Is there any website for announcements of journal's special issues?
Where can I find information about upcoming special issues in a field of study?
In a family with two children, what are the chances, if one of the children is a girl, that both children are girls?  I just dipped into a book, The Drunkard's Walk - How Randomness Rules Our Lives, by Leonard Mlodinow, Vintage Books, 2008. On p.107 Mlodinow says the chances are 1 in 3.   It seems obvious to me that the chances are 1 in 2. Am I correct? Is this not exactly analogous to having a bowl with an infinite number of marbles, half black and half red? Without looking I draw out a black marble. The probability of the second marble I draw being black is 1/2. How to remove comma between taxonomy terms? I style my taxonomy terms as boxes, so I don't need comma between them.  Could somebody give me any advice? Feedback Request: New Timeline Question View I am making a fudge recipe that calls for 1cup whole milk and 5 cups sugar. It also uses 2 sticks of butter and 25 marshmallows. I'm wondering if I can omit the milk and cut back on the sugar by using sweetened condensed milk. Prove if $\operatorname{ord}(a)=m$, $\operatorname{ord}(b)=n$, and $\operatorname{gcd}(m,n)=1$, then $\operatorname{ord}(ab)=mn$.   I was reading this and was thinking how this proof would look like. I tried to do it and am not sure if this is correct. Here is what I did:  If $a$ and $b$ commute then $(ab)^{mn} = a^{mn} * b^{mn} = (a^m)^n * (b^n)^m = 1 * 1 = 1.$ So $ord(ab) | mn$.  Now, take $k = \operatorname{ord}(ab) = m^\prime * n^\prime$ where m' is relatively prime with $n$ and $n'$ is relatively prime with $m$. By the result above $m' | m$ and $n' | n$. Now we have $((ab)^k)^{m/m'} = 1$ since $(ab)^k=1$. But on the other hand, by the commutativity:  $$((ab)^k)^(m/m') =$$  $$((ab)^(m' * n'))^(m/m') =$$  $$ a^{n'm} * b^{n'm} = $$  $$(a^m)^{n'} * b^{n'm'}=$$  $$b^{n'm'} = 1$$  This implies that $n' * m'$ is divisible by $n$. But $m'$ is relatively prime with $n$, so we must have $n' = n.$ By symmetry, $m' = m$. So $ord(ab) = mn$.  Just to say this again, I want to prove if $a$ and $b$ commute and $m$ and $n$ are relatively prime then   $$ord(ab)=mn.$$   The comments are vague. I guess this must be the answer then and there probably is not another way to do this. How do I pre-populate a jQuery Datepicker textbox with today's date? I have a very simple jQuery Datepicker calendar:  $(document).ready(function(){     $("#date_pretty").datepicker({      }); });   and of course in the HTML...  &lt;input type="text" size="10" value="" id="date_pretty"/&gt;   Today's date is nicely highlighted for the user when they bring up the calendar, but how do I get jQuery to pre-populate the textbox itself with today's date on page load, without the user doing anything?  99% of the time, the today's date default will be what they want. Why is free will a widely discussed, established concept? Does this concept emerge from religious / spiritual doctrine? Why is there so much interest in this topic?  If a neural-network based AI machine with a certain high degree of complexity scores a perfect 100 every run in a turing test, have we not already refuted the idea of free will? In fact, let me extend this reasoning, if ANY machine scores a single point in a turing test (and not 100), have we not already disproved (or alternatively put in great doubt the existence of) free will? If we already created a machine that can master a certain degree of human interaction, have we not then demonstrated that human interaction is programmable? (given enough time for the creation of a complex or more appropriately elaborative neural system).   From the perspective of an external observer, such a machine would be qualitatively human although intrinsically quantitative behind a stream of 1's and 0's. It would exhibit a type of decision making indistinguishable from that of a human. Does this not reduce the type of decision making we understand to be "free will" to something quantitative, deterministic, materialist? Friendly error page to replace WSOD This should be the easiest thing to do, but for some reason I just can't get it done.  I'm trying to get a friendly static error page to replace nasty 500 scenarios. For now I'm just trying to replicate a 500 situation on my local machine (Drupal 7 running on MAMP) by throwing in some crap characters on the top of my template.php in my theme, which does trigger a 500 situation, but for some reason the ErrorDocument directive in my .htaccess or Apache config file has no effect.  