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August 27

Why do snails come out when it's raining?

I'd guess it's because they evolved from marine molluscs, and they would lose too much water under the sun, another possibility is that there's less predators in the rain. --TZubiri (talk) 03:05, 27 August 2020 (UTC)

Some species of snail cannot breath underwater. manya (talk) 04:21, 27 August 2020 (UTC)

The Land snail article states that they lay eggs, by digging into soil when it is moist. It would be easier to dig into moist soil, versus dry soilTribe of Tiger ^{Let's Purrfect!} 04:51, 27 August 2020 (UTC)

This page, although an enthusiast's website (rather than a scientific study), has a bit of info about snail dormancy during dry conditions. Our article on aestivation also covers this behaviour. PaleCloudedWhite (talk) 07:08, 27 August 2020 (UTC)

What's a top of the field cite count or h-index for a climatologist who's 36, 46, 56 and 66 years old?

Sagittarian Milky Way (talk) 04:28, 27 August 2020 (UTC)

Is there a documentation for pegion brood house sparrow?

Is there a documentation for pigeon brood house sparrow or vice versa - in nature? --ThePupil (talk) 12:11, 27 August 2020 (UTC)

Are you asking whether pigeons have ever brooded house sparrows (or vice versa) in the manner of, say, cuckoos and their infamous brood parasitism? They're not mentioned at List of brood parasitic passerines, though that list is obviously terribly incomplete. Some basic googling didn't turn up much. If you're asking whether it's possible to do, from the POV of raising orphaned chicks, it likely is with human intervention. I'm just basing that on how successful brood parasitism generally is, though. Matt Deres (talk) 19:44, 27 August 2020 (UTC)

Thank you. Basically I forgot to add two important words: in nature. I'm not necessarily talking about brood parasite which is usually refer to those who do it as a method. But I thought maybe it's possible to see a pigeon broods house sparrow eggs (not because the house sparrow is lazy like cuckoos, but because the pigeon found it without its parents for example). --ThePupil (talk) 05:40, 28 August 2020 (UTC)

It's impossible. Pigeons nest on cliffs and buildings and wouldn't even be able to access a sparrow's nest, which are generally hidden in trees or under eaves. Even if it chanced upon a sparrow chick it would have no interest in it. Even if someone put a sparrow's egg in with a pigeon it would probably just throw it out.--Shantavira|^{feed me} 07:41, 28 August 2020 (UTC)

Feral pigeons and their wild progenitors nest on cliffs and buildings, but that is not true of all other species of pigeon (e.g. Common wood pigeon). Whether a pigeon would incubate a sparrow's egg deposited in its nest by a sparrow or a human is a testable empirical question; I don't think it is helpful just to state your expectation about the outcome without evidence. As the cuckoo demonstrates, birds can be surprisingly "dumb" about rejecting eggs that look to us obviously not theirs. You will find lots of internet hits for eggs of geese and other domesticated birds being successfully brooded under hens. This summary lists studies where scientist-introduced eggs were even reared to fledging by other species in the wild. But these involved much more closely related species than sparrows and pigeons; pigeons feed their chicks a "milk" from their crop, not the diet that young sparrows need. Jmchutchinson (talk) 19:59, 28 August 2020 (UTC)

Thank you @Jmchutchinson. It seems it's more likely to see streptopelia broods pigeons eggs (or vice versa). Is there evidence for this thing? --ThePupil (talk) 09:58, 30 August 2020 (UTC)

It works in captivity. Here's a quote from [1]. "There are some species such as the Bleeding-heart Pigeon, that are difficult to breed or may abandon their eggs or hatchlings. In this case you can often successfully foster the eggs or young to other birds that are not so particular about breeding and are good parents. This can work if the eggs or hatchlings are within 4 or 5 days of the foster parents own. You must also be sure they eat a similar diet and that they are similar in size. Some very good foster parents include the Barbary Dove, Diamond Dove, Senegal Dove, Spotted Dove and some of the fancy pigeons."

