Magic In Dresden Files Universe

Question: In The Dresden Files universe is there a limit to what magic can do ? And how does it compare to other magic in different series like harry potter for example?
Answer: There are no theoretical limits. Magic can, given enough of a power source and a properly constructed spell, do literally anything. The Laws of Magic are a simple enough guide to the possibilities; magic can warp minds, alter flesh, kill by the droves, and even rewrite time and space.
Once active, however, a spell still has to work in the "real world", so to speak. Physics plays more of a part than you'd expect. For example,  let's take Harry's favorite fireball. You can build that spell to just directly create heat for the fire, but that's pretty exhausting on the magic. You could also build the spell to just move nearby heat around, stealing it from other sources to make the fire hot. That's a lot less intense on the magic, but might make it harder to do in a frozen tundra.  Point is the heat for that fireball has to come from somewhere.  Magic doesn't provide a free lunch, just lets you bend how to pay for it.
If you wanted to do something catastrophic, like alter history, the energy involved becomes insane, fast. Really, time only flows in one direction,  and we haven't figured out any rules that change that on Earth.  So every ounce of power you get would have to fight the natural order of the weight of time, just to get into the past,  even slightly. Then the spell would need more to change whatever you needed,  more to make things flexible enough for the timeline to accommodate, more, more, more.
So practice reigns rather than theory and the effort involved in bending the world to your whims usually wouldn't work out. A single wizard can only channel so much power on their own. Gathering more would require focuses for something elses energy, places to store the energy up, preparation,  more time, etc.
The biggest magics seen actively so far in the series -

 Kemmlers Darkhallow and the Red Court's bloodline slaughter

are usually shortcuts past all that, using some form of human sacrifice to harvest life energy by the truckload.
There are beings that can break the practical boundaries,  but by and large they exist under their own laws and natures (or laws of nature) and are constrained from large scale meddling. Examples include -

 Nicodemus' pentagram traps, which per Harry needed some sort of divine level of Hellfire to work and implied the involvement of Lucifer, but which in turn allowed certain archangels to interfere to counterbalance his influence; also Mab altering weather patterns and invoking an early Winter in Chicago in the same book, which falls under her perview as Winter Queen.

To answer the Harry Potter question, it looks like the other answers have it pretty well covered.  As used up-front in the Harry Potter books, magic is a very structured regulated and known quantity, and while there's deeper effects related to intentions they don't get into that much.  Magic in The Dresden Files is fueled by life and emotion and energy, but it's form and effects is only limited by the wizard in question, his/her resources, and imagination.
Comment: I'd argue that Nicodemus's pentagram traps were roughly equal in power to the two you mention.  While it's true they had broader effects, those traps were sustained and constrained and required the literal intervention of the Prince of Darkness to create.  The Red Court slaughtered hundreds to do some thaumatergy (scaling up what Dresden has done with Play-Dough!)...it is impressive but doesn't really compare to a demigod telling reality how it should be shaped for a while.
Comment: @Jeff - true, missed that one. Then again, one of those was a rite to Make a Demigod, so YMMV
Comment: @Jeff - added that as an example, so thank you for suggesting
Comment: Time can clearly be meddled with, or law #6 (Thou Shalt Not Swim Against the Currents of Time) wouldn't be necessary.
Comment: @Brian - er, didnt say it couldn't, just that it's hard enough to be wildly impractical. There's a discussion that backs this up, as well as some evidence that it *has* been done despite this, in Cold Days. It's easier to fiddle with current time, rates of passage and such, and we do see that happen in spots as well
Comment: The Sixth Law is, as I recall, explicitly called out as almost-irrelevant since it's almost impossible to do in the first place, so almost no one *would* do so even if it were legal.
Answer: tl;dr: So far we have not seen any limit to what magic is capable of doing, so long as the magic user has the skill, strength, and talent to channel enough magic to do it.
Compared to, e.g. the Potterverse, magic in the Dresden universe appears way more powerful, though I don't know that anyone in Harry Potter ever really tested the limits of what they can do. Potter-style magic is more structured: spells require wands and magic words and such, which may be the limiting factor there; Dresden-style magic is completely internal, and the words and wands and such are merely use to aid the spellcaster, and are not required.

There are actually a number of different kind of magic in the Dresden Files universe, with different characteristics.
Most of the humans and semi-humans in the series use a standard form of human magic that relies on two things:

The naturally-occurring "magic energy" in the environment, and
The ability of the wizard to channel it through their body.

We have seen wizard-type characters perform some pretty impressive effects (in particular, read the battle with the Red Court at the end of Changes). The only limit to their effects seems to be the practical limits of the wizard's body more than anything else. After using lots of high-powered spells, Harry is often exhausted and unable to conjure up anything strong anymore. This is also why wizards use so many objects: they are focus devices, allowing them to perform stronger effects with less effort.
The other kind of human magic we see is "blood magic", used by the bad guys. In this case, the wizard uses human sacrifices to build up a lot of power very quickly, without their needing to gather it into themselves first, thus making the process easier. Again, the climax of Changes shows perhaps the biggest example of this so far: a single blood-powered spell was able to

 instantly destroy every single Red Court vampire in the world.

which is a pretty damned powerful spell.
Besides those, however, we also see creatures like the fae capable of performing feats of "magic" that dwarf anything we've seen humans do. Their abilities do not appear to be the same kind of magic that humans use, rather it's some sort of innate ability they have. In particular, I don't think we've ever seen a far tire after using their powers, and we've seen the Faerie Queens do impressive things (up to and including total control over the climate.) It appears that their power in the NeverNever is essentially unlimited, but even on Earth it's really strong.
Fortunately, the fae are constrained by their nature, meaning they are unlikely to run around willy-nilly doing massive magic spells. They generally stick to the things they know; most of the cases where we've seen a Faerie Queen flip out was when someone disrupted the natural course of things they they were responding to the threat.
Comment: So they can do all the stuff like transfiguration,Telekinesis etc?
Comment: @LiamBrown Dresden frequently uses some form of Telekinesis in battle, either using his staff as focus or via as predefined blasts stored in his rings. Different mechanisms for turning into a wolf are discussed in the second book "Fool Moon".
Comment: @LiamBrown, In addition to the wolf transformations in Fool Moon, the second Law of Magic is "Thou Shalt Not Transform Others" (clearly implying such transformation is possible). There's also law #3, "Thou Shalt Not Invade the Mind of Another" (similar to Potterverse's Legilimency) and law #4,  "Thou Shalt Not Enthrall Another" (similar to Potterverse's Imperius Curse)
Comment: plus, Harry routinely mixes potions and creates/uses magic items. I believe there is also a law against using time travel magic, again implying that it's possible.
Answer: Dresdenverse operates on a "Clap Your Hands If You Believe" style of magic. Belief creates truth (for mortals, anyway).
Whether that belief is in Magic itself, as Harry believes, or belief in the Divine, as Michael believes in his actions and duty as a Knight of the Cross, or any other belief, that is how supernatural effects are created.
To demonstrate the difference, the only thing preventing Harry from being atheist is that he's met archangels; Harry can't use a cross to ward off vampires. However, Harry's belief in magic does allow him to use his mother's pentacle (representative of the five Western classical elements, bound by human will) for a similar purpose, and Michael can use crosses to repel the creatures of the night.
Similarly, so many people believe in the "Shroud of Turin" held by the Vatican, it has power. But that is not the actual Shroud of Turin.
Supernatural creatures may operate slightly differently, in that they are born for a purpose and excel at that purpose; faeries and demons and so on may not even "believe" in things with the same sense that mortals do.
Although mortal magic has few-if-any theoretical limitations, it has practical limitations such as obtaining enough power to fuel a given spell, and skill to put the spell together.
Finally, the White Council of Wizards imposes a few more limitations on mortal practitioners. While the Laws of Magic don't prevent certain spells from being cast, someone who casts such spells invites a Warden's sword to a tea party with their neck. The Warlock's head is not invited.

Thou Shalt Not Kill
  (This only applies to killing with magic, not killing with mortal means; also, only killing "people" counts, and monsters like vampires and faeires aren't "people")
Thou Shalt Not Transform Others
Thou Shalt Not Invade the Mind of Another
Thou Shalt Not Enthrall Another
Thou Shalt Not Reach Beyond the Borders of Life
  (This only technically applies to human corpses; making a zombie T-Rex toes the line without crossing it)
Thou Shalt Not Swim Against the Currents of Time
  (Even inspecting the future is frowned upon, although the Gatekeeper seems to be able and permitted to bend this rule)
Thou Shalt Not Open the Outer Gates
  (Also applies to the Outsiders from beyond the Outer Gates; even learning about the Outer Gates and the Outsiders can be punishable; naturally, the Gatekeeper is exempt, as guarding the Outer Gates is among his duties)

For all of the above Laws, the Wizard with the position of the Blackstaff is exempt.
Answer: There are no limits on magic itself.
The limitations come instead from how much one's body can endure. As Harry has said many times, magic is about preparation and/or being able to control the raw magic which you evoke. Instances are given many times of wizards who have attempted to evoke too much power in too short a time and killed themselves in the process.
If you wish to bring about great changes with magic, you either have to accomplish it over a very long period of time, with much research and planning, or you have to be able to endure your raw magic overwhelming you.
Fairies on the other hand have much more power and a greater and inherent control of it, but faeries are bound by other restrictions, particularly governing their interactions with the mortal world.
Answer: Yes, Dresden Files has limits to what it's magic can do.  The broadest bit of this is that you can't use magic to make something happen unless you truly believe it should happen.  You can't use magic to find your keys unless you truly believe your keys should be found.  You can't use magic to throw a fireball unless you really believe that fire should be thrown.  And you can't use magic to kill someone unless you truly believe they should be dead.
Most magic we see in Dresden is thaumatergy - forging a link between something big and something small.  In one book, Harry uses this to create a detection web in a hotel - he takes a tub of play-dough and puts bits of it all over the hotel.  He then uses the remainder in the tub and links them all together magically.
A villain from an earlier book used Black Magic (defined as magic which violates one of the White Council's Laws) thaumatergy to kill people at a distance - he had a piece of the person (in this case, bodily fluids and hair), powered a magical rite with feelings of lust, and used a thaumatergical connection between the person's bits and the person to forge a link between them and a small animal.  He used that connection to rip their hearts out from across a city.
There's dozens more examples, but thaumatergy is the simplest type of magic for a mortal to use.
Evocation is another type of magic.  It deals with moving and transforming energy.  Harry is extremely skilled and has a natural talent for evocation.  He can use it for several things, most notably his common spell: fuego.  With this spell (or any of the variants) Harry conjures fire.  He can throw fireballs, create pillars of flame, or any of a number of other uses.  This doesn't come freely, though - the energy comes from somewhere.  Sometimes it comes from within Harry, other times he channels it from the surrounding environment.  Notably, he once used a massive fire spell to

 Freeze part of a lake, creating a sheet of ice thick enough to support several people's weight so they could escape from a sinking ship.  He channeled heat from the lake into the fire, causing the lake to partially freeze.

