Ontario HST Rebate: Filed taxes, but haven't received HST payment for December 2010?

Question: I have still not received my HST refund payment for December 2010.  When can I expect to receive my refund?  I filed my taxes and have just paid my balance of taxes owing, but still have not received my refund cheque that would be a direct deposit.
Comment: See http://money.stackexchange.com/questions/1871/ontario-hst-rebate-confused-about-payment-schedules/1872#1872
Answer: When you say you filed your taxes, did you file your 2009 taxes, or your 2010 taxes?
For the December 2010 payment, you would need to have filed your 2009 taxes.  (Whereas, for the final payment in June 2011, you would need to have filed your 2010 taxes.)
If you only recently filed your 2009 taxes (i.e. filed them late), then it may take up to 8 weeks after your return has been assessed  for your cheque or payment to be issued.  However, if you filed your 2009 taxes after April 30, 2011, you won't get the December 2010 payment.
If it has already been 8 weeks since your 2009 tax return was assessed and you did file by the deadline, then you should call the toll-free enquiries number at 1-877-627-6645:

You'll be calling about the Ontario Sales Tax Transitional Benefit (OSTTB).
You can press 5 when prompted to hear pre-recorded information about the benefit, or, better,
press the star key (*) to speak to an agent.  Mention "OSTTB".  They should be able to help you determine if you did qualify and what happened with your payment.


Why is (NH4)2[CuCl4] square planar complex but Cs2[CuCl4] is tetrahedral?

Question: Why is $\ce{(NH4)2[CuCl4]}$ square planar complex but $\ce{Cs2[CuCl4]}$ is tetrahedral even though both have same oxidation number of copper and same ligands?
Answer: In solution, the $\ce{[CuCl4]}$2- is expected to exhibit terahedral, or nearly tetrahedral geometry.
The Jahn-Teller theorem states that degenerate orbitals cannot be unequally occupied. Molecules with unequally occupied degenerate orbitals will distort so as to render the orbitals non-degenerate, with more electrons occupying the lower energy states. Generally, this distortion leads to a reduction in symmetry. In the case of Cu (II), it is a d9 cation with a tetrahedral electronic configuration of (e)4(t2)5, so the three degenerate t2 orbitals are unequally occupied, therefore a distortion towards the square planar geometry of (eg)4(b2g)2(a1g)2(b1g)1, with no unequally occupied degenerate orbitals, is electronically favoured. Nonetheless, experimental evidence (1) indicates that this d-orbital stabilization energy is very small. Since copper is a first-row transition metal (not very big), steric effects dominate electronic effects allowing $\ce{[CuCl4]}$2- to assume a tetrahedral geometry. Most spectroscopic methods I've read involve looking at the molecule in crystal form (because that is where this effect gets interesting), but DFT studies of the $\ce{[CuCl4]}$2- hydrate in concentrated aqueous solution indicate that the anion's tetrahedral structure is more stable (2).
The issue of $\ce{(Cs)2[CuCl4]}$ vs $\ce{(NH4)2[CuCl4]}$ comes up when the complex precipitates and crystals are formed. Due to the borderline electronic effects, the $\ce{[CuCl4]}$2- anion exhibits a great degree of structural flexibility. With large cations ($\ce{Cs+}$ radius is 0.174 nm while $\ce{NH4+}$ radius is 0.143 nm) , it crystallizes as a distorted ("squashed") tetrahedron.
$\hskip1.4in$ (3)
Square-planar co-coordination occurs in such a way that you effectively get octahedra with tetragonal distortion (4). I would imagine that this phenomenon is simply a result of the smaller cation allowing the unit cell to crystallize like that. The general idea with unit cells is that the cation is never allowed to "rattle" around, so the structure will find a way to fill in the space. Given the preexisting electronic favourability of square planar geometry, $\ce{(NH4)2[CuCl4]}$ this distortion favoured by close-packing is made even more favourable.
$\hskip2.1in$ (4)
The canonical reference for $\ce{(NH4)2[CuCl4]}$ 's crystal structure is (5) if you want to take a look at the unit cell.
(1) Emeléus & Sharpe. Advances in Inorganic Chemistry and Radiochemistry, vol. 21, p. 128
(2) https://www.ncbi.nlm.nih.gov/pubmed/21462945
(3) L. Helmholz & R. F. Kruh, J. Am. Chem. Soc., 1952, 74, 1176
(4) Molecular Structure by Diffraction Methods, vol. 1, The Chemical Society, London, 1973, p. 642
(5) R. D. Willet, J. Chem. Phys., 1964, 1964, 41, 2243
Comment: thanks for pointing out my typos!
Yes, I was describing the extreme cases; the tetrahedral form in solution and the electronically favourable square planar case. In ammonium chlorocuprate's unit cell, the ion's geometry is the intermediate, non-inversion symmetric case. If anyone has access to (5), we could describe its symmetry. Sadly, this volume seems to have been misplaced in my library.
Comment: Haha, my VPN gives me access. The article doesn't include a picture though. To quote the discussion: 'This structure contains the first instane of a square-planar $\ce{CuC4-}$ ion. The $\ce{Cl-Cu-Cl}$ bond angle is required by symmetry to be $90^\circ$. However, the $\ce{Cu-Cl}$ bond lengths are not required to be equal. Two are $2.300 \pm 0.005~\mathrm{A}$ long, and two are $2.332 \pm 0.004~\mathrm{A}$ long. Each copper atom completes its normal distorted octahedral configuration by forming two long $\ce{Cu-Cl}$ bonds of $2.793 \pm 0.005~\mathrm{A}$ with adjacent ions and thus forming an …
Comment: … infinite two-dimensional network. The $\ce{Cu-Cl-Cu}$ bond angle is linear ($180^\circ \pm 0.2^\circ$) to within experimental error.'
Comment: is the bond length distortion due to electronic Jahn-Teller effects (as in http://chemistry.stackexchange.com/questions/43111/jahn-teller-distortions-in-square-planar-complexes), or is it just a consequence of the crystal packing? I have VPN too, but the journal isn't available in electronic format that far back for me
Comment: They unfortunately don't go into detail. I would say that JT doesn't sound unreasonable, but it could also be some weird packing effects. Again, an image is not included, unfortunately.


Should I use a 24-105 or a 70-200 lens for photographing a high school marching band?

Question: Ok, I am an amateur photographer and I will start being the marching band photographer for my high school. I will get a Canon 7d soon, but I'm told it has poor low-light capabilities, which is a problem, because the band always plays at night on the football field under stadium lights. I have been looking for the right lens, and I happened across the Canon 28-105mm L series lens, which is very highly rated, so I'm leaning towards that one. Just to be sure, I asked a friend who is a professional photographer, and he recommended getting a Sigma 70-200 lens instead. I really need a second opinion here!
Answer: I've been shooting high school bands for near a decade now. Your question as asked is hard to answer because there are too many variables you have left out.

What type of photos are you after? Wide angle shots with a large portion of the band or closeups of individual members?
What will your shooting position be? In the stands (how big is the stadium and how far are the stands from the sideline)? From the sideline? From on the field at times?
How many students are in the band? How are their shows written? Do all of the members circulate and spend some time on the front line at some point during the show or do certain sections tend to be placed at the back for most of the show?

Without answers to these types of questions it is hard to give a good answer on what type of lens(es) you will need. However I will share what has worked for me at various stages in my experience.
I started out with a Canon Rebel XTi and two lenses: the EF-S 18-55mm kit lens and an EF-S 55-250. The current 18-55s are much better than the one that came with my XTi (which was horrible), and I replaced it with a Tamron 17-50mm f/2.8 Di II that I used as my "wide" lens until I went Full Frame a few years later. For the wide shots I highly recommend this lens. I got some pretty good stuff with the XTi, the 17-50 and the 55-250.
Rebel Xti and 55-250 @ 154mm, f/5.6, ISO 800, 1/100 second

Rebel XTi and 17-50 @ 39mm, f/4.5, ISO 800, 1/100 second

Being (self) limited to ISO 800 forced me to use slower shutter speeds than I would have liked. I had to take a lot of pictures and work on timing them perfectly to get a few that were timed so that the motion blur was minimized.
By the third season I had picked up a Canon 50D and an EF 70-200mm f/2.8 L IS II. It was like walking out of the darkness and into the light! The camera handled much faster allowing me to catch more shots I would have previously missed and the fast, high quality telephoto allowed me to shoot at faster shutter speeds.
If you are going to limit yourself to only one lens, a 70-200mm f/2.8 is probably the one you want. You can shoot (from the sideline) closeups of students near your shooting position, full body shots of students out to about the nearest hash mark, and also (from the stands) wider shots of groups of students such as a particular section. Get the best one you can afford. IS is nice, but not essential, especially if you practice good camera stabilization techniques and/or shoot from a monopod. If the choice is between a 70-200 f/4 IS and a 70-200 f/2.8 (no IS), go with the faster aperture! I've gotten a lot of nice shots with the 50D (and later the 7D and 5DIII) plus the EF 70-200mm f/2.8 L IS II!
This one was from the very first time I shot with the new lens.
Canon 50D and EF 70-200mm f/2.8 @ 120mm, ISO 800, f/2.8, 1/200 second. It has been slightly cropped. In the full resolution version you can see the weave of the mesh on her shoulder!

