What happens to Protons and Electrons when a Neutron star forms?

Question: What happens to Protons and Electrons when a Neutron star forms? At some point gravity overcomes the Pauli Exclusion Principle ( I assume) and they are all forced together. What happens in the process?
Comment: @LDC3 quantum states always exist, different for different boundary conditions
Comment: I would not state that gravity overcomes the Pauli Exclusion Principle since it is an idea. What gravity does do, is to squeeze all the particles together so that quantum states no longer exists.
Comment: @annav So the quantum states for normal matter are transformed into a different set of quantum states for compressed matter (where RobJeffries indicated that the electrons are degenerate)? Isn't that like saying the theories for normal matter no longer apply and a new set of theories are used? Oh, I should have stated that the quantum states *for normal matter* (and theories) are no longer viable.
Comment: @LDC3 yes, normal matter would be correct. New solutions are needed but still the framework is quantum mechanical.
Comment: Indeed the quantum states are identical and they have a density of $8\pi p^2/h^3$, where $p$ is the momentum, whether we are talking about a perfect gas or a degenerate gas All that changes is the way they are filled.
Answer: It is the Pauli Exclusion Principle that actually allows the formation of a "neutron" star.
In an "ordinary" gas of protons and electrons, nothing would happen - we call that ionized hydrogen!
However, when you squeeze, lots of interesting things happen. The first is that the electrons become "degenerate". The Pauli exclusion principle forbids more than two electrons (one spin up the other spin down) from occupying the same momentum eigenstate (particles in a box occupy quantised momentum states).
In that case what happens is that the electrons "fill up" the low momentum/low energy states and are then forced to fill increasingly higher momentum/energy states. The electrons with large momentum consequently exert a degeneracy pressure, and it is this pressure that supports white dwarf stars.
If the density is increased even further - the energies of degenerate electrons at the top of the momentum/energy distribution get so large that they are capable of interacting with protons (via the weak nuclear force) in a process called inverse beta decay (sometimes referred to as electron capture when the proton is part of a nucleus) to produce a neutron and a neutrino.
$$p + e \rightarrow n + \nu_e$$
Ordinarily, this endothermic process does not occur, or if it does, the free neutron decays back into a proton and electron. However at the densities in  a neutron star, not only can the degenerate electrons have sufficient energy to instigate this reaction, their degeneracy also blocks neutrons from decaying back into electrons and protons. The same is also true of the protons (also fermions), which are also degenerate at neutron star densities.
The net result is an equilibrium between inverse beta decay and beta decay. If too many neutrons are produced, the drop in electron/proton densities leaves holes at the top of their respective energy distributions that can be filled by decaying neutrons. However if too many neutrons decay, the electrons and protons at the tops of their respective energy distributions have sufficient energies to create new neutrons.
Mathematically, this equilibrium is expressed as
$$E_{F,p} + E_{F,e} = E_{F,n},$$
where these are the "Fermi energies" of the degenerate protons, electrons and neutrons respectively, and we have the additional constraint that the Fermi momenta of the electrons and protons are identical (since their number densities would be the same).
At neutron star densities (a few $\times 10^{17}$ kg/m$^{3}$) the ratio of neutrons to protons is of order 100. (The number of protons equals the number of electrons).
This calculation assumes ideal (non-interacting) fermion gases.
At even higher densities (cores of neutron stars) the strong interaction between nucleons in the asymmetric nuclear matter alters the equilibrium above and causes the n/p ratio to decrease to closer to 10.
Comment: @DirkBruere The explosion would only be caused by the release of pressure. Neutron decay is moderated by the weak force and is slow. The half life of a free neutron is 10 minutes!
Comment: @DirkBruere My mistake - the kinetic energy density of the neutrons is $3\times10^{32}$ Jm$^{-3}$. i.e. each neutron has $\sim 30$ MeV of KE and a speed of $\sim 0.2c$.  Hence the ~1MeV released by beta decay and converted largely into KE of electrons and protons is a  minor perturbation (impressive though it is).
Comment: So the implication is that if we could remove a cubic metre of neutronium from a neutron star and put it in free space, we would get a very large explosion as neutrons decayed and released energy?
Comment: OK - let's add some numbers. We have 10^17 kg of neutrons, which means we get a decay of about 10^16 kg every 10 minutes or about 10^13 kg per second. That's about 10^40 neutrons/second. If each releases 0.7MeV we get about 10^45 eV which is around 10^26 J/s or roughly 10^11 megatonne equivalent nuclear explosion. Which is quite a lot.
Comment: @DirkBruere Actually, it more like $5\times 10^{16}$ kg of neutrons in the first 10 minutes. Since this is an exponential decay, more than half of it ($2.5\times 10^{16}$ kg) will have decayed in the first 210 seconds (approximately).
Answer: Well let's talk about in a completely normal perspective. When a main sequence star loses its fuel it has to start combining heavier elements right? So hydrogen fuses to helium. Helium to carbon and oxygen. So for star like sun it does of have enough gravity to trigger helium fusion. As a result the core of the star gets crushed until the carbon is fused and electron degeneracy pressure kicks in to maintain the carbon core to form a white dwarf. In case of larger stars the gravity has enough power to overcome this electron degeneracy pressure and breaks their orbitals to push the electrons into the nucleus of the atom. Here the strong nuclear force takes over and the electrons and protons combine to give u neutrons, neutrinos and gamma rays. If the star is large enough it can even crush the neutrons and ultimately ends up as a black hole. However there is also another phenomenon known as a hypernova. Where a star is 200 times or so massive than the sun when it goes supernova there won't be a remnant left.


Do I lose reputation if I answer a downvoted question?

Question: Do I lose reputation if I am answering a downvoted question?
Comment: You can read the help page for more information
Comment: No, BUT there are users who, if they believe a question is bad, will downvote answers to that question to indicate that they think it's a bad idea to answer bad questions, and also to make it easier to delete such questions.
Answer: No. You only lose reputation for downvoting answer, or having your questions or answers downvoted. Answering questions is the core function in Stack Exchange, and you won't lose any reputation whether the question is downvoted or not.
Comment: It might be noteworthy to add that questions that tend to net a lot of downvotes are PSQs and the other types of problems that tend to get eventually closed and/or deleted. If deleted, you will lose the rep from your answer. In that light, if you're concerned about your rep, it might not be a good idea to answer questions that are accumulating a lot of downvotes/close votes, since your effort may be ultimately wasted (again, on the premise your concern is solely with rep).
Comment: @EeveeTrainer Actually, even for people not concerned too much about rep, they may not wish to spend a lot of time & effort answering questions if their answer will be deleted some time later. It could definitely help the OP, and perhaps other people, for a while, but it won't have the long term value of adding to the knowledge base here that would occur if the question/answer wasn't deleted. Also, I myself generally prefer to not answer PSQs, or to just give minimal hints/answers if I do, to avoid encouraging those types of questions, as I prefer the OPs to show some context/effort.
Comment: @Ooker As for how to handle PSQs, I believe there is generally less agreement, such as in terms of closing & answering them. Some people believe it's best to just always close them, while others believe that, if they believe the OP (Original Poster) is sincere but just has done a poor job asking, they should give a hint or start of an answer, enough to help prod the OP to solve the problem themselves. As for myself, I tend more to the former than the latter, but as with most things in life, each situation is somewhat unique.
Comment: @John what is PSQ? I think answering those questions are still beneficial to you, because bad questions usually contain implicit assumptions that need to be revealed. The job of the answerers is to help the asker to realize these assumptions. So even if the answers are gone, the answerers can know what assumptions novices likely to have, and be prepared for the next one.
Comment: @Ooker PSQ is short for "Problem Statement Question" that's basically just a question of a problem statement, such as word for word from a book or assignment, with no context given, e.g., what, if anything, in particular the user is unsure of, what the person's tried (& possibly had difficulty with), where the question comes from, etc. A site as relatively large as this has a diverse set of users & opinions, but I believe a fairly general consensus is we want to be careful with PSQs as we don't want to become a "homework site" where people expect us to just do their homework for them.
Comment: @John I see. My previous comment is meant for unclear or too broad questions, that makes you see it wrong in so many ways, but unable to tell exactly where it's wrong
Comment: @Ooker As for answering PSQs also helping me, such as "implicit assumptions that need to be revealed", I can determine a lot of that just by reading the question itself. To the extent that answering, including getting feedback, will help in this way, I can also get a lot of that from answering relativelyh well-asked questions, where the OP has shown they've done some work, have thought carefully about what they don't know (& sometimes what they do), with this resulting in them asking a fairly good question that, quite often, I enjoy more answering.
Comment: @Ooker You're correct, "unclear or too broad" questions aren't quite the same thing, especially the "too broad" part. However, the wording here of "unclear" is quite often used with PSQ's, even if they're stated clearly, in addition to questions where it's sometimes hard to tell what the OP is actually asking about. As for answering questions which are "too broad", I agree this could have certain benefits if it causes me to think of things in a different way, including things like the perception the question is "too broad". Also, as you state below, we may wish to get clarification if unclear.
Comment: yes I agree. It's enjoying to answer well-put questions. I just want to focus more on unclear ones, because usually they are also the ones OPs put effort in, but still receive negative votes. This brings confusion and frustration for both sides to communicate with each other


What should a pilot do when flying in the vicinity of parachute jumpers?

