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August 4

Why males in animal species are considered the default variant instead of females?

Sorry, I don't know where This belongs. It seems male is sometimes seen as the default gender, such as in language (for example, the words actor and steward usually refer to males). Pictures I've seen of lions, deer, and mallards are mostly of adult male ones. Adult male lions have manes, adult male deer have antlers, and adult male mallards have green heads. However, it is only the adult males of these species which have these characteristics. Juveniles, whether male or female, of these species look like their mothers (juvenile lions are maneless like their mothers, juvenile deer lack antlers like their mothers, juvenile mallards are brown like their mothers. So how come the males of animal species are the ones which are usually considered the default variant, even though the females are the ones which have the typical look? Yellow Sunstreaker (talk) 01:38, 4 August 2017 (UTC)

I think it's because the males usually look more conspicuous/more distinctive, as opposed to the females which are more generic-looking -- see Sexual dimorphism. 2601:646:8E01:7E0B:9149:D64B:8DA2:C52C (talk) 02:19, 4 August 2017 (UTC)

Agreed. In many cases the species can't as easily be identified by the females. Which of these can you most quickly identify as a mallard ? [1] StuRat (talk) 03:06, 4 August 2017 (UTC)

Yellow Sunstreaker: The same applies to humans too. Often, a stick figure of a human implies male. That is the default sex. A little triangle resembling a skirt implies female. In biology at the cellular level, the ovum is fertilized by male or female sperm. In language, male is the default gender. Female is the exceptional gender. 50.4.236.254 (talk) 02:36, 4 August 2017 (UTC)

"female sperm" -- What are you talking about? Please give references when responding to queries at the reference desk. SemanticMantis (talk) 03:35, 4 August 2017 (UTC)

Hmmm... I think I used the incorrect terminology. I meant to refer to different sperm cells in the adult male. Some sperm can make a female child, and some can make a male child. See sexual differentiation in humans. 50.4.236.254 (talk) 04:07, 4 August 2017 (UTC)

This is not an animal feature, it's a feature of human language, human sexism, and human ontology. See our nice article at male as norm. See other popular coverage here [2] [3] [4]. SemanticMantis (talk) 03:35, 4 August 2017 (UTC)

It's a feature of human language to assign a grammatical gender to species (or even things, even when the language has a neutral), but it's not always male (I am not even sure male is more frequent than female) and there are much variation depending on the language. English assign a female gender to ships (despite the fact that neutral exist), god knows why, and for sure Englishmen do not scorn ships, do they?

male as norm is just "A feminist" POV (not even "all feminists"), as evidence by its very first word "In feminist theory, etc.".

I know of a fierce feminist that feels pissed off (and let you know in dire words) if you dare use a specific female form when her sex is just out of scope -- that is, in pretty much every life situation, noticeably at workplace. In her POV, male is not the norm, it is neutral, sexless, applying to just everyone (that is, it is nothing, while female IS special); only when you want to specifically refer to someone sex, you have to use special language feature, female form for women, other sort of manhood trait for male (for lack of specific genre for them in language)

Gem fr (talk) 10:38, 4 August 2017 (UTC)

• In species where the female is more interesting, she'll normally be the default type (the default bee is the worker, not the drone; the default anglerfish is the female with the fishing lure, not the male who is basically just a floating genital), and the same is true of domesticated species where the females are bred for their eggs/milk (see chickens and cattle/cows) or where males are relatively rare (ask someone to draw a sheep and they'll probably draw a ewe, not a ram, since farmers don't keep many rams to prevent fights). Smurrayinchester 09:07, 4 August 2017 (UTC)

In pop-culture, this often gets subverted. Cartoon worker ants or worker bees will almost invariably be portrayed as male. (Antz,Bee Movie, B.C., etc.) I believe there's a kids' show (Possibly Octonauts?) with a robot anglerfish, and it's male.

So, yes. The female is the "default" of those species in the sense that it's the one people naturally think about. ... but our social bias comes back into play and we don't necessarily think of them as female.

So I think this reinforces the idea that the "default" nature of male animals is almost entirely our own society's lens, and not because males tend to be more biologically interesting. ApLundell (talk) 14:11, 4 August 2017 (UTC)

It makes sense to use the female only when sex/reproduction is involved. Now, as stated elsewhere, language is everything except logical, and gender is no exception. Gem fr (talk) 10:38, 4 August 2017 (UTC)

• Actually in a biological sense females are the default, at least in mammals. Our genes naturally produce a female body unless they are acted on by a substance called testis-determining factor, generated by the Y chromosome. Looie496 (talk) 14:47, 4 August 2017 (UTC)

indeed, obviously only female are required, parthenogenesis works. Male are thought to be evolution out of a female default type through various Sex-determination system, that prospered through Fisher's principle. But we know of them since about 1 century ago so they did not explain the language or other stuff. All mammals do not even use the XY sex-determination system; simply lacking Y chromosome won't make you a female, it will make you turner syndrom affected, while TSD is not enough to be a full male, there exist XX male syndrome. Gem fr (talk) 15:51, 4 August 2017 (UTC)

You mention the specific use of words like actor and steward - bear in mind that when these words originated there was no possibility of anyone except a male taking those roles. In Shakespeare's time only male actors were allowed on stage - and had to play the female roles as well. Wymspen (talk) 18:01, 4 August 2017 (UTC)

Plant identification

Oranmental plant

Another oranmental plant

Hello, these two pictures are used on Auburn Botanic Gardens with an uninformative caption "oranmental plant". Can anyone identify them? Are they possibly cherry blossoms, peach blossoms or plum (ume) blossoms? --PalaceGuard008 (Talk) 10:26, 4 August 2017 (UTC)

• The first one looks to me to be a Japanese cherry, a.k.a. Prunus serrulata. Tigraan^{Click here to contact me} 11:44, 4 August 2017 (UTC)

This definitively is a Cherry blossom (look at pictures provided in this article), coming from some sort prunus, but i don't know enough to specify which kind of the many close-related prunus it is; "cherries" are the most common "oranmental plant" (sic), and come to mind naturally when the purpose is to imitate a Japanese garden (as in ABG), but peach or plum, that also are close related prunus, cannot be ruled out.

for Plant identification a flower (alongside fruit) is one of the most specific, most useful part. If you can, providing a close range picture of flower will generally help.

Gem fr (talk) 12:20, 4 August 2017 (UTC)

Actually, I can say with a high degree of confidence, based on the morphologies here, that these are definitely both varieties of cerasus (the subgenus taxon, not the species) and very probably japanese cherries (Prunus serrulata, as Tigraan notes above), and not another variety of prunus. The trunk morphologies (despite being divergent between the two varieties of specimen here), the blossom morphologies (as best they can be made out) and the textures of the bark (particularly the distinct striations/lenticels of this taxon) are enough for a positive ID of cerasus, despite the low resolution defeating a precise ID of the variants. There's a lot of different cultivars in this group and they are broadly dispersed; all of the last four residences I've lived at, despite their being separated by hundreds or thousands of miles (and in some cases oceans) have had a variety of serrulata (although, to be fair, I planted the last one!), but a casual observer could be forgiven for not recognizing them as variants of the same species. Snow ^{let's rap} 21:08, 4 August 2017 (UTC)

Thanks very much! --PalaceGuard008 (Talk) 15:22, 7 August 2017 (UTC)

You're most welcome. :) Snow ^{let's rap} 01:43, 8 August 2017 (UTC)

How is H+ (aq) + H2O distinguished from H3O+ (aq)?

