I'm not sure if it exists or not, but does Stack Exchange have a site for asking psychology questions? And if not, is it possible to create one?
I am new to Stack Exchange. I know there is a lot of discussion sites for Stack Exchange. I would like to know about there were any Stack Exchange site available for discussing and solving personal psychological problems.
How to solve a difference equation? So I have the difference equation $4y_{k+1} = 2y_k$.  I need to solve this equation, first with the initial condition $y_0 = 0$ and then with the initial condition $y_0 = 2$.  The professor wrote on the answer sheet that applying iteratively the recurrence relation it is easy to check that:  $y_k= (1/2)^k y_0 $.  Since I missed the lecture where he explained this, can somebody explain how to come about with this question?  I imagine that once I get the equation, then the initial condition $y_0 = 0$ gives us the particular solution $y_k = 0$. Thus the other initial condition $y_0 = 2$ is verified by the solution $y_k = 2(1/2)^k$.  Any help on how to get to the equation $y_k= (1/2)^k y_0$ will be appreciated. What do you call a response which does not address the question? When some one is asked a question, sometimes if they are trying to avoid answering the question, they respond with something unrelated. What is the word for that response?  Eg. A: Why were you late?     B: This bagel tastes good.  What I am looking for is the name of that response, not the action. How to revert a do-release-upgrade? I can update my Ubuntu to the new LTS version. As you can think, its not a highly important server since I run 13.10 (not a LTS version). Anyway - I actually want to upgrade my server, but would like to be able to revert this upgrade.   I would be able to reinstall Ubuntu 13.10 and overwrite it with my backup. But I want to know if there is a more comfortable way to do this. TBH I guess theres no command as undo-release-upgrade but I thought it would be worth to ask for it.  This is my current daily backup script  tar cvpzf $backup_file --exclude=/proc --exclude=/lost+found --exclude=$backup_file --exclude=/mnt --exclude=/sys --exclude=/media --exclude=/tmp / This is more of a panic question after reading reviews on Istanbul Atatürk Airport. They said it's messy and hard to navigate, therefore I'm asking questions here in name of my girlfriend who will need to transit through this airport.  My girlfriend (Canadian national) traveling from Toronto (YYZ) to Istanbul (IST) for a couple hours (~4 hrs, so transiting) in order to come to Pristina (PRN). I would like a quick guideline on how to pass through this airport seamlessly without facing any trouble or delay.  Her tickets are both with Turkish Airlines. She purchased it via a third party (Flighthub.ca). It's only one booking and it includes both flights in it.   Once my girlfriend departs, she's obviously required to follow the signs and go to the transit area. Once she's there, will she be required to present a ticket? Where does she get that ticket? Does she get it in YYZ or does she need to visit a counter in IST and get it? After she's got the proper ticket, what does she need to do exactly? Wait in line to have her passport checked? Will they also control her carryon?  After this step, does she simply go to the PRN flight gate and that's it?   We're simply worried about Istanbul Atatürk Airport because of the recent things that happened in Turkey (coup attempt and ISIS attack) and she doesn't wanna somehow end up locked up there. I've read that the airport is a mess lately and a lot of people will be there waiting in line. So, another question: Are 4 hours enough?  I would appreciate a step by step guideline on how she needs to navigate and what she needs to do in that airport to have a smooth experience without facing any delays. Also some misc information on Istanbul Atatürk Airport would be appreciated. How can I take browser screenshots at a higher resolution than my browser supports? Cite_key instead of a number, what is going on? I have the following problem: I correctly obtain a numbered bibliography at the end but along the text the cite_key appear instead of a number. How to fix this problem?   \documentclass[11pt]{book}  \usepackage[]{biblatex} \begin{document} %some text  ... \cite{ABKM2015}... %some text  \begin{thebibliography}{99} \bibitem{ABKM2015} Arroja, F. and Bartolo, N. and Karmakar P. and Matarrese, S. (2015). \newblock The Two Faces of Mimetic Horndeski Gravity             \newblock {\em ArXiV}, 1506.08575 (2015). \end{thebibliography} \end{document}   After compiling I get ... [ABKM2015] ... while I want for example  [1]. The identification of an electron as a particle and the positron as an antiparticle is a matter of convention. We see lots of electrons around us so they become the normal particle and the rare and unusual positrons become the .  My question is, when you have made the choice of the electron and positron as particle and anti-particle does this automatically identify every other particle (every other fermion?) as normal or anti?  For example the proton is a particle, or rather the quarks inside are. By considering the interactions of an electron with a quark inside a proton can we find something, e.g. a conserved quantity, that naturally identifies that quark as a particle rather than an antiparticle? Or do we also just have to extend our convention so say that a proton is a particle rather than an antiparticle? To complete the family I guess the same question would apply to the neutrinos. Continuing example in Beamer I'm looking to view and archive all my old DMs in Twitter, since I would like to revive conversations that took place 1 year ago.  Acording to Twitter they don't delete old messages, they simply archive them in their database.  Is there a way to view and download all of these messages, just like you can view all your old public tweets with third party apps?  UPDATE: I found  but apparently it's not working for DMs now Is the gradient a surface normal vector or does it point in the direction of maximum increase of f I'm having some trouble trying to visualize and physically understand what's happening with the gradient.  I understand that the following is true:   The gradient of f (grad(f)) points in the direction of maximum increase of f   However, later on, we are told that a gradient of a surface f (grad(f)) gives us the surface normal vector (i.e pointing away). How can that be? From the first statement, I thought that the gradient must be pointing in the direction of maximum increase of f - surely the direction of maximum increase of f should be a vector pointing in some direction on f itself. How can it be pointing outward as a surface normal vector? On  we try really hard to fix spelling, grammar, and capitalization mistakes in question titles in order to avoid the . But occasionally someone enters a question with an all-lowercase title ().  It would be useful if the system could nudge the user toward capitalizing titles property by showing a hint when the user appears to be capitalizing incorrectly. For instance:    As  and  note in comments, the feature should also try to detect and advise against Title Case and ALL CAPS. US tourism/business visa from non-resident country I applied for multiple visas before (not US visa), but all of them were from my residence country. In all of these cases, I can get official paper which support my evidence (bank statement, letter which states I am employed with high salary, marriage certificate, security clearance, ...).  It is the same question as , but I am not residing; I have a business visa.  case-specific details: I am from Egypt, I have business visa for Ireland. While in Ireland, I want to apply for US business visa.  Why not to apply from Egypt? Because the waiting time is too long (75 days). The waiting time in Ireland in only 18 days. Both visits (Ireland, US) are short visits (3 weeks for each). "Dummy Output" No sound in Ubuntu 16.04 None of the HDMI output are working, all saying "dummy output", it was working yesterday, but when I use the headphones it became soundless, with or without the headphones.  