What is a blown out background?

Question: I've started using Photoshop recently and a lot of people mention "blown out backgrounds", and how to stop them — but never explain what they are. Could someone explain?
Comment: Could you provide a bit more about what the conversations regarding blown out backgrounds are discussing? Recovering detail in areas with blown highlights in the jpeg preview image attached to a raw file? Increasing brightness of darker areas without also pushing the highlights past full saturation (blown highlights)? Something else?
Comment: Hey OP (Teo) what's the context around the question: what are you starting with and what are you hoping to achieve?
Answer: "Blown out" means the maximum value for all color channels.
For RGB, that means maximum red, maximum blue, and maximum green. This appears to be pure white, even if the color of the subject is not white or a shade of gray.
If you take a baby blue wall and expose it properly, in the resulting image the wall will be baby blue. If you over expose it enough, though, even the green and red channels will reach full saturation and it will look white in the resulting image.
This is because there is only so much red that the red channel can record as a numerical value, so much green that the green channel can record as a numerical value, and so much blue that the blue channel can record as a numerical value.
Imagine the image is grossly overexposed and there's enough green light to give a value of, say, 10,000, but only enough blue and red light to give them comparative values of 320 and 442, respectively. If the maximum value for each color channel is 255 (8-bit raster image format), then all three color channels will have a value of 255 (255,255,255) because that is the highest number each channel can record in 8-bits. Since all three channels are at their maximum values, and all three channels are at the same value, the resulting color when viewed will be pure white.
Now apply this to a photo of an interior room with windows during daylight hours. The room is a lot darker than the outdoors seen through the windows. If we expose properly for the room, the widows will show up as pure white squares and no details of the world outside will be recorded in our photo. On the other hand, if we expose properly for the world outside the windows, the interior room will be almost pure black (0,0,0) with details lost in the noise floor of our camera's sensor.
For examples of how this can work out in different types of photography, please see:
Why is it that when the green channel clips, it turns into blue?
Why is my long exposure shot all white?
How to photograph a room showing both room & view out a window?
How many lumens are required to achieve a pure white background in a 40cmx40cm softbox?
Comment: I would think that maxing out *any* color channel should be considered "blown out", especially if two are maxed out.  If a badly exposed object has colors between reddish-orange and greenish-yellow, for example, all of those colors may appear indistinguishably as #$FFFF00.
Comment: @Hueco It could also mean how to recover highlights blown in the original jpeg preview image attached to a raw file. To me the question primarily demonstrates a need to understand the basic meaning of "blown out". Your edit of the question may reflect the OP's intent, but it also may be at odds with the OP's intent.
Comment: This is basically good but since the question is general I don't think it should lead with RGB — the concept (and term!) predates digital and the idea of "color channels".
Comment: Upvoted but OP specifically mentions Post Pro, so context probably around lightening images without causing clipping.
Comment: @supercat We do sometimes use the term in that way, but if all three channels aren't at maximum, we still have *some* information (i.e. there wasn't as much blue here as there was red and green), even if we don't have subject details.
Comment: @MichaelC: If a picture contains a bunch of pixels whose value is are in the range e.g. $FFFF00 to $FFFF04, one might guess that the luminance values of the latter should be much greater than the former, but a huge range of colors would be completely indistinguishable.
Comment: @MichaelC: See for example https://photo.stackexchange.com/questions/61386/why-does-bright-red-in-direct-sun-come-out-orange/61401#61401 for an example of a situation where a partial blow-out is disastrous.  One might try to guess that the orange areas should be red, but if there actually were orange details there, they'd be lost.
Comment: @supercat Agreed, but there is still *some* information available in such a case.  Details are not the only form of information in a photograph. In the case of all three channels at full saturation, there is *absolutely zero information* left. If you insist that all information in a photograph must be *absolutely perfect*, then no photograph is "correct."
Comment: @mattdm What model other than RGB would you propose to use to simply explain how channels in color reproduction systems have a maximum recordable value beyond which no additional information is added? Even with film (or glass plates, or tin-types, for that matter), maximum saturation occurred when all light sensitive chemicals in an emulsion had fully reacted to light and any additional light falling on the film could not induce additional chemical response.
Answer: As a product photographer, you tend to actually want blown-out backgrounds and put up extra flashes in order to get them.
A blown-out background is a background that is so bright compared to the subject that the camera renders it as a uniform contourless white area.
The advantage to such a uniformly blown-out background is that it is rather simple to mark and remove such backgrounds (replacing them with transparency) in photo editors and put something else in.  However, you usually don't want to overdo blowing out a background before fuzzy boundaries like hairs, and the cutouts tend to work mainly before a different bright background.
It would be my guess that replacing such a photographically blown-out background with transparency and possibly afterwards with a different background was what you were reading about.
Comment: Not necessarily. The OP could be reading about processing portraits where the subject is in shade and the background is in bright sunlight. Or about doing real estate/architectural photography where the interiors are much dimmer than the background seen through windows to the brighter outdoors, etc.
Comment: Doing product photography on the cheap, you can sometimes backlight your background as well (paper, for example)
Answer: This word originates in the age of so called wet process when film, or desk, was exposed in a camera and then developed in a dark room. After development the film is no more sensitive to the light and it was projected on a photo-paper which was developed using same process and you got the photograph. The most common was, and still is, a negative process where the lit parts get dark while the unlit are bright.
The blown out areas are such areas of the scene where the film was overexposed so it turns black and no detail could be retrieved from this area. After development of the photo, the area was plain white with the edges blurred so it looks like it was burned.
In digital era and much more powerful postprocessing this term means the same thing: plain white area in the image.
It can be caused by (assuming it is not intended at all):

Wrong aperture/shutter setting so the chip cannot register more light. The capacity of the pixel is saturated. Solution: Adjust Aperture/shutter speed.
Wrong "ISO setting". The amplification setting of the analog-to-digital converter results in values overflowing the highest acceptable value. Solution: Adjust ISO value.
Wrong flash setup. The flash illuminating the scene was not taken in account and triggers one or both causes above. Solution: Adjust the flash setting and/or adjust apperture/shutter/ISO settings.
Wrong postprocessing. The filters applied (brightness, contrast, curves, stacking, HDR,...) results in areas where the maximum values are oveflown. Solution: Adjust the filter properties.

The first two bullets must be anticipated when shooting, no matter what camera you are using - the data is lost before storing anywhere - and the scene must be re-shot. The last point is reversible, but it is a good practice to have unprocessed backups. There is also option of using NG filters or polariser.
Blown out background is just subsidiary of the above because it is specific to the backgrounds.
Also note that if you want [the background] to be blown out the best results come with playing with aperture/shutter/flash and using lowest ISO to get the intended effect. This way one can use the whole bit-depth to hold the nuances in shadows.
Answer: Blown out essentially means overexposed in photography.  It's too bright, and the details for the image highlights are lost.  The histogram for the image is chopped, or leaning heavily to the right.  There are times when this is done intentionally, for a "high key" effect or to make the background super bright/white to contrast with the image subject.  And there are times it is done by mistake, just by exposing the photo incorrectly. So whether it's a good thing or a bad thing depends on what look you're going for.

What is a blown out background?


Ethereum & ERC20 Tokens Integration in exchange

Question: I'm a part on an exchange development and we want to integrate Ethereum, Ethereum Classic and all ERC20 tokens in that exchange. Which wallet will be compatible for these requirements, Is there any official library for the integration of Ethereum, Ethereum Classic and all ERC20 tokens?
Comment: I am looking to ask the same question.
Answer: Most centralized exchanges run an architecture with a few centralized wallets on which they have the private keys. Then on top of this they add a layer of internal accounting to track the balances of all their users. This way when two users of the exchange want to trade, say, ETH vs ERC20, then actually no blockchain transactions occur but the exchange simply updates the users balances to reflect the trade.
This approach saves a lot in term of transaction costs and time to execute transactions. However its centralized nature means users have to trust the exchange...hence decentralized exchanges were invented.
For your use case, you can indeed use any of the major Ethereum clients (Parity, Geth...). As a personal note I would not be very happy to store my tokens on a exchange if I see that one of their developers asked such a question. Trust is paramount, so be sure to know your full technical stack completely before you start taking in users funds. An exchange is no small technical feat!
Answer: you can use web3.js or Nethereum   (a c# lib available at : www.nethereum.com) for Ethereum & Erc20 tokens implementation, however to run full node, you can use geth.
https://geth.ethereum.org/downloads/


I have a crate of out of date beer/bitter by 6 months, tastes watery, can I resurrect it in some way?

Question: I found a case of Scottish beer / bitter that I had forgotten about, it is out of date by 7 months, which normally would not stop me but it tastes watery. My question is can I re-ferment it or add something to resurrect it?
Comment: Do you mean that it doesn't have any carbonation? Could you list the beer so I/the community knows more of what the beer should taste like?
Comment: *unable to comment*, but refermenting is dependent on whether the beer is a [real ale](https://en.wikipedia.org/wiki/Cask_ale), which means that yeast is still active in the beer. If you know anything about the style or age, that would be useful information, but most likely, you can make a beer cocktail, (use google for recipes for certain styles) or something like a michelada out of it.
Answer: I seriously doubt it. What happens over time is that chemicals giving the taste decays, and you cannot magically make them appear. You could perhaps add something to give it taste, but then, is it still beer?
Refermenting (could be done by adding sugar) will give carbon dioxide and alcohol, but not more taste.
Answer: Could pour it into something like this and infuse it with more hops or adjuncts.
Comment: Hi newGuy, can you please expand your answer to include more detail?  If the link becomes invalid, there will be no context to understand what you're suggesting.
Answer: If it's not a beer with a high alcohol percentage (say 7%+) I'd just throw it out, life's too short to drink stale beer.
Otherwise you can test several bottles. You might get lucky with a few, not every bottle in the same case ages at the same rate, certainly if it's one with fermentation on the bottle.
tip: If you hear a hiss when opening the bottle, it's safe to taste. I never trust a bottle that's silent when opening as it almost guarantees that it's gone bad.


How can I boost my Solo MMR in Dota 2?

