If a policy is epsilon-greedy, is it technically stochastic?

Question: Even though if exploration doesn't happen, it's deterministic.
Comment: I found this is the book "Intro to RL": " In general, policies may be stochastic, specifying
probabilities for each action." So, according to the book, it is not, but I was supposed to use a stochastic policy in n-step Sarsa, instead, I used epsilon-greedy, and the algorithm still learns.
Comment: I am not sure I understand the purpose of this question. Are you asking "how much stochasticity there must be in a policy in order to be considered a stochastic policy?" How do you want to measure that? Or are you asking whether a policy that sometimes is not stochastic should be considered stochastic or not? It's a matter of convention, but I would say that it makes more sense to consider this policy stochastic (because it's sometimes stochastic) than deterministic (because it's not always deterministic). Maybe you can classify policies into classes of stochasticity.
Comment: My point is - If you define determinism as a "[view where all events are determined completely by previously existing causes](https://en.wikipedia.org/wiki/Determinism)", then $\epsilon$-greedy is not deterministic, so it must be the opposite? It may also be worth pointing out that we could consider $\epsilon$-greedy actually an infinite set of policies, where at one extreme you may have something that is completely random, at at the other extreme you have something that is completely deterministic.
Answer: I would argue it is just stochastic because it chooses the current best action with probability $1-\epsilon+\epsilon/|A|$ and then selects randomly among the rest of the actions with the remaining probability $\epsilon/|A|$, where $A$ is the action space. The current best action is updated over time with running averages and may be the same one in the long run if it is truly a stationary bandit environment, but it will still explore.
Comment: Technically it selects the current best action with probability $1 - \epsilon + \epsilon / \vert A \vert$. In the case where we select actions uniformly at random (with probability $\epsilon$), one of the options is generally again that we randomly select the best action :)
Comment: oops thanks, will revise
Comment: @DennisSoemers, can you explain how you got the ϵ/|A| part?
Comment: @Melanol With probability $\epsilon$, we sample one action uniformly at random from a set of $\vert A \vert$ actions. Sampling "uniformly at random" means we assign equal probabilities to all those actions, which means that each of those actions (including the "best" one) gets a probability of $1 / \vert A \vert$. That gets multiplied by $\epsilon$ because the whole sampling-uniformly-at-random thing only happens with probability $\epsilon$
Answer: Yes - you can think of an epsilon-greedy policy as a mixture of a policy that chooses an action at random (the stochastic part) and a possibly deterministic policy used otherwise. The value of epsilon gives the weight of the random component, and $1-\epsilon$ that of the other component.
Answer: When a policy is stochastic, it means taking actions will be done based on probabilities. For example, in deterministic policy (in the case of navigation for four actions), if an agent takes upward action, it will go up and etc. However, in stochastic policy, if an agent takes upward, it may go up with 80% of probability and go right with 20% of possibility. Thus, in epsilon-greedy based policies, we choose actions in exploration mode randomly, but it does not mean it is stochastic.
I tried to explain short and clear.


Does Vietnam allow concurrent passports?

Question: In other words, can one have two Vietnamese passports at the same time?
Answer: Since I dont really understand your question, I assume that there are two cases for this:
Case 1: If you mean to ask whether or not you can use two passports to enter Vietnam (i.e one is Vietnamese passport and the other is US passport), you CAN TOTALLY USE one of them to enter the country. If you choose to use Vietnamese passport, you must follow the regulations of Vietnam government. The same goes for US passport that you must also follow US government's regulations.
Case 2: If you mean to ask whether or not you can use two Vietnamese passports at the same time (literally described in your question above), then the answer is No. You cannot have two valid passports at the same time. Vietnam's government does not allow this to happen. If you apply for a new passport, the old one will be invalid right at the time you get a new one.
Note: If you use one passport for entry and the other for exit from Vietnam, then it is illegal according to Vietnam laws.
Comment: Hi, welcome to Travel.SE! Most of us here believe the most useful answers are those that can be substantiated with references - can you please add link(s) and quote(s) that supports what you claimed?
Comment: Re: case 1, this is a common misconception: you are definitely bound by Vietnamese law even if you enter with a US passport.


Is there a way to intuitively understand this?

Question: The growth in an exponential growth system can be described by:
$y = i\cdot(1+\frac{r}{n})^{tn}$ . I want to prove that the overall rate of growth $r$ despite being divided by the number of times compounded ($n$), is still the same ($r$) when applied the power $n$. It doesn't seem right that NET exponential growth rate should change regardless of how many times we compound the system. For example, if I have a 100 percent interest rate and it is compounded once annually: $y = i\cdot(1+(1/1))^1 \cdot 1 = i \cdot 2$. I want to show that if we do 50 percent interest semi-annually, the rate of growth over a full year is still 100 percent. If its true of course.
Comment: It's not true; that is the whole point of compound interest. $1.5^2=2.25$, which is better than 100% annually.
Answer: Your guess is incorrect: you are looking at what people call compound growth.
If you had \$1 and received 100% interest in a year, you would expect to have \$2 by the end of the year. However, if you had 50% compounded twice a year, you would earn an additional 50% interest on the \$0.50 that you received at mid year (hence the term 'compound interest', where you earn interest on interest), so you would finish with \$2.25.
Thus compounding the system indeed increases the growth rate, but there's a limit to this: as you compound more frequently (say every second), the most you can have by the end of the year is about \$2.72. This number is called $e$, and one way we define this in mathematics is the limit as $n$ goes to infinity of $\left(1+\frac{1}{n}\right)^n$.
Comment: Is there any way to model a system where you can have 50 percent growth rate twice and end up with the original amount using the exponential growth formula?
Comment: What do you mean by the 'original amount'? If you're saying 100%, and using compound interest of 50%, then the answer is of course not: the formula gives you what it gives. To get a 100% return through paying a 50% interest rate twice, you would have to be doing a principal-only interest, where you pay interest on the initial \$1 only. This is equivalent to calculating the interest you would pay in a year (\$1) and distributing it evenly over the number of payments to make (e.g. $\frac{\$1}{2} = \$0.50$ twice in a year).
Comment: I meant original growth rate of 100 percent. Ok, that makes more sense. Also is there a reason why r is divided by the number of times compounded, it could just as easily be divided any other amount of times. Is there any significance in dividing r evenly over all the time intervals?
Comment: @A.AK The reason to take $\frac rn$ is in order to have the same growth rate during the first $\frac1n$ as you would have without compounding for the same $\frac1n$ of a year. Also, this way you will end up with the same interest $r$ on the principal - everything else will be compound and compound on compound and ...
Answer: You are looking at the difference of $$1+na$$ and $$(1+a)^n=1+na+\frac{n(n-1)}2a^2+\dots+\binom nk a^k+\dots+a^n.$$
As $a=\frac rn$ is positive, the second binomial sum has more positive terms than the first, and is thus larger. The only way to get equality is for $a=0$, that is with no growth rate at all.


can you make textures in magicavoxel?

Question: I'm working on a project that allows the player to purchase different skins. Can you make textures in MagicaVoxel? If not what are some good programs to make textures? I aiming to make blocky 3d textures for the skins that I can turn into a material to manipulate in Unity.
Answer: Magica Voxel exports to .fbx and .obj with a single long strip texture image, and has a general Atlas-like UV unwrap which applies that strip of colours to the geometry.
It's kinda... dumb... texturing as it's a PIA to work with elsewhere.
However, it should be pretty easy to work with in Unity, if the intent is to keep a similar feel there to what you set up in Magica Voxel. I've not tried it in Unity yet, though I spend a fair amount of time working in Unity - so I'll hafta try it and see how it does.
Of note: the polys themselves don't have independent material tags on them - they're all one material, and it's the position of the colour block on the strip and the relevant UV alignment that determines colour: you can, I'm sure, use the free Pro Builder tools to re-material-tag polys as you see fit in Unity, but bear in mind that will be a wholly manual process.
One plus of the one long strip texture image approach is that creating new variant skins shouldn't be terribly difficult!
Hope that helps some.

can you make textures in magicavoxel?


I would like to be able to use some tokens like %post[key]used in webform, in my custum module how to call these up in my custum module

Question: I am creating a custom module webform3rdparty integration to icontact .Using my module create an extra field in weform field to add icontact field(mapping purpose).I want to use token replacement patterns in my field.How to call these replacepatterns in my custom module.
Answer: I think you need these hooks:

hook_token_info() - this hook will allow you to define empty placeholders. Define a few placeholders which you want to make available to the webform.
hook_tokens() - corresponding to the plkaceholders you have defined, pass in appropriate stuff and define a replacement pattern for each placeholders you have defined in your earlier hook_implementation.
Finally, while rendering user submitted value, apply token_replace() function to replace the placeholders entered by user with appropriate values.

