I have heard in a talk given at the Fermilab (on Youtube) that we typically detect a neutrino burst from a core-collapse supernova CC SNR explosion 2 hours before we detect its electromagnetic radiation. When the question was raised about whether this violates the principle that nothing can travel faster than light, the answer given by the speaker was that when the collapse is happening, the neutrinos are expelled, whereas light from the supernova comes AFTER the explosion, not during the collapse. But doesn't it take about 1 second for the iron core to collapse completely? Why is there a 2 hours difference between our receiving the neutrino burst and light from the explosion?  Thank you  P.S. I read around and found that the reason is because light has to travel a lot of distance within the star which "slows" it down, however, as mentioned earlier, it takes only 1 second for the entire iron core to collapse, right?
A while back I read about the super Kamiokande detector detected a large neutrino flux and then several hours later a supernova was seen. Anyone know of this with sources? I don't recall the source at the moment.
What do the subscripts in expectations mean in loss function Can someone explain me what this equation means? I read it from page 152 on . Creating the Nabla operator (also known as Del operator) as an operator I have a valid B1/B2 visa valid to US till March 2019 on Indian passport, I changed my citizenship to Australian. Is my B1/B2 visa on Indian passport valid? How useful is that rule and how many times we can use that in one game?  Under what conditions can the en passant rule be used?  How often does it come up and is it a good idea to use it? Remotely uninstall apps? I have tried through the Google Play store and it does not seem possible from there, but does anyone know if it is possible to remove an application remotely?   In other words, if I do not have direct access to my phone, can I make use of some website, app or service to uninstall an app without being able to interact with the phone directly. Since it seems to me, that a lot of people still need sidebar workarounds, I would be interested to learn about the use-cases, experienced challenges and (most important) possible strategies to avoid them by using different approaches. This is related to the methods discussed here:   In my experience there are a few extremely important and constantly repeating patterns, which to my knowledge are still very hard to be solved using more official techniques. I will also contribute my own top-N use-cases, which are mostly related to UX and UI concerns. You are very welcome to add your own scenarios as answers and add comments on how you would avoid a workaround. My dream would be to team-elaborate strong and repeatable solution-patterns for the most common use-cases.  Finally I would be interested in the experiences of all of you who participate in the Aura pilot, which hopefully could make this kind of workarounds obsolete. Calculate last day of month If you provide 0 as the dayValue in Date.setFullYear you get the last day of the previous month:  d = new Date(); d.setFullYear(2008, 11, 0); //  Sun Nov 30 2008   There is reference to this behaviour at . Is this a reliable cross-browser feature or should I look at alternative methods? Possible Beamer bug: Frame number has different color than date in infolines footer I use TeX Live on Mac and I get my weekly updates through the TeX Live Utility. I am working on some slides for an upcoming talk. I am using the same Beamer templates and settings that I always use, so I was surprised to see that the page numbers that I always include at the bottom of my slides suddenly appeared in a different color. Here's an MWE:  \documentclass{beamer} \useoutertheme{infolines} \usecolortheme{beaver} \title{Title} \date{\today} %\setbeamercolor{page number in head/foot}{fg=darkred!60!black} \begin{document} \begin{frame} \end{frame} \end{document}     As you can see in the bottom right corner of the slide the page number appears but its color looks off. Until recently it would look exactly the same color as the date appearing next to it.  By Googling around a bit I managed to figure out how to get this to look normal again using the line commented out in the code above:  \setbeamercolor{page number in head/foot}{fg=darkred!60!black}   By uncommenting this line I got back the desired behavior:    So my question is not so much about how to fix this problem, but about why this is happening in the first place. Is this a bug that was introduced in a recent update, and if so will it be fixed? Is this a deliberate choice on the part of the developers (if so I can't imagine why)? Or am I doing something wrong or is something broken in my TeX setup?  