How do electrons flow in AC?
pattern of moving electrons in wire under AC
If you copy the contents of   httpd.conf   and then paste it into a cat command.. such as this one..  #!/bin/bash cat &gt; /test &lt;&lt; EOF pasted here.. EOF   you run into this error:  -bash: command substitution: line 1: unexpected EOF while looking for matching `'' -bash: command substitution: line 4: syntax error: unexpected end of file   perhaps the solution is to escape the dollar signs and maybe even quotes and so on..  but given that this is such a large file.. can dollar signs be automatically be escaped ?  is my only option to escape them via another program and then give it to the cat command ? Formula to add minutes to date+time in Excel If I have a cell formatted as date+time in Excel, how can I add to this in terms of minutes? It would need to work whether I was adding 20 minutes, or 2,500 minutes.   So, for example if I had this spreadsheet, what formula could I put in B5 to get a result of 2013-09-22 09:10?    I tried using =B4+TIME(0,B3,0), but it gives 2013-09-21 09:10 which is a day off. It works fine though if B3 is less than a day's worth. How do I use sudo to redirect output to a location I don't have permission to write to? I've been given sudo access on one of our development RedHat linux boxes, and I seem to find myself quite often needing to redirect output to a location I don't normally have write access to.  The trouble is, this contrived example doesn't work:  sudo ls -hal /root/ &gt; /root/test.out   I just receive the response:  -bash: /root/test.out: Permission denied   How can I get this to work? Custom attributes - Yea or nay? What Canon lens would one use for Sartorialist-like street photography? You probably know Scott Schuman and his blog (). What kind of lens (that is not expensive) would you recommend for Canon 550D to achieve similar effect (in terms of DoF etc.)? I'm a newbie so I'm not sure how to properly interpret those photos' EXIF info. My guess is, that a similar effect can be achieved using .   PS:   Update: Thank you guys for all the answers, it's much more clear for me right now. I think I'll try the Canon 50mm f/1.4 lens. If $f$ is entire and $|f|\geq 1$, then show $f$ is constant. I know I'm going to use Liouville's Theorem, but my main question is why is $1/|f(z)|$ entire as well if $f$ is entire? Is this just a basic property: if $f$ is entire, then $1/f$ is entire? Thanks for the help. Converting PostGIS point to text causing loss of data? I have a road network and want to test connectivity between the features.  I am having trouble with two specific features, the rest of the dataset is functioning just fine.  When I get those 2 links' start &amp; end locations using ST_StartPoint and ST_EndPoint, the result is that they are slightly different.  However, when I convert the result to text by wrapping it like so:  ST_AsText(ST_StartPoint(geom)) and ST_AsText(ST_EndPoint(geom))  then the results are exactly the same.  Is it possible they are actually off by a tiny amount like .000000001 and the ST_AsText loses a decimal point? Integral $ \int_{-\infty}^{\infty}\frac{x^{2}}{\cosh\left(x\right)}\,{\rm d}x $ I need to compute the improper integral $$ \int_{-\infty}^{\infty}\frac{x^{2}}{\cosh\left(x\right)}\,{\rm d}x $$ using contour integration and possibly principal values.  Trying to approach this as I would normally approach evaluating an improper integral using contour integration doesn't work here, and doesn't really give me any clues as to how I should do it. This normal approach is namely evaluating the contour integral $$ \oint_{C}{\frac{z^2}{\cosh\left(z\right)}\mathrm{d}z} $$ using a semicircle in the upper-half plane centered at the origin, but the semicircular part of this contour integral does not vanish since $\cosh\left(z\right)$ has period $2\pi\mathrm{i}$ and there are infinitely-many poles of the integrand along the imaginary axis given by $-\pi\mathrm{i}/2 + 2n\pi\mathrm{i}$ and $\pi\mathrm{i}/2 + 2n\pi\mathrm{i}$ for $n \in \mathbb{Z}$. The residues of the integrand at these simple poles are $-\frac{1}{4}\mathrm{i}\pi^{2}\left(1 - 4n\right)^{2}$ and $\frac{1}{4}\mathrm{i}\left(4\pi n + \pi\right)^{2}$, so that even when we add up all of the poles, we have the sum $4\pi^{2}\mathrm{i}\sum_{n = 0}^{\infty}\,n$, which clearly diverges.  Any hints would be greatly appreciated. Partition 256 GB SSD for dual Boot, Windows 10 + Ubuntu 19.04 I plan on installing Ubuntu 19.04 and give it 100 GB of my 256 GB SSD space and leave the rest for Windows as I would primarily be using Ubuntu.     A. Now, as I plan to install a lot of applications in Ubuntu, should I give more space to the / partition than the home partition? (Or maybe even drop the /home altogether?).    B. I have another 128 GB SD card for files like photos, audio and video files. Please suggest me the optimal partitioning for the use case.    C. Also, I have 8 GB of RAM so what should be the optimal swap partition size?    D. How would the distribution be if I choose "install Ubuntu alongside Windows" option? Hyphens in words with prefixes like neo-Nazism I have a question regarding the use of hyphens in words with certain prefixes. For example,     Neo-Nazism   Neo-Confucianism   Neo-liberal     are words with a hyphen, but     Neoplatonism   Neocolonialism   are words without hyphens. I'm especially confused with neo-Confucianism and neoplatonism: one contains  a hyphen and a capital letter and the other doesn't.  