How can a disease be transmissible animal-to-human but not human-to-human?
Viruses: Adaptation to a new host through repeated host jumps
The title of  of  is, "Is it posible [sic]?"  This doesn't provide any information at all. It should be mandatory for everyone asking questions on the Internet to read , which says:     Help your community learn from the question. When you field a good question, ask yourself "How would the relevant documentation or FAQ have to change so that nobody has to answer this again?" List of all "partitions"/ "cuttings" of a list I've just made a minor alteration to a file from a TeX package.  I copied it into my local texmf tree and made the change there.  When I tried kpsewhich &lt;filename&gt; to test that it was finding my local version, it returned the original one and not the new one.  In actual fact, the original file was from my local texmf tree already so I renamed the old one something simple.  Now kpsewhich &lt;filename&gt; returned the system version of the file.  To check that the file was there, I tried kpsewhich -all &lt;filename&gt; and got the correct two versions of the file: my modified one and the system one (in that order).  If I try this with another file that I know exists in both places, then kpsewhich &lt;filename&gt; returns my local file.  Here's the various invocations and their results:  ~% kpsewhich pgfsys-pdftex.def /usr/local/texlive/2012/texmf-dist/tex/generic/pgf/systemlayer/pgfsys-pdftex.def ~% kpsewhich -all pgfsys-pdftex.def  /Users/stacey/Library/texmf/tex/latex/bzr/pgfsys-pdftex.def /usr/local/texlive/2012/texmf-dist/tex/generic/pgf/systemlayer/pgfsys-pdftex.def ~% kpsewhich tqft.sty               /Users/stacey/Library/texmf/tex/latex/bzr/tqft.sty ~% kpsewhich -all tqft.sty /Users/stacey/Library/texmf/tex/latex/bzr/tqft.sty /usr/local/texlive/2012/texmf-dist/tex/latex/tqft/tqft.sty   Is it something special about the .def extension?  Is there some command that I forgot to run?  Are there some other options to kpsewhich that will help me debug this? 2015 Macbook Air screen gradually dimming and dying This is not a problem at booting up. For a couple months now I'll be using my laptop when suddenly the screen dims to about 50% of normal. According to the brightness indicator the brightness is all the way up; I can make it dimmer, but not as bright as normal. The dimming isn't super even either, there are small areas of the screen that seem darker/brighter. In the past the problem easily goes away if I close the lid and reopen it... but now it's happening a lot and sometimes going completely black. Is this an easy/cheap fix? I'm traveling and can't do it myself. Is it worth bringing to the Mac store?  Thanks! Why can't a CNAME record be used at the apex (aka root) of a domain? This is a  about CNAMEs at the apices (or roots) of zones   It's relatively common knowledge that CNAME records at the apex of a domain are a taboo practice.  Example: example.com. IN CNAME ithurts.example.net.  In a best case scenario nameserver software might refuse to load the configuration, and in the worst case it might accept this configuration and invalidate the configuration for example.com.  Recently I had a webhosting company pass instructions to a business unit that we needed to CNAME the apex of our domain to a new record. Knowing that this would be a suicide config when fed to BIND, I advised them that we would not be able to comply and that this was bunk advice in general. The webhosting company took the stance that it is not outright forbidden by standard defining RFCs and that their software supports it. If we could not CNAME the apex, their advice was to have no apex record at all and they would not provide a redirecting webserver. ...What?  Most of us know that  insists that A CNAME record is not allowed to coexist with any other data., but let's be honest with ourselves here, that RFC is only Informational. The closest I know to verbiage that forbids the practice is from :     If a CNAME RR is present at a node, no other data should be   present; this ensures that the data for a canonical name and its aliases   cannot be different.   Unfortunately I've been in the industry long enough to know that "should not" is not the same as "must not", and that's enough rope for most software designers to hang themselves with. Knowing that anything short of a concise link to a slam dunk would be a waste of my time, I ended up letting the company get away with a scolding for recommending configurations that could break commonly used software without proper disclosure.  