Water Pressure Fluctuating
Why does my water pressure fluctuate?
The usual example of unitary ring without the  property is the ring of column finite matrices, and in this case we have $R\simeq R^2$ as (left) $R$-modules. (See also .) In particular, we have $R^2\simeq R^3$.      I wonder if there is an example of unitary ring (without the IBN property) such that $R^2\simeq R^3$, but $R\not\simeq R^2$ (as $R$-modules). Linux command line. Move all files and directories in directory, except some files and directories I have a folder A which has files and directories, I want to move all those files and directories to another folder B, except file, file2, directory, and directory2.  How can this be done? I am running centos 5.8 with cpanel. Lately I am getting reports that my swap is full , but there is a lot of free memory  to use.  top - 10:33:43 up 133 days, 17:00,  1 user,  load average: 0.05, 0.03, 0.05   Tasks: 170 total,   1 running, 169 sleeping,   0 stopped,   0 zombie   Cpu(s):  2.1%us,  0.5%sy,  0.0%ni, 97.2%id,  0.0%wa,  0.0%hi,  0.2%si,  0.0%st   Mem:  24726100k total,  8255368k used, 16470732k free,   599560k buffers   Swap:  1046520k total,   984740k used,    61780k free,  3641828k cached     How do I solve this? The unused ram memory should be used instead of the swap. Or should I increase the swap ( and how do I do that ? ).  Thanks SSH tunneling error: "channel 1: open failed: administratively prohibited: open failed" When I open this ssh tunnel:  ssh -nXNT -p 22 localhost -L 0.0.0.0:8984:remote:8983   I get this error when trying to access the HTTP server running on localhost:8984:  channel 1: open failed: administratively prohibited: open failed   What does this error mean, and on which machine can you fix the problem? Easy way to switch default sound output device Citation: refer to author or paper? What is the British English way of referring to a source in-text.  Is it plural because there are two authors, like this:         X and Y (2011) describe ...   Or is it singular because you are referring to a singular source, like this:     X and Y (2011) describes...   So what I am asking is whether you refer to the source or to the authors? How to get the CPU cycle count in x86_64 from C++? Why is propagation of uncertainties quadratic rather than linear? 1) Up until now, during practical work sessions, I always used these formulas for uncertainty propagation:  if $C = A+B$  or  $C = A-B$ $$\Delta C = \Delta A + \Delta B$$ if $C = AB$ or $C = \frac{A}{B}$ $$\frac{\Delta C}{C} = \frac{\Delta A}{A}  + \frac{\Delta B}{B}$$ if $C = A^m$ $$\frac{\Delta C}{C} = |m|\frac{\Delta A}{A}$$   These formulas are derived from the expression for the differential of a function of multiple variables:  if $C = f(A,B)$ $$ dC = \frac{\partial C}{\partial A}dA + \frac{\partial C}{\partial B}dB \Rightarrow \Delta C = \frac{\partial C}{\partial A}\Delta A + \frac{\partial C}{\partial B}\Delta B$$  and I think that makes sense because the value C is just a function of two variables that happen to be measurements.  2) But this morning, I was told that this is wrong and I should actually use these instead:  if $C = A+B$  or  $C = A-B$ $$(\Delta C)^2 = (\Delta A)^2 + (\Delta B)^2$$ if $C = AB$ or $C = \frac{A}{B}$ $$\left(\frac{\Delta C}{C}\right)^2 = \left(\frac{\Delta A}{A}\right)^2  + \left(\frac{\Delta B}{B}\right)^2$$  which are apparently derived from a general formula:  $$(\Delta C)^2  = \left(\frac{\partial C}{\partial x_1}\Delta x_1\right)^2 + \left(\frac{\partial C}{\partial x_2}\Delta x_2\right)^2 +   \hspace{0.3cm}...$$  or   $$\Delta C  = \sqrt{\left(\frac{\partial C}{\partial x_1}\Delta x_1\right)^2 + \left(\frac{\partial C}{\partial x_2}\Delta x_2\right)^2 +   \hspace{0.3cm}...}$$  3) So:   Why is this formula better?  Where does it come from? What does it actually represent? (Do I recognize the shape of a norm in that last formula?)  What is wrong with the formula of the differential?   