Is it bad to start a sentence with a citation e.g.   [14,6] give 3 and 2.4-approximations for the FVS problem.   Also when do you not use numbers from one to ten as worded.   e.g.  The earliest algorithms had an approximation factor of 16, later algorithms improved the approximation factor to ten, 9.5, eight, 6.5 and three respectively.  The cited questions is about why my 2nd question is about the convention and whether or not it applies to a continuous quantity when it takes discrete values  e.g. does the rule apply to continuous variables e.g. The height of the ball is maximized at time 2e, four, 4.4,3, 2\pi, 2.5e, eight, 3e, 3 \pi and nine  and yes [14,6] are references listed in my bibliography I've found numbered bibliographies to be quite common but I'm not sure where it is okay to start the sentence with a citation.
Why do English writers avoid explicit numerals? The junction has a stop sign on each of the four entrances.   The junction has a stop sign on each of the 4 entrances.   The first is preferred, for some reason, by many English texts. Why? I haven't seen this phenomenon in other languages.
When to use "do" in phrases which are not questions? TTY doesn't wait for password Accept Multiple Answers or Split Bounty among Several Users Often more than one person contributes to the community coming up with the final accepted answer to a question. However, it is only possible to accept a single answer. Restricting to one final answer does make sense for the sake of referencing that answer later, but in many cases that answer is the product of the input from several individuals. I would like to be able to decide how much of a bounty goes to different users, or some other mechanism to recognize the contribution of multiple users. Of course I could always upvote their previous answers, but this is really incorrect if their previous answers aren't the complete, final answer I've accepted.  What think you metaSOrs? Meaning of "* */1 * * *" cron entry? Somehow, I am finding it difficult to understand tweaking around * parameters with cron.  I wanted a job to run every hour and I used the below setting:  * */1 * * *   But it does not seem to do the job. Could someone please explain the meaning of above and what is needed for the job? How to delete file(s) in secure manner? Is there a way to make sure that a deleted file can not be recovered?   As you know, deleting a file by pressing shift-del or using trash doesn't mean that file is gone forever. It resides somewhere in the computer.  In day to day life, law enforcement or thieves use recovery programs to reveal our private data or something else.   They can recover all data that resides on hard disk, in RAM, and even USB.  To protect us from these people, what should one do? Which program should one use?  Note: I don't want an answer like first use a recovery program then erase that file with shred. With just one program, I want to erase all unused/deleted files on my computer. Is there an image editor like Windows' Paint for OS X? I tried out several image editors mentioned on  but some of them (like  and ) were very disappointing. These apps were too simple and low level.  What do you suggest for a (preferably free) image editor on OS X?  P.S: I was using  on Linux and also know that it was released for OS X too, but I want to find new good applications. First Order Time-Variant System : Picard Method I looking at a time variant first order system. I am trying to prove that a sequence of functions $x^{[k]}(t)$ generated using Picard iterations converges uniformly on some interval $[0,T]$.  Given:  $\dot{x}(t)=A(t)x(t)$ where $x(0)=x_0$  $x(t)=x∈R^n$ where $A(t)$ is a $n×n$ matrix  Assume there exists $M$ such that $||A(t)||\le M$ for all $t\ge 0$ and that $A(t)$ is a piecewise continuous function. Show that, for any $T &gt; 0$, a solution exists in the interval $[0,T]$.  I know that $x(t)=x_0+\int^t_0A(τ)x(τ) dτ$ must be satisfied if the solution does indeed exist.  I am supposed to use Picard iterations to prove this, which I am not familiar with yet. But I know that they are of the form: $x^{[k+1]}=x_0+\int^t_0A(τ)x^{[k]}(τ) dτ$. Where $x^{[0]}(t)=x_0$  Can I use the standard Picard proof to prove this or do I need to start somewhere else?  I was also asked to show that this method satisfies  $|x^{[k+1]}(t)-x^{[k]}(t)|\le |x_0| $$\frac{π^{k+1}(t)}{(k+1)!