Magic can also be used to enhance things and make them more of what they already are.  Leather is a tough material, and Harry famously has used magic to enhance his leather duster to the point where it can stop most bullets.
Potions are made in a similar way - take things which have a desired quality, mix them together and add magic to get a short-term magical effect.  Using tequila, a large bill, ashes from a romance novel, and a few other things, Harry brews a 'love' potion at one point.  It gives the drinker the feelings of love (or, given who helped him make it, lust).
Magic can also be used to summon things from the Never Never (or Beyond), to create illusions, to mess with people's minds, to heal, or any of a number of other uses.
In short, Dresden's magic is both more and less powerful than Harry Potter's.  It can't be used (well) untrained, it doesn't require any tools or artifacts, and there's always a cost to what you get.  That said, it can do lots of things Harry Potter's magic isn't shown to do.  It can turn you truly invisible (not just Disillusioned), can control the winds and elements, can reverse gravity...but it takes a great deal of skill and training.  You can't simply hand an 11-year-old a stick and watch magic happen.
Comment: So how is it both less and more powerful than hp magic?
Comment: It is more powerful because it is much more flexible and doesn't have a single point of failure (Dresden **can** cast a spell without any tools or focus, it's just harder.  Potter **needs** a wand to do focused magic).  It is less powerful because it is harder to learn and requires and external power source.  Potter can **Wingardium Leviosa** all day, but Dresden can only manage a few big spells before needing a rest.
Comment: ty jeff! From what i read thats true but dresden uses brute strength not control like molly maybe thats why it seems he weakens faster than other wardens
Answer: I keep seeing references to Harry's use of fire, Harry is not an evoker, he is very limited in it's use, that's why he carries a blasting rod. Harry relies heavily on tools to focus magic from evocation school. Morgan from the wardens on the other hand is a true evoker and does not rely on such devices to cast such down and dirty raw magic as Harry puts it.
Harry is often quoted as saying >given enough time and couple items there's nothing a Wizard couldn't accomplish.
Fae operate at different rules than humans and they are not restricted from messing with time. they can stop people from aging they can manipulate doors to allow people to go foward and backwards in time etc.
Comment: Dresden is absolutely skilled at evocation.  He says so himself - he's got the touch for Boom magic.  His problem isn't skill, it's finesse.  That's what his blasting rod gives him - control and focus.  Things that come from practice and experience, not natural talent.
Comment: Dresden ***starts off*** bad at evocation.  He progresses extremely quickly though.  In *Summer Knight* he's doing it without foci at the Walmart fight, and later he's tapped to **teach** evocation prior to *White Knight*.
Comment: Evokers require great finesse and control and in the first book during his convo with Morgan he states that he is not an evoker. Evokers do not require blasting rods and charms to do there magic.
Comment: do you know what page that scenario is on as i don't read e-books i only read paper books, i remember him being hard pressed to use evocation in that scenario because he was with out his blasting rod. but it's been a few years since i have read the earlier books.
Comment: I don't have a page reference for the Walmart fight, but it's in *Summer Knight* and takes up (IIRC) most of two chapters.  His teaching at Camp Kaboom was one of the major secondary stories in *White Night*.  It's when he and Ramirez dealt with the ghouls.
Comment: I have the book in hand i just thought it would be easier to find what you meant instead of searching some 200 pages.

If you are talking about the fight against the shambling horror with Murphy in a garden center, i don't remember any evocation except for forzar, his concentrated air spell that he used to knock over shelving. he defeated the shambling with the blue beetle and Murphy wielding a chainsaw.  I will have to search the book and confirm that.

As for the ghouls he didn't have to worry about finesse or collateral damage because he was outside. he just let loose.

Magic In Dresden Files Universe


How do I specify a filetype in a Google search?

Question: Is there a syntax to specify a filetype in a Google search? What is it? (I'm looking for PDFs.)
Answer: From Google Help about Special Search:

If you prefer to see a particular set of results without a particular file type included (for example, PDF), simply type "-filetype:pdf" within the search box along with your search term(s).

Actually, the correct syntax is – without the dash:
filetype:pdf

Answer: to search java pdf notes,type the following in google search bar
filetype:pdf java
and you will get all pdf's related to java.
supported values for filetype are pdf,doc,mp3,xml,ppt etc
and don't forget to include ":" between filetype and its value
Answer: https://support.google.com/webmasters/answer/35287?hl=en#:~:text=You%20can%20use%20the%20filetype,term%20%22galway%22%20in%20them.
Other have already pointed the pdf, I'm pointing here a more complete article from Google support with all the filetypes available to use with the filetype: operator
filetype:

It's a small article so I will paste here for everyone, to save your clicking:

File types indexable by Google
Google can index the content of most types of pages and files.
The most common file types we index include:

Adobe Portable Document Format (.pdf)
Adobe PostScript (.ps)
Autodesk Design Web Format (.dwf)
Google Earth (.kml, .kmz)
GPS eXchange Format (.gpx)
Hancom Hanword (.hwp)
HTML (.htm, .html, other file extensions)
Microsoft Excel (.xls, .xlsx)
Microsoft PowerPoint (.ppt, .pptx)
Microsoft Word (.doc, .docx)
OpenOffice presentation (.odp)
OpenOffice spreadsheet (.ods)
OpenOffice text (.odt)
Rich Text Format (.rtf)
Scalable Vector Graphics (.svg)
TeX/LaTeX (.tex)
Text (.txt, .text, other file extensions), including source code in common programming languages:
Basic source code (.bas)
C/C++ source code (.c, .cc, .cpp, .cxx, .h, .hpp)
C# source code (.cs)
Java source code (.java)
Perl source code (.pl)
Python source code (.py)
Wireless Markup Language (.wml, .wap)
XML (.xml)
Search by file type

You can use the filetype: operator in Google Search to limit results to a specific file type.
For example, filetype:rtf galway will search for RTF files with the term "galway" in them.


What to do about all the wannabe-epidemiologist questions that propose to redefine CFR?

Question: I've lost count of these, but besides' the HNQ'd one there have been numerous dupes, but all of them have one thing in common, they weave some naive (conspiracy?) theory that the true CFR ("death rate") is about 40% for Covid-19. That the first question got HNQd is perhaps understandable, but unfortunately it seems to have blown wind into subsequent questions...
Answer: These should simply be closed as a duplicate of: Does COVID-19 have a mortality rate of 41%?
If that question does not seem sufficiently catch-all, we could edit it to be more general and cover the answers given.
I don't feel like it's worth any more effort on this line of questioning: it's misguided and as suggested here has a smell of conspiracy theory that isn't grounded in any sort of truth.
Comment: note: I edited the title slightly to try to be a bit more catch-all and include the equation for calculating CFR, since that's the core of the question rather than a particular number.
Answer: Where there is moving data depending various factors, then maybe create a community wiki with an answer and keep updating that?
Comment: the case fatality rate depends on who is being diagnosed and at what time  so will differ from country to country depending on how they are being diagnosed and over what time period as well as possibly what strain of the virus.  That's why I was suggesting a wiki because there are too many variables.
Comment: I don't think this is a good candidate for a community wiki. Wikis are good for questions like "what are some ways to solve this?" but not so good for "what is the correct solution?" My knowledge of epidemiology is thin but I'm pretty sure CFR is well defined and has a _correct_ answer.


How do you disable message suggestions in the web interface?

Question: Gmail shows response suggestions to emails I haven't responded to yet. I would like to disable them. Can it be done? If so, how?
Comment: [This feature will be available in the near future](https://www.theverge.com/2018/9/20/17881944/gmail-smart-reply-desktop-turn-off-optional).
Comment: This might not be a suitable solution for you, but the answer suggestions are only available for certain languages. So if you switch your Gmail user interface to another language (or, perhaps, a different English locale), you might happen to disable them.
Comment: That was a clever idea. Unfortunately, changing it to UK English didn't work.
Answer: Great news! As of October 2018, Google have finally relented, and now allow Desktop / Web interface users to turn smart replies off.
It's about half way down the default "General" settings tab, under Smart Reply. Turn it off and you will no longer get the red automatic suggested responses buttons.

While you're looking at settings, if you're the kind of person who prefers not to have your emails written by a robot, you might also want to check that "Smart Compose" (autocomplete for emails) is also turned off. That's also in the General tab, about a third of the way down.
Answer: So I played around a bit and found this.

Click on Settings
Then under general tab, you will find an option which reads Nudges
You can make the changes from there.
Comment: I found those as well. I believe the nudges are a different feature, which remind you to respond to messages if you haven't responded in a while. I have them disabled but the scripted responses are still appearing.
Answer: As of early summer 2018, Gmail does not offer a way to disable the "smart-reply" feature in the web interface per this blog post.
However, users have reported being able to conceal it using AdBlocker. Refer to this Stackoverflow thread for instructions how.
Answer: Best I could tell, you can't disable the "smart reply" feature in the web interface (as of this writing: Sept 7, 2018).
However, if you use an ad blocker (e.g. uOrigin or Ad Block Plus) or other plugins (e.g. Custom Style Script) that can mangle the web page, you can block them.
I added a custom filter of:
<code>mail.google.com##div[data-message-id]+div table .brb
</code>
Additionally, I tried disabling them from the mobile interface, but that setting doesn't seem to affect the web interface.
Discussion here on google group also seems to support that they can't be "disabled" in a proper way within Gmail.


As a Canadian citizen living as a legal resident in the United States, with no income: do I need to file in Canada?

