How to organize research notes?
Good practices for organizing notes
I forgot the passcode for my iPad restrictions. How can I disable them? Make your own .sty files Sorry to start a subjective question, but want to understand "own.sty" file.  Other than all \usepackage{} what sort of other commands can be added to the makeyourown.sty file.  Can you include \let command, and \newcommands in it.   What sort of precaution / structure newbies should follow. What is the meaning of this "let there be light" joke? how to create a roster sheet in sharepoint 2010 Raised index of partial derivative Is there exist a function defined on the real or complex numbers that, restricted to the integers, is equal to the factorial? GeoServer cutting off symbols close to tile edges? What is a deterministic method for evaluating a sensible buffer pool size? I'm trying to come up with a sane way to understand if the max server memory (mb) setting is appropriate (either should be lower, or higher, or stay the way it is).  I am aware that max server memory (mb) should always be low enough to leave room for the operating system itself, etc.    The environment I'm looking at has several hundred servers; I need a reliable formula I can use to determine if the present size of the buffer pool is appropriate since RAM is costed per GB allocated to each server.  The entire environment is virtualized, and "physical" RAM allocated to a VM can easily be changed up or down.  I have a particular SQL Server Instance I'm looking at now with a PLE of 1,100,052 seconds, which equates to 12.7 days (the amount of time the server has been up).  The server has a max server memory setting of 2560MB (2.5GB), of which only 1380MB (1.3GB) is actually committed.    I've read several items including one by Jonathan Keheyias () and another by Paul Randal (), and several others.  Jonathan advocates monitoring for a PLE below 300 per 4GB of buffer pool as being too low.  For the SQL Server Instance above, 300 * (2.5 / 4) = 187 results in a really really low target PLE below 300.  This instance has 290GB of SQL Server data (not including log files), and is only used for integration testing.  Assuming the last 12 days is representative of typical usage for this server, I'd say the max server memory (mb) setting could be lowered.  At the other end of the scale, I have another integration-test server with a PLE of 294, that has a max server memory (mb) setting of only 1GB.  This server has only 224MB of SQL Server data not including logs, and is running some BizFlow databases.  This server might benefit from a higher max server memory (mb) setting.  I'm thinking a good starting place for targets that might be assigned too much memory could include looking at:  SELECT      RamMB = physical_memory_in_bytes / 1048576     , BufferPoolCommittedMB = bpool_committed * 8192E0 / 1048576     , BufferPoolCommitTargetMB = bpool_commit_target * 8192E0 / 1048576     , PercentOfDesiredSizeMB = CONVERT(INT,(CONVERT(DECIMAL(18,2),bpool_committed)                              / bpool_commit_target) * 100) FROM sys.dm_os_sys_info;   If BufferPoolCommitTargetMB / BufferPoolCommittedMB is greater than 1, the server is not using the entire buffer pool.  If the machine in question also has a PLE of greater than "x" then it might be a good candidate for a decrease in max server memory (mb).  Since the Buffer Manager:Lazy writes/sec performance counter tracks the number of times SQLOS has written pages out to disk between checkpoints due to memory pressure, this might be another good thing to look at.  