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February 24

Celestial bodies named after Greek mythology - c or k?

When the IAU names a celestial body after a figure from the Greek mythology - what does it depend on whether they use a spelling most truthful to the Greek original (namely with the letter k) or the Latinized spelling (namely with c) - see e.g. Eukelade vs. Carme (moon) ? --KnightMove (talk) 13:02, 24 February 2022 (UTC)[reply]

Not 100% sure, as Astronomical naming conventions does not specifically say, but in general, naming rights are generally granted as an honor to the first discoverer of something, AFAIK, that is both how IUPAC handles the naming of chemical elements and how ICZN handles the naming of animal species. According to the article you linked, Carme was named in 1938 by its discoverer for Carme, which appears to have been spelled with a C in English since before the moon was named. --Jayron 32 13:12, 24 February 2022 (UTC)[reply]

That makes sense... but still Eukelade was also discovered by a US team, and she is written with a c in English?! --KnightMove (talk) 13:24, 24 February 2022 (UTC)[reply]

Possibly because "ce" in English often makes an "s" sound. Lots of Greek names in English also maintain k in the spelling; Eukelade (the muse) is such a minor character I can't find much on her, but it isn't hard to find English using "k" in Greek mythological names, Keres, Nike, etc. --Jayron 32 13:33, 24 February 2022 (UTC)[reply]

Thank you very much! --KnightMove (talk) 15:23, 24 February 2022 (UTC)[reply]

The article Name conflicts with minor planets includes some examples where a moon and an asteroid only differ by this same c/k. For example, 53 Kalypso and Calypso (moon), 548 Kressida and Cressida (moon). --Amble (talk) 18:14, 24 February 2022 (UTC)[reply]

wp:deny

Not sure why the IP thinks the UK spelling is Chanucah. That gets no hits on the BBC news website whereas Hanukkah gets loads Mike Turnbull (talk) 17:45, 25 February 2022 (UTC)[reply]

I've just looked on the web page of the local synagogue and they spell it Chanukah! Martin of Sheffield (talk) 17:58, 25 February 2022 (UTC)[reply]

A hybrid version appears in Chanukah greetings from Mayor of London from The Jewish Chronicle (" the oldest continuously published Jewish newspaper in the world"), although the "kk" spelling does have a lot of hits on UK websites. Alansplodge (talk) 10:39, 26 February 2022 (UTC)[reply]

Thank you. I guess I need a more general follow-up question in the language section. --KnightMove (talk) 04:23, 27 February 2022 (UTC)[reply]

February 25

Bloch sphere

For some reason I had thought that the Bloch sphere was the infinite-dimensional complex Hilbert space that every wavefunction lives in, rather than just the two-dimensional one. Is there a physics term for the infinite dimensional one? Thanks. 2601:648:8202:350:0:0:0:C115 (talk) 20:27, 25 February 2022 (UTC)[reply]

No, but this is discussed on StackExchage/Physics here; and, have you seen the Hilbert space and related articles? --2603:6081:1C00:1187:1C8F:910:778:CC3A (talk) 22:24, 25 February 2022 (UTC)[reply]

Thanks, those were interesting but none addressed my specific question. Maybe there isn't such a term, which is ok too of course. 2601:648:8202:350:0:0:0:C115 (talk) 01:29, 28 February 2022 (UTC)[reply]

February 26

Ideal gasses

Can Maxwell's demon "cheat" the ideal gas law by pulling a piston a little each time it can do so without allowing atom(s) to bounce off the piston while the piston's moving? Presumably this isn't a real cheat either, any more than the one where the demon sorts molecules with a gate. If a microscopic piston could accelerate fast enough at a lucky time it seems like it could outrun all gas in the cylinder (is the easiest gas xenon?), expand it many times and return to zero speed before any gas particle caught up but I don't know if significant frictional heating or breakage from g-forces would happen in the real world. Sagittarian Milky Way (talk) 00:38, 26 February 2022 (UTC)[reply]

Note that for pressure P:

P={\frac {F\cdot {\text{distance}}}{A\cdot {\text{distance}}}}={\frac {\text{Work}}{\text{Volume}}}={\frac {\text{Energy (J)}}{{\text{Volume }}({\text{m}}^{3})}}.