Question: There are several airfields nearby where parachuting activities routinely take place. How far away is considered to be a safe distance from the airfield when flying past it en-route to another destination? Are there any particular frequencies to monitor besides the airfield frequency? How would I know parachuting is happening besides any NOTAMs?
Comment: @ratchetfreak Activity on the airfield? Isn't any airfield going to have some sort of activity? And parachutes aren't as visible as you might think.
Comment: @CGCampbell: I'd love to know the legal repercussions on the *owner* if an incident had occurred.  In Sailing it is a fundamental principle that powered vessels are legally required to stay clear of non-powered vehicles, and motorized vessels must stay clear of non-motorized vessels. The only exceptions are for commercial vessels travelling at low speeds giving them no steerageway.
Comment: @PieterGeerkens I was with the command group during the discussions and it was decided that two jumps for the days was enough, mostly due to changing weather. No report was made (that I am aware) to any civil aviation authority, and the Captain decided it added more "real world uncertainties" to the drops. The troops cussed him (the owner) out and just got on to the days business.
Comment: activity on the airfield and those big colored pieces of fabric coming down is a telltale sign :)
Comment: While in the Maryland Army National Guard, I accompanied a LURP Company to their drop zone (as a public affairs NCO to take pictures). They had contracted a private field (in WV) as a DZ. We were in the middle of their second drops of the day, when the field owner took off in an experimental light craft, right through the DZ. It was sheer luck that two troops came down to the left and right of him, instead of in front of... that was the scariest airport moment of my career. Afterward, the CO had a talk with the pilot, who said (basically) "my field, I take off when I want."
Comment: If the field wasn't contracted as exclusive use only, it's good ol' see and avoid even during a jump...
Answer: Qualification: I worked at a busy drop zone for 10 years.
Just announce yourself on the airfield frequency about 5-10 minutes out and they'll tell you what's going on, including which runway is active and how high they are jumping from - standard altitudes are 3000ft and 12,000ft AGL. At our place it was really simple: left-hand for 34, right-hand for 16. We landed everyone on the east side, and if we are dropping at 3000 all day you can just pop up to 4000 and be completely out of the way.
Under no circumstances make a cross-field pass as that's usually right in the middle of everyone else's landing pattern, and we don't carry radios.
If you are just passing by a 2km buffer is lots - no one is likely to be in the air that far away.
No reply usually means nothing in the air.
Comment: What if the airfield is private and has no published frequency on the charts? That is the situation for one of the airfields nearby that are labeled as a parachute jump site. I happened to fly by it while on flight following and ATC notified me about parachuting, but if I hadn't been on flight following I wouldn't know. 2 km, I will use 2 miles, seems like a reasonable distance to remain clear. Thanks.
Answer: First of all, recurring DZ's have parachute symbols on sectional charts, so look for them!
The FAA regulations have this to say:
Federal Aviation Regulation Part 105.25 requires that ATC be notified no earlier than 24
hours before or no later than one hour before the parachute operation begins in Class E
and G airspace. Jumps in Class A, B, C and D airspace require an authorization from ATC.

This means that if you expect chute activity in the area, ask ATC!
Controllers are required to give traffic advisories to jump aircraft before the jump,
and to issue advisories to all known aircraft that will transit the Class E airspace
within which the jump operations will occur. When time or the number of aircraft make
individual transmissions impractical, advisories to nonparticipating aircraft may be
broadcast on appropriate frequencies.

And as always, check the NOTAMS!
Comment: I would say this is a judgement call. See and avoid is always a good fallback when unsure. Give them as much room as you think is safe, and them give them a little more.
Comment: That doesn't answer the question of how far. Will ATC provide separation? I assume it's not just a matter of see and avoid
Comment: The parachute symbols on sectionals can be unreliable.  If often takes years to get the symbol added. Once the parachute symbol is on the chart, it seems like they never go away.  The "Pig Farm" in southeast Wisconsin still has the symbol, even though there hasn't been jumping there since the 90s.
Answer:
Are there any particular frequencies to monitor besides the airfield
  frequency? How would I know parachuting is happening besides any
  NOTAMs?

Here in Seattle, jump aircraft are usually talking with ATC (Seattle Approach). The jump airplane will announce 5 minutes out and the when the jump occurs.
Comment: The 5 minute to jump contacting of ATC is required by law!
Answer: In Europe, it's generally a good idea to be on the Flight Information Service (FIS) frequency, where you can receive information about active drop zones and/traffic information to the airplane performing the drop, as they need to call in on the FIS frequency and announce when they start the drop.
Answer: I'm not a pilot. I did attempt to get a parachute license, but stopped after a couple of jumps. I jumped at two different drop zones. (And I'm from Sweden) I just thought I'd offer a view from the other side.
At the DZs where I jumped, the pilot always talked to ATC before takeoff, so I would assume that ATC will know of any parachute activity.
The parachutists will fall, so if you can stay above the plane that will drop them, you'll be fine. Where I jumped, 4000 m was highest allowed altitude without oxygen, so no one jumped from higher than that.
The parachutists will want to land at or very close to their field. During the freefall part, they don't really drift with the wind. Chutes will typically be opened at about 1000 m, and from that altitude, they will drift significantly with the wind. Thus, they will be dropped upwind, and will typically not move very far downwind of the field, especially not at high altitudes.
So, in order of simplest/safest:

Fly above them
Fly downwind of their landing spot
If you need to fly close to their field, the higher up you can be, the better.

This should perhaps be taken with a few grains of salt, but hopefully others can chime in if I've said something incredibly stupid. :)
Comment: Welcome to Aviation.SE gibson. It's always good to have a view from a different perspective.


sccm 2007 SP2 SUP settings

Question: When I try to add a SUP by adding a new site system. I try to select products but there are only older products in there. For example there isnt any office 2007 just 2003 and the only os are XP and windows vista.
Any ideas how I can fix this?
Answer: When you add the primary SUP, it will only have the applications that are listed in WSUS.  This list is updated the next time WSUS syncs with its upstream (i.e. Microsoft).  After WSUS is sync'd, you can look inside its configuration and see all of the new apps that can be downloaded.  Even though you're using SCCM to send out updates, you have to use the WSUS console to identify which updates you want to download.  After the WSUS database is made current, SCCM must also sync its own database.  This can be manually commanded from the Software Updates node or will happen periodically on its own.
Note that if this is a secondary SUP, it should be getting all of its settings from the upstream site.

sccm 2007 SP2 SUP settings


Are there Machete weapon stats?

Question: I was wondering if there was a specific cost, damage, weight, and other properties for a machete as a weapon in 5e. The Player's Handbook doesn't have anything listed for it. I've also been trying to look at the D and D wiki online to see if I can base the stats off another weapon, but I can't reach a consensus there, either. Some say it should be 1d8 slashing while others say 1d6, and they also have weapon variants listed for both scimitars and handaxes that are similar to machetes. Any advice?
Comment: [Related](https://rpg.stackexchange.com/questions/109306/why-does-dandwiki-have-a-poor-reputation)
Answer: It's a scimitar.
Don't let the name fool you - what D&D calls a scimitar is more properly a machete, parang or kukhri. It's a light weapon that can be used with finesse.
Answer: 5e isn't particularly comprehensive with it's weapon categorizations, but it doesn't particularly care to be, either.
I'd probably take the stats from hand axe over scimitar.  Machetes that I've used have been short chopping tools that rely on their weight to aid the work.  They work more like a very broad-bladed axe than a knife.  I'd not consider them a weapon you could use with finesse.  However, they've also been gardening or trail machetes, not weapons of war.
That's really all you're deciding here.  "Can it actually be used with finesse?"  If yes, then scimitar, else, probably hand axe.
Comment: Scimitars are military weapons; machetes are tools with incidental martial applications. I would think a machete would be equivalent to a simple melee weapon, maybe a sickle. I think giving it finesse overstates its suitability for use with martial technique, and making it a military weapon means that untrained farmers and foresters aren't going to be proficient with it (as they would be with pitchforks and axes).

So: your answer can be improved by adding simple vs. martial as another factor to decide.
Comment: Haven't you ever seen someone carve a tiki totem with a machete?  That's finesse.  ;)  So OK, if it matters that much, make a new entry on your table for "machete", and give it the same stats as a scimitar except it doesn't have the finesse property.  And probably costs less.
Comment: @PhilBoncer I've seen someone carve an angel out of ice with a chainsaw.  The Veiled Virgin was carved with a hammer and chisel.  Doesn't mean they're finesse weapons.
Comment: Hand axes, though, have the "thrown" property, which is not necessarily appropriate for a machete.
Comment: @PhilBoncer It's much more appropriate than finesse, in my opinion.
Answer: D&D 5e is not that finely detailed.  A glaive has the same stats as a halberd.  A battle axe is exactly the same as a longsword except for weight and cost.  Call it a scimitar, and you'll be fine.
Answer: Scimitar is probably the closest match, but looking at how machetes are used it's not a very good one.
I would argue that it should be a simple weapon (used almost exclusively by farmers and such) that does d6 slashing damage and is not a finesse weapon (they are generally balanced towards the end of the blade for stronger chopping power, not really nimble when used as a weapon). It should also be quite cheap.

Are there Machete weapon stats?


Does more ocean on an Earth analog produce a different rotation period?

Question: Would an exoplanet that has more ocean than Earth rotate at a different speed as a result of this? Would the amount of water impact the weight, gravitational pull, and/or tidal forces and cause a difference in the exoplanet's rotation period?  (For simplicity's sake, say, if it was earth-like in every respect other than having more ocean than Earth does at about 70% of the surface area.)
Answer:
Would an exoplanet that has more ocean than Earth rotate at a
  different speed as a result of this?

Basically no.   Rotation speed, or angular velocity doesn't measurably change with your proposed example.
To explain this in more detail, there's two important concepts.  First, is Angular Momentum, (Short explanation or longer) and the 2nd concept is Moment of Inertia.
The basic formula is that Angular velocity (time for 1 full rotation) = Angular Momentum divided by Moment of Inertia.  Formulas and explanations are in the link(s) above, and if I was to explain it, it would get wordy, but your question seemed to be more general, less about doing the mathematical calculations, so I'll skip the formulas.
In nutshell, talking about a planet, the state of matter doesn't affect the angular momentum.   Angular momentum is conserved and that, divided by moment of inertia determines rotation speed.  Now if you get something spinning fast enough the angular rotation can overwhelm the gravity and when this happens, the planet can begin to fly apart, which happens more easily with water than a rocky surface which has some cohesion, but ignoring crazy super fast rotations, a water world, a deep ocean world, a shallow ocean world and a rocky world all obey the the angular velocity law and composition doesn't matter.  The angular momentum is conserved.  The moment of inertia of a planet can change but for the most part, doesn't change much.
The Earth's moment of Inertia, for example, changes as glaciers grow or shrink, or when there's an earthquake.   Even, every time we a tall building is built the Earth's moment of inertia increases a teeny tiny bit, similar to a skater extending their arms to slow down coming out of a spiral.
When there's an earthquake which, for the most part, settles the Earth, there's a small increases in the Earth's rotational speed.   The total angular momentum and total mass remaining the same but shifting of material changes the moment of inertia.   (Granted space dust and tidal effects change the Earth's moment of Inertia, but quite slowly).

Would the amount of water impact the weight, gravitational pull,
  and/or tidal forces and cause a difference in the exoplanet's rotation
  period?

