How to convert 160 digit binary string to 20 byte array?
In Java, how do I convert a byte array to a string of hex digits while keeping leading zeros?
London Heathrow airport - do I need a transit visa? I am traveling from the US to India via London Heathrow on November 6. I will be at LHR on 7th at 6:20 am and departing at 9:25 pm. I'm an Indian national and have a valid US visa.  Do I need a transit visa to stay airside?  I have been scared that British Airways have stopped a few people from boarding flights (no details just rumors).  Do I need a transit visa to stay landside? I want to do some sightseeing. What are the chances of getting past officials using transit without visa concession?  Real stories will help a lot to calm the butterflies in my stomach. How to open pdf file in Windows Phone 8? Tangent and Normal lines that pass through the origin Let $\alpha$ be a regular curve in $\mathbb{R}^2$ and let all of its tangent lines pass through the origin. Also, let $\beta$ be a regular curve in $\mathbb{R}^2$ and let all of its normal lines pass through the origin.   How can I show that $\alpha$ is contained in a straight line through the origin and that $\beta$ is contained in a circle around the origin?  I know that the tangent line $\alpha(t)$ is the line that points in the direction of the tangent vector $T(t)$ and that the normal line of $\beta(t)$ is the line that points in the direction of $N(t)$, but how can I put this all together to complete the proof? How do you calculate the probability density function of the maximum of a sample of IID uniform random variables? Given the random variable  $$Y = \max(X_1, X_2, \ldots, X_n)$$  where $X_i$ are IID uniform variables, how do I calculate the PDF of $Y$? Let $a=p_1^{x_1}p_2^{x_2}\cdots\cdot p_q^{x_q}$ and $b=p_1^{y_1}p_2^{y_2}\cdots p_r^{x_r}$ ,   say — Since gcd(a,b) is the largest common divisor of a and b and is divisible by any other common divisor of the two,   GCD$(a,b)=p_1^{\min(x_1,y_1)}p_2^{\min (x_2,y_2)} \cdots p_q^{\min (x_q,y_q)}$  LCM$(a,b)= p_1^{\max(x_1,y_1)}p_2^{\max(x_2,y_2)}\cdots p_r^{\max (x_r,y_r)}$  I understand GCD(a,b) has to divide both $a,b$. Therefore the exponent of any prime factor $p_i$ in GCD has to be in both $a,b$  — therefore $p_i^{\min(x_i, y_i)}$. But I'm muddled and anxious. Why does $\min$ appear in GREATEST common divisor? Why does $\max$ appear in LOWEST common multiple? Why do we tag questions? My question—my meta-question as the case may be—concerns the purpose of these words referred to as "tags". Let me be clear: I use tags. The site supports them, so why shouldn't I? My understanding of their reason for existing is tragically incomplete.   Are they used for searching? Are they useful in any other way, or do they merely act as decoration?     For more information, see "" and "" in the . How to mass rename files with ill-formed numbering? Are $(x^3)^{1/3} $ and $\sqrt{x^2}$ monomials?    In mathematics, a  is, roughly speaking, a polynomial which has only one term. Two different definitions of a monomial may be encountered:  For the first definition, a monomial, also called power product, is a product of powers of variables with nonnegative integer exponents, or, in other words, a product of variables, possibly with repetitions.   For the second definition, a monomial is a monomial in the first sense multiplied by a nonzero constant, called the coefficient of the monomial. How to change from csh to bash as default shell I have csh as my default shell, as shown by echo $SHELL. I want to switch to bash as my default shell. I tried the following approaches to no avail:   With chsh I get:  chsh: can only change local entries; use ypchsh instead.  With ypchsh I get:  ypchsh: yppasswdd not running on NIS master host ("dcsun2").    I only have .chsrc in my home directory and I cannot find any .profile files in /etc. How can I change my default shell to bash? I want to upgrade the hard drive in my 2012 Macbook Pro to an SSD. I have the parts, but had a question about how to clone the contents of my current drive so I can install it onto the SSD.  I've seen tutorials where people suggest connecting the new SSD to the Macbook prior to installation and using a Carbon Copy Cloner to clone the drive, and then installing the SSD drive.  