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SECTION 1. SHORT TITLE. This Act may be cited as the ``Orphan Highway Restoration Act''. SEC. 2. NATIONAL ORPHAN HIGHWAYS PROGRAM. (a) In General.--Chapter 1 of title 23, United States Code, is amended by adding at the end the following: ``Sec. 167. National orphan highways program ``(a) Grants and Technical Assistance.-- ``(1) In general.--The Secretary shall make grants and provide technical assistance to States and units of local government to-- ``(A) perform preventive maintenance on or carry out projects for resurfacing, restoration, reconstruction, and rehabilitation of an orphan highway; and ``(B) rehabilitate, repair, or construct sidewalks, medians, bike lanes, traffic-calming devices, signaling, or signs to enhance community livability on or adjacent to an orphan highway. ``(2) Priority.--In making grants under this section, the Secretary shall give priority to projects that-- ``(A) include rehabilitation measures that focus on pedestrian safety; ``(B) are coordinated with State and local adopted preservation or development plans; ``(C) promote cost-effective and strategic investments in transportation infrastructure facilities that minimize adverse impacts on the environment; ``(D) promote innovative private sector strategies; ``(E) foster public-private partnerships; ``(F) include a higher percentage of State or locally matched funds; ``(G) have zoning designations that support more intensive, mixed-use development along part or all of the route; or ``(H) upon completion, will result in the transfer of ongoing management and administrative responsibilities from the State to the local jurisdiction. ``(3) Distribution of funds.--The Secretary shall allocate funds made available for this section for fiscal years 2010 through 2015 among the grant recipients, using the latest available census data, as follows: ``(A) Not less than 20 percent of the funds shall used for making grants to units of local government with a population between 50,000 and 250,000 residents. ``(B) Not less than 50 percent of the funds shall be used for making grants to units of local government with a population of less than 50,000. ``(b) Savings Clause.--The Secretary shall not withhold any grant or impose any requirement on a grant recipient as a condition of providing a grant or technical assistance for any orphan highway unless the requirement is consistent with the authority provided in this chapter. ``(c) Federal Share.--The Federal share of the cost of carrying out a project under this section shall be determined in accordance with section 120, except that, in the case of an orphan highway that provides access to or within Federal or Indian land, the head of a Federal land management agency may use funds authorized for such agency for the non-Federal share. ``(d) Administrative Oversight.--A grant recipient may use not more than 2 percent of funds received under this section for administrative costs. ``(e) Definitions.--In this section, the following definitions apply: ``(1) Orphan highway.--The term `orphan highway' means a highway that-- ``(A) is or was formerly a United States numbered highway; ``(B) is located within the boundaries of a unit of local government; ``(C) is no longer a principal route for traffic passing through the State after construction of a bypass or Interstate System route; ``(D) currently functions as a county, parish, or city arterial or collector route, or provides access to or within Federal or tribal lands; and ``(E) because of decreased importance to statewide transportation, has received only routine maintenance but needs significant resurfacing, restoration, reconstruction, or rehabilitation. ``(2) Unit of local government.--The term `unit of local government' means-- ``(A) any city, county, township, town, borough, parish, village, or other general purpose political subdivision of a State; ``(B) any law enforcement district or judicial enforcement district that-- ``(i) is established under applicable State law; and ``(ii) has the authority to, in a manner independent of other State entities, establish a budget and impose taxes; ``(C) an Indian tribe, as that term is defined in section 4 of the Indian Self-Determination and Education Assistance Act (25 U.S.C. 450b); or ``(D) for the purposes of assistance eligibility, any agency of the government of the District of Columbia or the Federal Government that performs law enforcement functions in and for-- ``(i) the District of Columbia; or ``(ii) any Trust Territory of the United States. ``(f) Authorization of Appropriations.--There is authorized to be appropriated out of the Highway Trust Fund (other than the Mass Transit Account) to carry out this section $600,000,000 for each of fiscal years 2010 through 2015.''. (b) Conforming Amendment.--The analysis for such chapter is amended by adding at the end the following: ``167. National orphan highways program.''.

Orphan Highway Restoration Act - Defines "orphan highway" to mean a highway that: (1) formerly was a U.S. numbered highway; (2) no longer is a principal route for traffic passing through a state; and (3) because of decreased importance to statewide transportation, has received only routine maintenance but needs significant restoration. Directs the Secretary of Transportation to: (1) make grants and provide technical assistance to states and local government units to restore orphan highways; and (2) allocate funds to grant recipients for FY2010-FY2015 based on a calculated formula.

although studies of spiral galaxies commonly assume an axisymmetric equilibrium state , possibly perturbed by spiral arms , there is growing evidence that many galaxies lack this symmetry . based on optical appearance , approximately @xmath5 of disk galaxies exhibit significant `` lopsidedness '' ( rix & zaritsky 1995 ; kornreich , haynes , & lovelace 1998 ) which supports the early findings of baldwin , lynden - bell , & sancisi ( 1980 ) . as many as @xmath6 of spiral galaxies show departures from the expected symmetric two horned global hi line profile ( richter & sancisi 1994 ; haynes _ et al . furthermore , hi maps of several galaxies , for example , ngc 3631 ( knapen 1997 ) , ngc 5474 ( rownd , dickey , & helou 1994 ) , and ngc 7217 ( buta _ et al . _ 1995 ) , have revealed offsets between the optical centers of light and their kinematic centers . two examples of kinematically lopsided galaxies have recently be discussed by swaters _ other recent observations such as the _ hubble space telescope _ observations of the nucleus of m31 ( lauer _ et al . _ 1993 ) and the kitt peak 0.9 meter observations of ngc 1073 ( kornreich _ et al . _ 1998 ) indicate that even the optical center of light may be displaced from the center of the optical isophotes of the major part of the galaxy in a significant fraction of cases . the origin of the lopsideness in disk galaxies remains uncertain . et al . _ ( 1980 ) proposed a simple kinematic model in which different rings of the galaxy , assumed non - interacting , are initially shifted from their centered equilibrium positions . the shifted rings precess in the overall gravitational potential in a direction opposite to that of the mass motion . because the precession rate decreases in general with radial distance , an initial disturbance tends to `` wind up '' into a leading spiral arm in a time appreciably less than the hubble time . miller and smith ( 1988 , 1992 ) have made extensive computer simulation studies of the unstable eccentric motion of matter in the nuclei of galaxies which they suggest is pertinent to the off - center nuclei observed in a number of galaxies , for example , m31 , m33 , and m101 . understanding of the origin of the observed disk asymmetries is important because it provides clues to ongoing accretion of gas and the distribution of dark , unseen mass in the halo . schoenmakers , franx , and de zeeuw ( 1997 ) , interpret optical asymmetry as an indicator of asymmetry in the overall galactic potential , and therefore an indicator of the spatial distribution of the dark matter in a galaxy which may have a triaxial distribution . by analyzing the spiral components present in the surface brightness or distribution , the velocity gradient , and therefore , the shape of the gravitational potential , may be uncovered . jog ( 1997 ) has studied of the orbits of stars and gas in a lopsided potential , and shows that lopsided potentials arising from disks alone are not self - consistent ; rather , a stationary lopsided disk may be responding to asymmetries in the halo . zaritsky and rix ( 1997 ) proposed that optical lopsidedness arises from tidal interactions and/or minor mergers . such mergers are often suggested as the most likely contributors to galaxy asymmetry , even when no interacting companions are evident . while galaxies such as ngc 5474 are well - known to be under the tidal influence of neighbors , the apparently long - lived kinematic offsets of other relatively isolated objects , and the common asymmetries in flocculent ( as opposed to tidally induced `` grand design '' ) spiral galaxies , are not explained by simple tidal interaction models , which produce only transient asymmetric features . a further possibility is that an optical disk may be in a quasi - stationary lopsided state in a symmetric potential , as discussed by syer and tremaine ( 1996 ) . in this model , gaseous and stellar matter swirl about the minimum of the halo potential in a state not fully relaxed . the result is a lopsided flow within a symmetric mass distribution . numerical simulations of this situation have been done by levine and sparke ( 1998 ) using a gravitational @xmath7body tree - code method ( see barnes & hut 1989 ) for disk galaxies shifted from the center of the main halo potential . the results are suggestive of lopsidedness with large lifetimes . an @xmath7body simulation study of a rotating spheroidal stellar system including the dynamics of a massive central object by taga and iye ( 1998a ) indicates that the central object goes into a long lasting oscillation similar to those found earlier by miller and smith ( 1988 , 1992 ) and which may explain asymmetric structures observed in m31 and ngc 4486b . a linear stability analysis of a self - gravitating fluid disk including a massive central object also by taga and iye ( 1998b ) indicates a linear instability ( taga & iye 1998b ) . we comment on the relation of this work to the present study in the conclusions section of this work . here , we develop a theory of the dynamics of eccentric perturbations of a disk galaxy residing in a spherical dark matter halo . we represent the disk as a large number @xmath1 of rings as suggested by baldwin _ et al . _ ( 1980 ) ( and lovelace ( 1998 ) for the treatment of disk warping ) . in contrast with baldwin _ _ , the gravitational interactions between the rings is fully accounted for . we show that for general eccentric perturbations , the centers of the rings are shifted _ and _ the azimuthal distribution of matter in the rings is perturbed . the ring representation is analogous to the approach of contopoulos and grsbal ( 1986 , 1988 ) , where self - consistent galaxy models are constructed from a finite set of stellar orbits . section 2 develops a theory for treating eccentric perturbations of a disk galaxy . the assumed equilibrium is first discussed ( 2.1 ) , and a description of the disk perturbations is developed ( 2.2 ) . the representation of the disk in terms of a finite number @xmath1 of rings is presented ( 2.3 ) , and the ring equations of motion are derived ( 2.4 ) . we renormalize the ring equations so as to reduce the nearest ring interactions ( 2.5 ) . the dynamics and influence of the displacement of the center of the galaxy , which may include a massive black hole , is discussed separately ( 2.6 ) . we obtain an energy constant of the motion for the dynamical equations ( 2.7 ) , the lagrangian , and the conserved total canonical angular momentum ( 2.8 ) . we discuss the nature of the precession of a single ring in 3 . in 4 we study the eccentric motion of a disk consisting of two rings and show that this motion is unstable for sufficiently large ring masses . in 5 we study the eccentric motion of one ring including the radial shift of the central mass and show that this situation is unstable for sufficiently large mass of the center and/or of the ring . section 6 presents numerical results for the eccentric dynamics of disk of many rings including the radial shift of the central mass . section 7 summarizes the conclusions of this work . the equilibrium galaxy is assumed to be axisymmetric and to consist of a thin disk of stars and gas and a spheroidal distributions consisting of a bulge component and a halo of dark matter . we use an inertial cylindrical @xmath8 and cartesian @xmath9 coordinate systems with the disk and halo equatorial planes in the @xmath10 plane . the total gravitational potential is written as @xmath11 where @xmath12 is the potential due to the disk , @xmath13 is due to the bulge , and @xmath14 is that for the halo . the galaxy may have a central massive black hole of mass @xmath15 in which case a term @xmath16 is added to the right - hand side of ( 1 ) . the particle orbits in the equilibrium disk are approximately circular with angular rotation rate @xmath17 , where @xmath18 the equilibrium disk velocity is @xmath19 a central black hole is accounted for by adding the term @xmath20 to the right - hand side of ( 2 ) . the surface mass density of the ( optical ) disk is taken to be @xmath21 with @xmath22 and @xmath23 constants and @xmath24 the total disk mass . the potential due to this disk matter is @xmath25 ~,\ ] ] and the corresponding angular velocity is @xmath26~,\ ] ] where @xmath27 and the @xmath28 and @xmath29 are the usual modified bessel functions ( freeman 1970 ; binney & tremaine 1987 , p.77 ) . typical values are @xmath30 and @xmath31 kpc . for these values , @xmath32 km / s . the potential due to the bulge component is taken as a plummer model @xmath33 where @xmath34 is the mass of the bulge and @xmath35 is its characteristic radius ( binney & tremaine 1987 , p.42 ) . we have @xmath36 typical values are @xmath37 and @xmath38 kpc , and for these values @xmath39 . the potential of the halo is taken to be @xmath40 where @xmath41 const is the circular velocity at large distances and @xmath42 const is the core radius of the halo . we have @xmath43 typical values are @xmath44 km / s and @xmath45 kpc . figure 1 shows an illustrative rotation curve . we treat the disk as fluid and use a lagrangian representation for the perturbation as developed by frieman and rotenberg ( 1960 ) . the position vector @xmath46 of a fluid element which at @xmath47 was at @xmath48 is given by @xmath49 that is , @xmath50 is the unperturbed and @xmath51 the perturbed orbit of a fluid element . this description is applicable to _ both _ the disk gas and the disk stars which are in approximately laminar motion with circular orbits . the perturbations of the halo and bulge are assumed negligible compared with that of the disk . for these approximately spheroidal components , the particle motion is highly non - laminar with criss - crossing orbits with the result that their response `` averages out '' the disk perturbation . further , the perturbations are assumed to consist of small in - plane displacements or shifts of the disk matter , @xmath52 with azimuthal mode number @xmath53 . that is , @xmath54 and @xmath55 have @xmath56-dependences proportional to @xmath57 . from equation ( 6 ) , we have @xmath58 . the eulerian velocity perturbation is @xmath59 . therefore , @xmath60 the components of this equation are @xmath61 where @xmath62 and @xmath63 . the main equation of motion is @xmath64 where @xmath65 is the perturbation in the gravitational force ( per unit mass ) , and @xmath66 is the perturbation of the gravitational potential . the pressure force contribution is small compared to @xmath65 by a factor @xmath67 and is neglected , where @xmath68 is the ` thermal ' spread of the velocities of the disk matter . also , note that @xmath69 the components of ( 11 ) give @xmath70 where @xmath71 is the radial epicyclic frequency ( squared ) . the perturbation of the surface mass density of the disk obeys @xmath72 where @xmath73 is the surface density of the equilibrium disk . because @xmath74 , this equation implies @xmath75 the perturbation of the gravitational potential is given by @xmath76 where the integration is over the surface area of the disk . we represent the disk by a finite number @xmath1 of radially shifted plane circular rings . the matter distribution around each ring is also perturbed . an elliptical distortion of a ring corresponds to an @xmath77 which is not considered here . this description is _ general _ for small shifts @xmath78 , where the linearized equations are applicable ( lovelace 1998 ) . of course , the orbit of a single perturbed particle is not in general closed in the inertial frame used . however , the orbit _ is _ closed in an appropriately rotating frame , and this rotation rate is simply the angular precession frequency of the ring @xmath79 discussed below ( baldwin _ et al . the disk is assumed geometrically thin . for the equilibrium disk we take @xmath80~,\ ] ] where @xmath81 is the mass of the @xmath82 ring , @xmath83 is its radius with @xmath84 , and @xmath85 is its width . the motion of the central part of the disk ( @xmath86 ) is treated separately in 2.6 a physical choice for the rings distribution will have the ring spacing of the order of the disk thickness , @xmath87 . further , we assume @xmath88 in order to simplify the calculation of the ring interaction as discussed in appendix a. for example , a possible choice is @xmath89 with @xmath90 kpc , @xmath91 kpc , and @xmath92 . for @xmath93 , the profile of a ring falls to half its maximum value at @xmath94 so that equation ( 15 ) gives a fairly smooth representation of @xmath95 . the perturbation in the disk s surface density is @xmath96 where @xmath97 $ ] . we can express different moments of the perturbed disk in terms of the rings . for example , the center of mass of the disk is @xmath98 where @xmath99 where an integration by parts has been made . we can write in general @xmath100 here , @xmath101 and @xmath102 are the _ ring displacement amplitudes _ : @xmath103 represents the shift of the ring s center , and @xmath102 represents in general both the shift of the ring s center _ and _ the azimuthal displacement of the ring matter . firstly , notice that for @xmath104 and @xmath105 , there is no shift of the ring s center but rather an azimuthal displacement of the ring matter . in this case @xmath106 . secondly , notice that @xmath107 corresponds to a _ rigid _ shift of the ring without azimuthal displacement of the ring matter . for example , a rigid shift in the @xmath108direction has @xmath109 and @xmath110 so that @xmath111 and @xmath112 . in this case , @xmath113 so that @xmath114 . figure 2 shows the nature of perturbations with a shift of the ring s center and with an azimuthal displacement of the ring matter . = 500 equation ( 18 ) now gives @xmath115 for the case of a rigid shift of a ring , @xmath116 , the center of mass position is simply @xmath117 , as expected . similarly , the velocity perturbation of the disk can be written as @xmath118 where @xmath119 evaluation of ( 22 ) gives @xmath120 the influence of the eccentric motion on the rotation curves is discussed at the end of 6.3 . equations ( 12 ) and ( 19 ) give the ring equations of motion , @xmath121 where the @xmath122 subscripts are implicit , where the angular brackets indicate the average over the ring @xmath123 , where @xmath124 , and @xmath125\delta f_\alpha ~,\ ] ] with @xmath126 . we now evaluate the different force terms on the right - hand side of ( 24 ) . for this it is useful to write @xmath127 , where @xmath128 from equation ( 13 ) . the corresponding contributions to the potential , @xmath129 evaluated at @xmath130 are from ( 13 ) , @xmath131 @xmath132}\bigg\ } \oint{d \psi^\prime \over 2\pi}~ { \cos \psi \over r(r , r^\prime ) } ~,\ ] ] and @xmath133 @xmath134 where @xmath135 , @xmath136 \over r \sqrt{2\pi } \delta r_k}~,\ ] ] and @xmath137 . evaluation of the force on the @xmath138 ring due to the other rings gives @xmath139 where the ` tidal coefficients ' are @xmath140 @xmath141 \over r^\prime ~\partial r^\prime } { \partial { \cal k}(r , r^\prime ) \over \partial r } ~,\ ] ] @xmath142 @xmath143 @xmath144 @xmath145 \over r^\prime \partial r^\prime}~ { \cal k}(r , r^\prime ) ~,\ ] ] @xmath146 @xmath147 where @xmath148 and where the @xmath149 integrals are all from @xmath150 to @xmath151 . formal integration by parts of ( 29 ) gives @xmath152 @xmath153 which shows that @xmath154 . also , integration by parts of ( 31 ) gives @xmath155 @xmath156 and this shows that @xmath157 . expressions for the tidal coefficients in terms of elliptic integrals are given in the appendix . following the approach of lovelace ( 1998 ) , we introduce the complex displacement amplitudes @xmath158~,\ ] ] @xmath159~.\ ] ] here , @xmath160 is the amplitude of the shift of the ring s center , and @xmath161 is angle of the shift with respect to the @xmath108axis ; @xmath162 is the amplitude of the azimuthal displacement of the ring matter , and @xmath163 is the angle of the maximum of the ring density also with respect to the @xmath108axis . if @xmath164 and @xmath165 increase with time , the ring precesses in the same sense as the particle motion and we refer to this as _ forward precession_. the opposite case , with @xmath164 and @xmath165 decreasing with time , is termed _ backward precession_. we now combine equations ( 24 ) and ( 28 ) to obtain the ring equations of motion , @xmath166 where @xmath167 , @xmath168 , and @xmath169 . here , we redo the ring equations of motion so as to diminish the strong tidal interactions of nearest neighbor rings due to the terms @xmath170 . first , we rewrite the right - hand side of ( 38 ) as @xmath171+\nonumber\\ { \cal e}_j\sum_{k}(c_{jk } + d_{jk})~,\end{aligned}\ ] ] similarly , we rewrite the right - hand side of ( 39 ) as @xmath172+\nonumber\\ { \delta}_j\sum_{k}\left ( e_{jk } + d_{jk}^\prime \right)~.\end{aligned}\ ] ] we define @xmath173 using the relations @xmath174 , @xmath175 , and equation ( a14 ) of the appendix gives @xmath176 ( if there is a central black hole @xmath15 then the right - hand side of ( 43 ) also has the term @xmath177_j = 3gm_{bh}/r_j^3 $ ] . ) similarly , we define @xmath178 the ring equations of motion now become @xmath179 @xmath180~,\ ] ] @xmath181 @xmath182~.\ ] ] in the large @xmath1 limit , the sums in equations ( 45 ) and ( 46 ) go over to bounded integrals . the diagonal elements , @xmath183 ( and @xmath184 ) , are absent from ( 45 ) and ( 46 ) . note also that the self - interaction of a ring vanishes as it should for the case of a rigid shift where @xmath185 . the dynamical equations ( 45 ) and ( 46 ) do not account for the part of the disk inside the innermost ring @xmath186 . also , there may be a massive black hole @xmath15 near the galaxy center . we treat this central region separately as a point mass @xmath187 , @xmath188 where @xmath189 . the horizontal displacement of the `` center '' is @xmath190 the equation of motion for @xmath191 taking into account the eccentric displacemnts of the rings is @xmath192 where @xmath193 is the complex displacement amplitude of the `` center '' ; @xmath194 , @xmath195 , are the tidal coefficients between the `` center '' and the rings ; and @xmath196 is the angular oscillation frequency of a particle at the galaxy center . from 2.1 , we have @xmath197_0 = gm_b / r_b^3 $ ] and @xmath198_0 = v_{h}^2/r_{h}^2 $ ] . for all of the considered conditions , we find @xmath199 . the influence of the displaced `` center '' on the rings is included by adding the force terms , due to the `` center s '' displacement , to the right - hand sides of equations ( 45 ) and ( 46 ) , @xmath200 @xmath201 where the ellipses denote terms in equations ( 45 ) and ( 46 ) . an energy constant of the motion of the ring system can be obtained by multiplying equation ( 52 ) by @xmath202 and ( 53 ) by @xmath203 ( with @xmath204^*$ ] denoting the complex conjugate ) , adding the two equations , summing over @xmath122 , and dividing by 2 . ( this factor of @xmath205 makes the kinetic energy of a rigidly shifted ring with @xmath206 equal to @xmath207 . ) further , we multiply equation ( 49 ) by @xmath208 and add the result to the previous sum . in this way we find @xmath209 , where @xmath210 @xmath211 @xmath212\ ] ] @xmath213 and where the real vectors @xmath214 and @xmath215 are useful here . by inspection , we find the lagrangian for the ring system @xmath216 , @xmath217 @xmath218\cdot \hat{\bf z } \bigg \}+ { 1\over 2}m_0 ( \dot{\rvecepsilon}_0 ^ 2-\omega_0 ^ 2\rvecepsilon_0 ^ 2)\ ] ] @xmath219 @xmath220 -\sum_j f_{0j}\left(\rvecepsilon_0\cdot \rvecepsilon_j -{1\over 2}\rvecepsilon_0\cdot \rvecdelta_j \right)~,\ ] ] because @xmath221 , the hamiltonian , @xmath222 is a constant of the motion . it is readily verified that @xmath223 . we can make a canonical transformation @xmath224 @xmath225 , @xmath226 to obtain the lagrangian as @xmath227 . note for example that @xmath228 . it is then clear from the azimuthal symmetry of the equilibrium that @xmath229 is invariant under the simultaneous changes @xmath230 , @xmath231 for @xmath232 , where @xmath233 is an arbitrary angle . thus @xmath234 and consequently the total canonical angular momentum of the ring system , @xmath235 is another constant of the motion . evaluating ( 57 ) gives @xmath236 @xmath237+m_0\epsilon_0 ^ 2\dot{\varphi}_0~,\ ] ] where the last term represents the angular momentum of the galaxy center . the last term within the square brackets can also be written as @xmath238 . the constants of the motion @xmath239 and @xmath240 are valuable for checking numerical integrations of the equations of motion ( 52 ) and ( 53 ) . consider the eccentric motion of a particular ring with the other rings not excited . this is _ not _ a self - consistent limit because gravitational interactions will in general excite all of the rings . however this limit is informative . with @xmath241 , @xmath232 , where @xmath79 the ring precession frequency , we get @xmath242{\cal e } + \left[2\omega ( \omega -\omega ) + d~\right]\delta=0~,\quad~~\ ] ] @xmath243{\cal e } + \left[(\omega-\omega)^2 + d\right]\delta = 0~,\ ] ] where the @xmath122 subscripts are implicit , @xmath244 , @xmath245 , and @xmath246 . with @xmath247 , we get @xmath248 for the limit of many rings , the terms involving @xmath249 become negligible , and ( 60 ) can be readily solved to give four real roots if @xmath250 . figure 3a shows the radial dependence of the four ring precession frequencies @xmath251 ( @xmath252 ) corresponding to the four modes of oscillation . these modes are the analogues of the normal modes of vibration of a non - rotating system ( see lovelace 1998 ) . three of the modes in figure 3a have positive frequencies ( @xmath253 for @xmath254 ) so that they have forward precession with @xmath255 these relations follow from ( 36 ) and ( 37 ) because @xmath256 and @xmath257 are constants . the other mode ( @xmath258 ) has @xmath259 and therefore backward precession . figure 3b shows that the two modes @xmath260 have @xmath261 small compared with unity near the inner radius of the disk , @xmath186 . note that @xmath262 corresponds to a pure azimuthal shift of the ring matter without a shift of the ring center . the mode @xmath258 with backward precession has @xmath263 . as mentioned , @xmath264 corresponds to a rigid shift of the ring center . evaluation of the ring energy for the four modes using equation ( 54 ) shows that the modes @xmath265 have _ negative energy _ whereas the modes @xmath266 have positive energy . the negative energy modes are unstable in the presence of dissipation , for example , the force due to dynamical friction ( see for example lovelace 1998 ) . note that for vanishing ring mass ( @xmath267 ) , the middle two roots approach @xmath268^{1/2}$ ] . thus for @xmath269 , there are only three different roots of equation ( 60 ) , @xmath270 and @xmath271 . outside of the central region of a galaxy we have @xmath272 . consequently , the radial dependences of the mode frequencies @xmath273 will tend to `` wrap up '' an initially coherent asymmetry into a tightly wrapped spiral ( in the absence of ring interactions ) . the forward precessing modes ( @xmath274 ) will give a _ trailing _ spiral wave , @xmath275 , ( with respect to the azimuthal motion @xmath276 ) , whereas the backward precessing mode ( @xmath277 ) will give a _ leading _ spiral wave , @xmath278 . the case of mode @xmath258 for non - interacting rings was discussed earlier by baldwin _ et al . _ ( 1980 ) . here , we consider the eccentric motion of a `` disk '' consisting of two interacting rings , one of mass @xmath279 and radius @xmath186 , and the other of mass @xmath280 , radius @xmath281 . the values of @xmath282 , @xmath283 , @xmath284 ( @xmath285 ) are given by equations ( a11 ) , ( 43 ) , and ( 44 ) with the bulge and halo potentials as given in 2.1 . thus the present treatment is _ self - consistent _ ( in contrast with the previous subsection ) . with @xmath286 and @xmath287 proportional to @xmath288 , equations ( 45 ) and ( 46 ) give @xmath289{\cal e}_1 \quad \quad \quad \quad \quad \quad\ ] ] @xmath290\delta_1\ ] ] @xmath291/m_1~,\ ] ] @xmath292\delta_1 \quad \quad \quad \quad \quad \quad\ ] ] @xmath293{\cal e}_1\ ] ] @xmath294/m_1~,\ ] ] @xmath295 { \cal e}_2 \quad \quad \quad \quad \quad \quad\ ] ] @xmath296\delta_2\ ] ] @xmath297/m_2~,\ ] ] @xmath298\delta_2 \quad \quad \quad \quad \quad \quad\ ] ] @xmath299\ ] ] @xmath300/m_2~.\ ] ] for a non - zero solution , the determinant of the @xmath301 matrix multiplying @xmath302 must be zero . this leads to an eighth order polynomial in @xmath79 which can be readily solved ( with maple r. 5 ) for the frequencies of the @xmath303 modes ( @xmath304 ) . = 400 figure 4 shows the behavior , including instability , of a system of two rings of equal mass @xmath305 so that the `` disk '' mass is @xmath306 . for @xmath307 , the modes @xmath266 approach @xmath308 and the modes @xmath309 approach @xmath310 which agrees with the behavior found in 3 . note that for small @xmath4 modes @xmath311 are associated with ring @xmath205 while modes @xmath312 are associated with ring @xmath313 . in the absence of interactions , the rings are stable independent of their mass . as the disk mass increases , the modes @xmath314 approach each other and merge at @xmath315 and give instability with @xmath316 as shown in figure 4b . we refer to this as the `` first instability . '' notice that the onset of instability corresponds to a merging of the positive energy mode @xmath317 of ring @xmath205 with the negative energy mode @xmath318 of ring @xmath313 ( see 3 ) . the interaction of positive and negative energy modes is a well - known instability mechanism ( see for example lovelace , jore , & haynes 1997 ) . at the instability threshold , a dimensionless measure of the ring self - gravity is @xmath319 , where @xmath320 kpc and @xmath321 . the dependence of the growth rate is well fitted by @xmath322 , with the masses in units of @xmath323 and @xmath324 yr . for @xmath325 , there is a `` second instability '' with growth rate @xmath326 . the ratios of the complex perturbation amplitudes can readily be obtained from ( 62 ) - ( 65 ) once the @xmath303 , possibly complex frequencies are known . for the `` first instability , '' for example , for @xmath327 and the same conditions as for figure 4 , we find @xmath328 , @xmath329 ( by choice ) , @xmath330 , and @xmath331 . these values correspond to @xmath332 , @xmath333 , @xmath334 ( by choice ) , and @xmath335 . thus the azimuthal density enhancement in the outer ring _ trails _ the density enhancement of the inner ring . on the other hand , the radial shift of the outer ring _ leads _ the shift of the inner ring . as a second example , for @xmath336 both the `` first '' and `` second '' instability occur . for the `` first '' instability , we again find that the azimuthal density enhancement of the outer ring _ trails _ that of the inner ring , whereas the radial shift of the outer ring _ leads _ that of the inner ring . for the `` second '' instability the situation is different in that _ both _ the azimuthal density enhancement and the radial shift of the outer ring _ trail _ those in the inner ring . specifically , we find @xmath337 , @xmath338 , @xmath334 ( by choice ) , and @xmath339 . note that for both rings , the angle of the radial shift is roughly @xmath340 displaced from the azimuthal density enhancement . the displacement of the center of mass of the ring ( equation 20 ) is dominated by the azimuthal displacement ( @xmath341 and @xmath342 ) . thus having @xmath161 and @xmath163 about @xmath340 out of phase allows the center of mass of each ring to be closer to the origin , and this is a lower energy configuration . consider now the angular momentum of the perturbed two ring system which from ( 58 ) is @xmath343 . for the evaluation of @xmath240 , note that for each of the eight modes , @xmath344 , and @xmath345 , where @xmath346 labels the mode . this implies that @xmath347 thus , for the `` first instability , '' for @xmath348 where @xmath349 , we have @xmath350 , ( which corresponds to forward precession ) , and @xmath351 . for an unstable mode , the coefficients of the six terms in @xmath240 are all grow exponentially . the only possible way in which @xmath352const can be maintained is to have @xmath353 . this relation provides a useful check on the correctness of the calculations . for the `` first instability '' ( @xmath354 ) , we find by evaluating ( 58 ) that @xmath355 . this means that the angular momentum of the inner ring increases while that of the outer ring decreases . thus the instability acts to transfer angular momentum _ inward_. in contrast , for the `` second instability '' ( @xmath356 ) , we find that @xmath357 . thus , the `` second instability '' acts to transfer angular momentum _ outward_. if @xmath358 decreases and @xmath359 increases , then the average radius of ring 1 must decrease and that of ring 2 must increase . therefore , the `` second instability '' may be important for the accretion of matter in a gravitating disk . here , we consider the eccentric motion of a `` disk '' of one ring including the influence of the eccentric motion of the `` center '' @xmath187 which is located at @xmath360 in equilibrium . the mass @xmath187 includes the mass of a central black hole @xmath15 if it is present . the ring perturbation is described by @xmath361 and @xmath362 as given by ( 52 ) and ( 53 ) , while the `` center '' is described by @xmath363 which is given by ( 49 ) . with the perturbations @xmath364 , we find @xmath242{\cal e } + \left[2\omega ( \omega -\omega ) + d~\right]\delta = 2\omega_a^2{\cal e}_0~,\ ] ] @xmath243{\cal e } + \left[(\omega-\omega)^2 + d\right]\delta = ~\omega_a^2 { \cal e}_0~,\ ] ] @xmath365 where @xmath366 and @xmath367 , with @xmath279 and @xmath186 the mass and radius of the ring . for a non - zero solution , the determinant of the @xmath368 matrix multiplying @xmath369 must be zero . this leads to a sixth order polynomial in @xmath79 or @xmath247 which can readily be solved ( with maple , r5 ) for the frequencies of the @xmath370 modes @xmath251 ( @xmath371 ) . we obtain @xmath372\left [ \left ( { w}^{2}+ e\right ) \left ( { w}^{2}+d\right ) -\left ( 2 \omega w+d\right ) ^{2}\right]\ ] ] @xmath373 where the strength of the interaction between the ring and the `` center '' is measured by @xmath374 here , @xmath375 and @xmath376 are defined in ( 59 ) , and @xmath377 is defined in ( 51 ) . figure 5 shows the dependence of the growth rate @xmath378 on the mass of the `` center '' @xmath187 with the mass of the ring held fixed . the associated real part of the frequency is positive . the onset of instability corresponds to the point where two of the six modes with frequencies given by ( 68 ) merge . the merging is again of positive and negative energy modes . the growth rate has to a good approximation the dependence @xmath379 , with @xmath187 in units of @xmath380 and @xmath381 yr . = 500 the ratios of the complex amplitudes follow from ( 67 ) , and for the unstable mode for @xmath382 we find @xmath383 , @xmath384 , @xmath385 , @xmath386 , @xmath387 , @xmath388 ( by choice ) , and @xmath389 which give @xmath390 , @xmath391 , @xmath392 , and @xmath393 , where @xmath394 yr . thus , the radial shift of the ring is roughly @xmath340 away from the maximum of the density enhancement which has @xmath395 ( by choice ) . the shift of the center of mass of the ring ( equation 20 ) is dominated by the azimuthal density enhancement . thus the radial shift and azimuthal displacements are such that the center of mass of the ring moves closer to the origin which is a lower energy configuration . note that the radial shift of the `` center '' _ trails _ the ring center of mass by an angle @xmath396 . hence , the torque of the `` center '' on the ring acts to _ reduce _ the angular momentum of the ring as verified below . at the same time the ring acts to increase the angular momentum of the `` center . '' consider now the angular momentum of the perturbed ring plus `` center '' system which is given by ( 58 ) . following the arguments of the prior section , the sum of the angular momentum of the `` center '' and that of the ring must be zero for a growing mode . the angular momentum of the `` center '' is simply @xmath397 . for a pure mode , we have @xmath398 . as mentioned , the real part of the frequency is positive for the unstable mode and therefore the angular momentum of the `` center '' increases while the angular momentum of the ring decreases . thus , there is a transfer of angular momentum from the ring to the `` center . '' due to the loss of angular momentum the average radius of the ring will decrease . thus the instability may be important for accretion of matter to the galaxy center . for the results presented here , the rings are taken to be uniformly spaced in @xmath399 with radii @xmath400 kpc with @xmath401 kpc and with @xmath402 . the value @xmath403 gives good spatial resolution over all but the inner part of the disk . the outer radius @xmath404 ( in the range say @xmath405 kpc ) has little influence on the eccentric motion described here , as verified by comparing results with @xmath406 kpc those obtained with significantly larger @xmath404 . also , the eccentric motion of the outer disk , say , @xmath407 kpc , is essentially independent of @xmath94 . we first consider in 6.1 the case where the ring masses correspond to the exponential distribution discussed in 2.1 . the inner part of the disk is found to be strongly unstable to eccentric motions and therefore in 6.2 we consider a disk with the mass of the innermost three rings reduced . in 6.3 we consider disks with a smooth reduction in @xmath95 in the inner part of the disk , @xmath408 . we solve ( 52 ) and ( 53 ) numerically as eight first order equations for @xmath409 and @xmath410 , and for @xmath411 and @xmath412 , @xmath232 . at the same time , we solve the two additional equations , @xmath413 @xmath414 to give @xmath415 , which is the angle to the maximum of the radial shift , and @xmath416 , which is the angle to the maximum of the azimuthal density enhancement . these angles are analogous to the line - of - nodes angles for the tilting of the rings of a disk galaxy ( lovelace 1998 ) . thus , we solve @xmath417 first order equations . in all cases , the total energy ( 54 ) and total canonical angular momentum ( 58 ) are accurately conserved . the different frequencies @xmath418 , @xmath419 , and @xmath420 , and the tidal coefficients @xmath421 , etc . , are evaluated using the equations of the appendix . here , we consider the eccentric motion of the rings for the case where @xmath422 with @xmath423 . the mass of the center is assumed given by ( 47 ) , which gives @xmath424 for the parameters of figure 1 . alternatively , this value of @xmath187 could be due in part to a central black hole . figure 6 shows the dependences of the radial shifts @xmath425 and azimuthal displacements @xmath426 of the rings ( @xmath427 ) and the radial shift of the `` center '' @xmath428 at a short time , @xmath429 myr after an initial perturbation . this type of plot is related to the plots emphasized by briggs ( 1990 ) for characterizing the warps of galactic disks ( see also lovelace 1998 ) . the angles @xmath430 and @xmath431 are analogs of the line - of - nodes angle the warp . = 500 = 500 from figure 6 note that the azimuthal displacements @xmath432 are larger than the radial displacements @xmath433 so that the displacement of the center of mass of a ring is dominated by @xmath432 . the eccentric motion of the inner rings , say , @xmath434 or @xmath90 to @xmath435 kpc , show the most rapid , exponential growth . for these rings the angles @xmath163 and @xmath161 are approximately @xmath340 degrees out of phase , and this agrees with the behavior found for the `` second '' instability of two rings discussed in 4 . as mentioned , this allows the center of mass of each ring to move closer to the origin , which is a lower energy configuration . note that with increasing @xmath122 , both @xmath161 and @xmath163 decrease for the inner rings which corresponds to a _ trailing _ pattern the same as found for the second instability of two rings . note also that the shift of the `` center '' @xmath436 trails the shift of the center of mass of the @xmath437 ring in agreement with 5 . thus the torque of the first ring on the center acts to increase the angular momentum of the center while the torque of the center on the first ring decreases the rings angular momentum . figure 7 shows the exponential growth of the azimuthal displacement @xmath438 and radial shift @xmath439 of the first ring and the simultaneous growth of the radial shift of the center @xmath436 . the @xmath440folding time is about @xmath441 myr . for comparison , the period of oscillation of the center is @xmath442 myr for the conditions shown , where @xmath377 is given by ( 51 ) . the growth of the eccentric motion of the inner rings is reduced somewhat if the mass of the center is reduced to @xmath443 ; the @xmath440folding time for in this case is about @xmath444 myr for ring 1 . figure 8 shows the perturbations of the angular momentum of the center @xmath445 and the rings @xmath446 at @xmath447 myr obtained from ( 58 ) . in agreement with 5 and the abovementioned direction of the torque , the angular momentum of the center increases while that of the first and second ring decrease . the decrease in angular momenta of these rings will result in their radii shrinking . note that the center rotates in the same direction as the disk matter . = 500 the present linear theory does not address the issue of saturation of growth of the eccentric motion . one possibility is that the strong instability of the inner rings of the disk leads to the destruction of this part of the disk . here , we consider the eccentric motion of the rings for the case where the ring masses are the same as in 6.1 _ except _ that @xmath448 , @xmath449 , and @xmath450 , which are the rings with radii @xmath90 , @xmath451 , and @xmath452 kpc . the mass of the center is the same as in 6.1 , @xmath453 . the disk mass is reduced by a factor @xmath454 compared with an exponential disk . the aim of reducing @xmath455 is to reduce the growth rate of the eccentric motion of this part of the disk . = 500 figure 9 shows the essential behavior in a polar plot of the displacements and shifts at two times . the radial shift of the center is negligible on the scale of this figure . the @xmath440folding time for ring 3 is about @xmath456 myr . notice that the curves traced out by @xmath432 and by @xmath433 are approximated straight lines from the origin which rotate rigidly in the direction of motion of the matter for @xmath457 to about @xmath458 , which corresponds to @xmath459 to @xmath460 kpc . the instantaneous period of rotation of this pattern is @xmath461 myr , which is longer that the oscillation period at the center , @xmath462 myr . this case is an example of the _ phase - locking _ of the eccentric motion of these rings due to the self - gravity between the rings . this phase - locking is analogous to that which occurs in the tilting motion of the rings representing a disk galaxy due to self - gravity ( lovelace 1998 ) . in the case of tilting of rings the phase - locking results in the line - of - node angles of the rings in the inner part of the disk becoming the same . also in this case the growth of the eccentric instability of the inner rings is sufficiently fast that it probably further disrupts the inner part of the disk . here , we study the eccentric motion of a disk the inner part of which is attenuated relative to an exponential disk . specifically , the rings masses are @xmath463 @xmath464 , where @xmath465 with @xmath466const . we consider @xmath467 . the mass of the center is the same as in 6.1 , @xmath453 . however , the motion of the center is negligible and value @xmath187 has little influence on the eccentric motion of the disk described below . the disk mass is smaller than for an exponential disk by a factor @xmath468 . = 500 = 500 = 500 = 500 figure 10 shows the essential behavior in a polar plot of the shifts and displacements at two times . the shift of the center is negligible on the scale of the plot . the magnitude of azimuthal displacement of the outer ring @xmath469 exhibits an approximately _ linear _ growth with time , @xmath470 , for the considered initial conditions and @xmath471 gyr . in contrast , the magnitude of the radial shifts @xmath433 remains bounded by its initial maximum value @xmath472 . = 500 the patterns formed by both @xmath432 and @xmath433 in figure 10 are _ trailing _ spirals . this is different from the proposal of baldwin _ et al . _ ( 1980 ) that leading spirals should form . the rotation of the outer point on the spiral @xmath473(@xmath406 kpc ) in figure 10 is in the direction of rotation of the disk matter . its pattern speed @xmath474 corresponds to a period @xmath475 myr , which is a factor @xmath476 longer than the rotation period of matter at this radius ( @xmath477 myr ) . the pattern period of say @xmath478 is @xmath479 myr , which is a less than the rotation period of the matter at this radius ( @xmath480 myr ) . thus , it is evident that the spiral is `` wrapping up '' as time increases . at the same time , the spiral pattern propagates radially outward . the outward speed is about @xmath481 km / s at @xmath482 kpc for @xmath483 myr . figure 11 shows a polar plot of the radius to the maximum of the azimuthal displacement @xmath484 at two times . the curve is a trailing spiral with an approximate fit given by @xmath485 where @xmath486 @xmath487 rad , and @xmath488 @xmath489 kpc for @xmath471 gyr . thus the radial spacing between spiral arms is @xmath490 for @xmath491 . for validity of the ring representation we must have @xmath492 kpc ) , where @xmath94 the separation between rings . figure 12 shows the radial variation of the perturbations in ring angular momenta . the perturbation of the angular momentum of the central mass is negligible . this figure should be compared with figure 8 which gives the same plot for an exponential disk . some simplification of equations is possible in the present case at long times due to the fact that @xmath493 . firstly , we have @xmath494 with @xmath495 secondly , @xmath496 for @xmath497 . figure 13 shows the profiles along the @xmath108axis through the galaxy center of the fractional change in the surface density @xmath498 and the change in the azimuthal velocity @xmath499 obtained from ( 74 ) and ( 75 ) . the opposite signs of @xmath499 on the two sides of the galaxy would of course make the rotation curves on the two sides different as observed in some cases ( swaters _ et al . note that in some regions the changes @xmath500 and @xmath499 are correlated and in other regions they are anticorrelated . figure 14 shows two - dimensional appearance of the fractional surface density variations from ( 75 ) . for long times @xmath501 gyr , the the azimuthal displacements and shifts of the inner rings ( @xmath205 and @xmath502 ) start to become large compared with the values in the outer disk ( @xmath503 kpc ) even though these rings have very small masses . at the same time , the displacement of the center , which has mass @xmath504 , grows , and at @xmath505 gyr it is @xmath506 for the conditions of figures 9 - 13 . if the mass of the center is @xmath507 , then the displacements and shifts of rings @xmath205 and @xmath502 at @xmath505 gyr are significantly reduced as is the shift of the center which is @xmath508 . the paper develops a theory of eccentric ( @xmath509 ) linearized perturbations of an axisymmetric disk galaxy residing in a spherical dark matter halo and with a spherical bulge component . the disk is represented by a large but finite number @xmath1 of rings with shifted centers _ and _ with perturbed azimuthal matter distributions . this description is appropriate for a disk with small ` thermal ' velocity spread @xmath68 where the matter is in approximately laminar circular motion . the spread for a thin disk has @xmath67 , but it is sufficent to give a toomre @xmath510 . earlier , baldwin _ et al . _ ( 1980 ) discussed asymmetries in disk galaxies in terms of shifted rings but without interactions between the rings and without azimuthal displacements of the ring matter . account is taken of the shift of the matter at the galaxy s center , which may include a massive black hole . the gravitational interactions between the rings and between the rings and the center is fully accounted for , but the halo and bulge components are treated as passive gravitational field sources . equations of motion are derived for the ring and the center , and from these we obtain the lagrangian for the rings@xmath2center system . for this system we derive an energy constant of the motion , and a total canonical angular momentum constant of the motion . we first discuss the nature of the precession of a single ring with the other rings fixed ; this case although not self - consistent is informative . there are four modes , analogs to the normal modes of a non - rotating system , and two have negative energy and two positive energy . negative energy modes are unstable in the presence of dissipation such as that due to dynamical friction . we go on to study the eccentric motion of a disk consisting of two rings of different radii but equal mass @xmath3 . above a threshold value of @xmath4 the two rings are unstable with instability due merging of positive and negative energy modes . this result is obtained by solving the eighth order polynomial for the frequencies of the eight modes . above a second , somewhat larger threshold value of @xmath4 , a second instability appears , and in this case the ring motion is such that the angular momentum of the inner ring decreases while that of the outer ring increases . for the unstable motion , the maximum of the azimuthal density enhancement of a ring occurs at an angle about @xmath340 from the direction of the radial shift . this allows the center of mass of the ring to move closer to the center of mass of the other ring and to the origin . we also analyze the eccentric motion of a disk of one ring interacting with a radially shifted central mass . this system has six modes , the frequencies of which are obtained by solving a sixth order polynomial . in this case , instability sets in above a threshold value of the central mass ( for a fixed ring mass ) , and it acts to increase the angular momentum of the central mass ( which therefore rotates in the direction of the disk matter ) , while decreasing the angular momentum of the ring . the instability is again due to the merging of positive and negative energy modes . we study the eccentric dynamics of a disk with an exponential surface density distribution represented by a large number @xmath403 of rings and a central mass @xmath511 which may include the mass of a black hole . the outer radius of the disk is @xmath512 kpc ; we have checked that this value has negligible affect on the reported results . in this case , we numerically integrate the equations of motion . a check on the validity of the integrations is provided by monitoring the mentioned total energy and total canonical angular momentum , which are found to be accurately constant in all presented results . the inner part of the disk @xmath513 kpc is found to be strongly unstable with @xmath440folding time @xmath514 myr for the conditions considered . the @xmath440folding time is somewhat longer if @xmath515 . angular momentum of the rings is transferred _ outward _ , _ and _ to the central mass if it is present . a _ trailing _ one - armed spiral wave is formed in the disk . this differs from the prediction of baldwin _ et al . _ ( 1980 ) of a leading one - armed spiral . the outer part of the disk @xmath516 is stable and in this region the angular momentum is transported by the wave . thus our results appear compatible with the theorem of goldreich and nicholson ( 1989 ) regarding angular momentum in _ stable _ rotating fluids . the instability found here appears qualitatively similar to that found by taga and iye ( 1998b ) for a fluid kuzmin disk with surface density @xmath517 with a point mass at the center where unstable trailing one - armed spiral waves are found . the present linear theory does not address the issue of saturation of growth of the eccentric motion . one possibility is that the strong instability of the inner rings of the disk leads to the destruction of this part of the disk . for this reason we have studied a disk with a modified exponential density distribution where the surface density of the inner part of the disk is reduced . however , the mass of the center of the galaxy was kept the same as in the case of an exponential disk , @xmath518 . in this case we find much slower , linear - as opposed to exponential - growth of the eccentric motion of the disk for times @xmath519 gyr . a trailing one - armed spiral wave forms in the disk and becomes more tightly wrapped as time increases . angular momentum is transferred outward . the motion of the central mass if present is small compared with that of the disk for @xmath519 gyr . for long times @xmath501 gyr , the the azimuthal displacements and shifts of the inner rings start to become large compared with the values in the outer disk . at the same time , the radial shift of the center grows . this shift is significantly reduced if the mass of the center is changed from @xmath520 to @xmath521 . baldwin , j.e . , lynden - bell , d. & sancisi , r. 1980 , , 193 , 313 barnes , j.e . , & hut , p. 1989 , , 70 , 389 binney , j. , & tremaine , s. 1987 , galactic dynamics ( princeton : princeton university press ) briggs , f.h . 1990 , apj , 352 , 15 buta , r. , van driel , w. , braine , j. , combes , f. , wakamatsu , k. , sofue , y. , & tomita , a. 1995 . , 450 , 593 contopoulos , g. , & grosbl , p. 1986 , a&a , 155 , 11 contopoulos , g. , & grosbl , p. 1988 , a&a , 197 , 83 freeman , k.c . 1970 , , 160 , 811 frieman , e. , & rotenberg , m. 1960 , rev . phys . , 32 , 898 goldreich , p. , & nicholson , p.d . 1989 , , 342 , 1075 haynes , m.p . , hogg , d.e . , maddalena , r.j . , roberts , m.s . , & van zee , l. 1998a , , 115 , 62 ichimaru , s. 1973 , _ basic principles of plasma physics _ ( benjamin : reading , massachusetts ) , ch . 4 jog , c.j . 1997 , , 488 , 642 knapen , j.h . 1997 , , 286 , 403 kornreich , d.a . , haynes , m.p . , & lovelace , r.v.e . 1998 , aj , 116 , 2154 lauer , t.r . , faber , s.m . , groth , e.j . , shaya , e.j . , campbell , b. , code , a. , currie , d.g . , baum , w.a . , ewald , s.p . , hester , j.j . , holtzman , j.a . , kristian , j. , light , r.m . , ligynds , c.r . , oneil , e.j . , jr . , & westphal , j.a . 1993 , , 106 , 1436 levine , s.e . , & sparke , l.s . 1998 , , 496 , l13 lovelace , r.v.e . , jore , k.p . , & haynes , m.p . 1997 , , 475 , 83 lovelace , r.v.e . 1998 , a&a , 338 , 819 miller , r.h . , & smith , b.f . 1988 , in _ applied mathematics , fluid mechanics , and astrophysics : a symposium in honor of c.c . lin_. d.j . benney , f.h . shu , & c. yuan , eds . ( singapore : world scientific ) , p. 366 miller , r.h . , & smith , b.f . 1992 , , 393 , 508 richter , o .- g . & sancisi , r. 1994 . , 290 , l9 rix , h .- w . , & zaritsky , d. 1995 , , 447 , 82 rownd , b.k . , dickey , j.m . , & helou , g. 1994 , , 108 , 1638 schoenmakers , r.h.m . , franx , m. , & de zeeuw , p.t , 292 , 349 swaters , r.a . , schoenmakers , r.h.m . , sancisi , r. , & van albada , t.s . 1998 , , in press ( astro - ph/9811424 ) syer , d. , & tremaine , s. 1996 , , 281 , 925 taga , m. , & iye , m. 1998a , , 299 , 111 taga , m. , & iye , m. 1998b , , 299 , 1132 zaritsky , d. , & rix , h .- w . 1997 . , 477 , 118 for @xmath522 , the ring profiles can be treated as delta functions , @xmath523 , and consequently the ` tidal coefficients ' of equations ( 29 ) - ( 32 ) can be simplified to give @xmath524~,\\ d^{\prime}_{jk } & \approx & gm_jm_k~ { \partial { \cal k}(r_j , r_k ) \over r_j ~\partial r_k}= d_{kj}~,\\ e_{jk } & \approx & gm_jm_k~{{\cal k}(r_j , r_k ) \over r_j ~r_k}= { gm_jm_k\over \pi r_j^2 r_k^2 ( r_j+r_k ) } \bigg[(r_j^2+r_k^2)k(k_{jk})-(r_j+r_k)^2 e(k_{jk } ) \bigg]~,\end{aligned}\ ] ] ( mathematica v. 3 ) where @xmath525 , where @xmath526 is defined by equation ( 31 ) , and where @xmath527 are complete elliptic integrals of the first and second kinds respectively . note that for @xmath528 , @xmath529 , @xmath530 , @xmath531 , and @xmath532 . in the opposite limit where @xmath533 , equations ( 27)-(30 ) can be evaluated approximately as @xmath534~,\end{aligned}\ ] ] where @xmath535 , @xmath536 , @xmath537 , and and @xmath538 . the integral in ( a5 ) is a principal value integral of the form occurring in the plasma dispersion function w ( ichimaru 1973 ) . also , @xmath539 -2\pi(\bar r/\delta r)\exp(-u^2/4 ) { \rm erfi}(u/2 ) \bigg \}~,\end{aligned}\ ] ] and @xmath540 equations ( a1 ) - ( a8 ) are valuable for numerical evaluation of the tidal coefficients . in the following we derive some useful relations involving the tidal coefficients . from equation ( 12 ) we have @xmath541^{3/2}}~.\ ] ] the @xmath542 integral in this case is @xmath543 } \left [ ( r+r^\prime ) e + ( r - r^\prime)k \right]~.\ ] ] comparison with ( a2 ) shows that shows that @xmath544 this expression does not include the disk mass within the inner ring . as discussed in 2.6 , this part of the disk is treated as a point mass @xmath187 with unperturbed position @xmath360 . if there is a central black hole @xmath15 , its mass is include in @xmath187 . to account for the influence of @xmath187 , we simply add the term @xmath545 to the right hand side of ( a11 ) . the resulting expression for @xmath546 is useful for the numerical calculations . for @xmath547 and @xmath548 to @xmath549 kpc , we find that equation ( a11 ) gives accurate agreement with the analytic expression ( 3 ) . an alternative expression for @xmath550 can be obtained by integration by parts , @xmath551 thus @xmath552 \over \partial r}~,\ ] ] or @xmath553 \over \partial r^\prime } -{s(r^\prime|r_k ) \over r^\prime}\bigg ] \bigg [ { { \cal k}(r , r^\prime ) \over r } - { \partial { \cal k}(r , r^\prime ) \over \partial r } \bigg]\ ] ] in view of equations ( 27 ) - ( 30 ) , this equation can be written as @xmath554 this relation is useful in 2.5 . we also evaluate the disk gravitational potential in the ring representation , @xmath555^{1/2 } } \nonumber\\ & = & -2\pi g\int r^\prime dr^\prime~ \sigma_d(r^\prime ) { 2 k(k ) \over \pi ( r+r^\prime)}~.\end{aligned}\ ] ] with @xmath556 where @xmath557 for @xmath558 , @xmath559 whereas for @xmath560 @xmath561~,\ ] ] where @xmath562 as above . note that @xmath563 and that @xmath564 .

a theory is developed for the dynamics of eccentric perturbations @xmath0 $ ] of a disk galaxy residing in a spherical dark matter halo and including a spherical bulge component . the disk is represented as a large number @xmath1 of rings with shifted centers _ and _ with perturbed azimuthal matter distributions . account is taken of the dynamics of the shift of the matter at the galaxy s center which may include a massive black hole . the gravitational interactions between the rings and between the rings and the center is fully accounted for , but the halo and bulge components are treated as passive gravitational field sources . equations of motion and a lagrangian are derived for the ring@xmath2center system , and these lead to total energy and total angular momentum constants of the motion . we first study the eccentric motion of a disk consisting of two rings of different radii but equal mass , @xmath3 . for small @xmath4 the two rings are stable , but for @xmath4 larger than a threshold value the rings are unstable with a dynamical time - scale growth . for @xmath4 sufficiently above this threshold , the instability acts to decrease the angular momentum of the inner ring , while increasing that of the outer ring . the instability results from the merging positive and negative energy modes with increasing @xmath4 . secondly , we analyze the eccentric motion of one ring interacting with a radially shifted central mass . in this case instability sets in above a threshold value of the central mass ( for a fixed ring mass ) , and it acts to increase the angular momentum of the central mass ( which therefore rotates in the direction of the disk matter ) , while decreasing the angular momentum of the ring . thirdly , we study the eccentric dynamics of a disk with an exponential surface density distribution represented by a large number of rings . the inner part of the disk is found to be strongly unstable . angular momentum of the rings is transferred outward _ and _ to the central mass if present , and a trailing one - armed spiral wave is formed in the disk . fourthly , we analyze a disk with a modified exponential density distribution where the density of the inner part of the disk is reduced . in this case we find much slower , linear growth of the eccentric motion . a trailing one - armed spiral wave forms in the disk and becomes more tightly wrapped as time increases . the motion of the central mass if present is small compared with that of the disk . epsf.def = cmmib10 at 10pt

SECTION 1. SHORT TITLE. This Act may be cited as the ``Holocaust Rail Justice Act''. SEC. 2. CONGRESSIONAL FINDINGS. Congress finds as follows: (1) During World War II, more than 75,000 Jews and thousands of other persons were deported from France to Nazi concentration camps, on trains operated for profit by the Societe Nationale des Chemins de fer Francais (in this Act referred to as ``SNCF''), including deportations to Auschwitz and Buchenwald. Numerous citizens and residents of the United States were among those who were on the trains or had relatives on the trains. United States servicemen who were pilots shot down over France were also among the persons deported on the SNCF trains to Nazi concentration camps. (2) United States citizens and others have sought redress against SNCF by filing a class action suit in the United States District Court for the Eastern District of New York. The named plaintiffs and class members include United States Army Air Force pilots and United States citizens. (3) The complaint filed alleges that SNCF, a separate corporate entity that remained independent during World War II, operated the deportation trains for a profit, as ordinary commercial transactions. SNCF remained under French civilian control throughout World War II and is alleged to have collaborated willingly with the German Nazi regime. (4) The complaint alleges that SNCF provided the necessary rolling stock, scheduled the departures, and supplied the employees to operate the trains bound for the concentration camps. SNCF allegedly charged an ordinary passenger coach fare for the deportations, calculated per person and per kilometer, and considered these trains as ordinary commercial activities. The plaintiffs further contend that SNCF herded as many people as possible into each car, requiring passengers of all ages and sexes, including the elderly and young children, to stand throughout the trip of several days' duration, with no provision for food or water and no sanitary facilities. The complaint further alleges that SNCF cleaned the trains after each trip, removing the corpses of persons who perished during transit due to the execrable conditions of the train cars. The destination was in each case a camp in which the deportees were to be exterminated, worked to death, or made to suffer terrible and inhuman conditions. (5) The complaint contends that SNCF's actions violated the Principles of the Nuremberg Tribunal, 1950, relating to crimes under international law (earlier recognized by the Martens Clause of the Hague Convention IV of 1907), and aided and abetted the commission of war crimes and crimes against humanity. SNCF has not denied its actions and has never disgorged the money that it was paid for the deportations or otherwise compensated the deportees or their heirs. (6) SNCF's records concerning the deportation trains have not been made available to the plaintiffs, and SNCF archives concerning its wartime activities are not accessible to the general public. (7) SNCF moved to dismiss the lawsuit on a claim of sovereign immunity under the foreign sovereign immunities provisions of title 28, United States Code (28 U.S.C. 1330 and 1602 et seq.), even though it is one of the 500 largest corporations in the world, earns hundreds of millions of dollars from its commercial activities in the United States, and is not accorded sovereign immunity under the laws of France. SNCF's motion to dismiss the lawsuit was granted by the United States District Court for the Eastern District of New York. Plaintiffs appealed the decision, their appeal was granted, and the case was remanded for further proceedings. Subsequently, in light of Republic of Austria v. Altmann, 541 U.S. 677 (2004), in November 2004, on remand, the Court of Appeals for the Second Circuit recalled its prior mandate and determined that SNCF was entitled to immunity and affirmed the dismissal of the complaint. The Second Circuit stated that ``the railroad's conduct at the time lives on in infamy'' but concluded that ``the evil actions of the French national railroad's former private masters in knowingly transporting thousands to death camps during World War II are not susceptible to legal redress in Federal court today.''. (8) This lawsuit, which arises from the unique historical facts of the deportation of persons to Nazi concentration camps, presents issues of substantial importance to citizens and veterans of the United States. Many of those who have sought redress against SNCF are elderly and would have difficulty traveling outside the United States in order to pursue their claims elsewhere. The courts of the United States are and should be a proper forum for this lawsuit. The Foreign Sovereign Immunities Act of 1976, which had not been enacted at the time of SNCF's actions during World War II, was not intended to bar suit against the SNCF. SEC. 3. ACCESS TO UNITED STATES COURTS FOR HOLOCAUST DEPORTEES. (a) Jurisdiction of District Courts.--The United States district courts shall have original jurisdiction, without regard to the amount in controversy, of any civil action for damages for personal injury or death that-- (1) arose from the deportation of persons to Nazi concentration camps during the period beginning on January 1, 1942, and ending on December 31, 1944; and (2) is brought by any such person, or any heir or survivor of such person, against a railroad that-- (A) owned or operated the trains on which the persons were so deported; and (B) was organized as a separate legal entity at the time of the deportation, whether or not any of the equity interest in the railroad was owned by a foreign state. (b) Other Laws Not Applicable.--Sections 1330 and 1601 through 1611 of title 28, United States Code, or any other law limiting the jurisdiction of the United States courts, whether by statute or under common law, shall not preclude any action under subsection (a). (c) Inapplicability of Statutes of Limitation.--An action described in subsection (a) shall not be barred by a defense that the time for bringing such action has expired under a statute of limitations. (d) Applicability.--This section shall apply to any action pending on January 1, 2002, and to any action commenced on or after that date. SEC. 4. REPORTING. In furtherance of international education relating to the Holocaust and historic and continuing anti-Semitism in Europe and throughout the world, the Secretary of State shall submit to the Congress a one-time report, outlining the status of access to wartime records and archives concerning the wartime activities of any railroad organized as a separate legal entity that engaged in the deportation of persons to Nazi concentration camps during the period beginning on January 1, 1942, and ending on December 31, 1944.

Holocaust Rail Justice Act - Grants U.S. district courts original jurisdiction over any civil action for damages for personal injury or death that: (1) arose from the deportation of persons to Nazi concentration camps between January 1, 1942, and December 31, 1944, and (2) is brought by or on behalf of such person against a railroad that owned or operated the trains on which the persons were deported and that was organized as a separate legal entity. Declares that: (1) no law limiting the jurisdiction of the U.S. courts shall preclude any such action, and (2) no such action shall be barred because a statute of limitations has expired. Makes this Act applicable to any action pending on or commenced after January 1, 2002. Directs the Secretary of State to report to Congress on the status of access to wartime records and archives concerning the wartime activities of any such railroad that engaged in the deportation of such persons to Nazi concentration camps.

SECTION 1. SHORT TITLE. This Act may be cited as the ``Energy Research Act of 2007''. SEC. 2. ADVANCED RESEARCH PROJECTS ADMINISTRATION-ENERGY. (a) Establishment.--There is established the Advanced Research Projects Administration-Energy (referred to in this section as ``ARPA- E''). (b) Goals.--The goals of ARPA-E are to reduce the quantity of energy the United States imports from foreign sources and to improve the competitiveness of the United States economy by-- (1) promoting revolutionary changes in the critical technologies that would promote energy competitiveness; (2) turning cutting-edge science and engineering into technologies for energy and environmental application; and (3) accelerating innovation in energy and the environment for both traditional and alternative energy sources and in energy efficiency mechanisms to-- (A) reduce energy use; (B) decrease the reliance of the United States on foreign energy sources; and (C) improve energy competitiveness. (c) Director.-- (1) In general.--ARPA-E shall be headed by a Director (referred to in this section as the ``Director'') appointed by the President. (2) Positions at level v.--Section 5316 of title 5, United States Code, is amended by adding at the end the following: ``Director, Advanced Research Projects Administration- Energy.''. (d) Duties.-- (1) In general.--In carrying out this section, the Director shall award competitive grants, cooperative agreements, or contracts to institutions of higher education, companies, or consortia of such entities (which may include federally funded research and development centers) to achieve the goal described in subsection (b) through acceleration of-- (A) energy-related research; (B) development of resultant techniques, processes, and technologies, and related testing and evaluation; and (C) demonstration and commercial application of the most promising technologies and research applications. (2) Small-business concerns.--The Director shall carry out programs established under this section, to the maximum extent practicable, in a manner that is similar to the Small Business Innovation Research Program established under section 9 of the Small Business Act (15 U.S.C. 638) to ensure that small- business concerns are fully able to participate in the programs. (e) Personnel.-- (1) Program managers.-- (A) Appointment.--The Director shall appoint employees to serve as program managers for each of the programs that are established to carry out the duties of ARPA-E under this section. (B) Duties.--Program managers shall be responsible for-- (i) establishing research and development goals for the program, as well as publicizing goals of the program to the public and private sectors; (ii) soliciting applications for specific areas of particular promise, especially areas for which the private sector cannot or will not provide funding; (iii) selecting research projects for support under the program from among applications submitted to ARPA-E, based on-- (I) the scientific and technical merit of the proposed projects; (II) the demonstrated capabilities of the applicants to successfully carry out the proposed research project; and (III) such other criteria as are established by the Director; and (iv) monitoring the progress of projects supported under the program. (2) Other personnel.-- (A) In general.--Subject to subparagraph (B), the Director shall appoint such employees as are necessary to carry out the duties of ARPA-E under this section. (B) Limitations.--The Director shall appoint not more than 250 employees to carry out the duties of ARPA-E under this section, including not less than 180 technical staff, of which-- (i) not less than 20 staff shall be senior technical managers (including program managers designated under paragraph (1)); and (ii) not less than 80 staff shall be technical program managers. (3) Experimental personnel authority.--In appointing personnel for ARPA-E, the Director shall have the hiring and management authorities described in section 1101 of the Strom Thurmond National Defense Authorization Act for Fiscal Year 1999 (Public Law 105-261; 5 U.S.C. 3104 note). (4) Maximum duration of employment.-- (A) Program managers and senior technical managers.-- (i) In general.--Subject to clause (ii), a program manager and a senior technical manager appointed under this subsection shall serve for a term not to exceed 4 years after the date of appointment. (ii) Extensions.--The Director may extend the term of employment of a program manager or a senior technical manager appointed under this subsection for not more than 4 years through 1 or more 2-year terms. (B) Technical program managers.--A technical program manager appointed under this subsection shall serve for a term not to exceed 6 years after the date of appointment. (5) Location.--The office of an officer or employee of ARPA-E shall not be located in the headquarters of the Department of Energy. (f) Transactions Other Than Contracts and Grants.-- (1) In general.--To carry out projects through ARPA-E, the Director may enter into transactions (other than contracts, cooperative agreements, and grants) to carry out advanced research projects under this section under similar terms and conditions as the authority is exercised under section 646(g) of the Department of Energy Organization Act (42 U.S.C. 7256(g)). (2) Peer review.--Peer review shall not be required for 75 percent of the research projects carried out by the Director under this section. (g) Prizes for Advanced Technology Achievements.--The Director may carry out a program to award cash prizes in recognition of outstanding achievements in basic, advanced, and applied research, technology development, and prototype development that have the potential for application to the performance of the mission of ARPA-E under similar terms and conditions as the authority is exercised under section 1008 of the Energy Policy Act of 2005 (42 U.S.C. 16396). (h) Coordination of Activities.--The Director-- (1) shall ensure that the activities of ARPA-E are coordinated with activities of Department of Energy offices and outside agencies; and (2) may carry out projects jointly with other agencies. (i) Report.--Not later than September 30, 2008, the Director shall submit to Congress a report on the activities of ARPA-E under this section, including a recommendation on whether ARPA-E needs an energy research laboratory. (j) Authorization of Appropriations.--There are authorized to be appropriated to carry out this section-- (1) $300,000,000 for fiscal year 2008; (2) $600,000,000 for fiscal year 2009; (3) $1,100,000,000 for fiscal year 2010; (4) $1,500,000,000 for fiscal year 2011; and (5) $2,000,000,000 for fiscal year 2012.

Energy Research Act of 2007 - Establishes the Advanced Research Projects Administration - Energy (ARPA-E) to reduce foreign energy imports and to improve the competitiveness of the U.S. economy by: (1) promoting revolutionary changes in the critical technologies that would promote energy competitiveness; (2) turning cutting-edge science and engineering into technologies for energy and environmental application; and (3) accelerating innovation in energy and the environment for both traditional and alternative energy sources and in energy efficiency mechanisms to reduce energy use. Requires the ARPA-E Director to award competitive grants, cooperative agreements, or contracts to institutions of higher education, companies, or consortia of such entities (which may include federally funded research and development centers). Requires the Director to implement such programs in a manner similar to the Small Business Innovation Research Program in order to ensure that small-business concerns are fully able to participate in the programs. Authorizes the Director to carry out a program to award cash prizes in recognition of outstanding achievements with potential application to the mission of ARPA-E.

osteoporosis is a skeletal disorder characterized by compromised bone strength predisposing a person to an increased risk of fracture . bone strength reflects the integration of two main features : bone density and bone quality . while osteoporosis is frequently regarded as a women 's disease , up to two million men in the us alone suffer from the disease . a recent study showed that one in three osteoporotic fractures after the age of 50 occurs in men . more importantly , men have a higher mortality rate from hip fractures and a lower frequency of screening and treatment as compared to women [ 4 , 5 ] . as such , osteoporosis should be treated as a disease that affects both genders . although osteoporosis is an incurable disease , there are several steps that can be taken in order to control bone loss , including adequate calcium and vitamin d intake , regular physical exercise , and pharmacological treatment [ 6 , 7 ] . research in osteoporosis has paid considerable attention to the level of knowledge among women and its associations with health behaviors . for example , werner and colleagues found that women demonstrated a higher level of knowledge regarding the role of physical activity and calcium intake in the prevention of osteoporosis , but knew less about the role of genetics , caffeine intake , alcohol consumption , and smoking as risk factors . in addition , a higher level of knowledge was found to be associated with such health behaviors as greater calcium intake and regular performance of physical activities [ 812 ] . despite the fact that osteoporosis is a major health concern among men , little research attention has been paid to evaluating the associations between knowledge and health behaviors in this population . the limited number of studies among men shows that they demonstrate a low level of knowledge about the disease [ 1315 ] . to the best of the author 's knowledge , only one study has evaluated the correlations between the level of knowledge about osteoporosis and health behaviors among men . although no direct associations were found between these variables , it must be noted that only a small portion of the participants in this study and the other studies mentioned above were diagnosed as osteoporotic [ 15 , 16 ] . hence , the ability to generalize from their findings to the population of osteoporotic men is questionable . the aims of the current study were to evaluate the level of knowledge about osteoporosis among osteoporotic men and to assess the correlations with their health behaviors . a convenience sample of 100 osteoporotic men attending the bone and mineral clinic at a major medical center in israel was recruited in 2004 . the participants ' mean age was about 63 , the vast majority was married , and their level of education and income were relatively high . two types of health behaviors were assessed , namely , calcium intake and participation in physical activities . ( a ) calcium intakesimilar to other studies [ 8 , 17 ] , the participants ' calcium intake was measured by a self - report questionnaire on the number of glasses of milk , servings of yogurt , slices of hard cheese , and cups of white cheese consumed daily , as well as the type and amount of soy products and calcium supplements consumed . scores were calculated for calcium intake in milligrams , based on the information presented in the nih web site and adapted for israel . the content validity of the calcium intake measures was provided by two israeli experts in the field of osteoporosis . similar to other studies [ 8 , 17 ] , the participants ' calcium intake was measured by a self - report questionnaire on the number of glasses of milk , servings of yogurt , slices of hard cheese , and cups of white cheese consumed daily , as well as the type and amount of soy products and calcium supplements consumed . scores were calculated for calcium intake in milligrams , based on the information presented in the nih web site and adapted for israel . the content validity of the calcium intake measures was provided by two israeli experts in the field of osteoporosis . ( b ) physical activityparticipation in physical activity was assessed by asking whether participants regularly engaged in physical activities , which type of activities they engaged in ( e.g. , walking , swimming , weight - bearing exercises , and home exercises ) , the number of times a week , and for how many minutes each time . a total score of the number of minutes engaged in all physical activities was calculated . participation in physical activity was assessed by asking whether participants regularly engaged in physical activities , which type of activities they engaged in ( e.g. , walking , swimming , weight - bearing exercises , and home exercises ) , the number of times a week , and for how many minutes each time . a total score of the number of minutes engaged in all physical activities was calculated . participants ' knowledge about osteoporosis was assessed by an adapted version of the facts on osteoporosis quiz ( fooq ) . the original quiz consists of 24 true or false statements related to risk factors and preventive behaviors associated with osteoporosis . for this study , one item referring to african - american women was deleted and four statements regarding the incidence of fractures and risk factors related to men were added . similar to other studies [ 8 , 9 ] , a do n't know each item was coded as 0 for incorrect and do n't know responses or 1 for the correct answer . this information included gender , age , education level , income , and marital status . in addition , data were collected from the participants ' medical records regarding the number of previous fractures , time since the last fracture , and bone density scan scores . a computerized search of medical records was performed by the physician in order to locate men who had been treated for osteoporosis during the year preceding the study . a total of 115 patients were approached by the physician and presented with the aims of the study . a response rate of 87% was obtained , resulting in a final sample size of 100 participants . once the participants signed informed consent forms , they were contacted by the researcher and were interviewed on the phone using a structured questionnaire . all participants signed informed consent forms . in order to protect the participants ' privacy , the data obtained from their medical records and interviews were coded anonymously to a password - protected file . the statistical analysis included descriptive statistics ( means , standard deviations , percentages ) to describe the sample and the main study variables ( knowledge level , health behaviors , and background data ) . pearson 's correlations were calculated to assess the correlations between health behaviors , level of knowledge , and background data . table 2 presents the percentages of participants who correctly responded to the knowledge items , followed by the mean , median , and range scores for the overall index of knowledge . according to the median score , half of the men responded correctly to 66.6% of the statements in the overall index . the highest level of knowledge was found for the items related to the role of physical activities and calcium intake in preventing osteoporosis . however , participants showed lower knowledge for the items related to caffeine intake , alcohol consumption , and smoking as risk factors for osteoporosis . the lowest level of knowledge was found for the items related to the incidence of osteoporotic fractures in men and in regard to hypogonadism as a risk factor . table 3 presents the means of daily calcium intake and weekly participation in physical activities . as shown in the table , participants reported an average of 842 mg of daily calcium intake and an average of 120 minutes per week for engagement in physical activities . thirty percent of the participants reported that they do not engage in any kind of physical activity . of the 70% who did report on regular participation in physical activities , 52% reported on walking , 9% reported on swimming , 6% reported on weight - bearing exercises , and 3% reported on daily performance of home exercises . several statistically significant correlations were found between the participants ' sociodemographic / clinical characteristics , their level of knowledge , and their health behaviors . the participants ' level of knowledge about osteoporosis was positively correlated with education level and age ( r = .26 , p < .01 ; r = .21 , p < .05 , resp . ) and was negatively correlated with the number of fractures ( r = .19 , p < .05 ) . knowledge level and education were positively correlated with calcium intake ( r = .36 , p < .0001 ; r = .25 , p < .05 , resp . ) . knowledge level and age were positively correlated with participation in physical activities ( r = .47 , p < .0001 ; r = .24 , p < .05 , resp . ) . finally , the number of fractures was negatively correlated with participation in physical activities ( r = .31 , p < .001 ) . the current study had two main objectives : to evaluate the level of knowledge about osteoporosis in osteoporotic men and to assess its correlations with health behaviors . however , in comparison to other studies among men [ 13 , 15 ] , participants in the present study had a higher level of knowledge . this may be attributable to the fact that while other study samples were recruited from the general population and were largely not osteoporotic , the current sample was recruited from a bone and mineral disorders clinic and participants were diagnosed as osteoporotic . participants showed a high level of knowledge regarding the role of physical activities and calcium intake in preventing osteoporosis . this finding is encouraging , as these activities are major countermeasures against bone loss [ 6 , 7 ] . however , a lower level of knowledge was found regarding such behaviors as caffeine intake , alcohol consumption , and smoking , which are considered to be risk factors for osteoporosis . since alcohol consumption and smoking are attributed to masculine behaviors , the practical meaning of these findings is that health professionals should pay closer attention to mens ' knowledge about the effects of these behaviors on bone mass . the lowest level of knowledge was found in regard to the incidence of osteoporotic fractures in men . this finding is rather surprising , as it is reasonable to assume that osteoporotic patients would demonstrate a higher level of knowledge on this matter . the fact that only one - third of the participants had an osteoporotic fracture may serve as an explanation . regarding the second aim of the study , that is , to assess the correlations between the level of knowledge about osteoporosis and the health behaviors of osteoporotic men , the findings support those of studies among women [ 812 ] . indeed , a higher level of knowledge was correlated with higher participation in regular physical activities and calcium intake . however , the findings contradict those of doheny and colleagues showing no direct associations between knowledge level and health behaviors . a possible explanation for this contradiction may be related to the fact that doheny and colleagues included in their model other variables , such as health beliefs , which were more powerful predictors for these behaviors . furthermore , other studies showed that improving knowledge alone did not change behavior [ 2123 ] . since there is very limited data on these correlations among men , future studies should address this discrepancy by incorporating both knowledge and health beliefs assessments in their models . for instance , a positive correlation was found between the level of knowledge about osteoporosis and the level of education . as suggested in other studies [ 8 , 9 ] , greater access of highly educated patients to such information sources as professional journals and the internet may be related to their level of knowledge . higher age was found to be positively correlated with level of knowledge and participation in regular physical activities . the tendency towards later onset of osteoporosis in men may explain why older patients sought out more comprehensive knowledge and concentrated their efforts on engaging in more physical activities . in addition , a lower number of fractures were correlated both with a higher level of knowledge and higher participation in physical activities . the severe impact that osteoporotic fractures have on patients ' mobility and the major role that physical activities play in preserving bone mass may account for this finding . finally , the participants ' reported mean of 120 minutes of weekly engagement in physical activities is encouraging since it meets the recommended level of physical activity for maintaining bone health . however , only 6% of the participants reported on regular performance of weight - bearing exercises , which are specifically recommended for osteoporotic patients . this finding calls for health professionals to emphasize the contribution that this kind of activity makes to preserving bone mass . furthermore , the mean amount of calcium reported by the participants was substantially under the recommended 1200 mg for men over the age of 50 [ 2 , 26 ] . this finding is puzzling given that the participants demonstrated the highest level of knowledge on items related to calcium intake . a possible methodological explanation for this contradiction may be related to the self - report method that was used in the study . participants were asked to report on their intake of dairy products and calcium supplements during the week preceding the interview . it is possible that they simply underestimated the amount of products consumed and reported on lower calcium intake . as calcium intake is a major step towards protecting against bone mass deterioration , health professionals should emphasize the importance of adequate calcium intake for preserving bone mass . first , due to the use of a convenience sample , the results of the present study apply to this specific clinical setting and do not allow generalization to all osteoporotic patients in israel . second , the cross - sectional nature of the present study calls for caution when interpreting the findings . despite its limitations , this study makes an important contribution to expanding our knowledge about osteoporosis and the correlations between level of knowledge , performance of regular physical activities , and calcium intake among osteoporotic men . the findings stress the need for health professionals to consider using intervention programs to evaluate and improve the level of knowledge about osteoporosis , especially among less educated patients .

aims . the aims of the current study were to evaluate the level of knowledge about osteoporosis among osteoporotic men and to assess the correlations with their health behaviors . method . a convenience sample of 100 osteoporotic men ( mean age 63 ) attending the bone and mineral clinic at a major medical center in israel was recruited in 2004 . participants were interviewed by phone using an adapted version of the facts on osteoporosis quiz ( fooq ) . participants were also asked to report on their daily calcium intake and participation in physical activities . results . the overall level of knowledge about the disease demonstrated by the participants was moderate . higher education , older age , and fewer fractures were correlated with a higher level of knowledge . in addition , higher levels of education and knowledge were correlated with higher calcium intake . lastly , a higher knowledge level , older age , and fewer fractures were correlated with higher participation in physical activities . conclusions . given the correlations between health behaviors and the level of knowledge among osteoporotic men , intervention programs should be used to evaluate and improve knowledge about osteoporosis , especially among less educated patients .

one of the most serious drawbacks associated to einstein s theory of general relativity ( gr ) is the unavoidable existence , under reasonable physical assumptions , of spacetime singularities deep inside black holes , as well as in the early universe @xcite . this is due to the fact that at such singularities the predictability of physical laws comes to an end because measurements are no longer possible . the underlying reason is that the existence of incomplete geodesics implies the destruction / creation of observers and/or information ( light signals ) as some limiting boundaries are approached . as a way out of this problem , penrose introduced @xcite the cosmic censorship conjecture , by which singularities emerging out of gravitational collapse are assumed to be hidden behind an event horizon , so they can not causally affect physical processes taking place in the portion of universe accessible to far away observers . since sweeping the problem under the carpet does not solve it , finding a consistent description of the interaction between gravity and matter , where the resolution of spacetime singularities may be naturally achieved , has become a major goal from different perspectives ( classical and quantum , fundamental and phenomenological ) . it is typically argued that spacetime singularities should be resolved by a quantum theory of gravity . this is supported by the idea that the quantum degrees of freedom of the gravitational field are expected to be non - negligible in regions of very high curvature . this view , inherited from the effective field theory approach to quantum theory , is very appealing but should be taken with care in gravitational scenarios , where the notion of singularity is not necessarily tied to the divergence of some quantities in some regions @xcite . for geometric theories of gravity ( classical theories ) , the very existence of observers is more fundamental than the possibility of obtaining absurd results in a measurement , as the latter is not possible without the former . it is for this reason that the existence of incomplete geodesics , for which the affine parameter is not defined over the whole real line , appears as the key element in the singularity theorems . in the context of gr , the incompleteness of geodesics usually occurs simultaneously with the divergence of scalar quantities , such as the energy density of the matter sources or certain curvature invariants . these divergences appear as a _ reason _ for the incompleteness of the geodesics , leading to a _ rule of thumb _ for the identification of singular spacetimes @xcite ( see @xcite for a critical viewpoint on this issue ) . indeed this has shaped many approaches to the singularity problem based on the idea that such quantities should remain bounded ( see e.g. @xcite for a review ) . one of such approaches is given by classical non - linear models of the electromagnetic field . this is supported on the success of born - infeld theory of electrodynamics , where a square - root modification of the maxwell action gets rid of the divergence of the self - energy of coulomb s field by imposing a maximum bound on the electric field at the center @xcite . it is natural to wonder whether a similar mechanism for the removal of singularities could occur in the context of gravitation . in this sense born - infeld electrodynamics , though successful in making the energy density of the electromagnetic field finite , fails to keep at bay divergences on the curvature scalars when coupled to gravity , which comes alongside with the incompleteness of ( some ) geodesics @xcite . in this regard , similar attempts using other well defined non - linear electrodynamics models have failed as well @xcite . nonetheless , it is worth mentioning that some examples of non - linear electrodynamics do regularize curvature divergences @xcite , but such models are constructed in an ad hoc way and yield unphysical features , as shown by bronnikov @xcite ( see also @xcite ) . this strategy has been extended to the case of gravitational actions going beyond the einstein - hilbert lagrangian of gr , such as gauss - bonnet and , more generally , lovelock theories @xcite , where similar disappointing results have been obtained ( see e.g. @xcite for some attempts in this context ) . consequently , it is fair to say that such models have been unable to find a fully consistent way out of the singularity problem in gr . in this work we shall examine in detail the relation between energy density , curvature invariants , and geodesic completeness in some theories of gravity beyond gr . this will allow us to see if the correlations observed in gr among those quantities still persist in other gravitational theories ( see @xcite for related ideas explored in this context ) . in other words , can matter / curvature infinities be seen as the _ reason _ for the incompleteness of geodesics ? this study is relevant in order to understand what problems , if any , a quantum version of those theories of gravity should solve . in our approach , we interpret gravitation as a geometric phenomenon , but geometry as something more than just curvature . in the metric - affine ( or palatini ) formulation of classical gravitation , geometric properties such as non - metricity and torsion , besides curvature , are allowed by construction . the lack of these freedoms in the usual riemannian approach could be an excessive constraint with a potentially non - negligible impact on the problems that gravity theories typically exhibit at high - energy . it should be noted that non - metricity and torsion are necessary to deal with different kinds of geometric defects in continuum systems with a microstructure , such as bravais crystals or graphene @xcite . for this reason , metric - affine geometry is commonly used in the study of condensed matter physics @xcite . nonetheless , for operational convenience , in this work we shall neglect torsion ( see , however , @xcite for a discussion on the role of torsion in metric - affine theories ) and focus on non - metricity only @xcite . indeed , the question of whether gravity as a manifestation of the curvature of spacetime is purely a matter of metrics or if the affine structure of spacetime is on equal footing as the metric one has been at debate since soon after the establishment of gr ( see e.g. @xcite for a pedagogical discussion ) . certainly , when gr is formulated la palatini , the variation of the action with respect to the independent connection yields a set of equations that simply express the metric - connection compatibility condition . the fact that this approach yields the same dynamics as that of considering the metric as the only independent degree of freedom ( _ metric _ approach ) has frequently lead to regard the palatini variation as merely an alternative way to deriving the field equations of gr . for other theories of gravity , however , the compatibility between metric and connection is broken and the peculiarities of the metric - affine approach become manifest . the scenario considered here corresponds to a simple quadratic @xmath0 gravity extension of gr ( for which many applications have been investigated in the literature , see e.g. @xcite ) , formulated in a metric - affine framework . it should be pointed out that with the advent of the gravitational wave astronomy following the discovery of gw150914 by ligo @xcite , both gravitational extensions of gr and exotic compact objects in such models can be put to experimental test @xcite . as the matter sector , in our setup we consider an anisotropic fluid ( constrained to satisfy standard energy conditions ) , which has been recently investigated in some detail in a number of astrophysical / cosmological scenarios @xcite . such fluids include a number of particularly interesting cases , such as that of non - linear electrodynamics . the resulting spacetimes are split into four different cases , depending on the combinations of the signs of the coupling constant of the quadratic gravity contribution and of a constant associated to the matter sector . a noteworthy feature of many of the solutions obtained is the emergence of a finite - size wormhole structure [ see @xcite for detailed account on wormhole physics ] replacing the point - like singularity typically found at the center of gr black holes . it is worth pointing out that wormholes have been suggested as solutions to spacetime singularities in approaches to quantum gravity such as loop quantum gravity @xcite and shape dynamics @xcite ( see also @xcite and references therein , where wormholes are linked to regularization mechanisms . ) the main aim of the present work is to determine when the typically assumed correlation between divergence of curvature scalars and geodesic incompleteness is broken . in this sense , we note that the concept underlying the formulation of the singularity theorems @xcite is that of geodesic completeness , namely , whether a geodesic curve can be extended to arbitrarily large values of its affine parameter or not . this is a logically independent and more primitive concept than that of curvature divergences [ see @xcite for a nice discussion on this issue ] , with the latter playing no role on such theorems . as already mentioned , the widespread identification between them in the literature is explained as due to the fact that in many cases of interest ( particularly in gr ) those spacetimes having ( some ) incomplete geodesics , also yield ( some ) divergent curvature scalars @xcite . in some of the spacetimes found here we explicitly show that the presence of wormholes yield geodesically complete spacetimes , though curvature scalars may blow up at the wormhole throat . in other cases without wormholes , we meet the incompleteness of geodesics despite the finiteness of curvature scalars . the relation of these magnitudes with the ( boundedness of the ) energy density of the matter fields is also discussed . the paper is organized as follows : in sec . [ sec : ii ] we introduce the action and main equations of @xmath0 gravity formulated la palatini . in sec . [ sec : iii ] we specify the matter sector of our theory under the form of an anisotropic fluid and introduce a number of constraints on it . next , in sec . [ sec : iv ] , we focus our discussion upon a quadratic @xmath0 model and solve the field equations for the metric . sec . [ sec : v ] contains the main results of this work , where we study the four different classes of spacetimes , and discuss in detail the relation between energy density , curvature scalars , and geodesic completeness . we conclude in sec . [ sec : vi ] with a summary and some perspectives . the action of @xmath0 gravity can be written as @xmath1 with the following definitions and conventions : @xmath2 is newton s constant in suitable units ( in gr , @xmath3 ) , @xmath4 is the determinant of the spacetime metric @xmath5 , @xmath0 is a given function of the curvature scalar , @xmath6 , where the ricci tensor , @xmath7 , which follows from the riemann tensor as @xmath8 , is entirely built out of the affine connection , @xmath9 , which is a priori independent of the metric ( metric - affine or palatini approach ) . finally , @xmath10 is the matter action , which is assumed to depend only on the matter fields , collectively denoted as @xmath11 , and on the metric @xmath5 . performing independent variations of the action ( [ eq : action ] ) with respect to metric and connection one gets two systems of equations @xmath12 where @xmath13 and @xmath14 is the stress - energy tensor of the matter . it is worth mentioning that eq . ( [ eq : connection ] ) simply states that the independent connection fails to be metric or , in other words , that a non - metricity tensor @xmath15 is present . in the gr case , @xmath16 and eq . ( [ eq : connection ] ) becomes @xmath17 , which is fully equivalent to @xmath18 and thus @xmath19 becomes the levi - civita connection of the metric @xmath5 , while the field equations ( [ eq : metric ] ) boil down to those of gr with possibly a cosmological constant term . this is the underlying reason for the equivalence between the palatini and metric formulations of gr . for more general @xmath0 lagrangians , however , non - metricity becomes an inherent feature of the field equations . it is also important to understand the intimate relation existing between matter and gravity in palatini theories of gravity . tracing with @xmath20 in eq . ( [ eq : metric ] ) yields the result @xmath21 where @xmath22 is the trace of the stress - energy tensor . this is not a differential equation , but instead it just establishes an algebraic , non - linear relation between curvature and matter . given an @xmath0 theory , solving eq . ( [ eq : trace ] ) yields a solution @xmath23 , which generalizes the gr relation , @xmath24 . this algebraic relation explains the absence of extra dynamical degrees of freedom in our theory as compared to the usual metric approach , where the scalar curvature satisfies a second - order differential equation , thus implying the presence of propagating scalar degrees of freedom . in the palatini case , the additional curvature terms are just nonlinear functions of @xmath22 and can be collected as extra pieces in an effective stress - energy tensor . this way , the palatini field equations for the metric ( [ eq : metric ] ) can be simply written as @xmath25 where the _ effective _ stress - energy tensor is written as @xmath26\nonumber\\ & + & \frac{1}{f_r}\left[\nabla_\mu \nabla_\nu f_r - g_{\mu\nu}\box f_r\right ] \ .\end{aligned}\ ] ] however , from a practical point of view , in many cases of interest it is easier to solve the field equations by noting that the result @xmath23 allows us to introduce in eq . ( [ eq : connection ] ) a rank - two tensor @xmath27 satisfying @xmath28 such that the independent connection @xmath19 can be expressed as the christoffel symbols of the metric @xmath27 , i.e. , @xmath29 \ .\ ] ] comparing this with eq . ( [ eq : connection ] ) , it is immediately seen that the physical metric @xmath5 can be obtained out of @xmath27 according to the conformal transformations @xmath30 where , recall , @xmath31 is a function of the matter , @xmath32 . an alternative representation of the field equations is now possible in terms of @xmath27 by contracting eq . ( [ eq : metric ] ) with @xmath33 and using the relations ( [ eq : conformal ] ) to obtain @xmath34 where @xmath35 is the ricci tensor constructed with the christoffel symbols of the metric @xmath27 , see eq . ( [ eq : lcfr ] ) . note that due to the fact that @xmath36 all the objects on the right - hand - side of eq . ( [ eq : fieldh ] ) are just functions of the matter . thus eq . ( [ eq : fieldh ] ) represents a set of second - order field equations for @xmath27 and , since the conformal transformations ( [ eq : conformal ] ) depend only on the matter sources , the field equations for @xmath5 will be second - order as well . in vacuum , @xmath37 , one has @xmath38 ( up to a trivial re - scaling of units ) and the field equations ( [ eq : fieldh ] ) reduce to those of gr with a cosmological constant term , which confirms the absence of ghost - like propagating degrees of freedom in these theories . in this work we are interested on obtaining black hole solutions in palatini @xmath0 theories , and to compare their structure with that of electrically charged black holes of gr . however , due to the fact that the non - linear corrections appearing on the right - hand - side of the new gravitational field equations ( either in eq . ( [ eq : grlike ] ) or eq . ( [ eq : fieldh ] ) ) depend just on the trace of the matter , @xmath39 , the new dynamics encoded in palatini @xmath0 theories can only be excited when non - traceless stress - energy tensors are considered . this implies that considering a classical maxwell electromagnetic field , whose trace is zero , would yield electrovacuum solutions identical to those of gr with a cosmological constant ( reissner - nordstrm - anti - de sitter black holes ) . thus , in order to explore new physics in these scenarios , we must consider stress - energy tensors with a non - vanishing trace . one can then assume that a trace anomaly or other types of corrections are generated by quantum effects and propose a stress - energy tensor of the following form : @xmath40 this corresponds to an anisotropic fluid , where @xmath41 is the energy density and @xmath42 are the ( different , in principle ) pressures . this class of fluids has been recently considered in refs . @xcite where , working in slightly different scenarios , it was found that wormhole solutions can be constructed in eddington - inspired born - infeld theories of gravity without violation of the energy conditions . in contrast to that approach , as we shall show below , in the palatini @xmath0 scenario considered here , wormholes can be obtained directly as solutions of the field equations without _ a priori _ designer approach . to simplify the analysis and obtain analytically accessible scenarios , let us constrain the functions defining our model . first we restrict the fluid to satisfy @xmath43 and @xmath44 , where @xmath45 is a free input function whose form will be specified later . thus , the stress - energy tensor for this fluid reads @xmath46 \ .\ ] ] a motivation for considering these constraints is the fact that the form of the stress - energy tensor ( [ eq : sef ] ) exactly matches that of some non - linear theories of electrodynamics . indeed , in such a case , defining the matter model as a given function @xmath47 of the two field invariants @xmath48 and @xmath49 , that can be built out of the field strength tensor @xmath50 and its dual @xmath51 , the corresponding stress - energy tensor is written as @xmath52 \ , \ ] ] where @xmath53 and @xmath54 . identifying @xmath55 and @xmath56 , it is clear that specifying a function @xmath45 allows to solve these equations to determine the function @xmath47 , at least in implicit form , associated to the anisotropic fluid under consideration . to obtain additional information on the fluid described by the stress - energy tensor ( [ eq : sef ] ) , using the fact that the independent connection @xmath19 does not couple to the matter in the action ( [ eq : action ] ) , one finds that the standard conservation equation , @xmath57 , holds in these theories . now , considering static spherically symmetric spacetimes , we can write a line element for the spacetime metric @xmath5 as @xmath58 where the functions @xmath59 , @xmath60 and @xmath61 are to be determined by integration of the gravitational field equations . with this line element , the conservation equation above just reads @xmath62r_x / r=0 $ ] , where @xmath63 and @xmath64 , which can be integrated to give a relation between @xmath61 and @xmath65 as @xmath66 \ , \ ] ] where @xmath67 is an integration constant with dimensions of length and @xmath68 is the energy density without dimensions . to proceed further and integrate explicitly this equation , we need to specify a function @xmath45 . let us take the choice @xmath69 where , for dimensional consistency , @xmath70 is a dimensionless constant and @xmath71 has dimensions of inverse density . this choice covers a number of interesting cases and allows us to obtain analytical solutions . indeed , in this case , from the expression ( [ eq : kchoice ] ) , the relation between @xmath65 and @xmath61 in eq . ( [ eq : rrho ] ) is explicitly written as @xmath72 where @xmath73 is a reference energy density that arises as an integration constant and can be fixed from the asymptotic behavior of the fluid . in particular , for @xmath74 , the fluid density and the metric far from the center tend to those generated by a maxwell field , namely , @xmath75 , which allows to relate @xmath76 with the electric charge , @xmath77 . moreover , if @xmath78 , the stress - energy tensor of the fluid exactly becomes that of a maxwell field with a vanishing trace and , as already mentioned , this yields the same dynamics as that of gr . however , non - trivial combinations of @xmath70 and @xmath71 provide modified field equations and generate new solutions . the analysis now requires to be split into the cases @xmath79 and @xmath80 , since their properties are very different . for @xmath81 there is a critical radius @xmath82 } r_0 $ ] at which the energy density blows up . thus the location of the standard divergence in the density of the fluid ( maxwell case ) shifts from @xmath83 to the finite radius @xmath84 . on the other hand , for the case @xmath79 the energy density is finite everywhere , having a maximum value @xmath85 at the center . this is quite a similar result as that found in certain models of non - linear electrodynamics , such as the one of born and infeld @xcite , where the electric field attains a maximum value at the center and regularizes the energy density . in sec.[sec : v ] we will study the implications and impact of the finiteness ( or not ) of the energy density , via the bound ( [ eq : bound ] ) , on the regularity of the corresponding spacetimes . note in this sense that the particular case with @xmath78 and @xmath86 was studied in detail in ref.@xcite . to simplify the analysis and the notation let us fix @xmath74 from now on and define @xmath87 , with @xmath88 denoting the sign of @xmath71 , and introduce the dimensionless variable @xmath89 , with @xmath84 the critical radius defined above . then , we get @xmath90 so that the energy density of the fluid simply reads @xmath91 to conclude this section , we emphasize that we are only considering matter sources satisfying the energy conditions . for instance , the weak energy condition ( wec ) states that the following conditions have to be fulfilled @xcite : @xmath92 and @xmath93 ( @xmath94 ) in eq . ( [ eq : tani ] ) . for the particular ansatz ( [ eq : sef ] ) with the choice ( [ eq : kchoice ] ) and the expressions for the energy density ( [ eq : ed1 ] ) and ( [ eq : bound ] ) , it follows that the wec will be satisfied whenever @xmath95 , which is consistent with the choice @xmath74 above . to work with the simplest possible scenario , let us consider the quadratic @xmath0 model @xmath96 where @xmath97 is a constant with dimensions of length squared . this model is particularly amenable for calculations because the trace equation ( [ eq : trace ] ) yields @xmath24 , which is the same linear relation as in gr , this result being just an accident related to the functional form of the quadratic model in four dimensions . with this choice , we find that the quantity @xmath31 , which will play a key role in the characterization of the solutions , takes the simple form to take positive and negative values , then @xmath98 should be parameterized as @xmath99 . this leads to four types of models depending on the different combinations of @xmath100 and @xmath101 . ] @xmath102 where @xmath103 ( and we have introduced @xmath104 to denote the energy scale associated to the gravitational coupling constant @xmath105 ) represents the relative strength between the matter and gravitational sectors , such that the gr limit is recovered when @xmath106 . note that the parametrization of @xmath97 with @xmath107 and of @xmath71 with @xmath108 leads to four different configurations , which will be studied separately in sec.[sec : v ] . to solve the field equations ( [ eq : fieldh ] ) we introduce a static , spherically symmetric line element for the auxiliary metric @xmath27 as @xmath109 where @xmath110 and @xmath111 are two functions to be determined using the field equations ( [ eq : fieldh ] ) . from the symmetry @xmath112 one finds that @xmath113 , which implies that @xmath114 constant , which can be put to zero by a redefinition of the time coordinate without loss of generality . the remaining field equation follows from the component @xmath115 which can be simplified by introducing the mass ansatz @xmath116 leading to the first - order equation @xmath117 where @xmath118 . to handle the integration of the mass function @xmath119 it is useful to take a parametrization @xmath120 with @xmath121 representing the schwarzschild radius and @xmath122 a dimensionless constant defined as @xmath123 this puts forward that @xmath119 is made out of a constant contribution , @xmath124 , plus a term generated by the fluid and represented by the function @xmath125 ( see eq . ( [ eq : gzfr ] ) below ) . the resulting solution allows to construct the physical metric @xmath5 by means of the conformal relations ( [ eq : conformal ] ) . this way , the physical line element can be written as @xmath126 taking now into account that such conformal transformations also imply that @xmath127 whose dimensionless version using @xmath128 and @xmath129 is @xmath130 and then we obtain the relation @xmath131 } \ , \label{eq : dzdx}\ ] ] which allows us to express ( [ eq : thth ] ) , by means of eq . ( [ eq : mz ] ) , as a differential equation involving only the variable @xmath128 : @xmath132 with @xmath133 . therefore , by formally integrating @xmath134 , the metric component @xmath135 in eq . ( [ eq : lineel ] ) is obtained in terms of the radial function @xmath128 as @xmath136 the non - trivial modified dynamics induced by the gravitational @xmath137 corrections necessarily modifies the geodesic structure of the corresponding geometry as compared to gr solution . this is a question of utmost interest , given the fact that geodesic completeness , namely , whether any ( null and timelike ) geodesic can be extended to arbitrarily large values of the affine parameter , is the most fundamental and generally accepted criterion to determine whether a spacetime is singular o not @xcite . since timelike geodesics are associated to physical observers and null geodesics to the propagation of information , this criterion captures the intuitive idea that in a physically well behaved spacetime _ nothing can suddenly cease to exist _ and that _ nothing can emerge out of nowhere_. nonetheless , as discussed in the introduction , there is frequently a misunderstanding in the literature , taking curvature divergences as an equivalent concept to that of geodesic completeness in order to detect the presence of spacetime singularities . as we shall show in sec.[sec : v ] , such an identification explicitly breaks in many of the geometries considered in this work . thus we are mainly interested in studying the geodesic structure in those cases where the gr geodesics are incomplete and consequently yield a singularity , regardless of the presence or not of curvature divergences . to this end , in this section we shall specify the geodesic equation for palatini @xmath0 theories and solutions of the form studied here . in a coordinate system , a geodesic curve @xmath138 associated to a given connection @xmath139 is defined by the equation @xcite @xmath140 where @xmath141 is the affine parameter . since in the action ( [ eq : action ] ) defining our model , the matter part couples to the metric but not to the connection , we will focus on the geodesics associated to the physical metric @xmath5 , which are the ones that the matter fields follow according to the einstein equivalence principle ( see @xcite for an extended discussion on geodesics in metric - affine spaces ) . the analysis can be largely simplified by writing the geodesic equation using the tangent vector @xmath142 , which satisfies @xmath143 , with @xmath144 corresponding to spacelike , null , and timelike geodesics , respectively . taking advantage of spherical symmetry , without loss of generality we can rotate the angular plane in such a way that it coincides with @xmath145 , which further simplifies the problem . from the line element ( [ eq : lineel ] ) we can , in addition , identify two conserved quantities of motion , @xmath146 and @xmath147 . for timelike geodesics , these quantities carry the meaning of the total energy per unit mass and angular momentum per unit mass , respectively . for null geodesics @xmath148 and @xmath149 lack a proper meaning by themselves , but the quantity @xmath150 can be identified as an apparent impact parameter as seen from the asymptotically flat infinity @xcite . under these conditions , the geodesic equation ( [ eq : geodesics ] ) for the above geometries simply reads @xmath151 by using the relation of coordinates ( [ eq : tildexz ] ) ( and also the associated eq . ( [ eq : dzdx ] ) ) , we rewrite the geodesic equation ( [ eq : geofr ] ) as @xmath152 where @xmath141 is measured in units of @xmath84 , and the sign @xmath153 corresponds to outgoing / ingoing geodesics , with @xmath154 as one can deduce by following the steps of sec . [ subsec : sol ] . equivalently , the geodesic equation can be written in the more convenient form @xmath155 in the next section we shall study in detail the properties of the four different cases of configurations , corresponding to the combinations of the signs of @xmath97 and @xmath71 , and their respective features regarding the behaviour of the energy density , the curvature scalars , and geodesic completeness . let us now particularize the above equations to the case in which @xmath157 and @xmath158 , for which we obtain @xmath159 the function @xmath160 determined by eq . ( [ eq : gzfrmp ] ) can be easily solved using power series expansions , and the resulting solutions can be classified in terms of the values of the parameter @xmath98 defined in eq . ( [ eq : fz ] ) . depending on whether @xmath98 is greater or smaller than unity , one finds different families of solutions . in this sense , the behavior of the function @xmath161 , which arises from the resolution of eq . ( [ eq : tildexz ] ) , contains valuable information . note that according to eq . ( [ eq : fzm ] ) the function @xmath162 vanishes at @xmath163 which sets a critical value for @xmath164 . when @xmath165 , the radial function @xmath166 has a minimum at @xmath167 where , according to eq . ( [ eq : tildexz ] ) , @xmath168 . ( from now on , we drop the tilde from @xmath169 to lighten the notation ) . though a compact expression for @xmath170 is not easy to find in general , a series expansion around @xmath171 yields the result @xmath172 , which shows that for @xmath173 the area of the @xmath174-spheres decreases with decreasing @xmath175 , but for @xmath176 increases with decreasing @xmath175 , with a minimum at @xmath177 ( @xmath171 ) . this behavior is clearly seen in fig . [ fig:1 ] where eq . ( [ eq : tildexz ] ) has been inverted numerically for several values of @xmath178 . the interpretation of this minimal area in the two - spheres is well known in the literature : it represents a wormhole @xcite , a topologically non - trivial bridge connecting two asymptotically flat spacetime regions , where @xmath179 ( @xmath177 ) sets the location of the throat . as it has been found in other cases of palatini @xmath0 theories coupled to various matter sources @xcite , the emergence of this structure is directly related to the existence of zeros in the function @xmath31 . as a function of the radial coordinate @xmath175 ( in units of @xmath180 ) , for @xmath181 ( solid , red ) , @xmath182 ( dashed , orange ) and @xmath183 ( dotted , green ) . note that far from the bouncing region ( @xmath171 , @xmath177 ) , where the wormhole throat is located , we have @xmath184 , which restores the gr behavior there.,scaledwidth=45.0% ] to study in more detail the geometry around @xmath179 , it is useful to consider the following expansions @xmath185 \ , \label{eq : frg } \\ g_z&\approx & \frac{c}{(z - z_c)^{3/2 } } + \mathcal{o}[(z - z_c)^{-1/2}]\ , \label{eq : gzg}\end{aligned}\ ] ] where @xmath186^{3/2}}$ ] is a constant . upon integration , one finds that @xmath187\ , \label{eq : gg}\ ] ] which diverges at @xmath171 . the @xmath135 component of the physical metric appearing in eq . ( [ eq : gttz ] ) can thus be approximated as @xmath188\ . \label{eq : gttwh}\ ] ] due to the divergence in this metric component , curvature scalars generically diverge near @xmath171 . obviously , this behavior is shared by all those models in which the function @xmath31 has a single pole at @xmath171 . it should be noted , however , that curvature divergences are not synonyms with spacetime singularities , as mentioned in the introduction ( see sec.[sec : geocom ] below ) . now , let us analyze the case @xmath189 for which @xmath179 in ( [ eq : zc ] ) has no real solutions . in this case , @xmath128 belongs to the range @xmath190 and no wormhole geometries are found . near the center , @xmath191 , the relation ( [ eq : tildexz ] ) can be expanded as @xmath192 while @xmath31 becomes there @xmath193 and the function @xmath194 is finite @xmath195 in this case , near the origin @xmath160 can be approximated as @xmath196 where @xmath197 is a constant ( different for each value of @xmath98 ) whose value guarantees that the reissner - nordstrm solution of gr is recovered in the far limit , @xmath198 . the expansion of the metric component @xmath135 around the center is @xmath199 note that for the choice @xmath200 , the metric is finite everywhere . on the other hand , for @xmath201 the metric at the center is divergent and timelike , while for @xmath202 it becomes spacelike . nonetheless , no matter the behaviour of the metric at the center , in all cases curvature invariants such as @xmath203 do always have divergences at @xmath191 . the behaviour of the metric at the center also determines the number ( and type ) of the horizons , mimicking the basic description of some models of nonlinear electrodynamics @xcite : two , one ( degenerate ) or no horizons for @xmath201 ; a single non - degenerate horizon if @xmath202 , and no horizons if @xmath200 . finally , the critical case @xmath164 must be treated separately , leading to @xmath204 thus the metric diverges at @xmath191 , which induces the presence of curvature divergences there . whether a wormhole exists in this case or not is a matter of taste , as its throat would have vanishing area : @xmath205 to summarize the results obtained so far , we can say that when the matter density scale @xmath206 is larger than the gravity scale @xmath207 , i.e. , @xmath208 , the theory yields wormhole solutions . whether this wormhole is hidden behind an event horizon or not depends on the combination of parameters @xmath209 characterizing the solutions . however , a detailed analysis of the horizon structure of these solutions is beyond the purpose of the present work . we just mention that the geometry is almost identical to the reissner - nordstrm solution of gr everywhere except in the region within the inner horizon , and for arbitrary @xmath98 , we have @xmath210 , so that @xmath211 ( we explicitly reintroduce the tilde here ) and the role of @xmath128 as the radial coordinate in gr is restored , while the function @xmath160 in eq . ( [ eq : gzfr ] ) quickly converges to the gr solution , @xmath212 , thus recovering the reissner - nordstrm geometry of gr . ] , where some departures arise and modify the structure of horizons . when the matter density scale @xmath206 is lower than the gravity scale @xmath207 , the wormhole throat closes @xmath164 and no wormhole solution exist anymore @xmath213 . let us begin by noting that regardless of the value of @xmath98 , far from the center ( @xmath214 ) , @xmath215 and @xmath216 . this means that in that region the gr solution is recovered and the geodesics are essentially coincident with those of gr there . one can verify numerically that this approximation is valid ( almost exact ! ) for all configurations with @xmath217 and arbitrary @xmath122 . let us focus first on the wormhole configurations , @xmath178 , for which our main concern is to study the deviations in the behavior of geodesics near the throat , located at @xmath171 . consider first radial null geodesics ( @xmath218 ) . near the wormhole throat @xmath219 the geodesic equation ( [ eq : geozgtt ] ) becomes @xmath220 where @xmath221 . by direct integration , we find @xmath222 from this expression it follows that as @xmath219 one has @xmath223 . stated in words , this means that ingoing light rays , emitted from @xmath214 when @xmath224 , approach the wormhole at @xmath219 as @xmath225 , while outgoing light rays , which propagate to @xmath214 as @xmath226 , set off from the wormhole at @xmath219 and @xmath224 . a complete representation of the radial null geodesics is shown in fig . [ fig:2 ] . from this plot one verifies that the far limit recovers the gr behavior while near the throat the affine parameter diverges , guaranteeing in this way the completeness of these geodesics , in agreement with the analysis of the asymptotic behaviors provided above . ( measured in units of @xmath84 ) for radial null geodesics ( with @xmath227 ) , in the gr case ( @xmath228 , dashed ) and three @xmath178 cases ( @xmath229 , solid ) , for ingoing / outgoing trajectories . far from @xmath230 ( where the wormhole throat is located ) all curves converge to the gr solution @xmath231 , while for @xmath230 , the curves @xmath232 ( for @xmath178 ) diverge to @xmath233 which means that they are complete , as opposed to the gr case . , scaledwidth=45.0% ] let us now consider nonradial geodesics ( @xmath234 ) and/or timelike geodesics ( @xmath235 ) . since the left - hand side of ( [ eq : geofr ] ) is positive by construction , physical trajectories must preserve the positivity of the right - hand side . from the expansions ( [ eq : frg ] ) and ( [ eq : gg ] ) it follows that @xmath236 \ , \ ] ] which diverges to @xmath237 as @xmath238 . as a result , the right - hand side must vanish at some @xmath239 , forcing in this way the bounce of these curves and preventing them from reaching the wormhole throat . this is analogous to the behavior observed in the reissner - nordstrm solution of gr , where all such geodesics meet an infinite potential barrier generated by the central object @xcite and never reach the central singularity . we thus conclude that all null and timelike geodesics are complete in this wormhole spacetime . ] . let us recall that at the wormhole throat , @xmath171 , curvature divergences arise . however , due to the fact that radial null geodesics take an infinite affine time to reach the throat , this implies that they lie at the boundary of the spacetime and do not belong to the physically accessible region . this way such divergences have no influence upon physical observers and there is no need to invoke any cosmic censorship conjecture or similar arguments to hide such configurations behind an event horizon . since the wormhole throat can not be causally reached in finite affine time , these results put forward the existence of explicit examples where the presence of curvature divergences do not unavoidably entail singular solutions . let us now consider those cases with @xmath240 for which no wormhole structure was found . from eqs . ( [ eq : frnowh ] ) and ( [ eq : gnowh ] ) , we obtain for @xmath241 that @xmath242 the full discussion of the geodesic structure would proceed now in much the same way as in the case of certain models of non - linear electrodynamics coupled to gr , where the nature of the central region ( spacelike or timelike ) , which depends on the ratio @xmath243 , will determine the type of geodesic able to approach the innermost region . nonetheless , it is enough to consider radial null geodesics , for which the geodesic equation ( [ eq : geoz ] ) reads @xmath244 this equation can be readily integrated , @xmath245 , implying that the origin can be reached in a finite affine time , without possibility of further extension . this result is identical to that found in the gr case , which is regarded as singular , but is in sharp contrast with the previous results for the wormhole case . finally , for the transition case @xmath246 ( with @xmath247 ) , the expansion of the metric as @xmath241 yields @xmath248 radial null geodesics satisfy the following equation @xmath249 and one can easily find that @xmath250 , which puts forward that these geodesics are complete , as they take an infinite affine time to reach the center . however , this model hides an unusual complexity ( see fig . [ fig : geodesicsgamma1 ] ) . indeed , if one considers nonradial and/or timelike geodesics , configurations with @xmath251 lead to a bounce at some @xmath252 , while for those with @xmath253 geodesics take a finite affine time to reach the origin . thus , despite the completeness of radial null geodesics and of those with @xmath251 , the case @xmath164 may lead to geodesically incomplete configurations , depending on the values of the parameters . as a function of the radial coordinate @xmath128 ( in units of @xmath180 ) , for @xmath164 . the dashed curves represent radial null geodesics in gr , while the solid ones are those of our gravity model . the upper / lower curve is the ingoing / outgoing light ray . radial timelike geodesics with @xmath253 ( black dotted curves ) lie within the light cone and hit the origin in a finite affine time.,scaledwidth=45.0% ] let us now shift our attention to the case in which both @xmath107 and @xmath100 are positive . then we find @xmath254 an important difference as compared to the previous case is that , regardless of the value of @xmath98 , @xmath31 and @xmath194 diverge as @xmath255 , where the energy density @xmath41 becomes infinite . whether these divergences imply that the spacetime is singular or not is something nontrivial which must be determined after a careful scrutiny of the geometry and its geodesic structure . but before getting into that , one should note that the relation between the coordinates @xmath175 and @xmath128 , determined by @xmath256 , now is not monotonic , having a minimum as shown in fig . [ fig : minimum ] . as a function of the radial coordinate @xmath128 ( in units of @xmath180 ) , for @xmath164 ( solid , red ) . the curve @xmath257 ( dashed ) is shown for comparison . we identify two regions where @xmath258 is monotonic : one which tends to the gr solution @xmath257 and has a minimum , and another one close to the origin representing a non asymptotically flat solution which may be disconnected from the exterior one.,scaledwidth=45.0% ] unlike in the @xmath79 case , now the minimum is in the function @xmath259 rather than in @xmath166 . this puts forward that now it is the auxiliary geometry which is of the wormhole type . this minimum represents the throat of the wormhole and its location is given by @xmath260 , where @xmath261 is related to @xmath98 via @xmath262 . it should be noted that this wormhole is not symmetric , having an asymptotically minkowskian region as @xmath263 and a non flat region as @xmath264 when @xmath255 . in fact , as @xmath255 in the internal region , @xmath265 and @xmath266 imply that @xmath267 $ ] , which leads to @xmath268 using this relation and noting that as @xmath255 we have @xmath269 , one gets @xmath270 which is timelike and divergent as @xmath264 ( @xmath255 ) . the physical metric , on the other hand , has a completely different behavior . given that @xmath271 , and that @xmath272 , expanding about @xmath255 yields @xmath273 which are always finite at @xmath274 where , recall , the energy density diverges . in fig . [ fig : metricsp ] the behavior of the @xmath135 component is shown for a configuration which exhibits up to four horizons in the @xmath275 interval . in the @xmath276 case , as a function of the radial coordinate @xmath128 , for @xmath277 , @xmath278 and @xmath279 ( solid curve ) . the dotted line represents the gr solution with the same parameters . note that @xmath135 cuts 4 times the @xmath280axis , which implies @xmath281 horizons . the two external horizons are almost coincident with the gr prediction . the other two are a result of the modified dynamics . the vertical grey line represents the location where @xmath258 reaches its minimum , which is ( close but ) unrelated to the minima of @xmath135 . note that the horizontal axis begins at @xmath274.,scaledwidth=45.0% ] in the @xmath276 case , corresponding to radially ( @xmath282 ) infalling geodesics with @xmath283 in the geometry of fig . [ fig : metricsp ] ( solid curves ) as compared to their gr counterparts ( dashed curves ) . the upper pair represents null geodesics while the lower one is timelike . deviations from gr ( dashed curve ) only arise near @xmath261 . in gr timelike observers bounce before reaching the center , while light rays get there in a finite affine time . in the quadratic @xmath0 theory , both null and timelike geodesics reach the surface @xmath274 in a finite affine time . the vertical grid line represents the location where @xmath258 reaches its minimum , which sets a saddle point for @xmath232 . note that the horizontal axis begins at @xmath274.,scaledwidth=45.0% ] by proceeding in the same way as in the previous case , we now perform the analysis of the geodesic structure . in this sense , [ fig : affinesp ] puts forward that a region of infinite energy density is reached by null and timelike radial geodesics in a finite affine time . if the divergence in the matter sector is interpreted as defining a limiting boundary of the physical spacetime , where the equations no longer make sense , then the fact that geodesics can reach it in a finite affine time would imply that this geometry is singular . from the numerical results shown in figs . [ fig : metricsp ] and [ fig : affinesp ] and , from the above analytical approximations , it is evident that nothing special happens to the physical metric at the points @xmath274 or @xmath284 . this can be further emphasized by looking at the whole line element in the @xmath255 region , whose form is @xmath285 using this line element , one readily verifies that all curvature invariants are finite at @xmath274 despite the energy density being divergent at that point . though this divergence in the matter sector must be seen as a breakdown in the description of the fluid model considered , it serves to illustrate that divergences in the matter sector do not necessarily imply divergent curvature invariants . at the same time , the finiteness of curvature invariants is unrelated to the completeness of geodesics . the fact that the energy density diverges at @xmath274 and that it changes sign in the @xmath286 region somehow suggests that the physical region should be restricted to the open interval @xmath287 . given that both null and timelike radial geodesics reach the @xmath274 surface in a finite affine time , if one wants to have a nonsingular spacetime , an artificial wormhole extension attached at @xmath274 should be considered to complete the geodesics . this construction , though mathematically admissible , seems a bit unnatural as compared to the wormhole solutions found in the @xmath288 case , where the energy density is always finite . extended into the @xmath286 region for the same parameters as in fig . [ fig : metricsp ] . the geometry now exhibits up to @xmath289 horizons . the metric diverges as @xmath290 as @xmath291 ( schwarzschild like ) . note that the energy density in the region @xmath286 is always negative , with a divergence at @xmath274 . in our view , only the region @xmath275 should be regarded as physical.,scaledwidth=45.0% ] nonetheless , let us note that the numerical integration of the equations that define the geometry is well defined everywhere except at the point @xmath291 . moreover , the fact that @xmath31 and @xmath194 develop divergences at @xmath274 is not an obstacle to extend the integration across the @xmath274 surface , as a simple change of variables avoids the numerical difficulties associated to the parametrization in terms of @xmath160 . in fact , since @xmath135 is well defined even at @xmath274 , one can write a smooth differential equation for that function . the point is that the divergence in @xmath194 is somehow compensated by the divergence in @xmath31 . considering the ansatz ( [ eq : gttz ] ) to isolate the function @xmath160 , one can compute its derivative and express it in terms of @xmath135 and its first derivative . the resulting equation can be multiplied by @xmath292 on both sides to get rid of all the divergent terms . this new equation can be numerically integrated from the region where it coincides with gr down to @xmath191 . the result is shown in fig . [ fig : metricsp5h ] and is in complete agreement with fig . [ fig : metricsp ] in the overlapping region @xmath293 . the corresponding extension of the geodesics appears in fig . [ fig : affinesp5hor ] . obviously , this region with @xmath286 does not make any physical sense , as it implies a negative energy density that changes from @xmath237 on @xmath294 to @xmath295 on @xmath296 and remains negative until @xmath291 . nonetheless , the numerical problem is well defined all over the @xmath252 domain . down to @xmath191 . both timelike and radial null geodesics take a finite affine time to reach the origin . since the metric in this ( unphysical ) region diverges as @xmath297 , the behavior is analogous to that found in the schwarzschild black hole . , scaledwidth=45.0% ] when @xmath299 and @xmath158 , the model is characterized by @xmath300 as follows from these expressions , the energy density and the functions @xmath31 and @xmath194 are everywhere smooth and finite . one can verify that for @xmath301 the function @xmath258 has a minimum at @xmath275 given by @xmath302 . for this critical value of @xmath98 , the function @xmath194 has a zero at @xmath261 , while for @xmath301 it has two . the former occurs at @xmath261 , while the latter appears at @xmath303 and represents a local maximum ( see fig . [ fig : xdezmm ] ) . for different values of @xmath98 in the model with @xmath304 . , scaledwidth=45.0% ] unlike in the case of sec.[sec : pp ] , the minimum in @xmath258 can not be regarded as representing a wormhole in the auxiliary metric because it is not an absolute minimum in the sense that @xmath175 does not bounce back to infinity after crossing @xmath261 . in the current case , below @xmath261 ( see fig . [ fig : xdezmm ] ) @xmath258 grows just until it reaches a new local extremum , now a maximum , after which it goes monotonically towards @xmath305 as @xmath291 . the interpretation of this structure in the auxiliary geometry is unclear and will not be explored further in this paper . since the existence of an internal wormhole or other structures in the auxiliary geometry does not impose any restriction on the radial function @xmath128 that defines the area of the two - spheres in the physical spacetime , we will assume that @xmath128 is naturally defined over the whole region @xmath306 . an expansion of the metric in the @xmath291 region leads to @xmath307 \ , \end{aligned}\ ] ] which shows that @xmath135 diverges at the center if @xmath308 . when @xmath200 , the above expansion is not valid and must be re - evaluated , leading to @xmath309 which is completely regular at @xmath191 . in this particular case , one verifies that the geometry at @xmath191 becomes of de sitter type , with @xmath310 and finite curvature scalars . it is also worth noting that by a simple rescaling of the time coordinate , @xmath311 , the metric @xmath5 becomes minkowskian at the center , showing that these coordinates locally represent free falling observers . by inspecting the geodesic equation ( [ eq : geozgtt ] ) shows that if @xmath312 then non - radial and timelike geodesics bounce before reaching to the center ( like in the usual reissner - nordstrm black hole of gr ) . however , if @xmath313 ( schwarzschild like configuration ) nothing prevents those geodesics from getting there in a finite affine time . radial null geodesics also reach the center regardless of the value of @xmath122 . it should be noted that curvature divergences exist at @xmath191 as long as @xmath308 . but note that these divergences arise despite the fact that the energy density is finite everywhere , as in case i of sec . [ sec : pm ] . on the other hand , when @xmath200 , we have seen above that the geometry near the center is of de sitter type and , therefore , the geodesics reaching there should not experience any pathological effect , being able to cross the center and continue their path . configurations with @xmath314 should thus be regarded as nonsingular . in this sense , the fact that radial null geodesics are insensitive to the value of @xmath122 suggests that they should always be able to go through the _ apparently pathological _ region @xmath191 even when @xmath308 . this view is further reinforced by the lack of correlation between the behavior of curvature scalars , divergent for @xmath308 , and the energy density , which is always finite . in view of all this , it is unclear whether one should regard any of these solutions as singular , as is typically assumed in the case of gr . therefore , further analysis on the impact of curvature divergences on the transit of physical observers and on the scattering of waves in these spacetimes to get deeper into their singular / nonsingular character seems necessary and will be carried out elsewhere . we now consider the last case , @xmath299 and @xmath315 , which is characterized by @xmath316 in this model the energy density diverges at @xmath274 but , fortunately , this surface lies beyond the physically accessible region . therefore , it can be considered finite beyond @xmath317 . indeed , a glance at the function @xmath31 above puts forward that @xmath166 has a minimum of magnitude @xmath318 at @xmath177 , confirming in this way that this model describes wormholes ( see fig . [ fig : whmp ] ) and that @xmath275 always . for @xmath164 ( solid green curve ) and @xmath319 ( dashed blue curve ) as compared to the gr behaviour @xmath320 ( dashed red line ) in the model with @xmath299 and @xmath315 . this shows that the physical metric describes a wormhole structure . far from the central region the gr behavior is recovered @xmath321.,scaledwidth=45.0% ] a series expansion of the metric about @xmath171 leads to @xmath322 which is always negative and divergent at the throat , implying the existence of curvature divergences on that surface . with this behavior near the throat , a glance to the geodesic equation ( [ eq : geozgtt ] ) indicates that all timelike and non - radial geodesics ( @xmath234 ) bounce before reaching the wormhole , just like in the reissner - nordstrm black holes of gr . for radial null geodesics , however , one finds @xmath323 which implies that @xmath324 diverges as @xmath238 , confirming that such geodesics take an infinite affine time to reach ( or come out from ) the wormhole throat , similarly as in the case @xmath288 of sec.([sec : pm ] ) . this model , therefore , always yields geodesically complete , nonsingular spacetimes . note also that , though the geometry has curvature divergences at @xmath171 , the energy density is finite there , taking the value @xmath325 . in this work we have considered the problem of classical , non - rotating black holes in a quadratic palatini @xmath0 extension of gr . as matter fields we have taken an anisotropic fluid whose stress - energy tensor , besides satisfying the energy conditions , covers a number of interesting cases , in particular , that of non - linear models of electrodynamics . the latter have been frequently employed in the context of gr in order to take care of the singularity problem , but the strategy applied has been unsatisfactory so far . in contrast , the non - trivial interaction between gravity and matter in our case , which is encoded in the ( gravity and matter ) parameters @xmath97 and @xmath71 , yields a number of novelties on the corresponding spacetimes . these geometries quickly recover the reissner - nordstrm solution of gr far from the center , but drastically modify the innermost structure . the corresponding analysis is split into four different cases , according to the signs of @xmath97 and @xmath71 . [ cols="^,^,^,^,^,^",options="header " , ] * in the case @xmath288 two classes of configurations are found , according to a certain critical scale , parameterized by @xmath164 . if @xmath326 , the nature of the central point - like singularity ( timelike , spacelike or null ) , is qualitatively similar to that found in certain families of models of non - linear electrodynamics , and the same applies to the structure of horizons @xcite . in such a case one finds both divergence of curvature scalars and incompleteness of geodesics , hence these spacetimes are regarded as singular . but when @xmath327 the point - like singularity is shifted to a spherical surface of radius @xmath328 , which corresponds to the minimum of the radial function @xmath166 and represents the throat of a wormhole . despite curvature scalars being divergent on this surface , we have explicitly shown that this does not prevent the completeness of geodesics for null and timelike observers , in such a way that the wormhole always lies on the future ( or past ) boundary or the manifold and can not be reached in finite affine time by geodesic observers . the limiting case @xmath164 has a number of peculiar features , such as complete radial null geodesics but incomplete non - radial and timelike geodesics for certain configurations ( with @xmath253 ) . this allows us to conclude that the cases with @xmath329 represent singular spacetimes , while those with @xmath178 are nonsingular and possess a wormhole structure . nonetheless , note that in all these cases ( both nonsingular and singular ) the energy density of the fluid is everywhere finite . * for the case @xmath276 one finds that it is the auxiliary metric which has a wormhole at @xmath274 , while the physical metric becomes finite there , exhibiting up to four horizons . the @xmath274 surface is a region of divergent energy density of the fluid , which is reached in finite affine time by null and timelike geodesics , but nonetheless the curvature scalars are finite there . the metric itself admits an analytical extension to the region @xmath286 , but the spacetime would still be geodesically incomplete and , besides , the breakdown of the fluid model at @xmath274 seems to indicate the unphysical character of such an extension . * in the case @xmath330 no wormhole solution is found and the metric is naturally extended down to @xmath191 . an expansion of the physical metric there reveals that curvature divergences are present as long as @xmath331 , but do disappear for the choice @xmath332 , for which the metric at the center has a de sitter behavior . nonetheless , in both cases the energy density is everywhere finite . in the finite curvature cases , @xmath332 , radial null geodesics reaching the @xmath191 region can clearly continue their path . given that these geodesics are insensitive to the value of @xmath122 , one is tempted to interpret all such radial geodesics as complete , including the cases with @xmath308 . this interpretation is appealing but risky , as it would logically lead to the conclusion that the reissner - nordstrm black hole of gr is nonsingular ( as far as geodesic motion is concerned ) . to deepen into this question , an analysis on the impact of curvature divergences on congruences of observers and on the propagation of waves would be necessary along the lines of refs.@xcite and @xcite . * for the case @xmath333 , it always yields wormhole structures that naturally provide geodesically complete spacetimes , much in the same way as in the @xmath288 case for @xmath178 . note that this is so despite the fact that curvature divergences are always present at @xmath171 , but the energy density is finite there . in table [ table : i ] we display the most relevant features of the four classes of configurations classified according to the combinations of signs of @xmath97 and @xmath71 . such features are i ) the existence or not of wormhole configurations and the behaviour at the wormhole throat ( or at the center when no such wormhole exists ) of the following objects : ii ) the metric components , iii ) the energy density , iv ) the curvature scalars , and v ) the completeness ( or not ) of all null and timelike geodesics on such spacetimes . from this table it is clear the breakdown of the correlations between the behaviour of energy density , curvature scalars and completeness of geodesics in different ways . the research presented in this work is added to the growing set of results within metric - affine geometries supported by @xmath0 gravity @xcite , quadratic @xmath334 and eddington - inspired born - infeld gravities @xcite , where the point - like singularity of gr is replaced by a wormhole structure , which allows geodesics to be complete . the results obtained so far seem to point out two different mechanisms for the resolution of spacetime singularities in this context . ( i ) : for @xmath0 theories the wormhole lies on the future ( or past ) boundary of the spacetime , but the fact that geodesics can be indefinitely extended means that these spacetimes are nonsingular according to the criteria employed in the singularity theorems @xcite . ii ) : for the cases of quadratic and born - infeld gravity ( which admit extensions to higher @xcite and lower @xcite dimensions with similar results ) , the wormhole may be reached in a finite affine time by some geodesics , but they are naturally extended through it . it should be stressed that in the latter case one may wonder about the physical impact of curvature divergences on physical ( extended ) bodies crossing the wormhole throat , since the presence of large tidal forces could rip them apart . in this sense , in four - dimensional born - infeld gravity a separate analysis using a congruence of geodesics to model such extended bodies has revealed that curvature divergences occurring at the wormhole throat do not pose any destructive threat , being the transit smooth and weakly affected by the large tidal forces at the throat @xcite . the problem of scalar wave scattering off this wormhole turns also to be well posed @xcite . to conclude , the results obtained in this paper provide a fauna of examples on which the ( typically assumed ) correlations among curvature divergences , energy density , and geodesic ( in)completeness are explicitly broken . the emergence of structures such as wormholes appears as a key element for the extendibility of geodesics ( note that we also found a de sitter interior which guarantees the extendibility of geodesics in a particular example ) . these non - perturbative features should be taken into account in the interpretation of the existence of divergences in curvature scalars or in the matter fields . those infinities are significant in perturbative frameworks , where they signal the end of validity of a certain approximation , but in a non - perturbative scenario their interpretation is unclear . it is worth noting , in this sense , that in systems such as graphene , wormholes have been constructed in the discrete description through a careful design of the lattice , adding a series of heptagonal rings that help join two flat sheets with a carbon nanotube @xcite . in the continuized description , the wormhole exhibits a curvature divergence at the throat which does not prevent the study of fermion propagation in the resulting effective geometry . this example is , in our view , very representative of what may correspond to a quantum version of the models presented here : geodesic completeness is guaranteed by non - perturbative aspects ( the wormhole ) , though infinities ( in curvature and energy density ) may arise because of the lack of control of the underlying microstructure in a certain limit @xcite . the behavior of classical and quantum fields in these backgrounds is currently underway . c. b. is funded by the national scientific and technical research council ( conicet ) . g. j. o. is supported by a ramon y cajal contract , the i - coopb20105 grant of the spanish research council ( csic ) , the consolider program cpanphy-1205388 , and the severo ochoa grant sev-2014 - 0398 ( spain ) . d. r .- g . is funded by the fundao para a cincia e a tecnologia ( fct , portugal ) postdoctoral fellowship no . sfrh / bpd/102958/2014 and the fct research grant uid / fis/04434/2013 . this work is also supported by the spanish grant fis2014 - 57387-c3 - 1-p from mineco and the cnpq ( brazilian agency ) project no . 301137/2014 - 5 . c. b. and d. r .- g . thank the department of physics of the university of valencia for their hospitality during the elaboration of this work . this article is based upon work from cost action ca15117 , supported by cost ( european cooperation in science and technology ) . r. penrose , phys . * 14 * , 57 ( 1965 ) ; 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exploring the characterization of singular black hole spacetimes , we study the relation between energy density , curvature invariants , and geodesic completeness using a quadratic @xmath0 gravity theory coupled to an anisotropic fluid . working in a metric - affine approach , our models and solutions represent minimal extensions of general relativity ( gr ) in the sense that they rapidly recover the usual reissner - nordstrm solution from near the inner horizon outwards . the anisotropic fluid helps modify only the innermost geometry . depending on the values and signs of two parameters on the gravitational and matter sectors , a breakdown of the correlations between the finiteness / divergence of the energy density , the behavior of curvature invariants , and the ( in)completeness of geodesics is obtained . we find a variety of configurations with and without wormholes , a case with a de sitter interior , solutions that mimic non - linear models of electrodynamics coupled to gr , and configurations with up to four horizons . our results raise questions regarding what infinities , if any , a quantum version of these theories should regularize .

SECTION 1. SHORT TITLE. This Act may be cited as the ``Military Retirees Health Care Protection Act''. SEC. 2. FINDINGS AND SENSE OF CONGRESS. (a) Findings.--Congress finds the following: (1) Career uniformed service members and their families endure unique and extraordinary demands and sacrifices during the course of a decades-long career protecting freedoms for all Americans. (2) The extent of these demands and sacrifices is never so evident as in wartime, not only in today's Global War on Terrorism, but also during the last 6 decades of hot and cold wars when today's retired service members were on continuous call to enter into harm's way when and as needed. (3) The demands and sacrifices are such that few Americans are willing to accept them for a multi-decade career. (4) The primary offset for enduring the extraordinary sacrifices inherent in a military career is a system of extraordinary retirement benefits, including health care coverage considerably better than that afforded civilian workers, that a grateful Nation provides for those who choose to subordinate much of their personal life to the national interest for so many years. (5) Many private sector firms are curtailing health benefits and shifting significantly higher costs to their employees. (6) One effect of such curtailment is that retired service members who work for such employers increasingly depend on the TRICARE coverage they earned by their military service. (7) While the Department of Defense has made some efforts to constrain TRICARE program costs, a large part of the Department's effort has been aimed at shifting a larger share of cost burdens to retired service members. (8) The beneficiary cost increases proposed by the Department of Defense fail to recognize adequately that career service members paid enormous in-kind premiums through their extended service and sacrifice. (9) A significant share of the Nation's health care providers refuse to accept new TRICARE patients because TRICARE pays them significantly less than commercial insurance programs and imposes unique administrative requirements. (10) The Department of Defense has chosen to count the accrual deposit to the Department of Defense Medicare-Eligible Retiree Health Care Fund against the budget of the Department of Defense, contrary to the amendments made by section 725 of Public Law 108-375. (11) Leaders of the Department of Defense have reported to Congress that counting such deposits against the budget of the Department of Defense is impinging on other readiness needs, including weapons programs, an inappropriate situation which section 725 of Public Law 108-375 was intended expressly to prevent. (b) Sense of Congress.--It is the sense of Congress that-- (1) the Department of Defense and the Nation have a committed health benefits obligation to retired uniformed service members that exceeds the obligation of corporate employers to civilian employees; and (2) the Department of Defense has many additional options to constrain the growth of health care spending in ways that do not disadvantage beneficiaries and should pursue any and all such options rather than seeking large fee increases for beneficiaries. SEC. 3. PROHIBITION ON INCREASES OF CERTAIN HEALTH COSTS AND RESTRICTIONS ON HEALTH BENEFIT ADJUSTMENTS FOR MEMBERS AND RETIREES OF THE UNIFORMED SERVICES AND THEIR DEPENDENTS. (a) Prohibition on Increase in Charges Under Contracts for Medical Care.--Section 1097(e) of title 10, United States Code, is amended in the last sentence-- (1) by striking ``during the period beginning on'' and inserting ``after''; and (2) by striking ``, and ending on September 30, 2011''. (b) Prohibition on Increase in Amount of Cost Sharing Requirement Under Pharmacy Benefits Program.--Section 1074g(a)(6)(A) of title 10, United States Code, is amended by adding at the end the following: ``After September 30, 2011, the dollar amount of a cost sharing requirement (whether established as a percentage or a fixed dollar amount) may not be increased.''. (c) Prohibition on Increase in Charges for Inpatient Care.--Section 1086(b)(3) of title 10, United States Code, is amended by striking ``during the period beginning on April 1, 2006, and ending on September 30, 2011''. (d) Prohibition on Increase in Premiums Under TRICARE Coverage for Certain Members in the Selected Reserve.--Section 1076d(d)(3) of title 10, United States Code, is amended to read as follows: ``(3) Beginning on October 1, 2011, the monthly amount of the premium for TRICARE Standard coverage under this section may not be increased to be more than the amount in effect for the month of September 2011.''. (e) Prohibition on Increase in Premiums Under TRICARE Coverage for Certain Members of the Retired Reserve.--Section 1076e(d) of title 10, United States Code, is amended by adding at the end the following new paragraph: ``(6) Beginning on October 1, 2011, the monthly amount of the premium for TRICARE Standard coverage under this section may not be increased to be more than the amount in effect for the month of September 2011.''.

Military Retirees Health Care Protection Act - Expresses the sense of Congress that: (1) the Department of Defense (DOD) and the nation have a committed health benefits obligation to retired military personnel that exceeds the obligation of corporate employers to civilian employees; and (2) DOD has many additional options to constrain the growth of health care spending in ways that do not disadvantage beneficiaries, and should pursue such options rather than seeking large fee increases for beneficiaries. Prohibits an increase after: (1) April 1, 2006, in a premium, deductible, copayment, or other charge prescribed by the Secretary of Defense for medical and dental health care coverage for military personnel; and (2) September 30, 2011, in the dollar amount of a cost-sharing requirement under the DOD pharmacy benefits program. Prohibits: (1) charges for DOD inpatient care from exceeding $535 per day; and (2) beginning on October 1, 2011, an increase in premiums under TRICARE (a DOD managed health care program) for certain members of the Selected Reserve and Retired Reserve.

we conducted a population - based retrospective cohort study using administrative databases from ontario , canada , that included hospital discharge abstracts , physician service claims , and demographic data . the ontario diabetes database is a validated registry of physician - diagnosed nongestational diabetes that is identified using these administrative data ( 7 ) . individuals are linked between all data sources via a unique health card number , which is reproducibly encrypted in all of these data sources . women aged 2049 years who had a hospitalization record indicating a live birth between april 1994 and march 1997 were selected . for women who had more than one birth during this period , those who had pregestational diabetes or a cvd event ( as defined below ) in the prior 3 years were excluded . baseline characteristics were age at delivery , region of residence , and socioeconomic status ( measured as the neighborhood income quintile ) . women were defined as having gdm using an algorithm analogous to that used by the validated registry to exclude gdm : one hospitalization record or two ambulatory physician claims bearing the diagnosis of diabetes or gdm between 120 days before and 180 days after delivery . the primary outcome ( cvd events ) was defined as a hospitalization for acute myocardial infarction , stroke , coronary artery bypass , coronary angioplasty , or carotid endarterectomy . the prespecified secondary outcome ( coronary artery disease [ cad ] events ) was hospitalization for acute myocardial infarction , coronary artery bypass , or coronary angioplasty . although the registry does not distinguish between types , the majority of women developing diabetes in this group would have type 2 diabetes . cox proportional hazards regression was used to model the association of gdm with each outcome , accounting for the matched design of the study . for each outcome , an unadjusted model and a model adjusting for subsequent diagnosis of diabetes as a time - dependent covariate were built . the assumption of proportionality was verified by plotting log(log[survival ] ) versus log(time ) to assess parallelism . however , 3,127 were excluded because of preexisting diabetes , and 43 were excluded because of previous cvd . a further 2,036 were excluded due to missing data , mostly socioeconomic status . of the remaining 351,685 subjects , 8,194 ( 2.3% ) had gdm during the index pregnancy . diabetes developed during follow - up in 2,214 ( 27.0% ) of the women with gdm and 2,596 ( 3.2% ) of the women without gdm . significant associations were found between gdm and both outcomes , but these associations were attenuated following adjustment for subsequent diabetes . our study is the first of its kind to show that young women with gdm have a substantially increased risk for cvd relative to women without gdm . the subsequent development of type 2 diabetes accounts for much of this increased risk , which reinforces the vital need for diabetes prevention strategies in this high - risk population . our findings are consistent with a cross - sectional study conducted by carr et al . ( 5 ) , which reported that women with a history of gdm had odds ratios for cvd and cad similar to those reported here ( 1.85 and 1.58 , respectively ) . however , this study was cross - sectional and relied on retrospective self - report to ascertain exposures and outcomes . in contrast , our cohort study used a more rigorous end point assessment and followed a much larger population of women over many years . our study used administrative data where clinical information , such as cardiovascular risk factors , was unavailable . women with gdm exhibit chronic insulin resistance ( 8) , which is associated with a clustering of risk factors that are in the causal pathway to cvd . therefore , women with gdm likely have very different risk factor profiles than those without gdm , and adjusting for these differences might obscure a clinically important association between gdm and cvd . in summary , women with gdm are at increased risk for cvd events compared with women without gdm , and much of this risk is attributable to the subsequent development of type 2 diabetes . as diabetes prevention interventions in women with a history of gdm have also been shown to slow progression of atherosclerosis ( 9 ) , this study highlights the importance of diabetes prevention for this high - risk population .

objective to determine whether women with gestational diabetes mellitus ( gdm ) have an increased risk of cardiovascular disease ( cvd ) following pregnancy.research design and methods all women aged 2049 years with live births between april 1994 and march 1997 in ontario , canada , were identified . women with gdm were matched with 10 women without gdm and were followed for cvd.resultsthe matched cohorts included 8,191 women with gdm and 81,262 women without gdm . mean age at entry was 31 years , and median follow - up was 11.5 years . the hazard ratio for cvd events was 1.71 ( 95% ci 1.082.69 ) . after adjustment for subsequent type 2 diabetes , the hazard ratio was attenuated ( 1.13 [ 95% ci 0.671.89]).conclusions young women with gdm had a substantially increased risk for cvd compared with women without gdm . much of this increased risk was attributable to subsequent development of type 2 diabetes .

zika virus ( zikv ) is an arthropod - borne virus ( arbovirus ) transmitted by aedes spp . in recent years , outbreaks of zikv infection have occurred , and the infection has been linked to severe neurological complications , including microcephaly and guillain barr syndrome ( gbs ) . in this article , we first briefly review the biology and epidemiology of zikv and then critically address the literature available regarding the neurobiology of zikv and its potential neuropsychiatric manifestations . zikv is a positive single - strand enveloped rna virus that belongs to the family flaviviridae and genus flavivirus . zikv genome includes two noncoding regions and one region encoding a polyprotein that is cleaved into capsid , membrane precursor , and envelope , and also seven nonstructural proteins.1,2 based on the phylogenetic tree reported by weaver et al,3 zikv differs from other flavivirus by 20% nucleotide sequence divergence . the prototype zikv mr 766 was first identified in africa.47 in asia , lanciotti et al8 described a coding region of zikv 2007 ec and the nonstructural protein 5 ( ns5 ) gene , corresponding to a flavivirus sequence , showing a high homology of the asian strain with the virus originally identified in africa . accordingly , it has been proposed that the asian cluster was phylogenetically derived from the african zikv strain.2,8,9 the first cases of zikv infection reported in brazil were from a strain genetically related to the asian lineage.1012 the introduction of zikv in brazil probably occurred in 2014 due to the arrival of foreign tourists and athletes during the soccer world cup and/or other sport events.11,12 giovanetti et al13 described the complete genome of zikv isolated in brazil , confirming that this cluster is similar to the virus isolated in french polynesia.13,14 the denomination zika came from a forested area in uganda , where zikv was first identified in rhesus monkeys during a research about yellow fever cycle and other arboviruses.5 the virus was also identified in mosquitoes.4,6,7 later , boorman and poeterfield15 proved the transmission from laboratory - infected aedes aegypti mosquitoes to rhesus monkeys . dick6 inoculated zikv in mice and detected virus replication in the brain . some mice exhibited motor weakness and paralysis , and susceptibility to infection appeared to decrease with age . the first evidence of human infection based on the identification of antibodies against zikv came from patients in uganda and nearby areas.6 later , macnamara17 reported the isolation of zikv in one patient and the rise of antibody serum titles in two patients during an investigation of jaundice in nigeria . sporadic cases of zikv infection had been reported in africa and asia until 2007 , when an outbreak occurred in yap state , federated states of micronesia.8,18 lanciotti et al8 identified several cases of zikv infection by using serological and molecular analysis during this outbreak . duffy et al18 investigated suspected cases of zikv presenting macular or papular rash , arthritis or arthralgia , and non - purulent conjunctivitis . from 185 suspected cases , 49 ( 26% ) cases were confirmed by positive reverse transcriptase polymerase chain reaction ( rt - pcr ) for zikv . in addition , 414 ( 74% ) of 557 investigated subjects had igm anti - zikv in blood samples , but only 156 of those reported clinical symptomatic illness.18 more recently , in october 2013 , a mild dengue - like illness was described in french polynesia.19,20 approximately 19,000 suspected cases were estimated , but zikv infection was confirmed in only 294 ( 49.5% ) of 584 patients submitted to serological tests.19 subsequently , the virus spread to other countries , and several cases were described throughout the world , including japan , australia , europe , and latin america.12,21 the first autochthonous cases in brazil were published in june 2015 that referred to patients who acquired the infection by march 2015.10 these patients exhibited fever , rash , conjunctivitis , and arthralgia with negative molecular and serological examinations for dengue and chikungunya viruses . zikv infection was confirmed by rt - pcr.10 a case of zikv infection acquired in march 2015 by an italian traveler returning from brazil was also reported in june 2015.22 in the first semester of 2015 , health services in two states of the northeast of brazil ( pernambuco and bahia ) reported a significant rise in the frequency of patients with mild fever , maculopapular rashes , headaches , non - purulent conjunctivitis , arthralgia , and myalgia . serological tests for dengue and chikungunya viruses were negative , and zikv was detected by rt - pcr.11,23 another outbreak was described in the southeast region , in rio de janeiro , with the identification of 364 suspected cases.24 among 262 cases tested for zikv infection , 119 ( 71.9% ) had zikv rna in serum collected during the acute phase of the disease.24 subsequently , the brazilian ministry of health reported that autochthonous transmission of zikv occurred in 18 states of the country from april to november 2015.25 in april 2016 , a total of 91,387 cases of zikv infection had been reported in all brazilian states , with an incidence of 44.7/100,000 inhabitants.26 simultaneous infections of zikv and dengue virus were also described.27 from brazil , zikv spread to other latin american countries due to the large availability of the vector a. aegypti . even in temperate regions with limited presence of the vector , there is great concern with possible autochthonous cases , especially through sexual transmission.28,29 the first evidence of perinatal transmission of zikv was confirmed in two cases during the largest outbreak in french polynesia.30 both mothers presented cutaneous rash after delivery . both mothers and newborns were serum positive by rt - pcr , and vertical transmission possibly occurred by transplacental route or during delivery.30 in october 2015 , the brazilian ministry of health issued an official communicate stating that 26 cases of neonatal microcephaly were notified from public and private services in pernambuco state.31 microcephaly is a neurological syndrome that can be associated with other malformations and is closely related to the development of the central nervous system ( cns).32 its definition and clinical relevance vary among authors.3335 for instance , cutoff points of head circumference measures 2 or 3 standard deviation ( sd ) ( from the mean expected values for age and sex ) have been adopted . children with head circumference 3 sd are considered as having severe microcephaly , and they are more likely to have other structural abnormalities , more severe developmental impairment , and cognitive and behavioral problems than those with milder microcephaly.34,35 until november 17 , 2015 , 399 suspected cases of microcephaly were identified in seven states of the northeast of brazil . onward , the brazilian ministry of health recommended that all cases of microcephaly should be immediately reported.36 this event was reported to the world health organization ( who ) and classified as a potential public health emergency.37 it is worth mentioning that , until december 2015 , the official parameter adopted for microcephaly definition in brazil considered the cephalic perimeter <33 cm for term newborns.38 from that point until march 2016 , the parameter adopted for microcephaly notification was changed to a cephalic perimeter < 32 cm for term newborns of both sexes.38 this criterion change was proposed to increase the specificity of the test.39 in parallel to those official reports , confirmed cases of zikv infection in fetus and newborns have been published.4042 the first reports identified virus genome in the amniotic fluid of two pregnant women whose fetuses had microcephaly,41,42 and in samples collected from a deceased neonate with 19 cm head circumference and severe hydrops who died just after birth.40 calvet et al41 and oliveira melo et al42 described two cases in which amniotic fluid was collected from two pregnant brazilian women who developed symptoms compatible with zikv infection at 10 and 18 weeks of gestation and whose fetuses had microcephaly . ultrasound ( us)-guided transabdominal amniocentesis was performed at 28 weeks of gestation , and zikv genome was identified in the amniotic fluid of both pregnant women , but not in their urine or serum . fetal us at 2527 weeks of gestation revealed severe cns abnormalities , including microcephaly , asymmetric hemispheres , ventriculomegaly , hypoplastic cerebellum , and hypoplasia / absence of the cerebellar vermis . one infant was born at 40 weeks of gestation with a head circumference of 30 cm , while the other newborn presented severe ventriculomegaly , microphthalmia , cataract , and severe arthrogryposis in legs and arms.41,42 due to the temporal coincidence of these events , a possible association of microcephaly and zikv infection was hypothesized by the brazilian ministry of health.40,43 since then , a special task force was established to investigate the association between microcephaly and zikv infection during pregnancy . notification of all cases of microcephaly became mandatory and in any case of pregnant women with suspected zikv infection pregnancy outcome must be monitored . on december 1 , 2015 , given the increase in congenital abnormalities , gbs , and other neurological manifestations possibly related to zikv , the who released an epidemiologic alert with recommendations , including surveillance , case definition , diagnosis , vector control , and prevention measures for public health proceedings.37 on january 22 , 2016 , a report including the participation of the brazilian medical genetics society zika embryopathy task force was posted in the centers for disease control and prevention ( cdc ) morbidity and mortality weekly report.44 in this report , schuler - faccini et al44 described 35 infants with microcephaly that had been born from august to october 2015 in eight among 26 states of brazil . four ( 11% ) infants had low birth weight , while arthrogryposis , talipes , microphthalmia abnormalities in fundoscopic examination were also reported . all mothers had lived in and/or visited zikv - affected areas during pregnancy , and 74% presented a skin rash during the first ( n=21 ) or second ( n=5 ) trimesters of pregnancy computed tomography ( ct ) scans and transfontanellar cranial uss identified brain calcifications ( periventricular , parenchymal , thalamic , and in the basal ganglia areas ) , lissencephaly , pachygyria , and ventricular enlargement.44 other studies reported zikv infection during pregnancy with confirmation of the virus by rt - pcr in both mother and fetus samples . on february 10 , 2016 , in slovenia , mlakar et al45 described a 25-year - old woman who previously lived in the northeast of brazil and exhibited , during the 13th week of gestation , a generalized maculopapular rash , high fever , severe musculoskeletal , and retro - ocular pain and itching , parallel to zikv epidemic in that community . the ultrasonography , at 29 weeks of gestation , identified intrauterine growth retardation ( fetal weight at third percentile ) , microcephaly , moderate ventriculomegaly , and numerous calcifications in the placenta . pregnancy was terminated at 32 weeks and fetal autopsy confirmed microcephaly , almost complete agyria , hydrocephalus , and multifocal dystrophic calcifications in the cortex and in the subcortical white matter.45 simultaneously , another two cases of fetal loses and two cases of early neonatal deaths were described by martines et al.46 all four mothers presented rash during the first trimester of pregnancy , but they were not tested for zikv . the two newborns died within 20 hours of life , and the histopathologic evaluation of brain showed parenchymal calcification , microglial nodules , gliosis , cell degeneration , and necrosis . investigation for all other infectious agents related to vertical transmission was negative.46 on february 25 , 2016 , sarno et al47 reported a case of fetal death at 32 weeks of pregnancy , without a clear previous history of zikv infection . obstetric ultrasonography showed microcephaly , hydranencephaly , intracranial calcifications , and destructive lesions of posterior fossa . pregnancy interruption occurred at the 32nd week , and rt - pcr was positive for zikv in cerebral , cortex , and medulla , and in amniotic fluid.47 in march 2016 , driggers et al48 published a case of a 33-year - old north american woman who had been in mexico , guatemala , and belize with her husband on holidays . this woman developed fever , myalgia , ocular pain , and a skin rash in her eleventh week of gestation . serologic analyses were positive for igg antibodies and negative for igm antibodies against dengue virus , and positive for both igg and igm antibodies against zikv , and the virus was also detected by rt - pcr assay at 16 and 21 weeks of gestation . diffuse atrophy of the cerebral mantle , especially in the frontal and parietal lobes , and of corpus callosum was identified at the 20th week by magnetic resonance imaging ( mri ) , and fetal head circumference decreased in sequential us images from the 47th to 24th percentile between 16 and 20 weeks of gestation . on postmortem analysis , the highest viral loads were found in fetal brain , but zikv was also identified in placenta , umbilical cord , and other fetal tissues , including muscle , liver , lung , and spleen.48 in march 2016 , the cdc also published a retrospective analysis of cases from the period of august 2015 to february 2016.49 a total of 257 women were evaluated and 97% tested negative for recent zikv infection . among the nine cases with confirmed zikv infection ( rt - pcr , immunohistochemistry , and/or serologic tests in amniotic fluid , placenta , or serum ) , six pregnant women reported symptoms during the first trimester : two early pregnancy losses occurred , two pregnancies were electively terminated , one infant with microcephaly was born alive , and one pregnancy was still continuing when the article was published . in three women whose symptoms occurred during the second and third trimesters , no abnormalities were identified in the newborns.49 a cohort study from rio de janeiro / brazil enrolled 88 pregnant women ( from 5 to 38 weeks of gestation ) who had started with cutaneous rash within the 5 days prior the study recruitment.46 zikv infection was identified by real - time rt - pcr in 72 ( 82% ) of them in blood and/or urine samples . us was performed in 42 women with positive zikv infection , and fetal abnormalities ( in utero growth restriction with or without microcephaly , ventricular calcifications , abnormal amniotic fluid volume , or altered cerebral or umbilical artery flow ) were detected in 29% of them . two fetal deaths occurred at 36 and 38 weeks of gestation.50 in april 2016 , three studies described image changes in brazilian cases of microcephaly.5153 a study from recife , the capital of the state of pernambuco / brazil , evaluated 23 infants with congenital microcephaly and epidemiology suggestive of congenital zikv infection.51 zikv igm antibodies were detected in the cerebrospinal fluid of seven infants . brain ct showed intracranial calcifications in all cases , mainly in frontal and parietal lobes and at the corticomedullary junction , basal ganglia , and thalamus . ventriculomegaly ( severe in 53% ) and global hypogyration of the cerebral cortex were also found in all infants . cerebellar hypoplasia and abnormal hypodensity of the white matter were also described.51 in another study from pernambuco , neuroradiological examinations of children with a diagnosis of microcephaly , who were born during the zikv outbreak in 2015/2016 , were retrospectively evaluated.52 after the exclusion of other known causes of microcephaly , the final sample with suspect zikv infection comprised 23 infants . in six cases , cerebrospinal fluid was analyzed and igm antibodies against zikv were positive . in the remaining 17 infants , descriptions of the radiological abnormalities identified in cts included decreased brain volume , ventriculomegaly , and cerebral calcifications ( in cortical and subcortical junctions , basal ganglia , and periventricular areas ) . simplified gyral pattern , hypogenesis / hypoplasia of corpus callosum , and delayed myelination were also described in mri examinations.52 cavalheiro et al53 evaluated 13 term newborns with microcephaly , whose mothers presented cutaneous rash within the first 4 months of pregnancy . other infectious agents were excluded . in all of them , decreased cerebral mantle , increased subarachnoid space and ventriculomegaly , lissencephaly , and hypoplasia of the corpus callosum were observed in brain ct and/or mri . only one case exhibited periventricular calcifications , whereas , in others , calcifications were mostly localized in the subcortical / cortical transition area and in the basal ganglia.53 in may 2016 , another case report from rio de janeiro described a 27-year - old woman , within the 12th week of gestation exhibiting symptoms of fever , maculopapular rash , and arthralgia.54 serology testing for congenital infections and dengue and chikungunya virus was negative . normal fetal anatomy was seen in us examinations at 12 and 21 weeks of gestation , but microcephaly was suspected at the 32-week scan . neonatal head circumference was 29.0 cm , and transfontanellar us examination identified subcortical and periventricular calcifications with ventricular dilatation . postnatal ct also revealed brain calcifications , cortical atrophy , small anterior fontanel , and premature closure of coronal and metopic sutures.54 up to may 7 , 2016 , the brazilian ministry of health reported 7,438 suspected cases of microcephaly , among which 2,679 cases were excluded and 3,433 were still under investigation . a total of 1,326 cases of microcephaly were confirmed , but only 205 of them had laboratorial confirmation of zikv infection.55 studies also retrospectively evaluated the frequency of fetal abnormalities possibly due to zikv outbreak in french polynesia that affected ~66% of the population.56,57 in the 23-month period included in the study , eight cases of microcephaly were identified , of which five resulted in termination of pregnancy by medical abortion.56 this study estimated the risk of microcephaly after zikv infection in pregnancy in 0.95% , and the first trimester seems to be the period at highest risk.56 it is worth mentioning that , based on the analysis of brazilian data , johansson et al57 proposed the risk of microcephaly ranging from 0.88% to 13.2% of zikv infection occurring in the first trimester of pregnancy , depending on the overall infection rate estimates . the lower end of this range was similar to the ~1% risk estimated for french polynesia . still there , a retrospective evaluation of 19 cases of congenital cerebral malformations , including five cases of microcephaly , described positive identification of zikv rna by rt - pcr in four of them.58 another study reviewed the occurrence of fetal abnormalities in 4,285 births in the polynesia hospital center.59 twelve cases of malformations were identified , and among them three cases of fetuses with severe cns abnormalities and positive pcr for zikv in the amniotic fluid . microcephaly , low cerebellar biometry , occipital subependymal pseudocysts , polymicrogyria with laminar necrosis and opercular dysplasia , absent / or hypoplastic corpus callosum , and hypoplastic brainstem were detected through mri.59 the studies describing radiological abnormalities of the cns in fetuses and neonates with presumed congenital zikv infection are summarized in table 1 . ocular abnormalities in neonates possibly associated with zikv infection have also been reported . in a sample of 29 infants , from salvador , bahia , brazil , with microcephaly and a presumed diagnosis of congenital zikv infection , ocular abnormalities were found in ten children ( 34.5% ) , and , in seven , the alterations were bilateral . the authors described focal pigment mottling of the retina and chorioretinal atrophy , optic nerve abnormalities , bilateral iris coloboma , and lens subluxation . from this sample , 23 mothers reported symptoms compatible with zikv infection during pregnancy , of which 18 occurred in the first trimester , four in the second trimester , and one in the third trimester.60 a study from recife , pernambuco , brazil , showed ten infants with similar ocular abnormalities , including gross pigment mottling and/or chorioretinal atrophy and optic nerve abnormalities . seven mothers ( 70% ) referred symptoms during pregnancy , six of them in the first trimester.61 unfortunately , the diagnosis of zikv infection was based on the clinical symptoms of the mother during pregnancy , and also the exclusion of other infections such as syphilis , hiv , toxoplasmosis , cytomegalovirus , herpes simplex virus , and rubella . the absence of a unified definition of microcephaly has had important epidemiological consequences . since march 2016 , the official criteria used to diagnose microcephaly in brazil have been based on the who recommendations:61,62 1 ) for term babies , international parameters of the who should be used and 2 ) for preterm newborns , the intergrowth parameters should be used . initially , the definition of cases of microcephaly in the surveillance system included all full - term infants with a head circumference 33 cm , and later the inclusion criteria were modified to 32 cm.63 however , the national live birth information system adopted a definition of microcephaly when head circumference measure was 3 sd from the mean expected for age and sex.64,65 therefore , variations in the number of suspected cases may have occurred according to the definitions adopted and may have resulted in lower diagnostic specificity , leading to possible overestimation of affected infants.39,65 furthermore , the real incidence of microcephaly in brazil , prior to the occurrence of zikv infectious , was possibly underestimated , especially in the northeast region , and the obligatory notification of cases may falsely inflate the real incidence.39,66,67 in a communicate , the latin american collaborative study of congenital malformations ( eclamc 2015 ) questioned the number of reported cases , stating that they were much higher than the expected considering the incidence of zikv infection in the brazilian population.68 other possible etiologies of microcephaly including environmental , alcohol - related , infectious or genetic , and/or associated factors ( malnutrition , coinfection with other agents ) also must be more carefully investigated.66 congenital microcephaly is clearly associated with genetic and acquired conditions ( for review , refer nunes et al69 ) . exposure to drugs , including alcohol , maternal infection , and nutritional deficiency is the major cause of acquired congenital microcephaly . regardless of the cause , the etiopathogenic factor must influence the proliferation phase of the cns development , around third and fourth months of pregnancy , to determine microcephaly . accordingly , zikv infection could cause microcephaly only when occurring in the first months of pregnancy . in this regard , convincing epidemiological data are missing.70 although this relationship still needs further clarification , some of the evidence described so far suggests the possibility of zikv - related teratogenic effects.44,71,72 in terms of public health safety measures , while prospective studies are not finalized and/or more robust evidence is available , precautions to control vector multiplication and to reduce individual exposure to the virus , especially in fertile and pregnant women , are recommended throughout the world.31,37,73 the continuous surveillance of suspected cases is also maintained , and a recent report from the who74 enlists eight countries that have reported cases of microcephaly and/or cns malformations that were potentially associated with zikv infection : brazil , cape verde , colombia , french polynesia , martinique , panama , slovenia , and the usa . in the last two countries , the probable place of infection table 2 depicts arguments for and against a causal association between zikv infection and microcephaly . zikv infection has been linked to severe neurological complications , that is , microcephaly and gbs . while the first condition involves the cns and the second is related to peripheral nerves lesion . alternatively , neuronal lesion could result from zikv - elicited processes , including immune response and loss of glial support . so far , studies have focused on the first hypothesis implicating a direct effect of zikv on neurons . although suggestive , the detection of zikv in the brain of microcephalic human fetus45 does not prove either causality or pathogenic mechanism . to overcome the limitations of human studies , in vitro and in vivo experimental approaches two independent studies showed that zikv can infect neural stem cells in vitro , inducing caspase - mediated cell death.75,76 the most compelling evidence for a direct role played by zikv in microcephaly came from an elegant study using induced pluripotent stem cells cultured as neurospheres and brain organoids , in in vitro models of embryonic brain development . garcez et al76 showed that zikv reduced the viability and growth of neural stem cells in these models , disrupting the formation of both structures . to control for unspecific effects of viral infection on neurogenesis , the same experiments were performed with dengue virus 2 , a flavivirus with genetic and serological similarities to zikv . neurospheres and brain organoids exposed to dengue virus 2 did not have their growth and development altered , suggesting that neurogenesis impairment is not a general feature of the flavivirus family.76 until recently , only a very limited number of studies had been performed in rodents , indicating that zikv can replicate and damage cns cells.77,78 among the concerns regarding these older studies , there is the use of the prototype mr 766 strain of zikv that had undergone multiple passages in suckling mouse brains , possibly changing its biological properties , including virulence . alterations in molecular components of zikv overtime could also be responsible for its increased neuropathogenicity lately . to overcome these limitations , lazear et al79 assessed four zikv strains ( three strains isolated from mosquitoes in africa and one contemporary clinical isolate ) in wild - type ( wt ) c57bl/6 mice and immune - deficient transgenic mice . four- to six - week - old wt mice inoculated with zikv by subcutaneous route did not develop any clinical sign of disease , while different strains of mice lacking interferon / ( or type 1 ) signaling developed neurological signs ( muscle weakness ) and succumbed to the infection . ifnar1/ mice , which can not respond to interferon / , were highly vulnerable to the infection and exhibited high levels of zikv in all tissues evaluated , including blood , spleen , testes , brain , and spinal cord . interestingly , zikv could cause disease in non - weaned wt mice , that is , 1-week - old , when the innate immune response is not yet mature , indicating an age - dependent vulnerability to disease.79 besides proposing a model for therapeutic and pathogenesis investigation , this study confirmed a pivotal role played by interferon / in restricting zikv infection , as already described for dengue virus infection . rossi et al80 also suggested a significant role played by type i interferon in the resistance against zikv infection . using a cambodian isolate inoculated by intraperitoneal route , they found that 3-week - old 129sv mice lacking the interferon / receptor ( a129 ) succumbed to the infection , while immunocompetent mice survived . an age - dependent vulnerability to disease was also demonstrated in this model with 3-week - old mice exhibiting more severe signs of infection than 5- and 11-week - old mice . zikv was detected in the brain on day 3 postinfection and caused neurological signs ( lethargy , tremor ) by day 5 postinfection , especially in 3-week - old a129.80 mice lacking both interferon / and ( or type ii ) receptors ( ag129 ) infected by intraperitoneal or intradermal routes also developed a severe disease , dying on day 6 postinfection . given the antiviral activity of interferons , these results were not surprising , being also corroborated by an in vitro study showing the potential of interferons / and in controlling zikv replication.81 the major limitation of the models proposed so far pertains to the fact that susceptible animals lack a key component of the innate immune response against viral infection . this certainly influences how the immune system deals with the zikv infection , affecting the evaluation of the real role played by immune mechanisms on disease pathogenesis . in fact , mechanistic insights are still missing in in vivo studies , particularly those related to neuronal damage . in addition , it is uncertain whether zikv promotes widespread or localized brain damage , and careful neuropathological analysis coupled with behavioral assessment is warranted in these and future animal models of zikv . the age - dependent vulnerability to disease this latter issue is of paramount importance taking into consideration the controversies regarding the association between prenatal zikv infection and microcephaly . more importantly , it is uncertain the consequences of zikv infection after this critical period on cns development . theoretically , neuronal migration , organization , and myelination could be impaired by cns infection , leading to different conditions , including major ( eg , lissencephaly and schizencephaly ) and minor ( eg , focal dysplasias ) brain malformations , and functional longitudinal cohorts of newborns from epidemic areas , involving systematic assessment of neurodevelopmental milestones , can help answering this issue . the first link between zikv infection and a neurological complication occurred in the zikv outbreak in french polynesia from october 2013 to march 2014.82 cao - lormeau et al83 reported 42 patients with gbs during this zikv outbreak , corresponding approximately to a 20-fold increase in the expected number of cases of gbs for that region . gbs is an acute autoimmune peripheral polyneuropathy characterized by the development of ascending motor weakness associated with variable degrees of cranial nerves palsy , sensory changes , and dysautonomia.84 the disease is self - limiting , reaching its nadir after 24 weeks of onset . depending on its severity , it can affect respiratory muscles , requiring artificial ventilation support . in the reported cases , most patients ( 88% ) had a previous history of a short - lasting viral syndrome characterized by fever , rash , arthralgia , and/or conjunctivitis , and all were positive for zikv serological tests . the gbs in these patients differed from the typical syndrome as it was marked by a fast progression to a nadir ( < 1 week ) and a short plateau phase . facial palsy was a common manifestation ( 64% ) , and one - third of patients required respiratory assistance . besides the combination of fast onset and fast recovery , patients lacked the typical demyelinating pattern of the disease , exhibiting the acute motor axonal neuropathy ( aman ) type.83 in contrast with non - zikv - related aman cases , the patients did not show the characteristic anti - ganglioside antibodies . the atypical presentation along the lack of aman - related antibodies cast doubt on the anti - glycolipid antibody role on disease pathogenesis.83,85 in this scenario , a direct effect of zikv can be implicated again . all patients in cao - lormeau et als83 series were treated with intravenous immunoglobulin , one of the standard treatments for gbs along with plasmapheresis.84 it remains to be defined whether the favorable clinical outcome observed in this study could be achieved with plasmapheresis and/or lack of specific treatment . preliminary reports from different latin american countries seem to corroborate the association between zikv and gbs.86 this also undermines an eventual role played by ethnic - related factors , such as human leukocyte antigen alleles , in post - zikv gbs.78 however , direct and/or indirect pathogenic roles for zikv must be proved . in this regard , animal models may be helpful , but so far no study has evaluated peripheral nerves lesion or dysfunction following zikv . it is also tempting to speculate whether zikv can be implicated in other autoimmune neurological diseases , as occurred with dengue virus.87 mcharles et al88 reported a case of acute myelitis possibly due to zikv infection . in 2016 , at the american academy of neurology meeting , doctor ferreira89 reported two brazilian patients with acute disseminated encephalomyelitis and zikv infection , calling great attention to this issue . to prevent unnecessary alarm , sporadic reports must be confirmed by careful epidemiological analysis , especially taking into consideration the concurrent circulation of other arboviruses , such as dengue . to date , there is no evidence of an increased rate of acute disseminated encephalomyelitis or related autoimmune conditions in regions facing zikv outbreak . there is a clear temporal association between the increased reporting of cases of microcephaly and of gbs and the zikv outbreak . however , there are several unanswered questions that must be investigated ( table 3 ) . for instance in addition , ongoing longitudinal cohort studies can show the long - term neurological and psychiatric consequences of congenital and after - birth zikv infection . from a personal perspective , as neither pharmacological treatment nor vaccines are available , prevention of zikv infection relies on protective measures against mosquito bites . further studies on zikv infection are urgently needed and may help the development of therapeutic strategies against zikv and other arboviruses , such as dengue and chikungunya .

before 2007 , zika virus ( zikv ) was generally considered as an arbovirus of low clinical relevance , causing a mild self - limiting febrile illness in tropical africa and southeast asia . currently , a large , ongoing outbreak of zikv that started in brazil in 2015 is spreading across the americas . virus infection during pregnancy has been potentially linked to congenital malformations , including microcephaly . in addition to congenital malformations , a temporal association between zikv infection and an increase in cases of guillain barr syndrome is currently being observed in several countries . the mechanisms underlying these neurological complications are still unknown . emerging evidence , mainly from in vitro studies , suggests that zikv may have direct effects on neuronal cells . the aim of this study was to critically review the literature available regarding the neurobiology of zikv and its potential neuropsychiatric manifestations .

chemical reaction networks ( crns ) and mass action kinetics are well studied formalisms for modelling biochemical systems @xcite . in recent years , crns have also been successfully used as a formal programming language for biochemical systems @xcite . there are two well established approaches for analyzing chemical networks : deterministic and stochastic @xcite . the deterministic approach models the kinetics of a crn as a system of ordinary differential equations ( odes ) and represents average behaviour , valid in the thermodynamic limit @xcite . the stochastic approach , on the other hand , is based on the chemical master equation ( cme ) and models the crn as a continuous - time markov chain ( ctmc ) @xcite . the stochastic behavior can be analyzed by stochastic simulation @xcite or by exhaustive probabilistic model checking of the ctmc , which can be performed , for example , by using prism @xcite . exhaustive analysis of the ctmc is able to find the best- and worst - case scenarios and is correct for any population size , but suffers from the state - space explosion problem @xcite and can only be used for relatively small systems . in contrast , deterministic methods are much more robust with respect to state - space explosion , but unable to represent stochastic fluctuations , which play a fundamental role when the system is not in thermodynamic equilibrium . * contributions . * in this paper we develop a novel approach for analysing the stochastic evolution of a crn based on the linear noise approximation ( lna ) of the cme . we formulate sel ( stochastic evolution logic ) , a probabilistic logic for crns that enables reasoning about probability , expectation and variance of linear combinations of populations of the species . examples of properties that can be specified in our logic are shown in example [ ex-1 ] . we propose an approximate model checking algorithm for the logic based on the lna and implement it in matlab and java . we demonstrate that the complexity of model checking is polynomial in the initial number of species and independent of the initial molecule counts , thus ameliorating state - space explosion . further , we show that model checking is exact when approaching the thermodynamic limit . though the algorithm may not be accurate for systems far from the deterministic limit , this generally happens when the populations are small , in which case the analysis can be performed by transient analysis of the induced ctmc @xcite . our approach is essential for crns that can not be analyzed by ( partial ) state space exploration , because of large or infinite state spaces . moreover , it is useful for a fast ( approximate ) stochastic characterization of crns , since solving the lna is much faster than solving the cme @xcite . we prove asymptotic correctness of lna - based model checking and show on four examples that it is still possible to obtain very good approximations even for small population systems , comparing with standard uniformisation @xcite and statistical model checking implemented in prism @xcite . * related work . * the closest work to ours is by bortolussi _ @xcite , which uses the central limit approximation ( cla ) ( essentially the same as the lna ) for checking restricted timed automata specifications , assuming a fixed population size . wolf _ @xcite develop a sliding window method to approximately verify infinite - state ctmcs , which applies to cases where most of the probability mass is concentrated in a confined region of the state space . recently , finite state projection algorithms ( fsp algorithms ) for the solution or approximation of the cme have been introduced @xcite . both methods apply to the induced ctmc , but require at least partial exploration of the state space , and are thus not immune to state - space explosion . * structure of the paper . * in section [ crn - sec ] we summarise the deterministic and stochastic modelling approaches for crns , and in section [ lna - sec ] we describe the linear noise approximation method . section [ logic - sec ] introduces the logic sel and the corresponding model checking algorithm based on the lna . in section [ results - sec ] we demonstrate our approach on four networks taken from the literature . section [ concl - sec ] concludes the paper . a _ chemical reaction network ( crn ) _ @xmath0 is a pair of finite sets , where @xmath1 is the set of _ chemical species _ and @xmath2 the set of reactions . @xmath3 denotes the size of the set of species . a _ reaction _ @xmath4 is a triple @xmath5 , where @xmath6 and @xmath7 . @xmath8 and @xmath9 represent the stoichiometry of reactants and products and @xmath10 is the coefficient associated to the rate of the reaction ; its dimension is @xmath11 . we often write reactions as @xmath12 instead of @xmath13^t,[0,2,0]^t , k_1 ) $ ] , where @xmath14 indicates the transpose of a vector . we define the _ net change _ associated to a reaction @xmath15 by @xmath16 . for example , for @xmath17 as above , we have @xmath18^t$ ] . we make the assumption that the system is well stirred , that is , the probability of the next reaction occurring between two molecules is independent of the location of those molecules . we consider fixed volume @xmath19 and temperature ; under these assumptions a _ configuration _ or _ state _ @xmath20 of the system is given by the number of molecules of each species . we define @xmath21=\frac{x}{n}$ ] , the vector of the species _ concentration _ in @xmath22 for a given @xmath23 , where @xmath24 is the volumetric factor , @xmath19 is the volume of the solution and @xmath25 is avogadro s number . the physical dimension of @xmath23 is @xmath26 , where @xmath27 indicates mole and @xmath28 is litre . given @xmath29 then @xmath30 represents the number of molecules of @xmath31 in @xmath22 and @xmath32\_x\in \mathbb{r}$ ] the concentration of @xmath31 in the same configuration . in some cases we elide @xmath22 , and we simply write @xmath33 and @xmath32 $ ] instead of @xmath34 and @xmath32\_x$ ] . they are related by @xmath32=\frac{\#\lambda_i}{n}$ ] . the dimension of @xmath32 $ ] is @xmath35 . the propensity @xmath36 of a reaction @xmath15 in terms of the number of molecules is a function of the current configuration of the system @xmath22 such that @xmath37 is the probability that a reaction event occurs in the next infinitesimal interval @xmath38 . in this paper we assume as valid the stochastic form of the law of mass action , so the propensity rates are proportional to the number of molecules that participate in the reaction @xcite . stochastic models consider the system in terms of numbers of molecules , while deterministic ones , generally , in terms of concentrations , and the relationship is as follows . for a reaction @xmath5 , given the configuration @xmath22 and @xmath39 , the @xmath40-th component of @xmath8 , then @xmath41\_x)}^{r_{\tau , i}}$ ] is the propensity function expressed in terms of concentrations as given by the deterministic law of mass action . it is possible to show that , for any order of reaction , @xmath42 if @xmath23 is sufficiently large @xcite . note that @xmath43 is independent of @xmath23 . in this paper we are interested only in finite time horizon , because of the problematic character of studying solutions of odes for infinite time horizon @xcite . r0.46 [ ex-1 ] consider the crn @xmath44 , where @xmath45 , with initial conditions @xmath46 , for a system with @xmath47 . figure [ fig : example ] plots the expectation and standard deviation of population sizes . we may wish to check if the maximum expected value of @xmath48 remains smaller than @xmath49 molecules during the first @xmath50 . however , the system is stochastic , so we also need to analyse whether the variance is limited enough when @xmath48 reaches the maximum . sometimes , analysis of first and second moments does not suffice , so it could be of interest to check the probability of some events , for instance , is the probability that , between @xmath51 and @xmath52 , @xmath53 greater than @xmath54 * deterministic semantics . * let @xmath0 be a crn . the deterministic model approximates the concentration of the species of the system over time as a set of autonomous polynomial first order differential equations : @xmath55 @xmath56 and @xmath57 . function @xmath58 describes the behaviour of the system as a set of deterministic equations assuming a continuous state - space semantics , therefore @xmath59 is the vector of the species concentrations at time @xmath60 . assuming @xmath61 , the initial condition is @xmath62 $ ] , expressed as a concentration . note that @xmath63 is lipschitz continuous , so @xmath64 exists and is unique @xcite . * * stochastic semantics.**crns are well represented by ctmcs , whose transient analysis can be performed via the chemical master equation ( cme ) @xcite . [ ctmc - defn ] given a crn @xmath0 and the volumetric factor @xmath23 , we define a time - homogeneous ctmc @xcite @xmath65 with state space @xmath66 . given @xmath67 , the initial configuration of the system , then @xmath68 . the transition rate from state @xmath69 to state @xmath70 is defined as @xmath71 . @xmath72 describes the stochastic evolution of molecular populations of each species at time @xmath60 . for @xmath73 , we define @xmath74 , where @xmath75 is the initial configuration . the cme describes the time evolution of @xmath76 as : @xmath77 the cme can be equivalently defined in terms of the infinitesimal generator matrix @xcite , which admits computing an approximation of the cme using , for example , fast adaptive uniformisation @xcite or the sliding window method @xcite . we also define the ctmc @xmath78 with state space @xmath79 . if @xmath80 \in s$ ] is the initial configuration , then @xmath81)=1.$ ] the transition rate from state @xmath82 $ ] to @xmath83 $ ] is defined as @xmath84,[x_j ] ) = \sum_{\{\tau \in r | [ x_j]=[x_i]+ \frac{v_{\tau}}{n}\ } } n\alpha_{c,\tau}(x_i)$ ] . @xmath85 is the random vector describing the system at time @xmath60 in terms of concentrations . in @xcite it is proved that @xmath86 \|=0 $ ] almost surely for every time @xmath60 . this explains the relationship between the two different semantics , where the deterministic solution can be viewed as a limit of the stochastic solution , valid when close enough to the thermodynamic limit . the solution of the cme can be computationally expensive , or even infeasible , because the set of reachable states can be huge or infinite . the linear noise approximation ( lna ) has been introduced by van kampen as a second order approximation of the system size expansion of the cme @xcite . since stochastic fluctuations depend on @xmath23 , and specifically , for average concentrations , are of the order of @xmath87 @xcite , to derive the expansion van kampen assumes that : @xmath88 where @xmath89 is the random vector , independent of @xmath23 , representing the stochastic fluctuations , @xmath90 is given by the solution of eqn and @xmath72 is the random vector of definition [ ctmc - defn ] . using this substitution in the system size expansion and then truncating at the second order , the probability distribution of @xmath91 is found to be given by the following linear fokker - plank equation @xcite : @xmath92 where @xmath93 and @xmath94 is the @xmath95th component of @xmath63 . the solution of eqn gives a gaussian process . for every time @xmath60 , @xmath91 has a multivariate normal distribution , whose expected value and covariance matrix are the solution of the following equations @xcite : @xmath96}{\mathrm d t } = j_f(\phi(t))e[z(t ) ] \label{eq : ev1}\ ] ] @xmath97 } { \mathrm d t } = j_f(\phi(t))c[z(t ) ] + c[z(t)]{j^t}_f(\phi(t))+g(\phi(t ) ) \label{eq : cov1}\ ] ] where @xmath98 is the jacobian of @xmath63 . we consider as initial conditions @xmath99=0 $ ] and @xmath100=0 $ ] . this means that @xmath101=0 $ ] for every @xmath60 . it is possible to justify the hypothesis noting that in the lowest order the cme expansion reduces to eqn , and with the following theorem by kurtz : @xcite[lna - thm ] consider the subset @xmath102 on which are defined the propensity functions @xmath43 . let @xmath103 be the random vector given by @xmath104 . suppose that @xmath105 for each compact @xmath106 , and that , for @xmath107 , @xmath108 , then @xmath103 converges in distribution to @xmath91 . the lna thus permits approximation of the probability distribution of @xmath72 with the probability distribution of @xmath109 . it is easy to show that @xmath110 has a gaussian distribution ; indeed , @xmath91 is gaussian distributed , and @xmath23 and @xmath90 are deterministic . to compute the lna it is necessary to solve @xmath111 first order differential equations , but the complexity is independent of the initial number of molecules of each species . therefore , one can avoid the exploration of the state space that methods based on uniformisation rely upon . theorem [ lna - thm ] alone only guarantees convergence in distribution . however , in @xcite , lna is derived as an approximation of the chemical langevin equation ( cle ) @xcite , rather than system size expansion . this shows that lna is valid for every real chemical system close enough to the thermodynamical limit , at least for a limited time . thus , lna is exact in the limit of high populations , but can also be used for small populations if the behaviour is not too far from the deterministic limit , taking into account the continuous nature of the approximation and gaussian assumptions on the noise @xcite . we have shown that @xmath76 can be approximated by @xmath112 , where @xmath110 has a multivariate gaussian distribution , so it is completely characterized by its expected value and covariance matrix , whose values are respectively @xmath113=n\phi(t)$ ] and @xmath114=n^{\frac{1}{2 } } c[z(t ) ] n^{\frac{1}{2}}=n c[z(t)]$ ] . since @xmath115 has a multivariate normal distribution then every linear combination of its components is normally distributed . therefore , given @xmath116 $ ] where @xmath117 , we can consider the random variable @xmath118 , which defines a linear combination of the species at time @xmath60 . for every @xmath60 , @xmath119 is a normal random variable , whose expected value and variance are @xmath120= be[{y^{n}}(t ) ] \label{eq : excom}\ ] ] @xmath121= bc[{y^{n}}(t)]b^t \label{eq : varcom}\ ] ] for a specific time @xmath122 , it is possible to calculate the probability that @xmath123 is within a set @xmath124 of closed , disjoint real intervals @xmath125 $ ] , where @xmath126 . this probability @xmath127 is given by @xmath128 \in i } \int\limits_{l_i}^{u_i } g(x|e[b{y^{n}(t_k ) } ] , c[b{y^{n}(t_k)}])dx \label{eq : combination}\ ] ] where @xmath129 is the gaussian distribution with expected value @xmath130 and covariance @xmath131 . we recall that it is possible to find numerical solution of eqn in constant time using the z table @xcite . consider the crn of example [ ex-1 ] , then we can obtain the probability that @xmath132 is at least @xmath133 at time @xmath134 by defining @xmath135 , \ , i'=\{[10,+\infty]\}$ ] and calculating @xmath136 . the following theorems are consequences of results in @xcite , which can be generalized for reactions with a finite number of reagents and products . they show asymptotic pointwise convergence of expected value , variance and probability . [ prob - thm ] let @xmath0 be a crn . suppose the solution of eqn is bounded , then , approaching the thermodynamic limit , for any finite instant of time @xmath137 @xmath138 where @xmath139 is the probability that @xmath140 is within @xmath124 at time @xmath137 . [ exp - var - thm ] suppose the solution of eqn is bounded , then , approaching the thermodynamic limit , for any finite instant of time @xmath122 @xmath141 - c[bx^{n}(t_k ) ] \| = 0\ ] ] @xmath142 -e[bx^{n}(t_k ) ] \| = 0.\ ] ] to solve the differential equations and , it is necessary to use a numerical method such as adaptive runge - kutta algorithm @xcite . this yields the solution for a finite set of sampling times @xmath143 \in \mathbb{r}^{|\sigma|}$ ] , where @xmath144 and @xmath145 is the sample size . assuming @xmath115 is separable , that is , it is possible to completely define the behavior of @xmath115 by only considering a countable number of points , we can calculate @xmath146 for any point in @xmath147 and if points are dense enough then this set exhaustively describes the probability that @xmath148 is within @xmath124 over time . this restriction is not a limitation since for any stochastic process there exists a separable modification of it @xcite . let @xmath149 be a crn with initial state @xmath75 , in a system of size @xmath23 . we now define the logic sel ( stochastic evolution logic ) which enables evaluation of the probability , variance and expectation of linear combinations of populations of the species of @xmath150 . the syntax of sel is given by @xmath151_{[t_1,t_2 ] } \quad |\quad q_{\sim v}[b]_{[t_1,t_2 ] } \quad |\quad \eta_1 \wedge \eta_2 \quad | \quad \eta_1 \vee \eta_2 \quad\ ] ] where @xmath152 , @xmath153 , @xmath154 $ ] , @xmath155 , @xmath156 , @xmath157 \ , | \ , l_i , u_i \in \mathbb{r } \cup [ + \infty,-\infty ] \ , \wedge [ l_i , u_i]\cap [ l_j , u_i]=\emptyset , \ , i \neq j\}$ ] and @xmath158 $ ] is a closed interval , with the constraint that @xmath159 and @xmath160 . if @xmath161 the interval reduces to a singleton . formulae @xmath162 describe global properties of the stochastic evolution of the system . @xmath163 specifies a linear combination of the species of @xmath150 and a set of intervals , where @xmath156 is the vector defining the linear combination and @xmath124 represents a set of disjoint closed real intervals . @xmath164_{[t_1,t_2]}$ ] is the probabilistic operator , which specifies the probability that the linear combination defined by @xmath165 falls within the range @xmath124 over the time interval @xmath158 $ ] . @xmath166 respectively yield the supremum and infimum of expected value and variance of the random variables associated to @xmath165 within the specified time interval . consider the crn of example [ ex-1 ] . checking if the variance of @xmath167 remains smaller than @xmath168 within @xmath169 $ ] can be expressed as @xmath170_{[t_j , t_k]}$ ] . another example is checking if , in the same interval , @xmath171 is at least @xmath172 or within @xmath173 $ ] , with @xmath174 , with probability greater than @xmath175 : . equivalently , instead of writing @xmath165 , we write directly the linear combination it defines . for example , in the latter case we have @xmath176,[k_2,\infty])]_{[t_j , t_k]}$ ] . given a crn @xmath0 with initial configuration @xmath75 in a system of fixed volumetric factor @xmath23 , its stochastic behaviour is described by the ctmc @xmath76 of definition [ ctmc - defn ] . we define a path of ctmc @xmath76 as a sequence @xmath177 where @xmath69 is a state and @xmath178 is the time spent in the state @xmath69 . a path is finite if there is a state @xmath179 that is absorbing . @xmath180 is the state of the path at time @xmath60 . @xmath181 is the set of all ( finite and infinite ) paths of the ctmc starting in @xmath75 . we work with the standard probability measure @xmath182 over paths @xmath181 defined using cylinder sets @xcite . we first define when a path @xmath183 satisfies @xmath184 at time @xmath60 @xmath185 \in i \,.\ , l_i \leq b(\omega \otimes t ) \leq u_i .\ ] ] note that @xmath186 is well defined because @xmath187 . we now define @xmath188 , then if the time interval is a singleton the satisfaction relation for the probabilistic operator is @xmath189_{[t_1,t_1 ] } \quad \leftrightarrow \quad pr^{x^n}_{b , i } ( t_1 ) \sim p\ ] ] instead , for @xmath190 we have @xmath189_{[t_1,t_2 ] } \quad \leftrightarrow \quad \frac{1}{t_2-t_1 } \int_{t_1}^{t_2 } pr^{x^n}_{b , i } ( t)\,\mathrm{d}t \sim p\ ] ] @xmath191 is the probability of the set of paths of @xmath76 such that the linear combination of the species defined by @xmath165 falls within @xmath124 . it is well defined since we have previously defined the probability measure @xmath182 on @xmath192 . to define the satisfaction relation of the probabilistic operator we simply take the average value of @xmath191 during the interval @xmath158 $ ] . for the remaining operators the satisfaction relation is defined as @xmath193_{[t_1,t_2 ] } \quad \leftrightarrow \quad sup(c[b(x^n)],[t_1,t_2 ] ) \sim v\ ] ] @xmath194_{[t_1,t_2 ] } \quad \leftrightarrow \quad inf(c[b(x^n)],[t_1,t_2 ] ) \sim v\ ] ] @xmath195_{[t_1,t_2 ] } \quad \leftrightarrow \quad sup(e[b(x^n)],[t_1,t_2 ] ) \sim v\ ] ] @xmath196_{[t_1,t_2 ] } \quad \leftrightarrow \quad inf(e[b(x^n)],[t_1,t_2 ] ) \sim v\ ] ] @xmath197 @xmath198 @xmath199)$ ] and @xmath200)$ ] respectively denote the infimum and supremum within @xmath158 $ ] . stochastic model checking of crns is usually achieved by transient analysis of the ctmc @xmath76 @xcite , which involves solving the cme and thus suffers from the state - space explosion problem . we propose an approximate model checking algorithm based on lna . the inputs are a sel formula @xmath162 , the stochastic process @xmath76 induced by the crn and initial state @xmath75 . the output is @xmath201 in case the formula is verified , and otherwise @xmath202 . the algorithm proceeds by induction on the structure of formula @xmath162 , successively computing whether each subformula is satisfied or not . we assume that eqn and are solved numerically where @xmath147 is the finite set of sample points on which their solution is defined and that @xmath203 , initial time , and @xmath204 , final time , are always sampling points . to evaluate @xmath205_{[t_1,t_2]}$ ] we construct the function @xmath206 for @xmath207 ( alternatively , can be constructed as the interpolation of the values of @xmath146 over @xmath147 points ) . @xmath208 is integrable on @xmath209 . theorem [ prob - thm ] guarantees the pointwise correctness of @xmath208 and its integrability allows us to compute the following approximation , then compare to threshold @xmath210 to decide the truth value . if @xmath211 then @xmath212 else if @xmath161 then @xmath213 . to evaluate @xmath214,[t_1,t_2 ] ) $ ] , @xmath215,[t_1,t_2])$ ] , @xmath216,[t_1,t_2 ] ) $ ] and @xmath217,[t_1,t_2])$ ] we use the lna , namely , compute the expected value and variance of eqn and . theorem [ exp - var - thm ] guarantees the quality of the approximation . we can now compute the following approximations , then compare to the threshold @xmath218 : @xmath219,[t_1,t_2])\approx max \ { c[by^{n}(t_k ) ] \ , | \ , ( t_k \in \sigma \wedge t_1\leq t_k \leq t_2 ) \vee ( t_k \in l_{[t_1,t_2 ] } ) \}\ ] ] @xmath220,[t_1,t_2])\approx min \ { c[by^{n}(t_k ) ] \ , | \ , ( t_k \in \sigma \wedge t_1\leq t_k \leq t_2 ) \vee ( t_k \in l_{[t_1,t_2 ] } ) \}\ ] ] and similarly for the expected value . t_i \in \sigma \ , \ , \wedge \,\ , \nexists t_j \in \sigma$ ] @xmath222 @xmath223 @xmath224 ensures that for any time interval there is at least one sampling point , even if the interval is a singleton . note that , for each sub - formula , the algorithm involves the calculation of some quantity , so one can define a quantitative semantics for sel as in @xcite . lna - based model checking can also be used for systems far from the thermodynamic limit , at a cost of some loss of precision . lna assumes continuous state space , and it is not possible to justify this assumption for very small populations . however , if the distributions of interest are not multi - modal and the noise term is finite and approximated by a gaussian distribution , then lna gives very good approximation even for quite small systems . it is clear that model checking accuracy increases as @xmath23 grows . we emphasise that the model checking algorithm we have presented is also able to handle crns whose stochastic semantics is an infinite ctmc , which occur frequently in biological models . the time complexity for model checking formula @xmath162 against a crn @xmath0 is linear in @xmath225 . in the worst case , analysis of a single operator requires the solution of @xmath111 polynomial differential equations for a bounded time . however , an efficient implementation can solve the @xmath111 odes only once for the interval @xmath226 $ ] , and then reuse this result for every operator , where @xmath204 is the greatest ( finite ) time of interest . note that odes are solved in terms of concentrations ( a value between @xmath227 and @xmath228 by convention ) , ensuring independence of the number of molecules of each species , although stiffness can slow down the solution of the lna . we implemented the methods in a framework based on matlab and java . the experiments were run on an intel dual core @xmath229 machine with @xmath230 gb of ram . to solve the differential equations , we use @xmath231 @xmath232 , a variable step runge - kutta algorithm . we employ lna - based model checking for the analysis of four biological reaction networks : a phosphorelay network @xcite , a gene expression model @xcite , the fgf pathway @xcite and the gw network @xcite . for every network , the crn and parameters have been taken from the referenced papers . we coded the same crns in prism in order to compare accuracy and time of execution with standard uniformisation of the cme @xcite and statistical model checking ( smc ) techniques ( confidence interval method ) as implemented in prism . for the fgf and gw case studies , we can not use global analysis nor smc , because the state space is too large for direct analysis , and smc requires many time - consuming simulations to obtain good accuracy . * phosphorelay network . * we consider a three - layer phosphorelay network whose structure is derived from @xcite . each layer @xmath233 can be found in phosphorylate form @xmath234 . we consider the initial condition @xmath235 , where @xmath236 . then we analyse the ligand @xmath165 , whose initial condition is @xmath237 . we are interested in checking the following sel property : @xmath238_{[0,100]}\wedge p_{>0.98}[(\#l3p-\#l1p),[0,+\infty]]_{[300,600]}\ ] ] which is verified if , in the first interval , the probability that @xmath239 is greater than @xmath240 is @xmath241 and if , between @xmath242 and @xmath243 , with probability @xmath244 , @xmath240 is greater than @xmath239 . we evaluate this formula in three different initial conditions , firstly @xmath245 and @xmath246 , then @xmath247 and @xmath248 , and finally @xmath249 and @xmath250 , so the same concentration but different numbers of molecules . in all cases , the lna - based model checking evaluates the formula as true . to understand the quality of the approximation , we check the following quantitative formula @xmath251)]_{[t , t]}$ ] for @xmath252 $ ] ( in our implementation @xmath253 gives the quantitity calculated by model checking the operator ) . we compare the results with the evaluation of the corresponding csl formula using standard uniformisation ( @xmath254 ) with error @xmath255 @xcite . the following table shows the results . @xmath256 is the maximum error computed by lna - based approach compared to standard uniformisation and @xmath257 is the average error ; @xmath258 stands for execution time . [ cols="<,<,<,<,<",options="header " , ] * fgf . * we consider the model of fibroblast growth factor ( fgf ) signalling pathway developed in @xcite composed of more than @xmath259 reactions and species . we consider the system with initially 105 molecules for species with non - zero initial concentration . analysis of the model reveals that the phosphorylated form of @xmath260 can bind the protein @xmath261 , and then this new complex , @xmath261:@xmath260 , can relocate out . we want to check if the expected value of @xmath262:@xmath260 during the first @xmath263 seconds reaches a maximum value greater than @xmath264 . we do that by checking the property @xmath265:@xmath266_{[0,3000]}$ ] . the formula evaluates to true , and in figure [ fig : sto ] we analyze the expected value and standard deviation of @xmath267:@xmath260 . we obtain these values directly from the logic considering the quantitative interpretation of @xmath268:@xmath266_{[t , t]}$ ] and @xmath269:@xmath266_{[t , t]}$ ] for @xmath270 $ ] . it is possible to see that , after an initial peak , relocation causes exponential decay . r0.54 in the same figure we show a single stochastic simulation of the system for the same initial conditions , confirming our evaluation . moreover , the approximation can be justified theoretically . @xmath262:@xmath260 converges to zero necessarily and this demonstrates the unimodality of the distribution of the species ; we note that the variance is finite , so eqn holds . * dna strand displacement of gw network * gw is a network related to the g2-m cell cycle switch @xcite . under particular initial conditions , it has been shown that gw can emulate the approximate majority algorithm @xcite . here , we consider the two - domain dna strand - displacement implementation of gw @xcite . the corresponding crn is composed of @xmath271 species and @xmath272 reactions . for our analysis the species of interest are @xmath2 and @xmath273 , whose initial conditions are @xmath274 and @xmath275 ; initial conditions of other species are taken from the referenced papers . we check the property @xmath276_{[6000,35000]}$ ] for a system of size @xmath277 , which is verified as true in @xmath278 minutes . we presented a novel probabilistic logic for analysing stochastic behaviour of crns and proposed an approximate model checking algorithm based on the lna of the cme . we have demonstrated on four non - trivial examples that lna - based model checking enables analysis of crns with hundreds of species , and even infinite ctmcs , at a cost of some loss of accuracy . it would be interesting to find bounds on the approximation error when the system is far from the thermodynamic limit . however , the error is not only dependent on the value of @xmath23 , but also on the structure of the crn , the rates , and the property . as future work , we plan to improve the accuracy of the method near critical points similarly to the approach of @xcite , and to extend the logic with more expressive temporal operators in the style of csl @xcite . we also intend to release a software tool based on lbs @xcite . the authors would like to thank luca bortolussi for helpful discussions . @xmath279 is riemann integrable on @xmath209 . @xmath208 is a bounded function with at most @xmath280 discontinuities , where @xmath281 . therefore , the set of discontinuities is a countable set , and countable sets have measure @xmath227 . therefore , the conditions of the lebesgue criterion for integrability holds . this concludes the proof .

stochastic evolution of chemical reactions networks ( crns ) over time is usually analysed through solving the chemical master equation ( cme ) or performing extensive simulations . analysing stochasticity is often needed , particularly when some molecules occur in low numbers . unfortunately , both approaches become infeasible if the system is complex and/or it can not be ensured that initial populations are small . we develop a probabilistic logic for crns that enables stochastic analysis of the evolution of populations of molecular species . we present an approximate model checking algorithm based on the linear noise approximation ( lna ) of the cme , whose computational complexity is independent of the population size of each species and polynomial in the number of different species . the algorithm requires the solution of first order polynomial differential equations . we prove that our approach is valid for any crn close enough to the thermodynamical limit . however , we show on four case studies that it can still provide good approximation even for low molecule counts . our approach enables rigorous analysis of crns that are not analyzable by solving the cme , but are far from the deterministic limit . moreover , it can be used for a fast approximate stochastic characterization of a crn .

however endoscopy is the golden standard of gastrointestinal system examination and treatment of gastrointestinal system diseases , painfulness and discomfort of procedure makes the process for both appliers and the ones who was applied ( 1 , 2 ) . as a result , anxiety is a common problem in patients undergoing interventional medical procedures . because of this reason sedation for upper gastrointestinal endoscopy and colonoscopy not only improves patient tolerance and satisfaction but also increases the willingness of patients to return for repeated procedures ( 3 ) . despite this , gastrointestinal endoscopy and colonoscopy are still accepted as invasive procedures with the potential for discomfort , embarrassment and disappointment related to unexpected findings . these concerns can result in anxiety that unfavorably decreases patient cooperation and satisfaction with the gastroscopic or colonoscopic procedure ( 4 ) . it was reported that features such as age and gender may effect the anxiety ( 5 ) . different types of anxiety scales were preferred in patients who will undergo upper gastrointestinal endoscopy and colonoscopy . determination , alleviation and elimination of anxiety is important for not just unwanted and discomfortable conditions , it is also important that anxiety extends , complicate the procedure and increases complications ( 8) . for the alleviation of anxiety , many techniques such as information and music playback before the various invasive procedures has been tried ( 9 , 10 ) . but , it is important for the efficiency of these techniques to determinate the anxiety levels and potential risk groups for anxiety . aim of this study was to assess the level of anxiety in patients who will undergo upper gastrointestinal endoscopy and colonscopy , and the relationship between anxiety and individual and social features of these patients . institutional ethics committee approval and written consent from the patients were obtained for the study . five hundred patients between the ages of 18 - 80 years , asa physical status i , ii and iii , scheduled to undergo sedation for elective upper gastrointestinal endoscopy and colonoscopy were studied . patients were excluded if they were declined conscious sedation or had previously undergone sedation for elective upper gastrointestinal endoscopy and colonoscopy . other exclusion criteria included : patient age below 18 or above 80 years , physical inability to participate , hearing problems due to any cause , any overt or borderline psychiatric illnesses , senile dementia and treatment with anxiolytic medication in the last 72 hours prior to examination . beck anxiety inventory ( 11 ) was administered to each patient before brought to the endoscopy room . this is a 21-item self - report questionnaire in which the respondent is asked to rate how much each symptom has bothered him / her over the week leading up to the procedures . the symptoms are rated on a four - point scale , ranging from not at all to severely . the values for each item are summed yielding a total score ranging between 0 and 63 points . a beck score of 0 - 7 represents a minimal level of anxiety , 8 - 15 mild , 16 - 25 moderate and 26 - 63 severe anxiety . demographic data of patients including age , gender , comorbidities , height , weight , body mass index and educational status , were collected . parametric data were tested with student s t test and one - way anova presented as median , interquartile range ( iqr ) and range , accordingly . categorical data were analyzed with the two - tailed pearson s x2 test and are given as numbers and proportions . values are expressed as median ( iqr [ range ] ) , number or number ( proportion ) . values are as median ( iqr [ range ] ) , number or number ( proportion ) . comparison of beck anxiety inventory scores and demographic data by gender are summarized in table 2 . values are as median ( iqr [ range ] ) , number or number ( proportion ) . * minimal , mild , moderate , severe . * * primary - high school : university and upper * * * upper gi endoscopy : colonoscopy : both beck anxiety inventory scores were significantly lower in males compared to females [ respectively , 4.00 ( 4.39 - 5.89 [ 0 - 37 ] ) , 9.00 ( 9.15 - 10.85 [ 0 - 57 ] ) p<0.001 ] . anxiety levels ( minimal , mild , moderate , severe ) were significantly lower in males compared to females too [ respectively , 132 ( % 73.3 ) : 41 ( % 22.8 ) : 6 ( % 3.3 ) : 1 ( % 0.6 ) , 142 ( % 44.4 ) : 112 ( % 35.5 ) : 49 ( % 15.3 ) : 17 ( % 5.3 ) p<0.001 ] . comparison of beck anxiety inventory scores and demographic data by comorbidity are summarized in table 3 . beck anxiety inventory scores were significantly lower in patients with no comorbidity compared to patients with comorbidity [ respectively , 6.00 ( 6.60 - 8.13 [ 0 - 57 ] ) , 9.00 ( 8.97 - 11.20 [ 0 - 32 ] ) p<0.001 ] . anxiety levels ( minimal , mild , moderate , severe ) were significantly lower in patients with no comorbidity compared to patients with comorbidity too [ respectively , 203 ( % 60.2 ) : 100 ( % 29.7 ) : 23 ( % 6.8 ) : 11 ( % 3.3 ) , 71 ( % 43.6 ) : 53 ( % 32.5 ) : 32 ( % 19.6 ) : 7 ( % 4.3 ) p<0.001 ] . comparison of beck anxiety inventory scores and demographic data by educational status are summarized in table 4 . values are as median ( iqr [ range ] ) , number or number ( proportion ) . * minimal , mild , moderate , severe . * * primary - high school : university and upper * * * upper gi endoscopy : colonoscopy : both comparison of anxiety scores and demographic data by educational status . values are as median ( iqr [ range ] ) , number or number ( proportion ) . * minimal , mild , moderate , severe . * * upper gi endoscopy : colonoscopy : both beck anxiety inventory scores were significantly lower in patients educational status university and upper compared to patients educational status primary - high school [ respectively , 7.00 ( 7.81 - 9.19 [ 0 - 57 ] ) , 4.00 ( 4.67 - 7.63 [ 0 - 22 ] ) p=0.026 ] . there were no significant difference between anxiety levels compared to educational status groups [ respectively , 238 ( % 53.2 ) : 141 ( % 31.5 ) : 50 ( % 11.2 ) : 18 ( % 4.0 ) , 36 ( % 67.9 ) : 12 ( % 22.6 ) : 5 ( % 9.4 ) : 0 ( % 0.0 ) p=147 ] . comparison of beck anxiety inventory scores and demographic data by procedure are summarized in table 5 . there were no significant difference between anxiety inventory scores compared to procedures [ respectively , 7.00 ( 7.68 - 9.20 [ 0 - 57 ] ) , 5.00 ( 5.46 - 8.11 [ 0 - 24 ] ) , 9.00 ( 7.21 - 11.19 [ 0 - 22 ] ) p=0.144 ] . there were no significant difference between anxiety levels compared to procedures too [ respectively , 210 ( % 53.7 ) : 121 ( % 30.9 ) : 42 ( % 10.7 ) : 18 ( % 4.6 ) , 50 ( % 67.6 ) : 17 ( % 23.0 ) : 7 ( % 9.5 ) : 0 ( % 0.0 ) , 14 ( % 40.0 ) : 15 ( % 42.9 ) : 6 ( % 17.1 ) : 0 ( % 0.0 ) p=0.054 ] . according to comparison of anxiety scores and demographic data by age groups there were no significant difference between beck anxiety inventory scores compared to age groups [ respectively , 7.00 ( 7.81 - 9.19 [ 0 - 57 ] ) , 4.00 ( 4.67 - 7.63 [ 0 - 22 ] ) p=0.301 ] . there were no significant difference between anxiety levels compared to age groups [ respectively , 139 ( % 58.9 ) : 68 ( % 28.8 ) : 20 ( % 8.5 ) : 9 ( % 3.8 ) , 135 ( % 51.1 ) : 85 ( % 32.2 ) : 35 ( % 13.3 ) : 9 ( % 3.4 ) p=0.214 ] . values are as median ( iqr [ range ] ) , number or number ( proportion ) . * minimal , mild , moderate , severe . * * primary - high school : university and upper in the present study the effect of age , gender , comorbidity , education status and procedure type to preprocedural anxiety scores who will undergo elective upper gastrointestinal endoscopy and colonoscopy under sedation , were evaluated . while gender , comorbidity and education status effect the anxiety scores , procedure type and age were presented not effected the anxiety scores . when the results of the present study were evaluated , [ minimal ( % 54.8 ) , mild ( % 30.6 ) , moderate ( % 11.0 ) , severe ( % 3.6 ) ] anxiety levels are correlated to clinical study that was performed in 135 patients who underwent colonoscopy under sedation ( 12 ) . in a study which was performed in patients who underwent gastrointestinal endoscopy under sedation as reason of this state it was denoted that older subjects generally had a limited understanding of the procedure and showed less anxiety about the procedure . however mean age of older patients in our study were very high than this study , in our study there were no difference between young and old patients in anxiety scores adversely to the study . we think the detailed preprocedural information given by the endoscopist is the reason of this state . in an other study about this subject in literature , it was reported that preprocedural anxiety scores were not effected by age ( 14 ) . higher preprocedural anxiety scores have been exhibited in women than in men who will undergo upper gastrointestinal endoscopy vs colonoscopy ( 13 , 15 - 17 ) . . the results of our study exhibited higher preprocedural anxiety scores in patients who has comorbidities . in literature there is no study or data about this subject that support or suggest otherwise , but it is acceptable that comorbidity also may cause anxiety who will not undergo any procedure too . education status is a possible reason for preprocedural anxiety . in a study which was performed in patients who underwent upper gastrointestinal endoscopy and colonoscopy under sedation , it was reported that there were no relationship between education status and preprocedural anxiety . in our study , however beck anxiety inventory scores 7.00 ( 7.81 - 9.19 [ 0 - 57 ] ) were statistically higher in primary - high school group , these scores were not significant in clinically . thus it was seen these scores are clinically insignificant by anxiety levels were not different when educational status were compared . as similar with our study results there were no difference in preprocedural anxiety determined in studies which compared preprocedural anxiety scores in different types of procedures ( upper gastrointestinal endoscopy and colonoscopy ) ( 14 - 16 , 18 ) . further more , there were 3 types of procedure performed in our study ( upper gastrointestinal endoscopy , colonoscopy and both ) , not 2 types ( upper gastrointestinal endoscopy and colonoscopy ) . there were no statistically difference detected in preprocedural anxiety scores and levels when these 3 types are compared . although sedation demand for upper gastrointestinal endoscopy and colonoscopy increased it was seen inadequate to reduce the preprocedural anxiety levels . further , presence of comorbidity and gender must be considered , because to determine the factors that effect preprocedural anxiety and well assessment of these factors are important . however the effect of age , educational status and procedure type on preprocedural anxiety could not shown in our study , further studies are needed because inadequacy of literature .

background : anxiety is a common preprocedural problem and during processing especially in interventional medical processes.aim:aim of this study was to assess the level of anxiety in patients who will undergo upper gastrointestinal endoscopy and coloscopy.methods:five hundred patients scheduled to undergo sedation for elective upper gastrointestinal endoscopy and colonoscopy were studied . beck anxiety inventory ( bai ) was administered to each patient before brought to the endoscopy room . demographic data of patients were collected.results:bai scores and anxiety levels were significantly lower in ; males compared to females , patients with no comorbidity compared to patients with comorbidity ( both p values < 0.001 ) . bai scores were significantly lower in patients educational status university and upper compared to patients educational status primary - high school ( p=0.026 ) . there were no significant difference between bai and anxiety levels compared to procedures ( respectively , p=0.144 p=0.054 ) . there were no significant difference between bai scores and anxiety levels compared to age groups ( respectively , p=0.301 p=0.214).conclusions : we think that level of anxiety in patients who will undergo upper gastrointestinal endoscopy and colonoscopy was effected by presence of comorbidities and gender but was not effected by features such as age , procedure type and educational status .

uterine rupture has continued to be a catastrophic feature of obstetrics practice in the low - resource settings in countries like nigeria.1234 it is life threatening to both the mother and the foetus.5678 the lack of access to emergency obstetric care facilities and the low utilization of modern maternal services are the identified causes of higher incidence of uterine rupture in developing countries than in the developed countries.389 most reports have identified not registering for antenatal care as a risk factor for uterine rupture.341011 maternal case fatality rates as high as 10.3% and 16.0% have been reported , while the foetal mortality rates are even much higher at 70%12 and 90%.13141516 however , mothers that escape mortality are left to suffer morbidities such as anaemia , wound and genital sepsis and burst abdomen.715 others , in addition , lose their uterus and compromise their future fertility.15 against this backdrop , this study aims to determine the incidence , predisposing risk factors , treatment options and maternal and foetal outcomes of patients with ruptured uterus in nnamdi azikiwe university teaching hospital , nnewi , nigeria . this study aims to assist in planning interventions that will reduce the incidence , morbidity and mortality associated with uterine rupture . this is a cross - sectional study with retrolective study of cases of uterine rupture in nnamdi azikiwe university teaching hospital between 1st january , 2001 and 31st december , 2010 . the names and hospital number of all the cases of uterine rupture in the hospital over a 10-year period were obtained from the labour ward and operating theatre registers . a thorough scrutiny of the delivery records of the obstetric unit as well the records of the medical records department and special care baby unit ( scbu ) of the hospital was done to identify these patients by checking on their names , case file numbers and their diagnosis at the time of presentation in the labour ward and subsequent management of their babies on admission to scbu . of all the 5,585 deliveries during the study period , 47 cases of uterine rupture were recorded . only 43 case files ( 91.5% ) were retrieved from the medical records department of the hospital and were used subsequently for analysis . the information on the age , parity , number of living children , booking status , risk factors and the type / extent of rupture were extracted . the other information extracted included site of rupture , type of surgery performed , maternal and foetal outcome and the length of hospital admission . the rupture is described as traumatic if oxytocin infusion was used for induction or augumentation of labour . data analysis was done using epi info 2008 ( v 3.5.1 ; epi info , centers for disease control and prevention , atlanta , ga ) . during the study period , there were a total of 47 cases of uterine rupture out of 5,585 deliveries , giving an incidence of 1 in 119 deliveries or 0.84% or 8.4 per 1000 deliveries . the mean age of the patients was 31.2 years 4.3 , while the majority ( 34 , 74.5% ) were 30 years . however , none of the patients was aged 20 years and two of them were aged > 35 years . the majority of the patients ( 14 , 32.6% ) were para 1 and 2 , while the remaining ( 6 , 14.0% ) were para 3 and 4 . three of the patients were grand multiparous ( parity 5 ) and none of the patients was nulliparous ( parity = 0 ) . only 13 ( 30.2% ) of the patients were registered for antenatal care ( booked ) . the majority of the patients ( 30 , 63.8% ) did not register for their antenatal care ( unbooked ) . majority of the patients ( 13 , 30.2% ) had no living child , 11 ( 25.6% ) and seven ( 16.3% ) had two and one living children , respectively . table 1 shows the type of uterine rupture and the factors attributable to the rupture . complete ruptures were seen in 38 patients ( 88.4% ) , while incomplete rupture occurred in only five patients ( 11.6% ) . aetiological factors attributable to uterine rupture table 2 shows the type of surgery performed at laparotomy for the patients who had uterine rupture . the majority ( 18 , 41.9% ) of the rupture occurred at the lateral uterine segment , followed by 15 ( 34.8% ) and 10 ( 23.3% ) at the anterior and posterior segments respectively . some patients had more than one site of uterine segment involved in the rupture and up to seven ( 16.3% ) patients had uterine rupture along the previous lower segment scar . types of surgery performed in patients with uterine rupture over a 10-year period there were seven maternal deaths out of the 43 cases reviewed , giving a case fatality rate of 16.3% . all but one of the maternal deaths occurred in the unbooked patients ; the booked patient involved had hyperstimulation from misoprostol , which was used for cervical ripening . there were 38 perinatal deaths given a perinatal mortality rate of 88.4% or 884 in 1000 deliveries . in the present study , the overall incidence of uterine rupture was 1 in 119 deliveries or 0.84% . this figure was higher than that in several reports from other parts of nigeria , such as 0.33% in ilorin,16 0.4% in ife,17 0.5% in lagos,5 0.53% in enugu14 and 0.72% in ibadan.15 the lowest incidence was found in the western world , with rates of 0.4 per 1000 being recorded.15 a number of factors may be responsible for the wide variation in the incidence of uterine rupture in nigeria . these include the obstetric risk factors ( previous caesarean section scar , not registering of antenatal care ) operative in a given population , the capability of obstetric personnel , the facilities available for obstetric care of the patients and the utilization of the facilities by the resident population.615 unfortunately , in nigeria , most of the factors still operate and downturn of the economy has not helped matters . people wittingly or unwittingly have allowed spiritual churches to attend to them in labour at little or no cost.181920 the trend of trial of vaginal birth after caesarean section ( vbac ) and obstetric manoeuvres in breech presentation may be contributory . it is not surprising that the majority ( > 60% ) of the patients with uterine rupture was unbooked and had not availed themselves of available obstetric services in the index pregnancy . this figure compares favourably with reports in various parts of nigeria and africa,5681117 supporting the notion that lack of antenatal care was associated with increased maternal and foetal morbidity in uterine rupture.341011 the age and parity distributions were similar to several reports in various part of the country . incidence of uterine rupture was highest in para 1 and para 2 groups and generally occurred between the para 1 and para 4 groups . this is similar to previous studies in lagos,5 ile - ife,17 enugu14 and ibadan,15 all in nigeria . the nulliparous uterus has been described as being virtually immune to rupture,21 especially before the onset of contractions . none of the patients in our study was nulliparous , which supports the above saying ; however , other studies in other parts of nigeria have found uterine rupture in nulliparous and grand multiparous women.1415 isolated case reports of uterine rupture in the primigravida have been described in association with connective tissue disease,22 chronic steroid use22 and cocaine misuse.23 in the majority of cases ( 72.1% ) , traumatic rupture contributed to these cases of uterine rupture . this resulted from the use of oxytocin infusion in both the scarred and unscarred uteri . induction of labour either with oxytocin or prostaglandins is an independent risk factor for uterine rupture in women with scarred uterus.24252627 application of fundal pressure in the second stage of labour was contributory . the incidence of iatrogenic rupture has been directly linked to the number of skilled personnel attending to the patients.14 spontaneous rupture occurred in only 12 ( 27.9% ) of the patients similar to report in enugu,14 but different from reports from other subregions and countries where its contribution was higher than in iatrogenic uterine rupture.1628 the overall incidence of caesarean section in the study centre in 2008 was 26.9%.29 this incidence appears to be increasing since then . this means that this will likely influence the epidemiology of uterine rupture in the future as some patients who had prior caesarean section may have uterine rupture based on extrapolation in the present study . some of which might fail to present to hospitals in their subsequent pregnancy , only to present when they had already ruptured their uterus . complete uterine rupture in which the foetus was already extruded into the peritoneal cavity was observed in most cases ( 88.4% ) . in these cases , majority ( 90.7% ) of the patients had uterine repair [ ( with or without bilateral tubal ligation ( btl ) ] . uterine repair alone was the commonest procedure probably because majority of the women were in their lower parity and had desire for more children . the findings of greater number of subtotal hysterectomy performed over total hysterectomy have been similarly reported in various regions in nigeria.58141517 two patients in this study had previous uterine rupture . although most women with a previous uterine rupture with meticulous tertiary level antenatal care may have a favourable outcome in subsequent pregnancies , child birth after uterine rupture is not to be recommended routinely.30 the maternal mortality of 16.3% obtained in this study was high and compares with 17.0% in ile - ife,17 17.5% in lagos5 and 17.9% in ibadan , all in nigeria . some other regions recorded lower fatality rates , including 10% in malawi,12 11% in sokoto , nigeria31 and 13 % in enugu , nigeria.14 delay in arrival and receiving emergency obstetric care ( emoc ) were the main reasons for the high case fatality in uterine rupture.831 the average hospital stay was 10.3 days . this was similar to a report from ibadan,15 where 96% of the patients spent more than 7 days in the hospital . this is noteworthy because prolonged admission , especially without early ambulation , increases post - operative morbidity and adds to the economic loss to the patient . the main weakness is that the reasons why majority of the paturients were unbooked could not be explained by our study . cultures and religious beliefs may appear to positively relate to higher rates of uterine rupture in our study . furthermore , psychosocial factors such as ignorance and socioeconomic factors such as income and social class could have explained more variance in the uterine rupture , which we did not evaluate in the present study . another limitation is the retrolective study design , where some data could have been missed . uterine rupture constitutes a major obstetric emergency in the study hospital and has potentially catastrophic implications for the mother and the baby . caesarean section rates are rising and hence a concomitant rise in incidence of uterine rupture is expected . there is a dire need for antenatal care and skilled attendants at delivery , and this should be emphasized through health education . patients with scarred uterus must be adequately counselled on the need for hospital delivery in their subsequent pregnancy . assessment of risk factors for uterine rupture is important both antenatally and in the intrapartum period . careful selection of patients for trial of vbac and adequate training of doctors and midwives to detect the early warning symptoms and signs of uterine rupture is advocated . caution should be exercised with the use of oxytocics , especially during augmentation of poorly progressing multiparous women and those with prior caesarean section . finally , most of the cases of uterine rupture are preventable . strategies should be aimed at improving the access to healthcare services and provision of resources to deal with obstetric emergencies . timely diagnosis and institution of swift and appropriate interventions would help save the lives of mothers and their babies .

background : uterine rupture has continued to be a catastrophic feature of obstetric practice especially in the low - resource settings . this study determined the incidence , predisposing factors , treatment options and feto - maternal outcome of ruptured uterus.materials and methods : a 10-year retrolective study of all cases of uterine ruptures that were managed in nnamdi azikiwe university teaching hospital , nnewi , nigeria between 1st january , 2001 and 31st december , 2010 was undertaken . the proforma was initially used for data collection , which was transferred to a data sheet before entering them into the epi - info software . analysis was done using epi info 2008 ( version 3.5.1).results : out of 5,585 deliveries over the study period , 47 had uterine rupture , giving an incidence of 0.84% or 1 in 119 deliveries . all the patients were multiparous and majority ( 63.8% ) was unbooked . traumatic ( iatrogenic ) rupture predominated ( 72.1% ) . uterine repair with ( 55.8% ) or without ( 34.9% ) bilateral tubal ligation was the commonest surgery performed . case fatality rate was 16.3% , while the perinatal mortality rate was 88.4% . average duration of hospitalization following uterine rupture was 10.3 days.conclusion:uterine rupture constituted a major obstetric emergency in the study hospital and its environs . the incidence , maternal and perinatal mortalities were high . the traumatic / iatrogenic ruptures constituted the majority of cases , hence , majority of the cases are preventable . there is therefore a dire need for education of our women on health - related issues , utilization of available health facilities , adequate supervision of labour and provision of facilities for emergency obstetric care .

