Dependency issue while installing libgtk-3-dev on Ubuntu 18.04
Unable to correct problems, you have held broken packages
Testing stored procedure scalability I have an email application that will be called upon to deliver to the UI the number of new messages for a given user on each page load. I have a few variations of things I am testing on the DB level but all are abstracted by the stored proc call.  I'm trying to slam the DB to see what the breaking point (# of requests per second) would be.   In a nutshell, I have a table such as this userId, newMsgCount with a clustered index on userId. SQL should be able to server hundreds or thousands of these responses per second. I think the laggard is my .NET app.  How can I make this a good test to achieve the test results based on SQL performance?  Is there a tool for this that i can give it a stored proc name and param for it to pund my  DB?  I want to see if the DB can return a min. of 250 responses per second. How to match all words of one column against words in another column? Sum two dates in Java What diagnostic plots (and perhaps formal tests) do you find most informative for regressions where the outcome is a count variable?  I'm especially interested in Poisson and negative binomial models, as well as zero-inflated and hurdle counterparts of each. Most of the sources I've found simply plot the residuals vs. fitted values without discussion of what these plots "should" look like.  Wisdom and references greatly appreciated. The back story on why I'm asking this, if it's relevant, is .  Related discussions: Asphericity of pseudo circle Let $S$ be de pseudo circle (see for instance ).  How can I compute its higher homotopy groups?  The question came up while trying construct a weak homotopy equivalence $X\to Y$ that does not admit an inverse. Taking $X=S^1$, $Y=S$ and $f$ as in the wikipedia page should work, but I was not able to work out a "simple" way of calculating $\pi_n(S)$ for $n&gt;1$. By "simple" I mean that it should not invoke a generalization of that I am trying to prove. XeLaTeX update [20201004] and item ball in Beamer Beamer item balls go missing while compiling in XeLateX since yesterday's TeXlive update, however, the same code works with pdfLaTeX. Any solution, please. Here is my MWE: \documentclass{beamer}  \setbeamertemplate{itemize item}[ball] \setbeamertemplate{enumerate item}[ball]  \begin{document}  \begin{frame} \frametitle{A tested title} text \begin{enumerate}     \item this is an item \end{enumerate} text3 \begin{itemize}     \item this is an item \end{itemize} \end{frame} \end{document} Stopping resetting of linked locators in manipulate Which is easier, pushing or pulling? It is generally assumed, from a person's perspective, that pushing a cart is more easier than pulling one. But why? Is there any difference in terms of force required to achieve the same amount of displacement?  Or is it merely human perception?  Why is it that almost all automobiles transfer torque to the back axle. But then, why do trains have engines in the front? Indian Trains Wait List - will I get a seat? After the  of registering an account to book train tickets online using my British VISA card, I finally got into a position of being able to book a ticket, but what it appears to be telling me is that I'm only being added to a wait list, which I assume means my tickets aren't confirmed.  Can someone explain how the wait list works, and what my chances are of getting on the train successfully?    It currently says the wait list is 7 The train is the Mandor Express, from Delhi to Jodhpur on the 18th of Nov   Update: So I got the train! Although it didn't get confirmed until a few hours before it was due to leave. Gray iTunes album tracks I noticed that a few tracks from an album appear gray.    The tracks are downloaded, I can play them if I double click them explicitly, but they don't play as part of the album. If I click the album's "play" button, they're skipped (1 gets played, then 3, then 4, etc.)  Why is this happening and how can I prevent it?    I saw a similar question, , but that's not what I'm experiencing — for me, the songs do get downloaded and everything appears to be OK, they just get skipped when playing the album. Proof that a formula $\theta$ is valid if and only if $\forall x \theta$ is valid I need to prove for first-order logic that $\vDash\theta$ if and only if $\vDash\forall x \theta$. The proof for the forward direction seems simple enough:  Suppose $\theta$ is valid. Let $\mathfrak{A}$ be an arbitrary structure and let $s:V\to |\mathfrak{A}|$ be an arbitrary function assigning values of the universe of $\mathfrak{A}$ to variables. Then we know by assumption that $\vDash_\mathfrak{A}\theta[s]$.  But since $s$ is arbitrary, it follows that $\vDash_\mathfrak{A}\theta[s(x|c)]$, for all $c\in|\mathfrak{A}$. But this means that $\vDash_\mathfrak{A}\forall x\theta[s]$. Since $\mathfrak{A}$ and the function assigning elements of the structure to variables are arbitrary, it follows that $\vDash\forall x\theta$.   Now we have to show that if $\vDash\forall x\theta$, then $\vDash\theta$, and this is where I'm stuck. I understand why it makes sense that this should be true, I'm just having a hard time writing it rigorously. Any suggestions would be greatly appreciated. Leave bash script running on remote terminal while not logged in? I have a bash script that takes several hours to run.  While it's running, I would like to do other things, which may involve logging out or disconnecting from the internet (my script runs network tests on various computers).  I understand that there is a command that would allow me to run my tests from a remote terminal and logout of the terminal while it runs.  Does anyone know what this command is? why do chaperones bring protein into mitochondria? why would mitochondria need protein? Sounds trivial? Please help to sort out. I saw this picture while looking at dehydration reactions and cell revision.     