Could it be possible to contain an artificial singularity?

Question: Or would it just suck in whatever was attempting to contain it? I for the life of me can't figure out an explanation for it. Could we even create a singularity in the lab or would it be too dangerous?
Comment: I'm voting to close this question as off-topic because this is a [Physics](https://physics.stackexchange.com/) question.
Comment: It is not recommended to accept an answer before 24 hours because WB.SE has participants all over the world and people tend to lose interest in a question when they see it's been "solved."  You could lose out on many very insightful answers.
Answer: Believe it or not, but depending on the size of your singularity, the real issue might be sustaining it, not containing it. Hawking radiation tells us that black holes will dissipate slowly, and once they reach a critical size, will dissipate faster, especially if not being 'fed' with more mass.
This is not to say that they wouldn't be dangerous. The problem with containing an artificial singularity is that we just don't understand gravity enough to prevent the gravitational influence of the singularity from 'leaking' out of the containment system, whatever that would look like. That's assuming that the mass of a black hole alone without gravity doesn't cause other issues, say with our planetary momentum. It's not as simple as a powerful magnetic field (like in Romulan Warbirds) because we haven't integrated EM field theory with gravity yet.
When Maxwell integrated the theories of electricity and magnetism, it led to a massive growth in technology that hadn't been possible previously. Physicists are currently trying to integrate EM theory with weak nuclear forces. That would lead to another massive growth in our technological capability and understanding of the universe. Next would likely come Strong nuclear forces, and Gravity is likely going to be the last fundamental force to be integrated into a Unified Theory of the universe, primarily because it's so exotic by comparison to the others.
Until then, I'd be giving the creation of black holes a bit of a miss. They're just too dangerous and we don't fully understand them, even though we know a lot more than we used to.
Comment: No, but if the physics book gets thick enough, we can do more of the possible...
Comment: Not to add too much fuel to this particular fire, but if I remember my physics classes correctly, the only force strong enough to deflect the path of a photon without passing it through one or more changes of medium is gravity.  Star Trek ignored this when they decided that a magnetic field could contain a singularity as it means a magnetic field strong enough to deflect light.  It's a handful of illogical logic, but that pretty much means you need the power of the singularity to power the magnetic field that's strong enough to contain the singularity, leaving nothing for anything else.
Comment: 'It's not as simple as a powerful magnetic field (like in Romulan Warbirds) because we haven't integrated EM field theory with gravity yet.' Since we don't know the theory, it is not possible? The only things that are possible are the things we have a theory for?
Comment: @Justin, not necessarily. it's not possible **today** but that doesn't mean that we don't expect it to be possible in the future. Maxwell showed us that at least 2 of the 5 fundamental forces of the universe could be integrated and that in turn leads us to believe that it's possible to integrate them all. If this is the case, it's a matter of discovering the how. Another way to state this is that we haven't proven it impossible yet, so the possibility of such a thing has yet to be determined.
Comment: So if the physics book gets thick enough, anything is possible?
Comment: Or we can do more without worrying that it might be impossible to do?
Comment: String Theory is making the physics text book very thick indeed. That doesn't make anything more or less possible, it just means we THINK more and more things are more or less possible.
Comment: Probably a topic for a thread of its own, perhaps even in Philosophy. But, to explain my thoughts; manipulating Gravity may be possible, may be impossible. We don't know. Even if we think we know (like you say), a deeper understanding may change that perspective. We currently 'know' that time travel is impossible under the laws of relativity, but that doesn't mean a deeper understanding won't change that. Alternatively, we know powering a lightbulb with electricity is possible, and we've done it. String theory attempts to explain the universe, not solve an engineering problem for us.
Comment: Ha! indeed, that is probably the case, especially with our current understanding. That said, integrating electricity and magnetism led to developments like Radio which was a simple, cheap solution to communication which wasn't possible before. You're completely right that Star Trek conveniently forgets the energy needs of containment but that's not to say a cheaper (in terms of energy cost) gravitational containment system couldn't be generated in the future if Gravity was integrated into a unified theory. This is part of the journey of discovery we're on in physics today and in the future.
Comment: @TimB at least we can say for sure that if the Physics book gets thick enough it surpassess it's own Schwarzschild radius and collapses into a black hole.
Comment: @Doomfrost - Outstanding. :)
Answer: Let's take an example from piezoelectricity.  Piezoelectricity is the generation of electricity from pressure.  Simplistically, you stand on a piezoelectric plate and a light bulb turns on due to the elecricty generated by your mass applied to the plate.
Let's assume we can create some form of unobtainium that is both piezoelectric and indestructable.  An artificial singularity could be created and stuffed inside said globe.  Because our globe is perfectly round1 and we were able to place the singularity at precisely the center, the result is a singularity that is pulling in on the globe uniformly and therefore won't move.
The globe, of course, has an electrode connected to the inside of the globe passing though an equally indestructable but perfectly insulating insulator to a point ouside the globe.  A second electrode is connected to the outside of the sphere.  This gives us plus and minus voltage references.
Depending on how much the globe is allowed to compress, you now have an abundant source of electricty until the singularity dissipates (or until some idiot bumps the globe, allowing the singularity to go off-balance, sucking in the mass of the globe, the planet, and finally the moon, leaving the sun to become a binary star.  It's all very dramatic.  Let's call that idiot "Harold."  No offense to any Harolds reading this answer.)
A fundamental problem is keeping the singularity in one place.  Equally pulling is not as convenient as equally pushing.  Equally pushing means you could move the globe (within limits) and the singularity would stay in place... but it pulls.  Equally pulling means once you've figured out how to keep the two synchronously in place, you can't touch it.  We can come up with all kinds of handwavium solutions to drawing energy from the singularity—but now you have two real problems to overcome.  From the other answers: sustaining the singularity.  From mine: keeping it in place.

1 A good "family man" approaches a physicist with a "request" for a formula that will guarantee consistent wins at the racetrack.  The physicist, well motivated, works diligently and provides this good family man an answer.  "I guarantee it will work every time!" the physicist proudly (if nervously) proclaims.  "It haz betteh..." warns the man.  Later that day the now very angry family man returns and tells the physicist that the formula didn't work.  "I lost every bet!" the man screamed.  "I don't understand!" cried the physicist.  "It worked with the spherical horse!"
Answer: The important part about a singularity is that it has infinite density, not the amount of mass. According to wikipedia you can have a black hole at any size above the plank mass. Which means that it would exert the exact same amount of gravitational influence as any other mass of the same size. Like the other answer suggests, the main difficulty would be in sustaining it, not in keeping everything from being sucked in.
A visit to WolframAlpha using a statistic from the above wikipedia page shows us that in regular 3 dimensional gravity the minimum mass of a black hole would be 18 µg, which is certainly not about to suck the moon out of orbit. Furthermore, the Schwartzschild radius of this black hole is only 2.673×10^-35 meters. This would be pretty easy to maintain as long as we can keep it in a vacuum. Indeed, we're probably even safe outside a vacuum, as air molecules at STP [are more than 10 orders of magnitude farther apart than the Schwarzschild radius.
Additionally, I think it's important to think about conservation of mass and energy. If we're going to create a black hole big enough to pull the moon in to the earth, that energy has to come from somewhere, and that somewhere will have to be on earth for at least a short period. That energy will already cause the moon to be pulled in because, again, the only difference between a 5kg black hole and a 5kg bowling ball is that one is smaller in radius than the other. Outside the Schwartzschild radius there's really no physical difference.


Disable color and paging for mercurial

Question: New versions of mercurial will apply colors to the output of most commands and will pipe commands with long output to a pager. How do I restore the old behavior to not color output and never use a pager?
Comment: Thanks for your Q&A. Ran into the same thing, although I am not bothered by color. But the uncalled pagination reminded me of a very patronizing DVCS.
Answer: Add the following to your .hgrc:
[ui]
color = never
paginate = never

Answer: When working with commandline, you can also add parameters or options to your commands. This is however not permanent. The hg --help --verbose  reveals:
--color TYPE        when to colorize (boolean, always, auto, never, or debug)
--pager TYPE        when to paginate (boolean, always, auto, or never)
                    (default: auto)

So the next command disables your pager and does not show any colors:
hg incoming --pager never --color never

Disable color and paging for mercurial


imap command for save a message to draft

Question: i'm building a simple webMail and use imap protocol.
i want to add draft option to my webmail & need an imap command for save a message(which not completed composition) in draft folder?
could anybody help me?
Answer: Use the APPEND command. It doesn't matter if the message is incomplete. As long as it's a properly formatted email with a header and a body, you can add it to a folder.
APPEND is in fact the only command that exists in IMAP that allows you to add new content to the remote server, so you would use the same command to save the completed message to a "Sent" folder.
Answer: Example:
C: A003 APPEND saved-messages (\Seen) {310}
S: + Ready for literal data
C: Date: Mon, 7 Feb 1994 21:52:25 -0800 (PST)
C: From: Fred Foobar
C: Subject: afternoon meeting
C: To: email@example.com
C: Message-Id:
C: MIME-Version: 1.0
C: Content-Type: TEXT/PLAIN; CHARSET=US-ASCII
C:
C: Hello Joe, do you think we can meet at 3:30 tomorrow?
C:
S: A003 OK APPEND completed


Why does JWST make images of planets from solar system?

