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July 4

Drone bees

Can someone help me understand the role of drone bees please? I thought that the only egg-laying bee is the Queen bee and her fertilised eggs become Worker bees and the unfertilised eggs become Drone bees. Since Drone bees fertilise the Queen bee's eggs, why aren't all resulting bees genetically identical since both sets of genes come from the queen bee (as the drone bee is from the QB's unfertliised egg)? I read that there are sometimes laying worker bees but this is only in the absence of a queen bee. Thank you — Preceding unsigned comment added by 81.91.232.122 (talk) 01:57, 4 July 2014 (UTC)

There's a good discussion here: [1]. Look for the "4.1. Genetic explanations" section. My reading is that the drones have half the queen's genes, and the queen also contributes half of her genes when mating, but these halves can include overlapping genes, and miss other genes. So, the workers each get a different set of duplicates and missing genes, making them slightly different genetically.

What I'm unclear on is how the next queen gets her genes. Is she a clone of the old queen ? If so, how is this accomplished ? StuRat (talk) 02:40, 4 July 2014 (UTC)

"My reading is that the drones have half the queen's genes"

So each of the unfertilised eggs if the queen bee are genetically distinct as they divide in half differently? And some genes are missing entirely in worker bees? Didn't realise that was possible. Do you have any more sources I can use? — Preceding unsigned comment added by 81.91.232.122 (talk) 02:55, 4 July 2014 (UTC)

Yea, you'd expect that the absence of some genes would be fatal. Perhaps they do have a high defect rate and just lay more eggs to compensate, killing off any worker that manages to hatch, but is obviously defective. They might also have many copies of critical genes on different chromosomes, to increase the likelihood that at least one will be passed on to each worker. If there's only one copy of a gene, there should be a 25% chance it will be missing, while, if there were 10 copies, each on a different chromosome, that chance drops to less than one in a million, ignoring mutations, etc. StuRat (talk) 03:16, 4 July 2014 (UTC)

I don't know what the heck you're talking about here, but there is no random gene loss. You could think of the drone as being a sperm, in the sense that it is already haploid, but it doesn't cut that down further. See haplodiploidy. Wnt (talk) 03:21, 4 July 2014 (UTC)

Oh, I see the problem. I was assuming from my reading of that site that the drones mate with their own mother (the queen), but this apparently isn't normally the case. Inbreeding, can, of course, lead to a loss of genetic diversity. StuRat (talk) 15:38, 4 July 2014 (UTC)

I think Stu is trying to get at recombination. In honey bees, when the queen lays a fertilized egg, the results are not clones, but because of haplodiploidy, they share 75% of alleles on average. When she lays an unfertilized egg, they become males, but these share only 50% of their alleles on average. In honey bees, queen determination is solely a developmental pathway, genetics have nothing to do with it. Proto-queens are just fertilized eggs layed in a special larger cell (queen cell), and fed with more royal jelly. In a laboratory setting, we can make any fertilized bee egg into a queen. Note that this is not a general rule though, in e.g. the Melipona and some other bees, there is genetic caste determination (redlink, I mean genetic control of caste_(biology), see a paper on how this work in some ants here [2]), though that is a more recent finding and less well understood. SemanticMantis (talk) 15:41, 4 July 2014 (UTC)

Lovers' lanes. Secluded, south-facing lovers' lanes, it would appear, at least in Puerto Rico, with bees commuting 500 m to 5 km to get there from hundreds of hives. The magic word is "drone congregation areas". See [3] and especially [4] for more about them. Thanks for asking this!!! Wnt (talk) 02:56, 4 July 2014 (UTC)

(Ha, this reminds me in grad school, there was a secluded road by the ag research farms called Bee Biology road. It was often used by humans as a "lovers' lane." Something about birds and bees I guess...) SemanticMantis (talk) 15:03, 4 July 2014 (UTC)

I think you've got your answers already; it's all about haplodiploidy. Also note that while technically possible, it is not the norm for a queen to mate with her own drone. See nuptial flight. Also, in honeybees, virgin queens can mate with many drones in one flight. 10-15 separate inseminations is not uncommon if I recall correctly. I also want to point out that among the bees there are very different colonial systems. In Apis mellifera, male drones are basically flying sperm that don't do much of anything other than mate and die. In some sweat bees and some solitary bees however, males life roughly as long as the female and in some cases help with provisioning offspring. Incidentally, haplodiploidy is seen as a key feature for allowing Evolution_of_eusociality in the worker castes of the eusocial hymenoptera. The idea is, sister workers share 75% of their alleles with each other, while their hypothetical offspring would only share 50% on average. Kin selection is widely accepted as an explanation for this process, but the analogous group selection is somewhat more contentious. SemanticMantis (talk) 14:59, 4 July 2014 (UTC)

Species

What's the definition of a species? 24.5.122.13 (talk) 05:28, 4 July 2014 (UTC)

See Species. HiLo48 (talk) 05:37, 4 July 2014 (UTC)

So would the spinner dolphin and the striped dolphin be considered two separate species, or two subspecies of one species, along with their hybrid the Clymene dolphin??? 24.5.122.13 (talk) 08:02, 4 July 2014 (UTC)

See Species problem. The more we study these things the more we realise that "species" is a human cultural concept, with limited application to reality. That's why cladistics is becoming the preferred method of biological classification. Rojomoke (talk) 12:42, 4 July 2014 (UTC)

It's the borderlines that cause the classification problem. This is one example. Some things called hybrids aren't really hybrids. However, you can't easily mate a dolphin with a horse, for example. Those are clearly separate species. ←Baseball Bugs ^{What's up, Doc?} carrots→ 14:41, 4 July 2014 (UTC)

• See biological species concept. There are instances as in Europe where two neighboring species such as the Hooded Crow and Carrion Crow overlap in a narrow band, and hybridization occurs. The hybrids, while fertile, do not seem to fare as well as the pure species and backbreeding into the general populations is not significant enough to cause a wide transitional area of confusion among the main types. This is also common with oaks, where many species are specialized for habitat. A species specialized for humid valleys and on for dry hilltops can interbreed with fertile offspring, but the hybrids do not do as well in valleys or on mountainsides as the parent species, so the difference is maintained. The fact that there are transitional forms in no way invalidates the usefulness of the concepts as tools, when used properly. One can even clean one's earwax with a phillip's head. μηδείς (talk) 20:48, 4 July 2014 (UTC)

Job prospects

If it took 2 years longer to get a degree due to repeat years as a result of failed exams, your grades were only average and you filled the gaps with voluntary work or work in industry, how likely is that to affect your future career? — Preceding unsigned comment added by 94.10.247.171 (talk) 09:34, 4 July 2014 (UTC)

There are pro's and con's. Failed exams and repeat years isn't good - but time spent in industry and in voluntary work are a plus. I can't speak for every field - but in mine (Computer science) we probably wouldn't even ask about the reason for the extra time - probably we'd be more interested in what you did when you were "working in industry". When you get a fresh graduate with zero work experience, you always wonder how they'll adapt from easy-going college hours to a 9 to 5 job, how they'll work in a team, and how they'll cope when they are handed a project that they must complete by some deadline. Having worked in a "real job" (ideally in your field of future employment) is a huge win because it is concrete confirmation that you know what it's like to be in a 9-5 job.

You don't have to say why you took longer to get your degree on your resume and I doubt most employers would ask. But you might want to be ready with some well-thought out answers to that question. "I felt the need to dive more deeply into the subject matter" or something like that.