This is harder question to answer precisely because adding water changes the mass of the planet and changing the mass changes the moment of inertia, but sticking to the principal of your question, there's no measurable effect.
Lets take a somewhat simpler example without changing the planet's mass.  Ice ages.  When the Earth is in an ice age there's less liquid oceans and more ice at the poles but the total mass is unchanged.   More mass at the poles and less mass in the oceans decreases the Earth's moment of inertia because the bulk of the Earth's moment of inertia is around the equator,  so, as a result, the Earth rotates slightly faster during an ice age and slightly slower after an ice age.   Over time, the Earth's crust has a tendency adjust for this effect but that takes tens of thousands of years.  Parts of the Earth's crust is still rebounding from the last ice age.
Gravitational pull isn't relevant.  Neutron Stars with enormous gravitational pull can rotate very fast and the planet with the fastest rotation in our solar-system is Jupiter and the one with the slowest rotation is Mercury.   Angular velocity has no direct correlation to mass or gravity though there is an indirect correlation.   As a star, for example condenses it's rotation speeds up, because the angular momentum is conserved but as it settles the moment of inertia decreases.   That's why young stars, White Dwarfs and Neutron stars can spin very fast.
Tidal forces can create drag on rotation but the effect is slow, taking millions or hundreds of millions of years.  With enough time, tidal forces cause a planet or moon to stop rotating and become tidally locked but there's no short term affect.  (I'll say a bit more on this later).
So, a planet with large oceans wouldn't rotate any slower than a planet with no oceans because liquid or solid can have equal angular velocity, but over time, tides will slow a planet with oceans more quickly than a planet without them.
Because the Earth has oceans, the Moon's gravitation on the Earth's tidal bulge does slow down the Earth's rotation, but this has been happening for 4 billion years and the Earth still rotates every 24 hours - one of the faster planets.   If the Earth had more water the Moon's tidal tug would slow the earth down a bit faster, but it would still be very gradual.
Jupiter, which is basically a ball of gas, is the fastest rotating planet and Mercury, basically a rock, the slowest, so those are 2 examples of composition not being a factor, though Mercury's slow rotation is in large part due to the strong tidal forces it receives from the Sun.
Now, I Understand the logical approach to your question, as there's something apparent about water resisting rotation - touched on in this question, but the fact that water doesn't spin with a glass when you spin a glass is an example of conservation of angular momentum, not an argument against it.  On a planet, the oceans are rotating with the planet and the angular momentum is already there.
Hope that wasn't too long, but that's the gist of it.   I can try to clean up or clarify if needed.
Answer: If the mass, radius and total angular momentum of the planet is the same as Earth, then I can put forward an answer. (Of course if the angular momentum is allowed to be different you could have any rotation rate...)
First, surface gravity is unchanged since this only depends on the mass and radius of a planet.
Second, if the mass is constant then the average density must be the same as Earth. But water is less dense than the average density of the Earth, so the interior of the planet would need to be denser than that of the Earth in order for the average to be similar.
If the density is higher than Earth on the inside, but lower on the outside, then the moment of inertia, which depends on how far mass is from the axis of rotation squared, will be lower. Then, because angular momentum (assumed constant) is the product of moment of inertia and rotation rate, we deduce that the rotation rate would need to be faster.
NB: Simply covering a larger area with Earthlike ocean would make hardly any difference whatsoever. You need a lot of surface water to make a difference.
Answer: I would assume so seeing as how it would change the density
If it is exactly like earth but has a crap ton more of an ocean- it is perceivable that it's (average) density would be lower,
Also, minutely, it would compress this water more and heat it and make something of an atmosphere given that it doesn't escape. Trapping more and more energetic particles into a thick foggy atmosphere  can change the rotation so slightly it will probably never be noticed.....
Also, if it has a moon, tides/ waves due to gravity can also minutely push the planet in a different state of rotation. Very slightly
I read it wrong, but I'm keeping that in case it helps.
It really depends on how much more water there is. If it was 100% coverage, it would be more "tidy" and the ocean would certainly be more compact (same mass as earth, but add A HUGE amount of water to that to get from 70% to 100% coverage of the area)-- tides may not be as wild. I suppose it would effect the rotation period, but not much.
Note, it might be easier to post this on physics stack exchange, you get better answers, much sooner. This seems like a good question to get up votes off of...
Comment: Does that help?


Taping drywall of different thickness

Question: I am patching some plaster with some drywall and have shimmed out the drywall. The issue is that the plaster isn't a consistent thickness. Some spots it's flush and others its off by 1/8". What's the right course of action to level these out? Paper or fiberglass tape with that big of a difference would make the bulge worse. Heard of a product called fibafuse that might be good for this? Recommendations?
Comment: Would have been easier to replace the plaster...
https://diy.stackexchange.com/questions/85754/
Answer: With uneven work like that you will have to build up the sheetrock side I use a wide mud knife at least 12" when trying to cover uneven areas, as far as the kind of tape paper or fiberglass I use both but preferr fiberglass in this case as it helps reduce cracking. Also I would not do in 1 coat but use several thinner layers. For areas like this I will use "hot mud" because it sets quickly and in some cases as soon as the first layer is complete the starting area is dry just don't mix two much up or you may have a mud tray that turns into a brick before you get done. The last caution is hot mud is tough to sand so I will put my base coats on then a thin layer of topping mud very easy to sand but it takes a day to dry.
Comment: are you saying that in addition to tapering towards the low side I will have to build up a bit on the high side as well?
Comment: You need to bridge the crack with mesh or paper or it will show, you may be able to sand some material down so the bump will not be noticeable but if you only fill the crack it will show later that's why we use paper or mesh.
Comment: I believe he means build up wherever it's low. The picture is somewhat of an optical illusion, at first glance it appears that the drywall side is low but if you decipher the way the measuring tape is held between the two sides you can figure out the plaster side is the low side.
Answer: I would sand down the plaster side, about 6-8 inches in from the joint, then add tape and feather out as normal. There really is no other way to mask the rise that would be seen from adding taping compound over the existing plaster. Save for adding a ridiculous amount of compound to the new drywall.
Comment: If the drywall is higher should I sand down the drywall side?

Taping drywall of different thickness


Dragons and aviation bureaucracy, the sequel: Dragons on Instruments!