UPDATE:
Got you. Have a look at this function _webform_filter_values(). This funciton is responsible for replacement of webform tokens. you can use this funciton in your code, pass in the stuffs you want to replace and the node and submiccions object and have the value replaced.
It will be impossible for me to give you exact direction, as i am not familiar with what you are doing. But i can give you a general idea. Token replacement often happens at the output stage. So it is more concerned with output. So mostly, you need to apply this to your code which displays/prints/uses the webform submission result of your field.
Say you create a webform field. I as an end user, enter a string to it which contains this: %post[key]. Now your submit handler code will need to use the said function. When you pass the input i entered through that function, my %post[key] is replaced by appropriate value.
Comment: I want to call replacepatterns used in webforms in my site.ie,I would like to be able to use  tokens %post[key]
Comment: Updated my answer. please have a look.
Comment: Thank you neo for your detailed reply.But still i am confused how to implement for that particular field created by my module.
Comment: I will not be able to provide you with detailed code, but just updated my answer as the last shot to help you grab the concept. hope that helps.


what is this error in PSPICE with IR2113

Question: I want drive a buck converter with bootstrap technique. but this circuit does not work!
Comment: Did you edit this to be a completely different controller now? Looks nothing like the circuit I initially based my answer on. And the PSPICE error is missing?
Comment: Try putting an earth on the negative end of V4 and see what happens. At the moment it looks floating to me and I don't think it would properly work if you built it without that cross-connection to the driver.
Comment: The error is telling you the step size is too small. Fix it.
Answer: The IR2118 doesn't seem to be hooked up correctly. Its floating high-side bootstrap pin (VB) isn't actually connected to anything -- it should be hooked up to at the least a capacitor to the VS pin, and the application diagram calls for an external diode connecting VCC to that node as well:

Right now, it has no ability to generate the boosted drive voltage for your transistor because the bootstrap supply isn't working / isn't connected correctly. Since you are using a N-channel enhancement mode device, it requires a positive VGS to function. The IR2118 driver has a floating pin (VB) which supplies the positive voltage to the MOSFET, referenced against whatever the source of the transistor is connected too:

In the typical connection diagram, thanks to the diode between VCC and VB, it's creating a simple voltage multiplier to generate the voltage needed to drive the transistor. You could also hook up some arbitrary high-voltage supply to VB.


The Equivalence Principle – Why Objects Fall at the Same Rate

Question: I'm having a debate with my father. He says that it is perfectly understandable why objects fall with gravity at the same rate despite being of differing masses. His point is, in relation to the mass and gravitational pull of the Earth the difference between a feather and a cannon ball's mass relative to the mass of the earth is negligible. Therefore gravity acts on them in the same way (or very nearly almost the same way). Is he right?
Comment: Related: http://physics.stackexchange.com/q/11321/2451 and links therein.
Answer: The mass of the earth actually does not define which of the two bodies (feather or cannon ball) falls first. The problem is a bit more deep that that, and it is actually the reason behind General Relativity and in general, all geometric formulations of gravity.
Roughly speaking, the way masses move is solely dependent on the local properties of the gravitational field, independently of their mass. This observation lead Einstein to the formulation of the Equivalence Principle, and is the reason we think of gravitational force as a reflection of the local curvature of space time.
If you're familiar with a bit of math, if $m_{\rm grav}$ is the gravitational mass of a body (measure how much it is affected by gravity) and $m_{\rm inertial}$ is its inertial mass (measure how difficult is to change its state of motion), then Newton's second law states that when this body is the presence of a mass $M$ its acceleration follows the expression
$$
m_{\rm inertial}a = G\frac{m_{\rm grav}M}{r^2}
$$
This provide a way of measuring the ratio in the lab
$$
\frac{m_{\rm inertial}}{m_{\rm grav}} = \frac{GM}{ar^2}
$$
The result is that this number is one with an accuracy of 1 in 20 million. So we are tempted to believed that indeed inertial mass is the same a gravitational mass and consequently, that all masses are affected the same way by gravity, or said in other words, that gravity is an emergent property of the local geometry of spacetime.
Answer: No, he is not right. The reason is that the gravitational mass of an object is equal to its inertial mass. For all we know this is exact and there is no approximation involved besides the assumption of no air resistance.
In more detail: The gravitational "pull" force with which the earth (of mass $M$) pulls on an object of (gravitational) mass $m_g$ at a distance $r$ from the center of earth, is given by:
$$F=\frac{GMm_g}{r^2}$$
As you can see, this force depends on the mass of the object and will be much bigger for the cannon ball than for the feather. Just put a cannon ball on your head and you will feel the difference compared to having a feather on your head.
According to Newton's law this force causes the object to accelerate with acceleration:
$$a=\frac{F}{m_i}$$
where $m_i$ is the inertial mass, which you can imagine as a resistance to acceleration.
Making use of the fact that $m_g=m_i$, you find from these two equations that the acceleration is independent of the object's mass and only depends on the distance from earth:
$$a=\frac{GM}{r^2}$$ which on the surface of earth ($r$ equal to earth radius) is the familiar acceleration $g\approx 9.81~m/s^2$.

Or in words:

Earth pulls stronger (larger force) on heavier objects
Heavier objects are harder to move (require more force to accelerate)

Miraculously, for reasons unknown, it turns out that these two effects just cancel each other such that the acceleration is the same for heavier and lighter objects.
Answer: Yes, he's right.  The gravity well of the earth is significantly greater than both that of the feather and the cannon ball. As such, they travel along nearly identical geodesics at nearly identical rate.


Problem creating boot option for USB

Question: I have a bootable USB stick with Ubuntu 13.10, but my ASUS g74 laptop doesn't have a boot option for USB.  I can create one, but it asks for a path.  The drive is the G drive, is it then /boot/grub?  what am I missing?
Answer: To install Ubuntu from a USB drive, you should:

Plug your USB Drive
Boot your computer

Then your computer should automatically show a welcome screen prompting you to choose your language and giving you the option to either install Ubuntu or try Ubuntu from the USB.
ELSE you might need to change the device from which the computer starts up to the USB.
You can usually do this by watching for a message appearing when your computer starts to boot:

You should be invited to change the boot device. Once you've selected that option, follow the instructions on screen.
Or you have to press F12 or Escape while your computer is starting up to change your boot device order.

Depending on your computer and how your USB key was formatted, you should see an entry for removable drive or USB media. Move this to the top of the list to force the computer to start from USB rather than the hard disk. Save your changes and continue.
Info from Install Ubuntu

Problem creating boot option for USB


When forming an enzyme-substrate complex in a spontaneous reaction, why does free energy increase?

Question:
We eat food and which is digested into proteins and carbohydrates.
Does digestion break bonds within food macro molecules and decreases free energy? Why, when looking at curve, do we see an increase in the free energy and then a decrease?
Comment: This increase is the activation energy: https://en.wikipedia.org/wiki/Activation_energy
Answer: Kinetics and thermodynamics are two separate things. The type of diagram you show is often encountered (even in textbooks) because it is thought to be a convenient hand-weaving way to convey a feeling of what is happening. However it is not correct as it mixes two different views: the microscopic molecular view (horizontal axis) and the macroscopic thermodynamic view (vertical axis).
The result is a misleading idea that the (molar?) Gibbs free energy (of what ???) can go up (event temporarily) along a spontaneous reaction. However for a spontaneous process (and "spontaneous" is key here) the Gibbs free energy of a system can never increase.
What can increase is the potential energy of a molecular system of the reacting molecules along a reaction path, which is what the vertical axis should represent. In which case the graph would represent a potential-energy profile. But defining a thermodynamic property like a molar Gibbs free energy for a single molecular entity has no meaning.
One might argue that considered as a chemical species, the transition state at the top of the curve (generally called the "activated complex") is obviously unstable and, considered collectively (i.e. macroscopically) must have a higher molar Gibbs free energy (at any specific time during the reaction). However, this is only partially true: it has a higher molar Gibbs free than the product towards which the flux of matter goes, but it necessarily has a lower molar Gibbs free energy than the reactants that are consumed (else the reactants would never form the said activated complex). Also, at the end of the reaction, when equilibrium is reached, all species have equal molar Gibbs free energy so that the Gibbs free energy of reaction is null ($\Delta_r G = 0$).
An alternative, really thermodynamic diagram is sometimes represented: the Gibbs energy diagram. In such diagram, the Gibbs energy of the successive species might appear to go up and down. But one should be careful of the impression given because such diagrams actually represent the standard Gibbs energies of the reactants, which is not their Gibbs free energy in any arbitrary state, and especially not necessarily their Gibbs free energy in the condition of the reaction considered.


Direct Phone Connection / Network Port over WAN

Question: We have two office buildings connected by a WAN. Our primary office has a phone system that requires each handset to be connected to the PBX via cable (it is NOT VOIP compatible). We are setting up some offices in the second building but don't want to upgrade our phone system and I was hoping to find some way of 'mapping' a network connection over the WAN? This might be completely impossible (I'm a novice doing my best to help out with some tech stuff) but along with the server/internet traffic travelling across the WAN I want to send data from the phone port across the WAN and have it sent to the phone handset once received (please excuse lack of jargon).
If I can clarify further please ask as I don't really know how to explain what I want.
Thank you very much!
Comment: I'm pretty sure that can't be done. Before VoIP, you usually had to have a phone system ("switch") in each building which you could then connect with trunk lines if you wanted campus dialing. You could double check that there is no VoIP add on card or module for your phone system, there might even be third party solutions.
Answer: Look into Asterisk (http://www.asterisk.org  - free software-based PBX, heavy on VOIP).  It's possible to use a COTS computer with a PCI line card to pair with a PBX.  You configure your PBX to see Asterisk as a partner system and to treat the terminal/port connecting to the line card as an outbound trunk.
At that point you can use VOIP from the Asterisk side to "bridge" your WAN connections.  Possible to use ATA's (Analog Telephone Adapter) on the far end to connect "regular" telephones to the Asterisk PBX.  You can also/instead connect VOIP phones fairly easily if you have them.  (or use software-based phones -- anything supporting SIP will probably "work," but as always your mileage will vary)
This will require some customization in Asterisk and some finagling and it will not work perfectly seamlessly but it IS a solution that would allow you to bridge your phone system across the WAN with a minimum of expense.
Also an important consideration is QoS on your network.  Newer Cisco switches can use the AutoQos feature to set this up fairly painlessly.  Your WAN QoS scenario will also be a factor.
Answer: Your phone system is not VoIP. It cannot be directly bridged by IP. (every digital PBX I know of, does this by installing a VoIP module, and even there, it's a proprietary bridge between two PBX's)
If the PBX is pure POTS, then a channel bank (T1) and some circuit emulation trickery could get that T1 carried across an IP network. But such a hackish solution is a waste of time and money -- even if this stuff is in a box under your desk.
Answer: If your phone system supports extenders over T1 or the two phone systems can be linked by T1 in some fashion, you could look into using something like the Cisco NM-CEM-4TE1 module.
I was in an environment where they had an older Avaya system and wanted to install an extender at a remote location.  We used Cisco routers with this module at the time which allowed the Avaya PBX to "hand off" a T1 to the routers  which then encapsulated it as IP traffic to provide a T1 to the extender at the remote location over the WAN link.
You may have to do some research as it has been awhile and some of the hardware may be end of life at the point, but there should be something similar.


