How to check significant change in the actual population, not sample
Statistical inference when the sample "is" the population
Get the client IP address using PHP Are there some good overviews of basic facts about images and inverse images of sets under functions? Getting an error in W3C Markup Validation when trying to get a whole  element as a link in a page How can time dilation be symmetric? Suppose we have two twins travelling away from each other, each twin moving at some speed $v$:    Twin $A$ observes twin $B$’s time to be dilated so his clock runs faster than twin $B$’s clock. But twin $B$ observes twin $A$’s time to be dilated so his clock runs faster than twin $A$’s clock. Each twin thinks their clock is running faster. How can this be? Isn’t this a paradox? Mysql: Select all data between two dates If $g \circ f$ is surjective, show that $f$ does not have to be surjective? SharePoint Migration 2007 to 2013 We're planning to upgrade an existing farm from 2007 to 2013. I learned that the best way and maybe the only way to achieve this is by migrating in two steps. 2007 to 2010 and 2010 to 2013. The actual farm is a sql-server(2008r2 64 bit) and a sperate sharepoint-server(web-frontend, etc....) I want to keep the sql-server as it is, if possible and we want to install a new 64bit host for sharepoint 2013. We will design a new branding for 2013 afterwards, so we need to keep the content, but not the layout. There's so much about migration available on the web, but Can I find something like best practises? What's wrong with "I'll open you the door"? When I call the buzzer outside my girlfriend's flat, she sometimes says *"I'll open you the door". I correct this to "I'll open the door for you".  I've never heard a native speaker say it the first way, which is why I think it's wrong. But I can't explain why.  There is a pattern in lots of English phrases that would suggest both are correct. A few common examples:   Give the keys to me before you go — Give me the keys before you go I'll buy a coffee for you at the cafe — I'll buy you a coffee at the cafe We sent a text to Martin on his birthday — We sent Martin a text on his birthday   The left-hand side is more formal, and the right-hand side is more common in everyday speech.  What do you call this pattern?  What makes the 'open-the-door' sentence an exception? I am using Ubuntu 16.04, with Gnome 3.18. Using extensions I have gotten rid of the dash panel and only use the Applications Menu in the upper left-hand corner of the screen. (I don't have Unity.) What I can't figure out is how do you add a new program, move software around to different categories, and create new categories?  Also, any keyboard shortcut to access the Applications Menu? Lately my laptop (HP g42 247sb) screen is damaged, so I hook it up with an external monitor (LG something) and it works fine now.  The only annoying thing is I cannot navigate the BIOS menu for some tweaking because the BIOS not shown on the external monitor, instead, it only shown on the broken laptop screen, and  it only output to my external monitor when Windows/OS is logged-on.  So, is there anyway I can force output during BIOS/BOOT/POST to my external monitor?  Things I have done and didn't work:   Set my LG monitor as primary display on both window properties and Intel Graphics panel  Enter the BIOS (F10 key) and press the Fn+F4 key (change display output). Disable and uninstall my internal screen (broken laptop screen) using device manager and restart, but Windows (BIOS?) install it back on log-on. Closed lid/Magnet on sensor. How do I remove this wall plate with no visible screws? I'm amazed how complicated this wall plate is to remove. It is made of plastic and accommodates a phone jack and a coaxial cable. Please see the images that accompany this question. I've searched it thoroughly and there are no tabs anywhere on the face or edges to press in. There are no screws. I've pulled on it pretty hard, hoping that it would pop off, but if I pulled any harder it surely would break. Of course, I had the coaxial off while I tried to remove the plate. The brand name on the phone jack part is &quot;KRONE&quot;. Has anyone seen a wall plate like this? If so, how do you remove it? I have to say, I'm absolutely blown away by how ridiculously difficult this is. Any help would be appreciated. I'm using an iPhone, but I would imagine it's the same for other mobile devices as well.  If you browse to any stack exchange site, you get a very well made mobile site.  The only gripe that I have is that I can't find any way to view the number of visitors to my questions?  