Version of the Relativistic Train Paradox

I am having trouble resolving a version of the well known relativistic train paradox. I would prefer a qualitative explanation although any help is appreciated.  Imagine a train and a tunnel which, when they are at rest relative to each other, are of the same length.  The tunnel has a left opening (entrance) and a right opening (exit). Imagine that the tunnel has a door on its right opening (exit) which is initially closed.   Assume that there are matching sensors on the tunnel's entrance and on the back of the train, so that when the back of the train enters the tunnel a signal is sent to open the front door so that the train can pass safely through the tunnel.  Now let the train travel from left to right at a speed fast enough, so that the train shrinks to a quarter of the legnth of the tunnel in the tunnel’s frame.   In the tunnel's frame of reference, the tunnel is 4 times as long as the train. The back of the train enters the tunnel (sending a signal), the front door opens, and the train passes through safely.  But in the train's frame of reference, the train is 4 times as long as the tunnel. So a signal cannot be sent to open the initially closed door before the front of the train reaches it. In the train's frame of reference there is a terrible accident and all of the passengers die.  How can these two scenarios be reconciled? which one is true? I think the main difference between this version of the paradox and the "classic" one is that here the opening of the door depends on the back of the train entering the tunnel.


Will store eggs turn into a chick if i leave it out in the warmth?

I want a baby chick and i was wondering if i could leave a store egg our in the summer's warmth/ a warm place and let it turn into a baby chick.. does it really work???


Does the Fullmetal Alchemist manga deviate significantly from either of the anime series?

I've seen both the 2003 anime and Brotherhood, and I know Brotherhood is more faithful to the manga than the 2003 anime. So I'm wondering if it's worth the effort to get all the Fullmetal Alchemist manga, or is Brotherhood so faithful to the manga that it's just the manga in anime form (i.e. the manga has no major plot twists that deviate from the anime)?


What is the potential variation inside solid conducting sphere?

The information on the internet is highly unreliable, these websites say that potential remains constant inside conducting solid sphere:     These sites say potential varies as a function of distance:     which one is it?


Extending the search context in the admin list post screen

I have created a custom post type and have attached some custom fields to it. Now I would like to the search that authors can perform on the custom post list screen (in the admin backend) to also be performed on the meta fields and not only look in the title and content as usual.  Where can I hook in and what code I have to use?  Example image   Stefano


I have an Ubuntu 12.04 production server with 500 GB (nearly 15 GB used) HDD. I want to duplicate whole HDD including it's partitions structure, data to another HDD with 400 GB size so that changing HDD will not affect working system.  Which tool is the best solution for this task?


Is posting links to your own blog/site valid?

Is it acceptable to post links to your own blog/site as part of an answer or comment if you have a covered a particular topic in detail and it will assist or answer the question?


Sign up: Double opt-in still best practice? What about mobile?

Everybody knows the normal registration process:    Fill in sign up form Wait for email Click confirmation link in email Done (signed in & confirmation by email)   IMO this process works because people are used to it but it isn't very elegant because it breaks the user's flow. The same process on in a mobile app would look something like this:   Fill in sign up form Wait for email, switch to email app Click confirmation link in email Browser opens and shows confirmation page Switch back to app Type in sign on information Done   This is just painful (even more so if the email address used for the sign up isn't the one that is used on the mobile's email client).  I see two main alternatives but both have some issues:   Don't require a confirmation by email, just sign in the user immediately. Main problem: We can't be sure if the email address is correct (other than syntax). Don't require immediate confirmation: Let the user confirm his email address in the next 7 days or so and sign him in immediately. Main problem: Still can't handle wrong email addresses   Are there any other alternatives or more elegant ways to handle registrations?


Package was missing for WEEKS, got refunded, then showed up just now....will the company take back the refund?

As it says in the title.  Will the company be able to electronically take back the refund even without speaking to me?  I'm peed off about the prospect of having to give THEM money for an item that went missing for SEVENTEEN days with NO tracking update, NO useful knowledge from SEVERAL customer service reps with weird names written without capital letters, after TEN days of NO update which smells like a missing item especially during a virus shutdown (maybe the foreign package didn't pass customs, maybe it never even left the airport, what the freak) and no response from the USPS for a week after submitting a report, and NO communication at ALL from the company issuing ANY kind of reassurance nor apology before AND after taking it upon myself to contact THEM. So to basically have to repay them makes me SICK. On top of THAT, folks, they USED MY contact information...to sign me up....for spam websites....I know it was them because it happened right after a live chat, which went badly by the way.   So what BOTHERS and kind of SCARES me is the idea that they can auto-charge me, or take back the refund, because it just sounds like hacking, fraud, theft to dip into my account essentially to do that. Is it even possible for a clothing company or any company to electronically reclaim a refund/recharge me!? Also, including that question, is there ANY responsibility (NOT moral obligation, but legal responsibility) that I could possibly have to actually return a refund for a 17 day late package and horrible customer service? This is their screw up, the package happened to come as a surprise to me and I'm sure to them as well as they said three different and all incorrect delivery dates.


Need help writing a command in minecraft

I'm trying to set up a custom sword shop on my server with command blocks, and i'm stuck trying to spawn a custom model, data item already renamed/colored.  You can do this: /give @p minecraft:diamond_sword{CustomModelData:1000001}  And you can do this: /give @p minecraft:diamond_sword{display:{Name:'{"text":"Ancient Sword","italic":false,"bold":true,"color":"light_purple"}'}}  Is there a way to combine the two, or chain 2 command blocks to get the same result? I'm not sure if I explained it well enough, but I would really appreciate some help on this. Thank you.


can you guys help me with understanding the basics about what is Exposure value and how to use that for better photography?


Can someone provide me rules to detect following attack :   hping3 -S -p 80 --flood --rand-source [target]   I'm having problem with rules since packet comes from random source.  My current rules is :   alert tcp !$HOME_NET any -> $HOME_NET 80 (flags: S; msg:"Possible TCP DoS"; flow: stateless; threshold: type both, track by_src, count 70, seconds 10; sid:10001;rev:1;)   this rules only can detect from one source ip only.


So I found this public:     ListElem(string s);          string     getData(void) const;     ListElem*  getNext(void) const;     ListElem*  getPrev()     const;  Btw this is a snippet of a list in a header file written in cpp Can someone tell me whats that "(void)" for? Where is the difference between methodName() and methodName(void)?


Is there an English word for a feeling of impending doom or dread?

Is there a word for a feeling of impending doom or dread?


When should I use `scipy.stats.wilcoxon` instead of `scipy.stats.ranksums`?

I've been using  but then I realized that there is   They sound like they are pretty much the same.  I always hear wilcoxons referred to as wilcoxon rank sums.  In SciPy how are they different and how can I know which one to use?  My data is rarely normally distributed which why I use these non-parametric tests instead of t-tests.


When I try installing anything I get error E: Malformed entry 1 in list file /etc/apt/sources.list.d/atom.list /etc/apt/sources.list.d/atom.list: deb https://packagecloud.io/AtomEditor /atom/any/ any main


How to merge audio and video file in ffmpeg

I want to merge an audio file (.wav or .au format) with a video file (.mp4 format).  Please suggest me how to achieve this. I want to merge these file to new .mp4 video file. An ffmpeg command would be very welcome.


Why don't all objects bounce like rubber balls?

Some things don't bounce like rubber balls do.  For example, books don't bounce much when dropped.  Why is it that some things bounce while others don't?


Say if I define a power series over some arbitrary field $F$ as   $$a = \sum^{ \infty }_{i = 0} a_{i} X^{i} $$  Then can I say:  $$ab = \sum^{ \infty }_{i = 0} \sum^{ \infty }_{j = 0} a_{i} b_{j} X^{i + j} $$


How can i delete Ubuntu from the computer?

I want to clear my computer from everything but i have no clue how I will do this with Ubuntu Plz help me before i will throw my computer throgh the window. With other words i don't want to have anything from Ubuntu left in my computer.


How can I make a seamless particle animation cycle?

Let's say I wanted to make a rain/snow gif. Or bubbles under water. Can I make it so the last frame goes back to the first frame seamlessly? So that it's an animation cycle? Like a walk cycle but with emitter particles.


Is it a good practice to place C++ definitions in header files?

My personal style with C++ has always to put class declarations in an include file, and definitions in a .cpp file, very much like stipulated in . Admittedly, part of the reason I like this style probably has to do with all the years I spent coding Modula-2 and Ada, both of which have a similar scheme with specification files and body files. I have a coworker, much more knowledgeable in C++ than I, who is insisting that all C++ declarations should, where possible, include the definitions right there in the header file. He's not saying this is a valid alternate style, or even a slightly better style, but rather this is the new universally-accepted style that everyone is now using for C++. I'm not as limber as I used to be, so I'm not really anxious to scrabble up onto this bandwagon of his until I see a few more people up there with him. So how common is this idiom really? Just to give some structure to the answers: Is it now The Way™, very common, somewhat common, uncommon, or bug-out crazy?


Arguments for/against same birthday for siblings?

My son is born on October 1st three years ago. My wife is pregnant again and the calculated delivery date is October 22nd. Both children are boys, 3 years apart. We might end in a situation where the delivery is earlier, for reasons irrelevant to this question.   I believe that around their birthdays is the only time in the whole year that the actual date matters. It really does boil down to practical considerations around patience (gifts) and planning. I think that if there is, say, a week or more between the birthdays then it's easy to separate but if the difference is only a very few days then it gets complicated, and that's the situation I'd like to avoid.  I know from friends that having the same birthday makes events easier to plan, from the parents' perspective. It would also remove the unhappiness of a small child saying "why does he get presents today and I don't." Being a twin, and married to one, I know that there's nothing problematic in sharing a birthday as long as both get their fair share of attention.    What are practical arguments for, and against, choosing the same birthday for the second child? What considerations apply when the second child's birthday is only a very few days after the elder sibling's?


Why distance equals initial velocity times time Plus acceleration over two times time Squared?

i am a beginner in physics and I do not understand why is the d=vi(t)+(1/2)a(t^2).


How do I make a command to display a custom title page?

I followed the advice on the question  to try to make a custom command that displays a custom title page, but it is not working.   ./article.tex:17: You can't use `\spacefactor' in vertical mode.\@ ->\spacefactor                   \@m l.17 \makecustomtitle  Sorry, but I'm not programmed to handle this case; I'll just pretend that you didn't ask for it. If you're in the wrong mode, you might be able to return to the right one by typing `I}' or `I$' or `I\par'. ./article.tex:17: Missing $ inserted.<inserted text>                 $ l.17 \makecustomtitle  I've inserted a begin-math/end-math symbol since I think you left one out. Proceed, with fingers crossed. ./example.tex:17: You can't use `\spacefactor' in math mode.\@ ->\spacefactor                   \@m l.17 \makecustomtitle  Sorry, but I'm not programmed to handle this case; I'll just pretend that you didn't ask for it. If you're in the wrong mode, you might be able to return to the right one by typing `I}' or `I$' or `I\par'. ./example.tex:17: Missing $ inserted.<inserted text>                 $ l.17 \makecustomtitle  I've inserted a begin-math/end-math symbol since I think you left one out. Proceed, with fingers crossed.   What follows is the simplified code:  \documentclass[12pt]{article}  \newcommand{\makecustomtitle}{ \begin{titlepage}   \makeatletter    \@title by \@author    \makeatother \end{titlepage} }  \begin{document} \title{Please, be my title} \author{Andres Riofrio}  \makecustomtitle  Take on me.  \end{document}


At the end of , Captain Picard constructs a makeshift grave out of stones for Captain Kirk, who died helping Picard to stop Dr. Tolian Soran from destroying the Veridian system.    Was the burial only symbolic, or did Picard arrange for one of the starships picking up the Enterprise D crew from Veridian III to also retrieve Kirk's body?    Kirk was a Starfleet legend, and so a burial on Earth — with Starfleet brass and Federation dignitaries present — might have been in order.  Did this happen, or was Kirk's body simply left on Veridian III?  Since there is nothing further in the films or any of the television series about this (at least not that I can recall), any relevant information from the extended universe is welcome.


