Need help: 2013 AMC 10 B question #25
System of congruences with variable
My processor is using a big part of my RAM memory as cache and I want to clean it up because of that; will it prejudice something? .NET create scheduled task on server fails with E_ACCESSDENIED I have an ASP.NET website (in C#) that takes in user data and then attempts to create a windows scheduled task.  Of course, this works great on the DEV machine, but fails to run on the server.  I'm trying to figure out what permission(s) are required on the ASPNET user (or anonymous web user) to create tasks.  The error is:  Access is denied. (Exception from HRESULT: 0x80070005 (E_ACCESSDENIED))  Stacktrace:      at MyScheduler.NewWorkItem(String TaskName, Guid&amp; rclsid, Guid&amp; riid, Object&amp; obj)      at MyScheduler.CreateTask(String name)   I've done some searching, and the suggested resolution is to use the web.config 'impersonate' flag to force the application to run as a user with sufficient permissions, as opposed to the ASPNET account which may not have those permissions.  Example:  &lt;system.web&gt;     &lt;identity impersonate="true" /&gt; &lt;/system.web&gt;    Unfortunately, this does not seem to resolve the issue.  From the documentation I read, this should run as the anonymous web user, but it seems that user does not have enough permissions.  I altered the setting to specify a specific domain user that happens to be an administrator on the machine.  Example:  &lt;system.web&gt;     &lt;identity impersonate="true" userName="WindowsDomain\YourUserName" password="YourPassword" /&gt; &lt;/system.web&gt;    Doing this allowed the application to successfully create the Windows Scheduled Task.  So, obviously, with the correct set of Windows 2003 permissions I can get the app to perform as it does in the development environment.  However, I'm not about to place the network or machine administrator account's user credentials in plain text on a Web.config file.  Does anybody happen to know what permissions exactly need to be set in order to get the ASPNET account to behave as desired?  EDIT:  The Win32 API is being used to create scheduled tasks. I've purchased a Canon EF 50mm f/1.8 II. But I'm really disappointed in the results, especially when using it for night photography. :(  In my night shots a lot of lens flare appears in my photos. I've tried to change the angle and position of the camera to no avail. Also I cannot do any night photo without directing my camera to direct light like in street photography!  This photo was taken with my Canon 650D and 50mm 1.8 Lens in a long exposure night shot, and as you notice there is a bunch of lens flare in it. Some people suggested I remove the UV filter. This decreased the lens flare a little but there is still some flare in the photo .    I want to know if there is a problem with the lens? Or is this normal for a $100 lens? Does anyone else have a similar experience with this lens? Photoshop using Marque Tool > Path > Circular But Not a perfect shape? Please consider this image below :   This is happened when I have a circular shape (marquee tool selection). THen after that I converted to Work Path (by right click of that selection). And I add 2.0 as its Tolerance Pixel.   After applying it. The shape become not perfect, could you see the difference? I make it with a black background so everyone could see it from the image no.2.  I realized this is a problem, because If i use that path for placing a text. the text wont follow the correct path as circular (selection), instead ... the shape a bit changed (i think it's ugly shape :: see the detail of the arrow).  How to solve this case ? I'm using Photoshop CS3. New profile pages are out - bugs and feedback master list As a moderator, how do I handle a potentially inappropriate profile picture? $n!+1$ being a perfect square One observes that  \begin{equation*} 4!+1 =25=5^{2},~5!+1=121=11^{2}  \end{equation*} is a perfect square. Similarly for $n=7$ also we see that $n!+1$ is a perfect square. So one can ask the truth of this question:   Is $n!+1$ a perfect square for infinitely many $n$? If yes, then how to prove. Simulating group_concat MySQL function in Microsoft SQL Server 2005? I'm trying to migrate a MySQL-based app over to Microsoft SQL Server 2005 (not by choice, but that's life).  In the original app, we used almost entirely ANSI-SQL compliant statements, with one significant exception -- we used MySQL's group_concat function fairly frequently.  group_concat, by the way, does this: given a table of, say, employee names and projects...  