Do aeroplanes have to balance torque like helicopters?

Question: Helicopters need a tail rotor to balance the torque reaction that tends to rotate the main body sideways. Doesnt a single-engine plane suffer the same problem? I would imagine that (for example) the left wing would dip lower than the right due to the torque. How is it countered?
Comment: Not only torque reaction. Yawing and pitching moments,  asymmetrical thrust and gyroscopic precession as described here: [Effect of Propeller on Airplane Dynamics](http://www.aircraftspruce.com/catalog/pdf/13-09032.pdf)
Answer: A single engine plane can suffer from control problems due to torque.
An early famous example was the Sopwith Camel
As others have pointed out, torque effects have to be countered using the normal aerodynamic controls available to the pilot. Some aircraft had extra-large ailerons because of this issue.
Comment: In fact, fighter pilots of the time were very aware that, due to those forces, planes could turn in one direction (the "rotary turn") much more tightly and faster than in the other. Important to know when dogfighting!
Comment: It should be mentioned that the rotary engines cause much bigger problems with precession than other types making Sopwith Camel one of the really bad cases.
Comment: Indeed, what we are seeing with the Sopwith Camel is not a simple case of propellor torque. The entire engine is rotating about a stationary crankshaft (for cooling reasons) and the acceleration of the engine is largely responsible for the rocking. According to the video commentary, the engine has no throttle and only 3 power settings (3,6,or 9 cylinders) so the pulsing is actually a design feature! It must have been vary waring to fly. Precession refers to the fact that the engine also acts like a massive gyroscope. This plane could turn much faster and tighter in one direction than the other
Answer: In contrast to what happens in helicopters, the static and dynamic stability will prevent big movements of propeller aircraft due to engine and propeller torque. The biggest consequence, the rolling moment, is taken care of by roll damping. When the propeller torque rolls the aircraft, the downwards-moving wing will see a higher, and the upwards-moving wing a lower angle of attack. Both wings will create a rolling moment which will quickly stop the rolling motion. All the pilot has to do is to restore the correct roll attitude using the ailerons.
The lift difference of the rolling aircraft also creates different drag on the left and right wings, so a small yawing moment will turn the aircraft slightly sideways when the rolling starts. This has to be corrected by rudder input.
If we look at other secondary effects, the yawing motion will cause a slight pitch change by way of engine and propeller precession. This also will be stopped quickly by pitch damping (the pitch movement changes the angle of attack on the horizontal tail surfaces), and the pilot needs to correct the pitch attitude again.
In consequence, changing RPM will induce slight movements around all three axes in a single-engined propeller airplane.
Answer: It is countered by the natural stability and the roll control provided by the ailerons. If you have insufficient airspeed for roll control then you will be on the ground and your gear will prevent excessive rolling.
Answer: There is a big difference between the amount of torque delivered to the main rotor of a helicopter and that delivered to the propeller of a comparably-sized fixed wing aircraft. Also, without the tail rotor, a helicopter in a hover has nothing to "push against" in order to deliver the needed torque to the main rotor. If not for the tail rotor, torque delivered to the main rotor would cause the rest of the vehicle to spin up in the opposite direction. Hovering flight would be pretty much impossible without something to aerodynamically generate opposing torque (tail rotor, second counter-rotating rotor, etc.).
Torque delivered to the propeller of a fixed-wing aircraft is opposed either through the ground (when stationary, taxiing or on take-off roll), or by the wings (with minor roll trim or control input) when in flight. As explained in the other answers, propeller torque does induce certain effects, but they are of much less significance than that of a helicopter main rotor, and are dealt with by trim and pilot awareness/handling.
Answer: Torque is more noticeable in aircraft with tail wheels (tail draggers) which also have large engines (e.g. world war 2 vintage) for two reasons:

If the throttle is advanced too quickly, you might not have enough airflow over the rudder to be able to counteract it and a swing followed by a ground loop could result.
At the point when the tail is lifted off the ground during the take off run, gyroscopic effects occur that could cause a swing (try holding a spinning top and then move it around - it exerts forces in unexpected directions).

Also on aircraft with the largest engines, the torque could make one wing lower than the other during the take off run. You also have the problem going around to be very careful with both throttle and rudder because these effects are more pronounced at lower airspeeds where airflow is less.
An aeroplane with a nosewheel is generally more stable on the ground (due to the CG being ahead of the main wheels rather than behind), so these effects are less noticeable.
Comment: Sorry yes you are quite right, p factor is another thing in addition to the gyroscopic effects I mentioned. Searching for "p factor aviation" gives a quick explanation from Google


Has the reincarnation of Indra and Ashura ended?

Question: Has the reincarnation of Indra and Ashura ended, after Naruto and Sasuke fight? Or will there be new reincarnation of them again, looking for new hosts ?
Comment: @NamikazeSheena The cycle won't continue until Naruto and Sasuke died.
Comment: @AnkitSharma No they weren't. Madara was dead by the time Sasuke was born. And that's how Indra's reincarnation took place. What really happened was Madara was brought back to life by Kabuto using edo tensei technique. How edo tensei works on indra - ashura reincarnation I'm not sure.
Comment: @NamikazeSheena As "Happy Face" user has mentioned, there won't be another reincarnation of Ashura and Indra until Naruto and  Sasuke die. So it's obvious that Boruto and Sarada are not Indra - Ashura reincarnation since  both Naruto and Sasuke are still alive.
Comment: The next cycle is Boruto and Sarada of course~ When they get married they'll end millenia inter-family feud~
Comment: @HappyFace Mandara and Sauske was alive at the same time.
Comment: @AnkitSharma Recall, it was a while after Madara died that obito attacked the leaf village pretending to be madara, and sasuke was barely a day or two old at the time. Hashirama on the other hand had been dead for a while, and Naruto was the first known Senju relative to be born after Madaras Death, but as well the only known one born after Tsunade who learned gambling from Hashirama
Answer: I thought that through the series it was going to be explain, what happened for the current incarnations Naruto and Sasuke, until the end of the series.
According to Naruto wikia:

The reincarnation cycle will not start again until both of the current reincarnations have passed away; the brothers would not reincarnate until Madara's death, which would occur decades after Hashirama's.

Also on top of the page, it says: Naruto Uzumaki, the current reincarnation of Asura.
The only thing that differs with Naruto and Sasuke was that they didn't have the same conclusion, as the previous reincarnations:

Ultimately, Naruto managed to accomplish what all of the previous
  reincarnations had failed to do: end the rift between the two lines of
  the reincarnated brothers. Naruto achieved this after defeating
  Sasuke, who finally accepted Naruto's ideals at the end of their
  fight. This brought about the end of the bitter feud that had lasted
  for centuries. According to Black Zetsu, the reincarnations of Indra
  and Asura were almost always in conflict with each other and rarely
  worked together. Naruto and Sasuke are one of the exceptions, assuming
  other exceptions have existed throughout the centuries.
Comment: Agreed, Naruto and sasuke were born at the same time within a few days, both the first known born of each branch after Madara officially died. They cycle will at least try to restart once they both die, but it may end if no more uchiha have kids or die before that, though its possible there are other branches that are also suitable.
Answer: This question is hard to answer with certainty.
Based on Naruto's words before the final fight with Sasuke, the feud would end after that battle.
(Chapter 692, pg 17)
Sasuke then claims the "eternal destiny the sage of six paths talked about [would] end" if he dies. Sasuke didn't die, so the "destiny" (reincarnation cycle) may still be alive.
http://narutobase.net/manga/Naruto/698/18/
Or maybe Naruto ended it by forcing Sasuke to admit defeat, something the other reincarnates of Indra never did.
http://narutobase.net/manga/Naruto/698/17/
Based on what happened when Obito died, there is a soul and afterlife of some sort, so one could argue that, with the "feud" over, there is no need for them to reincarnate again, and they could finally pass on to that afterlife.
(Chapter 688, page 6)
In conclusion, I don't think there is a definite answer. You just have to choose what to think yourself on this one.
(Chapters and page numbers from narutobase)
Answer: I would argue that the reincarnations end with Naruto and Sasuke. Indora and Ashura reincarnated probably because they still hadn't ended their feud. Because Naruto was able to end the brother's feud, that probably also ended the cycle of reincarnations. In other words, the brothers made up through their reincarnations (Naruto and Sasuke), so they have no reason to keep reincarnating again.
Answer: I'm  not predicting or giving a direct answer to the above question, but I say that the reincarnation can take place again not for the sake of any dispute between brothers like before, but for the extension of the family tree or expansion of clan and lineage...it could be now a reincarnation of brothers for the sake of watching over the true will of their dad...and also to innovate a new era with cooperation after long strife...
besides, in resolving to do dad's will from now on, madara will be free from zetsu's deceipt and darkness will not be the way out for the sharingan but Hagoromo's full powers might certainly enhance the sharingan or again, honest cooperation between the brothers can make things to run smoothly (like hashirama cells, tailed beasts' chakra ,hagoromo's legacy, etc)
therefore since there are various clans, the two bothers can incarnate as clan leaders (madara, hashirama)...and a new story emerges with their collaboration...and i think that there are still some boss battles...kaguya mentioned that she was pursued by some three violent persons and that she escaped to the ninja world where she arrived already fierce and powerful...this therefore means that madara's story of which he was convinced about kaguya eating a fruit and thus possessing chakra was wrong!?!
i think the reincarnation is possible and can be appropriate in a collaboration context...thus madara indora can be appreciated, cheered and thanked for the incarnation idea...i don't know if it will bore or it will still be interesting and have some sense (because previous boss is now walking with actor, what next?)
to be honest, if naruto and sasuke incarnates are in collaboration, with their actual power levels (ten tails and rinnegan), i don't imagine a threatening boss battle against them...even if they possess the power level below the above mentioned power level, if incarnates of madara sasuke and naruto are in collab, i still think that boss battle has been cleared in advance
Answer: The reincarnation cycle definitely ended because indra said a purpose to his reincarnation and ashura said he will also reincarnate as to stop him. Every reincarnates failed in their purpose, but with naruto and sasuke, naruto fulfilled ashura's and hagoromo's wish(indra and ashura working together in full harmony without hatred, but only with love and brotherhood). Sasuke overcame his hatred and 100% doesn't wish to do what indra wished to do, in other words, indra overcame his hatred, and ashura succeeded in helping indra overcoming his hatred. And thus the cycle of hatred also ended. So there is no reason to reincarnate anymore.
All the other indra reincarnates before sasuke doesn't agree with ashura's ideologiea, and dies while holding onto indra's ideologies leaving behind a purpose for reincarnation. That definitely ended with naru-sasu in their last battle.
Comment: Please add further details to expand on your answer, such as working code or documentation citations.