Am I missing something or could this possibly be integrated into the mobile renderer? How can I prevent Google mistakenly offering to translate a page? Several of my site's pages are appearing in search results with [Translate this page] next to it. When I click that it takes me to Google Translate and translates my page "from Catalan to English".  The pages are in English but have a couple of foreign words (actually Japanese romanisations, not Catalan) that appear to be tripping Google up.  A few weeks ago I set the html tag to &lt;html lang="en"&gt; which from research appears to be the best method to specify the language of a document. Google has cached the pages with this attribute but it is still offering to translate.  More research led me to a "notranslate" attribute which prevents translation entirely: &lt;html lang="en" class="notranslate"&gt;. The problem now is users cannot translate from English to their desired language!  Are there any other solutions that force Google to parse my site as English only? When I upload an image to Stack Overflow, I cannot see my JPEG file in my post. It's all blank. I've tried it with different files, but gotten the same result. A bold plus symbol in math mode Review sections to be always in the same place How do I disable usb storage? I'm using Ubuntu 12.04 and I want to block usb storage on it. What is the correct way to do this? I have joined corresponding Local Enterprise Partnerships table data into a polygon shapefile containing UK Local Authorities.      How do I Dissolve or Merge the the Local Authorities polygons by LEP_NAME as shown in the screenshot?   Ideally, I would like to retain the Local Authority attributes with the resultant merged polygons. I have zero scripting knowledge so am looking for a tool based solution. Any help or pointers much appreciated.    Additional Note: When attempting to use the dissolve tool the LEP_NAME field is not available as shown above. The LEP attribute data was created in Excel, saved as CSV format and joined to the Local Authority polygon shapefile. There are duplicate IDENTIFI0 fields as shown in the other screenshot - could this be the root of the issue? percent signs in luacode* environment (LuaLaTeX) Can someone explain what happens here:  \documentclass{article} \usepackage{luacode} \begin{document}  \begin{luacode*} tex.print("xx\%a","yy\\%b","zz\\\%c") \end{luacode*}  \end{document}   The result is xxyy%b zz%c. (The xx,yy,zz is clear.) The \%a is "ignored", the \\%b and the \\\%c results in the "same" %b (or c). What is the preferred way to get a % in the PDF output? Why is the \%a ignored? What does TeX see after returning from the lua call? Who uses Dual_EC_DRBG? Recent news articles have suggested that the NSA may be involved in trying to influence the cryptography in public standards or commercially deployed software, to enable the NSA to decrypt the encrypted traffic.  For example, .  The New York Times article specifically mentions a 2006 NIST standard, where two Microsoft engineers later discovered a serious problem in the scheme.  The New York Times article explains how the standard was written by the NSA, who pushed the scheme hard:     Simultaneously, the N.S.A. has been deliberately weakening the international encryption standards adopted by developers. One goal in the agency’s 2013 budget request was to “influence policies, standards and specifications for commercial public key technologies,” the most common encryption method.      Cryptographers have long suspected that the agency planted vulnerabilities in a standard adopted in 2006 by the National Institute of Standards and Technology, the United States’ encryption standards body, and later by the International Organization for Standardization, which has 163 countries as members.      Classified N.S.A. memos appear to confirm that the fatal weakness, discovered by two Microsoft cryptographers in 2007, was engineered by the agency. The N.S.A. wrote the standard and aggressively pushed it on the international group, privately calling the effort “a challenge in finesse.”    After some sleuthing, I'm pretty certain this is a reference to the  pseudorandom number generator scheme described in NIST SP 800-90.  The weakness is that Dual_EC_DRBG appears to contain a backdoor, and anyone who knows the backdoor can totally break the PRNG.  The weakness was first described in  and was subsequently .  As a consequence, there are now good reasons to suspect that Dual_EC_DRBG contains a NSA backdoor, and the NSA might be able to spy on anyone who is using Dual_EC_DRBG.  My questions:   Who uses Dual_EC_DRBG? Do any commercial products use Dual_EC_DRBG? Does anyone use it?