Is there a term for grammatical mistakes as a result of trying too hard?

Today, I learned the term  after writing that I was drinking a latté and then stopping to wonder why I was putting a diacritical mark on the "e".  This reminded me of other language mistakes that occur more frequently when people are actively trying to make fewer language mistakes, such as:   Every "----- and me" becomes "----- and I" Scattering "myself" throughout one's speech "whom" overuse   These mistakes tend to reveal "I'm talking to an authority figure" or "I'm talking to a group that I may not be qualified to be speaking to".  Is there a term for this phenomenon?


Give us an 'Edit & Close' button in the CV queue

When reviewing the Close Votes queue, the current button order often works nicely:     Leave OpenCloseEditSkip   But there's one problem: The function of the Edit button: Edits the post, then casts an (apparently binding(!)) Leave Open vote - that seems to kick the question out of the queue.  I don't very often use the Edit button, but most of the time I do use it is on posts with glaring problems.   What posts have glaring problems?  Low-quality ones. Often, it is these kinds of posts that need to be closed.   I would propose a checkbox above the Save Edits button - something like:       Cast a close vote   We could leave this box unchecked by default. When checked, the Save Edits button could also bring up a standard Close dialog - just like normal.


How to write $4-3i$ in the form $e^z$ with $z=x+yi$

I need to write $4-3i$ in the form of $e^z$ with $z=x+yi$. Important is that it shouldn't be like $z=\ln(\cdot)$. The exercise demands this. The problem is that I do not know how to evade the $\ln()$ form.   I've only managed to do this: $|4-3i|= 5$. $\text{Arg}(4-3i) = \tan^{-1}(-3/4)$.   So $e^x=5  \hspace{10mm} e^y = \tan^{-1}(-3/4)$   $x=\ln(5)      \hspace{10mm}            y=\ln(-3/4)$  Anyone have any idea how to evade the $\ln(\cdot)$?


Did the Dark Lord invent the Unforgivable curses?

Some people have suggested that the Dark Lord has invented the three Unforgivable curses.  I don't think this is true, but there are certainly some good arguments to suggest it.   None of the curses were mentioned in the prequel film Fantastic Beasts and Where to Find Them, which plays before the Dark Lord's time. The Dark Lord and his followers have used all three in the war significantly.  The killing curse even counts as the signature spell of the Dark Lord. People have pointed out that singling out these three spells as “Unforgivable” seems arbitrary and possibly politically motivated.  What better argument is there to ban certain spells can there be than to just choose the ones the most evil wizard ever have invented? The Dark Lord was powerful, talented, and smart, which are useful for inventing new spells. He has “travelled far and wide” after he graduated from Hogwarts (according to Chamber of Secrets chapter 18), and he has killed lots of  people.  I take this as meaning that he has gained a large amount of experience, which he could then possibly spend on researching spells.   Do we have proof that the Dark Lord has invented none of the three Unforgivable spells?


My xy data (which is in lat/long) wont show up with my other layers which are also shown in lat/long. They appear in two different places.. any advice?


I'm going to start a degree course in physics next year. So far in high school I covered some physics without calculus.  I know that I will start everything from the beginning at university, but I would like to prepare in some ways. Then the question is: what should I do? Should I revise what I studied? Should I go head?   Can you suggest (from your experience) what should I do before starting a physics degree course?  PS In case you recommend to study some material, can you suggest a book?


Combining shortcode and get_template_part

I manage a wordpress site and have created a template part that I usually paste below the content.

Featured store products
          <?php $catquery = new WP_Query( 'post_type=product&posts_per_page=4&orderby=rand' );         while($catquery->have_posts()) : $catquery->the_post();         ?>         <a href="<?php echo get_post_meta($post->ID,'PRODUCT-url', true);?>">

                         <?php the_post_thumbnail('small-thumbnail'); ?>

<?php the_title(); ?>

                   <?php endwhile; ?>
   Now I'm trying to put this IN BETWEEN the content, so I thought of using a shortcode  function get_products($atts) { get_template_part('block-products-inline'); } add_shortcode('products', 'get_products');   Now every time I post [products], I expect the products to go there. However when I try the code above, the products template_part goes all the way to the top of the page, right underneath the title and right before the actual content.  But when I edit the shortcode to simply return some text, then the text DOES appear in the middle of the content.  Does anyone understand what's going on? Because I don't..


How to vary the amount of a bump mapping effect on an object?

How do I vary the amount of a bump mapping effect on an object in cycles? I wanted to make a planet with a volcano using the both displacement method, but the effect displaced my volcano more than I wanted, as you can see.


NullPointerException while initializing method

I'm working on my Tower Defence game and right now I'm creating a wave of enemies. I wrote a method in class EnemyWave, that creates next wave. In my main class GameScreen, while starting new game I'm setting number of current wave to 0, which I need to use uptadeWave(), which creates new Wave in a game loop. I can't figure out why I get NullPointerException.    public void run() {       int frames = 0;      loadGame();     startGame("Level1");      while (running) {          repaint();         frames++;          waveUpdate();         enemyUpdate();          try {             Thread.sleep(2);         } catch (InterruptedException e) {             e.printStackTrace();         }     } }   Method which I have in run(), it gets errors in line with this.wave.waveNumber=0 (which should just set waveNumber to 0)  public void startGame(String level) {     createPlayer();      this.level = levelFile.getLevel(level);     this.level.findSpawnPoint();     this.map = this.level.map;      this.wave.waveNumber = 0;  }   Method which is creating wave in game loop    public void waveUpdate() {     if (waveID == 0) {         wave.nextWave();         waveID++;     }   }  Method which is beginning a next wave of my enemies.   public void nextWave() {     System.out.println("enemies are coming!!!");     this.waveNumber++;     this.enemiesThisRound = 0;     this.waveSpawning = true;  //  System.out.println("Wave " + this.waveNumber + "spawning!");     for (int i = 0; i < this.screen.enemyMap.length; i++) {         this.screen.enemyMap[i] = null;     } }   This is my first question in StackOverflow so if I should place here more, please just tell me. :)


How to terminate python program with given signal?

In C, I'd do something like  int main() {     return 42; }   and after executing the program, I can(in Linux) prompt echo $? to the console to get the desired 42 as the return signal from the last operation. How can I do that in python?  I tried just creating a file with a return 42 in it, but it says that it is not inside a function(obviously).


How to forward-declare/prototype a function in Python?

How do I prototype a method in a generic python program similar to C++?  //PROTOTYPE do python protoyping  writeHello() //GIVES ERROR AS IT WAS NOT DEFINED YET  def writeHello():     print "Hello"


My SQLite give me a null pointer. I am trying to write the points to the database, and to be able to read them from it. That is the complete table. There is nothing else in the table. I am getting the null pointer in the getPoints function, when I run the query. res comes out null.  Here is the code  public void onCreate(SQLiteDatabase db) {     // TODO Auto-generated method stub     db.execSQL(             "create table hour " +                     "(id integer primary key, number integer)");     db.execSQL(             "create table points " +                     "(id integer primary key, number integer)"     ); }  @Override public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {     // TODO Auto-generated method stub     db.execSQL("DROP TABLE IF EXISTS hour");     onCreate(db); } public boolean insertPoints (int points) {     SQLiteDatabase db = this.getWritableDatabase();     ContentValues contentValues = new ContentValues();     contentValues.put("number", points);     db.insert("points", null, contentValues);     return true; }  public int getPoints() {     SQLiteDatabase db = this.getReadableDatabase();     Cursor res =  db.rawQuery( "select number from points where id=1", null );     int i = res.getInt(1);     return i; }


What is the last version of Ubuntu 32-bit that downloadable for desktop with Intel processor

Hope you don't mind my question. I would like to know what is the last version of Ubuntu for desktop with Intel processor. I check , the last is Ubuntu 18.10 AMD64. Appreciated if someone can provide with a downloadable link.


Does turning airplane on and off constantly on my iPhone 6s ruin my hardware or ruin the iPhone in any way?


Why might the author have used "to be" instead of "is" in this sentence?

...thinking it to be in the green box when it is really in the yellow box.     The to be does seem to suggest that the green box does not actually contain it. Is to be, as used in the quotation, a subjunctive construction? If it is, then is that construction the most appropriate subjunctive construction; why or why not?  Thank you.


Stopped finding a specific wifi network, live works fine

I have Ubuntu 14.04.3 on a Dell Studio 1558 laptop with wi-fi adapter Broadcom Corporation BCM43224 802.11a/b/g/n (rev 01). My home modem/router is an EasyBox 803.  Suddenly my Ubuntu doesn't even show my network on the list. It normally shows and connects to other networks and my phone normally connects to this network.  Strange clue: I tried booting to a live Ubuntu 14.04.2 session on my laptop and it works as expected!


I'm just getting started with LaTeX, so likely missing something simple. I'm just looking for docs: how to get started, what commands do what, etc.  I found , but all it seems to provide is a link to a document describing differences between LaTeX 2 and 2e, neither of which I have any familiarity with.  Is there a good, online resource that acts as a kind of reference documentation for LaTeX?


How can I create a water material in Cycles?

I'm creating a scene with large amounts of water that will be readily visible, containing refraction and at various angles. The scene is an indoor long-course swimming pool, about 50 meters, all of which would be seen by a camera above 5 meters above the water's surface. This is being fluid-sim'd, but there are no quickly-moving objects or people, so any water movement is slower and in bulk. The "remove bubbles" option is enabled.  I've tried using a Mix Shader of Refraction BSDF and Reflection BSDF with the factor coming from a Fresnel node, but the results appear either too glossy or too transparent and overly colored. How can I make the water appear realistic? Changes to shaders (refraction to glass)? Or is tweaking colors sufficient?


Can I use the Wizardly Quill to make a free copy of my actual Awakened Spellbook?

