Wikipedia:Reference desk/Archives/Science/2021 December 5

= December 5 =

Polymers and viruses classifications.
Weird, I been waiting almost 24 hours for SCSBot to add Dec. 4. So polymers have like a 3 by 2 classification. Polymers can be thermplastics, thermosets, and somewhat overlap elastomers. Polymers can also be amorphous or crystalline. However, elastomers are amorphous-only. But I'd like some crystalline examples.


 * Amorphous thermoplastics: Glue.
 * Amorphous thermosets: epoxy resins, polyurethanes.
 * Amorphous-elastomers: rubber bands, tires, and contact lens.

But what are crystalline examples, for thermoplastics and thermosets? The only 1 I have is glass. But is that a thermoplastic or thermoset? Elastomers can also sometimes be a thermoplastic or thermoset. Thermoplastics I believe have no cross-linking, thermosets high-cross linking, and elastomers low-cross linking.

I'm also looking for a categorical classification for viruses. The only 1 I can think of is enveloped viruses vs. non-enveloped viruses. Are there any others? Thanks. 67.165.185.178 (talk) 00:57, 5 December 2021 (UTC).


 * Virus classification Sagittarian Milky Way (talk) 01:50, 5 December 2021 (UTC)


 * Not a chemist, but since nobody else is replying, I'll mention that I looked at the articles liquid crystals, kevlar and spider silk, which sound to my naive mind like possible examples of crystalline polymers. The article on glass begins "Glass is a non-crystalline ...", which throws me off, but I don't want to tell you you're wrong, since words can have two meanings. Card Zero  (talk) 16:29, 5 December 2021 (UTC)

Bird rabies?
Are birds susceptible to rabies (or any other transmissible neurological disease which causes aggression)? If so, can they transmit it to other birds and/or to people? (No, I have NOT been bitten by a bird -- I've watched a film where lots of people were!) 2601:646:8A81:6070:E03D:3B7A:ECA5:DA02 (talk) 06:28, 5 December 2021 (UTC)


 * From our article on rabies transmission: "Birds were first artificially infected with rabies in 1884; however, infected birds are largely, if not wholly, asymptomatic, and recover." Source. For this to occur naturally, a bird would have to either be bitten by or eat a rabid mammal first; in many cases of the former I suspect the bird would die from the wound before any viral CNS involvement (I'm guessing this is also why rabies in small terrestrial mammals is virtually never found). As for the latter, antibodies to the virus have been recorded in predatory and scavenger birds, but they seem to be clinically asymptomatic.
 * Neuroinflammation and/or neurodegeneration from any cause is capable of producing behavioral changes, including aggression, but these can vary significantly between individuals. Even rabies has multiple disparate outward presentations. The same is true for BSE and sad horse disease. So a particular disease would have to have a pretty specific mechanism to produce consistent behavioral results. I did find some reports of Mycoplasma gallisepticum infection decreasing aggression in male finches, but then this illness also causes lethargy so it's more likely these sick birds just didn't have the energy to get in fights. My brief search didn't return anything else documenting a neurological infection inducing aggression in birds. JoelleJay (talk) 08:11, 5 December 2021 (UTC)
 * If you've only seen the movie and not read the article you may not be aware that The Birds was inspired by real life events. The real life birds went crazy due to algae poisoning, though, which is not transmissible, and they didn't organize themselves into planned attacks like in the movie. Matt Deres (talk) 15:20, 5 December 2021 (UTC)
 * There are several behavior-altering parasites with birds as hosts: however, they all alter the behavior of the birds' prey rather than that of the bird itself. The default bird activity of flying around eating stuff, and depositing it again in random places, serves parasites very well without the need for any alterations such as aggression. The evolutionary pressure might be different if birds were large and durable, had teeth and were bitey. Rabid pterosaurs are a plausible concept. One might also wonder about ostriches, but I think they tend to kick rather than peck, which removes the transmission vector through saliva. Card Zero  (talk) 16:09, 5 December 2021 (UTC)

