Lagrange density for massless scalar field

I am reading a book on QFT which is stating the following.  For a massless scalar field $\phi$ the simplest possible Lagrangian is given by   $$ \mathcal{L}(x) = \frac{1}{2} \partial^\mu\phi \partial_\mu\phi  $$ with $\partial_\mu\phi\equiv\partial\phi(x)/ \partial\phi^\mu $. This can be expanded to $\mathcal{L}(x) = \frac{1}{2} (\partial_t\phi)^2 -\frac{1}{2}\nabla\phi\cdot\nabla\phi$. Which I easily see by using the definitions of $\partial^\mu$ and $\partial_\mu$ and having the mixted termes cancelling out each other.  But now the book also states that  $$ \mathcal{L}(x) = \frac{1}{2} \partial^\mu\phi \partial_\mu\phi=\frac{1}{2}(\partial_\mu\phi)^2,  $$ but I totaly fail to see this relation. To my understanding the expantion of the right part should look like  $$ \frac{1}{2}(\partial_\mu\phi)^2= \frac{1}{2} (\partial_t\phi)^2 -\frac{1}{2}\nabla\phi\cdot\nabla\phi+ \partial_t\phi\nabla\phi  $$ which is not equal to the given expantion above.  So what is my error?  [edit] Thanks for the comments that $$ (\partial_\mu\phi)^2 \equiv  (\partial_{\mu}\phi)g^{\mu\nu}(\partial_{\nu}\phi)  $$ And that I should not take the square "seriously". But If I don't take it seriously, how can I later on see that   $$ \partial_\mu \left(  \frac{\partial\mathcal{L}}{\partial(\partial_\mu\phi)} \right)= \partial_\mu\partial^\mu\phi  $$ when using the Euler-Lagrange equation?


Is $\{(0,0)\}\cup\{(x,\sin{1\over x}):x\in\mathbb{R},x>0\}$ path connected?

Is $\{(0,0)\cup\{(x,\sin{1\over x}):x\in\mathbb{R},x>0\}$ path connected?   I think it is path connected if we neglect the point$(0,0)$ it is as we can define a continuous function easily from $[0,1]$ but if we included the point $(0,0)$, then any continuous functions seems would disconnected at $(0,0)$ as the $\sin{1\over x}$ vibrate very quick between the value $0,1$for $x$ close to$0$ so for any $\delta$-ball at the origin, then choose $\epsilon={1\over2}$, then there must exist some $x\in B_{\delta}((0,0))$ where $\sin{1\over x}>\epsilon$. Is it correct? if not, is there any way can show it more clearly? Or how to present it in a better way?


Prevent VLC from starting a new instance every time a media file is opened

I'm using VLC. Its great for all media requirements. But I find this behavior annoying. Every time I open a media file, a sepearte VLC window opens up instead of stopping the current playback and play the new media. This applies to music as well as for videos. Could anyone help me in preventing it to open a new player window everytime I open a new media file.   Thanks in advance.


Why there is no badges for helpful flags?

Its like Stack Exchange sites have badges awarded for almost every small contribution you do for the site, but why there are no helpful flags badges?  A bronze badge for starting up the task of reporting the helpful flags and 50 a silver badge and 250 or 500 helpful flags should be awarded a gold badge. I don't know the reason no badges are awarded for these questions we flag as helpful.


Principal component Analysis : EVD or SVD

Could someone explain what is, from a mathematical practical point of view, PCA in data analysis and when to use it briefly ? and also when to use Eigenvalue decomposition VS Singular value decomposition ? Thanks


java.util.NoSuchElementException: No value present Java 8 Lambda

I got this. But my list is not empty and they have element with code "ADPL". Why this return me NoSuchElement ?   String retour = CodeExecutionChaine.A.getCode();     if (!lstChaines.isEmpty()) {       retour = lstChaines.stream()                          .filter(t -> t.getNomChaine() == Chaines.ADPL.getCode())                          .map(Chaine::getStatutChaine)                          .findFirst()                          .orElse(CodeExecutionChaine.A.getCode());   The enum Chaines  public enum Chaines {    ADPL("ADPL"),   ADIL("ADIL"),   ADSL("ADSL");    private String code = "";    Chaines(String code) {     this.code = code;   }    public String getCode() {     return this.code;   }  }   This is the same for CodeExecutionChaine


Create or allow for a community-wiki editable home page per tag. One where we could place essentially the tag-specific FAQ and other tag-specific links.


Spivak, Calculus, prologue, page 6 says:     Moreover, $1\ne 0$. (The assertion may seem a strange fact to list, but   we have to list it, because there is no way it could possibly be   proved on the basis of the other properties listed - these properties   would all hold if there were only one number, namely, $0$).   I did not understand what would go wrong without that assertion. $a*1 = 1*a = a$ couldn't hold true if $1 = 0$.


I need to model a fault plane below the earth's surface and find distances from different points on the surface of the earth.   I know the dimensions of the plane and its orientation but I can do that on a paper.   How to set this up in ArcGIS and find the distances I need?


In (relatively) simple words: What is an inverse limit?

I am a set theorist in my orientation, and while I did take a few courses that brushed upon categorical and algebraic constructions, one has always eluded me.  The inverse limit. I tried to ask one of the guys in my office, and despite a very shady explanation he ended up muttering that "you usually take an already known construction."  The  presents two approaches, the algebraic and the categorical. While the categorical is extremely vague for me, the algebraic one is too general and the intuition remains hidden underneath the text in a place I cannot find it.  Since I am not too familiar with categories, the explanation most people would try to give me which is categorical in nature seems to confuse me - as I keep asking this question over and over every now and then.  Could anyone explain to me in non-categorical terms what is the idea behind an inverse limit? (I am roughly familiar with its friend "direct limit", if that helps)  (While editing, I can say that the answers given so far are very interesting, and I have read them thoroughly, although I need to give it quite some thinking before I can comment on all of them right now.)


In Beamer, I use the following code \setbeamerfont{description item}{size=\tiny} but it seem not to work. How can I make description items use tiny as fontsize?


Unable to boot into windows after installing Ubuntu on a second HDD

I have windows 10 installed on a SSD in my computer. I installed Ubuntu 18.04.2 LTS onto an empty SATA drive. When I select windows from the GRUB boot list, appears as "Windows Boot Manager (on /dev/sdc1), there is an error message  saying the hardware has changed and it restarts.  When I am in ubuntu I am able to see my SSD with all of my files in the files explorer it is listed as /dev/sda2  I have attempted to use Boot repair with no success.  The log can be found here.    Any help is greatly appreciated, I am just creating a windows 10 usb from my old laptop, i have a feeling I may need it!  Here is the error message I am getting  Windows failed to start. A recent hardware or software change might be the cause. to fix the problem: 1. Insert your windows installation disc and restart the computer 2. Choose your language settings then click next 3. click repair your computer  File : \EFI\Microsoft\boot\BCD Status: 0xc0000225 Info: The Boot Configuration Data for your PC is missing or contains Errors   Thanks again


How do I get MAAS and Juju to recognize proxy settings in a deployment?

So, I have Ubuntu 12.04 LTS, installed MaaS from the initial bootup, and then added JUJU. I'm behind a proxy, so, added proxy to /etc/apt/apt.conf and also to /etc/wgetrc. Doing that I could then use maas-import-pxe-files.  Setup my environment, everything seems fine, but when I boot the nodes up they can't resolve archive.ubuntu.com. Is there somewhere I have to set my proxy information so it's passed onto the nodes that connect to the MaaS server? I don't see any action in any squid logs, and not sure where I should put my proxy to the outside world so it should be passed on.  Any assistance is greatly appreciated!


I want to show that for positive $a$  $$\int_{-\infty}^{\infty}{\frac{\cos(x)}{x^2+a^2}} dx = \frac{\pi e^{-a}}{a}$$  I'm not even sure how to define a smart contour… I guess it can't be a half circle, since $\cos(z)$ is unbounded for big imaginary parts. If I take a rectangle, then the vertical lines will have no impact in the limit since $\cos(z)$ is bounded there and $\frac{1}{z^2}$ decreases rapidly, but for the "way back" i can't find a good choice since the nominator isn't periodic… :(


Does "hearting" farm animals do anything?

The first time each day you right-click on farm animals you get a heart, like with your pet. Does this have any effect?  Particularly related to the 5 heart "progress bar" thing you get when you right-click them the next time. Or is that heart "progress bar" just something that grows as long as the animal has food?


which version of ubuntu runs on my laptop?

Configuration HP Pavilion g6-2338ee running Windows 8 64 bit Intel CORE i5 2.6 GHz RAM- 4GB HDD- 500GB Supports Direct X 11 Intel HD Graphics 4000


I am rather sure that I set up hibernation correctly, and that the swap file I am using is being recognized and written to when I click hibernate. (/hibernate.img) In the corner of the screen, it says system snapshot, compression ratio, etc.  However, when I resume from hibernate, the top left corner reads "resuming from hibernate.img" but then the system just freezes. Every time.  Some of the tutorials mentioned using a specially compiled kernel, and I have not done this. The kernel is simply 3.2.0-25-generic.  I am using 12.04 64-bit. Any help would be great.


I noticed that /var/spool/nullmailer directory contains a weird trigger entity which is displayed in yellow and has a “|” suffix.  It doesn't seem to be a directory (at least I can't cd into it), and when I try to open it with vi, the console freezes.  What is that thing?


Below is the code that I was trying to understand.  public static void main(String[] args) {     try     {         System.out.println(args[0]);     }     catch (ArrayIndexOutOfBoundsException e)     {         System.out.println("ArrayIndexOutOfBoundsException");         throw new NullPointerException();     }     catch (NullPointerException e)     {         System.out.println("NullPointerException");         throw new Exception();     }     catch (Exception e)     {         System.out.println("Exception");     } }   Everything is fine except when I am throwing new Exception();. So when I am doing so an error is occurring saying, "Unhandled exception type Exception" though I have provided the catch statement below to handle it.  So I know the solution to the problem but I want to know the reason. What are the insights that I am missing.   Can anybody explain it.


I'm new to JavaScript and I'm struggling to understand how function Person(age, name, gender) {     this.name = name;     this.age = age;     this.gender = gender; }  is any different than function Person(age, name, gender) {     name = this.name;     age = this.age;     gender = this.gender; }  Because with the first version of the code, everything runs smoothly and when I create var Bob = new Person(30, "Bob", "male");  and do this document.getElementById("demo").innerHTML = Bob.name;  it successfully prints "Bob". But when I run the second version of the code I get undefined. Why or how does it matter which side of the equal sign something is on?


`ccmp` in Lua（la)TeX/ConTeXt, with Source Han serif font

Google and Adobe released a new CJK font  recently. One of the amazing feature is that, using opentype ccmp feature, it becomes possible to type the chinese character biang, as described in  article. This character can be described using IDS as  ⿺辶⿳穴⿰月⿰⿲⿱幺长⿱言马⿱幺长刂心   I saw that LuaTeX seems to support the ccmp feature. I am wondering how can I type this character.  This question is for my curiosity and just for fun.


