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April 17

Whitcomb rule for cars?

is the Porsche 911 GT1 designed according to Whitcomb rule? is it of any value at these speeds? thanks! --RM

The Whitcomb area rule, also called the transonic area rule, is a design technique used to reduce an aircraft's drag at transonic and supersonic speeds, particularly between Mach 0.75 and 1.2 (575 to 920 mph, 926 to 1482 kph), see Area rule. A Porsche 911 GT3 manages at most "only" 193 mph (311 km/h) and the GT1 is slower, so No and No. DroneB (talk) 01:18, 17 April 2020 (UTC)

Quiz question. One GT3 can manage Mach 0.25. How much can four GT3s manage?  --Lambiam 08:18, 17 April 2020 (UTC)

Quiz answer: by exchanging fuel they can send one car twice as far. Cars #1..4 set off in parallel. When cars #1 & #3 consume 50% fuel they stop and instantly (this part is magic) give their remaining fuel to cars #2 and #4 respectively. When cars #2 and #4 again have 50% fuel, car #2 stops and (magic again) gives its remaining fuel to car #4. Car #4 now has full fuel tank again and completes the trip. DroneB (talk) 15:39, 17 April 2020 (UTC)

Car #1 is driving on the roof of car #2, car #3 on the roof of car #2, and car #4 on the roof of car #3. Net result is car #4 much greater than Mach 0.25 in the frame of an observer outside the car-stack. Sadly even if we do this as plain vector addion, neglecting all aerodynamic, acceleration-distance, and wobbly-stack concerns, we can only get up to Mach 13.25, as the next Mach 0.25 increment is missing. DMacks (talk) 15:56, 17 April 2020 (UTC)

At User:DroneB's request, I have small'ed my US-centric ancient pop-culture humor. DMacks (talk) 02:24, 20 April 2020 (UTC)

Ooh! Ooh! ←Baseball Bugs carrots→ 02:51, 20 April 2020 (UTC)

Dare I say, the speed and aerodynamics of four cars driving near each other at high velocity are governed by difficult nonlinear equations? 16:14, 17 April 2020 (UTC)

The hell they do. DMacks (talk) 16:20, 17 April 2020 (UTC)

We have a Whitcomb area rule article. DMacks (talk) 14:51, 17 April 2020 (UTC)

thanks! --RM

What is the color of iron(II) selenate???

I'm don't sure that iron(II) selenate will have green colored (penta- and hepta- hydrate). So what is color of this compound??? (Sorry if you don't understand, because my English is not good).--Ccv2020 (talk) 09:55, 17 April 2020 (UTC)

It appears to be a compound without nearly any commercial application; indeed I can't find anything more than confirmation that it is possible to make it. There is not even an MSDS for it which is a dead giveaway that you literally can't buy it anywhere, which will put a crimp on finding pictures of it to check out the color. As such, it is super rare to find anything about it online; the Misplaced Pages article iron(II) selenate has only one non-print reference, but even that is a scan of a 1918 paper describing its synthesis. I can't find anything at all about it more recently than a few random papers that mention it from the mid 1990s. Your question may not be easily answerable from available information. --Jayron32 12:40, 17 April 2020 (UTC)

Could one estimate it computationally through ligand field theory? Yanping Nora Soong (talk) 14:59, 17 April 2020 (UTC)

Could one? Maybe. Has one? Probably not. --Jayron32 15:02, 17 April 2020 (UTC)

Tutton in the 1918 paper mentioned describes the mother liquor as green but the crystal were very hard to obtain, decomposing quickly with heat and air and he never seems to actually state the color of the crystal itself but notes the red and brown opaque contamination as they decompose. Green is most likely. Having worked on similar crystals, modern inert atmosphere techniques and vacuum systems as well as ice baths would seem to make the synthesis much simpler today but his story of waiting for a record cold snap in a severe winter to run the successful double salt reactions makes for an amusing story. Rmhermen (talk) 04:53, 18 April 2020 (UTC)

I agree green makes sense. Selenate probably adds little too the color, and iron (II) compounds are often a pale green in color.--Jayron32 18:00, 18 April 2020 (UTC)

Why do some scientists keep calling the Warburg effect and aerobic fermentation "inefficient"?

I've been a little confused by these two articles. We're covering these topics in grad school and almost all my lecturers take it as a given that aerobic glycolysis promotes accumulation of biomass (e.g. anabolism) rather than oxidation of carbon-carbon bonds to carbon dioxide (i.e. catabolism). I'm aware there are many nuances, including apoptosis and particular molecular targets or mediators, but overall, this seems like such an obvious driving force. Why do some scientists keep calling aerobic fermentation "inefficient"? Oxidative phosphorylation efficiently produces ATP, but it does not efficiently produce fatty acids to expand the lipid bilayer or new amino acids. Much of our assigned readings and reviews argue that in fact aerobic glycolysis is very efficient at incorporating biomass, just not that efficient at conserving ATP in times of starvation, emphasizing parallels between the "well-fed state" and the "starvation state" at both the systemic and cellular levels. Yanping Nora Soong (talk) 09:57, 17 April 2020 (UTC)

I think they're just alluding to the fact that aerobic respiration releases much more energy per molecule of substrate. At least for most animals I believe fatty acids and amino acids are obtained from the diet if possible; anabolic pathways are mainly used to convert one type into another as needed. De novo synthesis is done mainly to store excess nutrients or when needed in the fasting state, and essential nutrients can't be synthesized de novo at all. Not sure exactly how that goes in other organisms. I mean, I think you're right that calling it "inefficient" is probably an oversimplification. It sounds like people calling it that are thinking in terms of whole multicellular organisms rather than the cellular level.

Side note, but at least for most mammals, anabolism is linked to the well-fed state by insulin. When you're well-fed, high insulin levels promote uptake of nutrients and tissue repair and growth. --47.146.63.87 (talk) 22:54, 17 April 2020 (UTC)

Yes, but for T-cells, yeast and cancer cells alike, who are rapidly proliferating, glucose is a much faster way of obtaining biomass than capture of fatty acids AFAIK. Yanping Nora Soong (talk) 11:34, 20 April 2020 (UTC)

Yes, they're explicitly talking about the inefficient production of ATP per molecule of glucose. Honestly it strikes me as weird to talk about fermentation as being a better route toward biomass accumulation, since this necessarily ignores its last step, which leaves that carbon trapped in a toxic byproduct. And this can't explain the preference for fermentation when carbon is not a limiting factor to growth. But in that case, fermentation still has the advantage of being significantly faster in terms of atp production per unit biomass per unit time. That is, even though respiration generates 16 times the usable energy per glucose, fermentation is so much faster that it can overcome that. Though even that can't fully explain the preference. It's pretty complicated, not fully understood, and numerous models are still being debated. I'd point you to What is generally agreed on is that when a cell is uptaking glucose very quickly, the use of fermentation leads to faster accumulation of biomass, though does not require that fermentation is even the pathway through which the biomass is being accumulated. Someguy1221 (talk) 13:41, 18 April 2020 (UTC)

Proliferating T-cells show Warburg effect-like metabolism ... indeed, any proliferating cell. Does the sheer amount carbon of glucose end up in pyruvate? What about the pentose phosphate pathway? Yanping Nora Soong (talk) 11:34, 20 April 2020 (UTC)

Depends on the cell of course, but most of it leaves as lactate, with glutamine instead being used as a source of carbon for making new molecules. . A lot of microbes also prefer this arrangement. Someguy1221 (talk) 13:12, 21 April 2020 (UTC)

Scientific evidence of possibility of lab theories (Coronavirus)

Is there any scientific basis currently in the politicians claims that the SARS-COV2 could have been accidentally released from a lab? 90.198.251.144 (talk) 11:33, 17 April 2020 (UTC)

It depends on the politicians. ←Baseball Bugs carrots→ 12:06, 17 April 2020 (UTC)

No. it is a bullshit conspiracy theory. You should pay it no mind, and become highly suspicious of anyone who claims such nonsense as credible.. In the U.S., the main sources of the "theory" seem to be 1) Fox News 2) the New York Post (basically the print arm of Fox News) and 3) The Trump Administration, who started making public statements about it after Fox News began floating the idea (this is a standard pattern for statements by the Trump administration). In China, a similar theory is that it was created by the U.S. and released in China as a sort of bioweapon.. Both of these are bullshit theories. Nearly all actual reliable sources make it clear two things 1) we don't know much about it at all, and making definitive statements are hard and 2) what we do know seems to lean towards a zoonotic origin, likely a market in Wuhan. See for example. This is probably the best non-press summary about the current understanding. Scientists who are studying the disease most intently have a pretty clear consensus this is of natural origin. The "Made in a lab" bullshit is only coming from news organizations with sketchy reputations and non-scientific government officials with axes to grind. --Jayron32 12:53, 17 April 2020 (UTC)

It is not helpful to conflate "Made in a lab" conspiracy theories with the "naturally occurring virus accidentally released by lab which was studying it" question asked here. For the latter, see Misinformation related to the 2019–20 coronavirus pandemic#Accidental leakage. -- ToE 13:44, 17 April 2020 (UTC)

It's still a bullshit conspiracy theory. You'll note that you linked to the "misinformation" article. --Jayron32 15:01, 17 April 2020 (UTC)

I think it is incorrect to call it a "conspiracy theory" if the theory involves no conspiracies – except for the authorities not coming clean about it, which however is a ubiquitous phenomenon with people in power. Also, it is not impossible; the lab in question studies coronaviruses obtained from wildlife. Accidents happen, and the lab is situated close to the market. However, there is not a thread of non-circumstantial evidence, and specific allegations brought forward that seemingly support the theory appear, on closer inspection, to be made up or in any case incorrect. There is even no certainty that the wet market (or its close surroundings) were the source; it can have been a highly focal but secondary source.  --Lambiam 17:57, 17 April 2020 (UTC)

I agree, it's not a conspiracy theory. However, it's then a bit strange that the accidentally released virus happens to be such a massive problem for us now. If a lab collected coronaviruses from nature for study, then how did they end up with such a problematic virus for us? So, if it really happened this way, then the lab would likely have done experiments like e.g. mixing SARS with other viruses to see if a virus that is more infectious to humans than SARS could arise in nature. Count Iblis (talk) 19:37, 17 April 2020 (UTC)

