I am a student applying to a graduate program. Part of the application requires submitting some letters of recommendation. I asked a former professor whose class I enjoyed, but she surprisingly asked that I write one myself, send it to her, and she would sign and submit it. This feels disingenuous at best and fraudulent at worst. Is this a common practice, or should I seek letters elsewhere?
At least two questions (, ) on this site indicate that in more than a few isolated cases at least, letters of recommendation are in fact written by the applicant and only signed off (or perhaps rephrased somewhat) by the recommender, who would actually be responsible for writing the letter.  Is there any evidence about the prevalence of this practice that goes beyond anecdotes? I realize that cross-country (cultural) difference may play a role.
Can one preserve food by periodically heating it? I get that keeping food temperature low will slow down chemical reactions and preserve food, but sometimes my sister preserves food by heating it every 6 hours or so (up to 1-2 days). Does this help preserving the food? If yes, how does it work?  If it matters, the food currently in question is , but I would appreciate a general explanation. In case anyone is wondering, she doesn't store it in the fridge because it is full. ContourPlot and Colorfunction Each time I changed and saved .config/user-dirs.dirs, and after restarted the system, the XDG_DOWNLOAD_DIR are reverted:  diff --git a/.config/user-dirs.dirs b/.config/user-dirs.dirs index 8f6e2db..dcff34e 100644 --- a/.config/user-dirs.dirs +++ b/.config/user-dirs.dirs @@ -7,11 +7,9 @@  #   XDG_PUBLICSHARE_DIR="$HOME/public"  XDG_TEMPLATES_DIR="$HOME/public/template" -  XDG_DESKTOP_DIR="$HOME/private/desktop"  XDG_DOCUMENTS_DIR="$HOME/private/doc"  XDG_PICTURES_DIR="$HOME/private/picture"  XDG_MUSIC_DIR="$HOME/private/music"  XDG_VIDEOS_DIR="$HOME/private/video" - -XDG_DOWNLOAD_DIR="$HOME/var/downloads" +XDG_DOWNLOAD_DIR="$HOME/"   How to make my changes permanent? Why does `last` show '{' and '|' in the TTY field? How can I add a program to the context menu of all files? How to resolve BackgroundContainer.dll error on startup? When I start my desktop it gives me an error about BackgroundContainer.dll.    How to get rid of it?  I found nothing when i started regedit.exe and searched (F3 or CTRL+F) for BackgroundContainer.dll Where does a spinning figure skater's energy go when she slows down? Post to facebook fan page as a user I know Blender is free software and bugs happen. But my question is, is it good practice to update Blender every time there is an update? Even if a minor one? (i.e I'd consider 2.56 to 2.56b minor or even 2.63, no?)  I haven't been updating very often for fear that updating frequently causes issues like broken settings, non-compatibility or lost user configs?  Or is updating often recommended to keep up to date and adapted to the new changes, i.e like upgrades in the GUI and functionality? Solving linear congruence (modular inverse or fraction) via gcd Bezout equation Isn't finding the inverse of $a$, that is, $a'$ in $aa'\equiv1\pmod{m}$ equivalent to solving the diophantine equation $aa'-mb=1$, where the unknowns are $a'$ and $b$? I have seem some answers on this site (where the extended Euclidean Algorithm is mentioned mainly) as well as looked up some books but there is no mention of this. Am I going wrong somewhere or is this a correct method of finding modular inverses? Also can't we find the Bézout's coefficients by solving the corresponding diophantine equation instead of using the extended Euclidean Algorithm? Replicate the Fourier transform time-frequency domains correspondence illustration using TikZ How to enable linking floating point library in TurboC? What is the best place for storing binary files that are related to data in your database? Should you:   Store in the database with a blob Store on the filesystem with a link in the database Store in the filesystem but rename to a hash of the contents and store the hash on the database Something I've not thought of   The advantages of (1) are (among others) that atomicity of transactions is preserved. The cost is that you might dramatically increase storage (and associated streaming/backup) requirements  The goal of (3) is to preserve atomicity to some degree - if you can enforce that the filesystem you are writing to does not allow files to be changed or deleted, and always has the correct hash as filename. The idea would be to write