The faster telephoto lens allowed me to shoot at faster shutter speeds that enabled me to get shots I couldn't before and along with the better AF system of the 50D and the better optical performance of that amazing lens I was able to capture many more "keepers" than before. I continued to use the XTi and Tamron 17-50mm f/2.8 for my wide shots. With wide shots the shutter speeds are less critical, since the same movement at the same distance produces less blur. Using two bodies allows me to change from long to wide and back almost instantly.
I currently shoot with a recently acquired 7DII + the 70-200 (still a great lens). The AF system of the 7DII is much more consistent than my 7D (it replaced the 50D after about 3 years of heavy use). I'm looking forward to seeing how well the "anti-flicker" feature of the 7DII works with typical high school stadium lighting.
(Update: The new anti-flicker feature Canon introduced with the 7D Mark II is very nice and almost revolutionary for this use case. Not only does it give much more uniform brightness and color in each frame when shooting under flickering stadium lights which has dramatically increased my "keeper ratio", but since it always releases the shutter at the peak of the lights' cycle I can shoot about 2/3 stop faster than I could under the same lights with the same ISO and Av as before! Note that when shooting wide enough that light from more than one tower is in the scene if the towers are out of phase with each other then it doesn't work as well, but it still does better than without the anti-flicker feature.)
I now use a 5DIII for my wide body (the first season I had it I alternated it and the 7D with the 70-200) and depending on what I am going for usually use either an EF 17-40mm f/4 L or a 24-105mm f/4 L IS. Sometimes I'll also add a 5DII and a 50mm f/1.4 or 100mm f/2 into the mix, but I prefer two bodies unless I have a specific shot in mind that only the fast primes can get me.
EOS 5DIII and EF 17-40mm f/4 @ 17mm, f/4, ISO 1250, 1/200 second.

Okay, I cheated! This shot was from the practice tower during a full dress run before a game during mid-October. The sky was overcast and sunset was just a few precious minutes away.
Here's a shot from the stands at a competition in the late afternoon with an overcast sky. Canon 5DII and EF 24-105 @ 35mm, f/8, ISO 160, 1/500 second and a lot of post processing including tone mapping a single raw file.

The full frame bodies along with my increased experience dealing with noise in post processing has really allowed me to push the ISO in recent years. I'm no longer afraid to routinely shoot at ISO 2500 and even ISO 5000 with the FF bodies when the situation dictates it. I'll go as high as ISO 3200 with the APS-C bodies (avoid the +1/3 stop ISO settings on recent Canons: 125, 250, 500, 1000, etc). This allows faster shutter speeds and, along with the better AF performance of my current gear, greatly increases my "keeper rate" from the days when I was starting out.
Beyond the gear, here are a few tips based on my experience:

Shoot as many closeups as you can during the early season when there is still some daylight at the beginning of the game. If your band does an on-the-field pregame, you can get a lot of good shots when they are playing while standing at attention and not moving during the national anthem. The extra light will allow you to reduce the ISO setting and still get faster shutter speeds (1/250-1/500 second or faster).
Don't wait until the show starts. When the students are on the field and lined up ready to begin, they are standing still and you can get some lower shutter speed shots.
Don't just shoot the show! Get shots of them from the time they arrive to the time they go home. Lining up to march into the stadium, playing songs in the stands, warming up for halftime, marching out of the stadium, at practice, etc.
Change your shooting position from one performance to the next. If you can catch a practice or two, work out a shot list for each shooting position. Actually take shots from the possible shooting position while at the practice and then revue them before you shoot the show from that spot to see which angles work for which parts of the show.
Learn the show! The more you know what is going to happen next, the better you can plan ahead and get better shots. It allows you to be proactive in your approach rather than reactive. Develop a list of shots you want to capture at each performance, but also look for interesting things that you haven't noticed before.
Develop a good working relationship with the band director. The more the director trusts you, the more access you will have to everything going on. I have even shot parts of shows from in the middle of the band on the field! In those cases I always attend a rehearsal and plan and rehearse my movements along with the band. Not only does this allow you to know where you can and can't move at a particular spot in the show, but it allows the students to be confident that you won't get in their way. It helps to do this later in the season when both you and the students already know the show fairly well. Even if you don't get in the middle of the band, you can still shoot from the edges on the left and right if you know exactly how far they will come towards you before they turn and go a different direction, or shoot from a low position behind the pit!
To effectively use a wider angle lens, such as the EF 24-105mm f/4 L IS, for anything other than large group shots, you're going to need to shoot from positions very close to the performers. If you won't have that kind of access, then a wide angle lens should not be your only or primary lens, but can be quite effective as a second lens.
To show just a bit of motion with the guard and percussion section use a shutter speed of around 1/160 to 1/250 second. You can freeze the face and torso while seeing a little motion in the hands and flags, sabres, rifles, drumsticks, mallets, etc.

Canon 5DII and 17-40mm @ 17mm, f/4, ISO 2500, 1/250 second from a kneeling position behind the pit (on the sideline out of view from the folks in the stands).

Canon 5DIII and 70-200 f/2.8 @ 200mm, f/2.8, ISO 1250, 1/160 second from a standing position on the 30 yard line at about the first hash mark (outside the band's formation, but on the field)

Canon 5DII and 24-105 f/4 @24mm, f/4, ISO 3200, 1/200 second from about the goal line and halfway between the sideline and the near hash mark. The stadium we were visiting only has four light towers centered over the 10 yard lines so the middle of the field is about 1-2 stops darker than the ends of the field. The band had a show that included a guard segment down near one of the end zones, so I planned and shot the show from that angle in that stadium and used the unique lighting to my advantage.
Comment: Great Shots. Not easy to capture Marching Bands. I've been trying for years and I have to agree:
1) No the Show if possible.
2) Keep your eye on the prize (Which member you are shooting)
3) Watch your ISO when possible.
Comment: Since moving to all constant aperture lenses in 2010 I almost always shoot halftime in **M** exposure mode, so ISO, Tv, and Av are locked in once I dial them in for whatever stadium we're located. I also shoot raw so I can fully control the color in post, so the normal exposure differences from one part of a field to another aren't much of an issue.
Answer: You're pretty much comparing apples and oranges here - the 24-105 and 70-200 cover very different focal length ranges. You need to get a lens which covers the range of focal lengths you're going to need.
That obviously transforms the question into "what focal length do I need?" - and the answer to that depends on where you're going to be standing relative to the band. If you're going to be standing on the sidelines and trying to get a shot of the whole band standing in near you, then you're going to want something like the 24-105; if the band is on the other side of the field and you're trying to get a shot of one individual member, you're going to want 200mm or longer.
Answer: If you photograph a Whole band then the 70-200 might be a no go.. You need to know how many people there are and be sure that you dont have to be too far away to get everybody in. So probably the 28-105 is a better option if your choice is between these two. Yesterday i photographed a couple, full body with the 70-200 and had to stay 20 meters away to get TWO (2!!) people in the shot. Another lense i would consider is the 24-70mm f2.8. If the canon is too expensive then you can go for the tamron alternative. It costs a lot less and the quality loss compared to the canon is very minimal, especially if you are an amateur photographer.
Go for a bright/fast lens, and if possible with a big diameter to gather as much light as possible. I want to get the 24-70 tamron myself as its a very good lense for a good price.
Answer: I would take a 70-200mm with f/2.8 and image stabilization.
It could be like Canon EF 70-200mm f/2.8L IS II USM but such lenses are very expensive.
Scott Kelby has a lot of articles concerning photography on stadium in his blog.
For example: Shots from my first football shoot of the season
Comment: Kelby shoots in stadiums that have lights that are about two-three stops brighter and don't flicker compared to most high school facilities.


Exact difference between User Centered Design and Consumer Centered Design?

Question: Would like to know what differentiates consumer centered design from other design approaches eg. user centered design. What are the additional key elements that need to be addressed. Would be delighted to hear a comprehensive answer with an approach and methodology.
Comment: I disagree. When you read the phrase "consumer satisfaction" you are likely reading about a group or demographic that spans across all businesses in a segment. When you read about "customer satisfaction" you are likely reading about all customers of a business, regardless of demographic. "Customer" is more narrow than "consumer." Think of "consumer" as "a citizen spending money" and a "customer" as "a person giving me money for my product." I think your question is about "customer-centered design" and you might get more answers if you rephrased your question.
Comment: Do you mean cus_t_omer centered design? Your title and text reference "consumer centered design" without a "t." In the field of UX and IxD, I have not heard the term "consumer centered design." If you intended the latter, could you provide some links?
Comment: Yes, I guess both mean the same and are interchangeable terms.
Comment: if the user is the consumer, then I imagine it's one and the same.
Comment: @mawcsco based on that explanation, I think this is probably more of an english.sx question more than UX. ;)
Comment: Does anybody else get really tired of seeing "UCD vs -centered design"?  Most of these X-centered design phrases are little more than buzzwords.
Answer: You could think of Customer Centered Design as an inherited subset of User Centered Design. That means that you do not address only user in an anonymous way, but the user is also a customer. A more targeted user group always have the benefit that you can more fine grained find out the actual target, such as task completion, in this case finding things to buy, and subsequently buy them.
Customer Centered Design is really a Contextual Design of User Centered Design.
Reference: Wikipedia – User Centered Design, UCD models and approaches
Answer: Let me try and shed some light on this. Customer Centered Design is understanding the experience before and after the customer (user) engages with the product. User Centered Design is really about the experience in the moment of the product.
Hope that helps
Answer: Here are my thoughts...
customer centered Design would depend mostly on the requirements from the audience using the system and what the system is designed to do, and User Centered would rely mostly on the science and behaviors colors, layout and functionality....
Comment: Could you elaborate on this a bit. As it is its more of a comment than an answer.
Comment: It would depend on the functionality, purpose of what your are designing to the system to do. (Functionality, scope, Purpose and Usability).
Answer: Design thinking in itself lends to the aspect of creating mental models that go into processing a design solution.  You're question is one that begs to be answered as to why there isn't a wiki on consumer design.  Should there be?  Perhaps.  User-experience and Customer-experience weren't part of the vocabulary years ago either.
There are several other methods of course, but you asked about the difference between consumer and user experience.
If you are in marketing or product design, you will be focusing more on the consumer experience than user-experience.  You want to build a better mouse trap that draws in potential customers.  That is what we are getting at, so this is a valid point of the OP (original poster).
Of course user-experience is about the user.  Can a user be a customer or consumer?  of course..  so this logic has to be that a consumer is a subset of the user-experience.  But hold on, what if its referring to a car dealership or shop without an online presence...  heh.  Okay, but we're not talking about anything non-software for this argument, ok? :)
As for the customer experience (cx) : can it be interchangeable with consumer experience?  Sure - some could argue that point is merely semantics. But when you drill down into other thought leaders, you may see that consumer experience is the ACT OR PROCESS OF PURCHASING, while customer experience defines as a person who has already bought something.  I saw this intellectual battle rage with leadership teams at major corporations on this exact same war of semantics.  The war continues...


