Looking for 3 examples of prisoners of war being incorporated into the conquering army

Question: When POWs were captured, they were either executed, exchanged, put into slavery or sometimes incorporated into the enemy army. I'm trying to find a few examples (3 would do) of the last category. Would their loyalty an issue in such a case?
Comment: @T.E.D. The treatment of POWs has been a major point in Islamic jurisprudence for a very long time, to quote just one example
Comment: Quite a few recently conquered German tribes (Gepids, Franks, Ostrogoths) were in Attila's army at Orleans. They didn't really have the concept of a POW in ancient times though.
Comment: Look up the possible story of Yang Kyoungjong , he was Korean and served in the Japanese army, was captured then fought for the Soviet union and then was captured again by the germans and fought for them till he was captured by the allies.
Answer: During WW2 you had:

Russian Liberation Army.
These soldiers fought for the Germans and consisted out of former POWs.
British Free Corps. These fought also on the side of the Germans and partialy consisted out of British POWs and volunteers.
National Committee for Free Germany. While technically not an army, but you may consider their efforts an attempt to destabilize the enemy army. Essentially it was a group of communist and POWs that took efforts to bring their ideals to the German front.
Comment: @Daud - There wasn't even the really the concept of a POW until the late 1600's, so "pre-19th Century" cuts it down to only about 1/3rd of its possible history to draw from.
Comment: Thanks. If possible, can you add an example from pre-19th century?
Comment: Vlasov's Russian Liberation Army was not allowed to fight till the very end of the war. They were used as noncombatant help forces mostly.
Answer: In the American Civil War, both sides recruited from their POWs.  Most entered US service and smaller number of Union POWs entered Confederate service.  See
https://en.wikipedia.org/wiki/Galvanized_Yankees
Answer: In the Russian Civil war of 1918-21, the incorporation of prisoners was so standard operation that some people changed sides many times. They had to choose from being shot or dying from starvation in the camp, against maybe remaining alive by means of "voluntary" incorporation. Such mass incorporations happened practically after every battle. Not three examples, but millions of them.


How to configure Microsoft Bot Framework with Office365 channel

Question: I build an MS Bot and published the bot to the Portal. Now i would enable and configure the email-channel with my outlook.com email address for my bot. I use the Office 365 Home Abbonement.
I get the failure "Unable to validate the given credentials" and i'm sure that my password is correct.
Have i do same configurations on my outlook account?
Thank you
Answer: You have to use business office.


Formatting Embedded Google Spreadsheet

Question: I am trying to insert a google spreadsheet to my website that can refresh when updated that does not contain the sheet name or title header from google.  I am able to get the spreadsheet linked but the formatting of the table is not what I would like.  Please help me prevent the tab and header from showing on my table.
Answer: You could create a special tab which contains the output in the format you need to embed, however this will not solve the header problem. Best thing you can do is to create a special tab, without and name the tab just a dot  example

Formatting Embedded Google Spreadsheet


L200C regulated power supply - maximum current

Question: Hi
I need to know what is the L200C maximum current. The datasheet says it's internally limited. Am not quite sure what this means.
Answer: It's in the data sheet (page 4) - peak short circuit current is 3.6 A, with pins 2 and 5 shorted. It'll probably go into thermal shutdown if you try it, unless it has a large heatsink.
Comment: ah OK! Why didn't they write it on same page grr· I ripped a heat sink out of an old AT power supply awhile back. Smart thinking!
Comment: The 3.6 A are available only when the voltage difference between input and output is 14 V, so that too needs to be taken into account.
Answer: On the first page of the data sheet, it is said that it has adjustable current up to 2 A.
Another very important thing is note 1 on the page 4. It says that up to 2 A can be provided if the difference between input and output is less than 20 V (this came back and bit me couple of times).
Figure 3 on page 4 also provides interesting information. It shows relation between voltage difference, junction temperature and output current.


System restore - System crash

Question: I had a problem with my Outlook Express program. I tried everything with it, but I couldn't start it (OE encountered program, so it will close). I tried to copy out the deleted e-mails.dbx from the folder to the desktop, but it has crashed all of my things, which was on the desktop. Then I tried system restore (from the start menu), but it has crashed my computer. Now when it tries to get to the Welcome screen, it is everytime restart. What can I do? Please help me!
Answer: The first and most important thing for you to do is back up all your important files before you do anything else.
It sounds to me like your Hard Drive may be dying.  In a situation like this it is almost always better to back up and be safe regardless of whether or not the drive is bad.  Basically, it is better to be safe than sorry.
So here are a few things that I would try, before doing any sort of Windows troubleshooting:

Attempt booting into safe mode, at least initially, to recover the files.  I wouldn't try to do this more than a few times because it potentially could be causing the health of the HDD to be deteriorating further.
If you are not able to get the drive to boot in order to copy your files off, try booting to a Linux Live CD like Knoppix and attempt to recover data that way.
There are tools out there on the internet to check if this is true or not, my personal favorite is one called Drive Fitness Test.  Download and burn that to a CD if you have another working computer.  Run this tool on the computer that is crashing to determine if the drive is actually going bad.

System restore - System crash


'I brought them at my home' or 'I brought them to my home'?

Question: I want to know which preoposition should I use before the word 'home'.
Comment: Why do you feel like you have to use any preposition? "I brought them home" is a perfectly good sentence.
Comment: "I brought them to my home" works. The other one is completely incorrect.
Comment: Well, it might not be incorrect; it depends on the circumstances. But it's almost certainly incorrect. @Jairin, you chose the right tag ("prepositions") but without knowing what the sentence is supposed to mean, it's impossible to say definitively which preposition is correct. Could you edit your question to add the circumstances which led to your "I brought..." sentence? We might then be able to determine exactly which preposition is required.
Comment: @Andrew: I think we can safely assume OP has no idea how ***at*** would change the meaning. In a pretty weird way, actually - my first attempt to contrive a valid context ended with me deciding it would be easier to assume the speaker meant ***bought***, not ***brought***. In light of that I think the question belongs on ELL, not here.
Comment: I see no case where **at" would work in English here. Brought them to my home or brought them home.
Comment: Possible duplicate of [Why do people say "I am home" instead of "I am at home"?](http://ell.stackexchange.com/questions/84703/why-do-people-say-i-am-home-instead-of-i-am-at-home)
Answer: You've probably read or heard expressions like "I'm at John's house right now" or "Everyone is at my house today."
However, even though it may seem logical, you can't say brought X at home.  The preposition at doesn't work with bring in the sense of identifying a destination location.
It sounds like you are trying to say where the event or action of bringing occurred, as opposed to the destination place of the bringing.  And that may only somewhat work in some limited circumstances where context fills in the to or for part of bring, but not very well:

Sally needs to bring candy for everyone this time.  I brought two candy bars at the game last time, so why do I have to do it again?  (I brought two candy bars for everyone at the game last time).

So, before home you want to use to or in.
Answer: One

brings something to somewhere
I bring my lunch to work.
  We brought the tour group to the attraction.

and one

does something at someplace
I write programs at work.
  She got her hair cut at the salon.

Your example should be

I brought them to my home.

or more simply

I brought them home.
Comment: What if I want to say that I brought them to the area around my home or in a point near my home. Can I say I brought them at my home or what?
Comment: You could use "I brought them *around / near / beside / next to / close to / by*  my home" for a location close to your home.


Can a player invite a villager from MY campsite to THEIR island?

Question: I have Bam in my campsite but I don't think I want to invite him into my island. Is there a way for other people to come to my island and invite someone from my campsite to their island?
Answer: Unfortunately not. You would need to invite Bam to live on your island and then have him trigger to move out (either by ignoring him or via Amiibo) as other players can only acquire villagers on your island if they're 'in boxes' (moving out).


TexShop Find All missing

Question: Earlier versions of TexShop had a "Find All" button in the find panel (along with "Replace All", "Find Next", etc), which popped up a list of all the instances of the search string, with line numbers.  How do I enable / get back this button/option in the newest version of TexShop?  Find All is an essential operation, and despite attempts to modify my workflow, the absence of the feature is a persistent problem---not just an inconvenience but it actually makes complex find operations in large projects infeasible in TexShop.  I can't imagine the rationale for eliminating this basic feature, so I hope it is just buried somewhere for activation.  Thanks.
Comment: What version are you using? TeXShop3.95 does have `Replace All` and Find Next as `Next`. Use Command F to pop up the `Find` panel. Not sure about `Find All` though.
Answer: TeXShop has two Find panels, an Apple one, which is quite simple (and doesn't have a Find All button) and and OgreKit one, which has many more functions, including regular expression matching, and also has a Find All button.  The simple find panel looks like this:

The OgreKit panel looks like this:

You can change which panel is used in the TeXShop preferences (restart of TeXShop required to show the change).
There's also the possibility of using the Apple Find bar, which is even more limited:

TexShop Find All missing


Static Methods in an Interface/Abstract Class

Question: First off, I understand the reasons why an interface or abstract class (in the .NET/C# terminology) cannot have abstract static methods.  My question is then more focused on the best design solution.
What I want is a set of "helper" classes that all have their own static methods such that if I get objects A, B, and C from a third party vendor, I can have helper classes with methods such as

AHelper.RetrieveByID(string id);
AHelper.RetrieveByName(string name);
AHelper.DumpToDatabase();

Since my AHelper, BHelper, and CHelper classes will all basically have the same methods, it seems to makes sense to move these methods to an interface that these classes then derive from.  However, wanting these methods to be static precludes me from having a generic interface or abstract class for all of them to derive from.
I could always make these methods non-static and then instantiate the objects first such as

AHelper a = new AHelper();
a.DumpToDatabase();

However, this code doesn't seem as intuitive to me.  What are your suggestions?  Should I abandon using an interface or abstract class altogether (the situation I'm in now) or can this possibly be refactored to accomplish the design I'm looking for?
Answer: If I were you I would try to avoid any statics. IMHO I always ended up with some sort of synchronization issues down the road with statics. That being said you are presenting a classic example of generic programming using templates. I will adopt the template based solution of Rob Copper presented in one of the posts above.
Answer: Looking at your response I am thinking along the following lines:

You could just have a static method that takes a type parameter and performs the expected logic based on the type.
You could create a virtual method in your abstract base, where you specify the SQL in the concrete class. So that contains all the common code that is required by both (e.g. exectuting the command and returning the object) while encapsulating the "specialist" bits (e.g. the SQL) in the sub classes.