I'm asking a lot, but the propagation of uncertainty always confused the ship out of me. iPhone with broken home button is stuck on black screen after jailbreaking Science fiction story where a colonist is sent by a company to colonize a planet and there a robot tries to sell him a depilating liquid by pulling a gun on him. The company who sponsored his trip to the new planet is extorting him by charging him exorbitant rates for anything they declare is not considered by them as bare necessities. The robot and man collaborate to get from the company the fair deal he deserves. The command history between sessions is not getting saved. I'm using guake and the history for the session is working fine. I noticed that .bash_history had some commands I executed in sudo -s mode and tried the same again and all the commands while in the session got saved so I tried: chmod 777 .bash_history  Now the old commands appear at the start of a session but no new commands are getting saved. Using dynamic where clauses in Entity Framework How can I convert the binary string $x_bin="0001001100101" to its numeric value $x_num=613 in Perl? How to run 32-bit app in Ubuntu 64-bit? I installed Ubuntu 14.04 and the current Android development SDK, which contains 32-bit executables. I found that I cannot run those 32-bit binaries. Trying to start them from bash gives me an error: $ ./adb bash: ./adb: No such file or directory  It is there though: $ ls -al ./adb -rwxrwxrwx 1 thomas thomas 1231255 Jan 17 13:31 ./adb $ file ./adb ./adb: ELF 32-bit LSB  executable, Intel 80386, version 1 (SYSV), dynamically linked (uses shared libs), for GNU/Linux 2.6.8, not stripped.   Same symptom for all the other 32-bit tools in the Android SDK. In olden days one could just install 32-bit libraries on 64-bit Ubuntu to get 32-bit support, but that does not seem to work anymore. How do I run 32-bit apps on a 64-bit Ubuntu distribution? Why is Excel truncating my 16-digit numbers? If I type in a 16 digit number (format: number, no decimals) it changes the number on me. Example: 1234567812345678 changes the view to 1234567812345670.    If I type it in as a general format it changes the numbers above so it displays 1.23457E+15 but if you click on the cell, the display shows the last digit as a 0 instead of an 8 once again.   I opened the file on a different computer and same issue now with it.  I have changed the auto correction and auto formatting all to no avail.  Help! I have a class with two class methods (using the classmethod() function) for getting and setting what is essentially a static variable.  I tried to use the property() function with these, but it results in an error.  I was able to reproduce the error with the following in the interpreter: class Foo(object):     _var = 5     @classmethod     def getvar(cls):         return cls._var     @classmethod     def setvar(cls, value):         cls._var = value     var = property(getvar, setvar)  I can demonstrate the class methods, but they don't work as properties: &gt;&gt;&gt; f = Foo() &gt;&gt;&gt; f.getvar() 5 &gt;&gt;&gt; f.setvar(4) &gt;&gt;&gt; f.getvar() 4 &gt;&gt;&gt; f.var Traceback (most recent call last):   File &quot;&lt;stdin&gt;&quot;, line 1, in ? TypeError: 'classmethod' object is not callable &gt;&gt;&gt; f.var=5 Traceback (most recent call last):   File &quot;&lt;stdin&gt;&quot;, line 1, in ? TypeError: 'classmethod' object is not callable  Is it possible to use the property() function with @classmethod decorated functions? Will store bought chicken eggs hatch? How can I add a PPA from a previous release? biblatex and new line for DOI, URL and Eprint How often do publishers sue researchers for copyright infringement for putting their articles on a personal website? I know that some publishers sometimes send copyright infringement emails to researchers putting their articles on a personal website. How often do publishers actually sue researchers for copyright infringement for putting their articles on a personal website? (assuming the authors didn't have the legal right to do so)  I am mostly interested in United States-based authors, but I am curious about other countries as well.