Using Google CDN to load scripts gives poor user experience in China
Stack Exchange's heavy reliance on external scripts
I have a population of phone calls - 200,000.  There are different reasons for each call, but lets assume the number of reasons is known. i.e. 7 different call reasons: 1) Check on order 2) Cancel order 3) Billing information 4) Account information etc...  My question is, I want to get a statistically significant sample size so the number of calls I listen to in my sample are representative of the distribution of the reasons in the overall population of 200,000 calls.  What should the sample size be? Which methods to use to calculate the sample size? Evaluate definite interval of normal distribution I know that an easy to handle formula for the CDF of a normal distribution is somewhat missing, due to the complicated error function in it.  However, I wonder if there is a a nice formula for $N(c_{-} \leq x &lt; c_{+}| \mu, \sigma^2)$. Or what the "state of the art" approximation for this problem might be. Should log file streams be opened/closed on each write or kept open during a desktop application's lifetime? I have downloaded and installed the newest  for my Windows 7 (64-bit OS), but when I want to install 64-bit Linux, the New->Create Virtual Machine only displays 32-bit option, no 64-bit option. Could anyone give any clues about this issue? Thanks very much in advance! Algorithm to see if two voxels are interconnected Re-enabling backspace as "go back" in recent Chrome Since start of this summer, I think that Google removed the option of using backspace for returning to previous page or so.   I was wondering, if there exist any chance, of undo-ing this thing? Is there such thing that would help me, such as downgrading Chrome or using any additional add-ons or something such as this for getting this glorious function back?  It's nearly impossible for me to forget this shortcut (as old habits die hard, lol) and keep pressing it and later on using the mouse to go back. How to chat to all I very rarely see chats too all and don't know how to do it myself. Normally it's SHIFT + ENTER The following hotkeys have been tried: - SHIFT + ENTER - CTRL + ENTER - ALT + ENTER How to do research in two very different fields? What are the TeX definitions for the hyphen and dashes -, --, and ---? I've tried latexdef which does not handle --- as the operand. And \texemdash is defined as a character. So that leaves me once again leaning on the collective wisdom of the group :) I often see questions edited into this form:     Lorem ipsum dolor sit amet blah blah blah paragraph paragraph original question.            UPDATE: The Lorem disappeared and left this message: "new information".   I find this format unaesthetic (since Stack Exchange posts are supposed to be useful in the long term and update boundaries are artifacts of the creation rather than the content) and feel that new information should, whenever possible, be incorporated into the original text “as if it had always been that way” if practical, and pointing out an update should be done mostly in comments.  Is this an appropriate writing style, and if so under what circumstances? If not, should it be removed or discouraged? Action to crop a photo with user input. The batch processing I'm stumped.  All I need to do is open my photo, have the action stop to wait for me to decide where the crop should be (to center the important part of the photo), then close that photo so the batch processing can go get the next photo.  I see the "inset stop" is the key, but it never allows me to crop, it just moves on to the next photo. Create WiFi hotspot on ubuntu Although many questions have already been asked regarding WiFi hotspot, I didn't get any of the solutions working for me.  I connect to the Internet using a 3G Dongle of Huawei 3772 (Vodafone). The connection type is Mobile Broadband connection. I have to share this Internet connection with my other devices like mobile phones and laptops.  How can I create a WiFi hotspot connection for this connection.  I am using Ubuntu 12.04 LTS.  I would like to note that I have already tried some help links from Ubuntu but, they are so confusing that I could not understand them. Classic ASP SQL Injection Protection What is a strong way to protect against sql injection for a classic asp app?  FYI I am using it with an access DB.  (I didnt write the app) Trying to make aliases that open the last modified file One thing that I frequently do is edit the most recently modified files, so instead of typing "ls -lr" and then "vim lastfile", I thought I would make some shortcuts in my ~/.bash_profile file:  alias via="vim `ls -rt | tail -1`" alias vib="vim `ls -rt | tail -2 | head -1`" alias vic="vim `ls -rt | tail -3 | head -1`" alias vid="vim `ls -rt | tail -4 | head -1`" alias vie="vim `ls -rt | tail -5 | head -1`"   The problem is that, weirdly enough, these commands don't work.  They open some file that isn't one of the last, or even a file was deleted from the current directory (I wonder if there's some kind of file cache updating issue in the directory.  This occurs on both my local machine and the cluster I work on).  