How do chemists determine whether or not a given ionic compound, observed only in aqueous solution, has had its hydrogen ions merge with water molecules to form hydronium, i.e. whether or not H⁺_(aq) + H₂O_(l) → (H₃O)⁺_(aq) has occurred? NeonMerlin 13:30, 4 August 2017 (UTC)

Not sure if you are asking about H+ alone (then, that's simple: it HAS occurred, period. There may be some occasional free H+, but not enough to worry about), or about weak acid Acid dissociation constant (in which case, these article will answer you)

Gem fr (talk) 13:57, 4 August 2017 (UTC)

I assume you're asking on an experimental basis. The hydronium article cites this very confidently worded paper describing how one of the proposed structures was established. I don't claim presently to understand some of the specifics. There has been enough back and forth with this, based on sophisticated processing of infrared spectra, that a person might go in to that paper with a skeptical prejudice, but this is the tool they have, and they can do a lot with it. Deducing a structure from numerical operations examining the period of vibrations detected in infrared is actually a little bit analogous to exoplanet discovery, and of course we know what remarkable things have been done there. Wnt (talk) 15:15, 4 August 2017 (UTC)

All models are wrong. Some models are useful. Chemical symbols written on paper is a model. The actual behavior of the atoms in an acid, aqueous solution is complex. Whether you represent the situation as "H+" or "H3O+" in a chemical equation depends more on what purpose you are writing the equation rather than either being a perfect representation of reality. --Jayron32 16:54, 4 August 2017 (UTC)

I am not an expert of chemistry but I think it may help. The H+ ion is very small and so possesses a great ionic potential (the φ of Fajan's rule). Water is a polar substance. Oxygen is slightly negatively charged. So the H+ is attracted to the oxygen, resulting a strong hydrogen bonding. It may make the bonding with more molecules making H5O2+, H7O3+ etc. The bonded water molecule is even more polar than a free water molecule. It may be bound with other free water molecules too. Free H+ is very rare in water solution. The link https://johncarlosbaez.wordpress.com/2013/11/29/water/ may be helpful. (If this is found wrong, please let me know by editing this answer)Sayan19ghosh99 (talk) 05:18, 6 August 2017 (UTC)

I should note we have a basic article Fajan's rules, though it mostly concerns whether compounds will be ionic or covalent, and a stub on ionic potential. Wnt (talk) 12:04, 6 August 2017 (UTC)

Particle, field interaction

Is it correct to say that when a particle crosses a field, it creates a force? 82.132.236.20 (talk) 15:29, 4 August 2017 (UTC)

It's more correct to say that a particle which exerts a force creates a field. See Field (physics). The field is the three-dimensional representation of a force. --Jayron32 16:49, 4 August 2017 (UTC)

the part See Field (physics) I concur. Force would obviously help, too.

The rest makes me exclaim "oh NO!".

A particle exerts a field whether it exerts a force or not!

Fields are related to potential force (a reason for them be also named "potential"), and do not represent actual, exerted, force.

Not the first time you post plainly wrong stuff, please be careful. Just sticking to providing ref is also a good way to protect yourself, you know. Gem fr (talk) 14:54, 5 August 2017 (UTC)

This is not the first time you tried to use pedantry to rudely makes yourself appear superior as though this were some kind of competition and that you somehow win because you got to slap someone down. Stay in your lane, bub. --Jayron32 16:45, 5 August 2017 (UTC)

It's not incorrect, but not precise enough to be sure you understand what you are talking about.

when a particle crosses a field, then it is subject to a force (if, of course, it is subject to this kind of field). Newton's third law implies that since the particle is subject to this force, then an equal and opposite force is also created; this one can be seen as the effect of the particle's own field. hence, you can say that the particule creates a force, as you did, but that's just a small part of the story.

Gem fr (talk) 14:54, 5 August 2017 (UTC)

What's the lowest air pressure Earth life can reproduce in?

Tardigrades can survive long stretches of hard vacuum but can't reproduce in it. Sagittarian Milky Way (talk) 15:30, 4 August 2017 (UTC)

Here is research published in 2010 : Exploring the Low-Pressure Growth Limit: Evolution of Bacillus subtilis in the Laboratory to Enhanced Growth at 5 Kilopascals

ApLundell (talk) 15:44, 4 August 2017 (UTC)

Just as a side note to this inquiry, it can be very hard to isolate variables in the study of such limiting factors, since manipulating the pressure may necessarily require changing the availability (and/or bioavailability) of certain elements critical to growth of a given organism. You can still determine the point at which reproduction is sub-optimal, stalling, or ceased altogether, but it's difficult to say (even with the kinds of highly sophisticated and refined methodologies such as those used in the research supplied by APLundell above) exactly what biophysical mechanics are causing the bottleneck. Snow ^{let's rap} 21:26, 4 August 2017 (UTC)

Evolutionary pressure in mating

If men chose women only due to their appearance and did not carry at all for their intelligence, would that put some evolutionary pressure driving female IQ down? That would be akin to women choosing strong men.--Hofhof (talk) 22:21, 4 August 2017 (UTC)

The less intelligent the male is, the less likely it is that he'll be able to choose any woman at all. Count Iblis (talk) 23:06, 4 August 2017 (UTC)

I think the answer would depend on whether or not appearance correlated with intelligence. If there were no correlation then the choice by males of attractive females would not put any "evolutionary pressure" on women not to be smart, and I have never heard of a correlation between female good looks and intelligence. Bus stop (talk) 23:45, 4 August 2017 (UTC)

This paper may provide the answer. The abstract mentions that physical appearance can contribute to fitness perception, and both parties select for high intelligence, whatever that may be. 50.4.236.254 (talk) 23:51, 4 August 2017 (UTC)

This title may also be of interest. RELATIONSHIP BETWEEN HYPOTHESIZED PSYCHOLOGICAL GENETIC FITNESS INDICATORS AND INDICES OF MATING SUCCESS. You may be able to find it through your public library. If not, you may alway contact the librarians and ask them for an Interlibrary Loan. Both articles contribute to the sexual selection theory. 50.4.236.254 (talk) 23:58, 4 August 2017 (UTC)

This one is specifically about humor as an indicator of intelligence, and that it is greater in males than females. "Humor ability reveals intelligence, predicts mating success, and is higher in males." For some reason, none of these titles are fully available in the database. So, if you have this issue, just check with your librarian and ask for an Interlibrary Loan. 50.4.236.254 (talk) 00:10, 5 August 2017 (UTC)

The question is not whether intelligence is sexually attractive. The question, as I understand it, is whether more-attractive women are generally more intelligent. We have not defined "intelligent". I think intelligence should be measured in accomplishments and abilities that are separate from the mating process. If we include in "intelligence" the ability to attract a mate through for instance good conversation, sense of humor, or musical or artistic abilities, then we are skewing the results to always find a high correlation between good looks and intelligence. I am taking as a given that men are attracted to the quintessential Marilyn Monroe. Bus stop (talk) 00:25, 5 August 2017 (UTC)

Attractiveness is relative. Count Iblis (talk) 03:30, 5 August 2017 (UTC)

"Perceived female intelligence as economic bad in partner choice." That is the title. You can find the full article on the ResearchGate. Apparently, the abstract suggests that female attractiveness cannot be substituted by intelligence, while male attractiveness can. Also, it seems to suggest that the more physically attractive the female is, the more intelligent she appears to be to the male. 50.4.236.254 (talk) 01:04, 5 August 2017 (UTC)

simple answser: no. Even if "If men chose women only due to their appearance and did not carry at all for their intelligence", (and that's a strong "if"), that would not put some evolutionary pressure driving female IQ down. Putting appearance above intelligence is quite different to specifically look for non-intelligence. Unless of course the more stupid you are, the more attractive, which i dare say not true without any reference (any objection? looks like 50.4.236.254 objects and require citation and reference for this one. eventhough several have aleready ). And, don't forget men preference are not the only factor, women have their word, too, and intelligence help them. I think that if a smart, not ugly, girl wants THIS guy, nobody less smart than her stand a chance, not even Marilyn Monroe. Gem fr (talk) 10:47, 5 August 2017 (UTC)

50.4.236.254 (talk) 12:23, 5 August 2017 (UTC)

"citation needed" is not supposed to be a trolling tool, you know. If you are not trolling specify which part require citation according to you. Otherwise retire in your ip swamp. Gem fr (talk) 14:02, 5 August 2017 (UTC)

It is not so much that I object. I am not sure if you are adding to what the provided research papers say in speculation or as a conclusion. Never mind. I think I misread your response. What you are saying seems in line with what the research papers suggest, which is that men place more importance on physical attractiveness than intelligence, and that higher physical attractiveness is linked to higher perceived intelligence, allowing stupid but beautiful women to be selected as well as beautiful, intelligent women to be selected. _{I don't know why Gem fr is accusing me of trolling. I am the only one who has provided actual research papers.} 50.4.236.254 (talk) 14:52, 5 August 2017 (UTC)

the question was "what if men did this", the provided reference answsered "they don't", which is good, but not answering the question any more that if you asked "what if i was falling from the 30th story of a building" and you only got answer "you are not". I hope my answer did.