Are the deb files stored in /var/cache important?

Question: I have nearly 800 MB of .deb files in cache folder ....
I went through other posts related to this query but I wan not convinced.
Should I just save all theses files somewhere ?
I guess it won't affect anything !!
Answer: No, they are not important.
You can remove them safely.
Those files are just like the name says cached for later use.
That means that if you installed some software and later removed it, you do not need to download the package again,but just install it from local debian package.
To clear the whole cache use
sudo apt-get clean

Answer: These files are no timportant unless you want to repeatedly remove and reinstall packages and not download them again.
Type
sudo apt-get autoclean

to get rid of them.


In terms of Game Design, is the definition more of designing the ENTIRE game, or can it be limited to contributing to the artwork?

Question: I am a person who desires a job in the artwork development of a video game, but the exact term for the general career often confuses me. What I want to do is Character Design, but what general career does it fall under in terms of video games? Is the overall concept Game Design, or is it just Illustration? I get confused that Game Design is just creating the ENTIRE game from the top of your head and not just a specific area of the development, like the art. Am I wrong? Does Game Design work for both the idea and the artwork, and can the term be separated between the two? A helpful answer would be much appreciated.
Answer: What is a Game Designer?
A game designer designs games. More specifically, they design the rules of the game, and how the player interacts with the game. They design the way Mario's physics work, they design the rules of jumping on Goomba's heads, and they design the levels in such a way that the player is forced to learn about Goomba-head-jumping-physics.
To do any work for a game, it would be helpful to know a little about Game Design. A Character Designer would benefit from understanding how the atheistics of the games effect game-play. For example, you don't want the player to confuse Goombas for One-Ups.
Answer: When I hear game designer, I think of somebody who thinks up game mechanics, freedoms and constraints, level designs, balance etc. The may well have no part in actually programming the game. What you are is a game artist.
That doesn't mean that you can't have more than one role in creating a game, and at the same time each role influences every other role significantly. At any rate, you are a game developer, as are programmers, testers, sound engineers, etc.
Answer: Game Designers
In developing a game, anyone who is part of implementing the game is to some degree a game designer:
A developer writing code for a random event for example. Original versions of Tetris had completely random choice in pieces (waiting forever for a long piece). While some newer versions use a grab bag approach.  While it's still random, it means that for every X pieces (size of the bag) you'll get at least 2 long pieces. A simple example of how a programmer decides to implement random affecting the game design.
Artists (models, texture, lighting) all have an effect on how the game looks. If an item is hard to see among other elements or does it really stick out. That changes the feel of the game. Is it now a matter of intensely inspecting the world around you, or just quick scan, there's the next pick up.
So a Game Designer is the one responsible for the overall vision and interaction of all these small pieces.  A game designer might make a statement, "we want the pieces to be random" vs. "we want the pieces to be random, but want to prevent an extreme wait for a long piece".  Or "these types of pickups should be easy to identify, but these special collectibles should require careful inspection of the environment".
Game Designers are responsible for the entirety of the game. To make sure that those building the game know what the result should be. The more a particular job function is concerned with the implementation (what language, coding patterns, what colors, how to light things) the less they are a Game Designer, but the more they affect the actual game's final design.
Character Design
Depending on the studio the specifics can vary. But modern character design ranges from character concepts to the implementation details, models, animations, voice, etc.
The importance of character design is how the character serves the game. In Team Fortress 2 for example, the character design is cartoonish, but the characters really sell the individual classes.  Being responsible for explicitly deciding key details of the character is the role of a character designer.
The game designer may say, we want a female character that in the beginning of the game is scared, lost, and injured, but slowly gets more confident. Then you build Lara Croft from the latest Tomb Raider.  The parts in between can be part of Character Design.  If it's a large studio, they may have animators and models, other artists, and your job is to provide them concepts, sketches, and to work with them to build the final product.
Comment: `A simple example of how a programmer decides to implement random affecting the game design.` Except that it's not. The choice of which algorithm to use to pick the next piece is a *design* choice, which was made by the game's designer. That is, a programmer did not arbitrarily decide, "hey, I'm going to change how Tetris picks the next piece." A game designer looked at what a pure RNG provided, didn't like it, came up with a solution, then told the programmer to implement it.
Comment: @NicolBolas hopefully they did.  And how often do bugs in games become part of the final product? It needed to be a simple example, but there are thousands of decisions made by programmers in every project that can affect the final game.
Comment: But they are not designed; they're *accidental*. To put it a different way, construction workers don't become architects simply because their work can affect the architect's design.
Comment: Right that's the point I was trying to get across. A game designer is thinking about the whole and end result, but a programmer or artist can make decisions that affect it. But that to be a game designer is coordinating all of it for a final overall product. This is exactly why there is a confusion as to what Game Designers do, because the implementation decisions affect the design.
Answer: When you're talking about a titled role, what you're talking about is the answer to this question: If I have a problem with/concern about X, who do I talk to in order to get it fixed?
If you have a problem with how a character looks or whether something is visible, you talk to an artist. The artist may in turn direct you to a programmer if it's a rendering issue, but your first stop is the artist.
If the game crashes, you go directly to the lead programmer (or more likely submit a bug report which goes to the lead programmer). The lead programmer will then figure out where that bug came from and forward it off to the appropriate programmer who can fix it.
If you have a problem with how the game feels in some way, your first stop is a game designer. That person can then assess the problem and perhaps direct you to the AI designer (who may direct you to the AI programmer) or wherever. It may even require an art fix/modification. But ultimately, it's a game designer problem and the game designer is the one who comes up with the solution.
Game designers need to consult with others in order to solve game design problems. They need to be able to work with programmers to make the AI do what they need. They need to be able to work with scripters who put which challenges in which locations. They need to be able to work with artists so that the graphics don't get in the way of the gameplay and fulfill the overall vision.
A game's designer has the ultimate responsibility for how the gameplay is designed and behaves. This can include elements of art, sound, programming, scripting, etc. But this does not mean that artists, sound people, programmers and scripters are game designers.
Just like the guy mixing concrete at a construction site is not an architect.


American vs European Options on equity index options

Question: I have a question regarding the usage of European vs American Options. According to Professional Risk Mgr Handbook 2010, American-style options are used mostly on equities whereas European-style options are used on equity index options like Eurostoxx 50. Why is this the case?
Answer: It is an attempt to make a general statement that is not entirely correct, and  certainly will become increasingly incorrect as new products are introduced. It is true that individual stock options traded in the US are American exercise. And the index options that are traded on the CBOE are European type, however there are also index options traded on the CME which are American. Also, I am not familiar with the situation in other countries, but it is unlikely that this pattern fits everywhere.
So it is just a generalization valid for the US in 2010 but with some exceptions (the CME options) even in that case.
The reasons are historical (choices that were made by option exchanges long ago) rather than anything substantial.
Comment: From my knowledge there are American Index Options, but only very small percentage and like 99% of Index Options are European.
Answer: You asked genuine question.
Remember one thing always, volatility is considered good by derivative players but not by the market as whole. More volatile is market, more riskier it is.
Since American option can be exercised at any time, whereas European options can only be exercised at the maturity only, so American options leads to excess volatility that would be otherwise either without the options or American options.
Regulator always aim to keep the volatility within a specific bound, since excess volatility would discourage investor for investing into the market, so they prefer European style option for both i.e. for index and individual stock. But American type is the first preference of speculator always. What is chosen at the end, believe me, depend on the bargaining power of both group i.e. regulator and speculator.
Since Index is the broad indicator of market performance it is the first thing seen by the investor before investing into the market. So regulators keep Index option as European and while Individual stock options as American.
Some countries might have American style option for both but now can understand why it is so.


Who wrote the Sephardi hoshanot?

Question: Who wrote the Sephardi hoshanot? The name יוסף בר יצחק is all over the acrostics, but who was he?
Comment: It's quite possible we won't ever know who he was. Oftentimes, we don't know who wrote a _piyyut_, even a common one, and even if we do know his name, sometimes we know little about him beyond that.
Answer: See here about the history of the hosha'anot(in hebrew), specifically the section about Sephardic tradition:
 https://he.wikipedia.org/wiki/%D7%A4%D7%99%D7%95%D7%98%D7%99_%D7%94%D7%95%D7%A9%D7%A2%D7%A0%D7%95%D7%AA
And here about R' Yosef bar Yitzchak(also in hebrew): https://he.wikipedia.org/wiki/%D7%99%D7%95%D7%A1%D7%A3_%D7%90%D7%91%D7%9F_%D7%90%D7%91%D7%99%D7%AA%D7%95%D7%A8
They originated over the years in Israel, Spain, Italy, and Yemen by different Chachamim and poets including R' Elazar hakalir, R' Sa'adia Gaon, and R' Yosef bar R' Yitzchak.

Who wrote the Sephardi hoshanot?


