I bricked my phone via the official Kies update function and now I want to restore it with Odin. However, I find no place where you can download the current firmware files, most of the sites are only for registered users or the file is taken down... Does anyone know an official firmware repository or something similar? My model number is GT-N7100.

There are several reasons to be looking for a ROM:   Upgrading or downgrading your stock ROM Looking for firmware from a different region/language Flashing a custom ROM for different features, removing bloat, etc.   But where can one find ROMs in the first place?  What sites are likely to have the ROM I need?  ; please add to the wiki answer instead of posting separate answers.  See also:


Let p be a prime with p > 7. Prove that there are at least two consecutive quadratic residues modulo p. [Hint: Think about what integers will always be quadratic residues modulo p when p ≥ 7.]

For any prime $p\gt 5$,prove that there are consecutive quadratic residues of $p$ and consecutive non-residues as well(excluding $0$).I know that there are equal number of quadratic residues and non-residues(if we exclude $0$), so if there are two consecutive quadratic residues, then certainly there are two consecutive non-residues,therefore, effectively i am seeking proof only for existence of consecutive quadratic residues. Thanks in advance.


In a large base document  \documentclass[10pt,onecolumn]{article}   I use   \pagestyle{myheadings} \markboth{ }{my main document heading text}   to set the headings.  I am also using the pdfpages package to include a multi-page document within my base document as follows:  \includepdf[pages={1-},scale=.95]{myMultiPageDocument.pdf}   I would like to set the heading within the base document showing the added document and tried  \markboth{ }{my new heading text here}  \includepdf[pages={1-},scale=.95]{myMultiPageDocument.pdf}   but no headings were rendered.  (I cannot set headings within myMultiPageDocument.pdf.)  How do I create new headings for the pages showing the included document?

I have a chapter of attachments which contains pdf files in this format, using the awesome pdfpages package:  \chapter{Title} Lots of multipage pdfs following \includepdf[pages=-,frame,scale=0.9]{abc.pdf} \includepdf[pages=-,frame,scale=0.9]{def.pdf} ...   This works, but apparently clears out the header and page numbers of the parent document. What setting do I have to change to get back the header and page numbers?


Is it possible to create a default "table" (not programatically) in sqlite and have eclipse compile it into the apk? Basically I want a table file that the program can then later access to get information from.  Edit: Just to add more information: What I want to do is create a file that can be added in the "res" folder that has a table (containing all the values I wish to add to the DB). These will be treated as "constants" and I will use the "KEY" value to link them to the other tables that will be done within my program.  However I apologize, I did not originally find the answer to my question. Thanks for the help!

If your application requires a database and it comes with built in data, what is the best way to ship that application? Should I:   Precreate the SQLite database and include it in the .apk? Include the SQL commands with the application and have it create the database and insert the data on first use?   The drawbacks I see are:   Possible SQLite version mismatches might cause problems and I currently don't know where the database should go and how to access it. It may take a really long time to create and populate the database on the device.   Any suggestions? Pointers to the documentation regarding any issues would be greatly appreciated.


I am developing a school management system, where the database has been simplified as given below:-  users(id, email, password);  students(id, user_id, roll_no, first_name, last_name, dob); teachers(id, user_id, name, qualification); guardians(id, user_id, name, phone, address);   From the database it is cleared that, we have a common login system for all kinds of profiles.  Problem: I can access a user credentials from a given profile such as students or teachers as there is a foreign key associated into the profile table. But to know the type of profiles associated to a user, I can not go down without searching each profile table.  What I have tried: I have created an intermediary table such as:-   user_profiles(id, user_id, table_name)    But this does not seems to be efficient as I need to code extra. Is their any way to associate users table to their respective profile table in the database layer itself?

Well here's my problem I have three tables; regions, countries, states.  Countries can be inside of regions, states can be inside of regions.  Regions are the top of the food chain.  Now I'm adding a popular_areas table with two columns; region_id and popular_place_id.  Is it possible to make popular_place_id be a foreign key to either countries OR states.  I'm probably going to have to add a popular_place_type column to determine whether the id is describing a country or state either way.


As I walked through the channel — I knew it was over.  Is this a correct usage of the em dash?

I generally know how to use a hyphen, but when should I use an en-dash (–) instead of an em-dash, or when should I use a hyphen (-) instead of an em-dash (—)?


I am confused about the age of the Universe.   If you calculate it by $1 / H_0$, won't the answer be roughly the same today as it will be 30 billion years from now?  I know $H_0$ is a parameter, not a constant, but it doesn't change that much, does it?  And if the expansion is accelerating then $H_0$ is going up, implying the age of the universe $1 / H_0 $ was higher in the past than it is today.

Why we call "constant" to the Hubble constant?,  if the universe were really expanding then the Hubble "constant" should change, being variable, smaller and smaller..with "time".  Other example/view of this question: if Hubble constant were constant then the universe "age" would be constant too,  so let's say 13.7 billion years, and stop growing. That's not an expanding universe.  On the other hand:  If the Hubble constant and universe age were not so constant then:  There is some property that is changing like a "time" that -everyone in universe- could get same number, so there would be an absolute time..   I see the Hubble Constant, and even the age of the universe, a really too speculative theory (perhaps it is as speculative as the posibility of measuring), having more accuracy will lead to better theories...  Is it because some theoric impossibility in measuring that kind of variation?   I see a lot of inconsistency. Any light at this respect is welcome, thanks


Let $p$ be an odd prime, and let $a$ be an odd integer such that $p \nmid a .$ Prove that $$ a^{p-1} \equiv 1 \quad(\bmod 2 p) $$  I thought about Fermat Little Theorem could be useful but for that we need prime in modulo. But her we have 2p so it is an even integer. Can somebody give me hint for how to proceed?

$p,q$  primes, $(pq,a)=1$ and $p-1|q-1$ then prove $a^{q-1}\equiv 1\pmod{pq}$   Got this in an exam today and had no idea how to do it.


I used the following command after finding it on a thread:  $ sudo dpkg -i --force-overwrite atom-amd64.deb  (Reading database ... 256705 files and directories currently installed.) Preparing to unpack atom-amd64.deb ... Unpacking atom (1.19.1) over (1.19.1) ... dpkg: dependency problems prevent configuration of atom:  atom depends on git; however:   Package git is not installed. dpkg: error processing package atom (--install):  dependency problems - leaving unconfigured Processing triggers for bamfdaemon (0.5.3+17.04.20170406-0ubuntu1) ... Rebuilding /usr/share/applications/bamf-2.index... Processing triggers for gnome-menus (3.13.3-6ubuntu5) ... Processing triggers for desktop-file-utils (0.23-1ubuntu2) ... Processing triggers for mime-support (3.60ubuntu1) ... Errors were encountered while processing:  atom   I am able to open and use atom. No problems yet. But should I  do anything about the  error message?

Say, I have foo-1.2.3.deb which depends on perl and python, however, running command:  dpkg -i ./foo-1.2.3.deb   won't install these dependencies. So I must apt-get install perl python by hand.  How to make dpkg -i install these dependencies for me automatically?


When I run df -h, I have the following output, indicate that /dev/sda6 which mounted on / is using 100% disk space.  Filesystem            Size  Used Avail Use% Mounted on /dev/sda6              29G   29G   34M 100% /   I navigate to /, I run  du -h -a --max-depth=1 | sort -h   to see which folder use the most spaces. I got only a result of 2.6 GB diskusage.  2,6G    . 1,2G    ./usr 573M    ./opt 448M    ./var 114M    ./lib 93M     ./root 87M     ./home 7,5M    ./etc 5,8M    ./sbin 5,7M    ./bin 4,3M    ./lost+found 3,6M    ./lib32 8,0K    ./dev 0       ./vmlinuz 0       ./tmp 0       ./sys 0       ./srv 0       ./selinux 0       ./proc 0       ./mnt 0       ./media 0       ./lib64 0       ./initrd.img 0       ./forcefsck 0       ./ext 0       ./dead.letter 0       ./boot 0       ./000-default-ssl   Running du -h -s -x / as suggested in the comments also shows only 2.6 GB used, where df -h says I have 29GB used for /dev/sda6 which is mounted at /.  Where are the rest of the files?

When I sum up the sizes of my files, I get one figure. If I run du, I get another figure. If I run du on all the files on my partition, it doesn't match what df claims is used. Why are there so many different figures for the total size of my files? Can't computers add?  Speaking of adding: when I add the “Used” and “Available” columns of df, I don't get the total figure. And that total figure is smaller than the size of my partition. And if I add up my partition sizes I don't get my disk size! What gives?


So the question is pretty strange. I wrote an algorithm to move contents of any list (array) by a given number of digits to the left.  DIGS = [ 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 ]  # move functions def move(arr):     this = arr     first = this[0]     for b in range(len(this) - 1):         this[b] = this[b + 1]     this[-1] = first     return this  def move_with_step(arr, step):     this_arr = arr     for a in range(step):         this_arr = move(arr)     return this_arr   And, obviously, when typing print(move_with_step(DIGS, 5) will give us the same DIGS array but twisted. It will be something like [ 5, 6, 7... 3, 4 ]. You get the idea. And in this case it works. BUT...     The problem is: if I'd put this same call into the for loop like below or just one after another, it will give me wrong results which is kinda strange because it should'n modify DIGS itself and why is that happening IDK.   So this code  for a in range(1, 6):     print(move_with_step(DIGS, a))   Returns this  [1, 2, 3, 4, 5, 6, 7, 8, 9, 0] [3, 4, 5, 6, 7, 8, 9, 0, 1, 2] [6, 7, 8, 9, 0, 1, 2, 3, 4, 5] [0, 1, 2, 3, 4, 5, 6, 7, 8, 9] [5, 6, 7, 8, 9, 0, 1, 2, 3, 4]   in the console. Which is crazy and totally wrong. Why is that?