I prefer the second option, although its of course down to you. If you need me to go into further detail, please let me know and I will be happy to edit/update :)
Comment: IMHO: First option would be better off being generic so type inference can be used which is even better.
Answer: For a generic solution to your example, you can do this:
public static T RetrieveByID<T>(string ID)
{
     var fieldNames = getFieldNamesBasedOnType(typeof(T));
     QueryResult qr = webservice.query("SELECT "+fieldNames + " FROM "
                                     + tyepof(T).Name
                                     +" WHERE Id = '" + ID + "'");
     return (T) qr.records[0];
}

Comment: +1. I do this in several querying libs, especially the ones that flow through to web services.
Answer: I personally would perhaps question why each of the types need to have a static method before even thinking further..
Why not create a utlity class with the static methods that they need to share? (e.g. ClassHelper.RetrieveByID(string id) or ClassHelper<ClassA>.RetrieveByID(string id)
In my experience with these sort of "roadblocks" the problem is not the limitations of the language, but the limitations of my design..
Answer: How are ObjectA and AHelper related? Is AHelper.RetrieveByID() the same logic as BHelper.RetrieveByID()
If Yes, how about a Utility class based approach (class with public static methods only and no state)
static [return type] Helper.RetrieveByID(ObjectX x)

Answer: You can't overload methods by varying just the return type.
You can use different names:
static AObject GetAObject(string id);
static BObject GetBObject(string id);

Or you can create a class with casting operators:
class AOrBObject
{
   string id;
   AOrBObject(string id) {this.id = id;}

   static public AOrBObject RetrieveByID(string id)
   {
        return new AOrBObject(id);
   }

   public static AObject explicit operator(AOrBObject ab)
    {
        return AObjectQuery(ab.id);
    }

   public static BObject explicit operator(AOrBObject ab)
    {
        return BObjectQuery(ab.id);
    }
}

Then you can call it like so:
 var a = (AObject) AOrBObject.RetrieveByID(5);
 var b = (BObject) AOrBObject.RetrieveByID(5);

Answer: In C# 3.0, static methods can be used on interfaces as if they were a part of them by using extension methods, as with DumpToDatabase() below:
static class HelperMethods
 {  //IHelper h = new HeleperA();
    //h.DumpToDatabase()
    public static void DumpToDatabase(this IHelper helper) { /* ... */ }

    //IHelper h = a.RetrieveByID(5)
    public static IHelper RetrieveByID(this ObjectA a, int id)
     {
          return new HelperA(a.GetByID(id));
     }

    //Ihelper h = b.RetrieveByID(5)
    public static IHelper RetrieveByID(this ObjectB b, int id)
     {
          return new HelperB(b.GetById(id.ToString()));
     }
 }

Answer: How do I post feedback on Stack Overflow?  Edit my original post or post an "answer"?  Anyway, I thought it might help to give an example of what is going on in AHelper.RetrieveByID() and BHelper.RetreiveByID()
Basically, both of these methods are going up against a third party webservice that returns various a generic (castable) object using a Query method that takes in a pseudo-SQL string as its only parameters.
So, AHelper.RetrieveByID(string ID) might look like

public static AObject RetrieveByID(string ID)
{
  QueryResult qr = webservice.query("SELECT Id,Name FROM AObject WHERE Id = '" + ID + "'");

  return (AObject)qr.records[0];
}

public static BObject RetrieveByID(string ID)
{
  QueryResult qr = webservice.query("SELECT Id,Name,Company FROM BObject WHERE Id = '" + ID + "'");

  return (BObject)qr.records[0];
}

Hopefully that helps.  As you can see, the two methods are similar, but the query can be quite a bit different based on the different object type being returned.
Oh, and Rob, I completely agree -- this is more than likely a limitation of my design and not the language. :)
Answer: Are you looking for polymorphic behavior?  Then you'll want the interface and normal constructor.  What is unintuitive about calling a constructor?  If you don't need polymorphism (sounds like you don't use it now), then you can stick with your static methods.  If these are all wrappers around a vendor component, then maybe you might try to use a factory method to create them like VendorBuilder.GetVendorThing("A") which could return an object of type IVendorWrapper.
Answer: marxidad Just a quick point to note, Justin has already said that the SQL varies a lot dependant on the type, so I have worked on the basis that it could be something completely different dependant on the type, hence delegating it to the subclasses in question. Whereas your solution couples the SQL VERY tightly to the Type (i.e.  it is the SQL).
rptony Good point on the possible sync issues with statics, one I failed to mention, so thank you :) Also, its Rob Cooper (not Copper) BTW ;) :D ( EDIT: Just thought I would mention that in case it wasn't a typo, I expect it is, so no problem!)


How is WordPiece tokenization helpful to effectively deal with rare words problem in NLP?

Question: I have seen that NLP models such as BERT utilize WordPiece for tokenization. In WordPiece, we split the tokens like playing to play and ##ing. It is mentioned that it covers a wider spectrum of Out-Of-Vocabulary (OOV) words. Can someone please help me explain how WordPiece tokenization is actually done, and how it handles effectively helps to rare/OOV words?
Comment: This question has been answered [here](https://stackoverflow.com/a/55416944/3711601). I'm copying the answer here as well. WordPiece and BPE are two similar and commonly used techniques to segment words into subword-level in NLP tasks.
In both cases, the vocabulary is initialized with all the individual characters in the language, and then the most frequent/likely combinations of the symbols in the vocabulary are iteratively added to the vocabulary. Consider the WordPiece algorithm from the [original paper](https://static.googleusercontent.com/media/research.google.com/en//pubs/archive/37842.p
Comment: The URL is broken. Here the [corrected one](https://static.googleusercontent.com/media/research.google.com/en//pubs/archive/37842.pdf).
Comment: Here you go... https://www.youtube.com/watch?v=zJW57aCBCTk
|
I've recently started following this guy. He has a very nice way of explaining such concepts.
Answer: WordPiece tokenization is a type of subword tokenization. Subword tokenization is a technique for splitting words into smaller units, called subwords, that are still meaningful. This is in contrast to traditional word tokenization, which simply splits words on whitespace or punctuation.
WordPiece tokenization works by first creating a vocabulary of subwords. This vocabulary is created by iteratively merging the most common subwords together until the desired vocabulary size is reached. The merging process is done in a way that minimizes the information loss.
When a word is tokenized using WordPiece, it is first pre-tokenized into words by splitting on whitespace and punctuation. Then, each word is tokenized into subwords using the vocabulary. If a word is not in the vocabulary, it is split into subwords using the merging process.
WordPiece tokenization is effective for handling rare/OOV words because it allows the model to learn the meaning of words even if they are not in the vocabulary. This is because the model can learn the meaning of a word from the subwords that make up the word.
For example, the word "playing" is not in the vocabulary of a WordPiece model. However, the model can learn the meaning of the word by learning the meaning of the subwords "play" and "ing".
WordPiece tokenization is a powerful technique for handling rare/OOV words in NLP models. It is used in many popular models, such as BERT, DistilBERT, and Electra.


How to get wall plugs out

Question: Anyone know how to get a super old wall plug out? My husband and I are redoing our house we just bought and have multiple all over our bathroom. The house was built in 1958 so I don't know if that makes a difference in what kind of wall plugs were used. I looked up how to do it. Did it the way it shows (by screwing in a screw and grabbing it with pliers to pull out) and it took a huge chunk of the wall with it because it has a really big metal back behind the wall. I tried to add a picture but it's not allowing me to.
Comment: Upload your pics to imgur.com and post the `share` links here in a comment. Someone will embed them for you.
Comment: I do hope you are not talking about electrical outlets.
Comment: sounds concerning...  no way to answer this without pictures
Comment: Can you post a photo? I'm still trying to figure out if we're talking about some sort of mounting fixing, or about electrical receptacles(!!!!!)
Comment: If it is a receptacle after you turn the power off. Remove the face plate. Then there are 2 screws one at top and bottom, remove those. Next where the screws went in there may be a small ear or circle to the left and right above the screw. Use a box cutter and cut around this metal piece, all the years of paint and or wall paper get put over the "yoke strap" and it will tear the wall if not cut. Then pry up the thin metal may be stuck because of paint but they break loose with a little force. If you don't cut the paint can peal quite a chunk up look at a new receptacle or switch for the shape.
Comment: There are a half dozen different styles of wall anchors.  The technique used depends on the specific anchor design.
Comment: If it's a wall plug with a big back could just hammer it into the wall to fall down the back, leaving a small hole
Answer: I believe you are describing  hollow wall anchors. Molly screw is a common brand name that has come to be reference for almost any hollow wall anchor. I think you have half the removal process. You need to install a screw then gently tap it with a hammer. This will straighten out the insert allowing it to come out thru a hole slightly larger than the original.
Comment: You'd do well to find an anchor that hasn't been used. Then you can see how it might work in reverse. And, be able to work out what depth the screw needs to be knocked in.

How to get wall plugs out


Build JSON array from JSON items

Question: The client browser sends JSON data to the server, the server saves this raw JSON information (String) in a history array (Ruby array).
When another user asks for this history, the server sends the information as a JSON array.
I can't simply use history.to_json here since this will convert the already JSON objects inside the array to JSON objects.
An alternative would be parsing the JSON data and inserting that data as a Ruby object to the array, and then converting the entire array to JSON when it is asked, but this seems like a waste of parsing the received data just so I can later on convert it again to JSON.
I was looking for a JSON builder for Ruby but couldn't find one. Anyone got a hint?
Answer: If you're passing the JSON string back to a client, could you not just pass the string back and parse it in javascript using JSON.parse method?