SECTION 1. SHORT TITLE. This Act may be cited as the ``National Foundation on Fitness, Sports, and Nutrition Establishment Act''. SEC. 2. ESTABLISHMENT AND PURPOSE OF FOUNDATION. (a) Establishment.--There is established the National Foundation on Fitness, Sports, and Nutrition (hereinafter in this Act referred to as the ``Foundation''). The Foundation is a charitable and nonprofit corporation and is not an agency or establishment of the United States. (b) Purposes.--The purposes of the Foundation are-- (1) in conjunction with the Office of the President's Council on Fitness, Sports and Nutrition, to develop a list and description of programs, events and other activities which would further the purposes and functions outlined in Executive Order 13265, as amended, and with respect to which combined private and governmental efforts would be beneficial; (2) to encourage and promote the participation by private organizations in the activities referred to in subsection (b)(1) and to encourage and promote private gifts of money and other property to support those activities; and (3) in consultation with such Office, to undertake and support activities to further the purposes and functions of such Executive Order. (c) Prohibition on Federal Funding.--The Foundation may not accept any Federal funds. SEC. 3. BOARD OF DIRECTORS OF THE FOUNDATION. (a) Establishment and Membership.--The Foundation shall have a governing Board of Directors (hereinafter referred to in this Act as the ``Board''), which shall consist of 9 members each of whom shall be a United States citizen and-- (1) 3 of whom should be knowledgeable or experienced in one or more fields directly connected with physical fitness, sports, nutrition, or the relationship between health status and physical exercise; and (2) 6 of whom should be leaders in the private sector with a strong interest in physical fitness, sports, nutrition, or the relationship between health status and physical exercise. The membership of the Board, to the extent practicable, should represent diverse professional specialties relating to the achievement of physical fitness through regular participation in programs of exercise, sports, and similar activities, or to nutrition. The Assistant Secretary for Health, the Executive Director of the President's Council on Fitness, Sports and Nutrition, the Director for the National Center for Chronic Disease Prevention and Health Promotion, the Director of the National Heart, Lung, and Blood Institute, and the Director for the Centers for Disease Control and Prevention shall be ex officio, nonvoting members of the Board. Appointment to the Board or its staff shall not constitute employment by, or the holding of an office of, the United States for the purposes of laws relating to Federal employment. (b) Appointments.--Within 90 days from the date of enactment of this Act, the members of the Board shall be appointed by the Secretary in accordance with this subsection. In selecting individuals for appointments to the Board, the Secretary should consult with-- (1) the Speaker of the House of Representatives concerning the appointment of one member; (2) the Majority Leader of the House of Representatives concerning the appointment of one member; (3) the Majority Leader of the Senate concerning the appointment of one member; (4) the President Pro Tempore concerning the appointment of one member; (5) the Minority Leader of the House of Representatives concerning the appointment of one member; and (6) the Minority Leader of the Senate concerning the appointment of one member. (c) Terms.--The members of the Board shall serve for a term of 6 years, except that the original members of the Board shall be appointed for staggered terms as determined appropriate by the Secretary. 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The Inspector General of the Department of Health and Human Services and the Comptroller General of the United States shall have access to the financial and other records of the Foundation, upon reasonable notice. (b) Report.--The Foundation shall, not later than 60 days after the end of each fiscal year, transmit to the Secretary and to Congress a report of its proceedings and activities during such year, including a full and complete statement of its receipts, expenditures, and investments. 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National Foundation on Fitness, Sports, and Nutrition Establishment Act - Establishes the National Foundation on Fitness, Sports, and Nutrition as a charitable, nonprofit corporation: (1) to develop, in conjunction with the Office of the President's Council on Fitness, Sports and Nutrition, a list and description of activities which would further the purposes and functions outlined in Executive Order 13265 (established the President's Council on Physical Fitness and Sports) and with respect to which combined private and governmental efforts would be beneficial; (2) to promote private organization participation in, and private gifts to support, those activities; and (3) in consultation with such Office, to undertake and support activities to further the purposes and functions of such Executive Order. Prohibits the Foundation from accepting any federal funds.

_ formcalc _ @xcite is a mathematica package for the calculation of feynman amplitudes . it prepares the amplitudes generated by _ feynarts_@xcite for numerical evaluation . this consists of an algebraic simplification step , including e.g. the tensor reduction and the calculation of fermionic traces , and a code generation step , where the complete fortran code for the evaluation of the squared matrix element is written out . currently , diagrams up to one loop can be simplified , and kinematics are supplied for @xmath0 , @xmath1 , and @xmath2 processes . the present article describes the new features added in version 4 . they can be classified into _ performance features : _ + weyl van der waerden ( wvdw ) formalism , + phase - space integration by the cuba library , + parallelization by shell script , _ convenience features : _ + log - file management , + a simple way to resume aborted calculations , + shell scripts to perform common tasks , _ modularity / reusability features : _ + general - purpose utilities library , + organization into master- and sub - makefiles , + symbol prefixing to avoid name conflicts . furthermore , the new ` feyninstall ` script greatly simplifies the installation or upgrade of the _ feynarts _ , _ formcalc _ , and _ looptools _ packages . amplitudes involving external fermions have the form @xmath3 where the @xmath4 are ( products of ) fermion chains . the textbook recipe is to compute probabilities , such as @xmath5 and evaluate the @xmath6 by standard trace techniques . the problem with this approach is that instead of @xmath7 of the @xmath4 one needs to compute @xmath8 of the @xmath6 . since essentially @xmath9 , this quickly becomes a limiting factor in problems involving many vectors , e.g. in multi - particle final states or polarization effects . the solution is of course to compute the amplitude @xmath10 directly and this is done most conveniently in the wvdw formalism @xcite . the implementation of this technique in an automated program has already been outlined in @xcite and is now tested and available in _ formcalc _ 4 . the ` fermionchains ` option of ` calcfeynamp ` determines how fermion chains are returned : ` weyl ` , the default , selects weyl chains . ` chiral ` and ` va ` select dirac chains in the chiral ( @xmath11 ) and vector / axial - vector ( @xmath12 ) decomposition , respectively . the weyl chains do not need to be further evaluated with ` helicityme ` , which applies the trace technique . the wvdw method has other advantages , too : polarization does not ` cost ' extra in terms of cpu time , that is , one gets the spin physics for free . whereas with the trace technique the formulas become significantly more bloated when polarization is taken into account , in the wvdw formalism one actually needs to sum up the polarized amplitudes to get the unpolarized result . there is also better numerical stability because components of @xmath13 are arranged as ` large ' and ` small ' matrix entries , viz . @xmath14 cancellations of the form @xmath15 for @xmath16 are avoided and hence mass effects are treated more accurately . the recently completed cuba library @xcite has been integrated into _ formcalc _ 4 . it provides four subroutines for multidimensional numerical integration . all four have a very similar invocation and can thus be interchanged easily , e.g. for comparison . the flexibility of a general - purpose method is particularly useful in the setting of automatically generated code . the following algorithms are included : _ vegas _ is the classic monte carlo algorithm which uses importance sampling for variance reduction . it iteratively builds up a piecewise constant weight function , represented on a rectangular grid . each iteration consists of a sampling step followed by a refinement of the grid . the present implementation uses sobol quasi - random numbers for sampling . _ suave _ is a crossover between vegas and miser and combines vegas - style importance sampling with globally adaptive subdivision : until the requested accuracy is reached , the region with the largest error is bisected along the axis in which the fluctuations of the integrand are reduced most . in each half the number of new samples is prorated for the fluctuation . _ divonne _ is a further development of the cernlib routine d151 . it is intrinsically a monte carlo algorithm but has cubature rules built in for comparison , too . the variance - reduction method is stratified sampling . in a first step , a tessellation of the integration region is constructed in which all subregions have an approximately equal value of the spread , defined as @xmath17 minimum and maximum here are sought using methods from numerical optimization . the subregions are then sampled independently with a number of points extrapolated to reach the required accuracy . for each region , the latterly obtained value is compared to the initial rough estimate and if the two are not compatible within their errors , the region is subdivided or sampled once more . additions with respect to the cernlib version are the final comparison phase and the possibility to point out known extrema , to speed up convergence . _ cuhre _ is a new implementation of dcuhre . it is a deterministic algorithm which employs cubature rules of a polynomial degree . variance reduction is by globally adaptive subdivision : until the requested accuracy is reached , bisect the region with the largest error along the axis with the largest fourth difference . [ fig : eetta ] compares the performance of the four algorithms for a real phase - space integration of the process @xmath18 . above all it is very important to have several independent integration methods to cross - check the results . the number of integrand evaluations for the phase - space integration of @xmath19 at a requested relative accuracy of @xmath20 . ] calculations in models like the mssm , where not all input parameters are yet known , often require extensive scans to cover an interesting part of the parameter space . such a scan can be a real cpu hog , but on the other hand , the calculation can be performed completely independently for each parameter set and is thus an ideal candidate for parallelization . the real question is thus not how to parallelize the calculation , but how to automate the parallelization . in _ formcalc _ , the user may specify parameter loops by defining preprocessor variables , e.g. .... # define loop1 do 1 tb = 2 , 30 .... these definitions are substituted at compile time into a main loop of the form + ` loop1 ` + ` loop2 ` + ` ` @xmath21 + ` ` _ _ calculate cross - section _ _ + ` 1 continue ` + the obstacle to automatic parallelization is that the loops are user - defined and in general nested . a serial number is introduced to unroll the loops : + ` s = 0 ` + ` loop1 ` + ` loop2 ` + ` ` @xmath21 + ` s = s + 1 ` + ` if ( s ` _ _ not in allowed range _ _ ` ) goto 1 ` + ` ` _ _ calculate cross - section _ _ + ` 1 continue ` + the serial number range can be specified on the command line so that it is quite straightforward to distribute patches of serial numbers on different machines . most easily this is done in an interleaved manner , since one then does not need to know to which upper limit the serial number runs , i.e. if there are @xmath22 machines available , send serial numbers 1 , @xmath23 , @xmath24 , etc . on machine 1 , send serial numbers 2 , @xmath25 , @xmath26 , etc . on machine 2 , this procedure is completely automated in _ formcalc _ 4 : the user once creates a ` .submitrc ` file in his home directory and lists there all machines that may be used , one on each line . in the case of multi - processor machines he puts the number of processors after the host name . the executable compiled from _ formcalc _ code , typically called ` run ` , is then simply prefixed with ` submit ` . for instance , instead of .... run uuuu 500,1000 .... the user invokes .... submit run uuuu 500,1000 .... the ` submit ` script uses ` ruptime ` to determine the load of the machines and ` ssh ` to log in . handling of the serial number is invisible to the user . due to the parallelization mechanism , a single output file is no longer sufficient . instead of a single log file , _ formcalc _ 4 creates a log directory , opens one log file for each serial number in this directory , and redirects console output to this file . each log file contains both the ` real ' data and the ` chatter ' ( progress , warning , and error messages ) . this has the advantage that no unit numbers must be passed between subroutines every bit of output is simply written to the console ( unit ` * ` in fortran ) . it also makes it easier to pinpoint errors , since the error message appears right next to the corrupted data . the ` real ' data are marked by an @ in column 1 and there exists a simple shell script , ` data ` , to extract the real data from the log file . the new log - file management also provides an easy way to resume an aborted calculation . this works as follows : when running through the loops of a parameter scan , the log file for a particular serial number + may not exist : + then it is created with execute permissions , + may exist , but have execute permissions : + then it is overwritten , + may exist and have read - write permissions : + then this serial number is skipped . + the execute permissions , which serve here merely as a flag to indicate an ongoing calculation , are reduced to ordinary read - write permissions when the log file is closed . in other words , the program skips over the parts of the calculation that are already finished , so all the user has to do to resume an aborted calculation is start the program again with the same parameters . _ formcalc _ 4 includes a few useful shell scripts : ` sfx ` packs all source files ( but not object , executable , or log files ) in the directory it is invoked in into a mail - safe self - extracting archive . for example , if ` sfx ` is invoked in the directory ` myprocess ` , it produces ` myprocess.sfx ` . this file can e.g. be mailed to a collaborator , who needs to say `` ` myprocess.sfx x ` '' to unpack the contents . ` pnuglot ` produces a high - quality plot in encapsulated postscript format from a data file in just one line . in fact , ` pnuglot ` does not even make the plot itself , it writes out a shell script to do that , thus `` ` pnuglot mydata ` '' creates ` mydata.gpl ` which then runs gnuplot , latex , and dvips to create ` mydata.eps ` . the advantage of this indirect method is that the default gnuplot commands in ` mydata.gpl ` can subsequently be edited to suit the user s taste . adding a label or choosing a different line width is , for example , a pretty trivial matter . needless to say , all labels are in latex and type 1 fonts are selected to make the eps file nicely scalable . ` turnoff ` switches off ( and on ) the evaluation of certain parts of the amplitude , which is a handy thing for testing . for example , `` ` turnoff box ` '' switches off all parts of the amplitude with ` box ' in their name . invoking ` turnoff ` without any argument restores all modules . the fortran code is organized in _ formcalc _ 4 into a main code directory , which contains the main program and all its prerequisite files , and subsidiary ` folders ' ( subdirectories to the main code directory ) . the default setup looks like this : ( 200,100 ) ( 55,90)[b]main code directory ( 55,80)[b](created by ` setupcodedir ` ) ( 0,77)(110,77 ) ( 55,77)(55,62 ) ( 55,62)(65,62 ) ( 70,62)[l]`squaredme/ ` ( 70,52)[l](generated by ` writesquaredme ` ) ( 45,77)(45,39 ) ( 45,39)(65,39 ) ( 70,39)[l]`renconst/ ` ( 70,29)[l](generated by ` writerenconst ` ) ( 35,77)(35,16 ) ( 35,16)(65,16 ) ( 70,16)[l]`util/ ` ( 70,6)[l](comes with _ formcalc _ ) each folder is equipped with its own makefile which makes a library of the same name , e.g. the makefile in ` util/ ` makes the library ` util.a ` . these sub - makefiles are orchestrated by the master makefile . libraries required for the main program are listed in the ` libs ` variable and built automatically by invoking the sub - makefiles : .... libs = squared_me.a renconst.a util.a .... the master makefile is no longer overwritten in the code - generation process and is treated like the other driver programs , i.e. a customized copy can be saved in the local drivers directory . occasionally it is useful to have more than one instance of ` squaredme ` ( or ` renconst ` ) , e.g. when computing an hadronic cross - section to which several partonic processes contribute . both ` writesquaredme ` and ` writerenconst ` have the ` folder ` option , with which a unique folder name can be chosen , and the ` symbolprefix ` option , with which the symbols visible to the linker can be prefixed with a unique identifier . this identifier is inserted only at compile time and can easily be changed in the sub - makefile at any time . the ` util ` library is a collection of ancillary routines which currently includes : + system utilities ( log file management ) , + kinematic functions ( pair , eps , @xmath27 ) , + diagonalization routines ( eigenvalues , @xmath27 ) , + univariate integrators ( gauss , patterson ) , + multivariate integrators ( cuba library ) . + older versions of _ formcalc _ used to include these directly into the main program . the library version has the advantage that the linker selects only the routines that are actually needed , and furthermore it is straightforward to add new code . the ` util.a ` library is compiled once when _ formcalc _ is installed and then copied to the main code directory , thus avoiding unnecessary compiles . _ formcalc _ 4 is the latest release of the mathematica package _ formcalc _ for computing feynman diagrams . it has many new features enhancing in particular performance , convenience , and modularity .

_ formcalc _ is a mathematica package for the automatic computation of tree - level and one - loop feynman amplitudes . it accepts diagrams generated by _ feynarts _ , simplifies them , and generates a complete fortran code for their numerical evaluation . version 4 includes new features which enhance performance , convenience of use , and modularity / code reusability .

this article describes 2 patients with neuromuscular disorders on immunotherapy with long - term mmf who developed te . a 77-year - old man with well - controlled myasthenia gravis ( positive acetylcholine receptor binding and modulating antibodies ) on pyridostigmine , prednisone 20 mg qod , and mmf 1,500 mg / day for 3 years presented with a 1-month history of progressive weakness of his right arm and leg , speech difficulty , gait difficulty , and cognitive impairment . examination was notable for expressive aphasia , right - sided hemiparesis , and right - sided hyperreflexia . csf analysis showed elevated protein at 64 mg / dl ( normal 1545 mg / dl ) , 1 white blood cell ( wbc)/mm , and normal glucose . mmf was discontinued and he was treated with pyrimethamine 50 mg daily , sulfadiazine 1,000 mg 4 times per day , and leucovorin 25 mg daily for 2 months without significant improvement . ( a , b ) contrast - enhanced mri demonstrated a 2.3 by 1.3 cm ring - enhancing lesion in the deep white matter of the left frontoparietal lobe . ( c , d ) repeat imaging 1 month later after receiving antitoxoplasmosis treatment . a and c are mri brain fluid - attenuated inversion recovery sequences . ( a ) contrast - enhanced mri demonstrated a second ring - enhancing lesion in the medial right temporal lobe . ( b ) repeat imaging 1 month after receiving antitoxoplasmosis treatment . a 72-year - old woman with a history of inflammatory myopathy presented with fever , confusion , and generalized weakness . diagnosis of inflammatory myopathy had been made 3 years prior after emg and muscle biopsy . she had been treated with mmf 1,500 mg twice a day and prednisone 10 mg once a day for 2.5 years . she had received 2 doses of rituximab 1,000 mg 2 weeks apart 8 months prior to presentation . brain mri demonstrated multiple ring - enhancing lesions with surrounding vasogenic edema ( figure 3 ) . csf analysis showed mild lymphocytic pleocytosis ( 10 wbc / mm , lymphocytes 97% ) and elevated protein at 124 mg / dl . te was confirmed by positivity on csf t gondii b1 gene real - time pcr . serum t gondii igg antibody was positive and serum t gondii igm antibody was negative . the following csf viral pcr studies were negative : epstein - barr virus , human herpesvirus 6 , varicella - zoster virus , cytomegalovirus , herpes simplex virus 1 , and herpes simplex virus 2 . absolute cd3 and cd4 lymphocyte counts were normal at 1,454 and 1,110 cells/l , respectively ( normal 9153,400 cells/l and 5102,320 cells/l , respectively ) . absolute cd19 lymphocyte count was low at 16 cells/l ( normal 105920 cells/l ) , cd19 lymphocyte population was low at 1% , and cd20 was less than 1% of all lymphocytes . serum igg was high at 2,393 mg / dl ( normal 6001,700 mg / dl ) . mmf was discontinued and she was treated with pyrimethamine 50 mg daily , sulfadiazine 1,000 mg 4 times per day , and leucovorin 25 mg daily for 2 months without significant improvement . ( a ) mri brain fluid - attenuated inversion recovery demonstrated multiple lesions with perilesional edema . ( b ) contrast - enhanced mri brain demonstrated multiple foci of ring - enhancing lesions in the bilateral subcortical regions . a 77-year - old man with well - controlled myasthenia gravis ( positive acetylcholine receptor binding and modulating antibodies ) on pyridostigmine , prednisone 20 mg qod , and mmf 1,500 mg / day for 3 years presented with a 1-month history of progressive weakness of his right arm and leg , speech difficulty , gait difficulty , and cognitive impairment . examination was notable for expressive aphasia , right - sided hemiparesis , and right - sided hyperreflexia . csf analysis showed elevated protein at 64 mg / dl ( normal 1545 mg / dl ) , 1 white blood cell ( wbc)/mm , and normal glucose . mmf was discontinued and he was treated with pyrimethamine 50 mg daily , sulfadiazine 1,000 mg 4 times per day , and leucovorin 25 mg daily for 2 months without significant improvement . ( a , b ) contrast - enhanced mri demonstrated a 2.3 by 1.3 cm ring - enhancing lesion in the deep white matter of the left frontoparietal lobe . ( c , d ) repeat imaging 1 month later after receiving antitoxoplasmosis treatment . a and c are mri brain fluid - attenuated inversion recovery sequences . ( a ) contrast - enhanced mri demonstrated a second ring - enhancing lesion in the medial right temporal lobe . a 72-year - old woman with a history of inflammatory myopathy presented with fever , confusion , and generalized weakness . diagnosis of inflammatory myopathy had been made 3 years prior after emg and muscle biopsy . she had been treated with mmf 1,500 mg twice a day and prednisone 10 mg once a day for 2.5 years . she had received 2 doses of rituximab 1,000 mg 2 weeks apart 8 months prior to presentation . brain mri demonstrated multiple ring - enhancing lesions with surrounding vasogenic edema ( figure 3 ) . csf analysis showed mild lymphocytic pleocytosis ( 10 wbc / mm , lymphocytes 97% ) and elevated protein at 124 mg / dl . te was confirmed by positivity on csf t gondii b1 gene real - time pcr . serum t gondii igg antibody was positive and serum t gondii igm antibody was negative . the following csf viral pcr studies were negative : epstein - barr virus , human herpesvirus 6 , varicella - zoster virus , cytomegalovirus , herpes simplex virus 1 , and herpes simplex virus 2 . absolute cd3 and cd4 lymphocyte counts were normal at 1,454 and 1,110 cells/l , respectively ( normal 9153,400 cells/l and 5102,320 cells/l , respectively ) . absolute cd19 lymphocyte count was low at 16 cells/l ( normal 105920 cells/l ) , cd19 lymphocyte population was low at 1% , and cd20 was less than 1% of all lymphocytes . serum igg was high at 2,393 mg / dl ( normal 6001,700 mg / dl ) . mmf was discontinued and she was treated with pyrimethamine 50 mg daily , sulfadiazine 1,000 mg 4 times per day , and leucovorin 25 mg daily for 2 months without significant improvement . ( a ) mri brain fluid - attenuated inversion recovery demonstrated multiple lesions with perilesional edema . ( b ) contrast - enhanced mri brain demonstrated multiple foci of ring - enhancing lesions in the bilateral subcortical regions . mmf is a prodrug of mycophenolic acid ( mpa ) that exerts its immunosuppressive effect by inhibiting purine biosynthesis . specifically , mpa suppresses dna synthesis via a selective , noncompetitive , reversible inhibition of primarily the type ii isoform of inosine monophosphate dehydrogenase , an enzyme central to the de novo production of guanosine . this cytostatic effect is relatively specific to lymphocytes , which are more dependent on this pathway than other cell types . mmf is used in the treatment of several neuroimmunologic diseases , including myasthenia gravis , multiple sclerosis ( ms ) , neuromyelitis optica , chronic inflammatory demyelinating polyneuropathy , multifocal motor neuropathy , and inflammatory myopathy . in most studies we did not find any prior cases of te occurring during the treatment of autoimmune neurologic illnesses or rheumatologic illnesses with mmf . in transplant patients , te has been described in association with different combinations of immunosuppressives used for rejection prophylaxis . for example , te has been reported in regimens containing cyclosporine , azathioprine , tacrolimus , and methylprednisolone . toxoplasmosis infections have recently been reported in association with newer biologic immunotherapies in the treatment of autoimmune disease . infliximab- and adalimumab - associated te have been reported in the treatment of rheumatoid arthritis . natalizumab - associated toxoplasmic chorioretinitis has been described in the treatment of relapsing - remitting ms . in the general us population , the overall seroprevalence of toxoplasma is 22.5% . in regions where toxoplasma is particularly endemic , such as within brazil immunocompetent patients in the general population with latent toxoplasmosis generally have an asymptomatic natural history . severe toxoplasmosis infection occurs when chronic t gondii infection is reactivated in the immunocompromised individual . focal findings may include focal seizures , ataxia , hemisensory loss , hemiparesis , and hemiplegia . definitive diagnosis of te requires a consistent clinical presentation , identification of > 1 consistent lesion on mri or other brain imaging , and detection of the organism by brain biopsy . pcr has been recommended for diagnosis in immunosuppressed individuals , and it has a high specificity of 96%100% . at present , most clinicians begin treatment for te following presumptive clinical diagnosis and rely on empiric diagnosis supported by clinical and radiographic improvement in response to antitoxoplasmosis treatment . brain biopsy is recommended when patients do not respond to toxoplasmosis therapy . the treatment of choice is a combination of pyrimethamine , sulfadiazine , and leucovorin . despite treatment , mortality in patients receiving immunosuppression remains high , with reported mortality rates ranging from 40% to 60% , which is higher than the mortality rate for the aids population ( 13%31% ) . the seroprevalence for toxoplasma in the us region where our cases occurred is relatively low , around 20% . in our 2 cases , both patients were treated with mmf for more than 2 years prior to onset of neurologic symptoms and diagnosis of te . each individual received another immunosuppressive agent in addition to mmf , which may have contributed to the risk of toxoplasmosis infection . in the first case , the patient received low - dose corticosteroids ( 20 mg every other day ) , but there is little evidence to suggest that treatment with low - dose corticosteroids is associated with a significant risk of infection . he did have low cd4 and cd8 t - cell counts consistent with immunosuppression secondary to mmf . in the second case , the patient received rituximab 8 months prior to the development of neurologic symptoms . we could only find one case report of te occurring in an individual who had received long - term rituximab . studies in the transplant and rheumatology patients have suggested an increased incidence of infectious events with higher mmf dosing . the increased risk of infection should be considered in individuals on high - dose mmf ( 3 g / day ) . despite appropriate treatment , both patients had no significant improvement , which reflects the high morbidity and mortality of te . as earlier recognition and treatment has been reported to improve outcomes in te , these case reports emphasize the need to consider te in any patient receiving mmf who presents with new cognitive or neurologic defects . the use of trimethoprim / sulfamethoxazole ( tmp - smx ) prophylaxis to prevent life - threatening opportunistic infections in individuals receiving immunosuppression for treatment of autoimmune disease has previously been recommended for higher - risk individuals . if an mmf dose of 3 g / day is required , then prophylaxis with tmp - smx can be considered . the utility of screening for and prophylaxis against toxoplasmosis in individuals with neuroimmunologic disorders and other autoimmune disorders who receive immunosuppressive therapy requires future study . danilo r. bernardo , jr . contributed to the design , drafting , and revising of the manuscript .

objective : to show that immunotherapy with medications such mycophenolate mofetil ( mmf ) can cause serious complications in patients with neuromuscular disorders.methods:two patients with neuromuscular disorders on immunotherapy with long - term mmf who developed toxoplasmic encephalitis ( te ) were included in this case series.results:one patient with myasthenia gravis and one patient with inflammatory myopathy on immunotherapy with long - term mmf developed severe te . diagnosis was based on clinical presentation , mri brain imaging characteristics , and csf pcr positivity for toxoplasma gondii . both patients were treated with pyrimethamine , sulfadiazine , and leucovorin for 2 months without clinical improvement , and both died.conclusions:immunotherapy with medications such as mmf can cause devastating te in non - hiv patients with neuromuscular disorders . early consideration and recognition of this complication is important to possibly prevent unfavorable outcomes . the utility of screening and prophylaxis against toxoplasmosis in individuals with neuroimmunologic disorders and other autoimmune disorders who receive immunosuppressive therapy requires future study .

dinoflagellate algae are a eukaryotic protist and are the most important primary producer in aquatic environments . some species ( e.g. , alexandrium tamarense , amphidinium carterae , akashiwo sanguinea , cochlodinium polykrikoides , gymnodinium , and karlodinium micrum ) are responsible for harmful algal blooms ( habs ) , affecting fisheries and creating associated economic loss in aquaculture industries . the ichthyotoxic cochlodinium polykrikoides is one of the most common dinoflagellates that cause habs , and it has expanded oceanic regions worldwide [ 2 , 3 ] . thus , its bloom can cause severe environmental impacts and huge economic losses , due to lots of fish mortalities in aquaculture [ 46 ] . in the last three decades , the causative organism has been extensively studied in terms of environmental survey , bloom - forming mechanisms , and/or mitigation measures [ 711 ] ; nevertheless , some issues , like toxic mechanisms and cellular gene response , still remained unclear . molecular study is very useful and crucial for understanding regulation mechanism and molecular characteristics of the causative organism . however , molecular studies of c. polykrikoides especially in terms of toxicogenomics and gene regulation are limited so far . heat shock proteins ( hsps ) are remarkably evolutionary conserved molecular chaperones and are present in all the prokaryotic and eukaryotic organisms . they are distributed into small hsp , hsp60 , hsp70 , hsp90 , and hsp100 , depending on their molecular weight and sequence similarity . hsps have multiple roles , including membrane translocation , protein degradation , protein folding , and repair misfolded proteins , in regulation of protein homeostasis in normal and stressed cells for regulating protein homeostasis in normal and stressed cells [ 12 , 13 ] . hence , hsps are one of the major genes that can be induced and respond to various stressors , and , of them , hsp70 may be firstly induced under stress conditions rather than other hsps . moreover , hsp70 and hsp90 are the most conserved and abundant hsps and are widely involved in the environmental stressors , such as thermal shock , heavy metal , oxidative damage , hypoxia , and xenobiotic chemicals [ 12 , 1416 ] . for this reason , either hsp90 or hsp70 is considered as biomarker for environmental monitoring [ 17 , 18 ] . furthermore , hsp90 and hsp70 may interact with each other , as well as cooperate with other hsps or chaperone to regulate multisignal transduction pathway [ 1921 ] . in cases of the dinoflagellates , several of hsp90 and hsp70 genes have been identified , but majority of researches have focused on phylogenetic relationships or spliced leader sequence analyses in dinoflagellates [ 2225 ] . only few studies have investigated the responses of hsp90 and/or hsp70 under environmental stress conditions [ 2628 ] . for example , we reported hsp70/90 from the dinoflagellates prorocentrum minimum , suggesting that both genes play diverse roles in physiological responses of the dinoflagellate [ 27 , 28 ] . so , it is necessary to discover more molecular information for understanding gene regulation mechanisms in adaptive , survival strategies of dinoflagellates , as well as gene and genomic structures . in the present study , we determined full length sequences of hsp90 and hsp70 of the dinoflagellate c. polykrikoides and characterized their gene and genomic features . these included analysis of genomic dna , deduced protein sequences , phylogenetic relationships , and their gene regulation under metal and nonmetal stress conditions as well . c. polykrikoides was obtained from the national fisheries research and development institute ( nfrdi ) , korea . the c. polykrikoides cells were cultured in f/2 medium at 20c in 12:12 h light - dark cycle , with a photon flux density of about 65 mol photons m s. c. polykrikoides cultures were harvested by centrifugation at 1,000 g for 10 min , frozen immediately in liquid nitrogen and stored at 80c until rna extraction . preserved cells were physically broken by freeze - thawing in liquid nitrogen and further homogenized by a mini - beadbeater ( biospec products inc . , total rna was isolated using the trizol ( invitrogen , carlsbad , ca ) and purified by mini spin columns of rneasy mini kit ( qiagen , valencia , ca ) . for the first strand cdna , 2 different cdna synthesis kits were employed : one was superscript iii first - strand synthesis system ( invitrogen , carlsbad , ca ) for the gene cloning of cphsp70 and cphsp90 ; the other was a maxime rt premix kit with random primers ( intron , seongnam , republic of korea ) for gene expression study . then , the 1st strand cdna templates were diluted 1 : 10 with nuclease - free water for use in subsequent analyses . full length of cphsp70 and cphsp90 sequences was determined by rapid amplification of cdna ends ( race ) . partial gene sequences of cphsp70 and cphsp90 were taken from c. polykrikoides est database ( genbank accession number srr1917383 ) determined by 454 pyrosequencing ( gs - flx titanium ; 454 life sciences , roche , branford , ct ) . cphsp70 and cphsp90 est sequences were used for primer design for full length amplification ( table 1 ) . the 3- and 5-untranslated regions ( utr ) of these genes were determined by using the 3- and 5-race , respectively . for the race , nest pcrs were employed , and the primers used in each pcr were listed in table 1 . reaction conditions for the primary and secondary pcrs were as follows : predenaturation at 96c for 10 min ; 35 cycles of 95c for 30 s , 52c/54c for 30 s , 72c for 100 s , and extension at 72c for 10 min , respectively . positive core pcr products were purified , cloned into pmd20-t vector ( takara , shiga , japan ) , transformed into e. coli competent cells , and subjected to sequencing . the full length of the cphsp70 and cphsp90 was validated by pcr with specific primers ( table 1 ) . the primers used in the cphsp70 and cphsp90 genomic sequence determination were designed according to cdna sequence ( table 1 ) . protein motifs and conserved domains of cphsp70 and cphsp90 protein were analyzed with the online servers and public database , including the prosite ( http://prosite.expasy.org/ ) , compute pi / mw tool ( http://web.expasy.org/compute_pi/ ) , and ncbi conserved domain database ( http://www.ncbi.nlm.nih.gov/structure/cdd/wrpsb.cgi ) . bootstrap consensus tree inferred from 1,000 replicates was taken to represent the evolutionary history of the taxa analyzed . the tree is drawn to scale , with branch lengths in the same units as those of the evolutionary distances used to infer the phylogenetic tree . the evolutionary distances were computed using the jtt matrix - based method and were in the units of the number of amino acid substitutions per site . in the sequences analysis , it involved 28 amino acid sequences and had a total of 489 positions in the final hsp90s dataset . in the case of hsp70s , it involved 23 amino acid sequences . there were a total of 586 positions in the final hsp70s dataset . number 425044 , sigma , mo ) , and aroclor 1016 ( 48701 , sigma , a type of pcbs ) were employed in the present study . to test the doses effect of toxicants on cphsp70 and cphsp90 transcriptional expression , a series of concentrations of each toxicant were added in the c. polykrikoides cultures ( with final concentration of cuso4 : 1 , 5 , and 8 mg l ) . the treated and untreated cultures were harvested for gene expression analysis at indicated time points . rna extraction and cdna were prepared with the same manner described previously . gene expression and statistical analysis cphsp90 ( genbank number kp010829 ) was 2,316 bp in length , coding 709 amino acids ( aa ) with theoretical isoelectric point ( pi ) 4.9 and molecular weight ( mw ) 81.7 kda . its deduced protein shared the highest sequence similarity ( 681 identities in 709 amino acids ) with those of the dinoflagellate prorocentrum minimum ( hsp90 , genbank number afd34191 ) , followed by karlodinium veneficum with 665 identities in 709 aa ( hsp90 ; abi14419 ) . generally , the hsp90 contains five conserved motifs defined as hsp90 signature motif ; these five signature motifs nkeiflrelisnasdaldkiry , lgtiaksgt , igqfgvgfysaylv , iklyvrrvfi , and vvdsedlplnisre were identified by comparison with other hsp90s ( figure 1(a ) ) . furthermore , the conserved meevd was identified in the c - terminus of deduced cphsp90 , which indicated that cphsp90 protein belongs to the cytosolic hsp90 family . phylogenetic analysis was performed using cphsp90 protein and other dinoflagellate hsp90 proteins ( figure 1(b ) ) . a resultant tree showed c. polykrikoides with gymnodinium fuscum and lepidodinium chlorophorum was clustered into one clade , of which taxon position belonged to the order gymnodiniales . in addition , full orf of cphsp70 ( genbank number kp010828 ) was 1,944 bp in length , coding 648 aa with theoretical pi 5.12 and mw 70.8 kda . cphsp70 aa showed 94% maximum identity with those of the dinoflagellates crypthecodinium cohnii ( genbank number aam02973 ) and prorocentrum minimum ( abi14407 ) , followed by 88% identity with perkinsus marinus ( xp_002780413 ) . we identified three hsp70 motifs , idlgttys , iydmgggtfdvsll , and vvlvggstripkvqs , in this protein ( figure 2(a ) ) . in addition , the eevd motif was identified in the cphsp70 protein c - terminus , which indicated that the cphsp70 located in the cytoplasm of the cell . a neighbor - joining tree was constructed using dinoflagellates hsp70 and other eukaryotic hsp70s ( figure 2(b ) ) . as expected , all the dinoflagellate hsp70s were clustered into one clade , which showed closest relationship with perkinsea , followed by apicomplexa . all the analyzed dinoflagellates , perkinsea , and apicomplexa were grouped into one clade belonging to alveolata . genomic regions of each cphsp70 and cphsp90 were amplified by pcr . as a result , we found that no intron was presented in the cphsp70 ( kp010830 ) coding genome . in addition , the gene was encoded in tandem arrangement manner with the separation of intergenic spacers ( figures 3(a ) and 3(b ) ) , which was 397 bp in length , and was found in cphsp70 genome sequence . on the other hand , interestingly , we found one intron as in cphsp90 coding genome ( kp010831 ) ( figure 3(c ) ) , which was 454 bp in length , but no intergenic region was found , as judged by pcr . this structure was different from that of a. carterae hsp90 genomic sequence ( 25 introns ) , and a. carterae hsp90 gene was encoded in tandem arrangement . although a. carterae hsp90 and cphsp90 proteins showed highly homologous phylogenic relationships , their genomic dna represented quite different characteristics . algicide chemical treatments are one of the powerful tools to remove habs , and the physiological effects of individual algicides on the habs have been widely investigated . for example , the algicides oxidizing naocl and nonoxidizing cuso4 can cause considerable decreases of c. polykrikoides cell numbers and pigment contents and also affect their chlorophyll autofluorescence . nevertheless , there is no report about the cuso4 and naocl effect on the c. polykrikoides at molecular level , especially in terms of gene transcription . in general , effects of the cuso4 on aquatic organisms are relative to the formation of reactive oxygen species ( ros ) and can regulate the photosynthesis related gene expression and increase the antioxidant enzyme activity in the algae [ 39 , 40 ] . in the present study , the transcriptional expression of cphsp90 and cphsp70 showed similar expression pattern after cuso4 treatment ( figure 4 ) . the transcriptional expression level of these two genes was first upregulated and then decreased with increased concentration of cuso4 . the cphsp90 transcription showed similar expression pattern under 1.0 mg l and 5.0 mg l cuso4 treatments with 5.1- and 4.7-fold changes compared to that of control , respectively . these expression patterns were also displayed by cphsp70 , showing 3.7- and 3.1-fold changes under 1.0 mg l and 5.0 mg l cuso4 treatments compared to that of control . l or 5.0 mg l cuso4 treatment ( figures 4(a ) and 4(b ) ) . this result suggested that the cphsp90 and cphsp70 may be involved in cuso4 induced gene regulation in c. polykrikoides . this result was congruent with our previous results , showing that both genes were considerably induced by exposure of cuso4 in the dinoflagellate p. minimum [ 27 , 28 ] . however , we found that the expression patterns of hsp70 genes were different between c. polykrikoides and p. minimum ( pm ) exposed to the same cuso4 . l of cuso4 ) , whereas the pmhsp70 expression was the highest level at 1.0 mg l and then decreased , possibly due to cell deaths . according to these results , we predicted that the hsp90 and hsp70 are commonly involved in metal cuso4 induced gene regulation in the dinoflagellates , but their expression patterns may depend on exposed doses and testing species . oxidizing chlorine is one of biocides that are commonly used in controlling the quality of the water . hypochlorites may have primary deleterious effect on the dna synthesis or progress oxidation of thiol groups and further effect on the cell wall and protein . in the present study , the expression pattern showed response of cphsp90 and cphsp70 depending on the doses of the naocl . interestingly , cphsp90 and cphsp70 were not induced by lower concentration ( 0.02 mg l ) of naocl but significantly upregulated by relatively high concentrations ( 0.1 , 0.3 , and 0.5 mg l ) of naocl ( figures 4(c ) and 4(d ) ) . both cphsp90 and cphsp70 in 0.3 mg l naocl treated cells showed 8.5- and 13.4-fold changes compared to that of control , which were highest expression level among naocl treated cells . the chlorine - based disinfectants induced hsp70 gene expression was also found in the c. parvum oocysts . there are many of chemicals that presented in the aquatic system by industry or agriculture sewerage . they are one of the endocrine disturbing chemicals ( edcs ) and have toxic effect to various organisms . according to our previous work , edcs , including pcb , were very toxic to microalgae , potentially affecting the photosystem ii energy flow , of which results suggested their toxic effect on the dinoflagellates . in this study , we examined the gene expressional response of cphsp70 and cphsp90 in c. polykrikoides exposed to pcb . the transcriptional expressions of cphsp70 and cphsp90 were gradually decreased with increasing pcb concentration ( figure 5 ) , with lowest expression level of 0.42- and 0.23-fold under 0.5 mg l pcb exposure compared to untreated cultures . however , neither pmhsp90 nor pmhsp70 was up- or downregulated by the pcb exposure in the dinoflagellate prorocentrum minimums [ 27 , 28 ] . according to these results , we speculated that the pcb may have a differential effect on the dinoflagellates among species . the aroclor 1016 , which is one of dioxin - like pcbs , was employed . it is clear that the aryl hydrocarbon receptor ( ahr ) mediated pathway is involved in the dioxin - like pcbs adverse effect mechanism [ 45 , 46 ] . a dimer of hsp90 is essential compound that binds to the inactive ahr protein in the cytoplasm and needs to be released from ahr protein complex when ahr is activated [ 4750 ] . according to these findings , we predict that the cphsp90 may bind to ahr and express at a high level in the normal conditions . the cphsp90 may be released , and then the protein may be activated to participate in the signal transduction of the cells , when c. polykrikoides is exposed to pcb . the essential cphsp90 amount was decreased with increasing concentration of pcb in the c. polykrikoides . at present , it was not clear ; thus we needed more experiments to clarify these gene responses in the dinoflagellate , by using additional edcs and testing species in future . in addition to this , the cphsp70 and cphsp90 showed similar expression patterns under the same pcb treatment ( figures 4 and 5 ) . both cphsp90 and cphsp70 proteins contain eevd motif , which is tetratricopeptide repeat domain binding site at the c - terminus , and some proteins can bind with hsp90 and hsp70 to assemble as protein complex to play function such as in the triage of damaged and aberrant proteins for degradation process [ 16 , 52 ] . the gene transcription pattern of cphsp90 and cphsp70 results implied these two genes may have cooperative function in the c. polykrikoides toxicant induced gene regulation [ 16 , 52 ] . in conclusion , this study firstly determined full length cdnas of two hsps ( hsp70/90 ) from the harmful dinoflagellate c. polykrikoides and characterized molecular features such as conserved motifs , coding genomic region , and phylogenetic relatedness to other eukaryotes . cphsp70 had quite similar cdna and genomic coding structures ( e.g. , no intron and tandem arrangement ) to those in the other dinoflagellates ; however , cphsp90 was different from those of other dinoflagellate hsp90s in coding genomic structure ( one intron and no intergenic region ) . in addition , both cphsp90 and cphsp70 may be involved in responding to the cuso4 , naocl , and pcb caused stress .

the marine dinoflagellate cochlodinium polykrikoides is responsible for harmful algal blooms in aquatic environments and has spread into the world 's oceans . as a microeukaryote , it seems to have distinct genomic characteristics , like gene structure and regulation . in the present study , we characterized heat shock protein ( hsp ) 70/90 of c. polykrikoides and evaluated their transcriptional responses to environmental stresses . both hsps contained the conserved motif patterns , showing the highest homology with those of other dinoflagellates . genomic analysis showed that the cphsp70 had no intron but was encoded by tandem arrangement manner with separation of intergenic spacers . however , cphsp90 had one intron in the coding genomic regions , and no intergenic region was found . phylogenetic analyses of separate hsps showed that cphsp70 was closely related with the dinoflagellate crypthecodinium cohnii and cphsp90 with other gymnodiniales in dinoflagellates . gene expression analyses showed that both hsp genes were upregulated by the treatments of separate algicides cuso4 and naocl ; however , they displayed downregulation pattern with pcb treatment . the transcription of cphsp90 and cphsp70 showed similar expression patterns under the same toxicant treatment , suggesting that both genes might have cooperative functions for the toxicant induced gene regulation in the dinoflagellate .

one of the fundamental objects associated to a hyperplane arrangement @xmath3 is the module @xmath4 of logarithmic one - forms with pole along the arrangement or ( dually ) the module @xmath5 of derivations tangent to the arrangement . both are graded @xmath6 modules ; @xmath7 is defined via : @xmath8 for all @xmath9 such that @xmath10 . over a field of characteristic zero , @xmath11 , where @xmath12 is the euler derivation and @xmath13 corresponds to the module of syzygies on the jacobian ideal of the defining polynomial of @xmath14 . when @xmath15 or @xmath16 , an elegant theorem of terao relates the freeness of the module @xmath5 to the poincar polynomial of @xmath17 . in this note , we restrict to @xmath18 , but broaden the class of curves which make up the arrangement . in particular , suppose @xmath19 where each @xmath20 is a smooth rational plane curve ; call such a collection a conic - line ( cl ) arrangement . [ firstex ] for the cl arrangement below , @xmath21 . we begin with some facts about hyperplane arrangements ; for more information see orlik and terao @xcite . a hyperplane arrangement @xmath14 is a finite collection of codimension one linear subspaces of a fixed vector space v. @xmath14 is _ central _ if each hyperplane contains the origin * 0 * of v. the intersection lattice @xmath22 of @xmath14 consists of the intersections of the elements of @xmath14 ; the rank of @xmath23 is simply the codimension of @xmath24 . v is the lattice element @xmath25 ; the rank one elements are the hyperplanes themselves . @xmath14 is called _ essential _ if rank @xmath26 dim @xmath27 . the mbius function @xmath28 : @xmath29 is defined by @xmath30 we now restrict to the case that @xmath27 is complex . a foundational result is that the poincar polynomial of @xmath31 is purely combinatorial ; in particular @xmath32 an arrangement @xmath33 is _ free _ if @xmath34 ; the @xmath35 are called the _ exponents _ of @xmath14 . terao s famous theorem @xcite is that if @xmath34 , then @xmath36 . if @xmath37 is central , then @xmath38 also defines a set of lines in @xmath39 , and obviously @xmath40 , where @xmath41 is the complement of the corresponding arrangement of lines in @xmath18 . hence @xmath42 it follows from terao s theorem that if @xmath43 , then @xmath44 . this can be generalized @xcite to line arrangements which are not free , using the chern polynomial . the motivating question of this paper is : _ what happens if the arrangement of lines is replaced with a cl arrangement ? _ in @xcite , cogolludo - agustn studies the complement of an arrangement of rational curves in @xmath39 , where the individual curves can have singularities , and can meet non - transversally . the main result is that the cohomology ring of the complement to a rational curve arrangement is generated by logarithmic @xmath45 and @xmath46-forms and its structure depends on a finite number of invariants of the curve . one fact is that if @xmath41 is the complement of an arrangement of @xmath47 irreducible curves in @xmath39 , then @xmath48 @xmath49 where @xmath50 is the number of branches passing thru @xmath51 , and @xmath52 is the normalization of @xmath20 . since we are assuming that all the @xmath20 are smooth and rational , we have that @xmath53 where the intersection poset @xmath54 is defined precisely as for a linear arrangement ( typically , @xmath54 is only a poset , not a lattice ) . a crucial distinction between line and curve arrangements , even in our simple setting , is the difference between the milnor and tjurina numbers at a singularity . let @xmath55 be a reduced ( but not necessarily irreducible ) curve in @xmath56 , let @xmath57 , and let @xmath58 denote the ring of convergent power series . the milnor number of @xmath59 at @xmath60 is @xmath61 to define @xmath62 for an arbitrary point @xmath51 , we translate so that @xmath51 is the origin . the tjurina number of @xmath59 at @xmath60 is @xmath63 a singularity is quasihomogeneous iff there exists a holomorphic change of variables so the defining equation becomes weighted homogeneous ; @xmath64 is weighted homogeneous if there exist rational numbers @xmath65 such that @xmath66 is homogeneous . in @xcite , reiffen proved that if @xmath67 is a convergent power series with isolated singularity at the origin , then @xmath67 is in the ideal generated by the partial derivatives if and only if @xmath68 is quasihomogeneous ( see @xcite for a generalization ) . as noted earlier , for a line arrangement with defining polynomial @xmath69 , @xmath70 consists of the syzygies on the jacobian ideal @xmath71 of @xmath69 . if @xmath72 is a reduced curve , then after a change of coordinates , we may assume that @xmath73 has no singularities on the line @xmath74 . dehomogenizing so that @xmath75 yields : @xmath76/\langle \frac{\partial f}{\partial x},\frac{\partial f}{\partial y } , f \rangle = \!\!\!\!\sum\limits_{p \in \text{sing}(c)}\!\!\!\!\tau_p(f).\ ] ] it follows that if all the singular points are quasihomogeneous then @xmath77 for a line arrangement , the singularities are always quasihomogeneous , but this is not the case for cl arrangements : let @xmath78 be as below : @xmath79 has five singular points , all ordinary . when @xmath51 is an ordinary singularity and @xmath59 has @xmath47 distinct branches at @xmath51 , then @xmath80 , so the sum of the milnor numbers is 20 . however , @xmath81 ; at @xmath82 we have @xmath83 but @xmath84 . the first criterion for the freeness of @xmath85 is @xmath33 is free exactly when there exist @xmath86 elements @xmath87 such that the determinant of the matrix @xmath88 $ ] is a nonzero constant multiple of the defining polynomial of @xmath33 . saito s criterion holds for an arrangement of reduced hypersurfaces @xmath89 ; let @xmath90 where @xmath91 , and @xmath92 . by induction , @xmath93 so we have @xmath94 any arrangement of ( reduced ) hypersurfaces will have a singular locus of codimension two . as for a linear arrangement , @xmath95 , with @xmath96 , so freeness is equivalent to @xmath97 ( so also equivalent to @xmath71 cohen - macaulay ) . by the hilbert - burch theorem ( @xcite ) , any codimension two cohen - macaulay ideal @xmath98 with @xmath99 generators is generated by the maximal minors of an @xmath100 matrix @xmath101 , whose columns generate the module of first syzygies on @xmath98 . so when @xmath102 , appending a column vector @xmath103 $ ] to @xmath101 and taking the determinant yields a multiple of @xmath69 , by euler s formula . saito s criterion is most useful when an explicit set of candidates for the generating set of @xmath104 is known . there are two other fundamental tools that can be used to prove that a line arrangement is free . the first method is based on an inductive operation known as deletion - restriction : given an arrangement @xmath14 and a choice of hyperplane @xmath105 , set @xmath106 the collection @xmath107 is called a _ triple _ , and a triple yields ( see proposition 4.45 of @xcite ) a left exact sequence @xmath108 for a triple with @xmath109 , more is true ( see @xcite ) : after pruning the euler derivations and sheafifying , there is an exact sequence @xmath110 where @xmath111 ; @xmath112 in @xcite , terao showed that freeness of a triple is related via : [ thm : teraoad]@xmath113addition - deletion@xmath114 let @xmath107 be a triple . then any two of the following imply the third * @xmath115 * @xmath116 * @xmath117 theorem [ thm : teraoad ] applies in general , not just to arrangements in @xmath39 . a smooth conic is intrinsically a @xmath118 , so it is natural to ask if cl arrangements which admit a short exact sequence similar to ( [ eq : ses ] ) have an addition - deletion theorem ; we tackle this in the next two sections . a second criterion for freeness is special to the case of line arrangements ; to state it we need to define freeness for _ multiarrangements_. a multiarrangement @xmath119 is an arrangement together with a multiplicity @xmath120 for each hyperplane . the module of derivations consists of @xmath121 such that @xmath122 . as shown by ziegler in @xcite , freeness of multiarrangements is not combinatorial ; for recent progress see @xcite . [ thm : yoshi]@xmath113yoshinaga s multiarrangement criterion @xcite@xmath114 @xmath123 is free iff @xmath124 and @xmath125 the multiarrangement @xmath126 has minimal generators in degree @xmath127 and @xmath128 . the main results of this paper ( theorems [ thm : adline ] and [ thm : adconic ] ) show that an addition - deletion construction holds for cl arrangements with quasihomogeneous singularities ; the freeness of example [ firstex ] is explained by our results . as one application , we show that a free cl arrangement , when restricted to different lines , can yield multiarrangements with different exponents ; hence any version of theorem [ thm : yoshi ] for cl arrangements will be quite subtle . an addition - deletion theorem for multiarrangements has recently been proven by abe - terao - wakefield in @xcite ; our results are the first ( to our knowledge ) to give an inductive criterion for freeness for nonlinear arrangements . let @xmath129 be a triple of cl arrangements in @xmath130 , where @xmath131 , @xmath132 and @xmath133 _ is a line_. we begin by examining some examples : let @xmath134 be the union of : @xmath135 @xmath136 is free with exponents @xmath137 , and the degree of the jacobian ideal is @xmath138 , which is equal to the sum of the milnor numbers at the intersection points . therefore at each singular point @xmath139 . if we restrict to any line , the corresponding multiarrangement has two points of multiplicity 3 , and it follows from @xcite that the exponents are @xmath140 . hence the obvious generalization of yoshinaga s criterion does not hold . let @xmath141 and let @xmath142 . the degree of the jacobian ideal is @xmath143 , which is equal to the sum of milnor numbers at the points . it will follow from our results that @xmath144 is free with exponents @xmath145 . let @xmath146 and let @xmath147 . then @xmath148 is free with exponents @xmath149 . the degree of the jacobian ideal is @xmath150 , whereas the sum of the milnor numbers is 38 ; the singularity at @xmath82 has @xmath84 and @xmath83 . for cl arrangements similar to @xmath151 , there is an addition - deletion theorem : a triple @xmath129 of cl arrangements is called quasihomogeneous if @xmath139 at each singular point of @xmath134 and @xmath79 . [ thm : adline ] let @xmath152 be a quasihomogeneous triple with @xmath153 . the following are equivalent : 1 . @xmath134 is free with exponents @xmath154 . @xmath79 is free with exponents @xmath155 . examples 2.1 and 2.2 illustrate the theorem ; before giving the proof of theorem [ thm : adline ] , we need some preliminaries . [ lem : derexact ] let @xmath156 . then the maps @xmath157 , @xmath158 and @xmath159 , @xmath160 are well defined and yield an exact sequence : @xmath161 let @xmath162 be the defining polynomial of @xmath79 , where @xmath163 is the defining polynomial of @xmath134 . then the defining polynomial of @xmath164 is @xmath165 . if @xmath166 , then @xmath167 for some @xmath168 ; @xmath169 so @xmath51 is well defined and injective . let @xmath170 . then @xmath171 , so @xmath172 . if @xmath173 , then @xmath174 and @xmath175 , hence @xmath176 , where @xmath177 . because @xmath178 , @xmath179 . since @xmath24 and @xmath163 are relatively prime , we get that @xmath180 , which implies that @xmath181 . it remains to show is that @xmath182 is well defined . for suitable @xmath183 and @xmath184 we have that @xmath185 let @xmath186 be a line in @xmath134 defined by the vanishing of @xmath187 for some @xmath188 and @xmath189 , and let @xmath170 . then @xmath190 , so evaluating at @xmath191 and using the earlier observation that @xmath172 , we find @xmath192 . now suppose @xmath59 is a conic in @xmath134 ; after a change of coordinates we may assume @xmath59 intersects @xmath156 in the points @xmath82 and @xmath193 . then @xmath194 and @xmath195 , where @xmath196 is some linear form . we have @xmath197 evaluating at @xmath191 and again using that @xmath172 we find @xmath198 since @xmath199 and @xmath200 are relatively prime we obtain @xmath201 this shows that for each factor @xmath202 of @xmath203 , @xmath204 so the map @xmath182 is well defined . it follows that @xmath205(-(k-1))$ ] , where @xmath206 . a similar argument works if @xmath59 is tangent to @xmath207 . [ lem : admilnors ] let @xmath208 and @xmath209 be two reduced plane curves with no common component , meeting at a point @xmath51 . then @xmath210 where @xmath211 is the intersection number of @xmath208 and @xmath209 at @xmath51 . see @xcite , theorem 6.5.1 ; the point is that the milnor fiber is a connected curve , and the result follows from using the additivity of the euler characteristic and the interpretation of @xmath62 as the first betti number of the milnor fiber . [ prop : sesline ] let @xmath129 be a quasihomogeneous triple . then @xmath212 is also right exact . it follows from lemma [ lem : derexact ] that quotienting by the euler derivation and sheafifying yields the left exact sequence above ; so it will suffice to show that @xmath213 , where @xmath214 denotes the hilbert polynomial . for an cl arrangement @xmath79 with @xmath215 lines and @xmath47 conics , let @xmath216 . we have an exact sequence : @xmath217 where @xmath218 $ ] and @xmath219 is the jacobian ideal of the defining polynomial of @xmath79 . since @xmath220 @xmath221 we find that @xmath222 by the assumption that @xmath129 is a quasihomogeneous triple , @xmath223 let @xmath224 be the sum of milnor numbers of points off @xmath207 , so @xmath225 since @xmath226 , by lemma [ lem : admilnors ] , the above is @xmath227 as @xmath228 and @xmath229 , we obtain : @xmath230 by bezout s theorem , @xmath231 so @xmath232 , hence @xmath233 since @xmath234 , this yields the result . a coherent sheaf @xmath235 on @xmath236 is @xmath237regular iff @xmath238 for every @xmath239 . the smallest number @xmath215 such that @xmath235 is @xmath237regular is @xmath240 . [ lem : regbounds ] for a quasihomogeneous triple with @xmath241 , @xmath242 immediate from proposition [ prop : sesline ] ( see @xcite ) . [ lem : lineexact ] if @xmath243 , then there is an exact sequence of @xmath244-modules : @xmath245 for all @xmath246 , @xmath247 , so the long exact sequence in cohomology arising from proposition [ prop : sesline ] and the vanishing of @xmath248 yield an exact sequence : @xmath249 theorem a.4.1 of @xcite relates a graded module to its sheaf and local cohomology ( at the maximal ideal @xmath250 ) modules : @xmath251 this is true also for @xmath252 and @xmath253 . by @xcite , a.4.3 , @xmath254 if @xmath255 . lemma 2.1 of @xcite gives the desired bound on depth for the modules of derivations , which concludes the proof . the next two lemmas prove the two implications @xmath256 and @xmath257 of theorem [ thm : adline ] . in what follows , @xmath129 is a quasihomogeneous triple , with @xmath207 a line and @xmath258 . [ lem : lines1 ] if @xmath134 is free with @xmath259 , then @xmath79 is free with @xmath260 . first , if @xmath261 $ ] , and @xmath262 is a free graded @xmath244-module with generator in degree @xmath188 , then the hilbert series satisfies @xmath263 if @xmath134 is free with exponents @xmath154 , then @xmath264 . it follows from the proof of proposition [ prop : sesline ] that @xmath265 . so by lemma [ lem : lineexact ] and the additivity of hilbert series on an exact sequence , @xmath266 since @xmath267 , @xmath268 . by lemma [ lem : regbounds ] , if @xmath269 , then @xmath270 ; and if @xmath271 , then @xmath272 . if @xmath271 , then a free resolution for @xmath273 is of the form : @xmath274 from regularity constraints , @xmath128 must be at most @xmath275 . as this is a minimal free resolution , and it is impossible to have a syzygy on a single generator , the only situation which can actually arise occurs when @xmath276 : @xmath277 let @xmath278 be two independent derivations in @xmath273 of degrees @xmath279 and @xmath280 ; our computation of the hilbert series , combined with the fact that @xmath281 means such derivations must exist . let @xmath282 be a basis for @xmath283 with @xmath284 and @xmath285 , and @xmath12 the euler derivation . now note that @xmath286 , for otherwise in @xmath273 there would be an element of degree @xmath127 . so @xmath287 . since @xmath288 , then @xmath289 and @xmath290 , where @xmath291 is a constant , @xmath292 , @xmath293 and @xmath294 . for a resolution as above , @xmath295 , where @xmath207 is a linear form and @xmath296 . hence @xmath297 and since @xmath282 is a basis we find that @xmath291 vanishes and @xmath298 . but @xmath299 and @xmath287 . since @xmath300 , @xmath24 must divide @xmath68 , and so @xmath301 for some @xmath302 . since @xmath295 , we obtain @xmath303 , a contradiction . if @xmath304 , simply switch the roles of @xmath127 and @xmath275 above . [ lem : lines2 ] if @xmath79 is free with @xmath260 , then @xmath134 is free with @xmath259 . in order to obtain an appropriate vanishing , we need to dualize . apply @xmath305 to the exact sequence @xmath306 the vanishing of @xmath307 and @xmath308 yield an exact sequence : @xmath309 the free @xmath310 resolution for @xmath311 is : @xmath312 so @xmath313 . since @xmath314 , combining this with the long exact sequence in cohomology yields a regularity bound @xmath315 and the exact sequence of @xmath316modules : @xmath317 with @xmath318 . so : @xmath319 an argument as in the proof of lemma [ lem : lines1 ] shows that @xmath320 , hence @xmath136 is free with exponents @xmath154 . a free cl arrangement , when restricted to a line , can yield different multiarrangements . in example 2.2 , add the line @xmath321 , where @xmath322 . then @xmath207 passes through @xmath323 , and the choices for @xmath224 ensure that @xmath207 is not tangent to any conic , and misses all singularities save @xmath323 . the new arrangement is quasihomogeneous , and @xmath207 meets @xmath324 in six points . by theorem [ thm : adline ] , the new arrangement is free with exponents @xmath325 . restrict this new arrangement to the line @xmath326 . after a change of coordinates , we obtain a multiarrangement with defining polynomial @xmath327 this is exactly ziegler s example from @xcite : @xmath328 gives exponents @xmath329 , and for @xmath330 , the exponents are @xmath331 . let @xmath129 be a triple of cl arrangements in @xmath130 , where @xmath59 is a conic in @xmath79 , and @xmath332 , @xmath333 . we begin with some examples . suppose @xmath79 is as in example 2.2 , so @xmath79 has quasihomogeneous singularities , and is free with exponents @xmath145 . if we delete one of the conics , the resulting arrangement @xmath334 is free and quasihomogeneous , with exponents @xmath335 . when @xmath275 is odd , the situation is more complicated : let @xmath134 be the braid arrangement @xmath336 , and @xmath337 , where the conic @xmath338 . @xmath134 is a free arrangement with exponents @xmath335 , and @xmath339 . @xmath2 is also quasihomogeneous , but not free . let @xmath79 be the quasihomogeneous cl arrangement with defining polynomial @xmath340 . @xmath341 is free with exponents @xmath342 . deleting the conic yields a free line arrangement with exponents @xmath343 . [ thm : adconic ] let @xmath129 be a quasihomogeneous triple , with @xmath344 . if @xmath345 then the following are equivalent : 1 . @xmath134 is free with @xmath346 . @xmath79 is free with @xmath347 . if @xmath348 then : 1 . @xmath349 . if @xmath350 with @xmath351 then @xmath79 is not free . 3 . if @xmath352 with @xmath351 then @xmath134 is not free . we begin with some preliminaries . after an appropriate change of coordinates , we may suppose that @xmath353 . let @xmath188 be the composition of the maps @xmath354 where @xmath355 , and let @xmath356 be the composite map : @xmath357 \stackrel{\phi}{\longrightarrow}\mathbb k[s^2,st , t^2 ] \hookrightarrow \mathbb k[s , t],\ ] ] where @xmath358 .1 in let @xmath359 be a derivation . then @xmath360 , which means @xmath361 for some @xmath168 . via the map @xmath356 this translates into @xmath362 so there exist @xmath363 $ ] such that @xmath364 .1 in if @xmath365 is a ring map and @xmath101 is an @xmath366module , let @xmath367 denote the @xmath316module obtained by restriction of scalars . there is an exact sequence of @xmath316modules @xmath368 where @xmath369 for every @xmath370 and @xmath371 are defined as above ; and @xmath372 is the arrangement of the reduced points @xmath373 in @xmath374 . it is easy to check that @xmath375 is a homomorphism . for exactness , note : @xmath376 it remains to show that the image of @xmath375 is in @xmath377 . suppose @xmath378 is a line of @xmath79 . let @xmath379 . then @xmath380 for some @xmath381 . therefore @xmath382 which implies @xmath383 this means that @xmath384 $ ] . since @xmath385 is the defining polynomial of the two points @xmath386 in @xmath374 , we get that @xmath387 is a derivation on the arrangement of these two points . .1 in suppose @xmath388 is a conic in the cl arrangement @xmath79 . let @xmath359 . computations as above show that @xmath389 @xmath390.\ ] ] since @xmath391 is the defining polynomial of the four points @xmath392 in @xmath374 , we get that @xmath387 is a derivation on the arrangement of these four points . similar arguments work in the case of tangencies . let @xmath393 such that @xmath394 . then @xmath395 with @xmath396 . thus @xmath397 and @xmath121 is the euler derivation in @xmath341 . so quotienting by the euler derivations yields an exact sequence : @xmath398 since @xmath399 , after sheafifying , @xmath400 , and hence the sheafification of @xmath401 is @xmath402 . [ lem : hpconic ] @xmath403 . case 1 : @xmath345 . let @xmath12 be the divisor of the reduced @xmath275 points @xmath404 . then the ideal sheaf @xmath405 , where @xmath406 $ ] of degree @xmath345 . there exists @xmath407 , unique modulo @xmath408 , such that @xmath409 . clearly @xmath410 can not divide @xmath411 , otherwise @xmath412 , so the ideal of the reduced @xmath275 points on @xmath59 is @xmath413 . hence @xmath414 as an ideal of @xmath415 . as an @xmath316module , it has free resolution @xmath416 which yields : @xmath417 .1 in case 2 : @xmath348 . let @xmath12 be the divisor of the reduced @xmath275 points @xmath404 . then the ideal sheaf @xmath405 , where @xmath418 $ ] of degree @xmath348 . let @xmath419_1 $ ] be two independent linear forms which do not divide @xmath68 , and let @xmath420 . since @xmath421 , then @xmath422 defines the same ideal sheaf on @xmath374 as @xmath423 . so @xmath424 . both @xmath425 and @xmath426 are of even degree @xmath427 . so there exist @xmath428 $ ] of degree @xmath99 such that @xmath429 . next we show that @xmath430 is the ideal of the reduced points @xmath431 on @xmath59 . to see this , note that if @xmath432 , then @xmath433 . so @xmath434 , and hence @xmath435 . clearly @xmath410 does not divide @xmath436 , otherwise @xmath437 is identically zero . also , suppose @xmath438 , where @xmath439 is a constant . then @xmath440 , i.e. @xmath441 ; a contradiction . so @xmath219 is the ideal of @xmath442 points on the conic @xmath443 . by the hilbert - burch theorem , such an ideal is minimally generated by the @xmath444 minors of @xmath445 $ ] where both @xmath224 and @xmath446 have degree @xmath215 . so indeed @xmath447 , and @xmath448 . as an @xmath316module it has free resolution @xmath449 } } { \longrightarrow } s^2(-1-m)\longrightarrow \langle \bar{g_1},\bar{g_2 } \rangle \longrightarrow 0,\ ] ] so for the odd case we find that @xmath450 @xmath451 [ prop : sheafconicexact ] for a quasihomogeneous triple @xmath452 , the sequence @xmath453 is exact , where @xmath454}{\longrightarrow } { \mathbb p}^2 $ ] . we have @xmath455 , where @xmath456 is the degree of the defining polynomial @xmath68 of @xmath79 and @xmath163 is the defining polynomial of @xmath134 . since @xmath129 is a quasihomogeneous triple , bezout s theorem and lemma [ lem : admilnors ] imply that @xmath457 and hence @xmath458 by lemma [ lem : hpconic ] , this is exactly the hilbert polynomial of the sheaf @xmath459 associated to @xmath460 . [ lem : moduleconicexact ] for a quasihomogeneous triple such that @xmath134 is free with exponents @xmath461 , @xmath462 is exact . as we ve seen , @xmath463 . with the assumption on @xmath134 , @xmath464 vanishes for all @xmath246 , and exactness follows as in the proof of lemma [ lem : lineexact ] . theorem [ thm : adconic ] will follow from the next two lemmas . [ lem : conic1 ] let @xmath129 be a quasihomogeneous triple , with @xmath344 . if @xmath134 is free with exponents @xmath461 , then 1 . if @xmath345 then @xmath79 is free with @xmath347 . 2 . if @xmath348 and @xmath465 , then @xmath79 is free with @xmath466 . 3 . if @xmath348 and @xmath467 , then @xmath79 is not free . it follows from the computations in the proof of lemma [ lem : hpconic ] that * if @xmath348 , then @xmath468 . * if @xmath345 , then @xmath469 . combining these results yields the hilbert series of @xmath273 . case 1 : @xmath345 . by lemma [ lem : moduleconicexact ] , @xmath470 since @xmath281 , this means that there exist minimal generators @xmath471 with @xmath472 and @xmath473 . suppose @xmath474 basis for @xmath283 with @xmath12 the euler derivation and @xmath475 . we now use that @xmath288 . * @xmath476 . since @xmath477 , @xmath478 for some @xmath479 . then @xmath480 is a basis for @xmath283 , so by saito s criterion @xmath481 is a basis for @xmath482 . * . then @xmath484 , where @xmath485 constants , not both zero . if @xmath486 , then @xmath487 is a basis for @xmath283 , so by saito s criterion @xmath488 is a basis for @xmath482 . * . then @xmath490 , where @xmath491 is a constant and @xmath492 is a linear form , not both zero . if @xmath493 then @xmath494 . since @xmath59 is irreducible , then @xmath495 , and so @xmath496 is of degree @xmath497 . this is inconsistent with the hilbert series of @xmath273 . so @xmath498 , and so @xmath480 is a basis for @xmath283 , and again by saito s criterion @xmath481 is a basis for @xmath482 . . then @xmath500 , where @xmath501 is a constant and @xmath502 is a quadratic form , not both zero and @xmath503 , where @xmath504 is a constant and @xmath505 is a quadratic form , not both zero . if @xmath506 , then either @xmath507 or @xmath496 , a contradiction ( because @xmath508 ) . therefore @xmath509 , contradicting the fact that @xmath510 are minimal generators of @xmath273 . so if @xmath511 , then @xmath512 is a basis for @xmath283 , and so by saito s criterion @xmath513 is a basis for @xmath482 . * @xmath514 . then @xmath500 , where @xmath501 is a constant and @xmath502 is a polynomial , not both zero and @xmath503 , where @xmath504 is a constant and @xmath505 is a quadratic form , not both zero . if @xmath506 , then @xmath515 and @xmath516 , @xmath517 nonzero constant , and the argument used above yields a contradiction . so @xmath498 or @xmath486 . applying saito s criterion yields the desired result . .1 in case 2 : @xmath518 . by lemma [ lem : moduleconicexact ] , @xmath519 this implies there exist degree @xmath99 minimal generators @xmath520 . suppose @xmath474 is a basis for @xmath283 where @xmath12 is the euler derivation and @xmath521 . so @xmath522 and @xmath523 , where @xmath524 are linear forms , and for any @xmath525 , @xmath526 can not be simultaneously zero . hence @xmath527 . but @xmath528 is in @xmath136 and @xmath529 , else @xmath530 is nonzero , which is inconsistent with the hilbert series . hence @xmath531 , where @xmath491 is a constant . if @xmath532 , then @xmath533 or @xmath534 , where @xmath535 are constants , and that @xmath536 and @xmath537 . if @xmath533 , and @xmath538 we get @xmath539 . since @xmath540 ( else @xmath541 ) then @xmath542 implies @xmath543 , yielding a degree @xmath215 derivation in @xmath544 , a contradiction . if @xmath545 , then @xmath121 and @xmath28 are not minimal generators , also a contradiction . if @xmath546 , then we find @xmath547=cc\det[e,\theta_1,\theta_2]$ ] , and saito s criterion shows that @xmath548 is a basis for @xmath341 . .1 in case 3 : @xmath549 . by lemma [ lem : moduleconicexact ] , @xmath550 since @xmath551 , there is no cancellation in the numerator , hence @xmath273 can not be free . [ lem : conic2 ] let @xmath129 be a quasihomogeneous triple , with @xmath344 . if @xmath79 is free , then 1 . if @xmath552 and @xmath553 , then @xmath134 is free with @xmath554 . 2 . if @xmath555 and @xmath556 , then @xmath134 is free with @xmath557 . 3 . if @xmath558 and @xmath559 with @xmath560 , then @xmath134 is not free . as in lemma [ lem : lines2 ] , apply @xmath305 to the exact sequence @xmath561 since @xmath562 is supported on the conic @xmath59 , @xmath563 . the assumption that @xmath273 is free implies that @xmath564 . this yields an exact sequence : @xmath565 as @xmath273 free with known exponents , so also is @xmath566 , and the hilbert series is known . the proof of lemma [ lem : hpconic ] provides a free resolution of @xmath567 , which allows us to compute @xmath568 . combining everything yields the hilbert series of @xmath569 , and the result follows as in the previous analysis . we close with a pair of examples which show that in the cl case , terao s conjecture that freeness is a combinatorial invariant of an arrangement is false . [ exm : last ] let @xmath324 be given by @xmath570 @xmath571 is tangent to both @xmath572 and @xmath573 at the point @xmath574 ; @xmath572 and @xmath573 have two other points in common . adding the line @xmath575 passing through @xmath576 to @xmath324 yields a quasihomogeneous , free cl arrangement @xmath79 , with @xmath577 the line @xmath578 passes through @xmath576 , and misses the other singularities of @xmath324 . the cl arrangement @xmath579 is combinatorially identical to @xmath79 , but @xmath134 is not quasihomogeneous , and not free : @xmath580 [ exm : noterao ] let @xmath581 be the union of the five smooth conics : @xmath582 @xmath581 has 13 singular points , all ordinary . at 10 of these points only two branches of @xmath581 meet , while at the points @xmath583 , all five conics meet . the milnor and tjurina numbers agree at all singularities except @xmath82 , where @xmath84 and @xmath83 . adding lines @xmath584 connecting @xmath583 yields a free cl arrangement @xmath79 , with @xmath585 . .05 in next , let @xmath586 be the union of the following five smooth conics : @xmath587 @xmath586 is combinatorially identical to @xmath581 , but at the points @xmath588 where all the branches meet , @xmath84 and @xmath83 . adding the lines connecting these three points yields an cl arrangement @xmath589 which is combinatorially identical to @xmath79 but _ not free _ ; the free resolution of @xmath590 is : @xmath591 as was pointed out by the referee , the complements of arrangements @xmath33 and @xmath592 are homeomorphic ( via a cremona transformation centered on the three multiple intersection points ) to the complements of a pair of line arrangements consisting of eight lines in general position . the moduli space of such objects is connected , so the complements are rigidly isotopic , hence homeomorphic . so freeness is also not a topological invariant . 1 . as noted in 1.2 , for the complement @xmath208 of an cl arrangement in @xmath593 the betti numbers @xmath594 and @xmath595 depend only on the combinatorics , and so if @xmath208 is quasihomogeneous and free , there is a version of terao s theorem , which we leave for the interested reader . 2 . in the examples above , the jacobian ideals are of different degrees , so are not even members of the same hilbert scheme . do there exist cl arrangements with isomorphic intersection poset _ and _ singularities which are locally isomorphic , one free and one nonfree ? do there exist counterexamples where all singularities are quasihomogeneous ? as shown by example 2.3 , quasihomogenity is not a necessary condition for freeness of cl arrangements . however , without this assumption , the sequences in propositions 2.8 and 3.8 may not be exact , which means that any form of addition - deletion will require hypotheses on higher cohomology . * acknowledgments * : macaulay2 computations were essential to our work . we also thank an anonymous referee for many useful suggestions , in particular for pointing out that we should remove one of our original conditions ( that @xmath596 has only ordinary singularities ) .

let @xmath0 be a collection of smooth rational plane curves . we prove that the addition - deletion operation used in the study of hyperplane arrangements has an extension which works for a large class of arrangements of smooth rational curves , giving an inductive tool for understanding the freeness of the module @xmath1 of logarithmic differential forms with pole along @xmath2 . we also show that the analog of terao s conjecture ( freeness of @xmath1 is combinatorially determined if @xmath2 is a union of lines ) is false in this setting . [ section ] [ defn0]proposition [ defn0]conjecture [ defn0]theorem [ defn0]lemma [ defn0]corollary [ defn0]example

Colombo (AFP) - Sri Lanka has detained a female British tourist for having a Buddha tattoo on her right arm and ordered her deportation, police said Tuesday. The unidentified woman was arrested at the country's main international airport on Monday and appeared before a magistrate who ordered her deportation, police said in a statement. The statement said she had an image of the Buddha seated on a lotus flower tattooed on her right arm. "She was taken before the Negombo magistrate who ordered her to be detained prior to deportation," it said, adding that she was arrested shortly after her arrival on a flight from neighbouring India. It did not say what charges were brought against her, but Sri Lanka barred another British tourist from entering the island in March last year for showing "disrespect" to Buddhism by having a Buddha tattooed on his arm. Sri Lanka, a majority Buddhist nation, is highly sensitive to perceived threats to the religion. In August 2012, three French tourists were sentenced to six months in jail, which was suspended for five years, for kissing a Buddha statue in what the authorities considered was a sign of disrespect. Sri Lanka prevented US rap star Akon from visiting in 2010 over one of his music videos which featured scantily clad women dancing in front of a Buddha statue. It was not immediately clear where the detained British woman would be deported to. ||||| A British tourist is to be deported from Sri Lanka, after she was arrested at Bandaranaike International Airport in the capital Colombo for having a tattoo of Buddha on her arm. Naomi Michelle Coleman had arrived at the airport from India, and was detained when the tattoo of a Buddha seated on a lotus flower was spotted on her right arm, according to Sri Lankan police officials. After her arrest Coleman, appeared before a magistrate who ordered her deportation, which will take place “very soon…tomorrow or the day after tomorrow,” a police spokesman said. He added that the 37-year-old was arrested for “hurting others' religious feelings”. Buddhism is the religion of the country's majority ethnic Sinhalese and tattoos using Buddhist iconography are regarded as culturally insensitive. Her arrest follows a ban imposed in 2011 by Thailand's Culture Ministry which ruled that foreign tourists in Sri Lanka should be barred from getting tattoos of Buddha. A Sri Lankan sweeper cleans in front of a Buddha statue in Colombo, the city where Ms Coleman was arrested. In 2010, R&B star Akon was refused a Sri Lankan visa and had to apologise to Sri Lankan Buddhists after his video for Sexy Chick, which featured a pool party in front of a Buddha statue, caused offence and protests in the nation. A spokeswoman for the Foreign and Commonwealth Office confirmed they were dealing with the case of a detained British national. She said: "We are aware of the detention of a British national in Sri Lanka on April 21. We are providing consular assistance." Additional reporting by PA

– A British woman learned the hard way that it's not a good idea to visit Sri Lanka if you have a visible Buddha tattoo. Tourist Naomi Michelle Coleman, 37, was arrested after arriving from India at Sri Lanka's main international airport yesterday; she was taken before a judge, who ordered her to be deported. The tattoo, on her right arm, shows the Buddha sitting on a lotus flower, AFP reports. Sri Lanka has a Buddhist majority, and a police spokesperson says she was detained for "hurting others' religious feelings," the Independent notes. She's expected to be deported within days; the same thing happened to a male tourist last year.

Robin Thicke Blurred Sonogram Lines April's Pregnant with a Girl!!! Robin Thicke's Girlfriend April Love Geary Pregnant with Girl Exclusive Details Robin Thicke is about to be a father again, with a girlfriend who is barely able to legally drink. 22-year-old April Love Geary is 3 months pregnant with a girl ... the baby is due March 1. 40-year-old Robin has been dating April for 3 years ... shortly after his wife, Paula Patton, filed for divorce. Robin and Paula are still not divorced, and they have had an on-and-off custody war over their 7-year-old son, Julian. By the way, we're told Robin and April told Julian this week and he's "super excited for a little sister." March 1 would have been Alan Thicke's 70th birthday. ||||| Robin Thicke and April Love Geary are expecting! The model announced her pregnancy on Instagram Thursday, writing: “Robin and I are very excited to share with you all that we’re having a baby! The due date is March 1st, [Robin’s late father] Alan’s birthday!” In addition Geary, 22, shared a photo of her sonogram, which was dated Aug. 14. TMZ reports that the baby is a girl. Thicke, 40, is already dad to 7-year-old Julian Fuego, his son with ex-wife Paula Patton. The parents-to-be started dating in the months following his separation from the actress in February 2014. Patton filed for divorce in October 2014 and in March 2015, their divorce was finalized. Earlier this year, the former couple were embroiled in a lengthy custody dispute, which now appears to be resolved. Dave M. Benett/amfAR15/WireImage Thicke and Geary made their first public appearance together at the Cannes Film Festival in May 2015 after dating for over a year. On Wednesday, Geary shared a bikini photo and first look at her baby bump during her vacation in Hawaii. Both Thicke and Geary frequently post about their romance on social media and she has previously joked about the couple’s 18-year-age gap in April. Put your celeb and pop culture knowledge to the test and download PEOPLE and Zynga’s Crosswords with Friends!

– Robin Thicke is expecting his second child, his first baby with girlfriend April Geary. Geary announced the pregnancy with an ultrasound photo on Instagram, noting that the little one is due March 1—the birth date of Thicke's late father, Alan. Thicke, 40, has a 7-year-old son with ex-wife Paula Patton. The singer started dating Geary, 22, soon after his 2014 split with Patton, People reports. According to TMZ, their baby is a girl.

based on structural features , the cytokines have been grouped into several families such as interleukin ( il ) , interferon ( ifn ) , tumor necrosis factor ( tnf ) , and transforming growth factor ( tgf ) family . the homologies among genes from different families are quite limited . according to sequence homologies , similarities of receptor chain , and functional properties , ils are further divided into il-1 , il-10 , il-12 , and il-17 families . il-10 family consists of nine members : il-10 , il-19 , il-20 , il-22 , il-24 , il-26 , il28a , il-28b , and il-29 . in mammals these members clustered , respectively , in three genomic loci : il-10 locus in which il-10 , il-19 , il-20 , and il-24 are included ; ifn- locus in which il-22 and il-26 are included ; ifn- locus in which il-28a , il-28b , and il-29 ( also called ifn-2 , ifn-3 , and ifn-1 , resp . ) are included . these il-10 family members in mammals are involved in diverse immune regulation and host defense during bacterial and viral infection and also were important for the differentiation and proliferation of immune cells , such as t cell , b cell , and natural killer ( nk ) cell . among these il-10 family members , il-10 was originally called cytokine synthesis inhibitory factor ( csif ) , which was firstly cloned from th2 clones , because of its inhibition on the production of several cytokines , such as ifn- . subsequently , it was renamed as il-10 and found to be expressed by the cells involved in innate and adaptive immunity , including nk cells , dendritic cells ( dcs ) , macrophages , mast cells , neutrophils , cd4 + and cd8 + t cells , and b cells [ 7 , 8 ] . several immunostimulants , such as lps , polyi : c , phytohaemagglutinin ( pha ) , and phorbol 12-myristate 13-acetate ( pma ) , could enhance the expression of il-10 in the above - mentioned cells . to data , several il-10 family members have been identified from lower vertebrates . in fish il-10 and il-20l clustered in the il-10 locus . the latter might be the ancestral that gave rise to il-19 , il-20 , and il-24 genes . fish il-22 and il-26 genes were in ifn- locus , being similar to those in mammalian . in amphibian , two il-10 loci , that is , ifn- locus and ifn- locus , have been well characterized , with ifn- locus containing il-22 and il-26 genes and ifn- locus ifn1 - 5 genes . however , information about the il-10 locus in amphibian was still blank . functional study in fish revealed that the il-10 network in lower vertebrates was quite complex . for example , two trout il-10s ( il-10a and il-10b ) possessed different expression pattern after stimuli stimulation and bacterial infection . goldfish il-10 could downregulate the expression of the proinflammatory cytokines il-1 , il-8 , and tnf- and also il-10 itself , indicating fish il-10 might be an anti - inflammatory cytokine . african clawed frog ( xenopus tropicalis ) is the model animal of amphibian . due to its special evolutionary position , it has long been used to gain better appreciation of the evolution of the complex immune system . to provide more information on the evolution of il-10 family , the frog il-10 gene was cloned and structurally analyzed . also , the interleukins in frog il-10 locus were identified . and on this basis a comprehensive phylogenetic analysis was implemented in order to deepen the understanding of the evolution relationships among the various il-10 family members in vertebrates . to identify the frog il-10 gene , human il-10 and chicken il-10 were used to query the genomic database of x. tropicalis ( http://www.ensembl.org/ ) by tblastn program . the obtained genomic sequences were further analyzed using genscan and fgenesh+ program to get the putative exon and intron boundary . the predictive genes were searched against the national center for biotechnology information ( ncbi ) database ( http://blast.ncbi.nlm.nih.gov ) using blastp software . total rna was extracted from frogspleen using trizol reagent ( invitrogen , usa ) and transcripted into cdna using superscript ii reverse transcription system ( invitrogen , usa ) according to the manufacturer 's instructions . the full cdna sequence of frog il-10 was obtained by using 3- and 5-race pcr method with the synthesized cdna as template . the primers used for 3- and 5-race were designed based on the predicted results from genscan and fgenesh+ analysis . the primers for 5-race were upm / il10 - 5rout ( first round ) and upm / il10 - 5rin ( second round ) and upm / il10 - 3fout ( first round ) and upm / il10 - 3fin ( second round ) for 3-race ( table 1 ) . pcr was carried out in 25 l reaction system as follows : 125 m of each dntp , 0.2 m of each primer , 2.5 l 10 taq buffer , 12 u ex taq polymerase ( takara , japan ) , 18.1 l sterile h2o , and 1 l cdna template according to the standard protocol . pcr amplification was conducted under the following conditions : an initial denaturation step at 94c for 5 min , followed by 6 cycles of 30 s at 94c , 30 s at 64c , and 1 min at 72c , 30 cycles of 30 s at 94c , 30 s at 62c , and 1 min at 72c , and finally an extension step at 72c for 10 min . the products of first round pcr were 1 : 100 diluted with water and then used as the template for the second round pcr . 10 l of second round pcr products was size - fractioned by 1.5% ( w / v ) agarose gel electrophoresis and stained with ethidium bromide . the desired pcr products were ligated into pmd18-t vectors ( takara , japan ) and sequenced using the dideoxy chain termination method on an automatic dna sequencer ( abi applied biosystems mode 377 ) . the molecular weight and the net charge of the protein were calculated by protparam program ( http://ca.expasy.org/tools ) . the multiple protein sequence alignment was performed using clustal w program ( version 1.83 ) . the neighbor - joining ( n - j ) phylogenetic tree was constructed using jones - taylor - thornton ( jtt ) model within mega6 software . the signal peptide and the n - glycosylation sites were predicted using signalp ( v2.0 ) and netglyc 1.0 server , respectively . the template used for modeling was determined by searching in the genesilico metaserver , pdbblast , and pcons.net , with frog il-10 amino acid sequence as query . also , the template was confirmed by sequence - structure alignment using fugue ( find homologs of uncharacterized gene products using environment - specific substitution tables ) program in the homologous structure alignment database ( homstard ) , in which the target protein was clustered into homologous families and the top z - score against the cut - off score ( z - score > 6.0 ) was considered the optimum template for modeling . after validating the template for modeling , the models were generated by swiss - pdb server ( http://swissmodel.expasy.org/ ) . energy minimization of the obtained model was done in swiss - pdb viewer using a harmonic constraint of 100 kj mol . the quality of the model was checked by procheck and errat in saves server ( http://nihserver.mbi.ucla.edu/ ) . after obtaining the structural model of frog il-10 , explicit solvent md simulation was performed using gromacs ( groningen machine for chemical simulations ) 4.0 package on an inspur , 12 ghz pc equipped with the red hat 6.0 environment to further investigate the stability of this model . briefly , the frog il-10 protein was solvated by 17,297 water molecules in an octahedral box with 1.0 nm edges from the molecular boundary . nine cl ions were added to the frog il-10 model with a net positive charge of + 9 to obtain a neutral system . the configuration was energy minimized using the steepest descent algorithm ( maximum number of steps : 4,000 ) to remove steric conflicts between the protein and water molecules . the energy - minimized models were stimulated for 100,000 steps for a total of 200 ps under 300 k using position - restrained md in npt conditions . snapshots of the trajectory were taken every 1 ps . the final md of 5,000,000 steps was carried out for 10,000 ps ( 10 ns ) using the particle mesh ewald ( pme ) electrostatics method under npt conditions . healthy clawed frogs ( x. tropicalis ) were obtained from the institute of genetics and developmental biology , chinese academy of sciences ( beijing , china ) , and maintained in a freshwater tank at 23c under natural photoperiod and fed with pork liver twice per day . tissue samples of heart , liver , kidney , spleen , stomach , and intestine were collected from three healthy frogs . the same tissues from three frogs were mixed together for rna preparation using trizol reagent and cdna was synthesized with primescript rt reagent kit ( takara , japan ) according to the manufacturer 's instructions . the cdna fragments of frog il-10 and -actin were amplified by rt - pcr and confirmed by sequencing . amplicons were gel purified , and serial tenfold dilutions were run along with the cdna test samples on the same 96-well pcr plate as quantitative standard . the relative expression of frog il-10 in various tissue samples was normalized to the expression of -actin . to characterize the change of frog il-10 transcripts after lps stimulation , three frogs were injected intraperitoneally ( i.p . ) with lps ( 150 g/100 g body weight ) and the frogs as control were injected with the same volume of pbs solution . animals were anesthetized and killed at 24 h after injection . then tissue collection , rna extraction , and cdna synthesis were conducted as described above . in the present study , the sampling time was determined according to our previous research . the change of gene expression after lps stimulation was expressed as fold change and calculated as described in our previous study [ 13 , 14 ] . the data of real - time quantitative pcr were analyzed with the origin 6.0 software . a student 's t - test was applied to analyze the significance of fold change , with p value less than 0.05 considered as statistically significant difference . the full - length sequence of the frog il-10 cdna ( genbank accession number ef104912 ) comprised a 5 terminal untranslated region ( utr ) of 159 bp , an open reading frame ( orf ) of 519 bp , and a 3-utr of 567 bp . no attta sequence was observed in the 3-utr , which might involve in the shortening of the half - life of several cytokines and growth factors . the size of the four introns was 1836 bp , 1021 bp , 609 bp , and 2183 bp , respectively , which was a little larger than the counterpart in human il-10 or zebrafish il-10 . the typical intron splice motifs , that is , gt and ag , were observed , respectively , at the 5- and 3-end of each intron . the putative protein of frog il-10 was 172 amino acids in length , containing a 19 a.a . signal peptide at its n - terminus . the theoretical molecular weight and the isoelectric point ( pi ) of the mature peptide of frog il-10 were 15.08 kda and 7.92 , respectively . two conserved il-10 family signature motifs , l-[filmv]-x(3)-[ilv]-x(3)-[filmv]-x(5)-c - x(5)-[ilmv]-[ilmv]-x(3)-l - x(2)-[iv]-[filmv ] and ka - x(2)-e - x - d-[ilv]-[fly]-[filmv]-x(2)-[ilmv]-[ekqz ] , were found to manifest as llqddllqefkgnlgcqsvsetirfyleevl and kamgefdilidyie in frog il-10 . two extra cysteine residues at the n - terminals of fish il-10 were not found in frog , bird , and mammalian il-10s ( figure 2 ) . the frog il-10 shared the highest identity with chicken il-10 ( 58.3% ) , followed by 56.5% with human il-10 and 41.7% with zebrafish il-10 ( table 2 ) . by searching the genesilico metaserver , pdbblast , and pcons.net server , the human il-10 crystal structure ( pdb code : 2ilk ) at 1.6 resolution this was also confirmed by a higher z - score of 25.38 derived from the sequence - structure alignment between frogil-10 and template using the fugue software . the high identity between a.a . sequences of frog il-10 and template also confirmed that it was reasonable to do modeling using comparative modeling method . the model of frog il-10 was generated with swill - pdb server and the quality of the resultant model was evaluated with procheck and errat software . the procheck analysis showed that the phi - psi angles of 89.9% of the residues were in most favored regions , 7.1% in the additional allowed regions , 1.9% in generously allowed regions , and only 1.0% in disallowed regions . errat program showed the overall quality factor of the frog il-10 model was 96.31 , which was more than 95% , indicating high resolution of structure . the predicted spatial structure of frog il-10 possessed six -helices , similar to that of human il-10 monomer . however , there were some slight differences between the two proteins ; for example , helix a and helix c of frog il-10 were a little shorter which results in a longer ab loop and cd loop ( figure 3(a ) ) . md analysis showed that the rmsd of frog il-10 model became stable at 5 ns after simulation ( figure 3(b ) ) . mean rmsd and average rmsf ( root mean square fluctuation ) of frog il-10 were 0.8146 0.1744 nm and 0.3618 0.2042 nm , respectively . real - time pcr was performed to examine the tissue expression pattern in healthy and lps stimulated frogs . in healthy frog , il-10 was highly expressed in kidney , moderately in spleen and intestine , and slightly in heart , liver , and stomach ( figure 4(a ) ) . after lps stimulation for 24 h , the expression of frog il-10 was apparently induced in liver , spleen , kidney , intestine , and stomach , showing 7.5- , 17.3- , 13.6- , 10.4- , and 5.3-fold changes , respectively ( p < 0.05 ) ( figure 4(b ) ) . based on in silico analysis , we totally identified two ils from the frog il-10 locus ( scaffold 629 ) which are named as il-10 and il-20 . many conserved genes , for example , mapkapk2 , dyrk3 , and eif2d , highly linked with il-10 locus were found in all analyzed species . there were four ils ( il-10 , -19 , -20 , and -24 ) in the human il-10 locus and also il-10 and -19 in chicken il-10 locus , but without il-20 and -24 . fish il-10 locus also contained two ils , merely being named as il-10 and il-20l ( figure 5 ) . to further elucidate the evolution relationships of il-10 family members , a phylogenetic tree was constructed using all the frog il-10 family members except ifn-s and il-10 family members from fish and higher vertebrates . it was clear that the il-10 family members were mainly separated into four clusters with high bootstrap values , that is , il-22 , il-26 , il-10 , and il19/20/24 clusters . each of il-22 , il-26 , and il-10 clusters contained all counterparts from fish , frog , and mammals . the il19/20/24 cluster was further divided into three main clades : fish il-20l clade , il-19/20 clade , and mammal il-24 clade . the il-19/20 homologue newly identified from frog was grouped into the il19/20/24 cluster and formed a sister group with all other cluster members ( figure 6 ) . in the present study , the frog il-10 gene was cloned , and its expression and 3d structure were also analyzed . first , frog il-10 contained conserved amino acid residues and motifs that are essential for the bioactivity of il-10 , for example , the isoleucine residues at positon 87 ( i ) , which has been proved to be necessary for immunostimulatory function of human il-10 . substitution of isoleucine with alanine can abrogate the immunostimulatory activity of il-10 on thymocytes , mast cells , and alloantigenic responses while preserving immunosuppressive activity is concerned with the inhibition of ifn- production and the prolongation of cardiac allograft survival . this residue was also found in frog il-10 , suggesting that frog il-10 might possess similar immunostimulatory functions . also , the four conserved cysteine residues , known to form two disulphide bonds and to be essential for maintaining the structure and bioactivity of human il-10 , were found in frog il-10 ( figure 2 ) . two extra cysteine residues existing in fish il-10 , for example , cys27 and cys32 in zebrafish il-10 , but being nonexistent in il-10s from higher vertebrates , were absent in frog il-10 , suggesting that these two cysteine residues should be fish specific . an alternative scheme of disulphide bonds was predicted in fish il-10 by disulphide prediction software , disulfind , but the comparative modeling analysis of carp il-10 suggested that the two cysteine residues could not form any significant bonds . secondly , frog il-10 possessed the conserved 3d structure , similar to that of human il-10 , consisting of six -helices termed a , b , c , d , e , and f ( figure 3(a ) ) . the structural model of frog il-10 in our study was confirmed to be acceptable based on the results of molecular dynamics analysis ( figure 3(b ) ) . it had been proved that these six -helices in human il-10 are involved in associating with the other monomer to form two interpenetrating domains and that n - terminus , helix a , ab loop , de loop , and helix f of human il-10 were active sites for interacting with its receptors [ 32 , 33 ] . that the conserved six -helices also existed in frog il-10 suggested that the monomer of frog il-10 might be firstly activated to form homodimer so as to bind to its receptors . however , shorter helix a and helix c and longer ab loop and cd loop were observed in frog il-10 . in addition , frog il-10 possessed the same genomic organization as all reported il-10s , containing five exons and four introns ( figure 1 ) . lowly expression of frog il-10 gene in liver , heart , and stomach tissues was in agreement with the results of the study on trout il-10 . the relatively high level of frog il-10 expression occurred in immune related tissues , for example , intestine and spleen ( figure 4(a ) ) , suggesting that the frog il-10 plays some roles under basal conditions . after lps stimulation , the expression of frog il-10 was upregulated greatly in the tissues , including liver , spleen , kidney , intestine , and stomach ( figure 4(b ) ) , indicating that frog il-10 should act an important role for resistance against bacterial infections . the upregulation of frog il-10 expression in intestine and stomach also suggested the il-10 might be involved in mucosal immune response in amphibian . the number of il genes and their types in the il-10 loci from various species were different , for example , four ils named as il-10 , -19 , -20 , and -24 in mammalian il-10 locus , il-10 and -19 in chicken il-10 locus , and il-10 and il-20l in fish il-10 locus ( figure 5 ) . in the present study , we identified two interleukins in frog il-10 locus , that is , il-10 and the homologue of il-20/19 . this homologue identified newly contained six conserved cysteine residues , which were found in mammalian il-19 and -20 and fish il-20l [ 11 , 35 ] . on the contrary , there were four cysteine residues in most of il-10s and two in human il-24 ( figure 2 ) . its identities of 37.9% and 35.7% , respectively , with human il-20 and zebrafish il-20l were slightly higher than the values of identity with frog il-10 and other il-10 family members , ranging from 23.9% to 32.4% ( table 2 ) . the finding of il-19/20 homologue in frog suggested that the divergence of il-19 and il-20 might occur after amphibian appearance during biological evolution . of course , the function and the potential receptors of the homologue should be further studied to reveal its exact evolutionary position .

interleukin-10 ( il-10 ) is a pleiotropic cytokine that plays an important role in immune system . in the present study , the il-10 gene of african clawed frog ( xenopus tropicalis ) was first cloned , and its expression pattern and 3d structure were also analyzed . the frog il-10 mrna encoded 172 amino acids which possessed several conserved features found in il-10s from other species , including five - exon / four - intron genomic structure , conserved four cysteine residues , il-10 family motif , and six -helices . real - time pcr showed that frog il-10 mrna was ubiquitous expressed in all examined tissues , highly in some immune related tissues including kidney , spleen , and intestine and lowly in heart , stomach , and liver . the frog il-10 mrna was upregulated at 24 h after lps stimulation , indicating that it plays a part in the host immune response to bacterial infection . another il , termed as il-20 , was identified from the frog il-10 locus , which might be the homologue of mammalian il-19/20 according to the analysis results of the phylogenetic tree and the sequence identities .

When Desiree Linden crossed the finish line on Monday morning, there were tears of joy and celebration for the first American woman to win the Boston Marathon in more than three decades. Four minutes and 10 seconds later, when the second-place finisher, cold and soaking wet from the April rain, had completed the race, there were mostly questions. Who was Sarah Callister Sellers? How did a woman with a full-time job and no racing sponsorships manage to beat all but one of some of the best marathon runners in the world? “I didn’t even know it was a possibility,” she told the Boston Globe after the race. “I was trying to ask officials what place I was in. I had no idea when I crossed the finish line.” Weber State track coach Paul Pilkington had been watching the race on television when he heard the announcers say Sellers had just finished in second place — and he had some questions, too. “I kept hitting refresh on the race results,” he recalled. “Did they miss somebody? Did I miss somebody?” Then Pilkington let out a cheer for Sellers, the former Ogden High and Weber State track standout, who was suddenly no longer a mystery to the running world. “I think I’m going to wake up and this will be a dream,” Sellers said after the race. Sellers was a standout runner at Ogden High from 2005-09. But even retired Ogden track coach Don Hall, who watched the race on television Monday, was surprised to see his former star runner finish second in Boston. “I was stunned, shocked, amazed,” he said. “I was jumping up and down.” She went on to be a nine-time Big Sky champion during her career at Weber State from 2009-12. She won the 5,000 meters and 10,000-meter title three times each at the Big Sky outdoor championships and won the 5,000 meters twice and the 3,000 meters once at the indoor championships. But Sellers’ collegiate career was cut short when she broke her foot running a race during her junior season, Pilkington said. “I always felt like her career should have ended better,” the coach said. “It’s great to have her reach this level now.” Desiree Linden, of Washington, Mich., celebrates after winning the women's division of the 122nd Boston Marathon on Monday, April 16, 2018, in Boston. She is the first American woman to win the race since 1985. (AP Photo/Charles Krupa) Sellers ran her first marathon in September of last year in Huntsville — and she set a course record in the process. After that, she set her sights on Boston with hopes of a top-15 finish that would automatically earn her a spot at the Olympic trials in two years. Sellers now lives in Tucson, Ariz., with her husband, Blake Sellers, and works as a nurse anesthetist. But she still relies on Pilkington for coaching. She wakes up at runs each day at 4 a.m. before work. She runs about 85 miles each week, including a number of sustained runs — 20-milers at a 6-minute pace. Then on Mondays, she calls Pilkington to discuss her training and make adjustments. With rain and strong winds in the forecast for Monday, Pilkington and Sellers spoke over the weekend to dial in her strategy for the race. The coach instructed her to slow her pace slightly in the difficult conditions. “She has the right mentality. She’s very tenacious and tough mentally. In such bad conditions today, that played to her benefit,” Pilkington said. “… She ran a very smart race. You look at the field, a lot of them those conditions took too much of them.” Yuki Kawauchi passed defending champion Geoffrey Kirui in Kenmore Square to win the men’s race in an unofficial 2:15:58 and earn Japan’s first Boston Marathon title since 1987. Kirui slowed and stumbled across the Copley Square finish line 2:25 later, followed by Shadrack Biwott and three other U.S. men. Yuki Kawauchi, of Japan, wins the 122nd Boston Marathon on Monday, April 16, 2018, in Boston. He is the first Japanese man to win the race since 1987. (AP Photo/Elise Amendola) On the fifth anniversary of the finish line explosions that killed three and wounded hundreds more, Linden and Kawauchi led a field of 30,000 runners through a drenching rain, temperatures in the mid-30s and gusts of up to 32 mph on the 26.2-mile trek from Hopkinton. In Copley Square, crowds thinned and muffled by the weather greeted Linden, the California native who lives in Michigan, with chants of “U-S-A!” Linden — a two-time Olympian — finished the race in 2 hours, 39 minutes and 54 seconds. Sellers crossed the finish line in 2 hours, 44 minutes and 4 seconds. It was the first time two Americans have finished first and second in Boston since 1979. Her finish is the best ever by a native of Utah at the Boston Marathon. “I knew she was in very good shape,” Pilkington said. “But if you would have told me she was second at Boston, I would have said no way.” Sellers was in disbelief herself when she called her coach Monday, Pilkington said. “That’s the great thing about our sport,” he said. “It’s rare for something like this to happen. It’s a Cinderella story.” Sellers and her coach will now turn their attention to picking her next big race — possibly a marathon in Chicago, Berlin or New York next fall — as she continues her preparation for the Olympic trials. “She’s never going to be the unknown racer ever again,” Pilkington said. — The Associated Press contributed to this story ||||| Story highlights Monday's race was Sarah Sellers' second marathon Her second-place finish is tops by a Utah native (CNN) Desiree Linden made history at this year's Boston Marathon as the first American woman to win the storied race since 1985. What was more shocking, though, was the runner-up in the women's field Monday. In her second career marathon race, Sarah Sellers wasn't listed as one of the elite runners. According to The Wall Street Journal, she doesn't have any sponsors . Still, Sellers crossed the finish line in 2:44:04, a little more than 4 minutes behind Linden's time (2:39:54), qualifying for the US Olympic trials. The combination of the wind and rain made conditions difficult, and it was the coldest Boston Marathon in 30 years. But it was worth it: Sellers leaves Boston with $75,000 in prize money. "I think I'm going to wake up and this will be a dream," Sellers said. "It was a like a hurricane out there." Read More

– That an American female won the Boston Marathon for the first time since 1985 made headlines, but it's the woman who came in second who is grabbing them now. Eyes are shifting to Sarah Sellers, who finished 4 minutes and 10 seconds behind winner Desiree Linden with a time of 2 hours, 44 minutes, 4 seconds. But while Linden is a two-time Olympian, Sellers is a virtual unknown: A promising track career in college hit an early end due to a broken foot her junior year, reports the Salt Lake Tribune. She had only run one marathon prior, in Utah in September, in order to qualify for Boston. The 26-year-old has no sponsors, and did much of her training starting at 4am, before heading to her full-time job as a nurse anesthetist in Tucson, Arizona. CNN picks up this tweet from Kit Fox of Runners World as a sign of just how unexpected her win was: The first question she was asked in a post-race news conference was "Please introduce yourself. Tell us who you are." Sellers logs about 85 miles a week, and still relies on Weber State track coach Paul Pilkington for advice. She now walks away with $75,000 in prize money, which she says she and her husband will put toward their student debt. As for that first marathon in Huntsville, Utah, she didn't just win it: She set a course record.

measurements of strangeness production in heavy - ion collisions were originally conceived to be the smoking gun of quark gluon plasma ( qgp ) formation @xcite . it was argued that due to a drop in the strange quark s dynamical mass and increased production cross section , strangeness in the qgp would saturate on small time scales relative to a hadronic gas . twenty nine years since then , the production of strangeness continues to test our understanding of qcd in both p+p and heavy - ion collisions . in these proceedings , we review recent measurements of strange particle production at the star experiment . we first explore integrated yields in cu+cu and au+au collisions where production is expected to be dominated by low @xmath2 processes at rhic energies , then proceed to mid-@xmath3 spectra where fragmentation and recombination may compete . we then turn to strange particle @xmath4 and tests for non - equilibrium behaviour with respect to elliptic flow , then show test results for rhic s low energy program which will search for a possible critical point on the qcd phase diagram . finally , we show new results on strange particle fragmentation functions in p+p collisions . figure [ fig:1 ] shows the _ enhancement factor _ for strange particle yields in cu+cu and au+au @xmath5 gev collisions . assuming a thermally equilibrated qgp hadronises into a maximum entropy state , a test for strange quark saturation in the initial stages is provided by comparing the final hadron state yields to thermal model predictions from the canonical formalism @xcite . for all strange particles it is clear that for a given system , rises in the enhancement factor with @xmath6 are observed which is predicted by the canonical formalism . however , the enhancement factor appears to rise more rapidly in cu+cu collisions , and this is inconsistent with the canonical formalism which predicts the rise should just be controlled by @xmath7 independent of the collision system . that relies on a constant baryo - chemical potential and chemical freeze out temperature for both systems which has been shown @xcite . we also make comparisons to predictions from the ampt @xcite and epos @xcite models which have been shown to describe the bulk features of hadron production well for au+au @xmath5 gev collisions . the ampt model is based on hijing , and thus describes particle production in heavy - ion collisions via intra - nucleon string excitation and breaking ( soft ) , and mini - jet fragmentation ( hard ) where the excited nucleons fragment independently . the epos model describes particle production with core and corona contributions . the core occupies the high density region in the collision zone and aims to mimic various qgp behaviour . at a particular freeze - out density , the hadronisation is treated via statistical emission where strangeness production is over saturated ( @xmath8 ) . corona production occurs in the low density region and is a superposition of p+p collisions . both the ampt and epos models reproduce three key qualitative aspects of the data : rises in yields per @xmath6 for a given system , a faster rise in yields per @xmath6 for cu+cu collisions , and a merging in yields per @xmath6 for peripheral cu+cu and very peripheral au+au collisions . quantitatively , epos is nearly always closer to the measured data than ampt . figure [ fig:2 ] shows the enhancement factor for the @xmath9 particle in context of the @xmath10 , @xmath11 and @xmath12 enhancements . for both cu+cu and au+au collisions at energies of @xmath13 and @xmath14 gev , an above unity enhancement factor is observed which is also inconsistent with predictions from the canonical formalism @xcite , and this sits between the single and multi - strange values for au+au @xmath5 gev collisions . an alternative core - corona approach has been shown to describe the @xmath9 enhancement factors in au+au @xmath5 gev collisions quite well @xcite , as has a more recent implementation of the epos model @xcite . figure [ fig:3 ] shows thermal parameters extracted from particle ratios via the thermus model @xcite for p+p , cu+cu , and au+au @xmath5 gev collisions . in the left panel we observe that the chemical freeze - out temperature ( @xmath15 ) is independent of centrality and system , as mentioned previously . in the right panel we observe that the strangeness saturation factor ( @xmath16 ) , which characterises the deviation in strangeness production from thermal expectations , appears to lie on a common trend with respect to @xmath17 . strangeness saturation i.e. @xmath18 in both cu+cu and au+au appears to be reached at @xmath19 in this scheme . [ cols="^,^ " , ] @xmath1 measurements characterise the conversion from the initial state anisotropy to momentum anisotropy , and thus may give information on the degree of rescattering in heavy - ion collisions . by implementing the boltzman equation , transport theory can determine the degree of non - equilibrium behaviour @xcite . this is quantified via the knudsen number @xmath20 which is the ratio of the mean free path length to the system size . non - equilibrium @xmath1 can be expressed as follows : @xmath21 where @xmath22 is the initial state eccentricity and @xmath23 a constant . when @xmath24 , @xmath4 is fully hydrodynamic like , and when @xmath25 , @xmath4 is below hydro expectations as the effects of a finite mean free path and/or finite system size are felt by the system . the left panel of figure [ fig:5 ] shows @xmath3 integrated @xmath4 for strange and non - strange in cu+cu and au+au @xmath5 gev collisions . the right panel shows the same data divided by the expected hydro value at the respective system density . the fitted transport curve shows the knudsen number decreases with increasing density and does not reach zero for the highest densities where the measured @xmath1 is @xmath26 below hydro expectations . amongst other things , the apparent contradiction with earlier claims of ideal hydro behaviour results from eccentricity being better understood in heavy - ion collisions @xcite . various lattice qcd calculations predict a critical point where the qgp may hadronise via a first order phase transition @xcite . this motivates a possible low energy scan ( @xmath27 gev ) at rhic that aims to cover the most recent predictions of temperature and baryo - chemical potential where the critical point may occur . furthermore , as a collider experiment , star s constant acceptance with respect to beam energy gives it an advantage over its fixed target counterparts where other searches maybe carried out . earlier this year , star recorded @xmath28 events from au+au @xmath29 gev collisions as a feasibility test for low energy running . the results are shown in figure [ fig:6 ] for the @xmath30 and @xmath31 ratios . it is clear that star has already achieved global consistency with other experimental results . the same is found to be true for the integrated mid - rapidity @xmath32 , @xmath33 , and @xmath34 ratios , and the @xmath35 and @xmath31 ratios from au+au @xmath36 gev collisions recorded in 2000 @xcite . we finally turn to strange particle fragmentation functions measured in p+p @xmath5 gev collisions . these provide an essential reference for understanding strangeness production from jets in heavy - ion collisions , and offer constraints to various qcd inspired jet fragmentation models . figure [ fig:7 ] shows fragmentation functions for the charged hadron , @xmath37 , and @xmath38 particles at three different jet energies . the fragmentation function is expressed in terms of @xmath39 where @xmath40 is the reconstructed jet energy , and the respective probability function is normalised by the number of jets in the energy range studied . for a particular particle species , the integral of the function gives the mean number per jet over a chosen range in @xmath41 . there are two key observations to be made from the data in figure [ fig:7 ] for all jet energies . firstly , it was found that for the particle species studied , the mean @xmath41 violated a predicted mass ordering expected in qcd @xcite . secondly , for a hadron of @xmath42 gev / c , it was found that the @xmath43 ratio @xmath44 . since p+p events with higher values of @xmath45 are more likely to contain a hard scattered parton @xcite , this observation is supported by the fact that the inclusive mid-@xmath46 @xmath43 ratio approaches one with increasing @xmath45 @xcite . taken at face value , this readdresses the question of exactly what is a jet - like baryon / meson ratio , with the answer being crucial for heavy - ion studies in the mid-@xmath0 range . finally , it must be noted that the accuracy of each of the measurements behind the respective observations is still under evaluation . we have presented recent results for strange particle @xmath47 in cu+cu and au+au collisions and found for the collision energy of @xmath5 gev , both the epos and ampt models reproduce qualitative features of the data with epos doing better quantitatively . it was shown that baryon - meson differences occur for @xmath48 in cu+cu @xmath5 gev collisions , and that a recombination model describes the @xmath3 dependance of the @xmath49 ratio for central cu+cu collisions at the same energy . strange and non - strange particle @xmath4 were found to exhibit non - equilibrium behaviour for cu+cu and au+au @xmath5 gev at all centralities , and star s recent low energy run gave @xmath50 ratios consistent with other experiments . strange particle fragmentation functions were presented for p+p @xmath5 gev collisions , and these showed a breaking of the expected mean @xmath41 mass ordering and a mid-@xmath0 ( @xmath51 gev / c ) @xmath43 ratio of @xmath44 in jets for the kinematic range studied . 10 rafelski j and mller b 1982 _ phys . rev . lett . _ * 48 * 1066 koch p , mller b and rafelski j 1986 _ phys . * 142 * 167 timmins a ( star collaboration ) _ arxiv:0810.0017 _ hamieh s , redlich k and tounsi a , 2000 _ phys . b _ * 486 * 61 iordanova a ( star collaboration ) 2008 _ j. phys . g _ * 35 * 044008 takahashi j ( star collaboration ) _ these proceedings _ abelev b _ et al . _ ( star collaboration ) _ arxiv:0810.4979v1 _ lin z , ming ko c , li b , zhang b and pal s , 2005 _ phys . c _ * 72 * 064901 werner k 2007 _ phys . lett . _ * 98 * 152301 xu n ( star collaboration ) 2008 _ j. phys . g _ * 35 * 044031 becattini f , _ these proceedings _ ; becattini f and manninen j 2008 _ j. phys . g _ * 35 * 104013 aichelin j and werner k , _ wheaton s , cleymans j and hauer m 2008 _ comput . phys . commun . _ * 180 * 84 - 106 lamont m ( star collaboration ) 2006 _ j. phys . g _ * 32 * s105-s114 wang x 2008 ( star collaboration ) _ j. phys . g _ * 35 * 104074 abelev b _ ( star collaboration ) 2007 _ phys . lett . _ * 99 * 112301 alver b _ ( phobos collaboration ) 2006 _ phys . lett . _ * 96 * 212301 masui h ( star collaboration ) , _ these proceedings _ abelev b _ et al . _ ( star collaboration ) 2009 _ phys . c _ * 77 * 54901 gombeaud c and ollitrault j 2008 _ phys . c _ * 77 * 054904 yuting b ( star collaboration ) , _ these proceedings _ snellings r , _ these proceedings _ kumar l ( star collaboration ) , _ these proceedings _ heinz m ( star collaboration ) , _ arxiv:0809.3769v1 _ dokshitzer y , khoze v , fong c and webber b 1991 _ phys . b _ * 273 * 319 . adams j _ et al . _ ( star collaboration ) 2006 _ phys . d _ * 74 * 03200 abelev b _ et al . _ ( star collaboration ) 2007 _ phys . _ c * 75 * 064901

we present an overview of recent star results on strangeness production in p+p and heavy - ion collisions at rhic . in both cu+cu and au+au collisions we show the centrality dependencies of bulk yield and mid-@xmath0 spectrum measurements with new comparisons to theory . the latest @xmath1 results for strange particles are presented and prospects for strangeness production in the low energy scan program will be outlined . finally , we report new measurements of strangeness fragmentation functions for jets in p+p collisions .

the field of numerical relativity has matured to a stage where it is possible to simulate realistic systems of astrophysical interest . in this paper , we examine the global effects of viscosity on differentially rotating , relativistic stars . viscosity can have significant effects on the stability of neutron stars . for example , it can drive a secular bar instability in rapidly rotating neutron stars , as shown in newtonian gravitation @xcite and in general relativity @xcite . viscosity can suppress the @xmath1-modes @xcite and other gravitational - radiation driven instabilities , including the secular bar modes @xcite . viscosity also destroys differential rotation , and this can cause significant changes in the structure and evolution of differentially rotating massive neutron stars . differentially rotating neutron stars can support significantly more rest mass than their nonrotating or uniformly rotating counterparts , making `` hypermassive '' neutron stars possible @xcite . such hypermassive neutron stars can form from the coalescence of neutron star binaries @xcite or from rotating core collapse . the stabilization arising from differential rotation , although expected to last for many dynamical timescales , will ultimately be destroyed by magnetic braking and/or viscosity @xcite . these processes drive the star to uniform rotation , which can not support the full mass of the hypermassive remnant . this process can lead to `` delayed '' catastrophic collapse to a black hole , possibly accompanied by some mass loss . such a delayed collapse might emit a delayed gravitational wave signal detectable by laser interferometers . moreover , the collapse , together with any residual gas in an ambient accretion disk , could be the origin of a gamma - ray burst ( grb ) . both magnetic fields and viscosity can destroy differential rotation in a rapidly rotating star @xcite . simple estimates show that the magnetic braking ( alfvn ) timescale for a laminar field is much shorter than the timescale of molecular ( neutron ) viscosity in a typical massive neutron star . hence magnetic fields are expected to be the principal mechanism driving neutron stars toward rigid rotation . phase mixing arising from magnetic braking @xcite , or other possible magnetohydrodynamic instabilities @xcite might stir up turbulence . turbulent shear viscosity could then dominate the subsequent evolution . in this paper , we are primarily interested in identifying the global evolutionary consequences of shear viscosity in a relativistic star , independent of the detailed nature or origin of the viscosity . to explore the consequences of the loss of differential rotation in equilibrium stars , we study the secular evolution of differentially rotating relativistic stars in the presence of a shear viscosity . viscosity and magnetic fields have two things in common : ( 1 ) they both change the angular velocity profiles of a differentially rotating star , and ( 2 ) they both act on _ secular _ timescales , which can be many rotation periods . the latter inequality poses a severe challenge to numerical simulations using a hydrodynamic code . it is too taxing for a _ hydrodynamic _ code using an explicit differencing scheme to evolve a star for physical realistic secular timescales . to solve this problem , we artificially amplify the strength of viscosity so that the viscous timescale is short enough for numerical treatment . however , we keep the viscous timescale substantially longer than the dynamical timescale of the stars , so that the evolution of the star remains quasi - stationary . we then check the validity of our results by reducing the viscosity on successive runs and testing that the viscosity - induced physical behavior is unchanged ; rather , only the timescale changes and does so inversely with the strength of viscosity . a more detailed discussion of the expected scaling is presented in section [ justification ] @xcite . to study viscous evolution , we need to perform long simulations in full general relativity . typically , we evolve the stars in axisymmetry . this allows us to follow the secular evolution of the stars with high resolution in a reasonable amount of time . viscosity can , however , drive nonaxisymmetric instabilities when a star is rapidly rotating . to test for such instabilities , we also perform lower - resolution , three - dimensional ( 3d ) simulations on the most rapidly rotating stars we consider . for non - hypermassive neutron stars that are slowly and differentially rotating , we find that viscosity simply drives the whole star to rigid rotation . if the non - hypermassive neutron star is rapidly and differentially rotating , however , viscosity drives the inner core to rigid rotation and , at the same time , expels the material in the outer layers . the final system in this case consists of a rigidly - rotating core surrounded by a low - density , ambient disk in quasi - stationary equilibrium . our most interesting results concern the fate of hypermassive neutron stars . we numerically evolve four models with different masses and angular momenta . we find that in all cases , viscosity drives the cores to rigid rotation and transports angular momentum outwards into the envelope . as a result , the core contracts in a quasi - stationary manner , and the outer layers expand to form a differentially rotating torus . of the four models we have studied , the star with the highest mass collapses to a black hole , with about 20% of the rest mass leftover to form a massive accretion disk . on the contrary , the other three stars do not collapse to black holes , but form star + disk systems , similar to the final state of the rapidly rotating non - hypermassive neutron stars described above . as will be discussed in section [ rad_cooling ] , viscosity generates heat so that the stars do not evolve adiabatically in general . the extra thermal pressure due to viscous heating helps to support the stars . we also consider the limit of rapid cooling , whereby the heat generated by viscosity is immediately removed from the stars . of the three stars which do not collapse to black holes in the no - cooling limit , we found that the one with the lowest angular momentum undergoes catastrophic collapse in the rapid - cooling limit . about 10% of the rest mass is leftover to form an accretion disk in this case . to test the validity of the axisymmetric results , we perform 3d simulations to check for any nonaxisymmetric instabilities . we do not find any unstable nonaxisymmetric modes and the 3d results agree with the axisymmetric results . our results suggest that viscous braking of differential rotation in a hypermassive neutron star can , but does not always , lead to catastrophic collapse . when catastrophic collapse does occur , the remnant is a black hole surrounded by a massive accretion disk . this outcome is very different from that of the collapse of an unstable , rigidly - rotating `` supramassive '' neutron star , in which the whole star collapses to a black hole , leaving only a tiny amount of material to form a disk @xcite . many models for grbs require a massive disk around a rotating black hole to supply energy by neutrino processes @xcite . our results suggest that viscous forces in a hypermassive star could lead to the formation of a massive disk around such a black hole . the structure of this paper is as follows . in section [ setup ] , we derive the relativistic navier - stokes equations containing shear viscosity in a 3 + 1 form suitable for numerical integration , and describe how we evolve them in both axisymmetry and full 3 + 1 dimensions . we then describe in section iii several tests that we perform to check our code . we present the results of our simulations on five selected stars in section iv . finally , we briefly summarize and discuss our conclusions in section v. throughout this paper , latin indices denote spatial components ( 1 - 3 ) and greek indices denote spacetime components ( 0 - 3 ) . we adopt geometrized units , so that @xmath2 . we evolve the 3-metric @xmath3 and the extrinsic curvature @xmath4 using the bssn formulation @xcite . the fundamental variables for bssn evolution are @xmath5\ , \\ \tilde\gamma_{ij } & \equiv & e^{-4\phi}\gamma_{ij}\ , \\ k & \equiv & \gamma^{ij}k_{ij}\ , \\ \tilde a_{ij } & \equiv & e^{-4\phi}(k_{ij } - { 1\over 3}\gamma_{ij}k)\ , \\ \tilde\gamma^i & \equiv & -\tilde\gamma^{ij}{}_{,j}\ .\end{aligned}\ ] ] the evolution and constraint equations for these fields are summarized in @xcite ( hereafter paper i ) . in the presence of matter , these evolution equations contain the following source terms : @xmath6 where @xmath7 is the stress tensor , and @xmath8 is the future - directed unit normal to the time slice . one must impose gauge conditions which specify the lapse @xmath9 and the shift @xmath10 . we use a k - driver lapse and gamma - driver shift , as described in paper i. the numerical implementation of the equations is discussed in paper i , with some improvements to enhance stability described in @xcite . the latter are particularly relevant for the post - collapse version of our code that we implement with black - hole excision . we treat the matter in our neutron stars as an imperfect fluid with a shear viscosity , but no bulk viscosity and no heat conduction . the stress tensor for the fluid is @xmath11 here , @xmath12 , @xmath13 , @xmath14 , and @xmath15 are the rest - mass density , specific internal energy , pressure , and fluid four - velocity , respectively . the quantity @xmath16 is the coefficient of viscosity and is related to the kinematic viscosity @xmath17 by @xmath18 . the shear tensor @xmath19 is defined by @xcite @xmath20 where @xmath21 is the fluid 4-acceleration . we assume a @xmath22-law equation of state @xmath23 our fundamental fluid variables are @xmath24 where @xmath25 is the specific enthalpy . the conservation of stress - energy @xmath26 and the law of baryon number conservation @xmath27 give the relativistic continuity , energy , and navier - stokes equations @xmath28 where @xmath29 is the 3-velocity . the quantity @xmath30 is determined by the normalization condition @xmath31 , which yields @xmath32^{-2}\ , \ ] ] where @xmath33 . the stress - tensor @xmath34 generates the following source terms in the field evolution equations : @xmath35 many of the systems we evolve possess and maintain symmetry about their rotation axis , which we set to be the @xmath36-axis . then we can eliminate one dimension and simplify the equations . we utilize axisymmetry and follow @xcite to evolve the field and hydrodynamic variables on the @xmath37 plane . the data off of this plane can be obtained by rotating the data on this plane . as we explain in section [ axisym_methods ] , we find it advantageous when performing 2 + 1 simulations to evolve the hydrodynamic equations ( [ evolve_rhostar])-([evolve_stilde ] ) in cylindrical coordinates but on a cartesian ( @xmath38 ) grid . on the @xmath37 plane , the cylindrical coordinates @xmath39 , @xmath36 , and @xmath40 are related to the cartesian coordinates @xmath41 , @xmath42 , and @xmath36 as follows : @xmath43 , @xmath44 , @xmath45 . using these relations , eqs . ( [ evolve_rhostar])-([evolve_stilde ] ) in cylindrical coordinates can be written @xmath46 \nonumber\\ & & \partial_t ( \tilde s_y - 2\alpha e^{6\phi}\eta\sigma^0_y ) \label{eulery}\\ & & \qquad\ \ + { 1 \over x^2}\partial_b(x^2 \tilde s_y v^b - 2\alpha e^{6\phi}\eta x^2 \sigma^a_y)=0 \nonumber \\ & & \partial_t e_{\star } + { 1 \over x}\partial_b(e_{\star } x v^b ) \label{energy } \\ & & \qquad\ \ = { 2\over\gamma } \alpha e^{6\phi}\eta ( \rho_0\epsilon)^{(1-\gamma)/\gamma}\sigma^{\alpha\beta}\sigma_{\alpha\beta } \ , \nonumber\end{aligned}\ ] ] where the indices @xmath47 and @xmath48 run over @xmath41 and @xmath36 ( c.f . eq.(2.10)-(2.13 ) of @xcite ) . there are two dynamical timescales for a rotating star . gravity provides the free - fall timescale @xmath49 @xmath50 where @xmath0 is the gravitational mass of the star ( or merged binary remnant ) and @xmath51 is the radius . if the star is rotating , its rotation period @xmath52 provides another important timescale : @xmath53 dynamical instabilities ( e.g. instability to radial collapse or to dynamical bar formation ) will act on the above timescales . the stars we study are dynamically stable initially , so their structure is altered on secular timescales . rotating compact stars may be secularly unstable to gravitational - radiation driven instabilities . the strongest instabilities of this kind are the ( nonaxisymmetric ) @xmath1-modes and the bar mode . the timescale of the @xmath54 @xmath1-mode instability is given by @xcite @xmath55 the gravitational - radiation driven ( dedekind ) bar - mode instability occurs if the star is rapidly rotating so that @xmath56 , where @xmath57 is the ratio of kinetic to gravitational potential energy . the threshold @xmath58 for a newtonian star ( @xmath59 ) , and _ decreases _ as the compactness of the star ( i.e. @xmath60 ) increases @xcite . the timescale of this instability is estimated to be @xcite @xmath61 viscosity alone can also drive a ( jacobi ) bar - mode instability . the threshold is identical for a newtonian star ( @xmath58 ) but _ increases _ as the compaction increases @xcite . the relevant timescale is ( see @xcite , p.99 ) @xmath62 this is comparable to the viscous timescale @xmath63 discussed below . magnetic fields coupled to the matter will redistribute angular momentum . in fact , even an initially small magnetic field frozen into the matter will be wound up and can destroy differential rotation in the star on an alfvn timescale @xcite : @xmath64 viscosity will also redistribute angular momentum on a viscous timescale @xmath65 . one form of viscosity present in neutron stars is due to the transport of energy and momentum of neutrons . this viscosity acts on a timescale @xcite @xmath66 where @xmath67 , and @xmath68 is the characteristic temperature . it is widely believed that , for cold neutron stars ( @xmath69 ) , the neutron fluid in the inner crust condenses into a superfluid of @xmath70 cooper pairs @xcite , while in the interior , the neutrons could form a @xmath71 superfluid @xcite ( although this is less certain ) , and the protons a @xmath70 superfluid . in the case of neutron superfluidity , @xmath72 will vanish , and the dominant viscosity will be due to electron - electron scattering @xcite @xmath73 electron and proton fluids are forced to move together in the mhd limit @xcite . differences in velocity between the neutron and proton - electron fluids are damped fairly quickly by mutual friction @xcite . viscosity can be used as a model for turbulence in certain situations . turbulence may occur in young neutron stars as a result of pure hydrodynamic effects or magnetic instabilities @xcite . turbulence is often modeled by the `` @xmath9-disk '' law , in which a shear stress @xmath74 is added to the hydrodynamic equation ( see e.g. @xcite , chap . 14 ) . here @xmath9 is a nondimensional constant ( which should not be confused with the lapse function ) with values in the range @xmath75 . the viscosity in this model roughly corresponds to @xmath76 , where @xmath77 is the velocity of turbulent cells relative to the mean fluid motion , @xmath78 is the size of the largest turbulent cell , and @xmath79 is the sound speed . the corresponding timescale is @xmath80 which is much shorter than all the other secular timescales . hence turbulent viscosity , if present , is likely to dominate the secular evolution of differentially rotating stars . thermal energy is radiated away primarily by neutrinos . for hot neutron stars ( @xmath81 ) , the cooling is dominated by the direct urca process , and the star cools on a timescale @xmath82 s ( see @xcite and @xcite , chap . 11 ) . for cooler neutron stars , the cooling is dominated by the modified urca process , and the star cools on a timescale @xmath83 s @xcite . depending on the temperature and the nature of the viscosity , the cooling timescale may be greater than or less than the viscous timescale . if @xmath84 , then the heat generated by viscosity will build up inside the star . otherwise , it will be radiated away as quickly as it is generated . we study both limits in this paper . secular effects will in general take many rotation periods to significantly affect the structure or velocity profile of a differentially rotating star . this poses a challenge to the numerical treatment of these changes . because of the short courant timestep required for numerical stability , it would be computationally prohibitive to evolve a star for such a long time using an explicit finite differencing scheme . the use of a fully implicit scheme for the finite differencing can allow stable evolutions with larger @xmath85 . each timestep is , however , much more computationally expensive as it involves matrix inversion . moreover , no fully implicit routine for the coupled einstein field and relativistic hydrodynamic equations exists at present . the secular timescales are so much longer than the dynamical timescales that the star can be thought of as evolving quasi - statically . therefore , it might be possible to treat the secular evolution in the quasistatic approximation , as in typical stellar evolution ( henyey ) codes , by constructing a sequence of equilibrium configurations up to the moment that stable equilibrium can no longer be sustained . this approach has been used to study the viscous evolution of differentially rotating white dwarfs @xcite . however , building the required equilibrium models in full general relativity is a nontrivial task . it would be particularly difficult to identify the meridional currents and core - halo bifurcation that often arise in rapidly rotating configurations . more significantly , it would not be possible to follow the evolution of the configuration with a quasistationary approach if a dynamical instability ( i.e. collapse ) is triggered during the secular evolution . instead , we use our relativistic hydrodynamic code and artificially amplify the strength of viscosity so that the viscous timescale is short enough to make numerical treatment tractable . however , we keep the viscous timescale sufficiently long that the hierarchy of timescales is maintained , and the secular evolution still proceeds in a quasi - stationary manner . the behavior of the real system can then be determined by rescaling the time variable to adjust the viscous timescale to its physical value . the characteristic viscous timescale is @xmath86 where @xmath87 is an averaged value of @xmath16 across the star . suppose we evolve the same star , once with @xmath88 and once with @xmath89 . if both @xmath90 and @xmath91 are large enough so that they do not compete with the dynamical timescale , but shorter than any other secular timescale ( see , e.g. section [ timescales ] ) , then the configuration of the star with viscosity @xmath90 at time @xmath92 will be the same as the configuration of the star with viscosity @xmath91 at time @xmath93 . by varying @xmath65 over a wide range and corroborating this scaling , we are confident that the physical behavior we observe is real . we can then scale the result of numerical simulations to the appropriate strength of viscosity , provided that the physically relevant viscous timescale is much shorter than all the other secular timescales ( e.g. , @xmath94 , @xmath95 ) . as discussed in the previous subsection , turbulent viscosity is likely to dominate the secular evolution . we adopt the stress tensor as in eq . ( [ tuv ] ) and specify the viscosity @xmath16 suitable for modeling turbulence . we consider the turbulent viscosity described in @xcite : @xmath96 ( this viscosity law is also used in some accretion - disk models @xcite . ) typically , @xmath77 is proportional to the sound speed @xmath79 . hence @xmath97 . for simplicity , we assume that @xmath98 is constant inside the star . then we have @xmath99 where @xmath100 is a constant , and is related to the coefficient of kinematic viscosity @xmath17 by @xmath101 . in our numerical simulations we specify the value of @xmath102 for each run . we model the initial stars as rotating polytropes with polytropic index @xmath103 , so that @xmath104 . it is convenient to rescale all quantities with respect to @xmath105 . since @xmath106 has dimensions of length , we can define the following nondimensional variables @xcite @xmath107 where the spacetime coordinates are @xmath108 . however , to simplify our notation , we will drop all the bars . hereafter , all variables are understood to be in `` @xmath109 units . '' using eq . ( [ tvis_general ] ) , we can see that @xmath65 scales with @xmath51 , @xmath110 , and @xmath102 as @xmath111 which for @xmath112 becomes @xmath113 for definiteness , we take @xmath65 to be @xmath114 where @xmath115 is the equatorial radius , @xmath116 is the maximum value of @xmath12 in the star , and @xmath117 is a dimensionless constant . we use the constant @xmath117 to approximately match @xmath65 to the rate of decay of differential rotation observed by our simulations . with the appropriate @xmath65 , the value of @xmath118 , which is proportional to the rate of energy dissipation [ see eq . ( [ evolve_estar ] ) ] , is expected to decay like @xmath119 we measure @xmath65 by numerically evolving a given star , and observing the decay with time of @xmath120 , the average value of @xmath121 throughout the star , weighted by rest density . we determine the value of @xmath117 by requiring that @xmath65 roughly corresponds to the e - folding time of the decay of @xmath122 . carrying out this measurement on a sampling of the stars used below , we find that @xmath123 in all cases . thus we use @xmath124 to define @xmath65 in the sections below . we note that the turbulent viscosity adopted above for our numerical treatment is roughly equivalent to an `` @xmath9 '' model provided we identify @xmath125 . ( [ tvis_p ] ) for @xmath65 is then equivalent to eq . ( [ t_turb ] ) . our stars do not evolve isentropically . viscosity heats the matter on a timescale @xmath65 , as shown by eq . ( [ evolve_estar ] ) . at the same time , neutrino radiation carries away heat , cooling the star on a timescale @xmath126 . we will carry out simulations below in two opposite limits , which we describe in some detail in appendix [ cooling_app ] . in the _ no - cooling _ limit , @xmath127 , so we ignore radiative cooling and simply evolve eqs . ( [ evolve_rhostar])-([evolve_stilde ] ) . in the _ rapid - cooling _ limit , @xmath128 , so we evolve eqs . ( [ evolve_rhostar])-([evolve_stilde ] ) as before , but _ without including _ the viscous heating term in the energy equation [ eq . ( [ evolve_estar ] ) ] . this will allow net heating by adiabatic compression but not by viscosity . the viscous heat is assumed to be ( instantaneously ) lost by radiation in this limit , while viscous braking proceeds . the emitted radiation will carry off some momentum as well as energy , causing a modification of eq . ( [ evolve_stilde ] ) , but this will have a much smaller effect provided the luminosity does not exceed the ( neutrino ) eddington luminosity . baumgarte and shapiro @xcite investigated the loss of angular momentum in binary neutron star merger remnants due to radiation , and they found it to be fairly small . we therefore feel justified in ignoring radiative corrections to eq . ( [ evolve_stilde ] ) . our hydrodynamical scheme employs van leer - type advection with artificial viscosity to handle shocks . we also use a `` no - atmosphere '' approach , in which the density at any point on our grid can fall exactly to zero . our hydrodynamical algorithms are described in detail in paper i. we have evolved the above equations both in two dimensions , assuming axisymmetry , and in three dimensions . using axisymmetry saves us computational time and allows us to use higher resolution . however , 3d runs must still be carried out for rapidly rotating systems in order to check for the occurrence of nonaxisymmetric instabilities . there are several ways to evolve in axisymmetry . one could write the field and hydrodynamic evolution equations in cylindrical coordinates ( @xmath129,@xmath36,@xmath130 ) and evolve in this coordinate system . this has the advantage that one can explicitly remove the dependence of the variables on @xmath130 . unfortunately , there are singularities in the cylindrical coordinate system which can make the evolution of the field equations in these coordinates difficult . instead , we choose to evolve the metric variables ( @xmath131 , @xmath132 , @xmath133 , @xmath134 , @xmath135 , @xmath9 , and @xmath10 ) in axisymmetry using the cartoon method @xcite . in this approach , variables are evolved on a cartesian grid consisting of three planes corresponding to @xmath136 , @xmath137 , and @xmath138 . then the middle ( @xmath137 ) plane is evolved using the 3d evolution equations in cartesian coordinates . each time the middle plane is evolved forward one timestep , the @xmath136 and @xmath138 planes are updated by applying the assumption of axisymmetry . thus , the value of a tensor * f * at location @xmath139 on @xmath140 is equal to * f * at @xmath141 rotated by ( coordinate ) tensor transformation about the @xmath36-axis by angles @xmath142 . since an arbitrary point @xmath141 will generally not coincide with any gridpoint on the @xmath37 plane , interpolation in @xmath41 is necessary to apply this update . we use third - order polynomial interpolation , so that we do not lose second - order accuracy . with the hydrodynamic evolution equations , we also have the choice of either evolving in cylindrical coordinates or evolving in cartesian coordinates using the cartoon prescription . like shibata in his work on axisymmetric star collapse @xcite , we choose to evolve the fluid variables in cylindrical coordinates , i.e. we use eqs . ( [ continuity])-([energy ] ) . this is superior to using the cartoon method because eq . ( [ continuity ] ) can be finite differenced in such a way that the total rest mass will be exactly conserved ( except for flow beyond the outer boundaries ) . in the absence of viscosity , angular momentum also becomes a numerically conserved quantity . we have found that evolving the fluid variables in cylindrical coordinates gives significantly more accurate runs than evolving via cartoon hydrodynamics . the drawback of using 2d evolutions is the instability caused by the coordinate singularity on the @xmath143 axis . ( this instability is also present if we use the 3d cartesian navier - stokes equations together with the cartoon boundary condition . ) there are several ways of removing this instability . shibata @xcite adds a small artificial shear viscosity @xmath144 where @xmath145 is the flat - space laplacian , and @xmath146 is the momentum variable evolved by the code of @xcite ( instead of @xmath147 ) . we have confirmed that adding such a term to eq . ( [ evolve_stilde ] ) can stabilize our code . however , since we will be studying the effects of real shear viscosity , we instead choose to remove the instability using a higher - order dissipation scheme . namely , we add a small kreiss - oliger dissipation term @xcite @xmath148 we use @xmath149 for all the simulations reported in this paper . in both 2d and 3d simulations , we assume that our system preserves equatorial symmetry across the @xmath150 plane , and we therefore only evolve the @xmath151 portion of the grid . in 3d runs , we make the added assumption of @xmath152-symmetry , which allows us to evolve only half of the remaining grid , which we choose to be the @xmath153 half . when performing 2d runs , we evolve only the region @xmath154 since the values of variables in the @xmath155 region can be deduced from the values on the @xmath154 region from the assumed axisymmetry . we compute all spacial derivatives using standard centered differencing . we integrate forward in time using a 3-step iterated crank - nicholson scheme . so , for example , we evolve the equation @xmath156 from timestep @xmath157 at time @xmath92 to timestep @xmath158 at time @xmath159 by the following algorithm : + ` ( i ) predict : { } ^1f^{n+1 } \equiv f^n + \delta t \dot f(f^n ) ` + ` ( ii ) 1st correct : ~ { } ^2f^{n+1 } \equiv f^n + \delta t [ 0.4\dot f(f^n)+0.6\dot f({}^1f^{n+1 } ) ] ` + ` ( iii ) 2nd correct : ~ f^{n+1 } = f^n + \delta t [ 0.4\dot f(f^n)+0.6\dot f({}^2f^{n+1 } ) ] ` + as discussed in paper i , the coefficients 0.4 and 0.6 were chosen to improve stability . in the presence of viscosity , the time - differencing is not entirely straightforward , due to the presence of time derivatives of @xmath15 in @xmath19 , and of time derivatives of @xmath19 in the navier - stokes equations . thus , @xmath160 ( which gives @xmath161 ) is an expression which itself contains @xmath161 and @xmath162 . since the viscosity is a small perturbing force on the fluid motion , we find that it is sufficient to split off the viscous terms and integrate them separately ( operator splitting ) . in particular , we compute @xmath161 and @xmath163 appearing in the viscous terms in a non - time centered way . consider the @xmath164 evolution equation for the viscous piece : @xmath165 , where we have suppressed all indices . to evolve this equation from timestep @xmath157 to timestep @xmath166 , we need to know the time derivatives of @xmath167 and @xmath168 . when performing the predictor step , these time derivatives are approximated by subtracting values of the fields on the timestep @xmath157 from those on the previous timestep , @xmath169 . + ` ( i ) before predictor step , ~ compute \dot u^{n-1/2 } = [ u^n - u^{n-1}]/\delta t , ~ \sigma^n = \sigma(u^n,\dot u^{n-1/2 } ) , ~ \dot \sigma^{n-1/2 } = [ \sigma^n - \sigma^{n-1}]/\delta t ` + note that these time derivatives are centered at @xmath170 . we then carry out the predictor step . + ` ( ii ) predict : { } ^1\tilde s^{n+1 } = \tilde s^n + \delta t \dot{\tilde s}(\sigma^n,\dot\sigma^{n-1/2 } ) ` + from the predicted values of @xmath167 and @xmath168 , we construct time derivatives centered at @xmath171 and use these in the corrector step . + ` ( iii ) compute { } ^1u^{n+1 } from { } ^1\tilde s^{n+1 } ~ { } ^1\dot u^{n+1/2 } = [ { } ^1u^{n+1 } - u^{n}]/\delta t , ~ { } ^1\sigma^{n+1 } = \sigma({}^1u^{n+1},{}^1\dot u^{n+1/2 } ) , ~ { } ^1\dot \sigma^{n+1/2 } = [ { } ^1\sigma^{n+1 } - \sigma^{n}]/\delta t ` + ` ( iv ) 1st correct : ~ { } ^2\tilde s^{n+1 } = \tilde s^n + \delta t[0.4\dot{\tilde s}(\sigma^n,\dot\sigma^{n-1/2 } ) ~ + 0.6\dot{\tilde s}({}^1\sigma^{n+1},{}^1\dot\sigma^{n+1/2 } ) ] ` + ` ( iii ) compute { } ^2u^{n+1 } from { } ^2\tilde s^{n+1 } ~ { } ^2\dot u^{n+1/2 } = [ { } ^2u^{n+1 } - u^{n}]/\delta t , ~ { } ^2\sigma^{n+1 } = \sigma({}^2u^{n+1},{}^2\dot u^{n+1/2 } ) , ~ { } ^2\dot \sigma^{n+1/2 } = [ { } ^2\sigma^{n+1 } - \sigma^{n}]/\delta t ` + ` ( iv ) 2nd correct : ~ \tilde s^{n+1 } = \tilde s^n + \delta t[0.4\dot{\tilde s}(\sigma^n,\dot\sigma^{n-1/2 } ) ~ + 0.6\dot{\tilde s}({}^2\sigma^{n+1},{}^2\dot\sigma^{n+1/2 } ) ] ` by differencing the equations in this way , the dominant nonviscous terms in the evolution equations are accurate to second order ( except for small effects due to the use of the coefficients 0.4 and 0.6 in the corrector steps ) , but small viscous terms involving time derivatives are only accurate to first order in @xmath85 . numerical convergence tests show that our code is nearly second - order convergent in space and time . we find this to be sufficient for our purposes . when computing @xmath19 , we first use eq . ( [ sigma_def ] ) to get the spatial components @xmath172 . the remaining components @xmath173 are then obtained from the conditions @xmath174 . as in most other eulerian hydrodynamic codes , high velocities can easily develop in the low - density regions near the surfaces of our stars . the method for evolving such regions in the absence of viscosity is described in paper i. since calculation of the shear tensor involves taking derivatives of the velocity field , we are unable to calculate it accurately in the very low - density regions . to ensure stability , we set @xmath175 in regions where @xmath176 . since these low - density regions contain an insignificant amount of rest mass , this prescription should not affect our evolutions . we confirm this by varying the cutoff density in several test problems and checking that the effect is negligible . our most important diagnostics are the total mass - energy @xmath0 and angular momentum @xmath177 . these are both defined by surface integrals at infinity @xcite : @xmath178 using gauss law , these surface integrals can be converted to volume integrals : @xmath179 in axisymmetry , the angular momentum integral simplifies to @xcite @xmath180 henceforth , we drop the subscript @xmath36 since all angular momentum is in the @xmath36-direction . the mass @xmath0 and angular momentum @xmath177 in our grid should be strictly conserved only in the absence of radiation ( although gravitational radiation carries no angular momentum in axisymmetry ) . since the energy and angular momentum emitted in gravitational waves are negligible in our runs , this means that @xmath0 and @xmath177 should be conserved in the no - cooling limit . they thus serve as useful code checks in this limit . in the rapid - cooling limit , the mass computed by the volume integral ( [ mfin ] ) over the numerical grid will not be conserved thermal energy is carried off of the grid by thermal radiation . the expected rate of mass - energy decrease due to thermal energy loss can be computed by differentiating eq . ( [ mfin ] ) with respect to time . to lowest order , we can ignore the effects of the quasi - stationary loss of thermal energy on the spacetime , and so ignore the time derivatives of field variables . then only the first term in eq . ( [ mfin ] ) will be important . @xmath181 where @xmath182 is the component of the time derivative of @xmath110 caused by loss of internal energy due to cooling . this quantity may be computed by applying the chain rule to eq . ( [ rho_source ] ) : @xmath183 changes in @xmath30 are ignored because they represent a higher - order influence on @xmath184 . the rate of change in @xmath185 due to cooling is given by the effective balance of heating and cooling that characterizes the rapid - cooling limit ( see appendix a ) . thus , @xmath186 is minus the value of @xmath187 due to viscous heating , i.e. @xmath188 [ see eq . ( [ evolve_estar ] ) ] . from equations ( [ chain ] ) and ( [ e_cool ] ) , it is straightforward to construct @xmath189\ .\end{aligned}\ ] ] finally , the quantity which is nearly conserved in the rapid - cooling limit ( up to losses due to gravitational radiation ) is @xmath190 in both the no - cooling and rapid - cooling runs , we can divide @xmath0 into its constituent pieces : the rest mass @xmath191 , internal energy mass @xmath192 , kinetic energy @xmath68 , and gravitational potential energy @xmath193 , defined by @xcite @xmath194 where @xmath195 is the proper 3-volume element . to study the effects of heating , it is useful to break up the internal energy @xmath13 into its `` cold '' component @xmath196 , and its `` thermal '' component @xmath197 . then we can break up @xmath192 into cold and hot components @xmath198 note that in the rapid - cooling limit , @xmath199 . finally , we also compute the circulation along closed curves . for a closed curve @xmath200 with tangent vector @xmath201 , the circulation is defined to be @xmath202 where @xmath203 parameterizes points on @xmath200 [ i.e. @xmath204 . according to the kelvin - helmholtz theorem , the circulation @xmath205 will be conserved in the absence of viscosity if @xmath200 moves with the fluid and if the fluid is barotropic [ @xmath206 . when viscosity is present or the equation of state is more general , as in the case of nonisentropic flow , the navier - stokes equations give @xmath207 d\zeta\ . \label{evolve_circ}\ ] ] if @xmath175 , the second term in the integrand vanishes , and if @xmath208 , the remaining term is an exact differential . then @xmath209 integrates to zero , in accord with the kelvin - helmoltz theorem . in axisymmetry , we choose to evaluate @xmath205 on circular rings on the equatorial @xmath150 plane , so that @xmath210 . the ring @xmath200 intersects our 2d grid at a point on the @xmath41-axis . by our symmetries , the curve @xmath200 will always remain circular and always remain at @xmath150 , so the lagrangian point representing @xmath200 only moves in @xmath41 . evolution in @xmath92 and in @xmath211 are simply related by @xmath212 . since the system is axisymmetric , the integrand , being a scalar , is constant along @xmath200 , so eqs . ( [ circ_define ] ) and ( [ evolve_circ ] ) simplify to @xmath213 \label{circ_fin}\ .\end{aligned}\ ] ] hence the quantity @xmath214 given by @xmath215 is conserved , even in the presence of viscosity . finally , we compute the hamiltonian and momentum constraint violations [ given by equations ( 16 ) and ( 17 ) of paper i ] . we monitor the l2 norm of the violation of each constraint . we compute the l2 norm of a gridfunction @xmath216 by summing over every gridpoint @xmath217 : @xmath218 the constraint violations are normalized as described in paper i [ eqs . ( 59 ) and ( 60 ) ] . 0.07 in [ cols="^,^,^,^,^,^,^,^,^",options="header " , ] @xmath219 the time at which the simulation was terminated . + @xmath220 this quantity corresponds to an average of @xmath221 over the final configuration of the star weighted by rest - mass density at the end of the simulation . thermal pressure generated by viscous heating causes @xmath222 ( recall @xmath223 ) . we find that the viscous heating is much more significant in the low - density region than in the core . + @xmath224 these values are obtained by solving eqs . ( [ eq : jisco])([eq : q ] ) . + @xmath225 the quantity @xmath57 is undefined when the star undergoes a dynamical collapse . the number given here is an approximate value before the star becomes dynamically unstable . [ tab : results ] four of the five stars we consider are hypermassive , and we expect viscosity to change their structure significantly . star i is the most hypermassive star ( @xmath226 , where @xmath227 is the mass limit for uniformly rotating @xmath112 polytropes , i.e. for stars at the mass - shedding limit @xcite ) . we find that this star eventually collapses to a black hole , but a substantial amount of rest mass is leftover to form a massive accretion disk . we consider three other hypermassive models ( stars ii , iii and iv ) to study whether or not all hypermassive neutron stars will collapse in the presence of viscosity . stars ii , iii and iv have the same rest mass ( @xmath228 ) which is slightly smaller than that of star i but different angular momenta @xmath177 . we find that stars iii and iv never collapse , but evolve in a quasi - stationary manner to a uniformly rotating core surrounded by a low - density , disk - like envelope . star ii eventually collapses to a black hole if we impose rapid cooling . in the no - cooling limit , however , this model forms a uniformly rotating core surrounded by a substantial disk . star v is the only non - hypermassive model . as expected , this star does not collapse under the action of viscosity . however , viscosity can not drive the whole star to rigid rotation , because the angular momentum of the star exceeds the maximum angular momentum allowable for a rigidly - rotating star having the same rest mass . instead , viscosity again leads to a uniformly rotating core and a differentially rotating disk - like envelope . the final outcomes of the five models are summarized in table [ tab : results ] . we also performed 3d simulations on stars i and iv to search for unstable , nonaxisymmetric secular modes . a nonaxisymmetric bar instability usually develops when a star is rotating rapidly , i.e. has a sufficiently large @xmath57 . of the five models we study , stars i and iv have the highest @xmath57 . we do not find any nonaxisymmetric instabilities in these two models , and the 3d results roughly agree with the axisymmetric results . we discuss the results of our simulations in detail in the following subsections . 0.5 cm star i is the most massive neutron star we study . we first perform an axisymmetric calculation with no cooling . at @xmath229 , the star has a toroidal density profile , i.e. , the maximum density occurs off center ( see the upper left panel of fig . [ fig : conti ] ) . as viscosity gradually brakes differential rotation , the star readjusts to a monotonic density profile . figure [ fig : rho_alpha_i ] shows the maximum rest - mass density and the minimum value of the lapse as a function of time . figure [ fig : conti ] shows the meridional rest - mass density contours at various times . we see that a meridional current is built up in the process . however , the magnitude of the meridional velocity ( @xmath230 ) is much smaller than the typical rotational velocity ( @xmath231 ) . and the rest mass of the disk @xmath232 after the appearance of the apparent horizon at @xmath233 . note that time is plotted in units of @xmath0 ( @xmath234 ) . black hole excision is employed to track this late evolution.,width=302 ] viscosity destroys differential rotation and transfers angular momentum to the outer layers . in the early phase of the evolution , the core contracts and the outer layers expand in a quasi - stationary manner . as the core becomes more and more rigidly - rotating , it approaches instability because the star is hypermassive and can not support a massive rigidly - rotating core . at time @xmath235 , the star becomes dynamically unstable and collapses . an apparent horizon appears at time @xmath236 . without black hole excision , the code crashes about @xmath237 after the horizon appears because of grid stretching . about 30% of rest mass remains outside the apparent horizon at this point . we then continue the evolution using the excision technique described in @xcite . we are able to extend the evolution reliably for another @xmath238 . the system settles down to a black hole surrounded by a massive ambient disk . the rest mass @xmath232 and angular momentum @xmath239 of the disk can be calculated by integrating the rest - mass and angular momentum density over the volume outside the apparent horizon [ c.f . ( [ def : m_0 ] ) and ( [ jaxi ] ) ] . the mass of the black hole can be estimated by the proper circumference of the horizon in the equatorial plane : @xmath240 ( assuming that the spacetime can be described by a kerr metric ) . figure [ fig : excision ] shows the evolution of @xmath241 and the rest mass of the disk @xmath232 . we estimate the final values of @xmath241 , @xmath232 , and @xmath239 by fitting these curves to analytic functions of the form @xmath242 and extrapolating these fitting functions to @xmath243 @xcite . we estimate that the mass of the final black hole is @xmath244 . the asymptotic rest mass and angular momentum of the ambient disk are found to be @xmath245 and @xmath246 . we can infer from the conservation of angular momentum that the final angular momentum of the black hole is @xmath247 . hence we find @xmath248 . the formation of a massive disk is mainly due to the fact that viscosity transports angular momentum from the inner core to the outer layers . the material in the outer region is unable to fall into the black hole because of the centrifugal barrier . the final mass of the black hole and disk can also be estimated independently from the conservation of specific angular momentum using a method developed by shapiro and shibata @xcite , which we apply below . during the dynamical collapse , the effect of viscosity is negligible . since the spacetime is axisymmetric , the specific angular momentum @xmath249 of a fluid particle is conserved . for a kerr black hole of mass @xmath241 and angular momentum @xmath250 , the specific angular momentum of a particle at the innermost stable circular orbit ( isco ) @xmath251 is given by @xmath252 where @xmath253 . the isco radius is @xmath254 \ , \ ] ] where @xmath255 \ \ ] ] and @xmath256 the rest mass and angular momentum of the escaping matter in the envelope with @xmath257 is given by @xmath258 we assume that the energy radiated by gravitational waves is negligible so that the total mass - energy of the system is approximately conserved . hence we have m & = & m_h + m_disk , [ eq : meq ] + j & = & j_h + j_disk . [ eq : jeq ] for a bound system , the contribution to the mass - energy of the matter in the disk , @xmath259 , is smaller than its rest mass @xmath260 . we write @xmath261 we consider two opposite limits for @xmath262 : @xmath263 and @xmath264 . the value @xmath265 is a good approximation in the weak gravity regime . in the limit where @xmath266 , we have @xmath267 and @xmath268 . hence in this limit , @xmath269 , which is 0.92 for star i ( see table [ tab : models ] ) . we expect that the correct @xmath262 lies somewhere between these two extremes , which are not very different . the mass and angular momentum of the black hole can be estimated by solving the system of transcendental eqs . ( [ eq : jisco])([eq : q ] ) at a particular time slice during the pre - excision dynamical collapse phase , including the time slice at the onset of dynamical collapse ( where @xmath262 is close to unity ) . we find that the values of @xmath241 and @xmath250 are insensitive to @xmath262 . they are also insensitive to which time slice we choose to do the calculation . we find @xmath270 and @xmath271 ( @xmath272 ) . the rest mass in the ambient disk is found to be @xmath273 . it should be noted that this calculation is based on the assumptions that the spacetime around the disk can be approximated by a kerr metric , and that the disk is moderately thin and lies in the equatorial plane of the hole . this approximation is not reliable when the disk is massive ( @xmath274 ) . in our case , we find this calculation agrees rather well with the actual asymptotic values determined by the dynamical simulation with excision . henceforth we will use eqs . ( [ eq : jisco])([eq : q ] ) to estimate @xmath241 , @xmath250 , @xmath232 and @xmath239 whenever an apparent horizon forms . 0.5 cm since viscosity is small in the low - density region , it takes longer to remove the differential rotation in the outer layers . figure [ fig : omegai ] shows the angular velocity profiles at various times . we see that by the time the inner core collapses , the material in the outer layers is still differentially rotating . after the dynamical collapse , viscosity will cause some of the remaining material to slowly accrete onto the black hole . we monitor the conserved quantities and the constraints during the entire evolution . since our finite - difference scheme preserves the rest mass , the variation of @xmath191 can only come from material flowing out of the grid . we find that @xmath191 is conserved to 0.01% , and angular momentum is conserved to 0.1% . the hamiltonian constraint is violated by less than 0.3% before the dynamical collapse occurs . it increases to 3% by the time an apparent horizon appears . the momentum constraints are violated by less than 1% before the dynamical collapse occurs , and increase to 6% by the time an apparent horizon appears . 0.5 cm we next perform an axisymmetric simulation of star i with rapid cooling . the dashed lines in fig . [ fig : rho_alpha_i ] show the time evolution of the maximum rest - mass density and the minimum value of the lapse . as in the no - cooling case , the inner core contracts and the outer layers expand in a quasi - stationary manner . the core then collapses dynamically to a black hole and leaves behind a massive accretion disk . since there is no viscous heating , the whole process occurs more quickly than in the no - cooling case . the dynamical collapse occurs at time @xmath275 and the apparent horizon appears at @xmath276 . figure [ fig : conti_cool ] shows the meridional rest - mass density contours at various times . we estimate , by solving eqs . ( [ eq : jisco])([eq : q ] ) at @xmath277 with @xmath263 , that the mass and angular momentum of the final black hole are @xmath270 and @xmath278 ( @xmath279 ) . about 20% of rest mass escapes capture to form an accretion disk . ] so that the curves again coincide , which indicates that viscosity plays an insignificant role during the dynamical collapse phase.,title="fig:",width=302 ] 0.5 cm in section [ visctest ] , we demonstrated that when the viscous timescale is significantly longer than the dynamical timescale , the secular rates of change of all physical quantities scale inversely with viscosity . the secular evolution of star i with rapid cooling is short enough for us to perform another detailed scaling test . figure [ fig : scaling ] demonstrates this scaling behavior by evolving star i with four different strengths of viscosity @xmath280 0.4 , 0.2 , 0.1 , and 0.05 . ( the curves in fig . [ fig : rho_alpha_i ] correspond to @xmath281 . ) we see that the scaling holds until dynamical collapse at time @xmath282 . when @xmath283 , the evolution of the system is no longer driven by viscosity . we therefore expect that the collapse is independent of the strength of viscosity as long as the viscous timescale is much longer than the dynamical timescale . in the lower panel of fig . [ fig : scaling ] , we demonstrate that it is possible to shift the time axes ( @xmath284 ) so that the four viscosity runs yield the same result when @xmath285 , which indicates that viscosity is insignificant during the dynamical collapse . the values of @xmath286 are determined by requiring that the scaling relation @xmath287 holds , and that the four curves be aligned when plotted against the shifted time @xmath288 . we found that @xmath289 6.1 , 12.0 , 24.08 and 47.75 respectively for @xmath280 0.4 , 0.2 , 0.1 , and 0.05 . the fact that we are able to find @xmath290 that satisfies these requirements validates our physical interpretation of the two phases of evolution . of the particles at time @xmath229 is chosen so that the initial fraction of rest mass @xmath291 interior to the cylinder of radius @xmath292 is , from left to right , @xmath293=0.03 , 0.1 , 0.2 , 0.3 , 0.4 , 0.5 , 0.6 , 0.7 , 0.8 and 0.9 . the cross in the diagram denotes the location of the apparent horizon at the end of the simulation.,title="fig:",width=302 ] 0.5 cm to better visualize the effects of viscosity , we follow the motions of ten selected lagrangian fluid elements . figure [ fig : worldlines ] shows the worldlines of these particles . we choose the particles to be in the equatorial plane of the star . equatorial symmetry implies that the particles will remain in the equatorial plane at all times . the position of a fluid particle @xmath292 satisfies the equations @xmath294 we label the particles by the initial fraction of rest mass interior to the cylinder of radius @xmath292 . we see that the particles with the initial mass fraction @xmath295 move toward the center and ultimately move inside the apparent horizon , while those with @xmath296 move away from the center and remain outside the apparent horizon . this agrees with our estimates of the rest mass of the ambient disk . of star i in the rapid - cooling limit . the mass is not conserved since the thermal energy generated by viscous heating is removed . however , the sum of the remaining mass and the mass carried away by `` radiation '' , @xmath297 , is approximated conserved.,title="fig:",width=302 ] 0.5 cm since there is rapid cooling , the mass is not conserved because the thermal energy generated by viscous heating is removed , as discussed in section [ diagnostics ] . however , when we account for the mass - energy carried away by thermal radiation , @xmath297 , the total mass @xmath298 should be conserved approximately [ see eq . ( [ mtot ] ) ] . figure [ fig : mi ] shows @xmath0 and @xmath299 as a function of time before an apparent horizon appears . the total mass is well - conserved except near the end of the simulation , where the numerical error arising from the grid stretching causes a few percent drop in the mass . we monitored the violations of the constraints during the evolution . the violation of the hamiltonian constraint is @xmath300 before the dynamical collapse occurs , and goes up to 7% at the time when the apparent horizon appears . the violations of the momentum constraints are also before the dynamical collapse occurs , and increase to 8% at the time when the apparent horizon appears . 1.0 cm 0.5 cm the evolution of star ii due to viscosity is different from that of star i. although it is still hypermassive , the mass of star ii is smaller than that of star i. when evolved in the absence of cooling , the star does not collapse to a black hole , but forms a rigidly - rotating core with a low - density disk - like envelope . when evolved in the rapid - cooling limit , however , the star collapses to a black hole . figure [ fig : cdenii ] shows the evolution of the central density . 0.5 cm and the lower graph shows the contours at the end of the simulation ( @xmath301 ) . the contours are labeled as in fig . [ fig : conti].,title="fig : " ] 0.5 cm 0.5 cm 0.5 cm for star ii evolved without cooling.,title="fig:",width=302 ] 0.5 cm 0.5 cm in the no - cooling case , star ii has not collapsed to a black hole by the end of simulation ( @xmath302 ) , but is settling to a uniformly rotating core surrounded by a massive torus . figure [ fig : contii ] shows the meridional density contours at the beginning and at the end of the simulation . figure [ fig : omega_ii ] shows the angular velocity profiles at various times . viscosity drives the star to a quasi - equilibrium , rigidly - rotating core surrounded by a low - density disk . we can not exclude the possibility that some of the outer material will slowly accrete onto the uniformly rotating inner core , eventually triggering collapse to a black hole . however the star acquires enhanced pressure support against collapse from viscous heating ( i.e. @xmath303 where @xmath304 ) . hence it may no longer be hypermassive with respect to this new `` hot '' equation of state , as the simulation suggests . during the entire simulation , the star loses 1.2% of its rest mass and 4.5% of its angular momentum due to material flowing out of the grid . figure [ fig : constraints ] shows the l2 norms of the hamiltonian and momentum constraints defined by eqs . ( 59 ) and ( 60 ) of paper i. we see that the violation of all the constraints are smaller than 1% during the entire evolution of @xmath305 . the values of the ratio of kinetic to gravitational potential energy , @xmath57 , for all of the stars we studied decrease with time . figure [ fig : towii ] shows the evolution of @xmath57 for star ii evolved without cooling . viscosity transforms part of the rotational kinetic energy into heat . it also changes the equilibrium configuration of the star significantly , causing a redistribution of various energies . figure [ fig : energies ] shows the time evolution of various energies defined in eqs . ( [ def : m0])-([mih ] ) . the mass of the system decreases by 1.4% due to a small amount of mass flowing out of the grid ( not visible in the graph ) . the rotational kinetic energy @xmath68 decreases slightly . the contraction of the core raises the gravitational binding energy @xmath306 , as well as the adiabatic part of the internal energy @xmath307 . viscous heating generates the thermal energy @xmath308 , which prevents the star from undergoing catastrophic collapse . in the rapid - cooling case , star ii collapses dynamically at time @xmath309 . an apparent horizon appears at @xmath310 . the mass and angular momentum of the final black hole are estimated by solving eqs . ( [ eq : jisco])([eq : q ] ) : @xmath311 and @xmath312 ( @xmath313 ) . about 10% of rest mass is left as an accretion disk . the situations for stars iii and iv are similar . the inner core contracts in a quasi - stationary manner while the outer layers expand . each system evolves into a rigidly - rotating core surrounded by a disk - like envelope . the stars do not collapse to black holes at the end of the simulations whether or not rapid cooling is imposed . again , we do not rule out the possibility that they might collapse to black holes when enough material accretes onto the inner core . from table [ tab : results ] , we see that at the end of the simulation , a large amount of angular momentum is transported to a massive disk . for stars iii and iv , the rest mass of the core @xmath314 is smaller than the rest - mass limit of a supramassive star @xmath315 . for star ii , @xmath314 is slightly smaller than @xmath315 in the absence of cooling , but is slightly greater than @xmath315 in the rapid - cooling limit . for star i , @xmath316 in both the rapid - cooling and no - cooling cases . this suggests that the fate of a hypermassive neutron star depends on whether viscosity can create a rigidly - rotating core with @xmath316 , in which case it will collapse . both viscous heating and the star s initial angular momentum play an important role in the final outcome . a hypermassive neutron star with higher mass and lower angular momentum is prone to collapse , whereas viscous heating tends to suppress the collapse . finally , we study the effect of viscosity on star v , which is non - hypermassive . as expected , the star does not collapse to a black hole , irrespective of cooling . the star eventually evolves into a rigidly - rotating core surrounded by a disk . the fact that the star does not simply become rigidly rotating without shedding mass is due to the fact that viscosity conserves @xmath191 and @xmath177 . for a given @xmath191 and equation of state , there is a maximum value of angular momentum @xmath317 above which a star can no longer maintain rigid rotation without shedding mass at the equator . in the case of star v , it is apparent that @xmath318 . hence viscosity can not force the whole star into rigid rotation . similar results were found in studies of viscous evolution of differentially rotating white dwarfs assuming newtonian gravitation @xcite . the results of the axisymmetric runs described above will not be physically relevant if the models are secularly unstable to bar formation . we evolved stars i and iv in 3d to check for the formation of bars . these models were chosen because , of our five models , they have the highest values of @xmath57 . viscous heating can lead to expansion and , hence , a decrease in @xmath57 . thus , to further increase the chance of bar formation , we performed these runs in the rapid - cooling limit . we superimposed @xmath319 perturbations on the initial data according to eq . ( [ seedbar ] ) for both stars with magnitude @xmath320 , so that @xmath321 initially . both runs were performed in @xmath152-symmetry with a uniform grid of size @xmath322 and outer boundaries in the @xmath41-@xmath42 equatorial plane at @xmath323 for star i and @xmath324 for star iv . to reduce computational costs , the extent of the grid in the @xmath36-direction is only half as large as in the @xmath41- and @xmath42-directions . this setup is feasible because these models are initially highly flattened due to rapid rotation and because their evolution results in an expansion which is largely horizontal . for star i , we find that @xmath325 decreases in magnitude until the code terminates due to the collapse , when @xmath326 . before the collapse , all constraints are satisfied to within @xmath327 while @xmath0 and @xmath177 are conserved to within @xmath328 . for star iv , @xmath325 also decreases , reaching 0.0023 after @xmath329 , when the simulation is terminated . in this case , the constraints are satisfied to within @xmath330 while @xmath0 and @xmath177 are conserved to within @xmath331 . we also find that the rest density contours remain nearly axisymmetric throughout the evolutions of both stars . these results indicate that both stars are stable against secular bar formation on the viscous timescale . we have simulated the evolution of rapidly rotating stars in full general relativity including , for the first time , shear viscosity . our findings indicate that the braking of differential rotation in hypermassive stars always leads to significant structural changes , and often to delayed gravitational collapse . the rest mass , angular momentum , and thermal energy all play a role in determining the final state . we performed axisymmetric numerical simulations of five models to study the influence of these parameters . in the presence of shear viscosity , the most hypermassive model which we studied ( star i ) , collapses to a black hole whether we evolve by ignoring cooling , or by assuming rapid cooling of the thermal energy generated by viscosity however , the viscous transport of angular momentum to the outer layers of the star results in mass outflow and the formation of an appreciable disk . next , we considered three hypermassive models ( stars ii , iii , and iv ) with the same rest mass @xmath191 , but different values of the spin parameter @xmath332 . these models have smaller @xmath191 than star i , and are therefore less prone to collapse . star ii , which has @xmath333 , collapses when evolved in the rapid - cooling limit , leaving behind a disk . but without cooling , this model evolves to a stable , uniformly rotating core with a differentially rotating massive disk . the additional thermal pressure support provided by viscous heating prevents collapse in this case . in contrast , stars iii and iv , which have @xmath334 and 1.1 , respectively , do not collapse even in the rapid - cooling limit . this is sensible because these models have a smaller rest mass than star i , but larger angular momenta than star ii . though the cores of stars iii and iv contract , they are prevented by centrifugal support from reaching the necessary compaction to become dynamically unstable . in both cases , we find low - density disks surrounding uniformly rotating cores . however , our simulations do not rule out the possibility that slow accretion of the disk material could eventually drive the uniformly rotating cores to collapse . disk formation also occurs for star v , which is differentially rotating but non - hypermassive . since there exist stable , uniformly rotating models with the same rest mass , the braking of differential rotation in this case does not result in collapse . however , differentially rotating stars can support larger @xmath57 than uniformly rotating stars . in the case of star v , there does not exist a uniformly rotating star with the same ( high ) angular momentum and rest mass , so that mass shedding must take place as viscosity drives the star to uniform rotation . in the final state , we find a rigidly - rotating core surrounded by a low - density , disk . since results obtained from our axisymmetric code are physically reliable only for models which are not subject to nonaxisymmetric instabilities , we evolved stars i and iv in 3d to check for such instabilities . previous studies in newtonian gravity have found that the secular , viscosity - driven bar instability in uniformly rotating stars should set in when @xmath335 @xcite . when general relativity is taken into account , the threshold value can be somewhat higher @xcite . thus , of all of our models , stars i and iv have the best chances of developing bars since they have the highest @xmath57 . we introduced an initial bar - shaped perturbation and ran these cases in the rapid - cooling limit . we found that , in both cases , the small initial perturbation decays and no bar is formed . this is somewhat surprising since @xmath57 is well above 0.14 in both of these cases . we plan to address this issue in a future report . for the evolution of each of our five models , we find that a massive disk or torus forms in the final state . the disk typically carries @xmath336 of the rest mass of the initial configuration . viscosity transports angular momentum from the interior of the star to the more slowly rotating exterior . the exterior regions then expand to accommodate the additional centrifugal force , forming a low - density disk . the inner core becomes rigidly rotating and , in some cases , undergoes gravitational collapse . the disk , however , remains differentially rotating since viscosity acts much more slowly in low - density regions . for cases in which black holes are formed , the mass of the disk may be estimated by integrating the rest - mass density for those fluid elements which have specific angular momentum @xmath337 greater than the value at the isco , @xmath251 [ see eq . ( [ eq : deltam0 ] ) ] . the estimates obtained in this way agree reasonably well with the results of our numerical simulations . particularly good agreement was found for the case of star i with no cooling , for which we were able to extend the evolution some @xmath338 beyond the first appearance of an apparent horizon . the rest mass and angular momentum of the disk surrounding the rotating black hole could then be calculated directly and agreed well with the estimates . we expect that excision techniques will continue to be crucial in establishing the final fate of systems involving matter surrounding black holes . in a recent paper , shibata @xcite numerically simulated collapses of marginally stable , supramassive stars . these supramassive models were constructed using polytropic equations of state with @xmath339 and rotate at the mass - shedding limit with @xmath340 . shibata found that the collapse of these stars results in kerr black holes and that no more than @xmath341 of the initial rest mass remains outside of the hole . this result is quite different from our finding that disks are usually present following collapse . however , the initial data for the two calculations are quite different , as well as our inclusion of viscosity . the analysis of @xcite takes uniformly rotating , unstable configurations as initial data and follows their dynamical evolution . our calculations begin with differentially rotating , stable configurations and follow both their secular ( viscous ) and dynamical evolution . viscosity drives our configurations to uniform rotation . we find that massive disks usually form as by - products of the formation of uniformly rotating cores . this is due primarily to the transport of angular momentum from the inner to the outer layers . in addition , all of our models have @xmath342 . ( large angular momentum is required to generate a hypermassive neutron star in equilibrium . ) since this range is higher than that considered in @xcite , our models more naturally produce disks @xcite . all of the phenomena observed in our simulations follow from the braking of differential rotation in strongly relativistic stars . this may be accomplished by viscosity as shown here , but magnetic fields are likely to be more important . the fate of the hypermassive remnants of binary neutron star mergers may crucially depend on these effects . the loss of differential rotation support in such a remnant may lead to delayed gravitational collapse . this collapse could in turn lead to a delayed gravitational wave burst following the quasi - periodic inspiral and merger signal @xcite . our results indicate that if the remnant is not sufficiently hypermassive , collapse may not occur , at least not until the star cools by radiating away its thermal energy . understanding the evolution of such merger remnants could aid the interpretation of signals observed by ground based gravitational wave detectors , such as ligo , virgo , geo , and tama . in addition , short - duration grbs are thought to result from mergers of binary neutron stars or neutron star - black hole systems @xcite . in this scenario , the grb may be powered by accretion from a massive torus or disk surrounding a rotating black hole . we have demonstrated that such disks are easily produced during the evolution of hypermassive neutron stars . the braking of differential rotation may also be important in neutron stars formed in core collapse supernovae . nascent neutron stars are probably characterized by significant differential rotation ( see , e.g. , @xcite and references therein ) . conservation of angular momentum during the collapse is expected to result in a large value of @xmath57 . however , uniform rotation can only support small values of @xmath57 without shedding mass ( @xcite , chap . thus , nascent neutron stars from supernovae probably rotate differentially . if the induced differential rotation is strong enough , hypermassive neutron stars can form . their subsequent evolution and final fate then depends on the presence of viscosity or magnetic fields . such considerations may be important for long - duration grbs in the collapsar model @xcite . in this model , the grb is powered by accretion onto the central black hole formed through core collapse in a massive star . several interesting astrophysical systems undergo secular evolution in strongly gravitating environments . in this paper , we have shown that it is possible to study secular effects that occur over many dynamical timescales using hydrodynamic computations in full general relativity . we consider this an important step toward future numerical explorations of secular effects in other contexts . in particular , we plan to incorporate mhd into our evolution code , as magnetic braking probably acts more quickly than viscosity to destroy differential rotation in many systems , like neutron stars or supermassive stars @xcite . our results have also raised the following interesting question : under what circumstances are differentially rotating , compressible neutron stars with high @xmath57 unstable to nonaxisymmetric modes ? we plan to address this issue in a future report . the calculations for this paper were performed at the national center for supercomputing applications at the university of illinois at urbana - champaign ( uiuc ) . this paper was supported in part by nsf grants phy-0090310 and phy-0205155 and nasa grant nag 5 - 10781 at uiuc . in this appendix , we describe the thermal properties of our configurations . the dissipation of rotational energy by viscosity heats the stars , but they may be cooled by radiation ( e.g. neutrino radiation ) . the presence of radiation contributes a term @xmath343 to the stress tensor : @xmath344 , with @xmath34 given by eq . ( [ tuv ] ) . this modifies the equations of motion ( [ eom ] ) to @xmath345 where @xmath346 is the 4-force density due to radiation ( see @xcite ) . the specific entropy @xmath347 of a fluid element with temperature @xmath68 and number density @xmath348 changes when there is heating and cooling according to @xmath349 where @xmath211 is the proper time along the element s worldline . here , we have separated the contributions from viscosity and radiation to the heating rate . the quantity @xmath350 is the viscous heating rate per unit volume , which comes from the @xmath351 term in eq . ( [ evolve_estar ] ) . in terms of the thermal energy density @xmath352 and viscous timescale @xmath65 , @xmath350 is roughly @xmath353 in general , a fluid can be heated and cooled by the presence of a radiation field . the energy equation becomes @xmath354 where the last equality arises from evaluating @xmath355 in the comoving orthonormal frame of the fluid , where @xmath356 . then @xmath357 where the integral is evaluated in the comoving frame and @xmath358 , @xmath359 , and @xmath360 are the opacity , intensity , and emissivity at frequency @xmath17 @xcite . for applications of interest here , radiation mediates _ net _ cooling of the viscous - heated fluid . hence , we can set @xmath361 for simplicity . the first law of thermodynamics @xmath362 and eq . ( [ ideal_p ] ) give @xmath363 here we define the entropy parameter @xmath105 by @xmath364 , where , in general , @xmath365 . the form of @xmath366 will depend on the details of the neutron star s microphysics , but it must have the property that @xmath367 when @xmath368 , where @xmath369 is the value of @xmath105 for the unheated fluid ( i.e. no emission from a zero - entropy fluid ) . accordingly , we replace eq . ( [ g0eqn ] ) for @xmath366 by the following illustrative form @xmath370/\tau_{\rm cool}\ , \ ] ] where @xmath371 is a constant and @xmath126 is the radiation timescale . combining equations ( [ dsdtau])-([cooling_rate ] ) , we find @xmath372}{\tau_{\rm cool}}\right\ } \ . \label{evolve_kappa}\ ] ] in the limit @xmath127 , radiative cooling is unimportant and @xmath105 increases due to viscous heating . we refer to this regime as the _ no - cooling _ limit . if @xmath128 , then the first term on the right hand side of eq . ( [ evolve_kappa ] ) may be dropped in relation to the second , giving @xmath373 thus , @xmath105 is exponentially driven to @xmath369 . we refer to this regime as the _ rapid - cooling _ limit , whereby the thermal energy generated by viscosity is radiated immediately and does not heat the gas . in effect , @xmath374 in this limit . in practice we implement this limit by omitting the @xmath375 in eq . ( [ evolve_estar ] ) . though we consider only these two limits in our analysis , we expect that , in reality , heating will dominate in some regimes and cooling in others . we treat both limiting cases in our simulations . w. h. press , and s. a. teukolsky , astrophys . j. , * 181 * , 513 ( 1973 ) ; d. lai , f. a. rasio , and s. l. shapiro , astrophys . j. supp . , * 88 * , 205 ( 1993 ) ; d. skinner , and l. lindblom , astrophys . j. , * 461 * , 920 ( 1996 ) . s. bonazzola , j. frieben , and e. gourgoulhon , astrophys . j. , * 460 * , 379 ( 1996 ) ; s. l. shapiro , and s. zane , astrophys . j. supp . , * 117 * , 531 ( 1998 ) ; t. d. girolamo , and m. vietri , astrophys . j. , * 581 * , 519 ( 2002 ) ; d. gondek - rosinska , and e. gourgoulhon , phys . d , * 66 * , 044021 ( 2002 ) . n. stergioulas , and j. l. friedman , astrophys . j. , * 492 * , 301 ( 1998 ) ; s. morsink , n. stergioulas , and s. blattning , astrophys . j. , * 510 * , 854 ( 1999 ) ; s. yoshida , l. rezzolla , s. karino , and y. eriguchi , astrophys . j. , * 568 * , l41 ( 2002 ) . h. o. kreiss and j. oliger , _ methods for the approximate solution of time dependent problems _ , garp publication series no . 10 ( world meteorological organization , geneva , 1973 ) ; a. m. abrahams , g. b. cook , s. l. shapiro , and s. a. teukolsky , phys . d * 49 * , 5153 ( 1994 ) ; m. w. choptuik , e. w. hirschmann , s. l. liebling , and f. pretorius , class . quant . grav . * 20 * , 1857 ( 2003 ) . what appears to be a drift in @xmath241 due to numerical error becomes visible towards the end of the simulation . this makes the extrapolated value of @xmath241 less reliable than the values of @xmath232 and @xmath239 . g. s. bisnovatyi - kogan , ya . b. zeldovich , and i. d. novikov , sov . astron . * 11 * , 419 ( 1967 ) ; t. w. baumgarte and s. l. shapiro , astrophys . j. * 526 * , 941 ( 1999 ) ; k. c. b. new and s. l. shapiro , astrophys . j. * 548 * , 439 ( 2001 ) .

viscosity and magnetic fields drive differentially rotating stars toward uniform rotation , and this process has important consequences in many astrophysical contexts . for example , merging binary neutron stars can form a `` hypermassive '' remnant , i.e. a differentially rotating star with a mass greater than would be possible for a uniformly rotating star . the removal of the centrifugal support provided by differential rotation can lead to delayed collapse of the remnant to a black hole , accompanied by a delayed burst of gravitational radiation . both magnetic fields and viscosity alter the structure of differentially rotating stars on secular timescales , and tracking this evolution presents a strenuous challenge to numerical hydrodynamic codes . here , we present the first evolutions of rapidly rotating stars with shear viscosity in full general relativity . we self - consistently include viscosity in our relativistic hydrodynamic code by solving the fully relativistic navier - stokes equations . we perform these calculations both in axisymmetry and in full 3 + 1 dimensions . in axisymmetry , the resulting reduction in computational costs allows us to follow secular evolution with high resolution over dozens of rotation periods ( thousands of @xmath0 ) . we find that viscosity operating in a hypermassive star generically leads to the formation of a compact , uniformly rotating core surrounded by a low - density disk . these uniformly rotating cores are often unstable to gravitational collapse . we follow the collapse in such cases and determine the mass and the spin of the final black hole and ambient disk . however , viscous braking of differential rotation in hypermassive neutron stars does not always lead to catastrophic collapse , especially when viscous heating is substantial . the stabilizing influences of viscous heating , which generates enhanced thermal pressure , and centrifugal support prevent collapse in some cases , at least until the star cools . in all cases studied , the rest mass of the resulting disk is found to be 10 - 20% of the original star , whether surrounding a uniformly rotating core or a rotating black hole . this study represents an important step toward understanding secular effects in relativistic stars and foreshadows more detailed , future simulations , including those involving magnetic fields .

by @xmath3 we denote the free group on @xmath4 . let @xmath5 be the normal closure of the defining relators @xmath6 in the free group @xmath3 and @xmath7 be the quotient group @xmath8 . for any word @xmath9 , its area is defined by the minimal number @xmath10 where @xmath11 @xmath12 . using van kampen s lemma @xcite , the area of @xmath13 is equal to the smallest number of cells in a van kampen diagram if its boundary label is @xmath13 . if two words @xmath14 are equal in @xmath7 then we denote by @xmath15 the number @xmath16 . the dehn function @xmath17 is the map from @xmath18 to itself defined as @xmath19 where @xmath20 is the length of the word @xmath13 . the r.thompsons group @xmath21 was discovered by richard thompson in the 1960s . the group @xmath21 is torsion - free , and it can be defined by the following presentation @xmath22 where @xmath23 . @xmath21 is finitely presented , it can be given by @xmath24 where @xmath25 for any @xmath26 . for richard thompson s group @xmath0 , it has the following finite presentation : @xmath27 where @xmath28 for any @xmath26 . let @xmath29 , @xmath30 be two non - decreasing functions from @xmath18 to itself . @xmath31 means that there exists a positive integer constant @xmath32 such that @xmath33 for all @xmath34 . @xmath35 if and only if @xmath31 and @xmath36 . for a finitely presented group there exists a unique dehn function , modulo the equivalence relation @xmath37 . the group has solvable word problem if and only if its dehn function has s recursive upper bound @xcite . a finitely presented group is word - hyperbolic group if and only if its dehn function @xmath38 @xcite . in 1997 , guba and sapir @xcite proved that the dehn function @xmath39 of group @xmath21 is strictly subexponential , namely @xmath40 . after one year , guba @xcite proved that the dehn function of @xmath21 satisfies @xmath41 . finally , guba @xcite proved that @xmath42 in 2006 . for r.thompsons group @xmath0 , guba @xcite proved that @xmath43 . we improve this result as the following : [ t ] _ the dehn function of r.thompsons group _ @xmath0 _ satisfies polynomial upper bound and _ @xmath1 . in this section , we improve some inequalities by using van kampen diagrams which shall be used to estimate the dehn function of @xmath0 in next section . [ 1 ] _ for any _ @xmath44 , \(1 ) @xmath45 \(2 ) @xmath46 \(3 ) @xmath47 for ( [ l11 ] ) , we just use the relation @xmath48 one time , @xmath49 now let us prove ( [ l12 ] ) . let @xmath50 . it is easy to see that @xmath51 , @xmath52 . at first , we prove the case @xmath53 , @xmath54 . consider the following van kampen diagram : applying ( [ l11 ] ) the above diagram shows that @xmath55 by the result of guba s which says the dehn function of r.thompson group @xmath21 is quadratic . we have @xmath56 @xmath57 @xmath58 so we get @xmath59 . for @xmath60 , we consider the following diagram which shows that @xmath61 by guba s result . so we proved ( [ l12 ] ) . for ( [ l13 ] ) , let @xmath62 . clearly , @xmath63 . now let @xmath26 , consider the following diagram shows that @xmath64 . so we have that @xmath65 , which obtains ( [ l13 ] ) . [ 2 ] _ let _ @xmath66 _ _ , _ _ @xmath67 , @xmath68 _ be integers . _ \(1 ) @xmath69 \(2 ) @xmath70 \(3 ) @xmath71 \(4 ) @xmath72 \(5 ) @xmath73 _ each of the equalities _ ( [ l21 ] ) ( [ l22 ] ) ( [ l23 ] ) ( [ l24 ] ) _ needs _ @xmath74 _ elementary steps and _ ( [ l25 ] ) _ needs _ @xmath75 _ steps_. for ( [ l21 ] ) , in case @xmath76 and consider the following diagram the word is @xmath77 labelled by the bottom path , we see that @xmath78 . in case @xmath79 . if @xmath80 , then @xmath81 . if @xmath82 , then the following diagram shows that @xmath83 . for ( [ l23 ] ) , lemma [ 1 ] and the following diagram shows that @xmath84 . now we return to prove ( [ l21 ] ) , in case @xmath85 . we consider the following diagram and apply ( [ l23 ] ) and ( [ l21 ] ) we have @xmath86 . for ( [ l22 ] ) and ( [ l24 ] ) , they can be obtained from ( [ l21 ] ) and ( [ l23 ] ) . in addition , they all need @xmath74 elementary steps . finally , let us prove ( [ l25 ] ) . we construct the following diagram so @xmath87 , which implies @xmath88 . the definition of the complexity @xmath89 which will be occured in the following lemma can be found in @xcite and we improve the corresponding lemma in it . [ 3 ] _ let _ @xmath90 _ be a positive word _ , @xmath91 . _ then there exist a positive word _ @xmath13 _ and an integer _ @xmath92 _ such that _ @xmath93 _ equals _ @xmath94 _ in _ @xmath0 _ and _ @xmath95 , _ where _ @xmath96 . we prove the lemma by induction on @xmath97 , which @xmath97 is the length of the word @xmath90 . it is obviously in the case of @xmath98 . now let @xmath99 . then we can write @xmath100 for some @xmath101 . by the induction assumption , set @xmath102 , we have a positive word @xmath103 , an integer @xmath104 , such that @xmath105 and @xmath106 . consider several cases . \(1 ) @xmath107 . applying lemma [ 2 ] we have @xmath108 we take @xmath109 . then we can obtain @xmath110 . we now compute the complexity of @xmath13 @xmath111 \(2 ) @xmath112 . in this case , @xmath113 . if @xmath114 , we take @xmath115 , @xmath116 . if @xmath117 , we take @xmath118 , @xmath119 . if @xmath120 , then we take @xmath121 , @xmath119 . it is easy to verify by using lemma [ 2 ] in all these cases that @xmath122 and @xmath95 . let @xmath13 be a word of length @xmath34 over the alphabet @xmath123 , then we claim that there exists positive words @xmath124 and an integer @xmath125 such that @xmath126 equals @xmath13 in @xmath0 , @xmath127 and @xmath128 . if @xmath129 , the claim is trivial . let @xmath130 . we write @xmath131 , where @xmath132 or @xmath133 . for @xmath103 by the inductive assumption , there exist positive words @xmath134 of complexity @xmath135 and an integer @xmath136 such that @xmath137 in @xmath0 . \(1 ) @xmath138 . let @xmath139 . after a simple calculation we have @xmath140 . if @xmath141 , then @xmath142 , @xmath143 . if @xmath144 , then by lemma [ 2 ] @xmath145 . in this case , we set @xmath146 , @xmath147 . @xmath148 . and we have the following inequality @xmath149 ( 2)@xmath150 . by @xciteand the lemma in @xcite , there exist a positive word @xmath151 , integers @xmath152 such that @xmath153 , @xmath154 , @xmath155 . if @xmath141 , we just take @xmath156 and @xmath142 . now let @xmath157 . if @xmath158 , then take @xmath147 , @xmath146 . so clearly by lemma [ 2 ] , @xmath159 . if @xmath160 . \(3 ) @xmath133 . in this case , it is similar to be obtained from @xcite , but we have the inequality more precisely @xmath168 thus we have proved the claim by induction . now it is not difficult to get @xmath169 , where @xmath13 is any word of length @xmath167 on the alphabet @xmath170 and @xmath171 in @xmath0 . baumslag , g.,miller , c.f . , short , h. , isoperimetric inequalities and the homology of groups . invent . math . * 113 * , 531 - 560(1993 ) . egbert r. van kampen . , on some lemmas in the theory of groups . _ amer.j.math._ , 55:268 - 273 , 1933 . gersten , s.,isoperimetric and isodiametric functions of finite presentations . in : geometric group theory , vol.1(sussex1991 ) . * 181*,79 - 96(1993 ) . guba , v. s. and m.v . sapir , the dehn function and a regular set of normal forms for r. thompson s group @xmath21 , _ j.austral . a , * 62*(1997),315 - 328 . guba , v. s. , polynomial upper bounds for the dehn function fo r.thompsons group f. j.group theory * 1*,203 - 211(1998 ) . guba , v. s. , polynomial isoperimetric inequalities for the richard thompson s groups @xmath21 , @xmath0 , and @xmath172 . in : algorithmic problems in groups and semigroups , ed . by j .- c . birget et al . , pp . 91 - 120 . boston , berlin : birkhuser 2000 . guba , v. s. , the dehn function of richard thompson s group f is quadratic . 163 , 313 - 342(2006 ) . j.w.cannon , w.j.floyd , and w.r.parry , introductorary notes on richard thompson s groups , _ enseign ( 2 ) , * 42*(1996 ) , 215 - 256 . madlener , k. , otto , f. , pseudo - natural algorithms for the word problem for finitely presented monoids and groups . . comput . * 1 * , 383 - 418(1985 ) . m.gromov , hyperbolic groups , in _ essays in group theory _ , s.gersten , ed . , msri publications 8 , springer - verlag , berlin , new york , heidelberg , 1987,75 - 263 . noel brady , tim riley and hamish short , the geometry of the word problem for finitely generated groups . advanced courses in mathematics crm barcelona , birkhuser , basel , 2007 . isbn 3 - 7643 - 7949 - 9 .

we improve guba s result about the dehn function of r.thompsons group @xmath0 and get that @xmath1 , where @xmath2 is the dehn function of group @xmath0 .

in many nonlinear continuous systems dissipative structures branch out of a homogeneous basic state when the external stress exceeds a critical threshold . examples for these transitions are taylor - couette flow , rayleigh - bnard convection , binary - fluid convection , flame - front propagation , and some chemical or biological processes @xcite . often , for a fixed configuration of parameters and boundary conditions a continuous or discrete family of patterns with different wave numbers is stable . their stability regime , e. g. , a band of wave numbers might be limited by the possibility of resonant triad interactions of modes like those described by the eckhaus or benjamin - feir mechanism @xcite . the stable structures within such a band can be generated by appropriately engineered time histories of the parameters and/or by properly changing the boundary conditions , e. g. , the system size . the most intensively investigated examples in this respect are the structures of taylor vortices @xcite in an annulus between concentric cylinders of which the inner one rotates and convective roll patterns in horizontal layers of one - component fluids @xcite or binary mixtures heated from below @xcite . this multiplicity of solutions of the underlying nonlinear partial differential equations that stably coexist for a fixed configuration of parameters and boundary conditions seems to disappear in an open - flow system : recent numerical simulations of rayleigh - bnard convective rolls traveling downstream in an imposed horizontal poiseuille flow showed @xcite that their structure is uniquely selected i. e. it is independent of parameter history , initial conditions , and system size in the absolutely unstable regime . this is the parameter regime of an open - flow system in which the secondary pattern starting , e. g. , from a spatially localized perturbation can grow in upstream as well as in downstream direction @xcite . by contrast , in the convectively unstable regime @xcite initial perturbations are blown out of the system both , the upstream as well as the downstream facing front of the growing structure move downstream . in the absolutely unstable regime the structure expansion proceeds until the upstream ( downstream ) moving front encounters in a finite system the inlet ( outlet ) and adjusts to the inlet ( outlet ) boundary condition . the final pattern resulting in such a situation shows a characteristic streamwise profile of the amplitude growing with increasing distance from the inlet and of the wave number variation , and a characteristic global oscillation frequency associated with the downstream motion of the pattern . in this work we elucidate in numerical and analytical detail how such a uniquely selected spatiotemporal pattern structure can be understood as a nonlinear eigenvalue problem with the oscillation frequency being the eigenvalue and the profiles of pattern intensity and wave number determining the corresponding eigenfunction . we also show how this pattern selection process is related to the one occurring behind a front or `` domain wall '' that spatially separates an unstable , homogeneous state from a stable , structured state . to that end we present results of extensive numerical and analytical investigations of vortex patterns in the annulus of the taylor - couette setup with an externally imposed axial through - flow . for small through - flow rates and small rotation rates of the inner cylinder the structure of propagating vortex ( pv ) flow with vortices being advected in downstream direction is rotationally symmetric . only for higher through - flow rates , which are not investigated here , there is a bifurcation @xcite to spirals @xcite . we have performed numerical simulations of the full , rotationally symmetric , two dimensional ( 2d ) navier - stokes equations ( nse ) . they are compared with our numerical and analytical results obtained from the appropriate @xcite 1d ginzburg - landau amplitude equation ( gle ) approximation to the problem of pv flow and with experimental results @xcite the eigenvalue problem of the pattern selection by the imposed flow can best be analyzed and explained within the gle framework . therein , the complex amplitude @xmath0 of the pv flow depends in the absolutely unstable regime on the streamwise position @xmath1 and on time @xmath2 in a multiplicative way only , @xmath3 after transients have died out . the @xmath1-independent frequency @xmath4 and the complex , @xmath1-dependent amplitude @xmath5 that describes the streamwise variation of pattern modulus and wave number are simultaneously fixed via a solvability condition in the form of a nonlinear eigenvalue problem . the selection of @xmath4 and @xmath5 seems to result from requiring the spatial variation of the amplitude to be as small as possible under the imposed boundary conditions for @xmath6 at the ends of the annulus . approaching the border between the absolutely and convectively unstable regimes the pattern selection mechanism becomes linear : for driving and through - flow rates on this border line the selected frequency is the one resulting from a linear front whose spatiotemporal behavior is governed by the fastest growing linear mode . the latter is identified by a particular saddle of the complex linear dispersion relation over the complex wave number plane @xcite . now , the linear dispersion relations of nse @xcite and gle differ for supercritical control parameters . and therefore the pv structures selected by nse or gle differ in a characteristic way . it should be emphasized that the structural dynamics of pattern formation in the convectively unstable regime at larger through - flow rates and/or smaller driving rates substantially differs from the one investigated here in the absolutely unstable regime . the latter regime is governed by nonlinear contributions in the balance equations ; the resulting patterns are uniquely selected and insensitive to initial conditions , parameter history , and small perturbations . on the other hand , in the convectively unstable regime that has attracted more experimental activities lately @xcite the growing patterns are sensitive to initial conditions and perturbations . thus , e. g. , the noise sustained patterns @xcite occurring in this regime depend on details of the spatiotemporal properties of the perturbation source . the taylor - couette system @xcite with an imposed axial through - flow has been investigated as a well defined open - flow system theoretically @xcite and experimentally @xcite since the beginning 1930s . linear stability analyses of the basic state to traveling axisymmetric vortices were performed using various approximations , e. g. , for the narrow - gap limit , or simplified azimuthal velocity , or axial through - flow profiles @xcite , and later on for various aspect ratios fixed by the diameters of both cylinders @xcite . also , many experiments and comparisons with the theoretical predictions were done @xcite . our paper is organized as follows : in sec . [ system ] we describe the system , the subregions of absolute and convective instability , and our methods of investigation . furthermore , we recapitulate the gle . the next section presents the spatiotemporal behavior of pv patterns obtained numerically for two different boundary conditions . in sec . [ patternselection ] we analytically and numerically elucidate the pattern selection observed within the gle and the nse . we compare the results with each other , with front propagation , and with experiments . the last section gives a conclusion . we investigate time - dependent , rotationally symmetric vortex structures in a taylor - couette apparatus with an externally enforced axial flow . the viscous , incompressible fluid is confined to the annulus between two concentric cylinders of inner radius @xmath7 and outer radius @xmath8 . the setup is characterized by two geometric parameters : the radius ratio @xmath9 and the aspect ratio @xmath10 , i.e. , the quotient of the axial extension of the annulus and the gap width @xmath11 . mostly we have used in our numerical simulations an aspect ratio of @xmath12 and a radius ratio of @xmath13 . the outer cylinder is always kept at rest , while the inner one has a rotation rate @xmath14 . in addition we impose a small through - flow in axial direction . the boundary conditions at @xmath7 and @xmath8 were always no slip . the conditions at the two ends @xmath15 and @xmath16 of the annulus are explained in sec . [ boundaryconditions ] . the flow pattern is described by the momentum balance equation for the velocity field @xmath17 , the navier - stokes equations @xmath18 and the continuity equation @xmath19 which reflects the incompressibility of the fluid . here @xmath20 is the kinematic viscosity , @xmath21 the mass density , and @xmath22 the pressure . the system is characterized by two dimensionless control parameters . the taylor number @xmath23 is given by the squared rotation rate @xmath14 of the inner cylinder . the reynolds number @xmath24 is proportional to the mean axial through - flow velocity @xmath25 . for an axially uniform system the homogeneous basic flow state @xcite @xmath26 is a linear superposition of circular couette flow ( ccf ) @xmath27 in azimuthal direction and of annular poiseuille flow ( apf ) @xmath28 in axial direction . we scale lenghts by @xmath29 , times by the radial diffusion time @xmath30 , azimuthal velocities by the velocity of the inner cylinder @xmath31 , radial and axial velocities by @xmath32 . then @xmath33 @xmath34 @xmath35.\ ] ] here , @xmath36 is the dimensionless axial pressure gradient driving the apf . at the critical taylor number @xmath37 @xcite , which depends on the through - flow rate , the basic flow becomes unstable to rotationally symmetric , axially extended pv perturbations via an oscillatory instability . there , a nonlinear pv solution branches off the basic flow in an axially infinite system . we consider the _ deviation _ @xmath38 of the velocity field from the basic flow ( [ bflow ] ) as the order - parameter field to characterize the secondary pv structure . we use the relative control parameter @xmath39 corresponding to @xmath40 to measure the distance from the onset of pv flow for @xmath41 and of stationary taylor vortex flow for @xmath42 , respectively . in this notation @xmath43 is the critical threshold for onset of pv flow . the relation between @xmath44 and @xmath45 is @xmath46 the shear forces associated with the axial through - flow sligthly stabilize the homogeneous basic state , so @xmath47 slightly increases with @xmath48 @xcite . for similar reasons a lateral poiseuille shear flow suppresses the onset of convection rolls with axes perpendicular to the flow in a bnard setup of a fluid layer heated from below @xcite . close to the bifurcation threshold @xmath37 of pv flow , i.e. , for small @xmath44 , the flow has the form of a harmonic wave , e.g. , @xmath49 with a complex amplitude @xmath0 that is slowly varying in @xmath1 and @xmath2 . the critical wave number @xmath50 , frequency @xmath51 @xcite , and eigenfunction @xmath52 @xcite appearing in eq . ( [ hwave ] ) have been obtained from a linear stability analysis of the basic flow state as functions of @xmath48 . the complex vortex amplitude @xmath53 is given by the solution of the 1d complex gle @xmath54 dot and primes denote temporal and spatial derivatives in the @xmath1-coordinate , respectively . all coefficients of the gle have been calculated @xcite as functions of @xmath48 for several radius ratios @xmath55 . as a consequence of the system s invariance under the combined symmetry operation @xmath56 the coefficients @xmath57 , @xmath58 , @xmath59 are even in @xmath48 while the group velocity @xmath60 and the imaginary parts @xmath61 , @xmath62 , @xmath63 are odd in @xmath48 @xcite . it should be noted that the control parameter range of @xmath44 over which ( [ hwave ] ) gives an accurate description of the full velocity field of pv flow , say , on a percent level is indeed very small : the asymmetry between radial in- and outflow intensities rapidly grows with @xmath44 and causes higher axial fourier contributions @xmath64 @xcite to the velocity field that are discarded in the @xmath65 asymptotics of the gle approximation ( [ hwave ] ) . however , the modulus of the first fourier mode of the vortex structures agrees for @xmath66 as well as for @xmath67 quite well with the one predicted by the gle cf . [ boundaryconditions ] . on the other hand , the pv structure selected according to the gle differs from the one resulting from the full field equations cf . sec . [ patternselection ] . for small @xmath45 and @xmath48 the control parameter plane is divided into three stability regimes - cf . [ controlparameterplane ] - characterized by different growth behavior of _ linear _ perturbations of the basic flow state . below the critical threshold @xmath47 for onset of pv flow ( dashed line in fig . [ controlparameterplane ] ) any perturbation , spatially localized as well as extended , decays . this is the parameter regime of absolute stability of the basic state . perturbations of the basic state can grow only for @xmath68 . however , in the presence of through - flow one has to distinguish @xcite between the spatiotemporal growth behavior of spatially localized perturbations and of spatially extended ones . the latter having a form @xmath69 can grow above @xmath70 ( re ) in fact @xmath70 is determined as the stability boundary of the basic state against extended harmonic perturbations . on the other hand , a spatially localized perturbation , i.e. , a wave packet of plane wave perturbations is advected in the so - called convectively unstable parameter regime faster downstream than it grows while growing in the comoving frame it moves out of the system @xcite . thus , the downstream as well as the upstream facing intensity front of the vortex packet move into the same direction , namely , downstream . in this regime the flow pattern that results from a spatially localized source , which generates perturbations for a limited time only , is blown out of any system of finite length and the basic state is reestablished . in the absolutely unstable regime ( shaded region in fig . [ controlparameterplane ] ) a localized perturbation grows not only in downstream direction but it grows and spatially expands also in upstream direction until the upstream propagating front encounters the inlet in a finite system . the final pattern resulting in such a situation shows in downstream direction a characteristic axial intensity profile under which the pv flow develops with increasing distance from the inlet . within the framework of the amplitude equation the boundary ( full line in fig . [ controlparameterplane ] ) between absolute and convective instability is given by @xcite @xmath71 corresponding to @xmath72 . thus the absolutely unstable regime ( shaded region in fig . [ controlparameterplane ] ) is characterized by @xmath73 or , equivalently , by the reduced group velocity @xmath74 being smaller than 2 . it should be mentioned that the gle approximation ( [ mucconv ] ) of @xmath75 describes the boundary between absolute and convective instability resulting from the nse @xcite very well for the small reynolds numbers considered here . the linear growth analysis of modes @xmath76 $ ] shows that for small through - flow rates the homogeneous basic state becomes first unstable to axisymmetric pv flow @xcite . up to @xmath77 these patterns are also detected experimentally @xcite . however , at larger @xmath48 one observes stationary spirals and mixed flow patterns @xcite in addition to the bifurcation of propagating spirals @xcite . the latter are predicted by the linear stability analysis to branch off the basic state at @xmath78 @xcite . the pv patterns occuring at small through - flow rates ( @xmath79 ) that are discussed here are rotationally symmetric . therefore it is sufficient to solve the hydrodynamic field equations in an @xmath80-@xmath1 cross section of the annulus to describe the resulting field @xmath81 . we have performed numerical simulations of the 2d nse . they are compared with analytical and numerical results obtained from the 1d gle . the latter was solved with a cranck - nicholson algorithm using central differences for spatial derivatives with a resolution of @xmath82 grid points per unit length @xmath29 . the solution of the nse was obtained with a time - dependent finite - differences marker and cell ( mac ) algorithm @xcite with pressure and velocity being iteratively adapted to each other with the method of artificial compressibility @xcite . also here the spatial resolution was @xmath82 grid points per unit length @xmath29 . the temporal stepsize was @xmath83 times the radial diffusion time @xmath84 . when comparing finite - differences solutions of the nse with experiments or with analytical properties , e.g. , of the gle we take into account that the critical properties of the finite - differences mac code differ slightly from the latter due to its finite spatiotemporal resolution . in particular the critical taylor number , @xmath85 , of the mac code lies slightly ( less than @xmath86 ) below the theoretical bifurcation threshold cf . table i and @xcite . to find the marginal stability curve @xmath87 of the mac algorithm for axially extended pv perturbations of wave number @xmath88 we analyzed the complex growth rate @xmath89 in systems of length @xmath90 using periodic boundary conditions in axial direction for through - flow rates up to @xmath91 . from this analysis we also obtained the critical values of the frequency @xmath51 , group velocity @xmath60 , wave number @xmath50 , and the parameters @xmath57 and @xmath58 ( table i ) . furthermore , we have cross - checked these results by investigating the evolution of localized perturbations in long systems of lengths @xmath92 , in particular in the convectively unstable regime in a manner that is quite similar to experimental procedures @xcite : we generated tiny , localized pv perturbations of about five vortex pairs with wave numbers close to @xmath50 under an intensity envelope of gaussian shape . they propagate downstream with the group velocity @xmath60 . a fit to the rate of exponential growth of the envelope gives @xmath93 . from the growth of the full width at half maximum we obtain @xmath94 . these identifications are based upon comparing with the temporal evolution of a gaussian perturbation @xcite @xmath95\ ] ] of initial axial extension @xmath96 according to the linearized gle . it yields @xmath97\ ] ] with @xmath98 test runs with twice the lattice points per unit length showed that the differences between the critical properties of the continuous system that were obtained @xcite with a shooting method and the finite - differences system significantly decrease by one order of magnitude . we have also investigated the dependence of nonlinear , saturated pv flow on the numerical discretization . these tests show that the nonlinear vortex structures are basically independent of the discretization provided it is not to coarse . however , one should base the comparison of bifurcated flow structures obtained with different discretizations on the relative control parameter @xmath99 that is influenced via @xmath100 by the discretization in question see also sec . [ finitesize ] . when comparing results obtained for different @xmath44 and @xmath48 from numerical simulations of the nse with those following from the gle we found it sometimes advantageous to present them as functions of the reduced group velocity @xmath101 ( [ vg ] ) . the deviation @xmath102 is a scaled distance from the boundary between the absolutely and convectively unstable regime . its relation to the through - flow reynolds number @xmath48 and the taylor number @xmath103 can be read off from table i. we investigate pv patterns in the absolutely unstable regime in an annulus of finite length with two different end conditions : a basic state boundary condition ( bci ) in sec . [ bsbc ] and an ekman vortex boundary condition ( bcii ) in sec . [ evbc ] . for both boundary conditions numerical simulations have been performed for the parameter combinations marked by symbols in fig . [ controlparameterplane ] . in each case we observe a pattern of vortices propagating downstream under a stationary intensity envelope after transients have died out as shown in fig . [ hiddenlineplot ] . the oscillation frequency @xmath104 of the flow is independent of the radial and axial position while the local wave number @xmath88 , the phase velocity @xmath105 , and the vortex flow intensity varies with @xmath80 and @xmath1 . the frequency and the spatial variation of the pv pattern depends on the control parameters and on the boundary conditions but not on parameter history or initial conditions . here we discuss vortex suppressing boundary conditions that are realized by imposing the homogeneous basic state @xmath106 ( [ bflow ] ) at in- and outlet of the annulus . the flow resulting for this boundary condition resembles the experimental one of babcock _ et al . _ @xcite . there , a system of flow distributors and meshes at the inlet reduces external perturbations penetrating the interior of the annulus and seems also to suppress radial flow @xcite . near the inlet no _ stationary _ ekman vortices are visible in this experiment and the amplitude of the downstream propagating vortices starts with zero or nearly zero @xcite . to illustrate the global properties of the flow patterns we present in the upper part of fig . [ hiddenlineplot ] a hidden - line plot of the axial velocity field @xmath107 . thin lines show snapshots of @xmath107 at the radial position @xmath108 obtained from the nse at successive , equidistantly spaced times after transients have died out . then vortices propagate downstream under a stationary intensity envelope ( thick line ) . this envelope is determined by the temporal extrema of @xmath109 at any z - position . the oscillation frequency of the pv pattern is constant over the entire annulus . sufficiently away from inlet and outlet we observe a bulk region of nonlinear saturated pv flow with spatially uniform amplitude and wavelength . with increasing through - flow this bulk pattern is pushed further and further downstream . the growth length @xmath110 from the inlet over which the amplitude reaches half its saturation value depends on @xmath44 and @xmath48 . it increases and finally diverges when the control parameters @xmath44 , @xmath48 approach the absolute - convective instability border @xmath111 , that is when @xmath101 ( [ vg ] ) reaches @xmath112 . in fig . [ lscaled ] we compare the scaled growth length @xmath113 computed from the amplitude equation ( solid line ) with results from the nse ( symbols ) for various combinations of @xmath45 and @xmath48 . due to the scaling property of the gle @xcite keeping in mind the smallness of the imaginary parts @xmath114 all values for @xmath110 obtained by the gle subject to bci fall onto one curve in the plot of @xmath115 vs. @xmath101 . the open symbols representing the nse results for bci lie very close to the gle curve . full symbols for bcii are discussed in sec . [ evbc ] . for further characterization of the pv flow structure we found a _ temporal _ fourier decomposition of the time - periodic fields , e.g. , @xmath116 to be useful . to that end we first determined the oscillation frequency @xmath104 of the pv pattern and checked that it showed no spatial variation . in fig . [ fouriermodesbsbc]a the zeroth temporal fourier mode @xmath117 and the moduli @xmath118 , @xmath119 , and @xmath120 resulting from the nse are shown by full lines while @xmath118 from the gle is shown by the dashed one . the latter was rescaled by a factor of @xmath121 which comes from comparing the first axial fourier mode of @xmath122 at @xmath42 in an axially periodic system with the gle result of recktenwald _ et al . _ @xcite . as an aside we mention that for the radial velocity @xmath123 having a nodeless radial profile with a single maximum the deviation of the first fourier mode of @xmath124 between finite - differences nse and gle is only @xmath125 at @xmath42 . note that the solution of the gle ( [ gle ] ) @xmath126}\ ] ] oscillates harmonically with frequency @xmath4 under a stationary envelope @xmath127 after transients have died out . therefore , the gle velocity field ( [ hwave ] ) contains no temporal fourier mode other than @xmath128 whereas the solution of the full nse has higher harmonics . in the bulk region the _ temporal _ modes obtained for finite through - flow from the nse grow for small @xmath44 proportional to @xmath129 with relative corrections proportional to @xmath44 . thus , they show the same growth behavior with @xmath44 that the _ axial _ fourier modes @xcite of stationary taylor vortices without through - flow show as a function of @xmath45 . the reason is that all fields in the pv state have the form of propagating waves @xmath130 in the bulk region - denoted by a subscript b. there the wave number @xmath131 and the phase velocity @xmath132 do not vary with @xmath1 . the fourier mode @xmath117 of the pv pattern is not zero everywhere since the variation of the flow amplitude under the fronts causes a secondary , stationary , closed flow pattern there see , e.g. , @xmath117 at @xmath133 and near the outlet in fig . [ fouriermodesbsbc]a . its strength and structure depends on the steepness of the front . for example , an increase of @xmath48 leads to a smaller gradient of the upstream facing front and to weaker stationary secondary flow extending further downstream . the intensity variation ( cf . figs . [ hiddenlineplot ] , [ fouriermodesbsbc]a ) of pv flow under the fronts also causes there a spatial variation in the local wavelength @xmath134 ( fig . [ fouriermodesbsbc]b ) and in the phase velocity @xmath135 with the oscillation frequency @xmath104 of pv flow being constant . the full ( dashed ) line in fig . [ fouriermodesbsbc]b is the wavelength profile @xmath134 selected for bci according to the nse ( gle ) . this figure shows that the gle does not describe the pattern selection quantitatively . the selected wavelength in the bulk region of the nse ( gle ) is smaller ( larger ) than the critical one see also sec . [ patternselection ] . the local wavelength shown in fig . [ fouriermodesbsbc]b was determined from the phase gradient of the first temporal fourier mode @xmath136 at the radial position @xmath137 . we have analyzed @xmath138 and also @xmath139 at other @xmath80 positions and in addition we determined the axial distances between node positions of @xmath123 and @xmath107 . under the fronts there is a significant radial variation of @xmath140 . furthermore , the wavelengths determined via the phase gradients of @xmath138 and @xmath139 differ there from each other and from those obtained via node distances of @xmath107 and @xmath123 . but in the bulk part of the pv structure all these quantities yield the same wavelength @xmath141 . in taylor - couette experiments without through - flow rigid nonrotating end plates bounding the fluid in axial direction induce stationary ekman vortex flow @xcite . these vortices are also detected by tsameret _ et al . _ in experiments with axial through - flow , where meshes at the apertures were used as nonrotating boundaries at in- and outlet @xcite . the second axial boundary condition bcii enforces stationary ekman vortices near the apertures of the annulus . to that end we impose at both ends @xmath142 zero radial flow , zero azimuthal flow , and in axial direction the annular poiseuille flow @xmath143 ( [ wapf ] ) . the spatiotemporal properties of the vortex pattern subject to this bcii can be seen in the lower part of fig . [ hiddenlineplot ] . there we show a hidden - line plot of the axial velocity in the same way and for the same parameters as for the bci pattern in the upper part of fig . [ hiddenlineplot ] . in the immediate vicinity of in- and outlet there are _ stationary _ ekman vortices whose intensity rapidly decreases towards the bulk of the annulus . in addition there is as in the bci case the pv flow structure that _ oscillates _ in time with a z - independent frequency @xmath104 . the oscillation amplitude drops to zero near the apertures due to the boundary conditions , and the stationary ekman vortices increase the growth length @xmath110 of the oscillating structure in comparison to the bci case . these two different flow elements are best separated by a temporal fourier analysis . the results for bcii are shown in fig . [ zerothfouriermodeevbc ] for different through - flow rates . the zeroth temporal mode @xmath117 ( thick line ) represents the stationary ekman vortex flow of the system . the temporally oscillating pv structure is characterized by the modes @xmath144 ( thin lines ) . the ekman vortex structure at the inlet is only slightly affected by the through - flow : the strength of the ekman vortex closest to the inlet decreases somewhat with increasing @xmath48 , while its extension slightly increases . the stationary vortices at the outlet become more and more squeezed together with increasing @xmath48 , and also their intensity reduces . on the other hand , the oscillatory pattern of pv responds dramatically to the through - flow in being more and more pushed downstream . note also that for small @xmath48 where the pv amplitude of , say , @xmath145 overlaps near the inlet with the ekman vortex intensity the latter causes axial oscillations in the harmonics of the pv flow and similarly near the outlet - cf . [ zerothfouriermodeevbc ] . the filled symbols in fig . [ lscaled ] represent the growth length of the pv flow intensity . this length diverges in a similar way at the convective instability border @xmath146 as the one obtained for bci . but due to the presence of ekman vortices at the inlet the characteristic growth length @xmath147 of pv flow is increased by @xmath148 in comparison to the bci case ekman vortices push the pv structure further downstream . the difference @xmath149 decreases with increasing through - flow rate as ekman vortices and pv flow become more and more separated from each other . as in the bci case the zeroth temporal fourier mode exhibits a secondary , stationary , closed flow pattern of low intensity under the fronts of the pv pattern . for small reynolds numbers this pattern is concealed by the ekman vortex flow , whereas it becomes visible for bigger through - flow rates . our investigations of the pv structures show that the axial through - flow causes a unique pattern selection such that the selected structure is independent of history and initial conditions and depends only on the control parameters and boundary conditions . thus , the axial flow causes possible wave numbers within the eckhaus - stable band of stationary taylor vortex patterns without through - flow to collapse to only one uniquely selected pv structure for nonvanishing through - flow rates . however , the pv patterns that are selected according to the gle approximation and to the full nse differ distinctly from each other . we first investigate in sec . [ patternselectiona ] the selection mechanism within the gle framework . in sec . [ patternselectionb ] we compare with nse results and experiments . here we elucidate how the pattern selection mechanism of the gle can be understood as a nonlinear eigenvalue / boundary - value problem where the frequency of the pv pattern is the eigenvalue . thus , the selected pv structure is characterized and determined by the combination of eigenvalue and corresponding eigenfunction . we look for solutions of the gle ( [ gle ] ) of the form ( [ hwavenotransients ] ) @xmath150 } \label{evproblema}\ ] ] with stationary envelope @xmath151 , stationary wave number @xmath152 and constant frequency @xmath153 inserting this solution ansatz into the gle ( [ gle ] ) one obtains the nonlinear eigenvalue problem @xmath154 or , equivalently , @xmath155 [ evproblem ] as a solvability condition with @xmath4 being the eigenvalue . we are interested in solutions @xmath151 and @xmath156 that look like the dashed lines in fig . [ fouriermodesbsbc ] , i.e. , where the variation of @xmath151 and in particular of @xmath156 is `` as small as possible '' . such a solution type seems to be connected with the eigenvalue @xmath4 that is closest to zero . here we consider the boundary conditions @xmath157 at in- and outlet . these requirements fix four boundary conditions namely , @xmath158 which are necessary to solve the gle ( [ gle ] ) . note that the eigenfrequency @xmath4 is in general determined by _ global _ properties and not by the _ local _ variation of the eigenfunctions @xmath151 and @xmath156 , say , at the inlet or in the bulk . nevertheless it is informative and useful for our further discussion to list below relations between @xmath4 and structural properties at the inlet and in the bulk of the annulus . from ( [ evprobleme ] ) one finds that the bci at in- and outlet , @xmath159 , implies the relation @xmath160r'_{in , out } \label{r2r1comp}\ ] ] at @xmath161 . hence , whenever the modulus grows with finite slope , @xmath162 , the boundary condition @xmath159 fixes the wave number at inlet _ and _ outlet to the value @xmath163 @xmath164 that depends only on @xmath48 . this value ensures that the imaginary part of the square bracket in ( [ r2r1comp ] ) is zero . for @xmath42 one obtains @xmath165 as cross _ et al . _ in addition the condition @xmath159 yields via the real part of ( [ r2r1comp ] ) to two relations @xmath166 between the different slopes @xmath167 and curvatures @xmath168 of the modulus at the two respective boundaries that hold independently of @xmath44 . furthermore , one can derive a relation between the eigenfrequency @xmath4 , the wave number @xmath169 , and its slope @xmath170 at inlet and outlet . to that end we consider the axial derivative of ( [ evprobleme ] ) at inlet and outlet with @xmath159 @xmath171 \frac{r''}{r ' } = \xi^2_0 ( 1+ic_1 ) ( \frac{r'''}{r''}+3iq ' ) . \nonumber \\\end{aligned}\ ] ] this allows to solve for @xmath172 and @xmath173 separately . using ( [ qinout],[r2r1 ] ) one obtains the relation @xmath174 note that this equation implies @xmath175 . the relation ( [ omqinout ] ) also demonstrates the nonlocality of the pattern selection mechanism and of the eigenvalue problem . at first sight one might be tempted to infer from the above relation between @xmath4 and @xmath176 that the latter two fix the frequency . however , eq . ( [ omqinout ] ) equally well holds for @xmath177 and the outlet properties do not fix @xmath4 neither . so the correct interpretation of eq . ( [ omqinout ] ) is that the eigenvalue @xmath4 being the characteristic global signature of the pattern fixes the local quantities @xmath170 for the given boundary conditions . the wave number @xmath156 away from in- and outlet in general differs from @xmath178 ) . in order to obtain the full axial profiles of the eigenfunctions @xmath151 and @xmath156 belonging to the eigenvalue @xmath4 one has to solve the eigenvalue problem ( [ evproblem ] ) with the boundary condition @xmath157 . alternatively one can solve numerically the time - dependent gle ( [ gle ] ) . however , when the system size and the control parameters are such that the pv pattern forms a bulk part with a homogeneous modulus @xmath179 and wave number @xmath180 , i.e. , where @xmath181 then , the dispersion relation @xmath182 provides a relation between the frequency eigenvalue @xmath4 , the bulk wave number @xmath180 , and the bulk modulus @xmath183 the equation ( [ omqbulk ] ) establishes together with ( [ omqinout ] ) also a relation between @xmath180 on the one hand and @xmath163 and @xmath175 on the other hand . approaching the convective instability boundary ( [ mucconv ] ) we found that @xmath184 decreases to zero so that the frequency eigenvalue becomes @xmath185 then the bulk wave number approaches according to ( [ omcconv ] , [ omqbulk ] ) the limiting value @xmath186 while the inlet wave number @xmath187 is given by ( [ qinout ] ) . due to the very small imaginary parts @xmath114 the solution ( [ qcconv ] ) with the plus sign has to be discarded , since it corresponds to unphysically large wave numbers . in fig . [ selectedwavelength ] the bulk wavelengths selected according to the gle are shown by halftone symbols . the results in the absolutely unstable regime , @xmath188 , were obtained numerically by integrating the time - dependent gle ( [ gle ] ) . the value shown right at the border , @xmath189 , of the absolutely unstable regime is the analytical expression ( [ qcconv ] ) . note that the selected gle wavelengths are mostly larger than the critical one . it is suggestive to compare properties of pv patterns like the one in the upper part of fig . [ hiddenlineplot ] with those behind an upstream facing front that connects in an axially infinite system the basic state at @xmath190 with the developed pv state at @xmath191 . a _ linear _ growth analysis of the gle ( [ gle ] ) along the lines of ( * ? ? ? vi b 3 ) shows that the far tail of a _ linear _ front of pv perturbations moves with the front velocity @xmath192 in the convectively unstable regime @xmath193 the front propagates downstream so that @xmath194 . in the absolutely unstable regime @xmath195 it moves upstream , i.e. , @xmath196 . and at the boundary @xmath197 the front is stationary @xmath198 . we compare the properties of such a stationary front at @xmath199 with those of the solution @xmath0 ( [ hwavenotransients ] ) with stationary modulus in a semi - infinite system ( @xmath200 ) . the reason for restricting the comparison to @xmath201 is that an upstream moving front in the absolutely unstable regime will be pushed against the inlet whence the spatiotemporal structure of the free front gets modified by the inlet . the far tail of the stationary front resulting from the linear gle is characterized by the local wave number @xmath202 and the oscillation frequency @xmath203 in fact in the linear part of the stationary front the flow amplitude @xmath204}\ ] ] varies with a wave number @xmath205 ( [ qflin ] ) , a spatial decay rate @xmath206 , a temporal growth rate @xmath207 , and an oscillation frequency @xmath208 ( [ omflin ] ) . here @xmath209 is the saddle position of the complex dispersion relation @xmath210 of the linear gle in the complex @xmath211-plane determined by the condition @xmath212{$q_s$}$ & \\ \end{array}\ ] ] for @xmath213 , i.e. , at @xmath197 . so the inlet wave number @xmath187 ( [ qinout ] ) agrees with @xmath214 ( [ qflin ] ) and @xmath215 ( [ omcconv ] ) coincides with @xmath216 ( [ omflin ] ) . thus , right at the border @xmath201 of the absolutely unstable regime the frequency eigenvalue of the pv pattern growing in downstream direction from the inlet at @xmath15 agrees with the oscillation frequency selected by the stationary , _ linear _ front . within the front propagation point of view the pv pattern develops from the basic state with an exponential growth rate @xmath217 of the modulus . this leads for @xmath218 to @xmath219 for @xmath220 . on the other hand , the pv flow intensity in the semi - infinite system in general drops to zero at the inlet with finite @xmath221 and @xmath222 . only at the border line @xmath197 the difference disappears since there @xmath223 for @xmath15 . in the absolutely unstable regime , @xmath224 , the frequency eigenvalues @xmath225 of the gle lie slightly above the limiting value @xmath215 at the border of the absolutely unstable regime . the shaded symbols in fig . [ omvalues ] show for three different @xmath45 how @xmath4 obtained numerically by integrating eq . ( [ gle ] ) approaches with increasing @xmath48 the front frequency @xmath226 ( dashed line ) . for convenience , the merging points with this limit line are marked for the three @xmath45-values investigated here by small halftone symbols . using this frequency for the full nonlinear pv pattern at @xmath201 one obtains from the bulk dispersion relation ( [ omqbulk ] ) an expression for the bulk wave number @xmath227 far behind the front . this bulk wave number behind the front has the opposite sign of the one that is cited in @xcite and ( * ? ? ? ( 10,14 ) ) . an explanation for this might be that the formulas of nozaki and bekki ( * ? ? ? * eqs . 2 , 8 , and 9 ) that have been used in refs . @xcite do not seem to have been transformed to a through - flow situation with an _ upstream _ facing front that joins in upstream direction to the basic state , in our case at @xmath190 . after correcting the sign error , the rough qualitative agreement that was reported in @xcite between the experimental wave numbers @xcite and the erroneous gle results @xcite disappears . in fact , both , the experiments @xcite and our numerical simulations of the nse yield wave numbers that differ in a common distinctive way from the proper gle result ( [ qbulkfront ] ) . as an aside we mention , that the _ nonlinear _ front solution of nozaki and bekki ( * ? ? ? * eqs . 2 - 7 ) yields for our gle ( [ gle ] ) a front that is not stationary at @xmath201 but rather moves with velocity @xmath228 in upstream direction with a bulk wave number @xmath229 . \nonumber \\\end{aligned}\ ] ] so we conclude that the _ nonlinear _ front solution of nozaki and bekki is unrelated to the pv patterns at @xmath201 . furthermore , it was noted @xcite that localized initial perturbations did not evolve into the _ nonlinear _ front solution of nozaki and bekki @xcite . however , @xmath230 and @xmath231 differ for small through - flow only slightly from the respective values @xmath213 and @xmath232 . for example at @xmath233 one obtains @xmath234 and @xmath235 . scaling length and times according to @xmath236 the gle for the reduced amplitude @xmath237 does no longer contain @xmath59 and @xmath44 explicitly but the reduced group velocity @xmath101 ( [ vg ] ) and the coefficients @xmath238 . thus the reduced selected frequency @xmath239 and the selected bulk wave number @xmath240 depends not only on @xmath101 but via @xmath238 also on the reynolds number . this @xmath48-dependence can alternatively be seen via the @xmath48-dependence of @xmath101 and of the @xmath114 s entering ( [ vg ] ) also as an additional @xmath44-dependence . the latter dependence is sufficiently strong to prevent a scaling of @xmath241 with @xmath101 alone . however , by reducing the eigenfrequencies @xmath242 selected for our three different @xmath45-values by the limiting values @xmath243 ( [ omcconv ] ) at the border of the absolutely unstable regime we effectively have eliminated the @xmath45-dependence and all gle data ( halftone symbols in fig . [ scaledom ] ) fall onto one curve . a similar scaling holds for the bulk wave number @xmath180 divided by @xmath244 ( [ qcconv ] ) . remarkably enough , by reducing the nse frequencies with the gle frequency @xmath245 ( [ omcconv ] ) the nse results ( open symbols in fig . [ scaledom ] ) almost show this one - variable scaling with @xmath101 . however , for the gle @xmath246 increases monotonously with the scaled group velocity @xmath101 whereas the nse results show a monotonous decrease with @xmath101 . this discrepancy between nse and gle results is caused by the different dispersion relations of the full hydrodynamic equations and the approximate gle cf . below . here we compare our numerical solutions of the nse with results from the gle and from experiments . first we discuss the selected wave numbers in the bulk region of pv flow . then in comparison with front propagation we show common selection properties of nse and gle . finally we compare with experiments . in fig . [ selectedwavelength ] we show all selected bulk wavelengths obtained from numerical simulations of the nse for bci ( open symbols ) and bcii ( filled symbols ) in comparison with results obtained numerically from the gle for bci ( halftone symbols ) . the nse wavelengths that are selected when the basic state is enforced at in- and outlet weakly decrease with increasing @xmath48 and @xmath45 . for the smallest @xmath248 their values are very close to the critical wavelength @xmath249 ( dotted line ) . for this boundary condition the wavelengths are mostly smaller than the critical one with a deviation of up to @xmath250 for the largest @xmath251 that was investigated here . these deviations are much stronger than the decrease of the critical wavelength with increasing reynolds numbers . it is interesting to note that transversal rayleigh - bnard convection rolls in horizontal shear flow @xcite show a qualitative and quantitative ( * ? ? ? * @xmath252 ) correspondence to pv flow . therefore , our results are not limited to pv flow in a taylor - couette apparatus only . in this context we also mention the experimental investigation of gu and fahidy @xcite . they observed that axial through - flow causes a rearrangement of the vortex centers similar to the one seen for tranverse convection rolls subject to a horizontal flow ( * ? ? ? * fig . 2 ) . without through - flow the vortices are aligned along a straight line roughly in the gap center . with increasing through - flow vortices are alternatingly displaced towards the outer or inner cylinder , thereby reducing the axial component of their distance and thus the wavelength . viewed in the @xmath253 plane with @xmath8 above @xmath7 , right ( left ) turning vortices for which @xmath107 is negative ( positive ) close to the inner cylinder are displaced towards the inner ( outer ) cylinder by a through - flow directed from left to right , since the through - flow enhances the axial flow component @xmath107 of a right turning vortex near the outer cylinder at @xmath8 , and weakens it near the inner one at @xmath7 and vice versa for the left turning one . obviously the wavelengths resulting for bci from the nse ( open symbols in fig . [ selectedwavelength ] ) differ substantially and systematically from those resulting from the gle ( halftone symbols ) : the former decrease with growing @xmath48 and @xmath45 while the latter increase . nevertheless we think cf . the discussion in sec . [ comparisonfront ] that the selection mechanism is quite similar . the nse wavelengths obtained for the ekman vortex generating bcii ( filled symbols in fig . [ selectedwavelength ] ) are similar to the bci results in the limiting cases of small @xmath48 or small @xmath45 , and near the border line @xmath146 of the absolutely unstable regime . in the vicinity of @xmath146 the stationary ekman vortices and the pv flow are spatially separated , and their interaction is very weak allowing for pv wavelengths like those for bci . for very small reynolds numbers the agreement in the pv wavelengths for bci and bcii is not yet understood . in between there is a visible difference of up to @xmath254 ( @xmath255 and @xmath256 ) between the bulk wavelengths obtained for the two boundary conditions . however , we found that the bulk phase velocities , @xmath257 , were almost independent of the boundary conditions : the relative difference of @xmath258 for bci and bcii is less than @xmath259 for the parameter regimes investigated here . furthermore , the deviation of @xmath258 from the critical value @xmath260 is less than about @xmath261 . hence , one can infer from the plots in fig . [ selectedwavelength ] for @xmath262 also the variation of the frequency eigenvalue with through - flow since @xmath263 for the largest @xmath251 we have observed for the ekman vortex generating bcii an interesting behavior for very small @xmath264 . for these parameters the pv pattern did not develop an axially homogeneous wavelength in the spatial region where the flow amplitude was indeed spatially uniform . under these circumstances the wavelengths roughly show a linear variation with @xmath1 between a larger value ( upper small filled triangles in fig . [ selectedwavelength ] ) at the upstream end of the bulk amplitude region and a smaller value ( lower small filled triangles in fig . [ selectedwavelength ] ) at the downstream end of the bulk region of constant flow amplitude . so the ekman vortex at the inlet inpedes the free downstream motion of the pv flow it exerts a phase pinning force on the pv pattern that stretches the node distances . the situation is somewhat similar to the explicitly phase pinning boundary conditions that have been investigated in rayleigh - bnard convection with through - flow @xcite . the selected wavelengths in the bulk region are practically independent of the system length as long as a saturation of the taylor vortices takes place . to check this we performed a few simulations with aspect ratios @xmath265 ( @xmath266 , bci and bcii ) and @xmath267 ( @xmath268 , bci and bcii ) and compared with the results obtained for our standard length @xmath12 . the change in the selected wavelength or frequency is less than @xmath269 if the aspect ratio is halved to @xmath265 . in the system with length @xmath267 no bulk region can be observed , therefore the wavelength can not reach a constant value . the oscillation frequency of the flow pattern is always independent of the axial position and mainly unchanged ; the deviations are less than @xmath270 even for the very short system of @xmath267 . we have also investigated the dependence of nonlinear , saturated pv flow on the numerical discretization . these tests show that the nonlinear vortex structures are basically independent of the discretization provided it is not to coarse if one bases the comparison of bifurcated flow structures obtained with different discretizations on the relative control parameter @xmath99 that is influenced via @xmath100 by the discretization in question @xcite . let us first consider taylor vortices without through - flow . then the gle ( [ gle ] ) contains no imaginary coefficients @xmath114 and the first - order spatial derivative is absent since @xmath271 . in this case the gle yields for propagating fronts @xcite as well as for stationary patterns in finite systems @xcite the critical wave number , @xmath272 , all over the extension of the pattern the boundary condition @xmath273 enforces the collaps of the supercritical band of stable bulk wave numbers of _ nonlinear _ vortex patterns to @xmath274 . this _ nonlinearly _ selected wave number @xmath274 happens to be for @xmath42 the same as the wave number of maximal _ linear _ growth under a _ linear _ front whose spatiotemporal evolution is governed by the dispersion @xmath275 ( [ omqbulk ] ) of the _ linear _ gle . in the presence of through - flow , however , the wave number of maximal growth under the _ linear _ front e.g. @xmath214 ( [ qflin ] ) of the gle differs from the one in the _ nonlinear _ bulk far behind the front [ @xmath232 ( [ qbulkfront ] ) ] . now , already without through - flow the dispersion relation of the _ linear _ nse differs significantly from that of the gle so that the wave number of largest temporal growth under a _ linear _ nse front deviates from the gle result @xmath274 . as an aside we mention that a somewhat similar behavior has also been observed experimentally @xcite and numerically for taylor vortices @xcite or rayleigh - bnard convection rolls @xcite which , however , were located in the nonlinear part of propagating fronts . in this context it is useful to keep in mind that the wavelength profile @xmath134 of numerically obtained taylor vortex fronts @xcite shows an axial variation with a characteristic dip in the steepest region of the front similar to the one of the full line in fig . [ fouriermodesbsbc]b near @xmath276 . now let us consider the through - flow case . in fig . [ omvalues ] we compare the eigenfrequencies of the _ nonlinear _ nse ( open symbols ) for bci with those ( solid line ) that would be selected by a _ linear _ front that is stationary at the border of the absolutely unstable regime . to that end recktenwald and dressler @xcite have determined the dispersion relation @xmath277 of linear perturbations @xmath278}$ ] in the complex @xmath211-plane resulting from the nse with a shooting method as described in ref . @xcite . the solid line in fig . [ omvalues ] represents the frequency @xmath279 selected by the stationary front @xmath280 of the _ linear _ nse . again , as discussed for the gle in sec . [ patternselectiona ] 5 , this frequency is determined by the saddle @xmath281 of @xmath277 for which the temporal growth rate @xmath282 . this defines the boundary between absolute and convective instability . with increasing @xmath48 the eigenfrequency of the _ nonlinear _ nse approaches the frequency selected by the _ linear _ stationary front at the border of the absolutely unstable regime as indicated for the three @xmath45-values shown in fig . [ omvalues ] . the front frequencies for these @xmath45-values are marked by small open symbols on the curve @xmath283 to indicate that the eigenfrequencies of the nse in the absolutely unstable regime ( large open symbols in fig . [ omvalues ] ) do indeed end at the right positions on this curve . this nse behavior is very similar to the gle behavior ( halftone symbols and dashed line ) . note , however , that the linear dispersion relations of nse and gle are different : the front frequency @xmath284 ( solid line in fig . [ omvalues ] ) is positive and increases with through - flow while @xmath285 ( dashed line ) is negative and decreases with through - flow . this difference in the dispersion relations seems to be the major cause for the differences in the selected patterns . in early experiments by snyder @xcite or takeuchi and jankowski @xcite the distinction between absolute and convective instability was not yet established . pv patterns were observed with wavelengths below the critical one for reynolds numbers @xmath286 @xcite . however , a pattern selection was not reported . the wavelengths were seen to vary up to @xmath287 from run to run for the same control parameter combinations and in some cases @xmath254 over the spatial extension . furthermore , the vortex spacings did not change after the occurrence of pv flow when increasing the relative taylor number up to @xmath288 @xcite . takeuchi and jankowski @xcite obtained wavelengths below the critical one for example with a deviation of @xmath289 for @xmath290 that is in the same order of magnitude of our nse results in the absolute instability regime . the experimental results of tsameret and steinberg @xcite exhibit a unique selection , similar to the results presented here . their wavelengths @xcite are always less than the critical one for axial boundaries that enforce stationary ekman vortex flow . however , in contrast to our results they observed no @xmath45 dependence of the selected wavelengths but an re dependence that is much stronger than ours leading to a relative deviation from @xmath249 of up to @xmath291 at @xmath292 for @xmath293 @xcite . in addition their phase velocity of pv flow , @xmath294 @xcite , is much smaller than ours , which is close to the critical one . all wavelengths observed for through - flow rates above @xmath295 belong to noise sustained structures in the convectively unstable region @xcite , which leads to deviations from @xmath249 of about @xmath296 when one limits the comparison to the regime of absolute instability . since the @xmath45-values at which the measurements of @xcite were performed are not given we have estimated an @xmath45-value of @xmath297 based on the convective instability border at @xmath295 . for this @xmath45 the above mentioned @xmath296 deviation of @xmath140 from @xmath249 is an order of magnitude larger than our nse results or the results ( [ qcconv ] ) of the gle . on the other hand , the experimental wave number found in @xcite for a known , published @xmath298 and @xmath48 up to 4 can be compared directly with our results to check the predicted @xmath45 and @xmath48 dependence . in this case all experimental wavelengths @xcite decrease up to @xmath299 below the critical one at @xmath300 whereas we would expect from our simulations and from @xcite less than half the deviation from @xmath249 . we have investigated propagating vortex structures in an axial flow for different realistic axial boundary conditions in systems of finite length . within the subregion of absolute instabilty a unique pattern selection is observed . the selected pv flow structures are independent of parameter history , initial conditions , and system s length ( provide it is large enough to allow for a nonlinear , saturated , homogeneous bulk region ) . but they depend on the axial boundary conditions . for conditions enforcing the basic state at the boundaries as well as for conditions that enforce stationary ekman vortex flow near the boundaries the pv pattern is suppressed at the inlet and outlet of the annulus . then one observes a characteristic stationary axial intensity and wave number profile , whereas the oscillation frequency of the pattern is constant all over the system . the analysis of the appropriate ginzburg - landau equation for pv flow shows that the selected frequency of the pattern oscillation is the eigenvalue of a nonlinear eigenvalue problem for which the axial variation of the corresponding eigenfunction is smooth and as small as possible . the eigenfunction is the complex pattern amplitude that characterizes the intensity and wave number profiles of the pv structure . the gle intensity profiles agree well with those of the nse . however , there are characteristic differences in the selected frequencies and wave number profiles of the full nse and the gle approximation . they are identified to be mainly caused by the different dispersion relations of the equations . approaching the border between absolute and convective instability the eigenvalue problem becomes effectively linear and the pattern selection mechanism becomes that one of linear front propagation . m. c. cross and p. c. hohenberg , rev . phys . * 65 * , 851 ( 1993 ) . g. ahlers , d. s. cannell , m. a. dominguez - lerma , and r. heinrichs , physica d * 23 * , 202 ( 1986 ) . g. ahlers and d. s. cannell , phys . lett . * 50 * , 1583 ( 1983 ) . r. heinrichs , g. ahlers , and d. s. cannell , phys . lett . * 56 * , 1794 ( 1986 ) . m. lcke , m. mihelcic , b. kowalski , and k. wingerath , in _ the physics of struture formation _ , edited by w. gttinger and g. dangelmayr ( springer - 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couette system without axial through - flow see r. c. diprima and h. l. swinney , in _ hydrodynamic instabilities and transition to turbulence _ , edited by h. l. swinney and j. p. gollub ( springer , berlin , 1981 ) , p. 139 . s. goldstein , proc . cambridge philos . soc . * 33 * , 41 ( 1937 ) . r. j. cornish , proc . r. soc . london ser . a * 140 * , 227 ( 1933 ) ; a. fage , proc . r. soc . london ser . a * 165 * , 501 ( 1938 ) . s. chandrasekhar , proc . usa * 46 * , 141 ( 1960 ) ; proc . r. soc . london ser . a * 265 * , 188 ( 1962 ) ; r. c. diprima , j. fluid mech . * 9 * , 621 ( 1960 ) ; s. datta , j. fluid mech . * 21 * , 635 ( 1965 ) ; e. r. krueger and r. c. diprima , j. fluid mech . * 19 * , 528 ( 1964 ) ; t. h. hughes and w. h. reid , philos . r. soc . london ser . a * 263 * , 57 ( 1968 ) ; l. elliott , phys . fluids * 16 * , 577 ( 1973 ) ; m. a. hasoon and b. w. martin , proc . r. soc . london ser . a * 352 * , 351 ( 1977 ) . r. c. diprima and a. pridor , proc . r. soc . london ser . a * 366 * , 555 ( 1979 ) . k. bhler and f. polifke , in _ nonlinear evolution of spatio - temporal structures in dissipative continous systems _ , edited by f. busse and l. kramer ( plenum press , new york , 1990 ) , p. 21 ; k. w. schwarz , b. e. springett , and r. j. donnelly , j. fluid mech . * 20 * , 281 ( 1964 ) ; r. j. donnelly and d. fultz , proc . nat . acad . usa * 46 * , 1150 ( 1960 ) ; n. gravas and b. w. martin , j. fluid mech . * 86 * , 385 ( 1978 ) ; p. l. greaves , r. i. grosvenor , and b. w. martin , int . j. heat & fluid flow * 4 * , 187 ( 1983 ) ; d. a. simmers and j. e. r. coney , j. mech . * 21 * , 59 ( 1979 ) ; m. m. sorour and j. e. r. coney , j. mech . sci . * 21*,397 ( 1979 ) . k. kataoka , h. doi , t. hongo , and m. futagawa , chem . eng . of japan * 8 * , 472 ( 1975 ) ; s. chandrasekhar , _ hydrodynamic and hydromagnetic stablility _ ( dover publications , new york , 1961 ) . for a review see , e. g. , r. e. kelly , adv . * 31 * , 35 ( 1994 ) . a. recktenwald , _ diplom thesis _ , universitt des saarlandes , 1991 ( unpublished ) . r. heinrichs , d. s. cannell , g. ahlers , and m. jefferson , phys . fluids . * 31 * , 250 ( 1988 ) . m. lcke and d. roth , z. phys . b * 78 * , 147 ( 1990 ) . d. roth , m. lcke , m. kamps , and r. schmitz , in _ ordered and turbulent patterns in taylor couette flow _ , edited by d. andereck and f. hayot , vol . 297 of nato asi series b ( plenum , new york , 1992 ) , p. 59 . r. tagg , w. s. edwards , and h. swinney , phys . a * 42 * , 831 ( 1990 ) . b. s. ng and e. r. turner , proc . r. soc . london ser . a * 382 * , 83 ( 1982 ) . j. e. welch , f. h. harlow , j. p. shannon , and b. j. daly , los alamos scientific laboratory report of the university of california , report no . la-3425 , 1966 ( unpublished ) ; g. p. williams , j. fluid mech . * 37 * , 727 ( 1969 ) ; f. h. harlow and j. e. welch , phys . fluids * 8 * , 2183 ( 1965 ) . c. w. hirt , b. d. nichols , and n. c. romero , los alamos scientific laboratory report of the university of california , report no . la-5852 , 1975 ( unpublished ) ; j. a. viecelli , j. comput . * 8 * , 119 ( 1971 ) ; a. j. chorin , math . * 22 * , 745 ( 1968 ) . there is an entrance chamber designed such that the fluid enters the annulus with no azimuthal velocity and with a plug flow like profile of the axial velocity @xcite . thus , an ekman vortex is not induced near the inlet . the annular poiseuille flow develops faster than the circular couette flow @xcite . the development length towards the homogeneous base flow measured by babcock _ et al . _ @xcite is about @xmath301 for @xmath302 . k. n. astill , j. t. ganley , and b. w. martin , proc . r. soc . london ser . a * 307 * , 55 ( 1968 ) ; j. e. r. coney and d. a. simmers , j. mech . * 21 * , 19 ( 1979 ) ; b. w. martin and m. a. hasoon , j. mech . sci . * 18 * , 221 ( 1976 ) ; b. w. martin and a. payne , proc . r. soc . london ser . a * 328 * , 123 ( 1972 ) . a. davey , j. fluid mech . * 14 * , 336 ( 1962 ) . h. kuhlmann , d. roth , and m. lcke , phys . a * 39 * , 745 ( 1989 ) . g. pfister and i. rehberg , phys . lett . a * 83 * , 19 ( 1981 ) . m. c. cross , p. g. daniels , p. c. hohenberg , and e. d. siggia , j. fluid mech . * 127 * , 155 ( 1983 ) . k. nozaki and n. bekki , phys . lett . * 51 * , 2171 ( 1983 ) . w. van saarloos and p. c. hohenberg , physica d * 56 * , 303 ( 1992 ) . k. nozaki and n. bekki , j. phys . jpn * 53 * , 1581 ( 1984 ) . r. conte and m. musette , physica d * 69 * , 1 ( 1993 ) . a. pocheau , v. croquette , p. le gal , and c. poitou , europhys . lett . * 3 * , 915 ( 1987 ) . using discretizations of @xmath303 , @xmath82 , and @xmath304 lattice points per unit length we observe a systematic deviation in the selected wave numbers of the nonlinear pv patterns . for @xmath305 , @xmath306 and the boundary condition bcii ( sec . [ evbc ] ) the selected wavelength of the saturated pv flow is @xmath307 for @xmath308 , respectively . a coarser grid provides a smaller @xmath309 and a bigger @xmath140 which is in agreement with fig . [ selectedwavelength ] . in the case of bci ( sec . [ bsbc ] ) the coarser grid decreases the wavelength @xmath310 for @xmath308 at @xmath305 and @xmath311 also in agreement with fig . [ selectedwavelength ] . by using the relative control parameter @xmath44 ( 2.9a ) with the appropriate @xmath85 these systematic deviations practically disappear . g. dee and j. s. langer , phys . lett . * 50 * , 383 ( 1983 ) . m. niklas , _ ph . d. thesis _ , rwth aachen , 1988 ( unpublished ) . cccccc + & @xmath100 & @xmath50 & @xmath58 & @xmath57 & @xmath59 + @xmath312 & * 2420.23 * & * 3.1305 * & * 0.144 * & * 0.0762 * & * 8.06 * + @xmath313 & * 138.62 * & * 252.96 * & * -27.23 * & * -49.68 * & * -12.33 * + + & @xmath60 & @xmath51 & @xmath61 & @xmath62 & @xmath63 + @xmath314 & * 1.20 * & * 3.647 * & _ 1/138 _ & _ 1/40.7 _ & _ 1/287 _ + @xmath315 & & & _ -51.8 _ & _ 70.5 _ & _ -97.8 _ +

a unique pattern selection in the absolutely unstable regime of a driven , nonlinear , open - flow system is analyzed : the spatiotemporal structures of rotationally symmetric vortices that propagate downstream in the annulus of the rotating taylor - couette system due to an externally imposed axial through - flow are investigated for two different axial boundary conditions at the in- and outlet . detailed quantitative results for the oscillation frequency , the axial profile of the wave number , and the temporal fourier amplitudes of the propagating vortex patterns obtained by numerical simulations of the navier - stokes equations are compared with results of the appropriate ginzburg - landau amplitude equation approximation and also with experiments . unlike the stationary patterns in systems without through - flow the spatiotemporal structures of propagating vortices are independent of parameter history , initial conditions , and system s length . they do , however , depend on the axial boundary conditions in addition to the driving rate of the inner cylinder and the through - flow rate . our analysis of the amplitude equation shows that the pattern selection can be described by a nonlinear eigenvalue problem with the frequency being the eigenvalue . the complex amplitude being the corresponding eigenfunction describes the axial structure of intensity and wave number . small , but characteristic differences in the structural dynamics between the navier - stokes equations and the amplitude equation are mainly due to the different dispersion relations . approaching the border between absolute and convective instability the eigenvalue problem becomes effectively linear and the selection mechanism approaches that one of linear front propagation .