I know the Order of Scribes can already make a copy of the Awakened Spellbook by making the ritual in another blank book, but that leaves the old Awakened Spellbook in blank. I want to have both Spellbooks in hand for pure Roleplay. Here's the rules for Wizardly Quill from Tasha's Cauldron of Everything:  As a bonus action, you can magically create a Tiny quill in your free hand. The magic quill has the following properties:  The quill doesn't require ink. When you write with it, it produces ink in a color of your choice on the writing surface.  The time you must spend to copy a spell into your spell book equals 2 minutes per spell level if you use the quill for the transcription.  You can erase anything you write with the quill if you wave the feather over the text as a bonus action, provided the text is within 5 feet of you. This quill disappears if you create another one or if you die    Here's the rules about replacing spellbooks from Player's Handbook:  Replacing the Book. You can copy a spell from your own spellbook into another book— for example, if you want to make a backup copy of your spellbook. This is just like copying a new spell into your spellbook, but faster and easier, since you understand your own notation and already know how to cast the spell. You need spend only 1 hour and 10 gp for each level of the copied spell.  If I'm not wrong, I don't need to spend nothing to test the spells I already know. Just need the right amount of ink and time to copy them. The Wizardly Quill is exactly made for this purpose of saving time and ink. That's my interpretation. Am I wrong?


states that "[human] infestation [by bacteria] begins at birth". This would suggest that unborn babies are free from any bacteria. However, if the mother catches a bacterial infection, her unborn baby risks catching it, too. This would seem to contradict the Scientific American article.  Presumably, when a human egg is fertilized by a sperm, the resulting cell may be free of any bacteria. At some point, bacteria begin to colonize the growing human body. Which bacteria are the earliest to colonize, and at what point in the development cycle does this occur?  In particular: does the health of the foetus depend on the presence of certain bacteria?


Why is my iPhone calendar stuck in the year 2562BE?

And how do I change it, to the current year, 2019?


I am working on showing a matrix completion problem is a SDP. Specifically, we want to show  \begin{array} \underset{minimize}_{ X\in \mathbb{R}^{m \times n}} & \sum_{(i,j) \in \Omega} ( X_{ij} - Z_{ij} )^2 + \lambda \| X \|_{tr} \end{array} is a SDP.   I know we can formulate $\|X\|_{tr}$ using its dual hence the above problem could be written as:  \begin{array} \underset{minimize}_{X\in\mathbb{R}^{m \times n},W_1\in\mathbb{S^{m}},W_2\in\mathbb{S^n}}  &\sum_{(i,j) \in \Omega} ( X_{ij} - Z_{ij} )^2 + \lambda(\text{tr}(W_1)+\text{tr}(W_2))\\ \text{subject to} & \begin{pmatrix} W_1 & \frac{1}{2} X\\ \frac{1}{2}X^{T}  W_2\\ \end{pmatrix}\succeq0  \end{array}  But I do not see how to show this is a SDP, either in usual form or canonical form.   Thanks.


My gas fireplace pilot will not light. It worked fine a few months ago until I shut if off.  My lighter has a knob which I turn towards pilot and hold pushed while I push the igniter button.  a few observations: 1.  I don't smell gas or hear anything when pushing in the knob to pilot 2.  Spark is visible  What can be causing this?  Thanks,


Take for example the case of a rod rotating about an axis passing through its centre of mass and perpendicular to it. It has a ring hung from one of its sides. The rotation of the rod causes the ring to move out wards and ultimately fall off the rod. Wrt ground the ring should experience a centripetal force inwards (right?) But still it moves outwards.Why? What is the force acting outwards wrt ground?


What are the minimum database privileges to run WP?

In my current installation, the DB user has been granted full privileges.     I am pretty sure that not all of them are required to run WP, but I am not sure which privileges are definitely needed. Any suggestions?


Can I use a power supply rated for my loads, or does it have to be rated for my amplifiers?

I am working on an audio amplifier system that uses as many as 10 amplifier modules that are rated at 400 watts each, so that is 4000 watts total. However the speakers that the amplifiers are driving are in most cases much lower wattage. For example, I might have 8 x 50 watt speakers, one 100 watt speaker, and one 250 watt set of speakers (I assume the wattage for the speakers is for the pair). So the total for the speakers is only about 750 watts. So, to power the amplifiers, can I use a 750 watt power supply, or do I have to use a 4000 watt power supply? If I can use the 750 watt supply, but there is a risk of a burnout if one of the speakers shorts out and the full 400 watts comes online from one or more of the amplifiers, is there some kind of protection circuit that can be used to avoid the burnout?


Seeking birth record for Jacob Schulthess from Wangen an der Aare in Switzerland?

I'm just getting started researching my husband's family who came from Wangen an der Aare, Bern Canton, Switzerland.   I'm looking for Jacob Schulthess birth record who was born 29 Jan 1892 in Wangen an der Aare.


Is it true that $ \lim_{x\to0}\frac{f'\left(x\right)-\frac{f\left(x\right)-f\left(0\right)}{x}}{x}=\frac{f''\left(0\right)}{2} $

Let $ f $ be a function such that $ f'' $ exists at $ x=0 $. Is it true that : $$ \lim_{x\to0}\frac{f'\left(x\right)-\frac{f\left(x\right)-f\left(0\right)}{x}}{x}=\frac{f''\left(0\right)}{2} ~~?$$ Im pretty sure that in order for this to be true, $ f'' $ should be continuous, which is not given. But I'm struggling to find a counterexample. I need to find a function that is twice differentiable, but $ f'' $ is not continuous (assuming I understood the situation). I'd appreciate some help. Thanks in advance.


Remove duplicate without modifying a list while iterating through the same list (python)

I have tried   def remove_extra(lst):     return print(sorted(set(lst), key = lst.index))  def remove_extra(lst):     b = []     for x in lst:         if x not in b:             b.append(x)     print(b)   All sort of removing duplicates codes however I don't know one that  give me True when result1 is lst1 where result1 = remove_extra(lst1)


If we have the following general regression:  $$ln(Y)=\beta_0+\beta_1 X_1$$  Then it can be interpreted as an increase of 1 unit in $X_1$ will increase $Y$ by $100 \times \beta_1\%$.  But what if the increase in $X_1$ is not 1 unit but say 0.5. Would it then be interpreted as "an increase in $X_1$ by 0.5 unit will increase $Y$ by $(100\beta_1 \times 0.5)%$?


phone number validation in Regular Expression

If I have lots of phone numbers like  123-456-7890 (111-111-1111 111)-111-1111 (123)-456-7890   I just want to match no.1 and no.4, my pattern can only match the no.4, and It seems that the if condition doesn't work.  (\()(\d+)(?(1)\)\-|\-)(\d+\-\d+)   All the solutions in regex websites can't recognize single bracket.


"mv" command-- file vanished into non-directory

I was attempting to utilize the mv command to move a file onto a remote server. I ended up executing the command...  mv sqlreport.php myuser@mywebsite.org   Unfortunately, this did not work. Worse, my file seems to have disappeared. A new file, myuser@mywebsite.org, has appeared, but it is not a directory (In that I cannot cd into it).  Any tips on where my file may have gone, and how to rescue it?


what is the time complexity to check if a dictionary has a key?

According to  given a dictionary D the operation  D[k] is constant. What is the complexity of k in D ? Is this still constant?


Is the space $(\mathbb Q\times\mathbb Q)\cup$$(\mathbb R- \mathbb Q\times \mathbb R-\mathbb Q)$ connected? I am really stuck at it. Any hints?


Displays tabs in Firefox 3.6 across multiple rows?

After upgrading to Firefox 3.6, I noticed that there no longer seems to be a way to have tabs all displayed in several rows when there are too many to fit in the window:    I find it very inconvenient to have to click on the down arrow at the far-right side to go through the list of open tabs.  The TabMixPlus add-on is incompatible with ReloadEvery 3.6.2, so that's not a good solution either.  Does someone know if it's possible to either configure FireFox 3.6 to go back to the previous way of displaying multiple tabs, or if there's an add-on that's compatible with ReloadEvery that would do the trick?    Edit: The solution if you need support for both multiple-row tabs + being able to reload one of the tabs automatically every so often, is to just use , which does both and is compatible with Firefox 3.6.


How do I share a private YouTube video with someone?

I have uploaded a YouTube video and marked it as private.  Now I want to share it with someone. I have tried to share it a few times, but they have not received any email notification.  What is the proper way of sharing the video?


I'm trying to find certain files with the name "stringx" and replace the name (but not the extension) with "stringy". So basically for stringx.txt and stingx.cs, I'd want stringy.txt and stringy.cs. I've attempted to test my rename command regex using following, but it returns no results:  rename -n 'stringx./s/\*$stringy./\/' stringx.*   I'm running csh under Centos. I can see that my regex is probably not correct, but I can't see any results to verify this. I can see that there are files that are named stringx. with the following:  find ./ -name 'stringx.*'


Ideal of polynomial ring is generated by a single element

Let $\mathbb{F}[x]$ be a polynomial ring over a field $\mathbb{F}$. Let $I \subset \mathbb{F}[x]$ be an ideal, that is,  $\forall s,t \in I: s-t \in I$ and $\forall r \in \mathbb{F}[x]: rs,sr \in I$.  Prove that $\exists c(x) \in \mathbb{F}[x] : I = \{c(x)g(x): g(x) \in \mathbb{F}[x]\}$.  Any hints as to which $c(x) \in \mathbb{F}[x]$ I should pick and how I should proceed? Also my notes highlighted this result as particularly important... why is this? Thanks!


How to open the group policy editor on windows 10

I am attempting to disable automatic reboots in windows 10, but looking at the answer , I find I fail at the first hurdle because I can't even open the group policy editor.  I then found , but none of those options seemed to work. For example of I type the word "group" into the windows search, I only see this:    If I actually type the two words "group policy" then I get "No results found for 'group policy'"  Looking on my HDD I can see that there are four instances of gpedit.msc in some very strangely named directories:


Find which dynamically created button has been clicked

I am trying to create something like stackoverflow.com tag cloud. I am able to display the tags but stuck on how to capture which tag element cancel button was clicked.  The cancel buttons are created dynamically using jquery on click of btnAdd.  $("#<%=btnAdd.ClientID%>").on('click',function(){   var tagText = $('#<%=txtTag.ClientID%>').val();   var btnCancel = '<button class="btn btn-default">X</button>';    var tagTextDiv ='
' + tagText + btnCancel +'
';    $("#divTagCloud").append(' ' + tagTextDiv); });   HTML is
    <asp:TextBox runat="server" />

    <asp:Button runat="server" id="btnAdd"/>

   I want to remove the tag i.e corresponding tagTextDiv on click of corresponding cancel button.   How to do this ?


If inverse $x^{- 1}$ of $x$ is $x$ how to prove $x = x^{- 1}$ is identity?

If $x = x^{- 1}$ how to prove $x$ is identity, namely $x = e$, in a group $G$? (Of course, in opposite direction this statement is obvious, because if $x = e$ then $e*e = e$ so $e = e^{- 1}.$)


Let $S$ be the equivalence relation defined on $\wp(\{1, 2, 3, 4\})$ defined by: $$XSY\text{ if and only if } |X|\equiv|Y|\;\mod 2$$ Write down the equivalence classes of S.  I understand that equivalence classes have relations where it is reflexive, symmetric and transitive but how are you supposed to write equivalence classes?


