What does it mean that a function is uniformly continuous? (Geometrically)
Intuition for uniform continuity of a function on $\mathbb{R}$
Fundamental question about dimensional analysis Why isn't the product rule used in the definition of mechanical work? Recursive cast from SimpleXMLObject to Array How do World of Warcraft referrals and the free month work? I sent the referral link to my boss and he bought the game and applied his CD key.  He now has a paid account linked to mine:    Yet when I view my World of Warcraft account, it seems they didn't give me the free month. It appears I only have the free month that came with my Battlechest purchase.  I just created and bought my account this morning. Would this affect the free referral month in any way?    We haven't seen each other or partied online in the game yet, do we need to do that first in order for me to receive the month? How do I start a process from C#? All rounds of AES (and Rijndael) have a MixColumns step, save the last round which omits it.  DES has a similar feature where the last round differs slightly.  The rationale, if I recall correctly, was to "make the cipher appear similar in reverse as it does in the forward direction."  Why does this make AES$^{-1}$ look similar to AES?  And how does this help in implementing the block cipher? How do you access the matched groups in a JavaScript regular expression? I want to match a portion of a string using a  and then access that parenthesized substring:  var myString = "something format_abc"; // I want "abc"  var arr = /(?:^|\s)format_(.*?)(?:\s|$)/.exec(myString);  console.log(arr);     // Prints: [" format_abc", "abc"] .. so far so good. console.log(arr[1]);  // Prints: undefined  (???) console.log(arr[0]);  // Prints: format_undefined (!!!)   What am I doing wrong?    I've discovered that there was nothing wrong with the regular expression code above: the actual string which I was testing against was this:  "date format_%A"   Reporting that "%A" is undefined seems a very strange behaviour, but it is not directly related to this question, so I've opened a new one, .    The issue was that console.log takes its parameters like a printf statement, and since the string I was logging ("%A") had a special value, it was trying to find the value of the next parameter. I was editing my mesh and I wanted to only see a part of my mesh, so I pressed alt+B to only show a selected area. However, I did ctrl+B and created a red rectangle on my screen (I don't know what it does). Does anybody know how to get it off? A commercial airport being any airport that has regular scheduled passenger flights.  The mathematics of  got me thinking: is the network of scheduled flights a connected graph?  That is, is there a pair (or triplet or even larger set) of airports such that they only have scheduled flights with each other?  Or can you get from any airport to any other?  Ignore vagaries like cargo and general aviation. I'm looking for two airports that I can shuttle between, but would have to drive (or sail) to get to one or the other of them. Is there a shorter alternative for "Enjoy your meal"? The French have "Bon appetit".   In Belgium and the Netherlands we have "Smakelijk".  Is there a short way to wish someone a good meal in English? What is the difference between ref and out parameters in .NET? What are the situations where one can be more useful than the other? What would be a code snippet where one can be used and another can't? Is it possible to scale specific apps on Windows 10? How do I install Ubuntu from an USB drive / create a live USB-stick in Windows? I tried to use the usb-creator.exe from Ubuntu 10.10 desktop i386 ISO image and it does create an USB stick that doesn't boot. When I try to boot from it I get:     Operating System not found.   I try to do this from Windows 7 x64. I'm not looking to create a live Ubuntu media, only an installation USB disk.  I repeated the process several times and I even tried to reformat the USB drive (FAT32), no success yet.  The USB stick is a 8GB one. Powershell Rename Multiple Files with LastWriteTime Prefix I am trying to put together a Powershell script that will:  -Search recursively from a root directory -Exclude files with existing "yyyyMMdd " file name prefix -Rename the files not excluded above with ""yyyyMMdd " file name prefix based on their specific LastWriteTime  Note: ideally, this script should include all file type extensions  I have tried myself, but it would seem to be above my head, as my attempts are not going well.  Thanks, in advance.    #StampMe.ps1 param( [string] $fileName)  # Check the file exists if (-not(Test-Path $fileName)) {break}  # Display the original name "Original filename: $fileName"  $fileObj = get-item $fileName  # Get the date $DateStamp = get-date -uformat "%Y-%m-%d@%H-%M-%S"  $extOnly = $fileObj.extension  if ($extOnly.length -eq 0) {    $nameOnly = $fileObj.Name    rename-item "$fileObj" "$nameOnly-$DateStamp"    } else {    $nameOnly = $fileObj.Name.Replace( $fileObj.Extension,'')    rename-item "$fileName" "$nameOnly-$DateStamp$extOnly"    }  # Display the new name "New filename: $nameOnly-$DateStamp$extOnly"   I am hoping to change the line:  $DateStamp = get-date -uformat "%Y-%m-%d@%H-%M-%S"   To be LastWriteTime instead of get-date, but I have no idea how to make this happen.  This code (from another Super User question):  Get-ChildItem "Test.pdf" | Rename-Item -newname {$_.LastWriteTime.toString("yyyyMMdd") + " Test.pdf"}   ...successfully renames a single file, but I can't seem to integrate this into the larger script.    With regards to running the above recursively, I have tried this (also from ):  foreach ($file in get-ChildItem *.* -recurse) { ./StampMe.ps1 $file.name }   Which succeeds to apply the PS script to files in the root directory, but fails to apply to any files in the sub-folder tree that propagates from the root directory. Where is the pet store? I was playing sims freeplay on my iPod yesterday but could not find the pet store. Where is the pet store in the preteens are here update? Issue with 'StringVar' in Python Program Get specific GPS location somehow on windows 8 In every keyboard that I have used, the keys are arranged so that the keys are staggered a small increment to the left from the previous row. Q is above and slightly to the left of A, and A is above and slightly to the left of Z. This pattern continues across the entire board. Case in point:    What is the motivation behind this design? I would think that a column layout would be easier to type on - and indeed, many ergonomic keyboards seem to go with a column layout, where Q is directly above A and so on. What factors influence the spring constant? For certain springs we have been taught that Hookes law, $F=-kx$ works. For such springs, what factors determine k. For instance, k is proportional to length. Can k be expressed in terms of dimensions, mass and other fundemental quantities, or is k a fundemental property of the spring itself? Is it unethical to cite a paper or book that you have never looked at? Suppose I see that Book X is cited by several papers with reference to some particular Fact Y. I wish to cite Fact Y. As far as I know, Book X is the only reference for Fact Y.   I have never looked at Book X. Nonetheless, I cite it like this:  'Fact Y' (see Book X)  My question is: Is this ethical, given that I've never looked at Book X?  More context for my question. I am NOT asking whether this is good scientific practice. I am NOT asking how a good scientist should actually go about citing Fact Y. I am NOT asking if this could undermine your credibility as a scientist.  Instead, I am asking this question because it seems to be a somewhat-common practice. And moreover, as far as I know, no scientist has ever been issued even an official rebuke (much less fired) for engaging in such practice. This would suggest to me that this practice is not considered to be unethical.   Of course, it is not binary as to whether a practice is unethical. But I would simply like to know whether the academic community in general considers this to be even a mildly unethical practice. Or if it is perhaps very slightly unethical, but not a big deal. Or if it is not in the least bit unethical.