Cover of 'Horton and the Kwuggerbug and More Lost Stories' by Dr. Suess (Photo: Dr. Seuss Enterprises, L.P.) From the literary lost and found – like the ones in the back of elementary school classrooms – come four "new" illustrated stories by Dr. Seuss that will be published for the first time collected in a book. Horton and the Kwuggerbug and Other Lost Stories, to be released by Random House on Sept. 9, contains tales originally published in Redbook magazine between 1950 and 1955, then largely forgotten. Seuss, christened Theodor Seuss Geisel, died in 1991 at the age of 87. (He took on the Dr. title as a joke about the doctorate in literature he abandoned to spend more time doodling.) He wrote and illustrated 43 books for kids (The Cat in the Hat, Green Eggs and Ham) that changed the way we think about children's literature. He championed what he called "logical insanity," by imbedding morals into silly rhymes as he made learning to read fun. Seuss's ever-popular book for grads, Oh, the Places You'll Go!, was No. 3 on USA TODAY's Best-Selling Books list as recently as May 29. Full page from 'Horton and the Kwuggerbug' by Dr. Suess (Photo: TM & copyright © by Dr. Seuss Enterprises, L.P. 2014) Charles D. Cohen, a scholar and collector of all-things Seussian, tracked down copies of the magazines that published Seuss. "For the most part, those magazines were tossed out when the next month's issue arrived and the stories were largely forgotten," Cohen writes in an introduction to the new collection. He call the four stories "fresh encounters with old friends and familiar places." "Horton and the Kwuggerbug" stars Seuss' faithful elephant who confronts a crafty and manipulative insect. "Marco Comes Late" explains why Marco, the imaginative kid in Seuss's first kids' book, And To Think I Saw It on Mulberry Street (1937), is late for school. Full page from 'Marco Comes Late' by Dr. Suess. (Photo: TM & copyright © by Dr. Seuss Enterprises, L.P. 2014) "How Officer Pat Saved the Whole Town" is set on Mulberry Street and stars a vigilant police officer. "The Hoobub and the Grinch" features another Grinch - not the one who stole Christmas in Seuss's 1957 book - but one that similarly believes, as Cohen puts it, "that everyone is a mindless consumer who can be manipulated." (Seuss would know: he worked in advertising.) Cohen, 53, a dentist in South Deerfield, Mass. -- what would Seuss make of that? -- also wrote the introduction to an earlier collection of seven magazine stories: The Bippolo Seed and Other Lost Stories in 2011. Read or Share this story: http://usat.ly/1rFCMyQ ||||| Horton and the Kwuggerbug: And More Lost Stories Dr. Seuss. Random, $15 (56p) ISBN 978-0-385-38298-4 More By and About This Author Charles D. Cohen, the avid Seussian behind The Bippolo Seed and Other Lost Stories, presents another four little-known manuscripts by Theodor Seuss Geisel. In his introduction, Cohen contextualizes the tales, which were published in Redbook and never became full-fledged picture books. In the title tale, “Horton and the Kwuggerbug” (1951), an insect and “terrible fellow! That Kwuggerbug guy” fools gentle Horton into ferrying him across an alligator-infested river and up a mountain to a delicious, out-of-reach Beezlenut tree. “Marco Comes Late” (1950) reprises And to Think That I Saw It on Mulberry Street as Marco exaggerates his reasons for arriving late to school. Mulberry Street’s escalating formula likewise figures in “How Officer Pat Saved the Whole Town” (1950), about a policeman who anticipates trouble on a quiet day. The most interesting entry is a two-page fragment, “The Hoobub and the Grinch” (1955), in which a proto-Grinch character urges a gullible creature to pay 98¢ for some string. By no means gems, these archives suggest how Geisel tinkered with characters, developed his signature tetrameter, and commented on ethical issues, circa 1950. Ages 4–8. (Sept.) ||||| Format: Hardcover Verified Purchase "Horton and the Kwuggerbug and More Lost Stories" gives a new generation of readers some fresh, but classic, Dr. Seuss stories. Charles D. Cohen is to be congratulated for having the tenacity to find these "lost" four Seuss works. He should be lauded for his generosity in sharing the stories with Dr. Seuss fans - old and young. This volume contains four stories; each one features a familiar character that appeared in other Seuss classics. Once again, the 100% faithful Horton the Elephant meets a less ethical critter - the Kwuggerbug - who imposes on Horton's good nature. Once again, Horton prevails. The imaginative Marco - "To Think That I Saw It on Mulberry Street - creatively parses words to explain his tardy arrival at school. Marco is definitely a politician in the making. Officer Pat, a less familiar Seuss character, saves the town from disaster - or what he thinks may be a disaster - in a series of hilarious actions. Finally, the Grinch - before he stole Christmas - cleverly markets a piece of green string to the Hoobub. The stories in "Horton and the Kwuggerbug and More Lost Stories" are all imaginative, absurd enough to delight children and adults, alike, and wonderful to read alone or to someone you love. Each story, whether rhymed or written in prose form, has a moral or lesson to be learned. Dr. Seuss' ability to create words and imbue characters with so much personality they cannot be forgotten shines through every tale. The rhymed stories flow smoothly and are easy to read aloud. Even when Dr. Seuss creates new words so that a rhyme is possible, the words seem to make sense and to be "real" words. Whether you are adding a new book to your own library or helping a child you love grow their own book collection, "Horton and the Kwuggerbug and More Lost Stories" is one book that must be included. Five stars!

– Horton heard a Who—and his ears might be ringing right now with the news that he's about to make a comeback. Random House is republishing four Dr. Seuss stories on Sept. 9 that haven't been seen since the 1950s, when they first made their appearance in Redbook magazine, reports USA Today. A Massachusetts collector who previously helped the book publisher exhume other long-forgotten Seuss tales is also the source of this new collection, entitled Horton and the Kwuggerbug and More Lost Stories. The new tongue-twisting tales by Theodor Seuss Geisel, who died in 1991, feature our old friend Horton; an appearance by Marco, the subject of Seuss' first children's book, And to Think I Saw It on Mulberry Street; and a slightly different Grinch than Whoville's villain—though this one also thinks that "that everyone is a mindless consumer who can be manipulated," according to collector Charles Cohen via USA Today. "For the most part, those [Redbook] magazines were tossed out … and the stories were largely forgotten," Cohen adds. A review in Publishers Weekly says the stories may not be "gems," but they do show Geisel honing his craft and characters.

Hit enter to search or ESC to close ||||| Image copyright OCEARCH / ROBERT SNOW Image caption Lydia was satellite-tagged off the coast of Florida last year, allowing scientists to track her movements The first great white shark seen to cross from one side of the Atlantic to the other may be pregnant, says the head of the expedition tracking her. At the weekend, the satellite-tagged fish, called Lydia, crossed the Mid-Atlantic Ridge, which marks a rough boundary line between east and west. She has now turned towards the UK, but it is unclear where she will go next. Chris Fischer told the BBC he thought she was pregnant and heading for birthing grounds in the Mediterranean. Mr Fischer, who is expedition leader and founding chairman of the Ocearch shark tagging venture, said that if Lydia continued on to Europe or Africa, she was likely to become "more coastal". If we're going to look after some of these magnificent apex predators - the lions of the oceans - we're all going to have to work together. No one country can do it Chris Fischer, Founding chairman, Ocearch He told BBC News: "I certainly think that it's possible for Lydia to make it to the UK." But he said that he could not know if that was where she was heading. Mr Fischer said there had been sightings of great white sharks in UK waters before, but added: "I think these were anecdotal versus a documented presence. So hopefully we'll be able to help with that." On Sunday (GMT) , Ocearch announced that Lydia had crossed the ridge into the eastern Atlantic. And although it is often argued that the waters of these isles are too cold for the sharks, Mr Fischer cast doubt on this. "One thing we have learnt just in the last year with sharks in the Atlantic is what we used to think was too cold simply is not," he said. "Lydia has come over from Nova Scotia [in eastern Canada]... These sharks have the capacity to deal with very cold water temperatures for long periods." But he said: "If I had to guess, I would guess that Lydia is pregnant, and that she has been out in the open ocean gestating her babies, and that this spring she will lead us to where those baby white sharks are born - the nursery." Mr Fischer, who has led numerous ocean expeditions, added: "If you forced me to guess where that was, I'd say it was over in the Mediterranean, near Turkey... but that's longball I'm playing. She could turn around right now and head back to Florida." Image copyright OCEARCH / ROBERT SNOW Image caption Chris Fischer described Lydia as "super-healthy" and reproductively mature He said that small white sharks had been observed in the Aegean Sea before, but scientists working on the team did not share his view. This was because preliminary analysis of blood samples from Lydia suggested she was not pregnant at the time of her tagging. But Mr Fischer defended his theory, saying there were still uncertainties over the way that white sharks become pregnant, adding: "The sperm from the male comes in a packet with a shell on it. They can carry it around for a while until a special organ inside them breaks down the shell and they get pregnant. "We know it's 18 months from when we discover the breeding aggregation to when they lead us to the nursery... What we don't know is how long do they carry that sperm packet and how long is it until their body breaks down the shell." Media playback is unsupported on your device Media caption Marine biologist Dr Gregory Skomal tells 5 live: "We're as surprised as anyone" Lydia is now roughly 1,600km (1,000 miles) from the western coasts of Ireland and Britain, and nearly 4,800km from Jacksonville, Florida, where the tracking device was attached to her in March last year. The young female shark has travelled more than 30,500km since last year. The Ocearch project was initiated to gather data on the movements, biology and health of sharks for conservation purposes as well as for public safety and education. The scientists have been using a custom-built 34,000kg (75,000lb) capacity hydraulic platform, operated from their research vessel the M/V Ocearch, to safely lift mature sharks so that researchers can tag and study them. Image copyright OCEARCH Image caption Rizzilient's satellite tag now shows a location on land, in northern Portugal Lydia was on the platform for 15 minutes, during which researchers extracted blood for analysis and performed an ultrasound examination, in addition to attaching the tag. Mr Fischer described Lydia as "super-healthy" at the time of her tagging. "I would say she's just been sexually mature for a short period of time, which would put her in her 20s," he said. "She looked like she had a bright future ahead of her - but I never would have dreamed she would lead us over to your neighbourhood. "It just shows that if we're going to look after some of these magnificent apex predators - the lions of the oceans - we're all going to have to work together. No one country can do it." Indeed, the threats currently facing shark species were illustrated when one of Ocearch's tagged animals - a 5ft-long female mako shark called Rizzilient - was apparently caught by commercial fishermen. The most recent fix for Rizzilient's satellite tag shows her on land, in the coastal city of Povoa de Varzim in northern Portugal. Millions of sharks die each year as by-catch or through targeted hunting to remove their fins, which are highly prized in parts of Asia for use in shark fin soup and as traditional cures. The Ocearch project has now tagged nearly 150 sharks, including not just great whites, but mako, hammerhead, tiger sharks and other species. Mr Fischer said one of the project's aims was to move away from the often competitive nature of academic research where data is proprietary. "One of the things we wanted to do [with Ocearch] is disrupt the whole way research like this normally works," he said. "The data is totally open-source, this is multi-institution and multidiscipline." He added: "The great thing about this is that the whole world gets to watch... people feel inspired when they're part of something." [email protected] and follow me on Twitter ||||| Is Lydia the great white shark PREGNANT? Tagged fish may be looking for a 'nursery' in the Mediterranean On Friday, Lydia was spotted 1,000 miles from Cornwall and Ireland The satellite-tagged 15ft, 2,000lb great white is around 800 miles away after she crossed the Mid-Atlantic ridge found in the middle of the ocean Today GPS tag showed she is heading west, but experts think the shark is looking for a nursery in the Mediterranean where she can raise some pups Great white sharks typically give birth to between two and 12 pups Lydia became the first tagged great white to cross the Mid-Atlantic Ridge No one understands why she is taking such a strange route as great whites are usually found in warmer waters A great white shark heading for British waters could be bringing some smaller ferocious fish with her, scientists have revealed. The deadly predator – named Lydia – became the first tagged great white shark to cross the Mid-Atlantic Ridge and scientists charting her progress have now revealed that the 15ft shark might be swimming towards Europe to give birth to pups. She is just 800 miles (1,255km) off the coast of Cornwall and Ireland in the Atlantic Ocean and has now turned away from the UK. Scroll down for video The great white sharked named Lydia has travelled 313 miles in the past 72 hours. She is currently headed west (pictured) But experts believe the shark is pregnant and in search of a nursery for her pups and could be en route to the Mediterranean HOW DO SHARKS GIVE BIRTH? Very little is known about the reproduction of great white sharks. Great white sharks are thought to reach sexual maturity aged around 15. The oldest female ever recorded was 40 years old. The predators are ovoviviparous which means that eggs develop and hatch in the uterus and continue to develop until birth. The great white shark has an 11 month gestation period and the pups' jaws start to form at one month. Unborn sharks feed on ova produced by the mother and are born in spring and summer. Mother sharks typically give birth to between two and 12 pups. But experts think she may be aiming for Turkey in search of a nursery in the long-run. Lydia, who weighs 2,000lb (907kg) has covered more than 19,400 miles in the past year since being fitted with a tracking device. She is being tracked as part of a ground-breaking marine life study by Osearch that aims to learn more about sharks' movements. Scientists have been following the ferocious fish for over a year and her progress can be followed on the project’s website. ‘Lydia pinged in this morning headed NW!’ researchers tweeted this morning. Experts say they are shocked by Lydia’s recent dash towards Europe and she has travelled 313 miles in the past 72 hours. Chris Fischer, expedition leader and founding chairman of the Ocearch shark tagging project, said Lydia may be looking for somewhere to rear young. He said: ‘I would guess that Lydia is pregnant and that she has been out in the open ocean gestating her babies and that this spring she will lead us to where those baby white sharks are born - the nursery.’ He thinks her chosen location may end up being off the coast of Turkey. Record breaker: The deadly predator has become the first tagged shark of its species to cross the Mid Atlantic Ridge, an enormous underwater mountain range under the ocean. She is currently swimming to the west (pictured) Deadly cargo: Tagging the shark (pictured) was a feat in itself, with heavy machinery used to hoist Lydia from the water in order to fit the tracking device WHAT IS THE MID-ATLANTIC RIDGE? The Mid-Atlantic Ridge (MAR) is a ridge found along the floor of the Atlantic Ocean. This rift marks the actual boundary between adjacent tectonic plates, where magma from the mantle reaches the seafloor, erupting as lava and producing new crustal material for the plates. It forms part of the longest mountain range in the world and separates the Eurasian Plate and North American Plate in the North Atlantic, and the African Plate from the South American Plate in the South Atlantic. Great White Sharks normally give birth to between two and 12 pups at a time after a gestation period of 11 months. Blood samples didn't show Lydia was pregnant when researchers used a 34,000kg hydraulic platform to hoist her from the water to fit her tracking device. But Mr Fischer, who has led numerous ocean expeditions, said there is uncertainty over how exactly Great Whites reproduce. ‘The sperm from the male comes in a packet with a shell on it. They [the female sharks] can carry it around for a while until a special organ inside them breaks down the shell and they get pregnant. ‘We know its 18 months from when we discover the breeding aggregation to when they lead us to the nursery. ‘What we don't know is how long they carry that sperm packet and how long is it until their body breaks down the shell.’ Lydia had been heading north but made a sharp turn back towards the U.S. Ladbrokes bookkeepers revealed odds of 2-1 for Lydia visiting Cornwall as her first port of call. Lydia has become the first tagged great white to cross the Mid Atlantic Ridge (pictured) - an underwater mountain range which separates the Eurasian and North American Plates - at around 10am on March 9 Her GPS tag only gives off a signal when she's near the water's surface so scientists sometimes have to wait days between new readings. Mr Fischer said it was impossible to predict where she'll head next. He said: ‘If you forced me to guess where that was, I'd say it was over in the Mediterranean, near Turkey - but that's long-ball I'm playing. ‘She could turn around right now and head back to Florida.’ She became the first tagged great white to cross the Mid-Atlantic Ridge - an underwater mountain range which separates the Eurasian and North American tectonic plates - on the morning of March 9. Great whites are traditionally tracked off the coasts of South Africa, Australia, New Zealand, the west coast of America from California up to Alaska, the Gulf coast and Hawaii. Shark biologist Ian Fergusson tweeted: ‘WhiteShark Lydia pinged in on the other side of MidAtlanticRidge! Welcome to the history books, #Lydia,’ while Chris Fischer, who is involved in the project, tweeted: '#Lydia turns E toward #UK continuing first doc Trans/Atl migration n hist!’ Lydia was tagged by the Ocearch project, which aims to monitor sharks to learn more about their movements Dr Gregory Skomal, 52, senior fisheries biologist with Massachusetts Marine Fisheries, said: ‘I have no idea what to expect from her next. I've been working with sharks for a very long time now and I have never seen anything like this.' ‘It's anyone's guess where she is going to go next but she has been heading east so she might continue to do so.’ ‘She's just short of 800 miles away from your coast now but in the grand scheme of things that really isn't far for her. It's all very exciting. ‘It's hard to say how long it might take her to get there. If she decides she wants to get to England she could get there in days. ‘Having said that, she is quite likely to meander. It could take her days, it could take her months, or it might not happen at all. ‘I think it would be great to see her turn up in the UK though.’ Though Lydia's journey is impressive, great whites are known for their marathon migrations. In 2003 a great white nicknamed Nicole travelled from South Africa to Australia and back - some 12,400 miles. In recent years there have been several sightings of Great whites off the coast of Britain. In September last year, fisherman David Bond said he had spotted a 14ft beast swimming close to his boat off the coast of Looe in southern Cornwall. The suspected sighting came just a day after a fisherman on board a lobster boat said he spotted a 'giant shark' get close to his vessel. All those who witnessed the shark dismissed the idea it could be a basking shark, saying the creature was much larger, prompting experts to consider the possibility it was a great white.

– A great white named Lydia recently made shark history: This weekend, she became the first of her kind known to have crossed from the western to the eastern Atlantic. That happened when she crossed a boundary known as the Mid-Atlantic Ridge. Days later, she's already making more headlines. Researcher Chris Fischer tells the BBC she may be pregnant and headed toward the Mediterranean to have her babies. Right now, she's about 800 miles from the British Isles, the Daily Mail reports. If she continues in that direction, she could be the first great white officially spotted in the country, Fischer believes. The 2,000-pound, 15-foot creature was tagged a year ago in Jacksonville, Florida, and she's swum more than 19,400 miles since. When she was tagged, she was "super healthy"; Fischer guesses that age-wise, she's in her 20s. You can follow her here.

the euclidean 3-sphere @xmath0 admits compact embedded minimal surfaces of any genus @xcite . for simple examples like a great 2-sphere or the ( minimal ) clifford torus there is a smooth deformation through constant mean curvature ( ) surfaces with the same topology , which can be expressed in terms of changing radii . for other minimal tori , as well as higher genus compact embedded minimal surfaces in @xmath0 it might be useful to have a general deformation technique . we do this for the case of tori , and present a smooth topology preserving deformation for tori in @xmath0 in theorem [ th : nocommon ] . by this theorem the moduli space of tori in @xmath0 is locally one dimensional . to get an idea of the global structure of the moduli space we turn to equivariant tori in @xmath0 @xcite , which are either flat or a truncation of some member of an associated family of a delaunay surface @xcite . we show that the moduli of equivariant tori in @xmath0 is a connected infinite graph whose edges are parameterized by the mean curvature , and by flowing through this moduli space of equivariant tori we classify the minimal , the embedded , and the alexandrov embedded tori therein . amongst harmonic maps @xcite there is an important class consisting of harmonic maps of finite type @xcite . to a harmonic map of finite type there corresponds an associated algebraic curve whose compactification is called the spectral curve . the genus of the curve is called the spectral genus , and denoted by @xmath1 . the crucial fact that makes it possible to adapt the whitham deformation technique @xcite to the case of tori in @xmath0 , is that a torus in @xmath0 always has finite spectral genus @xcite . the spectral curve of a torus is a double cover of the riemann sphere with @xmath2 many branch points . during the deformation the spectral curve changes such that two branch points remain fixed , while the other @xmath3 branch points may move around . the closing conditions involve a choice of two double points on the real part of the spectral curve : we call these the sympoints , and to ensure that the topology of the surface stays intact during the deformation , the flow of the sympoints has to be controlled . in the smooth deformation family of the clifford torus there is a @xmath4-family which allow a deformation into absolute cohomogeneity one rotational embedded tori . such a deformation is possible when in addition to the two sympoints there is a further double point on the real part of the spectral curve . by opening up this additional double point and moving the resulting two branch points off the real part , the spectral curve becomes a double cover of the riemann sphere branched now at four points : it has spectral genus @xmath5 and is the spectral curve of a delaunay surface , and the corresponding torus is a truncation of a delaunay surface in @xmath0 . we show that at the end of the flow the new branch points pair - wise coalesce with the two fixed branch points . hence in the limit the coalescing pairs of branch points disappear , and the limit curve is an unbranched double cover of the sphere : the spectral curve of a bouquet of spheres . in the rotational case , see also @xcite , our deformation corresponds to pinching the neck of a delaunay surface , starting at a flat torus and continuing through to a bouquet of spheres . thus the connected component of the clifford torus is an infinite comb : the spine ( @xmath6 ) consists of embedded flat tori parameterized by the mean curvature , and each tooth ( @xmath5 ) of embedded delaunay tori ends in a bouquet of spheres . by considering covers of clifford tori the moduli space of rotational tori is a @xmath7family of such combs . it turns out that each bouquet of spheres occurs exactly twice in this moduli space ( theorem [ thm : sphere - bouquet ] ) , so that we may glue the two families together there . thus the moduli space of rotational tori in @xmath0 is an infinite connected graph . a similar picture transpires in the non - rotational case . in each isogeny class there is a sequence of @xmath6 tori that can be deformed into @xmath5 tori . in the non - rotational case a @xmath5 deformation family stays away from bouquets of spheres , and we prove that every @xmath5 deformation family begins and ends at a @xmath6 torus ( theorem [ thm : moduli - space ] ) . the above results combined give that every deformation family of absolute cohomogeneity one tori ends at a flat torus . the classification of absolute cohomogeneity one tori is thus reduced to that of spectral curves of flat tori with a double point on the real part ; this initial data is classified and interpreted geometrically . we classify the equivariant minimal tori , as well as the embedded and alexandrov embedded equivariant tori , and prove that the minimal clifford torus is the only embedded minimal equivariant torus in the 3-sphere . we also show that the spectral curve of an equivariant torus has no double points off the real part ( theorem [ th : no_equi_bub ] ) , which implies that there can not be a bianchi - bcklund transform of an equivariant torus into a torus . we conclude the paper by proving that the moduli space of equivariant tori in @xmath0 is connected . throughout the text we provide graphics of some of the surfaces under discussion . more images and videos of deformation families can be viewed at the website @xcite . we start by recalling the description of tori in terms of spectral curves and abelian differentials @xcite . we then adapt a deformation technique from @xcite and prove that any generic torus in @xmath0 lies in a smooth family of tori in @xmath0 . let @xmath8 be a hyperelliptic riemann surface with meromorphic function @xmath9 of degree two and with branch points over @xmath10 and @xmath11 . then @xmath8 is the _ spectral curve _ of an immersed torus in @xmath12 if and only if the following four conditions hold : 1 . besides the hyperelliptic involution @xmath13 , the surface @xmath8 has two further anti - holomorphic involutions @xmath14 and @xmath15 , such that @xmath14 has no fix points and @xmath16 . 2 . there exist two non - zero holomorphic functions @xmath17 on @xmath18 such that for @xmath19 @xmath20 3 . the forms @xmath21 are meromorphic differentials of the second kind with double poles at @xmath22 . the singular parts at @xmath23 respectively @xmath24 of these two differentials are linearly independent . 4 . there are four fixed points @xmath25 of @xmath26 , such that the functions @xmath27 and @xmath28 are either @xmath29 or @xmath30 there . given the spectral curve of an immersed torus in @xmath12 , let @xmath31 denote the value @xmath32 , and @xmath33 the value @xmath34 at the four fixed points of @xmath26 where @xmath27 and @xmath28 are either @xmath29 or @xmath30 . we call @xmath35 and @xmath36 the sympoints . for @xmath37 , the mean curvature of the corresponding torus in terms of the sympoints is @xmath38 we shall describe spectral curves of tori in @xmath12 via hyperelliptic surfaces of the form @xmath39 where @xmath40 $ ] is a polynomial of degree @xmath1 and @xmath41 the involutions of the spectral curve are @xmath42 making use of a rotation of @xmath9 and a rescaling of @xmath43 we may assume that @xmath44 is a polynomial with highest coefficient one . the meromorphic differentials @xmath45 have the form @xmath46 with polynomials @xmath47 $ ] of degree @xmath48 and @xmath49 . we next describe a one parameter family of deformations of the spectral curve , that depends on a deformation parameter @xmath50 . we view all functions on the corresponding spectral curves as functions in the variables @xmath9 and @xmath50 . since the path integrals of the differentials @xmath21 along all cycles in @xmath51 are integer multiples of @xmath52 , these differentials do not depend on the deformation parameter @xmath50 . further , see @xcite ( ch.3 , prop . 1.10 ) , a meromorphic function @xmath53 on a hyperelliptic riemann surface given by @xmath54 is of the form @xmath55 with rational functions @xmath56 . hence both @xmath57 are global meromorphic functions on @xmath8 with only possible poles at the branch points of @xmath8 . more precisely these meromorphic functions are of the form @xmath58 with polynomials @xmath59 $ ] of degree @xmath48 and @xmath60 . integrability @xmath61 reads @xmath62 which yields @xmath63 here dash and dot denote the derivatives with respect to @xmath9 respectively @xmath50 . the differential @xmath64 is a meromorphic @xmath29-form on @xmath8 with only poles at most of order three at @xmath65 , and roots at the sym points @xmath66 . further , since @xmath67 , @xmath68 and @xmath69 , we conclude that @xmath70 with a real function @xmath71 . using and we obtain @xmath72 and combining the above gives @xmath73 to preserve the topology during the flow , the values of @xmath74 should be fixed at the two sym points @xmath75 and @xmath76 . consequently @xmath77 , which gives @xmath78 [ th : nocommon ] let @xmath8 be a genus @xmath1 spectral curve of a torus in @xmath0 . if the two differentials @xmath21 for @xmath19 have no common roots , then @xmath8 is contained in a unique smooth one dimensional family of spectral curves of tori in @xmath12 . if the roots of @xmath79 and @xmath80 are pairwise distinct , then the @xmath2 values of equation at these roots uniquely determine the values of @xmath81 and @xmath82 there . therefore the equation determines the polynomials @xmath81 and @xmath82 uniquely up to a real multiple of @xmath79 and @xmath80 . the choice @xmath83 and @xmath84 in and corresponds to a rotation of @xmath9 . for given @xmath81 and @xmath82 the equations determine uniquely the derivatives of all roots of the polynomials @xmath44 and @xmath85 . the condition @xmath86 together with the assumption that the highest ( and lowest ) coefficient of the polynomial @xmath44 has absolute value one determines the polynomial @xmath44 in terms of its roots up to multiplication with @xmath87 . we conclude that these conditions on @xmath44 determine @xmath88 , @xmath89 and @xmath90 in terms of @xmath81 and @xmath82 . we remark that due to equation the solutions @xmath88 of both equations coincide . finally the condition that the highest ( and lowest ) coefficient of @xmath44 is qual to one , fixes the rotations . therefore there exist unique solutions @xmath81 and @xmath82 of . we expect that one can pass through common zeroes of the @xmath91 , therefore making the deformation global , but this will be considered elsewhere . below we will restrict to the cases of spectral genera @xmath6 , where this is trivially true , and @xmath5 where the roots of @xmath79 and @xmath80 turn out to always be distinct throughout the flow ( corollary [ th : no_common_zeroes ] ) . the double cover of the isometry group of @xmath92 is @xmath93 via the action @xmath94 . a surface is _ equivariant _ if it is preserved set - wise by a one - parameter family of isometries . to an equivariant surface we associate two _ axes _ : these are geodesics which are fixed set - wise by the one - parameter family of isometries . an equivariant surface is rotational precisely when one of its axes is fixed point - wise . equivariant surfaces have spectral genus zero or one @xcite . by a theorem of docarmo and dajczer @xcite , an equivariant surface is a member of an associated family of a delaunay surface , so up to isometry determined by an elliptic modulus and its sympoints . hence an equivariant surface in the 3-sphere is parameterized by its elliptic modulus , its mean curvature , and its associated family parameter . we will express the differential equations and in terms of the three coordinates @xmath95 ^ 3\ ] ] where @xmath96 is the elliptic modulus , and @xmath97 are defined in terms of the sympoints as @xmath98 the mean curvature @xmath99 in can then be expressed as @xmath100 the following identities will be used below : @xmath101 the derivatives of @xmath97 with respect to the flow parameter are @xmath102 in the spectral genus zero case , @xmath103 , the spectral curve is @xmath104 , and the elliptic modulus @xmath105 . the functions @xmath85 in for @xmath19 are polynomial in @xmath9 of degree one , and from @xmath106 we conclude that @xmath107 for some smooth complex valued functions @xmath108 . thus @xmath45 integrates to @xmath109 and consequently the functions @xmath110 in are @xmath111 . we may fix one of the sympoints , and assume without loss of generality that @xmath112 during the flow . then @xmath113 , which is equivalent to @xmath114 , or equivalently @xmath115 . thus equation reads @xmath116 evaluating this at @xmath117 gives @xmath118 from we get @xmath119 set @xmath120 . then together with and the fact that @xmath121 when @xmath112 , the flow equations and reduce to the single equation @xmath122 . the solution to this equation is given by @xmath123 with some constant of integration @xmath124 . consequently , the argument of the sympoint @xmath125 = 2 \arccos(-\tanh(t))$ ] can vary over all of the interval @xmath126 , and is strictly monotonic . hence also the mean curvature @xmath99 by equation is strictly monotonic , and given by @xmath127 . in summary , we have proven the following [ th : cliff_fam ] every flat torus in the 3-sphere lies in a smooth @xmath128family of flat tori . each family is parameterized by the mean curvature . in the spectral genus one case , the meromorphic differentials @xmath45 are linear combinations of the derivative of a meromorphic function and an elliptic integral . we write these meromorphic differentials in terms of jacobi s elliptic functions . we define an elliptic curve by @xmath129 here @xmath130 $ ] is the real modulus . then @xmath131 and the only roots of @xmath132 are at @xmath133 . in addition to the three involutions in , the elliptic curve has a further holomorphic involution @xmath134 we decompose @xmath135 into the symmetric and skew symmetric part with respect to @xmath136 . the symmetric part is a real multiple of the single valued meromorphic function @xmath43 , and the skew symmetric part is a real multiple of a multi valued function @xmath137 with real periods . the first homology group of the elliptic curve is generated by a cycle around the two branch points at @xmath138 and the cycle @xmath139 . the first cycle is symmetric with respect to @xmath136 and the second skew symmetric . therefore the integral of @xmath140 along the first cycle vanishes . we assume that the integral of @xmath140 along the second cycle is equal to @xmath141 . together with the first order poles of @xmath137 at @xmath142 and the skew symmetry with respect to @xmath136 this normalization determines @xmath137 uniquely . further , since @xmath143 , we conclude that the functions @xmath74 are linear combinations of @xmath43 and @xmath137 , and given by @xmath144 we shall express @xmath137 as a linear combination of complete elliptic integrals of the first and second kind . first we shall relate the curve to the elliptic curve @xmath8 in legendre s form with elliptic modulus @xmath145 given by @xmath146 let @xmath147 and @xmath148 denote the complete integrals of the first and second kind @xmath149 since @xmath148 has first order poles at the two points over @xmath150 , these two points correspond to @xmath142 . the involution @xmath136 corresponds to @xmath151 . therefore we set @xmath152 the integrals of the meromorphic differentials @xmath45 along all cycles of @xmath8 are purely imaginary . define @xmath153 the cycle around the two branch points @xmath138 corresponds to the real period and the cycle @xmath154 to the imaginary period of jacobi s elliptic functions . the integral along the real period vanishes and due to legendre s relations @xcite the integral along the imaginary period is equal to @xmath141 . in summary , we have found a linear combination of elliptic integrals of the first and second kind which obeys the conditions that characterize @xmath137 . in terms of the complete elliptic integrals @xmath155 and @xmath156 and the functions @xmath9 and @xmath43 , and the formulas ( * ? ? ? * and 17.3.30 ) @xmath157 the differential @xmath140 in simplifies to @xmath158 [ th : alpha_less_beta ] the complete elliptic integrals @xmath159 and @xmath160 satisfy @xmath161 assume first that @xmath162 . since @xmath163 , we have that @xmath164 hence the function @xmath165 has a real root in @xmath166 , say at @xmath167 , and thus also at @xmath168 . then @xmath169 , and together with @xmath170 gives @xmath171 and @xmath172 . finally , from @xmath173 and @xmath174 ( 13.8.11 in @xcite ) , we obtain @xmath175 . for @xmath176 , the function @xmath165 has a pair of reciprocal real roots @xmath177 with @xmath178 , and analogous arguments prove the assertion in this case . [ th : no_common_zeroes ] the differentials @xmath132 and @xmath140 have no common zeroes . while @xmath132 in has only roots at @xmath133 , we saw in the proof of proposition [ th : alpha_less_beta ] that @xmath140 has only roots @xmath179 when @xmath162 , and @xmath180 when @xmath176 . [ thm : flow ] every spectral genus one torus in @xmath0 lies on an integral curve of the vector field @xmath181 the vector field @xmath182 is analytic on the set @xmath183 , and its zero set is @xmath184 . we shall calculate the differential equations and in terms of the coordinates . from we compute the derivative of @xmath43 with respect to @xmath50 , and obtain @xmath185 in agreement with the skew - symmetry of @xmath137 with respect to @xmath136 we set @xmath186 from we obtain @xmath187 and @xmath188 for @xmath189 . putting all this together , the differential @xmath190 reads @xmath191 note that while @xmath192 has simple poles at @xmath133 , but @xmath193 does not , we conclude that the numerator of @xmath192 must vanish at @xmath133 , giving @xmath194 the unique solution of equation can now be computed , and is given by @xmath195 since @xmath196 , the above imply that @xmath197 now setting @xmath198 gives @xmath199 as required . the deformation equations of the sympoints read @xmath200 multiplying the first equation by @xmath201 and the second equation by @xmath202 and subtracting gives @xmath203 using the above formulae as well as we obtain @xmath204 and putting these into gives the equations for @xmath205 and @xmath206 , and concludes the proof of . the elliptic integrals @xmath159 and @xmath160 are analytic on @xmath207 , and at @xmath208 equal to @xmath209 . therefore the right hand sides of extend analytically to @xmath207 . due to proposition [ th : alpha_less_beta ] , for @xmath210 we have @xmath211 by the properties of @xmath159 and @xmath160 the vector field @xmath182 is analytic in @xmath212 on @xmath213 and has simple zeros at @xmath214 . thus the vector field is analytic on @xmath215 . the zero set statement follows from the fact that on @xmath216 , the functions @xmath217 and @xmath218 have zeros only at @xmath219 , and @xmath220 holds only at @xmath221 . that @xmath219 is a simple root follows from the series expansions at @xmath221 ( similarly at @xmath222 ) , given by @xmath223 equivariant @xmath224 tori ( @xmath225 ) . by proposition [ th : minlobes ] , there are no twizzled tori with one or two major lobes . , title="fig:",width=204 ] equivariant @xmath224 tori ( @xmath225 ) . by proposition [ th : minlobes ] , there are no twizzled tori with one or two major lobes . , title="fig:",width=204 ] equivariant @xmath224 tori ( @xmath225 ) . by proposition [ th : minlobes ] , there are no twizzled tori with one or two major lobes . , title="fig:",width=204 ] the proof of the following proposition [ prop : torus - of - revolution ] is deferred to section [ sec : frame ] . [ prop : torus - of - revolution ] an equivariant torus in @xmath12 is rotational if and only if the sympoints are reciprocal . special values of @xmath226 and @xmath227 include @xmath228 by the deformation equations if @xmath229 , for some @xmath230 , then @xmath231 throughout the flow . hence rotational tori stay rotational during the flow . we begin the qualitative analysis of the flow by first considering equivariant tori which are not rotational ( @xmath232 ) : we call these _ twizzled _ tori . the tori of revolution ( @xmath233 ) are treated subsequently in proposition [ prop : moduli - tori - of - revolution ] . the flow will be investigated in the open solid cuboid @xmath234 due to @xmath235 is strictly monotonic on @xmath236 with the locally constant function @xmath237 . [ prop : levelset ] define the set @xmath238 1 . [ item : levelset1 ] then every integral curve in @xmath236 lies in @xmath239 for some @xmath240 . [ item : levelset2 ] the following uniform estimates hold on the integral curve through @xmath241 : @xmath242 3 . [ prop : dq - sign ] the function @xmath243 has at most one zero along any integral curve in @xmath236 . \(1 ) from we compute @xmath244 = 0 $ ] , where @xmath245 { : = } x \dot y- \dot x y$ ] is the wronskian with respect to the flow parameter @xmath50 . since @xmath246 and @xmath247 are strictly positive in @xmath236 , then every integral curve in @xmath236 lies in @xmath248 for some @xmath249 . in @xmath236 , we have @xmath250 , so @xmath240 . \(2 ) for @xmath251 the first inequality of follows from @xmath252 on each integral curve @xmath96 is either positive or negative . the second inequality follows from @xmath253 in fact , due to either @xmath254 or one of the functions @xmath255 and @xmath256 is increasing and the other one decreasing . furthermore , if at some point @xmath50 with @xmath257 one of these functions is increasing , it stays increasing for all @xmath258 , and if it is decreasing , it stays decreasing for all @xmath259 , since the derivative of these functions can change sign only at the maximal value @xmath29 . \(3 ) if @xmath260 for some value of the flow parameter @xmath261 , then due to and latexmath:[\[\operatorname{sign}({\operatorname{\mathrm{k}}}){\ddot{\operatorname{\mathrm{k}}}}= \operatorname{sign}({\operatorname{\mathrm{k } } } ) \tfrac{d}{dt}{\operatorname{\mathrm{k}}}({{\mathbf{e}}}'{\operatorname{\mathrm{q}}}-{\operatorname{\mathrm{k}}}{{\mathbf{k}}}'{\operatorname{\mathrm{h}}})= for @xmath261 . thus @xmath263 is increasing at each of its zeros , and hence can have at most one zero . the next result shows that one endpoint of each integral curve corresponds to a flat torus . [ prop : moduli - space ] every maximal integral curve of in @xmath236 is defined on a finite interval and passes from a point in @xmath264 to a point in @xmath265 with the same sign of @xmath212 . furthermore , the mean curvature @xmath266 is a diffeomorphism of the maximal interval of definition onto a finite interval . due to both functions @xmath226 and @xmath227 are strictly monotonic . since @xmath267 and @xmath268 have no roots in @xmath236 , the integral curve must hit the boundary of @xmath236 at the end points ( either infinite or finite ) of the maximal interval of definition . due to proposition [ prop : levelset ] , @xmath212 takes the same value @xmath87 at both endpoints and the vector field does not vanish there . hence the maximal interval of definition is finite . due to proposition [ prop : levelset ] ( 3 ) the sign of @xmath243 changes once and is proportional to @xmath269 at the end points . due to @xmath269 is strictly increasing and the first claim follows . since @xmath270 is strictly increasing on @xmath271 , the mean curvature is strictly monotonic , and by proposition [ prop : levelset ] it is bounded . the boundary @xmath272 consists of the three parts with @xmath208 or @xmath273 , @xmath274 and @xmath275 . the first set contains the flat tori and the bouquets of spheres , which we consider later . the third set corresponds to the infinite mean curvature limit , that is tori in @xmath276 . in this limit the two sympoints coalesce and the differentials @xmath45 have zeroes there . since @xmath277 and @xmath278 do not have common zeroes by corollary [ th : no_common_zeroes ] , there are no such examples with spectral genus zero or one . therefore we treat only @xmath279 and @xmath280 . by proposition [ prop : torus - of - revolution ] the tori of revolution appear in the two - dimensional boundary @xmath281 of the moduli space of equivariant surfaces in @xmath12 . since @xmath282 along @xmath283 , tori of revolution stay tori of revolution throughout the flow . the flow thus describes one parameter families of tori of revolution . later in theorem [ thm : rev - mean - curvature ] we describe the range of mean curvature for the families in the flow , and exhibit those that contain a minimal torus of revolution . a consequence of the next result is that spectral genus @xmath5 tori of revolution lie in 1-parameter families with one endpoint at a flat torus and the other endpoint at a sphere bouquet . in the process we also show that the mean curvature stays bounded during the flow . since we often need to evaluate the functions @xmath43 and @xmath137 at the two sympoints we set @xmath284 [ prop : moduli - tori - of - revolution ] on the integral curve of through @xmath285 with @xmath286 and @xmath287 the function @xmath288 is equal to @xmath289 and @xmath290 is bounded away from zero . the maximal interval of definition is of the form @xmath291 with @xmath292 the mean curvature @xmath293 is a diffeomorphism from @xmath291 onto a finite interval . by @xmath294 is constant throughout the flow . let @xmath295 for @xmath19 be the two sympoints . if @xmath296 is bounded away form zero , then @xmath297 is bounded away from zero . for @xmath298 the values of @xmath43 at the sympoints coincide . by we have that @xmath299 is constant throughout the flow . we claim that @xmath300.\ ] ] we will need to consider the two cases @xmath301 and @xmath302 separately . in the first case we use @xmath303 ( * ( 11 ) ) , proposition [ th : alpha_less_beta ] and to obtain @xmath304 when @xmath301 , then again by @xmath303 , proposition [ th : alpha_less_beta ] , and @xmath305 we get @xmath306 thus @xmath307 . due to and proposition [ th : alpha_less_beta ] , the differential @xmath140 has no root between @xmath308 and @xmath309 . therefore @xmath296 and @xmath290 are bounded away from zero . due to proposition [ th : alpha_less_beta ] , the function @xmath310 is strictly increasing for @xmath311 . therefore the maximal integral curve passes from @xmath273 to @xmath208 . the vector field is at the left end point of order @xmath312 and at the right end point not zero . therefore the maximal interval of definition has the form @xmath291 . since @xmath313 is strictly monotonic , and @xmath290 is bounded away from zero , the mean curvature is a diffeomorphism from @xmath291 onto a finite interval . a corollary of theorem [ th : no_equi_bub ] below is that equivariant tori can not be dressed to tori by simple factors @xcite . while there exist large families of cylinders which can be dressed to cylinders with bubbletons @xcite , it is still an open question raised by bobenko @xcite , whether there are tori with bubbletons . double point _ is a point on the spectral curve at which both logarithms @xmath27 and @xmath28 are unimodular , but the spectral curve is not branched . [ th : no_equi_bub ] the spectral curve of an equivariant torus has no double points in @xmath314 . at a double point both logarithms @xmath27 and @xmath28 are unimodular . therefore it suffices to prove that the set of all @xmath315 , where @xmath27 and @xmath28 are unimodular is the set @xmath316 . this set coincides with the subset of @xmath317 , such that @xmath318 and @xmath319 are real . due to and we have for @xmath320 $ ] : @xmath321 if and only if @xmath322\cup{\mathbb{r}}_-$ ] , and @xmath323 and @xmath324 if and only if @xmath325\cup[\operatorname{\mathrm{k}}^{-1},\,\infty)$ ] . for @xmath326 : @xmath321 if and only if @xmath327\cup{\mathbb{r}}_+$ ] ; @xmath323 and @xmath324 if and only if @xmath328\cup[\operatorname{\mathrm{k}},\,0]$ ] . with @xmath208 we cover the genus zero case . to obtain a more geometric description of the above deformation we compute the frames of the surfaces . we do this in a slightly broader context by studying equivariant maps @xmath329 with complex mean curvature as in @xcite . this generalized framework for complex equivariant surfaces is then applicable to not only immersions into 3-dimensional space forms , but also pseudospherical surfaces in @xmath276 , surfaces in minkowski space , and other integrable surfaces in many others spaces by performing an appropriate reduction . let @xmath330 be an open and simply - connected domain with complex coordinates @xmath331 , and define @xmath332 on @xmath29-forms on @xmath333 by @xmath334 , @xmath335 extended complex linearly . let @xmath336 be a cartan decomposition . for a @xmath29-form @xmath337 on @xmath333 , we will write @xmath338 where with @xmath339 and @xmath340 . if we equip the matrix lie algebra @xmath341 with a multiple of the killing form @xmath342 , then we may choose a basis @xmath343 for @xmath341 satisfying @xmath344 , @xmath345 and @xmath346 = e_2 $ ] , @xmath347 = e_0 $ ] and @xmath348 = e_1 $ ] , and set @xmath349 let @xmath350 be a conformal immersion such that for the smooth function @xmath351 we have @xmath352 and @xmath353 . the remaining invariants of @xmath53 are smooth functions @xmath354 such that @xmath355 , @xmath356 and @xmath357 , and the normal map is @xmath358 $ ] . further , there exists a unique pair of maps @xmath359 which frame @xmath53 in the sense that @xmath360 then @xmath361 and @xmath362 , are smooth @xmath29-forms on @xmath333 with values in @xmath341 given by @xmath363 integrability @xmath364=0 $ ] is equivalent to the gauss - codazzi equations [ eq : gauss - codazzi ] @xmath365 conversely , given smooth functions @xmath366 with @xmath367 non - vanishing , satisfying the integrability equations , a conformal immersion @xmath53 with these invariants can be recovered by integrating to obtain maps @xmath359 which are unique up to transforms @xmath368 , @xmath369 . by the form of @xmath370 , the maps @xmath371 and @xmath372 frame @xmath373 in the sense of , and @xmath53 has the specified invariants . the map @xmath53 is unique up to @xmath374 , @xmath369 . let us first introduce new coordinates @xmath375 on @xmath333 such that @xmath376 we say a smooth map @xmath377 is @xmath378-equivariant , or simply equivariant if it is of the form @xmath379 for some @xmath380 and smooth map @xmath381 . what characterizes an equivariant map is that @xmath382 is @xmath383-independent @xcite . we first compute the logarithmic derivative of an equivariant map , and then integrate this to obtain the equivariant map itself . [ thm : equivariant - frame ] ( 1 ) the @xmath383-independent solution @xmath384 to @xmath385 = 0 { \,\,,}\\ d\alpha_\mathfrak{p}&+ [ \alpha_\mathfrak{k}\wedge\alpha_\mathfrak{p } ] = 0 { \,\,,}\\ d(\ast\alpha_\mathfrak{p})&+ [ \alpha_\mathfrak{k}\wedge(\ast\alpha_\mathfrak{p } ) ] = 0 \end{split}\ ] ] are @xmath386 , where @xmath1 is a smooth @xmath383-independent map from @xmath333 into the lie group of @xmath387 , and @xmath388 , where @xmath389 with @xmath390 , and @xmath391 is defined by @xmath392 ( 2 ) a solution to @xmath393 is given by @xmath394 the second equation in is the derivative of the first , and eliminates spurious constant solutions which would appear if only the first equation were present . \(1 ) write @xmath395 for some functions @xmath396 and @xmath397 , and let @xmath398 . then @xmath399 , so the form @xmath400 is a multiple of @xmath401 . then @xmath402 for some function @xmath403 . let @xmath404 , so @xmath405 , where prime is differentiation with respect to @xmath406 . then there exist functions @xmath407 of @xmath406 such that @xmath408 . by a calculation , is equivalent to the second equation of , along with @xmath409 . hence @xmath337 is of the required form , and concludes the proof of ( 1 ) . to prove ( 2 ) , we have @xmath410 in , where @xmath411 and @xmath412 . to compute @xmath413 , we will first show that @xmath414 satisfies [ eq : finalframe - p ] @xmath415 we have @xmath416 and @xmath417 , @xmath418 , @xmath419 and thus @xmath420 , proving . now @xmath421 . with @xmath422 we have @xmath423 hence @xmath424 , proving . thus @xmath425 . [ sec : vacuum ] the vacuum is the case in which the function @xmath426 in is constant . by the second equation in , @xmath427 with @xmath428 . the potential for the vacuum is @xmath429 , where @xmath430 and @xmath431 . since @xmath432=0 $ ] , the extended frame of the vacuum is @xmath433 with eigenvalues @xmath434 where @xmath435 are determined by @xmath436 , @xmath437 , @xmath438 . this differs from the frame in theorem [ thm : equivariant - frame ] by left multiplication by a @xmath439-and @xmath440-independent element of @xmath441 . two views of an equivariant @xmath442 torus in @xmath0 . , title="fig:",width=308 ] two views of an equivariant @xmath442 torus in @xmath0 . , title="fig:",width=308 ] to describe equivariant immersions into @xmath443 we specialize the above formulas . we first make the reduction in that @xmath444 , which is equivalent to @xmath445 . given an extended frame @xmath446 and two distinct sympoints @xmath447 , then @xmath448 is a conformal immersion @xmath449 with constant mean curvature @xmath99 given in . for the translation @xmath450 we write @xmath451 . if @xmath452 is periodic with period @xmath453 , then we define the monodromy @xmath454 of @xmath455 with respect to @xmath453 as @xmath456 the closing condition @xmath457 with respect to a translation is equivalent to @xmath458 if @xmath27 and @xmath459 denote the eigenvalues of the monodromy , then reads @xmath460 , or equivalently that there exist four integers @xmath461 such that for @xmath462 we have @xmath463 the torus is embedded if and only if the _ winding numbers _ @xmath464 all have absolute value equal to one . integrating @xmath193 with @xmath465 yields an extended frame @xmath455 of a flat surface in @xmath0 . by theorem [ thm : equivariant - frame ] and example [ sec : vacuum ] , the extended frame of any flat surface ( up to isometry and conformal change of coordinates ) is @xmath466 then also ( up to isometry and conformal change of coordinates ) any flat immersion @xmath449 is of the form @xmath467 with extended frame @xmath455 as in and two distinct sympoints @xmath447 . the eigenvalues of @xmath455 are @xmath468 with @xmath469 define @xmath470 then by equation the immersion @xmath53 factors through the lattice @xmath471 if and only if @xmath472 the dual of a lattice @xmath473 in @xmath378 is the lattice @xmath474 . [ prop : flat - torus ] \(i ) a flat immersion @xmath475 with extended frame @xmath455 is closed with respect to a lattice @xmath476 if and only if @xmath477 , where @xmath478 and @xmath479 ( ii ) the torus is rectangular and embedded if and only if @xmath480 . \(iii ) every flat torus is isogenic to a rectangular embedded flat torus . \(i ) since @xmath481 the condition is equivalent to @xmath477 . \(ii ) the torus is embedded if and only if @xmath482 , and rectangular if and only if @xmath483 . the corresponding periods @xmath484 and @xmath485 are dual to @xmath486 and @xmath487 and generate @xmath488 . clearly @xmath489 , and consequently @xmath488 are rectangular , since @xmath490 . \(iii ) from ( i ) we know that a lattice @xmath473 of any torus is a sublattice of @xmath488 , which by ( ii ) is the lattice of the embedded rectangular torus . hence there is an isogeny taking @xmath488 to @xmath473 . [ th : clifford ] the lattice of an embedded flat torus is square if and only if it the mean curvature is zero . swapping the sympoints does not affect the period lattice of a flat torus . solving the four equations for the periods gives @xmath491 in particular , setting @xmath492 , a computation shows that the generators of a lattice of an embedded flat torus satisfy @xmath493 thus @xmath494 if and only if the mean curvature is zero . setting @xmath495 we obtain the generators @xmath496 and @xmath497 of the square lattice of the clifford torus . swapping the sympoints @xmath498 , results in the integers @xmath464 swapping second indices : @xmath499 . this does not change the periods @xmath500 in . consider the @xmath29-form @xmath501 , where @xmath502 are given in equation with @xmath43 as in for some @xmath503 and @xmath504 . integrating the @xmath29-form @xmath193 with these choices then yields an @xmath128-equivariant extended frame @xmath505 for smooth maps @xmath506 and @xmath507 . now let @xmath508 be two distinct sympoints . the immersion @xmath509 in is then a conformal equivariant immersion with mean curvature . equivariance reduces the gauss equation to @xmath510 . a solution to this equation is the _ square root of the conformal factor _ @xmath511 given by @xmath512 where @xmath513 is the jacobi elliptic function . all other solutions are of the form @xmath514 , @xmath515 . the function @xmath426 is even and has no zeros on @xmath128 . the range of @xmath426 is @xmath516 $ ] . the function satisfies @xmath517 and @xmath518 , and limits to @xmath519 and @xmath520 . the period of @xmath426 depends on the parameter @xmath521 and is equal to @xmath522 . now a straightforward calculation shows that the fundamental forms of such an equivariant conformal immersion are [ eq : cmc - equi - i - ii ] @xmath523 with @xmath99 as in and hopf differential @xmath524 with @xmath525 . a period of an equivariant extended frame is of the form @xmath526 where @xmath527 , @xmath528 , and @xmath529 is the period of @xmath426 . the monodromy with respect to such a period is @xmath530 the imaginary part of a frame period has to be a period of the square root of the conformal factor @xmath531 . since @xmath426 has period @xmath522 , the imaginary part of @xmath453 in has to be of the form @xmath532 for some @xmath533 . from the extended frame of an equivariant torus is of the form @xmath534 . the middle and right factor are periodic in @xmath406 and do not depend on @xmath383 . hence both these factors have trivial monodromy if @xmath535 , and the monodromy with respect to a translation by @xmath536 is @xmath537 clearly @xmath538 so it suffices to show that @xmath539 to conclude the proof . let @xmath540 , then a calculation yields @xmath541 since @xmath542 and @xmath543 are functions of @xmath426 , they are also periodic with period @xmath529 , so @xmath544 subtracting from and integrating over the interval @xmath545 $ ] gives @xmath546 further , since @xmath547 and @xmath548 it follows that @xmath549 . thus @xmath550 shares the properties of @xmath137 which determine it uniquely . hence @xmath539 . by we have @xmath551 , so translation by a period @xmath453 induces an ambient isometry . the _ equivariant action _ is the action of the 1-parameter group @xmath552 of isometries of @xmath0 defined by @xmath553 since @xmath554 the commutator of the equivariant action @xmath555 in the group @xmath556 of orientation preserving isometries of @xmath0 is a two - dimensional torus . with the exception of two geodesics the orbits of @xmath557 are two - dimensional embedded tori . these geodesics , which we call the _ axes _ of the surface , are linked , and are situated so that every geodesic 2-sphere through one is orthogonal to the other . every orbit of the equivariant action , with the exception of the two axes , is a @xmath558-torus knot in the corresponding orbit of @xmath557 , with @xmath559 if we identify @xmath560 then the equivariant action extends to an action on @xmath561 given by @xmath562 , called the _ extended action_. in particular , the translation @xmath563 by a period @xmath453 induces the ambient isometry @xmath564 with @xmath565 and @xmath566 . for a flat torus this can always be achieved since we have not used the freedom of the mbius transformation . a spectral genus one torus is a surface of revolution , if and only if the equivariant action is the rotation around a geodesic , or equivalently if fixes point wise one geodesic of @xmath0 . the generator of the extended action has eigenvalues @xmath567 . thus there exists a zero eigenvalue , if and only if @xmath568 , which is equivalent to @xmath569 . [ prop : closing - conditions ] a spectral genus one surface in @xmath0 is closed along two independent periods if and only if there exists a @xmath570 with @xmath571 for @xmath572 and @xmath573 . suppose we have two @xmath128-independent periods @xmath574 for some @xmath575 and @xmath576 , @xmath577 . let @xmath578 be the respective frame monodromies with eigenvalues @xmath579 . then there exist four further integers @xmath461 as in for @xmath462 . hence @xmath580 , and we write this system as @xmath581 hence @xmath582 is in @xmath583 and satisfies @xmath584 and @xmath585 . conversely suppose that there exists @xmath586 satisfying @xmath584 and @xmath585 . let @xmath587 be a basis for the lattice @xmath588 . then there exist @xmath589 and @xmath590 such that holds . then @xmath591 generate a lattice with respect to which the surface is doubly periodic . the closing conditions in proposition [ prop : closing - conditions ] can be used to describe the intersection of the zero sets of two functions on the parameter space @xmath592 . the curve forming the intersection of two level sets then integrates to the vector field . for @xmath593 as in proposition [ prop : closing - conditions ] , there exists @xmath594 such that @xmath595 and @xmath596 . the closing conditions are thus @xmath597 , where @xmath598 and @xmath599 . if we set @xmath600 , then the system of implicit flow equations is @xmath601 of which we next compute the matrix on the right hand side . up to scale , @xmath602 is a cross product of its rows . hence @xmath603 since @xmath604 , this matrix is a scalar multiple of @xmath605 hence @xmath606 is a scalar multiple of @xmath607 . the derivatives of @xmath43 and @xmath137 with respect to @xmath212 and @xmath608 , where @xmath609 were computed in , and . a calculation yields that @xmath607 is a scalar multiple of @xmath610 changing variables from @xmath611 to @xmath612 , and rescaling , yields . a sampling of @xmath613 tori of revolution in @xmath0 . , title="fig:",width=202 ] a sampling of @xmath613 tori of revolution in @xmath0 . , title="fig:",width=202 ] a sampling of @xmath613 tori of revolution in @xmath0 . , title="fig:",width=202 ] we next determine those flat tori which allow a bifurcation into genus @xmath5 tori . these are precisely those flat tori whose spectral curves have a double point on the unit circle . we will show in theorem [ thm : moduli - space ] that the spectral genus one tori lie in flow families which begin at a flat torus with a double point on @xmath154 . these flat tori hence serve as initial conditions for the spectral genus @xmath5 flow . the purpose of this section is to classify the flat tori in @xmath0 with a double point on @xmath154 . we will show that three integers determine a primitive flat torus with a double point on @xmath154 up to the @xmath154 action and complex conjugation on the spectral curve . this is done by parameterizing the configuration space of three marked points on @xmath154 as follows : let @xmath614 denote the union of all triples of unimodular numbers in which two of the three entries coincide . let @xmath615 , where we identify triples obtained by the three transformations : * rotation @xmath616 with @xmath617 . * inversion @xmath618 . * swapping of the sympoints @xmath619 . now we define a mapping @xmath620 [ thm : tau ] the map is bijective from @xmath621 onto @xmath622 . for @xmath623 choose square roots and set @xmath624 . then @xmath625 and @xmath626 , so @xmath627 is real . if @xmath628 , then @xmath629 is contained in the @xmath154 orbit of @xmath630 , and @xmath631 so @xmath632 . this shows @xmath633 , and @xmath634 . for the map @xmath635 defined by @xmath636 we have @xmath637 since each of the three squared factors is non - positive . furthermore , @xmath638 is equivalent to @xmath639 . hence we have @xmath640 . define * rotation @xmath641 with @xmath617 . * inversion @xmath642 . * swapping of the sympoints @xmath643 . * changing the signs of the entries of @xmath644 independently . the transformations ( a)-(b ) do not change @xmath634 , while ( c ) negates signs and swaps @xmath645 and @xmath646 , while ( d ) negates two signs in @xmath627 for each sign change . if @xmath647 for at least one @xmath648 then @xmath649 . hence if @xmath634 , then @xmath640 implies @xmath650 for all @xmath648 . then @xmath651 if and only if @xmath652 and @xmath653 . these are equivalent to @xmath654 where @xmath655 thus @xmath634 with @xmath640 determines the following elements of @xmath656 uniquely up to ( a ) and ( b ) : @xmath657 furthermore the numbers @xmath658 determine @xmath659 up to the transformations @xmath660 and @xmath661 . due to @xmath662 the condition @xmath640 is equivalent to @xmath663 . this shows that @xmath664 is surjective from @xmath665 onto @xmath666 , whose pre - images are uniquely determined up to ( a)-(c ) . the _ spectral data _ of a flat torus with a double point is a triple @xmath667 of values of the spectral parameter at the double point and the two sympoints . we identify triples obtained by the transformations ( a)-(c ) . hence the set of spectral data is isomorphic to @xmath668 . the _ turning number _ of a plane curve is the degree of its gauss map ; we take the turning number to be unsigned . total turning number _ of a collection of immersed curves is the sum of their turning numbers . for twizzled surfaces , a _ profile curve set _ of the surface with respect to one of its axes @xmath669 is constructed as follows : let @xmath670 be a geodesic 2-sphere containing @xmath669 . the axis @xmath669 divides @xmath670 into two hemispheres . then a profile curve set of the torus with respect to @xmath669 is the intersection of the surface with @xmath670 or with one of the hemispheres of @xmath670 . by the equivariant action , all profile curve sets associated with an axis are isometric . for surfaces of revolution , there is a profile curve set with respect to the axis which is not the revolution axis . the minimal @xmath671 and @xmath672 tori . stereographically projected from @xmath0 to @xmath673 . , title="fig:",width=308 ] the minimal @xmath671 and @xmath672 tori . stereographically projected from @xmath0 to @xmath673 . , title="fig:",width=308 ] [ thm : flat - torus - integers ] \(1 ) [ item : integer - inequality ] the set of spectral data of flat tori with a double point on @xmath154 up to transformations ( a)-(c ) is in one - to - one correspondence with integer triples @xmath674 ( 2 ) [ item : flat - torus - covering ] let @xmath675 be a @xmath676 flat torus . then @xmath675 covers its underlying flat embedded rectangular torus @xmath677 times . each profile curve set @xmath678 ( @xmath679 ) of @xmath675 has total turning number @xmath680 . the set is a union of @xmath681 coinciding circles , and each circle is wrapped @xmath682 times . \(3 ) [ item : flat - torus - rev ] the case @xmath683 occurs if and only if the torus is rotational . let @xmath684 be the square roots of spectral data of a flat torus , and assume the torus has period lattice @xmath685 . we can frame the torus by an extended frame , and then the logarithmic eigenvalues of the monodromy with respect to these periods are @xmath686 as in . then there exist six integers @xmath461 such that @xmath687 for @xmath577 and @xmath688 . as in proposition [ prop : flat - torus ] let @xmath689 , and @xmath690 the lattice of the underlying embedded rectangular torus with orthogonal basis @xmath691 . since @xmath692 , we can expand @xmath693 since @xmath694 , the determinant of the above change of basis is @xmath695 ( 1 ) define @xmath696 . by construction @xmath697 . a computation gives @xmath698 . note that @xmath699 , and is never zero , since @xmath500 are not collinear . from we additionally have that @xmath700 and @xmath701 . hence it follows that @xmath702 . there exists a unique representative @xmath703 of @xmath704 with @xmath705 . the corresponding numbers @xmath676 defined in then obey . we thus have a map from spectral data to integer triples obeying , and by proposition [ thm : tau ] this map is bijective . \(2 ) the vector @xmath706 determines a lattice @xmath707 defined by @xmath708 the lattice @xmath709 contains all the periods of the torus with respect to which the logarithmic eigenvalues of the monodromy do not change their values at the double point . the lattice @xmath709 does not change if @xmath627 is multiplied by some integer , or the sign of @xmath710 is changed . due to the integers @xmath627 are determined by @xmath676 up to transformations ( c ) and ( d ) . two co - linear @xmath627 correspond to the same lattice @xmath709 . switching the signs of @xmath710 does not change @xmath709 . therefore the lattices @xmath709 of the flat tori with triple @xmath676 satisfying are those @xmath709 with one of the following vectors @xmath627 given by @xmath711 the transformations ( c ) and ( d ) act on sublattices @xmath712 as follows : * @xmath713 , * @xmath714 . since @xmath715 the lattices corresponding to the four vectors @xmath627 in are respectively equal to @xmath716}= \{n_1\gamma_1^\ast+n_2\gamma_2^\ast\mid n_1{\ell_1}+n_2{\ell_2}\in{\ell_0}\,{\mathbb{z}}\,\}\,,\quad c''\;\gamma_{[{\ell_0},\,{\ell_1},\,{\ell_2}]}\,,\\ & d''\;\gamma_{[{\ell_0},\,{\ell_1},\,{\ell_2}]}\ , \quad \mbox { and } \quad d''\ ; c''\;\gamma_{[{\ell_0},\,{\ell_1},\,{\ell_2}]}\ , . \end{split}\ ] ] for flat tori the two - dimensional group @xmath717 acts on the torus . since the axes do not depend on the subgroup @xmath718 , the two subgroups corresponding to the rotations of the embedded torus act on a geodesic sphere containing one of the axes . hence the smallest periods in @xmath719 and @xmath720 represent components of the profile curve sets . these wrapping numbers are @xmath721 and @xmath722 . the number of components times these wrapping numbers is equal to @xmath723 . but @xmath724 by . hence the total turning number is equal to @xmath677 . moreover , the corresponding embedded torus is covered @xmath677 times . \(3 ) clearly @xmath683 holds if and only if @xmath725 . we may assume that @xmath726 and then by this holds if and only if @xmath569 . by proposition [ prop : torus - of - revolution ] we conclude that @xmath683 holds if and only if the torus is rotational . [ prop : involution ] the family of non - rotational spectral genus 1 tori starting at the @xmath676 flat torus ends at the @xmath727 flat torus . due to proposition [ prop : levelset ] the difference @xmath728 is uniformly bounded away from zero . after possibly swapping the sympoints we may assume @xmath729 during the flow . we remark that @xmath730 is constant throughout the flow . in particular , @xmath35 can not pass through @xmath731 and @xmath36 can not pass through @xmath732 . due to proposition [ prop : moduli - space ] the function @xmath269 changes the sign , and the flow passes through a root of this function . this implies that @xmath36 has to pass through @xmath733 . we want to describe how the final six integers in are related to the corresponding initial six integers . since @xmath137 is multi - valued on the fixed point set @xmath154 of @xmath26 , we cut this circle at @xmath734 . at the end points of the flow with @xmath735 this point is a double point . this is a good choice for the cut , since at the end points of the flow the sympoints can not sit there . the multi - valued function @xmath137 is single valued on @xmath736 . the difference between the two boundary values of @xmath137 on this interval is equal to @xmath737 due to legendre s relation @xcite . with @xmath580 with respect to the periods @xmath738 as in , the final and initial integers are related by @xmath739 we remark that due to our choice these integers change their values only , when @xmath36 passes through @xmath740 . now let @xmath741 and @xmath742 denote the values of @xmath743 at the sympoints . after possibly independent hyperelliptic involutions , we have @xmath744 in agreement with our choice of the sympoints . note that @xmath745 . since the integers change only , when @xmath36 passes through @xmath740 , we can calculate the change of the @xmath746 in terms of the change of the values of @xmath43 and @xmath137 at @xmath740 . at the beginning and end of the flow we have @xmath747 and @xmath748 . due to @xmath744 we have @xmath749 therefore the final values are @xmath750 in terms of the initial values . the inequality @xmath751 excludes the plus sign , and concludes the proof . in a few places we will need formulae for equivariant tori and their profile curves in terms of the extended frame . identifying the unit quaternions with @xmath752 , @xmath753 , @xmath754 , and identifying @xmath755 , a computation gives @xmath756 with @xmath136 , we have @xmath757 , @xmath758 , @xmath759 , @xmath760 . applying these symmetries to the formula for the immersion at @xmath761 shows the profile curve of an equivariant surface of revolution in @xmath12 is @xmath762 . more explicitly , @xmath763 the profile curves of the two five - lobed sphere bouquets @xmath764 and @xmath765 , stereographically projected to @xmath766 . the gray central circles are the axes of revolution . , height=188 ] for @xmath767 with @xmath768 and @xmath769 , the @xmath558 _ sphere bouquet _ is constructed as follows . with @xmath770 , let @xmath771 be the union of the @xmath772 circles through @xmath773 and @xmath774 perpendicular to @xmath154 ( @xmath775 ) . inverse stereographic projection of @xmath771 to a geodesic 2-sphere and revolution about the image of @xmath154 as axis produces the @xmath558 sphere bouquet , consisting of @xmath772 pairwise tangent spheres forming a necklace . since the radius of each circle is @xmath776 , the mean curvature of the @xmath558 sphere bouquet is @xmath777 . since the @xmath558 sphere bouquet is the same as the @xmath778 sphere bouquet , then for @xmath779 , the number of distinct sphere bouquets with @xmath772 spheres is half the number of generators of @xmath780 . the @xmath781 sphere bouquet is a special case because its two spheres coincide . in the rotational case we write @xmath782 for brevity . [ thm : sphere - bouquet ] the @xmath783 family of rotational tori converges to the @xmath783 sphere bouquet as @xmath784 . for rotational tori we have @xmath785 . by proposition [ prop : closing - conditions ] there exists @xmath703 that is perpendicular to @xmath786 and @xmath787 . then @xmath788 and @xmath789 . hence @xmath683 and @xmath790 . define @xmath791 by @xmath792 . the limiting profile curve as @xmath793 can be computed from the profile curve for tori of revolution @xmath794 in . let @xmath795 , @xmath796 vary with the flow parameter @xmath797 $ ] , and assume without loss of generality that @xmath798 . from @xmath799 we conclude that @xmath800 . with @xmath801 and @xmath802 we have @xmath803 since the integrand in @xmath550 goes to @xmath804 as @xmath793 , then @xmath805 . the limiting profile curve as @xmath793 is thus @xmath806 . since @xmath807 traces out a straight line segment in @xmath378 , then @xmath808 traces out a circle . the discrete rotational symmetry of @xmath453 implies that the limiting set as @xmath793 is a sphere bouquet . the limiting points are @xmath809 on @xmath154 . the angle between the radii is @xmath810 . hence the limiting curve is the @xmath811 sphere bouquet , which is the same as the @xmath783 sphere bouquet . note that in the case @xmath812 the circle is a geodesic . we bring together proposition [ prop : moduli - space ] , proposition [ prop : moduli - tori - of - revolution ] and proposition [ prop : involution ] in the following theorem . [ thm : moduli - space ] spectral genus 1 tori lie in 1-parameter families with monotonic mean curvature . the family starting at the @xmath676 flat torus ends at the @xmath727 flat torus . by propositions [ prop : moduli - space ] and [ prop : moduli - tori - of - revolution ] the mean curvature is monotonic . by proposition [ prop : moduli - space ] , every flow starts and ends at a flat torus with a double point on @xmath154 . the integers associated to these two flat tori endpoints are computed next . as shown in lemma [ thm : sphere - bouquet ] , the two flows ending at the @xmath813 and @xmath814 flat tori at @xmath815 start at the same sphere bouquet at @xmath816 . because only tori of revolution flow to sphere bouquets , we conclude that every sphere bouquet is the limit of these two flows and no others . while the flow is singular at @xmath816 , proposition [ prop : involution ] nevertheless holds for the family constructed by gluing these two families together along the sphere bouquet . every orbit of the equivariant action with the exception of the two axes is a @xmath817-torus knot in the corresponding orbit of @xmath557 . due to and this implies that the orbit of a point on @xmath676 torus is generically a torus knot in the corresponding orbit of @xmath557 . if a @xmath676 torus does not meet the axes , then the linking numbers of the @xmath552 orbit of a point on the torus and the two axes are @xmath818 . [ thm : symmetry ] with @xmath819 , the symmetry group of an @xmath676 cohomogeneity one torus is a semidirect product of @xmath820 and @xmath821 if it is twizzled , and a semidirect product of @xmath820 and @xmath822 if it is a torus of revolution . let @xmath823 with @xmath824 and @xmath825 , and let @xmath826 . we first show that @xmath827 . if @xmath828 , then since @xmath829 and @xmath830 , then @xmath831 . since @xmath824 , then @xmath832 . hence @xmath833 . thus @xmath772 divides every element of @xmath834 . since @xmath835 , by the euclidean algorithm , there exist @xmath836 such that @xmath837 . hence with @xmath838 , then @xmath839 . this shows that @xmath840 . hence @xmath841 . there exists a basis @xmath842 for the torus lattice so that @xmath843 and @xmath844 , where @xmath845 . then @xmath846 and @xmath847 for some @xmath848 . by , the first fundamental form is preserved if and only if @xmath426 is preserved . the symmetry group thus contains the three conformal automorphisms @xmath849 , @xmath850 and @xmath851 . for tori of revolution , the sympoints satisfy @xmath569 by proposition [ prop : torus - of - revolution ] . hence the coefficient @xmath852 of the hopf differential in is real . since the mean curvature @xmath99 is real , the second fundamental form is preserved under complex conjugation . hence in this case there is a further anti - conformal automorphism @xmath853 . the two lobe counts are the orders of the two orientation - preserving cyclic subgroups of the symmetry group which fix one or the other axis point wise . [ thm : profile - curve - symmetry ] the lobe counts of a twizzled @xmath676 torus are @xmath854 and @xmath855 , and for a rotational torus it is @xmath855 . let @xmath557 be the two - dimensional torus . let @xmath372 be a subgroup of the orientation preserving subgroup of the isometry group of the torus which fixes one axis of the equivariant action point wise . such groups are homeomorphic to @xmath856 , and thus closed . closed subgroups of @xmath856 are either finite or all of @xmath856 , and since we are not considering surfaces of revolution , the group @xmath372 is finite , and thus cyclic . let @xmath857 be a subgroup which fixes every orbit of the equivariant action set wise . we compute @xmath858 and @xmath859 . from the proof of proposition [ thm : symmetry ] we conclude that @xmath860 , since @xmath861 . now @xmath862 and @xmath863 , and @xmath864 is equal to @xmath865 , and generated by @xmath866 , the order coincides with the order of @xmath867 . hence @xmath868 . similarly for the other axis . this proves the claim for the twizzled case . for the rectangular case a similar argument holds , and concludes the proof . in view of proposition [ thm : profile - curve - symmetry ] we call @xmath854 and @xmath855 respectively the _ minor and major lobe counts_. the tori shown in figure [ fig : twizzled2 ] have major and minor lobe counts @xmath772 and @xmath29 respectively . by theorem [ thm : moduli - space ] and theorem [ thm : flat - torus - integers ] we have [ th : minlobes ] the major lobe count of a non - rotational spectral genus 1 torus is at least 3 , and that of a rotational spectral genus 1 torus of revolution is at least 2 . the discrepancy between the two endpoints of the @xmath5 flow in proposition [ prop : involution ] is associated to the fact that at two points during the flow , the corresponding torus intersects one and then the other of its axes . at each of these two tori , one of the torus knots degenerates to a circle . the combinatorics of the profile curve sets of equivariant tori are almost invariant during the flow : they are invariant on two disjoint intervals . when the torus intersects its axis , the connectivity and turning numbers of the profile curve set jumps as described in lemma [ thm : twizzled - profile - curve ] . this phenomenon is depicted in figure [ fig : profile - twizzled ] . [ thm : twizzled - profile - curve ] if a profile curve set is immersed then @xmath869 . the total turning number of each profile curve set of a non - flat twizzled @xmath676 torus is @xmath677 or @xmath870 . claim 1 : if a profile curve set is not immersed , then @xmath871 . to prove the claim , let @xmath53 be the immersion of the torus as in . writing @xmath872 , the two profile curve sets are defined implicitly by @xmath873 and @xmath874 respectively . the profile curves are singular wherever @xmath875 , @xmath876 and @xmath877 all vanish or @xmath878 , @xmath879 and @xmath880 all vanish . the function @xmath881 decouples into @xmath882 , where @xmath883 and @xmath884 and @xmath885 , and @xmath886 and @xmath887 . then @xmath888 for @xmath679 , since @xmath889 never vanishes , it follows that @xmath890 and @xmath891 vanish if and only if @xmath892 vanishes . the additional condition that @xmath893 vanishes is ignored ; it specifies for which values of @xmath383 , if any , the curve fails to be immersed . since @xmath894 and @xmath895 are unimodular and @xmath896 and @xmath746 are real , this occurs if @xmath897 and either @xmath898 or @xmath899 . we have @xmath900 the zero sets of each of these expressions is the zero set of @xmath901 . at the zeros of @xmath901 , @xmath902 or @xmath903 . a computation shows that the zero set of @xmath904 is the zero set of @xmath905 . hence if the curve is not immersed , then either @xmath906 and @xmath907 , or else @xmath902 and @xmath908 . this proves claim 1 . let @xmath909 claim 2 : on @xmath910 ( respectively @xmath911 ) , @xmath678 has @xmath912 ( respectively @xmath913 ) components . each component of @xmath678 has turning number @xmath914 ( respectively @xmath915 ) . the total turning number of @xmath678 is @xmath677 on each of @xmath910 and @xmath911 . by theorem [ thm : flat - torus - integers ] ( 2 ) , at the flat torus at the beginning ( respectively end ) of the flow , the profile curve sets are @xmath677 ( respectively @xmath870 ) wrapped circles . since turning numbers of the immersed profile curves are homotopy invariants , the total turning number of @xmath916 is preserved in @xmath917 and @xmath918 . similarly the total turning number of @xmath919 is preserved in @xmath920 and @xmath921 . lemma [ thm : twizzled - profile - curve ] simplifies in the case of tori of revolution . by theorem [ thm : flat - torus - integers ] , the profile curve at the flat torus is an @xmath677-wrapped circle , with turning number @xmath677 . since the flow @xmath922 $ ] induces a regular homotopy of the profile curve , then by the whitney - graustein theorem , every profile curve in the flow has turning number @xmath677 . figure [ fig : profile-3lobe ] illustrates the profile curves of the @xmath923-lobed tori of revolution . we show that twizzled tori are never embedded , and classify embedded tori of revolution . as a corollary of lemma [ thm : twizzled - profile - curve ] we have [ cor : twizzled - nonembedded ] a non - rotational spectral genus one torus in @xmath0 is never embedded . by lemma [ thm : twizzled - profile - curve ] , the profile curve sets of a @xmath676 twizzled torus have total turning number @xmath677 or @xmath870 . by theorem [ thm : flat - torus - integers ] , each of these turning numbers is strictly bigger than @xmath29 . hence the profile curve sets are not embedded . to show the surface is not embedded assume first that @xmath924 . if @xmath53 where embedded , then by lemma [ thm : twizzled - profile - curve ] the profile curve is immersed . by the inverse function theorem the inverse image under @xmath53 of the profile curve is embedded , hence if it where embedded the profile curve would be embedded , which is not true since its turning number is at least two by lemma [ thm : twizzled - profile - curve ] , giving the contradiction . because embeddedness is an open condition , during the flow @xmath924 away from isolated points , the surface is embedded also at the zeroes . [ thm : embedded ] a @xmath783 torus of revolution is embedded if and only if @xmath925 . a surface of revolution in @xmath0 is embedded if and only if its profile curve is embedded and does not meet the revolution axis . to show the embeddedness , we show that the curvature of the orthographic projection of the profile curve @xmath926 in is strictly positive . write @xmath927 and @xmath928 so the profile curve is @xmath929 . to compute @xmath930 , note that @xmath931 . the expression for @xmath932 in yields after a calculation @xmath933 with @xmath934 . the curvature of the plane curve @xmath935 is @xmath936 . note that the plane curve @xmath935 is an orthographic projection of the hemisphere to @xmath937 , not stereographic ; the curvature of the stereographic projection may change sign , as seen in figure [ fig : profile-3lobe ] . we next show that the profile curve does not meet the revolution axis for @xmath922 $ ] . since the range of @xmath426 is @xmath938 $ ] , then the range of @xmath627 is @xmath939 $ ] . hence @xmath940 , because @xmath941 , @xmath942 and @xmath943 . hence @xmath944 , so the profile curve does not meet the axis of revolution . if the profile curve is embedded , then its turning number is @xmath29 . but by the discussion after theorem [ thm : twizzled - profile - curve ] , its turning number is @xmath677 . hence @xmath925 . conversely , assume @xmath925 , so its turning number is @xmath29 . the curvature @xmath945 of the orthographic projection @xmath935 of the profile curve to @xmath378 computed above is strictly positive , so the profile curve is convex and hence embedded ( see e.g ( * ? ? ? * , proposition 1 ) ) . an equivariant torus in @xmath0 is alexandrov embedded if and only if it is a surface of revolution and singly wrapped with respect to the rotational period . a rotational torus is alexandrov embedded if and only if there exists an immersion @xmath946 \to { \mathbb{s}}^2_+$ ] into a hemisphere @xmath947 such that @xmath948 is mapped to the equator of @xmath947 and @xmath949 is mapped onto a profile curve of the torus . the resulting 3-manifold , obtained by rotating the strip is then the alexandrov embedding . every flat torus is a covering of an embedded flat torus . hence the 3-manifold is always a solid torus , and thus has fundamental group @xmath4 . the compact coverings correspond to proper subgroups of @xmath4 . hence flat alexandrov embedded tori have to be singly wrapped . this condition is stable under continuous deformations which stay away from bouquets of spheres . embedded @xmath950 tori of revolution in @xmath0 , with @xmath951 . , title="fig:",width=151 ] embedded @xmath950 tori of revolution in @xmath0 , with @xmath951 . , title="fig:",width=151 ] embedded @xmath950 tori of revolution in @xmath0 , with @xmath951 . , title="fig:",width=151 ] embedded @xmath950 tori of revolution in @xmath0 , with @xmath951 . , title="fig:",width=151 ] there are infinitely many minimal tori in @xmath0 @xcite . there are in fact already infinitely many minimal equivariant ones . theorem [ thm : mean - curvature ] shows the existence of infinitely many minimal twizzled tori . for example the @xmath952 flow family with @xmath953 is a fixed point of the involution of proposition [ prop : involution ] . the flow starts and ends at the same flat torus with opposite mean curvature , and hence it contains a minimal torus . a ( non - minimal ) example from the @xmath954 family is shown in figure [ fig : twizzled2 ] . [ thm : mean - curvature ] a spectral genus 1 flow family with endpoints @xmath676 and @xmath727 contains exactly one minimal torus if @xmath955 and no minimal tori otherwise . consider the flow from a flat torus to a flat torus through spectral genus 1 tori as described in theorem [ thm : moduli - space ] . since the mean curvature is monotonic , the flow contains a minimal torus if and only if the mean curvature of the flat tori have opposite signs , or if one of these flat tori is minimal . by a calculation , @xmath956 , @xmath957 , where @xmath958 and @xmath959 , and then @xmath960 since @xmath961 is negative at the beginning of the flow and positive at the end ( theorem [ thm : moduli - space ] ) , by proposition [ prop : involution ] , mean curvatures @xmath962 and @xmath963 of the flat tori at the beginning and end of the flow are respectively @xmath964 where @xmath965 . the flow contains a minimal torus if and only if @xmath966 and @xmath967 have the same sign , or either is @xmath804 . since the sum of these two integers is equal to @xmath968 , they are not both negative . the condition that they have the same sign , or either is @xmath804 , is then equivalent to the asserted inequality . consider the @xmath783 family of tori of revolution , and let @xmath969 . the mean curvature for the flat tori is chosen to be positive for @xmath970 and negative for @xmath971 . [ thm : rev - mean - curvature ] for spectral genus 1 tori of revolution , the mean curvature decreases monotonically from @xmath972 at the flat torus to @xmath973 at the sphere bouquet . this family contains exactly one minimal torus if @xmath974 $ ] , and no minimal tori otherwise . by , the mean curvature of the flat torus at the end of the flow ( @xmath208 ) is @xmath962 as in the assertion . by lemma [ thm : sphere - bouquet ] , the @xmath783 family of tori of revolution converges to the @xmath783 sphere bouquet as @xmath793 . the limiting sphere bouquet has mean curvature @xmath973 . the mean curvature is monotonic by theorem [ thm : moduli - space ] and hence has the specified range . the family contains a minimal torus if and only if the mean curvature has different signs at the endpoints of the flow . this occurs if and only if @xmath975 $ ] . alexandrov embedded five - lobed @xmath976 tori of revolution in @xmath0 . the turning number of the inner profile curve is @xmath977 . , title="fig:",width=204 ] alexandrov embedded five - lobed @xmath976 tori of revolution in @xmath0 . the turning number of the inner profile curve is @xmath977 . , title="fig:",width=204 ] alexandrov embedded five - lobed @xmath976 tori of revolution in @xmath0 . the turning number of the inner profile curve is @xmath977 . , title="fig:",width=204 ] the clifford torus is the only minimal embedded rotational torus in the 3-sphere . by combining the above results we have shown that amongst the infinitely many minimal equivariant tori in the 3-sphere , only one is embedded @xcite . the clifford torus is the only embedded minimal equivariant torus in @xmath0 . let @xmath978 denote the set of immersions from the oriented 2-torus @xmath675 into the oriented 3-sphere @xmath0 . we define an equivalence relation by identifying two maps in @xmath978 if they differ by an orientation preserving diffeomorphism of @xmath675 and an orientation preserving isometry of @xmath0 , and set @xmath979 . we denote the spectral genus zero maps by @xmath980 , that is @xmath981 thus @xmath982 consists of infinitely many @xmath128-families of flat tori . even though each of these families by proposition [ prop : flat - torus ] ( iii ) is a finite cover of the family of the underlying embedded rectangular torus , we need the full diversity of @xmath982 to bifurcate into all possible spectral genus one tori . the spectral genus one tori will be denoted by @xmath983 , that is @xmath984 since deformation families of rotational tori in @xmath985 flow into bouquets of spheres , we take the closure of @xmath985 by supplementing it with the limiting bouquets of spheres , and set @xmath986 the aim of this section is to show that this _ completed _ moduli space of equivariant tori @xmath987 is connected ( theorem [ th : connected ] ) . we have already seen that the moduli space of equivariant tori in the 3-sphere is a graph , which consists of : 1 . edges of families of spectral genus zero tori ; 2 . edges of families of spectral genus one tori ; 3 . bifurcation vertices in @xmath982 that connect with other vertices in @xmath982 via spectral genus one edges by theorem [ thm : moduli - space ] . by proposition [ prop : flat - torus ] ( iii ) any element in @xmath982 is isogenic to the unique ( up to isomorphism ) embedding of a rectangular lattice with the same mean curvature . hence each edge in @xmath982 contains a unique minimal torus , obtained via an isogeny from the clifford torus . if we identify two isogenies which differ only by an isomorphism of the domain , then we have a one - to - one correspondence between isomorphy classes of isogenies and co - finite sublattices of @xmath488 . hence we can identify the connected components of @xmath982 with co - finite sublattices of @xmath488 . we say that two such sublattices are connected , if the corresponding genus zero edges are connected in @xmath988 . we associated to the bifurcation vertices triples @xmath989 with @xmath990 and @xmath991 . in the proof of theorem [ thm : flat - torus - integers ] ( 2 ) we showed that triples correspond to the lattices . the genus one edges described in theorem [ thm : moduli - space ] yield four isomorphisms of each of these lattices onto one of those lattices corresponding to the triples @xmath727 . furthermore , the genus zero edge corresponding to a sublattice of one of the former lattices is connected by an isogenic genus one edge with the corresponding sublattice of one of the latter lattices . but we do not use these isomorphisms of the lattices onto those lattices corresponding to @xmath727 . we shall make use of these isomorphisms only in case of embedded tori with @xmath925 and @xmath992 . in this case rotation periods are preserved , and up to transformations @xmath660 and @xmath661 these isomorphisms are of the form @xmath993 \(ii ) if @xmath996 , then @xmath999 holds for all @xmath1000 . hence @xmath1001 } = \lambda^\ast$ ] . conversely , if @xmath995 } = \lambda^\ast$ ] , then @xmath1002 holds for all @xmath1000 . in particular @xmath1003 , which implies @xmath925 so as not to contradict the assumption @xmath1004 . we will show that any edge of rotational tori in @xmath982 is connected to the edge of embedded rotational tori , or equivalently that any lattice @xmath1005 of a rotational torus is connected to the @xmath488 lattice . by proposition [ th : lattices1 ] ( iii ) the edge of embedded rotational tori in @xmath982 contains all the vertices @xmath1006 with @xmath998 . this edge is connected with all the edges that contain the vertices @xmath1007 with @xmath998 . hence the lattice @xmath1008}=\lambda^\ast$ ] is connected to the lattice @xmath1009}= \gamma_1^\ast{\mathbb{z}}+({\ell_2}-1)\gamma_2^\ast{\mathbb{z}}$ ] . furthermore , the lattice @xmath1010 } = \lambda^\ast$ ] is connected to the lattice @xmath1011}= ( { \ell_2}-1)\gamma_1^\ast{\mathbb{z}}+ \gamma_2^\ast{\mathbb{z}}$ ] . sublattices @xmath1012}$ ] are connected along genus one edges isogenic to the former genus one edges with @xmath1013}$ ] by the isomorphism . the deformation through spectral genus one , possibly also passing through bouquets of spheres as described in theorem [ thm : moduli - space ] . in this case we write @xmath1014 the deformation along an edge of flat tori , passing from one bifurcation vertex to another one : suppose @xmath989 is such that @xmath1015 and @xmath1016 . then from @xmath1017 get that also @xmath1018 . in this case the transformation @xmath1019 acts on the corresponding lattices as the transformation ( d ) , which interchanges the four lattices . in such a case we write @xmath1020 if @xmath854 is odd , then we have @xmath1021 } \longleftrightarrow 2n_1\gamma_1^\ast+n_2\gamma_2^\ast\in \gamma_{[2{\ell_0},{\ell_1},2{\ell_2}]}.\ ] ] due to lemma [ rotational connected ] both genus zero edges corresponding to the lattices @xmath1022 and @xmath1023 are connected with the edge corresponding to @xmath488 . if we apply an isogeny to these families we obtain with a deformation of a genus zero edge corresponding to the lattice @xmath1024 to another genus zero edge corresponding to the lattices @xmath1025 and @xmath1026 , respectively . in combination with we write @xmath1027 we shall show that it is possible to successively reduce @xmath854 until @xmath992 . we can add to @xmath855 multiples of @xmath677 without changing the lattices . we pick the smallest of all possible @xmath855 and obtain @xmath1028 in case of equality , the lattices are of the form @xmath1029 . in this case lemma [ rotational connected ] connects @xmath473 with @xmath488 . therefore we may assume @xmath1016 . in the deformation we pick the smaller of the first entries @xmath677 and @xmath1030 . hence we can assume that @xmath1031 , and now we have the following sequence of deformations @xmath1032 if @xmath1033 then @xmath1034 , so @xmath854 has decreased by this deformation . if @xmath1035 , then we distinguish two cases : if @xmath854 and @xmath1036 were both even , then @xmath855 would be even , contradicting that @xmath1004 . hence we just need to consider the two cases @xmath1036 is odd , and @xmath854 is odd . if @xmath854 is odd , then @xmath1039 obviously for @xmath1040 the lattices are of the form @xmath1029 . hence in all cases either the lattices are connected with @xmath488 or @xmath854 is reduced . by repeating the above procedure finitely many times we eventually achieve @xmath683 , which we have already dealt with in lemma [ rotational connected ] . since @xmath1043 , there exists @xmath1044 with @xmath1045 , and @xmath484 is not a multiple of another element in @xmath488 . let @xmath1046 such that @xmath1047 . since @xmath1048 is finite , there exist smallest integers @xmath1049 with @xmath1050 such that @xmath1051 and @xmath1052 . consider the homomorphism @xmath1053 . by definition of @xmath1054 we have that @xmath1055 , so that @xmath1 maps @xmath473 to a sublattice of @xmath1056 . every such homomorphism is of the form @xmath1057 with @xmath1058 . by adding appropriate multiples of @xmath1059 to @xmath1060 we can achieve @xmath663 . if @xmath1041 is a co - finite sublattice , then by lemma [ th : lattice - lemma ] the corresponding genus zero edge contains a bifurcation vertex with triple @xmath676 and integers @xmath663 . by lemma [ th : z2lattice ] the corresponding lattices are connected to the lattice @xmath488 . an isogeny of this path connects the edge corresponding to @xmath473 with a genus zero edge corresponding to @xmath1061 with @xmath1062 . repeating this argument we can successively reduce the order until @xmath1063 . m. kilian and m. u. schmidt , _ on infinitesimal deformations of cmc surfaces of finite type in the 3-sphere _ , proc . 16th ocu intl . acad . symp . 2008 , ocami studies , vol . 3 , osaka municipal universities press , 2009 . i. m. krichever , _ whitham theory for integrable systems and topological quantum field theories _ , new symmetry principles in quantum field theory ( cargse , 1991 ) , nato adv . 295 , plenum , new york , 1992 , pp .

we present a deformation for constant mean curvature tori in the 3-sphere . we show that the moduli space of equivariant constant mean curvature tori in the 3-sphere is connected , and we classify the minimal , the embedded , and the alexandrov embedded tori therein .

SECTION 1. SHORT TITLE. This Act may be cited as the ``Securing Aircraft From Explosives Responsibly: Advanced Imaging Recognition Act of 2010'' or ``SAFER AIR Act of 2010''. SEC. 2. FINDINGS; SENSE OF CONGRESS. (a) Findings.--Congress makes the following findings: (1) On December 25, 2009, Umar Farouk Abdulmutallab, a national of Nigeria, allegedly attempted to detonate a concentration of pentaerythritol tetranitrate aboard Northwest Airlines Flight 253 as the aircraft prepared to land in Detroit, Michigan. (2) Pentaerythritol tetranitrate is an explosive chemical compound that cannot be detected by conventional metal detection devices like those that Mr. Abdulmutallab allegedly passed through at airport checkpoints in Nigeria and the Netherlands. (3) However, detection devices employing advanced imaging technology (formerly known as whole-body imaging), and other technologies currently available, such as trace detection equipment, can be used to identify or detect on-body plastic explosives and other nonmetallic explosives, including pentaerythritol tetranitrate, as well as other materials that can be used as weapons. (4) Despite these capabilities, advanced imaging technology has not been fully deployed in the United States or abroad. Through 2009, the Department of Homeland Security used 40 advanced imaging technology units in 19 airports in the United States. Only 6 of those airports used advanced imaging for primary screening, and only then in a limited role at the airport. (5) The Department of Homeland Security has announced plans to deploy 950 additional advanced imaging technology units through fiscal year 2011, for use at approximately 2,200 checkpoints at commercial airports. (6) Other detection technologies complement, and may be used in combination with, advanced imaging technology units as part of a multi-layered approach at the airport checkpoint, and need to be tested and deployed more consistently. These technologies include devices that detect traces of explosives from swabs of passengers or carry-on baggage and advanced technology machines that conduct multiple-view examinations of carry-on baggage. (b) Sense of Congress on Privacy Concerns Related to the Use of Advanced Imaging Technology.--It is the sense of Congress that the Department of Homeland Security should-- (1) increase efforts to address privacy concerns with respect to the screening of passengers at airports using advanced imaging technology; and (2) conduct additional lab and operational testing of advanced imaging technology and deploy, in a reasonable period of time, technology-- (A) to standardize images produced using advanced imaging technology; (B) to remove personally identifying characteristics from the images viewed by transportation security officers, while providing such officers with the information necessary to make a clear assessment of the threat posed by individual passengers; and (C) to upgrade equipment to be able to detect new threats without major capital expenditures. SEC. 3. POLICY OF THE UNITED STATES WITH RESPECT TO PRIMARY SCREENING TECHNOLOGIES AT AIRPORT CHECKPOINTS. It is the policy of the United States to aggressively seek, develop, and deploy, in a timely fashion and in sufficient numbers, primary screening technologies capable of detecting and protecting against threats to domestic and international aviation travel that cannot be effectively and efficiently detected by other technologies currently more commonly utilized in airports, such as metal detection. SEC. 4. USE OF ADVANCED TECHNOLOGY FOR SCREENING AIRCRAFT PASSENGERS. Section 44901 of title 49, United States Code, is amended by adding at the end the following: ``(l) Use of Advanced Technology for Screening Passengers.-- ``(1) In general.--The Secretary of Homeland Security shall ensure that advanced imaging technology and other advanced technology with the capability to detect weapons, on-body plastic explosives, and other nonmetallic explosives, are deployed, individually or in combination with each other, in a timely and effective manner for the primary screening of aircraft passengers in accordance with this subsection. ``(2) Technological and operational certification.-- ``(A) In general.--Not later than 30 days after the date of the enactment of the Securing Aircraft From Explosives Responsibly: Advanced Imaging Recognition Act of 2010, the Secretary of Homeland Security shall certify to Congress that-- ``(i) the Department of Homeland Security has the capacity to deploy advanced technology described in subparagraph (B) at airport checkpoints to detect weapons, on-body plastic explosives, and other nonmetallic explosives; and ``(ii) those technologies will be deployed at each airport checkpoint in the United States by 2013 in sufficient quantities to detect and deter operational threats from weapons, on-body plastic explosives, and other nonmetallic explosives. ``(B) Advanced technology described.--Advanced technology described in this subparagraph is-- ``(i) advanced imaging technology; or ``(ii) such other technology as the Secretary of Homeland Security determines, and certifies to Congress-- ``(I) provides a capability to detect weapons, on-body plastic explosives, and other nonmetallic explosives that is comparable to, or greater than, the capability to detect such weapons and explosives provided by advanced imaging technology; and ``(II) will be used in a manner suitable to detect such weapons and explosives. ``(3) Primary screening of passengers.-- ``(A) In general.--Except as provided in subparagraph (B), all primary screening of passengers shall be conducted using advanced imaging technology or another advanced technology described in paragraph (2)(B)(ii). ``(B) Alternative screening method for passengers with privacy concerns.-- ``(i) In general.--The Secretary of Homeland Security shall provide passengers with an option for primary screening other than the use of advanced imaging technology or another advanced technology described in paragraph (2)(B)(ii). ``(ii) Options.--The alternative option for primary screening provided to passengers under clause (i) shall be either-- ``(I) to both pass through a metal detector and undergo a pat-down search; or ``(II) screening using such other method or combination of methods for screening passengers as the Secretary determines, and certifies to Congress, is appropriate and effective. ``(C) Provision of information.--Passengers shall be provided with-- ``(i) information regarding the images produced by advanced imaging technology to detect on-body plastic explosives and other nonmetallic explosives; ``(ii) information regarding the privacy protections provided under paragraph (4); and ``(iii) sufficiently detailed notice and an explanation of the alternative option for primary screening provided to passengers under subparagraph (B). ``(4) Privacy protections for passengers.-- ``(A) Nonretention of images.--Except as provided in subparagraph (B)(ii), all advanced imaging technology equipment used by the Department of Homeland Security at an airport checkpoint shall be configured so that images produced using the equipment-- ``(i) cannot be stored, transferred, copied, or printed; and ``(ii) are permanently removed from the screen after the passenger is cleared to pass through the airport checkpoint. ``(B) Standardization and blurring of images.-- ``(i) In general.--The Secretary of Homeland Security shall ensure that any advanced imaging technology equipment used by the Department of Homeland Security to screen passengers be configured so that-- ``(I) all facial features on a passenger's image are blurred; and ``(II) passenger images are standardized to the greatest extent possible while allowing for detection of individual on-body threats. ``(ii) Transfer of nonstandardized images.--An image produced using advanced imaging technology that shows personal or nonstandardized images shall be transferred using a secure connection to a location that enables an employee of the Department of Homeland Security to view the image without risking the exposure of the image to the public. ``(C) Prohibition on presence of cameras while viewing images.--An employee of the Department of Homeland Security viewing an image of a passenger produced using advanced imaging technology-- ``(i) may not have a camera or cell phone present; and ``(ii) if viewing the image in a location described in subparagraph (B)(ii), shall communicate with other employees of the Department of Homeland Security using a wireless headset or another comparable method of communication that does not allow for the transmission of the image. ``(5) Reports.-- ``(A) Department of homeland security.--Not later than 1 year after the date of the enactment of the Securing Aircraft From Explosives Responsibly: Advanced Imaging Recognition Act of 2010, and every 2 years thereafter, the Secretary of Homeland Security shall submit to Congress a report on the implementation of this subsection that includes-- ``(i) an assessment of existing and emerging threats presented by on-body plastic explosives, other nonmetallic explosives, and other items undetectable by conventional metal detectors deployed at airport checkpoints; ``(ii) an assessment of the capabilities and effectiveness of primary screening using advanced imaging technology and any other advanced technology described in paragraph (2)(B)(ii) used by the Department of Homeland Security in combating any threat described in clause (i); ``(iii) an estimate of the percentage of passengers who choose to be screened-- ``(I) by advanced imaging technology or using another advanced technology described in paragraph (2)(B)(ii); and ``(II) using an alternative option for primary screening provided to passengers under paragraph (3)(B); and ``(iv) a description of the measures taken to protect the privacy of passengers screened using advanced imaging technology and an assessment of compliance with those measures. ``(B) Government accountability office.--Not later than 180 days after the date of the enactment of the Securing Aircraft From Explosives Responsibly: Advanced Imaging Recognition Act of 2010, and every 2 years thereafter, the Comptroller General of the United States shall conduct a study and submit to Congress a report on the costs of carrying out this subsection, including the costs relating to procuring the necessary technology, construction at airports, and training and deploying employees of the Department of Homeland Security to use new technologies. ``(6) Definitions.--In this subsection: ``(A) Advanced imaging technology.--The term `advanced imaging technology'-- ``(i) means a device that creates a visual image of an individual showing the surface of the skin and revealing other objects on the body as applicable, including narcotics, explosives, and other weapons components; and ``(ii) includes devices using backscatter x-rays or millimeter waves and devices referred to as `whole-body imaging technology' or `body scanning'. ``(B) Airport checkpoint.--The term `airport checkpoint' has the meaning given the term `screening location' in section 1540.5 of title 49, Code of Federal Regulations (or any corresponding similar rule or regulation). ``(C) Pat-down search.--The term `pat-down search' means a physical inspection of the body of an individual conducted in accordance with the standard operating procedure described in the official training manual of the Transportation Security Administration of the Department of Homeland Security. ``(D) Primary screening.--The term `primary screening' means the initial examination of any passenger at an airport checkpoint, including using available screening technologies to detect weapons, explosives, narcotics, or other indications of unlawful action, in order to determine whether to clear the passenger to board an aircraft or to further examine the passenger.''. SEC. 5. DEVELOPMENT OF NEW SCREENING TECHNOLOGIES. Nothing in this Act, or the amendments made by this Act, shall be construed to discourage the Secretary of Homeland Security from developing and deploying advanced technologies for aviation screening to protect the traveling public from emerging threats. The Secretary shall continue to develop and deploy such new advanced technologies. SEC. 6. AUTHORIZATION OF APPROPRIATIONS. There are authorized to be appropriated such sums as may be necessary to carry out this Act and the amendments made by this Act.

Securing Aircraft From Explosives Responsibly: Advanced Imaging Recognition Act of 2010 or SAFER AIR Act of 2010 - Expresses the sense of Congress that the Department of Homeland Security (DHS) should: (1) increase efforts to address privacy concerns regarding the screening of passengers using advanced imaging technology at airports; and (2) conduct additional testing of advanced imaging technology; and (3) deploy technology to standardize images, remove personally identifying characteristics, while providing transportation security officers with necessary information, and upgrade equipment to detect new threats without major capital expenditures. Declares it to be U.S. policy to aggressively seek, develop, and timely deploy primary screening technologies capable of detecting and protecting against threats to domestic and international aviation travel that cannot be effectively and efficiently detected by other technologies currently more commonly used, such as metal detectors. Directs the Secretary to ensure that advanced imaging technology and other advanced technology with capability to detect weapons, on-body plastic explosives, and other nonmetallic explosives are timely deployed for the primary screening of aircraft passengers. Requires the Secretary to provide passengers with an option for primary screening other than the use of such technologies. Requires all advanced imaging technology equipment used at airport checkpoints to be configured so that passenger: (1) images are not retained; and (2) facial features are blurred, while allowing detection of individual on-body threats. Prohibits DHS employees from having cameras or cell phones present while viewing such images. Requires such employees to communicate with other DHS employees using a wireless headset or another comparable method of communication that does not allow for the transmission of the image.

dilated cardiomyopathy ( dcm ) describes a group of myocardial diseases that have a progressive course characterized by ventricular dilation and systolic and diastolic dysfunction ( 1 - 7 ) . dcm can be idiopathic , but infectious causes ( viruses , bacteria , fungi , and parasites ) , toxins , excessive alcohol consumption , chemotherapeutic agents ( doxorubicin ) , genetic mutations , and ischaemic heart disease might also play a part in the aetiology ( 1 , 5 , 7 ) . the incidence of idiopathic dcm in the population is 5 - 8/100,000 ( 2 , 5 , 7 ) . complications that are most frequently seen include congestive heart failure and malignant arrhythmias ( the most frequent cause of death ) ( 5 ) . the five - year survival rate after confirmation of the diagnosis is 25 - 40% ( 5 ) . in this case report , we present a successful regional anesthetic management , thoracic epidural anesthesia ( tea ) , which was used for a patient who had serious idiopathic dcm and underwent laparotomy . a 41-year - old female patient who weighed 45 kg and measured 155 cm in height was scheduled for hysterosalpingo - oophorectomy because of myoma uteri . the patient had been diagnosed with idiopathic dcm two years earlier and with bronchial asthma . she was taking carvedilol , furosemide , spironolactone , digoxin , and a salbutamol inhaler . the patient s exertional capacity ( new york heart association functional classification ii ) was also restricted ( < 2 met ) . although her laboratory values , including her bleeding profile , were within normal limits , the patient demonstrated a severely restricted pattern in respiratory function tests , with forced vital capacity ( fvc ) : 33% ; forced expiratory volume 1 ( fev1 ) : 37% ; and fev1/fvc : 90% . her echocardiography detected an ejection fraction ( ef ) of 25% , mild degrees of aortic , mitral , and tricuspid regurgitation , pulmonary hypertension ( 40 mm hg ) , and left ventricular global hypokinesia . bronchiectasis was also detected through computed tomography ; the patient s posteroanterior pulmonary radiographs revealed cardiomegaly ( figures 1 and 2 ) . the patient was categorized in asa iv ( american society of anesthesia ) . chest radiography demonstrating cardiomegaly computed tomography image of the area of bronchiectasis when the patient was brought into the operating room , measurements were taken of her mean arterial pressure ( map ) ( 90 mm hg ) , heart rate ( hr ) ( 100 bpm ) , respiratory rate ( br ) ( 2 - 14 / min ) , and ambient oxygen saturation in the room air ( spo2 ) ( 96 % ) . the patient underwent radial artery and central venous cannulation under local anesthesia to monitor arterial pressure and central venous pressure ( cvp ) . epidural anesthesia was planned for the patient , and ringer s lactate solution ( 200 ml ) was administered before the procedure to prevent sudden changes in her hemodynamic status . then , while the patient was sitting upright , an 18 g tuohy needle ( portex ) was inserted at midline between the t11 - 12 intervertebral space , to determine epidural space with the loss of resistance technique , and the catheter was advanced for 5 cm into the thoracic region . the correct position of the catheter was verified through a test dose ( 3 ml ; 2% lidocaine + 1:200 000 adrenaline ) and a total of 15 ml of local anesthetic mixture ( 0.25% bupivacaine + 1% lidocaine ) was delivered through the catheter in divided doses of 4 - 5 ml to attain a sensorial level of t5 . before surgery , midazolam ( 1 mg ) was administered for sedation and , during the surgery , o2 ( 5l / min ) was delivered by mask . during the 75-minute surgical procedure , map , cvp , spo2 , hr , and br were all maintained at levels of 20% of the preoperative values . the patient experienced one hypotensive attack ( 80/40 ) and responded to ephedrine ( 5 mg ) . during this episode , the patient s cvp values were maintained at approximately 9 - 10 mm hg , and she received ringer s lactate infusion ( 350 ml ) . for postoperative analgesia , patient - controlled analgesia ( 0.1% levobupivacaine + 2 mcg / ml fentanyl , bolus 5 ml , infusion 3 ml / h , and locked - in time of 45 min ) was applied , and the patient was transferred to the intensive care unit for close follow - up . since vital signs demonstrated a stable course , the patient was transferred to the surgical ward . the most important problem in dcm is systolic dysfunction , and left cardiac failure are also common ( 1 , 6 ) . in addition to these , severe ventricular arrhythmias and embolisms may be seen ( 3 , 5 ) . lower ef ( < 0.25 ) increases the risks of hypokinetic left ventricular failure and mitral - tricuspid regurgitation and enhances the patient s risk of postoperative cardiac complication ( 5 ) . during the preoperative period , echocardiography is required for the evaluation of ventricular and valvular functions ( 6 ) . in patients with dcm , potassium and magnesium deficiencies can be seen secondary to the chronic use of diuretics . since these electrolyte abnormalities can predispose patients to cardiac arrhythmias , they should be corrected during the preoperative period ( 6 ) . this can lead to serious hypotension during anesthetic applications , while a lack of attention to hydration can result in congestive heart failure ( 4 ) . therefore , patients need to receive optimal medical therapy during the preoperative period , and with adequate planning anesthetic management can be successfully achieved ( 7 ) . our main targets in anesthetic management include avoiding or minimising potential myocardial depression induced by drugs , maintaining normovolemia , preventing increases in ventricular afterload , and avoiding tachycardia ( 4 , 6 ) . cvp monitoring provides information about preload of the right ventricle of the heart ( 6 ) . pulmonary catheterization can provide information about the filling pressures of the left ventricle of the heart ( 1 , 3 , 6 ) . however , the absence of any marked impact that this monitoring can have on mortality and morbidity , together with its risk of serious complications , has limited the use of this procedure ( 6 ) . transesophageal echocardiography ( tee ) is a useful technique for monitoring dynamic changes in cardiac performance and evaluating volemic status , fluid replacement , and inotropic therapies ( 6 , 8) . however , the inability to use tee in patients who are awake restricts its use in regional anesthesia . application of general anesthesia in idiopathic dcm patients significantly increases the risk of heart failure , myocardial ischemia and arrhythmia ( 7 ) . however , regional anesthesia decreases the frequency of deep vein thrombosis , damage to the central nervous system , and postoperative respiratory complications and also facilitates early mobilization with improved postoperative analgesia ( 4 ) . in addition , a patient who is conscious can alert us to sudden changes in cerebral functions or new - onset angina pectoris ( 4 ) . many authors have argued that tea can be recommended for patients who have restricted cardiac reserves and are to undergo abdominal surgery ( 9 , 10 ) . tea has beneficial effects on cardiac functions because it decreases preload and afterload ( 11 ) . because the development of a sympathetic block is slower with tea than with the spinal anesthesia , the probability of developing severe hypotension and myocardial ischemia is reduced ( 6 ) . in patients who have dcm , therefore , anti - arrhythmic medications should be available , and lidocaine , amiodarone , and a defibrillator should all be on hand in the operating room ( 4 , 12 ) . in addition , patients should be monitored very closely for hypotension , and a drop of more than 20% from the baseline value should not be allowed . a positive inotropic agent should be available as well , in case it is needed ( 1 , 6 ) . improved management of postoperative analgesia is also required to prevent increases in heart rate and vascular resistance ( 6 ) . since close monitoring of fluid replacement is essential , patients should continue to be followed in the intensive care unit during the postoperative period ( 6 ) . in conclusion , tea can be safely and effectively applied in idiopathic dcm patients with appropriate preoperative preparation , closer hemodynamic monitoring , and meticulous titration of local anesthetic agents .

idiopathic dilated cardiomyopathy is a primary myocardial disease with unknown aetiology . this disease follows a prospective course that is characterized by ventricular dilation and impaired myocardial dilation . congestive heart failure and malignant arrhythmias are the most widespread complications . the incidence of idiopathic dilated cardiomyopathy in the general population is 5 - 8/100.000 . because of the increased risks of perioperative complications , anesthetic management of this disease requires the application of a specific technique . this case report demonstrates the application of successful regional anesthetic management ( thoracic epidural anesthesia ) in a patient who had been diagnosed with severe idiopathic dilated cardiomyopathy .

The Romney campaign stressed Monday that states should take the lead in responding to emergencies like hurricanes. But the campaign said Romney would not abolish the Federal Emergency Management Agency. “Gov. Romney believes that states should be in charge of emergency management in responding to storms and other natural disasters in their jurisdictions,” Romney spokesman Ryan Williams said in a statement. “As the first responders, states are in the best position to aid affected individuals and communities, and to direct resources and assistance to where they are needed most. This includes help from the federal government and FEMA.” Text Size - + reset Yard signs as missiles (PHOTOS: Hurricane Sandy) A campaign official added that Romney would not abolish FEMA. The statement came after The Huffington Post highlighted Romney’s comments from a June 2011 CNN primary debate in which Romney said states should take on a bigger role in responding to disasters. “Mitt Romney In GOP Debate: Shut Down Federal Disaster Agency, Send Responsibility To The States,” read the Huffington Post’s headline. “FEMA is about to run out of money, and there are some people who say, ‘Do it on a case-by-case basis.’ And there are some people who say, ‘You know what, maybe we’re learning a lesson here that the states should take on more of this role.’ How do you deal with something like that?” debate moderator John King asked Romney during the debate, pointing to the May 2011 tornado that killed more than 150 people in Joplin, Mo. “Absolutely. And every time you have an occasion to take something from the federal government and send it back to the states, that’s the right direction. And if you can go even further and send it back to the private sector, that’s even better,” Romney responded. “Instead of thinking in the federal budget, ‘What we should cut?’ we should ask ourselves the opposite question, ‘What should we keep?’ We should take all of what we’re doing at the federal level and say, ‘What are the things we’re doing that we don’t have to do?’ And those things we’ve got to stop doing,” Romney continued. (PHOTOS: Political plans: Rock me like a hurricane) ||||| Back when he was being “severely conservative,” Mitt Romney suggested that responsibility for disaster relief should be taken from the big, bad federal government and given to the states, or perhaps even privatized. Hurricane Sandy would like to know if he’d care to reconsider. The absurd, and dangerous, policy prescription came in a GOP primary debate in June. Moderator John King said he had recently visited communities affected by severe weather and noted that the Federal Emergency Management Agency “is about to run out of money.” Eugene Robinson writes a twice-a-week column on politics and culture, contributes to the PostPartisan blog, and hosts a weekly online chat with readers. In a three-decade career at The Post, Robinson has been city hall reporter, city editor, foreign correspondent in Buenos Aires and London, foreign editor, and assistant managing editor in charge of the paper’s Style section. View Archive “There are some people . . . who say, you know, maybe we’re learning a lesson here that the states should take on more of this role,” King said. “How do you deal with something like that?” Romney replied: “Absolutely. Every time you have an occasion to take something from the federal government and send it back to the states, that’s the right direction. And if you can go further and send it back to the private sector, that’s even better.” Romney went on to express the general principle that, given the crushing national debt, “we should take all of what we’re doing at the federal level and say, ‘What are the things we’re doing that we don’t have to do?’ ” King gave him a chance to back off: “Including disaster relief, though?” Romney didn’t blink. “We cannot afford to do those things without jeopardizing the future for our kids,” he said, adding that “it is simply immoral . . . to rack up larger and larger debts and pass them on to our kids.” Now, with an unprecedented and monstrous storm bashing the East Coast, this glib exercise in ideological purity is newly relevant. Was Romney really saying that the federal government should abdicate the task of responding to natural disasters such as the one now taking place? Yes, he was. Did he really mean it? Well, with Romney, that’s always another question. As the legendary Watergate source Deep Throat never actually said: “Follow the money.” The dishonest “solution” proposed by Romney and running mate Paul Ryan for the federal government’s budget woes relies largely on a shell game: Transfer unfunded liabilities to the states. Most disastrously, this is what Romney and Ryan propose for Medicaid, the health-care program for the poor. The GOP plan would give the states block grants that would not begin to cover Medicaid’s rising costs. Governors and legislatures would be forced to impose draconian cuts, with potentially catastrophic impact for millions of Americans. Medicaid’s most expensive role — and thus, under Romney, the most imperiled — is to fund nursing-home care for seniors who classify as “poor” only because they have exhausted their life savings. Transferring the onus of Medicaid and other programs to the states would save money only by making it impossible to provide services at current levels. For the hard-right ideologues who control the Republican Party, this would be a good thing. Our society has become too dependent on government, they believe, too “entitled” to benefits; we are unwilling to “take personal responsibility and care for” our lives, as Romney said in his secretly recorded “47 percent” speech. Romney’s budget proposals would end all this coddling — except for the Pentagon and its contractors, who would get a big boost in federal largess, and of course, the wealthy, who would get a huge tax cut. So-called “discretionary” federal spending would be sharply reduced. This would include spending for such agencies as FEMA. So yes, even if Romney was just pandering to the right-wing base at that June debate, one consequence of his policies would be to squeeze funding for federal emergency relief. I guess having to survive a few hurricanes, tornados and earthquakes on our own would certainly foster personal responsibility. And by the way, why is it that we’re having such a huge hurricane make landfall in such an unusual place at such a late date in the season? Is this another of those freakish once-in-a-century weather events that seem to be happening so often these days? I know it’s impossible to definitively blame any one storm on human-induced atmospheric warming. But I’m sorry, these off-the-charts phenomena are becoming awfully commonplace. By the time scientists definitively establish what’s happening, it will be too late. As has been noted, the words “climate change” were not spoken during the presidential debates. Hurricane Sandy wants to know why. [email protected]

– There's something of a Sandy-related brouhaha swirling around comments Mitt Romney made in the ancient days of 2011: Seems that when asked during a Republican debate about disaster relief, Romney sounded like he wanted to gut FEMA, saying he'd shift responsibility for disaster management to the states—or even private firms. Said Romney: "Every time you have an occasion to take something from the federal government and send it back to the states, that’s the right direction. And if you can go further and send it back to the private sector, that’s even better." Asks Eugene Robinson at the Washington Post: "Hurricane Sandy would like to know if he’d care to reconsider." "Even if Romney was just pandering to the right-wing base at that June debate, one consequence of his policies would be to squeeze funding for federal emergency relief." The New York Times editorial board echoes Robinson, asking, "Does Mr. Romney really believe that financially strapped states would do a better job than a properly functioning federal agency?" The Romney campaign took the opportunity to clarify its position, Politico reports: "States should be in charge of emergency management in responding to storms and other natural disasters in their jurisdictions." But he wouldn't abolish FEMA: The states would act "with help from the federal government and FEMA."

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 ||||| The father of a Florida shooting survivor who accused CNN of wanting him to ask a “scripted” question during a town hall on gun rights last week admitted to altering the contents of an email he received from a producer working on the show. Glenn Haab, the father of Marjory Stoneman Douglas High School student Colton Haab, told The Associated Press on Tuesday that he left out some words when forwarding an email that he and his son received from CNN producer Carrie Stevenson. Haab sent an altered version of the email to HuffPost and Fox News last week in an attempt to corroborate his son’s claim. He told AP that there was “nothing malicious behind” his decision to leave out certain words. But the omitted words show that CNN was clearly asking his son to stick to asking the question he had already submitted. CNN hit back against the claims on Friday, releasing a copy of the email exchange that shows Stevenson was informing Haab that his son had to ask a question “that he submitted” instead of a 700-word opening statement plus three questions and a closing statement that was sent over to the network after one question had already been agreed upon. Stevenson said in the email that they wanted to allow as many students as possible to ask questions, and the version Colton’s father submitted was “way too long.” ||||| CNN is denying reports that it asked a Florida school shooting survivor to read a “scripted” question during a town hall debate on gun violence that aired on the network Wednesday night. Colton Haab, a junior at Marjory Stoneman Douglas High School in Parkland, Florida, where 17 people were gunned down last week, told local media Wednesday that he declined an invitation to appear on CNN’s program. He said he’d wanted to speak about the possibility of putting more armed guards in schools to protect students ― but, he said, CNN squelched his proposed remarks. “CNN had originally asked me to write a speech and questions, and it ended up being all scripted,” Haab told local ABC affiliate WPLG. “I don’t think that it’s going to get anything accomplished. It’s not gonna ask the true questions that all the parents and teachers and students have.” The network on Thursday vehemently denied Haab’s accusation. “There is absolutely no truth to this,” CNN said in a statement. “CNN did not provide or script questions for anyone in last night’s town hall, nor have we ever.” “After seeing an interview with Colton Haab, we invited him to participate in our town hall along with other students and administrators from Marjory Stoneman Douglas High School,” the statement says. “Colton’s father withdrew his name from participation before the forum began, which we regretted but respected.” CNN invited Haab to appear on the network Thursday “to discuss his views on school safety,” according to the network’s statement. Colton Haab did not immediately respond to HuffPost’s request for comment. A CNN source told HuffPost that the town hall was intended to give participants a chance to ask a question, but Haab wanted to read an “extensive” speech. Colton’s father, Glenn Haab, declined to have his son participate after the network refused to let his son read the full speech, according to the source. Glenn Haab told HuffPost that a CNN producer told him Colton’s speech ― which consisted of an opening statement, three questions and closing remarks ― was “too long,” and that Colton would have to stick to asking one question. The elder Haab said he told the producer that Colton wouldn’t read “one short question” without the option of first presenting the audience with “extremely relevant” background information. Colton, a member of the high school’s Junior Reserve Officers ’ Training Corps, helped usher dozens of students to safety during last week’s shooting. He told Fox News on Saturday that he believed the high school’s assistant football coach, Aaron Feis, who was killed in the massacre, could have stopped the shooter if he’d been armed. “Unfortunately, gun control, it’s definitely needed a little bit more,” Haab told Fox News on Saturday. “I believe that if we did bring firearms on campus to teachers that are willing to carry their firearm... if they got their correct training for it, I think that would be a big beneficial factor into school safety.” ||||| Media critic CNN appears to have had enough. On Friday afternoon, the network released email correspondence between one of its producers, Carrie Stevenson, and a student from Marjory Stoneman Douglas High School after last week’s school shooting in Parkland, Fla. The exchanges roared into the news following Wednesday night’s CNN town hall meeting on gun violence. Colton Haab, 17, told a TV station in Florida that he was disappointed with the network: “CNN had originally asked me to write a speech and questions and it ended up being all scripted,” he told ABC affiliate WPLG-TV. He did not attend the town hall. The “scripted” remarks acquired their own Internet nutritional system, feeding an attack that CNN was seeking to insert bias into the proceedings. CNN strenuously denied that claim on Thursday, both before and after President Trump picked up the story based on a report on the Fox News program “Tucker Carlson Tonight”: There is absolutely no truth to this story -- and we can prove that. CNN did not provide or script questions for anyone in last night's town hall, nor have we ever. Those are the facts. #FactsFirst 🍎 — CNN Communications (@CNNPR) February 23, 2018 In a post on Friday, the Erik Wemple Blog published excerpts from the emails in which Stevenson negotiated Haab’s participation in the event. Since then, the story has continued to develop: A CNN spokesman tells the Erik Wemple Blog that the network has received inquiries from other outlets stemming from what the network says are doctored portions of that correspondence that paint CNN in a negative light. To counter those leaks, CNN has authorized the publication of the emails below. Here’s a list of proposed questions from Haab: As Stevenson and Haab were discussing the matter, Colton Haab’s father, Glenn Haab, passed along several pages of “background” points that the family wanted Colton Haab to recite to contextualize the question that he was supposed to pose to Sen. Bill Nelson (D-Fla.). After Stevenson examined the proposal, she wrote this email to Glenn Haab: Glenn Haab responded as follows: According to a CNN spokesman, Fox News and HuffPost on Friday presented the network with a misleading version of the second email as part of their due diligence in pursuing the story. Whereas the correspondence supplied by CNN, above, makes clear that Stevenson was insisting that Colton Haab use a question that he himself had already “submitted” — prefaced by a lead-in that the student had already articulated in a “Fox & Friends” appearance, and that Haab proposed in a phone call with Stevenson — the allegedly doctored version of the correspondence suggests a different scenario. CNN has disclosed the email that Carlson’s Fox News program had inquired about. It chops off the part about “that he submitted,” as below: A CNN source claims that the edit leaves the network open to the charge that it “dictated” the question and obscures the fact that Colton Haab submitted it. A CNN spokesperson issued this statement: “The Stand Up: The Students of Stoneman Douglas Demand Action Town Hall was intended to be a forum for students, parents and teachers to speak directly to the elected leaders and stakeholders that are at the center of this critical issue. It is unfortunate that an effort to discredit CNN and the town hall with doctored emails has taken any attention away from the purpose of the event. However, when presented with doctored email exchanges, we felt the need to set the record straight.” “Background” text: Opening statement: page 1 Ladies & gentlemen, lawmakers, fellow students, parents, teachers, faculty – last Wednesday will change our lives forever. My thoughts and prayers are with the victims and their families of this horrific attack on our school. To me, it’s totally incomprehensible how this attacker was able to exit an Uber ride, walk into our freshman building and start shooting. There’s been a lot of talk about Gun Control since this senseless attack. Many of my peers are in Tallahassee with lawmakers now – unfortunately yesterday did not go in the right direction for us. I hope the much needed changes to Gun Laws can be made and implemented by the time the next generation (my kids) enters high school. The way I see it- 3 main things have to happen: 1) Tighten up gun laws 2) Secure the school and make it safe 3) Defend the school I BASED MY QUESTIONS TONIGHT ON #2 & # 3 Question 1) The Number One responsibility of the Federal Government is: To keep Americans safe & secure. We will be called back to school next week … How do we come back if Marjory Stoneman Douglas High School is not safe? Many of us students are afraid to go back until this school is safe & secure. Only 1 School Resource Officer cannot secure a 45 acre campus with multiple entry and exist points. So my 1st question is: What is being done to drastically improve the security of the school? Question 2) page 2 There are armed security defending our President, Congressmen, court houses, IRS buildings, banks, jewelry stores, even the Smithsonian has guards with guns. Yet a gunman walked into our school’s freshman building with a rifle… and hero’s like Coach Fies ….unarmed… died trying to stop him. This is totally unacceptable. Schools are defended with a sign that reads: This is a gun free zone/it might as well also say: (Call someone with a gun if there’s an emergency). It is my opinion and the opinion of many – that this makes us an easy target for evil people to do their evil with little, if any resistance. I personally would much rather see a sign that read: “Please be aware that certain staff members at Marjory Stoneman Douglas are legally armed and may use whatever force necessary to protect our students”. We students should not have to beg to be kept safe. I ask you: are our students’ lives not as significant as court documents? As tax returns? As cash money? As a diamond ring or a fine watch? ARE our lives, our security & safety not as important as old dinosaur bones? My 2nd question is: What measures are being taken to defend our school from future attacks? And how can we get select faculty trained and armed to give them a fighting chance, if GOD forbid, there is another attack? Question 3) page 3 There are over 450,000 unemployed Veterans living in the United States. Many are able, willing & trainable and would find a real purpose in the job of keep our schools safe and defend our students & faculty against evil. What steps can be taken to utilize our select retired military in this capacity? Closing Statement: page 4 President Trump, Governor Scott, Senators Nelson, Rubio and Deutch, Sherriff Israel, Superintendent Runcie, Principle Thompson – I urge you, the student body urges you, our parents urge you: to secure our school. We cannot wait for legislative Gun Law Changes to be approved and implemented. We are going to be called back to school next week. We need Action Now! We have attended way too many funerals this week. We need to make MSD SAFE Now! Secure all Broward schools, secure all Florida Schools and secure all schools across this Nation. The Number One responsibility of the Federal Government is: To keep Americans safe & secure. We students should not have to beg to be kept safe. Please secure our school from outside threats from evil people and give the right people the training & tools needed to defend our lives. It’s time for a change! Don’t let the 17 lives lost last week be just another statistic. Is time to make MSD SAFE! MAKE AMERICA SAFE AGAIN # MSD STRONG Thank you! Read more by Erik Wemple: The ‘scripted’ town-hall question: A CNN non-scandal NRA spokeswoman Dana Loesch: ‘Many in legacy media love mass shootings’ ‘I do not know if the president is having an affair’: Michael Wolff squirms on Dutch TV Ted Cruz says questions from Capitol Hill reporters are ‘never about substance.’ Oh really? CNN makes history with stunning event on gun violence ||||| Marjory Stoneman Douglas High School students and parents wait for a CNN town hall broadcast to begin, Wednesday, Feb. 21, 2018, at the BB&T; Center, in Sunrise, Fla. (Michael Laughlin/South Florida Sun-Sentinel... (Associated Press) Marjory Stoneman Douglas High School students and parents wait for a CNN town hall broadcast to begin, Wednesday, Feb. 21, 2018, at the BB&T; Center, in Sunrise, Fla. (Michael Laughlin/South Florida Sun-Sentinel via AP) (Associated Press) Marjory Stoneman Douglas High School students and parents wait for a CNN town hall broadcast to begin, Wednesday, Feb. 21, 2018, at the BB&T; Center, in Sunrise, Fla. (Michael Laughlin/South Florida Sun-Sentinel via AP) (Associated Press) Marjory Stoneman Douglas High School students and parents wait for a CNN town hall broadcast to begin, Wednesday, Feb. 21, 2018, at the BB&T; Center, in Sunrise, Fla. (Michael Laughlin/South Florida Sun-Sentinel... (Associated Press) The father of a Florida shooting survivor acknowledged Tuesday he omitted words in an email he sent media outlets accusing CNN of using scripted remarks at a town hall on guns and school safety. Dozens of conservative websites called the network's Feb. 21 town hall forum scripted after Marjory Stoneman Douglas High School junior Colton Haab skipped the event and said the network had told him what question to ask. The websites call it proof the forum was slanted against gun rights. President Donald Trump tweeted about it on Friday, saying "Just like so much of CNN, Fake News!" CNN countered with a release of email exchanges between producer Carrie Stevenson, Colton Haab and his father Glenn and accused Glenn Haab of deliberately altering email sent to Fox News and the Huffington Post. "It is unfortunate that an effort to discredit CNN and the town hall with doctored emails has taken any attention away from the purpose of the event," the network said in a statement. Glenn Haab told The Associated Press he omitted some words from the email but said he didn't do it on purpose. "There was nothing malicious behind it," he said. In one exchange, 17-year-old Colton Haab proposes several questions to ask at the town hall, including one on whether to arm teachers. His father, a Republican gun owner, later emailed Stevenson a four-page document with a roughly 700-word speech and a series of questions he said Colton wanted to ask. Stevenson told the father the additional language he proposed was "way too long" and Colton would need to stick to the question "that he submitted." The words "that he submitted" were left off the email sent to Fox News and Huffington Post. CNN said Stevenson had discussed which one of Colton's several questions to ask at the forum and they mutually agreed on one using his own words and a statement he made during another television appearance.

– An emotional CNN town hall last week after the Feb. 14 shooting at Marjory Stoneman Douglas High School focused on gun control and school safety, but the network soon found itself in a tiff with the family of one of the survivors. Conservative outlets went after CNN for "scripting" the event after 17-year-old Colton Haab, who was supposed to take part in the town hall, didn't show because his family says the network was telling him what question to ask, per HuffPost. Even President Trump weighed in, once more calling CNN "fake news." But the AP reports that on Tuesday, Colton's dad, Glenn Haab, fessed up to modifying an email he sent to other media outlets as supposed proof that CNN was trying to tell Colton what to say during the event. CNN had adamantly denied it scripted Colton's, or anyone's, questions for the town hall, but Glenn Haab then sent to Fox News and HuffPost an email between himself, his son, and a CNN producer that was meant to show Colton was being told what question to ask by CNN. But CNN offered up its own version to the Washington Post, which shows the email exchange in its entirety and reveals that Haab's version of one of the emails deleted certain words that made clear the question Colton was cleared to ask was one he'd originally submitted himself. Glenn Haab now tells the AP he did leave out some words from his version of the email, but that "there was nothing malicious behind it." "It is unfortunate that an effort to discredit CNN and the town hall with doctored emails has taken any attention away from the purpose of the event," the network said in a statement.

abdominal tuberculosis ( tb ) is a type of extra - pulmonary tb commonly affecting the intestinal tract , lymph nodes , peritoneum , and solid organs . isolated pancreatic tb is rare and preoperative diagnosis is difficult . as the clinical and radiographic presentation mimics endoscopic ultrasonography guided fine - needle aspiration ( eus - fna ) and f-18 fluoro-2-deoxy - d - glucose positron emission tomography / computed tomography ( fdg pet / ct ) are complimentary , since the latter can help in localizing the region to be aspirated by eus - fna for the diagnosis of peripancreatic tb , avoiding unnecessary surgery for extra hepatic biliary obstruction ( ehbo ) . this case report illustrates how fdg pet / ct imaging can be useful as a noninvasive modality , in conjunction with other clinical and radiological information , in monitoring treatment of extra - pulmonary tb . a 34-year - old asian male presented with jaundice , pruritus , loss of appetite and weight and mild abdominal pain for 3 weeks . abdominal ultrasonography showed a fatty liver with a dilated common bile duct ( cbd ) and intrahepatic biliary radicles with enlarged lymph nodes at the porta hepatis . contrast enhanced ct of the abdomen revealed a heterogeneous soft tissue mass involving the head and uncinate process of the pancreas , cbd and main pancreatic duct , with necrotic lymph nodes at the porta hepatis . the chest x - ray was normal . however , the mantoux test was strongly positive , suggesting mycobacterial infection . intense fdg uptake with a standardized uptake value ( suvmax ) of 23.4 was noted in the pancreatic lesion as well as in enlarged supraclavicular , mediastinal and retro - peritoneal lymph nodes and the marrow of both humeri [ figure 1 ] . the mild symmetrical fdg avidity in the humeri was considered to be due to reactive marrow . the eus - fna specimen from the pancreatic mass showed predominantly necrosis with inflammatory cells and a few ill - formed epithelioid cell granulomas ; stain for acid fast bacilli was positive , leading to a diagnosis of peripancreatic tb . maximum intensity projection ( a ) , axial computed tomography ( ct ) ( b ) and axial fused positron emission tomography / ct ( c ) images of the baseline scan showing increased f-18 fluoro-2-deoxy - d - glucose uptake ( standardized uptake value 23.4 ) in the peripancreatic lesion ( arrowhead ) as well as in enlarged supraclavicular , mediastinal and retro - peritoneal lymph nodes and the marrow of the humeri ( arrows ) three months after the initiation of att , jaundice resolved and the patient reported improvement in symptoms . fdg pet / ct at this time [ figure 2 ] showed complete resolution of the lesion in the pancreatic head and significant reduction in size and fdg avidity of the peripancreatic lymph nodes with reduction of suvmax from 23.4 to 4.7 . there was completion resolution of all other fdg avid foci seen in the baseline scan . the patient completed 6 months course of att and is currently symptom free under follow - up . maximum intensity projection ( a ) , axial computed tomography ( ct ) ( b ) and axial fused positron emission tomography / ct ( c ) images 3 months after starting anti - tubercular treatment , showing complete resolution of the lesions in the pancreatic head and elsewhere . the peripancreatic lymph nodes ( b and c ) show a significant reduction in size and f-18 fluoro-2-deoxy - d - glucose avidity ( standardized uptake value 4.7 ) abdominal tb commonly affects the intestinal tract , lymph nodes , peritoneum and solid organs . the pancreas is relatively resistant to mycobacterial invasion , requiring a large intrapancreatic inoculum of mycobacterium tuberculosis to cause pancreatic lesions . the two postulated routes of spread are directly from involved peripancreatic lymph nodes and more rarely from hematogenous spread . in our patient , the disease in the peripancreatic nodes might have contiguously spread to the pancreatic head , which is sometimes difficult to distinguish radiologically . . findings that may suggest mycobacterial infection include the presence of rim - enhanced lymph nodes in the peripancreatic region or the mesentery , ascites , and a thickened bowel wall in the ileo - cecal region . as the clinical and radiographic presentation mimics endoscopic ultrasonography guided - fna has emerged as a safe and promising method for the diagnosis of peripancreatic tb . song et al . in their study reported 76.2% sensitivity for eus - fna in the diagnosis of pancreatic / peripancreatic tb . usually , the amount of sample acquired by eus - fna is small and could lead to an inconclusive cytological result . fdg pet can help in locating a specific region for aspiration , potentially increasing the yield from this invasive procedure . have demonstrated fdg uptake in pancreatic tb . while our patient showed features of ehbo , the radiological findings were not diagnostic for any specific pathology . however , eus - fna confirmed the diagnosis of pancreatic tb , avoiding unnecessary surgery for ehbo . , some bacillus - negative tuberculomas do not decrease in size or may continue to grow , making it difficult for physicians to decide on alternate treatment regimens . park et al . have showed that fdg pet / ct imaging can be useful in this situation . if the suv increases , it is likely that the tuberculoma is active and treatment needs to be prolonged or the patient switched to other drugs . a decrease in suv would indicate a tuberculoma responsive to att and that current treatment should be continued according to the standard protocol . in an experimental study , serial pulmonary fdg pet was compared with standard microbiological methods to monitor the response to treatment in mice infected with m. tuberculosis aerosol . imaging was available in real time , as opposed to having colony - forming unit counts 4 weeks later ; and could also detect relapse in a time frame similar to that of the standard method . the significant reduction of suvmax in our patient after 3 months of att provided objective evidence of response to the ongoing treatment protocol . patients with hiv have a higher incidence of extrapulmonary tb and in many cases are multi - drug resistant . fdg pet / ct can be used as an ideal treatment - monitoring tool in these patients . we suggest that fdg - pet / ct may provide an important noninvasive means of evaluating therapeutic response in patients with peripancreatic tb .

f-18 fluoro-2-deoxy - d - glucose positron emission tomography / computed tomography ( fdg pet / ct ) is a functional imaging technique that monitors glucose metabolism in tissues . pulmonary tuberculosis ( tb ) has been reported to show intense uptake of fdg , with a decrease in metabolism of the tuberculous lesions after successful anti - tubercular treatment ( att ) . the authors present a patient with pancreatic tb and demonstrate the usefulness of fdg pet / ct in monitoring the response to att .

active research on graphene@xcite revealed not only numerous exceptional properties @xcite but also have prepared a ground for the discovery of several graphene based materials . preparation of freestanding graphene sheets with nonuniform oxygen coverage have been achieved.@xcite more recently the synthesis of two - dimensional hydrocarbon in honeycomb structure , so called _ graphane _ @xcite ( ch ) , showing diverse electronic , magnetic and mechanical properties @xcite is reported . according to pauling scale f has electronegativity of 3.98 , which is higher than those of c(2.55 ) , h(2.20 ) and o(3.44 ) , and hence fluorination of graphene is expected to result in a material , which may be even more interesting than both graphene oxide and ch . before the first synthesis of graphene , fluorinated graphite has been treated theoretically . @xcite owing to promising properties revealed for ch , fluorinated graphene structures are now attracting considerable interest @xcite despite uncertainties in their chemical compositions and atomic structures . in an effort to identify the structures of fluorinated samples , previous theoretical models attempted to deduce the lowest energy structures . @xcite in addition , band gaps of different structures calculated within density functional theory ( dft ) are compared with the values revealed through specific measurements.@xcite however , neither the stability of proposed structures are questioned , nor underestimation of band gaps within dft has been a subject matter . raman spectrum by itself , has been limited in specifying c@xmath0f structures.@xcite in this work , we first determined stable c@xmath0f structures for @xmath1 . then we revealed specific properties ( such as internal structural parameters , elastic constants , formation and binding energies , energy band gap and photoelectric threshold ) for those stable structures as signatures to identify the derivatives probed experimentally . we placed an emphasis on fully fluorinated graphene or fluorographene ( cf ) , in which d and g raman peaks of bare graphene disappear after long fluorination period.@xcite present study reveals that the properties , such as structural parameters , binding energy , band gap and phonon modes of various fluorinated structures are strongly dependent on the binding structure of f atoms and their composition . some of these properties are found to roughly scale with f coverage . while the stable c@xmath2f chair structure is metallic , cf is a nonmagnetic insulator with a band gap , @xmath3 , being much larger than 3 ev , i.e. a value attributed experimentally to fully fluorinated graphene . in view of the calculated diffusion constant , raman active modes and other properties , available experimental data suggest that domains ( or grains ) of various c@xmath0f structures with extended and imperfect grain boundaries can coexist after fluorination process . hence the measured properties are averaged from diverse perfect and imperfect regions . our predictions are obtained from first - principles plane wave calculations@xcite within dft , which is demonstrated to yield rather accurate results for carbon based materials . calculations are performed using spin - polarized local density approximation ( lda)@xcite and projector augmented wave ( paw ) potentials.@xcite kinetic energy cutoff @xmath4 for plane - wave basis set is taken as 500 ev . in the self - consistent potential and total energy calculations of fluorographene a set of ( 25x25x1 ) * k*-point sampling is used for brillouin zone ( bz ) integration . the convergence criterion of self consistent calculations for ionic relaxations is @xmath5 ev between two consecutive steps . by using the conjugate gradient method , all atomic positions and unit cells are optimized until the atomic forces are less than 0.03 ev / . pressures on the lattice unit cell are decreased to values less than 0.5 kbar . the energy band gap , which is usually underestimated in dft , is corrected by frequency - dependent gw@xmath6 calculations.@xcite in gw@xmath6 corrections screened coulomb potential , w , is kept fixed to initial dft value w@xmath6 and green s function , g , is iterated four times . various tests are performed regarding vacuum spacing , kinetic energy cut - off energy , number of bands , * k*-points and grid points . finally , the band gap of cf is found 7.49 ev after gw@xmath6 correction , which is carried out by using ( 12x12x1 ) * k*-points in bz , @xmath7 vacuum spacing , default cut - off potential for gw@xmath6 , 192 bands and 64 grid points . phonon frequencies and phonon eigenvectors are calculated using the density functional perturbation theory ( dfpt).@xcite each carbon atom of graphene can bind only one f atom and through coverage ( or decoration ) of one or two sides of graphene , one can achieve diverse c@xmath8f structures . uniform f coverage is specified by @xmath9 ( namely one f adatom per @xmath10 c atoms ) , whereby @xmath11 corresponds to half fluorination and @xmath12 is fluorographene cf . the adsorption of a single f atom to graphene is precursor for fluorination . when placed at diverse sites of a @xmath13 supercell of graphene , simple f atom moves to the top site of a carbon atom and remains adsorbed there . for the resulting structure spin - polarized state ( with 0.4 bohr magneton ) is only 2 mev favorable than the nonmagnetic state . the binding energy of f is @xmath14=2.71 ev in equilibrium , that is a rather strong binding unlike many other adatoms adsorbed to graphene . an energy barrier , @xmath150.45 ev , occurs along its minimum energy migration path . our calculations related with the minimum energy path of a single f atom follow hexagons of underlying graphene . namely , f atom migrates from the highest binding energy site , i.e. top site ( on top of carbon atom ) to the next top site through bridge site ( bridge position between two adjacent carbon atoms of graphene ) . the corresponding diffusion constant for a single f atom , @xmath16 is calculated in terms of the lattice constant , @xmath17 and characteristic jump frequency @xmath1839 thz . experiments present evidences that energy barriers on the order of 0.5 ev would make the adatoms mobile.@xcite moreover , this energy barrier is further lowered even it is collapsed in the presence of a second f atom at the close proximity . consequently , this situation together with the tendency towards clustering favors that c@xmath0f grains ( or domains ) of different @xmath10 on graphene can form in the course of fluorination . we note that the energy barrier for the diffusion of a single carbon adatom adsorbed on the bridge sites of graphene was calculated to be in the similar energy range . carbon adatoms on graphene were found to be rather mobile . that energy barrier for single c adatom was found to decrease , even to collapse at the close proximity of a second adatom.@xcite f structures calculated along the symmetry directions of bz . carbon and fluorine atoms are indicated by black ( dark ) and blue ( light ) balls , respectively . ( a ) c@xmath2f chair structure . ( b ) c@xmath2f boat structure . ( c ) c@xmath19f structure . units are for structural parameters and @xmath20 for frequencies.,width=321 ] [ cols="<,^,^,^,^,^,^,^,^,^,^,^,^,^,^,^,^ " , ] in earlier theoretical studies , @xcite the total energies and/or binding energies were taken as criteria for whether a given c@xmath0f structure exists . even if a c@xmath0f structure seems to be in a minimum on the born- oppenheimer surface , its stability is meticulously examined by calculating frequencies of all phonon modes in bz . here we calculated phonon dispersions of most of optimized c@xmath0f structures . we found c@xmath19f , c@xmath2f boat , c@xmath2f chair ( see fig . [ fig1 ] ) and cf chair ( see fig . [ fig2 ] ) structures have positive frequencies throughout the brillouin zone indicating their stability . some of phonon branches of c@xmath0f structures ( for example , cf boat ) have imaginary frequencies and hence are unstable , in spite of the fact that their structures can be optimized . the possibility that these unstable structures can occur at finite and small sizes is , however , not excluded . for stable structures , the gap between optical and acoustical branches is collapsed , since the optical branches associated with the modes of c - f bonds occur at lower frequencies . this situation is in contrast with the phonon spectrum of graphane , @xcite where optical modes related with c - h bonds appear above the acoustical branches at @xmath21 2900 @xmath20 . and @xmath22 are the lattice vectors ( @xmath23 ) of hexagonal structure ; @xmath24 ( @xmath25 ) is the c - c ( c - f ) bond distance ; @xmath26 is the buckling . ( b ) phonon frequencies versus wave vector * k * of optimized cf calculated along symmetry directions in bz . ( c ) symmetries , frequencies and descriptions of raman active modes of cf . ( d ) calculated raman active modes of graphene , ch , cf and c@xmath19f are indicated on the frequency axis . those modes indicated by `` + '' are observed experimentally . there is no experimental raman data in the shaded regions . units are for structural parameters and @xmath20 for frequencies.,width=321 ] the formation energy of fluorination is defined as @xmath27 in terms of the total ground state energies of optimized structures of graphene and fluorinated graphenes at different composition , respectively , @xmath28 , @xmath29 , and the total ground state energy of single carbon atom , @xmath30 , of f@xmath2 molecule and f atom , @xmath31 and @xmath32 . similarly , the binding energy of f atom relative to graphene including f - f coupling is @xmath33 and without f - f coupling @xmath34 . here @xmath35 is the total energy of suspended single or double layers of f occupying the same positions as in c@xmath0f . the desorption energy , @xmath36 is the energy required to remove one single f atom from the surface of c@xmath0f . @xmath37 and @xmath38 are numbers of f@xmath2 molecules and f atoms , respectively . the total energies are calculated in periodically repeating supercells comprising 8 carbon atoms and keeping all the parameters of calculations described above using spin - polarized as well as spin unpolarized lda . lowest ( magnetic or nonmagnetic ) total energy is used as ground state total energy . fluorographene ( cf ) , where f atoms are bound to each c atom of graphene alternatingly from top and bottom sides is energetically most favorable structure . upon full fluorination , the planar honeycomb structure of c atoms becomes buckled ( puckered ) and c - c bond length increases by @xmath2110% . at the end , while planar @xmath39-bonding of graphene is dehybridized , the buckled configuration is maintained by @xmath40-like rehybridization . in table [ table ] , the calculated lattice constants , internal structural parameters , relevant binding energies and energy band gaps of stable c@xmath0f structures are compared with those of bare graphene and ch.@xcite notably , internal parameters ( such as @xmath26 , c - c bond length ) as well as lattice constants of various c@xmath0f structures vary with f coverage , @xmath41 . cf , has highest values for @xmath42 , @xmath14 , @xmath43 and @xmath36 given in table [ table ] ; those of c@xmath19f are second highest among stable c@xmath0f structures . since raman spectrum can convey information for a particular structure and hence can set its signature , calculated raman active modes of stable c@xmath19f and cf structures together with those of graphene and ch are also indicated in fig . [ fig2 ] ( c ) and ( d ) . it is known that the only characteristic raman active mode of graphene at 1594 @xmath20 is observed so far . @xcite similarly , for ch the mode at @xmath211342 @xmath20 is observed.@xcite one of two raman active modes of c@xmath19f at 1645 @xmath20 seems to be observed.@xcite in compliance with the theory , @xcite phonon branches of all these observed modes exhibit a kink structure . however , none of the raman active modes of cf revealed in fig . [ fig2 ] has been observed yet . raman spectroscopy in the low frequency range may be useful in identifying experimental structures . energy bands , which are calculated for the optimized c@xmath19f , c@xmath2f boat , c@xmath2f chair and cf chair structures are presented in fig . [ fig3 ] and fig . [ fig4 ] structures , respectively . the orbital projected densities of states ( pdos ) together with the total densities of states of these optimized structures are also presented . analysis of the electronic structure can also provide data to reveal the observed structure of fluorinated graphene . as seen in table [ table ] , stable c@xmath0f structures have lda band gaps ranging from 0 ev to 2.96 ev . surprisingly , c@xmath2f chair structure is found to be a metal owing to the odd number of valance electrons in the primitive unit cell . even if various measurements on the band gap of fluorinated graphene lie in the energy range from 68 mev@xcite to 3 ev,@xcite these calculated band gaps are underestimated by lda . incidentally , the band gaps change significantly after they are corrected by various self - energy methods . in fact , the correction using gw@xmath44 self - energy method predicts a rather wide band gap of 7.49 ev for cf . the corrected band gaps for c@xmath2f boat structure and c@xmath19f are 5.68 ev and 5.99 ev , respectively . it should be noted that the gw@xmath44 self - energy method has been successful in predicting the band gaps of 3d semiconductors.@xcite f structures together with the orbital projected densities of states and the total densities of states ( dos ) . the lda band gaps are shaded and the zero of energy is set to the fermi level @xmath45 . total dos is scaled to 45% . valence and conduction band edges after gw@xmath6 correction are indicated by filled / red circles . ( a ) c@xmath2f chair structure . ( b ) c@xmath2f boat structure . ( c ) c@xmath19f structure.,width=321 ] . valence and conduction band edges after gw@xmath6 correction are indicated by filled / red circles . ( b ) isosurfaces of charge densities of states corresponds to first ( v1 ) , second ( v2 ) valance and first ( c1 ) and second ( c2 ) conduction bands at the @xmath46- and @xmath47-points . ( c ) contour plots of the total charge density @xmath48 and difference charge density @xmath49 in the plane passing through f - c - c - f atoms . contour spacings are 0.03 e / @xmath50.,width=321 ] while predicting much larger band gap for cf , the measured band gap of @xmath213 ev reported by nair et al.@xcite marks the serious discrepancy between theory and experiment . the character of the band structure of cf are revealed from the analysis of projected density of states as well as charge densities of specific bands in fig . [ fig4 ] ( b ) . conduction band edge consists of the antibonding combination of @xmath51-orbitals of f and c atoms . the @xmath51-orbitals of c atoms by themselves , are combined to form @xmath52-bands . the bands at the edge of the valence band are derived from the combination of c-@xmath53 and f-@xmath53 orbitals . the total contribution of c orbitals to the valence band can be viewed as the contribution of four tetrahedrally coordinated @xmath54-like hybrid orbitals of @xmath55- and @xmath56-orbitals of c atoms . however , the deviation from tetrahedral coordination increases when @xmath10 increases or single side is fluorinated . as a matter of fact , the total density of states presented in fig . [ fig3 ] and fig . [ fig4 ] mark crucial differences . in this respect , spectroscopy data is expected to yield significant information regarding the observed structures of fluorinated graphenes . the contour plots of the total charge density , @xmath48 , in the f - c - c - f plane suggests the formation of strong covalent c - c bonds from the bonding combination of two c-@xmath54 hybrid orbitals . the difference charge density , @xmath57 ( which is obtained by subtracting the charges of free c and free f atoms situated at their respective positions in cf ) , indicates charge transfer to the middle of c - c bond and to f atom , revealing the bond charge between c atoms and ionic character of c - f bond . however , the value of charge transfer is not unique , but diversifies among different methods of analysis.@xcite nevertheless , the direction of calculated charge transfer is in compliance with the pauling ionicity scale and is corroborated by calculated born effective charges , which have in - plane ( @xmath58 ) and out - of - plane ( @xmath59 ) components on c atoms , @xmath60 , @xmath61 and on f atoms @xmath62 , @xmath63 . finally , we note that perfect cf is a nonmagnetic insulator . however , a single isolated f vacancy attains a net magnetic moment of 1 bohr magneton ( @xmath64 ) and localized defect states in the band gap . creation of an unpaired @xmath52- electron upon f vacancy is the source of magnetic moment . however , the exchange interaction between two f - vacancies calculated in a ( 7x7x1 ) supercell is found to be nonmagnetic for the first nearest neighbor distances due to spin pairings . similar to graphane,@xcite it is also possible to attain large magnetic moments on f - vacant domains in cf structures . having analyzed the stability of various c@xmath0f structures with @xmath651,2 and 4 , we next investigate their mechanical properties . the elastic properties of this structure can conveniently be characterized by its young s modulus and poison s ratio . however , the in - plane stiffness @xmath66 is known to be a better measure of the strength of single layer honeycomb structures , since the thickness of the layer @xmath67 can not be defined unambiguously . defining @xmath68 as the equilibrium area of a c@xmath0f structures , the in - plane stiffness is obtained as @xmath69 , in terms of strain energy @xmath70 and uniaxial strain @xmath71.@xcite the values of in - plane stiffness @xmath66 , and poisson s ratio @xmath72 , calculated for stable c@xmath0f structures are given in table [ table ] together with the values calculated for graphene and graphane . for example , the calculated values of cf are @xmath66=250 j / m@xmath73 and @xmath72=0.14 . it is noted that @xmath66 increases with @xmath10 . for cf ( i.e. @xmath74 ) , the in - plane stiffness is close to that calculated for ch . it appears that either the interaction between c - f bonds in cf ( or the interaction between c - h bonds in ch ) does not have significant contribution to the in - plane stiffness . the main effect occurs through dehybridization of @xmath39 bonds of graphene through the formation c - f bonds ( or c - h bonds ) . a value of young s modulus around 0.77 @xmath75 can be calculated by estimating the thickness of cf as @xmath67=3.84 , namely the sum of the thickness of graphene ( 3.35 ) and buckling , @xmath26 ( 0.49 ) . this value is smaller , but comparable with the value proposed for graphene , i.e. @xmath21 1 @xmath75 . here the contribution of c - f bonds to the thickness of cf is neglected , since the interaction between c - f bonds has only negligible effects on the strength of cf . in fig . [ figs5 ] the variation of strain energy @xmath70 and its derivative , @xmath76 , with strain , @xmath71 are presented in both elastic and plastic regions . two critical strain values , @xmath77 and @xmath78 , are deduced . the first one , @xmath77 , is the point where the derivative curve attains its maximum value . this means that the structure can be expanded under smaller tension for higher values of strain . this point also corresponds to phonon instability@xcite where the longitudinal acoustic modes start to become imaginary for @xmath79 . the second critical point , @xmath78 @xmath80 ) , corresponds to the yielding point . until this point the honeycomb like structure is preserved , but beyond it the plastic deformation sets in . we note that for @xmath81 the system is actually in a metastable state , where the plastic deformation is delayed . under the long wavelength perturbations , vacancy defects and high ambient temperature @xmath78 approaches to @xmath77 . in fact , our further molecular dynamics simulations show that @xmath82 0.17 at 300k and to 0.16 at 600k . in the presence of periodically repeating f - vacancy and c+f - divacancy , the value of @xmath78 is also lowered to 0.21 and 0.14 , respectively . apart from phonon instability occurring at high @xmath71 , the band gap is strongly affected under uniform expansion . in fig . [ figs5](b ) we show the variation of lda and @xmath83- corrected band gaps under uniform expansion . the lda gap slightly increases until @xmath84 and then decreases steadily with increasing @xmath71 . the @xmath83-corrected band gap essentially decreases with increasing strain . for example , its value decreases by 38% for @xmath85 . present analysis of fluorinated graphenes shows that different c@xmath0f structures can form at different level of f coverage . calculated properties of these structures , such as lattice parameter , @xmath24 distance , band gap , density of states , work function , in plane stiffness @xmath66 , poisson s ratio and surface charge , are shown to depend on @xmath10 or coverage @xmath41 . relevant data reported in various experiments do not appear to agree with the properties calculated any one of the stable c@xmath0f structures . this finding lets us to conclude that domains of various c@xmath0f structures can form in the course of the fluorination of graphene . therefore , the experimental data may reflect a weighted average of diverse c@xmath0f structures together with extended defects in grain boundaries . in this respect , imaging of fluorinated graphene surfaces by scanning tunneling and atomic force microscopy , as well as x - ray photoemission spectroscopy is expected to shed light on the puzzling inconsistency between theory and experiment . finally , our results show a wide range of interesting features of c@xmath0f structures . for example , a perfect cf structure as described in fig . [ fig2 ] is a stiff , nonmagnetic wide band gap nanomaterial having substantial surface charge , but attains significant local magnetic moment through f - vacancy defects . moreover , unlike graphane , half fluorinated graphene with only one side fluorinated is found to be stable , which can be further functionalized by the adsorption of adatoms to other side . for example , hydrogen atoms adsorbed to other side attain positive charge and hence permanent transversal electric field , which can be utilized to engineer electronic properties . this work is supported by tubitak through grant no:108t234 . part of the computational resources has been provided by uybhm at itu through grant grant no . 2 - 024 - 2007 . we thank the deisa consortium ( www.deisa.eu ) , funded through the eu fp7 project ri-222919 , for support within the deisa extreme computing initiative . s. c. acknowledges the partial support of tuba , academy of science of turkey . the authors would also like to acknowledge the valuable suggestions made by d. alfe . j. t. robinson , j. s. burgess , c. e. junkermeier , s. c. badescu , t. l. reinecke , f. k. perkins , m. k. zalalutdniov , j. w. baldwin , j. c. culbertson , p. e. sheehan , and e. s. snow , nano lett . * 10 * , 3001 ( 2010 ) . r. r. nair , w. ren , r. jalil , i. riaz , v. g. kravets , l. britnell , p. blake , f. schedin , a. s. mayorov , s. yuan , m. i. katsnelson , h .- cheng , w. strupinski , l. g. bulusheva , a. v. okotrub , i. v. grigorieva , a. n. grigorenko , k. s. novoselov , a. k. geim , small * 6 * , 2877 ( 2010 ) . hse hybrid functional implemented in vasp [ k. hummer , j. harl , g. kresse , phys . b * 80 * , 115205 ( 2009 ) ] is demonstrated to be as succesful as gw@xmath44 self - energy correction method in predicting the band gaps of bulk 3d crystals . consistently , for 2d honeycomb structures hse is found to yield smaller values than those of gw@xmath6 . for example , while hse predicts the band gap of cf as 4.86 ev , gw@xmath44 gives 7.49 ev . similar trends are also found for ch and 2d boron nitride ( bn ) . hse and gw@xmath6 corrected band gaps of ch ( bn ) band gaps are 4.51 ( 5.74 ) and 5.97 ( 6.86 ) ev , respectively . for example , bader [ g. henkelman , a. arnaldsson , h. jonsson , comput . sci.*36 * , 254 - 360 ( 2006 ) ] , lwdin [ p .- o . lwdin , j. chem . 18 , 365 ( 1950 ) ] and mulliken [ r. s. mulliken , j. chem . phys . * 23 * , 1841 ( 1955 ) ] methods predict charge transfer from c to f atoms , respectively , 0.59 , 0.19 and 0.06 electrons . further analysis by calculating planarly averaged charge density of cf and of free c and f atoms , where the charge due to the tails of orbitals are carefully accounted deduces that the total of 0.11 electrons are transferred from buckled graphene to each f atom .

recent synthesis of fluorinated graphene introduced interesting stable derivatives of graphene . in particular , fluorographene ( cf ) , namely fully fluorinated chair conformation , is found to display crucial features , such as high mechanical strength , charged surfaces , local magnetic moments due to vacancy defects and a wide band gap rapidly reducing with uniform strain . these properties , as well as structural parameters and electronic densities of states are found to scale with fluorine coverage . however , most of the experimental data reported to date neither for cf , nor for other c@xmath0f structures complies with the results obtained from first - principles calculations . in this study , we attempt to clarify the sources of disagreements .

the twin - beam state ( twb ) of two modes of radiation can be expressed in the photon number basis as @xmath0 where @xmath1 , @xmath2 being the twb squeezing parameter . twb is described by a gaussian wigner function @xmath3 with @xmath4 and @xmath5 . since ( [ twb : wig ] ) is positive - definite , twb are not suitable to test nonlocality through homodyne detection . indeed , the wigner function itself provides an explicit hidden variable model for homodyne measurements @xcite . on the other hand , it has been shown @xcite that twb exhibits a nonlocal character for parity measurements . this is known as nonlocality in the phase - space since bell inequalities can be written in terms of the wigner function , which in turn describes correlations for the joint measurement of displaced parity operators . overall , the positivity or the negativity of the wigner function has a rather weak relation to the locality or the nonlocality of quantum correlations . in ref . @xcite we have suggested a conditional measurement scheme on twb leading to a non gaussian entangled mixed state , which improves fidelity in the teleportation of coherent states . this process , called inconclusive photon subtraction ( ips ) , is based on mixing each mode of the twb with the vacuum in a unbalanced beam splitter and then performing inconclusive photodetection on both modes , _ i.e. _ revealing the reflected beams without discriminating the number of the detected photons . a single mode version of the ips , mapping squeezed light onto non - gaussian states , has been recently realized experimentally @xcite . moreover , ips has been suggested as a feasible method to modify twb and test nonlocality using homodyne detection @xcite . in this paper we address ips as a _ degaussification _ map for twb , give its explicit expression for the density matrix and the wigner function , and investigate the nonlocality of the resulting state in the phase - space . the paper is structured as follows . in section [ s : bana ] we review nonlocality in the phase - space , _ i.e. _ wigner function bell s inequality based on measuring the displaced parity operator on two modes of radiation . in section [ s : degauss ] we illustrate the ips process as a degaussification map and calculate the wigner function of the ips state . the nonlocality of the ips state in the phase - space is then analyzed in section [ s : nonlocal ] , whereas in section [ s : homodyne ] we discuss nonlocality using homodyne detection , extending the analysis of ref . @xcite . section [ s : remarks ] closes the paper with some concluding remarks . the displaced parity operator on two modes is defined as @xmath6 where @xmath7 , @xmath8 and @xmath9 are mode operators and @xmath10 and @xmath11 are single - mode displacement operators . parity is a dichotomic variable and thus can be used to establish bell - like inequalities @xcite . since the two - mode wigner function @xmath12 can be expressed as @xmath13 @xmath14 being the expectation value of @xmath15 , the violation of these inequalities is also known as nonlocality in the phase - space . the quantity involved in such inequalities can be written as follows @xmath16 which , for local theories , satisfies the condition @xmath17 . following ref . @xcite , one can choose a particular set of displaced parity operators , arriving at the following combination @xmath18 which only depends on the positive parameter @xmath19 , characterizing the magnitude of the displacement . if we evaluate the quantity ( [ bell : bana ] ) in the case of the twb , we find that it exceeds the upper bound imposed by local theories for a certain region of values @xmath20 , its maximum being @xmath21 @xcite . on the other hand , the choice of the parameters leading to eq . ( [ bell : bana ] ) is not the best one , and the violation of the inequality @xmath17 can be enhanced using a different parameterization @xcite . a better result is achieved for @xmath22 which , for the twb , gives a maximum @xmath23 , greater than the value @xmath24 obtained in ref . @xcite . in the following sections we will see that the violation of the inequalities @xmath25 and @xmath26 can be enhanced by degaussification of the twb . the degaussification of a twb can be achieved by subtracting photons from both modes @xcite . in ref . @xcite we referred to this process as to inconclusive photon subtraction and showed that the resulting state , the ips state @xmath27 , can be used to enhance the teleportation fidelity of coherent states for a wide range of the experimental parameters . scheme of the ips process . ] the ips scheme is sketched in fig . [ f : ips : scheme ] . the two modes , @xmath8 and @xmath9 , of the twb are mixed with the vacuum ( modes @xmath28 and @xmath29 , respectively ) at two unbalanced beam splitters ( bs ) with equal transmissivity @xmath30 ; the modes @xmath28 and @xmath29 are then revealed by avalanche photodetectors ( apd ) with equal efficiency @xmath31 . apd s can only discriminate the presence of radiation from the vacuum . the positive operator - valued measure ( povm ) @xmath32 of each detector is given by @xmath33 @xmath31 being the quantum efficiency . overall , the conditional measurement on the modes @xmath28 and @xmath29 , is described by the povm ( we are assuming the same quantum efficiency for both photodetectors ) @xmath34 when the two photodetectors jointly click , the conditioned output state of modes @xmath8 and @xmath9 is given by @xmath35\ : , \label{ptr}\end{aligned}\ ] ] where @xmath36 and @xmath37 are the evolution operators of the beam splitters and @xmath38 the density operator of the two - mode state entering the beam splitters ( in our case latexmath:[$r = \varrho_{\hbox{\tiny twb } } = partial trace on modes @xmath28 and @xmath29 can be explicitly evaluated , thus arriving at the kraus decomposition of the ips map . we have @xmath40 with @xmath41}{p!}}\,,\ ] ] and @xmath42 and @xmath43\end{aligned}\ ] ] is the probability of a click in both detectors . now , in order to investigate the nonlocality of the state @xmath44 in the phase - space , we explicitly calculate its wigner function , which , as one may expect , is no longer gaussian and positive - definite . the state entering the two beam splitters is described by the wigner function @xmath45 where the second factor at the rhs represents the two vacuum states of modes @xmath28 and @xmath29 . the action of the beam splitters on @xmath46 can be summarized by the following change of variables @xmath47 and the output state , after the beam splitters , is then given by @xmath48 where @xmath49 and @xmath50,\\ w & \equiv & w(r,\phi ) = 2 \cos\phi\ , \sin\phi\ , [ ( 1-a){\overline{\beta}}+ b \alpha]\,.\end{aligned}\ ] ] at this stage conditional on / off detection is performed on modes @xmath28 and @xmath29 ( see fig . [ f : ips : scheme ] ) . we are interested in the situation when both the detectors click . the wigner function of the double click element @xmath51 of the povm ( see eq . ( [ povm11 ] ) ) is given by @xcite @xmath52(\zeta,\xi)\nonumber\\ & = & \frac{1}{\pi^2}\ { 1-q_{\eta}(\zeta)-q_{\eta}(\xi)\nonumber\\ & \mbox{}&\hspace{1.5 cm } + q_{\eta}(\zeta ) q_{\eta}(\xi ) \}\,,\end{aligned}\ ] ] with @xmath53 using eq . ( [ ptr ] ) and the phase - space expression of trace ( for each mode ) @xmath54 = \pi\ , \int_{\mathbb{c } } d^2 z\ , w[o_1](z)\ , w[o_2](z)\,,\ ] ] @xmath55 and @xmath56 being two operators and @xmath57(z)$ ] and @xmath58(z)$ ] their wigner functions , respectively , the wigner function of the output state , conditioned to the double click event , is then given by @xmath59 where @xmath60 and @xmath61 is the double - click probability ( [ dc : fock ] ) , which can be written as function of @xmath62 as follows @xmath63 the quantity @xmath64 appearing in eq . ( [ w : ips : informal : f ] ) is @xmath65 and the expressions of @xmath66 , @xmath67 and @xmath68 are given in table [ t : jj ] . .[t : jj ] [ cols="^,^,^,^",options="header " , ] the mixing with the vacuum in a beam splitter with transmissivity @xmath69 followed by on / off detection with quantum efficiency @xmath31 is equivalent to mixing with an effective transmissivity @xcite @xmath70 followed by an ideal ( _ i.e. _ efficiency equal to 1 ) on / off detection . therefore , the state ( [ w : ips : informal ] ) can be studied for @xmath71 and replacing @xmath69 with @xmath72 . thanks to this substitution , after the integrations we have @xmath73 and @xmath74^{-1 } c_j(\eta ) } { ( b - f_j)(b - g_j)-(2 b h_j \tau_{\rm eff})^2 } \,,\ ] ] where we defined @xmath75\,,\\ g_j & \equiv & g_j(r,\phi,\eta ) = n_j \ , [ x_j b^2 + 4 b^2 ( 1-a ) ( 1-\tau_{\rm eff } ) + y_j ( 1-a)^2]\,,\\ h_j & \equiv & h_j(r,\phi,\eta ) = n_j \ , [ ( x_j + y_j ) b ( 1-a ) + 4 b ( b^2 + ( 1-a)^2 ) ( 1-\tau_{\rm eff})]\,,\\ n_j & \equiv & n_j(r,\phi,\eta ) = { \displaystyle \frac{4 \tau_{\rm eff}\ , ( 1-\tau_{\rm eff})}{x_j y_j - 4 b^2 ( 1-\tau_{\rm eff})^2}\ , . } \end{aligned}\ ] ] in this way , the wigner function of the ips state can be rewritten as @xmath76}\,,\end{aligned}\ ] ] where we introduced @xmath77 the state given in eq . ( [ ips : wigner ] ) is no longer a gaussian state . in this section we investigate the nonlocality of the state ( [ ips : wigner ] ) in phase - space using the quantity @xmath78 given in eq . ( [ bell : general ] ) , referring to both the parameterizations @xmath79 ( see eq . ( [ bell : bana ] ) ) and @xmath80 ( see eq . ( [ bell : ale ] ) ) . plot of @xmath79 given in eq . ( [ bell : bana ] ) for @xmath81 . the dashed line is @xmath82 , while the solid lines are @xmath83 for different values of @xmath72 ( see the text ) : from top to bottom @xmath84 and @xmath85 . when @xmath86 , the maximum of @xmath87 is @xmath88 . the lower plot is a magnification of the region @xmath89 of the upper one . notice that for small @xmath2 there is always a region where @xmath90 . ] plots of @xmath79 given in eq . ( [ bell : bana ] ) as a function of the squeezing parameter @xmath2 for different values of @xmath19 : ( a ) @xmath91 , ( b ) @xmath92 and ( c ) @xmath93 . in all the plots the dashed line is @xmath82 , while the solid lines are @xmath83 for different values of @xmath72 ( see the text ) : from top to bottom @xmath94 and @xmath95 . notice that there is always a region for small @xmath2 where @xmath90 . when @xmath96 the maximum of @xmath83 is always greater than the one of @xmath82 . ] as for a twb , the violation of the bell s inequality is observed for small @xmath2 @xcite . from now on , we will refer to @xmath79 as @xmath82 when it is evaluated for a twb ( [ twb : wig ] ) , and as @xmath83 when we consider the ips state ( [ ips : wigner ] ) . we plot @xmath82 and @xmath97 in the figs . [ f : ips : vs : twb : j ] and [ f : ips : vs : twb ] for different values of the effective transmissivity @xmath72 and of the parameter @xmath19 : for not too big values of the squeezing parameter @xmath2 , one has that @xmath98 . moreover , when @xmath72 approaches unit , _ i.e. _ when at most one photon is subtracted from each mode , the maximum of @xmath99 is always greater than the one obtained using a twb . a numerical analysis shows that in the limit @xmath100 the maximum is @xmath101 , that is greater than the value @xmath24 obtained for a twb @xcite . the limit @xmath100 corresponds to the case of one single photon subtracted from each mode @xcite . notice that increasing @xmath19 reduces the interval of the values of @xmath2 for which one has the violation . for large @xmath2 the best result is thus obtained with the twb since , as the energy grows , more photons are subtracted from the initial state @xcite . since the relevant parameter for violation of bell inequalities is @xmath72 , we have , from eq . ( [ taueff ] ) , that the ips state is nonlocal also for low quantum efficiency of the ips detector . plots of @xmath80 given in eq . ( [ bell : ale ] ) as a function of the squeezing parameter @xmath2 for @xmath102 . in all the plots the dashed line is @xmath103 , while the solid lines are @xmath104 for different values of @xmath72 ( see the text ) : from top to bottom @xmath105 and @xmath106 . when @xmath96 the maximum of @xmath104 is @xmath107 . ] the same conclusions holds when we consider the parameterization of eq . ( [ bell : ale ] ) . in fig . [ f : ips : ale ] we plot @xmath103 and @xmath108 , _ i.e. _ @xmath80 evaluated for the twb and the ips state , respectively . the behavior is similar to that of @xmath79 , the maximum violation being now @xmath109 for @xmath96 and @xmath110 . finally , notice that the maximum violation using ips states is achieved ( for both parameterizations ) when @xmath72 approaches unit and for values of @xmath2 smaller than for twb . the wigner function @xmath111 given in eq . ( [ ips : wigner ] ) is not positive - definite and thus @xmath112 can be used to test the violation of bell s inequalities by means of homodyne detection , _ i.e. _ measuring the quadratures @xmath113 and @xmath114 of the two ips modes @xmath8 and @xmath9 , respectively , as proposed in ref . @xcite . in this case , if one discretizes the measured quadratures assuming as outcome @xmath115 when @xmath116 , and @xmath117 otherwise , one obtains the following bell parameter @xmath118 where @xmath119 and @xmath120 are the phases of the two homodyne measurements at the modes @xmath8 and @xmath9 , respectively , and @xmath121\ , p(x_{\vartheta_j } , x_{\varphi_k})\,,\ ] ] @xmath122 being the joint probability of obtaining the two outcomes @xmath123 and @xmath124 @xcite . as usual , violation of bell s inequality is achieved when @xmath125 . in fig . [ f : homo : id ] we plot @xmath126 for @xmath127 , @xmath128 , @xmath129 and @xmath130 : as pointed out in ref . @xcite , the bell s inequality is violated for a suitable choice of the squeezing parameter @xmath2 . notice that when @xmath72 decreases the maximum of violation shifts toward higher values of @xmath2 . as one expects , taking into account the efficiency @xmath131 of the homodyne detection furtherly reduces the violation ( see fig . [ f : homo : eta ] ) . notice that , when @xmath132 , violation occurs for higher values of @xmath2 , although its maximum is actually reduced : in order to have a significative violation one needs a homodyne efficiency greater than 80% ( when @xmath133 ) . plots of @xmath126 given in eq . ( [ bell : homo ] ) as a function of @xmath134 for different values of @xmath72 and for ideal homodyne detection ( _ i.e. _ with quantum efficiency @xmath135 ) : from top to bottom @xmath136 and @xmath137 . ] plots of @xmath126 given in eq . ( [ bell : homo ] ) as a function of @xmath134 with @xmath138 and for different values of the homodyne detection efficiency @xmath131 : from top to bottom @xmath139 and @xmath140 . the maximum of the violation decreases and shifts toward higher values of @xmath2 as @xmath131 decreases . for smaller values of @xmath72 the violation is furtherly reduced . ] in this paper we have shown that ips can be used to produce non - gaussian two - mode states starting from a twb . we have studied the nonlocality of ips states in phase - space using the wigner function . as for the improvement of ips assisted teleportation @xcite , we have found that the nonlocal correlations are enhanced for small energies of the twb ( small squeezing parameter @xmath2 ) . moreover , nonlocality of @xmath27 is larger than that of twb irrespective of ips quantum efficiency . since the wigner function of the ips state is not positive definite , we have also analyzed its nonlocality using homodyne detection . in this case violation of bell s inequality is much less than in the phase - space , and is furtherly reduced for non unit homodyne efficiency @xmath132 . however , this setup ( ips with homodyning ) is of particular interest , since it can be realized with current technology achieving a loophole - free test of bell s inequality @xcite . on the other hand , the experimental verification of phase - space nonlocality is challenging , due to the difficulties of measuring the parity , either directly or through the measurement of the photon distribution . on the other hand , the recent experimental generation of ips states @xcite is indeed a step toward its implementation . so would like to express his gratitude to a. r. rossi and a. ferraro for stimulating discussions and for their continuous assistance . 99 k. banaszek and k. wdkiewicz , phys . a * 58 * , 4345 ( 1998 ) . r. garca - patrn snchez et al . , quant - ph/0403191 . s. olivares , m. g. a. paris and r. bonifacio , phys . rev . a * 67 * , 032314 ( 2003 ) . j. wenger , r. tualle - brouri and p. grangier , phys . rev . lett . * 92 * , 153601 ( 2004 ) . j. f. clauser , m. a. horne , a. shimony and r. a. holt , phys . * 23 * , 880 ( 1969 ) . a. ferraro , private communication . t. opatrn , g. kurizki and d .- welsch , phys . a * 61 * , 032302 ( 2000 ) . p. t. cochrane , t. c. ralph and g. j. milburn , phys . rev . a * 65 * , 062306 ( 2002 ) . m. g. a. paris , m. cola and r. bonifacio , phys . a * 67 * , 042104 ( 2003 ) .

we show that inconclusive photon subtraction ( ips ) on twin - beam produces non - gaussian states that violate bell s inequality in the phase - space . the violation is larger than for the twin - beam itself irrespective of the ips quantum efficiency . the explicit expression of ips map is given both for the density matrix and the wigner function representations .

electronic structure calculations for small molecules can be performed with very good accuracy using quantum chemistry methods . @xcite however , the computational cost rises strongly with the number of valence electrons , and macromolecules with hundreds of delocalized valence electrons can not be treated using accurate ab - initio quantum chemistry methods . in such a situation , models with adjustable parameters are analyzed to describe the ground state and excited states approximately . @xcite an example are @xmath7-conjugated polymers such as polyacetylene ( pa ) or polydiacetylene ( pda ) . typically , the backbone made of @xmath5-bonds is treated in the adiabatic approximation , and only the @xmath7-electrons are included explicitly in the many - particle model . @xcite the electrons itineracy is described by the hckel ( tight - binding ) hamiltonian , and their coulomb repulsion is approximated by the pariser - parr - pople ( ppp ) interaction . recently , we reproduced the optical properties of pda using a tight - binding model with a hubbard - ohno parameterization of the ppp interaction between the @xmath7 electrons . @xcite however , the applicability of hckel - ppp models for @xmath7-conjugated systems has been put into question @xcite because the ppp model only includes density - type interactions and ignores bond - charge repulsion terms that could be important for polymers ; for a thorough discussion , see refs . another point at issue in conjugated polymers is the size of the ` spring constant ' @xmath13 that parameterizes the strength of the @xmath5-bond . in ref . [ ] , the value @xmath14 was proposed for pa , close to the value for the carbon - carbon bond in ethane , @xmath15 at bond length @xmath16 . @xcite in contrast , in ref . [ ] a substantially larger value , @xmath17 , was put forward , closer to empirical values for benzene , @xmath18 with bond length @xmath19 . @xcite the larger value is related to the tendency of bonds to become stiffer at smaller atomic distances , @xcite and the average bond length in polyacetylene is the same as that in benzene . @xcite c@xmath1ch@xmath0 ) , @xmath6 , ethene ( h@xmath2c@xmath3ch@xmath2 , ethylene ) , @xmath8 , and ethyne ( hc@xmath4ch , acetylene ) , @xmath9 , as a function of the carbon - carbon distance @xmath20 in units of . the energies are shifted by their values at the energy minimum . the carbon - hydrogen bonds are fixed at their positions for the equilibrium structure.[fig : potentials ] ] @cc@ ( a ) & ( b ) + @ll@ + @xmath20/ & @xmath21 + + 1.0000 & 10.8084 + 1.0500 & 7.89061 + & + & + 1.2000 & 2.68283 + & + 1.2500 & 1.74053 + 1.3000 & 1.06070 + & + 1.3500 & 0.58770 + 1.4000 & 0.27742 + 1.4500 & 0.09475 + 1.5000 & 0.01163 + 1.5290 & 0 + 1.5500 & 0.00563 + 1.6000 & 0.05877 + 1.6500 & 0.15668 + 1.7000 & 0.28788 + 1.7500 & 0.44322 + 1.8000 & 0.61542 + 1.8500 & 0.79872 + 1.9000 & 0.98856 + 1.9500 & 1.18131 + 2.0000 & 1.37414 & @ll@ + @xmath20/ & @xmath22 + + 1.0000 & 6.56351 + 1.0500 & 4.25500 + 1.1000 & 2.60229 + 1.1500 & 1.45774 + 1.2000 & 0.70626 + & + 1.2500 & 0.25796 + 1.3000 & 0.04249 + 1.3372 & 0 + 1.3500 & 0.00464 + 1.4000 & 0.10095 + 1.4500 & 0.29714 + 1.5000 & 0.56612 + & + 1.5500 & 0.88651 + 1.6000 & 1.24145 & @ll@ + @xmath20/ & @xmath23 + + 1.0000 & 3.42482 + 1.0500 & 1.78346 + 1.1000 & 0.75783 + 1.1500 & 0.20269 + 1.2000 & 0.00484 + 1.2097 & 0 + 1.2500 & 0.07592 + 1.3000 & 0.34680 + & + 1.3500 & 0.76329 + 1.4000 & 1.28284 + 1.4500 & 1.87198 + & @ll@ + @xmath20/ & @xmath21 + + 1.0000 & 11.3730 + 1.0500 & 8.31871 + & + & + 1.2000 & 2.84798 + & + 1.2500 & 1.85257 + 1.3000 & 1.13216 + & + 1.3500 & 0.62916 + 1.4000 & 0.29792 + 1.4500 & 0.10209 + 1.5000 & 0.01258 + 1.5290 & 0 + 1.5500 & 0.00609 + 1.6000 & 0.06391 + 1.6500 & 0.17101 + 1.7000 & 0.31534 + 1.7500 & 0.48722 + 1.8000 & 0.67891 + 1.8500 & 0.88423 + 1.9000 & 1.09820 + 1.9500 & 1.31686 + 2.0000 & 1.53703 & @ll@ + @xmath20/ & @xmath22 + + 1.0000 & 6.68729 + 1.0500 & 4.33523 + 1.1000 & 2.65165 + 1.1500 & 1.48570 + 1.2000 & 0.72002 + & + 1.2500 & 0.26309 + 1.3000 & 0.04336 + 1.3372 & 0 + 1.3500 & 0.00474 + 1.4000 & 0.10310 + 1.4500 & 0.30366 + 1.5000 & 0.57893 + & + 1.5500 & 0.90718 + 1.6000 & 1.27127 & @ll@ + @xmath20/ & @xmath23 + + 1.0000 & 3.42561 + 1.0500 & 1.78388 + 1.1000 & 0.75802 + 1.1500 & 0.20275 + 1.2000 & 0.00485 + 1.2097 & 0 + 1.2500 & 0.07594 + 1.3000 & 0.34691 + & + 1.3500 & 0.76358 + 1.4000 & 1.28340 + 1.4500 & 1.87290 + apparently , hckel - ppp models can also be applied to small molecules with @xmath7 bonds so that the applicability and accuracy of the model description can be tested against results from quantum chemistry . in this work , we use the two - site hubbard model to describe the @xmath7-bonds in ethene ( h@xmath2c@xmath3ch@xmath2 ) , and ethyne ( hc@xmath4ch ) . we find that the hckel approach provides a reasonably accurate description of the @xmath7-bonds . the application to trans - pa shows , however , that some adjustments in the @xmath5-bond spring constant are necessary to reproduce the experimentally observed bond lengths . our work is organized as follows . in sect . [ sec : potentials ] we use data from quantum chemistry calculations to express the ground - state energies @xmath6 , @xmath8 , and @xmath9 for @xmath5-bonds and @xmath7-bonds in ethane , ethene , and ethyne . in sect . [ sec : hhomodel ] we use the hckel hubbard - ohno hamiltonian to model the energy of the @xmath7-bonds in ethene and ethyne . we shall see that this is possible with an accuracy of about 5% . however , the hubbard - ohno parameters for the coulomb interaction remain essentially undetermined . in sect . [ sec : paapplication ] , to test and adjust our parameter set , we determine the bond lengths and the energies of elementary electronic excitations in trans - pa . short conclusions , sect . [ sec : conclusions ] , close our presentation . we employ the quantum chemistry code molpro @xcite using the ccsd(t ) method with the cc - pvtz basis . @xcite we calculate the energy of the molecules ethane ( h@xmath0c@xmath1ch@xmath0 ) , ethene ( a.k.a . ethylene , h@xmath2c@xmath3ch@xmath2 ) , and ethyne ( a.k.a . acetylene , hc@xmath4ch ) as a function of the carbon - carbon distance @xmath20 . the data for the energies are listed in table [ tab : qcdata ] . similar calculations have been done recently for ethyne , @xcite and for c@xmath2h@xmath24 for @xmath25 . @xcite we can ( a ) choose to relax the whole molecule , or ( b ) to fix the carbon - hydrogen bonds at their positions for the equilibrium structure . the data from quantum chemistry in table [ tab : qcdata ] show that the changes are marginal for ethyne and still very small for ethene . this could be expected because the carbon - hydrogen bonds in the corresponding linear / planar structures do not interfere when we stretch or shrink the carbon - carbon bond . for ethane with its three - dimensional structure , however , the discrepancies in energy are noticeable . since we are interested in the properties of the @xmath5-bond , we later use the data for fixed carbon - hydrogen bonds and plot the corresponding energies from table [ tab : qcdata](b ) as a function of distance in fig . [ fig : potentials ] . @cc@ ( a ) & ( b ) + @lr@ + @xmath26 & [ ev / @xmath27 + + @xmath28 & 26.3496 + @xmath29 & @xmath169.9253 + @xmath30&104.1792 + @xmath31&@xmath1119.1238 + @xmath32 & 105.2503 + @xmath33 & @xmath170.7506 + @xmath34 & 135.5519 + @xmath35 & @xmath1146.0841 + @xmath36&@xmath186.5683 & @lr@ + @xmath37 & [ ev / @xmath27 + + @xmath38&57.4115 + @xmath39 & @xmath1162.4340 + @xmath40 & 259.2015 + @xmath41 & @xmath1336.1312 + @xmath42 & 284.6613 + @xmath43 & @xmath1116.8712 + @xmath44 & 816.7895 & @lr@ + @xmath45 & [ ev / @xmath27 + + @xmath46&101.0452 + @xmath47 & @xmath1294.7982 + @xmath48 & 482.5564 + @xmath49 & @xmath1 656.0314 + @xmath50 & 664.8695 + & @lr@ + @xmath26 & [ ev / @xmath27 + + @xmath28 & 28.5307 + @xmath29 & @xmath172.8851 + @xmath30&106.8931 + @xmath31&@xmath1122.0097 + @xmath32 & 111.0721 + @xmath33 & @xmath181.3086 + @xmath34 & 131.5314 + @xmath35 & @xmath1136.7223 + @xmath36&@xmath5163.3005 & @lr@ + @xmath37 & [ ev / @xmath27 + + @xmath38 & 58.5984 + @xmath39 & @xmath1164.9132 + @xmath40 & 263.5307 + @xmath41 & @xmath1342.9333 + @xmath42 & 296.9368 + @xmath43 & @xmath1141.5545 + @xmath44 & 815.7742 & @lr@ + @xmath45 & [ ev / @xmath27 + + @xmath46 & 101.0741 + @xmath47 & @xmath1294.8085 + @xmath48 & 482.7707 + @xmath49 & @xmath1656.2767 + @xmath50 & 664.6464 + first , we compare the bond lengths with the experimental data . we find for ethane ( one @xmath5-bond ) , ethene ( one @xmath5-bond plus one @xmath7-bond ) , and ethyne ( one @xmath5-bond plus two @xmath7-bonds ) , @xmath52}\ , , \\ r_{\sigma\pi}^{\rm exp}&= & 1.3390\ , \hbox{\aa } \quad \hbox{[\onlinecite{herzberg}]}\ , , \\ r_{\sigma\pi\pi}^{\rm exp}&= & 1.203\hphantom{0}\ , \hbox{\aa } \quad \hbox{[\onlinecite{lievin}]}\ , , \end{array}\ ] ] in very good agreement with the experimental values , with deviations of less than 0.5% . next , we express the energies @xmath53 as a taylor series around the equilibrium distances @xmath54 , @xmath55 where @xmath56 for the three molecules , and @xmath57 is independent of @xmath20 . in the following , we focus on the force fields @xmath58 , @xmath59 because they enter the optimization equations . the parameter sets for ethane , ethene , and ethyne are collected in table [ tab : kvalues ] . one of the vibrational modes in ethane , ethene , and ethyne with reciprocal wave length ( wave number ) @xmath60 can be assigned to a bare carbon - carbon stretch mode . they can be compared to the values from quantum - chemistry calculations , @xmath61}\ , , \\ 1/\lambda^{\rm exp}_{\sigma\pi}&= & 1623\hphantom{.}\ , { \rm cm}^{-1 } \quad \hbox{[\onlinecite{krasser}]}\ , , \\ 1/\lambda^{\rm exp}_{\sigma\pi\pi}&= & 1974\hphantom{.}\ , { \rm cm}^{-1 } \quad \hbox{[\onlinecite{fastwelsh } ] } \ , . \end{array } \label{eq : thelambdas}\ ] ] the experimental values in eq . ( [ eq : thelambdas ] ) are in very good agreement with the results from quantum chemistry , with deviations of less than 3% . this is the desired accuracy of the fit to a hckel hubbard - ohno model . the normal - mode frequencies given in eq . ( [ eq : thelambdas ] ) correspond to vibrational modes that involve the movement of all atoms in the molecule . instead , one may want to invoke a simpler oscillator model with fixed carbon - hydrogen bonds , a single force constant @xmath62 , and an effective mass @xmath63 ( atomic mass unit : @xmath64 ; @xmath65 for ethane , ethene , ethyne ) . @xcite then , the force constant obeys @xmath66 a fit to the experimental data for ethane , ethene , and ethyne then leads to @xmath67 where we used @xmath68 for the conversion of units . the comparison shows that oscillator models with a single ` spring constant ' shall employ values @xmath69 that deviate from the bare values @xmath70 from quantum chemistry calculations by 10%15% . we model a @xmath7-bond by a two - site single - orbital hckel hubbard - ohno model , @xmath72 where @xmath73 ( @xmath74 ) creates ( annihilates ) an electron with spin @xmath75 on carbon atom @xmath76 . moreover , @xmath77 counts the number of @xmath5-electrons on carbon atom @xmath78 and @xmath79 . we assume that the @xmath5-bond is rigid and contributes the potential @xmath6 to the energy . the hamiltonian parametrically depends on the distance @xmath20 between the carbon atoms . the electron transfer parameter decreases exponentially as a function of distance , @xmath80 with @xmath81 at distance @xmath82 . the strength of the peierls coupling @xmath83 and the values for the coulomb interaction @xmath84 and @xmath85 are fit parameters . the distance - dependence of the density - density interaction is given by the ohno expression @xcite @xmath86 the ohno form guarantees that , at large distances , the electrons interact via their unscreened coulomb interaction , @xmath87 . + , @xmath88 due to the @xmath7-bonds in ethene and in ethyne for carbon distances @xmath89 . the force function differences are not the same , they deviate from each other by about @xmath90 for @xmath89 , as seen in the inset . the dashed lines show the fit from the hckel model , @xmath91 and from the hckel hubbard - ohno model , @xmath92 . [ fig : forcefields],title="fig:",width=283 ] the ground - state energy of the hckel hubbard - ohno model is denoted by @xmath93 . the two - site model is readily diagonalized , @xcite @xmath94 ^ 2 } \ ; . \label{eq : esigmapi}\ ] ] up to a constant energy shift , @xmath95 defines the hckel hubbard - ohno approximation to the energy function for ethene , @xmath8 . for ethyne , we further assume that the two @xmath7-bonds are independent of each other . an explicit calculation of the ground - state energy of a two - site model with four orbitals per site shows that , for moderate coulomb interactions , the ground - state energy can indeed be approximated as the sum of two independent two - orbital models . therefore , the hckel hubbard - ohno approach predicts @xmath96 the quality of this hypothesis can be tested by comparing the corresponding differences in the force functions , @xmath97 and @xmath88 . in fig . [ fig : forcefields ] we show the two force function differences @xmath98 for carbon - carbon distances @xmath99 . as is seen from the inset , they differ by about @xmath100 . similarly , the hckel force field @xmath101 at @xmath102 and the hckel hubbard - ohno force field @xmath103 at @xmath104 and @xmath105 deviate from @xmath98 by several tenth of an @xmath106 . since @xmath98 is of the order of @xmath107 , the hckel hubbard - ohno description of the @xmath7-bonds in ethene and ethyne is accurate within a few percent which is of the same order of magnitude as the accuracy of the quantum chemistry data for the vibrational frequencies . therefore , the hckel hubbard - ohno description is accurate enough to match the quality of the quantum chemistry data . for a further improvement , one may refine the expression ( [ eq : peierlstofr ] ) for the distance - dependence of the electron transfer parameter . @xcite since the force functions @xmath98 differ , we can not determine @xmath93 from eq . ( [ eq : testhueckel ] ) as the difference between @xmath6 and @xmath8 . instead , we have to set up an optimization scheme . we define the cost function ( all lengths in , all energies in ev ) @xmath108 where @xmath109 is the negative force field due to the @xmath7-bond in the hckel hubbard - ohno description . using this cost function for the parameter optimization , the hckel hubbard - ohno model will provide a suitable description of the @xmath7-bonds in ethene and ethyne . as a first step , we seek the optimal value for the bare hckel model , i.e. , we optimize @xmath110 . the result is @xmath111 . the hckel model with @xmath112 provides a good description of the @xmath7-bonds , see fig . [ fig : forcefields ] . the bare hckel force field , @xmath113 deviates from the force fields @xmath114 by only a few tenth of an ev / . as a consequence , the hckel model reproduces the bond lengths @xmath115 and @xmath116 and the parameters @xmath117 and @xmath118 from quantum chemistry calculations with good accuracy , see table [ tab : hhofit ] . the success of the bare hckel model indicates that the hubbard - ohno interaction can not improve the results very much . more importantly , for moderate values for @xmath85 ( @xmath119 ) and for @xmath20 of the order of one angstrm , the dependence of @xmath120 on @xmath20 is fairly small , and the range of acceptable values for @xmath84 and @xmath85 is quite large for the optimization functions chosen . correspondingly , short - range parameterizations of the ppp potential can give parameter values very different from ours . @xcite given the finite accuracy of the quantum chemistry data , it is therefore difficult to derive reliable values for @xmath84 and @xmath85 from our fits . @ccccc@ & @c@ @xmath115 + + & @c@ @xmath117 + + ev / @xmath121 & @c@ @xmath122 + + & @c@ @xmath118 + + ev / @xmath121 + + experiment & 1.3390 & & 1.203 & + quantum chemistry & 1.3372 & 58.60 & 1.2097 & 101.07 + hckel model ( @xmath123 ) & 1.3403 & 57.28 & 1.2079 & 100.10 + hckel hubbard - ohno model & 1.3417 & 55.66 & 1.2071 & 99.28 we note , however , that @xmath84 and @xmath85 strongly influence the size of the single - particle gap and the exciton binding energy in polymers . therefore , we argue that the coulomb parameters for short molecules should not differ much from the parameter set @xmath124 as obtained from our analysis of the pda spectra . @xcite for this reason , we restrict ourselves to the optimization of @xmath125 , and obtain @xmath126 as the optimal value . as for the bare hckel model , the hckel hubbard - ohno model reproduces the bond lengths and force parameters from quantum chemistry calculations with good accuracy , see table [ tab : hhofit ] . the overall agreement with the force functions is also quite good for all carbon - carbon distances @xmath99 , see fig . [ fig : forcefields ] . the analysis of the bond energies in our di - carbon molecules permits two conclusions . first , the peierls coupling should be @xmath127 which is somewhat smaller than the value proposed by su , schrieffer and heeger , @xmath128 . @xcite similar values , with a deviation of @xmath129 , were generally used for the description of @xmath7-conjugated polymers . @xcite second , we can expand the @xmath5-bond potential around the average bond distance in trans - pa to determine the spring constant @xmath13 . we taylor expand the @xmath5-bond force field @xmath130 around @xmath131 , @xmath132 and find ( @xmath133 is in units of @xmath134 ) @xmath135 and @xmath136 , see table [ tab : kvalues](b ) . the first term , @xmath137 , describes the repulsive force of the @xmath5-bond . it opposes the shrinking of the @xmath5-bonds in trans - pa from @xmath138 down to @xmath19 . this repulsive force must be compensated by the binding due to the itinerant @xmath7-electrons . the second term describes the enhanced spring constant due to the compressed @xmath5-bond , @xmath139 , so that we should set @xmath140 . this value can be compared with the literature values used for trans - polyacetylene . @xcite our analysis of the @xmath5-bond potential in ethane , @xmath6 , supports the larger value derived in ref . [ ] , @xmath17 . moreover , we find @xmath141 which implies that the electron - phonon coupling constant , @xmath142 is small , @xmath143 . @xcite therefore , polaronic effects are predicted to be of minor importance for trans - polyacetylene , in contrast to the ssh picture , @xmath144 . @xcite the values for the electron - phonon coupling and the @xmath5-bond potential @xmath6 are important for the theoretical description of the bond lengths in pa . we find that the simple hckel model can not account for the dimerization in trans - polyacetylene . we consider @xmath145 unit cells with two carbon atoms each . the spin-1/2 electrons move on sites @xmath146 , and periodic boundary conditions apply . the system is half filled , i.e. , the number of electrons equals the number of sites , @xmath147 ; the system is paramagnetic , @xmath148 . in the hckel description , the electrons move between neighboring sites , @xmath149 \ ; , \nonumber \\\end{aligned}\ ] ] where @xmath150 are the electron transfer matrix elements for the single - bonds and double - bonds , respectively . in this ansatz we take into account the bond dimerization ( peierls effect ) . the lengths of the single and double bonds are given by @xmath151 here , @xmath152 describes the average bond - length reduction from @xmath153 to @xmath154 , and @xmath155 describes the bond - length alternation . the total hamiltonian is given by the sum of the electrons kinetic energy and the potential energy contribution from @xmath6 , @xmath156 at the optimal values of @xmath152 and @xmath155 , the ground - state energy of @xmath157 has its minimum . experimentally , @xcite we have @xmath158 and @xmath159 with @xmath160 , so that @xmath161 and @xmath162 . to determine the ground - state energy as a function of @xmath152 and @xmath155 , we introduce the dimensionless units @xmath163 the bare dispersion relation @xmath164 and the hybridization function @xmath165 are given by @xmath166 here , we use the abbreviation @xmath167 $ ] . the hckel - peierls hamiltonian is diagonal in reciprocal space , @xcite @xmath168 ^ 2+[\delta(k)]^2 } \nonumber \\ & = & 2\tilde{t}_0 e^{\sigma}\sqrt{[\cosh(\delta)]^2-[\sin(k)]^2 } \ ; . \label{tdiapeierls}\end{aligned}\ ] ] here , @xmath169 is the dispersion relation for the upper ( @xmath170 ) and lower ( @xmath1 ) peierls band . the ground state is the peierls insulator , @xmath171 where the lower peierls band is completely filled . note that the wave numbers @xmath172 are quantized in units of @xmath173 because the chain has @xmath174 sites . the sum of the electrons kinetic energy and of the lattice potential energy per unit cell is given by @xmath175 ^ 2-[\sin(k)]^2 } \ ; . \nonumber \\\end{aligned}\ ] ] a factor of two in the kinetic energy accounts for the spin degeneracy . the minimization with respect to @xmath5 gives @xmath176 ^ 2-[\sin(k)]^2 } \nonumber \\ & = & \frac{t_0}{\alpha } \bigl [ f_{\sigma}(r_{\sigma}-(t_0/\alpha)\sigma_0+(t_0/\alpha)\delta_0)\nonumber \\ & & \phantom{\bigl[}+ f_{\sigma}(r_{\sigma}-(t_0/\alpha)\sigma_0-(t_0/\alpha)\delta_0 ) \bigr ] \ ; .\label{eq : firstmin}\end{aligned}\ ] ] the minimization with respect to @xmath177 leads to @xmath178 ^ 2-[\sin(k)]^2 } } \nonumber \\ & = & \frac{t_0 } { \alpha } \bigl [ f_{\sigma}(r_{\sigma}-(t_0/\alpha)\sigma_0+(t_0/\alpha)\delta_0 ) \nonumber \\ & & \hphantom{\frac{t_0 } { \alpha}\bigl[}- f_{\sigma}(r_{\sigma}-(t_0/\alpha)\sigma_0-(t_0/\alpha)\delta_0 ) \bigr ] \ ; . \label{eq : secondmin}\end{aligned}\ ] ] the equations ( [ eq : firstmin ] ) and ( [ eq : secondmin ] ) must be solved simultaneously to obtain the values for the ground - state distortions @xmath179 and @xmath180 . this is done using mathematica . @xcite when we use @xmath111 and @xmath6 from eq . ( [ eq : defvsigmaetc ] ) with the parameters from table [ tab : kvalues ] , we find that the @xmath5-bond shrinks by @xmath181 so that the average bond length is @xmath182 , in good agreement with experiment . however , the dimerization is @xmath183 , an order of magnitude smaller than in experiment . these numbers do not change significantly when we use the linear approximation @xmath184 $ ] for @xmath185 . this shows that the curvature of the force field can be ignored when we optimize the structure in the vicinity of the equilibrium distance , @xmath186 . for given @xmath187 and @xmath188 , the hckel - peierls model requires the parameters @xmath189 and @xmath190 , corresponding to the much smaller spring constant @xmath14 suggested for trans - polyacetylene . @xcite the comparison shows that additional terms must be included in the hamiltonian , e.g. , the coulomb interaction between the @xmath7-electrons , that must be responsible for a large part of the bond dimerization in trans - polyacetylene . experimentally , it is very difficult to determine the single - particle gap in trans - polyacetylene because high - quality single - crystals as for pda can not be fabricated . therefore , franz - keldysh oscillations of unbound single - particle excitations have not been detected in electro - absorption experiments on trans - polyacetylene . the optical absorption of polyacetylene films becomes significant above @xmath191 and shows a peak at @xmath192 ; the electro - absorption measurements display a strong signal at @xmath193 . @xcite third - harmonic generation is large at @xmath194 which is evidence for an excitonic state at @xmath195 , @xcite as also seen in combined absorption / refraction measurements , @xmath196 . @xcite apparently , the linear absorption spectrum of trans - polyacetylene results from disorder - broadening of the exciton resonance . @xcite we assume that the exciton binding energy in trans - polyacetylene is of the same order of magnitude as in other conjugated polymers such as pda , @xmath197 . @xcite then , the single - particle gap is estimated to be @xmath198 . these estimates are supported by calculations of mott - wannier excitons for correlated electrons in one dimension . @xcite we compare these numbers with the predictions from the hckel - peierls model . the peierls insulator has the single - particle gap @xmath199\sinh(\delta_0)\nonumber \\ & \approx & 4\alpha\delta_0 \ ; . \label{eq : gaphueckel}\end{aligned}\ ] ] the approximation holds because we have @xmath200 and @xmath201 . from eq . ( [ eq : gaphueckel ] ) we see that the combination of @xmath202 with the experimental value @xmath203 leads to a hckel - peierls gap of @xmath204 . apparently , the peierls gap alone can not account for the observed single - particle gap in trans - polyacetylene . the hckel hubbard - ohno hamiltonian includes the coulomb interaction of the @xmath7-electrons in the hubbard - ohno approximation , @xmath205 with the hckel part @xmath157 from eq . ( [ eq : hueckelhamilt ] ) and @xmath206 with @xmath207 from eq . ( [ eq : ohnoexpression ] ) . the carbon atoms are at the positions @xmath208 of a zig - zag chain in the @xmath209-@xmath210-plane as is shown in fig . [ fig : structure ] . we optimize such trans - polyacetylene geometry numerically as will be discussed briefly below . in the ideally dimerized zig - zag lewis structure with alternating double and single bonds between the carbon atoms ( black dots ) . linked to each carbon atoms are the hydrogen atoms ( white circles ) on alternating sides of the chain.[fig : structure],title="fig:",height=124 ] + we employ the density - matrix renormalization group ( dmrg ) method @xcite together with the dynamic block state selection ( dbss ) approach , @xcite to calculate the ground - state energy and excited - state energies for the hckel hubbard - ohno model for up to @xmath211 carbon atoms ( @xmath212 ) for fixed bond parameters . we use a fixed - point recursion method to optimize the geometry . @xcite in this procedure , dmrg is called iteratively , thus playing the role of a kernel function . the electronic hamiltonian for a fixed geometry is solved by the dmrg , and expectation values of the required operators are determined from the obtained wavefunction . these quantities are used to minimize the total energy comprising the electronic contribution and the lattice potential energy . this geometrical optimization terminates when the energy difference between two subsequent iteration steps gets below an a - priori defined threshold that we set to @xmath213 . a more detailed description will be given in a subsequent paper . @xcite in addition , we employ the force field @xmath214 \ ; , \ ] ] and start our analysis with the parameter set motivated in sect . [ sec : hhomodel ] , @xmath215 and @xmath216 . moreover , we show data for an improved parameter set , @xmath217 and @xmath218 . for a comparison with our earlier study on polydiacetylene , we fix @xmath219 and @xmath220 . furthermore , the dielectric screening of the surrounding medium is incorporated using the dielectric constant @xmath221 for the long - range part of the coulomb interaction . moreover , we use @xmath222 , @xmath223 . the results for the average bond length @xmath224 are shown in fig . [ fig : dmrg - bonds ] . as for the non - interacting case , the hckel hubbard - ohno model almost perfectly describes the bond - length reduction from @xmath153 to @xmath225 . we find @xmath226 for our first parameter set ( @xmath215 , @xmath216 ) as motivated in sect . [ sec : hhomodel ] , and @xmath227 for the improved , second parameter set ( @xmath217 , @xmath218 ) , in very good agreement with experiment , @xmath228 . now that @xmath229 for @xmath230 , we see that the electron - electron interaction and the parameter @xmath231 do not significantly influence the average bond length . moreover , the analysis of the bond potential @xmath6 provides a good estimate of @xmath232 . in angstrm as a function of the inverse system size @xmath233 in the hckel hubbard - ohno model with @xmath230 , @xmath222 , and a linear @xmath5-bond force field @xmath130 with @xmath215 , @xmath216 ( red circles ) , @xmath217 , @xmath234 ( blue squares ) , and @xmath217 , @xmath218 ( black crosses ) . the experimental value @xmath203 is shown as a horizontal line , the quadratic extrapolation lines are included as a guide to the eye . [ fig : dmrg - dimer],width=283 ] + in angstrm as a function of the inverse system size @xmath233 in the hckel hubbard - ohno model with @xmath230 , @xmath222 , and a linear @xmath5-bond force field @xmath130 with @xmath215 , @xmath216 ( red circles ) , @xmath217 , @xmath234 ( blue squares ) , and @xmath217 , @xmath218 ( black crosses ) . the experimental value @xmath203 is shown as a horizontal line , the quadratic extrapolation lines are included as a guide to the eye . [ fig : dmrg - dimer],title="fig:",width=283 ] in contrast , the dimerization sensitively depends on the parameter for the @xmath5-bond spring constant @xmath231 , see fig . [ fig : dmrg - dimer ] . moreover , the estimate for @xmath216 as motivated in sect . [ sec : hhomodel ] leads to a too small dimerization even in the presence of the electron - electron interaction . indeed , we find @xmath235 for the parameter set ( @xmath215 , @xmath216 ) , as compared to @xmath236 from the bare hckel model and @xmath203 from experiment . apparently , the electron - electron interaction substantially increases the dimerization . for the first parameter set , the dimerization in presence of the hubbard - ohno interaction is by a factor five larger than the peierls contribution alone . + in ev as a function of the inverse system size @xmath233 in the hckel hubbard - ohno model with @xmath230 , @xmath222 , and a linear @xmath5-bond force field @xmath130 with @xmath215 , @xmath216 ( red circles ) , @xmath217 , @xmath234 ( blue squares ) , and @xmath217 , @xmath218 ( black crosses ) . the quadratic extrapolation lines are included as a guide to the eye . [ fig : dmrg - exc],title="fig:",width=302 ] to obtain a better agreement with the experimentally observed dimerization , we address the improved parameter set ( @xmath217 , @xmath218 ) . we find @xmath237 , as compared to @xmath238 and @xmath203 . the value for the dimerization now agrees with the experimental value within experimental error bars . the electron - electron interaction still is decisive for the dimerization in trans - polyacetylene because the electronic contribution to the dimerization is a factor 1.4 larger than the peierls contribution . the hckel hubbard ohno results for the exciton energy and the single - particle gap are shown in figs . [ fig : dmrg - exc ] and [ fig : dmrg - gaps ] , respectively . the exciton energies extrapolate to @xmath239 and @xmath240 , within the experimental bounds @xmath241 . the value from the improved parameter set is in good agreement with the prediction from third - harmonic generation . @xcite the position of the exciton energy sensitively depends on the force - field parameter @xmath231 . the corresponding results for the single - particle gap are @xmath242 and @xmath243 . the binding energy of the exciton @xmath244 is predicted to be @xmath245 , and @xmath246 , in agreement with experiment . @xcite apparently , the binding energy @xmath247 increases slowly with decreasing force - field parameter @xmath231 . + in ev as a function of the inverse system size @xmath233 in the hckel hubbard - ohno model with @xmath230 , @xmath222 , and a linear @xmath5-bond force field @xmath130 with @xmath215 , @xmath216 ( red circles ) , @xmath217 , @xmath234 ( blue squares ) , and @xmath217 , @xmath218 ( black crosses ) . the quadratic extrapolation lines are included as a guide to the eye . [ fig : dmrg - gaps],title="fig:",width=302 ] in this work we investigated the @xmath5-bonds and @xmath7-bonds in ethane ( h@xmath0c@xmath1ch@xmath0 ) , ethene ( a.k.a . ethylene , h@xmath2c@xmath3ch@xmath2 ) , and ethyne ( a.k.a . acetylene , hc@xmath4ch ) as a function of the carbon - carbon distance @xmath20 . we demonstrated that the @xmath7-bonds in ethene and ethyne can be described using the hckel model with the potential @xmath6 from the @xmath5-bond . the bond lengths and spring constants in equilibrium agree with the data from quantum chemistry within a margin of a few percent . the comparison provides a robust estimate for the value of the peierls coupling , @xmath248 , for a given electron transfer @xmath222 at carbon - carbon distance @xmath19 . unfortunately , the parameters of the hubbard - ohno interaction can not be determined from dimers or short polyenes because the ohno interaction is essentially constant for small distances . therefore , we choose @xmath219 and @xmath220 as derived from the the analysis of excited states in polydiacetylene . @xcite we tested the hckel hubbard - ohno model for trans - polyacetylene with @xmath6 as backbone potential . close to the average bond length @xmath225 , we may linearize the @xmath5-bond force @xmath249 $ ] when we determine the structure . the @xmath5-bond repulsion balances the lattice contraction induced by the itinerant @xmath7-electrons . we find that the size of the average bond contraction is mostly determined by the constant term @xmath232 and the peierls coupling @xmath83 whereas the coulomb interaction and the linear term @xmath231 are fairly unimportant for the average bond length . moreover , the optimal value for @xmath232 is very well predicted by @xmath6 , @xmath250 while our analysis for trans - polyacetylene suggests @xmath251 . the dimerization @xmath188 in trans - polyacetylene is triggered to a large part by the coulomb interaction . naturally , the dimerization strength sensitively depends on the size of the ` spring constant ' @xmath231 . we find that the value obtained from the analysis of the @xmath5-bond potential , @xmath252 , is too large . for an agreement with experimental data in trans - polyacetylene , we propose to use the smaller value @xmath253 , in agreement with empirical values for benzene , @xmath18 , that has the same average bond length . @xcite our value is considerably larger than @xmath14 proposed for trans - polyacetylene in ref . [ ] and closer to the value suggested in ref . [ ] , @xmath17 . given these parameter sets , we calculated the energy for elementary excitations in trans - polyacetylene . we find an exciton with substantial binding energy , @xmath254 , in agreement with experiments for @xmath7-conjugated materials . @xcite the parameter @xmath231 mildly affects the exciton binding energy but determines the energetic position of the exciton . for our second , optimal parameter set [ @xmath222 , @xmath230 , @xmath219 , @xmath220 , @xmath251 , @xmath255 , we find a good agreement with experiment , @xmath256.@xcite the single - particle gap is found at @xmath257 . our values for @xmath258 and @xmath259 also agree with the predictions from recent calculations of mott - wannier excitons for correlated electrons in one dimension . @xcite in sum , the analysis of short molecules gives a reasonable first estimate for the parameters necessary for a hckel hubbard - ohno description of conjugated polymers . to reproduce the experimental ground - state conformation , some parameters , typically the ` spring constant ' at the optimal average bond length , must be adjusted by some 20% . after the adjustment of these parameters , the hckel hubbard - ohno model provides a fairly good description for @xmath7-electrons in trans - polyacetylene , as can be seen from the good agreement of theoretical and experimental data for the exciton energy and the exciton binding energy . the measured optical phonon spectra provide another testing case for the hckel hubbard - ohno model . indeed , this theoretical approach reproduces the optical phonons in trans - polyacetylene with good accuracy , as we shall show in a subsequent paper . @xcite we thank g. frenking , m. hermann , and p. knowles for useful discussions and for providing us their quantum - chemistry data for comparison . this research was supported in part by the hungarian research fund ( otka ) under grant nos . k 100908 and nn 110360 . l.v . was supported by the grant agency of the czech republic ( grant no 15 - 10279y and grant no . 16 - 12052s ) . s. kivelson , w .- p . su , j. r. schrieffer , and a. j. heeger , phys . * 58 * , 1899 ( 1987 ) ; d. baeriswyl , p. horsch , and k. maki , phys . * 60 * , 70 ( 1987 ) ; j. t. gammel and d. k. campbell , phys . lett . * 60 * , 71 ( 1987 ) ; s. kivelson , w .- p . su , j. r. schrieffer , and a. j. heeger , phys . 60 * , 72 ( 1987 ) . t. kubo , t. watanabe , t. nishioka , h. takezoe , and a. fukuda , jpn . j. appl . * 31 * , 3372 ( 1992 ) . m. liess , s. jeglinski , z. v. vardeny , m. ozaki , k. yoshino , y. ding and t. barton , phys . b * 56 * , 15712 ( 1997 ) .

quantum chemistry calculations provide the potential energy between two carbon atoms in ethane ( h@xmath0c@xmath1ch@xmath0 ) , ethene ( h@xmath2c@xmath3ch@xmath2 ) , and ethyne ( hc@xmath4ch ) as a function of the atomic distance . based on the energy function for the @xmath5-bond in ethane , @xmath6 , we use the hckel model with hubbard ohno interaction for the @xmath7 electrons to describe the energies @xmath8 and @xmath9 for the @xmath10 double bond in ethene and the @xmath11 triple bond in ethyne , respectively . the fit of the force functions shows that the peierls coupling can be estimated with some precision whereas the hubbard - ohno parameters are insignificant at the distances under consideration . we apply the hckel - hubbard - ohno model to describe the bond lengths and the energies of elementary electronic excitations of trans - polyacetylene , ( ch)@xmath12 , and adjust the @xmath5-bond potential for conjugated polymers .