How can I a closed form for this equation?

Question: I have an equation as follows: $$[\gamma(\beta+y)+1]\exp(-(\beta+y)\gamma)>\{1-[\gamma(\beta+y)+1]\exp(-(\beta+y)\gamma)\}\alpha$$
where all parameters are positive.$$$$How can I a closed form for this equation( so as y> or < parameters of equation). I want to extract $y$ from inequality.
Thank you in advance!
Comment: How can you *have a* closed form for this equation? :)
Comment: I need to have domain of y to solve my main problem!
Answer: I do not see how to obtain a closed-form solution, but your inequality is clearly related to the Lambert W function. Let $w=-\gamma(\beta+y)-1$. Then
\begin{align}
[\gamma(\beta+y)+1]e^{-(\beta+y)\gamma} &>\{1-[\gamma(\beta+y)+1]e^{-(\beta+y)\gamma}\}\alpha,\\
-we^{1+w} &> \alpha[1+we^{1+w}],\\
-(\alpha+1)we^{1+w} &> \alpha,\\
we^w &< \frac{-\alpha/e}{\alpha+1}.
\end{align}
So, using notations from the Wikipedia page, we must have $W_{-1}\left(\frac{-\alpha/e}{\alpha+1}\right) < w < W_0\left(\frac{-\alpha/e}{\alpha+1}\right)$ (where $W_{-1}$ and $W_0$ are respectively the lower and upper branches of the double-valued Lambert $W$ function). To evaluate $W_{-1}\left(\frac{-\alpha/e}{\alpha+1}\right)$ and $W_0\left(\frac{-\alpha/e}{\alpha+1}\right)$ numerically, see the "Numerical Evaluation" and "Software" sections of the wiki page.


What type(s) of gloves are effective against DCM and acetone?

Question: I know that standard latex and nitrile gloves don't stop common organic solvents such as DCM and acetone. However, I was reading a Reddit thread and there were comments that if you are coming into contact with solvents you are just wearing the wrong type of gloves. In a non-manufacturer specific fashion, what types of gloves will stop DCM and acetone? What will it slow down long enough for me to have a chance to finish what I'm doing and change my gloves in a safe manner? I am looking for a guide on what gloves to use. I just had DCM on my mind since nitrile doesn't slow it down, and it burns. And acetone, since it is hard to stop.
Comment: somebody did run a test on youtube: https://www.youtube.com/watch?v=TlJj0JLmLBI
Comment: There is a very common (and wrong) thought in this question: All or nothing, black and white etc. No glove made from any rubber will "stop" a solvent. Solvents (the smaller the molecule the faster) will diffuse through all rubbers, the diffusion rates may differ a bit, but not much. The problem to use some rubber or a different type is resistance of the rubber against swelling! Depending on polarity of rubber/solvent and degree of crosslinking, the rubbber will swell a little bit, or often so excessivelly, that it will tear from a touch.
Comment: If you're curious about solvent penetration through your gloves, I suggest pouring some solvent in to a glove, closing it at the top, and then seeing how long it takes to smell the solvent through the glove. Just be sure to waft carefully - some of the solvents will penetrate faster than you think!
Comment: When you try to find a suitable glove for acetone, don't ever let nitrile gloves come across your mind. Go and check for the permeation rate and breakthrough time in order to find the most suitable one, even neoprene gloves were not strong enough to prevent the breakthrough of nitrile.
Answer: I just did a bit of an experiment. My lab uses Kimberly Clark nitrile gloves, and we have a huge jug of acetone. First, I put a glove on my hand, and poured acetone all over it. My hand felt cold, but not nearly as cold as it feels when I spill acetone on my bare hand. I allowed the acetone to evaporate from the glove (approximately 30 s), and removed the glove. There was absolutely no acetone on my hand or the inside of the glove. I then took a fresh glove, and poured enough acetone into it to fill the fingers with acetone. I held the opening shut for about 5 minutes, and poured out the acetone. During that time, the glove slowly felt thinner and easier to stretch. At the end, it was so thin that it tore with almost no effort. So for the particular pair of nitrile gloves and acetone, it looks like somewhere between 1 and 5 minutes' exposure will render the glove useless.
Answer: You can use tips from the site link - the table at the bottom or just google which glove can suit your needs.
As you can read from the link:

Nitrile gloves are Low cost, excellent physical properties, dexterity, but they are Poor vs. benzene, methylene chloride, trichloroethylene, many ketones. They are recommended for Oils, greases, aliphatic chemicals, xylene, perchloroethylene, trichloroethane; fair vs. toluene,
According to Agronne for dealing with acetone you should use Natural Latex/Rubber or Butyl gloves.
For DCM there are no good gloves - you could try using neoprenes


How does one apply nutrient to a mead brew

Question: My wife discovered that the mead we are brewing smells a bit off, and a book we have on the topic suggest we may not have applied enough micronutrient. Any suggestions on getting more in? We have brewed for only a week and this is our first batch if that helps.
Comment: Probably better asked on the homebrewing SE site.
Comment: Does "smells a bit off" mean "smells like sulphur"?
Comment: @Escoce, the question was migrated here from Alcohol SE ;-)
Comment: Reuse dead yeast? Anyway, my guess is that it's more because of a lack of oxygen. It's not normal anymore to use open fermentation in home brewing and as a result the yeast is often suffocated.
Comment: @EricShain isn't this the homebrew SE site?
Answer: The most common nutrients for mead making, DAP and Fermaid-K or -O, come in powder form.  Adding a tsp of each to a 5-gallon batch of mead and mixing well is all it takes. If you see the nutrient doesn't dissolve well you can pre mix it with a little clean water (1/4cup) before adding it in.   A normal nutrient regimen is to add small amounts of nutrients (with mixing) on day 1, 3, and 5.  Then let it ferment along on its own.  Occasional mixing at day 10 or 13 will help to degas the mead.  Degassing the mead prevents dissolved CO2 from slowing the yeast. (Similar issue to the dude that left the comment about open vs. closed fermentation)
Comment: Ya know, that whole dissolved CO2 thing bothers me a bit. I haven't any issues with ferments being problematic due to dissolved CO2 buildup. For instance, I just racked my apple wine with an OG of 1.108 from primary which was never disturbed during primary, primary lasted about 10 days, the airlock was still slowly bubbling before racking and the finishing SG was .988. That happens often enough for me to think CO2 isn't part of a stuck ferment problem. Now I know this isn't mead which is a barren environment nutrient wise, but it does seem to indicate to me at least that CO2 isn't a problem.
Comment: I do agree about the nutrients, but I feel pollen is really the right nutrient for mead. DAP and Fermaid K produce metallic flavors and fermaid O doesn't have the nitrogen boost. Pollen provides tons of micronutrients without producing off flavors, in fact it probably improves flavor because pollen is rather fruity.
Answer: As a counterpoint, I've done mead batches with zero nutrients, and batches with different levels of nutrients, with success each time.  So far I've only used diammonium phosphate (DAP) and Wyeast yeast nutrient in the primary.  I've never done additional mixing, and I've never added nutrients partway through the primary, and only recently have I ever added more nutrients to the secondary (see other post). I start with what I start with, and I let the primary fermentation go until it's done and then some -- generally about a month at least.  The key is giving it time to do its thing.
Yes, sometimes things smell a little funny, as yeast with less nutrient than they like might produce some temporary off-notes in the nose.  A sulfury eggy smell is one such common odor.  However, after 30-odd batches, I've always found that these will age out, so long as you're patient.  And the thing about mead is, the longer it ages, the better it gets.  :)
In one extreme instance of bad smells (my first ever usage of Lalvin K1V-1116 yeast, and my first-ever Italian plum melomel with the plums in the primary), the smell was so sudden and so pervasive that my wife thought we had a gas leak in the house and she called the gas company.  Their engineer didn't find any methane leaks, but he did recognize the issue.  Even after such a funky start, the end product was blissfully divine.

If you do decide to add nutrients partway through the primary, mix it in well.  One important caveat I've heard about is that you might get a fizz-up: if the early mead is carbonated enough, adding nutrients may cause that carbonation to come out, so make sure you have enough headroom between the top of the liquid and the top of your container -- or you might wind up with a Mentos + Coca Cola kind of situation, and a huge sticky mess to clean up.


What is the difference between Electoral College and Electoral District?

Question: I've been writing a paper about Gerrymandering, but whilst reading about Electoral Districts, I started to wonder. Isn't it the same as the electoral Colleges?
Comment: You seem to be confused about what the Electoral College is. There is only one, it isn't "colleges". You might also be interested in [this question](https://politics.stackexchange.com/questions/11929/how-does-the-electoral-college-work-within-a-state).
Answer: The Electoral College is the body of 538 delegates representing the electoral points each State has. These delegates cast their votes in the general election for president and almost always vote the way their state voted. This is what was making the news following Trump's victory because many people were hoping delegates would change their vote to Clinton.
The Electoral Districts, also referred to as Congressional Districts, are the carved out subdivisions in each State that have representation in the House of Representatives. Gerrymandering is used to redraw the districts for various political and logistical reasons.
Comment: I would only add that "Electoral Districts" is a general term that refers to geographical divisions from which representatives to a multi-member political body at any level are elected, not just Congress. For example, state senate districts, state house districts, school board districts, and city council districts, for example, are also Electoral Districts.
Answer:
Isn't it the same as the electoral Colleges?

