This article  talks about dunes visible on comet 67P:     In August, the European Space Agency (ESA) achieved a major success   when its Rosetta probe rendezvoused with comet 67P. The spacecraft has   been returning spectacular images of this strange little world,   located midway between the orbits of Mars and Jupiter. Among its   latest photographs is the image below showing what appear to be dunes   like those found on the deserts and beaches of Earth.     The comet would acquire an extremely thin atmosphere when it is close to sun. But this atmosphere would have very low density and would not produce winds as on earth.  So how can there be sand and small rocks on 67P?
What mechanism is responsible for the creation of these dunes on Comet 67P/Churyumov-Gerasimenko?  The following high resolution picture from ESA's Rosetta mission shows the dunes:       At a distance of 7.8 km from the surface, the image scale is about   66.5 cm/pixel, so each 1024 x 1024 pixel frame is about 680 m across (although if we assume the furthest point away is an additional ~1 km   further from the centre, the image scale is about 92 cm/pixel).   So the scale of the dunes is on the order of tens of meters along the crest. And each crest are probably just a few meters apart.
Is $\sum\limits_{n=1}^{\infty}\frac{n!}{n^n}$ convergent? I came to know about , it's a website that allow search for flights by country. I mean you just enter from like "Germany" and to like "Belgium" and you get best offers from all airports between the two countries. That is great. And I was able to arrange a good-price trip to Brussels.   Now I want to arrange another trip to Turkey, but Whichbudget is not helping much this time. And I can't find any other websites that allow "search by country".   Update: Not duplicate to  as his question is broad to the extent of a state. But my question is broad to the extent of a whole country + less price + "Any Time". If anyone checks , he'll understand what I'm saying. Especially that whichbudget allows "Any Time" option, not just +/-3 days.  Does anyone know more similar websites? 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I don't think even L'Hospital's rule can be applied . Please help . Thanks in advance When should I start the DLC? I'm late to the Borderlands 2 party, but I picked up the Season Pass for a steal.  I'm still only in the teens as far as my level is concerned.  However, there are now 3 DLC packs out and I've got them all installed.  Sometimes it's tempting to go away from the main quest and just jump into something new and potentially interesting.  In BL1, I played through the DLC between playthroughs of the game, treating the add-ons like continuations of the game post-final-boss.  I'm not sure if this is a good idea in BL2 (or even if it was smart in BL1, honestly...)  Is there a recommended level for starting the DLCs?  Will I encounter enemies that are too hard if I go early, or too easy if I go late?  Are there some weapons or quest rewards that I really can't get the most of until after I'm a certain level? 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I’d love to get a CD interest rate closer to what Ally or other online banks offer.   Are brick and mortar banks will to negotiate with customers on interest rates? For instance, if I went into a branch and said I’m moving my money to Ally unless the bank matches Ally’s rates, do I have any chance of getting them to? Prove $\gcd(a,b) \gcd(a,c) \gcd(b,c) \,\text{lcm} (a,b,c)^2=$ $\text{lcm}(a,b)\,\text{lcm}(a,c) \,\text{lcm}(b,c) \gcd(a,b,c)^2$ I'm trying prove $$\gcd(a,b) \gcd(a,c) \gcd(b,c) \,\text{lcm} (a,b,c)^2=\text{lcm}(a,b)\,\text{lcm}(a,c) \,\text{lcm}(b,c) \gcd(a,b,c)^2$$  It is a part of solution of another problem I try a lot to prove it but I could not be succeed.  I tried using exponent manipulation in prime factorizations but it didn't help me. Libraries module. Where to extract? Statement: There are uncountably many surjections from $\mathbb N$ to $\mathbb N$.  Is the following proof valid:  The real numbers are uncountable.   There exists a bijection between the set of real numbers and the set of all functions from $\mathbb N$ to $\{0,1\}$.   Given a function, $f$, from $\mathbb N$ to $\{0,1\}$, construct a surjection from $\mathbb N$ to $\mathbb N$, denoted $g$, as follows:  We map the $n$th composite number to $n$, and the nth prime, to $f(n)$.   Clearly this is a surjection since the composite numbers are countable. Clearly different functions $f$ lead to different surjections $g$. Since there are uncountably many $f$s, there are uncountably many surjections $g$. How does the Mac choose which connection to use when both Wifi and Ethernet are connected? When I'm connected to two networks with separate routers using Wifi and Ethernet, how does my Mac know what connection to use when I visit a website? Upgrade High-Trust Addin/App from 2013 to 2016 I have a SharePoint 2013 environment with several High-Trust Addins. This must now be upgraded to SharePoint 2016.  My Questions:   I was unable to find any documentation on the required steps. Links are welcome. Do i have to migrate App-Management Service and Subscription Settings Service?  don't even mention them.   say yes, but linked background is no longer available.  , i had to create a New-SPTrustedSecurityTokenIssuer. In this step, a RegisteredIssuerName had to be specified. This IssuerName consists of the Realm and the .   I think IssuerID can and should be migrated to SharePoint 2016, as it it also defined inside the High-Trust app. What about the Realm? This is by default the same value as FarmID. If i migrate this value, i have to change the Realm in SharePoint 2016. Or should i create the TST with a new Realm and existing IssuerID? I am stuck at my exam practice here.      The remainder of the division of $x^3$ by $x^2-x+1$ is ..... and that of $x^{2007}$ by $x^2-x+1$ is .....   I tried the polynomial remainder theorem but I am not sure if I did it correctly.  By factor theorem definition, provided by ,     the remainder of the division of a polynomial $f(x)$ by a linear polynomial  $x-r$ is equal to $f(r)$.   So I attempted to find $r$ by factorizing $x^2-x+1$ first but I got the complex form $x=\frac{1\pm\sqrt{3}i}{2}=r$.   $f(r)$ is then $(\frac{1+\sqrt{3}i}{2})^3$ or $(\frac{1-\sqrt{3}i}{2})^3$ which do not sound right.  However, the answer key provided is $-1$ for the first question and also $-1$ for the second one. Please help. Does the Google spider render JavaScript? When I execute a program without specifying the full path to the executable, and Bash must search the directories in $PATH to find the binary, it seems that Bash remembers the path in some sort of cache. For example, I installed a build of Subversion from source to /usr/local, then typed svnsync help at the Bash prompt. Bash located the binary /usr/local/bin/svnsync for "svnsync" and executed it. Then when I deleted the installation of Subversion in /usr/local and re-ran svnsync help, Bash responds:  bash: /usr/local/bin/svnsync: No such file or directory   But, when I start a new instance of Bash, it finds and executes /usr/bin/svnsync.  How do I clear the cache of paths to executables? QTimer can only be used with threads started with QThread Independence of disjoint events