Why color of dress changes when water falls?
Why do wet objects become darker?
Initial connection to SQL Server Connection Is Slow. Why? The difficulty is that it should be cross platform. Windows 2000, XP, Vista, OSX, Linux, other unix variants. I am looking for a snippet of code that can accomplish this for all platforms, and a way to detect the platform.  Now, you should be aware of  that user.home does not work correctly, so please do not provide me of textbook answers, I can find these myself in the manuals. Find PostgreSQL server hostname on which it runs Can't reset WordPress password I haven't logged onto my blog for years, and have, of course, forgotten the password. I click the 'Forgot' button and get a mail with a link, but that mail already says     Sorry, that key does not appear to be valid.   And sends me round the click to reset, receive a mail, click the link again etc. As if the timeout for password resets has been set to 0.5s or something.  This is a shared hosted blog, so I have full access to cPanel and all of the WP files via FTP, if that helps anything. Let $R$ be a commutative Noetherian ring (with unity), and let $I$ be an ideal of $R$ such that $R/I \cong R$. Then is it true that $I=(0)$ ?  I know that a surjective ring endomorphism of a Noetherian ring is also injective, and since there is a natural surjection from $R$ onto $R/I$ we get a surjection from $R$ onto $R$, but the problem is I can not determine the map explicitly and I am not sure about the statement. Please help. Thanks in advance. Is it possible to download using the Windows command line? Without using any non-standard (Windows included) utilities, is it possible to download using the Windows command line?  The preferred version is Windows XP, but it's also interesting to know for newer versions.  To further clarify my question:   It has to be using HTTP The file needs to be saved Standard clean Windows install, no extra tools   So basically, since everybody is screaming , I want simple Wget functionality, without using Wget. Cloning a Non-Standard Svn Repository with Git-Svn I'm relatively new to Git, but I've found it so easy to work with at home that I'd like to use it at work where our projects are stored in Svn repositories. Unfortunately, the repositories are slightly non-standard and I'm having trouble getting them cloned. Sure, they all have trunk, branches/ and tags/, but branches/ and tags/ have subdirectories before hitting the real project directories:  trunk/ branches/maintenance/release1 branches/maintenance/release2 ... branches/development/feature1 branches/development/feature2 ... tags/build/build1 tags/build/build2 ... tags/release/release1 tags/release/release2   After cloning:  $ git svn clone -s --prefix=svn/ https://mydomain.com/svnproject $ git branch -r   development   development@1340   maintenance   maintenance@1340   tags/build   tags/build@1340   tags/release   tags/release@1340   trunk   trunk@1340    I get none of the actual project branches or tags. I actually need to be able to work on the trunk, one maintenance branch and one development branch. I've tried this approach in addition to several hacks at modifying the config, but nothing is working for me.  Is there any way I can get the key components of my non-standard Svn project into a local git repository so that I can easily move between them?  Many thanks.  UPDATE: I should add that I can't do a wholesale switch to Git (yet). There are other team members involved and an international presence. The logistics of the transition are more than I'm willing to undertake until I'm much more comfortable with Git; as I mentioned, I'm still pretty new. I've barely scratched the surface of its capabilities. What size images do I need for common print sizes, such as wallet size, 8x10, and 16x20?  Is there a general formula?  How could that size change if, for example, a 16x20 was printed on canvas rather than photopaper? Asymptotic complexity of .NET collection classes Unable to start Oracle database We have an Oracle database, one data file (users tablespace) of the instance got corrupt and another data file (containing application data) was deleted due to some issue.  The database is in ARCHIVELOG mode, but we neither have data file backup of both data files nor the pertaining archive logs. Hence, I guess we cannot go ahead with the recovery of data files. I am unable to open the database as the data files are not available and face.   ORA-01589: must use RESETLOGS or NORESETLOGS option for database open    I am just able to STARTUP MOUNT the database  I wanted to ask if we can somehow we can open the database by taking both the tablespaces offline after STARTUP MOUNT the database instance. Or if there is any other way I can start the database.   There was a power issue and the  server got abruptly shutdown. When we tried to restart the database and found that we were facing ORA-01589: must use RESETLOGS or NORESETLOGS option for database open. On further analysis we found that 2 of datafiles were creating problem as one got corrupt other deleted as mentioned. As of now if I try to restart the database it says one datafile which belongs to users tablespace need recovery. I wanted to confirm as if we can start the instance by bringing the tablespace offline.  