Python single line if-else via dictionary
Does Python have a ternary conditional operator?
Refresh thumbnails in nautilus How does one refresh thumbnails in nautilus? In my videos folder I have some MKVs and only half of them have the movie border and a excerpt from the movie and the others (also MKVs encoded in the same way) just have the ordinary film icon.  (F5 doesnt do it.) Beryllium Vacuum Sphere Boat/Aircraft Is it possible to make a solid rigid evacuated "balloon" out of Beryllium or other elements or alloys?  The critical buckling pressure at which an evacuated sphere is given as $$ P_1=\frac{2E\cdot\left(h/R\right)^2}{\sqrt{3\left(1-\nu^2\right)}} $$ where $E$ is , $h$ the shell's thickness, $R$ the radius to the midsurface shell, and $\nu$ is .  Of course this is theoretical and experimental and literature values for submersibles hover around 1/4 of the theoretical pressure.  Beryllium has the following properties:   Density=1.85 g/cm$^3$ Young's Modulus=287*10$^9$ Pa Poisson Ratio=0.032   Calculating the upward force, buoyancy at 101.3 kPa atmospheric pressure and Radius of 10m gives 4.24*10$^8$ N. The weight of this sphere with shell thickness 1mm has 2.32*10$^7$ N downward force of Beryllium material, so it will theoretically float at ground level.   Calculating the critical buckling stress of this beryllium sphere is 331.57 kPa, which is 3.27 times the atmospheric pressure of 101.3 kPa, so theoretically it won't buckle. But in experimentation done in earlier experiments as stated before, due to construction/material non-ideal situations, the critical buckling formula predicts about 4 times stronger than actual, so it would need about 400 kPa, not 331 kPa as Beryllium sphere with this specification would hold. Increasing the strength capability also increases weight and therefore lowers it's ability to float, but Beryllium is the closest element with this situation I have calculated that could work if ideal (I have only been using periodic table elements and household materials)  Is it possible with an alloy of elements? Using the equations for buckling and buoyancy, the following is needed. What alloys/materials come to your mind?  Material considerations:   Material with larger Poisson ratio Material with larger Young's Modulus Less dense material Construction (is it possible)   Material considerations affect on lift   Thickness can be larger, increases strength by the squared. But also increases weight. If a material with lower density with similar structural properties as Beryllium is used, it would help. Radius can be lower for same reason, but also lowers buoyancy (volume)   My other designs (don't worry about these just yet, just if you are curious is a vacuum sphere with a pressurized "outer tube" with spokes in tension (carbon fiber nanotubes maybe) to keep the 2 spheres in position. Another is a spherical truss out of carbon fiber nanotubes with a light membrane around. The truss prevents the outer membrane from collapsing due to the atmospheric pressure  The "point" of this if you ask, as to why not use a traditional balloon is it can be used as a boat by filling the sphere with air, and then used as a aircraft at will by evacuating the sphere. An alternative mode of transportation for sea vessels etc. When building console applications that take parameters, you can use the arguments passed to Main(string[] args).   In the past I've simply indexed/looped that array and done a few regular expressions to extract the values. However, when the commands get more complicated, the parsing can get pretty ugly.    So I'm interested in:   Libraries that you use Patterns that you use   Assume the commands always adhere to common standards such as . How can I determine that I am looking at the block I need? Why are trivial edits discouraged? Looking at  privilege, I find this to be a surprising requirement:  Try to make the post substantively better when you edit, not just change a single character. Tiny, trivial edits are discouraged.  What motivated this, or rather, what does this mean exactly? Does that, for example, include removing stuff like &quot;Hi, all&quot;, and &quot;thanks in advance&quot;? [update] I was led to a  talking about this topic, but it has a million Comments, and doesn't really justify the rule (unless it's hidden in those million Comments). However, looking at Jeff's Comments gives me an idea that this was meant as a general guideline, instead of a hard-and-fast rule: If you edit a post, check elsewhere on that post if there are other improvements that can be made. Recovering accidentally deleted files Where are the corrosive weapons at? I'm a Siren and I'm getting almost nothing but Fire elemental guns; about 90% of guns have been fire, most of the rest Explosive and a scare few Shock.  