Parallel wget in Bash
Multiple simultaneous downloads using Wget?
Force as gradient of scalar potential energy My text book reads      If a particle is acted upon by the forces which are conservative; that is, if the forces are derivable from a scalar potential energy function in manner $ F=-\nabla V $.   I was just wondering what may be the criteria for force to be expressed as negative gradient of scalar potential energy and HOW DO WE PROVE IT? How can I release and renew my DHCP lease from Terminal? From the Terminal, how can I release and renew my DHCP lease?  Currently, I'm doing the following for the wireless interface, but I'm wondering if there's a better way:  sudo ifconfig en1 down sudo ifconfig en1 up   For the wired interface, replace en1 with en0. The staircase paradox, or why $\pi\ne4$ What is wrong with this proof?    Is $\pi=4?$ We want to have a plain empty sandbox - one without any configuration metadata or data from Production.  Is it possible to have such a sandbox?  Please advise. Is there a keyboard command for 'show desktop'? Like Windows, I want to hit Super+D to jump to the desktop or minimize all windows. I don't see command like that in Keyboard Shortcuts. Any idea? How to Deserialize XML document Destroying a Planewalker before its ability is used Say my opponent plays a planeswalker during their first main phase.  I have a  or some other effect that will kill it after it is already in play, but before they use any of its abilities.  I could respond to them using a +1 ability, but I want to kill it before that effect goes on the stack.  In most casual situations, it would basically come down to whether I say "Hero's Downfall" first, or they say "+1" first.  But I can't imagine that's how it's supposed to work.  Is there a time between when the planeswalker hits the battlefield and when they activate its abilities that they must let me respond? It seems to me that situations like this arise frequently, and they are resolved simply by who speaks up first, which is horrible for such a rules-oriented game. Does flying to Panama from the US reset the ESTA time counter? $S := \{x \in \Bbb R^3: ||x||_2 = 1 \}$ and $T: S^2 \to \Bbb R$ is a continuous function. Is $T$ injective? $S := \{x \in \Bbb R^3: ||x||_2 = 1 \} \subset (\Bbb R^3, || \cdot ||_2 )$ and $T:S^2 \to (\Bbb R, |\cdot |)$ is  a continuous function.  I've already shown that $$T_{\mathrm{max}} := \mathrm{sup}\{ T(x) : x \in S^2\}  \: \: \mathrm{ and }\: \: T_{\mathrm{min}}:= \mathrm{inf}\{ T(x) : x \in S^2\}$$ are reached by $T$ with the argument that $S^2$ is closed and bounded and therefore after the Heine-Borel-Theorem compact, and therefore since T is continuous it assumes its max and min in $S^2$.   Now i have answer the following:     1) Is there a point $x_0 \in S^2$ with $T(x_0)=T(-x_0)$ ?      2) Is there a value $T \in(T_{\mathrm{min}}, T_{\mathrm{max}})$ which is only assumed at exactly one point of $S^2$ ?   I wanted to show that $T$ is injective to get that 1) is false and 2) is true but i didn't get anywhere. Any ideas? Thanks in advance! What is the proper use of [square brackets] in quotes? Find all natural numbers $n$ such that ${(n+1)}^{1/2}-{(n-1)}^{1/2}$ is rational I am using the  for GNOME Shell, similar to the old Maximus extension for GNOME 2 / Unity. When I maximise a window, the title and menu bars are hidden.  But I don't want the minimise, maximise or close buttons to appear in the Activity Bar. , so I have been able to remove the minimise and maximise buttons by disabling them in Tweak Tool.  How do I similarly disable/remove the close (X) button?  (I guess this is the opposite of ) 80's/90's movie: man and woman driving through a red desert planet How to understand linux versioning I need to understand the Linux versioning system and distribution concepts. what are public, stable or final terms for versions? I'm trying to update an existing Subscriber in the All Subscriber Table through the API; i've set up the AppId in the App Center and have connected and created Subscribers, but i'm still having issues updating.  What call do I need to be making to do this? These are the ones i've been trying. Is there a term for someone who "can see multiple perspectives"? A colleague of mine is trying to describe herself as "capable of seeing a situation from multiple perspectives" or "able to look at the big picture from various viewpoints". I feel like there must be a better way to get this point across.  Is there a more concise way to describe this characteristic? Closed form for the sequence defined by $a_0=1$ and $a_{n+1} = a_n + a_n^{-1}$ Find when three numbers have the same remainder when divided by the same number If three numbers 112, 232, and 400 are each divided by the number D, each of their quotients will have the same remainder R. Find R where R>1  How should I approach this? Strange Recurrence: What is it asymptotic to? So I have the following recurrence relation for the growth rate of an algorithm:  $T(n)$ = time taken by algorithm to solve problem of size n:  $$T(n) = T(n-1) + T(\lceil(n/2)\rceil)$$  Clearly this does not obey any polynomial law but now my question is what does it obey?  I merely want an asymptotic equivalence.  My guess is subexponential since this is faster than polynomial but clearly slower than any exponential form.  What though is the question.... What is the optimal path between $2$ fixed points around an invisible obstructing wall?