I left my empty cast iron pan on the stove top for 2 1/2 hrs.  My problem is not a rusty residue, but black that continues to wipe off. What can I do? I have washed with steel wool, rinsed well, but when I wiped with oil, the paper towel continues to wipe black.
I left my cast iron pot on the gas stove, on high flame, and then forgot about it for 3 hours. It was empty and I was drying it before I oiled it to store it. After I discovered it and let it cool, I oiled it with a paper towel and all this rusty stuff came off and continues to come off. Is my pan ruined? What should I do?
limit of integral $n\int_{0}^{1} x^n f(x) \text{d}x$ as $n\rightarrow \infty$ What is a *.pkinfo file?   Google Search results talk about Package Info files and how they contain map documents and layers, so I don't see how this is different from a .mpk file.    I also have not found anything about how to create a *.pkinfo file. How to correctly specify coordinate system? Using QGIS v. 1.9 (1.7 does not seem to be available for Ubuntu Linux 12.04), do the following:   Create new project, specify coordinate system by clicking on button in bottom right hand corner, enable on the fly CRS transformation, set projection to WGS 84 / UTM Zone 18S. Pass mouse over project window and UTM coordinates appear in coordinates window in status bar at the bottom. Add delimited text layer in decimal degrees. When asked for projection, specify same projection as in (1). Points in the layer are plotted but, mousing over the map, the coordinates in the coordinates window are now in decimal degrees (even though the projection is set to UTM).   Is there something I am missing here? I have tried doing this in so many ways, so many times, but the result is always the same. I seem to be setting the projection correctly but only decimal degrees show in the coordinates window.  With thanks, Martin How can I find the cheapest prepaid SIM card for a given country? Extend or remove Data Explorer timeout I know that we don't have automatic login for the Data Explorer, but what's with the automatic timeout/logout?  There have been times that I am logged into the site, maybe I walk away for a little bit, and I come back to being logged out.    Is there a reason for logging us out of Data Explorer?  If so, is it possible to either remove the timeout or extend the period of time before timeout? Can a werewolf turn a muggle into another werewolf? SqlException from Entity Framework - New transaction is not allowed because there are other threads running in the session I have this picture:  (I have the original in Pixen and could export it to several different formats. I went with PNG though since it's lossless.)  When I open my picture in Preview (OS X) and zoom in, it looks fine. The characters have extremely sharp boarders between them and the background. However, when I put it into my LaTeX document, compile it to a PDF (using TeXShop) and then zoom in, it suddenly have gotten blurry (see screenshot: ).  Minimal working example:  \documentclass[12pt]{article} \usepackage{graphicx} \begin{document} \includegraphics[scale=1]{fig1.png} \end{document}   In the end, I would like to be able to scale the picture freely without there being any blurring at all. From a link from the question  to the HP Wikia, I started mulling over something I read about Voldemort and the "regeneration" potion (not a canon potion, but I'll use it for lack of a better way of describing it. . .) and would really like to know:  How did Voldemort drink the regeneration potion to turn his body into the grotesque childlike form we see in Goblet of Fire while he was still in a "mangled spectral state"?  Spectres (i.e. spirits or ghosts) are non-corporeal; they obviously can't consume food or drink liquids. So, how did Voldemort overcome this difficulty and manage to drink the regeneration potion? How to choose trace width for very high current PCB? I am currently designing a PCB layout for my team's high current, high voltage project and am having trouble with choosing my trace width.  The circuit is composed of 12 inductors placed in series with short traces connecting them together (about 5mm max length). We are feeding 10μs pulses at ~300A/1000V at a maximum rate of 10 pulses per second by discharching capacitor banks into the coils. The capacitors are recharged by an external source.  I have looked for resources on the subject, but nothing I could find applies to the level of current and voltage we are applying.  Is there a rule for determining trace width for very high current pulses? Is there any elegant way to show that $\mathbb Q(\sqrt[3]{2}, w)=\mathbb Q(\sqrt[3]{2}+w)$, where $w=e^{i\frac{2\pi}{3}}$.  I was thinking to show that $ 9+9 x+3 x^3+6 x^4+3 x^5+x^6$ is the minimal polynomial of $\sqrt[3]{2}+w$, but checking irreducibility seems a bit tedious. What is a smart pointer and when should I use one? What is a smart pointer and when should I use one? Time indicator is shown as "%a %H:%M" in the center of the top bar.  