Build JSON array from JSON items


Approach math prof with proof

Question: I received a master's in math a long time ago and now I am thinking I would like to get a Ph.D. Since I have not been in school, would it be ok to approach a professor I would like to work with by proving a small thing from one of his papers he says is "work to be done" and emailing to him? I already have a proof. Would this add value for him or would he be annoyed? Many people here say you need letters from professors but I have no way for that. This is in America.
Comment: Why do you want a PhD? You seem to phrase it quite casually, while getting a PhD needs quite some dedication for quite some time.
Comment: How small is this proof? 3 lines? Half a page? If you proved something really nontrivial and substantial that took some clever ideas and several pages of calculations, I think this could be a good start for a conversation and may be appreciated, but for something really small I don't think it would get you very far.
Answer: In most math PhD programs in the US [I believe most turns to "all" as you approach the pure side of the mathematical spectrum] students are admitted and funded by an admissions committee representing the department as a whole, not primarily by the recommendations (or funding) of individual faculty members.
So if you are contemplating showing this work to a professor in the hope of getting admitted to that department's PhD program: that is not a very direct route.  If you are applying to that department anyway, then by all means contact all faculty members with whom you feel a connection and especially in the situation you described.  You should also mention this work in your application, e.g. in your statement of purpose.  That way it is likely that the admissions committee will contact the faculty member and ask about your case.  If you have correctly answered a question from one of their papers [and especially if this answer has not already appeared elsewhere in the literature; it would be a good idea to try to find that out], then they are certainly likely to put in a good word for your application.  However, you should understand that students are being judged mostly on the quality of their coursework, the present state of their mathematical knowledge and their potential for future achievements, and not very much on their own research achievements [e.g. because it is common for top candidates to have no research achievements].  So you should not expect this to offset any major weaknesses in your application.
By the way, having no letters of recommendation is a major weakness: in fact, it will cause your application not to be considered at most programs I know.  Maybe your idea is rather to get into a correspondence with this professor that will allow them (in time) to write a letter for you?  If so: yes, that could work.
By the way, I am currently the Graduate Coordinator [and ex officio chair of the graduate admissions committee] of the mathematics department at the University of Georgia.
Comment: @Elizabeth: If the research question is a significant one, the work is correct, novel and done independently by the student: yes, that sounds very good.  (The OP said this was a "small thing" described as "work to be done," so it may not be novel to the professor in question.)  If the OP has done all this then he should get a letter from the professor in his file.  If the professor thinks the achievement is significant, then such a letter will carry a lot of weight.  But IME students who have done such things are very likely to have otherwise strong applications.
Comment: I got into a CS PhD program using reference letters from industry people, because it was 25+ years after my master's degree. Might that work for Mathematics?
Comment: I'm a little surprised by this. Wouldn't answering a research question be the best possible evidence of potential for future achievements, regardless of whether it was common for top candidates?
Comment: @Patricia: It would work better than no letters at all, but at least in pure mathematics, it would probably not work very well.  One point that may not be the same as in CS: virtually all students in US math PhD departments are admitted with full funding.  A student with no letters would probably do better to enroll in a non-degree program for a few semesters, thereby to generate the requisite letters.
Answer: If he actually says that it is "work to be done", and you really have answered the question he intended to pose, he would probably be interested to hear from you.
And even if he thinks it's too small a contribution, or if you've answered a question that is different from the one he asked, you have nothing to lose by writing to him.
Answer: If the proof is correct, non-trivial, and it was not kind of handwaving "oh, you could do this too", but rather "it would be curious to do, but we have not yet" -- yes! Even if you do not have a second thought of getting a position.
It is always fulfilling to hear about someone picking up your old work. It might even give you a paper together with the Prof. But! Getting a PhD position is a bit uncoupled from fruitful cooperation, as already detailed above.
Is something like an "external" PhD position viable in your country? Basically work elsewhere (possibly part-time) and get the PhD (e.g. from that Prof.) in your free time. I don't know your circumstances, but if you already have a steady job, leaving if for a (typically underpaid) PhD position might be unfulfilling. "External" PhD is about getting the title without working at the university.

Approach math prof with proof


Translating clauses relating to observation

Question: If someone says, I saw him eat the food, how would one translate it? My best guess is Mi vidis, ke li manĝantis la manĝaĵon.
Answer: You can just say Mi vidis lin manĝi la manĝaĵon.
A close alternative is Mi vidis lin manĝantan la manĝaĵon.
Obviously you could substitute nutraĵon or a more specific word if you didn't like the repetition of manĝ-.
Your guess means "I saw that someone was (in the process of) eating the food." Iu means "someone" and the -ant- reinforces the idea that the action was ongoing. "Someone had eaten it" is Iu jam manĝis ĝin or Iu manĝintis ĝin.
Comment: To back up the suggestion with some examples, you can search for " vidis [lŝ]in [a-zĥŝĝĉĵŭ]+i\b " en tekstaro.com. There are many results, for example "Mi neniam vidis ŝin plori" from La Ŝtona Urbo.
Comment: *Mi vidis lin mangxanta" works as well; the nuance between this and "mi vidis lin mangxantan" is somewhat subtle; with the -n means I saw him, who was eating (adjective agreement), and without the -n means I saw him when he was eating (predicate nominative). I wish I could explain this a little clearer, but I'm not succeeding very well :-/.
Comment: Whoops! I'll edit my question to make the sentence match.


Is there an nontrivial function whose 'period paralellograms' are Gosper Islands?

Question: The Gosper island tiles the plane, so I'm curious if a nontrivial elliptic? function exists which would have a 'period gosper-island' instead of a period parallelogram. In this case, I'm using 'trivial' to denote a function that's got the right kind of lattice, but the Gosper island is overkill and unnecessary -- for example the derivative of the equianharmonic case: $d\wp(z;0,1)/dz$ (last image).
Comment: I don't think the question makes sense. An elliptic function has a period lattice $\Omega$, which is a subgroup of $\mathbb{C}$. There is nothing unique about "the" period parallellogram, though; it is just a convenient labeling of the equivalence classes $\mathbb{C}/\Omega$ by taking one element from each equivalence class. There is no reason, apart from convenience, why it has to be a parallellogram. Gosper islands should do just fine, though to go and pick a fractal one seems slightly perverse.
Comment: Harald -- the crux of my question is whether any functions exist whose 'canonical' fundamental domain is a Gosper island -- if you were to look at domain colored pictures of these hypothetical functions, one would say "aha, Gosper islands" instead of "aha, period parallelograms".
Comment: Dear Deoxy, your source for learning elliptic functions is definitely not the best one. But already there it's explained that fundamental domains of elliptic functions are parallelograms (quotients of $\mathbb C$ by lattices), no snowflakes. More exotic fundamental domains can be constructed for automorphic rather than elliptic functions. I wonder whether one can get fractals but tiling pictures of more regular geometric structure can be seen for example in M.Yoshida's "Hypergeometric functions, my love" (1997).
Comment: The point of Harald's comment is that there is no 'canonical' fundamental domain, at least until you provide extra data.
Comment: I wonder how the choice of fundamental domain alters the discussion of elliptic curves
Answer: The Gosper islands are a fundamental domain for the translation action of the Eisenstein integers $\mathbb{Z}[\frac{1+\sqrt{-3}}{2}]$, since the shapes can be constructed by deforming a Voronoi decomposition of the plane with respect to that lattice.  It is therefore reasonable to look for functions in the field generated by the Weierstrass $\wp$ function for the Eisenstein integers and its first derivative $\wp'$, since this field comprises all of the meromorphic functions that are periodic with respect to the lattice.
It is not clear what selection rule you want to apply to favor one function over another.  Elliptic functions do not have canonical fundamental domains, and one has to choose extra data (e.g., a basis of the lattice, and a pair of paths in the homotopy class representing the basis) to write down boundaries in the usual theory.
I suppose you may want to find a function $f(z)$ such that the boundary configuration is equal to $\{ z : |f(z)| = 1 \}$, but I am somewhat doubtful that such a function exists, simply by degree considerations.


Compact surfaces with boundary of constant negative curvature

Question: Consider a surface (with boundary) diffeomorphic to $S^1 \times [0, 1]$ and with constant negative curvature, sitting inside $\mathbb{R}^3$. All the examples I know of such surfaces are "part of" (or "cut out of", if that makes better sense) a surface of revolution (examples are the catenoid, tractricoid, etc.; O'Neill's "Elementary Differential Geometry" has a comprehensive list on page 261, Exercise 7). I was wondering, are all constantly negatively curved $S^1 \times [0, 1]$ obtained this way (that is, cut out from a surface of revolution)?
Comment: No, certainly not.  Constant negative curvature embeddings of an annulus can be constructed extremely flexible ways.  Consider taking an arbitrary knot as your embedding of $S^1 \times \{1/2\}$ and try to fatten it up to a constant negatively curved annulus.
Comment: To be a bit more explicit about Ryan's comment:  If you take any (smooth) immersed curve $c:S^1\to \mathbb{R}^3$ such that there exists a smooth unit normal $n:S^1\to S^2$ along $c$ (i.e., $c'(\theta)\cdot n(\theta)=0$ for all $\theta\in S^1$) satisfying the property that $c''(\theta)\cdot n(\theta)>0$ for all $\theta\in S^1$, then there exists an immersion $C:S^1\times[-1,1]\to\mathbb{R}^3$ such that $C(\theta,0)=c(\theta)$, $n(\theta)$ is the normal to the immersed surface at $c(\theta)$, and the induced metric has constant Gauss curvature $K\equiv=-1$.
Comment: By the way, the catenoid has negative curvature, but it is not constant. It has zero constant mean curvature. I suspect that by curvature you meant Gaussian curvature.
Comment: Yes, he means Gauss curvature.
Comment: This does not provide an answer to the question. To critique or request clarification from an author, leave a comment below their post - you can always comment on your own posts, and once you have sufficient [reputation](http://mathoverflow.net/help/whats-reputation) you will be able to [comment on any post](http://mathoverflow.net/help/privileges/comment).
Answer: There is a lot of literature on this: see Zalgaller's Geometry III in the Russian Encyclopedia: https://books.google.com/books?id=2ee_Cw4uWVIC&pg=PA158&lpg=PA158&dq=surface+in+E3+of+constant+negative+curvature&source=bl&ots=5T92bOYiq_&sig=_tG-Ovmk0L7WnOnu7Qw8jc_374Y&hl=en&sa=X&ei=CmCpVPKfIIufgwTAu4SwBg&ved=0CEgQ6AEwCQ#v=onepage&q=surface%20in%20E3%20of%20constant%20negative%20curvature&f=false
There is also the nice paper by Tunitskii (1987):
Tunitskiĭ, D. V.(2-MOSC)
Regular isometric immersion in E3 of unbounded domains of negative curvature. (Russian) Mat. Sb. (N.S.) 134(176) (1987), no. 1, 119--134, 143; translation in
Math. USSR-Sb. 62 (1989), no. 1, 121–138
53A05 (53C42)


Is it possible to see top 10% of tags that you have been active in without creating a profile on careers?