How can I keep my freshly baked loaf fresh until the next morning if I bake it at night?

Question: I wwould like my bread to be fresh the next day when I bake it at night but I know you shouldn't cover your freshly baked bread as it will soften it. Can I leave it on the counter uncovered overnight? Will it still be fresh?
Comment: Depends how you define "fresh". I don't have access to my books right now, but IIRC, the first type of starch retrogradation occurs after one hour, the second starts after a day. So there is probably no way at all to have the "just-baked" softness after more than an hour. Generations of bakers working night shifts to sell fresh loaves at 6:00 AM are another argument for that, if there was a way, they'd have found it by now. As for best keeping, try leaving it in a woven cotton bag on the counter, a non-breathing cover will fog and dampen it.
Comment: @rumtscho- I'm not putting an answer because it would have been what you just said. This should be an answer not a comment.
Comment: I am sensing a "Michael Scott Morning Bacon" situation here.
Comment: So-called "artisan" breads and sourdough can be left out for days without significant loss of moisture, even after cutting, but I presume you are talking about a standard white bread.
Answer: It may be a matter of how you are defining 'Fresh', but my experience has been that 'fresh' isn't that hard to maintain, as long as I'm making a loaf with a significant crust; just don't cut it.  I tend to leave the bread on the rack in my oven overnight to cool down, with no loss of freshness, as long as it hasn't been cut into.  Once it's cut into, things change, but the crust itself isn't terribly vulnerable to getting stale quickly, and protects the rest of the bread.
Answer: When I lived in South America we would put our bread on a paper bag and that would maintain it fresh. :)
Answer: Roll it in a damp cloth, it might help you to keep it fresh.
Comment: It strikes me as this would be likely to turn it soggy and/or grow mold, but I haven't tried it.
Comment: Might? Have you tried this?


Joint PDF of sample mean and variance

Question: Assume $Y$ is a r.v. which follows a normal distribution with mean $\mu$ and variance $\sigma^2$. How could we find the probability density function of $\overline{Y}$ and $\sum_{i=1}^n \frac{(Y_i-\overline{Y})^2}{\sigma^2}$? I know that the sample mean follows a normal distribution and the sample variance follows a chi-square distribution and both are independent. Therefore we can just multiply the marginal density functions. But my question is, how could we get this from the joint density function of the n observations of $Y$? i.e. computing the integral.
Answer: Given the joint density $f_Y (y_1, \dots, y_n)$ you should be able to apply the Jacobian transformation method to find the joint density of $Y_1, \dots Y_{n-2}, \bar{Y}, \frac{\sum (Y_i - \bar{Y})^2}{ \sigma^2}.$
One can then find the joint density of just $\bar{Y}, \frac{\sum (Y_i - \bar{Y})^2}{ \sigma^2}$ by integrating this joint density over the supports of $Y_1, \dots, Y_{n-2}$.

Joint PDF of sample mean and variance


Construct an Asp.Net auto-complete name picker

Question: Here we go: Your typical absolutely web newbie question. :-)
How to build such Asp.Net name picker where I can collect a few names from a textbox separated by semicolons and then, after validation of some sort, mark those valid names in black underscore and invalid ones in red underscore. You know it's a little like the SharePoint name picker behavior.
I know jQuery and Ajax.Net already provide useful AutoComplete controls but I don't know how to enable the underscore style on top of those controls.
Hey btw I just noticed the 'Tags' textbox of posting question page here is pretty darn close to what I want so anyone knows how it's done?
Answer: Maybe you can use something like this http://loopj.com/jquery-tokeninput/demo.html
Good luck!


wysiwyg missing on Campaign description

Question: Strangely, We have a wysiwyg for the campaigns goal field on New/Edit Campaign form but not description field. Is that intentional? Our users are not high tech and are not familiar with HTML tags. Is it an easy thing to enable on description field?
Answer: You should have the wysiwyg on campaign description field after installing Convert textare to WYSIWYG extension
HTH
Pradeep
Comment: Unfortunately the extension isn't in the list inside your CiviCRM install. And many folks will only install those on the extensions page.
Comment: Agreed, There are lots of extensions which sits on their individual/Organization git/gitlab/bitbucket account because they were never meant to release under Civi Extension. If there is a request to have this available as part of Civi Extension I am happy to do that. Its users choice if they want to use extension from Civi extension page and/or from other repos
Comment: Yes, it's best to do it that way, as then people are more comfortable with it. Plus it makes it easier for folks to install.

wysiwyg missing on Campaign description


adding bass to an amplifier

Question: How does one add bass to an audio amplifier? Assuming we have a basic pre amplifier and power amplifier in hand, and we have an ordinary speaker at the load. Do we need to buy another specialized speaker for bass since last time I went to an electronics store, they sell tweeters.
Comment: vvavepacket, you really need to go pick up a book on this material. Your fundamental understanding of many of the topics you ask about is way off. We want to help you, but we aren't your private tutoring service.
Comment: You can't make whipping cream with a toothpick. If you speakers attenuate bass response and unable to pump the air with displacement, pressure and clarity, no amp will help.
Answer: For a traditional bass and treble control circuit, look up "Baxandall tone control" online or in Horowitz and Hill.
Answer: You say you want to add bass to the amplifier and then mention speakers. Do you want better response in your entire sound system? When we talk about the amplifier, we are only talking about the power amp and possibly the pre-amp. The speaker is a separate entity.
When we want to add bass to the signal, generally some form of equalization is used before the power amplifier stage. If you want to add bass response to your speaker, you will generally either use a better speaker (usually larger with a better enclosure and better materials), or you can add specialized speakers for each frequency range. Many speakers have multiple drivers in a single device, like this studio monitor:

Notice the smaller and bigger speaker. These speakers separate the frequencies using an internal audio crossover and play certain frequencies from the appropriate driver. If you want you can buy separate sub-woofers for your music, which will play only the lowest frequencies. Depending on the system you use you may need to make a crossover yourself.
Please go get a book on some of this material and try to cement your fundamentals. For the audio specifically, I like Thompson's Understanding Audio. For the circuits, I learned on Sedra and Smith, but there are tons of good books out there. You can learn all this stuff independently if you put your mind to it. Good luck!
Answer: Usually you have an "equalizer", which is a set of adjustable filters between the preamp and the power stage, and a "crossover", which is a set of filters between the output and the bass/treble speakers.
Generally the larger the speaker, the better the frequency response at low frequencies. Designing speaker enclosures for best response is an art in itself.

adding bass to an amplifier


Resonance vs flutter

Question: Is there any difference between resonance and flutter. Both of them are related to overlap of external excitation frequency and Natural frequency then increase in amplitude even inifite amplitude theorytically.
What is the difference between them?
Answer: In flutter, the force applied to the structure depends on the deformation and velocity of the structure. Therefore, the force is necessarily at exactly the same frequency as the motion, though it may not be at the correct phase to cause the motion to increase in amplitude.
Often, flutter is caused by the structure having two different vibration modes with similar (but not identical) frequencies, and the flutter occurs at a frequency which is not equal to either of the mode frequencies.
In resonance, in frequency of the force is not necessarily the same as the natural frequency of the structure, and the amplitude of the response depends how close the two frequencies are to each other (and also on the amount of damping the system, of course).
Comment: It should be noted that the actual vibration frequency is always identical to the excitation frequency in *both* flutter and normal resonance. Flutter is a fluid dynamics problem.
Answer: I think flutter is when self excitation happens and there may not be any external vibration. Flutter mostly happens in aviation on airfoils such as wing-tips, ailerons , empennage, and because of self excitation it can grow in intensity to dangerous catastrophic levels even in smooth air.
Airplane manufacturers design their planes in the wind tunnel to eliminate flutter under design operational envelop, even at failure of some sections.
Resonance is when the external excitation frequency is close to that of the natural frequency of the object and causes the vibration amplitude and energy to increase and even become very high if excitation frequency matches that of natural frequency.
Answer: Ok, you have a system of some kind. Normally, (not resonance, and not flutter),  you apply a force, you get a displacement. e.g. for sake of argument let's just say application of 10 N force gets 0.1 m displacement.
Now, at resonance, you can apply a small force and get a large displacement.  e.g. 10 N force gets 10 m displacment.  That's 100X the normal relationship, a big amplification.
Now, at flutter, what happens is that the displacement itself causes the size of the force to change.  e.g. there's an intial 0.01m displacement.  that displacement, in and of itself, causes a force of 0.1N.  The force then causes a larger displacement, 0.1m, which then causes a larger force 1N, when then causes a larger displacement 1m, etc, etc, etc.  Both the force and displacement grow exponentially until something happens to stop it.
Answer: In the flutter, actually, we have a new system with different dynamic behavior, namely the frequency, damping, and also the mode shapes are changed. In the flutter, the source of vibration is a disturbance and the system fulls on a self-excitation.
For example in an aeroelastic flutter, the frequency and damping of the wing change as the airplanes speed changes and are different from its structural natural frequencies on the ground.
But in the resonance, the system is not changing and the external effect (force) causes an osmolarity motion or deformation. the source of vibration, in this case, is a harmonic external force with one of the natural frequencies of the system.