This brings us to the Q&amp;A. For once I'd like us to get really technical about the insanity of apex CNAMEs, and not skirt around the issue like we usually do when someone posts on the subject.  is off limits, as are any other Informational RFC applicable here that I didn't think of. Let's shut this baby down. Setup IIS 7.5 with multiple website bindings and SSL? On IIS 7.5 I am trying to achieve this with two websites:  Default Web Site is bound to:  (blank host header port 80 - http) (blank host header port 443 - https) go.example.com www71.example.com the IP address of go.example.com  2nd web site "Beta" is bound to:  beta.example.com (blank host header port 443 - https) * using blank only because it doesn't seem to be possible to    bind https to a named host header   And both need to work with SSL.  But I have these problems:   When I type in beta.example.com, I see the go.example.com site instead I can not seem to add the SSL binding to both websites at once (I have a single *.example.com wildcard certificate).  The beta site will not even start if I add the https binding to it.   This is how I have set it up:    What is the correct way to set it up? Excel How to make Text Qualifier editable or add a new entry in the existing list? How to find the kth largest element in an unsorted array of length n in O(n)? I believe there's a way to find the kth largest element in an unsorted array of length n in O(n).  Or perhaps it's "expected" O(n) or something.  How can we do this? How to solve this ode $xy''-(1+x)y'+y=x^2$? Is there a maximum possible acceleration? Calculator Program improvements I'm pretty new to programming and made a few programs so far. I recently made a Calculator program and I hope you guys could tell me what I could do to improve. int firstNumber; string sign; int secondNumber; int answer;  Console.WriteLine(&quot;Input Number:&quot;); firstNumber = Convert.ToInt32(Console.ReadLine()); Console.Clear();  Console.WriteLine(&quot;Input Sign:&quot;); sign = Console.ReadLine(); Console.Clear();  Console.WriteLine(&quot;Input Second Number:&quot;); secondNumber = Convert.ToInt32(Console.ReadLine()); Console.Clear();  switch (sign) {     case &quot;+&quot;:         answer = firstNumber + secondNumber;         Console.WriteLine(answer);         Console.ReadKey();     break;     case &quot;-&quot;:         answer = firstNumber - secondNumber;         Console.WriteLine(answer);         Console.ReadKey();     break;     case &quot;*&quot;:         answer = firstNumber * secondNumber;         Console.WriteLine(answer);         Console.ReadKey();     break;     case &quot;/&quot;:         answer = firstNumber / secondNumber;         Console.WriteLine(answer);         Console.ReadKey();     break;     default:         Console.WriteLine(&quot;Invalid Input&quot;);     break; } How can Kitty Pryde achieve time travel with her phasing abilities? In X-Men: Days of Future Past, how does Kitty Pryde suddenly get the power to send people's minds back in time? Initially she was only able to phase through objects and could extend this power to other people. The explanation of this cited molecular spaces.  How does she go from there to time travel all of a sudden?? A Python module and package loading confusion I have two separate Armatures that I want to join together. I have no problem combining the meshes, but the problem is the bones/rigs. When you do the Object mode > join, I lose all of my weight paint on one of my armatures. Is there any way I can join two separate armatures and keep all the weight paint. I turn my models into XPS and use XNA Lara to view them, but XNAlara cannot use both armatures at once. Using C++ library in C code How to know if my GPU supports CUDA? How can I know from the terminal or something whether my hardware supports CUDA? Is there a statement whose undecidability is undecidable? We know there are statements that are undecidable/independent of ZFC. Can there be a statement S, such that (ZFC $\not\vdash$ S and ZFC $\not\vdash$ ~S) is undecidable? How to avoid perceived circularity when defining a formal language? Suppose we want to define a first-order language to do set theory (so we can formalize mathematics). One such construction can be found . What makes me uneasy about this definition is that words such as "set", "countable", "function", and "number" are used in somewhat non-trivial manners. For instance, behind the word "countable" rests an immense amount of mathematical knowledge: one needs the notion of a bijection, which requires functions and sets. One also needs the set of natural numbers (or something with equal cardinality), in order to say that countable sets have a bijection with the set of natural numbers.  