I do not find it cozy to leave footprints on Facebook, Google and alike upon every single step I do on the Internet. For this purpose I use a script blocker. Now I found that Stack&nbsp;Overflow does not allow login without allowing it to use ajax.googleapis.com.  Why does Stack&nbsp;Overflow require JavaScript from Google in order to work? Which information is forwarded to Google upon acting on Stack&nbsp;Overflow?
What tools and technologies are used to build the Stack Exchange Network?  See also:
Prove $\sum{\frac{1}{(x+2y)^2}} \geq\frac{1}{xy+yz+zx}$ How to do selective-color in Photoshop? How to make the single color in a photography to be color and other parts changed to B&amp;W?.  Don't know exactly the name of the effect, to be more clear in the following photo I want the green part to be green and other parts( leg and sandal) in B&amp;W..    How to achieve that effect in Photoshop? What are the shortcomings of the Mean Absolute Percentage Error (MAPE)? The  () is a common accuracy or error measure for time series or other predictions,  $$ \text{MAPE} = \frac{100}{n}\sum_{t=1}^n\frac{|A_t-F_t|}{A_t}\%,$$  where $A_t$ are actuals and $F_t$ corresponding forecasts or predictions.  The MAPE is a percentage, so we can easily compare it between series, and people can easily understand and interpret percentages.  However, I hear that the MAPE has drawbacks. I'd like to understand these drawbacks better so I can make an informed decision about whether to use the MAPE or some alternative like the MSE (), the MAE () or the MASE (). If I'm logged in to a system via SSH, is there a way to copy a file back to my local system without firing up another terminal or screen session and doing scp or something similar or without doing SSH from the remote system back to the local system? Marriage Tax Benefits input to pic with 12V and resistors I have 12V, Use these 12V to power a device (that has a 12V output signal) and to power a 7805. After the 7805 there is a pic microcontroller where I would have to connect the output from my device. I was thinking of having 2 resistors in a 3/1 ratio in order to have about 4V at the pin of the pic. Can this be done, given that the ground is common, or will it give some sort of problem with the lm7805? I have seen many folks doing this  concluding that shadow from point A on the Moon can travel to point B on the Moon faster than light.  What I fail to understand here (and I am sure I am wrong), is nothing can travel faster than light. I also read about Relativity where Einstein stated that every event happening for you depends on how fast the light gets from where the event is happening to you.  This is my particular problem with this Moon shadow experiment. You cannot make a shadow travel faster than light, because in order for the "disappearance" of light to get to the Moon, it has to travel at light speed.  Here is one way to understand my point. Consider we shine a flashlight on Moon, like the guy in the linked video did, we move the finger across the face of the flashlight, before we moved the finger it was casting the shadow at Point A on Moon, after we finish moving our finger, the shadow is at Point B on the Moon.  When the finger reaches the end of it's moving length, the light waves that have left the flashlight before the finger reached there will have to hit Point B and it will take them a second and a half to get there, and another second and half for us to see that shadow on point B, which makes it 3 seconds + finger moving time for us to actually see the shadow at point B. That means shadow traveled (say) across the diameter of the Moon in 3 seconds.   So. about 3000 Km in ~3 seconds make it 1000 Km per seconds which is very tiny compared to the speed of light. How can these experiments conclude that Shadow could be made to travel faster than light? What is the obvious clue that I am missing here? MiKTeX and Perl scripts (and one Python script) Parent Field in Lightning Datatable Are Parent Fields supported in lightning Datatable?  I'm trying to display Account Name with Contact information, but it seems parent fields are not supported in lightning datatable.  Component:  &lt;aura:component controller="PagingSortingController"&gt;     &lt;aura:attribute name="mydata" type="Object"/&gt;     &lt;aura:attribute name="mycolumns" type="List"/&gt;     &lt;aura:handler name="init" value="{! this }" action="{! c.init }"/&gt;     &lt;lightning:datatable data="{! v.mydata }"          columns="{! v.mycolumns }"          keyField="con.id"         onrowselection="{! c.getSelectedName }"/&gt; &lt;/aura:component&gt;   Controller:  ({     init: function (cmp, event, helper) {     cmp.set('v.mycolumns', [                 {label: 'Contact Name', fieldName: 'Name', type: 'text'},                 {label: 'Phone', fieldName: 'Phone', type: 'phone'},                 {label: 'Email', fieldName: 'Email', type: 'email'},                 {label: 'Account Name', fieldName: 'Account.Name', type: 'text'}             ]);         helper.getData(cmp);     }  })   Helper:  ({     getData : function(cmp) {         var action = cmp.get('c.getContacts');         action.setCallback(this, $A.getCallback(function (response) {             var state = response.getState();             if (state === "SUCCESS") {                 cmp.set('v.mydata', response.getReturnValue());             } else if (state === "ERROR") {                 var errors = response.getError();                 console.error(errors);             }         }));         $A.enqueueAction(action);     } })   Apex Controller:  @AuraEnabled     public static List&lt;Contact&gt; getContacts() {         List&lt;Contact&gt; contacts =                  [SELECT Id, Name, Phone, Email,Account.Name FROM Contact];         return contacts;     } Can we have a black hole without a singularity? Assuming we have a sufficiently small and massive object such that it's escape velocity is greater than the speed of light, isn't this a black hole? It has an event horizon that light cannot escape, time freezes at this event horizon, etc. However this object is not a singularity.  