DECLARE @WaitTime DATETIME; SET @WaitTime = '00:00:15'; DECLARE @NumSeconds INT; SET @NumSeconds = DATEDIFF(SECOND, 0, @WaitTime); DECLARE @LazyWrites1 BIGINT; DECLARE @LazyWrites2 BIGINT;  SELECT @LazyWrites1 = cntr_value  FROM sys.dm_os_performance_counters dopc WHERE (         dopc.counter_name LIKE 'Lazy writes/sec%' COLLATE SQL_Latin1_General_CP1_CI_AS     )     AND dopc.object_name = 'MSSQL$' + CONVERT(VARCHAR(255),                SERVERPROPERTY('InstanceName')) + ':Buffer Manager';  WAITFOR DELAY @WaitTime;  SELECT @LazyWrites2 = cntr_value  FROM sys.dm_os_performance_counters dopc WHERE (         dopc.counter_name LIKE 'Lazy writes/sec%' COLLATE SQL_Latin1_General_CP1_CI_AS     )     AND dopc.object_name = 'MSSQL$' + CONVERT(VARCHAR(255),                SERVERPROPERTY('InstanceName')) + ':Buffer Manager';  SELECT LazyWritesPerSecond = (@LazyWrites2 - @LazyWrites1) / @NumSeconds;   The above code assumes the server is under load during the 15 seconds it takes to run, otherwise it will report 0; which might be a misleading false-negative.  Should I also look at PAGELATCHIO_* wait stats or some other wait type as an indicator of memory pressure, or lack thereof?   My question is, how can I reliably determine a "good" target value for PLE and max server memory (mb)? `tail -f` until text is seen I've got a CI server with a command-line interface that allows me to remotely kick-off a job (jenkins CI server and the jenkins-cli.jar tool).  After I kick the job off I tail -f the log (sorry for the messy command):  ssh -t my-jenkins-host.com "tail -f \"/var/lib/jenkins/jobs/$job_name/builds/\`ls -ltr /var/lib/jenkins/jobs/$job_name/builds/ | grep '^l' | tail -n 1|awk '{print \$9}'\`/log\""   After the job successfully completes, usually after at least 5 minutes, I get the following line on the output:  Finished: SUCCESS   Is there a good way to stop tailing the log at this point? i.e. is there like a tail_until 'some line' my-file.log command?  BONUS: extra credit if you can supply an answer that returns 0 when SUCCESS is matched, 1 when FAILURE is matched, and your solution works on mac! (which i believe is bsd based) Uneven line height in XeTeX I'm embarking on a journey to create a conference abstract book using XeTeX and got stuck within five minutes:        The missing 'g' in 'somethin' influences the line height of the following line. How can I correct this?  At the end I want to be able to include the abstracts and corresponding information through our online registration system, so this should be a global setting.  My MWE:  \documentclass[10pt, a5paper]{article} \usepackage{fontspec}  %% GEOMETRY \usepackage[left=2cm, right=1.5cm]{geometry} % to change the page dimensions  \newenvironment{AbsHead} {     \fontsize{16}{22}\headfont\noindent }% {     \vspace{0.5 cm} }  \newenvironment{AbsAuthors} {     \fontsize{12}{14}\authorfont\noindent }% {    \vspace{0.5 cm} }  \begin{document}  ￼￼￼￼\setmainfont{Minion Pro} \newfontfamily\authorfont{Helvetica Neue Light} \newfontfamily\headfont{Helvetica Neue Condensed Bold}  \begin{AbsHead}The XIAP  something something something somethin somethin somethin somethin somethin somethin somethin something something\end{AbsHead}   \begin{AbsAuthors}Somebody Someone\end{AbsAuthors}   \noindent Purpose: Lorem ipsum \end{document} Why are my quotation marks causing an “unexpected token” error with this command? I am going through Shankar's Principles of Quantum Mechanics and am having trouble finding the free particle propagator $U(t)$ that satisfies $$\lvert\psi (t)\rangle = U(t)\lvert\psi (0)\rangle$$ due to the degeneracy of the $E$ eigenkets. Shankar says that if the Hamiltonian has degenerate eigenvalues, we change the propagator equation from $$U(t) = \sum_{E} \lvert E\rangle\langle E\rvert e^{-iEt/{\hbar}}\tag{4.3.13}$$ to $$U(t) = \sum_{E} \sum_\alpha \lvert E, \alpha\rangle\langle E, \alpha\rvert e^{-iEt/\hbar} $$ where $\lvert E, \alpha \rangle $ are the orthonormal eigenkets for the $E$ eigenspace. This makes sense to me, because it seems like whenever we deal with degeneracy to use a projection. He also says for a Hamiltonian with no degeneracy to change the sum into an integral, so I imagine that for a Hamiltonian with a continuous, degenerate spectrum we would have this propagator: $$ U(t) = \sum_\alpha\int_\Re dE\lvert E, \alpha\rangle\langle E, \alpha\rvert e^{-iEt/\hbar}$$  I tried applying this to the free particle and had some trouble. In the book, after solving for the eigenkets and eigenvalues, $\lvert E\rangle = \lvert p\rangle$ and $p = \pm\sqrt{2mE}$, he chooses the propagator as a function of the momentum eigenvalues $p$ so that $$U(t) = \int_\Re dp\lvert p\rangle\langle p\rvert \exp(-ip^2t/2m).