Can I visit London with a US visit visa during a 11 hours lay over at LHR? I hold an Indian passport and I am flying to Seattle, US from Bangalore, India via LHR, London and the layover is 11 hours. Can I visit London with the US visit visa I have (this is accepted in many countries I heard)?  Do British Airways provide any help in this kind of situation either to visit or stay comfy at airport?
Is there a way to find out if I need a transit visa for a layover in the UK? Is there a website or some other way to find out if I need a transit visa for a short stop in the UK on my way somewhere else? Ideally this should give me the answer for all nationalities, and take into account any other visas I may have.
Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException Combining two covariance matrices I've implemented AStar in Java and it works ok for an area with obstacles where the chosen destination is reachable.  However, when the destination is unreachable, the calculated "path" is in no way to the closest location (to the unreachable location) but is instead some random path.  Is there a feasible way to tweak AStar into finding the path to the closest location to an unreachable destination? As I'm learning about iptables I've made a couple of mistakes and locked myself out.  What method(s) do you use to test rules without locking yourself out?  I'm using ubuntu server 12.04 LTS    All the answers below were helpful.  In the end I used a combination of options.  It also helps to have IPMI access to your remote server just in case!  But ideally test the rules locally on a replicated environment and test that first.  Vagrant helps in this regard to get test setups working quickly. optimality of the Carnot cycle It is well-known and is stated always and everywhere that the Carnot cycle is the most efficient thermodynamic cycle. Although stated as such it is rarely proven. One proof is in the article &quot;Engine Efficiencies and the Second Law of Thermodynamics&quot;, (AMERICAN JOURNAL OF PHYSICS VOLUME 37, NUMBER 11 NOVEMBER 1969), Tobin proves that among all engines performing a cycle, so that the engine returns to its starting state, the Carnot cycle is the most efficient where efficiency is defined as $\epsilon= 1-\frac{Q_{rejected}}{Q_{absorbed}}$, and the Carnot cycle is defined as one consisting of an isothermal-adiabatic-isothermal-adiabatic segment. The proof assumes the Clausius equality, that is in a reversible cycle $\oint \frac{\delta Q}{T} = 0$. Then using the geometry of the picture below a simple argument over the areas enclosed in the cycles IABCDJI vs. IAEFGDJI (heat absorbed) or IJDAI vs. GHEAIJDG (heat rejected) will show that any other cycle working between the same temperature limits such as EFGHE will have lower efficiency than the Carnot cycle ABCDA. But this proof assumes tacitly that pieces EFG and GHE are such that $dS&gt;0$ and $dS&lt;0$, respectively. Here I am thinking of a nasty cycle such as shown in the next figure in red where the cycle cannot be neatly separated into two and only two monotonic parts having $dS&gt;0$ or $dS&lt;0$. There is no obvious reason why that restriction should hold in general. Clearly this monotonicity should hold if the engine has only temperature as its independent &quot;force&quot; but if the engine's state needs more than one independent force variable than the situation is more complicated. Instead it is reasonable to assume that any physical cycle should have finite number of monotonic pieces, kind of a &quot;thermodynamic Dirichlet condition&quot; but it could also have self intersections, little loops, and other ugly features when projected on the TS plane. How would then one prove the optimality of a Carnot cycle? Or ugly cycles on the ST plane are non-physical even if there are more than one thermodynamic variables? [] [] What is the proof that given a set of $n$ elements there are $2^n$ possible subsets (including the empty-set and the original set). Opposite of "straight talk" What is the opposite for the straight talk idiom? How do I best call the activity when someone makes a very long preamble before he says what he wants? The Start menu no longer shows up when I press the Start button Are Mersenne prime exponents always odd? I have been researching  so I can write a program that finds them. A Mersenne prime looks like $2^n-1$. When calculating them, I have noticed that the $n$ value always appears to be odd. Is there confirmation or proof of this being true? meaning of the word "in" in context It is from . It is at around 8 minute and 39 second. Here it goes:     Culinary cultural fusion is all the rage; more novels translated from languages then ever before, although few are read, and in the surest sign of cultural globalization, football, the world's game, finally has reached America.   I guess the sentence would make sense if the preposition in were dropped out. Could you please tell me what did the host use it for? Is storing passwords hashed with the email more secure than without? If I enter the US by land, not needing ESTA, would I then need ESTA to enter by air 3 days later? I am a UK citizen, and therefore qualify for the USA's  (VWP). If I enter by  I need to apply for (and pay for) ESTA beforehand. If I enter by , I don't need ESTA. But I do get a 90 day visa waiver which allows me to go to Canada and return to the USA, on the same VWP.   My question is: If I first enter the USA on foot, from Canada (at Niagara Falls), return to Canada on foot, and then 3 days later fly from Canada into the USA, do I need ESTA? Or as my existing visa waiver is still in place, is that good enough? How can I redirect the user from one page to another using jQuery or pure JavaScript? Field between the plates of a parallel plate capacitor using Gauss's Law Why is fundamental group insufficient to classify manifolds? Let $f$ be a measurable function on a measure space $X$ and suppose that $fg \in L^1$ for all $g\in L^q$. Must $f$ be in $L^p$, for $p$ the conjugate of $q$? If we assume that $\|fg\|_1 \leq C\|g\|_q$ for some constant $C$, this follows from the Riesz Representation theorem. But what if we aren't given that such a $C$ exists? What is an "index out of range" exception, and how do I fix it? Given (p ∧ q), use the Fitch system to prove (q ∨ r) I'm having trouble solving a Fitch Style Proof and I was hoping someone would be able to help me.  Premises: p ∧ q  Goal: q ∨ r  Would be an assumption (p ∧ q => q ∨ r) in first step a correct one?   Then, q ∨ r Implication Elimination: 2, 1  Why is it not correct?  Thank you very much for any help! Proving $\gcd \left(\frac{a}{\gcd (a,b)},\frac{b}{\gcd (a,b)}\right)=1$ How would you go about proving that $$\gcd \left(\frac{a}{\gcd (a,b)},\frac{b}{\gcd (a,b)}\right)=1$$  for any two integers $a$ and $b$?  Intuitively it is true because when you divide $a$ and $b$ by $\gcd(a,b)$ you cancel out any common factors between them resulting in them becoming coprime. However, how would you prove this rigorously and mathematically? How do I completely remove an image from my .blend file?