Functions that are sets of all function - proofs

I'm going through the book Proofs and fundamentals, by Bloch, and it doesn't include a solution manual for it's examples. It doesn't have many examples on notation and proof strategy for certain cases, so I needed a little help.    Although I understand the idea, and can draw it out, I'm not sure how to write it in decent proof notation. Any help would be appreciated!   Edit: apologies, my idea is this: theres some function in $F(C,A\times B)$ such that theres some $x$ within $C$ that means $g(x)$ is within $A\times B$. Similarly, the second two imply that for some function within $F(A,C)$ there exists a value $x$ such that $g(x)=C$. and similarly for the third part from $B\rightarrow C$. It's easy to see with drawing it out that these two are the same because one will have a part within A and the other will lead to a part within $B$, so their cross will be the same. I wanted to go about proving it by setting a function $f$ within $F(C,AxB)$ and then working from there, but I really have no idea where to start or the notation.


How to influence the position of float environments like figure and table in LaTeX?   This is a general question and should collect useful answers for all users. I hope we can use this as a reference


In my assignment I have to evaluate the (improper) integral, by means of the "comparison theorem". And note whether the function is divergent or convergent. $$\int^{\infty}_{0} \frac{x}{x^3 + 1}dx$$  The comparison theorem basically says     Suppose $f$ and $g$ are continuous functions with $f(x) \geq  (x)$ for $x \geq a$. Then:   A) if $\int^\infty_af(x)dx$ is convergent then $\int^\infty_ag(x)dx$ is convergent   B) if $\int^\infty_ag(x)dx$ is divergent then $\int^\infty_af(x)dx$ is divergent     So in other words: to prove if a given integral is convergent you find a function whose integral is larger than the given integral (within the boundaries). And to prove divergence you find a "divergent integral" whose function is always smaller than the function is question.  Now how should I go with this? Is there any trick to the above? Can I "see" (without calculator/automatic plotting) if an integral will be divergent or convergent (so to reduce time)?


So the first derivative w.r.t. t:  $\frac{dz}{dt} = \frac{\partial f}{\partial x} \times \frac{dx}{dt} +  \frac{\partial f}{\partial f} \times \frac{dy}{dt}$  How would I find the 2nd derivative?  EDIT:   In particular there is a term in when calculating the 2nd derivative :    $$ \frac {d}{dt} ( \frac {\partial f}{\partial x}) $$  It is calculating this step that  I do not understand  Thanks


What are the masters options available for getting into computer vision and image processing research from an electronics background?

Having done bachelors in electronics and instrumentation and a research experience in the field of image processing and computer vision and some publications in the same, what are the possible MS options where I can study computer vision and image processing? Can I opt for MS in robotics, computer science, signal processing?  My confusion is regarding the fact that I was a bachelors student in a different field. Would it be difficult for me to change to a masters program in this other field?


Is it possible to recursively instance object particles?

I have a seed object with some particle hair strands. I've specified this object to be instanced in another particle system, then specified that object to be instanced in yet another particle system.  To clarify:      I have a cube with hairs strands I have a Suzanne coated in cubes with hair strands (the hair strands only appear in the render, which is fine) I have another Suzanne coated in Suzannes, but these Suzannes don't have cubes or strands like I was hoping..     Is there a way to get the particle systems to keep recursing, so that the last Suzanne is coated in Suzannes coated in cubes coated in strands?


The double quotation used with the matched value with the parameter -name in find

Why the matched value with the parameter -name in find must be marked with double quotation?  # find / -type f -name *.out |wc -l 1>mv.out                                   0403-027 The parameter list is too long. # cat mv.out                                                           0 # find / -type f -name "*.out" |wc -l 1>mv.out                                    # cat mv.out                                                                                146302


Well I do know that they sometimes fall as rain, but my question is why don't the droplets fall as soon as they condense from steam to cloud.  Clouds are white by the process of Mie scattering so the particles are on the order of light wavelength ~$0.5 \mu m$, although small would a particle of this size not slowly fall to the ground?  When a cloud does rain many of the rain drops fall at the same time what is physically happening to the droplets to encourage them to join into large drops that fall?


Service --status-all --> what does the column with [ ? ],[ + ], and [ - ] mean?

If I run the command "service --status-all", each (running?) service is listed in column format. The first column has either a [ ? ], [ + ], or [ - ] before the service name. What does this column represent? What does ?, +, and - mean?   Sorry if this is a simple question. I searched online for ~30 minutes before just coming here and asking.  I even found this:  where the "correct" answer states "It draws a [ + ] or [ - ] depending on whether the exit status was zero or nonzero, respectively.".  So, I guess my new question is what does status zero and nonzero(!?!?!) mean?


how find the nearest iframes with ffprobe?

I wonder if can find the nearest iframes from certain position(might be certain seconds) in Video file with ffprobe or ffmpeg.  Is it possible? The result what I want is seconds unit position of frames.  My command is ffprobe -show_frames -select_streams v -print_format json=c=1 Z63902_5_130719.ts | grep "I" | grep "\"pkt_dts_time\"". Since there is only a capital 'I' in that json, I grep only "I". My problem is that this is too slow. My final goal is get iframe positions from RTSP protocol and make list. If it goes to RTSP, it will be much slower than now.  How can I solve this?


The question seems rather simple, yet it is suprisingly difficult.   There is a bug under one of six tiles and it is my job to find it. The tiles lie in a row. At night, the bug moves randomly 1 tile, so it either moves to the left or to the right. During the day you are allowed to pick up one tile to see if the bug is there. If you choose the tiles as optimal as possible, how many days will it take you to find the bug, at most?   The answer is multiple choice, namely a.) 6 days, b.) 8 days or c.) 10 days.   Lets defne the tiles as follows: the first tile on the left we call 1, then the tile on the right of the first tile we call 2, etc. until we have a set {1,2,3,4,5,6}.   MY APPROACH: [I was thinking that you start with 3. You find that it's not there, but the bug could have been under 4 and moved during the night under 3, so the next day you lift 3 again. It's not there, but the bug could have gone from 5 to 4 and now there is again a possibility that the bug moves under 3 when you decide to lift another tile, so again you would think it's best to lift 3. Since the bug can move between 5 and 6 back and forth it is useless to continue looking under just tile 3. But if you decide to look under another tile there is always the possibility that the bug will move under the tile you looked under one days before that. Therefore, it seems to me that the problem is unsolvable.   I tried to visualize the problem on a lattice of 10 by 6 where every day (the number of rows) is representated by a row of 6 tiles. Then drawing two lines from every tile in the first row to the left and right tile in the row below and leaving out the lines from the tile I looked under. Then I eliminated the tiles to which the most lines come to. But after 10 days there are about 4/5 lines per tile, so this doesn't work even though it seems rock solid to me.]  Does anybody have any suggestions or solutions?


Identity Value returned as 0 using SCOPE_IDENTITY()

I have a contact info form in Visual Studio (using C#) that can be used to turn the contact into a customer, to do so I want to send the id from the contact that was just created to the other form and to do this I created a stored procedure that returns the id using SCOPE_IDENTITY(). It works in SQL Server and returns the identity correctly but when I try to aquire it, convert the int into string and set it in a label for testing it reads as 0.  My stored procedure is as follows.  SET ANSI_NULLS ON GO SET QUOTED_IDENTIFIER ON GO  CREATE PROCEDURE IdentityTest       @FirstName varchar(50),       @LastName varchar(50),       @id int output AS BEGIN       SET NOCOUNT ON;        INSERT INTO Employees (FirstName, LastName)       VALUES (@FirstName, @LastName)        SET @id = SCOPE_IDENTITY()       RETURN  @id END   In my form.aspx.cs I have the following code to acess the DB.  protected void Button1_Click(object sender, EventArgs e) {      SqlCommand cons = new SqlCommand("IdentityTest", cncon);      cons.CommandType = CommandType.StoredProcedure;       cons.Parameters.Add("@FirstName", SqlDbType.NVarChar);      cons.Parameters.Add("@LastName", SqlDbType.NVarChar);      cons.Parameters.Add("@id", SqlDbType.Int);       cons.Parameters["@FirstName"].Value = nom.Value;      cons.Parameters["@LastName"].Value = dirclie.Value;      cons.Parameters["@id"].Value = IdCliente;       string IdClientesString = IdCliente.ToString();       cncon.Open();      cons.ExecuteNonQuery();       Label1.Text = IdClientesString;      cncon.Close(); }


Operand should contain 1 column(s) in java

String  sql = "SELECT (Employee_name, Password) FROM employee WHERE (Employee_name = '"+name+"'  AND Password = '"+password+"')";   and getting the following exception in JSP java.sql.sqlexception insert operand should contain 1 column(s)  Please help.


From where term $\left(\frac{1}{n}+\frac{1}{m}\right)$ came in estimated variance of $\bar x - \bar y$

I encountered such a formula for pooled variance:  $$\frac{(n-1)s_x^2+(m-1)s_y^2}{n+m-2}\left(\frac{1}{n} + \frac{1}{m}\right)$$  Here we have two samples of the following sizes $n$ and $m$. $s_x, s_y$ are the sample variances.  I understand that the first term is a weighted average, but from the second term comes?


Most general form of motion where period is amplitude independent

Is there another type of motion other than SHM that has this property? How would one systematically find the general form of the motion that respects this constraint?


I have noticed that when I'm using the Stack Overflow mobile website, it is impossible to tap number of votes to get more details about it (upvotes & downvotes).  I don't know if this feature is not implemented, or the size of votes count element is too small to be tapped.


simply connected subset of $\mathbb R^2$ contractible?

I know that every simply connected open subset of $\mathbb R^2$ is homeomorphic with $\mathbb R^2$ . My question is : Is every simply connected subset of $\mathbb R^2$ contractible ?  Remark : By simply connected I mean path connected with trivial fundamental group .


Why do the rationals, integers and naturals all have the same cardinality?