SECTION 1. SHORT TITLE. This Act may be cited as the ``Orphan Products Extension Now Accelerating Cures and Treatments Act of 2017''. SEC. 2. EXTENSION OF EXCLUSIVITY PERIODS FOR A DRUG APPROVED FOR A NEW INDICATION FOR A RARE DISEASE OR CONDITION. (a) In General.--The Federal Food, Drug, and Cosmetic Act is amended by inserting after section 505F of such Act (21 U.S.C. 355g) the following: ``SEC. 505G. EXTENSION OF EXCLUSIVITY PERIODS FOR A DRUG APPROVED FOR A NEW INDICATION FOR A RARE DISEASE OR CONDITION. ``(a) Designation.-- ``(1) In general.--The Secretary shall designate a drug as a drug approved for a new indication to prevent, diagnose, or treat a rare disease or condition for purposes of granting the extensions under subsection (b) if-- ``(A) prior to approval of an application or supplemental application for the new indication, the drug was approved or licensed under section 505(c) of this Act or section 351(a) of the Public Health Service Act but was not so approved or licensed for the new indication; ``(B)(i) the sponsor of the approved or licensed drug files an application or a supplemental application for approval of the new indication for use of the drug to prevent, diagnose, or treat the rare disease or condition; and ``(ii) the Secretary approves the application or supplemental application; and ``(C) the application or supplemental application for the new indication contains the consent of the applicant to public notice under paragraph (3) with respect to the designation of the drug. ``(2) Revocation of designation.-- ``(A) In general.--Except as provided in subparagraph (B), a designation under paragraph (1) shall not be revoked for any reason. ``(B) Exception.--The Secretary may revoke a designation of a drug under paragraph (1) if the Secretary finds that the application or supplemental application resulting in such designation contained an untrue statement of material fact. ``(3) Notice to public.--The Secretary shall provide public notice of the designation of a drug under paragraph (1). ``(b) Extension.-- ``(1) In general.--If the Secretary designates a drug as a drug approved for a new indication for a rare disease or condition, as described in subsection (a)(1)-- ``(A)(i) the 4-, 5-, and 7\1/2\-year periods described in subsections (c)(3)(E)(ii) and (j)(5)(F)(ii) of section 505, the 3-year periods described in clauses (iii) and (iv) of subsection (c)(3)(E) and clauses (iii) and (iv) of subsection (j)(5)(F) of section 505, and the 7-year period described in section 527, as applicable, shall be extended by 6 months; or ``(ii) the 4- and 12-year periods described in subparagraphs (A) and (B) of section 351(k)(7) of the Public Health Service Act and the 7-year period described in section 527, as applicable, shall be extended by 6 months; and ``(B)(i) if the drug is the subject of a listed patent for which a certification has been submitted under subsection (b)(2)(A)(ii) or (j)(2)(A)(vii)(II) of section 505 or a listed patent for which a certification has been submitted under subsection (b)(2)(A)(iii) or (j)(2)(A)(vii)(III) of section 505, the period during which an application may not be approved under section 505(c)(3) or section 505(j)(5)(B) shall be extended by a period of 6 months after the date the patent expires (including any patent extensions); or ``(ii) if the drug is the subject of a listed patent for which a certification has been submitted under subsection (b)(2)(A)(iv) or (j)(2)(A)(vii)(IV) of section 505, and in the patent infringement litigation resulting from the certification the court determines that the patent is valid and would be infringed, the period during which an application may not be approved under section 505(c)(3) or section 505(j)(5)(B) shall be extended by a period of 6 months after the date the patent expires (including any patent extensions). ``(2) Relation to pediatric and qualified infectious disease product exclusivity.--Any extension under paragraph (1) of a period shall be in addition to any extension of the periods under sections 505A and 505E of this Act and section 351(m) of the Public Health Service Act, as applicable, with respect to the drug. ``(c) Limitations.--Any extension described in subsection (b)(1) shall not apply if the drug designated under subsection (a)(1) has previously received an extension by operation of subsection (b)(1). ``(d) Definition.--In this section, the term `rare disease or condition' has the meaning given to such term in section 526(a)(2).''. (b) Application.--Section 505G of the Federal Food, Drug, and Cosmetic Act, as added by subsection (a), applies only with respect to a drug for which an application or supplemental application described in subsection (a)(1)(B)(i) of such section 505G is first approved under section 505(c) of such Act (21 U.S.C. 355(c)) or section 351(a) of the Public Health Service Act (42 U.S.C. 262(a)) on or after the date of the enactment of this Act. (c) Conforming Amendments.-- (1) Relation to pediatric exclusivity for drugs.--Section 505A of the Federal Food, Drug, and Cosmetic Act (21 U.S.C. 355a) is amended-- (A) in subsection (b), by adding at the end the following: ``(3) Relation to exclusivity for a drug approved for a new indication for a rare disease or condition.--Notwithstanding the references in paragraph (1) to the lengths of the exclusivity periods after application of pediatric exclusivity, the 6-month extensions described in paragraph (1) shall be in addition to any extensions under section 505G.''; and (B) in subsection (c), by adding at the end the following: ``(3) Relation to exclusivity for a drug approved for a new indication for a rare disease or condition.--Notwithstanding the references in paragraph (1) to the lengths of the exclusivity periods after application of pediatric exclusivity, the 6-month extensions described in paragraph (1) shall be in addition to any extensions under section 505G.''. (2) Relation to exclusivity for new qualified infectious disease products that are drugs.--Subsection (b) of section 505E of the Federal Food, Drug, and Cosmetic Act (21 U.S.C. 355f) is amended-- (A) by amending the subsection heading to read as follows: ``Relation to Pediatric Exclusivity and Exclusivity for a Drug Approved for a New Indication for a Rare Disease or Condition.--''; and (B) by striking ``any extension of the period under section 505A'' and inserting ``any extension of the periods under sections 505A and 505G, as applicable,''. (3) Relation to pediatric exclusivity for biological products.--Section 351(m) of the Public Health Service Act (42 U.S.C. 262(m)) is amended by adding at the end the following: ``(5) Relation to exclusivity for a biological product approved for a new indication for a rare disease or condition.--Notwithstanding the references in paragraphs (2)(A), (2)(B), (3)(A), and (3)(B) to the lengths of the exclusivity periods after application of pediatric exclusivity, the 6-month extensions described in such paragraphs shall be in addition to any extensions under section 505G.''. SEC. 3. ORPHAN DRUGS. (a) In General.--Section 527 of the Federal Food, Drug, and Cosmetic Act (21 U.S.C. 360cc) is amended-- (1) in subsection (a), in the matter following paragraph (2), by striking ``such drug for such disease or condition'' and inserting ``the same drug for the same disease or condition''; (2) in subsection (b)-- (A) in the matter preceding paragraph (1), by striking ``If an application'' and all that follows through ``such license if'' and inserting ``During the 7-year period described in subsection (a) for an approved application under section 505 or license under section 351 of the Public Health Service Act, the Secretary may approve an application or issue a license for a drug that is otherwise the same, as determined by the Secretary, as the already approved drug for the same rare disease or condition if''; (B) in paragraph (1), by striking ``notice'' and all that follows through ``assure'' and inserting ``of exclusive approval or licensure notice and opportunity for the submission of views, that during such period the holder of the exclusive approval or licensure cannot ensure''; and (C) in paragraph (2), by striking ``such holder provides'' and inserting ``the holder provides''; and (3) by adding at the end the following: ``(c) Condition of Clinical Superiority.-- ``(1) In general.--If a sponsor of a drug that is designated under section 526 and is otherwise the same, as determined by the Secretary, as an already approved or licensed drug is seeking exclusive approval or exclusive licensure described in subsection (a) for the same rare disease or condition as the already approved drug, the Secretary shall require such sponsor, as a condition of such exclusive approval or licensure, to demonstrate that such drug is clinically superior to any already approved or licensed drug that is the same drug. ``(2) Definition.--For purposes of paragraph (1), the term `clinically superior' with respect to a drug means that the drug provides a significant therapeutic advantage over and above an already approved or licensed drug in terms of greater efficacy, greater safety, or by providing a major contribution to patient care. ``(d) Regulations.--The Secretary may promulgate regulations for the implementation of subsection (c). Beginning on the date of enactment of the Orphan Products Extension Now Accelerating Cures and Treatments Act of 2017, until such time as the Secretary promulgates regulations in accordance with this subsection, the Secretary may apply any definitions set forth in regulations that were promulgated prior to such date of enactment, to the extent such definitions are not inconsistent with the terms of this section, as amended by such Act. ``(e) Demonstration of Clinical Superiority Standard.--To assist sponsors in demonstrating clinical superiority as described in subsection (c), the Secretary-- ``(1) upon the designation of any drug under section 526, shall notify the sponsor of such drug in writing of the basis for the designation, including, as applicable, any plausible hypothesis offered by the sponsor and relied upon by the Secretary that the drug is clinically superior to a previously approved drug; and ``(2) upon granting exclusive approval or licensure under subsection (a) on the basis of a demonstration of clinical superiority as described in subsection (c), shall publish a summary of the clinical superiority findings.''. (b) Rule of Construction.--Nothing in the amendments made by subsection (a) shall affect any determination under sections 526 and 527 of the Federal Food, Drug, and Cosmetic Act (21 U.S.C. 360bb, 360cc) made prior to the date of enactment of the Orphan Products Extension Now Accelerating Cures and Treatments Act of 2017. SEC. 4. PEDIATRIC INFORMATION ADDED TO LABELING. Section 505A(o) of the Federal Food, Drug, and Cosmetic Act (21 U.S.C. 355a(o)) is amended-- (1) in the subsection heading, by striking ``Under Section 505(j)''; (2) in paragraph (1)-- (A) by striking ``under section 505(j)'' and inserting ``under subsection (b)(2) or (j) of section 505''; and (B) by striking ``or by exclusivity under clause (iii) or (iv) of section 505(j)(5)(F)'' and inserting ``, or by exclusivity under clause (iii) or (iv) of section 505(j)(5)(F), clauses (iii) and (iv) of section 505(c)(3)(E), or section 527(a), or by an extension of such exclusivity under this section or section 505E''; (3) in paragraph (2), in the matter preceding subparagraph (A)-- (A) by inserting ``clauses (iii) and (iv) of section 505(c)(3)(E), or section 527,'' after ``section 505(j)(5)(F),''; and (B) by striking ``drug approved under section 505(j)'' and inserting ``drug approved pursuant to an application submitted under subsection (b)(2) or (j) of section 505''; and (4) by amending paragraph (3) to read as follows: ``(3) Preservation of pediatric exclusivity and other provisions.--This subsection does not affect-- ``(A) the availability or scope of exclusivity under-- ``(i) this section; ``(ii) section 505 for pediatric formulations; or ``(iii) section 527; ``(B) the question of the eligibility for approval of any application under subsection (b)(2) or (j) of section 505 that omits any other conditions of approval entitled to exclusivity under-- ``(i) clause (iii) or (iv) of section 505(j)(5)(F); ``(ii) clause (iii) or (iv) of section 505(c)(3)(E); or ``(iii) section 527; or ``(C) except as expressly provided in paragraphs (1) and (2), the operation of section 505 or section 527.''.

Orphan Products Extension Now Accelerating Cures and Treatments Act of 2017 This bill amends the Federal Food, Drug, and Cosmetic Act to require the Food and Drug Administration (FDA) to extend by six months the exclusivity period for an approved drug or biological product when the product is additionally approved to prevent, diagnose, or treat a new indication that is a rare disease or condition (also known as an orphan disease). The FDA may revoke an extension if the application for the new indication contained an untrue material statement. The FDA must notify the public of products that receive this extension and patents related to those products. Products may receive only one of these extensions. This extension is in addition to other extensions. Only products approved after enactment of this bill for a new indication that is a rare disease or condition are eligible for an extension. For a medication to be approved as an orphan drug with seven years of marketing exclusivity when it is the same medication for the same condition as an already approved orphan drug, the sponsor of the new medication must demonstrate that the new medication is clinically superior to the approved medication. The bill expands to cover brand name drugs provisions that allow generic drugs to be approved and marketed without labeling for pediatric indications when the pediatric indications are protected by patent or marketing exclusivity.

free - tissue transfer has become the standard treatment for autologous breast reconstruction . in breast reconstruction , postoperative complications and the final aesthetic outcomes anatomical and clinical studies have increased the physiological knowledge of flaps used in breast reconstruction . however , although overall free flap success rates are above 95% , thrombosis of the arterial or venous anastomosis is still a dramatic complication , which may lead to flap loss . in contrast to the increased knowledge on flap design , little is known about the anaesthetic and perioperative management , which may have an effect on the outcome of microvascular surgery . in 1985 , macdonald proposed that it is important to maintain adequate arterial pressure and cardiac output . it is generally accepted that good perfusion pressure is essential to flap survival [ 1 , 2 ] . anaesthesiologists attempt to restore vascular volume based not only on clinical signs such as heart rate , arterial blood pressure and urine output but also on calculations of maintenance , third - space losses and blood loss . it is common practice to use generous amounts of fluid resuscitation since it is believed that modest hypervolaemia reduces the sympathetic tone and therefore dilates the supplying vessels to the flap . in addition , a mild increase in central venous pressure will increase the cardiac output . on the other hand , the excessive use of fluid therapy may therefore increase the complication rate in reconstructive surgery . the reason for this retrospective study was to analyse perioperative fluid therapy , its effect on hemodynamic parameters and its effect on the outcome of the free - tissue transfer . all surgical interventions were performed by experienced plastic surgeons . during the period of this study , the muscle sparing free transverse rectus abdominis myocutaneous ( tram ) flap technique was used for the reconstruction . in this surgical procedure , a small medial part of the rectus abdominis is harvested along with several lateral and medial perforating vessels of the deep inferior epigastric artery . after complete dissection , the flap is divided into four perfusion zones as previously reported . all four zones were included in the flap , and the end - to - end anastomosis was performed using the internal mammary artery . all patients eligible for breast reconstruction with the muscle sparing free tram flap were included in the study regardless of relative risk factors such as smoking , obesity , chest wall irradiations and chemotherapy . flap characteristics , e.g. flap weight , reconstructed breast weight , ischemia time and incidence of postoperative complications , were noted . outpatient recording charts were used to detect any late complications such as wound dehiscence , minor partial flap loss or fat necrosis . using the anaesthesia operative / recovery charts , type ( crystalloid or colloid ) and volume of fluid therapy and hemodynamics parameters these parameters were recorded at a 15-min interval during surgery followed by hourly recording up to discharge from the recovery area 24 h after surgery . after completion of the anastomosis , all patients received intravenous dextran ( 30 cm / h ) ; this is commonly used by microsurgeons to decrease vascular thrombosis . in the 108 consecutive patients , the free tram flap was used for secondary unilateral breast reconstruction . the anaesthesia / recovery chart these four cases were excluded from further analysis . for the remaining 104 patients , the perioperative data was thoroughly recorded and found suitable for inclusion in the study . mean age at time of operation was 48.4 0.8 ( range , 2768 ) years . body mass index ( bmi ) was 26.3 0.5 ( range , 17.532.4 ) kg . fifty percent of patients received radiotherapy , and 67% of the patients received chemotherapy preoperatively . mean flap ischemia time was 57.6 3.6 ( range , 32120 ) min . history of smoking was repentantly recorded in only 50% of the patients . of these patients , 40.7% were non - smokers , 24.1% were active smokers at the time of surgery and 35.2% stopped smoking prior to surgery . in table 1 seventeen patients ( 16% ) had minor flap complications ( mi - fc ) , which were managed conservatively , and patients recovered with either no or just minor negative effects on the aesthetic results . two cases returned because of postoperative bleeding ; these two patients recovered with no further complications . in one patient , failure of the anastomosis was discovered too late , and this patient had total flap loss ( tfl ) . in 11 patients ( 11% ) , the anastomosis was revised , and the salvage percentage after revision of the anastomosis was 55% . of the 11 anastomosis revisions , two patients had arterial occlusion , which was detected early in the postoperative period by means of absent doppler signal . in the remaining nine patients , this was usually detected at a later stage due to a positive doppler signal form the intact arterial anastomosis . as consequence , these patients had a high rate of tfl and major flap complication ( ma - fc ) . in addition , all four patients with successful venous anastomosis revision developed ma - fc , requiring a second return to operating theatre for debridement . table 1definitions and abbreviations of complicationsabbreviationdefinitionseveritycosmeticsmi - fcminor flap complications : fat necrosis ( without skin loss ) or small flap necrosis < 5%)minornone to minor effect on cosmetic resultma - fcmajor flap complication : partial flap necrosis ( > 5%)major ; requiring reoperation : debridement in theatremajor effect on cosmetic resulttfltotal flap losssevereflap failure to reconstruct , usually worse cosmetic appearancerarevision of anastomosismajor ; requiring reoperation : redo of the anastomosis or repositioningno effect on cosmetic result if procedure is successful and no other complication occur definitions and abbreviations of complications in addition , 13 patients experienced ma - fc , which eventually resulted in a poor cosmetic appearance . this resulted in a total of 17 patients with ma - fc ( 15% ; table 2 ) . table 2complicationsreturn to operating theatreconservative treatmentpostoperative bleedinganastomosis revisiondebridementmi - fcnonenonenone15ma - fc1413 + 4nonetflnone51 + 5nonetotal2112315four secondary debridement after revision of anastomosisfive secondary debridement after revision of anastomosistwo patients received musculocutaneous latissimus dorsi flap in conjunction with implants for reconstruction , three patients needed split skin graft for closure and in the remaining 18 patients , the defect could be closed after removable of non - viable tissue four secondary debridement after revision of anastomosis five secondary debridement after revision of anastomosis two patients received musculocutaneous latissimus dorsi flap in conjunction with implants for reconstruction , three patients needed split skin graft for closure and in the remaining 18 patients , the defect could be closed after removable of non - viable tissue there was an overall good cosmetic result in 79% of patients and an inferior cosmetic result in 15% of patients . six percent of patients experienced tfl . in two of these patients , a musculocutaneous latissimus dorsi flap in conjunction of a breast implant was used for reconstruction at a later stage . risk factors such as obesity ( defined as bmi > 28 ) , radiotherapy and chemotherapy were not associated with complications . smoking was not found to be a significant risk factor for the development of pfl in this study . no significant differences were found in the hemodynamics ( blood pressure and heart rate ) and in temperature during the first 24 h after surgery when comparing patients with or without complications ( fig . 1 ) . the mean volume of fluid therapy preoperatively was 4.20 0.14 l. haematocrit level prior to surgery was 0.39 0.03% and dropped to 0.32 0.04% at the end of the procedure . mean arterial pressure ( map ) during anastomosis was 72.1 1.4 mmhg . the volume of fluid therapy ( colloid + crystalloid ) did not affect hemodynamics during the perioperative period ( fig . 2 , the use of colloid fluid therapy did not affect the total volume of fluid therapy nor did it have any effect on the outcome . 1mean arterial pressure ( map ) is compared in patients with or without complicationsfig . 2the effect of fluid therapy on mean arterial pressure is shown . as a cut - off point , 4.2 l was used which was the mean volume of fluid therapy that was administered mean arterial pressure ( map ) is compared in patients with or without complications the effect of fluid therapy on mean arterial pressure is shown . as a cut - off point , 4.2 l was used which was the mean volume of fluid therapy that was administered in addition , fluid therapy did not affect overall complications ( fig . 3 ) . however , in patients who returned to surgery due to thrombus formation of the anastomosis , the volume of fluid therapy was significantly higher ( fig . 4 ) . fig . 3perioperative fluid therapy in patients with uneventful procedure is compared with patients who experienced one or more complications ( e.g. postoperative bleeding , major flap complication , minor flap complication , total flap loss and anastomosis revision)fig . 4perioperative fluid therapy in patients with adequate anastomosis is compared to patients with anastomosis failure requiring anastomosis revision perioperative fluid therapy in patients with uneventful procedure is compared with patients who experienced one or more complications ( e.g. postoperative bleeding , major flap complication , minor flap complication , total flap loss and anastomosis revision ) perioperative fluid therapy in patients with adequate anastomosis is compared to patients with anastomosis failure requiring anastomosis revision maintenance of adequate perfusion pressure was predominantly maintained by administration of fluid therapy . however , in 14 patients , a bolus of ephedrine was used during surgery in order to maintain adequate blood pressure , which had not responded adequately on fluid therapy alone . map , which caused the attending anaesthesiologist to administer ephedrine , and subsequent increase in map are shown in table 3 . the use of ephedrine was associated with a lower total volume of fluid therapy ( fig . table 3patient characteristics with ephedrine administrationcase no.complicationephedrine , mg / ivbp at tatabp increaseincrease mapbp aafluid ( l)bpmapbpmapbpmap1none1090/4560b115/607818115/65824.442none3070/5560b105/657818110/60774.103none2075/4052d100/607321100/60774.604ma - fc1080/4557b105/65782195/60726.795tfl7.580/4557b100/5060370/50574.136none580/4053b120/75903795/50687.467none595/3555b120/75583110/60775.658mi - fc595/5065b120/60801595/45625.989ma - fc4065/4048b95/55682085/55654.7110none10.590/3553b95/4058595/35555.6811none1585/5062a105/65781690/55674.7512mi - fc1590/5567b110/658013125/75925.5313none3565/4552b95/45621090/40573.3014none12.580/4557b100/60731695/60724.91bp and map are shown in millimetres of mercurybp blood pressure , ta time of administration ( ephedrine ) , map mean arterial pressure , b before anastomosis , d during anastomosis , a after anastomosisfig . 5perioperative fluid therapy is compared in patients with or without ephedrine patient characteristics with ephedrine administration bp and map are shown in millimetres of mercury bp blood pressure , ta time of administration ( ephedrine ) , map mean arterial pressure , b before anastomosis , d during anastomosis , a after anastomosis perioperative fluid therapy is compared in patients with or without ephedrine breast reconstructive surgery and flap failure pose a great burden on the self - image and the quality of life of patients recovering from breast cancer . increased anatomical and physiological flap knowledge has improved the outcome after autologous breast reconstructive surgery . however , there are still some uncertainties on perioperative management and the effect it may have on the final outcome . the results in this retrospective study suggest that aggressive fluid management may trigger anastomosis failure , which , in a majority of patients , leads to further complications such as tfl and increased incidence of ma - fc . anaesthetic management in free flap surgery has been described in the literature [ 1 , 2 , 7 , 8 ] . a series of principles such as maintenance of a high cardiac output , systolic pressure > 100 mmhg , low systemic vascular resistance , normothermia , high urine output and effective analgesia , together with a mild haemodilution to a haematocrit value of 3035% , results in compromise . these are usually obtained by the use of a deliberate fluid management [ 1 , 7 - 10 ] . these studies also advocate not using vasoactive agents due to either the increase in systemic vascular resistance or decrease in cardiac output . however , these basic principles are more based on animal studies rather than on evidence - based medicine . anaesthesiologists view the entire body as having flow that is dependent on systemic perfusion pressure , whereas reconstructive surgeons convene that systemic administration of vasoactive agents cause vasoconstriction of the pedicle artery and the microvasculature . clinically , vasoactive agents may lead to increased difficulty during dissecting due to vasoconstriction of perforating vessels . however , massey et al . demonstrated the safe and effective use of epinephrine in an experimental model . in addition , a clinical study comparing dopamine with dobutamine demonstrated that if vasoactive agents are needed during microvascular surgery , dobutamine seems to be more beneficial than dopamine in terms of cardiac output and flap perfusion . in this study , only a minor bolus of ephedrine was used in 14 patients with no adverse effects on the complication rates . ephedrine did lead to a reduced fluid volume therapy in this group ; however , this was not significant ( fig.3 ) . perioperative fluid therapy is the subject of much controversy in general surgery . in respect to reconstructive free flap surgery , the flaps used in reconstructive surgery are prone to ischemia and hypoxia , which implies a considerable risk of wound healing and flap complications . deliberate fluid therapy causes haemodilution , which may further deteriorate oxygenation because of the lack of erythrocytes . on the other hand , it could improve oxygenation because of increased microcirculatory blood flow . in experimental studies , normovolaemic haemodilution reduces risk of thrombosis and increases flap oxygenation . in clinical studies , the debate of deliberate fluid therapy versus restrictive fluid therapy is still ongoing [ 15 , 16 ] , although a recent review favours restrictive fluid therapy . in this study , a high volume of fluid therapy during surgery was retrospectively associated with a significant higher incidence of return to the operating theatre for revision of the anastomosis . the majority of these patients developed further complications such tfl or ma - fc leading to return to the operating theatre for debridement . a possible pathogenic explanation is that fluid overload precipitates oedema in the flap and therefore impairs the microcirculation . in addition , the free flaps may be especially susceptible to oedema formation due to the loss of lymphatic drainage . based on the results of this study , a goal - directed or more restricted intravenous fluid therapy in addition with safe use of inotropes may be recommended . fluid loss should be replaced , but fluid overload should be avoided in breast reconstruction with free - tissue transfer .

to increase perfusion pressure with vasoactive drugs may be in conflict with the opinion of the reconstructive surgeon who maintains that the systemic administration of vasoactive agents causes vasoconstriction of the pedicle artery and the microvasculature . in free flap surgery , deliberate fluid therapy is used with a minimum of vasoactive drugs . this retrospective study was performed to analyse the perioperative fluid therapy , its effect on hemodynamic parameters and on the outcome of free flap surgery . one hundred and four patients were included in this retrospective study . the muscle sparing free transverse rectus abdominis myocutaneous flap was used for breast reconstruction . perioperative hemodynamic data was used for this study . twenty - seven patients had one or two complications requiring return to the operating room ( or ) . two cases returned to the or because of postoperative bleeding ; in 11 patients , the anastomosis was revised . the reason for surgery in the latter group was venous stasis , due to thrombus formation at the venous anastomosis . the volume of fluid therapy was significantly higher in patients who returned to the or due to thrombus formation at the anastomosis . based on the results of this study , restricted intravenous fluid therapy or guided fluid therapy is recommended . invasive monitoring such as central venous pressure and invasive arterial monitoring is recommended . fluid loss should be replaced , and fluid overload should be avoided when the breast is reconstructed using free - tissue transfers .

NIAMEY (Reuters) - French and Nigerien troops were conducting operations on Thursday in a region of Niger where three U.S. Army Special Forces members were killed the day before, becoming the first American soldiers to die in West Africa in decades. Three Nigerien soldiers were also killed and two U.S. soldiers wounded in the attack, which took place in a southwestern Niger region where insurgents are active, U.S. Africa Command spokeswoman Robyn Mack said. France’s regional Barkhane force was asked to support a counterattack after the Niger and U.S. troops were ambushed, French army spokesman Colonel Patrick Steiger told a news conference in Paris. “It’s not clear if the attackers knew the Americans were present,” said a Western security source. “Initial information suggests there was a trap that appeared designed to get them out of their vehicles and then they opened fire.” Insurgents in the area include militants from al Qaeda in Islamic Maghreb and a local branch of Islamic State, Mack said. The Western security source said al Qaeda and a relatively new group called Islamic State in the Greater Sahara were the main suspects, although no one had yet claimed responsibility. Two other Niger security sources said four military helicopters had been sent to the region and that reinforcements arrived on Thursday morning in the Tillaberi area, where the attack took place. The Pentagon declined to discuss details, citing ongoing operations, but said the U.S. forces were part of a growing mission to bolster Niger’s armed forces’ ability to battle militants. “We extend our deepest condolences and sympathies to the families of the fallen, and those injured in this attack,” Pentagon spokeswoman Dana White told a news briefing. AMBUSH Nigerien army Colonel Abou Tagué said the joint Nigerian-American patrol on the Mali-Niger border was ambushed by militants riding “in a dozen vehicles and about 20 motorcycles near the village of Tongo Tongo.” He cited intense fighting, saying the joint Nigerian-American force “showed courage.” He said four Nigerien soldiers were killed and eight were wounded. A statement by U.S. Africa Command on Thursday said one unspecified “partner nation member” had died but did not name the nation. In a speech on Thursday, Niger President Mahamadou Issoufou condemned the attack. “Our country has just been the victim of a terrorist attack that claimed a large number of victims,” he said. Islamist militants form part of a regional insurgency in the poor, sparsely populated deserts of West Africa’s Sahel. Jihadists have stepped up attacks on U.N. peacekeepers, Malian soldiers and civilian targets since being driven back in northern Mali by a French-led military intervention in 2013. Malian militant groups have expanded their reach into neighboring countries, including Niger, where a series of attacks by armed groups led the government in March to declare a state of emergency in the southwest. The European Union has pledged tens of millions of euros to a new regional force of five Sahelian countries - Niger, Mali, Chad, Burkina Faso and Mauritania - in a bid to contain Islamist militant groups. The United States also views the region as a growing priority. Rinaldo Depagne, West Africa project director at International Crisis Group, said the borderlands between Mali, Niger and Burkina Faso were “becoming a new permanent hotbed of violence”, threatened by increasingly organized militant groups. “This shows the level of organization of these groups and also their confidence,” Depagne said. Andrew Lebovich, a visiting fellow at the European Council on Foreign Relations, said Wednesday’s attack revealed how U.S. training of Nigerien forces “has accelerated and also verged into ongoing military operations”. The United States has about 800 service members in Niger, where it operates surveillance drones out of a $100 million base in the central city of Agadez to support the country’s efforts to combat jihadists and protect its porous borders. It has also sent troops to supply intelligence and other assistance to a multinational force battling the Nigerian Boko Haram militants near Niger’s border with Nigeria. ||||| (CNN) Three US Green Berets were killed and two others were wounded in southwest Niger near the Mali-Niger border when a joint US-Nigerien patrol was attacked Wednesday, US officials told CNN. A US official told CNN that initial indications are the Green Berets were ambushed by up to 50 fighters who are thought to be affiliated with ISIS. US Africa Command, which oversees military operations in Africa, issued a statement Thursday saying the two wounded US service members were "evacuated in stable condition to Landstuhl Regional Medical Center in Germany." Officials told CNN that French military Super Puma helicopters evacuated the wounded Americans along with those killed in action while also providing covering fire. The attack occurred approximately 200 kilometers north of the country's capital, Niamey, in southwest Niger, according to the statement from Africa Command. JUST WATCHED Niger: Strange mix of US military and migrant hub Replay More Videos ... MUST WATCH Niger: Strange mix of US military and migrant hub 05:58 Five Nigerien soldiers also were killed in the attack, according to a Nigerien security official. The officials cautioned that this was still an early assessment. The Green Berets were part of a team advising and assisting local forces when they were attacked. A US defense official told CNN that operations are underway in the area to locate the attackers. A spokeswoman for the French Ministry of Defense confirmed that French troops from the Barkhane anti-terror force based in Chad are currently involved in an operation in Niger. She said the operation is being led by Niger and the French troops are there to support them. She added that no French soldiers were killed during Wednesday night's ambush. US Africa Command confirmed in a statement Thursday morning that three US service members were killed in the attack and said the names were being withheld pending the notification of next of kin. "US forces are in Niger to provide training and security assistance to the Nigerien Armed Forces, in their efforts to counter violent extremist organizations in the region," the statement said. President Donald Trump was briefed on the attack by chief of staff John Kelly, White House press secretary Sarah Sanders said Wednesday night. A U.S. Army Special Forces weapons sergeant observes a Niger Army soldier during marksmanship training in Diffa, Niger, in February 2017. Supporting role for US military in Niger There are about 800 US troops in Niger, and the US military has maintained a presence in the northwest African country for five years, with small groups of US Special Operations Forces advising local troops as they battle two terrorist groups, ISIS-affiliated Boko Haram and al Qaeda's North African branch, al Qaeda in the Islamic Maghreb. "Niger is an important partner of ours, we have a deep relationship with them," Lt. Gen. Kenneth McKenzie, the director of the Joint Staff, told reporters at the Pentagon Thursday. "We are committed to that relationship, we believe that they are as well. In fact, I think it's a very good success story," he added. US officials view Chad, Niger and Mali as being particularity important as they serve as bridges between north and sub-Saharan Africa, saying that local al Qaeda and ISIS affiliates use their control of these transit routes to gain revenue that helps them recruit, expand and export attacks. ISIS uses these North-South transit routes to move fighters northward, where they can gain more easily access Europe and the West. One official told CNN that ISIS is attempting to illegally infiltrate the gold mining industry in Niger to sell on the black market and finance world terrorism. Al Qaeda in the Islamic Maghreb has maintained a presence in the Mali-Niger border area, despite a multi-year French-led military counterterrorism effort, Operation Barkhane, which began in 2014. The US military has largely played a supporting role, providing intelligence, surveillance and reconnaissance assets in support of French forces operating in Mali and Niger. The French operation involves thousands of French troops as well as forces from Germany, Mali, Niger and other countries in the region. And while US troops largely play a supporting role, military leaders acknowledge the risks they face. "Clearly there's risks for our forces in Niger," McKenzie said while declining to discuss the specifics of Wednesday's attack, citing "ongoing partnered operations." "Any time we deploy full forces globally we look very hard at the enablers that need to be in place in order to provide security for them and that ranges from the ability to pull them out if they're injured to the ability to reinforce them at the point of a fight if they need reinforcement," he added. "US forces are in Niger to provide training and security assistance to the Nigerien Armed Forces, including support for intelligence, surveillance and reconnaissance efforts, in their efforts to target violent extremist organizations in the region," said US Navy Lt. Cmdr. Anthony Falvo, a spokesman for US Africa Command, adding, "one aspect of that is training, advising and assisting the Nigeriens in order to increase their ability to bring stability and security to their people." Terror groups in Libya Wednesday's attack comes after US drones struck ISIS fighters in neighboring Libya twice in a week in late September. Those two missions, the first under the Trump administration, suggest US officials have become increasingly concerned that the terror group is regaining strength in Libya. More than two dozen ISIS fighters were killed in the airstrikes, US Africa Command said. While the ISIS presence in Libya has been much reduced following a near five-month-long US air campaign against the terror group in the final stretch of the Obama administration, small groups of ISIS fighters had begun to reconstitute themselves in remote desert areas, taking advantage of the lingering instability resulting from the Libyan civil war. US airmen frtake down tents from the old base to move to a new location, on September 11, 2017, at Air Base 201 in Agadez, Niger. "ISIS and al Qaeda have taken advantage of ungoverned spaces in Libya to establish sanctuaries for plotting, inspiring and directing terror attacks; recruiting and facilitating the movement of foreign terrorist fighters; and raising and moving funds to support their operations," US Africa Command said in a September 28 statement. US Africa Command did not specify where the US drones used in the Libya strikes were launched from, but the Pentagon is in the process of establishing a drone base just outside the city of Agadez in Niger in an effort to bolster regional counterterrorism efforts. The US has been using a local Nigerien airport while the base is under construction, according to US Africa Command. A US Africa Command news release dated October 2 says the construction of the Agadez airbase "is projected to be the biggest military labor troop project in US Air Force history." "While nearby terrorist cells and human smuggling are an ongoing threat, the remote location makes daily operations a task unto themselves," says the story posted on the US Africa Command's website. Wednesday's casualties were not the first this year in the US fight against terror groups in Africa. In May, a US Navy SEAL was killed in Somalia during an operation against local al Qaeda affiliate al Shabaab. The SEAL was the first US service member killed in action in Somalia since 1993, when two Black Hawk helicopters were shot down and 18 American soldiers were killed in the Battle for Mogadishu.

– The deaths of three Green Berets in Niger on Wednesday—along with those of several Nigerien soldiers—is raising questions about the US mission in the African country, reports the Washington Post. The incident, involving what are believed to be the first hostile-fire casualties in the country for US troops, took place 120 miles north of the capital of Niamey near Niger's border with Mali. An official tells CNN that US forces were ambushed by as many as 50 ISIS fighters, though earlier reports suggested they met with al-Qaeda militants. Reuters reports they may have fallen victim to a "trap." So why are they there? A rep for US Africa Command says "US forces are in Niger to provide training and security assistance to the Nigerien Armed Forces, including support for intelligence, surveillance and reconnaissance efforts," in the battle against extremists. According to the Post, 800 US personnel are in Niger, with most involved in the gathering of reconnaissance from Niamey. The US is also working on a base for surveillance drones in Agadez, closer to northern Mali and southern Libya. Lt. Gen. Kenneth McKenzie, director of the Pentagon's Joint Staff, stressed that the overall mission in Niger wasn't considered combat. He added that the relationship between Niger and US forces is "a very good success story." But Andrew Lebovich of the European Council on Foreign Relations tells the Atlantic the incident "seems to sow some potential confusion: It was reportedly a training exercise very close to where jihadist groups are very active." He concludes that "the US seems to be getting closer and closer to combat operations," per the Post.

noncarious cervical lesions ( nccls ) are becoming an increasingly important factor when considering the long - term health of the dentition . in fact , the occurrence of this condition is steadily increasing [ 14 ] . according to the present literature available , it is not possible to determine a unique etiological factor , but there is a concern that it is a multifactorial condition [ 58 ] . these lesions can affect tooth sensitivity , plaque retention , caries incidence , structural integrity , and pulp vitality , and they present unique challenges for successful restoration [ 59 ] . these challenges involve each step of the restoration process , including isolation , adhesion , insertion technique , and finishing and polishing . a successful diagnosis and treatment plan requires keen observation , a thorough patient history , and careful evaluation . this work aims to provide some knowledge of the nccls ' characteristics and etiologic covariables as well as improve assessment of prognosis by aiding in proper case selection for treatment and in the selection of appropriate treatment protocols . this could be reached with a complete patient anamnesis accompanied by a careful clinical examination . some studies suggest that treatment provided for nccls may not be based on the correct diagnosis [ 3 , 4 ] . it is important to diagnose the tooth wear process in children and adults as early as possible . diagnosing early forms of erosion is difficult , as erosion is accompanied by few signs and fewer , if any , symptoms . therefore , clinical appearance is the most important feature for dental professionals when diagnosing this condition . commonly , when the nccl is painless and does not affect esthetics , there is no complaint by the patient . sometimes , it is not completely painless , but the dentin is partially ( or completely ) covered by dental plaque , tartar , or gum . a simple removal ( or displacement ) of this coverage followed by the application of some stimulus ( like a delicate air blast ) can initiate a pain process . when pain is present , the location of the lesion becomes easier to detect . pain is one of the factors that will directly influence the decision for restorative therapy as well as the technique employed . as soon as the dental caries is eliminated as primary cause , the possible factors involved have to be identified . these noncarious processes may include abrasion , corrosion , and ( possibly ) abfraction , acting alone or in combination . there are factors associated directly with the genesis of nccl , such as occlusion , saliva , age , sex , diet , and parafunctional habits [ 11 , 12 ] . if teeth are worn on their occlusal surfaces , incisal surfaces , or both by friction from the food bolus , this wear is termed masticatory abrasion . masticatory abrasion can also occur on the facial and lingual aspects of teeth , as coarse food is forced against these surfaces by the tongue , lips , and cheeks during mastication . we should not underestimate the relevance of some current diet habits , which are considered but potentially destructive to the teeth ( granolas , nuts , all bran cereal , and acid juices ) . abrasion can also occur as a result of overzealous tooth brushing , improper use of dental floss and toothpicks , or detrimental oral habits . frequently , they appear as painless cavities with polished surfaces , but pain is not an uncommon occurrence . typically , when improper tooth brushing is one of the causes of the nccls , the enamel resists differently than the dentin which erodes following the path made by the toothbrush [ 39 ] . in dentistry , the term erosion is used to define the loss of dental hard tissues by chemical action not involving bacteria . erosion , as defined by the american society for testing and materials committee on standards , is the progressive loss of a material from a solid surface due to mechanical interaction between that surface and a fluid , a multi component fluid , impinging liquid or solid particles . corrosion is the more appropriate term and represents tooth surface loss caused by chemical or electrochemical action . there are both endogenous and exogenous sources of corrosion . in cases of endogenous sources of corrosion , such as bulimia or gastro esophageal reflux disease ( gerd ) , the enamel appears thin and translucent , enamel is lost on the posterior occlusal and anterior palatal surfaces , and depressions occur at the cervical areas of upper anterior teeth . cupped , or invaginated , areas develop where dentin has been exposed on the occlusal surfaces of posterior teeth because of wear . in the exogenous sources of corrosion , the aspect is similar , but the tissue loss location modifies following the areas related to the passage of the corrosive element . it has been reported that any food substance with a critical ph value of less than 5.5 can become a corrodent and demineralize teeth . this may occur as a result of consuming highly acidic foods and beverages such as citrus fruits , carbonated soft drinks , and sucking on sour candies . acidulated carbonated soft drinks have become a major component of many diets , particularly among adolescents and young children . it is evident that this condition does not exclusively affect the cervical areas , but , in association with other factors , it will act synergistically . abfraction is thought to take place when excessive cyclic , nonaxial tooth loading leads to cusp flexure and stress concentration in the vulnerable cervical region of teeth . such stress is then believed to directly or indirectly contribute to the loss of cervical tooth substance [ 5 , 7 , 8 , 1623 ] . although there is theoretical evidence in support of abfraction , predominantly from finite element analysis studies , caution is advised when interpreting results of these studies due to their limitations [ 9 , 2426 ] . frequently , more than two mechanisms may be involved in the etiology of tooth surface lesions , featuring a multifactorial phenomenon . when to these two mechanisms are added the effect of stress ( abfraction ) resulting from bruxism or occlusal interference , these lesions then become corrosive - abrasive abfractive in nature . the interplay of chemical , biological , and behavioral factors is crucial and helps to explain why some individuals exhibit more erosion than others [ 5 , 7 ] . therefore , awareness of a multifactorial etiology in noncarious cervical lesions may help the clinician to formulate an appropriate treatment plan for the patient . abrasion is the most cited etiological factor for development of nccl . in clinical surveys , 94% of respondent dentists classified the lesion as abrasion , and 66% rated tooth brushing as the most likely cause . cervical toothbrush abrasions are generally thought to be a consequence of toothbrush factors such as frequent or forceful tooth brushing , faulty or vigorous techniques , filament stiffness or design , dominant hand dexterity , or abrasive dentifrices . however , investigations can not conclusively establish one factor as the primary etiology because of conflicting results . therefore , an array of aspects related to toothbrush factors may operate in conjunction with dental erosion and occlusal loading . the clarification of patients , their orientation about brushing techniques , and the change of some of the above factors can bring tangible results and must be performed . another etiology that can be effectively modified is the chemical corrosion ( also called dental erosion ) and should be correctly diagnosed . when derived from eating disorders ( bulimia ) or and gerd , the treatment may require the participation of a physician . the extrinsic etiology is more easily treatable ; removing or altering the harmful habit , as in the abrasion etiology , provides consistent results . when the abfraction etiology is diagnosed , no consensus on treatment strategies exists . it is important that oral health professionals understand that abfraction is still a theoretical concept , as it is not proved . as a result of the reported associations between occlusal interferences and abfraction lesions , and between loading direction ( influenced by cusp inclines ) and unfavorable tensile stresses , occlusal adjustment has been advocated to prevent their initiation and progression and to minimize failure of cervical restorations . occlusal adjustments may involve altering cusp inclines , reducing heavy contacts , and removing premature contacts . in fact , inappropriate occlusal adjustments may increase the risk of certain conditions such as caries , occlusal tooth wear , and dentine hypersensitivity . the science of occlusion is complex , and the treatment requires understanding , care , and experience . although it is desirable to reduce lateral forces on teeth with stress - induced cervical lesions , extensive restorative procedures , such as the reestablishment of anterior guidance or orthodontic movement , require cost - and - benefit justification . occlusal adjustment should be undertaken only in cases where the interferences are well established and diagnosed . the professional must be enabled to do the adjustments and be aware that this procedure must be performed only when strictly indicated . the adjustment must be carried out in order to remove only the interferences , preserving the original points of centric occlusion . it is a conservative procedure , since it involves only the application of a composite resin , but it is important to carefully observe the possibility of excessive stress concentrated on this tooth . in fact , it is recommended that destructive , irreversible treatments aimed at treating so - called abfraction lesions , such as occlusal adjustment , must be avoided or implemented only in exceptional cases . occlusal splints , aimed at reducing the amount of nocturnal bruxism and nonaxial tooth forces , have been recommended to prevent the initiation and progression of abfraction lesions . however , it should be noted that the use of occlusal splints to reduce bruxism is still a controversial topic . although they provide a conservative treatment option for managing suspected abfraction lesions , according to some authors , there is no evidence base to support their use [ 9 , 24 ] . in the presence of evidence of the relevance of the abfraction mechanism in the development of lesions , the occlusal splint should be considered as a good treatment strategy due to its conservative nature . it should be noted that when restoring nccls , clinicians are not treating the etiology but are merely replacing what has been lost . others recommend early intervention [ 6 , 16 , 24 , 26 , 27 ] . there are no generally accepted , specific guidelines in the literature stating that all lesions should be restored . logic and good clinical judgment would suggest that they should be restored when clinical consequences ( e.g. , dentine hypersensitivity ) have developed or are likely to develop in the near future . cervical restorations may contribute to increased plaque accumulation potentially leading to caries and periodontal disease [ 11 , 24 , 25 ] . there are different reasons for the need for restorative treatment : the structural integrity of the tooth is threatened , the exposed dentin is hypersensitive , the defect is esthetically unacceptable to the patient , or pulp exposure is likely to occur . when the dentist is against nonsensitive shallow cavities that do not provide additional plaque retention the possible causes of the nccls should be identified and eliminated ( or treated ) . if the abfraction etiology is considered , the occlusion should be marked with red and blue articulating paper to check whether there has been any change , and photographic records from an occlusal view should be taken . if a progression of the nccls is diagnosed , changes in the therapy should be considered , providing restorative treatment if necessary [ 6 , 19 ] . once the restorative treatment is indicated , the dentist has to know the different causes and aspects of each situation and choose the best strategy to employ . unfortunately , although nccl restorations are a very common occurrence in clinics , they also represent one of the less durable types of restorations and have a high index of loss of retention , marginal excess , and secondary caries . despite these restorations being a continuing problem in restorative dentistry , failure of cervical adhesive restorations is often attributed to inadequate moisture control , adhesion to different opposite substrates ( enamel and dentin ) , differences in dentin composition , and also cusp movement during occlusion . in order to help adopt the best restorative strategy , problems with restoring nccls include difficulty in obtaining moisture control and gaining access to subgingival margins [ 10 , 2830 ] . rubber dam clamps , gingival retraction cord , and periodontal surgery are methods that can be used to retract and control the gingival tissues , and thus facilitate access and also control moisture . the exudation of gingival fluid is possibly one of the challenges to adhesion in cervical region , which is already impaired by other factors ( such as the absence of enamel in the gingival wall of the cavity and the characteristics of the dentin in nccls ) . intrinsic anatomical and morphological characteristics of the cervical region create limitations in the placement of the rubber dam and clamp . proper isolation , is very difficult , sometimes impossible , when lesions extend proximally or under the gingiva . sometimes part of the structure can not be isolated and the dam promotes restorative material accumulation . when adequate rubber dam isolation is not possible another isolation method has to be employed . another option is a proposed association of mylar matrix with wood wedges and a photocured gingival barrier . in any case , a proper isolation is the first step for the success in restoring nccls but , despite being the basis for the other subsequent steps , is probably the most underestimated one . even with advanced destruction , minimally invasive restorative intervention , such as sealing or covering with composite material it is evident from the recent literature that there is no place for metallic materials such as amalgam and gold in the modern day restoration of nccls . glass ionomer cements ( gics ) , resin - modified gics ( rmgics ) , a gic / rmgic liner base laminated with a resin composite , and resin composite in combination with a dentine bonding agent are all restorative options [ 24 , 3135 ] . some authors recommend that rmgic should be the first preference for restoration of nccls or , in aesthetically demanding cases , a gic / rmgic liner base with resin composite [ 32 , 33 ] . indeed gic presents several characteristics that make them a good choice : biocompatibility , adhesion to calcified substrates ( especially in cases of dentin sclerosis where traditional adhesion may underperform ) , and elastic modulus similar to the dentin . however , some other characteristics make its use infrequent : technical difficulties related to the material 's stickiness , poor esthetics , solubility particularly in acidic oral environments , and retention failure occurrences . some authors claim that under the action of parafunctional loadings , fracture - induced failure of cervical gic restorations occurs at the cervical margin . it is further shown that prior to fracture , the restorative material undergoes strain softening , which in turn introduces damage and weakens the materials involved . the softening of the material occurs in the cervical region of the restoration area which has been linked to the location of most of the clinical observed failures . the author does not indicate gic or rmgic frequently , but it is a good indication in deep nccls , where a laminate technique ( sandwich technique with composite resins ) can be used . the best materials for restoration of nccls are the composite resins . within this group of materials , some authors recommend that nccls suspected of being caused primarily by abfraction should be restored with a microfilled resin composite or a flowable resin that has a low modulus of elasticity , as it will thus flex with the tooth and not compromise retention [ 34 , 3638 ] . however , no definitive conclusion can be found in the literature addressing the difference between failures rates of resin composites of different stiffness used to restore nccls . nevertheless , in must situation , the authors recommend low modulus composites or associations of composites with different modulus . after the isolation another important , and commonly neglected , step should be performed : the prophylaxis of the cavity . due to their nature , nccls are lined with a contaminated layer that resists adhesion . the gingival proximity ( sometimes partially or totally covering the cavity ) makes this procedure a more complex step . in some cases , rotary prophylactic brushes can not be used in order to avoid mechanical aggression and bleeding . in nonsensitive cavities , the authors recommend rubbing the cavity and its periphery with a cotton pellet soaked with an anionic detergent , followed by rinsing with water , drying , and conventional total acid etching ( 37% phosphoric acid10 seconds on dentins and 20 seconds on enamel ) with the aim of removing the sticky layer . even when the roughening procedure is performed , the same sequence is recommended . in the presence of sensitivity , rubbing with detergent is still indicated but the phosphoric acid should be applied only on enamel . when a conventional gic is chosen , the previous conditioning with polyacrylic acid is indicated in order to provide a good surface wetting . if an rmgic is chosen , pretreatment of dentin with self - etch adhesive systems , before filling , seems to be a good alternative to the conventional dentin conditioner provided by the manufacturer . some recent studies demonstrate important histological differences between prepared dentin and the affected dentin from nccls . one work based on raman analysis showed that the distinct compositional and structural alterations in mineral and matrix components of nccls affected dentin . a heterogeneous hypermineralized layer , with characteristic features such as high phosphate / low carbonate content , high degree of crystallinity , and partially denatured collagen , was revealed in the affected dentin substrate of nccls [ 39 , 40 ] . in another study focusing on adhesion to sclerotic dentin , the authors observed that most dentinal tubules were obliterated by rod - like sclerotic casts and could not be dissolved by acid etching . both the hybrid zone and the resin tags were observed in sclerotic dentin after restoration . although resin tags were fewer , and in lack of communications , the length of resin tags and the thickness of the hybrid zone were almost similar to those of the sound dentin . they concluded that bonding to sclerotic dentin is different from bonding to sound dentin and may be compromised by fewer resin tags and communications . transmission electron microscopy revealed that in addition to occlusion of the tubules by mineral crystals , many parts of wedge - shaped cervical lesions contain a hyper mineralized surface that resists the etching action of both self - etching primers and phosphoric acid . examination of both sides of the failed bonds revealed a wide variation in fracture patterns that involved all of these structures . microtensile bond strengths to the occlusal , gingival , and deepest portions of these wedge - shaped lesions were significantly lower than similar areas artificially prepared in normal teeth . further studies are required to understand the role that these alterations play in response to acid etching and bonding to these clinically relevant substrates . further , some authors agree that restorations placed in teeth whose dentin / enamel had been prepared , or roughened , showed a statistically significant higher retention rate than those placed in teeth with unprepared dentin [ 10 , 43 ] . considering these studies and the author 's clinical experience , a mild roughening of the superficial dentin with a diamond point is indicated when restoring polished nonsensitive nccls . this procedure does not create additional sensitivity and aims to get a more reliable adhesion in this specific situation . if the cavity is deep and provides sufficient thickness , a sandwich technique may be performed , taking advantage of the gic 's good adhesion to calcium . it is important to note that adhesives with direct interaction with calcium have been recently developed and present a promising option in these cases . , it is logical to conclude , based on hydrodynamic theory , that the dentin tubules are not obliterated ; on the contrary , they are probably opened . thus , the etching should be gentle in order to provide a good substrate to adhesion without enhancing sensitivity . based on this , and considering the available adhesives , the self - conditioning ( se ) adhesives should be the first choice . although several articles doubt their efficiency in aspects such as bond strength and marginal discoloration , others demonstrate acceptable clinical performance [ 4549 ] . a previous acid etching of the surrounding enamel is indicated because , as known , the microretentions created by the se adhesives are not enough to give adhesive strength similar to that achieved by conventional acid etching . within this group , the self - etching primers ( two steps ) present better results than the self - etching adhesives ( one step ) [ 5052 ] . one must always remember that an active application of these adhesives should be employed , rubbing the surface with a soaked microbrush for 15-seconds , waiting other 15 second period to allow volatilization of solvents . this is important because the cervical wall of the cavity tends to retain excess of adhesive which leads to future discoloration and gap formation . despite the apparent easy access and insertion , nccl presents some particularities that should be emphasized . this may justify the high documented failure rate [ 30 , 33 , 5355 ] and the number of published articles about this theme [ 10 , 34 , 36 , 5667 ] . the first point that creates difficulties is that the cavity limits are not well defined , especially the proximal limits location . . every effort should be made to delimit the future restoration , because the excess removal and the finishing and polishing present other difficulties . the simple fact of working with cavities on opposite walls from dissimilar tissues like dentin and enamel already creates intrinsic problems . several restorative techniques have been proposed to minimize shrinkage due to polymerization and also to achieve better marginal adaptation in class v cavities . because bond strength to enamel is usually greater than to dentin , it was suggested that cavities could be restored in multiple layers , starting with incremental placement in the occlusal wall of the preparation . it has also been suggested that the contraction gap at the gingival margin caused by polymerization shrinkage could be prevented by the incremental placement of a composite material starting in the dentin portion of the preparation . regarding the possibility of bulk placement , it has been stated that this often results in open dentin margins , thus increasing microleakage . since enamel adhesion is stronger , more stable , and more predictable , the insertion of material should begin from the gingival wall , without surrounding enamel . avoiding concomitant insertion on opposite walls and leaving a free surface , the adhesion to the cervical wall can be achieved without antagonistic forces . whenever possible , the cavity should be restored with three , or at least two , increments . employing a careful technique is possible to achieve a restoration with minimum or no finishing and polishing procedures needed . considering esthetics , the color of the cervical area is easy to obtain , usually with a higher saturation and smaller translucency compared to the color of the other two thirds of the tooth . any excess or roughness plaque retention , gingival inflammation , and occurrence of caries lesions represent not only a failure of the restoration but also a creation of new problems to the patient . poorly performed finishing and polishing procedures can lead to damage to the soft and hard tissues . techniques with minimum need of finishing and polishing are ideal , but properly contoured restorations are seldom achieved without the need to remove excess material [ 10 , 6872 ] . when they are needed , a good option is the use of delicate diamond finishing points followed by application of a surface sealant or a liquid polisher [ 10 , 72 , 73 ] . as emphasized before , treatment of nccls is not easy , and sometimes , new procedures or different approaches are needed . semiannual appointments should be performed in order to observe the evolution of the lesions , the conditions of the restorations , and other concerns of the patient . also , the maintenance of the surface polish can be performed with a new surface sealant application . treating nccls necessarily involves these steps : problem identification , diagnosis , etiological factor removal , or treatment , and , if necessary , restoration . due to the multifactorial character , it is not a simple procedure . a successful diagnosis and treatment plan requires a thorough patient history and careful observations and evaluations .

at this time , restoration of noncarious cervical lesions ( nccls ) is a common occurrence in clinics nowadays . some reasons for this are the growth of the elderly population , a smaller rate of tooth loss , and possibly the increase of some etiologic factors . these factors include inadequate brushing techniques in gingival recession cases , corrosive food and drink consumption , and occlusal stress concentrating factors ( occlusal interferences , premature contacts , habits of bruxism , and clenching ) . unfortunately , class v restorations also represent one of the less durable types of restorations and have a high index of loss of retention , marginal excess , and secondary caries . some causes for these problems include difficulties in isolation , insertion , contouring , and finishing and polishing procedures . this work aims to help dentists in choosing the best treatment strategy , which necessarily involves steps of problem identification , diagnosis , etiological factor removal or treatment , and , if necessary , restoration . finally , appropriate restorative techniques are suggested for each situation .

SANAA/ADEN U.S. special forces stormed a walled compound in a remote Yemeni village early on Saturday in an attempt to free Western hostages held by an al Qaeda unit, but an American journalist and a South African teacher were killed by their captors, officials said. U.S. Secretary of State John Kerry and a Yemeni intelligence official said Luke Somers, 33, and South African Pierre Korkie, 56, were shot by their kidnappers shortly after the raid began in the arid Wadi Abadan district of Shabwa, a province long seen as one of al Qaeda's most formidable strongholds. It was the second U.S. attempt to free Somers in 10 days and Kerry said it had been approved because of information that Somers' life was in imminent danger. "It was our assessment that that clock would run out on Saturday," one U.S. official said. However, the Gift of the Givers relief group, which was trying to secure Korkie's release, said it had negotiated for the teacher to be freed and had expected that to happen on Sunday and for him to be returned to his family. Al Qaeda in the Arabian Peninsula (AQAP) is seen by Washington as one of al Qaeda's most dangerous branches. The United States has worked with Yemen's government and via drone strikes to attack its leaders in southern and eastern Yemen. "The callous disregard for Luke's life is more proof of the depths of AQAP's depravity, and further reason why the world must never cease in seeking to defeat their evil ideology," President Barack Obama said in a statement. Obama said he had authorized the operation and said the United States would "spare no effort to use all of its military, intelligence and diplomatic capabilities to bring Americans home safely, wherever they are located." SHOOT-OUT A U.S. defense official said about 40 U.S. special forces troops, flown in by tilt-rotor CV-22 Osprey aircraft, had advanced to within 100 meters (yards) of the walled compound where the hostages were held before the defenders were alerted and a firefight started. About 10 people, including al Qaeda guards and some civilians were killed in the fighting, said Ali al-Ahmadi, chief of Yemen's national security bureau. The Pentagon said it was unaware of any civilian casualties. U.S. officials said they knew Somers was at the location, partly because of information gleaned during the earlier rescue attempt, and they were aware that a second hostage was there but did not know in advance who it was. As the fight began, an al Qaeda guard darted inside the compound and then exited through the back. Gunfire was heard. That’s when American officials believe Somers and Korkie were shot. They were each shot several times, said the U.S. officials, who declined to be identified. The men were treated by medics but one died during the flight out and another aboard a U.S. ship. No U.S. troops were hurt, they said. The raid lasted about 30 minutes. Gift of the Givers said on its website: "We received with sadness the news that Pierre was killed in an attempt by American Special Forces, in the early hours of this morning, to free hostages in Yemen." It added: "The psychological and emotional devastation to (Korkie's wife) Yolande and her family will be compounded by the knowledge that Pierre was to be released by al Qaeda tomorrow ... Three days ago we told her 'Pierre will be home for Christmas'." Yolande, who was kidnapped with her husband in mid-2013, was released in January after intervention by Gift of the Givers. A South African government spokesman declined to comment. Militants in the region often demand millions of dollars for the release of hostages, including in the Korkies' case, and Saturday’s incident was likely to again raise discussion about the wisdom of paying ransoms. The United States, which refuses to make payments as they could encourage more kidnappings, is reviewing its approach to such cases but has said the payment ban will remain in place. There was no new information about three other hostages, a Briton, a Turk and a Yemeni, who had previously been held alongside Somers and Korkie, a Yemeni security official said. Lucy Somers, the photojournalist’s sister, told the Associated Press that she and her father learned of her brother's death from FBI agents at 0500 GMT (12 a.m. EST) Saturday. "We ask that all of Luke's family members be allowed to mourn in peace," she said from London. Somers had been in captivity for 15 months. IMMEDIATE DANGER Kerry said the decision to mount the raid was based on fears that AQAP planned to kill Somers. "Earlier this week, AQAP released a video announcing that Luke would be murdered within 72 hours. Along with other information, there was a compelling indication that Luke's life was in immediate danger," Kerry said. U.S. officials on Thursday said American forces had already attempted to rescue Somers, without giving details. Yemeni officials had previously disclosed the release of six Yemenis, a Saudi and an Ethiopian hostage in a raid on Nov. 25. A senior U.S. official said Yemeni President Abd Rabbu Mansour Hadi had given his support for Saturday's operation, which a U.S. official said took place at 1 a.m. local time. Yemen's government issued a different account of the incident. It said in a statement carried on state media that its security forces had led the raid. It said the security forces had surrounded the house and called on the kidnappers to surrender, but they instead shot the hostages. That led to an assault on the building in which four Yemeni security officers were also wounded, it said. The statement said the house belonged to suspected militant Saeed al-Daghaari, which another Yemeni security source told Reuters was in the village of Dafaar in the Wadi Abadan district of Shabwa. "It's a very small village with only 20-40 houses. There were very quick clashes with the gunmen and then it was all finished," a tribal source from the area said. AQAP on Thursday released a video showing a man it said was Somers saying: "I'm looking for any help that can get me out of this situation. I'm certain that my life is in danger." Reuters was not able to independently verify the authenticity of that video, which was reported by SITE Monitoring. (Additional reporting by Jeff Mason in Washington, Peter Salisbury in Sanaa, Yara Bayoumy in Manama, Phil Stewart in Kabul; Stella Mapenzauswa in Johannesburg; Writing by Angus McDowall and David Storey; Editing by Janet Lawrence, Mark Trevelyan, Grant McCool and Paul Simao) ||||| American photojournalist Luke Somers was killed by his al Qaeda captors during a failed U.S. rescue mission on December 5. Photo/Video: AP Under the cover of night, U.S. commandos approached the walled compound on foot, hoping to catch unawares the militants holding two hostages, including American Luke Somers. Then, less than 100 yards from their target, something went terribly wrong. A noise, maybe a dog bark, alerted the militants to the raiders, according to U.S. officials briefed on the operation. The rescue team’s biggest advantage—the element of surprise—was lost in that moment, and the shooting started. ...

– The US commandos who tried to rescue American Luke Somers in Yemen came agonizingly close to doing so, according to an account in the Wall Street Journal. It says that about 40 special-ops troops got to within 100 yards of the walled compound in silence about 1am local time. Then, "a noise, maybe a dog bark, alerted the militants to the raiders," writes Adam Entous, who spoke to US officials familiar with the rescue attempt. A 30-minute firefight ensued, during which officials think a militant from Al-Qaeda in the Arabian Peninsula slipped into the building where Somers was being held and shot him and South African hostage Pierre Korkie. The US troops killed about 10 militants and managed to escape with the two wounded hostages, but one died in the military aircraft carrying him away and the other died on an operating table. "The callous disregard for Luke's life is more proof of the depths of AQAP's depravity, and further reason why the world must never cease in seeking to defeat their evil ideology," said President Obama, as per Reuters. Obama approved the raid, the second in two weeks to try to free Somers, after AQAP promised to kill the photojournalist later today.

`` blazars '' comprise a sub - class of radio - loud agn showing a broad - band , double - humped spectral energy distribution ( sed ) . they differ from all other types of agn chiefly because of their extreme phenomelogical characteristics such as the extreme and broad - band flux density and polarisation variability , high degree of polarisation , fast superluminal motion and almost uniquely broad - band emission characteristics including a bright and highly variable component of @xmath0-ray emission @xcite . despite many efforts over the last decades , several key questions still remain unanswered in fully understanding the blazar phenomenon . for instance : * which are the dominant , broad - band emission processes involved ( synchrotron self - compton / inverse - compton ) ? * which mechanisms drive their often violent , broad - band variability ? ( e.g. relativistic shocks , colliding plasma shells or changing geometry due to helical / precessing jets ; see e.g. @xcite @xcite @xcite ) * what is the typical duty cycle of their activity ? * does the @xmath0-ray emission originate from the base / foot - point of the jet or further out in the same shocked regions as the radio cm / mm / sub - mm band emission ? observations that can ascertain whether a relationship exists between the @xmath0-ray and radio emission will be important for the effort to answer these questions . consequently , variability studies furnish important clues about the size , structure , physics and dynamics of the emitting region making agn / blazar monitoring programs of uttermost importance in providing the necessary constraints for understanding the origin of energy production . here , observations at short - mm / sub - mm bands are crucial , as they probe the innermost nuclear region and provide the important direct link between the longer wavelength radio bands and the more energetic ir / optical to @xmath0-ray regimes . until now , there has been no systematic long - term blazar monitoring program and detailed variability study at sub - mm bands . consequently , little is known about the variability characteristics of agn at sub - mm bands . important parameters which need to be determined are e.g. the variability amplitude and time scales and how the variability is related to other bands , e.g. correlation strengths and time lags . the knowledge of the variability behavior at sub - mm bands will thus better constrain the modeling of the variability and spectral evolution in the synchrotron branch of blazar seds . in this framework , we initiated a blazar monitoring program using the apex sub - mm telescope . the aim of this effort , which is part of the f - gamma program @xcite @xcite , is to perform the first long - term systematic study of blazar variability characteristics at sub - mm wavelengths . here we present first light curves and some preliminary results on the relative variability for our sample of sources . details including the full first years of data and analysis will be presented in fuhrmann et al . ( in prep . ) the apex 12 m sub - mm telescope is located at 5100 m altitude on llano chajnantor , chile . the observations are obtained with the laboca camera @xcite , which consists of 295 channels arranged in 9 concentric hexagons . laboca has a total field of view of 11.4 arcmin and allows observations in the 870 micrometer ( 345 ghz ) atmospheric window ( bandwidth : 60 ghz ) . the quasi - regular observations of our program started in 2008 and are performed during several dedicated mpi , swedish and eso apex laboca time - blocks per year . in addition , we are aiming at denser , more regular sampling through the regular and frequent pointing observations performed at apex since 2007 using our sources in the framework of other projects and apex technical time . observations within the f - gamma program are typically performed in _ spiral observing mode _ with a raster of four spirals of 20 or 35 seconds of integration each , depending on the source brightness at 345 ghz . at each run , skydip measurements for opacity correction and frequent calibrator measurements are performed . the number of observations per source range from 2 to 177 . .list of monitored sources . source class and 2fgl associations are taken from the second lat agn catalog @xcite . [ cols="<,<,<,<",options="header " , ] [ tab ] at apex , a sub - sample of 25 prominent , famous , frequently active and usually strong @xmath0-ray blazars from the f - gamma sample is observed together with a sample of 14 interesting southern hemisphere @xmath0-ray agn . the complete list of apex monitored sources is given in table 1 . some examples of source light curves are shown in figure 1 . all the monitored sources , except one , show excess variability ( over that expected from measurement noise ) . the exception is mkn 501 , which we exclude from the following variability analysis . for all the remaining 38 sources the @xmath1-analysis gives a probability of less than 0.1% that the observed variability is due to measurement noise . in a preliminary variability analysis , without taking the time sampling into account , the modulation index was calculated as @xmath2 . for most sources the modulation index is in the range 10 - 50 @xmath3 , but there is a tail in the distribution which extends up to @xmath4 as shown in figure 2 . the mean and median modulation indexes are 37 and 31% respectively . a number of sources show variations by a factor of 10 or more between minimum and maximum flux . this is significantly larger than at the longer cm- and also short - mm bands . the variability is in general also faster and more directly correlated with the high energy emission@xcite . this is most likely an effect of opacity / synchrotron self - absorption increasing towards the longer radio wavelengths and indicates that the sub - mm emission regions are more co - spatial with the optical/@xmath0-ray ones . in an analysis of the spectral evolution observed by the cm / mm f - gamma program @xcite , it has been shown that the radio flares and multi - frequency variability can be well described by only two physical processes : ( i ) achromatic variability ( possibly related to helical or precessing jets ) or ( ii ) evolving synchrotron flares or shocks inside the relativistic jets ( as described in e.g. @xcite . in such synchrotron scenario of evolving agn outbursts , the flux - density variability first appears at higher frequencies ( ir / optical / uv / x - ray ) and then propagates through the spectrum towards longer wavelengths . the formation and evolution of shocks is expected to start at high synchrotron frequencies during their growth stage where the synchrotron self - absorption peak moves to lower frequencies while the peak flux and variability amplitude is increasing ( mm / sub - mm bands ) up to the plateau stage , followed by a subsequent decay stage ( cm - bands ) . here , the variability in the sub - mm band is expected to be much more pronounced and faster than at longer cm - radio bands@xcite . this was confirmed to 1 mm wavelength by the earlier observations ( fuhrmann et al . in prep . ) : the mean strength of variability ( modulation index ) steadily increases from 9.5% at 110 mm to 30% at 1 mm . our new laboca observations imply that this trend continues into the sub - mm band . according to the three different regimes of shock evolution ( growth , plateau , decay ) , such continued increase ( or flattening ) would then indicate that , on average , flares reach their plateau / decay phase at sub - mm bands well before they do at cm bands . a more extensive analysis and discussion of the variability properties will be presented in a forthcoming paper . 99 ackermann , m. , et al . , astrophys . j. , 743 , 171 ( 2011 ) angelakis , e. , et al . , memorie della societa astronomica italiana , 79 , 1042 ( 2008 ) angelakis , e. , et al . , arxiv1111.6992a ( 2011 ) camenzind , m. & krockenberger , m , a&a , 255 , 59 ( 1992 ) fuhrmann , l. , et al . , aip conf . 921 , 249 ( 2007 ) guetta , d. , ghisellini , g. , lazzati , d. , & celotti , a. , a&a , 421 , 877 ( 2004 ) larsson , s. , fuhrmann , l. et al . , in preparation marscher , a. p. , in asp conf . ser . 100 : energy transport in radio galaxies and quasars , 100 , 45 ( 1996 ) marscher , a. p. and gear , w. k. , astrophys . j. , 298 , 114 ( 1985 ) siringo , g. , et al . , a&a , 497 , 945 ( 2009 ) urry , c. m. , astroparticle physics , 11 , 159 ( 1999 ) valtaoja , e. , et al . , a&a , 254 , 71 ( 1992 )

so far , no systematic long - term blazar monitoring programs and detailed variability studies exist at sub - mm wavelengths . here , we present a new sub - mm blazar monitoring program using the apex 12-m telescope . a sample of about 40 @xmath0-ray blazars has been monitored since 2007/2008 with the laboca bolometer camera at 345ghz . first light curves , preliminary variability results and a first comparison with the longer cm / mm bands ( f - gamma program ) are presented , demonstrating the extreme variability characteristics of blazars at such short wavelengths .

Bigger breasts mean bigger tips, and other "scientific" studies from 2010. Corbis A t its best, scientific research yields new discoveries and innovations, from the double helix to better cancer treatments. But sometimes it simply serves to confirm the obvious. Here are seven studies that did just that in 2010: 1. Bigger breasts make for bigger tips Last spring, Cornell professor Michael Lynn published "Determinants and Consequences of Female Attractiveness and Sexiness: Realistic Tests with Restaurant Waitresses" in the Archives of Sexual Behavior. The study found that waitresses with bigger breasts got bigger tips, as did those who were slender and blonde. While the study's findings didn't exactly break any new ground, Lynn said "it's always important to test what seems like obvious cultural wisdom." His colleagues weren't so impressed. "I am disappointed but not surprised to learn that female servers with larger breasts receive more generous tips," said Professor Sherry F. Colb. 2. Men never stop wanting sex In December, Australian scientists reported that sex was important for nearly half of men aged 75 to 95, and many wanted it more often than they were getting it. Judith Kuriansky, a clinical psychologist and Columbia University adjunct, wasn't too surprised by the findings. "Men who are over 75 are not over the hill anymore," she told MSNBC. 3. Little boys like cars In April, researchers from London's City University announced at the British Psychological Society's annual conference what many parents have long known: Young boys intrinsically like cars, while girls like dolls. That's "obvious" said Colleen Egan at Parent Dish. 4. Appearances matter for female musicians In April, researcher Noola Griffiths published a study titled "'Posh music should equal posh dress': an investigation into the concert dress and physical appearance of female soloists" in Psychology of Music, detailing how she'd found that what female musicians wear affects how audiences perceive their performance (Lady Gaga might have told her that). "The results are predictable but the context is interesting," says Ben Goldacre in The Guardian. 5. Performance-enhancing drugs enhance performance Scores of "performance-enhancing" Olympians over the years weren't wrong. According to a study by the World Anti-Doping Agency, injections of testosterone and human growth hormones help athletes go faster. "This is helpful in showing those skeptics out there who say it doesn't help performance," the agency's director general said. It's the "most obvious study ever," said Chris Chase at Yahoo! Sports. 6. Men are more likely to pick up female hitchhikers with large breasts Not only do bigger breasts make for bigger tips, they can be helpful to female hitchhikers looking for a ride. According to a French study, "Bust size and hitchhiking: a field study," male drivers are nearly 10 percent more likely to pick up a woman with a C cup versus an A cup. "I suppose that we could have all predicted this fact albeit it is fun to see it tested in a scientific manner," said Gad Saad, Ph.D. in Psychology Today. 7. Everybody's working for the weekend In January, the Journal of Social and Clinical Psychology published "Weekends, Work, and Well-Being: Psychological Need Satisfactions and Day of the Week Effects on Mood, Vitality, and Physical Symptoms," a study that presented a truth most of us know all too well: We feel our best from Friday night to Sunday afternoon and our worst while at work. "Science confirm the obvious" here, said Popular Science. ||||| Along with some truly groundbreaking discoveries, scientists this year told us a few things we already kind of knew. Here are some of the ultimate "well, duh" findings of 2010: Meth can harm an unborn child. Turns out, it's not a great idea for a gal with a bun in the oven to shoot up with methamphetamine. The study, published in the March 17 issue of The Journal of Neuroscience, showed children whose moms abuse meth while pregnant had brain abnormalities that were possibly more severe than those of kids exposed to alcohol prenatally. Perhaps not everyone was aware: Of the more than 16 million Americans over the age of 12 who have used meth, about 19,000 are pregnant women, according to data from the National Surveys on Drug Use and Health. But wait, there's some substance here: Identifying the vulnerable brain structures may help predict particular learning and behavioral problems in meth-exposed children, the researchers said. Bullies pick on unpopular kids. Who'd have guessed? Bullies target kids who are unpopular and less likely to be defended by their peers, a new study finds. And in elementary school, which this study focused on, kids are only interested in what their same-sex peers think. So, boys will target classmates who are not well-liked by other boys, regardless of what the girls think. Same went for girl bullies. In that way the bullies could gain status by dominating other kids while also staying in the good graces of the in-group. While the findings are a no-brainer, they do paint a picture of a young, yet strategic, bully who goes out of his or her way to ensure success when taunting, hitting, making fun of and other bully behaviors. "Bullies do it so strategically that if there is not a good program at the school nothing will change. They won't change their behavior by themselves, because it gives them a lot of advantages," said lead researcher René Veenstra, professor of sociology at the University of Groningen. "You really need a good program that changes the attitude of all the kids in the classroom that makes clear to children that if they want the bully to stop they all have to be part, take joint action." Veenstra and colleagues detailed their findings in the March/April issue of the journal Child Development. Smoking a lot of weed is bad for you. Marijuana use can cause mess up your head, suggests a study presented this year at the meeting for the Society of Neuroscience. Results showed the more marijuana a person used the greater difficulty they had in focus and attention In the study, participants had to complete a card-sorting task in which they were shown four cards that differed in color, symbol and value. Based on the rules they gleaned from the displayed cards, they had to sort a deck of cards. Participants were only told whether their sorting attempts were correct or not. Habitual marijuana users made repeated errors despite feedback that they were wrong. Marijuana users also had more difficulty maintaining a set of rules when sorting, suggesting an inability to maintain focus. Those participants who began using marijuana before the age of 16, and those who used the most marijuana, showed the greatest impairment. Friendless kids are sad. That's essentially what a three-year study of 130 girls and 101 boys in third through fifth grades found. Compared with friendless children, those who had pals were less likely to report depressed feelings. Particularly for those shy and withdrawn kids, having a friend seemed to stave off the blues. "Having one friend can be protective for withdrawn or shy kids," said lead author William M. Bukowski, a psychology professor and director of the Concordia Centre for Research in Human Development. "Our study confirms the value of having friends, which are like a shield against negative social experiences." Guys prefer casual sex to dating. Why in the world would a guy rather have a fling than a series of dates where commitment may be involved? A study out this year in the journal Sex Roles suggests it comes down to context. While overall numbers showed both genders preferred traditional dating to hooking up, of those college students who strongly preferred traditional dating, there were significantly more women than men (41 percent versus 20 percent). Of those who preferred casual sex, there were far fewer women than men (2 percent versus 17 percent). When participants were asked to consider the possibility of a long-term relationship, both guys and gals preferred dating over hooking up. However, when that relationship possibility wasn't mentioned, men chose hooking up and women dating. Guys also indicated that even with hook-ups (which are meant to be string-free), they feared their casual-sex partners would seek a relationship. Women indicated the opposite, wanting a relationship and worrying about becoming too attached to a noncommittal other. Who knew? Sitting in front of the TV all day can make a teen fat. Too much television, video games and Internet can increase body fat in teens, according to a five-year study of 744 adolescents published in the American Journal of Epidemiology. And, yes, the reason could have to do with sitting on your butt more during free time than being active. And, yes, those teens who showed an increase in screen time over the study period had the worst body-fat outcomes. "Our findings show that youth are at greater risk of increased body fat if screen use increases through high school," said lead author Tracie A. Barnett, a professor at the Université de Montréal's Department of Social and Preventive Medicine and a scientist at the Sainte-Justine Hospital Research Center. "One possible reason is that teens who increase their screen time are simultaneously reducing involvement in, and opportunities for, more active pursuits." Teens who decreased veg-out time during the study showed the healthiest body-fat profiles. Novel way to lose weight: Eat less and exercise more. Shortly after the year started, in early January, Australian researchers announced the only reliable way to lose weight was to eat less, exercise, or do both. But the eye-rolling should be directed toward the magical, fat-burning promises made by some products and eaten up by some consumers. The researchers intended to disprove the idea that a person can lose weight by simply tricking his or her body into burning calories from fat, not carbohydrates, and thus make stored fat evaporate. Their study showed that mice, genetically altered to burn fats rather than carbohydrates, had body compositions similar to that of normal mice. That's because their bodies simply converted the unused carbs into stored fat. "Our data urges a correction in people's concept of a magic bullet — something that will miraculously make them thin while they sit on the couch watching television," said Greg Cooney, one of the study researchers and a scientist at Sydney's Garvan Institute for Medical Research. Caffeine affects kids' sleep. That stuff we drink in the morning to stay alert seems to do just that. Kids who consume caffeine sleep less, and the more they consume, the less they sleep, a study found. A survey of children's snack and beverage consumption revealed that kids ages 8 to 12 took in the equivalent of nearly three cans of caffeinated soda per day. They also slept an average of 8.47 hours per night, less than is recommended by the Centers for Disease Prevention and Control (CDC). The survey, conducted by William Warzak, a psychology professor at the University of Nebraska Medical Center, and colleagues, queried parents of 200 children ages 5 to 12. Despite caffeine’s diuretic effect, the kids who drank it didn’t appear prone to bed-wetting. Kids who study abroad drink more alcohol. Hey, parents, if you send your kids abroad (to study), a pond away from parental guidance and punishment, they're going to live a little. In October, researchers reported in the journal Psychology of Addictive Behaviors that students doubled how much they drank while they were away, upping their consumption from about four alcoholic drinks per week while at home to about eight weekly drinks abroad. The findings also support the idea that students younger than 21, the legal drinking age in the United States, take advantage of relaxed drinking laws abroad. The underage students in the study nearly tripled their drinking, whereas students over 21 doubled their intake of alcohol. Kids raised by gay couples do just fine in school. So lesbian and gay parents aren't harmful to their kids ... really? A study published in August in the journal Demography found that children being raised by same-sex couples have nearly the same educational achievement as children raised by married heterosexual couples. This finding should be among the most no-duh announcements out there. However, that is not the case, as many remain convinced, against all available evidence, that gay parents are dangerous to children Stanford sociologist Michael Rosenfeld used the 2000 Census to figure out rates at which children repeated a grade during elementary or middle school. Nearly 7 percent of children raised by heterosexual married couples were held back a year, while about 9.5 percent of children living with same-sex partners repeated a grade. In fact children of gay and married heterosexual couples were less likely to be held back than their peers raised by opposite-sex unmarried couples and single parents. Another study out this year, this one a review of past research, also suggested kids raised by lesbians do just fine. You can follow LiveScience Managing Editor Jeanna Bryner on Twitter @jeannabryner.

– This year there were groundbreaking discoveries ... and then there were these gems. LiveScience compiles 10 of the most "duh" scientific findings of the year: Meth is bad for your unborn child: A shocking study published in The Journal of Neuroscience found that kids born to moms who used meth while pregnant had brain abnormalities that could be worse than those of kids whose moms drank while pregnant. Bullies target unpopular kids: A study published in the journal Child Development informed us that bullies mess with unpopular kids whose peers are less likely to come to their aid. Friendless kids are blue: A three-year study of 231 elementary school kids found that kids who had friends were less likely to report depressed feelings than those without. Guys prefer casual sex to dating more than women do: The journal Sex Roles rocked our world with the finding that when having to choose between traditional dating and casual sex, only 2% of women picked casual sex, compared to 17% of men. Click for more, including the astonishing conclusion that teens who sit on their butt in front of the TV all day can become fat. And click here for seven more duh findings, several of which involve boobs.

SECTION 1. EXPANSION OF TRANSIT OPERATING ASSISTANCE GRANT PROGRAM. Section 5307(b) of title 49, United States Code, is amended-- (1) in paragraph (1)-- (A) in subparagraph (D), by striking ``of less than 200,000'' and inserting ``of-- ``(i) less than 200,000; ``(ii) not less than 200,000, and less than 400,000, if the State or regional authority providing public transportation for the area operates at least 100 buses in fixed-route service in the area during peak service hours; ``(iii) not less than 400,000, and less than 600,000, if the State or regional authority providing public transportation for the area operates at least 100 buses in fixed- route service in the area during peak service hours; ``(iv) not less than 600,000, and less than 800,000, if the State or regional authority providing public transportation for the area operates at least 100 buses in fixed-route service in the area during peak service hours; ``(v) not less than 800,000, and less than 1,000,000, if the State or regional authority providing public transportation for the area operates at least 100 buses in fixed-route service in the area during peak service hours; and ``(vi) not less than 1,000,000, if the State or regional authority providing public transportation for the area operates at least 100 buses in fixed-route service in the area during peak service hours;''. (2) in paragraph (2)-- (A) by striking subparagraphs (B) through (D); and (B) by redesignating subparagraph (E) as subparagraph (B); (3) by redesignating paragraph (3) as paragraph (6); and (4) by inserting after paragraph (2) the following: ``(3) Limitations on use of funds.--A designated recipient may use-- ``(A) not more than 50 percent of the funds made available to the designated recipient under this section for activities described in paragraph (2)(D)(iii); ``(B) not more than 45 percent of the funds made available to the designated recipient under this section for activities described in paragraph (2)(D)(iv); ``(C) not more than 40 percent of the funds made available to the designated recipient under this section for activities described in paragraph (2)(D)(v); ``(D) not more than 35 percent of the funds made available to the designated recipient under this section for activities described in paragraph (2)(D)(vi); and ``(E) not more than 30 percent of the funds made available to the designated recipient under this section for activities described in paragraph (2)(D)(vii). ``(4) Conditional use of funds in an urbanized area with a population of at least 200,000.-- ``(A) In general.--For each of fiscal years 2010 through 2015 and subject to subparagraph (B), a designated recipient may use a percentage of the funds made available to the designated recipient under this section, in addition to the percentage described in paragraph (3), to finance the operating costs of equipment and facilities for use in public transportation in an urbanized area with a population of not less than 200,000. ``(B) Operating cost.--To be eligible under subparagraph (A), the designated recipient's percentage of revenue for the operating cost of equipment and facilities for use in public transportation from non- Federal sources (excluding farebox revenue) must be greater than such revenue from the previous fiscal year. ``(C) Limitation.--The amount available for a grant under this paragraph shall not exceed the percentage of such increase. ``(5) TIGGER grant.-- ``(A) In general.--In addition to any other grant under this section, the Secretary may award a grant, from any funds that may be made available to carry out this section for each of fiscal years 2010 through 2015, to a designated recipient for the operating cost of equipment and facilities for use in public transportation in an urbanized area with a population of 200,000 or more, if the designated recipient-- ``(i) was awarded a grant under the Transit Investments for Greenhouse Gas and Energy Reduction program, established under the ninth proviso under the heading `transit capital assistance' under the heading `Federal Transit Administration' under the heading `DEPARTMENT OF TRANSPORTATION' of title XII of division A of the American Recovery and Reinvestment Act of 2009 (Public Law 111-105; 123 Stat. 210); and ``(ii) demonstrates that the designated recipient has achieved-- ``(I) total energy savings of not less than 10 percent, as a result of a project funded using a grant under the Transit Investments for Greenhouse Gas and Energy Reduction program; ``(II) energy savings of not less than 10 percent, as a percentage of the total energy usage of the public transit agency, as a result of a project funded using a grant under the Transit Investments for Greenhouse Gas and Energy Reduction program; or ``(III) total greenhouse gas emission reduction of not less than 10 percent as a result of a project funded using a grant under the Transit Investments for Greenhouse Gas and Energy Reduction program. ``(B) Funds.--The Secretary shall use not less than 10 percent of the funds made available to carry out this section for grants under this paragraph.''.

Expands the urbanized area formula grants program to include public transit projects in urbanized areas with specified population ranges if the state or regional authority that provides public transportation for the area operates less than 100 buses in fixed-route service in the area during peak service hours. Separates population categories by graduated increases of 200,000, starting with between 200,000 and 400,000, and capping at a minimum of 1 million. Establishes certain grant use limits for the operating costs of public transportation equipment and facilities in such projects, beginning with 50% of grant funds for certain activities and declining gradually to 30% for certain other activities. Revises grant eligibility requirements for FY2010-FY2015 for such projects in urbanized areas with a population of at least 200,000. Authorizes the Secretary of Transportation, during FY2010-FY2015, to award an additional grant to a designated recipient for the operating cost of public transportation equipment and facilities under this Act if the recipient: (1) was awarded a grant under the Transit Investments for Greenhouse Gas and Energy Reduction (TIGGER) program; and (2) demonstrates that it has achieved specified energy savings and total greenhouse gas emission reduction as a result of a TIGGER grant project.

the stars themselves are mysterious enough to study . w uma - type contact binaries ( cbs ) are , in many respects , excellent objects to research , being among the most observed stars and having experienced mass transfer between components . the observational data of individual systems and statistical properties of entire data show so many regular and irregular variations that many contradictory ideas concerning their structure and evolution have been perpetuated . recently , yildiz & doan ( 2013 , hereafter paper i ) have discovered a new method to compute the initial masses of component stars from the observed masses and luminosity of the secondary component . this method gives the initial mass range for the secondaries as @xmath0=1.3 - 2.6 m_@xmath1 . that of the primaries is @xmath2 , which is in very good agreement with the required mass range for the angular momentum loss process via magnetic braking ( tutukov , dremova & svechnikov 2004 ) . moreover , the initial masses of a- and w - subtypes have completely different ranges for their secondaries : @xmath3 for the former and @xmath4 for the latter . in the present study , we further discuss some results of paper i and develop new methods for estimation of age and angular momentum loss rates in detached and cb phases . the formation history of a - subtype cbs is controlled in the pre - contact phase by two effects , namely , nuclear evolution of the massive component ( @xmath0=1.8 - 2.7 m@xmath5 ) and angular momentum evolution of the lighter component ( @xmath6=0.2 - 1.5 m@xmath5 ) . depending on the initial masses and angular momentum reservoir , the detached phase ends up near the terminal - age of the main - sequence ( tams ) line in the hertzsprung@xmath7russel diagram ( hrd ) . in the precursors of w - subtype cbs , however , both components experience efficient angular momentum loss throughout or during part of their main - sequence ms phase of the massive component . for some of their progenitors , angular momentum evolution is so fast that the components may come into contact with each other before the massive component becomes a tams star . the maximum mass of their massive components is @xmath8 m@xmath5 . in addition , for stars with @xmath9 m@xmath5 the secondary star is not effective in angular momentum loss process in the early detached phase of binary evolution , but becomes effective as its convective zone deepens during evolution towards the tams line in the hrd . for a typical a - subtype cb , the total initial mass is @xmath10= 3.0 m@xmath5 . the mean initial masses of the secondary and primary components are @xmath11 and @xmath12=1.0 m@xmath5 , respectively . the mean total initial mass of w - subtype , however , is @xmath13=2.5 , 0.5 m@xmath5 less than that of a - subtype cbs . for w - subtype cbs , @xmath14 m@xmath5 and @xmath15 m@xmath5 . age determination of w uma - type cbs is very important for a better understanding of binary evolution . in addition to initial masses , if period ( @xmath16 ) or orbital dimension is estimated at the time of the first overflow ( fof ) , for example , one can compute initial angular momentum and then deduce the rate of angular momentum loss as a first approximation . a similar computation can also be made for the mass - loss . the present study also aims to make such computations . binaries have a variety of periods . if one of the components is a late - type star in the detached phase , then angular momentum loss causes the orbital period to decrease . if both components are late - type , then angular momentum evolution is nearly twice as fast . this may be the reason why w uma - type cbs are observed in relatively young open clusters , such as in praesepe . angular momentum evolution is one of the essential problems in stellar astrophysics and has been the subject of many papers on single or binary stars in the literature ( van t veer 1991 ; eggleton , 2001 ; demircan et al . 2006 ; stpie , 2006 ; gazeas & stpie 2008 ) . although magnetic braking and tidal locking in binaries with late - type components are very complicated processes , the angular momentum loss rates for such binaries derived by stpie ( 2006 , see also gazeas & stpie 2008 ) and demircan et al . ( 2006 ) are very easy to apply . we compare our results on angular momentum evolution of the detached precursors of w uma - type cbs with these rates ( see section 4.2 ) . the final end stage of evolution of w uma - type cbs is also debated in the literature ( see , e.g. , li et al . 2007 ; eker , demircan & bilir 2008 ) . the fate of a w uma - type cb essentially depends on the ratio of angular momentum and mass - loss during the contact phase . these systems seem to be the progenitors of blue stragglers observed in many clusters . some of the blue stragglers are single stars and it seems reasonable to suppose that these were formed by merging components of w uma - type cbs . in this case , the rate of angular momentum loss is so high that the components merge . on the other hand , if mass - loss rate is very high , then the component stars remain separate . the final form will then consist of either two brown dwarfs ( li et al . 2007 ) or two stars with very low mass . in the latter case , the age of the stars becomes infinitely long . in order to predict the final products , further studies are required for mass and angular momentum loss rates in the w uma - type cb phase . the remainder of this paper is organized as follows . in section 2 , some basic results of paper i are summarized and the @xmath17 relation for w uma - type cbs is compared with that of the well - known detached eclipsing binaries ( debs ) . section 3 is devoted to the method for age computation of a- and w - subtype cbs and a comparison of results with cluster member close binaries . orbital parameters of cbs and their evolution are considered and discussed in section 4 . finally , our concluding remarks are given in section 5 . the secondary components of the w uma - type cbs are over - luminous and over - sized according to their masses . in paper i , yildiz and doan consider this to be a result of the initial masses being much higher than the present ( observed ) masses . they define @xmath18 of a secondary star as the mass according to its observed luminosity ( @xmath19 ) by assuming @xmath20 : @xmath21 . they construct interior models with mass - loss by using the mesa stellar evolution code ( paxton et al . 2011 ) and find a relation between the mass differences @xmath22 and @xmath23 , where @xmath24 is the present mass of the secondaries . the expression derived from these models for initial mass of the secondary components in paper i is a function of the mass difference @xmath25 and @xmath24 : @xmath26 , where the masses are in units of solar mass . we want to test if @xmath18 is successful in predicting the present radii . @xmath27 of a- and w - subtypes are plotted with respect to @xmath24 and @xmath18 in figs . 1(a ) and ( b ) . we use the same data set as in paper i. the components of well - known debs are also shown for comparison ( southworth , debcat : http://www.astro.keele.ac.uk / jkt / debcat/ ) . the secondary components are very large for their mass @xmath24 . hilditch , king & mcfarlane ( 1988 ) have found that the radii of secondaries of the w - subtype cbs are 1.5 times larger than normal . although they have reported much larger factors for the secondaries of a - subtype cbs , we find that the difference between the radii of the secondaries and normal stars is simply 0.5 r_@xmath1 . for example , a normal star of 0.4 m_@xmath1 has a radius of 0.4 r_@xmath1 ( cu cnc ) , but the radius of a secondary component in an a - subtype cb of the same mass ( aq psc ) is 0.9 r_@xmath1 . for w - subtype , there is no such single relation but a decreasing difference as mass increases . the relation between @xmath27 and @xmath18 , however , is very close to the @xmath28 relation for the components of debs . this is a very good indicator for the fact that the entire structure of a secondary star with @xmath18 is very close to that of a single star with mass @xmath29 . this result is somewhat surprising because one may expect that the oversized behaviour of a secondary star is mainly determined by the presence of a close companion . the slight differences between the @xmath17 relation for both a- and w - subtypes and the @xmath28 relation for debs are noticeable for low mass secondaries ( @xmath30 , @xmath31 ) . this is most likely due to the influence of a very close companion ( @xmath32 d and @xmath33 ) on the secondary radius . in the light of these results we assume that the secondaries internal structure is similar to that of a star with the mass @xmath34 . if these stars were isolated with their present features , then their ms lifetime would be given by @xmath18 rather than @xmath35 . this point has strong significance for our method to compute the ages of w uma - type cbs ( see section 3 ) . it is well known that the gravitational force between two masses depends on the product of their masses and the inverse square of the distance between them . we have the initial masses but not the distances between the component stars in their detached phase . therefore , we consider the product of initial masses ( @xmath36 ) as a measure of tidal interaction . in fig . 2(a ) this product for a- and w - subtypes is plotted with respect to the primary present mass @xmath37 . the solid line is for the curve fitted to the data . the present mass of the primary components is strongly dependent on their initial masses . the other parameters @xmath7 such as initial angular momentum , period and age of systems @xmath7 have no role . in fig . 2(b ) , the total initial mass is plotted against @xmath38 . there is a very clear linear relation between @xmath39 and @xmath38 . the fitting line is found as @xmath40 . @xmath38 can be computed from this equation as a function of initial masses ( in solar mass ) : @xmath41 the maximum difference between the observed and computed @xmath38 from equation ( 1 ) is less than 10 per cent . this implies that the mass of the primary either remains constant or changes very little during the w uma phase . in fig . 3 , the total initial mass @xmath39 is plotted against the present total mass @xmath42 . the relation between @xmath39 and @xmath43 is also linear . the mean difference between @xmath39 and @xmath43 is 1.05 m@xmath5 for a- and 0.82 m@xmath5 for w - subtype cbs . this shows that the a - subtype cbs have lost , on average , a mass 0.23 m@xmath5 higher than w - subtype cbs . the data are a bit more scattered in fig . 3 than in fig . this implies that @xmath24 also depends on some other initial parameters as well as initial masses ( see section 4 ) . age of a normal star can be found by some methods based on comparison of a computer model and observational parameters . time variation of stellar parameters allows such methods . for a normal ms star with non - astreoseismic constraints , the highest ( and monotonic ) changing ( observable ) parameters are luminosity and radius . however , these parameters are a very sensitive function of mass , and composition . if uncertainty in mass is high , then an accurate age is difficult to obtain . if the uncertainty in mass is about 10 per cent , then age uncertainty is about 30 per cent . in comparison , the effect of metallicity on age is greater . for example , a 1.5 m_@xmath1model with solar composition ( x=0.7024 , z=0.0172 ) has an ms lifetime of 2.1 gyr . in comparison when z=0.0322 , the age for a star of the same mass is 3.2 gyr , a 50 per cent longer ms lifetime . therefore , any ages we find and estimate have some inherent uncertainty . on the other hand , even in the cases where we fit interior models to asteroseismic constraints to find an age the agreement with other derived ages can be poor . for alpha centauri a and b , for example , ages from the non - asteroseismic and asteroseismic constraints are found as about 9 gyr and 5.6 - 5.9 gyr ( see , miglio & montalban 2005 ; yildiz 2007a ) , respectively . therefore , even with the best state - of - the - art observational results there can still be some dispute or uncertainty about the age of a star , this is compounded in the case of binary stars where binary interactions will make it difficult to determine the true age . this is in addition to the effect of uncertain current / initial stellar composition . below , we therefore aim to develop a method for determination of the age of observed w uma binaries in terms of the variable of stellar mass only to yield a rough , but useful , stellar age . as stated by hilditch , king & mcfarlane ( 1988 ) , the secondaries of a - subtype cbs are more evolved than that of w - subtype cbs . then , we anticipate that the detached phases of precursors of a- and w - subtype cbs are quite different . the secondary stars at the end of this phase may overflow their roche lobe for two very different reasons : + ( i ) due to rapid expansion after tams or \(ii ) due to the roche lobe receding as a result of rapid orbital ( angular momentum ) evolution . + in case ( i ) , the detached phase lasts about @xmath44 of the secondary star . this is simply the formation course of a - subtype . since @xmath45 for a - subtype , the duration of the detached phase ( @xmath46 ) is less than @xmath47 . in case ( ii ) , angular momentum loss rate is high because both components are effective in the detached phase . this occurs in the precursors of w - subtype cbs . their detached phase is shorter than the ms lifetime of their secondaries , @xmath48 . the shortest value of @xmath46 for w - subtype with @xmath49 is @xmath50 ( see below ) . if @xmath0 is higher than 1.8 @xmath51 , then only the primary component is effective in the angular momentum loss process via magnetic braking . such binaries become a - subtype . since their angular momentum evolution is relatively slow , the roche lobe overflow merely starts ( i.e. mass transfer ) after the secondary component completes its ms lifetime . the mass transfer process obscures stellar quantities such as age . therefore , it seems to be very difficult to assign age to the w uma - type cbs as they have three different evolutionary phases - namely , detached , semidetached ( sd ) and cb phases . current age of a cb system ( @xmath52 ) is the summation of durations of three phases . they are detached ( @xmath46 ) , sd ( @xmath53 ) and contact phases ( @xmath54 ) . then , @xmath55 where @xmath54 is the time from the beginning of contact phase until present . as stated above , for a - subtype cbs , the time interval for the detached phase is very nearly the same as the ms lifetime of the secondary star : @xmath56 . one can precisely compute @xmath44 as a function of @xmath0 . yildiz ( 2013 ) derives an expression for @xmath44 from stellar evolution models as @xmath57 the detached phase of the precursor of an a - subtype system lasts slightly longer than the ms lifetime of its massive component [ @xmath58 . this time interval is very short for systems with high initial mass . on the other hand , the age of a system with a secondary of mass @xmath34 must be less than @xmath59 , or , more generally , @xmath60 ( see below ) . from these constraints , we can derive an expression for @xmath61 . after the detached phase , nuclear and secular evolution develop under control of each other . the sd phase starts with @xmath0 and @xmath18 is the present presumptive mass according to luminosity . the upper limit for these binaries , however , is the ms age of a star with a mass of @xmath62 . the ms age of such an isolated star is @xmath63 . in general , @xmath64 . perhaps , the most convenient age can be found by using the mean mass of the secondary components during binary evolution : @xmath65 then , we can take @xmath61 as @xmath66 if we insert @xmath67 and equation ( 5 ) in equation ( 2 ) , we find the age of an a - subtype cb : @xmath68 the results of this simple method are listed in table a1 . the basic properties of these binaries are given in paper i. although age of a cb is a very complicated problem and may be computed in a variety of ways , the present method gives reasonable results . the average age for the a - subtype cbs is 4.37 gyr . this value is , surprisingly , in very good agreement with the age found for a - type cbs by bilir et al . ( 2005 ) , 4.48 gyr . the results are listed in table 1 . in table a1 , uncertainties in ages of cbs are also listed . these uncertainties are derived from equation ( 6 ) : @xmath69 the uncertainty in @xmath70 as a function of @xmath71 and @xmath72 is given in equation 11 of paper i. the mean uncertainty given in table 1 is the average of the uncertainties in age of individual binaries listed in table a1 . .mean ages of a- and w - subtype cbs . the ages taken from bilir et al . ( 2005 ) are the mean kinematical ages . [ cols="<,^,^",options="header " , ] in our w uma data sample , four binaries are cluster member . the ages of these binaries are given in table 2 . if we compare the ages of binaries with those of clusters , we notice that the cluster age is very low for tx cnc . this system is perhaps the youngest of the whole data set . the age we find for qx and , however , is twice the cluster age . for the other two binary systems , the age differences seem acceptable . for ah vir , for example , the differences between the three ages are less than 8 per cent . therefore , it should be stated that our method for age computation is better for a - subtype than for w - subtype . this is in contrast to the result obtained from comparison of our results with the data of the close binaries in clusters ( see section 3.3 ) . the greatest difference appears for the youngest system tx cnc . such exceptional binaries must either have very low angular momentum or very high angular momentum loss rate , or both . however , we notice that the difference between the age of the present study and the cluster age depends on @xmath6 : the smaller the value of @xmath6 , the greater is the difference ( @xmath73 ) . with respect to @xmath74 , in units of solar radius . @xmath75 . the fitted line is @xmath76 . , width=291 ] with respect to @xmath16 , in units of day . @xmath77 d. , width=291 ] for the computation of mean angular momentum and mass - loss rates in cbs , semimajor axis @xmath74 and @xmath16 are required at a certain time , in addition to the initial masses of the components . @xmath74 can be computed from the expression for the effective radius of roche lobe given by eggleton ( 1983 ) . it seems reasonable to assume that , at least for a - subtypes , the mass transfer starts when the massive component of the detached phase fills its roche lobe the first time . this point is known as the fof . then , the roche lobe radius can be taken as @xmath78 . the distance between the component stars at fof is @xmath79 note that @xmath80 . the values of @xmath81 found from equation ( 9 ) are plotted with respect to the present @xmath74 in fig . @xmath81 ranges from 7 to 11 @xmath82 and has a mean value of @xmath83 . there is a weak correlation between @xmath81 and the present @xmath74 . using kepler s third law @xmath84 the period ( @xmath85 ) at the end of the pre - contact phase is available . @xmath85 given in equation ( 10 ) is in units of days and plotted with respect to the present period @xmath16 in fig . @xmath85 ranges from 1.24 to 2 d , except two a - subtype systems . the mean value of @xmath85 is about 1.6 d. although there is no correlation between @xmath85 and @xmath16 confirmed for the full range , there is an inverse relation for small values of @xmath16 ( @xmath86 ) . @xmath85 and @xmath81 are given in table a1 . for w - subtypes , the values should be considered as just upper limits . assuming components as point masses , the orbital angular momentum of a binary is given by @xmath87 where masses are in units of slar masses and @xmath16 in units of day . the angular momentum at the time of the fof ( @xmath88 ) can be computed from equation ( 11 ) by using initial masses , and @xmath85 . @xmath89 is plotted with respect to the present angular momentum @xmath90 in fig . 7 . there is a power - law relation between @xmath88 and @xmath91 . the solid line is the fitting line . the slope in fig . 7 is 0.46 , which implies that @xmath92 . that is to say , the present angular momentum depends on angular momentum at the time of the fof : @xmath93 for systems with the lowest angular momentum , @xmath94 . this means that the present angular momentum of these systems is one tenth of @xmath88 . for systems with the highest angular momentum , however , @xmath95 . in this case , the present angular momentum is two fifths of @xmath88 . with respect to @xmath90 , in cgs units . the fitted line is @xmath96 , width=291 ] in fig . 8 , logarithmic change in angular momentum is plotted with respect to logarithmic change in mass of the secondaries . it seems that the present mass of the secondary stars is determined by the amount of angular momentum loss after fof . angular momentum loss rate in any phase of a binary system depends on its mass - loss rate and angular momentum content . in fig . 9 , angular momentum of a - subtype cbs at different evolutionary phases is plotted with respect to the total initial mass ( @xmath39 ) . the a - subtype cbs have lost a large part of their angular momentum and therefore take place in the lower part of fig . 9 . in fig . 9 , their angular momentum at the time of the fof ( @xmath88 ) is also plotted . on average , these binaries have lost 78 per cent of their @xmath88 ( the range 55@xmath790 per cent ) during the sd and contact phases ; the larger the angular momentum is , the higher is the loss rate . following several attempts , we derive a fitting formula for the angular momentum after fof as a function of initial masses : @xmath97 where masses are in solar masses . similarly , we derive another fitting formula for mass - loss : @xmath98 and @xmath99 , respectively . note that dj / dt and dm / dt are multiplied by @xmath100 . , width=291 ] the angular momentum and mass - loss rates are plotted with respect to @xmath0 in fig . 10 . we note that these two formulae are very strong functions of @xmath0 as luminosity . this may imply that nuclear evolution of @xmath0 dominates orbital evolution mainly driven by @xmath6 . our present consideration does not allow for consideration of the sd and cb phases separately . the angular momentum and mass - losses should be estimated in order to ascertain the final product of w uma - type cbs . a study of near - cbs could help with this . we compute typical angular momentum ( @xmath101 ) in order to assess angular momentum evolution of precursors of a - subtype cbs in the detached phase.the angular momentum is a function of the total mass @xmath39 in all phases . angular momentum loss in the detached phase , however , depends on the convective structure of the primary components with a mass of @xmath6 . therefore , we assume that the loss rate ( @xmath102/@xmath103 ) is a function of @xmath6 : @xmath104 where @xmath105 and @xmath106 are free parameters to be determined from fitting @xmath107 to the angular momentum of the well - known debs ( @xmath108 ) , @xmath109 then , we find the expression for @xmath107 in terms of @xmath88 and @xmath6 : @xmath110 the unit of @xmath105 is the same as the angular momentum . if we take @xmath6 and @xmath44 in units of solar mass and in units of year , respectively , we find the value of @xmath105 and @xmath106 by fitting @xmath107 to the angular momentum of debs as @xmath111 ( cgs ) and @xmath112 : @xmath113 the dotted and solid lines in fig . 9 represent the fitting lines for the debs and detached progenitors of w uma binaries , respectively . they are very close to each other . the progenitors of a - subtype cbs have lost 13@xmath740 per cent of their initial angular momentum during the detached phase , with a mean value of 29 per cent . however , most of their angular momentum is lost during the sd and cb phases . the total angular momentum lost by the progenitors of the a - subtype cbs overall phases is about 84 per cent , i.e. the initial angular momentum of these binaries was six to seven times greater than their present angular momentum . the mean values of @xmath114 and @xmath115 are found from @xmath101 given in equation ( 17 ) as 16.3 r_@xmath1 and 4.5 d , respectively . while @xmath114 ranges from 13.3 to 19.7 r_@xmath1 , the interval for @xmath115 is from 2.8 to 6.3 d. @xmath114 and @xmath115 are given in table a1 . it is well known that the angular momentum loss rate for early - type stars is very slow in comparison with late - type stars . therefore , the rate we derive for the detached phase of a - subtype cbs is only a function of the mass of their late - type component ( @xmath6 ) . stpie ( 2006 ) gives the rate for close binaries as ( see also gazeas & stpie 2008 ) @xmath116 where masses and radii are in solar units , period is in days , time in years and angular momentum in cgs units . equation ( 19 ) is a semi - empirical formula based on the angular momentum rate of single late - type stars . the expression we derive is much easier than that of stpie ( 2006 ) . the mean ratio of the rate given in equation ( 18 ) to that of equation ( 19 ) for the detached phase is 0.63 , which is satisfactory agreement . if we compute the initial angular momentum by going back from fof , the initial angular momentum difference between the two rates is about 10 per cent . demircan et al . ( 2006 ) derive the time variation of angular momentum for detached chromospherically active binaries ( cabs ) as @xmath117 we also compare our results with that given by equation ( 20 ) . the mean ratio of the rate given in equation ( 18 ) to that of equation ( 20 ) is 0.77 for the detached phase . many of the cabs studied by demircan et al . are not in the initial mass range of w uma - type cbs . despite this fact , the agreement between the two rates is very impressive . the rate given in equation ( 18 ) is found from fitting the initial angular momentum of a - subtype to that of the well - known detached binaries with a period less than 5 d. in order to obtain better agreement between this rate and that of demircan et al . ( 2006 ) , the upper limit for the period should be reduced to 4.45 d. then , @xmath118 ( cgs ) for this upper limit . this may imply that , in addition to the constraints on the initial masses of the components , the detached binaries with @xmath119 d become a - subtype cbs . in paper i , a new method is developed for estimating initial masses of component stars in w uma - type cbs , based on introducing mass according to the luminosity of the secondaries . in the present study , it is shown that an additional clue is the @xmath120 relation for secondary stars to support the idea that the structure and evolution of these stars primarily depend on @xmath34 : @xmath17 relation being in good agreement with that of normal stars of detached binaries . using the initial mass and mass according to luminosity , a new method is developed for age estimation of a- and w - subtypes . this is the first time that such a method of age estimation for w uma - type cbs has been derived from the fundamental properties of secondary components . we apply this method and find that the mean ages of a- and w - subtypes are 4.4 and 4.6 gyr , respectively . these values are in very good agreement with the kinematic ages found by bilir et al . ( 2005 ) . the ages we find are also compared with the ages of cluster member close binaries . the agreement is satisfactory for stellar age , provided that the binary is not very young . our data sample contains four cluster member w uma - type cbs ; two a- and two w - subtypes . the ages we find are in good agreement with the cluster ages , if @xmath6 is about 1 m_@xmath1 . the difference is great for the cbs with @xmath121 m_@xmath1 . determination of stellar parameters of such cluster member binaries is very important for our understanding of binary evolution . we show that there is a strong correlation between the present mass of primary ( @xmath122 ) and the total initial mass ( @xmath39 ) . if we estimate ( @xmath122 ) from this , the difference between the observed and the estimated values of @xmath122 is very small , being less than 10 per cent . this implies that @xmath122 either remains constant or changes very little during the w uma phase , if at all . the discovery of initial masses of w uma - type cbs in terms of observed quantities leads us to consider the binary evolution of these systems . we compute the properties of a - subtype cbs at the time of the fof by using eggleton s ( 1983 ) expression for the effective radius of roche lobe . the mean distance between the component stars in the former case is about @xmath123 r_@xmath1 and the mean period is @xmath77 d. computation of the period or mean distance enables us to also consider the angular momentum evolution of these systems . we find that angular momentum at fof is 2.5@xmath710 times greater than the present angular momentum . that is to say , these systems have lost a great deal of their angular momentum during the contact phase ( sd+cb ) . for estimation of initial angular momentum in the detached phase , we compare @xmath88 with the angular momentum of the well - known debs . satisfactory agreement is obtained if the rate of angular momentum loss in the detached phase is directly proportional to @xmath124 . the rate we derive is in very good agreement with the rates of stpie ( 2006 ) and demircan et al . we find that @xmath125 r_@xmath1 and @xmath126 d. in addition to the initial mass intervals for the components of w uma - type cbs , we also obtain an upper limit for the initial period . i would like to thank ros elliot for her help in checking the language of the manuscript . # 1#2apj , # 1 , # 2 # 1#2aj , # 1 , # 2 # 1astro - ph/ # 1 # 1#2phys . , # 1 , # 2 # 1#2phys . rep . , # 1 , # 2 # 1#2rev . # 1 , # 2 # 1#2phys . today . , # 1 , # 2 # 1#2phys . rev . , a # 1 , # 2 # 1#2a&a , # 1 , # 2 # 1#2a&ar , # 1 , # 2 # 1#2 ap&ss , # 1 , # 2 # 1#2a&as , # 1 , # 2 # 1#2ara&a , # 1 , # 2 # 1#2phys . fluids , # 1 , # 2 # 1#2apjs , # 1 , # 2 # 1#2pasj , # 1 , # 2 # 1#2mnras , # 1 , # 2 # 1ibvs , no . # 1 99 bilir s. , karata y. , demircan o. , eker z. , 2005 , mnras , 357 , 497 bukowiecki l. , maciejewski g. , konorski p. , errmann r. , 2012 , inf . bull . stars , 6021 , 1 demircan o. , eker z. , karata y. , bilir s. , 2006 , mnras , 366 , 1511 eggleton p.p . , 1983 , apj , 268 , 368 eggleton p.p . , 2001 , in podsiadlowski ph . , rappaport s. , king a.r . , dantona f. , burder l. , eds , asp conf . vol.229 , evolution of binary and multiple star systems , astron . , san francisco , p. 157 eker z. , demircan o. , bilir s. , 2008 , mnras , 386 , 1756 gazeas k. , stpie k. , 2008 , mnras , 390 , 1577 hilditch r.w . , king d.j . , mcfarlane t.m . , 1988 , mnras , 231 , 341 li l. , zhang f. , han z. , jiang d. , 2007 , apj , 662 , 596 stpie k. , 2006 , acta astron . , 56 , 347 tutukov a.v . , dremova g.n . , svechnikov m.a . , 2004 , , 48 , 219 van t veer f. , 1991 , a&a , 250,84 yildiz m. , 2013 , submitted yildiz m. , doan t. , 2013 , mnras , 430 , 2029 lcccccccccccccc@ + star & type & @xmath74 & @xmath16 & @xmath37 & @xmath35 & @xmath127&@xmath128&@xmath18 & @xmath52 & @xmath129 & @xmath81 & @xmath85 & @xmath130 & @xmath131 + & & ( r_@xmath1 ) & ( d ) & ( m_@xmath1 ) & ( m_@xmath1 ) & ( m_@xmath1 ) & ( m_@xmath1 ) & ( m_@xmath1 ) & ( gyr ) & ( gyr)&(r_@xmath1 ) & ( d ) & ( r_@xmath1 ) & ( d ) + + star & type & @xmath74 & @xmath16 & @xmath37 & @xmath35 & @xmath6&@xmath0&@xmath18 & @xmath52 & @xmath129 & @xmath81 & @xmath85 & @xmath130 & @xmath131 + & & ( r_@xmath1 ) & ( d ) & ( m_@xmath1 ) & ( m_@xmath1 ) & ( m_@xmath1 ) & ( m_@xmath1 ) & ( m_@xmath1 ) & ( gyr ) & ( gyr)&(r_@xmath1 ) & ( d ) & ( r_@xmath1 ) & ( d ) + hv uma & a & 4.988 & 0.711 & 2.80@xmath132 0.60 & 0.50@xmath132 0.17 & 2.11@xmath132 0.57 & 2.54@xmath132 0.69 & 1.30@xmath132 0.12 & 1.62@xmath132 1.89 & 0.48 & 8.48 & 1.33 & 13.80 & 2.75 + v376 and & a & 5.364 & 0.799 & 2.49@xmath132 0.06 & 0.76@xmath132 0.03 & 1.90@xmath132 0.10 & 2.51@xmath132 0.13 & 1.40@xmath132 0.02 & 1.58@xmath132 0.35 & 0.30 & 8.57 & 1.38 & 13.77 & 2.82 + rr cen & a & 4.110 & 0.606 & 2.09@xmath132 0.43 & 0.45@xmath132 0.10 & 1.50@xmath132 0.25 & 2.21@xmath132 0.38 & 1.10@xmath132 0.04 & 2.53@xmath132 1.77 & 0.89 & 8.03 & 1.37 & 15.04 & 3.51 + v921 her & a & 5.288 & 0.877 & 2.07@xmath132 0.05 & 0.51@xmath132 0.03 & 1.37@xmath132 0.05 & 2.61@xmath132 0.09 & 1.34@xmath132 0.00 & 1.50@xmath132 0.20 & 0.20 & 9.66 & 1.75 & 13.32 & 2.83 + uz leo & a & 4.192 & 0.618 & 1.99@xmath132 0.04 & 0.60@xmath132 0.02 & 1.40@xmath132 0.04 & 2.35@xmath132 0.07 & 1.24@xmath132 0.01 & 2.00@xmath132 0.24 & 0.82 & 8.67 & 1.53 & 13.99 & 3.13 + v535 ara & a & 4.209 & 0.629 & 1.94@xmath132 0.04 & 0.59@xmath132 0.02 & 1.25@xmath132 0.07 & 2.64@xmath132 0.15 & 1.39@xmath132 0.06 & 1.41@xmath132 0.39 & 0.77 & 10.00 & 1.86 & 13.34 & 2.86 + aq tuc & a & 4.102 & 0.595 & 1.93@xmath132 0.21 & 0.69@xmath132 0.08 & 1.42@xmath132 0.20 & 2.22@xmath132 0.32 & 1.22@xmath132 0.03 & 2.31@xmath132 1.33 & 0.95 & 8.18 & 1.42 & 14.80 & 3.46 + ef dra & a & 3.041 & 0.424 & 1.81@xmath132 0.00 & 0.29@xmath132 0.00 & 1.28@xmath132 0.00 & 1.86@xmath132 0.00 & 0.84@xmath132 0.00 & 4.63@xmath132 0.00 & 2.76 & 7.11 & 1.24 & 19.56 & 5.66 + v2388 oph & a & 4.681 & 0.802 & 1.80@xmath132 0.02 & 0.34@xmath132 0.01 & 1.12@xmath132 0.02 & 2.35@xmath132 0.04 & 1.12@xmath132 0.01 & 2.14@xmath132 0.16 & 0.29 & 9.18 & 1.73 & 13.77 & 3.17 + aw uma & a & 3.024 & 0.439 & 1.79@xmath132 0.14 & 0.14@xmath132 0.01 & 1.13@xmath132 0.02 & 2.11@xmath132 0.03 & 0.90@xmath132 0.00 & 3.26@xmath132 0.17 & 2.51 & 8.24 & 1.52 & 15.10 & 3.78 + v776 cas & a & 3.063 & 0.440 & 1.75@xmath132 0.04 & 0.24@xmath132 0.02 & 1.14@xmath132 0.05 & 2.05@xmath132 0.08 & 0.91@xmath132 0.01 & 3.47@xmath132 0.59 & 2.48 & 7.99 & 1.47 & 15.74 & 4.05 + v592 per & a & 4.519 & 0.716 & 1.74@xmath132 0.06 & 0.68@xmath132 0.04 & 1.29@xmath132 0.10 & 2.03@xmath132 0.15 & 1.13@xmath132 0.01 & 3.01@xmath132 0.88 & 0.47 & 7.70 & 1.36 & 16.41 & 4.23 + xz leo & a & 3.456 & 0.488 & 1.74@xmath132 0.05 & 0.59@xmath132 0.03 & 1.26@xmath132 0.06 & 2.03@xmath132 0.10 & 1.08@xmath132 0.00 & 3.11@xmath132 0.59 & 1.83 & 7.75 & 1.38 & 16.30 & 4.21 + dk cyg & a & 3.345 & 0.471 & 1.74@xmath132 0.00 & 0.53@xmath132 0.00 & 1.24@xmath132 0.00 & 2.01@xmath132 0.00 & 1.04@xmath132 0.00 & 3.29@xmath132 0.00 & 2.04 & 7.69 & 1.37 & 16.54 & 4.32 + nn vir & a & 3.540 & 0.481 & 1.73@xmath132 0.02 & 0.85@xmath132 0.02 & 1.36@xmath132 0.06 & 1.95@xmath132 0.08 & 1.20@xmath132 0.01 & 3.18@xmath132 0.53 & 1.91 & 7.30 & 1.26 & 18.09 & 4.90 + @xmath133 cra & a & 3.697 & 0.591 & 1.72@xmath132 0.04 & 0.22@xmath132 0.02 & 1.06@xmath132 0.03 & 2.18@xmath132 0.06 & 0.98@xmath132 0.00 & 2.83@xmath132 0.28 & 0.97 & 8.66 & 1.64 & 14.44 & 3.53 + rz tau & a & 3.111 & 0.416 & 1.70@xmath132 0.16 & 0.64@xmath132 0.06 & 1.21@xmath132 0.14 & 2.10@xmath132 0.25 & 1.14@xmath132 0.03 & 2.76@xmath132 1.33 & 2.92 & 8.07 & 1.46 & 15.37 & 3.84 + v401 cyg & a & 3.800 & 0.583 & 1.68@xmath132 0.00 & 0.49@xmath132 0.00 & 1.09@xmath132 0.00 & 2.24@xmath132 0.00 & 1.13@xmath132 0.00 & 2.40@xmath132 0.00 & 1.02 & 8.79 & 1.65 & 14.20 & 3.40 + aq psc & a & 3.267 & 0.476 & 1.68@xmath132 0.03 & 0.39@xmath132 0.02 & 1.18@xmath132 0.04 & 1.89@xmath132 0.07 & 0.91@xmath132 0.00 & 4.27@xmath132 0.59 & 1.98 & 7.33 & 1.32 & 18.45 & 5.25 + ah aur & a & 3.290 & 0.494 & 1.68@xmath132 0.05 & 0.28@xmath132 0.01 & 1.10@xmath132 0.02 & 2.01@xmath132 0.04 & 0.91@xmath132 0.01 & 3.63@xmath132 0.31 & 1.76 & 7.93 & 1.47 & 16.03 & 4.22 + v839 oph & a & 2.987 & 0.409 & 1.64@xmath132 0.00 & 0.50@xmath132 0.00 & 1.18@xmath132 0.00 & 1.88@xmath132 0.00 & 0.97@xmath132 0.00 & 4.08@xmath132 0.00 & 3.05 & 7.33 & 1.32 & 18.49 & 5.27 + fp boo & a & 3.774 & 0.640 & 1.61@xmath132 0.05 & 0.15@xmath132 0.02 & 0.96@xmath132 0.03 & 2.09@xmath132 0.06 & 0.89@xmath132 0.00 & 3.36@xmath132 0.39 & 0.72 & 8.51 & 1.65 & 14.90 & 3.82 + v1073 cyg & a & 4.595 & 0.786 & 1.60@xmath132 0.02 & 0.51@xmath132 0.01 & 1.00@xmath132 0.01 & 2.29@xmath132 0.03 & 1.17@xmath132 0.00 & 2.21@xmath132 0.13 & 0.32 & 9.21 & 1.79 & 13.90 & 3.31 + ex leo & a & 2.859 & 0.409 & 1.57@xmath132 0.03 & 0.31@xmath132 0.02 & 1.07@xmath132 0.05 & 1.80@xmath132 0.08 & 0.83@xmath132 0.01 & 5.12@xmath132 0.93 & 3.06 & 7.21 & 1.32 & 19.72 & 5.99 + ap leo & a & 2.965 & 0.430 & 1.46@xmath132 0.04 & 0.43@xmath132 0.02 & 1.00@xmath132 0.06 & 1.80@xmath132 0.11 & 0.89@xmath132 0.02 & 4.83@xmath132 1.18 & 2.65 & 7.33 & 1.37 & 19.23 & 5.84 + fg hya & a & 2.344 & 0.328 & 1.45@xmath132 0.03 & 0.16@xmath132 0.01 & 0.90@xmath132 0.02 & 1.79@xmath132 0.04 & 0.74@xmath132 0.00 & 5.66@xmath132 0.50 & 5.31 & 7.46 & 1.44 & 18.89 & 5.80 + ux eri & a & 3.070 & 0.445 & 1.43@xmath132 0.03 & 0.53@xmath132 0.02 & 1.00@xmath132 0.05 & 1.80@xmath132 0.10 & 0.94@xmath132 0.01 & 4.65@xmath132 1.02 & 2.40 & 7.30 & 1.37 & 19.41 & 5.92 + yy crb & a & 2.659 & 0.377 & 1.43@xmath132 0.03 & 0.35@xmath132 0.01 & 0.93@xmath132 0.02 & 1.85@xmath132 0.05 & 0.87@xmath132 0.01 & 4.61@xmath132 0.46 & 3.80 & 7.65 & 1.47 & 17.73 & 5.19 + ck boo & a & 2.452 & 0.355 & 1.42@xmath132 0.00 & 0.15@xmath132 0.00 & 0.85@xmath132 0.00 & 1.84@xmath132 0.00 & 0.76@xmath132 0.00 & 5.16@xmath132 0.00 & 4.40 & 7.78 & 1.53 & 17.51 & 5.17 + v566 oph & a & 2.785 & 0.410 & 1.40@xmath132 0.03 & 0.33@xmath132 0.01 & 0.82@xmath132 0.01 & 2.06@xmath132 0.03 & 0.96@xmath132 0.00 & 3.31@xmath132 0.21 & 3.04 & 8.72 & 1.76 & 14.87 & 3.92 + tyc1174 a & a & 2.642 & 0.389 & 1.38@xmath132 0.01 & 0.26@xmath132 0.01 & 0.83@xmath132 0.02 & 1.90@xmath132 0.04 & 0.85@xmath132 0.01 & 4.41@xmath132 0.39 & 3.50 & 8.07 & 1.61 & 16.47 & 4.69 + cn hyi & a & 2.927 & 0.456 & 1.37@xmath132 0.06 & 0.25@xmath132 0.02 & 0.79@xmath132 0.07 & 1.98@xmath132 0.16 & 0.88@xmath132 0.05 & 3.88@xmath132 1.48 & 2.24 & 8.48 & 1.72 & 15.45 & 4.23 + gr vir & a & 2.399 & 0.347 & 1.37@xmath132 0.16 & 0.17@xmath132 0.06 & 0.81@xmath132 0.10 & 1.83@xmath132 0.23 & 0.76@xmath132 0.02 & 5.25@xmath132 2.63 & 4.65 & 7.81 & 1.56 & 17.54 & 5.24 + dz psc & a & 2.481 & 0.366 & 1.35@xmath132 0.06 & 0.18@xmath132 0.02 & 0.80@xmath132 0.03 & 1.83@xmath132 0.08 & 0.77@xmath132 0.01 & 5.22@xmath132 0.87 & 4.08 & 7.85 & 1.57 & 17.45 & 5.22 + hn uma & a & 2.515 & 0.383 & 1.28@xmath132 0.06 & 0.18@xmath132 0.01 & 0.75@xmath132 0.02 & 1.76@xmath132 0.06 & 0.74@xmath132 0.01 & 5.93@xmath132 0.83 & 3.65 & 7.70 & 1.56 & 18.46 & 5.80 + v410 aur & a & 2.432 & 0.366 & 1.27@xmath132 0.06 & 0.17@xmath132 0.03 & 0.74@xmath132 0.05 & 1.75@xmath132 0.11 & 0.73@xmath132 0.01 & 6.06@xmath132 1.52 & 4.07 & 7.70 & 1.57 & 18.56 & 5.87 + sx crv & a & 2.160 & 0.317 & 1.25@xmath132 0.04 & 0.10@xmath132 0.01 & 0.72@xmath132 0.02 & 1.68@xmath132 0.05 & 0.66@xmath132 0.01 & 7.32@xmath132 0.97 & 5.75 & 7.44 & 1.52 & 20.33 & 6.86 + eq tau & a & 2.481 & 0.341 & 1.22@xmath132 0.03 & 0.54@xmath132 0.02 & 0.91@xmath132 0.06 & 1.47@xmath132 0.09 & 0.82@xmath132 0.01 & 8.56@xmath132 2.04 & 4.84 & 6.24 & 1.17 & 35.53 & 15.92 + y sex & a & 2.657 & 0.420 & 1.21@xmath132 0.15 & 0.22@xmath132 0.03 & 0.64@xmath132 0.05 & 1.91@xmath132 0.15 & 0.83@xmath132 0.03 & 4.38@xmath132 1.44 & 2.84 & 8.68 & 1.86 & 15.62 & 4.48 + v2357 oph & a & 2.670 & 0.416 & 1.19@xmath132 0.01 & 0.29@xmath132 0.01 & 0.72@xmath132 0.02 & 1.68@xmath132 0.04 & 0.76@xmath132 0.00 & 6.47@xmath132 0.62 & 2.92 & 7.47 & 1.53 & 20.10 & 6.74 + v404 peg & a & 2.679 & 0.419 & 1.18@xmath132 0.00 & 0.29@xmath132 0.00 & 0.67@xmath132 0.00 & 1.82@xmath132 0.00 & 0.82@xmath132 0.00 & 5.06@xmath132 0.00 & 2.85 & 8.17 & 1.72 & 16.93 & 5.12 + qx and & a & 2.617 & 0.412 & 1.18@xmath132 0.17 & 0.24@xmath132 0.04 & 0.61@xmath132 0.05 & 1.92@xmath132 0.17 & 0.85@xmath132 0.03 & 4.29@xmath132 1.58 & 3.00 & 8.81 & 1.90 & 15.48 & 4.43 + vz lib & a & 2.380 & 0.358 & 1.06@xmath132 0.06 & 0.35@xmath132 0.03 & 0.60@xmath132 0.05 & 1.71@xmath132 0.13 & 0.80@xmath132 0.02 & 6.00@xmath132 1.89 & 4.30 & 7.92 & 1.70 & 18.51 & 6.07 + oo aql & a & 3.329 & 0.507 & 1.05@xmath132 0.02 & 0.88@xmath132 0.02 & 0.91@xmath132 0.23 & 1.30@xmath132 0.33 & 1.01@xmath132 0.05 & 9.75@xmath132 9.25 & 1.62 & 5.61 & 1.04 & 64.99 & 40.89 + v508 oph & a & 2.383 & 0.345 & 1.01@xmath132 0.00 & 0.52@xmath132 0.00 & 0.68@xmath132 0.00 & 1.51@xmath132 0.00 & 0.83@xmath132 0.00 & 7.90@xmath132 0.00 & 4.72 & 6.91 & 1.42 & 26.47 & 10.67 + dx tuc & a & 2.396 & 0.377 & 1.00@xmath132 0.03 & 0.30@xmath132 0.01 & 0.49@xmath132 0.02 & 1.81@xmath132 0.06 & 0.82@xmath132 0.01 & 5.06@xmath132 0.67 & 3.78 & 8.85 & 2.01 & 16.16 & 4.96 + tv mus & a & 2.510 & 0.446 & 0.94@xmath132 0.14 & 0.13@xmath132 0.02 & 0.34@xmath132 0.02 & 1.91@xmath132 0.12 & 0.79@xmath132 0.03 & 4.55@xmath132 1.34 & 2.40 & 10.31 & 2.56 & 15.20 & 4.58 + xy boo & a & 2.227 & 0.371 & 0.93@xmath132 0.34 & 0.15@xmath132 0.05 & 0.32@xmath132 0.02 & 1.98@xmath132 0.15 & 0.83@xmath132 0.00 & 4.03@xmath132 1.13 & 3.96 & 10.89 & 2.75 & 15.07 & 4.48 + tz boo & a & 1.790 & 0.298 & 0.72@xmath132 0.05 & 0.15@xmath132 0.04 & 0.28@xmath132 0.04 & 1.47@xmath132 0.19 & 0.59@xmath132 0.03 & 11.05@xmath132 5.80 & 6.58 & 8.57 & 2.20 & 20.56 & 8.17 + ah cnc & a & 2.553 & 0.360 & 1.47@xmath132 0.15 & 0.25@xmath132 0.03 & 0.93@xmath132 0.08 & 1.85@xmath132 0.16 & 0.82@xmath132 0.03 & 4.81@xmath132 1.78 & 4.24 & 7.65 & 1.47 & 17.70 & 5.17 + rt lmi & a & 2.656 & 0.375 & 1.31@xmath132 0.05 & 0.48@xmath132 0.03 & 0.88@xmath132 0.07 & 1.75@xmath132 0.13 & 0.90@xmath132 0.01 & 5.18@xmath132 1.54 & 3.84 & 7.35 & 1.42 & 19.74 & 6.27 + dn cam & w & 3.668 & 0.498 & 1.85@xmath132 0.02 & 0.82@xmath132 0.02 & 1.50@xmath132 0.07 & 1.86@xmath132 0.09 & 1.15@xmath132 0.01 & 1.26@xmath132 0.37 & 1.71 & 6.82 & 1.13 & 13.81 & 3.25 + v728 her & w & 3.183 & 0.471 & 1.65@xmath132 0.00 & 0.30@xmath132 0.00 & 1.01@xmath132 0.00 & 2.19@xmath132 0.00 & 1.02@xmath132 0.00 & 1.80@xmath132 0.00 & 2.03 & 8.78 & 1.68 & 13.80 & 3.32 + v402 aur & w & 3.766 & 0.604 & 1.64@xmath132 0.05 & 0.33@xmath132 0.02 & 1.01@xmath132 0.03 & 2.21@xmath132 0.08 & 1.04@xmath132 0.01 & 1.84@xmath132 0.25 & 0.90 & 8.86 & 1.70 & 13.85 & 3.33 + ef boo & w & 3.220 & 0.430 & 1.61@xmath132 0.00 & 0.82@xmath132 0.00 & 1.25@xmath132 0.00 & 1.90@xmath132 0.00 & 1.05@xmath132 0.00 & 1.95@xmath132 0.00 & 2.66 & 7.27 & 1.28 & 13.33 & 3.18 + et leo & w & 2.670 & 0.347 & 1.59@xmath132 0.02 & 0.54@xmath132 0.01 & 1.25@xmath132 0.05 & 1.55@xmath132 0.05 & 0.79@xmath132 0.00 & 2.03@xmath132 0.58 & 4.67 & 6.07 & 1.03 & 12.71 & 3.14 + aa uma & w & 3.400 & 0.468 & 1.56@xmath132 0.00 & 0.85@xmath132 0.00 & 1.21@xmath132 0.00 & 1.88@xmath132 0.00 & 0.99@xmath132 0.00 & 2.15@xmath132 0.00 & 2.07 & 7.26 & 1.29 & 13.22 & 3.17 + yy eri & w & 2.553 & 0.321 & 1.55@xmath132 0.14 & 0.62@xmath132 0.07 & 1.24@xmath132 0.53 & 1.53@xmath132 0.45 & 0.78@xmath132 0.03 & 2.20@xmath132 5.57 & 5.57 & 6.01 & 1.02 & 12.66 & 3.13 + er ori & w & 3.224 & 0.423 & 1.53@xmath132 0.00 & 0.98@xmath132 0.00 & 1.27@xmath132 0.00 & 1.74@xmath132 0.00 & 1.05@xmath132 0.00 & 2.29@xmath132 0.00 & 2.77 & 6.70 & 1.16 & 13.07 & 3.15 + v502 oph & w & 3.162 & 0.453 & 1.51@xmath132 0.28 & 0.56@xmath132 0.08 & 1.12@xmath132 0.23 & 1.73@xmath132 0.36 & 0.93@xmath132 0.04 & 2.39@xmath132 2.57 & 2.29 & 6.88 & 1.24 & 12.69 & 3.10 + v870 ara & w & 2.681 & 0.400 & 1.50@xmath132 0.01 & 0.12@xmath132 0.01 & 0.91@xmath132 0.02 & 1.89@xmath132 0.04 & 0.77@xmath132 0.00 & 2.44@xmath132 0.26 & 3.25 & 7.85 & 1.52 & 12.75 & 3.15 + bb peg & w & 2.676 & 0.362 & 1.42@xmath132 0.02 & 0.55@xmath132 0.01 & 1.07@xmath132 0.03 & 1.59@xmath132 0.04 & 0.87@xmath132 0.00 & 2.91@xmath132 0.42 & 4.21 & 6.43 & 1.16 & 12.29 & 3.06 + vy sex & w & 3.014 & 0.443 & 1.42@xmath132 0.02 & 0.45@xmath132 0.01 & 0.99@xmath132 0.02 & 1.73@xmath132 0.04 & 0.87@xmath132 0.00 & 2.91@xmath132 0.30 & 2.43 & 7.09 & 1.33 & 12.44 & 3.08 + v417 aql & w & 2.687 & 0.370 & 1.40@xmath132 0.00 & 0.50@xmath132 0.00 & 0.98@xmath132 0.00 & 1.74@xmath132 0.00 & 0.90@xmath132 0.00 & 3.05@xmath132 0.00 & 3.96 & 7.11 & 1.33 & 12.44 & 3.08 + ae phe & w & 2.698 & 0.362 & 1.38@xmath132 0.06 & 0.63@xmath132 0.02 & 1.02@xmath132 0.14 & 1.69@xmath132 0.18 & 0.87@xmath132 0.03 & 3.20@xmath132 1.62 & 4.18 & 6.86 & 1.26 & 12.39 & 3.07 + ez hya & w & 2.958 & 0.450 & 1.37@xmath132 0.00 & 0.35@xmath132 0.00 & 0.85@xmath132 0.00 & 1.89@xmath132 0.00 & 0.89@xmath132 0.00 & 3.14@xmath132 0.00 & 2.34 & 7.96 & 1.57 & 12.68 & 3.16 + ah vir & w & 2.797 & 0.407 & 1.36@xmath132 0.00 & 0.41@xmath132 0.00 & 0.94@xmath132 0.00 & 1.67@xmath132 0.00 & 0.82@xmath132 0.00 & 3.35@xmath132 0.00 & 3.08 & 6.95 & 1.31 & 12.18 & 3.05 + v842 her & w & 2.817 & 0.419 & 1.36@xmath132 0.00 & 0.35@xmath132 0.00 & 0.84@xmath132 0.00 & 1.90@xmath132 0.00 & 0.89@xmath132 0.00 & 3.08@xmath132 0.00 & 2.86 & 8.04 & 1.60 & 12.70 & 3.17 + uv lyn & w & 2.878 & 0.415 & 1.36@xmath132 0.02 & 0.50@xmath132 0.01 & 0.92@xmath132 0.02 & 1.80@xmath132 0.05 & 0.93@xmath132 0.01 & 3.32@xmath132 0.32 & 2.93 & 7.47 & 1.43 & 12.51 & 3.11 + w uma & w & 2.568 & 0.334 & 1.35@xmath132 0.09 & 0.69@xmath132 0.05 & 0.99@xmath132 0.24 & 1.77@xmath132 0.32 & 0.91@xmath132 0.04 & 3.44@xmath132 2.23 & 5.09 & 7.24 & 1.36 & 12.54 & 3.10 + qw gem & w & 2.557 & 0.358 & 1.31@xmath132 0.04 & 0.44@xmath132 0.01 & 0.90@xmath132 0.03 & 1.66@xmath132 0.06 & 0.83@xmath132 0.01 & 3.79@xmath132 0.64 & 4.31 & 6.97 & 1.33 & 12.08 & 3.04 + ss ari & w & 2.758 & 0.406 & 1.31@xmath132 0.00 & 0.40@xmath132 0.00 & 0.84@xmath132 0.00 & 1.78@xmath132 0.00 & 0.87@xmath132 0.00 & 3.65@xmath132 0.00 & 3.11 & 7.57 & 1.49 & 12.35 & 3.10 + v752 cen & w & 2.588 & 0.370 & 1.30@xmath132 0.00 & 0.40@xmath132 0.00 & 0.84@xmath132 0.00 & 1.76@xmath132 0.00 & 0.85@xmath132 0.00 & 3.84@xmath132 0.00 & 3.97 & 7.47 & 1.47 & 12.27 & 3.09 + am leo & w & 2.656 & 0.366 & 1.29@xmath132 0.01 & 0.59@xmath132 0.01 & 0.94@xmath132 0.03 & 1.64@xmath132 0.04 & 0.90@xmath132 0.00 & 3.99@xmath132 0.36 & 4.09 & 6.82 & 1.29 & 12.10 & 3.04 + v781 tau & w & 2.844 & 0.408 & 1.29@xmath132 0.07 & 0.57@xmath132 0.03 & 0.94@xmath132 0.08 & 1.61@xmath132 0.13 & 0.89@xmath132 0.01 & 3.99@xmath132 1.19 & 3.08 & 6.70 & 1.26 & 12.03 & 3.03 + v1191 cyg & w & 2.182 & 0.313 & 1.29@xmath132 0.08 & 0.13@xmath132 0.01 & 0.71@xmath132 0.01 & 1.85@xmath132 0.03 & 0.76@xmath132 0.00 & 3.85@xmath132 0.21 & 5.88 & 8.19 & 1.70 & 12.44 & 3.18 + rz com & w & 2.476 & 0.339 & 1.23@xmath132 0.09 & 0.55@xmath132 0.04 & 0.89@xmath132 0.12 & 1.58@xmath132 0.23 & 0.89@xmath132 0.03 & 4.61@xmath132 2.34 & 4.93 & 6.68 & 1.28 & 11.84 & 3.01 + gm dra & w & 2.303 & 0.339 & 1.21@xmath132 0.04 & 0.22@xmath132 0.02 & 0.67@xmath132 0.02 & 1.83@xmath132 0.07 & 0.79@xmath132 0.00 & 3.76@xmath132 0.49 & 4.92 & 8.25 & 1.74 & 12.36 & 3.19 + fu dra & w & 2.170 & 0.307 & 1.17@xmath132 0.04 & 0.29@xmath132 0.01 & 0.70@xmath132 0.02 & 1.68@xmath132 0.05 & 0.76@xmath132 0.01 & 4.81@xmath132 0.51 & 6.17 & 7.51 & 1.55 & 11.86 & 3.07 + u peg & w & 2.520 & 0.375 & 1.15@xmath132 0.01 & 0.38@xmath132 0.01 & 0.72@xmath132 0.02 & 1.66@xmath132 0.05 & 0.80@xmath132 0.01 & 4.70@xmath132 0.50 & 3.84 & 7.37 & 1.50 & 11.81 & 3.05 + ao cam & w & 2.354 & 0.330 & 1.12@xmath132 0.01 & 0.49@xmath132 0.01 & 0.77@xmath132 0.02 & 1.54@xmath132 0.05 & 0.80@xmath132 0.00 & 5.56@xmath132 0.55 & 5.24 & 6.77 & 1.34 & 11.51 & 2.98 + gz and & w & 2.279 & 0.305 & 1.12@xmath132 0.02 & 0.59@xmath132 0.02 & 0.75@xmath132 0.06 & 1.68@xmath132 0.10 & 0.84@xmath132 0.01 & 4.27@xmath132 0.91 & 6.24 & 7.39 & 1.49 & 11.93 & 3.06 + tw cet & w & 2.320 & 0.317 & 1.06@xmath132 0.00 & 0.61@xmath132 0.00 & 0.68@xmath132 0.00 & 1.74@xmath132 0.00 & 0.78@xmath132 0.00 & 4.32@xmath132 0.00 & 5.74 & 7.82 & 1.63 & 12.04 & 3.11 + bv dra & w & 2.376 & 0.350 & 1.04@xmath132 0.02 & 0.43@xmath132 0.01 & 0.59@xmath132 0.02 & 1.76@xmath132 0.05 & 0.87@xmath132 0.01 & 3.72@xmath132 0.43 & 4.55 & 8.21 & 1.78 & 12.09 & 3.17 + bx peg & w & 2.016 & 0.280 & 1.02@xmath132 0.12 & 0.38@xmath132 0.05 & 0.67@xmath132 0.10 & 1.42@xmath132 0.20 & 0.69@xmath132 0.01 & 7.76@xmath132 3.46 & 7.44 & 6.55 & 1.34 & 11.02 & 2.93 + ou ser & w & 1.989 & 0.297 & 1.02@xmath132 0.01 & 0.18@xmath132 0.01 & 0.50@xmath132 0.02 & 1.73@xmath132 0.05 & 0.72@xmath132 0.01 & 4.72@xmath132 0.60 & 6.62 & 8.44 & 1.90 & 11.98 & 3.22 + ab and & w & 2.308 & 0.332 & 1.01@xmath132 0.02 & 0.49@xmath132 0.01 & 0.66@xmath132 0.06 & 1.54@xmath132 0.14 & 0.80@xmath132 0.04 & 5.53@xmath132 2.00 & 5.16 & 7.05 & 1.46 & 11.35 & 2.99 + sw lac & w & 2.380 & 0.321 & 0.98@xmath132 0.00 & 0.78@xmath132 0.00 & 0.61@xmath132 0.00 & 1.88@xmath132 0.00 & 0.86@xmath132 0.00 & 3.28@xmath132 0.00 & 5.59 & 8.62 & 1.86 & 12.51 & 3.25 + ty boo & w & 2.151 & 0.317 & 0.93@xmath132 0.02 & 0.40@xmath132 0.01 & 0.51@xmath132 0.03 & 1.66@xmath132 0.10 & 0.81@xmath132 0.03 & 4.58@xmath132 1.12 & 5.73 & 8.11 & 1.82 & 11.71 & 3.15 + vw cep & w & 1.972 & 0.278 & 0.93@xmath132 0.02 & 0.40@xmath132 0.01 & 0.57@xmath132 0.05 & 1.48@xmath132 0.11 & 0.66@xmath132 0.02 & 7.48@xmath132 2.18 & 7.56 & 7.07 & 1.52 & 11.05 & 2.98 + bw dra & w & 1.957 & 0.292 & 0.92@xmath132 0.02 & 0.26@xmath132 0.01 & 0.45@xmath132 0.01 & 1.65@xmath132 0.05 & 0.73@xmath132 0.01 & 5.23@xmath132 0.59 & 6.84 & 8.29 & 1.91 & 11.69 & 3.20 + tx cnc & w & 2.488 & 0.383 & 0.91@xmath132 0.10 & 0.50@xmath132 0.06 & 0.50@xmath132 0.08 & 1.71@xmath132 0.29 & 0.89@xmath132 0.03 & 3.90@xmath132 2.32 & 3.63 & 8.32 & 1.87 & 11.90 & 3.20 + v757 cen & w & 2.345 & 0.343 & 0.88@xmath132 0.00 & 0.59@xmath132 0.00 & 0.49@xmath132 0.00 & 1.74@xmath132 0.00 & 0.85@xmath132 0.00 & 3.94@xmath132 0.00 & 4.77 & 8.53 & 1.93 & 12.04 & 3.24 + v829 her & w & 2.273 & 0.358 & 0.86@xmath132 0.02 & 0.37@xmath132 0.01 & 0.47@xmath132 0.02 & 1.53@xmath132 0.05 & 0.74@xmath132 0.01 & 6.09@xmath132 0.77 & 4.31 & 7.68 & 1.74 & 11.21 & 3.07 + cc com & w & 1.587 & 0.221 & 0.72@xmath132 0.02 & 0.38@xmath132 0.01 & 0.35@xmath132 0.07 & 1.49@xmath132 0.11 & 0.53@xmath132 0.01 & 9.22@xmath132 2.53 & 11.52 & 8.11 & 1.97 & 11.14 & 3.18 + xy leo & w & 1.943 & 0.284 & 0.76@xmath132 0.15 & 0.46@xmath132 0.06 & 0.35@xmath132 0.26 & 1.68@xmath132 0.46 & 0.63@xmath132 0.05 & 5.75@xmath132 6.06 & 7.25 & 9.07 & 2.22 & 12.03 & 3.39 + v523 cas & w & 1.662 & 0.234 & 0.75@xmath132 0.03 & 0.38@xmath132 0.02 & 0.36@xmath132 0.07 & 1.53@xmath132 0.13 & 0.56@xmath132 0.01 & 8.06@xmath132 2.47 & 10.48 & 8.23 & 1.99 & 11.31 & 3.20 + bh cas & w & 2.373 & 0.406 & 0.74@xmath132 0.06 & 0.35@xmath132 0.03 & 0.40@xmath132 0.03 & 1.36@xmath132 0.12 & 0.69@xmath132 0.01 & 8.61@xmath132 2.46 & 3.12 & 7.23 & 1.70 & 10.56 & 3.00 + rw dor & w & 1.866 & 0.285 & 0.64@xmath132 0.00 & 0.43@xmath132 0.00 & 0.24@xmath132 0.00 & 1.63@xmath132 0.00 & 0.68@xmath132 0.00 & 5.71@xmath132 0.00 & 7.17 & 9.84 & 2.62 & 12.30 & 3.66 + rw com & w & 1.471 & 0.237 & 0.56@xmath132 0.06 & 0.20@xmath132 0.03 & 0.15@xmath132 0.01 & 1.41@xmath132 0.12 & 0.59@xmath132 0.01 & 9.49@xmath132 2.80 & 10.20 & 9.68 & 2.79 & 11.77 & 3.74 +

recently , our understanding of the origin of w uma - type contact binaries has become clearer . initial masses of their components were successfully estimated by yildiz and doan using a new method mainly based on observational properties of overluminous secondary components . in this paper , we continue to discuss the results and make computations for age and orbital evolution of these binaries . it is shown that the secondary mass , according to its luminosity , also successfully predicts the observed radius . while the current mass of the primary component is determined by initial masses , the current secondary mass is also a function of initial angular momentum . we develop methods to compute the age of a- and w - subtype w uma - type contact binaries in terms of initial masses and mass according to the luminosity of the secondaries . comparisons of our results with the mean ages from kinematic properties of these binaries and data pertaining to contact binaries in open and globular clusters , have increased our confidence on this method . the mean ages of both a- and w - subtype contact binaries are found as 4.4 and 4.6 gyr , respectively . from kinematic studies , these ages are given as 4.5 and 4.4 gyr , respectively . we also compute orbital properties of a - subtype contact binaries at the time of the first overflow . initial angular momentum of these binaries is computed by comparing them with the well - known detached binaries . the angular momentum loss rate derived in the present study for the detached phase is in very good agreement with the semi - empirical rates available in the literature . in addition to the limitations on the initial masses of w uma - type contact binaries , it is shown that the initial period of these binaries is less than about 4.45 d. [ firstpage ] binaries : close - binaries : eclipsing - stars : evolution - stars : interior - stars : late - type .

hpv or the human papillomavirus , is one of the most widespread sexually transmitted diseases [ 1 , 2 ] . over half of the sexually active women population hpv infection can transpire in women of all age consortium , also higher rates of hpv infectivity are generally perceived in women 20 - 24 years old . for the most part , genital hpv infections are asymptomatic , ephemeral , and resolve without no treatment spontaneously and cause no disorders or complaints . genital hpv is classified as high risk which mostly is related to types 16 and 18 or low risk that is related to types 6 and 11 , reflecting the potential risk to develop malignancy . the development of cervical intraepithelial neoplasia and cervical cancer is in correlation with a previous continual cervix uteri infection with a high risk hpv type . hpv types 16 and 18 are the prime cause of 70% of all cervical cancers . cervical cancer transparency worldwide indicates that it is primarily a problem of low resource countries for the main reason of limited access to screening and treatment facilities . in countries with organized screening programs , cervical cancer incidence and mortality cervical cancer is easily accessible to biopsy and also easily recognizable before development because of its long latent period , there for screening programs can be most effective , and there is an effective treatment in precursor disease . cervical cancer is the second common malignancy among women and the most frequent of gynecologic cancers worldwide . only in 2008 about 530,232 new cases were diagnosed , and 85.5% of these emerged in developing countries . in developing countries , cervical cancer is one of the chief public health issues and the leading cause of deaths related to cancer among women . cervical cancer 's crude incidence rate in iran is 6 - 8 per 100,000 . it has been hoped that the on hand hpv vaccines will noticeably diminish the burden of cervical cancer and also other hpv - related diseases in developing countries . the hpv vaccine provides a chance to considerably decrease the transmission of both high risk types 16 , 18 and low risk types 6 , 11 and by doing so , not only reduce cervical cancer incidence and mortality rate , but also the financial burden of diagnosis and treatment interventions . infections can be prevented for those with no prior exposure , there for administration have to take place in adolescents and before their sexual debut . the vaccine is expensive and not available to the public in low income countries [ 10 - 12 ] . numerous studies , mainly in developed countries , have revealed that both health care providers and the general public have various knowledge of hpv infection and vaccines [ 13 - 21 ] . nurses as a group of health care professionals can have important role in immunization programs , they because of their social situation can provide health education to the public and their knowledge of hpv infection and vaccine prevention will influence on the success of the immunization program against cervical cancer . based on our knowledge up to know there is no study on attitude and knowledge of health care professionals about hpv and its vaccination in iran . this study evaluated the knowledge of hpv infection and vaccines and tried to determine the attitude and approach toward these vaccines among the female nurses at shahid sadoughi university of medical sciences , yazd , iran . this cross sectional descriptive study conducted among the nursing staff of shahid sdoughi teaching hospital , yazd , iran . the study is approved by research ethics committee of shahid sadoughi university of medical sciences , yazd , iran . assuming that 50% of the female nurses had sufficient knowledge of genital hpv infection , and with 95% confidence and 5% reliability about 300 needed participants were calculated for the study . the instrument of data collection was questionnaire covered information on socio demographic traits , on alertness and knowledge of hpv infections , cervical cancer , and hpv vaccines , and on approval of these vaccines . the questionnaire was developed in consultation with a health educator , two midwives , one gynecologist and an expert in questionnaire validation and its validity was confirmed . also internal consistency of questionnaire was confirmed by piloting and calculating related ( = 0.79 ) . the purpose of the study was explicated to all nurses and their verbal consent was obtained before they were handed a pretested , structured , anonymous , self - administer questionnaire . all registered information was transferred into spss-15 software using -test or fisher 's exact tests . out of the three hundred and eighty questionnaires that were disseminated , 357 female nurses completed and sent back their questionnaires . two hundred and eighty one ( 78.7% ) of the respondents were married while 76 ( 21.3% ) were single . about 64 ( 17.9% ) respondents were working in midwifery section and 293(82.1% ) in other sections . only one hundred and thirty - one of the nurses ( 36.7% ) knew about hpv infection and how it can cause abnormal pap smear results . about 130 ( 36.5% ) of them were aware that it is possible for the infected person to have no sign or symptoms . and only 37 ( 10.4% ) of the nurses knew hpv may not cause herpetic lesions in men and women ( tab . about 208(58.3% ) of the nurses knew that hpv could be transmitted by sexual intercourse , while only 40 ( 11.2% ) were aware that it could be passed on by skin - to - skin contact . 147 ( 41.2% ) of the nurses affirmed they would be inclined to be vaccinated , whereas 210 ( 58.8% ) were reluctant to vaccination ; reason given for unwillingness by 26.2% was inadequate knowledge of the hpv vaccines and 41.4% were concerned about the complication of the vaccine ( tab . questions about vaccine of hpv and responses of participants about hpv infection and its relation to cancer . about 146 ( 40.9% ) of respondents supported vaccination of preadolescent girls , while 209 ( 59.1% ) did not . the ground on which to not advocate the hpv vaccination for preadolescent girls included ( 1 ) safety of the vaccine is not unverified ; ( 2 ) the vaccine is expensive ; and ( 3 ) the lack of enough knowledge about the vaccines and its potential complications . only 16 ( 4.5% ) of the respondents knew that vaccination of hpv can prevent cervix cancer and 20 ( 5.6% ) knew that vaccination of hpv can prevent genital warts . out of the three hundred and eighty questionnaires that were disseminated , 357 female nurses completed and sent back their questionnaires . two hundred and eighty one ( 78.7% ) of the respondents were married while 76 ( 21.3% ) were single . about 64 ( 17.9% ) respondents were working in midwifery section and 293(82.1% ) in other sections . only one hundred and thirty - one of the nurses ( 36.7% ) knew about hpv infection and how it can cause abnormal pap smear results . about 130 ( 36.5% ) of them were aware that it is possible for the infected person to have no sign or symptoms . and only 37 ( 10.4% ) of the nurses knew hpv may not cause herpetic lesions in men and women ( tab . about 208(58.3% ) of the nurses knew that hpv could be transmitted by sexual intercourse , while only 40 ( 11.2% ) were aware that it could be passed on by skin - to - skin contact . 147 ( 41.2% ) of the nurses affirmed they would be inclined to be vaccinated , whereas 210 ( 58.8% ) were reluctant to vaccination ; reason given for unwillingness by 26.2% was inadequate knowledge of the hpv vaccines and 41.4% were concerned about the complication of the vaccine ( tab . questions about vaccine of hpv and responses of participants about hpv infection and its relation to cancer . about 146 ( 40.9% ) of respondents supported vaccination of preadolescent girls , while 209 ( 59.1% ) did not . the ground on which to not advocate the hpv vaccination for preadolescent girls included ( 1 ) safety of the vaccine is not unverified ; ( 2 ) the vaccine is expensive ; and ( 3 ) the lack of enough knowledge about the vaccines and its potential complications . only 16 ( 4.5% ) of the respondents knew that vaccination of hpv can prevent cervix cancer and 20 ( 5.6% ) knew that vaccination of hpv can prevent genital warts . awareness of hpv infection and vaccines was moderately low amongst nurses in this study . despite the understanding and familiarity of cervical cancer and hpv infection , a relatively low proportion ( 36.7% ) knew about the correlation between hpv infection and cervical cancer . in other parallel studies 78.5% of greek , 71% of new zealander , and 81.8% thai nurses were aware of this correlation [ 21 - 24 ] . this data exhibits the inadequate knowledge of nurses in our study and the necessity of increasing this knowledge . a number of studies display that knowledge of hpv infection is higher in countries with an existing nationwide hpv education programs . these programs caused an enhanced alertness and better knowledge and understanding of hpv infection and associated diseases among health care providers and the general public . in this iranian study , only a 16 ( 4.5% ) of the nurses knew they were for the prevention of cervical cancer . the nominal familiarity of the hpv vaccine among the nurses in this iranian study may be due to the lack of education programs about cervical cancer and hpv infection in iran . the important notable issue is that our participants we nurses and reasonably they passed some lessons about viral infections and malignancies . in fact our participants were previously educated during their graduation courses but even in such group of people we found lack of knowledge . this shows needs for continues educational programs for all target groups as most of our previously educated respondents were failed to answer knowledge questions of our study . these results are lower than those obtained from nurses in the thai and nigerian studies [ 24 , 25 ] . 146 ( 40.9% ) of the nurses these findings were lower than what was stated in other recent studies [ 13 , 14 , 19 , 21 , 25 , 26 ] . these studies initiated that despite the overall lack of knowledge about hpv infection and other related diseases , the public interest in the hpv vaccination was significant . studies also display that the main predictors of providers ' intent to recommend hpv vaccination are endorsed by specialized organizations and provider of knowledge and approach toward hpv vaccination [ 23 , 26 , 27 ] . furthermore , the authors point out that the nurses who gave their consent to be vaccinated were also the more likely to suggest the vaccine for preadolescent girls . the nurses ` justification for not consenting to the hpv vaccines or promoting it for preadolescent girls was the information inadequacy about the effectiveness and safety of the vaccines and also the high cost of the vaccine . in other studies , these factors were also acknowledged as difficulties to an effectual hpv immunization [ 14 , 28 - 30 ] . virtually all the nurses sought to obtain more information about the vaccines . the results of this study confirm the lack of nurses ` knowledge about hpv vaccine and its relation to cervical cancer and also the ways of this cancer prevention . considering with this fact that nurses are educated previously during graduation courses and their low level of knowledge about hpv infection and vaccine , we recommend contentious educational programs for health care staffs as they are one of the most sources of public to get information about diseases . our study shows an urgent need to design similar studies in other regions of iran and draw a broad estimation on knowledge of different target groups to make a national program to increase the knowledge of women on this matter and help to decrease the rate of cervical cancer in iranian population . the relatively small sample size and it being as self - administer , are the probable confines of this study . the relatively small sample size and it being as self - administer , are the probable confines of this study .

summarybackground and aim.human papilomavirus ( hpv ) is one of the most widespread sexually transmitted diseases is highly related to cervical cancer in women . cervical cancer 's crude incidence rate in iran is 6 - 8 per 100,000 . the hpv vaccine provides a chance to considerably decrease the transmission of most types of hpv . the aim of this study was to evaluate awareness and knowledge of hpv infection and vaccines and to assess the attitude and approach toward these vaccines among female nurses at shahid sadoughi university of medical sciences , yazd , iran.materials and methods.this cross - sectional , descriptive study was performed among 380 female nurses . data were collected using a questionnaire was consisted in demographic variables and questions on knowledge of participants about hpv infection , hpv vaccine and cervical cancer and also questions on attitude of nurses towards hpv vaccination . the validity and internal consistency of questionnaire was confirmed during experts consents and pilot testing ( = 0.79 ) . data analysis was performed using spss15 using 2-test or fisher 's exact test.results.three hundred and eighty questionnaires were distributed and 357 female nurses completed and returned their questionnaires : only one hundred and thirty - one of the nurses ( 36.7% ) knew about hpv infection and how it can cause abnormal pap smear results . about 147 ( 41.2% ) of the nurses stated they would want to be vaccinated . about 146 ( 40.9% ) of respondents supported vaccination of preadolescent girls.conclusion.the results of this study confirm the lack of knowledge about hpv vaccine and its relation to cervical cancer and also the ways of this cancer prevention . our study shows an urgent need to design similar studies in other regions of iran and draw a broad estimation on knowledge of different target groups to make a national program to increase the knowledge of women on this matter and help to decrease the rate of cervical cancer in iranian population .

we study the photosynthetic apparatus of the purple bacterium _ rhodobacter sphaeroides _ , which consists of reaction centers surrounded by two types of transmembrane antenna complexes , lh1 and lh2 @xcite . although all complexes can absorb light directly , the dominant energy - transfer pathway is lh2 @xmath0 lh1 @xmath0 rc . the complexes can arrange themselves in many ways @xcite ; as a representative example we consider an array of ten evenly spaced lh2s surrounding the core lh1-rc complex , as shown in fig . [ fig : structure ] . the coordinates of the pigments in fig . [ fig : structure ] are taken from the available crystal structures @xcite . each lh1 complex consists of 56 bacteriochlorophyll _ a _ molecules ( bchl ) with an average nearest - neighbor mg mg distance of and immediately encircling two rcs @xcite . these bchls absorb at and are thus referred to as the b875 aggregate . each rc comprizes four bchls , two in the tightly - coupled special pair and two accessory ones . the absorption spectrum of the rc has peaks at and , corresponding to the special pair and the accessory bchls , respectively . lh2 complexes surrounding the lh1-rc core include two rings each , one with 9 bchls ( the b800 subunit ) and the other 18 ( b850 ) @xcite . we only consider the b850 ring because b800 excitons are transferred to b850 efficiently and quickly ( @xcite ) and efficiently using supertransfer @xcite , making their ultimate fate nearly identical to that of excitons starting at b850 . the average distance between bchls in b850 is . the distances between complexes have been determined by atomic force microscopy ( afm ) @xcite , and our model uses the most common center - to - center spacing between lh2s , . this gives a distance of between nearest mg atoms in different lh2s , which we also used to set the separation between the lh2s and lh1 . we refer to the geometry just described as the natural geometry ( n ) , to distinguish it from the trimmed geometry ( t ) ( fig . [ fig : rates]b ) , in which every other bchl was removed to reduce nearest - neighbor couplings and encourage exciton localization ( see below ) . for example , the distance between bchls in b850 roughly doubles upon trimming , becoming comparable to that in the b800 ring , where delocalization is known to be minor . to trim each rc , out of the four bchls , we kept one of the special pair and the less - strongly coupled accessory bchl . we also considered cases where only some of the complexes ( lh2 , lh1 , and/or rc ) were trimmed . the extent of the trimming ( keeping every second bchl ) is not critical to our argument : supplementary table 4 shows similar results if only every third bchl is kept . strong coupling between neighboring bchls in the natural geometry leads to exciton delocalization @xcite . within each complex ( lh2 , lh1 , or rc ) , the excitonic states are the eigenstates of a frenkel hamiltonian @xcite that , in the weak - light , single - exciton regime , reads @xmath1 where @xmath2 are the site states , @xmath3 are the site energies , and @xmath4 are the couplings . the site energies and couplings have been calculated by numerous groups @xcite , with the final values varying widely due to different electronic - structure methods and assumptions about the molecular environment . for instance , values between @xmath5 and @xmath6 have been used for the coupling between the @xmath7 and @xmath8 bchls in lh2 @xcite . to confirm that our conclusions are general and not sensitive to the details of the models , we carried out the entire study using two sets of simulation parameters , which we call @xmath9 and @xmath10 because they are inspired by the approaches taken in schulten s and renger s groups ( table [ parameters ] ) . some differences between the two approaches are worth noting . schulten obtains nearest - neighbor couplings from electronic - structure theory ( table [ parameters ] ) and more distant ones using the point - dipole approximation ( pda ) @xcite . although the pda is accurate at large separations , it can fail even at moderate separations of tens of angstroms , enough to encompass many non - nearest - neighbors @xcite . by contrast , renger s tresp method @xcite reproduces quantum - chemical couplings with an accuracy better than the unavoidable errors in almost all cases @xcite , which is why we use it for all couplings in @xmath10 , except for the special pair , which is too close for tresp @xcite . .site energies and couplings . abbreviations : @xmath11 and @xmath12 : alternating bchls in the b850 unit of lh2 ; p@xmath13 , p@xmath14 : special pair bchls in rc ; b@xmath13 , b@xmath14 : accessory bchls in rc . [ cols= " < , < , < , < , < " , ] the largest differences between @xmath9 and @xmath10 are in the relative permittivity @xmath15 and the transition dipole moment @xmath16 of each bchl , both of which enter coupling calculations ( whether pda or tresp ) through the ratio @xmath17 . schulten sets @xmath18 so that the pda reproduces the quantum - chemical coupling ( in vacuum ) between a particular pair of bchls @xcite . this can lead to errors because the long - range couplings now depend on the quantum - chemical method used for the short - range coupling between the calibration pair , as well as on the choice of that pair . consequently , published values of @xmath18 have included @xcite , @xcite , @xcite , @xcite , and @xmath19 @xcite . we use @xmath20 and @xmath21 , corresponding to @xmath22 @xcite , while noting the unrealistically large dipole moment . renger has argued that coupling calculations should use the measured value of @xmath16 @xcite , estimated at in vacuum and in a medium with @xmath20 ( the effective permittivity of protein complexes @xcite ) @xcite . calculations with molecules in cavities surrounded by the dielectric lead to an effective @xmath15 from 1.25 to 1.67 @xcite . the recommended combination of @xmath23 and @xmath24 @xcite corresponds to @xmath25 . ( alternatively , forgoing the cavity model and using @xmath20 and @xmath26 gives a similar value , @xmath27 . ) the large discrepancy between @xmath9 and @xmath10 on the value of @xmath18 has a substantial influence on inter - complex fret rates , which are proportional to @xmath28 . for the @xmath9 parameter set , site energies are taken from schulten s papers ( see table [ parameters ] ) , and @xmath10 energies are chosen so that the brightest states of each complex is aligned with the absorption maximum . we neglect disorder in site energies , because its effect on the inter - complex transfer rates is small ( about 20% for lh2@xmath0lh2 @xcite ) compared to that caused by differences between @xmath9 and @xmath10 parameters . the resulting difference in the efficiency would be even less , as is the case for the cyanobacterial photosystem i , where disorder changes the efficiency by about 1% @xcite . the two geometries natural and trimmed differ in the inter - pigment couplings , which affects the excitonic states . in the t geometry , we assume that the coupling between the pigments is much weaker than the coupling of the pigments and their environment . in that case , excitons can be thought of as localized on individual sites , and eet is described using frster s theory of resonant energy transfer ( fret ) @xcite . by contrast , in the n geometry , we assume that the inter - pigment coupling is much stronger than the pigment - bath coupling , leading to delocalized excitons being the better theoretical description . for every aggregate ( i.e. , each lh2 , lh1 , and rc ) , we construct the excitonic states @xmath29the eigenstates of that aggregate s hamiltonian ( eq . [ eq : h])with dynamics described using redfield theory @xcite . the two approaches full localization and full delocalization are two ends of a spectrum . the reality partially localized eigenstates , depending on the details of the system - bath interaction is somewhere in between . nevertheless , we focus on these two extremes because they serve to isolate the effect of delocalization on efficiency , which would persist in a diminished form even if the delocalization were only partial . in all cases , the coupling between different aggregates is weak and is described by fret . however , delocalization within the aggregates can affect the inter - aggregate fret rate , potentially leading to supertransfer @xcite , an effect proposed to be important for the efficiency of purple - bacterial light harvesting @xcite . for example , if the donor contains two pigments and the exciton is localized on either with probability @xmath30 , each pigment contributes equally to the total eet rate to the acceptor , @xmath31 . but if the exciton is delocalized over the donor sites , the effective transition dipole of the donor is a linear combination of molecular transition dipoles . in the best case , with the exciton in the bright state @xmath32 , the transfer rate is doubled , @xmath33 if @xmath34 . the approximation that the overall transition dipole of the donor eigenstate couples to the acceptor is only valid at large separations . otherwise , the acceptor sees individual donor sites and not simply a super - molecule , a situation correctly described using generalized fret ( gfret ) @xcite , which gives the coupling between a donor state @xmath35 and an acceptor state @xmath36 as @xmath37 where @xmath38 ( @xmath39 ) are the site - basis coefficients of the exciton states of the donor ( acceptor ) and @xmath4 is the coupling between site @xmath40 of the donor and site @xmath41 of the acceptor . to distinguish ordinary , site - to - site fret used in the t geometry from the gfret in the n geometry , we refer to the former as ofret . once the coupling is known , the fret rate is @xcite @xmath42 where the indices @xmath43 ( donor ) and @xmath44 ( acceptor ) refer to either sites @xmath40 and @xmath41 in ofret or eigenstates @xmath35 and @xmath36 in gfret . @xmath45 is the overlap between the normalized fluorescence spectrum @xmath46 of @xmath43 and the normalized absorption spectrum @xmath47 of @xmath44 . the spectra @xmath46 and @xmath47 can be calculated using multichromophoric fret theory , given a detailed model of each pigment s environment @xcite . for example , a gfret calculation of the lh2@xmath0lh2 transfer rate using an ohmic spectral density @xcite agrees with the same calculation with the exact heom method @xcite . however , transfer rates are sensitive to changes in the spectral density , meaning that substantial errors are introduced by the simplistic assumption of an ohmic spectral density . because we doubt that currently available spectral densities are accurate enough to justify computing @xmath46 and @xmath47 , we parametrize @xmath48 using experimental data . we make the simplest possible choice , taking both @xmath49 and @xmath50 to be normalized gaussian functions centered at @xmath51 , with the standard deviation @xmath52 chosen to reproduce the width of the q@xmath53 band of bchl__a _ _ in solution @xcite . with gaussian spectra , @xmath48 becomes @xmath54 where @xmath55 is the energy difference . neglecting the stokes shift between @xmath46 and @xmath56 would imply @xmath57 , causing eq . [ eq : fretrate ] to break detailed balance . we correct this by using eq . [ eq : fretrate ] only for energetically downward transitions ( @xmath58 ) , otherwise taking @xmath59 , where @xmath60 is the ambient temperature . transfer rates obtained using this approach agree with those obtained by schulten s group . for lh2@xmath0lh2 transfer , with the center - to - center distance increased to , we obtain a transfer time of , close to the obtained by schulten s group using gfret with their chosen ohmic spectral density @xcite . a complete model of eet also includes exciton loss ( recombination ) and creation by optical pumping . excitons can recombine radiatively or non - radiatively . we incorporate radiative relaxation of site / exciton @xmath43 by adding the rate of spontaneous emission @xmath61 , where @xmath62 is the radiative decay rate of bchl in solution @xcite , @xmath63 is the ratio of the oscillator strength of the transition to that of the single bchl , and @xmath64 is the ( small ) correction to spontaneous emission as the energy of the transition changes with respect to the transition energy of bchl in solution , @xmath65 . we include a non - radiative recombination rate of @xmath66 for all @xmath43 @xcite . in the natural geometry there is also intra - aggregate relaxation ( internal conversion ) among the excitonic states , occurring on a sub - picosecond timescale @xcite . we incorporate it by assuming , within each aggregate ( lh2 , lh1 , or rc ) , internal conversion from higher - energy states to lower ones at a rate @xmath67 , while the energetically uphill rates are included by detailed balance . the speed of internal conversion relative to other processes means that each aggregate will be close to a boltzmann state , as was confirmed for lh2 @xcite . in natural light , the incoherent light populates system eigenstates and not their superpositions @xcite , giving rise to a steady state @xcite . in principle , these are vibronic eigenstates of the entire light - harvesting apparatus , which raises two considerations . first , eigenstates of the entire apparatus will include superpositions of different complexes . however , inter - complex delocalization is often neglected because it is destroyed by dynamic localization faster than other relevant timescales . this is especially true when the complexes are not energetically resonant and when the system - bath coupling is stronger than the inter - complex coupling , both conditions that apply here . furthermore , although inter - complex delocalization may increase the absorption of the rc somewhat @xcite , that would modify the efficiency only slightly because most light is absorbed by the antenna complexes and not the rc . second , the steady - state density matrix of each complex may not be diagonal in the electronic basis due to the system - bath coupling @xcite . however , our intra - complex redfield treatment assumes weak system - bath coupling , meaning that off - diagonal elements will be small . we therefore neglect this correction because its influence is likely to be smaller than , say , the difference between @xmath9 and @xmath10 parameters . therefore , we assume that incoherent light populates the sites in the t geometry and the excitonic states of individual aggregates in the n geometry . for site / exciton @xmath43 , the optical pumping rate is @xmath68 , where @xmath69 is the mean photon number at that energy and @xmath70 is the effective black - body temperature of solar radiation . the final ingredient is the assumption that excitons in the rc can drive charge separation , at a rate @xmath71 @xcite . with all the rates described above , and because there are no coherences in incoherent sunlight , the dynamics of the system can be described using a pauli master equation , @xmath72 where @xmath73 is the vector containing the populations @xmath74 of all the sites ( t geometry ) or excitonic states ( n geometry ) , along with the population @xmath75 of the ground state , while the rate matrix @xmath76 includes all the rates listed above ( and summarized in fig . [ fig : rates]c d ) , @xmath77 we define the efficiency as the quantum yield of charge separation , i.e. , the probability that a photon absorbed by any of the complexes eventually drives charge separation in the rc . because energy can be lost along the way , this is not a thermodynamic efficiency . because incoherent excitation is stationary , the molecular ensemble will be at steady state , @xmath78 @xcite . since @xmath79 , @xmath78 can be easily found as the unique eigenvector of @xmath76 with eigenvalue zero . the efficiency is then the rate of charge separation in the rc divided by the rate at which excitons are created , @xmath80 where @xmath81 is the steady - state population of the ground state . the @xmath82 in the denominator ensures @xmath83 is intensity - independent as long as the light is weak and @xmath84 . [ eq : efficiency ] can be compared to the efficiency used by schulten s group , @xmath85 , where @xmath86 is a uniform distribution over the rc sites and @xmath87 is the initial distribution @xcite . this definition is not conceptually suited to steady - state light harvesting , where there is no `` initial '' state , although the two approaches are equivalent if a suitable `` initial '' state is chosen @xcite . because the initial state can influence the efficiency substantially @xcite , it is important to model the light absorption and not assume an initially localized state @xcite or a uniform distribution over many @xcite . the overall efficiencies of the various cases are summarized in fig . [ fig : barchart ] , with details , including inter - complex transfer rates , in supplementary table 1 . the results obtained using the @xmath9 and @xmath10 parameters can be quite different due to the weaker long - range coupling in @xmath10 , confirming our concern about the difficulty of precise calculations and the need to focus on general trends . figure [ fig : barchart ] shows that delocalization is not necessary for high efficiency . in particular , in the @xmath9 parameters ( but not @xmath10see below ) the trimmed geometry ttt is as efficient as the natural geometry nnn . in addition , delocalization in lh2 always diminishes the efficiency : with both @xmath9 and @xmath10 parameters , @xmath88 for all @xmath89 , disproving the hypothesis that delocalization in lh2 benefits the efficiency through supertransfer . by contrast , delocalization in the rc is always beneficial , while in lh1 delocalization benefits the efficiency if and only if there is delocalization in the rc . whether delocalization is beneficial or deleterious can be explained using eq . [ eq : fretrate ] . delocalization affects the eet rate by altering both @xmath90 ( potentially yielding supertransfer ) and the excitonic energy gaps ( through the davydov splittings ) . indeed , the spectral overlap is exponentially sensitive to excitonic splittings ( eq . [ eq : overlap ] ) , unlike supertransfer , which is at best an improvement by a constant factor equal to the number of sites . delocalization in lh2 is deleterious because it weakens the energy funnel into lh1 . lh2 sites are higher in energy than lh1 sites , ensuring that backward transfer lh1@xmath0lh2 is suppressed . if the excitons are delocalized , the bright state of lh2 is lowered in energy by the davydov splitting , bringing it closer to lh1 . although this encourages forward transfer , it increases backward transfer even more because of detailed balance . furthermore , because there are 10 lh2s and only one lh1 , there are 10 times as many pathways back to lh2 . consequently , the highest efficiencies occur when the forward rate is much greater than the backward rate ( see supplementary table 1 ) . in particular , the main pathway between lh2 and lh1 is through their brightest eigenstates , which have a gap of about @xmath91 . if lh2 is trimmed , eet occurs through the sites , whose energy is about @xmath92 above the brightest state of lh1 . the increased gap makes backward eet exceedingly slow , while keeping the forward rate adequate for high efficiency . the analysis in the rc is analogous . its site energies are higher than in lh1 , which would inhibit efficient transport . including the excitonic couplings splits the levels , brining the lower one closer to lh1 in energy and increasing the rate of forward eet @xcite . the efficiency is worst when lh1 is delocalized and rc is not ( nnt and tnt ) , because that maximizes the energy difference between lh1 and the rc . of course , the spectral overlap does not offer the complete explanation . although the smallest energy gap between lh1 and rc occurs when both complexes are trimmed , the highest lh1@xmath0rc rate is when both are delocalized . this is due both to the brightness of the exciton states in both complexes ( supertransfer ) and the larger number of pathways toward the rc when there are four bchls as opposed to two . the importance of the number of pathways ( i.e. , entropic driving ) is further illustrated in supplementary table 3 . the preceding discussion suggests that excitonic couplings affect eet rates more through energy - level shifts than through supertransfer . if so , the poor performance in cases such as nnt and tnt should be correctable by adjusting the site energies . we tested this hypothesis by repeating the simulations with site energies as free parameters . bchl site energies vary widely in photosynthetic complexes : single substitutions on the protein backbone can significantly affect the energy , especially if the residue axially ligates the magnesium or if is charged and thus modifies the electrostatic environment @xcite . it is therefore plausible that natural selection could have modified the site energies ( within limits , of course ) if it increased fitness . as fig . [ fig : barchart ] shows , choosing the optimal value for the site energies of lh1 and lh2 ( relative to the average special - pair energy @xmath93 ) dramatically enhances the efficiency in all cases . in the @xmath9 parameters , the optimized efficiency is always above @xmath94 . the @xmath10 parameters do not perform as well due to weaker long - range couplings , but the optimal efficiency is nevertheless always above @xmath95 , i.e. , the same or greater than the natural - case efficiency of @xmath95 . for details , see supplementary table 2 . the behaviour of the efficiency with changes in the site energies @xmath96 and @xmath97 is shown in fig . [ fig : optimisation ] . most features of the plots can be understood as consequences of energy funnelling . for example , the efficiency is negligible unless lh1 is higher in energy than the rc or only slightly ( a few @xmath98 ) lower , but not so high that their spectra no longer overlap . when lh2 is also considered , there are four regions of interest , labeled a d in fig . [ fig : optimisation ] , depending on the offset @xmath99 . the peak b occurs when there is a clear energy funnel toward lh1 , whereas in the adjacent valley c , lh2 is slightly lower than lh1 , so that outward transfer lh1@xmath0lh2 dominates . this problem is compounded by the number of available pathways ( i.e. , entropy ) : because there are 10 lh2s in the model , an exciton on lh1 can move to an lh2 in 10 different ways ( at the same rate ) , while an exciton on lh2 has only one pathway to lh1 . therefore , the excitons accumulate in the lh2s , making the transfer to the rc unlikely . when the offset @xmath99 is large , whether positive ( a ) or negative ( d ) , the small spectral overlap between lh1 and lh2 gives a small efficiency . in those cases , only excitons starting out in lh1 or the rc contribute to the efficiency , while those from lh2by far the largest proportion cannot leave and are wasted . the efficiency in region a is higher than in region d ( and increases further in the unphysical limit @xmath100 ) because there are fewer photons at higher energies , meaning that fewer excitons start out at lh2 and are wasted . the plots for the three cases in fig . [ fig : optimisation ] ( and for all the cases that are not shown ) are qualitatively the same , differing only in the positions of the peaks and their widths . the differences in peak positions are caused by the excitonic splittings , while the different widths occur because the couplings allow both lower- and higher - energy excitonic states to act as eet donors and acceptors . delocalization in lh2 prompted speculation that it plays a functional role , having been selected by evolution because it enhanced light - harvesting efficiency . however , this is not so , since trimming the lh2 always increases the efficiency . why then is there delocalization ? the main evolutionary pressure is probably not on efficiency but on the total number of excitons processed by each rc . although removing half the bchls might increase the efficiency marginally , it would also halve the absorption cross - section of lh2 , decreasing the total exciton flux into the rc . in other words , delocalization in lh2 is a spandrel @xcite , a byproduct of packing bchls densely to maximize absorption , just as the red color of vertebrate blood is not adaptive , but a byproduct of the oxygen - carrying ability of haemoglobin , which happens to be red . indeed , a clade of cryptophyte algae underwent a mutation that reduced excitonic delocalization in their antennas @xcite with no apparent decrease in fitness . by contrast , the n geometry in the rc always outperforms t because the davydov splitting brings its energy closer to that of lh1 . however , it would put the cart before the horse to conclude that rc energy splittings are an adaptation to create better energy alignment with lh1 . rather , a strongly coupled special pair is a feature conserved across photosynthetic organisms @xcite , meaning that it arose before the advent of purple bacteria . instead , we should ask whether purple bacteria built the antennas around the rc so as to create an effective energy funnel . the answer is yes , as confirmed by the high efficiency in the natural case . even so , the alignment is not optimal , and fig . [ fig : barchart ] indicates a substantial further increase in efficiency is possible in principle , depending on how much further the site energies could realistically be altered . nevertheless , the continued survival of the species indicates that the efficiency is probably good enough that an additional increase would not confer a decisive evolutionary advantage . in particular , having the rc higher in energy than lh1 creates a rate - limiting uphill step at the end of the eet chain . it has been proposed that the uphill transfer is also adaptive , preventing too many excitons arriving at a ` closed ' rc ( one having recently undergone charge separation ) , thus averting excessive energy dissipation and thermal damage @xcite . however , we doubt that the exciton flux would be large enough to damage the rc , considering that the light - harvesting processes are completed orders of magnitude faster than the mean time between the arrivals of two photons . therefore , it appears that the final uphill step is , like delocalization , an evolutionary relic in a light - harvesting system that functions well enough , but not optimally . eet efficiency in purple bacteria can be largely understood in terms of the energy landscape , with supertransfer playing a minor role . because fret rates are exponentially sensitive to energy offsets , small changes in site energies well within the range found in nature can often improve the rates more than the maximal effect of supertransfer . despite this sensitivity , the purple - bacterial energy funnel is robust , and would yield high efficiencies across a considerable range of site energies . the dominance of energy funnelling is seen using two very different parameter sets , confirming that it is a sturdy conclusion insensitive to the details of the model . we thank vahid karimipour , elise kenny , and saleh rahimi - keshari for valuable discussions . we were supported by the australian research council through a discovery early career researcher award ( de140100433 ) and the centres of excellence for engineered quantum systems ( ce110001013 ) and quantum computation and communication technology ( ce110001027 ) . ifxundefined [ 1 ] ifx#1 ifnum [ 1 ] # 1firstoftwo secondoftwo ifx [ 1 ] # 1firstoftwo secondoftwo `` `` # 1''''@noop [ 0]secondoftwosanitize@url [ 0 ] + 12$12 & 12#1212_12%12@startlink[1]@endlink[0]@bib@innerbibempty @noop _ _ , ed . 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photosynthetic complexes improve the transfer of excitation energy from peripheral antennas to reaction centers in several ways . in particular , a downward energy funnel can direct excitons in the right direction , while coherent excitonic delocalization can enhance transfer rates through the cooperative phenomenon of supertransfer . however , isolating the role of purely coherent effects is difficult because any change to the delocalization also changes the energy landscape . here , we show that the relative importance of the two processes can be determined by comparing the natural light - harvesting apparatus with counterfactual models in which the delocalization and the energy landscape are altered . applied to the example of purple bacteria , our approach shows that although supertransfer does enhance the rates somewhat , the energetic funnelling plays the decisive role . because delocalization has a minor role ( and is sometimes detrimental ) , it is most likely not adaptive , being a side - effect of the dense chlorophyll packing that evolved to increase light absorption per reaction center . photosynthetic organisms harvest light using antenna complexes containing many chlorophyll molecules @xcite . the energy collected by the antennas is then transmitted , through excitonic energy transfer ( eet ) @xcite , to a reaction center ( rc ) , where it drives the first chemical reactions of photosynthesis . the thorough study of eet in photosynthetic antennas has been motivated , in part , by the prospect of learning how to design more efficient artificial light - harvesting devices @xcite . it has long been recognized that excitons in many photosynthetic complexes are directed toward the rc energetically : if the antennas lie higher in energy than the rc , the excitons can spontaneously funnel to the rc . a more recent discovery is that coherent mechanisms can also enhance light - harvesting efficiency . in particular , excitonic eigenstates may be localized or delocalized over a number of molecules , depending on the strength of their couplings @xcite . delocalization i.e . , coherence in the site basis makes the aggregate behave differently than a single chlorophyll molecule , and phenomena such as superradiance @xcite , superabsorption @xcite , and supertransfer @xcite can occur in densely packed aggregates . specifically , supertransfer occurs when delocalization in the donor and/or the acceptor enhances the rate of the ( incoherent ) eet between them . the presence of both funnelling and supertransfer suggests that their contributions to the efficiency could be quantified . however , the two effects are too closely related for such a separation to be easily carried out ; in particular , a change to the extent of delocalization requires changing excitonic couplings , which also determine the energy landscape . in other words , because delocalization and the energy landscape are intimately connected , it is not sufficient to alter one property to see what happens to the efficiency , because doing so also alters the other property as well . here , we show that the roles of the two processes can be separated by constructing counterfactual light - harvesting complexes that reflect plausible evolutionary alternatives . in particular , screening thousands of complexes with varying energetic landscapes and extents of delocalization allows the effects of changing one property to be examined while keeping the other as constant as possible . we describe this approach through its application to the strikingly symmetric antenna complexes of purple bacteria @xcite , which feature tightly packed bacteriochlorophylls and considerable excitonic delocalization @xcite . this delocalization is known to give rise to supertransfer , in particular for eet within the lh2 complex @xcite . in principle , supertransfer between different complexes should also occur , and although it has not been studied as well as intra - complex supertransfer , it has been proposed to explain the high light - harvesting efficiency @xcite . we show that although supertransfer is present in purple bacteria , it is not essential for efficient light harvesting . for example , eet efficiency can remain roughly as high even if half of the pigments are removed , weakening the couplings and localizing the states . when delocalization is removed from only some of the complexes , the efficiency can change drastically , but these changes are almost entirely due to shifts in energy levels ; even in the worst cases , modest modifications of the site energies can restore the high efficiency . indeed , in the presence of a strong funnel , the efficiency can be high regardless of delocalization . this suggests that the evolutionary advantage of densely packed chlorophylls is that they enhance the absorption cross - section per rc , while the delocalization is merely a side - effect of the dense packing . in evolutionary language , delocalization is a spandrel , not an adaptation @xcite .