Question: Starting with the background provided in this question, how would a dragon outfit himself/herself (avionics, power systems, etal) for operating under the Instrument Flight Rules?  How would the process of obtaining their instrument rating work?  Also, how would this differ if dragons were susceptible to spatial disorientation vs. if they were resistant or immune to it?  What would a dragon sound like in ATC's ears?  How would they file flight plans?  What weather minima would they have?
Comment: When I first read the title for this I had a mental image of a dragon brass band...
Comment: Slightly out of scope of THIS question, so as a comment: While I would still think that "avoiding collision" would mostly be he dragons job because it is easier for them, I WOULD perhaps encourage them to carry a transponder to make things easier for airplane-pilots.
Comment: I hope we, uh, regulate allowable emissions... We don't want any jet-powered dragons zooming about.
Comment: @Layna -- not out of scope at all!
Comment: Brass band - yes, I though that immediately. Dragons trumpeting! But they'd melt when playing jazz, surely?
Comment: @2012rcampion -- the existing answers have bits and bobs of what I'm after, but nobody's explored this topic in-depth yet
Comment: I don't see why a dragon should want to fly IFR in the first place? Plus, i have a feeling that ATCs would hate to handle the separation issues. But if they do, they will at least need radio, compass, transponder and an altimeter.
Comment: @Burki -- because "I'd rather not be late to my dinner appointment, but the coastal stratus layer's moved in...oh wait, IFR!"  And of course!  The question is more about to package all the pieces in a way that the dragon can use them (especially with having to change frequencies/squawk codes/waypoints/approaches in flight)
Comment: These questions make me wonder what the Radar profile of a dragon would be.  Also, what kinds of Dracoforms have which characteristics?  Could a Traditional Western Dragon get type certified more Easily than a Wyvern?  Would a Quetzacoatl kind of feathered Serpent be able to to a maintain The same cruising altitude as an Oriental Dragon?  Finally, would they be good for grass field landings, or would they cause too much damage and have to land on concrete.  Finally, A dragon sax player would go through a heck of a lot of reeds
Answer: Spatial Disorientation
Remember that the air is the dragon's natural environment, so dragons will probably be much harder to disorient.  Disorientation is the result of environmental cues (rotation rates and accelerations) in a maneuvering aircraft that differ greatly from what humans experience on the ground.  Our brains never evolved to handle rotation in multiple axes, and fail to correctly figure out what's going on.  A dragon (or any flying animal) has a brain evolved to process flying, and so will be as resistant to disorientation as a human walking along the ground.
Instruments
Dragons will probably have a different definition of IFR flight than fixed-wing aircraft.  Since they fly slower and are vastly more maneuverable (due to highly variable wing geometry), the risk of collision is reduced even in low-visibility conditions.  Flying through thick clouds or heavy rain will still carry the risk of collision, but I doubt dragons would do much flying through thunderstorms; after all, they aren't protected from the elements by a plane!
Also note that dragons already have all the senses they need to fly: unlike humans, who can't feel airspeed, for example.  A dragon probably wouldn't need instruments to supplement their senses, only for navigation.  After all, people use GPS even when they're walking!  A dragon-flight GPS would be more like an aircraft's flight computer, calculating more efficient paths to take advantage of high-altitude winds.
Flight Plans
You don't file a walking plan to head down to the grocery store: dragons probably wouldn't need one either.  The reason aircraft are required to file a flight plan is due to the collision risk (already discussed above) and the fact there are relatively few flights, and most flights cover a long distance.  Assuming that there would be hundreds of millions of flight plans filed per day, most of which cover distances of a few miles or less, the FAA would probably not regulate them merely due to the inconvenience.
Comment: Remember that *all* flights in Class A airspace are conducted under the Instrument Flight Rules...but you have a point re: instruments and slow flight -- that's why approach categories and copter IAPs exist.
Comment: They wouldn't get up into jet airspace -- they'd be more akin to a turboprop in their choice of cruise altitudes in long-haul flight; they'd benefit from the ability to vary wing sweep and incidence, though. I'd expect them to have a fairly lightly loaded wing for their size class and weight...150kg/m3 would be reasonable, I suppose, especially considering they could fold their wings for ground handling purposes?
Comment: Their wing loading could vary hugely depending on your "source" for your dragons. Many recent stories explain away the "they're too heavy" problem through use of lighter than air gas-filled sacs, which could dramatically reduce wing loading. We also have no idea if Dragons produce lift with their bodies (blended wing Dragons) or use magic etc
Comment: AFAIK, in the US, even planes don't need a flight plan unless they're IFR, and in most airspace you don't need any sort of ATC clearance (or even a radio).
Comment: @Shalvenay Slow banked turns without visual cues fool humans for two reasons: one, the brain expects the perceived gravity to be vertical, and two, the inner ear responds only to angular acceleration and so can't detect the turn.  We had no evolutionary pressure for these senses to evolve in a manner that supports flight: not so for flying creatures.  Evolution would ensure that dragons have the senses to correctly navigate their 3-d environment without disorientation (after all, a dragon who can't figure out which way is up will be eaten by one who can!).
Comment: @Shalvenay I guess I was thinking of dragons as low-altitude fliers, but now that I re-read your previous question I see you specifically stated "getting into Class A airspace wouldn't be terribly challenging."  Then again, would they fly that high on regular basis?  Generally the higher you get, the thinner the air, and the faster you need to go; and the more you exert yourself.  What's their [wing loading](http://en.wikipedia.org/wiki/Wing_loading) like?
Comment: And dragons know which way is down by feeling the strain on their wings, pilots don't have that luxury.
Comment: @JonStory -- blended wing-body structures would make sense for something that needs all the lift it can get.
Comment: @cpast -- correct!  There's a *lot* of Class G you can bumble around in NORDO...
Comment: @ratchetfreak -- banked turns can still fool them as to "down" though...or even more extreme maneuvers (cue Bob Hoover pouring iced tea).
Comment: @2012rcampion -- yes, although the evidence with RL birds re: blind flying is sparse and mixed.  I'd be inclined to make them spatial-disorientation-resistant, myself, even...
Answer: Ok, I am trying this without much actual aviation-knowledge, but have been encouraged that this is not out of scope (I actually have no clear idea where IRF-regulations start and end... I know what a dragon looks like, though ^^).
As this answer points out, dragons will most likely not require instruments to see. But they will be safer if SEEN. collision-avoidance would most likely be mainly for the dragons to manage, because they just have an easier time manoeuvring, but for IRF for pilots, it would be helpful if Dragon got Transponders to signal their position.
About weather-minimums: It really would fully depend on the dragons again. They may avoid flying in thunderstorms naturally, and at the same time be perfectly content to start, fly, and land in the middle of the most terrible blizzard... perhaps they just don't get cold, but lightening is an actual danger.
Winds are just as dragon-dependent: if they have capabilities for in-storm-flight like, say, an Albatross, even a strong hurricane may not keep them down.
In bad enough conditions, they may actually have the airspace to themselves!
About what they may sound like to ATC: This is Dragon 101, I am patiently flapping my wings above your tower, may I please land on it until you have the metal-tubes sorted out?
A bit more serious: I would not imagine them much different from normal ATC-talk, just perhaps a bit impatient with those clumsy humans :).
Something that just came to mind about flight plans: we have airways defined for airplanes anyway. Would dragons OUTSIDE these airways be regulated at all? If not, the problem may actually be reduced to having controls in place for "crossing the street" and "I want to land near the airport, please". Dragons purely amongst themselves pose a lot fewer problems that dragons and airplanes.
Comment: With GPS and FMS computers, it's now possible for airplanes to fly off-airway (and they do so routinely, even, or so I hear ;)
Answer: I think a dragon would still be at the mercy of the FAA.
As with all government entities, they don't like it much when something new enters their jurisdiction, and is unregulated.
They would issue a large stack of amendments to cover operations in controlled airspace (after the review boards, consultants, lawyers, military and other bodies with an interest got through their 'fact finding missions' in the Bahamas).
I'm not convinced that a dragon would have better situational and navigational awareness than say, an AWACS aircraft, which is still required to follow IFR and have ATC clearance in controlled airspace.
Minimum instruments would have to include:
Backup attitude indicator: A requirement for IFR at any rate. In order to avoid spatial disorientation. As mentioned before, dragons would likely have a much better sense of motion and balance in three dimensions than a 'seat of the pants' human pilot. But I'm guessing disorientation might still be a factor.
Transponder: With presumably better vision than a human, in a wider range of wavelengths than humans, you're still dealing with airspace full of aircraft operating at a range of airspeeds. ATC would need to be able to maintain separation speeds.
Coms: The dragon would be required to carry two radios.
Radio NAV:
ATC:"Dragon Zero One, Dulles Departures. Can you confirm that you are outbound on the two two zero radial?"
Dragon 01: "Departures, Dragon Zero One. Negative, I don't have VOR".
ATC: "Fail."
TCAS: Not sure what the FAA regs are (I've been out of the game for a while), but TCAS wouldn't hurt.
ASI: Regardless of how well a dragon thinks it can fly, ATC would need it to maintain airspeeds accurately for separation.
Altimeter: Same again. ATC would need to know that the dragon was following a set flight level. Would need it to provide data to the transponder anyway.
Nav lights: Red port and green starboard lights at least. And strobe light. And landing lights.
Another thing to consider: What is the dragon's max cruising altitude? Does the fire breath deplete the oxygen available to the dragon in flight, and at lower air densities? Would supplemental oxygen be required in Class A airspace and/or above 10,000 feet? How would an oxygen rich environment affect fire breath safety?
Other considerations: Weight and balance calculations, and loading charts. As the dragon grows, the weight and balance might need to be recalculated. Possible recertification every year until maturity, then every two years thereafter?
Communication with ATC would have to be in English, the international language of aviation. A dragon would need to be conversant using standardised aviation phraseology. If it's good enough for (or at least tolerated by) the Chinese, French and Russians, it's good enough for dragons.
Comment: One other thing -- how do you interface all this to the dragon, especially since he'll have to do things like tune navaids and radios, change squawk codes/ident, and punch in waypoints while on the wing?
Comment: @Shalvenay The interface would be easy. If the number of dragons needing this stuff was high enough the market would come to the party. Dragon ergonomics consultants, dragon performance and limitations experts would pop out of the woodwork for a dollar. Icom would make wrist mounted nav/coms plugged into a Senheiser headset. An Apple iPad does half the flying these days, strapped to the other arm. Samsung would say theirs is better. TCAS on the head. All wired to an electronics pod on the dragon's back. A chest bag for all the checklists, QRH, Jeppessens, regulations, and a thermos for coffee.
Comment: I doubt the balance calculations would matter as much as they do now for fixed wing AC.  Balancing is a function of keeping the AC level and controlled in flight.  The Dragon would do this instinctively.  Weight would also be handled instinctively, but would need to be measured for it's impact on the runways
Answer: A dragon is a different beast than an airplane (yes, pun intended).
An aircraft goes from airport A to airport B. It can only stop at airport B (or, when needed, in airport C). Reports are required to metereological service, describing the weather all along the route. The path is seriosly studied by the crew, attending to atmospheric conditions and other considerations.
If, despite that, at mid travel the airplane crew finds that visibility is very reduced, it has two options:

Return to airport A or go back to airport C. Big fuss about time lost, and the passage is not anywhere near B (unless they had luck chosing C). Then deal with the pasengers, refuel, wait for the storm to pass and for the company to assign planes/crew for the new flight. And, when they try again going to B, there is no guarantee that the weather will not become worse again.
Try to flight in less than perfect conditions, expecting that technology will be enough to compensate for lack of visibility.

Now, a dragon wants to go from point A to point B. He gets in the general direction towards B and starts flying. If he finds bad weather, he looks down, finds some clear ground $^1$ and lands. Depending of how tired he is, he will take a nap or he will visit the nearest village, hoping for a maiden to kidnap.
He can repeat it as many times as needed, and with each "jump" he will become closer to his objective. And, in the worse of weather, he can still walk...
$^1$ In case there is no clear ground, burns some houses/fields until there is.
Comment: Applies to commercial aircraft, but a dragon is closer to small private plane - the archtypical Cessna 172.  You've a much larger choice of landing spots - dirt & grass strips, rural roads (watch for power poles!), dry lakes, &c - in a small plane, and if you stay VFR and out of controlled airspace, don't have to worry about flight plans or ATC.  A dragon could presumably land & take off most anywhere, more like a helicopter.
Comment: @jamesqf -- exactly...but there are still benefits to operating within the IFR system, access to higher altitude airspace being only one of them.
Comment: So when humans turn up with transponders and weather forecasts, suddenly life gets a lot easier for dragons. With a bluetooth headset our dragon could even keep in touch with his mates as well as interfacing with ATC.


Making heat map based on values assigned to polygon using ArcGIS Pro?

Question: I am very new to ArcGIS Pro and I have loaded a SHP file with polygons and associated 'scores'. I would like to create a heat map based on these values e.g. a value of 1 would colour the polygon red, a value of 5 would colour it orange and a value of 10 would colour it green.
Answer: It's pretty simple in ArcGIS Pro once you know where to go to do it.
First- select your layer in the Contents tab on the left

Then, go the Feature Layer Tab along the top and click on the drop down menu for Symbology.  In there, select "Symbolize your layer by quantities" -> "Graduated Colors"

Then from there, go to the Symbology tab on the left, and you can edit the field, normalization, classification method, number of classes, color scheme, etc.

And there's your map
Answer: You can perform a two step process where:

you convert your polygons to points (make sure you tick keep centriods in polygons option to make sure the centriods are always located within the polygons)
use either Kernel Density or the Hot Spot analysis function (Getis-Ord Gi*) which is nice as it gives you a statistical significance value to report.
Answer: FYI, Pro 1.2 allows a real, dynamic heat map for points.  Click your layer in the contents panel, select the appearances tab, click the symbology drop down and the option to heat map it should be there.
Answer: Two Tools let you make heat maps in ArcGIS : Point Density and Kernel Density. None take polygons as an input.
But you can get the same result with the Symbology of the polygon layer (Categories or Quantities).


Why do some Muslim Scholars require a woman to have permission to leave the country?

