Whenever I insert a pen drive, I am not able to open it.  Vista shows me this error:     Please insert disk into removable drive   I have tried changing the drive letter, but it didn't help.
I have a USB flash drive which is no longer recognized by my computer. Windows Disk Management and DiskPart report No Media with no storage space (0 bytes) on the drive and I cannot partition or format the drive:     If the drive appears in Windows Explorer, trying to access it returns an error message indicating that there is no disk inserted, such as the following:     Please insert a disk into drive X:.   Various disk partitioning and data recovery utilities don't recognize the drive or only give a generic name for the drive and cannot access the contents of the drive.  What can I do? How do I recover data from the drive?     This question comes up often and the answers are usually the same. This post is meant to provide a definitive, canonical answer for this problem. Feel free to edit the answer to add additional details.
This thing came up in a combinatorics course I am taking.  Choose a fixed set of primes $p_1,p_2,\dots,p_k$ and let $A_n$ be number of integers in $\{1,2,\dots,n\}$ which are not divisible by any of the $p_i$'s. $A_n$ is given by $ n - \sum_{1\leq i_1 \leq k} \lfloor \frac{n}{p_{i_1}} \rfloor + \sum_{1\leq i_1 &lt; i_2 &lt; k} \lfloor \frac{n}{p_{i_1}p_{i_2}}\rfloor - \dots $. Now, if $n$ is divisible by each of the $p_i$'s then we have the simpler expression : $A_n = n \prod_{i=1}^{k}(1-\frac{1}{p_i})$(added later : note I am not assuming $n = \prod_{i=1}^{k}p_i$ here, this holds true whenever $n = c \prod_{i=1}^{k} p_i $ for some integer c, since each $\lfloor \frac{n}{p_{i_1} \dots p_{i_j}} \rfloor = \frac{n}{p_{i_1} \dots p_{i_j}}\ )$.  Another student pointed out that even if $n$ does not have $\prod_{i=1}^{k} p_i$ as a factor, the approximation $B_n = n \prod_{i=1}^{k}(1-\frac{1}{p_i})$ to $A_n$ is quite close in some specific cases. It is easy to see that $\lim_{n\to\infty}\frac{A_n - B_n}{n}=0$ as $\lim_{n\to\infty}\frac{1}{n}\lfloor \frac{n}{p_{i_1}p_{i_2}\dots p_{i_j}} \rfloor \to \frac{1}{p_{i_1}p_{i_2} \dots p_{i_j}},$ however that is not strong enough to imply that $A_n - B_n$ will be always close. Is there any way to analyze how well this approximation will perform in general? I am interested in the worst case for small to moderately sized $n$.  Just to give a feel of how close $A_n$ and $B_n$ can get, assuming the set of primes is $\{2,3,7\}$ we have (assuming my program is correct):  n     A(n)     B(n) 17    5    4.86   27    8    7.71   37    11      10.57   107   31      30.57   1111  318     317.43   3001  858     857.43   4007  1145    1144.86   5000  1429    1428.57 . The equivalence of open-set definition of continuous mappings to the $\epsilon-\delta$ definition A function $f: M\rightarrow N$ is defined to be continuous iff $\forall$ open set $U\subseteq N$, the preimage of $U$ is also open.  I was trying to prove that such a definition would be equivalent to the $\epsilon -\delta$ definition in a metric space, and I could only do so if I assume $f$ is surjective, or otherwise a counterexample would be $g: \mathbb{R}\rightarrow\mathbb{R}$ where $g(x)=x^2$. As if I take $U=(-1,1)$, then its preimage is $[0,1)$, which is neither open or closed. In fact, any $U$ containing elements that cannot be achieved by $g$ would face the same problem.  So I was wondering that have I remembered the definition of preimage wrong, or do I need to make sure that $U$ must be chosen from the image set of $f$? How may I reference the script tag that loaded the currently-executing script? How can I reference the script element that loaded the javascript that is currently running?  Here's the situation. I have a "master" script being loaded high in the page, first thing under the HEAD tag.  &lt;!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"  "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"&gt; &lt;html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en"&gt; &lt;head&gt; &lt;script type="text/javascript" src="scripts.js"&gt;&lt;/script&gt;   There is a script in "scripts.js" which needs to be able to do on-demand loading of other scripts. The normal method doesn't quite work for me because I need to add new scripts without referencing the HEAD tag, because the HEAD element hasn't finished rendering:  document.getElementsByTagName('head')[0].appendChild(v);   What I want to do is reference the script element that loaded the current script so that I can then append my new dynamically loaded script tags into the DOM after it.  &lt;script type="text/javascript" src="scripts.js"&gt;&lt;/script&gt; loaded by scripts.js--&gt;&lt;script type="text/javascript" src="new_script1.js"&gt;&lt;/script&gt; loaded by scripts.js --&gt;&lt;script type="text/javascript" src="new_script2.js"&gt;&lt;/script&gt; Eigenvectors of real symmetric matrices are orthogonal Error reading from file: Input/output error Installing Ubuntu with Fake RAID 1 I'm trying to find the roots of $x^4+1$. I've already found in this site solutions for polynomials like this $x^n+a$, where $a$ is a negative term. I don't remember how to solve an equation when $a$ is a positive term as the equation above.  Thanks I was going to make a filter for the &quot;&quot; by excluding some sites from it.  I noticed  which talks about &quot;negative filtering&quot; but does not explain how one can do it or if it is possible.  There does not seem to be a way to do this, though.  On the filter page, my only options are:  So how can I do &quot;All sites except [list]&quot;? It would also be nice if this could include similar functionality with the meta checkbox.  Something like &quot;All main &amp; meta sites except...&quot; Objects not showing in final render When I switch to render mode, they show up, and they show when pressing F12, but when clicking the 'Animation' button, nothing shows. If anyone knows how to help, please do.  Edit: I have enabled rendering using the cameras, still nothing.  Edit #2: What the, some how transferring all of the objects from layer 1-2 does the trick. I guess my camera was set up for the second layer even though it was physically in the 1st. Anyone like to explain?  For anyone who's really curious, :  Also, it may seem like having the animation length of 1 frame seem bad, but I've done that for other files and they work fine. Example of a domain where all irreducibles are primes and that is not a GCD domain One has the following relations for a domain $R$:  $R$ GCD domain $\Rightarrow$ All irreducible elements are prime  $R$ PID $\Rightarrow$ $(R$ GCD domain $\land$ $R$ statisfies ACCP$)$  $R$ UFD $\Leftrightarrow$ $(R$ GCD domain $\land$ $R$ satisfies ACCP$)$  $R$ satisfies ACCP $\Rightarrow$ $(R$ UFD $\Leftrightarrow$ All irreducible elements are prime$)$  $R$ GCD domain $\Rightarrow$ $(R$ UFD $\Leftrightarrow$ $R$ atomic domain$)$  So what is the difference between a GCD domain and a domain where all irreducible elements are prime? What is the "weakest" predicate $P$ such that  $R$ GCD domain $\Leftrightarrow$ $($All irreducible elements are prime $\land$ $P(R))$ ? What should I do when I have lenses with different filter thread sizes? How to take a site offline using Drush? Submitting a URL to Google using PHP/cUrl I try to clean my mid-2015 Macbook Pro with Retina display by wiping the screen with a damp cloth and then immediately drying.  However, there seems to be left some residue/streak marks, which look very oily. Sometimes these disappear after a few minutes, but they are still very unsightly, and a bit worrying (is there something wrong with my screen?)  I'm wondering if there are other cleaning techniques which avoid this issue, or whether this is completely normal behaviour.  Thank you! Shortcut for toggling between different windows of same app? Why is jumping into water from high altitude fatal? If I jump from an airplane straight positioned upright into the ocean, why is it the same as jumping straight on the ground?  Water is a liquid as opposed to the ground, so I would expect that by plunging straight in the water, I would enter it aerodynamically and then be slowed in the water. Can I tap a creature with summoning sickness to pay "tap an untapped creature you control" costs? Our 3 months old baby is very keen on rolling over and being on his stomach. Most of the time he automatically rolls over in a few minutes after we put him on his back, including during bed time. Is this dangerous? We are particularly worried that   his nose maybe blocked when facing down it is said that SIDS risk increases when a baby sleeps on his stomach   If it is dangerous, how can we stop this, especially during bed time or other times when we can't watch him continuously? Strip whitespace from jsp output How can I strip out extra whitespace from jsp pages' output?  Is there a switch I can flip on my web.xml?  Is there a Tomcat specific setting? I was laying on my bed, reading a book when the sun shone through the windows on my left. I happened to look at the wall on my right and noticed this very strange effect. The shadow of my elbow, when near the pages of the book, joined up with the shadow of the book even though I wasn't physically touching it.   I have posted :The video seems to be the wrong way up, but you still get the idea of what is happening.  What is causing this? Some sort of optical illusion where the light gets bent?  Coincidentally, I have been wondering about a similar effect recently where if you focus your eye on a nearby object, say, your finger, objects behind it in the distance seem to get curved/distorted around the edge of your finger. It seems awfully related...  EDIT: I could see the bulge with my bare eyes to the same extent as in the video! The room was well light and the wall was indeed quite bright.