That was because of twice posting very large spectre "citation needed", with no other words, where you could be more specific. my apologies

Gem fr (talk) 15:21, 5 August 2017 (UTC)

Oh. Then, the original question is speculative, and the answerers are encouraging the asker to ask speculative questions. 50.4.236.254 (talk) 16:28, 5 August 2017 (UTC)

"If men chose women...". This is about some hypothetical other universe isn't it? Some men may have the status/money/power to be able to have their choice to a large extent. In everyday life the picture is more like that men are altogether happy to find a woman, any woman, who will bat their eyelids at them. In the end it works out that men and women are able to choose those who are about equally fit. As to beauty, that is a good indicator of health. And being able to dance nicely, which is a major way people join up, is a good indication of intelligence. Dmcq (talk) 12:12, 5 August 2017 (UTC)

Men choose women in ISIS-land, or Boko Haram-land, or what's left of them. True, I don't know if they get to see their faces... I also don't know if the nonagenarians have more money to bid (or more incentive), which might tend to reverse the evolutionary effect. Wnt (talk) 19:01, 5 August 2017 (UTC)

50.4.236.254 (talk) 12:23, 5 August 2017 (UTC)

"Marry a pretty girl and she eventually turns ugly. Marry an ugly girl, get a few drinks in you, and she starts lookin' good!" -- Flip Wilson ←Baseball Bugs ^{What's up, Doc?} carrots→ 12:16, 5 August 2017 (UTC)

"Woman is the most powerful magnet in the universe... and all men are cheap metal." -- Larry Miller ←Baseball Bugs ^{What's up, Doc?} carrots→ 12:18, 5 August 2017 (UTC)

"If you want to be happy for the rest of your life / Never make a pretty woman your wife / So from my personal point of view / Get an ugly girl to marry you." -- Jimmy Soul ←Baseball Bugs ^{What's up, Doc?} carrots→ 14:34, 5 August 2017 (UTC)

Bugs, when the reference desks get shut down by the community partly because you have decided to make it a comedy club instead of a reference desk, will you feel even the slightest twinge of guilt? Or does your total immunity to any sort of peer pressure extend to a matching lack of introspection and self doubt? --Guy Macon (talk) 20:45, 5 August 2017 (UTC)

Guy Macon—I find nothing problematic about the above posts by Baseball Bugs. Bus stop (talk) 01:25, 6 August 2017 (UTC)

He'll then end up spending a lot more time with his ugly wife, so I guess he'll regret it. Count Iblis (talk) 21:14, 5 August 2017 (UTC)

August 5

Surface-to-surface missile

Recent news[5] got me thinking: has there been cases of surface-to-surface missiles or rockets launched at a ground target that managed to accidentally hit an airborne aircraft? Mũeller (talk) 04:47, 5 August 2017 (UTC)

Yes. Especially mobile man carried versions meant to hit enemy tanks are at opportunity also used to shoot down helicopters. --Kharon (talk) 05:05, 5 August 2017 (UTC)

I appreciate English is not your first language but I think you should make sure you understand key words like wiktionary:accidentally before you try and answer questions like this. Nil Einne (talk) 05:22, 5 August 2017 (UTC)

No accidentally accidental collisions. --Kharon (talk) 06:00, 5 August 2017 (UTC)

What does that mean? It's not even a proper English sentence. Akld guy (talk) 06:42, 5 August 2017 (UTC)

Note that User:Kharon changed the word after I drew attention to it. Deceitful. I have restored the erroneous word and struck it out. Akld guy (talk) 09:16, 5 August 2017 (UTC)

Let's not be too hard on him, guys. He's just trying to help; his intentions are good. His response might not answer my question but is still very much appreciated. Mũeller (talk) 07:56, 5 August 2017 (UTC)

(EC) As Akld guy said your reply is unclear. Are you saying there have never been any accidental hits of an airborne target from a surface-to-surface missile or rockets? If so, what's your evidence? This seems to be the sort of thing really difficult to rule out. While an aircraft being hit is often a big deal, even just a helicopter, still there have been a lot of conflicts and countries sometimes prefer to keep details under wraps especially in friendly fire cases to save face etc. And even more so if we go to the pre-internet age, and consider non catastrophic damage, it this could have happened without it being widely known. Nowadays you can also include drones (I'm thinking the more commercial ones than the military ones) to further complicate the situation. Note that accidental doesn't have to mean almost random. For example, in a confused combat situation, it would seem possibly for an aircraft and a careless person targeting ground targets to be both involved leading to the potential for such an accident. I mean the Taiwanese managed to hit a fishing vessel AFAICT, probably without targeting it [6]. Nil Einne (talk) 08:08, 5 August 2017 (UTC)

The guided versions are actually not that common. Mostused ground to ground missiles are unguided ballistic versions, the socalled Rocket artillery or multiple launch rocket system (MLRS). Then there are the person carried versions. And then the motorized versions. Apart from the ballistic versions these missiles are mainly aimed to fight armored vehicles and thus have a very limited range. Newer BGM-71 TOW for example have a range of only 4,5 km. Airplanes typically fly much higher - especially the big ones. Additionally these and the ballistic ones are rather slow, compared to anti-air missiles. So the chances are very limited even if these missiles would be used constantly everywhere, which they are not. The only theoretically threat for planes would be the ballistic ones, because they go quite high when shot on long distances. But their use is also rather limited in wartimes. Our Atmosphere is simply a to big space for accidental collisions. Even Airplanes almost never collide with other airplanes, nomatter they all fly near eachother day and night in rather narrow "sky streets" between the few airport. --Kharon (talk) 09:13, 5 August 2017 (UTC)

Who said anything about guided? Or aeroplanes? You yourself seemed to already agreed that helicopters in flight are airborne aircraft and no has disagreed with you on the point. In fact as I pointed out drones (in flight), even the more commercial like ones, would also generally be considered so. So I'm not sure why you're suddenly restricting the question to aeroplanes. The only point of contention was you original talked about intentional targeting (of helicopters) when I pointed out the OP specifically asked about an accidental hit so intentional/opportunistic hits are not counted. You then suggested (I think), it had never happened but asked what evidence you have for this. I pointed out this seems to be something which would be very difficult to actually prove conclusively didn't happen. If by your own agreement helicopters are airborne aircrafts that can be intentionally hit by surface to surface missiles and rockets, then it seems plausible this could also happen accidentally in the chaos and confusion of wartime. And that it may not have been widely reported, especially if it was minor enough that the aircraft survived (or it was unmanned) and the side who owned the aircraft would perhaps prefer it not to be widely known even more so if it was a friendly fire incident so the side who hit it also feel the same and even more so in the pre-internet and information revolution age so even if it was reported in some local paper, there's a far greater chance no one noticed and picked it up because of how unusual it is. Note also that almost never is not never. The OP did not ask if it was common, simply if it ever happened. A single incident would mean 'no accidental collisions' would not be true. P.S. I should go back to the fishing ship case. Yes that was a 2D instead of 3D situation. But it was also a, from what I've read, completely accidental firing in a non combat something which in itself rarely happens. Which IMO further highlights why we should be very careful about assuming hitting something unintentionally never happens. Nil Einne (talk) 11:50, 5 August 2017 (UTC)

Anyhow, The Rocket Propelled Grenade by Gordon L. Rottman says: "...hundreds of helicopters [were] damaged or destroyed by RPGs in Vietnam..." but that threat only came to widespread attention after the Battle of Mogadishu (1993), when two Sikorsky UH-60 Black Hawk helicopters were shot down by shoulder-launched unguided RPGs. Alansplodge (talk) 14:25, 5 August 2017 (UTC)

Our List of accidents and incidents involving the Lockheed C-130 Hercules says: "April 7, 1979 : C-130H 116 of the Libyan Arab Air Force was shot down by an RPG-7 round during take-off from Entebbe, Uganda, which was subsequently captured by Tanzanian troops during the capture of Kampala". However, all of the above were probably intentional, but who knows? Alansplodge (talk) 14:34, 5 August 2017 (UTC)

Direct eye contact

As you know, some shy or otherwise modest people avoid prolonged direct eye contact. Does it really has to do with human evolution where our simian and more distant ancestors perceived staring as a sign of aggression and/or intention to attack (as observed in some modern mammals)? That said, does the ultimate cause lie in evolution and not in shyness or other personal traits? Thanks. 212.180.235.46 (talk) 08:59, 5 August 2017 (UTC)

