Javascript Function Called Too Early in PHP Script

Question: I'm working on a Google Maps plugin.
My problem is that the function that initializes the map, csf_map_maker_js(), is getting called too early-- before the div is defined (at least that's what I think is the problem).
In the PHP, I've got:
$csf_map_output .= '

';

$csf_map_output .= '';

return $csf_map_output;

I don't think that the csf_map_canvas div is ready when the function is called.
In the javascript script, the csf_map_maker_js() function is defined outside of jQuery(document).ready(function() {});  . If I move it inside, will the csf_map_canvas div be ready when the function is called.? If so, how do I change the function call in the PHP script in order to call a function in an anonymous function? How do I get around the scope issue?
Is there another way?
Answer: if u think that is the problem simply do:
$csf_map_output .= '';

I don't see any scope issues with the above code.


Can I get NL Student visa after UK visa refusal?

Question: After trying and being refused twice for tier 4 visa in the UK, both on finance reasons, my plight can be read about here (UK student visa refusal)
I'm looking at applying to university else where in Europe, and the Netherlands have a couple universities that I like. Will it be a problem for me if I declare everything and is truthful on my application form?
Answer: The UK refusals should not be a problem of themselves.  The most likely possibility is that the circumstances you showed to the UK, which were inadequate and resulted in a refusal, will also be inadequate for the requirements of the Netherlands, and will therefore result in a refusal there as well.
On the other hand, it's possible that the Netherlands evaluates such circumstances differently, and might therefore accept your application.
Above all, you should not try to hide your history with the UK.  You will very likely be found out, and a visa refusal for deception will make it difficult for you to get a visa anywhere for a very long time, perhaps for the rest of your life.
Your experience with the UK shows that your financial situation is complicated, and that your applications were not always optimally prepared (in particular, you didn't always have a full understanding of the rules governing your application).  You are likely to have a better shot at approval if you hire a reputable professional to prepare the application.
You should most likely look for an immigration lawyer in the Netherlands rather than an agent in your home country, since we have heard many stories of such agents being unscrupulous, or at least insufficiently familiar with the rules of the foreign country with which the visa application is being filed.  For a local lawyer, the country isn't foreign, and the lawyer is a specialist in the law of that country.
Comment: By the time of application of Netherlands visa I will 18 and be able to have my parents transfer the money into a bank account in my name. Will that help the situation? as I no longer need to prove the association or anything like that. The money was always there and ready to use, the only problem we seemed to have was showing that I had access to it. @phoog
Comment: @A.Ren I think you have misinterpreted your refusal notices. All the more reason to get professional assistance.


Growing beneficial, edible plants in the woods

Question: We are purchasing some land in northern KY. and want to start growing food in the wooded area. We plan to plant ginseng but beyond that we are looking for other suggestions as to what we can grow in this thick woods. Very little undergrowth, older forest with a creek near by. Lower level floods in the spring for a short while so that could be helpful with certain plants. Mostly hardwoods, in hardiness zone 6b.
Comment: It's 95% Mixed hardwoods with a cluster of pine at the top. We plan to take the pine out and build a cabin there. We found a ton of turkey tail mushrooms in the fall. Hoping to find morels in the spring. Probably wont cut much else out till late next year so I can see what grows there naturally. We love medicinal mushrooms!
Comment: This actually sounds like the ideal situation for forest based mushroom cultivation.
Comment: What kind of trees do you have on the land?
Comment: Do a google search for "food forests" lots of good to research.
Comment: There was a good programme on BBC 2 uk last night big dreams and small spaces, with a person wanting a productive garden in a woodland setting. This should be on catch up TV if you can get it. The gardeners visited a mature woodland garden and included thornless brambles.
Comment: I expect deer, raccoons etc. are anxious for you to get started.,
Answer: All of the currant family (red, black, gooseberry, lingonberry...) do reasonably well in shade.
High and low bush cranberry do well in shade.
If you have light shade, look at nut trees.  It will be a good while before they produce, but it's worth a look.  Hickory, hazelnut, walnut, beechnut are possibilities.
I recall that one of persimmon and pawpaw do ok in shade.  Same source said that one is wonderful and two is tiresome for both fruits.
Most plants that produce significant surplus for eating, need full sun or close to full sun.  E.g. Raspberries will grow well under a dense poplar canopy, but will only produce a few raspberries per cane, where the same plant in full sun will produce dozens.
Another possible product for you is mushrooms.  There are a bunch that are fairly easy to produce on logs.  Here the big ones are Shitake and Oyster.

Another consideration is to clear some of the land.  Your photo looks like a fairly mature forest.  You could clear half to 1 acre clearings.  One acre is several year's fire wood.
Comment: If you have dead, dying diseased or recently downed hard woods, Oyster, Shitake & Lion's Mane Mushrooms would be great choices. Also maybe look into what wild mustard greens you have in the area. Or consider spreading some Miner's Lettuce seed.
Answer: You are going to have a very difficult time growing much in the forest portion of your land. Yes, currants and gooseberries, black raspberries, and possibly sour cherries will tolerate the shade and fruit, but most things will not. As far as vegetables go, you should be able to grow leafy greens - especially in the spring before the trees have leafed out, but I wouldn't expect too much more.
Where you will have an opportunity is at the edge of your woods on the upper right side of the photo, and possibly along the creek. Many fruits and veggies grow very happily in the margins.
As others have mentioned, look into resources on Forest Gardening. I like How to Make a Forest Garden by Patrick Whitefield, personally. The rub is, though, that most of the books out there on forest gardening that I have seen are about taking a relatively empty lot and planning out a garden that will eventually grow into an edible forest. They help you plan a forest-like garden with tons of margins where yes, there are big trees, but there is also a lot of sun light. To start with a mature woodland like you have, you will either need to work at the margins that you already have like I have suggested, or be willing to take down some trees in the center to create a margin of your own where the edible plants will get some sun. Otherwise you will be very, very limited in what edibles you can grow.
Answer: What a lovely opportunity, could try Runner beans Phaseolus coccineus, Blackberries Morus Nigeria, but they can go a bit mad, so plant with caution. Ben Law, is a woodsman, who lived in a wood (strangely) he built a house of straw bales, and came to prominence via Grand Designs a tv programme in the uk. He planted many fruits, nuts   and other types of fruit and veg. He has written a book, which may be of some help. There are a couple of nut trees that you may be able to grow, depending on whether or not you have 'livestock' that may graze on your produce.
Comment: I recommend looking up concepts like "food forests" something permaculture advocates use when planning homesteading spaces.
Answer: No undergrowth forest plus creek makes me immediately think of allium ursinum (European variety) or allium tricoccum (US native). Both are happy to cover the forest floor in spring and disappear later in the year. If you are lucky, they take hold and propagate themselves.
Not exactly a mass food source, but a spring kitchen staple for me. Used fresh in spring, stored as pesto or herbed butter for the rest of the year. Both are considered "cleansing" foods in spring, I just love the taste.
Another garlicky herb is Garlic mustard, which makes a nice "garlicky spinach". It's an invasive plant in the US, so please do not introduce it, but there is a good chance that you already have it.
In Europe, the soft new growth of of European Silver firs (Abies alba) and Norway spruce (Picea abies) is turned into a sugary srup that is used both as tasty "honey" and cough syrup. Depending on what grows in your woodland, you might find some, too.
If the wetter areas closer to the water have light / somewhat sandy soil, horseradish might be quite happy there. You can go the full harvest / replant route or simply let it grow wild and harvest what you need. Note that horseradish also has invasive / wandering tendencies, but can be kept in check with underground barriers, if necessary.
If your forest doesn't allow enough sun for raspberries and blackberries, note that their young leaves can still be used in herbal tea mixes.
Another common "nuisance" are stinging nettles (Urtica dioica), that make an excellent "spinach" and a herbal tea which is also described as "cleansing".
If the water of your creek is clean enough, consider a "trench" for watercress or plant it right on the bank. The trench might give a higher yield, but obviously needs more care.
Purslane also loves coolish, wet conditions, as the days get hotter, it turns red and the season is over.
Comment: @JasonWhipple, that's *exactly* the category these alliums (rams, bear garlic) fall into. If you already have it, [Garlic Mustard](https://en.wikipedia.org/wiki/Alliaria_petiolata) can be used like garlicky spinach (before bloom). Do not introduce it, as it's considered invasive in the US.
Comment: I think we have plenty of cleared land by the road to cover most of our needs. We have an acre there so any little things that we could add in the forest is just a plus. Thinking of medicinals as well.
Answer: Nuts of course, and some floor plants, will be naturals, but so as not to repeat others' answers, I thought I'd point out the issues/other things I noticed about your idea, rather than listing plants.
No undergrowth means there isn't enough sun for the undergrowth. The lower tiers, and the floor, all depend on the amount of light let through the top canopy. If there isn't even enough light for those, you will have trouble growing almost all cultivated foods.
In the summer, everything uphill from the creek will become very dry, and the food crops (especially those yielding fruit) will need irrigation. You will find more underbrush near the edge (up by the road). If you clear that out, the edge biome will have a much more diverse set of options. And the grassy strip at the top will grow quite a lot.
Personally, I'd plant in only a portion of the woods, because mature hardwood forests in a steady cycle aren't all that common anymore, and replacing the natural habitat can throw some things off. I would fence off the planting area with 8' deer fence (remember, deer don't always find specially grown food crops in the woods, and will make short work of a lot of them). Berry plants will need protection from birds.
Comment: +1 for pointing out that no undergrowth as an indicator of low light conditions


How can I make my boots less of a nuisance in the airport?