Unmodifiable music file tags

Question: I have some music files (.mp3 and .flac) which have unmodifiable tags: After I change the tags, they revert to their original values automatically. It's not related to access permissions (using Linux) as in a same directory, with the same permissions, some files have modifiable tags and other not.
Is there such a thing as "protected" or "unmodifiable" tags? Are there solutions to force modification ?
Thanks.
Answer: Check whether those files have several sets of tags (ID3v1, ID3v2, APE...) maybe you're editing ID3v1/ID3v2 and leaving APE tags intact, which might be the ones being read by your player.
Comment: Thanks, that was the problem. I tried using another tag editor (easytag), and I succeeded in changing the tags on rhythmbox.
Answer: AFAIK, there's no such thing as an 'unmodifiable tag' (unless the file is set to 'read only'), however, this situation sometimes arises when a tag is corrupted and/or written in a slightly non-standard manner that another application doesn't recognize.
In general when this happens, you can try using another tagging app, or more universally, use an application to remove the tag entirely, and then recreate it.
e.g. in MediaMonkey, Tools > Advanced Tag Management > Clean ID3 tags

Unmodifiable music file tags


Synchronous vs. asynchronous for publish subscribe communication between JavaScript objects

Question: I implemented the publish subscribe pattern in a JavaScript module to be used by entirely client-side oriented JavaScript objects. This module has nothing to do with client-server communications in any way, shape or form.
My question is whether it's better for the publish method in such a module to be synchronous or asynchronous, and why.
As a very simplified example let's say I'm building a custom UI for an HTML5 video player widget:
One of my modules is the "video" module that contains the VIDEO element and handles the various features and events associated with that element. This would probably have a namespace something like "widgets.player.video."
Another is the "controls" module that has the various buttons - play, pause, volume, scrub, fullscreen, etc. This might have a namespace along the lines of "widgets.player.controls."
These two modules are children of a parent "player" module ("widgets.player" ??), and as such would have no inherent knowledge of each other when instantiated as children of the "player" object.
The "controls" elements would obviously need to be able to effect some changes on the video (click "Play" and the video should play), and vice versa (video's "timeUpdate" event fires and the visual display of the current time in the controls should update).
I could tightly couple these modules and pass references to each other, but I'd rather take a more loosely coupled approach by setting up a pubsub type module that both can subscribe to and publish from.
SO (thanks for bearing with me) in this kind of a scenario is there an advantage one way or another for synchronous publication versus asynchronous publication? I've seen some solutions posted online that allow for either/or with a boolean flag whereas others automatically do it asynchronously. I haven't personally seen an implementation that just automatically goes with synchronous publication... is this because there's no advantage to it?
I know that I can accomplish this with features provided by jQuery, but it seems that there may be too much overhead involved here. The publish subscribe pattern can be implemented with relatively lightweight code designed specifically for this particular purpose so I'd rather go with that then a more general purpose eventing system like jQuery's (which I'll use for more general eventing needs :-).
Comment: [Duplicate](http://stackoverflow.com/questions/9526762/is-emitting-events-synchronously-incorrect). Also note you can implement pubsub in [250 bytes](https://github.com/Raynos/eventemitter-light), don't use jQuery for this, ever.
Answer: I always try to go with Async just for the fact that it stops the ui from locking up and allows you to continue to do "other" stuff on the page. You can always display some kind of spinner somewhere so that the user is aware that the element is waiting for something to come back.
If you go with sync then the system just locks until the request is returned. Normally this is a bad thing.


What is the gross weight limit for a Light Sport Aircraft?

Question: In the US, I see a lot of LSAs stating their take-off or gross weight limit as 1320lbs.  Can some of these planes have a higher physical limit and that 1320lbs is just more a category limit?
Answer: Yes, 1320 pounds is the regulatory Gross Takeoff Weight for Light Sport aircraft.
From the AOPA website:

Light sport aircraft are defined as simple, low-performance, low-energy aircraft that are limited to-
1,320 pounds maximum takeoff weight for aircraft not intended for operation on water; or
1,430 pounds maximum takeoff weight for aircraft intended for operation on water.
Answer: 1320 pounds is the weight limit for land-based LSAs, or 1430 pounds for sea planes. The regulatory definition is in 14 CFR 1.1:

Light-sport aircraft means an aircraft, other than a helicopter or
  powered-lift that, since its original certification, has continued to
  meet the following:
(1) A maximum takeoff weight of not more than—
(i) 1,320 pounds (600 kilograms) for aircraft not intended for
  operation on water; or
(ii) 1,430 pounds (650 kilograms) for an aircraft intended for
  operation on water.


Can I make my spaghetti sauce with puree instead of sauce?

Question: I have been making the same spaghetti sauce for about 50 years now.  It calls for 2 small cans tomato sauce, 1 can tomato paste and 1 large can of whole peeled tomatoes.  For the first time in all these years I purchased tomato puree instead of tomato sauce.  How can I adjust my recipe to use the puree or should I just bite the bullet and purcahse the sauce.  I'm not sure what I'd ever use the puree for.
Answer: I've been making sauce for even longer :-) and I think you'll be fine. If you, like me, always taste after all the ingredients are in, even before it has simmered, you'll know what you have to adjust. My proportions are generally one 28-ounce can pomodori pelati (Italian plum tomatoes), one 14.5-ounce can sauce or puree, and one 6-ounce can of tomato paste. If you find the puree thicker than the amount of canned sauce that you usually include, you can use slightly less or thin with a bit with water, but I don't think it will be necessary.


Baofeng UV-82 and DM-860 drivers Windows 7

Question: Currently I'm trying to make my radios (Baofeng UV-82 and Baofeng DM-860) friends with my Windows 7 and Chirp. My computer has only USB ports and no COM; Google adviced the Profilic driver (PL2303/PL23**) could help, but still no progress. Baofeng UV-82 LCD keeps blinking (blue and orange), being connected to the computer (and would not stop until the cable is put off), and no PnP sound is heard as well; Baofeng DM-860 (or DM-1801 - these two are just different names of the one model, as I can judge), surprisingly works (with their official app), but only allows reading from the radio, and the app crashes on trying to write to it. What can I do to get the stuff working? I have never had any drivers issues before, the USB ports all work properly for 'simple' devices (like mice, keyboards, flash drives).
Comment: Have you gotten anywhere with the problem?
Comment: @rclocher3, not at all, but I guess the cable is not what it should be... Will see in a couple days, thanks)
Answer: You don't mention what programming cable that you're using.  The programming cable has a very important job: it interacts with the OS as a USB device, and acts as a "virtual serial port", which means that the radio talks to the chip in the cable using a serial communications protocol.
The problem is that many inexpensive programming cables contain a USB-to-serial chip that's a close copy (a clone really) of a chip made by Prolific, so much so that Windows identifies them as Prolific chips. Windows Update will try to download the latest Prolific driver for the clone chips. Unfortunately for unsuspecting owners, Prolific responded to the flood of cloned chips by changing their driver to only work with genuine Prolific chips, so if you have the latest driver, a programming cable based on a cloned chip won't work. There is a work-around described here, which involves disabling automatic hardware driver updates, uninstalling any driver that's already installed, and then manually installing an old driver version.
But before you do anything drastic with drivers, go to the Windows Device Manager, by pressing the Windows key on your keyboard and then typing "device manager" and hitting <Enter>.  All the devices that the OS can see in the computer or connected to it are listed there.  If you unplug your cable, that "device" in the list will disappear, and if you plug the cable back in, then the device will reappear in the Device Manager list.  Find the device that way, and see how the Device Manager describes it.  If it's an "unknown device", then Windows doesn't even know what it is.  If there's a problem with the driver then there is usually an exclamation point symbol next to the device, and right-clicking the device and then clicking "Properties" will usually give some explanation of the problem.  If the Device Manager thinks that the device is fine, but the Properties dialog mentions "Prolific" somewhere, then you might have one of the programming cables with the clone chip.
Of course, you could be doing something wrong in the software.  I've successfully used the Baofeng software in the past, but I much prefer CHIRP, because it's well thought out and it works for just about any radio that can be programmed with a computer.  So you might want to try CHIRP, which has a mailing list with people who can help with problems.  There is documentation; here's the Beginners' Guide.
Comment: I can confirm that a counterfeit cable won't work with Chirp. The genuine cable I purchased later from Baofeng solved my problem. This was with Linux.
Comment: I got someone else's counterfeit cable to work once on Windows by following the painful work-around.  I've also had USB-to-serial cables that couldn't be made to work on any OS---in other words, they were complete garbage.


google scholar citation for github repository

Question: I am preparing the code for a paper which already published (without my name on it). The code is about to release now and I was hoping to add that to my google scholar or something to keep a record of the citation. Should I put the papar in my google scholar and somehow mention I worked on the code?
Comment: Welcome to academia SE. Could you clarify your question? Specifically the part 'Should I put the papar in my google scholar and somehow mention I worked on the code?'
Answer: No, your name is not on the paper so you should not include it on a list of your publications. You can, of course, list it as an achievement/project/experience on your CV/Website/ORCID/whatever.
If you think your name should have been on the paper and you were not consulted prior to submission, you can inform the journal. This will be a quick way to make enemies of your not-quite-co-authors, however.
You can make your code "citable" (scare quotes because "citable" is being used to mean creating a version of record and a DOI for it, rather than merely being allowed to cite it). There are various repositories which will allow you to get a DOI for non-publication work, here are some examples:

GitHub/Zenodo - integrates directly with GitHub
Figshare - not just for figures, despite the name
Mendeley data - owned by Elsevier, so perhaps can have reasonable confidence in its staying power

Another option is the MethodsX journal, although you'd have to check that your work is suitable for the journal and not going to constitute double-publication. As this is a peer-reviewed journal, it gives you a higher level of "credit" than the other options above. Note, there is a mandatory open-access charge with this journal. (Or, even, if your code is distinct enough from the paper, you could look at publishing a full paper of your own in an appropriate journal; there are lots of software/code papers, even in non-CS fields.)
As you wish for the code to appear on your Google Scholar profile, you will probably need to choose MethodsX (or another Journal) as Google Scholar only indexes article-type documents. You could manually add the others to your publication list as an "other" type publication, but you won't the full suite of scholar features (citation monitoring etc.) that way.
Finally, unless the code is entirely your own work, any of the above will require communication with, consent from and credit to your collaborators (presumably those who published the paper you weren't on).
Comment: Regarding "if your name *should* have been on the paper": if it was a considered decision to exclude OP from the author list, I agree that protesting would create ill will and probably accomplish nothing. If it was an oversight, it *may* still be possible to correct the author list with the approval of the co-authors and editor. I've seen author lists modified shortly after publication to correct mistakes.
Comment: True, although I don't think most journals (officially) allow this. In such a case, OP would want to go through the corresponding author, and not direct to the journal.