You also mention "your future career" - presumably beyond your first job until retirement. Again, I can only speak for my industry - but generally, your degree is what gets you your first job. Your first job is what gets your your second job and so on. The things you worked on most recently are by far more interesting than what you did 5, 10 or 20 years ago. This is especially noticeable for people with advanced degrees - masters and PhD's - for those people, it's a massive benefit for getting their first job. It matters less for their second - and after they've been out working for 20 years, recruiters may not even read that far back down their resume!

So I don't think this should affect you too badly. Certainly it mustn't affect your confidence in going into those first interviews. Make much of what you learned in your industry jobs - explain the responsibility that came with your volunteer work - how you enjoyed working in a team environment - your sense of achievement at pulling off something "real"...that kind of thing.

SteveBaker (talk) 12:10, 4 July 2014 (UTC)

Normally you'd just put your year of graduation on your resume, along with what degree or diploma you ended up with. You're not likely to be asked how long it took you to reach it. 173.228.123.145 (talk) 23:04, 4 July 2014 (UTC)

That's true - but a very late graduation might lead them to ask what you did in the years between high school and college. Gaps in a resume are usually considered significant because they can indicate period of unemployment or even prison terms. However, with the time spent working in industry and in volunteer activities, explaining away such a gap shouldn't be a problem here. SteveBaker (talk) 14:35, 6 July 2014 (UTC)

In my job hunt after graduating I customized each resume to list classes that would apply to the specific job, along with details of what subjects/projects from those classes seemed to make then a good experience. During the interview process for my current job they told me they were impressed by me putting those details into the resume, so simply listing a degree and date might not be the best idea. We request transcripts here, so bad grades would show up too. I had a rough start in college but it was clear from my transcripts that I got back on track and finished with my last few years being very strong, so they weren't concerned. Katie R (talk) 15:35, 7 July 2014 (UTC)

orang - chimp - human image origin

What is the origin of this much-parodied image on human evolution? Image:Human-evolution-man.png ---- CS Miller (talk) 12:32, 4 July 2014 (UTC)

See March of Progress. The original was drawn by Rudolph Zallinger, and first appeared in a book of the Life Nature Library series in 1965. Tevildo (talk) 13:15, 4 July 2014 (UTC)

Resolved

Thank you, Tevildo. CS Miller (talk) 14:22, 5 July 2014 (UTC)

DIS1

Dear Sirs,

Do you know what "DIS1" means? I know it is a microtubule-associated protein, but I do not know what it means, from what words it is composed. It is similar as TOG (tumor overexpressing gene), but I do not know from what words it is composed. I think that it is a TOG of the S. pombe.

Yours sincerely,

Đekić Miloš

Serbia — Preceding unsigned comment added by 109.93.106.27 (talk) 14:48, 4 July 2014 (UTC)

Possibly "defect in sister chromatid disjoining", as per this, which I found by googling "dis1". ←Baseball Bugs ^{What's up, Doc?} carrots→ 15:06, 4 July 2014 (UTC)

Yup, I got http://www.pombase.org/spombe/result/SPCC736.14 , but don't know anything of the area to make anything of it. CS Miller (talk) 15:38, 4 July 2014 (UTC)

Sister chromatid separation is defined here. הסרפד (call me Hasirpad) 15:57, 4 July 2014 (UTC)

Is there such a thing as leaf toner?

There is a plant hormone marketed as root toner which induces the growth of roots on plant cuttings.

Is there a parallel hormone which will induce the growth of leaves on (presumably wounded) living hardwood branches that lack leaves?

I have a holly which had to have some branch ends removed. One sprouted new leaves, the other didn't.

Searches of google pretty much return only skin toner for women based on plant leaf hormone extracts.

Thanks. μηδείς (talk) 20:06, 4 July 2014 (UTC)

You'll want to consult an actual expert in person who can answer your questions more directly, but this site recommends a high nitrogen fertilizer. --Jayron32 20:42, 4 July 2014 (UTC)

1. I don't think there's a widely available commercial product like that.
2. You may be able to get your hands on some auxin or Gibberellic_acid, pasting some of that on the tips might help. (Oops, you want to not use auxin, that's what suppresses buds).
3. If you have access to any willow cuttings, (Salix spp.), you can make up a nice little batch of plant hormones in the following way: take several pencil-diameter cuttings, about 12" long (smaller or bigger is ok). Put in a small-mouth bottle to prevent evaporation, fill with water, and place in location with fairly bright indirect light. After a few weeks, you should see vigorous root growth and some bud formation. Grind up the buds and bark in the water, soak for another day, and use that to make a paste with some peat moss or leaf mulch. This paste will contain decent amounts of jasmonic acid, salycylic acid, and a few others. It can help other plants root and bud (I have not personally tested the latter).
4. You can also work with the plant's natural hormonal system. Apical meristems suppress the formation of other meristems, and each of those ultimately comes from stem cells, sometimes in a structure like an epicormic bud. Think of how, for many plants, a single pruning will be followed by two or more buds emerging near that tip. The the tip sends "no bud" signals to the rest of the plant, and when that signal is removed, buds form. So, you can induce bud growth on one branch by removing many bud tips/meristems from the other branch. You don't even need to remove many leaves if you don't want to, as long as the tips are taken off. This can process take some time, and may require subsequent pruning of the productive branch. If it's only been a few weeks since pruning, I'd just wait a bit more before I did much of anything.
5. Good luck! (post EC with Jayron, a little fertilizer couldn't hurt, but I'd personally go for a milder N level than a stronger one.) SemanticMantis (talk) 20:46, 4 July 2014 (UTC)

Thanks, guys, I actually did growth experiments in high school biochemistry and one of my undergrad majors was plant ecology.

What has happened is a holly in my father's back yard was losing half its leaves to yellow blight every year, to the point where it would soon be dead. The google solution was to remove the lower branches to improve air circulation and to remove any fallen yellow leaves in the fall. I did this, which freaked out my father, who has no idea how plants work, but who liked the ground-dragging branches. I had cut off most branches to the trunk, and had left a few at about 4 ft high as stumps one foot out from the trunk, as I would need a saw rather than the clippers I had been using.

Once he saw what I had done I was forbidden to touch the tree. I told him it was possible leaves might return on the not-fully-removed branches, just as the oak he had topped off had sprouted new branches lower down. This year the tree has three times as many leaves and no blight and one of the three stub-branches has indeed leafed. So I want to lightly scar the bark of the other two, appl something waxy, and see what happens. I might be able to get my hands on auxin, but I was hoping there was something commercially formulated and easy to use not intended as a pesticide. I am not around all the time to maintain a will compress etc. (The other problem is the oly place I'd know to get willow cuttings would be on private land.) But at least I am encouraged by the above suggestions. μηδείς (talk) 21:08, 4 July 2014 (UTC)

July 5

Name that beetle

Beetle

Beetle

Can anybody ID this beetle. I found it in Cambridge Bay on Victoria Island (Canada) so it is obviously an Arctic dweller. It does not appear to be either Upis ceramboides or Cucujidae. While I forgot to measure it I would estimate that it was about 1 cm (0.39 in) long. Thanks. CBWeather, Talk, Seal meat for supper? 03:50, 5 July 2014 (UTC)

There are a lot of beetles out there. However, it does look like a Harpalus (genus), and several species are recorded from Northwest Territories as shown here. Mikenorton (talk) 09:45, 5 July 2014 (UTC)