Long time learner, first time asker.  Let's pretend I have the variable "Sing" dimensioned as Single, and it's storing the value 5.6  Debug.print Sing displays 5.6, as expected.  When it is stored to the worksheet (Sheet1, A1), it saves "5.59999990463256"  The cell it's going to is formatted as "General".  It works completely fine when stored as a Double.  Any ideas what could be going on here?  I've looked through several posts about Single and decimals, but haven't yet seen anyone who's had this problem.  Sub testing()      Dim Doub As Double         Doub = 5.6     Dim Sing As Single         Sing = 5.6      Debug.Print Sing, Doub      Worksheets("Sheet1").Range("A1").Value = Sing #Pastes 5.59999990463256     Worksheets("Sheet1").Range("A2").Value = Doub #Pastes 5.6  End Sub


Commutative ring with finitely many minimal primes

$A$ be a commutative ring with $1$ with finitely many minimal primes $\{p_1,\ldots,p_n\}.$ Then how can I show that $S^{-1}A \cong A_{p_1} \times\cdots \times A_{p_n},$ where $S=A \setminus \bigcup_{i=1}^{n}p_{i}.$   So far I could prove that $\text{Spec}(S^{-1}A)=\text{Max}(S^{-1}A)=\{A_{p_1},\ldots,A_{p_n}\}$ and there exists a natural map $S^{-1}A \to A_{p_1} \times \cdots \times A_{p_n}$ , which exists by universal property of localization. How can I show that the natural map in injective as well as surjective?


So i have the following subspace  r − s − 2t − u  −r + 2s + 5t + 2u  s + 3t + u  3r + s + 5u  $$\begin{bmatrix}1 & -1 & -2 & -1 \\  -1 & 2 & 5 & 2 \\  0 & 1 & 3 & 1 \\  3 & 1 & 0 & 5 \\  \end{bmatrix}$$ These four equations are all put into square brackets. There are no zero's in the questions equal to the equations. This is a past exam question .   And i need to find the basis. I know that r,s,t,u are all scalars. I was thinking of decomposing these equations into variables and numbers, but i am not sure.  How would i find the basis ? Could somebody help me ? I was thinkig it might have something to do with the span.  YES i already asked the question. Please to not mark it as a duplicate.. I asked it again so more people can see it and maybe help me.


Difference in cd.. and cd .. (Change Directory)

cd.. and cd ...  Basically, they are doing the same. But, who and why thought of changing it with space or without space? Why is there space and why there isn't space between cd and two dots?  C:\Windows\System32>cd..   and  [bla/www/something/something]#cd ..   They are both the same. Why one has space, and another hasn't?  EDIT:  It's not duplicate of this question:.


Intersection of two principal ideals in an integral domain.

Could anyone give a specific example where the intersection of two principal ideals in an integral domain is not a principal ideal?


I want to output certain rows froms a spreadsheet to a different file, if they contain a number which is one higher than in the cell above

I have a large csv file looking a little like this:  SomeData,SomeData,1,SomeData   SomeData,SomeData,1,SomeData   SomeData,SomeData,2,SomeData   SomeData,SomeData,3,SomeData   SomeData,SomeData,1,SomeData   SomeData,SomeData,1,SomeData   SomeData,SomeData,1,SomeData   SomeData,SomeData,1,SomeData   SomeData,SomeData,2,SomeData   SomeData,SomeData,3,SomeData   SomeData,SomeData,4,SomeData   SomeData,SomeData,5,SomeData   SomeData,SomeData,1,SomeData   SomeData,SomeData,1,SomeData   SomeData,SomeData,1,SomeData   SomeData,SomeData,1,SomeData     I want to create a new csv file which only contains rows where the 3rd value is part of a set i.e. if the value in 3rd field of the line below is one higher, then I want both those lines to be included.  So, in the example above I only want rows 2-4 and 8-12 to be saved in a new file.  I'm struggling to work out how to tell grep to look for that pattern.  Any ideas?  Thanks


Sometimes I open more than seven or eight window. majority of this situation one of them is terminal. also you know that we need terminal during work. So I do not like to press ALt + Tab and after that skip to gain my own window. How many times I should do this!! for an important window like terminal which I need that repeatedly . So I need any key switch which bring terminal for me Not Alt + Ctrl + T, that one open new terminal. I need my own current terminal. Any way you suggest?


Why don't electrons in atoms radiate away their energy?

I am aware this question has been asked before, but I am looking for a more technical answer than those given to the other questions.  I am aware the question in the title is a problem in classical mechanics that quantum mechanics solves. But it doesn't seem immediately obvious at first blush how QM accomplishes this. For the simple hydrogen atom case, you model the electron as experiencing a static potential and also coupled to the surrounding radiation field.  From this $H$ there will be certain stationary states (for the joint electron-field system), but it doesn't seem obvious that these stationary states will involve nice atomic orbitals. You could imagine that the vast majority of the stationary states involve almost all the energy being stored in the field, and so any initial state with the electron orbiting the atom will not be an eigenstate and so tend to dissipate its energy to the field over time.  Is there a "deep" reason why this isn't the case, or is it just something that comes out of the mathematics?-


In the above diagram, assume that the level is solid and massless:  In the left setup, both mass are fixed on the level.  As we know, it is not a stable mechanical balance. For any tilt, the level will tilt more. In the right setup, both mass are hanged from a fixed location from the level. It is also the normal and old-fashioned setup for mechanical analytic balance.  As we know, it is a stable mechanical balance.  If one end is heavier than the other, the level will tilt to an angle and restore the balance.  But I can arrive at the above conclusion using mechanical analysis, e.g.:  If the two ends are not balanced, at what angle the level will stop. For the above to happen, what is the range of the ability to restore balance at any tilted angle.  Thank you.


Transit visa in Dubai (landing in XNB, leaving via DXB)

I am arriving in Dubai XNB at 6am from an Etihad flight. Then on 5pm, I am leaving Dubai on a Flydubai flight. Do I need a transit visa? (I'm Filipino so visa is always a constraint whenever we fly outside of Southeast Asia.)  I am asking because i have read conflicting accounts that I can ask for transit visa via Etihad since I am arriving from an Etihad flight.


How to sketch the following set $|z|=arg(z)$

I want to sketch the following set:  Set of all those complex numbers which satisfy the following equation $$|z|=arg(z)$$  Efforts:  We are looking at those points in plane whose distance from origin is equal to the angle they subtends with respect to x axis.   arg(z) is multivalued   Points like $(\pi/2,0)$ , $(2\pi,0)$, $(-\pi,0)$ belongs to the set. But what are other points.  How to plot this set.   Thanks for any help.


How to show this sequence is a delta sequence?

Consider the sequence $(\phi_n)_{n\in \mathbb{N}}$ of test-functions $\phi_n\in \mathcal{D}(\mathbb{R})$ defined by  $$\phi_n(x) = \dfrac{n}{\sqrt{\pi}}e^{-n^2x^2}.$$  I want to show that this is a delta sequence, in the sense that:  $$\lim_{n\to\infty}(\phi_n,\psi)=(\delta,\psi)=\psi(0), \quad \forall \psi\in \mathcal{D}(\mathbb{R}).$$  In that case we know that we have  $$(\phi_n,\psi)=\dfrac{n}{\sqrt{\pi}}\int_{-\infty}^{\infty}e^{-n^2x^2}\psi(x)dx.$$  The problem here is to compute this integral. The function $x\mapsto e^{-n^2x^2}\psi(x)$ has no singularities, hence contour integration wouldn't help. Integration by parts or substitution also doesn't seem to be of great help.  The major problem is that there is a function $\psi$ inside the integral about which we don't know really anything apart from the fact that it is $C^\infty$ and with compact support.  How can we compute this integral and in the end show that the sequence $(\phi_n)$ is a delta sequence?  Just to make clear, I'm here doing all of this in the context of the Riemann integral.


I overstayed my post study work Visa and was removed from the UK with a 2 year ban. How can this be overturned

I overstayed my Post study work Visa (having lived and worked in the UK legally for 8years)  because I had just been divorced and didn't have the wherewithal to immediately relocate to in my home country (Nigeira)  I was removed from the UK voluntarily and given a 2 year ban but when I applied for a visiting Visa 1.5 years later, I was told my ban is for 10 years.  How do I overturn this BAN?


Matching multiline strings doesm't work (regex, python)

I have a multiline string, like this:  tt = """ some text myvar=foo some more text """   Now what i want to do is to extract the value behind 'myvar=', in this case 'foo'.  I tried like this:  import re m = re.match('^myvar=(.*)$', tt, flags=re.MULTILINE) if m:     print(m.group(1))   But mis always None. It only works with single line strings, like:  tt = 'myvar=foo'   What am I missing? I am new to python, but not to regex.


Can I fly from Kolkata to Imphal without any documents?

I am 16 years old and I don't have any documents except my birth certificate and my students identity card is also expired. I am going to Kolkata to Imphal to apply for my adhar card. So how can I fly? Is there any way to fly?


Proving of Integral $\int_{0}^{\infty}\frac{e^{-bx}-e^{-ax}}{x}dx = \ln\left(\frac{a}{b}\right)$

Prove that      $$ \int_{0}^{\infty}\frac{e^{-bx}-e^{-ax}}{x}\,dx = \ln\left(\frac{a}{b}\right) $$   My Attempt:  Define the function $I(a,b)$ as  $$ I(a,b) = \int_{0}^{\infty}\frac{e^{-bx}-e^{-ax}}{x}\,dx $$  Differentiate both side with respect to $a$ to get  $$ \begin{align} \frac{dI(a,b)}{da} &= \int_{0}^{\infty}\frac{0-e^{-ax}(-x)}{x}\,dx\\ &= \int_{0}^{\infty}e^{-ax}\,dx\\ &= -\frac{1}{a}(0-1)\\ &= \frac{1}{a} \end{align} $$  How can I complete the proof from here?


I have created a Bootable Usb stick, I will create Ubuntu to C: but I have some saved documents like picture at d: If I install Ubuntu to c: , backup files from d: will erase ?


Rename files in selected folder in Linux

Command for rename file as IMG0001 to 4R0001 in folder  for f in *;do mv "$f" `echo "$f" | sed 's/IMG/4R/g' `; done   AND   I just want rename selected folder  /tmp/2014/1201 (rename files) /tmp/2014/1202 ....... /tmp/2014/1220 /tmp/2014/1224 (rename files) /tmp/2014/1227  .......   find not good for selected folder  awk for selected folder by renamelist.txt but miss match with for loop $value  Thanks


If it's too early to award a bounty, indicate so earlier

When I click on the Bounty icon to award it, I get asked Are you sure, and then I say I am sure, only to be told that it's too early.  , here's the sequence in pictures:  I see my bounty is still outstanding and that I have a great, spot-on, bounty-worthy answer:   I decide that  to award this bounty to a deserving user:   I see that I need to hold that thought for another two hours:    What's worse, is that I did the same thing 3 hours ago.  The only way I know that I can't award the bounty yet is to try (and fail) to award it.  (I guess I could notice on step #1 that the bounty doesn't end for another 6 days and infer that I still need to wait until it ticks over to 5 days.  But I wouldn't want to call that solution intuitive.)


Installing java 8 version in Ubuntu 14.04 and require jdk8. After extracting files from jdk 1.8.0 tar package from oracle java page and moving it to usr/lib/jvm, I am unable to find the oracle_jdk8 directory.


Are the groups $\mathbb{C}$ and $\mathbb{R}$ isomorphic?

Are the groups $\mathbb{C}$ and $\mathbb{R}$ isomorphic under addition?  And how could I prove this ?  What about $\mathbb{Q}$ and $\mathbb{Q}[i]$ ?


Assign a signature per contact in Gmail?

asks something similar, but it was related to Outlook and without an applicable answer.  Is there a way to to store a signature preference on a per contact basis? Or does anyone know of an extension to do something like this?  If you write to your mother, child, co-worker, vendor, or customer they all don't all expect the same thing. A custom field can be assigned to a contact, could that or another field be used somehow?   I just want to assign a specific signature to a user. Very similar to the way a custom ringtone can be assigned to a contact on a phone.


