I got this equation by predicting grassland biomass growth from precipitation and soilnutrient.  How can I convert it into original power function and how to interpret scientifically.   logNDVI <- 0.36 + 64.8*log(precipitation) + 0.9*(soilNutrient)  P <- 0.01; R2= 0.72 and residual standard error=0.45   Thank you!


What is different between "<<-EOF" and "<<EOF" in bash script?

I did google this topic and all results are talking about <<EOF. But I saw scripts using <<-EOF, but I can not find anywehre by googling. Thus, What is different between <<-EOF and <<EOF in bash script? Thanks a lot.


I'm new to Blender and am experimenting using it to design a landscaping project. I have a DXF file with contour lines for the land and have managed to import these into Blender. My aim is to have a full surface that reflects the site, and where I can start manipulating the slope and adding shapes onto it.  I now have a series of lines with heights, but that are not connected to each other and don't have an edge around them. After a long time trying to just join the edges using a combination of selecting them and choosing "Connect vertex path" or "Merge vertices > at center" (when connect didn't work) I thought maybe I'd be able to create a plane from it. However this only created small patches of planes so I'm guessing I've done something wrong. I was thinking as a next option I could just create a plane of the same size underneath it and manually drag each point up to match a point on one of the contour lines. This would probably take quite a while - is there any better option out there?


Prove that all ideals in $\mathbb{Z}[x]$ are generated by two elements.

I was trying to prove that $\mathbb{Z}[x]$ is noetherian, so every ideal in $\mathbb{Z}[x]$ is finitely generated.  I feel that all ideals in $\mathbb{Z}[x]$ are essentially generated by two elements - a polynomial and the smallest integer belonging to the ideal.  Let $a(x) \in I$, where $I$ is an ideal in $\mathbb{Z}[x]$, be a polynomial whose degree is the least. Let $b(x)$ be another polynomial whose degree is more than $a(x)$ then $r(x)=a(x)-b(x)q(x) \in I$ becomes the polynomial of the smallest degree (we first assume that $r(x)$ is a non constant polynomial). So $r(x)$ has to be zero.  If $r(x)$ is a constant in $\mathbb{Z}$ and  let $r $ be the least positive integer in $\mathbb{Z}[x]$. If $r(x) \in (r)$ then we are done, or let $d=(r(x),r)$ then I will be generated by $(a(x),d)$. What I think is that I am going wrong in the last paragraph. Can someone point out my mistake.


How do you link to applications in the Android market?

When posting app links, I'm always using a link on Cyrket or AppBrain -- becuase I can't get a link to anything in the official Android Market.  But I have seen some links out there for use w/ Android itself ( ''market://'' protocol ):  market://details?id=de.schildbach.oeffi   (as seen @ )  Is it possible to web-link to apps in the Market so that a non-Android user can link to the appropriate Market page in a non-Android web browser?


I was trying to figure out $\sum^\infty_{n=0}\frac{1}{n^4-1}$ and I got $$\sum^\infty_{n=0} \frac{1}{n^2+1}$$ As a part of it, I've tied to solve it using partial fractions with complex numbers with no success. Do any of you know how to derive the solution?(I got $\frac{1}{2}(1+\pi\coth(\pi))$ from wolfram alpha)


Tag input too low when editing on Meta Stack Exchange

When editing a question on Meta Stack Exchange, the input field for the tags is too low. Or the tags are styled with a too large margin-top.


Does the verb “enable” take a bare-infinitive complement like “let” or a to-infinitive complement like “allow”?

How can you predict which verbs take which type of infinitive as their complements? For example, is the to before open here mandatory, forbidden, or optional?        The Gold Monetization Scheme will be revamped to enable people open a hassle-free gold deposit account.   The Gold Monetization Scheme will be revamped to enable people to open a hassle-free gold deposit account.      In other words, does the verb enable:   take only a bare-infinitive complement the way let does? take only a to-infinitive complement the way allow does?  take an optional to before its infinitive complement the way help does?   How can you tell which verb does which thing?


Morphisms of schemes arenot determined by their underlying map of points.

In vakil's notes, exercise 6.3.L state that morphism of schemes $X\rightarrow Y$ are determined by their induced maps.And not determined by their underlying map of points. By Yoneda's lemma, $X\rightarrow Y$ determined by $h_X\rightarrow h_Y.$ What's the example that they are not determined by their underlying map of points.


Are we living in a simulation? The evidence

I am not questioning whether the simulation topic is outside science. I am asking what evidence there is or could be to resolve whether we are or not.   Living in a simulation has been a topic for philosophy since at least Descartes, with his 'evil demon not less powerful than deceitful'. Zuangzhi's 'Now I do not know whether I was then a man dreaming I was a butterfly, or whether I am now a butterfly, dreaming I am a man' could be argued to be a statement of the same idea. What I am interested in is, is can we get beyond speculation and make headway on this? How does the evidence stand, what tools do we have, and what implications might the different answers have?  Here I quickly summarize some of the main positions:    (2003), Nick Bostrom, makes the case we are in a simulation, on the balance of probabilities   (2017), Ringel & Kovrizhin, makes the case such a simulation is impossible using classical computers.  But that leaves quantum computers.  (2014) gives a more detailed idea of what being in a simulation might mean, as a kind of peer-to-peer reality  demonstrates a serious argument that the simulation hypothesis is the best answer to the Fermi Paradox.  Although as recently discussed on here, the existence of this paradox is open to dispute, and relies on a range of assumptions.   Anyone got anything else evidence based? Any models, or discussions of implications?


Convergence of infinite series of complex numbers

This has been bugging me for some months since our lecturer, a fields medalist, mentioned that he couldn't solve it when he was our age, yet had had two students submit solutions to it (during our introductory analysis course). It was proposed to him by another mathematician at Cambridge who taught him then, and is still there now, who had this problem on his list of "problems for enthusiasts". ( is the lecturer).   Let $z_i \in \mathbb{C}$ be a series of complex numbers with $\displaystyle \lim_{i \to \infty}{|z_i|}=0$. Show that we can choose signs $\alpha_i \in \left\{ {-1,1} \right\}$ such that $\displaystyle \sum_{i=1}^{\infty} \alpha_iz_i$ converges.  He deemed it fruitful to first try and prove the following weaker statement to get an idea of what's involved, yet I have not managed this either.  Let $z_i \in \mathbb{C}$ be a series of complex numbers with $|z_i|=1$. Show that we can choose signs $\alpha_i \in \left\{ {-1,1} \right\}$ such that $\displaystyle \sum_{i=1}^{\infty} \alpha_iz_i$ remains bounded. (In fact, it would seem that we can make $|\displaystyle \sum_{i=1}^{k} \alpha_iz_i| \leq \sqrt2 \ \ \forall k$).  Any ideas, thoughts, or solutions would be greatly appreciated.


Does the partial derivative of $\langle x'|\alpha\rangle$ with respect to $x'$ equal $|\alpha\rangle$? Why?   Note: $|\alpha\rangle$ is an arbitrary ket, $x'$ is an eigenvalue, and $\langle x'|$ is an eigenket corresponding to $x'$.  In particular, I do not understand how these two expressions are equivalent:  $$\langle x' - \Delta x' | \alpha \rangle = \langle x' |\alpha\rangle - \Delta x' \frac {\partial} {\partial x'} \langle x' | \alpha \rangle $$


how to convert unknown characters in java?

Please don't mark it as duplicate.   I am using Blowfish Algorithm to Encrypt and Decrypt a Contents in a File. The problem is the output characters of encrypted file having too much of special characters   SPECIAL CHARACTERS (Encrypted text) :- Ž81‡Ç¬ú²±DN¢HÜ4ºÜºT÷.Ê+ŠÀ  after that i had converted the special characters to hex it gives the value as  8E383187C7ACFAB214B113444EA248DC34BADCBA54F7032ECA2B8AC03C6B95C67D2F46F586E4CD86  if i tried to convert this to string i cant get the same encrypted text  Following java code for converting hex to string  package bytearray;  import java.io.DataInputStream; import java.io.FileInputStream; import java.io.IOException; import java.io.InputStream; import java.io.PrintWriter; import java.util.Arrays; import javax.xml.bind.DatatypeConverter;    public class ByteArray {       public static byte[] toByteArray(String s) {         return DatatypeConverter.parseHexBinary(s);     }      public static void main(String[] args) throws IOException {         String balaji  ="8E383187C7ACFAB214B113444EA248DC34BADCBA54F7032ECA2B8AC03C6B95C67D2F46F586E4CD86";          byte[] pri = toByteArray(balaji);         String value = new String(pri);         System.out.println(value);       }  }   Please help us how to convert the hex to string.  Expected Output :-  Ž81‡Ç¬ú²±DN¢HÜ4ºÜºT÷.Ê+ŠÀ  Obtained output:- �81�Ǭ���DN�H�4�ܺT�.�+��


Find $\int _{-\infty}^{\infty}\frac{1}{x^{12} + 1} dx$ elementarily

Ho to find the following integral $$\int_{-\infty}^{\infty}\frac{1}{x^{12} + 1} dx $$using parts by  substitution, partial fractions, etc. but not Cauchy's residue theorem?


What is a person called who likes to use big words to make others think they are superior?

What is a person called who uses:   Complicated vocabulary when a simple answer would be sufficient? Uses complex vocabulary to make others think they are highly educated Is unnecessarily verbose


why is my attr_accessor working for getting but not for setting?

ruby version: 2.3.4  I am fairly new to Ruby and can't figure out why the following code will not update my variable.  class Blah   attr_accessor :update_me    def initialize     @update_me = 6   end    def addy     puts update_me     if update_me == nil       update_me = 1     else       update_me += 1     end   end  end   Here is my input and the results from irb   > a = Blah.new  => #<Blah:0x007fdcfe819dd0 @update_me=6>  > a.addy 6 NoMethodError: undefined method `+' for nil:NilClass   from (irb):35:in `addy'   from (irb):42   from /Users/tracy/.rvm/rubies/ruby-2.3.4/bin/irb:11:in `<main>'   In my addy method it is clearly seeing the initial value of the update_me variable as 6, and it is passing by the if == nil statement as expected, but when it tries to update the value I get a nil:NilClass error. There is something I appear to be fundamentally misunderstanding here.


Why is a deductive closure an intersection of maximally consistent sets?

Full Question: Show that if $\Delta(\Gamma)$ is the deductive closure of a consistent $\Gamma$ then $\Delta(\Gamma)$ is the intersection of all maximal consistent sets of formulas $\Lambda$ with $\Gamma \subseteq \Lambda$.  I'm really stuck with this question, I honestly don't know how to even start. Can someone please provide some assistance?


Is it possible to use Java as a scripting language in unity?

I wonder if its possible to use Java as a scripting language in unity to create a basic 2d game?


Message response options symbols intermittently not loaded on mobile chat

When selecting a message on MSE chat to reply about half of the time only the flag icon loads. The other icons don't load. The buttons are there, because replying or starring a message is possible when you guesstimate the right location for the trigger.


Well why the depletion region of the pn junction is decreased in forward bias condition and not minimized? Current will start flowing neutralizing all donor ions and so there will be no depletion region left.


extracting text from MS word files in python

for working with MS word files in python, there is python win32 extensions, which can be used in windows. How do I do the same in linux? Is there any library?