For an ideal gas, the energy present in the gas is therefore given by PV which, when conserved, is a constant, Simply increasing the volume reduces its pressure. So the short answer is no, the ideal gas law isn't "cheated". --Modocc (talk) 02:43, 26 February 2022 (UTC)[reply]

I never understood how the gas particles were supposed to know to slow down (average speed), instead of just the joules per cubic meter decreasing. Since temperature is joules per particle. But when Comet Holmes had a sudden mass dump the gas sphere unsurprisingly expanded the same number of miles per day, no slowdown. Sagittarian Milky Way (talk) 06:46, 26 February 2022 (UTC)[reply]

Maxwell's demon doesn't cheat the ideal gas law, but it does cheat the second law of thermodynamics. As your piston moves out while no gas particles collide with it, the gas does no work on the piston and the gas doesn't cool down. The pressure drops inversely proportional to the volume. Why it doesn't work in the real world is always tricky with Maxwell's demon. For your second question, in a normal cilinder with a piston moving out, the gas particles know to slow down by the Doppler effect when bouncing against a moving piston: when bouncing off a moving target, the energy of the particle changes in the reference frame in which the target moves. PiusImpavidus (talk) 09:48, 26 February 2022 (UTC)[reply]

Yes I knew Maxwell's demon "cheated" a different thermodynamics law. So it is 100% the effect of the bounce surface moving away as I suspected but it seemed like a paradox cause presenting it as a law made me think was an uncheatable law of volume. What if you used a very skinny carbon nanotube as a cylinder to trap millions of xenons and you kept pulling the plunger till one time you got lucky and it expanded without any cooling? Could that work? Not sure if anyone tried, there might be nothing to learn. Sagittarian Milky Way (talk) 17:51, 26 February 2022 (UTC).[reply]

If there is no contact with the piston no work is being done by the piston, either on it or by it. Thus the xenon temperature and energy nRT remain constant and the density and pressure of the xenon gas become reduced as it expands into the larger volume. -Modocc (talk) 19:32, 26 February 2022 (UTC)[reply]

With such a piston the gas will expand or contract while preserving its temperature. So, the entropy change will be

\Delta S=nR\ln {\frac {V}{V_{0}}}

, which can either positive or negative. However I suppose that the total entropy of the system including the piston and the mechanism that moves it will have its entropy always increased. Ruslik_Zero 19:52, 26 February 2022 (UTC)[reply]

@Sagittarian Milky Way: Suppose you succeed to move the piston away so that the chamber length gets doubled whilst avoiding collisions during piston's moves. Then each gas particle needs to travel a doubled distance between collisions with the piston. As particles' velocities did not change, the frequency of collisions with the piston got halved. As a result the pressure dropped to a half of its initial value:

PV={\frac {P_{initial}}{2}}\cdot (2V_{initial})=P_{initial}V_{initial}=\mathrm {const.}

The law doesn't seem "cheated". --CiaPan (talk) 20:45, 26 February 2022 (UTC)[reply]

Usually both temperature and pressure drops but you can trick it so only pressure drops, that seems like cheating. You're right the usual effect on temperature of compression alone or expansion alone must have a different name. Sagittarian Milky Way (talk) 22:47, 26 February 2022 (UTC)[reply]

See https://en.wikipedia.org/wiki/Adiabatic_process#Adiabatic_heating_and_cooling It gives the different regimes: "The adiabatic compression of a gas causes a rise in temperature of the gas. Adiabatic expansion against pressure, or a spring, causes a drop in temperature. In contrast, free expansion is an isothermal process for an ideal gas." -Modocc (talk) 23:43, 26 February 2022 (UTC)[reply]

