How does this power supply make PWM?
How can I make schematic of this board?
What are the increased possibilities (if any) of being able to crack a private key given the following:   The associated bitcoin (ECDSA Secp256k1-based) public key is known. The private key has been used to generate a public key from a different ECDSA curve and that public key is also known. It is known that the two public keys are derived from the same private key. It is known which ECDSA curves were used to generate the public keys. It is known which ECDSA curve was used to generate which public key.   Does it make any more difference if there is data that is known to have been signed by the private key and the signature(s) are known and the raw data is known?  EDIT: I should have pointed out that the conditions are ANDed, I.e. All conditions are known. Sorry, I should have been clearer the first time. What's the difference between centre of mass & centre of gravity for massive bodies? My book says:     For most of the small objects, both are same. But for mammoth ones, they are really different ones. And in a gravity-less environment, COG is absent; COM still exists.   Ok, what's the big deal when things are small and big? How these two :  &amp; ? I've found that while using Vim on Windows Vim saves the file, a .ext.swp file that's deleted on closing the Vim window and a .ext~ file.   I assume the .ext.swp file is a session backup in case Vim crashes. What's the purpose of the .ext~ file however? Is this a permanent backup file? It's annoying as I'd like to copy all the files I'm working on to my host, without these duplicates. How can I turn this off or, if it's there for a good reason, hide the files? Well today as I was going home I got a strange email, in my private inbox (email associated with S.O.) asking me if I had solved a question on S.O. that I didn't ask. To be more precise I had given an answer.   After reading:       and several other email related issues on S.O. I decided to let you all know about this because probably I am not the only one.   So the mail subject was:     Re: Deleted facebook account - Cannot access my apps?   which refers to   And the body (masked last name of sender):      Hi Jimmy,      Just wondering if you ever got this question answered.  If not, maybe   a brief chat with a html wizpert could help: link   .      Good luck getting this resolved!      Cheers,      Michael      ------------------------- Michael W%^%^GF Founder, CEO @ Wizpert   Now I know that my email address is not visible and I read about the MD5 regarding gravatar but I don't think this is the case. I thought about some methods and sure it's possible via metadata, github, etc for someone to get my mail, but I do not dare to think that this has reached an automated level, so that some service could easily get the email of S.O. members.   I didn't get annoyed by the message, since the CEO took the time to contact me :-p but someone else could get annoyed by these kinds of messages, since they come in the important inbox of gmail.   What is more strange is that Wizpert seems to be a nice site and also is active in the Careers 2.0 if I am not mistaken.   Another thing that crossed my mind is that since Wizpert needs unanswered questions to promote their services, possibly this is an action of Wizpert trying to attract people into their services.   Well that's it, I hope I did good to let you know (maybe I did't include the correct tags). Forms Data Manipulation In Google Sheets I'm trying to develop a solution using Google Forms with Google Sheets that will collect Google Forms data and then automatically divide that one form submission's data into multiple rows of data in another sheet.   I've learned how to QUERY data (thanks to many of you on here) from one sheet to another, but I don't know how to automatically divide 1 row of data into multiple rows.  Here is a  in a visual manner (I will not delete it).   Basically, I have one Google form that collects the following.    Teacher Information (header data) Report Name (header data) Class Information (header data) Student#1 Data (record data: Multiple Form Fields) Student#2 Data (record data: Multiple Form Fields) Student#3 Data (record data: Multiple Form Fields) Student#4 Data (record data: Multiple Form Fields) Student#5 Data (record data: Multiple Form Fields)   I need an automated way to convert that single form response (1 row) into multiple rows (5 rows) each with the same 'header data' but with unique record date.   EXAMPLE Form Data  Header Data  -  Record Date (Student #1)  -  Record Date (Student #2)  -  Record Date (Student #3)  -  Record Date (Student #4)  -  Record Date (Student #5)   EXAMPLE Desired Manipulated Data      Header Data  -  Record Date (Student #1)     Header Data  -  Record Date (Student #2)     Header Data  -  Record Date (Student #3)     Header Data  -  Record Date (Student #4)     Header Data  -  Record Date (Student #5) Cruise ship in the Schengen area: Do the days spent at sea count toward the limit for short visits? I am planning on spending 90 days in Schengen zone countries.  I will be taking a cruise between Lisbon and Barcelona.  Do the days at sea count against the 90 days allowed for staying in the Schengen zone? FrameLabel and OverTilde How do I  prevent .xsession-errors from eating disk space? Why won't my computer go to sleep automatically? Windows 8 is set to sleep after 30 mins, and it used to work, but recently it's started refusing to sleep. (I can still manually ask it to go to sleep without any issue.)    