There is only one electoral college.  It is made up of electors.  There is one elector for each member of Congress plus three more for the District of Columbia.  So each state has two more electors than it has federal electoral districts.  That's a hundred three more electors in the college than federal electoral districts.
Gerrymandering can't affect the electoral college outside of Maine and Nebraska.  Most states award all their electors to the statewide plurality winner, so the district results don't matter.  Maine and Nebraska award two electors to the statewide winner (for the Senators) and one to the winner of each congressional district (for the House Representatives).  In 2008, Barack Obama won one elector in Nebraska.  In 2016, Donald Trump won one elector in Maine.
It's possible that redistricting had some impact, but it's not certain.  We'd have to know how it would have otherwise been redistricted.  There are many options, even if we know the basic approach.  For example, a minimal approach might shift just enough people from the higher population district to the lower population district.  But which people?  Basically any border region with approximately the right population would do.
When comparing, they often compare the new district to the old district.  But many times, the old district was no longer available, as population changes unbalanced the districts.  In some states, they may add or remove federal districts through apportionment.  Every ten years, the federal government takes a census and assigns each state how many House districts it gets.  Sometimes they stay the same (as in both Maine and Nebraska after the 2010 census).  Sometimes they change, either decreasing (Iowa after 2010) or increasing (Arizona).
Electoral districts can be used to refer to three different things.  First, it can refer to federal congressional districts.  Second, it can be used to refer to the districts for the lower chamber of the state legislature (or the only chamber in some states).  Third, the upper chamber can also be redistricted in those states that have two.  Any of these can be gerrymandered and the latter two control their own redistricting (in aggregate, not individually), possibly in concert with the governor.


Can I use Kerosene for lubing the cogs and the chain

Question: I recently went to a bike mechanic and he dropped some kerosene on the cog and chain for lubing them. He said that it keeps the dirt off and is quite volatile so will evaporate after sometime leaving some part behind which acts as a good lube. He said that he knows this by experience. Is it good to use kerosene as lubricant?
Comment: Worth adding that you really need not lube the cogs at all - just the chain.
Comment: People are really good at refining petroleum products nowadays, so that part that would get 'left behind' is exceedingly small. That said, kerosene (or some other distillate) is commonly used as a *solvent* to carry an actual lubricant into all the bits of the chain.
Answer: No, Kerosene won't leave behind enough of a layer to protect the chain.
It might be useful as a solvent to clean the chain before applying a proper lubricant.
Comment: I would add that kerosene acts just like WD40, so is like a big no.
Comment: I'd also only use it if I was going to apply another wax or dry lubricant.
Answer: Kerosene is good as a cleaner for your chain, but never as a lubricant. In fact, kerosene will clean all the lubricant remaining, increasing friction.
Answer: Kerosene is technically a paraffin which comes from the greek word wax.
Kerosene is used as a fuel and a solvent.
A waxy solid extracted from petroleum is called paraffin wax.
Pouring a liquid kerosene on a chain is not going to leave much if any waxy lubricant behind.
Kerosene is not a good choice as a solvent as it is flammable.
http://en.wikipedia.org/wiki/Wax
Answer: It would only be effective if the chain was wet lubed, and clean. As a solvent Kerosene thin and redistributed the lubricant already on the chain. It will therefore have an effect at lubricating the chain as the pressure points will get lube migrating to them, provided small enough amounts were use that the lubricant was not washed off the chain.
Using kero this way would be better than not lubing the chain, however it would be better to use a lube and do it properly. Where I might use it is a chain that has been lubed then stored for a while to get things moving again - but in all cases it has no benefit over using a proper lube as a lubricant.
Answer: There is actually very little value in lubricating the chain, all you really need is to keep it clean and rust free. Kerosene seems about as good as anything for doing that. The primary reason to lubricate a chain is to keep water out of the rollers and just generally keep the chain rust free.
Most of the things people put on chains actually shorten the life of the gears by attracting dirt and dust. This grit combines with the grease to create a grinding paste that can wear gears in a relatively short time.
But how you take care of your bike chain is one of the great religious debates in the cycling world, everybody has a theory. For just about any grease/oil/wax out there you'll find somebody that swears by it as a bike chain lube.
Lube or don't lube, use the magic wonder fluid, all that really matters is that you check your chain for wear at regular intervals and replace it when it starts to show any signs of wear. Compared to all the other parts on your bike, chains are cheap, replace them often and your expensive cassettes and chainwheels will last a very long time.
Answer: Kerosene is not a good lubricant, but it's good for dissolving the greaser in a chain, and has long been used for cleaning chains. (Gasoline can also be used, but poses some safety issues!)
In the UK, kerosene is called paraffin, so British bike maitenance books recommend cleaning the chain in paraffin. In the US, "paraffin" means candle wax. I suspect the curious trend of washing a bicycle chain in hot wax comes from this transatlantic mistranslation.


Can we shoot normal pictures using a macro lens?

Question: I am confused about macro lenses (or micro as Nikon calls them). Can we shoot normal (Nature) scenes using the macro lens?
Comment: possible duplicate of [What's the difference between a regular lens and a macro lens?](http://photo.stackexchange.com/questions/10569/whats-the-difference-between-a-regular-lens-and-a-macro-lens)
Answer: Yes.
Macro lenses can be used on subjects at more normal distances.  They are not just for close up objects.  You can shoot portraits with the 60mm or 105mm Micro for example, as those are good focal lengths for portraits.
Macro lenses are generally very sharp, but bokeh may not be as nice as a standard lens.
Comment: There are, though, a few notable exceptions. Both Canon (the 65mm MP-E f/2.8 macro) and Minolta (AF 3x-1x f/1.7-2.8 Macro, no longer beng produced under Sony) have dedicated macro-only lenses that will not focus further away than 1:1, and most of the bellows macro lenses from the manual focus days are mechanically prevented (by the bellows) from getting close enough to the sensor for infinity focus. But they are exceptions, and their macro **only** nature is almost always pointed out in catalogs, etc.
Comment: I was with you right until when you said macro lens don't have good bokeh.
Comment: great....this helped indeed
Answer: Macro lenses are optimized for close-up photography and small f-stops (because depth of field is reduced the closer you get to a subject, so small f-stops (larger numbers) are usually required). They will focus closer than non-macro lenses. They work quite well for everyday photography, too. However, they are usually not "fast" lenses, quite often around f4. So, you won't be able to get the "subject-in-focus-and-background-totally-blurred" image as easily than if you had a fast f1.7 or f1.4 lens. But if you move close to an object, because your depth of field is reduced, you can still get this effect, even at f4.
Comment: There are plenty of fast macro lenses.  Sigma has a 105mm, 150mm and a 180mm f/2.8 Macro.  Fast glass is actually important for macro as you need shallow depth of field to just select you target and because of how close you are to the subject you need more help getting light.  (Nikon has a 40mm, 45mm, 55mm, 60mm, 85mm, 105mm that are all f/2.8.)
Comment: Hmm. I guess I have to disagree about **needing** shallow depth of field for macro. You get it whether you like it or not, and the faster macro lenses do not, in my opinion, help macro photography with the lenses. It helps the use of the lens for non-macro photography, though.
Comment: Matthew Whited couldn't not be more wrong if he tried. I have never missed faster then F2.8 for macro, actually I do not EVER use anything near F2.8 for macro, I work in the F11-F32 range almost exclusively. I do use the macro lenses F2.8 for portrait use, but then again it's not maco work is it.
Comment: Depends on what you are trying to do.  I want shallow depth of field on macro and with small insects and such it's nice because it allows you to easily blur the background and shoot handheld and without a flash.  Most of my macro is either 200mm at f/2.8 or 400mm at f/5.6.


Did Existenz influence Inception?

Question: The movie eXistenZ, which stars Jude Law, shares the concept of layered realities with the movie Inception. Was the movie Inception influenced by Existenz's concept at all?
Comment: Excellent question and I'm happy someone remembers Existenz. But I fear, this can be answered only by Christopher Nolan.
Comment: [Paprika](http://www.imdb.com/title/tt0851578/) is also said to be an influence for inception.
Comment: Paprika *must* have been an influence; there's too much similar, plus that movie would have come out around when Nolan would have been dusting off the Inception script for revisions. Too much serendipity, there, I say.
Answer: As Mnementh points out, it's probably impossible to say with certainty until he joins the site, but it seems as though he hasn't explicitly made mention of it yet. He has said that:

"The whole concept of avatars and living life as someone else, there's a relationship to what we're doing, but I think when I first started trying to make this film happen it was very much pulled from that era of movies where you had 'The Matrix,' you had 'Dark City,' you had 'The Thirteenth Floor' and, to a certain extent, you had 'Memento' too. They were based in the principles that the world around you might not be real."

source
The Matrix was 1999; Dark City 1998; Thirteenth Floor 1999; Memento 2000, so eXistenZ (1999) falls neatly in that "era of movies" he talks about. It's conceivable that it was an influence along with the ones he mentioned, but him not explicitly bringing it up leads me to believe it was not, or at least not a major one. He hadn't seen Last Year at Marienbad (1961) to which Inception also drew a lot of comparison.
I tend to think that the dream/reality layers idea is not that original or uncommon and that there are plenty of previous works that build on it without necessarily being an influence on those which follow. For instance the Scrooge McDuck comic people said Inception ripped off.
All speculation of course :)
Answer: The concept of layered realities does seem very similar. Take for example the following scenes.
In the scene below, the viewers of the movie already think they are within the game (1 layer deep) and are going to boot into a next layer. This can be seen as similar to when Cobb and others were in the van about to jump again. So in both cases, the viewer needs to keep track of where reality in the movie starts and where the new layer of reality begins.

Images are used for the critique of Existenz
Here we have the first possible jump and once the viewers reach the end they begin to question whether this was indeed the first pod entry. This is similar to questioning whether Cobb was already a layer deep before booting in on the airplane.

Images are used for the critique of Existenz
Here is where it gets tricky, let's call this the jump into limbo. In Existenz, only one character actually uses the pod. So did that character go one more layer deep or did both characters jump back up a layer? This can be compared to the snow mountains layer to the jump to Fischer's layer and finally to limbo. No one is sure that Cobb did indeed escape limbo for the whole show. That is, Cobb could have been in limbo for the entire show.