I'm trying to understand Python's approach to variable scope. In this example, why is f() able to alter the value of x, as perceived within main(), but not the value of n?  def f(n, x):     n = 2     x.append(4)     print('In f():', n, x)  def main():     n = 1     x = [0,1,2,3]     print('Before:', n, x)     f(n, x)     print('After: ', n, x)  main()   Output:  Before: 1 [0, 1, 2, 3] In f(): 2 [0, 1, 2, 3, 4] After:  1 [0, 1, 2, 3, 4]


I have a JSON (All under req.body) in the format   {body :    { Cust : {...} },    { Input : {...} },    { Reciept : {image: [Array] } }  }   I want to be able to remove all the key Reciept so the new JSON would look like ...  {body :    { Cust : {...} },    { Input : {...} } }   I've tried to use delete req.body.Reciept and delete req.body.Reciept.image Both are unable to change the JSON for me. What should I be doing?  edit: When I console log req.body this is what I get :  { body:    { CustData:       { customer: 'T',         address1: '',         address2: '',         billing: '',         signature: [Object] },      InputData:       { InputDate: '2019-10-21 23:25:28',         Workers: [],         Equipment: [],         Purchases: [] },      Reciept: { image: [Array] } } }   I haven't found a solution because I have a JSON and then an array as a value for a key. I am simply trying to remove the whole Reciept key and everything attached to it.  Here is what is I am running  console.log(req.body); delete req.body.Receipt; console.log(req.body);   Here is what I get returned in the terminal   { body:    { CustData:       { customer: 'Test',         address1: '',         address2: '',         billing: '',         signature: [Object] },      InputData:       { InputDate: '2019-10-22 0:9:33',         Workers: [],         Equipment: [],         Purchases: [] },      Receipt: { image: [Array] } } }  //followed by { body:    { CustData:       { customer: 'Test',         address1: '',         address2: '',         billing: '',         signature: [Object] },      InputData:       { InputDate: '2019-10-22 0:9:33',         Workers: [],         Equipment: [],         Purchases: [] },      Receipt: { image: [Array] } } }

Say I create an object as follows: let myObject = {   "ircEvent": "PRIVMSG",   "method": "newURI",   "regex": "^http://.*" };  How should I remove the property regex to end up with new myObject as follows? let myObject = {   "ircEvent": "PRIVMSG",   "method": "newURI" };


I am a math researcher working in number theory. During my college years I heard all the stories of great mathematicians, icons of the subject who dedicated most of their time to mathematics research (think Gauss, Euler etc). And that motivated me. I always seemed to do well in math at college. I secured top ranks at  graduate and undergraduate exams. I cleared the national entrance exam in mathematics (CSIR, India) and got admitted into a Ph.D. programme. Now that I'm pursuing a Ph.D things are not as I had envisioned. There are days where I just don't feel like it. Some parts of math are hard and it seems like a drag. Also I conduct classes thrice a week which I am not enthusiastic about and on some days I just don't wanna do it.   I have this idea of a perfect job where you come in to work everyday and are captivated by what you do and everything just flows. But that's not what I am experiencing. Is this normal? I’m confused. Its not like I have lost interest  rather that I'm not as in to it as I would like to be.

I am a third year (starting fourth year in the fall) PhD student in mathematics. I've passed all qualifying exams and am currently doing research. As far as I can tell, I am not doing poorly. I have the good fortune of having a great advisor, being in a very supportive department, and having friends and family who genuinely care about my success.   The fact is research is hard. It appears to consist primarily of staring at a problem for days and days and days without getting anywhere. Sometimes, rarely, I do figure something out and that feels wonderful, but the overwhelming majority of my time appears to be spent banging my head against a mostly figurative wall. I am not complaining about the material being hard, and I am not averse to putting in hard work, but I get frequently discouraged when I realize the vast volumes of mathematics that I yet know nothing about (and probably never will). It's very hard to quantify progress - in particular, there are too few tangible returns after too many hours worked. I find myself thinking along the lines of "Oh, if only someone actually smart were thinking about this problem they would have solved it in moments" and so on.   I've talked about this to some number of people; here is some advice I have received:   Take a day off. Putting in hours upon hours of trying things doesn't magically lead to a solution, particularly if the brain is tired and just wants to sleep. Have a hobby. Since math research doesn't exactly provide instant gratification, a hobby might provide some instead.  Talk to other graduate students. Realize that many graduate students go through this.   I'm interested to know how other folks have dealt with being discouraged as a graduate student. Does it get better with time and experience? Is this a sign that research is not for me and that I should seriously consider a life outside academia?


I accidentally removed the default user system, ubuntu, from the sudo group. How can I do to regain root access?  Thanks.

In /etc/sudoers I see this:  # Allow members of group sudo to execute any command after they have # provided their password # (Note that later entries override this, so you might need to move # it further down) %sudo ALL=(ALL) ALL   So how do I add a user to that sudo group?


Show that there exist $n!$ total orders on a set with $n$ elements.  Could someone help me with this problem?  I get why this is when seeing an example, just not sure how to write a formal proof.    Example:  For set $\{a,b,c\}$ with $3$ elements we get  $3! = 6$ total orders:  $\{a<b<c, a<c<b, b<a<c, b<c<a, c<a<b, c<b<a\}$

This is from a class question, not looking for someone to do homework for me, just seeking clarification.  Let the set X=(a,b,c)  How many distinct total orders can be defined on this set? Why?  I did search around a bit and from , someone said that for a set of N elements the number of total orders is N!  My question is: is this correct, and why? My class notes define a "total order" as a partial order which is comparable, with a partial order being a relation that is Reflexive, Transititve and Antisymmetric. I get all that, but I'm confused as to how this relates to the question given.


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

This is a homework question whereby I am supposed to evaluate:  $$\sum_{n=1}^\infty \frac{1}{n^2 +1}$$  Wolfram Alpha outputs the answer as   $$\frac{1}{2}(\pi \coth(\pi) - 1)$$  But I have no idea how to get there. Tried partial fractions (by splitting into imaginary components), tried comparing with the Basel problem (turns out there's little similarities), nothing worked.


After trying to explain to my friend that he was misusing "I will like to" in place of "I would like to" and showing him  (I apologize for asking again), he still argues he is correct. He argues he is correct regardless of my "American" english despite me explaining that "will" implies, you can, and WILL DEFINITELY do something. I lack the knowledge to properly counter his argument:  I would have loved to do that(past) I will love to do ( future )

Thank you for your time reading this.  I am from China and have learned British English for years from my middle school to undergraduate time. I normally take 'would' as the past form of 'will', though I know 'would' may also work as an auxiliary verb which could be used in subjunctive mood.  Now I come to the United States and have got confused about 'would' and 'will' very much. In the past, whenever it came to something related to the future, I would use 'will'. Now in the USA, people use 'would' a lot. For example, if we are talking about MIT, some guy may say 'I would go to MIT someday'. For me, I prefer to say 'I will go to MIT someday and I will surely make it!' There are many similar examples.  I know grammatically both sentences must be correct but I just can't understand the usage of 'would' here.  I have looked up some information online. They helped a lot. For example, people say'would' can be used to express your desire or hope. However, from my memory of middle school, it is 'will' that could be used to express your willingness to do something.   According to Merriam-Webster dictionary, both words can be used to express a desire or wish. Then why people prefer 'would' to 'will'?  I am totally lost! People keep using 'would' under those circumstances which I will use 'will' and this really annoys me a lot.  Help!


Ubuntu 16.04 uses three major kernel lines: 4.4.0 (as a base until the end of life) and 4.8.0 and 4.10.0, and with the release of 18.04, 4.15.0. coming. With automatic software upgrade, only line 4.4.0 is updated a long time ago, but it does not handle (yet) Specter & Meltdown syndrome ... Which kernel should I use and where to get it? ....

Any questions relating to status updates, or asking if anything is going to be patched for these vulnerabilities should be closed as duplicates of this question.    are in the news right now and sound pretty severe. I don't see any security updates from Ubuntu that cover these vulnerabilities.  What is Ubuntu doing about these vulnerabilities, and what should Ubuntu users be doing?  These are CVE-2017-5753, CVE-2017-5715 and CVE-2017-5754.


How can I view all the available wifi networks around me?

In Ubuntu 11.04 I used InSSIDer to scan the available APs and sort them by signal strength.  Unfortunately the program seems to be broken in Ubuntu 11.10, and   iwlist wlan0 scan   doesn't return anything meaningful.   What options do I have to scan for available Wireless Access Point, possibly with a GUI?


In glm() function, it seems that you can specify Normal, Gamma, Inverse Gaussian, Poisson, Binomial, and quasi families. See here: . But how do you specify an Exponential distribution?

Let's say I have an outcome that is exponentially distributed, so $p(y|\lambda_i) = \lambda_i e^{-\lambda_i y}$. However, we also know that $\log{\lambda_i} = \beta_0+\beta_1x_i$. If we want to estimate the MLE's for $\beta_0$ and $\beta_1$, what's the best way to do it given data?  I was thinking of using the following code:  summary(glm(y~x,family=Gamma(link="log")))   Not 100% sure what the various arguments are going though.


According to various dictionaries, relevant  means having a bearing    on the matter at hand.      Pertinent  means “relevant to the matter at hand.   Similarly,    What, if any, is the difference?

The dictionary defines relevant as being     Closely connected or appropriate to the matter at hand   whilst pertinent is defined as      Relevant or applicable to a particular matter.   Both of these definitions seem to me to be the same, and the dictionary also defines pertinence and relevance as synonyms. However I feel that in my normal usage I apply a further meaning (something I can't quite articulate) to pertinence.  For example, I see a difference between a relevant question and a pertinent one. Perhaps it's that I see a pertinent question as one which maybe alights on some previously unexplored aspect of the matter at hand, whereas a relevant question explores more familiar ground. Almost as if pertinence requires more insight than relevance.  Does anyone else feel that there is a difference between the two?    Update  So, we're agreed that there is a difference, but I'm still not definitely clear on what that difference is. I think there's maybe more to it than Guffa's suggestion that frequency of use causes pertinence to feel more important. I feel that Robusto might be on to something with impertinence being definitely not the same as irrelevance. I will look into this more when I get the time, but in the mean time I appreciate your help.    Update 2  I've accepted Ghoppe's answer, because I think that one sums up what I'm feeling the best. However (as pointed out by Noldorin in the question comments) I appreciate there's not any real difference at all in their meaning.


I'd like to use dd to create some disk image backups to S3 buckets, however the extra space that's included from empty space is not tolerable. I have thought I could pass it through xz to compress out the zeros, however when this happens, it seems that it's not really losing the empty space padding.  Any ideas on how to properly to pass a dd stream on through a compression algorithm so as to create minimum sized images directly on S3 mounts?  These images will range from tens of MB to tens of GB of data with very little local working space for the upper bounds and so it's necessary to remove the 0s as early as possible (ie, perhaps reducing the buffer or chunk size for the compression tool).

Can I use dd, rsync, clonezilla or any tool to clone only space in use in my hard disk in Linux? I need to do a backup from a 1 TB HD (with only 2 GB space in use) into a 500 GB HD.


This is probably a tough one. It's a short story I read in an SF anthology (of American stories translated in French). It must have been written in the 60s or 70s.  It's about a sort of "time loop", where people are "stuck" in a one night moment, a wild party that repeats itself forever come each new day - which is in fact not a new day, but the repetition of that one same night. Everybody can get wild and crazy and careless, because there are no consequences, everything is back to where it was the next day.  As far as I remember, there isn't much of a big twist, just the main character realizing finally what's going on and that he's also stuck in that forever repeating moment. And that he can have a blast too. But the writing was very vivid, that's why I'm trying to track it down.  Sounds familiar to anybody ? Thanks :)  EDIT : apparently a similar (and much more accurate...) question was already asked, and answered, about this story :  But I feel my entry would still be useful for somebody searching through the "time loop" and "forever party" angles (which is what I remembered), and not "duplicators".