This is why I should've stayed in school, I never had high school physics, biology or the late part of chemistry year. Sagittarian Milky Way (talk) 00:24, 27 February 2022 (UTC)[reply]

See Joule expansion catslash (talk) 17:16, 27 February 2022 (UTC)[reply]

Interesting article, thank you. Sagittarian Milky Way (talk) 21:21, 27 February 2022 (UTC)[reply]

February 27

upper and downer drugs at the same time

I just read something about Anthony Eden taking Drinamyl, a combination of amphetamine and barbiturate. Why would those two drugs get combined, speed and a depressant? Do they cancel each other out? What was it used for? The article says it is discontinued now, probably for good reason. But I wonder what it was used for in the first place. 2601:648:8202:350:0:0:0:C115 (talk) 01:07, 27 February 2022 (UTC)[reply]

The Desbutal (a similar drug) article explains why this makes sense (or made sense back then) medically. The effect of combining substances is not algebraic, you are not combining 1 and -1. You can combine antagonizing substances to try to get rid of unwanted side-effects.

In both cases, Desbutal and Drinamyl, they were highly abused and are no longer manufactured.--Bumptump (talk) 01:42, 27 February 2022 (UTC)[reply]

Speedball (drug) has some discussion on this. Things that seem opposites don't necessarily cancel each other out; for example sugar and salt do not simply neutralize each other out in a dish. 85.76.97.34 (talk) 15:27, 27 February 2022 (UTC)[reply]

More legal Caffeinated alcoholic drinks also exist, i.e. espresso martini, formerly Four Loko etc. with a similar mix of a stimulant and a depressant. The Wikipedia article lists some reasons why people would consume them. --Jayron 32 13:00, 28 February 2022 (UTC)[reply]

They affect different parts of the central nervous system: dopamine release (amphetamine) and GABA receptors (barbiturate). Both drugs have wanted (pleasant) and unwanted effects (amphetamines: nervousness,... barbiturates: drowsiness, tiredness). They both lessen some of the unwanted effects of the other, without cancelling the wanted effects. Antipsychotics on the other hand block dopamine pathways, so combining them with amphetamines would make little sense, they would reduce or cancel all the effects. Prevalence 18:32, 3 March 2022 (UTC)[reply]

What's the proof that we can't see Far side of the Moon from Earth?

Moon is always white, spherical and spinning on its own axis, then what's the proof that we can't see Far side of the Moon from Earth? Rizosome (talk) 07:37, 27 February 2022 (UTC)[reply]

Well, the Moon has a landscape, with craters, mountains and large plains, it is neither perfectly white nor perfectly spherical. We always see the same landscape, the same side of the Moon (a bit more than half the Moon's entire surface due to libration) and noone had ever seen the other side before spacecraft went around the Moon starting in 1959. Is that proof enough? --Wrongfilter (talk) 08:12, 27 February 2022 (UTC)[reply]

Incidentally, "proof" is not quite the right term, "empirical fact" is better. --Wrongfilter (talk) 08:14, 27 February 2022 (UTC)[reply]

(edit conflict) What is the proof we can see the near side of the Moon from Earth? By definition, the far side of any object is the part you cannot see. If you accept that the Moon is far away from us and that the shape of its surface is basically a sphere, the two sides (the side that can be seen and the side that cannot be seen) are hemispheres. The point is that they remain (almost) stationary, so when we look at the moon we always see the same familiar features, the Mare Tranquillitatis, the Mare Fecunditatis, the crater Copernicus, and so on. What is the proof that we always see the same face? It has been obtained by observation. By looking up and seeing that the Moon looks just like yesterday, like last year, like on old paintings and like described by the ancients. Using telescopes astronomers can measure its speed of rotation very precisely, and it matches the speed with which the Moon circles the Earth. Since the latter varies somewhat in time while the two speeds keep matching, the only plausible explanation of this observed match is tidal locking. --Lambiam 08:15, 27 February 2022 (UTC)[reply]

