Need to download Census 2010 population,aging and housing information at block group level
Downloading US Census data?
Do web designers need to know how to code? As a web developer, both front-end and back end architect, I work with many different designers and sometimes find it frustrating working with design comps where no thought was put into how to accomplish the design in basic CSS and HTML.  On the other hand as a developer I'm expected to be able to produce code from any design.  Do web designers need to know basic modern CSS and HTML techniques?  Why or why not is this important for a well rounded web designer?  Some general thoughts:   Front end web developers should be skilled enough to code up any design. Web designers should have an understanding of how users will actually interact with their design. Design shops would rather have designers design and leave all the coding up to the developers. In the following method definitions, what does the * and ** do for param2?  def foo(param1, *param2): def bar(param1, **param2): Raised index of partial derivative I am having a really hard time wrapping my head around component notation for tensor fields. For example, I do not know exactly what the following expression means $$\partial_\mu\partial^\nu \phi, \tag{$\#$}$$ where $\phi$ is a scalar field. On the one hand $\partial^\nu=g^{\lambda\nu}\partial_\lambda$ where $g_{\mu\nu}$ is the Minkowski metric, and hence we could write explicitly $$\partial_\mu\partial^\nu \phi=\sum_{\mu,\nu,\lambda}g^{\lambda\nu}\partial_\mu \partial_{\lambda}\phi=\sum_{\mu,\nu}\partial_{\mu}\partial_{\nu}\phi=\partial_\mu\partial_\nu\phi. \tag{$*$} $$ On the other hand, we may think of $\partial_\mu\partial^\nu=g(\partial_\mu,\partial^\nu)=\delta_\mu^\nu;$ so that $\partial_\mu\partial^\nu\phi=\phi?$ Maybe? I am actually not sure of what this would mean. I am really confused. Any help is appreciated. Edit: To give context of where this expression comes from: I was computing the Lagrangian $$\mathcal L=\frac{1}{2}(\partial_\mu\phi)(\partial^\mu \phi) $$ considering an infinitesimal spacetime translation $x^ \mu\to x^\mu-\alpha a^\mu$. The scalar field thus transforms like $\phi(x)\to \phi(x)+\alpha(\partial_\mu\phi(x))a^\mu.$ Plugging thins into the Lagrangian yields the term I am referring to. Edit 2: The change in placement of indices are actually my doubts. I try to elaborate. I do not have any background in using indices to talk about tensors. I am used to interpret the expressions $\partial_\mu$ as the local vector field defined in some chart (local coordinates). I think about vector fields $X$ as abstract section of the Tangent bundle, which restricted to local coordinates can be expressed as $X=X^\mu\partial_\mu$. In the context of QFT, as far as I understand, the symbol $\partial_\mu$ denotes  $(\partial_t,\nabla)$ in the local coordinates $(t,x,y,z)$. So that $\partial_\mu\phi=(\partial_t \phi,\partial_x \phi,\partial_y\phi,\partial_z\phi)$. This was supposed to be my justification on why I wrote the summation on $\mu$ and $\nu$ in $(*)$, but now I note that this only applies when $\mu$ or $\nu$ appear twice, indicating the scalar product; which leads me to the last remark. I think of $g_{\mu \nu}$ as the component of the matrix $$g=\begin{pmatrix} 1&amp;0&amp;0&amp;0\\ 0&amp;-1&amp;0&amp;0\\ 0&amp;0&amp;-1&amp;0\\ 0&amp;0&amp;0&amp;-1\\ \end{pmatrix}$$ which represents the pseudo-Riemmanian metric, which by definition acts on tangent vectors, i.e. linear combinations of the $\partial_\mu$ applied to a point. This is where my doubt comes, in which was the right way to interpret the notation; in particular what is the expresion $(\#)$ in explicit coordinates? Which is correct: "he don't" or "he doesn't"? Which one is correct in a sentence?        He don't    He doesn't      I guess "he doesn't" should be correct because he is third person singular but I've seen some people using do with he. Which one is correct? Evaluating the sum $\sum_{n=1}^{\infty}\dfrac{(-1)^{n}}{n^{2}}$ I am tasked to evaluate the sum  $$\sum_{n=1}^{\infty}\dfrac{(-1)^{n}}{n^{2}}$$ Using contour integration. This is what I've done so far.   Let $C_{N}$ be the square defined by the lines $x=\pm(N+\tfrac{1}{2})\pi$ and $y=\pm(N+\tfrac{1}{2})\pi$. Let $f=\tfrac{1}{z^{2}\sin(z)}$. I was able to prove that  $$\int_{C_{N}}\dfrac{1}{z^{2}\sin(z)}dz=2\pi i\left[\dfrac{1}{6}+2\sum_{n=1}^{N}\dfrac{(-1)^{n}}{\pi^{2}n^{2}} \right]. $$  By Cauchy's residue theorem. So now if I could prove that he integral converges to zero then I would be done. The problem is that I can't seem to get an upper bound on the integral. I've having trouble with the fact that $|f|$ is unbounded within $C_{N}$ so ML inequality doesn't help me. Any hints would be great. Thanks. Detect browser language in Rails If two gravitational waves came in contact with each other what would happen? In another question entirely, what happens when a higher gravitational field interacts with a weaker one. What is the antiderivative of $e^{-x^2}$ I was wondering what the antiderivative of $e^{-x^2}$ was, and when I wolfram alpha'd it I got $$\displaystyle \int e^{-x^2} \textrm{d}x = \dfrac{1}{2} \sqrt{\pi} \space  \text{erf} (x) + C$$  So, I of course didn't know what this $\text{erf}$ was and I looked it up on wikipedia, where it was defined as:   $$ \text{erf}(x) = \dfrac{2}{\sqrt{\pi}} \displaystyle \int_0^x e^{-t^2} \textrm{d}t $$   To my mathematically illiterate mind, this is a bit too circular to understand. Why can't we express $\int e^{-x^2} \textrm{d}x$ as a 'normal function'? Also, what is the use of the error function? Duplicate objects transformation applies to both objects I'm facing this frustrating "feature" that I can't seem to remedy; when I duplicate an object (and now, even when I create two completely new objects), their transformations/scaling is synchronized. This is extremely annoying when trying to use any sort of transformation keyboard shortcut.  