I was having issues a while ago, but it was with my network adapter. That's since been disabled, so it's definitely not that:    I've checked to see what devices are able to wake up my machine, but it only appears to be my mouse:    Which is odd, because I haven't recently changed my mouse, and more confusing still: The monitor does go to sleep just fine. If it was actually the mouse keeping my system awake, I'm pretty sure the monitor wouldn't go to sleep.  I've checked my Wake Timers, and nothing:    I've also checked my existing requests...  UPDATE: I found something. What to do with it, I don't know...    Note: Even when /requests says that there's "NONE" under every category, my machine still won't sleep(!).    In short: How can I tell what's preventing my computer from Sleeping?    UPDATE: Ok, so I now have a few more pieces of the puzzle. I came back to my computer and it was ASLEEP! Lawks! It seems that the only times it doesn't sleep is if VLC Player is open, even if a video isn't actually playing.  UPDATE UPDATE: Ok, so it won't sleep sometimes when VLC Player ISN'T running, either. Bah! Remote desktop without a password I have an HTPC with a user that has no password and autologin.  I want to be able to connect to it via Remote Desktop without a password, so I can login with the original user. (I don't want to add another user just for the mstsc)  Is there a way of doing that?  The OS is Windows 7, 32bit. I am thinking about buying a new lens specifically to take photos of distant targets (birds, bears, etc). I currently own the Canon 70-300 IS USM, which is a nice lens, but I find that if I want to take a photo of anything further away than about 10 meters, the target does not fill a large amount of the frame (meaning I have to significantly crop in post production).  I am currently looking at the Canon prime 400mm, however I would like to determine at what distance an object will fill a reasonable proportion of the frame.  Is there a formula or rule of thumb I can apply that will help me in this situation? I realise the size of the target I am shooting will play a role here, so if we need to make an assumption about the size of the target please let me know. I have a list with 15 numbers in, and I need to write some code that produces all 32,768 combinations of those numbers.   I've found  (by Googling) that apparently does what I'm looking for, but I found the code fairly opaque and am wary of using it. Plus I have a feeling there must be a more elegant solution.  The only thing that occurs to me would be to just loop through the decimal integers 1–32768 and convert those to binary, and use the binary representation as a filter to pick out the appropriate numbers.   Does anyone know of a better way? Using map(), maybe? After restarting my computer when I am presented with the initial login screen (the light gray one with the restart and shut down buttons), I see only two of my three user accounts.  If I log in with one of these accounts, I can see, and log in to, the third (missing) account by either:   Logging off (Apple > Log Out...) to reach the second login screen (the dark gray one with sleep/restart/shut down buttons) Clicking on the fast user switching menu.   How can I restore this account in the initial (light gray) login screen?  I tried repairing disk permissions to no avail.  If I create a new account, it does show up in the list. Can a finite group act freely (as homeomorphisms) on $\mathbb R^n$ I am asking if whether or not a finite group acts freely (as homeomorphisms) on $\mathbb R^n$.  To answer in the negative, it suffices to show: for any homeomorphism $f$ such that $f^d=\text{id}_{\mathbb R^n}$, then $f$ has a fixed point.  I am looking for a complete self-contained answer. Write access without read access Problem:   Prove that a set of nine consecutive integers cannot be partitioned into two subsets with same product   My attempt:  This problem would be solved if it could be proven that 9 consecutive numbers cannot exist such that all the numbers are of the form $2^a  3^b  5^c  7^d$ where $a,b,c,d$ are integers.  A suitable hint would be appreciated, I don not want a complete solution.  Edit:  If there existed a prime factor greater than $7$ of any number present in the set, then its multiple cannot exist b/c $22-11&gt;9$  Edit 2: As mentioned by Erick, my reasoning is not valid for numbers $1-9$ and $2-9$, let this be an exception. Does proving (second countable) $\Rightarrow$ (Lindelöf) require the axiom of choice? I'm looking at buying a second-hand Mac, probably one that does not include an OS installation disk.  How can I scan it to make sure that it has not had security threats installed on it?  Is there a CD or DVD image I can boot it up with to perform this scan offline?  Edit: prospective machine would be a 2011- or 2012-vintage MacBook Pro.  Also note that I don't have reliable access to high-speed internet, so solutions that involve downloading 5GB over the Internet are not ideal.  For others, though,  may be helpful. How to implement keyboard shortcuts on websites How to make terminal transparent while still having its own background image? Is there a way to give terminal specific background image and make it 50% transparent at the same time?