When atom absorb energy, how does the nucleon know?
How does one account for the momentum of an absorbed photon?
How many times to roll a die before getting two consecutive sixes? Basically, on average, how many times do you have to roll a fair six-sided die before getting two consecutive sixes? I'm new to inequalities in mathematical induction and don't know how to proceed further. So far I was able to do this:  $V(1): 1≤1 \text{  true}$  $V(n): n!≤((n+1)/2)^n$  $V(n+1): (n+1)!≤((n+2)/2)^{(n+1)}$  and I've got : $(((n+1)/2)^n)\cdot(n+1)≤((n+2)/2)^{(n+1)}$ $((n+1)^n)n(n+1)≤((n+2)^n)((n/2)+1)$ I am trying to INSERT INTO a table using the input from another table. Although this is entirely feasible for many database engines, I always seem to struggle to remember the correct syntax for the SQL engine of the day (, , , , and ).  Is there a silver-bullet syntax coming from an SQL standard (for example, ) that would allow me to insert the values without worrying about the underlying database? Is empty set element of every set if it is subset of every set? This problem is from Discrete Mathematics and its Applications  My question is on 9b. I know that the sign represents an element is a member of. (from book)  I know that the O with a slash across it is the empty set which &quot;is a special set that has no elements&quot;. From , I got that the empty set is a subset of all sets, meaning that every member of the empty set(nothing) is also a member of any other set. Based on all of this, for 9b, would {0} contain the empty set because it fundamentally has the elements that consist of the empty set(nothing) or does it physically have to have the empty set? Get a list of dates between two dates Using standard mysql functions is there a way to write a query that will return a list of days between two dates.  eg given 2009-01-01 and 2009-01-13 it would return a one column table with the values:   2009-01-01   2009-01-02   2009-01-03  2009-01-04   2009-01-05  2009-01-06  2009-01-07  2009-01-08   2009-01-09  2009-01-10  2009-01-11  2009-01-12  2009-01-13   Edit: It appears I have not been clear. I want to GENERATE this list. I have values stored in the database (by datetime) but want them to be aggregated on a left outer join to a list of dates as above (I am expecting null from the right side of some of this join for some days and will handle this). Block quote with big quotation marks I have a program which spawns several child processes.  I want to know which files this program and its children are creating, deleting, and modifying.   inotifywait can tell me which files are being accessed, but cannot tell me which process is doing it. And I have to know where the files are being created in order to set up the monitor. auditctl will let me log which processes modify a file, but, again, I have to know where the files are in order to set up logging. lsof will tell me all of the files, but doesn't seem to be a good solution for real-time tracking.   Is there anything that will let me monitor a program's file manipulation without knowing a priori which files will be manipulated? For an existing set of line features, I would like to generate a perpendicular line, of say 1km, at the midpoint of each existing line feature in ArcGIS.  I imagine that The methodology would be to:   create a tangent line at the midpoint of each existing line feature calculate the angle of the tangent line based on the angle of the tangent line, calculate the location of the endpoint of the new line create the new line with the calculated endpoint of the new line and the existing midpoint of the old line   Let's assume that we are in a UTM projection and can use coordinates to calculate distance and direction.  How would I do this with ArcGIS tools or with ArcPy? Is there a rational number between any two irrationals? Suppose $i_1$ and $i_2$ are distinct irrational numbers with $i_1 &lt; i_2$.  Is it necessarily the case that there is a rational number $r$ in the interval $[i_1, i_2]$?  How would you construct such a rational number?  [I posted this only so that the useful answers at  could be merged here before that question was deleted.] Creating multiline strings in JavaScript I am using gedit text editor with embedded terminal in ubuntu 12.04. I'm trying to search for some text using grep. I want to search for this line of code   'type' =&gt; 'select'   I tried:  grep -r '\'type\' =&gt; \'select\''  But grep didn't return any results.  So can someone kindly tell me how to search for the code above? Do I need to activate the firewall? I only use Ubuntu for a home desktop use? I am a novice at Ubuntu (12.04).  I have it on my netbook which I use mainly for surfing the net, learning python and remote desktop into my work computer.    Do I need to enable a Firewall type software?  If so, what would you suggest, and what are sensible default suggestions? This morning I read this sentence (see ):     On July 24th and again on July 29th,   Egyptian police did shoot dead unarmed   African migrants attempting to cross   that border.   Why "did shoot" and not "shot"? I've posted a lot to StackOverflow, and I've noticed something kind of irritating with the formatting in writing questions and comments. If I need to put something inside a &lt; and a >, without spaces in the middle (like right there), it will think it's code and not show up, like this   (obviously it won't come up what I wrote there, or else this wouldn't be an issue, but if you open up the question to edit you can see what's written there.)  If I want it to show up, right now I have to add an extra set of brackets inside of the originals with a junk variable, like right &lt;here> (again, open in edit window to see).  This is really annoying when trying to show variables like lists that require those brackets, and I feel like the junk variables could confuse people looking at the edits. Is there a way to get around this formatting? Thanks! Encouraging people to explain downvotes Note: If you're looking for a simple explanation as to why comments aren't required on downvotes, see .   I used to get "upset" (though that is too strong a term) when I got downvoted without comment. If my answer isn't good enough then I'd like to know why. Not only does it improve the answer for the OP but it improves my knowledge too.  Where the down-vote has been explained I've found it useful &amp; it has improved my answer, or forced me to delete the answer if it was totally wrong.  So is there any way we can encourage people to leave a comment? Perhaps they don't lose rep if they explain their down-vote?  I must admit though that I haven't always explained my down-vote either so you could call me a hypocrite. I've also grown a thicker skin over the months of using SO (it seems to have come with the higher rep score ;-)), so I'm less bothered about this now. Where can I access OS X keyboard shortcuts, say for Dropbox sync? How do I change directory back to my original working directory with Python? Why too many capacitors in parallel for Vdd supply net? Can't we just add all to replace with one big capacitor? How to include graphics with spaces in their path? Is it possible to prevent DHCP service on SBS 2003 from shutting down due to rogue DHCP server?