I'd appreciate any insight on this. Thanks in advance! Exact sequence of sheaves with non exact sequence of global sections Let $X$ be some topological space. By $\mathcal{F}_i$ we denote some sheaves of abelian groups on $X$. The sequence of sheaves and morphisms  $$\mathcal{F}_1\longrightarrow \mathcal{F}_2\longrightarrow \mathcal{F}_3\longrightarrow... $$ is said to be exact if for each $x\in X$ the corresponding sequence of stalks $$(\mathcal{F}_1)_x\longrightarrow (\mathcal{F}_2)_x\longrightarrow (\mathcal{F}_3)_x\longrightarrow... $$ is exact. However if the sequence of sheaves is exact than the sequence of global sections is not necessarily exact! (The most famous example is the sequence of sheaves $$0\longrightarrow\mathbb{Z}\hookrightarrow \mathcal{O}\stackrel{\exp}{\longrightarrow} \mathcal{O}^*\longrightarrow0$$ considered as sheaves on $\mathbb{C}-\{0\}$, where $\mathcal{O}$ is a sheaf of holomorphic functions, $\mathcal{O}^*$ is a sheaf of holomorphic functions with no zeros).  So, could you give me some easy examples of such phenomenon ? In the bash terminal I can hit Control+Z to suspend any running process... then I can type fg to resume the process.  Is it possible to suspend a process if I only have it's PID? And if so, what command should I use?  I'm looking for something like:  suspend-process $PID_OF_PROCESS   and then to resume it with  resume-process $PID_OF_PROCESS Warning: Total photoshop newb!  I recently got a cool image of my fiancee and I holding hands and showing off her engagment ring. The backdrop is the beach:    I tried to trace an image using a combo of the laso and magic wand tools to select my target. Then I used that to pull out the target as another layer.  I then pasted in a background gradient.     Ended up with a really lame photoshoped looking picture. Notice the white lines where I didn't get the arms close enough and the choppy spots where I got too close.    So what's my main problem here?   Is their a way to bet a better cutout? Is their a blending tool that will make the background look more natural? both   I tried a dozen or so tutorials I found in google searches but they just don't blend these types of images together in any of them. Thanks in advance. Recovering eigenvectors from SVD DEF file syntax error in visual studio 2012 In my test class i have the creation of a dummy custom setting and a dummy lead:  Group g1 = new Group(Name='group name', type='Queue');              insert g1;             QueuesObject q1 = new QueueSObject(QueueID = g1.id, SobjectType = 'Lead');              insert q1;       SetOwner__c mycs = SetOwner__c.getValues('standardset');               if(mycs == null) {                               mycs = new SetOwner__c(Name= 'CustomValues');                  mycs.OwnerId__c ='00520000000z3PrAAI';                  mycs.RecordtypeID__c='012L00000004QsrIAE';                  insert mycs;      Lead lead = createNewLead(u2.id);                           insert lead;   ERROR:  MIXED_DML_OPERATION, DML operation on setup object is not permitted after you have updated a non-setup object (or vice versa): SetOwner__c, original object: QueueSobject: []   I get this error because i am trying to perform DML on setup and non-setup objects in the same transaction.  Any solution for this problem? Optimal way to ignore duplicate inserts? Background  This problem relates to ignoring duplicate inserts using PostgreSQL 9.2 or greater. The reason I ask is because of this code:    -- Ignores duplicates.   INSERT INTO     db_table (tbl_column_1, tbl_column_2)   VALUES (     SELECT       unnseted_column,       param_association     FROM       unnest( param_array_ids ) AS unnested_column   );   The code is unencumbered by checks for existing values. (In this particular situation, the user does not care about errors from inserting duplicates -- the insertion should "just work".) Adding code in this situation to explicitly test for duplicates imparts complications.  Problem  In PostgreSQL, I have found a few ways to ignore duplicate inserts.  Ignore Duplicates #1  Create a transaction that catches unique constraint violations, taking no action:    BEGIN     INSERT INTO db_table (tbl_column) VALUES (v_tbl_column);   EXCEPTION WHEN unique_violation THEN     -- Ignore duplicate inserts.   END;   Ignore Duplicates #2  Create a rule to ignore duplicates on a given table:  CREATE OR REPLACE RULE db_table_ignore_duplicate_inserts AS     ON INSERT TO db_table    WHERE (EXISTS ( SELECT 1            FROM db_table           WHERE db_table.tbl_column = NEW.tbl_column)) DO INSTEAD NOTHING;   Questions  My questions are mostly academic:   What method is most efficient? What method is most maintainable, and why? What is the standard way to ignore insert duplication errors with PostgreSQL? Is there a technically more efficient way to ignore duplicate inserts; if so, what is it?   Thank you! Is there an ideal PWM frequency for DC brush motors? Django: AppRegistryNotReady() Friend can't join world How to run a complete GUI as root? Difference between "while" and "whilst" Possible Duplicate:          In terms of construction of sentences, can the two words while and whilst be used interchangeably?