I was thinking it looked like it could be a species of the genus Eleodes (unfortunately our coverage of this genus is poor, with a particular species at the genus article location, for some reason, but a common search engine image search will turn up many of the variants), but looking at Harpalus, it seems to share the rather distinctive morphology of the lower abdomen found in CB's specimen, so I think Mike is on the right track. Anisodactylus is another possibility. Certainly it seems to be a member of Carabidae/Harpalinae. Snow talk 10:10, 5 July 2014 (UTC)

Thanks. When I posted it I didn't realise just how many different types there were. CBWeather, Talk, Seal meat for supper? 18:39, 5 July 2014 (UTC)

If it's any consolation, very good pics, nice focus and detail! SemanticMantis (talk) 16:31, 6 July 2014 (UTC)

Thanks but I think that was more luck. First one I found in the house and was able to get it into a plastic tub. CBWeather, Talk, Seal meat for supper? 01:27, 7 July 2014 (UTC)

Keratometers

How accurate are keratometers in diagnosing astigmatism? Can it sometimes think someone with no astigmatism has astigmatism? For example, can dry eyes or even incorrect use of the machine cause this? 90.192.110.77 (talk) 11:44, 5 July 2014 (UTC)

See Keratometer, Astigmatism#Diagnosis, and Javal's Rule. The keratometer measures the physical dimensions of the cornea, so won't be affected by dryness. On the other hand, any sort of measuring equipment will give incorrect readings if it's used incorrectly. If you're worried about your eyesight, you should contact an optician. If you're worried about the competence of your optician, you should seek a second opinion. Tevildo (talk) 12:08, 5 July 2014 (UTC)

Scheiner disc?

Our article Keratometer (see previous question) refers to "Scheiner's rule" and a "Scheiner disc". Julius, or Cristoph, or some other scientist? There are several references to the device out there in optometric contexts, but something definitive about its history would be a useful addition to the appropriate article. Tevildo (talk) 12:13, 5 July 2014 (UTC)

This book gives two possible Scheiners in different chapters, either Christopher or Thomas, with the date given as 1619 in both cases. After checking with more sources, it seems that it was Christoph in his work Oculus, hoc est: fundamentum opticum, published in either 1619 or 1620, according to what shows up in this google book search. Mikenorton (talk) 12:44, 5 July 2014 (UTC)

And here's a quote (translated) from that work, describing the principle of the disc. Mikenorton (talk) 13:58, 5 July 2014 (UTC)

Thanks very much! This is Scheiner's original text, and this is a useful paper on the subject. Now, to Scheiner's Rule. I'm sure (a) it's the same Scheiner, and (b) tracking it down won't be too difficult. Tevildo (talk) 14:31, 5 July 2014 (UTC)

OK, "Scheiner's rule" is just "if you can see two images, your eye is out of focus." Now, where's the best place to put this? Should we have a new article on Scheiner disc, or should information on it go into another optometry article (Autorefractor, perhaps)? I don't think Christoph Scheiner itself is the _ideal_ location, but it's a possibility. Tevildo (talk) 10:33, 6 July 2014 (UTC)

Largest research centers in the world

What are the largest --employee-number-wise-- research hubs in the world? Thanks. --Schweinchen (talk) 12:30, 5 July 2014 (UTC)

Clarification of your question will help get better answers. Do you mean an organization, or a place, or both? It's an important clarification, because e.g. NASA and the CDC have many many researchers employed, but they are split across many different locations. Even large research universities often have several campuses, e.g. University of Texas and Ohio State University. Also keep in mind that a lot of scientists work at CERN, even though they have "home" institutions at some other place, and may not be technically considered employees. SemanticMantis (talk) 15:35, 5 July 2014 (UTC)

Many large research centres are part of military structures. You won't find very good public details about them. HiLo48 (talk) 22:30, 5 July 2014 (UTC)

I think that this answers my question. --Schweinchen (talk) 11:16, 6 July 2014 (UTC)

National Institute of Informatics is the largest? What is it/how big? (And I looked at our article.) 75.41.109.190 (talk) 13:14, 6 July 2014 (UTC)

No, not according to their "methods" page:

“ "Size (S). Number of pages recovered from four engines: Google, Yahoo, Live Search and Exalead. For each engine, results are log-normalised to 1 for the highest value." [5] ”

-- so your link is reporting that NII of Japan has the largest 'size' in terms of number of web pages-- that doesn't have much of anything to do with employment figures. SemanticMantis (talk) 16:30, 6 July 2014 (UTC)

Witches and stakes...

So in the UK, we are old that in "the olden days" witches were burnt at the stake. Has anyone ever found the body of a witch who was burned at the stake? --TammyMoet (talk) 17:57, 5 July 2014 (UTC)

Hmm. The physical remains of cremation don't really constitute a "body", so the answer to your question is probably "no". See Witch trials in the early modern period for our article. The last person to be burnt as a witch in the UK was Janet Horne in 1727. Tevildo (talk) 18:24, 5 July 2014 (UTC)

(ec) I remember hearing on QI (not always the most reliable source) that witches were more likely to be hanged than burned, and List of people executed for witchcraft seems to bear this out, as far as it goes. Burning was more commonly used to punish heresy, and for (non-noble) women convicted of treason (because the male sentence of being hanged, drawn and quartered would have been "unseemly" for women). As for finding the body of a specific victim, I have no idea. AndrewWTaylor (talk) 18:30, 5 July 2014 (UTC)

I refer you to Burning of women in England and Witch trials in the early modern period; the latter says "In England, witches were usually hanged before having their bodies burned and their ashes scattered. In Scotland, the witches were usually strangled at the stake before having their bodies burned — though there are several instances where they were burned alive". Alansplodge (talk) 20:02, 5 July 2014 (UTC)

The question doesn't necessarily ask whether witches were burned in the UK - it says "in the UK we are told that...". For a general account of witches burned at the stake see Death by burning#Witch hunts. Richerman (talk) 21:49, 5 July 2014 (UTC)

In British North America, in the Salem witch trials, those who were convicted (or pleaded guilty) were hanged. (One defendant who refused to plead was pressed to death.) Robert McClenon (talk) 22:04, 5 July 2014 (UTC)

Cremation may involve higher sustained temperatures than mere "burning" over a stack of wood. Is there evidence of any requirement that the fire at a witch burning be continued hot enough and long enough to reduce all bones and teeth to unrecognizable ashes? Isn't it likely that when the condemned was clearly dead they just buried or scattered the bones and teeth? Is there any historical report of the executioners building a new stack of wood, placing the remains on it, and continuing he process after the fire had burned down and perhaps the stake had burned and fallen over?? It would seem possible that someone might have collected and buried bones of some burned witch after the excitement was over and the crowd had gone home. Edison (talk) 02:16, 6 July 2014 (UTC)

Thanks for this thought Edison. I actually posted after reading that the Palestinian boy had been burned to death and they had discovered this after an autopsy, which implies that there was an intact body with internal organs. One thought led to another, and that's why I posted the OP. --TammyMoet (talk) 18:43, 6 July 2014 (UTC)

It's possible to do post-mortems on even cremated remains, though it takes an expert such as William R. Maples to do it. Even the tiny chunks of bone left over are enough for identification. Matt Deres (talk) 14:39, 7 July 2014 (UTC)

Why would we find bodies or bits of bodies? A simple Flame-Freezing Charm would render the flames harmless. Nyttend (talk) 22:47, 7 July 2014 (UTC)

Rocket launch sequence

In footage I've seen, they first start the rocket engines, then disconnect from the tower, then launch.

1) I wonder why the don't disconnect from the tower first.