So I answered this question:  I believe my answer is correct, however one thing I couldn't explain fully, and which is bugging me, is why the rationals $\mathbb Q$, integers $\mathbb Z$ and naturals $\mathbb N$ all have cardinality $| \mathbb Q |=| \mathbb Z | = |\mathbb N| = \aleph_0$, when $\mathbb N \subsetneq \mathbb Z \subsetneq \mathbb Q$.  The basic proof of the other question, from my answer, is that for any $r$ in $\mathbb Q$ there is a single function $f(r)$ such that $f(r) \in \mathbb Z$, and the same holds between $\mathbb Z$ and $\mathbb N$. Because there is this 1:1 transformation possible, there must be the same number of numbers in the three sets, because otherwise there would be a number in one set for which the bijection could not produce a number of the other set, and this is not so.  Now, Belgi explained why $1<2$ in the other question by defining the value 0 as the cardinality of the empty set $\emptyset$, 1 as the cardinality of a set of sets containing only the empty set, and 2 as the set of sets containing the empty set and a set containing the empty set, then proceeding as follows:     Now that we have defined the natural numbers we can define when one number   is smaller than another. The definition is $x<y$ is $x\subset y$   and $x\neq y$ .      Clearly $\{\emptyset\}\neq\{\emptyset,\{\emptyset\}\}$ and $\{\emptyset\}\subset\neq\{\emptyset,\{\emptyset\}\}$   So this a proof, by definition, of why $1<2$.   ... however, by the same definition, because $\mathbb N \subsetneq \mathbb Z \subsetneq \mathbb Q$, then $| \mathbb N | < | \mathbb Z | < |\mathbb Q|$ and thus a maximum of one of these quantities can be the ordinal quantity $\aleph_0$.


I installed NTP server on Ubuntu Server 10.04 using:  sudo apt-get install ntp   The NTP daemon seems working and listening on the 123 port.  However, I was not able to get the time from another machine:  sudo ntpdate -u my_ntp_server 23 Nov 18:48:41 ntpdate[2990]: no server suitable for synchronization found   Is there any necessary configurations to do?


What do you call the phenomenon where a rectangle □ is shown because a font lacks a glyph?

Is there a name to describe the situation where a particular  is shown on a computer screen in a particular , but this font does not have a  for this particular character?  Usually, the result looks like this: □    A kind of empty rectangle. Sometimes it shows the code for that character within the rectangle.    What do yo call this phenomenon?  If there is no name, is there a common term referring to this "rectangle"?  Some Japanese people call this "tofubake" because rectangles look like .  (It is not . Mojibake happens when  meta-information is lost. It is not the problem here. Using a better font solves this phenomenon, but does not solve mojibake. Selecting a character encoding solves mojibake, but does not solve this phenomenon.)


My friend is asking about this icon on the notification bar. Is it from a application or just find in page?


thawing and cooking frozen raw chicken backs

I purchased a case of raw chicken back bones. Cleaned, portioned into 4 lb sealed bags and frozen.  I bought them to make batches of bone broth.  When I unthaw a bag in my refrigerator I notice a lot of blood. Is it safe to put all of that blood/juice and bone parts - covered with water into my crock pot to cook up slow for 12 hours?


I am trying to align the columns of multiple tables.  I know I can use p column format to fix column widths but I would prefer that TeX automatically figure out the widths for me.  I was hoping to:    output one table with all rows of each subsequent table so that the column widths of the combined table would be automatically good for all the subsequent tables  then output each subsequent table using the same settings and  figure out some way in which the first combined table could be generated but not visible.   Here is my attempt.  The first combined table uses \savetabu to save the settings and then each subsequent table uses \usetabu to retrieve them.  Unfortunately this does not work as I had hoped.  The columns do not line up as the output below (after the code) shows. Does anyone have a method of accomplishing this?  \documentclass{article}  \usepackage{tabu} \begin{document}  Output both tables together as one table and then output each individual table.  We had hoped that this would cause the subsequent tables to be the same width as the first since the first contains all columns of the subsequent tables but it seems that that does not work.  \begin{center} \begin{tabu}{ll}\savetabu{mytabu2} 1 & 2 \\ 3 & 4 \\ abcdefghijklmnopqrstuvwxyz & 10 \\ 5 & 6 \\ \end{tabu} \end{center}  \begin{center} \begin{tabu}{\usetabu{mytabu2}} 1 & 2 \\ 3 & 4 \\ \end{tabu} \end{center}  \begin{center} \begin{tabu}{\usetabu{mytabu2}} abcdefghijklmnopqrstuvwxyz & 10 \\ 5 & 6 \\ \end{tabu} \end{center}  \end{document}   Here is the output:


Is there any true inertial reference frame in the universe?

Is there any true  in the universe?  Newton's first law states that an object at rest remains at rest, and an object performing uniform motion performs uniform motion, until and unless acted upon by an external force, if viewed from an inertial frame. It is the definition of an inertial frame of reference. And Newton's second law states that the net external force acting on a particle equals its mass times its acceleration. Thus we need to have an inertial frame in order for Newton's 1st and 2nd laws to be applicable.  Scientists claim that Earth is an inertial frame, either the  frame or the  frame.  Why is that? Earth's different parts have different accelerations when it performs rotational motion about its axis. Now you may say that Earth's axis is inertial, but the Earth is also revolving around the Sun. Thus Earth's frame should be non-inertial.  Even supposing that earth's frame is inertial, then it means that rest of the universe is non-inertial, because only a frame that moves with constant velocity with respect to an inertial frame is also an inertial frame and according to various scientific experiments there is no other matter in this universe which satisfies that criterion. Now you may say that earth is an approximate inertial frame, but still, my question is: is there any perfect inertial frame in the universe where Newton's laws are exactly applicable?


Is there any  site where I can ask about website security? I'm looking for a site that can help my job, currently as a Web Tester.


How could I convert a Unicode String input to a hex value in python?

I have a input JSON file which include data with String like "Address": "0x33". I would like to use this data to open my raw data file and seek to the file location.   infile.seek(0x30,0)   How could I convert the input data to a hex value and let my seeking address flexiable?  address="0x30" infile.seek(address,0)   How to convert string "0x30" to a hex value 0x30?


QGIS - Determine percentage of coverage of buffer for census tracts

I have a census tract shapefile for the state of South Dakota. I have providers plotted with a 40 mile radius buffer. I am trying to determine what percent of each census tract is covered by any part of the buffer. How can I do this?


Schengen visa expired, best way to exit EU for going to Russia

I am from Philippines. I have worked in Moscow before with a working visa for 3 years and it is still good until August 2017.  My story is I went to Italy with my employer because I moved there for work. We made the paper and I received just a tourist visa for 3 months (90 days) but when we arrived there we try to do all for make more time in my visa for stay but we lose time because some people say "don't worry we will do for you" until the day of expiration and then did nothing.  Now I am illegal there and I really want to make legal my paper because my employer can move again country (he try all for make my paper but he is not Italian either).  I think I don't have solution to wait for the news amnesty but I don't know when.  My last solution is to go back to Moscow because I have some contact in the embassy and they can make for me a new Schengen but they told me that if I use airplane it's 99% sure that I will be banned and fined.  My questions is if I use train and I have a ticket, will they ask to see my Italian visa ? Or if they normally just ask for the ticket and sometimes the passport to see the same name ? Because after when I will arrive in Russia I will have my paper legal, and also if they ask me where did you go I will say Moscow I think they will check the most important the visa for Russia.  I have a 3 choices of way by train if you can help me for some country more easy :    choice 1 : Italy, Liechtenstein, Germany, Poland, Belarus, Russia  choice 2: Same just I need to use a postbus in Germany in Bayreuth-Berlin   choice 3: Italy, Austria, Czech Republic, Poland, Belarus, Russia


Is there a word for the definition of an acronym?

I can describe "IMHO" as an acronym for "in my humble opinion."  How can I describe the reverse processes of translating the acronym into the actual phrase?  That is to say, if "IMHO" is the acronym, what do we call "in my humble opinion"?


Does a log transform always bring a distribution closer to normal?

I have a highly right skewed data set with a large range of values (from 1 ~ 10^6) (can't share the actual data for work related reasons).   When I plot the log of the data instead, the distribution looks a lot more like a normal distribution.   Have I stumbled on a meaningful insight in the data set, or is just a general property of the log transform that it brings the distribution closer to normal?


Shutdown does not clean the state of the drive

I was not sure whether to ask this in superuser or here. Anyway, I have dual boot: Win 8 and Ubuntu 14.04 and 3 disk drives:   for Windows OS (the famous C://) neutral one, for files (lets call it "D drive") for Linux (Ubuntu is installed solely on this one)   When I restart from Windows and go in Linux, I can open D drive, but if I shutdown from Windows - I cannot open D drive in Linux. It gives me an error saying that the drive is in an unsafe state - the same as if I hibernate from Windows. The hibernation I understand why, but isn't the shutdown supposed to clear the state of the drive (as the restart does)?


Calculate distance between two latitude-longitude points? (Haversine formula)

How do I calculate the distance between two points specified by latitude and longitude?  For clarification, I'd like the distance in kilometers; the points use the WGS84 system and I'd like to understand the relative accuracies of the approaches available.


when I update using apt-get update on Beaglebone black, I got the following error,  W: GPG error: http://repos.rcn-ee.net trusty InRelease: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY D284E608A4C46402   I've tried following command given in some forum  $ apt-key adv --keyserver keyserver.ubuntu.com --recv-key D284E608A4C46402 Executing: gpg --ignore-time-conflict --no-options --no-default-keyring --homedir /tmp/tmp.YlaPkjE1g4 --no-auto-check-trustdb --trust-model always --keyring /etc/apt/trusted.gpg --primary-keyring /etc/apt/trusted.gpg --keyserver keyserver.ubuntu.com --recv-key D284E608A4C46402 gpg: requesting key A4C46402 from hkp server keyserver.ubuntu.com gpgkeys: key D284E608A4C46402 not found on keyserver gpg: no valid OpenPGP data found. gpg: Total number processed: 0   and I've tried  $ gpg --keyserver keyserver.ubuntu.com --recv-key D284E608A4C46402' gpg: requesting key A4C46402 from hkp server keyserver.ubuntu.com gpgkeys: key D284E608A4C46402 not found on keyserver gpg: no valid OpenPGP data found. gpg: Total number processed: 0  $ gpg -a --export D284E608A4C46402 | sudo apt-key add - gpg: WARNING: nothing exported gpg: no valid OpenPGP data found   I'm behind proxy, and configured /etc/apt/apt.conf and /etc/environment files and aswell exported the proxy setting in terminal, pinging any site from terminal is working.   and still I get the GPG error same as above, can anyone suggest me a solution?


Consider the eight objects $\pm 1, \pm i, \pm j, \pm k$ with multiplication rules:   $ij=k,jk=i,ki=j,ji=-k,kj=-i,ik=-j,i^2=j^2=k^2=-1$,   where the minus signs behave as expected and $1$ and $-1$ multiply as expected. Show that these objects form a group containing exactly one involution.  Well, it is easy to determine closure from the definition. $1$ is clearly the identity, and the inverses can also be determined $(i,-i),(j,-j),(k,-k)$, $-1$ with itself, and $1$ with itself. The only involution is $-1$. Is there an easy way to check associativity of this group? There are too many possible combinations $(ab)c=a(bc)$ to check directly. ($8^3$ possible combinations)


"Unable to Process Request Concurrent requests limit exceeded". Is there a way how can I overcome this error?