A bank manager gets up, uses his house replicator to make breakfast, then drives to work. he notices that things are wrong, such as damage to the statues on the facade of the bank building. Turns out, the bank is, like society, no longer working - a group of youths are in the bank, and only the janitor is willing to protect him, as long as he opens the vault. Turns out, civilization has collapsed because of replicators - no one works or trades anything except replicated replicators. The banker has a heart attack and dies before he opens the vault, so the janitor feeds his corpse into a replicator and gets a brand new manager, whom he drives home to start the day again. Two lovers among the youths hold each other and drop into a replicator so they can start their life over again, at exactly the same point as the morning since the new bodies are based on a template recorded that morning.  Author and name of story? I keep thinking Disch.


WWN = world wide name Seagate Constellation ES, model ST3500514NS, a 500 GB 3.5" SATA drive It has "serial number", 9WJxxxxx which is eight characters. It has WWN 5000C5002E47xxxx which is a 16 characters. Both are printed on the label on the hard disk drive. WD model WD4001FFSX, a 4 TB SATA drive It has "serial number" WMC5D0Dxxxxx which is 12 characters. It has WWN 50014EE003Fxxxxx which is 16 characters. HGST, model HUC109060CSS600, a 300 GB 2.5" SAS drive It has "serial number" KWJTxxx, also eight characters. It has WWN... I don't know; it is not printed on the label and not plugged into the system to find out.  For inventory, we generally write down and track the following, which can always be gathered from the label on the drive:  Manufacturer Model number Serial number Size in GB or TB, and connection type which is either SATA or SAS Location where in use, or in storage when not in use  The problem arises obviously 1, 2, 3 years later when an inventory sheet shows whatever hard drive. You are pretty sure it's in a running server, but you don't want to shut down the server to pull the hard drive to read the label. How do you get the serial number of the drive that corresponds to what is on the label? udevadm info --query=all --name=/dev/sda has ID_SERIAL, but that is the WWN. We don't want another field to track the 16 characters of the WWN as an identifier... And I already hate writing down the long serial numbers of WD drives. Is there a way in Linux to extract the serial number of the drive? I believe it is possible because years ago the RAID storage manager GUI we had been using nicely reported the eight-character serial numbers of Seagate drives that were in use. And that RAID hardware has listed a bunch of Seagate-specific hard disk drives that were "officially supported", and if memory serves, really no other make/model of drives. Is it possible this is hard disk drive firmware related, meaning it can be done on certain make drives and not others?

I have multiple harddisks which get connected to my server and I'm not sure which one is what in the view of sdXY . If I can see the serial numbers of my harddisks from terminal, I can easily identify them.  Is there any way I can see them from terminal?


I have VF page with renderAs = PDF.  I want to display a chart on that PDF?  I have tried  and   but these only works on HTML, not in renderAs = PDF.  Thanks in advance.

I'm working on a custom report (Visual Force) to generate specific charts(using apex:radar chart) to our client. The problem is that we have to export the information to PDF format. Using the technique of include "renderAs" property on APEX tag, the PDF is generated but the chart isn't included on the PDF and the apex tags, used to show detailed information in a table, seem to be unconfigured. Have anyone ever faced this kind of problem?     Thank you!


When I lift an object from the ground (at a constant velocity) I'm applying force on the object equal to its weight and the earth is also pulling it downwards with equal amounts of force. So if the net force on the object is zero shouldn't the WORK also be zero?...(Although the potential energy increases which indicate work done.....I'm a bit confused.)

The work done against gravity is $mgh$, well at least that's what my textbook says. I have a question: I can apply a force say 50N, so total work done = $mgh + mah$. Where $ma$ = Force. But the truth is irrespective of the force applied, the work done against gravity is always $mgh$. Why?  For example, when I move an object with a force, the work done is more, so work depends on the Force. But in case of gravity it always depends upon the weight


I have two harddisks, mounted on / and /var  I need to migrate the /var partition back into the / partition.  What are the steps required to do this?

I currently only have remote access to this CentOS box, I need to move /var form the primary RAID to a new set of disks that was installed with more space, My current thoughts on how to accomplish this is to temporarily mount the new RAID to /tmp/var. rsync everything from /var to /temp/var then modify the fstab to point /var at the new disks.  Here is my question. how do I delete the existing /var on the primary disks once I have the new disks mounted to that location (assuming this is even possible remotely)?


This returns only the last occurrence in data  re.findall('data-hovercard-id="[\w\W]*"><span>([\w\W]*)</span></a',data)   Whereas this returns all occurrences in the data  re.findall('class="business-attribute[\s]price-range">([\W]*)</',data)   I can't share the data for privacy reasons, but this is scraping and old static html of yelp. Not sure if the structure is still the same.  Any ideas? I'm trying to get all occurrences for both

I have this gigantic ugly string: J0000000: Transaction A0001401 started on 8/22/2008 9:49:29 AM J0000010: Project name: E:\foo.pf J0000011: Job name: MBiek Direct Mail Test J0000020: Document 1 - Completed successfully  I'm trying to extract pieces from it using regex. In this case, I want to grab everything after Project Name up to the part where it says J0000011: (the 11 is going to be a different number every time). Here's the regex I've been playing with: Project name:\s+(.*)\s+J[0-9]{7}:  The problem is that it doesn't stop until it hits the J0000020: at the end. How do I make the regex stop at the first occurrence of J[0-9]{7}?


given an arbitrary triangle, its area can be computed easily by finding the determinant of this matrix: $$ \frac{1}{2}\left( \begin{matrix} x_1 & f(x_1) & 1 \\ x_2 & f(x_2) & 1 \\ x_3 & f(x_3) & 1 \end{matrix} \right) $$ I understand its derivation; what I don't understand (and I have been looking for the answer for the past couple of hours) is that why is the determinant negative if we list the points in the clockwise direction. Please, does anyone know?

According to the  :  If the points are labeled sequentially in the counterclockwise direction, then the area is positive, if they are labeled in the clockwise direction, the area will be negative.  Can anyone please explain why the area is negative, with the change in the order of the points? How does this work? I want to know the logic behind this.


I updated from 20.04 to 20.10, and during the installing updates phase, the system crashed. Is there a way to just update the Ubuntu files, without editing /home? I have a backup from a bit ago but its slightly outdated so wouldn't want to use it. The system thinks it's 20.10

I can't update my system because it freezes while installing a third-party update (zramswap-enabler)! Sometimes I get the following message in Update manager:  Could not initialize the package information An unresolvable problem occurred while initializing the package information. Please report this bug against the 'update-manager' package and include the following error message: E:The package zramswap-enabler needs to be reinstalled, but I can't find an archive for it.  I tried to remove the zramswap-enabler, but it's impossible because I get the following message: dpkg: error processing zramswap-enabler (--remove):  Package is in a very bad inconsistent state - you should  reinstall it before attempting a removal. Errors were encountered while processing:  zramswap-enabler E: Sub-process /usr/bin/dpkg returned an error code (1)  Actually I would really reinstall that package, but it is unable to do it! If I remove this third-party PPA then the system is warning me about a very very serious problem. So why can I not install/reinstall/remove/update this package and why freezes the updater if I try to update?


How I can parse the list of all Mac applications? I am executing:  ls /Library/Preferences/ > apps.txt   But still there are some apps that are missing from the list. I think it parse only user apps and do not parse common apps

Using OSX 10.8.4., I am having a hard time finding a complete list of all software applications installed on my Mac.  Of course, the Launchpad only shows the list of those that have an app shortcut created, excluding those that do not.  I also tried holding down the Option key while in the Apple Menu to change About This Mac to System Information, then Software-->Installations but that still was not a complete list.  How do I get a complete list of all applications installed?


I apologize if this question has been asked before; I couldn't find it in a site search.  I have this sentence about teaching children safety rules:  The rules are different when you are together with your adults or when you are on your own.  My question is about the use of or. Is the sentence correct as it is, or does a different preposition need to be used? and? from? than?   My inclination is to use than because the rules are being compared.

As someone who learned English later on in life, I was taught that different from is the correct grammar to use: this is different from that. However, it seems these days everyone uses different than instead. I know it's incorrect usage, but does the language evolve if the majority wins?  Edit: Some commented different than is American English and different from is British English, both are OK. IMO, this isn't like color versus colour, though.   Than is used after a comparative adjective, e.g. taller than, whiter than. The word different isn't a comparative adjective, unless used in more different than. Logically, it makes no sense to say different than.


How to get log from an android application I want to see the log files of an android app and all of its outputs when it runs. Please tell me how i can do this. Thanks in advance

How can I get crash data (stack traces at least) from my Android application? At least when working on my own device being retrieved by cable, but ideally from any instance of my application running on the wild so that I can improve it and make it more solid.


I have to automate the email signup and verification process using selenium. Any suggestion?Thanks in advance.

Is there any disposable email service that allows receiving verification emails at a temporary address that self-destructs after 24 hours so that it will be helpful in automation of 'customer registration and verification' test case?


I whispered, “I am too young,”   And then, “I am old enough”;   Wherefore I threw a penny   To find out if I might love.   “Go and love, go and love, young man,   If the lady be young and fair.”      —William Butler Yeats, “Brown Penny”   What's the meaning of "If the lady be young and fair.”   "be" is like "is"?

If she be found guilty… ()   I got a curiosity what difference there is when I put ‘is’ instead of ‘be.’ The dictionary says ‘is’ is used in spoken language. Is that all? Is there no semantic difference at all?


Apparently, Landsat 8 occasionally acquires images at night-time during ascending passes. However, in the Google Earth Engine data catalogue (), there is no parameter like "orbit" or "pass".   Is there any other way to filter the Landsat 8 image collection for those night images?

How do I filter Landsat imageCollection by their time of collection?  For example, if they are daytime or nighttime, which might be specified as Ascending or Descending.   I don't know which metadata keyword to use for filtering out by that.


I recently came across the following fact from   list of counterexamples:     There are no polynomials of degree $< 5$ that have a root modulo every prime but no root in $\mathbb{Q}$.    Furthermore, one such example is given: $(x^2+31)(x^3+x+1)$ but I have not been able to prove that this does has that property above. How can such polynomials be generated and can we identify a family of them?

We know that $f(x)=x^4+1$ is a .  My question is:     Is it true that if $f(x)$ has a linear factor over $\mathbb{F}_p$ for every prime $p$, then $f(x)$ has a linear factor over $\mathbb{Q}$?   Edit: Thanks for @Jyrki Lahtonen's answer, I want to do some modifications:     Is it true that if $f(x)$ has a linear factor over $\mathbb{F}_p$ for every prime $p$, then $f(x)$ is reducible over $\mathbb{Q}$?   Thanks in advance!