Images are used for the critique of Existenz
The next feature that can be compared is the idea of a kick, where in Existenz it is shown as a pause of game whereas in Inception the user supposed thrown up a level/layer.
The final item is that of the user/gamer imparting their own images/thoughts into the game. That weird gun that was used in the opening is shown in the later layers. So this most likely means that the game uses the thoughts of a person to advance the dynamic play. Thus it shows the same psychotic effect as in Inception because the player will need some sort of "totem" to hold on to what they believe to be reality.
I believe the idea of layering (questioning the present reality) predates both of these films such that both of these movies could have gotten influence from earlier books/scripts/movies. Though the similarity between films is quite remarkable.
Comment: The concept of the players bringing their own ideas into the game is also mentioned at the end, when *Yevgeny Nourish* is worried about the heavy anti-game attitude *inside* the game and wonders if that was brought in by one of the players (apparently by *Allegra* and *Ted* (if those actually were their names in the real world (or the highest level the movie ends at, so to say), too)).

Did Existenz influence Inception?


Making sourdough bread in a warm and humid climate

Question: I live in a warm and humid climate - average temp is mid 80's.  I have been making sourdough and like the flavor, but the loaves are flat, very dense texture and crunchy crust.  Even when I bake in a bread pan the loaves don't rise much.  I use whole wheat WW in the starter and equal parts of white and WW in the bread.  Starter is working nicely and quickly, about 3 hours to double/triple in size.  Am thinking that I need to start using some yeast, but would like to bake acceptable loaf without it.  Any thoughts would be appreciated.
Thanks, Mike
Comment: It sounds like you have a good active starter, so if I had to guess I'd say your dough is too dry, preventing a good rise. Without a recipe or knowing your method I wouldn't attempt an actual answer.
Answer: If your starter is tripling in 3 hours, it's unlikely that you need to add additional yeast.
If the humidity is causing your dough to spread as it rises, you could try slightly lowering your hydration to account for moisture in the air. You could also add a fold in your bulk ferment time to give more gluten strength.
You don't mention how long you are proofing your loaves, which could be very important. Generally sourdough will need several hours at a moderate temperature to rise properly. Be sure you aren't rushing to the oven. (When you poke a loaf, it will gently and slowly spring back when it's ready.) This may mean that you will need to proof in the refrigerator, basement, etc to keep your loaves cool as they proof.
Finally, if spreading continues to be a problem, adding some vitamin C powder (ascorbic acid) can help get more volume in your loaves. This works by making the gluten tighter, so use it sparingly. It is especially beneficial in whole grain sourdoughs.
Comment: Thanks for the quick reply.  I'm making another attempt tomorrow and will head your advice, especially about the proofing time.  That's a tough call for me at times.  I'll also take another look at the hydration issue, now that you mention it, the dough does seem to get "wetter" as it proofs.
Comment: If the dough is getting wetter as it proofs, it can help immensely to just dust it lightly with flour and give it a gentle fold a few times during proofing. I've actually seen great artisan bread made with this method using entirely kamut flour, which is very low in gluten.
Comment: Ascorbic acid? I haven't tried that before, I do get some spreading when I use much whole grain, and some vitamin C cannot hurt :D Anyway, folding is great way to make the bread firmer. I fold 3-4 times on my sourdough and it firms up for each time I fold.
Comment: @daramarak Yeah, generally most spreading can be fixed through folding. The vitamin C is just sort of insurance for when you're not sure.
Answer: It's almost impossible to diagnose your baking problem without knowing your recipe, method, and skill level, but I'm going to have a swing at it anyway! :)
First, make sure you're using the right kind of flour. Do not use whole wheat pastry flour, bleached flour, or cake flour. These will all cause problems. You'll want to use good, *unbleached *all purpose or whole wheat flour with a protein content around 12-14% (check the label -- 3 or 4 grams of protein per 30 grams of flour). Even better: check the ingredients for hard red winter wheat. Don't use anything that says soft wheat.
Second, unless you're confident in your recipe (i.e., you've made it before successfully), I would recommend sticking with white flour at first. It's much more forgiving than whole wheat, and once you gain confidence, you can start to substitute whole wheat a half cup at a time.
Third, really keep an eye on things during the proofing stage. When I make sourdough bread, it takes about 2-2.5 hours at 65-75 degrees. If your house is 85 degrees, you may need to reduce this to 1-1.5 hours. Or, like sourd'oh suggested, proof in the refrigerator. In fact, I've had great success with doing the final proofing overnight in the fridge. I don't even let it warm up when I bake it -- just throw it straight into a hot oven!
Finally, if the recipe you're currently using continues to give you trouble, try another one! My favorite resource when I was learning to bake was The Fresh Loaf forums. In fact, there's a reliable whole-wheat sourdough recipe there that you might want to compare to your own. There are also a number of excellent modern baking books to consider, including Peter Reinhart's Artisan Bread Every Day.
Best of luck baking!
Comment: Thanks for the feedback and insights. As you may have guessed, I'm not too sure of my recipe and am seeking the right one.  I was baking break regularly a few years ago, using the basic recipe from " the Tassajara Bread Book", and am just coming back to making sourdough.  The bread never did rise to my satisfaction, whichiismwhy I'm
Comment: Sorry, hit the send button by mistake.  To continue, I'm trying new recipes.  Another question, should the dough be kneaded much, or at all, before the second rising and shaping into loaves, or gently shaped and placed on baking sheet or pan?  Thanks again, Mike
Comment: The protein content and red wheat are not at all necessary for high rise. Many countries never use them and make bread with low protein flour, bread flour is a North American thing. You have to use them if you want the typical high-gluten texture, but they won't help with bread which doesn't rise.
Comment: User23445, you should treat the dough very gently before shaping. Kneading at this point is unnecessary, because the gluten structure has already been developed.

I think Rumtscho may be right about protein content. You _can_ use cake flour or pastry flour, but higher protein flours are easy to come by and will give you the results you want.


UBUNTU::Lamp::I develop websites on lamp, which UBUNTU version i need for develop, desktop or server ubuntu?

Question: UBUNTU::Lamp::I develop websites on lamp, which UBUNTU version i need for develop, desktop or server ubuntu?
Thanks,
Yosef
Answer: You would deploy the server version for production, but if you plan to use the X11 gui to work on, you would need the desktop version. Otherwise the server version is sufficient.
In reality, the only real difference between the two is the default package selection. You can convert the server version into the desktop variant with a single command if you like.
Comment: I would very much like to know that single command, so I can show off my CLI-FU :)
Comment: `apt-get install ubuntu-desktop` (or `kubuntu-desktop` or `xubuntu-desktop`). It's a meta-package that pulls in everything needed for the desktop.
Answer: Either Desktop or Server (or Netbook, if you like). As SvenW points out then only real difference is the default package selections (server has no X by default, netbook defaults to a different desktop config optimised for small screens) - you well find that the default Apache, MySQL and PHP setups will be identical on all the different Ubuntu variants.
Where you will find differences is between releases. For instance Ubuntu 10.04 carries PHP version 5.3.2, Ubuntu 9.10 has PHP 5.2.10 and so on. If you are developing generally then you probably just want to go with the latest. If you are working code for a specific deployment then you might want to try get exactly the same package versions that will be used on that deployment - that way you are developing and testing on exactly the same environment as the final deployment will be using. On that point you might want to use the same Linux variant (which may not be Ubuntu) as the client, either directly or in a VM, for testing purposes then you are as close as you can be to exactly replicating the environment the code will eventually be deployed in.
Answer: Not strictly true, as the server and desktop kernels are different and that command won't upgrade the desktop kernel.


How can I get a sharp image of my cat against a white background with basic equipment?

Question: I am a complete beginner and wish to photograph my cats on plain white backgrounds with the cat appearing very crisp and detailed.  Can anyone tell me how to achieve this without buying lots of expensive equipment please?
Comment: There are many questions and answers here about shooting against a white background with various subjects and how it can be best achieved.
Answer: A beginner level DSLR with a kit lens would be enough for this use case. Taking into consideration you're a complete beginner, you probably can just use auto-mode for this task. If you are wanting to get into photography seriously or just really need a super crisp image I would suggest buying a prime lens (maybe a 50mm).
Comment: @gazey - What Cody says plus consider spending some time reading or exploring what different type of light (diffused, direct, sun, on-camera flash) and different focal length (blurry vs sharp background, subject isolation, shape distortion) do to your cat pictures.
Answer: It doesn't require buying a lot of expensive gear, but it does require buying gear.  And you don't need a dSLR, you need a lighting setup.  And going into studio-style lighting setups requires a bit of experience and knowledge.  This might be a look you can achieve without lighting, but it's unlikely.
The white background and crisp clean look are generally done by lighting the background and the subject separately.  So you need at least two lights, but probably three.  You need some way to trigger them. You need the backdrop.  You need enough physical separation and control of the light spill so that they're completely separate areas of light.  The background is essentially overexposed enough to be white relative to the subject in-camera.
So you'll probably need to master off-camera flash, which in turn is easier to do if you're mastered M mode on your camera, which in turn is easier if your camera has an M mode and a flash hotshoe.
For more details on the lighting set up specifics, see also: Zack Arias's white seamless tutorial, part 1 and part 2 on Youtube.


Optimal Win Rate Standard Deviation

Question: I've been tracking my live sessions for some time now.  After 35 sessions (about four hours a session) my win rate is 34.42 an hour.  My win rate standard deviation is 157.67.  This seems high to me.  I play pretty TAG at the 1/2 NL game.  Is this high standard deviation just an expression of the volatility of low limit cash games, or is this my problem?
Comment: It's been brought to my attention that you haven't denoted what measurable unit your win-rate and StDev figures represent. e.g. Are they in $USD/100 hands or bb/100 hands? If you could update it, that would be great, otherwise i'll just assume you meant bb and do it soon myself. Thanks.
Answer: Typically, live play will mean you're seeing between 30-50 hands per hour. In your case, this will mean that you've seen somewhere in the region of 7,000 hands. This is an incredibly low number to make any significant, reliable assumptions about the StDev of your win-rate. The data set simply isn't large enough to be approaching what we'd consider a normal distribution yet.
As for your question, <code>"Is this high standard deviation just an expression of the volatility of low limit cash games, or is this my problem?"</code>...It's just too early to tell!
Commonly...

6max, your StDev will be about ~90bb/100 hands.
FullRing, your StDev will be about ~80/100 hands.

