What does 'swingy' mean?

Question: What does 'swingy' mean, in the context of tabletop roleplaying games?
Answer: Although I mostly agree with @Brian's answer of "Highly Variable," swingy isn't used just to indicate the standard deviation of a single die roll.
Yes, you can call a 1d20 more "swingy" than a 3d6 mechanic, but the term is also used on a larger scale, as in "swingy" combat is combat where overall results can be highly variable.  This can be from a number of different reasons and swinginess of individual mechanics isn't necessarily part of it.
For example, a system where you roll group initiative and PCs are not super durable. If everyone on one side gets to go before everyone on the other side, and there's no admonitions that "it really happens at the same time" (Alternity does this to mitigate the effect), you get a swingier system, because there is a huge benefit in going first - you can often eliminate the other side's heavy hitter/mage/priest/whatever is relevant a priori and then the rest of the combat is very one-sided. So even if the initiative roll itself isn't "swingy" mechanics wise, so much depends on it that the overall outcomes are swingy. So high standard deviation, but not just of single rolls but of total results.
It could also mean a game system that is good for swingers, like Theatrix Ironwood.
Comment: I'd just like to add a bit about when the swinginess is on an encounter level as in this example. Combats that are swingy are often referred to as "rocket tag". A useful bit of jargon, in my opinion.
Comment: The initiative example is one I've really noticed as someone who plays both D&D and Warhammer. In Warhammer, an entire army goes on the same initiative, and it absolutely makes fights more swingy than they'd be if we had a similar scale of fight in D&D. (Of course, a D&D fight of similar scale to a typical Warhammer fight would take forever!)
Answer: Highly Variable
I use the term to mean "highly variable." Specifically, I consider a 1d12 (avg 6.5) to be swingy whereas the roughly equivalent 2d6 (avg 7) are not swingy, because they follow a bell curve rather than an equal probability of falling to either extreme like the d12.
It has a subtext of "unreliable" because of its variable nature, though that's not true of all cases.
Answer: Swingy is in general used to define some form of number generation with a wide variance in outcomes. A good example would be damage done by weapons in D&D. In 3.5D&D a Greatsword does 2d6 while a Greataxe does 1d12, thus the axe is more swingy. The sword is overall more consistent in doing damage and as a bonus has a minimum of 2 damage instead of 1. A single die will be more swingy then numerous dice because the chance of being any of the outcomes is equal unlike with multiple dice which will tend to have a bell curve.
Answer: I have heard this in more than RPGs, and it generally means that something can either be really powerful or really weak.
Ex: Something that does 1d20 damage is more swingy than something that does 2d10 damage is more swingy than something that does 3d6 damage.
Ex: Something that can kill 1d10 enemies and will knock you unconscious.  Killing 10 enemies is really powerful, but killing 1 of 5 enemies and knocking you unconscious is really weak.
If you need more clarification, ask and I'll give more examples.

What does 'swingy' mean?


Avoiding legal issues with plot similarities between my book and a movie in production

Question: I am writing a novel whose plot that I just learned is going to be made into a movie---how can I protect myself if similar plot points are used so that I don't get sued and vice versa?
Comment: The plot, or the premise?

And by 'vice versa', do you mean how can you protect the film company from being sued by you? I would think you would just... not sue them.
Answer: "Similar plot points" is a little vague. Boy Meets Girl, Boy Loses Girl, Boy Gets Girl Back are "plot  points" which have been used since Gilgamesh was a teenager. (ETA and Boy Meets Boy as well, as Gilgamesh himself proved. And Girl Meets Girl.) The question is whether your specific setting, characters, time, and action are similar to the movie which hits the screen.
And even then, it's in the execution and the audience. The Twilight series is set in contemporary times, has a central female character in a love triangle, and features vampires and werewolves in the Northwest U.S. So does Patricia Briggs's Mercy Thompson series... and they could not be more different. Bella is a passive, chaste 17YO human who marries a sparkly vampire. Mercy is a tough, independent thirtysomething shapeshifting coyote who is the object of attention for two werewolves and is "friends" with a very deadly vampire.
Focus on writing your story. Make it the best it can be. When this movie comes out, go see it with a friend, and then ask the friend to read your story with an eye to potential overlap. There may be nothing to change. A lot can happen between script and screen, and between your fingers and your finished novel. I wouldn't sweat it now.
Comment: Actually if memory serves right, it's also *Boy Meets Boy* since Gilgamesh.
Comment: You are absolutely correct. In fact, I am going to update my answer to reflect that.
Answer: If your intent is to have the novel published (not self-published) and your story is too close to the movie - I'd guess you won't find a publisher. Problem solved.
Your novel must "stand on its own merits" and if it does then there is a chance that even with a similar plot it might sell but if your novel is not as good/exciting/professional as the movie it will be compared/contrasted with the movie by every agent and editor and there is nothing you can do about that.
Last time I check- plots are not something that can be copyrighted.


Will the latest versions of Firefox be brought into old Ubuntu releases?

Question: Will updated versions of Firefox land in old Ubuntu releases, such as Lucid and Maverick, when they are released by Mozilla?
Answer: Yes, while a release of Ubuntu continues to be supported, it will receive the updated versions of Firefox.
Note that most Ubuntu releases are supported for 18 months after release. For example 10.10 is over 18 months old, and will not receive security updates, such as new versions of Firefox. There are some Ubuntu releases that are LTS (Long Term Support) releases which will continue to be supported for three or five years.
The graph below (from Wikipedia) shows the support for various releases. Yellow is the standard 18 months. Orange is the extended support on the Desktop. (Red is extended support on the Server only, this does not include Firefox.)
Answer: New Firefox versions will become your default browser if Firefox is your default browser, and you install the updates available for your system.
The browser that comes with 11.04 is FireFox 4.0 and while it is the default it is not the latest version. You can update it if you like, and as long as you didn't change the default from firefox, you will have the latest FireFox as your default after the update. But this is not exactly automatic by any stretch.


Are already privately bound books a deterent for publishing houses?

Question: I've read somewhere that putting your story, or a piece of it, on the internet would make it difficult (not to say impossible in some cases) to find a publisher wanting to publish your script. Would I encounter such difficulties if say I let my story be bound in a book as a present to somebody (so only one exemplar), and decided later I wanted this story to be published?
Answer: Having a copy bound, either from a Do-it-yourself kit or through a place like Kinkos doesn't pose any problems. The problem with putting a book on the internet or by using a self-publisher or PoD publisher lies in the contract and the rights. By making a single copy and not actively distributing it or signing any contract, you haven't used any publication rights. When you sign on with a self-publisher or PoD publisher you sign a legal contract (even if it's just by pressing that you accept their ToS) and you effectively use up your first publication rights.
Also, you're allowed to post an excerpt of your story on your webpage. As long as it's not a significant portion of the story, you're okay. "A significant portion" does vary by publisher and there is no set "rule" for how much that is, but as long as you stay under 50% you shouldn't have any problems.
Comment: Uhm... "there", not "their".  It slips into my writing from time to time too, that's how insidious those mistakes are; I blame, at least in part, reading this mistake (oh, and the other close cousins of it) so often one the intarweb.
Comment: Whoops dang typos. This is what happens when you type faster than you think. =P
Answer: I will defer to some of the editorial folks, who may know better, but I believe you'd be okay.  If you head on down to the local Kinkos and get your work bound nicely, nobody will ever know.  The main issue with rights is if a work has been made "publicly" available.  On a webpage, anyone with a computer can see it.  A single copy in the hands of a single person isn't a big deal.
Self-publishing and POD packages, however, often include getting an ISBN for your work, and that will probably raise some flags.


Sum of log p/p for p equivalent to l mod D

Question: It's fairly classical that for $D>1$ and $(D,l)=1$ one has
$$\sum_{\stackrel{p\leq x}{p\equiv l\; (mod \; D)}}\frac{\log p}{p} = \frac{\log x}{\phi(D)} + \textrm{O}(1)$$
where if I understand correctly the dependence on $D$ in the $\textrm{O(1)}$ is captured by something like
$$\frac{1}{\phi(D)}\sum_{\textrm{non-principal} \; \chi}\frac{-L'(1,\chi)}{L(1,\chi)}$$
which is $\ll_{\epsilon}D^{\epsilon}$ for any $\epsilon>0$.  If this is correct, suppose I am interested in the sum
$$\sum_{\stackrel{p\leq x}{\left(\frac{-D}{p}\right)=1}}\frac{\log p}{p}$$
where $\left(\frac{-D}{p}\right)$ is the Legendre symbol.  There are $\phi(D)/2$ residue classes mod $D$ that $p$ can lie in, and so then this is just my previous sum $\phi(D)/2$ times, and I get that it's $1/2 \log x +\textrm{O}(1)$, where the dependence on $D$ in $\textrm{O}(1)$ is now something like $\textrm{O}(D^{1+\epsilon})$.  Is this the best one can do?  I was hoping I could get it to be $\textrm{O}(D^{\epsilon})$ but if that's not even correct perhaps I should stop trying.
Comment: Just out of curiosity. Does the $O(1)$ term converge to some constant? Could you refer me to some literature on this question? : )
Answer: You're right that your proposed method for estimating the new sum, while correct, gives a worse error bound than we can obtain otherwise. Rather than quoting the classical result itself, I suggest going back to the proof of that classical result and modifying it to address the new sum.
Somewhat more precisely: the Legendre symbol $\big( \frac{-D}p \big)$, or rather its multiplicative generalization the Jacobi symbol $\big( \frac{-D}n \big)$, is a Dirichlet character (mod $D$)—call it $\chi_1(n)$. The sum you are interested in is just
$$
\sum_{p\le x} \frac{\log p}p \bigg( \frac{1+\chi_1(p)}2 \bigg).
$$
(Not exactly, since this expression counts primes dividing $D$ with weight $1/2$, but that's easily dealt with.) Therefore you're left with needing to understand $\sum_{p\le x} (\log p)/p$ (no problem) and $\sum_{p\le x} (\chi_1(p)\log p)/p$. The latter sum is going to be $O(1)$ in the same way that the error term in the classical problem is $O(1)$; it is going to be related to $-L'(1,\chi_1)/L(1,\chi_1)$. So in fact you don't have all the different $-L'(1,\chi)/L(1,\chi)$ error terms to deal with, only the single one where $\chi=\chi_1$.
Comment: Thanks, now that I see that it seems obvious.  I had tried to work it out that way (since it did seem unnecessary to go through all of the characters to get information basically just about one) but for some reason I was failing.
Answer: That's a good question, as it illustrates that one should try to find the "correct" harmonic analysis for a given problem (of this type...). What you can do is represent the characteristic function of your set of interest (the $p$ where  $(-D/p)=1$) as a combination of Dirichlet characters;  by quadratic reciprocity, you only need the principal character and a real character. So you can get your error term as the sum of two error terms coming from
$$\sum_{p\leq x}{\chi(p)\log(p)/p}=\delta(\chi)\log(x)+(Error).$$
This should give what you want.


