So I intend to take . It takes an immediate action to activate.  I already know questions will come up with my DM when I try to use this ability...  The way I understand the mechanics immediate actions are allowed at any time. So I intend to use Wave Shield once an attack connects and damage dice are to be rolled.  So first off is this correct? I believe it is since immediate actions have no restrictions on when they can be used outside of having already used a swift action or immediate action on your turn, or having used your immediate action for the next turn already!  The second question is slightly more awkward, will this casting of Wave Shield provoke an attack of opportunity? I can't find much on the matter besides   It is practically a sidenote that mentions spells with a cast time of a standard action. Does that mean this spell is immune to attacks of opportunity?
As we all know, immediate actions are just like swift actions, but can be performed outside of one's turn.     However, unlike a swift action, an immediate action can be performed at any time - even if it's not your turn.   However, it is still unclear if one can use an immediate action during someone else's action.  For example:  A monster swings at a conjurer.    Can conjurer abrupt jaunt outside monster's reach right after the attack was rolled, thus wasting an attack?  What about right after the damage was rolled, but not yet applied?  What about casting celerity and baleful transposition on yourself and monster's ally so the monster would hit his ally, given high enough attack roll?   Let's complicate a bit with a complex, full-round action on a monster's side.    Can one use immediate action in between attacks in full attack? What about after movement part of a charge?
Do the electric and magnetic components of an electromagnetic wave really generate each other? Frequently when EM waves are taught, it is said that the change in electric field causes a change in the magnetic field, which then causes a change in the electric field, and so on and so forth.   But from my understanding of basic electromagnetics, it is not necessarily a changing electric field that creates a change in magnetic field, but instead an accelerating charge. and it is this charge that creates both the electric and magnetic field. Again, from my understanding, a changing magnetic field is not generated by a changing electric field, but instead just happens to always be present perpendicular to a changing electric field due to the laws of electromagnetism.   Am I wrong? Or is the "mutual generation" concept between the electric and magnetic components of an EM wave an actual thing? How to properly set up a PDO connection I recently found out about Ubuntu for Android Multi-Core Smartphones and was digging around on the Ubuntu website as well as the Canonical website but have yet to find any information on if it available to the public yet ?  I am very interested to try it our on my Android and if it is available for the public am wondering where and how I can get a copy of "Ubuntu for Android" ?  If it is not available then perhaps someone can shed some lite on what sort of timeframe it will be until it is available to the general public? Help me find the name of a space TV show from the early '90s I don't recall much about the show, and I think I only ever saw one episode, and my Google Fu is not up to snuff today.  The episode, most likely the pilot, came out around the same time as Babylon 5 and then just disappeared.  From what I remember the show was about the (small) crew of a ship. The cockpit of the ship was a upright bed-like contraption, and the cast were investigating a ship that had a radiation leak or something adrift in space.  There was a cast member who could shape-shift, similar to Odo from Deep Space 9, and another member was a barbaric warrior.  There was some sort of mystic stuff, but I may be confusing that with Babylon 5.  Overall the show was very similar, in my memory, to Deep Space 9 and Babylon 5 so I may be confusing things, but I do remember how I saw the similarities in the show to those shows and knew it wasn't the same show.  Any help? I am trying to work through Hartshorne's book and while working through one of the exercises, I need to show the following:  Let $k$ be an algebraically closed field. Let $Y \subseteq A^3$ be the set $Y=\{(t,t^2,t^3)\;|\;t \in k\}$. Show that $Y$ is an affine variety.  