Computer not detecting headphones after upgrading from ubuntu 14.10 to ubuntu 15.04.

After upgrading my pc from ubuntu 14.10 to ubuntu 15.04 my pc can no longer detect headphones and can only play through the speakers. how can i fix this?


What is the difference between a variable referencing data and a variable containing data in C#?

I've been trying to understand passing by reference and passing by value and trying to understand it lead me to trying to understand reference data types. In all the explanations I've seen online they define a reference data type to be referencing data as opposed to containing data, and i'm wandering what is the difference?  What i think so far is that the variable doesn't contain data itself but it is referencing a method, but i don't feel like that is a satisfactory understanding. Hopefully someone could clear this up for me.


Ubuntu on Samsung Chromebook 2 boots to Chrome OS

I successfully installed Ubuntu 14.04 but it boots to OS (dev mode) and I don't know how to switch to Ubuntu. Ctrl+Alt+Shift forward/backward doesn't work. Please help!


Why is an assumption not discharged for the first implication introduction in natural deduction?

Why is it that an assumption need not be discharged for the first implication introduction in natural deduction? For example, $$\dfrac{\dfrac{[p]^1}{q\to p}{{\to}\mathrm I}}{p\to(q\to p)}{{\to}\mathrm I^1}$$ Why is it q need not be discharged like p?


Im trying to read 50 characters from web page source, begining from "Person" tag. Variable Index showing value 5443 which seems to be correct but i get nothing when I'm trying to print sub string import urllib.request  try:     with urllib.request.urlopen('SomeURL') as f:         full_str = f.read().decode('utf-8')         index = full_str.find('Person')         print(full_str[int(index):50]) except urllib.error.URLError as e:    print(e.reason)


Google Script Editor apply to all sheets except 1st, 2nd and 3rd sheet

Currently this code is only applied to the sheet called "Name" I wanted applied to all except for 3 sheets (Template,Summary and Count):   function EqualValue() {   var ss = SpreadsheetApp.getActiveSpreadsheet();   var sheet = ss.getSheetByName("Name");   var value = sheet.getRange("A5").getValue();   if(value >= "15") sendEmail(value)  };   function sendEmail(value){   var recipient="Tester@test.com";   var subject=" test subject " +value;   var body="The Value is "+value;   MailApp.sendEmail(recipient, subject, body); };   I am not sure how is best to do this.


Why Are Ethernet/RJ45 Sockets Magnetically Coupled?

As the title says really, why do ethernet sockets need to be mag-coupled? I have a basic understanding of electronics, but mostly, I can't figure out the right search terms to google this properly.


---- Minecraft Crash Report ---- // There are four lights!    Time: 5/7/16 9:13 AM Description: Initializing game    org.lwjgl.LWJGLException: Pixel format not accelerated     at org.lwjgl.opengl.WindowsPeerInfo.nChoosePixelFormat(Native Method)     at org.lwjgl.opengl.WindowsPeerInfo.choosePixelFormat(WindowsPeerInfo.java:52)     at org.lwjgl.opengl.WindowsDisplay.createWindow(WindowsDisplay.java:247)     at org.lwjgl.opengl.Display.createWindow(Display.java:306)     at org.lwjgl.opengl.Display.create(Display.java:848)     at org.lwjgl.opengl.Display.create(Display.java:757)     at org.lwjgl.opengl.Display.create(Display.java:739)     at bcc.ap(SourceFile:594)     at bcc.an(SourceFile:430)     at bcc.a(SourceFile:377)     at net.minecraft.client.main.Main.main(SourceFile:124)    A detailed walkthrough of the error, its code path and all known details is as follows:  -- Head -- Stacktrace:     at org.lwjgl.opengl.WindowsPeerInfo.nChoosePixelFormat(Native Method)     at org.lwjgl.opengl.WindowsPeerInfo.choosePixelFormat(WindowsPeerInfo.java:52)     at org.lwjgl.opengl.WindowsDisplay.createWindow(WindowsDisplay.java:247)     at org.lwjgl.opengl.Display.createWindow(Display.java:306)     at org.lwjgl.opengl.Display.create(Display.java:848)     at org.lwjgl.opengl.Display.create(Display.java:757)     at org.lwjgl.opengl.Display.create(Display.java:739)     at bcc.ap(SourceFile:594)     at bcc.an(SourceFile:430)    -- Initialization -- Details: Stacktrace:     at bcc.a(SourceFile:377)     at net.minecraft.client.main.Main.main(SourceFile:124)    -- System Details -- Details:     Minecraft Version: 1.9.2     Operating System: Windows 7 (x86) version 6.1     Java Version: 1.8.0_45, Oracle Corporation     Java VM Version: Java HotSpot(TM) Client VM (mixed mode), Oracle Corporation     Memory: 82295608 bytes (78 MB) / 148910080 bytes (142 MB) up to 523501568 bytes (499 MB)     JVM Flags: 6 total;   -XX:HeapDumpPath=MojangTricksIntelDriversForPerformance_javaw.exe_minecraft.exe.heapdump -Xmx512M -XX:+UseConcMarkSweepGC -XX:+CMSIncrementalMode   -XX:-UseAdaptiveSizePolicy -Xmn128M     IntCache: cache: 0, tcache: 0, allocated: 0, tallocated: 0     Launched Version: 1.9.2     LWJGL: 2.9.4     OpenGL: ~~ERROR~~ RuntimeException: No OpenGL context found in the current thread.     GL Caps:     Using VBOs: No     Is Modded: Probably not. Jar signature remains and client brand is untouched.     Type: Client (map_client.txt)     Resource Packs:     Current Language: ~~ERROR~~ NullPointerException: null     Profiler Position: N/A (disabled)     CPU:


Q: Volume involving spherical and polar coordinates

I'm trying to find the volume between the surfaces defined by the following equations: $$ x^2 + y^2 + z^2 = b^2 $$ $$ y^2 \tan^2 a = x^2 + z^2 $$ I need to find the volume using two different methods: the first one is by spherical coordinates and the second one by polar coordinates. The problem is I get two different results: Using spherical coordinates I found: $$ x = \rho \sin \phi \cos \theta \\ z = \rho \sin \phi \sin \theta \\ y = \rho \cos \phi $$ $$ V= \int_0^{2\pi}\int_0^{a}\int_0^{b}\rho^2\sin\phi \:d\rho d\phi d\theta = \frac{2\pi}{3}b^3(-\cos(a)+1) $$ and using polar: $$ x = r \cos \theta \\ z = r \sin \theta \\ y = y $$ $$ V = \int_0^{2\pi}\int_0^{b\sin a}\int_0^{\sqrt{b^2-r^2}}r \:dy dr d\theta = -\frac{2\pi}{3}b^3(\cos^3(a)-1) $$ So I know I have made a mistake at some point but I can't find it. If anyone can help I'd appreciate it. Thanks!


C++ inheritance constructor from base class

class SuperClass { public:      SuperClass(int foo)     {         // do something with foo     } };  class SubClass : public SuperClass { public:      SubClass(int foo, int bar)     : SuperClass(foo)         {         // do something with bar     } };   Does Subclass inherit the constructor of the superclass? What does its inherit and why i need to specify in sub class constructor the : SuperClass(foo)?


Short story about astronauts landing on a planet of shapeshifters

I'm trying to find an English-language short story I read in a collection about five to ten years ago (I don't have any idea of the original publication date).    Here's everything I remember:   The story is about human astronauts landing on an alien's planet, from the alien's point of view. Every organism on the alien planet is part of a single hive mind, and they can telepathically infect the humans (the aliens view this as beneficial, as any mind separated from the hive must be suffering), but choose not to once they realize that there's an entire planet of humans out there. The narrator alien is an organism that was designed by the hive to mimic a non-essential component on the spacecraft, so it can stow away when the humans return to Earth. The narrator alien is preparing to infect all of Earth as soon as the shuttle's door opens, but the component it replaced was the wire that opens the door, so it is fried instantly by the current.   Despite knowing all these elements of the story, I haven't had luck Googling it, because so many of these elements are very common sci-fi themes on their own, and I don't remember any unique names/terms.  I don't remember if I read this in a Sci-fi anthology book, or in a magazine (like 'Asimov').  Thanks in advance if anyone can help me track this one down, it's been bugging me for a long while.


At what point is the ~/.bashrc file created?

For instance, if I were to run the command adduser test, is the .bashrc created automatically upon creation of the home directory for the user test? If it's not created upon user creation, under what conditions is it created?  Also, if I add a .bashrc file to the home directory of a user, will it be overwritten by the OS?  Thanks in advance.


I do not understand what good it does them. A professor said it gives opportunity to read papers he would not read on his own. I am sure there is more to it but I do not see what they gain by participating in peer review process. It takes time, it is not paid and not even publicly acknowledged. Why do they do it?


Clone a database from SQL Server 2019 to 2017

I try to clone a database from an Sql Server on my local machine v15 (2019) to a server machine v14(2017). I did a .bak file and when I tried to import on the server side it says:  System.Data.SqlClient.SqlError: The database was backed up on a server running version 15.00.4083. That version is incompatible with this server, which is running version 14.00.2037. Either restore the database on a server that supports the backup, or use a backup that is compatible with this server. (Microsoft.SqlServer.SmoExtended)  Is there a "compatibility" backup mode on the 14-15 Sql Server versions? local (on docker, Linux):  Microsoft SQL Server 2019 (RTM-CU8-GDR) (KB4583459) - 15.0.4083.2 (X64)   Nov  2 2020 18:35:09   Copyright (C) 2019 Microsoft Corporation  Developer Edition (64-bit) on Linux (Ubuntu 18.04.5 LTS)   distant (on Windows Server)  Microsoft SQL Server 2017 (RTM-GDR) (KB4583456) - 14.0.2037.2 (X64) Nov  2 2020 19:19:59   Copyright (C) 2017 Microsoft Corporation Standard Edition (64-bit) on Windows Server 2019 Standard 10.0  (Build 17763: ) (Hypervisor)


Is there any continous function $f:R-R$ such that $f(x)\in Q$ for all $x\in R/Q$ and $f(x) \in R/Q$ for all $x \in Q$?All the functions i considered following given conditions are not continous.How do i know for sure if there are any or not?


I want to use launchd to update my MacPorts tree periodically (i.e. port selfupdate.  I have created /Library/LaunchDaemons/org.macports.selfupdate.plist:   $ ls -l /Library/LaunchDaemons/org.macports.selfupdate.plist -rw-r--r--  1 root  wheel  669  8 Nov 12:49 /Library/LaunchDaemons/org.macports.selfupdate.plist   It has the following contents:   <?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd"> <plist version="1.0"> <dict> <key>Label</key> <string>org.macports.selfupdate</string> <key>ProgramArguments</key> <array>     <string>/opt/local/bin/port</string>     <string>selfupdate</string> </array> <key>StandardOutPath</key> <string>/var/log/org.macports.selfupdate.log</string> <key>StandardErrorPath</key> <string>/var/log/org.macports.selfupdate.err</string> <key>RunAtLoad</key> <true/> <key>StartInterval</key> <integer>604800</integer><!-- 1 week --> </dict> </plist>   I've loaded it and verified that it's loaded:  $ launchctl list | grep macports -   78  org.macports.selfupdate   But it doesn't look like it actually run.    $ port info wireshark Warning: port definitions are more than two weeks old, consider updating them by running 'port selfupdate'. wireshark @1.12.8_3 (net) ...   What am I missing?