The OP's question is rather silly on the face of it, unless by "proof" he actually means "explanation". --←Baseball Bugs ^{What's up, Doc?} carrots→ 09:02, 27 February 2022 (UTC)[reply]

What is the point of that comment? Do you have anything substantial to contribute to the question? --Wrongfilter (talk) 09:21, 27 February 2022 (UTC)[reply]

Thanks for the joke. I'm trying to establish what the OP is really asking. --←Baseball Bugs ^{What's up, Doc?} carrots→ 18:03, 27 February 2022 (UTC)[reply]

Possibly you wanted to ask some slightly different question, because the anwer for precisely this one is: there is no formal proof we can't (similarly to the lack of a proof man can't see the back of own head), but publicly available sources do not report on any such observations. --CiaPan (talk) 09:45, 27 February 2022 (UTC)[reply]

The moon is tidally locked as it orbits the earth, so we can see only one side of it. 2601:648:8202:350:0:0:0:C115 (talk) 10:10, 27 February 2022 (UTC)[reply]

The other way round: We can only see one side of the Moon, so we know that it is tidally locked. --Wrongfilter (talk) 16:33, 27 February 2022 (UTC)[reply]

Any proof will always be in terms of either postulates or what you're willing to accept without further examination. In this particular case, if you sketch out the system of a circle (you can project the system onto the plane) rotating around a point, then note that the circle is rotating around its own axis with the same angular velocity as its rotation around the point, it should not be difficult to demonstrate that the intersection of the line segment from the centre of the circle to the point with the circumferance of the circle does not change with time. — Preceding unsigned comment added by 37.165.69.92 (talk) 17:09, 27 February 2022 (UTC)[reply]

That is true if the Moon is tidally locked. But does it have to be locked? I think not – as long as the system is relatively undisturbed, yes, it's highly likely, but ultimately it depends on the history of the system. --Wrongfilter (talk) 17:14, 27 February 2022 (UTC)[reply]

Sketch out the system, then note that "the proof that we can't see the farside" requires that the two angular velocities be identical. Just why that might or might not be true (observation, predicted tidal locking or divine intervention) is a separate "question. 37.165.69.92 (talk) 17:43, 27 February 2022 (UTC)[reply]

It seems to me that there is nothing here that adds to the first two responses. --Lambiam 18:17, 27 February 2022 (UTC)[reply]

What's the "proof" that you can't see your own face except via a camera or a special arrangement of mirrors? -- Jack of Oz ^{[pleasantries]} 19:22, 27 February 2022 (UTC)[reply]

(on original topic) To me it was always just sufficient to note that it's not properly enough lit to see it. It can face the Earth, but we cannot see it. --Ouro (blah blah) 03:47, 28 February 2022 (UTC) No wait that's just not true! It doesn't really rotate. Stupid. --Ouro (blah blah) 03:48, 28 February 2022 (UTC)[reply]

It's worth noting that the Moon is not white. It's actually much closer to black, with an albedo similar to coal, but when it's lit by the Sun against the backdrop of space and viewed with dark adapted eyes it looks kind of pale. nagualdesign 03:58, 28 February 2022 (UTC)[reply]

Outside of solipsism, the proof that we can't see the far side of the moon from Earth is that we don't. It's an observation anyone with eyes can make. --Jayron 32 12:57, 28 February 2022 (UTC)[reply]

The first photographs of the dark side were taken in 1959 by the Russian spacecraft Luna 3, which enabled a map of the features to be made. The landscape is quite different from the features we can see from Earth. So we know what is there and we know that we can't see it. See also How the Soviet Union Snapped the First Picture of the Far Side of the Moon and What’s On The Far Side Of The Moon?. Alansplodge (talk) 14:37, 28 February 2022 (UTC)[reply]