Question: I wear boots for business wear due to some foot issues, but they can be a pain when going through airport security.  Airport security often requires you to remove your shoes before you pass through the metal detector/scanners and boots cannot simply be "slipped" off and on. I don't like to wear different shoes just for security because the boots take up more space than my single carry on allows.  Are there any ways I can expedite the process of boot removal?
Comment: There are some airports these days that ask everyone to take off their shoes before walking through the scanners.  One example being Keflavik which I flew from yesterday.
Comment: AFAIK The TSA (Transport Security Administration) in all US airports require one to take off their shoes and put them in a bin to go through the X-Ray machine.
Comment: What exactly is the problem? Is it enough metal to set off the detectors? And also where exactly is it a problem? I've had boots on before, and they've set off the detector, but after manual detector scan I've never had to take them off.
Answer: I work for an airlines and I see some of the maintenance personnel and some military-like personnel who work inside the airport ramp go through this issue almost in daily basis at the staff security check because they wear boots as required by their job. They take off their boots way before reaching the security check area (or at the parking area or even home) and wear some light slippers like the ones in hotels (these won't take much space as they are extremely thin and light, some are disposable). Once they reach there they just put the boots in the x-ray machine and go through the security check quickly and smoothly then sit in the chairs after the security check and take all the time in the world to put back their boots.
Not sure if this will work for you but hopefully it will.
Comment: Thanks!  I'll have to see if I can lay my hands on some slippers.
Answer: When I've had to wear my boots due to not having space left in my luggage I generally loosen the laces (and tuck them inside the shoe to stop tripping over) whilst in the queue meaning when I actually get to the front it's just a matter of slipping them off.  Then at the end I put them back on and do the same with the laces to walk to a chair - there are usually plenty nearby - to put them back on.
If there's no queue you can take your time about it without feeling guilty, although that's a rare occurrence.
Answer: Some boots have a zipper along the side that allows you to put them on/take them off very quickly and easily... I wish I knew this earlier myself as I have a very similar problem with my feet.
Answer: If you sign up for TSA Precheck or Global Entry, you don't have to remove your shoes unless they set off the metal detector.
So as long as you don't have steel toed boots, you should be ok.
Comment: This only works where TSA precheck and Global Entry exists. So not in most of the world. Maybe not everywhere in the USA either.


Creating a 2D skeleton animation system for use with Panda3D

Question: Hey. I want to be able to create a system for 2D skeletal animation in my game. I'm using panda3d as my game engine. I'd like to be able to make simple bone structures and skin them with my sprites. I would prefer to do this with straight code and algorithms, but if I have to use a 3D modeler or something, then I can try to (I didn't do a great job last time I tried using Blender... >.<)
Answer: Not really sure about panda3d, but I am pretty sure you need to start thinking about the algorithms and structure / pattern of making bones then moving them, then skinning them with your sprites.
Once these concepts are strong in your mind, you should then apply them to panda3d (what ever language / scripting it uses) or look up specific panda3d existing 2d animation systems using bones.
Similar to - how to learn 2d animation
How to learn 2d animation?


Is there a custom not to eat roasted chicken at the Seder?

Question: Does the custom to refrain from eating roasted meat at the Seder extend to chicken, turkey, and any other fowl one might serve roasted?
Comment: Such is my family's practice.
Comment: Related: http://judaism.stackexchange.com/q/629/5
Comment: We serve a one-pot stew (potatoes, meat, vegetables) which stays hot until you reach the point of the meal and does not require complex activities from my wife who also wants to hear the hagodo.
Answer: Shulchan Aruch (OC 476:2) writes that those who have the custom not to eat roasted meat on the Seder nights refrain from eating any type of meat that requires slaughtering,  including chicken.  Although the Korban Pesach could not be offered from such meat,  we are still concerned people may come to permit other types of roast.  However fish meat is permitted. (Shulchan Aruch Harav :3)
Answer: In this shiur 49 minutes in he explains it:
http://www.torahanytime.com/scripts/media.php?file=media/Rabbi/Yosef_Viener/2010-03-14/Halachot_Pesach/Rabbi__Yossi_Viener__Halachot_Pesach__2010-03-14.wmv
He even quotes that the OU who he was a mashgiach for at some point and the argument he had based on it
Comment: Can you summarize what he says?


Gel electrophoresis after RNAse treatment

Question:
I do not understand how to solve this question. I know that RNAse will cut smaller pieces of RNA.
The answer given is A
Answer: The question is a bit vague in some important parts, so I'll have to make a few assumptions about what the authors likely meant.
RNAses are enzymes that degrade RNA. There are a few different ones that lead to different kinds of degradation. The type that you would use in an experiment like this is an RNAse that completely degrades RNA. The purpose of this is to be able to distinguish RNA from DNA. So whatever is left after the RNAse treatment is DNA, and the bands that vanished are RNA.
If you isolate nucleic acids from liver, the major DNA part would be genomic DNA. The major RNA components would be mRNA and rRNA. Genomic DNA is huge compared to mRNA and rRNA. In gel electrophoresis of nucleic acids, the bands that move further are smaller nucleic acids, and the bands that move less far are larger nucleic acids. So the band on the left in your example is likely genomic DNA, and the band to the right is mRNA or rRNA. After RNAse digestion only the left band should remain, which is answer A.
Answer: RNA can fold and will therefore migrate faster than DNA. So it shows up as the band which is towards the positive front. After RNAse treatment you'll lose that band. So the answer is A
Comment: Adding to that: A lot of RNAs are relatively small and migrate faster than a genomic DNA prep.


What's the function that SGD takes to calculate the gradient?

Question: I'm struggling to fully understand the stochastic gradient descent algorithm.
I know that gradient descent allows you to find the local minimum of a function. What I don't know is what exactly that function IS.
More specifically, the algorithm should work by initializing the network with random weights. Then, if I'm not mistaken, it forward-propagates $n$ times (where $n$ is the mini-batch size). At this point, I've no idea about what function should I search for, with over hundreds of neurons each having hundreds of parameters.
Answer: Welcome to AI Stack exchange!
You're right, as the network is initialised randomly, the resultant function is essentially impossible to get your head around. This is because most of the time the network has >4 dimensions (4 can be graphed with some effort and a lot of color), and as such is literally beyond human comprehension via graphing.
So what do we do? Well, conveniently, it is possible to find the gradient of segments of a function, without having to know the entirety of the function itself (it's worth noting that it actually is possible to find the resultant function and with a lot of effort find it's derivative. This proves to be much more work than it's worth though, as we don't need the general derivative that tells us what the gradient is for whatever input we give it, we only need the derivative at the specific input we just fed through the network).
This might be hard to understand, but if you're familiar with the chain rule, it might make a bit more sense. The chain rule essentially allows you to split a function into components, and find the gradient of those specific components. By combining all of that, you end up with some nice gradients at each weight/bias with respect to the loss function. Take the negative of the gradient, and you now have the change required to decrease the loss function.
This is obviously quite hard to understand without an example, so here's the best one I've ever found, that helped me very much.
Also, as a side note, the whole mini batch thing is used to minimise catastrophic forgetting (where the network begins to "unlearn" old inputs). To deal with minibatchs, what you do is take input individually, then find the gradient for all weights and bias' for that specific input and remember the changes you want to make. Do that for all inputs in the minibatch, then finally add all the changes together to get the resultant best change  for each weight and bias. Only then do you update the weights and bias'.
Let me know if you have any further questions
Answer:
I know that gradient descent allows you to find the local minimum of a function. What I don't know is what exactly that function IS.

It's usually called the loss function (and, in general, objective function) and often denoted as $\mathcal{L}$ or $L$ (or something like that, i.e. it is not really important how you denote it). The specific function used as a loss function depends on the problem (ask another question if you want to know the details). For example, in the case of regression, the loss function may be the mean squared error. In classification, the loss function may be the cross-entropy. However, the most important thing to note is that the loss function depends on the parameters of the neural network (NN), so you can differentiate it with respect to the parameters of the NN (i.e. you can take the partial derivative of the loss function with respect to each of the parameters of the NN).
Let's take the example of the mean squared error function, which is defined as
$$
\mathcal{L}(\boldsymbol{\theta}) ={\frac {1}{n}}\sum _{i=1}^{n}(y_i-f_{\boldsymbol{\theta}}(x_i))^{2}.
$$
where $n$ is the number of training examples used (the batch size), $y_i$ is the true class (or target) of the input example $x_i$ and $f(x_i)$ is the prediction of the neural network $f_{\boldsymbol{\theta}}$ with parameters (or weights) $\boldsymbol{\theta} = [\theta_i, \dots, \theta_M] \in \mathbb{R}^M$, where $M$ is the number of parameters.
Given the loss function $\mathcal{L}(\boldsymbol{\theta})$, we can now take the derivative of $\mathcal{L}$, with respect to $\boldsymbol{\theta}$, using the famous back-propagation (BP) algorithm, which essentially applies the chain rule of calculus. The BP algorithm produces the gradient of the loss function $\mathcal{L}(\boldsymbol{\theta})$. The gradient can be denoted as $\nabla \mathcal{L}(\boldsymbol{\theta})$ and it contains the partial derivatives of $\mathcal{L}(\boldsymbol{\theta})$ with respect to each parameter $\theta_i$, that is, $\nabla \mathcal{L}(\boldsymbol{\theta}) = \left[ \frac{\partial \mathcal{L}(\boldsymbol{\theta})}{\partial \theta_i}, \dots, \frac{\partial \mathcal{L}(\boldsymbol{\theta})}{\partial \theta_M} \right] \in \mathbb{R}^M$. (If you want to know the details of the back-propagation algorithm, you should ask another question, but make sure you get informed first, because it may not be easy to fully explain it in an answer.)
Afterward, we just apply the gradient descent step
$$
\boldsymbol{\theta} \leftarrow \boldsymbol{\theta} - \gamma \nabla \mathcal{L}(\boldsymbol{\theta})
$$
where $\gamma \in \mathbb{R}$ is often called the learning rate and is used to weight the contribution of the gradient $\nabla \mathcal{L}(\boldsymbol{\theta})$ to the new values of the parameters, and $\leftarrow$ represents an assignment (like in programming).
It is worth emphasizing that both $\boldsymbol{\theta}$ and $\nabla \mathcal{L}(\boldsymbol{\theta})$ are vectors and have the same dimensionality ($M$).
Have also a look at this answer where I explain the difference between gradient descent and stochastic gradient descent.
Comment: @NeilSlater Actually, this answer really helped me out xD. I was confused because I didn't even know what to look for, since I didn't understand the learning algorithm in general, but guess what, I just got a clear explanation about that! ;D
I figured out that the "missing piece" was the backpropagation, wich "connects" the loss function to the actual gradient.

Now, I only need to read this answer over, over and over so that it gets stuck in my head forever. Thanks :D
Comment: The OP is not actually asking about the loss function, but about the target function. That's a difference in perspective, I don't see anything factually wrong in this answer, but I think it doesn't address the question as phrased (whether that is OP's intent of course is a different matter). The loss function measures the difference at a set of discrete points, between the target function and the current function that the NN produces. If you combine your and Recessive's answers you get the full picture, which may help the OP.
Comment: @NeilSlater My answer addresses this sentence _"I know that gradient descent allows you to find the local minimum of a function. What I don't know is what exactly that function IS"_.
Comment: Ah, sorry, the OP actually asks about *both* and is confused. because they also say  *at this point, I've no idea about what function should I search for*. the function that is "searched for" is the target function. I think it would help the OP if you addressed the difference
Comment: @NeilSlater Don't worry. Maybe I should have clarified which part of the post I was addressing. I've just edited my answer to do that ;)
Answer: After I've learned a little bit more about the topic, I think I figured out the exact sequence of the algorithm. So, here's my own answer. Please, correct me if I'm wrong.