the file to the filesystem before permitting the insert/update referencing the hash - if this transaction fails after the filesystem write but before the database DML, that is fine because the filesystem is 'faking' being the repository of all possible files and hashes - it doesn't matter if there are some files in there that are not being pointed to (and you could clean them up periodically if you are careful)  EDIT:  It looks like some RDBMSs have this covered in their individual ways - I'd be interested to know how others do it - and particularly in a solution for postgres Integral of sinc function multiplied by Gaussian I am wondering whether the following integral $$\int_{-\infty}^{\infty}  \frac{\exp( - a x^2 ) \sin( bx )}{x} \,\mathrm{d}x$$ exists in closed form. I would like to use it for numerical calculation and find an efficient way to evaluate it. If analytical form does not exist, I really appreciate any alternative means for evaluating the integral. One method would be numerical quadrature including Gaussian quadrature, but it may be inefficient when the parameters $a$ and $b$ are very different in scale.  EDIT : In view of  discussion, we have decided to add OP's self-answer to the end of the question, for it does not qualify as an answer yet contains vital details. The copying is unabridged. Thanks very much for your comments, and the following result was obtained including the case for $x_0 \ne 0$: $$ \int_{-\infty}^{\infty} dx \exp[-a(x-x_0)^2] \frac{ \sin(bx) }{ x } = \pi \exp(-a x_0^2) \mathrm{Re}\left(\mathrm{erf}\left[\frac{b+2iax_0}{2\sqrt{a}}\right] - \mathrm{erf}\left[\frac{2iax_0}{2\sqrt{a}}\right]\right) $$ where $a\gt0, b, x_0$ are assumed to be all real. (note: coefficients etc may be still wrong...) This integral appears in a type of electronic structure calculation based on a grid representation (sinc-function basis). I believe the above result should be definitely useful. Thanks much!! --jaian I am going to Nepal and probably, same as everyone, through Delhi. I was considering going overland from Delhi to Kathmandu, however I have found many posts that advise against it in favor of a flight. The following concerns are the key to the proper decision, I think.  Does the overland route offer a good scenery and cultural experience or is it  better to spend that time in Nepal?  What is the rough cost of an overland journey and how does it compare with a flight?  In case of a flight, is the Indian visa necessary? Stopping Dwarf Fortress from auto-pausing Is it possible to prevent DF from pausing every time something comes up (liking hitting gold or whatever). The reason is that I am doing extensive mining and I want to leave the process unattended till it is over. Years ago I read short story about a man sitting in his room. Suddenly appears the same man but from the future and gives him an advice about the future. Original man seems to agree to follow that advice. Man from the future goes away. Then another version of that man from another future comes and gives a completely opposite advice and begs original man to follow it. Then this second version of this man from future also left. Original man stays alone not knowing which advice from future he must follow. Can we have a notification when the answer to any of my question got edited? If a user asked a question and got an answer which was not helpful.  After sometime the answerer edits the answer with some good content. How the OP will get to know that?  Is it necessary to add comment check my edited answer?  We can say that the OP should refresh the page to find the helpful answer.  Consider if the OP finds the answer as helpful and accepted that. After sometime if the answerer/anyother user edit the answer to change the content which may not solve the issue.   How will it be notified to OP?  currently we are notifying the OP when there is any comment to the queation or any new answers or any comments with the name of OP with @ to any answer.  This will lead the future visitors to confuse and reduce the quality of post.  Can we have a notification to the original poster when the answer to any of his/her question got edited? If a friend wants to transfer $7000 to me, what is the best way to do it, especially if we don't share the same banks? We could do wire transfer, but that comes with its own fees. Could we also do direct deposit? Paypal doesn't allow such large lump sum transfers.  This would be US-to-US transfer. Do I need a RHEL subscription to install packages?