachev and only 14 percent credited Reagan. How the myth gets started is that memories get softer and you have one group that gets very aggressive in pushing this notion that it was all Reagan's doing, that it was because of his defense buildup. The other thing is, during the 1990s, it was a great time economically -- probably better than it should have been because of the dot-com boom. At least among one class there was a lot of affluence in America -- and there were improvements that reached down to lower income. Black unemployment, for example, dropped during Clinton's presidency. It created this feeling that America had been on a roll and people forgot the recession of the early 1990s and how bad things had been and their anger with Reagan. They were more willing to say, "Well, this all started with Reagan," forgetting all those bad things that happened in the '80s and '90s. It's no accident that the push to glorify Ronald Reagan started in 1997, because it was the year that Bill Clinton started his second term. He had just defeated Bob Dole overwhelmingly and things looked bleak for the broader conservative movement. They didn't seem to have anybody on the horizon to be a leader of the party, so there was this very conscious and calculated effort to look back. Something else that you can't overlook is that in 1997 Reagan was still alive and he announced with a lot of class and dignity in 1994 that he had Alzheimer's, so the public hadn't actually seen Reagan for three years. And the public impression of Nancy Reagan softened quite a bit, for good reasons -- she was out there pushing for stem cell research and other things. It would have been very difficult to criticize Reagan because of his health, a situation that engendered personal goodwill. And that was something else conservatives could use as they launched this campaign to build up the Reagan legacy. They call it the Ronald Reagan Legacy Project, started in 1997 by Grover Norquist. It was this aggressive push to rename as many things as possible across the country for Reagan. It started with the airport in Washington, which they successfully renamed Reagan Airport. And it's funny to see news from that time, because a lot of Democrats were biting their tongues because they had no good memories of Reagan's presidency, but because of his health nobody was going to vote against renaming the airport for Reagan. Not all of the ideas have been enacted. We still don't have Reagan's picture on a $50 bill, or alternating on the dime with FDR, as some people proposed. But there are an increasing number of Ronald Reagan statues across the country, and you can almost drive across the Sun Belt continuously on some sort of Ronald Reagan boulevard or freeway or highway. Not surprisingly, the push to rename things for Reagan has been more successful where conservatism is the most popular. It seems that a lot of people aren't even aware of what Reagan actually did as president, and you can point out areas where he clearly didn't do things that you would call conservative -- immigration comes to mind, with the amnesty in 1986. Do the Reagan deifiers even know what they're worshiping? Especially now that Reagan's passed away, I think they're able to purport this idyllic, mythological version of Reagan who happens coincidentally to support all the pillars of the modern conservative movement. Political movements need a hero and Ronald Reagan -- the word "roles" is often associated with him because of his acting career, and his final role has been hero. But to do that, this movement had to do a rewrite, and things like the amnesty for undocumented immigrants had to go to the cutting room floor. He increased taxes on a number of occasions, either to undo the damage of his first tax cut, or because -- unlike modern conservatives -- he would actually engage in negotiations and try to compromise with Democrats on certain issues. All these things get lost because they don't fit the storyline that they're trying to push out there. What goes through your head when you hear conservatives talk about Ronald Reagan now? Well, I think they're misusing Reagan to push policies that in 2011 are destructive and could continue to be destructive to America. The whole tax thing is kind of insane -- that you can never raise taxes, which is not anything like what Reagan actually did. Even when he was governor of California, he actually signed the biggest tax increase that the governor of any state had ever signed at that time. So Reagan never subscribed to the idea that you can never raise taxes. The other thing that really rang true in the Bush years is using the great sound bites Reagan produced -- like "tear down this wall" or "evil empire" -- to justify things like the war in Iraq. I don't know if you saw "The Social Network," but there's a line in it about how every good creation myth needs a devil. Does this help explain why, just as Reagan's popularity has gone up in the last two decades, Jimmy Carter's has taken a hit? Is he a casualty of the creation of the Reagan myth? Yeah. The issue that was really the centerpiece of Carter's presidency was energy -- trying to promote useful alternative energy. And I don't see how you can look at what's happened over the last 25 years and not say that Carter was right: that we should have been researching alternative energy the whole time, and as a result we've fallen behind other countries; that we're addicted to oil and unable to shake that. But if you listen to talk radio, Jimmy Carter is reduced to wearing the sweater and turning the thermostat down at the White House. They've done such a good job creating Carter as kind of an anti-Reagan -- that part of Reagan's greatness was that he saved America from the malaise, which, by the way, is a word that Carter never actually uttered. This has become the modern equivalent of waving the bloody shirt was for the post-Civil War Republicans: waving the Jimmy Carter cardigan sweater. ||||| Today, November 4, marks the thirtieth anniversary of Ronald Reagan’s election as president. It is a fitting time to dispense once and for all with the myth that there is any similarity whatsoever between Ronald Reagan and Barack Obama. Washingtonians and insecure politicians obsess with comparisons but can anyone imagine Lincoln or FDR or JFK or Reagan comparing themselves to previous presidents? Far too secure in their own skin, they enjoyed the presidency as Kennedy said paraphrasing the ancient Greeks that it was "the full use of your powers along lines of excellence." ADVERTISEMENT ADVERTISEMENT Fellini said, "you must live spherically" and by this, the old movie director meant one should live their lives in many different directions. Reagan was a star athlete and a good student and a class president at Eureka College and a captain of the swim team there. He was a successful radio broadcaster, favorite movie actor and a six term union president and host of GE Theatre (one of the most popular shows on television all through the 1950's) and a lecturer and a writer and a governor and a political leader and a rancher and a carpenter and horseman and devote Christian and doting father and loving husband and good friend. He did all these things before becoming the 40th president of the United States and then when he did, he revived a moribund country, resuscitated a dead economy (far worse than Obama's) and then conquered an Evil Empire, freeing millions imprisoned behind the Iron Curtain. He did all these things because he believed and lived American Exceptionalism. And then he rode off into the sunset, never worrying about his post-presidency as a means of cleaning up the mess of his time in office. He left no mess but instead, the country and the world much better off than he found it. Reagan's legacy didn't need to be rehabilitated. After all, his approval rating in January of 1989 was 70 percent. Among voters under 30, it was a mind boggling 85 percent! Barack Obama, on the other hand, is our first "Facebook" president. He wrote two autobiographies before he was elected. His only world knowledge is in the study of himself which explains his preferred personal pronouns of "I" and "Me" and "My." He is a product of his generation and has never risen about his utterly self-absorbed culture. Reagan was derided by the elites all the time he was in Washington as some kind of unsophisticated dummy but in fact was an extraordinary well-read man, having developed his own singular and unique ideology, based on the individual. He arrived at this as a student of the Enlightenment, of faith and of populism. Thomas Paine was his favorite philosopher and embraced the "Natural Law" of man's freedom associated with him and his peers of the time. Yet Reagan also embraced the faith-based belief that God's plan for Man was freedom as well as the populism of Andrew Jackson, who understood innately that the only system that worked must include, as Reagan said, "maximum freedom consistent with law and order." One is hard pressed to believe that Obama thinks such thoughts though simpering elitists like Paul McCarthy have bought into the hype and propaganda about Obama. Can anyone recall Obama ever quoting a Founding Father or a great philosopher? Reagan quoted the Roman Emperor Diocletian. Diocletian! Of more immediate concern are the incessant comparisons between 1982 and 2010. In fact, there is no comparison, mainly because even though Reagan's popularity had sagged and support for Reaganomics had fallen, when pressed, in all the polling data, the American people still believed in Reagan's prescriptions. Today, the American people don't believe in Obama's plan and by overwhelming numbers, too, oppose everything he has sponsored over the past two years. After 1982, Reagan didn't need to "move to the left." He stuck to his guns by staying the course, the theme of that off-year election. Is anyone urging Obama to "stay the course?" Reagan's plan eventually came to fruition beginning in January of 1983 when the economy created one million new jobs. The Washington Post thought this was so significant, it was not even reported in the front section of the paper, let alone the front page. His plan resulted in 96 months of unbroken economic growth, the creation of 18 million new jobs, the eradication of inflation and high interest rates and, to boot, non-defense federal spending fell by nearly 14 percent on his watch. He also used the veto pen more than any president since Ike. Let's see if Obamanomics creates one million new jobs next January. Just like Reagan? Oh, please. Craig Shirley is president of Shirley & Banister Public Affairs and has written two books on Ronald Reagan, including his newest, "Rendezvous With Destiny" (Intercollegiate Studies Institute, 2009). He is now working on a third Reagan book and a political biography of Newt Gingrich.

– Republicans sometimes bristle at the comparisons between Ronald Reagan and Barack Obama because of their midterm troubles. A favorite conservative theme about Reagan is that the "love fest" between him and the American people continued during and after his presidency, writes Steve Kornacki at Salon, who singles out this piece as an example. He says it's time for a reality check. He ticks off the Savings and Loan mess, the Iran-Contra scandal, and a national debt that tripled to $3 trillion. George HW Bush suffered for the sins of Reagan, to the point where Bill Clinton was able to steal the "Reagan Democrats" back. Polls in 1992 found that just 24% of Americans thought the country was better off because of Reagan, and his popularity sank below Jimmy Carter's to 46%. His image has since been restored, but "the conservatives who lionize Reagan today are worshiping a flattering caricature," he writes.

a great deal of progress has been made in the last decade in the studies of distant galaxies . the average star formation history of the universe has also been estimated from emission properties of galaxies detected in deep imaging and redshift surveys such as the canada - france redshift survey and the hubble deep field ( e.g. , lilly et al . 1996 ; madau et al . 1996 , 1998 ) . a large population of bright galaxies with high star formation rates ( sfrs ) has been uncovered by means of the lyman - break technique ( e.g. , steidel et al . . however , such flux - limited studies may not be adequate for investigating the evolution of normal galaxies , since such studies are biased toward the brighter or the more actively star forming galaxies . in principle , a less biased sampling of distant galaxies may be obtained by means of the absorption lines they superpose in the radiation from background quasars . the presence of heavy - element absorption lines in quasar spectra preselects regions that have undergone some degree of star formation . there is nothing special about the lines of sight to the absorbers except for the convenient placement of background quasars , assuming that most of the absorbers are intergalactic material and not ejected material near the qso at high , special relativistic velocities . thus , it is very likely that these absorbers are surrounded by other galactic or protogalactic objects at the same redshifts . thus in principle , deep images of quasar absorber fields may reveal star - forming regions at high redshift . since a well - known signature of star forming galaxies is strong ly-@xmath0 or h-@xmath0 emission , a natural strategy to look for the absorber galaxies or their companions is to search for the redshifted emission lines . several previous studies have attempted to detect continuum and line emission from galaxies underlying quasar absorbers . at low redshifts , [ o ii ] or [ o iii ] emission has been detected in mg ii systems with narrow - band imaging ( e.g. , yanny 1990 ; yanny , york , & williams 1990 ; bergeron & boisse 1991 ; yanny & york 1992 ) . searches for low-@xmath9 damped lyman - alpha absorbers ( dlas ) have often imaged , and sometimes spectroscopically confirmed , galaxies with various morphologies ( spirals , irregulars , low surface brightness galaxies etc.e.g . , steidel et al . 1994 , 1995 ; lebrun et al . 1997 ; bowen et al . 2001 ; cohen 2001 ; turnshek et al . 2001 ) . at high redshifts , however , it has been much more difficult to identify and study in detail the galaxies responsible for quasar absorption systems . there have been a few detections of ly-@xmath0 emission in quasar absorber fields ( e.g. lowenthal et al . 1991 ; francis et al . 1996 ; roche , lowenthal , & woodgate 2000 ) . however , most other attempts to detect ly-@xmath0 emission from high-@xmath9 intervening ( @xmath10 ) dlas have produced either non - detections or weak detections ( e.g. smith et al . 1989 ; hunstead et al . 1990 ; lowenthal et al . 1995 ; djorgovski et al . most of the few confirmed ly-@xmath0 detections for high - redshift dlas have been for absorbers with @xmath11 , which may differ from the cosmologically more interesting general population of dlas with @xmath10 ( e.g. warren & moller 1996 ; moller & warren 1998 ; fynbo et al . 1999 ) . most attempts to detect dlas in h-@xmath0 have either yielded non - detections or detected objects separated by large angular distances from the quasars , rather than objects close to quasar sightlines ( see , e.g. , teplitz , malkan , & mclean 1998 ; bechtold et al . 1998 ; mannucci et al . 1998 , bunker et al . these objects , while unlikely to be the absorbing galaxies themselves , are still interesting because they are likely to be companion galaxies in the same cluster as the absorber . a summary of previous attempts to detect high-@xmath9 dlas in emission is given by kulkarni et al . ( 2000 ) . with the goal of obtaining a large sample of sfr estimates in the fields of high - redshift absorbers , we have started a lyman-@xmath0 imaging survey for absorbers at @xmath12 using a fabry - perot imager as a tunable narrow - band filter . here we report our results for six fields with known heavy - element absorption systems . sample selection , observations , and data reduction are described in section 2 . the reduced images and photometry are presented in section 3 . section 4 presents a comparison of our results with previous studies of the same fields and with results of other ly-@xmath0 emitter studies . section 4 also compares the sfr constraints from our study with the estimates from other emission - line searches for quasar absorber galaxies . a comparison with predictions based on global sfr models is also presented . the blue and vis - broad etalons in the goddard space flight center ( gsfc ) fabry perot ( fp ) imaging system have optimum sensitivity and resolution in the wavelength range @xmath13 . we therefore restricted our search to the redshift range @xmath14 . we searched the york et al . ( 1991 ) catalog of heavy - element quasar absorbers for absorbers with ( i ) @xmath15 ( ii ) @xmath16 to avoid absorbers possibly associated with the quasars , and ( iii ) with well - detected mixed ionization species ( si ii , al ii or o i in addition to c iv and/or si iv ) . six such objects were finally observed . two of these six systems are dlas , and one is a sub - dla . in addition to these six systems , we also observed the well - studied field of the radio galaxy 53w002 containing ly-@xmath0 emitters at @xmath17 ( pascarelle et al . 1996a , 1996b ; keel et al . 1999 ) , as a calibration object . table 1 lists the general properties of the objects observed . the fp instrument used for our observations has a choice of six queensgate 50 mm diameter piezo - electrically driven , capacitance - stabilized etalons which can be tuned to any wavelength in the range 4000 - 10000 , and with resolution from 2.5 to 28 fwhm depending on the etalon and the wavelength . the system throughput including the ccd is 20% in the red and 5% in the blue . the instrument is used at the nasmyth f/10.3 focus of the apo 3.5 m telescope . behind the telescope focus a field lens and collimator lens collimate the light through the etalon and an order - sorting blocking filter , and a camera lens refocuses onto the ccd . the camera has a stis technology site 2048x2048 ccd with 21 @xmath18 m pixels , 5 e@xmath19 rms readout noise , mpp ( inverted operation ) , minichannels , and a very high efficiency down to 3400 . the quantum efficiency is 82% at 4000 , 90% at 7000 and 53% at 9000 . this provides a large field of view , low noise , smooth bias levels , high charge transfer efficiency , and high sensitivity with uv , visible and ir etalons . the instrument can be controlled from the observatory control room via the apache point fiber optics communication system , or remotely over the internet , using command line control and a vnc gui monitoring system . the wavelength transmitted by an fp system is a function of the field angle . @xmath20 $ ] , where @xmath21 is the camera lens focal length , 200 mm , and @xmath22 is the distance on the detector from the optical axis . at the apo f/10.3 nasmyth focus , @xmath23 \biggr\}$ ] , with @xmath24 in arcseconds on the sky . for example , for @xmath25 = 4100 , @xmath26 , @xmath27 = 11.1 . the effective monochromatic field of view depends on the tolerable fraction of the spectral width . table 2 lists the details of our observations . the observations were carried out primarily with the blue etalon during 9 runs between october 2000 and may 2004 . the seeing varied between 1.0@xmath28 and 1.8@xmath28 fwhm . conditions were not photometric for many of the nights . the narrow - band exposures were obtained setting the fp to the air wavelengths of the expected ly-@xmath0 emission lines at the absorber redshifts . in some cases , additional narrow - band exposures were also obtained with the vis - broad etalon at wavelength settings offset by 400 km s@xmath5 redward of the absorber redshifts . the wavelength calibration was checked throughout using scans of lines from an ar lamp . a temperature control program was run throughout to automatically keep the fp wavelength setting fixed by correcting for effects of temperature variations every five minutes . the fwhms for the different fields were 5.6 - 14.7 , as measured from the width of the calibration lamp lines . a @xmath29 binning was used , resulting in a plate scale of 0.366 @xmath28 per binned pixel . the full circular field of view corresponds to @xmath30 in diameter . of course , given the variation in the central wavelength as a function of angle from the axis , the central @xmath31 diameter region is sampled within @xmath32 km s@xmath5 of the central wavelength expected at the absorber redshift at 4100 . total narrow - band integration times were 320 - 600 minutes per field , split into 8 - 15 exposures of 40 minutes each . in addition , b - band exposures were obtained for all fields to sample the uv continuum near the ly-@xmath0 line . a pentagonal dither pattern was used to aid with flat - fielding and cosmic ray removal . twilight sky flats were obtained for each wavelength setting . standard star exposures were obtained for hz44 . additionally , images of the 53w002 field were also used for photometric calibration . data reduction was carried out using standard iraf tasks . the biases on each night were combined to get an average bias frame . the darks , flats and the object frames were corrected for the overscan region using the ccdproc task . all the images were trimmed to a size of 561 x 561 pixels or @xmath33 , which contains the full field of view of the fabry perot . the darks , the flats and the object frames on each night were bias - corrected with the average bias corresponding to that night . the flat frames and the object frames were then dark - corrected with the combined dark for each night . the flat frames were combined using the flatcombine task to produce average flats corresponding to different wavelengths and filter settings . in some cases , twilight or dome flats were not available for a particular wavelength and filter setting . in such cases , dark - corrected object frames were combined ( with all objects removed ) to create an average sky flat that was later used for flatfielding . object frames for a particular wavelength and filter settings were flat fielded using the average flats in the same setting . bias , dark and flat frames from other nights in the same season were used in a very few cases where they were not available on the same night . the iraf task cosmicrays was used to remove cosmic rays from each object frame . a bad pixel mask was created for each image and the bad pixels were removed using the iraf tasks ccdproc or fixpix . to account for the varying degrees of extinction encountered over different nights , we carried out an empirical correction . the flux counts for unsaturated bright stars were measured in each image using the phot task in iraf . the counts were corrected for images with different exposure times . for each star , the maximum value of counts @xmath34 from different images was taken as an indicator of the unextinguished flux level of the @xmath35th star . the flux ratio for the @xmath35th star in the @xmath36th image @xmath37 was then calculated for the best four or five stars in all images to estimate the extinction factors . the extinction factors thus derived for these four or five stars in each given image were then averaged to get an indication of the extinction for that image . finally , each image was multiplied by this average empirical extinction factor to get an extinction corrected image . all extinction - corrected images for each field and filter / wavelength setting were registered and shifted so as to match the coordinates of a reference star in all frames . this was done using the imexam , lintran and imshift tasks . some images were rotated using the geomap and gregister tasks to match the coordinates of all stars in different images , to correct for a small rotational offset between some images taken at the same pointing in different observing seasons . finally , the individual exposures for a given object and given wavelength and filter setting were combined using the iraf task imcombine to get the final narrow - band and broad - band images . figures 1(a)-6(a ) show @xmath38 sections of the reduced broad - band ( b ) images of the quasar absorber fields of q0216 + 080 , q0636 + 680 , q0956 + 123 , q1209 + 093 , q1442 + 101 , and q2233 + 131 , respectively . the corresponding panels ( b ) show the narrow - band images of the same fields obtained with the blue etalon . the stripes at the borders of some images are an artifact of the coadding of the dithered images . the quasar is absent or considerably dim in the narrow - band images for q0216 + 080 , q1209 + 093 , and q2233 + 131 since the absorbers being studied in these systems are dlas or sub - dlas . figure 7 shows the calibration field 53w002 . the expected b - band continuum must be subtracted from the observed narrow - band fluxes in order to determine if a statistically significant redshifted ly-@xmath0 excess exists for any object seen in both bands . we estimated the continuum in the narrow - band images by scaling the b images using the relative photometric calibrations of the two images . to do this , we subtracted a scaled b band image from the narrow - band image , aligning the images spatially , and adjusting the scaling factor so as to minimize variance in the central portion of the subtracted image . furthermore , to minimize the effect of different seeing in the broad - band and narrrow - band images , the broad and narrow - band images were convolved with a gaussian of the same fwhm before subtraction in idp3 . the subtraction was carried out interactively , using the interactive data language ( idl , version 6.1 ) program image display paradigm-3 ( idp-3 ) version 2.7 , written by d. lytle and e. stobie ( see , e.g. , lytle et al . 1999 ) figs . 1(c)-7(c ) show the resultant continuum - subtracted images for the six quasar absorber fields and the calibration field of 53w002 . finally , figs . 1(d)-7(d ) show @xmath39 close - up views of the continuum - subtracted images . all of the objects in the narrow - band images disappeared almost completely after subtraction of the continuum . the slight residuals left at the positions of some objects arise because of the difficulty in matching the point spread functions ( psfs ) perfectly in the broad and narrow - band images . no significant ly-@xmath0 emission at @xmath7 level was detected from any object in any of the quasar absorber fields . the few vis - b images obtained for three of the fields ( q0216 + 080 , q0636 + 680 , q2233 + 131 ) were also analyzed in a similar manner , and showed no ly-@xmath0 detections either . no significant objects were found even if the images were smoothed using gaussian filters of about 2.5 or 5 pixels fwhm . finally , we also compared our images with broad - band images from the sloan digital sky survey ( sdss ) where available . a few very faint features are seen in our images for q0216 + 080 , but these features are indistinguishable from the noise . in q0636 + 680 and q0956 + 123 , some residual flux is seen close to the quasar after continuum subtraction . however , these regions close to the quasars are not well sampled at our modest angular resolution . thus , it is not clear whether the residuals seen near q0636 + 680 and q0956 + 123 are significant features or artifacts , without obtaining higher resolution images of these fields . in the case of q0956 + 123 , the feature apparent near the left upper corner of fig . 3(d ) is an artifact arising from a residual multipixel cosmic ray event in a single narrow - band image . in the field of q2233 + 131 , three bright galaxies are seen : 17.4@xmath28 east and 1.7@xmath28 south of the quasar ; 28.2@xmath28 east and 51.7@xmath28 south of the quasar ; and 35.2@xmath28 east , 30.2@xmath28 north of the quasar ( fig . all of these galaxies are seen in the sdss . however , all of these galaxies are far too bright to be at @xmath40 ( @xmath41 respectively from sdss ) . it is more likely that the excess emission seen in these objects is [ o ii ] @xmath42 emission from interloper galaxies at @xmath43 . we plan to obtain spectra of these galaxies in the near future to determine their redshifts . to estimate the limits on the ly-@xmath0 fluxes for the absorbers in our fields , we used our calibration observations of the field of the radio galaxy 53w002 . this field is known to have ly-@xmath0 emitters at @xmath44 ( pascarelle et al . 