Give an input, forward-propagate it, and generate an output
For each output neuron:
  for each weight connected to the neuron:
      Given the function C = f(w) (which represents the cost in function to the weight value), calculate the derivative of that function at the point where  the current weight actually is)
Calculate the actual derivative of all the weights by combining all the partial derivatives in respect to the weight: now you have a gradient of the weights
Repeat this process to calculate the gradient for each of the batch elements. If you have a batch size of 8, then you'll have 8 gradients.
Find the average gradient ((gradient_1+gradient2+gradient3...)/n_gradients)
Move the weights of that gradient

Am I right? How does this apply to deeper layers?
Comment: @nbro I'm asking for your greatness :)
Comment: Thanks for the compliment. I also try to do my best :) Your answer seems roughly correct, but I am not sure why you distinguish the weights connected to the output neurons from the other weights. Anyway, if you have a batch of size 8 (or any other number), you will not compute the gradient with respect to each element of the batch, sum these gradients and then divide by 8.
Comment: Instead, you'll compute the loss with these 8 elements (see the loss function I defined in my answer), then compute a single gradient (which is often called a "stochastic estimate" of the actual gradient, where, by "actual gradient", I mean a gradient computed with all elements of the dataset). How do you compute it? You just take the derivative of the loss function (I defined in my answer) with respect to each parameter of the network. Try to take the derivative of that loss function with respect to one parameter of the network, for a simple network. You will understand better the process!
Comment: Then I suggest you try to implement a basic version of a simple feed-forward neural network (e.g. with 1 or 2 hidden layers), then implement a basic version of back-propagation and gradient descent to train this network. You will understand all the details after having implemented it. See these implementations [https://github.com/mnielsen/neural-networks-and-deep-learning](https://github.com/mnielsen/neural-networks-and-deep-learning). I think they may be useful ;)


Boxplot IQR and confidence interval

Question: Hi
Just a short question. How are the IQR of the boxplot related to the confidence interval of a sample? Is the IQR actually the 50% confidence interval?
Answer: First, the interquartile range (IQR) is the difference between the third and first quartiles, which is a single number, not an interval.
The interval $(Q_{1},Q_{3})$ might be considered a 50% confidence interval, but it's not a 50% confidence interval for the mean that you'd get from any of the usual formulas.
Comment: Saying this "might be considered a 50% confidence interval" makes no sense at all.  I've expanded on this in another answer below.
Answer: My answer didn't seem to score any points with anyone, and rdchat's answer is lousy, so let's look more closely.
Suppose $X_1,\dots,X_n$ are an i.i.d. sample from a normally distributed population with unknown mean $\mu$ and unknown variance $\sigma^2$, and we seek a confidence interval for the population mean.  As usual, let $\overline{X} = \left(X_1 + \cdots + X_n\right)/n$ be the sample mean and $S^2 = 1/(n-1)\sum_{i=1}^n (X_i - \overline{X})^2$ be the (unbiased) sample variance.  (BTW, unbiasedness is overrated.  Everybody knows that, except some non-statisticians.  Apparently there are lots of those.)
Now
$$
\frac{\overline{X} - \mu}{\sigma/\sqrt{n}}
$$
is normally distributed with mean 0 and variance 1, and
$$
\frac{\overline{X} - \mu}{S/\sqrt{n}}
$$
has a Student's t-distribution with $n-1$ degrees of freedom (called "Student's" because it's named after William Sealey Gosset, of course---and some of the content of this forum makes one suspect that a lot of people here don't know that standard bit of folklore).  Go to the table and look up the value of $A_n$ for which
$$
\Pr\left( -A_n < \frac{\overline{X} - \mu}{S/\sqrt{n}} < A_n \right) = \frac{1}{2},
$$
or in other words
$$
\Pr\left(\overline{X} - A_n \frac{S}{\sqrt{n}} < \mu < \overline{X} + A_n \frac{S}{\sqrt{n}}\right) = \frac{1}{2}.
$$
Then
$$
\overline{X} \pm A_n \frac{S}{\sqrt{n}}
$$
are the endpoints of a 50% confidence interval for $\mu$.
Important point: The length of the confidence interval goes to 0 as the sample size increases, since $\sqrt{n}$ is in the denominator (and $A_n$ approaches the value one would get for the normal distribution rather than for Student's distribution).  But the sample quartiles do not get closer together in the limit as $n$ grows, since ("almost surely") they approach the population quartiles.
So the answer is NO.
Answer: You'd hope that as the sample size grows the 50% confidence interval for a location parameter would shrink whereas the first and third quartiles of the sample would approach those of the population.  So no, that's not a 50% confidence interval except in special cases, e.g.  when the sample size is 2.

Boxplot IQR and confidence interval


Lost hole card at showdown?

Question: Texas Hold'em tournament home game.  I get dealt A-s and Q-d mid position.  Saw the flop, called a bet.  Saw the turn, called a bet.  On the river comes the fourth diamond to the board. Me and one other player, I check, he bets.  I look at my hole cards to find one card missing.  The one remaining is the Q-d filling my flush.  Is it legal to continue to play and showdown with only one card?  Where can I find the answer?
Comment: How can you lose a card?  You forfeit the hand.  Many casinos would escort you to out.
Comment: @DannyMahoney I know what it says.
Comment: @paparazzi he said it's a home game... Scotty, sounds like you got bamboozled.
Comment: @Paparazzi oh right, I misinterpreted!
Answer: Rules of poker:

You must protect your own hand at all times. Your cards can be
  protected with your hands, a chip, or other object placed on to p of
  them. If you fail to protect your hand, you have no redress if it
  becomes fouled or the dealer accidentally kills it.

You must keep your cards in view of the dealer.
I get it was just a home game but protect you cards is your responsibility. You deserve to forfeit the hand - even in a home game.
Answer: Home Games often have their own rules partly defined at the start of a night (or otherwise generally known by the players), and partly impromptu. It would be up to the host to resolve this incident. Otherwise: FIND THE CARD!
Sounds like somebody tried to cheat you. But as @Paparazzi said, you are responsible for your cards so you could reasonably expect to be folded out.
Answer: Your hand is dead, you have no claim on the pot. This is a basic rule in all casino poker games.
Answer: The fact is it was a home game and crap happens sometimes. If your other card cannot be found, the fairest way would likely be to look at every other card in the deck and on the table and if the only missing one is the queen of diamonds, you have won. As this is unfair to other players who mucked, this should preferably be done by a person not in the game.
Comment: Yes it would be possible.   And it would be a dead hand.  A player is responsible for protecting their cards.   I saw a hand where a player was all in and her cards got raked because she did not have a protector.  She had to forfeit her hand.
Comment: @Paparazzi And if I recall, she claimed to have had aces to boot!
Comment: @Michael And I believed her.  Imagine if that happened to Phil H.
Comment: "Ok, Phil, we've fired the dealer, shot the floor supervisor, and we are closing the casino.  Are you happy now?  No, we still couldn't retrieve your cards from the muck..."
Comment: "This would have been impossible" - cameras don't stop cards getting mucked or flipped or stolen. Even if they are all being actively monitored at all times, which is not often the case.
Comment: You are all correct and I have edited my answer

Lost hole card at showdown?


Is there a relationship between Free Radicals and Beta Particles?

Question: This question is contingent on my understanding of the two terms in the title. As I was taught, a Free Radical is a reactive (high energy?) valence electron released for stability's sake because it is unpaired. I was taught that a Beta Particle is a high energy and fast moving radioactive positron or electron released to stabilize an atom. If both of these premises are true, is there a relation between the two terms, and if so, what is it?
Comment: Chemistry electrons are ~1eV, betas are ~1keV.
Comment: A free radical isn't an unpaired electron, it's a species containing one or more unpaired electrons.
Comment: Those sound like they should be common names for departmental intramural softball summer league teams - the Free Radicals and the Beta Particles. I'd bet the first is actually pretty common for Chemistry students, the second less so amongst Physics students.
Comment: not directly as most atoms are not radioactive, but indirectly as the electron is energetic enough to form many radicals (and ions) in other molecules.
Answer: There is high-energy in the sense of chemical reactivity, and then there is high energy in the sense of nuclear reactivity. The energy associated with the latter is many orders of magnitude greater than the energy associated with the former, so that there is generally no direct interaction between the two (where the free radical is chemically reactive, and the beta particle arises from nuclear reactivity).
A free radical is a chemical species, whose electron configuration is such that it is highly reactive towards other chemical species. However, this energy is far too low to affect any nuclear reactivity.
A beta particle is a high-energy electron or positron emitted by the radioactive decay of an atomic nucleus. As these particles are emitted from the nucleus of the atom, the electron configuration (i.e. a free radical) is irrelevant; only the stability/reactivity of the nucleus determines whether an atom will emit a beta particle, not the chemical species.
If any of this seems incorrect or unclear, please do not hesitate to ask for clarifications in the comments.


Is it necessary to perform a separate ablution before every prayer?

Question: I have searched but didn't get any exact hadiths related to it that more than one prayer can be offer in one ablution or we have to perform a separate ablution for every prayer.
Answer: Yes, praying with the same wudhu is valid. Although, it is Sunnah to perform ablution for every prayer as the Prophet (ﷺ) used to do so.

Narrated 'Amr bin 'Amir:
Anas said, "The Prophet (ﷺ) used to perform ablution for every
  prayer." I asked Anas, "What did you used to do?' Anas replied, "We
  used to pray with the same ablution until we break it with Hadath."
Sahih al-Bukhari 214
Answer: No it is not necessary to perform a separate ablution before every prayer.But if you do separate ablution for every prayer it is more good.
Answer: if you already have wudu then it's not necessary to make another wudu, but it is recommended. As far as you don't make any thing that destroys your wudu. you can offer separate salah with single wudu.
Answer: Ablution is sunnah we are blessed with this before every prayer. But it's not necessary to perform ablution before every prayer if you already have it. But it's good to perform ablution before every prayer if you are on road and any other place where water is not available you can pray with your last performed wadu if it is still you have.
And the other side is that if you are at home and a place where you can easily perform ablution than do it.


How do you setup ssh to authenticate using keys instead of a username / password?