Question: I am a Canadian citizen but I married an American and live as a legal resident in the US.  My husband supports us and I did not bring in any taxable income in 2012.  Do I need to file a Canadian return?  If I make money in 2013, will I need to file in Canada at that point?
Comment: The answer may depend on other factors not disclosed.  When did you leave Canada?  Do you maintain any ties to Canada, e.g. drivers' license, health card, property, investments of any kind?
Comment: OP here.  I left Canada in January of 2012.  I have a Canadian passport, but no health card, driver's license, property, or investments.
Answer: If you have non Residency status in Canada you don't need to file Canadian tax return. To confirm your status you need to contact Canada Revenue (send them letter, probably to complete some form).


Is it possible to have mass with zero volume?

Question: As we had always studied that matter occupied space and has mass and our universe is made of matter so do that mean that there is no case where mass is present without volume .
Comment: The modern definition of mass used by particle physicists has nothing to do with space at all. Mass is defined in terms of the square of a systems energy-momentum four vector.
Answer: You are mentioning three things, matter, mass and volume.
Now mass (as the comment says) is just the square of the energy four vector.
Now I think what confused you is this from wiki:

In classical physics and general chemistry, matter is any substance that has mass and takes up space by having volume.

So basically you are talking about ordinary matter, that is made up of atoms, and takes up volume, and does have mass.
Now you are asking whether something can have mass, without having volume. If you include elementary particles, then the answer is that you could define mass (the square of the energy four vector) as the rest mass of an elementary particle, and in that case:

elementary particles, with rest mass, defined as point particles, having no spatial extension (volume), do exist, like the electron, quark
Answer: I think it is not possible. Although we may not know the specific volume associated with an arbitrary mass, a zero-volume mass would imply a black-hole as its characteristic radius would be less than the Schwarzschild radius. However, as far as we know, all blackholes (densiest bodies) have a non-zero characteristic volume.
Comment: that's an interesting argument, but it's probably dangerous to assume that general relativity applies in the usual way at the scale of elementary particles ;)


Pattern recognition and Machine Learning reference

Question: My main reference for machine learning and pattern recognition is Pattern Recognition and Machine Learning by Bishop. But I want a complementary reference to this which has more exercises and explains the mathematical stuff in more details, e.g. formulas and proofs.
Comment: The book by Duda, Hart and Stork may help.
Comment: @AtulIngle: Pattern classification? That's a good one. Thank you.
Answer: Another good book is:
 - Pattern Recognition by Theodoridis and Koutroumbas
It's about classifiers, features and clustering in the context of pattern recognition.
It contains all the mathematical stuff you want, and backs everything up with references to papers, books, etc. It has no exercises, so for that you need to look somewhere else.
Also see this StackOverflow question on the matter.
Answer: Pattern Recognition by Theodoridis and Koutroumbas (Suggested above) has a companion Matlab book which has lot of Matlab exercises and goes along with the main text book. Check it out>>
Introduction to Pattern Recognition: A Matlab Approach
Answer: The most popular choices seem to be

Machine Learning: a Probabilistic Perspective by Murphy
Pattern classification by Duda et all
The Elements of Statistical Learning by Hastie et all. It is free from Stanford.
Mining of Massive Datasets, free from Stanford.
Bayesian Reasoning and Machine Learning, free available online.
Learning from data. by Abu-Mostafa. It comes with Caltech video lectures

Also noteworthy

Information Theory, Inference, and Learning Algorithms by Mackay, free.
Classification, Parameter Estimation and State Estimation by van der Heijden.
Computer Vision: Models, Learning, and Inference, by Prince
Probabilistic Graphical Models
by Koller. Has an accompanying course on Coursera.


Using Roku's USB for ECP 'query' commands?

Question: I added an ESP8266 nodeMCU for TV and SoundBar IR commands. It also provides a LAN server delivering an HTML/javascript based remote controller to my devices - computer, tablets and mobile phones.
I use this same remote setup for both a Roku4 w/ an old Dynex (dumb) TV as well as a newer TCL Roku Smart TV w/ soundbar.
Question is, can I access Roku data as used to be provided by ECP queries like '/query/apps' and '/query/active-app' via the Roku's USB port? ...if not, what is required to accomplish this end?
Answer: The definitive answer from the Roku folks is no. It's use is for data storage devices.


Why do I have a urine smell under vanity in bathroom

Question: I live in a condo & under my vanity it smells like urine which makes the whole bathroom smell like urine. Why & how to get rid of this!!  My cabinet is wood & I've clean with lysol but still smells. Toilet no smell just under my sink inside vanity. Please help
Comment: Do you have a pet?
Comment: I had a sink with a totally corroded  drain assembly. The old guy who lived there used a urinal bottle to keep from having to risk falling going to pee at night. Guess where that bottle got dumped every morning?  This caused a slow leak that accumulated in cabinet floor . Only option was replace cabinet and under it do a helluva clean up and then seal the floor . Maybe previous owner was doing the same at your condo. Or a cat litter box was kept in the cabinet  lol
Answer: This may be a case of mold or mildew which can emit a urine like smell.
I lived in a lower level apartment for a time that was overly humid and this urine smell would crop up in enclosed areas or behind furniture from time to time.
In this case you need to ensure you improve ventilation/airflow in the affected areas, to stop the mold problem from getting worse.
Once you have better airflow, you can deal with the scent by putting vinegar in a spray bottle and lightly misting all the affected surfaces. Let the vinegar dry, then wipe down the surfaces with a rag and warm soapy water. If the smell persists, make a solution of baking soda dissolved in water and mist all the surfaces with that. Once again let it dry before wiping up. Be sure not to get it too wet, dampness is the enemy.  You can repeat the whole process a few times if the smell is particularly strong/persistent.
in my experience this process got rid of the odor, but if you haven't fixed the overall humidity issue the problem will keep coming back.
Also, if the cabinet is made of particle board and the problem is longstanding, the scent may have permeated the entire thing and be really hard to eliminate.
Answer: The first thing that comes to mind is a leaking toilet seal.  This allows sewage to seep into the subfloor and as the water evaporates the urine gets concentrated and smells.  (I know this from personal experience and it's nasty!)
I had to remove the toilet, tear up the vinyl floor covering, tear out the contaminated subfloor, and replace them all with a new toilet seal.  The floor joists were not affected so I didn't replace them.
It could also be a problem with the sink trap under the vanity but generally that smells like feces instead of urine.


Raycast a ray to the tip of another ray

Question: I'm using unity to raycast a line from the center of my camera viewport to a world position (yellow line).
I also want to cast a ray from the center of my character to this same point (blue line).
I have tried two methods to get this to work, however neither has worked.
The two methods are the following:
<code>        if (Input.GetKey (KeyCode.Mouse0)) { //if left click is held down

        Ray crosshairPoint = viewCamera.ViewportPointToRay (new Vector3(0.5f, 0.5f, 0.0f));
        Vector3 crosshairEnd = (crosshairPoint.origin + crosshairPoint.direction * 15);
        Debug.DrawRay (crosshairPoint.origin, crosshairPoint.direction * 20, Color.yellow, Time.deltaTime, false);
        Vector3 intersect = crosshairPoint.GetPoint (20);
        Debug.DrawRay (Vector3.zero, intersect, Color.red, Time.deltaTime, false);

        Debug.DrawRay(_charFace.position, intersect, Color.cyan, Time.deltaTime, false);

    }
</code>
The red line being drawn is a line from the origin, which has no problem intersecting my camera ray line. The one from my character just refuses to point at the given point.
The second method is the same as above, but using vector math (origin + direction * distance) to get the same point.
Any ideas why the ray from my character won't point the right way, but one from the origin would? Something to do with world vs. local coordinates?
Thanks]1
Answer: I ended up using Physics.linecast from the _charface.transform.position to the intersect point.

Raycast a ray to the tip of another ray


Deploying a Web.py application with WSGI, several servers

Question: I've created a web.py application, and now that it is ready to be deployed, I want to run in not on web.py's built-in webserver. I want to be able to run it on different webservers, Apache or IIS, without having to change my application code. This is where WSGI is supposed to come in, if I understand it correctly.
However, I don't understand what exacly I have to do to make my application deployable on a WSGI server? Most examples assume you are using Pylons/Django/other-framework, on which you simply run some magic command which fixes everything for you.
From what I understand of the (quite brief) web.py documentation, instead of running web.application(...).run(), I should use web.application(...).wsgifunc(). And then what?
Answer: Exactly what you need to do to host it with a specific WSGI hosting mechanism varies with the server.
For the case of Apache/mod_wsgi and Phusion Passenger, you just need to provide a WSGI script file which contains an object called 'application'. For web.py 0.2, this is the result of calling web.wsgifunc() with appropriate arguments. For web.py 0.3, you instead use wsgifunc() member function of object returned by web.application(). For details of these see mod_wsgi documentation:
http://code.google.com/p/modwsgi/wiki/IntegrationWithWebPy
If instead you are having to use FASTCGI, SCGI or AJP adapters for a server such as Lighttpd, nginx or Cherokee, then you need to use 'flup' package to provide a bridge between those language agnostic interfaces and WSGI. This involves calling a flup function with the same WSGI application object above that something like mod_wsgi or Phusion Passenger would use directly without the need for a bridge. For details of this see:
http://trac.saddi.com/flup/wiki/FlupServers
Important thing is to structure your web application so that it is in its own self contained set of modules. To work with a particular server, then create a separate script file as necessary to bridge between what that server requires and your application code. Your application code should always be outside of the web server document directory and only the script file that acts as bridge would be in server document directory if appropriate.
Comment: Ok, so there is no general way to do it. Pity. I'll just have to write up a bunch of adaptors then.
Thanks anyway!
Answer: As of July 21 2009, there is a much fuller installation guide at the webpy install site, that discusses flup, fastcgi, apache and more.  I haven't yet tried it, but it seems like it's much more detailed.
Answer: Here is an example of two hosted apps using cherrypy wsgi server:

#!/usr/bin/python
from web import wsgiserver
import web

# webpy wsgi app
urls = (
  '/test.*', 'index'
)

class index:
    def GET(self):
        web.header("content-type", "text/html")
        return "Hello, world1!"

application = web.application(urls, globals(), autoreload=False).wsgifunc()

# generic wsgi app
def my_blog_app(environ, start_response):
    status = '200 OK'
    response_headers = [('Content-type','text/plain')]
    start_response(status, response_headers)
    return ['Hello world! - blog\n']

"""
# single hosted app
server = wsgiserver.CherryPyWSGIServer(
            ('0.0.0.0', 8070), application,
            server_name='www.cherrypy.example')

"""

# multiple hosted apps with WSGIPathInfoDispatcher
d = wsgiserver.WSGIPathInfoDispatcher({'/test': application, '/blog': my_blog_app})
server = wsgiserver.CherryPyWSGIServer(('0.0.0.0', 8070), d)
server.start()


I want to change the url for mobile user to m.mysite.com with same mobile view look in browser

Question: I need my site www.mySITE.com to open as m.mySITE.com on mobile devices. It has SSL set up also. Please share the code and file name as I do not have any coding knowledge.I want to display the same theme as it is looks like now, only need to change the url.
Answer: Can you please specify which version of Magento you are using?
What is your end goal with this mobile version of the site if the theme is going to be the same?
You can setup JS redirects based on browser-type. I would start with adding a new store-view under your current store. This is where you can specify the new domain to use (replacing WWW with SUBDOMAIN). Keep in mind you'll need to ensure your cookie settings include this subdomain for both store-views and you'll want to test and make sure that the shopping cart is able to carry products between these views as well.