Why does this have a syntax error   DELETE FROM `print_mailing_request` pmr INNER JOIN `person` p   ON p.id = pmr.person AND p.email LIKE '%@TEST.COM' WHERE  pmr.sent_to_fulfiller != 'y'   when this works correctly without error?  SELECT * FROM `print_mailing_request` pmr INNER JOIN `person` p   ON p.id = pmr.person AND p.email LIKE '%@TEST.COM' WHERE  pmr.sent_to_fulfiller != 'y'

Here is the script to create my tables:   CREATE TABLE clients (    client_i INT(11),    PRIMARY KEY (client_id) ); CREATE TABLE projects (    project_id INT(11) UNSIGNED,    client_id INT(11) UNSIGNED,    PRIMARY KEY (project_id) ); CREATE TABLE posts (    post_id INT(11) UNSIGNED,    project_id INT(11) UNSIGNED,    PRIMARY KEY (post_id) );   In my PHP code, when deleting a client, I want to delete all projects posts:  DELETE  FROM posts INNER JOIN projects ON projects.project_id = posts.project_id WHERE projects.client_id = :client_id;   The posts table does not have a foreign key client_id, only project_id. I want to delete the posts in projects that have the passed client_id.  This is not working right now because no posts are deleted.


The book takes place in winter and starts off by following a young boy who just turned a certain age like 13 or in that range.  The boy notices that as he was walking back home that crows or ravens were following him and looking at him with intelligence.  As he passes each crow, it looks directly at him at caws while looking at him. The boy remarks on the strangeness but shrugs it off at first.  When the boy gets home, it is dark and there are street lights and as he is about to enter his home he feels a strange presence and turns around and some of the street lights are out and he feels someone watching him.    I don't remember much more than that in specifics. I want to say that something happens that night and the boy is rescued by a stranger who is fighting a battle with the people that were following the boy. I believe there is magic in there as well something that has to do with the seasons or night and day but i am not sure.

I read this book series as a kid back in the late 1970s, so it's an old series - and my memories are similarly old, and vague.   I know it's a fantasy series. I think there are 4 books in the series. Or perhaps 7.  There's a central boy character who has to get a collection of magical objects (every fantasy needs a quest!), each of which represents a different magical 'element': wood, stone, fire, etc. I definitely remember there was a wooden object. He lives in our normal world. The whole series takes place "here & now". I have a feeling he's a "chosen" person of some kind... But, the strongest memory I have is of a symbol: a circle which is divided into quarters (a vertical bar and a horizontal bar).  I know it's vague, but does anyone recognise this?


I can't find the solutions for this one. Basically the object are not showing up when I switch to render view ( the legs in cycles , the round base in Blender render )

Why is the selected object displaying in the 3D view, but not rendering?  In object mode, it shows up:   However, it does not show up in render mode:   Why is this so and what causes it to hide in render mode?


The solution to the quadratics is given by  $r = -\dfrac{b}{2a}\pm\sqrt{\dfrac{b^2-4ac}{4a^2}}$, which is shortened to $r = -\dfrac{b}{2a}\pm\dfrac{\sqrt{b^2-4ac}}{2a}$, but I'm wondering how if this is justified, given that $4a^2$ can be negative if $a \in \mathbb{C}$, and $\sqrt{\dfrac{x}{y}} \neq \dfrac{\sqrt{x}}{\sqrt{y}}$ if $x$ and $y$ are negative, but given that we have $a^2$, is this justified?  Is $\sqrt{x/y^2} = \sqrt{x}/y$? Is $r = -\dfrac{b}{2a}\pm\dfrac{\sqrt{b^2-4ac}}{2a}$ always true?

When deriving the quadratic equation as shown in the  () the main proof contains the step: $$ \left(x+{\frac {b}{2a}}\right)^{2}={\frac {b^{2}-4ac}{4a^{2}}} $$ the square root is taken from both sides, so why is  $$\sqrt{4a^2} = 2a$$  in the denominator and not $$ \sqrt{4a^2} = 2\left |a  \right | $$ Could somebody explain this to me? Thank you very much


I'm I missing something basic or is there no way to see the the date stamp on a pictures taken with or synced to the iPhone?

Sometimes I took a photo using my iPhone, and then later on, I wonder how long I have been there at that location, I thought of checking when the last photo was taken, and can tell the time when I arrived, but I found it wasn't easily possible to see what time the photo was taken.  Is there really a way to see the time that photo was taken, be it 1 hour and 20 minutes ago, without using any third party app and without importing the photo to a computer?  I thought this might be a simple photo info thing that might be invoked by some easy way?


For given function $g(W)$, where $W \in R^{M \times T}$. I have seen two different definition of proximal operator of it, but I don't know which one is correct ?  One with $L_2$-norm, and second one with Frobenius norm   $$prox_g(W)={arg\,min}_u(g(u) + \frac{1}{2} |||u-W||_2^2 )$$  $$prox_g(W)={arg\,min}_u(g(u) + \frac{1}{2} |||u-W||_F^2 )$$

$\newcommand{\prox}{\operatorname{prox}}$ $\newcommand{\argmin}{\operatorname{argmin}}$ $\newcommand{\dom}{\operatorname{dom}}$  Recall again that the proximal operator for vectors $\prox_{f}: R^n \rightarrow R^n$ of $f$ is defined as:  $\prox_f(v) := \argmin_{x} \left(f(x) +(1/2)\|x-v\|_2^2 \right) $,  where $f: R^n \rightarrow R \cup \infty$ is a closed proper convex function and $\|\cdot \|_2$ is the Euclidean norm. $\prox$ is strongly convex and not everywhere infinite, so there it will have a unique minimizer for every $v \in R^n$  The crucial property of proximal operator is that $x^*$ minimizes $f(x)$ iff $x^* = \prox_f(x^*)$, i.e. $x^*$ is a fixed point of $\prox_f$.  Let us consider the proof of this property. The first part, namely, that if $x^*$ minimizes $f$ then $\prox_f(x^*)=x^*$, is trivial:  $f(x) +(1/2)\|x-x^*\|_2^2 \le f(x^*) = f(x^*) +(1/2)\|x^*-x^*\|_2^2$  The second part uses the notion of subdifferential. In the proof authors say that $\tilde{x}$ minimizes  $f(x) +(1/2)\|x-v\|_2^2$  i.e. $\tilde{x} = \prox_f(v)$ iff $0 \in \partial f(\tilde{x}) + (\tilde{x}-v)$,   where the sum is of a set and a point. Recall the definition of the subdifferential:  $\partial f(x) = \{ y$ |  $ f(z)\le f(x) + y^T(z-x)$ $\forall z \in \dom{f}\}$  Take $\tilde{x}=v=x^*$, it follows that $0 \in \partial f(x^*)$ so $x^*$ minimizes $f$.  Question 1:  Consider proximal operator defined for matrices now:  $\prox_f(Y) := \argmin_{X} \left(f(X) +(1/2)\|X-Y\|^2 \right)$,  where $X$ is some real $m$ by $n$ matrix. What norm function should be taken in the definition of the $\prox$ in this case? Frobenius? Or spectral norm (induced 2nd norm) which is the largest eigenvalue (is spectral norm even differentiable?)? Or something else?  Question 2:   Can the norm for the definition of $\prox$ in case of matrices be chosen in different ways? What conditions does the proof above impose on the norm function?


I burned a live session of Linux Mint 17 Cinnamon to a USB stick. Then I installed LM17C into an external hard drive by using this USB stick. I managed to do it and even successfully started on my computer.  However I have tried to boot it on another computer, yet it did not started and gave the error below:  error: file '/boot/grub/i386-pc/normal.mod' not found. entering rescue mode... grub rescue >   My computer has an Intel processor, but the second PC has AMD. I think this is the problem. I do not know how to solve it, though.

I have been trying to install Linux Mint 16 Petra using a removable USB thumb drive on my laptop, and after multiple attempts, I get the same error every time:  error: file '/boot/grub/i386-pc/normal.mod' not found. Entering rescue mode... grub rescue>   I tried following the instructions , but absolutely none of it helped.  How do I get my computer to boot?


I tried to add driver to Sphere's RotateX and link it with Cube's LocationX.  However, as shown in the image below, the driver value is 4.651, but the Sphere RotateY is 266.    The value of the driver will be regarded as radians without permission.   I created and tried the following Expression and it worked correctly, is this method recommended by Blender?  var * (3.1415/180)

I am just trying to set up a dynamic circular array of objects. To keep it as dynamic as possible, I want to make my helpers empty z rotation driven by a driver. The Scripted Expression looks like this:  360/count while count is the count value set in the arrays modifier on my object.  The final value calculated in the driver is correct.(45 in case I have a count of 8). The actual value set in the rotation property is different. See the Screenshot below.    Am I missing something?


this time I'm writing my Bachelor Thesis on Uni Stuttgart. Now I got a Problem. I predefined my Variables for being able to change them easily in the whole dokument. For example I did it like this: \newcommand{\x}{L_i} If I now create a list of variables by \makenomenclature the variables are sorted by the command. Here \x. Is it possible to sort it by the given variables? Here L_i. It would be very nice to have a most possible easy solution for this. Thank you and sorry for my bad english.

I am sorting my nomenclature as suggested by the nomencl package documentation, but \dot{q} is being sorted before a and v, where as the desired sort is:   a \dot{q} v   The existence of a default prefix does not help, so noprefix is used. Prefixes are used to separate Roman [1] from Greek [2] variables.  \documentclass[oneside,paper=a4,fontsize=12pt,english]{scrreprt} \usepackage[noprefix]{nomencl} \makenomenclature \begin{document} \printnomenclature \nomenclature[1]{\(a\)}{Semimajor axis} \nomenclature[1]{\(v\)}{Velocity} \nomenclature[1]{\(\dot{q}\)}{Heat flux} \nomenclature[2]{\(\rho\)}{Density} % makeindex.exe Test.nlo -s nomencl.ist -o Test.nls Lorem ipsum. \end{document}   Using [1q] as a prefix causes \dot{q} to be sorted at the end of the Roman variables. How can I get nomenclature to ignore \dot{}?


<img class="tile-image clp-hover-img"              src="${product.images.medium[0].url}"              itemprop="image" data-src="${product.images.medium[0].hoverImageUrl}"/>     I am having issue with the image hover. Currently it is working fine but after ajax call, hover image won't work as expected.  After page load, when I hover on the image, new hover image loads. When I select a new product using the swatch (AJAX), then it normally shows the new image. When I hover on it, it shows the old hover image itself.  Once I hover image on the container, hover image shows. After I select a new product (color but same product), image changes normally but the hover image will be showing the same of first product color.    var tempSrc = '';  $(".clp-hover-img").hover(function(){  tempSrc = $(this).attr('src');  $(this).attr("src", $(this).data("src"));  }, function(){  $(this).attr("src",tempSrc); });

I have a bit of code where I am looping through all the select boxes on a page and binding a .hover event to them to do a bit of twiddling with their width on mouse on/off.  This happens on page ready and works just fine.  The problem I have is that any select boxes I add via Ajax or DOM after the initial loop won't have the event bound.  I have found this plugin (), but before I add another 5k to my pages with a plugin, I want to see if anyone knows a way to do this, either with jQuery directly or by another option.


