As far as I understand the number of protons in a nucleus is limited because Coulomb forces grow faster with the number of protons than the nuclear force. So alpha/cluster decay limits the size in this case.  But why can't we have nuclides with very numbers of neutrons? Is this limited by beta- minus decay?
In basic chemistry, we are taught that an atom has roughly the same number of neutrons and number of protons, this doesn't seems to hold for larger atoms, but it is always roughly proportional (i.e. you seldom find an atom with 100 protons but 1 neutron, that just does not happen). Why is that?
Find four groups of order 20 not isomorphic to each other. Is there a quicker way to turn on WiFi Hotspot? is there a way to automate (or at least reduce the number of steps) to turn on or turn off the WiFi hotspot on my Galaxy 3.  I have to    unlock  press the menu button  press settings press More Settings Tethering and portable hotspot Slide portable hotspot on. Uncountable chain of subsets of $\mathbb N$ Search among posts you've voted for Related posts:    These posts are different from mine in that they merely ask for the &quot;votes&quot; tab back or ask if it is at all possible to get such information, while I propose how to implement this as a search feature. Background I recently found myself facing a problem very similar to one that I had solved before. I remembered that I found the solution on SO and I remembered upvoting the post containing the solution. I wasn't able to find that particular post by just searching with relevant keywords. It would have been nice if I could search only among the questions I have voted on. I searched on meta and found that there had been a tab for looking at what you've voted on, but that it was removed due to lack of interest. This is understandable, since just listing the hundreds/thousands of posts you've voted on isn't particularly useful. Proposal What I want is to be able to search for posts I've voted on similarly to the way I'm able to search on my posts within a specific tag. For instance: user:310121 [iphone] apple  This will return all my posts tagged iPhone, where I mention Apple. This is brilliant. This is just how I want search to work. Now what I want to do is to extend this to include votes. The exact syntax isn't relevant, but I had to make one up to show you what I mean: To show all posts you've voted on: user:310121 {votes}  To show all posts you've upvoted: user:310121 {upvotes}  To show all posts you've downvoted: user:310121 {downvotes}  You could probably omit the the user part, since you're only allowed to see your own votes. (Unless it's desirable to be able to look at other peoples votes. Maybe you should be allowed to do this if you have enough rep? Well, that's another discussion.) I guess that even if you're allowed to see other peoples votes it would make sense to display your own votes if the user part is omitted. So in my case I could have done the following search and found the post I was looking for: {upvotes} keyword  Lastly I just want to suggest that clicking on your vote count will work just like clicking on a tag. If I click on a tag in my profile the following search will be done: user:310121 [tag]  So if I click on my upvote count the following search should be made: user:310121 {upvotes}  The same goes for downvotes: user:310121 {downvotes}  This would be a very useful feature and it wouldn't be intrusive in any way. The users that don't care for this feature might never know that it's there. And just for the record the favorite system doesn't replace this feature. Smooth transition between two materials QGIS locked into fullscreen mode on Ubuntu 12.04 No crash in this case, but I made the mistake of toggling to fullscreen mode on my netbook running Ubuntu 12.04. It's now impossible to escape , and it seems to have disabled the popout unity launcher as well. Steps I've already taken:   Alt-Tab to move to a different program, then back - QGIS remains in fullscreen Alt-V, Ctrl-F and F11 get no response I've unistalled QGIS, deleted the /.qgis/ profile data folder, and reinstalled. Still launches fullscreen   To add to the weirdness, it now launches - still in fullscreen - into a different workspace than the active one.  I realize this has the sound of a Unity problem, but it's just this program that has a malfunctioning UI.  Thanks to all the crew; this in no way changes my opinion of QGIS as an essential tool. Linear regression prediction interval If the best linear approximation (using least squares) of my data points is the line $y=mx+b$, how can I calculate the approximation error? If I compute standard deviation of differences between observations and predictions $e_i=real(x_i)-(mx_i+b)$, can I later say that a real (but not observed) value $y_r=real(x_0)$ belongs to the interval $[y_p-\sigma, y_p+\sigma]$ ($y_p=mx_0+b$) with probability ~68%, assuming normal distribution?  To clarify:  I made observations regarding a function $f(x)$ by evaluating it a some points $x_i$. I fit these observations to a line $l(x)=mx+b$. For $x_0$ that I did not observe, I'd like to know how big can $f(x_0)-l(x_0)$  be. Using the method above, is it correct to say that $f(x_0) \in [l(x_0)-\sigma, l(x_0)+\sigma]$ with prob. ~68%? test class with Batch and Callout I have a problem with FeedItems in my Test class, it's very weird behaviour Does someone explain to me why this happens?  