Simply, a predator with good eyesight will always keep his prey in focus, when it sneaks up or waits for it and ofcourse also in the assult or hunt. Thus all higher lifeforms instinctively judge staring at them as danger or threat. Shy people simply instinctively signal the opposite intend to everyone by avoiding eye contact. --Kharon (talk) 09:30, 5 August 2017 (UTC)

methink you should had rather provided shyness and Eye contact (i couldn't believe this one exists, but it does!) for reference, as suits the ref desk Gem fr (talk) 11:27, 5 August 2017 (UTC)

An early stage of training in Scientology requires the student to confront a coacher eye-to-eye for two hours without blinking despite whatever the coach may do to "bullbait" (distract) him. The church says this is useful. Blooteuth (talk) 14:43, 5 August 2017 (UTC)

You can't literally "not blink" for anything close to that time. ←Baseball Bugs ^{What's up, Doc?} carrots→ 15:49, 5 August 2017 (UTC)

Yes, but Scientology promises perfect vision. You can throw away your eyeglasses, you won't need them. I guess you can throw away your eyelids too. ;) Wnt (talk) 16:04, 5 August 2017 (UTC)

But first you have to throw away your brain. ←Baseball Bugs ^{What's up, Doc?} carrots→ 17:19, 5 August 2017 (UTC)

The Man Who Stared for 41 Minutes. Blooteuth (talk) 17:40, 5 August 2017 (UTC)

There are also cultural variations. I spent part of my childhood in Hong Kong and Singapore, in whose local (predominantly Chinese) cultures (so I later read, and as is suggested in Section 6.2 of Gem fr's first and 5 of his second linked references above) looking directly into another's eyes is usual only in situations of intimacy or dominance/hostility. Having internalised this, as well as being somewhat shy by nature, I am in Western culture often perceived as "shifty" because I do not make eye contact as often as the local norm. (Possibly as a side effect, I also rarely notice or remember others' eye colour.) {The poster formerly known as 87.81.230.195} 90.202.208.125 (talk) 20:36, 5 August 2017 (UTC)

August 6

How to determine electric and magnetic susceptibility

What are the methods to measure electric susceptibility (or polarizbility) and magnetic susceptibility of a given material experimentally? — Preceding unsigned comment added by Sayan19ghosh99 (talk • contribs) 05:23, 6 August 2017 (UTC)

See Electric susceptibility and this learning package. One might measure by constructing a capacitor with the test material as dielectric.

See Magnetic susceptibility which mentions experimental methods to determine susceptibility that include the Gouy balance and Evans (or Johnson-Matthey) balance. Blooteuth (talk) 14:27, 6 August 2017 (UTC)

Mounting Hole Diameter for M1.5 spring pin

I have a M1.5 spring pin and I'm trying to determine the correct hole diameter for it. So far I found this chart[7], which is for imperial sizes roll pins. I just need a similar chart but for metric sizes. Mũeller (talk) 06:06, 6 August 2017 (UTC)

Lokking at the imperial chart it looks as though the pins are sized for the quoted diameter, ie in your case 1.50mm. here's atable, it says 1.50 to 1.60 https://technifast.co.uk/recommended-hole-sizes Greglocock (talk) 06:21, 6 August 2017 (UTC)

Thanks! Mũeller (talk) 09:09, 6 August 2017 (UTC)

Resolved

Flowers' identification help

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All these pictures of flowers were taken at the Fitzroy Gardens Conservatory (apart from 6, which was outside in the gardens). Can anyone here help identify them please? --SuperJew (talk) 13:08, 6 August 2017 (UTC)

For convenience I should note the conservatory is in Melbourne near the southern extreme of the Australian mainland. I haven't made many attempts to identify flowers, so I should start by pointing at plant identification, which has some resources listed at the end; this guide to 50 most common families may also be useful; searching the web for australia flower identification turns up more specifically useful resources like [8] [9] (an image database, more for confirmation I would think). The government of Australia claims to have resources [10], but ends up pointing you at a selection of copyrighted "CD keys" written for archaic operating systems... with many other hits also, it looks like beating off the ads to find the usable resources is the tough part.

I would encourage people to try to explain how to do good plant identification with limited data we see in a case like this, and to upgrade the plant identification article to match. Wnt (talk) 15:08, 6 August 2017 (UTC)

"The government of Australia claims to have resources [11]" is a duplicate of the previous link. I don't think this was intentional since none of the links there point to anything to do with CD keys. Nil Einne (talk) 15:43, 6 August 2017 (UTC)

The fact that the conservatory is in Melbourne doesn't necessarily mean the plants are local, and the fact that they are in a conservatory means that the local weather isn't a factor either. --SuperJew (talk) 16:47, 6 August 2017 (UTC)

It looks to me like 1 could be some form of Aeonium, perhaps Aeonium arboreum. Definitely it looks like some kind of succulent. (P.S. If this right, I worked it out partially based on a Google reverse image search. It looked familiar but I didn't know what it was, but it looked distinctive enough it seemed worth giving it a shot. I tried the same thing on 4 but didn't see anything that hopeful although didn't look that carefully.) Nil Einne (talk) 17:20, 6 August 2017 (UTC)

@Nil Einne: That does look very promising (and reinforces my theory that they don't have to be local flowers). A Google reverse image search is a great idea! Thanks --SuperJew (talk) 17:31, 6 August 2017 (UTC)

I agree there's a reasonable chance they're not local since it doesn't seem to be the focus of the gardens or the conservatory (unlike say the Royal Botanic Gardens, Cranbourne). That said, I wouldn't say it's useless information to know it's in Melbourne, especially since we are talking about Australia and our article suggests they're state and city owned. I have a strong feeling given those circumstances, it's unlikely they're going to intentionally display anything that's a noxious weed (or whatever terms they use for problem invasive species) in Melbourne/Victoria unless they have a very good reason. And actually a quick search finds [12] which supports my suspicion. Nil Einne (talk) 14:48, 7 August 2017 (UTC)

I'm wondering maybe 2&3 are Impatiens walleriana?

Perhaps 4 is Hydrangea macrophylla, like in this pic?

Maybe 5 is a form of Fuchsia, perhaps Fuchsia boliviana or something similar? --SuperJew (talk) 18:13, 6 August 2017 (UTC)

No. 6 could be a variety of clivia. Richard Avery (talk) 07:41, 7 August 2017 (UTC)

2 & 3 are a variety of Impatiens hawkeri ("New Guinea impatiens"), I think. William Avery (talk) 11:49, 7 August 2017 (UTC)

Weight loss depression

Is depression a common occurrence in people who lose a lot of weight very quickly? Weisqusestion (talk) 14:05, 6 August 2017 (UTC)

“ Reduced nutrition can cause weight loss. The more hyperstimulated the body becomes, the more weight we can lose. These are just a few examples of how increased stress and anxiety can cause weight loss. ” — Jim Folk, Marilyn Folk, BScN., http://www.anxietycentre.com/anxiety-symptoms/weight-loss.shtml

50.4.236.254 (talk) 16:31, 6 August 2017 (UTC)

Lack of sleep can cause more calories to burn during the waking hours. Hence weight loss. Selective serotonin reuptake inhibitors, which are used to treat depression, may cause weight loss in older adults, but that's kind of speculative. Selective serotonin reuptake inhibitors (SSRIs) may produce side effects, including insomnia, nervousness, restlessness, and diarrhea. Nervousness and restlessness may produce more physical agitations, and hence, more fuel is burned. Diarrhea may cause malabsorption of nutrients. Depression is also heavily associated with bulimia.

Source: Jae Allen, http://www.livestrong.com/article/330360-why-does-depression-cause-you-to-lose-weight-even-though-you-eat-a-lot/

50.4.236.254 (talk) 16:46, 6 August 2017 (UTC)

The above sources suggest that the symptoms of depression may induce weight loss. It is possible that intentional weight loss may induce depression, as shown here. Source: http://abcnews.go.com/Health/w_DietAndFitnessNews/diets-depression-learn-mice/story?id=12357575 50.4.236.254 (talk) 16:58, 6 August 2017 (UTC)

Understanding temperature

The definition of temperature is

${\frac {1}{T}}={\frac {\partial S}{\partial U}}$

So in order to calculate $T$, one must express $S$ in terms of $U$.

