I have a social network, where I can place comments on posts. I havce implemented this using a ReactionController that handles API calls for a post that has an event that indicates that the API call finished.  My code goes like this (in my "timeline" controller, when the UI asks me to place a reaction):  public void PlaceReaction(string reaction) {     var reactionController = new ReactionController(post);     reactionController.DishUpdatedEvent += (updatedPost) =&gt; {         // Notify the UI         UIThreadDispatcher.Invoke(() =&gt; SinglePostUpdatedEvent?.Invoke(updatedPost));     };      reactionController.PlaceReaction(reaction); }   and in my ReactionController:  // Saved to API UIThreadDispatcher.Invoke(() =&gt; PostUpdatedEvent?.Invoke(_post));   I am afraid my liberal use of events may cause the ReactionController to remain in memory, but I only want it to stay in memory for the duration of the call, until the event is fired. Will this act like I want it to or do I have a memory leak?
If I have the following code:  MyClass pClass = new MyClass(); pClass.MyEvent += MyFunction; pClass = null;   Will pClass be garbage collected? Or will it hang around still firing its events whenever they occur? Will I need to do the following in order to allow garbage collection?  MyClass pClass = new MyClass(); pClass.MyEvent += MyFunction; pClass.MyEvent -= MyFunction; pClass = null;
Is it appropriate to buy a "thank you" gift for a PhD supervisor? How to apply a bevel modifier, so that it affects only specific edges? Shower at Heathrow during layover in Terminal 5 Reading the  questions here, I am not too hopeful, but this is the perfect site to find the answer if it does exist:  Facts:   I arrive at T5 (British Airways) at 08:30, depart at 11:40 from T5 (British Airways) to another country. No time once I reach final destination to shower, Leave straight from work to catch the first leg. US citizen + passport, only final destination visa (currently)   Desire:  I want to shower - 10 mins is plenty.  Assume money is no object (pay for lounge access, cabs etc), but I'd rather not buy full ticket if I can avoid it.  P.S. It's a wedding, so I REALLY want to shower before haha.  EDIT: My plan so far (which doesn't work because it's after Security):   Travel from  Use    UPDATE:  I followed G &amp; Doc's advice and walked over to the Sofitel Hotel (Immigration + walk ~20-25 min total) showered there for £25 and walked back through Security with plenty of time to spare.  Thank you all for your help! Why does the logo not show up when signing up for a site and confirming the account? I wanted to apply texture on some house following an tutorial, I'm sure I did all what was needed but still don't see the texture.  Here's a screenshot: How can I install a package without installing some dependencies? I'm trying to install the package LaTeXila, and the output looks like this:  $ sudo apt-get install latexila --no-install-recommends Reading package lists... Done Building dependency tree        Reading state information... Done The following extra packages will be installed:   latexila-data latexmk luatex tex-common texlive-base texlive-binaries   texlive-common texlive-doc-base texlive-latex-base Suggested packages:   rubber texlive-latex-extra debhelper Recommended packages:   texlive texlive-latex-recommended texlive-luatex lmodern   texlive-latex-base-doc The following NEW packages will be installed:   latexila latexila-data latexmk luatex tex-common texlive-base   texlive-binaries texlive-common texlive-doc-base texlive-latex-base 0 upgraded, 10 newly installed, 0 to remove and 0 not upgraded. Need to get 29.3 MB of archives. After this operation, 74.5 MB of additional disk space will be used. Do you want to continue [Y/n]?   I don't want to install the texlive packages. I've installed texlive manually from . Any suggestions? Is there a term for when just by saying that something is broken and showing it to someone fixes the issue? This seems to be a common enough occurrence that it would merit its own phrase. I imagine it might be some sort of subset of Murphy's Law. But it's specific enough that Murphy's Law doesn't quite address it.  Do you know when you are banging your head against a wall for hours trying to fix something? And then when you finally give up and try to get someone else to come fix it (or even just look at it to see that it's broken), it's working perfectly as if nothing had ever happened? And at this point, you're just trying to convince the other person that it was broken in the first place.  