Question: NASA has already made images of planets from the solar system
before. So why is NASA/ESA making images of planets from  the solar system
by using the JWST instead of exploring unseen parts of universe?
Comment: Related: https://space.stackexchange.com/q/57492/38535
Answer: Quite simple: JWST is capable of making images with much better resolution in a different spectrum.
Land based telescopes cannot make such clear images due to the atmosphere being in the way. Additionally, the atmosphere blocks some significant parts of the (near) infrared spectrum, which is the spectrum in which the JWST is producing images (which are artificially coloured afterwards). Additionally, other space telescopes produce images with much lower resolutions and in different spectra, e.g. the Hubble in the visible spectrum and the Herschel Space Observatory in the far infrared and submillimetre spectrum.
Comment: Also, I believe there is an aspect of opportunism; if the telescope needs to slew past a planet in order to observe its next deep space target, why *not* take some pictures while it's doing so? Maybe that slew takes a little longer because of the pause, but the notion that we're just "wasting" JWST's time, as seems to be implied by the OP, isn't entirely accurate.
Comment: And layering on the IR data onto very well known subjects (local Planets) it quickly provides much important data for planetary researchers.  And since we have imaging of some from much closer by probes, comparing can help understand how JWST sees things as well.
Comment: @ToddWilcox, it's simple: it's been almost 33 years since Voyager II last took a picture of Neptune.  Things may have changed since then.
Comment: If you go make this answer 100% complete, you could also explain why the images taken by Voyagers I and II are not sufficient.
Comment: @GremlinWranger or from space by Hubble


how to setup irc domain on another server?

Question: like i have the site on one server but irc (the site uses) should be hosted on another hosting provider. i have domain set up for the site. should get another one for the irc hosting and do cname to it? what should i do?
Comment: Please move to ServerFault (and maybe fix up the wording)
Answer: An irc subdomain (irc.example.com) is common, but if you want a different domain, that is your choice.
You can't use "example.com" for both the web site and the ircd if you want them hosted on separate servers.


Is it secure to store a PHP crypt() result in the db?

Question: For example with blowfish it returns something like:
$2a$12$DEzG.CRsHpxpTOAHooQ.wuR6Xe9h6PxFPhOcOvf.lqDNw1TVYVnEO
That contains info about the type of hashing alg and it contains the salt. A lot of resources say to just store this value in the db and it will be secure. But couldn't someone just test a common list of passwords against these values to crack some of them?
Answer: The security of password hashing does not come from information being secret. You have already discarded the actual secret, namely the password that is the basis for the hash value. The remaining hash is simply a sort of fingerprint of this original data. The security comes from the fact that it is not possible to derive the original data from the hash. The only possibility is to try all possible passwords and see which produces the same hash. The security here comes from the fact that this is computationally very expensive and unlikely to succeed in a useful amount of time.
The salt is only introduced to prevent somebody from using an already precomputed set of known hashed passwords, forcing an attacker to actually rehash all possible passwords with the unique salt. The salt itself is not secret, neither is the hashing algorithm.
In short: yes, that value is absolutely safe to store in a database.
Answer: The hash generated by crypt() is specifically intended to be stored. No matter what your password hashing scheme is, if somebody gets hold of your database contents, they will be able to brute-force your passwords, and you don't have the option of not storing password hashes at all. The algorithms applied by crypt() are specifically selected because they take significant time to calculate the hash; this is not apparent when you only test one password, but brute-forcing thousands of passwords becomes impractically slow.
Comment: yes, i have to add some string to password to store ....
Answer:
But couldn't someone just test a common list of passwords against
  these values to crack some of them?

You could always do no matter how the passwords are stored. The crypt function does not prevent this, but it will make it really really slow. If a user uses a really common password (as 123456) no hashing algorithm in the world will protect him.
If you disallow those simple passwords and use a good hashing algorithm (that crypt() supply) you have done your best to protect the passwords.
Answer: If someone has access to your database then they would have access to the salt either way, since you should be using a different salt for every users password (which you most likely would store along in the database).
The point of the salt is so that rainbow tables don't work. The individual would have to re-hash every combination of password + salt in order to determine the password. You use a different salt on each password so he has to re-generate millions of hashes for each one.
Some more good information on crypt can be found here:
Why does PHP crypt() prepend the salt to the hash?


Password Stealing vs Account Hacking

Question: Which is more likely to occur, and by how much: getting your password stolen, or getting your account hacked by brute-force?
Comment: If you count db breaches as stolen, stolen, far and away more common.
Comment: device accounts? online accounts? service accounts?
Answer: This question is badly designed. Obviously if you're using a stupid/overly short pass like "qwerty" expect to be brute-forced or guessed. Standard practice among hackers includes a list of the most common ones used and they run through that list before alphabetic brute force.
If the end-user isn't a complete idiot, brute-force and guessing become increasingly unlikely and the major threats are:
Client-side keylogger malware, usually downloaded by a malicious script attached to a website or email attachment or included as a trojan in a larger program.
Server-side shenanigans. Even if you're 100% perfect at protecting your computers, there's always the chance that someone at the server end failed to patch vulnerable software (**cough cough* Equifax **cough*), downloaded a keylogger/malware that steals server DB admin logins, or clicked on a phishing email and compromised the network.
Answer: Your request isn't very precise, so it's not clear what kind of data will best answer your question.  However, a good place for you to look would be on PasswordResearch.com, where many studies pertaining to passwords and breaches have taken place.  This link will take you to a list of statistics about criminal activity involving authentication.
Answer: It depends entirely on your password and/or how likely you are to be targeted.  If you use a weak password that is easily susceptible to guessing, you are likely to be compromised in this way as basic dictionary attacks are run at a low level constantly.
If, however, you use a secure, long password, it rapidly becomes impractical to brute force the password directly.  Password theft, however, is not the only way to compromise an account.  It is possible that accounts may be compromised without the password directly via a number of different types of attacks, so password theft isn't the only problem other than brute force that has to be worried about.
Attacks like cross site scripting can attempt to make legitimate users take illegitimate actions or attackers may simply attempt to hijack the legitimate session of a user.  These don't require access to the password to make use of the account.
Good password selection will prevent brute forcing, but password theft isn't the only threat to worry about.  It also is important to realize that bulk data breaches regularly compromise either direct passwords or password hashes (sometimes weak hashes) so it's really important to use long and unique passwords for your accounts.

Password Stealing vs Account Hacking


2 xbox 360s in one house

Question: My brother and I both want to be able to play on xbox live at the same time on the same game and different games do I need 2 gold memberships? Is there anything else I need to take into consideration?
Comment: You need 2 separate gold memberships and you're good to go. Something else you might want to take into consideration is your internet speed. I lived in a house with 4 other people and we had to get a faster internet connection because some of us experienced lag issues when we were all playing at once.
Comment: @Phaelin you need two copies of the game. Installing to the hard drive doesn't let you play without the disk in.
Comment: Can anyone clarify if you need two copies of the same game in order for the brothers to play the same game simultaneously? If one installs it to the 360, for example, can the other play it off the disk? It has been a while since I last tried that so I don't remember, but thought it would be a useful add-on for the best answer.
Comment: Note that in some games, like Halo ones, you can play online in the same console with only one Gold account. The other player has to play with a guest profile
Answer: Yes, to be able to play online multiplayer at the same time on separate consoles, you will need two separate accounts, each with an Xbox Live Gold membership.

2 xbox 360s in one house


How to sell codes, like games codes on magento?

Question: How can I sell virtual codes, like for steam and origin games on magento?
Comment: Just create virtual or downloadable product with key....virtual will be sent on email or downloadable save as PDF of something :)
Comment: @theStreets93 It would be great, if you can put this is an answer to this question.
Answer: Just create virtual or downloadable product with key....virtual will be sent on email or downloadable save as PDF or something :)
More about virtual here and downloadable here.
Good luck! :)
Answer: I would say that this will depend if the codes you are selling are unique.
If you want to sell a virtual code, and it's exactly the same code for each person purchasing it, then you could use a downloadable product to accomplish this.  The downloadable product would have a PDF or text file that would contain the code.
That could be accomplished without any modification to Magento.
If you wish to sell unique codes - so that each user purchasing a product then gets a unique code - you would have to create an extension that will handle this added functionality.
You could either have the system generate the keys on the fly as each product is purchased, or you can have a big list of unused keys that were generated elsewhere but stored in a mySQL table in the Magento system.
The advantage of generating the keys on the fly is that you aren't storing a big database of keys that someone could potentially grab; you're also less likely to run out if you have a lot of people purchase them.
The advantage of having a table full of keys that are generated elsewhere: you don't have the encyryption systems on the server that are used to generate the keys.
Either way, you'll need to use an extension to manage this functionality, as it doesn't exist in the default Magento system.
I hope this helps!


Are my tyres fully worn?

Question:
These are https://www.donnellycycling.com/products/strada-lgg-700-x-28-60-tpi-wire-bead-clincher?variant=1590231400466
The treads are still visible...but the middle section looks a bit worn to me. I'm not sure if there's any tread wear indicators built into this tyre. Anyone think I should change?
Comment: FWIW I rode 4,100 miles. Only once or twice on rough surfaces, and the rest of the time on pretty decent road surfaces.
Comment: Another solution is to remember when you fitted them and work out how far you've ridden.  Barring cut/damage, a road tyre should do at least 5000 km.
Answer: Good enough to ride on.
The surface is still smooth (no cuts or the internals shining through) - I can still see rubber. I personally tend to change mine when they have too many cuts, less material punctures easier and objects may punch through existing holes. That's usually way before they are totally worn down, for example if I have to change a tube at home (losing pressure, valve issues), I can put a fresh tyre on the front and relegate it to the back if still looks good.
Answer: If utterly maximizing your tire lifespan is very important to you, then you can ride until you see casing threads in one spot. I would not suggest that most people do this. Generally, with worn rear tires, when we look at them, they become flat at the top. Riders may feel like they get more punctures on worn tires - I had a couple tires where the tread wear indicators were not worn off, but I felt like I was getting more punctures and I elected to change the tires. You do get more punctures because there is progressively less and less material, so a shard of glass has less distance to travel before hitting the tube. Both of these criteria are admittedly subjective. I don't see a way around it.
For gravel tires, most of which have treads, wearing the tread off the center of the tire is an indicator of worn out tires. Here, the model doesn't appear to have had tread in the center. Even if it did, I agree that it's still usable.
Answer: There's still some life left in those tires.
You replace tires when you see the cords from below the tread, and if you do, then you're in a hurry, you really need to replace the tire fast. I don't see any cords visible in your photograph of your tire. Road tires do not require a tread pattern, in fact slick tires work the best.
Answer: Some road tyres are having two little holes in the running rubber. They serve only one purpose - to show you the actual depth of the rubber one still have in hand. When the hole(s) disappear, your tyre is to thin and the manufacturer suggests you replacing it.
Other option how to check the status is deflating the tyre and squeezing it form the sides. If it is very easy to fold the tyre or when it folds inwards - in other words it the tyre walls support the tyre more than the runing patch - then it is time to change the tyre.
The thin rubber does not affect the riding comfort much. On the dry tarmac missing thread does not harm the handling, it is better, actually. On other surfaces (wet tarmac, sand, mud,...) the thread is critical for the grip.
In this case, the thinner tyre is just more prone to punctures.