The definition of entropy is

$S=-k\sum _{i=1}^{\Omega }p_{i}\ln p_{i}$

and the definition of internal energy is

$U=\sum _{i=1}^{\Omega }p_{i}E_{i}$.

But it should be clear that it is not necessarily possible to express $S$ in terms of $U$.

For example, suppose $\Omega =3,E_{1}=\epsilon ,E_{2}=2\epsilon ,E_{3}=3\epsilon$.

Then

$\{p_{1}={\frac {1}{3}},p_{2}={\frac {1}{3}},p_{3}={\frac {1}{3}}\}$ and $\{p_{1}={\frac {1}{4}},p_{2}={\frac {1}{2}},p_{3}={\frac {1}{4}}\}$

give the same value for $U$, but different values for $S$. So how can you define temperature? PeterPresent (talk) 14:58, 6 August 2017 (UTC)

Not an expert, but by my quick reckoning both of your examples have U = 2e. The first has evenly split energy states and entropy -k ln (1/3), while the second has -k ln (1/sqrt(8)). The second has less entropy because we have a good guess that a particle will be in the second energy state. Now of course S/U doesn't mean much by itself; we want the derivative of S/U, which means we have to look at how energy can increase. Which means that we need to look at how much S changes when energy is increased. And you're at kind of a funny point in that regard, like halfway to a negative temperature, in the sense that with one system you've defined three energy states and put the lower one as less likely than a higher state. So if we change 1/4 1/2 1/4 to say 1/4 3/8 3/8 the entropy drops from 1.03 k to 0.24 k, i.e. the entropy drops as energy is added increases to 1.08 k -- sorry, that isn't a suitable example after all -- ... at least if it is added this particular way. I'm not sure how you decide in what ratio of ways the energy is added. We'll need someone better at physics to go on from here... Wnt (talk) 15:29, 6 August 2017 (UTC)

Temperature is only well defined in thermal equilibrium, which means that you can only consider probability distributions that maximize S. Here you are free to impose constraints that prevent a global maximum from being reached, but you then have to specify these constraints (e.g. take a gas in a container of a fixed volume, the outside is a vacuum, if the volume were not fixed then the maximum entropy would be reached in the limit of an infinite volume). Now, in this case you have 3 probabilities, the sum of the probabilities is equal to 1, the internal energy provides another constraint, so there is one degree of freedom left. You should then fix this by either maximizing S or this is going to be fixed due to some other constraint the system is subject to. You then have a well defined S as a function of U, so the temperature is then well defined. Count Iblis (talk) 15:34, 6 August 2017 (UTC)

The formula for entropy expressed through $p_{i}$ pre-supposes that those probabilities $p_{i}=\exp(-E_{i}/T)/Z$ i.e. they obey Gibbs distribution ($Z$ is canonical partition function). Only in this case the (inverse) temperature can also be expressed as the first derivative from the entropy by the total energy. Ruslik_Zero 19:29, 6 August 2017 (UTC)

It makes sense that, given equal energies, entropy would reach a maximum as @Count Iblis: says. And as @Ruslik0: says, we expect to see a Gibbs distribution of energy states under normal circumstances. But are these things compatible, and can we derive the formula from the assumption? I suppose if we have a p_i, p_i+1, p_i+2 and we assume that the energy differences between them are equal, then converting x particles from p_i and p_i+2 to p_i+1 will involve no change in entropy. The total entropy from those three states only will be proportional to (p_i - x) ln (p_i - x) + (p_i+2 - x) ln (p_i+2 - x) + (p_i+1 + 2x) ln (p_i+1 + 2x). We want to minimize that negative number to maximize total entropy (-k multiplied by it). The derivative d/dx, for the limit of small x, should be - ln(p_i) - ln(p_i+2) + 2 ln (p_i+1) - p_i (1/p_i) - p_i+2 (1/p_i+2) + 2 p_i+1 (1/p_i+1) At least at a hasty consideration, I think the second terms of each derivative product cancel out in the end. Now we want an extremum of entropy, so this derivative should be 0, i.e. ln(p_i + ln(p_i+2) = 2 ln (p_i+1); taking e to the each we get p_ip_i+2 = p_i+1². This indicates an exponential relationship, at least, among the populations of energy levels, though it would take (at least) some normalization to get to the Gibbs distribution. Wnt (talk) 14:19, 7 August 2017 (UTC)

You can derive it quite easily using Lagrange multipliers. At the maximum the partial derivative of the entropy w.r.t. p_i should be a linear combination (independent of the index i) of the partial derivatives w.r.t. the constraint functions. The sum of the probabilities is one constraint function as this must equal 1 and the partial derivative if this function w.r.t. p_i equals 1. The expectation value of the energy is the sum over p_i e_i is another constraint function, the partial derivative w.r.t. p_i equals e_i. So, you then find that the logarithm of the probability is a linear function of the energy,so we're led to the Gibbs distribution. Count Iblis (talk) 19:37, 7 August 2017 (UTC)

What would happen if you brought a horse to a big pressurized lunar dome?

Would it learn the way to move from A to B with least energy or most speed? Would that gait involve jumping? How fast could it go? Sagittarian Milky Way (talk) 18:22, 6 August 2017 (UTC)

What have you found on Google so far? ←Baseball Bugs ^{What's up, Doc?} carrots→ 18:55, 6 August 2017 (UTC)

Somehow I doubt that there're any experimental results floating around (no pun intended, probably) regarding horses on the Mun... Whoop whoop pull up ^{Bitching Betty | Averted crashes} 07:37, 7 August 2017 (UTC)

[13] Sagittarian Milky Way (talk) 19:06, 6 August 2017 (UTC)

I strongly suspect that the only way we'd ever find out would be to actually take it there – from the literature and and lectures I've read/attended in the area of possible Crewed Mars missions, we're still uncertain as to how humans will best perambulate in Mars' gravity (very roughly twice that of the Moon's). One possibility might be a mentally broken, catatonic horse. It might also depend on whether the horse was taken as an adult or raised from embryo/early infancy on the Moon: Arthur C Clarke once suggested that a canary hatched in a zero-gravity space station would easily adapt to flight there, but I don't think he had any experimental data. {The poster formerly known as 87.81.230.195} 90.202.208.125 (talk) 20:51, 6 August 2017 (UTC)

Language peeve: twice that of the Moon's what? that in this phrase means 'the gravity'; and I don't think it's normal English to say "the gravity of the Moon's" in the same way as "a friend of Alice's". Or – since Moon's is parallel in form to Mars's – maybe it's twice [the something else] of the Moon's [gravity]? —Tamfang (talk) 05:37, 7 August 2017 (UTC)

Some thoughts:

1) We do know that horses are capable of adapting their gait to different situations. For example, they learn to move more slowly when wading through water, or to step higher when walking through thick mud or heavy snow.

2) So, it's reasonable to assume they would also adapt their gait to less gravity.

3) However, bouncing higher into the air with each step might be scary, causing them to use less force to take smaller steps. This would be especially true if they fall over, say by rotating when airborne, when using full force.

4) They may eventually learn to use full force again safely. Or, their muscles may atrophy from less use. Perhaps something in-between is the most likely outcome. StuRat (talk) 19:49, 7 August 2017 (UTC)

Wireless telephone in 1922

Sinclair Lewis mentions wireless telephones in his novel Babbitt, published 1922. What does he mean by that? The wireless telephone article redirects to cordless telephone, but these telephones were not invented until the 60s. Extract:

"Though he no longer spoke of mechanical engineering and though he was reticent about his opinion of his instructors, he seemed no more reconciled to college, and his chief interest was his wireless telephone set. "

--Hofhof (talk) 20:56, 6 August 2017 (UTC)

The device is closer to the mobile radio telephone of the 1950s and 1960s. These were VHF voice radios, about 150MHz and FM modulation, which could be used from within a moving car. They were also simple enough to operate, with simple crystal-controlled channel selectors, to not require "tuning" and thus a separate operator. They connected to a regional base station and operator who was able to patch them into the national telephone network. Andy Dingley (talk) 21:03, 6 August 2017 (UTC)

Wireless telephones existed by the 1910s. Here's a 1916 song about the subject.[14] ←Baseball Bugs ^{What's up, Doc?} carrots→ 21:44, 6 August 2017 (UTC)