Starting vehicle on hot days

Question: Why it is easy to start the vehicle on hot day than on cold days?
Since on winter days it is diffcult to start than on hot days I thought it is due to the low temperature which in turn affects the chemical reaction in the cell.Since energy is produced in the cell due to reaction.But I don't think it is the correct one..
Answer: There are two main reasons
As temperature is decreased the voltage of a car battery decreases and it's internal resistance increases. This means the battery can supply less current.
As temperature is decreased the viscosity of oil in the engine increases so the engine is harder to turn over.
In the days before fuel injection there was a third factor because carburettors are less good at vaporising fuel at low temperatures, but this won't be a problem for most modern cars.
Comment: The viscosity of the fuel could slow down the injector rates, unless the design specifically compensates for that.
Answer: Well in winter day's the cylinder's in which combustion takes place and the fuel as well as surrounding air are at very low temperature so when you start the engine the cold fuel and air mixture enters the cold combustion chamber and at that time the temperature of the spark produced by the spark plug for a very little instance of time is not sufficient to rise the temperature of the fuel gas mixture to the level at which it can burn and start the engine. Well after sometime you see that engine just start's and shut's down. I think this is because when the fuel burn and start expanding the heat is instantly absorbed by the cylinder walls and it stop's the expansion of the gas due to which piston is not able to move and engine don't start.

Starting vehicle on hot days


Is Google Page Speed Service a competitor for CDN services

Question: I've been googling around for a cheap CDN service and came across: http://code.google.com/speed/pss/index.html
This seems to be a competitor to other CDN services, is this the case?
Thanks
Answer: Ok, judging from the faq it proxies pages and images (up to 50M) and follows up visits (how many? all of them? wasting bandwidth?) and POST requests (up to 2M) to the original site.
It does not serve videos or swfs, and I suppose zip files too are out of question.
It proxies requests, but it modifies your webpages (to improve speed, yeah) this part of the service could break some scripts.
It sounds good, as long as it stays free, but it's hard they keep it so after testing is over.
For a small fee, the amazon competition still looks in good shape.
The best thing about it, to me, is the fact the setup may happen during worst case/slashdot scenarios, when you have no access to the overloaded server, but the DNS panel of your registrar may still be functional.
The worst thing is that it's not clear if in such scenario your server would be actually freed of the pression and clear to operate or just clogged back again in by the google proxy. I suppose it woud be freed, but the details on that are quite important and not clear. (as the service is not officially focused on availability)
It may be a google way to shovel the google apps network of servers back in niches where it cannot go because of their choice of python as a programming language, but that's just a hunch I have.
Answer: Yeah I have recently come across a few free ones. The best that I have seen are:
http://www.incapsula.com/
https://www.cloudflare.com/
They have some security and other benefits also. Worth checking out.
For some more information on what there is available out there it is also worth checking out http://cloudharmony.com. They do benchmarks and give out information on the major competitors.
But from what I understand, for large commercial websites it's still better to use a CDN. These kind of speed up services are still a but buggy. Some of the speed up services also integrate a spam protection which can be buggy sometimes and block people.
Note that the bug CDN's as amazon etc are not that expensive, only a few cents per gig.


96 Legacy Overheating

Question: I have a 1996 Legacy that is overheating. After looking over the car, it only overheats under load after driving for about 5 min after it warms up. It happened before and i noticed the coolant had a brownish hue to it and the catch tank was dirty as all hell. After flushing the system and replacing the cap and thermostat it started overheating again a month or so later. Now it coolant is very brown and the catch tank is filthy again. the car only overheats under load. I also have a check engine light that comes on every so often. It will be on for a week, then turn off for a few days, then turn back on again. And when i got the light checked i got an P0440 code. If it helps any, it has the 2.5L motor in it.
Answer: The brownish color of the coolant means that oil and coolant circuits mix. This is most probably a symptom of a leaking head gasket. If this is the case you should have it repaired asap, as it typically affects not only heating but also lubrication, and this can seriously damage the engine over time.
Comment: Definitively agree with this.  Head gaskets.
Answer: Simply overheating would not contaminate the coolant. As answered above, it could be contaminated with engine oil, or even transmission fluid if the radiator has an integrated transmission heat exchanger.
You could also have combustion gases leaking into a coolant passage, either through a crack or a failed head gasket. I'd suggest a compression test to see if you have a cylinder low. Alternately, there are combustion leak test kits. Google that term to find them, and they are about $50.

96 Legacy Overheating


Running - should it be done when you're hungry?

Question: What is the recommended time for running, in respect to meal time and hungriness (amount of sugar on your blood)? If the answer depends on the goal of the exercise, please explain for weight-loss.
Comment: How much of a head start does the food truck you're chasing have?
Answer: In general, I don't think that whether you're hungry or not is relevant at all.
Just because you're hungry doesn't mean that you don't have sufficient glycogen stores for a run.  If you are hungry, the hunger will probably subside once you start running as exercise causes you to have an increase in insulin.  Any increase in insulin is followed by a low, at which point you'll feel the hunger return.  This may be after you're run, or if you're exercising for a longer period, it could be before your workout is over.
Cardio for weight loss is often suggested to be done first thing in the morning on an empty stomach, that way you will start burning stored glycogen immediately, and if you're eating a low carb diet, possibly go directly to burning fat for energy.  Again, whether you're hungry or not is still irrelevant.
If you just ate, you will burn sugar in the bloodstream first when you run.  Depending on your metabolism, and how long since your last meal, you might not even digest that last meal yet because blood will be pulled to the extremities during your run, and away from the stomach in order to supply oxygen to the muscles working during exercise.
Comment: why empty stomach, then?
Comment: The empty stomach would be so your body will use up your glycogen and start converting fat for energy rather than trying to digest whatever is in your stomach.
Comment: You will go right to burning glycogen, or if you are eating low carbs, you will go right to burning fat.
Comment: why does exercise increase insulin levels? Isn't that usually a bad thing for weight loss?
Answer: I usually run after work, but before dinner. I definitely notice that I have less energy than when I haven't had an afternoon snack. I have often run when I was feeling hungry, but rarely feel light-headed after running. I'm usually hungrier after running. I think I do my best when I run about 1.5 hours after eating. That's long enough to not be nauseous, but have a good amount of energy from the meal. I find that my schedule and the weather control when I run more than anything else.
Answer: The 'burning more fat on an empty stomach' thing is mostly bullshit. Weight change is pretty much determined by the difference between your calorie intake and calories spent. Whether you're hungry doesn't factor into how effective an exercise is at burning calories.
I always try to eat something an hour or two before working out, to avoid dizziness and nausea from my blood sugar dropping too low.
As for weight loss, you're better off working on that in the kitchen. To get in shape, I'd shoot for weight lifting instead of just running.
Answer: I often find that I'm hungry when I first wake up. However, a few minutes into my run I no longer feel hungry. I'm assuming the insulin increase is responsible for this.  I have also noticed that the mornings when I run (or do calisthenics) I stay "un-hungry" for up to a half-hour or even an hour after I work out.
I think (hope?) that this is because my body has turned to burning fat for fuel once my glycogen stores are used up, because there's nothing in my stomach for it to digest, but I don't have a source for this.


What's the recommended bitrate for Background Music in iPhone Games?

Question: What is the recommended bitrate for Background Music in iPhone Games?
Comment: Just to clear up confusion I had: BGM is background music.
Comment: I edited the question to clear it up even more.
Answer: In all honesty, it's probably down to what sounds best at the lowest bitrate.
So if you had music at 192kbps but you could still get it sounding decent without a whole lot of quality loss at, say, 64kbps, then you've got no reason not to use the 64kbps version.
It might be worth having a bunch of different bitrates of the same song and see which "sounds" the best, whilst reducing the bitrate. If you've got some 8-bit retro sounds in the music you could get away with fairly low bitrates, but probably less so with a piece of music with a wide variety of sounds and textures (e.g. a classical composition, with full percussion, and synths and basses on top).
Just as an extra, if you're not certain about what sounds correct at a low bitrate, I'd suggest talking to an audio producer or if that's not possible then just ask the guys at Audio-Video Production SE those guys definitely know their audio :)
Answer: Like Ray Dey said, you need to make the call on quality vs size. Remember the project triangle?
The same applies to audio. You can have good quality audio that doesn't take up a lot of space, but you'll have to manage streaming it and you're often limited to a set number of streaming channels on non-PC hardware. You can have good quality without streaming, but it will take up a lot of memory, etc.
Something to check out, if you are working with composers who would be comfortable writing the music in trackers, you can use FMOD (iPod/Pad/Phone and PSP license is listed under "Casual" on their Sales Page and is $500 flat) and load .MOD, .XM, and .IT. You can have high quality samples and fine-grain control over the flow of music.


Which gems are most useful in traps in Gemcraft (Chapter 0)?