Question: How do you setup ssh to authenticate a user using keys instead of a username / password?
Answer: For each user: they should generate (on their local machine) their keypair using ssh-keygen -t rsa (the rsa can be replaced with dsa or rsa1 too, though those options are not recommended). Then they need to put the contents of their public key (id_rsa.pub) into ~/.ssh/authorized_keys on the server being logged into.
Comment: Don't forget
    chmod 0700 .ssh
    chmod 0600 .ssh/authorized_keys
Comment: Definitely generate the keys this way but then check @Chris Bunch's post regarding "ssh-copy-id". That's the way to transfer your 'id_rsa.pub'.
Comment: The only other thing I would add to this is look at the permissions on the file and directory.
Comment: FWIW, this answer is rather old; most SSH implementations should support newer ed25519 keys and these are ideal.
Answer: I actually prefer ssh-copy-id, a script found on *nix by default (can be put on Mac OS X easily enough as well) that automatically does this for you. From the man page:

ssh-copy-id is a script that uses ssh
  to log into a remote machine
  (presumably using a login password, so
  password authentication should be
  enabled, unless you've done some
  clever use of multiple identities)
It also changes the permissions of the
  remote user's home, ~/.ssh, and
  ~/.ssh/authorized_keys to remove group
  writability (which would otherwise
  prevent you from logging in, if the
  remote sshd has StrictModes set in its
  configuration).
If the -i option is given then the
  identity file (defaults to
  ~/.ssh/identity.pub) is used,
  regardless of whether there are any
  keys in your ssh-agent.
Comment: @Chris Bunch
EVERYONE LOOK OVER HERE!
:) ssh-copy-id is definitely the way to share one's id_rsa.pub
Comment: Cool, I never knew about this... I wrote my own script to do exactly the same thing :-/
Answer: Hum, don't get it. Simply create a key and get started. :) HOWTO
Additionatly you could forbid login via password.
In e.g. /etc/ssh/sshd_config:
PasswordAuthentication no

Comment: And you also need to set UsePAM no   (or configure PAM accordingly). It's amazing how many HOWTOs miss this part out. Failure to do so will result in you still being able to login using a password.
Answer: This is fairly straight-forward to do - there's a simple walkthrough to be found here.
The main points are:

Run ssh-keygen on your machine. This will generate public and private keys for you.
Copy and paste the contents of your public key (likely in ~/.ssh/id_rsa.pub) in to ~/.ssh/authorized_keys on the remote machine.

It's important to remember that this will give anyone who has access to the private key on your machine the same access to the remote machine, so when generating the key pair you may choose to enter a password here for extra security.
Comment: I recommend cut-and-paste instead of copying. An authorized_keys file can contain multiple keys, and you don't want to clobber the other keys already in there.
Comment: My favorite walkthrough has been consigned to the Wayback Machine: http://web.archive.org/web/20061103161446/http://www.justenoughlinux.com/2004/04/14/scp_without_passwords.html
Comment: @Chris oops - I did mean to copy it in to the file rather than over-write! Answer updated now to clarify
Answer: For Windows users to setup putty

http://www.howtoforge.com/ssh_key_based_logins_putty
Answer: To summarize what others have said, setting up SSH keys is easy and invaluable.
On the machine that you will be SSHing from you need to generate your key pair:
claudius:~$ ssh-keygen
Generating public/private rsa key pair.
Enter file in which to save the key (/home/dinomite/.ssh/id_rsa): <ENTER>
Enter passphrase (empty for no passphrase): <PASSPHRASE>
Enter same passphrase again: <PASSPHRASE>
Your identification has been saved in /home/dinomite/.ssh/id_rsa.
Your public key has been saved in /home/dinomite/.ssh/id_rsa.pub.
The key fingerprint is:
a3:93:8c:27:15:67:fa:9f:5d:42:3a:bb:9d:db:93:db dinomite@claudius

Just hit enter where noted and enter a passphrase when prompted - ideally this is different from your regular login password on both the current host and the ones you will be SSHing to.
Next, you need to copy the key you just generated to the host that you want to SSH to.  Most Linux distributions have a tool ssh-copy-id for doing this:
claudius:~$ ssh-copy-id caligula.dinomite.net
Now try logging into the machine, with "ssh 'caligula.dinomite.net'", and check in:

  .ssh/authorized_keys

to make sure we haven't added extra keys that you weren't expecting.

If your distribution doesn't have that, then you should copy the key to the destination host and add it to the (possibly existing) .ssh/authorized_keys file:
claudius:~$ scp .ssh/id_dsa.pub caligula.dinomite.net:
id_dsa.pub                                    100% 1119     1.1KB/s   00:00
claudius:~$ ssh caligula.dinomite.net
Last login: Sat May  9 10:32:30 2009 from claudius.csh.rit.edu
Caligula:~$ cat id_dsa.pub >> .ssh/authorized_keys

Finally, to gain the maximum benefit out of SSH keys, you will want to run an SSH agent.  If you use a desktop environment (Gnome, KDE, etc.) then just logging out and back in will start an SSH agent for you.  If not, you can add the following to your shell RC file (.bashrc, .profile, etc.):
SSHAGENT=/usr/bin/ssh-agent
SSHAGENTARGS="-s"
if [ -z "$SSH_AUTH_SOCK" -a -x "$SSHAGENT" ]; then
    eval `$SSHAGENT $SSHAGENTARGS`
trap "kill $SSH_AGENT_PID" 0
fi

Answer: There is good advice on here, so I won't repeat it. Once you get one server set up to allow you to sign on with keys, you can setup others to do the same with this one liner:
remote=server1 server2 server3 server4
for r in $remote; do echo connecting to $r; tar czf - ./.ssh/id*.pub ./.ssh/authorized_keys2 ./.ssh/config | ssh $r "tar zxf -; chmod 700 .ssh" ; done

Just cd to your home directory, define the variable remote as one or many server names and do a bunch at once. The password it asks for will be your ssh password for the remote server. You can of course use a simplified version without the for-loop:
tar czf - ./.ssh/id*.pub ./.ssh/authorized_keys2 ./.ssh/config | ssh YOUR_SERVER_NAME_HERE "tar ztvf -; chmod 700 .ssh"

REMEMBER: Only copy over your public keys. You don't want your private keys sitting out on some server where anyone with sudo can copy them and brute force your passphrase.
Answer: This is intended as a checklist.  If one follows it point-by-point, the most common gotchas to passwordless logins should be covered.  Most of these points are mentioned elsewhere; this is an aggregation.
There must be a ~/.ssh directory chmod 700 on each machine under the account that will originate or receive the connections.
The (private) key must be generated without a passphrase, or an agent can be started which will hold a decrypted version of a passphrase-bearing key for clients to use.  Start the agent with ssh-agent $SHELL .  It's the $SHELL part that took me a while to find.  See the man page as there are multifarious details if you want to use an agent.
Don't forget that by default weak (<2048 bit DSA) keys are not accepted by recent versions of sshd.
The following must be done on the client-side machine to originate a connection.

Your private key must be placed in ~/.ssh/id_rsa or ~/.ssh/id_dsa as appropriate.  You may use another name, but then it must be included on a -i option on the ssh command on the originating machine to explicitly indicate the private key.
Your private key must be chmod 600.
Check that your home folder is chmod 700.

Now for allowing a machine to receive a request.  A common model is where an admin is giving you access to a machine you don't own (like shared web hosting).  Therefore, the idea with ssh is that you offer your public key to whomever is giving you the account.  That's why you generally don't put private keys on the machine receiving requests.  But, if you want this machine to do outgoing ssh as well, then you must treat is as an originating machine with the steps above.

Your public key must be placed in a file called ~/.ssh/authorized_keys under the account that will receive the connections.  You may place other keys that are allowed to connect via this account in here as well.  A particularly tricky thing if you are in vi and pasting the key into the file from the paste buffer in PuTTY is this:  the key starts with a "ssh-".  If you are not in insert mode, the first "s" will put vi in insert mode and the rest of the key will look just fine.  But you'll be missing an "s" at the beginning of the key.  It took days for me to find that.
I like to chmod 600 ~/.ssh/authorized_keys.  It must be at least g-w.
Now, you must have the host fingerprint added to the cache.  Go to machine A, and ssh to machine B manually.  The first time, you will get a query like "Do you want to add . . . to the host key cache?".  If you are trying to get automation (such as a script) to use this login, you must ensure that the ssh client being used by the automation will not get this prompt.
Answer: As others have said, your users should make keypairs for themselves on their client machines with ssh-keygen and add their public key to ~/.ssh/authorized_keys on the machine they want to log into.
For more detailed information though, I highly recommend SSH, The Secure Shell.


Free & easy blog platform with option to let others see it only with a password, no need to register

Question: I liked the ideas of tumblr, especially that one can upload videos (although altogether the site didn't work very smoothly for me) but there others only get access with password and registration.
Comment: What exactly do you mean by "others only get access with password and registration". Is it to view posts? Because if that is the case, then tumblr lets you view other people's posts without registering. Or is it to post stories without being the owner of the blog?
Comment: Hi Alex, Thanks for asking. As far as I saw tumblr only lets others see password protected blogs if they also register. Wix allows to share the password so they can see it without registration but there as far as I saw you cannot upload videos (only via youtube or vimeo where I think they don't have password a protection option). In my blog others should be able to comment, not necessarily add their own posts (although if that is optional it would be a plus. Another big plus would be an option to allow more different language versions).
Answer: You might try Wordpress (How to Password Protect Your WordPress without User Registration).
A word of caution : As there's a need to install an additional plugin, you will probably need to install it on an owned server/domain (wordpress plate-form will make you pay if you want to install plugins)...but it's free to download and use.
Comment: I already tried installing WordPress, stopped after failing step one of the explanation, and a whole system plus an additional plugin is not really easy to use.
Comment: You're right, you asked for easy :) However, some hosting companies use things on their servers like softaculous. It allows you to install very easily Wordpress, for example.
Comment: He needs to set a proper database to install Wordpress. I don't think the others are easier.


Remove beamer markup

Question: I have a main.book.tex and a main.beamer.tex which then \input the same source files. In those source files, I have a lot of \mode<> designations and generally, a lot of beamer markup -\overlayarea's, \only<>'s, etc.  My problem is that I also want to output to HTML. Now, tex4ht is generally awesome, generally plays nice with beamer and beamerarticle, and I've spend a lot of time customizing it to get it to do what I want. But, I'd like to try other conversion tools (e.g. pandoc) that can't handle beamer markup. Are there any good tools I could run my files through to remove the beamer markup? I've started writing a script to do this, but I thought maybe tex.sx already knows of such tools or has better ideas.
Answer: No, I don't think so.
The best bet -- and probably fastest approach -- is to write some regular expression scripts that remove exactly what you want.
Candidates are sed (http://www.grymoire.com/Unix/Sed.html), Perl (perldoc.perl.org/perlre.html , perldoc.perl.org/perlretut.html), and Python (http://docs.python.org/2/library/re.html).
You can have these scripts run automatically if you incorporate calling them into an automated build system like make or SCons.