}$ where $π(t)=\int^t_0||A(τ)||dτ$.  I have no idea where to start with this, but hopefully it will become clearer once I finish the first part. problems using apa6e with biblatex-apa As in  I'm trying to use apa6e and biblatex-apa together and having problems.  Before I arrived at these problems, over the course of many hours of much reading, I first managed to get BibTeX working as expected in a simple input file (by modifying sample2e.tex). Then I managed to get apa6e working as expected based on the author's example in apa6e.pdf (which uses apacite). But when I try to get apa6e working with biblatex-apa, I end up with problems.  Here's my input file:  \documentclass{apa6e}  \usepackage[american]{babel} \usepackage{csquotes}  % biblatex \usepackage[style=apa]{biblatex} \bibliography{biblatex-apa-test-references}  \title{An Example Document} \shorttitle{Psychology: the end} \author{Silly Name}  \authornote{\dots} \abstract{\dots}  \begin{document}  \maketitle  This is an example input\cite{7.01:2} file.  Comparing it with the output it generates can show you\cite{7.01:3a} how to produce a simple document of your own.  \printbibliography  \end{document}   Attempting to typeset this in TeXShop by running LaTeX, then BiBTeX (which based on console messages, does seem to correctly call biblatex rather than BiBTeX), then LaTeX again, I get the following error message which I am having great difficulty (no doubt due to my lack of experience with TeX and co.) decoding.  (./test6.aux) (/usr/local/texlive/2011/texmf-dist/tex/latex/psnfss/ot1ptm.fd) *geometry* driver: auto-detecting *geometry* detected driver: pdftex (./test6.bbl) Underfull \hbox (badness 10000) in paragraph at lines 18--18  []\OT1/ptm/m/n/12 An Ex-am-ple Doc-u-ment   Underfull \hbox (badness 10000) in paragraph at lines 18--18  []\OT1/ptm/m/n/12 Silly Name   Underfull \hbox (badness 10000) in paragraph at lines 18--18  []\OT1/ptm/m/n/12 Author Note  [1{/usr/local/texlive/2011/texmf-var/fonts/map/pdftex/updmap/pdftex.map}] Underfull \hbox (badness 10000) in paragraph at lines 18--18  []\OT1/ptm/m/n/12 Abstract  [2] Underfull \hbox (badness 10000) in paragraph at lines 18--18  []\OT1/ptm/m/n/12 An Ex-am-ple Doc-u-ment   Underfull \hbox (badness 10000) in paragraph at lines 25--25  []\OT1/ptm/b/n/12 References  ./test6.tex:25: Undefined control sequence. &lt;argument&gt; \mkbibdateapalongextra  (/usr/local/texlive/2011/texmf-dist/tex/latex/psnfss/ot1pcr.fd) (/usr/local/texlive/2011/texmf-dist/tex/latex/psnfss/ot1ztmcm.fd) (/usr/local/texlive/2011/texmf-dist/tex/latex/psnfss/omlztmcm.fd) (/usr/local/texlive/2011/texmf-dist/tex/latex/psnfss/omsztmcm.fd) (/usr/local/texlive/2011/texmf-dist/tex/latex/psnfss/omxztmcm.fd) Overfull \hbox (8.03372pt too wide) in paragraph at lines 25--25 [][]  \OT1/ptm/m/n/12 Gilbert, D. G., Mc-Cler-non, J. F., Ra-bi-novich, N. E.,  Sugai, C., Plath, L. C., As-gaard, G., ... Botros,  ./test6.tex:25: Undefined control sequence. &lt;argument&gt; \mkbibdateapalongextra                                    {year}{month}{day}\iffieldundef {endyear}{... l.25   I tried many different sources in several different *.bib files before eventually trying the .bib database shown above and included with biblatex-apa. All trials gave a similar error.  Can someone help? I'm impressed that the poster above was able to do anything with apa6e and biblatex-apa, and if I only had her problem of having the reference page title show up in bold, I'd be really happy.  If you need to know, my tools are from a fresh installation of MacTeX that I immediately updated using the TeX Live Utility. I've checked my versions for apa6e (v0.3) and biblatex-apa (v4.2), and I think these are current. Many To Many Relationships Just upgraded to Mountain Lion and I have to buy iPhoto again? He called her, emailed her, texted her, tweeted her—all to no use.   Strictly speaking, I would need to write texted her and tweeted her, but I'm omitting and to convey a rhythm and sense of urgency. What do you call this kind of construction, and is it accepted grammar (at least for creative writing, if not in an academic context)? I have run into an issue with WPF and Commands that are bound to a Button inside the DataTemplate of an ItemsControl. The scenario is quite straight forward. The ItemsControl is bound to a list of objects, and I want to be able to remove each object in the list by clicking a Button. The Button executes a Command, and the Command takes care of the deletion. The CommandParameter is bound to the Object I want to delete. That way I know what the user clicked. A user should only be able to delete their "own" objects - so I need to do some checks in the "CanExecute" call of the Command to verify that the user has the right permissions.  