How can I redirect output from stdout into vim?

I would like to view the output of echo in vim, and save to a file after having a look at it. I have tried echo $PATH | vim, but I get the following error:  Vim: Warning: Input is not from a terminal Vim: Error reading input, exiting...  Vim: Finished.   What can I do?


$\mathbb{A}^{2}$ not isomorphic to affine space minus the origin

Why is the affine space $\mathbb{A}^{2}$ not isomorphic to $\mathbb{A}^{2}$ minus the origin?


How can I prevent my "trivial" answer from being converted to a comment?

Now that the , I've been spending some time browsing older retag requests to see which ones can now be completed.  , I tried posting the following answer:     Now that the ,   I see no reason why this tag can't be fixed.   I was then notified "Trivial answer converted to comment".  In this scenario, I think this is a significant enough development that it should be posted as an answer, and not as a comment.  How can I prevent my answer from being auto-converted to a comment?


Login problem in stackoverflow in chrome as “Third Party Cookies Appear To Be Disabled”

There are lots of question related the same. But none of them helped me to get rid of this error “Third Party Cookies Appear To Be Disabled”.  I get the answer as my sytem time is wrong  from that questions. Yes my sytem time was wrong at first.  But after I corrected the system time, still the error persists in Chrome 23.   The Firefox 17 is working fine for me.


Minimal counterexamples of the isomorphism problem for integral group rings

The isomorphism problem for integral group rings asks if two finite groups $G,H$ are isomorphic when their integral group rings $\mathbb{Z}[G]$, $\mathbb{Z}[H]$ are isomorphic. Quite a lot has been done towards solving this and related problems. See for example Chapter 9 in Milies, Sehgal, "An Introduction to Group Rings". Now it seems that the first (?!) counterexample has been found by Martin Hertweck in his 2001 paper "A Counterexample to the Isomorphism Problem for Integral Group Rings". He has constructed two counterexamples, the one group has order $2^{25} \cdot 97^2$ and the other group has $2^{21} \cdot 97^{28}$. Do we really have to consider such huge groups? The thesis by Geoffrey Janssens discusses Hertweck's construction in detail, and claims that this is the only known counterexample. Is this still correct?  Question. What is known about the minimal counterexamples of the isomorphism problem for integral group rings?


List of explicit enumerations of rational numbers

A well-known mathematical fact is that the rational numbers are countable, i.e. there is a bijective function  $$f:\mathbb{N}\rightarrow \mathbb{Q}$$  I am interesting in making a list of all explicit such bijections since each one that I know have a different philosophy behind it.   This is one of the more counterintuitive facts about infinite, at least when one enters inside set theory. When I explain this in the first time to anyone, he/she is surprised. Thus I think  it will be useful for showing the fact in a more clear manner or as possible exercises to show alternatives ways with respect to the standard one.


Provide sftp read/write access to folder and subfolders, restrict all else

I need to provide user access to Ubuntu 14.04 Server, only limited to certain folder. To enjoy the ssh security and not to open up new service and ports (ie, ftp), I'd like to stick with sftp. However, just creating a user and enabling ssh access is too generous - the user then can log on via ssh and see whatever there is that is viewable by everybody.  I need the user to find themselves in a specific directory after login, and, according to their privileges, read/write files, as well as create folders where permitted. No access to any file or directory above the user's "root" folder.  What would be the suggested method to achieve this? Is there some very restricted shell type for this? I tried with  $ usermod -s /bin/false <username>   But that does not let the user to cd into subfolders of their base folder.


Can I Two-Weapon fight after Two-Handed-Weapon fighting?

Pick a class that has access to the Extra Attack feature. For my example, I'll use my standby, Fighter McFighterson.  Let us say that McFighterson is 20th level, and possesses the Dual Wielder feat. He is currently holding a greatsword, and has two longswords accessible.  As a reminder, two weapon fighting says:     When you take the Attack action and attack with a light melee weapon that you're holding in one hand, you can use a bonus action to attack with a different light melee weapon that you're holding in the other hand...[snip]   And Dual Wielder:     [snip]... You can use two-weapon fighting even when the one handed melee weapons you are wielding aren’t light.   You can draw or stow two one-handed weapons when you would normally be able to draw or stow only one. ...[snip]   Can McFighterson make all of the attacks granted by Extra Attack (3, in this case) with his greatsword, drop the greatsword "for free", draw two longswords (as permitted by Dual Wielder), use his last attack to attack with one longsword, then two-weapon-fight with the second longsword?  Making the attack sequence look something like: Greatsword, Greatsword, Greatsword, Longsword1, Longsword2.    Related:


I have 10 points that represent the centres of countries. I want to show with arrows the flow (some kind of trade) from one country to another.   The way that my table of attributes is constructed is the following:  From country      X Y       To country    X_to  Y_to            Value  1                 X Y       2             X_to  Y_to            10   I want the arrows to be proportional to the value and not to be straight lines but curved as it may be the case that 2 countries exchange trade, i.e. country 1 sends to country 2 and country 2 sends to country 1.  ARCGIS 10.2


Is it possible to use an AMD A4 APU on AMD E1 mainboard?

I would like to change my AMD E1 APU with an AMD A4 APU. Is the socket BGA and BGA-413 the same? Is that possible and would it work?


Exclusive differences Profiles vs permission sets?

I understand, the differences between Profiles and Permission Sets. I just wanna ask are there some configs that make Profile or Permission Set unique.  Are there things that could only be done via permission set and not via Profiles and vice versa ?


If I SSH to a remote server, is it be possible for the admins of that machine to use my SSH session to send data back down the connection and do something to my local PC? I use DSA keys and do not allow password logins to my SSH server, and I do not allow root access. If it would still be possible despite these precautions,  could you explain how it is done with code/links so I can understand?  Another thing I am worried about is that if I connect to the remote server, the admins may be able to hijack my pts session and simply type exit to get to my PC. Again, please let me know if this is possible and if so please provide code/links  I've done a bit of googling and turned up nothing so far.


Anime where a character works to prevent his birth

I'm trying to find an anime I watched in 2005/2006. It was a short one (probably around 12-13 episodes) and I remember only one character - a dark haired guy (his name started with Y, but I'm not sure) whose biggest dream was to never been born. The point was that he didn't want to commit suicide, but simply never exist in the first place.   All I remember from the story line is that their was another guy who fought to make the dark haired guy's dream come true. In the end, he succeeds and the other one disappears/vanishes - as he has never been born.  Truth be told it was a really sad story, but I can't stop thinking about it and as it wasn't popular I can't find its title. Unfortunately, that's all I remember.  If anyone of you maybe recognise this anime? Thank you in advance!


Why does Chuck ask people that enter his house if they have 'grounded themselves'?

On the show Better Call Saul, when someone enters Chuck's house, he asks     Ground yourself?   By which he means to leave watches, mobile phones et cetera outside of the house.  Also, he doesn't have anything electrical in his house.  Why is that?


How does one evaluate $\sqrt[3]{x + iy} + \sqrt[3]{x - iy}$?

The answer to  hinged on the fact that $\sqrt[3]{35 + 18i\sqrt{3}} + \sqrt[3]{35 - 18i\sqrt{3}} = 7$. How does one evaluate such expressions?


can i install Ubuntu14.04 in my ideapad?

i'm using ubuntu 12.04  64 bit version in my Lenovo S100 ideapad. my ideapad is having 2GB RAM and Atom processor.Is there any performance and speed problems will occur if i change my OS to 14.04?


Using a hyphen when describing measures (e.g., a 300-meter asteroid)

Here's some examples. Please tell me which ones are right, and which ones are wrong, and why.   "A 350-meter asteroid impacted the Moon." "A 350-meters asteroid impacted the Moon." "A 350 meter asteroid impacted the Moon." "A 350 meters asteroid impacted the Moon."   There's also extended versions.   "A 350-meter wide asteroid impacted the Moon." "A 350-meter-wide asteroid impacted the Moon."   Etcetera. Which ones are right/wrong, and why?


When can we say a multiplicative group of integers modulo $n$, i.e., $U_n$ is  cyclic?   $$U_n=\{a \in\mathbb  Z_n \mid \gcd(a,n)=1 \}$$  I searched the internet but did not get a clear idea.


How can I update Openjdk 13 to 14, Ubuntu 20.04

I need to update Java 13 to Java 14 and how can I do that in Ubuntu. I have tried to install 14 like: ~$ sudo tee /etc/profile.d/jdk14.sh <<EOF > export JAVA_HOME=/opt/jdk-14 > export PATH=\$PATH:\$JAVA_HOME/bin >  > EOF export JAVA_HOME=/opt/jdk-14 export PATH=$PATH:$JAVA_HOME/bin   source /etc/profile.d/jdk14.sh echo $JAVA_HOME /opt/jdk-14 ~$ java -version openjdk version "13" 2019-09-17 OpenJDK Runtime Environment (build 13+33) OpenJDK 64-Bit Server VM (build 13+33, mixed mode, sharing)    but as you can see my result is still Openjdk13.


What does edge triggered and level triggered mean?

I am studying 8085 microprocessor architecture and the word edge triggered and level triggered confusing me really very much. Can anyone explain me it in layman's words ?  While studying the interrupts of 8085 named RST 7.5, RST 6.5, RST 5.5 and TRAP i came across these words and they confused me. Here i have attached one document link from which i was reading and i have mentioned my confusion diagrams.   in the document RST 7.5 -> Edge triggered RST 5.5 -> Level triggered. TRAP -> Edge triggered and Level triggered. (why ? does it make any difference?).


Wolf trip on hit during an attack of opportunity

A wolf gets a free trip attempt on a successful bite attack.  However, this trip attack is a free action, and free actions must be taken on your turn.  Does this mean that if a wolf gets an attack of opportunity, and hits, he doesn't get a trip attempt because it is not his turn?  This makes RAW-sense to me, but not intuitive sense, so I want to make sure I'm not missing something.


How does printf with multiple arguments separated by space work

I have the following printf function:  $ printf '%s %s %s\t%s\n' 100644 blob 8e1e f1.txt 100644 blob 9de7 f2.txt | git mktree   Can anyone please explain what it produces and why? I expected to have equal number of formatting options %s for each argument string but I have a lot more arguments strings here.


No return on$('input:checkbox').change(function() {?