Are my tyres fully worn?


Maintenance as my Derailleur are squeaking due to the everyday use and carelessness shown while changing gears while the cycle is static

Question: What extra steps should I take to extend the life of the Derailleur gears on my Btwin Rockrider 340 besides oiling them ?
Comment: Can you explain more clearly what you mean? Where are you oiling specifically? How do you mean, changing gears while the cycle is static? What component are you worried about damaging?
Answer: My guess is that your chain is squeaking as it passes through the derailleur pulleys because it is dry.
Cleaning, lubrication and correct adjustment are the keys to long life with a bicycle.

If the chain is dry and not dirty all you need is some bicycle chain appropriate lubricant (lots of choices)
If the chain is dirty and dry you can clean the chain on the bike (a quick Google of "bicycle chain lubrication" will give you lots of information)
If you lubricate the chain and it is the derailleur squeaking use a bike appropriate lubricant on the pulleys and the pivot points on the derailleur.

Changing gears while the bike is not moving may cause the cables to stretch and effect shifting quality, but it's unlikely to cause the derailleur to squeak.


Does an ellipse or circle have greater circumference?

Question: If an ellipse has semi-major axis length a, and a circle has radius a, and you walked along their boundary, which one would be longer? A circle's circumference is calculated using $2\pi r$, but I don't know the equivalent for an ellipse. Probably involves integration. Is there a general rule or will it vary from case to case?
Comment: @micapps: The semi-minor axis is, by definition, smaller than the semi-major axis. So the circumference of the ellipse will always be shorter than the circumference of the circle.
Comment: Not to come off as rude, but have you tried Googling "perimeter of ellipse"? Haitorically, this was a very important question, and the solution was one of the major early successes of calculus.
Comment: What is the semi-minor axis? You can find much information in the Wikipedia article on Ellipses: https://en.wikipedia.org/wiki/Ellipse. In particular, look under "circumference".
Are you looking just to compare the circumference of a circle with that of an ellipse or to calculate exactly?
Comment: @Micapps In particular, I wonder whether a planet moving in an elliptical orbit would go further than one moving in a circular orbit. I'm not really looking to calculate exactly, just make a general comparison.
Comment: @Karacoreable It still seems you're missing information. What is the semi-minor axis? If it is very small the perimiter will be less than the circle and if it is large it will be larger.
Comment: @TonyK Good point.
Answer: If the semimajor axis of the ellipse is identical to the radius of the circle, then the perimeter of the ellipse is smaller. One way to see this is by continuously increasing the semiminor axis to match that radius as well. This will stretch your ellipse to a circle, and that stretching will only make things (lengths as well as areas) larger, never smaller.
Actually computing the perimeter of an ellipse involves elliptic integrals, which is the reason why there is no direct analogon to the simple $2\pi r$ you have for circles.

I wonder whether a planet moving in an elliptical orbit would go further than one moving in a circular orbit.

If that's what you are after, then likely the perimeter is of little interest. You should ask about this explicitely (but not in this question here, and only after checking existing answers). If you do so, make sure to be precise as to what you fix in your comparison. Is it the energy of the planet, or the perihelion distance, or the orbit period, or whatever.


How to find whether the electric field between capacitor plates is above or below the electrical breakdown limit of the insulator between the plates?

Question: Let's say the two plates of a capacitor have charges $q_1$ and $q_2$. The separation between these plates is $d$. I know that I can calculate the electric field by dividing the voltage that is applied to the capacitor by the separation distance and comparing the answer with the electrical breakdown limit to see whether it is above or below the electrical breakdown limit. However, what should I do if I know the charges on the plates rather than the voltage? Sould I use $E=kq/d^2$ where d is the separation distance? If I should use it then which q should I use in the equation, $q_1$ or $q_2$? Because the electric fields calculated with $q_1$ and $q_2$ are different which makes me confused.
Comment: Are you really asking about two capacitors, or are you just getting the terminology confused?  One *capacitor* consists of two *conductors* separated by a dielectric.  Are you really asking about two capacitors, in which case the question involves four conductors?  Or are you really meaning to ask about one capacitor, whose two conductors hold charges of $q_1$ and $q_2$?
Comment: @RedAct I'm sorry I meant one capacitor which contains 2 conductors.
Comment: So that others can understand your question, I took the liberty of tweaking your question so that it says what you intended it to mean.
Comment: It's really not that complicated as you think. If you know the charges on the plates, that's enough. Find the field [http://hyperphysics.phy-astr.gsu.edu/hbase/electric/elesht.html] due to each plate induvidually at a point as a function of the distance from one of them, then vectorially add them to get the net field.
Answer: The total amount of charge on the two plates is 0, i.e. $q_1=-q_2$, in the case of a plate capacitor, the field is twice that of a field produced by an infinite charged plate, so $E=\frac{q}{A\epsilon}$ where q is the charge on the plate, A is the area of the plate, and $\epsilon$ the relative dielectric constant of the material between the plates.


Is it okay to run regtest for dev purposes while simultaneously running a node on mainnet (bitcoind)?

Question: Hope it won't mess anything up on my mainnet node.
Answer: As long as your nodes are running on separate ports and using separate data directories, you should have no issues running multiple networks.
Note that you may run into resource issues, especially with regular spinning HDDs, if both networks have high requirements for disk writes and reads at any point.


how to create a new file in an immutable directory

Question: I have changed the directory attribute immutable by chattr +i /testdir; but I need to create files in that directory.
Or is there any way that nobody can delete the directory but the owner can still write in that directory?
Answer: The way to get what you need is:
chattr +a /testdir
Set the permissions on the directory itself so that only the owner has write permissions.
The a switch makes it so that the files can be created and modified inside but not deleted.
The manpage for chattr only says what a does for files but it does indeed do the above when used on a directory as I found out myself when searching for a way to do the same.
Comment: Folder will be append-only, meaning that once you create a file in it, you can never delete it. Only solutions around this are (a) either to remove the `a` attribute before deleting files, or (b) use Romeo's solution and make a 2-level directory tree, with the first directory's permissions set to `r-xr-xr-x`. It's a pity that there's no "un-removable directory" flag that prevents a folder from being removed, while permitting to alter/remove its content.
Answer: The command
chattr -i /testdir

will remove this flag. Then you create the new file and again
chattr +i /testdir

you should set only r and x of parent directory for group and other to prevent removing the directory
Answer: The immutable attribute set on a directory only affects this directory and its immediate (e.g., 1st level) content. Not the content of a sub-directory.
So, if you only need to add files to this directory, without ever having to modify or to delete files from it; then using the a attribute like Nasir Riley showed is the way to go.
On the other hand, if you want to be able to have a full control of the directory, while preventing the directory from being renamed/deleted, then you could use a subfolder, and make only the upper-level folder immutable, for example :
$ mkdir d1
$ mkdir d1/d2
$ sudo chattr +i d1

You can then verify that you have full control over d1/d2 :
$ touch d1/d2/f1
$ mv d1/d2/f1 d1/d2/f2
$ rm d1/d2/f2

While at the same time the d1 folder is immutable :
$ sudo rm -rf d1/
rm: cannot remove 'd1/d2': Operation not permitted