Question: In Gemcraft Chapter 0, which of the 8 gem colors are the most useful in traps?  Are there some colors that are only worth it to put in towers?
Answer: Well, this depends on your playing style, but generally, any gem that has a long-lasting effect (i.e. Slowing and Poison) are better, because their Effect is enhanced.
Damage-causing gems become less effective, so Splash and Shock are not good choices for normal play.  They could be a good choice on a swarm level, however.
And finally, if you are using Stealing gems primarily as a source of income, you would, of course, benefit in placing them in traps, rather than towers.
Comment: I always use Green, the higher the better
Answer: This really depends on how far you are in the game. Some endgame tactics focus on getting a really high lvl triple gem in a trap.
Personally I'd try to start out with a high lvl poison/green gem where the creep start. This will kill the first couple of waves enabling me to quickly summon them with extra monsters where needed. Ramping up lots of mana early on.
Later on I usually try to add a slow/blue gem close to my towers to slow down the mobs passing by.
Orange mana gems are great if you start out the level with some traps. Just put in some and let the mana flow.
Answer: Red-Orange
The RO gem collects mana from not only it's alien passer-by, but also others around it, thanks to the red splash effect. It is also capable of wiping out weak aliens that pass by. Orange, and Red-Orange gems are used for "Manna Farming"
Green Gems
Green gems are a great choice in traps. You can place traps with green gems all around the track to create a "Poison Trail". Poison doesn't stack (a poisoned creature that goes over a green gem again doesn't do anything), so it's not beneficial to put them next to one another. Poison trails have a new green-gem trap on spaces where the last poison effect wore off, to make your monsters continuously poisoned, so they drop dead before they reach your base.
Light Blue Gems
Light blue gems shock a creature, giving it damadge and freezing it in place for a few seconds. Durring this time, it doesn't move, so it can be hit many times by your towers. It's a great idea to place these next to your towers.
Blue Gems
Blue gems have a simliar effect, only they slow the monsters down. Placing these near towers means the monsters slow down to take more hits by towers as they pass by.
Purple Gems
Purple gems lower the armor (defense) of monsters, making them take more damage.


What is a substitute for half-and-half cream?

Question: I need to know if there is a substitute for half-and-half (~10%) cream because I am baking a cake without it and I am allergic to it.
Comment: The best substitutes are also milk-based; are you allergic to all dairy products, to lactose, or specifically to cream?
Comment: If you can provide a recipe, we can better understand the purpose of the cream in your cake and perhaps offer more useful substitutions.
Answer: When I am substituting in a recipe, I usually use coconut cream instead of cream or half and half if called for in a recipe. (There is a question posted here that covers how to get the cream from a can of coconut milk.) Sometimes I use soy creamer, but sometimes that can be hard to find. I'm sure you could experiment with a mix of soy creamer and soy milk.
My ideal solution is to use vegan recipes to start with, because they are formulated without milk or eggs. Maybe in your case, just look up dairy free cake recipes, if you don't mind eating eggs. There are a lot of cookbooks and blogs out there with a ton of vegan cake and dessert recipes.
Answer: Half and half can be pretty closely approximated with one part whole milk and one part cream.
However, if you're allergic to half and half, I would infer that you're allergic to all dairy.  In that case, you may well need a specific dairy-free product like a soy-based cream or half and half or coconut milk.
Answer: You can also try coconut cream and milk in equal proportions.


How can I use Windows via Parallels or Fusion with MINIMAL HARD DISK space?

Question: I would like to use VMWare Fusion or Parallels (or another option for running Windows within OSX; not Wine), but I am concerned about the hard disk space requirements.  How can I reduce the hard disk usage when creating a new Windows WM?
Answer: Both Fusion and Parallels give you the option of creating dynamically sized virtual hard drives. They allow you to specify the maximum size of the virtual hard drive, but do not actually consume (or reserve) that much disk space on the real hard drive. So to answer your question, just be sure to create a dynamically sized virtual hard drive. (I believe this is the default in both Fusion and Parallels.)
Answer: When you make a new virtual machine, set the hard drive as dynamically expandable (rather than have it allocate the whole virtual hard drive size right away). From time to time you can also compress the virtual hard drive size. Also use a version that doesn't take too much space (e.g. Windows XP doesn't need as much space as Windows Vista). One important thing to consider too is that the more you install, and reinstall, and change, and add files (even if you delete them), the more space it uses. Even if you're VERY careful, you should have at least 10GB available for the virtual machine.
Of course, you also have the option of getting a relatively small external hard drive for not too much money just for the virtual machine if you're really concerned about the space. However, if you'll use the VM frequently, that may not be the best option (unless maybe you get a firewire or USB3 SSD).


Dwarven Militia won't do anything

Question: If I go to the Unit list, it lists my militias job as "Soldier (cannot follow order)". I can't see any reason they wouldn't be able to follow the order (namely to kills some goblins). Any idea why they might be just standing there like idiots and not doing anything? I'm at a loss.
Answer: "Cannot follow order" usually means some sort of perceived pathing problem. Are any drawbridges lowered/extended? Did your soldier get walled in by a careless mason? Are the goblins in an unreachable place? (Such as dodging into a pit or pond).
If nothing else, sometimes it helps to toggle/retoggle your militia, to see if that can't fix it. Ultimately, move orders tend to be easier than carrying out attack orders -- try stationing them near the goblins in question?
Answer: This happened to me when I accidentally put all my military dwarves in the safety burrow, they refused to leave to go eat / drink / kill. Is your military associated with a burrow?

Dwarven Militia won't do anything


Which raid instance has the most gear that I need?

Question: I use Rawr and maxdps to figure out which drops I can benefit from but it's a very tedious and manual process. Sometimes I join a raid without knowing whether I'm likely to get any drops that I need. Are there any tools which can help answer the question which raid instance I should focus on to improve my gear?
Answer: There's also Kaliban's Loot Lists that detail drop recommendations by instance/boss and class. You can (manually/mentally) compare against your character and figure out which bosses you particularly need.
Besides that, you can run character auditors like http://be.imba.hu/ and http://wow-heroes.com/. I like WoW Heroes for the character comparison option and Be Imba! for the raw auditing and instance suitability chart.
Answer: Trying using the AtlasLoot addon. It allows you to filter by instance/raid and there's an option to only show items that your character can use (class filter). You can also supplement this with the WoW Heroes website to see your gear score and find upgrades for items, sockets and enchants.
Answer: Wowhead has a great feature for searching for upgrades.  You can plug in the lowest and highest item level you'd like, what classes it is for, and any other filters.
They also have a Stat Weighting section which helps you find upgrades by taking a SWAG at the right stats for your class/roll.  You can also look for crafted-only items, specify which kind of gems you're using for the sorting, all kinds of stuff.
Here are some examples:

Paladin (holy) weapon upgrades beyond 251.
Druid (bear) wrist upgrades beyond 251.
Death Knight (frost DPS) upgrades beyond 200.

Ninja Edit:
It also shows you where items drop, right below the name of the item.  <Boss> - <Zone> <Raid Type>.
Answer: I know this question is old, but I'll answer with some current(Cataclysm 4.0.6) info incase anyone else finds this and is curious.
I use guildox.com and maxdps.com, filtered for the content my guild currently does.  Once you plug in your realm and name you can see what gear you have and how much of an upgade everything is.
You then have to manually keep track of what drops where, or just use atlasloot and manually add everything to your wishlist.
At this point in the game(4.0.6), don't expect too many upgrades. I've gotten 0 loot so far, and only need 2 or 3 items per zone on normal.  Rep rewards, Valor gear, and BoE craftables are really good now.
Answer: Nope. I believe that Rawr will let you filter gear by instance though. So filter everything except the instance you are going to. Shouldn't be too time consuming.
Answer: If you find your character on armory ( http://www.wowarmory.com/ ), there is a 'Find an upgrade' button next to each of your gear item. That should tell you where you can find better items to what you currently have and which bosses drop them.
Answer: For raid instances at this point, 99% of your gear will come from the highest tier of raiding (currently ICC / Ruby Sanctum) or from badge gear. I would check Wowhead for Ruby Sanctum drops, and concentrate on that, ICC, and heroics for badge gear.
Answer: You could use a website like AskMrRobot which loads your character details from the WoW armory and then calculates upgrade paths, item reforges, gemming, and enchanting for you.


How to prevent commercial use of a photo?

Question: I got a request from a guy who'd like to use this image of mine for a print. I am normally open to non-commercial (simple attribution is okay) usage of my photos. So, I wrote "Drop me a flickr mail or contact at my email if you'd like to get the full image for a non-commercial print". However, I am concerned that some people might misuse this and use it for commercial purposes. So, How do I go about ensuring non-commercial use of a photo? Do I take any signed document from the person or simple email acknowledgement of non-commercial use will suffice?
Answer: I would have a simple agreement that is electronically signed stating the permission and use for your photo. That way both parties are covered and there is no later issue of "he said - she said." It was clearly stated in writing.
A service like this is available for electronic signing.
Here are a couple sites that may help you along with the agreement. I do not know these sites or how accurate their content so use with caution.
Commercial Contracts
Defining Commercial Use
Legal Documents that a Photographer Needs
Also with different countries coming into play that might make things a bit sticker but it still should work okay as most countries adhere to contract/copyright law.
Comment: Thank you, can you please provide a link to a similar agreement document?
Comment: @ShutterBug - updated answer to list a few sites that may help. I did not find a complete example but those should give you a start.
Answer: If you say that the picture is for non-commercial use only then it's for non-commercial use only.
If you have a signed page stating this than the other person can't say he didn't know the picture is for non-commercial use only.
But, if that person is a jerk and uses the photo for commercial purposes anyway, what are you going to do? based on your comment you are from Bangladesh and the person is from Chile but is in Australia — can you afford a law firm that will handle this international lawsuit for you?
So, you can't "ensure" non-commercial use, but most people are somewhat honest and if you tell that person clearly that the picture is for non-commercial use and that this is important to you most likely everything will turn out okay (and it not then don't let it discourage you from doing this again with someone else, dishonest people do exist but they are a minority).
Answer: Just a little pointer from Europe.
In Europe a verbal contract has the same value as any written contract. I would assume this is similar in most of the world. The reason people prefer a signed contract is because these are difficult to fight and you don't end up in a "I said" or "I didn't say" debate.
Further, I've seen the suggestion to send an offending party a bill several times, on the idea that you just charge them a fee - or alternatively they have to stop using the image etc.
Now how viable that is in your case I really don't know. Personally, I would say that the moment you have any form of written agreement, you are in a legally binding contract - and if that says non-comemrcial use it says non-commercial use - period.
Now assuming your "customer" would break the contract, you can send a lawyer after him, or report it to the police, etc. but the question that may be asked is what economic damage was done to you. If you never sell any images and someone sells a print at a high price, it may be hard to prove that you have financially lost out for example - as a result image infringements also often won't go beyond a "cease and desist" order from a court, simply because it isn't worth fighting over it. There are exceptions to this - primarily press and tabloid related, but these relate to images that sell for several thousands a piece.
I suspect if you wanted to have an extra deterrent you could possibly include any "damages" in the contract, however you should consult a lawyer over this because I'm not sure if you can.
So what can I conclude - it is really a matter of trust and people respecting contracts. Nothing else.
Finally, if you are willing to pay a step yearly fee, you can possibly try this against web use:
http://www.digimarc.com/digimarc-for-images
(Note: I don't, photography is expensive enough for me already, but then I normally don't print anything nor do I get requests for copies of my images.)
Edit: It looks like their price came down a bit, I'm still not sure whether I'd be willing to pay it though..
Answer: What you said shouldn't be able to be interpreted in even the most loose way as granting an unlimited licence for commercial use by simply sending you an email. If the other party wanted to take it to the wall and get lawyers involved then the issue will not be about who said what but who about who can afford to fight the longest.
However the only way to enforce non commercial use is to get a formal contract stating the exact conditions of use signed by both parties. This should apply to US and UK law.
P.S. When asking or answering a legal question you should specify which country it applies to.
Comment: Well, I am from Bangladesh and the person is from Chile I guess but hes residing in Australia right now... see? its a little complicated in terms of country! lol...