I am testing a second solution that has been provided to me here, for checking and recording each check box that has been checked. First solution works like a charm but the second more efficient solution does not even run.  for (x in aL.results) {   aLIds.push(aL.results[x].listing_id);   aLTitles.push(aL.results[x].title);   aLQuantities.push(aL.results[x].quantity);   aLDescs.push(aL.results[x].description);   aLTaxPaths.push(aL.results[x].Tax_path);   aLTaxIds.push(aL.results[x].Tax_id);   aLTags.push(aL.results[x].tags);   aLUrls.push(aL.results[x].url);   aLPrices.push(aL.results[x].price);   aLViews.push(aL.results[x].views);   aLHearts.push(aL.results[x].num_favorers);    $('#tblListings').append(     '
' + '<input type="checkbox" name="updateListings[]" value=' + x + ' >	' + '' + aLQuantities[x] + '	' + '' + aLTitles[x] + '	' + '' + aLPrices[x] + '	' + '' + aLViews[x] + '	' + '' + aLHearts[x] + '	' + '
'   ); }  $('input:checkbox').change(function() {     alert('ah');     var uLIndex = $('input:checkbox:checked').map(function() {         return this.value;     }).get();     console.log(uLIndex); });


No single axiom stating non-Archimedeanity

An ordered field $K$ with the ordering $<$ is Archimedean if for any $x \in K$ there exists $n \in \mathbb{N}$ (where $\mathbb{N}$ is the copy of the natural numbers in $K$) such that $|x|<n$.  It is an easy task to show that for every Archimedean ordered field $K$ there is a non-Archimedean ordered field $L$ such that they are elementarily equivalent, i.e. they satisfy exactly the same first-order sentences in the language of ordered fields $(+,\cdot,0,1,<)$. (Namely, one can take the first-order theory of $K$ and extend it by all sentences of the form $c> 1+ \ldots + 1$, where $c$ is a new constant symbol. Let us call this theory $T$. Now any finite subset of $T$ has an Archimedean model. Thus, by the Compactness Theorem, $T$ has a model, which, by construction, is non-Archimedean.)  I was wondering: Is there a single first-order sentence $\sigma$ in the language of ordered fields such that any model of $\sigma$ is a non-Archimedean ordered field?  I would expect the answer to be 'No.' but cannot find where this result has been proved.


How to show that this recursive sequence is monotonic?

$a_1 = \frac{1}{2}, a_2 = 1,  a_n = \frac{1}{2}a_{n-1} + \sqrt{a_{n-2}}$ for $n \geq 3$  I assume that $a_{n} \le a_{n+1} $ , so it means that $ \frac{1}{2}a_{n-1} + \sqrt{a_{n-2}} \le \frac{1}{2}a_{n} + \sqrt{a_{n-1}} $  Base for $n=1$ : $\frac{1}{2} = a_{1} \le a_{2} = 1$ ok.   Thesis: $a_{n+1} \le a_{n+2} $, so it means: $\frac{1}{2}a_{n} + \sqrt{a_{n-1}} \le \frac{1}{2}a_{n+2} + \sqrt{a_{n+1}}$  What should I do next? I think I should use the assumption, but I don't know how to do it.  Maybe this: $\frac{1}{2}a_{n-1} + \sqrt{a_{n-2}} \le \frac{1}{2}a_{n+2} + \sqrt{a_{n+1}} $, but it gets me nowhere. Please give me some hints.


Biject all points on a plane to the real line

I understand that the continuum hypothesis implies (since there are only two infinities; discrete and continuous) that the set of points on an n-dimensional plane is equal to (can be bijected to) the points on a 1 dimensional line. Is there a proof of this for a space of arbitrary dimensionality?


Short story with mercenaries trying to board a mothballed starship

This is a short story I read about 20-25 years ago.  The plot had three mercenaries, hired to deactivate the defenses on an ancient warship found mothballed in space. The captain of the merceneries was a human woman, and her two colleagues were aliens - I vaguely remember them being cat-like.  The ship was mothballed a long time before, and its computer was left to defend it - it's using the ships weapons to stop itself being boarded. The mercenaries manage to talk to the computer and get some hints as to the code they need to turn the defenses off again, though they can't talk their way on board. So they start broadcasting every combination that it might be while trying to figure out another plan. But they've only got a week to solve the problem, or they don't get paid, and there are too many possible codes to go through them all in time.  In the end      one of them realises that the deactivation code is 'Halti', which is - apparently - the Esperanto for 'Stop'   I've tried to find it off and on for years, but with no success - I have the feeling it's part of a wider series of stories. I'm almost sure I've not dreamed it.


I'm trying to automatically mount a NAS drive on start. The command I'm using to manually mount it is:  sudo mount -t nfs 192.168.1.88:/NAS /media/nas   This works fine. This is what I'm putting in my fstab file which isn't working:  //192.168.1.57/nas /media/nas nas _netdev,auto 0 0   No doubt a basic error but my googling has failed me. Thanks very much.


How is experience gain calculated in agar.io?

Each agar.io run awards experience. I know of a few things that grant XP:  Time survived Acquiring mass Number of splits Position on the leader board  But what are the precise numbers? Are there any more factors?


How to solve this equation $x^{2}=2^{x}$?

How to solve this equation $$x^{2}=2^{x}$$   where $x \in \mathbb{R}$.  Por tentativa erro consegui descobri que $2$ é uma solução, mas não encontrei um método pra isso. Alguma sugestão?(*)  (Translation: By trying different values I've found that $2$ is a solution, but I couldn't find any method to this though. Any suggestions? )


I have this text

The setup is shown below:

%as2-From%-%srcfilebase%.%srcfileext%

  I need regex to match to: src=""https://support.comp.com/inlineimages/Notify/Oct2014/25899/1413838988355.png""  and src=""/inlineimages/1413839088730.png""  However, when I use the regex img src="".+png"" It matches to:

The setup is shown below:

%as2-From%-%srcfilebase%.%srcfileext%

  Why is it including the  stuff between the two hyperlinks? Any help is appreciated.  I'm using regex generator:


Rotation of group of rigid motions of cube is isomorphic to $S_{4}$

How can we show that a rotation of the group of rigid motions of the cube is isomorphic to $S_{4}$? This is what I have done:  The group of rigid motions of the cube can be assorted to 4 cases.  First, rotation by the diagonal.  Second, rotation by the line connecting the two centers of the opposite line.  Third, rotation by the line connecting the two centers of the opposite face.  Fourth, identity.


I have two directories images and images2 with this structure in Linux:  /images/ad   /images/fe   /images/foo     ... and other 4000 folders  and the other is like:    /images2/ad   /images2/fe   /images2/foo   ... and other 4000 folders  Each of these folders contain images and the directories' names under images and images2 are exactly the same, however their content is different. Then I want to know how I can copy-merge the images of /images2/ad into images/ad, the images of /images2/foo into images/foo and so on with all the 4000 folders..


I can't understand the proof of theorem 8.17 from Hartshorne's "Algebraic Geometry". Namely, he says that we have an exact sequence  $$ 0 \to \mathcal J'/\mathcal J'^2 \to \Omega_{X/k} \otimes \mathcal O_{Y'} \to \Omega_{Y'/k} \to 0  $$ and there are $x_1, \dots,x_r$ such that $dx_1, \dots, dx_r$ generate a free subsheaf of rank $r$ in a neighborhood of $y \in Y$. It follows that $\Omega_{Y'/k}$ is locally free. Why?


Cannot visualize a WMS in Geoserver from a JPG file

I'm using a JPG file (8bit unsigned), together with a .jgw and the .jpg.aux.xml having the projection. The image displays well in ArcGIS and QGIS.  Now I want to create the image in Geoserver 2.11.0 as a 'WorldImage' store, and then create a Web Map Service around it. But the image doesn't work in 'Layer preview'. You see nothing.  When I try to consume the WMS in ArcGIS, this is the error I get.    Any ideas?


What Window Management Options exist for OS X?

I'd like to do something with my windows on OS X, where something includes options like re-arranging, moving, re-sizing, remembering positions, cloning across Spaces, etc. What options exist?  Rules   One app per answer. Use this format for the first two lines of your answer: ## [app name](link to website) [App Store](link to appstore) (price)    Check for duplicates before adding new answers.  If you find a duplicate, vote it down and encourage its poster to upvote the original entry instead (and remove the dupe). Include short description about what this Window Managing app does.  What makes this Window Manager app different than the others? Is it focused on re-sizing using only the keyboard? Is it focused on moving using only mouse gestures? Etc.


Review conference papers under supervisor name

I work as a researcher in a private company and my supervisor, who was previously working as a university professor, asked me to review papers for a conference he's co-organizing. He mentioned the review will be under his name.   Is it normal for a researcher with a PhD to review papers without any type of exposure in return? Do you have tips on how to proceed? I have to mention that I come from a different field.


different types of array declaration in c++

I have just been starting with C++ and I have come across multiple types of array declaration in C++  int data[3];   and other type is,  int *data= new data[3];   What is the difference between the two? Since, I have not allocated memory in the first case will I overwrite memory which may already be in use and potentially cause segmentation error?


Does using Views & Panels on every page will effect site performance (speed)?

I am building a community site.  The site would have A LOT of data on it.  I thought about creating a lot of content pane with views, and use them with panels - for every page.  I will be happy to hear your thoughts about this idea.   It will make my site much slower? Or it depends entirely on different things?   if so, I will be happy to get more information. I know I need to cache,  but I don't really know how to do that on the user's computers.   Thanks!


I'm trying to compile a document that only works with an up-to-date distribution, so I'd like to know: how do I update my distribution? Please provide screenshots where appropriate.  List of answers           To keep an eye on what’s going on at CTAN you may subscribe to the  or the RSS feed feed://www.mail-archive.com/ctan-ann@dante.de/maillist.xml


Ring and Subring with different Identities

Is there an example of a ring $S$ with identity $1_S$ containing a non-trivial subring $R$ which itself has an identity $1_R$, but $1_R\neq 1_S$ (or equivalently $1_S\notin R$). I'd also like to know under what conditions the identities have to be equal. I know they must be equal if $S$ has no zero divisors, since for every $r\in R$ we have $(1_S-1_R)r=0$  In other words: Is the category of unital rings with identity-preserving morphisms a full subcategory of the category of rings (where morphism are only required to respect addition and multiplication)?


Show that $\text{trace}(A)\leq \sqrt{n}\sqrt{\text{trace}(AA^t)}$ where $A$ is in $M_{n}(\mathbb{R}).$  We know that $\text{trace}(A) =\sum_{i}\lambda_i$ where $\lambda_i$ are eigenvalues of $A.$ Then I was wondering if we could show that the eigenvalues of $AA^t$ are $\lambda_i^2$ then we could apply the AM-GM inequality to complete the proof. So we know that $A$ and $A^t$ have the same eigenvalues, but can we use this conclude that $AA^t$ have $\lambda_i^2$ as eigenvalues?


Group with order $p^2$ must be abelian . How to prove that?

Possible Duplicate:          I must show that a group with order $p^2$ with $p$ prime must be a abelian. I know that $|Z(G)| > 1$ and so $|Z(G)| \in \{p,p^2\}$.   If I assume that the order is $p$ i get $|G / Z(G)| = p$ and so each coset of $Z(G)$ has order $p$ which means that each coset is cyclic and especially $Z(G)$ is cyclic. Can I conclude something by that?


i just have a ubuntu live cd for some critical situations... I have a vaio F11 and a win10 as OS on it,but  windows can't boot from HDD, so I tried to access files using ubuntu live,but it says:  Error mounting /dev/sda3 at /media/ubuntu/14FCB981FCB95E24: Command-line `mount -t "ntfs" -o "uhelper=udisks2,nodev,nosuid,uid=999,gid=999,dmask=0077,fmask=0177" "/dev/sda3" "/media/ubuntu/14FCB981FCB95E24"' exited with non-zero exit status 14: The disk contains an unclean file system (0, 0). Metadata kept in Windows cache, refused to mount. Failed to mount '/dev/sda3': Operation not permitted The NTFS partition is in an unsafe state. Please resume and shutdown Windows fully (no hibernation or fast restarting), or mount the volume read-only with the 'ro' mount option.   now please help me on this,I have some important data on my HDD...show me if there is anyway to copy them on an external HDD.