Check out this post for some helpful Statistical Tools for analysis of your game.
Comment: Fair enough.  About how many hands would you say is a good sample size?
Comment: The money won per hour was actually the stat I gave in the question.
Comment: Not to put you off but we're talking 100,000's to truly feel comfortable with the StDev volatility measure. It's not impossible to gain insight into your game using this stat, but it's genuinely difficult as the games change periodically. Thus one sample of hands and the corresponding StDev represent more of a snapshot in time, rather than a linear progression of an attribute of skill.
Comment: 100,000s was really easy back in the day with online poker.  At a live game it's going to take me playing full time for a year.  One final question, when playing in a live game how do you determine your bb/100 stat? Do you just estimate the amount of hands you played?
Comment: Yes, other than actually counting the hands you could do that. Also, consider determining your profitability in a game by Money Won Per Hour (or $Won/Hr). I find this a useful measure alongside bb win-rate to gauge my success.
Comment: OOPS! ;D Ignore the second part of my comment.
Comment: lol, will do that.
Answer: Disclaimer:  All of what follows applies only to winning players.  For non-winning players, none of this matters a whit.
I'm not going to discuss actual, hard numbers as most people familiar with StdDev in poker will declare something that can be interpreted as "StdDev is completely useless until you have 100k+ hands," -- a sentiment I disagree with in principle.  You can gain some insight with far fewer hands.
What I'll discuss is the relevance of StdDev in poker.  So, what does StdDev tell you about your game?  StdDev is an indicator of your variance.  Your variance, in turn, is effected by many things.  Two of the most important are:

Your skill relative to your opponents
Your long-run winrate at a given stake/structure.

As your skill increases relative to your opponents, you'll win more.  As you win more, your long-run winrate increases.  Simple.  As your winrate increases, your variance decreases.  The best .05/.10 player in the world might have a huge winrate measured in tens of BB/100 online, and a very low variance.
But skilled players tend to move up in stakes.  As you get better at poker and move up in stakes, you'll find that your skill relative to your opponents  actually decreases.  You may still have an edge, but your edge will be smaller.  This will reduce your winrate, thereby increasing your variance and your StdDev.
That is not to say that when your StdDev is high you need to work on your game.  I mean, yes -- you need to work on your game, all the time, but it has nothing to do with your StdDev.  The best online $25.00/$50.00 player in the world is probably going to have a long-term winrate that is much lower, probably measured in the low single digits in terms of BB/100.  They have an edge, but their edge is smaller.  So their variance and StdDev are going to be higher than the world's best $0.05/$0.10 player.  Does that mean that the .05.10 player is better than the 25/50 player?  Hardly.
Variance is also dependant on your game style.  Set-mining nits will have a lower variance than a loose-aggressive player.  That also doesn't mean that the set-miner is better than the LAG.  Nor does it mean the opposite.
In other words, StdDev has no direct relation to your absolute skill at poker.  Other variables do.  StdDev only has an indirect (at best) relation to your skill.
My advice is to forget about StdDev as a diagnostic tool, and look at it as a mathematical curiosity.
Answer: 35 sessions at 4 hours each is only 140 hours. That's a fairly small sample size to me. Which means your standard deviation could easily be "high" (or low).
The other issue is that it's low limit, $1/$2. As such, you'll get a wider range of outcomes than at higher stakes, because this represents "play money" to most people.
It's not really a "problem" as far as you're concerned. Most people would be glad to be doing as well as you.
Comment: Ha.  I suppose problem is the wrong word.

Optimal Win Rate Standard Deviation


Air conditioning unit sitting on the ground

Question: We've lived in our house 11 years.  Our air conditioning (condenser) unit, the big boxy thing sitting outside, is not sitting on a concrete slab.  It's just sitting on the ground and we noticed this spring that water was pooling and it was actually sitting in several inches of water.  Them more I think about it, the angrier I get that the inspector didn't catch this 11 years ago.  I've read that mounting it on the house is the best solution but that's not an option.  What do I need to do (get a concrete slab poured for it to sit on and check yearly that it's level?) and who do I call to help (an electrician?) I obviously don't know what I'm doing so any help is appreciated.
Comment: They make pads out of plastic and concrete, that are designed for condensing units to sit on.  You might be able to lift the unit just enough, so you could slip one under it.  It might not lift it out of the puddle, but it might allow you to keep it level.
Comment: Have you looked up the manufacturer's installation instructions?
Answer: Code requires outdoor condensers be installed on a reasonably level surface raised at least 3 inches above ground level.  If water pools in the lower part of the unit during cold weather and then freezes, the condenser coils can be damaged by ice expansion and that will often end the life of the unit, although the outdoor condenser can sometimes be replaced.
As Tester101 said, there are prefab pads made for this and if you can raise your unit without damaging any lines that are connected then you may be able to do this without an A/C technician.  Great care must be taken not to kink or break the refrigerant lines if you attempt this.  Otherwise, you will need an A/C contractor to recover the old refrigerant and disconnect and temporarily cap the lines; and then after you install an acceptable pad the A/C contractor will need to install a new refrigerant dryer, reconnect the lines, purge the lines with nitrogen, evacuate the system to a deep vacuum, and correctly recharge the system with new refrigerant.  If everything goes well this is around a half-day of work (not including installation of a new pad).
By Request:
2009 Uniform Mechanical Code 1106.2 "Supports and Anchorage" last paragraph:

A compressor or portion of a condensing unit supported from the ground
  shall rest on a concrete or other approved base extending not less
  than three (3) inches (76mm) above the adjoining ground level.

Admittedly, this language does not use the phrase "reasonably level" and it is not the most current version.
Comment: Also, certain states, have "hurricane" provisions requiring 'concrete' slabs.


How are cathode rays produced?

Question: Why cathode rays are produced if pressure of the gas discharge tube is lowered to about $10^{-4}$ atm?
How bombardment of glass of gas discharge tube from cathode ray result in a faint glow?
Answer: "Cathode rays" are simply beams of electrons. The name exists because cathode ray devices predate the discovery of the electron. The sharp shadows produced by Crookes tubes meant that something was travelling in a straight line from the cathode down the tube, so they were named cathode rays.
The vacuum doesn't have much to do with the production of electrons, per se, but without high vacuum, the electrons collide with gas particles before they travel very far. If there's enough gas, you get a plasma rather than a beam of electrons. The electron beam is produced by thermionic emission in hot cathodes—electrons are liberated from a hot filament when the thermal energy is enough for electrons to exceed the filament's work function. In cold cathodes, electrons are released by field emission, where a large applied electric field allows electrons to tunnel away from a metal electrode.
The glow of the glass envelope is luminescence—either fluorescence or phosphorescence (or both). Basically, the electrons striking the glass excite components of the glass to an elevated electronic state which releases light upon returning to the ground state. Normal glass isn't particularly luminescent so tubes designed to produce light (like a CRT) are coated with phosphors.
Answer: When a high voltage is applied to the tube the electric field accelerates the small number of electrically charged ions always present in the gas created by natural phenomena called photo-ionization and radioactivity.
These collide with other gas molecules knocking electrons off them and creating more positive ions in a chain reaction called Townsend discharge. All the positive ions are attracted to the cathode. When they strike it they knock large numbers of electrons out of the surface of the metal which in turn are repelled by the cathode and attracted to the anode. These are cathode rays.
Answer: When electric current passes through the gas inside the tube which is at low pressure, then the electric current manages to overcome the force between the electron and the nucleus and the the free electrons forms a ray which travels towards the anode in a straight line.
Answer: Cathode rays are so named because they are emitted by the negative electrode, or cathode, in a vacuum tube, also called as a cathode ray tube.
Cathode rays are just a beam of electron observed in vaccum tube. when the dicharge tube or evacuated glass tube is facilitated with 2 electrode and with high voltage, due to emmission of electron from and travelling in perpendicular to cathode,glass opposite of negative electrode(ie cathode) is observed to glow.
High electrical potential is applied between anode and cathode to ionise the residual gas in the tube. the ions are accelerated by electric field and collide with cathode which released electrons. As electrons are -vely charged they are repeled by cathode and are attracted bty anode.

Crookes tube is a rarefied tube evacuated to a pressure below 10−6 atm. It was used in discovery of cathode rays.
Source
Wiki
Link
Video
Answer: At low pressure ($10^{-2}$ atm) and higher voltage (10000 V) gases are partially ionised in the discharge tube. Positive ions of gases strike on the cathode. Due to the thermal effect, a beam of electrons releases from the surface of the cathode. This is called a cathode ray.
Answer: Cathode rays are originating from cathode as cathode is negatively charged. These rays then hit the gas sample inside the tube and ionize it. The electrons ejected from the ionisation of the gas travel towards anode. These rays are actually electrons produced from the ionisation of the gas inside the tube.
Comment: This addresses the second question, but not the first.
Answer: Cathode rays are the streams of fast moving negatively charged particles originated from the cathode.
At the pressure of 1 mm Hg in the tube, the positive column breaks into alternate and dark dics, then the cathode leaves the glow, this is cathode rays.

How are cathode rays produced?


What happens with WHO IS privacy protection when the domain is not active?

Question: I'm running small Wordpress site (about 15k visitors per month) and I want to buy a custom domain and monetize it. During the registration I'm asked for personal info, I know I have to provide it. I also want to buy WHO IS privacy protection, but I have a question - it's for one year, the domain is too. What happens if I won't pay for my domain after one year - will all my personal information be visible, or will it dissapear cause the domain is no longer active?
Thanks for your answers.
Comment: When the domain expires, you no longer own it. If the domain expires along with the privacy registration, it may be possible that for the short redemption period that personal information can be seen. I am not sure. This is a very good question! Cheers!!
Comment: Thanks for your answer, closetnoc! I think i will register my domain even today!
Comment: @closetnoc Would you like to add this as an answer? Just found this Q in the unanswered list :)
Answer: The short answer is that it depends on how you chose to protect your privacy. Terms vary by Registrar and by extension. For example, .je domains never reveal anything more than the Registrant's name regardless of the seller's policy - it is a decision made by the Registry managing the extension.
The TL;DR is "Choose the TLD and  Registrar wisely".
If you purchased a third-party WHOIS protection service (note it's spelled as one word, all caps, 'WHOIS' as per RFC 3912) then the provider's terms govern that separate purchase, which is a different transaction from the domain name purchase. There are multiple WHOIS proxy/anonymity providers and you need to check the specific Terms for each to learn the answer.
One thing to watch out for with this arrangement is that you are typically registering the domain by proxy. You are not the domain owner, the proxy service owns the domain. As an example, here is GoDaddy's Terms & Conditions page which makes this clear. They own the domain, you pay the middle-man proxy to purchase and administer it. There are legal implications to this that you should talk to a lawyer about if you are serious about monetizing the domain.
Another approach which gives you more rights and control is to choose a Registrar that provides anonymity service as standard and by default. It's all one transaction, no third-party involvement or extra purchase to make. One I use and recommend is Gandi.net (no affiliation, just a customer) and they protect your data and never sell it by default. You are the Registrant and you directly own the domain, the Gandi privacy scheme is not a proxy service.


