Free space on volume rapidly disappearing!
How can I figure out what's slowly eating my HD space?
Automatically updating column in feature class when another column is changed? I have a feature class in a file geodatabase and it contains a field called [curing] in short integer type and another field called [IsPopulated] in short integer as well.  What I want to achieve is to make [IsPopulated] automatically populated with "0" or "1" depending on whether the [curing] column is filled with a numeric value.  "Field Calculator" does not help as it's just a one-off operation and NOT automatic. How to remove \xa0 from string in Python? Why is oil a better lubricant than water? How come mineral oil is a better lubricant than water, even though water has a lower viscosity?    When two surfaces slide over each other with a gap filled with a fluid, the different layers of the fluid are dragged at different speeds. The very top layer touching the top metal surface will have the same speed as the surface itself, while the bottommost layer is stationary. The speed in the layers between is distributed linearly and there exist friction forces between those layers that slow the movement. Those frictional forces should be reduces however, if a fluid with a lower viscosity is chosen.   How come this is not so?   Does it have to do with water's polarity, so that it sticks to surfaces in a different way than oil? I searched for links__system_main_menu, but just find usages of this theme. Where is it defined? How to evaluate $\int_{0}^{\infty}\exp(-x^2-1/x^2)dx$? Question :  $$\int_{0}^{\infty}\exp(-x^2-1/x^2)dx=?$$  I think the answer is $\sqrt{ \pi/2 \cdot \exp(-2)}$  If I change $-x^2-1/x^2$ to $-(x-1/x)^2-2$ then the above integral becomes    $$\exp(-2)\int_{0}^{\infty} \exp(-(x-1/x)^2)dx$$   integral of $\exp(-x^2)dx$ from $0$ to infinity = square root of $\pi/2$, but then is the   integral of $\exp(-(x-1/x)^2)dx$ from $0$ to infinity=integral of $\exp(-x^2)dx$ from $0$ to infinity ? Prove that if $\gcd(ab,c)=1$, then $\gcd(a,c)=1$. If random variables are drawn from an identical distribution, why doesn't this guarantee they are independent? Why is the gravitational force always attractive? Is there another way to explain this without the curvature of space time?   PS: If the simple answer to this question is that mass makes space-time curve in a concave fashion, I can rephrase the question as why does mass make space-time always curve concavely? Why are the holodecks on Voyager in use if they have energy issues? I'm watching the first two seasons of Voyager and various episodes have commentary on having energy limitations -- but we constantly see crew using extremely complicated holodeck simulations. Why would they allow use of the holodeck if they need to conserve energy? Most efficient way to check for DBNull and then assign to a variable? This question comes up occasionally, but I haven't seen a satisfactory answer.  A typical pattern is (row is a DataRow):   if (row["value"] != DBNull.Value)  {       someObject.Member = row["value"];  }   My first question is which is more efficient (I've flipped the condition):    row["value"] == DBNull.Value; // Or   row["value"] is DBNull; // Or   row["value"].GetType() == typeof(DBNull) // Or... any suggestions?    indicates that .GetType() should be faster, but maybe the compiler knows a few tricks I don't?  Second question, is it worth caching the value of row["value"] or does the compiler optimize the indexer away anyway?  For example:    object valueHolder;   if (DBNull.Value == (valueHolder = row["value"])) {}   Notes:   row["value"] exists. I don't know the column index of the column (hence the column name lookup). I'm asking specifically about checking for DBNull and then assignment (not about premature optimization, etc.).   I benchmarked a few scenarios (time in seconds, 10,000,000 trials):  row["value"] == DBNull.Value: 00:00:01.5478995 row["value"] is DBNull: 00:00:01.6306578 row["value"].GetType() == typeof(DBNull): 00:00:02.0138757   Object.ReferenceEquals has the same performance as "=="  The most interesting result? If you mismatch the name of the column by case (for example, "Value" instead of "value", it takes roughly ten times longer (for a string):  row["Value"] == DBNull.Value: 00:00:12.2792374   The moral of the story seems to be that if you can't look up a column by its index, then ensure that the column name you feed to the indexer matches the DataColumn's name exactly.  Caching the value also appears to be nearly twice as fast:  No Caching: 00:00:03.0996622 With Caching: 00:00:01.5659920   So the most efficient method seems to be:   object temp;  string variable;  if (DBNull.Value != (temp = row["value"]))  {       variable = temp.ToString();  } Can somebody tell me why the counting measure (so, if $S=P(X)$, then $\mu(A)$=infinity if $A$ isn't finite and $\mu(A)=$#$A$ if $A$ is finite) is a measure? (The second property of a measure isn't clear for me). grub2 not able to find the new kernel This is very strange issue, i have CentOS7 running on HP server and everything was working till date until i did "yum install kernel" after reboot it drop me in grub&gt; shell that means it won't able to read or find grub.conf file.   in grub&gt; i found grub.conf has still old files there is no new entries of new kernel   I did this, and found there is no new kernel entries but if i boot with old kernel then i can see latest grub.conf (with new kernel)  grub&gt;cat /grub2/grub.conf   Question: where grub2 getting that old file from? why it's not able to find new kernel ? Is it mandatory to have published papers while applying for PhD? I've heard from people saying that while applying for PhD, you need to have past experience in researching something and should have international publications. I was like more concentrated towards practical experience and have't had any publications. If I am aspiring to do PhD and want to apply, it would be impossible if such a criteria exists! Constants of motion vs. integrals of motion vs. first integrals Since the equation of mechanics are of second order in time, we know that for $N$ degrees of freedom we have to specify $2N$ initial conditions. One of them is the initial time $t_0$ and the rest of them, $2N-1$ are initial positions and velocity. Any function of these initial condition is a constant of motion, by definition. Also, there should be exactly $2N-1$ algebraically independent constants of motion.  On the other hand, Noether's procedure gives us integrals of motion as a result of variational symmetries of the action. These integrals of motion are also conserved but they are not always $2N-1$ in number. In consequence, we classify the system by their integrability.  So, what is the difference between the  and ? Why do non- have less integrals of motion when they should always have $2N-1$ constants of motion? How to find sum of power series $\sum_{n=0}^\infty\frac{1}{n!(n+2)}$ by differentiation and integration? Let $$ S = \sum_{n=0}^\infty \frac{1}{n!(n+2)} $$  Integrate the Taylor Series of $xe^x$ to show that S = 1  Also, Differentiate the Taylor series of $\frac{e^x - 1}{x}$ to show that S = 1  For the integration one, I got $\int xe^x dx$ = $x^2\sum_{n=0}^\infty \frac{1}{n!(n+2)} x^n$ and pretty much stuck. I can see the S term but i have no idea how to move on from there How can I find more music similar to the ones I like? Moving status bar in iOS 7 When using the \cite command in figure captions and the ieeetr bibliography style, then  BibTeX numbers the citations as appearing earlier than they do in reality (i.e. the first citation in the document ends up being [42]).  Is there any way to get BibTeX to ignore the \listoffigures section when numbering? How to maintain a file's 'last modified' date? Why didn't Doc remember Marty's outfit? In Back to the Future 3, Doc (from 1955) sends Marty back in time wearing a cowboy outfit.  But then, Doc (from 1885) doesn't remember that it was him who offered this outfit to Marty.   Does this mean there are two different Docs (from differing timelines) or is it the same Doc but he somehow forgot the outfit.