Calculate $\lim_{x \to \infty} x-x^2\ln(1+1/x)$

$\lim_{x \to \infty}  x-x^2\ln(1+1/x)$ I tried to write it as a fraction and use L'Hospital Rule but it will still be a indetermination. The answer seems to be $1/2$. Can somebody help me, please?


Removed Python 3 and now Ubuntu Software Center, terminal and other applications don't work

I am a new Ubuntu user running Ubuntu 13.04.  I've been trying to install and use a DeDRM tool, but I've been having problems doing so. I was following some directions that said I needed a version of Python 2.7, but not anything Python 3.0 or later (because 3.0 versions are missing some necessary libraries?). I tried to install Python 2.7.5.6, but it didn't work. I thought it was probably because I had the later version of Python, so I went through terminal and removed Python 3.3, so I could install the earlier version of Python.  Now that I've uninstalled Python 3.3, a lot of applications no longer work, including the terminal and the Ubuntu Software Center. I have no idea how to fix this problem now.


What i am doing wrong here . and if i am correct then can any one explain to me how $1=-1$

Let suppose  $(-1)(-1)=(-1)²$  if i take square root on both sides then   $\sqrt{(-1)(-1)}=\sqrt{(-1)²}$  after multiplication and cancelation   $\sqrt{1}=(-1)$  which is wrong although i suppose a correct equation  $1=-1$  where i am wrong and if i am correct then I just want to know why it is so


Cannot get object in specific index in Java

I am creating simple Android project which contains login Activity. The problem is I tried to reach the object in specific index and tried for loop, but it always return last object in sequence.   public Result<LoggedInUser> login (String username, String password){      try {         // TODO: handle loggedInUser authentication         GetData myData = new GetData();         usersdata = myData.getUsers();         for (User user : usersdata) {             if (user.UserName.trim() == username && user.Password.trim() == password) {                 LoggedUser = user;             } else LoggedUser = null;         }          return new Result.Success<>(LoggedUser);     } catch (Exception e) {         return new Result.Error(new IOException("Error logging in", e));     } }


Since yesterday my pcie wireless adapter doesn't show up anymore in the drop down menu (upper right corner of the screen) or in any other menu as far as I saw. It's an Asus PCE-AC68 and it's using a Broadcom BCM4360 driver. I tried a solution I found on this website (  ) but it threw a dpgk error during the reinstalling another solution I tried ( )  didn't work since when I tried  sudo modprobe -rv bcma wl or  sudo rmmod bcma wl I got permission denied, I tried to remove bcma but I couldn't since it was in use, I also tried to cancel everything with the name bcmwl-kernel-source but when I tried to install the package again I got an error, I reinstalled a fresh Ubuntu 20.10 (before I had 20.04) erasing everything from the SSD but not even this fixed the issue. I'm sure the wireless adapter works as I use it on Win 10. Edit: I've just run the command lshw -C network and the broadcom network results UNCLAIMED Edit 2: now that I found the network was unclaimed I was able to find a possible solution related to secure boot and by going inside the BIOS changing secure boot from Windows to Other OS solved my issue. Strange it worked till yesterday and suddenly stopped though Edit 3: the secure boot solution worked for the 20.10 but not for the 20.04, to fix the issue on Ubuntu 20.04 I followed the six steps here:


Counting % overlays of shapefile polygons with buffers

I have previously asked question here but it was closed because I did not react fast enough twice already and I have put in the comments why those questions do not answer my problem. Nevertheless, my problem is still the same: I have a set of points (meteorological stations) with 5km buffers around them. Additionally, I have a set of polygons (municipalities) in which those stations are located. Each station buffer can be over 1,2,3... polygons and those can be completely different polygons.  I would like to have data on how much of the buffer is filled by each polygon but I was not able to find a function or a way to do it. So for example for point A I would have that in the buffer of 5km there is 80% of polygon B and 20% of polygon C as the output, so 4 values, two for IDs of the polygons and 2 for the percentage overlap (it could be only 2 values for other buffer or 6 etc. etc.).  Main difference to the other similar question provided is that I have 2 vector layers (Buffer with 500 buffers and Municipalities a shape file with 500 different polygons). Previous questions were analyzing this question in situations in which I know precisely the polygons and buffers analyzed, at least that is how I understood them, so after trying to use those approaches on my dataset I was not able to replicate them.  I have also commented on the approaches posted in the previous question but did not get any response to those sadly. Bottom line being I understand those approaches and was able to replicate them in a simple setting but when I do not have specific buffers/polygons I do not know how to execute them. Another way of approaching this problem was to use join attributes by location -one-to-many and then getting averages of the duplicate results, only problem is that then I take average of polygons instead of their weights corresponding to % of intersection with the buffer. In my case I do not know what polygons of the shapefile are going to intersect what buffers, or even if the buffer is going to be intersected by 1,2 or more polygons


Should it be "there is a total of 378 vehicles" or "there are a total of 378 vehicles"?

I'm not sure if the subject is the total (in which case it would be "there is") or the vehicles (in which case it would be "there are").  I suppose another option would be to remove "total of" from the sentence, but assuming that "total of" is left in, I'd like to know what the proper wording would be.


Recovering admin password on used netbook

I had never heard of Ubuntu, but after using it with the limited guest access I would like to have more access. Play with it and see if I can learn to use it properly. I don't want to uninstall it, I just want to assign a new admin and password for full access. The previous admin no longer owns this netbook. I have made no serious attempts to recover the password because, although I am uneducated with modern technology, I am smart enough to know clicking the wrong button can cause severe damage. I really want to experience Ubuntu thoroughly and form my own opinion.


I usually hear people talk about Newton's 2nd Law like it's a, well, law, as in it relates several defined concepts. I had always thought of it as the definition of force. I'm pretty sure I'm wrong in this respect, but I can't figure out how. If mass times acceleration isn't the definition of force, it must have another definition, and Newton's 2nd Law relates these two concepts. Is it incorrect to think that every physical value that doesn't have base units must have a definition? If not, why not? And if so, what is the definition of force?  I asked my professor this question, and he said that force is defined to be something that changes the velocity of an object. Given that acceleration is the time derivative of velocity, this sounds like a roundabout way of saying $F=ma.$   If I'm actually right, and Newton's 2nd Law is a definition, why do people treat it (and name it) like a law?


Partitioning a natural number $n$ in order to get the maximum product sequence of its addends

Suppose we have a natural number $n \ge 0$.  Given natural numbers $\alpha_1,\ldots,\alpha_k$ such that   $k\le n$ $\sum_i \alpha_i = n$   what is the maximum value that $\Pi_i \alpha_i$ can take?  I'm quite sure that there is a theorem telling me the result, but I cannot find it. For sure an upper bound is $n^k$ but I'm searching for a real upper bound. I'm pretty sure that upper the bound should be $n^2$, but I don't know I could prove it.


This is the second mouse dying on me because of a poor switch ! Under most operating systems there is a option to set the max time interval in which two mouse clicks are processed as on double click.  Logically there has to be a way to set a minimum double click time interval!  I surely could replace the broken switch but there are costs for the new switch, time and basic soldering needed for that. Obviously this should be the last possible step to take.  Firstly I want to try to let the computer handle the broken mouse. I am searching a fix for windows and especially for linux (ubuntu) systems.  E: as Matt Eckert mentioned the problem is that the mouse switch is gotten loose and is producing two signals with just one key press. I've never mentioned that I want to set up anything within th mouse. Sorry for the misunderstanding, I thought that this problem occurs very often so that everyone understands the problem with the give information.  Under Windows there is only the option to set the maximum time interval in in which a double click is recognized. I need to set up the minimum time interval. In other word a double click should only be recognized if the time difference between two mouse clicks is at least for example half of a millisecond.


Editing a previous message posts a new one instead

When editing a message in the new mobile chat, a new message is posted instead of replacing the edited one.  Steps I followed to reproduce:   I posted a message in (new mobile) chat.   Then I selected the message and clicked the pencil icon in the menu bar.   The previous message was displayed, and I edited it, and then clicked the pencil button on the side.   Instead of editing the message, a new message was posted.   I believe this is a bug.


When is there going to be a PhpMyAdmin version available for Ubuntu 19.10 without PPA installation?

I'm just wondering, when is PhpMyAdmin going to be ready for Ubuntu 19.10? Should we wait until the next Ubuntu version?  I know there's a related topic about this () but as nothing I've tried seems to solve my problem, I'm thinking of downgrading to 19.04 again.  P.S.: This question is different because I wanted to know if there was going to be a date for an official release of PhpMyAdmin for this version of Linux, but looks like it will take some time before this gets done.  I found two excellent alternatives for PhpMyAdmin:       So, this topic can be closed.  Thanks!


I am aware that when we try to report a post, it cannot be done twice. But starting last week, I am experiencing this crazy thing. It shows I raised two types of report for the same post. Kindly have a look at the preview:    It shows both Spam as well as Rude or Abusive. Is it the intended behaviour or a bug? Let me know if I need to take down the question too. :)


Finding counterexamples for infinite series.

Give either a justification or a counterexample for each of the following statements about real series. $\quad(a)$ If $ka_k\to0$ as $k\to\infty$, then $\sum a_k$ converges. $\quad(b)$ If $\lim\limits_{k\to\infty}\frac{a_{k+1}}{a_k}$ exists and equals $L>1$, then $\sum a_k$ diverges. $\quad(c)$ If $\sum a_k$ converges and $\lim\limits_{k\to\infty}\frac{a_k}{b_k}=1$, then $\sum b_k$ converges.  I think all propositions are false.  But struggling to find counterexamples.  Is there some sort of systematic way of constructing counterexamples for these sorts of series?  Can someone explain their thinking process in giving counter examples for the above?


multi-threading or multi processing in laravel php

I am developing a php application with laravel. In my application I need to do some data fetching from a number of servers. In order to speedup the results I have to send those requests in the same time. I've found laravel queue but the problem is that the I need to get information back from the queue. Another solution is php pthreads but I'm having a very hard time installing it. Is there any way (multithreading / multiprocessing) to do seprate jobs async.


Im using this command:  /execute if entity @e[type=minecraft:zombie,distance=100] run say HEY!  ignore the say part, but I want it to detect a zombie in a radius from the command block, logically this should work right or am I just being an idiot?


What is the command to kill/close notifications?

By default, I have to wait for a few seconds for the notifications to fade off.   I'd like to know the command to kill them immediately, so I can bind it to a shortcut key. (Super+N seems good right now.)  PS: I tried installing notify-osd, but the terminal says it couldn't find the package notifyosdconfig.


Generate a large number of the same byte

I'm generating a binary file as test data for a piece of software. The test data should consist of a long array of the same byte. If it was a zero byte I would use /dev/zero. Is there a command to transform the zeros from there into another byte, or a command to do a similar thing?  I came up with this bash script, but this solution doesn't feel ideal. It can only generate a fixed number of bytes. There is surely a way to do this with a simpler script.  for i in $(seq 5); do     echo $'\x10' done


How to make ends of a beveled curve sharp?

I want to make the ends of these curves sharp, and i want it to remain closed even if i move the bevel start and end point of the curves, the curves are generated by ivygen, i want to make it look like they're growing, but i want the ends sharp


Theoretical proof of the constant of speed of light $c$ in vacuum in all frames of references

Is there any theoretical proof for the constant speed of light in all frames of references? I know it is experimentally proven but just curious.