I tried:  SQL&gt; select open_mode from v$database;  OPEN_MODE ---------- MOUNTED  SQL&gt; alter database open resetlogs; alter database open resetlogs * ERROR at line 1: ORA-01194: file 1 needs more recovery to be consistent ORA-01110: data file 1: '/flowsystems/oradata02/flsta02/system01.dbf'   I don't have any archive logs. I'm embarking on a new web map project that seeks to display simple geometries (lines, points, polygons) and rasters/basemaps. Ideally, the map will also allow authorized users to add/remove/edit geometries and their attributes.  What are the available options for the storage of data (e.g. SQL Server Spatial)?  What are the available options for the presentation of data (e.g. ArcGIS Server)?  I'm new to web mapping and am attempting to build a solid understanding of the available options and their pros/cons. I find I have to scroll a lot to move the text of my page compared to Windows where I can choose the speed of the mouse wheel.   Does Ubuntu have a similar utility and if so how can I access it? How to find an end point of an arc given another end point, radius, and arc direction? Given an arbitrary arc, where you know the following values: end point (x1,y1), radius (r) and arc direction (e.g. clockwise or counterclockwise from start to end), how can I calculate the other endpoint of the arc (and I say endpoint because I think of an arc as line segment that is curved, which happens to lie on the circumference of the circle and it has two end points).   Though that's just how I interpret the problem and maybe I'm not thinking about it correctly.  EDIT: Yes, I know the Origin point and the length of the arc. Sorry I forgot to mention. Also, the that circle would be on a 2D Cartesian plain (x and y axis.) Sorry, my math terminology is lacking.   Also, I'm not trying to cheat on homework or anything. This is a legitimate problem for an SVG graph I'm trying to create using JavaScript and I've tried my best but I need help.  Thanks in advance. A ring of a planet has an inner radius of approximately 52,000 km (measured from the center of the planet) and a radial width of 19 km. Use differentials to estimate the area of the ring. (Round your answer to the nearest thousand.)   I hate asking questions where I have nothing to contribute but I have absolutely no Idea on how to approach this question. A step by step solution to this problem which I could apply to similar problems would be greatly appreciated, thanks in advance. What's the use/meaning of the @ character in variable names in C#? I discovered that you can start your variable name with a '@' character in C#.  In my C# project I was using a web service (I added a web reference to my project) that was written in Java. One of the interface objects defined in the WSDL had a member variable with the name "params". Obviously this is a reserved word in C# so you can't have a class with a member variable with the name "params". The proxy object that was generated contained a property that looked like this:  public ArrayList @params {     get { return this.paramsField; }     set { this.paramsField = value; } }   I searched through the VS 2008 c# documentation but couldn't find anything about it. Also searching Google didn't give me any useful answers. So what is the exact meaning or use of the '@' character in a variable/property name? continuity, discontinuity derivative and relation to being derivative but its partials are not continuous is $$f(x) =\begin{cases} x^2\sin(\frac{1}{x}) \mbox{ for } x\neq 0 \\ 0  \mbox{ for } x= 0\end{cases}$$ a continuous function specially at point x=0?  And why being derivable its derivative is not continuous at x=0 since  $$f`(x) =\begin{cases} 2x\sin\frac{1}{x}-\cos\frac{1}{x} \mbox{ for } x\neq 0 \\ 0  \mbox{ for } x= 0\end{cases}$$?  I suspect this as to do with being derivable a function f $\mathbb{R}^n\rightarrow\mathbb{R}^m$ that don't imply its partial derivatives are continuous .this I don't get it so far.however partials derivatives if continuous is derivable.  Can you provide me a more general case than just one variable where f is derivable but its partials are not continuous? Including Interaction Terms in Random Forest Suppose we have a response Y and predictors X1,....,Xn. If we were to try to fit Y via a linear model of X1,....,Xn, and it just so happened that the true relationship between Y and X1,...,Xn wasn't linear, we might be able to fix the model by transforming the X's somehow and then fitting the model. Moreover, if it just so happened that the X1,...,XN didn't affect y independent of the other features, we also might be able to improve the model by including interaction terms, x1*x3 or x1*x4*x7 or something of the like. So in the linear case, interaction terms might bring value by fixing non-linearity or independence violations between the response and the features.  However, Random Forests don't really make these assumptions. Is including interaction terms important when fitting a Random Forest? Or will just including the individual terms and choosing appropriate parameters allow Random Forests to capture these relationships? What is the noun for someone who receives a referral? When a referrer (noun) gives a referral (noun) to another person, what is the term (noun) used for the recipient of the referral? "The referred" may work, but am I missing another term? "Referred" indicates past-tense, but I intend to use the term in future and present tense as well. Which is correct: "he don't" or "he doesn't"? W.K.T, any user(with more than 2k rep) can review 20 suggested edits per day.  Today I saw the newly appointed moderator  reviewed more than 20.    Is it possible for moderators to review more than the daily limited count?  If yes, can any moderators can do it at any time?  I didn't see this before.