Why doesn't my live USB save settings, even though I have a persistence file?
Why isn't persistence working on Lubuntu 12.04 Live-USB?
Why does parameter expansion with spaces without quotes work inside double brackets "[[" but not inside single brackets "["? Details on how the Yearling badge works Jawa asked me this  and I didn't know the answer. So I present it to the meta SO community:     [To get the Yearling badge] Do you need to earn the 200 rep within that one year or is it enough to get 200 at some point after being a member for a year? And does 'a year' mean the very first 12 months or the last (sliding window of) 12 months?    I would assume that if you hit 200 reputation after you've already been around for a year, then you would get the Yearling badge. But I don't know. USB composite device driver I am wondering if it possible to create a USB device (in following the device) composed from   a custom circuit (eg arduino) and  a flash storage   in such a manner that the device is recognized as a standard usb flash storage (and as such is operable with standart OS drivers), while said storage holds the utilities to operate with the custom circuit (dispalying the data colled by the circuit); and if so, how?  My first thought was to smack a cheap usb-hub and usb-pen before my circuit but that solution, is not pleasing to me.  My goal is to eliminate the need to carry an extra flash-drive just for the operating software, and use default os drivers, make it plug-and-just-work:   i plug the device in the os (windows) mounts a new flash-drive without needing a special driver is start (manually or via autorun) my custom.exe from that flash-drive i recive data measured by the circuit Salesforce DX daily limits As a package developer scratch orgs look like a great solution for automated CI testing and Salesforce has even done some great demos using Github and TravisCI to show automatically testing code using the DX CLI. However, in reviewing the details of DX, it looks like the limit is currently set to 50 orgs a day. If we want to test pull requests against 5 different org configurations, this limits us to 10 test runs a day. On a moderately sized team, this is going to be a tough limit to deal with. Has anyone had any success in working around this limit (or heard of any planned limit increases in the future). My initial thoughts are:   Get Salesforce to increase the limit (does not seem likely since this is a very young feature) Reuse scratch orgs for a period of time (this would require a good way to clean them and some savvy CI build code) Run fewer tests (not going to go over well the first time a bug for a specific org configuration slips through) I am flying to Tbilisi, Georgia with Turkish Airline. My stay in Istanbul is 12 hours. Can I get transit visa to visit Istanbul city ?    I am from Pakistan with Oman employment visa. What is the regular expression for a decimal with a precision of 2?  Valid examples:  123.12 2 56754 92929292929292.12 0.21 3.1   Invalid examples:  12.1232 2.23332 e666.76   The decimal point may be optional, and integers may also be included. jquery selector not working with [ ] Dates and times: "on", "in", "at"? I’m often confused when I speak about times and dates. What is the rule for using on, in, and at in the following sentences?   I will do it ___ Tuesday. We married ___ March. He returned ___ the same day. Every day ___ the same time, I walk the dog. Difference between $(this) and event.target? What length of rope should be used to tie a cow to an exterior fence post of a circular field so that the cow can only graze half of the grass within that field?  updated: To be clear: the cow should be tied to a post on the exterior of the field, not a post at the center of the field. How do I mention my own products in answers? Twice now I've seen questions on Stack Overflow where one of my company's products might provide an answer to the question.  One was a slightly vague connection about object-relational mapping, but the other was a specific question about workshop/event management where we have a product which is almost an exact match for the questioner's needs.  Of course the questioner should take a pinch of salt with anything I say about it, but it might be useful to have the product brought to his attention as one possible solution.  What are the rules and guidelines about answering with something I worked on? Shape with a slanted side (responsive) I can't seem to edit and save config files in the root system (eg: /etc/dhcp/dhcpd.config); it just says "permission denied" or the save option is blocked in the text editor.  