1996a , 1996b ; keel et al . 1999 ) . for calibration purposes , we used the brightest objects seen in our continuum - subtracted narrow - band images of this field , i.e. , objects 3 and 1 of keel et al . ( 1999 ; table 2 ) , labeled o1 and o2 in the bottom panel of figure 7 . aperture photometry of these two objects was carried out using the iraf task phot with aperture sizes @xmath45 times the seeing fwhm . using the ly-@xmath0 fluxes for these from table 2 of keel et al . ( 1999 ) and the counts measured for those objects in our images , we estimated the photometric calibration of our images . to correct for sensitivity differences at the different wavelengths used for our quasar absorbers and the calibration field 53w002 , we used our observations of standard star hz44 . using the photometry of this star in images obtained at the different wavelength settings , and adopting the absolute spectral distribution of this star from oke ( 1990 ) , we estimated the relative sensitivity differences of the fp at the different wavelengths . we next estimated the noise level in the continuum - subtracted blue - etalon images for each field . to do this , we considered a @xmath46 region centered on the quasar and determined the noise profile over this region using idp-3 . while doing this , we disregarded a circular region centered on the quasar with a radius of roughly twice the seeing fwhm to avoid effects of imperfect seeing matches between the broad and narrow band images . we then measured the mean noise level per pixel in concentric annuli of radii ranging from 2 times the seeing to 5 @xmath28 , and finally corrected for the sensitivity differences at the various wavelengths . the noise level per pixel was found to be nearly constant everywhere ( within a few @xmath47 ) in this region . the mean value of the noise per pixel was used to estimate the noise level per 2 pixel x 2 pixel region , assuming poisson statistics . based on this , we estimated the 3 @xmath2 observed - frame ly-@xmath0 point source flux sensitivity reached in our images . if dust attenuation is assumed to be small , these ly-@xmath0 flux limits can be converted to limits on the star formation rates ( sfrs ) . these point - source sfr limits implied by the non - detections of ly-@xmath0 emission in our quasar absorber fields are listed in table 3 and are in the range of 0.9 - 2.7 m@xmath48 yr@xmath5 . here , we have used the prescription of kennicutt ( 1998 ) for converting h-@xmath0 luminosity @xmath49 to the sfr , i.e. , @xmath50 and assumed a ratio @xmath51 for case - b recombination . we also used our continuum - subtracted images to estimate the flux limits for a diffuse foreground absorbing galaxy . to do this , we used the mean value of the noise per pixel to estimate the flux limit over the entire 10 @xmath52 region . this flux limit was used to calculate the limiting ly-@xmath0 luminosity and hence the limiting sfr in the @xmath53 region . at @xmath54 , this region corresponds to a size of @xmath55 kpc@xmath56 centered on the quasar , for the comsology adopted here . the diffuse - source flux limits are in the range of 2.6 - 7.4 @xmath57 erg s@xmath5 @xmath6 summed over the @xmath53 region . the corresponding summed sfr limits are in the range of 12.3 - 36.4 m@xmath48 yr@xmath5 over the entire @xmath53 region . for most of our targets , no other imaging information exists in any waveband on a scale comparable to our fields of view . for q0216 + 080 and q2233 + 131 , hst nicmos h - band images are available ( warren et al . the nicmos images of q0216 + 080 show two objects with @xmath58 and 24.34 , located 1.4@xmath28 and 3.8@xmath28 away from the quasar , at position angles of -104.8 and 97.8 degrees east of north , respectively . however , the closer object is likely to be an artifact since it occurs on a diffraction spike . for q2233 + 131 , the nicmos h - band image revealed two objects with @xmath59 and 25.12 , located 2.8@xmath28 and 3.3@xmath28 away from the quasar , at position angles of 158.6 and 68.3 degrees east of north , respectively . of these , the former object has been identified with a lyman limit system at @xmath60 ( djorgovski et al . none of these objects are seen in our b - band or nb images . this could be because of the difference in angular resolutions of our study and the nicmos study . in either case , no information on star - forming emission - line objects is available from these broad - band images . the only additional emission - line constraints available are for q0216 + 080 and q2233 + 131 . the narrow - band imaging study of deharveng et al . ( 1990 ) found no ly-@xmath0 emitters in the q0216 + 080 field , placing a 3 @xmath2 upper limit of @xmath61 erg s@xmath5 @xmath6 on the ly-@xmath0 emission flux . our observations of this field have provided a ly-@xmath0 flux limit @xmath62 times tighter than that of deharveng et al . ( 1990 ) . for q2233 + 131 , our limit agrees closely ( within @xmath63 ) with that of lowenthal et al . ( 1995 ) . [ [ the - space - density - of - ly - alpha - emitters - comparison - with - other - studies ] ] the space density of ly-@xmath0 emitters : comparison with other studies ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ to understand whether the non - detections of ly-@xmath0 emitters ( laes ) in our fields are consistent with other surveys for ly-@xmath0 emitters , we now examine results from some recent lae searches . stiavelli et al . ( 2001 ) detected 58 lae candidates over a field of 1200 arcmin@xmath56 at @xmath64 . based on this , they deduced a completeness - corrected space density of 0.07 laes per arcmin@xmath56 with ly-@xmath0 fluxes above @xmath65 erg @xmath6 s@xmath5 . palunas et al . ( 2004 ) detected 37 absorbers in a 46 @xmath66 46 field of view . based on this , they derived the space density of laes to be 0.019 arcmin@xmath67 in a redshift interval @xmath68 at @xmath69 . these ( stiavelli et al . 2001 , palunas et al . 2004 ) studies imply 0.49 and 0.42 laes per arcmin@xmath56 per unit redshift , respectively . at @xmath70 , lae searches by rhoads et al . ( 2000 ) and malhotra & rhoads ( 2002 ) have found space densities of 4000 deg@xmath67 per unit redshift , i.e. 1.1 lae per arcmin@xmath56 per unit redshift . these other lae searches cover much wider fields of view , and larger redshift ranges @xmath71 ( wider filter bandwidths ) than our study . adopting a mean space density of 0.45 laes per arcmin@xmath56 per unit redshift at @xmath72 from stiavelli et al . ( 2001 ) and palunas et al . ( 2004 ) , and using @xmath73 as a typical redshift range covered by our study , one would expect @xmath74 absorber in our fields with effective monochromatic coverage of @xmath75 , if our fields were similar to the other lae fields . on the other hand , the lae searches of rhoads et al . ( 2000 ) , stiavelli et al . ( 2001 ) , and malhotra & rhoads ( 2002 ) are not selected by the presence of a quasar absorption system . the presence of a well - established heavy - element quasar absorber with mixed ionization implies the existence of a region that has had some star formation . at @xmath69 , our complete fields of view of about 3.4 diameter cover about 2.2 mpc@xmath56 around the absorbing sightline ( assuming @xmath76 , @xmath77 , and @xmath78 km s@xmath5 mpc@xmath5 ) . given the gradient in the central wavelength , the roughly monochromatic ( within @xmath32 km s@xmath5 of the absorber ) fields of view of about 2.1 diameter cover about 0.8 mpc@xmath56 around the quasar sightline . since the absorbing galaxy certainly must lie within this region , one might expect a higher lae density in our fields than that in a blind field . francis et al . ( 1996 , 2004 ) and palunas et al . ( 2004 ) did indeed find a number of laes in wide - field surveys surrounding a field with 3 sub - dlas . however , this region appears to be a filament with higher density than a typical field region . furthermore , the laes in this filament are separated from 2 of the 3 absorber sightlines by more than 2 in radius ( see fig . 4 of palunas et al . such objects would thus not be detectable in a field of view such as ours . thus , overall , the lack of laes in our observations are not inconsistent with the space density of laes found by other studies . we note , however , that detailed comparisons would require a full consideration of the luminosity function of laes since our observations reach fainter flux limits than many of the other lae searches . [ [ the - star - formation - rates - of - quasar - absorbers - and - their - companions ] ] the star formation rates of quasar absorbers and their companions ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ fig . 8 plots our sfr limits in the fields of quasar absorbers together with the results of other searches for ly-@xmath0 , h-@xmath0 , h-@xmath79 , [ o ii ] , and [ o iii ] emission in quasar absorber fields . the filled red triangles show our apo ly-@xmath0 limits , while the unfilled black triangles at @xmath80 show our limits from previous h-@xmath0 imaging with hst / nicmos ( kulkarni et al . 2000 , 2001 ) . other data are from yanny et al . ( 1987 ) ; yanny , york , & williams ( 1990 ) ; yanny ( 1990 ) ; hunstead et al . ( 1990 ) ; deharveng et al . ( 1990 , 1995 ) ; giavalisco et al . ( 1994 ) ; lowenthal et al . ( 1995 ) ; francis et al . ( 1996 ) ; warren & mller ( 1996 ) ; bergvall et al . ( 1997 ) ; mannucci et al . ( 1998 ) ; teplitz et al . ( 1998 ) ; bunker et al . ( 1999 ) ; fynbo et al . ( 1999 , 2000 ) ; bouche et al . ( 2001 ) ; van der werf et al . ( 2000 ) ; mller et al . ( 2002 ) ; meyer , thompson , & mannucci ( 2003 ) ; mller , fynbo , & fall ( 2004 ) ; christensen et al . ( 2004 , 2005 ) ; schulte - ladbeck et al . ( 2004 ) ; chen , kennicutt , & rauch ( 2005 ) ; and weatherley et al . ( 2005 ) . in total , we have plotted 71 detections and 30 upper limits in fig . we note , however , that many of the emission line detections are for candidates that have not yet been confirmed with spectroscopy or multiple narrow - band imaging . for the few objects where multiple emission lines have been detected , we have plotted the values from h-@xmath0 , h-@xmath79 , or [ o ii ] , in that order of preference . all the shown candidate detections and 3 @xmath2 upper limits have been normalized to @xmath76 , @xmath77 , and @xmath78 km s@xmath5 mpc@xmath5 . once again , the prescription of kennicutt ( 1998 ) has been used for the conversion from the h-@xmath0 luminosity @xmath49 to the sfr , and a ratio @xmath51 for case - b recombination has been assumed . no correction has been made for dust attenuation , but we examine this issue in more detail below . our apo fp constraints are among the lowest , but are clearly consistent with many other measurements . the open inverted triangles at @xmath81 are based on spectroscopic ( slit ) observations of h-@xmath0 . the unfilled circles are candidate objects with h-@xmath0 emission detected at the absorber redshift , but are often more than @xmath82 away from the quasar , and have a lower precision in redshift . the curves in fig . 8 are useful for comparing the data with global predictions based on the luminosity density of galaxies from the deep galaxy imaging surveys . since most of the data in fig . 8 are for objects in dla fields , we show the calculations of bunker et al . ( 1999 ) for the predicted cross - section - weighted sfr in dlas . these models use two alternative sets of assumptions about the number of absorbers per unit redshift and the distribution of global sfr among individual absorbers at a given redshift . the thick and thin solid curves show the ld5 and ld0 `` large disk '' calculations ( for @xmath83 and @xmath84 respectively ) , of bunker et al . based on the closed - box pei & fall ( 1995 ) models . the ld models assume that dlas are the progenitors of spiral galaxies , with space density equal to that of local spirals , but with size and sfr of each dla larger in the past compared to that of a local spiral . the dashed curve shows the h5 and h0 predictions of bunker et al . ( 1999 ) ( for @xmath83 and @xmath84 respectively ) for the `` hierarchical '' hypothesis , which assumes that there were multiple dlas at high redshift corresponding to every present - day spiral ( i.e. that dlas were sub - galactic fragments that later merged to form present - day spirals ) . thus in the h5 and h0 models , dlas have the same distribution of gas cross - section sizes as in local spirals , but with a higher space density in the past , and have smaller sfrs than in the corresponding `` large - disk '' models . the ld curve , if computed for @xmath76 , @xmath77 , and @xmath78 km s@xmath5 mpc@xmath5 , would lie between the ld5 and ld0 curves , since the distance and time scales for the former cosmology are intermediate between those for @xmath85 and @xmath86 . this can also be seen by comparing the comoving global sfr predicted by the pei & fall ( 1995 ) closed - box models for @xmath83 and @xmath84 , with that predicted by the @xmath87-cold dark matter ( @xmath87-cdm ) hydrodynamical simulations of nagamine , cen , & ostriker ( 2000 ) . thus , a large fraction of the observed sfrs would appear to fall significantly below the prediction of the large - disk scenario . the h curve for this @xmath87-cdm cosmology would be identical to the h5 and h0 curves ( since the latter curves coincide with each other ) . a large fraction of the data points in fig . 8 thus appear to be more consistent with the hierarchical scenario , suggesting perhaps that many absorbers or their companion galaxies may be arising in star - forming dwarf galaxies or sub - galactic fragments that merged later to form present - day galaxies . however , several detections and upper limits , including our fp limits , appear to be considerably below even the hierarchical prediction . indeed , about 63@xmath88 of the detections and about 73@xmath88 of the limits plotted in fig . 8 are less than 5 @xmath8 yr@xmath5 . such large local deviations for the absorber fields from the global mean would be surprising . taken at face value , fig . 8 suggests that the absorption - based view of the cosmic star formation history could be quite different from the emission - based view , i.e. , from the star formation history inferred on the basis of the direct galaxy imaging surveys such as the hubble deep field . low sfrs for galaxies in absorber fields would also be consistent with the low global metallicities found in dlas ( e.g. , kulkarni et al . 2005 and references therein ) . similar suggestions have also been made by wolfe et al . ( 2003 ) , who inferred relatively high sfr values for some dlas based on c ii * absorption , but found the high sfrs to be inconsistent with the low metallicities observed in the dlas . we note , however , that while the c ii * method may potentially offer an interesting way to estimate sfrs in dlas , it seems less direct and more model - dependent than the emission - line based constraints . there are also other possible interpretations of fig 8 . it is possible that the true sfrs in galaxies in the absorber fields are higher , but their emission lines , especially ly-@xmath0 , are attenuated by dust . it is well known that resonance scattering of ly-@xmath0 , in the presence of dust , can lead to quenching of the lyman-@xmath0 emission in high-@xmath89 systems ( e.g. , charlot & fall 1991 ) . presence of dust in some ly-@xmath0 emitting regions is also suggested from the recent detection of 24 @xmath18 m emission in spitzer space telescope images of laes at @xmath72 in an absorber field ( colbert et al . on the other hand , there are several reasons to expect that ly-@xmath0 emission may still be seen from absorbers and their companion galaxies , in at least some cases . first , the very knowledge of a dla means that the quasar in which it appears is not greatly affected by dust attenuation . ly-@xmath0 is easily seen from regions of such low extinction . second , the dust - to - gas ratios in dlas inferred from relative abundances such as [ cr / zn ] or [ fe / zn ] are much smaller than in the milky way ( e.g. , pettini et al . 1997 ; khare et al . 2004 ; and references therein ) . in a recent study of a large number of sdss quasar spectra , we have recently found evidence for a statistically significant but small amount of dust in quasar absorbers ( york et al . finally , there are several examples of high-@xmath9 ly-@xmath0 emitters with very little dust attenuation ( e.g. , giavalisco et al . 1994 ; francis et al . 1996 ; hu , cowie , & mcmahon 1998 ; kudritzki et al . 2000 ) . the effect of dust attenuation is expected to be much less severe in the h-@xmath0 line . indeed , the sfr constraints based on h-@xmath0 detections in most high-@xmath9 dla candidates or companions shown in fig 8 are considerably higher than the constraints from the ly-@xmath0 emission searches . considering detections alone , the median sfrs from h-@xmath0 , ly-@xmath0 , and [ oii ] are 35.9 , 3.2 , and 0.3 @xmath8 yr@xmath5 , respectively . if both detections and limits are considered , the median sfrs from h-@xmath0 , ly-@xmath0 , and [ oii ] are 28.2 , 2.4 , and 0.3 @xmath8 yr@xmath5 treating the limits as detections , and 18.8 , 0.1 , and 0.3 @xmath8 yr@xmath5 treating the limits as zeros . it is tempting to think that the difference between the median h-@xmath0 and ly-@xmath0 values could be partly caused by dust extinction . however , it is not clear whether this is a significant effect , since ly-@xmath0 measurements ( candidates or limits ) are not available for most of the h-@xmath0 candidates . in the few objects that show detections of multiple emission lines , the sfr estimates from the available lines are usually consistent within a factor of @xmath90 . also , some of the h-@xmath0 candidates are at large angular separations from the quasars and have less accurate redshifts . thus , there is no clear indication that ly-@xmath0 in the h-@xmath0 candidates is attenuated by dust . in any case , dust alone may not explain low ly-@xmath0 emission in every individual case , because the extent of ly-@xmath0 attenuation also depends on several other factors , such as the orientation , the topology of the h ii region , and the distribution of stars , gas and dust within the absorber . finally , dust attenuation can not explain why nearly all of the sfrs inferred from [ o ii ] and @xmath91 of the sfrs inferred from h-@xmath0 are low . another possibility is that the star - forming regions in the absorber galaxies are compact , lie directly in front of the quasars , and hence get lost in the quasar point spread function ( psf ) in our study and other ground - based studies so far . for example , if the absorbing galaxies had star - forming cores comparable in size to those in the lyman - break galaxies [ typically @xmath92 kpc ] aligned perfectly in front of the quasars , it would not be possible to resolve them with studies such as our own ( and most other ground - based studies used in fig . in other words , the sfr constraints derived from such studies may be more appropriate for the companion galaxies of the absorbers , rather than the absorbers themselves . it is difficult to rule out this possibility without high - resolution imaging data . however , the chance of having the star forming region exactly in front of the quasar in _ each _ case is small . indeed , the absence of emission within the ly-@xmath0 absorption profiles in the published spectra for most dlas ( including those from our study ) suggests that they do not have star - forming regions perfectly aligned with the background quasars . even if the absorber galaxies themselves were small , they are unlikely to be isolated objects , since such small galaxies are expected to occur as companions to larger galaxies within a few hundred kpc . in any case , it would still be surprising why the few existing high - resolution imaging studies of absorber galaxies have often failed to detect h-@xmath0 emission or found relatively weak ly-@xmath0 emission ( e.g. , bouche et al . 2001 ; kulkarni et al . 2000 , 2001 ; mller et al . 2002 ) . future narrow - band imaging studies of more high - redshift quasar absorber fields would help to understand whether the low ly-@xmath0 fluxes we find are representative of the absorber galaxies . furthermore , more narrow - band imaging or spectroscopic studies in the near - infrared will give access to the h-@xmath0 emission line from the @xmath93 absorbers . a systematic comparison of the h-@xmath0 and ly-@xmath0 data for the same absorbers can help to understand whether the emission lines in the galaxies in absorber fields are simply attenuated by dust , or whether these galaxies truly have low sfrs . it will thus be interesting to look at ly-@xmath0 emission from the objects reported to show strong h-@xmath0 emission , and to look at h-@xmath0 near the quasars for which we have limits on ly-@xmath0 . finally , more high - resolution narrow - band imaging and/or spectroscopic studies would be especially important to understand whether the star formation in the absorber galaxies is restricted to compact regions . this paper is based on observations obtained with the apache point observatory 3.5-meter telescope , which is owned and operated by the astrophysical research consortium . we thank jonathan brinkmann for assistance with the fabry - perot setup and calibration at the apo . we also thank andrew bunker for helpful discussion and betty stobie for providing and assisting with the idp-3 package . finally , we are grateful to an anonymous referee whose comments helped to improve this paper . vpk , dgt , and jm acknowledge support from the national science foundation grant ast-0206197 and from the university of south carolina research foundation . bechtold , j. , elston , r. , yee , h. k. c. , ellingson , e. , & cutri , r. m. 1998 , in ` the young universe : galaxy formation and evolution at intermediate and high redshift ' , ed . s. dodorico , a. fontana , and e. giallongo , asp conf . series , ( pasp ) , 146 , 241 _ * fig . 1 * apo images of the field of q0216 + 080 . ( a ) @xmath95 b - band image ( top left ) ; ( b ) @xmath95 narrow - band image before continuum subtraction ( top right ) ; ( c ) @xmath95 narrow - band image after continuum subtraction ( bottom left ) ; and ( d ) @xmath39 narrow - band image after continuum subtraction ( bottom right ) . see attached gif images . _ _ measurements of star formation rates ( in @xmath8 yr@xmath5 ) for candidate objects in quasar absorber fields , from narrow - band imaging and spectroscopic searches for ly-@xmath0 , h-@xmath0 , h-@xmath79 , [ o ii ] and [ o iii ] emission lines . data points are from our apo ly-@xmath0 survey ( this work ) , our previous nicmos h-@xmath0 imaging ( kulkarni et al . 2000 , 2001 ) , and other literature ( see text ) . most of the higher values are based on candidate h-@xmath0 emitters , often located far from the quasar lines of sight . the thick solid ( upper ) and thin solid ( middle ) curves show , respectively , the calculations of bunker et al . ( 1999 ) for the predicted cross - section - weighted sfr in the large - disk scenario for @xmath83 and @xmath84 . the dashed curve shows the calculations of bunker et al . ( 1999 ) for the hierarchical scenario for @xmath83 and @xmath84 . all of these curves are based on the closed - box global sfr models of pei & fall ( 1995 ) . _ llllllr qso & r.a.(j2000 ) & dec.(j2000 ) & @xmath96 & @xmath97 & known ions & @xmath98 + & & & & & & ( ) + q0216 + 080&02:18:57.3 & + 08:17:28.0&2.9957&2.2931&civ , aliii , alii,& ... @xmath99 + & & & & & siii , feii ; dla + q0636 + 680&06:42:04.3 & + 67:58:35.6 & 3.1775&2.3112&civ , cii , alii & ... + q0956 + 123&09:58:52.3 & + 12:02:43.2 & 3.306&2.3104&civ , siiv , alii&1.42 + q1209 + 093&12:11:34.9 & + 09:02:22.8 & 3.297&2.5822&civ , alii , feii;&21.2 + & & & & & dla + q1442 + 101&14:45:16.5 & + 09:58:36.2 & 3.535&2.5632&ovi , civ , siiv , & 1.40 + & & & & & ciii , siiii , siii , oi + q2233 + 131&22:36:19.2&+13:26:20.0&3.2978&2.5537&civ , cii , siiv , siiii,&5.35 + & & & & & siii , oi ; sub - dla + 53w002&17:14:14.7&+50:15:29.7 & ... & ... & ... & ... + ( calibration & ... & ... & ... & ... & ... & ... + field ) & ... & ... & ... & ... & ... & ... + q0216 + 080 & 2001/11/10&05:55:28.87&1.111&blue&4050/160&4002.2&2400&14.69 + ... & 2001/11/10&06:36:18.15&1.111&blue&4050/160&4002.2&1200 & + ... & 2001/11/11&05:42:48.66&1.102&blue&4050/160&4002.2&2400 & + ... & 2001/11/11&06:52:30.75&1.125&blue&4050/160&4002.2&1660 & + ... & 2001/11/12&05:20:37.43&1.111&blue&4050/160&4001.3&2400 & + ... & 2001/11/12&06:05:54.94&1.100&blue&4050/160&4001.3&2400 & + ... & 2001/12/15&03:17:36.77&1.107&blue&4050/160&4002.2&2400 & + ... & 2001/12/15&04:00:38.97&1.101&blue&4050/160&4002.2&2400 & + ... & 2001/12/15&04:50:23.34&1.139&blue&4050/160&4002.2&2400 & + ... & 2001/12/15&05:32:31.49&1.216&blue&4050/160&4002.2&2400 & + ... & 2002/11/03&06:59:28.92 & 1.106 & vis - b & 4050/160&4008.0 & 2400 & + ... & 2002/11/03&07:52:40.87&1.163&vis - b&4050/160&4008.0 & 2400 & + ... & 2002/11/08&07:42:27.53&1.180&vis - b&4050/160&4008.0 & 1800 & + & & & & & & & + ... & 2000/10/26&05:23:00.92&1.201& ... &b&4400&480 & + ... & 2000/10/26&05:32:58.88&1.180& ... &b&4400&480 & + ... & 2000/10/26&05:42:02.58&1.164& ... &b&4400&480 & + ... & 2000/10/26&05:51:06.28&1.150& ... &b&4400&480 & + ... & 2000/10/26&06:00:28.58&1.137& ... &b&4400&480 & + ... & 2001/12/15&01:21:29.11&1.338& ... &b&4400&300 & + ... & 2001/12/15&01:27:45.25&1.314& ... &b&4400&300 & + ... & 2001/12/15&01:34:03.80&1.292& ... &b&4400&300 & + ... & 2001/12/15&01:40:22.75&1.272& ... &b&4400&300 & + ... & 2001/12/15&01:46:35.10&1.254& ... &b&4400&300 & + & & & & & & & + & & & & & & & + q0636 + 680 & 2000/10/26&10:51:55.81&1.229&blue&4050/160&4024&2400&14.66 + ... & 2000/10/26&11:33:12.48&1.224&blue&4050/160&4024&2400 & + ... & 2001/02/22&03:20:22.82&1.225&blue&4050/160&4024.3&2400 & + ... & 2001/02/22&04:18:32.24&1.232&blue&4050/160&4024.3&2400 & + ... & 2001/02/22&05:06:11.28&1.260&blue&4050/160&4024.3&2400 & + ... & 2001/12/15&07:15:20.01&1.236&blue&4050/160&4024.2&2400 & + ... & 2001/12/15&07:56:38.23&1.224&blue&4050/160&4024.2&2400 & + ... & 2001/12/15&08:39:13.21&1.228&blue&4050/160&4024.2&2400 & + ... & 2001/12/15&09:27:39.32&1.252&blue&4050/160&4024.2&2400 & + ... & 2002/03/12&02:56:26.66&1.228&blue&4050/160&4024.2&2400 & + ... & 2002/03/12&03:38:47.01&1.247&blue&4050/160&4024.2&2400 & + ... & 2002/11/03&10:45:35.05&1.224&vis - b&4050/160&4030.0&2400 & + ... & 2002/11/03&11:29:28.69&1.229&vis - b&4050/160&4030.0&2400 & + ... & 2002/11/05&09:44:12.32&1.242&vis - b&4050/160&4030.0&2400 & + & & & & & & & + ... & 2000/10/26&10:07:53.96&1.251& ... &b&4400&480 & + ... & 2000/10/26&10:17:24.49&1.244& ... &b&4400&480 & + ... & 2000/10/26&10:26:39.20&1.239& ... &b&4400&480 & + ... & 2000/10/26&10:35:43.11&1.235& ... &b&4400&480 & + ... & 2001/02/25&05:16:15.67&1.281& ... &b&4400&300 & + ... & 2001/02/25&05:22:41.63&1.288& ... &b&4400&300 & + ... & 2001/02/25&05:29:27.60&1.296& ... &b&4400&300 & + & & & & & & & + & & & & & & & + q0956 + 123&2001/02/22&06:23:39.98&1.077 & blue&4050/160 & 4023.3&2400&14.79 + ... & 2001/02/22&07:24:08.73&1.078&blue&4050/160 & 4023.3&2400 & + ... & 2001/02/22&08:16:52.25&1.135&blue&4050/160 & 4023.3&2400 & + ... & 2001/02/22&09:24:17.19&1.312&blue&4050/160 & 4023.3&2400 & + ... & 2001/02/25&08:38:17.40&1.204&blue&4050/160&4023.4&2400 & + ... & 2001/05/22&03:18:47.08&1.258&blue&4050/160&4023.3&2400 & + ... & 2002/03/12&05:13:05.87&1.078&blue&4050/160&4023.2&2400 & + ... & 2002/03/12&05:55:28.03&1.071&blue&4050/160&4023.2&2400 & + ... & 2002/03/12&06:44:56.70&1.104&blue&4050/160&4023.2&2400 & + & & & & & & & + ... & 2001/02/25&06:10:45.09&1.078& ... &b&4400&300 & + ... & 2001/02/25&06:17:40.16&1.074& ... &b&4400&300 & + ... & 2001/02/25&06:24:01.83&1.072& ... &b&4400&300 & + ... & 2001/02/25&06:30:58.02&1.070& ... &b&4400&300 & + ... & 2001/02/25&06:37:32.38&1.069& ... &b&4400&300 & + ... & 2001/02/25&06:49:41.66&1.069& ... &b&4400&300 & + ... & 2001/02/25&07:06:17.69&1.074& ... &b&4400&300 & + ... & 2001/02/25&07:12:54.06&1.078& ... &b&4400&300 & + & & & & & & & + & & & & & & & + q1209 + 093 & 2001/05/20&04:42:28.87&1.154&blue&4300/135&4353.6&2400&7.01 + ... & 2001/05/20&05:28:37.23&1.260&blue & 4300/135 & 4353.6&2400 & + ... & 2001/05/22&05:11:26.45&1.233&blue & 4300/135&4353.5&2400 & + ... & 2001/05/23&03:41:53.18&1.101&blue & 4300/135&4353.7&2400 & + ... & 2001/05/23&04:24:29.14&1.145&blue & 4300/135&4353.6&2400 & + ... & 2002/03/11&08:52:16.27&1.119&blue & 4300/135&4353.5&2400 & + ... & 2002/03/12&08:25:38.11&1.101&blue&4300/135&4353.5&2400 & + ... & 2002/03/12&09:17:40.82&1.159&blue&4300/135&4353.5&2400 & + & & & & & & & + ... & 2001/05/23&05:22:34.56&1.277& ... &b&4400&300 & + ... & 2001/05/23&05:37:57.81&1.332& ... &b&4400&300 & + ... & 2001/05/23&05:44:12.36&1.357& ... &b&4400&300 & + ... & 2001/05/23&05:50:36.43&1.384& ... &b&4400&300 & + ... & 2001/05/23&05:56:55.87&1.413& ... &b&4400&300 & + ... & 2001/05/23&06:03:07.01&1.444& ... &b&4400&300 & + ... & 2001/05/23&06:09:17.35&1.477& ... &b&4400&300 & + ... & 2001/05/23&06:15:38.11&1.514& ... &b&4400&300 & + & & & & & & & + q1442 + 101&2001/05/20&07:29:32.74&1.170&blue&4300/135&4330.5&2400&6.10 + ... & 2001/05/20&08:17:28.39&1.299&blue&4300/135&4330.4&2400 & + ... & 2001/05/21&06:37:53.56&1.104&blue&4300/135&4330.6&2400 & + ... & 2001/05/21&07:27:17.70&1.174&blue&4300/135&4330.5&2400 & + ... & 2001/05/21&08:09:09.42&1.284&blue&4300/135&4330.4&2400 & + ... & 2001/05/22&06:15:29.60&1.091&blue&4300/135&4330.5&2400 & + ... & 2001/05/22&06:57:37.14&1.130&blue&4300/135&4330.5&2400 & + ... & 2001/05/23&06:51:26.89&1.127&blue&4300/135&4330.5&2400 & + ... & 2001/05/23&07:33:07.00&1.204&blue&4300/135&4330.5&2400 & + & & & & & & & + ... & 2001/02/25&10:03:28.53&1.153& ... &b&4400&300 & + ... & 2001/02/25&10:10:44.33&1.141& ... &b&4400 & 300 & + ... & 2001/02/25&10:18:19.75&1.130& ... &b&4400&300 & + ... & 2001/02/25&10:26:38.82&1.120& ... &b&4400&300 & + ... & 2001/02/25&11:21:21.65&1.085& ... &b&4400&300 & + ... & 2001/02/25&11:32:29.47&1.085& ... &b&4400&300 & + ... & 2001/02/25&11:41:09.15&1.087& ... &b&4400&300 & + ... & 2001/02/25&11:48:41.57&1.089& ... &b&4400&300 & + ... & 2001/02/25&11:55:50.50&1.0938& ... &b&4400&300 & + ... & 2001/05/23&08:21:14.63&1.359& ... &b&4400&300 & + ... & 2001/05/23&08:27:35.43&1.387& ... &b&4400&300 & + ... & 2001/05/23&08:33:59.98&1.418& ... &b&4400&300 & + & & & & & & & + & & & & & & & + q2233 + 131&2000/10/26&03:45:44.77&1.066&blue&4300/135&4319&2400&5.59 + ... & 2000/10/27&01:38:14.59&1.150&blue&4300/135&4314.3&2400 & + ... & 2000/10/27&02:41:43.61&1.070&blue&4300/135&4317.0&2400 & + ... & 2000/10/27&03:32:30.68&1.062&blue&4300/135&4318&2400 & + ... & 2000/10/27&04:20:34.25&1.097&blue&4300/135&4318&2400 & + ... & 2000/10/27&05:12:21.30&1.190&blue&4300/135&4318.5&2400 & + ... & 2000/10/27&06:11:24.96&1.398&blue&4300/135&4319&2400 & + ... & 2001/11/10&02:29:02.38&1.060&blue&4313/116&4318.9&2400 & + ... & 2001/11/10&03:10:40.90&1.081&blue&4313/116&4318.9&2400 & + ... & 2001/11/10&03:52:49.45&1.136&blue&4313/116&4318.9&2400 & + ... & 2001/11/10&04:34:24.56&1.233&blue&4313/116&4318.9&2400 & + ... & 2001/11/11&02:01:10.21&1.062&blue&4313/116&4318.9&2400 & + ... & 2001/11/11&02:45:46.09&1.066&blue&4313/116&4318.9&2400 & + ... & 2001/11/12&02:18:11.07&1.060&blue&4313/116&4318.9&2400 & + ... & 2001/11/12&03:01:43.69&1.080&blue&4313/116&4318.9&2400 & + ... & 2002/11/04&03:08:18.76 & 1.064&vis - b&4300/135&4325.0&1740 & + ... & 2002/11/06&01:29:15.00&1.104&vis - b&4300/135&4325.0&2400 & + ... & 2002/11/06&02:31:17.24&1.060&vis - b&4300/135&4325.0&800 & + ... & 2002/11/06&05:02:00.19&1.268&vis - b&4300/135&4325.0&2400 & + & & & & & & & + ... & 2000/10/26&02:42:34.68&1.072& ... &b&4400&480 & + ... & 2000/10/26&02:53:33.87&1.066& ... &b&4400&480 & + ... & 2000/10/26&03:06:41.39&1.061& ... &b&4400&480 & + ... & 2000/10/26&03:17:01.37&1.060& ... &b&4400&480 & + ... & 2000/10/26&03:28:07.59&1.060& ... &b&4400&480 & + ... & 2001/11/11&03:54:43.13&1.147& ... &b&4400&2400 & + ... & 2000/10/25&05:26:24.96&1.205& ... &b&4400&1200 & + & & & & & & & + & & & & & & & + 53w002&2001/05/20&09:45:49.27&1.086&blue&4155/160&4128.4&2400&8.31 + ... & 2001/05/21&09:34:32.16&1.079&blue&4155/160&4128.5&2400 & + ... & 2001/05/21&10:15:54.17&1.126&blue&4155/160&4128.6&2400 & + ... & 2001/05/22&09:08:42.61&1.063&blue&4155/160&4128.3&2400 & + ... & 2001/05/23&09:31:39.77&1.084&blue&4155/160&4128.3&2400 & + & & & & & & & + ... & 2001/05/22&09:57:53.15&1.108 & ... & b&4400&300 & + ... & 2001/05/22&10:04:47.73&1.117 & ... & b&4400&300 & + ... & 2001/05/22&10:10:54.66&1.125 & ... & b&4400&300 & + ... & 2001/05/22&10:17:17.82&1.134 & ... & b&4400&300 & + ... & 2001/05/22&10:23:55.19&1.145 & ... & b&4400&300 & + ... & 2001/05/22&10:34:30.57&1.163 & ... & b&4400&300 & + ... & 2001/05/22&10:41:24.96&1.176 & ... & b&4400&300 & + ... & 2001/05/22&10:52:14.56&1.197 & ... & b&4400&300 & + ... & 2001/05/23&08:44:33.56&1.054 & ... & b&4400&300 & + ... & 2001/05/23&08:51:20.34&1.057 & ... & b&4400&300 & + ... & 2001/05/23&08:57:47.50&1.060 & ... & b&4400&300 & + ... & 2001/05/23&09:05:17.92&1.064 & ... & b&4400&300 & + & & & & & & & + llcc qso & @xmath97 & @xmath102(erg s@xmath5 @xmath6 ) ) & sfr ( @xmath8 yr@xmath5)@xmath103 + q0216 + 080&2.2931&@xmath104&@xmath105 + q0636 + 680&2.3112&@xmath106&@xmath107 + q0956 + 123&2.3104&@xmath108&@xmath105 + q1209 + 093&2.5822&@xmath109&@xmath110 + q1442 + 101&2.5632&@xmath111&@xmath112 + q2233 + 131&2.5537&@xmath113&@xmath114 + @xmath100 : 3 @xmath2 upper limits on lyman-@xmath0 flux for a 2 pixel x 2 pixel region , corresponding to a physical size of @xmath115 kpc x 6.0 kpc at @xmath116 ; @xmath117 : 3 @xmath2 upper limits on sfr .

we have carried out a deep narrow - band imaging survey of six fields with heavy - element quasar absorption lines , using the goddard fabry - perot ( fp ) system at the apache point observatory ( apo ) 3.5-meter telescope . the aim of these observations was to search for redshifted ly-@xmath0 emission from the galaxies underlying the absorbers at @xmath1 and their companion galaxies . the 3 @xmath2 sensitivity levels ranged between @xmath3 and @xmath4 erg s@xmath5 @xmath6 in observed - frame ly-@xmath0 flux . no significant ly-@xmath0 emitters were detected at @xmath7 level . the absence of significant ly-@xmath0 emission implies limits on the star formation rate ( sfr ) of 0.9 - 2.7 @xmath8 yr@xmath5 per 2-pixel x 2-pixel region , if no dust attenuation is assumed . we compare our results with those from other emission - line studies of absorber fields and with predictions for global average sfr based on the models of cosmic chemical evolution . our limits are among the tightest existing constraints on ly-@xmath0 emission from galaxies in absorber fields , but are consistent with many other studies . in the absence of dust attenuation , these studies suggest that sfrs in a large fraction of objects in the absorber fields may lie below the global mean sfr . however , it is possible that dust attenuation is responsible for the low emission line fluxes in some objects . it is also possible that the star - forming regions are compact and at smaller angular separations from the quasar than the width of our point spread function and , get lost in the quasar emission . we outline future observations that could help to distinguish between the various possibilities .

the recent experimental progress in manipulating and controlling trapped neutral atoms in optical lattices by quantum optical means @xcite allows for a number of novel applications in a variety of different fields like quantum information processing @xcite , atom interferometry @xcite , and atomic and molecular physics @xcite . one of the most important features in all of these applications is the large degree of control by quantum optical techniques over the structure and the parameters of the hamiltonian describing the atomic system . this control allows to realize and deploy a number of lattice hamiltonians @xcite which are frequently used as toy models for strongly correlated condensed matter systems and therefore theoretically very well studied . however , many of the most interesting effects in strongly correlated 2d systems appear if an external magnetic field is applied @xcite . apart from rotating an atomic cloud @xcite , as assumed for example in the study of laughlin states with bosonic atoms in ref . @xcite , there seems to be at present no obvious way of implementing lattice hamiltonians resembling the effects of magnetic fields with neutral atoms . in this paper we propose a 2d setup for neutral atoms which allows to engineer terms in single - band hubbard hamiltonians corresponding to an external magnetic field . an optical lattice provides the discrete periodic spatial structure and we will use lasers instead of a magnetic field to induce a phase for particles hopping around a closed path in the lattice resembling an effective magnetic field . we will show that the strength of this effective magnetic field can be varied by laser parameters and be made arbitrarily large , a situation first theoretically investigated by hofstadter @xcite for electrons . the studies by hofstadter predicted the emergence of fractal energy bands @xmath0 that resemble the shape of a butterfly when plotted against the parameter @xmath1 , where @xmath2 is the area of one of the elementary cells of the lattice , @xmath3 is the strength of the magnetic field , and @xmath4 is the charge of the particles ( cf . fig [ fig1 ] ) . the phase @xmath5 is gained by the wave function of a particle due to the magnetic field when it hops around a plaquette of the lattice . as shown by hofstadter the nature of the energy bands depends crucially on the parameter @xmath6 . if @xmath7 with @xmath8 integers , i.e. @xmath6 is a rational number , the energy spectrum splits into a finite number of exactly @xmath9 bands whereas if @xmath6 is irrational the energy spectrum breaks up in infinitely many bands and thus the fractal structure shown in fig . [ fig1 ] emerges ( for a detailed discussion on the properties of the hofstadter butterfly see @xcite ) . are shown as black dots for different @xmath6 , and @xmath10 is the hopping energy as defined in the text . the most dominant feature is the splitting of the energy band into @xmath9 subbands for @xmath11 . for further details of this plot see @xcite . [ fig1 ] ] fractal energy band structures are believed to play an important role for a number of effects like the quantum hall effect induced by magnetic fields in strongly correlated electron systems @xcite . therefore it is desirable to study the hofstadter butterfly experimentally under well defined conditions . however , it turns out that the area of the elementary cells in metals where fractal energy bands could possibly be seen is so small that huge magnetic fields would be required to obtain values of @xmath6 which are on the order of @xmath12 @xcite . also in more sophisticated superlattice setups with larger area @xmath2 it is experimentally very difficult to obtain direct clear experimental evidence of the hofstadter butterfly @xcite . we will consider a 2d system of ultracold atoms trapped in one layer in the @xmath13 plane of a three dimensional optical lattice . the atoms are in the lowest motional band which can be achieved e.g. by loading the optical lattice from a bose - einstein condensate @xcite . hopping along the @xmath14 direction is turned off completely by the lattice potential . different columns of the lattice trap atoms in internal states @xmath15 ( @xmath16 ) ( denoted in fig . [ fig2]a by open ( closed ) circles ) @xcite . in addition the optical lattice is either accelerated along the @xmath17-axis or an inhomogeneous static electric field is applied and two raman lasers driving transitions between the states @xmath15 and @xmath16 induce hopping along the @xmath17-axis while hopping along the @xmath18-axis is controlled by the depth of the optical lattice along this direction . this setup corresponds to applying a magnetic field with a parameter @xmath19 where @xmath20 is the wave number of the raman lasers along the @xmath18 direction and @xmath21 the wave length of the lasers creating the optical lattice . we also note that the atomic setup we are going to describe here can be used for a large number of other purposes . it is straightforward to add terms to the system that correspond to an external electric field . also the atoms will interact with each other via collisional contact interactions @xcite and off site interactions can be engineered by dipolar rydberg interactions @xcite . therefore the setup presented here can be used for a number of studies related to the behavior of charged particles in a 2d configuration subject to magnetic and electric fields and also to study strongly interacting and thus strongly correlated systems . furthermore it might be possible to extend this model to different geometries of optical lattices . in this work we will concentrate on a possible setup required to implement the effective magnetic field in an optical lattice . we will discuss in detail the laser setup which leads to an effective magnetic flux through the optical lattice , and calculate the corresponding matrix elements in sec . [ model ] . we also show that it is possible to reach each point within the hofstadter butterfly apart from a negligibly small region around @xmath22 with the proposed setup . in sec . [ meas ] we suggest one possibility of measuring some of the basic properties of the hofstadter butterfly and discuss the limitations on the resolution for measuring the energy bands . we also give a brief account of the interaction effects . finally we conclude with a short outlook on how the present setup could be extended in sec . [ conclusion ] . while the focus of the present work is the derivation of the single - particle terms in the hubbard hamiltonian mimicking a strong magnetic field , we see as one of the main motivations the extension of strongly correlated many - atom systems in strong ( effective ) magnetic fields . in this section we discuss the experimental setup required to produce a hofstadter butterfly for neutral atoms . we first present the optical lattice setup , then introduce an additional acceleration or static electric field and finally describe in detail the additional lasers required for our purpose . we consider a three dimensional optical lattice created by standing wave laser fields which generate a potential for the atomic motion of the form ( we use @xmath23 throughout the paper ) @xmath24 with @xmath25 the wave - vector of the light and spatial coordinate @xmath26 . the recoil energy is given by @xmath27 with @xmath28 the mass of the atoms . we assume the lattice to trap atoms in two different internal hyperfine states @xmath16 and @xmath15 and the depth of the lattice in @xmath17- and @xmath14-direction to be so large that hopping in these directions due to kinetic energy is prohibited @xcite . furthermore we assume that adjusting the polarization of the lasers which confine the particles in the @xmath17-direction allows to place the potential wells trapping atoms in the different internal states at distances @xmath29 with respect to each other @xcite as shown in fig . therefore the resulting 2d lattice has a lattice constant ( disregarding the internal state ) in @xmath17-direction of @xmath30 and in @xmath18-direction of @xmath31 . we restrict our analysis to one layer of the optical lattice in the @xmath13 plane since in the following there will neither be hopping nor interactions between different layers . the dynamics of bosonic atoms occupying the lowest bloch band of this optical lattice is well described by the bose - hubbard model ( bhm ) @xcite @xmath32 where @xmath33 is the hopping matrix element for particles to tunnel between adjacent sites along the @xmath18-direction . the energy difference between the two hyperfine states is @xmath34 and the operators @xmath35 ( @xmath36 ) are bosonic destruction ( creation ) operators for atoms in the lowest motional band located at the site which is centered at @xmath37 , where @xmath38 and @xmath39 . the corresponding mode functions are the localized wannier functions @xmath40 @xcite found by suitable superpositions of the bloch functions for the lowest bloch band of the lattice . since in @xmath17-direction the separation between two neighboring atoms is half the original lattice constant @xmath41 the overlap of the mode functions of particles in adjacent lattice sites might lead to significant nearest neighbor interactions described by @xmath42 whereas we neglect any other offsite interactions @xcite . the parameter @xmath43 describes the onsite interaction between two particles occupying the same site . this onsite interaction may depend on the column index @xmath44 because of different internal states with different scattering lengths occupying different columns . since for even [ odd ] @xmath44 the operator @xmath35 describes atoms in internal states @xmath16 , [ @xmath15 ] and the wannier functions for sites which are separated by multiples of the original lattice constant @xmath41 are orthogonal to each other we find the commutation relations @xmath46 = \delta_{n , n ' } \delta_{m , m'}$ ] with @xmath47 the kronecker delta . the details of the derivation of the above hamiltonian can be found in @xcite where also the definitions for the parameters @xmath48 , @xmath42 , and @xmath33 are given . ( @xmath16 ) . a ) hopping in the @xmath18-direction is due to kinetic energy and described by the hopping matrix element @xmath33 being the same for particles in states @xmath16 and @xmath15 . along the @xmath17-direction hopping amplitudes are due to the additional lasers . b ) trapping potential in @xmath17-direction . adjacent sites are set off by an energy @xmath49 because of the acceleration or a static inhomogeneous electric field . the laser @xmath50 is resonant for transitions @xmath51 due to the offset of the lattice sites . because of the spatial dependence of @xmath52 atoms hopping around one plaquette get phase shifts of @xmath53 where @xmath54 as indicated in a).[fig2 ] ] in addition to the above setup we assume an energy offset of @xmath49 between two adjacent sites in @xmath17-direction as shown in fig . this can be done by accelerating the optical lattice along the @xmath17-axis with a constant acceleration @xmath55 leading to an additional potential energy term for one atom of @xmath56 . alternatively , if both of the internal atomic states @xmath16 and @xmath15 have the same static polarizability @xmath57 an inhomogeneous static electric field of the form @xmath58 can be applied to the optical lattice yielding a potential energy term @xmath59 . we keep this additional potential energy small compared to the optical lattice potential and treat @xmath60 as a perturbation . in second quantization this yields @xmath61 where @xmath62 in the case of an inhomogeneous electric field and @xmath63 if the lattice is accelerated . the condition for this perturbative treatment to be valid is @xmath64 with @xmath65 the trapping frequency of the optical lattice in the @xmath17-direction . finally , we want to induce hopping along the @xmath17-direction by two additional lasers driving raman transitions between the states @xmath15 and @xmath16 . each of them consists of two running plane waves chosen to give space dependent rabi frequencies of the form @xmath66 with @xmath67 the magnitude of the rabi frequencies , and detunings @xmath68 . we choose the parameters @xmath69 , @xmath70 , and @xmath71 . as discussed in detail in appendix [ app1 ] this can always be achieved by superimposing two running wave laser beams incident in the @xmath13-plane for @xmath72 with @xmath73 the speed of light . we assume the lasers not to excite any higher lying motional bloch bands and also no transitions with detunings of the order of @xmath49 , i.e. , @xmath74 . then the lasers @xmath75 will only drive transitions @xmath76 if @xmath44 is even ( odd ) and we can neglect any influence of the nonresonant transitions . we find the following hamiltonian describing the effect of the additional lasers @xmath77 where we have neglected all other terms due to being nonresonant and defined matrix elements @xmath78 for even @xmath44 @xmath79 and for odd @xmath44 @xmath80 for an optical lattice potential of the form eq . ( [ v ] ) the wannier functions can be written as a product of three normalized wannier functions , i.e. @xmath81 @xcite , and we can write @xmath82 where we have defined the matrix elements @xmath83 and @xmath84 . the values of @xmath85 and @xmath86 as a function of the depth of the optical lattice @xmath87 are shown in fig . both matrix elements are sufficiently large so that the above inequality @xmath88 can be fulfilled if we want to achieve hopping amplitudes @xmath89 of the order of khz . we simplify @xmath90 to find @xmath91 as a function of the depth of the optical lattice @xmath92 . b ) matrix element @xmath86 as a function of the depth of the optical lattice @xmath92 for different values of @xmath93 decreasing with increasing @xmath6 . the inset shows @xmath86 against @xmath6 at @xmath94.[fig3 ] ] the total hamiltonian describing the configuration shown in fig . [ fig2 ] is given by @xmath95 and we will for simplicity assume @xmath96 . in this work we will mainly consider small filling factors of the optical lattice @xmath97 with @xmath98 the average number of particles per lattice site and thus only look at one particle effects neglecting the interaction terms @xmath99 and @xmath42 . then the hamiltonian can be written as @xmath100 this hamiltonian @xmath101 is equivalent to the hamiltonian for electrons with charge @xmath4 moving on a lattice in an external magnetic field @xmath102 @xcite , where @xmath103 is the area of one elementary cell . in the remainder of this paper we will study the properties of @xmath104 for neutral atoms in optical lattices and in particular show that it can be used to study the whole of the hofstadter butterfly shown in fig . we note that we have chosen the detunings of the additional lasers @xmath52 to exactly cancel the term @xmath60 arising from the acceleration or electric field . if these two terms did not cancel the remaining terms resemble a homogeneous electric field . in this section we show how to detect basic properties of the fractal energy spectrum in an experiment . we also briefly discuss the effects of fluctuations in the laser parameters , of finite system sizes , and interactions between the atoms . one way of experimentally identifying the number of energy bands in the case of rational @xmath6 is to measure the time evolution of the particle density @xmath105 in the lattice . we assume the lattice to be loaded from a bose - einstein condensate @xcite neglect any interaction between the atoms and consider only a single atom . the initial wave function of the system is assumed to be @xmath106 a normalization constant . we then turn on the additional lasers to simulate a magnetic field and find the density of particles given by @xmath107 to be independent of @xmath17 . if we choose @xmath108 a periodic interference pattern emerges in the time evolution of @xmath109 . different paths for hopping around in the lattice interfere with periodic phase relations ( cf . fig . [ fig4]a ) . the periodicity of interference pattern is determined by @xmath9 and repeats itself after exactly @xmath9 lattice sites as can be seen in fig . [ fig4]a for @xmath110 . the periodicity is destroyed for values of @xmath6 which are irrational . an example can be seen in fig . [ fig4]b where a value of @xmath111 is chosen which differs by about @xmath112 from @xmath110 . this little change in @xmath6 is sufficient to considerably alter the density of particles in the lattice and to destroy any periodicity . ( in arbitrary units ) as a function of time @xmath113 and spatial coordinate @xmath18 . light ( dark ) areas indicate a large ( small ) particle density . a ) for @xmath110 a periodic particle density with a period of exactly @xmath114 lattice sites emerges . b ) for a value of @xmath111 the periodicity in the particle density disappears and the visibility of the interference fringes decreases . [ fig4 ] ] as discussed by hofstadter @xcite the maximum number of energy bands shown in fig . [ fig1 ] , which can in principle be distinguished in an experiment , depends on the fluctuations in the parameter @xmath6 . in our case these fluctuations are determined by the frequency stability of the lasers and will thus not be significant . in an experiment with neutral atoms the resolution of the energy bands will rather be determined by the size of the whole sample , i.e. by the number @xmath115 where @xmath116 is the size of the whole sample , and by the spatial resolution in measuring interference patterns as described in sec . [ intpatt ] . for large filling @xmath117 the interaction terms in the hamiltonian eq . [ hamil ] , especially the onsite interactions become significant and can not be neglected . we postpone a detailed study of these effects to a further publication and only include a graph of how the ground state in an optical lattice with a superimposed 2d harmonic trap of trapping frequency @xmath118 @xmath119 looks like in the presence of the effective magnetic field . we use mean field theory in the form of the gutzwiller ansatz ( as described in @xcite ) , and numerically solve for the ground state of the system for finite @xmath120 . in fig . [ fig5 ] we plot the particle number fluctuations @xmath121 with @xmath122 and the modulus of the superfluid parameter @xmath123 . the effective magnetic field alters these properties of the ground state significantly in comparison to the case of @xmath22 . the effective magnetic field leads to a decrease of the particle number fluctuations and the superfluid density in the center of the trap which is typical for the onset of a mott - insulating phase even for @xmath124 with @xmath125 the critical interaction strength for the transition to the mott insulator . a similar behavior has already been found in @xcite . in addition we find from the numerics that interference effects lead to point like increase / decraese in @xmath126 and @xmath127 in several of the lattice sites . [ a ) , b ) ] and superfluid parameter @xmath128 [ c ) , d ) ] as a function of @xmath44 and @xmath129 for @xmath130 , @xmath131 and chemical potential @xmath132 . the plots a ) , c ) [ b ) , d ) ] show the case @xmath22 [ @xmath110 ] . light ( dark ) areas indicate large ( small ) values of the functions ( black corresponds to 0 white to 1 ) . [ fig5],width=321 ] in conclusion we have shown that quantum optical techniques allow to implement hamiltonians often used to model charged particles subject to an external magnetic field in a lattice . we have shown that all of the physically interesting parameter regime can be explored by this setup and proposed one method to measure some of the most striking features of the fractal energy bands of the hofstadter butterfly . the setup we have investigated possesses a lot of possibilities for further extensions towards quantum simulations of strongly correlated systems of charged particles like interacting electrons moving on a lattice subject to electric and magnetic fields . the major difference and at the same time one of the most attractive features of the atomic system is a large degree of control that can be exerted by quantum optical means . in comparison to condensed matter systems the hamiltonian describing the system is very well known and the parameters appearing can be controlled and varied over a much wider range than is usually the case for strongly correlated systems . also , the time scale over which these parameters can be changed is short in comparison to decoherence time scales in the system . this allows to study coherent dynamical effects that are not easily accessible in most condensed matter systems . the detailed investigation of such aspects lies beyond the scope of this paper and will be dealt with in future publications . thanks d. feder for discussions . this work is supported in part by the austrian science foundation and eu networks . we describe the configuration for realizing @xmath50 , the realization of @xmath134 is then straightforward if lasers with sufficiently different frequencies to avoid interferences between @xmath50 and @xmath134 are used . two running laser waves with rabi frequencies @xmath135 and corresponding laser frequencies @xmath136 for driving the transitions @xmath137 ( @xmath138 ) with a large detuning @xmath139 are superimposed . we adiabatically eliminate the auxiliary internal level @xmath140 and the resulting rabi frequency for the raman transition between @xmath16 and @xmath15 is then given by @xmath141 where @xmath142 is the wave vector of the laser @xmath135 . both lasers are assumed to be incident in the @xmath13 plane at angles @xmath143 and @xmath144 , respectively . if a @xmath14 component of the wave vectors is avoided the experiment can be done in several identically prepared planes of the lattice simultaneously which enhances the measurement signal . for a given @xmath145 , @xmath146 fulfilling the requirement that @xmath147 we find @xmath148 where @xmath149 . these solutions are only physically meaningful for @xmath150 . since @xmath151 the resulting limitations on possible values of @xmath20 do not constrain possible values of @xmath6 severely . only a negligibly small range of values of @xmath152 will not be realizable due to these constraints . we note that if we allow the lasers to have a @xmath14-component of their wave vector any value of @xmath6 is possible .