Question: I heard about one woman who convinced her family to go to Austria on a vacation but then left to go to Sweden. This woman was a Muslim woman from Saudi Arabia and tried to leave but needed the permission of a male. Does this go in accordance with what Islam says or is this kind of thing not right? Can someone please clarify this?
Comment: The permission thing depends on the tradition of the locality. Like here in India non-muslims also seek permission of gaurdian (male/female) if they want to go somewhere of stay late in friend's house
Answer: the prophet warned us that a women can not travel the distance of a one days travel without a mahram (man she cannot marry such as brother father uncle husband etc)

Sayyiduna Abu Huraira (Allah be pleased with him) narrates that the Messenger of Allah (Allah bless him & give him peace) said: "It is unlawful for a woman who believes in Allah and the last day that she travels the distance of one day and one night without a Mahram accompanying her." (Sahih al-Bukhari, no. 1038)

so not only does she need permission, she needs somone to accompany her too. the reason for this is because there may be danger in travelling alone. but if the distance is close enough she may go alone such as a supermarket or store.


Mêlée based, fantasy themed Warhammer 40k army?

Question: Which army is best suited to adapting to a fantasy themed, mêlée based army (in both rules and look of model)? Do 40k armies suit mêlée combat at all?
Comment: Orks or Chaos both lean towards melee combat and give you some leeway to dress them more in a "fantasy" way. I think mobility will start to be a major issue without vehicles and support fire, though, especially for larger army sizes.
Answer: Melee combat can be effective in 40k, but armies that focus on it to the exclusion of ranged combat will have serious issues.  Armies like Eldar rely on their shooting to reliably destroy tanks.
That being said many of the 40k armies have fantasy analogs, and most of the armies can field dedicated melee units.  Stylistically, armies like Grey Knights stay pretty close to their fantasy roots.  Chaos demons even use the same models between both games.
GW gamers all also very tolerant of themed conversions.  You can kit-bash Fantasy and 40k kits together to give a more sword and sorcery look to your grim dark.
Answer: Daemons of Chaos seems like an obvious answer here, since it's the same set of models for both game systems.  You would need to use the square bases to be playable in Fantasy, but the advantages that grants in 40K are pretty slim.  If you're not actively abusing it I doubt many people would object.  (Daemons are also frankly, not very powerful an army in 40K, so people are unlikely to cry cheese at you regardless.)


Coupling recharge with 1D groundwater flow model

Question: Suppose we are modeling 1D groundwater flow in an aquifer of extent $x$ from $A(x=0)$ to $C$. Lets say for unsteady state conditions, the input is at $A(x=0)$, we can model piezometeric response at $B (x>0)$ by heat equation. If I want to couple recharge from unstutrated zone into aquifer, should it be simply added to head value at $B$ or should it be implemented as boundary condition. Lets suppose we have already calculated recharge at point $B$ with Richard's equation.  I have tried to illustrate problem here. The problem is equivilant to 1D heat transport in a rod.
Comment: Doesn't it amount to the same thing? Adding to the head is the same as putting it in as a flux. Be sure you correct for the porosity when defining the change in head with recharge volume.
Answer: If you are not interested in the vertical flow occurring in your aquifer (which I assume is the case) then one can indeed add the recharge to the existing head!
In groundwater issues, we often assume the recharge to be constant over time and equal over distances when considering such problems. This is mainly due to simplification as we are often interested in horizontal flow rather than vertical flow.
That being said, in general I would consider recharge (as this seems to happen outside the system we are interested in) as a constant rather than a boundary condition.
However, when going into details, considering boundary conditions there are several ways to go:
Dirichlet boundary conditions: Where we assume a constant head at a certain location. As we go from A to B, we could assume constant heads at these location(s), depending on your setup.
Neumann boundary conditions: Where we assume a constant input/output discharge at a certain location. This could also be your recharge but also dependent on your setup.
Cauchy boundary conditions: complex combination of the two where the input is related to a head. An example of this could be a river with head h_x feeding an adjacent confined aquifer with head h_x2

I hope this gives some insight in the application of appropriate boundary conditions. As you can see: it all depends on the characteristics of the system, the known values and your own considerations.
For further reading one might consider Fitts' Groundwater Science (fully available at ScienceDirect)
Comment: Some more detail would improve this answer.


Natural question about weak convergence.

Question: Let $u_k, u \in H^{1}(\Omega)$ such that $u_k \rightharpoonup u$ (weak convergence) in $H^{1}(\Omega)$. Is true that $u_{k}^{+}\rightharpoonup u^{+}$ in $\{u\geqslant 0\}$? You can do hypothesis on $\Omega$ if you need.
Answer: I get the idea from Richard's answer.
Let $\Omega:=(0,2\pi)$ and $u_k(x):=\frac{\cos(kx)}{k+1}$. Then $\{u_k\}$ converges weakly to $0$ in $H^1(\Omega)$ (as it's bounded in $H^1(\Omega)$, and $\int_{\Omega}(u_k\varphi+u'_k\varphi')dx\to 0$ for all test function $\varphi$).
Assume that $\{u_k^+\}$ converges weakly to $0$ in $H^1(\Omega)$. Up to a subsequence, using the fact that $L^2(\Omega)$ is a Hilbert space, we can assume that $(v_k^+)'$ and $v_k^+$ converge weakly in $L^2(\Omega)$, where $v_k:=u_{n_k}$, respectively to $f$ and $g$. It's due to the fact that these sequences are bounded in $L^2$.
Then writing the definition $g'=f$. We also have $f=0$, hence (by connectedness of $\Omega$), $g$ is constant and should be equal to $0$.
But $$\int_{\Omega}|\sin(kx)|dx\geqslant \int_{\Omega}\sin^2(kx)dx=\pi,$$
and we should have that $2u_k^+-u=2u^+_k-u_k^++u_k^-=|u_k|$ weakly converge to $0$.


What is Rack middleware?

Question: What is Rack middleware in Ruby? I couldn't find any good explanation for what they mean by "middleware".
Comment: There is also a guide on RailsGuide now covering Rack comprehensively, including middleware: http://guides.rubyonrails.org/rails_on_rack.html
Comment: Thanks a lot to PhusionPassenger team, they have a well explained article on their blog. http://www.rubyraptor.org/how-we-made-raptor-up-to-4x-faster-than-unicorn-and-up-to-2x-faster-than-puma-torquebox/
Comment: Rack and rack middleware are explained in [THIS](https://medium.com/@shashwat12june/rack-and-rack-middleware-f93513ac92a6) article. Also explained about creating a rack based application.
Answer: Rack as Design
Rack middleware is more than "a way to filter a request and response" - it's an implementation of the pipeline design pattern for web servers using Rack.
It very cleanly separates out the different stages of processing a request - separation of concerns being a key goal of all well designed software products.
For example with Rack I can have separate stages of the pipeline doing:

Authentication: when the request arrives, are the users logon details correct? How do I validate this OAuth, HTTP Basic Authentication, name/password?

Authorization: "is the user authorised to perform this particular task?", i.e. role-based security.

Caching: have I processed this request already, can I return a cached result?

Decoration: how can I enhance the request to make downstream processing better?

Performance & Usage Monitoring: what stats can I get from the request and response?

Execution: actually handle the request and provide a response.

Being able to separate the different stages (and optionally include them) is a great help in developing well structured applications.
Community
There's also a great eco-system developing around Rack Middleware - you should be able to find pre-built rack components to do all of the steps above and more. See the Rack GitHub wiki for a list of middleware.
What's Middleware?
Middleware is a dreadful term which refers to any software component/library which assists with but is not directly involved in the execution of some task. Very common examples are logging, authentication and the other common, horizontal processing components. These tend to be the things that everyone needs across multiple applications but not too many people are interested (or should be) in building themselves.
More Information

The comment about it being a way to filter requests probably comes from the RailsCast episode 151: Rack Middleware screen cast.

Rack middleware evolved out of Rack and there is a great intro at Introduction to Rack middleware.

There's an intro to middleware on Wikipedia here.
Comment: Rack is part of your application so all middleware componets the same copy of the request and each can modify it in any way they want. AFAIK, there's no way to sandbox them the same way there's no way to sandbox one object from another within the same process (attempts at Ruby sandboxing notwithstanding).
Comment: I like to think of middleware as being anything that sits in the middle of my app between what I've coded and what goes to and from my server... which is hosted on rackspace. The reason the term 'rack middleware' is confusing, as we all know, is because it was Confucius that wrote all the original rack middleware, more than 2000 years ago. In France.
Comment: and Do understand Rack is different from Rake.
Comment: One thing I'm unclear on: do all the middleware share the same data?  Is it possible to separate them (i.e. sandbox one) for security?
Answer: First of all, Rack is exactly two things:

A webserver interface convention
A gem

Rack - The Webserver Interface
The very basics of rack is a simple convention. Every rack compliant webserver will always call a call method on an object you give him and serve the result of that method. Rack specifies exactly how this call method has to look like, and what it has to return. That's rack.
Let's give it a simple try. I'll use WEBrick as rack compliant webserver, but any of them will do. Let's create a simple web application that returns a JSON string. For this we'll create a file called config.ru. The config.ru will automatically be called by the rack gem's command rackup which will simply run the contents of the config.ru in a rack-compliant webserver. So let's add the following to the config.ru file:
class JSONServer
  def call(env)
    [200, {"Content-Type" => "application/json"}, ['{ "message" : "Hello!" }']]
  end
end

map '/hello.json' do
  run JSONServer.new
end

As the convention specifies our server has a method called call that accepts an environment hash and returns an array with the form [status, headers, body] for the webserver to serve. Let's try it out by simply calling rackup. A default rack compliant server, maybe WEBrick or Mongrel will start and immediately wait for requests to serve.
$ rackup
[2012-02-19 22:39:26] INFO  WEBrick 1.3.1
[2012-02-19 22:39:26] INFO  ruby 1.9.3 (2012-01-17) [x86_64-darwin11.2.0]
[2012-02-19 22:39:26] INFO  WEBrick::HTTPServer#start: pid=16121 port=9292

Let's test our new JSON server by either curling or visiting the url http://localhost:9292/hello.json and voila:
$ curl http://localhost:9292/hello.json
{ message: "Hello!" }

It works. Great! That's the basis for every web framework, be it Rails or Sinatra. At some point they implement a call method, work through all the framework code, and finally return a response in the typical [status, headers, body] form.
In Ruby on Rails for example the rack requests hits the ActionDispatch::Routing.Mapper class which looks like this:
module ActionDispatch
  module Routing
    class Mapper
      ...
      def initialize(app, constraints, request)
        @app, @constraints, @request = app, constraints, request
      end

      def matches?(env)
        req = @request.new(env)
        ...
        return true
      end

      def call(env)
        matches?(env) ? @app.call(env) : [ 404, {'X-Cascade' => 'pass'}, [] ]
      end
      ...
  end
end