SELECT empName, projID FROM project_members;   returns:  ANDY   |  A100 ANDY   |  B391 ANDY   |  X010 TOM    |  A100 TOM    |  A510   ... and here's what you get with group_concat:  SELECT      empName, group_concat(projID SEPARATOR ' / ')  FROM      project_members  GROUP BY      empName;   returns:  ANDY   |  A100 / B391 / X010 TOM    |  A100 / A510   So what I'd like to know is: Is it possible to write, say, a user-defined function in SQL Server which emulates the functionality of group_concat?   I have almost no experience using UDFs, stored procedures, or anything like that, just straight-up SQL, so please err on the side of too much explanation :) How to tell M2Eclipse to install jar file as a maven dependency What is the purpose of /home on a Mac? On Linux, (which I am used to), /home is the place where home folders live.  On a Mac, home is some kind of crazy mutant:  $ mount /dev/disk1 on / (hfs, local, journaled) devfs on /dev (devfs, local, nobrowse) map -hosts on /net (autofs, nosuid, automounted, nobrowse) map auto_home on /home (autofs, automounted, nobrowse)   Other than to be non-conformist, is there some purpose to this auto_home mount point?  Considering how it mucks up things that come right out of the box, there must be some wonderful thing that it accomplishes, but I can't figure out what that would be..... Cant install via Ubuntu Software- "apt transaction returned result exit-failed" I'm using 17.04 ( Clean Install ), and as far as I remember, every try to install any sofware- it fails with that error code.  I tried sudo apt-get update &amp;&amp; apt-get upgrade and problem persists.  any idea why?   edit: Using software Updater gave this result :   edit : output of update  guy@LG-LAPTOP:~$ sudo apt-get update &amp;&amp; apt-get upgrade [sudo] password for guy:  Ign:1 http://il.archive.ubuntu.com/ubuntu zesty InRelease Ign:2 http://il.archive.ubuntu.com/ubuntu zesty-updates InRelease               Ign:3 http://il.archive.ubuntu.com/ubuntu zesty-backports InRelease             Err:4 http://il.archive.ubuntu.com/ubuntu zesty Release                           503  Service Unavailable Get:5 http://security.ubuntu.com/ubuntu zesty-security InRelease [89.2 kB]      Err:6 http://il.archive.ubuntu.com/ubuntu zesty-updates Release                   503  Service Unavailable Get:7 http://archive.canonical.com/ubuntu zesty InRelease [10.2 kB]             Err:8 http://il.archive.ubuntu.com/ubuntu zesty-backports Release                 503  Service Unavailable Get:9 http://archive.canonical.com/ubuntu zesty/partner Sources [1,416 B]       Get:10 http://archive.canonical.com/ubuntu zesty/partner amd64 Packages [1,616 B] Get:11 http://archive.canonical.com/ubuntu zesty/partner i386 Packages [1,612 B] Get:12 http://archive.canonical.com/ubuntu zesty/partner Translation-en [708 B] Get:13 http://security.ubuntu.com/ubuntu zesty-security/main amd64 DEP-11 Metadata [11.7 kB] Get:14 http://security.ubuntu.com/ubuntu zesty-security/main DEP-11 64x64 Icons [9,219 B] Get:15 http://security.ubuntu.com/ubuntu zesty-security/universe amd64 DEP-11 Metadata [14.4 kB] Get:16 http://security.ubuntu.com/ubuntu zesty-security/universe DEP-11 64x64 Icons [31.0 kB] Reading package lists... Done                                          E: The repository 'http://il.archive.ubuntu.com/ubuntu zesty Release' does no longer have a Release file. N: Updating from such a repository can't be done securely, and is therefore disabled by default. N: See apt-secure(8) manpage for repository creation and user configuration details. E: The repository 'http://il.archive.ubuntu.com/ubuntu zesty-updates Release' does no longer have a Release file. N: Updating from such a repository can't be done securely, and is therefore disabled by default. N: See apt-secure(8) manpage for repository creation and user configuration details. E: The repository 'http://il.archive.ubuntu.com/ubuntu zesty-backports Release' does no longer have a Release file. N: Updating from such a repository can't be done securely, and is therefore disabled by default. N: See apt-secure(8) manpage for repository creation and user configuration details. guy@LG-LAPTOP:~$    output of apt get  guy@LG-LAPTOP:~$ sudo apt-get install putty Reading package lists... Done Building dependency tree        Reading state information... Done The following additional packages will be installed:   putty-tools Suggested packages:   putty-doc The following NEW packages will be installed:   putty putty-tools 0 upgraded, 2 newly installed, 0 to remove and 0 not upgraded. Need to get 661 kB of archives. After this operation, 2,713 kB of additional disk space will be used. Do you want to continue? [Y/n]  Err:1 http://il.archive.ubuntu.com/ubuntu zesty/universe amd64 putty-tools amd64 0.67-3   503  Service Unavailable Err:2 http://il.archive.ubuntu.com/ubuntu zesty/universe amd64 putty amd64 0.67-3   503  Service Unavailable E: Failed to fetch http://il.archive.ubuntu.com/ubuntu/pool/universe/p/putty/putty-tools_0.67-3_amd64.deb  503  Service Unavailable E: Failed to fetch http://il.archive.ubuntu.com/ubuntu/pool/universe/p/putty/putty_0.67-3_amd64.deb  503  Service Unavailable E: Unable to fetch some archives, maybe run apt-get update or try with --fix-missing? guy@LG-LAPTOP:~$ How can I set up Samba shares to only be accessed by certain users? I have a RAID10 array mounted on Ubuntu Server 12.04. I have created a few folders within the mount point and want the following functionality.  