we investigate the dynamics of neutral atoms in a 2d optical lattice which traps two distinct internal states of the atoms in different columns . two raman lasers are used to coherently transfer atoms from one internal state to the other , thereby causing hopping between the different columns . by adjusting the laser parameters appropriately we can induce a non vanishing phase of particles moving along a closed path on the lattice . this phase is proportional to the enclosed area and we thus simulate a magnetic flux through the lattice . this setup is described by a hamiltonian identical to the one for electrons on a lattice subject to a magnetic field and thus allows us to study this equivalent situation under very well defined controllable conditions . we consider the limiting case of huge magnetic fields which is not experimentally accessible for electrons in metals where a fractal band structure , the hofstadter butterfly , characterizes the system .

the mode of action of many drugs in clinical use for the treatment of cancer , genetic disorders , and viral diseases is believed to be based on their binding to nucleic acids and subsequent modification of the genetic material [ 1 , 2 ] . the discovery of the double helical structure of deoxyribonucleic acid ( dna ) by watson and crick in 1953 and the subsequent revelations relating to the structural features to the basic functional properties of dna such as replication and transcription have proven the utility of dna as a potential target for the development of biologically active agents [ 4 , 5 ] . ribonucleic acid ( rna ) also play essential role in normal biological process as well as in the progression of many diseases that led to growing interests in exploiting in designing of new class of therapeutics [ 68 ] . a number of small organic molecules are endowed with cytotoxic properties that are exerted through highly specific but noncovalent and reversible interactions with nucleic acid structures [ 913 ] . intercalation occurs when planar aromatic molecules are sandwiched between two adjacent base pairs of nucleic acids . nonintercalative binding occurs in the major or minor grooves of nucleic acids without inserting any part of the binding molecule between base pairs . the physical and molecular basis of binding of natural alkaloids to nucleic acids has been a subject of extensive study in the recent past [ 1417 ] . elucidation of the nature , strength and energetics of these interactions may reveal the molecular basis of many antitumor and antiviral natural products and provide helpful guidance for rational drug design of new potential chemotherapeutic agents . the intercalating ligands constitute one of the most widely studied groups as they form important class of compounds for cancer therapy . in this context , considerable attention has been paid to naturally occurring protoberberine and benzophenanthridine alkaloids for their low toxicity and wide range of biological activities that include antimicrobial , antileukemic , anticancer , and topoisomerase inhibitory activities [ 1926 ] . this review focuses on the complex formation of two groups of isoquinoline alkaloids with various polymorphic nucleic acid structures in relation to their anticancer activities . these alkaloids ( figure 1 ) include berberine , palmatine , and coralyne of the protoberberine group , sanguinarine of the benzophenanthridine group , and some of their derivatives . it is generally recognized that the most sensitive target for the inhibition of rapidly proliferating cancer cells are those molecules involved in aspects of dna function , especially dna itself . it is , therefore , not surprising that most clinically useful anticancer compounds act against such targets . in this context , significant attention has been focused on the dna binding properties of protoberberine group of alkaloids that constitute an important class of isoquinoline alkaloids widely present as active constituents of folk medicines used world over for centuries . several protoberberine alkaloids and their derivatives have been investigated as potential antitumor agents , among which berberine , palmatine , and coralyne ( a synthetic analogue of berberine ) represent the most intensively studied molecules . the physicochemical properties of protoberberine alkaloids presented in table 1 provide an understanding of the similarity and differences in their chemical structures ( figure 1 ) and properties . the basic skeleton of the quaternary protoberberine moiety is 5,6-dihydro[a , g ] quinolizinium . in berberine , there is an addition of 2,3-methylenedioxy and 9,10 dimethoxy group to the above basic structure and thus the structure of berberine becomes 7,8,13,13a - tetrahydro-9,10-dimethoxy and 2,3 methylenedioxy berberinium . on the other hand , palmatine has the same tetracyclic structure ( 7,8,13,13a - tetradehydro-9,10-dimethoxy-2,3 , methylene dioxy berberinium ) as berberine but differs by the nature of the substituents at position 2,3 on the benzo ring ; being dimethoxy for palmatine . similarly coralyne has the basic structure with a methyl group attached to the c8 position . notably , while berberine and palmatine have buckled structures , coralyne has a planar structure . in aqueous condition , the absorption spectra of berberine and palmatine are similar while that of coralyne is remarkably different . both berberine and palmatine have weak intrinsic fluorescence emission spectra while coralyne has a strong fluorescence emission spectrum in aqueous and alcoholic media . berberine , palmatine , and coralyne are achiral molecules as evidenced from circular dichroism spectroscopy . it exhibited ph dependent structural equilibrium between the iminium ( charged ) and the alkanolamine ( neutral ) forms with a pka value of 7.4 . sanguinarine existed almost exclusively as iminium and alkanolamine forms in the ph rang 1.06.0 and 8.511.0 , respectively . one interesting point to be noted is that the fluorescence of alkanolamine form is more intense than that of iminium form . the most convenient tool for detecting the complex formation between nucleic acids and small molecules is absorbance spectra . like many other small molecules that bind nucleic acids , berberine has by virtue of heterocyclic structure visible absorption band where dna does not contribute and hence is convenient to monitor the binding . the complex formation essentially involves bathochromic and hypochromic effect on its absorption spectrum with clear isosbestic points indicating the onset of equilibrium binding . the bathochromic shift of the spectrum of the free alkaloid on interaction with dna indicates the binding of individual alkaloid to dna substrate , that is , no aggregation prevails . moreover , such red shift presumably arises from the strong intermolecular interaction involving the effective overlapping of the electronic cloud of the base pairs of dna with that of the alkaloid . again , the less polar environment of the bound ligand can cause the hypochromic effect on the free absorption spectrum of the ligand and intercalative positions are hydrophobic in nature . a large number of studies reported the complexation of berberine with calf thymus dna possibly by a mechanism of partial intercalation [ 15 , 16 ] and references therein . [ 30 , 3638 ] have first demonstrated the base and sequence specificity of berberine from studies with several naturally occurring and synthetic dnas of differing base composition and sequences as evidenced from hypochromism and bathochromism in the absorption spectrum ( figure 2 ) , remarkable enhancement of steady - state fluorescence emission intensity , stabilization of dna against thermal denaturation , and perturbation in the circular dichroism spectrum . berberine increased the contour length of sonicated rod like duplex b - dna depending on base composition and induced the unwinding - rewinding process of covalently closed superhelical dna with an unwinding angle of 13. using high - field nmr , saran et al . first proposed that berberine binds to double helical calf thymus dna by a mechanism of partial intercalation in which the planar isoquinoline moiety remained intercalated between base pairs . the partial intercalation model was further substantiated from several analytical techniques that included absorption , fluorescence , isothermal titration calorimetry , differential scanning calorimetry , electrospray ionization mass spectroscopy , in combination with computer molecular modeling studies [ 27 , 4043 ] . however , a fluorescence spectral study of berberine with calf thymus dna and a high - resolution hnmr and uv spectroscopy in conjunction with molecular modeling studies on berberine binding to various short oligonucleotide duplexes ( b - form ) favoured a groove binding geometry . this suggested that berberine is located in the minor groove with a preference for at sequences , lying with the convex side on the helix groove where the positively charged nitrogen atom is close to the negative ionic surface of the oligonucleotide helices . zhu et al . supported the interaction of berberine with b - dna by partial intercalation in which isoquinoline part intercalated in presence of -cyclodextrin . however , chen et al . studied the interaction of berberine with several double stranded oligonucleotides [ d(aagaattctt)2 , d(aaggatcctt)2 , and d(aagcatgctt)2 using electrospray ionization mass ( esi - ms ) and fluorescence spectroscopic techniques to establish the sequence selectivity and preference of binding to these structures . the results from esi - ms and fluorescence titration experiments indicated that the sequence selectivity of berberine was not significant and remarkable at rich dna binding preference was not observed . it is known that alternating gc polymer and its methylated analogue structures assumes left - handed conformation ( z - dna ) in high molar salt ( na , k ) , in low molar divalent cations ( ca , mg , ni ) , micromolar concentration of hexamine cobalt chloride , and millimolar concentration of polyamines . in order to analyze the binding of berberine to z - form dna , kumar et al . reported that z - dna structure remained invariant in the presence of berberine up to a nucleotide phosphate /alkaloid molar ratio of 0.8 and suggested that berberine neither bound to z - form dna nor converted the z - dna to the bound b - form structure like other intercalators . the molecular architecture of the h - from dna appears to be unique , stable left - handed structure with hoogsteen base pairs , is distinctly different from the right - handed b - dna and left - handed z - dna [ 15 , 16 ] . the binding of berberine to h - dna was found to be non - cooperative resulting in perturbation of the circular dichroism spectrum and generation of extrinsic circular dichroism bands with opposite sign and magnitude compared to the b - form dna . it was suggested that berberine could be used as a probe to detect the alternation of structural handedness due to protonation and may potentiate its use in regulatory roles for biological functions . the formation of intermolecular triplex offers a means of achieving sequence specific recognition of duplex dna forming specific hydrogen bonds . although the third strand oligonucleotide possesses specific sequence recognition properties , the binding is not so strong which results in a relatively low stability of the triplex structure . the instability of triple helical structures under normal physiological conditions is a critical limitation that restricts their uses in vivo . several intercalating ligands have now been reported that can preferentially stabilize triplex structures [ 5055 ] . ren and chaires have shown that berberine preferentially and very strongly bound to txa.t triplex compared to at duplex using novel competition dialysis and thermal melting experiments.recently das et al . demonstrated that berberine stabilized the hoogsteen base - paired third strand of txa.t triplex without affecting the watson - crick strands as revealed from thermal melting ( figure 3(a ) ) and circular dichroic studies ( figure 3(b ) ) and proposed that it binds to the third strand presumably by mechanism of intercalation . thermodynamics of berberine - triplex complexation revealed that the binding process was exothermic and entropy driven favouring a tight binding at the intercalation site . in recent years , recognition that certain sequences promote formation of higher - order structures of dna has revealed new targets for chemotherapy [ 5860 ] . these structures can form the association of four single strands containing tracts of guanine bases ( tetramer ) , and can also arise within one or two strands containing several of these sequences as the strands fold back upon themselves . in order to understand the potential of quadruplex dna as a chemotherapeutic target , guanine rich sequences with the ability to form quadruplex structures are found in telomeres at the end of eukaryotic chromosomes ( ttaggg repeats in humans ) as well as in promoter regions of genes and in recombination sites [ 61 , 62 ] . the observations that telomerase is expressed in malignant but not normal tissues led to the paradigm that drugs that interfere with the action of telomerase could be expected to cause the death of cancer cells . if interactions of telomeric proteins with specific sequences of telomeric dna are lost , this also leads to cell death by apoptosis . this suggests that compounds that bind to dna and inhibit protein binding would cause the rapid death of tumor cells . compounds that stabilize quadruplex dna , presumably preventing interactions with proteins have been shown in vitro to inhibit telomerase . recent studies show that berberine inhibits telomere elongation and binds strongly to various g - quadruplex dna structures and inhibits telomerase activity [ 50 , 67 ] . thus berberine may be used as a target to probe for g - quadruplex dna for its development as potential antitumor drugs . palmatine is structurally similar to the well - known isoquinoline alkaloid berberine . to evaluate the affinity and mode of binding to b - dna , kluza et al . and bhadra et al . reported that addition of calf thymus dna caused marked changes in the absorption spectrum of palmatine ( figure 4 ) with strong hypochromic and bathochromic shifts , with well - resolved isosbestic points , and with increased thermal melting temperature to form stable complexes with b - dna . further from electric linear dichroism studies , it was interpreted that palmatine binds either by an intercalation or by an external stacking parallel to the base pairs . however , an earlier study by yu et al . proposed a nonintercalative binding of palmatine . recently , the author 's laboratory demonstrated the base and sequence - dependent binding of palmatine and established that palmatine formed a partial intercalation complex with all the polymers except the homo and heteropolymer of gc , with which it formed a nonintercalative complex . the binding of palmatine to calf thymus dna was further characterized by thermodynamic studies using isothermal titration calorimetry and the binding process was exothermic and entropy - driven which favour the intercalative mode of binding . it does not bind to z - dna nor does it convert z - form to b - form . to date there is no report on the binding of palmatine to higher - order dna structures , triplexes , and quadruplexes and study in this direction is awaited . another important alkaloid of protoberberine group is the synthetic molecule coralyne , which was found to be potentially capable of intercalating with b - dna [ 32 , 73 , 74 ] and the results led to the assumption that the dna binding may be correlated with biological activity . it was reported that at a lower molar ratio of coralyne to b - dna , an intercalating complex by stacking along the backbone of dna , while at higher molar ratios , a dna - induced aggregation occurred . although a wealth of data [ 32 , 73 , 74 ] is presently available regarding the complex formation between coralyne and b - dna , the interpretation of these data needs to be performed with caution as coralyne exhibits a high tendency of aggregation in aqueous buffer even at very low concentrations . maiti et al . first addressed this problem and showed that aqueous solutions containing 30% ( v / v ) ethanol suppressed the aggregation of coralyne and allowed spectrophotometric titration of a fully monomeric form with calf thymus dna . the base and sequence specificity of coralyne ( monomeric ) on binding to various naturally occurring and synthetic b - dna were studied by spectrophotometric and spectrofluorimetric titrations , circular dichroic spectroscopy , thermal melting , isothermal titration calorimetry , and viscometric studies . the results of spectrophotometric and calorimetric studies of a fully monomeric form of coralyne with calf thymus dna is presented in figures 5(a ) and 5(b ) , respectively . coralyne increased the contour length of sonicated rod like duplex b - dna and induced the unwinding and rewinding process of covalently closed superhelical b - dna with an unwinding angle of 21. these experiments revealed that monomeric coralyne binds to b - dna by a mechanism of intercalation with a relatively high specificity toward alternating gc sequences . comparative spectroscopic and thermodynamics binding parameters for the interaction of isoquinoline alkaloids with calf thymus dna are presented in tables 2 and 3 , respectively . recently , it has been reported [ 28 , 75 ] that coralyne , unlike other classical intercalators , binds to z- form dna without converting the bound form to the b - form bound structure as revealed from circular dichroic spectroscopy . studies indicated that coralyne could be used as a probe to detect the z - form structure in vivo . coralyne showed strong perturbation of circular dichroic spectrum of h - form dna ( figure 6 ) . however , the mode and mechanism of binding of coralyne - h - dna complexation could not be revealed from these studies . in addition , coralyne was shown to bind to parallel triplex dna but it does not bind to antiparallel triplex dna . it was concluded from early experiments using thermal denaturation analysis and spectrophotometric titration with txa.t and cxg.c containing dna triplexes that coralyne does not exhibit significant sequence selectivity during triplex complexation . a later study , however , using various techniques like dnase foot printing , thermal denaturation analysis , spectrophotometric titration and circular dichroic , as well as nmr spectroscopy , showed a preferential intercalation of coralyne into txa.t triplexes , whereas in cxg.c triplexes , the coralyne molecule was only partially intercalated due to the electronic repulsion between the cationic alkaloid and protonated cytosine . the high propensity of coralyne to stabilize triplex dna has been demonstrated by hud et al . [ 55 , 82 ] from the observation that duplex poly(dt)poly(da ) is transformed into a mixture of poly(dt)xpoly(da)poly(dt ) triplex and single stranded poly(da ) in presence of coralyne at slightly elevated temperature ( t > 37c ) . this disproportionation reaction of double - stranded dna has been rationalized in terms of the formation of a highly stable intercalation complex between coralyne and triplex dna . further , they demonstrated that coralyne may act as a template for the formation of an antiparallel dna triplex from homoadenine sequences . it was shown that coralyne has the ability to induce and stabilize various g - quadruplex structures including human g - quadruplex as well as its efficiency in inhibiting telomerase . the thermal stabilization of a preformed intermolecular g - quadruplex structure shows that coralyne and berberine is able to stabilize rather than to induce g - quadruplex intermolecular structure . in both cases , coralyne is the most active component possibly due to its fully aromatic core and it is the most efficient telomerase inhibitor . among the benzophenanthridine alkaloids , sanguinarine , an isoquinoline plant alkaloid , is known to generate a wide variety of biochemical and pharmacological effects including its use in cancer prevention . the physical and molecular basis of the binding of sanguinarine with canonical b - dna were first demonstrated by maiti et al . [ 33 , 34 , 8488 ] using various physicochemical techniques like absorption , fluorescence , circular dichroism , thermal melting , viscometry , calorimetry , and nmr spectroscopy . on binding to b - dna structures , the absorption spectrum of sanguinarine underwent bathochromic and hypochromic changes exhibiting clear isosbestic points ( figure 7(a ) ) , the steady - state fluorescence emission intensity quenched , thermal melting temperature of b - dna shifted to higher temperatures and there were strong perturbations of circular dichroic pattern of b - dna . sanguinarine induced the unwinding process of covalently closed superhelical plasmid b - dna with an unwinding angle of 27. the binding of sanguinarine to calf thymus dna was also investigated by hnmr and all the proton resonances in the molecule were assigned using a combination of 2d cosy , nosey , and rosey techniques . all these experiments conclusively suggested that it binds b - dna by a mechanism of intercalation . the sequence selective binding of sanguinarine to b - dna was also studied by waring group using dnase foot printing technique and a mixed nucleotide sequence binding for sanguinarine - dna complex formation was proposed . recent calorimetric studies of sanguinarine calf thymus dna complexation ( figure 7(b ) ) showed the binding process to be exothermic and enthalpy driven . binding and thermodynamic parameters of sanguinarine calf thymus dna complexation obtained from isothermal titration calorimetry are presented in table 3 . a recent study showed that sanguinarine also binds to single pyrimidine bulges in hairpin sequences . the interaction of sanguinarine with z - dna structure was first studied by das et al . . it was demonstrated that on addition of the alkaloid to the z - form structure , a direct conversion of the z - form toward the characteristic right - handed bound complex without forming any intermediate forms was observed . sanguinarine bound strongly to b - form in a noncooperative manner while its binding to z - form was highly cooperative and 2 - 3 base pairs of z - form switched to the right - handed form for each bound sanguinarine molecule . the interaction of sanguinarine with h - form showed that it does not bind to h - form structure , but it converted the structure to the bound right - handed b - form [ 94 , 95 ] . here also approximately 2 - 3 base pairs of the h - form switched to the right - handed bound b - form for each bound molecule of sanguinarine . first demonstrated that sanguinarine binds to poly(dt)poly(da)xpoly(dt ) but only weakly to poly(dc)poly(dg)xpoly(dc ) more quantitatively and reported that sanguinarine binds to triplexes by intercalation in a noncooperative manner and it stabilized the hoogsteen base paired third strand of dna compared to their watson - crick strands . thermodynamic study revealed that the process of binding of sanguinarine to poly(dc)poly(dg)xpoly(dc ) triplex was exothermic and enthalpy - driven while that to poly(dt)poly(da)xpoly(dt ) triplex was exothermic and entropy - driven . the binding constants and thermodynamic parameters of berberine , coralyne , and sanguinarine complexation to various triplexes are presented in table 4 . reported that sanguinarine can form a complex with g - quadruplex telomere dna as revealed from dna polymerase stop assay , uv melting , electrospray mass spectroscopy , and circular dichroism studies which may potentiate a strategy for structure - based anticancer drug design targeting human telomeres . rnas are versatile molecules that are now known to play an essential role in normal biological process and in the progression of several serious human diseases like hiv and hepatitis c virus ( hcv ) , and so forth which has led to growing interest in exploiting rna as a cellular target for therapeutic drug design . the recent discovery of a number of micro rnas and the knowledge of their functions further reiterated the critical and diverse roles played by rna in cell biology [ 98 , 99 ] . ribosomal rna ( r - rna ) has long been known to be the receptor for antibiotics and antisense oligonucleotides are being used to downregulate gene expression . new drugs could potentially be designed to bind to unique structural regions in mrna and thereby regulate gene expression . virtually all mrnas formed in eukaryotic cells have a poly(a ) tail of approximately 200250 adenosines at the 3'end . the long poly(a ) tail is an important determinant of mrna stability and maturation , and is essential for the initiation of transcription [ 101 , 102 ] and the production of alternate forms of proteins [ 103 , 104 ] . the structure of poly(a ) has been established to exist as a single - stranded helix stabilized by pair - wise stacking interaction between adjacent adenines at physiological ph and temperature [ 105 , 106 ] . poly(a ) polymerase ( pap ) catalyses 3'-end poly(a ) synthesis , participates in an endonucleolytic cleavage step and is one of the key factors in polyadenylation of the 3'end of mrna . neo - pap , a recently identified human pap , is significantly overexpressed in human cancer cells in comparison to its expression in normal or virally transformed cells [ 107 , 108 ] and may represent a tumor - specific target . small molecules capable of recognizing and binding to the mrna - poly(a ) tail might interfere with full processing of mrna by pap and would represent a new type of potential therapeutic agent . in this context , several years ago maiti et al . first observed a preferential binding of berberine to poly(a ) structure over b - dna and trna and reported that the binding affinity of berberine to poly(a ) was approximately 12 times higher than b - dna and