What gives things color?
What causes atoms to have their specific colors?
Can I add extension methods to an existing static class? I'm a fan of extension methods in C#, but haven't had any success adding an extension method to a static class, such as Console.  For example, if I want to add an extension to Console, called 'WriteBlueLine', so that I can go:  Console.WriteBlueLine("This text is blue");   I tried this by adding a local, public static method, with Console as a 'this' parameter... but no dice!      public static class Helpers {     public static void WriteBlueLine(this Console c, string text)     {         Console.ForegroundColor = ConsoleColor.Blue;         Console.WriteLine(text);         Console.ResetColor();     } }   This didn't add a 'WriteBlueLine' method to Console... am I doing it wrong? Or asking for the impossible? The legacy tray (see the screenshot below) will be removed in GNOME 3.26. I want to wean myself off it before the change arrives in Ubuntu (17.10 or 18.04).    Can I disable the legacy tray in Ubuntu GNOME 17.04? If every element of set A ia an element of set B then we say that A is subset of B. A is said to be proper subset if A does not equal B.  My question is - whether the symbol we use to show subset is  same as that for proper subset? I have seen that A is subset of A itself is shown by the same symbol as that for the subset while when we write improper subset, we usually write equal to sign with symbol of subset. So, please help me to know this. How to get Text to follow semicircular path, read left to right and oriented counterclockwise I'm using adobe illustrator, and I'm trying to get the text to orient from left to right(counterclockwise) and not upside down but I cannot get it to do that on the path I've created. Im pretty beginner with illustrator, any help would be greatly appreciated. thank you What is the difference between an SLR and a DSLR? What are the differences between SLRs and DSLRs? (I know that DSLRs are Digital SLRs but are there any actual differences?)  Also, what are the advantages/disadvantages of both? Where should the comma be placed in the salutation of a letter? Sometimes I see a comma after the proper name:     Hello Mr. Black,      In order to give you....   But my native language is not English and I think that the comma in this phrase should be placed before the proper name:      Hello, Mr. Black.      In order to give you....   What is the correct punctuation in English? I am interested in finding out how confident my model (say Logistic Regression) is in predicting the label of a new data point. For example, if it is not confident, I better abstain from making a prediction.   Logistic Regression outputs probabilities, which gives you a notion that there is confidence in prediction. But in fact, it is not. $P(y|x)$ being 0.3, doesn't tell me that the model is confident in its prediction or not. All, we can say is that it believes 100% that class A is 0.3 and other class is 0.7.  Can we use confidence intervals of LR as some sort of confidence in prediction? E.g., larger the difference between upper and lower bound for a particular data point, less confident it is, and vice-versa?  If not, how can we build confidence in our prediction? Can anybody guide me to some paper or field of study? SharePoint search not showing any results when searching partial name such as "frank" I have search service application configured.  Suppose my first name is "frankmartin" (no spaces)  When I search "frankmartin" then it displays search results in both "People" and "Site" search. But when I search "frank" it doesn't display any search result. Why is that?  EDIT  I am not using advanced search and have made this search results page using those search web parts which you can add in page to display results. I heard a lot about in-body image stabilization recently and I wonder how this technology works. I don't mean the mechanical part (I understand how the sensor moves along different axes to compensate), but the technique in principle:  When I take my 5D III and a lens like the 70-200 2.8 II IS USM with activated stabilization, the IS will constantly move one glas element within the lens in such a way that it directs the cone of light exactly onto the sensor, so that you can always use the full sensor area.  When the cone of light goes through an unstabilized lens and you need to move the sensor - how can it capture the same amount of light at all? The light enters the lens down a fixed axis right through the center of the lens. When the sensor currently moves down, for example, to compensate for a shake, I can't see how it then is still able to capture the full resolution? When a part of the sensor is below default/calm position, then there must be missing the same part on the opposite site?  There's only one way I could image IBIS to work without resolution reduction: if the sensor area was significantly bigger than the area exposed to light, so that there's still sensor available when it currently moves out of its initial position. But wouldn't this (partly) be the same as digital stabilization because the final image gets calculated from the full sensor area minus the not exposed area?  I really would like to understand this and it would be great if someone could "shed some light on this". I just installed Call of Duty 4 and when I try to run the single player mode nothing happens. I just see a quick flicker on the desktop but the game doesn't launch. When I try to run it again, it gives me this message:      It appears that cod4 did not quit properly the last time it ran. Do you want to run the game in safe mode?    