Command block shovel how to make it able to destroy course dirt I was trying to make a wooden shovel to break course dirt and I already have enter a command called /give @p 1 0 {CanDestroy:[“”]}, but the course dirt won't break when I want to do it.   It just says "missingno" when I scroll over the shovel. How to solve this?
How to get a tool that can only break specific blocks and has a name? So, right now I'm using this:  /give @p minecraft:diamond_pickaxe 1 0 {CanDestroy:[minecraft:stone]}   But I need one that also has the Name value. Anyone know this one?
Best lens for taking pictures of surfers I'm just trying to decide which new lens to get. I need to take surf and windsurf photos from onshore. Sometimes 300 mm is enough but there are many times they are too far away. I have a sigma 70-300 but I need something better, if the light is not perfect it doesn't give me the sharpness I hope for. I can not afford the 400L 2.8 of course, so I'm trying to choose between the Canon EF 100-400L, Canon EF 70-300L (which I heard is far better than the base one), or Sigma 50-500. My body is a canon 600D. Is there an SE for Cell-phones? Where would I ask a question pertaining to an ordinary phone? Or just cell phones in general? I saw Windows Phone while browsing the SE database, nothing else really popped out at me. Google didn't bring up anything either. Is that just too small a community to cover with SE? Is it safe to cancel CHKDSK when it has been started without any parameters? I know that it is not a good idea to forcibly stop a chkdsk process that has been executed with parameters like /f and /r.   But is it safe to stop the process when it has been started simply by the chkdskcommand? Chkdsk prints out a lot of errors and is continuing very slowly.  I suppose it to should be safe to cancel the process since there should be only in read mode, correct? Set Xorg to use only part of the screen How do I prevent widow/orphan lines? How to limit current of an AC signal For my project, I'm trying to work with the principle of electrovibration. This principle is about simulating textures using low current electricity on an insulated conductive surface ().  In order to do this, I will be experimenting with generated AC signals of 80 to 160 Vpp at 60Hz to 400Hz. I will do this by using an DC - AC converter, usually used for EL lamp applications.  My only concern is how to limit the current coming from the converter. Are the techniques for limiting AC current the same as DC, by using a simple resistor? Or is it, as I expect, more complex?  I need to limit the current to 0.5mA, for safety reasons. Simulate repeated rolls of a 7-sided die with a 6-sided die What is the most efficient way to simulate a 7-sided die with a 6-sided die? I've put some thought into it but I'm not sure I get somewhere specifically.  To create a 7-sided die we can use a rejection technique. 3-bits give uniform 1-8 and we need uniform 1-7 which means that we have to reject 1/8 i.e. 12.5% rejection probability.  To create $n * 7$-sided die rolls we need $\lceil log_2(  7^n ) \rceil$ bits. This means that our rejection probability is $p_r(n)=1-\frac{7^n}{2^{\lceil log_2(  7^n ) \rceil}}$.  It turns out that the rejection probability varies wildly but for $n=26$ we get $p_r(26) = 1 - \frac{7^{26}}{2^{\lceil log_2(7^{26}) \rceil}} = 1-\frac{7^{26}}{2^{73}} \approx 0.6\%$ rejection probability which is quite good. This means that we can generate with good odds 26 7-die rolls out of 73 bits.  Similarly, if we throw a fair die $n$ times we get number from $0...(6^n-1)$ which gives us $\lfloor log_2(6^{n}) \rfloor$ bits by rejecting everything which is above $2^{\lfloor log_2(6^{n}) \rfloor}$. Consequently the rejection probability is $p_r(n)=1-\frac{2^{\lfloor log_2(  6^{n} ) \rfloor}}{6^n}$.  Again this varies wildly but for $n = 53$, we get $p_r(53) = 1-\frac{2^{137}}{6^{53}} \approx 0.2\%$ which is excellent. As a result, we can roll the 6-face die 53 times and get ~137 bits.  This means that we get about $\frac{137}{53} * \frac{26}{73} = 0.9207$ 7-face die rolls out of 6-face die rolls which is close to the optimum $\frac{log 7}{log6} = 0.9208$.  