approximately 100 times higher than t - rna molecules . recently , they investigated the mode , mechanism , and energetics of berberine binding to poly(a ) structure in details . it was suggested that berberine binds strongly to single - stranded poly(a ) structure by a mechanism of partial intercalation and the binding was found to be endothermic and entropy driven . studied the interaction of palmatine with poly(a ) using various biophysical techniques and their results also showed a strong affinity of palmatine to poly(a ) . the energetics of this strong binding of palmatine to poly(a ) was found to be exothermic and enthalpy - driven . . showed that coralyne binds to single - stranded poly(a ) helix and induced the formation of a self - structure in poly(a ) . depending on solution conditions such as ph , salt and temperature , single - stranded poly(a ) can adopt a parallel double stranded conformation formed by the pairing of adenine bases at the n1 position [ 111 , 112 ] . the possibility of the formation of such a double stranded poly(a ) in eukaryotic cells was hypothesized to result in the termination of the polyadenelation process . small molecules that could bind strongly to single - stranded poly(a ) may be useful as potential leads for controlling the mrna - poly(a ) chain elongation and in turn mrna degradation as well as the conversion of single - stranded poly(a ) to double stranded poly(a ) that may open up an opportunity for modulating nucleic acid structure - functions . the plant alkaloids berberine and palmatine exhibit stronger binding to single stranded poly(a ) , but do not induce any self - structure formation in poly(a ) helix [ 109 , 114 ] . binding of coralyne to the poly(a ) helix leading to self structure formation was further supported by giri and kumar and the binding process was found to be predominantly exothermic and enthalpy - driven with a stoichiometry of one coralyne per four adenines bases . sanguinarine was also found to bind very strongly to single stranded poly(a ) [ 71 , 78 ] and induce unique self - structure in poly(a ) . the alkaloid binding process was exothermic and predominantly enthalpy - driven as revealed from isothermal titration calorimetry . comparative circular dichroic spectrum of poly(a ) treated with various alkaloids are shown in figure 8 . spectroscopic studies showed that among the four alkaloids , the affinity of binding of berberine , palmatine , and coralyne to poly(a ) helix is one order lower than that of sanguinarine . thus , the very strong binding of sanguinarine to poly(a ) leading to self structure formation may open up a new avenue for the use of this natural product in modulating the gene expression and development of anticancer agent . topoisomerases are nuclear enzymes that act on the topology of dna . it was first discovered by wang . there are three main types of dna topology ; supercoiling , knotting , and catenation . when outside of replication or transcription , dna needs to be kept as compact as possible and these three states help this cause . however , when transcription or replication occurs , dna needs to be free and these states seriously hinder the process . ( topo i ) changes the degree of supercoiling of dna by causing single strand breaks and religation whereas topoisomerase ii ( topo ii ) causes knotting , catenation and decatenation of dna by passing the double - stranded dna helix through a transient double - stranded break and then resealing in the strand break [ 118 , 119 ] . the difference roles of dna topo i and ii may indicate an opposing pair of roles in the regulation of dna supercoiling . both activities are especially crucial during dna transcription and replication , when the dna helix must be unwound to allow proper function of large enzymatic machinery . recently , two more topoisomerases have been discovered and these are namely topoisomerase iii and topoisomerase iv . topoisomerase iii enzymes are implicated in regulation of recombination events while topoisomerase iv has roles in the process of segregating newly replicated chromosomes . dna topoisomerases topo i and topo ii represent the molecular target of many anticancer drugs . fewer topo i inhibitors have been discovered than topo ii inhibitors and a large number of them including the anthracyclines have been used as anticancer agents before identification of topo ii as their target . these inhibitors are chemotherapy agents designed to interfere with the action of topoisomerase enzymes that control the changes in dna structure by catalyzing the breakage and rejoining of the phosphodiester backbone of dna strands during the normal cell cycle . in recent years , topoisomerase inhibitors have become popular targets for cancer chemotherapy treatments . it is thought that topoisomerase inhibitors block the ligation step of the cell cycle , and that topo i and topo ii inhibitors interfere with the transcription and replication of dna by upsetting proper dna supercoiling . topo i has been established as an attractive molecular target for anticancer drugs , primarily due to the discovery of camptothecin ( cpt ) a naturally occurring plant alkaloid for its successful development as an anticancer drug with a unique mode of action , that is , inhibition of dna topo i , which added an entirely new dimension to the fields of chemotherapy . thus , developing compounds that are capable of poisoning the topoisomerases have emerged as an attractive approach for the search of novel cancer chemotherapeutic agents [ 122126 ] . for drugs [ 127 , 128 ] that target topo ii intercalation into the host dna duplex to understand the role that ligand - dna interactions play in topo i poisoning li et al . have characterized and cross correlated the topo i poisoning and dna binding properties of various families of structurally related dna binding protoberberine alkaloids ( figure 9 ) . these four analogues differ with respect to the chemical substituents on their a- and d - rings . their dna binding data reveal that protoberberine alkaloids intercalate into duplex dna while unwinding the host dna by 13. in addition , the data showed that modification of the d - ring alter both dna binding affinity and topo i poisoning activity . the modifications of the a - ring on the other hand have a negligible impact on dna binding affinity but exerted a profound influence on topo i poisoning activity . these structure - activity relationships are consistent with a model for topo i poisoning by protoberberines in which both alkaloid - dna and alkaloid - enzyme interactions are necessary for stabilization of the ternary ( topo i - dna - alkaloid ) cleavable complex ( figure 10 ) . it is suggested that an ensemble of both alkaloid - dna and alkaloid - enzyme interaction may be of general importance for alkaloid - induced poisoning of topo i. berberine , palmatine , and several of its derivatives were shown to act as mammalian topo i and topo ii inhibitors although weakly , while coralyne and many of its derivatives were found to be strong inhibitors of dna topo i . both berberine and palmatine did not affect the dna cleavage relegation reaction catalyzed by topoisomerases . this lack of effect most likely accounts for the presence of a methoxy substituent at 9-position , which prevents hydrogen bonding interactions with guanine residues . the most significant aspect of coralyne is its ability to inhibit dna relaxation in a fashion significantly similar to the most potent antitumor alkaloid cpt . wang et al . demonstrated that coralyne and several of its derivatives ( figure 11 ) including the partially saturated derivative , 5,6-dihydrocoralyne ( c2 ) were tested for their ability to induce single - stranded cleavage by formation of ternary complexes with plasmid dna and topo i. it was observed that all the derivatives ( c1c11 ) induced cleavage in plasmid dna but are not as effective as coralyne ( c1 ) or 5,6-dihydrocoralyne ( c2 ) and stabilize the complex between topo i and dna . however , coralyne ( c1 ) was more effective than 5,6-dihydrocoralyne ( c2 ) at lower concentration . in a subsequent study , pilch et al . confirmed that 8-desmethylcoralyne ( c3 ) and 5,6-dihydro-8-desmethylcoralyne ( c11 ) may act as topo i poison , whereas no topo ii poisoning properties were observed . more recent immunocytochemical studies in mcf-7 breast cancer cells showed that sanguinarine induces a striking disruption of normal cyclin and topo ii trafficking which inhibited the proliferation of transformed cells . although great attention is currently focused in unraveling the molecular , cellular , and genetic process that lead to cancer , this knowledge has not been translated into effective new cures for the disease . recent report of american cancer society ( december 2007 ) showed that 7.6 million people died from various types of cancers . apart from humans , other animals and plants may also be affected by cancer . in general , cancer defines diseases , in which abnormal cells divide without control that have the capacity to invade surrounding normal tissue , can spread to other parts of the body through the blood and lymph systems and kill the host in which it originates . for the last several years , it was observed that the incidence of some types of cancer increases with age . therefore , as the life span of humans has increased , the incidence of neoplastic diseases has also increased . carcinoma is the cancer that begins in the skin or in tissues that line or cover internal organs . sarcoma is the cancer that begins in bone , cartilage , fat , muscle , blood vessels , or other connective or supportive tissue . leukemia is the cancer that starts in blood - forming tissue , such as bone marrow , and causes large numbers of abnormal blood cells either produce or enter the blood . lymphoma and multiple myeloma are cancers that begin in the cells of the immune system . central nervous system diseases are cancers that begin in the tissues of the brain and spinal cord . adrenocortical carcinoma disease is cancer that forms in the outer layer of tissues of adrenal glands . breast cancer forms in tissues of the breast , usually the ducts and lobules of women . fibroids are common tumors of the uterus ( womb ) found in about 20% of young women and they form ball - like and may vary in size from pin to very large size . lung cancer is a disease that forms in tissues of the lung , usually in the cells living air passages . lung cancer is one of the leading causes of cancer - related death throughout the world . despite of the advances in current therapeutic approaches for lung cancer , including surgery , radiotherapy , and chemotherapy , the overall survival rate of the patients with lung cancer has been static for the past two decades . improvement in curability and survival is dependent on advances in early detection , surgery , radiotherapy , and chemotherapy ; but once widespread metastatic disease has become established , chemotherapy is a central component of management . chemotherapy is the treatment of cancer with drugs ( anticancer drugs ) that can destroy cancer cells . in current usage , the term chemotherapy usually refers to cytotoxic agents that affect rapidly dividing cells in general . several antitumor antibiotics and plant alkaloids are the more recent clinically effective antitumor cytotoxic drugs , which act by disrupting the structure of duplex b - dna , thereby affecting their interaction with proteins that are important in dna replication , repair , or transcription . investigation into the mechanism of action of plant - derived compounds with low toxicity remains an important approach in the search for new and more effective anticancer agents . protoberberine and benzophenanthridine group of alkaloids possessing broad range of biological activity [ 138146 ] are widely distributed in several botanical families and are used in traditional chinese and ayurvedic medicine for many centuries . berberine is found in the roots of rhizomes of several families of plants ; goldenseas , coptin , oregon grapes , barberry , tree turmeric , yerba mansa , among others and possess antitumor activities [ 147 , 148 ] . it exhibits potent in vitro antitumor activity against sarcoma s180 cells with inhibition of the biosynthesis of dna , rna , and proteins . it was evident that berberine interfered with all these biochemical process ( table 5 ) . however , the synthesis of rna and protein was most sensitive to the alkaloid at 40 ug / ml . dna and protein biosynthesis were examined further by incorporation of thymidine [ h ] into dna and glycine [ c ] into protein in s180 cells in vitro and dose response curves was shown in figure 12 . creasey reported that the in vivo 30-minutes treatment with berberine on tumor bearing mice ( 10 mg / kg ) before injection of thymidine [ h ] or glycine [ c ] had only minimal effects on the incorporation of these precursors into dna and protein , respectively , and inhibition was found to be only 17% for protein and 14% for dna . however , when cells were harvested 30 minutes after treatment with berberine and then incubated with glycine [ c ] and thymine [ h ] in vitro incorporation into protein and dna ( figure 12 ) was reduced by 85% and 45% , respectively . kuo et al . observed an increase of g2/m phase population in berberine - treated hl60 cells . it modulates expression of mdr1 gene product in track cancer cells and was identified as a potential inhibitor for caspase 3 , a major apoptosis effector . it was also reported that berberine downregulates k - ras 2 gene expression in human embryonic carcinoma cells . wu et al . demonstrated that berberine - induced apoptosis of human leukemia hl60 cells with downregulation of nucleophosmin / b23 and telomerase activity . linked its cytotoxic activity to a duel topo i and topo ii poisoning activity . for management of skin cancers , montena et al . for the first time demonstrated in vitro treatment of human epidermoid carcinoma a431 cells with berberine that decreased cell viability , induced cell death in dose - dependent manner which was associated with an increase in g1 arrest and suggested berberine to be used as chemotherapeutic drug against human epidermoid carcinoma a431 cells . the effect of berberine on human malignant brain tumor esopharyngeal cancer and human leukemic and human colon cancer cell lines was tested , where a significant killing effect was achieved [ 156 , 157 ] . subsequently , szeto et al . investigated the cytotoxicity and the dna damage effect on npc / hk-1 cells after berberine treatment and evaluated the possibility of dna repair in this cell line . their studies showed that berberine , at 5200 m induced cell death in a dose dependent manner . treatment of cells with 200 m berberine for 5 hours yielded 60% drop of cell viability ( figure 13).the comet assay was employed after berberine treatment ( 5 to 200 m ) . the damaged cells were not able to be repaired as indicated by the increase in tail dna content ( figure 14 ) . furthermore , berberine was observed mainly in the cytoplasmic region of npc cells at 2 hours of incubation at 200 m as examined under a fluorescent microscope ( figure 15 ) . again , berberine has been found to be near the nuclear region and able to bind with dna and may inhibit dna topoisomerase ii . therefore , inhibition of dna repair ability and stability may also contribute to the cytotoxic effect on the cancer cells . the dna damaging effect and the inhibition of dna repair contributed to the cytotoxic activity in the cancer cells may be part of the mechanisms of action of berberine on cancer cells . berberine also displayed alterations in cell cycle progression , dna synthesis , cell proliferation , and cell death in melanoma cells k1735-m2 mouse and wm 793 human melanoma malignant cell lines which were correlated with the concentration and intracellular distribution of the alkaloid and suggested that it may be used in clinical development of a cytotoxic compound . moreover , berberine was shown to inhibit telomere elongation , and bind to various human g - quadruplex structures inhibit telomerase . berberine has been found to be useful for the treatment of lung cancer patients and the correlation between the overexpression of ap - i and lymphatic metastasis has been reported . combined treatment with berberine and an anticancer drug camptothecin analogue , cpt - ii resulted in a marked inhibition of the tumor growth at the implantation site and of lymphatic metastasis , as compared with either treatment alone . berberine also exhibited dose - dependent antiproliferative effects of the human promonocytic u937 cells and induced significant changes in mitochondrial membrane potential of the tumor cells . in a recent study , the effects of berberine on the human promyclocytic leukemia hl60 cells and on the murine mylomonocytic leukemia weh1 - 3 cells suggested berberine induced g2/m arrest in both the cells via the inhibition of cyclin b1 and the promotion of wee1 . the treatment of human prostate cancer cells ( pc-3 ) with berberine revealed that berberine - mediated cell death of human prostate cancer cells was regulated by reactive oxygen species and suggested that berberine may be considered as a promising therapeutic candidate for prostate cancer . berberine was assessed for the anti - human cytomegalovirus ( hcmv ) activity using the plaque assay . it was suggested that berberine inhibited the replication of hcmv that was presumed to interfere with intracellular events after virus penetration into the host cells and before viral dna synthesis . berberine showed inhibition of reverse transcriptase activity of rna tumor viruses and the results were correlated with its antileukemic activity . the enzyme cyclooxygenase - z ( cox-2 ) is abundantly expressed in colon cancer cells and plays a key role in colon tumerogensis . compounds inhibiting cox-2 transcriptional activity have therefore potentially a chemopreventive property against colon tumor formation . fukuda et al . have reported that berberine effectively inhibits cox-2 transcriptional activity in colon cancer cells in a dose - dependent manner at concentrations higher than 0.3 m . the inhibitory activity of berberine on cox-2 promotor activity is not simply due to the direct inhibition of macromolecular synthesis in the cells . in addition , reactive oxygen intermediates play a role in the expression of cox-2 and cox-2 promotor activity is regulated by interactions of diverse transcription factors and intracellular messages . it has been reported that cox-2 overexpression is associated with the acquisition of resistance to apoptosis in intestinal epithelial cells . it is likely that inhibition of cox-2 promotor activity may be associated with antitumor and cytostatic / cytocidal effects of berberine . palmatine has been found in the roots , rhizomes , and stem bark of many species of berberidaceae , papaveraceae , fumararaace , menispermaceae , rutaceae , raunculaece , and other plant family . palmatine has been used as folk medicine for centuries due to its immense pharmacological properties . the medicinal plants containing palmatine have been used in the treatment of jaundice , dysentery , hypertension , inflammation , and liver diseases [ 174 , 175 ] . coralyne has been shown to exhibit significant antileukemic activity against both p388 and l1210 leukemia cells in mice [ 74 , 176 ] . although its antitumor activity is not very high , coralyne represents a promising lead structure because of its low toxicity [ 177 , 178 ] . it was shown that irradiation of superhelical plasmid dna in the presence of coralyne leads to an efficient single - stranded cleavage even upon exposure to sunlight . thus photodamaging again , the photoinduced cleavage may be used for the introduction of dna lesions in triplex and quadruplex dna because coralyne exhibits a remarkable propensity to bind to these higher - order dna structures [ 67 , 68 , 81 ] . in particular , the photoinduced damage of the triplex dna may be of interest to those therapeutic approaches in which the selective attack of triplex dna is the key process . the quaternary benzophenanthridine alkaloids which are mainly distributed in the plants of the papaveraceae , rutaceae , fumariaceae families have been the focus of increasing attention for their diverse biological activities . among this group of alkaloids , sanguinarine possesses potent anticancer [ 179182 ] , promising apoptosis activities , as well as cytotoxic effects . in fact , the plants containing sanguinarine have been widely used as chinese medicines and folk medicines for the treatment of human cancer and other diseases . in the uk and usa , sanguinarine has been in use in mouthwashes and toothpastes to inhibit dental plaque and inhibit gingival health . the potential anticancer activities of sanguinarine may be attributed to its binding of chromosomal dna . studies have revealed that in physiological conditions , both iminium and alkanolamine forms of the alkaloid exist because they all exhibit ph - dependent structural equilibrium between these two forms [ 87 , 88 , 185 ] . alkanolamine form was reported to have larger cellular availability than iminium form due to its greater lipophilicity . maiti et al . studied the interaction of sanguinarine with b - dna under various environmental conditions ie salt molarity , ph , etc . and suggested that sanguinarine may be useful as a potential antitumoral agent . this proposal was found to be true when an in vitro study of cytotoxicity of sanguinarine using cancer cell lines and primary cells from oral human tissues established the potential use of sanguinarine for the inhibition of growth of s - g gingival epithelial cells and kb carcinoma cells , and correlated with its complex formation with dna . studied the effect of sanguinarine on proliferation of the s - g cells exposed for 1 to 3 days as shown in figure 16 . it was noted that linear increase in growth was significantly affected with increasing concentration of sanguinarine and no growth was observed after 3 days of exposure to sanguinarine at 5.1 m or greater concentration . as assessed by dna quantification , s - g - cells maintained continuously inhibition of growth increasing concentration of sanguinarine from 1.7 m to 8.5 m may reflect the ability of sanguinarine to intercalate dna . sanguinarine has been reported to possess the potential for selective / preferential elimination of cancer cells without affecting normal cells [ 180 , 187 ] . the study of differential effects of the alkaloid upon cell viability , dna damage , and nucleus integrity in mouse primary spleen cells and mouse lymphocytic leukemic cells l1210 showed that sanguinarine produces dose - dependent increase in dna damage and cytotoxicity in both cells . in contrast to primary mouse spleen cells , leukemic l1210 cells showed slightly higher sensitivity to sanguinarine , suggesting that cytotoxic and dna damaging effects of sanguinarine are more selective against mouse leukemic cells and primary mouse spleen cells . investigated the possible mechanism through which sanguinarine exerts its antiproliferative action in cultured rat glioblastoma cells and suggested the induction of apoptosis to be due to the downregulation of the extra cellular signal regulated kinase and akt signaling pathway . the effect of sanguinarine on the human cells line hela ( cervix carcinoma cells ) has been studied and the results showed a strong killing effect of sanguinarine which was explained as a consequence of its easy penetration through cell membrane owing to nonpolar pesudobase formation and to a high degree of molecular planarity . primary effusion lymphoma [ pel ] is an incurable , aggressive b - cell malignancy that develops rapid resistance to conventional chemotherapy . it was established that sanguinarine inhibits cell proliferation and induces apoptosis in a dose dependent manner in several pel cell lines and suggested that the alkaloid is a potent inducer of apoptosis of pel cells via upregulation of death receptor 5 and raise the possibility that sanguinarine may be of value in the development of novel therapeutic approaches for the treatment of pel cells . to investigate sanguinarine sensitivity in neuroendocrine tumor cell lines ( human pancreatic carcinoid and human bronchial carcinoid cells ) , larsson et al . reported that these tumor cell lines are very much sensitive to sanguinarine , which may be used , in clinical trials and show therapeutic effect in patients with neuroendocrine tumors . a recent study showed that treatment of human breast cancer mda-231 cells with sanguinarine induced remarkable apoptosis accompanying the generation of reactive oxygen species leading to cell death . very recently matkar et al . studied the effect of sanguinarine in human colon cancer cell - line and showed its ability to cause dna single and double stranded break as well as increased level of 8-oxodeoxyguanosine and reported dna damage consistent with colon cancer cell death . alkaloids of plant origin are natural products that exhibit a myriad of biological and pharmacological properties . in view of their extensive occurrence in nature and significantly low toxicities , prospective development and use of these alkaloids as this review has focused on nucleic acid binding properties and topoisomerase inhibitory activities of some important representatives of the protoberberine ( berberine , palmatine , and coralyne ) and benzophenanthridine ( sanguinarine ) groups of alkaloids and their derivatives in relation to their role in cancer . a large amount of published data suggests that all these alkaloids bind to various polymorphic dna and also to single stranded poly(a ) structures as evidenced from diverse biophysical techniques . berberine and palmatine bind to the b - form dna by partial intercalation . on the other hand , berberine binds to left - handed hoogsteen base paired h - form dna suggesting the effective use of berberine as sensitive probes to detect handedness change in dna on protonation but it does not bind to left - handed watson - crick base paired z - form . coralyne on the other hand exhibits strong binding to duplex b - form dna and single stranded poly(a ) structure by mechanism of intercalation as well as it induces self - structure formation on binding to single stranded poly(a ) . again , berberine and coralyne have the ability to induce and stabilize dna triplexes and g - quadruplex structures ( including human g - quadruplex ) as well . their efficiency in inhibiting telomerase and topoisomerase activity may potentiate their use as potential anticancer drugs . the alkaloid sanguinarine is known for its anticancer / antitumor properties and possesses the potential for selective / preferential elimination of cancer cells . it binds to b - form duplex dna and single stranded poly(a ) structure very strongly by intercalation and it induces the conversion of single stranded poly(a ) to double - stranded poly(a ) on binding . sanguinarine does not bind to z - form or h - form but it converts both z - form and h - form dna to bound b - form structure . it also formed a strong complex with triplex dna that may lead to its use in triplex - targeted cancer therapy . sanguinarine has been shown to stabilized the intramolecular dna g - quadruplex formed in human teleomeric sequence ( tandem d(ttaggg ) repeats ) and to inhibit the activity of telomerase and teleomere maintenance . the striking aspect here is that the specific binding of all these alkaloids to single - stranded adenine regions of the mrna - poly(a ) tail could interfere in mrna processing by human pap to be significantly overexpressed in human cancer cells and may emerge as new type of rna based therapeutic agents for cancer diseases . thus , the differential binding of these alkaloids to various polymorphic nucleic acid conformations with specific biological functions may potentiate their use in nucleic acid - targeted drug design that in turn may convey some specific meaning for their regulatory roles in neoplastic diseases .