"Naturally occurring virus accidentally released by lab which was studying it" would be easy to prove if that had happened. Scientific research, including at labs like that in Wuhan, is well documented. Early in working with a virus like this, they would have sequenced its genome (which, in fact, the Chinese did do early on in the outbreak, as there was no genome before the outbreak). That would be a very early step used then to classify any other results they made while studying this viral strain in comparison to other coronaviruses, such as SARS-CoV-1 and MERS. So... where's the documentation? All of the documentation out of Wuhan studying coronaviruses have different genomes than SARS-CoV-2, different enough that it clearly isn't a release from their lab. In my own lab, I could tell you the genome of the strains of infectious bacteria that I work with. I don't just know that I work with Staphylococcus aureus, but I know down to monoclonal strains, such as S. aureus Newman D2C NCTC 10833 or USA-300 strain of MRSA, etc. If the SARS-CoV-2 strain wasn't in their laboratory, they can't have accidentally released it. However, we HAVE found almost identical strains of coronavirus in bats and pangolins, which is why we think they are the likely zoonotic vector (most recently I have seen pangolins to bats to humans). There is a lot of piling evidence for the zoonotic vector, and zero evidence for an accidental lab release. It is still a conspiracy theory, as in order for it to be true, there would have to be a well organized conspiracy to suppress the evidence of a lab release. --OuroborosCobra (talk) 19:44, 17 April 2020 (UTC)

This. --Jayron32 20:09, 17 April 2020 (UTC)

Trump says it's plausible because "that bat wasn't in that area". Count Iblis (talk) 23:47, 17 April 2020 (UTC)

That is a really phenomenal example of an either-or fallacy. Someguy1221 (talk) 13:51, 18 April 2020 (UTC)

Conveniently ignoring the fact that bats fly and pangolins (also involved and the more likely final animal-to-human vector in this case) get moved around by people as part of the food and "traditional medicines" trades. {The poster formerly known as 87.81.230.195} 90.203.117.240 (talk) 03:30, 18 April 2020 (UTC)

If anyone is interested in shaping how our articles cover or don't cover this, they may want to participate in Talk:2019–20 coronavirus pandemic#Leaked from lab, in particular Talk:2019–20 coronavirus pandemic#Break. Nil Einne (talk) 11:39, 18 April 2020 (UTC) 02:55, 19 April 2020 (UTC)

Could presession (rosette-shaped orbits) be explained by gyroscopic effects, due to the orbiting body's spin?

Could presession (rosette-shaped orbits) be explained by gyroscopic effects, due to the orbiting body's spin?

Gyroscopic effects make it harder to change the direction of motion of a spinning object. Correct me if I'm wrong, but I believe this effect would affect the motion of a rotating body that's in an elipse-like orbit, more, when it's furthest from the object that it orbits, where gravity is much weaker, causing the far end of the eliptical orbit to be wider, thus causing presession.

What makes me think of this is the recent news report of confirmation of pressession of a star in an excentric orbit around our galaxy's supermassive black-hole. https://www.abc.net.au/news/2020-04-17/chile-astronomers-discover-star-dancing-einstein-theory/12158154

Secondarily, I'd like to know if it might also be because there's more drag closer to the black-hole due to electromagnetic forces or more dense dust-clouds.

I'm aware of possible relativity-based causes, of presession, however the exact mechanism by which this would cause presession has not been well explained in anything I've read thus-far. MathewMunro (talk) 14:18, 17 April 2020 (UTC)

I don't think so. As long as its mass can be considered equivalent to a mass concentrated in the orbiting body's centre of gravity – which is true if its diameter is small compared to its distance at periapsis from the host body – Newton’s laws govern the orbit (if the local spacetime geometry is flat). Gravity is the only force acting on the point mass.  --Lambiam 15:08, 17 April 2020 (UTC)

Lambian, do you believe that the orbit of a rapidly spinning object will be exactly the same as that of one that doesn't spin? I thought that the additional angular momentum of the rotation of a body around its axis would exert forces on its centre of gravity when it is in a gravitational field. Intuitively, if you try to turn an object like a rapidly spinning bicycle wheel, you notice that there are resistive forces that are not present when the wheel isn't rotating. MathewMunro (talk) 21:39, 17 April 2020 (UTC)

Gyroscopic effects make it harder to change the direction of the spin axis of a rapidly spinning object, but have no effect on the motion of the centre of mass. The spin frequency of an orbiting body can affect the apsidal precession (by creating a gravitational quadrupole moment as the object deforms and by relativistic frame dragging), but that's a very small effect and has nothing to do with gyroscopic effects. Read apsidal precession. Note that the general relativistic part of the apsidal precession in that article is not related to frame dragging. PiusImpavidus (talk) 09:15, 18 April 2020 (UTC)

"Gyroscopic effects make it harder to change the direction of the spin axis of a rapidly spinning object, but have no effect on the motion of the centre of mass." Thanks PiusImpavidus (and Lambian) for clearing up that misconception of mine. MathewMunro (talk) 20:58, 18 April 2020 (UTC)

"as the object deforms" - do you mean essentially tidal effects causing an exchange of angular momentum between the orbiting object and the body it orbits? MathewMunro (talk) 19:09, 18 April 2020 (UTC)

Not really. On the one hand there's tidal deformation of the planet orbiting a star (or a star orbiting a supermassive black hole). The tidal forces don't depend on the spin of the object, but the resulting deformation does. On the other hand there's the equatorial bulge of a spinning body. For symmetry reasons it must work both ways, but usually we can ignore the equatorial bulge of the secondary. With these deformations the body is no longer spherically symmetric and equivalent to a point mass, so apsidal precession will result. PiusImpavidus (talk) 09:58, 19 April 2020 (UTC)

Regarding the equatorial bulge of the central body due to spin, if an equatorial bulge were distributed equally on both sides of the line between the centres of mass of both objects, I don't think it would cause a deviation from elliptical motion. However, if the orbital plane & the central body's axis of rotation were oriented such that the equatorial bulge is sometimes off-centre, it would cause a deviation from elliptical motion, however such a bulge is not necessarily going to be offset by the same amount each time like a tidal-bulge is, so it wouldn't cause consistent apsidal precession. MathewMunro (talk) 13:07, 19 April 2020 (UTC)

Consider a spinning planet with its spin axis perpendicular to its orbital plane. The equatorial bulge moves mass from the poles to the equator. Some of this mass ends up at the terminator, sunset or sunrise. This is at the same distance from the star as the poles, so it doesn't affect gravity. Some of it ends up at the places where it's noon or midnight. This moves the mass towards the star or away from it, in the same way as tidal bulges do. The mass moving to the noon side cause a larger increase in gravity than the decrease coming from the mass going to the midnight side, and the effect is stronger when the planet is closer to the star. The effect does not rely on a misalignment between the axes of the ellipsoid of the planet and the line connecting the planet to the star. Redistributing the mass from a point at the centre of the planet to a spherically symmetric shell around it does not have this effect, as most of the surface area of the shell is further away from the star than the centre is, which exactly compensates for the larger increase in gravity for the parts that get closer to the star. PiusImpavidus (talk) 10:31, 20 April 2020 (UTC)

Thanks again PiusImpavidus. What would be the effect of equitorial bulge in the secondary on its orbit? I'm guessing that it would accelerate near the periapsis more than a non-rotating body would, which I'm guessing would swing it wide (negative aspidal presession), and increase eccentricity (although of course, other effects may dominate, and probably do, as most talk seems to be of positive rather than negative aspidal presession).

I'm also guessing that a body in an eliptical orbit, even a non-rotating one, would experience a torque for reasons similar to the ones you describe above (due to the side that is closer to the primary being pulled more strongly than the other side, and the net force being mis-aligned with the centre of mass of the secondary other than when it's travelling perpendicularly to the primary, at the apsis). I'm guessing that in the case of positive aspidal presession, due to asymmetry, there would be a net torque in one direction, I'm guessing it's in the counter-orbital spin direction. Your thoughts? MathewMunro (talk) 11:50, 21 April 2020 (UTC)

Also, since scientists are able to calculate the theoretical effect of spacetime curvature on the orbit very precisely (see Two-body problem in general relativity), the observed precession is adequately described by the theory (but perhaps not by anything you've read).  --Lambiam 15:20, 17 April 2020 (UTC)

Does the OP mean Apsidal precession, Axial precession, or Nodal precession? --Jayron32 15:14, 17 April 2020 (UTC)

The recently observed precession using the Very Large Telescope is reportedly apsidal.  --Lambiam 15:20, 17 April 2020 (UTC)

The star in question, S2, is at periapsis still 18 billion kilometres away from the black hole. For comparison, that is four times the distance of Neptune from the Sun. It is not plausible that dust clouds have a significant (observable) effect. If they did, causing the orbiting body to lose kinetic energy, the effect would not be precession but inward spiraling.  --Lambiam 15:30, 17 April 2020 (UTC)

Lambian, you wrote that "the effect would not be precession but inward spiraling", but might it be counterbalanced by a phenomenon known as "tidal despinning and orbital expansion", as described in this article: https://www.planetary.org/blogs/guest-blogs/2016/1017-rapidly-rotating-regular-satellites-and-tides.html (written by an orbital dynamicist and Associate Professor of Physics). "our own Moon is thought to have been mostly formed at a distance of ~3 Earth radii... Tides are then invoked to move it to its current position at ~60 Earth radii." MathewMunro (talk) 21:28, 17 April 2020 (UTC)

Lambian, there may be much more gas in the vicinity of the galactic centre than you think, even extending out to the range of S2's orbit. Refer to: https://www.mpg.de/8777573/gas-cloud-galactic-centre and https://www.sciencealert.com/strange-objects-have-been-found-orbiting-our-galaxy-s-supermassive-black-hole

The first article shows a picture of the massive gas clouds G1 & G2 whose orbit took them across the path of S2. The second article mentions that in passing close to the galactic centre, they shed outer layers of gas. It also refers to four other similar gas clouds, and suggests that binary star orbits may be destabilised by proximity to the supermassive black-hole, resulting in relatively frequent creation of gas clouds.