I have a scenario where an external system calls the SOAP webservice inside salesforce and it causes "Unable to Process Request Concurrent requests limit exceeded". Any thoughts or workaround to get rid of this error?


Which Stack Exchange site for a question about mobile cloud backend solutions and licensing

I want to ask a question on Mobile Cloud backend solutions and mobile app licensing. I've tried Stack Overflow and Super User and the questions have been closed. Please can you tell me which site is best for these?


I have asked to replace so many SSD I don't feel like asking it again. But if the SSD is indeed broken, just one time server down will cost me $500 or something.  So, how do I make sure that the SSD is indeed broken?  Can I just reformat hard disk like in windows? The disk is mounted.  Before a loose pin make the server reboot too many times. It seems that it damaged all SSD there.  /bin/ls: cannot access cache-zch-5666-cache.txt: Input/output error /bin/ls: cannot access cache-zch-4970-cache.txt: Input/output error /bin/ls: cannot access cache-zch-4782-cache.txt: Input/output error ./   cache-zch-4782-cache.txt  cache-zch-5666-cache.txt ../  cache-zch-4970-cache.txt root@host [/home2/investgr1/public_html/hello/cache/zch]# rm * rm: cannot remove `cache-zch-4782-cache.txt': Input/output error rm: cannot remove `cache-zch-4970-cache.txt': Input/output error rm: cannot remove `cache-zch-5666-cache.txt': Input/output error root@host [/home2/investgr1/public_html/hello/cache/zch]#


How to use possessives when the subject has a number after?

I have a question about possessives.  While "Peter's ball" is easy and clear.  How do I express the notion of "the ball that belongs to agent 2"?  Would it be "agent's 2 ball" or "agent 2's ball" or what else?


A derangement of a set $A$ is a bijection from $A$ to itself with no fixed points. Is it the case that every infinite set has a derangement?


Is GLM appropriate for an extreme unbalanced dataset?

I have a dataset with 174 females and 28 males. I am interested in the gender differences, as well as the interactions between gender and other factors, in a continuous dependent variable. Is GLM appropriate for this very unbalanced dataset? What would be a better alternative?


Changing value in list of list python. Why does it change whole row?


Following on from my previous question, , I have now come across a problem regarding the timezone, and it turns out that it's not always going to be "+0200". So when strptime tries to parse it as such, it throws up an exception.  I thought about just chopping off the +0200 with [:-6] or whatever, but is there a real way to do this with strptime?  I am using Python 2.5.2 if it matters.  >>> from datetime import datetime >>> fmt = "%a, %d %b %Y %H:%M:%S +0200" >>> datetime.strptime("Tue, 22 Jul 2008 08:17:41 +0200", fmt) datetime.datetime(2008, 7, 22, 8, 17, 41) >>> datetime.strptime("Tue, 22 Jul 2008 08:17:41 +0300", fmt) Traceback (most recent call last):   File "<stdin>", line 1, in <module>   File "/usr/lib/python2.5/_strptime.py", line 330, in strptime     (data_string, format)) ValueError: time data did not match format:  data=Tue, 22 Jul 2008 08:17:41 +0300  fmt=%a, %d %b %Y %H:%M:%S +0200


My 7 year old son acts out in sexual ways

I'm a single mother of 2. My daughter is 13 and my son is 7. My son's father shot himself 2 years ago. That's when things started to change. When his dad was alive, my son never wanted to go to his house. He would scream and cry and latch on to me. So I would keep him with me. I know his dad watched a lot of porn. And I'm wondering if he saw it.  At first I thought, "They're kids, and kids experiment." (I know I did when I was little.) In the past 2 years my niece and my son have been caught together more than a few times, and each time I would talk to them about it.   My son has been caught with his pants down and my 5-year-old niece sucking his penis. I instantly told them to stop. I explained that kids don't do stuff like that. I told them it was disgusting and they should never touch each other again. I talked to my niece about it and she said he told her to do it. It happened a couple other times except it got worse. He tried to stick his penis in her vagina. They are no longer allowed to be around each other. And my son isn't going to be around any other kids until I find out what is going on.   I'm just not sure why this is happening. I'm so scared he's going to be a bad person. I want to help him. When I talk to him about it he says, "I don't know, mom," and then changes the subject.  How can I help my child?


Can arbitrary matrices be decomposed using the Pauli basis?

Is it possible to decompose a hermitian and unitrary matrix $A$ into the sum of the Pauli matrix Kronecker products?   For example, I have a matrix 16x16 and want it to be decomposed into something like $$A =\sum_{i,j,k,l}h_{ijkl}\sigma_i\otimes\sigma_j\otimes\sigma_k\otimes\sigma_l$$ I can't find any clear explanation how it can be done. I found only this for two-dimentional case:


What is the mass of Photon or Light Particle?

We know that any particle moving at speed of light will have infinite mass.  Since even Light has particles. Then what is the size of the Particle? How to imagine this with the mass of light particles.


Why is the definite article used here but not here?

Why do I (a non-expert native English speaker) include the definite article here before the country?  Here's a delivery. It's destined for the US. Here's a delivery. It's destined for the UK. Here's a delivery. It's destined for the Republic of Korea. Here's a delivery. It's destined for the Republic of Ireland.   And not here?  Here's a delivery. It's destined for Ireland Here's a delivery. It's destined for Portugal. Here's a delivery. It's destined for Germany. Here's a delivery. It's destined for Western Samoa.


Can you name this sci fi film that is similar to The Matrix?

In this movie there are scientists who (spoilers ahead)       ...are creating a simulation. One scientist starts seeing odd looking characters but no one else sees them. He asks around and more and more characters are missing or don't know about the characters in the story he knows about.  He finds out that he is part of a simulation. He finds out that the characters only he remembers have been deleted. He also finds out that there are characters from his own simulation that have broken free of his simulation and are in his world.    Hints: I remember this being an older film (70's?); it might have been foreign film possibly with subtitles (not Hollywood); it might have been part of the Criterion collection; I'm pretty sure I streamed it from Hulu. Sorry, I can't remember more details.


Does downing a character at the start of its turn require an immediate Death Saving Throw?

Say a Player Character (PC) with low HP is in a Cloudkill:     When a creature enters the spell's area for the first time on a turn or starts its turn there, that creature must make a Constitution saving throw. The creature takes 5d8 poison damage on a failed save, or half as much damage on a successful one.      The PC is next in initiative and starts their turn. The only effect to resolve is the Cloudkill. It fails the save and the resulting damage is sufficient to get them to 0 HP.  Since this event occurred "at the start of the turn" and this is also when Death Saving Throws happen for a downed character, does the PC need to make an immediate Death Saving Throw, or, did has the "start of the turn" passed and the first Death Saving Throw will be rolled at the start next of the round?  I am aware of this relevant question "" and the accepted answer: events occurring at start of turn are resolved in the order chosen by the player.     However, since in my example the events cannot be reversed (the PC cannot make a Death Saving Throw before taking the damage), I feel that the question stands on its own.  The question is also not a duplicate of  because the latter is asking for a PC that is already down.   I am asking for the specific instance of the turn where the PC falls unconscious due to a "start of the turn" trigger.


As far as I understand it, quantum mechanics only predicts the probabilities of finding a system in some state of some observable when we make a measurement.   So, what exactly constitutes a measurement that will make the system to collapse?


Error connecting to mysql fabric via python script

I have three VMs running on Windows Azure. Two VMs running mysql database, the third VM running mysql fabric node. When I tried to use python connector to connect to fabric node, this problem happens: mysql.connector.errors.InterfaceError: Connection with Fabric failed: <urlopen error [Errno 111] Connection refused> I'm wondering what causes this problem.   I used this command to setup fabric environment:  mysqlfabric manage setup --param=storage.user=fabric_store --param=storage.password=password --config=/etc/mysql/fabric.cfg   python script:  import mysql.connector from mysql.connector import fabric     cnx = mysql.connector.connect(             fabric={             "host" : "myfabricnode.com",             "port" : 32274,             "username" : "admin",             "password" : "secret"                            }             )   fabric.cfg:  [DEFAULT] prefix = sysconfdir = /etc logdir = /var/log  [storage] address = localhost:3307 user = fabric_store password = password database = mysql_fabric auth_plugin = mysql_native_password connection_timeout = 6 connection_attempts = 6 connection_delay = 1  [servers] user = fabric_server password = password backup_user = fabric_backup backup_password = password restore_user = fabric_restore restore_password = password unreachable_timeout = 5  [protocol.xmlrpc] #address = myfabricnode.com:32274 address = localhost:32274 threads = 5 user = admin password = secret disable_authentication = no realm = MySQL Fabric ssl_ca =  ssl_cert =  ssl_key =   [protocol.mysql] #address = myfabricnode.com:32275 address = localhost:32275 user = admin password = secret disable_authentication = no ssl_ca =  ssl_cert =  ssl_key =   [executor] executors = 5  [logging] #level = INFO level = DEBUG #url = /home/tester/fabric.log url = file:///var/log/fabric.log  [sharding] mysqldump_program = /usr/bin/mysqldump mysqlclient_program = /usr/bin/mysql prune_limit = 10000  [statistics] prune_time = 3600  [failure_tracking] notifications = 300 notification_clients = 50 notification_interval = 60 failover_interval = 0 detections = 3 detection_interval = 6 detection_timeout = 1 prune_time = 3600  [connector] ttl = 1   BTW, I've opened the endpoint 32274 & 32275 on the fabric node(myfabricnode.con), but I can't telnet the 32274 port from the remote server, I also tried to use the private ip address and public ip address in fabric.cfg, but I still got the same error.   Can anyone help me with that?


what are the failure cases of Newton Raphson Method?

I want list of failure cases for Newton-Raphson method. If possible please provide flow chart for Newton-Raphson method.


Why does a floating object displace more substance than a sunk object?

Consider a box floating on water having a coin on top, now suppose after some time by some external influence, the coin is dropped into water. After doing the calculations, to my surprise, I found that the water level actually drops...I just can't understand this phenomena. For what reason does this happen? I think that my whole conception of buoyancy is wrong after this because intuitively I think water level rises because the coin would apply both it's weight and take up some volume while in the water.   Notes for future answers/ existing answers:  After some deep thinking, I started to realize the problem was that I had this intuition that water would have been compressed by the weight somehow. How exactly does that effect vary in the scenario displayed above? After even more deep thinking, how does the behaviour of fluid change as we relax/ impose the condition of compressibility ? specifically how would results in this case differ? ( A diagram would be nice) Suppose we constantly applied a force onto the surface of a water, like a pressure, by the logic given in most answers, the water level should rise! but, intuitively it is often said that water level drops as we apply more pressure on the face open to atmosphere   My question is different  because my confusion is mostly about the actual structure of the fluid and response of fluids to load rather than the directly calculated volume changes.


Why does “klick” mean kilometer in US military slang?