It'd at least take some of the frustration out of the experience if you could both just laugh about &lt;insert the phrase for it here&gt;. But as it is now, I basically have to go through the whole paragraph above to say it, and at that point the joke is kind of lost. Interpretation of Shapiro-Wilk test I'm pretty new to statistics and I need your help. I have a small sample, as follows:    H4U   0.269   0.357   0.2   0.221   0.275   0.277   0.253   0.127   0.246   I ran the Shapiro-Wilk test using R:    shapiro.test(precisionH4U$H4U)   and I got the following result:   W = 0.9502, p-value = 0.6921   Now, if I assume the significance level at 0.05 than the p-value is larger then alpha (0.6921 > 0.05) and I cannot reject the null hypothesis about the normal distribution, but does it allow me to say that the sample has a normal distribution?  Thanks! Which facility upgrade unlocks maneuver nodes in KSP Which  unlocks  in career mode in KSP?  The  hints that maneuver nodes are now unlocked with a facility upgrade:     Are there any perks for upgrading?      The building in question   will upgrade visually, both from the outside and the inside. More   gameplay mechanics will be also be unlocked as the player progresses   through the different building tiers. For example, allowing EVAs in   space or being able to use maneuver nodes in the map view. What are the different ways that a message can be displayed to a bash shell after a user logs in? I have a CentOS 5.7 VPS using bash as its shell that displays a branded greeting immediately after logging in via SSH. I've been trying to modify it, but can't seem to find where it is in the usual places. So far I've looked in the motd file and checked sshd_config for banner file settings. A banner file is not set.  Where else can I look for where the login message might be? Display Animated GIF Using ArcPy to get all database names within server? I am trying to populate a folder with ArcSDE database connection files for all the databases within a server instance.  I need to be able to do this for several of our servers.  Although I know within SQL Server how to get a list of DB names from the sys.databases table, using the arcpy function CreateDatabaseConnection I cannot specify "sys" or "master" to make the connection.  Therefore, I need to know the name of a database currently in the server.  I am not sure how to make the check without hard-coding a name.  import arcpy arcpy.env.overwriteOutput = True  #Input the location where the database connection files will be stored connectionLocation = "F:/FolderName"  #Get the list of servers arcpy.CreateDatabaseConnection_management(out_folder_path= arcpy.env.scratchFolder,out_name= "GIS_USERCONFIG" ,database_platform="SQL_SERVER",\                                           instance = "XXXXXXX" ,account_authentication="DATABASE_AUTH",username="user",password="password",\                                           save_user_pass="SAVE_USERNAME",database= "GIS_USERCONFIG",schema="#",version_type="TRANSACTIONAL",version="dbo.DEFAULT",date="#") sdeConn = arcpy.ArcSDESQLExecute(arcpy.env.scratchFolder + "/GIS_USERCONFIG.sde") serverListSQL = sdeConn.execute("Select name from userservers") serverList = [] for i in range(0,len(serverListSQL)):     serverList.append(serverListSQL[i][0])  #Make a folder for each server instance and build the connection files for all DBs in the server instance for server in serverList:     folder = connectionLocation + "/" + server     if arcpy.Exists(folder):         print server + " folder already created"     else:         try:             arcpy.CreateFolder_management(connectionLocation, server)             print "Created Folder " + server         except:             print "failed to create folder " + server      #     arcpy.CreateDatabaseConnection_management(out_folder_path= arcpy.env.scratchFolder,out_name= server ,database_platform="SQL_SERVER",\                                           instance = server ,account_authentication="OPERATING_SYSTEM_AUTH",\                                           database= "master",schema="#",version_type="TRANSACTIONAL",version="dbo.DEFAULT",date="#")     sdeConn = arcpy.ArcSDESQLExecute(arcpy.env.scratchFolder + "/" + server + ".sde")     dbListSQL = sdeConn.execute("Select name from sys.databases")     dbList = []     for i in range(0,len(serverListSQL)):         dbList.append(dbListSQL[i][0])     for db in dbList:         arcpy.CreateDatabaseConnection_management(out_folder_path= folder ,out_name= db,database_platform="SQL_SERVER",\                                           instance = server ,account_authentication="OPERATING_SYSTEM_AUTH",\                                           database= db,schema="#",version_type="TRANSACTIONAL",version="dbo.DEFAULT",date="#")   Basically my issue is with the 2nd call for the function "CreateDatabaseConnection_management" since it needs a database that exists in the database (and I could not use "master or sys").  If you open this as a tool in arcmap, the input is a drop-down box that populates choices based on the databases in the chosen server instance.  