Do you use the word "that" too much?

Question: I find myself using the word "that" too much.  How do you really know when you need that "that" word there?  Like just now.  I don't think I need "that" there.  Do you have words you overuse?
Comment: This is really two questions: *How do you really know when you need "that"?* and *Do you have any words you overuse?*  The former is probably better asked on the [English Language and Usage](http://english.stackexchange.com/) site.  The latter might be better phrased as a general question rather than a poll.  How about "How do I avoid overusing certain words?"
Comment: This should be make this question more general question something like "How do you know if you use a particular word or phrase too much and what should you do about it if you do"
Comment: @sjohnston a lot of rollover between the sites.  Maybe they should be combined.
Comment: This is a call for discussion, not a question. Closing for now, but [this page in our help center](http://writers.stackexchange.com/help/dont-ask) will explain why this is a problem.
Answer: Plenty of writers have little tics like this.  You may find a turn of phrase that you just fall in love with, or it may be something that carries over from the way you speak.  At various points in my life I've found myself overusing parataxis, 'although' and 'however', and probably a few others I can't think of off the top of my head.
To a certain extent, this is a matter of style.  Only if a particular phrase or word is heavily overused, to the point where it becomes noticeable to the reader, is it a bad thing.  However, there's no obvious line that you cross where style stops and bad writing begins.  It's something you just have to keep your eye on.
You've already taken the first step by noticing that you frequently use a particular word.  In some cases, you may not realize it until someone points it out.
My advice would be to not worry about it too much while you're writing.  It's already in the back of your head.  If you notice that you're really abusing it while you're in the process of writing, feel free to make some adjustments, but don't pause for half an hour just to decide if "this" is really necessary.
The best time to work on these tics is after you've written a chunk of prose.  Go back through what you've written and look for the tic.  All modern word processors have a Find feature (usually ctrl-F or command-F) that you can use to quickly find all examples of a particular word or phrase.  As you edit, you can double-check each spot by trying to rewrite it without the word, and comparing it to the original.
If you really have a hard time deciding, it pays to have a few trusted readers who can take a look as well.
Answer: In editing hundreds (maybe thousands) of articles, I've found all authors have some kind of authorial tic: expressions that they use a lot, a tendency to use one verb tense over another, etc. Sometimes this is part of their personal voice; other times it's too much.
When you're writing, don't worry about it. Just get your thoughts written down on the page.
The time to remove your Needless Words is during the edit process. Nearly always I have to take out the word "really" from my own essays; that's the word I'm most likely to overuse.
Answer: Have you ever come across a website called autocrit.com into whose web forms you surrender your latest draft so that the site may return a list of excessivenesses from your prose: things like, "You used six initial ing words. Try to remove at least four"? Or "You had only two instances of that and four of was/were. Good job!"
In one writing forum, the algorithm got reviews along the lines of "don't believe what it tells you" and "AutoCrit will ruin your writing!" I never purchased the large-scale AutoCrit service, but I feel okay surmising that it was less a prose killer than a tool that took care of CTRL+F for you and offered a statistical reminder of the line that @sjohnston was talking about in an earlier answer, an indistinct line separating style from unmindful recurrences.
I think it's a good thing you do, watching out for that the pronoun, that the conjunction, even that the adjective and adverb. With so many uses for the little tyke, it in particular needs an eye (or an ear) on its lookout (or soundout).
Answer: If you want to know, if you use particular words too much, count them.
I gave one answer where I explain a revision process from Andreas Eschbach. At point four (marking filler words) you also can mark words like "that" or other suspicious candidates. When you have done that, count them and put that info into an Excel sheet. Over time you will see which word you use how often, especially compared to the other words.
If you find out, that you use "maybe" 1000 times when you used in the same text "perhaps" 10 times, then maybe you use "maybe" too often. You can decide , if you want to replace it with alternatives (like "perhaps" if appropriate) or just remove it.

Do you use the word "that" too much?


Do photons actually generate a slight kinetic force?

Question: My question is even though photons have no (rest) mass, do they emit a external force due to EM radiation causing electrons to be excited and jump to higher energy shells which electrons have mass thus photons can emit a kinetic force? I am new so I would like to get the record straight on this issue.
Comment: Essentially a duplicate/variation of [this](http://physics.stackexchange.com/q/2229/2451) Phys.SE question and links therein.
Answer: They do: see radiation pressure.
Photons have momentum, even in classical electromagnetism, and so they can apply force to particles. In quantum mechanics, the force per photon is $\hbar k$, where $\hbar = h/2\pi$ is the reduced Plank's constant and $k=2\pi/\lambda$ is the wavevector. This force shows up in many situations. For instance, in my experiments, the momentum kicks from photons scattering off atom can push and even cool the atoms. The effect can be substantial: rubidium atoms can be accelerated by $10^4$ m/s${}^2$ by spontaneously scattering light (a momentum kick $\hbar k$ on a mass $m$ at a rate $\Gamma$ gives an acceleration $a = \Gamma \hbar k/m$, where in this case $m=1.4\times 10^{-25}$ kg, $\Gamma = 19$ MHz, and $k=8.1\times 10^6$/m).
In contrast, the effect of light scattering off massive mirrors is much smaller, but has been measured in sensitive experiments. This effect is of paramount importance in gravity wave detection, e.g. LIGO, where the slight change in distance between two mirrors could be a signal of gravity waves. The pressure exerted by the light on the mirrors must be understand and in some situations limits experiments.
Answer: Photons can exert force on matter, a phenomenon known as radiation pressure. However it is not the kinetic energy of a photon which excites atomic electrons into higher orbits. Instead the photon has a certain energy E=hv (where v is the frequency), when a photon with an energy corresponding to the energy difference between one 'orbit' and another is absorbed by the atom it will excite that electron to a higher level instantaneously ( a quantum transition), once in this excited state, the atom can spontaneously de-excite by releasing a photon with the same energy once again returning to the lower energy state. The instantaneous transition is know as a quantum jump or leap and cannot be explained by classical physics. The noble prize for physics last year was awarded partially for witnessing these quantum jump.
Comment: i mean when the electrons jump to higher energy states doesn't the magnetic attraction to the nucleus slightly push the nucleus in one direction causing a "slight" kinetic force or is that the electron technically exerting the kinetic force?


Is it possible exchange points between players using Game Center?

Question: I want to create a turn based two player game. In my game in a certain stage if player 1 loses he must give few points that he have to the opposite player. The game is implemented with game center. Is there any possibility that I can do this point exchange via game center. I am also thinking about creating a local DB can some one help me with the best possible way.
Answer: I dont know the version of the sdk you are using, but in the latest version Game Center now support multiplayer games, witch means now Game Center can handle all data exchange.
Take a look at this tutorial: How To Make A Simple Multiplayer Game with Game Center Tutorial: Part 1/2
Comment: if this answer helped you, please consider accepting it and up-voting it. This increases your accepting rate and motivate other users to respond your other questions (and also gives rep)
Answer: The ammount of "points" stored in the GS is always an integer number.
1500 points (I noticed that some funny boys hacked the game highscores for the IOS game "Temple Run" putting the maximum possible integer 237~.
Anyway a simple script would handle that example:
If player A wants to give $x= '1000' points Then
Check if Player A point count =< $x
If False end
If  true add value -$x points to Player A point count
and Add value $x to player B point count
END