Remove beamer markup


Who writes the Dragon Ball Heroes manga?

Question: So now aside the Dragon Ball Super manga aparently there is also a Dragon Ball Heroes manga. Who writes the Dragon Ball Heroes manga? Does Akira Toriyama has any involvement in it?
Answer: Toyotarō (とよたろう) is the author of the spin-off manga Dragon Ball Heroes: Victory Mission, which debuted in the November 2012 issue of V-Jump and the illustrator of the Dragon Ball Super manga version. He is Akira Toriyama's chosen successor.[1]
http://dragonball.wikia.com/wiki/Toyotar%C5%8D
Comment: So the Dragon Ball Heroes manga has the same writer than the Dragon Ball Super manga and Toriyama made some of the character designs. I guess it isnt so "untrue" to Dragon Ball as people states it to be


Export Plots to $\LaTeX$

Question: What is the quickest and best way to export a plot image from Mathematica to a $\LaTeX$ Editor? Is there something quicker than exporting it to an image and then including it in the $\LaTeX$ document?
Comment: Exporting from Mathematica is not the fastest way. Copying and pasting is. You just have to use a LaTeX editor that supports pasting graphics. I have been using LyX for that for years because it does that automatically. I can't even imagine not having that copy-paste functionality.
Comment: does not work with WinEdt
Answer: The absolutely fastest way I know to get high-quality latex output is:

Make sure you use LyX as the editor (http://www.lyx.org/)
In MMA, highlight the plot, select "Copy as ... PDF" from the Edit menu
In Lyx, paste wherever you want, that's it.
The PDF will be saved under a default numbered file name (you can optionally rename it)
Run pdflatex from the View menu

Edit
Copying as PDF may not be available on all platforms - but you asked for the fastest way to export a plot image to a $\LaTeX$ editor, and this is it. My platform is Mac OS X. On other platforms, LyX is also available, but the "Copy As..." function may not offer PDF. Then you have to choose whatever other format that platform offers.
Edit 2: copying complex graphics: 3D plots, contour plots, etc.
As has been noted in this post on $\LaTeX$ and Mathematica, you can no longer rely on EPS as an acceptable file format for exporting graphics, because it can't handle opacity and can't be used in pdflatex workflows.
Unfortunately, this means that answers based on Save As ... LaTeX document are simply not ready for production use at this point, because that method relies on EPS  files.
On the other hand, copying as PDF can also have one problem: the large file size created especially when attempting to convert Graphics3D objects to PDF.
Fortunately, that can be avoided by making sure that Mathematica automatically rasterizes 3D graphics upon export to PDF. There is an export option "AllowRasterization"->True, but I found a method that produces better quality rasterization without setting that option. The reason it's relevant here is that this approach works with copy-and-paste, too. It's described here and here, and I'll just give the recipe below: start the notebook with this initialization:
Map[SetOptions[#,
    Prolog -> {{EdgeForm[], Texture[{{{0, 0, 0, 0}}}],
       Polygon[#, VertexTextureCoordinates -> #] &[{{0, 0}, {1,
          0}, {1, 1}}]}}] &, {Graphics3D, ContourPlot3D,
   ListContourPlot3D, ListPlot3D, Plot3D, ListSurfacePlot3D,
   ListVectorPlot3D, ParametricPlot3D, RegionPlot3D, RevolutionPlot3D,
    SphericalPlot3D, VectorPlot3D}];

Now all exported and copied PDF of 3D graphics will be a wrapper for a print-quality high resolution image instead, and pasting it into LyX works in the blink of an eye.
The list of 3D plot functions in the command above can be extended to include some notoriously unwieldy 2D plot functions as well, e.g., ContourPlot, DensityPlot etc. They have a lot in common with 3D graphics in that they tend to produce huge numbers of polygons to create colored regions or gradients. For my own use, I didn't include these functions in the list above because I prefer to employ a couple of homemade substitutes for these functions that produce rasterized color gradients in their own special way.
Comment: The PDF from the clipboard, as I said. It is automatically saved by LyX as a PDF with the LaTeX document. What happens when you press the paste key is that LyX recognizes when the pasteboard is able to provide a PDF representation of the object to be pasted, and then it writes that representation to a file (it also creates the \includegraphics code, of course).
Comment: What exactly do you paste into LyX?
Comment: Uh... agreed, that sure is straightforward!
Comment: When exporting a 3D graph after initializing the notebook with the command described above, the shading of the 3D plot is lost: instead of gray shading, I get a completely black envelope, useless for a scientific paper...
Comment: @Xavier_B Can you give a simple example? Maybe you just have to add another of the 3D commands to the list run through `SetOptions`...
Answer: I usually Export to hi-res PNG bitmaps for ease of use (there are a number of discussions on how best to export high-quality images on this forum. Take a peek at the right column of this page under "Related"). Personally I like notebooks that do not need any mouse-clicking or any other user interaction to produce output which makes reruns that much more comfortable and and most of all reproducible.
For ease of use when dealing with many different graphics I prepare a notebook for each of these and also generate the LaTeX code for insertion in my document. The graphics get their name from the notebook so you can easily spawn different versions by renaming the notebook.
plot = Plot[Sin[x], {x, 0, 10}]

(*gfxname = StringTake[FileNameSplit[NotebookFileName[]][[-1]], {1, -4}]*)

EDIT: more concise and portable:
gfxname = FileBaseName[NotebookFileName[]]

"2012-05-04_Plot_Export"

Export[gfxname <> ".png", plot];

StringReplace["\\begin{figure}[!htb]\\centering
 \\includegraphics[width=1\\textwidth]{XXX}
 \\caption{Put your caption here.}
 \\label{fig:XXX}
 \\end{figure}
 ", "XXX" -> gfxname]

The resulting output can be copied as plaintext or you might even splice it directly into your document (although this is a bit much for casual use).
\begin{figure}[!htb]\centering
\includegraphics[width=1\textwidth]{2012-05-04_Plot_Export}
\caption{Put your caption here.}
\label{fig:2012-05-04_Plot_Export}
\end{figure}

Comment: @Szabolcs thanks for getting rid of the TeX formatting ;-)
Comment: MathJax will try to interpret the LaTeX it finds, producing these funny boxes
Comment: @YvesKlett can you tell me what do after I've got the plot in Mathematica?
Comment: @Math question is a bit unclear... You can paste the generated text in your TeX document and make sure the generated graphics file is on a path your compiler can find.
Comment: @YvesKlett I asked a similar question here: https://tex.stackexchange.com/questions/601205/how-to-use-a-mathematica-plot-in-latex-as-a-figure
Comment: @YvesKlett can you give a step by step tutorial because I'm not so good with computers!
Answer: If you create a notebook with some plots and then save it as LaTeX, not only will the images all be generated but so will LaTeX code that you can use to include those images.
Comment: +1 We are very coherent this morning - 3 min difference - the irony ;-)
Comment: @Vitaliy Fortunately, I'm going out for the day!
Answer: One way to speed up the workflow is to batch process all your images and even formulas if you have many. Basically do all your work in the Mathematica notebook placing distinct graphics, formulas and text in separate cells. Then choose File > Save As... and pick LaTeX Document (*.tex) from the drop down menu of popped up window. This will produce a set of .EPS files for each of your graphics stored in separate cells and a coherent .TEX file with text, formulas and calls to the .EPS images.
Answer: The way I do this is by creating a directory structure like the following:
project
project/figures

The LaTeX file is in project, the figures are in figures.  I put the notebook(s) used to generate the figures in project as well, but you can make a separate directory for them.
The notebooks start with
SetDirectory@FileNameJoin[{NotebookDirectory[], "figures"}]

and ends with
ResetDirectory[]

The figures are then Exported to PDF files.  Some tips on how to do this effectively are in this thread:

$\LaTeX$ and Mathematica

The key point is that I export all figures to the correct final size, ensuring that the font sizes will be consistent (e.g. in all figures the fonts will be precisely 8 pt big).  (Re-)evaluating the notebook will produce all figures and save them directly into the figure directory.
For the LaTeX part, I use the graphicx package and compile everything with pdflatex. (pdflatex directly supports PDF, PNG and JPEG images.)  In the preamble I include \graphicspath{{./figures/}}, so I can avoid specifying the full figure path.  I include the figures using \includegraphics{figname}, without writing the file extension.  This way, if later it turns out that everything needs to be converted to EPS from PDF (figname.pdf --> figname.eps), I won't need to modify the LaTeX source, I can simply switch from compiling with pdflatex to compiling with latex.
If some figures need to be post-processed manually using some illustration software, I export them to a separate directory, then copy the final result manually.  I keep all figures under version control (in addition to the figure notebook), in case re-evaluating the figure code will overwrite and break something.
Comment: Plus, pdflatex also nicely works together with PNGs and JPGs without the need to add suffixes in the document source.
Answer: I just figured out the following workaround imitating the psfrag convenience while avoiding intense programming or additional software:

Create a new PlotTheme as described here. It should contain the Latex fonts i.e. FontFamily->"CMU Serif", the font size of the document to be created, i.e. FontSize->11 and the final size of the plot via ImageSize->425. The latter is necessary for reproducible font sizes. My result looks like this:
Themes`AddThemeRules["Export",
DefaultPlotStyle->Thread@Directive[ColorData[97,"ColorList"], Thick],
Frame ->True, Background -> None, LabelStyle -> {FontSize->11,
FontFamily -> "CMU Serif"}, ImageSize -> 425, PlotMarkers -> {Automatic, Small}];

Use the new PlotTheme on the figure like so: Plot[...,PlotTheme->"MyTheme"] and export as EPS
Import into Latex with size of 100%.

I ended up creating a small version with 212pt Image Size and a larger for full-page plots of 425pt. Also, I made a package to have them ready at every session.
This imitates psfrag in the way that if the document font size or -style changes, the plots can be redrawn quickly by simply changing the custom themes and exporting again.
This is not a proper solution to the problem, but an easy workaround, which should be sufficient for most cases. It might not be enough for a journal article, though:

In general it is a shame that Mathematica cannot separate graphics and text upon export. Matlab and most other Software packages have much better latex export functionalities. Maybe it is just a marketing thing - making it hard to avoid the Mathematica style. In any case a much-needed feature for v11!