Question: I've been playing Dota 2 for a while now. I started my account with 700 MMR on solo and managed to reach 2.7k in the first 3 months. Nevertheless, a year has passed since then and I'm stuck on 2.7k. My party's MMR is 3.7k. Are there any tips on improving the solo MMR score?
Answer: There is only one way to gain MMR: through winning, as you might have thought. There currently is no other way (other than paying for a boost which is frowned upon) to do this, but there are some ways to give you a better chance at winning, therefore increasing your MMR indirectly.

Use meta Heros - dota 2 is a game where things are constantly balanced and changed so everything fits together. But things don't always go as planed, since Mr Icefrog can't crowd test every change and some Heros end up more powerful than others. As shown by this question, you can see blood seeker was an extremely OP hero in 6.86c, and recently in 6.85 Doom was the best due to the buff to his Scorched Earth ability. The best way to see what's good at the time is by going to the hero trends page on DotaBuff and sorting by current win rate.
Play as a team, don't put anyone down - Dota 2 is a team game, which means teamwork is key. I see too many times people lose just because they flame a teammate that didn't have a good game, or can't handle an aggressive tri-lane. If someone is feeding but you don't think it's on purpose, suggest them to farm the jungle instead of trying to farm lane, and make sure wards are up (more below) so they can see that they could be ganked.
Vision - Most people, especially in the lower brackets, will underestimate the role of the supports in a game. Supporting is probably one of the most crucial parts of Dota, even beyond the role of the carry. Supports make sure the team knows when to  fall back because of spotting the enemy with a ward or when to engage into the rosh pit by surprise and wipe the enemy.
Communication - this is key. Some people are so focused on their lane they might not notice the enemy mid walking to them with a rune ward, so when you spot it call it out, either ping the enemy hero portrait and ping their lane or use the mic.

There are more ways, but these are some of the best options. Using these is likely to increase your chances of winning, therefore increasing your MMR overall
Comment: i shifted from carry to support because in low mmr games people generally rush for carries.
Comment: @RishabhSharma I have noticed that that usually works below 3k, and a current meta hero is vengeful spirit.
Comment: 2.7K mmr is the biggest wall in front of you. I went down to 2.4 4-5 times and come all the way to 2.7 by winning continuesly but there will be down fall again onece you touch 2.7k. i dont know why because I know why I lose games, but I don't know why I can't cross 2.7k no matter what role, you chose to play. there must be some thing to do with valve mmr system. I can atleast suggest, don't random and don't try heros which you don't know much.  forget about the versatility and pick the heros who u can play better that including support heros and junglers
Comment: @Judge2020 yes great advice. I have seen vengeful get picked most of the games these days.
Answer: Judge2020's answer is good, but one huge difference you'll notice if you see any pro games is how good they are at farming. Last-hitting is a HUGE part of the game. You'll often see 50-60 plus last hits for the carries/mid lane at the 10 minute mark and this makes a huge difference - 50 last hits gets you somewhere around 2-2.3k gold depending on how many siege creeps you get etc.
Practice your last-hitting, using the ingame last-hit practice if necessary. Get good at it and get the timings down for like 5-10 heroes and you'll see a big uptick in your effectiveness. If you're playing support this still applies but you should ideally be denying in lane to stop the enemy's farm.
Comment: i aggree that last hits are important for carries and mid lane but what if they are not good enough? or else what if they take last hits and then die to a hero :(

How can I boost my Solo MMR in Dota 2?


Checking earned companion perks?

Question: Is there anywhere in game to check your earned companion perks? I don't see companion perks listed on the Perks Chart, was wondering if there was anywhere else they might be listed?
Answer: I figured out how to find the companion perks earned, can't believe I missed it.
On your Pip-Boy (Press B on XBOX 1)
On the STAT tab
Switch subtab to PERKS (Twice Right on the D-pad)
This menu subtab lists all the perks you've purchased with XP plus the perks earned through companions and perks found including issues of Grognak, Astoundingly Awesome Tales, Live & Love, Wasteland Survival Guide, and others as well as US Covert Ops Manuals.
Answer: Perks are only listed if they are active. You would either have to keep track yourself of which ones you've unlocked. Or if you aren't sure and haven't kept track if you have a particular followers perk, you can have them follow you then check your active perks.
Comment: [Companion Perks are permanent, whether they are follow you or not](http://fallout.wikia.com/wiki/Fallout_4_perks#Companion_perks). 'Lover's Embrace' is counted as a 'Temporary Perk' because it *does* require a loving companion to be nearby
Comment: @Robotnik Lover's Embrace is also a temporary perk because it only lasts a certain amount of time after taking a rest with your "lover" nearby.
Comment: @Robotnik "Lover's Embrace" requires a romantically-involved _character_ to be nearby _when you rest_. There are two important distinctions here - 1.) They don't have to be a companion; there's a lounge singer you can flirt with and take her to bed. 2.) They have to be there when you rest, you don't have to keep them with you. I keep my romanced Cait at Sanctunary, but I use other companions in the field.

Checking earned companion perks?


What law forces cookie dialogs on websites?

Question: The Web is now covered with poorly designed, intrusive and ineffective dialogs warning about cookies.
Presumably this is as a result of an EU directive. Which UK law enacts this directive?
Comment: @DVK We had these "this site uses cookies" warning before the GDPR. The GDPR just extended it.
Comment: This appears to be a question about laws themselves, not about the politics and political processes which create them. This makes this question more appropriate for Law Stack Exchange than Politics Stack Exchange.
Comment: https://www.itgovernance.eu/blog/en/how-the-gdpr-affects-cookie-policies
Answer: As SJuan76 mentions in a comment, the first cookie-related EU law was:

Directive 2009/136/EC of the European Parliament and of the Council of 25 November 2009 amending Directive 2002/22/EC on universal service and users' rights relating to electronic communications networks and services, Directive 2002/58/EC concerning the processing of personal data and the protection of privacy in the electronic communications sector and Regulation (EC) No 2006/2004 on cooperation between national authorities responsible for the enforcement of consumer protection laws

This being an EU Directive, it required transcription into UK law to be valid in the UK. This was effected by:

The Privacy and Electronic Communications (EC Directive) (Amendment) Regulations 2011

This is a statutory instrument made under the European Communities Act 1972, and came into force on 26 May 2011.
Answer: It is not a directive, it is a regulation
More specifically, it is the General Data Protection Regulation, or GDPR; we even have a tag for it.
Now to the core of the question, GDPR being a regulation and not a directive means that it enters into effect without need of national Parliaments to adapt their laws to enact it. Or, as the GDPR FAQ page explains

What is the difference between a regulation and a directive?
A regulation is a binding legislative act. It must be applied in its entirety across the EU, while a directive is a legislative act that sets out a goal that all EU countries must achieve. However, it is up to the individual countries to decide how. It is important to note that the GDPR is a regulation, in contrast the the previous legislation, which is a directive.

In any case, some aspects of the GDPR1 are left to the national Parliaments to decide. In the UK there is the Data Protection Act of 2018

1For example definition of what is the age limit for "minors" or if permission is enough to process highly sensitive data like health data.
Comment: AFAIK it would be the [2009/136/CE directive](https://eur-lex.europa.eu/legal-content/EN/TXT/?uri=celex%3A32009L0136), which ammended directives 2002/22/EC, 2002/58/EC and regulation No 2006/2004. It seems that one issue is that it asked for "consent" but it not required it to be "explicit" (i.e. it could be argued that as long as there was a way of rejecting the cookies and the user did not use it there was consent), This is one of the reasons why the GDPR (that in no uncertain terms requires explicit consent) has led to all those dialogs.
Comment: Thank you. The "cookie law" was in effect well before GDPR. Does this mean GDPR incorporated, superseded or extended it?
Comment: GDPR incorporates many provisions that affect cookies, as those can be used to gather personal data (e.g. if a cookie tracks which pages you visit in order to sell publicity then GDPR stipulates that consent is needed), but does not focus on them. It does not supersede or extend the cookie law (i.e. it is not derived from it) but it forces additional constraints.
Comment: Thank you. Do you know what regulation or directive imposed the original cookie law?
Answer: SJuan76's comment from a different angle:

GDPR incorporates many provisions that affect cookies, as those can be
  used to gather personal data (e.g. if a cookie tracks which pages you
  visit in order to sell publicity then GDPR stipulates that consent is
  needed), but does not focus on them. It does not supersede or extend
  the cookie law (i.e. it is not derived from it) but it forces
  additional constraints. – SJuan76 3 hours ago

Basically, the Cookie Directive and GDPR operate on 2 different levels, which might overlap: we can say that GDPR applies only as long as the cookie is collecting data considered "personal" or "online identifiers" by the Regulation. If it happens, then the consent window (you called it "dialogs warning") has to be more strict, as per GDPR requirement (I am just mentioning one of the effects). Otherwise, the less-strict Directive will apply.


Flight Level Change or Vertical Speed - When to use it?

Question: I've heard that some pilots have this difficulty to determine the correct use of both features. So, which is the difference between using the vertical speed, instead using the flight level change during a descent? When, and how to use it?
Answer: FLC mode maintains airspeed during a climb or descent, while VS mode maintains a specific vertical speed.
Often air traffic controllers will request that you "maintain 250 knots in the descent" or something to that effect, which is much easier to achieve when using Flight Level Change. As another answer points out, by maintaining airspeed, climbs are made safer as the autopilot will not attempt to maintain a rate of climb regardless of whether or not the airspeed is safe.
FLC mode is typically only available in advanced autopilots, and as far as I know they need to connect to an Air Data Computer to get the necessary information.
How to use FLC would depend on the equipment available to you:

aircraft with auto throttle will maintain speed and an appropriate rate of descent automatically.
for aircraft without auto throttle you'd set your target altitude, enable FLC, adjust your target speed if needed, and set your throttle for climb or descent to maintain the desired altitude change rate.