Another factor that might be relevant is solar-wind density being greater closer to the galactic centre. MathewMunro (talk) 00:57, 18 April 2020 (UTC)

Tidal locking is caused by a drag-like effect within the rotating body. It has nothing to do with drag caused by the interstellar medium. 93.136.29.149 (talk) 20:20, 18 April 2020 (UTC)

93.136.29.149, S2 would not be in tidal lock with the supermassive black hole. Tidal acceleration (or retardation) likely affects its orbit though. Tidal acceleration would speed-up an object in an eliptical orbit more at the periapsis than at the apoapsis, and if it's in a prograde orbit, that would cause retrograde apsidal presession (however S2 was observed to exhibit prograde apsidal presession), as well as making the orbit larger and more excentric, whereas a retrograde orbit, would have the opposite effect.

It's hard to know what the effect of interstellar medium would have higher average momentum in an outward direction due to sling-shot effects, imparting a net positive kinetic energy and gravitational potential energy to S2, or it may generally cause drag, and more so nearer the periapsis. It clumps and its density varies in a non-systematic way.

Accretion-disk radiation-pressure, would also be greater closer to the black-hole, by a factor greater than the square of the distance between the bodies, because the radiation is not only spreading-out in an inverse-squared way, but also being reduced in intensity as it climbs against gravity. It would also be offset from the black-hole's centre of mass to the approaching side of the accretion disk (presuming it's rotating as most are thought to), due to red or blue-shifting, which would contribute to apsidal presession, consistently.

And there's an inverse r to the sixth power involved in the tidal formulas. So these things may combine in a way that causes apsidal presession without noticable orbital expansion or contraction.

Without knowing the magnitude of all these things, I think it's jumping to conclusions to say that the apsidal presession of S2 proves General Relativity as the mass-media tends to. MathewMunro (talk) 10:57, 20 April 2020 (UTC)

I think we can safely say that electromagnetic effects are negligible. The accretion disk of the supermassive black hole in our Galaxy isn't particularly bright. PiusImpavidus (talk) 09:58, 19 April 2020 (UTC)

I don't know. The radiation pressure article says: "had the effects of the sun's radiation pressure on the spacecraft of the Viking program been ignored, the spacecraft would have missed Mars' orbit by about 15,000 km". Sagitarius A* has been described as "very bright" in radio frequencies. How does it compare to the sun for typical total electromagnetic energy output? MathewMunro (talk) 14:14, 19 April 2020 (UTC)

When I take the mass of the Viking probes and divide it by surface area pointing towards the Sun, I get about 200 kg/m. When I do this for star S2, I get about 5E11 kg/m. Radiation pressure acts on the surface turned towards the radiation source, gravity acts on the mass. So the effect of radiation pressure on the Viking probes, compared to gravity, was about 2.5 billion times stronger than on a star like S2 under the same circumstances. Add to this that Sgr A* is a particularly strong source of gravity (a few million times stronger than the sun). Sgr A* is a strong radio source, but there's little energy and momentum in radio waves. It's also a significant X-ray source, but that's relative: the entire Galaxy is quite dim in X-rays. In optical, you can't even see Sgr A* in images where you can see S2. PiusImpavidus (talk) 10:31, 20 April 2020 (UTC)

Thanks PiusImpavidus, nice. I wonder if the huge mass of Sgr A* would also make tides (and possibly even its own equatorial bulge) relatively less significant in a similar way? And is the mass of the accretion disk likely to be significant? MathewMunro (talk) 11:05, 20 April 2020 (UTC)

If you take a look through this user's contributions, they've come here before to push their pet physics "theory" that totally demolishes relativity. They appear to be here to just ask questions, not to learn. --47.146.63.87 (talk) 22:15, 17 April 2020 (UTC)

47.146.63.87 I deleted your irrelevant and rude contribution once already, as it was not worthy of a reply. Please kindly desist your disruptive editing. MathewMunro (talk) 01:03, 18 April 2020 (UTC)

April 18

Is sidereal month constant?

According to what I see here: "the time interval between two consecutive identical phases of the moon, for example, the time between consecutive new moons. The duration of the synodic month is not constant; the average length is 29.530588 mean solar days, and deviations range up to 13 hours". Is the duration of the synodic month is not constant because the the duration of the sidereal month isn't constant too, or the synodic month is the only one that isn't constant (while the the sidereal is)?

What's the reason for deviation of up to 13 hours in the synodic month?

What's the reason for deviation of up to 13 hours in the synodic month? and where I can find tables for this deviation in details with example of 12 months comparison? It's really interesting to see current examples. Thank you ThePupil (talk) 02:17, 18 April 2020 (UTC)

The sidereal month (also defined on the same site as your link in your previous query) varies with the time of year, because it's measured in relation to the background stars as seen from Earth, which drift around a full 360° over the course of one year (i.e. one orbit of the Earth around the Sun).

If the Earth's orbit around the Sun were circular, this drift would be constant, so the Sidereal month would be (close to) constant. However, the Earth's orbit is actually elliptical: the Earth is closest to the Sun in January and furthest away six months later, so it is moving fastest in January and slowest in July. Consequently the rate of drift of the background stars also varies, and in January (for example), the Moon has to travel a bit further to regain the same position with respect to them.

This is the main reason for the deviations, but there are other longer term variations in both the Moon's orbit around the Earth (see also Lunar theory) and the Earth's around the Sun, which also contribute small amounts.

In my experience, astronomers calculate the deviations using complex formulae when they need to rather than looking them up in tables, but its some decades since I was much involved in this stuff, so I don't know what current references might exist. {The poster formerly known as 87.81.230.195} 90.203.117.240 (talk) 03:20, 18 April 2020 (UTC)

charged particles emit virtual photons at each other? What wavelength/energy?

What kind of function of charge amounts and separation distance is it? Is an integer number of half wavelengths equal to the separation? Also what kind of wavelength/energy would be the photons between quarks inside of a proton?Rich (talk) 07:21, 18 April 2020 (UTC)

The interaction between quarks is mediated by gluons, not photons.  --Lambiam 08:12, 18 April 2020 (UTC)

They're charged particles - there will be an electrical interaction, even if it's not the dominant one. Someguy1221 (talk) 13:52, 18 April 2020 (UTC)

Elaboration: quarks have electric charge as well as color charge (associated with the strong interaction). They interact with each other electromagnetically, but when they are very close to each other, the strong force is much more powerful. --47.146.63.87 (talk) 22:36, 19 April 2020 (UTC)

Nothing is emitted. What is going on here is that a model that describes the true physical situation where the particles couple to photons cannot be treated exactly. We then consider a simplified model where the interaction between the particles and photons is zero, and we then perform an expansion around this zero interaction strength to get to a series expansion in powers of the interaction strength. what then happens is that the terms in this series expansion can be represented diagrammatically (Feynman diagrams) that look like physical processes where photons are emitted and absorbed. But these are not real physical processes. In these computations the so-called virtual photons can have energies and momenta that are not consistent with zero mass, they can have any mass, even an imaginary mass, because you have to integrate over the energies and momenta independently. Count Iblis (talk) 23:23, 18 April 2020 (UTC)

thanks!Rich (talk) 01:07, 19 April 2020 (UTC)

You might also find this helpful, again from Prof. Matt Strassler, written for a general audience. --47.146.63.87 (talk) 22:36, 19 April 2020 (UTC)

April 19

The definition of evolution in relation to humans

Evolution is simply whenever the genetic makeup of a particular population changes as a result of reproduction and, of course, the older generations gradually passing away, correct? The same also applies to human evolution, correct? As in, if a particular human group has its smart members reproduce much more than its not-so-smart members, then this group's genetic makeup is going to change over the generations (and it would also "help" with this that the older generations are gradually going to pass away) and thus this group is going to evolve to become smarter on average, correct? This would be an example of human evolution in action, correct?

All of this seems so obvious but I just want to make sure about all of this considering that I get the impression that some people even nowadays are oblivious as to the fact that humans are not immune from evolution even nowadays and that depending on which members of society reproduce more, humans even nowadays are capable of evolving in all sorts of different ways--whether becoming smarter, becoming duller, becoming thinner, becoming fatter, becoming stronger, becoming weaker, becoming taller, becoming shorter, becoming more liberal, becoming more conservative, et cetera. Of course, at least some of these factors could also be influenced by the environment, but nevertheless my point here is that even nowadays the genetic makeup of a particular human group/population could change through reproduction. thus causing this specific human group/population to evolve in some way. Futurist110 (talk) 06:58, 19 April 2020 (UTC)

See sickle cell trait and lactase persistence for examples of evolution in action in human populations in relatively recent times (last 10,000 years or so). Mikenorton (talk) 08:39, 19 April 2020 (UTC)

Yep, and another, much more controversial hypothesis is that Ashkenazi Jews evolved a higher average IQ over the last 1,200 years or so. If you'll take a look at this article, a 2005 paper actually proposed this as a hypothesis--as in, that there was selection for intelligence among Ashkenazi Jews during the Middle Ages and that smarter Ashkenazi Jews consistently out-reproduced duller Ashkenazi Jews for centuries during this time--thus causing the Ashkenazi Jewish average IQ to increase by ten or more IQ points from 800 AD to, say, 1800 AD or so. Futurist110 (talk) 18:32, 19 April 2020 (UTC)

Isolation of population groups is a factor in evolution. You can observe this in group traits and also in languages. ←Baseball Bugs carrots→ 10:47, 19 April 2020 (UTC)