The rest of the problem I have completed. I'm just not sure how to show that this set is closed and irreducible. I assume that they intend for $A^3$ to have the Zariski topology. Name "Chapter" is not showed in the table of the content What are the grammatical rules determining whether to use which or what?  I usually go by intuition. It's "What car are you looking at?" and "What bicycle do you like most?" but "Which song did you sing?" Quite often, I don't know whether to use what or which.  How can I tell? How to copy only file attributes (metadata) without actual content of the file? I have read several questions regarding how to fix an already enabled desktop cube or the problems it had in 11.04. But in 11.10, how can I correctly enable desktop cube in Unity 3D? Elizabeth's Brooch - follow-up question The easiest thing to do is [to] call for a taxi Consider a particle in a potential well. Let’s assume it’s a simple harmonic oscillator potential and the particle is in its ground state with energy E0 = (1/2) &#8463;&omega;0. We measure its position (measurement-1) with a high degree of accuracy which localises the particle, corresponding to a superposition of momentum (and therefore energy) states.  Now we measure the particle’s energy (measurement-2) and happen to find that it’s E10 = (21/2) &#8463;&omega;0. Where did the extra energy come from?  In the textbooks it’s claimed that the extra energy comes from the act of observation but I wonder how that could work. Measurement-1 which probed the position of the particle can’t have delivered to it a precise amount of energy, while measurement-2 might just have been passive. No doubt there is entanglement here between the particle state and the measuring device but where, and which measurement? How do I safely investigate a USB stick found in the parking lot at work? I work at an embedded software company. This morning I found a USB stick in the parking lot in front of the building. With all the stories of "dropped USB stick attacks" in mind, I'm obviously not going to just plug it into my laptop. OTOH, I'm curious to know whether this was actually an attempt to compromise our systems, or it's really just an innocent case of somebody accidentally losing a USB stick. How do I safely inspect the USB stick without risking exposure?  I'm worried not just about malware and crafted file system images; there's also stuff like power surge attacks:.  EDIT: Many of the answers seem to assume I want to keep the drive and use it afterwards. I have no interest in that at all, I know USB sticks are cheap, and that it wouldn't be mine to keep anyway. I only want to know whether this was indeed a semi-targeted attack, partly out of curiosity whether this actually happens in real life and not just in security papers, but also so that I could warn my coworkers.  I want to know how I would figure out whether the stick contains malware. And that's not just a matter of looking at the drive contents and seeing a suspicious autorun.inf or a carefully crafted corrupt file system - I very much also want a way to inspect the firmware. I sort-of expected that there were tools for extracting that and comparing to known-good or known-bad binaries. Some months ago I watched  video of Blenderguru about "How to create a realistic earth in blender". In this video blender render is used and  now that I understand texturing in cycles a little better I am trying to rebuild this "realistic earth" with cycles.    In the video - starting at about 11:30 min - it is shown how to map the "earth day" and "earth night" image textures. Depending on the lights shining on the earth the earth or night image is projected. I tried to rebuild that in cycles but I think I a making mistakes. In the circled box the "night" nodes are found. What Is my mistake ?   P.S When you see other mistakes in this node tree, please let me know.  OK ... I now have implemented the advice of Uncle Snail (except moving the black slider). Below an image of the earth and the updated node tree (I also rearranged nodes for better overview).    In the Color Ramp, I did not move the slider. Is that really necessary ?? Let $M_n$ denote the vector space of all $n\times n$ real valued matrices and for any matrix $A\in M_n$ let $A^t$ denote its transpose. Define the linear map $T:M_n\rightarrow M_n$ as $$T(A)=A+A^t.$$ What is the minimal polynomial of $T$? What are the eigenvalues and the corresponding eigenspaces of $T$? What is the characteristic polynomial of $T$?  