Question: How do users who don't have profile on Careers Site see the top percentage of tags they have been active in? E.g. Jon Skeet is top 10% for C#. How do other people see this information for themselves if they don't have a careers profile?  Is this even possible without having a careers profile?
Answer: There is a technical difference between the rankings on Careers and those on SO top tags.  Currently Careers only ranks you against other people on Careers.  That being said, the distribution for most tags is reasonably close on Careers to what your top % would be for a tag on the whole of SO.
It is actually on our list to change our ranking to be that of SO, so I would suggest ignoring this difference for now.  For those curious why we made this distinction initially, it's because around a year ago, only the most engaged SO users were on Careers, and so our rankings showed everyone in the top 10%, 20% or 30% for just about every tag they had answers for.  Today we have many more profiles and we've been tracking the progress of these metrics with the intent to use the SO rankings once it makes sense.
Comment: Cool! I was just updating my answer to show the Careers rankings don't make much sense (top 10% in Django? With my measly 127 upvotes?).
Answer: That information is only available on careers profiles.
However, you can see the top 20 answerers in any tag. For C# for example, the following URL shows the current top 20, the top answerers for just the last 30 days, and the same information for questions:
<code>https://stackoverflow.com/tags/c%23/topusers
</code>
Here you see Jon is not only listed in that ranking, he holds the top slot.
Any tag page has this linked to the top users page, here is the C# page link:

If you yourself have answered questions with this tag, your score will be listed, but it may be placed at the bottom if you don't otherwise are ranked. That way you can at least compare your own score with the top users and see if you are close yet.
For the c# tag, which I don't follow myself, I managed to gain 1 point (probably a Python answer that was also tagged with C#), so I am listed at the bottom. The answer is older than 30 days, so I am not listed in the 30 day ranks at all:

This is of course not the same thing by far, but is also more accurate than the percentage reading given on Careers. On Careers I rank in the 10% for the django tag for example, but I don't rank on that tag's top 20 users page; in fact I have quite a ways to go before I'd ever get there. But for all people listed on Careers that have answers in that tag, I apparently rank in the top 10%. Golly. :-)
Answer: You can use Data Explorer to query for this information, like I mention in this answer. Now that the data is updated fairly regularly (weekly), this should give you a reasonable accurate idea of where you stand in a given tag.
Note however that the percentile on Careers is calculated differently, as it's based on your position among users who also have Careers accounts. As such, the Data Explorer figures may be more relevant anyway as they look at the entire user population.


Tips to build faster in Minecraft creative

Question: I'm working on building an Ancient Egyptian temple in Minecraft for social studies and it is due this friday. I still have a lot of work to do on it and I am a slow builder in creative mode. Can I please have some tips to build faster so I dont go down in my grade?
Comment: It isn't clear what you need to do. Are you having an issue with planning your build or just that the speed of placing the blocks is too slow?
Comment: speed of placing blocks @PausePause
Answer:
WorldEdit - a mod providing copy-paste features, tiled fill, and a bunch more. It can really speed up massive builds with a lot of similar parts.

the /fill and /clone commands. Much more cumbersome to use but available in vanilla.

Debug stick - allows to change states of blocks, e.g. rotate them, set in states that aren't normally available, say, stand-alone corner stair block.

Tweakeroo, another mod with support for fancy placement modes - e.g. easily placing blocks with special facing rules (pistons, logs etc) in desired orientation without need to move around to place them from the correct side; also adjacent or otherwise aligned - placing block against an edge (diagonally adjacent) of other block, or with one block of gap.

Litematica - allows "pasting" saved structures into the world, similarly to WorldEdit but while it's more cumbersome, it's also more "visual" - you get a preview of the operation. Also allows easy migration of big structures between worlds.

"Pick block" - vanilla functionality: middle-click while looking at a block (from roughly breaking distance) to put a copy of it in your hand, so you don't need to switch between blocks manually, you can "pick" from the build.

Saved Hotbars. Another vanilla function. Set up your hotbar with a "family" of blocks you use together and press C + [number] (1 to 9). Now if you press X + [the same number], no matter what you had in your hotbar, it's replaced by the same set. Preparing a couple hotbars with "palettes" for particular purposes (also saving the debug stick so you don't need to /give it to yourself whenever you need it), really speeds up the work.
Comment: `/fill` and `/clone` are also really useful if you don't want to use world edit, specially considering `/fill` can do hollow filling, replacing specific blocks and what not
Comment: @SF. is there a  way to get world edit in a world i already created?
Comment: @RoxyKatGaming Yes, install Fabric, worldedit, pick the Fabric profile from launcher and it will work just fine with all your old worlds. And they'll work in vanilla just fine, it doesn't generate anything vanilla can't handle.


Windows search bar loading for no reason

Question: My windows is acting weird.
Whenever I open explorer to whichever folder, the windows search green bar at the top starts up.
Sometimes this prevents me from seeing the stack structure on the left and when this happens I can't even click on my drives because they're non existent.
I have to manually open my c or d drive if I want to get anything done.
I tried restarting explorer and my computer several times to no avail.
Does anyone know what's going on?
Attached is a screenshot of the problem but it's finicky when trying to reproduce the full issue with no drives and folders so this is what I got.
Comment: Do you perhaps have a disc inserted in the optical drive?
Answer: First do this commands on an Elevated command  prompt:
<code>sfc /scannow
dism /online /cleanup-image /restoreHealth
netsh winsock reset
</code>
Another solution that worked for me is to open Explorer by default in quick access, instead of This PC. Open Control Panel > Appearance and Personalization > File Explorer Options and set "Open file explorer to" to Quick Access from the drop-down list.
Answer: You will also see this sort of creeping green bar if you have added
a network location to Explorer.
For example, you might have once connected to a NAS drive
(network Attached Storage)  or a shared folder on another computer
and used it to copy files or whatever.
Windows will remember the network location and the next time you
use Explorer, it will try to reconnect.
This is fine if the other end is available, but if it is not then Explorer will
keep retrying until it eventually gives up and realize that it is just not available.
All the time it is trying to connect, it will show that annoying green bar
creeping across the top.
There are two possible solutions:

Ensure that any shared resources like NAS drives, USB drives, other PCs with
shared folders and so on, are all up and running when you use your PC.

Disconnect from the shared resource: Select This PC on the left and then
click Computer at the top to view the toolbar.
Click the down arrow under "Map network drive" and select "Disconnect network drive".


Meta Analysis for one proportion

Question: I have data summarizing proportion of events from 5 different papers. The proportions are in %'s. For example, in paper number 1, there was a report of 2000 people and a proportion of 10%. I want a general proportion and CI's. I tried using a generalized linear mixed model with PROC GLIMMIX in SAS, but for some reason, the probability estimate I got was equal to the average of all proportions, and not the weighted average as I would expect. I used a binomial link function, and declared: model proportion/n =  / solution cl; and random intercept / subject=paper; I took the model's estimate, and calculated the probability using (1)/(1+e^-estimate). As I mentioned, I got the exact mean of the percentages, and not the weighted mean like my logic say I should have got. I can easily calculate the weighted mean by hand, but I need a CI. Can you help me do it, preferably with SAS, if not, then with R ?
Comment: You must look for some indication of spread in each of your papers, be it Confidence Intervals, Standard Deviations or Mean Square Errors. What do you find?
Comment: I do not have this information, all I have is the proportion of each paper. I used an older method of Tukey and Freeman (arcsin transformation), which gave two results: fixed effect and random effect. The fixed effect was equal to the weighted mean while the random effect was not. I don't understand why.
Answer: The method of Freeman and Tukey would be appropriate here or indeed using another transformation like the logit. These are widely available in R packages of which there is a list on the CRAN Task View.
The reason why the fixed effect model differed from the random effects is that the random effects using weights which incorporate a component depending on between study variability leading to weights which are more similar than the fixed effects ones.
Disclaimer: I maintain the Task View mentioned above.

Meta Analysis for one proportion


Are EM radiation and EM waves the same thing?