Is there a way to get the optimum? Is there an way to find those $n$ numbers as above that minimize errors? Is there relevant theory I could have a look at?  P.S. Relevant python expressions:  min([ (i, round(1000*(1-(  7**i )  /  (2**ceil(log(7**i,2)))) )/10)  for i in xrange(1,100)], key=lambda x: x[1]) min([ (i, round(1000*(1- ((2**floor(log(6**i,2))) / (  6**i ))   )    )/10)  for i in xrange(1,100)], key=lambda x: x[1])   P.S.2 Thanks to @Erick Wong for helping me get the question right with his great comments.  Related question: Trying to remember the name of a grade-school book about an alien in a cereal box When I was a kid (Grade school, Elementary, can't remember the exact grade, but it was between 1992 and 1999) I read a book about a kid who found an alien in his cereal.  This alien informed him that he was there to defeat an evil threat to Earth, that took the form of the school's most popular student.  The alien came with a gun that did nothing, and the alien in the popular kid disguise had the power to make the kid's fingernails bleed by damaging his nerve endings.  In the end, it was revealed that the evil alien had a huge craving for, and vulnerability towards, pizza flakes, and was defeated by gorging himself on them and then exploding. What happens when a photon hits a mirror? When a photon of light hits a mirror does the exact same photon of light bounce back or is it absorbed then one with the same properties emitted? If the same one is bounced back does it's velocity take all values on $[-c,c]$ or does it just jump from $c$ to $-c$ when it hits the mirror?  Or, is the phenomenon of a mirror better explained using a wave analogy? If so, what is this explanation? Differences between ways to express future actions I asked this question  but I haven't gotten a useful answer. Could you tell me the difference in meaning between these sentences?        Do you think you will visit them next week?     Will you visit them next week?     Are you going to visit them next week?     Are you visiting them next week?     Are you going to be visiting them next week?     Are you planning to be visiting them next week?     Do you plan to visit them next week?      Will there be any difference in the answers?        I think I will visit them next week.     I will visit them next week.     I am going to visit them next week.     I am visiting them next week.     I am going to be visiting them next week.     I am planning to be visiting them next week.     I plan to visit them next week.      Can I use "planning to" instead of "going to"?  (E.g. "Are you planning to visit them next week? — Yes, I am planning to visit them next week.") Which of these sentences show that the subject of conversation has already been discussed? For example, I talked with a friend of mine about my plans to visit somebody. So my friend is aware of my plans.  And my last question. Which of these seven sentences express that the action will certainly take place? How to customize the ubuntu gnome 3 desktop? This is maybe a stupid question, but how can I choose my own background image on ubuntu gnome 3?? I click on Settings -> Background -> then I click on the current background preview to change it but I see only the defaults images! No + symbol to add or something. On the 'Pictures' tab there is nothing to select, I get an empty white page? I am running ubuntu gnome 13.04 3.9.6-030906-generic.  Thanks! Find all solutions to $x^2\equiv 1\pmod {91},\ 91 = 7\cdot 13$ I split this into $x^2\equiv 1\pmod {7}$ and $x^2\equiv 1\pmod {13}$.  For $x^2\equiv 1\pmod {7}$, i did: $$ (\pm1 )^2\equiv 1\pmod{7}$$ $$(\pm2 )^2\equiv 4\pmod{7}$$ $$(\pm3 )^2\equiv 2\pmod{7}$$ Which shows that the solutions to $x^2\equiv 1\pmod {7}$ are $\pm1$.  For $x^2\equiv 1\pmod {13}$, i did: $$ (\pm1 )^2\equiv 1\pmod{13}$$ $$(\pm2 )^2\equiv 4\pmod{13}$$ $$(\pm3 )^2\equiv 9\pmod{13}$$ $$ (\pm4 )^2\equiv 3\pmod{13}$$ $$(\pm5 )^2\equiv {-1}\pmod{13}$$ $$(\pm6 )^2\equiv 10\pmod{13}$$Which shows that the solutions to $x^2\equiv 1\pmod {13}$ are $\pm1$.  