I've already done open the billing information , but the thing is "none" doesn't exists , there only "visa , master and Amex"
I already have an Apple ID, made at Apple.com. Now, when I want to access the App Store from my iPad, I am told that I have to review my information. On the credit card page, I am not presented with a "None" option, even though I am in the United States.   What can I do to proceed without entering this information?
I use VirtualBox on my MBP and often need to mount my USB flash drive inside the guest.  The problem I'm running into is that the host OS (OS X Mavericks) immediately mounts the USB flash drive when I insert it.  When I try to unmount it (gracefully, through Finder), OS X complains that the device is in use.  Further research into lsof reveals that Spotlight and AVG are doing their thing with the flash drive.  Rather than fiddling with individual app settings, I'd like to just modify the host OS behavior so that the USB device doesn't auto-mount.  Any suggestions? Connecting two DC wallwarts in series - to produce dual DC supply I have two 9 V, 300 mA wallwarts and would like to connect them in series to produce +9 V, 0 V and -9 V. This can be done with two 9 V batteries (as seen below), but can I do this with two non-identical wallwarts? I have recently analysed my website with pagespeed addon on firebug. It suggested me to set expiration on CSS, JS and image files.  I am wondering how do i do this? What is the exact difference between a 'terminal', a 'shell', a 'tty' and a 'console'? I think these terms almost refer to the same thing, when used loosely:   terminal shell tty console   What exactly does each of these terms refer to? Insert list of figures in the table of contents Is it possible to create a list of all the figures at the end of a document (this I can do) and make it appear in the table of contents?  So in the the table of content there will be a line saying List of figures ... 19 for example? How can we disable triggers, Validation Rules and workflow rules in salesforce org. [on off - switch] How can we disable triggers, Validation Rules and workflow rules in salesforce org.  This becomes really needed and important when we are doing data migration(data imports) in salesforce.  The way I handled this is create a custom label and include it in workflow and validation rule logic.   example - Custom label 'Disable workflow' = True then do not fire workflows.            if its False then fire workflow  But wanted to understand if there is any more efficient way to handle these scenarios. Java inner class and static nested class What do you call a person who is always online on the Internet? Is there any specific word for a person who is always online on the Internet?  I am just curious to know because staying online is like a profession nowadays. I have come across this .  Has anyone tried anything similar or does it work for you? Can you tell if an email customer / user enters is correct &amp; exists? The following is the first part of Proposition 2.9 in "Introduction to Commutative Algebra" by Atiyah &amp; Macdonald.     Let $A$ be a commutative ring with $1$. Let $$M' \overset{u}{\longrightarrow}M\overset{v}{\longrightarrow}M''\longrightarrow  0\tag{1} $$ be sequence of $A$-modules and homomorphisms. Then the sequence (1) is exact if and only if for all $A$-modules $N$, the   sequence  $$0\longrightarrow \operatorname{Hom}(M'', N)  \overset{\overline{v}}{\longrightarrow}\operatorname{Hom}(M,  N)\overset{\overline{u}}{\longrightarrow}\operatorname{Hom}(M', N)  \tag{2} $$ is exact.   Here, $\overline{v}$ is the map defined by $\overline{v}(f)=f\circ v$ for every $f\in\operatorname{Hom}(M'', N)$ and $\overline{u}$ is defined likewise.   The proof one of direction, namely $(2)\Rightarrow (1)$ is given in the book, which I am having some trouble understanding. So assuming (2) is exact sequence, the authors remark that "since $\overline{v}$ is injective for all $N$, it follows that $v$ is surjective". Could someone explain why this follows?  Given that $\overline{v}$ is injective, we know that whenever $f(v(x))=g(v(x))$ for all $x\in M$, we have $f=g$. I am not sure how we conclude from this surjectivity of $v$.  Thanks! There is a problem with my logic and I cannot seem to point out where. There's a rocket ship travelling at close-to-c speed v without any acceleration (hypothetically), and there is an observer AA with a clock A on Earth, and there's another observer on the rocket BB with a clock B and these two clocks were initially in sync when the rocket was at rest with a FoR (frame of reference) attached to Earth. Now, this rocket's moving and AA tells us that B is running slower than A by a factor of$$ \gamma = 1 /(1-v^2/c^2)^{1/2} $$ $$ t_A/t_B = \gamma $$ where v is the relative 1d- velocity between the two i.e the earth and the rocket! That would mean the time elapsed on A is greater than that on B but this will happen only in the FoR of AA? So $t_B$ in this equation must be the time on B as observed by AA? Is this correct? What do the terms mean in the equations? If the symmetry holds and BB doesn't accelerate, then BB could say that $$ t_B/t_A = \gamma $$ right? where $t_B$ and $t_A$ are the times on B and A with respect to FoR of BB? But I was solving this problem and I took the earth FoR of A, but the prof took the rocket FoR of B? Like how will I know which FoR to solve the problem from? It'd greatly help if the terms in all the above equations were laid down neatly! DO we even need these FoRs?? Because in all the solved problems the prof is't specifying any and is using random ones! Please help!!!! This is the question where I messed up. The first rocket bound for Alpha Centauri leaves Earth at a velocity (3/5)c. To commemorate the ten year anniversary of the launch, the nations of Earth hold a grand celebration in which they shoot a powerful laser, shaped like a peace sign, toward the ship.  