How can women live without Testosterone

Question: I read that men experience degraded fitness under testosterone deficiency. There are ways to support it in norm. But what about the woman. How can they stay so vivid at much lower testosterone levels? Do they have different (muscle/brain) tissue responsiveness to the testosterone?
Comment: An interesting inquiry, but doesn't seem to be on topic re specific fitness questions/problems.
Answer: I'd like to clarify a very important point: both men and women have testosterone and estrogen, however the proportions and functions are different in each.  An article on whether "BioSignature" holds water against science had some interesting facts regarding the role of testosterone and estrogen in men and women:

In men, testosterone is the primary counterbalance to cortosol.  Additionally, the body will manufacture the estrogen it needs from testosterone.
In women, estrogen is the primary counterbalance to corotosol.  Additionally, the body will manufacture the testosterone it needs from estrogen.

The hormonal profile between men and women are different, and the effect they have on the body is profound.

Women tend to handle endurance better than men
Men tend to handle tasks that require more power output (i.e. moving heavy objects, etc.)

NOTE: women also have skeletal differences that do affect the weight they can handle, and what constitutes proper form.
There are some similarities as well:

Muscle behaves the same in men and women.  Given the same cross-sectional mass of muscle, and the same neural efficiency, men and women will be able to move the same weight.  The hormonal differences prevent a woman from gaining the same cross-sectional mass of muscle with the same duration and quality of training.
Women can, and should, train in much the same way as men do.  Certain movements will be easier to progress in than others.  For example, pressing is more difficult compared to deadlifting for women.

Bottom line is this: both men and women's physiologies are fundamentally different.  Women simply don't need the same amount of testosterone as men to function properly from a physiological standpoint.  They aren't going to develop the same moodiness, lack of sleep, depression, and other ailments common with low testosterone in men.  Also note that all a "natural testosterone booster" can do is bring low testosterone closer to normal levels.
Comment: In summary, you say that they can because they can. This is a bit circular argument (I did not get how cortosol, ednurance, power and muscle/skeletal differences allow to women to maintain fitness at lower testosterone levels). Yet, compared with the first answer, it is a wisdom itself.
Comment: The body will manufacture the testosterone it needs.  Men and women are physiologically different, and the body's requirements for the hormones in question are different.  I hope that much is clear.  If you are asking why men and women are different that's a fundamentally different question not suited for a fitness focused Q&A site.
Comment: @Berin Loritsch, could you please forward me a link of how to boost testosterone naturally. Sine I have so many contradict natural foods.

How can women live without Testosterone


What determines the maximum ground speed of hot air balloons?

Question: I am wondering how the ground speed of hot air balloons is controlled. The wind is obviously going to have a large influence upon the ground speed, but apart from wind effects, do hot air balloons have the ability to control their ground speed? If so, how? Is there a maximum limit to the ground speed of a hot air balloon? What factors contribute to this speed limit?
Comment: The wind doesn't just "have a large influence", it is the one and only determining factor.
Comment: Voting to reopen. The "duplicate" question is certainly related, but the answers there do not, in fact, answer this question, which is much more basic and fundamental.
Comment: Wow, 4 answers to chose from.  I would have accepted @expeditedescent's comment.
Answer: Balloons travel with the wind, so all their motion over ground comes from air movements.

do hot air balloons have the ability to control their ground speed? If so, how?

This was a burning question in the nineteenth century and many attempts were made to influence ground speed, apart from rising into higher altitudes and testing whether the wind direction there is different. Naive people added sails but had to notice that those remained limp and only added weight. Others added paddles or engines (steam, electric and gasoline engines were tried) but success was limited before Zeppelins started to make directed lighter-than-air travel routine.
An interesting variety was tried by the Swedish balloonist Salomon August Andrée who added three long ropes to his balloon, their ends dragging on the ground. This caused drag which slowed the balloon, thus giving it some speed difference versus the wind. Now, with some relative wind, sails could indeed generate a force which could move the balloon sideways. However, when tried in 1897, two of the ropes were lost during launch and the remaining one proved ineffective.

Andrèe's balloon (picture source)

Is there a maximum limit to the ground speed of a hot air balloon?

No, if the balloon rises into the jet stream, it can travel at several hundred miles per hour. There is no speed limit once the balloon is up in the air.
However, filling and launching the balloon requires calm winds; hot air balloons almost never start in winds higher than 10 miler per hour. Landing in higher winds becomes dangerous, so here also a calm wind is preferred.

What factors contribute to this speed limit?

This is not about ground speed limits, but wind speed limits: While there is no fixed limit, higher winds will prevent the envelope to stretch out completely and rise up when being prepared for launch. Instead, the windward side will remain dented. During landing, the gondola will be dragged along on the ground when wind is too high. Both these factors let balloonists prefer calmer wind for take-off and landing. Once the balloon is up in the air, no such limit exists any more.
Answer: A hot air balloon has no means of (horizontal) propulsion. As such, it will not move relative to the surrounding medium (the air). If the air moves relative to the ground (wind), the balloon will remain stationary relative to the air, and thus also move over the ground.
In other words, if the wind is blowing at 10 knots, the balloon will have a ground speed of 10 knots. If the wind is blowing at 200 knots, the balloon will have a ground speed of 200 knots. Regardless, from the perspective of the balloon, it will be stationary (relative to the air).
Answer: An ordinary hot-air balloon drifts with the wind and so its ground speed is always that of the wind.
Some control over flight direction is possible by knowing or guessing the wind direction at different altitudes and climbing or descending to a level where the wind is favourable.
A hot-air "dirigible balloon" or airship has an engine and propeller. But they have been few and far between, I don't know if any are still flying.
Comment: How does the balloonist know the wind direction at different altitudes in advance?
Comment: Specialist weather forecasts are often available. As you go up through the levels, you take note. Clouds or birds at different heights sometimes give clues. Experience of wind conditions and knowledge of meteorology also help, But it is far from an exact science. On a competition flight, the unlucky or less skilled competitors may end up way off target.
Answer: pretty much answered that we go the speed of the wind but I dont think it was mentioned that air speed can vary by altitude not just direction but also speed.  you may have higher winds on the ground and come to a complete stop higher up.   or there may be a fast layer.  and as such you can punch through that layer and not allow yourself to completely get up to the speed of that layer.  balloons are several thousand pounds of mass, essentially weigh more than most cars.  it takes a while for the air to change the direction of that mass.   The basket can be in a different layer than the equator and you will feel that wind on your face or body as the larger part of the envelope has the most drag and really determines the speed.
with experience you can punch down into a fast layer on the ground and land before completely getting up to that speed.  at the same time depending on what and where you are landing a long drag on the ground is okay.  Also depending on your balloon and experience you can dump the air out, esp on higher wind landings very fast, top fully open or a cap top that is fully open as the balloon tips over that ball of heat mostly exits the balloon.
You can also do things like rub the ground or rub trees to slow down but this has its own experience and risks involved, generally not something you do.
but as everyone has answered, most of the time, you are going at the speed and direction of the wind that is around the balloon.
Answer: The only horizontal forces which act on hot air ballons are that of drag because of wind. In other words, balloons are pushed around only by wind. There is no other horizontal force (e.g. motor, or other means of propulsion) which act upon the balloon.
This means that as soon as the balloon reaches the wind velocity, it will not feel any other horizontal force. If it slows down/speeds up for some reason, the wind will push it again until it reaches the wind speed.
Therefore: The ground speed of the balloon is always that of the wind.
As a side note: Balloons exploit the fact that at different altitudes the wind blows in different directions and at different strengths. By flying at different altitudes, the ballon can use the different directions of the wind to reach its destination.


automate PDF presentation changes file to 72 dpi, I need it to remain at 300 dpi

Question: I want to save individual PS6 files into one PDF to upload to kindle to create a book.
My images in PS6 are all 8"x6" @ 300dpi.  When I automate PDF presentation, no matter how I save it, the newly created PDF document becomes 72dpi.  If it keeps the 8" x 6" the file downsizes to 576 x432. (72dpi)
Even if I save without compression it will
keep the 2400 x 1800 but changes the document to 33.34 x 25". (72dpi)
Please help!!  I need to keep the physical size to 8" x 6" but need the 300 dpi resolution
Comment: You should show what does and with what command and settings it does the actual "automated PDF presentation" Nobody can tell anything else than guesses if you keep the essentials secret.
Answer: There is no option to set the images resolution with the automate PDF presentation.
I suggest you create an action "Save as PDF" where you will be able to set the image quality :
Window > Actions (create an action and record your steps)
Then you can do a batch treatment with your action on all your psd files :
File > Automate > Batch (and select your feshly created action)
All your PSD files will be converted into PDF 300dpi files, then you will have to assemble them with Acrobat or another app.