So basically Rails checks, dependent on the env hash if any route matches. If so it passes the env hash on to the application to compute the response, otherwise it immediately responds with a 404. So any webserver that is is compliant with the rack interface convention, is able to serve a fully blown Rails application.
Middleware
Rack also supports the creation of middleware layers. They basically intercept a request, do something with it and pass it on. This is very useful for versatile tasks.
Let's say we want to add logging to our JSON server that also measures how long a request takes. We can simply create a middleware logger that does exactly this:
class RackLogger
  def initialize(app)
    @app = app
  end

  def call(env)
    @start = Time.now
    @status, @headers, @body = @app.call(env)
    @duration = ((Time.now - @start).to_f * 1000).round(2)

    puts "#{env['REQUEST_METHOD']} #{env['REQUEST_PATH']} - Took: #{@duration} ms"
    [@status, @headers, @body]
  end
end

When it gets created, it saves itself a copy of the actual rack application. In our case that's an instance of our JSONServer. Rack automatically calls the call method on the middleware and expects back a [status, headers, body] array, just like our JSONServer returns.
So in this middleware, the start point is taken, then the actual call to the JSONServer is made with @app.call(env), then the logger outputs the logging entry and finally returns the response as [@status, @headers, @body].
To make our little rackup.ru use this middleware, add a use RackLogger to it like this:
class JSONServer
  def call(env)
    [200, {"Content-Type" => "application/json"}, ['{ "message" : "Hello!" }']]
  end
end

class RackLogger
  def initialize(app)
    @app = app
  end

  def call(env)
    @start = Time.now
    @status, @headers, @body = @app.call(env)
    @duration = ((Time.now - @start).to_f * 1000).round(2)

    puts "#{env['REQUEST_METHOD']} #{env['REQUEST_PATH']} - Took: #{@duration} ms"
    [@status, @headers, @body]
  end
end

use RackLogger

map '/hello.json' do
  run JSONServer.new
end

Restart the server and voila, it outputs a log on every request. Rack allows you to add multiple middlewares that are called in the order they are added. It's just a great way to add functionality without changing the core of the rack application.
Rack - The Gem
Although rack - first of all - is a convention it also is a gem that provides great functionality. One of them we already used for our JSON server, the rackup command. But there's more! The rack gem provides little applications for lots of use cases, like serving static files or even whole directories. Let's see how we serve a simple file, for example a very basic HTML file located at htmls/index.html:
<!DOCTYPE HTML>

    <title>The Index</title>

Index Page

We maybe want to serve this file from the website root, so let's add the following to our config.ru:
map '/' do
  run Rack::File.new "htmls/index.html"
end

If we visit http://localhost:9292 we see our html file perfectly rendered. That's was easy, right?
Let's add a whole directory of javascript files by creating some javascript files under /javascripts and adding the following to the config.ru:
map '/javascripts' do
  run Rack::Directory.new "javascripts"
end

Restart the server and visit http://localhost:9292/javascript and you'll see a list of all javascript files you can include now straight from anywhere.
Comment: If you don't know what rack is, you'll know exactly what it is *and* how to use it after you read this blog post. Very nice. Ironically, though, the link to the official rack documentation at the end of the post is no longer available!
Comment: Your right, thanks. I included the contents into the post and removed the dead link.
Comment: I would say that it's not a convention. it's an interface, a contract well defined for a request-response model
Answer: I had a problem understanding Rack myself for a good amount of time. I only fully understood it after working on making this miniature Ruby web server myself. I've shared my learnings about Rack (in the form of a story) here on my blog: http://blog.gauravchande.com/what-is-rack-in-ruby-rails
Feedback is more than welcome.
Comment: [Link-only answers are discouraged on Stack Overflow](http://stackoverflow.com/help/how-to-answer), because if the resource the link goes to becomes unavailable in the future, the answer becomes useless. Please at least summarize the relevant points of your blog post and add them to this answer.
Comment: Thanks for you post. I'm a very beginner Rails programmer and I understood rack concept with your clear post.
Comment: Great blog post. The other answers seem a bit more convoluted IMO.
Comment: What an awesome explanation. Thanks, Gaurav.
Answer: What is Rack?
Rack provides a minimal interface between between webservers supporting Ruby and Ruby frameworks.
Using Rack you can write a Rack Application.
Rack will pass the Environment hash (a Hash, contained inside a HTTP request from a client, consisting of CGI-like headers) to your Rack Application which can use things contained in this hash to do whatever it wants.
What is a Rack Application?
To use Rack, you must provide an 'app' - an object that responds to the #call method with the Environment Hash as a parameter (typically defined as env). #call must return an Array of exactly three values:

the Status Code (eg '200'),
a Hash of Headers,
the Response Body (which must respond to the Ruby method, each).

You can write a Rack Application that returns such an array - this will be sent back to your client, by Rack, inside a Response (this will actually be an instance of the Class Rack::Response [click to go to docs]).
A Very Simple Rack Application:

gem install rack
Create a config.ru file - Rack knows to look for this.

We will create a tiny Rack Application that returns a Response (an instance of Rack::Response) who's Response Body is an array that contains a String: "Hello, World!".
We will fire up a local server using the command rackup.
When visiting the relevant port in our browser we will see "Hello, World!" rendered in the viewport.
#./message_app.rb
class MessageApp
  def call(env)
    [200, {}, ['Hello, World!']]
  end
end

#./config.ru
require_relative './message_app'

run MessageApp.new

Fire up a local server with rackup and visit localhost:9292 and you should see 'Hello, World!' rendered.
This is not a comprehensive explanation, but essentially what happens here is that the Client (the browser) sends a HTTP Request to Rack, via your local server, and Rack instantiates MessageApp and runs call, passing in the Environment Hash as a parameter into the method (the env argument).
Rack takes the return value (the array) and uses it to create an instance of Rack::Response and sends that back to the Client. The browser uses magic to print 'Hello, World!' to the screen.
Incidentally, if you want to see what the environment hash looks like, just put puts env underneath def call(env).
Minimal as it is, what you have written here is a Rack application!
Making a Rack Application interact with the Incoming Environment hash
In our little Rack app, we can interact with the env hash (see here for more about the Environment hash).
We will implement the ability for the user to input their own query string into the URL, hence, that string will be present in the HTTP request, encapsulated as a value in one of the key/value pairs of the Environment hash.
Our Rack app will access that query string from the Environment hash and send that back to the client (our browser, in this case) via the Body in the Response.
From the Rack docs on the Environment Hash:
"QUERY_STRING: The portion of the request URL that follows the ?, if any. May be empty, but is always required!"
#./message_app.rb
class MessageApp
  def call(env)
    message = env['QUERY_STRING']
    [200, {}, [message]]
  end
end

Now, rackup and visit localhost:9292?hello (?hello being the query string) and you should see 'hello' rendered in the viewport.
Rack Middleware
We will:

insert a piece of Rack Middleware into our codebase - a class: MessageSetter,
the Environment hash will hit this class first and will be passed in as a parameter: env,
MessageSetter will insert a 'MESSAGE' key into the env hash, its value being 'Hello, World!' if env['QUERY_STRING'] is empty; env['QUERY_STRING'] if not,
finally, it will return @app.call(env) - @app being the next app in the 'Stack': MessageApp.

First, the 'long-hand' version:
#./middleware/message_setter.rb
class MessageSetter
  def initialize(app)
    @app = app
  end

  def call(env)
    if env['QUERY_STRING'].empty?
      env['MESSAGE'] = 'Hello, World!'
    else
      env['MESSAGE'] = env['QUERY_STRING']
    end
    @app.call(env)
  end
end

#./message_app.rb (same as before)
class MessageApp
  def call(env)
    message = env['QUERY_STRING']
    [200, {}, [message]]
  end
end

#config.ru
require_relative './message_app'
require_relative './middleware/message_setter'

app = Rack::Builder.new do
  use MessageSetter
  run MessageApp.new
end

run app

From the Rack::Builder docs we see that Rack::Builder implements a small DSL to iteratively construct Rack applications. This basically means that you can build a 'Stack' consisting of one or more Middlewares and a 'bottom level' application to dispatch to. All requests going through to your bottom-level application will be first processed by your Middleware(s).
#use specifies middleware to use in a stack. It takes the middleware as an argument.
Rack Middleware must:

have a constructor that takes the next application in the stack as a parameter.
respond to the call method that takes the Environment hash as a parameter.

In our case, the 'Middleware' is MessageSetter, the 'constructor' is MessageSetter's initialize method, the 'next application' in the stack is MessageApp.
So here, because of what Rack::Builder does under the hood, the app argument of MessageSetter's initialize method is MessageApp.
(get your head around the above before moving on)
Therefore, each piece of Middleware essentially 'passes down' the existing Environment hash to the next application in the chain - so you have the opportunity to mutate that environment hash within the Middleware before passing it on to the next application in the stack.
#run takes an argument that is an object that responds to #call and returns a Rack Response (an instance of Rack::Response).
Conclusions
Using Rack::Builder you can construct chains of Middlewares and any request to your application will be processed by each Middleware in turn before finally being processed by the final piece in the stack (in our case, MessageApp). This is extremely useful because it separates-out different stages of processing requests. In terms of 'separation of concerns', it couldn't be much cleaner!
You can construct a 'request pipeline' consisting of several Middlewares that deal with things such as:

Authentication
Authorisation
Caching
Decoration
Performance & Usage Monitoring
Execution (actually handle the request and provide a response)

(above bullet points from another answer on this thread)
You will often see this in professional Sinatra applications. Sinatra uses Rack! See here for the definition of what Sinatra IS!
As a final note, our config.ru can be written in a short-hand style, producing exactly the same functionality (and this is what you'll typically see):
require_relative './message_app'
require_relative './middleware/message_setter'

use MessageSetter
run MessageApp.new

And to show more explicitly what MessageApp is doing, here is its 'long-hand' version that explicitly shows that #call is creating a new instance of Rack::Response, with the required three arguments.
class MessageApp
  def call(env)
    Rack::Response.new([env['MESSAGE']], 200, {})
  end
end