I'm referencing the Garmin GFC700 as it's the only autopilot I've used with FLC mode, but I imagine the same steps and rules would apply.
Answer: Just MHO:
Vertical speed should never be used when climbing because you could stall if insufficient power is added for the requested climb rate. Using FLC when climbing guarantees you maintain the best airspeed (best rate or best angle, depending on the situation)
On the other hand, when descending I always use VS mode because it gets you down to the proper altitude in time (if you've calculated the required VS before starting your descent). It also prevents physical discomfort for you and your passengers. If you use FLC during the descent you have to be very careful with power in order not to exceed safe airspeeds (in addition to the discomfort caused by excessive descent rates)
Not an expert opinion but just a personal opinion...
Comment: We used vertical speed hold in the climb routinely in the EMB-145 because airspeed hold would porpoise worse than a student pilot while it chased the speed bug.  As long as you are doing your job and monitoring the airplane, you are in no danger of stalling (and add to that we climbed at 290 kts transitioning to M.65 or M.60 so we had a decent stall margin).
Comment: V/S "never" used while climbing???  If I'm climbing to FL300 and traffic ahead is descending to FL310, I absolutely would use V/S in order to shallow out the climb and avoid a TCAS RA!  USUALLY level change (or VNAV -- accomplishing the same thing) is the best option for climbing, but not always.
Comment: This is a good point and one I failed to mention in my response. Because FLC is essentially airspeed-hold mode, there's a much bigger margin of error. :)
Comment: @RalphJ Note that I ended my answer with "just a personal opinion"
Comment: @RalphJ you can still shallow out the climb while in FLC mode though. In some autopilots it's even done using the very same up/down buttons that you would use when you are in VS mode (e.g. GFC 700).
Answer: They are different modes that control aircraft pitch in different ways, and as a pilot you select what you want based on your current requirements.  Note that the modes even behave differently depending on the aircraft / autopilot, so referring to the actual aircraft/autopilot documentation is essential.
Many autopilots don't even have a Flight Level Change mode, but instead have an Indicated Airspeed (IAS) mode.
Autopilot modes like these are typically "dumb" and just do what they are told, without taking anything else into consideration.
Regardless of which mode that is used, remember that it is the pilot responsibility to monitor the aircraft and to make sure that it is doing what they want it to do!
Indicated Airspeed / Flight Level Change

This mode usually adjusts the pitch of the aircraft in order to maintain a specific airspeed.  In simple systems, the only inputs that are used are airspeed and aircraft pitch.
You usually control the vertical speed of the aircraft by making power adjustments:

By reducing power, your vertical speed will decrease.
By increasing power, your vertical speed will increase.

In some systems your actual altitude is compared to the selected target altitude and a minimum climb or descent is maintained even if the airspeed can't be maintained.
In some systems the aircraft altitude is used to change the behavior (for instance, in one aircraft that I have flown, if you are below 8,000 ft MSL and hit FLC, it will descend at 1,000 FPM but if you are above 8,000 feet it specifies a 250 KT IAS hold).
In some systems, the pitch is adjusted to maintain a specific climb/descent schedule which automatically changes based on altitude.  For instance, a descent schedule might be Mach 0.80 until 29,000 ft., 350 KIAS until 10,000 ft. and 250 KIAS below 10,000 ft.
Another aircraft that I have flown in the past even had two climb schedules. You could toggle between the "normal" climb and the "high speed" climb by hitting the FLC button more than once.
A lot of autopilots (especially older ones) tend to oscillate around the target airspeed and constantly pitch up and down while trying to fly a specific airspeed.  For this reason (keeping in mind that passenger comfort could be an issue) many people avoid speed modes, especially at higher altitudes.

Vertical Speed

This mode usually adjusts the pitch of the aircraft in order to maintain a specific vertical speed.  Again, it is usually a "dumb" mode and doesn't look at anything but vertical speed and aircraft pitch.
Comment: Flight level change in the advanced systems like Airbus  is coupled to autothrust and selects Climb (CLB) or Idle thrust as appropriate.
Comment: @JanHudec While true, autothrust is an independent system which just responds to other factors based on the mode that **it** is set to and whether or not they are even engaged.
Comment: @Lnafziger: I am pretty sure in Airbus if A/T is engaged and A/P is in "open descent" (flight level change to lower), idle thrust is selected (and A/P maintains the selected speed with pitch). It's described in [this incident report](http://avherald.com/h?article=455c3eae/0000).
Comment: @JanHudec I have no doubt that it works that way, but like you said, if **auto throttles** are engaged.  It's a different system than what the question is about so I didn't discuss it here.  :)
Comment: @Lnafziger: Yes, A/T has to be engaged. The reason for that incident was that pilot selected idle manually, which did not change the rate of descent, but disengaged A/T, so the thrust was not automatically increased again when they reached the assigned altitude.
Answer: In "full up" FMC/VNAV/Autothrottle airplanes, Level Change tends to be an "all or nothing" option for power: full climb power to go up, and flight idle to come down (with pitch holding the commanded speed in both cases).  With Vertical Speed, the pitch holds your climb rate constant, and the throttles vary to hold your airspeed.  With a sufficiently large V/S value commanded, you reach either full climb thrust or flight idle, and then the throttle can't affect airspeed any more -- so you can lose airspeed with a steep climb commanded, or gain it with a steep descent.
And then at some point, you look up & wonder why we're so fast/slow, and realize that V/S has done you in, and you go back to flying the airplane.  :)
One reason that I personally prefer V/S over level change in certain circumstances is that the latter tends to be fairly aggressive about maintaining speed, so in gusty conditions the autopilot (in level change) will end up pushing & pulling quite a bit to hold the speed +/- a knot or two.  I think that tends to be an uncomfortable ride, so I'll go to V/S and let the speed fluctuate (the autothrottles can chase it, or I deselect them & just leave a stable power setting) while the pitch attitude stays constant.
At some point, you go back to a speed mode (i.e. once you level off), but for the stable pitch instead of constant push/pull/push/pull, V/S has its advantages.  Just don't ignore it long enough to let your speed do undesirable things to you!


Why don't block ciphers consist of a simple XOR operation with key like Stream ciphers?

Question: If the construction of stream ciphers is already secure why does the construction of block cipher involve pseudo permutations and complex operations that makes block ciphers less faster?
Is a construction of a block cipher defined as just Xor-ing a block of bytes with a block of key bytes (removing all permutations and other operations) not secure?
Comment: The general term 'block cipher' and the technical cryptology term 'pseudorandom permutation' are _almost_ synonymous.  (The difference is that some cryptology literature assumes a somewhat stronger technical condition, 'ideal block cipher', like 'random oracle' for a hash function.)  You might find better enlightenment by asking: What _is_ a block cipher?  What _is_ a stream cipher?  The answers to these may make the answer to your question obvious in retrospect.
Answer:
If the construction of stream ciphers is already secure why does the construction of block cipher involve pseudo permutations and complex operations that makes block ciphers less faster?

Because stream and block ciphers are not in fact comparable types of object.  They're practical approximations to two different types of ideal object:

A stream cipher is designed to behave like a randomly-chosen one-time pad.
A block cipher is designed to behave like a randomly chosen permutation of the set of all bit strings of a fixed length.

Note also that:

For a message of length $n$, there are $2^n$ distinct pads that could be used to encrypt it.
For a block size of $n$ there are $2^n$ distinct values, and therefore $2^n!$ (the factorial of $2^n$) distinct permutations of blocks of that size.

$2^n!$ is a vastly larger number than $2^n$.  It follows that the probability that a randomly selected $n$-bit permutation will have the same effect on its inputs as the application of any of the $2^n$ one-time pads of length $n$ is therefore very unlikely.  And this means you can't build a reasonable block cipher by using the OTP strategy of XORing to the input; XORing with an OTP only allows you to permute inputs in $2^n$ different ways.

One piece of practical advice: in spite of many introductory cryptography materials' description of block ciphers as "encrypting messages one block at a time," try not to think of block ciphers as message encryption algorithms at all.  Think of them more as a basic building block that tries to behave in a very specific, well-defined manner, which cryptographers then reuse to build practical encryption algorithms out of.
Comment: Can't emphasize enough how harmful it has been for textbook authors to promulgate the deceptive simplicity of the concept of a block cipher encrypting a message a block at a time.  Always calling it a pseudorandom permutation family might help to dissuade unwary laymen from handling such sharp-edged tools…
Comment: But isn't a block cipher with a fixed key is also a 2^n permutation?
In this case what makes us use PRPs with fixed key in cryptographic constructions instead of simple XOR?
Answer:
If the construction of stream ciphers is already secure why does the construction of block cipher involve pseudo permutations and complex operations that makes block ciphers less faster?

A stream cipher consists of more than just a single XOR operation. They first have to spend time generating the key stream from the key and nonce/seed. They actually use many of the same operations and take about the same amount of time as a block cipher does to do so.
For example, Salsa20 is a stream cipher that uses addition, rotation, and XOR to generate the key stream.

After the key stream is generated, it is combined with the message via XOR.
The stream cipher is only secure if the key stream is unpredictable. The complexity and time goes into making the output unpredictable.

Is a construction of a block cipher defined as just Xor-ing a block of bytes with a block of key bytes (removing all permutations and other operations) not secure?

Yes, such a construction is insecure. Suppose that the adversary knows a single plaintext message. They can simply subtract out the known message to retrieve the key, which allows them to subtract out the key from any other ciphertext to recover the plaintext message.
$c \leftarrow m \oplus key\\
key \leftarrow c \oplus m$
Unless your messages are the output of a random number generator and have 8-bits per byte of entropy, then they are susceptible to a known plaintext attack. Any meaningful message will not have 8-bits/byte of entropy, and so you have to assume that the adversary already knows the plaintext messages when designing a cipher.
Additionally, assume that you have two messages $m_1$ and $m_2$ that differ by only a single bit. When you XOR the key into them, the only difference in the resultant ciphertexts is at the place where the messages differed by one bit. A block cipher should produce a random permutation of message blocks, and this is clearly non-random behavior. A block cipher needs to spend time creating diffusion, where flipping a single input bit flips approximately half of the output bits.
Answer: An XOR cipher is insecure if the same key is used more than once (or, more generally, if any bit of the key is used to encrypt more than one bit of data).
For stream ciphers, this is fine, since the keystream can be made arbitrarily long.  (Of course, the keystream generator itself must involve something more than just XOR.)  But in a block cipher, we want to be able to encrypt many blocks with the same (relatively short) key.  If the encryption process consisted of just XORing the key with the block, this would become insecure as soon as we tried to encrypt more than one block with the same key.
Of course, we could consider having some kind of a key expansion process that generated an endless stream of "block keys" from a single master key, and then just XORing each block of data with a different block key.  But this would really just be a stream cipher operating on blocks of data, not a block cipher.
Comment: But even for a block cipher many-time key encryption is not possible unless there is a mode of operation that involves block chaining with nonce or random IV, and I assume such modes won't work if the block cipher is just a simple XOR, is that correct?


