My friend is receiving a lot of Stack Overflow account recovery emails. When I checked I came to know that for triggering account recovery only email id is needed. So anyone knows his email ID can send a recovery email to his inbox. Since email ID is something public should we ask some private info like date of birth before sending account recovery email?
Just received ~70 unsolicited password reset mails from Super User, so abusive...
Determinant of a block lower triangular matrix I'm trying to prove the following: Let $A$ be a  $k\times k$ matrix, let $D$ have size $n\times n$, and $C$ have size $n\times k$. Then,  $$\det\left(\begin{array}{cc} A&amp;0\\ C&amp;D \end{array}\right) = \det(A)\det(D).$$  Can I just say that $AD - 0C = AD$, and I'm done? Is there a travelling speed of for electric field? If yes, what is it? Consider two circuits containing a battery, bulb, switch and conducting wires but of length 1 meter in one case and 1000KM in other. When switched on at the same time both the bulbs glow instantaneously. I think it is because, electric filed travels from positive terminal of battery to negative terminal through wire almost instantaneously.  My question is there any speed for this electric field? If yes, what is it? By any modification in this circuit is it possible to induce any delay in glowing the bulb? QGIS color polygon according to points I have two layers. Layer 1 contains points (x,y) and layer 2 contains one polygon. All points in layer 1 are positioned within the polygon of layer 2. The points in layer 1 contain an attribute with information on the topography/elevation at the specific point. Can I color the polygon in layer 2 based on attributes from the points in layer 1 in order to create an elevation map? I have a long-running Python server and would like to be able to upgrade a service without restarting the server. What's the best way do do this?  if foo.py has changed:     unimport foo  &lt;-- How do I do this?     import foo     myfoo = foo.Foo() Regaining control of a group after being removed by another admin I created a Facebook group and was later removed by another admin.   How do I get my group back? Difference between SQL batch, statement and RPC? What is the difference between SQL batch, T-SQL statement and Remote Procedure Call? How can I tell if part of the T-SQL code is a batch or statement? Understanding Dirac's notation How can I find the XY coordinates of an HTML element (DIV) from JavaScript if they were not explicitly set? Since I've a database systems examination in less than 3 hours (from now), I have been browsing Stack Exchange network for questions with normalisation and related tags. Most of the questions are now closed as  or others from the list.  Since, these questions are closed, no users are allowed to post answers to them (unless they are reopened). Why am I, then, allowed the option to protect such questions? Doesn't that beat the entire purpose behind "protecting" a question? Convert shapely polygon coordinates I am trying to work with a shapefile using shapely, fiona and python. The original coordinate system is in latitude and longitude that I am trying to convert to state plane system. So I want an updated shapefile with coordinates as statePlane. I converted the json object:  fc = fiona.open("sample.shp")    geoJsonObj = shapefile_record['geometry'] array_coordinates = np.array(geoJsonObj['coordinates']) array_newCoordinates = copy.deepcopy(array_coordinates) for counter in range(0,len(array_coordinates[0])):     long,lat = p1(array_coordinates[0][counter][0],array_coordinates[0][counter][1])     #where p1 is a function to do the conversion     array_newCoordinates[0][counter][0] = long     array_newCoordinates[0][counter][1] = lat  geoJsonObj['coordinates'] = array_newCoordinates.tolist()   when i check the coordinates, i get state plane coordinates according to the transformation.  n. However, when i open the individual shapes/polygons within the shapefile, the coordinates are still latitude and longitude. why does this happen?  ----EDIT 1-----  from pyproj import Proj, transform import fiona from fiona.crs import from_epsg  dest_crs = from_epsg(4269) shape = fiona.open("Sample.shp") original = Proj(shape.crs) # EPSG:4326 in your case destination = Proj('+proj=lcc +lat_1=36.41666666666666 +lat_2=35.25      +lat_0=34.33333333333334 +lon_0=-86 +x_0=600000 +y_0=0 +ellps=GRS80 +datum=NAD83  +no_defs') with fiona.open('new.shp', 'w', 'ESRI Shapefile',shape.schema.copy(),crs = dest_crs) as output:     for feat in shape:                print feat['geometry']['coordinates']         for counter in range(0,len(feat['geometry']['coordinates'][0])):             long,lat =  feat['geometry']['coordinates'][0][counter]             x,y = transform(original, destination,long,lat)             feat['geometry']['coordinates'][0][counter] = (x,y)         output.write(feat) Unique constraint that allows empty values in MySQL Delete hiberfil.sys on Windows 7 Ok, so I know what hiberfil.sys is, and I want to use hibernation on my laptop.  But I have another hard drive active in my laptop, it's taken from my old one... and I want to get rid of the hiberfil.sys on that drive. But even with admin privileges I can't delete it.  Any ideas? Onomatopoeia for disgust How do I add an APN via ADB? For hardware reasons (My menu key doesn't work) I can not add an APN via settings. I read  about using sqlite and  about using code. But I need a more convenient way to do it. I need to do it using adb. I've used git clone to make a local copy of a GitHub repository containing a  I'd like to use. The local copy contains all of the source for the program; but as a newbie to Ubuntu, I've no idea of what tools or steps are involved in compiling and installing the driver.   I'd really appreciate if anyone could provide a step-by-step guide? Reference — What does this symbol mean in PHP? Removing all fraction symbols like “¼” and “½” from a string How to log out user from web site using BASIC authentication? How would you evaluate $\liminf\limits_{n\to\infty} \ n \,|\mathopen{}\sin n|$ How would you evaluate the limit inferior of the sequence $n\,|\mathopen{}\sin n|$? That is, $$\liminf\limits_{n\to\infty} \ n \,|\mathopen{}\sin n|$$    Edit. Let $\mu$ be the irrationality measure of $\pi$. Since $\mu$ is not known, I will split the question:   Assuming $\mu &gt; 2$, what is $\liminf\limits_{n\to\infty} \ n\,|\mathopen{}\sin n|$? Assuming $\mu = 2$, what is $\liminf\limits_{n\to\infty} \ n\,|\mathopen{}\sin n|$?     I kind of like its graph... Prove that a finite union of closed sets is also closed Let $X$ be a metric space.  If $F_i \subset X$ is closed for $1 \leq i \leq n$, prove that $\bigcup_{i=1}^n F_i$ is also closed.  I'm looking for a direct proof of this theorem.  (I already know a proof which first shows that a finite intersection of open sets is also open, and then applies De Morgan's law and the theorem "the complement of an open set is closed.")  Note that the theorem is not necessarily true for an infinite collection of closed $\{F_\alpha\}$.  Here are the definitions I'm using:  Let $X$ be a metric space with distance function $d(p, q)$.  For any $p \in X$, the neighborhood $N_r(p)$ is the set $\{x \in X \,|\, d(p, x) &lt; r\}$.  Any $p \in X$ is a limit point of $E$ if $\forall r &gt; 0$, $N_r(p) \cap E \neq \{p\}$ and $\neq \emptyset$.  Any subset $E$ of $X$ is closed if it contains all of its limit points.