Export Plots to $\LaTeX$


Find the area of the region inside the limaçon

Question: I'm struggling to figure out the answer to this:
Find the area of the region inside the limaçon, $r=3 + \sin(\theta)$
Could someone please help me out?
Answer: Draw a picture. We use the standard formula for area in polar coordinates. In principle there could be a problem with the interval of integration, but here there is no problem, because $3+\sin\theta$ is always positive. So our area is
$$\int_0^{2\pi}\frac{1}{2}(3+\sin\theta)^2\,d\theta.$$
For the details, expand. The integral of $\frac{9}{2}$ is easy. For the "middle" term, the integral is easily $0$. Finally, we need to deal with $\int_0^{2\pi}\frac{1}{2}\sin^2\theta\,d\theta$. There are many ways to do this. One of them is to use $\cos2\theta=1-2\sin^2\theta$. Another way is to use symmetry, and note that the integral over our interval of $\cos^2\theta$ is the same as the integral of $\sin^2\theta$. But the sum of these integrals is the integral of $1$.
Answer: If you've seen multiple integrals, calculating this area is relatively simple and doesn't require memorizing a single-integral formula. You just integrate $$\int_{\theta_{min}}^{\theta_{max}}\int_{r_{min}}^{r_{max}}rdrd\theta$$ with the limits of integration being the bounds of your function. Setting this up, we get $$\int_{0}^{2\pi}\int_{0}^{3+sin(\theta)}rdrd\theta$$ First we integrate with respect to $r$, and get $$\int_{0}^{2\pi}\frac{(3+sin(\theta))^2}{2}d\theta$$
Now we pull out the $\frac{1}{2}$ and expand to get $$\frac{1}{2}\int_0^{2\pi}9+6sin(\theta)+sin(\theta)^2d\theta$$
Using integration techniques, we simply this integral and find that $A=\frac{19\pi}{2}$
Comment: I know this was posted almost four years ago, but--thank you! This is exactly what I needed. :)
Comment: Same. 11 years later.  Thank you!
Answer: Recall the formula for finding an area integral in polar coordinates is given by
$$\frac{1}{2}\int_{\alpha}^{\beta}r(\theta)^2\ d\theta$$
The curve is traced from $\alpha = 0$ to $\beta = 2\pi$. We then have
$$A = \frac{1}{2}\int_{0}^{2\pi}\left(3 + \sin(\theta)\right)^2\ d\theta$$
This integral is quite standard so I leave you to finish it.
Answer: It would help to plot it first.

Now use this formula $$A = \frac{1}{2}\int_{\alpha}^{\beta}f(\theta)^2\ d\theta$$
From the picture we see that the curve runs from $0$ to $2\pi$
$$A = \frac{1}{2}\int_{0}^{2\pi}(3 + \sin(\theta))^2\ d\theta = \frac{19\pi}{2}$$ The computation is trivial and it's something you can look up on WolframAlpha if you aren't sure


Why does Hinduism not encourage converting people of other religion?

Question: I have asked many people but haven't got a satisfactory answer. Not only Hindus reluctant to convert other people, but also it is extremely difficult for people from other religion to become Hindu. Why is that?
Comment: Comments are not for extended discussion; this conversation has been [moved to chat](http://chat.stackexchange.com/rooms/58821/discussion-on-question-by-bibaswann-bandyopadhyay-why-does-hinduism-not-encourag).
Comment: Go through this question: https://hinduism.stackexchange.com/questions/407/is-it-true-that-one-can-not-convert-to-hinduism-from-any-other-religion-or-vice/414#414
Answer: I have found the following explanation by Swami Tapasyananda useful as to why Hinduism does not proselytize.

…Worship of a God who is not also the Absolute is idolatry, and a mere
  Absolute, who is characterless and is irresponsive, is not better than
  matter. The Vedanta accepts the Supreme as both Personal and
  Impersonal. When the votary in the course of his spiritual development
  becomes de-personalized on achieving the elimination of his ego-based
  body-mind, he will be able to understand the true Impersonal. Till
  then, that is, so long as he is a person, the Impersonal and the
  Absolute can only mean for him a Personal Being who is much more than
  what he, a person, has grasped or can grasp of Him. To illustrate, the
  Impersonal-Personal Divine of the Vedanta is the ocean and the God of
  adoration of the devotee is like a big field or backwater into which
  the water of that ocean has flowed. The many deities that form the
  object of worship of Vedantism are like these tanks and backwaters in
  the analogy. They are so many manifestations of the
  Personal-Impersonal Sat-chit-ananda in the thought structures of those
  who adore Him, or are forms adopted by Him for the achievement of
  cosmic purposes in his world-play. The worship of these forms with an
  understanding of the infinitude that informs their finitude ...... is
  the only form of true worship that the human mind is capable of, so
  long as man remains a limited person. The other ideas of the Divine
  which Semitic religions hold – their so called boasted monotheism – is
  only a form of disguised idolatry; for when it is said that Jehovah is
  a jealous God, or that there is no God but Allah, it is obvious that
  the Supreme Being is being identified as an exclusive individual and
  not as an expression of an Infinite Being in terms of the human mind.
  When the link with the Infinite is forgotten, a Deity, whether it is a
  monotheistic entity or a polytheistic being becomes a mere idol. Real
  worship of the Supreme Being is possible only when the principle of
  Vedantic polytheism is understood – that principle being the perception of
  the Infinite Personal-Impersonal Being through a limited manifestation
  of Him.
A Vedantic Deity is never aggressive, demanding the overthrow of other deities. But, a monotheistic Deity, always a jealous God, cannot
  tolerate another Deity.As Toynbee has pointed out, the monotheistic
  Deity of the Semitics is only an apotheosis of the group or tribal
  consciousness of certain people, a sentiment that held together
  societies before nationalism took its place. Just as the nationalistic
  patriotism is eager to absorb all other countries, that form of group
  consciousness masquerading as monotheism wants to supplant all other
  religions and establish its Deity in their sanctuaries. Proselytism,
  for which many religions stand but which has no place in the Vedantic
  scheme, is the consequence of the Infinite Being but a
  personalisation of the group consciousness of a people.
The principle enunciated above in regard to Deities is applicable also
  to worship of God in holy images, which critics, who are practicing
  real idolatry, have stigmatised as idolatry. The Vedantin's God is not
  an individual as the Semite's. He is the Universal Spirit who has
  manifested as All-Nature. He is one with all, and if a person with
  faith wants to see Him anywhere, He is present there. Like water
  running all through the ground, He is everywhere; and if the well of
  faith is dug, He becomes available for worship. A holy image is thus a
  point at which His real presence is available for imperfect man to
  apprehend and commune with. It is not a mere means for practising
  concentration as some apologists say. It is much more. It is a point
  of real communion with the Divine when the eye of faith reveals Him as
  accepting the worship and offering made by the devotee. It is in this
  spirit that all great sages and saviours of India, down to Bhagavan
  Sri Ramakrishna, have seen and adored the Holy Images. Its practice is
  one of the most excellent and necessary aids for the vast majority of
  men to gradually rise in the spiritual scale. The Divine presence is
  made concrete, and prayers and adoration made meaningful to those men
  who cannot dive into the depths of consciousness by meditation and
  introspection and commune with the subtle Spirit as the Inner Pervader
  within. It is therefore a necessary step in practising religion as an
  experience instead of reducing it to an expression of conformity with
  a dogmatic creed or adherence to some formal code of conduct and
  rituals.

[Swami Tapasyananda's introductory remarks in 'A Primer of Hinduism' by D.S.Sarma]
Answer: It is very misunderstood that Hinduism/Sanatan dharma does not encourage/discourage conversion.

During ancient times Hinduism used to engulf other religions as sects inside its own. Various tribal /regional gods etc. usurped were denoted as avataras of mainline Hindu Gods. Hence, entire religions itself (not just followers) were engulfed (converted) by Hinduism
The Aversion of conversion in hinduism, which you are talking of, is very prevalent when you talk of hinduism as understood in its "Brahminism" sense (ie, the local pundit, pujari as they perceive Hinduism). In this arena, the Casteism (almost racism kind of ideology) and Pauranic conventions prevails more than the base philosophical principles of hinduism/sanatan dharma. So in this sense, yes - it is not encouraged.
But when you go deeper, then you will find that Casteist tendencies which encourage people to keep their blood lines pure (by not intermarrying etc.), they will reasonably be uncomfortable with new bloodlines coming inside. So they will try to discourage it.
But when you analyze it from canonical text (not just any scriptures), then Casteism (Racism) is not part of canonical hindu religion's principles.
Hence, Arya samaj sect which profoundly says that it is based only on vedas, is very easy to easily convert from other religions to Arya Samaj. Because, it has no connection with these Pauranic tendencies which were not part of Shruti.
Also, ISKCON sect which takes only Vedas, Bhagvad purana etc. as canonical text; in this also you can easily convert from other religions to Hinduism. ISKCON people actively spead gospel of krishna.
in philosophical schools like Advaita etc. (like Vivekananda's many foreign converted disciples and like Aurobindo's foreigners converted disciples) even 100 years ago had no problem in getting converted from other religions.

Conclusion: Hinduism is not monolithic sect. Hence:

In few sects and prevalent brahminism (casteist tendencies more prominent) followers of hinduism only discourage peole from other religion converting to hinduism.
But other sects of hinduism have no problem in it.
So having a view on conversion is a sectarian issue. Conversion is not part of central focus of Hinduism, i.e. Central hinduism core has no encouragement/discouragement on this, i.e. it is more concerned about way of living. Sects down the below have their own views regarding conversions.
Comment: You should cite sources.
Comment: also related: see https://hinduism.stackexchange.com/a/26326/13287 and see https://hinduism.stackexchange.com/a/26319/13287 and see https://hinduism.stackexchange.com/a/26324/13287 and see https://hinduism.stackexchange.com/a/24722/13287 and see https://hinduism.stackexchange.com/a/24623/13287 and see https://hinduism.stackexchange.com/a/26301/13287


Keyboard shortcut to sign out of Gmail

Question: Is there a keyboard shortcut that will sign me out of Gmail?
Comment: Can you tell what operating system/browser do you use ?
Comment: Windows 7 - Google Chrome
Answer: Unfortunately, there isn't a shortcut to use in Gmail for signing out.
But you can copy the sign out link https://mail.google.com/mail/?logout&hl=en and assign a keyboard shortcut to it, or add it to your bookmarks.
Example:
Assuming you are using Google Chrome, use ClickLess, a Chrome extension, to assign a shortcut for the link of sign out, which is mentioned above.
Go to the options of this extension and add the shortcut.
Now whenever you need to sign out. Use Ctrl+Alt+S, a small windows will pop out, press now s which is the shortcut key for signing out from Gmail.
Comment: Okay. That sounds like a good workaround. Thanks for your answer.
Comment: It really does work!
Answer: If you use Opera, add the above mentioned URI to one of your speed dials (first 9). Then use Ctrl+N (where N = digit 1-9) when you are on Gmail to sign out.
I added this on my 1st speed dial, so now I can easily sign out by hitting Ctrl+1.
Comment: Please fully read the question, comments, and already provided answers prior to  adding a new answer, especially to old questions.  Back in Aug 2011 almost a year before this post the asker stated that this was in Chrome.
Answer: A trick better than shortcut key is just to paste this link on the address bar to sign out...  ***

https://mail.google.com/mail/?logout&hl=en

Keyboard shortcut to sign out of Gmail


Luggage and customs for international layover in Toronoto

Question: I will be traveling from Chicago to Toronto on United and then on to Halifax via Canada Air.  My questions is do I have to go to baggage claim in Toronto to pick up bags and then recheck my bags?  I only have 1 hour and 7 minutes between flights.  So a little concerned that I can't accomplish everything (baggage, customs, etc.) in that time frame.
Answer: The definitive answer is waiting for you at http://www.torontopearson.com/Connecting.aspx

Assuming you meant Air Canada (a United partner) Yes, you will need your baggage while you clear Canadian customs, and then you will recheck it.
Comment: Note that as of late 2015, the luggage procedures changed for connecting flights at Pearson (at least those coming from the US and ending in Canada);  you no longer need to pick up and re-check your bags.
Answer: Having connected from the US to Canada via Toronto many times, I would be nervous about that connection if I were you.

