Lost connection to MySQL server at 'reading initial communication packet
Lost connection to MySQL server at 'reading initial communication packet', system error: 0
Do graduate schools care more about my grades in math courses or my general GPA? I'm currently a junior in mathematics at UIUC. I have been doing pretty well in my math courses (mostly A and A+). I will be completing a graduate course in topology, a second course in abstract algebra, and a complex analysis course before I graduate.  I feel that I can work hard to maintain good grades in my math courses, but my non-math courses are not that good (some B and C's).    Do graduate schools care more about my math courses grades more or my general GPA more?  Will poorer marks in non-math courses hurt my chances of getting into good grad schools? How to change file extension at runtime in Java How to close aberrant tooltips in Windows So, here I am, trying to watch The Cleveland Show (TM).      And, as happens from time to time, some program or another has left a modal tooltip.  I don't know which program; how can I lose the tooltip, short of logoff/reboot?  Currently happening on Windows 10, but I have seen it on other versions. How do we know what type of gauge field to add to a theory? I've been watching  and in one lecture, he discusses a very simple gauge theory.  We have a complex scalar field $\phi(x)$ with Lagrangian  $$\mathscr{L} = \partial_\mu \phi^* \partial^\mu \phi - V(\phi^* \phi)$$  and we want to do the gauge transformation $\phi(x) \to e^{i\theta(x)} \phi(x)$.  But the derivative term in the Lagrangian is not invariant if $\theta$ varies from place to place, so we add a new vector field $A_\mu$, and define it to transform like $$A_\mu \to A_\mu + \partial_\mu \theta$$ under the gauge transformation.  Then we change the Lagrangian to use covariant derivatives $D_\mu = \partial_\mu + iA_\mu$ instead of ordinary ones; now when the gauge transform is done all the derivatives of $\theta$ cancel out, and the result is invariant.  My question is: was there any freedom in choosing to add a vector field, with that specific gauge transformation law?  Are there any other ways we could get gauge invariance here—by using a different transformation law, or with a different type of field (say, a scalar, tensor, or spinor) with some other transformation law?  More generally, how can we tell what type of field is needed and what its gauge transformation law should be, to get some particular Lagrangian to be invariant under some particular gauge transformation? Which are safe and unsafe regions in Iran? Now there's a lot of propaganda in the west that leads us to believe Iran is dangerous and travellers shouldn't go there.  Obviously there are major political disagreements between several governments and the Iranian government and this should be taken into account.  But at a human level I have met many Iranians travelling elsewhere in the world and have found them to be friendly, charming, and hospitable. I have also met several western travellers who spent time in Iran, including hitchhiking around the country, who only have wonderful things to say about the country and its people.  As a traveller I've learned to trust the most what I hear from other travellers about a destination, especially ones which prefer similar ways of travel to myself. I've also learned to trust the opinions of inhabitants of countries bordering on the destination country the least.  Yet some people still insist that Iran is not safe for a traveller, or that .  I can look up for myself the general travel advisories issued by governments and disclaimers in WikiVoyage. So please don't regurgitate those an answers.  I want to know from travellers who've been there, from Iranians, or from references to specific incidents targeting foreigners/westers about which parts of Iran are no problem, and which parts should be avoided, even by experienced intrepid travellers.  (I realize any advice won't apply to Israeli citizens unfortunately. I'm Australian.) Why is part of my model not being rendered? Measure the size of a PostgreSQL table row I have a PostgreSQL table. select * is very slow whereas select id is nice and quick. I think it may be that the size of the row is very large and it's taking a while to transport, or it may be some other factor. I need all of the fields (or nearly all of them), so selecting just a subset isn't a quick fix. Selecting the fields that I want is still slow. Here's my table schema minus the names: integer                  | not null default nextval('core_page_id_seq'::regclass) character varying(255)   | not null character varying(64)    | not null text                     | default '{}'::text character varying(255)   |  integer                  | not null default 0 text                     | default '{}'::text text                     |  timestamp with time zone |  integer                  |  timestamp with time zone |  integer                  |   The size of the text field may be any size. But still, no more than a few kilobytes in the worst case. Questions  Is there anything about this that screams 'crazy inefficient'? Is there a way to measure page size at the Postgres command-line to help me debug this? I have a Sony VAIO S series with Windows 8 preinstalled, and I installed Ubuntu 12.10 on a new partition. When the PC boots Grub is display, and I can choose between Windows 8 (didn't worked at the beginning, had to change Grub settings) and Ubuntu 12.10. When I select Ubuntu 12.10 everything is OK, but when I use Windows 8, and I restart Grub isn't displayed anymore (Windows 8 boots immediately).  I booted a Ubuntu 12.10 LiveUSB, used efibootmgr, and found out that Windows 8 (each time it boots) changes EFI default bootloader from Grub to Windows Boot Manager.  How do I change this in Windows 8? I read something about bcdedit, but it does not work or I don't know how to use it... Does voltage drop occur with zero load and zero resistance Difference between $\mathbb C$ and $\mathbb R^2$ What are the basic differences between $\mathbb C$ and $\mathbb R^2$?  The points in these two sets are written as ordered pairs, I mean the structure looks similar to me. So what is the reason to denote these two sets differently? Convert .jar to .deb package What kind of capacitor could build up, and maintain a charge acquired from lightning? With constant travel, is it possible to not have a tax residence? Proof of inequality using AM-GM inequality prove that $x^2 + y^2 + z^2 \ge xy + xz + yz$  I tried proving it the way I prove $x^2 + y^2 \ge 2xy$. But it just doesn't seem to work. I tried using AM-GM. Should I be using GM-HM or AM-HM? I really don't know what the problem is and I'd appreciate any help and a full proof explanation. Thanks. Increasing notebook magnification pushes output onto a new line Does encrypting my home folder make my computer more secure? Do I have to enter my password more if my home folder is encrypted? What else should I know about encrypting my home folder? Is three hours enough for an international-domestic transfer at Delhi? My International flight will be reaching New Delhi IGI at 2:45 AM and I am planning to book a domestic flight at 5:45 AM.  Is three hours sufficient for me to move from International to Domestic?  I believe there must be a shuttle service inside the airport to transfer me from International to Domestic but still I don't know if Customs time at IGI could cause any delay or not. Distinguishing whether "up" is a preposition or a part of a phrasal verb in this case In the sentences below, “bill” and “hill” are both nouns.    He ran up a big hill. He ran up a big bill.   Can someone explain how one distinguishes whether “up” is a preposition or a part of a phrasal verb? Allow Documentation in other Stack Exchange communities I'm a Salesforce developer and would love Documentation to be available in other Stack Exchange communities. The reason is  a lot of Salesforce developers get help, especially newer ones like myself. The developer forums and documentation on  is mediocre. It would be nice to allow users to create their own and give pack on What is the single most influential book every designer should read? What is the single most influential book every designer should read?