Template issues getting ajax search results

I'm trying to put search results into a div with ajax. The issue is I'm getting errors saying undefined function have_posts() when the the search template is accessed. It also took issue with get_header() which was in the search-results.php but I took it out. Here's how I have it setup.
    <form role="search" method="get" id="searchform" action="http://myurl.com/" >     <input type="text" value="" name="s" id="s" />     <input type="submit" id="searchsubmit" value="Search" />    </form>

      And here is the search-results.php template. I'm wondering if maybe I'm not passing the search results to the template.
  <?php if (have_posts()) : while (have_posts()) : the_post();  ?>
<a title="Permalink to this post" href="<?php echo get_permalink(); ?>"><?php the_title(); ?>
   <?php endwhile; endif; ?>  <?php if (!have_posts()) { echo('
No results to show.
'); } ?>


Tried searching but couldn't find how to curve this in  the way I show with red lines (ms paint, sry XD)


I mean, can I copy part of the content and put it in a website?  Can questions be distributed or published?


How to remove accents and turn letters into "plain" ASCII characters?

What is the most efficient way to remove accents from a string e.g. ÈâuÑ becomes Eaun?  Is there a simple, built in way that I'm missing or a regular expression?


when I run  sudo cd /root it says sudo: cd: command not found but it works perfectly fine if I first sudo su and then do cd /root. Isn't sudo supposed to give me root privileges?


Two explanations of non-zero atomic radius

I have came across two separate explanations for why atoms have a positive atomic radius (as opposed to electrons "collapsing" into the nucleus).    The first is via Heisenberg Uncertainty Principle, where decreasing the atomic radius would raise momentum and hence kinetic energy (while potential energy decreases) - the atom would "choose" a radius that minimizes energy.  The second is kind of "just set-up and solve the Schrodinger equation" and obtain a certain atomic radius.   Are these two explanations just two sides of a single coin/a matter of interpretation? I have briefly heard that there is an equivalence between "Heisenberg" and "Schrodinger" formulation of QM - is this an instance of the equivalence?


L1 regression estimates median whereas L2 regression estimates mean?

So I was asked a question on which central measures L1 (i.e., lasso) and L2 (i.e., ridge regression) estimated. The answer is L1=median and L2=mean. Is there any type of intuitive reasoning to this? Or does it have to be determined algebraically? If so, how do I go about doing that?


Strange behaviour with PGF/TikZ and Plain TeX output routine

I noticed a strange behavior when running PGF/tikZ with pdfTeX on my Debian box : a simple session without tikz:  pdftex **\relax *Hello World *\bye   do output the page number on the page footer. On the other hand, loading tikz:  pdftex **\relax *\input tikz.tex *Hello World *\bye`   does make the page number on the footer disappear. The page size does not seems to be the cause.  Does any of you have any idea of the cause behind this behaviour?


Estimate how much large is $\lfloor \log{n!\rfloor}$

Is there a simple method to find or estimate how large  $$\lfloor \lg{n!\rfloor}$$ is ? I'd like to find (or estimate) how much digits $2017!^{2017}$ has, or how much is big that number .     I tried for some little number and general form of $$n!^{n}=\overline{a_k...a_4a_3a_2a_1} \\ k=?$$ so  I took logarithm of $n!^{n} \mapsto n\log(n!) $.  It is easy when $n$ is little number , but when go for a large number ...what we can do  ?  My question can be translate as $$n\sum_{i=1}^{n}\log(i)= ?$$


Apache 2 could not bind, address already in use

I installed Apache 2 on Ubuntu 12.10. When I try to start the service using sudo /etc/init.d/apache2 start, I get the following message.  *Starting web server apache2 (98)Address already in use: make_sock: could not bind to address 127.0.0.1:80 no listening sockets available, shutting down Unable to open logs Action 'start' failed. The Apache error log may have more information.                                 [fail]


I am using Ubuntu 16.04.  Whenever I try to access any of the TTY  Alt+Ctrl+F(1-6), it asks me for my username. I enter my username and press enter then I am supposed to type my password. However, after pressing enter at the first time (after typing my username), it keeps hitting enter like forever. I do not even have a chance to enter the password.  So, the scenario goes as follows:   I enter my username Press enter Requests password and immediately it acts as if an enter  is pressed It keeps going like this until it reaches the maximum number of login attempts. All of that happens without even touching my keyboard after the first enter hitting.   So, how to solve this problem?  Edit: I entered recovery mode and ran package fix successfully.


Sum of points and rank according to points

I am creating a game where I am calculating the user points on the basis of user activities. Everything is working fine - I got the sum of points and on the basis of points I calculated the rank. I have two columns for points calculation: pointsup (contains up points) and pointsdown (contains down points)  select sum(pointsup - pointsdown) as points  from table1 t1 join table2 t2      on t2.Id = t1.id where t1.ActivityTime BETWEEN '2015-01-01' AND '2016-01-01'  group by t1.id  order by points desc   Everything is fine, but the problem comes when I have to rank the users with same points. In this case, I have to consider the registration date: who registers first will come up first on the ranking. The registration date is in another table table3. I have tried to join this third table but the sum is behaving oddly, showing wrong sum calculation.  Can anyone help please?


Why does this not print the last element in the list.  >>> a_lst = [1,2,3,4,5,6] >>> print a_lst[-1] 6 >>> print a_lst[0:-1] [1, 2, 3, 4, 5]   I can see that if I just do a_lst[-1] it returns the expected last element.  But when I try to use it in a range [0:-1] it actually returns the penultimate element?


How can I remove the unwanted background from a scanned handwritten signature?

I need to upload my signature in a PDF document, but I do not know how to edit the background of this image.   I wish to remove the bluish-tint background, and make it pure white.   Can anyone help me with this, please?


Why is grounding required in a transistor circuit?

This picture is given in my textbook regarding an n-p-n transistor circuit:    Why is the emitter grounded? Why can't it be directly and only connected to the negative terminal of Vcc?


apt looking for i386 files, even though architecture is amd64

I am trying to use a file repository for updating linux/ubuntu on a non-connected machine. The architecture for this machine (uname -a):  x86_64 GNU/Linux   The results of dpkg --printarchitecture are:  amd64   It is a Trusty Tahr amd64 machine, and it specifically says this, for example, in the aptitude sources.list file. Also, the "About this Computer" in ubuntu specifically says the machine is 64-bit. So, I installed the amd64 packages on the machine. However, when I try to do apt-get update, I get errors such as:  W: Failed to fetch file:/var/spool/apt-mirror-trusty/mirror/archive.ubuntu.com/ubuntu/dists/trusty/main/binary-i386/Packages  File not found   So, in other words, even though it is a 64-bit machine, apt is inexplicably trying to read i386 packages. Why is it doing this and how can I make it use the 64-bit packages?  Note that there is nothing in sources.list that specifies i386.  The only uncommented line in the sources.list file is:  deb file:///var/spool/apt-mirror-trusty/mirror/archive.ubuntu.com/ubuntu trusty main restricted universe multiverse


This question comes from this  debate at SuperUser Forum. I have asked it here too because:     It appears not to be only a technical question, but a language question too. Most of the answers in the referred thread until now seem to me most like "Everybody says 32 bit, so it must be correct" kind, instead of reason and logic based.   The question is: as long as a computer that works with, say, 64 bit(s) uses more bit(s) for computing than a computer that works with, say, 32 bit(s), should we say ... ?   32 bit operating system 32 bits operating system   What if we change "operating system" by "graphics card", "motherboard", or "version of the program"?


With bash, I used to executed ls *.JPG to list all JPG files of a directory, but since macOS suggested me to move to zsh, this simple command doesn't work anymore and gives me the following error:  $ ls *.JPG       ls: illegal option --   usage: ls [-@ABCFGHLOPRSTUWabcdefghiklmnopqrstuwx1%] [file ...]   What the appropriate equivalent with zsh ?


Pracitcal design difference between header and cpp files

Comming from a mostly Java background I recently started learning a bit of C++. I'm trying to create a class that describes a LinkedList. Since I want this class to be something like an external library, so I can use it in other applications, I need it to be declared as a header file.  I understand that from a design point of view C++ needs both a header and a cpp file, where the header will mostly contain declarations and the implementation will be left for the cpp file.  What I don't understand though is what is the actual purpose of the above design technique. The point of being able to quickly go through the header file and read the comments about the functionality of each method seems moot to me, since C++ (or at least my Codeblocks editor) supports the /** comments like Java so it is much easier to create an object of the class and simply hit the . button to open the methods description menu, and read any description I like in a more orderly and structured manner than going through a header file.  Also I noticed that the program runs fine if put everything inside the header file and completly ignore the cpp file.  So my question boils down to whether I should just implement everything in the header file, or whether this is considered unacceptable C++ coding practice and if so, why.


File attachments other than images and links

I know you already have images and links as file attachments. But what if somebody wants to attach a word document to their question in Writers Stack Exchange?  This would really help because then I wouldn't have to post a link to a forum thread about my short story which is about lions. I could just post the word document directly and it would really save some time.


How to write a SQL SELECT query to find content in one table that is missing link to the other?

Two table employee and department each table has id and name column. Assume there are numerous content with both field populated and department id reference in each employee table record. Question is How to find all the department names with no related employees in them?


Michelson-Morley Experiment Why 90-degree rotation

Why the apparatus is rotated by 90 degree? If it is not rotated, there is still path difference between two lights. So why it is rotated?


Goofy looking alien robots lose a "Kleptonite Ball" towed behind their spacecraft

I remember watching this on TV in the United Kingdom in the late 1970s or early 1980s. I only saw one episode, and the ending resolved very little, leading me to believe that it was a pilot for a TV series that ended up not being made as opposed to a made for TV movie.   It was live action, but the non-human characters were puppets or animatronics, not actors in costumes. The main characters were the goofy looking alien robot crew of a spacecraft - their design was vaguely similar to the robots from the Cadbury's Smash advertising campaign.  Some other details that I remember:   One of the aliens was named "Gadget". Another one of the aliens had black armour; his character description in the TV guide's advertisement for the show had the comment "talks as black as he looks". Everything in the Universe was made of matter, "don't matter", or a mixture of matter and don't matter called "Kleptonite" (not 100% sure about that name). The spacecraft was towing a ball of Kleptonite behind it in a crate. The Kleptonite ball was lost and fell to Earth. According to the aliens, Earth was made of "don't matter". One of the humans who found the Kleptonite Ball was into fortune telling and mistook it for a crystal ball.


How to get my laptop to detect SD cards inserted into its built-in card reader?