booting from linux CD and visiting https website only

Question: my friend wants to make sure he visits certain websites very securely. Is booting from linux cd and visiting only https website secure, meaning only he'll have access to data? He'll be on wi-fi of home router that is WPA2-Personal as security type.
Comment: To answer this question you need to define what level of security you want/need. Prevention of malware and assorted stuff, or prevention of someone snooping traffic, etc.
Comment: @SteveS, It's for his banking need. Protecting the data is the goal. Does that help?
Comment: @progtick, pardon me for saying so, but he'll want to protect transactional access and not data.  The actual data (balances, possibly account numbers) isn't generally useful, but the ability to log in and transfer money is.
Comment: @progtick, the account number and routing number are printed on every check written against that account.  It's not protected information; misuse of those numbers is an anti-fraud effort and not a preventative security effort.
Comment: @gowenfawr, are things like account number etc. not useful for any country's banking? (I don't know how banks operate in different countries.) He has protected transactional access too, but I'll ask him.
Answer: Yes, this is a good, pragmatic approach that should provide a reasonable level of security against many threats that he might face.  It is not perfect (for instance, it doesn't prevent the sites he visits from including external resources over HTTP), but it's probably good enough for most purposes, including, e.g., online banking.
If he uses Firefox, if he can arrange that the copy of Firefox on his bootable Linux CD has the HTTPS Everywhere extension installed, that would be a nice addition.  HTTPS Everywhere is intended to help direct you to the HTTPS version of popular sites that are accessible over HTTPS.  But this may be unnecessary, depending upon his habits.  For instance, if he only views one or two web sites, and is careful to always type "https" into the address bar, then HTTPS Everywhere may be unnecessary.
If he also needs to protect his privacy or anonymity, he might consider using Tor's Live CD, which comes bundled with Tor for anonymity.
P.S. See also the question on Secure Linux Desktop.
Comment: For complete tin-foil hat security, he needs to make sure that his ISO image is up to date with certificate revocation lists though
Comment: @symcbean: That's no tin-foil, CAs (or certificates) happen to get revoked every now and then (e.g. this week's DigiNotar disclosure, or Comodo a few months before that, or that Etilasat thing before that). Although the current MITM attack seems to be targetted geographically, I imagine there would be huge demand for such fraudulent certificates. Say hello to Firesheep again.
Answer: WPA2-Personal when used with weak passwords is vulnerable to brute force attacks. Using a random password of sufficient length or using a very long passphrase will provide some protection against these types of attacks. Aditionally, regularly reviewing the WiFi router's logs will aid in detection of malicious use.
Keep a written record or printed out page of the fingerprint of SSL certificates you use for high value sessions. Limit this to a very few sites and check the SSL fingerprint before performing any critical actions.
For banking and protection of financial transactions, limit transactions over a certain amount to in branch only. That will limit the liability of single transactions. Another useful precaution is to ask the bank to call your home/cell number to verify transactions over a certain amount. I agree with @gowenfawr 's suggestion to limit online capabilities to viewing account balances and not allow transfers to be initiaited from online sessions.
Answer: @DW's response is a good one. He did mention that there is the possibility of sites redirecting you to HTTPS, and if the user types in HTTP URL's directly by mistake (they are the default, after all), he will wind up with unencrypted requests. HTTPS Everywhere, as DW points out, is a big help, but it isn't perfect.
Another way to approach the problem (depending on your friend's needs) may be to get a VPS somewhere for, say, $20/month, and to run OpenVPN to that server (with split tunneling disabled, of course), and to NAT all browsing traffic through that server. This should provide some degree of safety regarding DNS resolution as well as privacy from snooping by others in the packet path between the computer and the OpenVPN VPS.
The questioner didn't say whether or not sniffer-resistance was a major concern, so this may be entirely off point, but this setup has worked well for me in the past.
Answer: It is harder to keep up-to-date with security patches when booting from CD.
Using a read-only OS will indeed protect against a number of attacks, and is particularly suitable for server deployments which use a relatively small software base that doesn't get many security updates.
But when the whole X11 and desktop and browser stack is pulled in, the frequency of security updates becomes larger, and the overhead of re-burning a CD every time an update comes out may get out-of-hand.  Many banking sites also rely on flash.
It may be easier to boot from a USB stick with a physical read-only switch, or some other media that is easier to keep updated.
Google's Chrome OS, and the related Chromium OS, are relatively new, but may be a good alternative if you have suitable hardware.  On supported hardware it takes advantage of TPM protection to more conveniently verify boot integrity, and has a number of other good hardening features.
See e.g.

Google Chrome Blog: Chromebook security: browsing more securely
Security Overview - The Chromium Projects

Note however that there are still risks, and the project is still young.  E.g. the 2011 Blackhat conference had a presentation on how extension bugs and XSS can still lead to nasty security breaches:

MATT JOHANSEN + KYLE OSBORN - Hacking Google Chrome OS


Two-dimensional quotient singularities are rational: why?

Question: I've read that quotient singularities (that is, spectra of invariant subrings of finite groups acting linearly on polynomial rings) have rational singularities.  Is there an elementary proof of this fact in dimension two?  I have one proof, but it uses big guns like Grothendieck spectral sequences etc.
Answer: Let me add a quick proof, also working in characteristic zero, that doesn't rely on classification (this proof is essentially originally due to S\'andor, see his Duke paper on rational singularities).  It does rely on canonical modules and a certain functoriality for them.  I will use the following characterization of rational singularities though (which I believe is originally due to Kempf), $Z$ has rational singularities if and only if it is Cohen-Macaulay and for a resolution $\pi : Z' \to Z$, we have $$\pi_* \omega_{Z'} \cong \omega_Z.$$
Suppose that $R \subseteq S$ is the invariant subring of some finite group action.  We know $f : R \to S$ splits as a map of $R$-module (trace map splits everything).
Take a resolution $\pi : X \to \text{Spec} R$ and another proper birational map $\pi' : Y \to \text{Spec} S$ such that $f \circ \pi'$ factors through $\pi$ (we can always do this, we can even assume $Y$ is also smooth if we feel like it).  So $f \circ \pi' = \pi \circ \eta$ and $\eta : Y \to X$ is some proper map.
Now, we have the following map
$$\pi_* \eta_* \omega_Y \to \omega_R$$
which can either be factored as
$$\pi_*  \eta_* \omega_Y \to \pi_* \omega_X \to \omega_R$$
or
$$f_* \pi'_* \omega_Y \to f_* \omega_S \to \omega_R.$$
In the second factorization, the first map is surjective because $S$ is regular and the second map $f_* \omega_S \to \omega_R$ is surjective because $R \to S$ splits (that map can be obtained by applying $Hom_R( \cdot , \omega_R)$ for instance).  Thus the original map is surjective and so is $\pi_* \omega_X \to \omega_R$.
If we want to prove rational singularities, we now just need to prove Cohen-Macaulayness.  But that is obvious for normal surfaces.  Of course, the Cohen-Macaulayness of a summand of a regular ring is also pretty easy ($H^i_{\mathfrak{m}}(R) \to H^i_{\mathfrak{m}}(S)$ injects).
Comment: Thanks, Karl.  This is the sort of proof I knew had to exist.
Answer: In positive characteristic, quotient singularities need not be rational. For an example, see Artin's paper "Wildly ramified Z/2-actions in dimension two".
In characteristic zero, quotient singularities are log terminal, and log terminal singularities are rational.
The first fact is a simple exercise on discrepancies (which I think first appeared in a paper of Shokurov), basically a straightforward application of Riemann-Hurwitz ramification formula.
For the second one, an elementary proof is contained in the book of Koll\'ar and Mori.
Answer: For dim 2 and field $\mathbb{C}$ the calculations are elementary. First one proves by elementary group theory that the only finite subgroups of $SL(2)$ are the Cyclic, Dihedral, Tetrahedral, Octahedral and the Icosahedral groups. Now for these one can by hand write down the equations for the quotients. Look at the nice article by Slodowy titled Platonic solids, Kelinian singularities and Lie groups. Also isolated rational singularities on surfaces were classified by Artin and include the above. Look at the paper of Artin "Isolated rational singularities on surfaces".
Answer: Well, Avan's answer covers crepant quotient singularities. There are also non-crepant ones coming finite subgroups in $GL_2$. You can handle those in a similar way. The part of the finite group contained in the center of $GL_2$ acts torically and so you can check that the quotient by this cenral piece has rational singularities (as does every toric variety)  by simply writing a toric resolution. After that you have to pass to a quotient by the image of your finite group in $PGL_2$ and there you can run again Avan's prescription.
Also, I may be missing something here but let me mention that the fact that the singularities of affine quotients by reductive groups are rational (in any dimension) is a well known theorem of Boutot and Hochster-Roberts:
J.-F. BOUTOT, Singularites rationnelles et quotients par les groupes reductifs, Invent. Math. 88 (1987), 65-68.
M. HOCHSTER AND J. L. ROBERTS, Rings of invariants of reductive groups acting on regular rings are Cohen-Macaulay, Adv. Math. 13 (1974), 115-175.
Answer: Let's assume the characteristic is $0$.
Let $R$ be a normal $N$-graded ring of dimension 2 with homogenous maximal ideal $m$. Then $R$ has rational singularity if and only if the non-negative degrees part of the graded local cohomology module $H_m(R)$ vanish. That is $H_m(R)_{(i)}=0$ for $i\geq 0$. This is due to Watanabe, see Theorem 2.2 in:
http://www.ams.org/tran/2003-355-03/S0002-9947-02-03186-0/home.html
It is safe to work in affine situation, so let $S=k[x,y]$ and $R=S^G$. Then $R$ is normal and generated by forms of positive degree. Since $H_{(x,y)}(S)_{(i)}=0$ for $i\geq 0$, it follows that $H_m(R)_{(i)}=0$ for $i\geq 0$ (one can compute local cohomology in $S$ by using a system of parameters  which are elements in $R$).
In characteristic $p$ one probably has to use Frobenius. Note that Boutot's theorem fails in this case (I think it is still true for finite group though).
A truly easy proof is probably not easy to find unless one has a truly elementary definition of rationality.
EDIT: There are other ways to see this:
II) Again, assume $k$ is algebraically closed of
characteristic $0$.Let $S=k[[x,y]]$ and $R=S^G$. Then the following 2 facts will suffice (using same notation as above):
1) There are only finitely many indecomposable reflexive modules over $R$.
(Proof not hard, they have to be summands of $S$). In particular, the class group of $R$ is finite.
2) Since $R$ is complete, $R$ has rational singularity is equivalent to the class group of $R$ is finite. This is Theorem 17.4 in Lipman  paper  on rational singularity.
III) Finally, one can quote Prop 5.15 of Kollar-Mori book on birational geometry. It gave the exact statement, but the proof uses general machinery, and probably close to what you already knew.
Comment: The link to Lipman's paper at `springerlink.com` is broken. Possibly it should point to the following one—? _Lipman, J._, [**Rational singularities, with applications to algebraic surfaces and unique factorization**](https://doi.org/10.1007/BF02684604), Publ. Math., Inst. Hautes Étud. Sci. 36, 195–279 (1969). [Zbl 0181.48903](https://zbmath.org/?q=an:0181.48903).