Much of the change in the genetic make-up of Homo sapiens is due to random genetic drift, which is as often detrimental as it is beneficial, the separate minute changes being too small to result in an appreciable selective advantage. Natural selection operates as well, but its "natural" (often cruel) ways are nowadays often mitigated by medical intervention. Featuring a prediction of the long-term evolution of humankind used to be a staple item in pop-science magazines. Usually focussing on the phenotype, they described a future of hairless eggheads with formidable domes to accommodate their phenomenally large brains. For now, a breeding couple's being more educated tends to give more moderately sized litters, so I do not expect being smart to give much advantage until everyone can enjoy a good education. (Frankly speaking, I don't expect it will confer much of an advantage then either.) It only becomes really interesting if we have speciation, like the split into the Eloi and the Morlocks from The Time Machine. In other science fiction stories, space-faring humans have been depicted as having evolved to adapt to the weightless environment. If at some time genetic engineering applied to human embryos becomes socially acceptable (as it is in Brave New World), all bets are off.  --Lambiam 16:49, 19 April 2020 (UTC)

Human intelligence is a hugely polygenic trait which is also massively influenced by environment (nature versus nurture). You seem to be implying "smart parents have smart children", which is not really accurate. --47.146.63.87 (talk) 22:53, 19 April 2020 (UTC)

I tend to believe that the ability to score high on intelligence tests is not 100% an environmental matter, but that there is also a genetic component. I expect that children of very smart parents are, on average, at least a bit smarter than children of very not-smart parents. For evolution to work over very long periods, event slight heritable advantages suffice.  --Lambiam 00:37, 20 April 2020 (UTC)

There is also regression toward the mean to consider. This should also apply to IQ. So, on average, the children of extremely smart parents should be a bit duller than these parents themselves are. I've heard that regression occurs towards the family mean, but when we don't know what the family mean is, we should use the racial mean or ethnic mean instead assuming largely endogamous mating within this specific racial or ethnic group. For the children of mixed-race couples, of course, the regression should be towards the midway point between the means of the races of these children's parents. Futurist110 (talk) 00:57, 20 April 2020 (UTC)

Eugenics had been considered a legitimate scientific subject, but has become a taboo subject for scientists (for the obvious reason). There is, however, something known as New eugenics. 2606:A000:1126:28D:38A7:2D25:F9F0:4858 (talk) 19:05, 19 April 2020 (UTC)

I am actually personally a huge fan of (non-coercive) "new eugenics" just so long as everyone actually manages to have access to this technology--if necessary, through state/government subsidies for those people who cannot afford to use such technology out of their own pockets/checkbooks. Futurist110 (talk) 20:45, 19 April 2020 (UTC)

Do you consider elective abortion to be "non-coercive"? ←Baseball Bugs carrots→ 21:43, 19 April 2020 (UTC)

Yes, I do. Why? Futurist110 (talk) 00:47, 20 April 2020 (UTC)

Yes, biological evolution is just change over time in a population. Unless a species goes extinct, it's always evolving. There are lots of widespread misconceptions about evolution, often because it's not taught very well, and also in some cases due to misinformation spread by creationists. A lot of people wrongly conceptualize evolution as a process that has some kind of "final result" it's trying to achieve. And because we humans tend to think rather highly of ourselves, many assume humans are the "pinnacle" of evolution and humans are "done evolving"; this can be seen in the outmoded idea of a "great chain of being", which is often still implicitly popularized by the common visual metaphor of a linear progression of human ancestors leading up to modern humans. I like this Rationalwiki page which explores some of these misconceptions. --47.146.63.87 (talk) 22:53, 19 April 2020 (UTC)

I haven't looked at that RationalWiki page specifically and thus won't comment on it, but it's quite interesting how RationalWiki is attempting to smear anyone (such as Richard Haier, Noah Carl, Bo Winegard, and Nathan Cofnas) who argues in favor of an evolutionary explanation to observed human group differences on various important traits (such as intelligence)--or who is at least open to this possibility. RationalWiki denounces such views as "racist pseudoscience" yet it's fairly clear that with different selection pressures, different groups of humans could have indeed evolved differently on various important traits--including within relatively short time periods (such as centuries, in the possible case of Ashkenazi Jews) if the selection pressures on these traits were sufficiently strong. The SPLC is also guilty of being a bit too eager to dismiss such hypotheses (and, of course, to label such hypotheses "racist pseudoscience" or whatever--as if it's actually going to be the end of the world if these hypotheses will actually be proven to be true/correct!), in my honest opinion. In comparison to RationalWiki and the SPLC, people such as Steve Sailer really do appear to be voices, beacons, and paragons of reason in regards to this specific issue. Seriously. Futurist110 (talk) 00:50, 20 April 2020 (UTC)

Nah, the denunciation makes perfect sense. The type of people you're referring to aren't being flagged as racists for having controversial hypotheses - they're being flagged as racists for using uncertain science to argue for racist policies, and/or palling around with nazis (at least when the flagging is being done by those who have actually looked into the issue). The "I'm being persecuted for believing in SCIENCE" line is often a deflection from the real issue. Now, there is definitely a fear of stigmatization and knee-jerk reactions in this field, but that's due to how freaking many of the people publishing in it really are demonstrably racist.

Also, best to avoid ever saying you support eugenics. Simply because of who uses the term, it will for the foreseeable future be assumed to mean, "the coercive or forceful use of government power to prevent reproduction by individuals subjectively considered by those in power to be undesirable, usually on the basis of race, religion or national origin, but ostensibly in the interest of improving the average human condition." For comparison, even the most hardcore supporter of the death penalty would do well not to say something like, "let's do the holocaust, but for criminals."

I, for one, support the availability of genetic counseling and family planning, including voluntary abortion, provided on an individual level by one's own healthcare providers. I think parents should have the freedom to make decisions on the basis of genetics and the best science if so desired. I would never in a million years call this eugenics, because that word is used for racist ideas. Though if someone's idea of family planning is encouraging latinos not to procreate, it's not the word that's the problem. Someguy1221 (talk) 06:20, 20 April 2020 (UTC)

This is why there's a distinction between "positive eugenics" and "negative eugenics". I obviously support the former but not the latter. If terminology is a problem, though, then how about someone comes up with some better terminology for this? For instance, "population genetic improvement" or something even better? Personally, I like the term "positive eugenics", but if there's a better term for this, by all means, please present it!

As for advocating for racist policies, exactly which racist policies did people such as Richard Haier, Noah Carl, Bo Winegard, and Nathan Cofnas actually advocate? The only "racist policy" that I can think of in regards to Bo Winegard is that he apparently supports policies to slow down the rate of racial and ethnic demographic change in the US--or at the very least views the support of such policies (such as immigration restrictionism of some sort) as being a perfectly legitimate political position. (I deduced this information from looking at his Twitter feed.) Which other racist policies are any of these people advocating? By all means, please do tell!

As for palling around with undesirable people, this appears to be a guilt by association fallacy. The fact that someone pals around with, say, Communists does not in itself actually make this person a Communist. By this logic, maybe we should criticize, say, W. Kamau Bell for making conscious efforts to interact with the alt-right for his TV show, eh? Futurist110 (talk) 22:05, 20 April 2020 (UTC)

A new phase of human evolution may have started about 10,000 years ago due to invention of agriculture and the changes in the diet. Human remains from just after this transition show evidence of malnutrition due to eating one-sided diets. The original diet was a primarily whole food plant-based type supplemented by small amounts of meat and fish. So, we got all our protein from the plant-based sources and the small amounts of meat and fish made up for the compounds like vitamin B12 that are absent in the plant-based foods. After the invention of agriculture, we could get all our calories from more refined carbs and fats which are depleted n nutrients, particularly protein. We then had to get our protein from animal products, so we needed to eat much more meat and dairy. This was also necessary due to the lack of minerals like zinc and calcium from the new refined agricultural products.

Lactose intolerance which was the norm before agriculture, vanished in Northern Europe around this time. The driving force behind this was the high mortality of malnourished children due to diarrhea. If children could drink more milk, they would have a better chance to survive.

Polar bears are a good example of this, see here:

"But they are descended from terrestrial bears that, before colonising the frozen Arctic, ate a very different diet. “Their ancestors will have eaten healthy food like tubers and berries, and all of a sudden there they were eating almost exclusively fat and blubber from seals,” says Rasmus Nielsen of the University of California at Berkeley. “So the fast-food experiment has already been done by nature.”

To find out how the first polar bears coped with this dramatic shift in diet, Nielsen and his colleagues sequenced the genomes of 89 polar bears and 10 brown bears, their closest relative. Out of 20,000 genes, they found 20 gene variants that were most distinct in polar bears, and which evolution has evidently favoured."

The list of genes was dominated by metabolism, heart function and coat colour. “Usually, the genes that evolve most radically in species are immune and defence genes,” says Nielsen. “What’s surprising was the focus on cardiovascular function.”

Of the top 20 genes, nine relate to heart function or development in humans. One variant that scored especially highly was the APOB gene. This makes Apolipoprotein B (ApoB), the protein component of “bad cholesterol”, otherwise known as low-density lipoprotein (LDL). ApoB normally removes artery-clogging LDL from the bloodstream, dumping it out of harm’s way in fat cells or elsewhere." Count Iblis (talk) 01:43, 20 April 2020 (UTC)

I'd say you're right that nothing stops evolving, but it would be a mistake to assume that the existence of a selective pressure implies the population is evolving in the direction of that pressure. Not only are we often considering complicated and poorly understood genetic phenomena that are strongly influenced by environment (and that includes the behavior of other humans), we're talking about a population under many simultaneous pressures. It is my impression that "humans stopped evolving" is mostly an inaccurate executive summary of the vast selective pressures that have been minimized by modern medicine and other technology. Someguy1221 (talk) 06:26, 20 April 2020 (UTC)

I think the 47's point about creationists and misunderstandings of evolution is also important here. Some creationists like to spread nonsense like we've observed microevolution, but no macroevolution which they then argue doesn't exist which leads to the mistaken belief that evolution must mean radical changes. And outside of humans, there is also a lot of similar confusion, e.g. the belief that living fossils 'stopped evolving'. (When you combine the 2, you get a lot of weird confusion as the 47 sort of mentioned. E.g. questions over why monkeys or other primates "stopped evolving" or didn't evolve into humans.) Nil Einne (talk) 06:59, 20 April 2020 (UTC)

Virus Movie #2

• @Alansplodge:, @Lambian:, @Graeme Bartlett:, @DroneB:, @Graham Beards:
  

• I have re-recorded the video on the basis of your critique. I would appreciate if you can take 6 minutes time to view and add a brief evaluation. Thank you for your review.
• --Cookatoo.ergo.ZooM (talk) 17:37, 19 April 2020 (UTC)

after watching, it is now much less cluttered. Though you could popup some text when you mention a technical term, so that people know how the word is spelled. As regards accuracy I don't think is is quite correct to say that chains of amino acids polymerise into proteins. I should probably listen again to the exact wording, but amino acids polymerise into proteins (which are chains of amino acids). PS I am more into the chemistry side of Misplaced Pages. Graeme Bartlett (talk) 00:40, 21 April 2020 (UTC)

• Thanks, Graeme, for taking your time. I am planning better written textual information to improve didactics. I am currently using a standard video editor which is free as part of the OS but lacking in some useful advanced / professional / flexible tools.
• Good Day to Down Under. --Cookatoo.ergo.ZooM (talk) 20:16, 21 April 2020 (UTC)

Car air conditioning

Does the A/C in a 2017 Subaru Crosstrek draw in air from outside of the car? 67.253.78.55 (talk) 20:09, 19 April 2020 (UTC)

On page 250 of your owner's manual, the 'Air inlet selection' section explains that "On" position recirculates cabin air and "Off" draws outside air. 2606:A000:1126:28D:38A7:2D25:F9F0:4858 (talk) 20:28, 19 April 2020 (UTC)

High consequence infectious diseases (HCID) definition

According to the UK government, Covid 19 is not a "High Consequence Infectious Diseases" ].