My laptop has a built-in SD Card reader but it cannot detect one when inserted. Here is the result when I type lspci from the terminal:  00:00.0 Host bridge: ATI Technologies Inc RS480 Host Bridge (rev 10) 00:01.0 PCI bridge: ATI Technologies Inc RS480 PCI Bridge 00:06.0 PCI bridge: ATI Technologies Inc RS480 PCI Bridge 00:07.0 PCI bridge: ATI Technologies Inc RS480 PCI Bridge 00:12.0 IDE interface: ATI Technologies Inc IXP SB400 Serial ATA Controller (rev 80) 00:13.0 USB Controller: ATI Technologies Inc IXP SB400 USB Host Controller (rev 80) 00:13.1 USB Controller: ATI Technologies Inc IXP SB400 USB Host Controller (rev 80) 00:13.2 USB Controller: ATI Technologies Inc IXP SB400 USB2 Host Controller (rev 80) 00:14.0 SMBus: ATI Technologies Inc IXP SB400 SMBus Controller (rev 83) 00:14.1 IDE interface: ATI Technologies Inc IXP SB400 IDE Controller (rev 80) 00:14.2 Audio device: ATI Technologies Inc IXP SB4x0 High Definition Audio Controller (rev 01) 00:14.3 ISA bridge: ATI Technologies Inc IXP SB400 PCI-ISA Bridge (rev 80) 00:14.4 PCI bridge: ATI Technologies Inc IXP SB400 PCI-PCI Bridge (rev 80) 00:18.0 Host bridge: Advanced Micro Devices [AMD] K8 [Athlon64/Opteron] HyperTransport Technology Configuration 00:18.1 Host bridge: Advanced Micro Devices [AMD] K8 [Athlon64/Opteron] Address Map 00:18.2 Host bridge: Advanced Micro Devices [AMD] K8 [Athlon64/Opteron] DRAM Controller 00:18.3 Host bridge: Advanced Micro Devices [AMD] K8 [Athlon64/Opteron] Miscellaneous Control 01:05.0 VGA compatible controller: ATI Technologies Inc RS482 [Radeon Xpress 200M] 04:00.0 Ethernet controller: Realtek Semiconductor Co., Ltd. RTL8111/8168B PCI Express Gigabit Ethernet controller (rev 01) 05:04.0 FireWire (IEEE 1394): O2 Micro, Inc. Firewire (IEEE 1394) (rev 02) 05:04.2 SD Host controller: O2 Micro, Inc. Integrated MMC/SD Controller (rev 01) 05:04.3 Mass storage controller: O2 Micro, Inc. Integrated MS/xD Controller (rev 01) 05:09.0 Network controller: Ralink corp. RT2561/RT61 rev B 802.11g


Search All Fields In All Tables For A Specific Value (Oracle)

Is it possible to search every field of every table for a particular value in Oracle?  There are hundreds of tables with thousands of rows in some tables so I know this could take a very long time to query. But the only thing I know is that a value for the field I would like to query against is 1/22/2008P09RR8. <  I've tried using this statement below to find an appropriate column based on what I think it should be named but it returned no results.  SELECT * from dba_objects  WHERE object_name like '%DTN%'   There is absolutely no documentation on this database and I have no idea where this field is being pulled from.  Any thoughts?


Let ∼ be an equivalence relation on a topological space X such that each equivalence class is connected and the quotient space X/ ∼ is connected. Show that X is connected.  My  thinking that:  let $p\colon X \to Y$ be a quotient map  as  that if each set $p^{-1}({y})$ is connected, and if $Y$ is connected, then $X$ is connected.   I don't know the proper proof   Pliz help me


A teaser on center of mass of right circular cone?

How can a distinction be made between the centre of mass of a right circular cone    As a uniform solid ($\frac{h}{4}$ from base, where is $h$ is height) and  That composed of infinitesimally small thickness of right triangles of the same height and base (same as radius of cone). In which case it apparently appears to be $\frac{h}{3}$ from base.


Optimize SEO: 2 websites or 1 main website and subdomain?

I'm working on a WordPress website of a little company, let say: www.xxx.com.  Now they want a different website for their workshops.  What is the most optimal construction thinking of SEO?  1) www.xxx.com + www.xxx-workshops.com  2) www.xxx.com + www.xxx.com/workshops  3) www.xxx.com + workshops.xxx.com


USB Not Recognized after Invalid Pull Out

I have a problem, caused by me. I just bought a NAND usb stick 2 TB which worked out of the box.  I tried to copy 36GB into it. That of course took too long so, I put my laptop on suspension to not interrupt the process, (that's what I thought). The process stopped of course, and I tried to delete half copied files. This also took too long so I closed the window and tried to delete the from command line which also took to long so I stopped the process and pulled out my usb stick.  Since then my stick is not recognized.  I can see these on journlactl  kernel: usb-storage 3-1:1.0: USB Mass Storage device detected Jan 24 06:40:36 192.168.2.7 kernel: scsi host6: usb-storage 3-1:1.0 Jan 24 06:40:36 192.168.2.7 mtp-probe[29780]: checking bus 3, device 6: "/sys/devices/pci0000:00/0000:00:14.0/usb3/3-1" Jan 24 06:40:36 192.168.2.7 mtp-probe[29780]: bus: 3, device: 6 was not an MTP device Jan 24 06:40:36 192.168.2.7 upowerd[3864]: unhandled action 'bind' on /sys/devices/pci0000:00/0000:00:14.0/usb3/3-1/3-1:1.0 Jan 24 06:40:36 192.168.2.7 upowerd[3864]: unhandled action 'bind' on /sys/devices/pci0000:00/0000:00:14.0/usb3/3-1 Jan 24 06:40:37 192.168.2.7 kernel: scsi 6:0:0:0: Direct-Access     NAND     USB2DISK         0.00 PQ: 0 ANSI: 4 Jan 24 06:40:37 192.168.2.7 kernel: sd 6:0:0:0: Attached scsi generic sg3 type 0 Jan 24 06:40:37 192.168.2.7 kernel: sd 6:0:0:0: [sdc] Attached SCSI removable disk Jan 24 06:41:07 192.168.2.7 kernel: nouveau 0000:01:00.0: Enabling HDA controller Jan 24 06:41:13 192.168.2.7 kernel: ACPI: \_SB_.PCI0.PEG0.VID_: failed to evaluate _DSM Jan 24 06:41:14 192.168.2.7 sudo[29855]:     User : TTY=pts/0 ; PWD=/home/User ; USER=root ; COMMAND=/bin/lsusb Jan 24 06:41:14 192.168.2.7 sudo[29855]: pam_unix(sudo:session): session opened for user root by User(uid=0) Jan 24 06:41:14 192.168.2.7 sudo[29855]: pam_unix(sudo:session): session closed for user root Jan 24 06:45:19 192.168.2.7 kernel: brcmsmac bcma0:1: wl0: brcms_c_d11hdrs_mac80211:  txop exceeded phylen 153/256 dur 1730/150 Jan 24 06:47:02 192.168.2.7 dbus[1784]: [system] Activating via systemd: service name='net.reactivated.Fprint' unit='fprintd.se Jan 24 06:47:02 192.168.2.7 systemd[1]: Starting Fingerprint Authentication Daemon...   With lsusb I have this  Bus 002 Device 003: ID 0a5c:5802 Broadcom Corp. BCM5880 Secure Applications Processor with fingerprint touch sensor Bus 002 Device 002: ID 8087:0024 Intel Corp. Integrated Rate Matching Hub Bus 002 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub Bus 001 Device 004: ID 1bcf:2895 Sunplus Innovation Technology Inc.  Bus 001 Device 003: ID 413c:8197 Dell Computer Corp.  Bus 001 Device 002: ID 8087:0024 Intel Corp. Integrated Rate Matching Hub Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub Bus 004 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub Bus 003 Device 005: ID 045e:07fd Microsoft Corp. Nano Transceiver 1.1 Bus 003 Device 006: ID ffff:1201   Bus 003 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub   I think   Bus 003 Device 006: ID ffff:1201   is the records for my USB.  I have Centos 7 with kernel 5.4 and xforms as window manager.  I don't know what to do.


Find the sum : $\displaystyle\sum_{i=0}^n \frac{2^i}{1+x^{2^{i}}}$

$\displaystyle\sum_{i=0}^n \frac{2^i}{1+x^{2^{i}}}$  What technique is applicable here? I can't find a way to manipulate this sum to make it telescope. Just guide me.


Unable to read image from file Java.Using Netbeans

I'm trying to create a small program that read images from a file. I'm getting at least 2 errors pointed on the line 25 and 41, would you help me to fix these errors please? Thank You  public RoadSafetyAuthority() {     initComponents();      //dispaly fisrt image     showImage(pos); // Line 25 }  int pos = 0;   public String[] getImages() {      File file = new File(getClass().getResource("/Images/Information Signs").getFile());     String[] imagesList = file.list();     return imagesList; }         //display   the image by index     public final void showImage(int index) {          String[] imagesList = getImages();         String imageName =  imagesList[index]; // Line 41         ImageIcon icon = new             ImageIcon(getClass().getResource("/Images/Information Signs" + imageName));         Image image =  icon.getImage().getScaledInstance(jImageLabel.getWidth(),jImageLabel.getHeight(), Image.SCALE_SMOOTH);      }   private void jBtnNextActionPerformed(java.awt.event.ActionEvent evt) {                                               pos = pos - 1;      if(pos >= getImages().length) {         pos = getImages().length - 1;     }      showImage(pos); }                                          private void jBtnPreviousActionPerformed(java.awt.event.ActionEvent evt) {                                                  pos = pos -1;      if(pos < 0) {         pos = 0;     }      showImage(pos); }                    Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException at assignment1.RoadSafetyAuthority.showImage(RoadSafetyAuthority.java:41) at assignment1.RoadSafetyAuthority.<init>(RoadSafetyAuthority.java:25) at assignment1.RoadSafetyAuthority$3.run(RoadSafetyAuthority.java:157) at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:311) at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:758)


EDIT: I asked the question poorly, so what follows is an edit of the original. When submitting an abstract for a presentation on research that is based on joint-work, should all authors be listed or only the presenter(s)?


How to install Windows 10 on Ubuntu 18.04 operating system?

Currently I use ubuntu 18.04 as main operating system. and I need to install windows 10. I don't want to format my ubuntu. Because I usually do my work in ubuntu.


Given $f = f(u(t), t)$, is it possible to find the following derivative? ($f$,$u \in \mathbb{R}^n$, $t \in \mathbb{R}$)  $$ \frac{\partial f}{\partial||u||^2_2} $$  I am aware of the following derivatives:  $$ \frac{\partial||x||^2_2}{\partial x} = \frac{\partial ||x^Tx||_2}{\partial x} = 2x $$  So I can invert it to give me (elementwise division in the RHS)  $$ \frac{\partial x}{\partial||x||^2_2} = \frac{1}{2x} $$  This step does feel like abuse of notation I find it hard to convince myself of its validity.  If it's right though, I could just apply the chain rule to find  $$ \frac{\partial f}{\partial u} \frac{\partial u}{\partial||u||^2_2} $$  However, knowing that both $f$ and $u$ are a function of $t$, I am somehow doubting my own reasoning. Or does that just mean that the derivative will still be a function of $t$ and I have nothing to worry about? Can anyone shed some light?  UPDATE: I'm now doubting the existence of  $$ \frac{\partial u}{\partial ||u||^2_2} $$  because $u = u(||u||_2^2)$ is not injective. Is the inversion step I did above legitimate? Is there another possible approach?


Do you need to submit an itinerary to get a Chinese visa? And do you have to stick to it?

There are certain countries which in order to be granted a visa you must submit your intended itinerary. My friend tells me that he thinks China is one of those countries.  What do independent travellers do? We're thinking of hitch-hiking across China without a precise plan. But if we have to submit an itinerary for the visa does then lock us in to a planned route after all?  Is it just bureaucracy where they make it look complicated but in practice it turns out to be easy?  (If it makes a difference we will have Australia or UK passports.)


