Why java Instance initializers?
How is an instance initializer different from a constructor?
Is radioactive decay spontaneous or random? When it comes to radioactive decay, what is the difference between random and spontaneous?  For example, when the count rate of a radioactive isotope is measured, the readings fluctuate. Is this a demonstration of the randomness of the process, or of its spontaneous nature? Cannot Add, Remove, Move, or Drag icons from Dock I'm using OS X Yosemite (10.10.2) and recently I have been unable to drag or move any items on the dock. Right clicking them gives no option for "remove from dock", and the icons cannot be rearranged. New icons cannot be added, old icons cannot be deleted.  I have tried restarting, and resetting dock preferences to default, and killall Dock, as suggested by earlier askers. None of it works.  I heard about problems with PushBullet - but I do not have PushBullet. Just in case, I deleted a lot of random applications. Still nothing works.  I've tried various commands from lots of answerers on other questions. I've consulted the Mac Help pages. Nothing.  Does anyone know how I can resolve this? After resetting my Dock in an attempt to fix it, it is now filled with the default icons too. This is really limiting my productivity. I recently made changes to my fstab file and, upon reboot, noticed I had an error in it. I get the typical mount error on boot. I went to try and modify it by entering the read-only mode but then, since it's read only, I can't access it. Is there a way around this or some way to delete the file so I can use the backup (which I'm pretty sure works)? As a lab assignment I have to replicate experiment with spring oscillations, and eventually calculate spring constant. The measurements I took are: spring displacement from equilibrium $x$, mass of weights $m$, and period $T$. And presumed uncertainties: $\Delta_\alpha(x)=1[mm]$, $\Delta_e(x)=2[mm]$,  $\Delta_\alpha(t)=0.1[s]$,  $\Delta_e(t)=1[s]$. Where $\alpha$ stands for uncertainty of used equipment, and $e$ is readings uncertainty made by me.  I calculated the standard uncertainty using this formula: $$\sqrt\frac{\Delta_\alpha(x)^2+\Delta_e(x)^2}{3}$$ Which produced $u(x)=1.29[mm]$. Then using the following substitutions:  $$F=kx$$ $$mg=kx$$ $$x=\frac{g}{k}m$$ I assert that:  $$tan(a)=\frac{g}{k}$$  Because in this part of experiment I plotted $x=f(m)$, using excel's linest, I get the slope $s$  $$tan(a)=\frac{g}{k}=s$$  Now, my question is, since I had uncertainty for $x$ introduced, and it is used to compute $tan(a)$, then the latter is affected and should have uncertainty of itself? How in this case should I go about propagating uncertainty to $tan(a)$? Installing an addon There is this addon that was built called Window Generator 2. It can be . However, when I go to the download link it shows up in a new tab as a bunch of code.  How can I download and use this addon in Blender? Add air resistance to projectile motion I am given an initial x and y position and initial velocity and I was asked to graph the trajectory in 1 second intervals.  This is what I have so far:  If $x_0 = 1, v_{0x} = 70, y_0 = 0, v_{0y} = 80, a_x = 0, a_y = -9.8$, and time will be 0,1,2,3... and so on.  Using these equations on every second you can find the plot will be a bell shaped with the highest point being ~ 325 m at about 600 seconds:   $$ x = x0 + (v_{0x})t + 1/2((a_x)t^2) $$ $$ y = y0 + (v_{0y})t + 1/2((a_y)t^2) $$  Usually in physics, we are taught in perfect condition with no air resistance. But what if there was air resistance? How would it affect this problem? How can i add it to my calculations and see what the difference is? How can I find unused functions in a PHP project Find and extract a number from a string Probability of people attending same and different places $5$ tourists plan to attend Octoberfest. Each attends a location at random from the choices: Alpine, Bingeman, Concordia, Kitchener, Queens, Schwaben, Transylvania. Q What is the probability that two attend one location and three attend another same location?  