jQuery UI Dialog in Tabs Using
jQuery ui tabs
How is the classical twin paradox resolved? I read a lot about the classical twin paradox recently. What confuses me is that some authors claim that it can be resolved within , others say that you need . Now, what is true (and why)? I would like to add texts with halo, in the composer (not in the map). Do you know a way to do it?  I'm using QGIS 2.0.1 How can I install apt packages non-interactively? If I run:  sudo apt-get --yes install postfix    or  sudo bash -c 'yes | apt-get --yes install postfix'   an interactive prompt appears to configure postfix. I need to automate the installation of postfix (I can modify the configuration files after the install).  Is there some magic that lets me install postfix (and other package) without human intervention? Accessing localhost (xampp) from another computer over LAN network - how to? I have just set up a wi-fi network at home. I have all my files on my desktop computer (192.168.1.56) and want to access localhost over there from another computer (192.168.1.2).  On my desktop I can access localhost through the normal . Apache is running on port 80 as usual.  Exactly what do I have to do to achieve this? There is documentation on the net but they either don't work or are too fragment and confusing to understand.  I think I have to make changes to my apache's httpd.conf file and the hosts file. Any ideas as to what changes to make? Bash is not finding a program even though it's on my path I see that Stack&nbsp;Overflow is very Linux specific. Doesn't Unix &amp; Linux and Ask&nbsp;Ubuntu cover much of the same ground? I see that Unix &amp; Linux and Server&nbsp;Fault also cater to many Linux server questions. Similarly, Ask&nbsp;Ubuntu and Super&nbsp;User seems to contain most like questions. When should a verb be followed by a gerund instead of an infinitive? Some verbs are followed by ing, e.g. I enjoy swimming. We can't say I enjoy to swim. Likewise, some verbs are followed by to, e.g. I decided to make a plan.   Which particular verbs are followed by ing and to? Can you please provide a list for that?  Moreover, which verbs can be followed by both without having the meaning changed? I am looking for an English translation of Markov's 1958 paper, On insolubility of the homeorphy problem, which I remember coming across on a website for a computational topology course (taught by Afra Zomorodian). Will it be possible to create apps/games in Java SE or Java ME on new Ubuntu phones? How to get only filename using sed How can I get only the filename using sed? I've this  out_file=$(echo $in_file|sed "s/\(.*\.\).*/\1mp4/g")   But I get the path too /root/video.mp4, and I want only video.mp4. Is it the "Stack Exchange Network" or the "Stack Overflow Network"? How do I show that there exists variational/action principle for a given classical system? We see variational principles coming into play in different places such as Classical Mechanics (Hamilton's principle which gives rise to the Euler-Lagrange equations), Optics (in the form of Fermat's principle) and even General Relativity (we get Einstein's equation from the Einstein-Hilbert action). However, how do we explain this very principle, i.e., more mathematically, I want to ask the following:      If I am given a set of generalized positions and velocities, say, $\{q_{i}, \dot{q}_{i}\}$, which describes a classical system with known dynamics (equations of motion), then, how do I rigorously show that there always exists an action functional $A$, where    $$A ~=~ \int L(q_{i}, \dot{q}_{i})dt,$$    such that $\delta A = 0$ gives the correct equations of motion and trajectory of the system?    I presume historically, the motivation came from Optics: i.e., light rays travel along a path where $S = \int_{A}^{B} n ds$ is minimized (or at least stationary). (Here, $ds$ is the differential element along the path). I don't mind some symplectic geometry talk if that is needed at all. How can I convert timestamps in a column to a date? I have a file containing this:  1415602803,LOGIN SUCCESS,AUTH,user2,192.168.203.63,10.146.124.73,59996,22 1415602807,LOGIN SUCCESS,AUTH,user1,172.24.31.10,172.32.1.1,48191,22 1415602811,LOGIN FAILED,AUTH,root,172.24.166.153,10.146.124.73,52506,22 1415602815,LOGIN FAILED,AUTH,user3,192.168.123.55,10.146.32.99,55750,22   I want to convert the timestamp to a date in this format:  2014-11-10 02:00:03,LOGIN SUCCESS,AUTH,user2,192.168.203.63,10.146.124.73,59996,22 2014-11-10 02:00:07,LOGIN SUCCESS,AUTH,user1,172.24.31.10,172.32.1.1,48191,22 2014-11-10 02:00:11,LOGIN FAILED,AUTH,root,172.24.166.153,10.146.124.73,52506,22 2014-11-10 02:00:15,LOGIN FAILED,AUTH,user3,192.168.123.55,10.146.32.99,55750,22   How can I do that?  