Question:
Are EM radiation and EM waves the same thing? I have seen this topics treated separately in many books. It is still not clear to me whether EM radiation and EM waves are synonymous. Is there any difference?
Another question: When one says that EM waves are solutions of Maxwell equations on vacuum does this mean that there is no charge at all in any point of space?
Comment: Related question [What is the relation between electromagnetic wave and photon?](http://physics.stackexchange.com/q/90646/)
Answer: EM waves are a special case of electromagnetic radiation, where typically the source is periodic, or near enough that there is a carrier wave, as with radio and television.
Maxwell's equations support a "sourceless" electromagnetic wave, as if it has existed forever.
Also see Why do we think of light as a wave?
Let's consider two cases of electromagnetic radiation which is not obviously wave-like:
For a brief, non-periodic motion you get pulses, which can be decomposed into a myriad of wavelengths. For example, ultrafast optical pulses, with a duration of a few femtoseconds, can be modeled as the travelling interference packet of a very large number of independent waves, all travelling in the same direction. If you separate such a pulse with a diffraction grating -- you actually obtain such a spectrum! See chirped pulsed amplification, especially the diagrams.
For a more spread-out source, consider that thermal radiation typically originates from a large collection of randomly oriented and stimulated miniature antennas, which can be statistically described. Due to the random phase factors it will not show much (if any) coherence, but can be separated into a thermal spectrum with an appropriate diffraction grating. Due to the random nature of the thermal generation, you should not expect to see any large scale wave behavior.
With an IR viewer one can still see an image; this is due to contrast variations, corresponding, for example, to variations in temperature of the object.
Comment: Thank you for the answer. So is there EM radiation which is not a EM wave? What would be the main difference this radiation originated from a non periodic source would have compared to EM wave?
Answer: Whether waves == radiation is somewhat a question of semantics, and thus a bit subjective, however...
In general wave equations support radiation, but not all solutions to a wave equation are radiative. Evanescent solutions are also called waves ("evanescent waves"), yet typically not considered to be radiation since they do not propagate in three dimensions.
A notable example of electromagnetic evanescent waves is surface plasmons. The near fields around an oscillating dipole are are also waves in some sense, but they are not propagating.
Comment: Thanks Nanite! Does the following analogy make sense? Radiation is for EM wave as perturbations in the sea are for a sinusoidal wave. For instance some perturbation in the fluid could be composed by many natural modes or maybe they could be non linear and the final result would be a dispersion. While a sinusoidal wave would keep propagating.
Answer: 1.
I think, the difference of "EM waves" and "EM radiation" is the different focus while it both deals with electromagnetic fields.
The first thing I associate with "EM waves" are the things I associate with waves: wavelength, frequency, diffraction, interference, phase & group velocity. The differential equations of waves and for EM waves in general the Maxwell equations. It is pretty much the classic electromagnetic theory.
In contrast "EM radiation" deals mostly with the characteristics of energy transfer: Thermal and Black-body radiation, flux (watt, lumen), intensity, brightness, reflectivity. In case of ionic radiation it looks at the (harmful) exchange of radiation with biological tissue.
2.
Different charge distributions cause electric and magnetic fields which will need energy to build up and which may have different characteristics.
It may be a static electric field. It may be a static magnetic field.
I can create EM waves with any phase velocity I like (Hint: c is not a barrier, see anomalous dispersion). The thing is that there is no connection between the wavefront, But important is: I always need energy to sustain this specific field.
The Maxwell equations now show us if and only if the speed of a resulting wave is exactly c, then no further energy is needed to propagate the wave: The wave becomes self-sustaining.
Answer: UPDATED ANSWER :
The short answer, appropriate to A level or below, is that there is no difference.  The term "EM waves" usually means "EM radiation" - ie visible light, IR, UV, X-rays, gamma rays, radio waves, etc.
The situation is a little more complicated because the same EM radiation can behave as waves or as particles (photons) in different situations.  It also occurs as long trains of a single frequency or short pulses of a spread of frequencies, but that doesn't make them different phenomena.
However, all periodic solutions to Maxwell's Equations are also called "EM waves".  EM radiation is only one particular solution - the only solution which is self-sustaining and travels through a vacuum.  All other solutions require the presence of charges, conductors or dielectric media or "wave-guides" of some kind.
Your 2nd question is not clear.  That EM waves (ie EM radiation) are solutions of Maxwell's equations in a vacuum means that they can propagate through empty space for an unlimited distance and do not require any medium composed of polarisable material.  However, they do require electric charges in order to be emitted (radiated) or absorbed.
Comment: Are you able to measure the wave characteristics of an thermic source - for example of an electric bulb powered from an DC current?
Comment: @HolgerFiedler : I am sorry, I do not understand how your question relates to my answer.
Comment: Read Petter Diehrs answer. A radio wave is a modulated EM radiation and really has the characteristics of a wave. A thermic source doesn't have such characteristics. The only waves are the photons of any EM radiation with their oscillating electric and magnetic field components.
Comment: @HolgerFiedler : It seems to me that you and Peter are complicating the issue.  I think the OP is asking if there is any difference in essence, not in form.
Comment: @HolgerFiedler Sure, the coherence length of a thermic source is quite small, but you can observe *all* wave characteristics: diffraction and interference. What exactly do you think happens with EM radiation from a thermic sources if it passes a slit ? Something different than light ?
Comment: @ThorstenS. Since single photon and single electron deflection on edges are performed it is obvious that the particles in the radiation are responsible for the intensity distribution behind edges. So we can talk about the wave characteristics of a photon with its oscillating electric and magnetic field components.


Proton attached to N or O in HNMR spectroscopy

Question: I was wondering why a hydrogen attached to a nitrogen or oxygen is not able to couple with p+ on adjacent carbon atoms and hence why it always appeats as a singlet in HNMR spectroscopy?
Answer: It depends on the condition of your experiment if a coupling of a proton of an amino or hydroxyl group with a proton attached to the $\alpha{}$-carbon is observable, or not.  As pointed out by the indicator set by @Mithoron, intermolecular exchange processes need to be taken into account.

If your alcohol (or amine) to be analyzed is very pure, and the deuterated solvent you deploy is both very pure, and dry, and free of acids or bases catalysing proton exchange, than you may observe $^3J$-couplings you expect to see.  For example a freshly opened sample of deuterated DMSO (used as solvent) may contribute to this observation.  See the peak data of the 1H NMR spectrum of ethyl alcohol in DMSO here.
If you aim to analyze an alcohol, not well dried, analyzed in deuterated chloroform or methanol that was frequently exposed to ambient (humid) air, then indeed instead of a triplet of an hydroxyl group  ($\ce{-OH}$)  attached to a methylene group ($\ce{-CH2-{}}$) all what may be spot is a broad singlet signal.  The same reference, 90 MHz 1H NMR in deutero chloroform provides one example.  (Note the chemical displacement of the hydroxyl protons altered, too.)


What is the minimum length required for an answer and how is this enforced?

Question: Is there a minimum length required for an answer to meet the minimum requirements for answers on this site? Two of my short answers were recently suggested to be lengthened since their length fit within the 600 character limit of a comment (see here and here). This seems like an arbitrary threshold, since we are specifically discouraged from answering questions in the comments. If there is a minimum length requirement, what is it, and if not, why is this being policed? Interactions like these discourage interaction with this site.
Answer: I apologize that this is very likely not the answer that you were hoping to get. Please understand though, that if there's parts of this answer with which you disagree, I'm willing to discuss them with you in as much detail as you desire in the Meta chat room.
Preamble about the tone
Your comment here, combined with the next one and this Meta question, has the following undertone:

"Despite being new to this site (and network!), or having more than one account but needing to make a new one recently, I know better than you, how this site should work."

To have a constructive conversation about this, I would really appreciate a bit more modesty and perhaps some respect for the people that devoted thousands of hours towards building the site. It is rare, but once in a while we get a new user who simply thinks that they know better than everyone else, and engages in rollback wars or ranting on Meta, and if perhaps you can try to put yourself in my shoes, I believe that you will be able to see that such "challenging" of the status quo would ideally be done more respectfully.
Answer to the question
You have asked a legitimate question though, so it deserves an answer!

"Is there a minimum length required for an answer to meet the minimum requirements for answers on this site?"

On all SE sites, when an answer is flagged for being VLQ (very low quality), the peer reviewers are given a message that says "This answer has been flagged due to its length and/or content".
Therefore, answers that are too short are quite often considered VLQ.
In terms of a precise number of characters for a minimum length. For a long time I have been meaning to have a minimum length of 600 characters (the allowed amount for a comment) implemented so that users cannot click the "send" button until their answer is at least as long as a comment can be, but I haven't gotten around to that yet because I first wanted to ask the CMs for other things such as getting a shortened mirror URL (matter.stackexchange.com) and implementing other things that have been proposed in the past, but rejected by CMs who were recently fired or laid off by the Stack Exchange upper management.
This 600 character limit has been implemented "in practice" in that answers that fit in a comment are either deleted, or converted to a comment, or converted to a Community Wiki, or extended in length by the original author after a suggestion was made in a comment. I can provide a very good example of the last of these outcomes when I'm next on a desktop (I'm currently typing on a tablet). There's also a very good example of the first of these outcomes (deletion of the answer) in the thread to which you provided a link in your question here (that answer that was deleted, was also written by one of the highest-rep users on this site, so the "policing" isn't only done to new users). This paragraph also hopefully answers the second question in your question's title: "how is it enforced?
Are we being unreasonable?
Based on everything that you wrote (especially in the comments on your answers), I have the impression that you think it's unreasonable to expect those answers to be any longer. Of the 4000+ answers on MMSE though, it will be extremely rare to find answers that are as short as the three that you wrote yesterday.
We have about 4000 questions on this site, and it would be too coincidental if three of the only ones that "necessitate" the answers to be shorter than 600 characters, happen to all be the three ones that you were able to answer within one day (and the only three ones that you answered in that day).
Short answers are VLQ, but why?
I mentioned earlier that VLQ answers can be VLQ due to their length being too short, but why? I think this is a fair question, and if it is asked on Meta, I'll write an answer to it.
Policing short answers is discouraging

"Interactions like these discourage interaction with this site."

I agree. This discouragement might be a good thing though. This relates to the question "Why are short answers considered VLQ?", which might be a fair Meta question to ask if someone disagrees or can't see why they are considered VLQ.
Also, a related question that I long ago asked at QCSE.Meta, that I have been meaning to also ask here at MMSE.Meta, is "What are the goals of this site?". As the principal founder of this community, I have ideas in mind for the answer to this, but I'd also like to hear what others think the goals would ideally be. If one of the goals is to get as many people participating as possible regardless of the quality of the answers, then answers ought to be far more welcomed regardless of their length. Some users who have posted VLQ content have been driven away by the community already though, and this has almost always not been by me (I have never downvoted a single post, and when people disagree with me I tend to write long explanations like this one, to provide the reason for my views)!
What I may have done wrong
My method of communicating to people that their answers are considered too short, probably needs to change. Copying and pasting people's answers in a comment to show that the answer was so short that it fits in a comment, isn't necessary and might just piss off the authors of the answer, leading to fortified opinions against setting a minimum number of characters for answers. However, it also sends a strong signal that the answer's length is sub-standard, which is why I have been doing it. Ideally there would be a quicker/easier way to provide in comments on main-site answers, links to faq Meta posts; and perhaps doing that would be better than what I have been doing when I see overly short answers.
Comment: While writing [this answer](https://mattermodeling.stackexchange.com/a/12458/5) just now, I originally felt that I had sufficiently answered the question with just one line, but I managed to reach 700+ characters, and by doing so, I made the answer more informative and helpful to the user, without making it too verbose (700 is very manageable for almost every type of reader).


g++ : How can I get keystate on linux

Question: I Want to get keystate for some key like shift. If I press "a" with shift to write "A" then by g++ program on linux how can I ensure that shift is also pressed while I press key "a".
Thanks in advance.
Answer: See the answer for this question: What is Equivalent to getch() & getche() in Linux?
It will give you the correct keycodes, i.e. 'a' if you press 'a' with shift depressed, 'A' if you press it with shift pressed, etc. Getting the state of the shift key alone is a different matter though, I'm not sure if there's an easy way to do that.

g++ : How can I get keystate on linux


Filter with Price Not shown in Navigation Layer

Question: I have a simple product under the same category with different prices and my store is multilingual (i use the same currency euro), I just configured the price as manual and I checked that price is filterable with results but it's not shown to filter
Answer:
Check (Use in Layered Navigation) property in your price attribute. Stores->Attributes->Product->Price->Storefront properties

Reindex and clean the cache.
If it doesn't work follow this : Mageplaza Price Filter configuration


After Upgrading from 12.04.to 12.10 will i have to install my drivers again?