Thus, I concluded that the solutions to $x^2\equiv 1\pmod {91}$ must be $\pm1$. I thought that $\pm1$ were the only solutions, but apparently I am incorrect! How do I go about finding the other solutions to this congruence? How to get the current time in Python Software was blocked from opening because it is not from an identified developer I went to run LibreOffice on my OS X 10.9 and it would not let me install it. It said it was from an unidentified developer. I'm aware of the security features of the Mac and went to System Preferences to allow the software to run.   When I opened this setting I saw a button that said, '"LibreOffice" was blocked from opening because it is not from an identified developer.' and there was a button next to it that said "Open Anyway". I clicked this button and nothing happened. I clicked it multiple times, like a hundred, out of frustration. Is there something else I need to do? Could someone verify this is not a bug?   UPDATE: I've included the photo below of what my System Preferences screen looked like and the button I pushed that didn't work.  UPDATE II: So I tried opening the application again and went into the system preferences and pressed the "Open Anyway" button again and nothing happened at first but a few minutes later while I was typing an email something flashed across my screen, possibly another dialog (or more likely a chewpacabra), but it quickly disappeared and the next thing I know LibreOffice launched! How does a graduate program's admissions committee operate? How does a typical graduate program's admissions committee operate? (In the US --- I understand that in Europe admissions are often structured differently.)  My mental model at the moment is several professors sitting in a conference room with a stack of printed applications and a few piles: accept, maybe, and reject. Three or so professors will read an application and then make a decision. If the volume of applications is large enough, multiple meetings might be required. This is purely my imagination --- I don't know how accurate this model is.  Of course, I'm sure that how admissions are handled depends greatly on the school, program, and department. I'm interested in a few data points to get a rough idea of what the average is.  A few more specific related questions:   How much time does a typical committee spend on each application? I suspect there's a distribution. Obviously unqualified applicants will probably have their applications tossed into the reject pile pretty quickly. Qualified applicants' applications might receive more attention. Do admissions committees look online for more information about an applicant? I've read some professors (in CS --- not my field) will look at a student's research/project website, but I have no idea how common this is. Prove that $\lim_{x \to \infty}\big(\frac{x}{x-1}\big)^x$ is also $e$. Why is pruning not needed for random forest trees? Breiman says that the trees are grown with out pruning. Why? I mean to say that there must be a solid reason why the trees in random forest are not pruned. On the other hand it is considered very important to prune a single decision tree to avoid over fitting. Is there some literature available to read for this reason? Of course the trees may not be correlated but there still will be a possibility of over fitting. Rendering of Favorite/Ignored Tags in Firefox $(a,b) \mathbin\# (c,d)=(a+c,b+d)$ and $(a,b) \mathbin\&(c,d)=(ac-bd(r^2+s^2), ad+bc+2rbd)$. Multiplicative inverse? Let $r\in \mathbb{R}$ and let $0\neq s \in \mathbb{R}$. Define operations $\#$ and $\&amp;$ on $\mathbb{R}$ x $\mathbb{R}$ by $(a,b) \mathbin\#(c,d)=(a+c,b+d)$ and $(a,b) \mathbin\&amp;(c,d)=(ac-bd(r^2+s^2), ad+bc+2rbd)$ as addition and multiplication, respectively. Do these operations form a field?  I have shown that every axiom of the field is satisfied except for the "existence of multiplicative inverses" axiom. This is where I need help. We either need to show that this axiom fails and so we don't have a field or that the axiom $aa^{-1}=1$ is satisfied for every $a\neq 0 \in \mathbb{R}$  The multiplicative identity in this problem is $(1,0)$.  Any solutions or hints are greatly appreciated. Can I enter the UK with a Schengen visa?