Resonance vs flutter


Fatal Error PHP, Pear?

Question: I started with this questions:
Fixing PHP PEAR error
And I went with what was suggested, but that does not appear to work.
My code now looks like this:
require 'DB.php';
require 'C:\Users\Clayton\Desktop\formhelpers.php';

$db = DB::connect('mysql://root:password@localhost/test');
if (DB::isError($db)) { die("connection error: " . $db->getMessage( )); }
$db->setErrorHandling(PEAR_ERROR_DIE);

//create table for responses
$q = $db->query(
"CREATE TABLE apiResponse(
 Name VARCHAR(20),
 Occupation VARCHAR(20)");

//select data to send
$db = DB::connect('mysql://root:password@localhost/test');
$q = $db->query('SELECT Name, Occupation FROM try2 ');
while ($row = $q->fetchRow())
{
    $Name = $row[0];
    $Occupation = $row[1];

   $q = $db->query(
   "INSERT INTO apiResponse (Name, Occupation) values ($Name, $Occupation)"
);

Where require 'C:\Users\Desktop\formhelpers.php'; is line 10.
I still get a similar error:
Warning: require(C:\Users\Desktop\formhelpers.php) [function.require]: failed to
open stream: No such file or directory in C:\xampp\htdocs\myfiles\Testing API
Script.php on line 10

Fatal error: require() [function.require]: Failed opening required
'C:\Users\Clayton\Desktop\formhelpers.php'
(include_path='.;C:\xampp\php\PEAR') in
C:\xampp\htdocs\myfiles\Testing API Script.php on line 10

Because the directory did not solve the problem I'm thinking my previous questions about editing the PEAR file  may be relevant.
My questions:
The file that needs to be corrected is the php.ini file in xamp? (I previously downloaded php straight from php.net)
I have both a php.ini for development and for production... which one do I edit?
The .ini file opens in notepad, I'm not sure this is the correct place to edit it. Confirmation?
Comment: You running this in a browser via http requests? The web server userID is unlikely to have access to your desktop folder. make sure that ENTIRE path is readable by the webserver's account.
Comment: It seems strange to me that the warning and the fatal error are failing to open different required files...
Comment: I'm using xamp if that helps Marc B
Answer: $q = $db->query(
"CREATE TABLE apiResponse(
 Name VARCHAR(20),
 Occupation VARCHAR(20)");

there is missing the last parenthesis.
$q = $db->query(
"CREATE TABLE apiResponse(
 Name VARCHAR(20),
 Occupation VARCHAR(20))");

Comment: The final while block is also missing a trailing `}`.  but that may have just been accidentally truncated in the copy+paste shuffle.

Fatal Error PHP, Pear?


Physical interpretation of nodes in quantum mechanics

Question: In Schrödinger's approach to quantum mechanics, we talk about the probability of finding a particle in a definite location in space. Now if we look at a simple quantum mechanical system, say the behaviour of  particle in harmonic oscillator potential, we see that there are nodes, indicating that the probability of finding the particle at those points is zero, indicating that the particle cannot be at that place. This does not make sense to me physically. So I was wandering what can be so special about that point in space that the particle cannot be there?
Comment: Zero probability events can and do happen. Unity probability events might not occur. The technical nomenclature is "almost never" and "almost certainly", respectively.
Answer: I would not say that the probability of finding a particle in a node is zero. While technically that statement may be correct, it does not make much sense, as the probability of finding a particle in any other point is also zero. It would be more precise to say that the probability density is zero at a node. As for why the probability density in a node vanishes... Well, this is just a consequence of the Schroedinger equation, and the main (if not the only) reason we use this equation is that it correctly describes experimental data. You can use comparisons with the nodes of mechanical standing waves, but I am not sure such a comparison, while useful, explains much.
Comment: The comparison is useful inasmuch as one understands the solutions to the Schrodinger equation to be generalized standing waves.
Comment: @ZeroTheHero : I agree that the comparison is useful and I said as much in my answer. Let me just add that solutions of the Schroedinger equations can describe running waves as well, not just standing waves.
Answer: This is analogous to the nodes in a plucked guitar string or an organ pipe.
For simplicity let's consider an infinite 1D potential well rather than the quadratic potential of the simple harmonic oscillator. In the well, where the potential is zero, the solutions to the wavefunctions are plane waves, and the plane waves can travel in both directions. When we impose the boundary conditions we find superpositions of the left and right going plane waves give use the well known eigenstates of the particle in the well.

(Image from Wikipedia)
This is mathematically exactly the same as the standing waves we get from plucking a guitar string or when generating pressure waves in a pipe such as an organ pipe. The nodes are caused by interference of the left and right going waves.
Note that the interference does not remove the particle, it just pushes the particle around. That is it makes the particle more likely to be found in some places and less likely to be found at the nodes. The total probability of finding the particle remains unity.
Comment: OP wants a physical understanding. What's vibrating in the case of a particle in a box? Why, physically, are there points where we never find the particle?
Comment: The Schrodinger equation is a non-relativistic approximation.  The Dirac equation includes spin and relativity and eliminates the points of zero probability density.  Nodes still exist for Dirac solutions, however, the probability density is a sum of contributions from both the large and small component solutions and I've never seen a situation where nodes in both the large and small components occur at the same spatial point.


How to trigger autohotkey script with a download

Question: I want to trigger my script every time my Gpodder program downloads an MP3.
Answer: I would modularize the script for this. So you could have your main script run in a loop (code below) to check for a .mp3 file in a directory you have set "Gpodder" to download to, and then fire another .ahk file with the script you have in mind.
The following script will check every 60 seconds in F:\Directory\Path\to\Gpodder\Downloads\ for any .mp3 file (note the wildcard). When one is found, it will run the script at F:\Path\to\Second_Script.ahk
F2::
Loop, F:\Directory\Path\to\Gpodder\Downloads\*.mp3
{
Run, F:\Path\to\Second_Script.ahk
Sleep, 5000 ; Sleep 60 seconds
}
return


How to account for games and number of teams in share of points?

Question: I am doing research on the relationship of income inequality on team performance in soccer. The team performance I measure through share of points, so the number of points a team got in a particular season, divided by total points earned by all teams. However, I have data on multiple years, and in each year, the number of teams in the competition differs, and also at a particular moment, the number of matches played differs. Of course, this has impact on the share of points. When there are more teams in the competition, it is logical that all shares will be lower, than when having fewer teams. How can I account for this? I guess it will affect my model.
Answer: If you simply divide the total points earned for one team divided by the total points for all teams, it will be unfair to teams that have good defense and are able to win low-scoring games. So, I think your performance index you created is the performance of only the offense.
Also, a team's goal is not to score as many points as possible and prevent the other team from scoring as much as possible. The goal is to win. Therefore, the most straight forward approach is to calculate the percentage of games won in the regular season in each year (not counting playoffs because only some teams play).
If you really want to take the scores into account, maybe, for every game, subtract points scored by the other team from the points scored, and average across all games in that season.
You may also consider multivariate approaches that take all those as variables as indicators of a latent variable called performance.
Comment: Hi, I think you get me wrong. In soccer, when you win you get 3 points, a tie 1 point, lose 0 points. So in the end, team with most points will be the champion. By points, I do not mean the goals scored. Since there can be a tie, I think winning percentage is not a good measure.
Comment: I see. But what justifies that a win is 3 times the worth of a tie?
Comment: I don't know. That's just the system. It is clear that the team with most points in the end is the overall winner. So I think this is a good measure of performance. When using winning percentage, how do you account for a tie? It can be treated as half a win (to make sure the overall winning percentage would be still 0.5 as required), but I don't feel like that is the right way to do it.


Wave Interference (Control Tower vs Mobile Phones)

Question: I was curious about something regarding radio waves. When we're talking about differences of 200 MHz between waves, is there any way of any noticeable interference occurring? By noticeable I mean noticeable in a practical sense. I want to know if mobile phones can interfere with control towers when on a plane, from my research till now the frequencies can't get any closer than 200 MHz
Comment: Mobile phones use an ultra-wideband transmission scheme which had different implication for "interference" than you might expect if you are thinking in terms of constructive/destructive interference of coherent signals.
Comment: @dmckee what do you mean by "ultra-wideband transmission scheme"?
Comment: @hyportnexit would appear that I have confused my terminology. That should read "spread-spectrum" though the point that the technology creates and responds to interference differently than coherent transmission remains.
Answer: Whether 200MHz frequency difference between two signals matters or not depends on the power ratio of the signals in the "victim" receiver and the method of the detection in it.
High level interference in a receiver can cause all kinds surprising problems related to the nonlinearities in the receiver chain, primarily generated in the front-end amplifier and mixer but also further down the chain. These non-linearities can create a plethora of inter-modulation and cross-modulation products, etc., various spurious signals, "spurs" and "intermods" are the buzzwords, that are very difficult to control and filter. Some signals are more sensitive to these inter-modulation products than others, broadly speaking the wider the spectral bandwidth relative to that of the intermods the easier is their removal, but again there are no general rules.


GUI Builder for Blackberry Java Plug-in for Eclipse

Question: From searching online, I learnt that until July 2010, Blackberry Java Plug-in for Eclipse did not include a GUI Builder. RIM releases an update version 1.3 on Dec 23 2010. Is it the same case now? or Does The BlackBerry Java Plug-in for Eclipse v1.3 includes any kind of a GUI builder tool?
Answer: The current plugin page doesn't mention the inclusion of a GUI builder. It would be pretty big news if it did, as the lack of a visual layout editor is one of the biggest complaints about BlackBerry development.
Answer: Apparently, RIM have cancelled it, based on the forum post "Visual UI Designer Plug-in for Eclipse"


If lightning is caused by ionisation of air, why does it only last briefly?