Callout Class  public with sharing class Callout {  public static void runProccess(Case[] records) {     Database.executeBatch(new CalloutBatch(records), 10); }  public static void send(Case[] records) {     Case[] toUpdate = new Case[]{};       for (case record : records) {         HttpRequest req = new HttpRequest();         req.setEndpoint('callout:test/SOME_URL');         req.setMethod('POST');         req.setHeader('Content-Type', 'application/json');         req.setBody('');         Http http = new Http();         HTTPResponse res = http.send(req);          Map&lt;String, Object&gt; response = (Map&lt;String, Object&gt;) JSON.deserializeUntyped(res.getBody());          toUpdate.add(new Case(Id = (Id) response.get('Id'), Status = (String) response.get('Status')));     }      update toUpdate;  } }   CalloutBatch Class  global with sharing class CalloutBatch implements Database.Batchable&lt;Case&gt;, Database.AllowsCallouts{  private final Case[] records;  global CalloutBatch (Case[] records) {     this.records = records; }  global Iterable&lt;Case&gt; start(Database.BatchableContext BC) {     return records; }  global void execute(Database.BatchableContext BC, Case[] scope) {     Callout.send(scope); }  global void finish(Database.BatchableContext BC) { } }   Test Class  @IsTest  private class CalloutTest { @IsTest static void shouldReaciveData() {     String status = 'Closed';     Case caseRecord = new Case(Type = 'Web', Status = 'New');     insert caseRecord;      //insert new FeedItem(ParentId = caseRecord.Id, Visibility='AllUsers', Type = 'TextPost', Body = '');      System.assertEquals(0, [SELECT Count() FROM Case WHERE Id = :caseRecord.Id AND Status = :status]);      Test.startTest();     Test.setMock(HttpCalloutMock.class, new CalloutTestMock(caseRecord.Id, status));     Callout.runProccess(new Case[]{caseRecord});     Test.stopTest();      System.assertEquals(1, [SELECT Count() FROM Case WHERE Id = :caseRecord.Id AND Status = :status]); } }   Mock Class  public with sharing class CalloutTestMock implements HttpCalloutMock {  private Id recordId; private String status;  public CalloutTestMock(Id recordId, String status) {     this.recordId = recordId;     this.status = status; }  public HTTPResponse respond(HTTPRequest req) {     HttpResponse response = new HttpResponse();      response.setStatusCode(200);     response.setBody('{"Id": "' + recordId + '", "Status": "' + status + '"}');      return response; } }   This code works, but when I uncomment insert FeedItem in Test Class I receive an error message:     System.CalloutException: You have uncommitted work pending. Please commit or rollback before calling out   Class.Callout.send: line 23, column 1   Class.CalloutBatch.execute: line 20, column 1   FeedItem doesn't have an impact on this functionality, (I don't have any Process Builders, triggers etc. on FeedItem object) Are \( and \) preferable to dollar signs for math mode? Along the lines of , what reasons are there (if any) to favor \( ... \) over $ ... $? Is the set of real matrices diagonalizable in $\mathcal M_n(C)$ dense in the set of all companion matrices? What is the command to minimize the gnome terminal? How can I minimize the Terminal window using a command? For example: I use the clear command to clear the terminal output, which command can I have to use to minimize the terminal window? Seems like this is the most powerful weapon of all: transport your enemy into a bulkhead, planet, etc. Transport your enemy's ship inside a planet, etc.  Is there some technical reason that it can not be used this way? There is a question I have based on the fact: If you take a quadratic polynomial with integer coefficients, take the set $\{1,2,3,4,5,6,7,8\}$, make a partition $A=\{1,4,6,7\}$, $B=\{2,3,5,8\}$, and then evaluate the polynomial with the elements of each set you got an equality.  If now with a cubic polynomial and the set $\{1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16\}$, how to pick a suitable partition that accomplish the same fact? I mean is there a general formula for bigger degree? I have a set of surround speakers, connected to my iMac through the headphone jack. I use a switch to control what goes to the speaker set (iMac, iPod, or MacBook/aux). So that I don't have to be constantly unplugging and replugging, I leave the audio cable in the iMac's audio port. This means that when I'm listening to something from another source, I can't hear anything from the iMac unless I unplug the cable.  Is there a way to force sound to come out of the internal speakers, even if there's something in the audio out port? How do I use reflection to invoke a private method? There are a group of private methods in my class, and I need to call one dynamically based on an input value. Both the invoking code and the target methods are in the same instance. The code looks like this:  MethodInfo dynMethod = this.GetType().GetMethod("Draw_" + itemType); dynMethod.Invoke(this, new object[] { methodParams });   In this case, GetMethod() will not return private methods. What BindingFlags do I need to supply to GetMethod() so that it can locate private methods? So here is what i want to pull : mmcblk0 whith it's size 15.7 GB.  C:\adb&gt;adb shell shell@android:/ $ su su shell@android:/ # fdisk -l /dev/block/mmcblk0 fdisk -l /dev/block/mmcblk0  Disk /dev/block/mmcblk0: 15.7 GB, 15758000128 bytes 1 heads, 16 sectors/track, 1923584 cylinders Units = cylinders of 16 * 512 = 8192 bytes   This is what I tried:  C:\adb&gt;adb shell su busybox cat /dev/block/mmcblk0 &gt; C:\1.bin   I only have 1KB output with content inside said "unknown id". Also tried with pull but seems also doesn't work.  What should I do to get this 15.7 GB mmcblk0  ? Fermat's Last Theorem for Gaussian Integers (excluding the integers or  same pure imaginaries) I am investigating solutions to Fermat's equation $$x^n + y^n = z^n$$ with $x,y,z$ in the Gaussian integers, excluding integers and pure imaginaries.  I have found out that there are only trivial solutions for the $n=3$ and $n=4$ cases, e.g. .   I would be grateful if you let me know of the current status or if it is already a theorem. Why isn't my Gravatar image updating? invalid conversion from ‘const char*’ to ‘char’ Shortcuts in Objective-C to concatenate NSStrings Are there any shortcuts to (stringByAppendingString:) string concatenation in Objective-C, or shortcuts for working with NSString in general?  For example, I'd like to make:  NSString *myString = @"This"; NSString *test = [myString stringByAppendingString:@" is just a test"];   something more like:  string myString = "This"; string test = myString + " is just a test";