2) If they aren't able to successfully disconnect, can they stop the engines, to abort the launch ?

3) Also, once they disconnect, I imagine that reconnecting would be difficult, but not impossible. Is this correct ?

StuRat (talk) 21:21, 5 July 2014 (UTC)

The answer to this question will depend on the type of rocket, but that sequence isn't correct for the Saturn V - on that spacecraft, the sequence was Start Engines > Launch > Disconnect Tower. The disconnection sequence was triggered by the movement of the rocket off the pad. This is just speculation, but I imagine that's to reduce the risk of a premature disconnection - if the disconnection signal was electrical rather than mechanical, it might be triggered accidentally. On the Saturn V (and even more so on the Space Shuttle, with solid-fuel motors), the main engines couldn't be (quickly) shut down once they'd started - in this case, the LES tower motor would be fired to remove the command module from the stack, and the Range Safety Officer would then initiate destruction of the rest of the vehicle. The Shuttle didn't have such an abort mode, which is why the Challenger disaster resulted in fatalities. The disconnection was done with guillotines, so it wouldn't be possible to reconnect (and I don't really see why you'd want to). Tevildo (talk) 22:06, 5 July 2014 (UTC)

If they disconnect first, then tried to start the engines, but there was a total ignition failure, then they might want to reconnect. StuRat (talk) 03:41, 6 July 2014 (UTC)

That's why they start the engines first, then disconnect. (The other reason is that when the rocket is at the launch pad, the tower actually supports its weight -- not the rocket's tail.) 24.5.122.13 (talk) 04:10, 6 July 2014 (UTC)

Actually, that's another good point. Disconnecting the tower before starting the engines would introduce the risk of (a) the rocket falling over before the engines start, due to high winds, etc, and (b) the rocket falling over when the engines start, especially if one engine were to start early. The risk of (b), in particular, is much higher and has much more serious consequences than flying the rocket with an arm still connected for the few seconds necessary to ensure a safe abort. Tevildo (talk) 10:48, 6 July 2014 (UTC)

Don't forget (c) the rocket falling over when the engines start, especially if one engine were late (or completely failed to start). Both b and c would result in dangerous thrust imbalance. - ¡Ouch! (^{hurt me} / _{more pain}) 08:19, 8 July 2014 (UTC)

I am willing to speculate that there is more than one connection to the tower. It would make sense to have two or even three steps to final disconnection. The first might be one that is connected manually when the vehicle is first brought into contact with the tower. It would be a robust system and could withstand fairly high winds. It would be disconnected manually, probably very early in the countdown sequence. There might be a secondary system that would be disconnected remotely but would be capable of being re-connected remotely if the launch were aborted. And finally there is the system that is disconnected remotely but cannot be re-connected. Such a cascade of connection systems would be consistent with the approach taken towards the engineering design of high-cost, high-risk, manned ventures. Dolphin (t) 05:54, 6 July 2014 (UTC)

For the Apollo program, the "robust system" was the Mobile Service Structure, which was removed the day before the launch. See this article. Tevildo (talk) 09:51, 6 July 2014 (UTC)

Mercury-Redstone 1#Causes of the failure sounds like the weight is supported by the rocket not the tower (and that at least the electrical connections are simple physical plug-in), and Mobile_Launcher_Platform clearly held the full Shuttle weight on the ends of the SRBs. DMacks (talk) 12:55, 8 July 2014 (UTC)

The weight of a launcher is not carried by the tower. Instead the launcher rests on a number of hard points around the skirt of the first stage, at the tail end. In most cases these are combined with a hold-down mechanism, which holds the launcher in place and stabilises it against sideways motion from wind. Crucially, these hold-downs remain while the (liquid-fuelled) motors are spinning up, and are only released when all the motors are running correctly; typically liquid engines are ignited a few seconds before T-0, and the release of the hold-downs marks the actual launch. This time window means it's possible to notice that the motors aren't running properly and shut them down, without the launcher starting to lift off the pad. A 2012 Falcon-9 launch aborted less than a second before launch, when automated systems detected one motor was out-of-spec and, rather than release the hold-downs, it killed the motors.[6] Hold-downs come in two forms. The first is a system of clamps, which grab onto tabs on the rocket, and pull back to cut it loose. Pictures of the Saturn V hold downs (and the massive steel arms that held up the laden rocket) are here. Space-X uses a similar system. The second option is a fixed nut-and-bolt, where the hard points are bolted to the launch platform - releasing this hold-down scheme involves explosively severing the bolts or nuts. The Space Shuttle used the latter system, as discussed here, with four hold-down points on each SRB and frangible nuts. On the pad, the entirity of the STS system was carried by these 8 points - there was no hold-down on the orbiter or the external tank. The designers of the Space Launch System are concerned that these won't be sufficient to stabilise their rocket, and they're considering adding a vehicle stabilizer arm, which would allow the tower to prevent the launcher from swaying prior to launch; this would disengage at T-0. A notable exception to this is the Soyuz launcher; the Soyuz doesn't have hold-downs and is serviced by a pair of boom arms (not really a tower) which retract just before launch. Instead of resting on its tail, the Soyuz hangs suspended over the pit on four angled gantries which fit around its midsection (it's a bit like holding your head up by putting your palms under your chin and your elbows on the desk). When the Soyuz launches these arms fold back - they're counterweighted so they move out of the way when they're not holding the launcher's weight. -- Finlay McWalterᚠTalk 13:40, 8 July 2014 (UTC)

July 6

Household LED lighting

Some LED lights for household use to replace incandescents have a similar frosted, globular appearance, and a similar size, to the bulbs they are replacing. An LED drawing about 12 watts is intended to replace an incandandescent 60-watt light bulb or thereabouts. My question is, how many individual light-emitting diodes are inside that LED "bulb"? Or more generally, what are the specifications of the largest single LEDs now in common use? --98.158.139.69 (talk) 07:54, 6 July 2014 (UTC)

There are a large number of incandescent replacements of various quality and using a large variety of LEDs types and brands so I don't know if your first question can meaningfully be answered.

As for the second, do you really mean largest? Or brightest?

One of the brightest single die LED is the latest version of Cree XM-L [7]. However although it can be powerful enough to beat a 60W incandescent, it isn't really intended for the purpose you describe and isn't used much for it. (Note that despite the similar name, the XM-L Easywhite isn't that similar as it's a multidie LED.) See e.g. Cree's own incandescent replacements which definitely don't use an XM-L or even a single LED of any type [8] by any resonable definition.

Then there's stuff like the SST-90/CST-90 etc which are single die and can be brighter than the XM-L although with a much larger surface area [9] [10] [11]. But again, although it can be brighter than a 100W incandescent, isn't really intended or well suited for incandescent replacements and so isn't used much for that purpose.

Of course you can also get massive LED arrays. E.g. BridgeLux make one that can output up to 16k lumens [12] [13] (probably some more details [14] on the test) [15] which is a lot more than any 60W incandescent (probably closer to a 750W halogen). I mean at that level, the LED itself is likely consuming well over 100W. (If you're really interested in size, the Vero 29 LED array is I believe ~29mm in diameter hence the name.)

I doubt this is the most powerful (or largest), many manufacturers have their own arrays, particularly the so called "chip-on-board" [16]. And depending on the quantity required, they may be able to produce something more if really needed.

