I have a device that says it takes a 23A, 12V battery. I ordered a new battery and was mistakenly sent one with 27A and 12V - same voltage, higher current. Is it safe to use this battery in the device, or will it break things? Apologies for what must seem like a noob question; I'm not an electronics person. I have found  but it talks about capacity instead, and I'm not 100% sure whether that changes the answer or not.
Power supplies are available in a wide range of voltage and current ratings.  If I have a device that has specific voltage and current ratings, how do those relate to the power ratings I need to specify?  What if I don't know the device's specs, but am replacing a previous power supply with particular ratings?  Is it OK to go lower voltage, or should it always be higher?  What about current?  I don't want a 10 A supply to damage my 1 A device.
How do I get the full url of the page I am on in C# For the past couple of weeks, a process identified as usernoted appeared to "take over" my machine after a few hours of use, eating over 99% of available CPU.  Force quitting the process doesn't help; only a system restart puts usernoted to sleep for a while.  What is this process and how do I get it under control?  I am running OS X 10.10.5 (build 14F1021). HTTP request parameters are not available by request.getAttribute() How can I make content disappear when a user logs in? I am working in Wordpress, and I would like to make certain elements disappear once a user logs in. How can I do this?  I have social icons on my page that I positioned to the center of my menu bar at the top of my website.  those icons are generated by a plugin  that is what i want to disappear My Ubuntu 16.04 keeps disconnecting from the Wi-Fi (eduroam). Why? double perpendicular symbol (for independence) I found from  that I could use the independence symbol:     \newcommand\independent{\protect\mathpalette{\protect\independenT}{\perp}} \def\independenT#1#2{\mathrel{\rlap{$#1#2$}\mkern2mu{#1#2}}}    I was wondering how this works. Can anybody explain? I don't know the commands mathpalette, rlap, and mkern2mu. Will my device work with Ubuntu? Is it possible to detect a virus with taskmanager? If I would have a running virus on my system, would I be able to see the process in taskmanager? I mean, would it be possible for a running virus to circumvent the taskmanager so the process doesn't appear in the tasklist of windows7?  Or in other words. If I really now all the processes in taskmanager to be secure, I also know that my PC is clean? Constructing primitive cell using information from ChemicalData Prove that $\nabla_{\mathrm X} \mbox{tr} (\mathrm A \mathrm X^{-1} \mathrm B) = - \mathrm X^{-\top} \mathrm A^\top \mathrm B^\top \mathrm X^{-\top}$ Prove that $$\nabla_{\mathrm X} \mbox{tr} (\mathrm A \mathrm X^{-1} \mathrm B) = - \mathrm X^{-\top} \mathrm A^\top \mathrm B^\top \mathrm X^{-\top}$$   My proof is below. I am interested in other proofs.    My proof  Let   $$f (\mathrm X) := \mbox{tr} (\mathrm A \mathrm X^{-1} \mathrm B)$$  Hence,  $$\begin{array}{rl} f (\mathrm X + h \mathrm V) &amp;= \mbox{tr} (\mathrm A (\mathrm X + h \mathrm V)^{-1} \mathrm B)\\ &amp;= \mbox{tr} (\mathrm A (\mathrm X ( \mathrm I + h \mathrm X^{-1} \mathrm V))^{-1} \mathrm B)\\ &amp;= \mbox{tr} (\mathrm A ( \mathrm I + h \mathrm X^{-1} \mathrm V)^{-1} \mathrm X^{-1} \mathrm B)\\ &amp;= \mbox{tr} (\mathrm A ( \mathrm I - h \mathrm X^{-1} \mathrm V + O (h^2)) \mathrm X^{-1} \mathrm B)\\ &amp;= \mbox{tr} (\mathrm A \mathrm X^{-1} \mathrm B) - h \, \mbox{tr} ( \mathrm A \mathrm X^{-1} \mathrm V \mathrm X^{-1} \mathrm B) + O (h^2)\\ &amp;= f (\mathrm X) - h \, \mbox{tr} ( \mathrm X^{-1} \mathrm B \mathrm A \mathrm X^{-1} \mathrm V ) + O (h^2)\end{array}$$  Thus, the directional derivative of $f$ in the direction of $\mathrm V$ at $\mathrm X$ is  $$D_{\mathrm V} f (\mathrm X) = - \mbox{tr} ( \mathrm X^{-1} \mathrm B \mathrm A \mathrm X^{-1} \mathrm V ) = - \mbox{tr} ( (\mathrm X^{-\top} \mathrm A^\top \mathrm B^\top \mathrm X^{-\top})^\top \mathrm V ) = - \langle \mathrm X^{-\top} \mathrm A^\top \mathrm B^\top \mathrm X^{-\top}, \mathrm V \rangle$$  and, lastly,  $$\nabla_{\mathrm X} \mbox{tr} (\mathrm A \mathrm X^{-1} \mathrm B) = - \mathrm X^{-\top} \mathrm A^\top \mathrm B^\top \mathrm X^{-\top}$$ More section headings? I am a novice in LaTeX and I have one question.  Can someone tell me what if you want more heading's in LaTeX. Like 5 or 10 or even 15. Is there a package for that? Does option "-h" for "ls" display size in MB or MiB and is it consistent over Unix-based systems? One of the topics that seems to come up regularly on mailing lists and online discussions is the merits (or lack thereof) of doing a Computer Science Degree. An argument that seems to come up time and again for the negative party is that they have been coding for some number of years and they have never used recursion.  So the question is:   What is recursion? When would I use recursion? Why don't people use recursion? I read on the wiki that people will move in under the following conditions:   You do something to please them An empty house is available with a light source, table, and chair (also with walls).   I have a house which is about 7x8, then a roof space above that; about half the area. I could put furniture up there too, but will anyone move in? I'm writing up some notes that will be displayed on an overhead projector. The standard time-derivative \dot{x} produces a dot that is hard to see. Does anyone know of a package or have a macro that produces a (nice looking) larger dot? Similarly with \ddot{x}.  At the moment, I've been supplied with some ugly code that produces an ugly output:  \def\dt#1{{\buildrel  {\hbox{\LARGE . }} \over {#1}}}    % dot-over  \def\ddt#1{{\buildrel {\hbox{\LARGE ..}} \over {#1}}}    % double dot How long does the Truffle take to move in after building the mushroom biome? Wifi not working (Intel) on HP Spectre x360 13 Hyperref warning - Token not allowed in a PDF string What is the module/method used to get the current time? When a lattice is a lattice of open sets of some topological space? When a lattice $(L,\leqslant)$ is a lattice of open (or closed) sets of some topological space $(X,\tau)$? Which conditions have to be satisfied? We may assume that $X$ is $T_1$.