Question: I'm comparing lightning and fire - both are related to ionisation of air but lightning happens so fast in a blink of an eye while fire goes on until it runs out of fuel. My question is: despite being plasma just like a fire, why does lightning only occur for such a brief time?
Comment: Do you know what is "fueling" a lightning strike as compared to what is fueling a fire?
Comment: What's ionized in fire?
Comment: @Felicia Some of the molecules and atoms in the flame? The hotter the better, but the flame chemistry in "hydrocarbon" fires appears to lead to more ionization than one would ordinarily expect, see https://link.springer.com/chapter/10.1007/978-1-4684-1938-2_8
Comment: Ain't ya glad it doesn't last ;-).
Comment: Also, yes, ionization is "related" to both, but the cause-effect direction is opposite.
Answer: Lightning is an electrostatic discharge. After that phenomenon,  the atmosphere and ground temporarily neutralize themselves. Hence, it is over in a blink of an eye.
Fire is a byproduct of some chemical reaction and hence can go on for a longer time.
https://www.quora.com/Scientifically-speaking-is-there-any-connection-between-fire-and-lightning
Comment: @MikeM I don't think so, it seems to intended as "not permanent" i.e. the discharge will neutralize the potential difference for a moment but as soon as the lightning ends the electric potential difference will again start to increase.
Comment: is "temporarily" intended as a word like "quickly" ?
Answer: Fire is a chemical reaction fueled by some product that undergoes combustion, generating energy by breaking (usually) carbon chain molecules down into $CO_{2}$ and $H_{2}O$.  So long as fuel plus oxygen is available and no extinguishing forces are present, the fire will continue to burn.  Lightning, in contrast, requires an electrostatic discharge to breakdown the neutral particles into an ionized gas.  This results from a very large electric field.  Once discharged, the electric field energy is gone so there is nothing to continue to sustain the lightning pulse (i.e., flow of current).
Ionization, dissociation, and recombination all occur on extremely fast time scales in an atmosphere with number densities pushing ~$10^{19} \ cm^{-3}$.  Fire is, at best, a VERY weakly ionized, dusty plasma (e.g., see discussion at https://physics.stackexchange.com/a/340276/59023).
As noted at https://physics.stackexchange.com/a/288810/59023, the recombination time is proportional to $\propto \sqrt{ \tfrac{ T_{e} }{ n_{e}^{2} } }$, where $T_{e}$ is the electron temperature and $n_{e}$ is the electron number density.  The value for $n_{e}$ in a lightning discharge is on the order of ~$10^{17}--10^{18} \ cm^{-3}$ and the temperature is ~0.7-4.3 eV, which means the recombination time scales are going to be tiny (i.e., slowest I would expect would be microseconds or less).
Comment: @TLW - Fair point and thanks for the dissertation.  This is neat stuff...
Comment: It's instructive to look at spark gap equations. The time to 90% breakdown voltage recovery is typically on the order of a millisecond. Pretty quick, but still nowhere near the microsecond range. (I _think_ the discrepancy is because of reaction times for atoms to reform molecules, but I am not a chemist.)
Comment: @TLW - The current pulse recovery time scale is on the order of 15 $\mu$s according to [Thomas et al. [2008]](https://doi.org/10.1029/2008JA013567).  The recombination time scale is just derived from things like the thermal speed and plasma frequency.
Comment: Ok, but saying 'component X recovers in microseconds' doesn't affect my statement that there are components that recover in the millisecond range. (See e.g. https://ttu-ir.tdl.org/bitstream/handle/2346/13998/31295004439542.pdf?sequence=1&isAllowed=y )
Answer: For the fire the source of energy is the "chemical" energy stored in the reacting compounds whereas for lightning the stored of energy is electrostatic in nature due to the separation of charges.
Comparing power, gas fire - $4\times 10^3$ watts and lightning strike - $3\times 10^8$ volts and $3\times 10^4$ amps $\Rightarrow \approx 10^{13}$ watts, you will note that the rate at which energy is dissipated in a lightning strike is much, much greater than that in a gas fire.
Thus one would expect the lightning strike to last for a much shorter period of time than that for a chemical fire.

@Peter-ReinstateMonica has made a valid comment that I only compared powers so here is an analysis resulting in a time for the event answer.
A gas stove has a power rating of about $4\,\rm kW$ and suppose that it is run from a cylinder of propane which contains $10\,\rm kg$ of gas with a calorific value of $50\,\rm MJ\,kg^{-1}$.
So if run continuously the cylinder will last about one day.
The paper Measurement of the electrical properties of a thundercloud through muon imaging by the GRAPES-3 experiment has some estimates on page 4 regarding thunderclouds.
There is an estimate of $\ge 720 \,\rm GJ$ stored at a potential of approximately $1\,\rm GV$.
Taking the figure for the current during a lightning strike to be $30\,\rm kA$ gives an estimated time for a complete discharge (which is unlikely) of the cloud to be $\mathbf 20\, \rm ms$.
Comment: Well, the amount of energy converted in a lightning is still "striking", and the time either phenomenon lasts depends on the amount of energy available, divided by the power. In order to make that calculation you'd have to make estimates about the energy stored in the ionized atmosphere (and in combustible materials, which is comparatively well known).
Comment: As an example, the Sun has a higher power rating than lightning but still lasts much longer as a phenomenon due to the large amount of nuclear energy available. I'm very thankful for both sides of the comparison [insert praise of our goldilocks universe here].
Comment: @Peter-ReinstateMonica  I have taken note of your comments and included  an **estimate** of the time scales.
Comment: Wow, I love it! 720GJ, cool.
Answer: Imagine looking at a fire, let's say a candle flame. There is a region with partially ionised gas at the edge of the visible flame in the lower part of the flame. Think about the gas in that spot. It is a mixture of air from the surroundings and evaporated wax that came from the wick, undergoing chemical reactions that heat it up. The crucial issue is that the gas is not at rest, but moving upwards through the flame at significant speed.
Where were the gas molecules that are reacting with each other in the flame right this instant a fraction of a second before? Some of them were in the surrounding air, being drawn toward the flame, and some were inside the wick in the form of liquid wax which then evaporated. And a fraction of a second later, they will be rising up above the flame and no longer emitting noticable amounts of light.
The atoms and molecules which are ionised at any given time are so only for a short interval of time. The gas inside the part of the flame where there is significant ionisation is constantly moving and gas which moves out of this zone is being replaced by other gas moving inside it. This means that the duration of the ionisation is also quite short in the case of the flame – when you look at it from the point of view of the gas molecules – similar to the lightning case.
The difference is that in the case of lightning, the whole gas volume is ionised almost at once, then it recombines and the process is over, whereas in the case of a flame it's a steady-state process with fresh reactants moving into the flame and reaction products moving out continuously, but the duration of ionisation of individual molecules is also short, as explained in the answer by honeste_vivere.
Comment: All you say is true; but how is it related to the duration of the phenomenon, and how is it different from lightning?
Comment: @peter added clarification
Answer: Like many (if not the majority) of question posters on this site you proceed from a false premise. Lightning is not caused by the ionization of air. It is caused by polarization of static charges at the bottom of the cloud and the ground. Lightning does not even need air to propagate through, or any medium for that matter. Although the discharge is a result of dielectric breakdown of the air within the potential of the charge difference, a vacuum also has a dielectric constant which can be easily overcome by the large voltages generated by the static polarization of these charges.


Article classification

Question: I am stuck with the idea of developing a deep learning model to find news updates for specific topic let's say invention in "autonomous driving". I have some articles labeled by experts. (label relevant/not relevant). I would like to have a contentwise similarity score for new articles on the web.
Comment: So what is your question?
Comment: He doesn't know where to start.
Answer: NLP is rather quite hyper-dimensional. I'd go data-driven way and use some pretrained embedder. Nowadays there're a few to choose from, like LASER from Facebook. There's unofficial pypi lib, though it works just fine. If you want to reach seminal-like scores, there's no point in doing NLP by hand. Embedders usually cover dozens of languages, so you can feed training data in any language you want. Your models will also work for those languages out-of-the-box, even if you trained them on other languages. If you need some custom stuff, you could pick BERT from Google, though you'll have to push it yourself further. It isn't really pretrained that much.
Comment: Thank you very much.I will try using LASER

Article classification


Blocked by Content Security Policy when visiting icloud.com with firefox

Question: does anybody know why I'm getting the following issue when visiting icloud.com with firefox. I've tried disabling all add-ons and protection, but still it didn't work.
Answer: Just found out it's the following setting that's preventing icloud.com from loading:
After all it's caused by an add-on. I thought I already tested with all add-ons disabled, perhaps I didn't.
Answer: I recommend you disable this protection per site by clicking on the 3 vertical dots and unchecking "Spoof Referer header" instead of globally as your answer suggests. A great thank you for pointing me in the right direction.