I learned about minimal polynomials of operators from $\textit{Linear Algebra Done Right}$ by Axler. In his description he explains how in order to find the minimal polynomial you must find the smallest positive integer $m$ such that $T^m$ is a linear combination of $I, T, T^2, \ldots, T^{m-1}$. That is, the smallest integer $m$ such that $$T^m = a_0I+a_1T+a_2T^2+ \cdots +a_{m-1}T^{m-1}.$$  As for the eigenvalues...since we are working with real-valued matrices, then $A$ and $A^t$ have the same eigenvalues, so if $\lambda \in \mathbb{R}$ is an eigenvalue of $A$ (and hence of $A^t$) wouldn't $2\lambda$ be an eigenvalue of $A+A^t$? I apologize if I am saying utter nonsense... When is matrix multiplication commutative? I know that matrix multiplication in general is not commutative. So, in general:  $A, B \in \mathbb{R}^{n \times n}: A \cdot B \neq B \cdot A$  But for some matrices, this equations holds, e.g. A = Identity or A = Null-matrix $\forall B \in \mathbb{R}^{n \times n}$.  I think I remember that a group of special matrices (was it $O(n)$, the ?) exist, for which matrix multiplication is commutative.  For which matrices $A, B \in \mathbb{R}^{n \times n}$ is $A\cdot B = B \cdot A$? Point vs Pixel: What is the difference? What is the difference between points and pixels? What is wrong with this deduction to show that within a multiplet different state has different square angular momentum? I am watching Susskinds's lecture , in which he introduced square angular momentum operator $L^2$, which can be written as $$ L^2=L_z^2+L_-L_++L_z $$ where $$ L_\pm=L_x\pm iL_y $$  Besides, he argued that the spectrum of $L$ can only be $m,m-1,\cdots,-m+1,-m$ in which $m$ is an integer or half-integer. If we denote $|m\rangle$ the eigenvector corresponds to eigenvalue $m$, we have $$ L_\pm|l\rangle=|l\pm 1\rangle\;\text{or}\;0 $$  In the lecture he showed that $L^2|m\rangle=m(m+1)|m\rangle$ for $m$ the highest eigenvalue, by $$ \begin{align*} L^2|m\rangle&amp;=L_z^2|m\rangle+L_-L_+|m\rangle+L_z|m\rangle\\ &amp;=m^2|m\rangle+0+m|m\rangle\\ &amp;=m(m+1)|m\rangle \end{align*} $$  Then he left an exercise to show that for any $-m\leqslant l&lt; m$, we also have $|l\rangle$ is an eigenvector of $L^2$ with eigenvalue $m(m+1)$.  In the lecture, he hinted by showing that it suffices to show that $L^2$ commutes with $L_i$ for $i=x,y,z$, which gives us $$ L^2|m-1\rangle=L^2L_-|m\rangle=L_-L^2|m\rangle=L_-m(m+1)|m\rangle=m(m+1)L_-|m\rangle=m(m-1)|m-1\rangle $$  I believe it is true since I find the   online.   However, my question is that, why the following proof is wrong.  I tried to mimic the proof for $|m\rangle$ to have that  $$ \begin{align*} L^2|k\rangle&amp;=L_z^2|k\rangle+L_-L_+|k\rangle+L_z|k\rangle\\ &amp;=k^2|k\rangle+L_-L_+|k+1\rangle+k|k\rangle\\ &amp;=k^2|k\rangle+|k\rangle+k|k\rangle\\ &amp;=(k^2+k+1)|k\rangle \end{align*} $$  which shows that $|k\rangle$ does not have eigenvalue $m(m+1)$ but $k^2+k+1$ for $k&lt;m$. Covering estate tax on US assets for non-resident alien I am a non-resident alien holding a brokerage account in the USA but residing outside the USA. My country does not have an estate tax treaty with the USA. So my estate is liable for a significant estate tax up to 40%. Is there any way to avoid or to cover this tax? I thought of buying term insurance for myself, but I am not sure whether US companies will sell term insurance to a non-resident. I want to buy insurance from a US company because I want the death benefit to be in USD. Can someone suggest as to what the best way to approach this issue is? XGBoost Loss function Approximation With Taylor Expansion As an example, take the objective function of the XGBoost model on the $t$'th iteration:  $$\mathcal{L}^{(t)}=\sum_{i=1}^n\ell(y_i,\hat{y}_i^{(t-1)}+f_t(\mathbf{x}_i))+\Omega(f_t)$$  where $\ell$ is the loss function, $f_t$ is the $t$'th tree output and $\Omega$ is the regularization. One of the (many) key steps for fast calculation is the approximation:  $$\mathcal{L}^{(t)}\approx \sum_{i=1}^n\ell(y_i,\hat{y}_i^{(t-1)})+g_tf_t(\mathbf{x}_i)+\frac{1}{2}h_if_t^2(\mathbf{x}_i)+\Omega(f_t),$$  where $g_i$ and $h_i$ are the first and second derivatives of the loss function.   What I'm asking for is convincing arguments to demystify why the above approximation works:  1) How does XGBoost with the above approximation compare to XGBoost with the full objective function? What potentially interesting, higher-order behavior is lost in the approximation?  2) It's a bit hard to visualize (and depends on the loss function) but, if the loss function has a large cubic component, then the approximation will likely fail. How is it that this doesn't cause problems for XGBoost?