I know this works: perl -pe 's/(\d+)/localtime($1)/e' (from ) but the output format is Mon Nov 10 02:00:03 2014.  I know this command can convert timestamps into my desired output: date -d@1415602803 +"%F %H:%M:%S", but I couldn't make it work with awk using system("cmd") because of all the quotations and whatnot. proving logical equivalence $(P \leftrightarrow Q) \equiv (P \wedge Q) \vee (\neg P \wedge \neg Q)$ I am currently working through Velleman's book How To Prove It and was asked to prove the following  $(P \leftrightarrow Q) \equiv (P \wedge Q) \vee (\neg P \wedge \neg Q)$  This is my work thus far  $(P \to Q) \wedge (Q \to P)$  $(\neg P \vee Q) \wedge (\neg Q \vee P)$ (since $(P \to Q) \equiv (\neg P \vee Q)$)  $\neg[\neg(\neg P \vee Q) \vee \neg (\neg Q \vee P)]$ (Demorgan's Law)  $\neg [(P \wedge \neg Q) \vee (Q \wedge \neg P)]$ (Demorgan's Law)  At this point I am little unsure how to proceed.   Here are a few things I've tried or considered thus far:  I thought that I could perhaps switch some of the terms in step 3 using the law of associativity however the $\neg$ on the outside of the two terms prevents me from doing so (constructing a truth table for $\neg (\neg P \vee Q) \vee (\neg Q \vee P)$ and $\neg (\neg P \vee \neg Q) \vee \neg (P \vee Q)$ for sanity purposes)  I can't seem to apply the law of distribution since the corresponding terms are negated.  Applying demorgans law to one of the terms individually on step 2 or 3 doesnt seem to get me very far either.  Did I perhaps skip something? Am I even on the right track? Any help is appreciated Engines that play Mangala? Wanted: question mark instead of bibtex key for missing citations (biblatex) Instead of having the citation key showing up in the document for missing references, I want to only have [?], as it is the case when using the default bibtex without biblatex. This behavior is driving me crazy, as it messes up all the formatting (especially in tables). I want to focus on writing and only later on deal with the erroneous citations.  This question is related to    and its MWE can be used. However, as pointed out beforehand, I want the question mark in the text instead of the citation key to not mess up the formatting (for missing citations). Add links to official status pages in the read-only mode status message When the site is in read-only mode, I get a message like this:     This site is currently in read-only mode.   Would it be possible to update that message to provide links to these resources on SE's status:   : Official SE tweets on SE's status. : Official blog posts on SE's status. Which one of these adjectives is correct? I can see that both of them are being used, I'm just not sure which one is grammatically correct. Are there any general rules to follow as to the use of one against the use of the other? In popular science books and articles, I keep running into the claim that the total energy of the Universe is zero, "because the positive energy of matter is cancelled out by the negative energy of the gravitational field".  But I can't find anything concrete to substantiate this claim. As a first check, I did a calculation to compute the gravitational potential energy of a sphere of uniform density of radius $R$ using Newton's Laws and threw in $E=mc^2$ for energy of the sphere, and it was by no means obvious that the answer is zero!  So, my questions:   What is the basis for the claim &ndash; does one require General Relativity, or can one get it from Newtonian gravity? What conditions do you require in the model, in order for this to work? Could someone please refer me to a good paper about this? round() doesn't seem to be rounding properly