i have seen some analogies of spin using playing cards but i am struggling to grasp the concept due to this making no sense in terms of playing cards
I often hear about subatomic particles having a property called "spin" but also that it doesn't actually relate to spinning about an axis like you would think. Which particles have spin? What does spin mean if not an actual spinning motion?
Often assignments (or even papers) have a word count limit. That is not a big deal when using Word, but I don't know how to do that using LaTeX. My solution has been so far to compile the document and then do a rough word count of my pdf file, sometimes even copying the contents of the pdf file and pasting in Word to get a mostly correct Word count.  Is there any tool (maybe even an online tool), package, script or software to do that directly from my .tex document and still get the right word count (i.e., ignore commands, equations, etc)? Is it possible to use JS to open an HTML select to show its option list? Is it possible to use JavaScript to open an HTML select to show its option list? problems with ellipse TikZ I'm working on a mac, I use the package TikZ and it works. But I have problems when I want use ellipse or diamond ex :  \documentclass{article} \usepackage{graphicx} \usepackage{tikz} \begin{document} \begin{tikzpicture} \node[ellipse] {Ellipse}; \end{tikzpicture} \end{document}   If somebody could help me thank you ! Merge files based on matching of first column I have a realy strange problem in Ubuntu 11.10. I have by accident my password set to empty. If I wan't to install software now the system asks for a password, but I haven't one anymore. If I enter my old password it sais it's wrong and if I leave it empty it also does. Now I wan't to set my password back, but the system asks for the old password before I can change it. That password doesn't exist, so I can't do anything anymore! Can someone help me please? In languages like Java and C#, strings are immutable and it can be computationally expensive to build a string one character at a time.  In said languages, there are library classes to reduce this cost such as C# System.Text.StringBuilder and Java java.lang.StringBuilder.  Does php (4 or 5; I'm interested in both) share this limitation?  If so, are there similar solutions to the problem available? When should I use # and = in ASP.NET controls? Create a directly-executable cross-platform GUI app using Python How fast does the sequence $y_t$ defined by $y_{t+1}=y_t(1-y_t)$ decay to zero? The question is in the title; I'm looking for the exact decay rate. Naturally, assume the starting point $y_0$ belongs to $(0,1)$.   This is motivated by one of the answers to . i want to create new event in SharePoint calendar list in which I have some custom columns,i tried below code but it is not working      function bookingRoomForMeeting() {         var ctx = new SP.ClientContext(appWebUrl);//Get the SharePoint Context object based upon the URL           var list = ctx.get_web().get_lists().getByTitle("MyCalendarList"); //Get the List based upon the Title         var listCreationInformation = new SP.ListItemCreationInformation(); //Object for creating Item in the List         listItem = list.addItem(listCreationInformation);         listItem.set_item('Title', $("#txt_Title").val());         var date = $("#txt_startTime").val();         var dateTime = moment(date, 'DD/MM/YYYY HH:mm a').format("MM/DD/YYYY HH:mm a");         listItem.set_item('EventDate', dateTime);         var enddate = $("#txt_endTime").val();         var enddateTime = moment(enddate, 'DD/MM/YYYY HH:mm a').format("MM/DD/YYYY HH:mm a");         listItem.set_item('EndDate', enddateTime);         listItem.set_item('EmailId1', $("#txt_EmailId1").val());         listItem.set_item('EmailId2', $("#txt_EmailId2").val());         listItem.update();         ctx.load(listItem);         ctx.executeQueryAsync(             Function.createDelegate(this, success),             Function.createDelegate(this, fail)            );     } function success() {     alert("Completed"); } function fail() {     alert("operation failed"); }   list am using is SharePoint hosted app list,can any one tell me where am going wrong? What does $(command) & do? I saw the following syntax in a bash script:   &gt;$(command) &amp;   I know that the ampersand &amp; at the end makes a command run in the background, but I have never seen it in combination with the dollar sign plus the brackets around the command.  What does it do? Page Object Model or External property file for Selenium Object Repository I am a beginner in Selenium WebDriver (Java with TestNg). I'm trying to create a framework of my own.  My question here is what would be the better option to store my objects (basically all the webelements of my website under test), Page Object Model or External Property file? Why? Is there a better method than those? Please help. Infectious chicken pox My 21 year old son has chicken pox and has been home for a few days now. The spots are just starting to crust over.  I work with elderly people but have had chicken pox as a child - should I carry on working while he is here (hes usually away at Uni) and infectious? What are the biggest differences between Reversal Rings, Extension Tubes and Macro Lenses? As far as I understand all three options help you do macro photography but are their other reasons for having the three different items? I figured reversal rings and extension tubes were just for the low cost but with additional more expensive features being added to the two options it seems there may be certain situations for each type? What are their biggest differences and advantages over each other?   Are there situations where you would have one over the other? Do all three options have the same "wafer thin" depth of field?  Do they all suffer from the same light loss? Do any of them affect your photos more negatively than the others? Can I achieve the same magnification with rings and tubes that I can with proper lenses? Would you ever combine these options together or would there be no need for that?   I ask because I recently bought a cheap extension tube and reversal ring and I'm trying to get a better overall understanding of each. I tend to use the extension tube a lot more, because I can put it on my 70-200 and have a workable distance between subject and lens.  This photo was taken with 49mm of extension tube on the 70-200 I believe which may be greater than 1:1. Would it be sharper with a macro lens?       on 500px What's the most efficient way to select the last n rows in a table without changing the table's structure? What's the most efficient way to select the last n number of rows in a table using mySQL? The table contains millions of rows, and at any given time I don't know how large the table is (it is constantly growing). The table does have a column that is automatically incremented and used as a unique identifier for each row. Is there a simple method of parsing XML files in C#? If so, what? Creating and configuring .bash_profile I was setting path for anaconda. an answer to a question  has the following solution. I searched for .bash_profile, but I can't seem to find it. How do I setup this file and get it to run on startup? Replacing strings in files based on certain search criteria is a very common task. How can I    replace string foo with bar in all files in the current directory? do the same recursively for sub directories? replace only if the file name matches another string? replace only if the string is found in a certain context? replace if the string is on a certain line number? replace multiple strings with the same replacement replace multiple strings with different replacements Total of attribute field of point layer per polygon layer I have a polygon shapefile of many lakes, I also have a point shapefile of locations on those lakes where fish were caught.  The point shapefile contains the attributes: Fisherman_iD, Fish_Caught, Lat, Long.  The polygon shapefile contains the attributes Lake_name, Points_per_polygon(PNTCNT)  Each point obviously has differing entries under the fish_caught field.   What I want to get is the average fish caught per lake (polygon).  So I need to have a total number of fish caught, per individual polygon, and then I can divide that by the PNTCNT file I create using the Points in a Polygon tool.  Ideas? I am relatively new to QGIS. Stuck on two valid squares in minesweeper How to solve? The 1 indicates that ones of the two questioned flags is a mine and 3 also indicates the same. How to choose logically between any one of them?