$ sudo mv d1 d3
mv: cannot move 'd1' to 'd3': Operation not permitted


Gravitational acceleration

Question: 'What is difference between free fall acceleration g and gravitational acceleration a?***a is with subscript g.In my textbook it is written that "free fall acceleration = gravitational acceleration - centripetal acceleration." so i'm confused if there is any difference between these two?
Comment: Your original question attracted correct answers.  Rather than continuing to edit this question that already attracted correct answers to what you wrote: I would suggest reverting this question back to the original version. Then ask a whole new question where you put centripetal acceleration into the title and possibly in the tags as well and specifically state (in the new question) that you want to know about about "how the rotation of the earth and the acceleration due to gravity combine to make an effective inertial force" and feel free to use that exact phrase in the new question.
Comment: Oh, and even after you revert this one back to the original, the software should allow you to find this version from the edit log and get the source and then you can copy that to your new question. Your new question is probably going to be classified as homework, so read the policy on asking homework like questions.
Answer: In the second law of Newton appears the acceleration $a$. It refers to a generic acceleration due to any phenomenon. $g$ has the same role of $a$, but it refers specifically to the acceleration of gravity (free fall particular case) on the Earth. Usually we approximate $g$ to be constant $\left(9.81\, \mathrm{m}/\mathrm{s}^2\right)$, but in the real case the value of $g$ change at different altitudes (as mentioned by Edward Newgate).
Comment: Your textbook is considering a particular case: an object that is orbiting around the Earth. You have to decompose the motion in 2 singular motions: 1) the falling motion due to the gravitational force and 2) the circular motion. 1) is forced by the gravitational force and 2) is forced by the centripetal force. So the resulting motion is the sum of 2 motions. The total force is the sum of these 2 forces: F_total = F_gravitational - F_centripetal (these 2 forces lie on the same axe, but they are opposite). Forces are linear in acceleration, so the same relation is true for accelerations.
Comment: Here the total acceleration is called free fall acceleration, but this is only your textbook convention.
Answer: Newton devised a very good law of gravity (until Einstein came along) where the force between the two bodies is scaled by a very small number usually written as a capital G. It's a general law that applies to any two bodies. But if you plug in the mass of the earth, the mass of a test ball, and the distance between the center of earth and the test ball, then plug in the experimentally determined G you will deduce the force on that test object. Next if you plug the calculated force on the test object along with its mass into another of Newton's laws F=ma and solve for a you will get the acceleration that the ball will experience at earths surface due to gravity. Since it is known that the calculated acceleration is independent of mass (it pretty much comes out the same for all test balls unless you do something ridiculous like plug in the moon but then you've got a radius issue) they give it a special symbol little g and give you the approximation 9.8 some odd meters per second per second.
Edit: In the text book images above a seems to be the usual g and g is shown to include other accelerations. Another way you could complicate the equation is to consider the acceleration imposed by various other planets on the test ball. Also give it a charge and imagine some other charges pulling it in various other directions. Then you'd get an equation like mg=ma+fifty other things... But for almost all practical purposes g=a so you want to look at F=mg only. Here's an example of a situation that breaks that rule: in the equation above the extra term subtracts from ma resulting in smaller mg (weight) when you're lifting things it's easier to lift smaller dumb bells than larger ones right? Well in the space rocket industry easier equates to less fuel. which means less costs. So to maximize that second term they tend to build space centers nearer to the equator.
Answer: I think you are confused between gravitational CONSTANT g, and gravitational acceleration a which can be thought of as a VARIABLE.
Gravitation acceleration g is around 9.81m/s^2 near sea level. But as you go higher the gravitational acceleration is no longer g, but another number, let's say a. a is a more generic gravitational acceleration that is not necessarily g.
Also, a is not only gravitational acceleration, but can be acceleration due to other phenomena (ex. Tension force).
Comment: No, $g$ changes depending on the planet or the reference frame.  It is called gravitational field strength or gravitational acceleration. It is NOT limited to the surface of the Earth.

Gravitational acceleration


What is IQ Data?

Question: I have no background in telecommunication. Could anyone please explain to me what is the IQ data in telecommunication? It will be best to explain it with some basic analogies. Many thanks!!
Comment: Have a look at this discussion http://dsp.stackexchange.com/questions/7612/i-and-q-channels/7613#7613. Also understand what complex baseband representation of passband signal is. That will help you understand it.
Comment: I have a follow up question really. I used a signal analyzer to get IQ sample data from a blue tooth device. The IQ data received is in the form of a .MAT file and I examined the file contents and see an + ibn samples where a, b are constants, n is the sample number and the format is a complex number. I was told the real part is the I and the imaginary part is the Q. Are these samples received baseband I Q data? I am trying to determine the carrier frequency offset. I was trying to determine the frequency of the signal. I felt I could measure the phase difference between samples per time. Howe
Comment: @PeterE Please [ask a new question!](https://dsp.stackexchange.com/questions/ask) You have "answered" the original question with a non-answer.
Answer: Here is a good article from National Instruments. In general, we ask on this site that you put in more effort into your question, e.g. links to articles that you've already looked at and things you haven't understood. Otherwise, you'll simply get an answer which is the first link you get from Google when typing in your question.
In a nutshell, I/Q takes advantage of sine and cosine signals being mathematically orthogonal to each other, and therefore separable with very little amount of effort. This means that with appropriate care taken, you can modulate one signal with a sine wave, another one with a cosine wave (they are simply delayed versions of each other), and still be able to separate these two signals at the receiver even though their frequency spectrum overlaps.
If this is either completely over your head, or completely obvious to you, edit your question with clarifications of how much you understand. Otherwise it's impossible to give you the exact answer you're looking for.
Answer: A simple answer is that I/Q are the real and imaginary components of the complex-valued transmitted baseband signal.   In communication systems "I/Q data" usually refers to the real (I) and imaginary (Q) samples of the constellation for the modulation type used. There are usually a lot of I/Q "samples" (rather than "data") that happen during interim processing.
Answer: I and Q signal concept is relatively complex topic to explain without signal background, you first need a basic knowledge about Passband and Baseband real and complex signals. if you are familiar whith these topics, you can jump to the last paragraph.
In short signals are any representations of real life quantitative parameter value versus to another variable mostly "time", i.e. values of room temperature in every hour is a signal.
Any signal with real values is type of real signal, e.g. all of physical signals are real, and signals which include imaginary values are complex signal. complex signals are widely used when processing real signals.
Another topic here is baseband and passband signal. first you should know every signal based on it's nature occupies specific frequencies in its spectrum. when a signal only occupies low frequencies (near or include zero) it called baseband signal. most of the signals in nature are baseband.
and when a signal occupies higher frequencies far enough from zero (dc), they called passband, in telecommunication passband signals are created from baseband signal (modulating) when trying to send data through a medium which doesn't works well on baseband signals, such as Air, i.e GSM, UMTS signals are passband.
In telecommunication theory and applications, I and Q signals are respectively Inphase and Quadrature component of a passband (or aka RF/IF) signal, which both of them perfectly represent the passband/RF/IF signal. I/Q signals both are in baseband and easy to work when modulating, demodulating, manipulating or examining the passband/RF/IF signal.
Welcome to the complexity :))

What is IQ Data?


What files do I need to recover MySQL databases from Ubuntu?

Question: I have a now non-bootable install of Ubuntu.  What files do I need to copy to backup all of the MySQL databases (including database users and permissions)?
Answer: Since you don't have any dumps, you want the files in <code>/var/lib/mysql/<dbname></code>.  Since the system won't boot, I would boot with a live cd a mount the hard drive read only.
It should be okay if the DB was not running when when it shut down.  If it was running, there might be some corruption.  There might also be some file system corruption since it won't boot. Here is a post on recovering databases when they are in a unclean state.
In the future, the proper way to backup databases (if you don't use special software for it) is to create a dump of the database, and then back up those dumps.
Comment: The link is broken for "Here is a post "
Answer: The database dumps.
You might be able to copy the data directory to another machine and stand up mysql there.  But you will have better luck with actual dumps.
man mysqldump.
Comment: If it wasn't clear, I can't boot the OS that MySQL is on. I'm guessing that mysqldump wouldn't be able to help me without a running server.
Comment: Yeah, that's why I mentioned the data directory that Kyle expanded on.


Can I add to a pre-made rig?

Question: Is it possible to add to a pre-existing rig? I'd like to add a facial rig to either the Unreal Mannequin or the Mixamo rig. But when I set it up and parent the new bones to the mesh the rig stays put and the mesh scales up by 100. Is there something simple I'm missing or is this just not possible to do this?
Answer: To answer my own question...when selecting the parent instead of "With Empty Groups" or "With Automatic Weights", Set Parent To "Object (Keep Transform)". Then in Pose Mode under the Bone Properties (little green bone) at the top you can see what the new bones are called. When weight painting you'll just have to add your own vertex groups named what each of the new bones are called. Then do manual weight painting. Kinda tedious but it gets the job done :)

Can I add to a pre-made rig?


How to select a specific color in Photoshop CS2?

Question: I'm trying to reduce colors from million to 7 exact colors. It's a fabric design, so I want to separate greens from the other colors. However, when I want to pick greens, other different colored pixels that belong to motifs are getting included in the selection area.
Comment: Is Photoshop CS2 not a little bit old?
Comment: @Kurt If that's what the OP has to work with...
Comment: Have you tried using photoshop's "select color range" tool?
Comment: yes i have tried it, but it didn't work at all. my goal is to reduce colors by their own values. for example; i want to obtain only greens in leaf motifs. but when i reduce the color, i see some greens, blues, and yellows in a leaf. because i also used that colors in the whole design.
Comment: @Kurt You are right, but the company I work for has only this version.
Answer: The good news.... yes, it can be done in practically any version of Photoshop.
The bad news.... It can be a difficult task depending upon the artwork. In addition, to requiring some experience with creating selections and masks.
Trying to remember CS2: Select > Color Range... may possibly get a good starting selection, as mentioned in the comments above.
Quick Mask would allow you to "paint" areas you want to be part of a selection.
You could use the Channels Panel combined with tools such as the Magic Wand to get a selection.
And of course, there's the Magic Wand tool or Pen tool or Lasso tool to draw a selection.
There are a great many methods to create a selection. Essentially just use whatever is easiest for you to get a good starting selection. No method is just going to be "perfect" with a click. What you describe "other different colored pixels get selected" is due to anti-aliasing. This is going to happen with practically any selection method if the artwork has anti-aliasing. There's no way to easily or automatically get around anti-aliasing in most cases.
After a selection is created, it's a matter of refinement. Once you have a selection, turn it into a layer mask. Once you have a layer mask, you can then go in and manually use a brush to paint away any anti-aliasing pixels you do not want as part of the selection.
Basically the procedure would be the same as removing a background from an image but in this case you'd be removing everything except the color you want to retain.
Seeing a screen shot of specific artwork may yield more detailed instructions. However, in most case the above steps are pretty much the same.


Why did Ya'akov work for Lavan for so long?