The walks will be long.  This is particularly true if your plane is arriving in Toronto from a smaller U.S. airport, which flights use small commuter jets and turboprops.  These planes arrive at Gates F84-99, which is a small section of the airport (essentially a long hallway, with minimal services) that is well-separated from the rest of Terminal 1.  There is a sign at the beginning of this section that says something like "7 minute walk from this point to Gate F99;  no shops beyond this point."  Flights from larger airports (including Chicago) usually use larger planes, which generally use the gates closer to the main part of the terminal.
The amount of time you'll need to wait in line for Customs is highly variable.  The last time I was there I sailed right through, but you can also stand in line for a good 20 minutes if you arrive right after a couple of big jumbo jets.
After you talk to the Canada Customs officer, you'll need to wait to retrieve your bags.  Once you've got them, you can do your final clearance through Customs, which usually just consists of you handing your customs card to the agent at the exit.  You have to have all your checked bags with you to do this;  them's the rules.  I haven't been through Toronto with checked bags recently enough to comment on how long this can take (though if you're delayed getting through the line, you can at least expect not to wait as long for your checked bag.) Luggage procedures at YYZ have changed.  See edit below.
At this point, you need to put your bags back into the system.  This is probably the easiest part;  follow the signs for "Connecting flights to Canada" and they'll lead you to a conveyor belt you can drop your checked bag on.  You won't have to talk to an agent or anything.
You'll then need to go through security again;  I believe that once you've exited Customs, you've exited the secured area, and that there's no way around this.  This can also take a while, depending on the time of day.

To get this all done in 1:07 is certainly possible, but you don't have much margin for error.  You might consider calling up whoever sold you the ticket and seeing if they'll switch your Chicago-Toronto flight earlier or your Toronto-Halifax flight later without any fee;  I had a good experience doing this with Air Canada earlier this year.  (In my case, one of my flight times was shifted by Air Canada, leaving me with an eight-hour layover, but they booked me on a later incoming flight free of charge.)
Edit, Jan '16: Having flown from Hartford to Winnipeg via Toronto (and back) in December 2015, I can now say that they have upgraded their baggage system, and that you no longer need to re-claim your checked bags when flying either into or out of Canada via YYZ.  This definitely saves you some time.  Of course, there's still the possibility, as with any tight connection, that you could make it onto the connecting plane but that your checked bags don't.


should I use double negative in a compound sentence?

Question:

The following two sentences are compound having  negative expression-

They don't learn English at all and reach the target stage.
They can not write English sentence correctly and speak out their feelings in that language.

I found them from one of my text books,but it's seeming really horrible  to me as there is no use of negative word in the second clause of both of the sentences but still they want to express a pure negative state.
Now say me,will I adopt this structure or use negative word in the second clause?I think,I should opt for the second one because at times I may need to express positive state in the second clause,then it will be difficult to distinguish the meaning from each other.
Comment: No, that's exactly wrong.  They do reach.
Comment: I doubt that that is the meaning the book intends! I believe that the sentence is ambiguous, and I wouldn't think that a textbook would use it as an example of good usage.
Comment: Asker, regarding your first example, I want to check your comprehension before answering, to locate the problem. Do you think the upshot of the statement is that "they" __do__ or __do not__ "reach the target stage"?
Comment: obviously they don't reach.
@Codeswitcher
Answer: You're quite right: as it stands, the second clause implies that as a result of failing to learn English they do reach the 'target stage'!
This is a very tricky use of negatives with ellipsis. What the writer intends is something like this:
<code>  They don't     learn English at all
 and
 (they don't)    reach the target stage.
</code>
But this doesn't work. The expression at all is what linguists call a 'Negative Polarity Item': it is only used in negative contexts. In this sentence it combines with the not in don't and so to speak "absorbs" its negative sense before you get to the second clause. Consequently, that not cannot take the second clause into its scope. The parse looks something like this
<code>   They    [do not at all] learn English
  and
  (they)                   reach the second stage
</code>
You have a number of options for correcting this. One is what you suggest: adding a negative expression to the second clause. This  Since the negative in the first clause is comprehensive, not at all, a good choice for the second clause would be the equally comprehensive never:

They don't learn English at all and never reach the target stage.

That would be parsed something like this:
<code>   They  [do not at all] learn English
  and
  (they) [    never    ] reach the target stage
</code>
Another option is that suggested by snailboat: employ the 'exclusive' coordinator or instead of and, and pair the NPI at all with a corresponding NPI in the second clause

They don't learn English at all or ever reach the target stage.

<code>   They don't [at all] learn English
           or
              [ ever ] reach the target stage
</code>
Finally, you could coordinate learn English with reach the target stage using or, and move the NPI at all to a point where it modifies the coordination:

They don't learn English or reach the target stage at all.

<code>            (learn English         )
 They don't ( or                   )   at all.
            (reach the target stage)
</code>
ADDDED:
Your second sentence, "They can not write English sentence correctly and speak out their feelings in that language", is marginally acceptable; there's no ambiguity about the scope of the negator. But it would be better expressed with or, which alerts the reader to the fact that what follows falls under the scope of they cannot:

They cannot write an English sentence correctly or speak out their feelings in that language.
Comment: Thanx a lot.But I was thinking another option -
"They don't learn English at all and
fail to reach the target stage."
Isn't it better?
Comment: @rafiurrashid That's another possibility; in that case I would put a comma after *all*, which helps the reader understand that the following clause is maximally independent, sharing only its subject with the first clause.
Comment: Right & thanx again.
But another thing needs to be clarified.You have said that using the conjunction 'and' expresses totally incorrect or sometime marginally correct sesnse in that two sentences,but using 'or' expresses a well-transparent meaning...I wanna know why using 'or' doesn't need any negative word for the second clause? @StoneyB
Comment: @rafiurrashid It's complicated - *CGEL* spends about 20 pages on the contrasting uses of *and* and *or* - but in this sort of context, *not (A or B)* has the 'default' meaning "neither A nor B". (However, that's an implicature, not an entailment: it can be 'cancelled' by further specification.)


Does the TurboGrafX16 store switches and/or flags in RAM?

Question: Based the the specs I found for the TG16, it has 8 KB of RAM. I also found notes in the documentation of many opcodes that there is data stored in several "flags and switches" are these stored in RAM or in a designated register?
Answer: You are probably referring to the status register. This is a hardware register in the CPU, and is not stored in RAM.
Generally speaking, the HuC6280 is similar to a 6502-family CPU. You may want to acquaint yourself better with those parts; familiarity with them will make the HuC6280 easier to understand.
Comment: The 6502 was an extremely popular processor in its time. There were many books written about working with it. Read one.
Comment: @JackKasbrack It's a serious recommendation. Stack Exchange Q&A isn't a good medium to explain something this broad. A book is.
Comment: I am looking the acquaint myself with those parts. where/how do i do that?


Does the 'Channel' on Nocturne's fear continue if he is whimsy'd by LuLu?

Question: Just wondering if when Nocturne casts fear, and you whimsy him as LuLu will it stop the cast or will it continue? (provided he stays in range)
Answer: Yes, as long as you are still in range, Nocturne will indeed still fear you regardless on the fact that he is a harmless squirrel. But if you time Whimsey correctly (it takes 2 seconds for the fear to come into effect), you can cast Whimsey right as you become feared so he can't attack you while you are feared.
Using Whimsey to polymorph the enemy into something harmless is a new functionality that no other champions have. Because of this, there is some gray areas of how it will affect certain skills. Nocturne's fear is not a channeled skill, as you can tell because he is able to move. Champions are not able to move while they are channeling. It can disrupt real channeled skills like Katarina's Death Lotus and Fiddlestick's Drain.
There are some situations in which if Whimsey is cast at the last possible moment on champions with teleporting type skills (like Pantheon's Grand Skyfall), it would not disrupt it but instead teleport the enemy champion in the polymorphed form. This can be quite humorous when suddenly a cupcake drops from the sky to waddle around you.
Comment: I believe that the effects of whimsy will be exactly the same as a silence, but I haven't been able to test this extensively yet.
Comment: @RovingBlade, I cant remember off the top of my head right now but I've run across situations in which a normal silence would have stopped a skill but Whimsey didn't.
Answer: No, as it is not channeled. Once the fear is on you just just need to maximize your distance from nocturne or slow him/etc.
Answer: Nocturne's skill is a tether, not a channel. This means it will not be cancelled.
Proof:

 (Stonewall's Nocturne Team Battle, 5:25)


Is it possible to use Google Feedback in Google Search?

Question: Is it possible to use Google Feedback on Google Search? I want to suggest some improvements to make to Google Search's user interface. I've figured out how to use Google Feedback on Google+ and Youtube, but I still haven't found it for Google Search.
Answer: The link to the Google Feedback tool is always available at the bottom of the page of a search result.
Click on the "Give us feedback" link to add a comment and capture a portion of the webpage that you are referring to.
Answer: I don't think there is anything there natively on each search page. There is a quality form, not sure whether it still works.
Comment: See the latest answer to this question - there's a "give us feedback" link at the bottom of every search results page.