Russian nuclear missiles
In the early 1960s, were the warheads on Russian sub-launched nuclear missiles single-point safe? In other words, might an on-board reactor explosion have set off the warheads and caused a full-scale nuclear explosion, as Captain Vostrikov claimed? 2601:646:8A81:6070:E03D:3B7A:ECA5:DA02 (talk) 06:43, 5 December 2021 (UTC)
 * I think the design of the nuclear warheads that were the payload of the R-13 missiles aboard the K-19 is still a guarded secret. No nuclear reactor has ever "exploded", other than steam explosions; the worst accidents have been meltdowns. A nuclear explosion close to a fission weapon is – I think – more likely to destroy it before it can go off than to set it off, regardless of its design. In either case, the resulting contamination is disastrous. --Lambiam 08:55, 5 December 2021 (UTC)
 * BTW, the captain at the time of the incident was Nikolai Vladimirovich Zateyev. "Captain Alexei Vostrikov" is a pseudonym of Indiana Jones, an infamous archaeologist who claims to have made the Kessel Run in less than twelve parsecs – thereby establishing a lack of scientific credentials. --Lambiam 09:03, 5 December 2021 (UTC)
 * What I meant is a steam and/or hydrogen explosion in the reactor (like at Chernobyl) setting off the warheads. 2601:646:8A81:6070:E03D:3B7A:ECA5:DA02 (talk) 10:22, 5 December 2021 (UTC)

So where exactly DO we go one and all?
In a sailing vessel with a hybrid (both square and fore-and-aft) sail plan (such as a brigantine), if a white squall (or any other squall, for that matter) approaches from abeam without warning, which way should the helmsman turn her if her square sails are set -- upwind or downwind? How about if only the fore-and-aft sails are set? 2601:646:8A81:6070:E03D:3B7A:ECA5:DA02 (talk) 06:54, 5 December 2021 (UTC)


 * I think the general advice is to turn into the wind and confront any approaching high waves from the bow, but immediate reefing or even dropping the sails, especially those more to the fore, is also important to avoid the vessel capsizing or a mast breaking; the direction of the wind may vary abruptly during a squall. --Lambiam 08:25, 5 December 2021 (UTC)


 * Unlike the days of wooden ships, it is rarely feasible to send down steel topmasts and yards to reduce overpowering windage, nor to cut away a mast to relieve a ship on its beam ends. The master must rely on situational awareness of a thousand factors to avoid or find a way through mayhem... The practice in square-rigged ships encountering squalls is to bear away, ensuring that the load remains abaft the rig. Sheeting of fore-and-aft sails or the setting of an autopilot can frustrate this... From Sailing ships: a catalogue of disasters. Alansplodge (talk) 15:31, 5 December 2021 (UTC)


 * So, bear away = turn downwind? 69.181.91.208 (talk) 07:50, 6 December 2021 (UTC)
 * In this case, yes. ←Baseball Bugs What's up, Doc? carrots→ 10:31, 6 December 2021 (UTC)
 * Thanks! So, the guys who made the movie were right for once!  2601:646:8A81:6070:C5F1:8E3E:7A99:E108 (talk) 04:37, 7 December 2021 (UTC)

Land between two tributaries/rivers
Overall, the land drained by a river is called a drainage basin or watershed (or a bunch of other names listed there), but is there a more specific name for the localized space between two tributaries? For example, if a city was built at the place where two tributaries met, how would we describe its placement? It feels like there would be a name for that. When I search online for land between two rivers it leads me to Mesopotamia which is cool, but not really what I'm after. Matt Deres (talk) 15:27, 5 December 2021 (UTC)
 * The place where two rivers join is called the confluence. Cities built there are often described as "located at the confluence of the ___________ and _________." See: https://ludwig.guru/s/located+at+the+confluence --Khajidha (talk) 15:32, 5 December 2021 (UTC)
 * And our confluence article. Alansplodge (talk) 15:35, 5 December 2021 (UTC)
 * Aha! I knew there was a word; it just wouldn't come to mind. Thank you both! Matt Deres (talk) 16:30, 5 December 2021 (UTC)
 * But it's only part of what you asked for. Is there a word for the zone between two tributaries? --184.144.99.241 (talk) 22:27, 5 December 2021 (UTC)
 * I also want to know if there's a word for this except any combination of rivers, seas etc, not just tributaries. Sagittarian Milky Way (talk) 22:41, 5 December 2021 (UTC)
 * Tolkien invented the Elvish (Sindarin) word 'naith', as a translation of the common word 'gore', for such a feature.--Verbarson (talk) 14:31, 6 December 2021 (UTC)
 * According to our own article, the word for any such combination is the same: confluence. --Khajidha (talk) 14:45, 6 December 2021 (UTC)
 * A search for "confluence of the Mediterranean" seems to confirm that: https://www.google.com/search?q=%22confluence+of+the+mediterranian%22&client=firefox-b-1-d&sxsrf=AOaemvIYUEgZ1a5Yp-lc-zJVUcKWLuk0SA%3A1638801990167&ei=RiKuYcDFCd-NwbkPnISy8As&ved=0ahUKEwjAgOyTtc_0AhXfRjABHRyCDL4Q4dUDCA4&uact=5&oq=%22confluence+of+the+mediterranian%22&gs_lcp=Cgdnd3Mtd2l6EAMyBwghEAoQoAEyBwghEAoQqwIyBwghEAoQqwI6BwgjELACECdKBAhBGAFKBAhGGABQ0ARY3RpgyBxoAXAAeACAAdQBiAH7ApIBBTIuMC4xmAEAoAEBwAEB&sclient=gws-wiz --Khajidha (talk) 14:48, 6 December 2021 (UTC)