Is there any difference between using '' or "" in JavaScript (example below)?   var sports = ['soccer', 'baseball', 'basketball']   or  var sports = ["soccer", "baseball", "basketball"]   This array is a super simple example, but would there any difference or cases in more advanced JavaScript where '' would make more sense than "" or vice-versa? Learning through Codecademy and they've used both interchangeably without any explanation.

console.log("double"); vs. console.log('single'); I see more and more JavaScript libraries out there using single quotes when handling strings. What are the reasons to use one over the other? I thought they're pretty much interchangeable.


minna@minna-System-Product-Name:~$ sudo apt-get updates [sudo] password for minna:  E: Invalid operation updates minna@minna-System-Product-Name:~$ sudo apt-get install updates Reading package lists... Done Building dependency tree        Reading state information... Done E: Unable to locate package updates minna@minna-System-Product-Name:~$     this is the message i got when I tried in terminal. earlier I updated from soft ware updator I get the message the upgrade needs a total of 77.7MB free space on disk'/boot' Please free atleast an additional 4.970k of disk space on'/boot'.Empty your thrash and remove temporary packages of former installations using sudo apt-get clean.this was the message .when I do that in terminal it shows that no such commands found.Then what can I do to update my system?

My /boot partition is nearly full and I get a warning every time I reboot my system. I already deleted old kernel packages (linux-headers...), actually I did that to install a newer kernel version that came with the automatic updates.  After installing that new version, the partition is nearly full again. So what else can I delete? Are there some other files associated to the old kernel images?  Here is a list of files that are on my /boot partition:  :~$ ls /boot/ abi-2.6.31-21-generic         lost+found abi-2.6.32-25-generic         memtest86+.bin abi-2.6.38-10-generic         memtest86+_multiboot.bin abi-2.6.38-11-generic         System.map-2.6.31-21-generic abi-2.6.38-12-generic         System.map-2.6.32-25-generic abi-2.6.38-8-generic          System.map-2.6.38-10-generic abi-3.0.0-12-generic          System.map-2.6.38-11-generic abi-3.0.0-13-generic          System.map-2.6.38-12-generic abi-3.0.0-14-generic          System.map-2.6.38-8-generic boot                          System.map-3.0.0-12-generic config-2.6.31-21-generic      System.map-3.0.0-13-generic config-2.6.32-25-generic      System.map-3.0.0-14-generic config-2.6.38-10-generic      vmcoreinfo-2.6.31-21-generic config-2.6.38-11-generic      vmcoreinfo-2.6.32-25-generic config-2.6.38-12-generic      vmcoreinfo-2.6.38-10-generic config-2.6.38-8-generic       vmcoreinfo-2.6.38-11-generic config-3.0.0-12-generic       vmcoreinfo-2.6.38-12-generic config-3.0.0-13-generic       vmcoreinfo-2.6.38-8-generic config-3.0.0-14-generic       vmcoreinfo-3.0.0-12-generic extlinux                      vmcoreinfo-3.0.0-13-generic grub                          vmcoreinfo-3.0.0-14-generic initrd.img-2.6.31-21-generic  vmlinuz-2.6.31-21-generic initrd.img-2.6.32-25-generic  vmlinuz-2.6.32-25-generic initrd.img-2.6.38-10-generic  vmlinuz-2.6.38-10-generic initrd.img-2.6.38-11-generic  vmlinuz-2.6.38-11-generic initrd.img-2.6.38-12-generic  vmlinuz-2.6.38-12-generic initrd.img-2.6.38-8-generic   vmlinuz-2.6.38-8-generic initrd.img-3.0.0-12-generic   vmlinuz-3.0.0-12-generic initrd.img-3.0.0-13-generic   vmlinuz-3.0.0-13-generic initrd.img-3.0.0-14-generic   vmlinuz-3.0.0-14-generic   Currently, I'm using the 3.0.0-14-generic kernel.


I am trying to add a count of 3 to this command : /execute as @a if entity @s[nbt={Inventory:[{id:"minecraft:diamond"}]}]    Edit: Some may think that this question is a duplicate, but my question is different from .    The linked question uses tellraw while this one uses an execute command. Someone might need to add a run command and /execute has this built-in.

I am using the AmazingKit plugin on my Minecraft server to make inventory kits for players. In a command block I have the following command:  /tellraw @p ["",{"text":"Iron","clickEvent":{"action":"run_command","value":"_____"}},{"text":" / "},{"text":"Gold","clickEvent":{"action":"run_command","value":"_____"}}]   Which prints the following result: Iron / Gold.  When a player clicks on Iron, what command should I write where the empty space is _____ in order to check if the player has at least (>=) 20 iron ingots in his inventory and if he/she does, remove 20 iron ingots and execute /kit Basic. If the player has less than 20 iron ingots in inventory, the command won't be executed. Instead, Insufficient amount of iron ingots will be printed out.   Same applies when a player clicks on "Gold".  I'm on 1.14 version


I'm currently learning Java, I'm just curious about the code that I wrote a minute ago, it works, but I want to know if there is a better alternative (that isn't "use the clear method").      public static void main(String[] args) {      ArrayList al = new ArrayList();      al.add("A");     al.add("B");     al.add(5);      System.out.println(al.size());      Iterator i = al.iterator();      while (i.hasNext()) {         Object next = i.next();         System.out.println("Removing " + next.toString() + "...");         al.remove(next);         i = al.iterator();     }      System.out.println(al.size()); }   Especially, because I don't really know what can be in a specific position in an ArrayList (they contains objects of every kind), I used a generic "Object next" variable. I don't know if it is acceptable.  I know that there are methods to clear an ArrayList, I just wanted to try to understand how ArrayLists works, thank you.

We all know you can't do the following because of ConcurrentModificationException:  for (Object i : l) {     if (condition(i)) {         l.remove(i);     } }   But this apparently works sometimes, but not always. Here's some specific code:  public static void main(String[] args) {     Collection<Integer> l = new ArrayList<>();      for (int i = 0; i < 10; ++i) {         l.add(4);         l.add(5);         l.add(6);     }      for (int i : l) {         if (i == 5) {             l.remove(i);         }     }      System.out.println(l); }   This, of course, results in:  Exception in thread "main" java.util.ConcurrentModificationException   Even though multiple threads aren't doing it. Anyway.  What's the best solution to this problem? How can I remove an item from the collection in a loop without throwing this exception?  I'm also using an arbitrary Collection here, not necessarily an ArrayList, so you can't rely on get.


I am a US citizen traveling from Kathmandu to US through Istanbul, Turkey. I have a 19 hour layover in Istanbul. Can I visit the area near the airport or stay in a near-by hotel while in transit? Are there visa requirements to leave and re-enter the airport during this 19 hour layover?

I will be staying over for 20 hour layover and I was wondering if I needed to get a visa in order to leave airport and visit the city. And if I need a visa do I apply for it while I'm on the layover in Istanbul or can I apply for it in America before I go?


Java contains many built in classes. I seeked someof them in the Java API documentation but I couldnt see or find the body of these classes and their related methods.  For example when I seeked the clearRect method of the graphics glass I found just the informations as follows without much details.  > public abstract void clearRect(int x, >              int y, >              int width, >              int height)   Clears the specified rectangle by filling it with the background color of the current drawing surface. This     operation does not use the current paint mode. Beginning with Java   1.1, the background color of offscreen images may be system dependent. Applications should use setColor followed by fillRect to ensure that   an offscreen image is cleared to a specific color.      Parameters: x - the x coordinate of the rectangle to clear. y - the y   coordinate of the rectangle to clear. width - the width of the   rectangle to clear. height - the height of the rectangle to clear. See   Also: fillRect(int, int, int, int), drawRect(int, int, int, int),   setColor(java.awt.Color), setPaintMode(), setXORMode(java.awt.Color)   Is there any way to find the source code of these classes ? Or are they hidden by the constructors of Java for some reasons ?

I want to have a look at how Java implements LinkedList. Where should I go to look at the source code?


I don't know how to make this code safe. I tried to use mysql_real_escape_string in the query variable like     $query = "select * from products where id= " . mysql_real_escape_string($products);    but didn't work, also tried to escape in the products variable, but got the same result. Any sugestions? Thanks.    <?php  / Define vars. $conn = mysql_connect('localhost', 'test', 'test'); $products = isset($_GET["products"]) ? $_GET["products"] : ""; $query = "select * from products where id=$products";  // List elements. if ($conn) {  mysql_select_db('testsqli');  $result = mysql_query($query);    // Table head.  echo '
';  echo '
';  echo 'Description	';  echo 'Price	';  echo '
';    // Empty table?  if (@mysql_num_rows($result)==0)  {   echo '
';   echo 'That\'s all!	';   echo '
';  }   // Listing data in table.   while ($row = @mysql_fetch_array($result))   {    echo ''.$row['Description'].'	';;    echo ''.$row['Price'].'	';;       }  echo '
'; } ?>

If user input is inserted without modification into an SQL query, then the application becomes vulnerable to , like in the following example:  $unsafe_variable = $_POST['user_input'];   mysql_query("INSERT INTO `table` (`column`) VALUES ('$unsafe_variable')");   That's because the user can input something like value'); DROP TABLE table;--, and the query becomes:  INSERT INTO `table` (`column`) VALUES('value'); DROP TABLE table;--')   What can be done to prevent this from happening?


I have a Logitech Headset that uses MS Supplied drivers, in this case Generic USBAudio Driver. The sound is really choppy in a 64bit version of Win 7. 32Bit works perfectly fine.   How is it possible for me to notify MS, and get the problem fixed?

I have come across an issue that I feel is a  in Windows 7. What is the official process for submitting an issue to Microsoft from a consumers perspective as an end user of Windows?


Why does method return true if I change the value of r to false in finally?      boolean myMethod() {     boolean r = true;     try {         throw new Exception("");     } catch (Exception e) {         return r;     } finally {         //System.out.println("executing finally");// will print if we uncomment this line         r = false;     } }

Considering this code, can I be absolutely sure that the finally block always executes, no matter what something() is?  try {       something();       return success;   }   catch (Exception e) {        return failure;   }   finally {       System.out.println("I don't know if this will get printed out"); }


How and why should users vote on answers?  This explains how to accept an answer:

I have seen a few  here on Meta Stack Exchange that cover parts of this, but they are often too local, and none of them seem to cover all the relevant scenarios.  I will break it up into multiple parts in order to make this more specific:     When should I vote on a question:   What are the qualifications for a question to be deserving of being up-voted? When shouldn't I vote up on a question? What are the things that would cause a question to need to be down-voted?   How should I go about down-voting the question (do I wait a little while to give the OP a chance to change it, or do I down-vote it immediately)?  When shouldn't I vote down on a question?  When should I vote on an answer:   What are the qualifications for an answer to be deserving of being up-voted? When shouldn't I vote up on an answer? What are the thing that would cause an answer to need to be down-voted?   How should I go about down-voting the answer (do I wait a little while to give the OP a chance to change it, or do I down-vote it immediately)?  When shouldn't I vote down on an answer?  When should I vote on a comment:   While votes on comments do not affect reputation points, it might be useful to new users to know when to up-vote them.    It seems that a full, comprehensive list of these would be invaluable to new users looking to figure out how the voting system works, but this list seems to be missing from the meta site.