I've been tasked with gathering performance metrics on a few database servers that have one TempDB data file.  It seems prevailing wisdom is to have one TempDB data file per core up to a certain point.  Both servers in question have 4 CPUs, so we're going to add three more on each.  My question is which performance metrics should I gather to get a solid depiction of where my servers are at?  I want to gather data pre-change and post-change for comparison.


what makes a NullPointerException when getting data from firestore?

When I tried to test to find a document that is not in my firestore, I don't know why it sends a nullPointerError. What is the cause of this error? This is my code to get the list of documents that I want. In this case, I use userID as some arbitrary string that is not in my firestore. If I tried to test it with a document that is available in my firestore it works. I was expecting for an empty list when I use an arbitrary userID. In the test console it said that the NullPointerException is coming from line "return db.runTransaction(tx -> {". This question is different from  as I already tried if(budgetRef==null) return budgets but it didn't work. Thank you return db.runTransaction(tx -> {             List<Budget> budgets = new ArrayList<>();             ApiFuture<QuerySnapshot> budgetRef = tx.get(db.collection("users").document(userID).collection("budgets").orderBy("start_date", Query.Direction.DESCENDING));             for (QueryDocumentSnapshot budgetDocument : budgetRef.get().getDocuments()) {                 Budget budget = createBudgetByDocument(budgetDocument, tx);                 if(budget.getStart_date().compareTo(currentDate) <= 0 && budget.getEnd_date().compareTo(currentDate) >= 0){                     budgets.add(budget);                 }             }             return budgets;         }).get();


Relative pronouns "where" and "when": where can they be omitted?

I know the "omitting-rules" regarding the relative pronouns who/which/that and whose. How does it work with where and when? In the first sentence I cannot omit where but I can easily omit when in the second sentence. What is the rule?   I saw John in the shop where you bought your brown T-shirt. I met Laura on the day (when) I missed the train to Barcelona.


What are the best textbooks on electrodynamics for graduate and undergraduate students?


What are the effective communication channels for effecting change to SE?

It seems clear at this point that MSE is not a useful mechanism for pointing out problems on SE sites and getting resolution for them.  It is useful in some ways. If SE staff ask questions about future actions being undertaken, there is a non-zero chance that they will pay attention to some of those responses and take them into account. While the new site layout still did happen despite lots of people not liking it very much, the powers that be were responsive to specific issues about certain aspects of it. So clearly, if SE staff ask for feedback, there is a non-zero chance that the feedback may matter.  Also, posting bug reports on MSE does sometimes lead to those bugs getting solved, in many cases.  But when it comes to non-bug issues with Stack Exchange as a network, it has become abundantly clear that asking a question on MSE will accomplish nothing. There are many lines of evidence for this.  One of them being that :     Often (and more often recently) I've heard colleagues dismiss meta feedback.   Another line of evidence is a more recent event. There have been dozens of MSE posts about the "Hot Network Questions" list, many of them speaking quite negatively on its effects. These range from issues about how it causes a flood of users due to detecting controversial questions rather than good ones, to having to see a list of question titles that seem... less than professional. Things have occasionally been done, but these have been pretty minor. Regex filters for certain keywords and the like.  However, a few Twitter posts managed to find their ways into the eyes of a SE developer. This user managed to get approval to exclude IPS from the HNQ list, then implement that exclusion, and push it out into the live network.  Within one hour!  Equally rapidly, a post appeared on MSE, .  Now that is what I call an effective communication channel. In a scant few hours, SE company policy on the HNQ shifted visibly and dramatically, from an apparent course of "meh, whatever" to "OMG, we gotta fix/ditch this!"  My overall question is this: what communication channels can we use to get similar response times to user problems? Obviously, all the Meta posts about HNQ's problems had little effect, compared to a few tweets.  So, do SE users need to become more active on Twitter? Who should we be tweeting our issues to in order to get them heard? How should such tweets be composed?  Do SE users need to be making blog posts, and if so, where? What would be the most effective means of catching the attention of SE staff, such that our concerns will be taken seriously?  Note: This question is not about lambasting SE for not listening on Meta. That's a ship that has already sailed. So feel free to take comments on this subject elsewhere. I'm genuinely asking about what the best way to successfully communicate important issues to SE, such that they will actually respond to them.


Why does ruby need self explicitly in this method?

In the code below, starting_node isn't being interpreted as a setter method if I omit self; it becomes a local variable.  class Stack   attr_accessor :starting_node   def push(node)     ...     self.starting_node = node     ...   end end   Why is the explicit self needed when it works implicitly elsewhere?  How does variable assignment work if this:  local_variable.=("some string")   is invalid, that is what is it if not a method?


How can I apply a limited palette to a photo, while still keeping the value variations within the original image?


How is light slowing down in a medium thought of in the photon picture?

The speed of light in any medium besides vacuum is smaller than $c$. In a classical way, I just look at that as a wave that propagates less fast, the change in EM-field is passed on slower. How should I imagine that when thinking of light as being photons? Are they slowed down and accelerated again? What is the consequence of accelerating a massless particle?


How to present state and country picklists with dependency logic in a Lightning Component?

It's not too hard to present the Contact/Account  themselves, but the dependency filtering where when you select "United States" as the country only the 50 or so relevant states are presented seems hard to do.  I don't see anything helpful in the  component. The subject is not mentioned in the  documentation so I am assuming the dependency logic not addressed there - or is it?  I haven't found a paid or free component on the  for this.  Beyond that we seem to be back in the territory of each having to get hold of the data somehow - e.g. via a web service call to the  or in Apex through this somewhat hacky  but hard to leverage in Apex  technique - and then each writing our own client-side logic.  Is there a good ready made solution to this problem that I haven't found yet?  PS  Did some experimenting with  and with a bit of caching added the data for the default state and country picklists can be generated in about 100ms. So if no better solution comes along, I'll use that code - added below in an answer - at the server-side and write a bit of custom client-side code.


Make calls from another Android phone over Internet

I have 2 Android phones. First phone is in country A. Of course it has an Internet connection over WiFi. Second phone is in another country B, as me. So, I need to make phone calls while I'm in country B (over Internet) remotely using the phone and its sim-card, which is in counrty A. What Android software do I need?


What do people mean when they say "Notice me, senpai"?

I'm new to anime and my friends really like it. They really like to say to me "notice me, senpai!" and I don't get the reference. I could be walking to class and one of my friends would say "Can you go to the canteen?" and I would say no I can't and then, they will say "NOTICE ME, SENPAI!" Can anyone shed some light on the "notice me, senpai" reference, please?


Short story: alien planet where slow students are executed

I read this in the mid-nineties in what seemed to be new hardback book, but some of the other anthology stories seemed 'of the sixties'.  The narrator was recounting his experience visiting some alien world and getting told about their education system. Basically the poorer performing students are hanged as an incentive to the others to work harder.  This has resulted, after generations, in having a world of very high educated and quick learners. An example is the narrator needs new spectacles and a typical passing student is called over, utilising normal household items he diagnoses the lens strength required, makes and polishes the glasses and presents them to narrator, all within (I think) eight minutes.  Narrator witnesses a few more examples like this, including the ability to create a ftl spacecraft out of kitchen white goods within thirty minutes, then he returns to Earth.  On Earth he discusses the educational system with an enquiry board and the consensus is there is nothing to fear from the aliens, a typical Earth student is capable of building such an ftl spacecraft in less than twenty minutes


I have tried to evaluate the following series, $$ 1\binom{n}{1}+2\binom{n}{2}+3\binom{n}{3}+4\binom{n}{4}+........+n\binom{n}{n}=\sum_{r=1}^{n}r\binom{n}{r} $$ I have tried to evaluate using binomial expansion but I couldn't. How can I evaluate this summation?


Steam starts to open for a few seconds, then closes

I just barely installed Kubuntu and installed steam for the first time. When I try and run it it closes after a few seconds. When I run it in the Konsole I get this message.   Running Steam on ubuntu 16.04 32-bit STEAM_RUNTIME is enabled automatically /bin/bash: /home/ryker/.local/share/Steam/ubuntu12_32/steam-runtime/i386/lib/i386-linux-gnu/libtinfo.so.5: no version information available (required by /bin/bash) grep: symbol lookup error: grep: undefined symbol: pcre_jit_stack_alloc grep: symbol lookup error: grep: undefined symbol: pcre_jit_stack_alloc grep: symbol lookup error: grep: undefined symbol: pcre_jit_stack_alloc Installing breakpad exception handler for appid(steam)/version(1468023329) libGL error: unable to load driver: nouveau_dri.so libGL error: driver pointer missing libGL error: failed to load driver: nouveau libGL error: unable to load driver: swrast_dri.so libGL error: failed to load driver: swrast   I just barely installed Linux for the first time so im sorry if I have made a novice mistake. Thanks in advanced for any help!


Explanation of why doesn't heat flow spontaneously from a colder to a hotter body

The second law of thermodynamics says that heat cannot spontaneously flow from a colder to a hotter reservoir but only with the expenditure of mechanical energy. This is taken as a postulate or law in thermodynamics. Is there a deeper reason (probably from statistical mechanics) for why this is so?


Emergency mode due to filesystem checking

I have this error message. [ 0.367803 ] Initramfs unpacking failed: Decoding failed /dev/sda5: recovering journal /dev/sda5: clean, 318502/6111232 f1les, 3573298/24413696 blocks You are in emergency mode. After logging in type "journalctl -xb" to view system logs, "systemctl reboot" to reboot, "systemctl default" or "exit" to boot into default mode. Press Enter for maintenance. (or press Control-D to continue) Reloading system manager configuration Starting default target


How do you impose a character limit on a text input in HTML?


How to receive email notification of new Facebook messages in 2019?

This is a follow-up to this question: .  Facebook changed their notification options, so neither the accepted answer nor the screenshot in the aforementioned question apply any more.    I'd like to receive an e-mail message whenever someone sends me a Facebook message. What do I need to do? I checked the  configuration page, which contains the following categories:   Comments Tags Reminders More Activity About You Updates From Friends Friend Requests People You May Know Birthdays Groups Video Events Pages You Follow Marketplace Fundraisers and Community Support Other Notifications   I've read all their descriptions, and none of them mentions private messages. What did I miss?


Match what I've typed so far when scrolling bash history with the arrow keys

I'd like bash history to behave like vim's, i.e., if I start typing a command and then press the up arrow, it completes to the last command that that shares the initial string with my incomplete input. I think zsh does it but I'm only interested in bash.  Say my latest commands are  vim bubi.txt killall firefox   If now I type v and then the up arrow the command line switches to killall firefox, while I'd like it to skip to vim bubi.txt.


How does one spawn a wither skeleton with a name using a command?

In a world I am creating, I would like to summon a named Wither Skeleton. However, I don't know the commands to use.  Can someone please assist?


RAM underperforming - Shows 333 MHz instead of 667 MHz

I have an old laptop Acer 6930. There are 2 RAMs in it and both of them are 667 MHz:      When I checked in CPUZ , it shows like this:    Is there anything wrong with it?   Besides it shows as 333 MHz in CPUZ instead of 667 MHz. Laptop became very slow after having these 2 RAMs.