Wiktionary says it is either likely a pseudo-condensed pronunciation of kilometer or onomatopoeic of the sound of a military odometer.     Though kilometers are not commonly used to measure distance in the USA, “klick” is commonly used by the US military, which uses the metric system almost exclusively in order to facilitate communication with allied forces.   Here’s an example of the word being used in the film Apocalypse Now:     We’re going up river about 75 klicks above the Do Lung bridge.


I have an updated TeX Live distribution. Following  I copied the code exactly: \documentclass{article} \usepackage{fontspec} \defaultfontfeatures{Ligatures=TeX}           \newcommand\test[1]{%   #1\\{\fontspec{#1}Βίβλος γενέσεως Ἰησοῦ Χριστοῦ υἱοῦ Δαυὶδ υἱοῦ Ἀβραάμ.}   \par\medskip}      \setlength{\parindent}{0pt}      \begin{document}      \test{CMU Serif} \test{EB Garamond} \test{GFS Artemisia} \test{GFS Baskerville} \test{GFS Bodoni} \test{GFS Complutum} \test{GFS Didot} \test{GFS Olga} \test{GFS Porson} \test{GFS Solomos} \test{Junicode} \test{Linux Libertine O} \test{Old Standard} \end{document}  into c.tex and then did xelatex c. This returned the following error:  /usr/local/texlive/2013/texmf-dist/tex/latex/tipa/t3cmr.fd)kpathsea:make_tex: Invalid fontname `CMU Serif', contains ' ' fontspec error: "font-not-found"  l.14 \test{CMU Serif}  Thus its first objection is to a space in a font name. How can that linked example work with a whole list of fonts with spaces in their names? And it also appears that no font whose name contains the strings "Serif" and "CMU" is part of TeX Live 2013:  find /usr/local/texlive -type f | egrep -i  serif | egrep -i cmu  What am I missing?


Good undergraduate level textbook on elliptic curves

I'm taking a Elliptic Curves class as an undergraduate math major. We are using "Ellpitic Curves" by  Lawrence C. Washington.  I'm struggling and would like some other resources I could use to help supplement my study. I ordered "Rational Points on Elliptic Curves" by Silverman and Tate.  Ive done some searching but most of the recommendations ive found are more advanced and I think would be over my head. Is there anything else I could potentially get something out of? Many thanks


I'm very new to ubuntu so I'm still very much stumbling around. In the file drawer I can see an icon for my network drive but I cant figure out where I enter or store the user id and password that this network drive has on it. The network drive is a windows based device  Thanks in advance.


I want to time a command which consists of two separate commands with one piping output to another. For example, consider the two scripts below:  $ cat foo.sh #!/bin/sh sleep 4  $ cat bar.sh #!/bin/sh sleep 2   Now, how can I get time to report the time taken by foo.sh | bar.sh (and yes, I know the pipe makes no sense here, but this is just an example)? It does work as expected if I run them sequentially in a subshell without piping:  $ time ( foo.sh; bar.sh )  real    0m6.020s user    0m0.010s sys     0m0.003s   But I can't get it to work when piping:  $ time ( foo.sh | bar.sh )  real    0m4.009s user    0m0.007s sys     0m0.003s  $ time ( { foo.sh | bar.sh; } )  real    0m4.008s user    0m0.007s sys     0m0.000s  $ time sh -c "foo.sh | bar.sh "  real    0m4.006s user    0m0.000s sys     0m0.000s   I've read through a similar question () and also tried the standalone time executable:  $ /usr/bin/time -p sh -c "foo.sh | bar.sh" real 4.01 user 0.00 sys 0.00   It doesn't even work if I create a third script which only runs the pipe:  $ cat baz.sh #!/bin/sh foo.sh | bar.sh   And then time that:  $ time baz.sh  real    0m4.009s user    0m0.003s sys     0m0.000s   Interestingly, it doesn't appear as though time exits as soon as the first command is done. If I change bar.sh to:  #!/bin/sh sleep 2 seq 1 5   And then time again, I was expecting the time output to be printed before the seq but it isn't:  $ time ( { foo.sh | bar.sh; } ) 1 2 3 4 5  real    0m4.005s user    0m0.003s sys     0m0.000s   Looks like time doesn't count the time it took to execute bar.sh despite waiting for it to finish before printing its report1.  All tests were run on an Arch system and using bash 4.4.12(1)-release. I can only use bash for the project this is a part of so even if zsh or some other powerful shell can get around it, that won't be a viable solution for me.  So, how can I get the time a set of piped commands took to run? And, while we're at it, why doesn't it work? It looks like time immediately exits as soon as the first command has finished. Why?   I know I can get the individual times with something like this:  ( time foo.sh ) 2>foo.time | ( time bar.sh ) 2> bar.time   But I still would like to know if it's possible to time the whole thing as a single operation.     1 This doesn't seem to be a buffer issue, I tried running the scripts with unbuffered and stdbuf -i0 -o0 -e0 and the numbers were still printed before the time output.


I am struggling to understand the term static means and how it works. here I initialized a static variable "float percentage". and I have to convert it to percentage using convertToPercent() and after converting it I have to take the value and put the value to someMethod ()  to do some calculations  below is what I have   .h  class Foo     {  private:     static float percentage;  public :         float convertToPercent();  };   .cpp  float Foo::convertToPercent() {              percentage = (30/100) * 100;           return percentage; }  static float someMethod () {   //place the static percentage value here after doing convertToPercent() method to do some calculation; }   however it throws me an error message   Undefined symbols for architecture x86_64: "Foo::percentage", referenced from:  Foo::convertToPercent() in Foo.o   Apperciate for help given. thanks


Don't show pending suggested edits to me after I run out of votes

Now that I've reached 2k on Stack Overflow, I get access to the "Suggested Edits" review queue.  Although I only have 20 edits per day, the "suggested edit awaiting" icon in the top bar is always there and it bothers me a lot!  My suggestion is to apply one of three solutions:   Remove the suggested edits icon when we reach the maximum (50) edits Remove the Highlight (orange) on the suggested edits Remove the suggested edits part when we click on it   What do you think?


Prove that for all $U\subseteq A$ and $V\subseteq A$, that $f(U\cup V)=f(U)\cup f(V)$.  Hello everyone, I am having some trouble trying to prove this problem. Could I get some hints on starting the proof? Thank you.


Manuscript went from 'awaiting referee selection' to 'awaiting decision'. What does this mean?

I wonder if anyone has any answers to this? I am quite worried! I submitted my manuscript to a top international relations journal and it went through the usual admin checks and one day went to 'awaiting referee selection'. The next day it went to 'awaiting decision'!  I wonder if they made an error and decided to now make an editorial decision instead of sending it out for review? It seems to have skipped 'awaiting referee assignment' -> 'awaiting referee scores'.  Any info would be most helpful! Thank you!


Refugee in France, travelling to the USA as a tourist?

I am a refugee in France with a French travel passport. I want to visit the USA as a tourist. I don't know how to start. Should I take an interview appointment at the US embassy in France? Maybe I can do the ESTA visa electronically and buy my tickets?


Hostname conflict between system hostname and apache2 vHost

I own a server under Ubuntu 16 on my LAN where I run a Apache2 with many vHost websites.  One thing bothers me : The hostname of the server is the one from a vHost instead of the one written in the /etc/hostname file.  Any idea on how to fix this?  I have already edited the hostname and hosts files, run hostnamectl and restarted the system but it's still giving me the name from a vHost instead of giving me the name I want.  The name was shown in the motd for "last login from" when I used the server to connect to another one throught ssh and it show in Hostname part when I run a "Angry Ip Scanner" (a nMap equivalent).


How to show directories before files in Finder?

I would like to have windows in the Finder sort directories before files, in the manner of Microsoft Windows' Explorer as well as Linux KDE.  I tried following  but it did not yield the desired outcome, specifically some directories had contents sorted that way but some had files first then directories and some were still mixed.  Also, I would like to know what the difference is between sorting and arranging in the Show View Options screen.


There is no one guide that I have tried that results in a fully working WebEx on Linux. Typically audio is the feature hardest to get working. How do I get WebEx working with audio on Ubuntu?


How to dress suitably for Jungfrau mountain sightseeing trip?

I have planned to travel sightseeing at Jungfrau mountain in Switzerland.  Since I have checked with many weather forecast website on my trip date, they said the weather probably be cloudy, partly sunny and the temperature is about -5 °C.  I came from the warm climate (always hot) country, Thailand. So, I am not sure about how to dress suitably for the weather like this.  So, I would like to ask the suggestion for the way of dressing. Moreover, Do I need to bring any medicine to prevent or cure in some case?


Unity Third Person Controller Camera-Relative Script

I'm an newbie in game developing. So i have a script for a camera that i attach to the player. I was wondering how to make a Third Person Controller with WASD controls that moves in the direction that the camera is facing. If you need it here's the camera script that i use      using System.Collections; using System.Collections.Generic; using UnityEngine;  public class ThirdPersonCamera : MonoBehaviour {     //define some constants     private const float LOW_LIMIT = 0.0f;     private const float HIGH_LIMIT = 85.0f;      //these will be available in the editor     public GameObject theCamera;     public float followDistance = 5.0f;     public float mouseSensitivityX = 4.0f;     public float mouseSensitivityY = 2.0f;     public float heightOffset = 0.5f;      //private variables are hidden in editor     private bool isPaused = false;      // Use this for initialization     void Start () {         //place the camera and set the forward vector to match player         theCamera.transform.forward = gameObject.transform.forward;         //hide the cursor and lock the cursor to center         Cursor.visible = false;         Cursor.lockState = CursorLockMode.Locked;     }      // Update is called once per frame     void Update () {         //if escape key (default) is pressed, pause the game (feel free to change this)         if (Input.GetButton("Cancel"))         {             //flip the isPaused state, hide/unhide the cursor, flip the lock state             isPaused = !isPaused;             Cursor.visible = !Cursor.visible;             Cursor.lockState = Cursor.lockState == CursorLockMode.Locked ?             CursorLockMode.None : CursorLockMode.Locked;             System.Threading.Thread.Sleep(200);         }          if(!isPaused)         {             //if we are not paused, get the mouse movement and adjust the camera             //position and rotation to reflect this movement around player             Vector2 cameraMovement = new Vector2(Input.GetAxis("Mouse X"),Input.GetAxis("Mouse Y"));              //first we place the camera at the position of the player + height offset             theCamera.transform.position = gameObject.transform.position + new Vector3(0,heightOffset,0);              //next we adjust the rotation based on the captured mouse movement             //we clamp the pitch (X angle) of the camera to avoid flipping             //we also adjust the values to account for mouse sensitivity settings             theCamera.transform.eulerAngles = new Vector3(                 Mathf.Clamp(theCamera.transform.eulerAngles.x + cameraMovement.y * mouseSensitivityY, LOW_LIMIT, HIGH_LIMIT),                 theCamera.transform.eulerAngles.y + cameraMovement.x * mouseSensitivityX, 0);              //then we move out to the desired follow distance             theCamera.transform.position -= theCamera.transform.forward * followDistance;         }     } }


How do I create a resource that I can reference and use in various parts of my program easily?  My specific problem is that I have a NotifyIcon that I want to change the icon of depending on the state of the program. A common problem, but one I've been struggling with for a long time.