Unanswered questions and accept rate

Question: People have been asking me to increase my accept rate on Stack Overflow. So I've gone back to my questions and have been trying to select the best answers. But for some questions, I have not received any ideal answers. What should I do about those questions? Leaving them open will cause problems with my accept rate, right? I'm feeling like I shouldn't have asked some of my questions in the first place. If I delete them, would it affect my reputation?
Comment: [This answer is in .. unacceptable condition .. unacceptable!](http://www.youtube.com/watch?v=toA9Ffaj9MQ)
Comment: possible duplicate of [Should I accept wrong answers to boost my accept rate?](http://meta.stackexchange.com/questions/134069/should-i-accept-wrong-answers-to-boost-my-accept-rate)
Comment: Related: http://meta.stackexchange.com/questions/63087/whats-an-answer-in-stack-overflow-culture
Comment: Agreed! About half of my questions receive answers that don't help.  I can't accept an answer, when it doesn't answer my question.  I feel that the accept rate can be detrimental, as it will deter point snobs from submitting an answer, through fear they won't get that extra set of points.  I say BAH.  I frequent SO sites almost every day, but have never broken the 1,000 point mark.  It doesn't mean my questions or answers are any less valid.  It DOES mean my questions are largely unique, attracting few views.
Comment: @MikeChristian: `point snobs..` real professional. Comments like that deter answers more often than an accept rate.
Comment: Ok, how about "users who are more concerned with increasing their commu
Comment: @François: My point is that basing contributions on points is UNprofessional. You know it happens. Why are you upset that I mention it? In my opinion, describing such users as "point snobs" is accurate. Is there another term you prefer? (Double post- sorry! My phone data connection dropped out before I could finish.)
Answer: Don't feel that you need to accept an answer on every question.  Jeff Atwood considers an accept rate of 70% or more "quite good".
Comment: +1 for the "quite good" link
Comment: But just because Jeff considers 70% good, does not mean everyone else does. When people constantly pass by your question because they think it has a C grade, this 70% can be detrimental.
Comment: @Jono: Why would they think your question has a C grade?  You, as the asking user, control your accept rate.  If the choices are you only having a 70% accept rate or you accepting bad answers, you're better off with the 70% accept rate.  Accepting bad answers *may* come back to haunt you later on.
Comment: I have no intent of accepting bad answers, which is why my rate is in the 60's. And people often tell me my rate is too low, or will not answer my questions because of it. Which is why I think the accept rate concept needs to be improved.
Comment: Who is Jeff Atwood???   :p
Comment: @atconway No, that would be... your mother! What did you expect? (OK, quoting Spy lines from TF2 is getting old now)
Answer: IMO questions without a single answer should be ignored for the accept rate. A very skilled person might ask questions which are very difficult to answer (because this person doesn't have to ask simple questions), so after a few questions without answers, his accept rate might be close to 0%. Admitted, bad answers might skew the accept rate anyway.
Answer: I would see the problem from another point of view: if you ask something, you have a problem. If you don't get any helpful answers after some days, describe what you have done to circumvent that problem and accept that answer.
This shows anyone who finds himself to have the same problem a possible solution.
It is even possible to put a question and to answer at the same time, so this way is perfectly valid, as soon as your answer is really the only helpful one. Copying and only marginally improving a given answer and accepting yours (and not the other one) would be impolite, however.
Comment: Self-answering is **encouraged** and we thank anyone who takes the time to come back and tell us what the solution is when we don't otherwise know.
Comment: @DonalFellows Thx, just improved my answer.
Answer: You are going to have to work on the answer yourself. Take the best info from each answer and give credit to each answerer. Then do a lot of Googling and research to come up with more info or resources and add it to the answer. List some different approaches and pros/cons of each one.
It's not ideal but at least when someone has the same question in the future, they will benefit from all your work.

Unanswered questions and accept rate


Speaker Enclosure Material

Question: Im building a (Portable) speaker. I have a design and most of the electronics done already, but i need some help with the enclosure. I'm not sure what to build it out of, since I've heard some conflicting Info. Some say MDF is the holy grail top quality speaker enclosure material, while others say it is the worst possible material. I want a decent sound to come out of this thing, so I also need dividing walls inside as there are more that one speaker in the box. What material should I use?
Comment: Mdf is toneless.  I love my Adam!  Which are made out of mdf,  my wooden b&w lack so much compared to the adams. But its a wrong comparison after all..
Comment: Use MDF, it is good.
Answer: MDF has very good acoustic properties at a low price.  But it is heavy and does not hold up well to being bumped around.  Also doesn't do well in moist environments.  It is not used for pro portable speakers for those reasons.  It's a good choice for speakers that won't be moved very much.
Almost all professional speakers use void free Baltic Birch plywood.  Baltic because, in theory at least, the most dense and consistent birch comes from Russian trees.  But there are a lot of different grades of Baltic Birch out there.  What you will generally get in a consumer store (home center etc) is sold in 4' x 8' sheets like regular pine plywood and is not really what the pro's use.. it may have voids (gaps within the inner layers).  The good stuff is usually sold in 5' x 5' sheets.  Check with a specialty wood supplier in your area.
If you are looking for something a little less expensive, Arauco Pine plywood is often used by amateur speaker builders.
In all cases, the speaker builder is looking for a material that is very stiff, dense and consistent.. with minimum resonance.. that is to say, when it does vibrate, it does not favor any particular frequency.  The speaker cabinet should (as well as possible) be a perfect container which does not respond to the pressure of the sound waves within it.
MDF, being made of very small wood fibers that are mixed with resin (glue) and hardened under pressure, is very dense and consistent.  There are no components within it large enough to resonate on their own.
Plywood is made from sheets of wood which are glued together flat.  Because each layer is still a piece of natural wood, there will be some knots and other variations in the wood.  The manufacturer of the wood has to choose the best (most consistent, with the least defects) wood to put in each sheet of plywood.  They will also sometimes cut out defects and place another piece in that spot to fill in any gaps.
Since trees are not always cooperative in providing perfect wood, the manufacturer will sort the wood out and sell it as different grades, at different prices.  For some jobs, low grade plywood with large numbers of inconsistencies will be fine.  For other jobs it may not be.  For example, for furniture building where the grain of the wood is visible, a builder would not accept wood which has any visible (filled-in or otherwise) defects visible on the outer layers.
In the case of speaker building, when plywood is used, plywood made from hard (dense) wood with a consistent grain, which is stiffer and has few resonances is desired.  That is why void free Baltic Birch is preferred.
The Arauco pine I mentioned is used as a second choice because although pine is not as dense as baltic birch, this particular pine plywood is said to have less resonance than other plywoods, at lower price than high grade baltic birch.
Comment: Nice info!  Could you add some acoustical properties of the 3
Comment: Thank for the info! The main reason I want to use MDF is because I want to decorate it and the technique I want to use works quite well on MDF. Also the weight isn't too much trouble as I worked out that it shouldn't weigh more than 5kg when done(using 16mm thick walls), which I can carry for what I want to do. Also couldn't the MDF be sealed to protect it a bit?
Comment: Yes, and there are lower cost commercial speakers which are not built from plywood, for example I owned some Electrovoice Eliminator speakers that were made with OSB (Oriented Strand Board) which is glued-together chips of wood.. similar to MDF which is more like compressed and glued sawdust.  It's not totally wrong to use these materials for portable speakers, it's just not as sturdy as the Baltic Birch.  For a personal project where you'll be taking care of them, any of these materials would work reasonably well.
Comment: @frcake ok I have added that, to the best of my knowledge.  If a person wants to know real details as to the acoustics of speaker cabinets, it is really beyond the scope of this answer and they would need to read some books and serious articles specifically on that subject.
Comment: @little_birdie , that seems logical. I haven't got the time to dive into speakers yet.. I'm a bit stuck on tape machines :D ill read it all when i have a bit of time! thanks in advance for the information!

Speaker Enclosure Material


Theoretically, is the analysis of the moves more complex if the objective is to be the first to be checkmated?

Question: I have seen variations of other board games or strategy games where the aim is to actually 'lose' the game by forcing your opponents to make moves. Applying this concept to the rules of chess, would it require a completely different set of skills and thinking to let your opponent checkmate you first? Is the variation of moves and the analysis of the moves different if the winning objective or condition is reversed?
Comment: The point from the answer of @Sid below is right; playing by the standard rules of chess, neither opponent would be able to compel the other to checkmate. (E.g. `1.Nf3 Nf6 2.Ng1 Ng8` etc.) The question would make more sense if asked about how the skills used in standard chess relate to those needed for success in [losing chess](http://en.wikipedia.org/wiki/Losing_chess), which among other rule changes features compulsory capturing.
Comment: The headline asks about more or less skills. The detailed question asks a different question, about whether skills are different. Please clarify.
Comment: @Laska thanks for pointing this out. I have made the update to the question accordingly :)
Answer: Although selfmate is a popular type of chess problems, the concept you have described simply would not work in a chess game played from the starting position; your opponent would need to cooperate with you if you want to get yourself mated. This means that any game played by chess players of any skill level would almost certainly end in a draw under your rules, which unfortunately makes your question moot.
Answer: This is actually interesting, as there is a certain counter-intuitive way to win. If you end up with a huge material advantage, in some positions you can force your opponent to checkmate you.
Comment: A common ending in such a backwards game may be forcing your opponent to checkmate you with one of their pawns.  You could try to block one of their pawns until the very end when the pawn then becomes the only piece your opponent can move.
Answer: It would be a different kind of game.  You'd still want to build up a material advantage to be able to force your opponent to checkmate you.  But you would almost always need more material than that which is required to checkmate your opponent.
It would also be more difficult to win material by threatening your opponent's king since your opponent would only need to defend when a move to get out of check is required.  Similarly you would need to worry about getting your king out of check but not about being checkmated.
More positions would likely be drawn than in standard chess so you could say the analysis is simpler in this sense.  Then again finding a win when one exists would be more difficult for a random position than in standard chess so the analysis is more complex in this sense.
Answer: I write this as an answer (even if it doesn't contribute that much, but it would get too long).
If you ask any expert of the selfmate genre in problem chess, he will give you an immediate enthusiastic yes: Selfmate strategy is much more complex than n#. Here is an especially glaring example: Motive inversion. In "normal" chess, you will never make a move that hurts yourself, with only one exception: if you play for stalemate. In selfmate, you might play moves with positive and with negative aspects, even with both at the same time, and to top it, White might use the exactly same motive that Black used to parry a selfmate threat (say, unpinning a piece of his to harmlessly interpose a check), and use it for his own good (whoops, now the unpinned piece must mate). I googled a random example - try understanding the strategies of both sides without getting a knot in your brain!
That said, in a practical game, you probably don't need such fine details. Follow the advice of ericw31415 and user11382: win all the material of your opponent, except a safely blocked pawn. Then force your own mate by zugzwang. The minimum material needed is KQB/KP. If your opponent still has major force, say a Q, the "standard" strategy in long s# is "checking the opponent into place" until you can give the decisive check that immediately forces selfmate.
Comment: Great answer, helps visualize how one might actually do it. So once you accrue a material advantage, is the idea to check the opp King and force pawn moves while placing your King in a position where the pawn can deliver smothered mate? Can you provide an example starting from e.g. KQB (or more material if it helps) vs KP, against an opponent who will try to avoid mating you? (If this seems a lot of work for an extension, I could open a new question for it)
Comment: Also the humility about lack of contributing with this answer is misplaced - the top-voted and accepted answer seems to have shallow consideration and in this case like it could be outright wrong. (One assumes that it is possible to accrue a large material advantage against an unwilling but substantially weaker opponent. We need only prove that with this advantage we can force a selfmate.)
Comment: @MobeusZoom: The Schwalbe Problem Database https://pdb.dieschwalbe.de/?langw=DE can be searched for such problems. (G='s#' finds only selfmates, and the number of pieces can be fixed too.) I'm too lazy at the moment, my bath waits :-)