However, if I type vim `ls -rt | tail -1` directly, without using the alias, it works every time. I'hv seen every 2 pin SMPS AC to DC adapters shows a little high voltage respective to the ground on the out put, on both + and GND wires(or more if more wires present).  This voltage is high enough to light small neon bulbs or a line tester, but very low current, barely could be felt. This voltage vanishes if I connect the output to ground somehow, e.g. touch it while standing on floor bare foot.  As the size of the adapter increases, the AC voltage and current increases. When laptop adapters are powered from a ungrounded AC outlet, they gives reasonable shock from the 19V DC(or whatever else) output.  Perhaps this is the reason why many 3 pronged laptop adapter carries a warning CONNECT ONLY TO GROUNDED OUTLET Connecting to a grounded outlet magically vanishes the high voltage.  I am aware about the EMI filtering capacitor connected between high voltage and low voltage ground, I tried to solve this by removing them, but this trick is not working.   Why and how this mysterious AC voltage is created ?  Is it harmful to sensitive electronics components ? Is there any way to solve this without grounding the DC output side ? I am very confused. Unless I am mistaken, I know "it" has to be a noun of some sort, but I am unable to figure out what noun "it" is referring to.   What is "it" in the following sentence:      It is clear that Bob likes doughnuts.   Heres another couple of examples:     It is impossible to fly. A well-known application of the MVT is to prove that any $f: \mathbb{R} \to \mathbb{R}$ with $f'= 0$ is constant. But of course, the MVT relies fundamentally on the properties of $\mathbb{R}$, and in particular does not hold in $\mathbb{Q}$. A standard counter-example is the function $f :\mathbb{Q} \to \mathbb{Q}$ defined by $ f(x)=0 $ if $ x &lt;\sqrt{2}$, and $f(x)=1$ if $ x &gt; \sqrt{2}$, for this function is locally constant. There are several ways of thinking about the difference between $\mathbb{R}$ and $\mathbb{Q}$ : $\mathbb{R}$ is connected while $\mathbb{Q}$ is totally disconnected, closed bounded intervals are compact in $\mathbb{R}$, but not in $\mathbb{Q}$, $\mathbb{R}$ satisfies the least upper bound axiom, $\mathbb{Q}$ does not.   Now, I wanted to see how far one could push this counterexample - is there a function $f :\mathbb{Q} \to \mathbb{Q}$ such that $f'=0$ and $f$ is strictly increasing? Clearly, any slight modification of the usual counterexample where $f$ is locally constant will not do. Also, one can show that if $f$ is uniformly differentiable with derivative zero, it must be constant, even in $\mathbb{Q}$, so I knew I was looking for non-uniformly differentiable but still differentiable $f$.   Eventually, I came up with a construction, albeit not a very explicit one: the idea is that, since $\mathbb{Q}$ is countable, one can enumerate it $q_{1}, q_{2}, q_{3}, \cdots$, and then define $f: \mathbb{Q} \to \mathbb{Q}$ inductively and recursively. If one could define $f$ in such a way that $ \forall \ q_{n} \in \mathbb{Q} \ \exists \ c_{n} \in \mathbb{Q} : \forall \ x \in \mathbb{Q} \ |f(x)-f(q_{n})| \leq c_{n}|x-q_{n}|^2$, and $f$ is strictly increasing, we would be done. The recursive definition essentially defines $f(q_{n+1})$, after having defined $f(q_{1}),f(q_{2}),f(q_{3}), \cdots , f(q_{n})$, in such a way that these inequalities hold and $f$ is strictly increasing, and at each step the new $c_{n}$ is chosen large enough so that these inequalities do not become incompatible at subsequent steps ( I am willing to provide more details of this construction if asked).  Note that, as $n \to \infty$, we must have $c_{n} \to \infty$, so that $f$ is not uniformly differentiable. Interestingly, the only key fact about $\mathbb{Q}$ used in the construction is that it is countable, so in a sense the construction provides a proof that $\mathbb{R}$ is uncountable, given the MVT.  While the construction works, it is not very simple nor explicit, which is perhaps to be expected, and the function must be evaluated point by point in the order given by the enumeration of $\mathbb{Q}$. So I was wondering if anyone else knows or can come up with a simpler construction of a function $ f : \mathbb{Q} \to \mathbb{Q}$ such that $f'=0$ and $f$ is strictly increasing. Any thoughts and ideas are welcome.  Edit: I've asked the same question on MO: How to correct for small p-value due to very large sample size Error installing Apache2 Server Unable to 'apt-get dist-upgrade' due to appstreamcli database error I have created a USB stick with a persistent Ubuntu 16.04 (release version). I tried a couple of ways, using Startup Disk Creator and MultiSystem, but I get the same end result.  When I boot into the USB and do 'apt-get update', all is well.  When I try 'apt-get dist-upgrade' I get:     ** (appstreamcli:2761): CRITICAL **: Error while moving old database out of the way. AppStream cache update failed.   The only reference to this error message I can find is  but would appear to be fixed, at least fixed by the time the release version of Ubuntu 16.04.  Aside: I want to test Unity8, which includes installing software.  I don't have a spare computer, so I thought a persistent USB would do the trick.  Any takers?