Question: I want to upgrade from 12.04 to 12.10 but will i have to install the broadcom drivers and some softwares that i installed from backtrack repository??
Answer: Please, don't mix repositories! BackTrack is no longer supported by their creators which recommends the use of Kali. And no, normally you don't have to reinstall your drivers, unless you built them from source with options not included in the default installations, which is this case.


Pixelated light cone near source with Eevee

Question: In my renders with Eevee, I'm getting pixelation of the light cone near the light source. What settings do I need to adjust to fix this please?
Answer: OK, I've discovered the answer.
In render setting for Eevee, go to 'Volumetrics' settings and change the 'tile size' to a smaller pixel size. You can also adjust the 'sample rate' settings underneath the 'tile size' settings.
This does seem to increase render time considerably however.
Another simpler option is to widen the angle of you light cone. I don't know why, but this too seems to eliminate the problem. Perhaps someone else can expand on why.


BBM-like iPhone app?

Question: I keep hearing all this hoopla about BBM (Blackberry Messenger) and I want in on the fun. Is there anything similar to BBM out there for the iPhone? I heard WhatsApp was something like it, but just wondering if there were any others.
Comment: Whats app, is cross platform, and will work on Windows, Android and BB.
Answer: WhatsApp and PingChat are the major games in town.  I've also heard a bit about Cnectd
Nothing has really sold me yet, as I'm looking for proper delivery and read notification a la BBM.
Now if someone could figure out how to cross the impossible chasm to somehow connect into the BBM network, it would be a game changer.
Comment: I believe 2 or 3 of the ones I listed above ALSO have Blackberry versions - which is helpful if you can convince your BB friends to install and use it :)
Comment: Thanks! That's kinda what I thought (that there was nothing compatible with BBM). From what I've been reading, doesn't seem like anyone will be able to do so, but even if there was a universal app that all smartphones could use (even Blackberry users in place of/ in addition to BBM) would be cool.
Answer: Kik Messenger is relatively new and has the best feature from BBM (IMO);
Sent, Delivery, Read and typing status for messages
Unfortunately it was pulled from Blackberry's App World and actually blocked from pushing data on the Blackberry due to the fact that the founder was once an intern on the RIM BBM team.  RIM is actually in the process of suing Kik - which just goes to show you that they are onto something.
Even without proper support on Blackberry, it's highly recommended for iPhone, and there is an Android version as well.
Answer: iMessage (Free)
iMessage, Apple's own messaging platform, can send and receive messages on iOS (5 or later on iPhone, iPad, and iPod touch), macOS and watchOS, as long as they are connected to either a Wi-Fi or cellular network (3G). Starting with iOS 10, Messages includes support for third party apps.
Answer: LiveProfile recently launched and is clearly GUNNING for BBM.  Even closer in look, feek and functionality than Kik.
Even the fonts are similar:

They say their Blackberry App will be out soon, but I'd be surprised if RIM doesn't give them a hard time.  iPhone and Android versions are currently available.

BBM-like iPhone app?


Debug Android mobile apps on an Android tablet

Question: I 'd like to know if is it possible to debug Android mobile apps on an Android tablet, but not in full screen - in real size in the middle of the screen as does iPad with iPhone application.
Answer: It depends on your layout settings of the screens inside the app. If the width & height properties of the parent layout(layout with the xmlns attribute) is set to 'match_parent'/fill_parent', the application will occupy the entire screen in the tablet also. If you don't want the full screen set it into 'wrap_content'.


Does the Necromancer minion get feats?

Question: I'm going to start a campaign using some of the variant rules in Uneartherd Arcana. One of my players wants to use the necromancer variant (Unearthed Arcana pg. 63), and I'm not sure if the skeleton minion gets feats normally or not.
Answer: Unless the text says otherwise, any creature with an Intelligence score gets feats. A skeleton, by default, is Int –. It therefore does not get feats.
Answer: This is a replacement for the familiar class ability of a wizard, and many of the qualities of the minion are similar to familiar abilities.  Though the text does not explicitly say so, I would be inclined to treat the minion's power progression similar to a familiar.  That would exclude gaining a feat per 3 HD.  However, given that all the other familiar abilities (besides HD increase, natural armor bonus, and Str/Dex increase) are not present with the minion, I would also consider allowing the normal feat progression based on HD.  There seems to be no rules text for or against it.  So, I would say it is up to you.
Edit:  In looking at the HD-progressed skeleton examples in the Monster Manual, the skeleton template specifically removes all feats from the base creature and grants only Improved Initiative.  So, it seems like "Improved Initiative and no other feats" is a special quality for skeletons in general (perhaps due to @KRyan's reason in his answer).  A skeletal minion would seem to follow suit.  So, I would say no feats based on HD, but add Improved Initiative as a bonus feat acquired via the skeleton template.
Comment: Mindless creatures receive no skill points and gain no feats other than racial bonus feats. Skeletons receive improved initiative as such a feat.

Does the Necromancer minion get feats?


Why did Palpatine choose Jango Fett's gene to create Clone Army?

Question: The plan of Palpatine for Clone Army was to make it accepted by The Galactic Republic. Couldn't a Bounty Hunter's gene make it difficult? Also, what was the benefits of using Jango Fett's gene? Why didn't he pick any random guy instead of Jango Fett?
Answer: The main reason for choosing Jango Fett's genes for this was because of his prowess in battle. Here is an excerpt from Wookieepedia:

Having captured Fett, the Bando Gora prepared to turn him into a mindless slave. It was here that Fett acquired many of his facial scars. Vosa herself came to demand of him the name of his employer, but Zam Wesell freed Fett before being injured by the insane Dark Jedi. After a long duel with Vosa, Jango Fett emerged victorious. As he prepared to finish her off, Vosa asked if he would choose to leave her dead or alive. Jango, looking at the ruined female nearing her death, lowered his weapons. Vosa murmured "He… is here." before being choked with the Force to her last breath.
To Fett's surprise, Tyranus was indeed there, and he was impressed. The bounty was a test to determine if the rumors of Fett's skills against Jedi were true. If so, his clones trained under his supervision would be very effective once Order 66, the order to eliminate all Jedi, was issued. While Fett had personally killed many Jedi on Galidraan, Tyranus considered his former apprentice a more challenging test. In addition to the bounty on Vosa, Tyranus offered Fett a tempting sum of money for an unusual task: Fett was to be a template for an army of clones. Fett agreed, and soon millions of clones were created in his likeness at the cloning facility on Kamino. Fett, however, remembered Rozatta's final wish and asked for one clone produced without genetic tampering, an apprentice and son that would become Jaster's legacy and revive the Mandalorians.

Not only was Fett supposed to provide his genetic makeup, he was to train the clones, which was his dual reason for being on Kamino.
Answer: Actually, Palpatine didn't personally select Jango Fett as the template for his clone army. Instead, it was Count Dooku who selected Fett, with Palpatine approving the choice afterwards.
To select the template for their clone army, Dooku selected some of the galaxy's most dangerous men - bounty hunters, mercenaries, convicts - and pit them against each other by placing a bounty on a Dark Jedi named Vosa. In addition, Dooku had once faced Fett in combat personally (at the Battle of Galidraan), where he witnessed Fett take out several Jedi single-handedly.
Lastly, Dooku found himself impressed with not only Fett's intelligence but also his resilience and devotion to duty. The combination proved to be an ideal match for what Dooku and Palpatine had planned with the clone army, and the deal was struck.


Are there any simple models for wildfire hazard mapping with ArcGIS ModelBuilder?

Question: I am interested in producing a simple fire hazard/severity map via ModelBuilder from commonly available datasets (e.g. DEM, NDVI, slope, aspect, land use/cover, etc).  Are there any resources or examples of simple models used to produce maps such as the example below?  Specifically, I am looking for a model that I can construct within about 10-15 minutes during a presentation to produce an interesting graphic.
Comment: For demonstration purposes, it will be difficult to construct a useful (and realistic) model in just 10-15 minutes.  Instead of trying to add every component into your model for the presentation, try creating a number of small sub-models which can contain the "details" of your analysis.  During your presentation, you can then 1) open each sub-model & show the processes going on, 2) drag the sub-model onto your "master" model, and 3) repeat steps 1 & 2 for each remaining sub-model.  This will be ensure you don't miss a step, and demonstrate the power of ModelBuilder.
Answer: There seems to be such a model described in detail here.  It uses the old ArcView 3 architecture but it looks like it could be adapted to ArcGIS 10.1.  Constructing it in 10-15 minutes would be a challenge so you may want to drop out some of its "less critical" input datasets.
Comment: Thanks, great link.  This link helped a great deal for putting together a simple fire risk model for a presentation.
Answer: I would use the example for a suitability-analysis shown in the ArcGIS Spatial Analyst extension tutorial and modify it using your criteria for wildfire risk. What you describe is in the end a "suitability analysis" for wildfires.
You can find the Tutorial here:
The model should be constructable in 10-15 minutes if you have your criteria preprocessed. The most important tools are "Reclassify" and "Weighted Overlay".
Answer: I think it's depend on your purpos. first you should choose your method.for example u can use ahp,topsis,... methods if you want to rate your parameters or use fuzzy method or weithed overlay to overlay the layers and then create model using model builder and python scripting.


icinga2 mysql connection issue

Question: I followed all the install wizards When setting up icinga2, I have the following error:
SQLSTATE[HY000] [2002] Can't connect to local MySQL server through socket '/var/run/mysqld/mysqld.sock' (13)