Question: I'm having a bit of trouble understanding Or Hachaim's explanation on Breishit 29:18. Usually Jewish slaves work for only 6 years. Yet, Ya'akov offers to work for Lavan for 7 years as payment for marrying Rachel. Ohr Hachaim says that there is a "secret" behind the number 7. Despite that, esp. if Ya'akov had already suspected that Lavan was not trustworthy, why did he offer his work for so many years? (I may be missing something in Ohr Hachaim's explanation that would answer this.)
Comment: @chachamNisan Take it up with the Ohr HaChaim, not the OP. Only for the last six years was he a Po'el, anyway. The Ohr HaChaim seems to base this on the passuk using the term עבד rather than פעל or even שכר.
Answer:
"…and the (seven years) seemed to him only a few days, because of the
  love he had for her." Genesis 29:20

Abraham Joshua Heschel wrote:

Should not the reverse be true, i.e. that a day should seem to Jacob
  like years because of his love for Rachel?
The wording of this passage is meant to convey to us the profound
  spiritual nature of the love that bound Jacob and Rachel to one
  another. In a love based on physical desire, the lovers want the time
  of separation to pass quickly so that each day they are apart seems to
  them like a year.
But in a spiritual love, devoid of self-seeking desire, such as that
  of Jacob and Rachel, the lovers do not care whether the object of
  their affection is near or far away. The spiritual love between Jacob
  and Rachel had already found fulfillment, and therefore, seven years
  seemed to Jacob only a few days.

Before we go into the main topic i.e

why Ya'akov enslaved himself for so long?

We need to understand more about his father-in-law "LABAN"
Laban is identified by the Rabbis with Beor, Balaam's father, and with Chushan-rishathaim (Judges iii. 8), the last name being interpreted as "perpetrator of two evils" (Sanh. 105a; comp. Targ. pseudo-Jonathan to Num. xxii. 5).
R. Joshua b. Levi, however, identifies Laban with Kemuel (Gen. xxii. 21), the latter name being interpreted as, "who stood up against God's people"
Laban is called also "the master of impostors" (ib. lxxv. 6). When he saw the bracelets on Rebekah's arms (Gen. xxiv. 30) he determined to kill Eliezer; but the latter, divining his intention, pronounced the Sacred Name, by which he caused camels to remain suspended in the air above the well. This and Eliezer's resemblance to Abraham made Laban believe that Eliezer was Abraham. Laban therefore invited him to enter the house (Midr. Abkir, in Yalḳ., Gen. 109; comp. Midr. Hagadah on Gen. xxiv. 23).
When Jacob had completed his seven years of service, Laban assembled his countrymen and consulted them as to the best means to retain him; "for," said he, "ye know that formerly we had a scarcity of water, and it is only through this righteous man that we are now blessed with an abundance of it." His countrymen advised him to substitute Leah for Rachel (Targ. pseudo-Jonathan and Yerushalmi to Gen. xxix. 22; Gen. R. lxx. 17).
Shows how Laban tricked Jacob into slavery and Jacob finding his way out.
Comment: Welcome to MY and thank you for your answer! Don't forget to [cite your sources](http://www.jewishencyclopedia.com/articles/9568-laban) if you use other authors' work!
Comment: Welcome to MiYodeya. Since MY is different from other sites you might be used to, see [here](https://judaism.meta.stackexchange.com/a/3887/11501) for a guide which might help understand the site. Great to have you learn with us!
Answer: 1.Answer by rabeinu Bachya. Rachel was 5 years old that time and could not become a mother if his children, so Yaakov offered Lavan 7 years of labor till she becomes 12.
2.Answer by Pardes Yosef. Rivka told Yaakov to stay in Haran "yamim ahadim". YAMIM is 1 year (based on parasha BEHAR "yamim tehe geulato") and AHADIM are SHABATOT (based on Midrash where Shabbat is called "yahid"), so basically Rivka told Yaakov to stay with Lavan 1 year of Shabbatot, i.e. 52 into 7 = 364 shabbatot and this is 7 years!
Answer: First, is your question about 7 years as opposed to 6 or in general, why so many years? Because I asked something similar - why not use his father's wealth to get away from the work altogether and nobody responded yet.
I don't know a clear answer, but I can only hint you, based on Baash"t and Ariz"l explanations on Yaakov's mission at Lavan. If you remember, he stole Eisov's Brochos, and therefore, Eisov's mission in this world. His original mission was a  Torah learner (Aseh Tov) but now he needed to be Ish Tzayd, to complete Eisov's mission of Sur meRah. This is the reason he went away to Lavan to Huzt laHaretz, the land of idolatry, instead of his father's bringing Rochel home to the Holy Land.
This is the reason he spent those long years at Lavan's residence Mamash as Lavan insisted, constantly fighting Lavan (Sur meRah) and going through all those tests and humiliations etc, instead of grabbing the grown-up daughters and running away back home.
I am sorry I'm really bad with sources, I simply don't remember who said that, and don't have time to search it up (source needed) but Eisov was one to father and establish the 12 Tribes, but now Yaakov took it all. Isn't it strange he realized he should have children at 84?
So the answer (according to Drush) is that that was his new mission he took from Eisov to cope with Lavan's evil 3 times 7 years, you probably know what those numbers stand for.
Sorry again for not bringing sources.
Comment: I understand a busy schedule. When you can, please provide some sources. it's difficult to understand the various allusions you mention in this answer without seeing at least one source / link to the original.
Comment: What exactly do you want to know?
Comment: Not sure, yet, actually. I have to re-read your answer! Counter-point to your stating " why not use his father's wealth to get away from the work altogether" - there'sa Midrash I thin cited by Rash"i that says that Elifaz, Esav's grandson fought with Ya'akov, and Ya'akov gave him all his wealth. It's a bit unclear of the timing of this event. However, see a related Rash"i on when Lavan first meets Ya'akov and hugs and kisses him to see if he has a diamond hidden in his mouth. Pparently, he didn't have anything at all, which is why he had to work. It's strange that at first, he works for free.
Comment: I have already addressed this Midrash. It does not help. Say Bill Gate's authentic son comes to you and says he was robbed, he asks you for a favor and offers to pay with his manual labor. Will you make him work or serve him for free and charge his father? See, it does not make sense at all. BTW, keep in mind they were cousins! Yitzhok was Lavan's in-law, tHey knew of each other from birth, and they all knew Yitzhok was extremely wealthy.
Comment: @רבותמחשבות Can you ask each question separately as a question and I'll do my best to answer it. Based on my knowledge and study, I am trying to present a more holistic picture of the Torah events finding underlying reasons , not simple excuses (tirutzim).


How to detect if iframe's source page is fully loaded into DOM

Question: I want an event to fire after iframe's source page is loaded into DOM to do some customization client side. Please help me.
Answer: If the iframe's content is from the same origin as the containing page, you can listen for the DOMContentLoaded event on it:
theFrame.documentWindow.addEventListener("DOMContentLoaded", function() {
    // ...
});

(If the content isn't from the same origin, I don't think you can hook that event — but that doesn't matter, because you wouldn't be able to do the customization you've mentioned, either. :-) )
Answer: Use onload event:
document.getElementById("iframe-id").addEventListener("load",event=>{
    //Do some stuff when iframe loaded
})


How can we know or measure pain in animals?

Question: Is there any standard way to know how much pain an animal feels when it gets hurt like when a bird loses it's wing or hen when killed etc. All pain sensation points?
Hey I'm new to biology. :)
Answer: Pain is subjective
Pain is a subjective experience; you cannot even tell with certainty how much pain your fellow human is experiencing, which is why we ask people; they then can tell us. Pain relief (both physical and emotional) is a significant part of medicine, yet we still have "pain scales" for self-reported pain, one of the more common ones being the Wong-Baker Faces Pain Rating Scale:

Now, note well that even this scale must be interpreted for the patients. For instance, a patient might look like a 6, but be reporting a 10, in which case, a nurse must try to ascertain their actual level of pain.
My point is evaluating pain is contentious even in humans who can express themselves.
Definition of pain
The International Association for the Study of Pain (IASP; www.iasp-pain.org) defines pain in humans as

an unpleasant sensory and emotional experience associated with actual or potential tissue damage, or described in terms of such damage.

Pain usually involves a noxious stimulus that activates nociceptors in the body that carry signals to the CNS where these signals are processed (and generate responses) including the "unpleasant sensory and emotional experience."
The following are examples of common types of noxious stimuli for different tissues:

Skin: thermal (hot or cold), mechanical (cutting, pinching, crushing), and chemical (inflammatory and other mediators released from or synthesized by damaged skin, and exogenous chemical stimuli such as formalin, carrageenan, bee venom, capsaicin)
Joints: mechanical (rotation/torque beyond the joint's normal range of motion) and chemical (inflammatory and other mediators released into or injected into the joint capsule)
Muscle: mechanical (blunt force, stretching, crushing, overuse) and chemical (inflammatory and other mediators released from or injected into muscle)
Viscera: mechanical (distension, traction on the mesentery) and chemical (inflammatory and other mediators released from inflamed or ischemic organs, inhaled irritants).

Animals need us to interpret their pain into language. For political and emotional reasons, humans are ill-disposed to do so (how could we then justify eating, exploiting, experimenting on animals, etc.). Even into the late '80's, veterinarians were taught that animals didn't perceive pain per se.
How we know animals understand pain
To determine whether animals can experience actual pain (not simply nociception), it is necessary to show that they

can discriminate painful from nonpainful states; make decisions based on this discrimination in a way that cannot arise from evolved nonconscious nociceptive responses; demonstrate motivations to avoid pain; and display affective states of fear or anxiety if threatened with noxious stimuli. In addition, animals experiencing pain might be expected to exhibit spontaneous behavioral changes including sustained signals of distress and impairments in normal behaviors such as sleep.