Take screenshots without power button

Question: I have an iPhone 5s that I got from a friend & the power button is extremely hard, next to impossible to push is. Is there another way I can take screenshots?
Answer: You can use Assistive Touch. Enable it from Settings → General → Accessibility → Assistive Touch, then to take a screenshot you can tap the Assistive Touch button and choose Device → More → Screenshot. The menus can be customised in Settings to provide easier access to the function if you use it often.

Take screenshots without power button


The difference between adding 第 and 次 to numbers

Question: Both 第 (prefix) and 次 (suffix) both seem to have the effect of turning it into an ordinal (eg: "two" into "second"). And sometimes they are both used, like 第二次大戦. When does one choose one over the other, or choose both? How do they compare/contrast?
Comment: Related https://japanese.stackexchange.com/q/14915/45489
Comment: Does this answer your question? [Using 次 as a counter](https://japanese.stackexchange.com/questions/14915/using-%e6%ac%a1-as-a-counter)
Answer: 次 is a counter/unit with specific meanings. It's used in three types of situations:

Counting or numbering phases, waves of one big phenomenon/event. 次 tends to be used for things that happen randomly but eventually finish, whereas 回 is used for regularly scheduled events and programs.

3次販売 third sale (of a popular product)
2次災害 secondary disaster
攻撃は4次に分けて行われる Attacks will be done in four waves.

(Math) Counting a degree of a polynomial.

3次関数 cubic function
2次方程式 quadratic equation

Saying primary, secondary, tertiary, and so on to describe the order of importance (3次 and larger are uncommon)

2次的な目的 secondary purpose
廃熱の2次利用 secondary utilization of waste heat

As for 第1/2次世界大戦, I think 次 was used because the two World Wars were considered to be parts of a larger historical process.
On the other hand, 第 is just like "no." or "-th".

第3会議室 Conference Room 3
第4開発部 Development Division IV
交響曲第5 Symphony No. 5
第3王女 Third Princess

Its primary purpose is to make an ordinal/label and avoid confusion (3会議室 would mean "three conference rooms"). 第 is common in stiff fixed phrases such as 第2次世界大戦. But since there is usually no ambiguity when 次 is present, it's often safe to drop 第; for example, 3次販売 and 第3次販売 are interchangeable.
Answer: There is no conflict, and 第二次 simply means 'the second time'. 第二 means the second and 次 means time.
Yes it's possible to say 第二大戦 to mean 'the second war', but most people would interpret it as 'the second (the inferior) war, the war that is the second in class', implying there is a 'greater war'.
Such is the habit of the Japanese (or Chinese, since this is Kango) language, to say 'the second time 第二次' instead of 'the second 第二'.


If Mg(OH)2 is insoluble, why does the reaction of MgO and water produce a slightly alkali solution?

Question: The equation of the reaction is:
Mg(OH)2 + H2O -> Mg(OH)2.
Why is it that this reaction produces a solution of around pH 9? There are no OH- ions produced.
Comment: That is not the definition of "insoluble."
Comment: There are lots of hydroxide ions produced.  Most of them are reprecipitated as solid magnesium hydroxide.  Magnesia is not only a base in water, but a moderately strong one.
Answer: As you noted
$$\ce{MgO + H2O -> Mg(OH)2}$$
but the Magnesium Hydroxide is not totally insoluble.
$$\ce{Mg(OH)2 <=> Mg^2+ + 2 OH-}\tag{1}$$
$$\mathrm{K}_{\mathrm{sp}} = 5.61\times10^{-12}= \ce{[Mg^2+][OH-]^2}\tag{2}$$
The dissolution of $\ce{OH-}$ from the $\ce{Mg(OH)2}$ is in equilibrium with the autodissociation of water:
$$\ce{H+ + OH- <=> H2O}\tag{3}$$
with
$$\mathrm{K}_\mathrm{w} = 1.00\cdot10^{-14} = \ce{[H+][OH-]}\tag{4}$$

We will ignore $\ce{CO2}$ from the atmosphere making $\ce{CO3^{2-}}$...

Let's assume that a "considerable" amount of $\ce{Mg(OH)2}$ dissolves, but not all, so that we can ignore the initial amount of $\ce{H^+ \text{ and }OH-}$ from the autoionization of the pure water. Then using $\ce{[OH-] = 2[Mg^{2+}]}$ we can substitute into equation (1) for $\ce{[OH-]}$ and get
$$\ce{[Mg^{2+}]} = \sqrt[3]{\dfrac{5.61\times10^{-12}}{4}} = 1.1194\cdot10^{-4}\tag{5}$$
which means that
$$\ce{[OH-]} = 2\times1.1194\cdot10^{-4} = 2.2388\cdot10^{-4}\tag{6}$$
This is basic enough that the autodissociation of water can be ignored, so our assumption was valid. We can calculate $\ce{[H+]}$ from equation (4):
$$\ce{[H+]} = \dfrac{1.00\cdot10^{-14}}{\ce{[OH-]}} = \dfrac{1.00\cdot10^{-14}}{2.2388\cdot10^{-4}} = 4.4667\cdot10^{-11}$$
and
$$\mathrm{pH} = -\log{(4.4667\cdot10^{-11})} = 10.35002 \ce{->[Rounding]} 10.350$$
Answer: Because Ksp of Mg(OH)2 is not zero !
First of all understand that solubility (diffusion of ions from solid to liquid phase) has some equilibrium constant. And that K (eq.constant ) of any reaction can't equal zero. So, for this small but finite K, some ions Mg and OH diffuse into the water and make the solution Alkaline !
Answer: An insoluble base means that the compound $\ce{XOH}$ remains as its own phase (usually solid) in the medium, while some of it dissolves in the water as $\ce{X+}$ and $\ce{OH-}$. In this case, the $pH$ of the medium is dictated by the solubility product ($K_s = [\ce{X+}][\ce{OH-}]$), instead of the acid/base constant as for something like $\ce{NH3}$ - where both itself and its conjugated acid $\ce{NH4+}$ exist in solution and in equilibrium and the $pH$ will be defined by the relation $K_b = \frac{[\ce{NH4+}][\ce{OH-}]}{[\ce{NH3}]}$. Note that because the base itself is insoluble, it does not appear in the equilibrium constant because it has no chemical activity in the aqueous medium.
In a complete counter scenario, something like $\ce{NaOH}$ is considered a soluble base, but in this case the conversion into ionic species in solution is total, hence the base is also considered strong. For those, the pH is controlled by the concentration of the base itself ($pH = 14 - pOH$ with $pOH = -\log([\ce{NaOH}]$).
All the considerations above of "pH determination" are valid for systems where the base is the only solute in water.


Does a Canadian, resident in the USA, need travel health insurance in Canada?

Question: My girlfriend will be visiting Canada for about a month. Should we get health insurance? Is she covered in Canada?
Comment: Depends whether her current insurance covers external providers and what your risk profile is. Always safest to get travel insurance just to be on the safe side. It covers emergency evacuation, lost baggage, and more.
Comment: If you're asking if she has any coverage from Canada or its provinces, the answer is no.  Only residents get public health care benefits in Canada.  She'll need to buy insurance in the US to cover her in Canada, unless her existing health insurance is valid there and has adequate coverage.
Answer: Insurance is about trading risk. If you feel it is needed to avoid worrying, then make sure she has some.
Canadian public insurance which varies by province is based on residency and so it is unlike that she will be covered by it. In Quebec for example, you have to reside 183 days per year to be covered. The rules are rather complex and there are exceptions such as while studying abroad.
She may be covered by insurance from the US already. There is usually a clause in health insurance that covers someone for a certain number of days outside of the country. It is usually a few weeks but that depends. Read the fine print of her insurance plan. Some credit-cards also add travel insurance, including health, when buying the full-price of the ticket with that card. Again, read the fine print.
Comment: She certainly won't be covered by any provincial or territorial plan in Canada.  Not only must she be resident, but there is a delay after taking residency and applying for coverage before coverage begins.
Answer: First, check to see if she is covered under her US insurance (if she has any).
Many, but not all, US health insurance plans will provide coverage abroad. I'd check the fine print of the policy to see what coverage is offered and if it is adequate.


What is the procedure for mas'h (wiping) over sock/shoes, etc.?

Question: Assalamualikum.
I wish to know the method of doing mas'h (wiping over) socks or shoes, etc. Especially, how do I enter into a state wherein I can perform mas'h. Also, can I perform mas'h over cotton or nylon socks?
Comment: @BleedingFingers : to do mash! what other purpose. I'm a frequent traveler so I believe that I may benefit from this sunnah :)
Comment: Elaborate for what purpose you want to do the Mash?
Answer: "MasH" مَسْح in Arabic means to wipe, to rub, to wash, to clean, or to mop.
I will use washing or wiping, since these are more popular.
The ruling on MasH is legalized by Allah in Surah al-Ma'idah 5:6 =
يَا أَيُّهَا الَّذِينَ آمَنُوا إِذَا قُمْتُمْ إِلَى الصَّلَاةِ فَاغْسِلُوا وُجُوهَكُمْ وَأَيْدِيَكُمْ إِلَى الْمَرَافِقِ وَامْسَحُوا بِرُءُوسِكُمْ وَأَرْجُلَكُمْ إِلَى الْكَعْبَيْنِ
O you who have believed, when you rise to prayer, wash your faces and your forearms to the elbows and wipe over your heads and your feet to the ankles...
The words "waArjolikom ilAlka'Abayni" gives us the legality of wiping or washing our feet up to our ankles because it's connected with "wa" to the previous description of MasH on head.
It's important to mention that this verse can be recited in TWO DIFFERENT ways.  Both ways come directly from Rasolullah's teachings.  This has nothing to do with Sunni or Shi'a ways.  It's about Allah and the Prophet.
First way, is reciting it "waArjilikom" with kasra on lam, which links it back to "your heads," hence, legalizing wiping of feet.
Second second, is reciting it "waArjolikom" with fatha on lam, which links it back to "your forearms to elbows," hence, legalizing washing of feet.
Imaam at-Tabari in his tafsir of this ayah, says that both washing or wiping our feet is ACCEPTABLE because both recitations are from Allah.  So, no one can claim one is better than the other.  Otherwise, they would be rejecting the Quran one way or another.  Both ways are acceptable.
Now, HOW do we do masH?
Since the ayah in Surah al-Ma'idah 5:6 is referring to feet.  We must have done wudhu before putting anything on our feet.
The ayah doesn't legalize wearing anything before wudhu because of "waArjolikom" or "waArjilikom" - literally in Arabic it means "and your feet" i.e. barefoot, nothing on your skin.
Once we have done wudhu, then we put on our footwear. But the footwear must be up to our ankles as wiping is permitted up to that.
I specifically used the word "footwear," as anything that's considered as footwear is acceptable.
No matter what the footwear is from, whether cotton, leather, wool, or even made out of wood or leaves. It's still considered footwear and the general rule of wiping applies to all.
Another way to prove that the wudhu must be done prior to making wudhu is an authentically proven hadith from 'Orwa bin al-Moghira from his father al-Moghira saying=
"One night I was out wondering around with the Prophet. He said to me: "Do you have any water?" I said: Yes. He came off from his camel and went on until he disappeared in the darkness of night. He then came back and I poured water for him from the jar.
He washed his face. He had a woolen gown on him and he could not bring out his forearms from it. So he brought them out from under his gown. He washed his forearms, wiped over his head. I went to take off his Khuffayn. But he said: Leave them, I put them on pure." and did masH over them."
The wording is from Imam Muslim's collection as the narrators were more clearer in reporting it = حَدَّثَنَا مُحَمَّدُ بْنُ عَبْدِ اللَّهِ بْنِ نُمَيْرٍ، حَدَّثَنَا أَبِي، حَدَّثَنَا زَكَرِيَّاءُ، عَنْ عَامِرٍ، قَالَ أَخْبَرَنِي عُرْوَةُ بْنُ الْمُغِيرَةِ، عَنْ أَبِيهِ
Summary=