Login using Facebook Authentication - FBApp Installed

Question: I am following the Scrumptious sample that is on the FB Developers site (https://developers.facebook.com/docs/tutorials/androidsdk/3.0/scrumptious/authenticate/) I successfully implemented everything up to the end of step 2 without any errors.
But i noticed that if i have the Android FB Application installed on my device then it does not log in.
It asks permission to access my public profile and friend list (to which i reply OK). After that it execute onSessionStateChange() but state = CLOSED_LOGIN_FAILED.
I did verify that:

My app is listed on https://developers.facebook.com/apps
I checked and my Native Android App option is ticked
i also have my Package Name, Hash Key entered.
The Facebook Login option is also enabled.

Please can someone help me to get this working :-( i am
struggling with this for 2 days already and no luck.
Thanks.
Comment: Problem has been resolved. After i generated the HashKey using the KeyTool.exe and entered the password as android it gave me a different key. I copied this to the dashBoard on Facebook and it worked. Sorry for wasting your time
Answer: Problem has been resolved. After i generated the HashKey using the KeyTool.exe and entered the password as android it gave me a different key. I copied this to the dashBoard on Facebook and it worked. Sorry for wasting your time


How to select cameras for a stereo vision system?

Question: I am in the process of building a stereo vision system to be used on a UGV. The system is for a robot that will be used in a competition wherein the robot is teleoperated to find relatively small colored rocks in a large outdoor field. I understand how to calibrate such a system and process the data for a stereo vision system. I do not however know how to select cameras for such a system. What are the best practices for picking cameras for a stereo vision system?
Answer: Off the top of my head I would go by the following selection criteria

color/b&w - usually b&w is better, since the stereo algorithms only use one channel anyway
baseline - this really depends on the scene. With the baseline you control how much accuracy you get with distance. Wider baseline results in higher disparity values and thus less noise on the distance estimation. Higher baseline also means that you will get a reduced overlap between your field of views. Most importantly though, the wider the baseline the harder the matching between the two views. So the quality of the result goes down.
shutter - always use a global shutter for anything with computer vision on mobile robots
resolution - most stereo algorithms are computationally expensive. And you will likely not need that many 3d points. In the near field the sampling density is usually enough, and the far field your error from the low disparity is more of a problem than sampling density. 640x480 is fine in most cases. Some chips have a wider aspect ratio, which is favourable for the overlap, but you can get the same with using a sub-window of your chip.
lens/field of view - for mobile outdoor robots I prefer a wide field of view over narrow field of view. More or less for the same reasons as the resolution. Make sure your lenses are rigid and have a means to fixate any moving parts e.g. like adjustable focal length. In most cases a fixed focal length is fine anyway, since you are limited by the selection of your baseline.
trigger - when you create your own stereo rig, your cameras should support hardware trigger and ideally one should trigger the other.
framerate - In my opinion the least important consideration. Unless you have a lot of processing power you won't be getting much more than something like 5 Hz anyway. So your algorithm is much more likely to be the bottleneck, rather than the chip or the connection.
interface - Most cameras come with Firewire/USB2/USB3/Ethernet. USB2 is useless as it consumes a lot of CPU. Firewire is good if you have a port, but I think it seems to be on the decline in favour of USB3 these days. Didn't have much experience with USB3 yet. Ethernet is quite nice because you are more likely to find embedded systems with GigEthernet than USB3 at the moment.
housing - as rigid as possible. Recalibrating is an annoying procedure.
Answer: A few things you should be on the lookout for:

Global shutter basically means all pixels get captured at the same time, as opposed to Rolling shutter where they are captured sequentially in a line scan fashion. Since your UGV will be moving around and performing stereo algorithms over the images you capture, it could be important that you avoid aberrations that occure when camera move, such as the ones seen in the pictures below (taken from Wikipedia):

Camera synchronization in hardware is achievable by some cameras, notably firewire cameras AFAIK. That can greatly improve the results for stereo when things are moving around.
Mounting should be done in a way that changes in the extrinsic parameters (the relative pose between cameras) for the stereo pair will be unlikely to change after calibration. In your rig that might be more important, since the UGV might face uneven terrain outdoors and things will vibrate.
Dedicated stereo hardware makes it possible to acquire disparity images directly as output of your stereo vision system, which eases the load off your embedded computing. It also tends to be much faster than running the very same algorithms in software.

As usual, the more you're willing to pay the better the results. To be honest, if you're able to buy a full-blown stereo camera such as the Bumblebee2, that's what I'd do. Otherwise, if you're on the cheaper side, I would simply go with a Kinect: it's unlikely you'll be able to get a system that outperforms it for the same price.
Comment: The question was for an outdoor system. This effectively rules out the Kinect. Also, the algorithms that come with the Bumblebee are far from optimal, we found.
Comment: I'm with you on the Kinect comment, but can't the stereo algorithms that come with the Bumblebee be substituted with your own code? The biggest advantage I was pointing out was in the actual hardware, not the software that is bundled with it.
Comment: yes that is true. You can use it just like two normal cameras, and it has the advantage of a rigid housing.
Comment: not only that but global shutter, good lenses and other goodies
Answer: You should start by calculating how many frames per second you need, and how much camera resolution you can process at that framerate.  If nothing else, that will prevent you from overspending or from buying a camera that won't suit your needs.
Beyond that, there are a variety of features that make the choice more difficult/interesting.  Different cameras (especially network cameras like Axis) allow you to alter the image quality, or to specify a max bitrate for the image stream.  Some cameras also give you choices on the shutter speed, allowing you to favor a constant exposure time or a constant average illumination in the image.  Some cameras are more sensitive than others (the last time I worked with this was in 2009, and we noticed that the PS3 Eye did really well in low light conditions).
Probably the best thing you can do would be to run your image processing algorithms on a few static images that you take with a DSLR, then attempt to reduce the frame size and quality to see where things begin to break down.
Answer: That is an interesting topic, and not very easy to get right on the first try. From experience with this, here are the most important things.

Synchronization. The camera must be 100% synced. For example, say the UGV is driving at a modest 36Km/hr (10m/s)  and recording frames at 30 frames per second. That is, at every frame the UGV would cover 3m. Now, say your sync is off by 1ms, one of the cameras will be off by ~0.3m, which is bad [just off the top of my head]. Sync problems are very hard to detect.
Resolution. In the context of stereo, we refer to depth resolution, or how much depth can we resolve given a change in disparity. An excellent explanation can be found here http://pub1.willowgarage.com/~konolige/svs/disparity.htm The equation you want to look at is a function of the focal length of the image and the stereo baseline. $\delta Z = \frac{Z^2}{Bf}\delta d$. This says that depth resolving power $\delta Z$ is inversely proportional to the baseline $B$ times the focal length $f$. That is the longer the baseline, the smaller $\delta Z$, the better. Meaning, you can resolve more depth. The minimum change in disparity $\delta d$ is controlled partially by the image resolution and the algorithm used. For your calculations, you can safely assume that $\delta d$ is at least $1/2$. It is better to be conservative with the choice of $\delta d$.
Overlap. You want to have overlap between the cameras to get stereo. Hence, you need to choose a combination of lens focal length (field of view) and baseline so that you have enough overlap for the application. Basically, trigonometry work on the board, or a quick matlab/python script.

For UGV's, there are two uses for stereo.

Navigation and Pose Estimation In this case you most probably need a large baseline + long focal length. This allows the stereo to see and resolve depth better and longer range.
Obstacle detection and avoidance You will probably need a shorter baseline and wider lens (smaller focal length) so that  you can focus on things very close to you.

Some UGV's might have both stereo setups, the large baseline narrow field of view for navigation and another one or two for obstacle avoidance.
Be very careful what you buy. Some companies offer already built stereo setups. Those are great on the robustness side of things, they don't loose calibration easily and are always in sync. The problem is that the commercially available ones have a small baseline. If you want to build your own. I'm guessing you will end up doing so, make sure the camera are syncable. Firewire is great for this, two camera on the same bus will sync with 125microsecond accuracy out of the box! USB and Gige cams are painful to sync.  When you put everything together, you want to make sure that the lenses are not going to move at all, and the baseline is rigid, very rigid for the application.
Also be careful in lens selection. Not all lenses work with all cameras. Lenses have a resolution too. This is a another topic, here is a short article on this http://www.qualitymag.com/articles/90642-q-a--selecting-lenses-for-machine-vision-systems
Comment: Your synchronization computation is wrong. 30 FPS at 10m/s gives a distance of 33cm (not 3m) per frame. Also 1ms at this speed means distance of 1cm (regardless of FPS). So synchronization on ms level is a super result actually for such speeds!


What settings are the most energy efficient on a Nook Color?

Question: I have seen some touch screen readers that have a gray on black background scheme that helps to reduce the power consumption and increase battery life. But those settings do not really exist on the Nook Color that I can find.  What setting is more efficient, and does it save any significant amount of battery life? Is there any way to do a custom color set?
Answer: Generally, the best way to save battery on a NOOK Color (or any device) is to:

Lower the brightness
Turn off Wifi and Bluetooth unless necessary

These two steps can more than double your battery life on some devices.


Marking implied vol surface daily with sticky strike and sticky delta

Question: Suppose that implied vol surfaces are calibrated once per month due to data restrictions (i.e. option data is only available at month end). How can a trading desk remark their vol surfaces on a daily basis by only observing the spot and time to maturity? I have heard of techniques such as sticky delta and sticky strike. How do those techniques work? When would one use one technique over the other?
Answer: These are introduced in the GS Note on Volatility Regimes. Oversimplifying (a good amount) they say that the surface will look the same based on strike or delta.
E.g.: sticky strike- if your spot price is 100 and the 80 put is trading at 20% volatility according to your surface, you will re-calculate the put price at 20% volatility with your new spot price (the vol per strike has not changed, even though the spot price and therefore the option price has). Sticky delta (more robust) would change the computation to include the new moneyness level, so after a 10 pt rally in spot would have reduced from 80% moneyness to 72%, so you would calculate the option price with your calibrated surface's 72% moneyness vol level.
Answer: I am working in a trading desk. We don't construct volatility surfaces daily for small-medium entities, but instead, refreshing them in several days. You may need to use proxy and interpolation to estimate quotes first. Sticky strike and sticky delta are the assumption for risk calculation, such as delta and vega.