Chinese manufacturers in particular seem quite willing to do that, even for relatively small quantities, although I'm not sure that the output will necessarily be much better than from a reputable manufacturer, or that it will last long or that it will be very uniform. But see e.g. these "500W" LED www.aliexpress.com/item/500W-Lamp-LED-chip-LED-chip-size-Taiwan-Epistar-45x45mil-47000-5000LM-FREE-SHIPPING/1401410645.html www.aliexpress.com/item/Free-shipping-500w-led-chip-white-color-8-4A-72-82V-3-years-warranty-high-brightness/1421216136.html www.aliexpress.com/item/500W-Cool-Cold-White-6000K-10000K-14000K-20000K-High-Power-LED-Light-45Mil-Chip/1253392737.html (which are ~ 47.6x47.6mm). Closest video I could find is this 200W [17] (running at 170W) but I don't know whether it's a Chinese LED and at 200W it probably isn't that different from the Bridgelux Vero 29 anyway.

In other words, the answer to your second question depends a lot on stuff like, what do you mean by "single LED", "common use", "largest"/"brightest".

If you're imagining use in household lighting, one of the obvious complicating factors is it's not necessarily meaningful to simply think of these in isolation. As shown by the incandescent replacement cases, using a single LED may actually be far more difficult given the specific light pattern requirement. Also it tends to complicate heat management. Of course using too many LEDs may similarly make it complicated to achieve your desired light pattern and otherwise complicate design. On the other hand, as particularly obvious in the flashlight arena, having a bright single LED (whether multiedie or single die) may sometimes be less important than having a surface brightness (i.e. the light output is spread out over a small area), one of the reasons why stuff like the SST-90 is much less popular than the XM-L. (The other is efficiency which of course related to both battery life and heat output and is particularly important in a flashlight.)

Besides all that, I don't believe most household lighting is really that well designed. For starters, until very recently the sort of lights available were very limiting, even more so if you only wanted incandescents or halogens. This and other factors means many people have a small number of bright lights which doesn't give that uniform lighting, when they'd probably be better served by more smaller lights. In other words, what's commonly used for incandescent replacements (or other replacements) may not necessarily be what would be well suited and commonly used if you can actually afford a professional lighting designer.

Nil Einne (talk) 16:42, 6 July 2014 (UTC)

Thanks for that! You asked "what do I mean by single LED". I have here at hand a flashlight that uses 4.5 volts and has a clearly visible array of 16 LEDs. When I look at LED turn signals on cars (presumably using 12 volts) or LED traffic lights (presumably using 120 volts or more), each light similarly displays an array of LEDs, but those LEDs are obviously larger than the ones in the flashlight. So I was presuming that the LED "light bulb" I talked about would contain a similar array of LEDs, using 120 volts, and I wondered how many were likely to be in there. (Yes, I realize that the voltage to the individual LEDs may be lower if they are wired in groups in series; I just mention the voltage incidentally.) Your second link refers to 80 LEDs in a "bulb" of similar style and size, so that's an answer.

As to the second question, I didn't have any specific interpretation in mind, but yours (or something less detailed) is the sort of answer I was expecting. Thanks again. --50.100.189.160 (talk) 05:38, 7 July 2014 (UTC)

You said "incindentally", but it's worth pointing out that LEDs must run at specific (low) voltages which correspond to the photon energy (and thus vary by color). --Tardis (talk) 06:11, 7 July 2014 (UTC)

People who are immune to addiction

For understanding any biological process it is invaluable to look for mutants that fail to undergo it. It would seem like the same should be true for addiction. Simply doing an online search, I see people who claim to be able to stop smoking cigarettes whenever they wish ( [18] [19]). But I'm having trouble finding the inspiration to think of a way of phrasing the search to pull out serious research papers, indeed if any exist. Has anyone tried to find these people and look for a genetic basis? Wnt (talk) 18:03, 6 July 2014 (UTC)

There is some evidence that people who are genetically predisposed to very low levels of novelty seeking (such as myself) also have a low (but not zero) risk of developing addictions, but the evidence is not conclusive. 24.5.122.13 (talk) 22:12, 6 July 2014 (UTC)

Identifying a unique group of people who are (intrinsically rather than situationally) immune to (substance or behavioural) addiction in order to probe what genetic mutation might be responsible for their immunity is a research idea that runs into ethical and practical challenges. Genome-wide association study (GWAS) is in its infancy and needs a massive number of statistical tests to eliminate false-positive results. One problem is that genes identified in GWAS for drug dependence may be involved either in adjusting brain wiring prior to drug experiences, subsequent to them, or both. On-going research into drug, alcohol and tobacco addiction focusses on Dopaminergic pathways of which the Mesolimbic pathway is believed to be a "reward" pathway. The Substance dependence article gives over 100 references in this field. 84.209.89.214 (talk) 00:05, 7 July 2014 (UTC)

You're absolutely right about the difficulty of GWAS even for far more easily diagnosed disease. I was hoping for some sort of gift from the gods here - an old history that carefully analyzed the opium addiction of hundreds of Chinese nobles in a few pedigrees who are now preserved safely in a crypt, or a lucky hit from the reverse genetics of a particular allele of something like dopa decarboxylase. I suppose one of the countries like the UK that DNA test all arrestees might conceivably cross-reference that with blood data on addictive drugs and then see which required treatment for or showed some visible sign of withdrawal, but as you say that is an ethical line I'm not at all eager to see crossed. Wnt (talk) 14:28, 7 July 2014 (UTC)

There are certainly people who aren't prone to specific addictions, but not being prone to any addictions would be quite rare, if it exists at all. You might have better luck looking at meds which cause a wide range of addictions as a side effect. See Dopamine receptor agonist#Side-effects for an example. If we can figure out what it's doing, that should help us to develop meds which do the opposite. StuRat (talk) 04:09, 7 July 2014 (UTC)

This is a good lead. Searching d3 agonist addiction pulls out some less than compelling information about buspirone being used to prevent reinstatement in rats,^[20] slightly better evidence for effectiveness of an ingredient in Chinese herbal medicine (levo-tetrahydropalmatine),^[21] and various other mysterious effects.^[22][23] But I find these studies frustrating - you're seldom sure what protein is really being targeted, the authors end up trying to explain why certain doses have a small effect and larger doses have none. Numbers are small, error bars overlap, etc. No doubt there is something to it but I can't shake the impression that they're looking at something like the correlation between whacking a mouse with a rolled-up newspaper and how long it takes to solve a maze afterwards. Wnt (talk) 14:59, 7 July 2014 (UTC)

It's not even clear that the current use of the term "addiction" lends itself to such distinctions. During the period when cigarette smoking was still being studied as being carcinogenic, there was a distinction between habit-forming and physiological addictions. Cigarette smoking fell into the habit-forming arena whereas opiates were physiological. Heroin metabolism changes liver function, for example, and could cause death if withdrawn. Nicotine did not. To elevate the dangers of cigarette smoking, there was a campaign to change the definition of addiction. It's current form is something along the lines of "any voluntary behavior that a person chooses to do despite negative social or physical impacts" (paraphrased). So alcohol drinking that doesn't damage social relationships or health would not be considered "addiction" but smoking would if it continues despite the person knowing the risk of lung disease (this redefinition was the objective sought to combat smoking and elevate treatment options). A person with end stage cancer that is on Fentanyl and would suffer severe withdrawal symptoms and possibly death if Fentanyl were withdrawn is not considered "addicted" though they would be classified as "physically dependent." Since the definition is so entwined with political correctness and human behavior, it would be difficult to create an ethical and scientifically meaningful experiment. Gambling, sex, heroin, methamphetamine and tobacco are all potentially clinical addictions with very different mechanisms on behavior. A confounding question like "can someone be addicted to second-hand smoke?" or "why is the cancer patient using 200mg of Oxy a day not addicted, but the 40mg recreational user an addict?" These are political-social constructs of the definition and not a scientific distinction. --DHeyward (talk) 10:29, 7 July 2014 (UTC)