 * Sensu stricto, land between two rivers (or tributaries) almost never belongs to both, all land is in one river basin or the other. The boundary between river basins is called a drainage divide, and represents a putative boundary that separates all water that may flow into one river or the other.  Land that does not drain to the ocean is called an Endorheic basin, all other land belongs to a specific drainage basin, by which water reaches the ocean through a series of tributary basins.  -- Jayron 32 16:13, 6 December 2021 (UTC)
 * Mesopotamia (the part literally between the rivers) would technically be a peninsula (whether they have a confluence with each other or reach the Gulf without merging like in the past) but I don't think Mesopotamia if often called a peninsula. There's probably at least a thin strip of Mesopotamian farms outside the between the river area but the river would slow down invasions from Persia and Egypt so maybe that's why it was called Mesopotamia instead of Peripotamia. Sagittarian Milky Way (talk) 17:45, 6 December 2021 (UTC)
 * I know of literally zero people in the history of the world before you typed the above sentences that would consider Mesopotamia a peninsula. Please stop.  -- Jayron 32 13:20, 7 December 2021 (UTC)
 * Okay great, so no one considers the Tigris wide enough to cause a peninsula. I haven't heard it either. Sagittarian Milky Way (talk) 15:06, 7 December 2021 (UTC)
 * I doubt there will be a word for the zone between two tributaries - for example the distance from the Amazon's confluences with the Madeira (near Manaus) and the Tapajós (at Santarém) is about 400 miles.  Tributaries can enter from either side. 87.75.36.211 (talk) 12:02, 7 December 2021 (UTC)

Impact of tobacco toxins on plant itself
Cigarette says there are "many toxic chemicals in the natural tobacco leaf" that are already there before smoking. Why they don't harm or damage plant's own DNA? 212.180.235.46 (talk) 16:57, 5 December 2021 (UTC)
 * How do you know they don't? ←Baseball Bugs What's up, Doc? carrots→ 18:33, 5 December 2021 (UTC)


 * Many plants have toxic chemicals that act as insecticides and/or fungicides. Tobacco used to be (and still can be) used as an insecticide: -- 2603:6081:1C00:1187:C0D8:D7A:7996:A83B (talk) 20:48, 5 December 2021 (UTC)
 * Well, the DNA is contained in the nucleus, with the nuclear membrane forming the barrier. Just like the cell membrane, the nuclear membrane lets some things cross and keeps other things on one side of itself. The toxic chemicals may also be further segregated by being contained in their own membranes (think of the hydrogen peroxide in the lysosome). --Khajidha (talk) 14:50, 7 December 2021 (UTC)
 * "Toxic" does not necessarily mean "damages DNA" (genotoxic). "Toxic" is a polysemous word, and the core principle of toxicology is "the dose makes the poison". Nicotine itself, as mentioned, is very toxic to invertebrates, and is toxic to humans in sufficient doses—in fact it's been used in poisonings. I note that table a little ways down proceeds to list toxic compounds in cigarette smoke. Some of these are combustion products, not present in the tobacco leaf until burnt. And some of these are widespread in small quantities. Formaldehyde is produced by the body as an intermediate in amino acid catabolism. Acetaldehyde is produced in the liver by alcohol dehydrogenase metabolizing ethanol, which is present in small amounts in the blood even if you don't consume alcoholic beverages. But your body is adapted to the everyday amounts of these it's exposed to, and has mechanisms for detoxifying them. It's when exposed to much greater amounts that these mechanisms become overwhelmed and problems start. --47.155.96.47 (talk) 08:25, 10 December 2021 (UTC)

