Flying to US with German & Iranian Passport
Visiting USA as a German with Iranian parents
In MySql, find strings with a given prefix If $D$ is critical dimension of Bosonic strings, a particular derivation goes like the following, where we arrive finally at  $$ \frac{D-2}{2}\sum_{n=1}^\infty n + 1 = 0. $$ Now mathematically this is clearly a divergent series, but using zeta function regularization here we are taking  $$ \sum_{n=1}^\infty n = \zeta(-1) = -\frac{1}{12}. $$ And obtain $ D = 26 $ where $\zeta $ is the analytic continuation of the zeta function we know. But it makes no sense in putting $ s = -1 $ in the formulae $$ \zeta(s) = \sum_{n=1}^\infty \frac{1}{n^s}. $$ As the above is only valid for $ Re(s) &gt; 1 $. So what is going on in here? Can anyone give me a reasonable explanation about obtaining $ -1/12 $? I just found this identity but without any proof, could you just give me an hint how I could prove it? $$2^n = \sum\limits_{k=0}^n 2^{-k} \cdot \binom{n+k}{k}$$  I know that $$2^n = \sum\limits_{k=0}^n \binom{n}{k}$$ but that didn't help me I think it would be cool if a question would eventually open up to moderators to accept answers on the user's behalf, once a time period has passed. The asking user would get the rep score for the accept.  I know I've seen questions successfully answered with lots of upvotes and no accepted answer that sit there for months unaccepted. This would give superusers a little more functionality and would tie up a lot of loose ends.  What do you think? Taking a screenshot (within X) How can I take a screenshot in X.org?  I am unsure if the Print Screen button will "just work" and I don't know how I would go about testing it. Why are PATH variables different when running via sudo and su? On my fedora VM, when running with my user account I have /usr/local/bin in my path:  [justin@justin-fedora12 ~]$ env | grep PATH  PATH=/usr/kerberos/sbin:/usr/kerberos/bin:/usr/local/bin:/usr/bin:/bin:/usr/local/sbin:/usr/sbin:/sbin:/home/justin/bin   And likewise when running su:  [justin@justin-fedora12 ~]$ su - Password:  [root@justin-fedora12 justin]# env | grep PATH PATH=/usr/kerberos/sbin:/usr/kerberos/bin:/usr/local/bin:/usr/bin:/bin:/usr/local/sbin:/usr/sbin:/sbin:/home/justin/bin   However, when running via sudo, this directory is not in the path:  [root@justin-fedora12 justin]# exit [justin@justin-fedora12 ~]$ sudo bash [root@justin-fedora12 ~]# env | grep PATH PATH=/usr/kerberos/sbin:/usr/kerberos/bin:/sbin:/bin:/usr/sbin:/usr/bin   Why would the path be different when running via sudo? Numbering equations If I am writing a LaTeX document on TexMaker and I want to number my equation but most probably I will be adding details later on and I do not want to fall into retyping it all over again. So if for example I have an equation and currently called equation (1.2) that I want to refer later as in the following sentence "As you can see in (1.2)" but then I had to edit my document in a way that it becomes (1.3) now instead of (1.2) what should I do in order to avoid editing large number of equations and my reference to them? Safely turning a JSON string into an object How check with SOQL if a picklist value is available or not for a specified record type How check if a picklist value is available or not for a specified record type ( through SOQL)? Thanks in advance Batch files: How to read a file? I've lost my original power adapter, and I can't find the proper one in any of the stores currently available.  I've HP Compaq 6730b, and as per  it outputs 18.5V 3.5A. However, I've found an older power adapter I have which outputs 19.5V 4.62 A.  So, my question is: how much of a difference between those two it really is, and more importantly, how much of a risk would it be if I tried the power adapter I already have.  P.S. I know pretty much nothing about electricity/electronics. What is an adjective referring to “someone who puts people down”? I was just thinking about someone I went to school with who had a penchant for putting people down, and I was trying to think of a word that describes this, but couldn’t find it. It would be a synonym of caustic, abrasive, discouraging, and undermining, but these all have slightly different connotations (to wear away", cause discouragement or to make fall). I want an adjective that has the connotation of a hammer hitting you on the head. The word does not necessarily need to describe someone who does this on purpose, out of evil intent. Is there such a word?    The word should give you a mental picture of someone barraging you with negative comments, but it not necessarily affecting you. Think of someone who so often has something negative to “contribute” that many can just either ignore it or roll their eyes at it, and that is the extent of its effect. I keep getting the mental picture of the word buffet as in, how waves buffet the shore. A constant hitting, without the hitting necessarily being devastating in its destruction. Possible Duplicate:          On  it's a stated fact that if $I$ and $J$ are coprime ideals of a ring $A$, then $I^k$ and $J^\ell$ are also coprime for any integers $k,\ell$.   There's no proof given. Why is this fact true? Can I still use a usb flash drive after spilling water on it? So a few months ago I accidentally spilled a little water on a few of my usb flash drives. I really want to test and see if they work, but before I do, I just want to make sure that there's no risk of damaging my computer. I'm pretty sure it's fine, but I just got a new laptop and would hate to ruin it over something stupid. A word for a symbol which has outlived its origin I am quite sure that there is a word for a symbol which was originated by a real-life, physical prototype but has since then outlived its origin.  Most notable example: the save button with floppy drive on it. Also, to a lesser degree, envelopes in email clients, and so on.  The "anachronism" or "metonymy" are close, but not exactly what I'm searching for. What is the limit of cabin baggage on Wizz Air flights? What's the weight limit on Wizz Air, for cabin baggage?    I can't find anything about the weight on their website. I know that for Ryanair is 10kg, and EasyJet say they don't have a limit for weight. QGIS color polygon according to points I have two layers. Layer 1 contains points (x,y) and layer 2 contains one polygon. All points in layer 1 are positioned within the polygon of layer 2. The points in layer 1 contain an attribute with information on the topography/elevation at the specific point. Can I color the polygon in layer 2 based on attributes from the points in layer 1 in order to create an elevation map? Why is my StackExchange OpenID so hard to find? The security guard problem Looking for the actual reason of refraction explained precisely without analogies