Is this the right time to start switching to Salesforce's new Lightning Web Component model (Is this perfectly compatible with Lightning Aura model, Lightning Data Service, Lightning Design System Currently)? Will Aura Component model be completely depreciated and then removed? and in future release I will have to move to LWC model having no Aura components supported?   I am still concerned about this.


A random variable $X$ has the PDF  $$f_X(x)=\begin{cases}   Cx^2 & -1\le x\le 2,\\   0 & \text{otherwise},   \end{cases}$$ and  $Y=X^2$ . Calculate $E(Y)$.


Mboxcox, interpreting difficult regressions

Mboxcox in Stata suggests transforming my variables using a power of 0.1 for the independent variable, and 0.4 for the dependent variable.  I have run the model, and it fixes problems associated with the assumptions of OLS. But certainly, it complicates matters in terms of interpretations.  Please outline possible interpretations and solutions.  Dependent variable is in millions of dollars, and independent variables are number of years.  and a number of dummies which do not require transformation.


I would like to freeze, or in any way disable Google Play on my Android 2.3.6. I tried to prevent the autorun: it always finds its way. I tried to freeze it with Gemini App Manager: even blocked it starts.  How can I definitely block or even uninstall this damned application ? Has someone succeeded in doing so ?  The reason: every time it starts, my whole phone becomes extremely slow, barely usable.


I am running OSX Yosemite. I had free space on my partition, (see picture below) but now it wont delete. I change the format to Mac OS Extended (Journaled), and then when I hit the " + " button it loads for about 1/100 of a second, and then shows on the screen that it partitioned it. When I click away from the partition tab onto the first aid tab, it goes away and becomes free space again. (NOTE: I am trying to MERGE the free space with my first partition, not make a new partition, but i have to make a new one to merge it with my first partition.)


I am using  module but I want to change the taxonomy path from  taxonomy/term/tid to subject/term title.


Is there any way to stop specific sites appearing in browser history?

I am using Firefox and Chrome. There a few websites only which I don't  want anyone to know I visit. But they appear in browser history or when I start typing they also come as auto complete. I have to manually delete them.  Is there any way or add-on which I can install and then I can define the sites that I don't want to appear in history?  Incognito mode is also available, but if I use that, all of my cookies are cleared and I have to enter all my log-in stuff again.


There is relation that is symmetric and transitive but not reflexive?

Let $L=\left\{R\right\}$ be a language with only one relation symbol. Consider these formulas: $\Psi _1\:=\:\forall x\left(R\left(x,x\right)\right)$ $\Psi _2\:=\:\forall x\forall y\left(R\left(x,y\right)\rightarrow R\left(y,x\right)\right)\:$ $\Psi _3\:=\:\forall x\forall y\forall z\left(R\left(x,y\right)\wedge R\left(y,z\right)\rightarrow R\left(x,z\right)\right)\:$ I need to show $Mod\left\{\Psi _1,\Psi _2,\Psi _3\right\}\ne Mod\left\{\Psi \:_2,\Psi \:_3\right\}$.    So far, i understand the meaning of each formula, but i wonder which relation on any domain, can show that  $R$ is symmetric and transitive but not reflexive. Any ideas?    EDITED: Well, i looked at  and it really helpfull! but i want to find other examples just from curiosity ..


If I move an object with my hand, will the object's temperature increase?

From my understanding, temperature is proportional to the average kinetic energy of particles.  If I move an object with my hand, then it will gain kinetic energy. Therefore, its' particles average kinetic energy will increase. Therefore, it's temperature will increase too?


Do I need a visa to enter South Korea while traveling to India from Australia?

I am an Indian national, living and working in Australia for a year. I’m on a bridging visa here. Now I’m going to India and my flight from Sydney is transiting through Seoul airport. It has a layover of more than 20 hours. Can I go out of the airport transit area?


Understanding a recurrence to solve the Coupon Collector problem?

I recently came across this recurrence for the coupon collector problem:  $$\text{draws}(n) = \text{draws}(n-1) \cdot\dfrac{n}{n-1} + 1$$  where $\text{draws}(n)$ is the expected number of coupons to be drawn to get all $n$ unique coupons.  Why is this recurrence true? I would prefer an intuitive approach.


Difference between adding a unit to the interface or the implementation section

If I have a unit that is filled with constants like...  unit AConsts; interface const    Const1 : WideString = 'Const1';    Const2 : WideString = 'Const2';    Const3 : WideString = 'Const3';    Const4 = 100;    Const5 = 100; implementation end.   and I want to use this unit from another unit, is there any difference between...  unit AUnit; interface uses    AConsts; Implementation end.   and   unit AUnit; interface implementation uses   AConsts; end.   ?  The question is not about scope, avoiding circular references etc. It is about differences in the compiled application.  If UnitA, UnitB and UnitC all use AConsts, would there be a difference in the compiled application (assuming no name clashes between the constants in the AConsts unit and other code) between App1 where these UnitA, UnitB and UnitC all have AConsts in the interface section and App2 where UnitA, UnitB and UnitC all have AConsts in the implementation section.


Custom CSS Lightning Web Components - Remove Outline from Input Field

If, for instance, an input field is rendered with lightning-input, and I want to add custom styling e.g. a border color to or remove the outline from the input field. How can I do that? I have tried assigning a class to;  <ligtning-input class="custom-input"></lightning-input>   and then styling the class but seems not to be working.


How can a green laser be reflected as orange?

My friend recently bought a high-powerd pocket laser pen (from China). It is green, and reflects off most surfaces as green.  On some orange surfaces, it reflects orange instead. That is to say, we see an orange dot instead of a green one.  It seems to be certain hard, shiny plastics (for example a Kryptonite bike lock). Orange fruit peel, for example, reflects green, and most orange fabrics reflect green.  I suspect it's some kind of pigment that is reflecting this way.  When the reflection is orange, the intensity of the reflection is subjectively about the same, i.e. it doesn't seem to be losing much energy. If one shined light from a green incandescent bulb onto an orange surface, one would expect that surface to be lit less intensely than a white surface. Not so the laser.  So it seems to be that the photons are being re-emitted at a different wavelength than they were absorbed at.  How can this happen? And why is it only orange?


How does a sport become an Olympic Sport?

How does a sport transition into the Olympics?  What are the qualifications?  Is there a process?


Winter Bash menu does not automatically appear on mouseover

If I open my inbox in the topbar, I can switch to my reputation dropdown or the communities list merely by mousing over the appropriate button. However, I cannot switch to the Winter Bash dropdown by mousing over it; I have to actually click on it (how terrible!). The reverse is also true: if I open the Winter Bash dropdown, I cannot switch to the other dropdowns without clicking on them.  Shouldn't I be able to switch between all four dropdowns just by mousing over them?


Can a Ubuntu computer work on a Windows network?

I have a desktop running Windows XP, and I am seriously considering switching to Linux/Ubuntu once support from MS ends in a few weeks.  However, I have other computers in my house, all running relatively more modern variants of Windows, and thus part of a Windows network.  Can a Ubuntu machine function as part of a Windows network?  I know that I should be able to connect to my router via wire/wireless (although I'm a bit concerned at the number of questions I see regarding various people's connectivity issues in Ubuntu)...I'm just wondering if I'll still be able to do folder/file shares, etc.  Also, if anyone has any suggestions regarding any potential pitfalls I could avoid, that would be great.  Thanks!


I am making an RPG map, and was wondering how to "save" the game.  If you die, you would revert back to a save that happens automatically or manually, and I was wondering how to have it so that you will have all the items you had then, and none of the items you got after you saved (so /gamerule keepInventory won't work).  The only way I can think of doing this is having this long, long, annoying set of command blocks to test for all the items in the game, and then have another 64 command blocks for each of those items, testing for the amount of the item.


When I install a simple program it often uses make && make install and doesn't often even have an uninstall target.  If I wish to upgrade a program, is it standard protocol to assume it just rewrites seamlessly over the old program?  How do I keep track of these programs; do most people just 'fire and forget' and if no uninstall target is given do I have to manually delete everything?


How to tell which image from a set is the most in focus?

I am calibrating the focus on my 35mm film scanner, to do this I am rescanning the same photo repeatedly with different focus configurations and comparing the results to choose the configuration which produced the most in focus scan.  However, it occurred to me that software could probably determine the most in focus of the scans better than I could.  Is there any software which can tell me which scan is the most in focus?


How to upgrade from 12.04 to 12.10 using CD?

can anyone tell me how to upgrade from ubuntu 12.04 to 12.10 from a Cd


I recently bought  from a used equipment auction. I installed Xubuntu [Ubuntu 14.04 LTS (32 bit)] and decided to try if I can play CounterStrike:Source using Steam here. After installation, I got this message:    I tried a few remedies advised on-line, like  sudo add-apt-repository ppa:ubuntu-x-swat/x-updates sudo apt-get update sudo apt-get dist-upgrade   and  sudo apt-get install xorg-x11-drv-catalyst-devel.i686 xorg-x11-drv-catalyst-libs.i686   but got no results.


Proving that addition of partial derivatives of square of an holomorphic function equals to four times its first derivative square.

I am looking for a hint for the following exercise:             Assuming $f(z)$ as an entire function, prove that      $$\left(\frac{∂^2}{∂x^2}+\frac{∂^2}{∂y^2}\right)\cdot|f(z)|^2=4\cdot|f'(z)|^2$$   I suppose that solution involves using Cauchy–Riemann equations, but I´m not sure  about how to do it


find an ordered basis ot prove it doesn't exist


Will   $(document).ready    in parent page wait for iframe content to be loaded completely?  I have a parent page in which there is a an iFrame. After the iFrame is completely loaded I need to invoke a function in the iFrame from the parent page.