This is true, but given the vagueness of the question, I took the OP's meaning to be "When we look at the moon in the sky, where is the proof that we don't see the other side." To which the answer is "You look at it, and you never see the other side". Perhaps the OP meant something quite different, but we all do the best we can given what we can interpret. --Jayron 32 15:47, 28 February 2022 (UTC)[reply]

There is no "dark side". Or rather, there are an infinite number of "dark sides". Far side. Far side. Not dark side. --jpgordon^{𝄢𝄆𝄐𝄇} 15:58, 28 February 2022 (UTC)[reply]

There is no dark side of the moon, as a matter of fact, it's all dark. --Jayron 32 17:02, 28 February 2022 (UTC)[reply]

From our article Far side of the Moon: ""The hemisphere is sometimes called the "dark side of the Moon", where "dark" means "unknown" instead of "lacking sunlight"". --Modocc (talk) 17:57, 28 February 2022 (UTC)[reply]

As with the old-fashioned expression, "Darkest Africa." --←Baseball Bugs ^{What's up, Doc?} carrots→ 19:50, 28 February 2022 (UTC)[reply]

Or less politically incorrect: the Dark Ages. Martin of Sheffield (talk) 21:10, 28 February 2022 (UTC)[reply]

Darkest Africa did not refer to the people. --←Baseball Bugs ^{What's up, Doc?} carrots→ 21:48, 28 February 2022 (UTC)[reply]

Unfortunately it was sometimes seen as a play on words, and really ought therefore to be avoided altogether today. Martin of Sheffield (talk) 22:56, 28 February 2022 (UTC)[reply]

I'm sure it could be seen that way. And it's obsolete. But it's another example of "dark" as "mysterious". --←Baseball Bugs ^{What's up, Doc?} carrots→ 02:28, 1 March 2022 (UTC)[reply]

It's worth pointing out that Rizo's initial question was, in fact, about the "far side" of the moon, not the "dark side"[1] --←Baseball Bugs ^{What's up, Doc?} carrots→ 06:14, 1 March 2022 (UTC)[reply]

While inside of a solipsist, it's too dark to read. Just like on the Moon. --47.155.96.47 (talk) 18:18, 28 February 2022 (UTC)[reply]

The Soviet Union had communication with Luna 3 between 4 and 22 October 1959. The far (as opposed to "dark" side of the moon ([2] at 2:49)) was fully illuminated by the sun at 12:30 GMT on 2 October. The sun moves across the sky thirty times slower than it does here. Photography began exactly 4 days 15 hours later and was completed within 40 minutes. 2A02:C7F:F206:A500:44D1:B021:3286:E546 (talk) 11:42, 1 March 2022 (UTC)[reply]

March 1

N.N.V.S.

There are some old astronomy references (c. 1930-1935) to a journal(?) about variable stars (or veränderlichen sternen) with the initials NNVS, but I can't find the full name. (Example: [3].) It's likely Russian or perhaps German. Contributing authors include P. Parenago, M. Zverev, and B. Kukarkin; probably of the Pulkovo and Tashkent Astronomical Observatories (later the Ulugh Beg Astronomical Institute). Does anybody have a hint about a full journal name? I didn't see them directly referenced in NASA ADS. Thank you. Praemonitus (talk) 00:26, 1 March 2022 (UTC)[reply]

In Google Scholar, I did the search "+nnvs abbreviations variable-stars". One of the first hits was History and Bibliography of the Light Variations of Variable Stars, appearing in a Harvard publication. It has a "List of Abbreviations" on pages 10-12, where NNVS is explained as "Verein von Freunden der Physik und Astronomie in Gorki (Nishni-Novgorod). Veränderliche Sterne. Forschungs- und Informationsbulletin." (I assume the last part is a description of the journal rather than part of the title.) --184.144.97.125 (talk) 06:10, 1 March 2022 (UTC)[reply]

Astronomical Series - The Flower Astronomical Observatory, Volumes 11-12 (1970) p. 348 confirms NNVS is Nishki Novgorod Veranderlichen Sterne. Alansplodge (talk) 12:39, 1 March 2022 (UTC)[reply]