And knowing that behavior is ultimately driven by brain chemistry means that all addiction could be described as physical addiction, such as to the dopamine released by engaging in that behavior. Therefore, the distinction of whether they will suffer measurable physical harm if they go "cold turkey" seems like a more meaningful one, to me. StuRat (talk) 14:49, 8 July 2014 (UTC)

Geomagnetism

How are the earth's internal currents (that cause its magnetic field) generated? Is there a big battery in there?--109.149.211.41 (talk) 18:27, 6 July 2014 (UTC)

Take a look through Earth's_magnetic_field#Physical_origin and see if it answers your question sufficiently. Mikenorton (talk) 18:32, 6 July 2014 (UTC)

The key is dynamo theory. I believe that I have seen a diagram of a cleverly constructed mechanical dynamo, containing no magnets but only a conductive disk and electromagnets powered by the disk, which I was told would produce electricity and a magnetic field when spun above some velocity. But I haven't seen it in quite some time. Wnt (talk) 18:35, 6 July 2014 (UTC)

Not a battery but a giant magnet in pictorial terms. The Earthcore is believed to be composed primarily of iron aka ferromagnetic material. --Kharon (talk) 22:44, 7 July 2014 (UTC)

Hehe, you're barking up the wrong tree. So far as I know (and I'm no expert either) the Earth's core is vastly hotter than the 1000K Curie temperature of iron, i.e. it's not ferromagnetic. It's a conductor, moving, that has electric currents because it is moving through its own magnetic field, and maintains a magnetic field due to its own electric currents... it is, in short, as fearsome a knot of diffy-q's as you would ever cross paths with. Wnt (talk) 00:29, 8 July 2014 (UTC)

If you think the Earth's magnetic field is complicated, look at stellar magnetic field. StuRat (talk) 14:52, 8 July 2014 (UTC)

July 7

Bird identification

This weekend I was camping in Upstate New York and I saw some birds that I'd like to know more about. I was camping in a hay field and in the mornings there were several birds that were pecking around the field. They weren't there the rest of the day, just the mornings. When I was playing fetch with my dog, and I threw the ball near the birds, the nearest one to my dog would fly near my dog as if trying to scare her away. So, they seem to be at least a little territorial and once I saw that, I stopped throwing it anywhere near the birds.

As far as their appearance goes, they were white and either brown or grey. I didn't want to get very close, so I couldn't be sure about the color. They reminded me a bit of sandpipers in the way they walked. Their beaks were at least an inch long, possibly two. The beak wasn't really long and thin but more triangular. Their backs were brown or grey. The bellies were white. Across the chest coming up from the belly was a horizontal band of the color, then a band of white, and then the neck was colored. And they were larger than sparrows or such but weren't as big as crows.

Any help? Dismas|^(talk) 01:49, 7 July 2014 (UTC)

List of birds of New York may help. --Jayron32 02:01, 7 July 2014 (UTC)

Going through that list, does killdeer work? --Jayron32 02:09, 7 July 2014 (UTC)

Nearly. This image seems to match the color/white/color banding I saw on the chest. Dismas|^(talk) 03:18, 7 July 2014 (UTC)

Note that killdeer are known for diving at animals and people they consider to be a threat, only to veer away at the last moment, in order to drive them away. So, I think that's a match. StuRat (talk) 03:54, 7 July 2014 (UTC)

Thank you, both! Dismas|^(talk) 23:17, 7 July 2014 (UTC)

Dried milk

With the dishwasher temporarily not working, my roommate and I are currently handwashing everything, and sometimes (like now [hangs head]) the dishes pile up for a few days. Of all the dirty dishes that we normally produce, the most difficult to clean are the glasses in which a tiny amount of milk was left to dry out, rather than rinsing it out and leaving a little water behind. Part of this is due to the physical location (it's at the bottom of the glass), but even so, it's far harder to scrape out the dried milk than anything else, as it adheres to the glass with an unusual firmness. Can anyone imagine why? I'm running water into the cup and then using a soap-fortified scouring pad that looks remarkably like this image, if that helps. Nyttend (talk) 02:53, 7 July 2014 (UTC)

When I was very much younger casein glue made from milk was a very effective way to stick things together. That link actually mentions that it is still used in the labelling of bottles, so presumably it works well with glass. Your kitchen may have become a glue factory. HiLo48 (talk) 03:26, 7 July 2014 (UTC)

I don't think it's just milk. Any number of substances that rinse right out with water when wet seem to become well adhered to the cookware once they dry. Consequently, rinsing the dishes immediately saves a heck of a lot of effort later. Also, dishes which lack sharp corners make it easier to wash up. StuRat (talk) 03:49, 7 July 2014 (UTC)

Somewhat OT and I'm not certain this will help in your case but generally speaking if let something which has dried up soak for a while (probably at least 30 minutes) it will be a lot easier to clean up. Re: what StuRat mention, it may not be quite as easy if you hadn't let it dry up, but it's easier than trying to clean it after only a minute or two of soaking. In fact particularly with pots and pans just used for cooking, it may sometimes be easier to clean up after soaking than it is straight away. As for the more general case, beyond just cleaning it up straight away, or at least rinsing out the item, you can always fill it with sufficient water that it's not going to dry up. Nil Einne (talk) 06:13, 7 July 2014 (UTC)

That's my usual approach too. ←Baseball Bugs ^{What's up, Doc?} carrots→ 09:22, 7 July 2014 (UTC)

Being rather on the slob side of life, I've found that using very hot water, plenty of soap, and the rough side of a sponge works exceptionally well (even without soaking) - then again, the hot water at my house is very very hot. The simple solution, though, is to rinse out oatmeal, milk, and other things like it ahead of time.Phoenixia1177 (talk) 04:14, 8 July 2014 (UTC)

Is it worth pointing out that the OP actually asked "Why?" HiLo48 (talk) 04:34, 8 July 2014 (UTC)

As in, why does the residue of a liquid cling to the container after the water has evaporated? ←Baseball Bugs ^{What's up, Doc?} carrots→ 15:43, 8 July 2014 (UTC)

I'm not sure if that was addressed to me or the discussion thus far, but it's the same reason that any drying adhesive works. Also relevant: the history section of the Adhesive article mentions casein, Casein Glue, and [24].Phoenixia1177 (talk) 18:57, 8 July 2014 (UTC)

In the case of a liquid in the container that includes anything "sticky" (eg, casein, sugar, gelatine), the sticky component becomes more concentrated as water evaporates. This would be part of the reason why. CBHA (talk) 19:02, 8 July 2014 (UTC)

Level of humidity and comfort/discomfort on the human body

Is there a chart somewhere (on Wikipedia or elsewhere) that breaks down the categories of humidity and the relative comfort to humans? I am referring to the humidity level only. I am not referring to a chart that displays humidity levels alongside actual temperatures (such as the charts located at the article for Heat index). I have looked in Wikipedia and in Google searches and can't seem to find anything. Sometimes, on my local news, the weather report of the meteorologist will include a chart that says something like this: Humidity 50 to 59% = Comfortable; 60 to 69% = Mildly Uncomfortable; 70 to 79% = Extremely Uncomfortable; 80 to 89% = Dangerous. (I just made up those numbers, but the chart would look something like that.) Does anyone know where I can find a chart like this? Thanks. Joseph A. Spadaro (talk) 17:42, 7 July 2014 (UTC)