Do we edit self promotion or leave it to be down voted?

Question: I was checking the edit queue and found a suggested edit to remove a link to the answers own blog. It wasn't declared, and looking at the profile it is obvious it belongs to him, however it appears that the answer might contain decent information to the question. Should we accept/edit these links out, or downvote them and flag them for self promotion? This answer in question is here: https://serverfault.com/a/496819/60820
Answer: It depends. Overt self promotion is frowned upon and generally treated as spam. Is one link in (what appears to be) an otherwise valuable answer overt self promotion? I don't think so.
The links in the answer aren't provided because the answer is a précis and the linked documents add additional information, they are there because credit goes to...
The question now becomes Should an OP need to give give credit to themselves?
For me the answer to that question is no. They already have credit for the answer because their name is on it and it's linked to their profile.
For me it's a valid edit. The answer appears valuable so shouldn't be downvoted/flagged for self promotional reasons. If the OP reverts the edit or posts more in a similar style then it's probably a good idea to bring it to the attention of the mod team so we can review their activity and take appropriate action.
Comment: Seems a bit overboard to call that one "overt self promotion". The link was quite relevant to the post and added additional information.  I believe it was wrong of the community to edit out the second link. It's like we're on a witch hunt for someone who *might* be self-promoting instead of looking at the content and asking if it's relevant to the post.  In my experience, spammers usually don't put time into writing good quality, relevant answers.  Maybe it would have been better to edit it and say "see X for more information". That way the question of credit isn't even an issue.
Comment: @jmort253: I quite clearly say that _I_ don't think it is overt self promotion.
Comment: I see that hiding in there now. :)  But, still, the answer was edited to remove the link. I feel like that should be used for cases where someone demonstrates a pattern of abuse or wrote a really low quality answer and then slaps their link in the post. I don't know this user too well and haven't investigated myself, but I wanted to bring this up because I believe it's important to tell the difference between people trying to promote themselves and people who legitimately want to help others and just happen to have relevant content they've posted elsewhere that they want to add as a reference.
Comment: @jmort253: Personally I just try to accept that what people say is what they mean and not read too much into it. He's giving credit to himself, it's not required.


How do I change the background layer default color to white?

Question: I was following a tutorial when I somehow changed the background layer to black. Whenever I open Photoshop, the background layer is automatically black instead of white. How do I change it back to white, the original one?
Comment: I'm voting to close this question as off-topic because this is about Photoshop use in a non-photographic context.
Answer: Press the "D" key.  This will reset to the default background color of white, and foreground color of black. You can also press "X" to switch them back and forth.
After you have done that, a new layer will be the color of the current background color which you have reset to white.  If you close Photoshop and reopen, it should retain that setting.
Answer: Change the background color to white as shown in the reference image.
Answer: If you mean the colour of the background of newly created images that setting is in the new dialogue called Background Contents where you can tell photoshop to create the new image with a specific background whether that be black, white or transparent.  Your question was a little vague as to which background you're talking about.  But I'm under the impression that you're talking about new images.  If not, could you expand on your question? ^_^


How do I launch my new, free service leveraging WebApps without running afoul of the current community?

Question: So far, in the Trello launch, we've had some bumps in the road with directing users to webapps to ask questions. This is definitely my fault for not spending enough time familiarizing myself with the way the community operates before directing users to it. So, to hopefully make up for some of the pain that's happened with the Trello launch, I think it'd be a good thing to have a community wiki that tells other people thinking of launching with references to webapps what steps they should take.
Answer: The general policy here is that you can recommend us as a venue for getting answers but only alongside a list of OTHER resources too.

e.g. "for trello support, try the following public places: place a, place b, stack exchange, place c"

Per
Is it okay to use Stack Overflow as the support forum for a product or project?

One way is as you saw with Subsonic -- where they simply provide a single link to Stack Overflow among other links of places people can go to discuss Subsonic.

Listing us as the FIRST point of contact, even above your own Trello meta, is definitely a mistake. the ordering is off there -- we should not be at the top of the help page. For example:

Trello's own meta at the top
then {other public resource X}
then {webapps stack exchange}
then Twitter, depends how much they want to promote that, it seems like a different thing
Answer: Here's what I would've done differently.

Spend some time clicking around and familiarizing yourself with the editorial guidelines and the way the site operates. Do this well in advance of launch.
Ask a question on meta.webapps, giving a link to your proposed referral page (help page) and asking about refining language.
Let the traffic build naturally. Don't "Astroturf" by asking questions about your product.
Identify yourself as a member of the team on every answer or question, by adding a comment to your own post that you are a member of the team.
In referring people to Web Applications, get a jump on making it clear what kind of questions are appropriate, and make sure you're describing to people the site they're going to. There's good text on the About page for you to use.


How are whole Haplotypes for Sequencing isolated?

Question: Is it possible to reliably isolate and amplify DNA from individual sperm and/or eggs (from a fish)? I'd imagine that the small amount of DNA would make the PCR a bit wacky. We've considered irradiating sperm and attempting to create haploid females via gynogenesis, but I was wondering if there was a faster and easier method that could utilize gametes directly.
Comment: Are you limited to a particular species of fish? Or can you use one of the asexually-reproducing species?
Answer: If your aim is to isolate the two haplotypes (chromosomes) maybe you should try flow cytometry. You might read this paper http://www.ncbi.nlm.nih.gov/pubmed/21181533 by Dolezel which is leader in the field, at least for plant chromosomes. I'm pretty sure that the applicability of the method depends on the physical properties of the chromosomes you have (especially their size distribution).


Keeping used/dirty clothes in suitcase

Question: While travelling with one bag/suitcase. What is the best way to keep dirty/used clothes in bag along clothes with clean/new clothes.
Answer: I always bring a large kitchen trash bag in my suitcase when I travel. At the end of each day, I put my dirty clothes in the trash bag (and close it, if it has a drawstring). When I re-pack my suitcase to go home at the end of the trip, I put any clean clothes in the bottom of the suitcase, then put the closed trash bag full of dirty clothes on top of it. The plastic trash bag keeps the clean clothes from getting dirty, and it also helps me unpack quickly at home:  I just take the bag out and empty it right into my laundry hamper.
Answer: Get a suitcase with a zip cover on each side. The clothes get put in the dirty side once you've worn them. They stay separate (unless you forget to zip one side up before you close it of course).
Answer: I use separate (ziplock) bags, for smelly/dirty clothing, for used but can be used again and for small items of clothing that tend to get lost between the bigger items.
When you do your laundry while traveling you fold the bags and store them till you get the same level of dirt again.
Instead of ziplock bags you can also use the thin nylon shopping bags or wash bags which are quite easy to get these days.
A slightly longer version on Travel Stack Exchange and the other answers to the same question might help you as well, even though the question is not a duplicate.
Comment: Yeah, I only throw the dirty clothes inside plain nylon shopping bags then stash them in the same bag/suitcase with everything else. Works well, as long as the nylon bags are not torn of course.
Answer: Use a cloth bag so the clothes can breathe. If you use a plastic bag they'll be a bit icky after a few days. If you have one with handles or a drawstring you can hang it up tidily. Those cloth shopping bags are good for this.
If you don't have a cloth bag handy use a pillow case, or a used T-shirt.
Comment: If you put your real dirty dirties in a bag where they can breathe, they will get the rest of your clothes dirty.
Comment: Goodness! I never got them that dirty on holiday.
Answer: Nylon bags are really good point for humid climate. I used plastic bags in Thailand and got actual mould on my dirty laundry. Then switched to nylon bags and solved this. Also, many hotels have free nylon laundry bags.
Plastic trash bags work well in dry climate.

Keeping used/dirty clothes in suitcase


How do you barbeque a whole piece of fish?