How do I move it back to the right where it belongs, and make it include the full date and time ("%Y-%m-%d %s %H:%M")? GDAL HDF4 Driver on Linux System I'm running code that works with MODIS HDF4 datasets on a Debian Linux distribution.  I am also running this code on a Windows machine.  On both the Windows and the Linux machines, I have the most recent GDAL version (gdal 1.11.1, np19py27_1), however on the Linux machine, GDAL doesn't seem to recognize HDF4 Drivers... it won't load or process any of the HDF4 datasets that are easily processed on the Windows machine (unfortunately this machine doesn't have enough space to run the full code).  Has anyone else encountered this problem?  Do I need to install an additional module on the Linux system? During the next quarter at uni, I'll be taking a course in real analysis and since I prefer studying with an additional text I thought I'd come here to look for some book recommendations.  My background: I'm comfortable with linear algebra and single variable calculus, but shakey on multivariable calculus. I did have a slight introduction in to geometry.  For linear algebra I found the common recommendation of Hoffman &amp; Kunze to be very helpful (although the abstractness came as a bit of a kicker at first).   For Single variable calculus I used the book Calculus by Adams and Essex, which I found frustrating to work with, because it often left me guessing at what they were trying to do or why they were doing it. I also felt that they exercised a certain lack of rigour. (Which may be due to the subject which would make it hard to derive from axioms.)  Details: Though it would be a complementary text, I'd prefer one which will still hold value as a work of reference at a later point in my studies. I've heard that Rudin's Principles of mathematical analysis is one of the better textst out there, but also read several comments discouraging Rudin's book as a first introduction to real analysis, hence my quest to gather more information and maybe get some more personalised recommendations.  The course: The mandatory course literature will consist of lecture notes, but 4 texts are suggested as recommended reading.   T.M. Apostol, Mathematical analysis. Addison-Wesley (1974) J. Dieudonné, Foundations of Modern Analysis. Academic Press (1960) A. van Rooij, Analyse voor Beginners.Epsilon Uitgaven, no. 6 (2003)   R.S. Strichartz, The way of analysis (1995)   Thanks in advance! Introduction to Statistical Learning defines the F-statistic as follows: $$\frac{(TSS - RSS) / p}{RSS / (n - p - 1)}$$ I am trying to interpret this formula intuitively - the numerator looks like the $ESS$ per regressor, and the denominator looks like the $RSS$ per observation. This does not seem like an apples to apples comparison; can anyone explain why it makes sense?  They also say that the expectation of the denominator is equal to the variance of the irreducible error if the linear model assumptions hold (I get this, as the denominator is really the Residual Standard Error, which is an unbiased estimator). They also say the numerator is equal to the variance of the irreducible error if the null hypothesis is true. Therefore the F-statistic will be close to 1 if the null hypothesis is true.  But if you let p = 1, that is, apply the F-statistic to single linear regression, it becomes:  $$\frac{TSS - RSS}{RSS / (n-2)}$$  According to the book, if the regressor has no explanatory power, the F-statistic should be close to 1. But if you imagine a data set where the coefficient on X is 0 (i.e. no explanatory power), $TSS$ will be equal to $RSS$, so the numerator and hence the F-statistic should be 0, not 1 as they claim. What is going on?  Furthermore, if you accept that the F-statistic is 1, as they claim, then $(TSS - RSS) = RSS / (n-2)$, which means $ESS = RSS / (n-2)$. If you think of the F-statistics as comparing explained vs. unexplained variation, this does not seem like a fair comparison since this decomposition makes it the ratio of TOTAL explained variation summed across ALL observations vs. the unexplained variation PER observation. Again, what am I missing?  I am just trying to make sense of it in a layman way, apologies if I am missing something obvious. What is an undefined reference/unresolved external symbol error and how do I fix it? Linked and Related sections contain duplicate links to questions The Linked and Related sections sometimes contain a link to same same question.  See for example , where one of the Linked questions is same as the first of the Related questions.  I think that this is redundant and duplicate links should be removed from Related section. How can I stop using beta iOS on my iPhone? I'm currently on the beta program on my iPhone. How can I stop using the beta versions and go back to the newest version of iOS (non-beta)? Calling the base constructor in C#