First difference estimation with time dummy
Is adding a time dummy the same as estimating by within-time fixed effects?
What should I do when Ubuntu freezes? All operating systems freeze sometimes, and Ubuntu is no exception. What should I do to regain control when...   just one program stops responding? nothing at all responds to mouse clicks or key presses? the mouse stops moving entirely? I have an    In what order should I try various solutions before deciding to pull the power plug?  What should I do when starting up Ubuntu fails?  Is there a diagnostic procedure I can follow? Applying Dupli-Objects Is it possible to bake dupliverts into one mesh for the BGE? (I have a large ground landscape that I use as the parent to duplicate trees, and the BGE doesn't support most modifiers.) As a grad student, I just find it tremendously frustrating when emails are ignored by faculty (both at my institution and at other places). Is this acceptable? I'd be content with a simple response with one line along the lines of "I have read this email and am busy right now, will respond in X days when I can write a more detailed email." I understand that, as a first year student in my field, I'm not really in a position to request anything of anyone, but it just seems like common decency.  Instead, I never hear back, as if my email has been jettisoned off into oblivion. Search only for the currently active language Acknowledgements outside of document environment How do I add an acknowledgements section (maybe not specifically \section) outside of (before) my document environment?  in my .cls, there is  \def\@acknowledge{} ... \def\acknowledge#1{\booltrue{@ack} \gdef\@acknowledge{#1}} ... \def\ackpage{ \chapter*{Acknowledgments} \@acknowledge \newpage }   but it seems that I find problems when I put newlines in the  \acknowledge{folks in here}  (see  ) Determine if Term has Grandparent/Great-Grandparent I'm struggling with some concepts in my algebra class. I've chosen these two completely unrelated examples that demonstrate my struggling topics (characteristics and function rings) the two are the following:  $1$) Let $X$ be a set, and let $S$ be a ring. Give a proof that the left distributive law holds for $(S^X, +, *)$.  $2$) Suppose $Y^3 = Y$ for each element $Y$ of a unital ring $R$. Show that $R$ has a finite characteristic d that is a divisor of $6$.  Any example solutions for these proofs would be helpful. Thank you. How Conditional Random Fields and Logistic Regression could be the same? If you have read  tutorial about CRF, on page 4 under the section Classification, it wants to relate CRF to Logistic Regression (or Maximum Entropy, as it is known by this name in NLP community).   The formulation of Logistic Regression is said to be  $ p(y|x) = \frac{1}{Z(X)}exp \{ \lambda_y + \sum_{j=1}^{K}\lambda_{y,j}x_{j}\} $.  On the other hand, on the Wikipedia  for logistic regression, the formulation is  $ f(t) = \frac{1}{1+e^{-t}} $  and the classifier's formulation is the explanation of this formulation which is derived from Logistic Function.  My question is, first, how Logistic Regression and Maximum Entropy Classifier are related to each other and are identical?   Second, the CRF tutorial says Logistic Regression (or Maximum Entropy Classifier) is simple CRF model, how? Proof that every metric space is normal Why is $\langle \textbf R \rangle =Tr \rho R$ here $\rho$ is the state density matrix Evaluate $\lim_{n\rightarrow\infty} \int_0^1 f(x^n) dx$ I have an ASUS K55VM and it came with DOS, and then Windows 7 was installed. I am planning to install Ubuntu on it. My computer had 4 partitions: 240GB, 230GB, 230GB, and 230GB, and I changed this to 5 partitions: 243GB, 230GB, 230GB, 150GB, and 80GB. I installed Ubuntu 12.04 to the 80GB partition through a USB flash drive. It installed fine, however the problem is during the Boot option in Windows Boot Manager. When I choose Ubuntu, this what is displayed:  Windows failed to start. A recent hardware or software change might be the cause. To fix the problem:   1. Insert your Windows installation disc and restart your computer.   2. Choose your language settings, and then click "Next,"   3. Click "Repair your computer." If you don't have this disc, contact your system administrator or computer manufacturer for assistance.    File: \ubuntu\winboot\wubildr.mbr   Status: 0xc000000e   Info: The selected entry could not be loaded because the application is missing or corrupt.   