If a large star's mass were compressed to the size of, say, a proton, it would certainly have these properties but it would still not be a singularity as a proton does have volume.  The reason "physics breaks down" at singularities is because we cannot divide by zero, but as long as the proton-sized object has volume, physics won't "break down", yet we still have an event horizon and an object that is invisible (but not undetectable) from the outside.  I have read the answers to  related question. I'm not sure if they don't address my specific question or if I don't understand the answers. Are two norms equivalent if they induce the same topology on a vector space? Whenever two norms are equivalent in the sense that $\|x\|_1\le c_1\cdot \|x\|_2$ and $\|x\|_2\le c_2\cdot \|x\|_1$, they generate the same topology. Is the reverse also true, i.e. if a topology is generated by two different norms, are the norms equivalent in the above sense? We know this to be true for $\mathbb{R}^n$, but is it generally true, and if not, what are some counterexamples?  What about a Hausdorff, translationally invariant vector space topology generated by two different metrics, are the metrics equivalent in the sense $d_1(x,y)\le c_1\cdot d_2(x,y)$ and vice versa? Is it permissible to use somebody else's words (without quotations) to describe a concept once their work is cited? Quite often one comes across a really succinct and precise explanation of a concept. I'm wondering if it is permissible to use this explanation verbatim, if the source work is cited in your paper (next to the explanation)? What's in question here is at most 3 sentences. What's the best way of handling permissions for Apache 2's user www-data in /var/www? Has anyone got a nice solution for handling files in /var/www? We're running Name Based Virtual Hosts and the Apache 2 user is www-data.  We've got two regular users &amp; root. So when messing with files in /var/www, rather than having to...  chown -R www-data:www-data   ...all the time, what's a good way of handling this?  Supplementary question: How hardcore do you then go on permissions?  This one has always been a problem in collaborative development environments. I have a repeated composition of functions ${T_n}(z) = {\tau _0} \circ {\tau _1} \circ {\tau _2} \circ  \cdots  \circ {\tau _n}(z)$  By analogy with $\sum\limits_{i = 1}^n {} ,\prod\limits_{i = 1}^n {} ,\bigcup\limits_{i = 1}^n {} ,\bigcap\limits_{i = 1}^n {} ,$ I want to write ${T_n}(z) = \left( {\mathop  \circ \limits_{i = 0}^n {\tau _i}} \right)(z)$ or even ${T_n}(z) = {\mathop  \circ \limits_{i = 0}^n {\tau _i}} (z)$. Can I do this? I am visiting a friend in Switzerland for ten days. I have already got visitor's visa for the same on my Indian passport. Particulars mentioned on my visa are:  1. 'Etats Schengen' , 2. Single entry 3. Dates of visit. &amp; 4. Type of visa : C.  I understand that having already got ‘Etats Schengen' visa, I can travel to all Schengen countries.  I am also planning to visit Paris for a day during my stay in Switzerland. However, I never mentioned this in my visa application. I am planning to take a train from Geneva to Paris and book a hotel in Paris for one night. Can I possibly plan my Paris trip this way as I have Schengen visa, or I am not allowed to travel out of Switzerland as I never mentioned this in my visa application?   Also what does Single entry on my Schengen visa means: does it mean that I can enter and leave Switzerland only once or it means that I can enter and leave the Schengen region only once. Within 300 km of Tokyo: Where for flora, landscape, nature? Openshift application url: example.rhcloud.com  Custom domain: example.com  I came across this  and added the redirection rule. However, I can not access example.rhcloud.com now. My custom domain is www.example.com.  To avoid duplicate content problems, I tried this redirection.   Here is my .htaccess file:  RewriteEngine on   # Uncomment the following lines to force HTTPS #RewriteCond %{HTTP:X-Forwarded-Proto} !https  #RewriteRule .* https://%{HTTP_HOST}%{REQUEST_URI} [R,L]   # WordPress Defaults RewriteBase / RewriteRule ^index\.php$ - [L] RewriteCond %{REQUEST_FILENAME} !-f RewriteCond %{REQUEST_FILENAME} !-d RewriteRule . /index.php [L]  # Redirect Https traffic to Http RewriteEngine on  RewriteCond %{SERVER_PORT} ^443$ [OR] RewriteCond %{HTTPS} on RewriteRule  ^(.*)$ http://%{HTTP_HOST}%{REQUEST_URI} [R=301,L]   # Redirect non-www to www RewriteEngine on  RewriteCond %{HTTP_HOST} !^www\. [NC] RewriteRule ^(.*)$ http://www.%{HTTP_HOST}/$1 [R=301,L]    # Redirect openshift rhcloud domain to custom domain RewriteEngine on  RewriteCond %{HTTP_HOST} ^example.rhcloud.com$ RewriteRule (.*)$ http://www.example.com/$1 [R=301,L]   Why is example.com not redirecting to ww.example.com? How do I fix this?  Also, I see that since I have https to http redirection and non www to www redirection, my blog has been loading slow. How can I reduce it to lesser number of rules?  Edit:  In chrome:   In Firefox:     The page isn't redirecting properly, Firefox has detected that the server is redirecting the request for this address in a way that will never complete.     This problem can sometimes be caused by disabling or refusing to accept cookies. Can you attack with different weapons using Extra Attack? While explaining to my nephew about the physics of light, I told him we cannot see infrared color, and he kicked back with a very simple question: why can't we see it? I could not tell him. Is the human eye unable to sense such light or can it indeed but the brain can't understand the signal? any other reason? How can I prevent SQL injection in PHP?