Car battery won't charge

Question: So I've come back from uni and my dad flattened the battery in the car (a new battery) and was recharging it back up. It was reading nearly full on the charger and I needed to go out so we unplugged it. The car wouldn't start. We plugged the charger back in and it super low charge again. We then tried to jump the car using a brand new battery and it wouldn't start it. Not really sure at this point what to do or what is wrong with it. Any help or suggestions would be greatly appreciated.
Comment: After the battery say sat for an hour what's the charge on it, anything below 10.50 then you got a bad cell in it, the next time you get a battery make sure you prime it, the batteries sit on the shelf in the store and all the electrolyte solution sinks to the bottom of the battery, leaving the upper half of the cells vulnerable to high heat, potential to blow a cell early, so it helps to tilt it and shake it slightly to stir up the solution again
Comment: You also may have a short in your electrical system, turn off the car and use a mutimeter on all the fuses, nothing should be using any voltage
Comment: Does the dash lights appear? When do you try to start the car do you hear the engine cranking?
Comment: Yes the lights come on and the radio etc. but the engine cranks a little and then gives up
Comment: When we plugged the charger back in it was reading around 13
Answer: The 13 is irrelevant here!  Watch the voltage when you crank over-it will drop
This figure should not be less than around 10v -if it is, then the battery has no amp power to start the car and is defective, even if new

Car battery won’t charge


Placing a featured image into header

Question:
How can I place featured images into the header, so each post has
it's featured image within the main header?
Also on category archive pages and the main news page, the featured
images are being used in the traditional way, using the custom post
image so is there a way around that too, where I can use the
featured image for both posts and header.
Maybe there is a way of having two custom thumbnail images and
calling one up for the featured image and the other for the header?
Answer: Your question is confusing but I'll try.
Item 1
The $post variable is set before the template loads. It is preset to the first post in the Loop by the main query, so on single post/pages it matches the post/page that you are on and you can use it in the header to display your thumbnail.
Item 2
This is the most confusing of your questions. I am not really sure what you want. Again, the $post variable is set before the template loads. You could use that to display the thumbnail from the first post in the results in the header of the page. You would be using "the featured image for both posts and header" but there are potentially multiple thumbnails on a category archive so I am not sure that is what your really want.
Item 3
By default, there is not way to do this, but it pretty easy to have multiple featured images by way of custom meta fields.
See also: https://wordpress.stackexchange.com/a/109468/21376 A synopsis of that link: Trusting $post out of Loop context is a bit dicey unless you really understand WordPress template rendering internals. Using a function called get_queried_object can help get more expected behavior.
Comment: Thanks for having a go at answering my question, if you have a look at the HTML5Boilerplate-Starkers-WordPress-Theme on github http://bit.ly/19akA4B it answers my problems and probably explains what I was on about.

Placing a featured image into header


What is it called when singers very rapidly change pitch while singing the same syllable of text?

Question: I have been wondering whether there is a term for the technique singers use when they sing one syllable of text over a large number of different notes very quickly. There are examples of this in Händel's operas. Since this technique is used within a syllable and there are no consonants available to separate the notes from each other, it often sounds as though the singer is singing an 'h' to facilitate the separation of pitches.
Answer: This answer actually has two parts:
Melisma is when a vocalist sings multiple pitches on one syllable. When you hear music in this way, you would say that the music is melismatic.
Coloratura is a "coloring" of musical figuration meant to embellish the musical line. In Handel's time, much of the embellishing was improvised over the written line.  It also concerns how the melisma is used in the music.
Comment: Very semantic question, but:  would you lump in grace notes in jazz, trills in Irish music, register "cracking" in pop/country, etc etc into "coloratura"?  And further:  in pop music, would you describe as "melismatic" the style of a vocalist who is prone to this (I am thinking, for example, of Ian Anderson of Jethro Tull)?
Comment: Actually, not a semantic question. To answer your question, yes I would.  See my comment to Wheat Williams' answer below for why.
Comment: I'm afraid the sort of vocal decoration pop singers revel in - "I will always love you-u-u-u-u-u-u-u-u-u-u-u-u" are difficult not to class as coloratura.   And classical composers' discomfort at sopranos who insisted in inserting such embellishments when NOT written is well documented!
Comment: Sorry, still not clear.  I may not be understanding the original question, but several examples come to mind of what I imagine being asked by OP: Vien Con Nuova Orribil Guerra (La Statira, by Albinoni), and the voice play on "guerra" throughout.  Also, Alleluia (from Exultate Jubilate motet K165 Mozart), the voice plays on some prolonged "a" syllables from "alleluia" which is sung throughout.  Here, it is written in music with many notes, one syllable - so not coloratura by definition.  Is this example of "melisma"?
Answer: I would like to expand on @jjmusicnotes' answer.
When a number of notes for one syllable are written out in the sheet music by the composer, the term used to describe this is melisma.
When the performer chooses to add additional notes in an improvisational manner (notes which are not written out by the composer), the usual term for this is ornamentation. Ornamentation is a common element of music from the Baroque period, such as that by Handel and Bach, and certain kinds of ornamentation are used by singers and solo instrumentalists alike.
The term coloratura is not often used in this context; rather, the term "coloratura" is usually used to describe a soprano singer with an unusually high range of notes who is often found singing music with a lot of melisma or ornamentation in it.
The adjective form of melisma is melismatic. From the academic standpoint, you often hear the term "melismatic" also used to describe the florid style of singing found in American R&B music by female singers such as Whitney Houston or Mariah Carey, who are known to sing a lot of melodic notes on a syllable. So the melismatic style is found in other places besides Western classical music.
Comment: Thanks for the expansion Wheat, a couple things though: music does *not* need to be written down in order to be considered melismatic. If there's more than one pitch on a syllable, it's a melisma. Regarding "coloratura" you are actually mistaken, the **textbook definition** of "coloratura" is: *florid vocal ornamentation*. Sopranos were called thus because they were divas and always colored passages unnecessarily, preferring to hear themselves more than other people. They received the most attention, so people wanted to be like them, and the term was designated to the performer.
Comment: Thank you, @jjmusicnotes. I'm actually unfamiliar with the use of the term "coloratura" as you found in your textbook. I stand corrected.
Comment: No worries, the text to which I referred is a recent text on the history of western music compiled by Music History professors from Indiana University, and is well-regarded in the field of music.
Answer: Those are called coloratura.  There is even a voice category "coloratura soprano" named after them.


GUDID / Device Registration Common Data Element

Question: Is there a field or data element common to both the UID and the device registration databases in FDA?  I'm trying to tie the two together but can't seem to find a common field.
Answer: Unfortunately, the UDI and Device Registration endpoints do not have a common field that could unambiguously identify a device between the two.
Comment: Thank you.  I have found that the "proprietary name" in FDA and either "brand name" or "device description" do match up somewhat, but like you said, it's not necessarily unambiguous.


UIScrollView callbacks while animating internally

Question: I have UIScrollView with one child that is zoomed (returned in viewForZoomingInScrollView:scrollView) and a number of other children which annotate the zoomed view and should always be positioned on top of the zoomed view at relative coordinates
<code>UIScrollView
    - zoomChild (size 100x100 at scale 1)
    - Annotate Child (size 10x10), always placed at relative position (0.2, 0.2) of zoomChild's frame
</code>
I've subclassed UIScrollView and overridden scrollViewDidZoom:. I position an annotation child like
<code>- (void)scrollViewDidZoom:(UIScrollView *)scrollView
{
    self.annotateChild.frame = CGRectMake(0.2*100*self.zoomScale, 0.2*100*self.zoomScale, 10, 10);
}
</code>
This works fine as long as the user is interacting with the scrollview. scrollViewDidZoom:/scrollViewDidScroll:, however, seems not to be called when

zoomBounce: scrollview is pinched smaller than minZoom, user releases his finger and scrollview animates back to minScale. scrollViewDidZoom: is called when the animation is complete, but not during.
When zooming to a rect using zoomToRect:animated:. Again, scrollViewDidZoom: is not called until animation has completed.

So the question boils down to: how can I get notified whenever self.zoomScale changes, including when this happens via some internal animation?
Alternatively, can I add my annotation views as subviews to the zoomView and somehow make sure that they are not scaled?
Answer: Here is an answer that might work: In iOS 4.0, why does UIScrollView zoomToRect:animated: not trigger the scrollViewDidScroll or scrollViewDidZoom delegates while animating?
I need to do the same as you, but I didn't get to try it out yet.


VMWare Server replacement?