According to Earth clocks, how long after the launch (of the rocket) does the rocket crew first see the celebratory laser light?  This must be 25 years. My reasoning is: If v = 3c/5 10v + vt = ct where t is time taken by the light to reach the rocket from Earth as calculated from Earth.. and I solved that for t. and added 10 years to that because the time starts at the launch of the rocket!  According to clocks on the rocket, how long after the launch does the rocket crew first see the celebratory laser light?  This is 20 years. Here, I say: If it takes 25 years as observed by clocks on earth for the laser to reach the rocket, what should be the corresponding time as seen on a clock on the rocket? Using the formula: 25 = $\gamma$t where $\gamma$= 5/4 solved for t!  According to the rocket crew, how many years had elapsed on the rocket's clocks when the nations of Earth held the celebration? That is, based on the rocket crews' post-processing to determine when the events responsible for their observations took place, how many years have passed on the rocket's clocks when the nations of Earth hold the celebration?  For this, I did the following: 10 years on earth = T years on rocket ship where T must be lesser than 10 as observed from Earth FoR! Therefore, T= 4(10)/5 years = 8 years! But, prof says, 10 years on Earth = T years in rocket ship where T must be GREATER than 10 as observed from the rocket FoR??? Therefore, T = 10(5/4) years = 12.5 years!! What does this question actually want? Understanding complete separation for logistic regression Why does logistic regression not converge for a linearly separable data set?   For linear separable data sets the model parameters go to infinity when mimizing the error function (according to Bishop2006, Pattern recognition and machine learning, section 4.3.2). I don't understand why. It must be connected to setting the score function, i.e. the derivative of the error function, to zero.  The error function is given by $E(\mathbf{w})$ as shown in the figure below. Where $\mathbf{t}$ is the target variable vector of the training set and $\mathbf{w}$ the parameter / coefficient vector. The posterior probabiltiy for class 1 is given by  $$y(n) = p(C_1|\mathbf{x}_n) = \sigma(\mathbf{w}'\mathbf{x}_n).$$ Where sigma is the logistic sigmoid function and $\mathbf{x}_n$ is the feature vector for instance $n$ including the predictors.     My second question to logistic regression is if the to posterior probabilities $p(C_1|\mathbf{x}_n)$ and $p(C_2|\mathbf{x}_n)$ sum to one? Prove that the subsequence of a convergent series with nonnegative terms converges The layman's question. Is there a maximum temperature that can be reached by air on Earth due to global warming? For example, one that would prevent living organisms from functioning? I read somewhere that with the increase of the sun's brightness by 10%, the average temperature on our planet will be 47 C. This, however, only for about 600 million years. Would global warming enable reaching such a high average temperature? Iterate enum values using java generics I am using setInterval(fname, 10000); to call a function every 10 seconds in JavaScript. Is it possible to stop calling it on some event?   I want the user to be able to stop the repeated refresh of data. How to completely delete the head of a function expression How should duplicate questions be handled? What should I do when I see a question that is a duplicate of another one?   Should I answer it? Should I downvote it? Should I comment? Should I edit the question to indicate it's a duplicate? If I can, should I (vote to) close the question? What happens when I vote to close as duplicate? Or: Why did a comment with my name on it just appear? Should I flag it for moderator attention? What about similar or related questions? What's the smallest positive integer which is divisible by all integers $1, 2, \dots, n$?  Is there a simple way to represent the answer?  Call it $f(n)$ here.   Clearly factorial ($n!$) satisfies the condition of divisibility.  But once you get to $f(4)$ (which is $12$), factorial ($24$) is too large, because it includes as factors both $4$ and $2$, which are redundant.  Multiplying all the prime numbers up to $n$ gives you another estimate, which is this time too low, because you need to include primes multiple times when they're repeated in the factorization of the inputs.  So the answer is somewhere between factorial, and the product of primes.  Is there a simple answer? Zooming to WMS layer after CQL filter in OpenLayers? I created a layer that contains points and I added it to a map as WMS layer in OpenLayers. I did a CQL filter and it works but I'd like to zoom to the selected point when I worked with getextent or getdataextent it doesn't zoom to the right place. It missed with a few Km. Here is my the code of filter:   function filterNom(){             var filterType ="cql";             var filter = document.getElementById('batima').value;             // by default, reset all filters             var filterParams = {cql_filter: null};             if (OpenLayers.String.trim(filter) != "") {                 if (filterType == "cql")                      filterParams["cql_filter"] = "batiment='"+filter+"'";              }             // merge the new filter definitions             wfs_layer.mergeNewParams(filterParams);             var bounds =  new OpenLayers.Bounds             bounds = wfs_layer.getExtent()             map.setCenter(wfs_layer.getExtent(),18);             var center = map.getCenter();             center.transform(new OpenLayers.Projection("EPSG:4326"), new OpenLayers.Projection("EPSG:900913"));             alert(center.toString()); }   and here is the code to add the WMS layer:    wfs_layer = new OpenLayers.Layer.WMS("Patrimoines",         "http:// localhost/geoserver/cite/wms",          {layers: 'cite:patrimoine' , transparent: true },         {isBaseLayer: false, opacity: 1, singleTile: true, visibility: true,          projection: 'EPSG:900913'});