I tried using the mysql command line utility, and I got the same response. To fix this, I symlinked the socket such that ls -alF shows the following:
lrwxrwxrwx 1 mysql mysql 25 Jun  2 10:23 /var/run/mysqld/mysqld.sock -> /var/lib/mysql/mysql.sock=

and ls -alF /var/lib/mysql/mysql.sock returns
srwxrwxrwx 1 mysql mysql 0 Jun  2 10:39 /var/lib/mysql/mysql.sock=

Now the mysql command line works without complaint, but I continue to receive "Can't connect" errors from the icinga2 web interface. I cannot find anywhere in the logs that shows any errors. I've checked the following log files:
ido2db.debug (does some stuff and then cleans up child processes)
apache2/error.log (nothing)
apache2/access.log (shows requests coming through from web interface)
icinga2.err (nothing)
icinga2/startup.log (looks pretty standard)

There do not appear to be any logs that are specific to the icinga2 web interface (there's no /var/log/icingaweb2, and there's no web log in /var/log/icinga2)
I do not want to change the mycnf file because I have many other services relying on the current location of the mysql socket.
How do I solve this problem? I can't seem to find a config that I can modify for icinga2 to point it at a different socket. Can I set up mysql to have 2 sockets?
If I change the my.cnf file to set the socket in the correct location, everything works.
Answer: The directory /var/lib/mysql is usually only readable my the users mysql and of course root.
So any other user, like nagios, icinga or Apache's system user won't be able to access the socket.
Comment: But it works when I change the location of the socket in my.cnf, and that socket is also owned by mysql?
Comment: What OS is that?
Comment: I'm running this on Ubuntu 14.04

icinga2 mysql connection issue


Having trouble finding cloud cover data

Question: I'm working on a project for a GIS course, I chose to find the best locations for the placement of an observatory. To accomplish this I planned to use cloud cover (or percentage of clear nights), proximity to existing roads (probably a TIGER file), Some measure of light pollution (I have found a few good rasters for this), I was also considering adding elevation to this project too, but I think I can find a good DEM to use. I am having trouble locating any data for cloud cover. I am thoroughly inexperienced with meteorological data and some of the filetypes I've found I have no idea what to do with, I found one other question on here about it but none of the answers really got me anywhere. If anyone can point me in the right direction that would be great.
Comment: Would I be correct, with your mention of TIGER data, that you are looking to locate this observatory in the U.S.?
Answer: Part of the problem might be with your search term. 'Cloud Cover' is typically discussed in the context of sat imagery and specifically a percentage of blocked image. You're looking for cloud (or clear sky) frequency.
This is often a factor in studies to locate solar power facilities. Going down that route might skew your data since they're primarily concerned with clear days and you're looking for nights. But one example I noted was http://www.nrel.gov/gis/data_solar.html
Another potential source, depending on the time window and resolution you need is http://www.cgiar-csi.org/data/uea-cru-ts-v3-10-01-historic-climate-database which tracks nine climate variables globally from 1901 to 2006 at 0.5 degree resolution.

Having trouble finding cloud cover data


How to best organize a directory structure of a dictionary?

Question: I need to create an English language dictionary. I plan to store dictionary entries inside text files (one file per entry) and store those files in file system. I'm looking the best way to organize the directory structure.
My first guess is the following:
<code>/a
  apple.txt
/b
  book.txt
/c
  can.txt
...
</code>
But, since there are about 250000 words in English language, this structure is not good (since there will be about 9000 words in a directory).
So, what is the best way to organize files in directories? And will I be able to store the files in a GIT repository (won't it be too slow)?
Answer: Because git will create one node for each file, I don't think directory structure will influence the git accessing speed, the speed depends on the number of all your files. You should focus the design of directory structure based on the algorithm you will take to look up the dictionary.
Answer: Yes, you can store it in a GIT repository, and it should not affect the speed, although what I think you mean is whether you could push such a repository to a git host (you can). Plenty of huge repositories larger than dictionaries are hosted on GitHub and GitLab.
As for the structure, I don't recommend putting each word in a separate file. It would be easier to put a lot of words into one file, using some format, separating each word with a delimiter. That way, your main dictionary program could scan a few files, rather than having to repeatedly open and close files. It would also make your repository far easier to navigate.


Millikan oil drop experiment

Question: I had a question about the Millikan Oil drop experiment. I did the experiment for my physics class where we had to determine the voltage that would make the droplet stationary. We did this ten times, so I have ten different voltages. The mass, gravity, and distance remains the same it is only the voltage that is changing. The part I am struggling with is, I must determine my own fundamental charge from this experiment and compare it to the accepted value of 1.6x10^-19. How do I determine my own fundamental charge when I am given 10 different voltages? I believe that I am supposed to use the q=mgd/V equation but I am not fully sure.
My mass is: 1.57x10^-15 C
My distance: 0.1 m
Gravity: 9.81 m/s^2
My voltages: 400, 457, 384, 369, 400, 355, 369, 436, 384, and 369.
Comment: Have you tried calculating q for each of your values of V?
Comment: Yes, I calculated all of the q values for V.
Comment: Were those q values mostly near $1.6\times10^{-19}$ C, $2 \times 1.6\times10^{-19} $ C, ... ? Or perhaps were they near $some value$, $2 \times some value$, ...?
Comment: They were not. They were actually around values like, 3.37x10^-18 C all the way to 4.17x10^-18 C. I calculated the differences between all the charges and then I got values around 1.6x10^-19 C to 4.9x10^-19 C.
Comment: The smallest non-zero difference between your calculations should be due to only 1 electron.
Comment: Ya for my first differences amongst the 10 charges, I got 2 values that were 1.6x10^-19. But is there a way I can calculate my own fundamental charge using the q=mgd/v equation?
Answer: It appears that your measurements may have been very imprecise. However, given your data, the best approach is to find a value for e such that the RMS differences between the charges $q_i$ you found and the nearest values of $n_i e$ to the $q_i$ is minimized.  That is, minimize the square root of the sum of the squares of $(n_i e -q_i)^2$ by fiddling with the value of $e$.  Choose $n_i$ for each $q_i$ so that $n_i e$ is as close as possible to $q_i$.  Easy to do in a spreadsheet.

Millikan oil drop experiment


What are the prerequisites for instruction pipelining to work?

Question: When can it be applied? When can it not be used? I get the general idea but not what it takes to make it work.
Answer: The main use case for pipelining is when your latency is large, but actual work is small. You hide the latency by scheduling many operations such that the latencies overlap but the actual work does not.
It can't be used if the latencies are not independent. An example is calling people from a phone just to say "yes". The actual work is very small, the latency is very large, however your phone can only call one person at a time so you can't actually apply pipelining.
If you had multiple phones however you could start dialing the next person while the previous phone is still ringing.


Source Server support on VMs with VMWare Lab Manager and TFS?

Question: My company is interested in better integrating our investment in VMWare with our TFS deployment. Currently the company is running TFS2005 SP1, VS2010, and we have a sizeable SAN that we would like to use in environment reproduction similar to what is offered in TFS2010 Lab Management.
Of the features offered by TFS2005, we are currently leveraging only TF Version Control--work items and build automation are handled by separate systems. However, we would like to use the TFS-integrated Symbol/Source server in order to accurately debug the different versions of our product, and that's where we're running into difficulty.
The VMs deployed in VMWare are not joined to the corporate domain, and this means that we run into difficulty when attemping to grab source code information via Source Server and the "tf.exe view" command.

If devenv is run on the VM, it can't authenticate a domain account, and tf.exe view fails when grabbing source info.
If devenv is run on the developer desktop and debugging is done with remote debugger, the vm's local user account fails to access the share exposed by Symbol Server and can't load symbols to begin with, much less retrieve source.

Has anyone done this before?
Comment: Did the answer below end up helping you get this problem solved?  Thanks!
Answer: Yes - You can still do this.  If you are using Windows 7 (and I believe Windows Vista) you can always add the domain credentials to the "Credentials Manager" in the Control Panel.  This will help it authenticate for the TFS URL whenever it needs to talk to TFS.
BTW, I have a blog post discussing the Symbol Server and Source Server features of TFS 2010 available here:  http://bit.ly/SymbolServerTFS


Way to tell if WCF service is called via HTTP or HTTPS?

Question: Let's say you've got a WCF service that is accessible via HTTP and HTTPS, but you want only certain methods to be available with HTTPS-- how can I check if the current request is HTTPS? Since HttpContext is empty, you can't simply check HttpContext.Current.Request.IsSecureConnection -- any other ideas? Thanks in advance.
Answer: Consider that WCF applications can also be hosted as a Windows service, with no ASP.NET at all, in which case there is no such thing as "secure" vs. "insecure."  That is one reason why WCF does not attempt to make this information available.
One option would be to run the WCF service in ASP.NET Compatibility Mode, where you do have access to the HttpContext.Current instance.
My choice, however, would simply be to create a different, SSL-only service for the secure operations.  I really think you'd want to do this anyway, so the contract is explicit; otherwise you're left doing runtime checks and clients may have no idea that the methods they're trying to use aren't allowed.
"Best practice" in a web service is to make these types of restrictions as explicit as possible, and having a separate service available only over SSL is by far the clearest means of describing your service's restrictions.
Answer: ( Building on comment from @Aaronaught within answer by Matt Ellen... )
It looks like
OperationContext.Current.RequestContext.RequestMessage.Headers.To.Scheme

contains "http" or "https" among others (msdn).
Answer: HTTPS is served over a different port to HTTP. Assuming you know the ports, perhaps checking that would suffice.
Comment: @Aaronaught: `OperationContext.Current.RequestContext.RequestMessage.Headers.To` should return the uri that the request is sent to.
Comment: Right, so how do you find the port that's in use?  Meta-problem.
Answer: How about:
var iwrc = WebOperationContext.Current.IncomingRequest;
var isHttps = iwrc.UriTemplateMatch.BaseUri.Scheme.Equals("https", StringComparison.InvariantCultureIgnoreCase);

This is very easy, does not rely on port numbers and works just fine in a self-host WCF server (with no IIS in site sight).