Looking at this page:  There is a line that says "Profitable in 10 Months 14 Days", I wanted to pull the "10 Months 14 Days" to a Google Sheet. When I inspect the HTML code, this is what came up:  so I used this: =IMPORTXML("https://www.mycryptobuddy.com/BitcoinMiningCalculator/path?hashrate=110&powerCost=0.059&power=3250&hardwareCost=4050", "//div//h4//b[class='ng-binding']")  But it is not working unfortunately. I spent hours trying to figure it out and changing it and I managed to pull different things. Any ideas? Edit 1: I saw the answers before my question was migrated and I cannot see them again after migration. Thank you to the people that took the time to explain to me. I tried disabling Java and the content I am looking to import into sheets did not disappear: I tried HTML variations with no luck so I edited the IMPORTXML code to this: `=IMPORTXML("https://www.mycryptobuddy.com/BitcoinMiningCalculator/path?hashrate=110&powerCost=0.059&power=3250&hardwareCost=4050", "//div//h4//b")`  Which led to this import into Google Sheets (not N/A) : {{breakeven | breakevenFilter}} Is it time to give up or am I one step away from getting what I'm trying to do?

Google Sheets has several import functions   IMPORTDATA IMPORTFEED IMPORTHTML IMPORTXML   Sometimes the above functions returns errors like #N/A Imported content is empty and would like to be sure that there isn't a problem with the resource content to be imported.  How do I know if these functions are able to get the content that I looking to import?  I know that there also exist IMPORTRANGE but that function only is able to import content from Google Sheets spreadsheets


Let's say we have the following signature  void doSomething(string s)   When the user calls the function, they can call  doSomething("hello") or doSomething("\x15\x3C\xFF")  Is there a way to tell when the argument is the second form, a hexadecimal value?  I want to do something like  if(isHex(s))          // do this else     // do that

What is the most efficient way in C# 2.0 to check each character in a string and return true if they are all valid hexadecimal characters and false otherwise? Example void Test() {     OnlyHexInString("123ABC"); // Returns true     OnlyHexInString("123def"); // Returns true     OnlyHexInString("123g"); // Returns false }  bool OnlyHexInString(string text) {     // Most efficient algorithm to check each digit in C# 2.0 goes here }


When people say that general relativity predicts gravitational waves, how so?

It is well known that general relativity predicts gravitational waves, but I would like to know how. What solution(s) to the Einstein field equations yield something which can be interpreted as a wave(-like) phenomenon?


Given a fairly simple regex, I'd like to match a text between to delimiters:  ___MANUAL_TICKET___  ###_CLIENT_START_### TEST ###_CLIENT_END_###  ###_PROBLEM_START_### TEST2 ###_PROBLEM_END_###  ###_EMAIL_START_### xyz@test.com ###_EMAIL_END_###   To get the client I am using this regex:      ###_CLIENT_START_###\s(.*?)\s###_CLIENT_END_###   which works as seen .  But when I use it in my PHP Code it does not find any matches:  preg_match('@###_CLIENT_START_###\s(.*?)\s###_CLIENT_END_###@', $source, $matches);  (tried different regex delimiter such as / and ~, same result)  What am I doing wrong?

For example, this regex  (.*)<FooBar>   will match:  abcde<FooBar>   But how do I get it to match across multiple lines?  abcde fghij<FooBar>


Any idea why git hash-object has different outcome from shasum and openssl commands ?   ➜ printf test | shasum a94a8fe5ccb19ba61c4c0873d391e987982fbbd3  -  ➜  printf test | git hash-object --stdin 30d74d258442c7c65512eafab474568dd706c430  ➜  echo -n "test" | shasum a94a8fe5ccb19ba61c4c0873d391e987982fbbd3  -

As I understand it when Git assigns a SHA1 hash to a file this SHA1 is unique to the file based on its contents.   As a result if a file moves from one repository to another the SHA1 for the file remains the same as its contents have not changed.   How does Git calculate the SHA1 digest? Does it do it on the full uncompressed file contents?   I would like to emulate assigning SHA1's outside of Git.


I am finding the number of homomorphisms $f:S_3 \to S_3$ when $\ker(f)=(1)$.  By first isomorphism theorem, $$S_3/Ker(f)=S_3/(1) \simeq f(S_3)\subset S_3.$$i.e, $f:S_3 \to S_3$in this case. Now any element $x \in S_3$ goes to $f(x) \in f(S_3)=S_3$.  Also $O(f(x)) |O(x)$.   The $identity$ permutation  $(1)$ maps to $(1)$ as $1|1$;  order $2$ elements maps to order $2$ elements, i.,e., $\{(12),(13),(23) \} \to \{(12),(13),(23) \}$ in $3!=6$ ways.   But the problem occurs with the order $3$ elements, $(132)$ and $(123)$.   We can have $f((123))=(123)$ or $f((123))=(132)$  and $f((132))=(132)$ or $f((132))=(132)$.  So here total $2!$ ways.  Hence total $6 \times 2=12$ homomorphisms  from $S_3 \to S_3$  if $\ker(f)=(1)$.  Is it true?    Edit:  Why  we cannot get $f((123))=(132)$ or $f((132))=(123)$ ?

What is the number of automorphisms (including identity) for permutation group $S_3$ on 3 letters?  I believe the answer for this is 6. As we can write the group elements as below   (a)(b)(C) (ab)(c) (ac)(b) (bc)(a) (abc) (bac)   Can we generalize that for any $S_n$ onto $n$ the number of automorphisms will be $n!$ Also I cannot find this anywhere in my text, can we have a permutation $S_n$ onto $m$ where $n\neq m$? (for eg: is it possible to have a permutation group say $S_5$ on say 2 elements?)


I'm quite new at doing full-time research as a career. It seems that everyone in my department whom I talk with is focused not only on "their" research but also on various side projects with other researchers — Including people who are newer than I am. What am I not doing which they are? — I don't want to simply go to everyone I meet and ask "what exactly are you doing, and do you need help with it?" (it sounds rather artificial/forced/desperate/etc.).  This is related to , but if I don't even know whom to approach, then the answers to that question are not very useful.

This question is quite premature for the current state of my studies, but I already have a few people in mind to which this question applies.  In Academia, would it be considered normal to approach a researcher you respect (who's work has great personal value or interest to you) and suggest that you would be interested in assisting with their future research efforts? In this case, I'm speaking less about full collaboration/co-authorship, and more about being willing to assist with the 'grunt work' of a given research project, purely out of interest in the subject matter.  Would this be construed as insulting to the researcher?  Is this sort of offer commonplace?  Is there an expectation of credential equality in this situation? For example, would it be inappropriate for an Undergraduate student to make such an offer to a PhD?


I have very long trigonometric formulas in latex. I want to print only s instead of printing complete sin in the latex document. same for the cos. Is there any way ?

How can we make First letter Capital while using trigonometric functions. eg: \cos (60^\circ) gives simple cos (all in small). What is needed is 'Cos' (with initial capital). For italics in mactex i used \it but it didn't italicized 'cos' only the number '60'. So how to do that?


I just started using Ubuntu a few days ago, and only gave it 25 GB of space. Now that I look back at it, I should of put 300 GB or more. Is there a way to add more space to my root directory? Or should I just do a backup, reformat a partition, then build off a backup? Or is there a better way? Big noobie here I'm sorry.

Previously, I have installed Windows 7 on my 320 GB laptop with three partitions 173, 84 and 63 GB each. The 63 GB partition was where the Windows was installed. The rest were for file containers.  Now I changed my OS to Ubuntu 12.04 LTS. I installed Ubuntu by replacing the entire Windows 7 on the 63 GB partition. The rest of the partitions remain as an NTFS Windows partition and I can still access them both (the 173 and 84 GB partitions).  Now I want to change the two partitions of Windows into an Ubuntu format partitions plus most importantly, I want to extend the 63 GB partition to more than a 100 GB because at the moment I am running out of disk space. Whenever I try to install any application, especially using wine, it always complains for a shortage of disk space.  How do I do the extending activity before I entirely format my laptop again and lose all the important files on my partitions?


I have problems with sending email with phpmailer in hotmail accounts. There are some answers here in stack overflow but none of them can solve my problem. I have the same smtp user and from, i do not include 'spam phrases' etc.. here is the code:  require 'phpmailer/PHPMailerAutoload.php';       $mail = new PHPMailer;   $mail->isSMTP(); $mail->Host = 'localhost';  $mail->SMTPAuth = true;                                 $mail->Username = 'xx@kk.com'; // SMTP username                  $mail->Password = 'yy'; // SMTP password $mail->setFrom("xx@kk.com"); $mail->addAddress(zz);                $mail->isHTML(true);                                 $mail->Subject = "sub"; $mail->Body     = "<!DOCTYPE html>"; $mail->Body    .= ""; $mail->Body    .= ""; $mail->Body    .= "
Thank you for using the Model. Your code is:
"; $mail->Body    .= "
FB-".$x."X".$z."X".$y1."X".$y2."-".$kind."-H".$y3."
"; $mail->Body .= "
ForenBox: ". $kind2; $mail->Body .= "
Long sides: ".$x."mm"; $mail->Body .= "
Height of Long sides: ".$y1."mm"; $mail->Body .= "
Short sides: ".$z."mm"; $mail->Body .= "
Height of Short sides: ".$y2."mm"; $mail->Body .= "
Height of Corners: ".$y3."mm
"; $mail->Body    .= ""; $mail->Body    .= ""; $mail->send();   Thanks!

This is a tricky one and I've always relied on techniques, such as permission-based emails (i.e. only sending to people you have permission to send to) and not using blatantly spamish terminology.  Of late, some of the emails I send out programmatically have started being shuffled into people's spam folder automatically and I'm wondering what I can do about it.  This is despite the fact that these particular emails are not ones that humans would mark as spam, specifically, they are emails that contain license keys that people have paid good money for, so I don't think they're going to consider them spam  I figure this is a big topic in which I am essentially an ignorant simpleton.


I need to extract the Lat/long coordinates of the centroids of districts. My QGIS project SCR and the different layers have all been set on "WGS 84 / UTM zone 18N".   I've created the centroids using the usual tool. I could then extracted the coordinates using the "Vector > Geometry Tools > Export/Add Geometry Columns", or saving the layer in CSV typing "GEOMETRY=AS_XY" in the "Layers" part of the "OGR creation options".  Nevertheless, both methods output Cartesian coordinates, whereas I need Lat/long coordinates.