The government website, and every other site I can find discussing or defining this only gives a qualatative definition:

• acute infectious disease
• typically has a high case-fatality rate
• may not have effective prophylaxis or treatment
• often difficult to recognise and detect rapidly
• ability to spread in the community and within healthcare settings
• requires an enhanced individual, population and system response to ensure it is managed effectively, efficiently and safely

Does anyone know (or know where to find) the quantitative definition of a HCID? (In particular, what fatality rate counts as "a high case-fatality rate"?) Iapetus (talk) 20:49, 19 April 2020 (UTC)

Googling the subject, it kind of seems like a judgment call. For example, Ebola virus disease has a high death rate, so presumably it would qualify. The UK originally labeled COVID-19 as HCID because they didn't know what the death rate was. It turns out to be relatively low, at least compared with Ebola. ←Baseball Bugs carrots→ 21:41, 19 April 2020 (UTC)

That's what I assumed was the reasoning, given that most of the listed examples seemed to be "any contact with an infected person and you will probably die" types of diseases. But it would be nice to have a harder definition - especially as I've seen people making various assumptions about the reason for the downgrade that either border on conspiracy theories ("the government is trying to cover up that it didn't take this seriously") or are out-right conspiracy theories ("Covid 19 isn't dangerous, the government is just using it as an excuse to impose a lockdown, for reasons").

Someone explained this to me a while back. HCID means that it is treated in special HCID centres. There are nowhere near enough of those to treat Covid 19 patients, so it is being treated in regular hospitals instead, out of necessity. Yes HCID is an escalated response, but what's happened with Covid19 is even more escalated, enough that HCID designation is wimpy by comparison. 2601:648:8202:96B0:E0CB:579B:1F5:84ED (talk) 02:34, 23 April 2020 (UTC)

April 20

Electric vehicles

If cars, buses, motorcycles become electric then will it affect the fossil fuel industry? -- 42.110.196.234

It depends on what gets burned to produce the electric power those vehicles will charge their batteries with. ←Baseball Bugs carrots→ 05:25, 20 April 2020 (UTC)

I was wondering about that. Given that large power stations are far more efficient at extracting energy than a small car or bus engine, could it be that, even if the power stations providing the electricity for those vehicles used the same petrol as the vehicles, we would need a lot less? But there is some loss when the electricity is transported into the battery, so it could cancel out, or be worse. Has anyone seen some calculation? --Lgriot (talk) 11:13, 20 April 2020 (UTC)

Yes, it will affect the fossil fuel industry. That's the whole point (in addition to reduced local emission of pollutants). Motorcycles and cars mostly run on oil-derived fuel (in particular petrol). Buses are more variable; around here they use compressed biogas, compressed natural gas, hydrogen fuel cells (they don't say how the hydrogen was made), electricity via batteries or overhead wires (they don't say where they buy the electricity) and sometimes still diesel. In any case, most road vehicles use oil-derived fuel, but fossil fuel power stations mostly use natural gas or (rapidly disappearing in Europe) coal, so at the very least there will be a shift away from oil. And a large fraction of our electricity, expected to increase, doesn't come from fossil fuels: hydropower, nuclear, solar, wind, ...

Given the efficiency of batteries and (to lesser extend) transport losses, battery-electric cars combined with oil burning power stations could very well give higher oil consumption than petrol powered cars (but don't forget the losses from converting crude oil to petrol). But that's irrelevant as there are (practically) no oil-fired power stations. The trick is to charge battery-electric vehicles when there's such a supply of wind or solar power that the price of electricity drops to zero (or less), which guarantees that they indeed charge from clean electricity. Of course, owners of solar panels or wind farms won't make a lot of money that way... PiusImpavidus (talk) 12:01, 20 April 2020 (UTC)

I think LNG is a good bet for fossil fuel future, it's cheaper than driving on both petrol and diesel and suitable for existing engines. A taxi company in my city started out with Priuses but when it decided to go bargain busting it swapped them all for petrol cars converted to LNG. Plenty of city buses use it too, although I think the majority are still diesel (and none are electric). 89.172.105.177 (talk) 00:39, 21 April 2020 (UTC)

Note that oil at least has many important uses beyond use as fuel (e.g. as a raw ingredient of plastics). So even a total switch to non-fossil fuel power sources wouldn't eliminate the oil extraction and refining industries. Iapetus (talk) 09:42, 21 April 2020 (UTC)

Renewable electricity overtakes fossil fuels in UK for first time (October 2019). Alansplodge (talk) 12:38, 21 April 2020 (UTC)

Let's hope there won't be a second time.  --Lambiam 19:57, 21 April 2020 (UTC)

Looks like the UK already imported almost half of it's energy by 2013 which The Guardian doesn't count (to Britain's carbon print). Wonder how much it's now.--TMCk (talk) 21:11, 21 April 2020 (UTC)

Penetration by particles

How exactly do beta and gamma particles penetrate human body? Do they slip through some microstructures or actually perforate, leaving microscopic holes like bullets on a larger scale? Thanks. 212.180.235.46 (talk) 11:11, 20 April 2020 (UTC)

They pass right through our atoms. PiusImpavidus (talk) 12:02, 20 April 2020 (UTC)

As shown by Ernest Rutherford in the famous experiment with metal foil. Under his direction Hans Geiger and Ernest Marsden fired alpha particles at various metal foils. The previous model of material was that mass was evenly distributed through space, so when they observed high-angle backscatter for a minority of the particles, this demonstrated that matter was instead concentrated in atomic nucleii. When Geiger reported back about the backscattered alpha particles, Rutherford said "It was almost as incredible as if you fired a 15-inch shell at a piece of tissue paper and it came back and hit you. " Mikenorton (talk) 13:38, 20 April 2020 (UTC)

So, to elaborate on this, the mental image of microstructures that particles can slip through is wrong. Think of marbles (representing the nuclei of the atoms of molecules) floating in space, practicing social distancing, where the recommended inter-marble distance is something like a half kilometre. Now you shoot at random into that largely empty space. Chances are that your bullet goes a long way before it hits a marble. Maybe it emerges at the other end without having hit anything. The molecular social distancing is the result of the van der Waals force, operating on the molecules substances are made up from. The same force keeps your feet from sinking into the floor as you stand: the molecules of your feet and those of the floor repel each other when approaching each other at a very short distance.  --Lambiam 15:59, 20 April 2020 (UTC)

The beta rays will disturb the electrons as they pass, perhaps ionising the atoms, or causing molecules to become excited, or to vibrate more. As suggested above, to actually make a hole you would actually have to hit or move a nucleus of an atom. For gamma rays, the photons do not punch a cylindrical hole, and only have an effect once they hit something and are absorbed and or scattered. You can expect disruption where they hit. Graeme Bartlett (talk) 00:34, 21 April 2020 (UTC)

Alpha particles colliding with nuclei can cause atoms to get displaced. It has been suggested that one can also search for dark matter this way by searching for tracks of atoms displaced by collisions with dark matter in certain minerals at some depth, see here. Count Iblis (talk) 03:31, 21 April 2020 (UTC)

Predatory Journals

Hi, while writing a draft on a Medical policy and saving it. I got a message saying some of citations might be “Predatory Journals”. I would like to know more about this particularly, wether any of my sources cited are in Blacklisted category. Where do I find more information on this? Regards Santoshdts (talk) 15:32, 20 April 2020 (UTC)

See WP:VANPRED. Mikenorton (talk) 15:43, 20 April 2020 (UTC)

What animal is this?

Is that a hippo? Or a warthog? It's from Central Africa (Gabon or neighboring territories), this is certain. Thank you! --Edelseider (talk) 16:21, 20 April 2020 (UTC)

Yes, it is a hippopotamus skull, as you can confirm here by comparing the two. In your picture, the top and bottom are not correctly aligned; the upper jaw is rotated clockwise (as viewed from looking over the top of it) relative to the lower jaw. --Jayron32 17:53, 20 April 2020 (UTC)

@Jayron32: Ah, okay, thank you very much! --Edelseider (talk) 20:18, 20 April 2020 (UTC)

What is this metal object?

I was walking in a forested area in south-east England and I found this metal disc thing embedded in the ground.

What is it?