Is breathing in deodorant fumes dangerous for my brain?

Question: I noticed that I sometimes get dizzy when I accidentaly breathe in too much Axe. Also, I find the smell of alchohol rich deodorants quite unpleasant. But, I was wondering, is it actually dangerous? Can some chemical (alchohol) pass the blood-brain barrier and hurt my brain? Can it hurt other organs? It might be that I'm just dizzy because of the lack of oxygen...
Comment: I don't know, I was just saying that alcohol (specifically ethanol) has no problem passing the BBB, I am not sure about doses etc. in deodorants, sorry.
Comment: I think there is no doubt alcohol passes the BBB, that is how you get intoxicated when you drink it.
Comment: But can such miniscule (assumption, correct me if I'm wrong) amounts of alchohol a) actually pass, and b) hurt me in a significant way?
Answer: You can definitely absorb alcohols by breathing them in.  But doing do is far less efficient than drinking alcohol, so you don't have anything to worry about on that front.
To address your concern we have to answer two questions: how much alcohol is transfered per unit time and is there a local dosing effect due to proximity to the blood brain barrier.
It is probably pretty obvious that while alcohol evaporates rapidly compared to water, it still takes quite awhile. Imagine trying to inhale a glass of whiskey. You would get a serious headache but 30 minutes in you would still have an almost full glass of whiskey and no alcohol buzz. For an amusing anecdote relating how hard it is to get drunk off of inhaling even from a machine designed for it, see here
As to the second point - Fortunately, the blood brain barrier is a two way street for alcohol, which means that you can't get drunk in your brain if you don't have high levels of alcohol in your bloodstream. The two would dialyze into a reasonably balanced equilibrium.


How to install wireless antenna TP-LINK TL-WN722N?

Question: TP-LINK TL-WN722N is a usb antenna for wireless network.
The antenna cames with a cd for windows (and works just fine), but how can I install it on Ubuntu? It's not recognizing alone.
Comment: execute `lsusb` in a terminal and udpate your post with this information of this command
Answer: Ok good news and bad news the good news is in most cases you dont actually need to install drivers for things in Ubuntu because the Linux kernel has a lot of drivers built in, the only cases where you may need to install drivers are for graphics cards and network cards(not so much).
So the bad news is if you have the card installed fine and Ubuntu itself doesnt offer the driver to you and its not recognizing it, then we dont have the driver. Your best hope is to try a later release of Ubuntu and hope someone added the driver for your card. Its a real pain but it doesnt happen to a lot of people in recent times.
So in short you'll more than likely have to wait and see or ask the company who make the card if they can make the driver.
Answer: You are going to need the compat-wireless drivers and relevant patches. Google "ar9170 driver" for all the necessary links(don't remember off the top). I have this working great in Ubuntu 10.10 with the aircrack-ng suite and WiFite. Make sure you dl compat- wireless and unpack 1st. Then dl patches(including "negative-minus-one-maxim") to the same directory. The rest is easy as per the links.
Hope this helps. Worth going through as this is the best adapter I've found when working properly.
stamphead1


Which druid profession is best in the long run: Skinning/Leatherworking or Herbalism/Alchemy?

Question: I'm looking for the profession that will be the best for me to have once it's developed pretty high.  As a druid will it be more beneficial to use the alchemy approach, as consumables will likely cost a lot at the AH?  Or will leatherworking make me so much money that it won't make a difference?  Alchemy seems the most useful now and in the long run, but is leatherworking a better route for the money?
Answer: It depends on what you're looking to do.
If you're looking for min-maxing your stats, you'll want to ditch either Skinning or Herbalism entirely from that list. The passive bonuses from those professions are far below what the other professions offer.
If you plan on tanking, Mining is the only gathering profession worth anything. Still a bit below what you can get out of the other professions, but 60 stamina from max level Mining is a very good passive bonus while being able to retain a gathering profession. However, if you don't plan on tanking, Mining is not ideal, and unlike the other professions, you can't "switch" the bonuses per spec (like using different Dragon's Eye cuts as Jewelcrafting, for example).
In terms of Alchemy vs. Leatherworking, both offer their own unique benefits.
Alchemy will provide you with increased flask duration and effect (2x duration, and 1.5x the bonus effect). Alchemy also provides you with the means to create said flasks (and potions that you'll inevitably use). Even if you're forced to buy the materials raw, you'll end up saving by making them yourself rather than buying the finished product on the AH. Additionally, as alchemy, you have the ability to learn how to transmute epic gems on a 20 hour cooldown (basically 1 a day).
Leatherworking will provide you with a unique-to-leatherworking wrist enchant, either attack power, spell power, or stamina (DPS, caster/healer, and tanking choices, respectively). Additionally, you can make extremely cheap leg enchants for yourself only. While they are no different than the ones that you can make for others in terms of stats, the material cost to enchant your own legs is very low comparatively. Lastly, you can learn/make the epic leatherworking pieces in the end game which are expensive to craft but also very useful pieces to multiple class / spec combos.
In terms of money making, your best bet is going to be Jewelcrafting, Alchemy, or Inscription. They have the items that people always come back for and need on repeated and frequent basis. Note that Inscription will likely not be in this category in the upcoming Cataclysm expansion, as recent news has indicated that Glyphs made by Inscription will not be constantly replaced, but rather a 1-time-learned-forever-retained thing.
In terms of min-maxing stats, it's slightly dependant on your class/spec, but your best bets are Jewelcrafting, Blacksmithing (combined with Jewelcrafting), Tailoring (for casters/healers), and Engineering (for DPS classes, though the utility gain through Engineering is useful for everyone).
Answer: Both could make you money on the AH with the right strategies. I imagine alchemy would be easier, though, since consumables by their nature are always in demand.
That said, I don't think this question has a single right answer -- your outcome would depend on your ability to turn stuff into gold and your server's economy. I'd make this post a community wiki.
Answer: I have an 80 resto druid and personally I'd choose Alchemy. It would be more useful for yourself, friends, and guild because you could provide battle elixirs and pots for the group. It also can make you plenty of money and is relatively easy/painless to level. Especially once you get flight form because you can pick herbs while flying! Also, herbs are everywhere, whereas skinning can only be done on certain mobs.
Answer: I've found that Alchemy has been a great bonus for both of my druids (one Feral, one Resto/Boom).  The longer duration flasks is fantastic for raiding, but you also get a bottomless flask for use in Heroics, questing, light PvP, etc.  Flask of the North isn't as good for Feral (+40 STR) as it is for casters (+47 Spell Power), but it is still a nice bonus, and it can be used over and over.  Money is also nice from both Flasks and Transmutes.  I have one spec'ed into each.
For me, the +40 Crit from skinning would be nice on Boomkin, but I don't need it as much on Feral or Resto.  For Feral DPS (off-spec to tank), I sit at about 56% crit, and +50 Crit is ~2% additional crit.  A nice bonus, for me the extra time and contribution of Flasks is more important.
As for Herbalism, druids do have an advantage over other classes.  You don't need to change out of flight form to gather herbs, so you are able to save time mounting and dismounting at each point.  It is only a minor bonus, but I find it nice.
Answer: I think skinning and leatherworking are a better combination if you are playing DPS as a Druid. Skinning increases your crit chance, and with leatherworking you can make something for you or just sell it if you need money.  Armor kits that you can make through leatherworking are very beneficial as well for all specs.


lsmod returns error unless called with sudo

Question: Fixed: The install README for libusb suggests added a call to
export LD_PRELOAD=/path/to/libusb-driver.so

It was this .so file that was getting called and interefering with lsmod (and it turns out some other commands as well). To fix this I moved the libusb-driver.so file to the Xilinx/.../common/bin/lin64 folder. All tools can access the cable without sudo calls.
In addition I found that the Xilinx settingsXX.sh script was breaking my PATH. Changed this script to append to end of PATH instead of front of PATH.
Thanks Y'all.
Fedora 17, Linux 3.4.4
After installing the Xilinx cable drivers, which didn't work with Linux 3.4.4 I installed the libusb solution. The cables detect and I can access them from within the Xilinx tools. However, now everytime I try an lsmod I get the following error:
libkmod: kmod_module_get_holders: could not open '/sys/module/windrvr6/holders': No such file or directory
windrvr6                   1  -2

libkmod: kmod_module_get_holders: could not open '/sys/module/parport_pc/holders': No such file or directory
parport_pc

sudo lsmod does work, and these modules are not shown as loaded. rmmod reports that the modules aren't loaded.
I have poked around /sys/module , /etc/modprobe.d and a couple of locations I can't recall at this second. I can find no reference to windrvr6 anywhere.
Any suggestions about how to remove calls to these modules would be great.
I also tried making a new user and the problem persists there. I logged in as root and the problem persists there as well, unless I call lsmod with sudo, it errors.
Thanks,
Camille
Comment: Is there a special `lsmod` in `/etc/sudoers`?
Answer: Fixed: The install README for libusb suggests added a call to
export LD_PRELOAD=/path/to/libusb-driver.so

It was this .so file that was getting called and interefering with lsmod (and it turns out some other commands as well). To fix this I moved the libusb-driver.so file to the Xilinx/.../common/bin/lin64 folder. All tools can access the cable without sudo calls.
In addition I found that the Xilinx settingsXX.sh script was breaking my PATH. Changed this script to append to end of PATH instead of front of PATH.
Thanks Y'all.


How do I counter an ACU rush in Supreme Commander 2?