Would non-binary mammals be more efficient?
If everything had a wang and a womb and reluctance to being inseminated was the sexual minority instead of the other way around then the gene pool would be pregnant almost 24/7. Though if it were possible for that to be good enough to outcompete what we have now (?) and also to arise from random mutations in the first place (??) then sex may become more and more flatworm-like and evil over time with less of the gene pool pregnant at any given time. Sagittarian Milky Way (talk) 17:58, 5 December 2021 (UTC)
 * It would help if "efficient" was clarified for this context. However, there are reasons why flatworms do not rule the planet, or even fill all that many niches that other organisms haven't evolved to better fill. In terms of mammals doing this, I'd suggest that it would be inefficient from a resource perspective. Remember that any structures and organs within a given organism require both raw materials and energy (LOTS of energy) to produce, grow, and maintain. Let's just say that 50% of the time, half of those reproductive organs end up not being used during reproduction... that's an enormous waste of resources and energy. At least among chordates (as far as I am aware), hermaphroditism is very much the exception, not the rule, and usually only occurs under extreme stresses (such as an isolated population that almost entirely lacks one gender, and so needs to spontaneously get some of that gender or reproductive capability or die off). Additionally, what you are calling "reluctance to being inseminated" would be more properly called sexual selection, which is a tremendous driving force of natural selection and fitness of future generations. Given that, I doubt that removing sexual selection would be any more "efficient" at anything other than producing a ton of offspring, but those offspring have just lost benefit to one of the major factors in determining fitness. That's not very efficient, at least not in my book. Lastly, what do you mean by "evil" in this context? I have absolutely not idea. --OuroborosCobra (talk) 18:35, 5 December 2021 (UTC)
 * Perhaps the drawbacks of each organism having a half-system on each side would overwhelm the ability to outreproduce then. At least for "complex" or locomoting life. Well if everything was enough like the flatworms that make the news then Earth would be like a planet of sex predators and there may not be enough inter-individual cooperation for technology to ever get very high, though what does and doesn't seem evil is fuzzy and inconsistent within one human much less one culture. Spiders and parasitic wasps seem evil to me but flesh-eating bacteriums and Guinea worms don't have enough anthropomorphicizability-to-cruelty ratio. If I saw flatworms trying to stab each others' skin with their penes I wouldn't stomp them but if I saw a spider being as unoffensive as possible I stomp even though another will quickly take it's place but if it's too inconvenient I'm not bugged that bugs will be eaten alive for my convenience. Sagittarian Milky Way (talk) 22:05, 5 December 2021 (UTC)
 * "Anthropomorphicizability-to-cruelty ratio" - we really need this in subspeciesbox--Verbarson (talk) 14:23, 6 December 2021 (UTC)
 * Anthropomorphicizabilityxcrueltyy product or sum. Sagittarian Milky Way (talk) 19:42, 6 December 2021 (UTC)
 * Pregnancy is hardly free to the organism. In fact in humans lactation tends to suppress the menstrual cycle and therefore the ability to become pregnant—lactational amenorrhea—which implies some selection pressure, at least in humans, against the ability to be "constantly pregnant". The general question of why sexual reproduction is the norm for multicellular life, I thought, was called the "problem of sex", which shows up red, but you can read about the evolution of sexual reproduction. --47.155.96.47 (talk) 08:34, 10 December 2021 (UTC)