No fingerprint reader after adding self signed certificate

Question: Cyanogen OS 12.1 running on a ZUK z1. I added a self signed CA certificate to the "trusted credentials". Since then android doesn't allow me to use the fingerprint scanner to unlock the screen anymore. Is there any workaround to this security feature?
Comment: Is the device rooted? Otherwise AFAIK the answer is 2-letters: No.
Comment: Ouch. It is not rooted unfortunately
Comment: Shall I place a "root solution" as answer nevertheless, so you can see whether it's worth it? On a rooted device, the solution is trivial (even if you're not familiar with shell/command-line). I do that on my devices all the time.
Comment: Yes please, post it. I just don't like tools like kingroot and success rate of rooting my device through other ways is still pretty low.
Comment: I'd rather avoid those tools as well if possible, because of their side-effects (at least from what I've read about them). Will check with the answer, but must postpone it to when I'm back home – there are some subtle details I cannot reconstruct reliably without my notes :)
Answer: Step 1: Make the certs compatible (if they are not already)
At the very beginning we need to figure the file name of our the cert file. The name of the cert file is a hash one can obtain from the certificate itself. For this, one needs the openssl tools. On Unix/Linux the steps are then as follows:
# Obtain the hash – in my case that returned d6a2705a – so we have the file name
openssl x509 -inform PEM -subject_hash_old -in root.crt | head -1
# Copy the original file
cat root.crt > d6a2705a.0
# Append additional data
openssl x509 -inform PEM -text -in root.crt -out /dev/null >> d6a2705a.0

Step 2: Get the cert into our system cert chain
If your device is rooted, a solution to this is importing the certificate as system cert (not user-cert). You will need the command line for that, using either adb shell or a terminal app on-device. The following snippet assumes your certificate was already pushed to the SD card, saved as /sdcard/d6a2705a.0 (adjust that to your cert name), and you're at the command prompt of your device.
mount -o remount,rw /system
cp d6a2705a.0 /system/etc/security/cacerts/d6a2705a.0
chown root:root /system/etc/security/cacerts/d6a2705a.0
chmod 0644 /system/etc/security/cacerts/d6a2705a.0
mount -o remount,ro /system

Done. Now you should be able to use the cert – and as you do not have any "unsafe user certs", you're free to use whatever unlock mechanism you prefer.

A quick check shows all these steps are also described in the CaCert Wiki on how to create Android compatible certificate files from their original files. So my personal notes I took the above from might well originate here, at least partly.


AP switching time

Question: I need to ask that how much time is taken in WiFi roaming (switching between the APs).
I am asking about Cisco APs, Cisco outdoor/industrial routers that can connect more than 1000 people, and any other company you people know.
Answer: With a controller to coordinate the associations, handover is very short in order to keep voice call quality acceptable.  Aboslutely not for 1,000 users but without a controller you can see 1 second dropouts routinely.  Badly organised controllers in public spaces can easily be observed to drop out for much longer, perhaps 30 seconds.
Comment: Do you know any of the wireless LAN controllers?
Do you have any knowledge on Cisco Aironet 1572EAC AP? On the website it is stated that more than 1500 devices can connect to it.
Comment: I don't know that particular device but the max connections limit of software is normally way higher than the max with acceptable bandwidth/user in any particular situation.  If you you have 1,000 users you need to work on the bandwidth budgets and management throughout your network.

AP switching time


Is schmuck really an obscene word?

Question: Schmuck is supposedly an obscene Yiddish term for the male sex organ, yet it appears all of the time in the media as an American idiom for a jerk.  Can one use it in polite company?
Comment: @KristinaLopez And there is already an intersection between "male genitals" and "family jewels"...
Comment: The obscene meaning is intriguing because I wonder how it came to that definition since the German word "Schmuck", means "jewelry"? ;-)
Comment: @KristinaLopez:  Rosten comments on that.  He said schmuck does come from that German word "some way or another," but that the Yiddish word for ornament (or jewelry) is "schmock".  Interestingly, he notes that there is a Slovene word "smok" that means fool, but it was derived by the Yiddish word.
Comment: That's why language is so gosh-darn interesting!  Imagine the timelines crossing where "jewelry" and "fool" intersect! lol!
Comment: [Etymonline](http://www.etymonline.com/index.php?term=schmuck) has a good entry for _schmuck_ which refers to Leo Rosten just as you have.
Comment: a comparable case might be the casual use in English of the vulgar Spanish word "cojones."
Answer: As Bruce said, the word "schmuck" may be more familiarly used for "jerk" today. (The TV show Golden Girls used it regularly to refer to Stan, the ex-husband of Bea Arthur's character, Dorothy.)
But since you asked about "polite company", I would take it a little further and suggest that name-calling or referring to someone as "jerk", "idiot", "bimbo", etc., is just not considered polite and all such words, including "schmuck" should be avoided in those social settings.
Comment: Example of both usages:  Moskowitz is told that if he wants to make an impression in Miami, he should buy a camel and ride it up and down Collina Ave. and his phone won't stop ringing with social invitations.  So he does.  One day, the parking attendant reports the camel was stolen.  He files a police report. Officer asks, was the camel a male or female.  "I'm sure it was a male," said Moskowitz.  "How can you be sure?"  "Because everytime I rode it up the street, someone would say, 'look at that schmuck on the camel.'"
Comment: oh, spot on, Bruce!
Answer: Leo Rosten, in his classic (and funny) book, The Joys of Yiddish (McGraw-Hill 1968), says the word schmuck is defined first as an obscene reference to the penis:  "Never use schmuck lightly, or in the presence of women and children.  Indeed, it was uneasiness about schmuck that led to the truncated euphemism shmo ....", wrote Rosten.  Ibid. p. 361.  A secondary definition was "(Obscene) A dope, a jerk, a boob; a clumsy, bumbling fellow."
It seems to me that the word's status as an obscenity has lapsed.  Merriam-Webster.com leads the definitions with "jerk," acknowledges the Yiddish definition as the origin, but drops the indication that the term is an obscenity.  Moreover, newspaper editors have been bold enough to use the word in headlines.
This change appears to be confirmation of the prophecies of Lenny Bruce, in his stand-up routine, and Allan Sherman, in his 1973 book, The Rape of the A.P.E (American Puritan Ethic : The Official History of the Sex Revolution, 1945-1973: The Obscening of America, an R.S.V.P.) (Putnam Publishing Group), who said that if you say an obscene word enough times, it will lose its shock value and come into common usage without raising any eyebrows.
Nevertheless, I would still refrain from using the term among older Yiddish speakers.
Comment: You might compare it to the UK English slang term "berk" which was originally from rhyming slang for c-nt, but has become a mild insult divorced from the origin.
Answer: When a word borrowed from another language passes into English, the tenor of the word, as understood by speakers of that first language, doesn't always come through. An example of this lost-in-transmission phenomenon is schmuck/shmuck. In Hooray for Yiddish! A Book About English (1982), Leo Rosten begins a lengthy discussion of shmuck as follows:

shmuck Obscene as all get-out, but effective. From German Schmuck: ornament...jewel...gewgaw.
A handful of readers of The Joys of Yiddish wrote to protest my including so "dirty" a word as shmuck in that lexicon. I cannot sympathize with their prudery. A dictionary is not a hymn book. ...
[Meanings of the word:] 1. (Taboo) Penis.
Because shmuck is considered so improper, the truncated shmo was invented.
Never use shmuck before women, children or strangers. I may add that, on the whole, Jews are puritanical in public about the pubic.

(Still taboo) A fool, a jerk. ("What a shmuck to fall for that trick!")

(Still obscene) A traitor, trickster, hypocrite or hype artist. ("He's just a low-down, lying shmuck!")

...
Please note that shmuck began as the German word for an ornament or jewel. The word was not lewd in German nor obscene in Yiddish. How did the connotational leap take place from "jewel" to "penis"? By mothers bathing or drying their baby sons. They would croon over them. What better word for the member than "little jewel...ornament...crude pendant." In English, men josh about "the family jewels" and they do not mean rubies. German or Hungarian nurses and governesses, I am reliably informed, used the euphemism shmuck. Jewish mothers and sisters were puritanical enough to refer  to "that place" or "that (his, her) thing."

Compare that treatment to Rosten's discussion of putz in the same book:

putz Rhymes with "cuts." German: Putz: ornament. (Vulgar)
As a noun:

Penis.

But putz is often used, with condescension, for

A dolt, a fool.

A shmeggege, a pigeon, a yokel.

As a verb:

To waste time (as the English "futz")

To sleep around, to be promiscuous.

Some arbiters of language hold that putz is slightly (but only slightly) less vulgar than shmuck (q.v.); others consider putz slightly more offensive because it aims to be euphemistic. Avoid both words. (But to those who love the punch of the colloquial: use putz only after you see who's present.)
See SHMUCK (taboo).

So even though both words meant "ornament" in German (according to Rosten), and even though both mean "penis" in Yiddish, Rosten identifies shmuck as a "taboo" word among Yiddish speakers and putz as merely a vulgar word.
The offensiveness of a word in its native habitat is of course no sure guide to its sense in a different language that has imported it, but the connotations that the word has or had in its previous environment remain relevant insofar as speakers of the exporting language may be present to hear it used in the new one. It's all very well to say that in recent years shmuck has lost its taboo status in English (if it ever had such status, which I doubt), but in Yiddish it may remain highly charged and offensive—and English speakers would do well to bear that in mind before they throw it around as if it were no more insulting than jerk or idiot.
Comment: Rosten is an entertaining writer with a good knowledge of Yiddish, but his etymologies are weak. Although Yiddish is a Germanic language, it has heavy borrowing from Slavic languages, and *shmok* / *schmuck* is one of them. It doesn't come from German, but from Polish *smok*, which means "snake".