They misspelled Nishni and used an inexplicably oblique (and de-umlauted) form of the adjective. The correct entry is NNVS Nishni Novgorod, Veränderliche Sterne.^[4] --Lambiam 15:20, 1 March 2022 (UTC)[reply]

Thank you. Praemonitus (talk) 14:34, 1 March 2022 (UTC)[reply]

I know proper names usually are not translated, but - just as a side comment - Nizhny Nov(y)Gorod is simply a Lower NewTown. :) CiaPan (talk) 13:37, 1 March 2022 (UTC)[reply]

Cf. History of Nizhny Novgorod. Praemonitus (talk) 14:45, 1 March 2022 (UTC)[reply]

You are probably looking for a journal published by Нижегородский кружок любителей физики и астрономии. AstroLynx (talk) 15:13, 1 March 2022 (UTC)[reply]

I found a biography about Boris Vasilyevich Kukarkin (1909-1977) that appears to cover the topic. Thanks. Praemonitus (talk) 15:23, 1 March 2022 (UTC)[reply]

March 2

Parrots picking people's teeth clean?

I just saw a Youtube video on my recommendations today and it reminded me about this. For some reason, pet parrots will sometimes stick their heads into their owners' mouths and pick the food from between their teeth. It seems to happen enough that if you google it, there are warnings about why letting them do this is a bad idea (human mouths are full of bacteria that can kill birds - same as cats, mainly) - and people do let them do it. I used to have a cockatiel that tried to do it with me, FWIW. Just got me thinking - is there some sort of wild behavior here that compels them to do this? Because voluntarily sticking one's head into the mouth of a carnivore seems like a fairly bad idea for anyone or anything. There are also several vids of parrots pulling out childrens' loose teeth (having being allowed to climb into their mouths), believe it or not. --Iloveparrots (talk) 00:01, 2 March 2022 (UTC)[reply]

Such behavior in parrots is likely a manifestation of their normal social grooming behavior that they exhibit towards members of their own species in the wild. This page here mentions that parrots in the wild groom other parrots. This grooming behavior is called "preening", and parrots will self-preen and also will preen other parrots (called "allopreening"). This page here describes the behavior as a form of bonding behavior, and birds in pair-bonds will preen eachother's beaks, for example. Apparently, parrots will do this with their human companions as well. --Jayron 32 00:12, 2 March 2022 (UTC)[reply]

That seems reasonable, though consider also this for a not mutually exclusive alternate hypothesis. Food is food, after all. Matt Deres (talk) 03:53, 2 March 2022 (UTC)[reply]

Are there any non-insane price globes with less relative error than cheap 12" Replogles?

Meridians misaligned by up to ~20 milliradians at the equatorial tape, even the number isn't consistent. The originally flat 30° gores are printed to more precision than can be squished onto a globe, leading to odd things like a line looking like _- at one part of a cut and another line looking like -_ at another part of the same cut. Are the globes that are somehow printed directly on ≥12" plastic balls better? Any other options? Sagittarian Milky Way (talk) 06:38, 2 March 2022 (UTC)[reply]

Are we really here to be your personal shopper? Presumably, you have access to things like Google and Amazon and are capable of finding products and reading reviews of them? --Jayron 32 11:57, 2 March 2022 (UTC)[reply]

I did Google it before asking and it is very hard to find this information. Just loads of pages that say a globe is more accurate than a map. And most globe users wouldn't care if the curvature is visibly irregular (like some globes, especially beach balls, which have crap printing too, the one I had as a kid) or the hemispheres or longitudinal strips don't line up by 2 millimeters on a 12 inch globe so there's always a chance a globe could be like this without one single review of it mentioning. Sagittarian Milky Way (talk) 14:39, 2 March 2022 (UTC)[reply]