I just got back my Java test paper and there is one question that has been bugging me.  There was a question:  What is the output of the following program?  public class Swap {     public static void swap(int[] a){         int temp = a[1];         a[1] = a[0];         a[0] = temp;     }      public static void main(String[] args){         int[] x = {5,3};         swap(x);         System.out.println("x[0]:" + x[0] + " x[1]:" + x[1]);     } }   The thought that first came to my mind was that this was a trick question. Since the swap method return type was void, I thought that it had no effect on the int[] x array. My answer was x[0]:5 x[1]:3. I was almost certain that I got the correct answer and when I saw that I had been marked wrong, I got confused. I went to try out the actual code on NetBeans and realized that the values in the array actually got swapped! I then went on to test if this was the case for String. I typed in a similar but different code:  public class Switch {     public static void switch(String s){         s = "GOODBYE";     }      public static void main(String[] args){         String x = "HELLO";         switch(x);         System.out.println(x);     } }   The output still printed HELLO instead of GOODBYE. Now my question is why does the method not change the String but it changes the values inside an array?


proof of Gal($\mathbb{Q}^{ab}/\mathbb{Q}$) $\rightarrow$ $\hat{\mathbb{Z}}^×$

I want to prove that Gal($\mathbb{Q}^{ab}/\mathbb{Q}$) $\rightarrow$  $\hat{\mathbb{Z}}^×$ is an isomorphism by using the statement of class field theory Gal($L/K$)$^{ab}$ $\rightarrow$  $I_K/N_{L/K}I_L$ is the isomorphism where $I_L$ is the idele class group with respect to L.  I think that $L=\mathbb{Q}^{ab}$ and $K = \mathbb{Q}$ and want to prove $I_K/N_{L/K}I_L$ $\cong$ $\hat{\mathbb{Z}}^×$. $I_K$ = $\prod_{p\ is\ prime}^{'}\mathbb{Q}_p$ for $\prod^{'}$ is restricted product. But I don't know how to prove from here. Please tell me how to prove! Thanks in advance.


If i take $a$ and $b$ such as $GCD(a,b)=1$ then for the bezout lemma the inverse of $a$ mod $b$ will exist . If $GCD(a,b)\neq 1$ there can be multiple inverses of $a$ mod $b$ or simply the inverse doesn't exist ?


Question regarding plurals: Let's say I own a restaurant, and each day I feature two new soups. Are these soups called soups of the day? or soup of the days?  Then, let us say my restaurant only features one soup of the day, and I need two bowls of it... do I also call "please get me two soups of the day"?  Would I then get a snarky remark from some college bound cook that we only feature one soup of the day?  Please help clarify, and note that I am most familiar with the Chicago Manual of Style


LC50 change in units and confidence limits

I performed a dose-response experiment and I have estimated the LC50 and a confidence interval. I've been asked to provide results expressed in several units (mg/kg and mg/L).  I assume that I can transform my LC50, but I'm not sure about what happens with my confidence limits, as variance is implied in their calculation. However, . Sorry if this is a too basic question, but can I simply transform them as I do with my LC50?  That is, if (a) I transform my confidence limits from mg/kg to mg/L and (b) I fit a new regression on the mg/L values, will I obtain the same LC50 and the same confidence limits? Why?  Edit: I estimated the LC50 by a probit regression. CI calculations are based on Fieller's theorem.


My mesh is always transparent, how do i make it solid

My mesh is always transparent like this:  I want to make it solid like this


Two different login screens on Ubuntu 18.10!

So i installed Ubuntu 18.10 fresh install and i did have the normal new login screen of ubuntu gdm3. Ive been downloading gnome themes and i noticed after i did everything(idk if its from installing new themes) when locking the computer i still get the normal lock screen  And when i slide it up i get the stamdart login screen:   Lock screen  Login screen    But now it gets weird when i click on "Log in as another user" i get a new different type of log in screen, which comes when booting into ubuntu after the logo loading screen too(on this login screen the tap-to-click also doesnt work!):   2nd login screen    EDIT: Im sorry i forgot to add a question  - What is this(is this normal?) and how to set it back to default?  Added theme:  Named "flat remix"   I would be happy for your help Thanks Best Regards!


Brute force attack on a block cipher with length n

Consider a block cipher whose block length is 𝑛.  𝑁 = 2𝑛 is number of possibilities. Imagine we have 𝑡 plain text-cipher text pairs { 𝑃𝑖, 𝐶𝑖 = 𝐸𝐾(𝑃𝑖) } , where the key 𝐾 selects one of the 𝑁! Possible mappings. Now, imagine you want to brute force this encryption algorithm for the key. In each try, you generate the test key 𝐾′ and check whether 𝐶𝑖 = 𝐸(𝐾′,𝑃𝑖);  i=1,…,t.  If 𝐾′ maps 𝑃𝑖 to its proper 𝐶𝑖, we have an evidence that 𝐾′ = 𝐾. However, it could be the case that 𝐸𝐾(.) and 𝐸𝐾′(.) exactly map the 𝑡 given plain-texts to the same set of cipher-texts but map the other inputs differently. a) what’s the probability that 𝐸𝐾(.) and 𝐸𝐾′(.) are distinct mappings? b) what’s the probability that 𝐸𝐾(.) and 𝐸𝐾′(.) agree on another 𝑡′ plain-text cipher-text pairs where 0 ≤ 𝑡′ ≤ 𝑁 − 𝑡? How can I solve this problem?


Using If, then...fi command how to determine if user has input correct file format?

I am trying to create an extremely basic bash script that tells a user if they input the correct file format for the script before continuing. For example:    echo "Input .txt file here:" read file if $file = *.txt     then      echo "File is in correct format."     else     echo "File is not in correct format. Please recheck your file."     fi   What can be used to do this?   The command (below) does not work and just reports that the 'else' rather than do what I truly want.   $file = *.txt


Mathematical induction for inequalities: $\frac1{n+1} + \frac1{n+2} + \cdots +\frac1{3n+1} > 1$

Prove by induction: $$\frac1{n+1} + \frac1{n+2} + \cdots +\frac1{3n+1} > 1$$  adding $1/(3m+4)$ as the next $m+1$ value proves pretty fruitless. Can I make some simplifications in the inequality that because the $m$ step is true by the inductive hypothesis, the 1 is already less than all those values?


Ubuntu black screen on boot, AMD a6-7480 radeon r5

I always get this black screen after booting up ubuntu, unless I use "nomodeset", sure it boots but the resolution is kind of crappy. I'm using the a6-7480 radeon r5. Am I lacking drivers or something else? help please


I am provided a template and now I want to print my bibliography. The template comes with a LaTeX-class file, which contains the entry:  \usepackage[backend=biber,citestyle=ieee,sorting=none,dateabbrev=false,urldate=comp]{biblatex}  In the .tex file after some specifications such as \documentclass{myTemplte}, there is the entry \addbibresource{./library.bib}. Now, here is how I try to create one quotation:   \begin{document} \begin{figure}[h]     \centering     \def\svgwidth{\linewidth}     \import{pic/}{someFigure.pdf_tex}     \caption{Description, source: \cite{2018}.}     \label{Figure} \end{figure}  \printbibliography[heading=bibintoc]   Now, instead of a nice [1], the bibtexkey 2018 appears and the bibliography doesn't get printed at all. Can anyone think of a reason for this? Or is this question stupid to ask, because it cannot be recreated?  By the way, I am using JabRef to create my entries in my .bib file. For this particular source, I am using:   @Online{2018,   title = {Open Clip Art},   date  = {2018-07-12},   url   = {https://openclipart.org/}, }   When I run the "Bibliography" command (F8), these three errors occur:   I found no \citation commands---while reading file Report-Template.aux I found no \bibdata command---while reading file Report-Template.aux I found no \bibstyle command---while reading file Report-Template.aux


How can i zoom in really close to a model without this 'xray' effect?

I would like to know if there is any way that i can stop this from happening. I would like to be able to zoom as much as i want into / around a model without any of this stuff happening.


Does Ubuntu 18.04LTS require antivirus/malware?

(not duplicated because i'm specifying version of Ubuntu, other questions are about ubuntu without version)  Does ubuntu 18.04LTS require antivirus/malware?  wich is the best option? if yes.  i have Nod32 but i'm not sure if this is the best option, useful or at least required.  Lastest Nod32 (Linux) version is 4, looks like Nod32 does not care Linux.  is there a good, professional option?


Harddisk report low storage, but using only 25%

I bought a ultrabook in Q1 this year that has 256Gb SSD in it. After 9 months of use, Windows shows 50Gb free disk space, but used is only 67Gb as shown below...     Where has all that free space gone? Note: I included hidden files too in the report.


JavaScript (jQuery) does not react anymore after I have changed the element

I have 2 links:               When I click on the first one (a-start) I'm disabling it by removing the  element and at the same time I enable the second one (a-stop) by adding the  element:  $(document).ready(function() { $("#a-start").click(function(e){   $("#a-stop-container").html("");   $("#a-start-container").html(""); }) });   When I click on the second one (a-stop) I'm disabling it by removing the  element and at the same time I enable the first one (a-start) by adding the  element:  $(document).ready(function() { $("#a-stop").click(function(e){   $("#a-start-container").html("");   $("#a-stop-container").html("");   }) });   The problem is that it works only for the first click. For example I click on the first one (a-start), then it changes a-start and enables a-stop. But then, when I click on a-stop, JavaScript does not react anymore. The same situation the other way round. Both work fine until the  element gets changed - then I have to reload the page to get it run again.  There is no information in the console.  What am I doing wrong?


How can I show whether the series $\sum\limits_{n=1}^\infty \frac{(-1)^n}{n(2+(-1)^n)} $ converges or diverges?

While revising for exams, I came across a question where at the end of it, we had to determine whether the below series was convergent or divergent:  $$\sum_{n=1}^\infty \frac{(-1)^n}{n(2+(-1)^n)} $$  Unfortunately, other than knowing that as the series $ \sum_{n=1}^\infty \frac{(-1)^n}{n} $ converges, this series will most likely converge as the $(2 + (-1)^n)$ terms are bounded, I can't see a way of using this to determine if it converges or not.  Here's a list of some of the other ideas I've tried, which don't seem to get me anywhere:   Generalising the series - By this, I mean replacing the $-1$ for $z$ and then try and use the ratio test to see whether $-1$ is inside or outside or on the boundary of the circle of convergence - however, when I did so, I believe that the ratio test is inconclusive for all values of $|z|$, which while disappointing, is an interesting feature of the series.  - While this is usually a nice tool to use for when dealing with awkward sums, I can't see any good choice of sequences $ (a_n) $ and $(b_n)$ to choose to use. Summing consecutive terms - By this, I mean evaluating the series by looking at the sum of    $$\sum_{k=1}^\infty \frac{(-1)^{2k}}{2k(2+(-1)^{2k})} + \frac{(-1)^{2k-1}}{(2k-1)(2+(-1)^{2k-1})}$$  $$ \Rightarrow \sum_{k=1}^\infty \frac{1}{2k} - \frac{1}{3(2k-1)}$$  $\quad$ but then as we are left with parts of the harmonic series this doesn't seem like a nice way to  $\quad$evaluate it.  Other than that, I'm completely out of ideas, so any new ones (or ways to make my old ones work) would be much appreciated!