How do I easily calculate the lat/long of points using the QGIS Field Calculator? I saw a previous related question (), but it deals with a more advanced approach. In ArcGIS Desktop this is similar to the Calculate Geometry function; I just can't find where do this in QGIS.


Need help how to calculate the analysis of an algorithm  I understand the concept of Big O and know the difference between the types of cases there are.  public int examplecode(int[] data) {     int n = 0;     int counter = data[0];      for(int j = 1; j < n; j++)     {         if(data[j] > counter)             counter++;     }      if(data[j] > counter)         counter++;      for(int j = 1; j < n; j++)     {         for(int k = 1; k < n; k++)         {             if(data[k] > counter)                 counter++;             counter += 3;         }     }      return n; }   I expect n^2 + 9n

Most people with a degree in CS will certainly know what . It helps us to measure how well an algorithm scales.   But I'm curious, how do you calculate or approximate the complexity of your algorithms?


When a user see a list of  Linked/Related Questions on right panel, it will be useful to have the word [duplicate] visible immediately after title. It will help to understand why the questions linked and should I look at them.   Note that if the question has too many links, there is a link at the bottom "see more linked questions" and it opens full size page, where [duplicate] status is shown after the title of each duplicate question. So the change will make linked questions presentation consistent.  Somehow related suggestions to make easier see duplicates: .

I saw a question on Meta that was obviously going to be a duplicate:        And indeed, looking at the "Related" questions list for that question showed a number of duplicates:    Being the good citizen I am, I tried to vote to close (technically Flag as duplicate as I've not got the rep here to vote to close) it as an Exact Duplicate only to find myself falling into a rabbit hole of Closed, Duplicate questions. Is there any way to flag a closed question as such in the Related list?  Mostly because the first one I picked was closed as a duplicate of the second one, which was closed as a duplicate of the one that is now listed as the duplicate/linked answer.   Edit to respond to comment:  I take the point about "not voting to close on title alone", and normally wouldn't, however as the questions had identical titles, and it's pretty clear what they should be asking, I clicked the first one:    which lead to:  which leads to:  - but I'd got bored following links and didn't check that one as the first two were identical, so assumed this was too and didn't want to see how deep the rabbit hole led.   In the related list, there's only one other question in there that is an exact duplicate, but hasn't (currently) been closed as such which is:      Reasoning for highlighting closed questions:  The "Questions with similar titles" does display the closed titles when asking the question, so it should be fairly possible to include.  If there are clearly duplicate titles, then as a reader/reviewer would be helpful to know which ones are already closed as duplicates so you can either:   Use the remaining open questions to focus on which of those is the canonical answer to close this with. Use the closed questions to find the canonical answer (which failed for me with my route of clicks).


I have  and want to install any version of Ubuntu on it, but I don't have an idea how. You have ubuntu for mobile phone, but I don't know where to start. I search internet, but no success.  If there is some way to install Android or something else, I'll try it. Phone is not so old, serves me fine but I need many of new options like Viber, maps etc.

With the announcement of the Ubuntu Phone OS I'd like to know what phone (and tablet) models are supported at this time.  Note from foss & Oli: We are making this the master question for all future "Will this work on <insert random tablet/phone/device here>?!" questions


I've recently spent some time finding the cheapest fares for my journey and that got me thinking.  Essentially I'm traveling UK <-> Tallinn (Estonia) anytime within the next 4 months for a week. But I'm not bothered travelling through other airports or countries if that makes my journey cheaper (and as a EU citizen with no checked in luggage all the transfers shouldn't be a big hassle).  So currently if I search for MAN <-> TLL in flights.google.com that gives me the cheapest return for the end of May for about £190 with transfers (that's only because I've already bought my tickets so using end of May as an example to compare prices).  I live near Manchester but if I buy my tickets in advance (which I usually try to do) it doesn't matter if I fly from Manchester Airport, Edinburgh Airport, any airport in London or possibly anywhere from in the UK. Although it's less hassle to get back home from Manchester Airport - any airport in the UK presumably is fine for me as long as it's cheap (just an example to prove what I mean: I've spent £16.50 for the train ticket to get from Lancashire to Stansted Airport (London) and £14.05 to get from Manchester Airport back home, so there really is no big difference in price).  And if I choose London (all airports) <-> TLL that gives me around £100 for a direct return.  So currently I have purchased the following tickets: STN->TLL (£36.71), TLL->DUB (~£23.84), DUB->MAN (~£7.94). So that's about £69 in total for a "return". And I could have reduced that price even more (by buying STN->RYG (£13) & RYG->TLL (£12) instead of a direct one but I got a direct one because that one was better for me for that specific day only), or also had an option to fly MAN->DUB, DUB->TLL that would be again cheaper than my direct flight STN->TLL.  So the question is: I can of course find these routes and prices manually but it will take me days to look up every possible route between the UK and Tallinn (Estonia) and compare all the possible prices to narrow it down to 1-5 cheap options to choose from. I've used flights.google.com and skyscanner.net (and possibly some other ones) but none of them are able to find these cheap rotes that I can find manually (which is disappointing). Is there any website-software-anything that can find the cheapest tickets with layovers/transfers through other airports/countries from a country that I choose (for example the UK) to a country/city/airport (for example Estonia or Tallinn or TLL)?  P.S. Sorry for the long question but I had to provide my example to make it clear that the usual websites doesn't seem to find what I want to find.  EDIT1: Although broad searching is one aspect of my question, the most important one is actually finding the cheap connections automatically. Google or Skyscanner didn't see the possibility of flying cheaper like MAN->DUB->TLL or STN->RYG->TLL,  the only cheap option it knows about is the direct flight STN->TLL with Ryanair, although somehow the more expensive flights that it finds are with connections, so it can find flights with connections just not the cheap ones!  EDIT2: I've accepted Tor-Einar Jarnbjo's answer that explains why I couldn't find these cheap flights but if anyone knows a website that can still find these cheap flights please let me know! I accept all the risks!  EDIT3: As it was found out this question is a duplicate of  , although that original question was only answered because I've asked mine. :)

There are often situations where buying two separate one-way tickets from A to C via B is cheaper than buying a normal multi-leg ticket. This can be especially useful with airlines such as Ryanair, which specifically avoids selling multi-leg tickets.  Is there a search engine which allows one to search for such flights?


Today I opened my Ubuntu and I saw    What should I do ?

This is what I've got. I cannot boot and I see the two of three little lights on the keyboard blinking all the time and the cooling is working on full power, almost.  I saw in other askubuntu topic suggestion for memory test. I did it. I didn't have any errors.  I am 99,9% sure it is not a hardware problem, because I have Windows 7 and I can boot it and it works just fine.  This problem came without any warning or something. I just turned off the laptop one day and at the other day I couldn't boot.   From recovery mode I get this:


I am sorry if my question is too simple, but I am a bit of a beginner on tension. So this is the problem:  A system of two objects suspended over a pulley by a flexible cable is sometimes referred to as an Atwood’s machine. Here, let the mass of the counterweight be 1000 kg. Assume the mass of the empty elevator is 850 kg, and its mass when carrying four passengers is 1150 kg. For the latter case calculate (a) the acceleration of the elevator and (b) the tension in the cable.  So they call: $$m_E = 1150kg$$ $$m_C = 1000kg$$  Now what I don't understand from the explanation I was given is that the tension force and acceleration for both objects is the same in this example.     We leave the motor out of the system for this calculation, and assume the cable’s mass is negligible and the pulley is frictionless and massless, which assures that the “tension” in the cord has the same magnitude on both sides of the pulley.   How can tension force be the same if tension force is the weight plus the net force, and if the weight is different for both objects, then how is the tension and acceleration the same magnitude on both objects?

I'm going to provide my argument for why I think the tension in a rope should be twice the force exerted on either side of it.  First, let's consider a different example. Say, there is a person named A and a block in space. A pushes on the block with a force of 100 N. Then, the block will also push A with a force of 100 N by Newton's third law. Now, consider the case where instead of the block, there is a person B who is also pushing on A with a force of 100 N while A is pushing on him. A will experience a force of 100 N because he pushed on B, AND another 100 N because he is being pushed by B. Hence he will experience a force of 200 N. Similarly, B also experiences 200 N of force.  Now, back to the original problem. There are two people A and B in space with a taut rope (no tension currently) in between them. If only A is pulling and B is not, then I agree that the tension is equal to the force A exerts. This situation (in my opinion) becomes analogous to the above if B is also pulling. So, say both of them pull from either side with a force of 100 N. Then the rope at the end of B will pull B with a force of 100 N (this pull is caused by A). By Newton's third law, the rope will experience a pull of 100 N. But B is also pulling his end of the rope with 100 N. Therefore, the tension should be 200 N. Similarly, the end of the rope at A must pull A with 100 N of force (because B is pulling from the other side) and hence experience a force of 100 N itself by Newton's third law plus another 100 N because A is pulling on the rope.  Apparently, the answer is not this (according to my searching on the web). So, could anyone tell me why this reasoning is wrong? Thanks.  EDIT : So apparently people don't agree with my first example, leave alone the second. This is to the downvoters and the upvoters of the highest-rated answer: You all agree that if only A pushes B with a force of 100 N, then A and B both will get pushed by a force of 100 N in opposite directions, right? Then, in the case where B is also pushing with a force of 100 N, it doesn't make sense that the answer would be exactly the same. It doesn't seem right that no matter what B does, B and A will always experience the same force as they would have if B hadn't applied any force.  EDIT 2 : I'm going to provide here a link to a question that I posted:  According to the answer and the comments there, the reason as to why my first example is incorrect is different to the one provided here. So maybe you should all read the answer and the comments provided by the person and reconsider what you think.


I have a question about the structure of the QED lagrangian, in particular the free photon lagrangian which is contained in it. My premise is: I only know how to exploit canonical quantization in order to quantize a theory; I don't know how to use the path integral formulation.  The QED lagrangian is: $$ \mathcal{L}=-\frac{1}{4}F^{\mu \nu}F_{\mu \nu}+\bar{\psi}(i\gamma^{\mu}D_{\mu}-m)\psi, $$ so I assume that the free photon theory exploited here is  $$ \mathcal{L_{free}}=-\frac{1}{4}F^{\mu \nu}F_{\mu \nu}. $$ However, I also learnt that $\mathcal{L_{free}}$ jointed with Lorenz's gauge cannot give us a covariant quantization for the electromagnetic field (by means of the canonical quantization, at least). In fact, we introduce the following lagrangian: $$ \mathcal{L_{feyn}}=-\frac{1}{4}F^{\mu \nu}F_{\mu \nu}-\frac{1}{2 \xi}(\partial_{\mu}A^{\mu})^2 $$ with Feynman gauge choice $\xi=1$. This, jointed with Gupta-Bleuer constraint, gives us the physical states of the electromagnetism.  So: why do we adopt $\mathcal{L_{free}}$ instead of $\mathcal{L_{feyn}}$? I know that the latter is not gauge-invariant, but the covariant quantization of the theory is achieved through that, so this point is not clear to me.