Are there any temples for Mohini avatar?

Question: We see many temples of Lord Vishnu, Rama, Krishna, Narasimha. Also temples for Varaha, Kurma, Hayagriva etc.. Are there any temples for Mohini avatar? Also, which avatars don't have temples and why?
Answer: Temples dedicated to Mohini Avatar are very rare. There are two temples where Mohini avatar is presiding deity.

Jaganmohini Keshava Swami temple located at Ryali, Konaseema, Andhra Pradesh.

Mahalasa Narayani temple. Mardol, Goa.

Mahalasa Narayani is identified with Mohini Avatar of Lord Vishnu. She is family deity of many families. Goddess Mhalsa is considered as Mohini as well as Parvati. Even though Mahalsa is identified with Mohini in the shrine, some traditions consider Mhalsa as incarnation of Goddess Parvati.
So, that makes Jaganmohini Keshava Swamy a unique temple for Mohini Avatar.
The idol in the temple is made of a single salagrama stone (Salagrama Ekashila). The deity looks Vishnu from front view and Jaganmohini with long hair when looked from the rear.
The temple history is associated with the Samudra Manthan episode from the Puranas. Following is the sthala Puranam (temple History from East Godavari District website):

According to the legend "Bhagavatam" while Devatas and Rakshas were quarrelling over sharing of holy Devine nectar "Sree Maha Vishnu" came to the rescue of Devatas in the guise of Mohini and convinced both the rivalry groups promising to distribute holy Devine nectar in equal share to Devatas and Rakshas. But in the interest of universal peace and welfare of sages, holy and Devine nectar was distributed among Devatas alone and the Mohini disappeared.
Lord Siva having seen the most fascinating beauty of Mohini allured her. He chased her for getting for a while the presence of his consort Parvathi Devi it is the general belief that the holy incident was the result of birth of "AYYAPPA SWAMY". One flower from the plait of Mohini fell down and it was smelt by Lord Siva. Then he surprisingly found "Sree Maha Vishnu" in the form of Mohini and felt shy for his behavior. The place where the flower from the plait of Mohini fell is named as RYALI the Telugu meaning of "Fall"

Almost every incarnation have temples. Even Parashurama has a few temples dedicated and worshipped. Lord Brahma has only few temples and probably new temples are not constructed due to the curse of sage Bhrigu. According to Shiva Purana, it is Lord Shiva who banished Brahma from temple worship and only gave the presidency over all the Yagnas.
References :
Wikipedia article on Mhalsa
Front Vishnu Back Mohini Ryali Mohini Avatar Temple
Temple History of SRI JAGANMOHINI KESAVA & GOPALA SWAMY TEMPLE, RYALI from East Godavari district official website.
Why are temples devoted to Brahma so rare?
Ryali,
Lord Jaganmohini Keshava Swamy Temple from inkakinada.com
Comment: Good info. Are there temples for Buddha, Kalki etc.? I am asking temples where there are the vigrahas of these avatars worshipped.
Comment: @krr Thanks. Buddha is not worshipped in Hindu temples because he advocated a different religion. His teachings do not match with Vedas. Kalki incarnation is yet to appear. So, there won't be many temples. There are only a few temples here and there based only on prophecies. However, there are sculptures and paintings on temple walls. There might be something in the Agamas about mantras but I am not sure..
Answer: This is just an addition to Sarvabhouma's answer.
Padma Purana, Uttarakhanda, In Chapter 241 Lord Siva relates the story of Parasurama to mother Parvati.

79-81. O goddess, I have told you this account of the incarnation of
  lord (Visnu), holder of the Sarnga bow, who had entered (Parasu)Rama with his
  power. Due to the entrance of the power this (form) of the noble one
  cannot be worshiped. The chief, noble, brahmanas, the devotees of the
  lord, should worship the incarnations of (Dasarathi) Rama and Krsna,
  perfect with virtues, worshiped by sages, and giving salvation to
  human beings.

From this what we can infer is that sakty-avesa avatars need not be worshiped(although there may be some temples). Avatars like Kurma, Rama, Varaha, Hayagriva, etc.. should be worshiped.


importing a good mesh

Question: Im importing and svg file and when i go to edit mode get some 1000's mesh and edges,etc. Is there a file to get a clean mesh. Image is attach object mode look fine but when turn to edit mode 1000's of mesh. Is there any other file format which we can get a clean mesh.

blender file
file disappear
Comment: To use the remesh modifier your mesh must have volume. You need to extrude all your geometry like in @Paul Gonet's example below, then the Remesh modifier will work.
Comment: Mesh looks alright to me honestly, this is a fairly complicated pattern that requires a lot of polygons to represent. Might be simpler using ngons but the importer and simple conversion from curve to mesh is unlikely to generate these.
Comment: To get that much detail you need many vertices. If you want to work with simpler geometry then do not convert your curves to mesh after importing SVGs
Comment: a file attached problem im getting as soon as the remesh added it disappears
Comment: i have tried adding but its not working with my mesh can u plz try with my mesh
Answer: There is no other file format that will guarantee a better mesh topology, unless you import as NURBS, but Blender can not import NURBS nor handle that kind of geometric complexity.
As TLousky mentions the results you are getting are totally normal and expected when converting a bezier curve into a mesh. However I would advise to not convert the SVG curve into a mesh, unless you specifically need to and only when you need to.
Keep it as a Bezier Curve object as long as possible, it's non destructive,  will be easier to edit and maintain while being easily editable as a bezier curve handles.
Also have a look at my answer about cleanup techniques for bezier curve objects, useful both for keeping as curve or before converting to mesh for a cleaner topology.
Have in mind that converting Bezier Objects into meshes will always leave a mesh with uneven topology and lots of triangulated edges. You may later clean them up a bit by turning flat faces into NGons.
That won't improve topology nor benefit unwrapping or editing, but it may give a cleaner viewport.
Comment: a file attached problem im getting as soon as the remesh added it disappears
Comment: and in ur image after u clicking the face what hot key u have press u got that normal and other options
Comment: Press `Shift +G` in edit mode to bring up the *Select Grouped* menu
Answer: You may always improve the geometry after importing using the Remesh Modifier.

Extrude your mesh downwards to give it some depth. Add the modifier and experiment with the Octree Depth and Scale values.

To see the modifier's effect in Object Mode go to Object header and check the Wire checkbox in the Display panel.

EDIT: Steps to follow in your case:

select thw whole mesh (A) in Edit Mode and press W-->Remove Doubles
with the whole mesh selected press Shift+S-->Cursor to Selected. Enter Object Mode and press Shift+Ctrl+Alt+C-->Origin to 3D Cursor. Then press Shift+C and finally Shift+S-->Selection to Cursor

go to Object header and check the Wire checkbox in the Display panel
extrude your whole mesh downwards (E,Z)
go to Object Mode and add the Remesh Modifier. Increase the Octree Depth and play with a Scale value. Uncheck the Remove Disconnected Pieces checkbox
apply the modifier

delete extruded vertices
select the top ones and scale them (S,Z,0) to make them flat (if needed)

Here's the result:

And a .blend file:
Comment: a file attached problem im getting as soon as the remesh added it disappears
Comment: Updated my answer. Please check it out.
Comment: thanks for replying me and getting that image. as i have notice that 4 image are not similar as i have attach the image/ It looks good from a view but when zoom its not similar.
Comment: Sometimes some modifiers don't work perfectly, so you have to tweak some things by hand. As you have the clean divisions in your mesh, you may try to delete three patterns and give the remaining one an *Array Modifier* with the *Count* number of 4.

importing a good mesh


Can we use PhysX in WebGL?

Question: I'm new to GL stuff (coming in via WebGL, with no direct OpenGL experience). Can we use PhysX with WebGL?
Answer: PhysX is a C++ API and can thus not directly be integrated with the JavaScript-based WebGL.
Depending on your needs, you have the following options:

Use a JavaScript-based physics engine, mostly suitable for 2D use cases.
Use a Game Engine that can export for the web (e.g. Unity 3D) and build your application in there, using full 3D physics capability. Keep in mind that this will probably require your users to install some additional Web Player and is not native WebGL.

Keep in mind that Game Engines may be a viable way for 2D applications too and can make your life a whole lot easier.
Comment: Unity can export to WebGL.
Comment: Why are JavaScript-based physics engines "mostly suitable for 2D use cases"? Also you said "Keep in mind that Game Engines may be a viable way for 2D applications too and can make your life a whole lot easier", which is why I'm making http://github.com/infamous/infamous (renaming it soon and adding docs/demos). It's a 3D API that currently renders to DOM (CSS3D with my DOMMatrix polyfill), and I'd like to add WebGL soon. Here's a couple small demos: http://trusktr.io (hover on the left edge for the 3D menu) and http://mightydevs.com (letters moving into formation, needs word wrapping).
Comment: @trusktr Because, or at least that's what I thought, there is no JS 3D physics engine that comes close to PhysX in terms of features. Then again I just found out that someone [ported Bullet to JS](https://github.com/kripken/ammo.js). YMMV.

Can we use PhysX in WebGL?


Does watching videos have the same bandwidth consumption as downloading a video?

Question: If a video/movie/music video is uploaded to Youtube & provided for download (both are the same files), would watching it (streaming) have the same equivalent bandwidth usage as downloading it?
Answer: That depends in what quality your are downloading and streaming it, but if they are the same the downloaded data will be equivalent. If of course you will watch till the end.
Answer: Yes.
Since you are downloading the video either way, it would use the same bandwidth.  A streaming video is in a format that you can watch AS you download, when combined with buffering.  Buffering, as you may know is the downloading of a small portion before the video actually starts.  It works when you are using an internet connection that will allow you to download the entire video faster than it would take to watch it.  Thus, attempting to watch a streaming video that is HD, on a slow internet connection, would result in the movie pausing frequently, so that the buffer could load another section for you to watch.
But, either way, assuming you are downloading the movie from the same source, it would use the same bandwidth.
Of course, if you choose to stream a video at a low quality, and choose to download the same movie at a higher quality, the end file size of the two would be different.  The higher quality would be larger, and would thus require more bandwidth.
The only time where the length of time/bandwidth might vary, would be if the streaming server was only going to ALLOW you to download the data while streaming at a max speed that was based on the quality of the movie... IE allowing a low quality movie to only be downloaded at a lower speed while streamed, to conserve bandwidth on the server end, but to otherwise allow a "downloaded" movie (not streamed, if you were given a choice) to download at the fastest speed available.