Question: I tried having a visbraai this weekend and was a little bit dissapointed by the result. The skin of the fish sticked to the grill and the flesh stuck and crumbled on the grill. I suspect the weber was too hot. Any advice on barbequing a whole-piece of fish so that it does not crumble and the skin does stick on the grill?
Comment: related : https://cooking.stackexchange.com/q/87/67  ; and if you want to try wrapping it, see https://cooking.stackexchange.com/q/24919/67
Answer: I BBQ whole fish or fish filets with or without skin quite regularly. You suspect the BBQ was too hot, but usually BBQs are not hot enough (unless you were REALLY hot and over like 800F?). Make sure grill is clean and apply oil to the grill and to the fish. Put fish skin side down on the BBQ until crispy and flip fish until cook to your desired temp. It might stick a bit, but it should not stick so much that it causes problems.
Common problems might be:

Sticky grill because it is dirty and not oiled
Grill is not hot enough
Fish is flipped too soon and did not get a chance to cook enough to separate itself from the grill
Fish is flipped more than once
Fish surface is not oiled (I suggest also oiling the flesh side)
Using a thick spatula (thin metal is better)
Pushing spatula hard to get under the fish. You don't need to do this. Just slide the spatula slowly under the fish if you find it is a bit sticky and more progressively.
A dirty BBQ or applying to much oil could perhaps cause a flare up. You can usually listen for the flames and if you hear fire or see it then use a spray bottle with water to disrupt the flame.
Comment: @NeilMeyer don't drench it... put oil on a paper towel and wipe down the grill. Pour oil on your fish and then rub it around with your hand, pick it up and let the excess run off, and then put it onto a hot grill.
Comment: Ok oil to the fish and grill, are you not going to make flames if you add oil to the fish / grill?
Answer: Grill on slices of lime, lemon, and onion.  Can also use tin foil. Can oil the grill and fish.
Answer: EASY :)
You scale and gut it and wrap in 2 layers of aluminum foil with chopped tomato and onion in the cavity and juice of small lemon all over so that it steams in those juices. DELICIOUS!
Important Tip: Make sure no lemon seeds get in as they will severely reduce the deliciousness factor.
Experience will give you the cooking times, it varies by size but while a small 10 inch long bream might only needs 3-5 mins on one side and 2-3 on the other on a medium-hot BBQ plate, even a big fat 20 inch fish will only need 7-12 min on one side and 5-7min on the other to be done.
Experiment by starting with small fish and find a set routine for double wrapping that it can be easily repeatable.
You will soon figure out how to keep the juices in and how to keep the opening on only one side so it's easy to open.
It doesn't even need to really be turned for small fish once you learn to get the wrapping right and will find that a medium heat nicely enclosed will cook nicely via steam.
If you want to go gourmet add any combination of seasoning, think chili cumin garlic dill basil pepper etc but in all honesty if it is cooked the right amount it's delicious with just onion tomato and some lemon and freshly caught ocean fish is an experience all on it's own just like this!
Scale this idea up at home in the oven by wrapping your bigger fish in and extra layer or two of foil (depending on your oven heat, more if it's hotter) and placing in a shallow baking tray surrounded by your favorite roasting veggies but focus on the fish don't over cook to accommodate the veges, 20-30 min max for med to large 30 to 40 inch long fish in hot domestic kitchen oven.


Downloading photos and video clips from my Panasonic Lumix TZ10

Question: With my  old camera a Sony cybershot I was able to download photos and video clips using the Wizard. but when I use this with the Lumix it only downloads photos not the video clips.  I have used the Photo fun software to get round this but now means I have photos etc. in other places, but would prefer all my photos and videos to be in the folder where I have all my Sony stuff. Any ideas please ?
Answer: Use the built-in windows file explorer instead of those nasty wizards. Just press WinKey + E and it will open explorer (or right-click Start and click 'Explore'). Your device will be displayed like an additional drive. Look in the folders on the drive (displayed like 'Sony Cybershot) and you will find your photo's and video's there. From thereon, you can just copy and paste those image and video files like any other files on your pc.
Comment: Note that I'm reposting an answer that someone had deleted, it seems right to me


Non-coordinate basis in GR

Question: I am reading Nakahara's Geometry, topology and physics and I am a bit confused about the non-coordinate basis (section 7.8). Given a coordinate basis at a point on the manifold $\frac{\partial}{\partial x^\mu}$ we can pick a linear combination of this in order to obtain a new basis $\hat{e}_\alpha=e_\alpha^\mu\frac{\partial}{\partial x^\mu}$ such that the new basis is orthonormal with respect to the metric defined on the manifold i.e. $g(\hat{e}_\alpha,\hat{e}_\beta)=e_\alpha^\mu e_\beta^\nu g_{\mu\nu}=\delta_{\alpha \beta}$ (or $=\eta_{\alpha \beta}$). I am a bit confused about the way we perform this linear transformation of the basis. Is it done globally? This would mean that at each point we turned the metric into the a diagonal metric, which would imply that the manifold is flat, which shouldn't be possible as the change in coordinates shouldn't affect the geometry of the system (i.e. the curvature should stay the same). So does this mean that we perform the transformation such that the metric becomes the flat metric just at one point, while at the others will also change, but without becoming flat (and thus preserving the geometry of the manifold)? Then Nakahara introduces local frame rotations, which are rotations of these new basis at each point, which further confuses me to why would you do that, once you already obtained the flat metric at a given point. So what is the point of these new transformations as long as we perform the first kind in the first place? Sorry for the long post I am just confused.
Comment: You're so used to working with *coordinate* bases that when you see the metric $\delta_{\alpha \beta}$, your brain screams 'flat space!' at you. But this is not so. The Christoffel symbols in an arbitrary basis contain terms proportional to the derivatives of the metric, which you're familiar with, *as well as terms proportional to the commutators of the basis vectors*, which vanish for coordinate bases. Hence, even if we write $g_{\alpha \beta} = \delta_{\alpha \beta}$ everywhere in some patch, we can still find a non-zero Riemann tensor if our basis vectors don't commute.
Answer: This transformation is done locally, i.e. so that $g_{\alpha\beta} = \eta_{\alpha\beta}$ in a neighbourhood rather than a single point. I believe that due to topological effects, we cannot in general do it globally. However, even though the new basis is orthonormal, we have to remember that it is (in general) non-holonomic, i.e that there is no set of functions $y^\alpha$ satisfying
$$
e^\mu_\alpha = \frac{\partial x^\mu}{\partial y^\alpha}.
$$
This means that the curvature does not (in general) vanish. Indeed, it holds that
$$T_{\alpha\beta\ldots\gamma} = e^\mu_\alpha e^\nu_\beta e^\sigma_\gamma T_{\mu\nu\ldots\sigma},$$
for all tensors $T_{\mu\nu\ldots\sigma}$, as is obvious by the linearity of $e^\mu_\alpha$, and thus in particular for $R_{\mu\nu\sigma\tau}$. You may be confused if you have learned that the connection coefficients are given by
$$
\Gamma_{\mu\nu\sigma} = \frac{1}{2}\left(g_{\mu\nu,\sigma} + g_{\mu\sigma,\nu} -
 g_{\nu\sigma,\mu}\right),
$$
but this is only valid in a holonomic frame. More generally
$$
\Gamma_{\alpha\beta\gamma} = \frac{1}{2}\left(g_{\alpha\beta|\gamma} + g_{\alpha\gamma|\beta} - g_{\beta\gamma|\alpha} + C_{\gamma\alpha\beta} + C_{\beta\alpha\gamma} - C_{\alpha\beta\gamma}\right),
$$
where $f_{|\alpha} \equiv e_\alpha(f)$, $[e_\alpha,e_\beta] = C^\gamma{}_{\alpha\beta}e_{\gamma}$, and $C_{\gamma\alpha\beta} \equiv g_{\gamma\delta}C^\delta{}_{\alpha\beta}$. In particular, in an orthonormal frame:
$$
\Gamma_{\alpha\beta\gamma} = \frac{1}{2}\left(C_{\gamma\alpha\beta} + C_{\beta\alpha\gamma} - C_{\alpha\beta\gamma}\right).
$$
Unless I misunderstand you, the rotations you refer to are local Lorentz transformations, and we are interested in them because each orthonormal frame corresponds to the instantaneous rest frame of an observer (with velocity field equal to $e_0$), and thus these rotations transform between different rest frames.
Answer: Note that the Transformation you mentioned
$g_{\mu \nu} \mapsto g(\hat{e_\alpha},\hat{e_\beta})$
by the function $e_\alpha^{\mu}$ (also called the tetrad) is only a Change of coordinates if it holds:
$e_\alpha^{\mu} = \frac{\partial u^\mu}{\partial x^\alpha}$.
Here, $u^\mu(x)$ is a vector function and you can choose this function such that at some Point $x_0$ you have a flat metric. If you have done a suitable choice of $u^\mu$, metric tensors in a neighborhood of $x_0$ will not be flat in General. The Transformation
$g_{\mu \nu} \mapsto g(\hat{e_\alpha},\hat{e_\beta}):=\frac{\partial u^\mu}{\partial x^\alpha}\frac{\partial u^\nu}{\partial x^\beta}g_{\mu \nu} (*)$
will preserve all geometric Tensors like curvature Tensor, Torsion Tensor, etc. up to a Change of coordinate Basis. More precisely, if $X_{\mu_1 \mu_2 \dots \mu_n}$ is a geometric Tensor like the Riemann Tensor, it will Change under the Transformation (*) as
$X_{\mu_1 \mu_2 \dots \mu_n} \mapsto \frac{\partial u^{\mu_1}}{\partial x^{\nu_1}} \frac{\partial u^{\mu_2}}{\partial x^{\nu_2}} \dots \frac{\partial u^{\mu_n}}{\partial x^{\nu_n}}X_{\mu_1 \mu_2 \dots \mu_n}=X'_{\nu_1 \dots \nu_n}$
like a Tensor should transform. Another Transformation that does not Change geometric quantities are local rotations $\Lambda^{\mu}_{\nu}(x)$. In this case you have $e^{\mu}_{\nu} = \Lambda^{\mu}_{\nu}$. Such rotation matrices have the property that its inverse matrices is simply the transpose of it (from which it follows that $det(\Lambda) = \pm 1$). A geometric Tensor will transform similary:
$X_{\mu_1 \mu_2 \dots \mu_n} \mapsto \Lambda^{\mu_1}_{\nu_1} \dots \Lambda^{\mu_n}_{ \nu_n} X_{\mu_1 \mu_2 \dots \mu_n}=X''_{\nu_1 \dots \nu_n}$
Other forms of the Tensors $e_\alpha^\mu$ (not coordinate transformations or rotations) change the intrinsic geometry!
Comment: I see, so the first kind of transformation mentioned in the book, transforms the metric into the flat metric just for a given point, not over the whole manifold, but the transformation applied at that point is applied to all the other point, right? And for your last statement, why would one make a transformation that changes the geometry of the manifold? Doing this you lose all the information you have about your space.
Comment: @Silviu It is not true that more general linear transformations change the intrinsic geometry. Additionally, the transformations referred to in the book are almost guarantueed to be intended as to make $g_{\alpha\beta} = \eta_{\alpha\beta}$ locally (in a neighbourhood, not in a point).