Question: ACU rushes are really annoying. How can I counter them?
Answer: I agree with RCIX's point about the radar, and possibly some aircraft/tanks on patrol for spotting.
However, I find that this is often like a "queen swap" in chess; in the early game you can usually only defend against it by sacrificing your own ACU. Although, if your ACU has enough research on it it may well survive taking out their ACU before it gets to your base.
Answer: You really should start with building radar so you can see if they're ACU rushing. From there, if they are, drop everything and start building some point defense. If you have factories, then halt them and order the closest one to put up a factory shield, then build under that. 3 PDs will counter an unupgraded ACU and 5-7 will counter an upgraded one. If they get overcharge, your best option is to get shields and deploy several of them in your base.
Answer: My suggestion is that if you find an ACU rush from a distance, deploy a factory away from your base at a choke point, then quickly deploy a shield generator from an add-on. Add PDs (as many as possible) underneath the generator, and then, if you have some time, build some units for chasing your opponent if they run. Make sure you use a couple engineers for this, not the ACU, or else you're making the opponent's job easier. By the way, if you didn't know, engineers can assist a factory to build units/add-ons faster. Hope that helped!
Answer: Scout to see it coming. Build point defence inside the shields of your factories. Build tanks, lots of them.
Worst case you can send your commander to his base and capture everything, and take it from there.


how to calculate more efficient volatility figure than historical volatility?

Question: can we use alpha value to calculate option price instead of historical volatility.
And if we can please explain how. I am doing my MMS in Finance and this for a project i am doing. the project is about tweaking the black scholes formula on option pricing.
Comment: What is "alpha value"?
Comment: Does your question imply that you do not have access to option market data you can derive implied volatilities from? (i.e. you only have the underlying market?)
Answer: The standard realized volatility calculation assumes an underlying model: geometric Brownian motion with constant drift and volatility. Then realized vol squared is an unbiased estimator of the process volatility squared.
If you want to move beyond Black Scholes then you have two possibilities: look at a different formal model and the estimators for its values; or assume that volatility is stochastic but varies more slowly than your estimation window, so you can (roughly) assume it's constant for that window.
I think by "alpha value" you're referring to the alpha parameter in the GARCH model? There are lots of references on estimators for GARCH process parameters, though I don't have any at hand right now. Trying googling for GARCH estimation.
In practice, though, people do the second more than the first, even though it's difficult to justify formally. One way you can give yourself more confidence there is to use a more accurate estimator of realized vol than the usual close-to-close one, since then you can use a shorter historical window for the same uncertainty on your volatility estimate.
Two usual ways there: use regularly-spaced data that's more frequent than close-to-close (eg sampled every 10 mins from realtime data); or use high-low-open-close (HLOC). There's a really cool paper by Garman and Klass on estimating vol using HLOC data which I love, and gives an estimator with a variance about 9x smaller than the variance on the close-to-close realized vol estimator (so std dev of the estimate is ~3x more accurate):
http://www.cims.nyu.edu/~ra1221/riskPortfolio/garmanKlass.pdf
Comment: Yeah, I quite liked using the drift-independent volatility estimator outlined here: http://www.atmif.com/papers/range.pdf

But as others have commented, I don't think this is quite what is being asked.
Answer: Black Scholes makes the assumption of deterministic (time varying) volatility of the underlying asset. Also, the volatility input to the option pricing model is implied by nature and does not rest on realized historical volatilities. Think about it, the whole notion of being able to price a derivative with contingent future payoff rests to large degree on the assumed future variability of the underlying asset.
Therefore if you look to make changes to the Black Scholes framework then you can start with modeling implied volatility, not historical realized volatility. The next step would be to relax more assumptions of the BS framework to account for discontinues jumps, varying interest rates, different dividend models, and such forth.
But try to remove yourself from considering realized volatility metrics as they are of no use to the BS framework unless of course you utilize historical volatility to model your implied volatility which you then plug into BS.


Graph API and Dynamic Access Tokens

Question: So basically im making an app which i need to embed a custom facebook wall feed into. I just want a JSONP response... that is all.
From reading for days on access token's e.c.t. i've come to the conclusion there is no way to use the graph API without a valid access token, however i dont want to require the user to login (the target platform doesn't lend itself to easy character input, plus id have to create a custom popup keyboard and interaction JS).
So the only option i've found is to use the access token for the app i setup in facebook. However i do not want to distribute the app secret so i can use the APP_ID|APP_SECRET method i've seen method (whatever it is exactly) as that would mean bad things i presume?
So my idea is, to create a proxy script on a server, which will hold the app secret e.c.t. This script will ask FB for an access token, and pass that back to my app so my app can get the wall feed and continue to use that token for refreshing the feed.
If i open my app and get an access token, then another person opens my app and gets an access token, will my access token expire as a new one has been generated? Or can you generate as many access tokens for the same app as you like?
Or can anyone think of a better approach?
WORKFLOW

User opens app on device (the device is a bespoke contained unit, think of a Raspberry Pi but 100x simpler, and its plugged into a tv)
The app loads a number of feeds into area's on the page, these feeds include facebook wall feed from a specific profile.
The app will run unattended for days/weeks/months and refresh the feeds of information periodically.

FB Access Token Workflow
Since the user cannot login, i need to provide an access token. I do not want to pass round my app secret for the sake of security. So my idea is to use a php proxy script hosted on my server to get the access tokens. Like so:

On first load the app with run a function which does an ajax call to my php proxy script requesting a token
My proxy script will fire off a request to facebook with my app id and secret, and get a access token back from FB
My proxy script will then dump that access token back as a jsonp response to the app
The app will grab the access token from the jsonp response, and store it
The app will use the retrieved & stored token for all wall feed requests to the facebook graph api.
If app detects its token for some reason doesn't work, it will attempt to get a new one from my token proxy script.

That is my idea for how a token proxy script could be used to give access tokens to everyone, without giving away information which would cause issues if someone looked at the app source code (which wouldn't be difficult at all). However if facebook deletes old tokens every time you request a new one, this wouldn't work. So that is the immediate question.
However if theres a better way around the issue, my ears are open. Thanks
Comment: Your question, or i mean the way you explain the question seems a bit complex. Can you please mention the workflow of how this is going to be working? Like, 1. user comes to your site. 2. blah blah. so and so.
Comment: @Kishor: Ive added some extra information on the app process and the proposed token fetching idea. Hopefully it helps clear things up?
Answer: I am not sure if you would be able to do what you want with an App access token.
1) App access token doesnt have access to everything that the user has access to, or what you can access using user_access token. Like, some age restricted pages, so and so.
2) Quoting from the documentation :

Note that the app access token is for publishing purposes permitted by
  the publish_actions and publish_stream permissions. You will be unable
  to retrieve information about the status update post with the given ID
  using the app access token. Instead, you should use a user access
  token for such purposes.

3) The retrieval ability using app access_token is limited to,
a.Basic Profile Info of a User (ID, Name, Username, Gender).

b.A User's Friends and their IDs.

c.Permissions granted by the User to your App(probably includes email, etc etc.)

So, I am not sure if its going to work for what you are looking for. But if you can have the user login first, and make the user go through the auth(he wont need to login) once every 60 days, you can use extended user access_tokens.
If you are going that way, this will help. Its some other question I answered dealing with a cronjob. Read : Facebook PHP post to fan page with cronjob?
Hope this helps

Graph API and Dynamic Access Tokens


What are Reapers good for these days?

Question: Since Patch 1.1.2, the Turbo Reaper has gone away.
What are pros using the Reaper for these days? Just an early scout?
Comment: except, a sentry *always* brings friends..
Comment: Some fun facts: one on one a reaper beats a hellion (without blueflame that is), and a reaper beats a sentry in a one on one fight.
Comment: @Bora, early game there may be just a sentry and a zealot when you arrive, allowing you to snipe the sentry then kite the zealot. But yeah, you don't get lone sentries too often, but if you do it is good to know you can kill it!
Answer: Early scout, mid-game scout..
They are also still good for harrassing the mineral line, especially on vertical terrain.
Comment: +1 for "scout + harass". In recent pro games, I've seen these used effectively for random scouts to save energy for MULEs. In the early game, you can usually pay for your reaper by sniping a few drones then pulling back until you need another scout update.
Comment: This. They are also fairly good at punishing players protoss players that are slow to tech to stalkers and sentries.
Answer: When you get +1 weapon upgrades, 2 reapers one-shots the workers.
So you can easily do some serious damage with just 2 reapers if you can manage the surprise the opponent.
I won some good games with just this tactic. Sneak 2 reapers, kill 6-8 workers in seconds and voila!
Comment: That's probes only, right?
Answer: Reapers are still effective as anti zergling/zealot/marine units, in any situation where they are not easily reached by the enemy.  They are particularly useful vs. tier 1 melee.
Reapers do tremendous damage to light units. Unfortunately, their range is short, they have few hitpoints, and they like to race ahead of your army.  Consequently, when mixed into a terran mass, they run to the front and immediately die.  Reapers only work in situations where you can afford to manage them heavily.
In team games, hard, early tier 1 rushes are common.  If you scout that your opponents are planning one, padding your army with reapers can be effective. They are available faster than siege or other defense alternatives, and have good mobility for defending your partners.
You can assume that the opponents plan a double tier 1 mineral-heavy rush if their early bases fit the following profiles-

protoss builds 2 gateways before his cybernetics core (or has no gateways at all)
zerg's spawning pool researches fast zerglings
terran builds 3 or more barracks before a factory

If you scout this situation and have not been planning a hard early rush yourself, you'll need to quickly change gears to deal with it.  A few reapers will cut through a force like this quickly, if the reapers can avoid direct contact with the enemy.  They can either be placed in a bunker if you need to defend your own base, or used on the outskirts of the battle, trimming the edges of the enemy if they try to advance on your partner.
If it the opponent starts to heavily mix in roaches, stalkers, or marauders, send your reapers out to harass peon lines, and switch to marauder production. Reapers should never, ever engage armored units.
Answer: For early game timing attacks send the Reaper to harass the mineral line, then send your main army and attack the front.
Often players will send too many units to deal with the reaper and you can more easily kill their main army.  If they don't send anything, your reaper can do massive damage on the mineral line while your opponent is busy.
Answer: Reapers can also be used to get line of sight up a ramp, useful for if your army is blocked by a strong wall-in or forcefields, or you're trying to siege tank his base and can't see the highground. Also handy in 2v2 for helping your teammate warp in uphill etc.
Answer: Reapers can be used in a variety of ways, I tend to use them for fast worker harrass and scouting xel'naga towers. Also due to there quick speed a do use them to attack expansions of the opponet and lock them in there base. Overall reapers are good early to mid game for harrasment and scounting, but in late game zerg and toss tend to have ranged units e.g. blink stakers and mutas which make them less effective.