Are QMC calculations practical for periodic structure calculations?

Question: Even some DFT methods or beyond DFT methods such as MP2 calculations are computationally very expensive today even with clusters. If you compare QMC (quantum monte carlo) calculations with them, are the QMC calculations way too much expensive? Is it worth to invest time in QMC?
Comment: Quantum monte carlo probably?
Comment: What's the meaning of QMC?
Answer: Quantum Monte Carlo (QMC) calculations in various forms, for example variational QMC or diffusion QMC have been used to study periodic systems for decades. In most cases, they provide results that are more accurate than DFT, so it is often taken as a reference for solid state calculations. Indeed, the pioneering QMC calculations of the electron gas by Ceperley and Alder (see here) form the basis of common approximations to exchange correlation functionals, so in a sense enable DFT.
So is it worth investing time in QMC? The method is still computationally more expensive than DFT, so the answer depends. If the system/property you are interested in is well-described by DFT (e.g. weak correlations) then there is no point in doing QMC calculations. However, if you need higher accuracy, there is a definite case for using QMC methods. Another point to consider for the longer term is that many QMC methods are trivially parallelizable, so they are capable of making full use of modern computer architectures, which means that they will probably become increasingly pervasive.
The go-to review article of the use of QMC methods to study solids by Matthew Foulkes and co-workers can be found here.
This is a list of codes that implement QMC calculations for solids that are widely used (feel free to add more):

CASINO: https://vallico.net/casinoqmc/
QMCPACK: https://qmcpack.org
QWalk: http://qwalk.github.io/mainline/
Comment: @Alfred I think it is very difficult to put a number to this. I suspect the answer will strongly depend on the system, and on top of that QMC is a stochastic technique, so the answer will also depend on the size of error bar that you aim for. Another big variable are the computational resources available: QMC scales very well, while standard DFT doesn't, so depending on how many cores you can throw at the problem the answer will again vary. Another issue to consider is that QMC is not as "black-box" as DFT at present, so there will be a steep learning curve...
Comment: Thanks for the nice answer. I have a question, how much is expensive than DFT? Is there a ratio or something that you can say? I need it for reference calculations. How many core and memory would make it possible for TMDC's ground state energy calculation
Comment: Thanks for the answer. Now it's more precise, but I have one short question, and I think it'll give me an idea. Is it computationally expensive than the MP2 and ACFDT/RPA methods? If you would choose between them for reference calculation, which one you would choose?
Comment: @Alfred, unfortunately I have no experience in MP2 or ACDFT/RPA methods, so cannot answer. However, this looks like something that the larger community could help with, so perhaps you could ask it as a new question?


How to activate feature using powershell script?

Question: I need to activate specific feature to all site collection which is inside the  particular web application using powershell script?
Answer: Get-SPWebApplication xxx | Get-SPSite -Limit ALL | % {Enable-SPFeature "xxx" -Url $_.Url}
Comment: small tip: use a GUID instead 'name' - it's more precise and less prone to error if there are similar feature names..
Comment: Get-SPWebApplication "Web App URL"| Get-SPSite -Limit ALL | % {Enable-SPFeature "Feature GUID" -Url $_.Url} Is my parameter correct?.I am missing anything?
Comment: Seems right. Usually I'd use Feature foldername but Guid is OK
Comment: Name is a lot easier to read and as it ALWAYS are something like Company.Product.Solution[.SubFeature] there will never be a collision. GUID may be a bit faster, but activating/deactivating features using PowerShell is not where you get performance problems
Answer: Try this,
$site = Get-SPSite http://yourserver
$site | Get-SPWeb -limit all | ForEach-Object {Enable-SPFeature -Identity "FeatureName" -Url $_.Url}
$site.Dispose()
Answer: Per is spot on with the command, however I was receiving an error "The Feature is not a Farm Level Feature..."
Found the answer at http://rajeshch999.blogspot.com/2012/07/powerdhell-feature-is-not-farm-level.html. The feature name was different than the name of the wsp that I installed, looking up the name in the 14 hive made it work for me.
Also, I put it into a short script for ready access if I needed it again.
# Enable-SPFeatureOnWebApplication.ps1
# script to turn on a feature on all site collections on a web app
# look-up feature name in 14 hive if not working

$waURL = "https://your.url"
$featureName = "your.feature.name"

Get-SPWebApplication $waURL | Get-SPSite -Limit ALL | % {Enable-SPFeature $featureName -Url $_.Url}

Answer: other method:
http://www.stefanopaterno.com/post/2011/11/15/Pillole-di-SharePoint-Management-Shell.aspx
Comment: -1 for linking your own (non-English) blog article that contains only one stsadm command that doesn't answer this question (PowerShell command is needed)
Comment: Thanks for the -1 is right, I was racing and I was hoping it would be useful.


Is there common ground between the Tao Te Ching and Buddhism?

Question: I am interested in Buddhism and the book Tao Te Ching, written by Lao-Tzu in c. 600 BC. Is there common ground between these two Eastern philosophies?
link to audio of Tao Te Ching
Comment: Commenting because this is not worth being a full-blown answer, but I'll refer you to the *superb* [Great Minds of the Eastern Tradition](http://www.thegreatcourses.com/courses/great-minds-of-the-eastern-intellectual-tradition.html?cid=4620) audible course. It's usually expensive but is currently on sale for under $50 (e.g. at audible.com). Suffice to say that there are *extensive* cross connections between Buddhism and Daoism, and this course explain them in a really accessible way.
Comment: @tkp Can I thank you for the great minds recommendation. Have just bought it and listened to the  first few. Fantastic. Very cheap if you can get it as part of the audible.com intro offer
Comment: You might also consider Frithjof Schuon's 'Transcendent Unity of Religion'. Philosophical Taoism endorses the same neutral metaphysical description of Reality as Nagarjuna. This is made clear by Lao Tu's comment 'True worlds seem paradoxical'.     .
Answer: There is common ground. But there is common ground between Christianity and Buddhism, too. So...
A commentator of the Taoist philosopher Guo Xiang's work and a Taoist himself, I forget his name now (I can look it up) once wrote that - I paraphrase from memory - Buddhism and Taoism are diametrically opposed, because one seeks detachment from all existence, while the other seeks attachment to all existence. One seeks liberation by detaching from all phenomena, while the other seeks liberation by becoming one with all phenomena. The two paths seem to be the same, but really they are opposite.
Your question is broad, and so it's hard to answer. There are just too many sects... some Chinese ones like Huayan were influenced by Taoist philosophy so there is more common grounds... and then there are Taoist sects that were significantly influenced by Buddhism, like the Quanzhen School...
In the Pure Land tradition, the great patriarch Tan-Luan, was initially a Taoist teacher. He wanted immortality but couldn't achieve it. Then he met the Indian Bodhiruci who gave him the Infinite Life Sutra, and Tan-Luan was so delighted by this sutra that he burned all his Taoist texts and followed Buddhism alone. If this story is true, then we can say at least one person didn't think the two were compatible. Tan-Luan sought immortality, but it occurred to him that when Taoism speaks of immortality, it does so from a point of view of attachment to existence, while Buddhism's ultimate point is nirvana which is neither-existence-nor-nonexistence (suchness). Something far removed from existence and non-existence.
Comment: I feel you are taking your view of Taoism from limited sources. I've heard Taoists criticise the views you contrast with Buddhism as being incorrect. I'd say a correct view of Taoism and Buddhism allows them to be syncretised. Lao Tsu tells us that existence and non-existence are just as Nagarjuna describes, extreme views to be overcome. The sages all obtain their knowledge from the same place. .  .   .  ,
Answer: I've read that one of the things that Taoism and Buddhism have in common is a sense of the ineffable. The opening lines of the Tao Te Ching go

The Tao that can be spoken is not the eternal Tao.
  The name that can be named is not the eternal name

meaning perhaps that the Tao is beyond words so everything that you read about it ... well that's not the real thing.
Contrast that to the Flower sermon where the Buddha does talk and instead just holds up a flower. When he did this ...

The disciples were greatly confused. Buddha quietly displayed the
  lotus to each of them. In turn, the disciples did their best to
  expound upon the meaning of the flower: what it symbollized, and how
  it fit into the body of Buddha's teaching.

however Mahakasyapa understood and smiled. The Buddha said

"What can be said I have said to you," smiled the Buddha, "and what
  cannot be said, I have given to Mahakashyapa."