bioactive alkaloids occupy an important position in applied chemistry and play an indispensable role in medicinal chemistry . amongst them , isoquinoline alkaloids like berberine , palmatine and coralyne of protoberberine group , sanguinarine of the benzophenanthridine group , and their derivatives represent an important class of molecules for their broad range of clinical and pharmacological utility . in view of their extensive occurrence in various plant species and significantly low toxicities , prospective development and use of these alkaloids as effective anticancer agents are matters of great current interest . this review has focused on the interaction of these alkaloids with polymorphic nucleic acid structures ( b - form , a - form , z - form , hl - form , triple helical form , quadruplex form ) and their topoisomerase inhibitory activity reported by several research groups using various biophysical techniques like spectrophotometry , spectrofluorimetry , thermal melting , circular dichroism , nmr spectroscopy , electrospray ionization mass spectroscopy , viscosity , isothermal titration calorimetry , differential scanning calorimetry , molecular modeling studies , and so forth , to elucidate their mode and mechanism of action for structure - activity relationships . the dna binding of the planar sanguinarine and coralyne are found to be stronger and thermodynamically more favoured compared to the buckled structure of berberine and palmatine and correlate well with the intercalative mechanism of sanguinarine and coralyne and the partial intercalation by berberine and palmatine . nucleic acid binding properties are also interpreted in relation to their anticancer activity .

SECTION 1. SHORT TITLE. This Act may be cited as the ``Flood Insurance Affordability and Risk Notification Act''. SEC. 2. 5-YEAR DELAY IN EFFECTIVE DATE OF MANDATORY PURCHASE REQUIREMENT FOR NEW FLOOD HAZARD AREAS. (a) In General.--Section 102 of the Flood Disaster Protection Act of 1973 (42 U.S.C. 4012a) is amended by adding at the end the following new subsections: ``(i) Delayed Effective Date of Mandatory Purchase Requirement for New Flood Hazard Areas.-- ``(1) In general.--In the case of any area that was not previously designated as an area having special flood hazards and that, pursuant to any issuance, revision, updating, or other change in flood insurance maps that takes effect on or after September 30, 2007, becomes designated as an area having special flood hazards, if each State and local government having jurisdiction over any portion of the geographic area has complied with paragraph (2), such designation shall not take effect for purposes of subsection (a), (b), or (e) of this section, or section 202(a) of this Act, until the expiration of the 5-year period beginning upon the date that such maps, as issued, revised, update, or otherwise changed, become effective. ``(2) Notice requirements.--A State or local government shall be considered to have complied with this paragraph with respect to any geographic area described in paragraph (1) only if the State or local government has in accordance with such standards as shall be established by the Director-- ``(A) developed an evacuation plan to be implemented in the event of flooding in such portion of the geographic area; and ``(B) developed and implemented an outreach and communication plan to advise occupants in such portion of the geographic area of potential flood risks, appropriate evacuation routes under the evacuation plan referred to in subparagraph (A), the opportunity to purchase flood insurance, and the consequences of failure to purchase flood insurance. ``(3) Rule of construction.--Nothing in paragraph (1) may be construed to affect the applicability of a designation of any area as an area having special flood hazards for purposes of the availability of flood insurance coverage, criteria for land management and use, notification of flood hazards, eligibility for mitigation assistance, or any other purpose or provision not specifically referred to in paragraph (1). ``(j) Availability of Preferred Risk Rating Method Premiums.--The preferred risk rate method premium shall be available for flood insurance coverage for properties located in areas referred to in subsection (i)(1) and during the time period referred to in subsection (i)(1).''. (b) Conforming Amendment.--The second sentence of subsection (h) of section 1360 of the National Flood Insurance Act of 1968 (42 U.S.C. 4101(h)) is amended by striking ``Such'' and inserting ``Except for notice regarding a change described in section 102(i)(1) of the Flood Disaster Protection Act of 1973 (42 U.S.C. 4012a(i)(1)), such''. (c) No Refunds.--Nothing in this section or the amendments made by this section may be construed to authorize or require any payment or refund for flood insurance coverage purchased for any property that covered any period during which such coverage is not required for the property pursuant to the applicability of the amendment made by subsection (a). SEC. 3. 5-YEAR PHASE-IN OF FLOOD INSURANCE RATES FOR NEWLY MAPPED AREAS. (a) In General.--Section 1308 of the National Flood Insurance Act of 1968 (42 U.S.C. 4015) is amended-- (1) in subsection (a), in the matter preceding paragraph (1), by inserting ``or notice'' after ``prescribe by regulation''; (2) in subsection (c), by inserting ``and subsection (g)'' before the first comma; and (3) by adding at the end the following new subsection: ``(g) 5-Year Phase-In of Flood Insurance Rates for Newly Mapped Areas.--Notwithstanding any other provision of law relating to chargeable risk premium rates for flood insurance coverage under this title, in the case of any area that was not previously designated as an area having special flood hazards and that, pursuant to any issuance, revision, updating, or other change in flood insurance maps, becomes designated as such an area, during the 5-year period that begins upon the expiration of the period referred to in section 102(i)(1) of the Flood Disaster Protection Act of 1973 with respect to such area, the chargeable premium rate for flood insurance under this title with respect to any property that is located within such area shall be-- ``(1) for the first year of such 5-year period, 20 percent of the chargeable risk premium rate otherwise applicable under this title to the property; ``(2) for the second year of such 5-year period, 40 percent of the chargeable risk premium rate otherwise applicable under this title to the property; ``(3) for the third year of such 5-year period, 60 percent of the chargeable risk premium rate otherwise applicable under this title to the property; ``(4) for the fourth year of such 5-year period, 80 percent of the chargeable risk premium rate otherwise applicable under this title to the property; and ``(5) for the fifth year of such 5-year period, 100 percent of the chargeable risk premium rate otherwise applicable under this title to the property.''. (b) Regulation or Notice.--The Administrator of the Federal Emergency Management Agency shall issue an interim final rule or notice to implement this section and the amendments made by this section as soon as practicable after the date of the enactment of this Act. SEC. 4. COMMUNICATION AND OUTREACH. (a) In General.--The Administrator of the Federal Emergency Management Agency shall-- (1) work to enhance communication and outreach to States, local communities, and property owners about the effects of-- (A) any potential changes or updates to National Flood Insurance Program rate maps that may result under section 1360 of the National Flood Insurance Act of 1968 (42 U.S.C. 4101); and (B) that any such changes or updates may have on flood insurance purchase requirements; (2) engage with local communities to enhance communication and outreach to the residents of such communities on the matters described under subparagraph (A); and (3) on the website of the Federal Emergency Management Agency make publicly available information on-- (A) the various types of flood protection measures applicable to different classes and types of structures that are located in an area having special flood hazards; (B) the property and casualty insurance companies that participate in the National Flood Insurance Program and that write and service standard flood insurance policies; (C) the availability and cost of flood insurance-- (i) under the National Flood Insurance Program; and (ii) in the private marketplace; (D) data related to the structural status of each levee, dam, or other man-made structure designed to provide protection from floods; and (E) how homeowners and communities can mitigate their flood risk. (b) Required Activities.--The communication and outreach activities required under paragraph (1) shall include-- (1) notifying property owners when their properties become included in, or when they are excluded from, an area having special flood hazards and the effect of such inclusion or exclusion on the applicability of the mandatory flood insurance purchase requirement under section 102 of the Flood Disaster Protection Act of 1973 (42 U.S.C. 4012a) to such properties; (2) educating property owners regarding the flood risk and reduction of this risk in their community, including the continued flood risks to areas that are no longer subject to the flood insurance mandatory purchase requirement; (3) educating property owners regarding the benefits and costs of maintaining or acquiring flood insurance, including, where applicable, lower-cost preferred risk policies under the National Flood Insurance Act of 1968 (42 U.S.C. 4011 et seq.) for such properties and the contents of such properties; (4) educating property owners about flood map revisions and the process available to such owners to appeal proposed changes in flood elevations through their community; and (5) encouraging property owners to maintain or acquire flood insurance coverage.

Flood Insurance Affordability and Risk Notification Act - Amends the Flood Disaster Protection Act of 1973 to delay, for a five-year period, the effective date for the mandatory purchase of flood insurance for certain new flood hazard areas not previously designated as having special flood hazards (with "100-year floodplains"). Limits such delay to geographic areas whose state or local governments have developed an evacuation plan and implemented an outreach and communication plan to advise occupants of flood risks and evacuation routes. Makes the preferred risk rate method premium available for flood insurance coverage for properties located in such areas during such five-year time period. Amends the National Flood Insurance Act of 1968 to set forth a five-year phase-in of flood insurance rates for newly mapped areas not previously designated as having special flood hazards. Directs the Administrator of the Federal Emergency Management Agency (FEMA) to: (1) work to enhance communication and outreach to states, local communities, and property owners about the effects of any potential changes or updates to National Flood Insurance Program rate maps, including their effects on flood insurance purchase requirements; (2) engage with local communities to enhance communication and outreach to their residents; and (3) make certain information available to the public on the FEMA website, including information on the availability and cost of flood insurance.

it is known , since long time , that ring - shaped organic molecules , such as benzene or naphthalene , show very large diamagnetic susceptibilities and a very pronounced diamagnetic anisotropy : the diamagnetic susceptibility has normal values in the plane of the aromatic molecules but abnormally large ones in the direction perpendicular to this plane . a first qualitative explanation of this phenomenon as arising from the larmor precession of electrons in orbits including many nuclei can be traced back to p. ehrenfest in 1925 @xcite . this idea was further developed eleven years later by l. pauling who proposed a quasi - classical description of the @xmath0 electronic currents around the rings using an electrical network as a model @xcite . one year latter , in 1937 , f. london set up the `` modern '' theoretical description of this phenomenon by using a tight binding model which included the magnetic field in form of a complex phase of the usual transfer integral @xcite . this is the so - called london ( or peierls ) substitution widely used nowadays . the comparison between the results given by these early theoretical works and the experimental data available at that time is quite satisfactory @xcite . however , the interest for this topic has nearly vanished most probably due to experimental limitations . for instance , in the theory of london , the electronic spectrum of aromatic molecules is a periodic function of the magnetic flux with a period equal to a flux quantum @xmath1 . but the value of the magnetic field needed to cover a full period is of order @xmath2 t for the materials existing until few years ago . such huge values can not be reached experimentally , and are due to the extremely small perimeter , of order a few tens of angstrms , of the materials studied previously . today , material science has made considerable progress and many new carbon materials with nanoscopic characteristic length exist . an example is given by multi - walled carbon nanotubes with a diameter of approximately 10 nm @xcite . for these new materials , the magnetic field needed to reach a flux quantum is about a few tens of tesla only and the periodicity mentioned before can be observed @xcite . on the other hand , during the last years considerable progress has been made in precise measurements of the real part of the low - frequency dielectric function @xmath3 . in particular these experiments have been extended to ultra - low temperatures . ratios of @xmath4 up to @xmath5 were achieved in the mk temperature regime . a rather spectacular success associated with that progress was the observation of a strong magnetic - field dependence of the polarisability of multicomponent glasses @xcite . these developments suggest reconsideration of the magnetic field effects in organic nanostructures such as large aromatic molecules or carbon nanotubes for instance . in particular , the magnetic field should have a very pronounced effect on the polarisability of these organic systems which should be observable nowadays @xcite . these measurements could then be used as a new spectroscopic tool to obtain informations on the electronic properties of organic materials . the aim of this paper is to review various theoretical works developed in dresden during the last two years in that direction @xcite . similar ideas were already pointed out recently for quite different materials and purposes . indeed , in @xcite small particles ( rings , disks or spheres ) were considered in connection with weak localisation . in particular , it was found that the polarisability should be greater in an applied magnetic field than in zero field because a field partially suppresses weak localisation . this theoretical prediction was observed very recently in the ac polarisability of mesoscopic rings @xcite . although the studies already done until now on the behaviours of the dielectric susceptibility of cylindrical organic materials under magnetic field @xcite should be improved in several ways by including , e.g. , explicitely coulomb interactions , we believe the phenomena pointed out here are robust in the sense that they will survive a more sophisticated theoretical treatments . therefore , we think that the polarisability in a magnetic field could be a useful quantity to study experimentally in order to obtain insight into the electronic structure of carbon made materials . in our opinion , this justify the topic of this review and , we hope that it will help to motivate new experiments . the series of works described here is related to the studies of persistent currents in metallic rings . before starting , we would like to mention recent review articles on this topic . interested readers could refer to ref . @xcite for the case of diffusive electron motion and to ref . @xcite for ballistic electron motion . the review is organised as follows . in section 2 we describe the aharonov - bohm effect in cylindrical nanostructures by using london s substitution . in section 3 and 4 , we point out dramatic consequences of this effect on the dielectric function of nanoscopic organic cylinders such as carbon nanotubes ( section 3 ) , and a finite plane of graphite where the edge states existing in these materials define effective rings ( section 4 ) . finally , before concluding , we point out a few properties of strongly interacting electrons on rings and cylinders in an applied field . in this paper , we are interested in the effects of an applied magnetic field on the orbital degrees of freedom only . therefore we consider spinless fermions except in the last section . the zeeman interaction was briefly discussed in @xcite . in the range of field strength we are interested in , the diamagnetic response is the most important one . let us first consider a ring of @xmath6 sites pierced by an axial magnetic field . the hamiltonian , making use of the london substitution @xcite , is the following @xmath7 where @xmath8 , ( @xmath9 ) are spinless fermion creation ( annihilation ) operators and @xmath10 is the magnetic flux through the ring in units of the flux quantum @xmath11 ( @xmath1 ) . it is proportional to the area enclosed by the ring @xmath12 where @xmath13 is the lattice constant . for a ring with a few hundred sites and assuming @xmath14 , the magnetic field needed to reach @xmath15 is not more than a few tens tesla - values reachable experimentally . introducing the wave function @xmath16 , where @xmath17 are the @xmath0 orbitals located at sites @xmath18 , one obtains the following eigenvalue equations with periodic boundary conditions @xmath19where @xmath20 is the eigenvalue . by performing a pseudo - gauge transformation introduced by bayers and yang @xcite , @xmath21 , eqs . ( [ eigenring ] ) can be written in the form @xmath22 the effect of the magnetic field appears in the new periodic boundary conditions . an analysis of them shows that the spectrum of the system is a periodic function of @xmath10 with period 1 , as already mentioned in the introduction . this is an important information since it implies that every thermodynamic quantity is also periodic function of @xmath10 with the same period . moreover , the system is invariant with respect to the transformation @xmath23 . therefore its spectrum - and every thermodynamic quantity - is symmetric with respect to @xmath24 . in principle , it is then necessary to study the system only for @xmath25 $ ] . the eigenvalues for the ring are @xmath26with @xmath27 . using this expression one notices crossing between levels occurring at special values of @xmath10 , namely @xmath28 and @xmath29 ( for an example see fig . 1 ) . let us now consider cylinders made by rolled square lattices with an applied axial magnetic field ( fig . the hamiltonian for spinless fermions is @xmath30where the magnetic flux is still given by expression ( [ flux ] ) . the resulting eigenvalues are @xmath31 with @xmath32 and @xmath33 . we have applied open boundary conditions at the ends of the cylinder . the resulting one - electron wave functions are @xmath34 where @xmath35 is the vacuum . again , using the expression ( [ spectrum ] ) , one notices many level crossings induced by the magnetic field ( fig . 3 ) . compared to the results obtained for rings , the important difference is that the crossings appear for values of @xmath10 depending on the geometry of the system @xmath36 ; in particular , they appear for other values than @xmath37 , @xmath38 and @xmath29 . due to their intricate patterns , numerous changes of the ground state induced by the magnetic field do occur . as an example , we show in figure 4 as function of the magnetic flux the energies of the ground state and the first excited state of a cylinder with @xmath39 , @xmath40 and with @xmath41 electrons in it . the number of crossing points and the values of @xmath10 for which they occur depend crucially on the geometry of the system as we have already mentioned above but , also , on the electron filling . we will not attempt to explain the crossing point pattern here . instead , as shown in the next section , we want to point out that the changes of the ground state associated with the crossing points , have strong influences on the static polarisability . therefore this quantity could be used as a new spectroscopic tool to obtain informations on excited states or on the system geometry for instance . carbon nanotubes form a class of cylindrical systems of growing importance nowadays @xcite . the calculations above can be straightforwardly extended to those systems , in particular for achiral nanotubes , i.e. the armchair and zig - zag nanotubes considered here @xcite . for these particular systems with a uniform magnetic field along their axis , we find by using again a nearest - neighbours tight binding model , the following spectrum @xcite @xmath42 where for zig - zag nanotubes @xmath43and for armchair nanotubes @xmath44the roles of @xmath45 and @xmath46 are just exchanged from one case to the other . using the expressions ( [ spectrumnano]-[armchair ] ) , one notices that - as for the case of rolled square lattices - the ground state of rolled honeycomb lattices changes also strongly in a magnetic field . therefore , as for the case of rolled - square lattices , the static electric polarisability of carbon nanotubes are also expected to be strongly influenced by an axial magnetic field @xcite . it is the purpose of the next section to analyse the structure of the dielectric susceptibility of cylindrical organic nanostructures in presence of an applied magnetic field . moreover , the electronic spectrum of carbon nanotubes is also a periodic function of the magnetic flux , a behaviour which has been confirmed experimentally in @xcite . very precise measurements of the polarisability can be done nowadays . two recent examples are given in @xcite for multicomponent glasses and in @xcite for mesoscopic metallic rings . the complicated electronic spectrum of cylindrical organic nanostructures - including carbon nanotubes - induced by an axial magnetic field causes important effects in the polarisability of these systems as we want to discuss in the following . for simplicity let us focus on rolled square lattices only . we give one example for carbon nanotubes in this section but , more informations can be found in @xcite . with a uniform dc electric field @xmath47 , the tight binding model becomes @xmath48where @xmath49 is the dipole operator . in the following , two different orientations for the electric - field are considered . the corresponding expression for the dipole operator are @xmath50 for longitudinal field , where @xmath13 is the lattice spacing and @xmath51 is the total length of the tube , and @xmath52 for transversal field , where @xmath53 is the radius of the cylinder ( fig . the first case was studied in @xcite , the second in @xcite . we are interested in the behaviour of the induced dipole moment as function of the magnetic flux @xmath54where , as usual , @xmath55 and @xmath56 is the chemical potential which is a function of the magnetic field . we summarise in the following , the main results of the studies done in @xcite . in this case , the hamiltonian of the system is given by eqs . ( [ tbe ] ) and ( [ dipoleoperatorl ] ) . with this model it becomes tedious to evaluate the polarisability ( [ dipole ] ) , for long chains . instead of doing exact calculations we proceed by using a semi - classical approximation very powerful in this specific context @xcite . we are interested in the linear regime where the potential induced by the electric field , @xmath57 , is slowly varying on the scale of the fermi wave length . then , the thomas - fermi approximation may be applied @xcite . we assume that it is meaningful to consider an energy depending on the position , @xmath58 , on the chain @xmath59 where @xmath60 is given by the expression ( [ spectrum ] ) . next , within this semi - classical approximation , the polarisability is evaluated as follows . @xmath61 at this stage , it should be noticed that the interaction which leads to an energy splitting at crossing points when the electric field is turned on , is neglected here . therefore , a possible first order stark effect near those points is not taken into account with this approximation . to illustrate the relevance of this approximation , we consider first a linear chain in the absence of a magnetic field . in this case , the quasi - classical energy at position @xmath58 is given by @xmath62 and the corresponding polarisability by @xmath63 figure 5 shows an example for a linear chain with 201 sites . the exact polarisability is compared with the semi - classical one ( eq . [ tfchain ] ) as function of the electron filling for two different values of the temperature . one can see that the deviations caused by the semi - classical approximation are less than @xmath64 or @xmath65 . this justifies the use of this approximation for cylindrical systems in a magnetic field . figure 6 shows the results for a cylinder with @xmath66 sites along the circumference and @xmath67 sites along the cylindrical axis . the temperature is @xmath68 in units of @xmath69 ( around 1k ) and the density is 0.74 electrons per site . since the polarisability is symmetric with respect to the point @xmath70 , as mentioned before , only the regime @xmath71 is shown . obviously there is a huge effect of the magnetic field on the polarisability . these conclusions are based on a semi - classical approximation . in the next subsection we present full quantum calculations for the case where the electric field is perpendicular to the cylindrical axis . therefore , we postpone a complete discussion of the results to the next subsection where they do not suffer from any approximation in the context of our simplified model . the hamiltonian describing the system is now given by eqs . ( [ tbe ] ) and ( [ dipoleoperatort ] ) . the advantage of this choice is to allow for a separation of variable : the motion of the electrons along the circumference and the cylindrical axis can be treated separately . exact calculations can be done even for very long cylinders . proceeding that way , the problem is reduced to a study of one - dimensional rings in applied electric and magnetic fields @xcite . we show in fig . 