I already have a Jolteon and a Flareon and I know that I can get a Vaporeon by renaming it to Rainer, assuming that is a valid way. My question is how do you get Umbreon and Espeon?


while making a call from php i am getting the error      Attempt to de-reference a null object Class.Demo.Insert:   What is problem in my webservice?  global class Ctest{     global class RequestClass{         webservice String accName;     }      webservice static void   cInsert(RequestClass req){         Account a1 = new Account();         a1.Name = req.accName;         insert a1;     } }   And Our Php Code Is  require_once('salesforceAPI/soapclient/SforceEnterpriseClient.php'); require_once('salesforceAPI/soapclient/SforceHeaderOptions.php');  $sfdc = new SforceEnterpriseClient(); $SoapClient = $sfdc->createConnection('enterprise.wsdl.xml');  $loginResult = false;  $loginResult = $sfdc->login(USER, PASSWORD . SECURITY_KEY);  $parsedURL = parse_url($sfdc->getLocation()); define("_SFDC_SERVER_", substr($parsedURL['host'], 0, strpos($parsedURL['host'], '.'))); define("_WS_NAME_", 'salesforceAPI/Ctest'); define("_WS_WSDL_", _WS_NAME_ . '.xml'); define("_WS_ENDPOINT_", 'https://' . _SFDC_SERVER_ . '.salesforce.com/services/wsdl/class/' . _WS_NAME_); define("_WS_NAMESPACE_", 'http://soap.sforce.com/schemas/class/' . _WS_NAME_);  $client = new SoapClient(_WS_WSDL_); $sforce_header = new SoapHeader(_WS_NAMESPACE_, "SessionHeader", array("sessionId" => $sfdc->getSessionId())); $client->__setSoapHeaders(array($sforce_header));  $method = $client->__getFunctions();  $wsParams = array('accName' => 'XXXXXXX');  $client->cInsert($wsParams)


In German there is a pattern for counting items from the end of a list. The last item is "das letzte", the one before is "das vorletzte", the one before that is "das vorvorletzte" and for each other item there's just another "vor" added.  While searching for an English translation for the German word "vorvorvorletzte" I came across   and  but none of them showed any usage pattern. Furthermore I didn't find any indication of which variant ("to", "from", no preposition) is used most nor to what area of the world those translations apply.  So I am still wondering: When there are items 1, 2, 3, 4 and 5, how can/will item 2 be called?   third from last? fourth from last? anteantepenultimate? fourth-last? fourth to last? the last but three item? the last but four item?   Is this a question of dialect/local use?


identical formatting of two underlined lines have different vertical spacing

I'm new to latex but using it to format my CV. I have several sections like the one below, where I expect the two headings "Instruction" and "Lectures and Workshops" to look identical. \section{\sc Teaching} \underline{Instruction}\vspace{1.5mm}\smallskip \\ Teaching assistant, ... \smallskip \smallskip \\ \underline{Lectures and Workshops}\vspace{1.5mm}\smallskip \\ Using data science ... \smallskip \smallskip \\  However, as you can see in this picture, the first underlined line looks much more cramped than the second, which has more spacing between the text and the underline. Does anyone know what might be causing this and how to fix it?


I have seen it mentioned places that re-open votes expire, but the  makes no mention of that. Do re-open votes expire, and if so how long does it take until they expire? In addition, is there any way to view the total number of re-open votes a question has received over it's lifetime, such as with the ? Edit I have found a few meta links referencing re-open votes expiring, and am now trying to determine if these are current or not.      The last link seems to be the most current, however I am hoping that someone who knows the current expiration rule can confirm this. I also would like to know if there is a way to see total re-open vote counts anywhere.


What is the general protocol to name something after somebody (some people)?

In mathematics (and other sciences) there are thousands of concepts, theorems, lemmas, etc which are named after some mathematicians (scientists). However, this nominations are not always very straightforward, especially if we are going to assign a new name for new concepts. For example, I can imagine the following scenarios and I would like to know what general protocol we should apply in each case:    A concept may have several origins in different fields and due to several individuals.  A concept is built on another concept which already have a name and this can happen several times. For example "Hecke pairs" is a concept in mathematics, then Bost and Connes make a particular Hecke pair famous, so we have "the Bost-Connes Hecke pairs". Should we name all influential people  in each stage of advancement of a concept? If an author invents a concept, is it appropriate to name it after him/herself,  or he/she should wait others call it after his/her name? A concept was invented by some author "X" in long time ago, and then it has evolved to something very modern and somehow different. Should we still call it by the name "X"?    Please do not hesitate to add new items if you can imagine other scenarios too.  Finally, I would like to ask another related question:  Can we use acronyms in stead of the full names, especially if the names of several people are involved?


Why man read don't contain any argument description in my debian?

As far as i know that read in bash contains many argument such as -a -d -e -r. The webpage list all arguments of read.  In my console, man read contains no argument on it. I upload man read > read.txt into dropbox,please download it and verify.


Can I transfer/Migrate Windows server 2003 RDS cals to Windows Server 2012 R2?

I have 9 W2K3 RDS (Terminal Services) CALs, if I upgrade to Windows server 2012 R2, Can I transfer/migrate the CALs to the new server?  Thank you,


How does the << operator works in the following line

I have come across a line of code. int m_iCorners = 30 , m_iTesselation2 = 10; int iNeededSize = (4 + (m_iCorners + 1) * (m_iTesselation2 << 1));  what is the role of << operator in the code above and how does it affect the m_iTesselation2 value?


How do i revert back to windows vista from ubuntu 12.10 on a Packard Bell laptop

I bought the laptop on ebay and i dont have any discs for ubuntu or windows vista.  The stickers on the laptop indicate the factory settings as having vista installed.  Pressing Alt and F10 at startup to go into restore doesnt do anything.


Unable to retrieve length of an entity of JSON data in JavaScript

I'm supposed to read certain data from a JSON file :    I'm able to print the correct value for :  console.log('data1 ' + data.entry[0].id); console.log('data2 ' + data.entry[0].content.properties.yyn);   However, I want to find the length of the properties instead of reading each entity inside properties. I tried:  console.log('data2 ' + data.entry[0].content.properties.length);    It did not work!


$H \leq G$ s.t. $|G : H|$ is the least prime dividing $|G|$. Show $H$ is normal in $G$.

Let $G$ be a finite group, $H \leq G$ such that $[G : H]$ is the least prime which divides $|G|$. Show that $H$ is normal in $G$.  Can someone explain what information we get from knowing that $[G : H]$ is the least prime which divides $|G|$? By Lagrange, $|H| = \frac{|G|}{[G : H]}$. Since $[G : H]$ prime, then $|G|$ should be a power of that prime. By Sylow theorem $1$, then there is a Sylow $p$-group (where $p$ is the prime) with order $p^n$. I don't know if this is the correct path and I also don't know why we care about the least prime.  If someone can explain the solution for this exercise, I would be grateful. I've been banging my head on this for forever.


Is there any ways I can download Google Chrome 32 bit deb file for Ubuntu?

Where can I download Google Chrome for Ubuntu Desktop 16.04 LTS 32 bit?


What do I get from a skill being Legendary?

I recently got my Blacksmithing skill to 100. Now in the skills menu I can press space to make it Legendary, which will put it back to a skill level of 15 and reset my perks.  I am wondering: What benefit is there from making a skill Legendary apart from being able to level up the skill more thus having infinite levels?


Virtual Photon in Electron Scattering Feynman diagram

If we know that the virtual photon emitted in an electron scattering Feynman diagram violates the energy and momentum conservation laws (though temporarily), why do we accept it as a feasible diagram representing another perspective of reality?


"One of the sources of water in our country ARE the rivers"

"One of the sources of water in our country are the rivers" in this sentence, wasn't it supposed to be 'is' instead of 'are'? Normally we say "One of my friends is responsible for this," don't we?


SSH login with expect(1). How to exit expect and remain in SSH?

So I wanted to automate my SSH logins. The host I'm with doesn't allow key authentication on this server, so I had to be more inventive.  I don't know much about shell scripting, but some research showed me the command 'expect' and some scripts using it for exactly this purpose. I set up a script and ran it, it worked perfectly to login.  #!/usr/bin/env expect -f  set password "my_password"  match_max 1000  spawn ssh -p 2222 "my_username"@11.22.11.22  expect "*?assword:*" send -- "$password\r" send -- "\r"  expect eof   Initially, it runs as it should.  Last login: Wed May 12 21:07:52 on ttys002 esther:~ user$ expect expect-test.exp spawn ssh -p 2222 my_username@11.22.11.22 my_username@11.22.11.22's password:  Last login: Wed May 12 15:44:43 2010 from 20.10.20.10   -jailshell-3.2$    But that's where the success ends.  Commands do not work, but hitting enter just makes a new line. Arrow keys and other non-alphanumeric keys produce symbols like '^[[C', '^[[A', '^[OQ' etc.[1]  No other prompt appears except the two initially created by the expect script. Any ignored commands will be executed by my local shell once expect times out. An example:  -jailshell-3.2$ whoami ls pwd hostname   (...time passes, expect times out...)  esther:~ user$ whoami user  esther:~ ciaran$ ls Books       Documents   Movies      Public       Code        Downloads   Music       Sites        Desktop     Library     Pictures    expect-test.exp  esther:~ ciaran$ pwd /Users/ciaran  esther:~ ciaran$ hostname esther.local   As I said, I have no shell scripting experience, but I think it's being caused because I'm still "inside of" expect, but not "inside of" SSH. Is there any way to terminate expect once I've logged in, and have it hand over the SSH session to me?  I've tried commands like 'close' and 'exit', after " send -- "\r" ". Yeah, they do what I want and expect dies, but it vindictively takes the SSH session down with it, leaving me back where I started. What I really need is for expect to do its job and terminate, leaving the SSH session back in my hands as if I did it manually.  All help is appreciated, thanks. [1] I know there's a name for this, but I don't know what it is. And this is one of those frightening things which can't be googled, because the punctuation characters are ignored. As a side question, what's the story here?


I have a question, I have installed Ubuntu 14.04 and on this machine is icinga software. when I opened the terminal and typed:   sudo vi /etc/icinga/objects/localhost.cfg   then the terminal opened the file, but I can't type in this file. When I type "d" then the terminal delete everything in the file.


How to tell GRUB my system isn't anymore dual booting Windows?

I started using Ubuntu along with Windows, then i decided to remove Windows entirely and just use Ubuntu. The problem is that everytime i boot my computer i see the grub screen, then i have to select "Ubuntu" to start the system. Altough it's not a big deal, i would like the system to boot Ubuntu immediately.  I'm using ubuntu 19.10.  Edit: i tried editing /etc/grub/defaults with any combination of GRUB_TIMEOUT et al settings i could find online and save it with update-grub but with no luck, it seems it ignores every directive i put there.