Also, in set theory one uses the relation of belonging "$\in$". But relation seems to require the notion an ordered pair, which requires sets, whose properties are described using belonging...  I found the following in Kevin Klement's,  (pages 2-3).  "You have to use logic to study logic. There’s no getting away from it. However, I’m not going to bother stating all the logical rules that are valid in the metalanguage, since I’d need to do that in the metametalanguage, and that would just get me started on an infinite regress. The rule of thumb is: if it’s OK in the object language, it’s OK in the metalanguage too."  So it seems that, if one proves a fact about the object language, then one can also use it in the metalanguage. In the case of set theory, one may not start out knowing what sets really are, but after one proves some fact about them (e.g., that there are uncountable sets) then one implicitly "adds" this fact also to the metalanguage.  This seems like cheating: one is using the object language to conduct proofs regarding the metalanguage, when it should strictly be the other way round.  To give an example of avoiding circularity, consider the definition of the integers. We can define a binary relation $R\subseteq(\mathbf{N}\times\mathbf{N})\times(\mathbf{N}\times\mathbf{N})$, where for any $a,b,c,d\in\mathbf{N}$, $((a,b),(c,d))\in R$ iff $a+d=b+c$, and then defining $\mathbf{Z}:= \{[(a,b)]:a,b\in\mathbf{N}\}$, where $[a,b]=\{x\in \mathbf{N}\times\mathbf{N}: xR(a,b)\}$, as in  question or  on Wikipedia. In this definition if set theory and natural numbers are assumed, then there is no circularity because one did not depend on the notion of "subtraction" in defining the integers.  So my question is:     Question Is the definition of first-order logic circular?   If not, please explain why.   If the definitions are circular, is there an alternative definition which avoids the circularity?   Some thoughts:   Perhaps there is the distinction between what sets are (anything that obeys the axioms) and how sets are expressed (using a formal language). In other words, the notion of a set may not be circular, but to talk of sets using a formal language requires the notion of a set in a metalanguage. In foundational mathematics there also seems to be the idea of first defining something, and then coming back with better machinery to analyse that thing. For instance, one can define the natural numbers using the Peano axioms, then later come back to say that all structures satisfying the axioms are isomorphic. (I don't know any algebra, but that seems right.) Maybe sets, functions, etc., are too basic? Is it possible to avoid these terms when defining a formal language? Assume the standard situation, that is, let $X_1, \ldots , X_n$ be independent and identically distributed with $X_k ∼ P_\theta(x; \theta)$ , where $P_\theta(x; \theta) = 2x/\theta^2$  if $0\le x \le\theta$ and $0$ otherwise. It is required to estimate $\theta$. Show that the maximum likelihood estimator for $\theta$ is $\hat{\theta} = \max{[X_1, \ldots , X_n]}$ and then show that the cumulative distribution function of $\hat{\theta}$ is $F_\theta(z) = z^{2n}/\theta^{2n}$. Here's what i did so far: Maximum Likehood estimator: $L_x(θ) = \prod_{i = 1}^{n} P_θ(x_k)$ Here we have $P_θ(x_1,...,x_n;θ) = P_θ(x_1,θ).P_θ(x_2,θ)...P_θ(x_n,θ)$ Likehood = $L_{x,θ}(θ) =P_θ(x_1,θ).P_θ(x_2,θ)...P_θ(x_n,θ)= 2x_1/θ^2. 2x_2/θ^2.. 2x_n/θ^2 = [2^n.\prod_{i = 1}^{n}x_i]/θ^{2n}$ Log-likehood: $\sum_{i = 1}^{n}log(P_θ(x_1,...x_n;θ))= \sum_{i = 1}^{n}log(2x_i/θ^2)$ Is this correct so far? Im still not sure how to get to $\hat{θ} = max{[X_1, . . . , X_n]}$ As for the the cumulative distribution part to show $F_θ(z) = z^{2n}/θ^{2n}$: $F(z) = P(max({x_k})&lt;z) = P(x_1&lt;z).P(x_2&lt;z)..P(x_n&lt;z) = 2x_1/θ^2.2x_2/θ^2...2x_n/θ^n = 2^n.\prod_{i = 1}^{n}x_i/θ^2n$ Not sure if this is correct. Would really appreciate some help. Edit: From the answers below, we can deduce the the estimator is biased. What estimator would be unbiased? How can i find it? File permissions and saving Let's say you open a file on which you have write permission. Meanwhile you change permissions and remove write permission while you still have the file open in some editor.  What will happen if you edit and save it?