Are the elemental varieties more common at different levels? I've seen zero corrosive/shock guns so far. I'm level 12 at the moment. How do I suppress the whitespace above an equation block at the page top? How do I suppress the whitespace above the equation block at the page top ? It is added to the top margin, and I don't want that to happen. I know that \abovedisplayshortskip controls this for the whole document, but how can I change this for this particular equation block and NOT for any others ? Negative vspace doesn't work.  \documentclass[pdftex,12pt,a4paper,english,dutch,leqno]{article} \usepackage[top=1cm,right=1cm,bottom=1cm,left=1.5cm,noheadfoot]{geometry}         \usepackage{babel} \usepackage{amsmath} \usepackage{amssymb} \usepackage{empheq}  \begin{document}  \abovedisplayskip=6pt \abovedisplayshortskip=3pt % This should NOT be changed \belowdisplayskip=6pt \belowdisplayshortskip=3pt  \begin{equation*} \left.\begin{array}{r} a_{31}'=a_{11}\cdot a_{31}-a_{31}\cdot a_{11}=0\\ a_{32}'=a_{11}\cdot a_{32}-a_{31}\cdot a_{12}\\ a_{33}'=a_{11}\cdot a_{33}-a_{31}\cdot a_{13}\\ a_{34}'=a_{11}\cdot a_{34}-a_{31}\cdot a_{14}\\ b_{3}'=a_{11}\cdot b_{3}-a_{31}\cdot b_{1} \end{array}\!\!\right\} \Longrightarrow\; \begin{matrix*}[l] \text{Pseudo-code :}\\ a_{11}\cdot b_{3}-a_{31}\cdot b_{1}\mapsto b_{3}\text{.}\\ \forall\;i\in\{4,3,2,1\} : a_{11}\cdot a_{3i}-a_{31}\cdot a_{1i}\mapsto a_{3i}\text{.} \end{matrix*} \end{equation*}  \end{document} C# Equivalent of SQL Server DataTypes For the following SQL Server datatypes, what would be the corresponding datatype in C#?  Exact Numerics  bigint numeric bit smallint decimal smallmoney int tinyint money     Approximate Numerics  float real     Date and Time  date datetimeoffset datetime2 smalldatetime datetime time     Character Strings  char varchar text     Unicode Character Strings  nchar nvarchar ntext     Binary Strings  binary varbinary image     Other Data Types  cursor timestamp hierarchyid uniqueidentifier sql_variant xml table   (source: ) I'm teaching my self topology with the aid of a book. I'm trying to prove the following is a topology:     Let X be an infinite set. Show that $\mathscr{T}_2=\{U \subseteq X : U = \emptyset $ or $ X\setminus U $ is countable$ \} $ is a topology.   My book calls this set the ""  Please let me know if my proof is valid.     corollary [A]: The union of countable sets are countable.    proof: I'm going to take as a given that that the union of finite set are finite, and just prove the case of . A set is countable infinite if there is a bijection between the set and the natural numbers. Let $A$ and $B$ be a countable infinite sets. Now let $f$ be the bijection between $A$ and $\mathbb{N}$ and $g$ be $B$'s bijection.  $f:\mathbb{N}  \rightarrow  A$  $g:  \mathbb{N}  \rightarrow B$  There can always exist a bijection $h$ that maps $A \cup B $ to $\mathbb{N}$. To account for non disjoint sets, let $B' = B \setminus A$; (note: $A \cup B = A \cup B'$)  $h:  \mathbb{N}   \rightarrow  A \cup B'$  $ h(x) = \left\{         \begin{array}{ll}             f(\frac{1}{2}x); &amp; \quad x \in 2\mathbb{N} \\             g(\frac{x+1}{2}); &amp; \quad x \in 2\mathbb{N}+1         \end{array}     \right. $   $h^{-1}(x)$ would map $A$ to the even numbers, and $B'$ to the odd numbers.  Therefore, The union of countable sets are countable. (QED)  Now to verify the definition.     (i) X and Ø are elements of $\mathscr{T}$.   Ø is given in the definition of $\mathscr{T}_2$. Also, the empty set is considered finite, with cardinality zero. Thus $X$ is in $\mathscr{T}_1$ because its complement is finite, and finite numbers are countable.      (ii) $\mathscr{T}$ is closed under finite intersections.   Let:$V_k \subseteq X$ be any countable set. (ie: $V_1, V_2...$ are all countable sets)  So Then, $U_k = X \setminus V_k$, would be the subsets of $\mathscr{T}_2$.  $U_k \cap U_j = X \setminus (V_k \cup V_j) $, due to De Morgan's law.   Thus, $U_k \cap U_j \in  \mathscr{T}_2$, since the Union of two countable sets is also countable[A]. And This reasoning can be extended to any finite amount of intersections.       (iii) $\mathscr{T}$ is closed under arbitrary unions.   Let $A=\bigcup_{i \in I} U_i$ be an arbitrary union of sets whose complements are are countable.Then by De Morgan's law, $A=X \setminus (\bigcap_{i \in I}V_i)$, for some countable sets $V_i$. By the definition of intersection, $\bigcap_{i \in I}V_i \subseteq V_i$ for all $i \in I$. Since $V_i$ is countable so is any of its subsets.  Hence the complement of $A$ is countable. Short story with competitors complaining to government about a new very popular synthetic food Why don't the heads of phospholipid bilayers repel hydrophobic molecules? Say that Player X is 2nd in the initiative. 1st is the Black Court vampire that is in a rage and taking a swing at Player X. Player X gets a built in defense [Athletics/Fists + 4dF] but can Player X instead use his action this turn to cast his Rote Evocation Shield?  