7b the magnetic field dependence of the polarisability for a cylinder with @xmath72 and @xmath40 and very few electrons on it , @xmath73 ( this corresponds to a band filling of only @xmath74 ) . in this example , the electric field is such that @xmath75 ( linear regime ) and the temperature is @xmath76 ( @xmath77 ) . we choose this example because it shows very clearly the main behaviours of the dielectric response . in particular we choose @xmath72 because this gives an illustration of the signature of the linear stark effect . together with this example the energies of the ground state and first excited state are shown without electric field as function of the magnetic flux ( fig . first of all the induced dipole moment as function of the magnetic field is periodic with a period of @xmath29 and is symmetric with respect to @xmath38 ; these symmetries are already apparent in the spectrum ( [ spectrum ] ) . second , the induced dipole moment shows clearly two main characteristics : ( i ) we can notice the presence of small peaks at @xmath78 , ( ii ) the induced dipole moment is a discontinuous function showing several jumps separating plateau - like sections . note that there is a slight curvature in the whole spectrum , which is related to the persistent current induced by the magnetic field . as noticed before , a magnetic field induces crossing between the energies of the ground state and the first excited state ( figure 4 and 7a ) . as it can be seen in figures 7 , there is a one to one correspondence between level crossing at zero electric field and each kink in the induced dipole moment . at each crossing , the ground state of the system changes . these two states which are crossing respond differently to an applied electric field . both produce a quadratic stark effect but generally of different size . this explains why the induced dipole moment is not a continuous function of the magnetic field . near the crossing points , the response of the system will depend on whether or not there is a nonzero matrix element of the electric field between the two states involved . if the matrix element vanishes , the picture described above is valid . on the contrary , if there is an interaction between those states , due to the degeneracy , the response will result in a linear ( instead of quadratic ) stark effect with peaks of the induced dipole moment . more precisely , using the expression of the wave function ( [ wavefunction ] ) , the matrix elements of the dipole operator are calculated as @xmath79 with this equation , it is easy to see that a linear stark effect can occur only for a magnetic flux of @xmath80 . these are precisely the values for which one obtains peaks in our first example ( fig . it is worth noticing that large enough coulomb interactions can change drastically the selection rules ( [ selectionrules ] ) . the same is true for distortions of a cylinder as it was shown in @xcite for elliptical cylinders . appearance of a linear stark effect for different values of the magnetic flux could then give a way to quantify importance of electronic correlation effects or to characterise the geometry of the systems under consideration . at low enough temperature , one deals essentially with the spectroscopy of a few levels around the fermi level . therefore it is not surprising that the induced dipole moment for a system which is well ordered , well oriented and of well defined size ( @xmath81 ) , depends strongly on the electronic density . this is clearly seen from figs . 8a and 8b . they are for the very same system considered before but for three different electron fillings @xmath82 and @xmath83 . at such a low density , the relevant mean level spacing , @xmath84 , behaves like @xmath85 . figure 8a is for a temperature lower by one order of magnitude than @xmath84 , while fig . 8b is for a temperature higher by one order of magnitude than @xmath84 . with a typical value for @xmath69 ( @xmath86 ) one can estimate a temperature of @xmath87 for the spectrum 8a and @xmath88 for the spectrum 8b . with these figures we want to emphasise the unique sensitivity of the proposed measurements and also that it is the necessary to work at very small temperatures in order to extract maximum informations . the last examples in fig . 9 is an illustration showing that the same kind of behaviour is expected in carbon nanotubes . it is for armchair ( fig . 9a ) and zig - zag ( fig . 9b ) nanotubes , when both are @xmath74 away from half - filling and at @xmath89 @xcite . today it is possible to measure accurately very small variations in the real part of the dielectric function @xcite . therefore , the dramatic magnetic field effects on the static polarisability of mesoscopic cylindrical systems , discussed here , could be measured and analysed . several important informations about excited states could then be obtained . first , the positions of the discontinuities and peaks should give informations about the energies of the excited states . the nature of the response - linear or quadratic stark effect could be detected and therefore should give informations about the symmetry of the excited states . the magnitude of the response should also give informations about the coupling constants . finally , the different curvatures observed in the whole spectrum could give informations related to the persistent current - or ring current - induced by the magnetic field . until now we were discussing cylindrical systems , such as carbon nanotubes , with a diameter in the mesoscopic range . the diamagnetic current induced by the applied magnetic field is a ring current in a strict geometrical sense . in the following , we will discussed quite different systems closer to those discussed by ehrenfest , pauling and london @xcite . indeed , we consider finite graphene planes where the magnetic field induces a ring current running along the perimeter of these systems . it is very close to the earlier studies where ring currents in benzene or naphthalene molecules were considered . the mesoscopic graphene sheets are new materials of importance for which the magneto - polarisability @xcite could give very useful informations . very recently a new type of magnetism similar to a spin glass state was found for activated carbon fibres prepared at heating temperature over 120023 c @xcite . these materials are supposed to be well described by disordered networks of nanographite layers with a characteristic length of some tens of angstms @xcite . it is worth noting that further increase of the heating temperature will drive the system towards complete graphitisation . on the other hand , recent theoretical works on graphite ribbons have shown the existence of edge states whose wave functions are localised in the near vicinity of the edges of the ribbons and whose energies form a band with a small dispersion centred in the middle of the gap @xcite . therefore , these states can have important physical consequences since they make a relatively large contribution to the density of state at the fermi level . for instance , they are expected to affect novel electrical and magnetic properties such as a paramagnetic behaviour at low temperature @xcite . in the light of these theoretical works , it was suggested by shibayama et al . that the edge states should be responsible for the spins observed in @xcite . the spin glass behaviours could then be explained by invoking heisenberg like interactions between these effective spins since the disordered network of nanographite layers gives rise to a random exchange interaction network . in this context , we want to stress in this section that measurements of the magneto - polarisability may be a very direct and efficient way to detect possible edge - states in activated carbon fibres or any other amorphous carbon material . this new way of probing electronic structure of carbon materials could help to support the hypothesis made in @xcite . moreover , we believe that this quantity could give a way to access characteristic length of graphitic regions in such compounds - quantity studied today using raman spectroscopy @xcite . for that purpose , we consider first rectangular finite planes of graphite ( fig . these simplest systems show two different kinds of edges : zig - zag and armchair edges . the one - band @xmath0 electrons are again described by a nearest - neighbours tight binding hamiltonian defined on the topologically equivalent brick - type lattice already used in @xcite , @xmath90 where the summation is over nearest - neighbour sites located at @xmath91 coordinates , @xmath92 and @xmath93 . as found in references @xcite , our studies of ( [ tbgraphene ] ) show the existence of edge states for finite rectangles of graphite . moreover , in agreement with the results of @xcite for ribbons , the wave functions of the edge states are shown to be localised preferentially on the zig - zag edges . in particular the weight of these functions is negligible on the armchair edges . this remark could be of importance for real materials leading to the question about the stability of such states in layers with disordered shape . we postpone a discussion of this important question to a future publication . finally , the energies of these states are near the middle of the gap ; the closer it is to the middle , the more localised on the edges is the corresponding wave function . next we apply a uniform magnetic field @xmath94 perpendicular to the layer . in the tight binding model we then proceed once more by using the london substitution @xcite , @xmath95 , where @xmath96 is the vector potential . we write @xmath97where @xmath98 and @xmath99 are the appropriate line integral of the vector potential . since the magnetic field is uniform , one must have ( cf fig . 10 ) , again in units of @xmath11 @xmath100 for calculations we choose , as in @xcite , the landau gauge . @xmath101 it should be noticed that the elementary magnetic flux is defined here with respect to the size of a unit cell , namely a benzene ring , which requires an extremely large field except for the edge states where the relevant unit is given by the size of the whole layer - corresponding to a much more reasonable magnetic field of some tens tesla . in that sense , the edge - states define an effective rings . the idea is quite simple : only the edge states will react to small values of an applied magnetic field such that the corresponding characteristic length of the cyclotron radius is of the same order than the size of the layer . subsequently , the signature of the edge states should be seen in the polarisability as function of magnetic field . we then add a static uniform electric field in the plane of the layer and calculate the magneto - polarisability for different electron - fillings . in this case , the dipole operator takes the following general expression @xmath102 where the site vector @xmath103 is defined with respect to an arbitrary origin . we choose a system with a total of 76 benzene rings with 10 along the zig - zag edges . we work at small temperature @xmath104 which could be estimated to @xmath89 . the particular example studied here shows only two nearly degenerate edge states at zero energy . the edge states will be populated at half - filling but since the temperature is low compared to the energy gap , they are not occupied if one reduces the electron number by one . figure ( 11 ) shows the magneto polarisability for these two cases . we see very clearly a quadratic dependence of the polarisability as function of the magnetic field for the half - filled case only . for the other case , no sensible effect are seen . we can then conclude that the edge states are responsible for this quadratic behaviour in accordance with the argument given above . to conclude this section , it should be stressed that the relative variations of the polarisability in fig . 11 for the case with occupied edge states can be detected nowadays . therefore , we believe it is possible to identify the existence of edge states in activated carbon fibres , or other amorphous carbon materials , using measurements of the magneto - polarisability . moreover , we believe that a careful analysis of the quadratic behaviour shown in fig . 11 can help to gain important informations about these disordered materials such as the effective sizes of the graphite - like regions for instance . so far we did nt consider coulomb interactions . instead , we were assuming that they were included in the effective one - electron parameters of our tight - binding models . however , for quantitative results of the polarisation , it is needed to include explicitely those interactions . it is well known that the absolute value of the polarisation of organic compounds decreases strongly by including interaction corrections @xcite . we will not attempt such studies here which will be the subject of a subsequent publication . instead , we will consider several strongly interacting systems , rings or small cylinders , in the extreme limit of infinite on - site interactions , our purpose being to point out that coulomb interactions can produce not only quantitative changes but , also , important qualitative changes in the behaviour of the polarisability . in the early nineties , several authors have studied the behaviour of persistent currents in mesoscopic hubbard rings threaded by a magnetic field @xcite . one of the most prominent result of these studies was obtained in the limit of infinite interaction , @xmath105 . in this limit , kusmartsev pointed out that , in the case of spin @xmath38 fermions , the persistent current has a surprising short period given by @xmath106 ( in unit of @xmath11 ) , where @xmath107 is the number of electrons @xcite . he called this intriguing new phenomena , fractional aharonov - bohm effect . it is this result which we shortly describe here . the tight binding hubbard model for a ring with @xmath6 sites is of the form @xmath108 where @xmath109 is the usual electron number operator . the magnetic flux @xmath10 is given by the expression ( [ flux ] ) . an advantage of the hubbard ring is to be one of the strongly - correlated - electron system that is solvable by using the bethe ansatz @xcite . in the presence of a magnetic field the form of the wave function does nt change @xmath110\exp(i\sum_{j=1}^{n_e}k_{p_j}x_{q_j})\ ] ] where @xmath111 and @xmath112 are two permutations of @xmath113 . the coefficients @xmath114 $ ] as well as @xmath115 are determined from bethe s equations which in a magnetic field are modified by the addition of the flux phase @xmath10 @xcite . @xmath116 @xmath117@xmath107 is the number of charges i.e. the number of electrons , and @xmath118 is the number of down - spins . the eigenstates of a ring are characterised by the momenta @xmath119 of the charges and the rapidities @xmath120 of spin waves . the energy of the system is given by @xmath121 in the limit of infinite interaction @xmath105 bethe s equations are greatly simplified to give the following results @xmath122 where the quantum numbers @xmath123 and @xmath124 are connected with charge and spin degrees of freedom respectively . they are either integers or half odd integers , depending on the parities of the numbers of down- and up - spin electrons : @xmath125 the equation ( [ uinfinity ] ) is identical to the one describing a set of non - interacting spinless fermions on a ring threaded by a flux @xmath126 . the second term of this expression is the effective magnetic flux created by the spin excitations . it comes from the fact that there is an additional phase shift between the momenta of the different electrons due to the repulsive interaction . because of this shift , the periodicity of the aharonov - bohm flux takes a fractional value at the infinite interaction limit . it is easy to check this statement by using eqs . ( [ energybethe ] ) and ( [ uinfinity ] ) and by appropriately choosing the quantum numbers ( [ quantumnumbers ] ) in order to minimise the energy of the system . one example is shown in fig . 12a for a ring with 8 sites and 2 electrons , one up and one down . another example is shown in fig . 12b for the very same ring but for 5 electrons , 3 up and 2 down . the fractional aharonov - bohm effect is clearly seen in these examples . it is important to stress once more that the spin plays an essential role in this phenomena . this can be seen in ( [ uinfinity ] ) where the quantum numbers associated to the spin degree of freedom appear as responsible of the fractional ab effect . without this term we recover the known result for free fermion rings ( [ eigenvaluering ] ) . in particular , for spinless fermions , the periodicity with the flux is 1 . in the case of infinite interaction or spinless fermions , we can use the following argument to obtain the correct flux periodicity and which stresses the important role played by the spin . let us take a particular configuration with @xmath127 electrons , @xmath128 . one may ask the question of how many hops of the particles in the same direction should take place in order to recover the starting configuration . in mathematical terms we may write @xmath129 where @xmath130 is a phase term cause by the pauli s principle . @xmath131 are general coordinates of the electron @xmath132 taking account of the spin when necessary . @xmath133 are the operator of translation by one site in the clockwise direction ( for instance ) of the electron @xmath132 . @xmath134 is the number of one - site - hopping of the particle @xmath132 . the answer to this question depends on whether or not we consider the spin degree of freedom . in the cases we are interested in , the fermions are locked together and form a kind of dynamical wigner crystal . by moving on the lattice , an electron will push the others in the same direction . for the case of spinless fermions , since all particles are indistinguishable , it is easy to see that @xmath135 to get back to the initial configuration . the same is true for an assembly of free spin @xmath38 fermions . on the other hand , one come back to the same configuration by interchanging the particles which , due to the pauli s principle , give the following statistical flux : @xmath136 . the immediate conclusions are , first , that the periodicity of the energy with the flux will be 1 ( as for the free electron case ) and , second , there will be a parity effect which discriminates between the cases with even and odd number of particles . indeed , it was shown by kusmartsev @xcite ( and references therein ) , that a system of interacting spinless fermions on a ring behaves as a paramagnet for even number of particles and as a diamagnet for an odd number of particles . this property is sometimes known as _ leggett s conjecture _ @xcite . for the case of spin @xmath38 fermions , the conclusions are completely different . indeed , one easily sees that @xmath137 and @xmath138 . each particle should go round the ring and therefore , the statistical flux is just unity . consequently , the effective charge of the system will be @xmath139 and the periodicity of the energy will be @xmath140 - this is the fractional aharonov - bohm effect discovered by kusmartsev @xcite . moreover , there is no parity effect : indeed , it is known that the system is always diamagnetic for infinite interactions @xcite . on the basis of these analysis , let us now consider strongly - interacting cylindrical systems in some limiting cases where conclusions could be reach following the same argumentation . let us first consider a stack of isolated rings with only one electron per ring . the rings are interacting following the model @xmath141 where there is a nearest - neighbour interaction between two electrons when they are on top of each other . this hamiltonian could help to describe stack of large aromatic molecules with only one electron in each in the lumo . it could also be an effective model to describe interacting edge - states in stack of finite graphene planes . this model was already used in @xcite in the continuum limit , where an interesting new parity effect was pointed out to occur in the dielectric response of one - dimensional stack of quantum rings . here , we are only interested by the periodicity of the ground state energy with the magnetic flux in the limit of infinite interaction . once again , starting from one particular electronic configuration , we are asking the same question about the number of particle hopping in the same direction one should do to come back to it . it is then possible to write down a similar expression than ( [ periodicity ] ) with @xmath137 and @xmath138 where @xmath127 is the number of rings and @xmath6 , the number of sites in each ring . consequently , one can conclude that the periodicity is @xmath140 and that there is no parity effect . the label of the ring acts as a spin degree of freedom . it is worth mentioning that it exists a rigorous mathematical proof of these properties @xcite . last , we are considering a model of interacting cylinders @xmath142 with again @xmath143 . again we are asking the same question about the periodicity formulating it in terms of equation ( [ periodicity ] ) . one has to distinguish between the case of spin @xmath38 and spinless fermions . * for spinless fermions , for a non vanishing @xmath144 , one has @xmath135 and @xmath138 ; the periodicity is one and there is no parity effect . * for spin @xmath38 fermions , whatever is the value of @xmath144 , one has @xmath137 and @xmath138 ; the periodicity is @xmath140 and there is no parity effect . in conclusion , there is an abrupt transition from a fractional aharonov - bohm state to an usual aharonov - bohm state going from @xmath145 to @xmath146 in the case of spinless fermions ; on the contrary , there is no such transition for spin @xmath38 fermions . the main purpose of this review is to point out the strong magnetic field dependence of the static polarisability of nanoscopic cylindrical organic materials when the magnetic field is parallel to the tube axis . this was done by studying two kinds of system . on one hand we have considered real cylinders in the form of rolled square lattices but also , rolled honeycomb lattices , more specifically , achiral carbon nanotubes . they were studied with both , semiclassical approximation @xcite and exact diagonalisation @xcite . for all these cases , the polarisability was shown to present very complex structures as function of the magnetic field in which one can identify two different characteristics ( cf fig . 7 ) : ( i ) the polarisability is a non - continuous function with sudden jumps separating plateau - like regions ( ii ) additionally , small peaks may appear for special values of the magnetic field in place of jumps . a full understanding of these complicated behaviours was given by following the behaviour of the ground state by increasing the magnetic field : due to the aharonov - bohm effect , many changes of ground state occur and for some values of the magnetic field accidental degeneracies happen where the ground state becomes two fold degenerate . a one to one correspondence is found between the accidents in the polarisability and the accidental degeneracies of the ground state . each plateau - like region of the polarisability corresponds to a quadratic stark effect with a coefficient proper to the corresponding magnetic - field induced ground state . each peak corresponds to a linear stark effect appearing at accidental degeneracies when there is direct coupling between the two states involved ( cf fig . on the other hand we have studied finite plane of graphene which support edge states . the wave functions of these states have the peculiarity to be mostly localised on the perimeter of the plane defining kind of effective rings . the presence of these states in real materials is a important question since they are able to influence new physical properties @xcite and , we have shown that it is possible to use measurements of the static polarisability in an applied perpendicular magnetic field to detect possible edge states in amorphous carbon materials such as carbon fibres . moreover we believe that a careful analysis of the quadratic behaviour we have pointed out in section iv ( fig . 11 ) , should give a way to determine the characteristic length of the graphitic region in these disordered systems . in a last part of this review , we have briefly described results of some strongly interacting models in the limit of infinite interactions . the main purpose of this section was to pointed out that the interaction can result in new phenomena such as the fractional aharonov - bohm effect which appears for hubbard rings with spin @xmath38 fermions but also in stacks of uncouple rings with one electron per ring . an explicit treatment of the electron - electron interactions is therefore needed and , this is now our main direction of investigation . p. ehrenfest , physica * 5 * , 388 ( 1925 ) ; z. phys . * 58 * , 719 ( 1929 ) . l. pauling , j. chem . * 4 * , 673 ( 1936 ) . f. london , j. phys . radium * 8 * , 397 ( 1937 ) . dresselhaus , g. dresselhaus and p. eklund , `` science of fullerenes and carbon nanotubes '' , academic press ( 1996 ) . a. bachtold , c. strunk , j.p . salvetat , j.m . bonard , l. forro , t. nussbaumer and c. schnenberger , nature 397 , 673 ( 1999 ) . p. strehlow , c. enss and s. hunklinger , phys . lett . * 80 * , 5361 ( 1998 ) ; p. strehlow , m. wohlfahrt , a.g.m . jansen , r. haueisen , g. weiss , c. ens and s. hunklinger , phys . lett . * 84 * , 1938 ( 2000 ) . p. fulde and a.a . ovchinnikov , eur . j. * b 17 * , 623 ( 2000 ) . s. pleutin and a.a . ovchinnikov , eur . j. * b 23 * , 521 ( 2001 ) . s. pleutin and a.a . ovchinnikov , carbon * 40 * , 129 ( 2002 ) . k.h . ahn and p. fulde , phys . rev . * b 62 * , r4813 ( 2000 ) . efetov , phys . rev . lett . * 76 * , 1908 ( 1996 ) . y. noat , b. reulet and h. bouchiat , europhys . lett . * 36 * , 701 ( 1996 ) . m. blanter and a.d . mirlin , phys . b 57 * , 4566 ( 1998 ) . r. deblock , y. noat , h. bouchiat , b. reulet and d. mailly , phys . lett . * 84 * , 5379 ( 2000 ) . u. eckern and p. schwab , j. low . temp . phys . * 126 * , 1291 ( 2002 ) . k. richter , d. ullmo and r.a . jalabert , phys . rep . * 276 * , 1 ( 1996 ) . n. bayers and c.n yang , phys . lett . * 46 * , 7 ( 1961 ) . r. saito , g. dresselhaus and m.s . dresselhaus , `` physical properties of carbon nanotubes '' , imperial college press ( 1998 ) n.w . ashcroft and n.d . mermin , _ solid state physics _ ( saunders college publishing , new york , 1976 ) . y. shibayama , h. sato , t. enoki and m. endo , phys . * 84 * , 1744 ( 2000 ) . m. fujita , k. wakabayashi , k. nakada and k. kusakabe , j. phys . . jpn . * 65 * , 1920 ( 1996 ) . k. wakabayashi , m. fujita , h. ajiki and m. sigrist , phys . b 59 * 8271 ( 1999 ) . a.c . ferrari and j. robertson , phys . rev . * b 61 * , 14095 ( 2000 ) . benedict , s.g . louie and m.l . cohen , phys . rev . * b 52 * , 8541 ( 1995 ) . kusmartsev , j. phys . condens . matter * 3 * , 3199 ( 1991 ) . b.s shastry and b. sutherland , phys . lett . * 65 * , 243 ( 1990 ) ; a.a . zvyagin , fiz . nizk . temp . * 16 * , 1299 ( 1990 ) [ sov . j. low * 16 * , 745 ( 1990 ) ] ; n. yu and m. fowler , phys . rev . * b 45 * , 11 795 ( 1992 ) . lieb and f.y . wu , phys . * 20 * , 1445 ( 1968 ) . leggett , in _ granular nanoelectronics _ , edited by d.k . ferry et al . 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we review recent results on the behaviour of the dielectric function of cylindrical nano - organic materials at very low frequencies in a magnetic field . for cylindrical structures - such as carbon nanotubes - the polarisability is shown to be a discontinuous function of a longitudinal magnetic field where plateau - like regions are separated by sudden jumps or peaks . a relation is pointed out between each discontinuity in the polarisability and the cross - over between ground and first excited states induced by the magnetic field . this one to one correspondence suggests to use measurements of the dielectric function in an applied magnetic field in order to obtain informations about the electronic structures of cylindrical nanostructures . in addition , it is shown , by studying finite graphene layers , that the measurement of the polarisability in a magnetic field could be a powerful way for detecting possible edge - states in amorphous carbon materials such as activated carbon fibres . finally , the importance of the electron - electron interaction is emphasised by discussing examples of strongly interacting electrons on rings or cylinders , in the limit of infinite interaction .