What are Reapers good for these days?


Game thread, render thread, animation/inverse kinematics, and synchronization

Question: In a multithreaded setup with a game logic thread and a render thread, with some kind of skin mesh animation with inverse kinematics plus etc how does animation work? Does the game logic thread just update a number saying time T in the animation and then the render thread infers Who owns the skin mesh animation, the game logic thread or the render thread? How is it stored in the scene graph if it is stored there at all? When the game logic updates does it do the computation of the skin mesh animation and the computation of the inverse kinematics and then store the result directly in the scene graph or is it stored indirectly and the render thread does the computation?
Answer: Don't design your threading like that.  The idea of giving each system its own thread is not a good way to actually utilize the system.  Game play and rendering really do work in lock step (if there's no gameplay update, there's nothing new to render).  More importantly, there's only a few subsystems to a game engine, but there are a lot of cores in today's machine, and the core count is only increasing.
A better approach is to use a batch/job system.  Run each system in lock step, but split up the work of the systems into threads.  For rendering, that'll mostly be occlusion culling. For gameplay, it will often be path finding, and maybe ray casting and AI occlusion tests.  For physics, it'll be various islands of separated objects.
One of the only systems worth giving its own dedicated thread is audio, and that's only because audio is super ridiculously sensitive to latency and stalls, far far more so than any other part of a game.
Once you design threads around batches instead of parallel systems, the ownership problem becomes much simpler.  Instead of worrying whether gameplay or rendering owns a mesh, you instead know that only one or the other is touching the mesh at any given time.  Your rendering jobs are then split into completely isolated batches of objects, so again there's very little contention to even think about.
Comment: @MVCDS: at a cursory glance, no. I meant that (for simpler game architectures) the renderer has nothing useful to do if the physics/logic system hasn't updated the game state so even if it's on another thread it must synchronize state before it can run; likewise (for some games) the logic thread shouldn't keep updating at a high speed if the render thread can't keep up. Threading's purpose in such games is to utilize CPU resources better, not to allow the tasks to operate independently.
Comment: Is this what you mean by [run each system in lock step](https://en.wikipedia.org/wiki/Lockstep_(computing))?
Answer: First of all, the question is too complex and unclear, but I'll try to answer it anyway.
"How does animation work?" - you can design however you want.
"Who owns the skin mesh animation, the game logic thread or the render thread" - what do you mean? Threads are just execution contexts.
If you want to, with caution you can share data across threads, since all threads share the same address space ( -need to ensure no race conditions i.e. harder to design and debug; +saves RAM).
"stored indirectly and the render thread does the computation" - you can design however you want. The correct answer depends heavily on the CPU and RAM usage. If the computation is really cheap, but produces huge data set - you'll probably want to compute it on the main thread to save RAM. If however the computation is expensive but produce small dataset - you'll probably want to compute that on some other thread, store the result somewhere in RAM, and have the renderer thread get that result and update your scene graph with the new data.
P.S. I suggest you to read the following article: Designing the Framework of a Parallel Game Engine, esp. section #2. And this one: Multithreading the Rendering Pipeline for 3D Model Animation - as you can see, they choose to duplicate the modified data across threads.


How do I hide a specific volume from the desktop, but keep all others?

Question: I find the icons that show up when I plug a flash drive useful, as much as SD cards and devices. However, the icon to my Windows partition is useless. How can I hide it?
Comment: I like to add something. Is there any way, hide drive icon without unmounting that drive?
Answer: To hide a partition, mount the partitions in your '/mnt' folder.  I use the fstab file to accomplish this automatically on boot up.
Answer: Eject or unmount those which are not in use. This way, the icon will disappear from the desktop but will yet be listed in the file browser folder tree (in the sidebar) and in the devices listed. And will be available to gain access to the data contained in the device just with a clic.
This screenshot is having the SD memory connected and mounted, both the icon and the folder tree showing the device.

This screenshot is having the SD memory connected and NOT mounted, the device is shown in the folder tree but not in the desktop.


Taylor series of a modulus argument

Question: What is the definition of a Taylor series of the function $F(|\vec a -\vec x|)$ about the point $\vec a$ in $\vec x$?
Answer: As filmor notes, the Taylor series isn't well-defined if you consider this as a function of the full vector $\vec x$. If you don't mind a singularity at $\vec a$ (or if the odd derivatives of $F$ at $\vec a$ vanish), you can use the one-dimensional Taylor series for $F$ to write
$$
\sum_{n=0}^\infty\frac{F^{(n)}(|\vec a-\vec x|)}{n!}|\vec a-\vec x|^n\;.
$$
Answer: There is no proper definition for this (if you take $F(\lvert \vec a - \vec x\rvert)$ as a function of $\vec x$), as $\lvert\vec v\rvert$ is not differentiable at $\vec v = 0$ (in this case: $\vec x = \vec a$).
Answer: This definition is the same as Taylor series of function $F_2(\vec x)=F(|\vec x|)$. I'm not sure if you are familiar with vector function Taylor series. In general case the formula is kind of long, so I'll just give and example for bivariate function $f(x,y)$ about the point $(a,b)$
$$f(x,y)=f(a,b) + \frac{\partial f}{\partial x} \bigg|_{(a,b)} (x-a) + \frac{\partial f}{\partial y}\bigg|_{(a,b)} (y-b) + \frac{\partial^2 f}{\partial x^2}\bigg|_{(a,b)} (x-a)^2 + 2\frac{\partial^2 f}{\partial x \partial y}\bigg|_{(a,b)} (x-a)(y-b)+\frac{\partial^2 f}{\partial y^2}\bigg|_{(a,b)} (y-b)^2 + \dots$$
But there is still one thing, you see, the derivative of modulus ($|\cdot|$) does not exist around zero vector. So if you could give us a little more detail on why are you trying to solve a problem like that, them maybe you will get a good answer.

Taylor series of a modulus argument


Vortex street and Reynolds number

Question: Its been stated in Wikipedia regarding Reynolds number(Re) that "laminar flow occurs when Re<2300 and turbulent flow occurs when Re>4000. In another wiki file related to Kármán vortex street it has been stated that "A vortex street will only be observed over a given range of Reynolds numbers (Re), typically above a limiting Re value of about 90. According to Wiki "The term Kármán vortex street (or a von Kármán vortex street) is used in fluid dynamics to describe a repeating pattern of swirling vortices caused by the unsteady separation of flow of a fluid over bluff bodies".Doesn't this "unsteady" refer to turbulence? If so then how is it possible for vortices to have so low value of Re? Is 'more the turbulence higher is the vortex effect' a right statement?
Answer: Turbulence isn't the same as unsteadiness - a vortex street is not necessarily a turbulent phenomenon. As an analogy that (for some reason) I find easier to understand, consider a convection experiment where we heat a fluid at the bottom and cool it at the top. Below a certain threshold value for the temperature difference, the heat is transferred only by diffusion and there is no bulk flow. A little higher and we get an instability, resulting in the formation of a convection cell. In this case the fluid is moving, but it is still moving in a laminar way. As we increase the temperature difference, the speed of the flow increases, and it's only when we've increased the temperature quite a bit more that the flow becomes turbulent.
Vortex streets are similar. Above a certain value of the Reynolds number, the vortex street forms. The flow is now time-dependent, but it's periodic and still relatively easy to predict.  If the flow is increased even further then the vortices spin so fast that smaller vortices form to dissipate their kinetic energy. It's only at this point that the flow becomes unpredictable and chaotic, which is when we call it turbulent. I guess you can say something like, a Kármán vortex street is a flow that's unsteady on one spatial scale, but in order for a flow to be called turbulent it has to be unsteady across a wide range of scales.
Comment: Indeed a common misconception that a vortex is necessarily turbulent.
Answer: The point at which the flow becomes turbulent is very sensitive to the flow geometry. The value of 2,300 you quote applies to flow in smooth pipes. To take an example, the flow round a sphere becomes ceases to be laminar at an Re of about 1. The flow becomes increasing turbulent as you raise the Reynold's number until vortex shedding starts around Re = 50.
Comment: This is partially due to the choice of the length scale that goes into the calculation of the Reynolds number. We choose one that is "characteristic" of the system, but it is not obvious that this term is well defined.

Vortex street and Reynolds number


FullTextSQLQuery with a Taxonomy GUID in Where Clause

Question: I've created a few documents and tagged them with various Taxonomy Terms from a Term Set. The terms I have chosen are children of other Terms. I've executed a crawled and created a Managed Property called TaxonomyTerms which maps to all the crawled properties for the Managed MetaData fields I created.
I issue a query using the FullTextSQLQuery like so...
SELECT Title, TaxonomyTerms FROM Scope() WHERE "scope" = 'All Sites'

... and I get a data table containing all the documents I created. I output the TaxonomyTerms property and verify that all the GUIDs for the terms are in the field.
Next, I execute the following query...
SELECT Title, TaxonomyTerms FROM Scope() WHERE "scope = 'All Sites' AND
TaxonomyTerms = '#1235-6789-0123-4567'

...with the number above being a fictional GUID for the purposes of this example.
I get 0 results back from FullTextSQLQuery.
I try similar queries against the individual owsTaxIdFieldName properties and the ows_taxid_MetadataAllTagsInfo property and still received no results.
According to the syntax detailed in this MSDN article and several other blog articles I have read about writing SQL queries with Term guids, the above query is correct.
But it doesn't work. I'm kind of banging my head on the wall here. Being able to execute a query by Taxonomy GUID is fundamental to the success of my project.
If anyone can provide direction, I would appreciate it.
Answer: The query above should return the correct result.
Have you re-published the page (in SharePoint publishing scenario) and re-run the crawler?