I get that there are $\binom{5}{2}$ possibilities to create 2 groups. There are $\binom{7}{2}$ ways to choose 2 places so shouldn't it be $\frac{\binom{7}{2}\binom{5}{2}}{7^5}$? Administrator URL '&' changed to '&amp;' Is color undefined I want to check whether a color has been previously defined, consider the below code which doesn't execute.  \documentclass{article}  \usepackage{xcolor} \newcommand{\colorprovide}[2]{\ifx\undefined{#1}\colorlet{#1}{#2}\fi}  \begin{document}     %Initial Definition     \colorprovide{mycolor}{red}     \textcolor{mycolor}{Test 1}      %Will overwrite     \colorlet{mycolor}{green}     \textcolor{mycolor}{Test 2}      %Should NOT overwrite as it exists     \colorprovide{mycolor}{red}     \textcolor{mycolor}{Test 3} \end{document}   In other words and analogous to \providecommand{...} not renewing an existing command if it exists, I need a macro which will will NOT redefine a color if the color has already been defined.  The above code throws an error as the logical checking part \ifx\undefined... is incorrect. Who created the veil in the death chamber, and why? Was the veil created by someone or was it always there in HP? What is its purpose? If one can't communicate with the dead through the veil, then what/how do unspeakables learn from the the veil? (except investigating how does it flutter,I suppose,,,,) How to run sudo command with no password? How does the ubuntu user on the AWS images for Ubuntu Server 12.04 have passwordless sudo for all commands when there is no configuration for it in /etc/sudoers?  I'm using Ubuntu server 12.04 on Amazon. I want to add a new user that has the same behavior as the default Ubuntu user. Specifically I want passwordless sudo for this new user.   So I've added a new user and went to edit /etc/sudoers (using visudo of course). From reading that file it seemed like the default ubuntu user was getting it's passwordless sudo from being a member of the admin group. So I added my new user to that. Which didn't work. Then I tried adding the NOPASSWD directive to sudoers. Which also didn't work.   Anyway, now I'm just curious. How does the ubuntu user get passwordless privileges if they aren't defined in /etc/sudoers. What is the mechanism that allows this? $(\mathbb R, \oplus)$ is a group. Define a multiplication with which we get a field. Where $a \oplus b = a + b +1$ I have this problem from the book Real Analysis of Miklos Laczkovich ():     Let $\oplus : \mathbb R \times \mathbb R\to \mathbb R $, where $(a,b) \mapsto a + b +1$. Then,  $(\mathbb R, \oplus)$ is a group. Define a multiplication with which we get a field.   But in the exercise there are no hints. Could anyone help me? Every time Windows 10 runs updates (which I see no way to control), it updates my graphics driver.  I like the old one because it is faster.  So, I have to reinstall it.  This is getting to be a pain.  Is there any way to stop Windows 10 from updating it again? My Bridgestone MB-5 currently has a 7-speed rear wheel. I'd like to convert it to a 10-speed. Is this possible? Is it practical? Vertex cover in a graph with maximum degree of 3 and average degree of 2. Why do rainbows have distinct colors? About the term $-\nabla_{[u,v]}w$ in the definition of Riemann curvature tensor Selecting LiDAR return point type in LiDAR dataset with ArcPy? I am trying to create a Digital Earth Model (DEM) using ArcPy under ArcGIS Pro 2, but I am running into some problems.   I can generate a DEM within ArcGIS Pro by selecting only the ground points under LAS files in the LAS dataset properties, but when I try to run the same code within ArcPy, it generates a DEM using all the points.   Any ideas how you select the return point type in ArcPy?   Here is the code that I have used.  arcpy.conversion.LasDatasetToRaster(lasd, "Test_arcpy_dem", "ELEVATION", "BINNING AVERAGE LINEAR", "FLOAT", "CELLSIZE", 10, 1)   As I said, this generates two different outputs, depending if I am in ArcGIS Pro or not.