Animals show all these behaviors. Additionally, there is ample evidence that emotional pain in animals is real. The mere threat of foot shock (electric) induces signs of stress in rats and mice that can be alleviated with anxiolytics (drugs that reduce anxiety).
Even fish show responses to a painful event: guarding behaviors, unresponsiveness to external stimuli and increased respiration, all of which improve with morphine. This is called analogous evidence: evidence that they are, mechanistically at least, directly analogous to pain responses in more complex animals.
Humans are animals
The nervous system of mammals is fairly identical to our own (we are animals). A chimpanzee who is afraid of a pin after being stuck with one 20 times in a row clearly feels physical pain and fear. That a chimp can mourn the death of a parent by not eating and not moving for days clearly indicates that they can experience emotional pain.
In summary:
Pain is subjective. I cannot really tell exactly what you feel if your arm is ripped off (your bird-wing example) or (don't read if queasy type)

 if you are given an electric shock, your throat is slit and, while still bleeding, you are dipped in boiling water to remove your body hair in a whole body hair plucker (which is how most poultry - usually males, not hens, btw - meet their makers).

By definition, only you can tell us.
But common sense and experience tells us it would be painful. And, yes, animals feel pain pretty much exactly like we do. Because we are exceedingly "more alike" than we are "slightly different".
Can animals feel pain?
Pain in Research Animals: General Principles and Considerations
Which Responses Indicate Pain and Which Nonhuman Vertebrates Display Them?<- read this if you really want to know
Evolution of pain
Comment: @Peteris - I'm sorry that you believe what you do, but very little of real science came from that period. Probably the most (hideously) useful information is about limits of endurance, not anything more scientific. Also, I would challenge you to refute me with science, not philosophy. We are **exceedingly** *more similar* than we are *slightly different*.
Comment: This answer is really solid and well-worked out. +1. I totally agree with @anongoodnurse that, in the end, the only way to guess how another animal species experiences pain, is to assess ones own experiences with a similar noxious stimulus and assume it is experienced similarly by an(y) other animal. I also agree with the similarity between species, as analgesics work pretty much the same for all mammals, at least as far as I know.
Comment: @Wiser - Since it's unethical to experiment on humans, most of the information you read about action potentials and waveforms and such were derived from animal studies and applied to the understanding of human physiology. More proof that we are alike.
Comment: so what about those waveforms which you guys were discussing in this question... http://biology.stackexchange.com/questions/25986/what-does-pain-look-like-in-wave-form
Comment: @anongoodnurse and since each species is a bit different and extrapolating from mice isn't particularly accurate, most practical data and measurements on human pain (and other) thresholds comes from the (thankfully) few times/places where we *did* experiment on humans some 70 years ago.
Answer: We work a bit with pain and memory. My understanding is that you can measure what in behavioral field is called "pain" by detecting aversive response of an animal. That is there is always something unpleasant and attractive in nature. Only difference is that pungent smell will not kill subject. Evolution taught animals that bad smells and loud sounds might bring danger and thus pain, so they try to escape. But pain per se is something that is definitely tissue-damage inducing at some point of intensity. Pain is only signal that tissue damaging influence has approached.
ADD: I re-read your question. There is no way to tell whether or not bird feels pain when wings are cut without anesthesia. Nice experiment would be to rip off human's arms and bird's wings while both are in fMRI scanners or other functional brain imager. If same areas of brain light up, it means that feeling might be similar.


Using integrals in physics in a rigorous way

Question: I would like to know how can someone justify rigorously the following argument, which is often involved in the solutions of many physics problems: given $v(t)$, we know that $v=\frac{dx}{dt}$, so we integrate in the following way:  $\int_{x_0}^{x}dx=\int_{t_0}^{t}v(t)dt$. My question is, why are we allowed to "shift" the extremes of integration when moving from $dx$ to $dt$? (obviously, I know that the upper x represents the position at time t, but I'm seeking for a mathematical proof)
Comment: What are "the extremes of integration"?
Comment: Ultimately it comes down to the fact that the two integrals are over different domains. The first is an integral over $x$, in the $x$ domain. The second is an integral over $t$, in the $t$ domain. Luckily, the two variables $x$ and $t$ are related - precisely by the position function itself $x = x(t)$. The fundamental theorem of calculus (the statement that these two integrals are equal) viewed in this way is essentially the change of variables theorem, as the transformation $t \to x$ is given by the position function, and the jacobian of the transform is precisely $dx/dt = v(t)$.
Answer: The statement that if $v(t) = dx/dt$, then
$$
\int_{t_0}^{t_1} v(t) \, dt = \int_{x_0}^{x_1} \, dx,
$$
where $x_0:= x(t_0)$ and $x_1 := x(t_1)$, is precisely the Fundamental theorem of calculus, and a mathematical proof can be seen in the linked article. Note that in that article, $x$ is the variable and $f$ is the function, whereas for you, $t$ is the variable and $x$ is the function.
I would also point out that in your question, you use the expression
$$
\int_{t_0}^t v(t) \, dt.
$$
I would avoid using the integration variable $t$ as the same symbol as one of the limits of integration. I know that it can be understood but it can sometimes lead to confusion when doing changes of variables. So I replaced the upper limits with $t_1, x_1$ as I wrote above.


A manhwa that the female lead had her soul infused with another body so she can have revenge on the people that betrayed her

Question: From what I remember the female lead met the emperor when they were young and they were friends. As time went she killed for him so he could ascend the throne and she fell in love with him. When he was emperor he found her as a threat and the people in the council wanted her dead. Especially the elven knight since she was jealous cause the female lead was head of the knights. A male found her in the ice dungeon they put her after her tongue was cut off and her legs were crushed, so a male that could change his hair from white to black also a prince without a kingdom transfused her soul into another body so she could help him seek revenge of killing the king or emperor.
Comment: Can you give any additional details? Can you indicate more or less when you read this?
Comment: What colour was the female lead's hair?
Comment: Before her soul was infused she had i think ginger curly hair then when her soul was infused the owner of the real body had long blonde hair
Answer: This is almost certainly Justice for the Villainess.

"I won't rest until they're dead." Charlotte has no qualms about murder if it means her beloved Prince Albert can ascend to the throne. But when he accuses her of treason and leaves her to rot in prison, she learns that loyalty is no virtue. 5 years later, Count Kaitel appears before her with a request: "Won't you kill the emperor?"

The synopsis covers the betrayal and revenge themes. The main character, Charlotte, met the 7th prince and future emperor and fell in love with him. Partially with the promise of her becoming empress, she assassinated the other candidates for the throne and made him emperor, only for him to make someone else empress and then accuse her of jealously plotting against the new empress.
She's thrown into a prison in a snowy area to die. It's not exactly an "ice prison", just a prison in a desolate snowy area. Her legs are depicted as "useless", but unless there's a later flashback, her legs were not explicitly broken. Additionally, her tongue wasn't cut off, as she's still able to speak.
If you read the original novel (I haven't), it's possible the details are more explicit/cruel there - that happens sometimes, and could explain the discrepancy.
She's rescued from prison by the adopted son of an archduke. He takes her to a temple in a destroyed kingdom that has immortality and soul transfer magic. It turns out he's the prince of this destroyed kingdom, and has white hair but uses magic to change it to black. He uses the soul transfer magic to transfer her body to that of a comatose blonde maid.

Her original body has slightly curly black hair, not ginger, but the art style sometimes gives it a bit more color. The bit with the elven knight might be explained in a future chapter; this is just based on the first four.


SQL Server 2008 Express 32-bit Import and Export Wizard installation

Question: My first post on StackOverflow, so please excuse me if I am being ignorant.
Lately, I have been playing around with MS Visual Web Developer for work purpose, and I have installed the 2008 Express edition on both my home and work computers.
I only later found out that the import and export wizard for the 2 computers are different: at work I have the 64 bit version and at home I have the 32 bit version. This is causing me tremendous amount of headaches as I was hoping to rely on its functionality to import Access and Excel files which only offers under the 32 bit version.
My question: Is there any way I can install this 32 bit wizard at work separately without having to reinstall the whole MS VWD application? Perhaps as an add-on or service pack or something?
Thanks for any help in advance.
Answer: If you're using SQL Server, install SQL Server Management Studio and do you importing/exporting through it.
http://www.microsoft.com/en-us/download/details.aspx?id=7593


Who Can I Hire To Calculate the Value of An Estate?

Question: My grandfather in Russia recently died, and he was very private about the state of his finances and did not leave a will. Because of that, nobody, not even his son, really knows what he's worth. He owns three properties and was the head of a business, and it's unclear what he had in terms of bank accounts. Is there a specific person who can be hired to do the research on his affairs at death to determine what exactly the value of his estate is?
Answer: Generally, it would be an accountant. Specifically in the case of very "private" (or unorganized, which is even worse) person - forensic accountant.
Since there's no will - it will probably require a lawyer as well to gain access to all the accounts the accountant discovers.
I would start with a good estate attorney, who in turn will hire a forensic accountant to trace the accounts.


Moving a Blogspot blog to a new domain?

Question: I have a blog with blogger.com. And I wanted to move it to a domain name now. i have purchased a domain name with go daddy. I have little technical know-how, so would appreciate any help with regards to moving my blog to a domain name. Help, please?
Like, I want to move all my contents to a domain name.
Comment: @Su' already gave you the best answer, I must also add that setting up a domain from GoDaddy for Blogger is very easy and you don't need any technical knowledge.
Comment: Do you want to continue to use blogger to edit your blog? If you do then the wget answer below won't help you, but I wanted to check before I commented on that answer.
Comment: If the answer is yes, then your question is a duplicate of this one: http://webmasters.stackexchange.com/questions/3466/how-to-have-a-blogspot-blog-in-my-domain?rq=1
Answer: There are instructions for having your blog display at a custom domain, but you should note that this doesn't move anything in a literal sense, eg. no files will be created at a hosting account, etc. (This is probably what you're actually after, but if not be sure to clarify your question.)
Answer: Check out the command line program call wget.  It's quick and easy for recursively getting websites.
<code>wget -r http://the_url_to_your_home_page
</code>
Comment: http://www.gnu.org/software/wget/
Comment: Can you give more details about the function and a link will be great to.