quantum computing is a paradigm in which quantum entanglement and interference are exploited for information processing . algorithms have been proposed which can even be exponentially more effective than the best known classical solutions @xcite . elements of quantum computing have been demonstrated experimentally using nuclear magnetic resonance @xcite and trapped ions @xcite . however building systems with many coupled qubits remains a challenge . many demands must be met : reliable qubit storage , preparation and measurement , gate operations with high fidelities and low failure rate , scalability and accurate transportation or teleportation of states . the biggest problem is posed by decoherence which tends to destroy the desired quantum behaviour . in recent years much has been done to address the problems posed by decoherence . an important step was the realisation that many systems possess a large subspace of decoherence - free states @xcite which is well protected from the environment and provides ideal qubits . a great variety of approaches in manipulating the qubits within the decoherence - free subspace has been discussed in the literature . the optimal approach would be to employ only hamiltonians leaving the decoherence - free subspace invariant and therefore not causing transitions into unwanted states @xcite . however they are in general hard to identify in physical systems . alternatively , environment - induced measurements and the quantum zeno effect @xcite can be used to avoid decoherence . the idea of _ quantum computing using dissipation _ @xcite employs the fact that the presence of spontaneous decay rates can indeed have the same effect as rapidly repeated measurements , whether the system is in a decoherence - free state or not , thus restricting the time evolution onto the decoherence - free subspace . as in linear optics quantum computing @xcite , the presence of measurements has the advantage that local operations on the qubits become sufficient for the implementation of universal quantum computation . this allows significant reduction in the experimental effort for the realisation of gate operations . for example , universal quantum gates between atomic qubits can be realised with the help of a single laser pulse @xcite . however , obtaining these advantages does not always require the presence of spontaneous decay rates in the system . in some cases , the presence of a strong interaction alone is sufficient to restrict the time evolution of a system onto a subspace of slowly - varying states @xcite . an additionally applied interaction then causes an _ adiabatic time evolution _ inside this subspace . if the latter coincides with the decoherence - free subspace of the system , the effect of the strong interaction is effectively the same as the effect of continuous measurements whether the system is in a decoherence - free state or not @xcite and weak interactions can be used for the implementation of decoherence - free quantum gates . concrete proposals for the implementation of this idea for ion - trap quantum computing and in atom - cavity systems can be found in refs . @xcite . in this paper we discuss the positive role dissipation can play in a situation where quantum gates are implemented with the help of the adiabatic processes described above . such a scheme is in general relatively robust against parameter fluctuations but any attempt to speed up operations results in the population of unwanted states . however , given the unwanted states possess spontaneous decay rates , the time evolution of the system can become a _ dissipation - assisted adiabatic passage_. even if operated rapidly , the system behaves as predicted for adiabatic processes . the reason is that the no - photon time evolution corrects for any errors due to non - adiabaticity @xcite . as a concrete example , we describe two - qubit gate operations in atom - cavity systems which can be performed twice as fast in the presence of certain decay rates without sacrificing their high fidelity and robustness . the atom - cavity systems provide a promising technology for quantum computing @xcite . the main sources of decoherence are dissipation of cavity photons with rate @xmath0 and spontaneous decay from excited atomic levels with decay rate @xmath1 . some recent proposals for atom - cavity schemes attempt to minimise the population of excited states using strong detunings @xcite ; others use dissipation @xcite . all these schemes are inherently slow which causes relatively high failure rates . regarding success probabilities , the quantum computing schemes @xcite perform much better . we believe that the dissipation - assisted adiabatic passages we describe in this paper contributes to the success of these schemes as well as being a key feature of the original proposal @xcite . over the last three decades quantum optical experiments have been performed studying the statistics of photons emitted by laser - driven trapped atoms and effects have been found that would be averaged out in the statistics of photons emitted by a whole ensemble @xcite . these experiments suggest that the effect of the environment on the state of the atoms is the same as the effect of rapidly repeated measurements and hence can result in a sudden change of the fluorescence of a single atom @xcite . from the assumption of measurements whether a photon has been emitted or not , the quantum jump approach @xcite has been derived . this approach is equivalent to the monte carlo wave - function approach @xcite and the quantum trajectory approach @xcite . suppose a measurement is performed on the free radiation field interacting with a quantum optical system initially prepared in @xmath2 . under the condition of no photon emission and given that the free radiation field was initially prepared in its vaccum state @xmath3 , the ( unnormalised ) state of the system at @xmath4 equals , according to the quantum jump approach @xcite , @xmath5 the dynamics under the conditional time evolution operator @xmath6 , defined by this equation , can be summarised in a hamiltonian @xmath7 . this hamiltonian is in general non - hermitian and the norm of a state vector developing with @xmath7 decreases in time such that @xmath8 is the probability for no emission in @xmath9 . the non - hermitian terms in the conditional hamiltonian continuously damp away amplitudes of unstable states . this takes into account that the observation of no emission leads to a continuous gain of information about the state of the system . the longer no photons are emitted , the more unlikely it is that the system has population in excited states @xcite . in the following we exploit the conditional no - photon time evolution to implement better gate operations . quantum computing with non - hermitian hamiltonians can be performed with high success rates as long as the system remains to a good approximation in a decoherence - free subspace . a state @xmath2 is decoherence - free if populating it can not lead to a photon emission and @xmath10 for all times @xmath11 @xcite . the decoherence - free subspace is therefore spanned by all the eigenvectors of the conditional hamiltonian @xmath7 with real eigenvalues and a time evolution with this hamiltonian leaves the decoherence - free subspace invariant . in general it is very difficult to find a hamiltonian that keeps the decoherence - free subspace invariant _ and _ can be used for the realisation of gate operations . however , it is always possible to add a weak interaction to the conditional hamiltonian @xmath7 , so generating a new conditional hamiltonian @xmath12 . as long as the additional interaction is weak , the decoherence - free subspace constitutes an invariant subspace of @xmath12 to a very good approximation . this can be exploited to generate an adiabatic time evolution inside the decoherence - free subspace according to the effective hamiltonian @xmath13 this hamiltonian can now be used for the realisation of quantum gates . a drawback of this idea is that the effective evolution , which happens on the time scale given by the weak interaction , is very slow . the essential idea of this paper is to ensure that the same net evolution within the decoherence - free subspace is realised with high fidelity even when the system is operated relatively fast , i.e. outside the adiabatic regime , and despite the occurence of errors at intermediate stages . the form of eq . ( [ heff ] ) assures that any error leads to the population of non decoherence - free states . as long as this population is small , there is a very high probability that it will be damped away during the no - photon time evolution . the system behaves effectively as predicted by adiabaticity and the underlying relatively fast process could be called a dissipation - assisted adiabatic passage @xcite . whenever a photon emission occurs , the computation fails and the experiment has to be repeated . naively , one might expect that a finite probability for failure of the proposed scheme also implies a decrease of the fidelity of the gate operation . however , the fidelity under the condition of no photon emission remains close to unity for a wide range of experimental parameters @xcite . moreover , the non - hermitian terms in @xmath12 inhibit transitions into unwanted states and stabilise the desired time evolution ( [ heff ] ) . let us now consider a concrete system . in the following , each qubit is obtained from two different ground states @xmath14 and @xmath15 of the same atom . to implement two - qubit gate operations , the two corresponding atoms are moved inside the optical resonator where both see the same coupling constant @xmath16 . suppose , the 1 - 2 transition in each atom couples resonantly to the cavity mode and @xmath17 and @xmath18 are the annihilation and creation operators for a single photon . the conditional hamiltonian in the interaction picture with respect to the interaction - free hamiltonian can then be written as @xmath19 the last two terms are the non - hermitian terms of the hamiltonian . using eq . ( [ p0cond ] ) one can easily determine the decoherence - free subspace of the atom - cavity system with respect to leakage of photons through the cavity mirrors @xcite . it is spanned by the eigenvectors of the conditional hamiltonian @xmath7 with real eigenvalues assuming @xmath20 and includes all superpositions of the atomic ground states , i.e. the qubits states of the system , and the maximally entangled atomic state @xmath21 . prepared in the state @xmath22 the atoms do not interact with the cavity mode and therefore can not transfer their excitation into the resonator . thus no photon can leak out through the cavity mirrors . populating only these states and performing the gate relatively fast , thereby reducing the possibility for spontaneous emission from the atoms with rate @xmath1 , should result in relatively high gate success rates . in this section we first neglect the spontaneous decay rates , assume @xmath23 and aim at finding laser configurations and rabi frequencies that result in a time evolution with the effective hamiltonian ( [ heff ] ) with respect to the decoherence - free subspace introduced in section [ sect:2.3 ] . in the following , we consider the level configuration in figure [ fig2 ] and denote the rabi frequency with respect to the @xmath24 - 2 transition of atom @xmath25 as @xmath26 . especially , we look for adiabatic processes where the two different time scales in the system are provided by the atom - cavity constant @xmath16 being a few orders of magnitude larger than the rabi frequencies @xmath26 of the applied laser fields , @xmath27 as concrete examples for gate implementations via dissipation - assisted adiabatic passages we describe possible realisations of a two - qubit phase gate and a swap operation . we then show that the same quantum gates can be operated twice as fast with decay rates , while maintaining fidelities above 0.98 . from the discussion in section [ sect:2 ] we know already that the decoherence - free states of the system are the eigenstates of the conditional hamiltonian ( [ cond ] ) with real eigenvalues in the absence of the weak laser interaction . consequently , they are also eigenstates of the interaction hamiltonian of the system , namely @xmath28 to a very good approximation . it is therefore convenient to consider them in the following as basis states . to obtain a complete basis we introduce , in addition to eq . ( [ a ] ) , the symmetric state @xmath29 in the following , @xmath30 denotes a state with @xmath31 photons in the cavity field and the atoms prepared in @xmath32 . we now write the state of the system as a superposition of the form @xmath33 and first calculate the time evolution of the coefficients of the decoherence - free states @xmath34 , @xmath35 , @xmath36 , @xmath37 and @xmath38 . the hamiltonian ( [ nocond ] ) yields @xmath39 ~ , ~ \nonumber \\ \dot c_{0;01 } & = & - { \textstyle { { \rm i } \over 2\sqrt{2 } } } \big [ \omega_0^{(1 ) } \big(c_{0;s } - c_{0;a } \big ) + \sqrt{2 } \omega_1^{(2 ) } c_{0;02 } \big ] ~,~ \nonumber \\ \dot c_{0;10 } & = & - { \textstyle { { \rm i } \over 2\sqrt{2 } } } \big [ \sqrt{2 } \omega_1^{(1 ) } \ , c_{0;20 } + \omega_0^{(2 ) } \big(c_{0;s } + c_{0;a } \big ) \big ] ~,~ \nonumber \\ \dot c_{0;11 } & = & - { \textstyle { { \rm i } \over 2\sqrt{2 } } } \big [ \big ( \omega_1^{(1 ) } + \omega_1^{(2 ) } \big ) c_{0;s } - \big ( \omega_1^{(1 ) } - \omega_1^{(2 ) } \big ) c_{0;a } \big ] ~,~ \nonumber \\ \dot c_{0;a } & = & - { \textstyle { { \rm i } \over 2\sqrt{2 } } } \big [ \big ( \omega_1^{(1 ) } - \omega_1^{(2 ) } \big ) \big ( c_{0;22 } - c_{0;11 } \big ) - \omega_0^{(1 ) } \ , c_{0;01 } \nonumber \\ & & + \omega_0^{(2 ) } \ , c_{0;10 } \big ] ~.\end{aligned}\ ] ] we furthermore consider the derivatives of the amplitudes of the states @xmath40 , @xmath41 , @xmath42 and @xmath43 , @xmath44 - { \rm i } g c_{1;01 } ~ , ~ \nonumber \\ \dot c_{0;20 } & = & - { \textstyle { { \rm i } \over 2 } } \big [ \omega_0^{(1 ) } c_{0;00 } + \omega_0^{(2 ) } c_{0;22 } + \omega_1^{(1 ) } c_{0;10 } \big ] - { \rm i } g c_{1;10 } ~,~ \nonumber \\ \dot c_{0;s } & = & - { \textstyle { { \rm i } \over 2\sqrt{2 } } } \big [ \big ( \omega_1^{(1 ) } + \omega_1^{(2 ) } \big ) \big ( c_{0;11 } + c_{0;22 } \big ) + \omega_0^{(1 ) } c_{0;01 } \nonumber \\ & & + \omega_0^{(2 ) } c_{0;10 } \big ] - \sqrt{2 } { \rm i } g c_{1;11 } ~,~ \nonumber \\ \dot c_{0;22 } & = & - { \textstyle { { \rm i } \over 2\sqrt{2 } } } \big [ \big ( \omega_1^{(1 ) } + \omega_1^{(2 ) } \big ) c_{0;s } + \big ( \omega_1^{(1 ) } - \omega_1^{(2 ) } \big ) c_{0;a } \nonumber \\ & & + \sqrt{2 } \omega_0^{(1 ) } c_{0;02 } + \sqrt{2 } \omega_0^{(2 ) } c_{0;20 } \big ] - \sqrt{2 } { \rm i } g c_{1;s } ~,~ \end{aligned}\ ] ] and the states @xmath45 , @xmath46 , @xmath47 , @xmath48 and @xmath49 , @xmath50 \nonumber \\ & & - { \rm i } g c_{0;02 } ~ , ~ \nonumber \\ \dot c_{1;10 } & = & - { \textstyle { { \rm i } \over 2 \sqrt{2 } } } \big [ \sqrt{2 } \omega_1^{(1 ) } c_{1;20 } + \omega_0^{(2 ) } \big ( c_{1;s } + c_{1,a } \big ) \big ] \nonumber \\ & & - { \rm i } g c_{0;20 } ~,~ \nonumber \\ \dot c_{1;11 } & = & - { \textstyle { { \rm i } \over 2\sqrt{2 } } } \big [ \omega_1^{(1 ) } \big ( c_{1;s } - c_{1,a } \big ) + \omega_1^{(2 ) } \big ( c_{1;s } + c_{1;a } \big ) \big ] \nonumber \\ & & - \sqrt{2 } { \rm i } g c_{0;s } ~,~ \nonumber \\ \dot c_{1;s } & = & - { \textstyle { { \rm i } \over 2\sqrt{2 } } } \big ( \omega_1^{(1 ) } + \omega_1^{(2 ) } \big ) \big ( c_{1;11 } + c_{0;22 } \big ) \nonumber \\ & & - \sqrt{2 } { \rm i } g \big ( c_{0;22 } + \sqrt{2 } c_{2,11 } \big ) ~,~ \nonumber \\ \dot c_{2;11 } & = & - { \textstyle { { \rm i } \over 2 } } \big [ \omega_1^{(1 ) } c_{2;21 } + \omega_1^{(2 ) } c_{2;12 } \big ] - 2 { \rm i } g c_{1;s } ~.~\end{aligned}\ ] ] suppose the system is initially prepared in a qubit state and the population of non - decoherence - free states remains of the order @xmath51 , we can easily eliminate all amplitudes that change on the fast time scale defined by the cavity coupling @xmath16 . setting their derivatives equal to zero and neglecting all terms of second order in @xmath52 and smaller , the differential equations ( [ slower ] ) yield @xmath53 substituting this result into eq . ( [ slowest ] ) and ( [ slow ] ) we obtain further @xmath54 ~,~ \nonumber \\ & & \dot c_{0;22 } = -{\textstyle { { \rm i } \over 2\sqrt{2 } } } \big ( \omega_1^{(1 ) } - \omega_1^{(2 ) } \big ) c_{0;a } ~.~ \end{aligned}\ ] ] this shows that the only way to restrict the time evolution of the system onto the decoherence - free subspace is to choose @xmath55 note that if this is not fulfilled , population leaks directly from the antisymmetric state @xmath38 into the states @xmath43 and @xmath49 . there is no mechanism in the system ( see eq . ( [ onkel ] ) ) that forbids the population of these states . the condition ( [ schwester ] ) can easily be implemented with @xmath56 and the realisation of dissipation - assisted gate operations requires only a single laser field with the respective rabi frequencies @xmath57 . as predicted before , the time evolution of the slowly - varying amplitudes of the system ( [ longer ] ) can be summarised in the hamiltonian @xmath58 ~,~ \nonumber \\&&\end{aligned}\ ] ] which coincides with the effective hamiltonian given in eq . ( [ heff ] ) . the levels and transitions involved in the generation of the effective time evolution of the system are shown in figure [ daap1 ] . the corrections to the effective time evolution in first order @xmath51 can be obtained by performing another adiabatic elimination of fast varying amplitudes using the differential equations ( [ slow ] ) and setting @xmath59 . during gate operations , a small population , given by @xmath60 accumulates in the states @xmath45 , @xmath46 and @xmath61 . there are _ two _ ways to keep these errors small and we use both of them in the following . first , one should turn the laser field off slowly such that @xmath62 with @xmath63 being the gate operation time . then the system can adapt to the changing parameters and the unwanted amplitudes ( [ colder ] ) vanish at time @xmath63 . second , the presence of a finite cavity decay rate @xmath0 can be used to damp away photon population in the cavity mode during the no - photon time evolution . however , @xmath0 should not be too large in order not to disturb the adiabatic evolution . we should also mention that there is another way to guarantee that the system remains within the decoherence - free subspace . this requires the cavity decay rate @xmath0 to be of the same order as @xmath16 , which suppresses the population of _ all _ non decoherence - free states ( including the states @xmath43 and @xmath49 ) , independent of the choice of the rabi frequencies @xmath26 @xcite . indeed , it has been shown that quantum computing using dissipation leads to a realm of new possibilities for the implementations of quantum gate operations @xcite . however , the approach we consider here yields schemes with much shorter gate operation times than the ones reported in ref . @xcite . a simple gate operation that can easily be implemented with the effective hamiltonian ( [ hopt ] ) is the quantum phase gate with @xmath64 this operation changes the state @xmath65 of the second atom into @xmath66 provided that the first atom is in @xmath14 . suppose there is only one laser field coupling to the 0 - 2 transition of atom 1 such that @xmath67 and @xmath68 ~.~\ ] ] the implementation of the unitary operation ( [ phase ] ) then only requires @xmath69 as one can see from solving the time evolution of the hamiltonian ( [ nocond2 ] ) . in the following we choose @xmath70 and @xmath71 . given @xmath72 , the amplitudes of the states @xmath36 and @xmath37 remain unchanged while a minus phase is added to the state @xmath35 after undergoing an adiabatic transition to the excited state @xmath38 and back ( see figure [ daap1 ] ) . that this is indeed the case can be seen in figure [ daap3 ] , which results from a numerical solution of the no - photon time evolution of the system with the hamiltonian @xmath73 for the initial qubit states @xmath74 and @xmath75 . for @xmath23 , fidelities above @xmath76 are achieved for gate operation times @xmath77 . furthermore , the phase gate can be operated in the presence of decay rates . the presence of decay rates allows the scheme to be run twice as fast while maintaining the same high fidelity . looking at the initial state @xmath78 , it can be seen that with @xmath79 the fidelity dips to just over @xmath80 but with @xmath81 the fidelity is always one . the reason is that the presence of cavity decay rates damps away all the population in the states @xmath41 and @xmath46 , at the latest at the end of the operation . maintaining a fidelity close to @xmath82 comes at cost of a significantly lowered success probability , which can be even lower than @xmath83 . for larger values of @xmath0 the success probability would be even smaller . the fidelity given the initial state @xmath84 is only marginally helped by the non - zero @xmath0 . however , a small @xmath85 can further reduce the errors . the reason is that in the non - adiabatic regime unwanted population accumulates in the excited atomic state @xmath86 which is then taken care of by @xmath87 . the competition between greater speed tending to reduce the probability of a failure due to @xmath1 and an increased error due to non - adiabaticity leads to a maximum for the gate success rate of @xmath88 at @xmath89 . another quantum gate that can easily be implemented with the effective hamiltonian ( [ hopt ] ) is the swap operation with @xmath90 unlike the controlled phase gate , the swap gate is not universal . nevertheless , this operation can be very useful since it exchanges the states of two qubits without that the corresponding atoms have to physically swap their places . to implement the time evolution ( [ swap ] ) one should choose @xmath91 and individual laser addressing of the atoms is not required . the effective hamiltonian becomes in this case @xmath92\ ] ] and implements a swap operation if @xmath93 in the following we choose @xmath94 and @xmath95 . figure [ fig4 ] shows the results of a numerical solution of the no - photon time evolution of the system with the hamiltonian @xmath96 for the same parameters as in figure [ daap3 ] . for @xmath23 , fidelities above @xmath76 are achieved as long as @xmath97 . in the presence of the decay rates @xmath81 , @xmath98 and for @xmath99 , the fidelity is well above @xmath100 while @xmath101 . the results for the swap operation are very similar to the results for the phase gate . the reason for this is that the relevant combined level scheme of the system is in both cases about the same ( see figure [ daap1 ] ) . this paper discusses how dissipation can help to increase the performance of quantum gate operations . the focus is on atoms with a @xmath102-type level configuration trapped in an optical cavity but the conclusions can be applied more generally . the concrete examples considered here are two - qubit operations including a controlled phase gate and the swap operation . for @xmath103 , we showed that the gate success rate can be nearly as high as @xmath104 while the fidelity is well above @xmath100 . improved results have only been obtained in refs . the main problem of the proposed quantum computing scheme is spontaneous emission from the atoms . nevertheless , it is very simple , as it requires only a single laser field , and it is widely robust against parameter fluctuations ( see eqs . ( [ opa ] ) and ( [ oma ] ) ) . in the absence of dissipation , the quantum gates described employ adiabaticity arising from the different time scales set by the laser rabi frequencies and atom - cavity coupling constant . however , in the presence of decay rates , like @xmath81 and @xmath85 , the scheme can be operated about twice as fast . the reason is that the underlying process becomes a dissipation - assisted adiabatic passage @xcite . even operated outside the adiabatic regime , the no - photon time evolution corrects for errors and the system behaves as predicted by adiabaticity . the high fidelity comes at a cost of a finite gate failure rate . however , as long as one can detect whether an error occured or not and repeat the computation whenever necessary , this approach can be used to implement high - fidelity quantum computing even in the presence of dissipation . thanks the royal society and the gchq for funding as a james ellis university research fellow . this work was supported in part by the uk engineering and physical sciences research council and the european union through qgates and conquest . shor p w , ed . by s. goldwasser , _ proceedings of the 35th annual symposium on the foundations of computer science _ , ieee computer society ( 1994 ) , p124 . d. deutsch , proc . a * 400 * , 97 ( 1985 ) . l. k. grover , phys . lett . * 79 * , 325 ( 1997 ) . l. m. k. vandersypen , m. steffen , g. breyta , c. s. yannoni , m. h. sherwood , and i. l. chuang , nature * 414 * , 883 ( 2001 ) . f. schmidt - kaler , h. hffner , m. riebe , s. gulde , g. p. t. lancaster , t. deuschle , c. becher , c. f. roos , j. eschner , and r. blatt , nature * 422 * , 408 ( 2003 ) . d. leibfried , b. demarco , v. meyer , d. lucas , m. barrett , j. britton , w. m. itano , b. jelenkovi , c. langer , t. rosenband , d. j. and wineland , nature * 422 * , 412 ( 2003 ) . g. m. palma , k. a. suominen , and a. k. ekert , proc . london ser . a * 452 * , 567 ( 1996 ) . p. zanardi and m. rasetti , phys 79 * , 3306 ( 1997 ) . d. a. lidar , i. l. chuang , and k. b. whaley , phys . * 81 * , 2594 ( 1998 ) . d. bacon , j. kempe , d. a. lidar , and k. b. whaley , phys . lett . * 85 * , 1758 ( 2000 ) . b. misra and e.c.g . sudarshan , j. math . phys . * 18 * , 756 ( 1977 ) . beige , d. braun , b. tregenna , and p. l. knight , phys . lett . * 85 * , 1762 ( 2000 ) ; b. tregenna , a. beige , and p. l. knight , phys . a * 65 * , 032305 ( 2002 ) . a. beige , d. braun , and p. l. knight , new j. phys . * 2 * , 22 ( 2000 ) . j. pachos and h. walther , phys . lett . * 89 * , 18 ( 2002 ) ; j. k. pachos and a. beige , phys . a * 69 * , 033817 ( 2004 ) . e. knill , r. laflamme , and g. j. milburn , nature * 409 * 46 ( 2001 ) . g. g. lapaire , p. kok , j. p. dowling , and j. e. sipe , phys . a * 68 * , 042314 ( 2003 ) . a. beige , phys . a * 69 * , 012303 ( 2004 ) . l. viola and s. lloyd s , phys . a * 58 * , 2733 ( 1998 ) ; l. viola , m. knill , and s. lloyd , phys . lett . * 82 * , 2417 ( 1999 ) . g. s. agarwal , m. o. scully , and h. walther , phys . * 86 * , 4271 ( 2001 ) . p. facchi and s. pascazio , phys . lett . * 89 * , 080401 ( 2002 ) ; p. facchi , d. a. lidar , and s. pascazio , phys . a * 69 * , 032314 ( 2004 ) . a. beige , phys . a * 67 * , 020301(r ) ( 2003 ) . c. marr , a. beige , and g. rempe , phys . a * 68 * , 033817 ( 2003 ) . g. r. guthhrlein , m. keller , k. hayasaka , w. lange , and h. walther , nature * 414 * , 49 ( 2001 ) ; m. keller , b. lange , k. hayasaka , w. lange , and h. walther , appl . b * 76 * , 125 ( 2003 ) . s .- b . zheng and g. c. guo , phys . lett . * 85 * , 2392 ( 2000 ) . e. jan , m. b. plenio , and d. jonathan , phys . a * 65 * , 050302 ( 2002 ) . t. pellizzari , s. a. gardiner , j. i. cirac , and p. zoller , phys . lett . * 75 * , 3788 ( 1995 ) . m. s. shahriar , j. a. bowers , b. demsky , p. s. bhatia , s. lloyd , p. r. hemmer , and a. e. craig , opt . comm . * 195 * , 411 ( 2001 ) . x. x. yi , x. h. su , and l. you , phys . 90 * , 097902 ( 2003 ) ; l. you , x. x. yi , and x. h. su , phys . a * 67 * , 032308 ( 2003 ) . h. walther , adv . chem . phys . * 122 * , 167 ( 2002 ) . h. g. dehmelt , bull . . soc . * 20 * , 60 ( 1975 ) . g. c. hegerfeldt and d. g. sondermann , quantum semiclass * 8 * , 121 ( 1996 ) . j. dalibard , y. castin , and k. mlmer , phys . lett . * 68 * , 580 ( 1992 ) . h. carmichael , _ lecture notes in physics _ , vol * 18 * ( berlin : springer , 1993 ) . r. j. cook , phys . t * 21 * 49 ( 1988 ) . g. c. hegerfeldt , fortschr . phys . * 46 * , 595 ( 1998 ) .

it is commonly believed that decoherence is the main obstacle to quantum information processing . in contrast to this , we show how decoherence in the form of dissipation can improve the performance of certain quantum gates . as an example we consider the realisations of a controlled phase gate and a two - qubit swap operation with the help of a single laser pulse in atom - cavity systems . in the presence of spontaneous decay rates , the speed of the gates can be improved by a factor 2 without sacrificing high fidelity and robustness against parameter fluctuations . even though this leads to finite gate failure rates , the scheme is comparable with other quantum computing proposals .

the top quark has an exceptionally large mass of the order of the electroweak symmetry breaking scale and is naturally expected to have a close connection to new physics @xcite . the run 1 of the fermilab tevatron collider has successfully ended with the discovery of the top quark , but has yielded only a relatively small number of top quark events , which leaves plenty of room for new physics to be uncovered with the tevatron upgrade @xcite in the near future . due to higher statistics , the @xmath4 sample at the upgraded tevatron is expected to provide a sensitive probe of new physics @xcite . a most popular model of new physics is the minimal supersymmetric model ( mssm ) . in this model , the discrete multiplicative symmetry of @xmath0-parity , defined by @xmath5 with spin @xmath6 , baryon number @xmath7 and lepton number @xmath8 , is often imposed on the lagrangian to maintain the separate conservation of @xmath7 and @xmath8 . this conservation requirement is , however , not dictated by any fundamental principle such as gauge invariance or renormalizability . the finiteness of the neutrino mass as suggested by the super - kamiokande and several other neutrino experiments @xcite also implies that lepton numbers may be violated .- violating interactions of the @xmath0-violating mssm can give rise to neutrino masses at the one - loop level @xcite . ] the most general superpotential of the mssm consistent with the @xmath9 symmetry and supersymmetry contains @xmath0-violating interactions which are given by @xcite @xmath10 here @xmath11 ( @xmath12 ) and @xmath13 ( @xmath14 , @xmath15 ) are the left - handed lepton ( quark ) doublet and right - handed lepton ( quark ) singlet chiral superfields , and @xmath16 denotes charge conjugation . @xmath17 are the higgs chiral superfields . the indices @xmath18 , @xmath19 , @xmath20 denote generations and @xmath21 , @xmath22 and @xmath23 are the color indices . the @xmath24 and @xmath25 are the coupling constants of the @xmath8-violating interactions and @xmath26 those of the @xmath7-violating interactions . the non - observation ( so far ) of the proton decay imposes very strong constraints on the product of the @xmath8-violating and @xmath7-violating couplings @xcite . it is thus conventionally assumed in phenomenological studies that only one type of these interactions ( either @xmath8- or @xmath7-violating ) exists . constraints on these @xmath0-parity violating couplings have been obtained from various analyses @xcite and some of their phenomenological implications at lepton @xcite and hadron @xcite colliders have been investigated . it is notable that the bounds on the couplings involving top quark are generally quite weak ( see ref . @xcite for a review ) . in the future precision top quark experiments at the upgraded tevatron , these couplings may either manifest themselves or subjected to further , stronger constraints . in proton - antiproton collisions , the @xmath8-violating top quark interaction @xmath25 can induce tree - level processes such as @xmath27 via slepton exchange in the @xmath2 channel . ( here the subscript @xmath8 stands for chirality , not helicity . ) similarly , the @xmath7-violating @xmath26 coupling gives rise to the process @xmath28 via squark exchange . since the couplings are chiral , these new production mechanisms produce an asymmetry between the left- and right - handed polarized top quarks . this polarization can be a sensitive probe for these couplings due to the fact that both the sm and @xmath0-conserving mssm contributions to the polarization are small and light gluino , which is disfavored by the existing experimental data , the polarization induced by supersymmetric weak and strong interactions could be significant , however @xcite . ] . in ref . @xcite , the contribution of these processes to the _ total _ @xmath4 cross section was studied to constrain the relevant @xmath0-violating couplings . the effect is found to be at most of the level of a few percent . because of the uncertainties in the sm predictions of the @xmath29 production cross section and possible contributions from the @xmath0-_conserving _ mssm interactions @xcite , the total @xmath4 cross section turns out not to be a suitable observable for the r - parity violating interactions . in this paper , we investigate the possibility of probing the @xmath0-violating in several observables including the top quark polarization in @xmath4 production at the upgraded tevatron collider . the top polarization can serve as a sensitive probe of the r - parity violating interactions because of the negligibly small sm or mssm contribution . in terms of the four - component dirac notation , the lagrangian of the @xmath25 and @xmath26 interactions is given by ( notice that @xmath30 ) @xmath31 + { \rm h.c.},\\ \label{lag2 } { \cal l}_{\lambda''}&=&-\lambda''_{ijk } \epsilon_{\alpha\beta\gamma } \left [ ( \tilde d^{k\gamma}_r)^ * \bar u^{i\alpha}_r ( d^{j\beta}_r)^c + \frac12 ( \tilde u^{i\alpha}_r)^ * \bar d^{j\beta}_r ( d^{k\gamma}_r)^c\right ] + { \rm h.c.}\end{aligned}\ ] ] the relevant feynman diagrams for the process @xmath1 via the @xmath8- and @xmath7-violating couplings are shown in fig . it is evident that these amplitudes are proportional to @xmath32 and @xmath33 , respectively . the form of these amplitudes are discussed in some detail in the appendix . here we show the cross section at @xmath34 ( the interference term with the sm @xmath35 amplitude ) , @xmath36 for each @xmath2 , @xmath37 helicity state @xmath38 . for the @xmath8-violating couplings , we find @xmath39 { d\hat\sigma^{\rm new}_{++}\over d\cos\theta^ * } = { d\hat\sigma^{\rm new}_{--}\over d\cos\theta^ * } & = & -{\alpha_s |\lambda'_{i31}|^2 \beta m_t^2\over 18 \hat s^2}\ , { \sin^2\theta^ * \over 1 + 2(m_{\tilde e^i}^2-m_t^2)/\hat s - \cos\theta^*}\;,\\[3\jot ] { d\hat\sigma^{\rm new}_{-+}\over d\cos\theta^ * } & = & -{\alpha_s |\lambda'_{i31}|^2 \beta\over 72 \hat s}\ , { ( 1+\beta ) ( 1-\cos\theta^*)^2 \over 1 + 2(m_{\tilde e^i}^2-m_t^2)/\hat s - \cos\theta^*}\;,\end{aligned}\ ] ] where @xmath40 is the @xmath4 c.m . energy squared , @xmath41 the scattering angle in the @xmath4 c.m . frame , and @xmath42 . a sum over the flavor index @xmath18 is implied . similar processes @xmath43 and @xmath44 occurs through the couplings @xmath45 and @xmath46 , respectively . the amplitudes for these processes are given by the same formulas with obvious substitution of the coupling . we will neglect these processes as the parton distributions of @xmath47 and @xmath48 quarks are small in a proton . the corresponding expressions for the sm ( qcd ) lowest - order amplitude is @xmath49 { d\hat\sigma^0_{++}\over d\cos\theta^ * } = { d\hat\sigma^0_{--}\over d\cos\theta^ * } & = & { 2\pi\alpha_s^2 \beta m_t^2\over 9 \hat s^2}\ , \sin^2\theta^*\;.\end{aligned}\ ] ] the sum of these two contributions give the cross section @xmath50 up to order @xmath34 . when only the polarization of the top quark is observed , we can sum over the @xmath37 helicity @xmath51 integrating over the scattering angle , we obtain @xmath52\ , \log{(1+\beta)^2 + 4m_{\tilde e^i}^2/\hat s \over ( 1-\beta)^2 + 4m_{\tilde e^i}^2/\hat s } \right\}\\ \label{lv2 } \hat\sigma_+^{\rm new } - \hat\sigma_-^{\rm new } & = & \frac{\alpha_s |\lambda'_{i31}|^2}{9\hat s } \left\ { \frac12 - { m_{\tilde e^i}^2-m_t^2\over \hat s } \right.\nonumber\\ & & \left . -{1\over\beta}\left[{m_t^2\over\hat s } - { \bigl(m_{\tilde e^i}^2-m_t^2\bigr)^2 \over \hat s^2 } \right]\ , \log{(1+\beta)^2 + 4m_{\tilde e^i}^2/\hat s \over ( 1-\beta)^2 + 4m_{\tilde e^i}^2/\hat s } \right\}\end{aligned}\ ] ] we define several observables sensitive to the @xmath0-violating interactions . the ( total ) top polarization is given by @xmath53 the hemisphere top polarizations are obtained by restricting the top scattering angle in the @xmath4 c.m . frame to the forward or backward hemisphere . the forward top polarization is defined as @xmath54 and the backward top polarization @xmath55 is similarly defined with @xmath56 . the forward - backward asymmetry of the top quark is given by @xmath57 which can be defined for either a fixed top quark helicity or with the helicities summed . in the case of the @xmath7-violating interaction , the helicity cross sections are obtained from those for the @xmath8-violating case with the replacement @xmath58 and @xmath59 . we have @xmath60 { d\hat\sigma^{\rm new}_{++}\over d\cos\theta^ * } = { d\hat\sigma^{\rm new}_{--}\over d\cos\theta^ * } & = & -{\alpha_s |\lambda''_{31k}|^2 \beta m_t^2\over 18 \hat s^2}\ , { \sin^2\theta^ * \over 1 + 2(m_{\tilde d^k}^2-m_t^2)/\hat s + \cos\theta^*}\;,\\[3\jot ] { d\hat\sigma^{\rm new}_{-+}\over d\cos\theta^ * } & = & -{\alpha_s |\lambda''_{31k}|^2 \beta\over 72 \hat s}\ , { ( 1-\beta ) ( 1-\cos\theta^*)^2 \over 1 + 2(m_{\tilde d^k}^2-m_t^2)/\hat s + \cos\theta^*}\;.\end{aligned}\ ] ] the expression for @xmath61 changes sign in addition to the replacement of the coupling and mass . the forward and backward hemispheres should be also exchanged . the contribution of the electroweak process @xmath62 is known to be small @xcite and will be neglected in the following analysis . it is important to realize here that there is _ no interference _ with the qcd amplitude because of the orthogonal color structure . thus the effect of the @xmath0-violating interaction can be sizable even for a comparable coupling strength . we calculate the cross section @xmath63 for @xmath64 by convoluting the parton cross section @xmath65 discussed above with the parton distribution functions . we use the cteq3l parton distribution functions @xcite with both the renormalization and factorization scales chosen to be @xmath66 . the top quark mass of 175 gev is used . we assume that the qcd correction factors ( the @xmath67 factor ) to @xmath68 and @xmath69 take the same value of 1.7 . for the purpose of estimating the statistical sensitivity , we assume that only the leptonic modes @xmath70 ( @xmath71 or @xmath72 ) are used to identify the top quark . this is because charge measurement is needed for top / antitop identification and the reconstruction of the final state decay products is required for separating the top polarization states from decay angular distribution @xcite . the statistical error for the top polarization is given by @xmath73^{1/2}}{(n_+ + n_-)^{3/2 } } \simeq \frac{1 } { \sqrt{n_+ + n_- } } \;,\ ] ] where @xmath74 and @xmath75 are the numbers of right - handed and left - handed top events . the polarization of @xmath37 can also be used to increase the statistical sensitivity of the data . the total polarizations @xmath76 and @xmath61 have the same magnitude but opposite in sign within our approximation , and the hemisphere @xmath37 polarization can be calculated from the expressions given above . to be conservative , we do not use the @xmath37 polarization in the following analyses . we assume for simplicity that only one of the couplings dominates . for the @xmath8-violating couplings , @xmath77 and @xmath78 are already strongly constrained by atomic parity violation and @xmath79 deep - inelastic scattering @xcite , respectively . we may thus interpret our result as that on @xmath80 , in which case the scalar - tau is exchanged in the process . in the case of @xmath7-violating interactions , none of the relevant couplings have been well constrained by other processes . in fig . 2 , we show the polarizations @xmath61 , @xmath81 , and @xmath55 normalized to @xmath82 versus the scalar - tau mass . the figures can be also read as @xmath83 versus the squark mass with ` forward ' and ` backward ' interchanged . if the coupling is of the order of the weak su(2 ) gauge coupling , a polarization of several % is expected , without contradicting with existing limits . the total polarization is smaller than hemisphere polarizations because of the cancellation between the two hemispheres . for the coupling @xmath80 ( @xmath84 ) , the backward ( forward ) polarization has the largest magnitude of the three . in spite of the smaller number of events , the statistical sensitivity of the backward ( forward ) polarization is higher than that of the total polarization , as may be seen from fig . 3 . because of the small electroweak contribution ( much less than one per cent ) , the top polarization can be a useful probe of the @xmath0-violating couplings . the forward - backward asymmetries for the top quark ( for individual helicities and their sum ) are shown in fig . the size of the effect is similar to the polarizations . the total asymmetry is smaller than the asymmetries of each helicity top events . the @xmath85 limit for @xmath80 ( @xmath84 ) , which is defined by eq . ( [ error ] ) with @xmath86 ( @xmath87 ) , versus scalar - tau ( squark ) mass is shown in fig . 5 for the integrated luminosities of 2 fb@xmath88 ( run 2 ) and 30 fb@xmath88 ( run 3 ) . the current @xmath85 limits from @xmath89 decay at lep - i @xcite are also shown for comparison . note that the limits on @xmath80 obtained from the decay @xmath90 depend on squark mass since the coupling @xmath80 contributes to this decay via the squark - quark loops . but our limits depend on the scalar - tau mass . therefore , @xmath61 and @xmath91 can provide complementary information for the coupling @xmath80 , and the upgraded 2 tev tevatron collider with @xmath92 fb@xmath88 or even lower luminosity can provide meaningful information on this kind of new physics . as the polarization grows with energy , one can probe further parameter space in the couplings and masses at higher energies . we have studied the possibility to probe the @xmath0-parity violating interactions of the top quark at the tevatron collider . obviously , @xmath0-violating decays of squarks provide a way to limit these interactions @xcite . we have shown that even when the squark is rather heavy and the production cross section is low , the @xmath0-violating interactions can affect the top quark pair production cross section via slepton ( or squark ) exchange . as these couplings are chiral , their contributions can lead to sizable polarization and forward - backward asymmetry for the top quark , that exceed the level expected from the standard model electroweak interactions . hence , we expect that the forthcoming new runs at the tevatron collider with main injector can improve the constraints on those couplings . jmy acknowledges jsps for financial support . this work is supported in part by the grant - in - aid for scientific research ( no . 10640243 ) and grant - in - aid for jsps fellows ( no . 97317 ) from the japan ministry of education , science , sports , and culture . bly acknowledges the support by a nato collaborative grant . bly would also like to thank professor zhongyuan zhu and professor ting - kuo lee , respectively at the institute of theoretical physics , chinese academy of sciences , beijing and the national center of theoretical sciences , hsin chu , for their kind hospitalities and support . here we list the amplitudes for @xmath93 used in the paper . the feynman amplitudes are as follows : the helicity amplitudes for the process may be calculated from these invariant amplitudes . the amplitude for the helicity combination @xmath100 has the structure @xmath101 where @xmath102 , @xmath103 , @xmath104 the scattering angle ( the direction of the final @xmath2 with respect to the initial @xmath105 ) , and @xmath106 is the wigner d function ( rotation matrix ) for the spin-1 representation . since chirality is conserved , the process occurs for only two of the initial states with @xmath107 . the standard model contribution is @xmath108 the slepton exchange contribution exists only for @xmath109 because of the chirality structure of the interaction ( only @xmath110 interacts ) : @xmath111 the squark exchange contribution is also for @xmath109 only : @xmath112 where @xmath113 is the top c.m . velocity , @xmath114 , and the color factors are given by @xmath115 for some of the general description of new physics in top quark sector , see : r. d. peccei and x. zhang , 337 , 269 ( 1990 ) ; r. d. peccei , s. peris and x. zhang , 349 , 305 ( 1991 ) ; g. j. gounaris , f. m. renard , and c. verzegnassi , 52 , 451 ( 1995 ) ; k. whisnant , j. m. yang , b .- young and x. zhang , 56 , 467 ( 1997 ) ; j. m. yang and b .- young , 56 , 5907 ( 1997 ) ; g. j. gounaris , d. t. papadamou , and f. m. renard , 76 , 333 ( 1997 ) . , edited by d. amidei and c. brock , fermilab - pub-96/082 ; a. p. heinson , in _ qcd and high - energy hadronic interactions , proceedings of the xxxist rencontre de moriond _ , les arcs , france , 1996 , edited by tran thanh van ( edition frontiere , gif - sur - yvette , france , 1996 ) , p. 43 ( hep - ex/9605010 ) . for some of the systematic studies of probing new physics from @xmath4 events at tevatron , see : c. t. hill and s. j. parke , 49 , 4454 ( 1994 ) ; k. hikasa , k. whisnant , j. m. yang and b .- young , 58 , 114003 ( 1998 ) . for some of the studies of probing anomalous top quark dipole moments in @xmath4 production at tevatron , see : d. atwood , a. aeppli and a. soni , 69 , 2754 ( 1992 ) ; d. atwood , a. kagan , t. g. rizzo , 52 , 6264 ( 1995 ) ; k. cheung , 53 , 3604 ( 1996 ) ; p. haberl , o. nachtmann and a. wilch , 53 , 4875 ( 1996 ) ; t. g. rizzo , 53 , 6218 ( 1996 ) ; d. silverman , 54 , 5562 ( 1996 ) . super kamiokande collaboration , y. fukuda _ et al . _ , 81 , 1562 ( 1998 ) ; t. kajita , talk at neutrino 98 , takayama , japan , june , 1998 ; for a recent review of all relevant data on neutrion oscillations , see j.m . conrad , summary talk at ichep 98 , hep - ex/981109 . for some of the earliest references on the phenomenology of r - violating supersymmetry , see : l. hall and m. suzuki , 231 , 419 ( 1984 ) ; j. ellis _ et al . _ , 150 , 142 ( 1985 ) ; g. ross and j. valle , 151 , 375 ( 1985 ) ; s. dawson , 261 , 297 ( 1985 ) ; r. barbieri and a. masiero , 267 , 679 ( 1986 ) . f. zwirner , 132 , 103 ( 1983 ) ; r. n. mohapatra , 34 , 3457 ( 1986 ) ; m. hirsch , h. kleingrothaus and s. g. kovalenko , 75 , 17 ( 1995 ) ; k. s. babu and r. n. mohapatra , 75 , 2276 ( 1995 ) ; 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the lepton or baryon number violating top quark interactions in the supersymmetric standard model with @xmath0 parity violation contribute to the process @xmath1 at the tree level via the @xmath2- or @xmath3-channel sfermion exchange . since these interactions are chiral , they induce polarization to the top quark in the @xmath4 events at hadron colliders . we show in this article that the polarization can be a useful observable for probing these interactions at the upgraded fermilab tevatron collider , because the polarization is expected to be very small in the standard model . = # 1,mod . phys . lett . a * # 1 * , # 1,nucl . phys . * b#1 * , # 1,phys . lett . b * # 1 * , # 1,phys . rev . d * # 1 * , # 1,phys . rev . lett . * # 1 * , # 1,phys . rep . * # 1 * , # 1,z . phys . c * # 1 * ,

Police find DNA match to Swedish reporter who is believed to have been killed on a homemade submarine Police in Denmark have identified a headless torso found in the Copenhagen waterside as that of Swedish journalist Kim Wall, who police believe was killed on board a Danish inventor’s homemade submarine. Speaking at a press conference on Wednesday morning, Copenhagen police’s vice-president, Jens Møller, said metal weights had been attached to the body to prevent it from floating to the surface. “The body bears the mark of having, most likely, been inflicted deliberate damage with the purpose of ensuring that gasses can pass out of the body – possibly in an attempt to avoid that a body rises from the seabed,” Møller said. He also said DNA taken from a hairbrush and toothbrush belonging to 30-year-old Wall had matched that of blood found on the submarine. Peter Madsen, a Danish inventor about whom Wall is believed to have been writing a feature article, was charged with manslaughter last week. He told a court hearing this week that Wall died in an accident on his vessel and that he “buried” her at sea. My friend Kim Wall's disappearance in Denmark shows: female journalists face danger everywhere Read more This marked a change from a previous statement in which he claimed to have dropped off Wall alive on the tip of an island off Copenhagen late on 10 August before the vessel sank. Madsen denies manslaughter. Wall’s mother, Ingrid, posted on Facebook on Wednesday: “We cannot see the end of the disaster yet, and a lot of questions are still to be answered. “The tragedy has hit not only us and other families, but friends and colleagues all over the world. During the horrendous days since Kim disappeared, we have received countless evidence of how loved and appreciated she has been, as a human and friend as well as a professional journalist. From all corners of the world comes evidence of Kim’s ability to be a person who makes a difference.” Facebook Twitter Pinterest Peter Madsen’s private submarine sits on a pier in Copenhagen harbour. Photograph: Jens Dresling/AP Originally from Sweden, Wall had degrees from Columbia University and the London School of Economics, and had written for publications including the New York Times, Foreign Policy, Time and the Guardian. Danish authorities had been searching for the reporter since she failed to return from an interview with Madsen on board the Nautilus. She was last seen on the vessel by several people in waters off Copenhagen on the evening of 10 August. Her boyfriend reported her missing in the early hours the next day. The submarine was later also reported missing, and rescue crews located it shortly after 10am on 11 August in Køge Bay, south of the Danish capital. At about 11am, Madsen jumped into the water after the submarine started to sink. He told personnel on the boat that rescued him that there had been a problem with the ballast tank and something had gone wrong when he tried to repair it. Police refloated the Nautilus and towed it into harbour for investigation, later suggesting that Madsen may have sunk the boat on purpose to hide evidence. Madsen appeared before a judge on 12 August for preliminary questioning. The case is not open to the public to protect further investigations, police said. Kim Wall timeline Kim Wall timeline On Wednesday Madsen’s lawyer said her client still maintains that Wall died accidentally, and that the discovery of the journalist’s torso did not mean he was guilty of killing her. “It doesn’t change my client’s explanation that an accident happened,” Betina Hald Engmark told Danish tabloid BT. “No matter what, we find it very positive that she has been found now.” An entrepreneur, artist, submarine builder and aerospace engineer, Madsen, 46, nicknamed Rocket, has enjoyed a cult status in his native Denmark. For years, a team built around him and the aerospace engineer Kristian von Bengtson have worked on designing a rocket-driven spacecraft. The Nautilus, which was Madsen’s third design for a “midget submarine” vessel and became the largest privately built submarine when it was unveiled in 2008, has been his most spectacular invention to date. Measuring almost 18 metres and weighing 40 tonnes, it can be operated by one person from its control room. Madsen was known to regularly take fans and submarine enthusiasts on tours through the Øresund strait. Able to submerge in approximately 20 seconds, the boat can carry up to eight people to 100 metres below sea level. On Tuesday a support group set up in his honour distanced itself from the inventor. “The dream is burst. In view of the latest information released by the Copenhagen police today, there is regrettably no way for us to continue as part of the Raket-Madsen Support Group,” the group’s president announced on its website. Danish police said that in light of the findings they would look afresh into unsolved cases such as the murder of a Japanese tourist in 1986. Body parts of 22-year-old Kazuko Toyonaga were found in plastic bags at separate locations in the waters outside Copenhagen almost a month after the student disappeared on her travels through Scandinavia. Jessica Reed, the Guardian’s US features editor, who commissioned Wall to write articles on a range of subjects, including the last freakshow in America, Voudou in Haiti, real-life vampires and an eccentric American couple who had befriended Gaddafi, paid tribute to the reporter. “It would be sad to let this tragedy define what Kim’s life was,” Reed said. “She should be remembered for her insatiable curiosity, and her drive to find stories which no other journalist had touched before. “She was deeply interested in the lives of outliers, people who lived their lives in their own terms. Her passion for her subjects was infectious, and as such she was an absolute pleasure to work with. She was a true professional.” ||||| Media playback is unsupported on your device Media caption Kim Wall's death: What we know so far A headless torso found in waters off Denmark has been identified as missing Swedish journalist Kim Wall, Danish police say. DNA from the torso matched that from Ms Wall's hairbrush and toothbrush. Chief investigator Jens Moller Jensen said that the torso had been weighted down with metal in an apparent attempt to stop it floating. Ms Wall was last seen alive on 10 August as she departed on a submarine trip with inventor Peter Madsen. The submarine sank hours after the search for Ms Wall began, after her partner reported that she had not returned from the trip. Mr Madsen, who designed and built the submarine, was charged with negligent manslaughter and is in detention. He initially said he had dropped her off safely near Copenhagen, but has since said she died in an accident and that he had "buried" her at sea. Danish police believe the 40-tonne submarine was deliberately sunk by Mr Madsen. Traces of blood have been found inside the submarine, and they also match Ms Wall. The remains were found on a beach south of Copenhagen on Monday. Mr Jensen would not comment on the cause of death but said forensic investigations were still being carried out and police were looking for the rest of her body. As well as the metal attached to the torso, Mr Jensen said the remains were mutilated in what appeared to be an attempt to ensure that decomposition gases passed out of the body, to make it less likely to float. Kim Wall's mother Ingrid wrote of the family's "boundless sorrow" at the news that her daughter's remains had been found. "During the horrendous days since Kim disappeared, we have received countless examples of how loved and appreciated she was, as a person and as a friend, as well as a professional journalist," Ingrid Wall said in a family statement released on Facebook. "From all corners of the world we have received testimony to how she was able to be a person who made a difference." Image copyright Ritzau Foto Image caption Mr Madsen and Ms Wall were photographed just before departing on 10 August What happened to Kim Wall? Ms Wall, 30, was reported missing by her boyfriend in the early hours of 11 August, after she failed to return from the trip on Peter Madsen's homemade submarine, the Nautilus. A freelance journalist who had written for the Guardian, New York Times and South China Morning Post, she is said to have been researching a feature about the inventor and the Nautilus, which he built in 2008 with crowdfunding. Emergency services scoured the area of sea to the east of Copenhagen and the submarine was eventually spotted from a lighthouse south of the Oresund bridge between Denmark and Sweden. Within 30 minutes, the vessel had sunk and Mr Madsen had to be rescued. For 10 days, the search for the journalist continued. A torso was found by a passing cyclist on a beach near Koge Bay on Monday. Police said the next day that the arms, legs and head had been deliberately cut off. They finally confirmed it was Kim Wall in a tweet early on Wednesday. Mr Madsen's lawyer, Betina Hald Engmark, said the news that the torso was Ms Wall did not change her client's position, that the journalist had died in an accident. He was "very relieved" the torso had been identified, she told Danish media. "He wants nothing else than for this case to be cleared up." Peter Madsen pleaded not guilty in a closed-door judicial hearing earlier this month. Copenhagen police are re-examining old cases, as is standard in such investigations, according to the chief prosecutor, including the death of a 22-year-old Japanese woman, whose torso was found in Copenhagen harbour in 1986. That case has never been solved.

– Police in Sweden have made a grisly confirmation: The torso of a woman found near the shore in Copenhagen is indeed that of missing journalist Kim Wall, reports the BBC. And it appears that somebody tried to make sure her body sank to the ocean bottom and stayed there. Police say the torso had been deliberately attached to metal. Worse: “Damage seems to have been done to the torso in an attempt to ensure that air and gases escape and the body won’t drift to the surface,” says a police official, per the Guardian. The 30-year-old had been missing since getting on a submarine built by inventor Peter Madsen on Aug. 10. Madsen's story keeps changing: He initially told police he had dropped her off safe and sound, then said he had buried her at sea after she died aboard the sub in an accident. Police have charged him with manslaughter, suggesting that he killed Wall during their trip, then deliberately sank his own sub in an attempt to hide the evidence. It has since been refloated, and investigators found blood inside. Madsen's attorney says the torso's identification doesn't change his client's story, that she died in an accident and he disposed of her body (her head, arms, and legs were cut off) as best he could. Police used DNA samples from Wall's hairbrush and toothbrush to identify the torso. The case has now become “the most spectacular murder case in Danish history," in the words of Christian Jensen, editor of Denmark’s largest daily, Politiken, per the New York Times.

rotation curves ( hereafter rc ) of disk galaxies do not show any keplerian fall - off and do not match the distribution of the stellar ( plus gaseous ) matter . as a most natural explanation , this implies an additional invisible mass component ( rubin et al . 1980 ; bosma 1981 , persic & salucci , 1988 ) that becomes progressively more conspicuous at outer radii and for the less luminous galaxies ( e.g. : persic & salucci , 1988 ; broeils , 1992 ) . the distribution of matter in disk systems has become a crucial benchmark for the present understanding of the process of galaxy formation . time is ripe that we can address , with the help of the available observational scenario , crucial questions : i ) has the dm an universal distribution reflecting its very nature ? ii ) how and why the dark - to - luminous mass ratio and other dark and luminous physical quantities vary in objects of different mass ? 0.2 cm -0.2 cm it is well known that numerical simulations performed in the framework of the currently favored theory of structure formation , @xmath0 cold dark matter , predict a well - defined density profile for the virialized halos ( navarro , frenk and white , 1996 ) . furthermore , the mechanism of galaxy formation , as currently understood , involves the cooling and the condensation of pristine hi gas inside the gravitational potential well of dm halos , the transformation of part of this gas into stars and finally the feedback of the latter on the former , through sn explosions . it is widely accepted that the mass distribution of spiral galaxies , we can derive from observations , bears the imprint of the nature and the cosmological history of the dm , its interaction with the lm and it highlights the astrophysical processes that have turned ( some of ) the pristine infalling gas into a stellar disk . it is worth to define the dark matter in the following way : let us set @xmath1 the mass distribution of the gravitating matter and @xmath2 that of the baryonic `` luminous '' matter , both obtained from observations . realized that these distributions do not match , i.e. @xmath3 , we introduce a dark mass component with mass profile @xmath4 such that : @xmath5 with this definition it is immediate that the study of the dm phenomenon involves the _ slope _ of the rc rather than its amplitude and must start from a proper knowledge of the luminous matter distribution . in spirals , this has three components : a stellar bulge , a thin stellar disk and an extended thin hi disk . within the aim of this paper the latter component plays little role and it will be neglected unless we consider individual hi - rich objects . the first component , instead , it is important in early type spirals , not considered here and then we redirect the reader to noordermeer et al . ( 2007 ) . the luminous matter in spirals is distributed in thin disk with surface luminosity ( freeman , 1970 ) : @xmath6 with @xmath7 the disk scale - length ; @xmath8 the central value ; it is useful to define @xmath9 as the `` size '' of the stellar disk , whose luminosity is @xmath10 . in fig . 1 we plot the coadded ( i - band ) light profiles of 616 late types spirals arranged in 11 luminosity bins as a function of radius , expressed in units of optical radius . we realize that the light profile does not depend on galaxy luminosity and it is well represented by a freeman profile . although the mass modelling of some individual object may require to consider non - exponential stellar disks , eq ( 1.2 ) well represents the typical distribution of stars in late type spirals . similarly , the moderate radial variations of the stellar mass - to - light ratios in spirals will be neglected as they are irrelevant for the present issues ( portinari & salucci , 2007 ) . -0.7 cm -0.7 cm finally we assume flat cosmology with matter density parameter @xmath11 and hubble constant @xmath12 , at the present time , the size @xmath13 and the mass @xmath14 of a virialized halo are related by : @xmath15 in self - gravitating systems in full centrifugal equilibrium , the circular velocity @xmath16 at a radius @xmath17 is linked to the gravitational field @xmath18 by @xmath19 . in spirals , we measure the rotation velocity @xmath20 , i.e. the projection on the line of sight of the tangential velocity in cylindric coodinates . let us notice that : @xmath21 , where the latter defines non - axysimmetric motions unrelated to the central potential . @xmath20 measures the gravitational field only when the latter motions are negligible . the discovery , at radii @xmath22 , of the radial tully - fisher relation ( yegorova & salucci , 2007 ) , i.e. of an ensemble of tf - like , statistically independent , low scatter relationships between the galaxy absolute magnitude and its _ rotation _ velocity ( see fig . 2 ) : @xmath23 where @xmath24 , and @xmath25 , @xmath26 are the slope and zero - point of the relations , indicates that the rc s are good gravitational field tracer . more specifically , the fact that in any object and at any radius , the rotation velocity can be predicted just by the galaxy luminosity implies that @xmath27 is generally negligible . a similar conclusion is reached when we reproduce the innermost regions of spirals rc s with mass models with the luminous matter alone , that leaves no space both for dm and for significant non circular motions ( ratnam et al . , 2000 ) . the kinematical properties of sb - im spirals led to the _ universal rotation curve ( urc ) paradigm _ , pioneered in persic and salucci ( 1991 ) and set in persic , salucci & stel ( 1996 , hereafter pss ) . we can state that ( see also salucci et al , 2007 ) the rcs can be generally represented out to their virial radius by @xmath28 , i.e. by a _ universal _ function of radius , tuned by some galaxy property @xmath29 , such as the luminosity or the virial mass that serves as galaxy identifier . the radius can be measured in three coordinate systems @xmath30 : the physical coordinate , and coordinates focused on the luminous and the dark matter distributions respectively . -0.4truecm -0.2truecm -0.1 cm the data used to build the urc are 1 ) 616 rcs that are first arranged in 11 luminosity intervals spanning the whole @xmath31-band luminosity range @xmath32 , with each luminosity bin having @xmath33 velocity measurements , and then coadded by arranging the latter in radial bins of size @xmath34 . this builds 11 synthetic curves @xmath35 out to @xmath36 ( see pss ) , free from most of the observational errors and non - axisymmetric disturbances present in individual rcs . these rc s result very smooth and with a very small intrinsic variance , but showing a very strong luminosity dependence ( see also catinella et al , 2006 ) b ) the empirical relationship between rc slope at 2 @xmath37 and @xmath38 ( see pss ) c ) the halo virial velocity @xmath39 , obtained from the disk mass vs. virial mass relationship ( see shankar et al . , 2006 ) . the _ urc paradigm _ , i.e. the idea according to which halo mass ( or the disk mass ) , eventually involving few other quantities , `` determines '' at any radii the circular velocity of any spiral within an error that is typically much smaller than the true variations that the rc shows in galaxies and among galaxies is implemented by the urc _ function _ , an analytical curve we construct as the sum in quadrature of the disk and halo contributions to the circular velocity , meant to be the observational counterpart of the nfw velocity profile . then , we set : @xmath40 . from ( 1.2 ) the disk term is : @xmath41 where @xmath42 and @xmath43 and @xmath44 are the modified bessel functions computed at @xmath45 . -.8truecm -0.4truecm -0.2 cm for the dm term we assume that the dark halo follows a salucci & burkert ( 2000 ) profile , a cored distribution that can converges to a nfw one at outer radii @xmath46 @xmath47 is the core radius and @xmath48 the central density density . then : @xmath49 \big\}~.\ ] ] then , the urc function , has three free parameters @xmath48 , @xmath47 , @xmath50 that are obtained from fitting @xmath51 and the other data specified above . -0.2 cm -0.1 cm in fig . 3 we show @xmath52 , the urc with the radius expressed in physical units and the objects identified by the halo virial mass ; each line refers to a given halo mass in the range @xmath53 ; the halo mass determines both the amplitude and the shape of the curve . note the contribution of the baryonic component , negligible for small masses but increasingly important in the larger structures . in fig . 4 we frame the urc from a full dm perspective by plotting @xmath54 , @xmath55 is the radial `` dark '' coordinate , and the urc is normalized by @xmath56 . the urc shows that the dm halos and stellar disks are both self - similar , but the whole system is not , likely due to the baryons collapse that has have broken it in the innermost @xmath57 of the halo size . let us notice that the rc s of spirals are _ critically _ not flat : their rc slopes take all of sort of values from that of a solid - body system ( i.e. + 1 ) to that of an almost newtonian point - mass ( i.e. - 1/2 ) . the maximum of the rc occurs at very different radii , for galaxies of different mass , viz . at @xmath58 for the most massive objects and at @xmath59 for the least massive ones . the existence of systematical properties of the mass distribution in spirals was first claimed by persic and salucci ( 1988 ) and then successively confirmed by independent works ( broeils , 1992 ; pss ; rhee , 1997 ; swaters , 1999 ) . however , until now it has been considered by current theory of galaxy formation only in a limited way . likely , this is a consequence of the theoretical prejudice that the cosmological galaxy formation process did not leave relevant features in the distribution of matter in galaxies and of the difficulties that simulations have in `` reproducing '' reasonable disk systems . however , after salucci et al ( 2007 ) , we believe that , in order to understand the whole process of their formation we must take into account the rich scenario of the dark - luminous interplay occurred in galaxies . -0.2 cm -0.5truecm -0.1truecm the mass distribution in spirals is obtained by mass modelling two very different and complementary kinematical set of data _ a ) _ a large number of _ individual _ rc s of objects of different luminosity and _ b ) _ the urc ( see fig . 5 ) , that , let us remind , originates from _ coadded _ rc s ; noticeably , the results obtained from these two different sets of data are very similar , indicating so that they are robust and reliable . a clear scenario of the mass distribution emerges , see fig . 6 : @xmath60 the stellar disk dominates the galaxy s inner region out to the radius @xmath61 at which the dm halo contribution starts to take over the stellar one . this sets the properties of the radial tully fisher relation and yields to the paradigm of the inner baryon dominance : the inner portions of the ( observed ) rc that can be accounted by the stellar matter alone are indeed saturated by this component . @xmath60 at any radii , smaller lower luminosity objects have more progressively more proportion of dark matter i.e. a larger dark - to - stellar mass ratio . in detail , the disk mass is @xmath62 at small virial masses , @xmath63 and @xmath64 at larger masses , @xmath65 . the baryonic fraction is always much smaller than @xmath66 , i.e. the cosmological value and it ranges between @xmath67 to @xmath68 in line with is the wellknown evidence that sn explosions have removed ( or made never condense ) a very large fraction of the original hi material . @xmath60 smaller spirals are denser , with the central density spanning 2 order of magnitudes over the mass sequence of spirals . if this reflects the background density at the formation time , it indicates that the present day population of spirals has been hierarchically formed from @xmath69 to @xmath70 , and , since then , it has experienced very little merging . @xmath60 the structural parameters of the mass distribution , @xmath48 , @xmath50 , @xmath71 , @xmath47 are remarkably all related , see figure ( 4 ) and fig ( 11 ) of pss . notice that , although this evidence is connected with the urc paradigm , however it is not directly implied by it nor it implies it . @xmath60 the stellar mass - to - light ratio is found to lie between 0.5 and 4 . the values of disk masses derived as above agree very well with those obtained by fitting their sed with spectro - photometric models ( salucci , yegorova , drory , 2007 ) @xmath60 the hi component is almost always below the kinematical detectably . however , in low mass systems it can not be neglected in the baryonic budget since it is more prominent than the stellar disk . a fundamental prediction of the cosmological ( @xmath0 ) cold dark matter simulations is that virialized dark matter halos have an universal spherically averaged density profile @xmath72 ( navarro , frenk & white , 1997 ) @xmath73 where @xmath74 and @xmath75 are strongly correlated ( e.g. wechsler et al , . 2002 ) , we have : @xmath76 , that sets the region of the inner cusp . the above profile converges , at small radii , to a power - law of index -1 , although , according to higher resolution simulations , the actual value of the index reaches about -1.35 ( e.g. moore et al 1999 , navarro et al . 2004 ) . the cdm predictions can be confronted with observations : rc s of disk galaxies , in fact , probe the crucial region @xmath77 . flores & primack ( 1994 ) , moore ( 1994 ) claimed , for some dwarfs , a tension between the kinematical data and the predictions of simulations : dm halos seemed to prefer cored density distributions rather than cuspy ones ( see also van den bosch and swaters , 2001 ; weldrake et al . 2003 ) . 0.2 cm 0.2 cm the importance of the issue , that concerns the very nature of dark matter , and the fact that these early results were questioned on several aspects , has triggered new investigations characterized by the study of few proper test - cases but with higher quality kinematical data and by means of a properly devised analysis ( gentile et al . , 2004 ) . these improvements were necessary : to obtain reliable dm profiles requires extended , regular , homogeneous rc s reliable up to their second derivative and free from deviations from the axial symmetry . then , up to now , few tenths of objects have qualified to undergo such critics - free investigation ( e.g. the list in donato et al . , 2004 ; simon et al . ; 2005 , gentile et al . , 2005 ; 2007 ; de blok , 2007 ) . in all these cases data and simulations were found in plain disagreement on _ three _ different aspects : the best - fit disk + nfw halo mass model a ) fits the rc poorly and it implies b ) an implausibly low stellar mass - to - light ratio and c ) an unphysical high halo mass . 0.1 cm 0.1 cm as an example , it is worth to discuss in detail the case of the nearby dwarf galaxy ddo 47 ( gentile et al 2005 ) . the hi observations have adequate resolution and sensitivity , showing that the hi 2-d kinematics is very regular , with a well - behaved velocity field . the observed velocity along the line of sight @xmath78 has been decomposed in terms of harmonic coefficients : @xmath79 $ ] where @xmath80 is the azimuthal angle , @xmath81 is the systemic velocity , @xmath82 is the rotation velocity ( see schoenmakers et al . , 1997 ) ; it is found that the coefficients @xmath83 , @xmath84 @xmath85 have a small amplitude ( see fig . 7 ) that excludes significant global elongation and lopsidedness of the potential and detects non - circular motions with amplitude and radial profile very different from that necessary to hide a cuspy density distribution in the observed rotation curve . the rc mass modelling , shown in fig . ( 8) , finds that the ddo 47 dark halo has a core radius of about 7 kpc and a central density @xmath86 g @xmath87 , i.e. a _ much _ shallower distribution than that predicted by the nfw profile . in all cases studied up to date a serious data - prediction discrepancy emerges , that becomes definitive when we remind that the actual @xmath88 halo profiles are steeper than the standard nfw ones considered here and that the baryonic adiabatic collapse has likely contracted them further . on the other hand , this discrepancy found in a relatively small number of objects can not be extended to the _ whole _ population of spirals , which is still not sufficiently investigated . let us stress that there is not shortage of proposals to explain the `` density core phenomenon '' within the @xmath0cdm scenario itself ( e.g tonini et al 2007 ) . the distribution of luminous and dark matter in galaxies shows amazing properties and a remarkable systematics that make it as one of the hottest cosmological issues . there is no doubt that this emerging observational scenario will be decisive in guiding how the @xmath88-based theory of galaxy formation must evolve to meet the challenge that the observational data are posing . [ sec : concl ] noordermeer e. , van der hulst j.m . , sancisi r. , swaters r.s . , van albada t.s . , 2007 , mnras , 376 , 1513 navarro j. f. , et al . , 2004 , mnras , 349 , 1039 navarro , j.f . , frenk , c.s . , & white , s.d.m . 1996 , apj , 462 , 563 salucci , p , yegorova i.a . , drory , n. , 2007 , submitted shankar , f. , lapi , a. , salucci , p. , de zotti , g. , danese , l. 2006 , apj , 643 , 14 schoenmakers , r. h. m. , franx , m. , de zeeuw , p. t. , 1997 , mnras , 292 , 349 simon , j. d. , bolatto , a. d. , leroy , a. , blitz , l. , gates , e. l. 2005 , apj , 621 , 757 swaters , 1999 , ph.d . thesis , groningen university tonini c. , lapi a. , salucci p. , 2006 , apj , 649 , 591

in the past years a wealth of observations has allowed us to unravel the structural properties of the dark and luminous mass distribution in spirals . as result , it has been found that their rotation curves follow , out their virial radius , an universal function ( urc ) made by two terms : one due to the gravitational potential of a freeman stellar disk and the other due to that of a dark halo . the importance of the latter is found to decrease with galaxy mass . individual objects reveal in detail that dark halos have a density core , whose size correlates with its central value . these properties will guide @xmath0cdm cosmology to evolve to match the challenge that observations presently pose .

Do you agree or disagree with the Casey Anthony jury's verdict of not guilty of first-degree murder? Poll: Do you agree or disagree with the Casey Anthony jury's verdict? Wherever she is, whatever she is doing, Casey Anthony most likely will have to take a break within the next two days and report to a Florida probation officer. Orange Circuit Judge Stan Strickland signed amended court documents Monday requiring Anthony to serve one year of supervised probation — as he originally intended when he sentenced her in a check fraud case last year. "From my reading of this, she should be reporting to probation in Orlando probably within 72 hours," Strickland said early Monday. "I suspect she's going to be required to report to probation." Meanwhile, Department of Corrections officials confirmed they have reached out to Casey Anthony's attorneys about having her report to probation. "We're in contact with Casey Anthony's attorneys to set up her first report visit," spokeswoman Gretl Plessinger said. "We're prepared to move forward with the court order." According to the revised court order, Anthony will have to report in person by early Thursday, Plessinger said. However, experts who have followed the case dispute whether the amended language will have the legal force to compel Anthony to serve probation now. Some suggest her defense team might take the issue to an appeals court. "If she doesn't report, she'll be in violation of her probation, unless something legally happens and we're told to hold off," Plessinger said. But if the sentence sticks, any violation of probation could send Anthony back to jail. It's likely Anthony's defense team will challenge this turn of events, and say she should not serve probation because she already did that while in jail. An argument claiming "double jeopardy" is expected. Members of Anthony's defense team could not be reached for comment Monday. Plessinger said it wasn't clear yet where or exactly when Anthony would have to report. Also, she said, if Anthony's team cites special circumstances in this case, DOC might consider security measures. Anthony's complicated sentence involved 13 counts of check fraud, theft and fraudulent use of personal-identification information involving her friend Amy Huizenga. She pleaded guilty and Strickland ordered adjudication withheld on seven counts against her and adjudicated her guilty on six felony counts in January 2010. Confusion about probation While Monday's actions brought some clarity to the probation situation, confusion lingered late last week over whether Anthony should have to serve a year of probation in her check-fraud case now that she is out of jail. Strickland said on Thursday that his intention in sentencing Anthony last year was that she should go on supervised probation if released from custody. But Corrections officials interpreted Strickland's order as meaning that Anthony should serve her probation while still in jail awaiting trial in connection with the 2008 death of her daughter Caylee Marie. DOC terminated Anthony's probation on Jan. 24. And Anthony, 25, left the Orange County Jail on July 17 with no restrictions following her acquittal at trial in the murder case last month. She was convicted last month of four misdemeanor charges of lying to law enforcement, but ended up receiving mostly credit for time served in jail for those counts. On Friday, Plessinger said DOC would apply supervised probation now, if the court issued an amended order in the check fraud case. That order, commonly referred to as the minutes, lacked the specific wording "upon release." It was amended and Strickland signed it Monday. But case notes provided by the DOC through its Probation & Parole Services, show that Casey Anthony was contacted repeatedly by probation officials while she was awaiting trial in the Orange County Jail. ||||| Casey Anthony Must Return to Orlando The obsession with Casey Anthony's whereabouts is about to end.Acquitted of killing her 2-year-old daughter, Caylee, Anthony vanished into the night after her July 17 release from jail. As she spent the next two weeks in hiding, people speculated that she was everywhere from California to the Bahamas But thanks to a judge's order, Anthony will return to Orlando as quickly as within the next three days. On Monday morning, Orange County Judge Stan Strickland signed amended court documents that will require Anthony to serve one year of supervised probation on her check fraud charges . "She should be reporting to probation in Orlando probably within 72 hours," Strickland said.Strickland sentenced Anthony last year on charges that she had stolen a friend's checkbook and forged several checks. On Thursday, he said he intended for Anthony to go to supervised probation upon her release from jail. Upon Anthony's release, the Department of Corrections officials misinterpreted Strickland's order as meaning that Casey Anthony had served her probation while still in jail.It is unclear where Anthony will stay when she returns to Orlando. Her attorney did not immediately return a call for comment.

– The worldwide media manhunt for Casey Anthony will soon be over—she'll be right back in Orlando within the next three days. The judge who sentenced Anthony on check fraud charges last year has amended documents so that she'll have to serve one year of supervised probation, reports the Orlando Sentinel. "We're in contact with Casey Anthony's attorneys to set up her first report visit," said a Department of Corrections spokeswoman. The judge gave the probation order after Anthony was accused of stealing a friend's checkbook and forging checks. But there was confusion about whether he originally intended for Anthony's probation to be fulfilled while she was imprisoned awaiting trial in the death of 2-year-old daughter Caylee. DOC officials misinterpreted the order and allowed her to walk free when she left prison on July 17, but the new paperwork changes that. Anthony's defense team will probably cite double jeopardy, and challenge the ruling. It's not clear where Anthony will stay while in Orlando.

this paper develops new modelling and estimation procedures for complex - valued time series . we derive the interpretation of such models , and efficient methods for their estimation based on sampled time series . complex - valued series are a useful representation of bivariate series , and arise in a significant number of important application areas , such as functional magnetic resonance imaging @xcite , doppler ultrasound signals of bloodflow @xcite , optical tomography @xcite , seismic readings @xcite , neural networks @xcite , meteorology and oceanography @xcite and blind source separation @xcite . we refer to section 1.9 in @xcite for a more extensive list . there have also been a number of recent advances in methodological statistics for the analysis of complex - valued vectors , as well as for time - series samples @xcite . a common need in applications is the ability to specify a simple parametric model for the signal structure , and then to estimate these parameters from a finite sample . however , approaches to inference for complex - valued series have mainly been non - parametric , and little focus has been placed on methods for efficient parametric inference . for reasons that will be come clear , our approach to parametric modelling will be in the frequency - domain . to this end , a main contribution of this paper is extending the whittle likelihood @xcite to complex - valued time series , addressing new ways to deal with finite sample effects in the process . ( top left ) trajectories from the global drifter program . ( top right ) trajectory of a north atlantic drifter i d # 44000 . ( bottom left ) velocities of this drifter over time in each cartesian direction . ( bottom right ) the estimated power spectrum of the complex - valued velocities for the first 40 days only.,title="fig:",scaledwidth=45.0% ] ( top left ) trajectories from the global drifter program . ( top right ) trajectory of a north atlantic drifter i d # 44000 . ( bottom left ) velocities of this drifter over time in each cartesian direction . ( bottom right ) the estimated power spectrum of the complex - valued velocities for the first 40 days only.,title="fig:",scaledwidth=47.0% ] + ( top left ) trajectories from the global drifter program . ( top right ) trajectory of a north atlantic drifter i d # 44000 . ( bottom left ) velocities of this drifter over time in each cartesian direction . ( bottom right ) the estimated power spectrum of the complex - valued velocities for the first 40 days only.,title="fig:",scaledwidth=47.0% ] ( top left ) trajectories from the global drifter program . ( top right ) trajectory of a north atlantic drifter i d # 44000 . ( bottom left ) velocities of this drifter over time in each cartesian direction . ( bottom right ) the estimated power spectrum of the complex - valued velocities for the first 40 days only.,title="fig:",scaledwidth=47.0% ] to show the relevance of our work , we plot measurements from a large array of freely - drifting oceanographic instruments , created and distributed by the global drifter program ( gdp , aoml.noaa.gov/phod/dac ) in the first panel of figure [ figintro ] . the gdp is a database of global circulation measurements important for our understanding of decadal to century - scale climate change . each series in this data set can be represented as a complex - valued series . for example , we show a 150-day trajectory from global drifter program i d # 44000 in the top right of figure [ figintro ] . the velocities corresponding to the eastward and northward displacements , together with the periodogram ( the magnitude square of the fourier transform ) of the complex - valued velocity for the first 40 days of these two velocity signals , are displayed on the bottom row of figure [ figintro ] . we have plotted the negative and positive frequency axes overlaid , and it is clear that certain features are only present on one side of the spectrum , indicating oscillatory behaviour with a preferred direction of spin . such structure is significantly easier to model in the frequency domain than in the time domain . the first key contribution of this paper is the creation of appropriate frequency - domain models for complex - valued time series like the surface drifter velocity records . the second key contribution is the development of an improved inference method . specifically , we practically and efficiently adapt whittle likelihood for real and complex - valued time series . for asymptotic understanding , well - established results have been the consequence of the initially derived theory , e.g. @xcite . for finite @xmath0 however , more subtle effects are known to be in evidence @xcite . most observed time series are nonstationary ( as in figure [ figintro ] ) , such that stationarity can only be reasonably assumed over small windows , for example by assuming local stationarity or segmenting the series . this motivates the development of parsimonious models , and indicates the need for bias - corrected estimation procedures for finite - length samples . to achieve accurate inference with small sample sizes , we here propose the use of the _ blurred _ whittle likelihood . this novel approach accounts for sampling effects such as leakage and aliasing , while maintaining the @xmath1 computational efficiency of the standard whittle likelihood . we prove consistency and discuss properties of our likelihood , and analyse performance through simulations against state - of - the - art time domain approximations @xcite . while our focus is on complex - valued series , the advantages of the blurred whittle likelihood are just as relevant for applications to real - valued series . in addition , we extend a number of related statistical procedures to complex - valued time series . we propose semi - parametric procedures for models that are misspecified at certain frequencies , relating this to @xcite . we construct a parametric test for impropriety , which tests for anisotropy if the time series track spatial positions . finally , we provide model choice criteria for selecting between nested models . at first glance , it may seem that formulating theory and methods for complex - valued time series is just a special case of the study of bivariate real - valued series . in this paper we will show that this is not the case . we introduce flexible models for complex - valued signal structure that incorporate the possibility of anisotropy or impropriety . a focus here is on the matrn process , a natural choice for modelling multiscale variability such as that seen in the surface drifter trajectories . we shall illustrate such concepts with practical examples . the paper is organised as follows . in section [ s : prelim ] we provide some necessary preliminaries for real- and complex - valued time series . in section [ s : models ] we introduce our models for cartesian and rotary structure in complex - valued time series . section [ s : whittle ] introduces the whittle likelihood for complex - valued time series and also the _ blurred _ likelihood which correctly accounts for finite - sample bias in both real- and complex - valued time series . we then prove consistency of the blurred whittle likelihood in section [ s : prop ] . in section [ s : implem ] we discuss semi - parametric inference , likelihood ratio tests and model choice . finally , in section [ s : simulations ] we demonstrate our modelling and inference procedures , including a detailed analysis of oceanographic flow and seismic data . concluding remarks can be found in section [ s : conclusions ] . readers only interested in developments for real - valued processes should only refer to sections [ prelim - real ] , [ whittle - real ] , [ whittle - taper ] , [ s : prop ] and [ ss : simulations1 ] . the sequence @xmath2 is defined from a corresponding zero - mean continuous - time gaussian process @xmath3 , by @xmath4 , where @xmath5 is the sampling period and @xmath6 . assuming that the process is second - order stationary , one may define the autocovariance sequence @xmath7 for @xmath8 , where @xmath9 denotes expectation . the power spectral density of @xmath2 forms a fourier pair with the autocovariance sequence : @xmath10 the angular frequency @xmath11 $ ] is given in radians . for a sample @xmath12 , a simple , but statistically inconsistent estimate of @xmath13 is the periodogram denoted @xmath14which is the squared absolute value of the discrete fourier transform ( dft ) defined as @xmath15.\ ] ] using the spectral representation theorem we can write @xmath16 in terms of orthogonal increments @xmath17 where @xmath18 . note that because @xmath16 is a discrete sequence , @xmath19 has already been aliased . thus there may be departures between @xmath13 and the continuous - time process spectral density , which we denote as @xmath20 . a direct consequence of equations and is that by calculating the dft from a finite sample size , we have automatically blurred " the spectral information , due to leakage and aliasing effects . leakage is associated with the truncation of the sequence @xmath16 over a finite time interval , whereas aliasing results from the discrete sampling of the continuous - time process to generate an infinite sequence ; both effects are a consequence of analysing a sample of a continuous - time process . as it does not account for these effects , the periodogram is considered a nave estimator of the continuous time process spectral density . the expected value of the periodogram is equal to the convolution of the true spectrum with the fejr kernel ( the magnitude - squared of the dirichlet kernel ) , which can badly bias spectral estimates ( e.g. @xcite ) . leakage effects are often tackled by using tapering ( e.g. @xcite ) which reduces bias and variance at each frequency , at the expense of increased correlation between neighbouring fourier frequencies ; we will discuss this trade - off in more detail in this paper . the issue of aliasing results in energy outside of the nyquist frequency ( the highest observable frequency , @xmath21 ) being folded back into the observable spectrum , which is often ignored when estimating spectra of continuous sampled processes @xcite . the classical approach to frequency - domain inference , the whittle likelihood , makes use of the periodogram and therefore relies on asymptotic behaviours for very large sample sizes to minimise bias effects . in section [ s : whittle ] , we propose a new modification of the whittle likelihood that directly incorporates finite sampling effects from both leakage and aliasing correctly , which can be used with either the periodogram or tapered spectral estimates . as is already done in my applications areas , it is often convenient to express bivariate time series as complex - valued . the real and imaginary parts often represent displacements or velocities in orthogonal spatial directions , and will be henceforth referred to as the _ cartesian components_. a more useful decomposition of the variability , however , is to separate the process into _ rotary components _ , that is , into contributions from positively - rotating and negatively - rotating complex exponentials . statistical understanding of complex - valued time series , in particular in the frequency domain , has been developed over the past 20 years ( see e.g. @xcite and @xcite ) . to form a complex - valued series , we start from a pair of real - valued sequences , @xmath22 and @xmath23 . these processes can be combined to form the complex - valued sequence @xmath24 via @xmath25 . we shall assume that @xmath22 and @xmath23 are jointly gaussian and zero mean , such that any collection of the processes at a number of sampled points are gaussian . therefore to fully characterise their properties we need to specify the joint covariance @xmath26 as well as @xmath27 and @xmath28 . if the process is stationary then we have @xmath29 and @xmath30 , as well as @xmath31 for the cross - covariance sequence ; the latter then forms a fourier pair with @xmath32 , as in equation . alternatively , in terms of the stationary complex - valued gaussian process @xmath24 , the process may be fully characterised by specifying the covariance and _ relation _ sequence @xmath33 @xmath34 , \nonumber\\ r_{zz}(\tau)&=&{\ensuremath{\operatorname{\mathbb{e}}}}\{z_tz_{t-\tau}\ } = s_{xx}(\tau)-s_{yy}(\tau)+i[s_{xy}(-\tau)+s_{xy}(\tau ) ] , \label{rzz}\end{aligned}\ ] ] with @xmath35 denoting the complex conjugate of @xmath36 . clearly specifying @xmath37 and @xmath33 for the complex - valued process is equivalent to specifying @xmath38 , @xmath39 , and @xmath40 for the bivariate real - valued process . it is directly apparent from equation that @xmath41 ( hermitian symmetry ) and @xmath42 ( symmetry ) . the spectrum and complementary spectrum are defined from @xmath37 and @xmath33 via a fourier transform @xmath43 where @xmath44 and @xmath45 . the spectrum and complementary spectrum together describe the second order properties of the fourier transform of the complex - valued process @xmath24 . we note that @xmath46 is _ not _ the relation sequence of the fourier - domain orthogonal increment process @xmath47 , but rather is the fourier transform of the relation sequence of @xmath36 . if the relation sequence , or the complementary spectrum , is zero everywhere then the process is said to be _ proper _ , and otherwise it is _ improper _ @xcite . a key motivation behind this paper is not to interpret complex - valued time series as bivariate real - valued time series , but instead as processes that have two complex - valued counter rotating components . this decomposes a process according to the direction of spin . specifically , we write @xmath48 , \label{eq : zpluszminus}\ ] ] where @xmath49 and @xmath50 are both _ analytic _ , that is , supported only on positive frequencies . under the assumption of stationarity , the spectra of the two rotary processes are given by @xmath51 and @xmath52 , while the cross - spectrum is @xmath53 ; all of these are defined only for @xmath54 , and vanish otherwise . the relationships between three different representations of a complex - valued process cartesian ( @xmath55 ) , complex ( @xmath56 ) and rotary ( @xmath57 ) are presented in table [ table : realcomplex ] . the derivations can be found in section [ sm : derivations ] of the appendix . note that relationships involving @xmath57 do not hold at frequency @xmath58 , as the energy at this frequency is divided between the two rotary components these specific relationships can also be found in the appendix . the rotary components are defined only for positive frequencies as they are analytic and hence equal to zero for negative frequencies . the relationships between the cartesian and complex / rotary representations are nontrivial , and highlight some of the differences between working with bivariate and complex - valued data . we will refer to table [ table : realcomplex ] in future sections to provide more intuition and simplify calculations . similar expressions relating the covariance ( and relation ) sequences of each representation can be found from table [ table : realcomplex ] using inverse fourier transforms . sometimes the decomposition is made slightly differently , such that @xmath59 is analytic and the second component is defined to be anti - analytic , i.e. have a spectrum only defined on negative frequencies . we prefer our representation , and consider it more natural as we then only need to specify a covariance structure between @xmath59 and @xmath60 , as the relation sequence is zero everywhere , in contrast to @xcite for example . at first the division in equation may seem artificial and opaque . one might argue that representing a bivariate time series as complex - valued is unnecessarily complicated , making the inclusion of _ two _ extra complex - valued processes seem yet more redundant . we shall see that splitting up a process into two components in this way is natural , as it divides the process into forward rotating and reverse rotating phasors , as is clear from equation . the rotary decomposition has been used as a modelling tool for many years and across many applications , as detailed in section 1.9 in @xcite . in this section we discuss key aspects of the specification of stochastic models for complex - valued time series , including the possibility of coherence between time series components . specifying rotary coherence is different from specifying cartesian coherence . as a practical example , we focus on models based on the matrn process . as real - world time series may be characterised by significant coherence between components , we must develop stochastic models that are capable of capturing such behaviour . a common way of defining covariance structure in bivariate series is in the time domain , but in this paper we do this in the frequency domain by modelling the _ frequency - domain coherency_. we represent the cross - spectrum between @xmath22 and @xmath23 as @xmath61 where @xmath62 is the _ coherency _ of @xmath22 and @xmath23 ; @xmath63 is the _ coherence _ , and @xmath64 is the _ group delay _ , quantifying whether @xmath22 or @xmath23 are leading or lagging in time at frequency - cycle @xmath65 . we refer to @xmath66 as the _ cartesian coherency_. the group delay and coherence must satisfy @xmath67 on account of the hermitian symmetry of @xmath32 . from a modelling standpoint , we may also regard equation as _ specifying _ the cartesian cross - spectrum for a given choice of the individual spectra @xmath13 and @xmath68 , together with a suitable choice of the coherency @xmath66 . it can be shown that choosing @xmath66 with @xmath69 and @xmath70 does indeed lead to a valid spectral matrix that is always non - negative definite . realistic functions specifying @xmath63 would include the logistic function @xmath71 as we note directly from equation that @xmath63 must be an even function . furthermore it is reasonable to have decaying polynomials such that @xmath72 , which will be the case in equation provided the highest - order polynomial coefficient is positive , i.e. @xmath73 . similarly , as @xmath64 is odd , we may propose the form @xmath74 the simplest choice for the orders @xmath75 and @xmath76 is @xmath77 , which imposes a simple structure of fixed correlation across all frequencies . note that while a constant phase is not valid , we may have @xmath78 , where @xmath79 is the signum function ; or we may have phase that is locally constant within particular frequency bands ( see @xcite ) . next we ask what constraint is imposed on the phase function @xmath64 if we require the time series to be proper . it follows from table [ table : realcomplex ] that we require @xmath80 _ and _ @xmath81 in order for the time series to be proper . for the second condition we require that _ at each _ positive frequency @xmath82 , either @xmath83 _ or _ @xmath84 and @xmath85 , such that @xmath22 and @xmath23 are strictly out of phase . " the latter possibility follows from the fact that a time series is zero - mean gaussian and proper if and only if it is _ circular _ ( i.e. a series whose properties are invariant under rotation ) , see @xcite . an example of such would be a deterministic time series which follows an exact circle , which corresponds to @xmath86 and @xmath87 . for spatially generated processes such as the oceanographic time series we shall study subsequently , propriety is found to be related to the condition of spatial isotropy , with impropriety in turn implying anisotropy . thus we can test for anisotropy in the spatial process that generates the sampled time series , and so if the complex - valued time series is generated from a spatial process , we to refer to propriety and isotropy interchangeably . alternatively one may employ a model which specifies the coherence between rotary components @xmath59 and @xmath60 . as we have chosen the two to be supported only on positive frequencies however , there can be no covariance between @xmath88 and @xmath89 . therefore in addition to specifying the variance of @xmath90 and @xmath91 , corresponding to specifying the rotary spectra , we only need to model their covariance at the same frequency . the _ rotary coherency _ @xcite is defined as @xmath92 where again @xmath93 . taking equation as a _ model _ for the rotary cross spectrum , we find he flexibility for @xmath94 to vary across frequencies particularly useful . in oceanographic data , for example , it is unlikely that clockwise and anti - clockwise oscillations will be correlated identically at all frequencies but at different frequencies we would expect a different mode of correlation , see e.g. @xcite . another desirable aspect of the rotary model specification is that we can account for the possibility of different slopes governing the spectral decay across positive and negative frequencies . as we shall see later such would be extremely challenging to incorporate into the model for @xmath22 and @xmath23 , but considerably easier to incorporate for the complex - valued rotary decomposition . as in the cartesian case , one may construct models for the coherence @xmath95 and group delay @xmath96 comparable to equations and , with the difference that these functions now only need to be supported over positive frequencies . if we desire to model proper complex - valued series , we see from table [ table : realcomplex ] that we require that @xmath97 for @xmath98 . thus , a proper complex - valued time series has no rotary coherency at non - zero frequencies , which is an important interpretation of propriety . as an aside , we point out that if one desires to model a _ non - zero - mean _ proper time series , we must additionally ensure that @xmath99 vanishes ; this is because @xmath100 only for @xmath101 . modelling the rotary coherency can be used to formulate a test for impropriety , as is detailed later in section [ impropriety ] . to illustrate the specification of a model with frequency - domain coherence , we will employ a particular type of random process that is in increasingly widespread use . the matrn process @xcite is a continuous stationary gaussian process that has received much attention in the spatial and spatiotemporal modelling literature . after carrying some theoretical extensions in the remainder of this section , we will also employ the matrn process in the applications of section [ s : simulations ] . the univariate matrn process is a three - parameter , stationary gaussian process with covariance given by @xmath102 where @xmath103 and @xmath104 is the modified bessel function of the second kind . the smoothness parameter @xmath105 defines the hausdorff dimension ( equal to max@xmath106 ) and the degree of differentiability of the process , the range parameter @xmath107 is a timescale parameter , where @xmath108 can be referred to as the correlation timescale , and @xmath109 defines the magnitude of the variability of the process . the matrn is a useful process in time series analysis , as the limiting behaviour over short timescales ( or as @xmath110 ) is like nonstationary fractional brownian motion , whereas the limiting behaviour over long timescales ( or as @xmath111 ) is white noise the matrn hence provides a continuum between these two regimes over different timescales . we can therefore view the process as truly multiscale . the process has the potential to capture complicated structure while simultaneously being parsimonious , yielding useful modelling potential for structured processes with which we wish to infer physically meaningful parameters from relatively few observations . there has been much interest in constructing valid multivariate matrn processes in the spatial statistics literature . in particular , @xcite and @xcite have constructed multivariate matrn processes such that all marginal covariances and cross - covariances are themselves also of matrn type , i.e. for dimensions @xmath112 and @xmath113 ( where @xmath114 ) of the @xmath115-variate process @xmath116 @xmath117 where @xmath118 is the correlation coefficient between @xmath112 and @xmath113 ( which is trivially set to 1 if @xmath119 ) , @xmath120 and @xmath121 is the univariate matern covariance function defined in equation . @xcite specifies necessary and sufficient conditions for the bivariate matrn process ( @xmath122 ) to have cross - covariances that are of matrn type and for the covariance matrix to be nonnegative definite . in this paper , however , we choose to specify the cross - covariance structure in the frequency domain . our rationale for this choice is twofold . first , for the oceanography application we study , it is easier to specify the covariance of the flow process in terms of specially chosen complex - valued processes from physical considerations . second , it is very easy to check whether a specified choice corresponds to a valid covariance ( we simply require @xmath123 in equation ) , unlike the torturous calculations sometimes necessary in the time domain . the spectrum of the continuous - time matrn process has a succinct and interpretable representation : @xmath124 where @xmath20 indicates the spectral density of the continuous - time process . this relates to the aliased spectral density of a sequence @xmath2as defined in equation via the relationship @xmath125 for @xmath126 $ ] . we can specify that @xmath59 and @xmath60 are matrn processes with spectra that follow the form given in equation , for @xmath127 . we denote these parameters as @xmath128 and @xmath129 , which are permitted to differ between the processes . if we specify a model for the cross - spectra using equation , then the overall process is valid as long as @xmath123 . by valid " we mean it possesses an invertible covariance / spectral matrix , but not necessarily a cross - covariance / cross - spectrum that is also matrn , _ unlike _ the definition of @xcite . in this sense our specification is more general , particularly as we can propose frequency - dependent coherence . if we do wish to formulate cross - spectra that are of matrn form , we can set @xmath130 and @xmath94 as real - valued and constant across frequency , but still allow @xmath131 and @xmath132 . it is easy to show using equation , that this specifies a valid matrn as per the @xcite definition , however for comparison , we verify that this parameterisation also meets the conditions required by @xcite , in section [ sm : matern ] of the appendix . finally , it is interesting to discuss the matrn family in the context of a transformation framework , which we will make use of later in the applications . we define the deformation operator @xmath133 , where @xmath75 is an amplitude scaling transformation and @xmath134 is a temporal dilation or compression . we take @xmath135 , @xmath136 , assuming that @xmath137 and @xmath138 are independent realisations of the same stochastic process . this deforms the original stochastic processes and also introduces correlations . it follows that @xmath139 , and we see that the processes remain jointly stationary , but stretched or compressed in time by the factor @xmath134 . if we look at the cross - spectrum then it transpires that it takes the form @xmath140 we find that if @xmath141 takes a matrn form , then so does @xmath142 , but with altered parameters . both @xmath143 and @xmath144 change from such deformations but not @xmath145 . this indicates how a jointly matrn process can be generated by a simple transformation of an original matrn . alternatively we may combine a matrn process in each of the two cartesian or rotary components , with the parametric specification of coherency discussed in sections 3.1 and 3.2 . choosing the rotary representation , and setting the damping and slope parameters of the positive and negative rotary components to be equal , the form of the spectral matrix becomes @xmath146 where the coherence function @xmath94 remains to be specified . this type of bivariate model would regulate _ the same _ scaling behaviour between @xmath59 and @xmath60 , but the energy of each process being individually regulated by @xmath147 and @xmath148 . we use this model to capture both isotropic and anisotropic structure in oceanographic flow processes in section [ ss : simulations2 ] . the usefulness of the matrn family is that multiscale behaviour is achievable from one single family . a subtle issue , however , is the relationship between the rotary and cartesian decompositions . specifying two matrns with unequal slope and/or range parameters in one representation will , in general , force the other to posses a mixture of matrns ; this can be inferred from the identities in table [ table : realcomplex ] . in general , a matrn specified in @xmath59 and @xmath60 only specifies a matrn in @xmath22 and @xmath23 if @xmath130 and @xmath149 , and if @xmath150 and @xmath151 are constant across frequencies such that the cross - spectra are coincidentally of matrn form even when @xmath152 or @xmath131 . ] ; the reverse it also true . in such cases the cross - spectra @xmath32 and @xmath142 are in general complex - valued and out - of - phase . this means that a simple model in one decomposition does not lead to a simple model in the other , and the practitioner must therefore understand the data and the processes driving the data to find the simplest decomposition in which to model . in this section we turn to the problem of estimating the parameters of a chosen model from observations . maximum likelihood is the preferred approach but has two drawbacks . first , its large computational cost renders it unwieldy to apply in practice ; this is due to the computational cost associated with inverting the full time - domain covariance matrix . second , we wish to parameterise the structure in terms of properties of @xmath59 and @xmath60 , which is not conveniently implemented in the time - domain . the method we shall choose , however , will closely _ approximate _ the time - domain log - likelihood , preserving its desirable qualities . henceforth we let @xmath22 and @xmath23 indicate length @xmath0 samples of the corresponding random processes arranged as column vectors . in the univariate case of a sample @xmath22 from a zero - mean real - valued gaussian process , after choosing a particular parametric model characterised by a vector of parameters @xmath153 , the time domain log - likelihood can be written as @xmath154 where we note that the subscript @xmath155 " is a label standing for time " , the superscript @xmath156 " denotes the transpose , and the superscript @xmath157 " is the matrix inverse . here @xmath158 is an @xmath159 theoretical covariance matrix that @xmath22 would take , under the assumption that it is a sample drawn from the proposed model . @xmath160 denotes the determinant of @xmath161 . to find the log - likelihood appropriate for the bivariate process consisting of @xmath22 and @xmath23 we concatenate the two time domain samples into a single vector : @xmath162 . the theoretical covariance matrix for this vector under the assumed model is denoted by @xmath163 . the log - likelihood of the vector @xmath164 can then be written as @xmath165 in direct parallel with equation . the best choice of parameters @xmath153 for our chosen model to characterise the observed data is found by maximising the likelihood function @xmath166 because the time - domain maximum likelihood is known to have optimal properties , any other estimator will be compared with the properties of this quantity . a standard technique to approximating equation is in the frequency domain , from the seminal work of @xcite , which results in vastly increased computational speed . this approach approximates @xmath167 using a fourier representation , and and utilises the special properties of toeplitz matrices . for a single real - valued time series the whittle likelihood is given by @xmath168\\&=-\sum_{\omega\in \omega } \left[\log \left\{\widetilde s_{xx}(\omega;\bm{\theta } ) \right\}+\frac{\hat s_{xx}(\omega)}{\widetilde s_{xx}(\omega;\bm\theta)}\right ] , \label{whittle_likelihood2}\end{aligned}\ ] ] where the subscript @xmath169 stands for whittle " and the superscript @xmath170 " denotes the hermitian transpose . @xmath171 is the parametric form of the theoretical spectrum of the continuous - time process as a function of frequency , and @xmath172 is the set of discrete fourier frequencies : @xmath173 . the simplification of equation follows as @xmath171 and @xmath174 are scalar - valued at each frequency ; however , we keep the form of equation for comparison with later models in which the spectrum will be matrix - valued at each frequency . note that @xmath172 may be chosen to be smaller that the full range of fourier frequencies , in which case the whittle likelihood can be considered as a semi - parametric fitting procedure ( see section [ semipm ] for more discussion ) . the whittle likelihood _ approximates _ the time - domain likelihood when @xmath175 $ ] , i.e. @xmath176 , and this statement can be made precise @xcite . however its computational cost is @xmath177 versus @xmath178 for the time - domain likelihood , a vast increase in speed that renders it more suitable for applications . there have been recent advances however in constructing @xmath177 time - domain approximations to maximum likelihood ( see @xcite ) and we compare performance in a simulation study in section [ ss : simulations2 ] . the whittle likelihood is based on the periodogram spectral estimate @xmath179 , which is known to be a problematic quantity . the periodogram is in general an inconsistent and biased measure of the continuous time process spectral density , due to the blurring caused by leakage and aliasing effects . it is important to note that the desirable properties of the whittle likelihood rely on the _ asymptotic _ behaviour of the periodogram for very large sample sizes . in order to prevent problems with the periodogram for finite sample sizes from adversely affecting our inference process , we define an alternative likelihood function to @xmath180 and @xmath181 based on @xmath174 , written as @xmath182 , \\ \nonumber \overline{s}_{xx}(\omega;\bm{\theta})&=&\int_{-\pi/\delta}^{\pi/\delta } { s}_{xx}(\omega';\bm{\theta}){\cal f}_{n,\delta}\left(\omega'-\omega\right)\;d\omega ' , \quad { \cal f}_{n,\delta}(\omega)=\frac{\delta}{2\pi n}\frac{\sin^2 ( n \omega\delta/2)}{\sin^2(\omega\delta/2)},\end{aligned}\ ] ] where the subscript @xmath183 " stands for frequency . " here @xmath184 is a version of the theoretical modelled spectrum that has been _ blurred _ by a convolution with the fejr kernel @xmath185 . it can readily be shown that if @xmath22 is drawn from a process with a given theoretical spectrum , the expected value of its periodogram @xmath186 will blur the theoretical spectrum in precisely the same way . therefore the bias in the estimation process caused by leakage and aliasing arising from finite sample effects has now been correctly accounted for . we call this the _ blurred whittle likelihood _ and prove consistency of estimators in section [ s : prop ] , as well as document its performance in a monte carlo study in section [ ss : simulations1 ] . the usual form of the whittle likelihood can be computed efficiently by using the fast fourier transform ( fft ) to calculate the dft , which is an @xmath1 operation . the blurred whittle likelihood however , is slightly more complicated to compute as @xmath187 must now be calculated . the best way to do this is by working with the fourier pair of the blurred theoretical spectrum @xmath188 , which is the expected biased sampled autocovariance sequence of length @xmath189 , denoted @xmath190 for @xmath191 , @xmath192 observe that the truncation to finite length has the effect of multiplying the true autocovariance sequence with the triangle kernel . in fact , both aliasing and leakage effects are automatically accounted for in equation ; the effect of _ aliasing _ is accounting for by sampling the theoretical autocovariance function at discrete times , while the effect of _ leakage _ due to the truncation of the sample to finite length is accounted for by the triangle kernel . by forming the blurred and aliased spectrum @xmath188 in this way from a _ time domain _ multiplication , we avoid an expensive summation over the aliased frequencies , and the algorithm may still be performed in @xmath177 operations . note that if the closed form of the autocovariance sequence is unknown , then we can inverse fourier transform the modelled spectrum of the process to approximate the autocovariance sequence numerically ( see equation ) . subsequently we would take the fourier transform of this sequence , multiplied with the triangle kernel ( as in equation ) , to recover an estimate of @xmath187 , still in @xmath1 operations . as an aside , we note that computing the whittle likelihood with the aliased , but not blurred , spectrum @xmath193defined in equation can be complicated , as this seldom has an analytic form and must be instead approximated by either arithmetically wrapping in contributions from frequencies higher than the nyquist , or via an approximation to the fourier transform in equation . this is in contrast to the blurred whittle likelihood , where the blurred spectrum can be computed exactly in one operation , as in equation . it is therefore easier to incorporate both leakage and aliasing effects together , rather than separately . so far we have encountered the time - domain likelihood , the standard whittle likelihood , and the blurred whittle likelihood . there is a fourth possible likelihood that could be defined by extending the whittle likelihood to tapered discrete fourier transforms @xcite . this corresponds to replacing the direct spectral estimator formed from @xmath174 in equation with one using the taper @xmath194 @xmath195 where @xmath196 is real - valued . setting @xmath197 recovers the periodogram estimate of equation . the tapered fourier transform is used to reduce bias in non - parametric estimation from leakage @xcite . in the parametric setting we take @xmath198.\ ] ] @xcite demonstrated that for certain discrete processes it is beneficial to use this estimator , rather than the standard whittle likelihood , for parameter estimation particular when the spectrum exhibits a large dynamic range . nevertheless , tapering will _ not _ remove all leakage effects , and the issue of aliasing for continuous sampled processes remains . we therefore define a fifth possible type of likelihood , which accounts for finite sampling effects from tapering @xmath199 , \\ \nonumber \overline{s}_{xx}(\omega;h,\bm{\theta})&=&\int_{-\pi/\delta}^{\pi/\delta } { s}_{xx}(\omega';\bm{\theta}){\cal h}_{n,\delta}\left(\omega'-\omega\right)\;d\omega ' , \quad { \cal h}_{n,\delta}(\omega)=\delta \left|\sum_{t=1}^n h_t e^{-i\omega t \delta } \right|^2.\end{aligned}\ ] ] we call this the _ tapered blurred whittle likelihood _ , and it can be computed using a similar @xmath1 calculation to equation to find @xmath200 @xmath201 note that the time - domain kernel @xmath202 must be pre - computed ( unless it has an analytic form ) which requires @xmath203 operations , but this can be stored for each taper and data - length @xmath0 , and does not have to be recomputed each time when performing numerical optimisation . with the modifications to the whittle likelihood we have proposed , the practitioner is free to select between a tapered or periodogram spectral estimate in the same way as before , but can now account for finite sample bias effects by using our methods . both the blurred tapered and blurred periodogram likelihoods have advantages and disadvantages . tapering reduces broadband leakage , but increases variance ( by effectively throwing away statistical information ) and also increases correlations between local frequencies . the periodogram may exhibit greater global bias and correlation with other frequencies , on account of the implicit convolution with the fejr kernel ; the magnitude of this effect depends on the degree of dynamic range of the observed process in frequency . we explore the comparison between these various methods , and demonstrate the importance of blurring the likelihood , through monte carlo simulations in section [ ss : simulations1 ] . in the previous section , modified versions of the whittle likelihood appropriate for a single real - valued time series were developed . next we construct the whittle likelihood for complex - valued time series . we start from the bivariate whittle likelihood @xcite and then reformulate this for rotary ( @xmath57 ) and complex ( @xmath56 ) components using the relationships given in section [ prelim - complex ] . while the whittle likelihood is normally derived with continuous - time spectra @xmath204 ( see equation ) , for notational simplicity in this subsection we formulate in terms of aliased spectra for sampled sequences , denoted @xmath13 , as defined in equation ; the representations however do not change for continuous - time spectra . we first define the cartesian spectral matrix and the cartesian fourier transform vector as @xmath205 using these definitions , the standard bivariate likelihood is @xcite @xmath206,\ ] ] where again @xmath172 is the set of discrete fourier frequencies : @xmath173 . we note that this likelihood is the bivariate form of equation , and it approximates the bivariate likelihood of @xmath181 given in equation . the bivariate likelihood can be equivalently expressed in term of the rotary components , as will now be shown . we start by defining the rotary spectral matrix and rotary fourier vector : @xmath207 the complex - valued length-@xmath0 sequences @xmath208 and @xmath209 are defined implicitly by equation for @xmath210 . there is a simple linear relationship between @xmath211 and @xmath212 @xmath213 as can be seen directly from @xmath214 together with equation . by inverting equation we have that @xmath215 we then substitute equation into equation @xmath216.\label{eq : complexsub}\ ] ] by expanding and rearranging , and using @xmath217 at @xmath127 , we see that @xmath218 which from table [ table : realcomplex ] is simply equal to @xmath219 , meaning that equation simplifies to @xmath220 , \label{whittle_rotary}\ ] ] where @xmath221 denotes equality up to an additive constant . the whittle likelihood for complex - valued time series , given by equation , is therefore equivalent to the bivariate likelihood of equation . the blurred , tapered , and blurred / tapered versions of the whittle likelihood for complex - valued series can similarly be computed by inserting the appropriately modified versions of the rotary spectral matrix , and/or the fourier transform vector , into equation . for example , if we wish to retain the blurred whittle likelihood analysis for complex - valued time series we evaluate @xmath222 , \label{complex_whittle_2 } \\ \nonumber \overline{s}_\pm(\omega;\bm{\theta})&=&\int_{-\pi/\delta}^{\pi/\delta}s_\pm(\omega';\bm{\theta}){\cal f}_n\left(\omega'-\omega\right)\;d\omega',\end{aligned}\ ] ] and similarly for tapered versions . as discussed in sections 4.1 and 4.2 , these can all be computed in @xmath223 operations . one detail regarding the whittle likelihood in terms of its rotary representation is that frequency @xmath58 can not be included in the range of estimation , owing to complications in defining the rotary spectra for zero frequency , see section a in the appendix . this is usually not a restrictive requirement , as in practice the time series is often differenced or has had its mean removed , such that the zero - frequency content of the time series is lost in any case , and there is no value in including this in the likelihood summation . if this is not the case however , and the frequency content of the signal at @xmath58 is appreciable , then the whittle likelihood can be represented in terms of @xmath224 and @xmath46 , which is of identical form to equation but can include @xmath58 . we note that for proper time series , when @xmath225 , this form of likelihood has the simple form @xmath226,\ ] ] where this time @xmath172 is the set of positive and negative discrete fourier frequencies , which is the length @xmath0 sequence @xmath227 . observe that the likelihood for a proper complex - valued time series has the same form as that for a real - valued univariate time series , see for example equation . it is known that standard whittle likelihood provides a consistent estimator of the spectrum @xcite . in this section , we establish consistency and related properties of the blurred whittle likelihood . the main difficulty in the proof is that , although the blurred whittle likelihood accounts for the bias of the periodogram , there is still present the broadband correlation between frequencies . this is what prevents the blurred whittle likelihood being exactly equal to the time - domain maximum likelihood for gaussian data . to establish consistency , we need to bound the asymptotic behaviour of this correlation . the statement is provided below in theorem 1 , with the proof provided in the appendix ( section [ sm : consistency ] ) . the proof is composed of three propositions which provide bounds , in turn , for the covariance of the dft , the variance of linear combinations of the periodogram , and finally the score and hessian of the blurred whittle likelihood . together these establish that the blurred whittle likelihood is a consistent estimator converging with probability at rate @xmath228 . we prove consistency for real - valued series , but the result naturally extends to complex - valued series also . this is because the fourier transform is complex - proper , even if the process itself is not , as long the process is stationary . this result requires that the spectrum , @xmath13 , is bounded from above and below , and that the blurred whittle likelihood , @xmath229 , is twice differentiable in @xmath153 . standard theory shows that the standard whittle likelihood approach is consistent with a @xmath230 rate if the spectrum is twice differentiable in @xmath65 and bounded below and above by a non - zero constant ( see @xcite ) . while the rate of convergence we prove is somewhat slower than that for the standard whittle likelihood , our method of proof requires weaker assumptions , as it does _ not _ require the assumption that the spectrum is differentiable in @xmath65 , and is near constant over widths of the fejer kernel . in practice , we find the benefits in bias reduction more than make up for the slower guaranteed rate of convergence . furthermore , we can see that the variances of the standard and blurred whittle estimators will behave similarly asymptotically , as sums of weighted periodograms will behave similarly whether weighted by quantities involving @xmath231 or @xmath13 . assume that the sequence @xmath2 is a zero - mean second - order stationary discrete process where @xmath184 , defined in equation , is twice differentiable in @xmath232 . assume that the spectral density of @xmath16 is bounded above by the finite value @xmath233 and below by the non - zero value @xmath234 . then the estimator @xmath235 for a sample @xmath12 , with @xmath229 being the blurred whittle likelihood defined in equation , satisfies @xmath236 we may conclude from theorem 1 that @xmath237 is a consistent estimator . note that for simplicity , and without loss of generality , we set @xmath238 in this section . having established consistency , we can use this to obtain variance estimates of the blurred whittle estimators . from equations , and in the appendix we see that @xmath239 where the matrix @xmath240 is defined entrywise by @xmath241 . the matrix @xmath240 can be approximated numerically , if the analytic form is not known by evaluating the hessian at @xmath237 . the remaining term , @xmath242 , is the likelihood score , and to estimate its variance we substitute from equation , noting that @xmath243 , and then express the partial derivative in each element of @xmath153 separately , to obtain @xmath244 where we have defined @xmath245 in deriving this expression we have made use of the fact that the @xmath246 term is deterministic and therefore does not contribute to the variance . as we have established consistency for @xmath237 we can now use the invariance principle to construct an estimator of @xmath247 we find that because @xmath237 is consistent we first take @xmath248 , and then to estimate the covariance of the periodogram we approximate the integral @xmath249 where @xmath250 is the dirichlet kernel ( see equation of the appendix ) . this provides estimates of the variance of the estimators . normality of @xmath237 follows because proposition 3 in the supplementary material shows that @xmath251 converges in probability to a positive constant , and @xmath252 is a gaussian quadratic form where the diagonalised representation does not put too much mass at any individual variate ; thus the sum will be a gaussian random variable . to further investigate what controls the variance of the estimators , we explore how the score behaves . the score is zero mean ( for any finite @xmath0 ) , and the variance ( as derived in equation of the appendix ) can be bounded by @xmath253 where @xmath254 and @xmath255 are upper bounds on the spectrum and the partial derivative of the blurred spectrum respectively , and @xmath256 is a lower bound on the blurred spectrum . the significance of equation is that the magnitude of the variance of the score is controlled by the dynamic range of the spectrum . a high dynamic range increases the value of the first ratio in the bound @xmath257 . this advocates differencing a sampled process with steep spectral slopes , as reducing this ratio will reduce the variance of the estimators , taking care to omit the zero frequency from the fit . this is consistent with numerical simulations performed in @xcite , where the whittle likelihood was found to perform poorly with fractionally differenced processes that were more smooth . indeed , we will demonstrate the effectiveness of fitting to the differenced process , if the process itself has a high dynamic range , with a numerical example in section [ ss : simulations1 ] . in this section we discuss several issues that arise in applying the inference method developed in the previous sections to complex - valued time series . as discussed in section [ whittle - real ] , the whittle likelihood for real and complex - valued time series can be performed over a reduced range of frequencies @xmath172 , such that inference is semi - parametric . we note work by @xcite and related papers by this author , in which frequency - domain inference is performed semi - parametrically . in contrast to our work , the @xcite approach is aimed at inferring long - memory processes such as fractional brownian motion and there is no bias correction performed in the whittle likelihood . we propose using semi - parametric inference for different reasons . primarily , frequencies can be omitted from the likelihood when the chosen model is only correctly specified within a certain range of frequencies . for example , in @xcite , the movement of surface drifter pairs exhibit different spectral slopes for certain ranges of frequencies . if we are only interested in inferring parameters of one of the slopes , for example , then this can be performed semi - parametrically by constraining @xmath172 accordingly . a second use of semi - parametric inference is that high frequencies can be omitted to account for sampling bias such as measurement uncertainty , which will contaminate high frequencies the most . we note however , that without a full model for the spectrum at all frequencies , then not all blurring and aliasing effects can be incorporated into the blurred whittle likelihood , although this was found to have limited effect in the practical examples studied in section [ s : simulations ] . care should be taken if the omitted frequencies have high spectral energy , as unknown leakage and aliasing effects could bias estimation . in sections [ prelim - corr ] and [ prelim - rotary ] we defined the coherence between components of a complex - valued time series , in particular , between the rotary components @xmath59 and @xmath60 . we may wish to test a proposed model for coherence against the simpler scenario where @xmath97 for all @xmath65 . this hypothesis corresponds to there being no relationship between the positive rotating and negative rotating phasors . we note from table [ table : realcomplex ] that this hypothesis is _ not _ equivalent to @xmath258 ; rather , a process with zero rotary cross - spectra , @xmath97 , is equivalent to a proper process , @xmath225 , for @xmath127 . this is a deliberate and convenient consequence of the way we have constructed @xmath59 and @xmath60 to _ both _ be analytic . testing for impropriety in the time domain is then equivalent to testing for a non - zero cross - spectrum between rotary components in the frequency domain . there are many tests for impropriety using data sets of multiple replicates of complex - valued vectors , see for example @xcite , @xcite and @xcite . we note that these are _ non - parametric tests _ using replicated complex - valued vectors . here , by contrast , we have a simple _ parametric _ time series model suitable for a _ single time series _ , and will derive a test statistic for this scenario . for example , we have proposed to study the matrn model in section [ s : matern ] , and can estimate suitable parameters for @xmath144 , @xmath145 and @xmath143 by using the whittle likelihood , which can be permitted to differ across the cartesian or rotary components as discussed . we can also estimate the coherence structure by specifying a model for @xmath150 and @xmath151 . we may however prefer to use the simpler model where @xmath97 and we can make use of the parametric model in combination with the whittle likelihood for complex - valued series to perform a likelihood ratio test to check for evidence if @xmath259 ( in equation ) such that @xmath260 . specifically , this is done by computing the likelihood ratio statistic @xmath261 where @xmath262 includes non - zero estimates for the coherency @xmath263 , while for @xmath264 , @xmath265 for all @xmath65 . the exact type of whittle likelihood used in equation ( tapered / periodogram or standard / blurred ) can be selected from section [ s : whittle ] . if we use the time domain bivariate likelihood ( see equation ) in equation , the likelihood ratio statistic @xmath266 is asymptotically distributed according to a @xmath267 distribution with degrees of freedom equal to the number of extra parameters @xmath115 in the alternative hypothesis versus the null . this follows from standard likelihood theory . in the appendix ( section [ sm : ht ] ) , we prove that the whittle likelihood for complex - valued series does yield a likelihood ratio statistic with a @xmath267 distribution , for special cases which include the practical example studied later in section [ ss : simulations2 ] . for the blurred whittle likelihood , the asymptotic properties of @xmath266 are more subtle , and care must be taken when the dynamic range of the spectrum is large . for standard processes , or after suitable differencing to lower the dynamic range , it is reasonable however to assume a @xmath267 distribution , as discussed in section [ sm : ht ] . we note that in the case of the coherency structure proposed in equations and , the degrees of freedom @xmath268 , which in the special case of a constant coefficient across frequencies with no group delay the number of degrees of freedom becomes @xmath269 . once the appropriate alternate model has been chosen , we can conduct hypothesis tests against the @xmath267 distribution to test for evidence of impropriety , and if multiple series are available , the user can contrast findings with non - parametric methods . we investigate this test for impropriety with a practical example in section [ ss : simulations2 ] . in many practical scenarios , the most appropriate choice for a model , and the corresponding number of parameters , is unknown _ a priori_. when it is possible to define a model such that possible candidate models are _ nested_that is , with simpler models being recovered from a more complete model by setting certain parameters to constants then it is possible to apply the method of _ model choice_. as an example , for a range of arma(p , q ) , processes , the akaike information criterion ( aic ) can be used to find the most appropriate choice of @xmath115 and @xmath270 . similarly , model choice can be used to select between a matrn and fractional brownian motion as the spectrum of fractional brownian motion is nested functionally ( but not formally ) inside that of a matrn ( by setting @xmath271 in equation ) . model choice can also be used to check if certain parameter values are correctly known _ a priori _ , such as the slope parameter @xmath145 in the matrn process , which is assumed for physical reasons to be a fixed known value for certain oceanographic time series ( as in @xcite ) . the aic can be closely approximated in the frequency domain using the whittle likelihood . this is done by using the whittle likelihood to approximate the time - domain likelihood and combining this with a model penalisation parameter as in @xcite : @xmath272 where @xmath115 is the number of parameters in the model . the model with the smallest aic value is then selected . for small sample sizes , it is often recommended to use a correction to the aic known as the aicc , which for complex - valued time series is given by @xmath273 which converges to the aic for large sample sizes . the correction uses @xmath274 ( rather than @xmath0 as would be done for real - valued time series ) as there are @xmath274 degrees of freedom in a length @xmath0 complex - valued time series . in the case of semi - parametric estimation , equation should not be used , as the sample - size correction needs to take account of degrees of freedom in the data not used in the estimation . we instead replace @xmath0 by @xmath275 in equation , which is the number of fourier frequencies used in the frequency range @xmath172 . when a tapered spectral estimate is used in whittle likelihood estimation , then the degrees of freedom are further reduced by the correlation induced in neighbouring fourier frequencies by the taper . this loss of resolution is also known as narrowband blurring , in contrast to the broadband blurring which is attributed to the leakage of the fejr kernel in the periodogram for example . without tapering , nominally each fourier coefficient , spaced @xmath276 apart , are uncorrelated ; however , with tapering , coefficients spaced @xmath277 are approximately uncorrelated , where @xmath278 is some constant reflecting the implicit bandwidth of frequency - domain smoothing . we must then further reduce @xmath275 by a factor of @xmath279 in the aicc , which can be computed by fourier transforming the taper onto a fine grid and then finding the frequency width where the transformed sequence is only correlated below some threshold ( such as 0.05 ) . in this section we present several real - world examples that apply the modelling and inference methods we have developed for complex - valued time series , as well as a monte carlo study to investigate the performance of the blurred whittle likelihood for simulated data . all data and matlab^^ code used to generate the results in this section can be found at www.ucl.ac.uk/statistics/research/spg/software , along with accompanying documentation , including a technical description of how the numerical simulation in section [ ss : simulations2 ] was performed . the numerical simulation can also be reproduced using the software available at jeffreyearly.com / numerical - models/. in section [ s : whittle ] , we presented several frequency - domain approximations to the standard time - domain maximum likelihood , and advocated the use of the blurred whittle likelihood ( @xmath280 in equation ) or the tapered blurred whittle likelihood ( @xmath281 in equation ) . these methods adjust for bias from leakage and aliasing , while maintaining the @xmath1 efficiency of the standard whittle likelihood . in this section we investigate the effectiveness of blurring the whittle likelihood in a monte carlo study using data from a real - valued matrn process , and then study the parameter estimates for each type of likelihood . recalling the motivating example in the introduction , we set our parameters to representative values for a surface drifter trajectory ( @xmath282 in equation ) which would be a good fit to the time - windowed spectra displayed in figure [ figintro ] , excluding the two peaks representing other oscillatory oceanographic processes . table [ table : mc2 ] displays the results of our monte carlo study with @xmath283 where we have averaged over 10,000 repeats to remove sampling variability yielding small standard errors of the performance metrics ( the standard error of the bias is equal to the standard deviation divided by 100 ) . note that we include results for two tapers : a discrete prolate spheroidal sequence taper ( of order zero , see @xcite ) and a full cosine taper @xcite . the optimisation is performed in matlab^^ using ` fminsearch ` and uses identical settings for all likelihoods , where initial values for the slope and amplitude are found by performing least squares on the spectral slope , with the initial guess for the damping parameter @xmath143 set to equal 10 times the rayleigh frequency , such that it is non - zero . the time - domain estimator marginally outperforms the blurred whittle methods , as expected from the optimal properties of the maximum likelihood estimator , but at a considerable computational expense the optimisation is two orders of magnitude slower than the whittle likelihood . for large data sets , such as that collected from the global drifter program , this burden is significant when computing across many million data points over rolling windows of time . in addition , for complex - valued time series , we may wish to specify rotary models in the frequency domain , which are not easy to formulate in the time - domain . of the whittle estimators , the blurred versions ( both periodogram and tapered ) perform significantly better than the standard form , both in terms of bias and root mean square error ( rmse ) . this is due to accounting for both aliasing and leakage effects , though the degree to which each of these effects matter will depend on the process and its dynamic range . the blurred likelihood using the periodogram returns biases and errors that are extremely close to that of maximum likelihood , at a fraction of the computational cost . the biases and errors may be found to be relatively larger with process with a higher dynamic range , but in such cases we find good results by differencing the process , and fitting this differenced process to the spectrum of the _ first difference _ of a sampled matrn process ( see the discussion of section [ s : prop ] ) . the additional computational cost of blurring requiring a second fourier transform is very small compared to the standard approach , and in this experiment it is preferable to use the periodogram rather than tapered spectral estimates . there have been recent developments in proposing @xmath1 approximations to maximum likelihood in the time domain made in @xcite ( see also @xcite and @xcite ) . these methods use hutchinson trace estimators and circulant embedding , thus removing the need to calculate a matrix inverse or determinant . we contrast our approaches here using the matlab package scalagauss " supplied by those authors at http://press3.mcs.anl.gov / scala - gauss / software/. we use the parameters selected in their example code for a matrn process , which only estimates the damping parameter , and assumes the slope parameter is known , and the amplitude parameter is known up to a proportion of the damping parameter . the parameters used , when transformed into the form of equation [ e : maternacvs ] , are @xmath284 and @xmath285 . as the slope parameter is very high with respect to the damping parameter , we fit the blurred whittle likelihood to the differenced process for better resolution . we perform 10,000 repeats and report the results in table [ table : mc3 ] . the method of @xcite returns estimation errors that are only slightly superior to those for the blurred whittle likelihood , however , this method requires an order of magnitude more processing time than the frequency - domain method . it should also be pointed out that the @xcite method is numerically far more complicated than the blurred whittle likelihood : whereas our method can be implemented in around 10 lines of code , the circulant embedding method requires several hundred , and also requires generating random numbers for the hutchinson trace estimators . furthermore , the online code provided in the scalagauss package only estimates one matrn parameter , it is not clear how easily the code can be generalised to estimate all 3 matrn parameters , as we have performed in the previous experiment in table [ table : mc2 ] . to speed up the @xcite method , we have included results with a faster version which uses only 1 hutchinson trace estimator ( as opposed to the 50 used in the example code ) , but this method is still slower than the blurred likelihood and now yields slightly worse estimation accuracy . overall , as with table [ table : mc2 ] , the reported biases are very small compared to the standard deviations ( where the standard error of the bias is the standard deviation divided by 100 ) . therefore no significance should be placed on the ordering of estimators in terms of bias , other than the poor performance of the standard whittle likelihood . this type of matrn process produces time series that appear nonstationary , and as documented by @xcite , standard whittle likelihood performs poorly in such scenarios unless tapering is used , as can also be seen in table [ table : mc3 ] . with the blurred likelihood however , the poor properties of the periodogram are corrected , and we see that there is no advantage to be gained by using the tapered spectral estimates . in this section we show the advantages of modelling bivariate processes in terms of their rotary decomposition . specifically we track the spatial trajectories of particles over time from two sets of numerical experiments , snapshots of which are displayed in figure [ figvorticities ] . here trajectories of particles are computed from the time - varying velocity fields associated with quasi - steady state forced - dissipative two - dimensional turbulence simulations under both isotropic ( @xmath183-plane ) and anisotropic ( @xmath134-plane ) dynamics . such simulations are standard in oceanography , see e.g. @xcite for details . we model the velocities of the lagrangian trajectories as complex - valued time series following a matrn process , where energy is equally divided between rotary components such that @xmath286 the motivation for using the matrn is based on observations : both the matrn and lagrangian trajectories such as these exhibit close to power law behaviour at mid - to - high frequencies ( see the review paper of @xcite ) . moreover , in contrast to fractional brownian motion , the power law behaviour of a matrn breaks at low frequency making the process stationary ( and not self - similar ) this is again consistent with @xcite where ocean - flow velocities are expected to be stationary , approximately gaussian and have finite spectral energy at very low frequencies . in addition to modelling the two rotary components as matrn processes having the same parameters , we also account for potential anisotropy by modelling the rotary coherence . this is done using the following 1-parameter model : @xmath287 where we set @xmath288 ; thus , the full model now has a total of four parameters . this simple coherence model naturally defines a timescale at which anisotropy begins , as the coherence is zero at @xmath289 , corresponding to a period of @xmath290 , and then increases linearly as frequency decreases until at long timescales all energy is in the dominant cartesian component . equation defines the rotary cross - spectrum and should be correctly blurred , together with the spectrum of the matrn process ( equation ) , as detailed in section [ s : whittle ] . the appropriateness of the blurred whittle likelihood fit is displayed in figure [ figanisofit ] for a trajectory from the anisotropic numerical simulation shown in the left panel of fig 2 . here we have used a semi - parametric fit by excluding the upper half of the frequency range ( @xmath291 ) and well as the zero frequency as we can not estimate @xmath292 here . the extra parameter in our model has succinctly captured the difference between the flow in each cartesian component ( @xmath22 and @xmath23 ) at low frequencies . thus the matrn model plus frequency - domain coherence as in equation appears to generally be a good fit for these complex - valued trajectories . isotropic and anisotropic matern model fits to a trajectory drawn from the anisotropic numerical simulation shown in the left panel of figure [ figvorticities ] . ( top left ) the matrn fit @xmath293 to the periodogram @xmath294 . ( top right ) the likelihood fit @xmath295 to the normalised rotary cross spectrum @xmath296 . ( bottom left ) the anisotropic and isotropic model fits to the periodogram @xmath297 in the @xmath22 direction and ( bottom right ) the anisotropic and isotropic model fits to the periodogram @xmath298 in the @xmath23 direction.,scaledwidth=85.0% ] to put our choice of model under further scrutiny , we fit this 4-parameter anisotropic matrn model to 248 trajectories from the anisotropic experiment ( of length 1,001 ) and compare the likelihood score versus the null hypothesis of a three - parameter isotropic matrn model , in which the frequency - domain coherence is identically zero . we can then use a likelihood ratio test as described in section [ impropriety ] to test for evidence of anisotropy . for consistency , we also repeat this procedure with the same number of trajectories ( of the same length ) from the isotropic experiment in figure [ figvorticities ] ( right ) to see if we correctly do not reject the null in such cases . the set of likelihood ratio test statistics from both experiments is displayed in figure [ figanisohist ] ( left ) . the statistics are compared with the 95% one - sided confidence interval for the @xmath299 distribution , as there is only 1 additional parameter in the anisotropic model . the isotropic model is correctly always rejected for the anisotropic data and rejected only 12 times for the isotropic data . this is in agreement with a type i error level set to 5% . in experimental rather than controlled data we would account for multiple testing issues if performing this test over multiple trials , applying techniques such as false discovery rates . in addition to the anisotropy , the timescale associated with these anisotropies are of interest . because the data was simulated , we can assess which frequencies are associated with the anisotropic behaviour from the settings . a spatial scale known as the rhines scale @xcite , well known in oceanography , determines the scale at which the transition to anisotropic large - scale behaviour begins ; this can be converted to a temporal scale through a division by the root - mean - square velocity . this gives a time - scale of approximately 23 days for the anisotropic experiment . figure [ figanisohist ] ( right ) gives an estimate of this timescale from our spectral model , based on the estimate of the frequency at which the rotary coherence is zero , which is @xmath300 . the median value is found to be 24.7 days , consistent with the 23 days computed from the rhines scale . this apparent ability to infer a key _ spatial _ scale based solely on the _ frequency _ structure of lagrangian trajectories is an interesting result which warrants further investigation . ( left ) likelihood ratio statistics computed from 248 isotropic and anisotropic trajectories where the first column contains 195 values . the 95% confidence interval is from the @xmath299 distribution . ( right ) anisotropy timescale estimates @xmath301 from the anisotropic trajectories.,title="fig:",scaledwidth=40.0% ] ( left ) likelihood ratio statistics computed from 248 isotropic and anisotropic trajectories where the first column contains 195 values . the 95% confidence interval is from the @xmath299 distribution . ( right ) anisotropy timescale estimates @xmath301 from the anisotropic trajectories.,title="fig:",scaledwidth=40.0% ] these results show that the rotary modelling techniques we have developed are therefore a powerful tool for capturing and quantifying physical structure in complex - valued processes . translating the temporal content garnered from multiple trajectories using our methods , to local spatial summaries , is an important avenue for future work . as a second application , we shall analyse a seismic time series . the left panel of figure [ ellipse1 ] shows the vertical and radial component of the seismic trace from the feb . 9 , 1991 earthquake in the solomon islands , as recorded from the pasadena recording station in california , usa . the paired observations are displayed in figure [ ellipse1 ] . the two components together represent a rayleigh wave , corresponding to elliptical retrograde motion in the direction of propagation of the wave . for more details , see @xcite and references therein . it is particularly important to capture the delay between the two components , as this incorporates phase misalignments between components , that in turn characterise the wave . here we model the earthquake extending the complex - valued auto - regressive ( complex ar ) process of @xcite . specifically , to capture the ellipticity of the time series , we propose an improper complex ar process given by @xmath302 where @xmath303 is i.i.d . complex - valued gaussian noise with mean 0 , variance @xmath304 and complex - valued relation @xmath305 . the improper complex ar process has 7 parameters . in practice however only 5 need to be estimated , as the orientation and inclination of the noise term ( defined through its relation ) is set to match that of the autoregressive part . the 5 parameters together define the damping , rate of spin , magnitude of variability , and the inclination and eccentricity of the ellipse . we use the blurred whittle likelihood for complex - valued processes to fit the improper complex ar process to the data , by deriving the form of the autocovariance of @xmath36 . in figure [ ellipse2 ] we show the fit to the periodogram and complementary spectrum for a 200-length portion of data from time @xmath306 to @xmath307 , corresponding to the most energetic period ( as displayed in figure [ ellipse1 ] ) . the features of the data are well captured by the extended ar model of . the impropriety is captured through both the asymmetry in the periodogram and the non - zero energy evident in the complementary spectrum . note that we perform a semi - parametric fit to the lowest 25% of observed frequencies ( as the data is contaminated by superimposed measurement noise ) and we exclude zero frequency from the fit as the sample mean has been removed . we have superimposed the second moment ellipse given by a improper complex ar process with the optimised parameters , over the time series in figure [ ellipse1 ] ( right ) . the elliptical structure has been captured and summarised by this process and can be used to track changes over time by segmenting the data . in particular we can describe the type of polarisation via @xmath308 , which captures the nature of wave propagation . ( left ) vertical ( blue ) and radial ( red ) seismic traces from the feb . 9 , 1991 earthquake in the solomon islands , as recorded from the pasadena recording station in california , usa . ( right ) the vertical and radial components ( in the time window from @xmath306 to @xmath307 ) as a complex - valued trajectory ( in blue ) . we also superimpose the second - moment ellipse ( in red ) from an improper complex ar process with parameters selected from the blurred whittle likelihood.,title="fig:",scaledwidth=38.0% ] ( left ) vertical ( blue ) and radial ( red ) seismic traces from the feb . 9 , 1991 earthquake in the solomon islands , as recorded from the pasadena recording station in california , usa . ( right ) the vertical and radial components ( in the time window from @xmath306 to @xmath307 ) as a complex - valued trajectory ( in blue ) . we also superimpose the second - moment ellipse ( in red ) from an improper complex ar process with parameters selected from the blurred whittle likelihood.,title="fig:",scaledwidth=38.0% ] improper complex ar fit to the seismic data from figure [ ellipse1 ] ( right ) using the blurred whittle likelihood . ( left ) is the periodogram ( in decibels ) , ( centre ) is the real part of the complementary spectrum and ( right ) is the imaginary part ( on a linear scale due to negative values).,title="fig:",scaledwidth=30.0% ] improper complex ar fit to the seismic data from figure [ ellipse1 ] ( right ) using the blurred whittle likelihood . ( left ) is the periodogram ( in decibels ) , ( centre ) is the real part of the complementary spectrum and ( right ) is the imaginary part ( on a linear scale due to negative values).,title="fig:",scaledwidth=30.0% ] improper complex ar fit to the seismic data from figure [ ellipse1 ] ( right ) using the blurred whittle likelihood . ( left ) is the periodogram ( in decibels ) , ( centre ) is the real part of the complementary spectrum and ( right ) is the imaginary part ( on a linear scale due to negative values).,title="fig:",scaledwidth=30.0% ] in this paper we have addressed parametric modelling and inference for complex - valued time series , with a focus on the appropriate implementation of the whittle likelihood . we have shown the value of separating out different frequency behaviour and providing a model for the ranges of frequencies separately . this permitted us to handle a plethora of different effects directly in the frequency domain , and introduce new parametric model characteristics . for example , we demonstrated how our techniques can be used to effectively capture anisotropy in oceanographic flow models and seismic data . a primary contribution of this paper is the usage of the blurred whittle likelihood for estimating the parameters of stochastic processes . this allowed us to significantly reduce bias and estimation error , while still keeping computations relatively efficient , as evidenced in a monte carlo study comparing with state of the art alternatives . this , combined with good frequency - domain models for the spectrum , yielded flexible yet parsimonious models for physical time series . in this paper , we assume that the distribution of the fourier transform of the process has a jointly gaussian distribution , in order to derive properties of our proposed inference method . it is important to point out that this assumption is not as strict as it may seem . processes that are non - gaussian in the time domain may in fact have fourier transforms with approximately gaussian distributions for sufficiently large sample size . this is a consequence of a central limit theorem , see @xcite , who also provides formal conditions when the gaussian assumption is asymptotically valid . @xcite provide practical examples which satisfy such conditions . if the process is non - gaussian in the frequency domain and if higher - order structure is of interest , then methods for modelling higher order complex structure must be used , see for example @xcite . there remain significant challenges in frequency domain analysis of time series , both methodological and applied . a key methodological challenge is to extend the use of the whittle likelihood to nonstationary complex - valued time series . this can be performed by explicitly modelling nonstationary components and their effect on the spectra , or by extracting them from the likelihood . we note that the innovations made in this paper , which account for blurring effects from finite sampling , will be key to correctly separating blurring effects from time variability . the main challenge in applications is to continue building models from our framework for use in a wide range of physical applications , and then working with these other disciplines to interpret the results scientifically . we first note note that from the definition given in equation @xmath309 we start by finding the spectral representations linking cartesian ( @xmath55 ) to complex ( @xmath56 ) representations , building from the spectral increment processes , @xmath310 e^{i\omega t}\\ \nonumber y_t&=\frac{1}{2i}\int_{-\infty}^{\infty } \left[d\psi_z\left(\omega\right)-d\psi_z^\ast\left(-\omega\right ) \right ] e^{i\omega t}\\ \nonumber \rightarrow d\psi_x\left ( \omega\right)&=\frac{1}{2}\left[d\psi_z\left(\omega\right)+d\psi_z^\ast\left(-\omega\right ) \right]\\ \nonumber s_{xx}(\omega)&={\frac{1}{4}\left[s_{zz}(\omega)+s_{zz}(-\omega ) + 2\re\left\ { r_{zz}(\omega)\right\}\right]}\\ \nonumber \rightarrow d\psi_y\left ( \omega\right)&=\frac{1}{2i}\left[d\psi_z\left(\omega\right)-d\psi_z^\ast\left(-\omega\right ) \right]\\ \nonumber s_{yy}\left ( \omega\right)&={\frac{1}{4}\left[s_{zz}(\omega)+s_{zz}(-\omega ) -2\re\left\ { r_{zz}(\omega)\right\}\right]}\\ \nonumber s_{xy}\left(\omega\right)&={\frac{i}{4}\left[s_{zz}\left(\omega\right)-s_{zz}\left(-\omega\right)-2i\im\ { r_{zz}(\omega)\}\right ] } .\nonumber\end{aligned}\ ] ] we represent the complex components ( @xmath56 ) in terms of cartesian components ( @xmath55 ) @xmath311 all the relationships thus far hold for all @xmath65 . with rotary decompositions , there is no spectral energy for @xmath312 as processes are analytic . we also have to be careful at frequency @xmath58 , as the energy at this frequency is shared between rotary components . we shall therefore separate the behaviour for different mathematical signs of @xmath65 . we first write the rotary decomposition ( @xmath57 ) in terms of complex components ( @xmath56 ) @xmath313 showing the relationship in reverse , i.e. from complex ( @xmath56 ) to rotary ( @xmath57 ) , we obtain that @xmath314 this specifies the relationships in the table for @xmath98 , and also the different relationships at @xmath58 . we next show the relationship of the complex representation ( @xmath56 ) in terms of cartesian components ( @xmath55 ) : @xmath315\\ d\psi_{z^+}\left ( \omega\right)&=\frac{1}{2}d\psi_{x}\left ( \omega\right)\left[1 + { \mathrm{sgn}}(\omega)\right ] + \frac{i}{2}d\psi_{y}\left ( \omega\right)\left[1 + { \mathrm{sgn}}(\omega)\right]\\ s_{++}\left ( \omega\right)&=\frac{1}{4}s_{xx}\left ( \omega \right)\left(\left[1 + { \mathrm{sgn}}(\omega)\right]^2\right ) + \frac{1}{4}s_{yy}\left ( \omega \right)\left(\left[1 + { \mathrm{sgn}}(\omega)\right]^2\right)\\ & \quad -\frac{i}{4}s_{xy}(\omega)\left(\left[1 + { \mathrm{sgn}}(\omega)\right]^2\right ) + \frac{i}{4}s_{xy}^\ast(\omega)\left(\left[1 + { \mathrm{sgn}}(\omega)\right]^2\right)\\ & = { \left[s_{xx}\left ( \omega \right)+s_{yy}\left ( \omega \right)+2\im s_{xy}\left ( \omega \right)\right ] \left({\ensuremath{\operatorname{\mathbb{i}}}}(\omega>0)+\frac{1}{4}{\ensuremath{\operatorname{\mathbb{i}}}}(\omega=0)\right)}\end{aligned}\ ] ] @xmath316\\ d\psi_{z^-}\left ( \omega\right)&=\frac{1}{2}d\psi_{x}\left ( \omega\right)\left[1 + { \mathrm{sgn}}(\omega)\right ] -\frac{i}{2}d\psi_{y}\left ( \omega\right)\left[1 + { \mathrm{sgn}}(\omega)\right]\\ s_{--}\left ( \omega\right)&=\frac{1}{4}s_{xx}\left ( \omega \right)\left(\left[1 + { \mathrm{sgn}}(\omega)\right]^2\right ) + \frac{1}{4}s_{yy}\left ( \omega \right)\left(\left[1 + { \mathrm{sgn}}(\omega)\right]^2\right)\\ & \quad + \frac{i}{4}s_{xy}(\omega)\left(\left[1 + { \mathrm{sgn}}(\omega)\right]^2\right ) -\frac{i}{4}s_{xy}^\ast(\omega)\left(\left[1 + { \mathrm{sgn}}(\omega)\right]^2\right)\\ & = { \left[s_{xx}\left ( \omega \right)+s_{yy}\left ( \omega \right)-2\im s_{xy}\left ( \omega \right)\right ] \left({\ensuremath{\operatorname{\mathbb{i}}}}(\omega>0)+\frac{1}{4}{\ensuremath{\operatorname{\mathbb{i}}}}(\omega=0)\right)}\\ s_{+-}\left ( \omega\right ) & = { \left[s_{xx}(\omega)-s_{yy}(\omega)+2i\re \{s_{xy}(\omega ) \}\right]\left({\ensuremath{\operatorname{\mathbb{i}}}}(\omega>0)+\frac{1}{4}{\ensuremath{\operatorname{\mathbb{i}}}}(\omega=0)\right)}.\end{aligned}\ ] ] finally we show the relationship of the cartesian components ( @xmath55 ) in terms of rotary components ( @xmath57 ) . these can be found by going from cartesian to complex , and then complex to rotary using the algebra above . @xmath317}{\ensuremath{\operatorname{\mathbb{i}}}}(\omega\neq0 ) \\&\quad+2[s_{+-}(\omega)+\re\{r_{+-}(\omega)\}]{\ensuremath{\operatorname{\mathbb{i}}}}(\omega=0)\\ s_{yy}(\omega)&={\frac{1}{4}\left[s_{++}(|\omega|)+s_{--}(|\omega| ) -2\re\left\ { s_{+-}(|\omega|)\right\}\right]}{\ensuremath{\operatorname{\mathbb{i}}}}(\omega\neq0 ) \\&\quad+2[s_{+-}(\omega)-\re\{r_{+-}(\omega)\}]{\ensuremath{\operatorname{\mathbb{i}}}}(\omega=0)\\ s_{xy}(\omega)&=\frac{1}{2}\im\{s_{+-}(\omega)\}+\frac{1}{4}\mathrm{sgn}(\omega)i(s_{++}(\omega)-s_{--}(\omega)){\ensuremath{\operatorname{\mathbb{i}}}}(\omega\neq0 ) \\&\quad+2\im\{r_{+-}(\omega)\}{\ensuremath{\operatorname{\mathbb{i}}}}(\omega=0).\end{aligned}\ ] ] the relationships for @xmath98 are in table [ table : realcomplex ] , and relationships for @xmath58 can be found in this section by using the appropriate indicator function , @xmath318 , where necessary . @xcite prove that the necessary _ and _ sufficient conditions for a bivariate ( @xmath122 ) matrn process , with matrn cross - covariances , are @xmath319 where in the case @xmath320 and @xmath321 this condition simplifies to @xmath322 this condition appears to suggest that our specification in equation does not permit a full bivariate matrn for all constant @xmath323 for certain values of @xmath324 and @xmath325 , and similarly with equation , @xmath326 appears not always valid for certain values of @xmath327 and @xmath328 . this is however because of the different normalisations of the matrn ( compare equation with equation ( 1 ) in @xcite ) , meaning restrictions on the correlation coefficient @xmath329/@xmath330 and @xmath331 are _ not _ identical . to equate the representations we examine the spectrum of the @xcite representation , denoted @xmath332 , and the cartesian spectrum , denoted @xmath13 , which for continuous - time processes is given in equation : @xmath333 and similarly for @xmath334 and @xmath68 . note that the same reasoning follows for rotary models specified by @xmath94 , @xmath141 and @xmath335 . returning to the comparison with cartesian components , we next calculate : @xmath336}}{\pi^{1/2}}\frac{\gamma(\frac{1}{2}(\nu_1+\nu_2)+\frac{1}{2})}{\gamma(\frac{1}{2}(\nu_1+\nu_2 ) ) } } { ( \omega^2+\alpha_{12}^2)^{1/2(\nu_1+\nu_2)+1/2 } } \nonumber \\ & = & \frac{\gamma(\nu_1+\frac{1}{2})^{1/2}}{\gamma(\nu_1)^{1/2}}\frac{\gamma(\nu_2+\frac{1}{2})^{1/2}}{\gamma(\nu_2)^{1/2 } } \frac{\gamma(\frac{1}{2}(\nu_1+\nu_2))}{\gamma(\frac{1}{2}(\nu_1+\nu_2)+\frac{1}{2})}\frac{s_{12}(\omega)}{\rho_{12}},\label{e : gneitingcond}\end{aligned}\ ] ] where the last line follows from equation ( 4 ) in @xcite . however , from equation we have that for constant @xmath329 across all frequencies : @xmath337 contrasting equations and , it therefore follows that condition is equivalent to @xmath338 in our representation ( and similarly @xmath339 for rotary components ) . we prove theorem 1 via three propositions . in this section we only analyse the real - valued sampled process @xmath22 , we therefore drop the @xmath22 and @xmath340 subscript notation from @xmath341 and @xmath342 . assume that the sequence @xmath2 is a zero - mean second - order stationary process with spectral density @xmath343 . assume that the spectral density of @xmath2 is bounded above by the finite value @xmath344 . then the covariance of the discrete fourier transform ( dft ) of a sample @xmath12 , defined by @xmath345 is bounded , for some choice of @xmath346 ( where @xmath347 ) , by @xmath348\right\},\end{aligned}\ ] ] where @xmath349 , @xmath350 and @xmath351 . we start by defining the dirichlet kernel as @xmath352 we will make use of two properties of the dirichlet kernel . first , we have from ( * ? ? ? * theorem 15.2 ) that : @xmath353 second , we have from ( * ? ? ? * lemma 5 ) that @xmath354 we now quantify the correlation of the fourier transform between frequencies @xmath355 and @xmath356 . this takes the form of @xmath357 without loss of generality we take @xmath358 , which constrains @xmath359 . we assume that @xmath360 can be upper bounded by @xmath344 , i.e. @xmath361 , and therefore note that @xmath362 we now implement a change of variables , recalling the periodicity of the integrand , and rewrite this integral as @xmath363 we note that because we have assumed that @xmath364 is sufficiently large we can split up the range of integration . specifically we define the range @xmath365 note that @xmath366 is a free variable and only enters into our method of bounding , conditional on the choice of @xmath367 and @xmath368 . we therefore have that @xmath369 we shall now bound these individual contributions one - by - one where we use combinations of the relationships given in equations and . we start by considering @xmath370 for the first term @xmath371 we use condition @xmath372\,d\omega'\\ & = \frac{\pi}{2 n \delta_\omega } \left[\log \frac{\pi-\delta_{\omega}}{\pi}-\log \frac{\omega_p}{\omega_p+\delta_{\omega}}\right ] \le\frac{\pi}{2 n \delta_\omega}\left[\log\left(1 + \frac{\delta_\omega}{\omega_p}\right)-\log \frac{\pi}{\pi-\delta_\omega}\right]\\ & \le\frac{\pi}{2 n \delta_\omega}\left[\frac{\delta_{\omega}}{\omega_p}-\log \frac{\pi}{\pi-\delta_\omega}\right]= \frac{\pi}{2 n\omega_p}-\frac{\pi}{2n\delta_\omega}\log\frac{\pi}{\pi-\delta_\omega } = \frac{1}{4j_p}-\frac{\pi}{2n\delta_\omega}\log\frac{\pi}{\pi-\delta_\omega}.\end{aligned}\ ] ] for the next term @xmath373 we use the periodicity of the dirichlet kernel and condition @xmath374\,d\omega ' \\ & = \frac{\pi}{2 n}\frac{1}{2\pi-\delta_\omega}\left[\log\frac{\pi}{\pi-\delta_{\omega}}-\log\frac { \pi-\delta_\omega}{\pi}\right]=\frac{\pi}{n(2\pi-\delta_\omega)}\log\frac{\pi}{\pi-\delta_{\omega}}.\end{aligned}\ ] ] this establishes the behaviour of the first integral . for @xmath375 we use both and @xmath376 \le\frac{1}{\pi^2(|j_1-j_2|-j_p)}\left[\log(j_p)+{\mathcal o}(1)\right].\end{aligned}\ ] ] the bound on the third term uses condition @xmath377\ , d\omega=\frac{\pi}{2n\delta_\omega}\left[-\log\left(\frac{\omega_p}{\delta_\omega-\omega_p}\right ) + \log\left(\frac{\delta_\omega-\omega_p}{\omega_p}\right)\right]\\ & = \frac{\pi}{n\delta_\omega}\log\left(\frac{\delta_\omega-\omega_p}{\omega_p}\right)= \frac{\pi}{n\delta_\omega}\log\left(\frac{\delta_\omega}{\omega_p}-1\right)\le \frac{\pi}{n\omega_p } = \frac{1}{2j_p}.\end{aligned}\ ] ] the fourth term resembles the second term , and thus takes the form of @xmath378.\end{aligned}\ ] ] finally , we have that the fifth integral takes the form of @xmath379 as @xmath380 , the @xmath381 terms in @xmath371 , @xmath373 and @xmath382 sum to a negative value and can hence be ignored . the proposition follows by summing the remaining terms in the integral . assume that the sequence @xmath2 is a zero - mean second - order stationary process with spectral density @xmath343 . assume that the spectral density of @xmath16 is bounded above by the finite value @xmath344 . for a sample @xmath12 , and a given choice of @xmath383 , linear combinations of the periodogram have a variance that aggregates according to @xmath384}{3n\pi^2 } \right].\ ] ] furthermore the optimal choice corresponds to @xmath385 in which case we obtain that @xmath386}{3n\pi^2 } \right ] \\ & = a_{\max}^2\|s\|^2_{\infty } \frac{3}{n^{2/3}}\left\{1+o(1)\right\}.\end{aligned}\ ] ] @xmath387 we shall now determine what this aggregates to . we start by writing @xmath388 using the fact that the fourier transform of a gaussian process is also gaussian we may use isserlis theorem and so obtain that @xmath389 thus it follows that @xmath390 we therefore find that @xmath391 using proposition 1 , it follows that @xmath392\right\}^2\\ & \leq \frac{1}{n^2}\sum_{j_1=1}^{\lfloor n/2 \rfloor}\sum_{j_2=j_1 + 2j_p+1}^{\lfloor n/2 \rfloor } \|s\|^2_{\infty}\left\{\frac{2}{j_p^2}+\frac{8}{\pi^4(|j_1-j_2|-j_p)^2}\left[\log^2(j_p)+{\mathcal o}(\log(j_p))\right]\right\}\\ & = \|s\|^2_{\infty}\left(\widetilde{c}_{12}^{(1)}+\widetilde{c}_{12}^{(2)}\right).\end{aligned}\ ] ] first we note that @xmath393 then we bound the second term @xmath394\\ & \le \frac{8\left[\log^2(j_p)+{\mathcal o}(\log(j_p))\right]}{n^2\pi^4 } \sum_{j_1=1}^{\lfloor n/2 \rfloor}\sum_{\tau=2j_p+1}^{\lfloor n/2 -j_1\rfloor } \frac{1}{(\tau - j_p)^2}\\ & \le \frac{4\left[\log^2(j_p)+{\mathcal o}(\log(j_p))\right]}{n\pi^4 } \sum_{\tau = j_p+1}^{\lfloor n/2-j_p \rfloor } \frac{1}{\tau^2}\le \frac{4\left[\log^2(j_p)+{\mathcal o}(\log(j_p))\right]}{n\pi^4 } \sum_{\tau=1}^{\infty } \frac{1}{\tau^2}\\&=\frac{4\left[\log^2(j_p)+{\mathcal o}(\log(j_p))\right]}{n\pi^4}\zeta(2)= \frac{4\left[\log^2(j_p)+{\mathcal o}(\log(j_p))\right]}{n\pi^4}\frac{\pi^2}{6},\end{aligned}\ ] ] where we have used a bound based on the riemann zeta function at an argument of 2 @xmath395 thus it follows that @xmath396.\end{aligned}\ ] ] finally , as @xmath397 the first statement of the proposition follows . to select the optimal order of @xmath398 we see that : @xmath399\rightarrow x_{\mathrm { opt}}^3=n,\quad \rightarrow x_{\mathrm { opt}}=n^{1/3}.\ ] ] the optimal rate is therefore achieved if we select @xmath400 . assume that the sequence @xmath2 is a zero - mean second - order stationary process with spectral density @xmath343 . for a sample @xmath12 , we define the frequency domain likelihood as @xmath401 . \label{seq : likelihood}\end{aligned}\ ] ] assume that we chose @xmath402 and that the frequency domain likelihood @xmath403 has two continuous derivatives in @xmath404 . assume that the spectral density of @xmath16 is bounded above by the finite value @xmath233 and below by the non - zero value @xmath234 . then the score @xmath405 and the hessian @xmath406 , the derivatives of equation , satisfy @xmath407 and @xmath408 we start by noting that @xmath409.\end{aligned}\ ] ] if we calculate expectations then @xmath410=0.\end{aligned}\ ] ] furthermore , using proposition 2 , the variance of the score takes the form of @xmath411 where @xmath412 and @xmath413 . we can therefore conclude using chebychev s inequality that we can fix @xmath414 such that @xmath415 we may therefore deduce that @xmath416 as @xmath417\\ \nonumber & = -\sum_{\omega\in \omega}\left [ -\frac{\left(\frac{\partial \bar s\left(\omega ; \theta\right ) } { \partial \theta } \right)^2}{\bar s^2\left(\omega ; \theta\right)}+\frac{\frac{\partial^2 \bar s\left(\omega ; \theta\right ) } { \partial \theta^2 } } { \bar s\left(\omega ; \theta\right)}\right]\\ & \qquad -\sum_{\omega\in \omega}\left [ 2\frac{\left(\frac{\partial \bar s\left(\omega ; \theta\right ) } { \partial \theta } \right)^2}{\bar s^3\left(\omega ; \theta\right)}-\frac{\frac{\partial^2 \bar s\left(\omega ; \theta\right ) } { \partial \theta^2 } } { \bar s^2\left(\omega ; \theta\right)}\right]\hat s\left(\omega\right).\end{aligned}\ ] ] thus we may note that @xmath418 furthermore , we have that , @xmath419\hat s\left(\omega\right)\right\}.\end{aligned}\ ] ] we define @xmath420 in this instance we can bound the variance , using proposition 2 , by @xmath421 we can therefore again conclude using chebychev s inequality that @xmath422 this yields the second result . we now prove theorem 1 . we let @xmath423 lie in a ball centred at @xmath424 with radius @xmath425 . we additionally define the hessian matrix @xmath426 @xmath427 then @xmath428 inverting this equation for @xmath429 , and using that @xmath430 , we obtain with the assumption on continuity on @xmath431 that @xmath432 where as usual @xmath433 is the matrix of all ones , see @xcite . additionally define @xmath434 thus it follows that @xmath435^{-1}\frac{1}{n}\frac{\partial } { \partial \theta}\ell_f\left(\bm{\theta}\right)\nonumber\\ & = -\left[\frac{1}{n}{\bm{h}}\left(\bm{\theta}\right)+{\cal o}_p\left ( { \mathbf{j}}\frac{1}{n^{1/3}}\right)+o_p({\mathbf{j}})\right]^{-1}{\cal o}_p\left ( \frac{1}{n^{1/3}}\right)\nonumber\\ & = \left[\frac{1}{n}{\bm{h}}\left(\bm{\theta}\right)\right]^{-1}\left[\mathbf{i}+o_p(1)+{\cal o}_p\left ( \frac{1}{n^{1/3}}\right)\right ] { \cal o}_p\left ( \frac{1}{n^{1/3}}\right)\nonumber\\ & = { \cal o}_p\left ( \frac{1}{n^{1/3}}\right),\end{aligned}\ ] ] using proposition 3 , and applying slutsky s theorem @xcite , which yields the result . we outline how the likelihood ratio test statistic is distributed in the case of complex - valued observations . as it is not important to outline the full interaction between complex - valued observations and blurring , to save on complicated descriptions we shall therefore describe complex - valued but unblurred descriptions . we shall consider the special cases of @xmath436 where the null and alternate parameters are denoted as @xmath437 we shall now develop a test for the null hypothesis of @xmath438 we note that the hypotheses are nested or fall into this framework if one can reproduce @xmath439 by choices of @xmath424 . therefore for the special case used in section [ ss : simulations2 ] where @xmath440 we therefore have that if @xmath441 , @xmath442 , so any value of @xmath279 greater than @xmath443 can reproduce null in the space of the alternate . the theory in this section is therefore valid for the example of section [ ss : simulations2 ] . we start from the whittle likelihood function for rotary components . we write @xmath172 for the set of frequencies that we shall estimate parameters over and model the spectrum over . we also define from the dft of the observed process @xmath36 written as @xmath444 : @xmath445 these two fourier transforms are the analytic and anti - analytic parts of @xmath36 respectively . using equation we can rewrite the log - likelihood of the complex - valued process to be @xmath446+j_\pm^h(\omega){\mathbf{s}}_{\pm}^{-1}\left(\omega;\bm{\theta}_p\right ) j_\pm(\omega)\right\},\quad p = 0,1.\ ] ] note that we do not need to include zero frequency in the hypothesis test as no information on impropriety is contained here , so this will simply cancel out when comparing the null with the alternate . we shall now compare the hypothesis @xmath439 with reality using the log - likelihood . we start by defining @xmath447 and also write @xmath448 we look at the difference of log - likelihoods via @xmath449 this implicitly defining the random variables @xmath450 and @xmath451 . we now wish to derive the distribution of this , especially given the original data was gaussian . we obtain that under the null model @xmath452 furthermore under the null we also have that @xmath453 we now need to combine our results for @xmath450 and @xmath451 to determine the characteristics of the likelihood ratio test . from @xcite we observe that that @xmath454 we are therefore in a position to simplify the expression of by just substituting in equation into equation to obtain @xmath455 this derives the distribution for the hypothesis test . if we are in the regime where the covariance starts to become appreciable , modifications to the proof must be implemented ; however this illustrates how to implement a test for propriety based on a parametric model . we wish to thank dr james s. martin for spotting an error in the derivations of section [ sm : matern ] . apanasovich , t. v. , genton , m. g. and sun , y. ( 2012 ) a valid matrn class of cross - covariance functions for multivariate random fields with any number of components . _ , * 107 * , 180193 . brands , p. j. , hoeks , a. p. , ledoux , l. a. and reneman , r. s. ( 1997 ) a radio frequency domain complex cross - correlation model to estimate blood flow velocity and tissue motion by means of ultrasound . _ ultrasound med . _ , * 23 * , 911920 .

this paper introduces new parametric models for the autocovariance functions and spectra of complex - valued time series , together with novel modifications of frequency - domain parameter inference methods appropriate for such time series . in particular , we introduce a version of the frequency - domain whittle likelihood for complex - valued processes . this represents a nontrivial extension of the whittle likelihood for bivariate real - valued processes , as complex - valued models can capture structure that is only evident by separating negative and positive frequency behaviour . flexible inference methods for such parametric models are proposed , and the properties of such methods are derived . the methods are applied to oceanographic and seismic time series , as examples of naturally occurring sampled complex - valued time processes . we demonstrate how to reduce estimation bias of the whittle likelihood caused by leakage and aliasing , improving parameter estimation of both real - valued and bivariate / complex - valued processes . we also provide techniques for testing the series propriety or isotropy , as well as procedures for model choice and semi - parametric inference . + + * keywords : * frequency domain ; whittle likelihood ; discrete fourier transform ; periodogram ; aliasing ; leakage ; semi - parametric inference ; matrn process ; propriety ; anisotropy .

invasive cervical cancer , one of the most common malignant tumor of women is usually the second or third . place , behind breast cancer and colorectal cancer ( colon cancer ) . according to the international union for the fight against cancer ( iucc ) it is believed that these diseases cause 3 to 5% of deaths because of cancer . according to latest estimates 466,000 new cases of cervical cancer almost 80% of that number are diagnosed in developing countries ( melanesia , africa , central and south america ) , where screening programs are not implemented or poorly organized . in most countries the incidence of invasive cancer is very low for women under 25 years.incidence grows about 35 to 40 years and reaches a maximum in the fifties and sixties . average time required for the development of cevical cancer is 10 years , and it usually occurs from 48 to 52 years , in recent times is evident that the incidence of , and mortality from cervical cancer , especially among young women , rises . infection by human papilloma virus ( hpv ) is the biggest risk factor for disease emergence . although hpv infection is an important element for the development of cervical cancer , it is not sufficient for the development of the malignant transformation . other cofactors participate in the process : the early entry into sexual relations , a higher number of sexual partners , multiple pregnancies , sexually transmitted infections , low socio - economic standard of living , stressful events , the situation of hopelessness and depression , smoking , use of oral contraceptives for a long time , alcohol , chemotherapeutics , immunosuppression , factors related for male partners ( number of sexual partners , visiting prostitutes , male age at the time of the first relationship , infection of genital organs , the existence of condyloma or penile cancer ) . today it is known that the disease develops from precancerous changes ( dysplasia known as the general ) , advancing from low , through moderate and severe dysplasia . next stage is cancer in situ , and the next one is the invasive cancer . the time required for the progression from dysplasia to invasive cancer is variable , but it is estimated that is 10 - 15 years . for the diagnosis of premalignant and malignant changes today , there are a few methods . in addition to cytology ( pap - pap test ) , which after more than half a century since the introduction of the practice remains sovereign screening methods for detection of cervical cancer , the most important place in the early diagnosis of cervical changes take colposcopy ( examination of cervix , under conditions of good lighting and magnification ) and target biopsy ( snippet ) . screening aims to detect disease in apparently healthy people and such a serious illness and death could be prevented . skrining for ca pvu can be organized or opportunistic ( disorganized , spontaneous , individual ) . each of the respondents , regardless of the reason for reporting gynecologist , in addition to the basic gynecological examination was done colposcopically and pap test review and , if necessary , cervical biopsy . from patients were collected data on age , qualifications , social origin , place of residence , marital status , deliberate and involuntary abortions , pregnancies and childbirth . it has been taken a detailed gynecological history , especially the part related to the review of cervix ( the time of the last review , the frequency of examinations for early detection of cancer , pre - located ) . 1028 women came to review to home health in velika plana , and 606 women fulfilled the conditions for opportunistic screening . other women did not meet the requirements because they were from other municipalities , have never had a sexsual relationship or they had their uterus removed . a number of women could not be carried out screening on the same day because of their strong secretion , bleeding , severe pain or because they came only to rewrite them or to cure breast examination and did not want gynecological examination . these women have pap smears and colposcopy scheduled the next day . from this group of 341 patients , which is scheduled to review , 122 patients did not respond to the scheduled examination ( 35.7% of the scheduled review ) . in 1028 screening is done to a small number of pregnant women because among pregnant women in the area there are prejudice that gynecological examination may jeopardize the pregnancy . in addition , they are mostly young women that this is the first contact with gynecologist and one very difficult to agree on the common view , and any additional examinations required by the screening program does not want to accept . from this passage we can clearly see two major limitations in the performance of spontaneous ( opportunistic ) screening . the first problem is that there is no legal provision which obligate women to respond to the invitation for screening , and the other is lack of information and poor education of patients , which leaves room for prejudices that can be eradicated only be painstaking many years of work . the study group of patients belong to the age of 15 to 80 years , and most of them belong to the ages of 30 to 59 years . given that the goal of screening for cervical cancer detection of pemalignant lesions , screening should be targeted to the group of women who probably could have premalignant lesions , which is between 25 and 35 years . in the study population women from 25 to 30 years are somewhat less common in this group and this indicates the need for greater attention be paid to the motivation of these women for gynecological examinations and screening(fig.1 ) . in the study group , 274 ( 45.2% ) patients were from the city , and 332 ( 54.8% ) patients were from the village , which shows that a slightly greater representation of patients from rural areas , and this is in contradiction with the assumption that because of better access to health care of patients from the city should be higher . by comparing the marital status of patients with marital status of women in the general population census in 2002 . was found that the number of married women in the study group , 91.1% to 58.9% in the general population , and the number of unmarried in the study group 8.9% to 41.1% in the general population . so , the percentage of married women is far higher in the examined sample , and the percentage of unmarried women is far smaller in the study group compared to the general population . this relationship and examined the general population can be explained by a variety of reasons that married women leading gynecologist : pregnancy , contraception , abortion , any absence of menstruation , the condition after birth , problems related to lactation , infertility , menstrual disorders and a host of other problems that are inherent primarily married women(fig.2 ) . among the tested women 56.1% . have completed high school ( hs ) . their representation in the general population census in 2002 . the patient completed faculty and university students is 12.8% , and in the general population , their percentage was 4.5 . women with incomplete primary school ( ps ) education in the study group 6.1% to 36.1% in the general population . from these data it is clear that educated women are better motivated to gynecological examination and screening test of uneducated . it can be connected with better and bigger opportunities informations communications educated women , which contributes to raising their awareness of the importance of this type of examination for early detection of cervical cancer(fig.3 ) . according to the history of menstruation , this is the logical representation of women because the majority of gynecological problems ( and problems that these women bring to the review ) tied just generative period for women . most women assessed their material status as moderate ( 52.5% ) and good ( 25.1% ) , and at least as very poor ( 4.5% ) or very good ( 6.4% ) ( fig.4 ) . when it comes to the number of spontaneous and induced abortions obtained the result that 89.1% had no spontaneous miscarriages , and 43.6% of them had no deliberate miscarriages . the results show that there are multiple reasons why women came to the gynecological examination , but they are very evenly represented . only the control , without any problems , the percentage of such visits is low because patients generally think that if you do not feel any symptoms do not need to see a gynecologist and do not know how important it is to review when they come and not have problems because precancerous changes in the cervix generally do not have any symptoms . the analysis of data relating to the date of last visit i found that regular gynecological examinations occurs 37.8% of women . i also found that 45.7% of women surveyed had never had a pap test , and 88.4% of them never had colposcopy , only 4.1% of women for the first time in their life came the gynecological examination . also , for seven years ( 1997th to 2003rd , a period when opportunistic screening is not implemented ) diagnosed a total of 14 precancerous changes in the cervix ( table 1 ) , and for only two years of implementing the screening ( 2004th and 2005th ) diagnosed a total of 32 such changes , that with simple intervention can be removed and thus save the patient 's life ( table 2 ) . protocol analysis colposcopy and pap smears for women dispensaries i came to the fact that for seven years ( from the 1997th to 2003rd ) 772 colposcopys had been done , and for the two years since the introduction of opportunistic screening was done in 2933 colposcopic examination . from these data it can be concluded that the increase in the number of preventive examinations for cervical cancer resulted in increasing the number of diagnosed precancerous lesion which is the goal of screening . year remained unchanged , as expected given that the result of screening , in the form of reducing the number of malignant changes in the cervix , can be seen only in a few years . based on the results of the work i came to the following conclusions about the limitations and possibilities of opportunistic screening : limitations of opportunistic screening : 1 ) lack of information the patient about the importance of preventive screenings for cervical cancer is a major obstacle for opportunistic screening 2 ) in our country there is no legal provision that would oblige the patient to respond to the invitation for screening 3 ) most women come on irregular review so that it is not possible for them to do screening women for review come mainly if they have problems , very few women occurs only in control without any gynecological problems uneducated women rarely come to the view women who are not married rarely come to the view 7 ) poor service organized women 's health ( services that are not carried out screening ) is largely responsible for the high incidence and mortality of cervical cancer . possibilities of opportunistic screening : 1 ) at the gynecological examination more often come married women 2 ) women more often come from the countryside 3 ) educated women more regularl come to the gynecologist of the uneducated 4 ) women in their reproductive stage of life more often come to the gynecologist 5 ) the introduction of opportunistic screening significantly increased the number of pap smears and colposcopy 6 ) for two years the implementation of screening of precancerous lesions diagnosed almost 3 times larger than the sum of these changes are diagnosed in the last seven years when screening was not implemented . proposal of measures : 1 ) it is necessary to inform and educate women about the importance of screening for cervical cancer prevention . this can be conducted through individual interviews with patients in practice , through lectures and through the mass media 2 ) special attention to the uneducated , young ( from 25 - 35 years.and younger ) and unmarried women 3 ) talks and lectures to put emphasis on the necessity of regular visits to the gynecologist when there are no gynecological problems 4 ) organize a system to call patients for review which may provide adequate coverage of the population 5 ) regulate the legal obligation of responding to the call for screening .

majority of countries do nt have an organized screening program.it is not conducted or is in form of opportunistic screening . an organized screening for cervical cancer in developed countries is resulted in significant decrease of incidence and mortality . in our country there is no an organized screening program . even it is carried out , it is in form of opportunistic screening . consequently , the number of cervical carcinoma ( ca pvu ) is the largest in europe . the goal of this research is accomplishing possibilities and limits of opportunistic screening in velika plana .

SECTION 1. SHORT TITLE. This Act may be cited as the ``Community Savings and Investment Act of 2004''. SEC. 2. INCOME TAX ON QUALIFIED COMMUNITY LENDERS. (a) In General.--Section 11 of the Internal Revenue Code of 1986 (relating to tax imposed on corporations) is amended by redesignating subsection (d) as subsection (e) and by inserting after subsection (c) the following: ``(d) Qualified Community Lenders.-- ``(1) In general.--In the case of a qualified community lender, in lieu of the amount of tax under subsection (b), the amount of tax imposed by subsection (a) for a taxable year shall be the sum of-- ``(A) 15 percent of so much of the taxable income as exceeds $250,000 but does not exceed $1,000,000, and ``(B) the highest rate of tax imposed by subsection (b) multiplied by so much of the taxable income as exceeds $1,000,000. ``(2) Qualified community lender.--For purposes of paragraph (1), the term `qualified community lender' means a bank-- ``(A) which achieved a rating of `satisfactory record of meeting community credit needs', or better, at the most recent examination of such bank under the Community Reinvestment Act of 1977, ``(B) the outstanding local community loans of which at all times during the taxable year comprised not less than 60 percent of the total outstanding loans of that bank, ``(C) meets the ownership requirements of paragraph (3), and ``(D) at all times during the taxable year has total assets of not more than $1,000,000,000. ``(3) Ownership requirements.-- ``(A) In general.--The ownership requirements of this paragraph are met with respect to any bank if-- ``(i) no shares of, or other ownership interests in, the bank are publicly traded, or ``(ii) in the case of a bank the shares of which or ownership interests in which are publicly traded, the last known address of the holders of at least \2/3\ of all such shares or interests, including persons for whose benefit such shares or interests are held by another, is in the home State of the bank or a State contiguous to such home State. ``(B) Home state defined.--For purposes of subparagraph (A), the term `home State' means-- ``(i) with respect to a national bank or Federal savings association, the State in which the main office of the bank or savings association is located, and ``(ii) with respect to a State bank or State savings association, the State by which the bank or savings association is chartered. ``(4) Other definitions.--For purposes of this subsection-- ``(A) Bank.--The term `bank'-- ``(i) has the meaning given to such term in section 581, and ``(ii) includes any bank-- ``(I) in which at least 80 percent of the shares of, or other ownership interests in, the bank are owned by other qualified community lenders, and ``(II) the sole purpose of which is to serve the banking needs of such lenders. ``(B) Local community loan.--The term `local community loan' means-- ``(i) any loan originated by a bank to any person, other than a related person with respect to the bank, who is a resident of a community in which the bank is chartered or in which it operates an office at which deposits are accepted, and ``(ii) any loan originated by a bank to any person, other than a related person with respect to the bank, who is engaged in a trade or business in any such community, to the extent that all or substantially all of the proceeds of such loan are expended in connection with the trade or business of such person in any such community. ``(C) Related person.--The term `related person' means, with respect to any bank, any affiliate of the bank, any person who is a director, officer, or principal shareholder of the bank, and any member of the immediate family of any such person.''. (b) S Corporation Income.--Section 1 of the Internal Revenue Code of 1986 (relating to tax imposed) is amended by adding at the end the following: ``(j) Community Lender Income From S Corporation.-- ``(1) In general.--If a taxpayer has community lender income from a S corporation for any taxable year, the tax imposed by this section for such taxable year shall be the sum of-- ``(A) the tax computed at the rates and in the same manner as if this subsection had not been enacted on the greater of-- ``(i) taxable income reduced by community lender income, or ``(ii) the lesser of-- ``(I) the amount of taxable income taxed at a rate below 25 percent, or ``(II) taxable income reduced by community lender income, and ``(B) a tax on community lender income computed at-- ``(i) a rate of zero on zero-rate community lender income, ``(ii) a rate of 15 percent on 15 percent community lender income, and ``(iii) the highest rate in effect under this section with respect to the taxpayer on the excess of community lender income on which a tax is determined under clause (i) or (ii). ``(2) Community lender income.--For purposes of paragraph (1)-- ``(A) In general.--The term `qualified community lender income' means taxable income (if any) of a qualified community lender (as defined in section 11(d)(2)) that is an S corporation, determined at the entity level. ``(B) Zero-rate community lender income.--The term `zero-rate community lender income' means the taxpayer's pro rata share of so much of community lender income as does not exceed $250,000. ``(C) 15 percent community lender income.--The term `15 percent community lender income' means the taxpayer's pro rata share of so much of community lender income as exceeds $250,000 but does not exceed $1,000,000. ``(D) Special rules.-- ``(i) For purposes of this paragraph, the taxpayer's pro rata share of community lender income shall be determined under part II of subchapter S. ``(ii) This subsection shall be applied after the application of subsection (h).''. (c) Effective Date.--The amendments made by this section shall apply to taxable years beginning after December 31, 2003. SEC. 3. EXCLUSION FROM INCOME TAXATION FOR INCOME DERIVED FROM BANKING SERVICES WITHIN DISTRESSED COMMUNITIES. (a) In General.--Part III of subchapter B of chapter 1 of the Internal Revenue Code of 1986 (relating to items specifically excluded from gross income) is amended by inserting after section 140A the following new section: ``SEC. 140B. BANKING SERVICES WITHIN DISTRESSED COMMUNITIES. ``(a) In General.--At the election of the taxpayer, gross income shall not include distressed community banking income. ``(b) Distressed Community Banking Income.--For purposes of subsection (a), the term `distressed community banking income' means net income of a qualified depository institution which is derived from the active conduct of a banking business in a distressed community. ``(c) Qualified Depository Institution.--For purposes of this section, an institution is a qualified depository institution if-- ``(1) such institution is an insured depository institution (as defined in section 3 of the Federal Deposit Insurance Act (12 U.S.C. 1813)), ``(2) such institution is located in, or has a branch located in, a qualified distressed community, and ``(3) as of the last day of the taxable year, at least 85 percent of its loans from its location within the qualified distressed community are local community loans (as defined in section 11(d)(4)(B)). ``(d) Distressed Community.--For purposes of this section, the term `distressed community' has the meaning given the term `qualified distressed community' by section 233 of the Bank Enterprise Act of 1991 (12 U.S.C. 1834a(b)).''. (b) Clerical Amendment.--The table of sections for part III of subchapter B of chapter 1 of the Internal Revenue Code of 1986 is amended by inserting after the item relating to section 140A the following: ``Sec. 140B. Banking services within distressed communities.''. (c) Effective Date.--The amendments made by this section shall apply to taxable years beginning after the date of the enactment of this Act.

Community Savings and Investment Act of 2004 - Amends the Internal Revenue Code to establish a separate corporate income tax rate for qualified community lenders of: (1) 15 percent of the amount of taxable income over $250,000 up to $1 million; and (2) the highest corporate tax rate imposed (currently 35%) for income over $1 million. Defines "qualified community lender" as a local community bank which: (1) achieved a satisfactory record of meeting community credit needs at its most recent Federal bank examination: (2) provided not less than 60 percent of its loans to its local community; (2) meets specified community ownership requirements; and (4) has total assets of not more than $1 billion. Reduces tax rates on certain subchapter S taxable income attributable to community lender income. Excludes from gross income distressed community banking income. Defines "distressed community banking income" as the net income of an FDA-insured bank which is derived from the active conduct of a banking business in a low-income, high unemployment community as defined by the Bank Enterprise Act of 1991.

swimming requires muscle strength , as the arms perform the power to swing by water . master level swimmers might use the overhead shoulder joint position up to 11,000 or more times in one week of training1 . swimming requires the repetitive nature of movements that can frequently lead to soft tissue micro - trauma in the shoulder joint2 , 3 . in addition , imbalance of muscle strength and flexibility loss has been implicated in shoulder joint injuries4 ; a major reason for the loss of time in training5 . other reports recognize that swimmers experience many back problems6 , 7 . as one s arms swing in the water , the trunk provides a stable platform for the arm and leg motions , as evidenced by high electromyographic ( emg ) muscle activity recorded in the back and abdominal muscles during swimming8 . these studies demonstrate the association between physical functions and the difference in swimming performance levels , the status of training experience , and age9,10,11 . swimmers of a young age have high muscle strength and aerobic capacity than non - swimmers of a comparable age . in additional , swimmers of a young age had properly weight of body and fat - free mass and percent of body fat than older swimmers9,10,11 . there are no reports on the aerobic capacity of swimmers according to swimming levels . the relationship between basic physical fitness , isokinetic strength , and aerobic capacity in swimmers remains imprecise12 , 13 . therefore , the purpose of this study was to compare basic physical fitness , aerobic capacity , and isokinetic strength between international and national level freestyle high school swimmers . we included a total of 28 participants ( 14 international level swimmers and 14 national level freestyle high school swimmers ) with no known pathology in the study . we excluded those who were on any medication or likely to take any medication during the study period . all participants gave informed consent according to the method outlined by the institutional review board before study participation . all participants underwent an evaluation of basic physical fitness , isokinetic strength , and aerobic capacity . following the evaluation , these three variables were compared between the international level swimmers and national level swimmers . body composition was analyzed using a portable eight - polar tactile - electrode impedancio - meter ( inbody 3.0 , biospace , gateshead , uk ) . this device was used to measure height ( cm ) , weight ( kg ) , fat mass ( % ) , skeletal muscle mass ( kg ) , and body mass index ( bmi ) ( kg / m ) . we performed the measurements under the following conditions : at least two hours after the last meal , without clothes on , without any metallic objects on the body , and after remaining in a standing position for a minimum of five minutes before the test . evaluation of physical fitness was performed using helmas 2.0 ( o2 run , inc . , concerning muscular endurance , the number of sit - ups performed in 30 seconds was assessed . for testing agility , a standing high jump was performed twice ; we recorded the higher score . trunk flexibility was tested with the sit and reach movement performed twice , during which we assessed the range of the forward movement of the trunk . peak torques in the shoulder , lumbar , and knee joints were measured to assess isokinetic muscle strength using the humac / norm cybex ( csmi ) 770 dynamometer . we repeated the isokinetic strength test three times ; we recorded the peak torque as the participant s strength . we adopted low angular velocities ( 60/second ) to measure concentric isokinetic strength14 , 15 . the sub - maximal graded exercise treadmill test consisted of a real - time recording 12-channel electrocardiography ( q5000 , quinton instrument co. , boston , ma , usa ) , a respiratory gas analyzer ( qmc , quinton instrument co. ) , an automatic blood pressure and pulse monitor ( model 412 , quinton instrument co. ) , and a treadmill ( medtrack st 55 , quinton instrument co. ) for evaluating aerobic capacity . the investigator evaluated the exercise heart rate ( hr ) and rating of perceived exertion ( rpe ) score at the end of each stage . we assessed the maximal oxygen uptake ( vo2max ) through a respiratory gas analyzer16 . the results are shown using descriptive statistics : mean and standard deviation ( sd ) . for variables with a normal distribution , the independent t - test was used for comparison between the two groups . chicago , il , usa ) . in all cases , the level of significance was set at p < 0.05 . the mean age , weight , height , bmi , fat - free mass , body fat mass , body muscle mass , and body fat % distribution of the international level swimmers and national level swimmers were not significantly different ( table 1table 1.general characteristics and body composition of the participantsvariableinternational swimmersnational swimmersmean sdmean sdage ( years)16.8 0.817.4 0.8height ( cm)177.4 3.7175.5 3.1weight ( kg)73.7 6.469.9 3.2bmi ( kg / m)23.4 1.322.7 0.7bfm ( kg)10.7 1.910.3 0.8lbm ( kg)63.0 4.860.7 3.3muscle mass ( kg)59.4 4.557.2 3.2bfp ( % ) 13.4 1.713.3 1.3no significant difference between both the groups . bmi : body mass index , bfm : body fat mass , lbm : lean body mass , bfp : body fat percentage ) . bmi : body mass index , bfm : body fat mass , lbm : lean body mass , bfp : body fat percentage the mean values of the strength of the back muscles , sit - ups , standing high jumps , and sit and reach movement in the international level swimmers were significantly higher than those in the national level swimmers ( p<0.05 ) ( table 2table 2.general characteristics and body composition of the participantsvariableinternational swimmersnational swimmersmean sdmean sdback muscle strength ( kg)150.0 9.5139.1 8.1*sit - up ( frequency)30.4 3.627.0 2.6*standing high jump ( cm)58.3 7.752.6 6.9*sit & reach ( cm)21.6 4.218.1 4.0**p < 0.05 , significantly difference between both the groups ) . * p < 0.05 , significantly difference between both the groups the international level swimmers scored higher on the peak torque in the shoulder joint , lumbar spine , and knee joint than the national level swimmers ; there was a significant difference in trunk extension , knee extension , and internal and external shoulder rotation between the groups ( p < 0.05 ) ( table 3table 3.comparison of isokinetic strength of trunk , knee , and shoulder between both the groupsvariableinternational swimmersnational swimmersmeansdmeansdpeak torque ( ft - lbs)trunkflexion137.213.3127.011.8 extension147.314.1135.512.5*kneeright flexion97.310.591.09.3 extension146.516.0132.515.2*left flexion95.18.287.49.4 extension142.616.2130.414.6*shoulderrightinternal rotation110.212.498.710.1*external rotation78.69.370.08.2*leftinternal rotation103.910.393.28.3*external rotation74.79.865.08.0**p < 0.05 , significantly difference between the both groups ) . * p < 0.05 , significantly difference between the both groups the mean values of the vo2max , vo2max % , and body weight in the international level swimmers were significantly higher than those in the national level swimmers ( p < 0.05 ) ( table 4table 4.comparison of aerobic capacity between both the groupsvariableinternational swimmersnational swimmersmeansdmeansdvo2max ( ml / min)4,244.0591.03,722.1587.1vo2max % body weight(ml / min / kg)57.65.853.24.9vo2max : maximal oxygen uptake , * p < 0.05 , significantly difference between both the groups ) . vo2max : maximal oxygen uptake , * p < 0.05 , significantly difference between both the groups swimming involves complicated , coordinated , high muscle fiber contractions , with 40200 or more repetitions17 . the positive relationship between muscle strength , vo2max , and stroke length are important observations made in previous studies . therefore , the purpose of this study was to compare basic physical fitness , aerobic capacity , and isokinetic strength between international level swimmers and national level swimmers . swimmers usually focus on improving performance by optimizing their swimming technique rather than increasing their muscle strength21 , 24 , 25 . in our study , the mean values of basic physical fitness and isokinetic strength in the international level swimmers were higher than those in the national level swimmers . the associations among basic physical fitness , muscle strength , and performance become more evident at high swimming velocities , specifically in shorter duration competitions21 , 24 , 25 . showed an increase in strength of shoulder rotators in swimmers compared with that in non - swimmers5 . additionally , the trunk position controls an important role in supplying a stable platform from which the low and upper extremities can conduct powerful motions10 . emg data confirms that the rectus abdominis is one of the muscles most accountable for propulsion through swimming10 . moreover , emg activity in the back and abdominal muscles is higher in competitive swimmers than in non - competitive swimmers during freestyle swimming10 . the international level swimmers scored higher than the national level swimmers on the peak torque in vo2max and vo2max % body weight in our study . vo2max in absolute and relative terms was significantly higher in the trained group compared to the untrained group . we expected this as swimming is an aerobic exercise that greatly taxes the oxygen transport system . this kind of training augments vo2max and , therefore , improves physical fitness16 , 26 . vo2max values were 31.5% higher , and the relative values were approximately 20% higher in the trained group compared to the untrained group ; this was considered significant in previous studies16 , 26 . in conclusion , freestyle swimmers are generally physically fit and seem to have a good competition record . therefore , there is a need to consistently evaluate the physical performance of freestyle swimmers using a variety of assessment devices . in addition to this , an appropriate training program , which considers specific individual characteristics , is likely to have a positive impact on the improvement of physical fitness , and subsequently , on the performance of the freestyle swimmers .

[ purpose ] this study aimed to compare basic physical fitness , aerobic capacity , and isokinetic strength between international and national level freestyle high school student swimmers . [ subjects and methods ] a total of 28 participants ( 14 international level swimmers and 14 national level freestyle high school student swimmers ) with no known pathology were included . we used a cross - sectional study to examine three variables : basic physical fitness , aerobic capacity , and isokinetic strength . [ results ] the mean values of these variables in the international level swimmers were higher than those in the national level swimmers . swimmers are generally physically fit with a good competition record . [ conclusion ] an appropriate training program , which considers specific individual characteristics is likely to have a positive impact on the improvement of total physical fitness , and subsequently , on the performance of the freestyle high school swimmer .

SECTION 1. SHORT TITLE. This Act may be cited as the ``Long-Term Care Affordability and Security Act of 2007''. SEC. 2. TREATMENT OF PREMIUMS ON QUALIFIED LONG-TERM CARE INSURANCE CONTRACTS. (a) In General.-- (1) Cafeteria plans.--The last sentence of section 125(f) of the Internal Revenue Code of 1986 (defining qualified benefits) is amended by inserting before the period at the end ``; except that such term shall include the payment of premiums for any qualified long-term care insurance contract (as defined in section 7702B) to the extent the amount of such payment does not exceed the eligible long-term care premiums (as defined in section 213(d)(10)) for such contract''. (2) Flexible spending arrangements.--Section 106 of such Code (relating to contributions by an employer to accident and health plans) is amended by striking subsection (c) and redesignating subsection (d) as subsection (c). (b) Conforming Amendments.-- (1) Section 6041 of such Code is amended by adding at the end the following new subsection: ``(h) Flexible Spending Arrangement Defined.--For purposes of this section, a flexible spending arrangement is a benefit program which provides employees with coverage under which-- ``(1) specified incurred expenses may be reimbursed (subject to reimbursement maximums and other reasonable conditions), and ``(2) the maximum amount of reimbursement which is reasonably available to a participant for such coverage is less than 500 percent of the value of such coverage. In the case of an insured plan, the maximum amount reasonably available shall be determined on the basis of the underlying coverage.''. (2) The following sections of such Code are each amended by striking ``section 106(d)'' and inserting ``section 106(c)'': sections 223(b)(4)(B), 223(d)(4)(C), 223(f)(3)(B), 3231(e)(11), 3306(b)(18), 3401(a)(22), 4973(g)(1), and 4973(g)(2)(B)(i). (3) Section 6041(f)(1) of such Code is amended by striking ``(as defined in section 106(c)(2))''. (c) Effective Date.--The amendments made by this section shall apply to taxable years beginning after December 31, 2006. SEC. 3. ADDITIONAL CONSUMER PROTECTIONS FOR LONG-TERM CARE INSURANCE. (a) Additional Protections Applicable to Long-Term Care Insurance.--Subparagraphs (A) and (B) of section 7702B(g)(2) of the Internal Revenue Code of 1986 (relating to requirements of model regulation and Act) are amended to read as follows: ``(A) In general.--The requirements of this paragraph are met with respect to any contract if such contract meets-- ``(i) Model regulation.--The following requirements of the model regulation: ``(I) Section 6A (relating to guaranteed renewal or noncancellability), other than paragraph (5) thereof, and the requirements of section 6B of the model Act relating to such section 6A. ``(II) Section 6B (relating to prohibitions on limitations and exclusions) other than paragraph (7) thereof. ``(III) Section 6C (relating to extension of benefits). ``(IV) Section 6D (relating to continuation or conversion of coverage). ``(V) Section 6E (relating to discontinuance and replacement of policies). ``(VI) Section 7 (relating to unintentional lapse). ``(VII) Section 8 (relating to disclosure), other than sections 8F, 8G, 8H, and 8I thereof. ``(VIII) Section 11 (relating to prohibitions against post-claims underwriting). ``(IX) Section 12 (relating to minimum standards). ``(X) Section 13 (relating to requirement to offer inflation protection). ``(XI) Section 25 (relating to prohibition against preexisting conditions and probationary periods in replacement policies or certificates). ``(XII) The provisions of section 28 relating to contingent nonforfeiture benefits, if the policyholder declines the offer of a nonforfeiture provision described in paragraph (4) of this subsection. ``(ii) Model act.--The following requirements of the model Act: ``(I) Section 6C (relating to preexisting conditions). ``(II) Section 6D (relating to prior hospitalization). ``(III) The provisions of section 8 relating to contingent nonforfeiture benefits, if the policyholder declines the offer of a nonforfeiture provision described in paragraph (4) of this subsection. ``(B) Definitions.--For purposes of this paragraph-- ``(i) Model regulation.--The term `model regulation' means the long-term care insurance model regulation promulgated by the National Association of Insurance Commissioners (as adopted as of December 2006). ``(ii) Model act.--The term `model Act' means the long-term care insurance model Act promulgated by the National Association of Insurance Commissioners (as adopted as of December 2006). ``(iii) Coordination.--Any provision of the model regulation or model Act listed under clause (i) or (ii) of subparagraph (A) shall be treated as including any other provision of such regulation or Act necessary to implement the provision. ``(iv) Determination.--For purposes of this section and section 4980C, the determination of whether any requirement of a model regulation or the model Act has been met shall be made by the Secretary.''. (b) Excise Tax.--Paragraph (1) of section 4980C(c) of the Internal Revenue Code of 1986 (relating to requirements of model provisions) is amended to read as follows: ``(1) Requirements of model provisions.-- ``(A) Model regulation.--The following requirements of the model regulation must be met: ``(i) Section 9 (relating to required disclosure of rating practices to consumer). ``(ii) Section 14 (relating to application forms and replacement coverage). ``(iii) Section 15 (relating to reporting requirements). ``(iv) Section 22 (relating to filing requirements for marketing). ``(v) Section 23 (relating to standards for marketing), including inaccurate completion of medical histories, other than paragraphs (1), (6), and (9) of section 23C. ``(vi) Section 24 (relating to suitability). ``(vii) Section 27 (relating to the right to reduce coverage and lower premiums). ``(viii) Section 31 (relating to standard format outline of coverage). ``(ix) Section 32 (relating to requirement to deliver shopper's guide). The requirements referred to in clause (vi) shall not include those portions of the personal worksheet described in Appendix B relating to consumer protection requirements not imposed by section 4980C or 7702B. ``(B) Model act.--The following requirements of the model Act must be met: ``(i) Section 6F (relating to right to return). ``(ii) Section 6G (relating to outline of coverage). ``(iii) Section 6H (relating to requirements for certificates under group plans). ``(iv) Section 6J (relating to policy summary). ``(v) Section 6K (relating to monthly reports on accelerated death benefits). ``(vi) Section 7 (relating to incontestability period). ``(vii) Section 9 (relating to producer training requirements). ``(C) Definitions.--For purposes of this paragraph, the terms `model regulation' and `model Act' have the meanings given such terms by section 7702B(g)(2)(B).''. (c) Effective Date.--The amendments made by this section shall apply to policies issued more than 1 year after the date of the enactment of this Act.

Long-Term Care Affordability and Security Act of 2007 - Amends the Internal Revenue Code to: (1) include long-term care insurance as a benefit under tax-exempt employee benefit cafeteria plans and flexible spending arrangements; and (2) make certain consumer protections applicable to long-term care insurance.

SECTION 1. SHORT TITLE. This Act may be cited as the ``Education Improvement Tax Cut Act''. SEC. 2. CREDIT FOR CONTRIBUTIONS TO CHARITABLE ORGANIZATIONS WHICH PROVIDE ELEMENTARY OR SECONDARY SCHOOL SCHOLARSHIPS. (a) In General.--Subpart A of part IV of subchapter A of chapter 1 of the Internal Revenue Code of 1986 (relating to nonrefundable personal credits) is amended by inserting after section 25D the following new section: ``SEC. 25E. CONTRIBUTIONS TO ORGANIZATIONS PROVIDING ELEMENTARY OR SECONDARY SCHOOL SCHOLARSHIPS. ``(a) Allowance of Credit.--In the case of an individual, there shall be allowed as a credit against the tax imposed by this chapter for the taxable year an amount equal to the qualified scholarship contributions of the taxpayer for the taxable year. ``(b) Maximum Credit.--The credit allowed by subsection (a) for any taxable year shall not exceed $5,000 (one-half such amount in the case of a married individual (as determined under section 7703) filing a separate return). ``(c) Qualified Scholarship Contribution.--For purposes of this section-- ``(1) In general.--The term `qualified scholarship contribution' means, with respect to any taxable year, the amount which would (but for subsection (d)) be allowable as a deduction under section 170 for cash contributions to a school tuition organization. ``(2) School tuition organization.-- ``(A) In general.--The term `school tuition organization' means any organization described in section 170(c)(2) if the annual disbursements of the organization for elementary and secondary school scholarships are normally not less than 90 percent of the sum of such organization's annual gross income and contributions and gifts. ``(B) Elementary and secondary school scholarship.--The term `elementary and secondary school scholarship' means any scholarship excludable from gross income under section 117 for expenses related to education at or below the 12th grade. ``(d) Denial of Double Benefit.--No deduction shall be allowed under this chapter for any contribution for which a credit is allowed under this section. ``(e) Election To Have Credit Not Apply.-- ``(1) In general.--A taxpayer may elect to have this section not apply for any taxable year. ``(2) Time for making election.--An election under paragraph (1) for any taxable year may be made (or revoked) at any time before the expiration of the 3-year period beginning on the last date prescribed by law for filing the return for such taxable year (determined without regard to extensions). ``(f) Cost-of-Living Adjustment.--In the case of any taxable year beginning in a calendar year after 2007, the dollar amount contained in subsection (b) shall be increased by an amount equal to-- ``(1) such dollar amount, multiplied by ``(2) the cost-of-living adjustment determined under section 1(f)(3) for the calendar year in which the taxable year begins, by substituting `calendar year 2006' for `calendar year 1992' in subparagraph (B) thereof. If any increase determined under the preceding sentence is not a multiple of $10, such increase shall be increased to the next highest multiple of $10. In the case of a married individual (as determined under section 7703) filing a separate return, the preceding sentence shall be applied by substituting `$5' for `$10' each place it appears. ``(g) Regulations.--The Secretary shall prescribe regulations to carry out this section, including regulations providing for claiming the credit under this section on Form 1040EZ.''. (b) Clerical Amendment.--The table of sections for subpart A of part IV of subchapter A of chapter 1 of such Code is amended by inserting after the item relating to section 25D the following new item: ``Sec. 25E. Contributions to organizations providing elementary or secondary school scholarships.''. (c) Effective Date.--The amendments made by this section shall apply to taxable years beginning after December 31, 2006. SEC. 3. CREDIT FOR CONTRIBUTIONS OF AND FOR INSTRUCTIONAL MATERIALS AND MATERIALS FOR EXTRACURRICULAR ACTIVITIES. (a) In General.--Subpart A of part IV of subchapter A of chapter 1 of the Internal Revenue Code of 1986 (relating to nonrefundable personal credits), as amended by this Act, is amended by inserting after section 25E the following new section: ``SEC. 25F. CONTRIBUTIONS OF AND FOR INSTRUCTIONAL MATERIALS AND MATERIALS FOR EXTRACURRICULAR ACTIVITIES. ``(a) Allowance of Credit.--In the case of an individual, there shall be allowed as a credit against the tax imposed by this chapter for the taxable year an amount equal to the qualified school materials contributions of the taxpayer for the taxable year. ``(b) Maximum Credit.--The credit allowed by subsection (a) for any taxable year shall not exceed $5,000 (one-half such amount in the case of a married individual (as determined under section 7703) filing a separate return). ``(c) Qualified School Materials Contribution.--For purposes of this section-- ``(1) In general.--The term `qualified school materials contribution' means, with respect to any taxable year, the amount which would (but for subsection (d)) be allowable as a deduction under section 170 for-- ``(A) any cash contribution to any elementary or secondary school if such contribution is designated to be used solely to acquire qualified school materials, ``(B) any contribution of qualified school materials to any elementary or secondary school, and ``(C) any cash contribution to a school materials organization. ``(2) Elementary or secondary school.--The term `elementary or secondary school' means any organization described in section 170(b)(1)(A)(ii) which provides education solely at or below the 12th grade. ``(3) School materials organization.-- ``(A) In general.--The term `school materials organization' means any organization described in section 170(c)(2) if-- ``(i) the primary function of the organization is to raise funds for elementary or secondary schools, and ``(ii) the annual disbursements of the organization for qualified school materials which are provided to elementary and secondary schools are normally not less than 90 percent of the sum of such organization's annual gross income and contributions and gifts. ``(B) Qualified school materials.--The term `qualified school materials' means-- ``(i) instructional materials and equipment, including library books and materials, computers, and computer software, and ``(ii) materials and equipment for school- sponsored extracurricular activities. ``(d) Denial of Double Benefit.--No deduction shall be allowed under this chapter for any contribution for which a credit is allowed under this section. ``(e) Election To Have Credit Not Apply.-- ``(1) In general.--A taxpayer may elect to have this section not apply for any taxable year. ``(2) Time for making election.--An election under paragraph (1) for any taxable year may be made (or revoked) at any time before the expiration of the 3-year period beginning on the last date prescribed by law for filing the return for such taxable year (determined without regard to extensions). ``(f) Cost-of-Living Adjustment.--In the case of any taxable year beginning in a calendar year after 2007, the dollar amount contained in subsection (b) shall be increased by an amount equal to-- ``(1) such dollar amount, multiplied by ``(2) the cost-of-living adjustment determined under section 1(f)(3) for the calendar year in which the taxable year begins, by substituting `calendar year 2006' for `calendar year 1992' in subparagraph (B) thereof. If any increase determined under the preceding sentence is not a multiple of $10, such increase shall be increased to the next highest multiple of $10. In the case of a married individual (as determined under section 7703) filing a separate return, the preceding sentence shall be applied by substituting `$5' for `$10' each place it appears. ``(g) Regulations.--The Secretary shall prescribe regulations to carry out this section, including regulations providing for claiming the credit under this section on Form 1040EZ.''. (b) Clerical Amendment.--The table of sections for subpart A of part IV of subchapter A of chapter 1 of such Code, as amended by this Act, is amended by inserting after the item relating to section 25E the following new item: ``Sec. 25F. Contributions of and for instructional materials and materials for extracurricular activities.''. (c) Effective Date.--The amendments made by this section shall apply to taxable years beginning after December 31, 2006.