A tyrannosaurus by any other name
Ever since their discovery and modern interpretation, dinosaurs and other prehistoric animals have captured the popular imagination and, since they were not given "everyday" names, the public knows them solely by their genus names with one exception - the T. rex. Is there a specific (pun not intended) reason why it's the only prehistoric animal for which people know the species name? Or is it random happenstance? I'd wager almost nobody outside of paleontology could even hazard a guess of any other dino's species name, yet every 8-year-old in the world knows rex. I'd even wager that, outside of H. sapiens, Tyrannosaurus rex is likely the best-known species binomial, period. Is there a reason why? Matt Deres (talk) 20:49, 5 December 2021 (UTC)
 * Probably just happenstance. The meanings of the two parts of the binomial add up to "king of the tyrant lizards", and that has a sort of poetic feel that resonates, but it would not guarantee the widespread knowledge. Boa constrictor might be even more well known. Possibly even more well known than Homo sapiens, but most people may not realize that the "common name" there actually is the scientific name. --Khajidha (talk) 20:58, 5 December 2021 (UTC)
 * The Western gorilla is Gorilla gorilla, but that's not quite what you were asking about.--Khajidha (talk) 21:01, 5 December 2021 (UTC)
 * I'll see your Gorilla gorilla and raise you Bison bison bison. Card Zero  (talk) 02:37, 6 December 2021 (UTC)
 * There's also a gorillier gorilla (Gorilla gorilla gorilla). Of tribe gorillini. Sagittarian Milky Way (talk) 03:13, 6 December 2021 (UTC)
 * The expression E. coli is pretty well known, but the full genus-name Escherichia, not so much. --184.144.99.241 (talk) 22:30, 5 December 2021 (UTC)
 * Heck, I deal with cultures of E. coli at work, and still keep misspelling it as"Escherischia". --Khajidha (talk) 23:56, 5 December 2021 (UTC)
 * So did I when I first typed my comment. I was saved because no one's made that misspelling a link. --184.144.99.241 (talk) 04:22, 6 December 2021 (UTC)
 * C elegans is also well known to most people interested in science, though few of them could spell out its genus. {The poster formerly known as 87.81.230.195} 90.208.90.66 (talk) 10:43, 6 December 2021 (UTC)


 * This question reminds me of the "Did You Know" segment from the main page on April 1 2010. Recent_additions/2010/April
 * ApLundell (talk) 02:45, 6 December 2021 (UTC)
 * The single-syllable specific name makes it catchy and easy to remember. How many others are there? Crex crex, Lynx lynx. Not many. Card Zero  (talk) 03:14, 6 December 2021 (UTC)
 * Aha ha. Sagittarian Milky Way (talk) 03:23, 6 December 2021 (UTC)
 * Nice, and there's the list. That T.L. Erwin's taxonomy is out of control. Agra dax, Agra max, Agra nex, Agra nox... Card Zero  (talk) 03:40, 6 December 2021 (UTC)
 * This RefDesk thread from a year ago mentions some of the above as Latin binomials in common usage, but also boa constrictor and glis glis. Alansplodge (talk) 00:19, 7 December 2021 (UTC)
 * I'm not sure how old the use of the "T. rex" abbreviation is, but I wonder if its adoption was influenced by the popularity of T. Rex (band) in the 1970s? Alansplodge (talk) 13:49, 6 December 2021 (UTC)
 * www.etymonline.com agrees: Abbreviated name T. rex attested by 1970 (apparently first as the band name). Alansplodge (talk) 14:02, 6 December 2021 (UTC)
 * : "Tony Visconti (their producer for several albums) claimed in a documentary on the band that he had taken to using the abbreviated term "T. Rex" as a shorthand, something that initially irritated Bolan, who gradually came around to the idea and officially shortened the band's name to "T. Rex" at roughly the same time they started having big hits (shortly after going electric).]" The single "Ride a White Swan" was the first release credited to the abbreviated "T. Rex", in October 1970, released on the band's new Fly Records label.  Ghmyrtle (talk) 14:48, 6 December 2021 (UTC)
 * The band may have been where most people first encountered the abbreviation, but it was used in E. A. Maleev's 1955 paper on Tyrranosaurus bataar. As is usual in papers such as this, he used T. rex and T. bataar for the two species to save time. The band's choosing the shorter form was probably influenced by this standard practice in scientific writing. --Khajidha (talk) 14:55, 6 December 2021 (UTC)
 * I haven't been able to check H. F. Osborn's earliest paper on the animal, but his second communication to the American Museum of Natural History on the subject (1906) used the abbreviated form. This is absolutely standard practice when mentioning a binomial multiple times in one paper or when mentioning multiple species in the same genus. --Khajidha (talk) 18:08, 6 December 2021 (UTC)
 * Thank you for the insights, though the bit about T. Rex is maybe a secondary part of the question. As a fan of the group, it's awesome to think that they played a part in popularizing the short form. However, the basic part of my question is why the rex part became so widely known in the first place. Every eight year old kid in the world for the last century could tell you Stegosaurus, Triceratops, and Tyrannosaurus... rex. I guess it's a nice short name, but kids have little trouble with pronouncing Pachycephalosaurus. I guess what I'm getting at is: was there perhaps a very influential book or display that chose to include the T. species name but not others? Matt Deres (talk) 14:55, 11 December 2021 (UTC)