So again beyond words.
I don't think it is too much of a stretch to see the Taoist influence within this Chineses Buddhism sutra. Certainly if it isn't a direct influence then it is something that the two religions had in common.
Comment: The first line of the Tao Te Ching seems to me to be saying, among other things, that [the map is not the territory](http://en.wikipedia.org/wiki/Map%E2%80%93territory_relation#.22The_map_is_not_the_territory.22), i.e. that the description or the thing-described is not the thing. Whereas the Flower Sermon is 'direct seeing', i.e. "here is a thing".
Comment: @michau - The first line of the Tao Te Ching tells us that Reality is beyond conceptual fabrications, just as Nagarjuna tells us. When the former says 'True words seem paradoxical' he is telling us that we need to use Nagarujana's method of 'Two Truths' to speak about Reality. The two clearly share exactly the same world-view, as we would expect given their method of enquiry. . . .   . ,
Comment: @ChrisW Where did you get this interpretation from? The first line of the Tao Te Ching doesn't say that. It rather says that "the territory that can be mapped is not the true territory". I don't know what it's supposed to mean, but that seems to be the closest analogy to the map-and-territory metaphor.
Comment: @michau It's just my interpretation. I get it e.g. from the 3rd line, "The nameless is the origin of Heaven and Earth" ... IMO the 'nameless' is the (whole, eternal) thing itself before it's described or analyzed, before things are identified; and the 'named' are the myriad mental 'formations' i.e. the map. Unfortunately I have no special insight into the Tao Te Ching itself: I find it so gnomic that it's only by interpreting it as Buddhist doctrine that I find I can make much intellectual sense of it.
Comment: @ChrisW my lens is science, so I interpret both by it. In the case of "the map is not the territory", it seems to be about [tacit knowledge](https://en.wikipedia.org/wiki/Tacit_knowledge). It's like saying "a YouTube tutorial on car driving is not the driving itself", which in its turn sounds like a zen koan?
Answer: Wuwei, as how I understand it, has these understandings, depending on the context:

You do something because you are born for it and do it without wondering why you need to do or learn how to do it (e.g. trees produce oxygen not because oxygen is needed for animals, but because they need photosynthesis)
When you are doing it you are being present in the moment, and allow life to lead you to something unexpected, yet you do not get confused and unprepared when the unexpected occurs
Your action has been simplified to its most basic parts so it can be accomplished in the most efficient and effortless ways
You don't need to do anything because you see the order from the chaos, and you see the big picture from above
You do something impossible or insane with confidence and fearlessness, because you have the knowledge (e.g. sailing into a storm with a smile)

Therefore, I think while Buddhism is about avoiding attachments to not having sufferings, Daoism is about attaching and having no suffering at all.
Comment: Taoism is also about detachment. There is, after all, only way to transcend suffering.  .
Comment: I think this is just a language game? The concept of wuwei is about detaching to the source of suffering too
Answer: In the Dao De Ching it is stated that:
"Therefore it is said:
He who desireless is found
The spiritual of the world will sound.
But he who by desire is bound
Sees the mere shell of things around."
One whose mind is filled with desire only sees the surface of things as they really are. A mind filled with desire sees the world as something to be controlled and used as tools or means for achieving one's will. And so, the mind does not understand that nature, in its deep mystery, is beyond the scope of language and reason.
The world does not need to be controlled, but the mind to be tamed. The wise one understand the changing and ever flowing rhythms of nature, and let's him/herself to go with it: that is Wu-Wei, or effortless action.
Early Buddhism and Daoism (as expressed in the DDC) point to desire/greed and instrumentalization of nature/the world (as defined in SN 35.116) as the causes for unbinding with the Tao/Samsara.
Have a wonderful day!


How to save chat logs in Messages for Mountain Lion?

Question: I always used to save my Chat logs because I use IM in the professional environment. Now I find that I can't save chat logs anymore. That option is gone. Is there any workaround or hidden preference to enable saving chat logs again?
Answer: In Preferences, select Messages and check "Save history when conversations are closed." Now when you quit Messages, it will create a collection of chat transcripts. You can easily access these in your Library folder. From Finder, select Go>Go to Folder and type: ~/Library/Messages/Archive. If you are on Mavericks or Yosemite, the location is ~/Library/Containers/com.apple.iChat/Data/Library/Messages. This will take you directly to the appropriate folder.
Comment: The images are stored in the "Attachments" folder, which is a sibling to "Archive".
Comment: I did this, and it does work but only with text. Do you know if there's anyway to have Messages save any images/files sent over chat?
Comment: Thank you *so, so* much. I had feared this awesome feature from iChat was gone forever.
Answer: Please note that the new location for logs in Mavericks is ~/Library/Containers/com.apple.iChat/Data/Library/Messages (yes, even though the app is called Messages, the container is called iChat).
This appears to be a way of replicating the way that apps like iMessages work on iOS -- Messages gets its own Library folder with its own dedicated hierarchy of files.
Update: At some point after 10.9 Mavericks and by the time of 10.15 Catalina, the real location for stored chat logs became ~/Library/Messages/Archive.
Answer: I don't know if you are still looking for an answer to this, but it looks like you can use Automator (in Applications) to copy all files to a certain folder when items are added to the Archive Folder us "Folder Action".  I am trying it out now, but seems it should work.
Comment: Do come back and flesh this out with edits as you find it works or does not work. Welcome to the site!
Answer: In addition to native Automator, if you're a Hazel or Alfred user they can give you other ways to do this on addition of a file to a folder.
Comment: Can you provide concrete examples or steps how to actually achieve this with the aforementioned applications?
Comment: In Hazel, you could create a folder rule for ~/Library/Messages/Attachments that would, for instance, catch new files added there and tag or move them according to the criteria of interest to you.  Do you have a use case?  If so, I may be able to help you craft a Hazel rule.
Answer: I had the same problem.
On my machine I resolved the problem by removing the Archive link.
Open Messages and send a message. Close Messages. This should now create the Archive folder.
I copied my older chats to this new Archive folder, and everything worked for me.
cp -r /Users//Documents/iChats/ /Users//Library/Containers/com.apple.ichat/Data/Library/Messages/Archive
Answer: If you want the easiest, most foolproof way to do this with the most flexible format WITH images/videos/gifs/emoji/allthethings, follow along. This method contains absolutely zero automation, so even your hip grandma can follow along.

Open the Messages app
Open the conversation you want to copy and keep scrolling to the top to load more of the conversation until you've loaded all that you want.
Select all (Cmd+A)
Copy (Cmd+C)
Open TextEdit and start a New Document
Paste (Cmd+V)

As you can see, all of the text and media are there, and you can edit it like any word file. Want it as a PDF? Just Export to PDF, and it won't even break pages in the middle of images and stuff (as would printing to PDF from the Messages app). Make sure you save this file somewhere before proceeding to the extra step below: resizing photos.
If your transcript contains gargantuan 3648x2736 images like mine do, you're going to want to reduce their size to fit in the document. This is simple: the image data is saved as part of the document. So, just...

Double-click the image you want to reduce to open it in Preview
Once in Preview, select (from the menu bar) Tools > Adjust Size
By default, the Width value is selected and the dimensions are constrained (meaning changing one will adjust the other to keep it in the current Height/Width ratio) as depicted by the little locked padlock icon nearby. Enter a more sane value; I like to go with 640x480 for my images. If you're savvy, move to step 4. If you have no idea what value to enter... First make sure the little padlock icon is 'locked'. If it isn't, click on it and it should become locked. Next, select the larger of the two values (double-clicking on it will fully select), delete the value, and then enter 640. Press ENTER or click the OK button at the bottom.
Your image should now be reduced in size, and you can close the window (Cmd+W), quit (Cmd+Q), or whatever (Cmd+????????)
You should be back in your text document and the image size will have updated. Note: The one anything thing here is that TextEdit likes to scroll you all the way to the top of the document. Them's the breaks.

There you have it. Chat transcript archived like a boss.
Comment: It allows to check back the messages with a Mac but not a proper manner to have the sync across other iDevices… Which is by the way a pain because it's one of the rare things that are not synced via the "iCloud Drive" nor visible via iCloud.com.
Comment: PS: High Sierra MacOS 10.13 has an option in iMessage account preferences to "Enable Message in Cloud"


When did the appearance of the quarter rest in music change from its original appearance?

Question: WHEN did the appearance of the quarter rest in music change from its original appearance — as a backward looking number 7 () to its current look ()?
I have been searching the Internet with no luck. I know the original quarter rest looked like a backward eighth rest, so the design was changed completely. I just cannot find anywhere WHEN the change took place. It would also be nice to know WHO decided on the change.
Answer: I have "researched" quite a bit and collected some interesting examples, see below. As can be seen, we have a huge geographical impact, France (I have numerous additional examples) seemed especially fond of the backward-7 notation, keeping it up to the middle of 19th century, while the Bach autograph from ca. 1723-1730, the Walsh print of 1795 and the Liszt-Diabelli example I added to the Sqiggly-symbol question point to earlier migration to a new symbol decades or even a century earlier.
Jancourt print 1849:

Bach autograph, ca. 1723-1730:

Walsh print, unknown composer, 1795:
Comment: @Barbara53: You are welcome, actually the currency here on stack exchange is upvoting and accepting ;)
Comment: That Walsh print is one of the clearest intermediates I've seen. On the one hand, it very nearly looks like a modern rest, slightly tilted to the side, but on the other hand, the check mark, upstroke, and curved cross-bar are all still visible.
Comment: This is EXCELLENT RESEARCH! THANK YOU sooo much for your time, effort, and insight!  It IS appreciated!
Answer: Possible duplicate of: Origin of the 'squigly line' used for quarter note rest?
There are several scans of manuscripts (from Corelli to Mahler) linked from that page that show many intermediate forms. It seems to have been a gradual evolution due to handwriting, rather than a dictatorial all-at-once change. In addition, each composer had their own handwriting, of course.
As a whole, they show that the backwards-7 quarter rest gained a 'check mark' on the bottom, in addition to the upstroke and crossbar. The upstroke got slanted in various directions, and the crossbar became curved, which can create a form closely resembling the modern form.
What, unfortunately, hasn't quite been demonstrated on that page is the final step from the modified squiggle to the modern printed form. For that answer, I think you'll have to look at the history of music printing, and see what symbols were being used by the publishing houses, printing presses, and "music typewriters". This page might provide a good jumping off point.


How to authenticate a user in a RESTful api and get their user id? (Tornado)

Question: I would like to maintain statelessness but I also don't want to call my login function on each authenticated request.  Would using tornado's secure cookie functionality be feasible for storing the userid in each request for a mobile app?  I'm trying to keep performance in mind, so although basic http authentication would work, I dont want to call a login function on each request to get the users id.
Answer: I am assuming that your authentication function talks to a database and that each page in you app hits the database one or more times.
With that in mind, you should probably just authenticate each request. Many cloud/web applications have multiple database queries per page and run just fine. So when performance does get to be problem in your app (it probably won't for a long time), you'll likely already have an average of n queries per page where n is greater than 1. You can either work on bringing down that average or work on making those queries faster.