Education Improvement Tax Cut Act - Amends the Internal Revenue Code to allow: (1) a tax credit up to $5,000 per year (adjusted annually for inflation after 2007) for contributions to a school tuition organization which distributes at least 90 percent of its annual gross income for elementary and secondary school scholarships; and (2) a tax credit up to $5,000 per year (adjusted annually for inflation after 2007) for contributions to a school materials organization which distributes at least 90 percent of its annual gross income to elementary and secondary schools for materials and equipment for instruction and for extracurricular activities.

diabetes mellitus is a very common long - term metabolic condition of older adults ; the global burden of the disease is increasing . the number of patients with type 2 diabetes is expected to increase from 381.8 million to 592.0 million worldwide from 2013 to 2035.1 in south korea , although age - standardized mortality rates have decreased over the past decade , type 2 diabetes remains the fifth leading cause of death,2 and south korea ranked fourth among oecd countries in terms of the diabetes mortality rate.3 in addition , the korea national health and nutrition examination survey ( knhanes ) revealed that the prevalence of diabetes mellitus increased from 8.6% in 2001 to 11.0% in 2013.4 type 2 diabetes is a complex disorder influenced by genetic , environmental , and nutritional factors . vitamin d is a steroid hormone that regulates bone and mineral metabolism by balancing the levels of calcium and phosphorus . many tissues express vitamin d receptors , suggesting that vitamin d plays physiological roles in a number of organs besides bone . in recent years , it has been suggested that vitamin d may influence several nonskeletal disorders such as cardiovascular disease , cancer , autoimmune disorders , hypertension and diabetes.5678 despite the importance of the vitamin for both skeletal and nonskeletal health , vitamin d deficiency remains a problem worldwide , being very prevalent both in developed countries and populous regions of asia , india , and the middle east . vitamin d deficiency is also very common in south korea.9 vitamin d may benefit type 2 diabetic patients by improving pancreatic -cell function , insulin action , and systemic inflammation.10 many observational studies have reported associations between the 25-hydroxyvitamin d [ 25(oh)d ] level ( the serum levels of which are often used to indicate vitamin d status ) and the risk of type 2 diabetes ; however , the data are inconsistent.101112 although vitamin d insufficiency is very common in korea,9 only two studies have explored the association between vitamin d levels and type 2 diabetes in korea.1314 therefore , the author investigated the association between serum 25(oh)d level and type 2 diabetes in urban korean adults . the author used data obtained during the dong - gu study , which is described in detail elsewhere.15 in brief , the dong - gu study is an ongoing , prospective population - based project exploring risk factors for chronic diseases such as cardiovascular disease , fracture , cognitive decline , and cancer in an elderly urban population . the baseline survey recruited 9,260 participants aged 50 years from 2007 to 2010 in the dong - gu district of gwangju ( a metropolitan city of south korea ) . after exclusion of subjects for whom data was missing , a total of 8,991 subjects ( 3,588 males and 5,403 females ) were included in the present study . the study was approved by the institutional review board of chonnam national university hospital , and carried out in accordance with the guidelines of the declaration of helsinki . information on medical history , demographics , and lifestyle characteristics was collected using interviewer - administered standardized questionnaires . subjects were categorized as current smokers or nonsmokers ( including ex - smokers ) and as nondrinkers or current drinkers . exercise was divided into irregular or regular based on the weekly frequencies of recreational and physical activity . body mass index ( bmi ) was calculated as weight ( kg ) divided by height ( m ) squared . blood pressure in the right upper arm was measured on three consecutive occasions at 1-min intervals using a mercury sphygmomanometer ( baumanometer ; wa baum co. , inc . , all blood pressure measurements were performed with the subject seated after having rested for at least 5 min . the levels of serum total cholesterol , high - density lipoprotein ( hdl ) cholesterol , triglycerides , and fasting blood glucose were measured via enzymatic methods on an automatic analyzer ( model 7600 ; hitachi ltd . , c - reactive protein ( crp ) levels were determined using a bn ii nephelometer ( dade behring , marburg , germany ) . levels were measured by high - performance liquid chromatography using the variant ii system ( bio - rad , hercules , ca , usa ) . 25(oh)d levels were determined by chemiluminescent microparticle immunoassay ( archtect i2000 , abbott , chicago , il , usa ) . the lower level of detection was 3.0 ng / ml . diabetes mellitus was defined as having a blood glucose level of 126 mg / dl or a hba1c level of 6.5% or current use of diabetes medication . the vitamin d status was categorized based on the serum 25(oh)d level as severely deficient ( < 10 ng / ml ) , deficient ( 10 to < 20 ng / ml ) , insufficient ( 20 to < 30 ng / ml ) , or sufficient ( 30 ng / ml).16 baseline characteristics were analyzed by the vitamin d status and compared using analysis of variance and the chi - squared test , as appropriate . multiple logistic regression was used to obtain odds ratios ( ors ) with 95% confidence intervals ( 95% cis ) for associations between vitamin d status and the risk of type 2 diabetes after adjusting for age , sex , the month of blood collection , bmi , smoking status , alcohol consumption status , performance of regular exercise , use of antihypertensive medication , use of dyslipidemia medication , systolic blood pressure ( sbp ) , diastolic blood pressure ( dbp ) , total cholesterol level , log - transformed triglyceride concentration , hdl cholesterol level , and log - transformed crp concentration . sensitivity analysis was performed by excluding participants taking antidiabetic medications to explore the effects of such drugs on the results . stata version 12 software was used for all calculations ( statacorp , college station , tx , usa ) . the author used data obtained during the dong - gu study , which is described in detail elsewhere.15 in brief , the dong - gu study is an ongoing , prospective population - based project exploring risk factors for chronic diseases such as cardiovascular disease , fracture , cognitive decline , and cancer in an elderly urban population . the baseline survey recruited 9,260 participants aged 50 years from 2007 to 2010 in the dong - gu district of gwangju ( a metropolitan city of south korea ) . after exclusion of subjects for whom data was missing , a total of 8,991 subjects ( 3,588 males and 5,403 females ) were included in the present study . the study was approved by the institutional review board of chonnam national university hospital , and carried out in accordance with the guidelines of the declaration of helsinki . information on medical history , demographics , and lifestyle characteristics was collected using interviewer - administered standardized questionnaires . subjects were categorized as current smokers or nonsmokers ( including ex - smokers ) and as nondrinkers or current drinkers . exercise was divided into irregular or regular based on the weekly frequencies of recreational and physical activity . body mass index ( bmi ) was calculated as weight ( kg ) divided by height ( m ) squared . blood pressure in the right upper arm was measured on three consecutive occasions at 1-min intervals using a mercury sphygmomanometer ( baumanometer ; wa baum co. , inc . , copiague , ny , usa ) fitted with a cuff of the appropriate size . all blood pressure measurements were performed with the subject seated after having rested for at least 5 min . the levels of serum total cholesterol , high - density lipoprotein ( hdl ) cholesterol , triglycerides , and fasting blood glucose were measured via enzymatic methods on an automatic analyzer ( model 7600 ; hitachi ltd . , c - reactive protein ( crp ) levels were determined using a bn ii nephelometer ( dade behring , marburg , germany ) . hemoglobin a1c levels were measured by high - performance liquid chromatography using the variant ii system ( bio - rad , hercules , ca , usa ) . 25(oh)d levels were determined by chemiluminescent microparticle immunoassay ( archtect i2000 , abbott , chicago , il , usa ) . the lower level of detection was 3.0 ng / ml . diabetes mellitus was defined as having a blood glucose level of 126 mg / dl or a hba1c level of 6.5% or current use of diabetes medication . the vitamin d status was categorized based on the serum 25(oh)d level as severely deficient ( < 10 ng / ml ) , deficient ( 10 to < 20 ng / ml ) , insufficient ( 20 to < 30 ng / ml ) , or sufficient ( 30 ng / ml).16 baseline characteristics were analyzed by the vitamin d status and compared using analysis of variance and the chi - squared test , as appropriate . multiple logistic regression was used to obtain odds ratios ( ors ) with 95% confidence intervals ( 95% cis ) for associations between vitamin d status and the risk of type 2 diabetes after adjusting for age , sex , the month of blood collection , bmi , smoking status , alcohol consumption status , performance of regular exercise , use of antihypertensive medication , use of dyslipidemia medication , systolic blood pressure ( sbp ) , diastolic blood pressure ( dbp ) , total cholesterol level , log - transformed triglyceride concentration , hdl cholesterol level , and log - transformed crp concentration . sensitivity analysis was performed by excluding participants taking antidiabetic medications to explore the effects of such drugs on the results . stata version 12 software was used for all calculations ( statacorp , college station , tx , usa ) . the general characteristics of the study participants by vitamin d status are shown in table 1 . the mean subject age was 65.28.2 years , and males constituted 39.9% of all subjects . the prevalence of type 2 diabetes was 21.3% as defined by a fasting blood glucose level of 126 mg / dl , an hba1c concentration of 6.5% , or self - reported current use of diabetes medication . the prevalence of severe vitamin d deficiency , deficiency , insufficiency , and sufficiency were 7.8% , 68.1% , 21.3% , and 2.8% , respectively . subjects with a sufficient vitamin d status were more likely to be male , highly educated , smokers , drinkers , and physically active . such subjects had significantly lower bmi , sbp , dbp , total cholesterol , triglycerides , hdl - cholesterol , and hba1c . the age- and sex - adjusted prevalences of type 2 diabetes by vitamin d status are presented in fig . these prevalences were 22.6% , 22.5% , 18.4% , and 12.7% for those with severely deficient , deficient , insufficient , and sufficient vitamin d levels , respectively . table 2 shows the findings of logistic regression analysis , revealing an association between vitamin d status and type 2 diabetes . higher serum 25(oh)d levels were significantly associated with a decreased risk of type 2 diabetes . in the age- and sex - adjusted model , compared with those who were vitamin d - deficient , subjects who were vitamin d - insufficient or -sufficient were at a reduced risk of type 2 diabetes [ or ( 95% ci)=0.78 ( 0.690.90 ) and 0.50 ( 0.350.71 ) , respectively ] . after further adjustment for cardiovascular risk factors , these associations were slightly attenuated but remained significant . compared with subjects who were vitamin d - deficient , those who were vitamin d - insufficient and -sufficient were at a decreased risk of type 2 diabetes [ or ( 95% cis)=0.82 ( 0.710.94 ) and 0.51 ( 0.350.74 ) , respectively ] . in sensitivity analyses excluding patients taking diabetic medication , similar results were found , except that subjects who were severely vitamin d - deficient tended to have a lower prevalence of type 2 diabetes than did those who were vitamin d - insufficient ( data no shown ) . in this population - based cross - sectional study , a good vitamin d status was associated with a significantly decreased risk of type 2 diabetes . in addition , this association persisted in subjects who were not taking diabetes medications . as far as we know , this is the largest study to explore such associations in korea . many observational studies of the association between the serum 25(oh)d level and the risk of diabetes have been conducted , but the results have been inconsistent.101112 in a meta - analysis of 11 prospective studies ( 4 positive and 7 negative ) , forouhi et al.11 found an inverse association between the 25(oh)d level and the incidence of type 2 diabetes . the combined relative risk ( 95% ci ) of type 2 diabetes when subjects in the highest and lowest quartiles of 25(oh)d levels were compared was 0.59 ( 0.520.67 ) . in a recent updated meta - analysis of 22 prospective studies,12 each fall of one standard deviation of the 25(oh)d concentration was associated with an increased risk of type 2 diabetes ( relative risk , 1.21 ; 95% ci , 1.161.27 ) . two studies on korean subjects revealed associations between low serum 25(oh)d levels and diabetes . in a korean cross - sectional study using data from the third knhanes , subjects with the lowest 25(oh)d level were at a 1.75-fold greater risk of diabetes than were those with the highest level.14 in another korean study on 1,080 participants with a 5-year follow - up , 25(oh)d - deficiency was associated with a 3.4-fold greater risk of diabetes than that in subjects with sufficient 25(oh)d.13 although many observational studies have thus found that low serum 25(oh)d levels are associated with an increased risk of type 2 diabetes , any cause - and - effect relationship remains unclear . randomized controlled trials ( rcts ) , which minimize bias and confounding , are considered to be more definitive.17 however , in contrast to the results of many observational studies , rcts have revealed no effect of vitamin d supplementation on the incidence of type 2 diabetes 5 . in the women s health initiative trial , vitamin d supplementation was not associated with the risk of diabetes in a follow - up period of 7 years.18 avenell et al . performed a community - based trial assessing bone outcomes and found that vitamin supplementation did not change the risk of self - reported type 2 diabetes.19 in addition , a recent study used a mendelian randomization approach to explore whether the association between 25(oh)d levels and the risk of type 2 diabetes was causal.12 such randomization employs genetic variants that influence disease status as instrumental variables to identify causal relationships between an exposure and associated outcomes.20 genetically low 25(oh)d levels were not associated with the risk of type 2 diabetes . therefore , given this negative finding and those of rcts , the associations noted in observational studies ( including the present study ) are unlikely to reflect any causal relationship . in the present study , the vitamin d sufficient group had lower bmi , blood pressure , total cholesterol , triglyceride and hdl cholesterol than the vitamin d deficient group . after adjusting for age and gender , there was still a difference between the deficiency and sufficiency groups at all levels except for hdl cholesterol ( data not shown ) . similar to our study , in a meta - study,21 serum 25(oh)d levels showed an inverse weak correlation with bmi . in addition , in a bidirectional mendelian randomization study,22 the bmi allele score was associated with lower vitamin d levels , but the vitamin d allele scores were not associated with bmi . the study suggests that high bmi can lead to vitamin d deficiency , but vitamin deficiency does not cause obesity . although many observational studies have shown that low vitamin d concentrations were associated with high blood pressure and cholesterol levels , in clinical trials , vitamin d supplementation did not lower cholesterol levels and blood pressure.2324 therefore , it is unclear whether the relationships found in observational studies are causal . the strengths of our study are the population - based design and the relatively large sample size , which minimize selection bias and afford good statistical strength . however , several limitations are apparent . first , because this study is a cross - sectional study , the inverse association noted may be attributable to reverse causation or residual confounding . second , serum 25(oh)d concentrations were measured only once and therefore may not reflect the long - term vitamin d status . third , no data on sun exposure , the use of sunscreen , or dietary or vitamin d supplementation were available . fourth , the baseline survey of the cohort study was conducted on voluntary participants in a community , with a response rate of 27.2% . therefore , this study can not be seen as representative of koreans . in conclusion , we found that a good vitamin d status was associated with a decreased risk of type 2 diabetes in korean urban adults , suggesting that serum vitamin d may play a role in the pathogenesis of diabetes .

previous studies have suggested that a vitamin d deficiency increases the risk of type 2 diabetes . this study evaluated the association between serum vitamin d levels and type 2 diabetes in korean adults . this study included 9,014 subjects ( 3,600 males and 5,414 females ) aged 50 years who participated in the dong - gu study . the subjects were divided into groups in whom the serum vitamin d level was severely deficient ( < 10 ng / ml ) , deficient ( 10 to < 20 ng / ml ) , insufficient ( 20 to < 30 ng / ml ) and sufficient ( 30 ng / ml ) . type 2 diabetes was defined by a fasting blood glucose level of 126 mg / dl and/or an hba1c proportion of 6.5% and/or self - reported current use of diabetes medication . multiple logistic regression was performed to evaluate the association between vitamin d status and type 2 diabetes . the age- and sex - adjusted prevalence of type 2 diabetes was 22.6% , 22.5% and 18.4% and 12.7% for severely deficient , deficient , insufficient , and sufficient , respectively . multivariate modeling revealed that subjects with insufficient or sufficient vitamin d levels were at a lower risk of type 2 diabetes than were subjects with deficient vitamin d levels [ odds ratio ( or ) , 0.82 ; 95% confidence interval ( ci ) , 0.710.94 and or , 0.51 ; 95% ci , 0.350.74 , respectively ] . higher serum vitamin d levels were associated with a reduced risk of diabetes in korean adults , suggesting that vitamin d may play a role in the pathogenesis of diabetes .

it is known that decoherence is one of the most important obstacles in quantum information processing , since it causes a quantum computer to lose its quantum properties destroying its performance advantages over a classical computer . there are different methods for preserving quantum coherence . one possible technique exploits redundancy in encoding information . as pointed out in @xcite , one might think that redundancy can not be of any use in quantum computing , since quantum states can not be cloned @xcite . however , using the property of quantum entanglement , shor and steane discovered a clever scheme for exploiting redundancy @xcite . this scheme is known as _ quantum error correcting codes _ ( qeccs ) . for a comprehensive introduction to qeccs , we refer to @xcite . within such scheme , information is encoded in linear subspaces ( codes ) of the total hilbert space in such a way that errors induced by the interaction with the environment can be detected and corrected . the qeccs approach may be interpreted as an active stabilization of a quantum state in which , by monitoring the system and conditionally carrying on suitable operations , one prevents the loss of information . in detail , the errors occur on a qubit when its evolution differs from the ideal one . this happens by interaction of the qubit with an environment . among the first and most famous qeccs , there are the shor nine - qubit code @xcite , the calderbank - shor - steane seven - qubit code @xcite and the perfect @xmath0-error correcting five - qubit code @xcite with transmission rate equal to @xmath1 . in general , scientists aim at searching for new quantum codes capable of combatting very general error models and correcting for arbitrary errors at unknown positions in the codeword . these results , in general , have more theoretical than practical importance , since they assume the existence of a fairly sophisticated quantum computer which has not been built yet . fortunately , in many realistic situations , additional information on possible errors is available . ideally , this knowledge should be taken into consideration in order to construct the simplest code with the highest transmission rate that can have a good chance to be implemented in a real laboratory . we stress _ ideally _ since , in general , it is a difficult problem to design quantum codes for any particular noise model . for instance , there are quantum systems for which the noise leads to dephasing errors only or bit - flip errors only . it has been shown that for such restricted types of decoherence , it is possible to perform error correction of one arbitrary dephasing / bit - flip error by encoding a single logical qubit into a minimum of three physical qubits @xcite . furthermore , uncovering efficient codes for restricted error models may be important for proof of principle demonstrations of quantum error correction @xcite . consider an error model where the position of the erroneous qubits is known . such errors at known positions are denoted as _ erasures _ @xcite__. _ _ a @xmath2-error correcting code is a @xmath3-erasure correcting code . also , while @xmath1 is the highest rate for a @xmath0-error correcting code , four qubits are sufficient for a code to correct one arbitrary erasure . omitting suitable normalization factors , the perfect four - qubit code for the correction of one erasure reads @xcite,@xmath4 in general , when no knowledge on the noise model is assumed , the errors to be corrected are completely random . this scenario may lead to the error correction of pauli - type errors @xmath5 , @xmath6 , @xmath7 ( with @xmath8 , @xmath9 , @xmath10 that occur with equal probability @xmath11 ( symmetric depolarizing channel , @xcite ) . however , if further information about an error process is available , more efficient codes can be designed as pointed out earlier . as a matter of fact , in many physical systems , the types of noise are likely to be unbalanced between amplitude ( @xmath5-type ) and phase ( @xmath7-type ) errors . these are asymmetric error models which are still described by kraus operators that are ( unitary ) pauli matrices ( pauli kraus operators ) . however , there are types of noise models seen in realistic settings that are not described by pauli kraus operators and , for these cases as well , the task of constructing good error correcting codes is very challenging . the amplitude damping ( ad ) channel is the simplest nonunital channel whose kraus operators can not be described by ( unitary ) pauli operations @xcite . the two kraus operators for ad noise are given by @xmath12 and @xmath13 where @xmath14 denotes the damping rate ( or , damping probability parameter ) . as we may observe , there is no simple way of reducing @xmath15 to one pauli error operator since @xmath16 is not normal . observe that @xmath17 , therefore the linear span of @xmath15 and @xmath18 equals the linear span of @xmath19 and @xmath20 . if the quantum system interacts with an environment at finite temperature , the kraus operator @xmath18 will appear in the noise model ( as stressed in @xcite , the error space to be corrected is a subspace of that spanned by the interaction operators , selected by the initial state of the environment ) @xcite . therefore , if a code is capable of correcting @xmath2 @xmath19- and @xmath2 @xmath20-errors , it can also correct @xmath2 @xmath15 and @xmath2 @xmath18 errors . for the ad channel , we only need to deal with the error @xmath15 but not with @xmath18 . for such a reason , requiring to be capable of correcting both @xmath19- and @xmath20-errors is a less efficient way for constructing quantum codes for the ad channel . the first quantum code correcting single - ad errors was a @xmath21 \right ] $ ] code presented by leung et _ al_. in @xcite . omitting proper normalization factors , the leung et _ @xmath22 \right ] $ ] code reads,@xmath23 the four - qubit code spanned by the codewords @xmath24 and @xmath25 in eq . ( [ leung ] ) represents a departure from standard qeccs that seek to _ perfectly _ correct up to @xmath2 arbitrary errors on the system . the key - point advanced in @xcite is that exact correctability is too strong a restriction . relaxing the knill - laflamme qec conditions ( kl - conditions ) @xcite in such a manner that they are only _ approximately _ satisfied and allowing for a negligible error in the recovery scheme , better codes with higher transmission rates can be uncovered . the adaptation of the code to the noise model , an idea remarked later also in @xcite , is a crucial factor behind the success of the leung et _ al_. four - qubit code . following the lead of @xcite , other works concerning the error correction of amplitude damping errors have appeared into the literature @xcite . in @xcite , it is emphasized that the concept of self - complementarity is crucial for error correcting amplitude damping errors , although the sel - complementarity of the leung et _ al_. code is not specifically mentioned . in @xcite , the performance of various quantum error correcting codes for ad errors are numerically analyzed . in particular , a numerical analysis of the performance ( quantified by means of schumacher s entanglement fidelity , @xcite ) of the four - qubit code for two recovery schemes can be found . the recovery schemes employed are the so - called code projected and the optimal channel adapted recovery schemes . the latter scheme was computed via semidefinite programming methods in @xcite . however , no explicit analytical investigation ( similar , for instance , to the investigations presented in @xcite and @xcite for depolarizing and weyl unitary errors , respectively ) is available . furthermore , as pointed out in @xcite , numerically computed recovery maps are difficult to describe and understand analytically . inspired by @xcite , we uncover that among the possible @xmath26-pairs of orthonormal self - complementary codewords in @xmath27 , only three pairs are indeed good ( locally permutation equivalent , @xcite ) single ad - error correcting codes . in particular , two of these pairs define the perfect @xmath0-erasure correcting code in eq . ( [ markus ] ) and the well - known four - qubit leung et _ al_. code in eq . ( [ leung ] ) . moreover , motivated by the numerical analysis presented in @xcite , we provide a fully analytical investigation of the performances , quantified in terms of schumacher s entanglement fidelity , of the leung et _ al_. four - qubit code . for the four - qubit code , the performance is evaluated for three different recovery schemes : the standard qec recovery operation , the code - projected recovery operation and , finally , an analytically - optimized fletchers - type channel - adapted recovery operation @xcite . the layout of this article is as follows . in section ii , we describe necessary conditions for approximate quantum error correction together with necessary and sufficient conditions for exact quantum error correction . in section iii , we present a detailed study for the exact error correction of the bit - flip ( or , similarly , phase - flip ) noise errors by means of the three - qubit repetition code . we also present an analytical investigation of amplitude errors by means of the leung et _ al_. four - qubit code . the performance of each code is quantified by means of the entanglement fidelity . in particular , we compare three different recovery schemes in the approximate case . the concluding remarks appear in section iv . a number of appendices with technical details of calculations are also provided . the very first _ sufficient conditions _ for approximate quantum error correction were introduced by leung et _ al_. in @xcite . they showed that quantum codes can be effective in the error correction procedure even though they violated the standard kl - conditions . however , these violations characterized by small deviations from the standard error - correction conditions are allowed provided that they do not affect the desired fidelity order . for the sake of reasoning , let us consider a quantum stabilizer code @xmath28 with code parameters @xmath29 \right ] $ ] encoding @xmath30-logical qubits in the hilbert space @xmath31 into @xmath32-physical qubits in the hilbert space @xmath33 and distance @xmath34 . assume that the noise model after the encoding procedure is @xmath35 and can be described by an operator - sum representation,@xmath36 where @xmath37 is the index set of all the enlarged kraus operators @xmath38 that appear in the sum . the noise channel * * @xmath39 * * is a cptp ( completely * * positive and trace preserving ) map . the codespace of @xmath28 is a @xmath30-dimensional subspace of @xmath33 where some error operators that characterize the error model @xmath39 being considered can be reversed . denote with @xmath40 @xmath41 with @xmath42 the set of reversible enlarged errors @xmath38 on @xmath28 such that @xmath43 is the index set of @xmath44 . therefore , the noise model @xmath45 given by,@xmath46 is reversible on @xmath47 . the noise channel * * @xmath48 * * denotes a cp but non - tp map . the enlarged error operators @xmath38 in @xmath44 satisfy the standard error correction conditions @xcite,@xmath49 for any @xmath50 , @xmath51 , @xmath52 denotes the projector on the codespace and @xmath53 are entries of a positive hermitian matrix . furthermore , a subset of error operators @xmath38 in @xmath44 is detectable if it satisfies the following detectability conditions , @xmath54 where @xmath55 denotes a proportionality constant between @xmath56 and @xmath52 . the fulfillment of eq . ( [ vai ] ) for some subset of enlarged error operators @xmath38 that characterize the operator sum representation of the noise model @xmath39 implies that there exists an new operator - sum decomposition of @xmath39 such that @xmath45 in eq . ( [ g1 ] ) becomes,@xmath57 where ( [ vai ] ) is replaced by@xmath58 for any @xmath50 , @xmath59 with the error detection probabilities @xmath60 non - negative @xmath61-numbers . we remark that eq . ( [ vai2 ] ) is equivalent to the usual ( exact ) orthogonality and non - deformation conditions for a nondegenerate code,@xmath62 for any @xmath63 , @xmath64 labelling the logical states and @xmath50 , @xmath51 . observe that for any linear operator @xmath65 on a vector space @xmath66 there exists a unitary @xmath67 and a positive operator @xmath68 such that @xcite,@xmath69 we stress that @xmath70 is the unique positive operator that satisfies eq . ( [ pd ] ) . as a matter of fact , multiplying @xmath71 on the left by the adjoint equation @xmath72 gives,@xmath73 furthermore , if @xmath65 is invertible ( that is , @xmath74 ) , @xmath67 is unique and * * reads,@xmath75 how do we choose the unitary @xmath67 when @xmath65 is not invertible ? the operator @xmath70 is a positive operator and belongs to a special subclass of hermitian operators such that for any vector @xmath76 , @xmath77 is a _ real _ and non - negative number . therefore , @xmath70 has a spectral decomposition@xmath78 where @xmath79 and @xmath80 denotes an orthonormal basis for the vector space @xmath66 . define the vectors @xmath81 and notice that,@xmath82 for the time being , consider only those @xmath50 for which @xmath83 . for those @xmath50 , consider the vectors @xmath84 defined as@xmath85 with @xmath86 . for those @xmath50 for which @xmath87 , extend the orthonormal set @xmath88 in such a manner that it forms an orthonormal basis @xmath89 . then , a suitable choice for the unitary operator @xmath67 such that@xmath90 with @xmath80 an orthonormal basis for @xmath66 reads,@xmath91 in summary , the unitary @xmath67 is uniquely determined by eq . ( [ ai ] ) when @xmath65 is invertible or eq . ( [ ani ] ) when @xmath65 is not necessarily invertible . we finally stress that the non - uniqueness of @xmath67 when @xmath92 is due to the freedom in choosing the orthonormal basis @xmath80 for the vector space @xmath66 . in the scenario being considered , when eq . ( [ vai2 ] ) is satisfied , the enlarged error operators @xmath93 admit polar decompositions,@xmath94 with @xmath95 . from eqs . ( [ vai2 ] ) and ( [ pd1 ] ) , we get@xmath96 that is,@xmath97 we stress that eq . ( [ condo ] ) is needed for an unambiguous syndrome detection since , as a consequence of the orthogonality of different @xmath98 , the recovery operation @xmath99 is trace preserving . this can be shown as follows . let @xmath100 be the subspace of @xmath33 spanned by the corrupted images @xmath101 of the codewords @xmath102 . let @xmath103 be an orthonormal basis for @xmath100 . we define such a subspace @xmath100 for each of the codewords . because of the kl - conditions @xcite,@xmath104 the subspaces @xmath100 and @xmath105 with @xmath106 are orthogonal subspaces . if @xmath107 is a proper subset of @xmath33 with @xmath108 , we denote its orthogonal complement by @xmath109 . we then have,@xmath110 where,@xmath111 let @xmath112 be an orthonormal basis for @xmath109 . then , the set of states @xmath113 constitutes an orthonormal basis for @xmath33 . we introduce the quantum recovery operation @xmath114 with operation elements@xmath115 with,@xmath116 where,@xmath117 and @xmath118 ( with @xmath119 ) is a projector onto the subspace @xmath109 in eq . ( [ deo]),@xmath120 we remark that the recovery operation @xmath114 is a trace preserving quantum operation by construction because,@xmath121 + \left ( \sum _ { k}\left\vert o_{k}\right\rangle \left\langle o_{k}\right\vert \right ) ^{\dagger}\left ( \sum_{k^{\prime}}\left\vert o_{k^{\prime}}\right\rangle \left\langle o_{k^{\prime}}\right\vert \right ) \nonumber\\ & \nonumber\\ & = \sum_{r\text { , } i\text { , } j}\left\vert v_{r}^{i_{l}}\right\rangle \left\langle i_{l}|j_{l}\right\rangle \left\langle v_{r}^{j_{l}}\right\vert + \sum_{k\text { , } k^{\prime}}\left\vert o_{k}\right\rangle \left\langle o_{k}|o_{k^{\prime}}\right\rangle \left\langle o_{k^{\prime}}\right\vert \nonumber\\ & \nonumber\\ & = \sum_{r\text { , } i\text { , } j}\left\vert v_{r}^{i_{l}}\right\rangle \left\langle v_{r}^{j_{l}}\right\vert \delta_{ij}+\sum_{k\text { , } k^{\prime}}\left\vert o_{k}\right\rangle \left\langle o_{k^{\prime}}\right\vert \delta_{kk^{\prime}}\nonumber\\ & \nonumber\\ & = \sum_{r\text { , } i}\left\vert v_{r}^{i_{l}}\right\rangle \left\langle v_{r}^{i_{l}}\right\vert + \sum_{k}\left\vert o_{k}\right\rangle \left\langle o_{k}\right\vert \nonumber\\ & \nonumber\\ & = \mathcal{i}_{2^{n}\times2^{n}}\text{,}\ ] ] since @xmath122 is an orthonormal basis for @xmath33 . for more details , we refer to @xcite . in general , approximate quantum error correction becomes useful when the operator - sum representation of the noise model is defined by errors parametrized by a certain number of small parameters such as the coupling strength between the environment and the quantum system . for the sake of simplicity , suppose the error model is characterized by a single small parameter @xmath123 and assume the goal is to uncover a quantum code for the noise model @xmath48 with fidelity,@xmath124 for some @xmath125 . how strong can be the violation of the standard ( exact ) kl - conditions in order to preserve the desired fidelity order in eq . ( [ preserve ] ) ? in other words , how relaxed can the approximate error correction conditions be so that the inequality in ( [ preserve ] ) is satisfied ? the answer to this important question was provided by leung et _ al_. in @xcite . it turns out that for both exact and approximate quantum error correction conditions , it is necessary that@xmath126 where @xmath127 denotes the total error detection probability . ( [ detection ] ) requires that all the enlarged error operators @xmath128 with maximum detection probability must be included in @xmath129,@xmath130 the important point is that a good overlap between the input and output states is needed while it is not necessary to recover the exact input state @xmath131 , since we do not require @xmath132 . in terms of the enlarged error operators restricted to the codespace , this means that such errors need to be only approximately unitary and mutually orthogonal . these considerations lead to the relaxed sufficient error correction conditions . in analogy to ( [ pd1 ] ) , assume that the polar decomposition for @xmath128 is given by,@xmath133 since @xmath134 restricted to the codespace @xmath28 have different eigenvalues , the exact error correction conditions are not fulfilled . let us say that @xmath135 and @xmath136 are the largest and the smallest eigenvalues , respectively , where both @xmath135 and @xmath137 are @xmath61-numbers . furthermore , let us define the so - called residue operator @xmath138 as @xcite,@xmath139 where,@xmath140 substituting ( [ pi ] ) into ( [ sup ] ) , we get@xmath141 from eq . ( [ qs ] ) and imposing that @xmath142 , the analog of eq . ( [ vai2 ] ) becomes@xmath143 where,@xmath144 we stress that when the exact error correction conditions are satisfied , @xmath145 and @xmath146 ( the null operator ) . thus , in that scenario , eqs . ( [ vai2 ] ) and ( [ vai3 ] ) coincide . finally , we point out that an approximate recovery operation @xmath147 with @xmath148 defined in eq . ( [ recoveryb ] ) * * and @xmath118 formally defined just as in the exact case can be employed in this new scenario as well . however , assuming to consider @xmath98 , extra care in the explicit computation of the unitary operators @xmath149 is needed in view of the fact that the polar decomposition ( [ pd1 ] ) is replaced by the one in ( [ sup ] ) . for an explicit unabridged and correct computation of recovery operators as originally proposed by leung et _ al_. , see appendix a. for further theoretical details , we refer to reference @xcite . the objective in this section is to discuss in detail the exact and approximate error correction conditions for the simplest unital and nonunital channels , respectively . specifically , we consider the bit - flip and the amplitude damping noise models . error correction is performed by means of the three - qubit bit - flip repetition code for the unital channel while we employ the four - qubit leung et _ al_. code for the nonunital noise model . we acknowledge that the bit - flip noise model is certainly not the prototype of a truly quantum noise model . however , we believe its consideration is suitable for our purposes , since we wish to essentially stress the similarities and differences between exact and approximate error correction schemes avoiding unnecessary complications . the exact error correction analysis for more realistic and truly quantum error models along the lines presented here could be found in previous works of one of the authors @xcite . we consider a bit - flip noisy quantum channel and qec is performed via the three - qubit bit - flip repetition code @xcite . we remark that the bit - flip and the phase - flip ( or , dephasing ) channels are unitarily equivalent . this means that there exists a unitary operator * * @xmath150 * * * * such that the action of one channel is the same as the other , provided the first channel is proceed by * * @xmath150 * * * * and followed by * * @xmath151**. * * in the case being considered , it follows that@xmath152 where @xmath153 * * * * denotes the hadamard single - qubit gate . error correction of dephasing errors by means of the three - qubit phase flip repetition code works very much like the error correction of bit - flip errors via the three - qubit bit flip repetition code . that said , we admit that a pure dephasing channel , with no other sources of noise at all , is physically improbable . however , in many physical systems , dephasing is indeed the dominant error source @xcite . the performance of the error correcting code is quantified by means of the entanglement fidelity as function of the error probability . the bit flip noisy channel @xmath154 ( single use of the channel ) is defined as follows,@xmath155 where the matrix representation in the @xmath0-qubit computational basis @xmath156 of the @xmath5-pauli operator is given by,@xmath157 _ { \mathcal{b}_{\text{computational}}}\overset{\text{def}}{=}\left ( \begin{array } [ c]{cc}\left\langle 0|x|0\right\rangle & \left\langle 0|x|1\right\rangle \\ \left\langle 1|x|0\right\rangle & \left\langle 1|x|1\right\rangle \end{array } \right ) = \left ( \begin{array } [ c]{cc}0 & 1\\ 1 & 0 \end{array } \right ) \text{.}\ ] ] observe that the bit - flip channel is a unital channel since @xmath158 . consider the three - qubit bit flip encoding defined as,@xmath159 the action of three uses of the bit flip channel @xmath160 on @xmath161-qubits quantum states reads,@xmath162 where @xmath163 , @xmath164 are pauli operators . furthermore,@xmath165 with,@xmath166 to simplify our notation , we may assume that @xmath167 ... @xmath168 @xmath169 ... @xmath170 . the channel @xmath171 can be written as,@xmath172 where we denote with @xmath173 the superoperator defined in terms of the enlarged error operators @xmath174 . in an explicit way , the error operators @xmath175 read,@xmath176 the set of error operators satisfying the detectability condition , @xmath177 , where @xmath178 @xmath179 is the projector operator on the code subspace @xmath180span@xmath181 is given by,@xmath182 the only non detectable error is @xmath183 . furthermore , since all the detectable errors are invertible , the set of correctable errors is such that @xmath184 is detectable @xcite . it follows that,@xmath185 to be more explicit , the set of enlarged error operators @xmath186 with @xmath187 is correctable provided that,@xmath188 for any pair of @xmath189 with @xmath50 , @xmath190 . ( [ peq ] ) is satisfied if and only if,@xmath191 for any pair of @xmath189 with @xmath50 , @xmath192 @xmath193 . the enlarged error operators @xmath194 in ( [ fuck1 ] ) can be rewritten as,@xmath195 the action of the correctable error operators @xmath196 on the codewords @xmath24 and @xmath197 is given by,@xmath198 the two four - dimensional orthogonal subspaces @xmath199 and @xmath200 of @xmath201 generated by the action of @xmath196 on @xmath24 and @xmath25 are defined as,@xmath202 and,@xmath203 respectively . notice that @xmath204 . the recovery superoperator @xmath205 with @xmath206 , .. , @xmath207 is defined as @xcite,@xmath208 where the unitary operator @xmath209 is such that @xmath210 for @xmath211 . substituting ( [ span1 ] ) and ( [ span2 ] ) into ( [ recovery ] ) , it follows that the four recovery operators @xmath212 are given by,@xmath213 with,@xmath214 we observe that the four recovery operators @xmath215 associated with the four correctable errors @xmath216 with @xmath217 are formally defined as,@xmath218 when considering exact quantum error correction , @xmath219 where the coefficient of proportionality must be determined in such a manner that its product with @xmath220 leads to a unitary operator . this coefficient equals the square root of @xmath221 ( or , @xmath222 ) . we emphasize three features of exact - qec , two of which concern the standard qec recovery superoperator * * @xmath223 * * @xmath224 : * the two eigenvalues @xmath225 and @xmath226 of the @xmath227-matrix associated with the operators @xmath228 ( with @xmath65 correctable errors ) on the codespace @xmath28 coincide . for example , for @xmath229 we have @xmath230 ; * the projector on the codespace @xmath52 belongs to @xmath114 , the standard qec recovery ; * all the four recovery operators in @xmath114 are @xmath231-independent , where @xmath231 denotes the error probability and is the single parameter that characterizes the noise model being considered . for the simple bit - flip noise model with error correction performed by means of the three - qubit bit - flip code , the entanglement fidelity reads @xcite,@xmath232 \right ] } \left ( p\right ) \overset{\text{def}}{=}\frac{1}{\left ( \dim_{\mathbb{c } } \mathcal{c}\right ) ^{2}}\sum_{l=0}^{7}{\displaystyle\sum\limits_{k=0}^{3 } } \left\vert \text{tr}\left ( r_{k}a_{l}^{\prime}\right ) _ { \mathcal{c}}\right\vert ^{2}=\frac{1}{4}\sum_{l=0}^{7}{\displaystyle\sum\limits_{k=0}^{3 } } \left\vert \left\langle 0_{l}\left\vert r_{k}a_{l}^{\prime}\right\vert 0_{l}\right\rangle + \left\langle 1_{l}\left\vert r_{k}a_{l}^{\prime } \right\vert 1_{l}\right\rangle \right\vert ^{2}\text{. } \label{ef}\ ] ] substituting ( [ rj ] ) into the rhs of ( [ ef ] ) , we obtain@xmath232 \right ] } \left ( p\right ) = \frac{1}{4}\sum_{l=0}^{7}{\displaystyle\sum\limits_{k=0}^{3 } } \left\vert \frac{\left\langle 0_{l}\left\vert a_{k}^{\prime\dagger}a_{l}^{\prime}\right\vert 0_{l}\right\rangle } { \sqrt{\left\langle 0_{l}\left\vert a_{k}^{\prime\dagger}a_{k}^{\prime}\right\vert 0_{l}\right\rangle } } + \frac{\left\langle 1_{l}\left\vert a_{k}^{\prime\dagger}a_{l}^{\prime}\right\vert 1_{l}\right\rangle } { \sqrt{\left\langle 1_{l}\left\vert a_{k}^{\prime\dagger}a_{k}^{\prime}\right\vert 1_{l}\right\rangle } } \right\vert ^{2}\text{.}\ ] ] we observe that @xmath233 \right ] } \left ( p\right ) $ ] is , in principle , the sum of @xmath234-terms that arise by considering all the possible pairs @xmath235 with @xmath236 and @xmath237 . however , it turns out that only @xmath207-terms are nonvanishing and contribute to the computation of the entanglement fidelity . they are @xmath238 . thus , only the four correctable errors @xmath239 are recoverable . indeed , they are fully recovered and,@xmath240 in the exact - qec scenario , we stress : * only the correctable errors are recoverable . indeed , they are fully recoverable . no off - diagonal contribution arises . in summary , @xmath233 \right ] } \left ( p\right ) $ ] reads@xmath241 \right ] } \left ( p\right ) & = \frac{1}{4}\left [ \begin{array } [ c]{c}\left\vert \frac{\left\langle 0_{l}\left\vert a_{0}^{\prime\dagger}a_{0}^{\prime}\right\vert 0_{l}\right\rangle } { \sqrt{\left\langle 0_{l}\left\vert a_{0}^{\prime\dagger}a_{0}^{\prime}\right\vert 0_{l}\right\rangle } } + \frac{\left\langle 1_{l}\left\vert a_{0}^{\prime\dagger}a_{0}^{\prime}\right\vert 1_{l}\right\rangle } { \sqrt{\left\langle 1_{l}\left\vert a_{0}^{\prime\dagger}a_{0}^{\prime}\right\vert 1_{l}\right\rangle } } \right\vert ^{2}+\left\vert \frac{\left\langle 0_{l}\left\vert a_{1}^{\prime\dagger}a_{1}^{\prime}\right\vert 0_{l}\right\rangle } { \sqrt{\left\langle 0_{l}\left\vert a_{1}^{\prime\dagger}a_{1}^{\prime } \right\vert 0_{l}\right\rangle } } + \frac{\left\langle 1_{l}\left\vert a_{1}^{\prime\dagger}a_{1}^{\prime}\right\vert 1_{l}\right\rangle } { \sqrt{\left\langle 1_{l}\left\vert a_{1}^{\prime\dagger}a_{1}^{\prime } \right\vert 1_{l}\right\rangle } } \right\vert ^{2}+\\ \\ \left\vert \frac{\left\langle 0_{l}\left\vert a_{2}^{\prime\dagger}a_{2}^{\prime}\right\vert 0_{l}\right\rangle } { \sqrt{\left\langle 0_{l}\left\vert a_{2}^{\prime\dagger}a_{2}^{\prime}\right\vert 0_{l}\right\rangle } } + \frac{\left\langle 1_{l}\left\vert a_{2}^{\prime\dagger}a_{2}^{\prime}\right\vert 1_{l}\right\rangle } { \sqrt{\left\langle 1_{l}\left\vert a_{2}^{\prime\dagger}a_{2}^{\prime}\right\vert 1_{l}\right\rangle } } \right\vert ^{2}+\left\vert \frac{\left\langle 0_{l}\left\vert a_{3}^{\prime\dagger}a_{3}^{\prime}\right\vert 0_{l}\right\rangle } { \sqrt{\left\langle 0_{l}\left\vert a_{3}^{\prime\dagger}a_{3}^{\prime } \right\vert 0_{l}\right\rangle } } + \frac{\left\langle 1_{l}\left\vert a_{4}^{\prime\dagger}a_{4}^{\prime}\right\vert 1_{l}\right\rangle } { \sqrt{\left\langle 1_{l}\left\vert a_{4}^{\prime\dagger}a_{4}^{\prime } \right\vert 1_{l}\right\rangle } } \right\vert ^{2}\end{array } \right ] \nonumber\\ & \nonumber\\ & = \frac{1}{4}\left [ 4\left\langle 0_{l}\left\vert a_{0}^{\prime\dagger } a_{0}^{\prime}\right\vert 0_{l}\right\rangle + 4\left\langle 0_{l}\left\vert a_{1}^{\prime\dagger}a_{1}^{\prime}\right\vert 0_{l}\right\rangle + 4\left\langle 0_{l}\left\vert a_{2}^{\prime\dagger}a_{2}^{\prime}\right\vert 0_{l}\right\rangle + 4\left\langle 0_{l}\left\vert a_{3}^{\prime\dagger}a_{3}^{\prime}\right\vert 0_{l}\right\rangle \right ] \text{,}\ ] ] that is,@xmath232 \right ] } \left ( p\right ) = \left\langle 0_{l}\left\vert a_{0}^{\prime\dagger}a_{0}^{\prime}\right\vert 0_{l}\right\rangle + \left\langle 0_{l}\left\vert a_{1}^{\prime\dagger}a_{1}^{\prime}\right\vert 0_{l}\right\rangle + \left\langle 0_{l}\left\vert a_{2}^{\prime\dagger}a_{2}^{\prime}\right\vert 0_{l}\right\rangle + \left\langle 0_{l}\left\vert a_{3}^{\prime\dagger}a_{3}^{\prime}\right\vert 0_{l}\right\rangle \text{. } \label{chist}\ ] ] substituting ( [ enlarged ] ) into ( [ chist ] ) , we get@xmath232 \right ] } \left ( p\right ) = 1 - 3p^{2}+2p^{3}\text{.}\ ] ] when the error probability @xmath231 increases beyond a certain threshold @xmath242 , quantum error correction does more harm than good . to uncover this point @xmath242 , we have to check two conditions . first , we compare @xmath233 \right ] } \left ( p\right ) $ ] with the fidelity without coding and error correction ( the so - called single - qubit baseline performance),@xmath243 for this error correction scheme to be useful , it must be@xmath244 \right ] } \left ( p\right ) \text{.}\ ] ] in the case being considered , this inequality holds true for any @xmath245 . second , the error correction scheme is effective provided that the failure probability @xmath246 \right ] } \left ( p\right ) $ ] is smaller than the error probability @xmath231,@xmath247 this second inequality holds true if and only if @xmath248 . an approximate qec framework turns out to be of great use when combatting non - pauli errors . within such framework , we allow for a negligible but non - vanishing error in the recovery so that errors need not be exactly orthogonal to be unambiguously detected and perfectly recovered . indeed , we allow for slight non - orthogonalities between approximately correctable error operators . this way , correctable errors have to satisfy the kl - conditions only approximately . as a consequence , in such a scenario , the composite operation @xmath249 is necessarily only approximately close to the identity on the codespace . observe that in such approximate qec framework , for a given noise model , more codes satisfying the approximate kl - conditions can be constructed . furthermore , it is not unusual to uncover codes of shorter block lengths which , although of less general applicability , may indeed be more efficient for the specific error model considered . for instance , when considering amplitude damping errors in the standard @xmath250 , @xmath15 non - pauli error basis on a @xmath32-qubits state , to the first order in @xmath14 , @xmath251-errors may occur . thus , in order to be correctable by this nondegenerate non - pauli basis code , such errors must map the codeword space to orthogonal spaces if the syndrome is to be detected unambiguously . thus , it must be @xmath252 , that is @xmath253 . instead , considering the error correction of the same decoherence model by means of nondegenerate standard pauli basis codes , it must be @xmath254 , that is @xmath255 . the former scenario arises when considering the amplitude damping channel and using the leung et _ @xmath256 \right ] $ ] code . in the case of amplitude damping , we model the environment as starting in the @xmath257 state as it were at zero temperature . the ad quantum noisy channel is defined as @xcite,@xmath258 where the kraus error operators @xmath38 read , @xmath259 \text { , } a_{1}\overset{\text{def}}{=}\frac{\sqrt{\gamma}}{2}\left ( \sigma_{x}+i\sigma_{y}\right ) \text{.}\ ] ] observe that the ad channel is nonunital since @xmath260 . the @xmath227-matrix representation of the @xmath38 operators is given by,@xmath261{cc}1 & 0\\ 0 & \sqrt{1-\gamma}\end{array } \right ) \text { and , } a_{1}=\left ( \begin{array } [ c]{cc}0 & \sqrt{\gamma}\\ 0 & 0 \end{array } \right ) \text{.}\ ] ] the action of the @xmath38 with @xmath262 operators on the computational basis vectors @xmath257 and @xmath263 reads,@xmath264 and,@xmath265 respectively . the codewords of the leung et _ @xmath266 \right ] $ ] quantum code are given by @xcite,@xmath267 we underline that this code is a two - dimensional subspace of the @xmath268-dimensional _ complex _ hilbert space @xmath27 and is spanned by self - complementary codewords . recall that a code @xmath28 is called self - complementary if its codespace is spanned by codewords @xmath269 defined as,@xmath270 where @xmath271 is a binary string of length @xmath32 and @xmath272 is the complement of @xmath271 . in appendix b , we show that , in addition to the leung et _ al_. four - qubit code , there are only two additional two - dimensional subspaces spanned by self - complementary codewords in @xmath27 capable of error - correcting single ad - errors . after the encoding operation , the total set of enlarged error operators is given by the following @xmath268 enlarged error operators , @xmath273{c}a_{0000}\text { , } a_{1000}\text { , } a_{0100}\text { , } a_{0010}\text { , } a_{0001}\text { , } a_{1100}\text { , } a_{1010}\text { , } a_{1001}\text { , } a_{0110}\text { , } a_{0101}\text { , } a_{0011}\text{,}\\ \\ a_{1110}\text { , } a_{1011}\text { , } a_{0111}\text { , } a_{1101}\text { , } a_{1111}\end{array } \right\ } \text{,}\ ] ] where,@xmath274 consider the following quantum state @xmath275,@xmath276 where @xmath277 , @xmath278 and @xmath279 . then , the action of the weight-@xmath280 enlarged error operator @xmath281 on @xmath275 reads,@xmath282 + \beta\left [ \left ( 1-\gamma\right ) \frac{\left ( \left\vert 0011\right\rangle + \left\vert 1100\right\rangle \right ) } { \sqrt { 2}}\right ] \text{.}\ ] ] the action of the four weight-@xmath0 enlarged error operators is given by,@xmath283 \text { , } a_{0100}\left\vert \psi\right\rangle = \sqrt{\frac{\gamma\left ( 1-\gamma\right ) } { 2}}\left [ \alpha\left ( 1-\gamma\right ) \left\vert 1011\right\rangle + \beta\left\vert 1000\right\rangle \right ] \text{,}\nonumber\\ a_{0010}\left\vert \psi\right\rangle & = \sqrt{\frac{\gamma\left ( 1-\gamma\right ) } { 2}}\left [ \alpha\left ( 1-\gamma\right ) \left\vert 1101\right\rangle + \beta\left\vert 0001\right\rangle \right ] \text { , } a_{0001}\left\vert \psi\right\rangle = \sqrt{\frac{\gamma\left ( 1-\gamma\right ) } { 2}}\left [ \alpha\left ( 1-\gamma\right ) \left\vert 1110\right\rangle + \beta\left\vert 0010\right\rangle \right ] \text{.}\ ] ] the action of the six weight-@xmath284 enlarged error operators reads,@xmath285 \text { , } a_{1010}\left\vert \psi\right\rangle = \frac{\alpha}{\sqrt{2}}\gamma\left ( 1-\gamma\right ) \left\vert 0101\right\rangle \text { , } \nonumber\\ a_{1001}\left\vert \psi\right\rangle & = \frac{\alpha}{\sqrt{2}}\gamma\left ( 1-\gamma\right ) \left\vert 0110\right\rangle \text { , } a_{0110}\left\vert \psi\right\rangle = \frac{\alpha}{\sqrt{2}}\gamma\left ( 1-\gamma\right ) \left\vert 1001\right\rangle \text { , } \nonumber\\ a_{0101}\left\vert \psi\right\rangle & = \frac{\alpha}{\sqrt{2}}\gamma\left ( 1-\gamma\right ) \left\vert 1010\right\rangle \text { , } a_{0011}\left\vert \psi\right\rangle = \frac{\gamma}{\sqrt{2}}\left [ \alpha\left ( 1-\gamma \right ) \left\vert 1100\right\rangle + \beta\left\vert 0000\right\rangle \right ] \text{.}\ ] ] the action of the four weight-@xmath161 enlarged error operators is given by,@xmath286 finally , the action of the weight-@xmath207 enlarged error operator reads,@xmath287 for the sake of completeness , observe that@xmath288 where @xmath289 denotes the probability that @xmath290 occurs . we recall that _ _ _ _ for a given code @xmath28 , the set of detectable errors is closed under linear combinations . that is , if @xmath291 and @xmath292 are both detectable , then so is @xmath293 . this useful property implies that to check detectability , one has to consider only the elements of a linear basis for the space of errors of interest . an enlarged error operator @xmath38 is detectable if and only if,@xmath294 where @xmath295 is the projector on the codespace @xmath28 . condition ( [ con ] ) requires that for detectable errors it must be,@xmath296 for the weight-@xmath280 enlarged error operator @xmath281 , we have@xmath297 therefore , @xmath281 is detectable . similarly , it turns out that the four weight-@xmath0 enlarged error operators @xmath298 , @xmath299 , @xmath300 and @xmath301 are detectable . for instance , for @xmath299 we obtain@xmath302 considering the weight-@xmath284 enlarged error operators , it follows that @xmath303 and @xmath304 are not detectable since@xmath305 and,@xmath306 on the contrary the weight-@xmath284 enlarged error operators @xmath307 , @xmath308 , @xmath309 and @xmath310 are detectable . for instance , for @xmath307 we have@xmath311 the four weight-@xmath161 enlarged error operators @xmath312 , @xmath313 , @xmath314 and @xmath315 are all detectable . for each one of them we get the same type of relations which hold true for @xmath312 . for instance,@xmath316 finally , the weight-@xmath207 enlarged error operator @xmath317 is not detectable since@xmath318 we point out that the physical reason why @xmath281 is detectable and @xmath317 is not detectable is as follows : there is a nonzero probability for the error @xmath281 to occur within the considered orders ( up to linear orders in gamma ) , whereas the error @xmath317 would simply never occur in those allowed orders ( @xmath280-th and @xmath0-st in gamma ) ; in other words , by ignoring terms proportional to @xmath319 , the @xmath317 error ( four photons get lost ) simply does not exist and thus it can not be referred to as detectable . in conclusion , we have@xmath320 we also recall that the notion of correctability depends on all the errors in the set under consideration and , unlike detectability , can not be applied to individual errors @xcite . furthermore , it is important to note that a linear combination of correctable errors is also a correctable error . a set of enlarged error operators @xmath321 is correctable iff,@xmath322 condition ( [ con2 ] ) requires that for correctable errors it must be,@xmath323 in the case under investigation , it turns out that the following set of enlarged error operators is correctable@xmath324 when @xmath325 , error operators in @xmath196 perfectly ( arbitrary order in @xmath14 ) satisfy the conditions in ( [ kl ] ) . when @xmath326 , we have@xmath327 therefore , the kl - conditions in ( [ kl ] ) are only approximately fulfilled to the first order in the damping parameter @xmath14 . let us construct now the standard qec recovery operators . following our remarks in section ii , we observe that the suitable orthonormal basis @xmath328 for the @xmath268-dimensional _ complex _ hilbert space @xmath27 reads,@xmath329 with,@xmath330 and,@xmath331 the standard qec recovery superoperator @xmath114 is given by,@xmath332 where,@xmath333 we remark that , unlike the exact case , we have now : * the two eigenvalues @xmath225 and @xmath226 of the @xmath227-matrix associated with the operators @xmath334 ( with @xmath38 correctable errors ) on the codespace @xmath28 do not coincide . for example , for @xmath335 we have @xmath336 and @xmath337 . the discrepancy between the two eigenvalues is a fingerprint of the non - unitarity of @xmath338 where @xmath38 is correctable ; * the non - tracelessness of the operators @xmath339 with @xmath325 is an indicator of the non - orthogonality between @xmath340 and @xmath341 ; * the projector on the codespace @xmath52 does not belong to @xmath114 , the standard qec recovery ; * there exist recovery operators in @xmath114 that are @xmath342-dependent , where @xmath14 denotes the damping probability and is the single parameter that characterizes the noise model being considered . in this case , it turns out that the entanglement fidelity becomes,@xmath343 \right ] } ^{\text{qec - recovery}}\left ( \gamma\right ) \overset{\text{def}}{=}\frac{1}{\left ( 2\right ) ^{2}}\sum_{l\text { , } k}\left\vert \text{tr}\left ( r_{k}a_{l}\right ) _ { \mathcal{c}}\right\vert ^{2}\nonumber\\ & \nonumber\\ & = \frac{1}{4}\left ( \sqrt{\frac{1+\left ( 1-\gamma\right ) ^{4}}{2}}+\sqrt{\frac{2\left ( 1-\gamma\right ) ^{2}}{2}}\right ) ^{2}+\left ( \sqrt{\frac{\gamma\left ( 1-\gamma\right ) ^{3}}{2}}+\sqrt{\frac{\gamma\left ( 1-\gamma\right ) } { 2}}\right ) ^{2}+\left ( \frac{1}{4}\frac{2}{1+\left ( 1-\gamma\right ) ^{4}}\left ( \frac{\gamma^{2}}{2}\right ) ^{2}\right ) + \nonumber\\ & \nonumber\\ & + \left ( \frac{1}{4}\left ( \frac{\gamma^{2}\left ( 1-\gamma\right ) ^{2}\left ( \left ( 1-\gamma\right ) ^{2}-1\right ) } { 2\left ( 1+\left ( 1-\gamma\right ) ^{4}\right ) } \right ) ^{2}\right ) \nonumber\\ & \nonumber\\ & \approx1 - 2\gamma^{2}+o\left ( \gamma^{3}\right ) \text{,}\ ] ] that is,@xmath344 \right ] } ^{\text{qec - recovery}}\left ( \gamma\right ) \approx1 - 2\gamma^{2}+o\left ( \gamma^{3}\right ) \text{. } \label{qec - recovery}\ ] ] we stress that @xmath345 \right ] } ^{\text{qec - recovery}}\left ( \gamma\right ) $ ] is , in principle , the sum of @xmath346-terms that arise by considering all the possible pairs @xmath347 with @xmath348 and @xmath349 . however , it turns out that only @xmath350-terms are nonvanishing and contribute to the computation of the entanglement fidelity . they are @xmath351 . thus , not only the five correctable errors @xmath352 are partially recoverable since@xmath353 but there is also the emergence of an off - diagonal contribution @xmath354 . thus , unlike the exact scenario , we have for the approximate case that : * not only the correctable errors are recoverable . indeed , they are not fully recoverable . off - diagonal contributions do arise . as we have noticed in eq . ( [ 99 ] ) , the standard qec recovery does not contain the projector on the codespace as possible recovery operator . in this new case , the chosen ( orthonormal ) basis vectors spanning @xmath27 are given by,@xmath355 the code - projected recovery ( cp recovery ) becomes,@xmath356 where,@xmath357 observe that,@xmath358 the entanglement fidelity becomes,@xmath344 \right ] } ^{\text{cp - recovery}}\left ( \gamma\right ) \overset{\text{def}}{=}\frac{1}{\left ( 2\right ) ^{2}}\sum_{k=0}^{15}\sum_{l=1}^{10}\left\vert \text{tr}\left ( r_{l}a_{k}^{\prime}\right ) _ { \left\vert \mathcal{c}\right . } \right\vert ^{2}\text { , } \label{108}\ ] ] where @xmath359 and @xmath360 , @xmath361 , ... , we point out that both the recovery operators @xmath363 and @xmath364 contribute to the entanglement fidelity in eq . ( [ 108 ] ) since,@xmath365 and,@xmath366 furthermore , the contributions of recovery operators @xmath367 , @xmath368 , @xmath369 , @xmath370 are given by,@xmath371 and,@xmath372 respectively . finally , the contribution arising from the recovery operators @xmath373 , @xmath374 , @xmath375 , @xmath376 becomes transparent once we consider the following relations , @xmath377 we notice that the six enlarged error operators @xmath303 , @xmath304 , @xmath312 , @xmath313 , @xmath314 , @xmath315 do not contribute to the computation of the entanglement fidelity @xmath378 \right ] } ^{\text{cp - recovery}}\left ( \gamma\right ) $ ] . finally , we obtain@xmath379 \right ] } ^{\text{cp - recovery}}\left ( \gamma\right ) & = \frac{1}{4}\left\ { \begin{array } [ c]{c}\left [ \left ( 1-\gamma+\frac{\gamma^{2}}{2}\right ) + \left ( 1-\gamma \right ) \right ] ^{2}+\left ( \gamma-\frac{\gamma^{2}}{2}\right ) ^{2}+2\left ( \frac{\gamma^{2}}{2}\right ) ^{2}+4\left [ \left ( 2-\gamma\right ) \sqrt{\frac{\gamma\left ( 1-\gamma\right ) } { 2}}\right ] ^{2}+\\ \\ + 4\left [ \frac{\gamma\left ( 1-\gamma\right ) } { \sqrt{2}}\right ] ^{2}\end{array } \right\ } \text{,}\nonumber\\ & \nonumber\\ & \approx1-\frac{7}{4}\gamma^{2}+\mathcal{o}\left ( \gamma^{3}\right ) \text{,}\ ] ] that is,@xmath344 \right ] } ^{\text{cp - recovery}}\left ( \gamma\right ) \approx1-\frac{7}{4}\gamma^{2}+\mathcal{o}\left ( \gamma^{3}\right ) \text{. } \label{cp - recovery}\ ] ] from eqs . ( [ qec - recovery ] ) and ( [ cp - recovery ] ) , it turns out that as far as the entanglement fidelity concerns , the cp recovery scheme is more successful than the standard qec recovery scheme . in addition to the standard qec and cp recovery schemes , it is possible to consider additional recovery schemes such as an analytically - optimized version of a channel - adapted recovery scheme as proposed by fletcher et _ al_. in @xcite . consider the cp recovery scheme in eq . ( [ fff ] ) where , however , the recovery operators @xmath363 and @xmath364 are defined as @xcite , @xmath380 and,@xmath381 respectively , where @xmath271 , @xmath382 with @xmath383 . the remaining eight recovery operators are defined just as in eq . ( [ fff ] ) . the set of all ten recovery operators forms the fletcher et _ al_. recovery operation @xmath384 . note that,@xmath385 and,@xmath386 using ( [ i ] ) and ( [ ii ] ) , we get@xmath387 it turns out that for the fletcher et _ al_. recovery ( f - recovery ) operations,@xmath388 in this case , the entanglement fidelity @xmath378 \right ] } ^{\text{f - recovery}}$ ] reads,@xmath344 \right ] } ^{\text{f - recovery}}\overset{\text{def}}{=}\frac{1}{\left ( 2\right ) ^{2}}\sum_{k=0}^{15}\sum_{l=1}^{10}\left\vert \text{tr}\left ( r_{l}a_{k}^{\prime}\right ) _ { \left\vert \mathcal{c}\right . } \right\vert ^{2}\text{,}\ ] ] where @xmath389 and @xmath360 , @xmath361 , ... , @xmath362 . notice that,@xmath390 while the remaining terms are the same as obtained in the previous analysis performed with the traditional qec recovery scheme . following the line of reasoning provide in the former computations , we get @xmath391 \right ] } ^{\text{f - recovery}}\left ( \gamma\right ) \equiv\mathcal{f}_{\left [ \left [ 4,1\right ] \right ] } \left ( a\text { , } b\text { , } \gamma\right ) $ ] with,@xmath344 \right ] } \left ( a\text { , } b\text { , } \gamma\right ) = \frac{1}{4}\left\ { \left\vert \frac{a+b\left ( 1-\gamma\right ) ^{2}}{\sqrt{2}}+\left ( 1-\gamma\right ) \right\vert ^{2}+\left\vert \frac{b^{\ast}-a^{\ast}\left ( 1-\gamma\right ) ^{2}}{\sqrt { 2}}\right\vert ^{2}+2\gamma\left ( 1-\gamma\right ) \left ( 2-\gamma\right ) ^{2}+2\gamma^{2}\left ( 1-\gamma\right ) ^{2}+\frac{\gamma^{4}}{2}\right\ } \text{.}\ ] ] we wish to maximize @xmath345 \right ] } \left ( a\text { , } b\text { , } \gamma\right ) $ ] . the problem is to find @xmath392 and @xmath393 ( perhaps @xmath14-dependent quantities ) such that @xmath345 \right ] } \left ( \bar{a}\text { , } \bar{b}\text { , } \gamma\right ) $ ] denotes the searched maximum,@xmath344 \right ] } \left ( \bar{a}\text { , } \bar{b}\text { , } \gamma\right ) = \underset{\left\vert a\right\vert ^{2}+\left\vert b\right\vert ^{2}=1}{\max}\mathcal{f}\left ( a\text { , } b\text { , } \gamma\right ) \text{.}\ ] ] it can be shown that ( for details , see appendix c),@xmath344 \right ] } \left ( \bar{a}\text { , } \bar{b}\text { , } \gamma\right ) = 1-\frac{3}{2}\gamma^{2}+\mathcal{o}\left ( \gamma^{3}\right ) \text{,}\ ] ] with@xmath394 finally , @xmath344 \right ] } ^{\text{f - recovery}}\left ( \gamma\right ) \approx1-\frac{3}{2}\gamma^{2}+\mathcal{o}\left ( \gamma ^{3}\right ) \text{. } \label{f - recovery}\ ] ] from eqs . ( [ qec - recovery ] ) , ( [ cp - recovery ] ) and ( [ f - recovery ] ) , it turns out that as far as the entanglement fidelity concerns , the analytically - optimized f - recovery scheme is better than both the standard qec and cp recovery schemes . the comparison of the three recovery schemes employed can be visualized in fig . @xmath0 . vs. the amplitude damping parameter @xmath14 with @xmath395 for the leung et _ al . _ four - qubit code for amplitude damping errors ; the fletcher - type recovery ( dashed line ) , the code - projected recovery ( thin solid line ) and , the standard qec - recovery ( thick solid line).,scaledwidth=50.0% ] in this article , we presented a comparative analysis of exact and approximate quantum error correction by means of simple unabridged analytical computations . for the sake of clarity , using primitive quantum codes , we showed a detailed study of exact and approximate error correction for the two simplest unital ( pauli errors ) and nonunital ( non - pauli errors ) noise models , respectively . the similarities and differences between the two scenarios were stressed . in addition , the performances of quantum codes quantified by means of the entanglement fidelity for different recovery schemes were taken into consideration in the approximate case . our main findings , some of which appear in the appendices to ease the readability of the article , can be outlined as follows : 1 . we have explicitly constructed one of the recovery operators as originally proposed by leung et _ al_. in @xcite . as a by - product , we also found the correct version of eq . @xmath396 in @xcite . our version is represented by eq . ( [ correct ] ) in appendix a. 2 . we have explicitly discussed the similarities and differences between exact and approximate - qec schemes for very simple noise models and very common stabilizer codes . our analysis is purely analytical and no numerical consideration is required . thus , it is straightforward to follow and , we believe , has considerable pedagogical and explanatory relevance . in particular , the points to be stressed in the _ exact case _ are : * the two eigenvalues @xmath225 and @xmath226 of the @xmath227-matrix associated with the operators @xmath334 ( with @xmath38 correctable errors ) on the codespace @xmath28 coincide ; * the projector on the codespace @xmath52 belongs to the standard qec recovery @xmath114 ; * all the recovery operators in @xmath114 are @xmath231-independent ; * the correctable errors are fully recoverable . no off - diagonal contribution arises . on the other side , the main points to be stressed in the _ approximate case _ are : * the two eigenvalues @xmath225 and @xmath226 of the @xmath227-matrix associated with the operators @xmath334 ( with @xmath38 correctable errors ) on the codespace @xmath28 do not coincide ; * the discrepancy between the two eigenvalues is a fingerprint of the non - unitarity of @xmath338 where @xmath38 is a correctable error ; * the non - tracelessness of the operators @xmath339 with @xmath325 is an indicator of the non - orthogonality between @xmath340 and @xmath341 ; * the projector on the codespace @xmath52 does not belong to the standard qec recovery @xmath114 ; * there exist recovery operators in @xmath114 that are @xmath14-dependent ; * the correctable errors are not fully recoverable . off - diagonal contributions do arise . 1 . we have explicitly shown that there are only three possible self - complementary quantum codes characterized by a two - dimensional subspace of the sixteen - dimensional _ complex _ hilbert space @xmath27 capable of error - correcting single - ad errors . thus , in this regard , the leung et _ al_. four - qubit code is not unique . our three codes appear in eqs . ( [ a ] ) , ( [ b ] ) and ( [ c ] ) in appendix b. 2 . in the approximate - qec case , we have explicitly computed the entanglement fidelity for three different recovery schemes . in particular , eq . ( [ qec - recovery ] ) for the standard qec recovery has , to the best of our knowledge , never appeared in the literature ( neither numerically nor analytically ) ; furthermore , eq . ( [ cp - recovery ] ) for the code - projected recovery is the analytical counterpart of the numerical finding presented in @xcite ; finally , eq . ( [ f - recovery ] ) represents our analytical contribution to the understanding of the numerical result presented in @xcite . although our investigation is limited to very simple noise models and very simple codes , we hope that it will inspire other researchers to pursue novel analytical studies of more realistic noise models and higher - dimensional quantum codes . after all , for such type of investigations , analytical computations can become considerably messy ( as pointed out in @xcite ) and understanding in an analytical fashion recovery maps numerically computed can become quite a tricky task as well ( as stressed in @xcite ) . in conclusion , also in view of these very last considerations , we are very confident about the relevance of the pedagogical nature of our analytical investigation carried out in this article . we thank the era - net chist - era project hipercom for financial support . for the sake of clarity , we limit our analysis to the explicit computation of the leung et _ al_. recovery operator for the enlarged error operator @xmath281 . in principle , the remaining recovery operators can be computed in the same manner . observe that in general we should be dealing with operators acting on the @xmath268-dimensional _ complex _ hilbert space @xmath27 . however , in what follows , we shall take into consideration only lower - dimensional matrix - representations of operators where the dimension is limited to nontrivial contributions . for instance , for @xmath281 and @xmath52 , we consider their matrix - representation restricted to the four - dimensional subspace of @xmath27 spanned by the orthonormal vectors,@xmath397 we obtain,@xmath398{cccc}1 & 0 & 0 & 1\\ 0 & 1 & 1 & 0\\ 0 & 1 & 1 & 0\\ 1 & 0 & 0 & 1 \end{array } \right ) \text { and , } a_{0000}\overset{\text{def}}{=}\left ( \begin{array } [ c]{cccc}1 & 0 & 0 & 0\\ 0 & 1-\gamma & 0 & 0\\ 0 & 0 & 1-\gamma & 0\\ 0 & 0 & 0 & \left ( 1-\gamma\right ) ^{2}\end{array } \right ) \text{. } \label{pa}\ ] ] from eq . ( [ pa ] ) , it follows that the two eigenvalues of @xmath399 are given by,@xmath400 while @xmath401 reads,@xmath402{cccc}\frac{\left ( 1-\gamma\right ) ^{4}+1}{4 } & 0 & 0 & \frac{\left ( 1-\gamma\right ) ^{4}+1}{4}\\ 0 & \frac{\left ( 1-\gamma\right ) ^{2}}{2 } & \frac{\left ( 1-\gamma\right ) ^{2}}{2 } & 0\\ 0 & \frac{\left ( 1-\gamma\right ) ^{2}}{2 } & \frac{\left ( 1-\gamma\right ) ^{2}}{2 } & 0\\ \frac{\left ( 1-\gamma\right ) ^{4}+1}{4 } & 0 & 0 & \frac{\left ( 1-\gamma\right ) ^{4}+1}{4}\end{array } \right ) ^{\frac{1}{2}}\text{.}\ ] ] after some algebra , we have@xmath403 where,@xmath404 and,@xmath405{c}0\\ 1\\ 1\\ 0 \end{array } \right ) \text { , } \left\vert v_{2}\right\rangle \overset{\text{def}}{=}\frac{1}{\sqrt{2}}\left ( \begin{array } [ c]{c}0\\ -1\\ 1\\ 0 \end{array } \right ) \text { , } \left\vert v_{3}\right\rangle \overset{\text{def}}{=}\frac{1}{\sqrt{2}}\left ( \begin{array } [ c]{c}-1\\ 0\\ 0\\ 1 \end{array } \right ) \text { , } \left\vert v_{4}\right\rangle \overset{\text{def}}{=}\frac{1}{\sqrt{2}}\left ( \begin{array } [ c]{c}1\\ 0\\ 0\\ 1 \end{array } \right ) \text{. } \label{cafe1}\ ] ] substituting ( [ cafe1 ] ) and ( [ cafe2 ] ) into ( [ cafe3 ] ) , we get@xmath406{cccc}\sqrt{\frac{\left ( 1-\gamma\right ) ^{4}+1}{2 } } & 0 & 0 & \sqrt{\frac{\left ( 1-\gamma\right ) ^{4}+1}{2}}\\ 0 & 1-\gamma & 1-\gamma & 0\\ 0 & 1-\gamma & 1-\gamma & 0\\ \sqrt{\frac{\left ( 1-\gamma\right ) ^{4}+1}{2 } } & 0 & 0 & \sqrt{\frac{\left ( 1-\gamma\right ) ^{4}+1}{2}}\end{array } \right ) \text{.}\ ] ] recall that the residue operator @xmath407 is given by,@xmath408 that is,@xmath409{cccc}\frac{1}{2}\gamma+\frac{1}{2}\sqrt{\frac{1}{2}\left ( \gamma-1\right ) ^{4}+\frac{1}{2}}-\frac{1}{2 } & 0 & 0 & \frac{1}{2}\gamma+\frac{1}{2}\sqrt{\frac{1}{2}\left ( \gamma-1\right ) ^{4}+\frac{1}{2}}-\frac{1}{2}\\ 0 & 0 & 0 & 0\\ 0 & 0 & 0 & 0\\ \frac{1}{2}\gamma+\frac{1}{2}\sqrt{\frac{1}{2}\left ( \gamma-1\right ) ^{4}+\frac{1}{2}}-\frac{1}{2 } & 0 & 0 & \frac{1}{2}\gamma+\frac{1}{2}\sqrt{\frac{1}{2}\left ( \gamma-1\right ) ^{4}+\frac{1}{2}}-\frac{1}{2}\end{array } \right ) \text{. } \label{correct}\ ] ] observe that for @xmath410 , @xmath407 becomes@xmath411{cccc}1 & 0 & 0 & 1\\ 0 & 0 & 0 & 0\\ 0 & 0 & 0 & 0\\ 1 & 0 & 0 & 1 \end{array } \right ) + \mathcal{o}\left ( \gamma^{4}\right ) \text{.}\ ] ] let us focus now on the computation of the unitary operator @xmath412 . from eqs . ( [ pa ] ) and ( [ cafe1 ] ) , we get@xmath413{c}0\\ 1\\ 1\\ 0 \end{array } \right ) \text { , } a_{0000}p_{\mathcal{c}}\left\vert v_{2}\right\rangle \overset{\text{def}}{=}\left ( \begin{array } [ c]{c}0\\ 0\\ 0\\ 0 \end{array } \right ) \text { , } a_{0000}p_{\mathcal{c}}\left\vert v_{3}\right\rangle \overset{\text{def}}{=}\left ( \begin{array } [ c]{c}0\\ 0\\ 0\\ 0 \end{array } \right ) \text { , } \nonumber\\ & \nonumber\\ & a_{0000}p_{\mathcal{c}}\left\vert v_{4}\right\rangle \overset{\text{def}}{=}\text { } \frac{1}{\sqrt{2}}\left ( \begin{array } [ c]{c}1\\ 0\\ 0\\ \left ( 1-\gamma\right ) ^{2}\end{array } \right ) \text{.}\ ] ] consider the following basis given by,@xmath414 with,@xmath415{c}0\\ 1\\ 1\\ 0 \end{array } \right ) \text { , } \left\vert e_{2}\right\rangle \overset{\text{def}}{=}\frac{1}{\sqrt{2}}\left ( \begin{array } [ c]{c}0\\ -1\\ 1\\ 0 \end{array } \right ) \text { , } \left\vert e_{3}\right\rangle \overset{\text{def}}{=}\frac{1}{\sqrt{2}}\left ( \begin{array } [ c]{c}-1\\ 0\\ 0\\ 1 \end{array } \right ) \text { , } \nonumber\\ & \nonumber\\ \left\vert e_{4}\right\rangle \overset{\text{def}}{=}\frac{a_{0000}p_{\mathcal{c}}\left\vert v_{4}\right\rangle } { \lambda_{4 } } & = \frac { 1}{\sqrt{2}}\frac{1}{\sqrt{\frac{1+\left ( 1-\gamma\right ) ^{4}}{2}}}\left ( \begin{array } [ c]{c}1\\ 0\\ 0\\ \left ( 1-\gamma\right ) ^{2}\end{array } \right ) \text{.}\ ] ] applying the gram - schmidt orthonormalization procedure to @xmath416 , we get@xmath417{c}0\\ 1\\ 1\\ 0 \end{array } \right ) \text { , } \left\vert e_{2}\right\rangle \overset{\text{def}}{=}\frac{1}{\sqrt{2}}\left ( \begin{array } [ c]{c}0\\ -1\\ 1\\ 0 \end{array } \right ) \text { , } \left\vert e_{3}\right\rangle \overset{\text{def}}{=}\frac{1}{\sqrt{2}}\frac{1}{\sqrt{\frac{1+\left ( 1-\gamma\right ) ^{4}}{2}}}\left ( \begin{array } [ c]{c}-\left ( 1-\gamma\right ) ^{2}\\ 0\\ 0\\ 1 \end{array } \right ) \text { , } \nonumber\\ & \nonumber\\ \left\vert e_{4}\right\rangle \overset{\text{def}}{=}\frac{a_{0000}p_{\mathcal{c}}\left\vert v_{4}\right\rangle } { \lambda_{4 } } & = \frac { 1}{\sqrt{2}}\frac{1}{\sqrt{\frac{1+\left ( 1-\gamma\right ) ^{4}}{2}}}\left ( \begin{array } [ c]{c}1\\ 0\\ 0\\ \left ( 1-\gamma\right ) ^{2}\end{array } \right ) \text { , } \label{e}\ ] ] with @xmath418 . finally , the unitary operator @xmath412 reads,@xmath419 that is , using eqs . ( [ cafe1 ] ) and ( [ e]),@xmath420{cccc}\frac{1}{\sqrt{2}}\frac{1+\left ( 1-\gamma\right ) ^{2}}{\sqrt{1+\left ( 1-\gamma\right ) ^{4 } } } & 0 & 0 & \frac{1}{\sqrt{2}}\frac{1-\left ( 1-\gamma\right ) ^{2}}{\sqrt{1+\left ( 1-\gamma\right ) ^{4}}}\\ 0 & 1 & 0 & 0\\ 0 & 0 & 1 & 0\\ -\frac{1}{\sqrt{2}}\frac{1-\left ( 1-\gamma\right ) ^{2}}{\sqrt{1+\left ( 1-\gamma\right ) ^{4 } } } & 0 & 0 & \frac{1}{\sqrt{2}}\frac{1+\left ( 1-\gamma\right ) ^{2}}{\sqrt{1+\left ( 1-\gamma\right ) ^{4}}}\end{array } \right ) \text{. } \label{uuu}\ ] ] finally , the leung et _ al_. recovery operator associated with the enlarged error operator @xmath281 is given by,@xmath421 with @xmath52 in eq . ( [ pa ] ) and @xmath412 in eq . ( [ uuu ] ) . let @xmath28 be a @xmath29 \right ] $ ] quantum stabilizer code that spans a @xmath422-dimensional subspace of a @xmath423-dimensional hilbert space . two quantum codes @xmath424 and @xmath425 are _ locally permutation equivalent _ if @xmath426 with @xmath427 where @xmath428 is a local unitary transformation in @xmath429 and @xmath430 is a permutation of the qubits . when @xmath431 with @xmath432 , we say that the two quantum codes are _ locally equivalent_. finally , we say that the two codes are globally equivalent , or simply equivalent , if @xmath433 is locally equivalent to a code obtained from @xmath425 by a permutation on qubits . assuming single - qubit encoding , how many pairs @xmath434 @xcite , @xmath435 of orthonormal self - complementary codewords can we construct in the _ complex _ hilbert space @xmath27 ? to be explicit , recall that the canonical computational basis of @xmath27 reads,@xmath436{c}\left\vert e_{0000}\right\rangle \overset{\text{def}}{=}\left\vert 0000\right\rangle \text{,}\left\vert e_{1000}\right\rangle \overset { \text{def}}{=}\left\vert 1000\right\rangle \text { , } \left\vert e_{0100}\right\rangle \overset{\text{def}}{=}\left\vert 0100\right\rangle \text { , } \left\vert e_{0010}\right\rangle \overset{\text{def}}{=}\left\vert 0010\right\rangle \text{,}\\ \text { } \left\vert e_{0001}\right\rangle \overset{\text{def}}{=}\left\vert 0001\right\rangle \text { , } \left\vert e_{1100}\right\rangle \overset { \text{def}}{=}\left\vert 1100\right\rangle \text{,}\left\vert e_{1010}\right\rangle \overset{\text{def}}{=}\left\vert 1010\right\rangle \text { , } \left\vert e_{1001}\right\rangle \overset{\text{def}}{=}\left\vert 1001\right\rangle \text { , } \left\vert e_{0110}\right\rangle \overset { \text{def}}{=}\left\vert 0110\right\rangle \text{,}\\ \text { } \left\vert e_{0101}\right\rangle \overset{\text{def}}{=}\left\vert 0101\right\rangle \text{,}\left\vert e_{0011}\right\rangle \overset { \text{def}}{=}\left\vert 0011\right\rangle \text{,}\left\vert e_{1110}\right\rangle \overset{\text{def}}{=}\left\vert 1110\right\rangle \text { , } \left\vert e_{1101}\right\rangle \overset{\text{def}}{=}\left\vert 1101\right\rangle \text { , } \left\vert e_{0111}\right\rangle \overset { \text{def}}{=}\left\vert 0111\right\rangle \text{,}\\ \left\vert e_{1011}\right\rangle \overset{\text{def}}{=}\left\vert 1011\right\rangle \text { , } \left\vert e_{1111}\right\rangle \overset { \text{def}}{=}\left\vert 1111\right\rangle \text { } \end{array } \right\ } \text{.}\ ] ] the number of possible pairs is,@xmath437 and they are given by,@xmath438 where,@xmath439 thus , the possible combinations are@xmath440 it turns out that among the @xmath441-pairs of possible self - complementary orthogonal codewords in @xmath27 , only three pairs are indeed good single - ad error correcting codes . for more details , see part @xmath284 of appendix c. they are given by : * the @xmath442-pair that represents the leung et _ @xmath443 \right ] $ ] -code . the non - normalized codewords read,@xmath444 * the @xmath445-pair that represents the grassl et _ al_. perfect quantum erasure code . the non - normalized codewords read,@xmath446 * the @xmath447-pair has no specific mention in the literature , to the best of our knowledge . the non - normalized codewords read,@xmath448 the three codes spanned by the codewords in ( [ a ] ) , ( [ b ] ) and ( [ c ] ) are indeed globally equivalent . we point out that the codeword @xmath449 is the only codeword in these @xmath26-pairs that is invariant under any cyclical permutation of qubits . this property of @xmath24 turns out to be very useful when checking out the global equivalence among the three good single - ad error correcting codes . in particular , the leung et _ @xmath443 \right ] $ ] -code is globally equivalent to the grassl et _ al . _ perfect quantum erasure code encoding one qubit and correcting one arbitrary erasure . observe that for the leung et _ al_. four - qubit code ( normalization factors are omitted ) , we have@xmath450 for the grassl et _ al_. four - qubit code ( normalization factors are omitted ) , we get@xmath451 finally , for the third * * four - qubit code defined in eq . ( [ c ] ) ( normalization factors are omitted ) , we obtain@xmath452 from eqs . ( [ unos ] ) , ( [ du ] ) and ( [ tres ] ) it is straightforward to show that the pairs @xmath453 , @xmath454 and @xmath447 , respectively , lead to good codes for the ad errors . finally , it can be checked that,@xmath455 and,@xmath456 finally , we have that@xmath457 in this appendix , we use the notation @xmath458 and @xmath459 . the problem is to find @xmath460 and @xmath461 ( perhaps @xmath342-dependent quantities ) such that @xmath462 denotes the searched maximum,@xmath463 let us precede by brute force in an analytical fashion . assume that,@xmath464 therefore , the two _ complex_-variables complex optimization problem may be defined in terms of four _ real_-variables optimization problem,@xmath465 observe that @xmath345 \right ] } \left ( \alpha\text { , } \beta\text { , } \gamma\right ) $ ] can be rewritten as , @xmath344 \right ] } \left ( \gamma\right ) \left ( \alpha\text { , } \beta\text { , } \gamma\right ) = \frac{1}{4}\left\ { a+b+2\gamma\left ( 1-\gamma\right ) \left ( 2-\gamma\right ) ^{2}+2\gamma ^{2}\left ( 1-\gamma\right ) ^{2}+\frac{\gamma^{4}}{2}\right\ } \text { , } \label{amo}\ ] ] where,@xmath466 and,@xmath467 after some algebraic manipulation of eqs . ( [ xx ] ) and ( [ x ] ) , we get@xmath468 + \nonumber\\ & \nonumber\\ & + \left [ \left ( \frac{\alpha_{i}+\beta_{i}\left ( 1-\gamma\right ) ^{2}}{\sqrt{2}}\right ) ^{2}+\left ( \frac{\beta_{i}-\alpha_{i}\left ( 1-\gamma\right ) ^{2}}{\sqrt{2}}\right ) ^{2}\right ] \nonumber\\ & \nonumber\\ & = \left [ \left ( \alpha_{r}^{2}+\beta_{r}^{2}\right ) \left ( \frac{1+\left ( 1-\gamma\right ) ^{4}}{2}\right ) + \left ( 1-\gamma\right ) ^{2}+2\left ( 1-\gamma\right ) \frac{\alpha_{r}+\beta_{r}\left ( 1-\gamma\right ) ^{2}}{\sqrt{2}}\right ] + \nonumber\\ & \nonumber\\ & + \left [ \left ( \alpha_{i}^{2}+\beta_{i}^{2}\right ) \left ( \frac{1+\left ( 1-\gamma\right ) ^{4}}{2}\right ) \right ] \nonumber\\ & \nonumber\\ & = \frac{1+\left ( 1-\gamma\right ) ^{4}}{2}+\left ( 1-\gamma\right ) ^{2}+2\left ( 1-\gamma\right ) \frac{\alpha_{r}+\beta_{r}\left ( 1-\gamma\right ) ^{2}}{\sqrt{2}}\text{. } \label{chistu}\ ] ] therefore , substituting ( [ chistu ] ) into ( [ amo ] ) , @xmath391 \right ] } \left ( \alpha\text { , } \beta\text { , } \gamma\right ) $ ] becomes@xmath379 \right ] } \left ( \alpha_{r}\text { , } \alpha_{i}\text { , } \beta_{r}\text { , } \beta_{i}\text { , } \gamma\right ) & = \frac{1}{4}\left\ { \begin{array } [ c]{c}\frac{1+\left ( 1-\gamma\right ) ^{4}}{2}+\left ( 1-\gamma\right ) ^{2}+2\left ( 1-\gamma\right ) \frac{\alpha_{r}+\beta_{r}\left ( 1-\gamma\right ) ^{2}}{\sqrt{2}}+2\gamma\left ( 1-\gamma\right ) \left ( 2-\gamma\right ) ^{2}+\\ \\ + 2\gamma^{2}\left ( 1-\gamma\right ) ^{2}+\frac{\gamma^{4}}{2}\end{array } \right\ } \nonumber\\ & \nonumber\\ & = \mathcal{f}_{0}\left ( \gamma\right ) + \frac{2\alpha_{r}\left ( 1-\gamma\right ) + 2\beta_{r}\left ( 1-\gamma\right ) ^{3}}{4\sqrt{2}}\text{,}\ ] ] where,@xmath469 therefore , the _ complex _ optimization problem becomes@xmath379 \right ] } \left ( \bar{\alpha}_{r}\text { , } \bar{\alpha}_{i}\text { , } \bar{\beta}_{r}\text { , } \bar{\beta}_{i}\text { , } \gamma\right ) & = \underset{\bar{\alpha}_{r}^{2}+\bar{\alpha } _ { i}^{2}+\bar{\beta}_{r}^{2}+\bar{\beta}_{i}^{2}=1}{\max}\mathcal{f}_{\left [ \left [ 4,1\right ] \right ] } \left ( \alpha_{r}\text { , } \alpha_{i}\text { , } \beta_{r}\text { , } \beta_{i}\text { , } \gamma\right ) \nonumber\\ & \nonumber\\ & = \underset{\bar{\alpha}_{r}^{2}+\bar{\alpha}_{i}^{2}+\bar{\beta}_{r}^{2}+\bar{\beta}_{i}^{2}=1}{\max}\left [ \mathcal{f}_{0}\left ( \gamma\right ) + \frac{2\alpha_{r}\left ( 1-\gamma\right ) + 2\beta_{r}\left ( 1-\gamma\right ) ^{3}}{4\sqrt{2}}\right ] \text{.}\ ] ] we note that @xmath345 \right ] } \left ( \alpha_{r}\text { , } \alpha_{i}\text { , } \beta_{r}\text { , } \beta_{i}\text { , } \gamma\right ) $ ] does not depend on @xmath470 and @xmath471 . setting @xmath470 @xmath472 @xmath473 , the maximization problem becomes@xmath344 \right ] } \left ( \bar{\alpha}_{r}\text { , } \bar{\beta}_{r}\text { , } \gamma\right ) = \underset{\bar{\alpha } _ { r}^{2}+\bar{\beta}_{r}^{2}=1}{\max}\left [ \mathcal{f}_{0}\left ( \gamma\right ) + \frac{2\alpha_{r}\left ( 1-\gamma\right ) + 2\beta_{r}\left ( 1-\gamma\right ) ^{3}}{4\sqrt{2}}\right ] \text{.}\ ] ] we observe that,@xmath474 implies that,@xmath475 that is,@xmath476 finally , we obtain@xmath344 \right ] } \left ( \bar{\alpha}_{r}\text { , } \bar{\beta}_{r}\text { , } \gamma\right ) \overset{\gamma\ll 1}{\approx}1-\frac{3}{2}\gamma^{2}+\mathcal{o}\left ( \gamma^{3}\right ) \text{.}\ ] ] more precisely , we should set @xmath477 or , @xmath478 with @xmath479 . in this case we have,@xmath480 that is , @xmath344 \right ] } \left ( \bar{\alpha}_{r}\text { , } \bar{\beta}_{r}\text { , } \gamma\right ) = \underset{\bar{\alpha } _ { r}^{2}+\bar{\beta}_{r}^{2}=r^{2}}{\max}\left [ \mathcal{f}_{0}\left ( \gamma\right ) + \frac{2\alpha_{r}\left ( 1-\gamma\right ) + 2\beta_{r}\left ( 1-\gamma\right ) ^{3}}{4\sqrt{2}}\right ] \text{,}\ ] ] that is,@xmath482 thus,@xmath344 \right ] } \left ( \bar{\alpha}_{r}\text { , } \bar{\beta}_{r}\text { , } \gamma\right ) \approx\frac{1}{2}\left ( 1+r\right ) + \left ( 1-r\right ) \gamma-\left ( \frac{5}{2}-r^{2}\right ) \gamma^{2}+\mathcal{o}\left ( \gamma^{3}\right ) \text{.}\ ] ] it then turns out that for @xmath483 we obtain the optimal fidelity,@xmath344 \right ] } \left ( \bar{\alpha}_{r}\text { , } \bar{\beta}_{r}\text { , } \gamma\right ) \approx1-\frac{3}{2}\gamma^{2}+\mathcal{o}\left ( \gamma^{3}\right ) \text{.}\ ] ] in conclusion , setting @xmath470 @xmath472 @xmath473 and @xmath484 , @xmath485 given in eq . ( c16 ) , @xmath345 \right ] } \left ( \alpha\text { , } \beta\text { , } \gamma\right ) $ ] in ( [ amo ] ) becomes @xmath344 \right ] } ^{\text{f - recovery}}\left ( \gamma\right ) \approx1-\frac{3}{2}\gamma^{2}+\mathcal{o}\left ( \gamma ^{3}\right ) \text{. } \label{finale}\ ] ] the derivation of eq . ( [ finale ] ) concludes our optimization problem . we emphasize that after completing this work , we have become aware that eq . ( [ finale ] ) has also appeared in @xcite . however , the derivation presented in @xcite is by no means as explicit as the one provided in our work . d. gottesman , _ an introduction to quantum error correction and fault - tolerant quantum computation _ , in quantum information science and its contributions to mathematics , proceedings of symposia in applied mathematics * 68 * , pp . 13 - 58 , amer . soc . , providence , rhode island , usa ( 2010 ) . r. duan , m. grassl , z. ji , and b. zeng , _ multi - error - correcting amplitude damping codes _ , proceedings of ieee international symposium on information theory , june 2010 , austin - usa , pp . 2672 - 2676 ( 2010 ) .

we present a comparative analysis of exact and approximate quantum error correction by means of simple unabridged analytical computations . for the sake of clarity , using primitive quantum codes , we study the exact and approximate error correction of the two simplest unital ( pauli errors ) and nonunital ( non - pauli errors ) noise models , respectively . the similarities and differences between the two scenarios are stressed . in addition , the performances of quantum codes quantified by means of the entanglement fidelity for different recovery schemes are taken into consideration in the approximate case . finally , the role of self - complementarity in approximate quantum error correction is briefly addressed .

SECTION 1. SHORT TITLE. This Act may be cited as the ``Matewan Flood Control Excess Project Land Disposal Act of 1999''. SEC. 2. DISPOSITION OF EXCESS PROPERTY. (a) In General.--The United States shall convey by quit claim deed to the Town of Matewan, West Virginia, all right, title, and interest of the United States in and to four parcels of land deemed excess by the Secretary of the Army, acting through the Chief of the U.S. Army Corps of Engineers, to the structural project for flood control constructed by the Corps of Engineers along the Tug Fork River pursuant to section 202 of Public Law 96-367. (b) Property Description.--The parcels of land referred to in subsection (a) are as follows-- (1) A certain parcel of land in the State of West Virginia, Mingo County, Town of Matewan, and being more particularly bounded and described as follows: Beginning at a point on the southerly right-of-way line of a 40-foot-wide street right-of-way (known as McCoy Alley), having an approximate coordinate value of N228,695, E1,662,397, in the line common to the land designated as U.S.A. Tract No. 834, and the land designated as U.S.A. Tract No. 837, said point being South 51 deg.52' East 81.8 feet from an iron pin and cap marked M-12 on the boundary of the Matewan Area Structural Project, on the north right-of-way line of said street, at a corner common to designated U.S.A. Tracts Nos. 834 and 836; thence, leaving the right-of- way of said street, with the line common to the land of said Tract No. 834, and the land of said Tract No. 837, South 14 deg.37' West 46 feet to the corner common to the land of said Tract No. 834, and the land of said Tract No. 837; thence, leaving the land of said Tract No. 837, severing the lands of said Project, South 14 deg.37' West 46 feet, South 68 deg.07' East 239 feet, North 26 deg.05' East 95 feet to a point on the southerly right-of-way line of said street; thence, with the right-of-way of said street, continuing to sever the lands of said Project, South 63 deg.55' East 206 feet; thence, leaving the right-of-way of said street, continuing to sever the lands of said Project, South 26 deg.16' West 63 feet; thence, with a curve to the left having a radius of 70 feet, a delta of 33 deg.58', an arc length of 41 feet, the chord bearing, South 09 deg.17' West 41 feet; thence, leaving said curve, continuing to sever the lands of said Project, South 07 deg.42' East 31 feet to a point on the right-of-way line of the floodwall; thence, with the right-of-way of said floodwall, continuing to sever the lands of said Project, South 77 deg.04' West 71 feet, North 77 deg.10' West 46 feet, North 67 deg.07' West 254 feet, North 67 deg.54' West 507 feet, North 57 deg.49' West 66 feet to the intersection of the right-of-way line of said floodwall with the southerly right-of-way line of said street; thence, leaving the right-of-way of said floodwall and with the southerly right-of-way of said street, continuing to sever the lands of said Project, North 83 deg.01' East 171 feet, North 89 deg.42' East 74 feet, South 83 deg.39' East 168 feet, South 83 deg.38' East 41 feet, South 77 deg.26' East 28 feet to the point of beginning, containing 2.59 acres, more or less. The bearings and coordinate used herein are referenced to the West Virginia State Plane Coordinate System, South Zone. (2) A certain parcel of land in the State of West Virginia, Mingo County, Town of Matewan, and being more particularly bounded and described as follows: Beginning at an iron pin and cap designated Corner No. M2-2 on the southerly right-of-way line of the Norfolk and Western Railroad, having an approximate coordinate value of N228,755 E1,661,242, and being at the intersection of the right-of-way line of the floodwall with the boundary of the Matewan Area Structural Project; thence, leaving the right-of-way of said floodwall and with said Project boundary, and the southerly right-of-way of said Railroad, North 59 deg.45' East 34 feet, North 69 deg.50' East 44 feet, North 58 deg.11' East 79 feet, North 66 deg.13' East 102 feet, North 69 deg.43' East 98 feet, North 77 deg.39' East 18 feet, North 72 deg.39' East 13 feet to a point at the intersection of said Project boundary, and the southerly right-of-way of said Railroad, with the westerly right-of-way line of State Route 49/10; thence, leaving said Project boundary, and the southerly right-of-way of said Railroad, and with the westerly right-of-way of said road, South 03 deg.21' East 100 feet to a point at the intersection of the westerly right-of-way of said road with the right-of-way of said floodwall; thence, leaving the right-of-way of said road, and with the right-of-way line of said floodwall, South 79 deg.30' West 69 feet, South 78 deg.28' West 222 feet, South 80 deg.11' West 65 feet, North 38 deg.40' West 14 feet to the point of beginning, containing 0.53 acre, more or less. The bearings and coordinate used herein are referenced to the West Virginia State Plane Coordinate System, South Zone. (3) A certain parcel of land in the State of West Virginia, Mingo County, Town of Matewan, and being more particularly bounded and described as follows: Beginning at a point on the southerly right-of-way line of the Norfolk and Western Railroad, having an approximate coordinate value of N228,936 E1,661,672, and being at the intersection of the easterly right-of- way line of State Route 49/10 with the boundary of the Matewan Area Structural Project; thence, leaving the right-of-way of said road, and with said Project boundary, and the southerly right-of-way of said Railroad, North 77 deg.49' East 89 feet to an iron pin and cap designated as U.S.A. Corner No. M-4, North 79 deg.30' East 74 feet to an iron pin and cap designated as U.S.A. Corner No. M-5-1; thence, leaving the southerly right-of-way of said Railroad, and continuing with the boundary of said Project, South 06 deg.33' East 102 to an iron pipe and cap designated U.S.A. Corner No. M-6-1 on the northerly right-of-way line of State Route 49/28; thence, leaving the boundary of said Project, and with the right-of-way of said road, severing the lands of said Project, North 80 deg.59' West 171 feet to a point at the intersection of the Northerly right-of-way line of said State Route 49/28 with the easterly right-of-way line of said State Route 49/10; thence, leaving the right- of-way of said State Route 49/28 and with the right-of- way of said State Route 49/10, North 03 deg.21' West 42 feet to the point of beginning, containing 0.27 acre, more or less. The bearings and coordinate used herein are referenced to the West Virginia State Plane Coordinate System, South Zone. (4) A certain parcel of land in the State of West Virginia, Mingo County, Town of Matewan, and being more particularly bounded and described as follows: Beginning at a point at the intersection of the easterly right-of-way line of State Route 49/10 with the right-of-way line of the floodwall, having an approximate coordinate value of N228,826 E1,661,679; thence, leaving the right-of-way of said floodwall, and with the right-of-way of said State Route 49/10, North 03 deg.21' West 23 feet to a point at the intersection of the easterly right-of-way line of said State Route 49/10 with the southerly right-of-way line of State Route 49/28; thence, leaving the right-of-way of said State Route 49/10 and with the right-of-way of said State Route 49/28, South 80 deg.59' East 168 feet, North 82 deg.28' East 45 feet to an iron pin and cap designated as U.S.A. Corner No. M-8-1 on the boundary of the Western Area Structural Project; thence, leaving the right-of-way of said State Route 49/28, and with said Project boundary, South 08 deg.28' East 88 feet to an iron pin and cap designated as U.S.A. Corner No. M-9-1 point on the northerly right-of-way line of a street (known as McCoy Alley); thence, leaving said Project boundary and with the northerly right-of-way of said street, South 83 deg.01' West 38 feet to a point on the right-of-way line of said floodwall; thence, leaving the right-of-way of said street, and with the right-of- way of said floodwall, North 57 deg.49' West 180 feet, South 79 deg.30' West 34 feet to a point of beginning, containing 0.24 acre, more or less. The bearings and coordinate used herein are referenced to the West Virginia State Plane Coordinate System, South Zone.

Matewan Flood Control Excess Project Land Disposal Act of 1999 - Directs the United States to convey to the Town of Matewan, West Virginia, four specified parcels of land deemed excess by the Secretary of the Army, acting through the Chief of the U.S. Army Corps of Engineers, to the structural project for flood control constructed by the Corps along the Tug Fork River.

low - mass x - ray binaries ( lmxbs ) are systems in which a low - mass donor star transfers mass via roche - lobe overflow onto a neutron star ( ns ) or black hole ( bh ) . many of the lmxbs are transient systems . these transients undergo occasional outbursts during which they typically reach peak luminosities of @xmath30.011 times the eddington luminosity ( @xmath10 ) , but they spend most of their time in quiescence , with much lower luminosities . here we adopt the definition of quiescence ( for bh lmxbs ) by @xcite , @xmath11 . we note that finding a source at @xmath12 does not necessarily mean that a source is detected at its minimum quiescent luminosity , as sources have been found with @xmath13 as low as a few times @xmath14 @xcite . the nature of the accretion flow in quiescence is still a matter of debate . proposed explanations for the very low quiescent luminosities include radiatively inefficient flows @xcite and low net accretion rates in the inner regions as the result of disk winds @xcite or jets @xcite . in the last decade , the high sensitivities of _ chandra _ and _ xmm - newton _ have opened up the possibility of detailed x - ray studies of quiescent lmxbs down to eddington ratios as low as @xmath3@xmath15 @xmath10 @xcite . these observations have revealed that , when comparing lmxbs with similar orbital periods ( @xmath16 ) , quiescent ns systems have on average higher luminosities than quiescent bh systems , by factors of @xmath310100 @xcite . this can clearly be seen in figure [ fig : orbital ] . it is important to consider systems with the same @xmath16 ; at a given @xmath16 bh and ns lmxbs are assumed to have similar quiescent mass accretion rates @xcite . expected mass transfer rates for quiescent bhs and nss were calculated by @xcite , and they showed that for quiescent lmxbs there should exist a minimum mass transfer rate that stems directly from the existence of a bifurcation orbital period , @xmath17 . below this period the mass transfer is driven by gravitational wave radiation and above it , it is dominated by the nuclear evolution of the secondary star . specifically , the mass transfer rate increases with decreasing orbital period below @xmath17 , while it increases with @xmath16 above @xmath17 . for a wide range of donor masses , the results of @xcite imply @xmath18510 hr for bhs and @xmath1835 hr for nss . the luminosity difference between quiescent bh and ns lmxbs has been interpreted as evidence for the presence of an event horizon in bh lmxbs @xcite , although it may also be the result of jet - dominated states in quiescent bh lmxbs @xcite . interestingly , the lowest - luminosity quiescent source currently known ( @xmath19 ergs@xmath1 ) is an ns lmxb , 1h 1905 + 000 @xcite . however , this source is likely an ultra - compact with an orbital period less than 80 minutes @xcite , and therefore falls in a @xmath16 range ( @xmath204 hr ) in which , until recently , no quiescent bh lmxbs had been observed . arrows indicate upper limits on luminosity or orbital period . based on data presented in @xcite , @xcite , and @xcite.,width=302 ] another result of the _ chandra _ and _ xmm - newton _ observations of quiescent lmxbs concerns the nature of the quiescent accretion flow in bh systems.the quiescent state of bh lmxbs has often been considered a low - luminosity extension of the so - called low - hard state . indeed , in terms of radio / x - ray flux correlations , which likely trace the evolution of the accretion ( in)flow and/or jet outflow , quiescent bh lmxbs appear to follow the main relation seen in the low - hard state @xcite . however , recent observations suggest that in terms of x - ray spectral shape considerable evolution occurs in the accretion flow as some sources approach quiescence @xcite , with spectral power - law photon indices that are steeper ( @xmath32.22.5 ) than those seen in the low - hard state ( @xmath31.5 ) . a recent study of the quiescent spectra of ten bh lmxbs by @xcite suggests that , once these sources reach @xmath21 , their spectra saturate at power - law indices of @xmath22 . based on their findings @xcite argue that quiescence does not appear to represent a distinct spectral state separated from the low - hard state . several mechanisms could be responsible for the observed steepening toward quiescence , such as , e.g. , a non - linear dependence of mass accretion rate on the inner - disk radius , as expected in the presence of outflows ( see discussion in * ? ? ? * ) , changes in the properties of a comptonizing corona @xcite , or the jet s cooling break shifting through the x - ray band @xcite . in this paper we present _ chandra _ observations of maxi j1659152 , an x - ray transient that was discovered in 2010 september with the _ swift _ burst alert telescope @xcite . although it was originally thought to be a gamma - ray burst , optical spectra obtained with the very large telescope / x - shooter @xcite and x - ray observations with _ @xcite strongly suggested that maxi j1659152 is an lmxb with a bh primary . during an outburst in 2010/2011 that lasted more than nine months , the source was extensively observed with various x - ray @xcite , optical / near - infrared @xcite and radio observatories @xcite . these observations revealed that the source made several state transitions and showed behavior similar to that seen in many other transient bh lmxbs . the distance to maxi j1659152 has been estimated using various methods , with a most likely range of 4.58.5 kpc @xcite . following @xcite , we adopt a distance of 6 kpc in this paper . _ xmm - newton _ and _ swift _ observations made during the rise and maximum of the outburst revealed the presence of dips in the x - ray light curves , from which an orbital period of [email protected] hr was derived @xcite . this makes maxi j1659152 the bh lmxb with the shortest known orbital period . such a short orbital period is of particular interest to one of the issues described earlier : the difference between ns and bh quiescent luminosities at low @xmath16 . maxi j1659152 was already observed with _ chandra _ during the initial decay of its outburst , a subsequent three - month reflare , and soon after the source appeared to have reached quiescence . the results of these observations were reported by @xcite . they found the source in a quiescent state during most of their observations . the minimum quiescent luminosity of maxi j1659152 was determined from two observations taken shortly after the reflare ; it falls at the high end of what is expected for its orbital period ( assuming a distance of 6 kpc ) , although it is still fainter than quiescent ns lmxbs with similar @xmath16 values . one explanation for this higher than expected luminosity could be that at the time of the last _ chandra _ observations the source still had not reached its minimum quiescent luminosity . the new _ chandra _ observations presented here were made about a year after the source had entered quiescence . they allow us to test whether the quiescent luminosity reported by @xcite was close to a minimum luminosity , or if the source had declined even further . we also present a more detailed study of the spectral softening in maxi j1659152 . maxi j1659152 has been observed eight times with _ chandra_. a log of the observations can be found in table [ tab : obs ] . all observations were made with the back - illuminated s3 ccd chip of the advanced ccd imaging spectrometer ( acis ; * ? ? ? * ) . the first six observations were already analyzed by @xcite . two new observations , made in 2012 july , were added to the analysis presented in this work . observations 68 were made in vfaint mode , which allows for better background cleaning , while the others were made in faint mode . all observations were analyzed using ciao 4.4 , caldb 4.5.5.1 , and acis extract version 2012nov1 @xcite . as a first step , the chandra@xmath24repro script was run to reprocess the data from all the observations . the data were checked for episodes of enhanced background , but none were found . images in the 0.57.0 kev band were extracted for each observation to search for extended emission . further analysis was performed with the help of acis extract . [ cols="^,^,^,^,^,^,^,^ " , ] * notes . * errors on the fit parameters reflect the 1@xmath25 uncertainties . + @xmath26unabsorbed flux in the 0.510 kev band . + @xmath27these observations were fitted together with power - law indices linked . + @xmath28pile - up model parameter alpha is 0.11 @xmath23 0.10 . source spectra were extracted from near - circular polygon - shaped regions modeled on the _ chandra _ acis point - spread function ( psf ) . the source extraction regions had a psf enclosed energy fraction of @xmath30.97 ( for a photon energy of @xmath31.5 kev ) and a radius of @xmath319 , except for the extraction region for observation 4 , which had an enclosed energy fraction of @xmath30.98 and a radius of @xmath327 ( due to the higher count rate ) . for the background extraction regions we used annuli centered around the source , with inner radii of @xmath344 ( 22 for observation 4 ) and outer radii of 2425 ( 455 for observation 4 ) . a circular region with a radius of @xmath343 centered around the source to the north - east of maxi j1659152 ( cxou j165902.6151518 ; see figure [ fig : image ] ) was excluded from the background region . for observation 4 we excluded an additional 10@xmath2980 rectangle surrounding the read - out streak from the background region . response files were created using the mkacisrmf and mkarf tools in ciao . the spectra were fitted in the 0.37.0 kev range with xspec 12.7.1 @xcite . given the low number of source counts per spectrum ( as low as 10 ) , we used the c statistic @xcite , modified to account for the subtraction of background counts , the so - called w statistic . the spectra were grouped to at least one photon per spectral bin . following @xcite all spectra were fitted with an absorbed power law ( tbabs*pegpwrlw in xspec ) , with the abundances set to wilm and the cross sections set to vern . because of high count rates ( see table [ tab : obs ] ) , for observation 4 we also added the pile - up model of @xcite . the @xmath30 was first determined from fits to the spectrum of observation 4 , which had the highest number of counts , and subsequently it was fixed in all spectral fits . we obtained a value of 0.33(2)@xmath31 atoms@xmath2 , which is somewhat higher than the value of 0.23@xmath31 atoms@xmath2 used by @xcite ( see also * ? ? ? * ) . to put to our _ chandra _ observations in the context of the full outburst decay , we also constructed a 0.310 kev light curve from archival _ swift_/xrt observations , using the online _ swift_/xrt data products generator @xcite . for our _ chandra _ observations , corresponding _ swift_/xrt 0.310 kev count rates were calculated from our _ chandra _ spectra , by simulating _ swift_/xrt spectra based on the best - fit model parameters and using _ swift_/xrt response files . all the 0.57 kev band images were visually inspected for possible features close to maxi j1659152 that could be related to jet outflows , such as those seen in xte j1550564 @xcite , h 1743322 @xcite , and possibly xte j1752223 @xcite . none could be seen . we also created a combined image from 7 of the 8 observations to increase sensitivity ; observation 4 was excluded from this because of the prominent read - out streak . the total exposure time for the resulting image , which is shown in figure [ fig : image ] , is @xmath3219 ks . again , no obvious jet - related structures could be identified . table [ tab : obs ] lists the results of our spectral fits . since they had similar count rates , the spectra of observations 3 and 58 were fitted simultaneously with their power - law indices tied , as the power - law indices would otherwise be poorly constrained ; the normalizations were left free to vary independently . the unabsorbed 0.510 kev fluxes measured during the two new _ chandra _ observations ( 7 and 8) of maxi j1659152 are @xmath32 ergs@xmath1@xmath2 and @xmath33 ergs@xmath1@xmath2 . since observations 7 and 8 were taken only a few days apart , we also made a fit with the normalizations of the power - law component tied , which resulted in a flux of @xmath0 ergs@xmath1@xmath2 . we find power - law indices between @xmath31.5 and @xmath32.5 . there appears to be a correlation between the slope of the power law and the flux , as can be seen from table [ tab : obs ] and figure [ fig : pli ] ; the power law steepens as the flux decreases . a fit to the spectral index versus flux relation in figure [ fig : pli ] with a constant index is significantly worse ( @xmath34/dof=14.1/3 ) than one with a power - law ( @xmath34/dof=1.00/2 ) . we note that the power - law indices reported here are somewhat higher than the values reported in @xcite , although they are consistent at the 1@xmath25 level individually . this is likely the result of our much smaller source extraction regions ( @xmath32instead of 10 ) and the higher @xmath30 value that we used in our fits . in figure [ fig : curve ] we show the combined _ swift _ and _ chandra _ light curve of maxi j1659152 . chandra _ data are shown in red . the dashed horizontal line shows the count rate level corresponding to the average flux in the last two _ chandra _ observations . around day 200 maxi j1659152 showed an initial decline towards quiescence . this decline was rapid , with an exponential decay time scale of [email protected] days ( fitted to the first three _ chandra _ observations , plus the _ swift _ observation near day 200 ) . the best - fit exponential decay is shown as a gray diagonal line . the source had nearly reached the quiescent level at the time of the third _ chandra _ observation . however , shortly thereafter it showed a nearly 90-day reflare @xcite , during which the flux went up by a factor of @xmath33000 . the second decay was rapid as well ; a fit to the two _ swift _ data points before the fifth _ chandra _ observation yields an exponential decay time scale of 4.8 @xmath23 0.9 days , hence the @xmath35-folding times are consistent with being the same . we have presented an analysis of _ chandra _ observations of maxi j1659152 . two new observations were analyzed in addition to the earlier six presented in @xcite and @xcite . these two observations were made more than 320 days after the end of the reflare that was observed at the end of the outburst of maxi j1659152 ( see figure [ fig : curve ] ) . while the flux of observations 7/8 is the lowest value observed in the quiescent state of maxi j1659152 , it is consistent ( within 1@xmath25 errors ) with the value measured in observation 5 , which was taken close to the end of the reflare . the flux of observation 6 was also within a factor of two of the flux seen in observations 7/8 . the five lowest fluxes seen with _ chandra _ ( obs . 3 , 5 , 6 , 7 + 8 ) all fall within a factor of @xmath32.5 of each other . combined with the fact that these fluxes were measured over a time span of @xmath3430 days , this suggests that this flux range ( 2.8(8)7(3)@xmath36 ergs@xmath1@xmath2 ) represents a relatively stable ( within a factor of @xmath32.5 ) minimum quiescent flux for maxi j1659152 . the average flux of observations 7/8 translates into a 0.510 kev luminosity of @xmath37 ( @xmath8 ergs@xmath1 , where the distance @xmath38 is likely in the range 4.58.5 kpc ( see section [ sec : intro ] ) . in figure [ fig : orbital ] we show the quiescent luminosities of ns ( stars ) and bh lmxbs ( circles ) as a function of @xmath16 ; maxi j1659152 is shown as an open circle . as can be seen from this figure there is a clear correlation between the quiescent luminosities of bh lmxbs and their @xmath16 , although there is substantial scatter . the quiescent luminosity of maxi j1659152 is relatively high compared to some of the systems in the @xmath16 range of 4.28.3 hr . this would still be true had we assumed a distance of 4.5 kpc , which would imply a luminosity of 6.8@xmath39 ergs@xmath1 . as mentioned in section [ sec : intro ] , the mechanism that drives the mass accretion in quiescence is expected to switch from gravitational - wave losses to evolution of the secondary star around a @xmath16 of @xmath3510 hr in bh lmxbs , depending on the mass of the secondary @xcite . as a result , the lowest quiescent bh luminosities are expected to be found in systems with a @xmath16 around 510 hr . based on the data presented in their paper , @xcite already suggested that such a minimum may exist at a limiting luminosity of a few times 10@xmath40 ergs@xmath1 . although the number of systems with @xmath16 of a few hours is still very small , the relatively high quiescent luminosity of maxi j1659152 , the shortest @xmath16 system , may be a further sign of the existence of a minimum quiescent luminosity for bh lmxbs , in a range consistent with that implied ( @xmath16@xmath3510 hr ) by the work of @xcite . additional support for the existence of a minimum quiescent luminosity for bh lmxbs may come from swift j1357.20933 , a very faint x - ray transient discovered in early 2011 @xcite . this system likely contains a bh @xcite and has a short orbital period of 2.8 hr @xcite . swift_/xrt observation at the end of the outburst , when the source was returning to or had returned to quiescence , yielded an upper limit on the 0.510 kev luminosity of 2@xmath41 ergs@xmath1 @xcite , for a distance of 1.5 kpc @xcite . swift j1357.20933 is shown as the gray data point in figure [ fig : orbital ] . this upper limit is close to the quiescent luminosity of maxi j1659152 , and about a decade higher than one would expect based on extrapolating the general trend seen for bh systems above @xmath16 = 4 hr . figure [ fig : pli ] shows a steepening of the spectrum as the flux decreases . this has previously been seen in other sources @xcite , but our observations of maxi j1659152 present one of the clearest examples of spectral softening as a source recedes into quiescence . our _ chandra _ observations of maxi j1659152 allow us to set constraints on the luminosity level at which this softening starts . in observation 4 , which showed the highest luminosity of our observations , the power - law index was found to be 1.55(4 ) , which is consistent with the indices seen in the hard state at the end of the outburst of maxi j1659152 @xcite . in the second brightest observation ( nr.1 ) , the index was already significantly higher at 1.87(12 ) . it is therefore likely that in maxi j1659152 the spectral softening started between 0.510 kev fluxes of @xmath42 ergs@xmath1@xmath2 ( obs.1 ) and @xmath43 ergs@xmath1@xmath2 ( obs.4 ) . this corresponds to fractional eddington luminosities ( @xmath44 ) ergs@xmath1 . ] of ( 0.186.2)@xmath45(@xmath8 ( @xmath9 ) . for xte j1550564 @xcite report an average power - law index of 2.25(8 ) in the 0.510 kev flux range of ( 794)@xmath46 ergs@xmath1@xmath2 . for a distance of 4.38 kpc and a bh mass of 9.1 @xmath47 @xcite this implies that the softening in xte j1550564 must have started above a fractional eddington luminosity of @xmath31.8@xmath48 . in h 1743322 an index of 2.2(6 ) was measured by @xcite at a 0.510 kev flux of 5.0(7)@xmath49 ergs@xmath1@xmath2 . for a distance of 8.5 kpc @xcite this implies that the softening must have started above a fractional eddington luminosity of 4.2@xmath48 ( @xmath9 ) . combining _ chandra _ data from ten quiescent bhs ( including the ones discusses above ) , @xcite find that softening is already ongoing around @xmath50 @xmath10 and plateaus around @xmath51 @xmath10 , similar to the range we find for maxi j1659152 . there are also various reports of softening of x - ray spectra toward quiescence based on _ rxte _ data ( see , e.g. , * ? ? ? * ; * ? ? ? * ; * ? ? ? * ; * ? ? ? * ; * ? ? ? these authors report that softening already starts at luminosities of @xmath52 @xmath10 , which is much higher than the luminosity range implied by maxi j1659152 . however , in several of these works @xcite the spectra were not corrected for galactic ridge emission , which provides a natural explanation for the observed softening ; the galactic ridge emission can be fitted with a power law with an index of @xmath32.14 @xcite , and an even higher index when an absorbed power law is used . simulations that we performed suggest that a ridge contribution of as little as 5% can already result in detectable softening in a typical _ rxte _ observation . in other works @xcite attempts were made to correct the spectra for the galactic ridge emission . we inspected _ swift_/xrt archival data of gro j165540 @xcite , gx 3394 , and h 1743332 ( both this work ) , taken around the same time as the _ rxte _ data , or covering the same luminosity range ; these data show no evidence for spectral softening occurring around @xmath53 @xmath10 . moreover , at a few times @xmath54 @xmath10 @xcite find a range of indices ( with _ rxte _ ) that is substantially higher ( @xmath31.72.5 ) then the average index found at a few times @xmath55 @xmath10 with _ chandra _ ( @xmath56 ; * ? ? ? * ) . we therefore suspect that the reports of spectral softening based on _ rxte _ data may not be reliable and they should therefore be regarded with some caution . as mentioned in section [ sec : intro ] , the softening of spectra in quiescence can be explained by a variety of models . quiescent spectra are generally not of sufficient quality for accurate spectral modeling ( beyond a simple power law ) and it is therefore difficult to test ( and distinguish between ) competing models for quiescent accretion flows . however , the observed softening ( and its relation with luminosity ) can possibly be used for this purpose . for example , @xcite showed that for convection - dominated accretion flows the softening in quiescence is expected to occur at luminosities below @xmath3@xmath57 @xmath10 , whereas our work shows that softening already starts at luminosities @xmath320600 times higher . the outburst light curve in figure [ fig : curve ] shows that maxi j1659152 had almost reached quiescence around day @xmath3220 . however , a major reflare , during which the luminosity increased by a factor of @xmath33000 , occurred soon after . while reflares ( or secondary maxima ) near the end of an outburst are not uncommon ( see , e.g. , * ? ? ? * ; * ? ? ? * ) , the magnitude of this reflare appears to be unusually high . this may be partly due to fact that the secondary maximum is well separated from the main outburst by a brief period of near - quiescence , whereas in other systems it occurred during ( the decay of ) the main outburst phase . given the short orbital period of the system it is possible that the secondary had undergone substantial x - ray heating of its outer layers , possibly resulting in a temporary increase in the mass transfer rate ( see , e.g. , * ? ? ? . finally , during its outburst maxi j1659152 showed spectral and timing signatures @xcite that suggested that the source had crossed the so - called `` jet line '' @xcite during its transition from the hard state to softer spectral states . such crossings have been associated with major ejection events , which are observed in the radio , but also on occasion in x - rays . although the outburst of maxi j1659152 has been monitored densely in radio , no radio flares were observed around the time at which maxi j1659152 crossed the jet line @xcite . our deep _ chandra _ images of maxi j1659152 do not reveal any indications for a major ejection event in x - rays either . j.h . would like to thank the members of the astronomical institute anton pannekoek " and sron utrecht , where part of this work was done , for their hospitality . this work made use of the uk swift science data centre at the university of leicester , nasa s astrophysics data system bibliographic services , of saoimage ds9 , developed by the smithsonian astrophysical observatory , and of software provided by the chandra x - ray center ( cxc ) in the application packages ciao . support for this work was provided by the national aeronautics and space administration through chandra award nos . go1 - 120498 and go2 - 13061x , issued by the chandra x - ray observatory center , which is operated by the smithsonian astrophysical observatory for and on behalf of the national aeronautics space administration under contract nas8 - 03060 . acknowledges support from a marie curie intra - european fellowship within the 7th european community framework programme under contract no . ief 274805 .

we present new _ chandra _ x - ray observations of the transient black hole x - ray binary maxi j1659152 in quiescence . these observations were made more than one year after the end of the source s 20102011 outburst . we detect the source at a 0.510 kev flux of @xmath0 ergs@xmath1@xmath2 , which corresponds to a luminosity of @xmath3@xmath4 @xmath5 ergs@xmath1 . this level , while being the lowest at which the source has been detected , is within factors of @xmath32 of the levels seen at the end of the initial decay of the outburst and soon after a major reflare of the source . the quiescent luminosity of maxi j1659152 , which is the shortest - orbital - period black hole x - ray binary ( @xmath32.4 hr ) , is lower than that of neutron - star x - ray binaries with similar periods . however , it is higher than the quiescent luminosities found for black hole x - ray binaries with orbital periods @xmath324 times longer . this could imply that a minimum quiescent luminosity may exist for black hole x - ray binaries , around orbital periods of @xmath3510 hr , as predicted by binary - evolution models for the mass transfer rate . compared to the hard state we see a clear softening of the power - law spectrum in quiescence , from an index of 1.55(4 ) to an index of 2.5(4 ) . we constrain the luminosity range in which this softening starts to @xmath6@xmath7 ( @xmath8 ( @xmath9 ) @xmath10 , which is consistent with the ranges inferred for other sources .

SECTION 1. SHORT TITLE. This Act may be cited as the ``Salt Cedar and Russian Olive Control Assessment and Demonstration Act''. SEC. 2. DEFINITIONS. In this Act: (1) Secretaries.--The term ``Secretaries'' means the Secretary of Agriculture, in cooperation with the Secretary of the Interior. (2) Western united states.--The term ``Western United States'' refers to the States defined by the Act of June 17, 1902 (commonly known as the 1902 Reclamation Act; 43 U.S.C. 371 et seq.), which includes Arizona, California, Colorado, Idaho, Kansas, Montana, Nebraska, Kansas, Oklahoma, Nevada, New Mexico, Oregon, Texas, Utah, Washington, and Wyoming. SEC. 3. ASSESSMENT OF SALT CEDAR AND RUSSIAN OLIVE INFESTATION IN WESTERN UNITED STATES. (a) Assessment.--Not later than one year after the date on which funds are first made available to carry out this section, the Secretaries shall complete an assessment of the extent of Salt Cedar and Russian Olive invasion in the Western United States. (b) Content.--The assessment shall include the following: (1) To the extent practicable, documentation of the quantity of water lost due to the infestation. (2) Documentation of the quantity of water saved due to various control methods, including the portion of saved water that returns to surface water or groundwater supplies and at what rates. (3) Determination of the optimum control method for the various land types and land uses. (4) Determination of what conditions indicate the need to remove such growth and the optimal methods for disposal or use of such growth. (5) Determination of methods to prevent the regrowth and reintroduction of Salt Cedar and Russian Olive and to reestablish native species. (c) Report on Assessment.-- (1) Preparation and content.--The Secretaries shall prepare a report containing the results of the assessment. The report shall identify long-term management and funding strategies that could be implemented by Federal, State, Tribal, and private land managers and owners on all land management types to address the invasion of Salt Cedar and Russian Olive. The report shall also identify deficiencies or areas for further study and where actual field demonstrations would be useful in the control effort. (2) Submission.--The Secretaries shall submit the report to the Committee on Resources and the Committee on Agriculture of the House of Representatives and the Committee on Agriculture, Nutrition, and Forestry and the Committee on Energy and Natural Resources of the Senate. (d) Support for Identification of Long-Term Management and Funding Strategies.--The Secretaries may make grants to institutions of higher education or nonprofit organizations (or both) with an established background and expertise in the public policy issues associated with the control of Salt Cedar and Russian Olive to obtain technical experience, support, and recommendations related to the identification of the long-term management and funding strategies required to be included in the report under subsection (c)(1). Each grant awarded under this subsection may not be less than $250,000. SEC. 4. DEMONSTRATION PROGRAM FOR CONTROL OF SALT CEDAR AND RUSSIAN OLIVE IN WESTERN STATES. (a) Demonstration Projects.-- (1) Projects required.--Based on the results of the assessment and report in section 3, the Secretaries shall initiate a program of not fewer than three demonstration projects in the Western United States designed to address the deficiencies and areas for further study to address the invasion of Salt Cedar and Russian Olive, including the test of additional control methods, identified by the report. (2) Implementation.--The Secretaries may enter into an agreement with a State in the Western United States to carry out a demonstration project. If the Secretaries select a demonstration project for implementation on National Forest System lands, the Secretary of Agriculture shall be responsible for implementation of the project. (b) Elements of Projects.-- (1) Design and scale.--Each demonstration project shall be designed with integrated methods and adaptive management strategies and carried out over time frames and spatial scales large enough to accomplish the goals laid out in the report. (2) Scientific review.--Before being carried out, the methods and strategies proposed for each demonstration project shall be subject to review by scientific experts, including non-Federal experts, selected by the Secretaries. The Secretaries may use existing scientific review processes to the extent they comply with this requirement. (c) Project Costs and Cost Sharing.--The total cost of each demonstration project may not exceed $7,000,000, including the costs of planning, design, implementation, revegetation, maintenance, and monitoring. In the case of a demonstration project conducted on lands under the jurisdiction of the Secretary of the Interior or the Secretary of Agriculture, the Secretaries may accept, but not require, funds or in-kind contributions, including State agency provided services. The Federal share of the costs of any activity on private lands funded under the project shall be no more than 75 percent of the total cost of the activity. (d) Reporting Requirement.--During the period in which the demonstration projects are carried out, the Secretaries shall submit to the congressional committees specified in section 3(c)(2) an annual report describing-- (1) the demonstration projects; (2) the progress made in carrying out the projects during the period covered by the report; and (3) the costs of the projects under subsection (c). (e) Monitoring.--Demonstration projects shall include the following: (1) Documentation of the quantity of water saved due to various control methods, including the portion of water saved that returns to surface water or groundwater supplies and at what rates. (2) Optimal revegetative states to prevent the regrowth and reintroduction of Salt Cedar and Russian Olive and to reestablish native species. (f) Cooperation.--The Secretaries shall use the expertise of their various agencies, as well as other Federal agencies, institutions of higher education, State and local governments and political subdivisions thereof, including soil and water conservation districts, and Indian tribes, which are actively conducting assessments on or implementing Salt Cedar and Russian Olive control activities. SEC. 5. RELATION TO OTHER AUTHORITY. Nothing in this Act shall be construed to affect, or otherwise bias, the use by the Secretaries of other statutory or administrative authorities to plan or conduct Salt Cedar or Russian Olive control and eradication that is not planned or conducted under this Act. SEC. 6. AUTHORIZATION OF APPROPRIATIONS. (a) Assessment.--There are authorized to be appropriated to the Secretaries $5,000,000 for fiscal year 2005 to conduct the assessment required by section 3. (b) Grants.--There are authorized to be appropriated to the Secretaries $1,000,000 for fiscal year 2005 to award as grants under section 3(d). (c) Demonstration Projects.--There are authorized to be appropriated to the Secretaries $18,000,000 for each of the fiscal years 2005 through 2009 to carry out the program of demonstration projects under section 4.

Salt Cedar and Russian Olive Control Assessment and Demonstration Act - Directs the Secretary of of Agriculture, in cooperation with the Secretary of the Interior, to assess the extent of Salt Cedar and Russian Olive invasion in the western United States. Directs the Secretaries to submit a report containing the results of such assessment and identifying: (1) long-term management and funding strategies; and (2) deficiencies or areas for further study and where actual field demonstrations would be useful in the control effort. Authorizes the Secretaries to make grants to institutions of higher education or nonprofit organizations (or both) in order to obtain technical experience, support, and recommendations related to the identification of the long-term management and funding strategies required to be included in such report. Directs the Secretaries to initiate a program of at least three demonstration projects in the western States designed to address deficiencies and areas for further study to address the invasion of Salt Cedar and Russian Olive. Sets forth required project elements.

the development of top - down cosmology has encountered a research hot on studying the superstring landscape for realizing the cosmological inflation . this involves the search of metastable de sitter - like string vacua at which the ten - dimensional spacetime behaves effectively as having only four dimensions , with six spatial extra dimensions compactified on a calabi - yau threefold and almost all of the compactification moduli including the calabi - yau volume stabilized . the advent of kklt mechanism@xcite for moduli stabilization has opened lots of possibilities to engineer inflation in string theory , using either the light closed string moduli@xcite or open string moduli@xcite related to the position of a mobile d - brane in wrapped geometry as the relevant scalar fields . different stringy realization of cosmological inflation may not be mutually incompatible . they may arise in different regions of the landscape , among which we anticipate that there is at least one possibility that realizes the inflationary evolution of our universe . the different inflation scenarios may also turn into one another , increasing the overall probability of inflation from a single mechanism@xcite . in a reasonable inflationary scenario , the inflaton field has to be ensured to roll its potential very slowly so that there are enough efoldings for acceleration . it is necessary that , during the inflation epoch , the potential energy curve of the involved scalars must be sufficiently flat and their effective masses have to be much smaller than the hubble parameter , @xmath4 . scalar fields such as the brane inter - distances in a general d - brane inflation model are conformally coupled to gravity , which enables them to acquire squared masses @xmath5 ( @xmath6-problem ) . to overcome this @xmath6-problem and have a slow - roll inflation in such a scenario , severe and sometimes unnatural fine - tunings are indispensable@xcite . alternatively , no severe @xmath6-problem exists in the closed string moduli inflation scenario@xcite where the inflation is thought of to be driven by some light closed string moduli associated with 4-cycle volumes of the compact calabi - yau threefolds , particularly in the large volume limit@xcite . the first proposed closed string moduli inflation scenarios in type iib superstring theory are the racetrack inflation model@xcite and the better racetrack inflation model@xcite , where the heavy moduli are stabilized at a supersymmetric anti - de sitter f - term potential minimum and the potential is uplifted to have a de sitter vacuum for inflation in an uncontrollable manner unless some additional ingredients are added to break the supersymmetry spontaneously@xcite . in the subsequent khler inflation model@xcite and roulette inflation model@xcite , the scalar potential for the moduli fields is calculated in the large volume limit , where the leading @xmath1-correction to the khler potential has been taken into account so that the heavy moduli are stabilized at a supersymmetric broken anti - de sitter f - term potential minimum . because this anti - de sitter minimum is apart from supersymmetry , it can be uplifted to a de sitter vacuum by taking into account some d - term corrections to the scalar potential@xcite . moreover , after heavy moduli are stabilized in the large volume limit , the scalar potential for the survived light khler moduli are exponentially flat , making such approaches very promising for engineering assisted - like inflation@xcite . in string theory cosmology scenario , the early evolution of our universe is essentially drived by multiple scalar fields . when superstring is compactified on a calabi - yau threefold to yield a four - dimensional effective @xmath7 supergravity theory , lots of moduli fields emerge . it has been conjectured , however , that increasing the number of khler moduli fields does probably make the inflation be easier to achieve@xcite . moreover , the presence of multiple scalar fields during inflation can lead to quite different inflationary dynamics such as the detectable non - gaussianity in primordial density perturbations on super - hubble scales and residual isocurvature fluctuations after inflation@xcite that might appear unnatural in a single field model . our aim in the present paper is to build a two - field inflation model from the large volume limit of type iib superstring with 3-form fluxes compactified on a calabi - yau orientifold of @xmath8 and discuss its implications on cobe spectrum of the linear curvature perturbation . for that we first investigate the possibility of realizing better racetrack inflation in the large volume approach . we divide the khler moduli into volume modulus , @xmath9 heavy moduli and two light moduli . the scalar potential is dominated by its f - term contribution , and is corrected by a volume - modulus dependent uplifting . the axion - dilaton , complex structure moduli and all heavy khler moduli including the volume modulus are stabilized , in the large volume limit , to a de sitter - like minimum of the potential , whereas the two light khler moduli remain dynamical during the moduli stabilization process . these two light khler moduli are supposed to be the scalar fields driving the inflationary expansion of the 4-dimensional universe . the de sitter minimum of the dominant potential does not only stabilize the heavy moduli by giving them masses , it governs also the evolution of two survived light moduli . the exponential dependence of the nonperturbatively corrected superpotential upon the khler moduli guarantees the flatness of the scalar potential for two light khler moduli . if the axionic components of the light moduli are dynamical , this is a large volume version of the better racetrack model@xcite in which four scalar fields are involved . in the present paper we choose to stabilize the axionic components at the potential minimum , a two - field assisted - like model@xcite results in instead . in some sense , this is an extension of the single field inflationary model@xcite to two - field case , to which we calculate the linear perturbations in a strict multi - field approach . by assigning some suitable model dependent parameters , we obtain the cobe normalization favored power spectrum of the linear curvature perturbation , and in particular , @xmath2 at the horizon exit . dependent upon the trajectory in phase space and thus the initial conditions we choose , the isocurvature perturbation in this model could decay very slowly for most of efolds on superhorizon scales . we have also observed that the power spectrum of curvature perturbation on the super - hubble scales has some remarkable departure from that of adiabatic perturbation at the end of inflation , implying that the curvature fluctuation after inflation does inevitably include significant contributions from isocurvature perturbation . the paper is organized as follows . in the second section , the theoretical setup is introduced . we review briefly the large volume approach to the moduli stabilization developed by quevedo and his collaborators in @xcite and establish our own two - field model . the third section is devoted to the investigation of possible inflationary dynamics in our model . we first present the equations of motion for the background fields and the linear perturbations , and then calculate the power spectra of these perturbations and their correlation by numerical integration . the obtained curvature power spectrum is nearly flat during most inflation and is characterized by a spectral index @xmath2 at the claimed hubble crossing . the final section is our conclusions . inflation in string theory is always associated with the resolvability of the moduli stabilization because the potential used to stabilize the heavy moduli might yield unacceptably large masses for the inflation drivers@xcite . in type iib superstring compactified on a calabi - yau orientifold , the closed string moduli consist of the complex structure moduli , dilaton field and the khler moduli . all complex structure moduli including the dilaton field could belong to the heavy moduli and be stabilized at a minimum of the effective potential if we introduce an imaginary self - dual 3-form flux into the orientifold construction@xcite . the stabilization of the khler moduli requires , according to kklt mechanism@xcite , introducing the nonperturbative contributions of the euclid d3-branes or some wrapped d7-branes to the superpotential , @xmath10 where @xmath11 with @xmath12 the @xmath13-th 4-cycle volume and @xmath14 the corresponding axions . the coefficients @xmath15 represent threshold corrections and are independent of the khler moduli . the khler potentials arising from type iib superstring are of no - scale or approximately no - scale@xcite , @xmath16 satisfying @xmath17 in the large volume limit @xmath18 , where @xmath19 , @xmath20 and @xmath21 . in ( [ eq : 2 ] ) the @xmath1-corrections have been included . combining with the superpotential given in eq.([eq : 1 ] ) , we see that the khler moduli do only appear exponentially in the f - term scalar potential . ] , @xmath22 \end{array}\ ] ] where @xmath23 . the uplifting correction to the scalar potential , which has several possible sources and is necessary to fine - tune the cosmological constant , depends on moduli only through the overall volume , @xmath24 where @xmath25 . for concreteness , we assume @xmath26 in the present paper . it is remarkable that , in the presence of several khler moduli , the variation of scalar potential along each @xmath27 direction is in general uncorrelated with its magnitude . besides , the potential is exponentially flat along some @xmath27 directions as long as these khler moduli are sufficient large . therefore , the large khler moduli have much chance to become the scalar fields to drive the early inflationary evolution of our universe . the calabi - yau orientifolds of swiss - cheese type have been shown to be very useful in string inflation engineering , whose volume can be formulated into a simplified form as follows@xcite , @xmath28\ ] ] here the volume of the @xmath13-th 4-cycle is denoted by @xmath29 , among which @xmath30 controls the overall volume and @xmath31 [ @xmath32 are blow - ups whose only non - vanishing triple intersections are with themselves . we stabilize the dilaton and complex structure moduli with fluxes , following the plausible kklt procedure@xcite . after that , the superpotential ( [ eq : 1 ] ) is reduced to be only khler moduli dependent , @xmath33 , where @xmath34 and for simplicity @xmath35 is assumed to be real . we establish our formalism in the large volume limit , where @xmath36 , @xmath37 , @xmath38 for @xmath39 but @xmath40 for @xmath41 and @xmath42 . because @xmath15 in superpotential ( [ eq : 1 ] ) are directly proportional to the squared masses of the corresponding khler moduli , @xmath27 are referred to be the heavy moduli when @xmath43 and light moduli when @xmath44 , respectively . in this limit , @xmath45 , the superpotential is approximately independent of @xmath46 which we will call the volume modulus , @xmath47 up to the magnitude of order @xmath48 , we can approximately write the scalar potential as @xmath49 , where the dominant part @xmath50 consists of the contributions of the volume modulus and the heavy moduli , and of the necessary uplifting potential , @xmath51 the contributions of the light khler moduli to the scalar potential do only appear in correction term @xmath52 , @xmath53 in eq.([eq : 8 ] ) , we have parameterized the uplifting potential as @xmath54 , with @xmath55 a positive parameter . there are terms not included in eqs.([eq : 8 ] ) and ( [ eq : 9 ] ) , which are subleading . in the large volume approach@xcite , the moduli stabilization problem of the khler moduli is solved in the following two - step procedure@xcite . first , we stabilize the axions @xmath14 ( @xmath56 ) to the potential minimum by setting @xmath57 . second , we can find an approximate minimum of the potential by letting @xmath50 be flat along the directions of @xmath58 and the heavy moduli @xmath12 ( @xmath59 ) in moduli space . the minimum of the scalar potential turns out approximately to be , @xmath60 + \frac{\gamma w_0 ^ 2}{{\mathcal v}_f^2}\ ] ] where @xmath61 that stands for the stabilized calabi - yau volume is the solution of the algebraic equation @xmath62\ ] ] with @xmath63 the heavy moduli will be stabilized at @xmath64 . phenomenologically , we expect that @xmath65 provides the dominant potential energy for the inflationary evolution of the survived light khler moduli . the cobe normalization of density perturbations at the hubble exit @xmath66 then demands@xmath67 at the hubble exit , where @xmath68 is the first slow - roll parameter . the range of @xmath68 at the horizon exit is @xmath69 for typical values of the microscopic parameters . thus the inflationary energy scale should be rather low in such models , @xmath70@xcite . this requirement can be easily satisfied by making some fine - tuning on the involved stringy parameters and , in fact , there exists a landscape in parameter space in favor of phenomenology and cosmology . one possibility that we will focus on in the next section is given by an orientifold model of @xmath71 , with geometrical parameters @xmath72 and @xmath73@xcite . the complex structure moduli including dilaton are supposed to be fixed by imaginary self - dual 3-form fluxes in such a manner that after these moduli are stabilized we have @xmath74 and consequently @xmath75 . the other microscopic parameters in the model are designated as , @xmath76 for such a model , numerical calculation tells us that @xmath77 , where @xmath78 . ] and @xmath79 . this setup is consistent with the upper bound @xmath80 from the present wmap dataset@xcite . ] . the volume modulus @xmath30 and heavy modulus @xmath81 are found to be frozen at @xmath82 and @xmath83 respectively , as expected . the large volume approach to heavy khler moduli stabilization naturally provides a platform for having a stringy inflation scenario , where the survived light khler moduli , say @xmath12 for @xmath84 ( @xmath85 ) play the roles of the multifield inflation drivers . the effective potential for these light moduli is @xmath86 and these scalar fields are assumed to be initially far from the minimum of potential @xmath87 ( please distinguish @xmath65 from the minimum of @xmath87 . the latter is expected to be zero ) . because in eq.([eq : 12 ] ) @xmath65 is one order of the fixed calabi - yau volume in the magnitude greater than the other scalar field dependent terms , the fixed volume @xmath61 and all of the stabilized heavy khler moduli as well as the associated axions will remain frozen during inflation . it is free of stabilization in the large volume approach . however , this is harmless . ] . these frozen heavy moduli will not create the harmful contributions to the masses of the light scalar fields . the form of potential ( [ eq : 12 ] ) implies that there is a stringy landscape to realize the cosmological inflation in iib flux compactification at the large volume limit . if we consider the type iib compactification on the calabi - yau orientifolds with @xmath88 , for example , we will get khler modulus inflation@xcite when the axion @xmath89 is stabilized at the potential minimum or roulette inflation@xcite when @xmath89 is dynamical . in this paper , we consider the iib compactification on a calabi - yau orientifold of @xmath90 , with almost all khler moduli ( including @xmath58 , @xmath30 and @xmath91 for @xmath92 ) have been stabilized . the only exception is for the two light moduli @xmath93 and @xmath94 which correspond to four scalar fields . the dynamics of this four - field system is governed by an effective potential @xmath95 recall that the effective superpotential for these fields is a sum of two exponential terms , the potential ( [ eq : 13 ] ) might be a large volume version of the better racetrack inflation model@xcite . the detailed investigation to this refined better racetrack model is scheduled to be published in the near future@xcite . in the present paper , we do what conlon and quevedo have done by fixing the axions to the potential minimum and ignoring the double exponentials , but regard both light khler moduli @xmath96 and @xmath97 as the relevant scalar fields ( here we take @xmath98 for simplicity ) . this will yield an assisted - like extension of the single field khler modulus inflation model . the potential energy for such a two - field system reads , @xmath99 the kinetic lagrangian is given by @xmath100 . explicitly , @xmath101 let @xmath102 with @xmath103 , we get , @xmath104 the potential ( [ eq : 14 ] ) can be recast as @xmath105 in terms of the newly defined fields . in eq.([eq : 17 ] ) we have defined @xmath106 , @xmath107 and @xmath108 for convenience . in this section , we intend to study the probable implications of the above two - field model on cosmology . the model emerges from the large volume approach to the moduli stabilization of type iib superstring flux compactification and is described by the effective action @xmath109 \label{eq : 18}\end{aligned}\ ] ] with @xmath110 given in eq.([eq : 17 ] ) . similar to the assisted inflation model@xcite , the potential @xmath110 consists of the sum of two exponentials of the scalar fields . the model can be thought of as a simplified version of the large volume better racetrack model in which two axionic fields have been stabilized at the potential minimum . in action ( [ eq : 18 ] ) , @xmath111 stands for the determinant of 4-dimensional metric tensor @xmath112 , whose ricci scalar curvature is denoted by @xmath113 . from the assigned stringy parameters for the model , the involved phenomenological parameters take values of @xmath114 and @xmath115 respectively . the potential has a minkowski minimum , @xmath116 , at @xmath117 . ] , however , it is very flat far away from this minimum . the crossing term in the kinetic lagrangian brings on much unnecessary inconvenience . to overcome it , we redefine the independent scalar fields by @xmath118 the action becomes @xmath119 \nonumber \\ & & \label{eq : 20}\end{aligned}\ ] ] where @xmath120 and @xmath121 . because in large volume limit the magnitudes of both @xmath122 and @xmath123 could be much smaller than _ one _ , the introduction of the field - dependent auxiliary quantity @xmath124 by its cosine value is reasonable . the appearance of @xmath124 in the kinetic lagrangian implies that we get a nontrivial diagonal metric in field space , which does not coincide with the known non - canonical two - field kinetic lagrangian studied in @xcite , and is expected to bring some new features in cosmological application . in terms of newly defined scalars , the minkowski minimum of the potential ( [ eq : 21 ] ) occurs at @xmath125 and @xmath126 . departure from this minimum is a plateau mainly along the @xmath122-direction which might be adequate for inflation . we begin with the equations of motion of the homogeneous background fields . consider a spatially flat robertson - walker spacetime @xmath127 here @xmath128 is the cosmic time . it is much convenient to formulate the equations of motion of the scalar fields in terms of the efold time @xmath129 , by which the equations of motion of the scalar fields are decoupled from the metric evolution . for the sake of convenience , we define a homogeneous inflaton field @xmath130 through its velocity , @xmath131 in eq.([eq : 23 ] ) and hereinafter , a dot stands for a derivative with respect to the efold time @xmath132 . the equations of motion of the scale factor in metric ( [ eq : 22 ] ) and the homogeneous background scalar fields are found to be , @xmath133 where @xmath87 is the abbreviation of the potential @xmath134 , @xmath135 is the hubble parameter but @xmath136 . inflation occurs for @xmath137 . hence , having an inflation driven by the above two scalar fields requires @xmath138 @xmath139 is the so - called first slow - roll parameter and @xmath140 . ] . is there an inflationary epoch with @xmath141 for our two - field model ? to have a definite answer to this question , we have to numerically solve eqs.([eq : 24]-[eq : 27 ] ) under appropriate initial conditions . in fact , it is sufficient to integrate eqs.([eq : 26 ] ) and ( [ eq : 27 ] ) only , since these scalar field equations are decoupled from the metric evolution . from the cauchy theorem , the solution to eqs.([eq : 26 ] ) and ( [ eq : 27 ] ) is unique provided the initial fields and initial field velocities are given at some initial instant @xmath142 . however , just as pointed out by ringeval@xcite , the attractor behavior induced by the friction terms erase any effect associated with the initial field velocities after a few efolds . the integration of eqs.([eq : 26 ] ) and ( [ eq : 27 ] ) depends essentially upon the initial field values only . the attractor behavior does also ensure the stability of forward numerical integration schemes , so we use a runge - kutta integration method of order four . numerically , we take @xmath143 ) below for explanation . ] and @xmath144 . it follows from eq.([eq : 19 ] ) that , if @xmath145 vanished , @xmath146 , the evolutions of @xmath147 and @xmath148 would exactly be the same , our multifield model would effectively reduce into a single field model . to have a small but significant deviation from such an indifferent situation , we take @xmath149 . such a choice for initial fields ensures them far away from their possible values at the minkowski minimum , and correspondingly the light khler moduli are initially set to be @xmath150 and @xmath151 , respectively . the initial field velocities are chosen on the attractor by setting @xmath152 . the inflationary epoch starts at @xmath153 where we put the initial conditions @xmath154 and @xmath155 . in the first @xmath156 efolds the trajectory is approximately along the @xmath157-direction ( red curve ) . when @xmath158 , the fields @xmath159 begin to lose their synchrony in evolution . a steep turn in field space takes place roughly at @xmath160 where @xmath161 , @xmath162 and after that @xmath163 does no longer evolve but @xmath164 continues to decrease . during the last efold , @xmath165 , the trajectory is along the @xmath166-direction ( magenta curve ) . the inflation approaches to its end at @xmath167 , where @xmath168 , @xmath169 and @xmath170.,title="fig : " ] . the inflationary epoch starts at @xmath153 where we put the initial conditions @xmath154 and @xmath155 . in the first @xmath156 efolds the trajectory is approximately along the @xmath157-direction ( red curve ) . when @xmath158 , the fields @xmath159 begin to lose their synchrony in evolution . a steep turn in field space takes place roughly at @xmath160 where @xmath161 , @xmath162 and after that @xmath163 does no longer evolve but @xmath164 continues to decrease . during the last efold , @xmath165 , the trajectory is along the @xmath166-direction ( magenta curve ) . the inflation approaches to its end at @xmath167 , where @xmath168 , @xmath169 and @xmath170.,title="fig : " ] figure [ trajectory ] gives our numerical solution to the classical trajectory of the scalar fields for @xmath171 . during most of the efolds , @xmath172 , the scalars roll very slowly and the trajectory is almost in the @xmath173-direction . being a two - field model means that the trajectory is not a straight line and in fact a sharp turn on trajectory occurs roughly at @xmath160 . within the last efold time interval the trajectory becomes another straight line along the @xmath166-direction . plugging this solution for @xmath174 and @xmath175 into eqs.([eq : 24 ] ) and ( [ eq : 25 ] ) determines the evolution of hubble parameter and the first slow - roll parameter @xmath139 . our choice of the initial conditions ensures both @xmath139 and @xmath176 much smaller than _ one _ for most of the efolds . in particular , @xmath177 and @xmath178 at the hubble exit ( @xmath179 ) . there is indeed an inflationary epoch in our model during which the hubble parameter hardly changes . the potential @xmath87 is very flat along the classical trajectory and , just as in the case of single field case@xcite , it is almost a constant , @xmath180 , for most of inflation . only within the final fractions of the last efold does a steep decay of potential take place . when @xmath132 impends over @xmath181 , the potential sharply drops off from the preceding constant to a metastable minimum with @xmath182 , where @xmath183 and the inflation is close to its end . during the efold time interval @xmath171 for our two - field model . @xmath139 is much smaller than _ one _ for most of the efolds , and particularly @xmath184 at @xmath185 , implying that the potential is almost flat during the epoch . @xmath139 increases drastically during the last several efolds . when @xmath186 , @xmath187 , the inflation tends to end . ] the apodictic deviation of trajectory from an entire straight line shows that what we consider is a genuine multifield model . provided that the isocurvature perturbation decays fast enough on the super - hubble scales , it will not influence the super - hubble curvature perturbation heavily even if the trajectory in field space deviates deadly from the straight - line one of a single field model . the steep decay of the isocurvature perturbations takes place in many supergravity or string theory inspired multifield models , and in particular in the string theory inspired roulette model@xcite . the inflation in these models is effectively driven by a single scalar field where one can use the single field approximation to account for the super - horizon power spectrum of the curvature perturbation . however , the same is not true for the present situation . in our two - field model , the decay of the isocurvature perturbation on super - hubble scales is not fast and the spectrum of the curvature perturbation in the vicinity of the hubble crossing is remarkably deviated by that at the end of inflation , where the correlation between the curvature and isocurvature modes becomes sufficiently strong so that the final curvature perturbation is heavily sourced by the isocurvature perturbation . we are going to confirm the above conclusion for the two - field model in consideration through numerical calculations of the power spectra of the linear perturbations and their correlation . due to the fact that at the hubble - exit @xmath188 , there is no important tensor fluctuations in our model . this might be a common feature of the stringy inflation models where the inflation is driven by some closed string moduli@xcite . so we consider only the scalar perturbations . because the matter is composed of two scalar fields , the stress tensor is diagonal and the perturbed metric is of the form @xmath189dt^2 + a(t)^2 \left[1 -2 \psi(t,{\bf x})\right]d{\bf x}^2\ ] ] in the longitudinal gauge . the scalar fields are decomposed into their homogeneous backgrounds plus the anisotropic perturbations : @xmath190 to facilitate solving the evolution equations of these cosmological perturbations , we can alternatively decompose them into the instantaneous curvature and isocurvature components , relying on the fact that the isocurvature modes do only source the curvature perturbations approximately@xcite . the curvature and isocurvature perturbations are parallel with and orthogonal to the trajectory of the homogeneous inflaton field @xmath130 , respectively . to define them we first introduce a time dependent angle @xmath191 , @xmath192 with which we can recast the background equations ( [ eq : 26 ] ) and ( [ eq : 27 ] ) as @xmath193 the curvature perturbation @xmath194 and isocurvature perturbation @xmath195 are defined through a linear transformation in field space @xmath196 = \sqrt2 \left [ \begin{array}{rr } \cos \alpha \cos \theta & \sin \alpha \sin \theta \\ -\cos \alpha \sin \theta & \sin \alpha \cos \theta \end{array } \right ] \left [ \begin{array}{r } \delta \varphi(t,{\bf x } ) \\ \delta \chi(t,{\bf x } ) \end{array } \right]\ ] ] from eq.([eq : 35 ] ) we have @xmath197 . the isocurvature perturbations turn out to be the entropy perturbations . to study the generation of perturbations from the vacuum fluctuations , we have to solve the closed set of eqs.([eq : 37 ] ) and ( [ eq : 38 ] ) under appropriate initial conditions . though the curvature and isocurvature fluctuations are finally coupled to each other beyond the hubble crossing , they might be statistically independent deeply inside the hubble radius . the initial efold time @xmath209 at which the perturbations are thought of as mutually independent must be much less than the hubble crossing instant @xmath210 for fourier mode perturbations of wave number @xmath204 , @xmath211 . the value of @xmath210 depends on the efold number during which the universe reheated before the starting of the radiation era@xcite and it is known@xcite that typically @xmath212 for @xmath213 . without knowledge of details of the reheating mechanism we can not be more precise to say what @xmath210 should be . however , if @xmath210 is known somehow , the efolding number @xmath214 of inflation after horizon crossing can be estimated from the assumption that the reheat temperature is of the same order as but slightly lower than the energy scale of inflation , @xmath215 gev , through the formula@xcite , @xmath216 we will simply set @xmath217 . then @xmath218 , compatible with the constraint from cosmological observation . the pivot wave number of the fourier mode perturbation is taken as @xmath219 for which the initial efold time @xmath209 can be defined by a cutoff equation@xcite @xmath220 the constant @xmath221 should be sufficient large in order that the probable interferences between the initial curvature and isocurvature modes remain negligible@xcite . we take @xmath222 for concreteness , which leads to @xmath223 . to take into account the statistical independence of the initial perturbations in our numerical procedure , we integrate eqs.([eq : 37 ] ) and ( [ eq : 38 ] ) twice : first with the initial conditions , @xmath224 and second with the initial conditions , @xmath225 with @xmath226 . the curvature and isocurvature perturbations are customarily described by @xmath227 and @xmath228 , for which we get @xmath229 and @xmath230 ( @xmath231 ) after finishing two individual integrations of eqs.([eq : 37 ] ) and ( [ eq : 38 ] ) . @xmath232 ( @xmath233 ) can be thought of as the curvature ( isocurvature ) perturbation without taking into account the coupling to the isocurvature ( curvature ) perturbation , and @xmath234 ( @xmath235 ) does just come from such a coupling . the final power spectra and their correlation are calculated as follows@xcite : @xmath236 in fact , the correlation between the curvature and isocurvature perturbations can be simply described by the so - called the relative correlation coefficient @xmath237 . the value of @xmath238 lies between @xmath239 and @xmath240 , which measures to what extent the final curvature perturbation results from the interactions with the isocurvature perturbation . . ] in the present model . it vanishes initially , as expected . at @xmath241 and @xmath242 , @xmath243 and @xmath244 , respectively . the coefficient increases monotonously on super - hubble scales . when inflation goes close to its end , @xmath167 , @xmath245 . ] our result of numerical integration for linear perturbations is displayed in figure [ spectracorrelation ] , where the power spectra of curvature and isocurvature perturbations as well as the correlation between them are plotted as functions of the number @xmath132 of efolds . on super - hubble scales the relative correlation coefficient continues to increase , which is displayed in figure [ correlation ] . the spectra drop off sharply on subhorizon scales until the supposed hubble exit for the fourier mode perturbation is achieved . on superhorizon scales , however , the spectra become sufficiently flat for @xmath246 , with @xmath247 and correlator @xmath248 increases steadily from @xmath249 to @xmath250 ( @xmath251 ) . during the period of @xmath252 , though @xmath253 increases at first but then drops off steeply , @xmath238 increases monotonously . for @xmath158 , the spectrum of curvature perturbation begins to increase while the spectrum of isocurvature begins to decrease once more . the persistent increase of the curvature perturbation spectrum for efold time interval @xmath254 reflects a fact that the correlation between the curvature and isocurvature perturbations during this time interval has become sufficiently strong that it can no longer be neglected . the decay of isocurvature perturbation spectrum accelerates in the final stage of inflation , which becomes unbelievable steep within the last efold and results in an unbelievable steep decay of correlator @xmath253 . for @xmath255 , in particular , both @xmath253 and @xmath256 become negligible ] to measure the relative contribution of the isocurvature fluctuations , @xmath257 . hence the constraint on isocurvature perturbations from observations@xcite is trivially matched and there is actually no observable isocurvature perturbation spectrum after inflation in the present two - field model . ] , and @xmath258 stops varying . therefore , in the present two - field model , the power spectrum of curvature perturbation on superhorizon scales is changeable with respect to time . this is in contrast with the single field inflation case where the curvature power spectrum remains approximately a constant after hubble crossing . figure [ curvaturespectrum ] gives the details of our numerical result for power spectrum of the curvature perturbation , where the three curves respectively stand for the complete curvature spectrum @xmath259 and its two terms @xmath260 and @xmath261 . . red curve describes the evolution of the complete curvature spectrum . pink and magenta curves stand for the partial curvature spectra from fluctuations along the inflationary trajectory and from the interactions with the isocurvature modes , respectively . the curvature spectrum at the end of inflation is @xmath262 , which is different from the curvature spectrum @xmath263 at hubble - exit . ] we see that for @xmath264 on superhorizon scales the spectrum of curvature perturbation originates almost exclusively from the fluctuations of the initial curvature perturbation along the inflationary trajectory . while for @xmath158 , the curvature - isocurvature correlation becomes important , the spectrum at the final stage of inflation contains considerable contributions from the interactions with the isocurvature modes . as a result , the curvature perturbation spectrum after inflation is slightly higher than the curvature perturbation spectrum at hubble crossing . the obtained power spectrum of the curvature perturbation in the present two - field model is in good agreement with the cobe normalization of power spectrum@xcite @xmath265 for @xmath264 . @xmath266 is an instant approximately 55 efoldings before the end of inflation , it is near the cobe normalization point . so @xmath267 is a reasonable efold time corresponding to hubble crossing . the scalar spectral index of the curvature power spectrum @xmath268 on superhorizon scales is also time - dependent , which has been calculated numerically with partial results given in figure [ index ] . at the claimed hubble crossing , @xmath269 , which is compatible with the best observational constraint available at present@xcite , @xmath270 . of the curvature power spectrum in the vicinity of hubble exit . the instant for cobe - like normalization corresponds roughly to @xmath185 , where @xmath2 . however , the index running is sufficiently small so that for @xmath271 , almost all values of @xmath272 are compatible with the observational constraint . ] it follows from the above numerical investigation that , in the two - field model under consideration , strong interactions exist between the curvature and isocurvature perturbations during the final stage of inflation . because the relative correlation coefficient increases steadily from the assigned tiny value deep inside the hubble radius to values very close to _ one _ at the end of inflation , a great deal curvature perturbation after inflation originates from interactions between the curvature and isocurvature perturbations on super - hubble scales , not only from the quantum fluctuations of the initial curvature perturbation along the classical trajectory . at this point , our model is somewhat similar to the double inflation with non - canonical kinetic terms and roulette inflation studied in @xcite . what distinguishes our model from the double inflation with non - canonical kinetic terms and roulette inflation is that in the former the power spectrum of isocurvature perturbation remains almost a constant during the most of inflationary epoch while in the latter it decays rapidly after the hubble radius crossing . this implies that in our model the isocurvature perturbation continues to interact with the curvature perturbation on superhorizon scales so that there is no an effective single field treatment available for it@xcite . we have established a multifield inflationary model on the large volume flux compactification scheme in type iib superstring orientifolds of @xmath273 . the khler moduli are categorized into volume modulus , heavy moduli and light moduli . almost all of closed string moduli emerging from the flux compactification are frozen at the potential minimum in the spirit of kklt mechanism in the large volume limit . however , this is not the case for light khler moduli . the light khler moduli have very small masses , they are not fixed by either the 3-form fluxes or nonperturbative effects in the effective superpotential , and could be the driving force for the potential inflationary evolution of the universe in its early history . to have a multifield inflation model , the superpotential is expected to contain several exponent terms for the light khler moduli . hence we have considered the orientifolds of @xmath274 and supposed that in our constructions the number of light khler moduli is equal to or greater than two . in some sense , in this paper we have proposed a plausible generalization of the better racetrack model@xcite in the large volume approach@xcite . the quantitative analysis of inflationary property in the resulting multifield inflationary model has been done in a simplified two - field model where there are only two light khler moduli with the axionic components being stabilized at the potential minimum also . this assisted - like model is an extension of the khler moduli inflation model@xcite to two - field inflation , which distinguishes itself by its kinetic lagrangian that is neither of canonical nor non - standard type studied in @xcite . our investigation consists of two steps . first , by some inevitable fine tuning in the initial conditions of the scalar fields , we integrate the background equations numerically and obtain the inflationary trajectory of the scalar fields . as a remarkable characteristic of the multifield model , the trajectory in field space in our model are strongly bent roughly 50 efolds after the hubble crossing . the first slow - roll parameter is numerically calculated which turns out to almost vanish for the first 60 efolds , implying that the scalar potential is very flat along the trajectory . second , we derive the evolution equations of the linear scalar perturbations . these equations are numerically integrated on which we have calculated the curvature , isocurvature spectra , and the correlation between them . our numerical estimation for the power spectrum of the curvature perturbation and the corresponding spectral index is in good agreement with the cobe normalization and the wmap observation dataset @xcite . in our model , the correlation between the curvature and isocurvature perturbations is gradually strong on super - hubble scales , so that the curvature spectrum approximately thirty efolds after the hubble exit is remarkably different from the curvature perturbation spectrum at the hubble exit , and there might be significant non - gaussianity in bispectrum and trispectrum of the primordial perturbations . the investigation of the deviations from gaussianity in power spectra in our two - field inflation model is in progress . we would like to thank m.li , j.x.lu and y.wang for stimulating discussions . this work was supported in part by cnsf-10375052 and the startup foundation of university of science and technology of china and the project of knowledge innovation program ( pkip ) of chinese academy of sciences . u. seljak and et al . , `` cosmological parameter analysis including sdss ly - alpha forest and galaxy bias : constraints on the primordial spectrum of fluctuations , neutrino mass , and dark energy , '' _ phys . rev . d _ * 71 * ( 2005 ) 103515 .

in this paper we present a two - field inflation model , which distinguishes itself with a non - canonical kinetic lagrangian and comes from the large volume approach to the moduli stabilization in flux compactification of type iib superstring on a calabi - yau orientifold of @xmath0 . the khler moduli are classified as volume modulus , heavy moduli and two light moduli . the axion - dilaton , complex structure moduli and all heavy khler moduli including the volume modulus are frozen by nonperturbatively corrected flux superpotential and the @xmath1-corrected khler potential in the large volume limit . the minimum of the scalar potential at which the heavy moduli are stabilized provides the dominant potential energy for the survived light khler moduli . we consider a simplified case where the axionic components in the light khler moduli are further stabilized at the potential minimum and only the geometrical components are taken as the scalar fields to drive an assisted - like inflation . for a certain range of moduli stabilization parameters and inflation initial conditions , we obtain a nearly flat power spectrum of the curvature perturbation , with @xmath2 at hubble - exit , and an inflationary energy scale of @xmath3 gev . in our model , significant correlation exists between the curvature and isocurvature perturbations on super - hubble scales so that at the end of inflation a great deal of the curvature power spectrum originates from this correlation .

Following an attack this morning on a bus driving children in Dahyan Market, northern Sa’ada, @ICRC_yemen- supported hospital has received dozens of dead and wounded. Under international humanitarian law, civilians must be protected during conflict.pic.twitter.com/x39NVB8G4p ||||| SANAA, Yemen (AP) — An airstrike by the Saudi-led coalition fighting Shiite rebels hit a bus in a market in northern Yemen on Thursday, killing at least 43 people, including children, and wounding as many as 63, Yemen's rebel-run Health Ministry said. The Saudi-led coalition, meanwhile, said it targeted the rebels, known as Houthis, who had fired a missile at the kingdom's south the previous day, killing one person. Yemen's rebel-run Al Masirah TV aired dramatic images of wounded children, their clothes and schoolbags covered with blood as they lay on hospital stretchers. The attack took place in the Dahyan market in Saada province, a Houthi stronghold. The province lies along the border with Saudi Arabia. The bus was ferrying local civilians, including many children, according to Yemeni tribal leaders who spoke on condition of anonymity for fear of reprisals. The elders said earlier the airstrike killed at least 20 people and wounded as many as 35. There was no breakdown in the casualties and it was not immediately clear how many of the victims were on the bus itself and how many were pedestrians in the immediate area around it. It was also unclear if there were other airstrikes in the area. Col. Turki al-Malki, a spokesman for the Saudi-led coalition, said the attack in Saada targeted the rebels who had fired a missile at the kingdom's south, killing one person and wounding 11 others. The coalition said Wednesday's projectile, fired toward the southwestern Saudi city of Jizan, was intercepted and destroyed but its fragments caused the casualties. The statement, carried by the official Saudi Press Agency, also said the missile was launched "deliberately to target residential and populated areas." Al-Malki insisted Thursday's attack carried out in Saada is a "legitimate military action" and is "in accordance with international humanitarian law and customs." He also accused the Houthis of recruiting children and using them in the battlefields to cover for their actions. Saudi Arabia backs Yemen's internationally recognized government and has been at war with the Houthis since March 2015. The rebels control much of northern Yemen, including the capital, Sanaa. The International Committee of the Red Cross said on Twitter that an ICRC supported hospital received dozens of dead and wounded following the attack that hit the bus with children. "Scores killed, even more injured, most under the age of ten," the head of the ICRC in Yemen, Johannes Bruwer, said on his Twitter account, adding that the ICRC in Yemen is "sending additional supplies to hospitals to cope with the influx." Later on Thursday, airstrikes hit the Yemeni capital, Sanaa, and sounds of the blasts reverberated across the city's southern and western neighborhoods. It was not immediately clear if there were any casualties in those strikes. Yemen's stalemated, three-year war has killed over 10,000 people, badly damaged Yemen's infrastructure and crippled its health system. The coalition faces widespread international criticism for its airstrikes in Yemen that kill civilians. Impoverished Yemen, on the southern tip of the Arabian Peninsula, is now in the world's worst humanitarian crisis, with more than 22.2 million people in need of assistance. Last week, Yemeni medical officials said the coalition conducted airstrikes in the rebel-held port city of Hodeida, killing at least 28 people and wounding 70. But the coalition denied carrying out any attacks in the city, saying it follows a "strict and transparent approach based on the rules international law." The fight for the port of Hodeida, a key lifeline for supplies and aid for Yemen's population on the brink of starvation, has become the latest battleground in the devastating war. The Iran-aligned Houthis regularly fire into Saudi Arabia and have targeted its capital, Riyadh, with ballistic missiles. They say their missile attacks on the kingdom are in retaliation for air raids on Yemen by the Western-backed coalition. The U.N. special envoy for Yemen, Martin Griffiths, has been pushing to bring the warring parties to restart peace talks. He recently announced plans to invite Yemen's warring parties to Geneva on Sept. 6 to hold the first round of consultations. ___ Associated Press writer Menna Zaki in Cairo contributed to this report.

– An airstrike hit a bus in a market in northern Yemen on Thursday, killing at least 43 people, including children, and wounding as many as 63, according to Yemen's rebel-run Health Ministry. The airstrike came from the Saudi-led coalition fighting Shiite Houthi rebels in the country, and the coalition said it was in retaliation for a missile fired at the kingdom the previous day. Yemen's rebel-run Al Masirah TV aired dramatic images of wounded children, their clothes and schoolbags covered with blood as they lay on hospital stretchers, per the AP. The attack took place in the Dahyan market in Saada province, a Houthi stronghold that lies along the border with Saudi Arabia. The bus was ferrying local civilians, including many children, according to Yemeni tribal leaders. The International Committee of the Red Cross said an ICRC-supported hospital received dozens of dead and wounded following the attack. "Scores killed, even more injured, most under the age of ten," adds the head of the ICRC in Yemen. Meanwhile, a spokesman for the Saudi-led coalition said the attack targeted rebels who had fired a missile at the kingdom's south, killing one person and wounding 11 others. The coalition said Wednesday's projectile, fired toward the southwestern Saudi city of Jizan, was intercepted and destroyed but its fragments caused the casualties. The spokesman insisted Thursday's attack was a "legitimate military action." Saudi Arabia backs Yemen's internationally recognized government and has been at war with the Houthis since March 2015. The rebels control much of northern Yemen, including the capital, Sanaa.

SECTION 1. SHORT TITLE; AMENDMENT OF 1986 CODE. (a) Short Title.--This Act may be cited as the ``Coverdell Education Savings Accounts Act of 2001''. (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. MODIFICATIONS TO EDUCATION INDIVIDUAL RETIREMENT ACCOUNTS. (a) Tax-Free Expenditures for Elementary and Secondary School Expenses.-- (1) In general.--Section 530(b)(2) (defining qualified higher education expenses) is amended to read as follows: ``(2) Qualified education expenses.-- ``(A) In general.--The term `qualified education expenses' means-- ``(i) qualified higher education expenses (as defined in section 529(e)(3)), and ``(ii) qualified elementary and secondary education expenses (as defined in paragraph (4)). ``(B) Qualified state tuition programs.--Such term shall include any contribution to a qualified State tuition program (as defined in section 529(b)) on behalf of the designated beneficiary (as defined in section 529(e)(1)); but there shall be no increase in the investment in the contract for purposes of applying section 72 by reason of any portion of such contribution which is not includible in gross income by reason of subsection (d)(2).''. (2) Qualified elementary and secondary education expenses.--Section 530(b) (relating to definitions and special rules) is amended by adding at the end the following new paragraph: ``(4) Qualified elementary and secondary education expenses.-- ``(A) In general.--The term `qualified elementary and secondary education expenses' means-- ``(i) expenses for tuition, fees, academic tutoring, special needs services, books, supplies, computer equipment (including related software and services), and other equipment which are incurred in connection with the enrollment or attendance of the designated beneficiary of the trust as an elementary or secondary school student at a public, private, or religious school, and ``(ii) expenses for room and board, uniforms, transportation, and supplementary items and services (including extended day programs) which are required or provided by a public, private, or religious school in connection with such enrollment or attendance. ``(B) School.--The term `school' means any school which provides elementary education or secondary education (kindergarten through grade 12), as determined under State law.''. (3) Conforming amendments.--Section 530 is amended-- (A) by striking ``higher'' each place it appears in subsections (b)(1) and (d)(2), and (B) by striking ``higher'' in the heading for subsection (d)(2). (b) Maximum Annual Contributions.-- (1) In general.--Section 530(b)(1)(A)(iii) (defining education individual retirement account) is amended by striking ``$500'' and inserting ``the applicable dollar amount for the calendar year in which such taxable year begins''. (2) Applicable dollar amount.--Section 530(b) is amended by adding at the end the following new paragraph: ``(4) Applicable dollar amount.-- ``(A) In general.--For purposes of paragraph (1)(A)(iii), the applicable dollar amount is $2,000. ``(B) Inflation adjustment.-- ``(i) In general.--In the case of any taxable year beginning after 2002, the dollar amount referred to in subparagraph (A) shall be increased by an amount equal to-- ``(I) such dollar amount, multiplied by ``(II) the cost-of-living adjustment determined under section (1)(f)(3) for the calendar year in which the taxable year begins, by substituting `2001' for `1992'. ``(ii) Rounding.--If any amount as adjusted under clause (i) is not a multiple of $50, such amount shall be rounded to the nearest multiple of $50.''. (3) Conforming amendment.--Section 4973(e)(1)(A) is amended by striking ``$500'' and inserting ``the applicable dollar amount for the calendar year in which such taxable year begins''. (4) Elimination of the marriage penalty in the reduction in permitted contributions.--Section 530(c)(1) (relating to reduction in permitted contributions based on adjusted gross income) is amended-- (A) by striking ``$150,000'' in subparagraph (A)(ii) and inserting ``$190,000'', and (B) by striking ``$10,000'' in subparagraph (B) and inserting ``$30,000''. (c) Waiver of Age Limitations for Children With Special Needs.-- Section 530(b)(1) (defining education individual retirement account) is amended by adding at the end the following flush sentence: ``The age limitations in subparagraphs (A)(ii) and (E) and paragraphs (5) and (6) of subsection (d) shall not apply to any designated beneficiary with special needs (as determined under regulations prescribed by the Secretary).''. (d) Entities Permitted To Contribute to Accounts.--Section 530(c)(1) (relating to reduction in permitted contributions based on adjusted gross income) is amended by striking ``The maximum amount which a contributor'' and inserting ``In the case of a contributor who is an individual, the maximum amount the contributor''. (e) Time When Contributions Deemed Made.-- (1) In general.--Section 530(b) (relating to definitions and special rules), as amended by subsection (b)(2), is amended by adding at the end the following new paragraph: ``(5) Time when contributions deemed made.--An individual shall be deemed to have made a contribution to an education individual retirement account on the last day of the preceding taxable year if the contribution is made on account of such taxable year and is made not later than the time prescribed by law for filing the return for such taxable year (not including extensions thereof).''. (2) Extension of time to return excess contributions.-- Subparagraph (C) of section 530(d)(4) (relating to additional tax for distributions not used for educational expenses) is amended-- (A) by striking clause (i) and inserting the following new clause: ``(i) such distribution is made before the 1st day of the 6th month of the taxable year following the taxable year, and'', and (B) by striking ``due date of return'' in the heading and inserting ``certain date''. (f) Coordination With Hope and Lifetime Learning Credits and Qualified Tuition Programs.-- (1) In general.--Section 530(d)(2)(C) is amended to read as follows: ``(C) Coordination with hope and lifetime learning credits and qualified tuition programs.--For purposes of subparagraph (A). ``(i) Credit coordination.--The total amount of qualified higher education expenses with respect to an individual for the taxable year shall be reduced-- ``(I) as provided in section 25A(g)(2), and ``(II) by the amount of such expenses which were taken into account in determining the credit allowed to the taxpayer or any other person under section 25A. ``(ii) Coordination with qualified tuition programs.--If, with respect to an individual for any taxable year-- ``(I) the aggregate distributions during such year to which subparagraph (A) and section 529(c)(3)(B) apply, exceed ``(II) the total amount of qualified higher education expenses (after the application of clause (i)) for such year, the taxpayer shall allocate such expenses among such distributions for purposes of determining the amount of the exclusion under subparagraph (A) and section 529(c)(3)(B).''. (2) Conforming amendments.-- (A) Subsection (e) of section 25A is amended to read as follows: ``(e) Election Not To Have Section Apply.--A taxpayer may elect not to have this section apply with respect to the qualified tuition and related expenses of an individual for any taxable year.''. (B) Section 135(d)(2)(A) is amended by striking ``allowable'' and inserting ``allowed''. (C) Section 530(d)(2)(D) is amended-- (i) by striking ``or credit'', and (ii) by striking ``credit or'' in the heading. (D) Section 4973(e)(1) is amended by adding ``and'' at the end of subparagraph (A), by striking subparagraph (B), and by redesignating subparagraph (C) as subparagraph (B). (g) Renaming Education Individual Retirement Accounts as Coverdell Education Savings Accounts.-- (1) In general.-- (A) Section 530 (as amended by the preceding provisions of this section) is amended by striking ``an education individual retirement account'' each place it appears and inserting ``a Coverdell education savings account''. (B) The heading for paragraph (1) of section 530(b) is amended by striking ``Education individual retirement account'' and inserting ``Coverdell education savings account''. (C) The heading for section 530 is amended to read as follows: ``SEC. 530. COVERDELL EDUCATION SAVINGS ACCOUNTS.''. (D) The item in the table of contents for part VII of subchapter F of chapter 1 relating to section 530 is amended to read as follows: ``Sec. 530. Coverdell education savings accounts.''. (2) Conforming amendments.-- (A) The following provisions are each amended by striking ``an education individual retirement'' each place it appears and inserting ``a Coverdell education savings'': (i) Section 25A(e)(2). (ii) Section 72(e)(9). (iii) Section 135(c)(2)(C). (iv) Section 4973(a). (v) Subsections (c) and (e) of section 4975. (B) The following provisions are each amended by striking ``education individual retirement'' each place it appears and inserting ``Coverdell education savings'': (i) Section 26(b)(2)(E). (ii) Section 4973(e). (iii) Section 6693(a)(2)(D). (C) The headings for each of the following provisions are amended by striking ``education individual retirement accounts'' each place it appears and inserting ``Coverdell education savings accounts''. (i) Section 72(e)(9). (ii) Section 135(c)(2)(C). (iii) Section 4973(e). (iv) Section 4975(c)(5). (h) Effective Dates.-- (1) In general.--Except as provided in paragraph (2), the amendments made by this section shall apply to taxable years beginning after December 31, 2001. (2) Subsection (g).--The amendments made by subsection (g) shall take effect on the date of the enactment of this Act. SEC. 3. EXCLUSION FROM INCOME OF CERTAIN AMOUNTS CONTRIBUTED TO COVERDELL EDUCATION SAVINGS ACCOUNTS. (a) In General.--Part III of subchapter B or chapter 1 of the Internal Revenue Code of 1986 (relating to items specifically excluded from gross income) is amended by redesignating section 139 as section 140 and by adding at the end the following: ``SEC. 139. COVERDELL EDUCATION SAVINGS ACCOUNTS. ``(a) Exclusion From Gross Income.--Gross income of an employee shall not include-- ``(1) amounts paid or incurred by the employer for a qualified Coverdell education savings account contribution on behalf of the employee or a member of the employee's family, and ``(2) any distribution from a Coverdell education savings account of such contribution. ``(b) Qualified Coverdell Education Savings Account Contribution.-- For purposes of this section-- ``(1) In general.--The term `qualified Coverdell education savings account contribution' means an amount contributed, directly or indirectly, as part of an education savings program by an employer to a Coverdell education savings account established and maintained for the benefit of the employee or a member of the employee's family. ``(2) Education savings program.--For purposes of paragraph (1), an education savings program is a separate written plan of an employer for the exclusive benefit of such employer's employees-- ``(A) under which the employer makes contributions described in paragraph (1), and ``(B) which meets requirements similar to the requirements of paragraphs (2), (3), (5), and (6) of section 127(b).''. (b) Conforming Amendment.--The table of sections for part III of subchapter B or chapter 1 of the Internal Revenue Code of 1986 is amended by striking the item relating to section 139 and by inserting the following: ``Sec. 139. Coverdell education savings accounts. ``Sec. 140. Cross references to other Acts.''. (c) Effective Date.--The amendments made by this section shall apply to contributions made in taxable years beginning after December 31, 2001.

Coverdell Education Savings Accounts Act of 2001 - Amends the Internal Revenue Code, with respect to education individual retirement accounts (IRAs), to: (1) permit distributions for qualified elementary and secondary education expenses; (2) increase annual contribution limits from $500 to $2,000, with annual inflation adjustments as of tax year 2003; (3) waive the beneficiary age limitation (18) for contributions on behalf of special needs beneficiaries; (4) permit corporations to contribute to education IRAs; (5) permit annual contributions to be made until the filing date (not including extensions) for a tax year; (6) extend the time for return of excess contributions; and (7) provide for coordination with Hope and lifetime learning credit and qualified tuition program provisions.Renames such educational IRAs as Coverdell education savings accounts.Excludes from gross income: (1) employer contributions to such accounts on behalf of an employee or employee family member; and (2) account distributions.

TITLE I--LEWIS AND CLARK NATIONAL HISTORICAL PARK DESIGNATION ACT SEC. 101. SHORT TITLE. This title may be cited as the ``Lewis and Clark National Historical Park Designation Act''. SEC. 102. DEFINITIONS. As used in this title: (1) Park.--The term ``park'' means the Lewis and Clark National Historical Park designated in section 103. (2) Secretary.--The term ``Secretary'' means the Secretary of the Interior. SEC. 103. LEWIS AND CLARK NATIONAL HISTORICAL PARK. (a) Designation.--In order to preserve for the benefit of the people of the United States the historic, cultural, scenic, and natural resources associated with the arrival of the Lewis and Clark Expedition in the lower Columbia River area, and for the purpose of commemorating the culmination and the winter encampment of the Lewis and Clark Expedition in the winter of 1805-1806 following its successful crossing of the North American Continent, there is designated as a unit of the National Park System the Lewis and Clark National Historical Park. (b) Boundaries.--The boundaries of the park are those generally depicted on the map entitled ``Lewis and Clark National Historical Park, Boundary Map'', numbered 405/80027, and dated December 2003, and which includes-- (1) lands located in Clatsop County, Oregon, which are associated with the winter encampment of the Lewis and Clark Expedition, known as Fort Clatsop and designated as the Fort Clatsop National Memorial by Public Law 85-435, including the site of the salt cairn (specifically, lot number 18, block 1, Cartwright Park Addition of Seaside, Oregon) used by that expedition and adjacent portions of the old trail which led overland from the fort to the coast; (2) lands identified as ``Fort Clatsop 2002 Addition Lands'' on the map referred to in this subsection; and (3) lands located along the lower Columbia River in the State of Washington associated with the arrival of the Lewis and Clark Expedition at the Pacific Ocean in 1805, which are identified as ``Station Camp'', ``Clark's Dismal Nitch'', and ``Cape Disappointment'' on the map referred to in this subsection. (c) Acquisition of Land.-- (1) Authorization.--The Secretary is authorized to acquire land, interests in land, and improvements therein within the boundaries of the park, as identified on the map referred to in subsection (b), by donation, purchase with donated or appropriated funds, exchange, transfer from any Federal agency, or by such other means as the Secretary deems to be in the public interest. (2) Consent of landowner required.--The lands authorized to be acquired under paragraph (1) (other than corporately owned timberlands within the area identified as ``Fort Clatsop 2002 Addition Lands'' on the map referred to in subsection (b)) may be acquired only with the consent of the owner. (3) Acquisition of fort clatsop 2002 addition lands.--If the owner of corporately owned timberlands within the area identified as ``Fort Clatsop 2002 Addition Lands'' on the map referred to in subsection (b) agrees to enter into a sale of such lands as a result of actual condemnation proceedings or in lieu of condemnation proceedings, the Secretary shall enter into a memorandum of understanding with the owner regarding the manner in which such lands shall be managed after acquisition by the United States. (d) Cape Disappointment.-- (1) Transfer.--Subject to valid rights (including withdrawals), the Secretary shall transfer to the Director of the National Park Service management of any Federal land at Cape Disappointment, Washington, that is within the boundary of the park. (2) Withdrawn land.-- (A) Notice.--The head of any Federal agency that has administrative jurisdiction over withdrawn land at Cape Disappointment, Washington, within the boundary of the park shall notify the Secretary in writing if the head of the Federal agency does not need the withdrawn land. (B) Transfer.--On receipt of a notice under subparagraph (A), the withdrawn land shall be transferred to the administrative jurisdiction of the Secretary, to be administered as part of the park. (3) Memorial to thomas jefferson.--All withdrawals of the 20- acre parcel depicted as a ``Memorial to Thomas Jefferson'' on the map referred to in subsection (b) are revoked, and the Secretary shall establish a memorial to Thomas Jefferson on the parcel. (4) Management of cape disappointment state park land.--The Secretary may enter into an agreement with the State of Washington providing for the administration by the State of the land within the boundary of the park known as ``Cape Disappointment State Park''. (e) Map Availability.--The map referred to in subsection (b) shall be on file and available for public inspection in the appropriate offices of the National Park Service. SEC. 104. ADMINISTRATION. (a) In General.--The park shall be administered by the Secretary in accordance with this title and with laws generally applicable to units of the National Park System, including the Act of August 25, 1916 (39 Stat. 535; 16 U.S.C. 1 et seq.) and the Act of August 21, 1935 (49 Stat. 666; 16 U.S.C. 461 et seq.). (b) Management Plan.--Not later than 3 years after funds are made available for this purpose, the Secretary shall prepare an amendment to the General Management Plan for Fort Clatsop National Memorial to guide the management of the park. (c) Cooperative Management.--In order to facilitate the presentation of a comprehensive picture of the Lewis and Clark Expedition's experiences in the lower Columbia River area and to promote more efficient administration of the sites associated with those experiences, the Secretary may enter into cooperative management agreements with appropriate officials in the States of Washington and Oregon in accordance with the authority provided under section 3(l) of Public Law 91-383 (112 Stat. 3522; 16 U.S.C. 1a-2). SEC. 105. REPEAL OF SUPERSEDED LAW. (a) In General.--Public Law 85-435 (72 Stat. 153; 16 U.S.C. 450mm et seq.), regarding the establishment and administration of Fort Clatsop National Memorial, is repealed. (b) References.--Any reference in any law (other than this title), regulation, document, record, map or other paper of the United States to ``Fort Clatsop National Memorial'' shall be considered a reference to the ``Lewis and Clark National Historical Park''. SEC. 106. PRIVATE PROPERTY PROTECTION. (a) Access to Private Property.--Nothing in this title shall be construed to-- (1) require any private property owner to permit public access (including Federal, State, or local government access) to such private property; or (2) modify any provision of Federal, State, or local law with regard to public access to or use of private lands. (b) Liability.--Designation of the park shall not be considered to create any liability, or to have any effect on any liability under any other law, of any private property owner with respect to any persons injured on such private property. (c) Recognition of Authority to Control Land Use.--Nothing in this title shall be construed to modify any authority of Federal, State, or local governments to regulate the use of private land within the boundary of the park. SEC. 107. AUTHORIZATION OF APPROPRIATIONS. There are authorized to be appropriated such sums as may be necessary to carry out this title. TITLE II--LEWIS AND CLARK EASTERN LEGACY STUDY SEC. 201. DESIGNATION OF ADDITIONAL SITES FOR STUDY. (a) Study.-- (1) In general.--The Secretary of the Interior shall update, with an accompanying map, the 1958 Lewis and Clark National Historic Landmark theme study to determine the historical significance of the eastern sites of the Corps of Discovery expedition used by Meriwether Lewis and William Clark, whether independently or together, in the preparation phase starting at Monticello, Virginia, and traveling to Wood River, Illinois, and the return phase from Saint Louis, Missouri, to Washington, District of Columbia, including sites in Virginia, Washington, District of Columbia, Maryland, Delaware, Pennsylvania, West Virginia, Ohio, Kentucky, Tennessee, Indiana, and Illinois. (2) Focus of update; nomination and addition of properties.-- The focus of the study under paragraph (1) shall be on developing historic context information to assist in the evaluation and identification, including the use of plaques, of sites eligible for listing in the National Register of Historic Places or designation as a National Historic Landmark. (b) Report.--Not later than 1 year after funds are made available for the study under this section, the Secretary shall submit to the Committee on Resources in the House of Representatives and the Committee on Energy and Natural Resources in the Senate a report describing any findings, conclusions, and recommendations of the study. SEC. 202. AUTHORIZATION OF APPROPRIATIONS. There are authorized to be appropriated such sums as may be necessary to carry out this title. Speaker of the House of Representatives. Vice President of the United States and President of the Senate.

Title I: Lewis and Clark National Historical Park Designation Act - Lewis and Clark National Historical Park Designation Act - (Sec. 103) Designates the Lewis and Clark National Historical Park as a unit of the National Park System. Defines the boundaries of the park, located in the States of Oregon and Washington, according to a map entitled "Lewis and Clark National Historical Park, Boundary Map" (December 2003), which includes the Fort Clatsop National Memorial and other specified lands. Authorizes the Secretary of the Interior to acquire land, interests in land, and improvements therein within park boundaries. Directs that such land may be acquired only with the consent of the owner except with regard to specified corporately owned timberlands. Requires the Secretary, if the owner of specified corporately owned timberlands agrees to sell as a result of actual condemnation proceedings or in lieu of condemnation proceedings, to enter into a memorandum of understanding with the owner addressing post-acquisition management of those lands. Directs the Secretary to transfer, subject to valid rights (including withdrawals), to the Director of the National Park Service management of any Federal land at Cape Disappointment, Washington, that is within the boundary of the park. Revokes all withdrawals of a specified 20-acre parcel depicted as a "Memorial to Thomas Jefferson" and directs the Secretary to establish a memorial to Thomas Jefferson on the parcel. Authorizes the Secretary to enter into an agreement with the State of Washington providing for the administration by such State of the land within the boundary of the park known as Cape Disappointment State Park. (Sec. 104) Requires the Secretary to: (1) administer the park in accordance with this title and with laws generally applicable to the NPS; and (2) prepare an amendment to the general management plan for Fort Clatsop National Memorial to guide management of the Park. Authorizes the Secretary to enter into cooperative management agreements with appropriate officials in Oregon and Washington with respect to the conduct of living exhibits and interpretive demonstrations. (Sec. 105) Repeals specified law regarding the establishment and administration of Fort Clatsop National Memorial. (Sec. 106) Prohibits anything in this title from being construed to: (1) require any private property owner to permit public access (including government access) to such private property; or (2) modify any provision of law concerning public access to or use of private lands. States that designation of the Park shall not be considered to create any liability, or to have any effect on any liability under any other law, of any private property owner with respect to any persons injured on such private property. Prohibits anything in this title from being construed to modify any authority to regulate the use of private land within the Park's boundaries. (Sec. 107) Authorizes appropriations. Title II: Lewis and Clark Eastern Legacy Study - (Sec. 201) Directs the Secretary to update the 1958 Lewis and Clark National Historic Landmark theme study of the eastern sites of the Corps of Discovery expedition used by Lewis and Clark in the preparation phase starting at Monticello, Virginia, and traveling to Wood River, Illinois, and the return phase from Saint Louis, Missouri, to Washington, District of Columbia, including sites in Virginia, Washington, District of Columbia, Maryland, Delaware, Pennsylvania, West Virginia, Ohio, Kentucky, Indiana, and Illinois. Requires the study's focus to be on developing historic context information to assist in the evaluation and identification of sites eligible for listing in the National Register of Historic Places or designation as a National Historic Landmark. Requires the Secretary to report to Congress on any findings, conclusions, and recommendations. (Sec. 202) Authorizes appropriations.

the jovian trojan asteroids inhabit two large co - orbital swarms at the l4 and l5 lagrangian points of the sun - jupiter system . their unique location , in between the largely rocky asteroids of the main - belt and the icy kuiper belt objects beyond neptune , suggests that the trojans may preserve important distance- and temperature - dependent compositional trends . it has long been recognized that the trojans are observationally similar to the nuclei of comets , in terms of their slightly reddish colors @xcite and their low albedos @xcite . they are quite distinct from , for example , the s - type asteroids that dominate the inner regions of the main asteroid belt @xcite . on the other hand , while comet nuclei are known to be ice - rich , no water ice has ever been identified on a trojan asteroid despite the expenditure of considerable observational effort @xcite . water ice is expected to be an important constituent of bodies formed beyond the snow line , where water is thermodynamically stable in the solid phase . the absence of surface water ice may be due , as on the nuclei of comets , to the formation of a refractory surface mantle that is a by - product of past sublimation @xcite . if so , the surface properties of the trojans reveal the nature of the refractory components of these bodies , with ice perhaps remaining stable only at depths to which optical and infrared photons can not penetrate . the source regions from which the trojans were captured remain unknown . published hypotheses fall into two main categories : one suggests that trojans are planetesimals captured from the vicinity of the orbit of the giant planet @xcite , while the other suggests that the trojans might have formed in the kuiper belt at an early epoch , and then were scattered and captured into their current orbits @xcite . trojans accreted near jupiter s orbit ( 5 au and temperatures @xmath1100k to 150 k ) and in the much more distant kuiper belt ( 30 au and 50 k ) should differ compositionally . therefore , the chemical composition of the trojans should set important constraints on the plausible source regions of these objects . recently , the thermal emissivity spectra of three trojan asteroids , namely ( 624 ) hektor , ( 911 ) agamemnon and ( 1172 ) aneas , were reported by @xcite . these three trojan spectra , taken by the spitzer space telescope , show an almost identical emissivity maximum near 10-@xmath0 m with two weaker features near 20 @xmath0 m . these features are difficult to match with laboratory meteorite spectra or synthetic mineral spectra but closely resemble the 10 @xmath0 m and 20 @xmath0 m features found in the spectra of comets @xcite . the cometary emission features are attributed to the si - o vibrational modes in small silicate grains @xcite . silicate grains with radii larger than a few tens of microns do not exhibit 10 and 20 @xmath0 m spectral features but display black body - like spectra because large grains are optically thick at these wavelengths @xcite . the detection of the thermal emission features suggests a very porous distribution of small silicate grains on the surfaces of these trojans . this finding is consistent with previous studies @xcite , which demonstrated that synthetic models incorporating amorphous carbon and amorphous pyroxene can adequately reproduce the common red slopes of the trojan spectra in the near infrared ( nir ) . the porous distribution of small particles might have been caused by past or on - going cometary activity . however , the process is not understood in detail . howell ( 1995 ) performed visible and infrared spectrophotometry of 17 trojans and reported that nine out of seventeen trojans showed an absorption feature near 1.0 @xmath0 m , when the data from the eight - color asteroid surve @xcite were included . if real , this feature would be consistent with the diagnostic 1-@xmath0 m silicate band , which is attributed to fe@xmath2 crystal field transitions in iron - bearing silicates @xcite . the detection of the 1-@xmath0 m feature in the nir and the strong 10-@xmath0 m features in the mid - infrared ( mir ) suggest that the surfaces of trojan asteroids could be dominated by silicate - rich mantles . however , the detections by howell ( 1995 ) were based on multi - color photometry taken with single - element detectors and remain observationally unconfirmed . accordingly , the first objective of this paper is to verify the presence of the 1-@xmath0 m absorption feature at higher spectral resolution and signal - to - noise - ratios ( snrs ) . most , but not all , of the trojans with taxonomical classifications are p- or d - types based on their optical reflectance spectra . the latter are generally featureless with a moderate or very steep red spectral slope longward of 0.55 @xmath0 m @xcite . a common belief among planetary scientists is that trojans are exclusively red . but is this really true ? recently , several trojans were found to have neutral or grey colors in the optical @xcite . many of these grey trojans belong to one dynamical family , the eurybates family @xcite . members of this family were reported to have optical spectra with normalized spectral slopes , @xmath3 , of no more than a few percent per 1000 , which closely resemble the c - type asteroid spectra @xcite . given the dominating fraction of the p- and d - types among the trojan population , the rareness of the c - type - like grey trojans in itself is interesting . more importantly , @xcite reported that the red - sloped trojans generally show stronger thermal emission features than those that have neutral ( grey ) spectra . however , trojans that have been studied in the nir are mainly ( red sloped ) d - types and the nir properties of c - type trojans remain largely under - sampled . therefore , the second objective of this paper is to investigate surface properties of grey trojans via nir spectroscopy to improve our knowledge of these objects . we observed three eurybates family members in the nir , together with two non - family grey objects to investigate : a ) whether the eurybates family possesses any special traits , b ) whether grey objects with neutral optical spectra display any diagnostic features that are indicative of their mineralogy . the nir spectra were obtained using the nasa infrared telescope facility ( irtf ) 3-m telescope atop mauna kea , hawaii . a medium - resolution 0.8 - 5.5 @xmath0 m spectrograph ( spex ) was used , equipped with a raytheon 1024 @xmath41024 insb array having a spatial scale of 0.@xmath515 pixel@xmath6 @xcite . the low - resolution prism mode was used to cover an overall wavelength range from 0.8 @xmath0 m to 2.5 @xmath0 m for all of our observations . we used a 0.8@xmath7x15@xmath7 slit that provided an average spectral resolving power of @xmath1130 . to correct for strong telluric absorption features from atmospheric oxygen and water vapor , we used g2v stars that were close to the scientific target both in time and sky position as telluric calibration standard stars . the g2v stars generally have spectral slopes similar to the sun and they also served as solar analogs for computing relative reflectance spectra of the scientific targets . usually , two standard stars ( with airmasses different from the target and from each other by @xmath8 0.1 ) were observed before and after each scientific object to ensure good telluric calibration and to reduce systematic errors introduced into the reflectance spectra due to potentially imperfect solar analogs . during our observations , the slit was always oriented along the parallactic angle to minimize effects from differential atmospheric refraction . the spex data were reduced using the spextool reduction pipeline @xcite . all frames were flatfielded . bad pixels were identified and removed using flat field frames as well as a stored bad pixel mask . the first - order sky removal was achieved via subtracting image pairs with the object dithered along the slit by an offset of 7.@xmath55 . wavelength calibration was accomplished using argon lines from an internal calibration lamp . the reflectivity spectra , @xmath9 , were computed by dividing the calibrated trojan spectra by the spectra of nearby solar analogs . a journal of observations is provided in table 1 . we observed seven trojans that were previously reported to display a distinctive absorption feature near 1.0 @xmath0 m ( howell 1995 ) . our newly obtained nir spectra are illustrated in figure [ f1 ] . all seven trojans appear featureless in our data and have reddish spectral slopes from 0.8 to 2.5 @xmath0 m . detailed comparisons between our observations and the ones of howell ( 1995 ) are presented in figure [ f2 ] for ( 2223 ) sarpedon and ( 1172 ) aneas . the former has the strongest 1-@xmath0 m absorption band among all seven trojans in howell ( 1995 ) , while the latter was observed using nasa s spitzer space telescope and found to exhibit a significant 10-@xmath0 m emission feature . we normalized both our data and the photometric data from ( howell 1995 ) at 1.7 @xmath0 m . in figure [ f2 ] , the black and the orange solid lines represent the nir spectra of sarpedon and aneas that were taken on ut 2007 apr . 06 and 07 , respectively . the filled black squares are photometric measurements of these two objects taken from howell ( 1995 ) . the dashed lines are cubic spline fits to the photometric points . our spline fitting curves are similar to the original fits in howell ( 1995 ) . we found that our data are broadly consistent with howell s measurements in the wavelength range from 1.0 to 2.5 @xmath0 m , except for the deviation near 1.1 @xmath0 m , where howell s data show a strong absorption band while we did not see this feature in our data . to search for possible weak features , we examined the continuum - removed residual spectra , shown in figure [ f3 ] . as illustrated in figure [ f1 ] , the continua of several trojans in our sample are non - linear and show a turnover near 1.5 @xmath0 m . therefore , we split each spectrum into two parts then fit and subtract the continuum from each part separately . at short wavelengths ( 0.8 - 1.5 @xmath0 m ) , a linear regression model was used to fit the continua . at longer wavelengths ( 1.5 - 2.5 @xmath0 m ) , a second - order polynomial function was used . note that we excluded regions ( 1.35 -1.45 @xmath0 m , 1.8 -1.95 @xmath0 m ) that are contaminated by the telluric absorptions from continuum fitting . some small variations present near 0.9 , 1.4 , 2.0 and 2.1 @xmath0 m are caused by imperfect telluric calibration . based on the noise level in the spex data , we conclude that no absorption features deeper than 1% were present in the seven observed trojans . the data from howell ( 1995 ) were also used to estimate band depths and the results are compared in table [ abs_lim ] . given that our data were taken at far higher spectral resolution and signal - to - noise ratios , we conclude that the previously reported 1-@xmath0 m band is unlikely to be real . the possibility that we might have missed the 1-@xmath0 m feature because of azimuthal non - uniformities on the rotating trojans seems unlikely , both because we would have to be unlucky with all seven objects and because we observed each on two different nights . furthermore , observations of other asteroids generally show that azimuthal spectral variations are either small or undetectable . as shown in figure [ f1 ] , the spectrum of ( 1208 ) troilus is distinct from the other six trojans . firstly , troilus exhibits a nearly flat near - infrared spectrum with a spectral slope @xmath3 = @xmath10 1.2%/10@xmath11 ( obtained via fitting a linear function to the entire spectrum from 0.8 to 2.5 @xmath0 m ) . in contrast , the other trojans have steeper slopes ( @xmath12 3.0%/10@xmath11 ) in the same spectral region . secondly , the spectrum of troilus has a nearly unchanging slope with wavelength ( @xmath13 = @xmath14 0 ) , whereas the other trojans show a flattening ( @xmath15 0 ) , with a turnover near 1.5 @xmath0 m . optical observations show that troilus has a grey spectrum ( @xmath16 4.8%/10@xmath11 ) from 4000 to 9000 where the other six trojans have exclusively red - sloped ( @xmath12 8%/10@xmath11 ) spectra @xcite . could ( 1208 ) troilus , with a distinct nir spectrum , be a special case ? or is troilus representative of the under - studied grey trojan group that shows neutral / grey spectra in the optical and nir ? to address these questions , we obtained nir spectra of four additional optically grey trojans in april and august , 2007 ( table 1 ) , shown in figure [ f4 ] . three out of five of these grey objects are members of the eurybates family , namely ( 3548 ) eurybates , 18060 and 13862 . trojan ( 1208 ) troilus and ( 3451 ) mentor are non - eurybates grey objects in our sample . the five optically grey trojans exhibit very similar nir spectra , with @xmath16 ( 1 to 2 ) % /1000 and @xmath17 0 in the 0.8 @xmath18 2.4 @xmath0 m range . figure [ f4 ] shows that ( 1208 ) troilus is a common grey trojan , in spite of having an inclination ( @xmath19 = 33.5@xmath20 ) , inconsistent with that of the eurypates family ( @xmath21 = 7.2@xmath20 ) . we note that the three eurybates family members show essentially identical nir spectra , within the uncertainties of measurement . since the spectral properties of the three eurybates trojans closely resemble each other , we considered only the spectrum of ( 3548 ) eurybates ( with the highest snr ) for further analyses . the iras albedo of 3548 is 0.054 @xmath22 0.007 @xcite , which is consistent with the common albedos of the main belt c - type asteroids that generally have neutral spectra and low albedos in the optical . the c - types are thought to be composed of hydrated silicates , carbon , and organic compounds @xcite . in particular , it has been suggested that c - type asteroids may be parent bodies for ci and cm carbonaceous chondrites @xcite . accordingly , we compared the spectrum of 3548 , in the wavelength range from 0.8 to 2.45 @xmath0 m , with the laboratory spectra of common carbonaceous meteorites from the brown university keck / nasa relab spectra catalog . we mainly compared our data with the ci and cm chondrite samples , because our grey trojan samples and the c - type asteroids are spectrally alike in the optical . for completeness , we also examined the similarity between ( 3548 ) eurybates and a few other carbonaceous chondrites , such as co and cv meteorites . we further compared our spectra with that of the tagish lake meteorite , which has been independently proposed as a spectral analog of the d - type asteroids @xcite . we searched for spectral analogs to ( 3548 ) eurybates among all the available ci and cm chondrites in the relab database using a @xmath23-test . our results are shown in figure [ f5 ] with all the spectra normalized at @xmath24 m . the spectrum of a laser - irradiated cm2 meteorite ( mighei ) , shown in red , matches the trojan spectrum the best , except for minor discrepancies at 1.4 and 1.9 @xmath0 m which are due to incomplete telluric line removal . the mighei samples were sieved to several partice size fractions and a nd - yag multiple - pulse laser was applied under a vacuum of 10@xmath25 hg @xcite . the reflectance spectra of original mighei samples have neutral spectral slopes and exhibit a major absorption band at 2.7 @xmath0 m and a weak absorption feature at 3.4 @xmath0 m , which are due to phyllosilicates and hydrocarbons respectively . after irradiation , the spectra of processed mighei are significantly reddened and the absorption features are greatly weakened . we found that the spectrum of irradiated mighei coarse powders ( bkr1ma062 , grain size @xmath26 200 @xmath0 m ) fits the spectrum of eurybates the best . mighei is a typical cm2 and its optical albedo was measured to be 0.043 by @xcite . the comparable optical albedos and the similar spectra in the visible and nir are consistent with the idea that grey trojans are compositionally like the cm2 meteorites , being composed of fine - grained phyllosilicate ( clay ) minerals , diamond , silicon carbide , and graphite @xcite . however , we need to point out that the spectral similarity between a featureless astronomical spectrum and a laboratory meteorite spectrum , no matter how suggestive , can never provide definitive proof of the actual mineralogy , given the absence of diagnostic absorption features @xcite . @xcite thoroughly searched for spectral analogs for the trojan emissivity spectra amongst meteorites , minerals and small body spectral databases . they found that neither the thermal ir spectra of the tagish lake meteorite nor of granular mixtures of amorphous silicates with amorphous carbon can reproduce the observed 10 @xmath0 m plateau along with the minor features in the 15 - 30 @xmath0 m region . this is despite the success of these models in the visible and the nir ( 0.4 @xmath27 2.5 @xmath0 m ) @xcite . surprisingly , the mid - infrared ( mir ) spectra of comets , namely hale - bopp and schwassmann - wachmann 1 ( sw1 ) , provide the best match to the trojan thermal spectra , in terms of the overall profile and the alignments of the centers of the emission bands . in contrast to the short history of the thermal observations of asteroids , the 10 @xmath0 m ir emission feature observed in astronomical spectra has been a subject of study for more than 30 years . this feature is believed to be associated with the si - o stretching mode in silicate grains @xcite and the minor features between 16 and 35 @xmath0 m are due to the bending mode of the si - o bond @xcite . numerous investigations have been carried out to characterize the physical properties , such as the mineralogy , crystallinity and grain sizes of silicate particles via fitting synthetic models to these emission features @xcite . the band centers and shapes of the silicate emission features are diagnostic of the mineralogical compositions @xcite . however , the strengths of the emission bands depend primarily upon the temperature of the silicate grains and the temperature , in turn , is controlled by the grain size , the mg / fe ratio and the total amount of incorporated dark materials @xcite . as an example , high quality thermal infrared spectra of comet hale - bopp show that this comet consists of multiple silicate components , such as crystalline pyroxene ( enstatite ) , olivine ( forsterite ) and amorphous silicate groups , with a large fraction of sub - micron grains @xcite . the radiative properties of comets and asteroids must be compared with caution , because multiple scattering is likely to play a more important role in shaping the emissivity spectra from a ( comparatively dense ) regolith than from a coma @xcite . cometary spectra are generated from well - separated particles in an optically - thin coma , although multiple scattering may be important inside `` dust - ball '' particles , consisting of loose aggregates of tiny constituent grains ( kimura et al . the exceptionally good match at 10@xmath0 m between the trojan and cometary spectra appears significant , given that a large number of samples have been considered by @xcite . presumably , the trojan regolith supports a very low density upper layer , in which small silicate particles can be heated by the sun without strong radiative coupling to the denser regolith beneath . fine - grained silicate mixtures ( olivines , pyroxenes , phyllosilicates and carbonates ) can generally reproduce the major features in the trojan spectra , including a blunt emission peak near 10 @xmath0 m and a moderate enhancement in emissivity in the region from 18 to 25 @xmath0 m , although some discrepancy was observed when the minor features were taken into account @xcite . while olivine and pyroxene are consistent with the 10 @xmath0 m emission spectrum , these materials also possess absorption features in the nir , including the characteristic 1-@xmath0 m band . the mir spectra of ( 1172 ) aneas and ( 911 ) agamemnon both exhibit emission features at 10 @xmath0 m but no 1-@xmath0 m band was observed in the nir on these objects ( this paper and @xcite ) . olivine and pyroxene are both ferromagnesian minerals with formula [ ( mg@xmath28fe@xmath29sio@xmath30 and [ ( mg@xmath28fe@xmath29sio@xmath31 respectively , where @xmath32 represents the magnesium abundance . as mentioned earlier , the broad absorption band near 1.0 @xmath0 m is attributed to a crystal field absorption of fe@xmath2 in the silicate structure . thus , the strength of the 1-@xmath0 m absorption band directly depends on the iron abundance in the host silicates , all else being equal . as such , iron - poor silicates have relatively weak 1-@xmath0 m absorption features . in one extreme case , pure enstatite ( mg@xmath33si@xmath33o@xmath34 ) , as an iron - free silicate , appears featureless in the nir with no trace of an absorption band near 1.0 @xmath0 m @xcite . consistently , previous studies of comets have revealed that the observed silicate emission features in the cometary mir spectra are dominated by mg - rich silicate minerals @xcite . moreover , the best fitting silicate model in @xcite consists mainly iron - poor ( or magnesium - rich ) silicates . as such , it is possible that the simultaneous absence of the 1 @xmath0 m silicate absorption and the presence of the 10-@xmath0 m silicate emission is due to the silicate components of those trojans being iron - poor . an immediate problem with the iron - poor interpretation is that low - iron silicates have relatively high albedos @xcite . for example , ( 44 ) nysa is believed to be an iron - depleted asteroid @xcite and the measured geometric albedo of this object is 0.546 @xmath22 0.067 @xcite . in contrast , trojans are very dark objects with an average albedo of @xmath35= 0.041 @xmath22 0.002 @xcite . carbonaceous materials mixed with low - iron silicates might significantly suppress the albedo . however , both carbonaceous materials and pure silicates are spectrally neutral and they are not sufficient to account for the red slopes of trojan spectra . previous studies of trojans @xcite demonstrated that oxidization of ferrous iron carried in amorphous pyroxene can greatly redden the visible and nir spectra of this material . consequently , ferrous - iron bearing silicates were used as the main component by these authors in their models to simulate the trojan spectra . however , if the silicates on trojans are iron - poor , as suggested by the mir observations and the absence of the 1-@xmath0 m band , then the redness of trojan spectra would require other explanations . the origin of the trojan s red color should not be considered in isolation . we must frame this color problem in the context of the whole solar system . a systematic variation of asteroid spectral type with respect to heliocentric distance has been noticed by @xcite with the s - complex mainly located in the inner belt , the c - complex dominating the mid - belt around 3 au and the featureless red d - types mainly found beyond 3.5 au . this original finding is supported by numerous subsequent observations @xcite . in addition , the detection of ultra - red materials on the distant kuiper belt objects @xcite further supports this correlation . this well - established radial distribution of patterned taxonomical types suggests that the compositions of different small body populations are strongly influenced by their distances to the sun , in other words , by their temperatures . it has been proposed that red spectral slopes may be due to a long wavelength wing of a broad uv feature caused by absorption in polycyclic aromatic hydrocarbons @xcite . trojans probably formed beyond 5 au , where temperatures are low enough for dark and red organic matter to be thermodynamically stable . @xcite pointed out that the absence of absorptions in the 3 - 4 @xmath0 m wavelength region limits the possible abundance and species of organics on trojans . however , the quality of the existing 3-micron observations of trojans asteroids is not sufficient to rule out the presence of possible organic materials with weaker absorption bands in the 3 @xmath0 m region . besides organic materials , the carbon - rich ( 4 to 5 wt.% ) tagish lake meteorite exhibits a trojan - like red spectrum in the visible and nir @xcite suggesting ( but not proving ) a carbon - red color connection . no absorption band was detected in the reflectance spectrum of the tagish lake meteorite in the 3 - 4 @xmath0 m region , although an absorption band of oh bond in phyllosilicates was observed at 2.7 @xmath0 m @xcite , a wavelength where few useful ground - based data exist . therefore , trojans may be composed of iron - poor silicates and carbonaceous compounds . we note that the iron - poor silicates scenario is able to explain the non - detection of the 1 @xmath0 m absorption band but it is not a unique explanation . for example , many laboratory investigators have documented that particle size is a crucial parameter that greatly affects reflectance spectra , especially the strength of absorption features @xcite . according to @xcite , the 1 @xmath0 m absorption feature generated by micron - sized particles has a depth @xmath110% of the continuum . such a weak band is susceptible to masking by carbonaceous materials . another possibility is that the crystallinity of silicate grains can also affect the strength of the 1 @xmath0 m absorption band @xcite . the distribution of the optical colors of asteroids beyond 3.3 au shows that the fraction of c - type objects drops rapidly as the heliocentric increases @xcite . infrared observations of the main - belt asteroids reveal that many c - type asteroids exhibit a strong absorption band near 2.9-@xmath0 m that is the diagnostic feature of hydrated silicates , such as phyllosilicates @xcite . as such , many c - type asteroids are thought to have been aqueously alterated , meaning that the chemistry and mineralogy of the host asteroid have been modified by reactions with liquid water @xcite . it has been suggested that the relative lack of c - type asteroids in the hilda and trojan populations is a result of their large heliocentric distances and low equilibrium temperatures , which prevented water ice from melting @xcite . recent studies of trojan dynamical families found that several members in the `` eurybates family '' and the `` 1986wd family '' show c - type like visible spectra . fornasier et al . ( 2007 ) noted that some c - type eurybates trojans show a decreased reflectance at wavelengths @xmath36 . this decline of reflectance in the blue and possibly the ultraviolet ( uv ) regions is similar to the uv absorption ( also known as the `` uv drop - off '' ) that has been widely observed in the spectra of other low - albedo asteroids , and which may be an indicator of past aqueous alteration @xcite . supporting this ( admittedly non - unique ) interpretation , we found that the best analog to the nir spectra of the eurybates family members is given by a cm2 carbonaceous chondrite ( figure 5 ) , an object which is rich in hydrated minerals . in contrast , the observations of the five grey trojans in this study and the observations of seven eurybates family members in @xcite found no evidence of aqueous altered materials . however , given that the strong fundamental absorption bands of water ice and hydrated silicates occur beyond 2.5 @xmath0 m , it is not surprising that current observations of the grey trojans , from 0.5 to 2.5 @xmath0 m , found no evidence of aqueously altered materials . changes in spectral slopes due to the so - called space weathering effect have been inferred in near - earth @xcite and main - belt asteroids @xcite . however , the magnitude and even the sense of the effect depend on many unknown factors , notably the original surface composition . for example , experiments by @xcite show that bombarding complex organic materials with low energy ions ( representing the solar wind ) can neutralize the spectral slopes in the visible and nir wavelength ranges . this reduction of spectral slope may be due to a progressive carbonization of the surface materials @xcite . in contrast , @xcite irradiated frozen ( 16 - 80 k ) methanol ( ch@xmath37oh ) , methane ( ch@xmath38 ) , and benzene ( c@xmath34h@xmath34 ) with ions and found the opposite effect , with the surfaces becoming reddened and darkened due to the formation of an organic ( c - rich ) refractory mantle . these opposite reddening trends would lead to opposite conclusions , if applied to the case of the trojans . work by @xcite would suggest that the spectrally neutral objects are old and rich in carbonaceous compounds , consistent with the evident similarity between the eurybates members and the carbonaceous chondrites . on the contrary , the experiments of @xcite would lead to the interpretation that the eurybates family is young and unweathered . the observation that the eurybates family forms a tight cluster within the menelaus clan @xcite suggests a younger age for the eurybates members , consistent with the latter interpretation . our understanding of the effects of space weathering remains very limited . more laboratory studies of space weathering on icy or organic - rich materials are needed . more importantly , high quality observations of trojan asteroids in the ir wavelength regions ( especially near 3-@xmath0 m and 10-@xmath0 m , where the diagnostic absorption features lie ) , will be key to understanding the nature of trojan asteroids . if future observations of the c - type trojans at longer wavelengths reveal hydrated minerals , this would set a strong constraint on the chemical and thermal evolution of the trojan population , because liquid water can only exist under particular conditions of temperature and pressure . we obtained new , high quality near - infrared reflection spectra of eleven jovian trojan asteroids , with the following results : * no 1-@xmath0 m silicate absorption feature ( deeper than about 1% of the local continuum ) was found , in contradiction to previously reported spectra showing this band in these objects @xcite . * one of the seven objects ( 1172 aneas ) does show a thermal emission spectrum consistent with silicate particles ( emery et al . the simultaneous presence of a silicate feature at 10 @xmath0 m and absence of one at 1 @xmath0 m can be understood if the silicates are iron - poor . but , if so , the red color of the trojans is more likely to be due to organics than to oxidized iron ( opposite to the conclusion of cruikshank et al . * the near infrared spectra of the optically neutral trojans ( the eurybates family members ) are consistent with that of a cm2 carbonaceous chondrite , which hints that these c - type trojans may contain aqueous altered materials . the authors would like to thank ellen howell , paul lucey and edward cloutis for their valuable discussions and constructive suggestions . the authors also would like to thank zahed wahhaj and rachel stevenson for reading and commenting on the manuscript . we especially thank the referee josh emery for his careful review and constructive comments . by was visiting astronomer at the infrared telescope facility , which is operated by the university of hawaii under cooperative agreement no . nnx-08ae38a with the national aeronautics and space administration , science mission directorate , planetary astronomy program . by was supported by the national aeronautics and space administration through the nasa astrobiology institute under cooperative agreement no . nna08da77a issued through the office of space science and by a grant to david jewitt from the nasa origins program . lllllllll ( 884 ) priamus & 2007 apr . 06 & 15.75 & 3.34 & 5.093 & 4.129 & 120 x 12 & 1.15 - 1.16 & sa1021081 + ( 884 ) priamus & 2007 apr . 07 & 15.76 & 3.50 & 5.092 & 4.132 & 120 x 10 & 1.21 - 1.26 & hd94270 + ( 1172 ) aneas & 2007 apr . 06 & 15.43 & 3.21 & 5.275 & 4.311 & 120 x 10 & 1.31 - 1.31 & hd115642 + ( 1172 ) aneas & 2007 apr . 07 & 15.44 & 3.25 & 5.274 & 4.311 & 120 x 8 & 1.33 - 1.35 & hd115642 + ( 1208 ) troilus & 2007 apr . 07 & 16.43 & 3.67 & 5.617 & 4.671 & 120 x 20 & 1.34 - 1.63 & hd124019 + ( 1208 ) troilus & 2007 apr . 07 & 16.43 & 3.60 & 5.616 & 4.668 & 120 x 20 & 1.20 - 1.44 & hd124019 + ( 2207 ) antenor & 2007 apr . 06 & 15.71 & 1.31 & 5.140 & 4.145 & 120 x 10 & 1.19 - 1.25 & sa105 - 56 + ( 2207 ) antenor & 2007 apr . 07 & 15.70 & 1.20 & 5.140 & 4.144 & 120 x 10 & 1.13 - 1.16 & sa105 - 56 + ( 2223 ) sarpedon & 2007 apr . 06 & 16.38 & 2.74 & 5.168 & 4.192 & 120 x 20 & 1.23 - 1.26 & hd115642 + ( 2223 ) sarpedon & 2007 apr . 07 & 16.36 & 2.54 & 5.168 & 4.188 & 120 x 20 & 1.23 - 1.25 & hd115642 + ( 2241 ) alcathous & 2007 apr . 06 & 15.56 & 6.06 & 4.879 & 3.994 & 120 x 12 & 1.25 - 1.29 & hd94562 + ( 2241 ) alcathous & 2007 apr . 07 & 15.57 & 6.21 & 4.879 & 4.000 & 120 x 10 & 1.37 - 1.45 & hd94562 + ( 2357 ) phereclos & 2007 apr . 06 & 15.55 & 0.19 & 5.057 & 4.056 & 120 x 10 & 1.17 - 1.22 & sa105 - 56 + ( 3451 ) mentor & 2007 apr . 06 & 15.03 & 1.80 & 5.205 & 4.215 & 120 x 10 & 1.32 - 1.43 & sa105 - 56 + ( 3451 ) mentor & 2007 apr . 07 & 15.03 & 1.81 & 5.205 & 4.214 & 120 x 11 & 1.19 - 1.28 & sa105 - 56 + ( 3548 ) eurybates & 2007 aug . 06 & 16.63 & 5.01 & 5.175 & 4.246 & 120 x 20 & 1.31 - 1.51 & hd221495 + ( 3548 ) eurybates & 2007 aug . 07 & 16.62 & 4.83 & 5.174 & 4.239 & 120 x 16 & 1.25 - 1.26 & hd213199 + 13862 ( 1999 xt160 ) & 2007 aug . 06 & 17.91 & 0.06 & 5.303 & 4.288 & 120 x 18 & 1.34 - 1.59 & hd221495 + 18060 ( 1999 xj156 ) & 2007 aug . 06 & 16.63 & 2.40 & 5.039 & 4.042 & 120 x 18 & 1.16 - 1.25 & hd198259 + 18060 ( 1999 xj156 ) & 2007 aug . 07 & 16.62 & 2.56 & 5.038 & 4.045 & 120 x 24 & 1.16 - 1.23 & hd207079 + lcc ( 884 ) priamus & 4.3 % & @xmath391 % + ( 1172 ) aneas & 14.1 % & @xmath391 % + ( 1208 ) troilus & 18.9 % & @xmath391 % + ( 2207 ) antenor & 5.1 % & @xmath391 % + ( 2223 ) sarpedon & 28.9 % & @xmath391 % + ( 2241 ) alcathous & 2.7 % & @xmath391 % + ( 2357 ) phereclos & 4.1 % & @xmath391 % + [ abs_lim ] m. dashed lines are cubic spline fits to the howell data , added to guide the eye.,title="fig:",width=432 ] m. dashed lines are cubic spline fits to the howell data , added to guide the eye.,title="fig:",width=432 ] m. the spectra have been vertically offset for clarity . no significant features are present . the minor absorptions near 1.1 , 1.4 and 2.0 @xmath0 m are due to the incomplete telluric calibration . no silicate absorption features are detected at 1.0 and 2.0 @xmath0 m . , width=624 ]

we obtained near - infrared ( 0.8 - 2.5 @xmath0 m ) spectra of seven jovian trojan asteroids that have been formerly reported to show silicate - like absorption features near 1-@xmath0 m . our sample includes the trojan ( 1172 ) aneas , which is one of three trojans known to possess a comet - like 10-@xmath0 m emission feature , indicative of fine - grained silicates . our observations show that all seven trojans appear featureless in high signal - to - noise ratio spectra . the simultaneous absence of the 1-@xmath0 m band and presence of the 10 @xmath0 m emission can be understood if the silicates on ( 1172 ) aneas are iron - poor . + in addition , we present near infrared observations of five optically grey trojans , including three objects from the collisionally produced eurybates family . the five grey trojans appear featureless in the near infrared with no diagnostic absorption features . the near infrared spectrum of eurybates can be best fitted with the spectrum of a cm2 carbonaceous chondrite , which hints that the c - type eurybates family members may have experienced aqueous alteration .

SECTION 1. SHORT TITLE. This Act may be cited as the ``Secure Handling of Ammonium Nitrate Act of 2005''. SEC. 2. FINDINGS. Congress finds the following: (1) Although ammonium nitrate is an important fertilizer used in agricultural production, in the wrong hands, ammonium nitrate can be used to create explosives and was so used in terrorist attacks conducted in Oklahoma City, Bali, and Istanbul. (2) The production, importation, storage, sale, and distribution of ammonium nitrate affects interstate and intrastate commerce. (3) It is necessary for the Secretary of Homeland Security to regulate the production, storage, sale, and distribution of ammonium nitrate on account of the prior use of ammonium nitrate to create explosives used in acts of terrorism and to prevent terrorists from acquiring ammonium nitrate to create explosives. SEC. 3. DEFINITIONS. In this Act: (1) Act.--The term ``this Act'' includes regulations issued under this Act. (2) Ammonium nitrate.--The term ``ammonium nitrate'' means solid ammonium nitrate that is chiefly the ammonium salt of nitric acid and contains not less than 33 percent nitrogen, of which-- (A) 50 percent is in ammonium form; and (B) 50 percent is in nitrate form. (3) Facility.--The term ``facility'' means any site where ammonium nitrate is produced, stored, or held for distribution, sale, or use. The term includes-- (A) all buildings or structures used to produce, store, or hold ammonium nitrate for distribution, sale, or use at a single site; and (B) multiple sites described in subparagraph (A), if the sites are-- (i) contiguous or adjacent; and (ii) owned or operated by the same person. (4) Handle.--The term ``handle'' means to produce, store, sell, or distribute ammonium nitrate. (5) Handler.--The term ``handler'' means any person that produces, stores, sells, or distributes ammonium nitrate. (6) Purchaser.--The term ``purchaser'' means any person that purchases ammonium nitrate. (7) Terrorism.--The term ``terrorism'' has the meaning given that term in section 2(15) of the Homeland Security Act of 2002 (6 U.S.C. 101(15)). (8) Secretary.--The term ``Secretary'' means the Secretary of Homeland Security. SEC. 4. REGULATION OF HANDLING AND PURCHASE OF AMMONIUM NITRATE. (a) In General.--The Secretary may regulate the handling and purchase of ammonium nitrate to prevent the misappropriation or use of ammonium nitrate in an act of terrorism. (b) Regulations.--The Secretary may promulgate regulations that require-- (1) handlers-- (A) to register facilities; (B) to sell or distribute ammonium nitrate only to handlers and purchasers registered under this Act; and (C) to maintain records of sale or distribution that include the name, address, telephone number, and registration number of the immediate subsequent purchaser of ammonium nitrate; and (2) purchasers to be registered. (c) Use of Previously Submitted Information.--Prior to requiring a facility or handler to submit new information for registration under this section, the Secretary shall-- (1) request from the Attorney General, and the Attorney General shall provide, any information previously submitted to the Attorney General by the facility or handler under section 843 of title 18, United States Code; and (2) at the election of the facility or handler-- (A) use the license issued under that section in lieu of requiring new information for registration under this section; and (B) consider the license to fully comply with the requirement for registration under this section. (d) Consultation.--In promulgating regulations under this section, the Secretary shall consult with the Secretary of Agriculture to ensure that the access of agricultural producers to ammonium nitrate is not unduly burdened. (e) Data Confidentiality.--Notwithstanding section 552 of title 5, United States Code, or the USA PATRIOT ACT (Public Law 107-56; 115 Stat. 272) or an amendment made by that Act, the Secretary may not disclose to any person any information obtained from any facility, handler, or purchaser-- (1) regarding any action taken, or to be taken, at the facility or by the handler or purchaser to ensure the secure handling of ammonium nitrate; or (2) that would disclose-- (A) the identity or address of any purchase of ammonium nitrate; (B) the quantity of ammonium nitrate purchased; or (C) the details of the purchase transaction. (f) Exceptions to Data Confidentiality.--The Secretary may disclose any information described in subsection (e)-- (1) to an officer or employee of the United States, or a person that has entered into a contract with the United States, who needs to know the information to perform the duties of the officer, employee, or person, or to a State agency pursuant to an arrangement under section 6, under appropriate arrangements to ensure the protection of the information; (2) to the public, to the extent the Secretary specifically finds that disclosure of particular information is required in the public interest; or (3) to the extent required by order of a Federal court in a proceeding in which the Secretary is a party, under such protective measures as the court may prescribe. SEC. 5. ENFORCEMENT. (a) Inspections.--The Secretary, without a warrant, may enter any place during business hours that the Secretary believes may handle ammonium nitrate to determine whether the handling is being conducted in accordance with this Act. (b) Prevention of Sale or Distribution Order.--In any case in which the Secretary has reason to believe that ammonium nitrate has been handled other than in accordance with this Act, the Secretary may issue a written order preventing any person that owns, controls, or has custody of the ammonium nitrate from selling or distributing the ammonium nitrate. (c) Appeal Procedures.-- (1) In general.--A person subject to an order under subsection (b) may request a hearing to contest the order, under such administrative adjudication procedures as the Secretary may establish. (2) Rescission.--If an appeal under paragraph (1) is successful, the Secretary shall rescind the order. (d) In Rem Proceedings.--The Secretary may institute in rem proceedings in the United States district court for the district in which the ammonium nitrate is located to seize and confiscate ammonium nitrate that has been handled in violation of this Act. SEC. 6. ADMINISTRATIVE PROVISIONS. (a) Cooperative Agreements.--The Secretary may enter into a cooperative agreement with the Secretary of Agriculture, or the head of any State department of agriculture or other State agency that regulates plant nutrients, to carry out this Act, including cooperating in the enforcement of this Act through the use of personnel or facilities. (b) Delegation.-- (1) In general.--The Secretary may delegate to a State the authority to assist the Secretary in the administration and enforcement of this Act. (2) Delegation required.--On the request of a Governor of a State, the Secretary shall delegate to the State the authority to carry out section 4 or 5, on a determination by the Secretary that the State is capable of satisfactorily carrying out that section. (3) Funding.--If the Secretary enters into an agreement with a State under this subsection to delegate functions to the State, the Secretary shall provide to the State adequate funds to enable the State to carry out the functions. (4) Inapplicability.--Notwithstanding any other provision of this subsection, this subsection does not authorize a State to carry out a function under section 4 or 5 relating to a facility or handler in the State that makes the election described in section 4(c)(2). SEC. 7. CIVIL LIABILITY. (a) Unlawful Acts.--It is unlawful for any person-- (1) to fail to perform any duty required by this Act; (2) to violate the terms of registration under this Act; (3) to fail to keep any record, make any report, or allow any inspection required by this Act; or (4) to violate any sale or distribution order issued under this Act. (b) Penalties.-- (1) In general.--A person that violates this Act may only be assessed a civil penalty by the Secretary of not more than $50,000 per violation. (2) Notice and opportunity for a hearing.--No civil penalty shall be assessed under this Act unless the person charged has been given notice and opportunity for a hearing on the charge in the county, parish, or incorporated city of residence of the person charged. (c) Jurisdiction Over Actions for Civil Damages.--The district courts of the United States shall have exclusive jurisdiction over any action for civil damages against a handler for any harm or damage that is alleged to have resulted from the use of ammonium nitrate in violation of law that occurred on or after the date of enactment of this Act. SEC. 8. STATE LAW PREEMPTION. This Act preempts any State law that regulates the handling of ammonium nitrate to prevent the misappropriation or use of ammonium nitrate in an act of terrorism.

Secure Handling of Ammonium Nitrate Act of 2005 - Authorizes the Secretary of Homeland Security to regulate the handling and purchase of ammonium nitrate to prevent its misappropriation or use in an act of terrorism. Authorizes the Secretary to promulgate regulations that require: (1) handlers to register facilities, to sell or distribute ammonium nitrate only to registered handlers and purchasers, and maintain records of sale or distribution that include the name, address, telephone number, and registration number of the immediate subsequent purchaser of ammonium nitrate; and (2) registration of purchasers. Authorizes the Secretary to make warrantless inspections during business hours of any place that may handle ammonium nitrate to determine whether such handling accords with this Act. Makes it unlawful for any person to: (1) fail to perform any duty required by this Act and related regulations; (2) violate the terms of registration under this Act; (3) fail to keep any record, make any report, or allow any inspection required by this Act; or (4) violate any sale or distribution order issued under this Act. Establishes civil penalties for violations.

I received a call Monday night from Roger Stone, the infamous political prankster and Donald Trump confidant. He wanted to talk about Anthony Scaramucci, whose 10-day tenure as White House communications director had just ended in ignominy. Stone said that Scaramucci reminded him of “a suicide bomber,” then switched centuries for his next metaphor. “The administration is like the French Revolution,” Stone said. “You never know who will be beheaded next.” But Stone didn’t believe that Scaramucci would stay far from the president for long. “As you know, none of us are ever really gone. He still has the president’s cellphone, the president’s private number. Just because he’s not in the White House, no one should think his influence has gone.” When I spoke to Scaramucci on Tuesday afternoon, the financier was more interested in justifying his recent past. From the beginning of his time in the Trump White House, way back on July 20, critics said that Scaramucci was too similar to Trump, too eager to be on TV, to last. Scaramucci was keenly aware of that particular liability. It explains why his opening news conference was so filled with compliments for the president. He knew there was only one person watching whose opinion of him mattered. “The president thought I killed it,” Scaramucci told me the following day, still clearly hyped up by his experience in the White House briefing room. The administration is like the French Revolution. You never know who will be beheaded next. Republican strategist Roger Stone “If you were 7 inches taller, I’d be worried,” Trump told Scaramucci, according to someone familiar with the conversation who asked not to be named quoting the president. The euphoria wouldn’t last long. A Politico reporter alerted Scaramucci that Ryan Lizza of The New Yorker tweeted Wednesday night that Scaramucci was at dinner with the president, first lady Melania Trump, Fox News host Sean Hannity and former Fox News co-president Bill Shine. Scoop: Trump is dining tonight w/Sean Hannnity, Bill Shine (former Fox News executive), & Anthony Scaramucci, per to 2 knowledgeable sources — Ryan Lizza (@RyanLizza) July 26, 2017 Senior White House official tells me that Melania was also at the dinner tonight with Trump, Hannity, Shine, and Scaramucci. — Ryan Lizza (@RyanLizza) July 27, 2017 Scaramucci was livid about the information being passed on to a reporter. For one thing, he said the guest list was incomplete. The tweets didn’t mention the presence of Ainsley Earhardt and Brian Kilmeade, co-hosts of “Fox & Friends,” as well as White House counselor Kellyanne Conway and Vice President Mike Pence, who, he said, left before the sit-down dinner. For another, he knew that the full guest list also included Kimberly Guilfoyle, co-host of “The Five” on Fox News. Early the next morning, Olivia Nuzzi of New York Magazine confirmed that Guilfoyle was there. A source close to Scaramucci tells me that additionally, Kimberly Guilfoyle, the Fox News host, was there. https://t.co/vMz3lVNP5K — Olivia Nuzzi (@Olivianuzzi) July 27, 2017 Scaramucci realized that the inclusion of Guilfoyle would raise suspicion. He said he was aware that some associates and members of the media were gossiping about his friendship with the Fox host and feared this particular connection would only make matters worse. He said he took it as “an attack.” Scaramucci strongly denies having a sexual relationship with Guilfoyle. Stone, a friend of Guilfoyle’s, explained that Scaramucci and Guilfoyle “are very close friends but nothing more.” He added, “He is way too short for Kimberly.” Through a Fox News spokesperson, Guilfoyle said she’s known Scaramucci for years through her work at Fox News and the two are “good friends.” As soon as Scaramucci returned from Wednesday night’s dinner, he called Lizza and gave his now-infamous interview, published Thursday, in which he suggested that former White House Chief of Staff Reince Priebus was a “paranoid schizophrenic” and that White House chief strategist Steve Bannon practiced auto-fellatio. Scaramucci said he felt burned by the interview. “The Lizzas and Scaramuccis have been friends for over 50 years. My dad knew his dad from construction, and we were building a personal relationship. Most of what I said was humorous and joking. Legally, it may have been on the record, but the spirit of it was off. And he knew that.” Still, Scaramucci told me, he has plans to take Lizza out for a beer. Most of what I said was humorous and joking. Legally, it may have been on the record, but the spirit of it was off. And he knew that. Anthony Scaramucci on The New Yorker interview When I asked Lizza for his response, he wrote back: “I’ve only known Anthony in his capacity as a Trump surrogate and then White House communications director. We are not and have never been ‘old family friends,’ though I think our fathers knew each other, so maybe that’s what he’s talking about. (The Long Island Italian world in that generation is relatively small.) But again, that would not be a reason to suppress an explosive on-the-record interview.” According to several sources close to the White House, the president was initially amused by the Lizza exchange but changed his opinion when he saw how much negative attention it was bringing. Scaramucci said he offered to resign before the weekend. The president told him that wouldn’t be necessary, but he instructed Scaramucci to “watch it” in the future, according to someone familiar with the conversation. I spoke with Scaramucci on Saturday morning, and he sounded defeated. “I think I have strep,” he said. On top of everything else, the night before, The New York Post had broken the news of his impending divorce from his second wife, Deidre Ball. Jonathan Ernst / Reuters White House communications director Anthony Scaramucci arrives with President Donald Trump aboard Air Force One in Ronkonkoma, New York, on Friday. On Monday, Scaramucci was out of a job. That Scaramucci’s marriage was in trouble was hardly a secret. Long before Ball filed for divorce on July 6, Scaramucci was open with friends and associates about what he believed to be the sorry state of their union and how they were struggling through regular counseling sessions. He just hated that his relationship was being discussed in public. A follow-up report from the Post said that Scaramucci didn’t attend the birth of their son last week. Instead, he sent Ball a short congratulatory text. Scaramucci said this is an unfair characterization of events. He told me that Ball’s due date was Aug. 9, so when he boarded Air Force One to West Virginia last Monday to attend the president’s address at the National Scout Jamboree, he didn’t think he’d be in danger of missing the birth. As soon as she texted him that she was going into labor, he said, he looked into chartering a plane from West Virginia but discovered that there was a wide no fly-zone around Air Force One. He explained that he decided to wait to fly back to Washington with the president, then travel to New York from there. As of Tuesday afternoon, he still hadn’t met his son. Scaramucci claimed that right after the birth Ball texted him her request for some space. When I asked about this text, Ball’s lawyer, Jill Stone, responded: “Any texts of that nature had nothing to do with the baby or seeing the baby.” (Jill Stone said she couldn’t comment on the rest of Scaramucci’s version of events.) When I spoke to Scaramucci on Saturday, he didn’t have much to say about the collapse of his marriage. “It’s fine. I mean, what am I going to do?” He perked up when he started talking about the fantastic team he was going to bring into the White House’s communications shop and the big plans he was going to enact after a tumultuous first week. But on Monday morning, Scaramucci knew he was cooked. Retired Marine Gen. John Kelly, the new chief of staff, who insisted that all White House staff report to him, asked for his resignation. “It was a very polite conversation,” Scaramucci says. Scaramucci then went to see Trump, who was unavailable. He ended up speaking with the president, his daughter Ivanka Trump and his son-in-law, Jared Kushner, separately later in the day by telephone. All were gracious, he said. “The president told me he knows I have his back, but he has to try to tighten the ship.” So what are you going to do next, I asked him. “I am now going to go dark,” he said. And then? “Then I will reemerge.” He paused. “As me.” ||||| Anthony Scaramucci Moocho Dinero Waiting After D.C. On Public Speaking Circuit Anthony Scaramucci Can Turn White House Debacle into $75k Speaking Engagements EXCLUSIVE Anthony Scaramucci's absurdly brief gig in the White House is going to pay off big-time, and help make the rich man even richer ... IF he chooses to cash in on making speeches. Multiple sources plugged into the public speaking circuit tell us the Mooch is such a hot ticket right now, he could haul in $75,000 per event. We're told his market value as a hedge fund magnate and entrepreneur already made his speaking engagements worth roughly $25-50k -- but those 10 days in the West Wing make him a bigger draw, which means way more dough. Our sources say the high drama around his administration stint adds extra appeal ... especially if he wanted to play the "sacrificial lamb." However, it's doubtful Scaramucci would turn on Trump in speeches just to make a buck. He's got plenty of money, and most D.C. insiders agree loyalty to the Prez wasn't his issue. Bottom line -- Mooch is in position to clean up, and -- as they say -- come out smelling like a rose. ||||| I received a call Monday night from Roger Stone, the infamous political prankster and Donald Trump confidant. He wanted to talk about Anthony Scaramucci, whose 10-day tenure as White House communications director had just ended in ignominy. Stone said that Scaramucci reminded him of “a suicide bomber,” then switched centuries for his next metaphor. “The administration is like the French Revolution,” Stone said. “You never know who will be beheaded next.” But Stone didn’t believe that Scaramucci would stay far from the president for long. “As you know, none of us are ever really gone. He still has the president’s cellphone, the president’s private number. Just because he’s not in the White House, no one should think his influence has gone.” When I spoke to Scaramucci on Tuesday afternoon, the financier was more interested in justifying his recent past. From the beginning of his time in the Trump White House, way back on July 20, critics said that Scaramucci was too similar to Trump, too eager to be on TV, to last. Scaramucci was keenly aware of that particular liability. It explains why his opening news conference was so filled with compliments for the president. He knew there was only one person watching whose opinion of him mattered. “The president thought I killed it,” Scaramucci told me the following day, still clearly hyped up by his experience in the White House briefing room. The administration is like the French Revolution. You never know who will be beheaded next. Republican strategist Roger Stone “If you were 7 inches taller, I’d be worried,” Trump told Scaramucci, according to someone familiar with the conversation who asked not to be named quoting the president. The euphoria wouldn’t last long. A Politico reporter alerted Scaramucci that Ryan Lizza of The New Yorker tweeted Wednesday night that Scaramucci was at dinner with the president, first lady Melania Trump, Fox News host Sean Hannity and former Fox News co-president Bill Shine. Scoop: Trump is dining tonight w/Sean Hannnity, Bill Shine (former Fox News executive), & Anthony Scaramucci, per to 2 knowledgeable sources — Ryan Lizza (@RyanLizza) July 26, 2017 Senior White House official tells me that Melania was also at the dinner tonight with Trump, Hannity, Shine, and Scaramucci. — Ryan Lizza (@RyanLizza) July 27, 2017 Scaramucci was livid about the information being passed on to a reporter. For one thing, he said the guest list was incomplete. The tweets didn’t mention the presence of Ainsley Earhardt and Brian Kilmeade, co-hosts of “Fox & Friends,” as well as White House counselor Kellyanne Conway and Vice President Mike Pence, who, he said, left before the sit-down dinner. For another, he knew that the full guest list also included Kimberly Guilfoyle, co-host of “The Five” on Fox News. Early the next morning, Olivia Nuzzi of New York Magazine confirmed that Guilfoyle was there. A source close to Scaramucci tells me that additionally, Kimberly Guilfoyle, the Fox News host, was there. https://t.co/vMz3lVNP5K — Olivia Nuzzi (@Olivianuzzi) July 27, 2017 Scaramucci realized that the inclusion of Guilfoyle would raise suspicion. He said he was aware that some associates and members of the media were gossiping about his friendship with the Fox host and feared this particular connection would only make matters worse. He said he took it as “an attack.” Scaramucci strongly denies having a sexual relationship with Guilfoyle. Stone, a friend of Guilfoyle’s, explained that Scaramucci and Guilfoyle “are very close friends but nothing more.” He added, “He is way too short for Kimberly.” Through a Fox News spokesperson, Guilfoyle said she’s known Scaramucci for years through her work at Fox News and the two are “good friends.” As soon as Scaramucci returned from Wednesday night’s dinner, he called Lizza and gave his now-infamous interview, published Thursday, in which he suggested that former White House Chief of Staff Reince Priebus was a “paranoid schizophrenic” and that White House chief strategist Steve Bannon practiced auto-fellatio. Scaramucci said he felt burned by the interview. “The Lizzas and Scaramuccis have been friends for over 50 years. My dad knew his dad from construction, and we were building a personal relationship. Most of what I said was humorous and joking. Legally, it may have been on the record, but the spirit of it was off. And he knew that.” Still, Scaramucci told me, he has plans to take Lizza out for a beer. Most of what I said was humorous and joking. Legally, it may have been on the record, but the spirit of it was off. And he knew that. Anthony Scaramucci on The New Yorker interview When I asked Lizza for his response, he wrote back: “I’ve only known Anthony in his capacity as a Trump surrogate and then White House communications director. We are not and have never been ‘old family friends,’ though I think our fathers knew each other, so maybe that’s what he’s talking about. (The Long Island Italian world in that generation is relatively small.) But again, that would not be a reason to suppress an explosive on-the-record interview.” According to several sources close to the White House, the president was initially amused by the Lizza exchange but changed his opinion when he saw how much negative attention it was bringing. Scaramucci said he offered to resign before the weekend. The president told him that wouldn’t be necessary, but he instructed Scaramucci to “watch it” in the future, according to someone familiar with the conversation. I spoke with Scaramucci on Saturday morning, and he sounded defeated. “I think I have strep,” he said. On top of everything else, the night before, The New York Post had broken the news of his impending divorce from his second wife, Deidre Ball. Jonathan Ernst / Reuters White House communications director Anthony Scaramucci arrives with President Donald Trump aboard Air Force One in Ronkonkoma, New York, on Friday. On Monday, Scaramucci was out of a job. That Scaramucci’s marriage was in trouble was hardly a secret. Long before Ball filed for divorce on July 6, Scaramucci was open with friends and associates about what he believed to be the sorry state of their union and how they were struggling through regular counseling sessions. He just hated that his relationship was being discussed in public. A follow-up report from the Post said that Scaramucci didn’t attend the birth of their son last week. Instead, he sent Ball a short congratulatory text. Scaramucci said this is an unfair characterization of events. He told me that Ball’s due date was Aug. 9, so when he boarded Air Force One to West Virginia last Monday to attend the president’s address at the National Scout Jamboree, he didn’t think he’d be in danger of missing the birth. As soon as she texted him that she was going into labor, he said, he looked into chartering a plane from West Virginia but discovered that there was a wide no fly-zone around Air Force One. He explained that he decided to wait to fly back to Washington with the president, then travel to New York from there. As of Tuesday afternoon, he still hadn’t met his son. Scaramucci claimed that right after the birth Ball texted him her request for some space. When I asked about this text, Ball’s lawyer, Jill Stone, responded: “Any texts of that nature had nothing to do with the baby or seeing the baby.” (Jill Stone said she couldn’t comment on the rest of Scaramucci’s version of events.) When I spoke to Scaramucci on Saturday, he didn’t have much to say about the collapse of his marriage. “It’s fine. I mean, what am I going to do?” He perked up when he started talking about the fantastic team he was going to bring into the White House’s communications shop and the big plans he was going to enact after a tumultuous first week. But on Monday morning, Scaramucci knew he was cooked. Retired Marine Gen. John Kelly, the new chief of staff, who insisted that all White House staff report to him, asked for his resignation. “It was a very polite conversation,” Scaramucci says. Scaramucci then went to see Trump, who was unavailable. He ended up speaking with the president, his daughter Ivanka Trump and his son-in-law, Jared Kushner, separately later in the day by telephone. All were gracious, he said. “The president told me he knows I have his back, but he has to try to tighten the ship.” So what are you going to do next, I asked him. “I am now going to go dark,” he said. And then? “Then I will reemerge.” He paused. “As me.”