In my quantum field theory class we have been told to use this Lagrangian for the photon field  $$\mathcal{L}=-\frac{1}{4}F_{\alpha\beta}F^{\alpha\beta} -\frac{1}{2}(\partial_{\rho}A^{\rho})^2.$$  but the reasons have been kept quite obscure. Why do we do this? We don't we stick with the good old Maxwell Lagrangian? Doesn't this extra term change things? and if not (as I suppose it is) why not?


Prove that $\sqrt[3]{2} + \sqrt[3]{4}$ is irrational. My steps so far: I found that the polynomial $y^3-6y-6=0$ has roots $\sqrt[3]{2} + \sqrt[3]{4}.$ Can I use this to prove that $\sqrt[3]{2} + \sqrt[3]{4}$ is irrational? If so, how? I was thinking of using Proof by Contradiction, but I'm not so sure.

So while doing all sorts of proving and disproving statements regarding irrational numbers, I ran into this one and it quite stumped me:  Prove that $\sqrt[3]{2} + \sqrt[3]{4}$ is irrational.  I tried all the usual suspects like playing with $\sqrt[3]{2} + \sqrt[3]{4} = \frac{a}{b}$ for $a,b\in \mathbb{Z}$ , but got nowhere.  I also figured maybe I should play with it this way:  $2^\frac{1}{3} + 4^\frac{1}{3}=2^\frac{1}{3} + (2^2)^\frac{1}{3}=2^\frac{1}{3} + 2^\frac{2}{3}=2^\frac{1}{3} + 2^\frac{1}{3}\times 2^\frac{1}{3}=2^\frac{1}{3}(1+2^\frac{1}{3})$  But there I got stumped again, because while $1+2^\frac{1}{3}$ is irrational, nothing promises me that $2^\frac{1}{3} \times (1+2^\frac{1}{3})$ is irrational, and I feel like trying to go further down this road is moot.  So what am I missing (other than sleep and food)? What route should I take to  prove this? Thanks in advance!


I want to know if this is possbile  arr1 = [{   text: "John",   Description: "tall" }, {   text: "Dave",   Description: "short" }, {   text: "Christian",   Description: "medium" }, {   text: "Mark",   Description: "thin" }]  arr2 = [{   text2: "Orange",   Description2: "sweet" }, {   text2: "Prunes",   Description2: "Bitter" }, {   text2: "Apple",   Description2: "sweet" }]   I want to merge the two arrays to look like this  arr3 = [{   text: "John",   Description: "tall",   text2: "Orange",   Description2: "sweet" }, {   text: "Dave",   Description: "short",   text2: "Prunes",   Description2: "Bitter" }, {   text: "Christian",   Description: "medium",   text2: "Apple",   Description2: "sweet" }, {   text: "Mark",   Description: "thin" }]   I have tried to use concat() but it only puts the merge object at the end of the first array it does not seem to give the output that I want.

I need to be able to merge two (very simple) JavaScript objects at runtime.  For example I'd like to:  var obj1 = { food: 'pizza', car: 'ford' } var obj2 = { animal: 'dog' }  obj1.merge(obj2);  //obj1 now has three properties: food, car, and animal   Does anyone have a script for this or know of a built in way to do this?  I do not need recursion, and I do not need to merge functions, just methods on flat objects.


Is there a simple characterization of integral quadratic forms that represent the same numbers?  I know that if two quadratic forms are in the same $GL_n(\mathbb{Z})$-orbit then they represent the same numbers - are there forms in different such orbits that represent the same sets of integers?  Thanks!

I am currently working with quadratic forms for a given discriminant D; to get all primitive forms (one for each equivalence class) I found this website :   For instance for the case D=-23, the three primitive forms are given by : (1,1,6), (2,1,3), (2,-1,3); and I know that the two last ones represent the same integers.  I need now to work with some discriminant such that the class number is larger (h(D)=4,5..) and I need to know if two forms represent the same integers. Would you know of a similar software where I can check this?  Thanks.


I have a tar archive foo.tar.gz, inside of which a directory containing another directory contains a file: folder_1/folder_2/file.txt.  I want to untar file.txt  without extracting folder_1/folder_2/.  Using  tar -xvf foo.tar.gz folder_1/folder_2/file.txt   I get file.txt inside the subdirectories that contained it inside the tar archive (folder_1/folder_2/file.txt).  Is there a way of getting only file.txt and nothing else in a single command, avoiding extracting everything?

I have a tar.gz file from which I have to extract only the files in current directory without creating the whole structure.  For example:    tar.gz contains below files,    /u01/app/oracle/file1 .. .. /u01/app/oracle/file10 /u01/testdata/file1 .. .. /u01/testdata/file5   the tar.gz is present in /u02. So when extracting I want file1 through file10 coming under /u02 instead, the whole directory structure is getting created under /u02


Let $\mathcal{l}_\mathbb{R}^\infty$ be the space of bounded sequences in $\mathbb{R}$. We define a map $p: \mathcal{l}_\mathbb{R}^\infty\to\mathbb{R}$ by $$p(\underline x)=\limsup_{n\to\infty} \frac{1}{n}\sum_{k=1}^n x_k.$$ My notes claim that $$\liminf_{n\to\infty} x_n\le p(\underline x)\le \limsup_{n\to\infty} x_n.$$ I haven't found a neat way to show that this holds (only a rather complicated argument). Is there an easy, intuitive way ?

This is a question from the book Methods of Real Analysis by R. R. Goldberg.     If $(s_n)$ is a sequence of real numbers and if $$\sigma_n=\frac{s_1+s_2+\cdots+s_n}{n}$$ then prove that: $\operatorname{{lim sup}}\sigma_n \leq \operatorname{lim sup} s_n$.   I don't have any idea how to start working on this problem. Please help. Thanks.


Is it okay to delete the comma after '1969' below ?  Joe said, "February 7, 1969[,]is my date of birth."   And can we delete the comma after 'Indiana' and '2015' below?  Lisa reported, "The Gary, Indiana[,] man was arrested on charges of conspiracy."  Johnson said, "The February 1, 2015[,] meeting has been canceled."  After all, '1969', 'Indiana' and '2015' are all essential information and are not parenthetical elements; hence those commas should be removed, right?  Thank you.

Despite the advice of style guides (they're just an opinion), would you omit the comma after "New Jersey" in this example as I have done?  Please, no recasts.     The Elizabeth, New Jersey rock band cut its first CD last month.   In a full date adjective, would you omit the comma after "1999" as I did below?     The June 6, 1999 issue of Billboard Magazine sold like hot cakes.   Lastly, can we omit the comma, as I did, after "1964" below?     November 6, 1964 is my birthdate.


I would like to install Office 2015/365 on Ubuntu 15.04. I tried to install Office using Wine, but that did not work. Please note that I do not want virtualisation unless it has a -like behaviour, where application windows are treated like regular Ubuntu application windows by the system.

I am trying to install Microsoft Office 2013 on Ubuntu 12.04 LTS (32-bit). I have downloaded an iso file of said product and installed wine1.4-i386 using the apt-get command on the terminal.  The question is I don't know the steps how to install it. I can't get much tutorials on Internet how MSOffice2013 can be installed on Ubuntu.  If any versions of wine isn't an option, what other options can be used to run Microsoft Office 2013?


I'm deciding on whether to spend the money to upgrade my RAM or add an SSD to my Macbook Pro.  Here's the stats...   Early 2011 MacBookPro8,1 i7 2.7Ghz 8G RAM STBD1000400 Seagate Hybrid 1TB drive   I could spend about $130 on either...   16G RAM 250G Samsung EVO 850 SSD (replacing the DVD drive)   The machine is mostly used for coding, compiling, web browsing, watching movies and listening to music.  It is rarely CPU bound.  The OS and applications and home directories should fit easily into 250 gigs with my media going onto the 1TB drive.  Thoughts?

I am asking myself which constellation is better: should I stock up my RAM up to 16GB (from 8GB), or should I buy a SSD with 128GB??   I really dont know :/  Cheers!  BTW: My macbook supports 16GB RAM, i already checked this ;)


I would like to install a command line tool within a Docker image in order to quickly convert *html files into *pdf files.   I am surprised there is not a Unix tool to do something like this.

How can I convert a html book (consisting of a number of html files linked to each other) to a pdf file on Ubuntu?   Hope the resulting pdf file can have bookmarks according to the structures of the html book.  The html book can be downloaded from . Extract it, and go to help, and the directory manual is the html book.


According to expiration date in the package it only takes a week. Maybe it can keep for longer?

How do I know if a given food or ingredient I have is still good, or if I should discard it?  How can I best preserve a food or ingredient?     This broad question is intended as a "general reference" question to quickly answer many how long will food keep for? questions. Please feel free to edit this question to expand and clarify as needed.


I'm loading some stuff from a php page using AJAX. this works fine.  but now I need to get the elements (button or form or div) loaded using AJAX.  My current code that doesn't work is this:  jQuery(document).ready(function() {   $(function(){        $('.delForm').on('submit', function(dleItem){           // prevent native form submission here         dleItem.preventDefault();          // now do whatever you want here           $.ajax({             type: $(this).attr('method'),// <-- get method of form             url: $(this).attr('action'),             //url: "cart.php",             data: $(this).serialize(), // <-- serialize all fields into a string that is ready to be posted to your PHP file             beforeSend: function(){              },             success: function(data){              }         });     });       });   });   I tried to do something like this:  document($('.delForm')).on('submit', function(dleItem){   and this:   body($('.delForm')).on('submit', function(dleItem){   but this will stop my code working.  could someone please advise on this issue?  Thanks in advance.

I have a bit of code where I am looping through all the select boxes on a page and binding a .hover event to them to do a bit of twiddling with their width on mouse on/off.  This happens on page ready and works just fine.  The problem I have is that any select boxes I add via Ajax or DOM after the initial loop won't have the event bound.  I have found this plugin (), but before I add another 5k to my pages with a plugin, I want to see if anyone knows a way to do this, either with jQuery directly or by another option.


I was following a tutorial video on YouTube on how to make a coffee cup, but in the middle of doing so I accidentally changed which type of selection I was using. For example I can usually drag a rectangle over object and it will select the faces, but now it's a circle and I have to run it over each face individually. I've tried googling the answer but nothing that I found has worked. Does anyone know how to get out of this?

I was editing a curve for hair, and pressed W to bring the specials menu and Subdivide it, but instead everything but the curve I had active dissapeared, and my cursor turned into a circle like the one from the circle select mode.  I'm guessing they changed the specials menu and I'm inside some unknown to me function, but I'm not sure how to turn everything back to normal.


I wanted to do the sigma enclosures in the below shown equation correctly. Actually this is also expectation symbol, right? I don't know it's name.

I know what my symbol or character looks like, but I don't know what the command is or which math alphabet it came from. How do I go about finding this out?