Is there a way to do this in the code? I develop an application in which i constantly get samples of heart pulse.  I defined an interval of t seconds.  In each t seconds I have n samples.  In every interval, I want to calculate the tendency of those n samples. For example, lets say I have n = 5, and I have samples with values {70, 88, 95, 103, 115}. I want to recognize I have a growth in the heart pulse, and I want to have some measure for the rate of grows/decrease/almost no change.  I thought on two approaches for solving this problem.   I calculate the linear approximation for the n samples using linear regression by applying least squares implemented by the normal equations. (I treat each sample as two coordinates vector with x coordinate as time and y coordinate as heart pulse). I get from the normal equations a linear function of the form y = mx+b and my measure for the tendency is the slope, i.e. the m value. The second approach is to calculate the correlation (pearson's correlation) between vector x and vector y when x is the time and y is the heart pulse.   I'm asking which approach do you think is better for my problem (determining the tendency of heart pulses). Or, do you have a better algorithm for solving this problem? How do I create RAW TCP/IP packets in C++? I'm a beginning C++ programmer / network admin, but I figure I can learn how to do this if someone points me in the right direction. Most of the tutorials are demonstrated using old code that no longer works for some reason.   Since I'm on Linux, all I need is an explanation on how to write raw Berkeley sockets. Can someone give me a quick run down? Question about Conditional Expectation How can I prove that $n^7 - n$ is divisible by $42$ for any integer $n$? I can see that this works for any integer $n$, but I can't figure out why this works, or why the number $42$ has this property. I am trying to show that: \begin{equation} \frac{n}{\phi(n)} = \sum_{d \mid n} \frac{\mu^2(d)}{\phi(d)} \end{equation} where $\phi(n)$ is  and $\mu$ is the .  The identity clearly holds for $n=1$, so if we write $n=p_1^{a_1} \cdots p_k^{a_k}$ for the prime decomposition of $n$, the left-hand side becomes: \begin{eqnarray*} \frac{n}{\phi(n)} &amp; = &amp; \frac{p_1^{a_1} \cdots p_k^{a_k}}{\phi(p_1^{a_1}) \cdots \phi(p_k^{a_k})} \\ &amp; = &amp; \frac{p_1^{a_1} \cdots p_k^{a_k}}{(p_1^{a_1-1})(p_1-1) \cdots (p_k^{a_k})(p_k-1)} \\ &amp; = &amp; \frac{p_1 \cdots p_k}{(p_1-1)\cdots (p_k-1)} \end{eqnarray*}   Whereas the right-hand side becomes:  \begin{eqnarray*} \sum_{d \mid n} \frac{\mu^2(d)}{\phi(d)} &amp; = &amp; \sum_{\substack{d \mid n \\ p^2 \nmid d}} \frac{1}{\phi(d)} \\ &amp; = &amp; 1 + \frac{1}{\phi(p_1)} + \dots + \frac{1}{\phi(p_k)} + \frac{1}{\phi(p_1 p_2)} + \dots + \frac{1}{\phi(p_{k-1}p_k)} \\ &amp; + &amp; \dots + \frac{1}{\phi(p_1 \cdots p_k)} \\ &amp; = &amp; 1 + \frac{1}{p_1 - 1} + \dots + \frac{1}{p_k - 1} + \frac{1}{(p_1 - 1)(p_2 - 1)} + \dots + \frac{1}{(p_{k-1}-1)(p_k-1)} \\ &amp; + &amp; \dots + \frac{1}{(p_1 - 1) \cdots (p_k - 1)} \end{eqnarray*}  I am unsure of how to proceed from this point however. Any help would be much appreciated. I have built a peak detector circuit using op-amps/comparators to amplify the signal from an electret microphone, hold the peak signal and create a sharp logic edge when a peak is detected to be sent to a microcontroller.  I have built the circuit as follows setting up OA1 as a non inverting amplifier with a gain of 1000, but the voltage out from the OA1 remains fixed at about 4.5V no matter how much noise I make into the microphone. The comparator part of the circuit is outputting approximately 2V low and 5V high depending on how I set the potentiometer. All the components appear to be working.         &ndash; Schematic created using How do I copy to the clipboard in JavaScript? What is the best way to copy text to the clipboard (multi-browser)? I have tried: function copyToClipboard(text) {     if (window.clipboardData) { // Internet Explorer         window.clipboardData.setData(&quot;Text&quot;, text);     } else {         unsafeWindow.netscape.security.PrivilegeManager.enablePrivilege(&quot;UniversalXPConnect&quot;);         const clipboardHelper = Components.classes[&quot;@mozilla.org/widget/clipboardhelper;1&quot;].getService(Components.interfaces.nsIClipboardHelper);         clipboardHelper.copyString(text);     } }  But in Internet Explorer it gives a syntax error. In Firefox, it says unsafeWindow is not defined. A nice trick without using : Seeing close-vote details if I've already voted If I've already voted to close a question, it would still be nice to see the details of others' votes — the suggested migration if it's being marked as off topic, or the suggested duplicate if it's being marked as an exact duplicate, for instance. Instead, I only see "You have already voted to close this question" and the overall category.