Does "Invisibility" require sight to maintain concentration?
Can you maintain concentration on a spell from another plane?
The vast majority of intelligent species in the Star Trek universe are bipedal, humanoid creatures.  From the lot I've seen of TOS, TNG, DS9, Voyager, Enterprise, and the movies, it seems that this coincidence goes largely unquestioned.  Metaknowledge grants that it is much easier to have human actors portray human-like beings, and so this was probably done due to budgetary/technological limitations.  However, I'm wondering if an in-universe reason for this was ever given or explored? Looks like there is something wrong with reputation calculation:        +2*5 -6*2 = -2...   why there is +6 in reputation popup?  As @Catija said in comment calculation is OK in the profile:        Perhaps the issue is in the top-bar. "None is" or "none are" I was asked if the following sentences will create problems and what are the assumptions I have to make:  (d) There are grammarians in the room but none of them is an American. (e) There are grammarians in the room but none of them are Americans.  What is the problem in both sentences? They clearly have two main clauses which are connected by the coordinated conjunction 'but'. I know that grammar-wise, the 'is/are' don't really matter since both can be used with 'none', but would the tense in the first main clause 'are' affect the use of 'none'? Is there a way to find out if I need a transit visa for Canada? I'm passing through Canada, on my way to somewhere else. I'm staying only a short time.   Is there a website, or some other way of find out out if I need a visa? What are the summary rules for when to use image stabilization and when not to? When I got my DSLR, I took a lot of pics and all of them came excellent, even though I had VR at the "Off" position.   Since those came out so well, I wonder when should I turn VR on, and when I should just leave it off.   I found  which answer this question in detail, but that's too much for me to understand easily. Can someone explain the strict rules in short?  Should I use VR with tripod? When should I use it when I'm not using a tripod, and when should I leave it off? How to type en-dash and em-dash in Windows 7/8? I write blog posts, and I often need to type en-dash (–) and sometimes em-dash (—) in my blog posts. Currently I keep these characters saved in a text file, and copy-paste them whenever I need them. Unnecessary to say, it is a headache to move between keyboard and mouse when you type large texts.  It would be better for me if there ware a keyboard shortcuts available for these two characters. Is there a way to type en-dash and em-dash in Windows? I use Windows 7 and Windows 8 in different computers.    Here's an aligned comparison of dashes, if you need to see the difference for some reason.   Here's-dash Here's–en-dash Here's—em-dash Addons: Only some .zips will install Why is it that if I go to install an add-on from User Preferences > Add-ons > Install from File... and choose a *.ZIP, some add-ons will install, while others will return me to the User Preferences with nothing having happened (as far as I can tell)?  Is there a specific file structure required in the .ZIP? I get many add-ons from GitHub, using the Download Zip button, and even there installation of the actual Zip file only works some of the time. How to compile a function whose arguments are lists containing strings? There are many visa applicants who are working as an unregistered freelancer (photographer, construction contractor, fashion designer, journalist etc ). Some of these freelancers make really handsome monthly income and don't really need to work as a full time employee. Most of them receive variable amount of payments (cash, cheques, demand drafts etc) When it comes to filling a visa application form (USA, UK, Schengen etc), there is always an employment section in all visa form, eg for Schengen visa employment form :    This is a very important factor to make an application really strong.  Questions:   1 Unregistered freelancers can just simply write their profession? what documents to produce along with the application?  2 Bank statements with variable methods of payments could convince the visa officer that these are all legitimate payments? Evaluate $$\int \frac{2-3x}{2+3x}\sqrt\frac{1+x}{1-x}d x$$ What substitution should I use ? $\sqrt\frac{1+x}{1-x}$ suggests $x=cos2\theta $ but its not useful in $\frac{2-3x}{2+3x}$ Why is a normal subgroup of $G_1\times G_2$ with trivial intersections with $G_1$ and $G_2$ is abelian? Let $G=G_1\times G_2$ be a direct product, and let $H\triangleleft G$ be a normal subgroup such that $H\cap G_1=H\cap G_2=\{1\}.$ Then $H$ is abelian.     I considered the commutators of two elements in $H$, trying to show that it must be $1,$ but I don't see how this works. Any hint is very welcomed and appreciated. Thanks in advance. Agreement With Compound Subjects Joined by And Express $x^8-x$ as a product of irreducibles in $\Bbb Z_2[x]$ Express $x^8-x$ as a product of irreducibles in $\Bbb Z_2[x]$.  Work so far:  $$x^8 - x = x(x^7 - 1) = x(x - 1)(x^6+x^5+x^4+x^3+x^2+x+1)$$  From here, I think the Zeros of an Irreducible over a splitting field Theorem would be the method. I am unsure how to proceed I try to find a good proof for invertibility of strictly diagonally dominant matrices (defined by $|m_{ii}|&gt;\sum_{j\ne i}|m_{ij}|$).  There is a proof of this in  but I'm wondering whether there are are better proof such as using determinant, etc to show that the matrix is non singular. Black screen after suspend-after moving to the nvidia official drivers (not priority) Many C++ books contain example code like this...  std::cout &lt;&lt; "Test line" &lt;&lt; std::endl;   ...so I've always done that too. But I've seen a lot of code from working developers like this instead:  std::cout &lt;&lt; "Test line\n";   Is there a technical reason to prefer one over the other, or is it just a matter of coding style? Let $R$ be an rng. (There may be no unity)  Then, does there always exist a ring(with unity) $A$ such that $R$ is a subrng of $A$? Screen goes white when posting a comment Since iOS 11.2 all the way through 12.2 beta 4, if you post or discard a comment on any post on any SE community, the screen will turn white. This has been ongoing continuously for a year now, and it affects both the SE app and the SO app.   You can go back to the previous screen and open the question again, and everything appears as normal. You can also rotate the screen to get the text to come back. Using the arrows to navigate between the question and answers updates the HUD, but the screen remains white unless one of the above is done to get the text back.        UPDATE: After posting anything (comment, answer), the screen goes all white except for the sidebar. Perhaps it is intentional, but I prefer last week’s behavior of going back to the content. Not major, since the sidebar icons still work. Recommended books for advanced undergraduate electrodynamics What books are recommended for an advanced undergraduate course in electrodynamics? Do new wire runs in an existing ceiling need to be stapled down? I've heard some people say that code requires wiring in the wall to be stapled to framing every so often (how often?), but when you are doing a remodel, is that necessary?  I have a two story house, and would like to remove one standard dome light on the first floor ceiling and replace it with 6 recessed lights.  There is about 12" of empty space between the floors, and it seems easy enough to run the wire from light to light without cutting any drywall except for the 4-5" holes required for the lights. However, there's no way I'd be able to staple the wiring down.  It's just going to be loose in the ceiling, running through a small hole in the I joists every once in a while.  They sell "remodel" light cans that are made specifically so you only have to cut a hole big enough for them to fit in, so this seems like a common job.  What am I missing and how can I do this job in the most correct way?  This is in Dallas, TX, single family residence.