Any such chart would be very subjective. Some people enjoy high humidity. Some hate it. Some adapt to it, or its absence, over time. And temperature is always relevant to comfort too. HiLo48 (talk) 17:46, 7 July 2014 (UTC)

Relative humidity is very closely tied to air temperature, so you can't have a useful chart without knowing the temperature it was made for. The dew point is a measure of absolute humidity, so it is not related to the air temperature. There is a chart in our dew point article relating the dew point to human comfort. Katie R (talk) 17:54, 7 July 2014 (UTC)

I would speculate your local news was taking a slice through the heat index chart you linked to for the temperature it was expected to be that day. Our heat index chart doesn't break down "mildly uncomfortable" (for 80 degrees all temperatures are in yellow), but I'm sure there are some opinions about that out there. Or, being entertainers, the weather forecasters might just draw the lines ad hoc based on their own preferences. Wnt (talk) 18:47, 7 July 2014 (UTC)

Thanks. Your response confused me. Regarding my local weather report: Why would he do as you suggested? The weather reporter would know the specific local temperature (as you stated), but he would also know the specific local relative humidity as well ... correct? If he knows both values, why would he bother to create that speculative/hypothetical generic chart for other values (that he knows do not even exist today)? That would be akin to him saying something like this: "Today's temperature is 80 degrees F. And today's relative humidity is 52%. Therefore, it will be a relatively comfortable day today. However, if today's relatively humidity was 84% (which it is not), then today would have been very uncomfortable for us" (or something to that effect). Why would he offer hypothetical information like that (via his generic chart), when he knows the exact specific information to offer for the day? Or am I misunderstanding your post? Thanks. Joseph A. Spadaro (talk) 19:33, 7 July 2014 (UTC)

He might have been trying to "educate people about what humidity is". I don't know. It's a TV show for entertainment, there's some creativity involved, and I can't really say what his motivation is. Wnt (talk) 11:32, 8 July 2014 (UTC)

So, if a person knows one statistic (relative humidity) without knowing the other statistic (temperature), there is no general categorization of comfort level? If I saw somewhere that the relative humidity was, say, 75%, that wouldn't tell me anything at all (with regard to comfort level), until and unless I also knew the actual temperature? Is that how this works? Thanks. Joseph A. Spadaro (talk) 19:21, 7 July 2014 (UTC)

Yes, you need both. For me, e.g., 75% humidity at 40F would be chilly, while 75% humidity at 70F would be comfortable, and 75% humidity at 104F would be uncomfortably warm. SemanticMantis (talk) 19:34, 7 July 2014 (UTC)

(edit conflict) Correct. A psychrometric chart can be used to get an idea of the relationship between all the various measures of temperature and humidity, but it can be tough to understand at first. With an air temperature (dry-bulb) of 25 C and 75% RH the chart gives a humidity ratio (measure of absolute humidity) of .015, which a psychometric calculator [25] shows is equivalent to a dewpoint of about 20 C, which out dew point article claims is somewhat uncomfortable for most people. However, with an air temp around 17 or 18 C the ratio is .01 or 14 C dew point, which falls in the comfortable range. Katie R (talk) 19:35, 7 July 2014 (UTC)

Also, notice that the calculator isn't needed - the wet-bulb temperature at 100% RH is the same as the dew point, so that figure can be read right off the chart. It slipped my mind when I first wrote the response. Katie R (talk) 19:42, 7 July 2014 (UTC)

89% here and I'm "mildly uncomfortable" after digging a 3x4x3 foot hole. Three on the UV index. The moon is waxing gibbous. Guess my temperature within three degrees (Celsius) and win a signed copy of "Burnin' Up" by Judas Priest (the only one without a Wiki article). InedibleHulk (talk) 19:54, July 7, 2014 (UTC)

@InedibleHulk:, 25 °C (77 °F). CBWeather, Talk, Seal meat for supper? 01:17, 8 July 2014 (UTC)

Aw, so close! It was 21. Dealer wins. But nobody goes home empty-handed: Here's the never-overplayed "Living After Midnight". InedibleHulk (talk) 01:25, July 8, 2014 (UTC)

Both temperature and wind speed figure into it. As an example, 20 below with low humidity and calm winds can be a lot easier to take than 20 above with high humidity and strong winds. ←Baseball Bugs ^{What's up, Doc?} carrots→ 19:36, 7 July 2014 (UTC)

Thanks. So this is the part I am not understanding. I look at my local weather report (or I watch it on the TV news). The weather guy tells me what today's temperature is. The weather guy also tells me what today's relative humidity is. After knowing these two values, I then have to go "dig up" that heat index chart to make sense of what this all means? I can't imagine that the TV weather reporter works on the premise that after he offers his data, his viewers go dig up that heat index chart to make sense of it all. No? Joseph A. Spadaro (talk) 19:43, 7 July 2014 (UTC)

Local weathercasters that I'm familiar with will usually give the heat index as well, especially on a very warm day. As in, "It's 87 but it feels like it's 93." ←Baseball Bugs ^{What's up, Doc?} carrots→ 20:19, 7 July 2014 (UTC)

Is it more likely that the local weather reporter was offering a chart/graphic based on the chart located at the dew point article under the section titled "Relationship to human comfort" (using the second and third columns of that chart)? Maybe the weather reporter was discussing (on his chart) humidity as measured by dew point (in degrees) rather than humidity as measured by relative humidity (in percent). Does that seem more likely? Joseph A. Spadaro (talk) 19:50, 7 July 2014 (UTC)

Yes. I agree with Katie that dew point is a much more useful measure of humidity. I use this site to get the dew point forecast, since my local weather station is similarly useless: [26] (I normally only select the temperature and dew point check boxes). Specifically, I need to know whether to leave my windows open with fans in them at night or not. With a dew point over 70F, forget it, the humidity isn't worth it, I run the A/C all night instead. With a dew point under 60F, it is worth using the fans. Between 60 and 70F, it depends on how hot and humid it is inside.

Now, as to how relative humidity got to be what is reported on weather forecasts, that's a mystery to me. It's just nowhere near as useful as the dew point. Weathermen do provide all sorts of extraneous info, seemingly designed to prove how smart they are, that has nothing to do with how to plan your day. Telling you what it would feel like if we changed the temperature or humidity by a given amount is just one example. StuRat (talk) 20:01, 7 July 2014 (UTC)

As I understand it, the dew point is about as low as the temperature is going to get until the next air mass moves in. Hence it can feel muggy at 70. In the frozen north, as you may have noticed, when the humidity is reasonable you have to scrape the frost off your car in the morning. When it gets to 20 below, there may be no frost to be scraped off. ←Baseball Bugs ^{What's up, Doc?} carrots→ 20:22, 7 July 2014 (UTC)

(ec) Not everything a meteorologist discusses is made for telling people what kind of shirt to wear today, though. A landscaper might awake in the morning and look at the RH, for example; near 100% indicates that there's probably quite a bit of dew on the grass, and he should wait before firing up the lawnmower. He could arrive at a similar conclusion by looking at the current DP and temperature, but that's true of many indices a meteorologist provides. In general the DP is much more useful than RH, but I wouldn't assume your local weatherman shows both to boost self-satisfaction... it's just standard as part of any weather broadcast. – Juliancolton | ^Talk 20:25, 7 July 2014 (UTC)