Cannot delete apt-fast for a clean install

This is my problem:  $ destroy apt-fast [sudo] password for colbyryptos:  Reading package lists... Done Building dependency tree        Reading state information... Done Package apt-fast is not installed, so not removed 0 upgraded, 0 newly installed, 0 to remove and 14 not upgraded. 1 not fully installed or removed. After this operation, 0 B of additional disk space will be used. debconf: DbDriver "config": /var/cache/debconf/config.dat is locked by another process: Resource temporarily unavailable Setting up man-db (2.6.1-2) ... debconf: DbDriver "config": /var/cache/debconf/config.dat is locked by another process: Resource temporarily unavailable dpkg: error processing man-db (--configure):  subprocess installed post-installation script returned error exit status 1 Errors were encountered while processing:  man-db E: Sub-process /usr/bin/dpkg returned an error code (1)   I have also tried sudo rm /var/lib/dpkg/lock, followed by sudo dpkg --configure -a.  It then gives me this  $ sudo dpkg --configure -a [sudo] password for colbyryptos:  Setting up man-db (2.6.1-2) ... debconf: DbDriver "config": /var/cache/debconf/config.dat is locked by another process: Resource temporarily unavailable dpkg: error processing man-db (--configure):  subprocess installed post-installation script returned error exit status 1 Errors were encountered while processing:  man-db


Elements and structure of $\text{Gal}(\mathbb Q(\zeta_{21}):\mathbb Q)$

Let $\zeta_{21}$ be a primitive 21st root of 1. Describe explicitly the elements of the Galois group $\text{Gal}(\mathbb Q(\zeta_{21}):\mathbb Q)$ and determine the structure of this group.   From finding the minimal polynomial I know that the order of the Galois group must be 12. So $\text{Gal}(\mathbb Q(\zeta_{21}):\mathbb Q)≅(\mathbb Z/21\mathbb Z)^{\times}$.  I have seen online that $(\mathbb Z/21\mathbb Z)^{\times}$ has the structure $C_2 \times C_6$, how has this been found?   How can I describe the elements of this Galois group?


Liquid exuded by frozen chicken breast: what's in it?

I have a wonderful Chicken Quesadilla recipe that involves cooked and shredded boneless/skinless chicken breast. I generally poach the whole breasts in a frying pan with chicken broth or a little water, and it comes out quite tender and easy to shred.  When I start by defrosting frozen chicken, I end up with a thick liquid in the bag of chicken. Thinking that it would be a reasonable broth substitute, I have several times tried poaching in that liquid instead of the broth or water. But, each time a strange thing happened: the liquid seemed to curdle, looking a bit like someone had stirred in some small-curd cottage cheese. It's certainly not dangerous, but it isn't very appetizing.  What is it in the liquid from a defrosted chicken breast that curdles when heated? Is it inherent in the chicken, or something added at the processing plant (I generally use Perdue)?


If $(X_n)_n$ is i.i.d. and $\frac{S_n}{n} \to a$ almost surely then $a=\Bbb E[X_1]$

$(X_n)_{n \in \Bbb N}$ independent and identical. $S_n = \sum_{i=1}^n X_i$ Now I want to show: $$\frac{S_n}{n} \xrightarrow{\text{almost surely}} a, \mathrm{with}\: a \in \Bbb R\Rightarrow a=\Bbb E[X_1]$$ In our lecture we showed: $(X_n)_{n \in \Bbb N}$ independent and identical, with $\Bbb E[X_1] \lt \infty$ , then $\frac{S_n}{n} \xrightarrow{\text{almost surely}} \Bbb E[X_1]$  In other words, either there's a problem with the uniqueness of the limit or the fact that we don't know from the start if the expectation values are finite. I'm stuck on this problem. Does someone have any ideas or tipps on how to solve this? Thanks in advance!


Windows 7 - Additional RAM installed, but usable amount did not increase?

We have just upgraded a PC running Windows 7 Enterprise Edition (32bit) to have 4gb of memory instead of 2gb.  Previously, there was 989mb of usable memory (with 2gb total installed). After upgrading, the computer now shows 4gb of total memory with 989mb usable.  Why has the available memory not increased? How can I make this memory available for usage?  As stated, it is recognizing the memory but not showing it as usable memory.  Thanks.  Update  Looking at Resource Monitor, it appears that the Hardware Reserved Memory is 3gb. So when I inserted the additional 2gb of memory, it was all taken as Hardware Reserved Memory and added not a single MB to Usable Memory.   What could cause this?  My other machines are only reserving roughly 1gb.  Update - Solution Found  It looks like the graphics card was faulty and consuming all RAM except for 989mb regardless of how much RAM was installed. It has been replaced with a different graphics card and Usable Memory is now what was expected (Roughly 3gb).  Thanks for all the answers!


Why do Outdated Page and Cache Removals self-happen in Google Webmaster Tools?

Take a look at the following screenshot I took from Google Webmaster Tools "Remove URLs" page:   None of these were performed by me or others who have access to GWT.  How do these removal requests happen without us doing any requests?  Why is that happening?  How to stop that or is there any point in stopping that?


What particles make up a ? We all know quarks (3, uud) make up a proton.  I read on Wikipedia they are called "hadrons" ,but how do they work?  Is the collection wave functions of the components of the quark representative of the wavefunction of the quark itself?


How can I prove that $X+Y$ is a Poisson process with parameter $\lambda_X+\lambda_Y$?

For 2 independent Poisson processes $X,Y$, with parameters $\lambda_X, \lambda_Y$ respectively, how can I prove that $X+Y$ is a Poisson process with parameter $\lambda_X+\lambda_Y$?  To do this, I suppose you would use the rule $$ P(X+Y = k) = \sum_{n=0}^k P(X = n) \cdot P(Y = k-n) \\ = \sum_{n=0}^k\frac{\lambda_X^n e^{\lambda_X}}{n!} \cdot \frac{\lambda_Y^n e^{\lambda_Y}}{(k-n)!} $$  However, I am unsure of how to continue from here. Can anyone prompt me in the right direction?


Finding the minimum value of $a^2+b^2+c^2$

Let $a$, $b$ and $c$ be $3$ real numbers satisfying $2 \leq ab+bc+ca$. Find the minimum value of $a^2+b^2+c^2$.    I've been trying to solve this, but I don't really know how to approach this. I thought of $(a+b+c)^2 = a^2+b^2+c^2 + 2(ab+bc+ca)$, but that gives me  $a+b+c$, which is unknown. How can I solve this?


Regex expression to accept alphanumeric characters and only one @ symbol

I am wrting a javascript if the accepted value is other than alphanumeric characters and symbols _.-@ , it should throw an alert.   I have used below expression, however concern is that I need only one mandate occurence of @ symbol. How can I do that?  !/^[ A-Za-z0-9_.-@]*$/


When a familiar delivers a Touch spell, who should be Helped?

Picture this situation. Myself and a friend are a pair of casters, both with familiars. My friend's familiar has just gotten in position next to an enemy we're fighting, and I know he intends to use his upcoming action to have the familiar deliver a touch range attack spell (such as Shocking Grasp), per Find Familiar...     Finally, when you cast a spell with a range of touch, your familiar can deliver the spell as if it had cast the spell. Your familiar must be within 100 feet of you, and it must use its reaction to deliver the spell when you cast it. If the spell requires an attack roll, you use your attack modifier for the roll.   My familiar's turn comes up, but I won't need its help when it's my turn for whatever reason. Instead, I want it to use the Help action to help my friend's spell land, so I order it to move next to...  ...who? The caster, or the familiar?


Any possibility to align the fractions (units in general) too?  Wobei: \begin{flalign*} \noindent \tab \rho _{KOH} & = 2.04 \frac{g}{cm^3} &\\ M_{KOH} & = 56.10 \frac{g}{mol} &\\ c_{KOH} & = 0.05 \frac{mol}{L} &\\ \end{flalign*}   If I add another & they end up completely at the right.


It might be useful to encourage existing users of stackoverflow to cross pollinate other stack exchange sites.  While rep-sharing is not useful, as rep is meant to be a measure of expertise in one subject, badges may be one way to encourage participation across many sites.  This was triggered by seeing how few people actually had greater than 1k rep on all three main sites (SO, SF, SU) via Dennis Williamson's  app.  I had tried to do this by hand prior to the API under the assumption that many people would be answering questions on all three sites, but it turns out there are only 33 people, of all the users of stackoverflow, that have a 1k+ reputation on all three sites.  Over time it may be useful to provide badges that appear on all sites one is participating in that are awarded for extraordinary participation in the whole universe of Stack Exchange sites.  For instance, a silver badge might appear on all my profiles if I obtain 1k rep on 5 or more sites, and a gold badge if I have more than 3k rep on 5 or more sites.  I would hesitate extending this much past 5 sites as we don't want to encourage spamming questions and answers on sites where the user has little interest, but across the universe of stackapps I know I'm proficient or expert in at least 10 current sites, and while it's not a big nudge, the idea that I can get extra awards - especially ones that appear on all sites I'm in - would move me to participate a little more on sites that I am registered on, but don't visit regularly.    I expect, eventually as sites are launched, most users of any one site will have some interest or knowledge in at least 5 other sites.  This may provide the extra nudge some sites need to maintain an excellent rating in terms of usage.


Python changing one element on one list of 2d list

I am trying to create a game like Battleship in Python. My current code hides a ship and if you guess the location of the ship (the coordinates are displayed for debugging purposes). My error is that it is changing the text for an item for all the rows rather than just one.  from random import randint board = [] board = [["O"]*5]*5 def print_board(board):     for row in board:         print(" ".join(row)) print_board(board) ship_row = randint(0, len(board)-1) ship_col = randint(0, len(board[0])-1) print(ship_row, ship_col) gr = input("Guess row: ") gc = input("Guess column: ") if gr == ship_row and gc == ship_col:     board[ship_row][ship_col] = "X" print_board(board)


"Window replacement company" or "Windows replacement company"

My client says:      "We are a trusted windows and doors replacement company."   It sounds funny. It seems like it should be singular: window and door.  Although, if it is part of the name "Acme Windows and Doors" it sounds correct.


git: How to change the commit message of an already committed file, non interactively?

I have a situation where a committed file is reviewed by the bug tracker tool and once it reviews the commit message has to change.  So my question is, Is there a way to change the commit message of a file that is already committed into my local git repository?


Is it ok to install the recent version of Ubuntu in the core i3 processor. Is there any issue coming after installing that. I am new to Ubuntu.


Entire Function is Constant with $Re(f(z))^2 = Im(f(z)) \forall z \in C$

Suppose $f$ is an entire function with $Re(f(z))^2 = Im(f(z)) \forall z \in C$. Show that $f$ is constant. So far, I have that since $f$ is entire, we can use cauchy riemann equations and hence $u_x = v_y , u_y = -v_x$. Let $f = u+iv$ where $U,V$ real valued functions so Now we have that $Re(f(z))^2 = u^2 =v = Im(f(z)$. We get : $v_x = 2u\cdot u_x= -u_y$ and $v_y = 2u\cdot u_y = u_x$ by the C-R equations. Now I am unsure as to where to go next. My idea is equating $2u = u_x/u_y = -u_y/u_x$ and proving that this implies $u$ is a constant. Is this correct? Is there a better approach to this? How can I go about proving the final equality easily?


Use Windows Live ID, but login with a different password

Is it possible to keep my account linked to my Windows Live ID, but use a different password for logging on to my computer?  I know I can set up a PIN or a picture password for logging in locally, and those obviously aren't required for signing into my Live account on other devices (my Xbox, for example).   I don't want to set up a PIN or picture password, but I would like a password separate from my Live ID.