The problem is that the parameter passed to CanExecute is NULL the first time it's called - so I can't run the logic to enable/disable the command. However, if I make it allways enabled, and then click the button to execute the command, the CommandParameter is passed in correctly. So that means that the binding against the CommandParameter is working.  The XAML for the ItemsControl and the DataTemplate looks like this:  &lt;ItemsControl      x:Name="commentsList"     ItemsSource="{Binding Path=SharedDataItemPM.Comments}"     Width="Auto" Height="Auto"&gt;     &lt;ItemsControl.ItemTemplate&gt;         &lt;DataTemplate&gt;             &lt;StackPanel Orientation="Horizontal"&gt;                 &lt;Button                                                  Content="Delete"                     FontSize="10"                     Command="{Binding Path=DataContext.DeleteCommentCommand, ElementName=commentsList}"                      CommandParameter="{Binding}" /&gt;             &lt;/StackPanel&gt;                                 &lt;/DataTemplate&gt;     &lt;/ItemsControl.ItemTemplate&gt; &lt;/ItemsControl&gt;   So as you can see I have a list of Comments objects. I want the CommandParameter of the DeleteCommentCommand to be bound to the Command object.  So I guess my question is: have anyone experienced this problem before? CanExecute gets called on my Command, but the parameter is always NULL the first time - why is that?  Update: I was able to narrow the problem down a little. I added an empty Debug ValueConverter so that I could output a message when the CommandParameter is data bound. Turns out the problem is that the CanExecute method is executed before the CommandParameter is bound to the button. I have tried to set the CommandParameter before the Command (like suggested) - but it still doesn't work. Any tips on how to control it.  Update2: Is there any way to detect when the binding is "done", so that I can force re-evaluation of the command? Also - is it a problem that I have multiple Buttons (one for each item in the ItemsControl) that bind to the same instance of a Command-object?  Update3: I have uploaded a reproduction of the bug to my SkyDrive: ERROR: cuvid requested, but not all dependencies are satisfied: cuda/ffnvcodec I am trying to compile FFMPEG with Nvidia Cuda support, on Debian 9.3. Parameters, what I am using:  --enable-cuda --enable-cuvid --enable-nvenc --extra-cflags=-I/usr/local/cuda/include --extra-ldflags=-L/usr/local/cuda/lib64 --enable-gpl --enable-libx264 --disable-x86asm --enable-libx265 --enable-libfdk-aac --enable-nonfree   Nvidia Cuda with drivers are installed. When I try to configure ffmpeg, it says:  ERROR: cuvid requested, but not all dependencies are satisfied: cuda   Newer ffmpeg will show a similar, re-worded message:  ERROR: cuda requested, but not all dependencies are satisfied: ffnvcodec   I absolutely don't know why I'm having this issue, because I am compiling ffmpeg on all of our trans-coding servers. How do I change my timezone to UTC/GMT? Currently when I execute the date command from bash I get the following displayed  Thu May 17 12:21:00 IST 2012  Below is my timezone config based on executing dpkg-reconfigure tzdata     Current default time zone: 'Europe/Dublin'   Local time is now: Thu May 17 12:32:52 IST 2012.   Universal Time is now: Thu May 17 11:32:52 UTC 2012.     Any idea how I change from IST to UTC/GMT? What is the exact use of the symbols $\partial$, $\delta$ and $\mathrm{d}$ in derivatives in physics? How are they different and when are they used? It would be nice to get that settled once and for all.  $$\frac{\partial y}{\partial x}, \frac{\delta y}{\delta x}, \frac{\mathrm{d} y}{\mathrm{d} x}$$   For what I know, $\mathrm{d}$ is used as a small infinitisemal change (and I guess the straight-up letter $\mathrm{d}$ is usual notation instead of italic $d$, simply to tell the difference from a variable). Of course we also have the big delta $\Delta$ to describe a finite (non-negligible) difference. And I have some vague idea that $\partial$ is used for partial derivatives in case of e.g. three-dimensional variables. Same goes for $\delta$, which I would have sworn was the same as $\partial$ until reading this answer on Math.SE:    Then to make the confusion total I noticed an equation like $\delta Q=\mathrm{d}U+\delta W$ and read in a physics text book that:     The fact that the amount of heat [added between two states] is dependent on the path is indicated by the symbol $\delta$...   So it seems $\delta$ means something more? The text book continues and says that:     a function [like the change in internal energy] is called a state function and its change is indicated by the symbol $\mathrm{d}$...   Here I am unsure of exactly why a $\mathrm d$ refers to a state function.   So to sum it up: down to the bone of it, what is $\delta$, $\partial$ and $\mathrm{d}$ exactly, when we are talking derivatives in physics.  Addition  Especially when reading a mathematical process on a physical equation like this procedure:  $$\delta Q=\mathrm{d}U+p\mathrm{d}V \Rightarrow\\ Q=\Delta U+\int_1^2 p \mathrm{d}V$$  It appears that $\delta$ and $\mathrm{d}$ are the same thing. An integral operation handles it the same way apparently? I'd like to download automatically tons of papers listed on .bib file so I'm trying to find a way to facilitate the process by, e.g. I import or input to a tool a certain .bib file which contains a list of literature, the output is the literature's .pdf file. Any idea to do so? Can an observer B move in such a way that his clock will run faster than that of a fixed observer A? My understanding of Special and General Relativity comes from books which attempt to explain them to non-experts in these fields.   Let A and B be observers, which at some time t(0), are together at some location P fixed to the earth's surface. A and B are provided with "clocks", which at time t(0), are identical lumps of the same radioactive element-that has a very long half-life. A and A's "clock" remain fixed to the earth's surface. B and B's "clock" leave A and stay together, but eventually return to A after some interval of time T (as measured by A's "clock"). If, during this time T, B's velocity relative to A is sufficiently close to the velocity of light or B remains close to a sufficiently massive body, it seems that time can "pass more slowly" for B than for A. So that when B rejoins A, B's "clock" will contain more of the radioactive element than A's "clock"   My question is: Are there any scenarios that B together with B"s "clock" can undergo (during the time T) which will cause time to "pass more quickly" for B than for A? So that when B rejoins A, B's "clock" will contain less of the radioactive element than A's "clock". If there are no such scenarios, is there any fact or law in Relativity theory which rules them out? I am looking for various ways of explaining to my students (in an elementary statistics course) what is a two tailed test, and how its P value is calculated.  How do you explain to your students the two- vs one- tailed test? Modifying list while iterating Noether's Theorem: Lie groups vs. Lie algebras; finite vs. infinitesimal symmetries I've had a brief look through similar threads on this topic to see if my question has already been answered, but I didn't find quite what I was looking for, perhaps it is because I'm finding it hard to put words on my question and I hope that you will be able to help me ask it clearly.  I'm trying to link what I know from mathematics to what we are writing in physics for Noether's theorem. If I understand correctly we are looking at the symmetries of the action i.e. under which symmetry groups is it invariant. Noether's theorem allows us to calculate a conserved current in the case of a continuous symmetry (Lie groups), by means of so-called infinitesimal symmetries which I believe to be elements of the Lie algebra (so the tangent space to the neutral element) of the Lie group.  I'm guessing that if the action is invariant under the symmetry then it's "variation" should be 0 when we vary the system (space-time coordinate, or field) using this symmetry; it is exactly this step that I would like to understand better, how can I formalize this step correctly mathematically? How should I understand this variation, and how does it's calculation give rise to the elements of the Lie algebra?