Visa requirement for Chinese passport holder going from Shenzhen to Hong Kong

We are a group of 6 people from Malaysia, going to Shenzhen (2 days) then train to Hong Kong (4 days) and ferry to Macau (2 days), then back to Malaysia. All hotels are booked with booking.com.  The problem is that one person in our group is a Chinese passport holder with a valid Malaysia visa. Going to Shenzhen is ok but from Shenzhen to Hong Kong, we don't know if she needs a visa to enter Hong Kong since we are going to stay there for 4 nights. (7-day visa free applicable?). We will take a ferry to Macau (7-day visa free applicable to enter Macau on transit to Malaysia) for another 2 nights, then flying off to Malaysia.  Does anybody know this visa rule?


What is the best way to clone a Linux partition onto a smaller partition?

I've currently got an 80 GB  (yes, I know, that's why I'm changing it...)  Linux device that's about 80% free, and I want to change it to a 40 GB  partition using one of the previous RAID 0 partitions. I've got enough spare space on another large partition for all the files, and the best method I thought of doing the switch is:   cp -a all files on the filesystem to a directory under a large partition Repartition cp -a all files back to a new partition   The thing is, I'm worried about special file properties (it's a Linux root device); will cp -a keep all the necessary file properties so the new partition is bootable afterwards? Am I missing another way of doing it?


Logistic regression with binary dependent and independent variables

Is it appropriate to do a logistic regression where both the dependent and independent variables are binary? for example the dependent variable is 0 and 1 and the predictors are contrast coded variables -1 and 1 ?


Would there be any significant balance implications for letting a player forfeit their action to take a second bonus action?

As the title suggests, I'm wondering if there would be any significant balance implications for letting a player forfeit their action to take an additional bonus action (but not the other way around).  I know there would be balance implications for the other way around so that's why I said that.  I also know that RAW they're not at all interchangeable but as a house rule option maybe?


How to make new IEnumerable collection and return it?

I need to pass an IEnumerable and a delegate to my method, and then filter it and return an IEnumerable collection with numbers that pass filter. Func<int, bool> filter = x => x % 3 == 0;   public static IEnumerable<int> Filter(IEnumerable<int> numbers, Func<int, bool> filter) {     foreach (int number in numbers)      {         if (filter.Invoke(number))          {             // add number to collection         }     }      // return collection }  I have tried creating a new collection like this: IEnumerable<int> result = new IEnumerable<int>();  But it is not possible since IEnumerable is an abstract class. How should I create and return this collection? I know that there is a lot of easy ways to do this, but can't find any.


How to calculate the entropy of passwords?

Here is a cartoon about password entropy.   I dont quite understand how the entropy is calculated in the cartoon assuming they are calculate correctly. But in general, I dont have much idea about how password entropy is calculated.


How much damage would I be incurring if I turn down an informal postdoc offer?

So I have been in touch with a prof for a few months about being a postdoc in his group. He promised (verbally) one year of funding saying he was not sure if his grant proposal for my second year of funding would be successful. After being in touch with him over six months, he let me know that he the proposal has been successful and he now has funding for my second year. In the mean time, my opinion about being a postdoc and going the academic route have changed quite a bit due to family and other personal circumstances and I want to move into the industry [I have an offer in hand too]. My question is, how bad would it be, in terms of loss of face, if I said no to being a postdoc with the prof? I haven't signed a contract with him or anything and all communication between us has been informal. How do I even begin to explain things to him? I haven't even given a hint to him so far.


What's wrong with XKCD's Frequentists vs. Bayesians comic?

makes fun of a frequentist statistician who derives an obviously wrong result.  However it seems to me that his reasoning is actually correct in the sense that it follows  the standard frequentist methodology.   So my question is "does he correctly apply the frequentist methodology?"    If no: what would be a correct frequentist inference in this scenario? How to integrate "prior knowledge" about the sun stability in the frequentist methodology? If yes: wtf? ;-)


Legendre symbol: Showing that $\sum_{m=0}^{p-1} \left(\frac{am+b}{p}\right)=0$

I have a question about Legendre symbol.  Let $a$, $b$ be integers. Let $p$ be a prime not dividing $a$. Show that the Legendre symbol verifies: $$\sum_{m=0}^{p-1} \left(\frac{am+b}{p}\right)=0.$$  I know that $\displaystyle\sum_{m=0}^{p-1} \left(\frac{m}{p}\right)=0$, but how do I connect this with the previous formula?  Any help is appreciated.


Let $G$ be a simple graph on $n$ vertices. If $G$ has $k$ components and every component is complete prove that: $$|E| \le \frac{(n-k)(n-k+1)}{2}$$ I'm asking for advice.


Why does it put on record that I had a edit rejected, if it conflicted with a later one?

If I do an edit, and while it is pending (being approved), someone comes and does the same edit, my edit gets rejected by 'Community'. It doesn't contribute to my edit ban, but it does still contribute to my 'number of rejected edits', which is shown to all the reviewers when I edit something. This seems pointless, as in fact, my edit was good, and was, in a way, implemented. I shouldn't be penalised for it.  I don't think that this should increment the rejected edits number for no reason, even if it still doesn't award the +2 rep and increment the accepted edits number either.


Looking at several machines with a Gold 6146 CPU, I found that they all have different (sets of) core IDs, e.g.  grep core.id /proc/cpuinfo  core id         : 0 core id         : 0 core id         : 4 core id         : 4 core id         : 1 core id         : 1 core id         : 3 core id         : 3 core id         : 2 core id         : 2 core id         : 10 core id         : 10 core id         : 9 core id         : 9 core id         : 19 core id         : 19 ....   This one has each core ID appearing twice because of hyperthreading. It is somewhat surprising to see a non-monotonous sequence of core IDs, and even left-out values: the 6146 is a 12-core CPU, but the highest ID here is >12.  On another machine, it gets weirder still:  core id         : 0 core id         : 0 core id         : 4 core id         : 4 core id         : 1 core id         : 1 core id         : 3 core id         : 3 core id         : 2 core id         : 2 core id         : 11 core id         : 10 core id         : 8 core id         : 9 core id         : 10 core id         : 19   Here, core IDs do not occur in pairs anymore, and the total number of unique IDs is larger than the number of physical cores (16 vs 12).


Is adding/removing tags too minor an edit?

Ive just started doing reviews on stackoverflow, and after reading some of the debates about minor edits here on meta and developing my personal thoughts thoughts on the topic, I wonder about the case for adding tags.  I've seen that adding/removing a single or even a couple of tags is often considered too minor by other reviewers. However, this included at least one occasion when the single added 'java' tag was key which brought the entire question into context.  Unfortunately I havent been able to find that example again.  While I can see how pedantic minor spelling or grammer tweaks can and should be considered too minor, with tags you get more than a slight increase in readability. It helps bring the right people in on the question, helps give context to the question, helps remove confusion when incorrect tags are removed, and depending on the tag type also adds colouring to any code samples.  So is it ok to approve simple tag additions/removals, or should they be considered too minor?


Label expression in ArcGIS gives TypeError coercing to Unicode need string or buffer NoneType found?

I try to build stacked label expression in ArcGis  10.3.1 with this expression:  [name3] + '\n'+ [results]      name3 and results are two columns in the attribute table. But I get this error:  typeerror coercing to unicode need string or buffer nonetype found   I read  but didn't find any solution.  This is the attribute table:


Confused about GPU having hundreds of processors inside it

I just started learning about parallel programming course on Udacity and already I am kind of confused. Here at this video segment:    We're told that the average GPU has thousands of ALUs and Hundreds of processors. I am confused by the "hundreds of processors" part. Why are there that many? Shouldn't it be just one...? GPU does stand for graphics processor unit. Isn't a GPU like a CPU, one processor with the thousands of ALUs inside, BUT entirely specialized for certain tasks? How do these "processors" come into play?   If I'm wrong then I assume that each processor has perhaps about 10 (because 10* hundred CPU's = 1000s of ALUs) ALU's inside it? Is there a layout I can see so I can verify this?   Thank you.


Prove that $\sqrt 2 + \sqrt 3$ is irrational

I have proved in earlier exercises of this book that $\sqrt 2$ and $\sqrt 3$ are irrational. Then, the sum of two irrational numbers is an irrational number. Thus, $\sqrt 2 + \sqrt 3$ is irrational. My first question is, is this reasoning correct?  Secondly, the book wants me to use the fact that if $n$ is an integer that is not a perfect square, then $\sqrt n$ is irrational. This means that $\sqrt 6$ is irrational. How are we to use this fact? Can we reason as follows:  $\sqrt 6$ is irrational  $\Rightarrow \sqrt{2 \cdot 3}$ is irrational.  $\Rightarrow \sqrt 2 \cdot \sqrt 3$ is irrational  $\Rightarrow \sqrt 2$ or $\sqrt 3$ or both are irrational.  $\Rightarrow \sqrt 2 + \sqrt 3$ is irrational.  Is this way of reasoning correct?


Help identifying obscure sci-fi movie from late 1970s/early 1980s

I need help jogging my memory about a low budget science fiction film (or perhaps TV series) from the late 1970s or early 1980s.  The first scene of the movie depicts the characters on a disabled luxury cruise ship stranded in space. That's all I remember. I don't think it's Battlestar Galactica or Buck Rogers.


What should i do when my recurrent neural network doesn't improve?

I am training an LSTM network using Tensorflow 2, is there a way to debug it to see if its learning or to know what areas should be adjusted ?  Is there a way to debug to know if its the data, the model or the hyper-parameters ?  Is there a way to have more informative approach to what to work on in LSTM to make it better ?  Simple model:  single_step_model = tf.keras.models.Sequential() single_step_model.add(tf.keras.layers.LSTM(32,                                            input_shape=x_train_single.shape[-2:])) single_step_model.add(tf.keras.layers.Dense(1))  single_step_model.compile(optimizer=tf.keras.optimizers.RMSprop(), loss='mae')   And the loss:  Train for 200 steps, validate for 50 steps Epoch 1/10 200/200 [==============================] - 1s 7ms/step - loss: 0.0332 - val_loss: 0.0766 Epoch 2/10 200/200 [==============================] - 1s 6ms/step - loss: 0.0290 - val_loss: 0.0746 Epoch 3/10 200/200 [==============================] - 1s 6ms/step - loss: 0.0271 - val_loss: 0.0328 Epoch 4/10 200/200 [==============================] - 1s 6ms/step - loss: 0.0280 - val_loss: 0.0270 Epoch 5/10 200/200 [==============================] - 1s 6ms/step - loss: 0.0258 - val_loss: 0.0328 Epoch 6/10 200/200 [==============================] - 1s 6ms/step - loss: 0.0249 - val_loss: 0.0274 Epoch 7/10 200/200 [==============================] - 1s 6ms/step - loss: 0.0345 - val_loss: 0.0364 Epoch 8/10 200/200 [==============================] - 1s 6ms/step - loss: 0.0276 - val_loss: 0.0445 Epoch 9/10 200/200 [==============================] - 1s 5ms/step - loss: 0.0273 - val_loss: 0.0430 Epoch 10/10 200/200 [==============================] - 1s 6ms/step - loss: 0.0273 - val_loss: 0.0428 ```