Something used in forestry or agriculture? Thank you. --Polegåarden (talk) 21:24, 20 April 2020 (UTC)

• Unknown object
• Unknown object

I have no idea, but the second photo clearly doesn't seem to be the same object. What's up with that? --76.71.6.31 (talk) 23:45, 20 April 2020 (UTC)

I think they are the same. The first object isn't lying on the ground. It's sitting on top of the axle/post/metal rod(?) it's attached to. The second pic is a side-on view. But I have no idea what it is. HiLo48 (talk) 00:25, 21 April 2020 (UTC)

I agree that the in the first photo the disk may not be lying on the ground, although we were told that the thing is "embedded in the ground". But it is clearly circular and has a circular recess in the top, and a screw or bolt protruding at least 1/2 inch or 1 cm. The object in the second photo has four straight sides, no circular recess, and no protruding screw. So...? --76.71.6.31 (talk) 03:15, 21 April 2020 (UTC)

The second image is from directly side-on. We can't see anything about the top or the bottom surfaces, such as if there is a depression, or if there is a bolt in the depression that is not taller than the depression. Several of the other items visible on the ground in the two images match each other. Because I'm going stir-crazy from travel restrictions and needed a break from work-at-home, I annotated four such details (go to File:Unknown_object_in_rural_area.jpg and File:Unknown object in rural area 2.jpg in two adjacent windows, hover your mouse over each to see identified regions). DMacks (talk) 04:10, 21 April 2020 (UTC)

Oh, of course. Sorry about the distraction. --76.71.6.31 (talk) 18:05, 21 April 2020 (UTC)

I think it is a feeding station for gamebirds. Greglocock (talk) 00:29, 21 April 2020 (UTC)

That would have been my guess based on shape (or a mounting on which a feeder is bolted), but it seems too low (squirrels and other ground creatures could get up to it). DMacks (talk) 04:10, 21 April 2020 (UTC)

Thank you for your replies. Yes, the two photos are of the same thing. I've heard that it might be part of an old pheasent feeding station with some part missing. --Polegåarden (talk) 06:26, 21 April 2020 (UTC)

Something like this perhaps?. Alansplodge (talk) 12:34, 21 April 2020 (UTC)

Flu Vaccine Effectiveness

I've heard that all the flu vaccine does is decrease the time you have it, that does not stop you from getting it. Is this true? Pealarther (talk) 22:56, 20 April 2020 (UTC)

See Influenza vaccine. ←Baseball Bugs carrots→ 23:44, 20 April 2020 (UTC)

April 21

What is this common insect (Sweden)?

I have recently been observing a lot of these insects in my apartment in Linköping, Sweden:

• http://privat.rejbrand.se/insekt.jpg
• http://privat.rejbrand.se/insekt2.jpg
• http://privat.rejbrand.se/insekt3.jpg
• http://privat.rejbrand.se/insekt4.jpg
• http://privat.rejbrand.se/insekt5.jpg

The animal's body length is about one centimetre (0.4 inches). What kind of insect is it? --Andreas Rejbrand (talk) 10:26, 21 April 2020 (UTC)

A non-biting midge (Chironomidae)? Mikenorton (talk) 11:05, 21 April 2020 (UTC)

Agree, probably a male with those fluffy antennae, so not likely to bite. Richard Avery (talk) 13:28, 21 April 2020 (UTC)

Thank you very much! --Andreas Rejbrand (talk) 13:32, 21 April 2020 (UTC)

RNA to DNA conversion

In case of coronavirus diagnosis for example, why its RNA should be converted to DNA during real-time reverse transcription polymerase chain reaction, if it's seemingly more simple to search and detect its RNA directly? Thanks. 212.180.235.46 (talk) 19:25, 21 April 2020 (UTC)

I am not a PCR expert... that said, looking at our articles, I can see a possible explanation. Remember that all PCR techniques are dependent upon specific enzymes, such as DNA polymerase, working under the conditions of the PCR process. The polymerase is the thing actually copying DNA enough to be detected. Even when working just with DNA, not just any DNA polymerase can be used. You need one that is stable under thermal cycling, since the PCR process involves thermal cycling, and we thus use a very specific DNA polymerase (Taq polymerase, isolated from a thermophilic bateria). RNA-dependent RNA polymerase is not nearly as widespread among biological organisms as either DNA polymerase or RNA polymerase (which itself needs a DNA template to make RNA, and so wouldn't be useful in an application where you are starting from RNA). It's mainly found in viruses, and highly conserved among viruses, so there may not be a thermally stable version of it that could work for PCR application. Rather than trying to make out own (an incredibly difficult task), it is far easier to use a reverse transcriptase to make complementary DNA from the sample RNA material, and then use existing PCR techniques with DNA polymerase to amplify the material. --OuroborosCobra (talk) 20:06, 21 April 2020 (UTC)

It was once done directly by Northern blot but such a method was inefficient, not sensitive enough and prone to errors. Ruslik_Zero 20:40, 21 April 2020 (UTC)

But since the virus replicates, making more copies of itself, isn't the amount of RNA in the infected person sufficient for detecting and diagnosing directly, without the need for any polymerase? 212.180.235.46 (talk) 21:55, 21 April 2020 (UTC)

You are probably overestimating the amount of RNA that is recovered from a sample, and underestimating the amount of amplification your get from PCR. While it is possible to detect single molecules of RNA (for instance), doing that robustly, reproducibly, fast, and in a clinical setting is something different altogether. 30 cycles of PCR would theoretically increase the signal 2-fold, or over a billion times. Fgf10 (talk) 22:42, 21 April 2020 (UTC)

Almost all NAT tests require replication in order to have detectable amounts. Beyond that, the replication technique itself is a step in determining a positive detection. We don't merely "detect the presence RNA." You have tons of RNA in your body right now, your own RNA. You need to detect RNA of a specific sequence unique to the target organism. This is why PCR uses primer sequences, basically, a sequence of genetic material that is unique to your target organism, and highly conserved within it (not likely to change due to mutation). Genetic material matching that sequence is what is replicated and amplified. That means successful amplification not only gives you a measurable signal, but is also confirmation that the target organism or virus was in fact present in the sample. Otherwise, all RNA strands in a given sequence would need to be individually sequenced in order to determine their origin. In any human sample, you would have human RNA, you'd have symbiotic and commensal bacteria, etc. That's a LOT of sequencing to do. It is much simpler to have a primer that will only amplify the target organism or virus, and therefore will only work if the target organism or virus is present. --OuroborosCobra (talk) 15:15, 22 April 2020 (UTC)

Thanks. 212.180.235.46 (talk) 12:30, 23 April 2020 (UTC)

April 22

Unknown beetle

Does someone know what species this is? It was seen on the wall of a house on the Aegean coast of Turkey. It was about 25 mm (1 inch) long. Note the bands on the lower part going from side to side. Most beetles are smooth or have ridges in the length direction. I do not see a head. Thank you. Hevesli (talk) 09:05, 22 April 2020 (UTC)

Perhaps a juvenile cockroach nymph of some kind, but I have no idea which of the many types it might be. Mikenorton (talk) 10:32, 22 April 2020 (UTC)

Not so sure its a beetle which would generally have elytra or wing-cases which open from the centre line - I can't see that in that in in the photograph. Also dubious about there being a juvenile stage of any beetle; "Insects which undergo holometabolism pass through a larval stage, then enter an inactive state called pupa (called a "chrysalis" in butterfly species), and finally emerge as adults" (from Metamorphosis). Alansplodge (talk) 17:41, 22 April 2020 (UTC)

I'm not sure it's even an insect, though it certainly seems to have three pairs of legs. The segmented back makes me wonder if it's something like a woodlouse, or more generally some kind of isopod. AndrewWTaylor (talk) 18:18, 22 April 2020 (UTC)

I should have referred to cockroach nymphs rather than "juveniles". They are typically segmented, wingless and have heads that are not obvious from above, but I can't find any examples that match that picture. Mikenorton (talk) 22:35, 22 April 2020 (UTC)

Looks like it could be Polyphaga aegyptiaca in Corydiidae: see , . --Amble (talk) 22:40, 22 April 2020 (UTC)

Thank you. One from Malta has just the same markings on her back as the one I found and other details also look same. Hevesli (talk) 04:16, 23 April 2020 (UTC)

Apologies Mikenorton, you were on the right trail. Alansplodge (talk) 10:45, 23 April 2020 (UTC)

No problem, I must have looked at thousands of cockroach pictures, but failed to find the one that Amble spotted. Mikenorton (talk) 10:50, 23 April 2020 (UTC)

"God has an inordinate fondness for beetles". Alansplodge (talk) 16:26, 23 April 2020 (UTC)

Coronavirus responses

Would I be correct in assuming that almost all countries are simply following their national pandemic response plan in responding to the Coronavirus? 90.196.236.105 (talk) 10:00, 22 April 2020 (UTC)

The response should be tailored to the specific characteristics of the outbreak, so even under ideal circumstances it cannot be a matter of "simply" following a plan. Then, as should be apparent, political considerations play a considerable role in the appraisal of the situation and the appropriateness of specific responses, in some countries more than in others, but likely to a certain extent in all. On the face of it, it appears to me that the assumption is unwarranted.  --Lambiam 12:59, 22 April 2020 (UTC)

It might help if you mentioned what the alternative would be. To some degree, whatever each nation is doing now is according to "a plan". In some cases, "the plan" was hastily put together in March. Some nations have pandemic plans, likely written or updated in the light of SARS or H1N1, but it seems unlikely that those plans were complete in the sense that they likely didn't detail the degree of physical distancing we've done. A number of news pieces have commented that existing pandemic plans hadn't adequately prepared most nations for widespread infections, where sharing resources is not possible. Hence my request for clarification: having or not having a plan is not quite a black and white question. Matt Deres (talk) 13:36, 22 April 2020 (UTC)

April 23

Could Covid-19 have spread at multiple points from animals to humans?

If it is true that most of the early cases came from a single wildlife market, then one or more of the animals could have been infected prior to being shipped to the market. This would imply that the farmers or others handling the same animal(s) earlier could also have presumably been able to catch the virus.

So why are the earlier cases that were not linked directly to the market assumed to be evidence against zoonotic transmission at the market, rather than as evidence that there might have been an "animal super-spreader" of some kind, or simply that the same animal infected a handful of people handling it, and then was subsequently delivered to the market and spread the virus around at that market?