Transforming flat file to XML using XSLT-like technology

Question: I'm designing a system which is receiving data from a number of partners in the form of CSV files. The files may differ in the number and ordering of columns. For the most part, I will want to choose a subset of the columns, maybe reorder them, and hand them off to a parser. I would obviously prefer to be able to transform the incoming data into some canonical format so as to make the parser as simple as possible.
Ideally, I would like to be able to generate a transformation for each incoming data format using some graphical tool and store the transformation as a document in a database or on disk. Upon receival of data, I would apply the correct transformation (never mind how I determine the correct transformation) to get an XML document in a canonical format. If the incoming files had contained XML I would just have created an XSLT document for each format and been on my way.
I've used BizTalk's Flat File XSLT Extensions (or whatever they are called) for something similar in the past, but I don't want the hassle of BizTalk (and I can't afford it either) on this project.
Does anyone know if there are alternative technologies and/or XSLT extensions which would enable me to achieve my goal in an elegant way?
I'm developing my app in C# on .NET 3.5 SP1 (thus would prefer technologies supported by .NET).
Answer: XSLT provides new features that make it easier to parse non-XML files.
Andrew Welch posted an XSLT 2.0 example that converts CSV into XML
Answer: I think you need something like this (sorry, not supported by .NET but code is very simple)
http://csv2xml.sourceforge.net
Answer: IIRC someone has created a "LINQ to CSV" library that might be a starting point to create the intermediate XML (in memory) as input into the transform.
Found it here.
Answer: I have found 2 potential solutions when looking into a similar problem space.
Progress Software has a set of tools and API (.Net), which when used in conjuction with .conv (flat to XML converter) files created in their Stylus Studio tool allows for transformation of any pre-defined flat file format into XML at run time.  More info here: http://www.datadirect.com/developer/data-integration/tutorials/converter-sample-code/index.ssp
In addition there is an XML format called XFLAT which allows for the description of flat files in a variety of formats, delimited, fixed width etc...  There is a java program which will convert flat files, where you've provied the XFLAT description into XML so that you can continue with a standard XML to XML XSLT transformation.  More details can be found here: http://www.unidex.com/overview.htm
I have never actually used either of these tools, but found them when researching a similar problem.
Answer: You might try LINQ to CSV. There is one offering from Microsoft's Eric White and another from Matt Perdeck. Others are out there...
Answer: Check out this article on implementing an XmlReader that processes non-XML input.  It's not a terrifically difficult task, and once you've got it working you don't need to use an XSLT-like technology, you can just use XSLT.
Answer: this will parse the output from the linux ip route list command. It's just what I had laying around.
you must wrap the output from the comman in an element called 'output' and the style sheet will take it from there. The real key here is the tokenize command in the xpath 2.0 spec. I don't know how you could do this before that. Also this doesn't make a single root element, as that was not what I needed it for. In your case, instead spliting on space, Id spli on a ','
<?xml version="1.0" encoding="UTF-8"?>

<xsl:output method="xml" indent="yes" />

<xsl:template match="@*|node()">
    <xsl:copy>
        <xsl:apply-templates select="@*|node()" />
    </xsl:copy>
</xsl:template>

<xsl:template match="//output">

    <xsl:variable name="line" select="tokenize(.,'\n')"/>
    <xsl:for-each select="$line">

        <xsl:variable name="split" select="tokenize(.,' +')"/>
        <xsl:if test="count($split) > 1">
            <xsl:element name="route">
                <xsl:for-each select="$split">
                    <xsl:choose>
                        <xsl:when test="position() = 1">
                            <xsl:attribute name="address" select="."/>
                        </xsl:when>
                        <xsl:otherwise>
                            <xsl:variable name="index" select="position()"/>
                            <xsl:variable name="fieldName" select="."/>
                            <xsl:if test="$fieldName and position() mod 2 = 0">
                                <xsl:attribute name="{$fieldName}" select="$split[$index + 1]"/>
                            </xsl:if>
                        </xsl:otherwise>
                    </xsl:choose>
                </xsl:for-each>
            </xsl:element>
        </xsl:if>
    </xsl:for-each>
</xsl:template>

Answer: You can also take a look at altova's MapForce
Comment: Altova MapForce wants to generate code to go from a flat file to an XML file. It doesn't do it purely with XSLT.


Clustering: measure of dispersion based on distances

Question: I am having a set of strings, they have been alligned and I have a matrix of pairwise distances. Now the objects have to be clustered yet I do not know the number of clusters beforehand. I would like to calculate some parameters that would help me decide - starting with intra-cluster variance and gap statistics.
The point is that I just have the distance matrix, not the coordinates themselves. What kind of analyses could I performed based on that?
Answer: You can for example use the Ward's method implemented in scikit-learn or fastcluster. It will produce a dendrogram, and you scan spot at which level you should cut the dendrogram by looking at the variance decrease (sort of elbow method), cf. this post on se.


What does "OMG ponies!" mean?

Question: What does this mean and what is the origin of this phrase?
Answer: I could be mistaken, but I believe this exact phrase originated on Slashdot, in an April Fools' prank on April 1, 2006.
From the Wikipedia page on Slashdot:

In observance of April Fools' Day (April 1) in 2006, Slashdot temporarily changed its signature teal color theme to a warm palette of bubblegum pink and changed its masthead from the usual, "News for Nerds" motto to, "OMG!!! Ponies!!!" Editors joked that this was done to increase female readership.

The exact Slashdot article said this:

Our marketing department has done extensive research over the last 3 quarters and discovered that our audience is strangely disproportionately skewed towards males. Like, 98.3% males to be precise. To correct this oversight, we have decided to subtly tweak Slashdot's design and content to widen our appeal to these less active demographics. Don't worry! We'll still continue to serve our core audience, but we hope you'll work with us as we try to find a balance that will work for all.

There was a stream of articles on the site that all followed this theme of writing, using lots of caps and texting phrases like LOL, OMG, lots of exclamation points, and getting excited about things like My Little Pony, glitter, the O.C., and other things young girls would be interested in.
Here is the Slashdot site logo from that day:

The meaning of the joke is that this is how young girls write things.  So, this phrase is used as a way to jokingly react like a 12-year old girl would.
Comment: That was an annoying day to read Slashdot.
Answer: According to Urban Dictionary:

an involuntary exclamation when
confronted by extreme awesomeness or
cuteness
"I logged on and and saw the
pics of your new l33t rig and thought
"omg ponies!"

l33t (from 1337) => leet => elite (gamespeak)
Comment: Gamers jokingly picked up "leet-speak" from the script-kiddies from the early 90's.  For the most part, gamers use this language ironically.  for steamrolling English, you can't get much worse than Facebook and Twitter posts from wannabe gangstas on both sides of the pond.
Comment: You have to love how so many "gamers" have thoroughly steamrolled the English language. It's no wonder why so many people out there can't spell properly. {sigh}
Comment: @Will - [It turns out that there's no relationship between the use of intentional nonstandard spellings and ability to spell correctly](https://phys.org/news/2009-09-chatspeak-impact-children-ability.html).
Answer: While Slashdot April Fools' prank popularized the term, those pranksters probably took it from a Cute Overload post from a day before. The site Cute Overload was fantastically popular in its day.
This is as close as I have found to an authoritative definition of the phrase:

[13-year-old voice] LOL!!!!!!!! BBQ!!!! OMG, Sooooo kewl!!! CUTEST PONIE EVAR!!!
AAAAAAAAAAAAAAAAAAAAAH! dies. dies again. ^_^  KBYE! [/13]
Comment: I'm not entirely convinced since the C.O. post actually references the Slashdot site (presumably because they had already posted their "OMG Ponies!").

What does "OMG ponies!" mean?


How do criminals change IMEI numbers

Question: I read that mobile network providers can block IMEI numbers from most networks but I also read that criminals can change these IMEI numbers in order to regain access to a network. How is this done and what can I do to protect myself from it?
Comment: "_what can I do to protect myself from it?_" I may be missing something, but what do you feel you need protecting from? In what way are you "_in danger_" from a criminal who somehow manages to regain access to the mobile network (especially given they could just get a new phone)?
Answer:
criminals can change these IMEI numbers in order to regain access to a
  network.

Not only criminals, changing IMEI is easy even without root access, there are plethora of apps that can do just that.

How is this done and what can I do to protect myself from it?

For most devices, IMEI is stored in EEPROM, simply raising a voltage from normal working one will allow you to change whatever is stored on it.
You mostly can't do anything to protect only IMEI. Hardware limitations. However, you can for example encrypt your phone internal storage, set a startup code, enable device locator and so on. This will make it harder for criminal who stole your device to actually profit from it.
Unfortunately, not all phone models support that (startup encryption)
Comment: Yeah i know about startup encryption i have seen some Samsung S models that support it ( S8/S9 are two that i know of ) And i read something about it being stored in a EFS on the device and if you root the device and then somehow corrupt the file and restore from a backup of another device then you can change the IMEI how true and possible is this?
Comment: One more question let's say a criminal takes my phone and doesn't use it for anything but just copies my IEMI number to a new device will this render my device useless on that network since there will be two copies or what? Sorry for not making very much sense just new to possible cell phone scams
Comment: And what do you mean by raising the voltage from normal working how does that change the IMEI? And does a criminal have to use a legitimate IMEI number or can they just generate a random one? These apps you mention how do they change the number?
Comment: All right - corrupting and restoring device from a backup - not sure about it, probably related to some models and firmware versions.
Copy IMEI and use it on another device - The one that was registered first to a number will have a prevalence.
EEPROM memory to be able to overwrite you need to fluctuate voltage (raise it) to wipe and overwrite. Just google EEPROM, your laptop's bios works the same for example.
Comment: Refer to this: https://en.wikipedia.org/wiki/International_Mobile_Equipment_Identity

For IMEI generation procedure: https://www.gsma.com/newsroom/wp-content/uploads//TS.06-v16.0.pdf
Comment: From what i read the process is you corrupt the EFS on a rooted phone and then you make a backup of the IMEI of another phone and afterwards you copy that backup to your computer and then to the other phone afterwards using a EFS restore tool you can restore the EFS to the target phone making the IMEI register as another
Comment: Also what about a IMEI that is on a phone that isn't in use on any cellular networks anymore could a attacker use that for a stolen phone?
Comment: Generally, rooting a phone is against security guidelines.
If IMEI is spoofed that is not tied to a phone number, the one that will be tied will have prevalence. There are however ways to circumvent if you will become the owner of a phone with a legitimate IMEI that was spoofed by another. You will need to talk to a vendor and gsm provider.

How do criminals change IMEI numbers