– After what TMZ calls an "absurdly brief gig" in the White House, Anthony Scaramucci may soon be enjoying big bucks from speaking engagements. Scaramucci, who was a White House fixture for less time than it takes for milk to spoil, could be getting a hefty ROI from his short stint as communications director, with "multiple sources plugged into the public speaking circuit" telling TMZ he could command $75,000 for each speaking gig, in no small part due to the drama that surrounded his short tenure. TMZ doesn't think Scaramucci would actually dish on Trump—it notes Scaramucci's apparent loyalty and already fat bank account—but it says he could cash in if he wanted to, especially if he were willing to play the part of "sacrificial lamb." Meanwhile, Vicky Ward of HuffPost spoke with Scaramucci on Tuesday, and he told her "most" of what he said in his infamous call to New Yorker reporter Ryan Lizza "was humorous and joking." He also says Lizza threw him under the bus—their families have been friends for more than 50 years, he claims—and that "legally, [the interview] may have been on the record, but the spirit of it was off. And [Lizza] knew that." (Lizza, for his part, tells Ward: "We are not and have never been 'old family friends,' though I think our fathers knew each other.") Scaramucci also revealed his next steps: He's going to "go dark," then "re-emerge—as me." Ward also chatted with Trump surrogate Roger Stone, who told her Trump's administration is "like the French Revolution. You never know who will be beheaded next." (Scaramucci talks about his marital woes and his last hours in the White House here.)

the munics project is a wide area @xmath0-band selected photometric survey in the @xmath7 passbands aiming at two main scientific goals , namely * the identification of galaxy clusters at redshifts around unity , and * the selection of a fair sample of field early - type galaxies at similar redshifts for evolutionary studies . near - ir selection is an efficient tool for tracing the massive galaxy population at redshifts around unity because of its high sensitivity for evolved stellar populations even in the presence of moderate star formation activity . thus a @xmath8-band selected survey can provide a very useful database for the investigation of the formation and evolution of the cluster as well as the field population of massive galaxies . clusters of galaxies are of prime interest in extragalactic astronomy and cosmology . the @xmath9 evolution of their number density and correlation function are sensitive tests for structure formation theories and especially the density parameter @xmath10 . models of structure formation predict that if @xmath11 , the number density of clusters of richness class 1 declines by a factor of @xmath12 between @xmath13 and @xmath14 . on the other hand , if @xmath15 , the number density declines only by a factor of @xmath16 in the same redshift range ( eke , cole , & frenk 1996 ; bahcall , fan , & cen 1997 ; fan , bahcall , & cen 1997 ) . furthermore , clusters of galaxies allow to find large numbers of massive galaxies at higher redshift and thus represent unique laboratories to study the evolution of galaxies in high density regions as a function of redshift . while the number of clusters known at redshifts @xmath17 is steadily increasing , _ uniformly selected _ samples of clusters at high redshift are still deficient in the optical and near - ir wavelength ranges . the formation and evolution of the population of massive galaxies is still a matter of lively and controversial debate . no general agreement has been reached yet regarding the formation era of spheroidals . while models of hierarchical galaxy formation ( cole et al . 1993 ; kauffman & charlot 1998 ) consistently predict a steep decline in the number density of massive spheroidals , they have a rather large number of free parameters , some of which involve ill - understood processes . observation has not yet been successful in constraining the ranges of the involved model parameters tightly enough , so that comparisons between theory and experiment are difficult to interpret . moreover , measuring the evolution of the number density of early - type galaxies @xmath18 to redshifts of unity is by itself a difficult undertaking , suffering from too small samples and strong selection effects , therefore yielding contradictory results ( e.g. totani & yoshii 1998 ; benitez et al . 1999 ; shade et al . 1999 ; broadhurst & bouwens 1999 ; barger et al . the munics project uniformly covers 1 square degree in the @xmath1 and @xmath0 near - ir bands . the survey area consists of 8 @xmath19 randomly selected fields at high galactic latitude , as well as 13 @xmath20 fields targeted towards @xmath6 qsos . the @xmath5 detection limits for a point source are @xmath21 in the @xmath0-band and @xmath22 in the @xmath1-band . the data have been acquired at the 3.5 m telescope at calar alto observatory using the @xmath23 camera . optical photometry in the @xmath2 , @xmath3 , and @xmath4 bands was obtained for a subsample of the survey fields covering 0.35 square degrees in total . these data have been obtained at the 2.2 m telescope at calar alto observatory and the 2.7 m telescope at mcdonald observatory . these data will enable us to determine photometric redshifts for the galaxies and thus are of great importance in selecting and confirming cluster candidates as well as individual galaxies for follow - up spectroscopy . figure 1 shows @xmath0 vs. @xmath24 color magnitude diagrams for population synthesis models based on the bruzual & charlot 1995 code ( bruzual & charlot 2000 ) , together with a subsample of the munics data . note that the @xmath24 color of a late m - type star is @xmath25 , and therefore any object having redder color must be redshifted , with the exception of extreme stellar objects like brown dwarfs . those are not expected to be very numerous down to our sensitivity limits . therefore the @xmath24 color is a very powerful selection tool for picking out the evolved populations of massive galaxies at redshifts around unity and larger . figure 2 ( right panel ) shows the photometric redshift distribution of 371 galaxies which were detected in _ all _ 5 passbands in a small subarea of @xmath26 and have a @xmath24 color @xmath27 , confirming the usefulness of the @xmath24 selection . the left panel demonstrates that we can reliably reconstruct the sed of early - type galaxies at high redshift from our @xmath28 data . data reduction and calibration of the near - ir data is completed and reduction of the optical data is almost completed . here we present first results regarding detection of clusters and the surface density of eros . the surface density of extremely red objetcs ( eros ) defined in terms of @xmath24 as determined from 0.35 square degrees of data is given in table 1 . as soon as the optical data become fully available further investigation of the nature of such objects will be possible , as well as comparisons to previous studies which mostly use @xmath29 or @xmath30 for defining eros , and have surveyed much smaller areas at comparable depth . .surface densities as a function of @xmath24 color as derived from a total of 0.35 square degrees . [ cols="^,>,<",options="header " , ] assuming that the @xmath24 and @xmath31 colors for lbds 53w091 ( spinrad et al . 1997 ) are typical for eros , all objects with @xmath32 have to be considered as ero candidates . the values of table 1 then point to higher surface densities than the values obtained by thompson et al . ( 1999 ) , which were based on an @xmath33 color and a survey area of 0.04 square degrees . in recent years it became clear that an early type population in clusters was well in place at redshifts of at least 0.8 ( e.g. stanford , eisenhardt , & dickinson 1998 ) . thus we may hope to detect these clusters by looking for overdensities of red objects with colors resembling the color sequence of cluster early - type galaxies . the surface density field is divided into ( overlapping ) slices in @xmath24 color . these slices are then smoothed by a kernel of the angular size of a cluster core at the apropriate redshift for that particular color range . cluster candidates are identified as overdensities in this data cube . figure 3 shows the redshift distribution for objects in the vicinity of a high redshift cluster candidate detected in this fashion as a demonstration of the efficiency of the technique . the cluster candidate is first detected as an overdensity of red objects in @xmath24 . then this detection is verified by looking at the histogram of photometric redshifts in the vicinity of the cluster candidate . bahcall , n. a. , fan , x. , & cen , r. 1997 , , 485 , l53 barger , a.j . , et al . 1999 , , 117 , 102 benitez , n. , et al . 1999 , , 515 , 65l broadhurst , t. , & bouwens , r. j. 1999 , astro - ph/9903009 bruzual , g. , & charlot , s. 2000 , in preparation eke , v. r. , cole , s. , & frenk , c. s. 1996 , , 282 , 263 fan , x. , bahcall , n. a. , & cen , r. 1997 , , 490 , l123 franceschini , a. , et al . 1998 , , 506 , 600 jimenez , r. , et al . 1999 , , 305 , 16 kauffmann , g. , & charlot , s. 1998 , , 297 , l23 cole , s. , et al . 1994 , , 271 , 781 shade , d. , et al . 1999 , astro - ph/9906171 spinrad , h. , et al . 1997 , , 484 , 581 stanford , s.a . , eisenhardt , p.r . , & dickinson , m. 1998 , , 492 , 461 thompson , d. , et al . 1999 , , 523 , 100 totani , t. , & yoshii , y. 1998 , , 501 , l177

the munich near - ir cluster survey ( munics ) is a @xmath0 selected survey covering 1 square degree in the @xmath0 and @xmath1 nir bands with complementary optical photometry in the @xmath2 , @xmath3 , and @xmath4 bands covering a subarea of 0.35 square degrees . the @xmath5 limiting magnitude is 19.5 in @xmath0 . the main goals of the project are the identification of clusters of galaxies at redshifts @xmath6 and the study of the evolution of the early - type field population at similar redshifts . here we present first results regarding color distributions and the surface densities of eros as well as photometric redshifts and a first clustering analysis of the sample .

jk was born in 1934 in a family of agriculturalists in cuddalore in tamil nadu . he grew up under the aegis of an uncle who introduced him to the works of subramanya bharathi and communist ideologies . jk has written more than 200 short stories , 40 novelettes , 15 novels , 500 essays , and 3 biographies . one of his novels unnaippol oruvan taken as a movie became the 1 tamil film to get the president 's award ( 3 prize ) in the best regional film category . he has received many awards , such as the rajarajan award , bharathya baksha parikshit award , nehru literary award given by the union of soviet socialist republics . the most notable awards are padma bhushan , the jnanpith award , fellow of sahitya akademi and sahitya akademi translation prize for his novel sila nerangalil sila manithargal . he is very much interested in highlighting the lives and thoughts of the under - privileged and the marginalized . in his own words he says , there was a time when numbered amongst my close friends were rickshaw drivers , prostitutes , rowdies , pickpockets , and cigarette - butt scavengers . perhaps because of this fact i can never work up disgust towards their kind . sometimes i even wonder whether i would nt have been happier if i had decided to live among them as one of the families . there is in the life of such people a flaming passion , a liveliness and truth . they hold a notion that i have all along been writing about people of the lower strata . however , havent i really been writing high level people among the so - called lower strata . who belongs to the higher strata and whom to the lower strata ? that can not be determined by their position or by their place of living it is how they are - how they live - that a determination should be made . k. diraviam , tamil scholar and former chief secretary to the tamil nadu government , has written in appreciation of jk , jk is a phenomenon in contemporary tamil writing an inspiration to some , a challenge to some , an anathema to a few . there are also some who consider him a disturbing element , with his alleged obsession with individual perversions and social aberrations . however , whether he pleases or provokes delights or disturbs , soothes or sears , consoles or challenges , none can deny that he is a writer of rare power and refreshing realism , vigorous in his portrayal , virile in his style , sweeping in his range and subtle in his touches . ( from his book confined out in the open ) jk visits an institution for the mentally ill and gets acquainted with four of the inmates . one of them is a highly qualified , foreign - trained , professor of physics who develops schizophrenic breakdown after his return to india . the response to electro convulsive treatment and insulin coma treatment ( both out of vogue now ) had been poor and he was leucotomised . the 2 patient suffered from repeated epileptic attacks in his youth and later developed delusional disorder . the 3 subject , a rich farmer fallen on evil days developed severe depressive disorder and committed multiple , motiveless murders with amnesia for his actions . the next subject was a responsible civil servant who had developed delusions that he was lord rama and his wife was sita and his brother lakshman . the descriptions include those of a paranoid personality , a dependent personality and a few others suffering from personality disorders not otherwise specified . jk 's descriptions appeared in book form in the late 1960 's and the following excerpts are from his introductions . his enlightened views on the subject of mental illness and its treatment could be found in the following passages ( translated ) . even after a mentally ill person is completely cured , this world suspects him ; ridicules him ; is afraid of being alone with him . even his wife is afraid of remaining alone with him in a room . by these activities this world sends him back to the asylum . there i met some people who underwent such treatment in the hands of this world . like the world is afraid of them , they are also afraid of this world . is not this world bigger than their world ? that 's why they forget you and me the people of the outer world ; and act . they cry , laugh , sing , dance , speak , love , and show gratitude . some time ago when you were dressing in your private room , you were nude a thin screen draws a line between you and them . the other day in uncontrollable anger you threw a vessel and broke it that sometimes in solitude , in a similar state of happiness they talk to themselves . but they are insane ! because of happiness or sorrow beyond limits , have you not spent sleepless nights ? only this occasionally and always have created such a great difference there are people who do not cross the border of insanity who stand within the border and often touch the border and return and who touch the border and do not return . we call many of our insanities desire , affection , devotion , love , art , valour and entertainment and are happy with ourselves . if we deeply think about them with a clear mind we can understand that we are all mad ; madness alone is human nature . we say that if a man laughs and weeps with the reason he is not mad , and if a man laughs and weeps without reason ( as far as we know ) he is mad . in the past when we laughed and cried we gave reasons to justify our actions . i am telling this just to insist that it is not proper to shun the mentally ill thinking that they have nothing to do with us or they are fit only for our ridicule and ill treatment . the basic similarity between us and them is they do not know that they are insane and we do not know to what degree we are mad . so knowing the degrees of our madness is the criterion for our mental health . mind is more complicated than the physical body . an artist who just draws all the faces that make up his picture is not skilful . his skill is judged by his ability to draw various expressions , figures , scenes , etc . , we should be impressed by the way the great artist called nature has created each human being in a different design . how many different types of men ! how many different shades in eyes alone ! in nose profiles , in complexion , in hair curls , in throwing - up arms , in gait , in tone , in sound . if the universe can be divided into innumerable tiny divisions how many divisions can we make that many ! the ability to perceive all these is artistic attainment . if in outward appearance alone there are so many divisions how many there will be in mind , thinking , ideas , fear , desires , appreciation in all these inward happenings ! there is no justification in it to fear , to make them all alike , to feel bored , to be worried for these opposites among men . only these move human life . if these do not exist there will be no art , no literature , no imagination , in short , no individual . however , you are or you think you are you approach them accepting them as they are . in another of his remarkable novels , rishi moolam which when translated into english means the origins of a recluse , jk gives a vivid description of the onset and progress of schizophrenic disorder in a young man named rajaraman . hailing from krishnagiri , a village situated on the banks of river cauvery , rajaraman is presented as a recluse . rajaraman is the 2 son of krishna iyer , who is an expert in rituals and vedantic knowledge . after his schooling , he goes to annamalai university and resides at the house of sambaiyer , who runs a hotel . no grown up child was allowed inside that room . 1 day , with childish curiosity rajaraman entered the room . when his mother walked in after her bath , he hid under a cot and without intending to , witnessed her nudity . this incident left a deep scar in his subconscious mind , as a result of which he experienced depression and had disturbing dreams . after a few years his sister and her husband see him in the town of varanasi and bring him home . he is given a thatched outhouse where he spends all his time in solitude , laying down on the ground , smoking tobacco , and cannabis and gazing at the other bank of cauvery where corpses are cremated . with every cremation , he imagines that he too is being cremated . this way he tries to obliterate his ego . this story is reminiscent of the so called clinical biographies of chronic schizophrenic patients and their extended families presented by laing in his books , the divided self and sanity , madness and family . although , vulnerability - stress causation is given importance currently , the works of jk and laing were published in the 1960 's and 1970 's when the importance of the schizophrenogenic family ( rather than schizophrenogenic mother ) was emphasized . burgeoning radio imaging and molecular genetics later shifted the scales in favor of biological factors . nevertheless , psychological and social factors are still considered important in the onset and relapse of schizophrenia ( for details refer to the bio - psychosocial model of schizophrenia and a cognitive model of schizophrenia ) . much of the incomprehensible speech and odd behaviour of these patients could be understood if the environment of the patient is analysed properly . in the words of laing the patient many of the concepts of the disorder touched upon by jk could be utilized in the psycho education and family intervention therapies , incidentally contributing to anti - stigma measures and compliance therapy . in passing , his descriptions of the self are very close to the existential theories of heidegger and sartre . in another remarkable novel entitled a man , a home and a world published in 1971 , jk describes an non resident indian from erstwhile burma returning for the 1 time to his father 's village at the foothills of a mountain range in tamil nadu . travelling in a lorry the lorry driver informs henry that she is a harmless , homeless , wandering lunatic of the place , causing no harm to the locals and benevolently ignored by the neighbours . henry 's next encounter with her is when he sees her stark naked , sitting on a pile of bricks with her knees drawn towards her . henry is informed that though villagers have offered dress materials to her , she does not use them . when henry re - builds his father 's ancestral cottage , he offers her a wooden plank to lie upon and tells her in english to wear the dress he is offering her . she then regularly visits the building site and watches the masons at work . when one of them asks her water to drink , henry tells her to help him . she pours the water in a glass and offers to the needy . her service is also utilized to quench the thirst of school going children . she is slowly socialized and now she starts wearing clothes . the villagers know that she is not deaf and somehow understands instructions given in english through gestures . henry succeeds in breaking up her social withdrawal and isolation and builds up an interpersonal relationship between her and the neighbours . during the housewarming ceremony attended by a number of local residents the girl participates in the various activities . after some time , to the great surprise of others and to the disappointment of henry , she disappears from the scene , leaving her dress material behind . it can only be presumed that the social stimulations were too much for her and had precipitated her relapse . we can be sure that henry would try again to bring about a happy ending . jk succeeds remarkably well in depicting the existence of a chronic , wandering , mentally ill subject in a rural setting where little stigma is shown to the sufferers of mental illness . the attempt and success of henry in rehabilitating this girl ( though with temporary relief ) brings to our mind the foster family care practised in geel at belgium . geel is well known for the early adoption of de - institutionalization in psychiatric care . this practice is based on the positive effects that placement in a host family gives the patient , most importantly , access to family life that would otherwise have been denied . goldstein , in his internet article titled geel , belgium : a model of community recovery writes , for the individual with mental illness striving to live a meaningful life in the context of the recovery model of treatment , ( compare to medical model with a goal of symptom reduction and/or cure ) opportunities for community integration serve that model and are critical to its success . successful recovery for individuals , in turn , allows them greater ability to function as members of their community . thus , it is logical to encourage a concept of community recovery in which communities strive to live with , rather than fear , the realities of mental illness . presently , psychosocial treatment for the severely mentally ill jk is familiar with the use of alcohol , nicotine and ganja and is frank enough to share his experiences in many of his writings ( but aware of their limits and limitations ) . many of his characters including women are habituated to drinks and end up in ruins . he is very definite that legal restrictions should not be placed on their use and does not approve of the state 's prohibition politics . he stresses the individual 's rights to drink and enjoy ( i am not quite sure whether he would preach temperance along with thiruvalluvar ! ) . one of the characters in his novel one man , one home and one world under the influence of ganjahallucinates a lamp is burning inside a temple . a floor made of red tiles at the sanctum sanctorum . shiva 's temple the grass growing in the cracks between the tiles form green squares . the lamp is burning inside a small lamp no deity . only a lamp an earthen lamp . the flame is motionless . now in the sanctum sanctorum one can hear a musical sound . do nt know if it is a child or a woman . between the tiles there are green lines made of grass , on the tile the child 's feet the lamp is burning inside . the lamp is lit with the water there is fire but no heat it is cool a lamp lit with water . the reader of this passage could immediately recall to his mind , the earlier description of aldous huxley 's experience with mexican cactus peyote , whose ingredient is mescaline . another character in jk 's novel decries the cruel treatment meted out by the police to the prohibition law breakers . ( from his book confined out in the open ) jk visits an institution for the mentally ill and gets acquainted with four of the inmates . one of them is a highly qualified , foreign - trained , professor of physics who develops schizophrenic breakdown after his return to india . the response to electro convulsive treatment and insulin coma treatment ( both out of vogue now ) had been poor and he was leucotomised . the 2 patient suffered from repeated epileptic attacks in his youth and later developed delusional disorder . the 3 subject , a rich farmer fallen on evil days developed severe depressive disorder and committed multiple , motiveless murders with amnesia for his actions . the next subject was a responsible civil servant who had developed delusions that he was lord rama and his wife was sita and his brother lakshman . the descriptions include those of a paranoid personality , a dependent personality and a few others suffering from personality disorders not otherwise specified . jk 's descriptions appeared in book form in the late 1960 's and the following excerpts are from his introductions . his enlightened views on the subject of mental illness and its treatment could be found in the following passages ( translated ) . even after a mentally ill person is completely cured , this world suspects him ; ridicules him ; is afraid of being alone with him . even his wife is afraid of remaining alone with him in a room . by these activities this world sends him back to the asylum . there i met some people who underwent such treatment in the hands of this world . like the world is afraid of them , they are also afraid of this world . is not this world bigger than their world ? that 's why they forget you and me the people of the outer world ; and act . they cry , laugh , sing , dance , speak , love , and show gratitude . some time ago when you were dressing in your private room , you were nude a thin screen draws a line between you and them . the other day in uncontrollable anger you threw a vessel and broke it that sometimes in solitude , in a similar state of happiness they talk to themselves . but they are insane ! because of happiness or sorrow beyond limits , have you not spent sleepless nights ? they also have been like that . only this occasionally and always have created such a great difference there are people who do not cross the border of insanity who stand within the border and often touch the border and return and who touch the border and do not return . consider seriously , who is not insane among us ? we call many of our insanities desire , affection , devotion , love , art , valour and entertainment and are happy with ourselves . if we deeply think about them with a clear mind we can understand that we are all mad ; madness alone is human nature . we say that if a man laughs and weeps with the reason he is not mad , and if a man laughs and weeps without reason ( as far as we know ) he is mad . in the past when we laughed and cried we gave reasons to justify our actions . i am telling this just to insist that it is not proper to shun the mentally ill thinking that they have nothing to do with us or they are fit only for our ridicule and ill treatment . the basic similarity between us and them is they do not know that they are insane and we do not know to what degree we are mad . so knowing the degrees of our madness is the criterion for our mental health . an artist who just draws all the faces that make up his picture is not skilful . his skill is judged by his ability to draw various expressions , figures , scenes , etc . , we should be impressed by the way the great artist called nature has created each human being in a different design . how many different types of men ! how many different shades in eyes alone ! in nose profiles , in complexion , in hair curls , in throwing - up arms , in gait , in tone , in sound . if the universe can be divided into innumerable tiny divisions how many divisions can we make that many ! the ability to perceive all these is artistic attainment . if in outward appearance alone there are so many divisions how many there will be in mind , thinking , ideas , fear , desires , appreciation in all these inward happenings ! there is no justification in it to fear , to make them all alike , to feel bored , to be worried for these opposites among men . only these move human life . if these do not exist there will be no art , no literature , no imagination , in short , no individual . however , you are or you think you are you approach them accepting them as they are . in another of his remarkable novels , rishi moolam which when translated into english means the origins of a recluse , jk gives a vivid description of the onset and progress of schizophrenic disorder in a young man named rajaraman . hailing from krishnagiri , a village situated on the banks of river cauvery , rajaraman is presented as a recluse . rajaraman is the 2 son of krishna iyer , who is an expert in rituals and vedantic knowledge . after his schooling , he goes to annamalai university and resides at the house of sambaiyer , who runs a hotel . no grown up child was allowed inside that room . 1 day , with childish curiosity rajaraman entered the room . when his mother walked in after her bath , he hid under a cot and without intending to , witnessed her nudity . this incident left a deep scar in his subconscious mind , as a result of which he experienced depression and had disturbing dreams . after a few years his sister and her husband see him in the town of varanasi and bring him home . he is given a thatched outhouse where he spends all his time in solitude , laying down on the ground , smoking tobacco , and cannabis and gazing at the other bank of cauvery where corpses are cremated . with every cremation , he imagines that he too is being cremated . this way he tries to obliterate his ego . this story is reminiscent of the so called clinical biographies of chronic schizophrenic patients and their extended families presented by laing in his books , the divided self and sanity , madness and family . although , vulnerability - stress causation is given importance currently , the works of jk and laing were published in the 1960 's and 1970 's when the importance of the schizophrenogenic family ( rather than schizophrenogenic mother ) was emphasized . burgeoning radio imaging and molecular genetics later shifted the scales in favor of biological factors . nevertheless , psychological and social factors are still considered important in the onset and relapse of schizophrenia ( for details refer to the bio - psychosocial model of schizophrenia and a cognitive model of schizophrenia ) . much of the incomprehensible speech and odd behaviour of these patients could be understood if the environment of the patient is analysed properly . in the words of laing the patient many of the concepts of the disorder touched upon by jk could be utilized in the psycho education and family intervention therapies , incidentally contributing to anti - stigma measures and compliance therapy . in passing , his descriptions of the self are very close to the existential theories of heidegger and sartre . in another remarkable novel entitled a man , a home and a world published in 1971 , jk describes an non resident indian from erstwhile burma returning for the 1 time to his father 's village at the foothills of a mountain range in tamil nadu . travelling in a lorry the lorry driver informs henry that she is a harmless , homeless , wandering lunatic of the place , causing no harm to the locals and benevolently ignored by the neighbours . henry 's next encounter with her is when he sees her stark naked , sitting on a pile of bricks with her knees drawn towards her . henry is informed that though villagers have offered dress materials to her , she does not use them . when henry re - builds his father 's ancestral cottage , he offers her a wooden plank to lie upon and tells her in english to wear the dress he is offering her . she then regularly visits the building site and watches the masons at work . when one of them asks her water to drink , henry tells her to help him . she pours the water in a glass and offers to the needy . her service is also utilized to quench the thirst of school going children . she is slowly socialized and now she starts wearing clothes . the villagers know that she is not deaf and somehow understands instructions given in english through gestures . henry succeeds in breaking up her social withdrawal and isolation and builds up an interpersonal relationship between her and the neighbours . during the housewarming ceremony attended by a number of local residents the girl participates in the various activities . after some time , to the great surprise of others and to the disappointment of henry , she disappears from the scene , leaving her dress material behind . it can only be presumed that the social stimulations were too much for her and had precipitated her relapse . we can be sure that henry would try again to bring about a happy ending . jk succeeds remarkably well in depicting the existence of a chronic , wandering , mentally ill subject in a rural setting where little stigma is shown to the sufferers of mental illness . the attempt and success of henry in rehabilitating this girl ( though with temporary relief ) brings to our mind the foster family care practised in geel at belgium . geel is well known for the early adoption of de - institutionalization in psychiatric care . this practice is based on the positive effects that placement in a host family gives the patient , most importantly , access to family life that would otherwise have been denied . goldstein , in his internet article titled geel , belgium : a model of community recovery writes , for the individual with mental illness striving to live a meaningful life in the context of the recovery model of treatment , ( compare to medical model with a goal of symptom reduction and/or cure ) opportunities for community integration serve that model and are critical to its success . successful recovery for individuals , in turn , allows them greater ability to function as members of their community . thus , it is logical to encourage a concept of community recovery in which communities strive to live with , rather than fear , the realities of mental illness . presently , psychosocial treatment for the severely mentally ill jk is familiar with the use of alcohol , nicotine and ganja and is frank enough to share his experiences in many of his writings ( but aware of their limits and limitations ) . many of his characters including women are habituated to drinks and end up in ruins . he is very definite that legal restrictions should not be placed on their use and does not approve of the state 's prohibition politics . he stresses the individual 's rights to drink and enjoy ( i am not quite sure whether he would preach temperance along with thiruvalluvar ! ) . one of the characters in his novel one man , one home and one world under the influence of ganjahallucinates a lamp is burning inside a temple . a floor made of red tiles at the sanctum sanctorum . shiva 's temple the grass growing in the cracks between the tiles form green squares . the lamp is burning inside a small lamp no deity . only a lamp an earthen lamp . the flame is motionless . now in the sanctum sanctorum one can hear a musical sound . do nt know if it is a child or a woman . between the tiles there are green lines made of grass , on the tile the child 's feet the lamp is burning inside . the lamp is lit with the water there is fire but no heat it is cool a lamp lit with water . the reader of this passage could immediately recall to his mind , the earlier description of aldous huxley 's experience with mexican cactus peyote , whose ingredient is mescaline . another character in jk 's novel decries the cruel treatment meted out by the police to the prohibition law breakers . anti - stigma measures should take the help of literary works of writers enlightened in this area , like jk dealt with in this write up . it is suggested that the local psychiatric societies should periodically select works of this nature and popularise them through media . we can have discussion groups of professionals , journalists and lay public through visual and auditory media . is actually increasing negative aspects of mental illness which can be counteracted by the above mentioned suggestions .

national and international associations of psychiatry are busy formulating and executing anti - stigma measures and activities . literary works of creative artists could be utilised for this purpose . this article based on the writings of a popular tamil writer jayakanthan discusses some of his works in relation to this .

Former schoolteacher Mary Kay Letourneau and husband Vili Fualaau, with whom she began a sexual relationship when he was her sixth-grade student in Seattle in 1996, have legally separated and a reconciliation seems unlikely, PEOPLE confirms. “They’ve been having issues for a while now,” says a source close to the couple. “They tried to work through them, but it didn’t work. They’re still committed to being good parents to their children.” There is no third party involved in the relationship, the source says. Letourneau’s friend and former attorney David Gehrke says it was Fualaau who filed for separation. “She could try to contest it, but that’s legally tough to do,” he says. “Perhaps if they want to figure out about the children and child support, but their kids are getting pretty old now.” “When one person is unhappy in the relationship, the other person can’t be happy either,” he continues. “And there are two people in this relationship.” Their initial affair — which began while Letourneau was a 34-year-old mother of four and Fualaau was 12 — ignited national controversy and revulsion, particularly after she defied a court order to stay away from Fualaau. “The two of them want to be together,” a friend of Letourneau’s told PEOPLE in a 1998 cover story. “They’re drawn together like magnets.” Prosecutors took a different view, arguing at the time that Letourneau “doesn’t believe she did anything wrong.” After the relationship was revealed, she pleaded guilty to two counts of second-degree child rape and was sentenced to seven and a half years in prison. She and Fualaau married in May 2005 after she was released, and they have two children. “I’m convinced they were totally in love,” Gehrke says. Mary Kay Letourneau in 1996 AP Photo/Seattle Post-Intelligencer Mary Kay Letourneau in court in Seattle in February 1998 Alan Berner/AP A March 1998 PEOPLE cover story on the Mary Kay Letourneau case The couple’s second child, Georgia, was born while Letourneau was behind bars. They sat down with PEOPLE for an extensive interview in 2006. Fualaau, then 22, said he sometimes wondered about the past. “I think, What would my life have been like if I had never made a move on Mary?” he said. “What if I had kept it as a crush and left it at that? Where would I be and where would she be — what would life be like?” But he said he didn’t see an answer to such speculation. “I can never see more than the question.” • Want to keep up with the latest crime coverage? Click here to get breaking crime news, ongoing trial coverage and details of intriguing unsolved cases in the True Crime Newsletter. Vili Fualaau in October 1998 John Froschauer/AP Vili Fualaau and Mary Kay Letourneau (center left and center right) with their two daughters, Audrey (far left) and Georgia (far right), in 2015 Heidi Gutman/ABC/Getty Nearly a decade later, in 2015, Fualaau and Letourneau sat down for an interview with ABC’s Barbara Walters, where they discussed their relationship, marriage and parenting. Letourneau revealed then that she would like to get her name taken off the sex offender registry, though officials in Washington state tell PEOPLE she is still a registered offender. “There is a story of us that has a life of its own, but it’s not our story,” she told Walters. When Walters asked Fualaau how he’d feel if the girls came home and said they were sleeping with their teacher, he responded, “I don’t support younger kids being married or having a relationship with someone older. I don’t support it.” • With K.C. BLUMM and ALEX TRESNIOWSKI ||||| Vili Fualaau, 33, filed for legal separation from Mary Kay Letourneau, 55, earlier this month, according to court documents. The couple have been married since 2005. Vili Fualaau has filed for legal separation from Mary Kay Letourneau, the former Highline teacher who was jailed for having sex with him beginning when he was in sixth grade. Fualaau, 33, filed for the legal separation from Letourneau, 55, earlier this month, according to King County Superior Court documents. The couple have been married since 2005. Their separation was first reported Tuesday afternoon by TMZ. The two met when he was in the second grade and she was a teacher at Shorewood Elementary School in Burien. Their relationship became sexual when he was 12 and she was 34 and a married mother of four. She was arrested in 1997 after she became pregnant with his child, and was convicted of second-degree child rape. She was paroled after six months but was again caught having sex with Fualaau, a violation of her parole conditions. She gave birth to the couple’s second child in prison while serving the remainder of her 7½-year sentence. She was released in 2004 and the couple married in a ceremony in Woodinville the next year. Their relationship sparked national attention and was chronicled in the Lifetime movie “Mary Kay Letourneau: All American Girl.” The two, with their two daughters, were interviewed by Barbara Walters in 2015. The couple and their two daughters have remained in the region, with their last address listed in Des Moines. Starting in 2009, the two hosted “Hot for Teacher” nights at a Seattle nightclub.

– Mary Kay Letourneau and Vili Fualaau are separating after 12 years of marriage—and 20 years after Letourneau was arrested for having sex with her then-12-year-old student. TMZ reports Fualaau filed for legal separation this month. An unnamed source tells People Letourneau, 55, and Fualaau, 33, have "been having issues for a while now" but are "still committed to being good parents to their children." Letourneau's attorney says the two "were totally in love," but "when one person is unhappy in the relationship, the other person can’t be happy either." The couple had been hosting "Hot for Teacher" nights together at a Seattle nightclub, the Seattle Times reports. Letourneau first met Fualaau when he was in second grade. They started a sexual relationship in 1996 when Fualaau was in sixth grade and Letourneau was 34. Letourneau was arrested in 1997 after getting pregnant with Fualaau's child. She was sentenced to more than seven years in prison for second-degree child rape. She gave birth to their second child while still behind bars. Letourneau was released in 2004 and married Fualaau in 2005. She remains a registered sex offender.

in this work we are interested by the asymptotic study of non - regular parametric statistical models encountered in statistical inference for stochastic processes . an exhaustive exposition of the parameter estimation theory in both regular and non - regular cases is given in the classical book @xcite by ibragimov and khasminskii . they have developed a general theory of estimation based on the analysis of renormalized likelihood ratio . their approach consists in proving first that the renormalized likelihood ratio ( with a properly chosen renormalization rate ) weekly converges to some non - degenerate limit : the limiting likelihood ratio process . thereafter , the properties of the estimators ( namely their rate of convergence and limiting distributions ) are deduced . finally , based on the estimators , one can also construct confidence intervals , tests , and so on . note that this approach also provides the convergence of moments , allowing one to deduce equally the asymptotics of some statistically important quantities , such as the mean squared errors of the estimators . it is well known that in the regular case the limiting likelihood ratio is given by the lan property and is the same for different models ( the renormalization rate being usually @xmath0 ) . so , the classical estimators the maximum likelihood estimator and the bayesian estimators are consistent , asymptotically normal ( usually with rate @xmath0 ) and asymptotically efficient . in non - regular cases the situation essentially changes : the renormalization rate is usually better ( for example , @xmath1 in change - point type models ) , but the limiting likelihood ratio can be different in different models . so , the classical estimators are still consistent , but may have different limiting distributions ( though with a better rate ) and , in general , only the bayesian estimators are asymptotically efficient . in @xcite a relation between two different limiting likelihood ratios arising in change - point type models was established by one of the authors . more precisely , it was shown that the first one , which is an exponential functional of a two - sided poisson process driven by some parameter , can be approximated ( for sufficiently small values of the parameter ) by the second one , defined by @xmath2 where @xmath3 is a standard two - sided brownian motion . in this paper we consider yet another limiting likelihood ratio process arising in change - point type models and show that it is related to @xmath4 in a similar way . we introduce the random process @xmath5 on @xmath6 as the exponent of a two - sided compound poisson process given by @xmath7 where @xmath8 , @xmath9 is a strictly positive density of some random variable @xmath10 with mean @xmath11 and variance @xmath12 , @xmath13 and @xmath14 are two independent poisson processes of intensity @xmath12 on @xmath15 , @xmath16 are independent random variables with density @xmath9 which are also independent of @xmath17 , and we use the convention @xmath18 . we equally introduce the random variables @xmath19 , \end{aligned } \ ] ] related to this process , as well as their second moments @xmath20 and @xmath21 . an important particular case of this process is the one where the density @xmath9 is gaussian , that is , @xmath22 . in this case we will omit the index @xmath9 and write @xmath23 instead of @xmath5 , @xmath24 instead of @xmath25 , and so on . note that since @xmath26 the process @xmath23 is symmetric and has gaussian jumps . the process @xmath5 , up to a linear time change , arises in some non - regular , namely change - point type , statistical models as the limiting likelihood ratio process , and the variables @xmath27 and @xmath25 as the limiting distributions of the bayesian estimators and of the appropriately chosen maximum likelihood estimator , respectively . the maximum likelihood estimator being not unique in the underlying models , the appropriate choice here is a linear combination with weights @xmath28 and @xmath29 of its minimal and maximal values . moreover , the quantities @xmath30 and @xmath31 are the limiting mean squared errors ( sometimes also called limiting variances ) of these estimators and , the bayesian estimators being asymptotically efficient , the ratio @xmath32 is the asymptotic relative efficiency of this maximum likelihood estimator . the examples include the two - phase regression model and the threshold autoregressive ( tar ) model . the linear case of the former was studied by koul and qian in @xcite , while the non - linear one was investigated by ciuperca in @xcite . concerning the tar model , the first results were obtained by k.s . chan in @xcite , while a more recent study was performed by n.h . chan and kutoyants in @xcite . note however , that the estimator studied in @xcite is the least squares estimator ( which is , in the gaussian case , equivalent to the maximum likelihood estimator ) , while the model considered in @xcite is the gaussian tar model . so , only the processes @xmath23 are known to arise as limiting likelihood ratios in the tar model . note also that in both models , the parameter @xmath33 of the limiting likelihood ratio is related to the jump size of the model . on the other hand , many change - point type statistical models encountered in various fields of statistical inference for stochastic processes rather have as limiting likelihood ratio process , up to a linear time change , the process @xmath4 defined by . in this case , the limiting distributions of the bayesian estimators and of the maximum likelihood estimator are given by @xmath34 respectively , while the limiting mean squared errors of these estimators are @xmath35 and @xmath36 . the bayesian estimators are still asymptotically efficient , and the asymptotic relative efficiency of the maximum likelihood estimator is @xmath37 . a well - known example is the model of a discontinuous signal in a white gaussian noise exhaustively studied by ibragimov and khasminskii in @xcite and ( * ? ? ? * chapter 7.2 ) , but one can also cite change - point type models of dynamical systems with small noise considered by kutoyants in @xcite and ( * ? ? ? * chapter 5 ) , those of ergodic diffusion processes examined by kutoyants in ( * ? ? ? * chapter 3 ) , a change - point type model of delay equations analyzed by kchler and kutoyants in @xcite , a model of a discontinuous periodic signal in a time inhomogeneous diffusion investigated by hpfner and kutoyants in @xcite , and so on . let us also note that terentyev in @xcite determined the laplace transform of @xmath38 and calculated the constant @xmath39 . moreover , the explicit expression of the density of @xmath40 was later successively provided by bhattacharya and brockwell in @xcite , by yao in @xcite and by fujii in @xcite . regarding the constant @xmath41 , ibragimov and khasminskii in ( * ? ? ? * chapter 7.3 ) showed by means of numerical simulation that @xmath42 , and so @xmath43 . later in @xcite , golubev expressed @xmath41 in terms of the second derivative ( with respect to a parameter ) of an improper integral of a composite function of modified hankel and bessel functions . finally in @xcite , rubin and song obtained the exact values @xmath44 and @xmath45 , where @xmath46 is riemann s zeta function defined by @xmath47 . in this paper we establish that the limiting likelihood ratio processes @xmath5 and @xmath4 are related . more precisely , under some regularity assumptions on @xmath9 , we show that as @xmath48 , the process @xmath49 , @xmath50 , ( where @xmath51 is the fisher information related to @xmath9 ) converges weakly in the space @xmath52 ( the skorohod space of functions on @xmath6 without discontinuities of the second kind and vanishing at infinity ) to the process @xmath4 . hence , the random variables @xmath53 and @xmath54 converge weakly to the random variables @xmath55 and @xmath40 , respectively . we show equally that the convergence of moments of these random variables holds and so , in particular , @xmath56 , @xmath57 and @xmath58 . besides their theoretical interest , these results have also some practical implications . for example , they allow to construct tests and confidence intervals on the base of the distributions of @xmath55 and @xmath40 ( rather than on the base of those of @xmath27 and @xmath25 , which depend on the density @xmath9 and are not known explicitly ) in models having the process @xmath5 with a small @xmath33 as a limiting likelihood ratio . also , the limiting mean squared errors of the estimators and the asymptotic relative efficiency of the maximum likelihood estimator can be approximated as @xmath59 in such models . these are the main results of the present paper , and they are presented in section [ mr ] , where we also briefly discuss the second possible asymptotics @xmath60 and present some numerical simulations of the quantities @xmath61 , @xmath62 and @xmath63 for @xmath640,\infty\right[$ ] . finally , the proofs of the necessary lemmas are carried out in section [ pl ] . concluding the introduction let us note that a preliminary exposition ( in the particular gaussian case ) of the results of the present paper can be found in @xcite and @xcite . let @xmath8 , and let @xmath9 be a strictly positive density of some random variable @xmath10 with mean @xmath11 and variance @xmath12 . we will always suppose that @xmath65 is continuously differentiable in @xmath66 , that is , there exists @xmath67 satisfying @xmath68 and @xmath69 , as well as that @xmath70 . note that under this assumptions , the model of i.i.d . observations with density @xmath71 is , in particular , lan at @xmath72 with fisher information @xmath73 @xmath74see , for example , ( * ? ? ? * chapter 2.1)@xmath75 and so , using characteristic functions , we have @xmath76 and , more generally , @xmath77 for all @xmath78 . note also , that only the convergence will be needed in our considerations . so , one can rather assume it directly , or make any other regularity assumptions sufficient for it as , for example , hjek s conditions : @xmath9 is differentiable and the fisher information @xmath79 is finite and strictly positive @xmath74see , for example , ( * ? ? ? * chapter 2.2)@xmath75 . note finally , that in the gaussian case the regularity assumptions clearly hold and we have @xmath80 . let us consider the process @xmath81 , @xmath50 , where @xmath5 is defined by . note that @xmath82 where the random variables @xmath27 and @xmath83 are defined by . remind also the process @xmath4 on @xmath6 defined by and the random variables @xmath55 and @xmath40 defined by . recall finally the quantities @xmath20 , @xmath21 , @xmath32 , as well as @xmath84 , @xmath85 and @xmath86 . now we can state the main result of the present paper . [ t1 ] the process @xmath87 converges weakly in the space @xmath88 to the process @xmath4 as @xmath89 . in particular , the random variable @xmath53 converges weakly to the random variable @xmath55 and , for any @xmath90 $ ] , the random variable @xmath54 converges weakly to the random variable @xmath40 . moreover , for any @xmath91 we have @xmath92 in particular , @xmath93 , @xmath94 and @xmath58 . the results concerning the random variable @xmath27 are direct consequence of ( * ? ? ? * theorem 1.10.2 ) and the following three lemmas . [ l1 ] the finite - dimensional distributions of the process @xmath87 converge to those of @xmath4 as @xmath89 . [ l2 ] for any @xmath95 we have @xmath96 for all sufficiently small @xmath33 and all @xmath97 . [ l3 ] for any @xmath98\,0\,{,}\;1/8\,\right[$ ] we have @xmath99 for all sufficiently small @xmath33 and all @xmath50 . note that these lemmas are not sufficient to establish the weak convergence of the process @xmath87 in the space @xmath88 and the results concerning the random variable @xmath25 . however , the increments of the process @xmath100 being independent , the convergence of its restrictions ( and hence of those of @xmath87 ) on finite intervals @xmath101\subset{\mathbb{r}}$ ] @xmath74that is , convergence in the skorohod space @xmath102 $ ] of functions on @xmath101 $ ] without discontinuities of the second kind@xmath75 follows from ( * ? ? ? * theorem 6.5.5 ) , lemma [ l1 ] and the following lemma . [ l4 ] for any @xmath103 we have @xmath104 now , theorem [ t1 ] follows from the following estimate on the tails of the process @xmath87 by standard argument @xmath74see , for example , @xcite@xmath75 . [ l5 ] for any @xmath105\,0\,{,}\;1/12\,\right[$ ] we have @xmath106 for all sufficiently small @xmath33 and all @xmath107 . the proofs of all these lemmas will be given in section [ pl ] . now let us discuss the second possible asymptotics @xmath60 . it can be shown that in this case , the process @xmath5 converges weakly in the space @xmath88 to the process @xmath108 , @xmath109 , where @xmath110 and @xmath111 are two independent exponential random variables with parameter @xmath12 . so , the random variables @xmath27 , @xmath112 , @xmath113 and @xmath25 converge weakly to the random variables @xmath114 respectively . it can be equally shown that , moreover , for any @xmath91 we have @xmath115 in particular , denoting @xmath116 , @xmath117 and @xmath118 , we finally have @xmath119 let us note that these convergences are natural , since the process @xmath120 can be considered as a particular case of the process @xmath5 with @xmath121 under natural conventions @xmath122 and @xmath123 . note also , that @xmath120 is the limiting likelihood ratio process in the problem of estimating the parameter @xmath124 by i.i.d . uniform observations on @xmath125 $ ] . so , in this problem , the variables @xmath126 and @xmath127 are the limiting distributions of the bayesian estimators and of the appropriately chosen maximum likelihood estimator , respectively , while @xmath128 and @xmath129 are the limiting mean squared errors of these estimators and , the bayesian estimators being asymptotically efficient , @xmath130 is the asymptotic relative efficiency of this maximum likelihood estimator . finally observe , that the formulae and clearly imply that in the latter problem ( as well as in any problem having @xmath120 as limiting likelihood ratio ) the best choice of the maximum likelihood estimator is @xmath131 , and that the so chosen maximum likelihood estimator is asymptotically efficient . this choice was also suggested for tar model ( which has limiting likelihood ratio @xmath23 ) by chan and kutoyants in @xcite . for large values of @xmath33 this suggestion is confirmed by our asymptotic results . however , we see that for small values of @xmath33 the choice of @xmath28 will not be so important , since the limits in theorem [ t1 ] do not depend on @xmath28 . here we present some numerical simulations ( in the gaussian case ) of the quantities @xmath61 , @xmath62 and @xmath63 for @xmath640,\infty\right[$ ] . besides giving approximate values of these quantities , the simulation results illustrate both the asymptotics @xmath132 with @xmath133 , @xmath39 and @xmath134 , and @xmath135 with @xmath136 , @xmath137 and @xmath138 . first , we simulate the events @xmath139 of the poisson process @xmath13 and the events @xmath140 of the poisson process @xmath14 @xmath74both of intensity @xmath141 , as well as the partial sums @xmath142 of the i.i.d . @xmath143 sequence @xmath144 and the partial sums @xmath145 of the i.i.d . @xmath143 sequence @xmath146 for convenience we also put @xmath147 . then we calculate @xmath148 where @xmath149 and we use the values @xmath150 , @xmath151 and @xmath11 for @xmath28 . note that in this gaussian case ( due to the symmetry of the process @xmath23 ) the random variable @xmath152 has the same law as the variable @xmath153 , that s why we use for @xmath28 only values less or equal than @xmath150 . finally , repeating these simulations @xmath154 times ( for each value of @xmath33 ) , we approximate @xmath155 and @xmath156 by the empirical second moments , and @xmath157 by their ratio . the results of the numerical simulations are presented in figures [ fig1][fig3 ] . the @xmath48 asymptotics of the limiting mean squared errors is illustrated in figure [ fig1 ] , where we rather plotted the functions @xmath158 and @xmath159 , making apparent the constants @xmath160 and @xmath39 . one can observe here that the choice @xmath131 is the best one , though its advantage diminishes as @xmath33 approaches @xmath11 and seems negligible for @xmath161 . and @xmath162 ( @xmath48 asymptotics),scaledwidth=60.0% ] in figure [ fig2 ] we illustrate the @xmath163 asymptotics of the limiting mean squared errors by plotting the functions @xmath61 and @xmath62 themselves . here the advantage of the choice @xmath131 is obvious , and one can observe that for @xmath164 this choice makes negligible the loss of efficiency resulting from the use of the maximum likelihood estimator instead of the asymptotically efficient bayesian estimators . and @xmath62 ( @xmath163 asymptotics),scaledwidth=60.0% ] finally , in figure [ fig3 ] we illustrate the behavior both at @xmath11 and at @xmath165 of the asymptotic relative efficiency of the maximum likelihood estimators by plotting the functions @xmath63 . all the observations made above can be once more noticed in this figure . note also that as @xmath33 increases from @xmath11 to @xmath165 , the asymptotic relative efficiency seems first to decrease from @xmath166 for all the maximum likelihood estimators , before increasing back to @xmath130 for the maximum likelihood estimators with @xmath28 close to the optimal value @xmath150 . ( both asymptotics),scaledwidth=60.0% ] for the sake of clarity , for each lemma we will first give the proof in the particular gaussian case ( in which it is more explicit ) and then explain how it can be extended to the general one . note that the restrictions of the process @xmath167 , @xmath50 , ( as well as those of the process @xmath168 ) on @xmath15 and on @xmath169 are mutually independent processes with stationary and independent increments . so , to obtain the convergence of all the finite - dimensional distributions , it is sufficient to show the convergence of one - dimensional distributions only , that is , the weak convergence of @xmath170 to @xmath171 for all @xmath50 . moreover , these processes being symmetric , it is sufficient to consider @xmath172 only . the characteristic function @xmath173 of @xmath174 is @xmath175 where we have denoted @xmath176 the @xmath177-algebra related to the poisson process @xmath13 , used the independence of @xmath178 and @xmath13 and recalled that @xmath179 . then , noting that @xmath180 is a poisson random variable of parameter @xmath181 with moment generating function @xmath182 , we get @xmath183 as @xmath184 and so , in the gaussian case lemma [ l1 ] is proved . the process @xmath191 being symmetric , we have @xmath192 for all @xmath50 and , since @xmath193 as @xmath184 , for any @xmath98\,0\,{,}\;1/8\,\right[$ ] we have @xmath194 for all sufficiently small @xmath33 and all @xmath50 . so , in the gaussian case lemma [ l3 ] is proved . in the general case , equality becomes @xmath195 with @xmath196 recall the convergence of characteristic functions and note that @xmath197 are the corresponding moment generating functions at point @xmath150 . the convergence of these moment generating functions ( at any point smaller than @xmath12 ) follows from the fact that for all @xmath33 they are equal @xmath12 at point @xmath12 ( which provides uniform integrability ) . thus we have @xmath198 , which implies @xmath199 , and so @xmath200 . first we consider the case @xmath201 ( say @xmath202 ) . using and taking into account the stationarity and the independence of the increments of the process @xmath203 on @xmath15 , we can write @xmath204 first let @xmath201 ( say @xmath202 ) such that @xmath211 . then , noting that conditionally to @xmath176 the random variable @xmath212 is gaussian with mean @xmath213 and variance @xmath214 , we get @xmath215 where @xmath216 as @xmath48 . so , we have @xmath217 and hence @xmath218 where the supremum is taken only over @xmath201 . finally , for @xmath206 ( say @xmath207 ) such that @xmath219 , using the elementary inequality @xmath220 we get @xmath221 which again yields the desired conclusion . so , in the gaussian case lemma [ l4 ] is proved . another way to prove this lemma , is to notice first that the weak convergence of @xmath174 to @xmath222 ( established in lemma [ l1 ] ) is uniform with respect to @xmath223 for any compact @xmath224 . indeed , the uniformity of the convergence of the characteristic functions in the proof of lemma [ l1 ] is obvious , and so one can apply , for example , theorem 7 from appendix i of @xcite , whose remaining conditions are easily checked . finally , reminding that @xmath228 and denoting @xmath229 the distribution function of the standard gaussian law , we get @xmath230 for @xmath231 . the last expression does not depend on @xmath232 and clearly converges to @xmath11 as @xmath233 , so the assertion of the lemma follows . in order to estimate the last factor we write @xmath235 now , let us observe that the random walk @xmath236 , @xmath237 , has the same law as the restriction on @xmath238 of a standard brownian motion @xmath3 . so , @xmath239 with an evident notation . it is known that the random variable @xmath240 is exponential of parameter @xmath12 @xmath74see , for example , @xcite@xmath75 and hence , using its moment generating function @xmath241 , we get @xmath242 finally , taking @xmath105\,0\,{,}\;1/12\,\right[$ ] we have @xmath243\,0\,{,}\;1/8\,\right[$ ] and , combining , and using lemma [ l3 ] , we finally obtain @xmath244 for all sufficiently small @xmath33 and all @xmath107 , which concludes the proof in the gaussian case . in the general case the proof is almost the same . note that we have no longer the symmetry of the process @xmath87 , so we need to consider the cases @xmath245 and @xmath246 separately . besides that , the only difference is in the derivation of the bound . here we get @xmath247 where @xmath240 is the supremum of the random walk @xmath248 , @xmath237 , with @xmath249 . note that @xmath250 and so , the cummulant generating function @xmath251 of @xmath252 admits a strictly positive zero @xmath253 . hence , by the well - known cramr - lundberg bound on the tail probabilities of @xmath240 @xmath74see , for example , theorem 5.1 from chapter xiii of @xcite@xmath75 , we have @xmath254 for all @xmath255 . finally , denoting @xmath256 the distribution function of @xmath240 and using this bound we obtain @xmath257_{-\infty}^{+\infty}-\ ; \frac12\int_{{\mathbb{r}}}e^{\,x/2}\bigl(f(x)-1\bigr)\;dx\\ & = \frac12\int_{{\mathbb{r}}_-}e^{\,x/2}\;dx+ \frac12\int_{{\mathbb{r}}_+}e^{\,x/2}\bigl(1-f(x)\bigr)\;dx\\ & { \leqslant}1+\frac12\int_{{\mathbb{r}}_+}e^{-x/2}\;dx=2 , \end{aligned}\ ] ] which concludes the proof . rubin , h. and song , k .- s . , `` exact computation of the asymptotic efficiency of maximum likelihood estimators of a discontinuous signal in a gaussian white noise '' , _ ann.statist . _ * 23 * , no . 3 , pp . 732739 , 1995 .

different change - point type models encountered in statistical inference for stochastic processes give rise to different limiting likelihood ratio processes . in a previous paper of one of the authors it was established that one of these likelihood ratios , which is an exponential functional of a two - sided poisson process driven by some parameter , can be approximated ( for sufficiently small values of the parameter ) by another one , which is an exponential functional of a two - sided brownian motion . in this paper we consider yet another likelihood ratio , which is the exponent of a two - sided compound poisson process driven by some parameter . we establish , that similarly to the poisson type one , the compound poisson type likelihood ratio can be approximated by the brownian type one for sufficiently small values of the parameter . we equally discuss the asymptotics for large values of the parameter and illustrate the results by numerical simulations . * keywords * : compound poisson process , non - regularity , change - point , limiting likelihood ratio process , bayesian estimators , maximum likelihood estimator , limiting distribution , limiting mean squared error , asymptotic relative efficiency * mathematics subject classification ( 2000 ) * : 62f99 , 62m99

a new double neutron star ( dns ) system , j07373039 , was recently discovered ( burgay et al . 2003 ) . this is the fifth galactic dns ; all share the same characteristics of having eccentric orbits ( @xmath5 ) and short pulse periods ( 22 104 ms ) and low period derivatives ( @xmath6 ) . the two latter parameters imply a weak surface magnetic field ( @xmath7 g ) which indicates that the pulsar has been recycled ( smarr & blandford 1976 ; alpar et al . 1982 ; radhakrishnan & srinivasan 1982 ) , and that the observed pulsar in each system is the older neutron star and has gone through a mass - transfer phase ( srinivasan & van den heuvel 1982 ) . dewi & pols ( 2003 ) found that the wide - orbit dnss j1518 + 4904 and j18111736 are produced from helium star - neutron star binaries that avoided roche - lobe overflow ( rlof ) ; while the close - orbit b1913 + 16 and b1534 + 12 can be formed either with or without a mass - transfer phase in the helium star - neutron star binary stage of evolution . among the five galactic dnss , j07373039 has the shortest spin period ( 22 ms ) , shortest orbital period ( @xmath8 ) , and lowest eccentricity ( 0.088 ) . in this paper we examine the possible formation history of j07373039 . we will show that unlike the other dnss , j07373039 can only be formed from helium star - neutron star binaries which have gone through rlof . we examine the formation history of the system is terms of the so - called standard scenario ( bhattacharya & van den heuvel 1991 ) , in which dnss were formed from be / x - ray binaries . when the be star leaves the main sequence and becomes a giant , a runaway mass transfer takes place due to the large mass ratio of the system . the neutron star is engulfed by the giant s envelope , and a common - envelope ( ce ) phase ensues in which the neutron star spirals down to the helium core of the giant , ejecting its hydrogen - rich envelope in this process . the outcome of this spiral - in is a very close binary consisting of a helium star and a neutron star ( hes - ns ) . for companions less massive than about 5 @xmath1 , this mass transfer can still be stabilized such that the formation of a ce can be avoided ( e.g. king & ritter 1999 ; podsiadlowski & rappaport 2000 ; tauris , van den heuvel , savonije 2000 ) . however , for more massive companions such as the be stars considered here the formation of a ce can not be avoided . the helium star evolves further through core - helium burning and further burning stages . during this evolution it transfers mass to the neutron star by rlof and also loses mass by stellar wind . [ 0737:fig : presn ] depicts the parameters of these hes - ns binaries at the end of this rlof and wind mass loss , resulting from detailed evolutionary calculations ( dewi et al . 2002 ; dewi & pols 2003 ) . the number indicated at each curve represents the initial mass of the helium star at the beginning of its evolution . the stars indicate the outcome of the evolution of systems with a range of initial orbital periods ( note that the lines connecting the stars are not evolutionary tracks ) . also presented in the figure are the maximum and minimum possible orbital periods of the progenitor of j07373039 just prior to the supernova ( sn ) explosion . these lines are derived with the assumption that the pre - sn ( circular ) orbital separation , @xmath9 , lies between the periastron and apastron of the post - sn separation , i.e. @xmath10 ( flannery & van den heuvel 1975 ) , where @xmath11 and @xmath12 are the post - sn separation and eccentricity . here @xmath11 and @xmath12 are the parameters at the time when it was born , which is assumed to be a characteristic time ago , @xmath13 . these parameters were derived by integrating the effects of gravitational - wave radiation on the observed ( @xmath14 , @xmath15 ) over @xmath16 . . the shaded area marks the region where the helium stars never fill their roche lobes . the maximum and minimum pre - sn orbital period of j07373039 are represented by the upper and lower thick lines , derived from the separation of the system at the time it was born , i.e. a characteristic spin - down time ago.,width=317 ] dewi & pols ( 2003 ) found that systems represented with the open star symbols undergo a common - envelope ( ce ) phase due to the development of a helium convective envelope . the consequence of this is that , after the ce phase these systems will have a lower mass ( @xmath17 @xmath1 ) and much shorter orbital period ( @xmath18 ) than their original parameters shown in fig . [ 0737:fig : presn ] . hence , only the helium stars represented by solid star symbols ( i.e. with initial masses in the range of 4 6.5 @xmath1 ) are possible progenitors of j07373039 . this range of mass requires an initial progenitor main - sequence star of 14 20 @xmath1 . the region of the possible pre - sn orbital period @xmath19 limited by the two thick lines in fig . [ 0737:fig : presn ] does not cross the shaded area where the helium stars never fill their roche lobes . this implies that j07373039 can only have been formed through roche - lobe mass transfer from the helium star progenitor as opposed to the other four galactic dnss which could be formed either via rlof or without a mass - transfer phase ( dewi & pols 2003 ) . [ 0737:fig : kick ] depicts an enlargement of the region of allowed final hes - ns systems from fig . [ 0737:fig : presn ] in an @xmath9 vs. @xmath20 diagram ( the stars are the same as the allowed systems in fig . [ 0737:fig : presn ] ) . for a given combination of pre - sn helium star mass @xmath20 and orbital separation @xmath9 we calculated the kick velocity required to produce the post - sn orbital period and eccentricity . [ 0737:fig : kick ] shows the ranges of the required kick velocities @xmath21 limited by the curves of @xmath22 70 , 125 , 175 and 230 @xmath4 . the region where the systems undergo a ce phase and evolve to extremely short orbital periods is to the left of the dash - dotted line in fig . [ 0737:fig : kick ] . assuming that only systems which do not go through the ce phase are the possible progenitors of j07373039 ( i.e. the systems on the right - hand side of the line ) , we find that to explain the orbital parameters of j07373039 when it was born ( i.e. @xmath23 @xmath24 and @xmath25 ; assuming that the pulsar s age equals its characteristic age ) , a minimum kick velocity of 70 @xmath4 is required at the birth of the pulsar s companion . are presented at the bottom of the figure).,width=317 ] the minimum separation , below which mass - transfer phase from the helium star to a neutron star is dynamically unstable resulting in a merger of the two stars ( dewi et al . 2002 ) , is marked by the dotted line in fig . [ 0737:fig : kick ] . this line gives a constraint on the maximum kick velocity , i.e. 230 @xmath4 . all five double neutron star systems ( dnss ) in eccentric orbits in the galactic disk share the characteristic of a combination of a weak dipole magnetic field ( in the range @xmath26 to @xmath27 g ) and rapid spin , indicating that we are dealing here with recycled pulsars that have been spun up during an accretion phase ( smarr & blandford 1976 ; alpar et al . 1982 ; radhakrishnan & srinivasan 1982 ; srinivasan & van den heuvel 1982 ) . during such a phase with a non - degenerate donor companion the orbit will have been tidally circularized . therefore the present eccentricity of these systems can only have been induced in the second supernova explosion when the companion collapsed to a neutron star ( srinivasan & van den heuvel 1982 ) . the reduction of the magnetic field strength of the pulsar to a value around @xmath26 to @xmath28 g is thought to somehow be the result of the accretion , as there is an observed correlation between the amount of matter accreted and the field strength ( taam & van den heuvel 1986 ) . a simple relation for this case was derived semi - empirically , by shibazaki et al . ( 1989 ) : @xmath29 where @xmath30 and @xmath31 are the present and initial magnetic field strengths , respectively , @xmath32 is the amount of matter accreted and @xmath33 is a constant to be derived from the observations . francischelli et al . ( 2002 ) found @xmath34 @xmath35 @xmath1 to agree well with the observed data for low mass x - ray binaries . adopting this value and a duration of the roche - lobe overflow phase of the helium star of @xmath36 yrs ( this is about the average value for helium stars in the mass range 4.0 to 6.3 @xmath1 ( dewi et al . 2002 ; dewi & pols 2003 ) ) , with accretion at an eddington rate for helium ( @xmath37 @xmath38 ) one finds that @xmath30 can have decreased by a factor of about 50 during this phase alone . furthermore , a 15 @xmath1 be star resides @xmath39 yrs on the main - sequence . be / x - ray binaries tend to be transients ( rappaport & van den heuvel 1982 ; van den heuvel & rappaport 1987 ; zikowski 2002 ) and are `` on '' as an x - ray source only part of the time , during which they often reach a luminosity close to the eddington limit . assuming them to be `` on '' only one per cent of the time and then to reach the eddington limit , the neutron star will during the be / x - ray binary phase have accreted about @xmath40 @xmath1 . with eq . ( [ 0737:eq : field ] ) this is already sufficient to reduce its magnetic field by a factor of about 100 . so , adding the amount of matter accreted during the be / x - ray binary phase and the rlof of the helium star , one finds with eq . ( [ 0737:eq : field ] ) that these phases together provide enough accretion to reduce the magnetic field by a factor of about 200 . magnetic fields of young pulsars on average typically have a dipole strength a few times @xmath41 g , and after reduction by this factor will typically be around @xmath28 g , as observed in the five dnss . as to the spin - up of the `` old '' neutron star : during the roche - lobe overflow from the helium star accretion to the neutron star will have proceeded through a disk . the amount of angular momentum accreted during this phase can be calculated as follows . the mass transfer rate during roche - lobe overflow is highly super - eddington , in the range @xmath42 @xmath38 for helium stars in the mass range 4.0 6.3 @xmath1 ( dewi et al . 2002 ; dewi & pols 2003 ) . dewi et al . ( 2002 ) and dewi & pols ( 2003 ) in their calculations of the evolution of the systems during this phase assumed the accretion rate onto the neutron star to be the eddington rate ( @xmath37 @xmath38 ) and the super - eddington fraction of the transferred matter to be blown out of the system by the radiation pressure , carrying with it the specific angular momentum equal to the specific orbital angular momentum of the neutron star . following this assumption of accretion at the eddington rate as radiation pressure will prevent accretion at a higher rate and using the dipole strength of the magnetic field of j07373039 of @xmath0 g , one can calulate the value of the alfven - radius @xmath43 , where the matter becomes coupled to the magnetic field and starts to co - rotate with the neutron star magnetosphere . @xmath43 is given by ( e.g. see bhattacharya & van den heuvel 1991 ) ) : @xmath44 where @xmath45 is the dipole field strength in units of @xmath26 g , @xmath46 is the neutron star radius in units of @xmath47 cm , @xmath48 and @xmath49 are the accretion rate and the eddington accretion rate for hydrogen , respectively and @xmath50 is the mass of the neutron star . with the dipole field strength of @xmath0 g of psr j07373039 , the eddington rate for helium accretion @xmath51 @xmath37 @xmath38 and a @xmath50 = 1.3 @xmath1 one obtains @xmath43 = 78.4 km . the rate at which angular momentum is accreted by the neutron star is then : @xmath52 where @xmath53 is the keplerian angular velocity of matter in the disk at distance @xmath54 from the center of the neutron star . with @xmath55 , @xmath56 @xmath1 one finds @xmath57 . the present spin angular momentum of the neutron star is @xmath58 where @xmath59 and @xmath60 are the radius and spin period of the neutron star and @xmath61 is its radius of gyration , respectively . the value of @xmath62 is typically about 0.075 for a polytropic index @xmath63 ( e.g. lattimer & prakash 2001 ) . with this value and @xmath64 km and @xmath60 = 22 ms one obtains @xmath65 , which together with the above mentioned rate of accretion of angular momentum results in a required timescale for the spin - up of about @xmath66 years . the duration of the phase of roche - lobe overflow in the helium star plus neutron star binaries with helium star masses between 4.0 and 6.3 @xmath1 ranges from 2.4 to @xmath67 years , which is of the same order as the value of @xmath66 years required for the spin - up . it thus appears that the magnetic field strength and spin rate of psr j07373039 fit quite well with evolutionary model presented here in which the immediate progenitor system was a very close helium star plus neutron star binary which evolved through a phase of roche lobe overflow with a duration of order @xmath68 years . as mentioned above , the progenitor of this system was so close that it can not have avoided the phase of mass transfer by roche - lobe overflow from the helium star ( dewi & pols 2003 ) , so here this phase must absolutely have taken place in the history of psr j07373039 . this may be the reason why the pulsar has the shortest spin period of all . the progenitors of the other systems may , in principle , have avoided rlof , although it can certainly not be excluded that also in ( some of ) them roche - lobe overflow from the helium star may have taken place . we have examined the formation of j07373039 . we find that this system must have gone through a mass - transfer phase from a helium star with the initial mass in the range of 4 6.3 @xmath1 . we also find that an asymmetric sn explosion with a kick velocity of 70 230 @xmath4 is necessary to explain the observed orbital parameters . however , these constraints may still be subject to some uncertainties . whether the neutron stars in the systems that go through a ce phase ( the open stars in fig . [ 0737:fig : presn ] ) complete the spiral - in in the envelope of the helium star depends on the competition between the spiral - in timescale and the time left before the explosion of the helium star ( dewi & pols 2003 ) . if the sn explosion in systems with open star symbols in fig . [ 0737:fig : presn ] occurs before the neutron star completes the spiral - in process , a lower kick velocity or even a symmetric sn explosion ( shown as the solid circle ) would then be possible . furthermore , the constraints on the maximum pre - sn mass and the maximum kick velocity depend somewhat on the assumed wind mass - loss rate and the loss of angular momentum during the rlof . as the stability of a mass - transfer phase depends on the mass ratio of the system and the period at the onset of rlof , applying a higher wind mass - loss rate results in a lower mass helium star in wider orbit , and hence , more stable mass transfer than adopting wind mass loss with a lower rate . this work was sponsored by nwo spinoza grant 08 - 0 to e. p. j. van den heuvel . we thank dick manchester for releasing the observational data of the system prior to publication , onno pols and andrea possenti for suggestions and discussions , and hans ritter for his referee comments . alpar m. a. , cheng a. f. , ruderman m. a. , shaham j. , 1982 , nature 300 , 728 bhattacharya d. , van den heuvel e. p. j. , 1991 , phys . 203 , 1 burgay m. , damico n. , possenti a. , manchester r. n. , lyne a. g. , joshi b. c. , mclaughlin m. a. , kramer m. , sarkissian j. m. , camilo f. , kalogera v. , kim c. , lorimer d. r. , 2003 , nature 426 , 531 dewi j. d. m. , pols o. r. , 2003 , mnras 344 , 629 dewi j. d. m. , pols o. r. , savonije g. j. , van den heuvel e. p. j. , 2002 , mnras , 331 , 1027 flannery b. p. , van den heuvel e. p. j. , 1975 , a&a 39 , 61 francischelli g. j. , wijers r. a. m. j. , brown g. e. , 2002 , apj 565 , 471 lattimer j. m. , prakash m. , 2001 , apj 550 , 426 radhakrishnan v. , srinivasan g. , 1982 , cur . 51 , 1096 rappaport s. , van den heuvel e. p. j. , 1982 , in jaschek m. , groth h .- g . , eds . , iau symp . 98 : be stars , p. 327 shibazaki n. , murakami t. , shaham j. , nomoto k. , 1989 , nature 342 , 656 smarr l. l. , blandford r. , 1976 , apj 207 , 574 srinivasan g. , van den heuvel e. p. j. , 1982 , a&a 108 , 143 taam r. e. , van den heuvel e. p. j. , 1986 , apj 305 , 235 tauris t. m. , van den heuvel e. p. j. , savonije g. j. , 2000 , apj 530 , l93 van den heuvel e. p. j. , rappaport s. , 1987 , in physics of be stars , p. 291 zikowski j. , 2002 , mem . ital . , 73 , 1038

we find that the orbital period ( 2.4 hours ) , eccentricity ( 0.09 ) , dipole magnetic field strength ( @xmath0 gauss ) and spin period ( 22 ms ) of the new highly relativistic double neutron star system psr j07373039 can all be consistently explained if this system originated from a close helium star plus neutron star binary ( hes - ns ) in which at the onset of the evolution the helium star had a mass in the range 4.0 to 6.5 @xmath1 and an orbital period in the range 0.1 to 0.2 days . such systems are the post - common - envelope remnants of wide be / x - ray binaries ( orbital period @xmath2 100 to 1000 days ) which consist of a normal hydrogen - rich star with a mass in the range 10 20 @xmath1 and a neutron star . the close hes - ns progenitor system went through a phase of mass transfer by roche - lobe overflow at a high rate lasting a few times @xmath3 years ; assuming eddington - limited disk accretion onto the neutron star this star was spun up to its present rapid spin rate . at the moment of the second supernova explosion the he star had a mass in the range 2.3 to 3.3 @xmath1 and in order to obtain the present orbital parameters of psr j07373039 a kick velocity in the range 70 230 @xmath4 must have been imparted to the second neutron star at its birth . [ firstpage ] stars : evolution binaries : general stars : neutron pulsars : individual : j07373039 supernovae : general

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The Congress finds that-- (1) the utility sector is the largest single source of greenhouse gas emissions in the United States today, producing approximately one-third of the country's emissions; (2) heating and cooling homes accounts for nearly 60 percent of residential electricity usage in the United States; (3) shade trees planted in strategic locations can reduce residential cooling costs by as much as 30 percent; (4) strategically planted shade trees can provide significant carbon benefits both directly (sequestration by the growing tree) and indirectly (reductions in carbon emissions from electricity conservation); (5) trees can reduce the rate and magnitude of stormwater runoff and improve surface water quality; (6) trees reduce topsoil erosion, prevent harmful land pollutants contained in soil from getting into our waterways, slow down water run-off, and ensure that our groundwater supplies are continually being replenished; and (7) trees strategically placed on or near residential property can increase a home's property value. SEC. 3. DEFINITIONS. As used in this Act: (1) The term ``nonprofit tree-planting organization'' means any organization described in section 501(c)(3) of the Internal Revenue Code of 1986 (26 U.S.C. 501(c)(3)), that is exempt from taxation under section 501(a) of such Code (26 U.S.C. 501(a)), which exists, in whole or in part, to-- (A) expand urban and residential tree cover; (B) distribute young trees for planting; (C) increase awareness of the environmental and energy-related benefits of trees; (D) educate the public about proper tree planting, care, and maintenance strategies; or (E) carry out any combination of the foregoing activities. (2) The term ``retail power provider'' means any entity authorized under applicable State or Federal law to generate, distribute, or provide retail electricity, natural gas, or fuel oil service. (3) The term ``Secretary'' means the Secretary of Energy. (4) The term ``State'' means each of the several States, the District of Columbia, and each commonwealth, territory, or possession of the United States. (5) The term ``tree-siting guidelines'' means a comprehensive list of science-based measurements outlining the species and minimum distance required between trees planted pursuant to this Act, in addition to the minimum required distance to be maintained between such trees and-- (A) building foundations; (B) air conditioning units; (C) driveways and walkways; (D) property fences; (E) preexisting utility infrastructure; (F) septic systems; (G) swimming pools; and (H) other infrastructure as determined appropriate. SEC. 4. PURPOSE. The purpose of this Act is to assist retail power providers with the establishment and operation of targeted residential tree-planting programs, for the following purposes: (1) Reducing the peak-load demand for electricity in residential areas during the summer months through direct shading of residential buildings provided by strategically planted trees. (2) Reducing wintertime demand for energy in residential areas by blocking cold winds from reaching homes, which lowers interior temperatures and drives heating demand. (3) Protecting air quality and public health by removing harmful pollution from the air. (4) Utilizing the natural photosynthetic and transpiration process of trees to lower ambient temperatures and absorb carbon dioxide, thus mitigating the effects of climate change. (5) Lowering electric bills for residential ratepayers by limiting electricity consumption without reducing benefits. (6) Relieving financial and demand pressure on retail power providers that stems from large peak-load energy demand. (7) Protecting water quality and public health by reducing stormwater runoff and keeping harmful pollutants from entering waterways. (8) Promoting community education, involvement, and stewardship of much-needed tree canopy coverage in residential communities. SEC. 5. GENERAL AUTHORITY. (a) Authority.--The Secretary may establish a grant program to provide financial, technical, and related assistance to retail power providers to support the establishment of new, or continued operation of existing, targeted residential tree-planting programs. (b) Public Recognition Initiative.--In addition to the authority provided under subsection (a), the Secretary may also create a national public recognition initiative to encourage participation in tree- planting programs by retail power providers. (c) Cooperation.--In carrying out the grant program established pursuant to subsection (a), the Secretary may cooperate with, and provide financial, technical, and related assistance for such cooperation to, State foresters or equivalent State officials. (d) Requirements for Qualified Tree-Planting Programs.--In order to qualify for assistance under this Act, a retail power provider shall, in accordance with this Act, establish and operate, or continue operating, a tree-planting program that meets each of the following requirements: (1) The program shall provide free or discounted shade- providing or wind-reducing trees to residential consumers interested in lowering their home energy costs. (2) The program shall optimize the electricity-consumption reduction benefit of each tree by planting in strategic locations around a given residence. (3) The program shall either-- (A) provide maximum amounts of shade during summer intervals when residences are exposed to the most sun intensity; or (B) provide maximum amounts of wind protection during fall and winter intervals when residences are exposed to the most wind intensity. (4) The program shall use the best available science to create and utilize tree-siting guidelines which dictate where the optimum tree species are best planted in locations that ensure adequate root development and that achieve maximum reductions in consumer energy demand while causing the least disruption to public infrastructure, considering overhead and underground facilities. (5) The program shall provide tree recipients with tree planting and tree care instruction and education prior to or in conjunction with delivery of free or discounted trees. (6) The program shall receive certification from the Secretary that it is designed to achieve the goals set forth in paragraphs (1) through (5). In designating criteria for such certification, the Secretary shall collaborate with the Forest Service's Urban and Community Forestry Program to ensure that certification requirements are consistent with such goals. (e) New Program Funding Share.--The Secretary shall ensure that no less than 30 percent of the funds made available under this Act are distributed to retail power providers which-- (1) have not previously established or operated qualified tree-planting programs; or (2) are operating qualified tree-planting programs which were established no more than three years prior to the date of enactment of this Act. SEC. 6. AGREEMENTS BETWEEN RETAIL POWER PROVIDERS AND NONPROFIT TREE- PLANTING ORGANIZATIONS. (a) Grant Authorization.--In providing assistance under this Act, the Secretary is authorized to award grants only to retail power providers that have entered into binding legal agreements with nonprofit tree-planting organizations. (b) Conditions of Agreement.--An agreement between a retail power provider and a nonprofit tree-planting organization under subsection (a) shall set forth conditions under which such nonprofit tree-planting organization shall carry out a targeted residential tree-planting program. Such conditions-- (1) shall require the organization to participate in a local technical advisory committee in accordance with section 7; and (2) may require the organization to-- (A) coordinate volunteer recruitment to assist with the physical act of planting trees in residential locations; (B) undertake public awareness campaigns to educate local residents about the benefits, cost savings, and availability of free shade trees; (C) establish education and information campaigns to encourage recipients to maintain their shade trees over the long term; (D) serve as the point of contact for existing and potential residential participants who have questions or concerns regarding the tree-planting program; (E) require tree recipients to sign agreements committing to voluntary stewardship and care of provided trees; (F) monitor and report on the survival, growth, overall health, and estimated energy savings of provided trees up until the end of their establishment period which shall be no less than five years; and (G) ensure that trees planted near existing power lines will not interfere with energized electricity distribution lines when mature, and that no new trees will be planted under or adjacent to high-voltage electric transmission lines without prior consultation with the applicable retail power provider receiving assistance under this Act. (c) Lack of Nonprofit Tree-Planting Organization.-- (1) In general.--If a qualified nonprofit tree-planting organization does not exist or operate within areas served by retail power providers applying for assistance under this Act, the requirements of this section shall apply to binding legal agreements entered into by such retail power providers and one of the following entities: (A) Local municipal governments with jurisdiction over the urban or suburban forest. (B) Conservation districts. (2) Cooperative agreements.--With respect to an area described in paragraph (1), a local municipal government or conservation district that enters into a binding legal agreement with a retail power provider pursuant to such paragraph may, to fulfill the conditions of such binding legal agreement, enter into a cooperative agreement with a not-for- profit organization in such area that exists in whole, or in part, to meet the goals and objectives described in subparagraphs (A) through (E) of section 3(1). SEC. 7. TECHNICAL ADVISORY COMMITTEES. (a) Description.--In order to qualify for assistance under this Act, a retail power provider shall consult with the nonprofit tree- planting organization with which it has entered into a binding legal agreement under section 6 and State foresters or equivalent State officials to establish a local technical advisory committee which shall provide advice and consultation to the applicable tree-planting program. The advisory committee may-- (1) design and adopt an approved plant list that emphasizes the use of hardy, noninvasive tree species and, where geographically appropriate, the use of native or low water-use shade trees or both; (2) design and adopt planting, installation, and maintenance specifications and create a process for inspection and quality control; (3) ensure that tree recipients are educated to care for and maintain their trees over the long term; (4) help the public become more engaged and educated in the planting and care of shade trees; (5) prioritize which sites receive trees, giving preference to locations with the most potential for energy conservation and secondary preference to areas where the average annual income is below the regional median; and (6) assist with monitoring and collection of data on tree health, tree survival, and energy conservation benefits generated under this Act. (b) Compensation.--Individuals serving on local technical advisory committees shall not receive compensation for their service. (c) Composition.--Local technical advisory committees shall be composed of representatives from public, private, and nongovernmental organizations with expertise in demand-side energy efficiency management, urban forestry, or arboriculture, and shall be composed of the following: (1) Up to 4 persons, but no less than one person, representing the retail power provider receiving assistance under this Act. (2) Up to 4 persons, but no less than one person, representing the nonprofit tree-planting organization which will partner with the retail power provider to carry out this Act. (3) Up to 3 persons representing local nonprofit conservation or environmental organizations. Preference shall be given to those organizations which are organized under section 501(c)(3) of the Internal Revenue Code of 1986, and which have demonstrated expertise engaging the public in energy conservation, energy efficiency, or green building practices or a combination thereof, such that no single organization is represented by more than one individual under this subsection. (4) Up to 2 persons representing a local affordable housing agency, affordable housing builder, or community development corporation. (5) Up to 3, but no less than one, persons representing local city or county government for each municipality where a shade tree-planting program will take place and at least one of these representatives shall be the city or county forester, city or county arborist, conservation district forester or functional equivalent. (6) Up to one person representing the local government agency responsible for management of roads, sewers, and infrastructure, including public works departments, transportation agencies, or equivalents. (7) Up to 2 persons representing the nursery and landscaping industry. (8) Up to 2 persons, but no less than one person, representing State foresters or equivalent State officials. (9) Up to 3 persons representing the research community or academia with expertise in natural resources or energy management issues. (d) Chairperson.-- (1) In general.--Each local technical advisory committee shall elect a chairperson to preside over Committee meetings, act as a liaison to governmental and other outside entities, and direct the general operation of the committee. (2) Eligibility.--Only committee representatives under subsection (c)(1) or subsection (c)(2) shall be eligible to act as a local technical advisory committee chairperson. (e) Credentials.--At least one of the members of each local technical advisory committee shall be certified with one or more of the following credentials: International Society of Arboriculture; Certified Arborist, ISA; Society of American Foresters Certified Forester; Certified Arborist Municipal Specialist, ISA; Certified Arborist Utility Specialist, ISA; Board Certified Master Arborist; or Landscape Architect recommended by the American Society of Landscape Architects. SEC. 8. COST-SHARE PROGRAM. (a) Federal Share.--The Federal share of support for any tree- planting program funded under this Act shall not exceed 50 percent of the cost of such program and shall be provided on a matching basis. (b) Non-Federal Share.--The non-Federal share of such costs may be paid or contributed by any governmental or nongovernmental entity other than from funds derived directly or indirectly from an agency or instrumentality of the United States. SEC. 9. RULEMAKING. (a) Rulemaking Period.--The Secretary is authorized to solicit comments and initiate a rulemaking period that shall last no more than 6 months after the date of enactment of this Act. (b) Competitive Grant Rule.--At the conclusion of the rulemaking period under subsection (a), the Secretary shall promulgate a rule governing a public, competitive grants process through which retail power providers may apply for Federal assistance under this Act. SEC. 10. NONDUPLICITY. Nothing in this Act shall be construed to supersede, duplicate, cancel, or negate the programs or authorities provided under section 9 of the Cooperative Forestry Assistance Act of 1978 (16 U.S.C. 2105). SEC. 11. AUTHORIZATION OF APPROPRIATIONS. There are authorized to be appropriated such sums as may be necessary to carry out this Act.

The Residential Energy and Economic Savings Act or the TREES Act - Authorizes the Secretary of Energy (DOE)&nbsp;to: (1) establish a grant program to provide financial, technical, and related assistance to retail power providers to support the establishment of new, or continued operation of existing, targeted residential tree-planting programs; and (2) create a national public recognition initiative to encourage such providers to participate in such programs. Sets forth requirements that must be met for tree-planting programs to qualify for assistance, including a requirement to provide free or discounted shade-providing or wind-reducing trees to residential consumers interested in lowering their home energy costs. Authorizes the Secretary to award grants only to providers that have entered into binding legal agreements with nonprofit tree-planting organizations. Requires a provider, in order to qualify for assistance, to consult with such organization and state foresters to establish a local technical advisory committee, which shall provide advice and consultation to the program. Authorizes the advisory committee to: (1) design and adopt an approved plant list that emphasizes the use of hardy, noninvasive tree species, native or low water-use shade trees, or both; (2) design and adopt planting, installation, and maintenance specifications and create a process for inspection and quality control; (3) ensure that tree recipients are educated to care for and maintain their trees over the long term; (4) help the public become more engaged and educated in the planting and care of shade trees; (5) prioritize which sites receive trees, giving preference to locations with the most potential for energy conservation and secondary preference to areas where the average annual income is below the regional median; and (6) assist with monitoring and collection of data on tree health, tree survival, and energy conservation benefits generated under this Act.

telemedicine can be defined as the use of telecommunication technologies to provide medical information and service . historically , it started more than 4 decades ago to allow communication and discussion between physicians of small hospitals and those of large tertiary care hospitals for non - acute cases where advanced treatment must be planned and agreed on . therefore , telemedicine started in an asynchronous module where data can be stored and forwarded and then reviewed offline . however , acute care has developed significantly in the last few decades as well as telecommunication technologies , which made synchronous telemedicine possible and in a different format from telephone - based to audio - video teleconference , and this may go further with the attachment of peripheral devices for robotic surgery or procedures under tele - guidance . we can define telestroke as the emergency use of telecommunication technologies to provide appropriate acute stroke therapy at a distance . a telestroke program using telephone consultation is cheap and takes less time to initiate and to complete , however , it is associated with significant limitations and the risk of making a wrong diagnosis or at least inaccurate acute stroke related deficit evaluation , and then the wrong thrombolysis decision . most of the current telestroke programs use synchronous two - way audio - video teleconferences , and this is our area of interest in this article . the patient is clinically evaluated using the national institute of health stroke scale ( nihss ) and the brain image is reviewed by a stroke neurologist from a distance , and then a thrombolysis decision is taken . in one randomized controlled study , the audio - video teleconference was compared to the telephone - based telestroke and was found to be more sensitive , more specific , and more likely to lead to the right thrombolysis decision.3,4 after confirming the diagnosis of acute stroke , there are 2 important measures to increase the recanalization rate with significant clinical benefit : thrombolysis rate ( percentage of acute stroke patients who received iv t - pa within the therapeutic window ) and iv t - pa needle time ( time from stroke onset to iv t - pa bolus ) . currently , 2 options exist for acute stroke patients care in medically under served areas : either urgent patient transfer to a tertiary care hospital where acute stroke treatment can be administered , or managing the patient at the local hospital . patient transfer can be via ambulance or air evacuation , which is associated with high transportation costs , smaller increase in thrombolysis rate , and smaller chance for significant recovery if they were treated , because most likely the iv t - pa needle time will be within the last third of the therapeutic time - window , which is associated with higher number needed to treat.5 the second option necessitates telestroke technology so stroke experts share with local physicians the duty of applying evidence - based acute stroke therapy . we need to look here for 2 measures , the validity of patient assessment using the nihss through teleconference , and the effectiveness , including success , and complication rate , of telestroke based intravenous thrombolysis . few studies have looked into the accuracy of patient assessment using the nihss . in one study,6 the nihss scores of 20 patients were compared to their nihss scores carried out remotely through a broadband - connected workstation . both assessments were carried out by qualified neurologists . paired t tests and pearson correlation coefficients were very strong ( r=0.9552 , p=0.0001 ) indicating that high scores in bedside correlate with high scores remotely . for the second measure , we will review published data from major telestroke programs in europe and north america . the reach telestroke network started in 2003 in georgia , usa.7 by 2005 , the network had 7 hospitals in rural areas connected to the medical college of georgia via one - way video and two - way audio teleconference system . between march 2003 and may 2005 , 194 acute stroke consultations were made within the 3-hour therapeutic window and 30 patients with a median nihss of 12.5 were treated with iv t - pa . rapid improvement defined as a drop of 4 or more nihss points within 24 hours occurred in 18 out of 30 treated patients , and no symptomatic intracerebral hemorrhage occurred . the study interestingly showed a significant reduction in onset to treatment after one year of operation from 143 to 111 minutes . the most common reasons for not treating were rapid improvement , nihss was below 4 , beyond therapeutic window , or presence of seizure or hemorrhage prior to treatment . some other data recently published represents the experience of the university of pittsburg medical center telestroke network with its 12 spoke facilities through audio - video conferencing equipment.8 between july 2008 and december 2009 , 351 telestroke consultations were performed . eighty - three stroke patients received iv t - pa at the spoke hospitals , and 59 patients at the hub center . the 2 groups were similar in their baseline characteristics including median nihss scores and mean onset to treatment time . the mean arrival to treatment time was longer in the telestroke patients ( 67.8 versus 98.9 minutes ) . the study showed no statistical significant difference between the 2 groups in favorable outcomes , symptomatic intracerebral hemorrhage , and mortality rates . the northern alberta telestroke service started in 2003.9 by 2007 , 7 spoke centers were connected to the university of alberta hospital ( 4 via audio - video teleconference , and 3 via telephone only ) . in their first 2 years of experience , the telestroke was activated 210 times and only 44 patients were candidates for thrombolysis using iv ten ( 23% ) of them were assessed by the er physician at the spoke centers without video assessment by a stroke neurologist . sixteen ( 40% ) patients had a modified rankin scale less than 2 by 90 days from iv t - pa , and 9 deaths occurred within 90 days from iv thrombolysis . only 2 ( 4.5% ) of the treated patients had t - pa complications with intracerebral hemorrhage , and the rest died due to other mechanisms . the telemedical project for integrative stroke care ( tempis ) was established in 2003 serving a large area in south east bavaria , germany.10 it comprised 12 spoke hospitals connected to 2 academic centers in munich via video teleconference and ct / mri image transfer . currently , tempis is considered to be the largest telemedical stroke service in the world . tempis was associated with significant improvement of acute in - hospital stroke treatment in terms of quality indicators such as rapid brain imaging , thrombolysis rate , assessment of swallowing disorders , and early rehabilitation therapy.11 when patients served with tempis were compared to similar acute stroke patients within the same region , but not served with telemedicine , tempis showed significant reduction in death and dependency outcome at 3 , 12 , and 30 months,10,12 without a significant difference in mortality rate alone . the thrombolysis rate in most of the published data of different telestroke networks ranges from 18 - 51%.7 - 10 reasons for no iv t - pa include stroke onset beyond 270 minutes , presence of contraindication that was not recognized by the er physician at the spoke hospital , or patient having a stroke mimic like seizure with todd s paralysis , cns neoplasm with sudden deterioration , cns infection , and others . considering the threat of these acute stroke mimics , on - call stroke neurologists are still of great benefit to the patients and the spoke hospitals . the small waste of telestroke resources on acute stroke mimics is well compensated by the gain of managing these urgent neurological conditions despite the fact that some patients were required to be transferred to the university hospital anyway . with time and experience there are 3 nonexclusive methods of clinical operation of telestroke : drip and keep , which means after telestroke consultation and approval for iv t - pa , the iv t - pa is infused at the spoke center followed by admission there for observation and stroke work up . this requires a local stroke unit with at least minimal acceptable quality of care with multidisciplinary teams to have an integrative telestroke network . a follow up assessment by a stroke neurologist can also be carried out by telestroke , or through outpatient visit to the hub center a few weeks later . for further complications during the acute phase of treatment , urgent telestroke consultation can be initiated again by the treating physician at the hub hospital . the second method is the ship method , which is recommended for patients with an acute stroke with contraindication for iv t - pa , but that can still have intraarterial t - pa , or an endovascular procedure , and mechanical removal / disruption of the clot ( for example : patients on anti - coagulation with inr > 1.6 ) . here , the patient gets transferred directly to the hub center for urgent treatment and intervention . the third way is drip and ship and indicated for those acute stroke patients who are candidates for iv t - pa . however , the consulting spoke hospital can not provide appropriate post - tpa care or stroke workup . the patient can have the iv t - pa infused locally , and then shipped to the hub center . developing telestroke networks may better encourage more spoke centers to participate if they choose drip and ship since it put less load on the spoke centers , and with time and experience , spoke centers can start admitting patients after thrombolysis . it is also important to mention that the type of clinical practice can be influenced by financial incentives and reimbursements for physicians and hospitals , and by clear job descriptions and duties at each end of the telestroke network , in case of complications or medico - legal claims . the quantity and type of manpower required for a telestroke network varies , and depends on the proposed size of the network , type of clinical operation , and complexity of care . based on experience , each hub center needs 4 or more stroke neurologists , one of them assigned as the medical director of the network , one telestroke manager , one data manager , 2 telestroke nurses , and 2 information technologists , plus the clinical and administrative back up support from the tertiary hospital . for each spoke center , you need to involve at least the emergency physicians , emergency nurses directed by the head of er there , plus a program manager . for drip and keep practice , the multidisciplinary teams including the internists should be added . effective and interactive relationships between different network sites , frequent sites visits between hub and spoke personnel , continuing medical educational activities , and sharing data , and successful stories are mandatory for sustainability and further development . the recommended quality and performance measures for acute stroke units should be used to assess quality and performance of the telestroke networks plus other measures that are specific to telestroke , such as those concerned with communication ( table 1 ) . the director of the telestroke network must obtain the data regularly from each spoke , and hub center , and discuss them at least once annually with all network staff in a transparent fashion with the intention to improve quality and reduce failures . professionals of each telestroke network should also compare their network performance with other networks nationally and internationally . today , most tertiary care hospitals are either practicing some form of telemedicine or considering it soon . the practice can be limited to certain health care networks of similar financial and legal jurisdiction , or may go beyond different states borders . therefore , the first legal issue is getting the license from an appropriate body based on the defined map of telemedicine practice , and making sure the practice does not exceed that map . the second challenge is staff accreditation as different hospitals may have different regulations and requirements . for example in saudi arabia , although the saudi commission for health specialties has a set of regulations concerning staff accreditation to designated positions , tertiary care hospitals like king khalid university hospital have added further requirements . therefore , mutual agreement on staff accreditation between the spoke and hub centers is needed with defined rules and areas of practice , and then hospitals do not need to change their accreditation requirements in order to practice telemedicine . the third challenge is agreement on sharing electronic medical records and patient s data without breaking rules of confidentiality and privacy . this agreement can be initiated by the hospitals boards , but needs to be approved by the appropriate licensing / legal body . as the telestroke network expands and more cases are treated , the hub stroke neurologists may become overwhelmed between their regular hospital duties and telestroke cases , but they will still be legally responsible for delivering the telestroke service on time ; otherwise , they may be blamed for negligence . the director of the telestroke network needs to adequately estimate the required number of stroke neurologists based on the size of the population served , and ensure a fair and stable reimbursement system ; otherwise , staff - recruitment failure may occur . a medical error or failure to serve the acute stroke patient on time can be related to the staff at the spoke center , staff at the hub center , technology related , patient related , or mixed . therefore , a 24/7 documentation and auditing system is needed . the job description of every staff member within the network must be clearly written and defined . regular telestroke morbidity and mortality educational activities must run and be shared between all network sites to enhance the learning curve at different levels as well as discussing successful stories . for example in the usa alone , the direct and indirect costs associated with stroke for 2008 are approximately us$65.5 billion.13 fagan and colleagues14 showed that acute stroke treatment with iv t - pa is associated with an incremental cost savings of us$8,000 per qaly gained , and telestroke was proved to increase thrombolysis rates mainly in patients living in suburban and rural areas.15 there are 2 cost categories associated with telestroke : equipment costs and telestroke running costs , including physician s compensations and salaries for network employees . the annual telestroke hub equipment cost is approximately us$16,204/site , and the annual telestroke spoke equipment costs are approximately us$5,309/site,16 which are cheap when we consider today s medical costs . when looking into the cost - effectiveness of telestroke , we consider the telestroke running costs from one side , which are more or less predictable per network s size , versus the thrombolysis - related savings , such as less or no disability , shorter length of stay at hospital , and savings from less patients transportation . the cost - effectiveness ratio can be non - constant and affected by the network s performance and number of cases treated . too reduce its costs further , it can be part of a synchronous telemedicine network so some resources are shared with other acute medical consultation services . in conclusion , telestroke is the only solution in many countries to serve suburban areas and to increase the thrombolysis rate . new regulations are needed to ensure its legality and stability , and initiatives should come from stroke neurologists , er physicians , and medical directors of small hospitals .

despite developments in acute stroke therapies , stroke continues to be a leading cause of death and disability worldwide . one major limitation from intravenous thrombolysis with tissue plasminogen activator ( t - pa ) is patient s arrival to the emergency room at a tertiary care hospital after the therapeutic time - window , which is generally 270 minutes . the problem is worse for people living in suburban areas where stroke expertise can be missing . therefore , telestroke networks were developed at several sites where a stroke neurologist at a tertiary hospital participates through synchronous audio - video teleconference in confirming diagnosis of stroke , assessing risks and benefits of giving iv t - pa , and making the decision with the patient and emergency physician at the local hospital . in this article , we will review the experience of major telestroke networks in north america and europe , and the evidence of its safety and cost - effectiveness . telestroke complexity , with regard to practice , manpower , quality assurance , and legal issues will be discussed briefly .

in 1974 an influential series of experiments on the microwave - induced multiphoton ionization of highly excited hydrogen atoms was initiated by j. e. bayfield and p. m. koch @xcite . sending a beam of fast hydrogen atoms with principal quantum numbers ranging from @xmath0 to @xmath1 through an x - band microwave cavity and measuring the resulting ionization probabilities as a function of the peak amplitude of the applied oscillating electric field for a frequency of @xmath2 ghz , these authors observed the onset and saturation of ionization with increasing field strength , although , formally , the energy of about 76 microwave photons was required to reach the continuum states from the initial state @xmath3 . remarkably , considerable ionization was observed even when the peak microwave amplitude was small by comparison with the static electric field needed to ionize the atom . it was soon realized that the outcome of these early experiments is well described by a classical approach , based on the evolution of a representative set of classical trajectories in phase space @xcite . since a classical anharmonic oscillator subjected to strong periodic driving naturally gives rise to chaotic dynamics , this inevitably led to the question how the chaotic behavior exhibited by the corresponding classical model is reflected in the ionization process of the real , quantum mechanical hydrogen atom . subsequent theoretical work on this question has led to remarkable insights . on the one hand , casati _ et al . _ have predicted the existence of a certain critical microwave field strength , dubbed quantum delocalization border , above which the quantum wave packet should delocalize , and strong excitation and ionization should take place @xcite . on the other , blmel and smilansky have drawn attention to a qualitative change of the system s floquet states at the ionization border @xcite . significant further interest in the experiments was spurred by the hypothesis , derived from an analysis of the quantum kicked rotator @xcite , that the classical - quantum correspondence might be broken in the high - frequency regime : whereas the energy of chaotic classical trajectories grows diffusively , such diffusive energy growth , and hence ionization , should be suppressed in the quantum system by means of a mechanism closely related to the anderson localization of particles moving on a one - dimensional disordered lattice . indeed , signatures of this high - frequency stabilization have been reported in later works @xcite . moreover , a detailed investigation has been made concerning the influence of classical resonances , and their quantum mechanical counterparts , on the observed ionization signal @xcite . an additional twist to the interpretation of these microwave ionization experiments is provided by the fact that they are _ not _ performed with strictly time - periodic driving : when the fast atoms enter a microwave resonator , they experience a fringe field which , in their rest frame , corresponds to a driving amplitude which increases slowly on the time scale set by one microwave cycle @xcite . this means that the state experimented with within the cavity is actually prepared when entering it : the initial rydberg state can either be shifted adiabatically into the connected floquet state , or undergo multiphoton transitions at avoided crossings of its quasienergy @xcite . in the latter case the precise form of the fringe fields , which translates into the slowly varying envelope of the pulse actually `` seen '' by the atoms , can strongly influence the experimental results . therefore , the question whether or not the actual wave function of the microwave - driven hydrogen atom is able to adiabatically follow the instantaneous floquet states under the action of a pulse provides a key for understanding the ionization data . in the present paper we suggest to transfer these previous single - particle experiments , which have shaped much of our current understanding of periodically driven quantum systems , to the many - body level , utilizing bose - einstein condensates subjected to sinusoidal driving with a smooth , slowly changing envelope . again , the key question then is whether or not the condensate wave function responds to such pulses in an adiabatic manner . as we will argue , there may be far - reaching conceptual analogies between these older microwave experiments and the ones proposed here , with the classical - quantum correspondence being replaced by the correspondence between the mean - field description of a driven condensate and its full many - body dynamics . we proceed as follows : in sec . [ sec:2 ] we review a convenient @xmath4-particle model system , and discuss the results of selected numerical calculations which illustrate its interaction with forcing pulses . in sec . [ sec:3 ] we then compare the @xmath4-particle dynamics to the predictions of a mean - field approach , emphasizing that the latter remains trustworthy only in the regular regime , which allows for adiabatic following of the many - body wave function to the driving amplitude . in the final sec . [ sec:4 ] we formulate our conclusions . our numerical studies are based on the familiar model of a bosonic josephson junction @xcite which supposes that the system consists of two sites connected by a tunneling contact , such that bose particles sitting on the same site repel each other , while interaction between particles on different sites is neglected . thus , the basic part of the model hamiltonian reads @xcite @xmath5 the bosonic operators @xmath6 and @xmath7 , obeying the usual commutation relations @xmath8 = 0 \ ; , \quad \left [ { a^{\dagger}}_j , { a^{\dagger}}_k \right ] = 0 \ ; , \quad \left [ { a^{\phantom{\dagger}}}_j , { a^{\dagger}}_k \right ] = \delta_{jk } \ ; , \ ] ] describe , respectively , the annihilation and creation of a particle at the @xmath9th site ( @xmath10 ) . the tunneling matrix element is written as @xmath11 , so that @xmath12 denotes the single - particle tunneling frequency , while @xmath13 is the repulsion energy contributed by one pair of particles occupying a common site . although the @xmath4-particle ground state of this system ( [ eq : udj ] ) is exactly equal to a coherent state , that is , to an @xmath4-fold occupied single particle state , for vanishing interparticle interaction only , it still remains a highly coherent condensate state even for finite values of the scaled interaction strength @xmath14 this is verified here by computing the one - particle reduced density matrix @xmath15 where the expectation values @xmath16 are taken with respect to the @xmath17th energy eigenstate , from which one obtains the invariant @xmath18 as a measure for the degree of coherence of that eigenstate : a pure condensate state gives @xmath19 , so that @xmath20 , whereas a maximally fractionalized state yields @xmath21 , amounting to @xmath22 @xcite . in fig . [ f_1 ] we depict this degree of coherence for the lowest five eigenstates of a junction ( [ eq : udj ] ) occupied with @xmath23 bose particles . evidently , the ground state @xmath24 remains highly coherent even up to @xmath25 , and thus serves as a good condensate state . many authors have previously studied the dynamics of a bosonic josephson junction ( [ eq : udj ] ) under the action of an external time - periodic force with constant amplitude @xcite . in contrast , in order to monitor the system s adiabatic or non - adiabatic responses to forcing _ pulses _ , and thus to draw the parallels to the microwave ionization experiments reviewed in the introduction , here we introduce a pulse - like , site - diagonal interaction of the form @xmath26 where @xmath27 is the carrier frequency of the pulse , and @xmath28 models its envelope , assumed to be slowly varying on the scale of @xmath29 . in particular , we consider gaussian envelopes @xmath30 with width parameter @xmath31 ; their maximum strength @xmath32 thus carries the dimension of a frequency . the full model given by the total hamiltonian @xmath33 has also been employed in further recent investigations of pulsed many - boson dynamics @xcite . since the dimension of its hilbert space figures merely as @xmath34 when the driven junction hosts @xmath4 bose particles , it allows one to treat fairly large particle numbers with only moderate numerical effort . we now stipulate that initially , at time @xmath35 , the state of the system is given by the numerically determined condensate ground state of the undriven junction ( [ eq : udj ] ) for given , fixed particle number @xmath4 , and integrate the time - dependent schrdinger equation with the hamiltonian ( [ eq : tot ] ) to determine the evolving @xmath4-particle state @xmath36 . here and in the following the reference time scale @xmath37 is given by the carrier cycle time @xmath29 ; in practice , our numerical integrations cover the interval from @xmath38 to @xmath39 . figure [ f_2 ] shows the time - resolved population imbalance @xmath40 of a system comprising @xmath41 particles with scaled interaction strength @xmath42 while interacting with a pulse ( [ eq : pul ] ) equipped with a carrier frequency @xmath43 , moderate maximum strength @xmath44 , and width @xmath45 . although such a pulse actually is comparatively short , so that the variation of the envelope during one single cycle @xmath37 might not appear to be negligible , the system still is responding in an almost perfectly adiabatic manner : adjusting itself to the `` slowly '' changing envelope , here the initial state is transformed almost perfectly into the connected instantaneous floquet state belonging to the current driving amplitude , so that the system is able to return almost completely to its initial state with zero imbalance at the end of the pulse @xcite . if the strength of the pulse is increased , the picture changes : in fig . [ f_3 ] we plot the imbalance for @xmath46 ; all other parameters are the same as before . now the system s response is no longer adiabatic : at the end of the pulse several eigenstates of the junction ( [ eq : udj ] ) are appreciably excited , leading to small , seemingly erratic fluctuations of the imbalance after the pulse is over . in order to quantify this loss of adiabaticity with increasing pulse strength in a more systematic manner , we determine the final occupation probabilities @xmath47 where @xmath48 denotes the eigenstates of the unperturbed system ( [ eq : udj ] ) , and compute the ( dimensionless ) von neumann entropy generated by the pulse according to @xcite @xmath49 since there are @xmath34 different states , the maximum entropy @xmath50 would result if all eigenstates of the junction were populated equally after the pulse , @xmath51 for all @xmath52 . the normalized entropy @xmath53 therefore varies between zero and unity , with values close to unity indicating almost equal distribution of the final state over the unperturbed energy eigenstates . in fig . [ f_4 ] we depict the logarithm of this normalized final entropy vs. the scaled maximum driving amplitude @xmath54 , again for @xmath41 , @xmath42 , and @xmath43 . here we also consider several different pulse widths , @xmath55 , @xmath56 , @xmath57 , @xmath58 , and @xmath59 , thereby allowing for a varying degree of adiabaticity . except for the shortest pulses with @xmath55 all curves almost coalesce , giving a quite consistent picture : pulses with maximum scaled amplitude lower than @xmath60 enable adiabatic following , and thus result in negligible entropy production . then there is a transition regime , extending from @xmath60 to about @xmath61 , in which a slight increase of the maximum amplitude triggers a steep rise of the entropy . for still stronger pulses one observes close - to - maximum entropy generation , corresponding to a significant heating of the initial condensate . in figs . [ f_5 ] and [ f_6 ] we repeat these investigations for @xmath62 and @xmath23 particles , respectively , keeping the scaled interaction strength @xmath42 fixed , so that an increase of the particle number @xmath4 is accompanied by a reduction of the bare interparticle interaction strength @xmath63 @xcite . again one observes an adiabatic regime and a regime of close - to - maximum entropy production , separated by a transition regime , but there is an additional feature : with these larger particle numbers the system is able to discern the different pulse widths , meaning that the onset of entropy production shifts to higher maximum amplitudes when the pulse is made longer . on the other hand , the onset of the regime of maximum heating appears to be more or less independent of the pulses length . these numerical findings bear a striking similarity to the microwave ionization experiments @xcite referred to in the introduction : there one finds a `` delocalization border '' @xcite above which a microwave pulse leads to significant ionization of a highly excited hydrogen atom ; here one observes a `` heating border '' above which a driving pulse leads to significant entropy generation in the model defined by the hamiltonian ( [ eq : tot ] ) . this model may be somewhat simple , and not capture all aspects of the exact many - body dynamics of experimentally feasible driven bosonic josephson junctions . nonetheless , we surmise that its main constitutive element , the existence of a heating border , is a generic feature of pulsed bose - einstein condensates also in typical experimental configurations which do not lend themselves to exact numerical many - body calculations . within a mean field - type approach the dynamics of bose - einstein condensates are described by the time - dependent nonlinear gross - pitaevskii equation for the condensate s macroscopic wave function @xcite . in the case of the driven two - site system governed by the hamiltonian ( [ eq : tot ] ) this equation is cast into the form @xcite @xmath64 where @xmath65 is a dimensionless time variable , and @xmath66 denotes the scaled interparticle interaction strength already employed in the previous section . the squared amplitudes @xmath67 are to be interpreted as the expected fraction of particles occupying the @xmath9th site at time @xmath68 ( @xmath69 ) . a detailed derivation @xcite of these coupled nonlinear equations ( [ eq : gpe ] ) which is not based on a coherent - states approach , but rather compares the evolution of an @xmath4-particle system to that of subsidiary systems obtained by the removal of one particle , reveals that they indeed do provide a faithful image of the exact @xmath4-particle dynamics generated by the hamiltonian ( [ eq : tot ] ) in the limit of large @xmath4 , provided their solutions remain _ regular_. in this case the dynamics in fock space are stiff , in the sense that the subsidiary @xmath70-particle states remain closely related to the actual @xmath4-particle state while evolving in time . if , however , the solutions to eqs . ( [ eq : gpe ] ) become _ chaotic _ , their direct link to the @xmath4-particle level is lost : in that latter case the exact @xmath4-particle state , when responding to the external drive , acquires a level of complexity which amounts to a destruction of the macroscopic wave function , so that its description in terms of a gross - pitaevskii approach becomes pointless @xcite . we now consider the initial condition @xmath71 as corresponding to the condensate ground state @xmath72 of the undriven junction ( [ eq : udj ] ) , and utilize the gross - pitaevskii equation ( [ eq : gpe ] ) for computing the mean - field return probabilities @xmath73 for the same pulses as studied before . in fig . [ f_7 ] we display such mean - field return probabilities for short and long pulses , @xmath55 ( upper panel ) and @xmath74 ( lower panel ) , in comparison with the corresponding full @xmath4-particle quantum return probabilities @xmath75 obtained for @xmath23 . for the shorter pulses the gross - pitaevskii treatment slightly overestimates the `` critical '' maximum amplitude @xmath54 at which the sudden drop of the @xmath4-particle return probability indicates the loss of adiabaticity , in line with a substantial entropy production . for the longer pulses , which should favor adiabatic motion , the onset of a chaotic mean - field return pattern agrees very well with the quantum heating border . we conclude that the comparatively simple gross - pitaevskii equation , although it is lacking theoretical justification in the entropy - generation regime where no macroscopic wave function exists , is quite capable of determining the heating border itself . the field of `` quantum chaos '' , which by now has led to a deepened understanding not only of the classical - quantum correspondence , but also of generic quantum dynamics itself , has previously concentrated on single - particle systems , chosen to be sufficiently simple to allow for full - fledged numerical analysis on both the classical and the quantum level @xcite . externally driven bose - einstein condensates now offer attractive prospects for extending these developments to an even more challenging many - body context . as long as such condensates respond to the drive in a `` regular '' manner , their macroscopic wave function remains preserved , possibly corresponding to a macroscopically occupied single - particle floquet state . if , however , one encounters the realm of `` chaotic '' dynamics , the many - body state no longer remains entropyless , but necessarily has to carry a lot of information , and therefore to acquire a high level of complexity which is not accessible to a mean - field ansatz . the mean - field dynamics associated with a periodically driven bosonic two - mode josephson junction ( [ eq : udj ] ) are exactly equivalent to those of a driven nonlinear classical pendulum @xcite . therefore , in this exceptional case one may approach chaotic many - body dynamics by mapping out the corresponding classical phase space , as done in a recent experiment reported by tomkovi _ _ @xcite . however , in more general cases a reduction to two - mode dynamics will not be feasible , and more versatile tools of investigation will be required . then the concept of adiabatic following of driven many - body states to the respective instantaneous floquet states , as explored in the context of `` avoided - level - crossing spectroscopy '' for driven bose - hubbard - like systems @xcite , suggests itself : adiabatic following of a bose - einstein condensate to a smooth forcing pulse amounts to the preservation of an entropyless condensate state which can exist in the regular regime only , whereas the entropy production associated with the loss of adiabaticity signals the onset of chaos . thus , it should be a worthwhile enterprise to set up an experiment for investigating the transition from regular , mean field - like condensate dynamics to chaotic many - body dynamics in systematic detail along the lines suggested in the present proposal : start from a bose - einstein condensate in a trapping configuration which allows for the application of well - defined forcing pulses . then subject the condensate to a pulse with a slowly varying , smooth envelope , and measure the coherence of the final state after the pulse by recording , _ e.g. _ , the condensate fraction through time - of - flight absorption imaging . as long as the maximum pulse strength does not reach the chaotic regime , the system s response should be adiabatic . thus , the condensate will return almost fully to its initial state after the pulse , with negligible production of entropy . if , however , the driving amplitude crosses the border to chaos , adiabatic following is disabled , and the system undergoes manifold excitations during the pulse , corresponding to a high entropy production . such dynamical heating of the condensate leads to its destruction , detectable after the pulse through the loss of coherence . therefore , in configurations possessing a sharp chaos border , which may be achievable with anharmonic trapping potentials , one should observe a sharp drop of the final coherence when the maximum driving amplitude is gradually increased . from a theoretician s perspective , the difference between `` regular '' and `` chaotic '' dynamics of periodically driven quantum systems is reflected in the properties of their quasienergy spectra when these are considered for all instantaneous driving amplitudes encountered during the pulses , with smooth coarse - grained quasienergy eigenvalues in the regular regime enabling effectively adiabatic following of the corresponding floquet states , whereas multiple avoided quasienergy crossings in the chaotic regime give rise to multiphoton - like landau - zener transitions effectuating the observed entropy growth @xcite . while the numerical computation of such quasienergy spectra , and the verification of adiabatic following of many - body floquet states , is still feasible for simplified models such as the driven josephson junction considered here @xcite , this goal will remain unachievable for realistic mesoscopic condensates consisting of @xmath76 particles , say . hence , the experiments suggested in this work might break new ground in an area where numerical guidance is feasible on the mean - field level only : the question whether the educated guesses derived from the present model study actually hold water for very large @xmath4 has to be decided in the laboratory . such condensate experiments would constitute a natural extension of previous microwave ionization experiments with highly excited hydrogen atoms @xcite , in which a classical chaos border manifests itself through the onset of strong ionization . while that ionization border would find its match in the heating border discussed here , the question whether driven condensates may also give rise to an analog of the anderson - like suppression of classical phase - space diffusion reported for the quantum kicked rotator @xcite appears to be open . we are grateful for cpu time granted to us on the hpc cluster hero , located at the university of oldenburg and funded by the dfg through its major research instrumentation programme ( inst 184/108 - 1 fugg ) , and by the ministry of science and culture ( mwk ) of the lower saxony state .

we suggest to subject anharmonically trapped bose - einstein condensates to sinusoidal forcing with a smooth , slowly changing envelope , and to measure the coherence of the system after such pulses . in a series of measurements with successively increased maximum forcing strength one then expects an adiabatic return of the condensate to its initial state as long as the pulses remain sufficiently weak . in contrast , once the maximum driving amplitude exceeds a certain critical value there should be a drastic loss of coherence , reflecting significant heating induced by the pulse . this predicted experimental signature is traced to the loss of an effective adiabatic invariant , and to the ensuing breakdown of adiabatic motion of the system s floquet state when the many - body dynamics become chaotic . our scenario is illustrated with the help of a two - site model of a forced bosonic josephson junction , but should also hold for other , experimentally accessible configurations .

diabetes is now commonly recognized as a coronary heart disease risk equivalent [ 14 ] . this is mainly attributed to the high rates of dyslipidemia among diabetic patients which is believed to be one of the major factors accounting for the high percentage of deaths among diabetics due to cardiovascular disease ( cvd ) . the differences in the lipid profile between diabetics ( especially type 2 diabetics ) and nondiabetics account for the increased cvd risk . essentially , t2 dm lipid profiles consist of elevations in triglyceride ( tg ) levels ( > 2 mmol / l ) and reductions in high - density lipoprotein cholesterol ( hdl - c ) . while low - density lipoproteins cholesterol ( ldl - c ) concentration levels are normal , the particles are denser and smaller in size , which is believed to enhance their atherogenic potential . numerous epidemiological studies and randomized controlled trials have documented the association between elevated ldl - c levels with increased cvd risk in both diabetic and nondiabetic populations [ 8 , 9 ] . thus reducing ldl - c levels is the primary goal of therapy for diabetic dyslipidemia [ 5 , 10 ] . on the other hand , raising hdl - c and reducing triglycerides have been associated with moderate reductions in cvd risk and are thus regarded as of secondary importance . lowering of ldl - c levels is thought to be the main beneficial effect of statin treatment ; although , effects on hdl - c and other lipoproteins also play a role . there are currently seven approved statins which are commonly prescribed , and each has a different benefit - risk profile . to date , numerous randomized trials among various ethnicities have documented that rosuvastatin is the most effective statin at reducing ldl - c and triglycerides ( tg ) and at raising hdl - c levels [ 14 , 15 ] . atorvastatin , on the other hand , was previously , before the approval of rosuvastatin , documented to be the most potent statin at reducing ldl - c levels . alternatively , pravastatin which is available at the higher doses of 20 mg and 40 mg is found to be slightly less effective ; the main reason for its prescription in patients is put down to its hydrophilic properties which make it more tolerable to patients with greater risk factors in addition to cvd . the muscular system , hepatic function , and renal function have been documented to be affected by statin treatment [ 18 , 19 ] . in general , large - scale randomized clinical trials have consistently demonstrated that statin therapy causes only a slight increased risk of side effects compared with placebo [ 20 , 21 ] . for instance , postmarketing data report an overall adverse event frequency of less than 0.5% and a myotoxicity event rate of less than 0.1% . in qatar , there are currently no guidelines available for treating diabetic patients with dyslipidemia , and no previous study has documented the efficacy and safety of the various statins prescribed to diabetic patients . thus the current study aims to build on this growing awareness of atherosclerosis - specific care of diabetes patients , by examining efficacy and safety of the three most commonly prescribed statins in the state of qatar . this retrospective observational population - based study was conducted in hamad general hospital , hamad medical corporation which is the main tertiary hospital in qatar serving , over 90% of the population of qatar . the study population was drawn from consecutive diabetic patients who presented to hamad general hospital with dyslipidemia and were prescribed the indicated statins and underwent fasting blood test of lipid profile before statin treatment initiation between september 2005 and september 2009 . the diagnosis and when to treat dyslipidemia in diabetics in hamad general hospital are established on the basis of who expert group criteria ; the who recommends screening for lipid disorders at least annually in diabetic patients and more often if needed to achieve goals . on the other hand , adults with low - risk lipid values ( ldl - c < 100 mg / dl [ 2.6 mmol / l ] , hdl - c > 50 mg / dl [ 1.3 mmol / l ] , and triglycerides < 150 mg / dl [ 1.7 mmol / l ] ) may be screened every two years . the inclusion criteria included diabetic patients ( fasting blood glucose 126 mg / dl [ 7.0 mmol / l ] ) who were prescribed any of the indicated statins ( rosuvastatin , atorvastatin , pravastatin ) during 20052009 ( 2 years within this period ) to ensure at least 2 years of using the statin , aged 18 years , and had a total cholesterol level of 4 mmol / l , ldl - c 2.5 mmol / l , hdl - c 1 mmol / l in men and 1.2 mmol / l in women , and fasting triglycerides 1.7 mmol / l , obtained within 1 week before the first use of statins which will be then compared at first- and second - year intervals . this study excluded pregnant women ; patients with genetic disorders ; patients on other concurrent lipid lowering agents such as bile acid sequestrants ( cholestyramine , colesevelam ) , niacin , ezetimibe , fenofibrate and/or omega 3 ; patients with previous history of angina , severe vascular disease , or other life threatening disease ; patients with nephropathy and/or hypothyroidism , active liver disease , bile duct problems , or alt > 3 uln ; patients with creatine kinase levels > 10 uln ; patients taking concurrent corticosteroids , ciclosporin , and/or hormone replacement therapy ; patients who are physically inactive ; patients with a history of drug or alcohol abuse . irb ethical approval , for this study , was obtained from medical research committee of hamad medical corporation prior to commencement of data collection . patients were identified as statin users ( rosuvastatin , atorvastatin , pravastatin ) during the study period ( september 2005september 2009 ) by using the pharmacy database . fifty patients were included in the study for each statin dose , and these had to have been on the same dose for at least 2 years between the periods indicated previously . the data for these patients were obtained from 2 sources which are the electronic medical database called ( emr viewer ) and the patients ' files from the medical records department of hamad medical corporation ( hmc ) . the prescribed doses in hmc for diabetic patients with dyslipidemia are as follows : rosuvastatin 10 mg and 20 mg , pravastatin 20 mg and 40 mg , atorvastatin 10 mg , 20 mg , and 40 mg . rosuvastatin 10 mg and 20 mg , pravastatin 20 mg and 40 mg , atorvastatin 10 mg , 20 mg , and 40 mg . patients had been checked 3 times to exclude duplications which finally resulted in a total sample of 350 patients . the measures consisted of questions relating to sociodemographic data , medical history , and comorbid factors , lifestyle habits , lab investigations , and patient 's antihypertensive medications ( arbs and/or ace inhibitors ) . thereafter , any discrepancies found between the data collection sheet and the data available in the medical record were resolved . the first part included the type of statin prescribed for the patient for at least 2 years continuously and dose of statin . the second part included information about sociodemographic characteristics including age , sex , nationality , height , weight , and bmi . the third section collected information about type of dm , its duration , and presence of hypertension . the fourth section included items about laboratory investigations such as fasting blood glucose , glycated hemoglobin ( hba1c ) , total cholesterol , hdl and ldl cholesterol levels , triglycerides , creatine kinase level , serum creatinine , bilirubin , lfts , ggt , and serum albumin and adverse events like microalbuminuria and macroalbuminuria . finally the fifth section included the initiation of antihypertensive medications ( arbs and/or ace inhibitors ) . student 's t - test was used to ascertain the significance of differences between mean values of two continuous variables and confirmed by nonparametric mann - whitney test . in addition , paired t - test was used to determine the difference between baseline and 2 years after regarding biochemistry parameters , and this is confirmed by the wilcoxon test which is a nonparametric test that compares two paired groups . chi - square and fisher exact tests were performed to test for differences in proportions of categorical variables between two or more groups . the level p < 0.05 was considered as the cutoff value or significance . the majority of patients were qatari , had a bmi > 30 kg / m , and had comorbid hypertension . table 2 and figures 1 and 2 show the comparison of the efficacy of each statin at each dose ( 10 mg , 20 mg , and 40 mg ) . rosuvastatin ( 10 mg and 20 mg ) was the most effective at reducing ldl - c ( 29.03% and 29.3% , resp . ) . atorvastatin reduced ldl - c the most at a dose of 40 mg ( 22.8% ) , and pravastatin reduced ldl - c the most at a dose of 20 mg ( 20.3% ) . moreover , rosuvastatin ( 10 mg ) reduced triglycerides the most ( 25.1% , p < 0.01 ) . this was the case , even in comparison to higher doses of rosuvastatin ( 20 mg ) and to higher doses of atorvastatin ( 20 mg and 40 mg ) and pravastatin ( 20 mg and 40 mg ) . finally , all of the statins appear to have reduced rather than raised hdl - c levels . figure 3 presents the percentage of patients with the new onset of microalbuminuria after taking statins . atorvastatin was the safest statin as it resulted in the least number of patients at the end of 2 years of treatment with the new onset of microalbuminuria ( 10.9% ) followed by rosuvastatin ( 14.3% ) and then pravastatin ( 26.6% ) . table 3 presents an overview of the safety profile of each of the statins at their various doses among patients . statins appear to be safe in relation to hepatic and muscular functions as no patients presented with alt > 3 uln or ck > 10 uln . a slightly adverse effect of statins on renal function was observed due to the new onset of microalbuminuria among some of the patients ; nonetheless no case of microalbuminuria progressed to the more dangerous macroalbuminuria . in the present study , rosuvastatin ( 10 mg and 20 mg ) was found to be the most effective statin at reducing ldl - c when compared with atorvastatin ( 10 mg , 20 mg , and 40 mg ) and pravastatin ( 20 mg and 40 mg ) . in other words , rosuvastatin at its lowest dose in this study ( 10 mg ) was more effective at reducing ldl - c levels than atorvastatin and pravastatin at their highest doses ( 40 mg ) . indeed , it should be noted that rosuvastatin , which is the latest statin to receive approved labeling by the food and drug administration , has been consistently found to be the most effective at reducing ldl - c levels in the most recent studies comparing its efficacy to other statins . our results are consistent with stellar trial which is one of the major open - label , randomized , and multicenter trials to compare rosuvastatin ( 10 , 20 , 40 , or 80 mg ) with atorvastatin ( 10 , 20 , 40 , or 80 mg ) , pravastatin ( 10 , 20 , or 40 mg ) , and simvastatin ( 10 , 20 , 40 , or 80 mg ) across dose ranges for reduction of ldl - c . the results of the stellar trial revealed that rosuvastatin was consistently , across all doses , the most effective at reducing ldl - c levels in comparison to all of the other statins . the lowering of triglycerides is another important goal in reducing cvd risk among diabetic patients . in the current study , the greatest reduction in triglycerides was ( 25.1% , p < 0.01 ) and was achieved by patients taking rosuvastatin ( 10 mg ) . this was the case , even in comparison to higher doses of rosuvastatin ( 20 mg ) and to higher doses of atorvastatin ( 20 mg and 40 mg ) and pravastatin ( 20 mg and 40 mg ) . however , it is important to note that atorvastatin ( 10 mg and 40 mg ) both achieved the second highest reduction in triglycerides ( 21.05% , p < 0.05 , and 21.56% , p = ns ) , respectively . these findings are similar to the majority of studies in the literature , which have shown a slightly higher reduction in triglycerides in patients taking rosuvastatin in comparison to atorvastatin . it thus appears that , in relation to this factor ( triglycerides ) , that both rosuvastatin and atorvastatin are effective at reducing it . raising hdl - c levels is another major factor known to reduce cvd risk [ 11 , 27 ] . in the current study , all of the statins appear to have reduced rather than raised hdl - c levels . rosuvastatin ( 20 mg ) had the least reduction of ( 4.0% ) and would thus be regarded as the most effective ; however , none of the values for the statins were significant . in this instance , the findings in the current study are contrary to the studies in the literature . for example , the stellar trial found rosuvastatin ( 40 mg ) to be the most effective on increasing hdl - c . in fact it is noted that across dose ranges , the hdl cholesterol increasing effect of rosuvastatin was consistent across the dose range and was significantly higher ( p < 0.001 ) compared with those of simvastatin and pravastatin . as for the pulsar study which investigated starting doses of rosuvastatin and atorvastatin , they found that the increase in hdl - c was significantly greater statistically with rosuvastatin ( 10 mg ) than with atorvastatin ( 20 mg ) . a number of factors could be at play which could explain the discrepancy between the current study 's results and those in the international literature . it is evident from table 1 which has the patient characteristics that many of the patients had more than two risk factors for cvd . for instance , the patients were diabetic , and most of them were over 55 years old and had hypertension . in other diabetic research studies conducted in qatar , it was found that having qatari ethnicity was correlated with poor lifestyle habits such as sedentary lifestyle and poor eating choices [ 2 , 3 ] . in other words , the subjects had so many other factors which caused their hdl - c levels to be so low that the statins were only able to have a minimal effect . one of the most common complaints related to statin use is related to the effect of statins on muscular function . muscle symptoms range from myalgia , which includes muscle pain without creatine kinase ( ck ) elevations , to myositis which is muscle symptoms with ck elevations . in general , elevations of ck of more than ten times the upper limit of normal are regarded as significant elevations justifying the discontinuation of statin treatment . in the current study in other words , all statins , irrespective of dose , were regarded as safe in terms of myositis . this is mainly measured by asymptomatic elevations of the liver enzymes alt and ast , otherwise known as transaminitis . in the current study , no patients had elevated alt > 3 upper limit of normal . thus there were no adverse events related to hepatic function reported with the use of any of the statins in the study . this is not surprising , as clinical trials have reported a 0.53.0% occurrence of elevations in aminotransferases among patients receiving statins and very rare episodes of severe liver injury . in general , the incidence of hepatic failure in patients taking statins appears to be in different from that in the general population . in the current study , the three statins ( atorvastatin 10 , 20 , and 40 mg ; rosuvastatin 10 and 20 mg ; and pravastatin 20 and 40 mg ) with different doses did not significantly affect the serum creatinine and gfr after 2 years . in addition , the three statins appeared to be relatively safe for patients with microalbuminuria at baseline , as the number of those whose microalbuminuria increased was very minimal . in fact , pravastatin ( 40 mg ) appeared to reduce the number of patients with baseline microalbuminuria . on the other hand , in patients without baseline microalbuminuria , there appeared to be relatively significant onset of microalbuminuria in patients taking pravastatin ( 26.6% ) and to a lesser degree rosuvastatin ( 14.3% ) and atorvastatin ( 10.9% ) . while some statin trials have reported a reduction in proteinuria or no effect , some of the literature supports the findings in the current study that statins do have negative effects relating to the onset of proteinuria . the main reason stated for atorvastatins ' safety in relation to renal function is its somewhat unique method of metabolism ; in that it has the least degree of renal excretion ( 2% ) , followed by fluvastatin ( 5% ) , rosuvastatin ( 10% ) , lovastatin ( 10% ) , simvastatin ( 13% ) , and pravastatin ( 20% ) . the results obtained in the current study have shown that rosuvastatin is the most effective statin at reducing ldl - c , triglycerides , and total cholesterol , at the lowest dose ( 10 mg ) . moreover , it reduced hdl - c the least in comparison to the other statins . thus in the qatari diabetic dyslipidemic population it appears to be the most effective statin . in addition , this study provides a good base for future large - scale prospective studies to be conducted on the topic .

objectives . to investigate the efficacy and the safety of the three most commonly prescribed statins ( rosuvastatin , atorvastatin , and pravastatin ) for managing dyslipidemia among diabetic patients in qatar . subjects and methods . this retrospective observational population - based study included 350 consecutive diabetes patients who were diagnosed with dyslipidemia and prescribed any of the indicated statins between september 2005 and september 2009 . data was collected by review of the pharmacy database , the electronic medical records database ( emr viewer ) , and the patient 's medical records . comparisons of lipid profile measurements at baseline and at first- and second - year intervals were taken . results . rosuvastatin ( 10 mg ) was the most effective at reducing ldl - c ( 29.03% ) . atorvastatin reduced ldl - c the most at a dose of 40 mg ( 22.8% ) , and pravastatin reduced ldl - c the most at a dose of 20 mg ( 20.3% ) . all three statins were safe in relation to muscular and hepatic functions . in relation to renal function , atorvastatin was the safest statin as it resulted in the least number of patients at the end of 2 years of treatment with the new onset of microalbuminuria ( 10.9% ) followed by rosuvastatin ( 14.3% ) and then pravastatin ( 26.6% ) . conclusion . in the qatari context , the most effective statin at reducing ldl - c was rosuvastatin 10 mg . atorvastatin was the safest statin in relation to renal function . future large - scale prospective studies are needed to confirm these results .

the cern large hadron collider ( lhc ) and the upcoming international linear collider ( ilc ) are expected to perform precision tests of the standard model ( sm ) and explore the new physics at the tev scale @xcite . the large extra dimensions ( led ) model is one of the scenarios beyond the sm which are proposed to solve the hierarchy problem @xcite . the led model has only one fundamental scale , @xmath5 tev , and it may induce predictable collider phenomena at both the lhc and the ilc . up to now , many works on both the virtual kaluza - klein ( kk ) graviton exchange and the real kk - graviton production have been presented ; for example , the @xmath6 and @xmath7 processes were studied in the led model in refs.@xcite-@xcite . in fact , the triple gauge boson ( tgb ) production processes are sensitive to the quartic gauge couplings ( qgcs ) and thus related to the electroweak symmetry breaking mechanism @xcite . any deviation from the sm prediction hints at the existence of new physics , such as the higgsless or extra dimension signals @xcite . in discriminating physics beyond the sm , we should investigate the potential contributions from the extension models . compared with the thoroughly studied diboson production processes in extra dimension models , the tgb productions have been fully studied in the sm @xcite but gained less attention in the led model . not long ago , the neutral tgb production processes at the lhc , @xmath8 , @xmath9 , @xmath10 and @xmath11 , were studied in the framework of the led model in ref.@xcite . in this paper , we investigate the possible contributions of the virtual kk - graviton exchange to the @xmath12 and @xmath13 productions at both the lhc and ilc . the motivation for this work is shown in two fields : firstly , the @xmath12 and @xmath13 processes are directly related to the sm qgcs , namely @xmath14 , @xmath15 and @xmath16 , which are different from the absence of the neutral qgcs in the sm at the tree level @xcite . secondly , although the experimental precision is limited by our understanding of strong qcd background , the lhc can provide more precision measurements of the qgcs than the existing data from lep ii and tevatron searches due to its very high energy and luminosity @xcite . furthermore , in the future , the qgcs can be further probed with higher precision at the ilc due to its cleaner environment @xcite . in this sense , the lhc and the upcoming ilc will provide complementary studies on the tgb production channels . the paper is organized as follows : in section ii , we present the related theory of the led model used in our calculations . in section iii , the calculation strategies are presented . the numerical results and analyses for the @xmath12 and @xmath13 production processes at both colliders are provided in section iv , and a short summary is given in the last section . in the led model @xcite , the spacetime is @xmath17 with @xmath18 being the number of extra dimensions . the only fundamental scale @xmath19 unifying the gravity and the gauge interactions is at the tev . to explore the phenomenological effects , one can extract the low - energy effective theory by the kk reduction in the brane - bulk picture @xcite . in this scenario , the sm particles are confined on a @xmath20-dimensional brane world volume while the gravity can propagate in the @xmath21-dimensional bulk . after the assumed torus compactification of the extra dimensions @xmath18 , the usual planck scale @xmath22 in the @xmath20 spacetime is related to the fundamental scale @xmath19 as @xmath23 @xcite , where @xmath24 is the radius of the @xmath18 torus . in the following calculations , we adopt the de donder gauge for the kk - graviton part , while the feynman gauge ( @xmath25 ) is used for the sm part . we assume all the momenta flow to the vertices , except that the fermionic momenta are set to be along with the fermion flow directions . then we list the feynman rules for the relevant vertices and the propagator of spin-2 kk - graviton in the led model below @xcite , where @xmath26 , @xmath27 , @xmath28 , @xmath29 and @xmath30 represent the fields of the graviton , fermion , @xmath31 boson , @xmath32 boson and photon , respectively . * @xmath33 @xmath34\end{aligned}\ ] ] * @xmath35 @xmath36 * @xmath37 @xmath38\end{aligned}\ ] ] * @xmath39 @xmath40\end{aligned}\ ] ] * @xmath41 @xmath42\end{aligned}\ ] ] * @xmath43 @xmath44\end{aligned}\ ] ] where @xmath45 , @xmath46 is the fine - structure constant , @xmath47 is the electric charge of fermion , @xmath48 are sine ( cosine ) of the weinberg angle , the vector and axial vector couplings of the @xmath32-boson , i.e. , @xmath49 and @xmath50 , are the same as in the sm , and @xmath51 is related to the reduced planck mass as @xmath52 , where @xmath53 is the newton constant . the tensor coefficients @xmath54 , @xmath55 and @xmath56 are expressed as @xcite @xmath57 , { \nonumber}\\ e^{\mu \nu \rho \sigma}(k_{1},k_{2 } ) & = & \eta^{\mu \nu}(k_1^{\rho } k_1^{\sigma } + k_2^{\rho } k_2^{\sigma } + k_1^{\rho } k_2^{\sigma } ) - \left [ \eta^{\nu \sigma } k_1^{\mu } k_1^{\rho } + \eta^{\nu \rho } k_2^{\mu } k_2^{\sigma } + ( \mu \leftrightarrow \nu)\right ] . { \nonumber}\end{aligned}\ ] ] after summation over kk states the spin-2 kk - graviton propagator can be expressed as @xcite @xmath58,\end{aligned}\ ] ] where @xmath59,\ ] ] and @xmath60 the integral @xmath61 contains an ultraviolet cutoff @xmath62 on the kk modes @xcite . it should be understood that the point @xmath63 has been removed from the integration path , and we set the ultraviolet cutoff @xmath62 to be the fundamental scale @xmath19 routinely . the real part proportional to @xmath64 in eq.([res ] ) is from the narrow resonant production of a single kk mode with @xmath65 and the imaginary part @xmath66 is from the summation over the many nonresonant states . the @xmath12 and @xmath13 productions at the lhc arise form the quark - antiquark annihilation and the gluon - gluon fusion subprocesses at the parton level : @xmath67 the @xmath68 processes at the ilc can be denoted as @xmath69 in reactions ( [ channel-1 ] ) , ( [ channel-2 ] ) and ( [ channel-3 ] ) , @xmath70 , and @xmath71 @xmath72 represent the four - momenta of initial and final particles . the leading order ( lo ) feynman diagrams with kk - graviton exchange for ( [ channel-1 ] ) and ( [ channel-2 ] ) channels are shown in figs.[fig1 ] and [ fig2 ] , respectively , while the lo additional feynman diagrams in the led model for the process ( [ channel-3 ] ) are depicted in fig.[fig3 ] . from these feynman diagrams , one can find that the kk - graviton couples not only to the fermion pair , vector boson pair , and fermion - antifermion - vector boson ( @xmath73 ) , but also to the tgb including charged gauge boson , which is absent in the neutral tgb production processes as shown in ref.@xcite . therefore , it is natural to expect that kk - graviton in the led model may induce considerable effects at the tev scale on the tgb production processes concerning charged gauge bosons at the lhc and the future ilc . we express the feynman amplitudes for the partonic processes @xmath74 and @xmath75 as @xmath76 where @xmath77 @xmath78 is the amplitude contributed by the sm - like diagrams , while @xmath79 and @xmath80 are the amplitudes with kk - graviton exchange . the feynman amplitude for the @xmath81 process can be expressed as @xmath82 where @xmath83 stands for the amplitude mediated by the sm - like particles , while @xmath84 is mediated by the kk - graviton . the total cross sections for the partonic process @xmath85 can be expressed as @xmath86 where @xmath87 is the three - momentum of one initial parton in the center - of - mass system ( c.m.s ) , the summation is taken over the spins or colors of initial and final particles , the prime on the sum recalls averaging over initial spins or colors , and @xmath88 is the three - body phase space element expressed as @xmath89 by convoluting @xmath90 with the parton distribution functions ( pdfs ) of the colliding protons , the total cross section for the @xmath91 parent process can be written as @xmath92 , { \nonumber}\\\end{aligned}\ ] ] where @xmath93 @xmath94 represents the pdf of parton @xmath95 in proton @xmath96 , @xmath97 is the factorization scale , @xmath98 and @xmath99 describe the momentum fractions of parton ( quark or gluon ) in protons @xmath100 and @xmath101 , respectively . the expression for the total cross section for @xmath81 is @xmath102 where @xmath87 is the three - momentum of the incoming @xmath103 ( or @xmath104 ) in the c.m.s of @xmath105 collider . the prime on the sum means averaging over initial spin states as declared for eq.([int - ppvvv ] ) . in this section , we present the numerical results in both the sm and the led model at the lhc and ilc . for the calculations at the lhc , we use the cteq6l1 pdfs @xcite with @xmath106 and @xmath107 ; the factorization scale is set to be @xmath108 and @xmath109 for the @xmath110 and @xmath111 processes , respectively . the active quarks are taken as massless , i.e. , @xmath112 , the ckm matrix is set to be the unit matrix . the other related input parameters are taken as @xcite @xmath113 since the led model is an effective low - energy theory , it breaks down in the non - perturbative region where @xmath114 or above . in order to make reliable and viable phenomenological predictions , we take the hard and conservative truncation scheme as setting the cut @xmath115 for proton - proton collision and the limit @xmath116 tev @xmath117 for the @xmath105 collision , where @xmath118 and @xmath119 are the partonic and @xmath103-@xmath104 c.m.s energies , respectively . in evaluating the @xmath120 processes , we put a transverse momentum cut @xmath121 gev and a rapidity cut @xmath122 on the final photon in order to get rid of the ir singularity at the tree level . recently , the led parameters @xmath123 and @xmath18 have obtained more severe constraints by the lhc experiments . the atlas collaboration provided @xmath124 confidence level lower limits on @xmath123 in the range of @xmath125 tev depending on the number of extra dimensions @xmath18 in the range of @xmath126 to @xmath127 @xcite . the diphoton searches at cms set @xmath128 tev @xmath129 tev @xcite , and the dilepton experiments at cms set the limit on @xmath123 as @xmath130 tev @xmath131 tev with the number of extra dimensions @xmath18 varying from @xmath126 to @xmath127 at @xmath124 confidence level @xcite . in our calculations we take @xmath132 tev and @xmath133 unless otherwise stated . for the verification of the correctness of our numerical calculations , we use both the feynarts 3.5 @xcite and comphep 4.5.1 @xcite packages to calculate the integrated cross sections for the @xmath134 and @xmath91 processes at the @xmath135 gev ilc and the @xmath136 tev lhc in the sm separately . we take the input parameters , pdfs , and the event selection criteria as mentioned above . the numerical results are listed in table [ tab1 ] . it demonstrates that the results from the two packages are in good agreement within the calculation errors . . [ tab1 ] the integrated cross sections for the processes @xmath137 and @xmath91 in the sm at the @xmath135 gev ilc and the @xmath136 tev lhc by using feynarts 3.5 @xcite and comphep 4.5.1 @xcite packages separately . [ cols="^,^,^",options="header " , ] in this paper , we study the led effects induced by the virtual kk - graviton on the @xmath3 and @xmath4 production processes at both the lhc and ilc . the comparison between the results for these productions at both colliders are made . we present the transverse momentum and rapidity distributions of final particles , and find that the led contributions remarkably affect the observables of these processes , particularly in either the high transverse momentum region or the central rapidity region ( @xmath138 ) . we see that the relative led discrepancy becomes larger with the increment of the invariant mass of final @xmath31 pair , and the integrated cross section in the led model decreases when @xmath19 goes up for a fixed @xmath18 at both the ilc and lhc . the @xmath139 discovery and @xmath140 exclusion limits on the fundamental scale @xmath19 are also obtained at both the ilc and lhc . we also find that the relative led discrepancy for the @xmath0 production at the lhc is generally larger than that at the ilc due to the additional led contributions via @xmath1 fusion subprocesses and the kk - graviton exchanging resonant effect induced by the continues large colliding energy available in the lhc . from the aspect of effectively exploring the led signal in measuring @xmath0 production , we conclude that the @xmath3 and @xmath4 productions at the lhc could have the distinct advantage over at the ilc . * acknowledgments : * this work was supported in part by the national natural science foundation of china ( grants no.11075150 , no.11005101 ) , and the specialized research fund for the doctoral program of higher education ( grant no.20093402110030 ) . nima arkani - hamed , savas dimopoulos , gia dvali , phys . lett . * b429 * , 263(1998 ) , arxiv : hep - ph/9803315 ; phys . rev . * d59 * , 086004(1999 ) , arxiv : hep - ph/9807344 . i. antoniadis , n. arkani - hamed , s. dimopoulos , g. dvali , phys . lett . * b436 * , 257(1998 ) , arxiv : hep - ph/9804398 . n. agarwal , v. ravindran , v.k . tiwari , a. tripathi , nucl . b830 * , 248(2010 ) , arxiv:0909.2651 ; phys . rev . * d82 * , 036001(2010 ) , arxiv:1003.5450 . kumar , p. mathews , v. ravindran , a. tripathi , phys . * b672 * 45(2009 ) , arxiv:0811.1670 . s. ask , eur . j. * c60 * , 509(2009 ) , arxiv:0809.4750 . xiangdong gao , et al . , phys . rev . * d81 * , 036008(2010 ) , arxiv:0912.0199 . kumar , p. mathews , v. ravindran , s. seth , nucl . b847 * , 54(2011 ) , arxiv:1011.6199 . a. lazopoulos , k. melnikov , f. petriello , phys . rev . * d76 * , 014001(2007 ) , arxiv : hep - ph/0703273 . v. hankele , d. zeppenfeld , phys . lett . * b661 * , 103(2008 ) , arxiv:0712.3544 . g. bozzi , et al . , phys . rev . * d81 * , 094030(2010 ) , arxiv:0911.0438 . aleph and delphi and l3 and opal and lep electroweak working group collaborations , cern - ph - ep/2005 - 051 , arxiv : hep - ex/0511027 . measurement of the w+w - gamma cross section and direct limits on anomalous quartic gauge boson couplings at lep l3 collaboration , phys . b490 * , 187(2000 ) , arxiv : hep - ex/0008022 .

we investigate the effect induced by the kaluza - klein ( kk ) graviton in the @xmath0 production in the framework of the large extra dimensions ( led ) model at both the cern large hadron collider ( lhc ) and the international linear collider ( ilc ) . the integrated cross sections and various kinematic distributions in the led model are presented and compared with those in the standard model . the results show that the contributions from kk - graviton exchange remarkably affect the observables of the triple gauge boson ( @xmath0 ) production processes at both the ilc and lhc , particularly either in the high transverse momentum region or in the central rapidity region . we also find that the relative led discrepancy for the @xmath0 production at the lhc is generally larger than that at the ilc due to the additional led contribution via @xmath1 fusion subprocess and the kk - graviton exchanging resonant effect induced by the continuous large colliding energy in @xmath2 collision . we conclude that the @xmath3 and @xmath4 productions at the lhc could have the distinct advantage over at the ilc from the aspect of effectively exploring the led signal in measuring @xmath0 production . = 0.32 in addtoresetequationsection

it is seen that a large population of the healthy adult population has low or borderline low serum 25(oh)d levels which further increases the risk of falls and fracture . optimization of vitamin d status is therefore an essential component of preventing and managing osteoporosis especially in vulnerable groups like postmenopausal women . definition of optimum levels of vitamin d for maintenance of bone health has been a matter of debate . however , the evolving consensus is to define vitamin d deficiency ( vdd ) as a serum 25(oh)d level of less than 20 ng / l ( 50 nmol / l ) and insufficiency as a level of 25(oh)d of 21 - 29 ng / ml ( 525 to 725 nmol / l ) . vitamin d intoxication is observed when serum levels of 25(oh)d are greater than 150 ng / ml ( 374 nmol / l ) . vitamin d synthesis is affected by geographical location ( latitude and altitude ) , atmospheric pollution , clothing , melanin pigmentation , and sunlight exposure . vitamin d deficiency is rampant . in india , it has been reported from all over the country ( both rural and urban ) , in all age groups including toddlers , school children , adolescent girls , pregnant women , and postmenopausal women . the indian council of medical research ( icmr ) recommends daily intake of 600 mg of calcium in adults and 800 mg of calcium in postmenopausal age group . the typical indian diet is deficient in calcium , which becomes more important in postmenopausal women where calcium requirement is more . the icmr recommended daily allowance data states that habitual indian diet does not provide even 10% daily vitamin d requirement and sunlight is the main source of vitamin d. it continues to recommend 400 iu / day of oral vitamin d regardless of the special requirement . considering these facts , in typical indian clinical practice it is standard to recommend calcium tablets , each containing 500 mg of calcium and 250 iu of vitamin d3 , twice daily as supplementation in the postmenopausal women . the current study was planned to see the effect of two different daily doses ( 500 iu the standard and 1000 iu ) of vitamin d supplementation added to standard calcium dose ( 1000 mg / day ) , on vitamin d levels and parameters of calcium homeostasis ( calcium , phosphorus , and alp ) in postmenopausal women . we hypothesized that 1000 iu vitamin d was superior in comparison to 500 iu , which is the commonly used daily dose , for achieving serum 25(oh)d level > 20 ng / ml . the study was conducted at a tertiary care hospital at new delhi , india , after ethical clearance from the institutional review board . post - menopausal women volunteers ( mainly attendants of patients who presented in the out - patient department or medical and paramedical staff and their relatives , representing a relatively high socioeconomic strata relative to the national average ) who were not taking calcium or vitamin d supplementation for minimum 3 months and were permanent residents of the city for past 3 months were enrolled . at induction , subjects on calcium or vitamin d replacement or any drugs affecting vitamin d status , chronic renal failure , chronic liver disease , chronic smokers , and chronic alcoholics were excluded . a total 92 subjects were enrolled from the months of september to november . at induction , morning fasting samples were collected for serum calcium , phosphorus , alkaline phosphatase , albumin , and 25(oh)d after written informed consent . the group a ( n = 30 ) served as control and received only 1000 mg calcium carbonate daily in equally divided two doses , group b ( n = 31 ) received 1000 mg of calcium carbonate and 500 iu of vitamin d ( as a combination tablet containing 500 mg calcium carbonate and 250 iu vitamin d ) daily in equally divided two doses , and group c ( n = 31 ) received 1000 mg of calcium carbonate and 1000 iu of vitamin d ( as a combination tablet containing 500 mg calcium carbonate and 500 iu vitamin d ) daily in equally divided two doses . the tablets were procured from eris pharmaceuticals which were market preparations decal ( a combination tablet containing 500 mg calcium carbonate and 250 iu vitamin d ) , d-500 cal ( a combination tablet containing 500 mg calcium carbonate and 500 iu vitamin d ) , while plain calcium tablets containing 500 mg calcium carbonate were manufactured for the study after appropriate approval . compliance was considered as consumption of at least 80% of the supplied tablets . at the end of three months morning fasting samples were collected for measurement of serum calcium , phosphorus , alkaline phosphatase , albumin , and serum 25(oh)d levels in subjects who were considered to be compliant . serum albumin , calcium , phosphorus , and alkaline phosphatase estimation was performed on the auto - analyzer immediately . serum 25(oh)d concentrations were estimated by radioimmunoassay after storage at 20c ( diasorin , stillwater , mn 55082 - 0285 , usa ; kit , normal range : 9.3 - 37.9 ng / ml ) . the sensitivity of this assay was 1.5 ng / ml , within - run coefficient of variation ( cv ) was 10.5% , and the total imprecision cv was 8.2% at 22.7 ng / ml . primary outcome was the change in the mean serum 25(oh)d level from baseline in the group receiving 1000 iu of vitamin d per day as compared to the group receiving 500 u of vitamin d per day and the group not receiving any vitamin d supplementation , at the end of three months of intervention . secondary outcome was the change in mean serum calcium ( corrected for serum albumin ) , phosphorus , and alkaline phosphatase level from baseline in the three groups at the end of 3 months of intervention . the data are presented in mean sd , and non - parametric test , kruskal wallis test , was used to assess the significance level of the percentage change in serum 25(oh)d , corrected calcium , phosphorus , and alkaline phosphatase within and between the groups . the data are presented in mean sd , and non - parametric test , kruskal wallis test , was used to assess the significance level of the percentage change in serum 25(oh)d , corrected calcium , phosphorus , and alkaline phosphatase within and between the groups . a total of 92 postmenopausal women were enrolled from the months of september to november and followed up for 3 months from the date of enrolment . the mean age of the subjects in the study population was 54.8 6.7 years ( range 40 - 73 ) . their mean daily calcium intake was 1076.43 376.2 mg and median of daily sun exposure was 5 ( range 0 - 38 ) min with exposure of about 20% body surface area . the mean daily calcium intake was relatively higher than the national average probably due to a higher socioeconomic status of the subjects included . 83.7% subjects ( n = 77 ) had vitamin d deficiency ( 25(oh)d < 20 ng / ml ) and 8.7% ( n = 8) subjects had vitamin d insufficiency ( 25(oh)d 20 - 30 ng / ml ) and 7.6% subjects ( n = 7 ) had normal vitamin d defined as 25(oh)d > 30 ng / ml [ table 1 ] . baseline parameters ( meansd ) in three groups thirty ( 30 ) subjects were randomized to group a , while 31 subjects each were randomized to groups b and c. the baseline parameters were not significantly different in the three groups as assessed by the kruskal wallis test to evaluate the significance [ table 2 ] . studied parameters at three months follow up ( meansd ) at the end of follow up , 26 from group a , 29 from group b , and 23 from group c presented for second sampling . four subjects from group a , two from group b , and six from group c withdrew consent during the course of the study and two subjects from group c were lost to follow up . data for subjects with less than 80% compliance ( five subjects from group a and c each and four from group b ) were excluded . data for 21 ( 70% ) , 25 ( 80.6% ) , and 18 ( 58.06% ) subjects from groups a , b , and c , respectively , were finally analyzed [ figure 1 ] . at 3 months , the difference in percentage change in mean serum 25(oh)d level from baseline in between the three groups was statistically significant ( p < 0.05 ) with percentage change being maximum in group c ( 178.78% ) and group a actually showing a decline [ table 3 ] . figure 2 shows the comparison in mean serum 25(oh)d level at baseline and at 3 months in between the three groups . percentage change in various parameters at 3 months from baseline ( meansd ) mean levels of 25(oh)d at baseline and 3 months in the three groups although not significantly different ( p > 0.05 ) , the mean serum calcium attained in group c was highest ( 8.67 mg / dl ) from the average baseline corrected calcium of 8.49 mg / dl . the mean serum phosphorus and alkaline phosphatase in the three groups were not significantly different within or between the groups at the end of follow up [ table 2 ] . twelve subjects ( four in group a , three in group b , and five in group c ) reported minor gastritis and abdominal discomfort but did not result in discontinuation of the supplementation . this study evaluates the response of different doses ( 500 iu daily , 1000 iu daily or control ) of vitamin d along with 1000 mg of calcium daily on the parameters of calcium homeostasis in healthy postmenopausal women . it was carried out in new delhi ( location 28.38n , 77.12e ) . this city experiences marked seasonal variation . subjects were recruited from september to november , prior to the onset of peak winter . since the subjects were randomly divided into the three groups , any effect of season was equally distributed . in the present study , 83.7% subjects ( n = 77 ) had vitamin d deficiency ( 25(oh)d < 20 ng / ml ) , 8.7% ( n = 8) subjects had vitamin d insufficiency ( 25(oh)d 20 - 30 ng / ml ) , and 7.6% subjects ( n = 7 ) had normal vitamin d defined as 25(oh)d > 30 ng / ml . our results are in accordance with other studies which have demonstrated high prevalence of vitamin d deficiency in india although limited data is available regarding postmenopausal women . from a study conducted in delhi , the authors reported vdd in 91.2% among older indian adults ( more than 50 years age ) of both sexes despite the fact that more than half the subjects studied were taking 200 - 400 iu of oral vitamin d daily . in a study from the southern part of the country , vitamin d deficiency ( < 20 ng / ml ) , insufficiency ( 20 - 30 ng / ml ) and replete states ( > 30 ng / ml ) were seen in 70% , 23% , and 7% , respectively , among postmenopausal women , similar to levels in reproductive age women . similarly , in another study conducted among postmenopausal south indian women ( n = 164 ) , the author found that only 18% patients had normal 25(oh)d levels ( > 20 ng / ml ) , 52% had 25(oh)d insufficiency ( 10 - 20 ng / ml ) , and 30% had 25(oh)d deficiency ( < 10 ng / ml ) . data from other study populations suggests the universal presence of low vitamin d levels even though variable cut - offs were used . in the study conducted in delhi , at the same institute where the present study was conducted , among 100 healthy volunteers from the hospital staff , the mean 25(oh)d was 4.7 3.4 ng / ml . all the subjects had hypovitaminosis d ( < 20 ng / ml ) and more than 90% subjects had 25(oh)d levels < 10 ng / ml . in a study conducted among healthy hospital staff , in lucknow , a city south east of delhi , the authors found 66.3% of their subjects to be vitamin d deficient , using a cut - off value of 15 ng / ml . of these , 20.6% had severe vitamin d deficiency ( < 5 ng / ml ) , 27.2% had moderate ( 5 - 9.9 ng / ml ) , while 18.5% had mild vitamin d deficiency ( 10 - 14.9 ng / ml ) . when a serum 25(oh)d level of 20 ng / ml was used as a cut - off value similar data has been reported from other parts of the country . in a study among healthy adult native population , from kashmir , 83% of the subjects studied had vitamin d deficiency ( serum 25(oh)d concentration of < 50 nmol / l equivalent to 20 ng / ml ) . 25% , 33% , and 25% had mild ( 25 - 50 nmol / l equivalent to 10 - 20 ng / ml ) , moderate ( 12.5 - 25 nmol / l equivalent to 5 - 10 ng / ml ) , and severe ( < 12.5 nmol / l equivalent to 5 ng / ml ) deficiency , respectively . the prevalence of vdd ranged from 69.6% in the employed group to 100% in the household group with equal prevalence of vdd in subjects from rural and urban areas . similarly , high prevalence of vitamin d deficiency was reported among pregnant women and adolescent girls from a rural indian community . boys were found to be relatively protected . the age - adjusted community prevalence of vitamin d deficiency , defined as 25(oh)d < 50 a significant urban and rural difference is seen in the serum level of 25(oh)d but despite long hours of sun exposure , the rural population is also deficient . in a study conducted among residents of a north indian village with 200 families , males had significantly higher 25(oh)d values than females . when compared to urban subjects , the mean serum 25(oh)d value of rural males and females was six- and threefolds higher , respectively . however , even with 5 hours of daily sunshine exposure only 31.5% had serum 25(oh)d levels 50 nmol / l ( 20 ng / ml ) . in a study conducted among urban and rural population in andhra pradesh , they found that the 25(oh)d levels of rural adult subjects were significantly higher ( p < 0.001 ) than that of urban adult subjects in both males and female groups . the icmr recommends daily intake of 600 mg of calcium in adults and 800 mg of calcium in postmenopausal age group . the typical indian diet is deficient in calcium , which becomes more important in postmenopausal women where calcium requirement is more . the icmr recommended daily allowance data states that habitual indian diet does not provide even 10% daily vitamin d requirement and sunlight is the main source of vitamin d. it continues to recommend 400 iu per day of oral vitamin d regardless of the special requirement like in postmenopausal women . the iof recommends that vitamin d intake may need to be adjusted upward to as much as 2000 iu / day in individuals who are obese , and in those with osteoporosis , limited sun exposure ( institutionalized , homebound ) , and malabsorption , and in non - european populations known to be at high risk for vitamin d deficiency such as those in the middle east and south asia , or immigrants from such regions living in europe . at the end of follow up , the mean 25(oh)d level was highest in group c at 23.71 ng / ml . in group a it was 8.07 ng / ml , in group b it was 13.34 ng / ml , while at baseline the average 25(oh)d level was 13.43 ng / ml . the percentage change in mean serum 25(oh)d level from baseline was significantly different in between the three groups ( p = 0.000 ) with percentage change being maximum in group c ( 178.78% ) and group a actually showing a decline . the decline probably reflects the effect of season as the follow - up period was winters . whatever the effect of season , it was presumed that it would be uniform in the three groups . our results suggest that 1000 iu vitamin d is better as compared to the currently prescribed doses of 500 iu daily . however , even this dose is not sufficient to optimize the levels in a severely deficient population . the number of subjects who attained serum 25(oh)d level 30 ng / ml was four ( 22.2% ) in group c , one ( 4% ) in group b , and none in the control group . the percentage of subjects who attained serum 25(oh)d level of 20 - 30 ng / ml in the three groups was 38.9% ( n = 7 ) , 12% ( n = 3 ) , and 4.7% ( n = 1 ) , respectively . there percentage change in the blood levels of corrected serum calcium , phosphorus and total alkaline phosphatase from baseline was not different between the three groups . our results are in line with the results of previous studies . in a study conducted among older adults , it was seen that there was no difference in the prevalence of vitamin d deficiency among subjects who were and those who were not receiving vitamin d supplementation in dose ranging from 200 to 400 iu / day . in a previously conducted study from delhi in healthy adults , the authors concluded that monthly oral administration of 60,000 iu cholecalciferol ( ~2000 iu / day or 50 g / day ) is effective in raising serum 25(oh)d to desired levels ( > 30 ng / ml ) during summer . however , higher doses of cholecalciferol120,000 iu / month administered orally ( ~4000 iu / day or 100 g / day)may be more appropriate during winter . from their study among ambulatory elderly in finland , the authors concluded that 10 g / d ( 400 iu ) is not enough to maintain 25(oh)d above 40 an optimal daily dose of 115 g / d ( 4600 iu ) was predicted statistically , to obtain 25(oh)d levels within the range of 75 - 220 our study suggests that even 1000 iu daily for 3 months may not be enough to attain optimum levels of serum 25(oh)d ; and probably a higher dose is required to attain optimum levels . in our study , the mean 25(oh)d level in group c after 3 months of supplementation was less than 30 ng / ml ( 23.71 ng / ml ) suggesting that even 1000 iu may not be sufficient to attain normal levels of 25(oh)d and a higher dose as much as 2000 iu / day may be required in special populations as postmenopausal women especially in the indian subcontinent . as previously seen , the effects of calcium and vitamin d are not sustained and levels decline after some time . the subjects included in the study were based on convenience sampling and not population based sampling . our study was a non - blinded and the subjects knew the nature of supplementation they were receiving . it sometimes could have affected compliance as the subjects were given the background information related to the study . the number of subjects for final analysis after excluding the dropouts and subjects with less than 80% compliance was relatively small . standard dose of vitamin d available in calcium tablets ( 250 iu per 500 mg calcium carbonate ) is not adequate for achieving optimum serum 25(oh)d levels . higher dose of vitamin d supplementation with 1000 iu / day ( 500 iu per 500 mg calcium carbonate ) daily was superior to the standard dose therapy and resulted in serum 25(oh)d values > 20 ng / ml in postmenopausal women in our study . for achievement of optimum serum 25(oh)d levels ( > 30 ng / ml ) , it is possible that the standard recommended dose may be adequate for maintenance in a however , in the indian population which is severely deficient , even 1000 iu daily cholecalciferol supplementation is not adequate . at this point therefore , it is recommended to make the population sufficient by giving therapeutic doses of vitamin d to the diagnosed cases . further studies are required to evaluate higher doses in indian postmenopausal women which will achieve and maintain optimal vitamin d levels without risk of toxicity .

aim : to compare the effect of two different doses ( 500 and 1000 iu / day ) of oral vitamin d3 ( cholecalciferol ) on serum 25-hydroxy vitamin d [ 25(oh)d ] levels in apparently healthy postmenopausal indian women.materials and methods : serum 25(oh)d , calcium with albumin , phosphorus , and alkaline phosphatase were measured in 92 apparently healthy postmenopausal women . the subjects were randomly assigned to one of the three groups and received supplementation for 3 months each . each group received 1000 mg calcium carbonate daily while groups b and c received 500 and 1000 iu of cholecalciferol in addition , respectively . the tests were repeated after 3 months.results:at baseline , 83.7% subjects had vitamin d deficiency ( 20 ng / ml ) . the difference in the percentage change in mean serum 25(oh)d levels from baseline in group a ( 30.5 5.3% ) , group b ( + 8.9 19.7% ) , and in group c ( + 97.8 53.3% ) was statistically significant ( p < 0.001 ) between the three groups . serum 25(oh)d level > 20 ng / ml was achieved in 4.7% ( 1/21 ) , 16% ( 4/25 ) , and 66.67% ( 12/18 ) subjects in groups a , b , and c , respectively . no significant change was found in serum calcium , phosphorus , and alkaline phosphatase levels at 3 months in either of the groups from baseline.conclusions:standard dose of cholecalciferol available in calcium tablets ( 250 iu per 500 mg calcium carbonate ) is not adequate for achieving optimum serum 25(oh)d levels in indian postmenopausal women . higher dose of vitamin d supplementation with 1000 iu / day ( 500 iu per 500 mg calcium carbonate ) daily is superior to the standard dose therapy . for achievement of optimum serum 25(oh)d levels ( > 30 ng / ml ) in indian postmenopausal women , still higher doses of vitamin d are likely to be required .

SECTION 1. SHORT TITLE, FINDINGS. (a) Short Title.--This Act may be cited as ``Fire Safe Cigarette Act of 1994''. (b) Findings.--The Congress finds that-- (1) cigarette ignited fires are the leading cause of fire deaths in the United States, (2) in 1990 there were 1,200 deaths from cigarette ignited fires, 3,360 civilian injuries from such fires, and $400 million in property damage caused by such fires, (3) over 100 children are killed each year from cigarette related fires, (4) the results accomplished under the Cigarette Safety Act of 1984 and the Fire Safe Cigarette Act of 1990 complete the necessary technical work for a cigarette fire safety standard, (5) it is appropriate for the Congress to require by law the establishment of a cigarette fire safety standard for the manufacture and importation of cigarettes, (6) the most recent study by the Consumer Product Safety Commission found that the cost of the loss of human life and personal property from not having a cigarette fire safety standard is $4,000,000,000 a year, and (7) it is appropriate that the regulatory expertise of the Consumer Product Safety Commission be used to implement a cigarette fire safety standard. SEC. 2. CIGARETTE FIRE SAFETY STANDARD. (a) In General.--Not later than one year after the date of the enactment of this Act, the Consumer Product Safety Commission shall by rule issue a cigarette fire safety standard for cigarettes to reduce the risk of ignition presented by cigarettes. In establishing the standard the Commission shall-- (1) consult with the National Institute of Standards and Technology and make use of its capabilities as it deems necessary and seek the advice and expertise of other Federal and State agencies engaged in fire safety, and (2) take into account the final report to the Congress made by the Commission and the Technical Advisory Group established under section 3 of the Fire Safe Cigarette Act of 1990 in which it was found that cigarettes with a low ignition propensity are already on the market. (b) Stockpiling.--The Commission shall include in the rule issued under subsection (a) a prohibition of stockpiling of cigarettes to which the standard issued under subsection (a) will not apply. For purposes of this subsection, the term ``stockpile'' means the manufacturing or importing of a cigarette between the date a standard is issued under subsection (a) and the date the standard is to take effect at a rate greater than the rate the cigarettes were manufactured or imported for the one year period ending on the date the standard was issued. (c) Procedure.--The rule under subsection (a) shall be issued in accordance with section 553 of title 5, United States Code. (d) Effective Date.--The Commission shall prescribe the effective date of the rule issued under subsection (a), except that such date may not be later than 2 years after the date of the enactment of this Act. (e) Judicial Review.-- (1) General rule.--Any person who is adversely affected by a rule issued under subsection (a) may, at any time before the 60th day after the Commission issues the rule, file a petition with the United States Court of Appeals for the District of Columbia Circuit or for any other circuit in which such person resides or has its principal place of business to obtain judicial review of the rule. A copy of the petition shall be forthwith transmitted by the clerk of the court to the Secretary. The Commission shall file in the court the record of the proceedings on which the Commission based the rule as provided in section 2112 of title 28, United States Code. (2) Additional evidence.--If the petitioner applies to the court for leave to adduce additional evidence, and shows to the satisfaction of the court that such additional evidence is material and that there was no opportunity to adduce such evidence in the proceeding before the Commission, the court may order such additional evidence (and evidence in rebuttal thereof) to be taken before the Commission in a hearing or in such other manner, and upon such terms and conditions, as the court deems proper. The Commission may modify the Commission's findings as to the facts, or make new findings, by reason of the additional evidence so taken, and the Commission shall file such modified or new findings, and the Commission's recommendations, if any, for the modification of the rule. (3) Court jurisdiction.--Upon the filing of a petition under paragraph (1), the court shall have jurisdiction to review the rule of the Commission, as modified, in accordance with chapter 7 of title 5, United States Code. SEC. 3. ENFORCEMENT. (a) Prohibition.--No person may manufacture or import a cigarette unless the cigarette is in compliance with a cigarette fire safety standard issued under section 2(a). (b) Penalty.--A violation of subsection (a) shall be considered a violation of section 19 of the Consumer Product Safety Act. SEC. 4. PREEMPTION. (a) In General.--This Act and the cigarette fire safety standard promulgated under section 2(a) do not preempt or otherwise affect in any way any law of a State or political subdivision which prescribes a fire safety standard for cigarettes which is more stringent than the standard promulgated under section 2(a). (b) Defenses.--In any civil action for damages compliance with the fire safety standard promulgated under section 2(a) may not be admitted as a defense. SEC. 5. DEFINITIONS. For purposes of this Act: (1) The term ``Commission'' means the Consumer Product Safety Commission. (2) The term ``cigarette'' has the meaning prescribed by section 3 of the Federal Cigarette Labeling and Advertising Act.

Fire Safe Cigarette Act of 1994 - Directs the Consumer Product Safety Commission to issue by rule a fire safety standard for cigarettes. Prohibits stockpiling of cigarettes between the issuing and effective dates of the standard. Provides for judicial review of the standard. Prohibits manufacture or importing of cigarettes unless in compliance with such standard. States that this Act and the standard issued under it does not preempt any law of a State which prescribes a more stringent fire safety standard for cigarettes.

FILE PHOTO: Actor Robin Williams poses as he arrives at the British Academy of Film and Television Arts Los Angeles Britannia Awards in Beverly Hills, California November 30, 2011. REUTERS/Fred Prouser LOS ANGELES (Reuters) - Suicide rates in the United States spiked almost 10 percent following the death in 2014 of actor Robin Williams, and spiked even more among men and those who ended their lives, like Williams, by suffocation, according to a study published on Wednesday. The study, published in the scientific journal PLOS One, found that in the five months from August to December 2014 some 18,690 deaths by suicide were recorded - an increase of 9.85 percent from the expected number of cases for the period. Williams, the Oscar-winning star of “Good Morning, Vietnam” who was beloved for his humor, died in August 2014 at age 63 in a suicide that shocked fans worldwide. Authorities said he died of asphyxia after hanging himself at his home in northern California. An autopsy found that Williams was suffering from Lew body dementia, which causes a progressive decline in mental ability. Suicides following Williams’ death rose by 12.9 percent in men aged 30-44, and the study found a 32 percent increase in the number of deaths from suffocation. Although the study could not prove a definitive link, it said there appeared to be a connection. Extensive media coverage of Williams’ death “might have proved the necessary stimulus for high-risk segments of the U.S. population (e.g. middle-aged men in despair) to move from suicidal ideation to attempt.” While the effects of widely reported celebrity suicides have previously been linked to increases in the wider population, the study said media coverage of Williams’ suicide was particularly detailed and sensational and was amplified through social media. The suicide in 1994 of Nirvana lead singer Kurt Cobain, for example, appeared to have a minimal impact on suicide rates in his Seattle home town, partly because of more restricted reporting, the study said. “The media industry can positively or negatively influence imitation suicides,” the study said. “Popular news media headlines suggest that media guidelines for suicide reporting were not followed in the case of Mr. Williams.” The study used data collected by the Centers for Disease Control and Prevention. ||||| Investigating suicides following the death of Robin Williams, a beloved actor and comedian, on August 11 th , 2014, we used time-series analysis to estimate the expected number of suicides during the months following Williams’ death. Monthly suicide count data in the US (1999–2015) were from the Centers for Disease Control and Prevention Wide-ranging ONline Data for Epidemiologic Research (CDC WONDER). Expected suicides were calculated using a seasonal autoregressive integrated moving averages model to account for both the seasonal patterns and autoregression. Time-series models indicated that we would expect 16,849 suicides from August to December 2014; however, we observed 18,690 suicides in that period, suggesting an excess of 1,841 cases (9.85% increase). Although excess suicides were observed across gender and age groups, males and persons aged 30–44 had the greatest increase in excess suicide events. This study documents associations between Robin Williams’ death and suicide deaths in the population thereafter. Celebrity suicide effects have led to the World Health Organization to establishment media guidelines for reporting a high profile celebrity death, including sensitivity and non-sensationalism in the reporting of the means of suicide, the precipitating factors, and the risk factors for suicide apparent in the deceased [ 14 ], and clear and consistent messages about suicide prevention and help-seeking during reporting [ 6 , 15 ]. The extent to which these guidelines were followed after the death of Mr. Williams, however, is questionable, and as such, we examined suicide incidence in the United States by month surrounding the time frame of Mr. Williams’ death. The effects of a widely reported celebrity suicide on population health are extensively documented in the international literature [ 1 – 9 ]. Recent meta-analysis suggests that, on average, suicides increase by approximately 0.26 per 100,000 population in the weeks following a high profile celebrity suicide [ 1 ], with heterogeneity in the magnitude of the effect across country, event, and celebrity. Effects are particularly prominent when the celebrity is an entertainment star [ 2 , 3 ], among other factors. While some evidence indicates that suicides in the population tend to increase among those at a similar age as the deceased and using a similar method [ 4 , 10 , 11 ], such evidence is not always consistent [ 12 ]. However, there is a paucity of evidence about the effects of a celebrity suicide on population health within the U.S. [ 13 ], and no study, to our knowledge, has examined this effect within the modern era of the 24-hours news cycle. On August 11, 2014, well-known actor and comedian Robin Williams committed suicide in his home in Paradise Cay, California at the age of 63. The details of his suicide were widely reported in the media in the days and weeks that followed. Although Williams’ widow revealed his struggles with Lewy Body Dementia, the initial reports on Williams’ death did not mention this condition. Time-series analysis was used to determine the expected number of suicides during the months following Williams’ death. Over the calendar year, the monthly number of suicides in a population tends to exhibit a seasonal pattern, with a peak in the early spring and trough in the summer months. As a result, the error term of these observations are often autocorrelated, and not independent, which violates an assumption of ordinary least squares regression. Time-series analysis accounts for the violations of the independence assumption and models the data generating process. Therefore, we used a seasonal autoregressive integrated moving averages (SARIMA) model for this study [ 17 ]. Seasonal variation and linear trends were removed by differencing the population parameters between successive years and months, respectively. We examined both the autocorrelation function and partial autocorrelation function to identify the best fitting autoregressive and moving average parameters. The model that provided the lowest Akaike information criterion and Bayesian information Criterion was chosen to best model the data generation process. To assess the difference in observed suicides and expected suicides following Williams’ death on August 14 th , 2014, we used an SARIMA(0,1,1)x(0,1,1)12 to model the observed number of suicides from January 1999 to July 2014 and forecasted the expected number of suicides, and 95% confidence intervals (CIs), from August 2014 to December 2014. There was no evidence that residuals deviated from white noise (Q tests, p = 0.31). All analyses were performed using R version 3.2.4 (Vienna, Austria) and STATA version 14 (College Station, Texas). We also used the Bloomberg Terminal’s ( http://www.bloomberg.com/professional/education/ ) news trend (NT) function to identify the number of global English-language news media reports with first, the terms Suicide and Dead, and second, the term Robin Williams. To provide a comparison to the same time during the previous year, we analyzed the number of news media reports from June 1, 2013 to January 1, 2015. As a sensitivity test, we used the same method to forecast the five months interval from August to December in 2013, one year prior to Williams’ suicide ( Fig 4 ). Using the same method that we employed to predict the number of monthly suicides following Williams’ death, we found the model performed very well (i.e., the predicted counts overlapped the observed counts), suggesting that any differences between the observed and predicted number of suicides in the months that followed Williams’ death were likely not attributed to modelling decisions. Increases in suicides from August to December 2014 were consistently observed across gender, both in males (9.1%) and females (9.7%), and across all age groups; those ages 30–44 showed the greatest increase in suicides (12.9%) ( Table 1 ). These increments represent and excess of 1,841 cases (1,398 among males, 386 among females, and 175, 265, 577, 363 and 376 cases among those 12–19, 20–29, 30–44, 45–59 and 60+, respectively). Finally, Table 2 show that, compared to all other methods of suicide, the difference between the observed and predicted number of suicides was greatest and most consistent among suffocation suicides. Specifically, we observed a 32.3% increase in the number of suffocation suicides in the five months that followed Williams’ death, compared to a 3.1% increase in the number of suicides from all other methods combined (i.e., cutting/piercing, poisoning, firearm, falls, all other methods), albeit we found a higher than expected number of poisoning suicides and firearm suicides in August and September, respectively. Fig 2 shows the number of suicides in the United States by month from 2010 through 2015. Monthly suicide counts followed a consistent seasonal pattern over the year, with the fewest suicides occurring in February and counts increasing over the summer months. Furthermore, monthly suicide counts tended to increase each year over the prior year’s count for that same month such that more suicides were recorded for January 2011 than January 2010. Compared to prior years, there was a marked increase in the number of suicides beginning in August 2014 through December 2014. This increase in the number of suicides per month appeared to remain consistent over 2015. News media reports with the terms Suicide and Dead, and the term Robin Williams drastically increased in the weeks after Mr. Williams’ death ( Fig 1 ). These increments in media reports were greater that those observed in previous months and also during the August-December period in 2013. Although the maximum number of stories about Robin Williams was during the approximately four weeks after his death from August-September 2014, stories about Williams were published during the entire period from August-December 2014. Discussion There was an excess of approximately 1,841 suicides in the United States in the four months after the death of Robin Williams compared to what would be expected for that time period based on forecasted models. While excess suicides were observed across all gender and age groups, the highest excesses were observed for men (1,398 excess suicides) and persons 30–44 years (577 excess suicides). Furthermore, the difference between the observed and expected number of suicides were a function of a greater than expected number of suffocation suicides, over all other methods. Although we cannot determine with certainty that these deaths are attributable to the death of Robin Williams, we found both a rapid increase in suicides in August 2014, and specifically suffocation suicides, that paralleled the time and method of Williams’ death, and a dramatic increase in news media reports on suicides and Robin Williams during this same period, suggesting a connection between Williams’ death and the subsequent increase in suicide deaths from August to December 2014. Our findings extend previous studies that have documented a parallel increase in media reporting of suicides and suicide rates [1, 6, 15, 18, 19]. Our study used a SARIMA model to estimate the predicted number of suicides in the months that followed Williams’ death. This method represents a substantial improvement over previous methods employed in this literature. For example, Phillips [20], in an attempt to estimate the number of suicides expected in a given month, averaged the number of suicides that occurred in that month during the year prior to and after the event. Whereas our sensitivity analysis demonstrated accurate prediction of suicides from August to December in 2013, one year prior to Williams’ suicide, Phillips [20] averaging method overestimated the predicted number of suicides in August 2014, predicting 3746 suicide deaths in August 2014 (3580 deaths in August 2013 plus 3912 deaths in August 2015 divided by 2), compared to our SARIMA model, predicting 3585.72 (95% CI: 3399.25, 3782.42). Increased access to fast, low-cost, computing over the past several decades has led to more recent literature using SARIMA models to predict suicide deaths in a given month, over Philips averaging method. Our findings that document a parallel increase in media reporting of suicides and suicide rates suggest that media reporting possibly inducing changes in suicidal ideation via reinforcement, as social learning theory suggests [21, 22]. In this regard, Kumar et al. (2015) described how Williams’ death was also followed by an increased number of online posts in the “SuicideWatch” forum (a suicide support platform in Reddit), and also with changes in posted content linked to suicidal ideation (e.g. expressing greater negativity, anxiety and anger, and manifesting decreased social concerns) [23]. Further, it is hypothesized that celebrity suicides may influence the population patterns of suicide given the ubiquity of knowledge about the celebrity, and potential identification with the celebrity as a model for a subsequent suicide. Identification with the deceased as a mechanism for so-called “copycat suicides” has long been described as a “Werther effect” [20, 24], named after a 1774 novel by Johann Wolfgang von Goethe. That we observed the greatest excess suicide cases were among persons who used a similar method (i.e., suffocation) and who were of the same sex (i.e., male) and in a similar age group as Williams, it is possible that this excess in suicide cases is an example of the “Werther effect”. The link between media and suicides is also supported by the fact that interventions aiming at guiding media reporting have an impact on suicides following specific suicide cases [1, 15, 25, 26]. Popular news media headlines suggest that media guidelines for suicide reporting were not followed in the case of Mr. Williams. For example, media guidelines suggest that explicit description of the suicide method be avoided, as well as speculation on causes or details of site of suicide, especially in headlines [14]; however, on August 12th, 2014, the Washington Post reported “Robin Williams’s death shows the power of depression and the impulsiveness of suicide” [27] and the New York Times reported with the headline “Robin Williams Died by Hanging, Official Says” [28]. Similar headlines can be found across many other population news media sources. A public news conference by the Sheriff assigned to the case detailed the belt that was used in Williams’ death, his body position, and wrist marks, among other details. Thus, substantial evidence suggests that the major US news media outlets tended to deviate from the established suicide reporting guidelines following Williams’ death. Oversights in media reporting regarding the death of Robin Williams stands in contrast to another high profile US entertainment star suicide, Kurt Cobain, lead singer of the enormously popular rock band Nirvana, in 1994. There was minimal impact of Cobain’s death on suicide rates in the Seattle area of the United States, and available evidence indicates that restrictive reporting of the details of death, as well as consistent messages regarding suicide prevention throughout reporting, may have played a pivotal role in preventing subsequent suicides [29, 30]. It should be noted that this study only counted suicides before and after Cobain’s death in the Seattle area (29), and it is possible that the suicide trends in Seattle differed from the national trends. It is also worth considering the role of social media as a new and emerging risk factor for how information is disseminated after the death of a celebrity. The PEW research center estimates that as of 2015, approximately 65% of adults in the US receive their news updates through Facebook and Twitter [31]. Even if traditional media outlets follow established reporting guidelines for celebrity suicides, the role of social media speculation and news dissemination may counter any prevention messages that are disseminated in traditional sources. There are 4 limitations important for interpretation of this study. First, we cannot determine with certainty that the increase in deaths from August to December 2014 can be attributed to the death of Robin Williams. It is possible that a different event, capable of increasing population suicide rates, occurred during the same period as Williams’ death in August 2014. While we cannot entirely rule-out such an event during this time period, we find this hypothesis unlikely given that the greatest spike in suicide-related media reports occurred on the days following Williams’ death. Second, we did not model exogenous factors that could increase suicide risk in the population (e.g., unemployment, weather patterns). However, the SARIMA model used data from 204 time points to model the mechanism generating the monthly suicide deaths in the U.S., without the need for input from exogenous factors. However, correct specification of a SARIMA model can produce accurate predictions without the need for modeling exogenous factors. To verify our model specification, we used a sensitivity analysis to accurately predict suicide counts during the same time period (August to December) in 2013 (i.e., the year prior to Williams’ death), providing evidence accurate model specification without a need to consider exogenous factors. Third, the length of time that media reports influence copycat suicides is unknown. While we modeled a 4 month copycat effect following Williams’ suicide, many previous studies have assumed that the impact of media reporting on copycat suicides lasts approximately 4 weeks after the event [4, 9–11]. Two factors influenced our decision to consider this length of time: (1) monthly suicide counts did not return to pre-Williams’ levels until December 2014 and (2) media reports continued for several months after Williams’ death. Finally, misclassification of suicides in the death records might have led to underestimates of the effects. Our work adds evidence about the relationship between celebrity suicide, the subsequent media coverage of the event, and subsequent suicide deaths. The number of excess deaths was greatest among men and persons 30–44 years, while suffocation deaths increased over all other suicide methods. Although we cannot determine with certainty that the excess suicides were attributable to news media reports on Williams’ death, Williams’ death might have provided the necessary stimulus for high-risk segments of the U.S. population (e.g., middle-aged men in despair) to move from suicidal ideation to attempt. Therefore, the media industry can positively or negatively influence imitation suicides. Suicide remains a central threat to public health, and high profile celebrity suicides will continue to occur; preventing such effects will require substantial resources and training, as well as creative responses to emerging media. ||||| Preventing suicide: a resource for media professionals - update 2017 Overview This resource booklet is addressed to media professionals who play a role particularly relevant to the prevention of suicide. There is evidence that media reports about suicide can enhance or weaken suicide prevention efforts. The booklet is the product of continuing collaboration between WHO and the International Association for Suicide Prevention (IASP).

– The world was shocked by the August 2014 death of Robin Williams, but "middle-aged men in despair" may have taken his suicide especially hard, Reuters notes. For a study published Wednesday in Plos One, researchers sifted through CDC data from 1999 through 2015 and found that there was a "marked increase" in the number of suicides from right after Williams' death through the end of 2014, and that the monthly number of suicides continued to rise throughout 2015 as well. There were 18,690 suicides from August 2014 to December 2014, which the scientists say was a nearly 10% increase from the expected number based on data extrapolations. Among individuals ages 30 to 44, the spike was even greater during that period—about 13%—and there was a 32% increase in suicides by suffocation, which is how Williams died (he asphyxiated after hanging himself). The study admits it can't prove Williams' death was the direct cause of any "copycat" suicides—there may have been other contributing factors or misclassifications—but it says his death, and the accompanying media coverage, "might have provided the necessary stimulus for high-risk segments of the U.S. population … to move from suicidal ideation to attempt." The study notes suicides within the general population often spike after a celebrity suicide, but headlines on Williams were particularly prevalent, and social media (which wasn't a force when, say, Kurt Cobain died in 1994) may have exacerbated the exposure. The study says the effects of celebrity suicides are concerning enough that the World Health Organization has put out guidance for journalists on responsibly reporting high-profile deaths such as Williams'. (Williams' wife talks about his last 10 devastating months.)

infrared imaging has been an important observational technique for planetary nebulae ( pne ) for several reasons . first , the ejected matter from the star often obscures the inner regions of the nebula . in the infrared , one can penetrate the surrounding dust and gas and see into the regions near the central star , which may be key in understanding the formation mechanisms that lead to the pn structure . second , there are many infrared lines that are important tracers and diagnostics of shocks and photodissociation regions ( pdrs ) . these include the bright h@xmath0 line at 2.12 @xmath1 m and many other lines from 2 28 @xmath1 m , the [ fe ii ] 1.64 @xmath1 m line , and several other bright diagnostic lines such as 4.05 @xmath1 m br@xmath2 , 12.81 @xmath1 m [ ne ii ] , and other lines . finally , there are components of the nebula that can only be observed in the infrared . these include the pah emission features at 3.3 , 6.2 , 7.7 , 8.6 , and 11.2 @xmath1 m , and thermal continuum emission from hot , warm , or cool dust . since the last pne symposium , observers have made use of improved facilities and instruments to probe pne in the infrared . there are now several telescopes in the 8 - 10 m class in both hemispheres that provide a significant increase in sensitivity and resolution over what was previously available . the capability of the instruments on these telescopes has also been greatly enhanced with large - format ir imagers , many with adaptive optics ( ao ) that can deliver nearly diffraction - limited image quality at longer wavelengths . these systems utilize narrow - band filters to isolate spectral features and nearby continuum wavelengths to map the emission components of the nebula . previous and current space missions have also provided new resources for infrared imaging . surveys such as the msx survey of the galactic plane , and the all - sky 2mass survey are important datasets that are being utilized to find or study pne in the infrared . the hst / nicmos instrument has been used to study the compact structure of young pne in the near - ir . finally , the _ spitzer space telescope _ ( ( * ? ? ? * werner et al . 2004 ) ) was launched in august 2003 with three instruments that have imaging capability from 3 - 200 @xmath1 m . in this review i will summarize some representative published results since the last iau symposium , and some of the spitzer gto observations of pne . although i stress here the infrared imaging aspects of recent results , the ir emission is only one important part of the full picture of these pne . many investigators employ a multi - wavelength approach using images and spectra that greatly enhances the understanding of the pne s structure . early near - ir array camera imaging surveys ( e.g. , ( * ? ? ? * latter et al . 1995 ) ; ( * ? ? ? * kastner et al . 1996 ) ) focused on narrowband imaging of various well - studied pne , exploring the relationship between h@xmath0 emission and morphological type , and examining differences between the near - ir and optical structure . much of the recent ground - based near - ir imaging has concentrated on high angular resolution narrowband observations of young pne . the goal has been to probe the compact structures near the core and in the lobes of the pne to gain an understanding of the mechanisms that are creating the bipolar or asymmetric morphology . one example is @xcite who used the gemini telescope with the quirc instrument and hokupaa ao system to perform high resolution ( 0.15 ) 2.12 @xmath1 m and narrowband continuum imaging of three young pne , iras 19306 + 1407 , iras 20028 + 3910 , and iras 22023 + 5249 . they found the h@xmath0 emission primarily in the lobes or in an equatorial torus around the star . they demonstrated that with ground - based near - ir imaging one can detect and resolve structures in objects that are in the very early stages of pn formation . @xcite applied similar techniques to another young pn , iras 16342 - 3814 . they used the keck ii telescope with nirc2 and natural guide star ao system to obtain @xmath3 and @xmath4 images that show limb - brightened bipolar lobes with a corkscrew " pattern inscribed in the walls of the lobes . they conclude that this pattern is the result of a well - collimated jet with a diameter @xmath5 100 au and a precession period @xmath5 50yr . ground - based near - ir imaging has also been used in conjunction with hst ( and longer wavelength ) imaging to probe regions that are heavily extincted near the core and to trace the distribution of pah molecules and hot dust emission . @xcite used the isaac instrument on the vlt to image the bipolar pn ngc 6302 in the 3.28 @xmath1 m pah and br@xmath2 lines , as well as continuum wavelengths . the pah feature emission is found to be similar to the ionized emission , although in the pah image there is an additional local maximum in a `` spur '' of emission and a shell extending away from the core . they also used the jcmt to obtain a 450 @xmath1 m continuum image which shows an extended massive dust disk around the central core . from these data , they were able to estimate the mass of the dust and the disk , examine the complicated structure in the core , and detect a point source that may be related to the central star . @xcite performed a similar study of the bipolar pn ngc 6537 . the observations by @xcite of menzel 3 ( mz 3 ) show the power of combining narrowband images with optical and near - ir spectra . mz 3 is a bipolar nebula that is similar in many respects to m 2 - 9 , except that mz 3 is a bipolar with no detected h@xmath0 emission . with the spectra , smith used the cloudy program to model the central source temperature and determine abundances of the ejecta . the images in particular lines indicate how conditions vary across the nebula . when high spectral resolution imaging can be performed , a wealth of information can be obtained on the morphology and kinematics of the nebula . this has been demonstrated for example in the pn ngc 7027 and afgl 618 ( ( * ? ? ? * cox et al . 2002 ) ; ( * ? ? ? * cox et al . 2003 ) ) . they used the bear instrument , an imaging fourier transform spectrometer operated at the cfht that provided a spectral resolution of @xmath69 km s@xmath7 . these data allowed cox et al . to examine the kinematics of the ionized gas and molecular components , and to probe the interactions in the outflows the recent availability of facility mid - ir instruments on large telescopes has enhanced the ability to probe even deeper into obscured regions , and to detect emission from warm dust and molecules . the objects which have been most often observed are young pne which are bright in the mid - ir and their central regions are obscured by dust in the optical . the first instruments based on sensitive mid - ir array detectors were developed in the late 1980 s and were used on the large ir - optimized telescopes of that time to study this class of objects ( e.g. , ( * ? ? ? * hora et al . 1990 ) ; ( * ? ? ? * meixner et al . 1993 ) ; ( * ? ? ? * deutsch et al . 1993 ) ; ( * ? ? ? * persi et al . 1994 ) ; @xcite ; ( * ? ? ? * meixner et al . 1999 ) ) . some mid - ir imaging has continued to be performed on 3 - 4 m telescopes . for example , @xcite used timmi2 on the eso 3.6 m to image ngc 6302 , and @xcite imaged the post - agb star iras 16279 - 4757 . @xcite used mirlin on the irtf to image m2 - 9 , mz 3 , and he 2 - 104 . recently , mid - ir instruments on keck , the vlt , and gemini telescopes have been exploited to achieve higher sensitivity and resolution . @xcite used the gemini south telescope with the t - recs instrument to image hen 3 - 401 , a bipolar nebula viewed nearly edge - on , with lobes separated by a dust lane . with continuum images at 10.4 and 18.3 @xmath1 m , they constructed a color temperature map of the emission in the lobes . they obtained a narrowband image in the 11.3 @xmath1 m pah feature and determined that the pah emission is organized in concentric sets of arcs in the lobes , which suggests several ejection epochs . in another investigation of mid - ir spectral features , @xcite used the gemini north telescope and oscir to examine two proto - pn that possess the 21 @xmath1 m emission feature . they found a similar morphology in the 11.3 and 21 @xmath1 m emission , suggesting that the carriers of both features originated in the material ejected during the agb phase . in another example of a multi - wavelength approach , @xcite used archive hst optical data and near- and mid - ir data from 3 13 @xmath1 m to examine the core of the pn hen 2 - 113 . this pn had been imaged previously by @xcite who found the morphology to be bipolar , with two ring - like structures around the central star location . lagadec et al . obtained their images with several instruments ( naco , midi , isaac , and timmi ) at eso , and analyzed them in conjunction with the hst data . they determined that the pn has a `` diabolo '' structure , with the previously observed rings being the opening of two cone - like structures defining the bipolar outflow , and a dark lane between them . there are also many other structures detected , such as bright regions and spots , and filaments and holes in other parts of the lobes . the distribution of the pah emission leads them to conclude that the pahs formed more recently than the continuum - emitting dust . the installation of the nicmos instrument on hst in 1997 provided the capability for high sensitivity , diffraction - limited 1 - 2.5 @xmath1 m imaging with many narrow and broad filters , and was used for several studies of pne ( e.g. , ( * ? ? ? * sahai et al . 1998 ) ( afgl 2688 ) ; ( * ? ? ? * latter et al . 2000 ) ( ngc 7027 ) ) . the cryogen ran out prematurely early in 1999 rendering the instrument no longer functional . in early 2002 , shortly after the last iau pn symposium , a cryocooler was installed that brought the nicmos instrument back to operation . since then , several new projects have been carried out , as well as studies of data in the archive that were obtained during the original cryogen lifetime . one example of new nicmos imaging that was performed on a young pn is @xcite , who imaged the oh / ir star iras 19024 + 0044 with nicmos ( 1.1 and 1.6 @xmath1 m ) and the acs ( at 0.6 and 0.8 @xmath1 m ) . they found a compact multipolar pn with at least six elongated , limb - brightened lobes originating from the central star . the central region is brighter at the longer wavelengths , with the peak in the 1.6 @xmath1 m image positioned near the center of symmetry of the lobes . the nicmos images reveal the region near the core where there are dark lanes in the optical images . another result from new nicmos imaging is the @xcite study of several regions in ngc 7293 ( the helix ) . while the acs was imaging the central region and main ring , nicmos was used in parallel to image positions on the main ring and the halo . in this nearby pn , they resolved the h@xmath0 emission in the ring into individual molecular knots that have the appearance of small arcs with their apex pointing toward the central star . the arcs are similar to the cometary knots previously observed in the central hole , but without the long tails . at increasing radius , they found the h@xmath0 emission becomes less structured . from the h@xmath0 images , they estimate a total neutral gas mass of the pn . infrared imaging surveys such as 2mass and msx have become available since the last iau pne symposium and have provided a resource that has begun to be exploited for the study of pne . for example , phillips & ramos larios have in a series of papers ( @xcite ; @xcite ; @xcite ) used the 2mass database to study the near - ir properties of the pne in the extended source catalog , and to examine hot dust in these nebulae . they report the presence of hot dust halos for several of the pne with large @xmath8 and @xmath9 band excesses , possibly due to small grains . @xcite used optical photometry along with 2mass , msx , and iras data to examine a sample of hot post - agb candidates . they modeled the seds and derived mass loss rates , temperatures , distances , and sizes of the dust envelopes . with the launch of the _ spitzer space telescope _ , an important new tool became available for the study of evolved stars and their ejecta . the three instruments on board _ spitzer _ irac ( ( * ? ? ? * fazio et al . 2004 ) ) , irs ( ( * ? ? ? * houck et al . 2004 ) ) and mips ( ( * ? ? ? * rieke et al . 2004 ) ) provide imaging capability from 3 200 @xmath1 m . the irs is a powerful spectrograph operating in the 5 40 @xmath1 m range , and is reviewed in another paper at this symposium ( ( * ? ? ? * bernard - salas 2006 ) ) . in this review i focus on _ spitzer s _ broad - band imaging capability at 3.6 , 4.5 , 5.8 , 8 , 24 , 70 , and 160 @xmath1 m . the instruments sample a spectral range that is difficult or impossible to observe from the ground , and can achieve @xmath1jy sensitivities in a matter of minutes over large fields , making _ spitzer _ the most sensitive platform ever for probing faint compact mid - ir sources and extended emission from pne . the relatively low spatial resolution ( @xmath62 " for irac ) means that _ spitzer _ is complementary to ground - based instruments that have been used to resolve bright , compact structures . there are several large surveys already in the _ spitzer _ public archive that can be used for the study of pne . one of the largest is the glimpse project ( ( * ? ? ? * churchwell et al . 2004 ) ) which surveyed a large part of the galactic plane with irac . the mipsgal project ( ( * ? ? ? * carey et al . 2005 ) ) will map a similar area with the mips 24 and 70 @xmath1 m bands . the properties of known pne can be determined , and also searches for new nebulae performed ( e.g. , ( * ? ? ? * cohen et al . 2005 ) ) . another potentially useful data set is the sage survey of the lmc ( ( * ? ? ? * meixner et al . 2006 ) ) , which imaged a 7x7 degree region with mips and irac . source catalogs and mosaics for sage are expected to be released in late 2006 . all data can be accessed via the _ spitzer _ web site at http://ssc.spitzer.caltech.edu . or forbidden line emission from the ionized gas . in some cases where the central star was detected , the star and nebula were plotted separately.,title="fig : " ] or forbidden line emission from the ionized gas . in some cases where the central star was detected , the star and nebula were plotted separately.,title="fig : " ] the irac gto program includes a project to image 35 pne with irac . a parallel program was carried out in mips gto time by w. latter . some early results have been presented ( ( * ? ? ? * hora et al . 2004 ) ; ( * ? ? ? * hora et al . 2005 ) ; ( * ? ? ? * hora et al . 2006 ) ) , a sample are shown here . figure [ fig : colors ] shows the irac colors for a number of pne observed . the nebular colors are in general red , especially comparing the 3.6 or 4.5 @xmath1 m bands to the 5.8 and 8 @xmath1 m . m bands are mapped to blue , green , orange , and red , respectively . the image is approximately 24 @xmath10 26 arcmin in size . the cometary knots are visible inside the main ring ; the knot tips are relatively brighter in the 3.6 and 4.5 @xmath1 m bands , and the tails are brighter at 8 @xmath1 m . the nebular emission is dominated by h@xmath0 in the irac bands . ] m bands are blue , green , orange , and red , respectively . left : the dumbbell ( ngc 6853 ) . right : the ring ( ngc 6720 ) . , title="fig : " ] m bands are blue , green , orange , and red , respectively . left : the dumbbell ( ngc 6853 ) . right : the ring ( ngc 6720 ) . , title="fig : " ] the irac image of the helix is shown in figure [ fig : helix ] ( ( * ? ? ? * hora et al . 2006 ) ) . the four bands are mapped into colors of blue to red in order of wavelength . the irac images and irs spectra , along with 2.12 @xmath1 m images , confirm the results of @xcite who mapped the helix with _ iso _ and found that the mid - ir emission was dominated by lines of h@xmath0 . along with cox et al . and @xcite we find that the h@xmath0 line ratios are inconsistent with pdr models . we find that they can be fit by models of shock - excited h@xmath0 , with a small pdr component . the irac emission is clumpy in the rings , each clump appearing as a small arc pointing back toward the central star , as in the 2.12 @xmath1 m h@xmath0 images . outside of the ring , there are radial rays extending into the halo . figure [ fig : db_ring ] shows the irac images of the dumbbell ( ngc 6853 ) and the ring nebula ( ngc 6720 ) . for the dumbbell nebula , the appearance in the irac image is drastically different than in the optical . the irac emission is primarily from the roughly n - s dense equatorial region , and is dominated by the clumpy emission and radial rays that are strongest in the long wavelength channels . the appearance at 8 @xmath1 m is almost identical to the 2.12 @xmath1 m h@xmath0 image , indicating a common origin . in the ring nebula , there are similarities to the optical appearance , but the h@xmath0 emission in the irac bands highlights different parts of the nebular structure ( see also ( * ? ? ? * speck et al . 2003 ) ) . in the irac color image in figure [ fig : db_ring ] , the central region is slightly green from emission in the 4.5 @xmath1 m bandpass , possibly due to atomic lines such as br@xmath2 , [ mg iv ] and [ ar vi ] in that band . the edge of the ring and the outer halo are orange - red , consistent with emission from h@xmath0 in the 5.8 and 8 @xmath1 m bands . an early mips imaging result was reported by @xcite , who imaged ngc 2346 at 24 , 70 , and 160 @xmath1 m . the distribution of the 24 @xmath1 m emission was found to be very similar to the optical h@xmath2 emission , except for a hot dust component that peaks at the position of the central star . this dust is likely responsible for the previously observed deep fadings of the central star . the 70 @xmath1 m image shows a double - peaked morphology in the narrow waistband of the nebula , indicating a possible dust torus structure . the 160 @xmath1 m image shows that the nebula is contained in an extended cold dust envelope . infrared imaging is an important probe of the molecular and dust components of pne , as well as the ionized gas in regions that are obscured at shorter wavelengths . much of the recent work has focused on high spatial resolution studies of young pne , exploring the early development of nebula formation and searching for evidence of the processes responsible for the nebula morphology . new surveys and instruments such as those on board _ spitzer _ have recently become available and are being utilized to expand our knowledge of the formation and evolution of pne . this work is based in part on observations made with the spitzer space telescope , which is operated by the jet propulsion laboratory , california institute of technology under nasa contract 1407 . support for the irac instrument was provided by nasa under contract number 960541 issued by jpl . 2006 , in _ planetary nebulae in our galaxy and beyond _ eds . m. j. barlow & r. h. mndez , proc . 234 , this volume 2005 , _ aas _ , 207 , 6333 2004 , _ apjs _ , 154 , 322 1998 , _ apj _ , 495 , l23 2002 , _ a&a _ , 384 , 603 2003 , _ apj _ , 586 , l87 1993 , iau symp . 155 , _ planetary nebulae r. weinberger & a. acker ( dordrecht : kluwer ) , 344 2004 , _ apjs _ , 154 , 10 2003 , _ a&a _ , 404 , 305 1990 , _ apj _ , 353 , 549 2004 , apjs , 154 , 296 2006 , submitted 2004 , _ apjs _ , 154 , 18 1996 , _ apj _ , 462 , 777 2002 , _ a&a _ , 394 , 679 1997 , iau symp . 180 , _ planetary nebulae _ , eds . h. j. habing & h. j. g. l. m. lamers ( dordrecht : kluwer ) , 352 2002 , _ apj _ , 573 , 720 2006 , _ a&a _ , 448 , 203 1995 , _ apjs _ , 100 , 159 2000 , _ apj _ , 783 , 539 2004 , _ apj _ , 604 , 791 2005a , _ mnras _ , 359 , 383 2005b , _ mnras _ , 359 , 383 1993 , _ apj _ , 411 , 266 1999 , _ apjs _ 122 , 221 2005 , aj , 130 , 1784 2006 , _ aj _ , in press 2006 , _ apj _ , 640 , 353 , 1994 , _ exp . _ , 3 , 171 2005 , _ mnras _ , 364 , 849 2006 , _ mnras _ , in press 2005 , _ mnras _ , 357 , 732 2004 , _ apjs _ , 154 , 25 1998 , _ apj _ , 492 , l163 2000 , _ apj _ , 543 , 880 2005 , _ apj _ , 622 , l53 2003 , _ mnras _ , 342 , 383 2005 , _ aj _ , 129 , 969 2003 , _ pasp _ , 115 , 170 2004 , _ apjs _ , 154 , 302 2004 , _ apj _ , 616 , 1181 , 2004 , _ apjs _ , 154 , 1

new ground - based telescopes and instruments , the return of the nicmos instrument on the _ hubble space telescope _ ( hst ) , and the recent launch of the _ spitzer space telescope _ have provided new tools that are being utilized in the study of planetary nebulae . multiwavelength , high spatial resolution ground - based and hst imaging have been used to probe the inner regions of young pne to determine their structure and evaluate formation mechanisms . _ spitzer_/irac and mips have been used to image more evolved pne to determine the spatial distribution of molecular hydrogen , ionized gas , and dust in the nebulae and halos .

density fluctuations on au - size scales in the interstellar plasma may produce a host of observable effects including refractive intensity scintillations and image wander . the magnitude of these effects depends crucially upon the spectrum of the interstellar density fluctuations . if the spectrum is a power law with a spectral index less than 4 , these refractive effects will generally be masked by diffractive effects from even smaller scale density fluctuations @xcite . conversely , if the spectrum is a power law with a spectral index greater than 4 , refractive effects will dominate . for many lines of sight the density spectral index appears to be close to , but less than , 4 @xcite , with important exceptions ( e.g. , * ? ? ? * ; * ? ? ? * ; * ? ? ? * ; * ? ? ? * ; * ? ? ? complicating the effort to measure refractive effects is their generally long time scale . the relevant time scale is given by the time it takes for an au - sized density fluctuation to drift past the observer . for observations of pulsars , whose velocities can exceed 100 , the time scale is days . for observations of extragalactic sources , the relevant velocity is a combination of the earth s velocity and random interstellar motions and is more likely to be roughly 25 , meaning that the refractive time scale is months to years . the source is an ideal source for probing refractive effects . it lies on the outskirts of the cygnus superbubble @xcite , a region known to exhibit enhanced interstellar scattering @xcite . vlbi observations reveal its milliarcsecond structure to be dominated by two components separated by approximately 60 mas , thus a search for refractive image wander requires only _ relative _ position measurements . * hereafter @xcite ) obtained 0.61 ghz vlbi observations of . combined with previous measurements in the literature , they showed that scattering is moderately strong along this line of sight . they were also able to constrain the amount of differential refractive image wander between the two components . their constraint , however , is based on measurements of the separation of the components at two epochs separated by four years . if the refractive time scale is longer than four years , their constraint is weakened considerably . assuming that typical interstellar velocities along this line of sight are 50100 , @xcite argued that the refractive time scale is comparable to or less than four years . obviously , if the typical interstellar velocity is more like 25 , the refractive time scale is much longer . we have acquired a third epoch of 0.61 ghz vlbi observations of , specifically to confront the conclusions of @xcite with another epoch of observations . this third epoch is 12 to 16 yrs after the first two epochs and should allow us to place much better constraints on any refractive wander . we have also acquired simultaneous or quasi - simultaneous observations at a range of other wavelengths in order to confirm previous measurements of the strength of interstellar scattering along this line of sight . in [ sec : observe ] we describe our observations and data analysis , in [ sec : scatter ] we discuss the implications of our observations for both diffractive and refractive interstellar scattering along this line of sight , and in [ sec : intrinsic ] we discuss limits our observations place on the intrinsic structure and kinematics of the source . we present our conclusions in [ sec : conclude ] . we observed with the vlba for a total of 10 hours on 2000 july 25 . relevant observation parameters are summarized in table [ tab : log ] . 0.33 & 12 & r , l & 2.88 & 61 @xmath1 58 @ 87 & 3.2 + 0.61 & 4 & r , l & 2.88 & 27 @xmath1 19 @ 14 & 5 + 1.67 & 32 & r , l & 2.93 & 7.3 @xmath1 4.7 @ @xmath2 & 0.78 + 2.27 & 16 & r , l & 2.92 & 5.8 @xmath1 3.6 @ @xmath3 & 1.1 + 8.42 & 16 & r , l & 2.92 & 1.9 @xmath1 1.4 @ @xmath4 & 0.61 + the observation frequencies were 0.33 , 0.61 , 1.67 , 2.3 , and 8.4 ghz ; both right and left circular polarization were recorded at all frequencies . the 2.3 and 8.4 ghz observations were obtained simultaneously in `` s / x mode . '' simultaneous 0.33 and 0.61 ghz observations also were obtained by setting two of the eight baseband converters ( bbcs ) at each vlba antenna to record the two senses of circular polarization at 0.61 ghz . because of severe radio frequency interference around 0.61 ghz , filters restricted the observable bandwidth for each bbc to 4 mhz . the remaining bbcs recorded 0.33 ghz . formatter problems at the kitt peak antenna meant that only nine of the ten vlba antennas were correlated . the correlated visibilities were processed in the standard fashion within the nrao astronomical image processing system ( aips ) . fringe - fitting intervals ranged from 10 min . at 1.67 ghz to 3 min.at 0.33 and 8.4 ghz . at 0.33 and 0.61 ghz , substantial editing of the calibrated visibilities was required to remove radio frequency interference . in general the calibrated visibilities were then exported to the caltech ` difmap ` program for hybrid mapping . to ensure a robust estimate for the separation of the components ( [ sec : ref ] ) , the 0.61 ghz observations were imaged using both aips and ` difmap ` ; the 0.33 ghz observations were imaged using only aips . figure [ fig : images ] shows the images of at the various frequencies . the observed rms noise level in these images ranges from 0.61 at 8.42 ghz to 5 at 0.61 ghz and are summarized in table [ tab : log ] . the rms noise levels in our images are roughly within a factor of 23 of the expected value . using the images shown in figure [ fig : images ] as a guide , we fit the self - calibrated visibility data with multiple gaussian component models . the number of gaussian components fitted ranged from 1 at 0.33 ghz to 7 at 8.42 ghz . these models are summarized in table [ tab : models ] . below we shall make use of the fitted angular diameters . at the higher frequencies , we take the uncertainty in a fitted angular diameter to be one half of the synthesized beam ; at the lower frequencies , where a one- or two - component fit suffices , we take the uncertainties to be the square roots of the diagonal elements of the covariance matrix obtained from a least - squares fit to the visibility data ( provided by the ` uvfit ` fitting routine within aips ) ; these values are of order 0.5 mas . lcccccccc 0.33 & 2.17 & 0.0 & & 106.2 & 0.76 & @xmath5 & e + 0.61 & 2.48 & 0.0 & & 24.1 & 0.82 & 24 & e + & 0.39 & 56.1 & @xmath6 & 26.2 & 0.69 & 8 & w + & 0.11 & 32.6 & 8 & 47.5 & 0.00 & 67 & e + 1.67 & 1.75 & 59.3 & @xmath7 & 3.5 & 0.90 & @xmath8 & w + & 0.79 & 5.5 & @xmath6 & 4.2 & 0.74 & @xmath9 & e + & 0.99 & 1.3 & @xmath10 & 4.0 & 0.86 & 33 & e + & 1.06 & 3.4 & 42 & 4.9 & 0.69 & @xmath11 & e + & 0.16 & 8.9 & @xmath12 & 11.8 & 0.32 & @xmath13 & e + 2.27 & 1.97 & 0.0 & @xmath14 & 2.9 & 0.71 & @xmath15 & w + & 0.92 & 58.5 & 101 & 3.7 & 0.81 & 17 & e + & 0.58 & 53.8 & 100 & 3.3 & 0.59 & @xmath16 & e + & 0.83 & 61.5 & 97 & 4.2 & 0.54 & @xmath17 & e + & 0.12 & 52.9 & 103 & 7.5 & 0.39 & @xmath18 & e + 8.42 & 0.35 & 18.4 & @xmath19 & 0.8 & 0.54 & 84 & w + & 0.39 & 20.1 & @xmath20 & 1.0 & 0.51 & @xmath21 & w + & 0.19 & 34.9 & 103 & 2.1 & 0.64 & @xmath22 & e + & 0.19 & 40.3 & 105 & 2.1 & 0.54 & 60 & e + & 0.19 & 43.2 & 99 & 3.5 & 0.51 & @xmath23 & e + & 0.22 & 18.8 & @xmath23 & 3.1 & 0.24 & @xmath24 & w + & 0.16 & 39.0 & 102.4 & 6.3 & 0.28 & 40 & e + we now revisit the scattering properties of the line of sight to . we consider both diffractive effects , namely angular broadening , and refractive effects , namely differential image wander and refractive intensity fluctuations . we shall make the standard assumption throughout that the density fluctuations responsible for interstellar scattering can be parameterized by an exponentially - truncated power law @xmath25 here @xmath26 is the largest wavenumber on which density fluctuations occur , which is related to the smallest length scales for density fluctuations @xmath27 or `` inner scale '' as @xmath28 . the smallest wavenumber on which density fluctuations occur or the `` outer scale '' is @xmath29 . the constant @xmath30 is a measure of the level of density fluctuations and is related to the rms density as @xmath31\,{\ensuremath{c_n^2}}\ , l_0^{3-\alpha}$ ] @xcite . the power law spectral index is assumed to provide clues about the process(es ) that generate or maintain the density fluctuations . our observations allow us to measure @xmath32 , constrain @xmath30 , and indirectly place limits on @xmath27 . an infinitely - distant point source viewed through a medium filled with density fluctuations having a spectrum described by equation ( [ eqn : spectrum ] ) and a spectral index @xmath33 will be broadened to an angular diameter @xcite @xmath34 here @xmath35 is the observing frequency measured in ghz , and the scattering measure sm is the line of sight integral of @xmath30 , @xmath36 the quantity @xmath37 is the cross - over angle and describes the relative importance of the inner scale @xmath27 . it is given by @xmath38 . the constants ( 128 mas and 132 mas ) given in equation ( [ eqn : thd ] ) are those appropriate for infinitely distant sources and differ slightly from those given by @xcite who considered sources embedded in the medium . these formulae specify the diameter as the full width at half maximum ( fwhm ) of the shape of the image and that shall be the convention we adopt in reporting the measured diameters . the scattering diameter @xmath39 defines the diffractive scale @xmath40 , @xmath41 ( at observing wavelength @xmath42 ) . if the typical interferometer baseline @xmath43 is sufficient to resolve @xmath39 ( i.e. , @xmath44 ) and @xmath45 , we expect @xmath46 and @xmath47 . conversely if @xmath48 , then we expect @xmath49 and @xmath50 . therefore fitting the observed diameter as a function of frequency can constrain both @xmath27 and @xmath32 . there are alternate causes for a @xmath47 dependence . for instance , if the spectrum of density fluctuations is not a power law but a gaussian centered on a particular length scale , that can produce a @xmath47 dependence . similarly , if the density spectrum is dominated just slightly by au - size scales such that @xmath51 , that could also produce an apparent @xmath47 dependence within the measurement uncertainties . as we shall show below , @xmath52 so that we could interpret a @xmath47 dependence as resulting from a `` large '' inner scale . figure [ fig : diameter ] shows the measured angular diameters as a function of observing frequency . also shown are two curves , one for @xmath53 appropriate for a spectrum with @xmath54 and a diffractive scale @xmath40 much larger than @xmath27 and one for @xmath55 appropriate for the case in which @xmath56 . as figure [ fig : images ] demonstrates , is not only not a point source , but the two components of it can be resolved into multiple sub - components at high frequencies . a visual inspection of figure [ fig : diameter ] suggests that at frequencies below 1 ghz scattering dominates the structure of while at frequencies above 1 ghz there are clear deviations from either curve due presumably to intrinsic structure . in order to quantify this result , we have fit the measured diameters of the eastern component ( table [ tab : models ] ) with the following functional form @xmath57 here @xmath58 is the intrinsic diameter and @xmath59 is the scattering diameter , both at the fiducial frequency of 1 ghz . unlike in equation ( [ eqn : thd ] ) where we specified the dependence for the specific case of @xmath33 , here we allow the frequency dependence to be part of the fit . the frequency dependence we use is appropriate for @xmath52 . several points are in order regarding the choice of data we used . at 0.33 ghz only one component is seen ( figure [ fig : images]_a _ ) . attempts to fit the visibility data with a two - component structure suggested by the 0.61 ghz image produced a poorer fit to the data . we have subtracted a one - component model ( table [ tab : models ] ) from the visibility data and imaged the residuals . there is no indication of a second component at the location expected from the higher frequency images . we have also produced model visibility data , comprised of two components whose flux densities , diameters , and positions are consistent with those seen at higher frequencies . fitting these model data with a one - component model results in a fit nearly the same as what we find by fitting the observed visibility data . the similarity suggests that any systematic error in determining the diameter is probably no more than 1 mas . because of the self - calibration we performed , we have no absolute position information . given that the eastern component is stronger at 0.61 ghz , we have therefore assumed that the single component seen at 0.33 ghz is the eastern component . at the higher frequencies both components can be resolved into multiple sub - components . in figure [ fig : diameter ] we plot the diameters of the individual sub - components . the diameters of the individual sub - components are clearly not representative of the diameter of the entire component . therefore , as a measure of the size of the components at these frequencies , we have added the diameters of the sub - components ( table [ tab : models ] ) in quadrature . if anything , this estimate will _ underestimate _ the size of a component . however , our primary interest is not in the intrinsic structure , and this procedure suffices to obtain an estimate for the intrinsic size . is classified as a gigahertz - peaked spectrum source , and both components show a single flux density maximum near 1 ghz @xcite . accordingly , in equation ( [ eqn : fit ] ) we have assumed that the intrinsic structure has no frequency dependence . while we have not conducted extensive tests , assuming no frequency dependence produces clearly much better fits than does assuming a frequency dependence of @xmath60 , as might be expected for a homogeneous source with a peak brightness temperature @xmath61 @xcite . we have used a grid - search technique to minimize the difference , in a @xmath62 sense , between the data and the expression of equation ( [ eqn : fit ] ) for the three parameters @xmath58 , @xmath59 , and @xmath32 . we have also determined the allowed ranges for the parameters in the following manner : holding two parameters fixed at the values that minimize @xmath62 , we change the third parameter until @xmath62 changes by unity . table [ tab : fit ] summarizes the best fit value for the parameters and their allowed ranges . the best - fitting curve is also shown in figure [ fig : diameter ] . a key result of this fit is that a density spectrum spectral index of 4 is highly unlikely . this result means that the inner scale @xmath27 is substantially smaller than most baselines in the array or that @xmath63 . the typical array baseline is roughly 2000 km , so we place an upper limit of @xmath64 km . this constraint is not a serious challenge to the value estimated by @xcite of @xmath65 km . using equation ( [ eqn : thd ] ) we can also derive the scattering measure . table [ tab : fit ] also lists the values of these derived quantities . ccc @xmath58 & 3.9 mas & 3.54.3 mas + @xmath59 & 7.0 mas & 6.987.03 mas + @xmath32 & 3.52 & 3.513.53 + sm & @xmath66 + @xmath27 & @xmath67 km + the anisotropy and orientation of a scattered image can , in principle , yield information about the density structures responsible for the angular broadening ( e.g. , * ? ? ? * ; * ? ? ? * ; * ? ? ? the simultaneous low frequency observations we report here are seemingly ideal for constraining any wavelength - dependent changes in the anisotropy or orientation of , as the @xmath68-@xmath69 plane coverage should be identical ( once scaled by the ratio of the wavelengths ) . we consider first the anisotropy of the image . we find axial ratios of @xmath70 ( table [ tab : models ] ) or , in terms of the image anisotropy parameter of @xcite , @xmath71 . @xcite also provide an estimate of the image anisotropy to be expected from random fluctuations within the medium . for our observing wavelengths and scattering parameters derived above , the expected random contribution to @xmath72 is approximately 0.03 . we conclude that these image anisotropies are significant . these anisotropies are also comparable to those of other sources seen through the cygnus region @xcite . @xcite attribute the similarity of the axial ratios , between different sources at different frequencies and different epochs , to be indicative of an anisotropy in the scattering material itself . we can not conclude that the image anisotropy changes with frequency for . the formal uncertainties from the fitting of the visibility data are approximately 1% . even this small uncertainty on the angular diameters , when propagated to the axial ratios , implies an uncertainty of @xmath73 , comparable to the difference between the axial ratios at the two frequencies ( table [ tab : models ] ) . changes in the image orientation between the two frequencies may reflect changes in the orientation of the density irregularities responsible for the scattering . unfortunately , we also can not draw any conclusions about the image orientation . although the @xmath68-@xmath69 plane coverage should be similar , differences in the editing ( due to the significant levels of rfi encountered ) change the relative @xmath68-@xmath69 plane coverage significantly . an indication of the difference can be seen by inspecting the synthesized beams shown in figures [ fig : images]_a _ and [ fig : images]_b_. in particular , the synthesized beam at 610 mhz has an orientation of 14compared to an orientation for the eastern component of 24 . thus , the apparent change in orientation between 330 mhz ( @xmath74 ) and 610 mhz ( @xmath75 ) may be due largely to the differences in @xmath68-@xmath69 coverage . large scale density fluctuations may affect the image position and flux density . in this section we place constraints on the strength of refractive modulation of the image , focussing primarily on the 0.61 mhz image . density fluctuations on a scale @xmath76 , where @xmath77 is the characteristic distance to the scattering medium , will cause refractive `` bending '' and `` steering '' of the propagating rays . in turn , this will affect the angle of arrival of rays and make radio sources wander about a true or nominal position . the magnitude of this effect depends both upon the strength of scattering and the value of @xmath32 . @xcite selected because its two component structure allowed for _ relative _ position measurements to be performed , obviating the need for determining absolute positions with milliarcsecond accuracy . @xcite summarized the predictions for the amount of differential angular wander as a function of @xmath32 as predicted by various groups ( @xcite ; see appendix a of @xcite ) . they found that the rms differential refractive angular wander is @xmath78 here @xmath79 is the separation between pierce points through the scattering medium . for a double source ( like ) with a component angular separation of @xmath80 , @xmath81 . the functions @xmath82 and @xmath83 are normalization functions that differ from group to group , but typically by no more than a factor of a few . for reference , @xcite predict @xmath84 for a kolmogorov spectrum in a screen located @xmath85 kpc distant , producing an angular broadening of @xmath39 mas , and observed at a wavelength of @xmath86 cm . in general if @xmath87 refractive effects like angular wander dominate over diffractive effects like angular broadening . thus one would expect to see the apparent position of a source wander by more than the width of its scattering disk . if @xmath52 , the converse is true . table [ tab : sep ] summarizes the 0.61 mhz measurements of the angular separation between the two components of . we have estimated @xmath88 using two different methods . henceforth we shall also distinguish between the ensemble average expected differential angular wander , @xmath88 , and the quantity estimated from the separation measurements , @xmath89 . first , we calculated @xmath89 using the standard estimator for the variance and using the three values in table [ tab : sep ] . this estimate is @xmath90 mas . second , we estimated @xmath89 to be comparable to the maximum difference between component separations at the different epochs , @xmath91 . this estimate is @xmath92 mas . lcc 1984 august & 60 @xmath93 3 & @xcite + 1988 june & 56 @xmath93 2 & @xcite + 2000 july & 56.1 @xmath93 1.0 & this work + @xmath89 & 2.3 mas + @xmath91 & 4 mas figure [ fig : wander ] shows @xmath88 as a function of the density spectral index @xmath32 , as predicted by @xcite , @xcite , and @xcite . we also plot our observational limits @xmath89 , @xmath94 , and @xmath91 . in producing figure [ fig : wander ] we have assumed @xmath95 kpc . we have considered @xmath88 as a function of both @xmath77 and @xmath32 . however , the dependence on @xmath77 is fairly weak , @xmath96 for @xmath54 . reasonable ranges for @xmath77 produce little difference in @xmath88 . the value @xmath97 kpc is motivated by the distance to the cygnus superbubble @xcite , through which the line of sight to passes . figure [ fig : wander ] shows clearly that along this line of sight the upper limits on @xmath88 constrain @xmath52 . the largest allowed value , @xmath98 occurs if we adopt an upper limit of @xmath94 and use the expression for @xmath88 from @xcite . using a more stringent limit on the differential angular wander , @xmath91 , the expressions for @xmath88 from @xcite or @xcite we find @xmath99 . we adopt @xmath33 , as a limit based on @xmath89 we consider to be overly strict . the standard estimator for the variance , which we have used in determining @xmath89 , assumes that the measurements are independent . in this case the independence of the various measurements can be assessed by comparing the interval between the different measurement epochs with the refractive time scale , @xmath100 where @xmath69 is the bulk velocity of the material . @xcite assumed @xmath101100 , for which @xmath1024 yr . in this case , all three measurement epochs ( table [ tab : sep ] ) could be considered independent , though the first two only marginally so . however , if the characteristic velocity of the scattering medium is smaller , by as little as a factor of 2 , the refractive time scale would be long enough that the first two epochs ( 1984 august and 1988 june ) could not be considered independent . if the characteristic velocity is as small as 10 , then less than one refractive time has elapsed since the first observation and none of these observations can be considered to be independent . even if this was the case , we would expect to see some change over the 12 yr time span separating the second and third epochs ( 1988 june and 2000 july ) . that essentially no change in the angular separation is seen indicates that @xmath91 provides a reasonably stringent upper limit on @xmath88 . in concert with refractive wandering , the large - scale density fluctuations will also produce intensity fluctuations as more or fewer rays are `` steered '' into the line of sight . in the case of , this will produce independent variations in the flux density of its two components . @xcite compared the flux densities of the two components between their observations and those of @xcite . they found that the flux density of the components was consistent with no change in the 4 yr between 1984 august and 1988 june . table [ tab : flux ] summarizes these earlier measurements and those reported here . lcccc 1984 august & 3.8 & 0.6 & 0.16 & @xcite + 1988 june & 3.9 @xmath93 0.1 & 0.6 @xmath93 0.1 & 0.15 @xmath93 0.03 & @xcite + 2000 july & 2.864 @xmath93 0.006 & 0.374 @xmath93 0.014 & 0.13 @xmath93 0.01 & this work + because of changes in telescopes , receivers , correlators , and possible intrinsic changes , we do not compare the absolute flux densities of these earlier epochs to our measurements . rather we compare the flux density ratio between the two components . as table [ tab : flux ] shows , the western component has remained at a flux density of approximately 15% that of the eastern component for the past 15 yr . @xcite present expressions for the rms refractive intensity fluctuation @xmath103 as a function of density spectral index @xmath32 ( see also * ? ? ? * ) . in general , @xmath104% for @xmath52 and @xmath105% for @xmath87 . we determine an observed value @xmath106% from the flux density ratios in table [ tab : flux ] , suggesting @xmath52 . for @xmath52 , the strong scattering , i.e. , large sm , determined from the observed scattering diameter ( table [ tab : fit ] ) means that the rms refractive intensity fluctuation will be only a slowly - changing function of @xmath32 . from our observed value of @xmath103 we find ( * ? ? ? * equation 3.1.5 ) @xmath107 , consistent with the value found by fitting the angular diameters ( table [ tab : fit ] ) . the pulsar ( 87 from ) has been the subject of many monitoring programs designed at least in part to measure refractive scattering along the line of sight to it . in all cases , it is found that diffractive scattering dominates refractive scattering , as we find for the line of sight to . @xcite used dynamic spectra obtained at 0.41 mhz to measure the frequency drift rate and estimated that the diffractive scattering angle was at least 5 times that of the refractive scattering angle . using a structure function analysis of a 0.43 ghz flux density monitoring program , @xcite find diffractive scattering to dominate over refractive scattering . @xcite monitored the pulsar s flux density at 0.33 mhz and estimated the diffractive and refractive scattering angles toward this pulsar . they found that the diffractive scattering angle was roughly 10 times larger than the refractive scattering angle . they also estimated a density spectrum spectral index of @xmath108 . @xcite were unable to observe any refractive modulations of the pulsar s flux density in their multi - frequency monitoring program , consistent with diffractive scattering dominating on this line of sight . a key assumption in our analysis of the differential image wander is that there is little intrinsic change in the separation of the components . given that on milliarcsecond scales , many sources show evidence of jets and bulk motion , this assumption clearly must be justified . we have compared our 1.67 ghz observations with those of @xcite . this comparison is somewhat difficult because , in general , different antennas at different locations were used in the two vlbi arrays . thus , this comparison is necessarily crude , but it will be sufficient to show that our assumption is reasonable . @xcite cite a separation of 60 mas between the two components from observations in 1979 september . if we fit our 1.67 ghz observations with only two components , we find a separation of 58 mas , _ less _ than that of @xcite . even allowing for differences in arrays and uncertainties in the fitting , we conclude that any intrinsic change in the separation between the two components is probably less than 1 mas . over the 20.8 yr separating these measurements , any intrinsic motion is probably less than 0.05 mas yr@xmath109 . at a redshift of 0.354 for @xcite and for an assumed hubble constant of 65 km s@xmath109 mpc@xmath109 , this proper motion corresponds to a projected linear separation velocity of @xmath0 . our limit is similar to that found by @xcite for , a source with a similar compact double structure . we have conducted a multi - frequency suite of observations on the source . we have used these observations to confirm and extend previous conclusions , principally those of @xcite , regarding interstellar scattering along this line of sight . our 0.61 mhz observations form the third epoch of vlbi observations at this frequency . our observations are separated by 12 to 16 years from the previous two epochs . as do previous observations , we find the structure of at this frequency to be dominated by two components approximately 56 mas apart . within the uncertainties of the various measurements , this separation has remained unchanged for the past 16 years . we can place a reasonably strict limit of 4 mas on any differential image wander caused by refractive interstellar scattering . in turn , this limit implies that the electron density power spectrum along this line of sight has a spectral index near the kolmogorov value , with a value of 4 being highly unlikely . as the diffractive scattering diameter of the source at this frequency is 21 mas , we conclude that diffractive scattering dominates along this line of sight . the most significant source of uncertainty in this limit is probably the velocity at which the scattering material is drifting past the line of sight . a `` high '' velocity of 100 would mean that the separations measured at the three epochs are independent . a `` low '' velocity of 10 would mean that none of the epochs are independent . even if the velocity of the scattering material is low , the separation between our observations and the previous ones is probably long enough that , if refractive scattering were important on this line of sight , some change in the apparent separation of the components would be expected . nonetheless , future observations of at 0.61 ghz or similar observations of other sources on lines of sight for which the refractive time scale could be estimated would be useful . our observations are in good agreement with a variety of observations on the pulsar ( line of sight 87 from ) . these observations suggest that diffractive scattering also dominates refractive scattering along the line of sight to the pulsar . our quasi - simultaneous observations range from 0.33 to 8.4 ghz . we have used these multi - frequency measurements to constrain the frequency dependence of the angular diameter of one component of . at frequencies below 1 ghz , the structure of the eastern component of is dominated by scattering . fitting for both the density spectrum spectral index @xmath32 and the scattering diameter @xmath39 , we find @xmath110 with the value of 4 again highly unlikely . at a nominal frequency of 1 ghz , we find the scattering diameter to be @xmath111 mas . we also place a conservative upper limit on the density spectrum inner scale of @xmath112 km . we also compared our 1.67 ghz observations to those of @xcite , acquired approximately 21 years previously . we find no evidence for any change in the separation at this frequency . this places a limit on the projected linear separation velocity of the two components of @xmath0 . the national radio astronomy observatory is a facility of the national science foundation operated under cooperative agreement by associated universities , inc . basic research in radio astronomy at the nrl is supported by the office of naval research .

we present multi - frequency observations with the very long baseline array of the compact double radio source . our observations are at 0.33 , 0.61 , 1.67 , 2.3 , and 8.4 ghz , with the 0.61 ghz observations forming the third epoch of observation of this source at that frequency . at 0.61 ghz , the structure of is dominated by two components 56 mas apart . within the uncertainties of the various measurements , this separation has remained unchanged for the past 16 years . any differential image wander caused by refractive interstellar scattering is less than 4 mas . both the lack of differential image wander and the frequency dependence of the angular diameter of below 1 ghz indicate that the electron density power spectrum along this line of sight has a spectral index near the kolmogorov value , with a value of 4 being highly unlikely . we conclude that diffractive scattering dominates along this line of sight ; results in the literature indicate that this conclusion also holds true for the line of sight to the pulsar ( 87 from ) . comparison of our 1.67 ghz observations with those obtained 21 years previously place a limit on the projected linear separation velocity of the two components of @xmath0 .