2600:8806:3400:3DB:793B:C7CF:650:5F5A (talk) 02:31, 23 April 2020 (UTC)Nightvid

My understanding is that the earlier cases and growing evidence against zoonotic transmission occurring at the meat market is because the genetic analysis indicates the possibility that the transfer occurred hundreds of miles away from Wuhan. I'm not sure what you mean by an "animal super-spreader." While it is possible that a single animal or group of animals transferred the virus to more than one person, I'm not sure that's relevant to the issue of the meat market. Basically, the genetic analysis shows 3 main subtypes, each splitting from the previous, i.e. subtype A is the root subtype emerging at or immediately after the zoonotic transfer. At some point, subtype B split off from subtype A, and then substype C split off from subtype B. The viral isolates from Wuhan are subtype B, which indicates that the zoonotic transfer event may not have occurred in Wuhan. Subtype A has been found in Guangdong province, which is 500 miles away from Wuhan, as well as in North America. What this seems to suggest is that the zoonotic transfer event could have happened earlier than we thought, and in southern China, and spread from there. At some point, subtype B mutated off of subtype A, and early on in its spread to Wuhan, mutated into subtype B, which dominated that outbreak. Independently, someone also carried subtype A to North America, which dominated the North American outbreak. Subtype C, at some point, mutated from subtype B, and is what was the type in the outbreak in Europe, as well as other areas of East Asia, but is otherwise largely absent from China.

So, it isn't just that earlier outbreaks occurred, and thus we don't think one animal could have caused both the earlier outbreaks and then the later one in Wuhan (and the wet meat market). Rather, the genetic analysis indicates that the outbreak in Wuhan was a product of human-to-human transmission already occurring, as it was a daughter type to that of the earlier zoonotic transfer event outside of Wuhan. --OuroborosCobra (talk) 02:50, 23 April 2020 (UTC)

Separate from your main point/reply to the question but this bioRxiv preprint suggests the subtype prevalent in New York is closer to the Italian one than the more common "endogenous" US one although they're relying on a marker to identify the subtypes Nil Einne (talk) 18:25, 23 April 2020 (UTC)

As we can read here: "The gene for the spike protein in SARS-CoV-2 has an insertion of 12 genetic letters: ccucggcgggca. This mutation may help the spikes bind tightly to human cells — a crucial step in its evolution from a virus that infected bats and other species." This means that before this mutation arose, there would have had to be infections with the virus with humans that then didn't cause an epidemic. The virus may not have been able to cause much of a disease in humans. But one can estimate what the probability of the insertion of the code "ccucggcgggca" and then deduce if this is so low that it would have had to happen in smaller steps. If so, then that would imply that virus was moving back and forth from the animal host to humans a long time before it had the capability of causing an epidemic in humans. Count Iblis (talk) 10:18, 24 April 2020 (UTC)

Cats vs. dogs cleanliness

I am looking for non-biased scientific information about the cleanliness of cats vs. dogs. I do not want any information from religious sources. For example, Islam does see cats as ritually cleaner than dogs. However, I want to find secular information about cats vs. dogs studied by scientists. Where can I find information about the cleanliness and diseases of these animals online? Thank you. WJetChao (talk) 09:39, 23 April 2020 (UTC)

Cat Cleanliness vs. Dogs. DroneB (talk) 11:01, 23 April 2020 (UTC)

• Cleanliness is not a scientific term, therefore your question cannot be answered using scientific sources, as you wanted. You'll have to define cleanliness. Fgf10 (talk) 12:35, 23 April 2020 (UTC)

  Can't we measure their respective distances to godliness?

  "Cleanliness" might not be a scientific term, but its a concept that could be defined in such a way that it could be scientifically investigated. I don't have any answers, but I don't think the question should be dismissed like that. Iapetus (talk) 08:45, 24 April 2020 (UTC)

There's no doubt it could be. But it hasn't been by the OP so far, so my statement about this particular question is completely correct. Fgf10 (talk) 15:09, 24 April 2020 (UTC)

• It doesn't take a rocket scientist to observe that cats tend to be more fastidious than dogs. That doesn't necessarily mean you want them walking on your dinner table, though. ←Baseball Bugs carrots→ 13:30, 23 April 2020 (UTC)
• Having had both cats and dogs, one very observable difference is that cats groom their coats, while dogs don't. Also, dogs like a playful rough-and-tumble with other dogs – which they make clear by inviting their playmates by vocalizing “rough! rough!”. This may get them pretty dirty. Adult cats may fight each other, but then it is not a play fight. If they have gotten dirty, most dogs will not mind getting a good wash, but many cats will resist vehemently. All this is strictly anecdotal and non-scientific. One could define a cleanliness measure by determining how much dirt can be collected from an animal's body, but how to define the population from which samples are taken? Should feral cats and dogs be included? Is it reasonable to compare dogs that go outside with cats that are kept indoors? And should the measure be absolute (in which case a St. Bernard will prove more dirty than a chihuahua) or relative to the animal‘s surface area? And are we really interested in just dirt? What about the shedding of hair? And so on. I doubt a scientist would undertake such a study in the face of such issues, unless there was an urgent need for an answer to some question – in which case the reason for the urgency would probably determine the operationalization of the concept.  --Lambiam 15:00, 23 April 2020 (UTC)

It has long intrigued me that we regard the cat behaviour of licking themselves all over as a sign of cleanliness. That wouldn't be the case if I did it. Probably more likely to be seen a sign of extreme weirdness and yuckiness. HiLo48 (talk) 18:53, 23 April 2020 (UTC)

We see it that way because it is actually part of their grooming/cleanliness practice, and if they don't do it, they don't get clean. Similarly, we wouldn't think of it as super clean to pick parasites out of each others hair, but certainly a lot of other primates would view that as part of keeping clean. For cats, part of why their tongue has evolved those backwards facing barbs is for the purpose of use in cleaning themselves. If you licked yourself that way, you don't have backwards barbs on your tongue, so you wouldn't effectively clean anything. --OuroborosCobra (talk) 18:57, 23 April 2020 (UTC)

CNBC reports air pollution drops by 180%

On April 23, an article on pollution during coronavirus situation said fine particle pollution in Manila went down by 180%. This might be an error. Or could it be theresult of calculating percent change as 100*(new amount-old amount)/(new amount), instead of 100*(new amt- old amount)/(old amt)? If that’s what it is, is this calculation standard, or becoming more common? Is it a more useful way to measure things?Rich (talk) 18:30, 23 April 2020 (UTC)

This teacher of Mathematics says it's utter nonsense. HiLo48 (talk) 18:36, 23 April 2020 (UTC)

Can you link to the article in question so we can look it over ourselves? --Jayron32 18:52, 23 April 2020 (UTC)

Here are two news articles giving the 180% figure: , . The last one references a press release by the Environmental Pollution Studies Laboratory of the Institute of Environmental Science & Meteorology at the University of the Philippines.  --Lambiam 19:15, 23 April 2020 (UTC)

Let's for a moment assume they did mean 100*(new amount-old amount)/(new amount). Let us calculate. Put for brevity x for the old amount and y for the new amount. Then we get

180      =   100 (y − x) / y

180 y   =   100 y − 100 x

  80 y   =             − 100 x

       y   =            − 1.25 x.

Negative air pollution! Probably from burning negative oil. This article reports a decrease from the typical Thursday peak value of 38 μg/m to 7.1 μg/m, which is a decrease by 81%. Probably, 180% was a typo for a rounded 80%.  --Lambiam 19:10, 23 April 2020 (UTC)

Yes but people typically will say there is a “50% off sale”, meaning the 50% is negative. So if -180%=100(y-x)/y, then -1.8=(y-x)/y, so -1.8y=y-x, so -2.8y=-x, so y=x/2.8. Since x was old amt and y is new amt that means if the old fine particulate was 38ug/m^3, then the new fine particulate is

amount is about 14ug/m^3, which i admit doesnt match the 7ug you found, but might have been correct on a different day.Rich (talk) 08:44, 24 April 2020 (UTC)

A quick review of the main page of www.cnbc.com (in the United States) shows this article: Photos show impact of temporary air pollution drops across the world from coronavirus lockdown. In that article, they make the more precisely-stated claim:

"In Philippines’ capital city, fine particulate matter — the world’s deadliest air pollutant — dropped by 180% since quarantine measures were imposed in Metro Manila on March 16, according to the Environmental Pollution Studies Laboratory of The Institute of Environmental Science and Meteorology."

With a little bit of follow-up, we can see the Environment and Pollution Studies Laboratory (the group who originated that "180%" number) are a research group in the Institute of Environmental Science and Meteorology at the University of the Philippines Diliman, the flagship campus of the University of the Philippines System and an organization of national repute.

I am still looking for the official source (e.g. a research paper, pre-print, or press-release) for the statement that CNBC is reporting.

Nimur (talk) 19:14, 23 April 2020 (UTC)

I assume when someone decided to publish those photos, they looked for something which sounded spectacular, but as the dates and ABS-CBN story shows, this is fairly "old news". Based on the ABS-CBN story linked above by Lambian ), the lack of any sign of this at , I guessed that social media may be where this originated.

Sure enough, scrolling through the history of this Facebook page @UPIESMEPSL, I found . That's actually just a comment of a Facebook post by @RCMakAirtoday. So I had a look at RCMakAirtoday and found this post of theirs on the ABS-CBN story, where someone questioned the 180%. In response, they pointed to this story where we find:

In calculating the percentage reduction, <name removed> said she got the difference between the value recorded during the enhanced community quarantine (ECQ) and the value two weeks before it was imposed.

“Then you divide the result by the value during the ECQ and and multiply it by 100,” she explained.

(20 less 7.1 results in a difference of 12. 19, which is then divided by 7.1. The result of 1.8 is then multiplied by 100, or a reduction by 181.6 percent)

Someone else responded questioning the 180% even with this explanation but there was no further followup. I don't know if there has been more discussion in other media outlets although I had a quick search and couldn't find anything.

BTW, whole looking into this, I found the figure is mentioned in 2020 Luzon enhanced community quarantine#Environmental. So if anyone is interested in getting into a debate over WP:CALC vs figures that are published in secondary sources, they could look into whether this needs to be changed. (Although you could just exclude any percentage figure.)