Can not Copy from a Pdf Document

Question: I am using Adobe Reader and Preview in mac to read a book in pdf format but I couldn't able to copy any word in the book. I don't understand what is different in this case because I have always done that on a pdf document so far. Any help would be great. Thanks
Comment: It's probably an image-based, rather than a text-based, PDF, meaning that there is no text embedded in the document and it's basically just a photo of text.
Answer: This sounds most likely that the document has been scanned, and then not processed with OCR (Optical Character Recognition).
Just with Adobe Reader and Preview.app, you can not do much about it. In order to make it copyable, you would have to get OCR software, or if you have access to Acrobat, use its OCR capability.
There may also be some security settings with the file; you can see that by opening it in Adobe Reader, press  to display the document properties, and then select the Security tab.
Comment: Thanks a lot. I couldn't able to via google drive since the size of my book is big but I was able to use Adobe acrobat to convert the pdf to a format that I can copy it now. Unfortunately there is no free OCR software, I have just started to use one month free trial for Acrobat. But thanks again.
Answer: Max is right, but there are online tools that will do the OCR for you as well. One referenced here, is Google Docs.
http://computers.tutsplus.com/tutorials/how-to-ocr-documents-for-free-in-google-drive--cms-20460
Seems pretty straight forward, but if you have any questions, let me know.

Can not Copy from a Pdf Document


What is the difference between the Linux Kernel and the Android Kernel?

Question: What are the modifications done in linux kernel to make it an android kernel ? By this question I mean what are the differences between linux kernel and android kernel ?
Comment: Related: [What linux distribution is Android based on?](http://android.stackexchange.com/questions/4339),  [Which Android runs which Linux kernel?](http://android.stackexchange.com/questions/51651/) and [Why are there so many different Android kernels](http://android.stackexchange.com/questions/27395/)
Answer: I think this Android Source is a great documentation for understanding it.
And here is a list of changes done from mainline kernel for android kernel 4.14.
The largest features include:

19.8% Energy Aware Scheduling (kernel/sched)
13.8% Networking (net/netfilter)
13.5% Sdcardfs (fs/sdcardfs)
9.4% USB (drivers/usb)
7.2% SoC (arch/arm64, arch/x86)
6.2% f2fs (fs/f2fs -- backports from upstream)
6.1% Input (drivers/input/misc)
5.4% FIQ Debugger (drivers/staging/android/fiq_debugger)
3.6% Goldfish Emulator (drivers/platform/goldfish)
3.4% Verity (drivers/md)
11.6% Other

Differences from LTS
When compared to LTS (4.14.0), the Android common kernel has 355 changes, 32266 insertions, and 1546 deletions (as of February 2018).
Comment: It is now 2023, how has things changed since?
Answer: The differences change from version to version (both of Linux and of Android), and the exact kernel is different for each device. A kernel for Android is a mainstream Linux kernel, with additional drivers for the specific device, and other additional functionality, such as enhanced power management or faster graphics support.
Many features in the Android kernel are later added to upstream Linux after the open-source community has accepted (and perhaps modified) them, but others are never upstreamed, either because they're not acceptable to the Linux kernel developers, or because they're only applicable to Android or to specific hardware.
Comment: Most drivers for android specific hardware was accepted into mainline kernel; but some features, such as the wake lock which caused a huge controversy some time ago, remains problematic because mainline and android kernel developer disagree whether it's a good idea.
Comment: " A kernel for Android is a mainstream Linux kernel, with additional drivers for the specific device, and other additional functionality, such as enhanced power management or faster graphics support", so it's mainly drivers? No source code changed?
Comment: @GuerlandoOCs I'm not sure what you think drivers are if not a source code change, but regardless, the "other additional functionality" I mentioned is quite big these days. There are many source code changes.
Comment: @DanHulme are the source changes patches or just code changed by hand? How can I see things that changed? I've read that you can patch your linux kernel to be compatible with android, but where are those patches so I can read them?
Answer: Beside the device specific differences and wake lock that Dan Hulme and Lie Ryan mentions, Android removed System V IPC features (message queues, shared memory segments, semaphores) that could lead to resource leaks (http://www.kandroid.org/ndk/docs/system/libc/SYSV-IPC.html). This probably is just a matter of configuring the kernel build. Also the Android IPC of choice, called Binder, has some support in the kernel that to my knowledge is not included in standard Linux kernels.


What are the effects of camber location in an airfoil?

Question: Am I correct to assume that for a low speed aircraft, the location of the camber in the MAC's airfoil will correspond with the aerodynamic center? Also, does that affect the moment coefficient? And what about a high speed aircraft (M>1)?
Answer:
[Does] the location of the camber in the MAC's airfoil correspond with the aerodynamic center?

No.
The aerodynamic center is where the additional lift force from a change in angle of attack can be summed up. Since camber only determines the lift portion that is independent of angle of attack, changing the camber will not influence the aerodynamic center.
For a high aspect ratio wing in subsonic flow, the aerodynamic center is at the quarter chord position. With decreasing aspect ratio this point moves slowly forward until it arrives at the forward tip for a slender body.
Also, strictly speaking, there is no "location of camber" — camber is distributed over the whole chord. What you probably mean is the highest point of the camber line, but that point has little aerodynamic significance. The local curvature of that line is much more important.

Also, does that affect the moment coefficient?

Yes.
Generally, the more an airfoil is cambered towards its rear end, the higher its pitch moment coefficient will be. This is called "rear loading" and is used in order to combine decent thickness with good lift in transsonic airfoils. You can use the lengthwise location of the highest point of the camber line as a guide how high the moment coefficient will be.

And what about a high speed aircraft (M>1)?

That depends on wing sweep. Normally, aircraft designers try to keep the wing's leading edge subsonic over the full speed range. But I guess you wonder how the camber will influence a wing's performance once it moves at full supersonic speed. Well, the bad news is that camber will drive up wave drag without any influence on lift. Supersonic aircraft, therefore, use thin airfoils with very little camber, and the camber they have is only there because it helps in subsonic flight.
Answer: No. Generally, for low speed aircrafts, the AC is located around 25%MAC(non-laminar airfoils) or 50%MAC(laminar airfoils) which, in both cases, represents the maximum thickness location not the camber(which is the maximum distance between the mean line and the chord line).
AC is the place where de Cm is nearly constant, so you can say the Cm 'doesn't change'. The momemt, obvioulsly will change with the aircraft's attitude, but the coefficient doesn't.
For supersonic flight it's, generally, AC is around 50%MAC.


How to get AdSense on a Google Code project page?

Question: I must admit that I don't really know if this is the right place to ask this question, however: in your knowledge it possible to have AdSense on a Google Code project page? I have tried searching Google for information about this, but it gets very confused by the query (that's because the AdSense API is on Google Code as well!).
Answer: I found this method that allows you to put ad gadgets with AdSense on your Google Code project home and wiki pages: http://code.google.com/p/gprojecthosting-adsense/
It works very well for me, I must say.
Just keep in mind that the gadget renders in an iframe with little if any content, so the relevant ads as inferred by Google will be mostly (or only) interest-based.
Answer: I use this one https://code.google.com/p/gcodeadsense/
works like a charm. Mind this: just use the number from the client code and skip  "ca-pub-".


Are more expensive Protein powders worth it?

Question: Protein powder in general is very helpful in supplementing extra protein intake, especially during a caloric deficit. I typically buy the cheaper stuff since I'm a student, and I never really thought paying twice the price with minimal difference was worth it. Is there really a big difference, like many sales workers try to convince you there is?
Comment: Welcome to the FItness SE! A few point about your question; you have to include what's in the protein powders you want to discuss. Just telling us that they're expensive is far too vague. There's a large variety between different expensive powders, and some of them are expensive for no reason other than a high profit. Also, keep in mind that questions regarding nutrition alone are off-topic here. To avoid close votes, please make sure you angle it towards actual fitness and exercise.
Comment: This is an international community. The powders you might be thinking off are unknown to most people here. Please give us details. I'm from Europe, as far as I know, in the us, because there is less regulation, protein powders are far worse than what we get. Please get specific here. Also, I don't think you are correct in saying that they are a great way to supplement in a cut, but again that's because where I come from, there is actual quality food that offer the same nutritional value - far better even than a lot of the cheap powders. As you can see, it varies a lot. And then there is taste
Comment: I didn't realize that it could vary that much. I thought the price would pretty much determine the product you got for a given type powder (like whey). I know creatine monohydrate is pretty consistent between brands to the point where it makes no difference, is there a big difference between whey products, even in the same price range?

My question is mostly related to diet so I guess I should ask somewhere else?
Comment: "Worth it" is a subjective stance. It also depends on what you're comparing. Are we talking some no-name protein powder vs. a premium whey isolate w/ creatine?
Answer: To give one of my favourite answers... it depends.
As a student, price is probably one of your main concerns, and if they're doing what you want them to do, then stick with the one you're using.
My friend buys his in bulk from either Bulk Powders or MyProtein (UK based), and they do him fine. They help him hit his protein goals and help reduce muscle soreness after a training session.
For myself, I've found that the cheaper brands that he uses can play havoc with my digestive system. I never figured out what it was in them that caused issues, it could be an intolerance to whey, it could be the sweeteners they use in some, it might be that I'm celiac and there's something in the packing process that contaminates them beyond my ability to tolerate. Whatever it is, I pay more for a vegan blend I've found that only uses a few ingredients and causes me no issues. For me, the extra money is worth it.
It could be that you find you can get your protein requirements in by buying cheap cuts of meat (the secret is to cook them for a loooooong time), tinned fish (I'd recommend sardines, not tuna) or cans of chickpeas if you're that way inclined, in which case, the protein powder probably isn't worth it to you.
I'd recommend experimenting (I think most companies do samples of protein powder fairly cheap), you might find that you're willing to pay a little more for one that tastes better.
(Just don't try unflavoured hemp protein, it's honestly one of the most disgusting things I've ever tried to stomach, plus when I dropped some on a tea towel, it bleached the colour out of it. I find that concerning.)
Answer: Firstly it's hard to answer your question based on the information provided as it only asks about higher versus lower prices and not about the types of protein you are looking at. Pricing for any products can be decided for a number of reasons and the most common being perceived value. That being said price alone doesn't necessarily determine the quality of the product especially in the supplement industry with so many competing products all boasting to be the best quality and very few standards that are easily measured by consumers.
As far as my recommendation for protein I would suggest looking at egg based protein powders. Eggs are the most complete form of protein and compared to whey of any quality will be superior as most whey proteins are of cheap quality despite marketing around them. All the best. Stay strong!