How to get path to bash script independent of whether it is sourced from bash or from another script?

I have a script, that configures some environment variables. Therefore it needs its own position, the value of $0.  I have another script that sources the first script, but it could also happen that the first script is sourced from the console.   However, neither $0, nor ${BASH_SOURCE[0]} seem to work consistently on MacOS. Here is a small example to show what I mean:   a.sh:  #!/bin/bash -eu source ./b.sh   b.sh:  #!/bin/bash -eu echo "$0" echo "${BASH_SOURCE[0]}"   Output of ./a.sh:  ./a.sh ./b.sh   Output of source ./b.sh:  ./b.sh <empty line, can't get stackoverflow to display it properly>   Not relevant, but just for completeness: output of ./b.sh:  ./b.sh ./b.sh   So, in short: If I use $0 to get the script name, it is wrong when sourced via another script. If I use ${BASH_SOURCE[0]}, it will be empty when sourced directly.   How can I get the script name in both cases?


How to block all phone calls, but only allow SMS and networking?

It's kinda disturbing when people keep calling me during work or meetings, but to me it's okay if I receive short messages or Whatsapp message because I can reply them few minutes later in a short break. I'm new Android user and wonder if my phone could do that for me.


Find the sum of $\sum\limits_{k=1}^{\infty}q^k\sin k\alpha$

Find the following sum $$\sum\limits_{k=1}^{\infty}q^k\sin k\alpha = q\sin\alpha + q^2\sin 2\alpha+\ldots+q^n\sin n\alpha+\ldots$$  I just really don't know any way to simplify that sum because of $q^k$ at $k$ term. If it was just $$\sum\limits_{k=1}^{\infty}\sin k\alpha$$ there is a hint to time that sum by $2\sin\frac{\alpha}{2}$ and use the formula $2\sin\alpha \sin\beta = \cos(\alpha-\beta)-\cos(\alpha+\beta)$, hence $$\sum\limits_{k=1}^{\infty}2\sin k\alpha\sin\frac{\alpha}{2} = (\cos\frac{\alpha}{2}-\cos\frac{3\alpha}{2})+(\cos\frac{3\alpha}{2}-\cos\frac{5\alpha}{2})+\ldots+$$  and so on. But it doesn't work here and I don't know what to do with it


Multiplication is often expressed as repeated addition.  Such as  $$5\cdot 3=5+5+5$$ $$-5\cdot 3=(-5)+(-5)+(-5)$$  Above in both the cases multiplier is positive.In case of multiplier is negative how will you express following as repeated addition  $$5\cdot (-3)$$  and   $$-5\cdot (-3)?$$  Do can they expressed as repeated subtraction from zero as follows  $$5\cdot (-3)=0-(5)-(5)-(5)$$  $$-5\cdot (-3)=0-(-5)-(-5)-(-5)$$


What is the etymology of the word "shanked"?

I have heard the verb "shanked" use to mean pulling down someone's pants, and the noun "shank" to mean stabbing someone. What is the etymology of "shanked"?  From researching online, it appears that the word has some Dutch roots with leg, but both of these slang definitions I've mentioned above do not show up much in definitions for the word. I am curious how it has gained such different meanings in common vernacular.


$x^p - t$ has no roots in $\mathbb{F}_p(t)[x]$

I am actually trying to prove that $x^p - t$ is irreducible in $\mathbb{F}_p(t)[x]$. My approach is to consider a splitting field $E$ so that: $$x^p - t = (x-\alpha_1)\dots(x-\alpha_p)=(x-\alpha)^p   \ \ \ \ \text{for some $\alpha$ in $E$}$$ Then assuming by contradiction that $x^p - t = f(x)g(x)$, then $f(x) =(x-\alpha)^r$ with $r<p$. This implies that $\alpha \in \mathbb{F}_p(t)$. Should this be a contradiction right? Why can't $\alpha$ be here?


One more question about set theory:  $A\subseteq R$ is an infinite set of positive numbers.  Assume there is a value $k \in Z$ such that for any $B \subseteq A$:  $\sum_{i=0}^\infty b(i) \le k$ where $b \in B$  Show that A is of countable cardinality  Hint: Look at the sets $A(n) = \{a\in A | a>\frac{1}{n}\}$  What I tried doing: I understand that when n goes to infinity, A(n) gets closer and closer to A. And if I could show that for all values of n, A(n) is countable, then I could show that the unification:  $A(1) \cup A(2) \cup ... \cup A(n) \cup A(n+1) \cup...=A$ is countable.   But why can you say that if there exists such a value k, such that the summary of all values of A(n) is less than k, then A(n) is countable?


How to seprate words into two lines in one cell?

The table is too wide, and I want to make it narrower by wrapping the Second under the First, how should I achieve this?  The latex code looks like this currently:  \begin{table*}[t]   \centering   \caption{Add caption}     \begin{tabular}{|c|c|c|c|c|}     \hline     \multirow{2}[4]{*}{Case Study} & \multirow{2}[4]{*}{5} & \multicolumn{3}{c|}{IBEA} \bigstrut\\ \cline{3-5}        &     & FD & P & U \bigstrut\\     \hline     \multirow{3}[6]{*}{First Second} & Run (c.) & 6090 & 6605 & 7976\bigstrut\\ \cline{2-5}        & Run (nc.) & 6665 & 6187 & 6609 \bigstrut\\ \cline{2-5}        & \#Missed & 39332 & 46001 & 46765 \bigstrut\\     \hline     \multirow{3}[6]{*}{First Second} & Run (c.) & 4418 & 4459 & 4513 \bigstrut\\ \cline{2-5}        & Run (nc.) & 4480 & 4384 & 443 \bigstrut\\ \cline{2-5}        & \#Missed & 21081 & 21897 & 21613\bigstrut\\     \hline     \multirow{3}[6]{*}{First Second} & Run (c.) & 4163 & 4251 & 4282 \bigstrut\\ \cline{2-5}        & Run (nc.) & 4241 & 4186 & 4302\bigstrut\\ \cline{2-5}        & \#Missed & 1217 & 1456 & 2524 \bigstrut\\     \hline     \end{tabular}%   \label{tab:addlabel}% \end{table*}%


Let $a_n$ and $b_n$ be natural sequence such that  $$a_n+b_n\sqrt3=(1+\sqrt3)^n$$  How can I find explicit formula for $a_n$ and $b_n$


In Win10 is there a fool proof way of discovering which App is displaying a given pop-up?

I'm working on re-purposing a Win10 laptop that has some security feature whereby all USB disks have to be approved and registered. I cannot remove that feature because I cannot see which app, service or setting is doing it. When I plug in a USB disk I get a pop-up saying the disk is not registered and cannot be used etc. The pop-up just sits there. I open Task Manager and it just has those zillion processes running. None of their names or resource usage patterns tips me off as the process that is displaying that pop-up. If I press alt-tab it just shows that pop-up as one of the running Apps but no indication of the name or location of any of the Apps. If there's visibly a Window opened up on your desktop is there a way to track down which App owns or opened that Window?  BTW it's not a browser or browser notification.  It has to be some kind of background security SW. A friend of mine was gifted her work laptop when she got laid off with the caveat that it was strictly as is. The thing is like Fort Knox and I've been unraveling all their security stuff. But I cannot find the origin or enforcer of this USB limitation.


Why is polyploidy lethal for some organisms while for others is not?

is the multiplication of number of chromosomal sets from 2n to 3n (triploidy), 4n (tetraploidy) and so on. It is quite common in plants, for example many crops like wheat or Brassica forms. It seems to be rarer in animals but still it is present among some amphibian species like Xenopus.  As I know in mammals polyploidy is lethal (I don't mean tissue - limited polyploidy). I understand that triploidy is harmful due to stronger influence of maternal or paternal epigenetic traits that cause abnormal development of placenta, but why there is no tetraploid mammals?


I can’t start pc after I dual booted ubuntu and deleted the ubuntu partition

I dual booted ubuntu on my windows operating pc, then i deleted the ubuntu partition and restarted my pc. GRUB came up and it says ”minimal BASH-like line editing is supported. For the first word , TAB lists possible command completions.Anywhere else TAB lists possible device or file completions.” So first how do i get into my windows OS and second how do i get rid of this GRUB bootloader?


Is there any way to detect file type and open it with GUI in terminal in Fedora?

For example , there are two files a.ppt and b.jpg .  And I can call a magic method to open them appropriately just like :  magic_method a.ppt magic_method b.jpg   And it open libreoffice writer and image viewer or something that fit the file type .  Is there any command or script for that?


How much extra distance to a CERN event horizon?

How much extra distance would a scientist have to travel to get to the event horizon of a mini black hole if they ever make one?


$A^{-1}$ has integer entries if and only if the ${\rm det}\ (A) =\pm 1$

So, $A$ is a $n \times n$ matrix with integer entries.  The question is to prove that $A^{-1}$ has all integer entries if and only if ${\rm det}\ (A) =\pm 1$ .  I know that $A^{-1}= {\rm adj}(A)/{\rm det}(A)$ but I have no idea where to go from there for the forward direction.  Any help here would be greatly appreciated.  For the backwards direction, I think I am okay.  I plugged the 1 and the -1 options into $ {\rm adj}(A)/{\rm det}(A)$ So, I know that $A^{-1}= {\rm adj}(A)$ or $-{\rm adj}(A)$.  Then I said that because the ${\rm adj}(A)$ is simply the matrix of co-factors of $A$, and because $A$ has all integer entries then ${\rm adj}(A)$ will have all integer entries, which will mean that $A^{-1}$ will have all integer entries.  Is that okay? Or am I missing something else?   Thank you!!``