It is not his turn in the initiative order. A Block is an Action that a Player can take on his turn.   Thematically though, it seems to make sense that the char could cast a Rote Evocation Shield in response to an attack ahead of him in the initiative order. At least thematically in the books. Also, the example in YS252, shows him reacting to an attack by Agatha Hagglethorn by bring up his shield.  I am hoping there is some as yet undiscovered dark corner where this concept is covered or squashed. A  is formed when a raindrop refracts light, but why then does the whole sky not become a huge rainbow when it rains? Would the light not be dispersed into ordinary white light? What causes it to look as if each end is nearly touching the ground? Give an example of a sequence of real numbers with subsequences converging to every real number Sci-fi series: humans are immune to telepathy, become soldiers for an alien group fighting against invertebrate telepaths The series involves two groups of aliens who have been fighting an interstellar war for many years before the first book.  The war is started by a race of jellyfish-like telepaths who have used their powers to control several species which they use as soldiers.  The jellyfish aliens have declared a holy war against all sapient vertebrates.  The only species on their side that aren't being actively controlled through their telepathy are invertebrate species who have joined the holy war.  In this series, humans are immune to telepathy--what's more, a completely unconscious reflex tends to destroy the mind of anything even attempting to affect their minds.  One of the central themes of the series is how well suited humanity is to warfare, and all the sacrifices forced on humanity as they become nothing but soldiers fighting against the jellyfish, losing almost all culture not in some way related to being soldiers, as the other races in their alliance take over the other roles.  Other species I recall include a bird race that is gifted at linguistics but can be sent into shock by even seeing a low quality recording of a human walking around a room.  They just cannot handle the hide or flee reflexes triggered by seeing such an obvious predator.  Another race is a crab like group that is so antisocial they all keep suicide buttons at hand when working with other races, and only work to help the human alliance's side because the jellyfish won't leave them alone.  There is a race that bears a faint resemblance to large rats who were previously the best soldiers on their side, and another renowned for their intellect. lsusb relevant output Bus 001 Device 006: ID 0bda:8812 Realtek Semiconductor Corp. RTL8812AU 802.11a/b/g/n/ac WLAN Adapter  Upon plugging the device it is recognized by lsusb, however when I go to wireless settings no adapter is recognized. The driver is installed (by going to software and updates -> addition drivers and selecting the open source driver). I'm using Linux Mint. My login shell (cat /etc/passwd | grep myUserName) is bash.  After I start my graphical desktop environment and run a terminal emulator from it, I can see that .bash_profile is not sourced (environment vars that are exported in it are unset). But if I log in from a text console (ctrl+alt+F1) or manually run bash -l from the terminal emulator, .bash_profile works fine.  Am I wrong when I think that .bash_profile should be sourced when X starts and all export'ed vars should be available in the terminal, running from X?  P.S. Placing everything in .bashrc and sourcing it from .bash_profile is not good idea (): environment stuff should be sourced only once. Duplicates of duplicates should be remapped I noticed today another example of duplicates of duplicates: that  (A) was closed as a duplicate of  (B), but one day later (B) was closed as duplicate of  (C). Sometimes I need to click many times from one question to another until I get to the master question.  I think that it's better if the question (A) is closed as duplicate of (C), and even if (B) has already (helpful) answers, (B) and (C) could be merged.  Is it possible to remap all duplicates to the master question, just like the tag synonyms? Let $P\in\mathbb{R}[X]$ be a positive polynomial.  I want to show that there exists $A,B\in\mathbb{R}[X]$ so that $P=A^2+B^2$    $\displaystyle P=a\prod_{k=0}^q(x-a_k)\prod_{k=0}^{2p}(x-b_k)=a\prod_{k=0}^q(x-a_k)\prod_{k=0}^p(x^2-2\Re(b_k)+|b_k|^2)$ where $a$ is the leading coefficient, $a_k$ are the real rooks, $b_k$ are the complex roots.  What can i do now ? I know that the identity $(a^2+b^2)(c^2+d^2)=(ac-bd)^2+(ad+bc)^2$ should come in handy, but I can't figure out :  1) How to show that the product real roots is a square  2) How to use the above identity for the complex roots.  If I can solve those two points, then I can solve the problem.