Thank you already! DMed for the first time yesterday and one of the things I feel I need to sort out, among other comments, improvements, and similar, is how combat itself is actually initiated. The main example I want to use involves  attempting to generate surprise conditions by players. Here the characters have entered a ruined city and generally been noisy about the whole thing - using a spell to make their voice louder and literally ask if there is anyone about. Any enemies around probably know what something is about to kick off but arguably don't know precisely what. After resting the PCs head up a long flight of steps to a temple on the edge of the city. At the top only one crests and finds 3 bandits lounging around, chatting, and doing whatever bandits do in their spare time. After a brief exchange of pleasantries a combat starts:  DM &quot;The bandit spits in your direction 'we're not done looting the temple, so you can clear off', and starts raising his crossbow as his mates emerge from their cover behind the pillars... PC &quot;I cast Firebolt at Bandit Keith&quot; DM &quot;Hang on, I hadn't finished, everyone rolls for initiative...  Which sparked a debate about whether or not the PC could preemptively cast/attack before the combat starts by &quot;instant actioning&quot; (as above) as I was describing the start of the combat. As far as the bandits are concerned a lone half-elf who is pretty heavily armed has popped up in front of them, not even tried to be diplomatic, and ended up saying something rather suggestive about their mothers. The PC then asked about it being &quot;surprise&quot; because the bandits wouldn't necessarily expect an attack, but my view of &quot;surprise&quot; is closer to an ambush where one party is unaware of the other's existence. (This precise example is close to how  works, however this specific PC was always the first of the party to go into rooms (only one with darkvision) and consistently felt they should get free rounds at the start of combat based on declaring attacks before I could &quot;start&quot; the combat.) The second example the party came to more bandits, who were not alert immediately, in an underground room. They used magic to yell something obscene at the bandits and shut off all the torches so the bandits were effectively blinded. At this point they wanted to burst into the room casting spells, swinging maces, and playing some &quot;meaty chords&quot; (the bard's words, not mine). Again they wanted surprise arguing that, despite the fact that the bandits were yelling and cursing in confusion, they couldn't be sure they were actually being attacked as such. In the end a character with darkvision wanted to sneak in to a corner and again wanted surprise based on passing stealth rolls, so they would start the &quot;combat&quot; by firing a crossbow. At that point I think I relented because it was clear that they would do anything to try and win combats in a single round. In a nutshell, my question is: &quot;how liberally can the concept of surprise be applied to combat - is it only when one party is literally unaware of a threat (as I read the rules), or just when they are caught slightly off guard by the exact situation?&quot; NB I already plan to address the attempts at interrupting descriptions with actions next session, because it happened at other times and actually threw me off quite a bit. How to stop Tkinter Frame from shrinking to fit its contents? This is the code that's giving me trouble.   f = Frame(root, width=1000, bg="blue") f.pack(fill=X, expand=True)  l = Label(f, text="hi", width=10, bg="red", fg="white") l.pack()   If I comment out the lines with the Label, the Frame displays with the right width.  However, adding the Label seems to shrink the Frame down to the Label's size.  Is there a way to prevent that from happening? How do you plot time on the X axis in excel? I need to plot the decay of my phone's battery against time over night. My starting time is 23:17:47 and my ending one is 07:05:49. I don't have any issue in changing the time format in the current one, selecting an XY chart and plotting time on the X axis.   The problem arises because Excel doesn't start the X axis at 23:17:47, but instead at 00:00:00, so my first value is drawn from the end of the graph and the goes back at the beginning when time values are over 00:00:00.   In other words, how do I set up the min time value to 23:17:47 and the max to 07:05:49 in excel? Show that if $p$ is prime then $\Bbb Z_p$ is a field Check my proof please.  Let $\Bbb Z_p:=\Bbb Z/p\Bbb Z$ be the quotient ring modulo $p$. I want to prove that if $p$ is prime then $\Bbb Z_p$ is a field.  