I tried to change the boot option for the OS and made Ubuntu as my first option. It worked, however Windows 7 does not show up in GRUB. In this fear I did the following:     Restarted my PC changed boot option 1 to Windows.   Formatted the drive to which Ubuntu was installed (80GB one) through Windows.   Restarted again.     The problem persists. Windows Boot Manager still shows Ubuntu, and when I choose this it gives two lines one like: grub rescue&gt;, but my Windows 7 is working perfectly fine.  Now I want a solution to remove Ubuntu from the Windows boot option and reinstall completely. Disallow downvoting other answers if I've posted my own Possible Duplicates:        As Dan Dyer mentioned in his comment on , there is a conflict of interest when you have posted your own answer and are allowed to downvote other answers.  Despite the vote editing window being drastically reduced, the fundamental problem remains: I can downvote the other answers permanently and still benefit - my answer gets upvoted ONCE and wham, I have just made up the rep loss for my 10 other downvotes. The vote editing window fixes part of the problem, but there is a more complete fix that has the extra benefit of not preventing legitimate vote changes: to disallow downvotes on competing answers when you have posted one yourself.  The temptation to wrongfully downvote competing answers is huge. The rep loss is tiny in comparison. It has to be in order for people to continue to legitimately downvote.  Details:   If I have previously voted and then post my own answers, delete my downvotes. Continue to allow me to remove the upvotes - I think this is fully legitimate. If I delete my answer it's probably best to continue to deny downvotes (perhaps even including the question), but I don't have a strong opinion either way. Modules over commutative rings I'm trying to get my head around modules, and there's a problem that's bothering me regarding scalar multiplication from the left vs from the right.  In many books/articles I've read, the author may refer to a left $R$-module $M$, and then continue to talk of terms such as $xr$, where $x\in M$, $r\in R$. What is right scalar multiplication in a left module? Does it even make sense to talk about it?  I've been trying to show that over a commutative ring, right scalar multiplication and left scalar multiplication are the same thing, but I've not managed it so far. I've googled it to no avail, and I can't see why the distinction between left and right modules disappears when the base ring is commutative.  Thanks for any replies! Take into account all of the reputations from all stackexchange sites AJAX select returns 'illegal choice detected' Create a settings form for a module in Drupal 8 - when a user selects a View from a list, the drop down under it should populate with the displays in that view.  While the form updates the option list for the user, it also throws an error message on the screen "Illegal choice has been detected".  Here is the code (it doesn't paste very well):    getViewDisplays is the ajax callback that is populating the options.  Some people who have posted about this around the internet say to set #validated on the select field to TRUE, though, that doesn't necessarily feel right. I still want to validate the submission to do some checks. Can I boil milk unattended (and still keep the pan clean)? How to draw a picture by using tikz as backgroud of a character? I am writing some Chinese character and hope to draw simple pictures by tikz and use it as background of this chinese characters. In a short I'd like to get some results as this picture (ignore the lower right noise):    How could I do? Thanks in advance. As an example for least workable code:  \documentclass{article} \usepackage[CJKnumber]{xeCJK} \setmainfont{KaiTi}  \begin{document} \Huge 明月出天山 \end{document} Creating Logo with Fancy Font I am trying to creating a logo that resembles this one shown below, but I do not know the best way of going about it. I know of a fonts package that may be useful, but not sure how to overlay the letters on top of each as so. Would anyone know a neat way of accomplishing this?  Picture of Logo: Logarithm as limit lists this as a limit representation of the natural log:  $$\ln{z} = \lim_{\omega \to \infty} \omega(z^{1/\omega} - 1)$$  Is there a quick proof of this? Thanks