Multiplayer seems to work fine and when I try to switch to single player from the multiplayer menu the same thing happens, it just goes back to my desktop and that message shows up again How to convert a single char into an int What free Remote Desktop (server) solutions are there? I know Ubuntu comes with a "Remote Desktop" option that appears to be a straightforward VNC server, and I'm trying to understand the alternatives. Here are the possibilities I've heard about so far:   VNC  VNC + SSH Tunnelling NX Server, free edition FreeNX NeatX X2Go X11 Forwarding over SSH xrdp    I'm coming at this from a Windows user's perspective: To the best of my experience, RDP (aka Terminal Services) is a reasonably secure (barring mitm/server spoofing), efficient desktop sharing protocol with well-supported clients, that can be exposed to the internet when necessary without major fears of intrusion. To the best of my knowledge straight VNC is none of those things, which is where I get confused - why wouldn't a better desktop sharing technology be developed or used in the open-source world? I know VNC can be wrapped with SSH, but that seems beyond the reach of a casual user. X11 forwarding over SSH may be more or less efficient, I have no idea, but is definitely even more complicated, and doesn't (as far as I know) give you access to already-running stuff (no desktop sharing as such, just remote application running).  So, I'd like any feedback/preferences amongst these or any other "Free" desktop sharing options, using these criteria and/or any others:   Security (esp. for access across internet) Efficiency (bandwidth usage, responsiveness, etc) Free-ness, as in Speech (not sure where RDP or FreeNX lie for this) Free-ness, as in Beer (are there any commercial solutions with usable dependable free offerings?) Ease of use (server and client side) Cross-OS Client availability Cross-OS Server availability Support for independent sessions and shared (and/or "Console") sessions Ongoing support/maintenance/development   Thanks! I have a Student object and have a pick list field  "Student Status" in this object. Status can be Full-Time OR Part Time. Now my requirement is i want this student status list, Part-Time or Full-Time in apex controller. how can i do this?  If i get a student record it will only give me that particular student status Full-Time or Part-Time. But i need all options that are available in student status field.  Please help me If $R_{1}$ and $R_{2}$ are relations on a set S with $R_{1};R_{2}=R_{2};R_{1}$. Then $R_{1}$ and $R_{2}$ are bijective maps For the surjectivity part, I showed that if $(a,b)\in I$ then $(a,c)\in R_{1}$ and $(c,b)\in R_{1}$ and $(a,c)\in R_{2}$ and $(c,b)\in R_{2}$ for some $c\in S$. Now for arbituary $(x,y)\in R_{1}$ we have $(x,z)\in I$ which implies that $(y,z)\in R_{2}$. But also $(y,z)\in R_{1}$, so $R_{1}$ is surjective. Similar argument for $R_{2}$  And for Injectivity, I've tried to show that if $aR_{1};R_{2}c$ and $bR_{2};R_{1}c$, then $a=b$ but I am not entirely sure what $a=b$ means in this context. Do I have to show that there is an equivalence relation containing (a,b)?  edit: $R_{1};R_{2}$ is a composition of two relations and $I=R_{1};R_{2}$ I have 8 individual SQL Server 2008 R2 machines, each hosting 1 database. Each database has an identical table structure and schema, and entirely unique data.  I would like to establish a reporting server (may be 2008 or 2012), that consolidates the rows  from selected tables across the 8 source servers into a single instance of those tables on the reporting server. This is one-way replication (no changes will be made to the reporting server). I will need to replicate changes from the source databases with relatively low latency (say 20-30 seconds).  Furthermore, I'd like to find methods to achieve this with as little impact to the source servers as is practical.  3rd-party agents, triggers, or schema mods to those servers are difficult in my environment.  My questions:   What are promising architectures and technologies for  achieving this goal?  I've looked at SQL Server Merge Replication, but I am concerned about latency. Is this an appropriate technology for this goal? Are there many-to-one architectures for transactional replication?   Should I be looking at 1-to-1 replication into 8 databases on my reporting server, followed by some custom merge function (a 2-step replication)?   Thanks, John How do I migrate my Keychain's "Local Items" to a new Mac? After preforming a Mavericks-Mavericks migration using Migration Assistant, I have a "Local Items" Keychain on my new machine in which many (perhaps most) items are out of date (using old passwords), and some are missing altogether. While I have access to a copy of the entire contents of the ~/Library/Keychains/ directory from my old machine, which presumably contains all the information I'm missing, I see no way of importing that information into my new machine.  How can I import the "Local Items" from my old Keychain into the Keychain on my new machine? How do I force Python's print function to output to the screen? This problem is from a practice exam I was working on.     What is the cardinality of the quotient $\mathbb{Z}[x]/(x^2-3,2x+4)$ ?   Thoughts. If I find a ring that is easier to handle then this then I can go from there. So I think this is isomorphic to $\mathbb{Z}_2[x]/(x^2-3,x+2)$. And then I am stuck.  Am I correct so far? What should I be looking to do from here?  Thanks for your time and your answers. How do I know whether to use the definite (the) or indefinite (a, an) article, and when to omit it altogether? Why do the measurements of this object seem erroneous?