Is there a specific rule for hyphens in words with prefixes or is it purely arbitrary? An example of a norm which can't be generated by an inner product I realize that every inner product defined on a vector space can give rise to a norm on that space.  The converse, apparently is not true.  I'd like an example of a norm which no inner product can generate. Word for a person with a negative attitude Armature keeps spinning around root bone in pose mode when I try to move anything I was following a tutorial on rigging (was pretty much done) and now my entire model keeps spinning around the main root bone if I try to move any bone at all. (first picture is where it originally was and still is while in Rest Position, second image is of how it changes when in Pose Position while in Pose Mode or Object mode, Edit Mode seems fine)    I tried clearing All Transforms or hitting the ALT+g, s, r while all were selected and that just caused it to spin in the same direction like everything else does as shown in this picture:   I was nearly finished with this video tutorial here,     and near the last part my issue began. 2:28:07 was the last time I was in edit mode and the pose was fine. Right after the little turrets he then went and parented 3 more bones and then he switches back to pose mode with no problem, I suspect somewhere in there is where the problem occurred on my end. I could have sworn I followed it correctly but maybe I went wrong somewhere I have no idea.   I couldn't find another issue like mine exactly so sorry if this question has been asked before, I'm still very new.  Edit: I checked in the video comments to see if it had happened to anyone else but I did not see any mention of it unfortunately.  Edit2: Picture for more detail on the yellow lines. "Goose"–"geese" vs. "moose"–"moose" Why is it that the plural of goose is geese but the plural of moose is moose? The same goes for mouse and house. Mouse becomes mice, yet house becomes houses. Difficulty in creating macro '\newcommand' for the beginning and end of frames in Beamer How do we know the brain flips images projected on the retina back around? Why do we turn images upside down again rather than dealing with them directly, still vertically rotated after passing through our lens?   I don't see how that would cause any problems, and how we'd ever be able to figure out if we are presented with flipped images after getting used to interacting based on visual input, whether flipped or not.   What am I missing? How can I further diagnose my central air conditioning compressor fan motor and capacitor? I have a 15 year old Bryant Central Air unit in my house.  Yesterday it stopped working.  Here is what I have checked.   The breaker in the basement is not tripped. The furnace works fine from the thermostat. The blower downstairs by the furnace runs when AC is on and blows room temp air into the house, but the fan on the compressor is not spinning.  The fan on the compressor does spin freely when I manually spin it with a stick.  Checked for fuses in the outside box.  There are no fuses outside, only an on/off pull thingy with two metal plates that you have to turn upside down to turn off. The capacitor is not flat on top, but far less rounded then any of the examples of blown AC dual capacitors I've seen on youtube. I get 220v in on the contactor. I get 220v out on the contactor. I get 24v from the thermostat. When the air is on at the thermostat the contactor solenoid is in, when the air is off it is out.   When the air is on at the thermostat I hear a buzz coming from the outside compressor but I can't tell what the source of the buzz is. If I push the solenoid in when the AC is off, the compressor does not start up and the fan does not spin, I just hear the buzz. If I wait by the compressor outside for a few seconds while the AC is on there's another buzz sound that goes off for about 3 seconds then stops.  From listening to the AC when it was working this is the buzz sound that goes off before the compressor and fan usually kick in. After leaving the non-functioning unit on for a few minutes while I diagnosed I noticed that the metal on top of the compressor fan motor was VERY hot to the touch.  It cooled after I turned the AC off.   I'm thinking the fan motor on the compressor is dead or the capacitor is bad.  Is there a way to check the capacitor and the fan motor while they're still in the unit?  With the power off of course.  Does anyone think it's something else?  Do I have to buy the overpriced ($485 for the manufacturer fan motor and $200 for the dual capacitor) replacement part from the manufacturer or can I use a third party manufacturer?  Any other help would be appreciated.  As much as I'd love to bring an HVAC guy in here I just can't afford it.  Either I go without AC, or I fix it myself.  EDIT:  With the AC on I manually spun up the fan on the compressor and the fan started spinning and the AC unit fired up. Counting overlapping polygons in GeoJSON to result in new set of polygons? Get the name of an object's type Is there a JavaScript equivalent of Java's class.getName()? How to create SHA512 password hashes on command line In Linux I can create a SHA1 password hash using sha1pass mypassword. Is there a similar command line tool which lets me create sha512 hashes? Same question for Bcrypt and PBKDF2.