Useful links

Complete code for this post (Github repo commit)
Good Blog Post, "Introduction to Rack Middleware"
Some good Rack documentation
Comment: Thank you very much for the detailed explanation.
Comment: haha thanks @ThomasDeranek ! I have to admit I've sometimes wondered why it's not had more upvotes lol
Answer:
Rack is a gem which provides a simple interface to abstract HTTP request/response. Rack sits between web frameworks (Rails, Sinatra etc) and web servers (unicorn, puma) as an adaptor. From above image this keeps unicorn server completely independent from knowing about rails and rails doesn't know about unicorn. This is a good example of loose coupling, separation of concerns.
Above image is from this rails conference talk on rack https://youtu.be/3PnUV9QzB0g I recommend watching it for deeper understanding.
Answer: config.ru minimal runnable example
app = Proc.new do |env|
  [
    200,
    {
      'Content-Type' => 'text/plain'
    },
    ["main\n"]
  ]
end

class Middleware
  def initialize(app)
    @app = app
  end

  def call(env)
    @status, @headers, @body = @app.call(env)
    [@status, @headers, @body << "Middleware\n"]
  end
end

use(Middleware)

run(app)

Run rackup and visit localhost:9292. The output is:
main
Middleware

So it is clear that the Middleware wraps and calls the main app. Therefore it is able to pre-process the request, and post-process the response in any way.
As explained at: http://guides.rubyonrails.org/rails_on_rack.html#action-dispatcher-middleware-stack ,  Rails uses Rack middlewares for a lot of it's functionality, and you can add you own too with config.middleware.use family methods.
The advantage of implementing functionality in a middleware is that you can reuse it on any Rack framework, thus all major Ruby ones, and not just Rails.
Answer: Rack middleware is a way to filter a request and response coming into your application. A middleware component sits between the client and the server, processing inbound requests and outbound responses, but it's more than interface that can be used to talk to web server. It's used to group and order modules, which are usually Ruby classes, and specify dependency between them.  Rack middleware module must only: – have constructor that takes next application in stack as parameter – respond to "call" method, that takes environment hash as a parameter. Returning value from this call is an array of: status code, environment hash and response body.
Answer: I've used Rack middleware to solve a couple problems:

Catching JSON parse errors with custom Rack middleware and returning nicely formatted error messages when client submits busted JSON
Content Compression via Rack::Deflater

It afforded pretty elegant fixes in both cases.
Comment: This answer, while somewhat useful, does not actually address the question of ***what Rack Middleware is***.
Comment: Also this one is fairly link-only answer... :P
Answer: Rack - The Interface b/w Web & App Server
Rack is a Ruby package which provides an interface for a web server to communicate with the application. It is easy to add middleware components between the web server and the app to modify the way your request/response behaves. The middleware component sits between the client and the server, processing inbound requests and outbound responses.
In layman words, It is basically just a set of guidelines for how a server and a Rails app (or any other Ruby web app) should talk to each other.
To use Rack, provide an "app": an object that responds to the call method, taking the environment hash as a parameter, and returning an Array with three elements:

The HTTP response code
A Hash of headers
The response body, which must respond to each request.

For more explanation, you can follow the below links.
1. https://rack.github.io/
2. https://redpanthers.co/rack-middleware/
3. https://blog.engineyard.com/2015/understanding-rack-apps-and-middleware
4. https://guides.rubyonrails.org/rails_on_rack.html#resources

In rails, we have config.ru as a rack file, you can run any rack file with rackup command. And the default port for this is 9292. To test this, you can simply run rackup in your rails directory and see the result. You can also assign port on which you want to run it. Command to run rack file on any specific port is
rackup -p PORT_NUMBER

What is Rack middleware?


Who authored the Tanach?

Question: According to traditional Jewish thought, who authored the twenty-four books of the Tanach?
Comment: related: https://judaism.stackexchange.com/q/83118/16354
Comment: Hi user50746, and [welcome to Mi Yodeya](https://judaism.meta.stackexchange.com/questions/3886/a-beginner-s-guide-to-my-how-is-this-site-different-from-other-judaism-sites/3887#3887). I've edited your question a bit to make it fit the site better. Also, on this website you will by default recieve a traditional Jewish answer, as that is what this site is for.
Answer: According to the Talmud (Bava Basra 14b-15a), the authors were the following (order based on the Gemara there):

Torah (Pentateuch) - Moshe (Perhaps Yehoshua wrote the last 8 Pesukim)
Yehoshua (Joshua) - Yehoshua (Finished by Elazar Ben Aharon and Pinchas)
Shoftim (Judges) - Shemuel
Shemuel (Samuel) - Shemuel (Finished by Gad Hachozeh and Nasan Hanavi)
Melachim (Kings) - Yirmiyah
Yirmiyah (Jeremiah) - Yirmiyah
Yechezkel (Ezekiel) - Anshei Kenesses Hagedolah
Yeshaya (Isaiah) - Chizkiyah et al.
Sheneim Asar (12 Minor Prophets) - Anshei Kenesses Hagedolah
Rus (Ruth) - Shemuel
Tehillim (Psalms) - David and various prior authors ("10 Elders")
Iyov (Job) - Moshe
Mishlei (Proverbs) - Chizkiyah et al.
Koheles (Ecclesiastes) - Chizkiyah et al.
Shir Hashirim (Song of Songs) - Chizkiyah et al.
Eichah (Lamentations) - Yirmiyah
Daniel - Anshei Kenesses Hagedolah
Esther - Anshei Kenesses Hagedolah
Ezra - Ezra
Divrei Hayamim (Chronicles) - Ezra and Nechemia
(Nechemia (Nehemiah) - Nechemia)

Note that these attributions are not absolute in the Jewish tradition, and there are various other (acceptable) opinions.  For some further reading about this I would suggest Abarbanel's Introduction to Yehoshua, where he discusses this Talmudic passage at length.  See also the Rishonim and Acharonim on this Gemara, which refine some of the Gemara's statements (e.g. what Chizkiyah actually wrote).
Comment: Slight amendment to who wrote the Torah - There's a dispute regarding the last parsha about Moshe's death. Some say it was Yehoshu'a, some say it was Moshe. Similar ideas would occur with verses that seem out of place, for example, the 2nd to last verse in *parshat hamahn* (manna) that mentions that they ate the mahn for 40 years. That could not have been written by Moshe exactly at the time that the mahn first fell.
Comment: Re - Shmuel writing his own book - How is that possible considering that the majority of both books mention events occurring after his death? Re Mishlei, Kohellet and Shir Hashirim - I thought they were all written by Shlomo (King Solomon). Esther - not written by Mordechai and Esther?
Comment: @DanF feel free to edit in the "final 8 Pesukim" comment (if I don't first...).  However, even if you are correct about the other Pesukim (which is very likely), Chazal don't say that here, and I would consider alternate authorship of those not "traditional Jewish thought".  Re: the other authors of those books, I'll try to edit now based on the continuation of the Gemara, which takes some of your points into account
Comment: @DanF for Mishlei, Koheles, Shir Hashirim, and Esther, they all seem to be narrations of what happened/had been said by the people you mentioned, which could mean that the content was from earlier, but was rewritten somewhat by those later authors (Anshei Knh"G/Chizkiyah Vesa'yaso).
Comment: While this source is certainly the most famous one in "the velt", it is a) not really an accurate answer regarding _authorship_, more like redaction b) doesn't take the rest of the gemara into account, and c) isn't even universally agreed upon. I can't vote this up. It's almost misleading sitting here unqualified.
Comment: @DoubleAA fair indeed.  Being that it's "the most famous one in the velt", I felt it was a fair answer to the OP.  Feel free to add an answer that includes some of the Shitos of the various Rishonim and Acharonim on this.  No need to upvote it, in fact, feel free to downvote.
Comment: @DoubleAA do you like the disclaimer?
Answer: The Babylonian Talmud (Bava Batra 14b, 15a) informs us who wrote each book in the Tanach.
You can refer to both the Talmudic citations I've linked to or this handy chart I made.
Comment: While this source is certainly the most famous one in "the velt", it is a) not really an accurate answer regarding _authorship_, more like redaction b) doesn't take the rest of the gemara into account, and c) isn't even universally agreed upon. I can't vote this up. It's almost misleading sitting here unqualified.

Who authored the Tanach?


Why are perfect graphs called perfect?

Question: Sorry, if this is a naive question, but I could not find the justification in any of the major text books like Bondy-Murty, Diestel or West. Perfect graphs have many beautiful properties, but what is the single reason they are called perfect? Or is it just a aesthetic preference by Berge?
Comment: The meaning is exactly the same in our language as in yours.
Comment: Presumably, he originally called them *parfait* and not *perfect.* It does mean almost the same thing. Possibly some French speaker here could tell us whether *parfait* in French is slightly less absolute in meaning than *perfect* in English.
Answer: perfect graphs were first motivated by information transmission theory originating with Shannon ie Shannon Capacity of graphs. they are called "perfect" by Berge because they can be used to model a noiseless or "perfect" information channel wrt transposition errors in transmission called "confounding". from intro in [3] which also has a very detailed history in the 1st chapter cowritten by Berge.

When Claude Berge defined perfect graphs in 1961, he was motivated by a very practical problem: how do we maximize the rate at which information is sent through a (noisy) transmission channel while avoiding the introduction of errors because of the physical imperfections of the system?

[1] C. Berge, The history of the perfect graphs, Southeast Asian Bull. Math.
20, No.1 (1996) 5-10.
[2] C. Berge, Motivations and history of some of my conjectures, Discrete Mathematics
165-166 (1997) 61-70.
[3] Perfect Graphs by Jorge L. Ramírez-Alfonsín (Editor), Bruce A. Reed (Editor), J.L.R. Alfonsin (Author). Wiley. Ch1, Origins and Genesis by Berge & Ramírez-Alfonsín
Comment: I suspect this answer could use more explanation. For perfect graphs, the single-symbol zero-error capacity (encoding the information without using block codes) is equal to the asymptotic zero-error capacity. Thus, you can easily calculate the zero-error capacity, and it is obtainable using the simplest possible code. One of Lovász's [celebrated results](http://en.wikipedia.org/wiki/Lovász_number) was calculating this capacity for the five-cycle, the simplest non-perfect graph. And unless progress has been made in the last couple of years, we still don't know what it is for the seven-cycle.
Comment: I like the succinctness of the answer, in conjunction with the citations.  This is a topic on the periphery for me, and this short answer is quite useful as an intro to a complex subject.

Why are perfect graphs called perfect?