Perhaps this review https://travelislife.org/who-makes-the-best-world-globes/ will help. Digging in to these, I spotted a misalignment even in one of the more expensive brands. So.. --Modocc (talk) 20:04, 2 March 2022 (UTC)[reply]

However there's a perfectionist who makes a living spending hundreds and hundreds of man-hours per globe going back and forth between looking at Google Satellite, Google Maps, geologic maps, elevation maps, air maps, star maps, sea maps, planet maps or anything else you want, painstakingly checking coordinates and painting what you want on a giant coordinates ball by hand. Some of the best globes ever made but costs more than some new cars. Sagittarian Milky Way (talk) 21:41, 2 March 2022 (UTC)[reply]

See You get what you pay for. --←Baseball Bugs ^{What's up, Doc?} carrots→ 23:22, 2 March 2022 (UTC)[reply]

I would recommend gemstone globes like this one. They may not be absolutely precise geographically but make up for that by their attractive design. I own several globes like this. Mike Turnbull (talk) 00:13, 3 March 2022 (UTC)[reply]

That's obviously a joke/trolling, considering that the OP is after precision. Bumptump (talk) 01:33, 3 March 2022 (UTC)[reply]

In principle, it is possible to bypass the gore details being squished and instead print directly on the globe, as on this night light globe. (The globe may even talk back to you.) It should be possible to attain a high precision this way, but I do not know if any globe manufacturers use such methods for making quality globes. --Lambiam 10:08, 3 March 2022 (UTC)[reply]

Billed as "The World’s Finest Globes", National Geographic is mid-priced and considered an academic standard (or is at least a common classroom fixture). 2603:6081:1C00:1187:3C7A:9601:8A34:9AA5 (talk) 19:20, 3 March 2022 (UTC) . . . Hmmm, their site states: We can't find products matching the selection.[reply]

March 3

Medical term for multiple diagnoses

What is the term when a hospital patient has multiple diagnoses or ailments, I have heard it before it is not "multi" or anything like that. I am having a brain hiccup here. Thanks in advance!2600:1702:690:F7A0:E8C4:93D8:8565:9D61 (talk) 03:49, 3 March 2022 (UTC)[reply]

Comorbid. Card Zero (talk) 03:52, 3 March 2022 (UTC)[reply]

A thousand thanks! It is strange what the brain just won't remember, much appreciation!2600:1702:690:F7A0:E8C4:93D8:8565:9D61 (talk) 05:05, 3 March 2022 (UTC)[reply]

And the corresponding noun is comorbidity, on which we have an article. --Lambiam 09:55, 3 March 2022 (UTC)[reply]

Sand shortage

In future, there will be no sand for construction?

https://www.dw.com/en/sand-crisis-shortage-supply-mafia/a-56714226

https://www.bbc.com/future/article/20191108-why-the-world-is-running-out-of-sand --Knight Skywalker (talk) 07:23, 3 March 2022 (UTC)[reply]

To a certain extent, sand that is usable as construction aggregate is a renewable resource, but it appears to be used up faster than it is being replenished. Much use of sand, in particular in making concrete, can be replaced by crushed stone, but (depending on the local circumstances) this may be more expensive. As sand gets scarcer and more expensive, the relative share of other forms of construction aggregate (including recycled aggregate from demolition and such, now often treated as waste) will increase. Also, more use can be made of wood and bricks in constructing buildings. So this does not have to be a yes-or-no thing. --Lambiam 09:50, 3 March 2022 (UTC)[reply]

Recycled sands are an environmentally friendly, cost effective alternative to natural dug sand. Sourced from crushed concrete, crushed glass or re-used sand, recycled sands are sustainable products that reduce waste to land-fill. [5] Alansplodge (talk) 18:07, 3 March 2022 (UTC)[reply]

How analog video signal converted to raster scan?

I understand this is how structure of analog video signal look like.

But how this structure converted to Raster scan? Rizosome (talk) 20:06, 3 March 2022 (UTC)[reply]