Surah al-Maidah 5:6 obligates wudhu before prayer and permits wiping or washing the feet.
Anything that's considered footwear is allowed, since there's no evidence restricting the generality of the verse or saying related to Rasolullah.
Rasolullah demonstrated that he was pure prior to putting on his khuffayn, therefore, he did masH over them and didn't take them off.
Him doing wudhu shows he had broken is wudhu.

Allaho alim.
Comment: It's in Sahih Muslim, under Book of Purification.  It's also in Sahih al-Bukhari under Book of Wudhu and Book of Dress.  All the narrators were trustworthy and reliable.
Comment: MashAllah a fantastic answer! Where is the hadith recorded as authentic/sahih?
Comment: "The wording is from Imaam Muslim's collection as the narrators were more clearer in reporting it = حَدَّثَنَا مُحَمَّدُ بْنُ عَبْدِ اللَّهِ بْنِ نُمَيْرٍ، حَدَّثَنَا أَبِي، حَدَّثَنَا زَكَرِيَّاءُ، عَنْ عَامِرٍ، قَالَ أَخْبَرَنِي عُرْوَةُ بْنُ الْمُغِيرَةِ، عَنْ أَبِيهِ
Comment: Sayyid, you know you can edit your answer don't you?
Answer: First of all, this is debatable between Sunni and Shia .
5:6 يَا أَيُّهَا الَّذِينَ آمَنُوا إِذَا قُمْتُمْ إِلَى الصَّلَاةِ فَاغْسِلُوا وُجُوهَكُمْ وَأَيْدِيَكُمْ إِلَى الْمَرَافِقِ وَامْسَحُوا بِرُءُوسِكُمْ وَأَرْجُلَكُمْ إِلَى الْكَعْبَيْنِ ۚ
Sunni says that you must wash your feet while Shia said that wipe on your feet is what needed.
And every sect has their proves. I'm not going to insert these talks but for your answer because the initial different is in Arabic language whether the conjunction letter و in  وَأَرْجُلَكُمْ refer to the  وامسحوا which means wipe as Shia says or whether refers to فاغسلوا as Sunni says.
If you are Shia then there is no problem since Shia is already says to wipe over feet and not wash. But for wiping over coton or nylon socks, this is forbidden by most of the Marajeaa but some of them said you can do that as you can be sure that the wet will reach your feet and since this will not happen then it's forbidden. and there is another case when one feels from disease or other unusual big fear

مسألة 97: لا يجزي المسح على الحائل ــ كالخف والجورب ــ لغير ضرورة بل
  يشكل أيضاً الاجتزاء به مع الضرورة في غير حال التقية الخوفية، فلا يترك
  الاحتياط حينئذٍ بضم التيمم، وأما في حال التقية فيجتزئ به وإن كان
  الاحتياط في محله.
http://www.sistani.org/arabic/book/23720/3603/

This means:
You are forbidden to wipe over anything other than your foot skin unless there is a great damage for you
Comment: Could you please improve this answer? It's an OK start, but lacks detail and references.
Answer: The procedure is simple. First do the complete wudhu (as prescribed in the Sunnah) and then wear your socks (in the state of wudhu). The socks must cover the ankles. So if you're travelling or in a public place and it is difficult to wash your feet, one can perform mash (i.e. gently wiping over your socks (top part) with wet hands).
Comment: It would be better to mention your sources and proof.


Recording activities - case or contact summary page?

Question: Is it better practice to record activities in the case rather than on the contact summary?  If so, why?
Comment: Hi Kate. You may like to know that I'm currently working on a new feature for CiviCRM that would enable you to see Case Activities on the normal Contact Activities listing. This way you can use Case Activities, but not lose the benefits of being able to see all of someone's activities in one place. You can [read more](https://github.com/civicrm/civicrm-core/pull/16360) - it's not something that's ready yet, though, but hopefully in a future release of CiviCRM.
Answer: Kate, Welcome to CiviCRM stack exchange. About your question, it depends upon your business logic. If you want the activity to be part of the case than you should create them inside a case since the New Activity form from the Contact summary page doesn't provide ability to add activity to case. You can but obvious move the activity later after creating by using Move to case link or Move to case from task action.
If you don't want activity to be part of the case than you should use option from Contact Summary screen.
Thanks
Pradeep
Answer: If the activity relates to the Case, then create it there but otherwise just on the Contact.
For example, if you have a case for managing volunteer onboarding, then a meeting relating to onboarding would be a case activity but a phone call about a donation would be a simple contact activity.


Difference between applying voltage, and voltage across?

Question: I'm confused about the two terms, when voltage is applied and across a certain element in the circuit.
Comment: @IgnacioVazquez-Abrams If you connect the diode in reverse, wouldn't the voltage across it be 5V?
Comment: You can apply 5V to a silicon diode, but the voltage across it will be 0.6V regardless.
Comment: Yes, it would... But that's because for "low" voltages a reverse biased diode equals an open circuit
Comment: @IgnacioVazquez-Abrams why does the term voltage across matter? "it" being what in your statement?
Answer: What Ignacio said is the core of the answer, I hope I can help you out going a bit deeper.
Generally the only distinction between "applied voltage" and "voltage across" is how you are dealing with voltage itself:

you apply a voltage to a bipole taking a voltage source and putting it in parallel with the dipole.
you usually measure a voltage across some dipole, putting a voltmeter in parallel with it.

That's to answer your question. Now what if you apply a voltage generator? What would the voltage across it? The answer is: there is no answer. That is a limitation of the model we are using. Ignazio makes the useful example of a diode: you apply 5V but across it there's only something like 0.7V: that's because your voltage source has an internal resistance where the remaining 4.3V drops.
Remember that most of the times when you apply a voltage to a dipole, the voltage across it will be exactly what you are applying. The two wordings though does not mean the same thing at all.
addendum
Since this is at the top now, and I've read some others very good answers, and since the question is very basic I'd like to add two words about potential, a word that every answer uses. A potential is a scalar field associated with a vector field. This vector field must be conservative for the potential to exist, and for the electric field this is true only for electrostatic fields. When things start moving around no potential can be defined. I don't want to be the fussy physicist but a professor once throw a chalk at me for this imprecision (he was quite precise) so since this might be seen from young students I though this should be pointed out.
Comment: To be sure, I find your addendum odd and not contextually correct.  There *is*, for example, a potential difference between the terminals of a resistor with a current through since there is a charge distribution through the resistor that gives rise to an electric field through the resistor.  A charge moving through the resistor loses potential energy.  Moreover, one of the assumptions of ideal circuit theory is that any changing magnetic fields threading the circuit are *insignificant* and thus, potentials are well defined.
Comment: @AlfredCentauri well my point is only the misuse of the word "potential". At least in italian it means a very precise thing that can not be defined for varying E fields. I'd like to see some literature about the fact that this is an assumption, maybe we're speaking of two different things.
Comment: We might be talking about different things so I'll look some references up and see if we can clear things up.
Comment: That's what I am speaking about: [here](http://en.wikipedia.org/wiki/Electric_potential#Generalization_to_electrodynamics). I am not arguing the fact that the word "potential" is widely used in EE, I'm just saying that it might be something that a university physics teacher wouldn't want to hear without the word electrostatic in the same sentence. That's why I'm surprised that the existance of a potential is an assumption for circuit theory, since circuit theory works in AC too of course.
Comment: Like you, I'm aware that an electric potential can only be *strictly* defined for a static electric field.  However, in ideal circuit theory, we *assume* (1) changes propagate instantly (lumped element approximation), (2) no charge accumulates anywhere in the circuit, and (3) there is no magnetic coupling *between* circuit elements.  Of course, this is not physical but, when rates of change are 'small enough' such that the assumptions above are *effectively* true, ideal circuit theory is a *good* approximation.  And, as you're aware, these assumptions *aren't* good for, e.g., RF circuits.
Comment: @AlfredCentauri I agree on each bit of what you wrote, but I still don't see where the "strictly defined" potential is needed in these hypothesis nor what bad can happen if you don't have it at your disposal. I mean, to define a voltage difference you don't need a potential... This whole thing just started on an excessively pedantic observation though, my intention was only to help...
Answer: A voltage is always across two nodes, it is the difference between the electric potentials of these two nodes. They are strictly speaking always applied by something, but we speak about applying a voltage across two nodes when we set the potentials of those two nodes by connecting them to the outputs of a voltage source, which role is to make sure the voltage across those is fixed to a known value.
The voltage of a node is often a shorthand for the potential of that node with respect to the ground of the circuit (which, as a reminder, is only a node which has been arbitrarily associated to a 0V value).
Electric potential is often compared to height in the liquid analogy where the flow of water is electric current and rocks along its path, resistance.
Reminder: a node is a uniquely defined point of interest in the circuit (a pin, the intersection of several branches etc.).
Answer: The phrase "voltage across a circuit element" means precisely the potential difference between the terminals of the circuit element.  One can measure this voltage with a meter.
The phrase "voltage applied to a circuit element" is less precise but I believe it means that one is driving the circuit element with a voltage source of some type and that the voltage across is, more less, fixed by this source.
The opposite of this would be the "voltage supplied by a circuit element" which would imply that the voltage across is generated by the circuit element, e.g., a battery, a charged capacitor, etc.
Comment: @Key, if the PS is effectively a voltage source (insignificant internal resistance), the PS *fixes* the voltage across the element.  Changing the resistance of the element will only change the current through.  If the PS is effectively a current source (high internal resistance), the PS fixes the current through.  Changing the resistance of the element will only change the voltage across.  If the PS is neither a good voltage source nor a good current source (moderate internal resistance), changing the resistance of the element will change both the voltage across and the current through.
Comment: Lets break this down even more by using an example. So, we can measure a circuit element like a light bulb, and find that the voltage across its terminals to a certain value, yet... the PS can apply a higher/lower value of voltage to that same bulb?
Comment: In a circuit I have an element that's resistance is extremely low, I'd like to increase the resistance so that more voltage can be applied to that element, yet I'm confused because the voltage across that element stays the same regardless of increasing its resistance... hope that makes sense.
Comment: Thank you, there seems to me a be a lot more for me to understand.
Answer: applied voltage means the voltage which is given by us to the component.
voltage across means the voltage which is reduced by the component due to the internal resistance of the component
Answer: Applied voltage to a component is the actual voltage given to the component. Whereas voltage across a component is the voltage drop/voltage dissipated by the component. In both cases, voltage means a difference in electrical potential between two points. It is always between two points as it is only the difference between those two points that produce an electromotive force.
Now, applied voltage to a component and the voltage across a component may or may not be the same value. If you are applying 5 volts to a single resistor circuit, that resistor will get all of the 5 volts as voltage is conserved within a loop (KVL). If you now have 2 resistors in series of equal value, each resistor now gets 2.5 volts of the total 5 volts. Technically, in the latter case, a total of 2.5 volts is applied to the last resistor, and thus the voltage across it is 2.5 volts. However, there exists non-voltage driven components, meaning they're driven by current instead. A diode of any sort is a good example, where you may apply 5 volts to it, but the actual voltage drop may be something around 0.5 volts. In this case, the rest of the voltage is sent back to the source and power will be dissipated by the internal resistance of the source.
Answer: The right way to say it would be apply voltage across something - it sounds more precise. The voltage is a difference in potential between two points. So, when they say apply voltage, they omit the word across, assuming you know between/across which two points. Commonly, this phrase is used to say 'Apply voltage to a circuit', meaning provide power to a circuit, since you know where to connect two wires. Similarly, you can say apply voltage across the circuit, but it might sound somewhat redundant, but more precise. This phrase is rather used to specifically tell between/across which points the voltage should be applied or measured. In both cases it is meant the say the same thing, but might be misunderstood.


