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Do gravitational waves slow down as they pass through matter? I've heard that gravitational waves travel at the speed of light, and have some parallels to electromagnetic waves.  EM waves slow down as they pass through matter (speed of light in glass is slower than in vacuum, for instance).  Do gravitational waves also slow down as they pass through matter?  If so, are there any effects like  when matter passes through a medium at a speed greater than the velocity of gravity in that medium?  Do large masses like stars or Jupiter act as ball lenses for gravitational waves? What does the Visual Studio "Any CPU" target mean? The use of nominative "whom" (as in “persons whom it is foreseeable are likely to...”) Recently I'm working on a project aiming to convert the vibration of sound waves into electricity to charge batteries using a piezoelectric material (MFC type). I was trying to use the human voice as an input, but theoretically it was not enough, so do you have any ideas about some places that I can apply my project on it (that must be noisy or can give me vibrations)?  Moreover, has the MFC material been used before in this application? If I used many pieces of it in parallel would that help? $2 \times 2 $ Orthogonal Group I am trying to prove that $O(2)$ has two connected components. This is what I have done: Suppose $A \in O(2)$. Then $A^tA=I$, where $A^t$ is the transpose of $A$ and $I$ is the identity. Taking the determinant of both sides of this equation, we get $\det(A^t)\det(A) = (det(A))^2$   which implies $\det(A) = \pm 1$.  And since $\det$ is continuous (which means that the inverse image of an open set is open), we have $O(2)$ is the disjoint union of $O^+(2)$ and $O^-(2)$. Is this right? Would this be sufficient or would this only prove that there are at least two components? Are $10\times 10$ matrices spanned by powers of a single matrix? I don't know how to answer this question:     Is there a $10 \times 10$ matrix $A$ such that $$M_{10}(\mathbb{F})=\text{span}\{I,A,A^2,\ldots, A^{100}\}\textrm{,}$$ where $M_{10}(\mathbb{F})$ is the vector space of $10 \times 10$ matrices over $\mathbb{F}$?   I think there is a connection to Jordan normal form. I am interested in good integer approximation from below and from above for binary Log(N!).  and  provides only a general idea but not exact values. In other words I need integers A and B so that  A &lt;= Log(N!) &lt;= B Duplicity Backup Browse Invalid characters for XML parsing in posthistory.xml from Stack Overflow We got the April 2011 data dump from Stack Overflow and, while trying to put everything into a database, we got      SyntaxError: reference to invalid character number: line 1105549, column 5445   in the middle of the posthistory.xml file. It seems that there are sets of characters (&amp;#xC I believe) within a few posthistory entries which break our XML parser.  Is there a solution besides manually changing all the C's? How to assign a function in Lua for a randomly generated numbers Align multiline equation with expression after equal sign I am trying to align a multiline equation using array within the equation but it turns out it doesn't do very well. The code I am using is as follows:  \begin{equation}    \begin{array}{lcl} \mathcal{L}^{-1}\left\{f(d)\right\} &amp;= \mathcal{L}^{-1}\left\{f_1(\delta).f_2(\delta)\right\} \\ &amp; = exp(mt) \star \left\{\frac{l}{2\sqrt{\pi t^3}} exp(-l^2/{4t})\right\} \\ &amp; = F_1 * F_2 \end{array} \end{equation}   Can anyone suggest better way to deal with it ? What changes with Kerberos authentication in IPv6 when everyone has a public IPv6 Address? How should Kerberos authentication be set up with IPv6?     What implications are there when client devices each use a public, globally routeable IPv6 IP address?  What changes when setup this way instead of using a NAT as was the norm with IPv4? Any way to control light halos in the compositor based on emission level? I am wanting to animate a row of LED lights. I have separated the LED lights from the rest of my object with the pass index/ID mask functions; currently all of my LED lights are on pass index #1.  What I want is to have a minor halo effect around the lights, but only when they are active. Currently, when I add a halo effect to my pass index #1, all of the LED lights have a halo effect regardless if the LEDs are emitting light. All LEDs are diffuse and emission shaders, so I can animate by controlling the mix amount between diffuse and emission.   Is there any simple way to have the halo effect created through recognizing light emission values, or will I have to just animate each LED as its own layer of compositing? How do you compile OpenSSL for x64? After following the instructions in INSTALL.W64 I have two problems:   The code is still written to the "out32" folder. I need to be able to link to both 32-bit and 64-bit versions of the library on my workstation, so I don't want the 64-bit versions to clobber the 32-bit libs. The output is still 32-bit! This means that I get "unresolved external symbol" errors when trying to link to the libraries from an x64 app. How to process a multi column text file to get another multi column text file? I have a text file:  a   aa  aaa     b   bb  bbb     c   cc  ccc d   dd  ddd     e   ee  eee     f   ff  fff g   gg  ggg     h   hh  hhh     i   ii  iii j   jj  jjj   How can I process it and get a 2 column file like this:  a   aa aaa b bb  bbb c   cc ccc d dd  ddd e   ee eee f ff  fff g   gg ggg h hh  hhh i   ii iii j jj  jjj   Or a three column file like this:  a   aa  aaa b   bb  bbb c   cc  ccc d   dd  ddd e   ee  eee f   ff  fff g   gg  ggg h   hh  hhh i   ii  iii j   jj  jj   I prefer to get awk solution but other solutions are welcomed too. Query Which Profiles Have Read Access To Specific Object? Since I couldn't think of how to write this query off the top of my head, I thought it might be worth sharing. How can I query which Profiles have Read permission on a specific object? I knew it would have something to do with ObjectPermissions and PermissionSet, but had to look up the documentation for both to piece it together. I see in my company's IT installations that there are numerous disks with one partition occupying all of the space on disk. There is typically something like a /dev/sdb with a partition /dev/sdb1, and the size of /dev/sdb1 is the size of the whole block device. The partition is then mounted with the required file-system format, mountpoint etc.  I do not understand why we would use a partition rather than the whole disk for such (1-partition) configurations. Is there any reason why a partition would be used in this case rather than a whole disk ? Are there any best practices that recommend this approach ?  For example, we could create a Filesystem on a whole raw block device and mount it without needing any partition:  mkfs.ext4 -E stride=16,stripe-width=64 /dev/xvde mount /dev/xvde /mnt/abc   That creates a mountpoint without a specified partition. As a verification:  # sfdisk -l /dev/xvde  Disk /dev/xvde: 6527 cylinders, 255 heads, 63 sectors/track  # fdisk -l /dev/xvde  Disk /dev/xvde: 53.7 GB, 53687091200 bytes, 104857600 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes   For something with a partition, we get the list of partitions under it:  # fdisk -l /dev/sdb  Disk /dev/sdb: 2000.4 GB, 2000398934016 bytes, 3907029168 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk label type: dos Disk identifier: 0x00082e8c     Device Boot      Start         End      Blocks   Id  System /dev/sdb1            2048  3907026943  1953512448   83  Linux   My fundamental question is this: Is there some advantage in creating a partition and then creating a filesystem on that partition, as compared to creating a filesystem on the whole disk and then mounting the whole disk ? Can magnets rotate infinitely? What is tail recursion? Can I increase the speed of combat? XCOM Enemy Unknown is a beautiful game, but you can only see every 5 second animation so many times before it becomes repetitive and self-indulgent. Is there a way to make the animations go faster or speed combat up in some other way, so that I can spend more time strategically exterminating aliens and less time watching my operatives shoot their guns?