Is schmuck really an obscene word?


leaking coolant driver side half way back on engine in 2001 chevy blazer

Question: on the driver side about half way back on engine block coolant pooring onto the ground. I thought it was the lines coming of oil filter that run near tansmission but I took it off that's a oil line not coolant. i didn't see anything coming out top of engine or near heater core. this is not my first rodeo but i don't see no coolant lines on driver side. could it be the intake. where the coolant hits the ground it is like halfway back on the block and its a major amount coming out any ideas
Comment: Do you have any photos? Is it at the top of the block (between block and head), or further down? Are there any distinguishing features that it looks like the coolant is coming from? (for example, a round depression in the side of the block, which will house a core plug)
Answer: Assuming that you are correct and their are indeed no coolant lines around there, I can only think of 3 things, but the second 2 are certainly grasping at straws

Freeze plug.  Nick C called it a core plug.  If one of those is no longer sealing or is gone completely, you would be pouring coolant and it might be very hard to see.  Feel around for a hole, preferably with the engine off.
You've got a tear in a line someplace nearby that is spraying all the way over to the block.  Or the water pump or some other accesory with the same problem.  From the way your question is worded, it sounds like this is not the case.
There is a non-factory hole in the side of the block that punches through to a coolant channel.  Maybe it rusted out (somehow), maybe it got shot at, maybe somebody with a drill really hates you.
Comment: The core plug is a remnant from the casting process - it is not designed to save the engine from damage due to freezing : have seen damage that is between , above or next to the plug while the plug is perfect...


MiniDLNA or Mediatomb audio pause for about 4 secs during music playback

Question: I have tried both miniDLNA and Mediatomb as dlna servers (installed separately, never both at the same time). I have a small Dell 1012 Mini (Intel Atom), running 14.04 (installed on an SSD). My music and other media is stored on an external HDD (encrypted LUKS), and my media is found and indexed (stored in a database) without problems (well I have to restart the dlna server because the disk is not unlocked and available before the dnla server starts, when I boot the notebook).
During playback, things generally work fine, except now and again, say every 15 to 30 mins during an mp3 playback (different songs, it doesn't matter what I play) on my ipdio internet radio, the music pauses for about 4 secs before carrying on. The wireless connection is not lost, and the internet radio doesn't complain. The pause happens, and then music play continues.
I used to use an iomega NAS drive for my media, and that was 99.9% reliable. It did also pause very occasionally, maybe once every 30 hours of playback (also using the same ipdio radio playback client). So I think the difference here is now the notebook is the server, and I have a USB encrypted HDD for my media. The iomega NAS drive was standalone, and not encrytped
The Dell mini 1012 with the SSD is reasonably quick, but I'm still getting a pause. I'm sure the Dell has more CPU power than the iomega home media network drive.
I'm thinking, something must be interrupting the stream to the client, but what? I'm sure the internet connection to the client is fine (its wireless), as I can hear internet radio with zero problems. And because both miniDLNA and Mediatomb have the same symptoms, then it is likely to be perhaps the system accessing the media HDD (which is symlinked to my directories in my home directory).
I've looked at syslog, and see nothing, I've looked at both the logs for miniDLNA and mediatomb, and they do not log any problems
What else could I look at in terms of logs? Might usb access logs help?
What could be causing the random pause of approx 4 secs?
Is access to a USB encrypted external drive a low priority?
Even if access to a USB external drive is a low priority, I would of expected not so low that a 4 second pause is heard.
Basically, how can I go about fixing my audio pause problem, so that I can listen to music without have a random sudden pause for a few seconds?
Update
I unistalled mediatomb, and went back to minidlna. Because I feel I had more pauses with minidlna than mediatomb. But I have no statistics to back that up. My plan being, if the problem occurs more, I have a better chance of capturing it in a log file.
I also copy some mp3 albums onto the SSD of the notebook, and setup minidlna to only access the albums on the SSD (so the encrypted symlinked HDD music collection is not being accessed). I'm hoping then this will isolate where the problem area is. Is it the DNLA server and connection to the client, or is it the USB access to the encrypted drive? Well it didn't take long to answer that question. Tom Jones was suddenly paused for a few seconds during playback! So access to the USB encrypted HDD doesn't seem to be a problem.
The problem seems to be in the server to the client. The problem could be in the client, but while it worked 99.9% of the time with a NAS drive setup, then its likely not the issue. I'm using the same WLAN router too. The only changes are now that the Dell mini 1012 is the DNLA server.
Any ideas where I should look next ? Turn the debug level up on minidlna?
Comment: I've been experimenting with renice and ionice. I have a combination that appears to work.
setting the minidlnad to -10
and a ionice of real time priority 4
seems to stop the pauses
Answer: As mentioned in my comment. Using renice and ionice seems to have fixed my problem.
A combination of setting the minidlnad to -10 and an ionice of real time priority 4 seems to stop the pauses.


Which model to choose: GLMM or GEE?

Question: I have data with a binary outcome (success/failure) and a binary explanatory variable (treatment/control). For each subject (this is a clinical study), I have two observations, coming from two eyes. Obviously, the observations are correlated within a subject. I wonder if I should use GLMM or GEE to compare the two groups and to calculate the probability of success in each group. I wanted to ask what you think. I know the basic theoretical differences (that GLMM estimates a regression for each subject and GEE averages them all), yet I wanted to ask if anyone can specify the similarities (most of the time I get similar proportions), and the differences. How do you choose a model ? Based on what ?
Answer: Both of the models can be the correct approach. Both of them can deal with non-Gaussian distribution of the outcome variable and both can deal with the dependency (within subject) in your data. The important question would be: what specific research question are you aiming to answer? In an experimental design the individual subjects might be of interest. In that case a GLMM is preferred since it leads to an interpretation for individual subjects. If you are interested in the overall effect on the population a GEE is the model of choice, since it leads to an interpretation of regression coefficients for the population.
Comment: Thank you. So in this case, if the question is to show that treatment A is better than treatment B, should I use the subject specific model ?
Comment: If you expect different effects for different subjects you could. But as I understand it, you are interested in the effect of the treatment on the group (and not on the individual), so GEE would be the way to go. Again, none of them is wrong, but interpreting the effects of GLMM as effect on the whole group would be wrong.
Comment: I see. And one more question please. What is the difference between a GEE, and an "R Side" mixed model ? In SAS terminology, what is the difference between PROC GENMOD and PROC GLIMMIX with the residual statement?
Comment: Look at what the abbreviations stand for. GENMOD is for Generalized linear models (no mixed effects). GLIMMIX is for Generalized Linear Mixed Models.

Which model to choose: GLMM or GEE?


How is there no murder trial in Southpaw?

Question: In the movie Southpaw, how is there no trial for the murder of Maureen? Given the presence of only a handful of people in the event and the bullet fragment/shell (and possible surveillance cameras), it would have been easy to investigate the murder and locate the killer. Why is the murder simply ignored, given it was a high profile killing?
Comment: (rant) The Law was keen on separating him from his child for his drunken driving but didn't seem to care about finding out who murdered his wife?
Answer: In this deleted scene Billy Hope (Jake Gyllenhaal) talks to two police officers who are assigned to the case, they outline a few problems with evidence, meaning that they cannot find out who the killer is.

As of the time they are working on the case (two weeks have passed)
there is no video evidence of the shooting on cell phones or CCTV cameras
There have been no eye witnesses to the shooting, including Billy
himself who didn't see it, although claims Miguel Escobar's brother
Hector was the one who did it.
They say "No one is talking" and that they "Don't want to be involved"

For a trial to take place, the officers would have to gather evidence on one of the individuals and charge them. Because they have none, a trial would be out of the question. This explains why Miguel Escobar and his companions do not face any repercussions.
Comment: Thanks for that, the scene just makes it feel like even the cops don't want to side with Billy. Finding the bullet shell from the scene would have not been very tough. Further, tracing to the gun would be relatively simple given the attendees are known. The scene suggests that no shooting can lead to an arrest without eye witness.
Comment: However, it answers my question, even if the movie makers didn't think much about the trial. Thanks for that.
Answer: there was actually but the hall was full of people there was not really eyewitness everyone was busy! it was Escobar's brother who shot her and i think there was a little scene about it Billy talking to the police & there is a deleted scene about it he was arguing with the police & they do nothing about it that's why he decides that he is gonna go kill Escobar brother's wife and than when he sees she's got kids he stops
Comment: Can you provide a bit more info about the deleted scene, such as a link or a fuller description?
Comment: I would be eager to see this deleted scene too.


Does this site use a good UI for shopping cart?

Question: Does this site use a good UI for shopping cart? How do you drop something in the cart? Is it intuitive enough to be used?
Comment: No?

You're asking us the same question as before, which was closed out.
Comment: The other one wasn't phrased as a question. I'd say this is fine
Comment: @mariocatch: Pay attention to the reason why it was closed.
Comment: Added a screenshot so we can see what you're talking about. (Anyone who's interested should still visit the site to see how it works.)
Answer: Not really, I think.
The main irritating thing is that you can't drag an item from the front page (the link you gave). If you try to drag the image or the name of the set there, it doesn't work. And, that is a bit strange as the shopping cart is visible, and explaining you to drag items into it. It remains unclear what 'an item' is.
You have to get to the icon set page (which is a bit hard as you only get there via the small link, not via the image or the collection header) to get to something they mean with 'an item'.
Second, when dragged, the item doesn't directly show that your drag was successful. When you hit the cart the display remains the same as if you were somewhere else on the page or not even dragging at all*. It takes a while before a wait-icon is visible and it becomes clear that you have dragged successful.
These two things should be improved I would say.

Don't show the cart on the front page or make collections dragable.
Make it clear directly that items are dragged in the cart correctly.