How has literature helped archaeology?

Question: Is there a good example case where extant ancient literature has helped understand archaeological findings?
This could mean, for example, a Roman author mentioning a tool and its use, which has helped us identify some archaeological findings that may have otherwise been left unexplained, or perhaps literature has helped locate or identify certain cities.
The question in the title is broad, and I am not looking for an extensive description as whole.
Instead, I am looking for a single good example from ancient Rome or Greece.
Comment: ... have you heard of Troy ? https://en.wikipedia.org/wiki/Troy#Schliemann
Comment: @blagae The city of Troy actually crossed my mind, but I didn't know or quickly find any concrete way literature helped. An answer about that city would be very welcome.
Answer: If you allow the answer to be a bit wider in scope than the question (this is not Physics.SE, and we have this leeway in humanities), and talk about how linguistic evidence in general, not only written or traditionally transmitted evidence, which is the scope of your question, I should mention a book that is considered somewhat controversial among archeologists, but strikes the right chords in me as a linguist.
The book in the spotlight here is: Anthony, David W. The horse, the wheel, and language : how Bronze-Age riders from the Eurasian steppes shaped the modern world. Princeton, N.J: Princeton University Press, 2007. The conventional archeology uses excavated evidence as the first class, and linguistic and other types of evidence are treated as circumstantial. Anthony's approach is exactly the reverse: He puts the linguistic evidence up front, and then beads the physical, unearthed data from the archeology on this string.
Do not get me wrong when I mention a "controversy." Anthony is the first class archeologist, and there is nothing going on even close to the so called "fringe science;" this is just the approach to the evidence that is felt by some archeologists as a quite non-conventional. And to me, his picture of the ancient IE society looks quite compelling.
I am not trying to write this answer to review the book or retell it's story; it's hard to compress a monograph into a SE answer. I just want to mention his approach to the raw data, necessary simplified fo fit it in this format. Suppose you study the archeology of a culture that had words (according to sound linguistics) for "snow" or "bronze"--such that all, or nearly all daughter languages have inherited them . Already (be careful here, looking for parallel borrowings, though), you can start with a quite a strong hypothesis that the culture that spoke that language dwelt far off the equator enough to experience snowy winters, and their metallurgy knew bronze. This essentially excludes populations living in too lower latitudes or not showing archeological traces of bronze metallurgy from being associated with the speakers of the language in question. An example of two main concepts that are unquestionably made in in the daughter vocabularies are the ttile words for horse and wheel. Also, there is a great deal of other literary evidence of linguistic archeology is analyzed by Anthony, such as Rigvedic texts (and this connects it indeed to your question) that proves a very strong connection that archeology of physical things, namely burial practices. This also constitutes a very strong part in his arguments.
I would not personally say that the monograph is very accessible; far from being a pop-sci work, it requires you to dive into the references and learn a lot of things archeological (but as linguist, again, I am distanced far more away from that than the workings of language). But even without that, a claim to the very close match between literary Rigvedic burial prescription to those physically unearthed graves seems to me to be a very compelling evidence of the cultural connection
So even reading the work while skimming about the parts with a deep foray in archeology (which, I admit, could sometimes fly over my linguist's head) is indeed very enlightening.

How has literature helped archaeology?


In Photoshop can you convert a screen layer to a transparent .PNG?

Question: I've always wanted to know how to do this-- basically seperate the flat base color of an image, and save it with transparency to .PNG. The only method I can think of is with selection tools and that gives a really bad result (not the same).
Comment: Its a little unclear what you're asking.  Can you post an example?  Are you trying to take a layer and change the opacity to make it a partial transparent layer??
Answer: No, some of the modes can under some circumstances be applied to the images channel. But screen is
1- (1-a)(1-b)
and can not be replicated without knowing the value of the ubderlying layer beforehand. Which would make using it irrelevant anyway.
The way you do this is by difference key where you chose one channel as alpha and then adjust white point to clear out the background.
Relevant posts for the removal of bg:

How to remove the textured background from a handwritten text document?
Image transparency be calculated automatically from multiple non-transparent samples?


Can one use dollar cost averaging to make money with something highly volatile?

Question: There are things one can buy in the market that fluctuate in value 20% or more a day.  How would one figure out if dollar cost averaging could make one money, based on instruments with large fluctuations like this?  Or perhaps more succinctly, would it and how much?  Note, here the interval of dollar cost averaging might be several hours, so that over a 3 day span of time, one might dollar cost average 10 times, over something that varies approx 20% in a day.
Comment: There are certain options trading strategies that are designed to make money on highly volatile securities.  You might want to look into the strategies listed here: http://www.optiontradingpedia.com/volatile_options_strategies.htm
Comment: Sounds like transaction costs are going to be rather large. How much do you have at stake? How cheaply can you trade?
Comment: DCA is a loosing game in any timeframe.
Answer: As you mentioned in the title, what you're asking about comes down to volatility.  DCA when purchasing stock is one way of dealing with volatility, but it's only profitable if the financial instrument can be sold higher than your sunk costs.  Issues to be concerned with:

The expected value of this financial instrument when you plan to sell it.
How much you can stand to see the aggregate value in this instrument fluctuate
Overtrading (i.e. you loose your expected profits from transaction fees)
The extent that you need to depend on this instrument to defray margin-calls

Example
Let's suppose you're buying a stock listed on the NYSE called FOO (this is a completely fake example).  Over the last six days, the average value of this stock was exactly $1.00Note 1.  Over six trading days you put $100 per day into this stockNote 2:
11 Jan 2012: BUY 86 shares of FOO at $1.15 (Total: $98.90 + $5 Trading Fees)
10 Jan 2012: BUY 121 shares of FOO at $0.82 (Total: $99.22 + $5 Trading Fees)
09 Jan 2012: BUY 83 shares of FOO at $1.20 (Total: $99.60 + $5 Trading Fees)
06 Jan 2012: BUY 125 shares of FOO at $0.80 (Total: $100.00 + $5 Trading Fees)
05 Jan 2012: BUY 84 shares of FOO at $1.18 (Total: $99.12 + $5 Trading Fees)
04 Jan 2012: BUY 117 shares of FOO at $0.85 (Total: $99.45 + $5 Trading Fees)

At market close on January 11th, you have 616 shares of FOO.  You paid $596.29 for it, so your average cost (before fees) is:

$596.29 / 616 = $0.97 per share

Let's look at this including your trading fees:

($596.29 + $30) / 616 = $1.01 per share.