\tag{5.1.9}$$ I understand how he got to this, but I'm having some trouble because this doesn't appear to be the same expression that I have above. Splitting the integral up, we have $$U(t) = \int_{-\infty}^0dp\lvert p\rangle\langle p\rvert \exp(-ip^2t/2m) + \int_0^\infty dp\lvert p\rangle\langle p\rvert \exp(-ip^2t/2m)$$ The left integral can changed to an integral over $-p$, and the bounds switch from $0$ to $\infty$ such that: $$U(t) =  \int_{0}^\infty d(-p)\lvert -p\rangle\langle -p\rvert \exp(-ip^2t/2m) + \int_0^\infty dp\lvert p\rangle\langle p\rvert \exp(-ip^2t/2m)$$ Now we can substitute and interchange $\lvert p\rangle = \lvert E, + \rangle$,  $\lvert -p\rangle = \lvert E, - \rangle$, $E = p^2/2m$, and $dp = \pm mdE/\sqrt{2mE}$ to get: $$U(t) = \sum_{\alpha = \pm} \int_0^\infty dEm/\sqrt{2mE}\lvert E, \alpha\rangle\langle E, \alpha\rvert e^{-iEt/\hbar}. $$ This is the result that we are asked to prove in Exercise 5.1.1. Why is this not the same as the first expression for the propagator? Where did the extra $ m/\sqrt{2mE} $ come from? Am I just wrong in assuming that that is the general expression for a Hamiltonian with continuous and degenerate eigenvalues? Is there difference in force when the height increases? Consider a man with mass 50kg.   When he jumps from a 2 meter height, the total force is $F=ma$ ie (mass * gravity), but nothing happens to him. When he jumps from a 50 meter height, the total force is (mass * gravity ) same, but he dies.   Why is this happening? How to pick a specific symbol from a specific font? Why is no root pass needed to access MariaDB after upgrade to Ubuntu 16.04? In the book I'm study is written:     A normal subgroup of a group need not be characteristic.   And as an exercise I'm supposed to find an example, it also said that is pretty hard to find one. After trying for two days I wasn't able to find one example.   So, I'm asking for an example of a group $G$ with a normal subgroup $H$ that is not a characteristic of $G$.  I will add some context because maybe it will clarify why the book said it is difficult to find an example: the main problem with the exercise is that until it the book had only covered Group Definition, Subgroups, Lagrange's Theorem and Homomorphisms. So I'm supposed to find a example with such lack of advanced tools. I had to immediate shut down, and I lost about 20 unsaved tabs, is there any way to recover these? I would like to ask a question about Java that doesn't have a specific answer. It's a question to see what people think and to share their opinion.    Will Stack Overflow tolerate this, or is there another Stack Exchange resource where I may ask a question like this? TexShop will not compile without trashing aux files after every error I have a couple of LaTeX files with the same problem. If I produce an error, fix it, and then try to compile a pdf, I get the following error.  )Runaway argument? {{ ! File ended while scanning use of \@newl@ablel. &lt;inserted text&gt;                 \par l.90 \begin{document}   If I then click on the console or trash my .aux file, it compiles fine. Any thoughts on what is going on and how to prevent this annoying extra step? What is the expression on RegularExpressionValidator to check if the Textbox text is 6 or more characters long?