Is density of an element directly proportional to atomic number or atomic weight?
Why is the relationship between atomic number and density not linear?
If I call a command using  in Ruby, how do I get its output?  system("ls") I'm an Indian National. I have a Type C Schengen Business Visa which is valid from 26-11-2015 to 26-11-2020. I received it when I intended to travel to Netherlands, although I have not used it.   When I applied for a spouse endorsement, the passport on which the visa is stamped was cancelled and a new passport was issued.  Now, I plan to travel to Italy on business from July 8th to 16th.    Can travel with the same visa in old passport, or should I cancel the existing visa and apply for a new one?  I contacted the Netherlands Embassy call center (not VFS Netherlands) which responded that I can use it without any issues. However, they have not confirmed it by email.   I asked about any immigration issues in Italy and was told me that, if I have a valid itinerary and invitation letter from the office, there should be no problem. I was also told that Italian immigration authorities are able to contact the Dutch, if necessary.   I emailed the Italian Embassy in Mumbai (visa.mumbai@esteri.it) and await its response. The space $c_0$ of sequences that converge to 0 is not reflexive How do I render nodes, now that node_view() has been deprecated? In Drupal 7 I frequently use node_view() for rendering nodes (using view modes) in blocks or pages as follows:  $nids = array(123,456,789); $nodes = node_load_multiple($nids); foreach ($nodes as $node) {   $node_view = node_view($node, 'teaser');   $output .= drupal_render($node_view); } $build['nodes']['#markup'] = $output; return $build;   node_view()/entity_view() has been deprecated and replaced by a view builder as explained in change record . The information is not detailed enough for me to be able to figure out how to achieve the same result.  How can you render nodes in Drupal 8 so that the output can be used in the render array of a block or page? Salesforce query on profile not working on user language change I have a query on profile like  profilename = [Select name from profile where id=:userinfo.getUserprofileid ].name  Now I have a check in  VF page  like  profilename  == 'System Administrator' . this works fine if the logged in user language is english. If the user language is different then profile name will be  'System admin' in that language . So how to prevent this beahviour?   Also  is there any particular field in profile which I can use  to identify the profile is system admin? so that I can have check on that field instead of checking for name which is causing the problem, for example I think modifyall filed is only checked for system admin. The well-known fable of an astronaut sending signals out to an external observer while falling toward an event horizon states that the time lapse between such signals becomes greater even if in the astronaut sends them out periodically (as judged in his inertial frame). When viewed from earth and weighing time-dilation due to the gravitational field of the collapsing star, how is it possible that a black hole can form in finite time (for any external observer) if it takes an infinite amount of time to "see" events occurring at the event horizon? Black holes and positive/negative-energy particles I was reading Brian Greene's "Hidden Reality" and came to the part about Hawking Radiation. Quantum jitters that occur near the event horizon of a black hole, which create both positive-energy particles and negative-energy particles, produce the so-called Hawking radiation. However, I do not understand why only the negative-energy particles are being absorbed into the black hole, while the positive-energy particles shoot outward. Shouldn't there be 50/50 chance that each type of particle is being absorbed by the black hole? Also, the book mentions that a negative-energy particle would appear to an observer inside the black hole as positive. Why? I have two complete sentences; the second is in parentheses, essentially a comment on the first.  Where do I place the periods?  I would use this:     They played opera. (I covered my ears.)   Is this punctuation correct? Does the following series have a closed-form expression:  $$\sum_{k=0}^{\infty} \frac{z^k}{(k!)^2}$$  I know that it must converge because:  $$\sum_{k=0}^{\infty} \frac{z^k}{k!} = e^z$$  and the $(k!)^2$ denominator obviously increases more quickly than the $k!$ denominator.  This problem came up in computing the probability of a draw in a football match with each team's goal scoring modeled as a Poisson process.  Thanks,  John About integer factorization ACPI error when trying to make dual boot with Ubuntu 18.04 and Windows 10 I am trying to install a fresh version of Ubuntu in my computer without touching the windows 10 dual boot! In the Installation Type, the first option seems exactly what i wanted to do.  My question is, is this feature is safe to use? because i don't want to lose any windows files and other NTFS partitions on the hard-disk. Please eliminate my confusion. Note as that i dont need any files or media which are in the ubuntu partition, Thanks. Changing the size of the mouse pointer in Ubuntu MATE 18.04 does not work I have Ubuntu 18.04 with the gnome-desktop  and parallel the Ubuntu MATE desktop installed. While I can easily change the size of the mouse pointer (DMZ-White) in the Gnome3 desktop , this does not work on the MATE desktop. I use for this the dconf-editor.  Maybe someone knows a solution?  Thanks a lot. How to unselect Excel Cell using Keyboard Shortcut? One can select multiple Excel cells (either contiguously or not) using the keyboard shortcut Ctrl+Click.   How do you deselect one or more of these previously-selected cells? When I get a third party app it says it needs to be verified before I can use it but when I go to settings to verify I tap verify and nothing happens. Is there something I can do so I don’t have to constantly reinstall my apps? Enable copy and paste on UITextField without making it editable Galois Group of $\sqrt{2+\sqrt{2}}$ over $\mathbb{Q}$ I mean are we certain that they will be able to provide us a huge improvements (in some tasks) compared to clasical computers? Let  $$0 \rightarrow M \rightarrow N \rightarrow P \rightarrow 0$$  be an exact sequence of $A$-modules, where $A$ is a commutative ring with unity.  Then for each natural number $i$ one can look at the induced maps  $$\mathrm{Sym}^i(N) \rightarrow \mathrm{Sym}^i(P)$$  and   $$\mathrm{Sym}^i(M) \rightarrow \mathrm{Sym}^i(N).$$  The first question is, if they are still surjective, resp. injective, i.e. is $\mathrm{Sym}^i$ an exact functor?  The second question is: what are the kernel, resp. cokernel of these maps? Everything I have read says that you do not need to soak lentils like you would beans.  Unfortunately the last several times I have cooked lentils they have seemed a little chalky.    Should I be soaking my lentils before I cook them?