When the market opens on January 12th, the quote on FOO could be anything.  Patents, customer wins, wars, politics, lawsuits, press coverage, etc... could cause the value of FOO to fluctuate.  So, let's just roll with the assumption that past performance is consistent:
Selling FOO at $0.80 nets:

(616 * $0.80 - $5) - ($596.29 + $30) =  $123.49 Loss

Selling FOO at $1.20 nets:

(616 * $1.20 - $5) - ($596.29 + $30) =  $107.90 Profit

Every day that you keep trading FOO, those numbers get bigger (assuming FOO is a constant value).  Also remember, even if FOO never changes its average value and volatility, your recoverable profits shrink with each transaction because you pay $5 in fees for every one.
Speaking from experience, it is very easy to paper trade.  It is a lot harder when you're looking at the ticker all day when FOO has been $0.80 - $0.90 for the past four days (and you're $300 under water on a $1000 portfolio).  Now your mind starts playing nasty games with you.
If you decide to try this, let me give you some free advice:

Only trade with money you don't care about loosing
Do not trade on margin
Look into calculating support and resistance points for this instrument; then buy near support and sell near resistance.  DCA is much better-suited for long-term investing.
Trade with standing stop-loss orderNote 3

Unless you have some research (such as support / resistance information) or data on why FOO is a good buy at this price, let's be honest: you're gambling with DCA, not trading.

END NOTES:

(1.15 + 0.82 + 1.20 + 0.80 + 1.18 + 0.85)/6 = 1.00
Numbers don't add up to $100 each day because you can't buy a fraction of a share.
Calculating the stop-loss is outside the scope of this answer
Comment: @RayK, options add so many other dimensions to this I really can't address it properly here... I'm personally convinced that playing options can sound easy, but the people who calculate their value are a lot better at math than I will be (or dare I say you, unless you have a post-grad degree in statistics).  Q: Can the avg Joe  make a profitable options trade by throwing darts at the board (i.e. DCA)? A: Yes. Q: Can you do it consistently?  A: If you can, quit your day job, but don't hold your breath.  The market isn't a money press, it is a casino.  You need a better edge than random to win.
Comment: Thanks Mike for the detailed example.  The instrument I was looking at using is a deep in the money call option with very little time value (i.e. nearly all intrinsic value), perhaps on GLD or HAL.  These fluctuate a lot more than in your example.  How would your example come out using these, ignoring trading costs for the moment (assuming these are relatively small in comparison)
Answer: if you know when and by how much something will fluctuate, you can always make money. Buy it when it's cheaper and sell it when it's more expensive.
If you just know that it fluctuated a lot recently, then you don't know what it will do next. Most securities that go to zero or go much higher bounce all over the place for a while first.  But you don't know when they'll move decisively lower or higher.
So how could you figure out if you'll make money - you can't know.
DCA will on average make you better off, unless the extra commissions are too high relative to your purchase sizes. But it will in retrospect make you worse off in many particular cases. This is true of many investment disciplines, such as rebalancing. They are all based on averages.
If the volatility is random then on average you can buy more shares when the price is lower using DCA. But when the lowest price turns out to have been on a certain day, you'd have been better off with a single lump sum put in on that day. No way to know in advance.
Degree of volatility shouldn't matter; any fluctuation is enough for DCA or rebalancing to get you ahead, though it's true they get you ahead farther if the fluctuations are larger, since there's then more difference between DCA and a lump purchase.
I think the real reason to do DCA and rebalancing is risk control. They reduce the risk of putting a whole lump sum in on exactly the wrong day. And they can help keep a portfolio growing even if the market is stagnant.
Answer: That doesn't sound like dollar cost averaging. That sounds like a form of day trading. Dollar cost averaging is how most people add money to their 401K, or how they add money to some IRA accounts. You are proposing a form of day trading.
Comment: I believe he still talking about the same principal just on a shorter time scale.
Comment: I used the term dollar cost averaging, because it is a "formula" people understand, rather than repeating that.  Yes, time scale is different.
Answer: Dollar cost averaging is beneficial if you don't have the money to make large investments but are able to add to your holding over time. If you can buy the same monetary amount at regular intervals over time, your average cost per share will be lower than the stock's average value over that time. This won't necessarily get you the best price, but it will get you, on the whole, a good price and will enable you to increase your holdings over time.
If you're doing frequent trading on a highly volatile stock, you don't want to use this method. A better strategy is to buy the dips: Know the range, and place limit orders toward the bottom of the range. Then place limit orders to sell toward the high end of the range. If you do it right, you might be able to build up enough money to buy and sell increasing numbers of shares over time. But like any frequent trader, you'll have to deal with transaction fees; you'll need to be sure the fees don't eat all your profit.


Why does Q click his fingers?

Question: Why does Q click (snap) is fingers whenever he uses his powers? Is there an in-universe reason or is it pure theatrics?
Comment: Because its "snappy"
Comment: Pure theatrics?  Where would you get that idea? I tell ya, you put trial on humanity and makes yourself the judge descending on some bizarre floating throne just once...
Answer: Not ever defined, that I know of, in universe.. but I'd say it's an intentional self-limiting gesture... with near omnipotence and the ability to simply will things into existence, mere thinking could quickly get messy... unless you created some form of action and tied to the concept of 'invoking' your power, at least in your mind... as Xantec points out, they each have some gesture that they use.  Imagine the chaos for a new Q until they learn to do this!  Every stray thought becoming reality!
This is the same reason the Dresden books have wizards use obscure languages for spells.. once you associate a spell and an effect to a word or phrase, you don't want to trigger it accidentally by thinking it.. so pick something you would not think, except for the specific reason.
I suspect the members of the Q continuum could invoke their powers without their personal gesture... but it might take a pretty strong act of will after a few millennia of habit forming.
Comment: This is the best answer.  The chaos was partially explored in TNG 6x06, "True Q" - Amanda Rogers would accidentally create a bunch of puppies when she turned around, when her pets crossed her mind, and so on.
Comment: Looking back, this was actually made into an issue in the Marvel Comics 'Secret Wars'; Doctor Doom gained the power of the Beyonder, and rails as one of his allies for suggesting a way the Heroes could have survive, as he now must watch his thoughts, let a stray one accidentally cause it to become true.  Which, of course, promptly happens.  A self-limiting gesture like the Q use could have prevented such an issue; it gives him a vulnerability if he can't make the gesture, but saves him from his mere thoughts causing havoc.
Comment: Good thinking. This answer is actually supported in the beginning of "True Q," when Amanda unintentionally brings some puppies into existence.
Answer: Because he is a drama queen, and the rest of the Q collective aren't far behind.
Q only appears in human form only when addressing humans.  If Q appears to another race as a member of that race, he does not necessarily have the correct appendages to snap his fingers.  Q knows a making things change with a snap of a finger is an impressive show for humans, and milks it for all he can.
Comment: This is speculation. Q may appear in the John de Lancie form no matter where he goes.
Answer: I don't know if there was ever an in-universe given by the writers, producers or anyone else but the finger snap was likely that individual Q's method of focusing their power; although as has been seen on mutliple occassions the motion isn't strictly necessary. If you watch all of the various Q episodes you'll see that each Q has their own action they perform when they use their powers (single finger snap, double finger snap, hand wave, etc).
Comment: In my answer [here](http://scifi.stackexchange.com/questions/3172/where-does-q-technology-come-from-and-where-did-it-orginate/3177#3177) I postulated that Q-tech responds to mental commands, activated by a physical gesture.  Seems like we think alike.
Comment: When Riker gets Q powers in an episode early in the series, his is a full arm wave. Maybe it's because he's new to his powers or that's just the way it works for him; as was said there was never a reason given.
Comment: @KeithS I got the impression that the full arm wave was kind of overdoing it with an "I'll show you!" expression of emotion.
Answer: It's questionable that the real Q is actually snapping his fingers (or hand waving, or other kinds of fluorishing) - don't forget, we're only seeing a representation of him in this dimensional/existential/plane/thingie.
But, it kind of makes sense - if you were omnipotent, the last thing you want is for stuff to happen as soon as you think it - it would get kind of chaotic (us mere mortals are rather flighty, and I'd imagine an omnipotent being to be more so). So, link it to a physical gesture to enforce the desire for something to happen.
Comment: This would tie in with the Voyager crew entering the Q continuum. They only got a representation of the place.
Answer: Frankly, I think it's just for show. After all, there are certainly occasions in which Q does not snap his fingers, or make any other noticeable movements. At the end of "Encounter at Farpoint," Q leaves without a gesture, and just after commencing the game of Hide and Seek with Amanda Rogers he does the same thing. Amanda also leaves without apparently making any movements ("True Q").
It may be that young Q are taught to do this in order to first definitively establish whatever it is they want to do, so that every stray thought of theirs doesn't immediately become reality. However, for experienced Q, like most of the Q Continuum, it seems that such movements are totally superfluous. Note that in "Q2," Q vanishes after directing a wink toward Captain Janeway. Q most certainly was trying to be showy in that instance!
Answer: In addition to the other excellent answers, I think Q snaps to accentuate the ease at which he uses his powers. The term "it's a snap" refers to something that is very easy to do, like snapping your fingers, so I think this makes sense.

Why does Q click his fingers?


SQL Server Service's Log On As account

Question: I just inherited a set of new servers and whoever set them up left the "Log On As" account as the default "NT Service\MSSQLSERVER". I'd like to change that over to an Active Directory service name. I have never attempted changing it after we have already went live in production. Is there anything I should be aware of? Will it require a restart of the service? This server is only using SQL, not SSIS, SSAS, SSRS. I will make sure the AD service name has access to all the folders necessary to reach files. Anything else I'm missing?
Answer: As long as you change the service account within SQL Server Configuration Manager (SSCM) it will apply all the permissions required (registry, files, etc.).
Only thing to be aware of are those rare occasions where SSCM process does not apply all permissions as expected, generally from some WMI issue. I so far have not come across this in new versions of SQL Server (2008 R2+).
By the name of that service account I am going to assume you are on an OS of Window Server 2008 R2 or higher. Just as a side note, if you do not actually need access to Active Directory resources leaving that account as the system account is perfectly alright. Most security standards will allow it as well if you are running on a current Operating System. These are virtual accounts that offer more security than the previous local system accounts did in previous versions of the OS. They are less chances of someone impersonating those accounts. I use them on most servers I setup for clients now unless they have some reason to need full domain access.
Comment: My understanding is that local accounts like that cannot be granted read/write permissions to shared drives on other servers. That is the problem I'm running into now (along with my assumption that it's best practice to use AD accounts). Can local accounts be granted read/write perms to a shared drive?
Comment: If the computer account is registered on your domain, yes you can. [You would be granting the computer access](https://msdn.microsoft.com/en-us/library/ms143504.aspx#New_Accounts) and not a single account, which some don't like doing. If you don't then just use a domain account.

SQL Server Service's Log On As account