What I'm doing is quite simply this:  ErrorDocument 500 /500.html   And I have the simplest ever static html-page in the root of my site with the name of 500.html.  Still, when I intentionally break template.php, I get the dreaded White Screen Of Death instead of my nice friendly error page.  What am I doing wrong here? I've done this a billion times in non-Drupal setups but just can't get my head around this one. How can I chroot sftp-only SSH users into their homes? I want to give a client access to my server, but I want to limit those users to their home directories. I will bind-mount in any files I want them to be able to see.  I've created a user called bob and added him to a new group called sftponly. They have a home directory at /home/bob. I've changed their shell to /bin/false to stop SSH logins. Here is their /etc/passwd line:  bob:x:1001:1002::/home/bob:/bin/false   I've also changed the /etc/ssh/sshd_config to include the following:  Match Group sftponly         ChrootDirectory /home/%u         ForceCommand internal-sftp         AllowTcpForwarding no   When I try to log in as them, here's what I see   $ sftp bob@server bob@server's password:  Write failed: Broken pipe Couldn't read packet: Connection reset by peer   If I comment out the ChrootDirectory line I can SFTP in but then they have free rein over the server. I have found that ChrootDirectory /home works, but it still gives them access to any home directory. I have explicitly tried ChrootDirectory /home/bob but that doesn't work either.  What am I doing wrong? How can I limit bob to /home/bob/?  ----EDIT-----  Okay so I just had a look at /var/log/auth.log and saw this:  May  9 14:45:48 nj sshd[5074]: pam_unix(sshd:session): session opened for user bob by (uid=0) May  9 14:45:48 nj sshd[5091]: fatal: bad ownership or modes for chroot directory component "/home/bob/" May  9 14:45:48 nj sshd[5074]: pam_unix(sshd:session): session closed for user bob   I'm not entirely sure what's going on there,  but it suggests something is wrong with the user directory. Here is the ls -h /home output:  drwxr-xr-x 26 oli      oli      4096 2012-01-19 17:19 oli drwxr-xr-x  3 bob      bob      4096 2012-05-09 14:11 bob How do I get the size of a directory on the command line? Hyperref "enquotes" metadata Best way to select a subset of items in a long list Q&A blank in Stack Exchange Android app v1.0.95 - S10e/Android 10 Open source computer algebra systems for general relativity I would like to use an open source computer algebra system (CAS) for research in general relativity. Kindly suggest a good choice between Ipython and Sage. I am more interested in the theoretical aspect rather than numerical computations. Recommend a statistics fundamentals book To give you some background, I have a grasp on the basics of statistics and probability theory and even remember touching Bayes theorem at the university data mining course. But being a few years away from the university made my math got extremely rusty (so much for last-minute pre-exam cramming). While I remember various random basic concepts, there are a lot of gaps in my understanding of them.  What would be a good material (a book, a site, or otherwise equally accessible medium) to revise the fundamentals and go beyond basics? I'd like a book that can be actually read as a book (most statistics books are really dry and are close to being reference material, rather than a book). Teen fantasy book series about a world where people who showed creativity could learn magic, and were killed for it How would I convert a char array to int? Difference between $:=$ and $=$ I am sorry if this is quite elementary question. But I always think, that why we use $:=$ at some places, instead of $=$. Is there any fundamental difference between these two? Before reading Terry Tao's blog (4 months ago), I had never seen a symbol like this (:=). I have a table story_category in my database with corrupt entries. The next query returns the corrupt entries:  SELECT *  FROM  story_category  WHERE category_id NOT IN (     SELECT DISTINCT category.id      FROM category INNER JOIN         story_category ON category_id=category.id);   I tried to delete them executing:  DELETE FROM story_category  WHERE category_id NOT IN (     SELECT DISTINCT category.id      FROM category        INNER JOIN story_category ON category_id=category.id);   But I get the next error:      #1093 - You can't specify target table 'story_category' for update in FROM clause    How can I overcome this? Labeling (one-way) streets in QGIS?