(* Apparently you don't even have to drag items in the cart, just start to drag them and it works..)
Comment: I say make it visible on the front page ONLY when you have items in the cart and do not show "drop..." in the cart if you can't do this action on the current page.
Answer: First, I noticed the "shopping cart" area on the right and the advice: "Drag item here to shop".
I tried dragging one of the large, inviting images from the home page right into the cart, but that didn't work.
I then noticed that each image actually represented different sets coming at different prices. I tried dragging the set link on the bar. However, that also didn't work.
I afterwards tried dragging the description, again the image, the whitespace in each product_item div... nothing.
I finally decided that I would open a set page, which featured a prominent "Add to cart" button and a "+" button over the image. This would let me purchase items traditionally, but made the dragging tip even more confusing: did I miss something on the homepage?
I skeptically tried dragging the large icon from the set page on the cart. That also didn--- oh wait, that's a throbber... and now it's there, unlabeled and scaled down.

Things you could consider: (to be taken with a grain of salt)

Make the cart "react" to a "legal" drag and drop action in progress. Like this.
React to user mistakes. Detect an item to drag and drop large icons where it doesn't make sense and display an error message. For example: "This collection comes in a number of sets. Which one would you like to purchase?"
Be more reactive client-side. On drag and drop, show the item as dragged and disable the checkout button as you update things server side. This site handles voting like this, for example.
Comment: I love how @badp actually shows usage examples here.
Answer: Yes
I don't see a huge problem with it. As well as drag-and-drop, the icon set pages (that can be reached by clicking on them) have add to cart buttons. I also like the fact that, unlike many other online stores, you don't have to visit another page to see the contents of your shopping cart.
However, one big problem is that it doesn't work without javascript, or at least display a warning to users without it enabled that it needs to be turned on.
Comment: sorry, but NO. the part where you don't need to visit another page to see your cart can be implemented on any basic shopping site. they usually show your cart on a seperate page as a way to confirm you're indeed buying the stuff you want to buy. secondly, what's easier for a user to do. a single click on a target, or a click, on a target, a drag to another target and a release there, without leaving the target.
Answer: It's like one of those fancy UIs we see in movies that we don't in real life, not because they're hard to implement, but because they're hard to use.
For someone with difficulty in motor skills, this can be quite hard to use. Dragging and dropping using a trackpad isn't often as responsive as doing it with a mouse. (Some trackpads just happen not to be very responsive.) What could be done with one click now needs a mousedown, a precisely targeted mousemove, and a mouseup. Basic knowledge of Fitts' law can tell you why this is a harder task than simply clicking a button.
There is a reason computer interfaces do not try to mimic real life interfaces (which is what this UI is trying to do, IMO.) That's why we don't walk through "aisles" of "3D stores" but instead have pages dedicated to products where we click the "add to cart" button. What is natural for a walk-and-pick-up UI is not natural for a WIMP (windows, icons, menu, and pointing device) UI.
Answer: NO

First of all, a critical UI bug, customers with screen heights below the shopping cart height are unable to checkout. (think netbooks with screenheights of 600px.)
Shopping cart activity is shown on pages where there is no activity, text doesn't specify what to drag in the cart. (solution would be to )
No pricing information availble when changing license option.
Seperate Pages for "Vector Set" "Vector Single" and "Pixel Set" are unneeded and confusing. (a single page with buttons "Buy whole set (vector format)", "Buy whole set (Bitmap format)" and the header "Or buy icons individually", with the individual icon buy options below is less confusing)
Throbber is slow to appear, and not in the focus area when using the plus buttons.
Shopping cart does not make a difference between different versions of the same set.

I think I should stop now.
Answer: It's OK.
I think it is one of those cases where they let the coolness distract them from the core functionality. It is a bit hard to use, shows very little info about what is in it.
So I would say that it is OK, most users would be able to buy there yet I don't think I would use it in my site.
also like @simon said, it would be an issue if JS is turned off.
Comment: Why is it OK if it's hard to use? Do you prefer prettiness over functionality?
Comment: OK as in mediocre, not good just OK. It works but has some issues.
Answer: It took me a while to figure out why you added the drag-and-drop option because it wasn't obvious that it is possible to buy individual icons and not just sets.
I added a set and then tried to add individual icons but when I tried to add an icon that is a part of the set I already added - it just wasn't added. It's confusing and frustrating.
The cart is showing small arrows on the top and bottom for scrolling when there are many items in the cart. It's also confusing. Maybe just show these icons when the sixth icon is added or show a small part of the sixth icon so I would know there are more. Now I add additional icons and can't figure out where they went. Scrolling didn't work for me using Chrome 6.
It found it strange that you can't drag and drop by clicking the plus sign. BTW - the tooltip says "Remove".
Although this feature is cute, I prefer a single click on the add-to-cart button or plus sign than dragging items to the cart. It's more efficient.
I read somewhere an opinion that pagination is not really needed anymore, especially when it comes to pictures. The human eye is great at seeing many images and picking the ones you like. It may be easier for buyers if you just show all the icons on a single page - a much better shopping experience.
Site looks great and the icons are excellent.


how to install adnet 802.11n wifi adapter driver?

Question: i am a new user in ubuntu and i am unable to install my wifi adapter driver i.e of adnet 802.11n please help i had uninstalled my previous windows os
Comment: Let's start by identifying your exact device. Insert the device and run this terminal command: `lsusb`. Next, edit your question to add the result. Welcome to Ask Ubuntu.
Answer: First check your USB configuration by typing lsusb in your terminal and check it.. see the image for more info..

If your USB configuration is this 0bda:f179 Then you can try this following commands...
install :
sudo apt-get install build-essential git dkms linux-headers-$(uname -r)
git clone https://github.com/kelebek333/rtl8188fu
sudo dkms add ./rtl8188fu
sudo dkms build rtl8188fu/1.0
sudo dkms install rtl8188fu/1.0
sudo cp ./rtl8188fu/firmware/rtl8188fufw.bin /lib/firmware/rtlwifi/

Run following commands for disable power management and plugging/replugging issues:
sudo mkdir -p /etc/modprobe.d/
sudo touch /etc/modprobe.d/rtl8188fu.conf
echo "options rtl8188fu rtw_power_mgnt=0 rtw_enusbss=0" | sudo tee /etc/modprobe.d/rtl8188fu.conf

How to uninstall :
sudo dkms remove rtl8188fu/1.0 --all
sudo rm -f /lib/firmware/rtlwifi/rtl8188fufw.bin
sudo rm -f /etc/modprobe.d/rtl8188fu.conf

Comment: Please be aware that installing the wrong driver can rise future compatibility issues with OP devices. Providing a more general answer would be preferred, as well as waiting for OP to provide more information about their hardware.
Answer: Just a shorter version from the GitHub link given in the detailed answer by @Vashishth Patel that worked for me is:
sudo add-apt-repository ppa:kelebek333/kablosuz
sudo apt update
sudo apt install rtl8188fu-dkms


How to clash lightsabers?

Question: I was looking at one of the trailers for Battlefront. At the end Vader and Luke clash lightsabers. How can I clash lightsabers?
Answer: To clash lightsabers both players need to press Triangle/Y (heavy attack) on PS4/XBONE at around the same time
Answer: Both people need to be locked on, or close to it, (on Xbox one this is done by pressing in the left stick) and both need to use the strong attack at roughly the same time, then you need to button mash to win the clash.
Comment: They don't need to be locked on. Just aiming in their general direction

How to clash lightsabers?


"I saw him TAKE it" and "I thought he KNEW it"?

Question: I'm confused by the use of these two tenses  "I saw him TAKE it" and "I thought he KNEW it" Why I saw him + infinity form verb but I thought he + past tense??
Comment: Your second sentence is not grammatical as written. It ought to be "I thought **he** knew it."
Answer: These are just the constructions that those particular verbs happen to take.
"Think" takes a "that" clause, which is finite and therefore tensed (the "that" is often omitted):

I thought [that] he took it.

"See" (in this sense) takes a non-finite clause (and if its subject is a pronoun, it is in the oblique case):

I saw him take it.

You can say "I saw [that] he took it", but it has a rather different meaning: something like "I saw something that led me to conclude that he took it, but I didn't necessarily see him actually take it".


Are the collected papers of A. Einstein, entirely translated into English?

Question: I need some Einstein's papers translated into English. There is one complete collection of his papers but only a few of them have been translated in English. The rest are in their original language -- German, which, unfortunately, I can't read. Have you seen anywhere all of his paper translated in English?
Comment: Do you know you can accept an answer (if it's useful to you) by clicking in the tick or check button that are on the left margin of the answers? Sorry if you already knew.
Comment: You wrote: "There is one complete collection of his papers". Could you please specify which collection you meant? There is, at least, one more that I am aware of - published in 1965 but it is translation into Russian (four volumes).
Answer: The published papers from the 1902-1920 are translated in the collected papers of Albert Einstein, which is a series of books you can find in many libraries, homepage here: http://press.princeton.edu/catalogs/series/cpe.html , this series is full of junk like private correspondence and such, but the publications are in there too.
From 1933 onward, the work is published in English, and this includes EPR, wormholes, unified theories, Einstein-Infeld-Hoffman approximation, and others. So there is only a 12 year gap--- 1921-1932 unfortunately some of his most productive years. The 1920s papers include great classics, and will be published in English eventually. There are good extant translations of the laser/BEC paper, the A-B spontaneous/stimulated emmission coefficients paper, and perhaps the seminal 1924 Hamilton-Jacobi equation quantum mechanics paper.
It would be good if somebody did a translation of the scientific publications only, leaving the personal junk for another time.
Comment: Thanks Ron. This is my impression too. Now, I need for instance Einstein A., Ehrenfest P., Z.Physik, 19, 301-306 (1923) and can't find it translated. There are several other from the same period you mention that haven't been translated. Isn't it a shame to have such a great scientist not fully available to the English-reading audience.
Comment: If you post an online link to a German version, someone might translate it. You could also try to to Babelfish it and figure out what they are doing from context.