And here's a 1914 photo of one (not quite a "mobile" phone):[15] — 2606:A000:4C0C:E200:4890:FAC5:8AED:1CC9 (talk) 23:09, 6 August 2017 (UTC)

In that era, telephones was a word used for what we now call headphones, at least in Britain. See the testimony of Harold Bride, wireless operator of the Titanic, when he gave evidence at the American inquiry into the sinking. The relevant testimony is here and you need to scroll up about one screen page from the bottom. Akld guy (talk) 00:31, 7 August 2017 (UTC)

And again, here, again about one page up from the bottom. Akld guy (talk) 01:16, 7 August 2017 (UTC)

@Baseball_Bugs, after I listened to the song you've posted, I said: "This guy is a genius. He provided an answer, an incredible historical reference and an entertainment. I would like to get the lyrics, though. Can you do it? Thanks, - --AboutFace 22 (talk) 12:36, 7 August 2017 (UTC)

We have an article: Hello, Hawaii, How Are You?. The wireless telephone in question is (presumably) this. AndrewWTaylor (talk) 13:21, 7 August 2017 (UTC)

Resolved

With kudos and thanks to Baseball Bugs for his pertinent, well referenced response from the world of entertainment. Blooteuth (talk) 14:41, 7 August 2017 (UTC)

August 7

Hearing aid battery tester.

I've always wondered how this little devil works[16]. This link is to an amazon.com device that costs very little. What you do, you put a battery like 312 on the metal plate with the positive end down, then press it with you index finger and if the battery is full of charge, the other part, the display, will show a grid, a set of about 30 parallel bars. If they run all the way to the top, your hearing aid is fine. Otherwise it goes to the waste basket.

How does it work?

Thank you, --AboutFace 22 (talk) 01:53, 7 August 2017 (UTC)

If it is the usual kind of battery tester, it connects the two ends of the battery across a given resistance and measures the amount of current that flows. Looie496 (talk) 02:58, 7 August 2017 (UTC)

There is no circuit, unless it is though my body, besides my body is on an isolator, the floor. --AboutFace 22 (talk) 12:38, 7 August 2017 (UTC)

Well if there is no circuit then it cannot work. The picture is fairly low res, but AFAICT, and also based on the user comments, there seems to be a plate at the bottom and a clip to the side-up (in the direction shown in the picture). The bottom plate touches one terminal of the battery and the clip touches the other so there is a circuit in the device through these 2 terminals connecting to the 2 terminals on the battery. Your finger is mostly irrelevant, it's just need to apply pressure to ensure the battery makes good contact with the two terminals/contacts on the device. Nil Einne (talk) 14:20, 7 August 2017 (UTC)

This video with a Malaysian or Singaporean presenter [17] of a very similar device seems to confirm my suspicion. You can clearly see the clip, and also see it doesn't work until the battery connects to both the plate on the bottom and the clip on the side-up. Nil Einne (talk) 14:25, 7 August 2017 (UTC)

BTW, maybe in your version the clip is harder to see than the Amazon or video one. I suggest you look carefully and you will see there is another contact point. Nil Einne (talk) 16:37, 7 August 2017 (UTC)

Public service announcement: please recycle dead batteries. Don't throw them in the trash. Many batteries contain toxic substances, and in any case recycling allows their components to be reused. --47.138.161.183 (talk) 16:08, 7 August 2017 (UTC)

@Nil Einne, you are right. Now I begin to figure out how many batteries I've discarded because I never touched that little protrusion in my ignorance. That video shows exactly the device in question. --AboutFace 22 (talk) 19:48, 7 August 2017 (UTC)

How hard of a hit to the testes would be needed to temporarily incapacitate a gorilla?

What about a chimpanzee? Sagittarian Milky Way (talk) 04:41, 7 August 2017 (UTC)

Approximately 3 SMWs. 1 SMW is about what I feel like doing when I read one of these questions. Greglocock (talk) 05:07, 7 August 2017 (UTC)

Only 1? You're kinder than me..... Nil Einne (talk) 14:26, 7 August 2017 (UTC)

How do you know what 1 SMW is if your only information is that it's a third of that needed to incapacitate a gorilla? --129.215.47.59 (talk) 15:28, 7 August 2017 (UTC)

I did find a demonstration of the experiment: [18]. I believe the force there is approximately equal to 1 SMW. --Jayron32 16:34, 7 August 2017 (UTC)

Well that information is enough to know it's not enough. It's not necessary to know precisely how much it is. Nil Einne (talk) 16:35, 7 August 2017 (UTC)

Out of curiosity, do you need an answer very very very very very very very quickly? If so, good luck. Hayttom (talk) 17:53, 7 August 2017 (UTC)

And for any needed repairs, there's always Gorilla glue. ←Baseball Bugs ^{What's up, Doc?} carrots→ 18:08, 7 August 2017 (UTC)

More like a prosthetic limb or three. Sagittarian Milky Way (talk) 18:24, 7 August 2017 (UTC)

"Ekʉa álulɔ ntile lé ebam" - a spear is never forged while a gorilla is screaming at you. Oddly, this is the only thing Google indexes for "self-defense against a gorilla", which suggests that many folks online have not taken this proverb to heart, or really aren't expecting gorilla warfare. Wnt (talk) 21:13, 7 August 2017 (UTC)

The incapacitation is supposed to happen via a severe pain reflex, but then wild animals will typically have more effective reflexes, so the gorilla may end up killing you in a strike that is triggered by that supposedly incapacitating pain reflex. Humans have bad reflexes and it is getting worse because children are not paying outside as frequently as they should. Many children today get broken bones due to falls, that's because by playing video games all they long they have not trained the reflexes they get when they are about to fall to prevent the fall or to break the fall. Count Iblis (talk) 19:28, 7 August 2017 (UTC)

Possibly useful context is that a gorilla's testes are slightly smaller than a human's [19] whereas a chimpanzees, that source says, are three times larger. It looks like Straight Dope struck out on this one, with nothing but guesses and humor. Wnt (talk) 21:19, 7 August 2017 (UTC)

Guesses and humor? No shit? Wonder where I've seen that before? If it's good enough for Uncle Cecil, it's good enough for us, I guess. --Jayron32 22:32, 7 August 2017 (UTC)

Pot with water, time to boil

If you are heating a pot with water and stir it with a spoon, would that change significantly how fast the water starts to boil/how heat is transferred? --Hofhof (talk) 12:36, 7 August 2017 (UTC)

This doesn't address your question (hopefully that will come later) but I think that a third option of putting a lid on the pot to reduce evaporation and leaving convection (the hot water should rise and the cold water should fall) to take care of the mixing would be the fastest (and most environmentally-friendly option). I'm looking for sources now but I expect to fail. --129.215.47.59 (talk) 12:47, 7 August 2017 (UTC) I've given up looking and this was the best I could find (it doesn't meet Wikipedia criteria for sources): it says there's 2.8% improvement for adding a lid but doesn't address stiring. --129.215.47.59 (talk) 13:09, 7 August 2017 (UTC)

There are multiple stages of boiling. If the water is still, you will see that the bottom of the pot will form bubbles first (assuming the pot is only heated at the bottom). That is because the water nearest the heat source is hotter and reaches boiling temperature first. Eventually, all the water will reach boiling temperature and the bubbles will form throughout the water. This is called a rolling boil. If you stir the water, you will keep moving the hottest water at the bottom with the cooler water on top (assuming you do a good job at stirring). So, you will delay the partial boil where the bottom forms bubbles, but the pot isn't entirely boiling. You will not significantly change the time to reach a full rolling boil. From a very technical and pointless point of view, you will be adding energy to the water by stirring, which will decrease the time to a rolling boil. But, it will not be significant. For example, you cannot make a pot of water boil just by stirring it extremely fast. Even with a power tool, you can't stir it fast enough to get it to boil. So, all you are really doing is keeping the pot mostly at the same temperature instead of hot on bottom and cold on top. 209.149.113.5 (talk) 12:49, 7 August 2017 (UTC)

Generally speaking you will slow boiling, because you will increase the rate of heat loss to the air. In fact if you have a weak enough heat source, vigorous stirring may be enough to prevent the liquid from boiling at all. Looie496 (talk) 13:35, 7 August 2017 (UTC)

Thompson's not pointless paper "An Experimental Enquiry Concerning the Source of the Heat which is Excited by Friction" of 1798 led Joule to propose this kinetic theory of heat: "wherever mechanical force is expended, an exact equivalent of heat is always obtained". Merely by stiring vigourously you may add heat to the water, and can eventually even boil it. If precautions are taken to eliminate loss of heat by conduction, convection and evaporation, the experiment can be done to measure the Mechanical equivalent of heat, exactly what Joule did in 1845, and still a valid result. Blooteuth (talk) 14:12, 7 August 2017 (UTC)

It is correct that moving warmer water to the top of the pot will increase the rate of heat loss to the air. In the same way, moving cooler water to the bottom of the pot will increase the rate of heat absorption by the water. 209.149.113.5 (talk) 17:20, 7 August 2017 (UTC)

Why was the helical structure of DNA such a big deal?