Nil Einne (talk) 06:54, 24 April 2020 (UTC)

They could mean that it decreased to an amount where it would have to increase by 180% to regain the original level. Sadly I see non-maths people mix that stuff up all the time even when they should know better. That would be 1/2.8 = 5/14 ~ 0.357 of the original amount (or a 64.3% decrease). Or maybe they mean it dropped by 80% (to 0.2 of the original amount) and the "1" is a typo. 89.172.105.179 (talk) 01:17, 24 April 2020 (UTC)

Perhaps the 180% is measured relative to an earlier and much lower-than-current baseline level, such as that in, say, 1950 (to take a random date). If the average level has tripled since 1950, then a 180% decrease would still leave it at 120% of the 1950 level. I stress this is just a conjecture, but it seems plausible to me that such a method might be used in some scientific context, though it would be a grave and confusing error to use the figure unexplained in a report destined for public consumption. {The poster formerly known as 87.81.230.195} 2.122.178.214 (talk) 06:25, 24 April 2020 (UTC)

If scientists worth their mettle measured a level, found it to be at 120% of a certain reference value and wanted to compare this new level with an earlier level at 300% of the same reference value by calculating the arithmetic difference of the two percentages, they would report a decrease by 180 percentage points. More likely though, if that reference value was so important that it is used as the yardstick, they'd give this unit a name, say PP₁₉₅₀, and report a decrease from 3.0 PP₁₉₅₀ to 1.2 PP₁₉₅₀.  --Lambiam 14:43, 24 April 2020 (UTC)

Deducing vegetation types

Hello. I am wondering if it is possible to deduce what kind of vegetation would exist in a given place that currently does not exist, for lack of habitat. I'm specifically referring to deducing what type of vegetation the Southern Hemisphere would have that would be analogous to the boreal forest/taiga and the temperate broadleaf deciduous forests of the Northern Hemisphere. If we look at a map of the world and maps of what kind vegetation types exist in different parts of the world, we can see that for the most part, all vegetation types that exist in the Northern Hemisphere have analogous types in the Southern Hemisphere as well. The specific flora may not be the same, but their adaptations, their form, their composition, will be very similar. This is true with two major exceptions, which I listed above.

So what I'm asking is, what would a Southern Hemisphere taiga and temperate deciduous forest look like? The reason that these ecosystems don't exist in the Southern Hemisphere is because of a lack of land at the right latitudes. So the north has extensive areas of taiga and deciduous forest because land exists for it in northern and eastern North America, in Russia, Siberia, Europe, and East Asia. No such land exists at the right latitudes in the south.

The reason I ask this is because I think it might be possible to deduce. The evergreen oaks of California have relatives in eastern North America that are evergreen and deciduous. The spruces, hemlocks, cedars, of the Pacific Northwest have relatives all over North America and Europe and Asia as well. So plants and trees of the same genus and families can certainly adapt to different climate types, as they have in the Northern Hemisphere. Can we make the same deduction that flora like Eucalyptus, Nothofagus, Podocarpus, can adapt to a humid continental climate and a subarctic climate like the Northern Hemisphere taiga and deciduous forests have? I know it's a stretch of the imagination, but I believe it might be possible. I just wonder if there are more educated views than mine on this topic. Thank you for your help.2600:1702:4000:5D40:C817:71F5:DF5A:F287 (talk) 19:22, 23 April 2020 (UTC)

Temperate deciduous forest exist in the Southern Hemisphere, it notes so in the lead section of that article. The closest Southern Hemisphere equivalent to taiga appears to be Magellanic subpolar forests, which aren't really taiga. As you note, there simply is no land in the Southern Hemisphere taiga belt, between the subpolar forests of Tierra del Fuego and the tundra of Antarctica is basically the Southern Ocean, where larch and spruce trees may find a wee bit hard to take hold. The closest to tiaga-like trees I can find in the southern hemisphere might be the Araucaria araucana, an alpine pine tree that grows in cold, dry areas of the Andes. --Jayron32 19:33, 23 April 2020 (UTC)

In the eucalyptus genus in Australia there is Eucalyptus pauciflora, commonly known as snow gum, thereby indicating where it grows. Rather than being at higher latitudes, it grows at higher altitudes, above 700 metres and up to a little over 2,000 metres (7,000 feet). It's known to survive temperatures down to −23 °C (−9 °F) and year-round frosts. It is, of course, evergreen, but can survive the loss of all its leaves and the death of all parts of the tree above ground (typically from fire) by re-sprouting from lignotubers. Given that there are over 700 species of eucalypt, and most seem to have evolved in quite recent geological times, the genus may well have been (and might still be) capable of creating a species to survive in even bleaker conditions, if such places existed. HiLo48 (talk) 00:07, 24 April 2020 (UTC)

April 24

Ocean swell or something else?

A question rather than an answer from me, for a change. In the photograph of the 150 km-long Antarctic Iceberg A-38 in this BBC article, I can see an apparent wave pattern whose wavelength must be on the order of 7 km. Our article on Ocean swell states "Occasionally, swells which are longer than 700 m occur as a result of the most severe storms." So, is this pattern ordinary ocean swell, but with a wavelength some 10 times the usual maximum, or is it a different (though presumably related) phenomenon, and is there a specific name for it? {The poster formerly known as 87.81.230.195} 2.122.178.214 (talk) 05:50, 24 April 2020 (UTC)

A natural sea wave with a 7km wavelength would be travelling at just under 400 km/h. So I don't think it is that. https://en.wikipedia.org/Wind_wave Greglocock (talk) 08:12, 24 April 2020 (UTC)

Maybe internal waves? PiusImpavidus (talk) 08:21, 24 April 2020 (UTC)

You mean in an interface (thermocline) between fresher Antarctic Surface Water and saltier Circumpolar Deep Water (as shown in the diagram here)? {The poster formerly known as 87.81.230.195} 2.122.178.214 (talk) 11:06, 24 April 2020 (UTC)

This article might be relevant: --Amble (talk) 15:58, 24 April 2020 (UTC)

Lutheria bi-beatricis

While browsing Special:Random just now, I encountered the Lutheria bi-beatricis article. I've never seen a scientific name with a hyphen before. (It's accurate; one reference is dead and the other doesn't mention it, but the authority-control at the bottom provides confirmatory links.) Does the existence of a species under this name preclude the future use of "Lutheria bibeatricis", or could a newly discovered species be given this name? Normally I'd create the latter title as a redirect, since absence of punctuation is a good reason for a redirect, but maybe this wouldn't be a good idea if a separate species could exist under this name. Nyttend (talk) 08:33, 24 April 2020 (UTC)

The use of hyphens by those following the current Shenzhen Code of the International Code of Nomenclature for algae, fungi, and plants is described here in Article 60 and here in Article 60. (Although I don't believe it's changed for a while, see e.g. the St Louis code Article 60 and Article 23.) As for a species without a hyphen but otherwise the same name, Article 53 may come into play. Nil Einne (talk) 11:02, 24 April 2020 (UTC)

Color of some cobalt compounds

Cobalt(III)...

• ...chlorate: I think it unstable. But what is the color of this compound? Thanks for much.
• ...perchlorate: I heard that it's only exists in solution. What is the color of this compound in solution? Thanks for much.
• ...bromide: I heard that it never been prepared. Can you are the first person prepare this? Thanks for much.
• ...iodide: also like bromide.

Cobalt(III) can oxidise water in acidic conditions. However it is quite common in complexes. eg hexammine or trisbipyridyl . Do you care about complexed cobalt for your chlorate and perchlorates? Graeme Bartlett (talk) 11:38, 24 April 2020 (UTC)

See also Bromopentaamminecobalt(III) bromide Graeme Bartlett (talk) 12:11, 24 April 2020 (UTC)

Complex ions have very different colors than naked ions. Also, for the most part (with some exceptions I'm sure), the color of any ionic compound of a transition metal ion is usually predominantly due to the complex ion itself. For example, many copper (II) compounds are generally green (anhydrous) or blue (hydrated crystals). The Cu(H₂O)₆ ion is a brilliant deep blue color, and the hydrated crystals of things like copper (II) nitrate and copper (II) sulfate and copper (II) chloride are generally a similar blue color. That being said, the chemistry of transition metal ion complexes is messy, and depending on the exact ion complex formed, you can get vastly different colors. This thread for example contains images of two different isomers of Hexamminecobalt(III) chloride, one of which is orange, and one of which is burgundy. The moral of the story is that for MANY transition metal ionic compounds, for various reasons owing to the electron energy levels in those d-orbitals, they tend to usually be brightly colored; however predicting the color of any one of them without actually synthesizing it and looking at it is folly; likely because there is really very little energy difference across the whole visible spectrum, and tiny little differences in electron energy levels caused by whatever the particular environment around a particular transition metal ion can cause a big shift in color. Also, with regard to many of these putative compounds you are asking about, just because you can write a formula for it doesn't mean it can exist. Many of these may be so unstable that it isn't possible to observe them to any degree of reliability. --Jayron32 14:18, 24 April 2020 (UTC)

Cobalt(IV)...

• ...fluoride: I heard that it's unstable gas. What is the color of this compound? Thanks for much. (This is more info, it maybe help you):

1. At -80 °C, Cs₂CoF₆ make a dark red solution in water.
2. At room temperature, Cs₂CoF₆ have gold-colored solid.

One more time, thanks for very much. (Sorry if you don't understand, because my English is not good).--Ccv2020 (talk) 09:50, 24 April 2020 (UTC)

That fluoride CoF₄ is formed at around 630K, but is only about 10 atmospheres in pressure. So it would not be a gas under standard conditions. The researchers studying this only observed infrared lines, and did not mention any optical spectrum or colour. The instability may be due to reaction with water breaking it up. Graeme Bartlett (talk) 11:52, 24 April 2020 (UTC)

Medical Advice Needed

Donald Trump says that disinfectant knocks Coronavirus out in one minute, and that it "does a tremendous number on the lungs". But I just realized, if I swallow the disinfectant, it will end up in my stomach, not my lungs. What's a good way to get bleach or isopropanol into my lungs? —Steve Summit (talk) 16:04, 24 April 2020 (UTC)

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