It should be noted by going to the properties menu (N) and manually setting the properties works just fine.  For instance, here is just the camera selected (trust me, I made sure):   And when I try to transform by clicking+dragging on the X axis OR by hitting G->X, this happens:   They are not grouped (verified by going to the Groups list up in the Scene panel) and they do not have parents (verified by going to Object->Relations).  I have tried the unlink command as well, to no avail.  I have seriously run out of options; what did I change to have my G->X shortcuts transform multiple objects? It seems completely at random, too; certain objects seemed to be "linked" to other random objects, and this "linking" is guaranteed when duplicating even when I do a non-linking duplicate (Shift+D).  What gives? What are tag badges? How do they work? I've created a series of DEM files using the  tool from LAStools; however since I don't have a licensed version they have black streaks running across them. Does anyone know a good method for removing these streaks? "If I would have lost you" vs "If I had lost you" I watched a (Hollywood?) film the other day where a character visiting his just-hospitalised wife (who it seems will actually survive) says "If I would have lost you [I don't know what I'd do]".  I'd always thought this was an error made by non-native speakers (I myself would only expect "If I had lost you"), but there was nothing to suggest that in the movie. Is it a regionalism?  EDIT: Actually, that wasn't true about only expecting "If I had lost you". I'd have been perfectly happy with "If I'd have lost you", so long as I didn't think too hard about what was being elided. I'd usually elide "have" there to just a schwa (neutral vowel) anyway, and think no more about it. Novel, group transported to a fantasy world, wild/chaos magic I was reading  and was strongly reminded of a series I remember reading in my teens.  This would have been a series of novels (possibly just one), published in English, and likely before 1980 - I read it in the 90s and it was fairly old, a used book.  I do not think it is the same as the linked question, which is why I'm asking this separately.  It was definitely a fantasy, not sci-fi.  Plot:  At least two girls (and possibly also some boys/other girls) are transported from modern Earth into a fantasy world.  I think they're a group of friends, possibly with some romantic pairings, and are in the 16-25 age range.  The first significant scene I remember is two of the girls ending up in a city, where they are taken in by an older female artist (might have been a different creative type, like a sculptor/actress).  She's lesbian/bisexual.  At some point she attempts to give one of the girls a love potion, but they reverse it on her, so instead the artist falls in love with the girl and accompanies her for the rest of the books.  Twist: It's later revealed that the artist's friends recognized the love potion and removed it.  She pretended to be in love and went along because she thought it would be interesting.  At some point at least one of the girls ends up basically being a magical sex slave/prostitute.  I remember her being tattooed or painted - I think in blue - and also possibly given some magical jewellery/piercings that ensure her obedience/love of her owner.  I do not remember much of the over-arching plot, just a few disjointed pieces:  The world has chaos/wild magic storms.  The books might have called them something else.  Anyone or anything caught by these storms is transformed into something else entirely, so different objects or species.  These show up throughout as minor plot encounters.  I think they can be defended against with a special material.  Near the very end, a large storm engulfs a major city, giving it entirely new architecture and transforming the inhabitants into green, hermaphrodites with a centaurish body structure.  I am not 100% sure this was the same novel, but I recall a secondary character with a secret - at night he turns into a woman (not just his body, but an entirely different person).  At some point it's revealed that the woman was his lover, and he saved her life by sharing his body with her - of course, now they can never meet/touch again. Difference between sentences using 'was' and 'being'? What is the meaning of below sentences using was and being?     He committed suicide after he was severely beaten up by four teachers. He committed suicide after being severely beaten up by four teachers. Why two objects get charged by rubbing? How to use z-index in svg elements? Necessary and sufficient condition for the matrix $A = I - 2 x x^t$ to be orthogonal "Will + be + verb -ing)" vs "Will + verb" ? Can someone explain me the constructions (or however they are called) with the "Will + be + verb -ing)" and the "Will + verb" ? Probability of a painted cube being reassembled into itself Suppose 27 cubes are stacked together, suspended in the air, to form a larger cube.  The cube is then painted on all the exposed surfaces and dried.  The smaller cubes are then randomly permuted in both spatial position and spatial orientation to form another large cube.  What is the probability that new larger cube is identical to the original?  This is not homework, it was passed on by a friend who found it somewhere on the internet, and they do not remember where. Syntax error while defining an array as a property of a class