Luke Gatti, the former UConn student who gained internet infamy when a video of his obscenity-laced tirade to a cafeteria worker about his need for a bacon jalapeño macaroni and cheese went viral on YouTube, has been arrested again in Florida. Luke Gatti's latest arrest occurred May 27 at the Wellness Resource Center, a treatment facility for people who have drug addictions and mental health disorders. The staff called police after Gatti returned to the facility from a detox center in Fort Lauderdale, where he was being treated for his addiction to alcohol and drugs, according to a Boca Raton Police Department incident report. The charges in Florida include battery on an officer and resisting an officer with violence. Gatti, 20, of Bayville, N.Y., is on probation in Connecticut until Dec. 19 as a result of his arrest in the Storrs case. In December 2015, Rockville Superior Court Judge John B. Farley granted Gatti's request for accelerated rehabilitation, a special form of probation that would allow the Connecticut criminal charges against Gatti to be dismissed if he completed a year of probation without further arrest. The Connecticut probation is now in jeopardy and Gatti could again face the criminal charges related to the UConn incident. Former UConn student Luke Gatti apologizes in court on Monday. He was granted probation after a tirade over jalapeno macaroni and cheese at the school this fall. Former UConn student Luke Gatti apologizes in court on Monday. He was granted probation after a tirade over jalapeno macaroni and cheese at the school this fall. SEE MORE VIDEOS In Florida, police were called to the Wellness Resource Center by staff who were concerned about Gatti's well-being. During a medical exam following his return to the Wellness Resource Center from the detox facility, Gatti was in pain and his vital signs were elevated, according to the police report. Doctors determined that he was going through withdrawal. Gatti asked for medication to ease the symptoms, the doctor refused, and Gatti became angry and left the facility, police said. "He was agitated and stated he was in pain and could not handle it anymore," the report reads. He left the facility without shoes, but returned several hours later to retrieve his belongings, and then he screamed at center staff to give him his property and was angry and agitated, according to the police report. When the officers told Gatti they were concerned about his safety and wanted to help, he told them he did not want their help, the report says. "He then made statements that he did not care if he got hurt or if he hurt himself and wanted to be left alone," the report reads. Gatti then tried to leave, and officers then decided to take him into protective custody. Gatti resisted the officer's, struck one in the hand, then struggled with another causing them both to fall backwards through a door, according to the report. Police then were able to handcuff him. While in custody in a police car and later at a hospital, Gatti made suicidal statements, including, "I just want to die, I just want to die," according to the report. "He advised he needs drugs and alcohol to feel better and always has suicidal thoughts and dreams of people hurting him," the report says. "He also asked me to do him a favor and shoot him with my duty weapon." Gatti was released from jail on May 31 after posting bail. Gatti's struggle with alcohol and other substances has become well-known because of the YouTube video, his arrest by UConn police and previous encounters with police in Amherst, Mass., when he attended the University of Massachusetts. In a subsequent YouTube video, Gatti apologized for his conduct at UConn and then traveled to South America to meet with David Robinson, the UConn student union manager on whom Gatti heaped abuse. Gatti's conduct after the UConn incident, which included intensive treatment for his substance abuse issues, gave the judge in Rockville a reasonable belief that Gatti was on the road to recovery. In granting accelerated rehabilitation, Farley ordered continued substance abuse treatment and community service during probation. Because of the Storrs video, the judge said Gatti had been subjected to "excruciating and humiliating publicity" for which "he has only himself to blame." "But he has paid a big price," Farley continued. "And the court does believe that will serve as a deterrent to future offenses. I would say it's fair to assume that any future brushes with the law Mr. Gatti has will bring more unwanted publicity to him." The UConn video, taken Oct. 4, showed Gatti engaged in a prolonged argument with the Student Union manager before another worker stepped in to subdue him, clearing the way for his arrest. Gatti continued to be uncooperative once in the custody of UConn police. "I've got nothing to defend," Gatti said in court in December. "I'm entirely ashamed of my actions. That's pretty much it." ||||| FILE - This undated file photo provided by the University of Connecticut police department shows Luke Gatti, of Bayville, N.Y. Gatti, a former University of Connecticut student who went on a drunken,... (Associated Press) FILE - This undated file photo provided by the University of Connecticut police department shows Luke Gatti, of Bayville, N.Y. Gatti, a former University of Connecticut student who went on a drunken,... (Associated Press) BOCA RATON, Fla. (AP) — A former University of Connecticut student who went on a drunken, obscenity-laced tirade about jalapeno-bacon macaroni and cheese has been arrested in Florida after an altercation with a police officer. Luke Gatti was charged May 28 in Boca Raton with battery on an officer and resisting an officer with violence. A message left at Gatti's home Tuesday wasn't immediately returned. Last year, the 20-year-old former UConn student from Bayville, New York, was arrested over his Oct. 4, 2015, outburst in the Student Union. He ranted at and shoved a university food service supervisor for refusing to sell him the macaroni and cheese. The altercation was caught on video and was widely viewed online. Gatti was put on probation and released his own video in which he apologized for his actions.

– A former University of Connecticut student who went on a drunken, obscenity-laced tirade about jalapeno-bacon macaroni and cheese has been arrested in Florida after an altercation with a police officer, the AP reports. Luke Gatti was charged May 28 in Boca Raton with battery on an officer and resisting an officer with violence. According to the Hartford Courant, the incident took place at a treatment facility for people dealing with drug addiction and mental illness. Last year, the 20-year-old was arrested over his Oct. 4, 2015, outburst in the Student Union. He ranted at and shoved a university food service supervisor for refusing to sell him the macaroni and cheese. The altercation was caught on video and was widely viewed online. Gatti was put on probation and released his own video in which he apologized for his actions.

small bowel intussusception is a rare condition in adulthood , with benign and malignant gastrointestinal lesions being the main causative points . the possibility of gastric outlet obstruction and advanced malignant disease often indicate for an urgent surgical treatment . we present the case of a 75-year - old male who suffered from small bowel intussusception due to a neuroendocrine carcinoma ( nec ) . we will also review the literature regarding management of both medical conditions and their relation . a 75-year - old caucasian male was referred to our department due to black stool during defecation and episodes of cramp - like abdominal pain for the past 2 months . his medical history included hypertension and chronic obstructive pulmonary disease ( copd ) , while he also reported treatment for a peptic ulcer at the age of 40 and appendectomy at a younger age . laboratory exams revealed a hematocrit of 28.4 mg / dl with hemoglobin of 8.4 mg / dl . a fecal occult blood test was positive , and gastroscopy was performed , which proved negative for upper gi hemorrhage , active peptic ulcer or stomach neoplasia . patient further underwent capsule endoscopy test , with the results uncovering the presence of two neoplasms in the proximal jejunum , one of them with an ulcerated surface and signs of active bleeding . a computed tomography ( ct ) scan was significant for intussusception of the proximal jejunum , with the presence of an intraluminal mass causing partly bowel stenosis ( fig . the presence of copd was a contradiction for general anesthesia and laparoscopic surgery , so spinal anesthesia was applied and a small supra - infraumbilical incision was executed . upon entering the abdominal cavity , manipulation of the jejunum was easily performed . the intussuscepted part was located in the proximal jejunum , with the presence of two additional swollen lymph nodes in its mesentery . the pathologic part was excised along with the lymph nodes , and a side - to - side anastomosis was performed ( figs 2 and 3 ) . figure 2:(a , b ) small bowel intussusception located in the proximal jejunum.figure 3:(a , b ) excised specimen demonstrating two necs responsible for the intussusception . pathology report demonstrated two large cell , low differentiated , stage iiib according to enets , necs of the jejunum ( pt3n1a ) . immunohistochemical report was positive for synaptophysine and chromogranin a ( cga ) , as well as ki-67 proliferative activity . he was discharged on the fourth postoperative day , with a hematocrit of 31.2 mg / dl . he started adjuvant chemotherapy with somatostatin analogues ( ssa ) , while at 6-month follow - up no metastases were observed . small bowel intussusception is defined as the distal protrusion of a small bowel loop ( intussusceptum ) inside the lumen of an adjacent bowel segment ( intussuscipiens ) along with its mesentery . it is a rare medical condition in the general population with the vast majority of cases ( 95% ) being observed during the first trimester of infancy . in adulthood , intussusception is encountered in ~2% of gastric outlet obstruction cases [ 1 , 2 ] . it is classified according to etiology to benign , malignant and idiopathic , with metastatic tumors ( melanoma , lung cancer and breast cancer ) and gastrointestinal malignancies or benign neoplasms ( polyps ) being the leading points . clinical manifestation is often obscure with symptoms being associated with partial or complete bowel obstruction . vague abdominal pain , nausea or episodes of vomitting are usually observed , while patients can also exhibit episodes of abdominal distension and ileus . abdominal cramp - like pain , or constipation and weight loss may also be present , suspicious for an underlying malignant pathology [ 3 , 4 ] . computed tomography is the modality of choice for diagnosis of an intussuscepted bowel loop , with a sensitivity and specificity of ~80% and 100% , respectively . depending on sagittal or axial view , findings may include the presence of concentric rings due to duplication of small bowel layers ( doughnut or target sign ) , or a sausage shaped mass [ 3 , 5 , 6 ] . u / s scan is also useful for identification of intussuscepted bowel with the typical target sign . diagnosis is usually set intraoperatively , because of the nonspecific clinical symptoms and non - pathognomonic radiological findings . treatment can be either conservative , in cases which no evident pathology is present , or surgical excision of the pathologic bowel part through open or laparoscopic surgery . since malignancies are the primary cause for most intussusception cases , most surgeons agree to a surgical approach , with ~60% of interventions being executed in an emergency setting [ 1 , 3 ] . reduction of the small bowel in order to avoid surgery and save bowel length is dangerous due to the possibility of bowel perforation and migration of malignant cells . neuroendocrine neoplasms ( nens ) of the small intestine are rarely associated with intussusception in the medical literature . up to 10% of patients may exhibit symptoms typical of carcinoid syndrome consisting of ( i ) skin flushing , ( ii ) diarrhea or cramp - like abdominal pain and ( iii ) musculoskeletal symptoms . adjuvant therapy with ssa is recommended , markedly improving patients quality of life , with a significant reduction of carcinoid syndrome symptoms in up to 75% of cases . chemotherapy is a contradiction in cases of well - differentiated or metastatic neoplasms , while patient s follow - up includes ct scan every 312 months and control of cga and 5-hydroxyindoleacetic acid levels . in a recent publication , kadowaki et al . presented a case of gastroduodenal intussusception due to a collision tumor , consisting of adenocarcinoma and a nec . in another report , lachhab et al . described the case of a patient with small bowel intussusception due to a neuroendocrine tumor . in the first case , patient underwent surgical resection with no adjuvant chemotherapy and metastatic hepatic and splenic tumors after 6 months , while in the second case patient underwent excision of the intussuscepted bowel loop with no further therapy , and no metastases reported at 6-month follow - up [ 9 , 10 ] . in conclusion , although necs and intussusception of the small intestine are rarely associated , the tumor s aggressiveness and possibility of complete gastric outlet obstruction suggest for an aggressive therapeutic approach with close follow - up monitoring . written informed consent was obtained from the patient for publication of this case report and corresponding images .

abstractintussusception of the small bowel is an uncommon condition , with the majority of cases being observed during infancy . a number of points are responsible , with benign and malignant lesions of the small intestine being the most common . herein , we present the case of a 75-year - old male patient with vague abdominal pain and black stool during defecation , who underwent surgery due to jejunal intussusception . pathology report demonstrated a neuroendocrine carcinoma as the underlying cause for his condition , with no additional metastases during the initial diagnosis . although a conservative approach for management of intussusception is viable , the possibility of gastric outlet obstruction and the presence of malignancy as the primary point usually lead to urgent surgery . in the case of malignancy , adjuvant chemotherapy or additional symptomatic therapy with close follow - up may be required depending on tumor s grade and aggressiveness .

the major therapeutic goals in mucogingival surgery are correction of esthetic problems , hypersensitivity and/or shallow root carious lesions . several techniques such as the free gingival graft,[13 ] laterally repositioned flap,[46 ] coronally positioned flap and double papilla graft have been proposed for the correction of these mucogingival deformities . originally sullivan and atkins(1968 ) described a technique for coverage of exposed root surfaces using the free gingival autogenous graft . the graft survival over large expanses of avascular root surfaces was however unpredictable , complete root coverage was hence rarely achieved . moreover , the procedure involved two surgical sites , creating a large denuded area on the palate that resulted in considerable postoperative discomfort to the patients . the inconsistent color blending of the graft with adjacent gingival tissues limits its use in esthetically sensitive areas . karring and co - workers demonstrated that the underlying connective tissue has a direct bearing on the type of epithelium that is superimposed upon it . edel showed that a significant increase in the volume of gingiva can be achieved by grafting gingival connective tissue alone . langer and langer described the subepithelial connective tissue graft technique in root coverage on both single and multiple adjacent teeth . the advantage of this graft is the double blood supply from the overlying flap and palatal connective tissue , which maximize the graft survival . several modifications of this technique have been proposed and connective tissue grafts are considered the gold standard for treatment of gingival recession.[1316 ] however , this technique involves a certain degree of discomfort to the patient because an additional palatal donor site has to be prepared , increasing the risk of postoperative pain and hemorrhage . the post - operative discomfort has been considerably minimized through not fully eliminated by more conservative methods described by bruno and hurzeler and weng . yukna et al , demonstrated that allogenic freeze - dried skin graft is a clinically acceptable and beneficial grafting material for the treatment of mucogingival problems . recently , an acellular dermal matrix graft has been used as a substitute for the palatal donor sites to increase the width of keratinized tissue around the teeth and implants,[2022 ] for the treatment of alveolar ridge deformities and for root coverage procedures.[2325 ] processing of the dermis obtained from human donor removes all cells , leaving a structurally intact connective tissue matrix composed of type - i collagen . harris reported the use of this acellular dermal matrix graft with coronally positioned flap for the treatment of gingival recession . the acellular dermal matrix consistently integrated into the host tissue , maintaining structural integrity of the tissue and revascularized via preserved vascular channels . the color match obtained was also reported to be comparable to that of the connective tissue graft . most of the information in the literature related to colour match has been derived from subjective assessment of the postoperative results by the clinician . the patient perception of postoperative esthetics with soft tissue grafts including alloderm has not been extensively studied , particularly in populations with high degree of melanin pigmentation . visual analog scale ( vas ) has been used to provide a measurable scale to evaluate subjective phenomena such as pain , esthetics , etc . the aim of this study was to evaluate the effectiveness of an acellular dermal matrix ( alloderm ) graft for root coverage procedures and to objectively analyze the post - operative esthetics using a vas . the study population consisted of male and female patients , aged 20 - 50 years with aesthetic problems due to the exposure of recession defects while smiling . pre operative facial view of gingival recession the patients agreed to the study protocol and informed consent was obtained prior to treatment . the inclusion criteria are ( 1 ) the presence of at least one miller 's class i or class ii gingival recession , ( 2 ) facial recession of maxillary and mandibular anteriors . the exclusion criteria included ( 1 ) the presence of severe cervical abrasion / root caries , ( 2 ) the presence of abnormal frenal attachment , ( 3 ) current smokers , ( 4 ) medically compromised patients . the patients initially completed a plaque control program , till all of them achieved a full mouth plaque score ( fmps ) < 25% . the following clinical measurements were taken by a single examiner at base line at the mid - buccal point of the involved tooth like probing pocket depth ( ppd ) , gingival recession ( gr ) , and clinical attachment level ( cal ) . all the measurements were made with a william 's periodontal probe ( hu - friedy ) . first , an intracrevicular incision was made through the bottom of the crevice and horizontal incision was placed at the level of cementoenamel junction ( cej ) extending 3 mm on either side of the involved tooth including their papilla . two vertical incisions were placed from end point of horizontal incision to the alveolar mucosa to establish a trapezoidal flap [ figure 2 ] . line diagram depicting the incisions a split thickness flap was elevated and all muscle interferences were eliminated in order to facilitate its coronal advancement . the root surface was mechanically treated with gracey curettes followed by conditioned with 1ml tetracycline hydrochloride solution for 3 minutes with subsequent rinsing with saline [ figure 3 ] . split thickness trapezoidal flap is elevated the acellular dermal matrix allograft was aseptically rehydrated in sterile saline , according to the manufacturer 's instructions . the graft was trimmed to a shape and size designed to cover the root surface upto cej and the surrounding bone . the basement membrane side was placed adjacent to bone and tooth , and the connective tissue side was placed facing the flap , as per previous studies . the graft was sutured over the defect with 5 - 0 bioabsorbable sutures [ figure 4 ] , followed by coronally advancement of the elevated flap and sutured . the area was reexamined to ascertain that none of the graft was visible and that the flap was sutured without tension [ figure 5 ] . initial stabilization of the alloderm coronal repositioning of the flap with complete closure all patients were instructed to discontinue tooth brushing and to avoid trauma ( or ) pressure at the surgical site . a 0.12% chorhexidine digluconate mouth rinse was prescribed 2 times daily for 15 days , and analgesics and antibiotics were prescribed for 7 days . the patients were instructed to clean the surgical site with a cotton pellet soaked in a 0.12% chorhexidine digluconate solution 3 times daily for 10 days . after this period , they resumed mechanical tooth cleaning of the treated areas using a soft toothbrush and a careful roll technique . the patients were recalled for plaque control prophylaxis after 2 and 4 weeks , followed by monthly upto 4 months ; then every 3 months for 1 year . the following post operative measurements were taken by the same examiner at the end of 3 months [ figure 6 ] and 12 months [ figure 7 ] period at the mid - buccal point of the involved tooth like probing pocket depth ( ppd ) , gingival recession ( gr ) , clinical attachment level ( cal ) . postoperative facial view at the end of 3 month ( compare with figure 1 ) postoperative facial view at the end of 12 month ( compare with figure 1 ) in order to determine the colour match , the examiner fixed a 0 - 10 scale criteria , in that 0 score was no colour match and 10 score was absolute colour match . the scoring was done at the end of 3 months and 12 months in all the patients . in order to reduce observer bias , every patient was given the same scale to rate his personal satisfaction with the colour match after treatment with alloderm . the results were analyzed statistically using the analysis of variance ( anova ) and paired t - test to estimate the mean root coverage and the color match . the following clinical measurements were taken by a single examiner at base line at the mid - buccal point of the involved tooth like probing pocket depth ( ppd ) , gingival recession ( gr ) , and clinical attachment level ( cal ) . all the measurements were made with a william 's periodontal probe ( hu - friedy ) . first , an intracrevicular incision was made through the bottom of the crevice and horizontal incision was placed at the level of cementoenamel junction ( cej ) extending 3 mm on either side of the involved tooth including their papilla . two vertical incisions were placed from end point of horizontal incision to the alveolar mucosa to establish a trapezoidal flap [ figure 2 ] . line diagram depicting the incisions a split thickness flap was elevated and all muscle interferences were eliminated in order to facilitate its coronal advancement . the root surface was mechanically treated with gracey curettes followed by conditioned with 1ml tetracycline hydrochloride solution for 3 minutes with subsequent rinsing with saline [ figure 3 ] . split thickness trapezoidal flap is elevated the acellular dermal matrix allograft was aseptically rehydrated in sterile saline , according to the manufacturer 's instructions . the graft was trimmed to a shape and size designed to cover the root surface upto cej and the surrounding bone . the basement membrane side was placed adjacent to bone and tooth , and the connective tissue side was placed facing the flap , as per previous studies . the graft was sutured over the defect with 5 - 0 bioabsorbable sutures [ figure 4 ] , followed by coronally advancement of the elevated flap and sutured . the area was reexamined to ascertain that none of the graft was visible and that the flap was sutured without tension [ figure 5 ] . initial stabilization of the alloderm coronal repositioning of the flap with complete closure all patients were instructed to discontinue tooth brushing and to avoid trauma ( or ) pressure at the surgical site . a 0.12% chorhexidine digluconate mouth rinse was prescribed 2 times daily for 15 days , and analgesics and antibiotics were prescribed for 7 days . the patients were instructed to clean the surgical site with a cotton pellet soaked in a 0.12% chorhexidine digluconate solution 3 times daily for 10 days . after this period , they resumed mechanical tooth cleaning of the treated areas using a soft toothbrush and a careful roll technique . the patients were recalled for plaque control prophylaxis after 2 and 4 weeks , followed by monthly upto 4 months ; then every 3 months for 1 year . the following post operative measurements were taken by the same examiner at the end of 3 months [ figure 6 ] and 12 months [ figure 7 ] period at the mid - buccal point of the involved tooth like probing pocket depth ( ppd ) , gingival recession ( gr ) , clinical attachment level ( cal ) . postoperative facial view at the end of 3 month ( compare with figure 1 ) postoperative facial view at the end of 12 month ( compare with figure 1 ) in order to determine the colour match , the examiner fixed a 0 - 10 scale criteria , in that 0 score was no colour match and 10 score was absolute colour match . the scoring was done at the end of 3 months and 12 months in all the patients . in order to reduce observer bias , every patient was given the same scale to rate his personal satisfaction with the colour match after treatment with alloderm . the results were analyzed statistically using the analysis of variance ( anova ) and paired t - test to estimate the mean root coverage and the color match . at base line , a mean gingival recession was 2.501.09 mm , a mean probing pocket depth was 1.50.52 mm and a mean clinical attachment level was 4.031.23 mm , were recorded . at the end of 3 months , the mean recession reduced from 2.501.09 mm to 0.470.83 mm , the probing pocket depth also reduced from 1.530.52 mm to 1.270.37 mm and clinical attachment level increased from 4.031.23 mm to 1.700.86 mm . at the end of 12 months , the mean recession depth was reduced from 2.501.09 mm to 0.470.64 mm , probing pocket depth reduced from 1.530.52 mm to 1.300.41 mm and clinical attachment level increased from 4.031.23 mm to 1.500.85 mm . on statistical analysis there was significant reduction in gingival recession and clinical attachment gain at 3 months , but there was no statistical significance improvement between 3 months to 12 months interval [ table 1 ] . base line , end of 3 month and 12 month parameters the mean root coverage was 85.5621.70 and 83.3321.82% at the end of 3 and12 months respectively . 9 out of 15 sites , 9 sites showed100% root coverage at the end of 12 months [ table 2 ] . mean root coverage at end of 3 and 12 month the colour match of surgical site was examined at the end of 3 months and 12 months using the vas . a score of 5.730.70 and 6.870.83 was obtained by the periodontist at the end of 3 and 12 months ; respectively .a statistically significant improvement was seen between the 3 and 12 month scores . the individual patient 's vas score was 7.931.03 and 8.130.99 at the end of 3 and 12 month , respectively . there was no significant difference between the 3 and 12 month scores [ table 3 ] . autogenous connective tissue grafts have been extensively used for root coverage procedures in teeth and implants . however , the necessity for a second surgical site and volume of graft material available are potential drawbacks when connective tissue grafts are used in the treatment of multiple gingival recessions . harris 's study promised that the use of acellular dermal matrix graft would improve the gingival color , reduce patient morbidity , provide uniform thickness of material , and eliminate the need for multiple surgeries because of unlimited availability . he further reported that the results obtained for the treatment of gingival recessions with alloderm was comparable to that obtained with connective tissue grafts . the surgical protocol the uniformly good root coverage obtained in this study was in accordance with previous reports and confirm alloderm 's potential as a reliable alternative to connective tissue graft . henderson et al , reported that sites treated with alloderm had resulted in defect coverage of 95% and 90% defect coverage was obtained 80% of the time . although this root coverage compares unfavorably with the previous report , 9 of the 15 sites exhibited complete ( 100% ) root coverage . in two of the fifteen sites the results of these two sites are largely responsible for the comparatively lesser degree of root coverage obtained in this study . as all surgical procedures were performed by a single operator , factors such as experience of the clinician and technique sensitivity are unlikely to be the cause of this relatively poor coverage in these two sites . these two sites , however , exhibited attachment loss greater than 6 mm and we suggest that the initial recession depth may have a greater influence on the treatment outcome than previously reported . there was no significant difference in any of the clinical parameters measured at the 3 month and 12 month interval . the results clearly indicate that the recession coverage obtained with alloderm may be successfully maintained over a prolonged period of time , provided patients exhibit good plaque control . borghetti and gardella documented that creeping attachment may continue for 1 year post operatively , when thick grafts were used . henderson et al , reported that no creeping attachment was achieved in alloderm cases from 2 to 12 months . in this study , there was no statistically significant creeping attachment between the 3 and 12 month interval . however , 4 patients did show a 1 mm improvement in attachment from the 3 to 12 month . the ethnic south indian population from where the patient pool was chosen although racial difference in pigmentation of gingiva has been previously documented , its influence on the colour match following soft tissue grafts has not been extensively studied . it has been reported that alloderm did not support keratinization of the overlying epithelium ; however , its ability to induce melanization is not known . in this study we observed that 1 month post operatively , all the gingival sites were devoid of pigmentation ( data not shown ) . by the 3 month ; patients expressed high degree of satisfaction with the postoperative esthetics in the grafted sites on the vas scores . it was noticeable though , that the periodontist 's scores were consistently lower than that of the patients . the periodontist felt that the absence of normal pigmentation resulted in a mild pallor of the grafted sites , which detracted its colour match with the adjacent sites . thus , patients seemed happier with the depigmented appearance than the periodontist , perhaps validating the necessity for a plethora of depigmentation procedures in - vogue . by the 12 month ; color match was better , as the grafted site showed almost complete pigmentation . as a result , the periodontist 's score at the end of one year was significantly higher than at the end of 3 month . another interesting finding was that perception of the colour match did not strictly correlate with the degree of root coverage obtained , when the patients used the vas . conversely , the 9 sites that showed full coverage were scored higher by the periodontist . the connective tissue has been known to influence epithelial behaviors through the secretion of paracrine growth factors such as as keratinocyte growth factor ( kgf ) , direct contact and by communication through the basement membrane . further , superficial connective tissue has been shown to have a greater influence on the epithelium when compared to the deep connective tissue . although melanization is principally an epithelium related event ; factors such as fibroblast growth factor ( fgf ) has been shown to influence melanin formation . the acellular graft used in this study might have inhibited the effect of the underlying connective tissue due to the lack of cells necessary for the formation of the growth factors . we hypothesize that this is probably the reason for the slow melanin formation in the grafted site . as no histological examination could be made , a closer observation of the dynamics of melanization in alloderm grafted sites was not possible . connective tissue graft is gold standard for treatment of gingival recession but the disadvantages are the second surgical site and inadequate graft availability . hence acellular dermal matrix graft ( alloderm ) is the most successful and predictable procedure in the management of gingival recession due to adequate root coverage and good colour match , without the need for second surgical site .

background : predictable root coverage and good colour match are the major therapeutic end points in the treatment of gingival recession . alloderm has been used as a substitute to connective tissue graft , but its colour match in populations with a high degree of melanin pigmentation has not been extensively studied . the aim of this study was to evaluate the effectiveness of an acellular dermal matrix graft for root coverage procedures and to objectively analyze the post - operative esthetics using a visual analog scale ( vas).materials and methods : both male and female patients were selected , aged 20 - 50 years presenting with aesthetic problems due to the exposure of recession defects when smiling . a total of 14 patients contributed to 15 sites , each site falling into miller 's class i or class ii gingival recession.results:a total of 15 sites were treated and a mean coverage of ( 85.5621.70 and 83.3321.82% ) was obtained at the end of 3rd and 12th month respectively . a mean vas score of 7.931.03 and 8.130.99 ( 3rd and 12th month ) and 5.730.70 and 6.870.83 ( 3rd and 12th month ) was obtained when the colour match recorded by the patients and an independent observer , respectively.conclusion:the study showed that acellular dermal matrix graft ( alloderm ) may be successfully used to treat gingival recession , as adequate root coverage may be predictably obtained . the grafted areas underwent melanization from the 6th month onwards and complete blending with the adjacent sites was obtained at 1 year .

one major concern of endodontists is to prevent microleakage after root canal filling , in order to prevent bacterial invasion to the root canal space . that is because microorganisms play a significant role in pulpal and periapical diseases [ 1 , 2 ] . reported that in coronally unsealed endodontically treated teeth , saliva penetration was seen after 30 days regardless of the obturation technique ( lateral versus vertical condensation ) . trope et al . explained that endotoxins could penetrate through an obturated root canal in less than 21 days , if the coronal seal is not achieved . for the first time , bowman used gutta - percha as a root filling material and mentioned that one of the practical ways to limit microorganisms in the root canal system is to achieve a three dimensional root canal filling . this method can deprive the remaining microorganisms after cleaning and shaping of the canal system . the most popular material for root canal filling is the beta phase of gutta - percha . it is stated that guttapercha in alpha phase has special characteristics such as less shrinkage , lower viscosity and more adherence than the beta phase [ 57 ] . controversy exists regarding which phase of gutta - percha can provide a better apical seal . compared the radiographic quality of obturation with alpha and beta phases of gutta - percha ( thermafil versus lateral condensation method ) . they reported that the quality of the alpha phase of gutta - percha was significantly better . reported that more gutta - percha was seen in the lateral canals when alpha phase gutta - percha coated rigid carrier technique was used ; whereas more sealer was present when using cold lateral condensation and these differences were statistically significant . pommel and campes revealed that after one month , microbial leakage in thermafil method and vertical condensation technique was significantly less than that in lateral condensation and single cone methods . on the other hand , de deus et al . showed that there was no statistically significant difference in the sealing ability of lateral condensation , warm vertical condensation and thermafil methods in a period of 100 days . . showed that there was no statistically significant difference between thermafil and lateral condensation when evaluating dye microleakage after 24 hours , seven days and five months . compared the apical seal of lateral condensation , thermafil and one step technique by assessing microbial leakage . it should be noted that in all previous studies , the alpha phase of gutta - percha was used by the thermafil method [ 913 ] but the aim of this study was to compare the apical sealing ability of alpha and beta gutta - percha cones by using warm vertical condensation method . in this experimental study , 50 extracted human premolars with a single root canal were selected . the teeth , which had been previously treated endodontically , had more than one root canal , caries , calcification , fracture , internal or external root resorption , curvature and open apex were excluded from the study . access cavity was prepared in all samples . a # 15 k - file ( dentsply maillefer , ballaigues , switzerland ) was used to measure the canal 's diameter ( if # 15 k - file was loose , the tooth was excluded from the study ) . all samples were prepared with mtwo rotary files ( vdw , munich , germany ) up to # 35.04 . then , the canals were dried with paper points ( meta bio - med co. ltd . , the teeth were divided into three groups , according to the obturation technique used : 1- obturation with alpha phase gutta - percha ( vdw , munich , germany ) ( n=20).2- obturation with beta phase gutta - percha ( vdw , munich , germany ) ( n=20).3- control groups with no obturation . 1- obturation with alpha phase gutta - percha ( vdw , munich , germany ) ( n=20 ) . 2- obturation with beta phase gutta - percha ( vdw , munich , germany ) ( n=20 ) . a # 35.04 gutta - percha master cone and ah26 sealer were used by means of beefill pack ii ( vdw , munich , germany ) . after obturation , gutta - percha was cut with a # 30 plagger ( dentsply maillefer , ballaigues , switzerland ) and compressed . all samples were cut 10 mm coronal to the apex with a diamond disc ( d+z , bern , switzerland ) . the outer surfaces of the samples other than the apical 2 mm were covered with two layers of nail varnish for prevention of bacterial leakage from the accessory and lateral canals except for the apical foramen . samples were mounted and fixed in the plastic vial caps and sealed with cyanoacrylate glue ; then , they were sterilized with ethylene oxide gas for 24 hours . afterwards , mueller hinton broth ( merck , darmstadt , germany ) was added to the vials in such a way that the apical 2 mm of the roots was in contact with the medium . all obturated samples were exposed to the bacterial suspension of e. faecalis every three days coronally . samples in the control group were considered as negative controls ( n=2 ) and were not exposed to bacterial suspension ; the remaining control samples ( n=8 ) served as positive controls and were exposed to the bacterial suspension . the number of days required for the contamination of the entire root canals was recorded . the outer surfaces of the samples other than the apical 2 mm were covered with two layers of nail varnish for prevention of bacterial leakage from the accessory and lateral canals except for the apical foramen . samples were mounted and fixed in the plastic vial caps and sealed with cyanoacrylate glue ; then , they were sterilized with ethylene oxide gas for 24 hours . afterwards , mueller hinton broth ( merck , darmstadt , germany ) was added to the vials in such a way that the apical 2 mm of the roots was in contact with the medium . all obturated samples were exposed to the bacterial suspension of e. faecalis every three days coronally . samples in the control group were considered as negative controls ( n=2 ) and were not exposed to bacterial suspension ; the remaining control samples ( n=8 ) served as positive controls and were exposed to the bacterial suspension . the number of days required for the contamination of the entire root canals was recorded . distribution of bacterial leakage time ( by days ) in alpha and beta phase gutta - percha the negative control samples ( without bacteria and no canal filling ) showed no turbidity after 24 hours of incubation . the positive control samples ( with bacteria and no canal filling ) showed 100% turbidity after 24 hours . all samples in groups g1 and g2 were infected with e. faecalis after 30 days . the mean time of bacterial leakage in g1 and g2 was 12.059.85 and 10.57.8 days , respectively . the difference between the two groups was not statistically significant in this respect ( p=0.74 ) . the proper obturation of the root canal system is a key factor to achieve successful results in endodontic treatments . although beta phase guttapercha is the most commonly used obturation material , the alpha phase gutta - percha can flow better in the root canals and fill more lateral canals ; thus , it can provide a better apical seal . in this in vitro study , we used bacterial leakage model that is more similar to clinical situation than other microleakage evaluation methods . dye penetration is not a proper method to simulate the clinical setting . since e. faecalis is responsible for one - third of endodontic treatment failures , in the present study , we used e. faecalis suspension [ 1619 ] . used dye penetration method to assess the microleakage and they described that sealing ability of ah26 was better than that of tubliseal , sealapex and apexit . zhang et al . reported that alpha phase gutta - percha with warm vertical compaction technique moved significantly more into the lateral canals and depressions than the beta - phase gutta - percha . they showed that beta phase guttapercha had more shrinkage and led to higher level of microleakage . in this study , we did not observe any turbidity in muller hinton broth medium in the negative control group , which means nail varnish and cyanoacrylate glue prevent bacterial leakage from other parts of the root , except for the apical foramen . also , we observed complete turbidity in the positive control group . results of the current study showed that there was no statistically significant difference in apical bacterial leakage between alpha and beta phases of gutta - percha . in this in vitro study , we concluded that the type of gutta - percha crystallization had no impact on its apical sealing ability .

objectives : the aim of this study was to compare apical sealing ability of alpha and beta phases of gutta - percha by means of bacterial leakage model.materials and methods : fifty single - rooted human premolars were selected . the root canals were prepared with mtwo rotary instruments up to apical # 35.04 . forty teeth were randomly divided into two groups ( n= 20 ) . the root canals were obturated by alpha phase ( g1 ) and beta phase ( g2 ) of gutta - percha and ah26 sealer , respectively , with warm vertical compaction technique . ten teeth served as positive ( n=8 ) and negative ( n=2 ) control groups . then , the specimens were sterilized with ethylene oxide gas . bacterial suspension of enterococcus faecalis ( e. faecalis ) in 0.5 mcfarland concentration was prepared . all teeth were mounted in plastic vial caps containing muller hinton broth and then exposed to bacterial suspension of e. faecalis every three days up to 31 days . the number of days required for the contamination of the entire root canals was recorded . the data were analyzed using mann whitney u test.results:there were no significant differences in bacterial leakage between the g1 and g2 groups ( p>0.05 ) . negative controls revealed no microbial leakage ; whereas positive controls showed gross microbial leakage.conclusion:despite better thermal conduction and adaptability of alpha phase of guttapercha , our study revealed no significant difference in bacterial leakage between alpha and beta phases of gutta - percha in warm vertical compaction .

SECTION 1. SHORT TITLE. This Act may be cited as the ``Student Loan Repayment Assistance Act of 2015''. SEC. 2. EXCLUSION FROM GROSS INCOME OF BENEFITS UNDER CERTAIN STUDENT LOAN PAYMENT ASSISTANCE PROGRAMS. (a) In General.--Part III of subchapter B of chapter 1 of the Internal Revenue Code of 1986 is amended by inserting after section 127 the following new section: ``SEC. 127A. STUDENT LOAN PAYMENT ASSISTANCE PROGRAMS. ``(a) In General.--Gross income of a qualified employee does not include amounts paid or incurred by the employer for student loan payment assistance provided to such employee if the assistance is furnished pursuant to a program which is described in subsection (c). ``(b) Qualified Employee.--For purposes of this subsection, the term `qualified employee' means any employee who contributes (in addition to any amount excluded from gross income under this section) not less than $50 per month for payment of principal and interest on the loans subject to the student loan payment assistance program. ``(c) Limitations.-- ``(1) Assistance limitation.--The amount taken into account under subsection (a) with respect to an individual for student loan assistance with respect to student loan payments during a taxable year shall not exceed $6,000. ``(2) Earned income limitation.--The amount excluded from the income of an employee under subsection (a) for any taxable year shall not exceed the earned income of such employee for such taxable year. ``(d) Student Loan Payment Assistance Program.-- ``(1) In general.--For purposes of this section a student loan payment assistance program is a separate written plan of an employer for the exclusive benefit of his employees to provide such employees with student loan payment assistance which meets the requirements of paragraphs (2) through (10) of this subsection. If any plan would qualify as a student loan payment assistance program but for a failure to meet the requirements of this subsection, then, notwithstanding such failure, such plan shall be treated as a student loan payment assistance program in the case of employees who are not highly compensated employees. ``(2) Discrimination.--The contributions or benefits provided under the plan shall not discriminate in favor of employees who are highly compensated employees (within the meaning of section 414(q)). ``(3) Eligibility.--The program shall benefit employees who qualify under a classification set up by the employer and found by the Secretary not to be discriminatory in favor of employees described in paragraph (2). ``(4) Principal shareholders or owners.--Not more than 25 percent of the amounts paid or incurred by the employer for student loan payment assistance during the year may be provided for the class of individuals who are shareholders or owners (or their spouses or dependents), each of whom (on any day of the year) owns more than 5 percent of the stock or of the capital or profits interest in the employer. ``(5) No funding required.--A program referred to in paragraph (1) is not required to be funded. ``(6) Notification of eligible employees.--Reasonable notification of the availability and terms of the program shall be provided to eligible employees. ``(7) Statement of expenses.--The plan shall furnish to an employee, on or before January 31, a written statement showing the amounts paid or expenses incurred by the employer in providing student loan payment assistance to such employee during the previous calendar year. ``(8) Benefits.-- ``(A) In general.--A plan meets the requirements of this paragraph if the average benefits provided to employees who are not highly compensated employees under all plans of the employer is at least 55 percent of the average benefits provided to highly compensated employees under all plans of the employer. ``(B) Salary reduction agreements.--For purposes of subparagraph (A), in the case of any benefits provided through a salary reduction agreement, a plan may disregard any employees whose compensation is less than $25,000. For purposes of this subparagraph, the term `compensation' has the meaning given such term by section 414(q)(4), except that, under rules prescribed by the Secretary, an employer may elect to determine compensation on any other basis which does not discriminate in favor of highly compensated employees. ``(9) Contributions made directly to lender.--A plan meets the requirements of this paragraph if all benefits provided under the plan are paid directly to the holder of the indebtedness referred to in subsection (d)(1)(A)(i). ``(10) Matching contributions.--A plan which meets the requirements of paragraphs (2) through (9) shall not fail to be treated as a program described in this subsection merely because such plan provides for the employer to make matching contributions with respect to employee contributions. ``(e) Definitions and Special Rules.--For purposes of this section-- ``(1) Student loan payment assistance.-- ``(A) In general.--The term `student loan payment assistance' means the payment of principal or interest on-- ``(i) any indebtedness incurred by the employee solely to pay qualified higher education expenses (as defined in section 221) which-- ``(I) are paid or incurred within a reasonable period of time before or after the indebtedness was incurred, and ``(II) are attributable to education furnished during a period during which the employee was an eligible student, or ``(ii) any indebtedness used to refinance indebtedness described in clause (i). Such term shall not include any payment of principal or interest on indebtedness owed to a person who is related (within the meaning of section 267(b) or 707(b)(1)) to the taxpayer or to any person by reason of a loan under any qualified employer plan (as defined in section 72(p)(4)) or under any contract referred to in section 72(p)(5). ``(B) Eligible student.--For purposes of this subsection, the term `eligible student' means, with respect to any academic period, a student who meets the requirements of section 484(a)(1) of the Higher Education Act of 1965 (20 U.S.C. 1091(a)(1)), as in effect on the date of the enactment of this section. ``(C) Dependent.--The term `dependent' has the meaning given such term by section 152 (determined without regard to subsections (b)(1), (b)(2), and (d)(1)(B) thereof). ``(2) Earned income.--The term `earned income' shall have the meaning given such term in section 32(c)(2), but such term shall not include any amounts paid or incurred by an employer for student loan payment assistance to an employee. ``(3) Employee.--The term `employee' includes, for any year, an individual who is an employee within the meaning of section 401(c)(1) (relating to self-employed individuals). ``(4) Employer.--An individual who owns the entire interest in an unincorporated trade or business shall be treated as his own employer. A partnership shall be treated as the employer of each partner who is an employee within the meaning of paragraph (3). ``(5) Attribution rules.-- ``(A) Ownership of stock.--Ownership of stock in a corporation shall be determined in accordance with the rules provided under subsections (d) and (e) of section 1563 (without regard to section 1563(e)(3)(C)). ``(B) Interest in unincorporated trade or business.--The interest of an employee in a trade or business which is not incorporated shall be determined in accordance with regulations prescribed by the Secretary, which shall be based on principles similar to the principles which apply in the case of subparagraph (A). ``(6) Utilization test not applicable.--A student loan payment assistance program shall not be held or considered to fail to meet any requirements of subsection (c) (other than paragraphs (4) and (8) thereof) merely because of utilization rates for the different types of assistance made available under the program. ``(7) Disallowance of excluded amounts as credit or deduction.--No deduction or credit shall be allowed to the employee under any other section of this chapter for any amount excluded from the gross income of the employee by reason of this section. ``(8) Treatment of salary reduction amounts.--Any matching contribution withheld from an employee under a student loan payment assistance program pursuant to a salary reduction agreement shall be treated for purposes of this title as an amount paid by the employee and not as an amount paid by the employer.''. (b) Conforming Amendments.--Sections 221(d)(2)(A), 414(n)(3)(C) and (t)(2), 3121(a)(18), 3306(b)(13), 3401(a)(18), and 6039D(d)(1) of such Code are each amended by inserting ``127A,'' after ``127,''. (c) Clerical Amendment.--The table of sections for part III of subchapter B of chapter 1 of such Code is amended by inserting after the item relating to section 127 the following new item: ``Sec. 127A. Student loan payment assistance programs.''. (d) Effective Date.--The amendments made by this section shall apply to taxable years beginning after the date of the enactment of this Act. SEC. 3. DEDUCTION FOR STUDENT LOAN PAYMENTS WHICH ARE MATCHED BY AN EMPLOYER. (a) In General.--Part VII of subchapter B of chapter 1 of the Internal Revenue Code of 1986 is amended by redesignating section 224 as section 225 and by inserting after section 223 the following new section: ``SEC. 224. DEDUCTION FOR STUDENT LOAN PAYMENTS WHICH ARE MATCHED BY AN EMPLOYER. ``(a) In General.--In the case of an individual who is a qualified employee (as defined in section 127A), there shall be allowed as a deduction an amount equal to the student loan payments made by such individual with respect to which an employer of such individual makes matching contributions under a student loan payment assistance program which are excludible from the gross income of such employee under section 127A. ``(b) Annual Limitation.--The amount allowable as a deduction under subsection (a) with respect to any individual for any taxable year shall not exceed $6,000. ``(c) Lifetime Limitation.--The amount allowable as a deduction under subsection (a) with respect to any individual for any taxable year shall not exceed the excess of-- ``(1) $50,000, over ``(2) the aggregate amount allowable as a deduction under subsection (a) with respect to such individual for all prior taxable years. ``(d) Denial of Double Benefit.--Any amount excluded from the gross income of an individual under section 127A shall not be treated as an amount paid by such individual for purposes of this section. The amount of principal and interest with respect to which a deduction is allowed under this section shall not be taken into account in determining the amount of any other deduction or credit allowed under this chapter.''. (b) Clerical Amendment.--The table of sections for part VII of subchapter B of chapter 1 of such Code is amended by redesignating the item relating to section 224 as an item relating to section 225 and by inserting after the item relating to section 223 the following new item: ``Sec. 224. Deduction for student loan payments which are matched by an employer.''. (c) Effective Date.--The amendments made by this section shall apply to taxable years beginning after the date of the enactment of this Act.

Student Loan Repayment Assistance Act of 2015 Amends the Internal Revenue Code to exclude from the gross income of an employee amounts paid by an employer under a student loan payment assistance program. Requires participating employees to pay at least $50 per month on their student loans (in addition to the amount excluded from their gross income under such program). Limits the amount of such exclusion to $6,000 in a taxable year. Requires an employer student loan payment assistance program to be a separate written plan of an employer to provide employees with student loan payment assistance. Defines &quot;student loan payment assistance&quot; as the payment of principal or interest on any indebtedness incurred by an employee solely to pay qualified higher education expenses that are paid or incurred within a reasonable time before or after such indebtedness was incurred and that are attributable to education furnished during a period in which such employee was a student eligible for federal financial assistance. Allows an employee to take an income tax deduction in an amount equal to the employee's student loan payments that are matched by excludible employer contributions under a student loan payment assistance program. Limits the amount of such deduction to $6,000 in a taxable year and $50,000 over a lifetime.

SECTION 1. SHORT TITLE. This Act may be cited as the ``First-Time Homebuyer Savings Account Act of 2016''. SEC. 2. FIRST-TIME HOMEBUYER ACCOUNT. (a) In General.--Part VIII of subchapter F of chapter 1 of the Internal Revenue Code of 1986 is amended by adding at the end the following new section: ``SEC. 530A. FIRST-TIME HOMEBUYER ACCOUNT. ``(a) In General.--A first-time homebuyer account shall be exempt from taxation under this subtitle. Notwithstanding the preceding sentence, the first-time homebuyer account shall be subject to the taxes imposed by section 511 (relating to imposition of tax on unrelated business income of charitable organizations). ``(b) First-Time Homebuyer Account.--The term `first-time homebuyer account' means a trust created or organized in the United States exclusively for the purpose of paying the qualified principal residence purchase expenditures of an individual who is the designated beneficiary of the trust (and designated as a first-time homebuyer account at the time created or organized), but only if the written governing instrument creating the trust meets the following requirements: ``(1) No contribution will be accepted-- ``(A) unless it is in cash, ``(B) except in the case of a rollover contribution, if such contribution would result in aggregate contributions-- ``(i) for the taxable year exceeding $14,000 (200 percent of such amount in effect for the taxable year in the case of individuals who are married, own a first-time homebuyer account jointly, and file a joint return for the taxable year), ``(ii) for all taxable years exceeding $50,000, and ``(C) if the fair market value of the account to exceeds, or to the extent such contribution would result in the fair market value of the account exceeding, $150,000. ``(2) The trustee is a bank (as defined in section 408(n)) or another person who demonstrates to the satisfaction of the Secretary that the manner in which that person will administer the trust will be consistent with the requirements of this section or who has so demonstrated with respect to any individual retirement plan. ``(3) No part of the trust assets will be invested in life insurance contracts. ``(4) The assets of the trust shall not be commingled with other property except in a common trust fund or common investment fund. ``(c) Qualified Principal Residence Purchase Expenditures.--For purposes of this section-- ``(1) In general.--The term `qualified principal residence purchase expenditures' means, with respect to a designated beneficiary who is a first-time homebuyer-- ``(A) any amount paid toward the purchase price of a principal residence of the beneficiary, ``(B) any amount required to be paid to settle the purchase of such residence, and ``(C) any amount required to be paid by the beneficiary to obtain acquisition indebtedness with respect to such residence. ``(2) Purchase price.--The term `purchase price' means the adjusted basis of the residence on the date such residence is purchased. ``(d) Tax Treatment.-- ``(1) Distributions.-- ``(A) In general.--If distributions from a first- time homebuyer account for the taxable year do not exceed the qualified principal residence purchase expenditures of the designated beneficiary for the taxable year, no amount shall be includible in gross income. ``(B) Distributions in excess of expenditures.--If such distributions exceed such expenditures for the taxable year, such distributions shall be includible in the gross income of the distributee in the manner as provided in section 72 (to the extent not excluded from gross income under any other provision of this chapter), reduced by an amount which bears the same ratio to the amount otherwise so includible as such expenses bear to such distributions. ``(C) Additional tax for distributions not used for first-time homebuyer purposes.-- ``(i) In general.--The tax imposed by this chapter for any taxable year on any taxpayer who receives a payment or distribution from a first-time homebuyer account which is includible in gross income shall be increased by the applicable percentage of the amount which is so includible. ``(ii) Applicable percentage.--For purposes of clause (i), the applicable percentage is-- ``(I) in the case of a payment or distribution made not later than 10 years after the date of the first contribution to the account, 5 percent, and ``(II) in the case of any other payment or distribution, 10 percent. ``(iii) Exceptions.--Clause (i) shall not apply if the payment or distributions-- ``(I) is made to a beneficiary (or to the estate of the designated beneficiary) on or after the death of the designated beneficiary, ``(II) is attributable to the designated beneficiary's being disabled (within the meaning of section 72(m)(7)), or ``(III) are made under rules similar to the rules under section 408(d)(4) (relating to contributions returned before due date of return). ``(D) Rollovers.--Subparagraph (A) shall not apply to any amount paid or distributed from a first-time homebuyer account to the extent that the amount received is paid, not later than the 60th day after the date of such payment or distribution, into another first-time homebuyer account for the benefit of the same beneficiary. The preceding sentence shall not apply to any payment or distribution if it applied to any prior payment or distribution during the 12-month period ending on the date of the payment or distribution. ``(E) Change in beneficiary.--Any change in the beneficiary of a first-time homebuyer account shall not be treated as a distribution for purposes of subparagraph (A). ``(F) Disallowance of excluded amounts as deduction, credit, or exclusion.--No deduction, credit, or exclusion shall be allowed to the taxpayer under any other section for any qualified principal residence purchase expenditures to the extent taken into account in determining the amount of the exclusion under this paragraph. ``(2) Estate and gift tax with respect to the account.-- Rules similar to the rules of paragraphs (2), (4), and (5) of section 529(c) shall apply for purposes of this section. ``(3) Tax treatment after death of account holder.-- ``(A) Jointly held accounts.--In the case of a first-time homebuyer account which was jointly held by spouses, if the surviving spouse acquires the deceased spouse's interest in a first-time homebuyer account by reason of being the designated beneficiary of such account at the death, such account shall be treated as if the spouse were the sole account holder. ``(B) Other cases.-- ``(i) In general.--If, by reason of the death of the account holder, any person acquires the account holder's interest in an first-time homebuyer account in a case to which subparagraph (A) does not apply-- ``(I) such account shall cease to be a first-time homebuyer account as of the date of death, and ``(II) an amount equal to the fair market value of the assets in such account on such date shall be includible if such person is not the estate of such holder, in such person's gross income for the taxable year which includes such date, or if such person is the estate of such holder, in such holder's gross income for the last taxable year of such holder. ``(ii) Deduction for estate taxes.--An appropriate deduction shall be allowed under section 691(c) to any person (other than the decedent or the decedent's spouse) with respect to amounts included in gross income under clause (i). ``(e) Other Definitions and Special Rules.--For purposes of this section-- ``(1) First-time homebuyer.-- ``(A) In general.--The term `first-time homebuyer' means any individual if such individual (and if married, such individual's spouse) has had no present ownership interest in a principal residence. ``(B) Special rule for divorced individuals.--Any individual who is divorced and is not described in subparagraph (A) shall be treated as a first-time homebuyer for purposes of this section if such individual had no present ownership interest in a principal residence since such individual's most recent divorce and during the 3-year period ending on the date of the purchase of the principal residence with respect to which payments from a first-time homebuyer account are made under this section. ``(2) Principal residence.--The term `principal residence' has the same meaning as when used in section 121. ``(3) Designated beneficiary.--The term `designated beneficiary' means-- ``(A) the individual designated at the commencement of the first-time homebuyer account as the beneficiary of amounts paid (or to be paid) to the account, or ``(B) in the case of a change in beneficiaries described in subsection (d)(1)(C), the individual who is the new beneficiary ``(4) Account ownership.--Except in the case of individuals who are married, an account may be owned by only one individual and may only have one designated beneficiary. ``(5) Cost-of-living adjustment.--In the case of any taxable year beginning in a calendar year after 2017, the dollar amounts under subsection (b)(1) 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 the calendar year in which the taxable year begins, determined by substituting `calendar year 2007' for `calendar year 1992' in subparagraph (B) thereof. If any amount after adjustment under the preceding sentence is not a multiple of $100, such amount shall be rounded to the next lower multiple of $100.''. (b) Excess Contributions.-- (1) In general.--Section 4973(a) of such Code is amended by striking ``or'' at the end of paragraph (5), by inserting ``or'' at the end of paragraph (6), and by inserting after paragraph (6) the following new paragraph: ``(7) a first-time homebuyer account (within the meaning of section 530A),''. (2) Excess contributions.--Section 4973 of such Code is amended by adding at the end the following new subsection: ``(i) Excess Contributions to First-Time Homebuyer Account.--In the case of a first-time homebuyer account, the term `excess contributions' means the amount by which the amount contributed for the taxable year to such account (other than contributions described in section 530A(d)(1)(C) (iv) and (v)) exceeds the contribution limits under section 530A(b). For purposes of the preceding sentence, any contribution which is distributed from the account in a distribution to which section 530A(d)(1)(C)(iii)(III) applies shall be treated as an amount not contributed.''. (c) Clerical Amendment.--The table of sections for part VIII of subchapter F of chapter 1 of such Code is amended by adding at the end the following new item: ``Sec. 530A. First-time homebuyer account.''. (d) Effective Date.--The amendments made by this section shall apply to taxable years beginning after the date of the enactment of this Act.

First-Time Homebuyer Savings Account Act of 2016 This bill amends the Internal Revenue Code to provide for tax-preferred savings accounts for first-time homebuyers. An individual may make up to $14,000 per year in after-tax contributions to the account, subject to a $50,000 lifetime contribution limit, a $150,000 limit on the fair market value of the account, and adjustments for inflation after 2017. Distributions from the account that are used to pay the qualified principal residence purchase expenditures of the designated beneficiary are excluded from gross income. A &quot;qualified principal residence purchase expenditure&quot; is, with respect to a designated beneficiary who is a first-time homebuyer, any amount: (1) paid toward the purchase price of a principal residence of the beneficiary, (2) required to be paid to settle the purchase of such residence, or (3) required to be paid by the beneficiary to obtain acquisition indebtedness with respect to the residence. Excess contributions to the account, distributions that exceed the qualified principal residence purchase expenditures of the beneficiary, and distributions that are not used for first-time homebuyer purposes are subject to specified taxes.

let @xmath2 be a smooth , primitively polarized complex @xmath0 surface of genus @xmath15 , with @xmath16 a globally generated , indivisible line bundle with @xmath17 . we denote by @xmath1 the moduli space ( or stack ) of smooth primitively polarized @xmath0 surfaces of genus @xmath13 , which is smooth , irreducible , of dimension @xmath18 . its elements correspond to the isomorphism classes @xmath19 $ ] of pairs @xmath2 as above . we will often abuse notation and denote @xmath19 $ ] simply by @xmath20 . for @xmath21 , the arithmetic genus of the curves in @xmath6 is @xmath22 . let @xmath5 be an integer such that @xmath23 . we consider the quasi projective scheme ( or stack ) @xmath24 ( or simply @xmath25 , when @xmath13 is understood ) , called the @xmath26_universal severi variety _ , parametrizing all pairs @xmath27 , with @xmath28 and @xmath29 a reduced and irreducible curve , with only @xmath5 nodes as singularities . one has the projection @xmath30 whose fiber over @xmath31 is the variety , denoted by @xmath32 , called the _ severi variety _ of @xmath5-nodal irreducible curves in @xmath6 . the variety @xmath33 is well - known to be smooth , pure of dimension @xmath34 . we will often write @xmath35 for @xmath36 if no confusion arises : this is the _ geometric genus _ of any curve in @xmath25 . one has the obvious _ moduli map _ @xmath37 & \m_g,}\]]where @xmath38 is moduli space of smooth genus@xmath35 curves , sending a curve @xmath39 to the class of its normalization . our objective in this paper is to find conditions on @xmath13 , @xmath40 and @xmath5 ( or equivalently @xmath35 ) ensuring the existence of a component @xmath9 of @xmath41 , such that @xmath42 is either [ ( a ) ] _ generically finite _ onto its image , or _ dominant _ onto @xmath43 . note that ( a ) can happen only for @xmath44 and ( b ) only for @xmath45 . we collect our results in the following statement , which , for any @xmath13 , solves the problem for all but finitely many @xmath46 ; for instance , for @xmath47 and @xmath48 the result yields that the moduli map has maximal rank on some component for any @xmath35 . [ thm : main ] with the above notation , one has : @xmath49 for the following values of @xmath50 , @xmath40 and @xmath35 there is an irreducible component @xmath9 of @xmath25 , such that the moduli map @xmath51 is dominant : * @xmath52 and @xmath53 ; * @xmath54 , @xmath55 and @xmath56 ; * @xmath57 , @xmath58 and @xmath59 ; * @xmath60 , @xmath61 and @xmath62 ; * @xmath47 , @xmath63 and @xmath64 . @xmath65 for the following values of @xmath13 , @xmath40 and @xmath35 there is an irreducible component @xmath9 of @xmath25 , such that the moduli map @xmath66 is generically finite onto its and @xmath67 ; * @xmath68 , @xmath69 and @xmath70 ; * @xmath14 , @xmath48 and @xmath71 . to prove this , it suffices to exhibit some specific curve in the universal severi variety such that a component of the fiber of the moduli map at that curve has the _ right dimension _ , i.e , @xmath72 . to do this , we argue by degeneration , i.e. , we consider partial compactifications @xmath73 and @xmath74 of both @xmath1 and @xmath25 and prove the above assertion for curves in the boundary . the partial compactification @xmath73 is obtained by adding to @xmath1 a divisor @xmath75 parametrizing pairs @xmath76 , where @xmath20 is a _ reducible @xmath0 surface _ of genus @xmath13 that can be realised in @xmath77 as the union of two rational normal scrolls intersecting along an elliptic normal curve @xmath78 , and @xmath79 is the zero scheme of a section of the first cotangent sheaf @xmath80 , consisting of @xmath81 points on @xmath78 . these @xmath81 points , plus a subtle deformation argument of nodal curves , play a fundamental role in our approach for @xmath52 . for @xmath82 we specialize curves in the severi variety to suitable unions of curves used for @xmath52 plus other types of limit curves , namely tacnodal limit curves passing through two of the @xmath81 special points . the paper is organized as follows . the short [ s : setup ] is devoted to preliminary results , and we in particular define a slightly broader notion of severi variety including the cases of curves with more than @xmath5 nodes and of reducible curves . in [ s : stablek3 ] we introduce the partial compactification @xmath73 we use ( cf.@xcite ) . in [ sec : limnod1 ] we start the analysis of the case @xmath52 , and we introduce the curves in @xmath83 over the reducible surfaces in @xmath75 that we use for proving our results . section [ sec : modulimap ] is devoted to the study of the fiber of the moduli map for the curves introduced in the previous [ sec : limnod1 ] : this is the technical core of this paper . in [ sec : m1 ] we prove the @xmath52 part of theorem [ thm : main ] . in [ sec : limnod ] we introduce the tacnodal limit curves mentioned above , which are needed to work out the cases @xmath82 of theorem [ thm : main ] in [ sec : dominance][sec : genfin ] . the study of severi varieties is classical and closely related to modular properties . for the case of nodal plane curves the traditional reference is severi s wide exposition in , although already in enriques chisini s famous book families of plane nodal curves with general moduli have been considered . the most important result on this subject is harris proof in @xcite of the so called _ severi conjecture _ , which asserts that the severi variety of irreducible plane curves of degree @xmath84 with @xmath5 nodes is irreducible . in recent times there has been a growing interest in severi varieties for @xmath0 surfaces and their modular properties . in their seminal works @xcite mori and mukai proved that in the case of smooth curves in the hyperplane section class , i.e. , what we denoted here by @xmath85 , the modular map : dominates @xmath86 , for @xmath87 and @xmath88 , whereas this is false for @xmath89 , and is generically finite between @xmath85 and its image in @xmath86 for @xmath88 and @xmath90 , whereas this is false for @xmath91 . in @xcite one gives a different proof of these results , proving , in addition , that @xmath85 birationally maps to its image in @xmath86 for @xmath88 and @xmath90 . the case of @xmath92 , with @xmath82 , has been studied in @xcite . as for @xmath93 , in @xcite one proves that @xmath94 dominates @xmath38 for @xmath95 . quite recently , kemeny , inspired by ideas of mukai s , and using geometric constructions of appropriate curves on @xmath0 surfaces with high rank picard group , proved in @xcite that there is an irreducible component of @xmath10 for which the moduli map is generically finite onto its image for all but finitely many values of @xmath13 , @xmath40 and @xmath5 . kemeny s results partly intersect with part @xmath65 of our theorem [ thm : main ] ; his results are slightly stronger than ours for @xmath96 , however our results are stronger and in fact optimal for @xmath14 ( if @xmath48 ) . moreover part @xmath49 , which is also optimal for @xmath14 ( except for some very low values of @xmath13 ) , is completely new . note that a different proof of the case @xmath52 in theorem [ thm : main ] has recently been given in @xcite . to finish , it is the case to mention that probably the most interesting open problems on the subject are the following : for @xmath97 general , is the severi variety @xmath98 irreducible ? is the universal severi variety @xmath10 irreducible ? so far it is only known that @xmath94 is irreducible for @xmath99 and @xmath100 ( see @xcite ) . we work over @xmath101 . for @xmath102 a gorenstein variety , we denote by @xmath103 and @xmath104 the structure sheaf and the canonical line bundle , respectively , and @xmath105 will denote a canonical divisor of @xmath102 . if @xmath106 , then @xmath107 denotes the zariski tangent space to @xmath102 at @xmath108 . for @xmath109 a subscheme , @xmath110 ( or simply @xmath111 if there is no danger of confusion ) will denote its ideal sheaf whereas @xmath112 its normal sheaf . for line bundles we will sometimes abuse notation and use the additive notation to denote tensor products . finally , we will denote by @xmath113 the inverse of a line bundle @xmath16 and by @xmath114 the linear equivalence of cartier divisors . the first three authors have been supported by the gnsaga of indam and by the prin project `` geometry of projective varieties '' , funded by the italian miur . the authors wish to thank m. kemeny for interesting and useful conversations on the subject of this paper . we also thank the referee for a very careful reading and for making several observations and suggestions that improved the readability of the paper , as well as discovering some inaccuracies in the first version . to prove our main results , we will need to consider nodal , _ reducible _ curves . to this end we will work with a slightly broader notion of _ severi variety _ than the one from the introduction . let @xmath115 be a base point free complete linear system on a smooth @xmath0 surface @xmath20 . consider the quasi - projective scheme @xmath116 parametrizing pairs @xmath117 such that + @xmath39 is a reduced ( possibly reducible ) nodal curve in @xmath115 ; + @xmath118 is a subset of @xmath5 of its nodes , henceforth called the _ marked nodes _ ( called _ assigned nodes _ in @xcite ) , such that the normalization @xmath119 at @xmath118 is @xmath120-connected . then , by ( * ? ? ? 3.8 and 3.11 ) , one has : + @xmath116 is smooth of codimension @xmath5 in @xmath115 ; + in any component of @xmath116 , the general pair @xmath117 is such that @xmath39 is irreducible with precisely @xmath5 nodes . we leave it to the reader to verify that the conditions in @xcite are in fact equivalent to ours . we call @xmath116 the _ severi variety _ of nodal curves in @xmath115 with @xmath5 marked nodes . this definition is different from others one finds in the literature ( and even from the one in the introduction ! ) . usually , in the severi variety one considers only irreducible curves @xmath39 with exactly @xmath5 nodes . with our definition we consider the desingularization of a partial compactification of the latter variety . this will be useful for our purposes . we define the @xmath26-universal severi variety @xmath10 ( or simply @xmath25 when @xmath13 is understood ) to be the quasi - projective variety ( or stack ) parametrizing triples @xmath121 , with @xmath122 and @xmath123 . it is smooth and pure of dimension @xmath124 and the general element in any component is a triple @xmath121 with @xmath39 irreducible with exactly @xmath5 nodes . we may simplify notation and identify @xmath125 with the curve @xmath39 , when the surface @xmath20 and the set of nodes @xmath118 are intended . one has the projection @xmath126 & \k_p}\ ] ] whose fiber over @xmath127 is the severi variety @xmath128 . similarly , we have a _ moduli map _ @xmath129 & \overline{{\rm m}}_{g}}\ ] ] ( where @xmath130 is the moduli space of genus @xmath35 stable curves and we recall that @xmath131 ) , which sends a curve @xmath39 to the stable model of the partial normalization of @xmath39 at the @xmath5 marked nodes . for @xmath97 and integers @xmath132 , one has a correspondence @xmath133 with the two projections @xmath134^{p_2 } \ar[ll]_{p_1 } & & v_{m,\delta'}(s ) , } \ ] ] which are both finite onto their images . precisely : + @xmath135 is surjective , tale of degree @xmath136 , hence @xmath137 ; + @xmath138 is birational onto its image , denoted by @xmath139}(s)$ ] , which is pure with @xmath140}(s))=g_{m,\delta'}=\dim(v_{m,\delta}(s))-(\delta'-\delta).\ ] ] roughly speaking , the variety @xmath139}(s)$ ] is the proper subvariety of @xmath33 consisting of curves with at least @xmath141 nodes , @xmath5 of them marked . the general point of any component of @xmath139}(s)$ ] corresponds to a curve with exactly @xmath141 nodes . so one has the filtration @xmath142}(s)\subset v_{[m,\delta , p(m)-1]}(s)\subset \ldots \subset v_{[m,\delta,\delta+1]}(s)\subset v_{[m,\delta,\delta]}(s ) = v_{m,\delta}(s)\ ] ] in which each variety has codimension @xmath143 in the subsequent . [ rem : filtr ] given a component @xmath144 of @xmath33 and @xmath145 , there is no a priori guarantee that @xmath146}(s)\neq \emptyset$ ] . if this is the case , then each component of @xmath146}(s)$ ] has codimension @xmath147 in @xmath144 and we say that @xmath144 is _ @xmath141complete_. if @xmath144 is @xmath141complete , then it is also @xmath148complete for @xmath149 . if @xmath144 is @xmath150complete we say it is _ fully complete _ , i.e. , @xmath144 is fully complete if and only if it contains a point parametrizing a rational nodal curve . if @xmath144 is a component of @xmath33 and @xmath151 a component of @xmath152 , such that @xmath153 , then @xmath154 dominates a component @xmath155 of @xmath139}$ ] contained in @xmath144 , whose general point is a curve in @xmath151 with @xmath5 marked nodes . in this case we will abuse language and say that @xmath151 is _ included _ in @xmath144 . of course one can make a relative version of the previous definitions , and make sense of the subscheme @xmath156}\subset \v_{m,\delta}$ ] , which has dimension @xmath157 , of the filtration @xmath158}\subset \v_{[m,\delta , p(m)-1]}\subset \ldots \subset \v_{[m,\delta,\delta+1]}\subset \v_{m,\delta},\ ] ] of the definition of a @xmath141complete component @xmath9 of @xmath25 , for @xmath145 , of fully complete components , etc . for @xmath145 , the image of @xmath156}$ ] via @xmath159 sits in the @xmath160codimensional locus @xmath161 of @xmath160 nodal curves in @xmath162 . in this section we consider some reducible surfaces ( see @xcite ) , which are _ limits _ of smooth , polarized @xmath0 surfaces , in the sense of the following : [ deformation ] let @xmath163 be a compact , connected analytic variety . a variety @xmath164 is said to be a deformation of @xmath163 if there exists a proper , flat morphism @xmath165 such that @xmath166 . accordingly , @xmath163 is said to be a flat limit of @xmath167 , for @xmath168 . if @xmath164 is smooth and if any of the @xmath169-fibers has at most normal crossing singularities , @xmath170 is said to be a semi - stable deformation of @xmath163 ( and @xmath163 is a semi - stable limit of @xmath171 , @xmath168 ) . if , in addition , @xmath171 is a smooth @xmath0 surface , for @xmath168 , then @xmath163 is a semi - stable limit of @xmath0 surfaces . if , in the above setting , one has a line bundle @xmath172 on @xmath164 , with @xmath173 for @xmath168 and @xmath174 , then one says that @xmath175 is a _ limit _ of @xmath176 for @xmath168 . let @xmath177 be an integer with @xmath178 and @xmath179 . if @xmath180 is an elliptic normal curve of degree @xmath181 , we set @xmath182 . consider two _ general _ line bundles @xmath183 with @xmath184 . we denote by @xmath185 the rational normal scroll of degree @xmath186 in @xmath187 described by the secant lines to @xmath188 spanned by the divisors in @xmath189 , for @xmath190 . we have @xmath191 the surfaces @xmath192 and @xmath193 are @xmath194bundles on @xmath194 . we denote by @xmath195 and @xmath196 a minimal section and a fiber of the ruling of @xmath197 , respectively , so that @xmath198 and @xmath199 , and @xmath200 by ( * ? ? ? * thm.1 ) , @xmath192 and @xmath193 intersect transversely along @xmath188 , which is anticanonical on @xmath185 , i.e. @xmath201 hence @xmath202 has normal crossings and @xmath203 is trivial . we set @xmath204 . the first cotangent sheaf @xmath205 ( cf . @xcite ) is the degree @xmath81 line bundle on @xmath188 @xmath206 the last isomorphism coming from and . the surface @xmath207 is a flat limit of smooth @xmath0 surfaces in @xmath187 . namely , if @xmath208 is the component of the hilbert scheme of surfaces in @xmath77 containing @xmath0 surfaces @xmath20 such that @xmath209\in \k_p$ ] , then @xmath207 sits in @xmath208 and , for general choices of @xmath210 , the hilbert scheme @xmath208 is smooth at @xmath207 ( see @xcite ) . however , the fact that @xmath205 is non - trivial implies that @xmath207 is not a semi stable limit of @xmath0 surfaces : indeed , the total space of every flat deformation of @xmath207 to @xmath0 surfaces in @xmath208 is singular along a divisor @xmath211 ( cf . * prop . 1.11 and 2 ) ) . more precisely ( see again @xcite for details ) , if @xmath212\,\ , \ar@{^{(}->}[r ] & \r'\ar[d]^ { \pi ' } \ar@{^{(}->}[r ] \ar[dr]^ { { \rm pr_2 } } & \mathbb d\times \pp^ p\ar[d ] \\\ 0\,\ , \ar@{^{(}->}[r ] & \mathbb d&\pp^ p } \ ] ] is a deformation of @xmath207 in @xmath213 whose general member is a smooth @xmath0 surface , then @xmath214 has double points at the points of a divisor @xmath215 associated to tangent direction to @xmath208 at @xmath207 determined by the deformation , via the standard map @xmath216 if @xmath79 is reduced ( this is the case if is general enough ) , then the tangent cone to @xmath214 at each of the 16 points of @xmath79 has rank 4 . in this case , by blowing up @xmath214 at the points of @xmath79 , the exceptional divisors are rank @xmath217 quadric surfaces and , by contracting each of them along a ruling on one of the two irreducible components of the strict transform of @xmath207 , one obtains a small resolution of singularities @xmath218 and a semi - stable degeneration @xmath219 of @xmath0 surfaces , with central fiber @xmath220 , where @xmath221 , for @xmath222 and still @xmath223 . note that we have a line bundle on @xmath224 , defined as @xmath225 . so @xmath219 is a deformation of polarized @xmath0 surfaces , and we set @xmath226 . we will abuse notation and terminology by identifying curves on @xmath207 with their proper transforms on @xmath163 ( so we may talk of _ lines _ on @xmath163 , etc . ) . we will set @xmath227 ; then @xmath228 ( and we will often identify them ) . we have @xmath229 . if the divisor @xmath79 corresponding to the deformation is not reduced , the situation can be handled in a similar way , but we will not dwell on it , because we will not need it . the above limits @xmath163 of @xmath0 surfaces are _ stable _ , type ii degenerations according to the kulikov - persson - pinkham classification of semi - stable degenerations of @xmath0 surfaces ( see @xcite ) . by ( 4.10 ) there is a normal , separated partial compactification @xmath230 of @xmath1 obtained by adding to @xmath1 a smooth divisor consisting of various components corresponding to the various kinds of type ii degenerations of @xmath0 surfaces . one of these components , which we henceforward call @xmath231 , corresponds to the degenerations we mentioned above . specifically , points of @xmath231 parametrize isomorphism classes of pairs @xmath232 with @xmath233 as above and @xmath234 , cf . since all our considerations will be local around general members of @xmath231 , where the associated @xmath79 is reduced , we may and will henceforth assume ( after substituting @xmath230 and @xmath231 with dense open subvarieties ) that @xmath230 is smooth , @xmath235 and that @xmath79 is reduced for all @xmath236 . thus , again since all our considerations will be local around such pairs , we may identify @xmath232 with the surface @xmath237 , as above , with @xmath238 and @xmath239 the blow up of @xmath193 at the @xmath81 points of @xmath79 on @xmath188 . if @xmath240 , we denote by @xmath241 the exceptional divisor on @xmath239 over @xmath242 , for @xmath243 , and we set @xmath244 . to be explicit , let us denote by @xmath245 the locally closed subscheme whose points correspond to unions of scrolls @xmath202 with @xmath246 general as above and such that @xmath236 for some @xmath234 . one has an obvious dominant morphism @xmath247 whose fiber over the class of the elliptic curve @xmath188 , modulo projectivities @xmath248 , is an open subset of @xmath249 modulo the action of @xmath250 . hence @xmath251 so that for @xmath252 general , the _ normal space _ @xmath253 has dimension 16 . the map factors through a map @xmath254 which is an isomorphism ( see @xcite ) . we denote by @xmath255 the @xmath248quotient of @xmath256 , which , by the above argument , has dimension @xmath257 . by definition , there is a surjective morphism @xmath258 whose fiber over ( the class of ) @xmath207 is a dense , open subset of @xmath259 , which has dimension @xmath260 ( by , given @xmath246 and @xmath261 , then @xmath262 is determined ) . this , by the way , confirms that @xmath263 . the universal severi variety @xmath25 has a partial compactification @xmath264 ( see ( * ? ? ? * lemma 1.4 ) ) , with a morphism @xmath265 extending @xmath266 , where the fiber @xmath267 over a general @xmath268 consists of all nodal curves @xmath269 , with @xmath5 marked , non disconnecting nodes in the smooth locus of @xmath163 , i.e. , the partial normalization of @xmath39 at the @xmath5 nodes is connected . ( there exist more refined partial compactifications of @xmath25 , for instance by adding curves with tacnodes along @xmath78 , as considered in @xcite , following @xcite ; we will consider such curves in [ sec : limnod ] , but we do not need them now ) . the total transform @xmath39 of a nodal curve @xmath270 with @xmath271 marked nodes in the smooth locus of @xmath207 and @xmath272 marked nodes at points of @xmath79 , with @xmath273 , lies in @xmath267 , since it contains the exceptional divisors on @xmath239 over the @xmath272 points of @xmath79 , and has a marked node on each of them off @xmath78 . as for the smooth case , @xmath267 , is smooth , of dimension @xmath274 . we can also consider @xmath147 codimensional subvarieties of @xmath267 of the form @xmath275}(r)$ ] , with @xmath276 , etc . finally , there is an _ extended moduli map _ we end this section with a definition , related to the construction of the surfaces @xmath207 , that we will need later . [ def : nonpiaceraaconcy ] let @xmath78 be a smooth elliptic curve with two degree - two line bundles @xmath278 and @xmath279 on it . for any integer @xmath280 , we define the automorphism @xmath281 on @xmath78 that sends @xmath282 to the unique point @xmath283 satisfying @xmath284 for any @xmath282 , we define the effective divisor @xmath285 to be the degree @xmath286 divisor @xmath287 given @xmath288 , with @xmath289 as explained in the previous section , we will now describe certain curves in @xmath290 lying on @xmath163 . [ def : compopartenza ] let @xmath291 be non negative integers such that @xmath292 . set @xmath293 and assume @xmath294 , where @xmath295 we define @xmath296 to be the set of reduced curves in @xmath297 : + [ ( a ) ] having exactly @xmath298 nodes on @xmath299 and @xmath300 nodes on @xmath301 , hence they split off @xmath302 lines on @xmath303 , for @xmath222 ; + such that the union of these @xmath304 lines is connected ; + containing exactly @xmath305 irreducible components of @xmath306 , so they have @xmath305 further nodes , none of them lying on @xmath78 . these curves have exactly @xmath5 nodes on the smooth locus of @xmath163 , which are the _ marked _ nodes . we write @xmath307 for @xmath308 . for any curve @xmath39 in @xmath296 , we denote by @xmath309 the connected union of @xmath84 lines as in ( b ) , called the _ line chain _ of @xmath39 , and by @xmath310 the irreducible component of the residual curve to @xmath309 and to the @xmath305 components of the exceptional curve @xmath306 on @xmath303 , for @xmath222 . curves in @xmath296 are total transforms of curves on @xmath311 with @xmath84 marked nodes on @xmath312 and passing through @xmath305 marked points in @xmath79 . members of @xmath307 are shown in the following pictures , which also show their images via the moduli map @xmath313 ( provided @xmath314 if @xmath5 is odd and @xmath315 if @xmath5 is even , otherwise the image in moduli is different ) . the curves @xmath316 , @xmath222 , are mapped each to one of the two rational components of the image curve in @xmath317 . the situation is similar for curves in @xmath296 , with @xmath318 . @xmath319{cfgk1.eps } & \includegraphics[width=8cm]{cfgk2.eps } \\ \end{array}\ ] ] the condition @xmath294 guarantees that the normalization of a curve in @xmath320 at the @xmath5 marked nodes is connected . the points @xmath321 and @xmath322 in the picture are called _ the distinguished points of the curve in @xmath296_. they satisfy the relation @xmath323 ( equivalently , @xmath324 if @xmath84 is odd ) . note that @xmath325 if @xmath5 is odd , whereas @xmath326 and @xmath327 if @xmath5 is even . we will consider the pair of distinguished points as an element @xmath328 when @xmath84 is odd , whereas we will consider the pair as an ordered element @xmath329 when @xmath84 is even , since we then can distinguish @xmath321 and @xmath322 , as @xmath330 and @xmath331 . recalling , we note that @xmath332 ( equivalently , @xmath333 if @xmath84 is odd ) is the ( reduced ) divisor of intersection points of the line chain of the curve in @xmath307 with @xmath78 . [ prop : rightdim ] assume @xmath334 . then @xmath307 is a smooth , dense open subset of a component of dimension @xmath335 of @xmath336 . if @xmath5 is even we denote by @xmath337 the graph of the translation by @xmath338 . then we have surjective morphisms @xmath339 take any point @xmath340 or @xmath341 in the target of @xmath342 . set @xmath343 , which is an effective divisor of degree @xmath344 on @xmath78 . then @xmath345 defines a unique line chain @xmath346 on @xmath163 and the fiber @xmath347 is a dense , open subset of the projective space @xmath348 . since @xmath349 then @xmath350 is irreducible of dimension @xmath351 . the smoothness of @xmath336 at the points of @xmath307 follows , as usual , because the @xmath5 marked nodes are non disconnecting ( cf . * rmk.1.1 ) ) . the same argument proves the following : [ prop : rightdim2 ] let @xmath352 be non negative integers such that @xmath353 . set @xmath293 and assume @xmath354 . then @xmath296 is a union of smooth , open dense subsets of components of dimension @xmath335 of @xmath336 . the number of components of @xmath296 is @xmath355 , depending on the choice of subdivisors of degree @xmath356 of @xmath79 . we can finally consider the universal family @xmath357 , irreducible by monodromy , parametrizing all pairs @xmath358 with @xmath359 and @xmath360 with the map @xmath361 , whose general fiber is smooth of dimension @xmath35 , so that @xmath362 . note that @xmath83 is smooth along @xmath357 . we will only be concerned with the cases @xmath363 , and mostly with @xmath364 . [ def : componente ] for @xmath354 , we denote by @xmath365 the unique irreducible component of @xmath83 containing @xmath366 if @xmath367 and @xmath368 if @xmath369 . we denote by @xmath370 the fiber of @xmath365 over @xmath127 . we denote by @xmath371 and @xmath372 the restrictions of @xmath373 and @xmath374 , respectively . [ rem : imp ] it is useful to notice that , for @xmath375 one has @xmath376and @xmath377 hence we also have @xmath378 i.e. , @xmath379 is fully complete ( see remark [ rem : filtr ] ) . it follows by monodromy that for general @xmath127 , every component of @xmath380 is fully complete . this section is devoted to the study of the dimension of the fibers of the moduli map @xmath381 over curves arising from reducible @xmath0 surfaces . for any @xmath382 , we define varieties of nodal curves analogously to definition [ def : compopartenza ] : we denote by @xmath383 the set of reduced curves in @xmath384 having exactly @xmath385 nodes on @xmath386 and @xmath387 nodes on @xmath388 , so that they split off a total of @xmath5 lines , and such that the union of these @xmath5 lines is connected . clearly , if @xmath311 for some @xmath389 , then there is a dominant , injective map @xmath390 & w_{\delta}(r ' ) } \ ] ] mapping a curve in @xmath307 to its isomorphic image on @xmath207 . the image of this map is precisely the set of curves in @xmath383 not passing through any of the points in @xmath79 . the concepts of _ line chain _ , _ distinguished pair of points _ and curves @xmath310 associated to an element of @xmath383 are defined in the same way as for the curves in @xmath307 . as above , we can consider the irreducible variety @xmath391 parametrizing all pairs @xmath392 with @xmath382 and @xmath393 and there is an obvious ( now surjective ! ) map @xmath394 . more generally , we may define a universal severi variety of nodal curves with @xmath5 marked nodes on the smooth locus over @xmath255 , and we denote by @xmath395 the component containing @xmath391 . there is a modular map @xmath396 as before . moreover , defining @xmath397 to be the open set of curves in @xmath398 not containing any exceptional curves in @xmath306 ( note that @xmath399 ) , we have the surjective map @xmath400 & \v^*_{\delta,\r_p}}\ ] ] sending @xmath401 , where @xmath402 and @xmath389 , to @xmath403 , where @xmath404 is the image of @xmath39 in @xmath207 under the natural contraction map @xmath405 . summarizing , we have the commutative diagrams @xmath406 \ar[urr]^{\psi'_{\delta } } & \v^*_{\delta,\mathfrak{s}_p } \ar@{->>}[l]^{\pi_{\delta } } \ar@{^{(}->}[r ] \ar[d ] \ar[ur ] & \v_{\delta}^ * \ar[d]^{\phi^*_{\delta } } \ar[u]_{\psi^*_{\delta } } \\ & \r_p & \mathfrak{s}_{p } \ar@{->>}[l]^{\pi_p } \ar@{^{(}->}[r ] & \overline{\k}_p } \ ] ] and @xmath407 & \w_{\delta } \ar@{^{(}->}[d ] \ar@{->>}[l]_{{\pi_\delta}_{|\w_\delta } } \\ & \v^*_{\delta,\r_p } & \v^*_{\delta,\mathfrak{s}_p } \ar@{->>}[l]^{\pi_{\delta } } } \ ] ] the fibers of @xmath408 are all @xmath260-dimensional ( isomorphic to a dense open subset of @xmath409 ) . this shows that the fibers of @xmath381 over curves that come from reducible @xmath0 surfaces have at least one component that has dimension at least @xmath260 . as @xmath410 ( the expected dimension of the general fiber ) for @xmath411 , this makes it difficult to prove theorem [ thm : main ] directly by semicontinuity around elements of @xmath397 . we will circumvent this problem in the next section , to prove theorem [ thm : main ] for @xmath52 . to this end we start by studying the fibers of the restriction of @xmath412 to @xmath391 . [ prop : unica1 ] let @xmath3 and @xmath413 . then the general fiber of @xmath414 has dimension at most @xmath415 . we will assume @xmath416 . the case @xmath417 is easier , can be treated in the same way and details can be left to the reader . the idea of the proof is to define , in step 1 below , an incidence variety @xmath418 , described in terms of the geometry of the quadric @xmath419 , and a surjective morphism @xmath420 , with fibers isomorphic to @xmath421 . rather than studying the moduli map @xmath422 , we will study its composition @xmath423 with @xmath424 , which can be described in terms of the geometry of @xmath425 . in step 2 we will study the fibers of @xmath423 . with @xmath419 , let @xmath426 for @xmath222 be the projections onto the factors . define @xmath427 and denote its elements by @xmath428 * step 1 : a basic construction*. consider the locally closed incidence scheme @xmath429 formed by all triples @xmath430 , with @xmath431 , @xmath432 , @xmath433 , such that : + [ @xmath434 @xmath78 is smooth ; + @xmath435 ( equivalently , @xmath436 for odd @xmath5 ) ; + @xmath437 is reduced ( in particular @xmath438 are distinct ) ; + @xmath439 and @xmath437 have no points in common , for @xmath222 . + the divisor @xmath440 is the one in definition [ def : nonpiaceraaconcy ] with @xmath441 defined by the projection @xmath442 , for @xmath222 . recall that @xmath443 when @xmath5 is odd . the projection of @xmath444 to @xmath445 is dominant , with general fiber of dimension @xmath446 , hence @xmath447 next we define a surjective map @xmath448 as follows : let @xmath449 and set @xmath450 , which is a degree @xmath181 divisor on @xmath78 . then @xmath451 defines , up to projective transformations , an embedding of @xmath78 as an elliptic normal curve @xmath452 . the degree 2 line bundles @xmath441 defined by the projections @xmath442 define rational normal scrolls @xmath453 , for @xmath222 , hence the surface @xmath202 . the hyperplane section of @xmath207 cutting out @xmath454 on @xmath78 defines a curve @xmath455 . one defines @xmath456 . the map @xmath457 is surjective . take a curve @xmath404 on @xmath458 corresponding to a point of @xmath391 and consider @xmath459 together with the @xmath460 projection maps @xmath461 , where @xmath310 is the residual curve to the line chain of @xmath404 on @xmath185 , cf . definition [ def : compopartenza ] . up to choosing an isomorphism @xmath462 , the map @xmath463 embeds @xmath78 as an anticanonical curve in @xmath425 . let @xmath464 be the unordered images of the intersection points @xmath465 and @xmath466 be the pair of distinguished points , ordered if @xmath5 is even , and unordered if @xmath5 is odd . this defines a point @xmath449 such that @xmath467 . this argument shows that the fibers of @xmath457 are isomorphic to @xmath468 . we have the commutative diagram @xmath469_{\sigma_{\delta } } \ar[rr]^{\vartheta_{\delta } } & & \w'_{\delta } \ar[d]^{(\psi'_{\delta})_{|\w'_{\delta } } } \\ & & \overline{\m}_g } \ ] ] where @xmath470 is the composition map . it can be directly defined as follows . take @xmath449 . call @xmath471 and @xmath472 the two @xmath194s such that @xmath473 . we have the @xmath35 points @xmath474 , for @xmath222 and @xmath475 . if @xmath5 is even , we get additional points @xmath476 and @xmath477 . if @xmath5 is odd we get two more points @xmath478 on @xmath471 . then @xmath479 is obtained ( recalling figure [ fig : dis ] ) in one of the following ways : + [ @xmath434 when @xmath5 is even , by gluing @xmath471 and @xmath472 with the identification of @xmath480 with @xmath481 , for @xmath482 ; in the case @xmath483 , we furthermore contract @xmath472 , thus identifying @xmath484 and @xmath485 on @xmath471 . + when @xmath5 is odd , by first identifying @xmath486 and @xmath487 on @xmath471 and then gluing with @xmath472 by identifying the points @xmath480 with @xmath481 , for @xmath475 ; in the cases @xmath488 , we furthermore contract @xmath472 ( when @xmath489 , this identifies @xmath484 and @xmath485 on @xmath471 , whereas if @xmath483 , the curve @xmath472 is contracted to a smooth point and no further node is created ) . + * step 2 : the fiber . * by step 1 , to understand the general fiber of @xmath414 , it suffices to understand the general fiber of @xmath470 . this is what we do next . consider a general element @xmath490 in @xmath491 . then @xmath492 is a union of two rational components when @xmath314 or @xmath489 and @xmath5 is even ( recall figure [ fig : dis ] ) . if @xmath489 and @xmath5 is odd , then @xmath490 is a rational curve with two nodes and we will substitute @xmath490 with the stably equivalent curve @xmath493 where @xmath494 is the normalization of @xmath490 at one of the nodes and @xmath495 is attached to it at the two inverse images of the node . ( the dimensional count that follows does not depend on the choice of the node on @xmath471 and the two matching points on @xmath496 , as we will show below ) . if @xmath483 , then @xmath490 is a rational curve with one node . when @xmath5 is even , we will substitute @xmath490 with the stably equivalent curve @xmath493 where @xmath497 is the normalization of @xmath490 and @xmath495 is attached to it at the two inverse images of the node . when @xmath5 is odd , we will substitute @xmath490 with the stably equivalent curve @xmath493 where @xmath498 and @xmath499 is attached to an arbitrary smooth point of @xmath494 . ( the choice of the matching points on @xmath494 and @xmath496 will again not influence the dimensional count that follows . ) thus , after the substitution , the curve @xmath490 looks exactly as one of the curves on the right in figure [ fig : dis ] . denote by @xmath471 and @xmath472 the normalizations of @xmath494 and @xmath496 , respectively , both isomorphic to @xmath194 , so that @xmath500 , up to the action of @xmath421 ( which will contribute to the fiber of @xmath423 ) . all curves @xmath501 stably equivalent to @xmath490 constructed above for @xmath502 and @xmath5 odd and @xmath483 and @xmath5 even are equivalent by this action . if @xmath5 is odd , then @xmath503 , whereas @xmath494 has one node . on @xmath500 we have the @xmath35 points @xmath504 , for @xmath475 , which are identified in @xmath490 . in addition , we have the divisor @xmath505 over the node of @xmath494 . then the @xmath470fiber of @xmath490 consists of all @xmath506 such that @xmath78 is a smooth curve in @xmath507 satisfying the additional condition @xmath508 if @xmath5 is even , then @xmath509 , for @xmath222 , and the intersection points between the two components yield @xmath446 points @xmath510 , for @xmath511 . then the @xmath470fiber of @xmath490 is the union of @xmath446 components obtained in the following way . choose an index @xmath512 , e.g. , @xmath513 . then the corresponding component of the fiber consists of all @xmath506 such that @xmath78 is a smooth curve in @xmath507 satisfying the additional condition @xmath514 either way , up to the action of @xmath515 , the @xmath423fiber of @xmath490 is contained in @xmath507 , and , by assumption , we know that there are smooth curves @xmath516 . hence @xmath517 , which proves the assertion if @xmath518 . ( this is clear if @xmath519 ; if @xmath520 , the projection @xmath521 is dominant , whence we may assume that @xmath522 are general points in @xmath425 . ) to finish the proof , we have to prove that for @xmath523 and for a general choice of @xmath506 , condition or defines a proper , closed subscheme of @xmath507 . let @xmath5 be odd . let us fix a general point @xmath524 and let us take a general curve @xmath525 . consider the point @xmath526 . fix then another general @xmath527 , which neither contains @xmath322 nor its conjugate on @xmath78 via @xmath278 . the curves @xmath78 and @xmath188 intersect at @xmath528 distinct points off @xmath321 choose @xmath438 among them . then @xmath529 , and @xmath78 satisfies ( with @xmath530 ) , whereas @xmath188 does not . the proof for @xmath5 even is similar and can be left to the reader . [ cor : unica1 ] let @xmath50 , @xmath531 and @xmath532 . set @xmath533 and @xmath534 , cf . and . there is at least one component @xmath535 of @xmath536 containing the whole fiber @xmath537 , and any such @xmath535 satisfies + @xmath538 ; + @xmath539 . \(a ) as mentioned above , the fiber @xmath540 is isomorphic to a dense open subset of @xmath541 , and it is contained in @xmath542 . hence there is at least one component @xmath535 of @xmath536 containing the whole fiber @xmath537 and any such component contains some @xmath543 satisfying that @xmath544 for a _ general _ element @xmath545 . due to the generality of @xmath79 , the surface @xmath163 lies off the closure of the noether lefschetz locus in @xmath1 ( see @xcite ) . thus , there can be no element @xmath546 with @xmath20 smooth , because @xmath547 , whereas @xmath39 is reducible , its class in moduli being @xmath548 . so , if @xmath546 , then @xmath549 . thus @xmath550 . if @xmath551 , there is nothing more to prove . so assume there is a disc @xmath552 parametrizing pairs @xmath553 such that @xmath554 , with @xmath555 and @xmath556 , for all @xmath557 , with @xmath558 . consider @xmath559 , and the divisor @xmath560 on @xmath561 along which the modification @xmath562 takes place . as @xmath563 , we may assume that @xmath564 for all @xmath565 . hence @xmath566 , which has @xmath5 marked nodes on the smooth locus of @xmath567 , for all @xmath565 . these nodes lie on lines contained in @xmath568 . as @xmath569 contains precisely one connected chain of lines ( i.e. , its line chain , see definition [ def : compopartenza ] ) , the same holds for @xmath568 for all @xmath565 . hence @xmath570 , so that @xmath571 . this proves ( i ) . assertion ( ii ) then follows from proposition [ prop : unica1 ] . in this section we will prove the part of theorem [ thm : main ] concerning the case @xmath52 . we circumvent the problem of the `` superabundant '' fibers of @xmath572 remarked in the previous section by passing to ( a component of ) the universal severi variety over the hilbert scheme @xmath208 , which is the pullback of the universal severi variety @xmath365 over the locus of smooth , irreducible @xmath0 surfaces . [ prop : unica2 ] let @xmath3 . one has : + the map @xmath572 is generically finite for @xmath573 . + the map @xmath572 is dominant for @xmath574 . there exists a dense , open subset @xmath575 , disjoint from @xmath256 , such that there is a dominant moduli morphism @xmath576 & \k_p \subset \overline{\k}_p.}\ ] ] we consider the cartesian diagram @xmath577_{\phi_{\delta}^{\circ } } \ar[rr]^ { \nu_p } & & \v^*_{\delta } \ar[d]^{\phi^*_{\delta } } \\ \h^{\circ}_p\ar[rr ] _ { \mu_p } & & \overline{\k}_p } \ ] ] which defines , in the first column , ( a component of ) a _ universal severi variety _ over @xmath578 . accordingly , we can then consider the moduli map @xmath579 fitting in the commutative diagram @xmath580_{\psi^{\circ}_{\delta } } \ar[rr]^ { \nu_p } & & \v^*_{\delta } \ar[d]^{\psi^ * _ { \delta}}\\ & & \overline{\m}_g } \ ] ] and it suffices to prove that the general fiber of @xmath581 has dimension @xmath582 the equality due to the assumptions on @xmath35 . we prove this by semicontinuity . to this end we introduce a partial compactification @xmath583 of @xmath584 fitting into the commutative diagram @xmath577_{\phi^{\circ}_{\delta } } \ar@{^{(}->}[r ] & \mathfrak v_{\delta } \ar[d]^{\phi_{\delta } } \\ \h^{\circ}_p \ar@{^{(}->}[r ] & \h_p } \ ] ] the fiber of @xmath585 over any element @xmath586 contains the varieties @xmath383 by proposition [ prop : rightdim ] ( and definition [ def : componente ] ) . possibly after substituting @xmath583 with a dense , open subset ( still containing the varieties @xmath383 ) , we have a natural moduli map @xmath587 extending @xmath581 . take general @xmath588 and @xmath589 and set @xmath590 , cf . and . by semicontinuity , it suffices to prove that any component @xmath591 of @xmath592 passing through @xmath593 has dimension at most @xmath594 . this will be done by first bounding the dimension of @xmath595 and then bounding the dimension of all possible deformations of @xmath593 in @xmath591 outside of @xmath596 . we make this more precise as follows . let @xmath597 be the reduced affine tangent cone to @xmath591 at @xmath598 . consider the linear map @xmath599 & t_{\h_p , r'}\ar[r ] & h^0(t^1_{r ' } ) , } \ ] ] defined by composing the differential @xmath600 of @xmath585 at @xmath593 with the map , and its restriction @xmath601 to @xmath597 . by standard deformation theory , @xmath602 coincides with the affine tangent cone to @xmath595 at @xmath598 . therefore , @xmath603 and we are done once we prove that @xmath604 and @xmath605 * proof of :* under the @xmath606-quotient map@xmath607 \ar[d]^{\phi_{\delta } } & \v^*_{\delta,\r_p } \ar[d]\\ \r'_p \ar[r ] & \r_p } \ ] ] the variety @xmath595 is mapped with fibers of dimension @xmath608 to a variety @xmath609 intersecting @xmath391 . the component @xmath535 of @xmath610 containing @xmath611 ( cf . and ) lies in @xmath366 and satisfies @xmath612 by corollary [ cor : unica1 ] . therefore @xmath613 by the surjectivity of @xmath408 , proving . * proof of :* we may assume that @xmath591 contains a one parameter family containing @xmath593 and such that its general point is a pair @xmath27 with @xmath614 , otherwise @xmath615 and there is nothing more to prove . we claim that @xmath20 has at most isolated singularities . indeed , suppose @xmath20 is singular along a curve @xmath616 and let @xmath617 be the total space of the family . then the flat limit of @xmath616 on the central fiber sits in the singular locus scheme of @xmath207 , which is @xmath188 . since @xmath188 is a general elliptic normal curve ( hence it is smooth and irreducible ) , then also @xmath616 is an elliptic normal curve and @xmath20 , as well as @xmath207 , has simple normal crossings along @xmath616 . then @xmath617 has normal crossings along the surface which is the total space of the family of singular curves of the surfaces @xmath20 . let @xmath618 be the normalization of @xmath617 . the central fiber of @xmath618 consists of two smooth connected components , i.e. , the proper transforms of @xmath192 and @xmath193 . this implies that the general fiber of @xmath618 is also disconnected , consisting of two smooth components isomorphic to @xmath192 and @xmath193 . therefore the general fiber @xmath20 of @xmath617 sits in @xmath619 , a contradiction , which proves the claim . since @xmath20 has ( at most ) isolated singularities and degenerates to @xmath207 , it must have at worst @xmath620singularities , so it is a projective model of a smooth @xmath0 surface . thus we may find a one dimensional family @xmath621 of points in @xmath379 parametrized by the disc @xmath622 , such that @xmath623 and @xmath624 ( that is , @xmath163 is a birational modification of @xmath207 ) , @xmath625 is the total transform of a @xmath626 on @xmath207 , @xmath627 for all @xmath628 , and @xmath629 is smooth for all @xmath630 . since @xmath490 has @xmath446 nodes , the curves @xmath631 ( including @xmath625 ) have at least @xmath446 _ unmarked _ nodes mapping to the nodes of @xmath490 through the process of partial normalization at the @xmath5 marked nodes and possibly semi - stable reduction . on @xmath625 they must lie on the smooth locus of @xmath163 . ( indeed , it is well - known , and can be verified by a local computation , that a node of a limit curve lying on @xmath78 smooths as @xmath163 smooths , cf . e.g. @xcite , @xcite or ( * ? ? ? * pf . of lemma 3.4 ) . ) this means that these nodes of @xmath625 lie on the exceptional curves of the morphism @xmath405 . therefore the @xmath35 intersection points @xmath632 ( all lying on the elliptic curve @xmath188 ) plus one ( at least ) among the intersections of the line cycle of @xmath633 with the elliptic curve @xmath188 are contained in the divisor @xmath634 . hence , we have @xmath635 , and if @xmath636 , we have @xmath637 for any irreducible component @xmath638 of @xmath597 , proving . therefore , we have left to prove that the case @xmath639 can not happen . to this end , assume @xmath639 . the above argument shows that the @xmath35 intersection points @xmath632 plus a point @xmath640 are the zeroes of a section of @xmath641 , for some integer @xmath642 ( cf . definition [ def : nonpiaceraaconcy ] ) . if @xmath5 is odd , the @xmath35 intersection points @xmath632 are in @xmath643 . it follows that @xmath644 which implies that @xmath108 is uniquely determined , hence also the line chain of @xmath626 is , contradicting the fact that @xmath626 is general in @xmath383 . if @xmath5 is even , the @xmath35 intersection points @xmath632 are in @xmath645 if @xmath272 is odd , combining ( with @xmath646 replaced by @xmath321 ) with yields @xmath647 which implies only finitely many choices for @xmath321 , and we get a contradiction as before . if @xmath272 is even , then , with @xmath108 and @xmath646 replaced by @xmath321 and @xmath108 respectively , combined with yields @xmath648 which , together with gives a non - trivial relation between @xmath649 and @xmath279 , a contradiction . at this point , the proof of theorem [ thm : main ] for @xmath52 is complete ( noting that the assertion is trivial for @xmath650 ) . in order to treat the case @xmath82 we need to consider more limits of nodal curves on surfaces in @xmath231 . they are similar to the ones constructed by x. chen in @xcite . [ def : curvedichen ] for each @xmath21 , @xmath651 and the corresponding @xmath652 , we define @xmath653 to be the locally closed subset of curves of the form @xmath654 where : + @xmath655 for @xmath222 and @xmath656 ; + @xmath657 for @xmath656 and @xmath658 if @xmath659 is odd ; + @xmath660 for @xmath656 and @xmath661 if @xmath662 is even ; + there are points @xmath663 on @xmath188 such that @xmath664 if @xmath13 is odd , and @xmath665 if @xmath13 is even . we denote by @xmath666 the set of total transforms of the curves in @xmath667 passing through two points of @xmath79 different from @xmath322 . we remark that the curves in @xmath667 ( or @xmath668 ) are tacnodal at @xmath322 and , for even @xmath13 , also at @xmath669 with @xmath670 odd . figure [ fig : dischen ] depicts a member of @xmath671 for odd @xmath13 . the intersections on @xmath188 ( which are not all shown in the figure ) are marked with dots and are all transversal except at @xmath322 . the case of @xmath13 even is similar , except that the intersections at @xmath672 and @xmath673 are tangential . @xmath674{curvechen1.eps}\ ] ] [ fig : dischen ] [ lem : clear ] we have @xmath675 and @xmath676 . it is easily seen that any of the three maps @xmath677 mapping @xmath404 to @xmath678,@xmath679 and @xmath680 , respectively , is an isomorphism , proving the lemma . [ prop : curvedichen ] for any @xmath21 , the curves in @xmath668 deform to a set @xmath681 of rational _ nodal _ curves in @xmath6 on the general @xmath19 \in \k_p$ ] . more precisely , there is a @xmath18-dimensional subvariety @xmath682 with a partial compactification @xmath683 whose fiber over @xmath651 is @xmath668 and whose fiber @xmath681 over a general @xmath127 is a nonempty finite subset of @xmath684 . this follows the lines of proof in @xcite or ( * ? ? ? * proof of thm . 1.1 ) . for the reader s convenience , we outline here the main ideas , without dwelling on details . take a curve @xmath685 that is the total transform of a general curve @xmath686 . if @xmath659 is odd , then @xmath39 has a total of @xmath687 nodes on the smooth locus of @xmath163 : + [ @xmath434 two nodes occur on the two exceptional curves of @xmath306 that @xmath39 contains ; + the remaining nodes are the points @xmath688 for @xmath222 , @xmath689 , a total of @xmath690 times @xmath691 moreover , the point @xmath322 on @xmath39 is a @xmath692tacnode , which can be ( locally ) deformed to @xmath693 nodes for a general deformation of @xmath163 to a @xmath0 surface ( see @xcite , ( * ? ? ? 2.4 ) or ( * ? ? ? * thm 3.1 ) for a generalization of this result ) . since , by construction , @xmath39 does not contain subcurves lying in @xmath694 for any @xmath695 ( this is like saying that the aforementioned singularities of @xmath39 are non disconnecting ) , one checks that , for a general deformation of @xmath696 $ ] to a @xmath0 surface @xmath19 $ ] , the curve @xmath39 deforms to an irreducible , nodal curve in @xmath6 with a total of @xmath697 + \big[2mn-1\big]=2nm^2 + 1=p(m)\ ] ] nodes , as claimed . the case @xmath13 even is similar and can be left to the reader . in this section we will use proposition [ prop : unica2 ] and the curves in definition [ def : curvedichen ] to prove part @xmath49 of theorem [ thm : main ] for @xmath699 . we assume @xmath3 in the whole section . the following proposition fixes a gap in ( * ? ? ? 1.2 ) , whose proof is incomplete , cf . @xcite : [ lemma : solok3 ] let @xmath127 be general and @xmath21 be an integer . let @xmath144 be a fully complete component of @xmath33 . then the moduli map @xmath700 is generically finite . in particular this applies to any component of @xmath701 . by fully completeness , we have the filtration @xmath702}(s ) \cap v \subset v_{[m,\delta , { p(m)}-1]}(s ) \cap v \subset \ldots \subset v_{[m,\delta,\delta+1]}(s ) \cap v \subset v\ ] ] set @xmath703 } ( s ) \cap v ) $ ] , for @xmath704 , and @xmath705 . then we have @xmath706 where @xmath707 is a proper closed subvariety of @xmath708 for all @xmath709 . since @xmath551 , we have @xmath710 , which yields the first assertion . the final assertion follows by remark [ rem : imp ] . [ rem : generibassi ] the existence of fully complete components @xmath144 of @xmath33 for all @xmath711 , for a general @xmath712 , follows from the existence of irreducible nodal rational curves in @xmath6 proved in @xcite ( or by proposition [ prop : curvedichen ] ) . thus the general point in @xmath144 parametrizes an _ irreducible _ curve . in particular , proposition [ lemma : solok3 ] shows that the moduli map @xmath713 is dominant even when restricted to curves on a single general @xmath0 , for any @xmath21 . next we need a technical construction and a lemma . consider the commutative diagram @xmath714_{\phi^*_{\delta}}\ar[drr]^ { \psi^ * _ { \delta } } \ar[rr]^ { \widetilde \psi_\delta } & & \widetilde \m_{g_{1,\delta}}\ar[d]^{\varphi_{\delta } } \\ \overline { \k}_p & & \overline \m_{g_{1,\delta } } } \ ] ] where the triangle is the stein factorization of @xmath715 . we will abuse notation and we will identify an element @xmath716 with its image in @xmath717 . assume @xmath718 . by proposition [ prop : unica2 ] , given a general @xmath719 , the fiber @xmath720 is irreducible of dimension @xmath721 set @xmath722 which is irreducible and , by proposition [ lemma : solok3 ] , one has @xmath723 now we need to introduce the irreducible component @xmath724 of @xmath725 containing @xmath726 , whose fibre over @xmath712 we will denote by @xmath727 . consider a general @xmath97 . for any pair @xmath728 of positive integers , with @xmath729 ( hence @xmath730 ) , there are on @xmath20 finitely many curves of the form @xmath731where @xmath732 is as in proposition [ prop : curvedichen ] ( cf . definition[def : curvedichen ] ) . given a general @xmath733 , set @xmath734 , which is the ( class of the ) normalization @xmath735 of @xmath39 . for all @xmath736 , we have a morphism @xmath737 , whose image we denote by @xmath404 , and each of the curves @xmath738 on @xmath739 cuts out on @xmath404 a divisor , which can be pulled back to a divisor @xmath740 on @xmath490 , for @xmath741 . let @xmath742 be the incidence subvariety described by the points @xmath743 such that @xmath744 , with @xmath740 the divisor cut out by @xmath745 on @xmath490 , for all @xmath746 . then let @xmath747 be the image of @xmath748 in @xmath749 . [ lemma : fibra ] in the above setting : + @xmath750 ; + for the general @xmath736 the curves of the form @xmath751 ( with @xmath752 as in ) are nodal . we specialize @xmath753 to @xmath754 , set @xmath755 and @xmath756 , and prove the assertions ( i ) and ( ii ) in the limit situation for @xmath548 and @xmath757 . each @xmath758 contains a curve @xmath759 with @xmath760 . by the proof of proposition [ prop : unica2 ] , all components of @xmath761 have dimension at most @xmath762 . by we conclude that _ all _ components of @xmath757 have dimension precisely @xmath763 . in particular , this applies to the component @xmath764 , cf . , where @xmath535 is a component of @xmath536 satisfying the conditions in corollary [ cor : unica1 ] . we recall that @xmath535 contains @xmath765 and satisfies @xmath766 by corollary [ cor : unica1](b ) , and @xmath767 lies in the specialization of @xmath768 . therefore , recalling again , we have @xmath769 and the general fiber of @xmath770 has dimension @xmath771 ( remember the assumptions on @xmath772 and @xmath773 ) . then , inside @xmath767 we can find a subscheme @xmath774 of dimension at least @xmath775 consisting solely of surfaces that are birational modifications of a fixed @xmath207 and it is therefore parametrized by a family @xmath776 ( of dimension at least @xmath775 ) of divisors in @xmath259 . for @xmath163 corresponding to the general point of @xmath776 , the curves in @xmath777 are limits of rational nodal curves in @xmath778 for general @xmath779 , and similarly the curves in @xmath780 are limits of rational nodal curves in @xmath781 ( see proposition [ prop : curvedichen ] ) . we will prove that ( i ) and ( ii ) hold by proving that they hold in the limiting situation on @xmath163 . we first claim that for the general element @xmath782 , the curve @xmath783 is nodal off the tacnodes of @xmath784 . to prove the claim , note that for any @xmath785 , the variety @xmath786 parametrizes a @xmath787dimensional family of curves . its general element contains a line chain , that varies in a @xmath143dimensional , base point free system , so the lines of these chains are in general different from lines contained in the general member of @xmath788 and do not cause any non - nodal singularities in @xmath783 . fixing a line chain @xmath309 , the family of curves in @xmath786 containing it is a linear system @xmath789 of dimension @xmath790 , whose general element , minus @xmath309 , is a smooth rational curve on every @xmath197 , so that @xmath789 is base point free off @xmath309 whenever @xmath791 . hence , the general curves @xmath792 in @xmath793 intersect both @xmath625 and @xmath784 transversely , and if @xmath794 , then also the general @xmath625 in @xmath383 intersects @xmath784 transversely . it remains to prove that the latter holds also when @xmath795 , that is , when @xmath796 . as we saw , non - transversal intersections can only occur off the line chain of @xmath625 , that is , on the two components @xmath797 , @xmath222 , of @xmath625 . denote by @xmath798 , @xmath222 , @xmath799 the components of @xmath784 as in definition [ def : curvedichen ] . if @xmath659 is odd , then @xmath800 and @xmath801 , for @xmath222 and @xmath656 . hence @xmath310 only intersects the component @xmath658 of @xmath784 . as we vary the curves @xmath784 with fixed tacnode @xmath802 ( see definition [ def : curvedichen ] and figure [ fig : dischen ] ) , each component @xmath803 varies freely in the linear system @xmath804 , where @xmath752 is the length@xmath805 subscheme of @xmath188 supported at @xmath322 . this linear system is base point free off @xmath322 . it follows that each @xmath310 intersects the general @xmath803 transversely , whence @xmath625 intersects the general @xmath784 transversely . if @xmath662 is even , then @xmath806 , @xmath807 , @xmath808 and @xmath809 , for @xmath222 and @xmath656 . hence , @xmath810 and @xmath811 for @xmath656 and we again only need to check that @xmath310 intersects @xmath661 transversely , which can be proved exactly as in the case @xmath13 odd . this finishes the proof of the claim . since the curves @xmath812 move in an at least two - dimensional family , for @xmath741 , the curves @xmath813 cuts out on @xmath625 an algebraic system @xmath814 and the associated variety @xmath815 equals @xmath816 . hence , for the general @xmath772tuple of pairs of points of @xmath625 , we may find a @xmath817 such that @xmath818 contains the given points on @xmath625 and is nodal off the tacnodes of @xmath784 . each @xmath812 in @xmath818 cuts @xmath188 in @xmath181 points for @xmath819 and in at least 3 points off the tacnodes if @xmath820 . since @xmath821 , we can find a surface @xmath163 corresponding to a point of @xmath776 for which the modification @xmath822 involves two of the intersection points of each @xmath812 with @xmath188 for @xmath741 ( off the tacnodes if @xmath820 ) . we denote by @xmath823 the total transform of @xmath818 on @xmath163 . then @xmath824 , and we denote by @xmath825 the total transform of each @xmath812 on @xmath163 , for @xmath741 . then such a curve is the limit of a nodal rational curve in @xmath778 for @xmath819 , and @xmath826 is the limit of a nodal rational curve in @xmath781 . thus , we have proved that ( i ) and ( ii ) hold in the limiting situation for @xmath163 , @xmath625 and @xmath823 . hence , they also hold in general . let @xmath729 and @xmath827 be positive integers . then for @xmath19\in \k_p$ ] general we can consider the locally closed subset @xmath828 in @xmath829 consisting of all nodal curves of the form @xmath830 , with @xmath831 and @xmath752 as in . note that @xmath828 is non empty for @xmath19 $ ] general by lemma [ lemma : fibra ] and @xmath832 . in the same way , we have the universal family @xmath833 , with fiber @xmath828 over @xmath20 . marking all the nodes of a curve @xmath830 but two in the divisor @xmath740 cut out by @xmath738 on @xmath39 , for @xmath741 , one checks that the normalizations are @xmath120-connected , hence these curves lie in @xmath834 , where @xmath835 and @xmath836 , with stable models in @xmath837 as shown in figure [ fig : dis2 ] below . @xmath838{cfgk4.eps}\ ] ] in this way we determine ( at least ) an irreducible , fully complete component @xmath839 of @xmath840 with its moduli map @xmath841 ( note that @xmath842 . ) [ prop : dom ] let @xmath3 . let @xmath35 and @xmath772 be positive integers with @xmath843 , @xmath844 and @xmath845 . set @xmath846 . then , for any integer @xmath847 , the map @xmath848 is dominant . we keep the notation introduced above . take a general @xmath849 and let @xmath850 , for @xmath851 , be general pairs of points on @xmath490 . by proposition [ prop : unica2 ] and lemma [ lemma : fibra ] we may construct nodal curves @xmath852 where @xmath853 , @xmath854 and @xmath855 . the stable model @xmath856 of the curve obtained by normalizing @xmath857 at all the marked nodes , is the curve obtained by pairwise identifying the inverse images of the points @xmath858 on @xmath490 , for @xmath741 . this is , by construction , a general member of the @xmath772codimensional locus @xmath859 of irreducible @xmath772nodal curves in @xmath860 , which therefore sits in the closure of the image of @xmath848 . we claim that any component of @xmath861 is a whole component of @xmath862 . indeed , if it were not , then the general member of the component containing it would be a curve @xmath863 specializing to @xmath857 , which means that the normalization of @xmath863 at its marked nodes would consist of a component of arithmetic genus @xmath864 with @xmath865 nodes ( giving rise , in the specialization , to @xmath866 of the rational curves @xmath738 in @xmath857 ) , plus @xmath867 rational curves ( tending to the remaining curves @xmath738 in @xmath857 ) . in any event , @xmath863 has geometric genus @xmath35 . so the relative dimension over @xmath1 of such a family is @xmath35 , equal to the relative dimension of @xmath861 , a contradiction . it follows that the fiber dimension over @xmath859 is @xmath868 hence the general fiber of @xmath848 has at most this dimension , so @xmath869-[22 - 2(g+s)]=3(g+s)-3\ ] ] proving the assertion . [ cor : tutteledominanze ] assume @xmath50 . with @xmath870 , the map @xmath871 is dominant if : + @xmath54 , @xmath872 and @xmath55 ; + @xmath57 , @xmath873 and @xmath58 ; + @xmath60 , @xmath874 and @xmath61 ; + @xmath47 , @xmath875 and @xmath63 . for any @xmath876 , proposition [ prop : dom ] ensures dominance of @xmath871 if @xmath847 , @xmath877 and @xmath878 , proving the result . together with remark [ rem : generibassi ] , and the fact that the assertion is trivial for @xmath650 , this finishes the proof of theorem [ thm : main](a ) for @xmath698 . in this section we will use proposition [ prop : unica2 ] and corollary [ cor : tutteledominanze ] to prove generic finiteness of @xmath871 for @xmath82 as in theorem [ thm : main ] . [ lemma : finitezzasu ] if there exists a component @xmath879 such that @xmath880 is generically finite onto its image , then for each component @xmath881 such that @xmath9 is included in @xmath882 ( see remark [ rem : filtr ] ) , the map @xmath883 is generically finite onto its image . [ lemma : baseperfinitezza ] assume that @xmath884 and @xmath885 are integers such that @xmath886 is generically finite onto its image on a component @xmath887 of @xmath888 . let @xmath889 and @xmath890 be integers such that there is a component @xmath891 of @xmath892 satisfying : + pick general elements in @xmath887 and @xmath891 like in ( i ) , with @xmath902 and @xmath903 . then @xmath904 corresponds to a point of a component @xmath9 of @xmath905 , if we consider as marked nodes of @xmath906 all of its nodes but two in @xmath907 . let @xmath908 . this map sends @xmath906 to @xmath735 plus @xmath909 glued at two point ( with a further contraction of @xmath909 if @xmath910 ) . because of the hypotheses , the map @xmath915 is generically finite onto its image . hence @xmath916 . since the general element of @xmath917 is smooth , we must have @xmath918 . therefore , the general fiber of @xmath919 has dimension at most @xmath920-(20+\gamma+b)=0,\ ] ] and the result follows . let @xmath698 . if @xmath69 , we apply lemma [ lemma : baseperfinitezza ] with @xmath924 , @xmath925 , @xmath926 , @xmath910 , @xmath927 , the component for which we proved generic finiteness of @xmath928 in proposition [ prop : unica2 ] and @xmath929 the component consisting of rational curves that degenerate to a curves of the type @xmath780 as in definition [ def : curvedichen ] , cf . proposition [ prop : curvedichen ] . condition ( ii ) of lemma [ lemma : baseperfinitezza ] is satisfied and an argument as in the proof of lemma [ lemma : fibra ] shows that also condition ( i ) is satisfied . then lemma [ lemma : baseperfinitezza ] implies that @xmath159 is generically finite on a suitable component of the universal severi variety for @xmath930 . lemma [ lemma : finitezzasu ] yields that @xmath159 is generically finite on some component for all @xmath922 , as stated . if @xmath47 , @xmath48 and @xmath931 , the map @xmath159 is generically finite on some component of @xmath25 by corollary [ cor : tutteledominanze ] , hence lemma [ lemma : finitezzasu ] yields the same for all @xmath923 .

we consider modular properties of nodal curves on general @xmath0 surfaces . let @xmath1 be the moduli space of primitively polarized @xmath0 surfaces @xmath2 of genus @xmath3 and @xmath4 be the universal severi variety of @xmath5nodal irreducible curves in @xmath6 on @xmath7 . we find conditions on @xmath8 for the existence of an irreducible component @xmath9 of @xmath10 on which the moduli map @xmath11 ( with @xmath12 ) has generically maximal rank differential . our results , which for any @xmath13 leave only finitely many cases unsolved and are optimal for @xmath14 ( except for very low values of @xmath13 ) , are summarized in theorem [ thm : main ] in the introduction .

but , it can be confused with true right atrial mass in transthoracic echocardiogram , especially in patients with embolic events . in this case report , transthoracic echocardiography suggested the presence of a right atrial mass in patients with a pulmonary embolism . a 73-year - old woman was referred to our hospital for surgery due to tuberculosis spondylitis and concomitant ankylosis . her blood pressure was 110/70 mmhg , and her electrocariogram showed a normal sinus rhythm with a heart rate of 60 beats per minute . however , twenty days after surgery , the patient complained of dyspnea ; the arterial oxygen saturation was decreased to 82% , the d - dimer and b - type natriuretic peptide were increased to 9.73 ug / ml and 2,042 pg / ml , respectively . for evaluation of hypoxia , the transthoracic echocardiogram was perfomed and revealed right side cardiac chamber enlargements without right ventricular dysfunction . furthermore , a 2.2 2.4 cm homogenous non - mobile echogenic mass was found within the right atrium ( fig . because of this finding , we performed a transesophageal echocardiogram that showed the right atrial mass was actually a prominent crista terminalis ( fig . 2 ) . subsequent chest computed tomography ( ct ) and magnetic resonance imaging ( mri ) revealed findings consistent with a pulmonary embolism ( fig . 3 ) , deep vein thrombosis , and a prominent crista terminalis without any definite right atrial abnormal mass ( fig . the crista terminalis is a fibromuscular ridge derived from the regression of the septum spurium as the sinus venosus is incorporated into the right atrial wall.1 ) because of the variation of the regression process , the prominence of the crista terminalis varies widely in adults . pharr et al.2 ) reported that if the prominence of the crista terminalis is superior , it can appear as a right atrial mass on the transthoracic echocardiogram . 2 shows the prominence of the crista terminalis at the superior part of right atrium close to superior vena cava . however , there is no large study on the frequency and characteristics of a prominent crista terminalis with transthoracic echocardiography . furthermore , all seven patients previously reported in case studies of a prominent crista terminalis were women between the ages of 49 and 77 similar to the case reported here.2 - 6 ) therefore , the age and gender of patients with a prominent crista terminalis appear to be similar to the age and gender of patients with a myxoma . in our case , the patient presented pulmonary embolism after long term immobilization with finding of coincident right atrial mass , which could be misdiagnosed with thrombus or other intra - cardiac mass . recently , mckay and thomas4 ) reported that identification of physiologic structures in the right atrium using additional three dimensional ( 3d ) transthoracic imaging can avoid unnecessary tests such as transesophageal echocardiography or mri . thus , we thought that emerging 3d transthoracic imaging could be another alternative modality to differentiate the prominent crista terminalis from the true right atrial mass . in conclusion , transesophageal echocardiography , ct / mri , and 3d transthoracic imaging could be used to differentiate a prominent crista terminalis from a true right atrial mass . understanding of the right atrial anatomy is important to making an accurate diagnosis and to avoid unnecessary additional tests .

a prominent crista terminalis is a normal anatomic variant which consist of thick muscular bridge within the right atrium . however , it could be often misdiagnosed with an abnormal mass on the transthoracic echocardiography . the case report presented here , describe the findings of transthoracic echocardiography that suggested a right atrial mass in patients with pulmonary embolism . however , subsequent transesophageal echocardiography and cardiac computed tomography / magnetic resonance imaging differentiated a true right atrial mass from a prominent crista terminalis .

antibodies and immunoblotting the production of -sgo1 and -apc2 antibodies was described previously ( 9 , 21 ) . the following antibodies were purchased from commercial sources : crest ( immunovision ) , -cyclin b1 ( santa cruz biotechnology ) , -ha and -myc ( roche applied science ) . for immunoblotting , the antibodies were used at 1:2000 dilution for crude sera or 1 g / ml for purified igg . mammalian cell culture , drug treatments , and transfection hela tet - on ( clontech ) cells were grown in dulbecco 's modified eagle 's medium ( invitrogen ) supplemented with 10% fetal bovine serum and 10 mm l - glutamine . to arrest cells at g1/s , cells were incubated in growth medium containing 2 mm thymidine ( sigma ) for 18 h. to arrest cells in mitosis , cells were treated with 300 nm nocodazole ( sigma ) for 16 - 18 h or as indicated . cycloheximide was added to the medium when needed at a concentration of 50 m . plasmid transfection was performed when cells reached 50% confluency using the effectene reagent ( qiagen ) according to the manufacturer 's protocols . , hela cells were transfected using lipofectamine rnaimax ( invitrogen ) according to manufacturer 's protocols and analyzed 36 - 48 h after transfection . for rnai experiments , the sequences of the sirnas used in this study are bub1-targeting sirna oligonucleotide ( gagugaucacgauuucuautt ) and sgo1 sirna ( gaggggacccuuuuacagatt ) . to establish stable cell lines , hela tet - on cells were transfected with ptre2-myc based plasmids encoding myc - sgo1 and myc - sgo1 , and selection of stable clones was performed in the presence of 300 g / ml hygromycin . the surviving clones were screened for the induced expression of corresponding myc - tagged proteins in the absence or presence of 1 g / ml doxycycline ( clontech ) . mitotic cells were harvested by shake - off and swelled in a prewarmed hypotonic solution containing 55 mm kcl for 15 min at 37 c . cells were spun onto microscope slides at 1500 rpm for 4 min using a shandon cytospin centrifuge . images were acquired and processed with the slidebook software ( intelligent imaging ) and pseudocolored in photoshop . a series of z - stack images were captured at 0.2 - 0.3-m intervals and deconvolved using the nearest neighbor algorithm . the maximum z - projection is then created for the deconvolved images . for the analysis of chromosome morphology , a giemsa staining protocol was used as described ( 22 ) . in vitro translation and ubiquitination assays the in vitro transcription and translation system was purchased from promega , and the reactions were performed according to the manufacturer 's instructions . briefly , 80 ng of plasmid dna , nuclease - free water , 0.2 l of [ s]methionine ( 10 ci/l ) , and 4 l of rabbit reticulocyte lysate were mixed to give a final volume of 5 l . the interphase apc / c was purified from interphase xenopus egg extracts using anti - apc3/cdc27 antibody coupled to protein a support as described ( 23 , 24 ) . the expression and purification of human cdc20 and cdh1 proteins from sf9 cells each ubiquitination assay contained a 5-l mixture of an energy - regenerating system , 150 m ubiquitin , 5 m recombinant ubiquitin - activating enzyme , 2 m recombinant ubch10 , 1 l of in vitro transcribed and translated substrates , and 3 l of the apc / c beads . live - cell imaging for live - cell imaging , egfp - h2b - expressing cells were plated in 4-well chambered coverslips ( labtek ) and synchronized in early s - phase by thymidine arrest for 18 h and released into fresh medium just before filming . cells were imaged in co2-independent medium ( invitrogen ) at 37 c using a deltavision microscope . 3 z - stacks were acquired every 2 min for 24 h. image manipulations were performed in imagej ( contrast enhancement , cropping , and conversion to quicktime ) . sgo1 is degraded during mitotic exit , and its degradation depends on cdh1previous studies have shown that the protein level of sgo1 in nocodazole - arrested mitotic cells is higher than that of sgo1 in cells enriched in g1/s phase by thymidine arrest ( 9 ) , suggesting that sgo1 levels are regulated during the cell cycle . to confirm this finding hela cells were arrested in mitosis by nocodazole treatment and released into fresh medium . then cells were harvested at different time points , and sgo1 proteins levels were analyzed by western blotting . the sgo1 protein level was high in mitosis but dropped sharply upon nocodazole release ( fig . , the protein level of apc2 remained unchanged , serving as a loading control . many proteins , including cyclin b1 , undergo rapid degradation during mitotic exit to coordinate exit from mitosis . a sharp decrease in sgo1 protein level suggests that this protein is degraded during mitotic exit . in addition to the band at about 80 kda that corresponded to the full - length sgo1 , we observed two additional bands of smaller sizes ( fig . it is well documented that sgo1 has several isoforms produced by alternative splicing ( 11 ) . these two smaller protein bands had sizes corresponding to the proteins produced from two major sgo1 splice variants , suggesting that they very likely were sgo1 isoforms ( 26 , 27 ) . their protein levels were reduced upon release from nocodazole in the same fashion as the full - length sgo1 , suggesting that they too were degraded during mitotic exit . many proteins degraded during mitotic exit , such as cyclin b1 , bub1 , or plk1 , are substrates for apc / c . the xenopus sgo1 protein has been shown to be a substrate of apc / c ( 8) . we next tested that human sgo1 was a substrate of apc / c . we transfected hela cells with myc - sgo1 in the absence or presence of ha - cdh1 . overexpression of cdh1 greatly reduced the protein levels of myc - sgo1 , supporting that sgo1 was a substrate for apc / c ( fig . apc substrates generally contain cis - elements , such as d boxes or ken boxes , required for their ubiquitination . we carefully inspected the sequence of sgo1 and identified a putative ken box corresponding to residues 310 - 312 of human sgo1 . we also found two putative d boxes with a consensus motif of rxxlxxxn in human sgo1 at residues 192 - 200 and 457 - 465 ( fig . 1 , c and d ) . both mouse and xenopus sgo1 proteins contain an rxxlxxxxn motif that corresponds to residues 438 - 446 in human sgo1 , except that human sgo1 contains a histidine instead of an arginine at position 438 . we decided to consider residues 438 - 446 as a putative d box in human sgo1 . we named it d box 2 ( db2 ) , whereas two others were named d box 1 ( db1 ) and d box 3 ( db3 ) accordingly ( fig . db2 and db3 are located next to each other in the c - terminal portion of sgo1 . db1 and db3 are not conserved in mouse and xenopus sgo1 , whereas db2 is conserved with the exception of the first arginine ( fig . a , hela cells were arrested in mitosis by nocodazole ( noc ) , released into fresh growth medium , and collected at the indicated time points . the cell lysates were immunoprecipitated with anti - sgo1 , and the anti - sgo1 immunoprecipitates were blotted with anti - sgo1 . the cell lysates were also blotted with anti - cyclin b1 and anti - apc2 ( loading control ) . b , hela cells were transfected with the indicated sgo1 plasmids with or without the ha - cdh1 construct . the putative apc / c degrons , the coiled coil motif , and the basic domain are indicated . d , sequence alignment of the c - terminal regions of human , mouse , and xenopus sgo1 proteins , showing the conservation of the putative d box 2 ( db2 ) but not db1 or db3 . a , hela cells were arrested in mitosis by nocodazole ( noc ) , released into fresh growth medium , and collected at the indicated time points . the cell lysates were immunoprecipitated with anti - sgo1 , and the anti - sgo1 immunoprecipitates were blotted with anti - sgo1 . the cell lysates were also blotted with anti - cyclin b1 and anti - apc2 ( loading control ) . b , hela cells were transfected with the indicated sgo1 plasmids with or without the ha - cdh1 construct . the putative apc / c degrons , the coiled coil motif , and the basic domain are indicated . d , sequence alignment of the c - terminal regions of human , mouse , and xenopus sgo1 proteins , showing the conservation of the putative d box 2 ( db2 ) but not db1 or db3 . to determine whether these motifs were important for sgo1 degradation , we first made mutants with either db1 or db3 deleted ( db1 or db3 ) , as they both had a perfect consensus motif . we also made a mutant with the ken box deleted ( ken ) and a double mutant with both db3 and the ken box deleted ( ken/db3 ) . hela cells were transfected with these myc - sgo1 mutant constructs with or without the ha - cdh1 expression vector , and the protein levels were examined by western blotting . the protein levels of all sgo1 mutants were still reduced by cdh1 overexpression ( fig . these data suggest that either those motifs are not functional , or deletion of each motif alone may not be sufficient to stabilize sgo1 . it is also possible that db2 or other degradation motifs may mediate sgo1 degradation . degradation of sgo1 requires both ken- and d - box motifs to systematically identify what regions of sgo1 were important for its degradation , we made three constructs containing n - terminal ( sgo1n ) , middle ( sgo1 m ) , or c - terminal ( sgo1c ) fragments of sgo1 ( fig . these constructs were expressed in hela cells in the absence or presence of cdh1 overexpression . 2b , lanes 1 and 2 ) , consistent with the lack of putative degradation motifs in this region . by contrast , the protein levels of both myc - sgo1 m and myc - sgo1c were reduced by cdh1 overexpression , suggesting that both fragments might be substrates of apc / c and that sgo1 might have multiple degradation motifs ( fig . 2b , lanes 3 , 4 , 9 , and 10 ) . to determine which degradation motifs in sgo1 m were functional , we made two sgo1 m constructs lacking either ken box or db1 and examined their protein levels in hela cells ( fig . deletion of the ken box , but not db1 , stabilized sgo1 m in the presence of cdh1 overexpression . the ken box is a functional apc / c degron capable of driving efficient degradation of sgo1 m . removal of this motif alone , however , was insufficient to stabilize full - length sgo1 protein in the presence of overexpressed cdh1 ( fig . 1b , lanes 3 and 4 ) , suggesting that sgo1 might have several degradation motifs . 2b , lanes 9 and 10 ) , suggesting that an additional degradation motif(s ) was present in this region . deletion of the putative db3 did not stabilize sgo1c in the presence of cdh1 overexpression ( fig . 2b , lanes 11 and 12 ) , indicating that this motif was not functional . to determine whether db2 was critical for the degradation of sgo1c , we made several constructs of sgo1c with consecutive deletions of 5 residues in the region containing residues 440 - 469 in sgo1 . overexpression of cdh1 did not reduce protein levels of sgo1c and sgo1c ( fig . db2 was partially deleted in both of these mutants , indicating that db2 was required for cdh1-dependent degradation of sgo1c . by contrast , other sgo1c mutants with residues neighboring db2 deleted were not stabilized . consistent with the putative db3 not being functional , two sgo1c constructs with db3 partially deleted , sgo1c and sgo1 , were still degraded by cdh1 overexpression . thus , degradation of sgo1 in the presence of an excess amount of cdh1 depends on both its ken - box and db2 , suggesting that sgo1 might be an apc / c substrate with multiple degrons . figure 2.sgo1 degradation induced by cdh1 overexpression depends on both its ken and d boxes . a , schematic diagram of the boundaries of the n - terminal ( sgo1n ) , middle ( sgo1 m ) , and c - terminal ( sgo1c ) fragments of sgo1 . b , hela cells were transfected with the indicated sgo1 plasmids with or without the ha - cdh1 construct . c , hela cells were transfected with the indicated sgo1 plasmids with or without the ha - cdh1 construct . sgo1 degradation induced by cdh1 overexpression depends on both its ken and d boxes . a , schematic diagram of the boundaries of the n - terminal ( sgo1n ) , middle ( sgo1 m ) , and c - terminal ( sgo1c ) fragments of sgo1 . b , hela cells were transfected with the indicated sgo1 plasmids with or without the ha - cdh1 construct . c , hela cells were transfected with the indicated sgo1 plasmids with or without the ha - cdh1 construct . figure 3.ubiquitination of sgo1 by apc / cin vitro depends on its ken and d boxes . a , apc / c was immunoprecipitated from xenopus egg extracts using anti - apc3/cdc27 antibody beads and supplemented with recombinant cdc20 or cdh1 . sgo1n , sgo1 m , and sgo1c were in vitro translated in the presence of [ s]methionine and used as substrates in the ubiquitination reactions . b , same as in a except that sgo1c deletion mutants were used as substrates for ubiquitination with or without cdh1 . ubiquitination of sgo1 by apc / cin vitro depends on its ken and d boxes . a , apc / c was immunoprecipitated from xenopus egg extracts using anti - apc3/cdc27 antibody beads and supplemented with recombinant cdc20 or cdh1 . sgo1n , sgo1 m , and sgo1c were in vitro translated in the presence of [ s]methionine and used as substrates in the ubiquitination reactions . b , same as in a except that sgo1c deletion mutants were used as substrates for ubiquitination with or without cdh1 . sgo1 is ubiquitinated by apc / c in vitro to confirm that human sgo1 was a substrate for apc / c , we tested whether immunopurified apc / c or apc / c could catalyze ubiquitination of sgo1 in vitro . the three sgo1 fragments ( sgo1n , sgo1 m , and sgo1c ) were translated in vitro in the presence of [ s]methionine and used as substrates in ubiquitination assays . 3a , lanes 1 - 3 ) , consistent with its inability to undergo cdh1-mediated degradation in cells . both sgo1 m and sgo1c were efficiently ubiquitinated by apc / c but not by apc / c ( fig . the significance of this ubiquitination event was unclear and was not further pursued . sgo1 m was not ubiquitinated ( data not shown ) , indicating that ubiquitination of this region occurs via the ken box . 2c , sgo1c and sgo1c that contained deletions of db2 were not efficiently ubiquitinated by apc / c ( fig . deletions of db3 and other residues near db2 did not prevent the ubiquitination of sgo1c ( fig . our results indicate that sgo1 is a substrate of apc / c in vitro and that it contains two functional apc / c degrons , the ken box and db2 . figure 4.sgo1 with its ken and d boxes deleted is stable during mitotic exit . a , hela cells were transfected with the indicated sgo1 plasmids with or without the ha - cdh1 construct . b , hela tet - on cells stably transfected with myc - sgo1 or sgo1 ( referred to as non - degradable sgo1 or sgo1 ) were incubated for 24 h in the presence or absence of doxycycline ( dox ) . c , cell lysates in b and lysates of an additional sgo1 clone were blotted with anti - sgo1 . d , hela cells induced with doxycycline for sgo1 or sgo1 expression were treated with nocodazole , released into a fresh medium containing cycloheximide , and collected at different time points . e , mitotic chromosome spreads of hela tet - on cells stably expressing myc - sgo1 or myc - sgo1 in the presence of doxycycline . a , hela cells were transfected with the indicated sgo1 plasmids with or without the ha - cdh1 construct . b , hela tet - on cells stably transfected with myc - sgo1 or sgo1 ( referred to as non - degradable sgo1 or sgo1 ) were incubated for 24 h in the presence or absence of doxycycline ( dox ) . c , cell lysates in b and lysates of an additional sgo1 clone were blotted with anti - sgo1 . d , hela cells induced with doxycycline for sgo1 or sgo1 expression were treated with nocodazole , released into a fresh medium containing cycloheximide , and collected at different time points . e , mitotic chromosome spreads of hela tet - on cells stably expressing myc - sgo1 or myc - sgo1 in the presence of doxycycline . sgo1 with the ken box and db2 deleted is stabilized during mitotic exit we next tested whether deletion of both the ken box and db2 stabilized full - length sgo1 in hela cells overexpressing cdh1 . as expected , deletion of either ken or db2 alone was not sufficient to stabilize sgo1 in the presence of cdh1 overexpression ( fig . deletion of both motifs , however , greatly stabilized sgo1 in cells overexpressing cdh1 ( fig . thus , either the ken box or db2 of sgo1 is sufficient to drive its degradation in cells with elevated levels of cdh1 . we will hereafter refer to the sgo1 mutant with both ken and db2 deleted as non - degradable sgo1 ( sgo1 ) . we then established cell lines that stably expressed full - length myc - tagged wild - type sgo1 ( sgo1 ) or non - degradable sgo1 ( sgo1 ) driven by a tetracycline - inducible promoter . we verified that sgo1 expression was induced by doxycycline in these lines ( fig . blotting of the cell lysates with anti - sgo1 readily detected myc - sgo1 and myc - sgo1 in the presence of doxycycline but failed to detect the endogenous sgo1 protein ( fig . therefore , the expression levels of myc - sgo1 and myc - sgo1 were higher than that of the endogenous sgo1 . the signal for endogenous sgo1 was below the detectable level under these blotting conditions . next , we examined the kinetics of degradation of myc - sgo1 and myc - sgo1 in these cells after the release from nocodazole - mediated mitotic arrest by blotting the total cell lysates with anti - myc . as expected , myc - sgo1 was degraded rapidly during mitotic exit , and its degradation profile was similar to that of cyclin b1 and the endogenous sgo1 ( fig . 4d , upper panels ) . by contrast , myc - sgo1 was degraded with a much slower kinetics , indicating that deletion of ken and db2 greatly impeded the degradation of sgo1 during mitotic exit . the kinetics of cyclin b1 degradation , however , was unchanged in cells expressing sgo1 ( fig . 4d , lower panels ) , suggesting that timely sgo1 degradation was not required for proper mitotic exit . to ascertain that sgo1 was still functional and that the mutations did not grossly affect the functions of sgo1 , we first examined the kinetochore localization of sgo1 . both myc - sgo1 and myc - sgo1 localized normally to centromeres ( fig . we next tested whether expression of sgo1 rescued the mitotic arrest phenotype of sgo1 rnai cells ( fig . 5 ) . for this purpose , we measured the mitotic indices of sgo1 rnai cells transfected with myc - sgo1 or myc - sgo1 using flow cytometry . as expected , depletion of sgo1 by rnai resulted in mitotic arrest ( fig . 5 , a and b ) . 5f ) rescued this mitotic arrest phenotype , indicating that myc - sgo1 was functional . ectopic expression of sgo1 does not delay chromosome segregation because human sgo1 is known to play a role in the protection of centromeric cohesion during mitosis ( 8 - 10 ) , we asked whether sgo1 degradation is required for proper chromosome segregation . briefly , hela cells expressing sgo1 or sgo1 were synchronized in mitosis by a single thymidine block followed by a 4-h incubation in nocodazole ( fig . mitotic cells were collected by mitotic shake - off and released from the mitotic block . these samples were fixed with carnoy 's fixative , processed for chromosome spreads , and stained with giemsa . cells expressing human sgo1 or sgo1 had chromosomes normally cohered at their centromeres , similar to their non - induced controls ( fig . 6b ) . furthermore , the timing of sister - chromatid separation and chromosome decondensation in the induced cells was indistinguishable from their non - induced controls ( fig . 6 , b and c ) . these data indicate that sgo1 degradation is not required for proper sister - chromatid separation or chromosome decondensation after release from a mitotic block . log phase hela cells ( a ) , sgo1 rnai cells ( b ) , cells transfected with myc - sgo1 ( c ) , cells transfected with both sgo1 and sgo1 sirna ( d ) , cells transfected with myc - sgo1 ( e ) , and cells transfected with both sgo1 and sgo1 sirna ( f ) were fixed and stained with the mpm2 antibody and propidium iodide and subjected to flow cytometry analysis . log phase hela cells ( a ) , sgo1 rnai cells ( b ) , cells transfected with myc - sgo1 ( c ) , cells transfected with both sgo1 and sgo1 sirna ( d ) , cells transfected with myc - sgo1 ( e ) , and cells transfected with both sgo1 and sgo1 sirna ( f ) were fixed and stained with the mpm2 antibody and propidium iodide and subjected to flow cytometry analysis . figure 6.expression of non - degradable sgo1 ( sgo1 ) does not delay chromosome segregation after the release from nocodazole - mediated mitotic arrest . a , schematic diagram of drug treatments for experiments shown in b and c. b , three major categories of chromosome morphology observed in chromosome spreads of hela tet - on cells stably transfected with myc - sgo1 in the absence or presence of doxycycline ( dox ) after the release from nocodazole - mediated mitotic arrest . c , kinetics of chromosome segregation in cells expressing myc - sgo1 or myc - sgo1 in the presence or absence of doxycycline after the release from nocodazole arrest . d , kinetics of chromosome decondensation in cells expressing myc - sgo1 or myc - sgo1 in the presence or absence of doxycycline after the release from nocodazole arrest . expression of non - degradable sgo1 ( sgo1 ) does not delay chromosome segregation after the release from nocodazole - mediated mitotic arrest . a , schematic diagram of drug treatments for experiments shown in b and c. b , three major categories of chromosome morphology observed in chromosome spreads of hela tet - on cells stably transfected with myc - sgo1 in the absence or presence of doxycycline ( dox ) after the release from nocodazole - mediated mitotic arrest . c , kinetics of chromosome segregation in cells expressing myc - sgo1 or myc - sgo1 in the presence or absence of doxycycline after the release from nocodazole arrest . d , kinetics of chromosome decondensation in cells expressing myc - sgo1 or myc - sgo1 in the presence or absence of doxycycline after the release from nocodazole arrest . a total of 100 chromosome spreads were analyzed for each sample . to confirm these findings , we examined the chromosome morphology and dynamics in cells overexpressing sgo1 or sgo1 during unperturbed mitoses . cells expressing sgo1 or sgo1 were synchronized in early s phase by a double thymidine block and released into fresh medium ( fig . samples were taken when cells reached their peak mitotic index and analyzed as described above . chromosome cohesion and morphology in the induced cultures were indistinguishable from their non - induced controls ( fig . all phases of mitosis were present at the expected ratios , indicating that the inability to degrade sgo1 does not induce changes in chromosome morphology or mitotic arrest . figure 7.expression of non - degradable sgo1 ( sgo1 ) does not delay chromosome segregation during unperturbed mitosis . a , schematic diagram of the time course of experiments in b. b , chromosome spreads of hela tet - on cells expressing sgo1 with or without doxycycline ( dox ) made 10 h after the release from the second thymidine block . expression of non - degradable sgo1 ( sgo1 ) does not delay chromosome segregation during unperturbed mitosis . a , schematic diagram of the time course of experiments in b. b , chromosome spreads of hela tet - on cells expressing sgo1 with or without doxycycline ( dox ) made 10 h after the release from the second thymidine block . figure 8.live cell time - lapse analysis of cells stably expressing non - degradable sgo1 . a , cells stably expressing non - degradable sgo1 ( sgo1 ) in the absence or presence of doxycycline ( dox ) were filmed for 20 h after release from thymidine arrest . selected frames of cells in interphase and different stages of mitosis time ( h : min ) is shown at the lower right corner of each image . b , cumulative frequency of cells undergoing anaphase within the indicated time windows after nuclear envelope breakdown . anaphase timing in hela tet - on cells expressing sgo1 and sgo1 was determined from time - lapse movies . live cell time - lapse analysis of cells stably expressing non - degradable sgo1 . a , cells stably expressing non - degradable sgo1 ( sgo1 ) in the absence or presence of doxycycline ( dox ) were filmed for 20 h after release from thymidine arrest . selected frames of cells in interphase and different stages of mitosis time ( h : min ) is shown at the lower right corner of each image . b , cumulative frequency of cells undergoing anaphase within the indicated time windows after nuclear envelope breakdown . anaphase timing in hela tet - on cells expressing sgo1 and sgo1 was determined from time - lapse movies . last , a detailed analysis of chromosome dynamics and anaphase timing was performed in live cells by time - lapse microscopy ( fig . 8a ) . both cells expressing sgo1 or sgo1 condensed their chromosomes , formed a metaphase plate , and underwent anaphase with similar timings ( fig . 8 , a and b ) . taken together , these results indicate that delayed sgo1 degradation does not prevent chromosome segregation and that sgo1 degradation is not required for later mitotic processes , such as chromosome decondensation and cytokinesis . bub1 regulates the steady - state level of sgo1 through an apc / c - independent mechanism it has been shown previously that the protein levels of sgo1 are reduced in bub1 rnai cells ( 9 ) , indicating that bub1 is required for the maintenance of the steady - state levels of sgo1 . bub1 also phosphorylates sgo1 protein in vitro at several sites , including ser-436 and ser-440 , which are in and around db2 ( data not shown ) . we , thus , tested whether bub1 regulated apc / c - dependent degradation of sgo1 . we depleted bub1 by rnai in cells stably expressing myc - sgo1 or sgo1 and blotted cell lysates with anti - myc . as expected , the levels of myc - sgo1 were regulated during the cell cycle and were lower in log phase cells than in thymidine- or nocodazole - arrested cells ( fig . depletion of bub1 further reduced the levels of sgo1 under all three conditions ( fig . the levels of sgo1 in log - phase cells were similar to that in thymidine- or nocodazole - arrested cells ( fig . 9 , lanes 10 - 12 ) , consistent with it not being regulated by apc / c . we expected that , if bub1 regulated sgo1 levels through preventing apc / c - dependent ubiquitination of sgo1 , then sgo1 should not display a reduction in protein levels in bub1 rnai cells . in contrast to our expectations , we found that the levels of sgo1 were still reduced in bub1 rnai cells ( fig . thus , our data confirm that bub1 regulates sgo1 protein levels but suggest that it does so through a mechanism independent of apc / c . sister - chromatid cohesion is crucial for faithful chromosome segregation in mitosis and meiosis ( 3 ) . sgo1 is required for the protection of centromeric cohesion from prophase to the metaphase - to - anaphase transition until all kinetochores are properly captured by the spindle microtubules ( 7 ) . in this study , we have shown that human sgo1 is degraded in an apc / c - dependent manner during mitotic exit . consistent with our data , xenopus sgo1 is also a substrate of apc / c ( 8) . we have further identified two functional apc / c degrons , a ken box and a d box , in sgo1 . thus , similar to other apc / c substrates , such as securin ( 28 ) , cdc6 ( 29 ) , and nek2a ( 30 ) , sgo1 contains multiple apc / c degrons , which ensure its robust degradation during mitotic exit . figure 9.depletion of bub1 by rnai decreases steady - state levels of sgo1 and sgo1 . log phase , nocodazole ( noc)-treated , or thymidine ( thy)-treated hela tet - on cells stably expressing myc - sgo1 ( left panel ) or myc - sgo1 ( right panel ) were transfected with bub1 sirna for 24 h and analyzed by western blotting with the indicated antibodies . depletion of bub1 by rnai decreases steady - state levels of sgo1 and sgo1 . log phase , nocodazole ( noc)-treated , or thymidine ( thy)-treated hela tet - on cells stably expressing myc - sgo1 ( left panel ) or myc - sgo1 ( right panel ) were transfected with bub1 sirna for 24 h and analyzed by western blotting with the indicated antibodies . sgo1 contains three putative d boxes , but only one d box ( db2 ) is functional . in another study , db3 of human sgo1 we have carefully examined the potential role of db3 in sgo1 degradation . in our experiments , removal of db3 alone or together with the ken box does not stabilize full - length sgo1 in the presence of cdh1 overexpression ( fig . similar results were obtained when db3 was deleted in a c - terminal fragment of sgo1 ( fig . a systematic deletional analysis of the c - terminal region of sgo1 further confirms that db2 is the only functional apc / c degron in this region , and removal of this motif is solely responsible for the stabilization of sgo1c in the presence of cdh1 overexpression ( fig . 2c ) . finally , sgo1c mutants with db3 partially deleted can still be efficiently ubiquitinated by apc / c in an in vitro reconstituted ubiquitination assay ( fig . apc / c regulates orderly progression through mitosis by targeting key mitotic regulators for ubiquitination and degradation ( 16 ) . sgo1 localizes to kinetochores , protects centromeric cohesion during prophase , and prevents premature sister - chromatid separation in mitosis ( 7 ) . in meiosis i , the shugoshin family of proteins also protects centromeric cohesin from cleavage by separase . we had initially envisioned that degradation of sgo1 might be required for its inactivation , thus allowing the timely cleavage of centromeric cohesin by separase at the metaphase - to - anaphase transition . however , expression of a non - degradable mutant of sgo1 in hela cells did not cause a delay in chromosome segregation or mitotic exit . we also did not observe changes in chromosome morphology at different stages of mitosis . these results suggest that degradation of sgo1 itself is not crucial for proper progression through mitosis . additional mechanisms may exist to inactivate sgo1 at the metaphase - to - anaphase transition . alternatively , sgo1 does not prevent the cleavage of centromeric cohesin by separase in mitosis . bub1 regulates sgo1 protein levels in an apc / c - independent mechanism the spindle checkpoint kinase bub1 is required for the maintenance of sgo1 protein levels ( 9 ) . bub1 phosphorylates sgo1 in the vicinity of its apc / c degrons in vitro . recently , it has been shown that cyclin - dependent kinases phosphorylate cdc6 in the vicinity of its apc / c degrons , thus rendering these motifs inaccessible for apc / c recognition and ubiquitination ( 29 ) . this does not appear to be the case , as the levels of the non - degradable sgo1 mutant are still reduced in bub1 rnai cells . our results , thus , suggest that bub1 regulates sgo1 levels through an apc / c - independent mechanism . the centromeric localization of sgo1 depends on bub1 ( 9 , 10 ) . it is possible that sgo1 becomes unstable in bub1-depleted cells because it loses its centromeric localization . on the other hand , bub1 targets pp2a to centromeres , which in turn maintains sgo1 at centromeres by counteracting plk1-mediated chromosome removal of sgo1 ( 12 ) . although sgo1 also loses its centromeric localization in pp2a rnai cells , its protein levels are not reduced in these cells ( 12 ) . therefore , the loss of its centromeric localization per se does not necessarily lead to sgo1 degradation . future experiments are needed to uncover the mechanisms by which bub1 regulates the steady - state levels of sgo1 .

shugoshin 1 ( sgo1 ) protects centromeric sister - chromatid cohesion in early mitosis and , thus , prevents premature sister - chromatid separation . the protein level of sgo1 is regulated during the cell cycle ; it peaks in mitosis and is down - regulated in g1/s . here we show that sgo1 is degraded during the exit from mitosis , and its degradation depends on the anaphase - promoting complex / cyclosome ( apc / c ) . overexpression of cdh1 reduces the protein levels of ectopically expressed sgo1 in human cells . sgo1 is ubiquitinated by apc / c bound to cdh1 ( apc / ccdh1 ) in vitro . we have further identified two functional degradation motifs in sgo1 ; that is , a ken ( lys - glu - asn ) box and a destruction box ( d box ) . although removal of either motif is not sufficient to stabilize sgo1 , sgo1 with both ken box and d box deleted is stable in cells . surprisingly , mitosis progresses normally in the presence of non - degradable sgo1 , indicating that degradation of sgo1 is not required for sister - chromatid separation or mitotic exit . finally , we show that the spindle checkpoint kinase bub1 contributes to the maintenance of sgo1 steady - state protein levels in an apc / c - independent mechanism .

In this photo taken by Alexey Avanesyan, Alexander Kuznetsov, Russian rapper also known as Husky waits for a court hearing in Krasnodar, Russia, Thursday, Nov. 22, 2018. The Russian rapper is facing two... (Associated Press) In this photo taken by Alexey Avanesyan, Alexander Kuznetsov, Russian rapper also known as Husky waits for a court hearing in Krasnodar, Russia, Thursday, Nov. 22, 2018. The Russian rapper is facing two weeks in jail for performing on a car after prosecutors banned his gig for going against the government.... (Associated Press) MOSCOW (AP) — A popular Russian rapper was sentenced Thursday to 12 days in jail for performing on a car after prosecutors banned his gig. Husky, who has a wide following among young Russians with his videos scoring up to 6 million views on YouTube, was arrested Wednesday. A court in the southern city of Krasnodar sentenced Husky on charges of hooliganism. The 25-year-old rapper, known for his songs mocking authorities and police brutality, was due to perform in Krasnodar when local prosecutors warned the venue that his act had elements of what they termed "extremism." Russian authorities have in recent years used the vaguely worded law on extremism to go after Kremlin critics and dissenters. Wednesday's gig was moved to another club, where the power was shut off and Husky's fans poured outside. Videos posted online showed the rapper, whose real name is Dmitry Kuznetsov, reading his verses on top of a car with the fans chanting in unison. Police officers let him finish the song and then detained him, but had trouble driving away as crowds of fans blocked the police vehicle, demanding his release. Police eventually persuaded them to disperse. Local police also said that the owner of the car on which Husky performed filed a complaint for property damage, a charge that may carry a longer prison term. It wasn't immediately clear if authorities were going to press those charges. The rapper told the court that he was forced to perform on the street because his concert had been canceled without explanation. He said he was willing to pay compensation for any damage to the vehicle. "I acted in such a way because I faced a situation when I felt an obligation to talk to the people who had bought tickets," he told the court. Husky's black-and-white videos mock a political regime that expects tacit compliance from its citizens. A new wave of Russian rap musicians is widely credited for channeling young Russians' frustration with the political system and lack of economic prospects. Authorities in other Russian regions have also moved to ban Husky's gigs. Husky said in a social media post last month that officials in several Russian cities are pressuring venues to shut down his shows because his songs allegedly offend Christian believers and promote promiscuity. ___ Vladimir Isachenkov in Moscow contributed to this report. ||||| Rating is available when the video has been rented. This feature is not available right now. Please try again later.

– A popular Russian rapper was sentenced Thursday to 12 days in jail for performing on a car after prosecutors banned his gig. Husky, who has a wide following among young Russians with his videos scoring up to 6 million views on YouTube, was arrested Wednesday. A court in the southern city of Krasnodar sentenced Husky on charges of hooliganism. The 25-year-old rapper, known for his songs mocking authorities and police brutality, was due to perform in Krasnodar when local prosecutors warned the venue that his act had elements of what they termed "extremism." Russian authorities have in recent years used the vaguely worded law on extremism to go after Kremlin critics and dissenters, reports the AP. Wednesday's gig was moved to another club, where the power was shut off and Husky's fans poured outside. Videos posted online showed the rapper, whose real name is Dmitry Kuznetsov, reading his verses on top of a car with the fans chanting in unison. Police officers let him finish the song and then detained him. Local police also said that the owner of the car on which Husky performed filed a complaint for property damage, a charge that may carry a longer prison term. It wasn't immediately clear if authorities were going to press those charges. The rapper told the court that he was forced to perform on the street because his concert had been canceled without explanation. He said he was willing to pay compensation for any damage to the vehicle. "I acted in such a way because I faced a situation when I felt an obligation to talk to the people who had bought tickets," he told the court.

in this century , new changes have resulted in rapid development of service - providing sectors , especially in the health sector ( 1 ) . services provided in different parts of society are considered as the heart of value - creation in the economy ( 2 ) . today , quality of services , especially in institutes with high volume of customers , including financial and care services , has found a great importance in such a way that it could be considered as an essential strategy to achieve the intended results in a competitive market ( 3 ) . quality has been converted into a big challenge to meet expectations of service receivers and their satisfaction ( 4 ) . the problem of lack of quality in providing services occurs in organizations that do not focus on identifying and meeting customers needs and demands . lack of direct relation of organizations with customers finally will result in improper performance and lack of accountability to customers expectations ( 5 ) . evaluating the quality of health services is a prominent scale to measure the amount of realization of health and medical organizations ( 6 ) . it should be noted that customers satisfaction is obtained when organizations that provide health services , such as hospitals , medical centers , and clinics , pay attention to customers expectations as well as their needs and implement required plans to meet customers expectations ( 7 ) . in today s competitive market , promotions are transferred to the society directly by patients or their families , and this issue is very important for medical organizations providing positive experiences for patients and their families and positive perceptions of patients for services received are very important for service - providing organizations ( 8) . the quality of health services generally is recognized as satisfaction of the patients who are referred to medical centers , which have a direct effect on quality and the customers satisfaction . therefore , most medical organizations seek to promote the quality of services to ensure that customers are satisfied with the services they receive ( 9 ) . therefore , providing health care according to patients preferences , expectations , and demands could promote the quality of hospital services ( 10 , 11 ) . expectations are one of the main determinants of customer evaluation of the quality of services , and the main step in providing quality services is accurate identification of customers expectations . in fact , responding to patients expectations is considered as one of the current challenges of the health system , and , in spite of its importance , the identification of patients needs and demands has been neglected ( 12 ) . customers compare their observations of the process of providing services with their expectations of those services , and they judge the quality of the services they receive based on the difference between their expectations and what they actually received . therefore , a quality control strategy is required to reduce these gaps ( 13 ) . the servequal model is one of the most prominent tools to measure customers expectations and perceptions . it is a diagnostic method for introducing weak and strong points of the quality of organizations services ( 14 ) . it measures the following five main dimensions of the quality of services : tangible aspects of service : physical facilities , equipment , appearance of personnel reliability of service provider : performing committed function accurately and reliably responsiveness of service provider : tendency toward helping and responding to customers needs assurance provided by service provider : ability of personnel to induce trust and reliability empathy of service provider with customers : personal attention to customers ( 15 ) . this model has been used in many studies . in their study , safi et al . concluded that quality gaps existed in terms of all five dimensions of the quality of health services in the medical centers north of tehran . the lowest gap , i.e. , 0.68 , was in empathy , and the highest gap , i.e. , 0.88 , was related to physical aspect of services ( 16 ) . in the study by alidoosti on the rural society of shahr - e - kord , the results suggested that health services provided in health providers of rural area are far from favorable , and 37% of the people in the study were weakly satisfied with the services provided ( 17 ) . in a study of private hospitals in malaysia , the findings showed that there was a significant gap between customers perceptions and expectations of provided services that required basic interventions in these hospitals to reduce the gap of service quality ( 18 ) . in the study by padma et al . in the hospitals of india , patients were regarded as main concern of health service providers and hospitals paid special attention to patients perceptions to promote the quality of services ( 19 ) . various studies have been conducted all around the world on the quality of health services . in studies conducted by purcrea ( 20 ) , john ( 21 ) , chakravarty ( 22 ) , zarei ( 23 ) , nekoei - moghadam ( 24 ) , li ( 25 ) , abedi ( 26 ) , xu ( 27 ) , and handayani ( 28 ) , it was specified that there is a negative gap between perceptions and expectations of customers concerning the quality of provided services in health care providing units . it was believed that the need to promote quality of services and paying more attention to individuals in the society were the critical factors for the organizations . garrard and lin , in their studies , evaluated servequal as a proper instrument to measure quality of services and stated that this instrument should be used to identify the gap between perceptions and expectations ( 14 , 29 ) . a study conducted in qazvin province , iran , showed that there was a gap in the quality of health services in this province . however , in this study , the gap distribution was not clear between service providers ( 30 ) . with regard to the gap in quality of services in qazvin province ( 30 ) and the lack of studies conducted to measure the quality of health services in qazvin city , the topic of this study in comprehensive health plans of qazvin province and unified consensus of health exports of qazvin to conduct a study on determination of the study of health services among providers was the main reason to conduct this study . in addition , assuring health services is very important for the health system and people , since they are very critical . evaluating the quality of these services through people s perceptions and expectations therefore , the aim of this study was to investigate the quality of health - providing services according to residents of qazvin province in 2014 . this descriptive study was conducted with residents of qazvin province , iran , in 2014 . a samples size of 400 subjects was selected using the sample size formula and considering the maximum possibility of higher expectations of people compared to their perceptions , p = 0.50 and error coefficient of 5% . by considering cluster effect 2 , , 1,002 subjects were studied for more accuracy . due to the rural population of 25% relative to urban population in qazvin , 253 rural and 749 urban samples were selected . cluster sampling was used and samples were selected randomly from the urban population of qazvin province . the counties of qazvin , takestan , abyek , booyinzahra , avaj , and alborz were investigated . the samples selected from qazvin , abyek , avaj , alborz , boein zahra , and takestan totaled 403 , 51 , 38 , 121 , 44 , and 92 , respectively . the difference between the numbers of urban and rural samples was because of their population ratio with the cities . in addition , among the rural population of abyeh , avaj , alborz , boein zahra , takestan and qazvin villages , 24 , 16 , 21 , 56 , 44 and 82 samples were investigated respectively . this questionnaire included two sections : background variables ( education , age , place of receiving services , waiting time to receive services ) and main questions on five dimensions of service quality ( physical , reliability , responsiveness , assurance , and empathy ) in perceptions and expectations parts . there were four questions each in the physical , reliability , and responsiveness fields and five questions in the assurance and empathy fields . quality of services was calculated using a 5-point likert scale , ranging from strongly agree to strongly disagree . to determine the quality gap , scoring of customers to present situation ( perceptions ) of quality of health services provided was compared with their scoring to desirable status ( expectations ) of quality of health services . if the resulting score were positive , it showed that services provided were higher than peoples expectations and in the case of being negative , it stated that health services provided did not meet peoples expectations , and a quality gap exists . zero score shows the lack of a quality gap , which demonstrates that health services provided are in line with peoples expectations . the place of receiving services was shown as an option in the questionnaire , with six answers , including hospital , clinic , medical center , doctors office , health providers of urban area , and health providers of rural area . in addition , the last place of referring to receive services was regarded as the option to be selected . the validity of the questionnaire was approved by zarei and nekoei - moghadam in iran ( 23 , 24 ) . research tools were selected based on cronbach s alpha score of 0.91 and test - retest method of 0.83 for reliability . data were collected by going to peoples houses in cities and villages and asking questions about the quality of units and health service providers in qazvin province . first , an explanatory workshop was held for interviewers , and its goal was to have experienced local forces of each area collect the data . the ethics committee of qazvin university of medical sciences approved this study with i d number of 8346 . the importance of the study was explained to the participants by interviewers , and the participants were assured that the information they provided would be confidential . a consent form for participating in the study the mean age of the subjects was 32 9.9 , and the average waiting time to receive services was 73 47 minutes . the frequency distribution of the education of the people in the study was 6% illiterate , 34% junior diploma 30% high school diploma , 10% associate diploma , 18% bachelor s degree , and 2% master s degree and higher . the lowest perceptions of the quality of health service providers were related to hospitals , with an average of 3.26 , followed by doctors offices at 3.51 . in addition , the highest perceptions of the quality of health service providing centers was related to health providers of urban area at 3.79 and medical centers at 3.70 ( table 1 ) . the least expectations of people concerning the quality of service providers were related to clinics at 4.49 , and their highest expectations were related to hospitals at 4.68 . respectively , the highest quality gap in health services was related to hospitals and doctors offices with the values of 1.42 and 1.01 , respectively , and the lowest gap was related to health providers of urban area and health providers of rural area with the values of 0.80 and 0.88 , respectively ( table 1 ) . the highest perception of 3.68 was related to junior diploma and the highest expectation of 4.69 was related to master s degree . furthermore , the lowest perception and expectations values of 3.30 and 4.48 were related to those who held associate s diplomas ( table 2 ) . there was a significant relationship between perceptions ( p = 0.000 ) , expectations ( p = 0.01 ) , and quality gap of health services ( p = 0.000 ) with the health service provider . there was a significant relationship between people s perceptions and education ( p = 0.000 ) . however , no significant relationship was observed between quality gap of health services and education ( p = 0.2 ) ( table 3 ) . study of quality gap in all health service providers and comparing them with each other was one of the main issues in this study that has never been found before in other studies and was considered as its strong point . in current study , the highest quality gap of 1.42 in health services was related to hospitals and the lowest quality gap of 0.80 was related to health service providers of health providers of urban area . in a study conducted by jenaabadi et al . in hospitals of zahedan , there was a significant difference in all dimensions of quality between average of perceptions and expectations score . quality gaps in tangibles , reliability , responsiveness , assurance , and empathy were 0.690 , 0.685 , 0.795 , 0.755 , and 0.840 , respectively ( 31 ) . in a study conducted of the hospitals of arak , the quality gap of health services was reported to be 1.20 ( 32 ) , and that complied with the findings of this study . it appears that arak and qazvin are very similar in terms of results because both are industrial cities . in a study by mohammadi on a medical center in zanjan s study , the averages of people s perceptions and expectations for the quality of health services were 3.04 and 4.26 , respectively , and the quality gap was 1.22 ( 33 ) , which complied with the current study in terms of quality gap . the results of a study conducted in khorramabad showed that the quality gap of health services was 0.69 ( 34 ) , which complied with our findings . the results of a study conducted by ghobadi on doctors offices of ardebil revealed a quality gap of 0.65 in health services ( 35 ) . quality gap in doctors offices was higher in qazvin province than in ardebil , which requires reforms and fundamental policy making to reduce this gap . the results of a study conducted by noronesa in fasa revealed that doctors offices need fundamental reforms in terms of meeting patients expectations to promote quality of health services ( 36 ) . in studies conducted by sahebzadeh in isfahan ( 37 ) and azizi in darab ( 38 ) , customers satisfaction with health service providers was not favorable , and that requires policies and plans to promote present situation and move toward favorable status . in studies by butt in malaysia ( 39 ) , rohini in india ( 40 ) , bakar in turkey ( 41 ) , and arasli in cyprus ( 42 ) , there was a negative gap between patients perceptions and expectations in all dimensions of quality of services . in spite of different values of this gap in various studies , it is clear that there is a gap in providing health services all around the world , and fundamental interventions are required to reduce this gap in services . in a study by gorji ( 43 ) and mohammadnia ( 44 ) , negative gaps were observed in quality of health services between customers perceptions and expectations . contrary to all studies conducted in iran , the research society of which was limited , in this study people were investigated in person in all areas of qazvin province by referring to people s houses , which is considered as one of the strong points of this study . in addition , in this study all health service providers , including hospitals , clinics , medical centers , health providers of urban area , doctors offices , and health providers of rural area were compared that have never considered before in other studies . studies by taner ( 45 ) , schrder ( 46 ) , and suki ( 47 ) estimated people s perceptions to be lower than their expectations in terms of quality of health services , which demonstrated a quality gap and lack of meeting expectations of people who were referred to receive health services . in a study conducted in peru , a relationship was found between people s satisfaction with health services and their education and type of services received ( 48 ) . in a study conducted in indonesia , the results showed that trained staff and experienced physicians promote the quality of services and increase satisfaction ( 49 ) . in a study conducted by al - borie in saudi arabia , a significant relationship was found between education and perceptions and satisfaction from the quality of health services ( 50 ) that complied with results of current study . of limitations of this study therefore , it was attempted to use local experts to collect data and investigate all regions as far as possible . the results of this study showed that there was a service quality gap in all health service providers ; however , it was higher in hospitals and doctors offices . since providing human and material resources of health system always involves problems , the practical importance of these findings lies in the fact that weak points could be emphasized more to reduce quality gap in services of hospitals and doctors offices . to reduce quality gap in services , it is suggested that authorities consider customers complaints and deal with them , make essential services available 24 hours a day , promote motivation of staff and physicians to pay more attention to customers , and the staff and physicians should consider the requests and reasonable needs of customers . conducting a complementary study on quality gap of services between state and private sectors in qazvin province with descriptive methodology could be an appropriate path for future studies in this field .

introductionquality is the center of attention in all service providing organizations that are effective in promoting satisfaction of patients who are referred to medical centers . the aim of this study was to investigate the quality of health service providers in a case study of qazvin , iran , in 2014.methodsthis descriptive study was conducted on 1,002 people who were residents of qazvin province ( iran ) in 2014 . the people were selected randomly from the population of the study area . the main variables studied were education , perceptions , expectations , and gaps in service quality . the data collection tool was the standard servequal questionnaire . to determine the reliability of the research tool , we used cronbach s alpha coefficient and the test - retest method . statistical analyses were conducted using spss and the anova test.resultsthe mean age of people included in the study was 32 9.9 years , and the average waiting time to receive services was 73 47 minutes . hospitals and doctors offices had the highest quality gap of 1.420 0.82 and 1.01 0.75 , respectively . the service quality gaps in medical centers , health providers of rural area , and health providers of urban area were 0.883 0.67 , 0.882 0.83 , and 0.804 0.62 , respectively . there was a significant relationship between peoples perceptions and expectations concerning the quality of health services and their educational levels.conclusionthe higher gaps in quality in hospitals and in doctors offices require more attention . managers and policy makers should consider developing and implementing plans to reduce these gaps in quality and to promote better health services in these two sectors .

Story highlights One ruling goes against the government, another supports its position The rulings reignite the fierce political debate over Obamacare For now, nothing changes until the cases completes the legal process The issue would impact those who signed up for Obamacare on the federal exchange It was a tale of two rulings -- the best of times and the worst of times for Obamacare in the federal appeals courts. First, a three-judge panel of the D.C. Circuit court of appeals ruled Tuesday against a key component of the law -- the federal subsidies for millions of people who signed up for health coverage. The 2-1 decision created a legal path for a possible Supreme Court case that could essentially gut the 2010 Affordable Care Act, which passed with zero GOP votes. A few hours later, all three judges on a 4th Circuit panel in Virginia decided the opposite by declaring the subsidies legal and proper. Opposing rulings The opposing rulings increased the chances for the issue to reach the nation's highest court, and demonstrated the deep political divisions over the law despised by conservatives intent on undermining it. Both judges in the majority of the 2-1 D.C. Circuit ruling were appointed by Republican presidents, while all three in the unanimous 4th Circuit panel were appointed by Democratic presidents. Republicans immediately hailed the D.C. panel's ruling against the subsidies as evidence of what they called fatal flaws in the health care law. "This is yet more evidence that Obamacare is not working -- and cannot work -- for the American people," said GOP Sen. Lamar Alexander of Tennessee, who faces a conservative primary challenger questioning his right-wing credentials. At the White House, spokesman Josh Earnest expressed confidence in the administration's legal position, saying Congress clearly intended for all Americans to have access to tax credits if needed so they could afford health insurance. The issue: subsidies The legal argument involves a provision in the health care law that says people who obtained coverage through state-run exchanges can get federal subsidies such as tax credits. It doesn't specifically say that those signing up on the federal exchange also are eligible. Opponents of the law contend that lack of specificity renders illegal the subsidies for anyone who enrolled through the federal exchange. Only 14 states and the District of Columbia set up their own exchanges, meaning that the 4.7 million who signed up for subsidized health coverage through HealthCare.gov could be affected. "It will kill Obamacare," Republican Sen. Orrin Hatch of Utah said of an eventual Supreme Court ruling against the subsidies. "It would make it very difficult for Obamacare to continue because the cost of health care is going to go sky high for those who are not in the state exchange." For now, the law remains unchanged and the subsidized policies are unaffected until the legal case plays out, Earnest told reporters. The Justice Department said the government would appeal the D.C. panel's decision. Partisan divide The easiest fix -- changing the law to specify that it allows subsidies for coverage purchased through the federal government as well as state exchanges -- would mean reopening the debate in Congress. Unlike last time, when Democrats held majorities in both the House and Senate, Republicans now control the House and are expected to make gains in the November election, perhaps taking over the Senate too. That means Obama and Democrats have no chance of getting Congress to approve any remedial change in the law. Sen. Ted Cruz, R-Texas, one of the leading crusaders against the health care act, argued Tuesday that the federal subsidies amounted to assuming funding powers the Constitution granted Congress. Earnest, however, said Congress intended "to ensure that every eligible American who applied for tax credits to make their health insurance more affordable would have access to those tax credits, whether or not the marketplace was operated by federal officials or state officials." Ambiguity The opposing rulings Tuesday pivoted over the meaning of the word "ambiguous." In Richmond, the 4th Circuit judges labeled the Affordable Care Act ambiguous on whether subsidies should be allowed for consumers getting insurance on federal exchanges. When a law is ambiguous, courts give deference to a federal agency's interpretation of the law, which in this case is the Internal Revenue Service rule allowing the subsidies. The D.C. Circuit decision concluded that Obamacare was unambiguous in restricting subsidies to insurance purchased on exchanges "established by the state," rather than the federal exchange. In his dissent, though, appellate Judge Harry Edwards -- a Democratic appointee -- argued that labeling the phrase "established by the state" as unambiguous "strains fruitlessly to show plain meaning when there is none to be found." ||||| WASHINGTON, July 22 (Reuters) - The U.S. Court of Appeals for the Fourth Circuit upheld a federal regulations that implemented subsidies that are vital to President Barack Obama's healthcare overhaul, in direct conflict with another ruling on the issue handed down earlier on Tuesday. A three-judge panel unanimously said the law was ambiguous, and that it would defer to the IRS's determination that subsidies could go to individuals who purchased health insurance on both federal and state-run exchanges. A separate panel from a federal appeals court in Washington on Tuesday morning said the IRS could not offer premium tax credits to people who purchase insurance through the federal insurance marketplace that serves most of the 8 million consumers who have signed up for private coverage for 2014. (Reporting by Aruna Viswanatha) Our Standards: The Thomson Reuters Trust Principles. ||||| A federal appellate court ruling threatens to raise the price of health insurance for millions of Americans who bought through HealthCare.gov. (Theresa Poulson/The Washington Post) A federal appellate court ruling threatens to raise the price of health insurance for millions of Americans who bought through HealthCare.gov. (Theresa Poulson/The Washington Post) A panel of the U.S. Court of Appeals for the District of Columbia Circuit struck down a major part of the federal health-care law Tuesday, ruling that the insurance subsidies that help millions of Americans pay for coverage are illegal in three dozen states. Less than two hours later, a panel of the U.S. Court of Appeals for the 4th Circuit, based in Richmond, handed down a contradictory ruling on the issue in a separate case, raising the possibility of yet another high-stakes battle over the law playing out before the Supreme Court. The conflicting rulings give traction to the most serious current threat to the Affordable Care Act, which has been battered by a series of legal challenges since it was enacted four years ago. The dispute centers on whether the subsidies may be awarded in states that chose not to set up their own insurance marketplaces and instead left the task to the federal government. About 5.4 million people had signed up for coverage on the federal exchange as of this spring, federal figures show. About 87 percent of them received subsidies. The Obama administration said it will ask the full D.C. Circuit court to review the decision in the District case, Halbig v. Burwell. The ruling will not have an immediate effect on consumers, because the judges allowed time for an appeal, and administration officials stressed that people receiving the subsidies will continue to do so as the cases are sorted out in the courts. View Graphic Now, nearly 3.3 million people have enrolled in a health plan between Oct. 1 and Feb. 1. “We feel very strong about the sound legal reasoning of the argument that the administration is making,” White House spokesman Josh Earnest said. “You don’t need a fancy legal degree to understand that Congress intended for every eligible American to have access to tax credits that would lower their health-care costs regardless of whether it was state officials or federal officials who are running the marketplace.” If the decision going against the government it upheld, it will be more damaging to the law than a Supreme Court decision last month that limited coverage of contraceptives. In his dissent, D.C. Circuit Judge Harry T. Edwards noted that the subsidies case went to the core of the law, calling it a “not-so-veiled attempt to gut the Patient Protection and Affordable Care Act.” Conservatives have spent years laying the groundwork for the challenge, which they considered their last, best chance at hollowing out the federal program. Activists had lobbied state legislatures, urging them not to set up their own marketplaces in part to magnify the effect if the courts ruled their way. Four cases have been moving through the courts relying on a similar rationale, among them the D.C. and Richmond cases. The suits argued that Congress intended for the subsidies — in the form of tax credits — to go only to people in states that set up their own insurance exchanges, also referred to as marketplaces. They said they were meant as a “carrot” to entice states to embrace this part of the law. They cited a section of the law that said the subsidies would be available to those “enrolled through an Exchange established by the State.” Lower courts have sided with the government, which contended that Congress meant for the subsidies to be available in all states, including those that left the job of setting up a marketplace to the federal government. It said the intent was obvious from the law’s context, which is why the Internal Revenue Service wrote rules clarifying that the subsidies would be available everywhere. In the 2-to-1 opinion Tuesday in the D.C. case, Circuit Judge Thomas B. Griffith wrote that this interpretation is incorrect. Although the federal government may establish an exchange on behalf of a state, he wrote, “it does not in fact stand in the state’s shoes when doing so.” But in the Richmond case, King v. Burwell, which was decided unanimously by that three-judge panel, 4th Circuit Judge Roger L. Gregory wrote that it is not specified as to whether the subsidies should be available in states that declined to set up marketplaces. Because of this ambiguity, the court concluded that the IRS acted appropriately, and that it is “clear that widely available tax credits are essential to fulfilling the Act’s primary goals and that Congress was aware of their importance when drafting the bill,” Gregory wrote. The D.C. Circuit panel was made up of two judges appointed by a Republican and one by a Democrat. The 4th Circuit panel consisted of two judges appointed by a Democrat and one — Gregory — who was nominated by President Bill Clinton and renominated by President George W. Bush. Supporters of the health-care law predicted that these legal challenges will not succeed. “Today’s decision represents the high-water mark for Affordable Care Act opponents, but the water will recede very quickly,” Ron Pollack, executive director of the consumer health organization Families USA, said in a statement. Republicans, however, cited the decision as more evidence that the legislation is flawed. “Today’s decision rightly holds the Obama administration accountable to the law. The plain text of Obamacare authorizes subsidies only through state exchanges, not the federal exchange,” said Sen. Orrin G. Hatch (Utah), the ranking Republican on the Senate Finance Committee. “The court considered the administration’s justifications and came to an unmistakable conclusion: President Obama overreached.” If the D.C. decision is upheld, it will have wide-ranging consequences for states that declined to set up their own marketplaces. The ruling would affect 27 states, most with Republican leaders who oppose the health-care law, and nine states that partly opted out of setting up marketplaces. Those states are instead being served by the federal marketplace, HealthCare.gov. Legal experts said that under the D.C. ruling, companies in those states would no longer be penalized for not offering their workers health insurance under the employer mandate, which will take effect next year. This is because under the law, employer penalties for not providing health coverage are triggered only when a worker receives a subsidy. Lack of subsidies also would put insurance financially out of reach for the millions of people who are relying on the help this year to pay their premiums. That, in turn, would weaken the law’s requirement that most Americans carry health coverage by increasing the number who qualified for a hardship exemption based on insurance prices. About 9 in 10 people in states relying on the federal marketplace bought health plans with the help of the subsidies. The average tax credit for a person this year is $276, lowering the person’s premium from an average price of $345 per month to an average of $69, federal figures show. If the D.C. Circuit grants the administration’s request for a full “en banc” hearing, legal experts say, the law’s supporters will be more likely to prevail. The court has four relatively new judges nominated by Obama, and the partisan split on the court is now 7 to 4 in favor of those appointed by Democratic presidents. If the full court overturns the panel decision, there will be no split among the circuits. The losers in the 4th Circuit Court’s decision have the same option to ask for a review of the full court. But that court also is now dominated by judges nominated by Democrats, and the challengers may think their chances are better at the Supreme Court and take their appeal there. The question the courts address — how to handle insurance subsidies in the three dozen states relying on the federal marketplace — was one that neither Democrats nor Republicans had anticipated when the Affordable Care Act was written. Even though the measure squeaked through Congress without GOP support, lawmakers and health policy specialists anticipated that virtually all states would create their own insurance exchanges. Exchanges were designed to make coverage more accessible to the minority of Americans who cannot obtain an affordable health plan through a job. The law offered states money to set up marketplaces. And the thinking was that even states with Republican leaders would be eager to run their own marketplaces in the name of state autonomy. So it was a surprise that Republican antipathy to the law proved so intense that three dozen states balked at setting up exchanges, making the federal marketplaces — intended as a lightly used fallback — the main source of new health plans in the country when the exchanges opened for enrollment in October. Robert Barnes and Ann Marimow contributed to this report.

– It's a seesaw day for ObamaCare: One federal appeals court delivered what was seen as potentially devastating news to the health care law today, but hours later a second appeals court came to the opposite conclusion. Both decisions revolve around subsidies for people who signed up for ObamaCare on the federal exchange, as opposed to a state exchange. This morning, a three-judge panel in DC ruled that the federal enrollees aren't eligible for subsidies, which the Washington Post called a "potentially crippling blow" to ObamaCare. Without those subsidies, millions of low- and middle-income people who signed up would likely be unable to afford their premiums. Later, however, a three-judge panel from a federal appeals court in Richmond, Va., ruled in a separate case that subsidies for those on the federal exchange are fine, reports CNN. Or, more specifically, it said that the law's language was murky and thus deferred to the IRS on the matter, reports Reuters. The IRS has previously said that the subsidies can go to people no matter whether they signed up on a federal or state exchange. Expect both decisions to be appealed, with no final resolution likely until the Supreme Court weighs in.

Four to nine factors contributed to each `never event,’ study finds ROCHESTER, Minn. — Why are major surgical errors called “never events?” Because they shouldn’t happen — but do. Mayo Clinic researchers identified 69 never events among 1.5 million invasive procedures performed over five years and detailed why each occurred. Using a system created to investigate military plane crashes, they coded the human behaviors involved to identify any environmental, organizational, job and individual characteristics that led to the never events. Their discovery: 628 human factors contributed to the errors overall, roughly four to nine per event. The study results are published in the journal Surgery. The never events included performing the wrong procedure (24), performing surgery on the wrong site or wrong side of the body (22), putting in the wrong implant (5), or leaving an object in the patient (18). All of the errors analyzed occurred at Mayo; none were fatal. The Mayo Rochester campus rate of never events over the period studied was roughly 1 in every 22,000 procedures. Because of inconsistencies in definitions and reporting requirements, it is hard to find accurate comparison data, but a recent study based upon information in the National Practitioner Data Bank estimated that the rate of such never events in the United States is almost twice that in this report, approximately 1 in 12,000 procedures. MEDIA CONTACT: Sharon Theimer, Mayo Clinic Public Affairs, 507-284-5005, Email: [email protected] Journalist: Sound bites of Dr. Bingener discussing the study are available in the downloads. Nearly two-thirds of the Mayo never events occurred during relatively minor procedures such as anesthetic blocks, line placements, interventional radiology procedures, endoscopy and other skin and soft tissue procedures. Medical teams are highly skilled and motivated, yet preventing never events entirely remains elusive, says senior author Juliane Bingener, M.D., a gastroenterologic surgeon at Mayo Clinic. The finding that factors beyond “cowboy-type” behavior were to blame points to the complexity of preventing never events, she says. “What it tells you is that multiple things have to happen for an error to happen,” Dr. Bingener says. “We need to make sure that the team is vigilant and knows that it is not only OK but is critical that team members alert each other to potential problems. Speaking up and taking advantage of all the team’s capacity to prevent errors is very important, and adding systems approaches as well.” For example, to help prevent surgical sponges from being left in patients, Mayo Clinic installed a sponge-counting system and uses that bar code-scanning system and vigilance by the surgical team to track sponges. Other preventive systems include use of The Joint Commission health care quality organization’s Universal Protocol, team briefings and huddles before a surgery starts, a pause before the first incision is made, and debriefings using a World Health Organization-recommended safety checklist. To investigate the never events, the researchers used human factors analysis, a system first developed to investigate military aviation accidents. They grouped errors into four levels that included dozens of factors: “Preconditions for action,” such as poor hand-offs, distractions, overconfidence, stress, mental fatigue and inadequate communication. This category also includes channeled attention on a single issue: In layman’s terms, focusing so much on a tree that one cannot see the forest. Unsafe actions, such as bending or breaking rules or failing to understand. This category includes perceptual errors such as confirmation bias, in which surgeons or others convinced themselves they were seeing what they thought they should be seeing. Oversight and supervisory factors: Inadequate supervision, staffing deficiencies and planning problems, for example. Organizational influences: Problems with organizational culture or operational processes. In addition to systems approaches and efforts to improve communication, attention should be paid to cognitive capacity, such as team composition, technology interfaces, time pressures and individual fatigue, the researchers say. The stakes are high for patients, physicians and hospitals, Dr. Bingener says. “The most important piece is the patient perspective. You don’t want a patient to have to experience a never event. The breach in trust that happens with that is the most important part,” she says. The study was funded in part by National Institute of Diabetes and Digestive and Kidney Diseases grant K23DK93553. The research team included members of the Mayo Clinic Department of Surgery, the Robert D. and Patricia E. Kern Center for the Science of Health Care Delivery, Quality Management Services and Pulmonary and Critical Care Medicine. Disclosures: Dr. Bingener is supported through an NIDDK research grant, specified research through Nestle and Stryker Endoscopy, has received travel support from Intuitive Surgical, and serves on Titan Medical’s Surgeon Advisory Board. Co-author Susan Hallbeck, Ph.D., receives grant funding from Stryker Endoscopy. ### About Mayo Clinic Mayo Clinic is a nonprofit organization committed to medical research and education, and providing expert, whole-person care to everyone who needs healing. For more information, visit http://www.mayoclinic.org/about-mayo-clinic or http://newsnetwork.mayoclinic.org/. ||||| (Photo: Dmitry Kalinovsky/Shutterstock) You've probably heard about the woman who had a sponge left in her body from a hysterectomy four years ago, or the man whose surgeon accidentally implanted a kidney on his left side, instead of his right. One recent estimate found that catastrophic mistakes—including implanting the wrong thing, or performing the wrong procedure—occur in one out of every 12,000 surgeries in the United States. To figure out why, a team of researchers from the Mayo Clinic in Rochester, Minnesota, decided to analyze botched surgeries at their own clinic in the way investigators do military airplane accidents.* The researchers used an aviation accident-investigation tool called the Human Factors Analysis and Classification System, which helped them pinpoint which human errors are most common in surgeries gone wrong. Their work suggests hospitals should look for ways to reduce the mental lifting that surgery team members must do during a procedure, the researchers write in a paper published last week in the journal Surgery. That's in addition to the "systems engineering"-type of solutions that hospitals have recently used to reduce errors, such as installing computer systems that automatically track surgical sponges' whereabouts—and alert people when sponges get left behind in the body. (Sponges are the most common item left behind after surgeries.) Serious surgical accidents tend to involve many human failures. The average surgery saw nine separate missteps. To conduct the study, Mayo researchers collected Human Factors Analysis and Classification System data from debriefings that surgery teams held after catastrophic mistakes. The HFACS checklist includes 161 human errors, grouped into specific categories, that can happen during a procedure. The researchers categorized the causes of 69 botched surgeries this way. Serious surgical accidents tend to involve many human failures, the researchers found. The average surgery saw nine separate missteps. The most common problems they found fell into the category of the mental conditions of the surgeons and nurses, including overconfidence, and focusing too much on a minute detail and consequently losing sight of the big picture. Another common problem category: "decision errors," like failing to understand the risks of a procedure, or mixing up procedures, tests, and medications that perhaps have similar names. Meanwhile, oversight factors, such as a lack of accountability, and organizational factors—say, a lack of funding—were less likely to be cited as reasons for catastrophic surgery mistakes. The results suggest surgery team members are cognitively overloaded, the researchers write. That's why they're making these mental mistakes. More complicated procedures and technology, and patients with more complicated health problems, all tax surgeons and nurses, other research has found. That can lead people to perform procedures incorrectly, even when they don't intend to. In their paper, the researchers don't offer many specific suggestions for improvement, but they did note that lightening the mental load might involve scheduling fewer procedures for staffers, or giving surgical team members more independence, so they don't have to check everything with one overworked supervisor. Fixing human mistakes in surgery, it turns out, likely means making things easier for the humans involved. Quick Studies is an award-winning series that sheds light on new research and discoveries that change the way we look at the world. *UPDATE — June 15, 2015: This article has been updated to reflect the correct location of the Mayo Clinic.

– To err is human, and deadly when those humans are doctors. Major surgical errors are pretty rare—some estimates put them at one in 12,000 surgeries—but they do happen, even egregious ones like leaving instruments behind or performing the wrong surgery altogether. Mayo Clinic researchers recently set out to find out why by analyzing 69 such events that occurred over the course of 1.5 million invasive surgeries in a five-year period. Reporting in the journal Surgery, they found that "never events" (meaning ones that should never happen) occurred once in every 22,000 surgeries in this window, and that those included 24 wrong surgeries, 22 involving the wrong side or site, 18 instances of leaving an object in the patient, and five wrong implants. The researchers used the Human Factors Analysis and Classification System—initially developed to investigate military aviation accidents—and organized errors into four types, reports the Mayo Clinic: preconditions for action, like overconfidence and inadequate communication; unsafe actions, like breaking rules or confirmation bias; oversight factors, like poor staffing and planning; and organizational influences, such as problems with operational processes. They found that most major errors involve an average of nine missteps, and that mental states of doctors and nurses (e.g., overconfidence and stress) were the most common source of errors, reports Pacific Standard. And while they didn't get specific on how to mitigate these errors, they did note that lightening the workload should ease the error rate. (Hospitals appear to profit from these mistakes.)

SECTION 1. SHORT TITLE. This Act may be cited as the ``Community Disaster Loan Equity Act of 2005''. SEC. 2. FINDINGS. Congress finds the following: (1) Major disasters, including natural disasters and disasters caused by terrorist acts, often result in a decline in economic activity in areas affected by the disaster and a reduction in tax collections by State and local governments serving those areas. (2) A report of the Government Accountability Office entitled ``September 11: Recent Estimates of Fiscal Impact of 2001 Terrorist Attack on New York'', dated March 2005, confirmed prior estimates that-- (A) New York City lost between $2,500,000,000 and $2,900,000,000 in tax revenues for fiscal years 2002 and 2003; and (B) the State of New York lost $2,900,000,000 for fiscal years 2002 and 2003. (3) The impact of Hurricane Katrina on State and local tax revenues is not yet known, but the impact is believed to be extensive. (4) Under the community disaster loan program (in this section referred to as the ``CDL program''), as authorized by the Robert T. Stafford Disaster Relief and Emergency Assistance Act, the President may make loans to a local government suffering a substantial loss of tax and other revenues as a result of a major disaster, if the local government demonstrates a need for financial assistance in order to preform its governmental function. (5) The President may cancel the repayment of all or any part of a loan made to a local government under the CDL program if revenues following the disaster are insufficient to meet the operating budget of that local government as a result of disaster-related revenue losses and additional unreimbursed disaster-related municipal operating expenses. In the case of a major disaster designated as an incident of national significance, including natural disasters and disasters caused by terrorist acts, repayment of any interest or principal on a loan made under the CDL program should not be required. (6) Assistance made available under the CDL program is often instrumental in aiding the full recovery of a local government following a major disaster. (7) The Disaster Mitigation Act of 2000 established a $5,000,000 limitation on loans made to a local government under the CDL program in connection with a major disaster. Before the date of enactment of such Act, there was not any limitation on the amount of such loans. (8) The $5,000,000 limitation is inequitable when applied to a local government serving a largely populated area, such as New York City, and when applied to an area that is completely devastated by a major disaster (such as Orleans, St. Bernard, and Plaquemines parishes in the State of Louisiana following Hurricane Katrina), and is inconsistent with the objective of the CDL program to provide meaningful assistance to a local government recovering from a major disaster. (9) On October 4, 2005, the Mayor of New Orleans announced that the city was laying off 3,000 city employees as a result of reduced tax revenues following Hurricane Katrina. SEC. 3. COMMUNITY DISASTER LOANS. (a) Eligibility of States.--Section 417 of the Robert T. Stafford Disaster Relief and Emergency Assistance Act (42 U.S.C. 5184) is amended by striking ``local government'' each place it appears and inserting ``State or local government''. (b) Amount.--Section 417(b) of such Act (42 U.S.C. 5184(b)) is amended-- (1) by striking ``based on need, shall'' and inserting ``based on need and shall''; and (2) by striking ``, and shall not exceed $5,000,000''. (c) Incidents of National Significance.--Section 417 of such Act (42 U.S.C. 5184) is amended by adding at the end the following: ``(e) Incidents of National Significance.-- ``(1) Loan terms.--In the case a loan made under this section to a State or local government which may suffer a substantial loss of tax and other revenues as a result of a major disaster that the President determines to be an incident of national significance-- ``(A) the amount of the loan shall not be subject to the per centum limitation in subsection (b); and ``(B) the President shall not require the payment of any interest or principal on a loan. ``(2) Incident of national significance defined.--In this subsection, the term `incident of national significance' has the meaning such term has in the national response plan established pursuant to section 502(6) of the Homeland Security Act of 2002 (6 U.S.C. 312(6)).''. (d) Applicability.--The amendments made by this section shall apply with respect to any major disaster occurring on or after August 24, 2005.

Community Disaster Loan Equity Act of 2005 - Amends the Robert T. Stafford Disaster Relief and Emergency Assistance Act to authorize the President to make community disaster loans to state governments. Eliminates the $5 million limit on such a loan, and prohibits the President from requiring its repayment, if the state or local government receiving it may suffer a substantial loss of tax and other revenues as a result of a major disaster determined to be an incident of national significance. Applies this Act to any major disaster occurring on or after August 24, 2005.

antibiotic stewardship programs improve patient outcomes and cost - effectiveness in critically ill patients in the icu . the infectious disease society of america ( idsa ) and the society for health care epidemiology of america ( shea ) published guidelines for antimicrobial stewardship in 2007 aimed at providing information on how to establish such programs within health care institutions . because antibiotics are used heavily in the icu antimicrobial stewardship is broadly defined as a practice that ensures the optimal selection , dose and duration of antimicrobials and leads to the best clinical outcome for the treatment or prevention of infection while producing the fewest possible side effects and the lowest risk for subsequent resistance . antimicrobial stewardship programs may contain a variety of interventions that are complementary to effective infection prevention and control programs . inappropriate antimicrobial usage is a significant problem , with approximately 50% of antimicrobial usage being unnecessary or suboptimal in hospital , community or ambulatory settings . a recent study showed that approximately 20% of patients admitted to the icu with clostridium difficile - associated diarrhoea were receiving antibiotics without any obvious evidence of infection , with an accompanying 28% in - hospital mortality . as a consequence of indiscriminate antibiotic use , there are reported increases in the incidence of infections caused by resistant organisms . a significant correlation was demonstrated between the increase in fluoroquinolone prescriptions in canada from 0.8 to 5.5 per 100 persons per year and increased ciprofloxacin - resistant streptococcus pneumoniae from 0% to 1.7% . twelve percent of patients previously exposed to piperacillin - tazobactam were colonized with strains of enterobacteriaceae resistant to this antibiotic and the use of third generation cephalosporins is associated with higher rates of vancomycin - resistant enterococci and extended - spectrum -lactamase - producing organisms . anti microbial resistance emerging in response to the selective pressure exerted by antibiotics is also a clinical phenomenon , with outbreaks of antibiotic - resistant pseudomonas aeuroginosa and acinetobacter baumanii - calcoaceticus occurring in icus , where a huge antimicrobial pressure is present [ 9 - 11 ] . although they are often life - saving , antibiotics can also cause serious harm to patients , including clostridium difficile - associated diarrhoea , antibiotic - resistant infections and invasive candidiasis [ 12 - 14 ] . antibiotics also result in dangerous drug interactions , life - threatening hypersensitivity reactions , nephrotoxicity , and qt prolongation , to name a few . inappropriate antibiotic use also contributes to rising drug and hospitalisation costs , and the need to preserve our current antibiotic arsenal has assumed greater importance with the paucity of new antibiotic development . clinicians have long been aware of the risks of antibiotic resistance associated with inappropriate antibiotic use , but nonetheless very few effective antibiotic policies have been implemented , and the problem appears to be even worsening . the costs associated with antibiotic usage are also escalating , with systemic antibiotics being the single most costly drug class over the past decade in non - federal hospitals in the united states . in 2007 , systemic antibiotics accounted for 11.2% of the pharmacy budget of non - federal hospitals . in addition to direct pharmacy costs , hospitalisation and other infrastructure costs are also increased , ultimately resulting in a greater strain on the healthcare system . saving antibiotics will save money , and there are a variety of methods to do so . education is the cornerstone of any antibiotic stewardship program , with prescriber education and implementation of guidelines and clinical pathways improving antimicrobial prescribing behaviour . for example , studies using algorithms to shorten the course of antimicrobial therapy in ventilator - associated pneumonia led to significantly lower antimicrobial therapy usage with reduction in costs , antimicrobial resistance , and super - infections without adversely affecting the length of stay or mortality . the absence of formal antimicrobial stewardship training programs for infectious diseases fellows , board - certified physicians , and pharmacists has recently been a challenge to the education imperative , however . preauthorisation ( also known as formulary restriction ) requires approval by a pharmacist or physician prior to clinical use of an antimicrobial . although preauthorization is thought to be the most effective method of controlling antimicrobial use , it does not alter the duration of therapy or the decision to give or withhold antibiotics . the main benefits of this strategy are the supervision of antibiotic use by experts and substantial cost savings ( with some studies demonstrating cost savings upwards of us$800,000 ) . through prospective audit with interaction and feedback , antimicrobial use is reviewed after antimicrobial therapy has been initiated and recommendations are made with regard to their appropriateness in terms of selection , dose , route and duration . prospective audit with feedback avoids delays in initiation of therapy and maintenance of prescribers ' autonomy , and can be implemented in health care facilities of varying sizes . a large teaching hospital reported a 37% reduction in the number of days of unnecessary antibiotics use by decreasing the duration of treatment and by reducing new starts . in another study , antimicrobial suggestions from an infectious disease fellow and a clinical pharmacist resulted in 1.6 fewer days of parenteral therapy and cost savings with no adverse effects on clinical response . another study demonstrated a sustained decrease in parenteral antibiotics over a 7-year period following introduction of a prospective audit with interaction and feedback . multiple studies using healthcare information technology , such as computer - assisted decision support designed to provide treatment recommendations , have shown significant reductions in the use of antibiotics and greater de - escalation to narrow - spectrum antimicrobials . improvements in cost and efficiency of existing stewardship programs , and improved physician knowledge regarding treatment and pathogen prediction were also noted [ 27 - 29 ] . in addition to improving antimicrobial use and patient care ( including tracking of antibiotic resistance patterns ) , such systems can improve surveillance of hospital - acquired infections and adverse drug events when compared to manual surveillance methods . in a 15-month study using a web - based antimicrobial approval system linked to national antibiotic guidelines , a sustained reduction in third - generation cephalosporin prescriptions these benefits have also been noted in an icu - based study , where investigators used computerised anti - infective programs and were able to document significant reductions in the use of excessive drug dosage , adverse drug events and length of hospital stay and costs . standardized pre - printed or computer - generated physician order sets can improve the efficiency of antibiotic stewardship programs . in a study looking into their benefits in the management of patients with septic shock in an emergency department , order sets were found to improve initial fluid resuscitation , use of appropriate antibiotics and 28-day mortality . a recent study to evaluate the hospital - wide impact of a standardized order set for the management of severe bacteraemic sepsis has shown that a greater number of patients received appropriate initial antibiotic therapy with decreased incidence of organ failure and improved survival . a survey of 670 us hospitals found that implementation of guideline - recommended practices to control antimicrobial use and optimize the duration of empirical therapy was associated with less antimicrobial resistance , including methicillin - resistant staphylococcus aureus , vancomycin - resistant enterococci , fluoroquinolone - resistant escherichia coli and ceftazidime - resistant klebsiella species . given the relationship between antimicrobial use and antimicrobial resistance , antimicrobial stewardship appears to be a logical first step in the effort to control antimicrobial resistance . the efficacy of antimicrobial stewardship programs has been the subject of a recent cochrane systematic review , examining 66 studies from 1980 to 2003 . the main interventions analyzed in the review were targeted to decrease treatment ( 57 studies ) , increase treatment ( 6 studies ) or both ( 3 studies ) . the interventions addressed the antibiotic regimen ( 61 studies ) , the duration of treatment ( 10 studies ) , the timing of first dose ( 6 studies ) , or the decision to prescribe antibiotics ( 1 study ) . optimization of antibiotic use was seen in 81% of the studies aimed at improving antimicrobial utilization . significant improvements in microbiological outcome ( for example , prevalence of antibiotic - resistant bacteria ) and clinical outcomes ( for example , mortality and length of hospital stay ) were also noted in some studies . recent observational studies ( subsequent to the cochrane review ) have demonstrated that reducing antimicrobial pressure correlates with improved antimicrobial susceptibility of pathogens . antimicrobial stewardship programs using the methods described above will promote the optimal use of antimicrobial therapy , leading to the best clinical outcome for patients . the relative paucity of outcome data demonstrating the benefits of antimicrobial stewardship is likely due to its infancy : antimicrobial stewardship programs today are where infection control programs were roughly 30 years ago . because antimicrobials are widely prescribed in the icu , with an apparent mortality benefit with appropriate therapy , using the best available methods to optimize their use through antimicrobial stewardship despite the publication of guidelines for improving the use of antimicrobial agents in the united states , a great deal of scepticism about the effectiveness and acceptability of antimicrobial stewardship programs persists . in a survey conducted by the united states centers for disease control and prevention 's national nosocomial infections surveillance systems , only 40% of selected hospitals had antibiotic restriction policies and 60% used stop orders . antimicrobial stewardship programs are also 50% less likely to be implemented in community hospitals compared to academic hospitals . two years after the publication of the idsa / shea antibiotic stewardship guidelines only 48% of survey respondents stated that their hospital had a program . reduction in the incidence of bacterial resistance is touted as the main advantage of antimicrobial stewardship programs , but lacks scientific evidence to support it . in a recent survey of 33 us hospitals , there was no significant correlation between antibiotic guideline adherence by physicians and resistance rates . antibiotic use in icus may be the consequence rather than the cause of resistance , and there is a risk that stewardship , with its emphasis on decreased antibiotic use , could lead to a substantial increase in patient risk . it is also important to note that neither the published guidelines nor the important stewardship articles identify safety as an endpoint . another potentially adverse consequence of antibiotic restriction is the emergence of new resistance patterns replacing the old ones . a study documenting the introduction of new guidelines that restricted cephalosporin use was primarily aimed at reducing the incidence of cephalosporin - resistant klebsiella spp . even though the primary aim was achieved , this occurred at the expense of increased imipenem usage with the subsequent increase in incidence of imipenem - resistant p. aeuroginosa by about 69% . thus , formulary restriction does not necessarily prevent the potential overuse of available broad spectrum antibiotics in routine practice . rather , a significant change in clinical thinking to reduce our dependence on and abuse of antibiotics is needed . antimicrobial stewardship programs form only one strategy for minimizing the incidence of resistance , and must partner with infection control measures , including surveillance , outbreak investigation , disinfection and sterilization , and environmental hygiene . of the studies reported to be beneficial , it remains unclear as to whether the reported improvements in resistance rates are related to antimicrobial stewardship programs , infection control measures or both . although healthcare information technology is believed to be a key component of antimicrobial stewardship programs , detailed information on the resources required to implement and maintain these sophisticated computer programs is not widely available . it is also not clear whether the reported cost - effectiveness of many of these stewardship programs takes into account the overall cost of these interventions above and beyond the pharmacy - related costs and expenses associated with development and distribution of educational materials . another challenge to implementing antimicrobial stewardship in the icu deals with the confidence intensivists have in the clinical judgement of the stewardship physician . a junior physician might be a less effective antimicrobial stewardship team member because of a perceived or real lack of knowledge and experience , but may be utilized because the ' price is right ' . in the survey by pope and colleagues , personnel shortages ( 55% ) , financial considerations ( 36% ) , and resistance from administration ( 14% ) were frequent barriers to establishing antimicrobial stewardship programs . opposition from prescribing physicians was a barrier to establishing an antimicrobial stewardship program in about 27% of cases . while antimicrobial stewardship programs have rather consistently shown significant improvement in antimicrobial utilization , there are very few studies examining meaningful clinical outcome measures such as duration of hospitalization , mortality rates , or even quality indicators such as patient satisfaction . in the systematic review by the cochrane collaboration on antibiotic stewardship programs , clinical outcomes such as mortality and length of hospital stay were reported in only 15% of the studies . in the 2008 survey by pope and colleagues , also , none of the studies report any significant reduction in antimicrobial side effects as a result of these interventions . hospitals are increasingly implementing antimicrobial stewardship programs in response to increasing antimicrobial resistance ( despite aggressive infection control practices ) , coupled with fewer novel antimicrobials and increasing antimicrobial costs . there is little question that antimicrobial use is causally related to antimicrobial resistance , and there is growing evidence that stewardship measures aimed at optimizing antimicrobial use can reduce antimicrobial resistance while reducing associated costs . being major foci of antimicrobial resistance and the largest consumers of antimicrobials in most hospitals , icus can expect to benefit most from antimicrobial stewardship programs . full implementation of antibiotic stewardship programs requires significant investment , however . in the present economic climate , barriers to implementing such programs include personnel shortages , financial cut backs , and resistance from administration who are reluctant to assume economic risk . focusing on patient safety initiatives and the benefits of cost savings and cost avoidance may enable hospital administrators to look upon antibiotic stewardship programs favourably . supplemental strategies such as consultations provided by specialists in infectious diseases might also be used in lieu of clinical decision support systems . such expertise has been shown to improve antimicrobial use , shorten duration of mechanical ventilation and icu stay , and to reduce in - hospital and icu mortality , although it is unlikely that a clinical - decision support system would be entirely replaced . in addition to pre - authorization and/or audit - and - feedback approaches , icus should consider other strategies to improve antimicrobial utilization . in short , stewardship programs should be adapted according to the individual needs of institutions , but should be adequately resourced to achieve their intended aims . icus are complicated systems , and implementing a complex program into another complex structure raises the potential of unintended ( and often unmeasured ) adverse consequences . all icus should have an antimicrobial stewardship program accompanied by a system to monitor clinically meaningful outcomes such as mortality and length of stay . monitoring such outcomes presents an excellent opportunity for infection control and other patient quality and safety initiatives , whose aims include prevention of healthcare - associated infections and control of antibiotic - resistant organisms . in the absence of such monitoring , antimicrobial stewardship programs are nothing more than programs to reduce antimicrobial use with a largely unproven effect on patient care . close collaboration between critical care , infectious disease , infection control , medical informatics , microbiology , and pharmacy staff are needed for the success of an antimicrobial stewardship program . from our experience , leadership and a culture that embraces change is critical to implementation of a successful antimicrobial stewardship program . idsa : infectious diseases society of america ; shea : society for healthcare epidemiology of america . amm is director of the antimicrobial stewardship program at mount sinai hospital and university health network in toronto .

you are director of a large multi - disciplinary icu . you have recently read that hospital - wide antibiotic stewardship programs have the potential to improve the quality and safety of care , and to reduce the emergence of multi - drug resistant organisms and overall costs . you are considering starting one of these programs in your icu , but are concerned about the associated infrastructure costs . you are debating whether it is worth bringing the concept forward to your hospital 's administration to consider investing in .