SECTION 1. SHORT TITLE. This Act may be cited as the ``Former Bennett Freeze Area Development Act''. SEC. 2. DEFINITIONS. In this Act: (1) ONHIR.--The term ``ONHIR'' means the Office of Navajo and Hopi Indian Relocation. (2) Secretary.--The term ``Secretary'' means the Secretary of the Interior. (3) Trust fund.--The term ``Trust Fund'' means the Former Bennett Freeze Area Rehabilitation Trust Fund established under this Act. SEC. 3. ONHIR TRANSITION. (a) Request by Tribe; Authorized Programs.--Upon the request of the Navajo Nation or the Hopi Tribe by tribal resolution, the Commissioner of the Office of Navajo and Hopi Indian Relocation shall enter into a self-determination contract or contracts with the requesting Indian tribe to plan, conduct, and administer programs, functions, services, or activities (or portion thereof), including construction programs administered by the Commissioner that pertain directly to the requesting Indian tribe. Programs, functions, services, or activities contracted under this subsection shall include administrative functions of the Office of Navajo and Hopi Indian Relocation that support the delivery of services to Indians, including those administrative activities supportive of, but not included as part of, the service delivery programs described in this subsection that are otherwise contractable. Such administrative functions shall be contractable without regard to the organizational level within the Office of Navajo and Hopi Indian Relocation that carries out such functions. (b) Regulations.--The Commissioner shall issue regulations implementing subsection (a) that, to the maximum extent feasible-- (1) parallel the requirements of the Indian Self- Determination and Education Assistance Act (25 U.S.C. 450f); and (2) reflect the independent agency status of the Office of Navajo and Hopi Indian Relocation. SEC. 4. FORMER BENNETT FREEZE AREA REHABILITATION TRUST FUND. (a) Establishment.--There is hereby established in the Treasury of the United States a trust fund to be known as the Former Bennett Freeze Area Rehabilitation Trust Fund, which shall consist of the funds appropriated pursuant to subsection (f) of this section and any interest or investment income accrued on such funds. (b) Secretary as Trustee; Investment of Funds.--The Secretary shall be the trustee of the Former Bennett Freeze Area Rehabilitation Trust Fund and shall be responsible for investment of the funds in such Trust Fund. Notwithstanding the foregoing, upon receipt and approval of a plan for the use of those funds consistent with subsection (c), the Secretary shall transfer these funds to the Navajo-Hopi Land Commission Office of the Navajo Nation, or its designee, as trustee. (c) Availability of Funds; Purposes.--Funds in the Former Bennett Freeze Area Rehabilitation Trust Fund, including any interest or investment accruing thereon, shall be available to the Navajo Nation solely for purposes which will contribute to the continuing rehabilitation and improvement of the economic, housing, infrastructure, health, educational, and social condition of families, and Navajo communities, that have been affected by the former Bennett Freeze. (d) Deposits to Trust Fund.--The Trust Fund shall consist of-- (1) a set-aside each fiscal year of 0.75 percent of any amounts appropriated for the Operation of Indian Programs budget of the Bureau of Indian Affairs; (2) a set-aside each fiscal year of 5.0 percent of any amounts appropriated for the Indian Housing Block Grant Program under title I of the Native American Housing and Self- Determination Act of 1996; (3) a set-aside each fiscal year of 0.75 percent of any amounts appropriated for the Rural Development Program (title III); and (4) any amounts appropriated, transferred, or credited to the Trust Fund under any provision of law. (e) Termination of Trust Fund.--The Rehabilitation Trust Fund shall terminate when, upon petition by the Navajo Nation, the Secretary determines that the goals of the Trust Fund have been met. All funds in the Trust Fund on such date shall be transferred to the Treasury. (f) Authorization of Appropriations; Reimbursement of General Fund.--There is hereby authorized to be appropriated for the Former Bennett Freeze Area Rehabilitation Trust Fund such sums as may be necessary for each of fiscal years 2011 through 2025. SEC. 5. MISCELLANEOUS. (a) Expansion of ONHIR Authority.--Section 12 of Public Law 93-531 (25 U.S.C. 640d-11(d)) is amended by adding at the end the following: ``(4) The Commissioner is authorized to carry out a rehabilitation program to redress the effects of Federal development restrictions (commonly referred to as the `Bennett Freeze') in the western portion of the Navajo Reservation. This program shall be limited to housing construction and renovation, infrastructure improvements, and economic development initiatives. ``(5) There are authorized to be appropriated such sums as may be necessary to carry out the program described in paragraph 4.''. (b) Navajo Rehabilitation Trust Fund.--Section 32 of Public Law 93- 531 (25 U.S.C. 640d-30) is amended-- (1) in the first sentence of subsection (f), by striking ``and the United States has been reimbursed for funds appropriated under subsection (f) of this section''; (2) in the first sentence of subsection (g), by striking ``1990, 1991, 1992, 1993, and 1994'' and all that follows through the final period and inserting ``2011, 2012, 2013, 2014, and 2015.''; and (3) in subsection (g), by striking the second sentence. (c) Relocation of Households and Members.--Section 1 of Public Law 93-531 (25 U.S.C. 640d) is amended by adding at the end the following new subsection: ``(f) The Navajo Nation has the right to negotiate and approve an Accommodation Agreement with the Hopi Tribe for any Navajo head of household residing on Hopi Partitioned Land that has not otherwise entered into an Accommodation Agreement but intends to remain on the Hopi Partitioned Land.''. (d) Relinquishment of Accommodation Agreement and Eligibility for Relocation Benefits.--The Navajo-Hopi Land Dispute Settlement Act of 1996 is amended by adding a new section 13 as follows: ``SEC. 13. RELINQUISHMENT OF ACCOMMODATION AGREEMENT AND ELIGIBILITY FOR RELOCATION BENEFITS. ``Notwithstanding any other provision of this Act, the Settlement Agreement, or the Accommodation Agreement, any Navajo family that has entered into an Accommodation Agreement shall have the right-- ``(1) to relinquish that Agreement at any time up until the closure of the Office of Navajo and Hopi Indian Relocation; and ``(2) after relinquishment under paragraph (1), to receive the full relocation benefits to which the family would otherwise have been entitled had the family not signed the Accommodation Agreement, including relocation housing, counseling, and other services.''. (e) Appropriations.--There are authorized to be appropriated such sums as are necessary to carry out the programs set forth in the amendments made by this section. Funds appropriated under this subsection shall be in addition to funds made available for use on the Navajo and Hopi Reservations out of appropriations heretofore or hereafter granted for the benefit, care, or assistance of Indians in general, or made pursuant to other authorizations in effect on the date of the enactment of this Act.

Former Bennett Freeze Area Development Act - Requires the Commissioner of the Office of Navajo and Hopi Indian Relocation (ONHIR), by request of the Navajo Nation or the Hopi Tribe by tribal resolution, to enter into a self-determination contract or contracts with the requesting Indian tribe to plan, conduct, and administer programs, functions, services, or activities, including construction programs administered by the Commissioner that pertain directly to the requesting Indian tribe. Establishes the Former Bennett Freeze Area Rehabilitation Trust Fund in the Treasury. Makes amounts in the Fund available to the Navajo Nation solely for purposes which will contribute to the continuing rehabilitation and improvement of the economic, housing, infrastructure, health, educational, and social condition of families, and Navajo communities, that have been affected by the former Bennett Freeze. Authorizes the Commissioner to carry out a rehabilitation program to redress the effects of federal development restrictions (Bennett Freeze) in the western portion of the Navajo Reservation, limited to housing construction and renovation, infrastructure improvements, and economic development initiatives. Repeals requirements that: (1) the United States be reimbursed for funds appropriated to the Navajo Rehabilitation Trust Fund before its termination; and (2) the income derived by the Navajo Tribe from the surface and mineral estates of certain lands located in New Mexico acquired for the Tribe's benefit be used to reimburse the General Fund of the U.S. Treasury. Reauthorizes the Fund. Grants the Navajo Nation the right to negotiate and approve an Accommodation Agreement with the Hopi Tribe for any Navajo head of household residing on Hopi Partitioned Land that has not otherwise entered into such Agreement but intends to remain on the Land. Amends the Navajo-Hopi Land Dispute Settlement Act of 1996 to grant any Navajo family that has entered into an Accommodation Agreement the right to: (1) relinquish that Agreement at any time up until the closure of the ONHIR; and after such relinquishment (2) receive the full relocation benefits to which the family would otherwise have been entitled had the family not signed such Agreement, including relocation housing, counseling, and other services.

Millions of phony accounts. Fake bank card PIN numbers. Fictitious email accounts. Wells Fargo admitted to firing 5,300 employees for engaging in these shocking tactics. The bank earlier this month paid $185 million in penalties and has since apologized. Now CNNMoney is hearing from former Wells Fargo (WFC) workers around the country who tried to put a stop to these illegal tactics. Almost half a dozen workers who spoke with us say they paid dearly for trying to do the right thing: they were fired. "They ruined my life," Bill Bado, a former Wells Fargo banker in Pennsylvania, told CNNMoney. Bado not only refused orders to open phony bank and credit accounts. The New Jersey man called an ethics hotline and sent an email to human resources in September 2013, flagging unethical sales activities he was being instructed to do. Eight days after that email, a copy of which CNNMoney obtained, Bado was terminated. The stated reason? Tardiness. Related: Elizabeth Warren's epic takedown of Wells Fargo CEO HR official describes 'retaliation' Retaliating against whistleblowers is a major breach of trust. Ethics hotlines are exactly the kind of safeguards put in place to prevent illegal activity from taking place and provide refuge to employees from dangerous work environments. Wells Fargo CEO John Stumpf made precisely that point on Tuesday when he testified before angry Senators. "Each team member, no matter where you are in the organization, is encouraged to raise their hands," Stumpf told lawmakers. He mentioned the anonymous ethics line, adding, "We want to hear from them." But that's not the experience of some former Wells Fargo workers. One former Wells Fargo human resources official even said the bank had a method in place to retaliate against tipsters. He said that Wells Fargo would find ways to fire employees "in retaliation for shining light" on sales issues. It could be as simple as monitoring the employee to find a fault, like showing up a few minutes late on several occasions. "If this person was supposed to be at the branch at 8:30 a.m. and they showed up at 8:32 a.m, they would fire them," the former human resources official told CNNMoney, on the condition he remain anonymous out of fear for his career. CNNMoney spoke to a total of four ex-Wells Fargo workers, including Bado, who believe they were fired because they tipped off the bank about unethical sales practices. Another six former Wells Fargo employees told CNNMoney they witnessed similar behavior at Wells Fargo -- even though the company has a policy in place that is supposed to prevent retaliation against whistleblowers. CNNMoney has taken steps to confirm that the workers who spoke anonymously did work at Wells Fargo and in some cases interviewed colleagues who corroborated their reports. It's possible Wells Fargo could face legal consequences for any retaliation that occurred against employees who called the ethics line. "It is clearly against the law for any company (or executives of such companies) to try to suppress whistleblowing," Harvey Pitt, former chairman of the SEC, told CNNMoney in an email. A number of statutes -- including Sarbanes-Oxley and Dodd-Frank -- "make this unambiguously clear," Pitt said. "I endured harsh bullying ... defamation of character, and eventually being pinned for something I didn't do," said Heather Brock, who was fired earlier this month as a senior business banker at a Wells Fargo branch in Round Rock, Texas. Related: Workers tell Wells Fargo horror stories 'That's retaliation' One such former employee was fired after flagging issues directly to Stumpf, according to Senator Bob Menendez. At the Senate hearing, Menendez read the New Jersey woman's 2011 email to Stumpf, where she described improper sales tactics she felt were "wrong." "Did you read that email?" Menendez asked Stumpf. "I don't remember that one," Stumpf replied. "Okay, well she was fired. ... So much for the safe haven," Menendez said. Several senators spoke about the plight of the mostly 5,300, low-level employees who were fired related to the scandal. The firing certainly took a huge toll on Bado's life. It put a permanent stain on his securities license, scaring off other prospective bank employers. Today, the New Jersey man's house is on the verge of being foreclosed on and he's working part-time, at Shop-Rite. "You wonder where the justice is," Bado said. Ken Springer, a former FBI agent who runs a firm that offers a whistleblower hotline service, was alarmed by the allegations made by former Wells Fargo employees. "That's retaliation. It's a big problem -- and a perfect example of what shouldn't happen," Springer said. "It looks like there's been a terrible breakdown of checks and balances at Wells Fargo." In response to CNNMoney's report, a Wells Fargo spokeswoman said: "We do not tolerate retaliation against team members who report their concerns in good faith." She emphasized that employees are encouraged to immediately report unethical behavior to their manager, HR representative or 24-hour ethics line. Related: Wells Fargo CEO denies orchestrated fraud 'Excessive tardiness' eight days after HR email Wells Fargo confirmed to CNNMoney that Bado had worked there. However, the bank declined to comment on why Bado left and and on the ethics complaint with corresponding report number he cited in emails. "Everything submitted to the EthicsLine is investigated," a Wells Fargo spokeswoman said. While ethics complaints are supposed to be confidential, documents show that Bado did speak out before he was fired. On September 19, 2013, Bado wrote an email to a Wells Fargo HR rep and copied his regional manager, where he detailed improper sales tactics. Documents show Bado was fired -- for "excessive tardiness" -- just eight days later. "I have been asked on several occasions to do things that I know are not ethical and would be grounds for discharge," Bado said in the email to HR. He said a branch manager on "many occasions" asked him to send out a debit card, "pin it," and enroll customers in online banking -- "all without the customers (sic) request or knowledge." Those are precisely the same practices that regulators fined Wells Fargo for three years later and that senators grilled the bank over this week. Lose, lose situation for Heather Brock Brock, the business banker from Texas, told CNNMoney she experienced a similar situation. The 26-year-old single parent of two young boys was fired soon after she contacted the company's ethics line about illegal sales practices she witnessed. Wells Fargo also confirmed Brock used to work at the company but declined to comment further. Brock was fired earlier this month, with Wells Fargo accusing her of falsifying documents -- a charge Brock emphatically denies. Brock said the company bullied her into admitting she did something wrong. A current Wells Fargo employee who works in Brock's branch vouched for her version of events. "That's really scary when you're with a big corporation like this and HR doesn't have your back," said the current employee, who wished to remain anonymous so as not to get fired as well. Brock is hoping her story forces meaningful change at Wells Fargo. "You lose if you do complain and you lose if you don't. What does a powerless employee do?" Brock said. -- To reach the author of this article email [email protected] ||||| Wells Fargo’s former employees don’t agree with CEO John Stumpf’s assessment that they were the rotten apples. While still training at a California Wells Fargo in 2013, Khalid Taha, then a personal banker, was approached by a co-worker and pressed to open a second account under false pretenses. The co-worker told Taha that he couldn’t convert his existing Wells Fargo account into an employee account. She also told him he could buy credit card insurance with no fees. When Taha discovered later, during his ethics training that he had been lied to about both products, he reported the employee. It did not go as expected. “This employee was promoted after a few months,” he said during a press conference hosted by the Committee for Better Banks. See also: Goldman Sachs Bans Employees from Donating to Trump The Committee, which is an organization that says it represents the rights of workers in the financial service industry, brought together a handful of former bank employees on Monday, including two from Wells Fargo, in light of the banking giant’s recent scandal. The Consumer Finance Protection Bureau ordered Wells Fargo to pay $185 million in fines for opening 2 million phony accounts, saying the practice was a result of employees trying to hit aggressive sales targets and receive bonuses. Wells Fargo (wfc) CEO John Stumpf though, seems to have shifted blame for the scandal on to a few bad apples—the 5,300 employees fired (He clarified to CNBC that he did feel accountable, but maintained that nothing in Wells Fargo’s culture had promoted such behavior). See also: Inside Wall Street’s Greatest Feud: Icahn vs. Ackman Yet, both Taha, who left Wells Fargo in July, and former branch manger Julie Miller, who left in 2013, say management was central to allowing to scandal to proliferate. Taha and Miller recalled reporting multiple instances of reporting co-workers for illegally opening deposit and credit card accounts without consumer consent—only to see the same employees promoted or receive a raise later. Meanwhile, the bank continued to set high sales targets for its branches. “I was told by Wells Fargo district and regional management to make my personal bankers and tellers, ‘Sell, Sell, Sell,'” Miller recalled, noting that she had a 35% annual growth target despite being having a finite customer base. “Bankers became so desperate to reach their sales goals to avoid being terminated, that they would ‘churn’ accounts. This is when you close accounts and open up new ones for the same customer in order to manipulate the sales system. See also: Wells Fargo Is No Longer the Most Valuable Bank in the World Taha said that he had to meet sales goals every day, for fear of getting written up or fired. That daily quota often involved 10 to 15 personal accounts, 2 to 3 new accounts, and 2 to 3 credit card accounts. Yet, wages for the average teller was just $12.40 an hour—making the bonuses given for meeting high sales goals necessary in some cases to “make ends meet.” In July, Wells Fargo’s top consumer banking executive Carrie Tolstedt left the bank with $124.6 million in stock and options. The problem with cross-selling, says Shane Larson, the legislative director at Communications Workers of America, is far more pervasive than at just Wells Fargo. The use of aggressive sales targets is an industry can be seen in J.P. Morgan Chase, Bank of America, SunTrust, among others. See also: Wells Fargo Exec Who Headed Phony Accounts Unit Collected $125 Million Former TD Bank employee Cassaundra Plummer noted that her supervisors had encouraged sales practices that weren’t illegal, but certainly dubious. “I was told to drive the conversation, so basically confuse the customer,” she said. She would tell the client that “we’re going to do this and we’re going to do that.” Still, before critics can turn their attention to the consumer banking industry at large, investors are still not mollified by how Wells Fargo has been punished for the scandal. Many are calling for clawbacks the pay of CEO John Stumpf and the executive formerly in charge of community banking, Carrie Tolstedt. Others are calling for resignations. On Tuesday, Stumpf is expected to appear before the Senate in relation to the account scandal. “Corporate executives designed the sales quota systems and created the culture of harassment and fear when we did not meet them,” Miller said. “When John Stumpf blamed the frontline workers for the unauthorized accounts, I was disgusted.”

– More than 5,000 Wells Fargo workers were fired in the phony-accounts scam that's rocked the company—but they weren't the only ones who got pink slips. CNNMoney reports it spoke with a handful of ex-workers who say they were terminated after raising the red flag about the bank's unethical activities, including by calling the company's ethics hotline set up for just that purpose and meant to protect whistleblowers. "They ruined my life," says Bill Bado, a former worker who notes he called the hotline and wrote an email to HR in September 2013 and was fired for tardiness eight days after sending it. The ex-employees say their firings all followed that pattern, with trumped-up charges of being late or other misdeeds. "I endured harsh bullying … defamation of character, and eventually being pinned for something I didn't do," says Heather Brock, canned this month for falsifying documents (she denies it). An anonymous ex-HR worker backs up these claims, telling CNN there was a system in place to get back at those who spoke up, with the company keeping a close eye on whistleblowers until it could find something petty to pin on them to lead to termination. "If this person was supposed to be at the branch at 8:30am and they showed up at 8:32am, they would fire them," he says. One woman says she was fired even after emailing CEO John Stumpf directly about what she thought were shady sales tactics. Wells Fargo's response regarding these allegations: "We do not tolerate retaliation against team members who report their concerns in good faith," a rep says, noting concerned employees can talk to their bosses or HR … or call the ethics hotline. (Fortune documents stories from two other ex-employees that sound strikingly similar.)