Science fiction short story about lost group of mechanics
Abandoned colony of military engineer corps
Let $X_n$ be iid random variables with $P(X_n=(-1)^kk)=\dfrac{C}{k^2\log k}$ for all $k\geq 2$. Here $C$ is just a constant so that the sum of probabilities is $1$. Find constant $\mu$ such that $S_n/n\to \mu$ in probability where $S_n=\sum_{k=1}^nX_k$.   Here $E(X_n)=\infty$. I'm a bit lost after this. In general how does one find constants like this? I've added many PPAs using the add-apt-repository command. Is there a simple way to remove these PPAs? I've checked in /etc/apt/sources.list for the appropriate deb lines but they aren't there.   This is on a server system so a command line solution would be great! Can the Artificer Artillerist's tiny-sized Eldritch Cannon that is not held in hand still ride or be carried elsewhere on the body? Question Close Updates Usernames as Advertising or Spam? Stuff like polls, recommendations based on subjective constraints, puzzles, webcomics etc. do not belong on the serious main SE sites, where professionals should be considered at work and having just a few spare minutes ("code's compiling") to answer questions, so they should not be distracted by such things. However, I'd also like to have a home for these things still using the SE engine. For the reason I mentioned before, this needs to be a separate place though. Let's call it four.[sitename-here].com. Why are my Elytra Wings are not activating? Why do my Elytra Wings only work intermittently?  I do not forget to jump, but when I switch to Survival and then back to Creative, they won't activate whatsoever. Any help is much appreciated. Thanks. How to see the full date on macOS Big Sur? My Bash Prompt is currently setting the xterm titlebar using the following sequence:  PS1='\033]0;\u@\h&gt;\w\007'   Is there an easy way to display the current command in the titlebar. For example, if I am tailing a file using tail -f foo.log, I want my titlebar to say tail -f foo.log. I was thinking of the noted 1980 paper by Sidney Coleman and Frank de Luccia--"Gravitational effects of and on vacuum decay"-- about metastable vacuum states that could tunnel to a lower energy "true vacuum" with catastrophic results. I suspect the answer is that if our vacuum is a false one, we wouldn't "see" the true one til it hit us. For PhD applications, I have mentioned that I am interested in some research areas. Besides, I am thinking about mentioning some professors' names, so that it shows I have read their websites and I am not just sending out generic statements applicable to many schools.  But is it good to mention some professors' names in the statement of purpose, if I don't know them personally? In what cases is it good, and in what cases it isn't?  For example, is it good to only mention    those whose research directions are aligned with my research interests, or/and those whose books or notes I have heard of, or better, might have read some parts of, or/and those who are already established and famous (such as having certain titles), or/and those that are directing the PhD graduate programs, or/and those that are heads of the departments?    What will other professors who are not mentioned think? How will you do, if it were you? Solving $x^3-y^3=xy+61$ in integers I'm trying to solve the following equation:  $$x^3-y^3=xy+61$$  I got:  $$(x-y)(x^2+xy+y^2)=xy+61$$  But I can't go any further. I am looking for a solution in integers.  I need some hints to proceed, please! Gnome Panel becomes fully transparent when window is not maximised! "No root file system defined" error while installing ubuntu I am new to linux/ ubuntu and just downloaded the v11 of ubuntu to learn linux. I faced this "No root file system is defined" error while trying to install it. This is how I was proceeding -    Downloaded ubuntu v11 from the ubuntu.com website, wrote the iso into a bootable cd, and then got into the linux installation process on restarting; everything fine till here. In one of the screen during installation, there are three choices - install alongside windows, something else etc.. Since I have windows 7 in the C drive, I selected the first option - "Install alongside another OS".      Let me interrupt here to give my existing system details - HardDisk   size: 640GB.  Number of existing partitions - 5 C drive - label   windows - 160GB - has windows 7 installed D drive - label linux -   160GB - does not have any data E drive - label backup - 100GB - has   some data F drive - label entertainment - 100GB  - has some data G   drive - label work - 90GB  - has some data All of the above are in   NTFS format.    In the screen that follows, an image is shown with 2 parts and each part is shown to have size equal to 80GB. There is a horizontal slider in the middle of these two images, with which I can resize the partitions. The right side partition is labeled Linux. There is also an option to do 'advanced partitions'. On clicking advanced partitions on the above screen, a new screen is shown in which the partitions existing in my computer are shown - but the labels are different. I see that there are two partitions with size = 160GB each (as expected), and so I assumed that the first 160GB would be my existing C drive and the second on would be the partition which I had labeled as linux (drive D). So I selected the linux partition and clicked on proceed/ install now, and then this error was shown - "No root file system defined".. and I cannot proceed after this.   Please let me know two things here:   During the screen in point number 3 above, the image with slider was shown. Which partition (drive c: or d: or anyother) is being referred to here? Which one am I actually resizing - is it the existing c: drive which has windows 7 installed already, that is getting shrunk and then ubuntu getting installed in the remaining space? What does ""No root file system defined" error mean? How do I select the proper partition and continue with the installation?    P.S.:  I had already partitioned my drives as mentioned above, and the D drive with 160GB was specifically left free for installing ubuntu. I would like to Select D drive during setup and install ubuntu here, while still keeping the already installed windows7 in C drive.  Thanks! Why is time special? In Special Relativity, the spacetime interval between two events is $s^2 = -(c{\Delta}t)^2+({\Delta}x)^2+({\Delta}y)^2+({\Delta}z)^2$ giving the Minkowski metric $\eta_{\mu\nu}=\text{diag}(-1, 1, 1, 1)$. What is the justification for making time have a negative coefficient, and how closely is that related to the 2nd law of thermodynamics? Sure, by letting $\eta = \text{diag}(1, 1, 1, 1)$, we get a pretty boring spacetime, and the boosts in the Poincaré group become trig instead of hyperbolic functions, but what's the physical reasoning behind this? Tracking disk I/O by application in Windows? Is there a utility for Windows that operates similarly to iotop for Linux?  I'm looking for simple tool that can tell me what applications are writing to disk and how much they're actually writing. Dragging layer into new file changes its size Let's say I have a file that's 4'x12' and represents a space on an actual wall. I want to open certain files (of different sizes) and drag each file into the large file in order to arrange the images correctly on the computer before physically hanging the framed finals.  When I drag a new image into the larger file, the new image's size and the size of its copy don't match. That is, Say I drag an 8x10 into the large file, well on the large file (trying to control size with guides and rulers) the new image is some other size, but not the right one.   What am I doing wrong? How do I make sure that when I click and drag the new image that it will be properly represented? Why doesn't Mac OS X source ~/.bashrc? Why is it dangerous to initialize weights with zeros? Is there any simple example that demonstrates it? So I know that two particles can be entangled in a quantum way, but is it possible that more than two particles be entangled in a quantum way? Most descriptions provide with two-particles cases, so I wonder. (It's hard to think of three particles entangled in spin, or so.)