What are the regulations about ISS access for research?

Question: Are there any laws regulating access to the International Space Station for an Indian company, for research such as microgravity tests?
Comment: Can you be more specific please, as to what the Indian company wants? Do they want the astronauts to conduct experiments for them, or do they want access to data from previous experiments, or something else entirely?
Comment: I doubt that there are *laws* which govern this, but rather *regulations* and *international agreements*. Both can be flexible... for the right price. There already were private space tourists on the ISS, so yes, access to the ISS *is* for sale.
Comment: ISRO has been involved with the process to join the ISS project nations since 2009, and has been formally invited to do so in 2011. Unless there's a veto from any of the already participating nations (like e.g. US objection to China's involvement), there isn't any _law_ strictly prohibiting India to join. There are however many regulations that apply to all, and India isn't exempt from. Those depend on how India would like to partner with existing members and contribute to the project. That said, I think you need to [edit] your question to be a bit more specific and explain what you mean.
Answer: Astronaut time, payload transfer capacity, instrument time and other resources on the ISS are divided among the partaking nations depending on their financial commitment to the project. Also, some of the partaking nations have modules which they can use exclusively.
However, all the partaking nations are allowed to sub-sell their time and resources.
When the ISRO or a private Indian company would like to place an experiment on the ISS, they could contract any of the ISS partners to perform the experiment for them using the resources allotted to the partner. The price is a matter of negotiation, but it will certainly not be cheap.
Comment: But the IGA requires approval from all partners for a non-partner to come, so there might be political issues.
Comment: Thank you so much Mr. Philipp. Thanks for your valuable information


Trick Or Treat - What gives with the soundtrack?

Question: Anyone know why Trick Or Treat (1986) (which stars Gene Simmons and Ozzy Osbourne) didn't have a single track by either artist on the soundtrack?  And why they chose Fastway (of all bands) to do the majority of it?  I'm fairly confident that had a lot to do with its financial failure, but I'm just curious if anyone knows what De Laurentiis was thinking by doing that?  I don't ever recall them being overly popular or "up-and-coming".
Answer: Fastway, the band, recorded their debut album, also named Fastway, in the year 1983. According to wikipedia's sources, the debut album was a critical and commercial success.

After critical and commercial success, the band toured to promote the
  album (with one-time Fixx bassist Alfie Agius as their session bass
  player). The band then recruited Charlie McCracken, formerly of Taste,
  as "permanent" bassist, and released another success in the form of
  All Fired Up the following year. After the hardships of touring,
  Shirley and McCracken subsequently left.After critical and commercial
  success, the band toured to promote the album

So they could have been seen as an 'up and coming' band during 1986.
That could've been the reason why they were approached for the movie.
Secondly, in the same article on Wikipedia, they mention that

Fastway was approached to make the soundtrack for the heavy metal
  horror film, Trick or Treat. The film flopped, but the soundtrack
  re-established Fastway as a hard-hitting metal band. The soundtrack
  was a moderate success, and stayed on the Billboard Top 200 chart for
  eleven months.

So may be Fastway was not solely responsible for the movie's commercial failure.


Heater problem in my 25 gallon tank

Question: I have a 25 gallon tank last week I had bought a new heater with thermostat. It is 150 watts but the water seems not to be heating up. My Blue Line Shark has Ich so I raised the temperature to 32 degrees Celsius immediately. Can that also cause this problem after putting it in the tank?
Comment: [Some information about ich](https://pets.stackexchange.com/questions/1922/what-exactly-is-ich)
Answer: 150 watts in 25 gallons is plenty in normal heated room. Is the heater on? Is it set correctly? There is usually some light indicating that the heater is actually heating (if not, test it carefully with your finger - is it hot?). If it is going on and off and the temperature in the tank does not rise, it may be caused by insufficient water movement around the heater - point the filter outlet to the heater to increase the flow around the heater.
On a side note, 25 gallons is way too small for sharks. If the tank is used only for the treatment, OK; if it is their normal home, it is a problem. It may stress the fish and cause this, and many other health problems in the long run.
Answer: what is the ambient temperature in the room? try setting the heater a few degrees higher and see if that helps. In case the ambient temperature is low, the heater might not be able to help much. A higher wattage heater may help. Also bear in mind that a heater will cause loads of tank water to evaporate, which may need frequent replenishment.
Answer: I'm too lazy to look up the Celsius Fahrenheit difference but if your fish have ich I'd recommend bringing your tank temp up to 82F degrees and get API Super Ich Cure along with some aquarium salt. I've saved a lot of fish using that combo since I used to work at a fish store.
You can read up on how aquarium heaters work against room temp here Aquarium Heater Size Guide
Good luck!
Answer: Anything higher than 50 watts is overkill in a 25. I have found most thermostats to be unreliable ; Get an Eheim on the internet.

Heater problem in my 25 gallon tank


How come sonic booms only occur once at the speed of sound and not multiple times?

Question: Fighter aircraft today are capable of flying several times the speed of sound. Why is it that the sonic boom only occurs at the moment the plane crosses Mach 1?
Comment: Sonic booms are a continual process once your are at and above Mach 1.  You only experience it as a single boom as the shockwave passes you.
Comment: Are you suggesting that a sonic boom only happens as an aircraft crosses Mach 1, and then vanishes as it continues to accelerate? That is not the case.
Comment: @DavidRicherby Fair enough; In that case I would reformat this one clearly with that interpretation since that's a decent question. If we're wrong he could still open a new one later. Update: Changed the question correspondingly.
Comment: I will admit also I thought along the same lines when I was younger... I never quite got the idea until a few years later.
Comment: @DavidRicherby I was unsure if it was a question of (a) why it only occurs above Mach 1 (which IMHO the marked duplicate answers) (b) why it does not occur multiple times (i.e. multiple sonic booms for every Mach, indeed a new question) or (c) if it only occurs as a one-time event (which is wrong and would indeed be a new question). The question and text is somewhat ambiguous. Perhaps the author could elaborate a little and I would be happy to reopen it. As it stands I am unclear exactly what he would like to know...
Comment: @MikeFoxtrot Taking the title into account, I'd say the question is "Why does the sonic boom only occur once? By the way, the one time it occurs is the moment at which the aircraft passes Mach 1."
Comment: Sonic boom is well explained in [What is the simplest way to explain a sonic boom that is still technically correct?](http://aviation.stackexchange.com/questions/14783/what-is-the-simplest-way-to-explain-a-sonic-boom-that-is-still-technically-corre), including when it happens (particularly [this answer](http://aviation.stackexchange.com/a/14790/524)).
Answer: Your question is:

Why is it that the sonic boom only occurs at the moment the plane crosses Mach 1?

The answer is: It doesn't. Sonic boom first occurs when the plane crosses Mach 1 and the plane continues producing sonic boom as long as the speed stays above Mach 1.
Another part of your question is:

How come sonic booms only occur once?

And the answer is: because the plane flew over you once. If the plane were to turn around and fly over you a second time you'd hear two sonic booms.
When you hear a sonic boom it doesn't mean that that boom was generated at Mach 1. It only means that the boom was generated at speeds equal to or greater than Mach 1. For example, a plane travelling at Mach 3 would still produce a sonic boom but you'd still only hear it once because the "boom" would only reach your ear once.
To understand this you need to understand what a sonic boom is.
Various parts of the airplane generate sound. Form the roar of the jet engines to the whistle of the skin of the aircraft moving through the air.
When travelling at normal subsonic speed. These sounds travel normally through the air and what you hear is a continuous sound of an airplane flying.
When travelling at or faster than the speed of sound, all these sounds arrive at your ear simultaneously. That is to say, if normally you'd be able to hear a plane passing overhead over a period of 10 seconds (for example) then at supersonic speeds all those 10 seconds of sounds (engine roar, woosh of the wings etc.) arrive at your ear at the same moment.
Since all the sounds you'd ever hear from the airplane arrive at the same time, the result is a very loud boom (all the 10 seconds or more of sound added together).
That's why you only hear it once typically.
There are exceptions though. If the plane is long enough, and the nose and tail generate loud sounds, it is possible to experience a double sonic boom caused by the tail generating a second boom. But generally, even a very long plane like the 747 or A380 (or Concorde) would take only a very tiny fraction of a second to travel the length of their body at supersonic speeds. You'd probably need a plane a mile long to experience a proper double boom.
Comment: "*Since all the sounds you'd ever hear from the airplane arrive at the same time, the result is a very loud boom (all the 10 seconds or more of sound added together).*" When the aircraft moves in air, it disturbs it, pressure will re-equalize, but if the aircraft is supersonic, air cannot move faster than "the speed of sound", so a huge pressure differential forms, propagated away at sound speed. If it reaches our ears before equalization, we first perceive the diluted front pressure, then the abrupt change as the differential passes. It works the same with a totally silent aircraft.
Answer: There is always a disruption (i.e a perturbation) in the air by a object traveling through it. Each one can be seen as a sphere (or circle in a 2D diagram). At speeds below Mach 1, these disruptions never converge, i.e. the spheres never meet. However, at any speed beyond Mach 1, they no longer travel faster than the aircraft and get 'left behind'. In this case the sides of each expanding sphere converge along a cone shape into a powerful shock wave that we perceive with as a bang.

 Source
The only difference is that as the aircraft becomes faster, the angle of the sonic boom in regard to the direction vector of the aircraft decreases: The cone becomes more acute as the spacing between each imaginary sphere becomes greater. You can never generate more than than one sonic boom, since it's a one-time transition. (On a more complicated note, some vehicles, included the space shuttle, pull of two sonic booms by disrupting the air twice)
You would perceive the same thing with a boat- above a certain speed you would generate a wake going outwards in two directions to the side behind you.

"Fjordn surface wave boat" by Edmont - Own work. Licensed under CC BY-SA 3.0 via Wikimedia Commons


Access to exchanges' (especially Mt. Gox's) transaction history?

Question: I'm attempting to do statistical research on the Bitcoin market, and I would like to have access to the transaction data of as many exchanges as possible. Specifically, I'm looking for every trade made on a given exchange. Mt. Gox is obviously my primary interest because it handles the highest volume. Is this data available for download anywhere, or am I going to have to start collecting it myself? Specifically, I want to be able to store all transactions in a SQL database, so I would like them in an easily parsable format.
Answer: You can use the API to retrieve such data.
Comment: Ah, right, specifically [here](https://en.bitcoin.it/wiki/MtGox/API/HTTP/v1#Multi_currency_trades). Thanks @Lohoris.
Answer: I found a SQL database of all Mt. Gox transactions (updated every few hours) along with the accompanying Python scripts here.