How do I improve head retention?

Question: Just opened a bottle conditioned "Belgian Black"-- delicious and well carbed.
However, there is little no head on the pour and the lacing is pretty weak, too.
How do I ensure good head retention?
Comment: This would be a good case to post the recipe and process as part of your question too.
Answer: The first place I always start with head retention is glassware.  If your cleaned you glass with any type of detergent, especially in a dish washer; a head-negative residue can be left behind on the glass.  To really rule this out I'd soak the glass in some warm/hot PBW (or other non-detergent cleaner).  Then rinse really well with warm water.  Finish with a quick rinse in cool water to chill the glass down some, then pour right away into the wet glass.
Seeing how you came from a bottle too, I'd also mention that you should be careful to use non-detergent cleaners on your bottles too.
Your water chemistry can have an impact, but slight.  The next steps I'd take are dependent upon whether you are brewing extract or all grain.  Are there any extra head-positive malts in your recipe.  The amount of hop oils can reduce head.  Lastly, perfect yeast health promotes head by limiting the amount of dead yeast that was added at pitching.  Dead yeast give off lipids with will break down head.
There was an entire episode devoted to head retention on BrewStrong at the Brewing Network.
Comment: Lots of hop oils will ADD to your lacing though. My IPAs always have fantastic lacing. +1 on the glassware suggestion.

How do I improve head retention?


How to let search engines index form-locked PDFs

Question: I'm using download manager, that locks the downloading of PDF until the user fills out a lead form. But the data in PDF is valuable and should be indexed by search engines. Any idea how can I achieve it?
Answer: One way this could be done is through PHP user agent:
<code>if(strstr(strtolower($_SERVER['HTTP_USER_AGENT']), "googlebot"))
{
    // what to do
}
</code>
If the user is Googlebot, display/redirect to the PDF file. If the user isn't Googlebot, show them the submission form to receive the PDF file.
However, it's worth noting that Google wants to know what you are showing its users. If it thinks you're linking to a PDF file but you're really serving up a form first it might not like that.
But detecting the user agent to determine if you're going to show the PDF or the submission form is probably the only way to accomplish what you're trying to do.
Comment: Allow Googlebot to access content that you hide from users is the definition of [cloaking](https://support.google.com/webmasters/answer/66355?hl=en) and doing so is likely to get your site banned from appearing in Google.


Are there ways to have a functioning editing workflow in Wordpress?

Question: The Cooking blog has two admins (I am one of them) and lots of contributors. A contributor writes a post, then the first admin edits it, then the second admin edits it, then we two admins talk about possible differences (contradictory comments turned out to confuse the author :P) then it goes back to the original author, who is supposed to implement, accept or reject our edit suggestions (which can be changes directly in the text, or comments describing what is wrong). The whole cycle is repeated 2-3 times until a post is finalized. We have found no way to do this in Wordpress.
Currently, we receive the draft in a format the contributor finds convenient (directly in Wordpress, as a .doc file, in an email body, shared in Google docs). The only tool we have which has a "track changes" functionality is a full-blown word processor, so we copy it there and return it that way to the contributor. When the editing process is finalized, we transfer the text to Wordpress, manually adjusting all the formatting. This is a time-intensive process, and in the end it can happen that the contributor is unhappy with some formatting details, so they have to go over the post again and ask us to change it.
During this process, everybody has to actively message the others that he has just made some changes and it is "their turn". This is failure-prone, as we have had cases where two people were editing in parallel without noticing, and cases where a planned task didn't get done because everybody thought somebody else is currently doing it. Besides, for longer-term posts we forget at which stage they are/whose "turn" it is and have to search through chat transcripts and hope that the message we have found reflects the current situation.
A perfect solution would allow us to move the whole workflow to WordPress. Specifically, we need:

a "track changes" function
a function for leaving comments related to a specific place in the text
a system for tracking the current "status" of a blog. In a perfect world, that would include a custom list of stati, such as "waiting for edit by rumtscho", but even a cruder system ("waiting for a review by and editor") would be better than nothing.
active messaging which automatically notifies everybody associated with the post of a change in status, for example by sending an email. (Not something which is visible only when that person is logged in, because this is a side project for all of us and we don't visit the dashboard often).
a schedule. Not just the simple "schedule for publishing on $date" thing for posts, but a calender accessible to authors and contributors, where events can be linked to existing posts and drafts.

It is probably wishful thinking to hope that all of this will be present in some way. But are there solutions which at least come close in some way, or which offer other good ways to solve our problems and create a working process out of this chaos?
Answer: Search the Repository for the Edit Flow plugin. It does exactly what you're looking for and then some.
Comment: http://wordpress.org/extend/plugins/edit-flow/
Comment: Single line answers as well as link only answers are considered poor quality. Please improve your answer.
Comment: Trying to be sarcastic at all, but what should I have added? (I'm new here). That plugin really does do everything the OP needs to do. I didn't think there was a need to go on and on when it's that simple.


How to fix Feature with Panels

Question: I am managing a website that makes extensive use of panels. I had a "system" panel page with Title = 'Registration Template' and a path of 'registration/%registration'.
Somehow, in updating the features on the LIVE site, I managed to loose this panel page. It is not available on the LIVE site. I can recreate a feature with "registration_view_panel_context" this under Page Manager.
But when I move this feature to the live site, it does not become available to me as a panel. It is included in the feature, but the feature is overridden. I am unable to "revert" the feature.

Despite being labeled as a "system" page, the 'Registration Template' is not available to me.
As a "system" page, I do not have the option of exporting it from my local site.
And when I try to revert the feature on LIVE - nothing happens.
If I try to create a new panel page on LIVE with this path - "registration/%registration" I get a message "that path is already in use. This system cannot override existing paths."

This panel page is still available to me and works on my local site, but I can't figure out how to move it back onto the LIVE site.
Any ideas?
EDIT: Solved this problem myself (not myself, but with local help :-)
See below for answer.
Comment: It turns out I needed to recreate this "system" page as an "existing page" using the - Page Manager Existing Pages - module (https://www.drupal.org/project/pm_existing_pages). I am not entirely sure why, but this solved my problem.
Answer: It turns out I needed to recreate this "system" page as an "existing page" using the - Page Manager Existing Pages - module (drupal.org/project/pm_existing_pages). I am not entirely sure why, but this solved my problem.

How to fix Feature with Panels


Capitalization of job title

Question: Would you capitalize the job title in the following sentence?

I am writing this letter in regard to Joe Brown who is applying for the director of teaching and learning position in the XYZ School District.
Answer: The Chicago Manual of Style says not to capitalize a title when it appears alone like that. Nor should you cap it when it appears in apposition, such as (if your candidate gets the job),

Joe Brown, director of teaching and learning

You cap formal titles when they appear before someone's name,

Director Joe Brown

though not every title is meant to be used in that way... for instance, if you were talking about Steven Spielberg, in most contexts you would say

director Steven Spielberg

because in most contexts you wouldn't be ascribing a formal title to him, but merely describing what he does.
Answer: The rule is that when a title immediately precedes the name, e.g. "Director Joe Brown," then the job title is capitalized, but not when it comes afterwards.  See, e.g., GPO Style Manual § 3.34.  Exceptions are made for especially important positions like President of the United States or Queen of England.  Ibid. § 3.35.  The GPO Style Manual gives the example:  "Charles F. Hughes, rear admiral, U.S. Navy: the rear admiral."  In your sentence, Mr. Brown doesn't even have the job, so director would be lower case.

Capitalization of job title


When shooting one-on-one with a subject, what are some tips and tricks to get into a "photoshoot" mood?

Question: When it's just you and a subject shooting by yourselves, what tips and tricks are there to keep the mood light and friendly, while simultaneously controlling and directing the subject into good poses? The subject does not have modeling or photography experience, and the environment could be outdoors or indoors in a studio (doesn't matter).
Answer: Well, one can write an entire book on this. Also there isn't a definitive answer. But, as you say, here are some "tips and tricks":

make it clear that you're on "their side". That you're helping them to make the shoot good.
arrange a little their clothes, their hair, take an invisible piece of dirt (it doesn't need to really exist) from their clothes - this helps to break the distance between you and them
talk to them. Make them speak. Jokes. This will help them to be natural.
praise them. Say 'Wow!', 'Great!', 'Very good!' etc.
do play with them. Make them play.
put music. Good music. (Well, what means 'good music', this is another story...)
say to them "I'll take now some shoots but don't be afraid, I just check the settings, camera, metering etc. I will take the official shots latter". This will make them more relaxed.
give them indications but don't tell them too much how to pose. Rather show them by your example (your body, hands, facial expression etc.)
give them something in their hands or show them how to keep them. Usually people doesn't know what to do with their hands.
take great care to not be 'boring'. Neither you, neither your session.
be innovative. Try to push the envelope on some shots (even if they'll be thrown away - you'll see that these will be one of the best) just in order to keep the things 'interesting', 'fun' etc.
have your attention focused on your subject's mood. He is the most important thing, not the camera
smile. be professional.
be humble.
Comment: Wow, these are all great tips, exactly what I was looking for. Thanks!
Answer: Nice work, John Thomas. I add only a few:

Offer them a tea before starting the actual shooting. Or just sit down a bit with them. Or just show them around. Do not jump into the shooting directly.
Offer them water to drink during shooting. Dehydration will show up on your pictures as the model will get uneasy, will feel tired, exhausted. Do not do this excessively though, as you will face other discomfort and lots of bathroom breaks... :-)
Have a sense when your model wants you to talk more or less. If you do not get the right balance, you will screw up the mood.
Give them an instrument . They can kind of "hide behind" without actually hiding, and they will feel more comfortable. Same goes with clothes that are loose and cover them considerably.
Get a friend of the model be present and yourself be transparent.
This is a different approach, but works great with kids, insecure
people, and if you are insecure yourself, it will help you too to get
more practice, and become knowledgeable of the action, your tools and
get more control over what is happening.
Handle a pro like a pro. They have been studying poses for ages for themselves and figured out transitions between them. Do not pose a pro if you do not know how to pose! Neither pose a natural talent. You will piss them off, or will make them uncomfortable. Go with the flow, be very alert, shoot a billion, and you will have very nice pictures.
In general, if you do not know model work, use a studio where you can shoot in bursts (the flash heads support it). You will have higher chance to capture a great photo. Do not do long bursts though as the face expression will get tense or the eyes watery.

Good luck!