Resolved

I can understand why now, with the knowledge of protein structures and how they might fit into the major or minor grooves and how DNA is compacted and unwound, knowledge of the helical structure of DNA is very important but back in the 50s was this as clear? Is the big deal just because it's digestible by the public like E=mc^2 and Dolly the Sheep? Was it seen as a big deal in the 50s or did it become a bigger deal in hindsight when later developments were seen to hinge on understanding the helix? What about discovery of the four main nucleotides themselves; isn't that worth an even bigger fuss? --129.215.47.59 (talk) 12:43, 7 August 2017 (UTC)

Understanding how cells store genetic information was/is the big deal. The DNA model has a double helix structure. Knowing this was a big step to understand it. This is the mainframe. Phoebus Levene's discovery bewtween 1909-1929 of the nucleotides was not enough to know how information gets processed. Nor was enough to isolate DNA for the first time as Friedrich Miescher did in 1869. There was a piece of the puzzle missing until Watson and Crick came along.--Hofhof (talk) 12:55, 7 August 2017 (UTC)

But why was the Watson/Crick part of the puzzle considered so big? I think they might be household names but I've no idea who discovered the nucleotides and I don't see the difference in significance. 129.215.47.59 (talk) 13:11, 7 August 2017 (UTC)

X-ray diffraction studies showed that DNA had a regular, repeating structure as early as 1937 - see William Astbury. In 1950 Erwin Chargaff discovered that the amounts of adenine and thymine in DNA were roughly the same, as were the amounts of cytosine and guanine - see Chargaff's rules. Rosalind Franklin concluded that the structure of DNA was a helix by January 1953 and in February 1953 Linus Pauling proposed an incorrect triple helix structure. But the "big deal" was Crick and Watson's announcement in April 1953 of a molecular structure which was consistent with all the known properties of DNA and also explained how the regular physical structure of DNA could still encode genetic information which varied from one individual and one species to another. Gandalf61 (talk) 13:20, 7 August 2017 (UTC)

• (Edit conflict) See History of molecular biology#History of DNA biochemistry. The important part of the discovery was not that DNA was a helix, but that it was doubled and made of paired bases. This meant that it could easily split in half and duplicate itself. This was a surprising discovery at the time - biologists guessed DNA played a role in inheritance thanks to the Hershey–Chase experiment, but they didn't know what its structure was (a common theory was triple-stranded DNA, but that didn't really work), and that meant they couldn't work out how genetics actually worked. Once it was clear that DNA had a simple structure and could copy itself easily, it became clear that it was the foundation of the genetic code. Our article on Watson and Crick's paper, Molecular Structure of Nucleic Acids: A Structure for Deoxyribose Nucleic Acid, has a little more information. Smurrayinchester 12:56, 7 August 2017 (UTC)

Oh right, thanks; that does seem like it explains the significance a lot better. I think my query can be considered resolved. Thanks again. 129.215.47.59 (talk) 13:14, 7 August 2017 (UTC)

As they said themselves in the paper (see Smurray's link): "It has not escaped our notice that the specific pairing we have postulated immediately suggests a possible copying mechanism for the genetic material". --69.159.60.147 (talk) 19:43, 7 August 2017 (UTC)

Nitpick: saying that DNA "copies itself" isn't quite correct. That's what DNA polymerase does. Now sure, the DNA in organisms contains the gene for DNA polymerase (actually several, in most organisms), but it has to go through the whole transcription process to produce the enzyme. RNA, on the other hand, can duplicate itself. Numerous ribozymes are found in cells, including the ribosome. The realization that ribozymes are essential to most cells gives a lot of evidence for the RNA world hypothesis, which asserts that life once used RNA as its genetic material. It eventually switched to DNA as the storage medium because DNA is more stable, but kept most of the RNA-based machinery, which is why life today still uses RNA as an intermediate in gene expression. Of course I'm not suggesting that the discovery of DNA's structure wasn't important; indeed, its structure explains why DNA is more stable. --47.138.161.183 (talk) 15:51, 7 August 2017 (UTC)

Feynman Lectures. Exercises. Exercise 10-3 JPG. Lecture 10

. .

...

10-3. An earth satellite of mass 10 kg and average cross-sectional area 0.5 m² is moving in a circular orbit at 200 km altitude where the molecular mean free paths are many meters and the air density is about 1.6 x 10 ^-10 kg m^-3. Under the crude assumption that the molecular impacts with the satellite are effectively inelastic (but that the molecules do not literally stick to the satellite but drop away from it at low relative velocity), calculate the retarding force that the satellite would experience due to air friction. How should such a frictional force vary with velocity? Would the satellite's speed decrease as a result of the net force on it? (Check the speed of a circular satellite orbit vs. height.)

—  R. B. Leighton , Feynman Lectures on Physics. Exercises

I have found answers to the first two questions png.
Don't understand last question. There is the retarding force in opposite direction to the velocity. So magnitude of the velocity must decrease. Then the satellite must deorbit and go to an elliptical spiral orbit (If the retarding push were single, then the apogee would be at this point.). At this moment we do not know that the atmosphere is exponential, so I suppose that density = const. Why does Feynman think that the satellite will remain in a circular orbit (his last sentence in brackets)? Username160611000000 (talk) 13:50, 7 August 2017 (UTC)

Because the total drag experienced per orbit is very small, it is possible to use a quasi-steady state approximation and model the satellite as following a series of circular orbits whose radius is very slowly decreasing over time. As you probably know, a circular orbit with a smaller radius must also have a faster velocity. In effect, deorbiting the satellite due to drag actually causes it to gain velocity from the Earth's gravity well. Dragons flight (talk) 15:10, 7 August 2017 (UTC)

Can biomass be sold in bulk to thermoelectric plants?

I have mainly interest on the situation in the UK, but knowing about other countries is OK too. So, if someone has biomass (like paper, or a farmer with tonnes of dung) in excess, as residual stuff, would a thermoelectric plant buy it, in the same way that other commodities are traded? Can such a plant operate with different types of inflammable biomass? That is, can you throw paper, dung, sawdust or chipped wood? Does this make financially and ecologically sense? --B8-tome (talk) 17:44, 7 August 2017 (UTC)

One big difference is water content. Dry biomass, like sawdust, can be burnt to release energy (although it's so flammable it can be an explosion risk). That wouldn't work with wet biomass, like dung (you could dry it first, but that would use more energy than you get from it or create a big stink if you spread it out in the sunlight). Allowing it to decompose to generate heat and methane, which you would collect and/or burn, would be a better option there. Farmers might do better to use manure as fertilizer, though, unless there's a concern over spreading disease that way (either to humans of other animals).