Moving a Blogspot blog to a new domain?


What "formula" do you use to evaluate open-source communities?

Question: One problem I have with open-source is not often the product or documentation, but the level of community involvement and support. Response time for some questions on official forums can take more than a week, which can honestly make a big difference when choosing a platform for commercial services use. However, I find that evaluating the community beforehand is very difficult. How do I know what are the most common issues, and whether or not people are getting support for them? How do I know what problems I personally might encounter based upon my project, which would require some level of community support? Do you have a formula for performing this evaluation?
Answer: I've usually found that relying on community support for anything mission critical is asking for trouble. So I usually stay away from open source unless it's something that I'm confident we can support in-house or there is a commercial support service available for it.
Answer: If your question is posed because you don't want to pay for support, then I think your best bet is to ask questions about a specific project on neutral forums like this and see what others have experienced in terms of support and timeliness of resolution to issues.
If you are willing to pay for support, there are companies that provide commercial support for open source projects, like OpenLogic as an example that could factor into your formula.
Answer: The only real way to evaluate the community is to try it, participate in the community.  Most communities will have good support networks available in one manner or another.  Also many individuals are starting to offer support services for the various frameworks as well, for those looking for a more dedicated resource for problem resolution.
But I find the best way is to just get in there, ask a few questions, poke around at the resources, and really see what is there.


My friend's dad gave her a puzzle to solve, and I've never seen anything like it, any help would be greatly appreciated

Question:
I am admittedly not a puzzle person, but I have never seen anything like this, and I am at a complete loss. I have spent an embarrassing amount of time on some weird theories. Any help would be an absolute lifesaver. Thanks!
Comment: Update: It's actually S'gaw Karen, and from what I can tell there are no online translation tools for Karen. I've done literally all I can do aside from paying a translator.            Friend's dad: 1, Me: 0
Comment: That is simply an example of the Burmese script. I can't translate, but at least you know what it is.
Comment: It definitely is Burmese, translating is is proving to be a bit of a struggle haha. Kicking myself for spending hours trying to figure out some hidden code, when it was just Burmese. Oh well, thanks for your help.
Comment: Do you mind showing the whole page as this photo seems either incomplete or cropped, especially at the right bottom corner. Thanks!
Comment: Try pointing Google translate at it
Answer: Tentative Answer
Even though, as was pointed out in the comments, this is actually simply a text in another legitimate language (S'gaw Karen), we can still approach it as a puzzle since there are no online translation tools, so we will need to use some good old trial and error to get a meaning.
First I endeavoured to transcribe this message as well as possible:
တၢ်ဆါဟံၣ်ဖဲအံၤ
န့ၣ်ပှၤတမၤကွၢ်
COVID-19 ဘၣ်.
တၢ်ဘ...
I found this online dictionary - unfortunately, it requires input from a (presumably) S'gaw Karen-configured keyboard. After a great deal of trial and error and guessing (basically hitting random keys until I got a character looking like one in the picture), and using the hint of COVID-19 as a stimulus, I've made some progress.
If we start with what looks like the first word:

 It looks like တၢ် is the first word, which seems to mean thing or to be some sort of indefinite pronoun. An even start.

For what looks to be the second word:

 ဆါ seems to mean sickness/disease, which is on track with the COVID reference.

Continuing:

 ဟံၣ် seems to mean home/residence, which is certainly on topic!

This one I'm not so sure about, but in context it seems relevant:

 ဖဲအံၤ seems to mean here which might apply to the home above.

Now it gets a bit trickier:

 န့ၣ် is a particle meaning that or this.

Then we have:

 ပှၤ meaning person/people.

Followed by

 တမၤ apparently meaning special/intelligent.

Followed by:

 ကွၢ် meaning look/consider/seem.

This is followed by:

 The word 'COVID-19' followed by ဘၣ် meaning appropriate/correct.

Thus we have the following potential parsing of the sentence:

 [Thing] sickness home here that people intelligent look COVID-19 appropriate

Then attempting to apply some of the basic rules from this basic grammar, we see that (like English) S'gaw Karen follows a subject-predicate-object pattern, and additionally that adjectives follow the noun, and adverbs follow the verb and object.
Attempting to elucidate what parts of speech each word plays in the sentence, we get:

 [Thing] sickness(es) (n) home(s) (n) here that persons/people (n) intelligent (adj) look (v) COVID-19 appropriate (?adj/adv)

If we now attempt to apply those rules to parse this sentence:

 Assuming appropriate/correct modifies the verb look rather than the noun COVID-19 which doesn't make much sense, the only sensible reading I can see of the last few words is intelligent people see COVID-19 appropriately

The beginning of the sentence was still troubling though, but:

 We see on page 45 of the grammar that the word we have translated here is an adverb of place, meaning that we should(?) expect it to be proceeded by a verb. Noting that the second word (sickness) also functions as a verb meaning afflict, and that the word before it (see page 12 of the grammar) turns verbs into nouns, it seems likely that here modifies this verbal noun. The word that being an adjective presumably refers to a previous noun, either sickness or home.

Then suddenly, realization struck:

 The phrase တၢ်ဆါဟံၣ် (sickness house) means hospital!! (Duh!)

Finally, we can extract the following extremely tentative meaning:

 Here in hospital, intelligent people look at COVID-19 properly

Perhaps describing:

 Doctors examining patients for symptoms

Some Thoughts
I've tried multiple alternative parsings. I am almost certain that the first line reads:

 Hospital(s) here/in which place

The second line definitely seems:

 To start with the demonstrative adjective that followed by the word for person/people/someone

However (the one possible alternative parsing I have found), the words following, in addition to our previous parsing, could also be parsed as:

 Negative particle တ followed by try/examine မၤကွၢ်

Which would give a tentative meaning:

 Here in hospitals, people do not examine COVID-19 properly

This has quite a different meaning!
Also:

 The word at the bottom right is cut off but looks like it is the characters တၢ်ဘ. I don't know what it means.
Comment: If anyone can think of a better way to parse these words, or a more obvious meaning, please let me know! I don't think the sentence makes quite enough sense as is.
Comment: Maybe it's more along the lines of rot13(vagryyvtrag crbcyr nccebcevngryl fgnl ng ubzr)
Comment: @Mohirl Gung pregnvayl frrzf yvxr n ybtvpny cbffvoyr zrnavat sbe gur fragrapr, ohg V pna'g frr nal jnl vg pbhyq jbex (jvgu zl yvzvgrq xabjyrqtr bs F'tnj Xnera tenzzne npdhverq gbqnl). Vs jr sbyybj gur frrzvatyl boivbhf pyhr gung gur svefg guerr jbeqf (*cebabha fvpxarff ubhfr*) zrna *ubfcvgny* gura gung trgf evq bs gur jbeq *ubzr*, naq V pna'g svaq n jbeq gung zrnaf *fgnl*.
Comment: Impressive. +1 :)


how can i attenuate mobile signal completely(maybe 90%) and please suggest me the wall thickness ,as i want to use copper or aluminium

Question:
please help me as i want to make a den for my dog that completely attenuates em waves of phone
Answer: I will assume that your target band is 1-3GHz, typical for mobile phones.
The thickness of the shielding you need is related to the skin effect. At 1GHz, the skin thickness is ~2μm for copper and 3μm for aluminium foil. To effectively block the signal (attenuate by ~60dB), you will want the foil to be about 10 times as thick, so you're looking at 30μm for aluminium. 15μm is what you get with standard cooking foil which will somewhat work, but you should aim for thicker varieties.
The maximum size of holes you can accept is related to the wavelength. At 3GHz, the wavelength is about 10cm. Again, to effectively block the signal you will need holes at most about 10 times smaller, about 1 cm.
How much attenuation your dog requires is another question. Probably none at all.


Looking for the smoking count or rate per census tract in New York State

Question: It seems like this only exists at the county level here - PA-Percentage-of-Cigarette-Smoking-Among-Adults
Answer: Sorry to be a bummer, but I don't think it exists.
For anything at census tract level you (almost always) need to go to either the SF1 files or the ACS files from census.gov. SF1 are just demographics, ACS are a little more of the 'other' stuff.
The 5 year survey has the highest granularity.
http://www2.census.gov/programs-surveys/acs/summary_file/2010/documentation/5_year/ACS_2006-2010_SF_Tech_Doc.pdf
Scroll to the data dictionary toward the bottom to see what you can get. I didn't read the whole thing but did a Ctrl+F for 'smok' and had zero results.
I think what you have is about the closest you will find.
Comment: Before someone down votes me for not answering the question- No solution exists is an answer, so prove me wrong before you fire that -1
Comment: That's generally not how stackexchange works from my experience. I would have answered the same. The best data that exists publicly would likely be from the BRFSS at the county level.
Comment: Not how it's supposed to, but every now and again someone gets a little trigger happy. Never happened to me, but I've seen it done to others.
Answer: Rate of smoking is not a question asked on the American Community Survey, or, as far as I know, in any US Census Bureau instrument. Here's a page from the US Census Bureau outlining the health topics they cover. The top level categories they use to organize it are:

Disability
Expenses & Investments
Fertility
Health Insurance
HIV/AIDS
Small Area Health Insurance Estimates

(Not all of these are part of the ACS, and those which aren't won't be published to the census tract level. Even the "Small area" health insurance estimates only go down to counties.)
Generally, health statistics are rarely tabulated at small geographies like census tracts because of concerns of publishing personally identifiable information, as well as, probably, the cost of data collection at that scale.