There will be 4 users, 3 of them are windows users: 'one' 'two' &amp; 'three'. 'four' is a media streamer that only needs to access the MEDIA share. One Two and Three need to have full access to the media share and their own personal shares (for documents) which no other users but them can access.  Currently, User Four works perfectly (Has full access to the MEDIA folder and can't access folders owned by other users). The problem is, when logged in as the other user, I can't access either share; (tried using valid users =  and using chmod to add permissions to no avail).  TL;DR: I need to know how to configure Samba properly to restrict access to certain shares for certain users and allow all of them to access one communal folder (all files on a RAID10 mount). I want to mount the device /dev/sda3 to the directory /foo/bar/baz. After mounting the directory should have the uid of user johndoe. So I did:  sudo -u johndoe mkdir /foo/bar/baz stat -c %U /foo/bar/baz johndoe   and added the following line to my /etc/fstab:  /dev/sda3 /foo/bar/baz ext4 noexec,noatime,auto,owner,nodev,nosuid,user 0 1   When I do now sudo -u johndoe mount /dev/sda3 the command stat -c %U /foo/bar/baz results in root rather than johndoe. What is the best way to mount this ext4-filesystem with uid johndoe set? What is the use of the Dot Product of two vectors? Introductory Calculus textbook for physics? Taylor expansion for $\arcsin^2{x}$ I stumbled upon this particular expansion that was included in  post.    $$ \displaystyle \arcsin^{2}(x) = \frac{1}{2} \sum_{n=1}^{\infty} \frac{1}{n^{2} \binom{2n}{n}} (2x)^{2n}$$    This caught my eye because I remember trying to derive a Taylor series for $\arcsin^{2}(x)$ a while ago without much success.  Can anyone prove this or point me to a material that would show a proof of this identity?  EDIT :  Feel free to use any mathematical apparatus at hand. I'm not interested in a proof fit for a certain level, nor am I looking for utmost elegance (though that would be lovely). What is the 'Badlock Bug'? A user on the Ask Ubuntu General Room posted a link to . After some googling around, all I can find is that it is a mysterious security bug, that uses the same website template as Heartbleed.  I manage Linux Servers, a mysterious security bug does not sit well with me. What exactly is it, and how can I protect my servers from it? Debate, Bare Plurals, and Mass Nouns What does "proverbial" mean? Does the sign of scores or of loadings in PCA or FA have a meaning? May I reverse the sign? I performed principal component analysis (PCA) with R using two different functions (prcomp and princomp) and observed that the PCA scores differed in sign. How can it be?  Consider this:  set.seed(999) prcomp(data.frame(1:10,rnorm(10)))$x              PC1        PC2  [1,] -4.508620 -0.2567655  [2,] -3.373772 -1.1369417  [3,] -2.679669  1.0903445  [4,] -1.615837  0.7108631  [5,] -0.548879  0.3093389  [6,]  0.481756  0.1639112  [7,]  1.656178 -0.9952875  [8,]  2.560345 -0.2490548  [9,]  3.508442  0.1874520 [10,]  4.520055  0.1761397  set.seed(999) princomp(data.frame(1:10,rnorm(10)))$scores          Comp.1     Comp.2  [1,]  4.508620  0.2567655  [2,]  3.373772  1.1369417  [3,]  2.679669 -1.0903445  [4,]  1.615837 -0.7108631  [5,]  0.548879 -0.3093389  [6,] -0.481756 -0.1639112  [7,] -1.656178  0.9952875  [8,] -2.560345  0.2490548  [9,] -3.508442 -0.1874520 [10,] -4.520055 -0.1761397   Why do the signs (+/-) differ for the two analyses? If I was then using principal components PC1 and PC2 as predictors in a regression, i.e. lm(y ~ PC1 + PC2), this would completely change my understanding of the effect of the two variables on y depending on which method I used! How could I then say that PC1 has e.g. a positive effect on y and PC2 has e.g. a negative effect on y?    In addition: If the sign of PCA components is meaningless, is this true for factor analysis (FA) as well? Is it acceptable to flip (reverse) the sign of individual PCA/FA component scores (or of loadings, as a column of loading matrix)?