Note that a steam turbine is one technology that's remarkably flexible as to the fuel. You can use nuclear energy, geothermal energy, or any flammable material to make the steam from water, then extract energy from it. However, you would need a different mechanism to store, load, and burn the fuel, say with sawdust versus methane. StuRat (talk) 18:07, 7 August 2017 (UTC)

Often, biomass fuel is singly-sourced to a specific industry or even specific source within that industry for a regular supply chain, see for example, Bagasse, one of the more common biofuels, which is used at the site of production as a fuel source. --Jayron32 18:45, 7 August 2017 (UTC)

Oh, and I should mention that using biomass for fuel is considered to be carbon-neutral and renewable energy, as it's assumed that those materials would decompose and release carbon dioxide and methane on their own, but doing so in a way where we collect energy from them during the process doesn't release any more, unlike when we burn fossil fuels. StuRat (talk)

A typical thermoelectric plant is setup to handle a specific fuel in terms of its storage, loading, and the handling of any residual waste. It is often not too difficult to retrofit a plant that runs on one fuel to run on another fuel, e.g. converting a coal plant to run on natural gas is common. However, the typical plant is unlikely to want to accept an occasional pile of random waste. The won't be set up to handle it, and won't want the extra hassle. The exception may be plants designed to burn municipal waste. In some areas, most residential and commercial trash is sent to incinerators rather than landfills. Those incinerators can be setup to generate electricity (though usually only a small fraction of a country's needs) and are likely to have the flexibility to accept a wide range of materials. Dragons flight (talk) 19:40, 7 August 2017 (UTC)

Miscanthus x giganteus is a biofuel/bio-engergy crop subject to much recent interest and research. You can harvest the dried crop, and run it through a pelletizer to make pellet fuel. Since Miscanthus can be grown in a carbon-negative manner, burning this fuel results in no net increase in atmospheric CO2. Put simply, you can grow grass as a carbon sink, then burn it for heat/energy, and still sequester more carbon in the soil than you've released in to the air. See here [20] for a freely accessible research article detailing the carbon dynamics of Miscanthus in central IL. There really is tons of research on this, see also here [21] for another good set of references and context. There is considerable interest in the UK and EU for developing this type of market. I don't know much about actual extant power plants in the UK but in principle they can be adapted to burn pellet fuels. See here [22] for some information on EU power generation via pelletized biofuel. SemanticMantis (talk) 21:24, 7 August 2017 (UTC)

• Waste-to-energy may also lead you to interesting places for your research. --Jayron32 22:31, 7 August 2017 (UTC)

+

Decades ago I saw an abandoned waste-burning power generating pilot project. It had a conveyor belt which fed municipal waste into a furnace , where it was burned along with natural gas to heat a boiler to generate a small amount of power for a utility. The idea was to reduce the need for landfill while producing power. I don't recall that they addressed the issue of environmental pollution from burning random plastic and other waste items. The project was abandoned because it required too much labor to chisel impurities off the grate (think clinker fro a coal furnace, but worse.) At the time it did not seem to my naive view to be an insuperable problem, but the utility would have rejected "free" biomass since it had handling and cleaning problems which made it more expensive to use than traditional fuels. In the 1970's the US government developed the "MIUS" or modular integrated utility system, which would be a neighborhood-scale utility plant which would burn the trash to generate power, while using the energy to purify the sewage, and return the purified water for household use, while providing heating and cooling. It seems to have failed the failed the "NIMBY" (not in my backyard) test since people feared the fumes it would emit. Edison (talk) 02:49, 8 August 2017 (UTC)

How much heat does a CCFL output?

Can someone help determine the amount of heating power that applies to a CCFL as used in LCD displays? Those I've tested consume 0.4 A at 12 V (4.8 W) and that includes the energy lost by the inverter. If the inverter is 80% efficient then 3.8 W are passed on to the lamp which I guess produces X amount of light and Y amount of heat. I don't think the length is important to know; only the percentage that goes to light (or heat) --145.255.246.78 (talk) 20:52, 7 August 2017 (UTC)

Warning: I asked a similar question about light vs heat efficiency of a bulb here before. Everyone refused to answer because the consensus was that all energy becomes heat so the bulb outputs only heat and light is just a side effect. 2600:1004:B108:9BD0:F9E8:F75:A476:CF30 (talk) 22:09, 7 August 2017 (UTC)

I'm specifically interested in the heat experienced by the bulb itself, not its environment, so photons that leave the bulb don't count much towards the heating of the bulb. --145.255.246.78 (talk) 05:26, 8 August 2017 (UTC)

This article Seems to lead where you're looking, and it has footnotes to other places to help your research. --Jayron32 22:30, 7 August 2017 (UTC)

Could you determine the heat current going to the bulb as opposed to the light current?Edison (talk) 02:28, 8 August 2017 (UTC)

Thanks but I'm interested in CCFLs (from LCD monitors) not CFLs. 145.255.246.78 (talk) 05:29, 8 August 2017 (UTC)

Mystery caterpillars (San Diego)

What is this pink caterpillar, and what's it doing on a clump of seaweed on a sandy beach? (Assuming it is a caterpillar; if not, what is it?). I also found a similar looking yellow one on a sidewalk a few weeks ago. What species are these? 169.228.146.121 (talk) 22:50, 7 August 2017 (UTC)

Do scientists know what type of bugs are required to colonize the body for healthy living?

Keeping clean may sound like a good idea, but hyper-cleanliness may mean that the wrong type of microorganisms get on the body. Playing in mud is probably not practical and disgusting, and drinking toilet water is a good way to die by dysentery. So, is there a middle ground to get the RIGHT type of bugs for healthy living, or are some individuals doomed no matter what? 50.4.236.254 (talk) 22:51, 7 August 2017 (UTC)

Technically, everyone is doomed. ←Baseball Bugs ^{What's up, Doc?} carrots→ 01:32, 8 August 2017 (UTC)

Everyone has to die of something.--Jayron32 01:53, 8 August 2017 (UTC)

The article Microbiota is where you want to start your research.--Jayron32 01:53, 8 August 2017 (UTC)

August 8

Escalators changing directions

One day the escalator is going up and the next day down. Why? Anna Frodesiak (talk) 02:13, 8 August 2017 (UTC)

Because somebody flipped the switch that reversed it's direction.--Jayron32 02:23, 8 August 2017 (UTC)

Excellent answer, Jayron32. :) Now, why did they flip that switch? Anna Frodesiak (talk) 02:32, 8 August 2017 (UTC)

It's possible that they adjust the direction to match traffic flow. So, for example, if they have 3 escalators, they may have 2 going up and one down when people are coming into the building, and the reverse when they are leaving. Unlike changing the directions on roads, this operation should be fairly simple. Just put up a barrier blocking people from getting on, wait until everyone is off, then flip the switch and remove the barrier. StuRat (talk) 02:41, 8 August 2017 (UTC)

They might do this at large sports venues, for example. ←Baseball Bugs ^{What's up, Doc?} carrots→ 02:51, 8 August 2017 (UTC)

Yes, it's a standard thing to do at locations like that, and similarly in public transit stations where some escalators will run one way in the morning peak and the other way in the evening. (Details will depend on the traffic at the specific location, of course.) With the ones that I've seen, there may be a small sign telling staff what time each day to change it, next to the up/down switch (which is key-operated, by the way). But Anna says this isn't the case she's asking about. --69.159.60.147 (talk) 05:16, 8 August 2017 (UTC)

I'm not sure that's it. I see in lots of malls, a pair of escalators switching up to down and down to up. These are quiet malls with no traffic-flow reason to do this. Could this be about the gears and evening out wear from continuous single direction usage? Or is it psychological to shake up and wake up the people, or make them flow in a different direction when they disembark, like to make them see now products? Anna Frodesiak (talk) 02:58, 8 August 2017 (UTC)

They also switch up directions so that the escalators wear evenly. .--B8-tome (talk) 02:52, 8 August 2017 (UTC)

Edit conflict. I just guessed what you wrote! See above. Are you sure though? Thanks. :) Anna Frodesiak (talk) 02:58, 8 August 2017 (UTC)

If you want to be sure, you'll have to ask the building management people. --69.159.60.147 (talk) 05:16, 8 August 2017 (UTC)

Neuroscience question

Is it possible to remove consciousness (like the feeling of under anaesthetic), but keep your body alive and functioning normally in everyday life? I.e. is it possible to turn a person into a meat machine? Why does consciousness even exist? If materialism is correct there shouldn't be any consciousness. It would reduce a lot of suffering in this world if people can do this, unless dualism/idealism is correct. Money is tight (talk) 05:31, 8 August 2017 (UTC)

Cooling a CCFL bulb without straining the glass

I want to make a floodlight from salvaged CCFL lamps. Despite their name, they do generate heat and I'm going to be using them in high-density so I need to cool them (their efficiency drops off beyond about 30 °C) and I'd like to do it passively if possible (mostly because of the noise). The way I'm considering doing this is affixing the glass tubes to an aluminium panel (thickness not determined), possibly using thermal adhesive or possibly a cheaper adhesive. My concern is that with cooling on one side of the glass tube, it could lead to stress and fracturing which would destroy the tube. Is that a valid concern? --145.255.246.78 (talk) 06:23, 8 August 2017 (UTC)