Non-coordinate basis in GR


How to measure elevation above sea level

Question: Elevation is often measured in terms of "[unit of length] above sea level." Considering that the oceans aren't a uniform height, how is this measured?
Comment: Related: http://earthscience.stackexchange.com/questions/6694/why-do-we-measure-eustatic-sea-level-from-the-center-of-earth
Comment: Related (if not a duplicate?): http://earthscience.stackexchange.com/questions/2214/what-is-the-appropriate-vertical-datum-to-use-globally
Comment: Measuring the air pressure is in theory, at least a simple and effective way of measuring altitude.
Answer: It's actually an inordinately difficult problem. Neither the land nor the sea level is stable. A tide gauge along a coast needs 30 to 40 years of data to filter out the very noisy tidal and other weather signals. By the time one has homed in upon a precise average, one is already within the time-frame of land uplift or subsidence, and that is before we even think about the complexities of climate-change generated sea level rise, or quasi-decadal oceanic oscillations. Then there is the question of Earth's non-homogeneous gravity which affects local sea levels. For example if we correctly measure the elevation of a Himalayan peak relative to average sea level at the Gurarat coast, west India, we get an elevation of 'h1'. We can then measure the same peak relative to sea level in the Ganges delta, east India, which we will call 'h2'. We can make all the usual corrections for Earth's curvature etc., yet h1 will be different to h2 - though both are 'correct'.
There is no stable bench mark on 'God's Earth', so maybe the answer is to get off the planet completely. Satellite orbits are not perfect, but they are predictable, so satellite-based measurements of elevation are the best available.
Comment: I still don't understand. How then do they measure elevation if there could be multiple answers that are all correct? (That last point about the Himalayas was actually what I was thinking of when I posed the question. Well, it was actually the Rockies, but the point remains the same.)
Answer: This question is more about surveying than earth science.
Every country with an ocean coastline determines it's own standard for where sea level is. A mean point between the lowest tide mark and highest tide mark is generally taken to be the average sea level.
A surveying datum station is place at that point and all elevations above sea level, for those countries are referenced back to the national standard datum.
Comment: Where to site a national datum is arbitrary, decided on pragmatic reasons of ease of access, ease of construction, and shelter from waves.
Comment: @DonielFilreis the various national geologic survey groups (e.g. USGS) agree on a common datum to call "mean sea level" and put down standards to measure this from.  See http://www.ngs.noaa.gov/datums/vertical/ for examples.  In a nutshell, its arbitrary and it doesn't really matter how it relates to where the water actually is as long as everyone is measuring from a common accepted reference datum.
Comment: This still doesn't really help anything. Take a look at Gordon's answer and my reply. How do they determine where to place "sea level" when there could be numerous sea levels, especially in countries with multiple oceans bordering them?


How many numbers less than $x$ are co-prime to $x$

Question: Is there a fast way , or a direct function to give the count of numbers less than $x$ and co-prime to $x$ .
for example if $x$ = 3 ; then $n = 2$ and if $x$ = 8 ; then $n = 4$.
Comment: [Euler's totient function](http://en.wikipedia.org/wiki/Euler's_totient_function)
Answer: The relevant function is the Euler Totient function and the link contains several ways to compute it.
Answer: Yes there is. First of all, you have to prime factorize your $x$, any put it in exponential form.  Suppose you have the number $x = 50$. The prime factorization is $5^2 * 2^1$.  Now take each number seperately. Take the bases and subtract 1 from all of them. $5-1=4$. $2-1=1$. Now evaluate the each base/exponent combination after subtracting the exponent by 1. $5^{2-1}=5$. $2^{1-1}=1$. Now multiply your answers. $(4)(1)(5)(1) = 20$.
If you want to try out your examples, $3=3^1$. So your answer would be $(3-1)(3^{1-1}) = (2)(1) = 2.$ For your other example, $8=2^3. n=(2-1)(2^{3-1})=(1)(4)=4$.
I guess in general, prime factorize your $x$ to $a_1^{b_1}*a_2^{b_2}* ... * a_n^{b_n}$ and your answer will be $((a_1-1)(a_1^{b_1-1}))*((a_2-1)(a_2^{b_2-1}))*...*(a_n-1)(a_n^{b_n-1})$
Answer: You can also use the inclusion-exclusion principle.
Example: $1001=7\cdot 11\cdot 13$ has three distinct prime factors, 7, 11, and 13.
among numbers from 1 to 1001, there are $143=11\cdot 13$ multiples of 7, $91=7\cdot 13$ multiples of 11, $77=7\cdot 11$ multiples of 13, 13 multiples of 77, 11 multiples of 91, 7 multiples of 143, and 1 multiple of 1001. Therefore $\phi(1001)=1001-(143+91+77)+(13+11+7)-1=720$
Answer: Here is a cool proof that I learnt on how to compute the Euler Totient Function  $\varphi$ that uses probability theory. On one hand, $\varphi(x)/x$ is the probability that a number selected between $1$ and $x$ is coprime to $x$ while we can alternatively compute the probability as follows:
A number between $1$ and $x$ is coprime to $x$ iff it is coprime to each of its prime factors. Given a prime factor $p$ of $x$, the probability that a number selected between $1$ and $p$ is coprime to $p$ is
$$\frac{p-1}{p}.$$
Since the events of selecting when a number is coprime to each prime factor are independent, we can multiply the probabilities together to get the total probability being $\prod_{p|x} (p-1)/p$. Equating this with the result before gives you the pretty formula
$$\varphi(x) = x\prod_{p|x} \frac{p-1}{p}.$$


entity Reference with select list doesn't show results

Question: i'v created a content type with a entity reference field - select list.
in the field settings i'v choose the desired content types for the select list. the preview select list was populated with all the wanted data.
when i create a new content of the above content type the select list of the entity reference is not populated. the only option i have is -none-.
any suggestions?
Answer: Ok, the problem was due to the fact that the site has two languages. had to enable the second language in order to make the it work properly.


Why does my Fujifilm FinePix S1800 have far greater shutter lag in EVF mode than in LCD mode?

Question: The shutter lag on my Fujifilm FinePix S1800 is much longer in EVF mode (just under half a second) than in LCD mode (about 0.15 seconds).  What would explain this anomaly?
Comment: I would guess a firmware bug since, as far as I know, the LCD and EVF are getting their data in the same way. The only real difference is a minor one in the resolution which, I suppose, could cause one to have more processing over the other and so make the camera a little less responsive. However, since this is all guess, I just posted a comment.
Comment: Are you sure you've controlled for all variables? That sounds like the sort of difference you'd expect between all of the auto focus / exposure running and not.
Answer: As has been addressed in a comment to your question, it could do with the amount of memory the camera has, and how much processing it needs to do. If all other parameters are equal (settings, subject, exposure), then I have no idea. The EVF has less pixels than the LCD, so it should process quicker, which isn't your case.
The only other thing I can suggest, is asking whether you're encounter actual shutter lag, or just EVF refresh rate lag?


How can I do multiplayer using Minecraft on iPad?

Question: I play Minecraft P.E. on my iPad Air, and I have a friend who does as well. My other friends say if you are near each other while playing, it will work. For me it clearly doesn't. I was wondering if you could help with this problem. So, is multiplayer possible on the iPad Minecraft P.E.
Comment: Are you connected to WiFi?
Answer: Local Area Network
When on the same network, you and your friend can easily join each other's worlds. First, the host must load up a world. Then your friend taps on Play, and there should be an extra world with your username, highlighted in purple.
Multiplayer for Minecraft PE
You may buy an app for $2.99 that allows you to host and join servers with only your device. With the app, you can join PocketMine servers and servers created by other users. Voice chat is one of the features in this app that makes it great. However, there is a player limit of 4 on regular servers. Using this app to join PocketMine servers is better because it lists some great servers available to you.
PockeMine-MP
You can also host a server on a computer and then join on your device. Tap edit and then external. Enter your public IP and keep the port default if you do not know what to do. Make sure you know how to port forward, or this will not work. Remember that you have to manually add servers. You can find great servers on the Minecraft Forums.
Hope these solutions helped!
Answer: If you go into Options, there should be a button marked 'Local Server Multiplayer'. The host must have this option on in order for you to join.
Answer: First your friend has to join their world.
Second press play and once you do you will see a world with a highlighted in purple.
Finally press it and will be in your friends world.
Comment: Also you could buy a multiplayer app, but your friend have to have it too. First go to the app and press multiplayer.Second Once it is done loading get off the app. Finally Press minecraft and you'll see a wold that has a purple name and press it.


How much influence do president-elects have before inauguration?

Question: In the US, assuming that a president-elect isn't a Vice President already, how much influence do they have before they get sworn in/inaugurated?
Comment: @CandiedOrange I'm trying to exclude scenarios like Bush senior going from VP to P and instead focus on scenarios like Hillary Clinton or Trump becoming president.
Answer: President-elects have very little influence on before they are sworn in. They can be influential in setting what future goals and directions their party will take in the coming years, but the day to day activities during the lame duck session aren't something they have much control over.
President-elects don't have a lot of time to try to influence anything the current government is doing, because the months spent between election and inauguration are spent planning the hundreds of appointments and staff hires needed to make a smooth transition.