Question: Now that VMWare Server is EOA and end of support soon, what should I use for tests and development for several Linux systems at home?
Ability to run headless and gains in performance due to being bare metal is what i will miss.
Comment: You can't get much more 'bare metal' than ESXi (or vSphere Hypervisor now)
Comment: I liked the simple web-based configuration and being headless.
Answer: If it ain't broke, don't fix it. Do you have a support contract that VMware won't honour or something, are you constantly finding show-stopping bugs in VMware Server that prevents you from working on it until a patch is issued?
That said, Citrix XenServer has been free for a while now.
Answer: You can run virtualbox headless, and get some degree of web based management with phpVirtualBox. Otherwise, you pretty much get what you do with VMware server - i run an instance on a little atom box.
Answer: VMware vSphere Hypervisor (aka ESXi) is a free, bare-metal hypervisor. It's easy to migrate your VMs from VMware Server to vSphere using VMware Converter. In addition to running your existing VMs, vSphere can be upgraded later to add features such as redundancy and live migration.
If you don't need to run your VMs headless, you could use VMware Player (free) or VMware Workstation ($200), both of which can also easily import your existing VMs. VMware Workstation 8 also includes a new sharing feature.
Depending on what kind of testing you do, you might be interested in the clone and snapshot features in vSphere and Workstation. These features make it easy to configure and rollback test machines.
One of the reasons we've retired VMware Server at my office is that the management plugin is no longer updated, and won't run in newer versions of Firefox.
Answer: I use Proxmox VE myself for about 3 years now, very happy about it. It's basically KVM + OpenVZ + Debian + their own custom webui.  It's very user-frinedly, you manage it form the web much like the old VMware server.
I didn't want to go with VMware vSphere or Citrix XenServer as they both run on hypervisor kernels, and may have rather picky hardware requirements.
It comes with KVM guest VM images and OpenVZ-enabled guest kernels for many major Linux distro, available for download within the VM guest setup screen.
There were any mature KVM distro when I selected Proxmox VE, but apperently there's another one based on RHEL/CEntos called OpenNode
http://opennode.activesys.org/
Or you can use regular RHEL/Centos/Debian/Ubuntu distro and add the KVM management tools you want.
http://www.linux-kvm.org/page/Management_Tools
Answer: I found vmware player to have the best performance for local vm's(out of VBox, and vmware), and I use powershell to launch a vmware player VM without a window opening.
Answer: There are a couple options:

Proxmox
Citrix XenServer
Linux + KVM **

** This will required additional setup, but there are some good guides for CentOS, such as http://www.cyberciti.biz/faq/centos-rhel-linux-kvm-virtulization-tutorial/
It isn't completely headless, but you can remove, or ignore the GUI elements. Administration can be done via SSH, or you can install something like Archipel

VMWare Server replacement?


Is there any ebook reader that can synchronize the bookmarks across PC(windows, osx), iOS, android devices?

Question: I am looking for a reader that can synchronize the bookmark at which we last read and can continue from where we left? I have a surface, macbook, ipad, and a samsung tab across which I would like to synchronize the books, and their bookmarks. Amazon Kindle app comes close but doesn't support epubs. Any suggestions?
Answer: Google Play Books is probably what you are looking for. It synchronizes data between all your devices, allows you to upload your own ebooks and it supports epub format.
Answer: Google books which was mentioned by a previous poster is a decent option, but it can be irritating managing your files on the google cloud.
If all you're trying to do is sync your last-read position between devices I would recommend Bluefire Reader paired with a dropbox account.  You'll also need to set up a free Adobe ID and register the Bluefire apps on all your devices to the same Adobe ID to enable syncing.  The only drawback is that it does not sync bookmarks, notes and highlights at this time (although I've spoken with the developer and that functionality is under development).
Comment: The Android version of Bluefire Reader has a lot of recent 1-star reviews. Does that match your experience, or is it perhaps mostly reading PDFs that it's struggling with?  Any insights appreciated!
Comment: I haven't used it with PDFs.  I'm using only ePubs (mostly mobi files I've converted to epub via Calibre).  I currently use the app on my iphone, an android tablet, windows 7 desktop, and windows 8 tablet and it does a good job of syncing.  The only minor issues I've found is there is a slight delay when I open a book before it asks if I want to sync to furthest read position, and if I read on a device then come back to the same device it wants to sync me to a different position than I left off so I have to decline the "jump" option.
Answer: Moon Reader Pro can use Google Drive, DropBox, or WebDav to sync your books across devices. I personally use it with a self-hosted NextCloud.
Answer: I think Kobo is what you're looking for.

The Kobo app syncs all your bookmarks, so you can read between your smartphone, tablet, computer, or Kobo device and pick up right where you last left off.
Comment: In my experience, Kobo will only do this with books that you've purchased from Kobo - not with epubs purchased from elsewhere. Unfortunately!!
Answer: BookFusion does this (iOS, Android, Web) and has a calibre plugin. It is subscription based, but has a free tier.
However, it did not sync highlights between Calibre and BookFusion when I just tested it.
It also does not sync highlights with Kindle, but I don't know any software that does.
Answer: FBReaber can synchronize bookmarks via Google Drive


How are the passive pickups of an electric guitar powered when they are connected to an effects processor?

Question: Having the output as headphones how are the passive pickups powered in an effects processor  ?
Do they take up the power source of the processor itself ?
Comment: 'Passive' => 'not powered'.
Answer: The pickups are "powered" by the movement of the strings. The effects processor amplifies the signal until it's powerful enough to be heard. If you plugged your headphones in directly, there wouldn't be enough signal even when you bang hard on the strings to hear anything through your headphones.
Comment: To be a bit more useful: a moving conductor (the string) next to a magnet (the pickup), induces a current in the magnet (or in the coil around the magnet).  That's the source of the electrical signal.
Answer: Passive pickups
A low level signal is generated by the vibrations of the strings above magnets. This signal is then boosted by a preamp at some stage in the process, whether it is an effects pedal (in your case it sounds like it is), or a power amplifier.
Active pickups
Active pickups differ in that they have a built in, powered preamp which gives a higher level signal before it gets to an effects chain or amplifier. If your guitar has a battery in it, it almost certainly has at least one active pickup on board.
Answer: It may be useful to view magnets as pushing out a stream of "north-pole stuff" out the north pole which wants to find a path to the south pole, and "south-pole stuff" which wants to find a path to the north pole.  In practice, there's only one kind of flux and it doesn't really "travel" from one pole to the other but rather connects them, but imagining flux as "flowing stuff" may be easier than viewing it more abstractly.
Flux repels itself, which means that while a tiny bit of flux may be able to travel from the north pole to the south pole right against the magnet, much of it will have to travel some distance away from the axis of the magnet before traveling from one pole to the other, and then travel back to the magnet.  Because flux travels more easily through steel than through air, the string will allow some flux to quickly flow from a point very near the magnet's axis to a point some distance away, thus making it easier for the flux to get away from the magnet.
Each unit of magnetic flux which encircles a wire as it connects the north and south moles of a magnet will induce a unit of electric flux in the wire; changes in flux translate into voltage.  If a wire is looped into a coil, flux which encircles all the wires on one side of the loop but not the other will induce flux (and thus voltage) on all those wires, and all the induced voltages will add together; any flux which encircles wires all the way will induce flux at different parts of the coil, but some of those parts will cancel others, having no net effect.
A single-coil pickup works by having the spring spread out some of the flux so that it goes through the magnet (which is inside the coil) but returns some distance away (outside the coil).  The closer the string, the greater this effect.
Humbuckers have a more concentrated effect since it's possible for flux to connect the north pole of one magnet to the south pole of another, and the north pole of the second magnet to the south pole of the first.  In a humbucker pickup, north and south poles of opposing magnets sit next to each other in opposite coils.  Thus, any change in the flux which flows through the magnets will affect the flux flowing through the two coils in opposite fashion.  If the coils are wired opposite, this will cause any generated voltage to to be added together.


What is security testing? Please suggest how can I start. Any tools or any methods?

Question: I want to learn security testing. To be candid I have just heard this term and never tried it. Is it beneficial for the product if security testing is done? How can I start? Do organizations value security testing and would it be another asset if added to my skill set?
Comment: check this answer - http://sqa.stackexchange.com/questions/5525/open-source-web-security-testing-tools?rq=1
Comment: same as- http://sqa.stackexchange.com/questions/9275/best-opensource-tool-available-for-security-testing-of-web-applications?rq=1
Comment: I suggest at least looking to see what security testing is.  When you've done a little more legwork, we'd be happy to answer questions about it that can be answered in a single answer.
Answer: There are different types of security testing all with their own path. It could be from actual penetration testing to just risks analysis.
From my experience (in the software development world) security testing is often ignored until a client asks for an audit or only executed after a security breach has happened. This greatly depends on the industry and type of product ofcourse.
I think you can start with a introduction training course like https://www.udemy.com/penetration-testing/ or watch other training video's.
It would certainly be an asset for any serious company, at-least someone should be aware of security risks and have a strategy to mitigate them.
Answer: Things have changed now, most of the companies management is Aware that Security testing should be included as part of Testing.Many critical Banking Applications, E-commerce Websites which stores customer Credit details have to oblige to PCI compliance.
To me, it's really interesting field to Dig bugs that may break down your systems and can get access to sensitive Customer Information or may bring down your systems for a While.Definitely, it will be an Asset for you to learn Penetration testing concepts and to hold a recognised certification.
Where to Start:
If you got no idea about Attacks and Vulnerabilities then start with Cybrary IT this is the place where you can watch lectures on Security concepts for free.
Learn more about OWASP, OWASP Top-10 attacks and their consequences and you feel that you're equipped with concepts of security testing and attacks then start implementing them, testing them practically here
OWASP- WebGoat
Google Gruyere
Test Fire
Once You get practical hands on knowledge on finding vulnerabilities in an Application and implementing security attacks then you may think of tools and browser Add-on's. I feel it's too early for you to play with tools better to learn and implement things before playing around.
To get inspired more sign up to newsletter's of these websites which sends you a daily email of Current Security Hacks happening around.
HackRead
The Hacker News
Hope this information helps you to get started.


What role does a stoneware bowl play in the baking of Artisan bread?