Known facts about the quotient rings of the kind $\Bbb Z_n$ (I dont list all the characteristics of a ring, just some ones):   They are commutative rings with unity. $[0]=[n]$ is the identity of addition or zero. Then $[n]+[a]=[a]$ and $[n]\cdot[a]=[n]$ for all $[a]\in\Bbb Z_n$. $[1]$ is the multiplicative identity or unity. Then $[1]\cdot[a]=[a]$ for all $[a]\in\Bbb Z_n$. The addition is defined as $[a]+[b]=[a+b]$, and the multiplication is defined as $[a]\cdot[b]=[ab]$. $[a]=[b]$ means that exists $z\in\Bbb Z$ such that $a=b+nz$. $|\Bbb Z_p|=p$.   A ring $\Bbb Z_p$ dont have zero divisors, i.e. doesnt exist $[a],[b]\in\Bbb Z_p$ distinct of $[p]$ such that $[a]\cdot[b]=[p]$. Proof by contradiction: suppose that exists such $[a],[b]$ distinct of $[p]$ that are zero divisors. Then exist some $z_j\in\Bbb Z$ such that:  $$(a+pz_1)(b+pz_2)=pz_3\iff ab+pz_4=pz_3\iff ab=pz_5$$  but this is a contradiction with the assumption that $a,b\neq p$ and $p$ prime, so dont exist divisors of zero on any $\Bbb Z_p$.$\Box$  For any $[a]\in\Bbb Z_p$ distinct of $[p]$ exist $[b]$ such that $[a][b]=[1]$. Because $\Bbb Z_p$ dont have zero divisors and is finite for some $[a]\neq[p]$ we have that if $[b]\neq[c]$ then $[a][b]\neq[a][c]$. Proof by contradiction: if $[a][b]=[a][c]$ in the above conditions then  $$[a][c]=[ac]=[ab]=[a][b]\iff ac+pz_1=ab+pz_2\iff a(c-b)=pz_3$$  for some $z_j\in\Bbb Z$. But $pz_3\in[p]$, then $[a][c-b]=[p]$ but because there are no zero divisors in $\Bbb Z_p$ then or $[a]=[p]$ or $[c-b]=[p]$ what contradicts the above conditions.$\Box$  Because $[a][b]\neq[a][c]$ for $[a]\neq[p]$ and $[b]\neq[c]$ then for any $[a]\neq[p]$ we have that  $$[a]\cdot\Bbb Z_p=\Bbb Z_p\implies \exists [b]\in\Bbb Z_p:[a][b]=[1]$$  In other words: every element of $\Bbb Z_p$ but $[p]$ have a multiplicative inverse as stated above.$\Box$  Because $\Bbb Z_p$ is a commutative ring with $[1]\neq[0]$ and have multiplicative inverse for all their elements but $[p]=[0]$ then $\Bbb Z_p$ is a field.$\Box$ How to take the gradient of the quadratic form? It's stated that the gradient of:  $$\frac{1}{2}x^TAx - b^Tx +c$$  is   $$\frac{1}{2}A^Tx + \frac{1}{2}Ax - b$$  How do you grind out this equation? Or specifically, how do you get from $x^TAx$ to $A^Tx + Ax$? If I remove the heatsink from my processor temporarily, then later put it back without changing the heatsink or CPU, do I need to reapply thermal paste? What i did?   [root@mdfdevha1 ~]# Group_ID=`/opt/keycloak/bin/kcadm.sh get groups -r TEST`  [root@mdfdevha1 ~]# echo $Group_ID [ { "id" : "57c86153-11ba-4d19-aafb-9903ee00086b", "name" : "Admin_UserGroup", "path" : "/Admin_UserGroup", "subGroups" : [ ] } ] [root@mdfdevha1 ~]# SURE_USER_ID=`echo $Group_ID | cut -d : -f2 | awk -F\" '{print $2}'` [root@mdfdevha1 ~]# echo $SURE_USER_ID 57c86153-11ba-4d19-aafb-9903ee00086b   In this case i am able to get the id but my requirement little bit complex  I run below command   [root@mdfdevha1 ~]#  Group_ID=`/opt/keycloak/bin/kcadm.sh get groups -r My_Realm`   and then   [root@mdfdevha1 ~]# echo $Group_ID   Output was multiple record in JSON format  [ { "id" : "e27206c0-aeb6-43db-acda-c4ba43233071", "name" : "A1", "path" : "/A1", "subGroups" : [ ] },  { "id" : "89f3bd6a-33a9-4e02-9fe3-eae660c5a6cf", "name" : "Admin_UserGroup", "path" : "/Admin_UserGroup", "subGroups" : [ ] },  { "id" : "cdc2bce5-c3bb-4b88-bdaf-d87b8bb6c644", "name" : "Group104", "path" : "/Group104", "subGroups" : [ ] },  { "id" : "a0d749f2-ab6c-4c27-ad55-3357eaab9527", "name" : "Group105", "path" : "/Group105", "subGroups" : [ ] },  { "id" : "fbf99c34-d50d-408b-8d19-9713f9af3e3a", "name" : "Group106", "path" : "/Group106", "subGroups" : [ ] },  { "id" : "ebd8336f-4017-4fb1-8035-153ae1d9ba37", "name" : "Group201", "path" : "/Group201", "subGroups" : [ ] },  { "id" : "38f4aef7-caf0-4430-9e61-1ae7026e872f", "name" : "Group202", "path" : "/Group202", "subGroups" : [ ] },  { "id" : "436a0f4a-8b1b-4d7d-a014-fcec3513644e", "name" : "Group203", "path" : "/Group203", "subGroups" : [ ] },  { "id" : "41962c5f-e7e9-4748-b81f-e3f1880b78de", "name" : "Sure_Groups", "path" : "/Sure_Groups", "subGroups" : []}]   Now from the above output i want to get the ID where name = Admin_UserGroup.  How can this will achieve ?