Install driver for a BCM4360 802.11ac wireless network adapter in Ubuntu 20.04

I run into problems installing the driver for a BCM4360 802.11ac wireless network adapter in Ubuntu 20.04. I get an error when I try to install the recommended driver using the Software & Updates Ubuntu utility. Specifically, I open the Software & Updates utility, go to the Additional Drivers tab, and I select the proprietary driver under the option that appears for for the wireless card. Below are pictures of the option selected, and the error that I get when I try to install the driver.   The card is detected properly using lshw and lspci (see output below). $ sudo lshw -C network   *-network                         description: Network controller        product: BCM4360 802.11ac Wireless Network Adapter        vendor: Broadcom Inc. and subsidiaries        physical id: 0        bus info: pci@0000:04:00.0        version: 03        width: 64 bits        clock: 33MHz        capabilities: pm msi pciexpress bus_master cap_list        configuration: driver=bcma-pci-bridge latency=0        resources: irq:18 memory:d3400000-d3407fff memory:d3200000-d33fffff   *-network        description: Ethernet interface        product: Ethernet Connection (2) I219-V        vendor: Intel Corporation        physical id: 1f.6        bus info: pci@0000:00:1f.6        logical name: enp0s31f6        version: 31        serial: 1c:87:2c:5e:7c:0c        capacity: 1Gbit/s        width: 32 bits        clock: 33MHz        capabilities: pm msi bus_master cap_list ethernet physical tp 10bt 10bt-fd 100bt 100bt-fd 1000bt-fd autonegotiation        configuration: autonegotiation=on broadcast=yes driver=e1000e driverversion=3.2.6-k firmware=0.8-4 latency=0 link=no multicast=yes port=twisted pair        resources: irq:128 memory:d3100000-d311ffff   *-network        description: Ethernet interface        physical id: 2        logical name: bnep0        serial: 5c:f3:70:83:3c:b5        capabilities: ethernet physical        configuration: broadcast=yes ip=192.168.44.51 multicast=yes  $ sudo lspci 00:00.0 Host bridge: Intel Corporation Xeon E3-1200 v5/E3-1500 v5/6th Gen Core Processor Host Bridge/DRAM Registers (rev 07) 00:01.0 PCI bridge: Intel Corporation Xeon E3-1200 v5/E3-1500 v5/6th Gen Core Processor PCIe Controller (x16) (rev 07) 00:14.0 USB controller: Intel Corporation 100 Series/C230 Series Chipset Family USB 3.0 xHCI Controller (rev 31) 00:16.0 Communication controller: Intel Corporation 100 Series/C230 Series Chipset Family MEI Controller #1 (rev 31) 00:17.0 SATA controller: Intel Corporation Q170/Q150/B150/H170/H110/Z170/CM236 Chipset SATA Controller [AHCI Mode] (rev 31) 00:1b.0 PCI bridge: Intel Corporation 100 Series/C230 Series Chipset Family PCI Express Root Port #17 (rev f1) 00:1c.0 PCI bridge: Intel Corporation 100 Series/C230 Series Chipset Family PCI Express Root Port #1 (rev f1) 00:1c.2 PCI bridge: Intel Corporation 100 Series/C230 Series Chipset Family PCI Express Root Port #3 (rev f1) 00:1d.0 PCI bridge: Intel Corporation 100 Series/C230 Series Chipset Family PCI Express Root Port #9 (rev f1) 00:1f.0 ISA bridge: Intel Corporation Z170 Chipset LPC/eSPI Controller (rev 31) 00:1f.2 Memory controller: Intel Corporation 100 Series/C230 Series Chipset Family Power Management Controller (rev 31) 00:1f.3 Audio device: Intel Corporation 100 Series/C230 Series Chipset Family HD Audio Controller (rev 31) 00:1f.4 SMBus: Intel Corporation 100 Series/C230 Series Chipset Family SMBus (rev 31) 00:1f.6 Ethernet controller: Intel Corporation Ethernet Connection (2) I219-V (rev 31) 01:00.0 VGA compatible controller: NVIDIA Corporation GM204 [GeForce GTX 970] (rev a1) 01:00.1 Audio device: NVIDIA Corporation GM204 High Definition Audio Controller (rev a1) 03:00.0 USB controller: ASMedia Technology Inc. ASM1142 USB 3.1 Host Controller 04:00.0 Network controller: Broadcom Inc. and subsidiaries BCM4360 802.11ac Wireless Network Adapter (rev 03)  Any ideas of what can I do to fix this? Thanks in advance :)


Is there a way to split strings with String.split() and include the delimiters?

I'm trying to split a string with all non-alphanumeric characters as delimiters yet Java's String.split() method discards the delimiter characters from the resulting array. Is there a way to split a string like the "\W" regex pattern does, yet keep the delimiters?


Distance between footnote index and the following text

I'm having a problem with my footnotes. The problem is that the distance between the footnote index in the main text and the following text is huge. There are several threads on this and similar topics, but none of the solutions help me. The reason is presumably that I have added something to the preamble (based on an earlier problem I had) to get arabic numerals for examples in the footnotes. In the following preamble, if I remove everything from  \makeatletter downwards, the problem disappears, but I no longer get arabic numerals in my examples in the footnote. So, I want to keep the arabic numerals in the footnotes, and reduce the spacing between the footnote index in the main text and the following text to what is normal. Any ideas?   Here is a MWE:  \documentclass[12]{article} \usepackage[english]{babel} \usepackage[backend=biber, style=authoryear-comp]{biblatex} \usepackage{gb4e} \noautomath  \let\eachwordone\itshape   \makeatletter \pretocmd{\@footnotetext}{     \@noftnotefalse\setcounter{fnx}{0}%     \renewcommand{\thexnumi}{\roman{xnumi}}     }{}{} \apptocmd{\@footnotetext}{     \@noftnotetrue     \renewcommand{\thexnumi}{\arabic{xnumi}}     }{}{} \@ifpackageloaded{bidi}{% \pretocmd{\@LTRfootnotetext}{     \@noftnotefalse\setcounter{fnx}{0}%     \renewcommand{\thexnumi}{\roman{xnumi}}     }{}{} \apptocmd{\@LTRfootnotetext}{     \@noftnotetrue     \renewcommand{\thexnumi}{\arabic{xnumi}}     }{}{} } \makeatother  \begin{document}  Some text.\footnote{Some text. \begin{exe} \ex  Arabic numerals. \end{exe}} WHY IS THIS TEXT SO FAR REMOVED?   \end{document}


I seek clarification, i understand when to use data types of string, integer, double etc.When exactly would i use a data type of var (Variable)?


What happens to a radar signal when it meets with a superconductor?

A radar system has a transmitter that emits radio waves called a radar signal, consisting of electromagnetic radiation. What happens when it meets with a strong superconductor, considering the fact that a superconductor expels magnetic fields. Will there be any reflection back to the radar receiver, or will the signal be refracted?


Cannot Select Linked When Sync Selection Is Enabled

So, I'm currently developing a game with unity for which I created a bird, rigged it, and created several actions for it. I then unwrapped and textured it. But now all the actions aren't working anymore! And whenever I try to rotate/move a bone all i get is the error message: "Cannot select linked when sync selection is enabled". I think it might be related to the UV editor, but i have no clue what I should do there. I hope anyone can help!


I understand that Turkey does not belong to Schengen area. So would I need to have a visa to visit Turkey?


Prove the following trigonometric identity: $\frac{\tan A+\sec A-1}{\tan A-\sec A+1}=\frac{1+\sin A}{\cos A}$

Prove: $$\frac{\tan A+\sec A-1}{\tan A-\sec A+1}=\frac{1+\sin A}{\cos A}$$  My attempt:  LHS= $$\frac{\tan A+\sec A-1}{\tan A-\sec A+1}$$ $$=\frac{\frac{\sin A}{\cos A}+\frac{1}{\cos A}-1}{\frac{\sin A}{\cos A}-\frac{1}{\cos A}+1}$$ $$=\frac{\sin A+1-\cos A}{\sin A-1+\cos A}$$ $$\text{Using componendo and dividendo}$$ $$\frac{\sin A+1-\cos A+\sin A-1+\cos A}{\sin A+1-\cos A-\sin A+1-\cos A}$$ $$\frac{2\sin A}{2-2\cos A}=\frac{\sin A}{1-\cos A}=\frac{\sin A(1+\cos A)}{(1-\cos A)(1+\cos A)}$$ $$\frac{\sin A(1+\cos A)}{\sin^2 A}=\frac{1+\cos A}{\sin A}$$ $$\text{Which is not equal to right hand side!}$$  Have I done something wrong in the componendo dividendo step? I dont know how to use componendo dividendo rule . I saw it being used like this in some question and hence applied it here the same way. Maybe I am wrong in application of that rule. Please tell me the right way to use it. Thank you.


The number of elements in a linear independent set and the basis with a free module over a commutative ring with identity.

Suppose $M$ is a n-dimensional free module over a commutative ring with identity , is the number of elements in every linearly independent set less than or equal to n?  I have prooven it is right when R is an integral domain. Because the ring has fractional field, then we can proof that the columns of a matrix $A_{n \times m}$ is linearly dependent when $n＜ m$.  This is a classic question:   I really like the answer by Robin: . His proof shows that the columns of a matrix $A_{n \times m}$ over a commutative ring is linearly dependent when $n ＜m$. The most important is that this proof doesn't need other backgroud except pure matrix theory.  P.S:  I also construct an example about a linearly independent element in a 2-dimensional free module over an integral domain can not be expanded to a basis.


Markov chain convergence, total variation and KL divergence

I have a few related questions regarding the convergence of continuous-state Markov chains.  The theorems that I found claim that Markov chains converge in  if they are $\phi$-irreducible and aperiodic (e.g. , Theorem 4). I am confused by the fact that the way this result is phrased, it does not seem to depend on the choice of $\phi$ but $\phi$-irreducibility seems to always hold for the . Maybe I misinterpreted the definition of $\phi$-irreducibility? Could somebody help me understand this important result?  The other question that I have is: Under which conditions do Markov chains converge in KL-divergence (ideally with respect to $D_\text{KL}[P^n(x, \cdot), Q]$)? Is this known?  tells me that convergence in either KL-divergence is stronger than convergence in total variation.  Thanks!


How to delete an email address on StackExchange?

How do I delete one of my accounts/email addresses?  I have two and I just want one. I want to get rid of the old one.


Wrapping long lines that contain no spaces

I need to format extremely long strings of text. I would like to be able to specify their width, and have them wrap, with or without some special symbol to indicate that the line is wrapped. The problem is, however, that these strings do not contain any spaces. Here's an example of what I would like:  \foo{2in} {17823941237490812347123904712389407123408917234890123748912034712985712389012351}   So I would like to get an hbox containing this long number, but spanning several lines, so that I get a rectangle 2in wide.  Does anyone know of a package/trick/macro that does this?


Ground state of two electrons in one dimensional S.H.O

Let's assume I have a one dimensional harmonic oscillator. The eigenvalue of the oscillator would be $E=  (n+ \frac{1}{2}) \hbar \omega$.   Now I have two electrons (their spins are identical, I mean either both are spin up or spin down) and I want to find the ground spin state of the oscillator.   If I want to look at the triplet of the two electron system I can have two of the similar spin directions which are  $$|{\uparrow \uparrow}\rangle$$   $$|{\downarrow \downarrow}\rangle.$$   Here is how I understand it:   Since both electrons spins are are identical, we can not put them in the same quantum number. Like if we put first electron in the state $n=0$, next one has to be in the first excited state (n=1).  Do you think I can write the spin state of similar spins for the lowest ground state like this?:   $$ \alpha |{\uparrow_0  \uparrow_1}\rangle  +  \beta |{\downarrow_0 \downarrow_1}\rangle$$


Issues with Viewport and Evee render, not sure if it's a setting or a bug I have

Beginner here so I'm not even sure if this issue is because of a setting I have, or if it's a bug. So when I change viewports, I noticed the that the last two options just give me a greyed out image. Even in older projects I have which used to render correctly, it would give a trippy image. Tried recording my issue hopefully it helps!  This happens in Evee, but I also noticed that even in cycles, it would render it like this:


Load images before jQuery function ask for them

In my wordpress site i am using a quite simple jQuery piece of code:  jQuery(".first-sq").mouseenter(function(){       jQuery(".first-sq img").attr('srcset', '/wp-content/uploads/2017/01/MachineLearning_hoverx2.png');  })  jQuery(".first-sq").mouseleave(function(){    jQuery(".first-sq img").attr('srcset' , '/wp-content/uploads/2017/01/MachineLearningx2.png');  })   Now the code works but the problem is when mouseenter called it takes some time for the image to load, and you can see it being loaded. or in other words, the image revealed in portions. Is there a way to load all the images the document might use ,when document load, so when in situations like my mouseenter the image will show immediately and wont have to load?