Question: I'm looking into baking sourdough bread; I've read that I must have a stoneware or earthenware baking bowl in order to make it come out with a nice crust. Is this strictly true? Or can I substitute something else, say, baking it directly on my pizza stone with a pan of water underneath to provide steam?
Answer: I don't see any reason to buy anything like that. It is correct though that steam is key to great crust!
You can simply use a spray bottle with water.
What I do, is preheat a flatish sheet in the oven at as high the oven goes (I usually go for 275 degrees C), on the bottom rack. Put the loaf on the pan, and mist the sides of the oven and quickly close the oven door. It's important that you don't have the oven fans on at this point (convection oven).
Reapply mist to the sides of the oven to create steam every 3 minutes or so for 15 minutes, or until you see a firm, nice crust forming. At that point, lower heat to 200 or so, and LET ALL STEAM ESCAPE. I set my oven to use it's fans at this point. Bake until finished (about 40 minutes more when I do my bread).
The reason I put it on the bottom rack is because the pan seals in moisture to the bottom of the loaf, or something like that. Atleast I get better results if I heat the bottom more.
Edit:
Of course, a preheated pizza stone is even better than the pan idea! I just don't have a pizza stone. Go ahead and use that, and you won't be disappointed. You could probably just set it in the middle of the oven, since the preheating will make the stone retain alot of heat.
Answer: Baking on a sheet rather than a pan certainly gives more top-crust.
A lovely dusting of flour on top for thick chewy crust is one traditional option where addition of steam is not ideal -creates plaster!
A nicely oiled metal pan can create a lovely crispy side-crust esp. after rolling dough in seeds or oats etc.
A shiny crust is achieved by a brief fine spraying immediately after baking (not for floured loaves).
The thickest chewiest country sourdough loaves I know are 'Doppelback', double baked, meaning baked longer and slower but never literally double unless you want caramelized pumpernickel...
Answer: You can indeed do what you ask - baking on the pizza stone with a steam pan.  It works better to pour hot water directly in the pan when you put the bread in though, rather than just leaving water in the pan.  You get a burst of steam and then a consistent small amount.  It's a method that Peter Reinhart advocates.
The other common option - especially with high hydration doughs - is to bake it in a covered dutch oven for the first half.  This approximates some of the effect of the earthen/stoneware.  The steam from the bread itself keeps the environment moist.
You certainly don't need those pots for fantastic bread.
Tonights loaf - no earthenware ;) (I rushed it for dinner, so the crumb isn't what it could be.)


Wittgenstein: Why is bipolarity necessary?

Question: I do get that for a certain proposition there may be the possibility of it being either true or false, but why must this possibility exist for every proposition?
Comment: Possibly because propositions are such that they only admit true & false answers.
Answer: This is a deceptively complex question, and very on the nose when it comes to Tractarian interpretation.  My line on this is to say that we need to pay attention to the distinction in the semantics of TLP between "Propositions" (the German "Satz") and "Elementary Propositions" ("Elementarsatz"), and to note the theoretical difficulties in explaining how to cash out the more general notion of Proposition in terms of Truth functions over Elementary Propositions, as in section $5, without sacrificing the Picture Theory approach that makes the semantics of Elementary Propositions seem appealing
For Wittgenstein, although propositional (Elementarsatz, at least) meaning is tied to the existence of states of affairs, how do we explain the meaningfulness of contingently false sentences, such as "It is warmer in Britain than in Australia"?  If there is a state of affairs of objects joined in the way indicated by the sentence, then it is clearly a non-actual one. On the other hand, if there is no such state of affairs, then how do we resolve the reference of the sentence to some other state of affairs so as to preserve sensibility?
We have a choice to make between accepting that non-actual states of affairs can be the subjects of utterance and fleshing out some mechanism by which we speak of the facts of the matter even in error.  Max Black, in his "Companion to Wittgenstein's Tractatus", denotes these two interpretations as Possibility and Fact Theories, respectively, and different philosophers have developed both interpretations of the Tractatus as in keeping with the themes and approaches of the original text (in as much as any interpretation can be in keeping with the TLP).
If we can take it as read that the Truth functions exist as mathematical functions over a Boolean-valued domain, such that there are only two possible truth values that any given proposition might take, then this is a fairly cheap Fact-Theory way to get the additional abstraction over our base level of elementary propositions that we need to speak "falsely about" the facts of the matter.  Elementary propositions describe states of affairs, these states of affairs combine together into "facts" in a way strictly mediated by how complex propositions are structured in boolean functional terms, and the "negative fact" is just a consequence of the negation operation in boolean logic, rather than any kind of complicated alternative possibility.  In the example above, Britain is at least as cold as Australia, and so the falsity of Britain being warmer can be accounted for from the state of affairs describing the relevant climates of the two and the boolean function taking truth to falsity and vice versa.
(In effect, the "possibility" of truth or falsehood in a proposition doesn't commit us to an ontology of alternate universes of states of affairs if we can get this kind of abstract truth function construction going.  We do need such an account, because the more natural way to interpret negative propositions in the picture theory is to point to an inflated ontology with non-actual states of affairs for them to correspond to.  And if we can account for negated propositions in this kind of mathematical way, we get the bivalence of any proposition as part of the package.)
This interpretation is very along lines that Bertrand Russell might have endorsed.  So naturally as Wittgenstein scholars we might want to be skeptical that it's the intended one.  Indeed, there seems reason to suspect that W himself might be interpreting negation some other way.  There is a distinction to be drawn in TLP between "~" negation (the German "Verneinung", or "denial") and the "N(ζ)" "Negation" described in $5.5 in terms of repeated schematic applications of the Sheffer Stroke - the former, if thought of as Boolean negation, is a Semantic conception of negation and the latter Syntactic.  It's the Syntactic version "N(ζ)" that is called upon in $6 to explain the logical form of Truth Functions (rather than the more contemporary tactic of evaluating the definable functions set-theoretically), and hence that informs his conclusion about the limits of what can be logically expressed.
Mathematically, if we think the syntactic conception of negation is the intended one, then as Benubird pointed out above, we don't necessarily thereby commit ourselves to a strictly Boolean logical framework.  For Wittgenstein in the Tractatus, it is entirely possible that problems around infinity and countability hadn't yet come into view (his Philosophy of Mathematics work would come later and largely miss the massive developments happening in Set Theory at the time) but issues around how exactly to cash out this notion of repeated application of functions and the mathematical disputes around foundations and axioms in maths would be very relevant here.  We could entirely well say something very similar about the formal limitations of assertion using Heyting Algebras or some alternative semantic framework as would be favoured by Intuitionists; in which case, we would arrive at a different conclusion of what possible descriptions of the Facts there might be too.
Given what Wittgenstein says throughout about the use of Truth Tables, and his position in the history of mathematics, it seems reasonable to suppose that he was relying on the technology of boolean logic over finite models.  Since model theory, proof theory and set theory have come a long way since the 1920's, we might be more prepared from our current standpoint to deal with pluralities that Wittgenstein as a non-mathematician may not have been aware he was skipping over.
Answer: You can see Gregory Landini's paper : "Wittgenstein's Tractarian Apprenticeship" (Russell: the Journal of Bertrand Russell Studies, 2003) or Landini's book : Wittgenstein's Apprenticeship with Russell (2007).
In "Wittgenstein's Tractarian Apprenticeship", Landini writes (106),

In fact, Wittgenstein's famous self-imposed isolation in Norway "until he has solved all the problems of logic" failed to produce the reduction that Nicod found in 1916. ...
There is no question that Wittgenstein had ideas for improving the philosophical foundation of Principia [...]. For example, Wittgenstein proclaimed that a proper elimination of the identity symbol would obviate Principia's need to add statements of the infinity of individuals as antecedents of central theorems concerning inductive cardinals. He also advocated an extensionalist position that "a function can appear only through its values" and suggested that this would avoid the need for Principia's Reducibility Principle.

The truth-functional foundation of logic (extensionality) was one of the building blocks of the "revolution" in logic of Frege and Russell.
Wittgenstein's Tractatus is born in that "environment"; so is natural that we find it at the core of the book, that was intended as a "philosophical foundation" of the new logic.
Answer: First off, I think we need to understand what is meant by a proposition, how it differs from a fact, which differs from a thing and what it means to bear truth, and what is truth.
Wittgenstein in the opening section of the Tractatus says that:

1.1 The world is the totality of facts, and not of things

Following Kant, we cannot access, the thing-in-itself (ding-an-sich), but we have access to facts. Facts simply are - they do not bear truth-values, that is we do not say that they are true or false. So, what is it that we do when we say something is true or not? According to Wittgenstein:

2.1 We picture facts to ourselves.

Notably the mind must be involved - and it is that picture that we make in our minds that have truth or falsity, that is they have logic, which is confirmed in:

3.0 A logical picture of facts is a thought.

Where logic is introduced. But this  thought, this picture of the facts, is not a proposition. The picture I have of green grass is not the same as the proposition that 'grass is green', which he points out in:

3.1 In a proposition a thought finds an expression that can be perceived by the senses.

This does not mean that a proposition is something that is written or spoken. When a proposition is written out or spoken out aloud, he calls that the sign of the proposition - the perceptible sign - since we can read or hear it:

3.11 We use the perceptible sign of a proposition (spoken or written, etc.) as a projection of a possible situation. The method of projection is to think of the sense of the proposition.
3.12 I call the sign with which we express a thought a propositional sign. And a proposition is a propositional sign in its projective relation to the world.

So a proposition is that which is common to all signs that express it. This is similar to the idea that 'oneness' is common to 1, one, ein, ek etc.
So propositions bear truth - but what is truth for Wittgenstein? He terms it as agreement with the facts of the world or not:

4.3 Truth-possibilities of elementary propositions mean Possibilities of existence and non-existence of states of affairs.

(He excludes tautologies and contradictions as propositions are they are neccessarily true or false, and admit no possibility).
To return to your question:

I do get that for a certain proposition there may be the possibility of it being either true or false, but why must this possibility exist for every proposition?

So, propositions for Wittgenstein must have the possibility of being either true or false; he expressly forbids analytic propositions which by their very form are always true or false. In his view propositions must have possibility. But can one have more than true or false as truth-values? It first appears that the answer to this question must be yes, for in modern logic there are species of logic that are multi-valued, for example intuitionistic logic, but note that this is a formal system and the meta-logic we use to manipulate this formal system is still classical and thus admits only true & false as the only truth-values.
Comment: Surely just by being a proposition about the future, their truth status cannot be evaluated, & an indeterminate truth value is required as a third option?
Answer: It is not true to say that it must exist for every proposition. There are plenty of logic systems that do not admit to only true and false values. For example, see here: http://en.wikipedia.org/wiki/Three-valued_logic
Comment: @user3094719 Ah, I see, sorry. Perhaps you could add a reference in your question, to the specific book/paper where this was written?
Comment: While this certainly is very interesting, it doesn't seem to answer my question. Because my primary goal here is understanding Wittgenstein.