I'm pretty sure I'm a root user, but how do I make sure? If I am a root user, how do I fix this? Why didn't Escobar's hippos introduced in a single event die out due to inbreeding Today I read a  about how Pablo Escobar had once imported 4 hippos (1 male, 3 female) into his estate in Colombia for his private zoo. After his downfall, while other species were shipped out, hippos were considered too big to move and expected to not survive. However, to the surprise of all the hippos are thriving and are so numerous that there have been calls to cull them. From the report:  Numbers are projected to only get bigger. [Colombian biologist Nataly] Castelblanco and her peers say the population will reach over 1,400 specimens as early as 2034 without a cull - all of them descended from the original group of a male and three females. In the study, they envisaged an ideal scenario in which 30 animals need to be culled or castrated every year to stop that happening.  My understanding is that since there was only 1 male, the gene pool would be limited and lead to lot of inbreeding in the descendants. This would cause population to not explode because some individuals would be unfit to survive. Why has this not happened in case of hippos? Is it because there are 3 females (probably unrelated to each other) which keeps gene pool large enough? Or can mutations explain this phenomenon? Would results have been different if originally 2 females had been moved and only 1 retained? EDIT - I have just found that  is maybe less than 100 individuals which though big is not massive. EDIT2 - I have edited the question title to keep focus on the hippos although a general answer would be welcome. Changing email addresses on my @me.com and @icloud.com Free visual similarity image for a local hard drive search? I'm looking for a desktop search engine for finding images on my local hard drive with high visual similarity. I've only found paid for ones so far. It could be Linux or windows one, either would be helpful.  A Google desktop plug-in would be nice! What would be the value of $\sum\limits_{n=0}^\infty \frac{1}{an^2+bn+c}$ I would like to evaluate the sum  $$\sum_{n=0}^\infty \frac{1}{an^2+bn+c}$$  Here is my attempt:    Letting    $$f(z)=\frac{1}{az^2+bz+c}$$  The poles of $f(z)$ are located at   $$z_0 = \frac{-b+\sqrt{b^2-4ac}}{2a}$$  and  $$z_1 = \frac{-b-\sqrt{b^2-4ac}}{2a}$$  Then  $$ b_0=\operatorname*{Res}_{z=z_0}\,\pi \cot (\pi z)f(z)= \lim_{z \to z_0} \frac{(z-z_0)\pi\cot (\pi z)}{az^2+bz+c}= \lim_{z \to z_0} \frac{\pi\cot (\pi z)+(z_0-z)\pi^2\csc^2 (\pi z)}{2az+b} $$  Using L'Hopital's rule. Continuing, we have the limit is  $$ \lim_{z \to z_0} \frac{\pi\cot (\pi z)+(z_0-z)\pi^2\csc^2 (\pi z)}{2az+b}= \frac{\pi\cot (\pi z_0)}{2az_0+b} $$  For $z_0 \ne 0$  Similarly, we find  $$b_1=\operatorname*{Res}_{z=z_1}\,\pi \cot (\pi z)f(z)=\frac{\pi\cot (\pi z_1)}{2az_1+b}$$  Then   $$\sum_{n=-\infty}^\infty \frac{1}{an^2+bn+c} = -(b_0+b_1)=\\ -\pi\left( \frac{\cot (\pi z_0)}{2az_0+b} + \frac{\cot (\pi z_1)}{2az_1+b}\right)=  -\pi\left( \frac{\cot (\pi z_0)}{\sqrt{b^2-4ac}} + \frac{\cot (\pi z_1)}{-\sqrt{b^2-4ac}}\right)= \frac{-\pi(\cot (\pi z_0)-\cot (\pi z_1))}{\sqrt{b^2-4ac}}= \frac{\pi(\cot (\pi z_1)-\cot (\pi z_0))}{\sqrt{b^2-4ac}} $$  Then we have  $$\sum_{n=0}^\infty \frac{1}{an^2+bn+c} = \frac{\pi(\cot (\pi z_1)-\cot (\pi z_0))}{2\sqrt{b^2-4ac}}$$    Is this correct?  I feel like I made a mistake somewhere.  Could someone correct me?  Is there an easier way to evaluate this sum? Suppose we have a set  $S=\{a,b\}.$ Obviously, the total number of binary operations on $S$ is the number of all the pairs such that $$*(a,b)=a \, \text{or}  \, b,$$ which gives  $ 2 \cdot 2 \cdot 2 \cdot 2=2^4$ possible ones. Is there a way to find which of these $16$ binary operations are associative without writing all the operation matrices and checking it by hand? "Most importantly" or "more importantly"? Which of the following two sentences is more correct?   "A picture says a thousand words, more importantly in a fraction of a second"    OR   "A picture says a thousand words, most importantly in a fraction of a second"   Nothing important, just my own quotes! Do also suggest, if I can put it in a better way to express what I want to. How to split bibliography into "works cited" and "works not cited"? I need two bib-like sections: a "References" giving works explicitly cited in my text, and a "Bibliography" (or "Further reading" if you prefer) giving everything from my bibfile that didn't already appear in "References". The first is of course completely standard, but the second... I'm stumped.  Further loose constraints: I'm somewhat committed to biblatex and the biblatex-apa style. But I'll happily accept an answer not related to them if there's any chance I can adapt it.