How to know Intel(R) HD graphics version?

Question: I've Intel Pentium G2030 3.00 GHz processor with Gigabyte H61M-S1 Motherboard.
I am using Windows 7 OS.

which Intel(R) HD graphics version I have?
Answer: I like wikipedia's "List of Intel Pentium microprocessors" for this as it lists processors by generation, and in a table so you can get a sense of how yours compares to others.
There's also Intel Core to see how those compare and the CPU Architecture pages; for your G2030 see the Ivy Bridge page <en.wikipedia.org/wiki/Ivy_Bridge_%28microarchitecture%29> which gives GPU clock rate which might help some : 650MHz Normal, 1050MHz Turbo.
Also <en.wikipedia.org/wiki/Intel_HD_and_Iris_Graphics> is helpful; for Ivy Bridge it points to <www.intel.com/support/graphics/sb/CS-033757.htm> and there you can look up your processor.
Quoting Intel, for "Intel® Pentium® Processors 2000/G2000 Series with Intel® HD Graphics" :
"The product... do[es] not support the following features: Intel® Insider™ technology, Intel® InTru™ 3D Technology, and Intel® Clear Video HD Technology."
DirectX : 11.0
OpenGL : 4
OpenCL : No
Shader model support : 5
Intel® Quick Sync Video : No
Intel® Wireless Display : No
Answer: It just ships with Intel HD graphics, no number:
G2030 processor
Benchmark
Comment: I saw it, but if I know at least specs of Graphics(like speed)
Comment: Added a benchmark for you above, it roughly scores 119 points, the current highest rated card is 11.181 points.
Also battlefield for reference: https://www.youtube.com/watch?v=5iN8_jgkYYo


G09 how to I prevent Na-O bond formation doing DFT on a sodium carboxylate?

Question: I am trying to determine Gibbs free energy of solvation for a sodium salt of an alkylcarboxylate. B3LYP/6-31g. The minimized structure makes covalent bonds between sodium and carboxylate oxygens. How do I prevent this?
Thanks
Comment: How did you come to the conclusion that the bonds are covalent? Even an inaccurate level of theory like B3LYP/6-31G doesn't produce these kinds of errors.
Comment: I think it's important to remember that DFT calculations (e.g., Gaussian) produce a set of atoms and XYZ coordinates. We like to see "bonds" in visualization tools, but they are inferred based on interatomic distances.
Comment: see my answer below about covalent
Answer:
How do I prevent this?

You don't.
Ionic bonding is an idealization we do not expect to be realized in pure form between individual atoms, even in cases where the electronegativity differential would seem to be quite large. As described here, purely ionic bonding is more closely approached between multiatomic entities for which the molecular-orbital structure favors such bonding.
Moreover, the boundary between "ionic" and "covalent" bonding is really indistinct; what appears to be ionic bonding may in many cases have a covalent interpretation. The lattice structure of calcium carbide offers one such case.
Comment: @NonclassicalCarbocation a visualisation tool will create an image based on interatomic distances. At least with the information usually included in a fsck file. You need to analyse the calculation further to judge the bonding situation. You must not equate a line in a program between two balls as a covalent bond. Study your system, one way of doing that is described in the question I've linked, but there are others. However, be aware that there will always be room for interpretation. As with your original goal, you should follow the literature to find the best approach.
Comment: Reminds me about https://chemistry.stackexchange.com/q/40729/4945 However, I think OP is not interpreting their calculation correctly, and to me the question isn't really clear.
Comment: how do I know it is covalent? when I look at fchk file, visualization draws two bonds between oxygens and sodium and the atoms no longer bear any charge.  i have no problem modeling ammonium bromides, just getting stuck with sodium carboxylates.


How can i filter songs using persistent id

Question: ì have an iPhone application in which i should filter the songs by genre or album, filter the albums by artist etc. But i have a doubt about how to filter items. I read in apple's documentation that for example to get songs for a specific album you should make a MPMediaPropertyPredicate in which you specify the album name as the value of the predicate and  MPMediaItemPropertyAlbumTitle as property. But in their documentation they say that we can filter items using also the persistent id of an album for example.
Could someone please give me an example in which i could load the songs of a specific album using the persistent of the album.
Thanks.
Answer: An album doesn't have a persistent id. The iPod library only has track objects basically - it's not a relational database with artist, albums and track records.
If you want to load all songs from an album, you simply search on album/albumartist texts.


How to recruit participants for online experiments?

Question: We are currently doing a study where we thought it might be smart to try out the possibilities of recruiting participants from the Internet. I was thinking it might be best to ask more experienced members, where would be the best kinds of places to publicize the experiment, and what strategies they would recommend to this?
Comment: Do you mean "publish" as in publish a paper about the experiment, or "publish" as in publicize the link so people visit it, or what? Please clarify.
Comment: Thanks a lot, point well taken. I did mean this in the sense of publicize, I now see how poorly phrased it was for academia. The problem I would say is still rather general: The internet offers a potentially infinite pool of participants to take a part in our experiments with close to no costs in the form of people surfing the web. It seems worth a thought how best to reach these audiences for attentive participants, who follow the instructions and make an effort. We'll continue to look into this. Thanks for the corrections though, and sorry for spamminess.
Comment: Ok, since you have clarified we were able to reopen the question. Hopefully this can get answers now.
Comment: If it's truly considered an "experiment", there may be limitations on where/how you can publicize it. What's the nature of the study? For example, if you're asking health-related questions, if it's some type of mental health survey, etc.. Even if it's just a "simple" survey, there still may still be policies and regulations that you'll need to follow. In some cases your only option might be to follow your institutions procedures for recruiting/publicizing your type of study -- That can still be done via internet, just within the institutions' system for publicizing & recruiting participants.
Answer: One approach that has become popular amongst many social and cognitive scientists is the use of Amazon Mechanical Turk, which is an internet piecework marketplace.  Many people have used this for recruiting study participants, and IRBs have been quite receptive to its use.
Designing studies for Mechanical Turk is challenging, and presents different issues than designing for in-person studies.  A number of online resources exist that discuss the advantages and challenges (e.g., this blog, this paper, and this website).  Mechanical Turk also poses sampling issues---as has been noted, however, typical recruitment methods also end up getting almost exclusively WIERD participants, so it's unclear how much of an issue that actually is.


Reclassifying a Curvature raster

Question: I am trying to reclassify a profile curvature raster generated by the Curvature tool available in ArcGIS into three classes following the tool help where it is reported that;

...a negative value indicates the surface is upwardly convex at that
cell. A positive profile indicates the surface is upwardly concave at
that cell. A value of 0 indicates the surface is flat.

My Curvature raster' values range between -4.726 to 0.543. By supplying class breaks (-4.726, 0, 0.543) in the Reclassify tool yield spurious results where pixels having values == 0, as separately identified by raster calculator, are more in numbers (pixel count) than it should be!
What are optimal class break values to get accurate reclassified Curvature raster?
Answer: It sounds like you want a Sign function, which I don't think exists in the Raster Calculator.  Instead, you could nest Con functions, like this:
Con("ras"==0,0, Con("ras"<0,-1, 1))

From the help on the Reclassify tool, "the higher end of the lower input range is inclusive, and the lower end of the higher input range is exclusive."

Reclassifying a Curvature raster


Can't receive text messages or phone calls after last Windows update

Question: After the last Windows update I had to hard restart my phone and start all over again because it kept restarting over and over. About a week after that my phone was spotty when it came to me receiving text messages and phone calls. Now I only get text messages if I'm calling out and they come all at once. I can call out and text out just not receive. T-Mobile says there's nothing wrong with my line and that it's probably a software issue. Can anybody help me with this? Thank you
Comment: What version of Windows 10 Mobile are you running? Are you enrolled in the Windows Insider programme?
Comment: What device are you using? Which version of the operating system is reported as installed?
Comment: I have no idea which Windows 10 I have. I have an Alcatel Fierce XL. I am signed up for the Insider program... I don't think I am. My phone last updated the middle of November. The more I look into this phone the more I'm finding out that I'm not the only one with this phone issue.
Answer: So I went to T mobile and it seems there have been a number of people with my problem. The manager switched out my sim card with a new one and it seems to have fixed the problem.
Comment: If this don't help HArd reset maybe is solution


Hawt.io web application - user permissions

Question: I've got a question about hawt.io security.
I've installed hawt.io as a web application (currently its embedded jetty but we have an option to use tomcat in an embedded / regular mode as well).
Hawt.io visualizes the JMX mbeans tree of the same process, we don't connect to remote servers, everything is local.
What I would like to do is to find the best way to provide an authentication and authorization mechanism to be used:

User's authentication: should be done preferably via LDAP
User authorization: some users can gain full access to all mbeans, others are restricted to not execute mbean operations, but only read attributes.

I thought that I can install a web filter, in jetty I can do it outside the web.xml and check requests, but since hawt.io uses POST web method to communicate to its internal jolokia, the identifier of the operation execution is inside the body of the request, so I don't really have an access to it from within the web filter since in Java Servlets I can read the request body only once. I know I can provide a 'fake request', but maybe there exists a better solution.
Maybe someone can provide relevant configuration snippets for configuration of such an installation. Thanks a lot in advance
Answer: For role based authorization you can query up-front if the user has access to a given mbean/operation/attribute.  If you implement this interface
you can probably integrate with some server-side authorization for JMX.  By default hawtio uses a dummy implementation that lets everything through.  This all was originally designed to work with the JMX guard stuff implemented for Apache Karaf which exposes the same mbean but actually does restrict access via ACL configuration.  Anyways, the client-side javascript is set up to locate this mbean by scanning for "type=security;area=jmx", just set a higher 'rank' attribute in your mbean and the javascript will use it.