Here the local TV stations rarely tell us the dew point, but tell us the relative humidity religiously, as if it was somehow important. StuRat (talk) 20:59, 7 July 2014 (UTC)

It is religiously important. Humidity's our proverbial scapegoat. If we blamed the sun directly, we'd anger Him. And nobody wants an Angry Sun. InedibleHulk (talk) 21:04, July 7, 2014 (UTC)

ZrZn₂

What do we call this compound? It exists, since apparently it's been reported as a possible ferromagnetic superconductor, but that's all I know. I didn't realise that it was possible for such metal-on-metal compounds to exist, and the naming isn't mentioned in IUPAC nomenclature of inorganic chemistry. Nyttend (talk) 23:53, 7 July 2014 (UTC)

Is it not a ceramic, in the same fashion as other metal/semimetal compounds from comparable chemical groups, like hafnium diboride, titanium dioxide, and zirconium diboride? ... or is it an alloy with more metallic-like characteristics? It seems to be a unique material that's somewhere in-between. There are a wide variety of research papers [27] [28] [29] that seem to indicate a diffusive equilibrium of zinc-zirconium, with many possible stoichiometric ratios coexisting. That sounds like an alloy almost by definition.

This paper - The Zn-Zr System (Dutkiewicz 1992) appears to be the grandfather-paper that's commonly cited among all the others. It may be the authoritative reference. Nimur (talk) 01:34, 8 July 2014 (UTC)

The typical term for such a compound is an intermetallic. Mr.Z-man 03:19, 8 July 2014 (UTC)

I'm sorry: I meant "what do we call this specific compound", like how we call NaCl "sodium chloride", not simply "a salt". Nyttend (talk) 04:46, 8 July 2014 (UTC)

Zirconium dizincide - there are other dizincides, as shown here (I've found reference to calcium, copper, magnesium, platinum and sodium versions). Mikenorton (talk) 07:11, 8 July 2014 (UTC)

Or just zirconium zincide, as in this US patent (assuming that's not ZrZn). Mikenorton (talk) 19:59, 8 July 2014 (UTC)

July 8

Simple change to laws of Physics to reverse cup anemometer

Is there some simple change to the laws or constants of Physics, that will cause cup anemometers to rotate in the reverse direction?

That is, I want clockwise-rotating anemometers to rotate anticlockwise, and vice versa.

Thanks in advance --RM — Preceding unsigned comment added by 121.247.86.28 (talk) 12:10, 8 July 2014 (UTC)

Probably not without changing the universe in dramatic ways. StuRat (talk) 14:07, 8 July 2014 (UTC)

Turn the anemometer upsidedown? CBHA (talk) 14:53, 8 July 2014 (UTC)

Or the OP could stand on his head while observing it. ←Baseball Bugs ^{What's up, Doc?} carrots→ 15:40, 8 July 2014 (UTC)

We're discussing changing the universe so presumably the solution would be to turn the universe upside-down, not the anemometer. F=-ma would be interesting but I have a feeling the rest of the universe wouldn't work well enough for your anemometer and wind to continue existing. Katie R (talk) 16:35, 8 July 2014 (UTC)

The most obvious solution is to turn the time vector 180 degrees. To accomplish that, the OP would need to leave a message in God's suggestion box. ←Baseball Bugs ^{What's up, Doc?} carrots→ 17:11, 8 July 2014 (UTC)

In the mean time, just put the battery in your analog clock in backwards. Bonus, your sense of "clockwise" also reverses, so the anemometer now is already going backwards in that sense. DMacks (talk) 17:22, 8 July 2014 (UTC)

What we would need to do is arrange things so that the drag coefficient of a concave hemisphere is greater than that of a convex hemisphere. Without attempting to think about the maths, possibly if air were rheopectic, so that the slower air associated with the concave vane would have a lower viscocity than the faster air at the convex vane, and therefore generate less of a drag force? Tevildo (talk) 20:30, 8 July 2014 (UTC)

Thanks Tevildo.

I read up about drag. Pressure drag is the strongest component of drag here, am I right? Assuming that the other components of drag are negligible, is there a simple explanation as to why pressure drag of a concave hemisphere is less than that of a convex hemisphere? And what are the laws/constants that can be altered to invert this? --RM

From what I infer from Anemometer, the actual wind speed is calculated from a combination of the "captured" air in the cups and the partially offsetting drag the wind hitting the back of the cups. That calculation is going to vary depending on the shape of the cups, and the article mentions an optimal construction of the cups. I'm at a loss to comprehend what laws of physics would have to change to make the flow of gasses and liquids behave differently than they do. ←Baseball Bugs ^{What's up, Doc?} carrots→ 22:45, 8 July 2014 (UTC)

The answer to 'what are the laws/constants that can be altered to invert this?' is 'None.'

I'm not just being flippant. Not only are the laws of the universe fixed, they're also a matched set. All the laws we see in action are the product of the comsic and quantum scale laws that we have come to regard as fundamental. The behaviour of a human-scale device like an anemometer depends on the laws for the fundamental particles, in ways that are difficult to comprehend. AlexTiefling (talk) 22:55, 8 July 2014 (UTC)

Astigmatism

Are small astigmatisms of -0.25 or less normally corrected? 82.132.216.31 (talk) 13:48, 8 July 2014 (UTC)

With glasses, it's easy to correct astigmatism, so they might as well. However, since contact lenses are normally free to rotate, it's more of a challenge to correct for astigmatism there. StuRat (talk) 14:04, 8 July 2014 (UTC)

My personal experience is that optometrists only measure and specify prescriptions (for e.g. astigmatism, myopia) in multiplies of 0.25 dioptre, but this might be outdated. Without the need for other associated correction (e.g. myopia), most people would not bother with glasses for such limited astigmatism. If glasses are being prescribed anyway, 0.25 dioptre might be corrected, but not say half of that. With contact lenses, I would expect this not to be corrected – basically exactly what StuRat is saying. —Quondum 18:56, 8 July 2014 (UTC)

I have 0.50/0.75 astigmatism correction on my contact lenses. AFAIK it's not a big deal to fix it in contacts, it's just an engineering problem that has been solved. 88.112.50.121 (talk) 19:08, 8 July 2014 (UTC)

My wife was astigmatic and wore contacts (before she had her eyes lasered!) - and the weighted/rotating contact lenses were a continual pain. The problem is that they get rotated out of position for one reason or another and actually make your vision worse until they move back to the correct position. She'd find that blinking kinda helped - but the ones that rely on gravity to do the job suck when you're driving because every time you take a corner, centrifugal force messes up their position. So I strongly disagree that it's "been solved" - the "solution" is only partially effective. SteveBaker (talk) 20:09, 8 July 2014 (UTC)

AFAIK the gravity-driven solution is old fashioned, first generation kind of stuff. It's now driven by micro serrations on the lens, and as the wearer blinks, the eyelid vs. serration action will orient the lens, gravity has nothing to do with it. Works fine for me, sorry it didn't work for your wife. 88.112.50.121 (talk) 20:32, 8 July 2014 (UTC)

SLEEP STUDY

Can anyone help me find out when (what year) the United States Air Force conducted it's first sleep study for Sleep Apnea? Thank You! B~u~g~g~e~d — Preceding unsigned comment added by 173.171.120.204 (talk) 21:01, 8 July 2014 (UTC)

Biological taxonomy (history of)

Which taxa have not been revised since Carolus Linnaeus introduced his system of biological taxonomy?
—Wavelength (talk) 23:52, 8 July 2014 (UTC)