My question is, can I do a Time Machine backup of my current hard drive on an external hard drive, install the SSD, and then use the Time Machine backup from the external to transfer it onto the newly installed SSD? Is this the same as using the clone program above? iOS 9.2 double touch fingerprint sensor Novel about a teleportation device and a con artist alien I haven't filed 2020 taxes yet. On my last return (2019) my adult daughter was on my return as a dependent. When I file 2020, I will not put her on my return as a dependent, because she finished college in 2019. I had her file her 2020 return early this year so she would be sure to get a stimulus check in case they did another one (I assumed they would exclude adult dependents as they had with previous stimulus payments). Today, she got the $1,400 deposited to her account by the Treasury. However, I was surprised to see $4,200 deposited to my account, when I expected only $2,800 (for me and my wife). They paid for my daughter twice, $1,400 to her (based on her 2020 return) and $1,400 to me (based on my 2019 return that showed her as a dependent). They have the social security numbers, so I assumed the IRS and Treasury would have figured this out. I have searched and searched, but am unsure whether this overpayment will be clawed back or not. I can't even find a mechanism for returning it (and getting credit for doing that if they later do say I owe it to them). I've read if your 2019 income made you eligible, but your 2020 income (if you file after the stimulus) would have made you ineligible, they won't claw back the stimulus they sent. Stimulus money for people that died between the tax return and the stimulus disbursement does have to be returned to the treasury. I can't find guidance for our situation. There must be a fair number of people with college kids that have the same scenario. This question  seems at first to ask the same thing, but it doesn't include the key point of overpayment by the Treasury. How does the standard error work? I have been looking into the inner-workings of the standard error recently, and I found myself unable to understand how it works. My understanding of the standard error is that it is the standard deviation of the distribution of sample means. My questions are:  • how do we know the standard error is the standard deviation of the sample means when we usually take just a single sample?  • why doesnt the equation to calculate the standard error mirror the standard deviation equation for a single sample? Can I get the "Diamonds to you!" achievement in singleplayer? How can one get the "Diamonds to you!" achievement in singleplayer? The achievement list cannot be completed without it. Perhaps it can be possible by passing a diamond to a zombie? biblatex - issue number of journal in date In (non-relativistic) classical physics, if the temperature of an object is proportional to the average kinetic energy ${1 \over 2} m\overline {v^{2}}$of its particles (or molecules), then shouldn't that temperature depend on the frame of reference - since $\overline {v^{2}}$ will be different in different frames?  (I.e. In the lab frame  $K_l = {1 \over 2} m\overline {v^{2}} $, but in a frame moving with velocity $u$ relative to the lab frame, $K_u =  {1 \over 2} m \overline {(v+u)^{2}}$). Given the Lie algebra, what is the systematic way to construct the matrix representation of the generators of the desired dimension? I ask this question here because it is the physicists for whom representation of groups is more important than mathematicians.   Let us, for example, take $SU(2)$ for concreteness. Starting from the generic parametrization of a $3\times 3$ unitary matrix $U$ with $\det U=1$, and using the formula of generators $$J^i=-i\Big(\frac{\partial U}{\partial \theta_i}\Big)_{\{\theta_i=0\}}$$ one can find the $3\times 3$ matrix representation of the generators.  However, I'm looking for something else.    Given the Lie algebra $[J^i, J^j]=i\epsilon^{ijk}J^k$, is there a way that one can explicitly construct (not by guess or trial) the $3\times 3$ representations of $\{J^i\}$? Will the same procedure apply to solve other Lie algebras appearing in physics such as that of $SO(3,1)$ (or $SL(2,\mathbb{C})$)? How to install qt 4.8 from repository? Calculating the total number of surjective functions