And proceeded to the       Protein Folding and Processing in the ER: Various changes occur to proteins in the ER.   Chaperones and Folding: Polypeptides must assume the correct folding pattern in order to function properly. The correct folding of a protein is mediated by chaperones (they also are proteins--chaperones are abundant in the ER lumen). A completed polypeptide will assume the correct folding pattern spontaneously, however before translation is complete, it could assume an incorrect formation or it could aggregate with other partially made polypeptides. To prevent this, chaperones in the ER (and cytosol) bind to the nascent polypeptide and keep it from interacting with anything until the polypeptide is completely synthesized. (Chaperones bind to polypeptides destined for mitochondria then release them as they pass through the mitochondrial membranes. Chaperones on the inside of mitochondria bind until these polypeptides have completely entered.)   With regards to protein synthesis and folding, this kind of info is not in my textbook. Not in couple of the online open textbooks either. I even search for where do protein fold? to find out if there was a relationship. It doesn't say protein fold in mitochondria and turns out it's a question most scientist are looking for answers.  For whatever protein synthesis I have learnt so far, there was no mentioning of protein strands going into mitochondria but mitochondria as a power houses. What's going on here?   Why would a protein go into a mitochondria? How does it exit and where to? Solving the diophantine equation $y^{2}=x^{3}-2$ It is known that the diophantine equation $y^{2}=x^{3}-2$ has only one positive integer solution $(x,y)=(3,5)$. The proof of it can be read from the book "About Indeterminate Equation" (in Chinese, by Ke Zhao and Sun Qi). But the method I have known of solving this problem is algebraic number theory.  My question:      Does there exists an elementary method for solving the diophantine equation $y^{2}=x^{3}-2$?   I have gotten an elementary method by the assumption that "$x$" is a prime. That is, we can get a conclusion from the equation that $3\mid x$. Since $x$ is a prime we get the only solution $(x,y)=(3,5)$. But if $x$ is not a prime, the answer seems to be difficult.  Thank you for your help. Error 404 : While using flag Recently on Stack Overflow I got privilege to flag a post. So when I try to flag a post as duplicate. The diaglog box is not properly loading.         However I am easily able to use other flag option like "other","spam" or "offensive".   "other"        "spam"        "offensive"        I am using Google Chrome Version 28.0.1500.71 and Win XP Operating System. I have tried in firefox as well but it is showing me same problem. How to make a Snap application (ksnip) appear in "open with other application" context menu? For editing screengrabs, I prefer to use , since  was no longer installable without hassles on Ubuntu 18.04 and 20.04 However ksnip is available as a Snap App on my 20.04 ○ → snap list | grep ksnip ksnip                    1.8.0                       265    latest/stable    dporobic                 Unfortunately I have to start ksnip from the command line, then use the File-Open Dialog to pick a screengrab/PNG, then edit it in ksnip. This is should be easier. What I want is to use Nautilus File manager, then select the &quot;Open with other Application&quot; context menu item to select ksnip, and the have ksnip open the file I picked with nautilus. Nautilus Context Menu, selecting a PNG:  &quot;Select Application&quot; Dialog:  How can I achieve this? There is a &quot;View all Applications&quot; Button, but after clicking, ksnip does NOT appear in this list of apps. &quot;Find new applications&quot; does not work either. Maybe this is a duplicate, but I think we did not have the combination yet (Hack the dialog and Snap App)  (Note to self: maybe Shutter is usable again. Development had stalled for a while, or it needed a lot of deprecated versions of gnome libs as dependencies) . Is there a safe way to determine how powerful an opponent is? Subgroups of finitely generated groups are not necessarily finitely generated I was wondering this today, and my algebra professor didn't know the answer.      Are subgroups of finitely generated groups also finitely generated?    I suppose it is necessarily true for finitely generated abelian groups, but is it true in general?  And if not, is there a simple example of a finitely generated group with a non-finitely generated subgroup?  NOTE:  This question has been merged with another question, asked by an undergraduate.  For an example not involving free groups, please see Andreas Caranti's answer, which was the accepted answer on the merged question. Persistent do not disturb toggle in Yosemite possible? Does the new finding on "reversing a quantum jump mid-flight" rule out any interpretations of QM? new finding by Minev et al. seems to suggest that transitions between atomic states are not instantaneous, but continuous processes wherein a superposition smoothly adjusts from favoring one state to another (if I understand it correctly). The authors also claim to be able to catch a system "mid-jump" and reverse it. Popular articles are  and .  I am curious if this finding rules out any interpretations of QM. It seems to generally go against the Copenhagen attitude, which describes measurements as collapsing physical systems into a definite classical state. The popular articles indeed claim that the founders of QM would have been surprised by the new finding.  The link with the asterisk mentions that something called "quantum trajectories theory" predicts what was observed. Is this an interpretation, or a theory? And are they implying that other interpretations/theories don't work?