In the wild, many species of birds, including some pigeons and doves [2] "egg dump", which means occasionally laying eggs in the nest of another pair. Usually this is intraspecific, but it does not seem completely implausible that very occasionally a mother makes a mistake and dumps an egg in the nest of the wrong species. Jmchutchinson (talk) 12:36, 30 August 2020 (UTC)

August 28

Large and small moons

I was fascinated to find out through our Main page today, that the asteroid 243 Ida has its own tiny moon.

What are the largest and smallest moons currently known to science? --Dweller (talk) Become old fashioned! 08:34, 28 August 2020 (UTC)

In our solar system, the largest known moon is Ganymede, and the smallest currently listed as a moon is S/2009 S 1. You could make an argument every grain of dust orbiting a planet is a moon though. Some potentially larger moons may be found outside our solar system. Fgf10 (talk) 08:47, 28 August 2020 (UTC)

I believe Titan is larger if astronaut eyeball opaque air layers count, Ganymede if only solids and liquids count. Sagittarian Milky Way (talk) 13:39, 28 August 2020 (UTC)

• (edit conflict) Natural satellite#Definition of a moon may get in the way of a definitive answer (as hinted in the answer above by the "grain of dust" argument). Tigraan^{Click here to contact me} 08:51, 28 August 2020 (UTC)

If you want the largest moon relative to its primary, the smaller component of 90 Antiope is a candidate. —Tamfang (talk) 01:04, 29 August 2020 (UTC)

Interesting stuff, thanks. My non-scientific perception is that science is so precise with its definitions of everything, so it's quite fun to find there's no precision here. --Dweller (talk) Become old fashioned! 09:24, 28 August 2020 (UTC)

Wow. Did you ever misunderstand "science". --Jayron32 09:37, 28 August 2020 (UTC)

Lol. I've persistently misunderstood it. Just ask any of my science teachers from my school days. --Dweller (talk) Become old fashioned! 11:30, 28 August 2020 (UTC)

It's part of the problem with our education system. There's two things that get meant by "science", and in schools we're really only taught one. The first is a list of "facts" (scare quotes intentional) that we're taught to memorize about things like biology and chemistry and geology and stuff. "Dmitri Mendeleev invented the periodic table" "The mitochondria is the powerhouse of the cell". Shit like that. An endless series of trivia questions for which we can repeat the answers of; as a small point we do sorta need to know these things, because understanding how the world works is of course the goal of science. But this is BY FAR the less important aspect of science. The more important aspect of science is the PROCESS of science, which is extremely messy and not at all packaged like the way we learn it in school, as a list of already-proven facts that are written in stone and will be true forever. Don't get me wrong, it's okay to operate on that level for some things. A ball dropped near the surface of the earth will accelerate at 9.8 m/s/s. But when we get to the more fundamental stuff where we ask "why" something is happening (instead of just describing what is happening) you really need to ask before hand "what level of approximation are you willing to tolerate". The answer to "why" becomes vastly different and ever changing. Scientists operate on that level all the time. And that doesn't even get into the issue of linguistics and classifications, which really are just arbitrary things we create to give order to our world and are not fundamental to anything in the universe, like "What is a planet" and "What is a moon" and stuff like that; those are just descriptions we made up out of whole cloth, and as such, are subject to whatever whim we want when setting the parameters. --Jayron32 11:58, 28 August 2020 (UTC)

I am rather reminded of Lord Ernest Rutherford's quip that "All science is either physics or stamp collecting". The school system does have a certain focus on the stamp collecting. (Not to say that there isn't real science outside of physics, though.) --184.146.89.141 (talk) 18:22, 28 August 2020 (UTC)

Watch Richard Feynman discuss the question "why" something is happening.  --Lambiam 19:16, 28 August 2020 (UTC)

Well, and of course there are two, non-overlapping, definitions of the word "Why?". One could be asking "what is the antecedant cause of X?", as in "Why did the ball roll down the hill?" Or one could be asking "for what purpose did "X" happen?" For example "Why did you kick the ball down the hill?" Science is really only concerned with the first set of whys. The why of the second kind presuposes an intelligence to have purpose, and laws of nature do not presupose such things. --Jayron32 13:00, 1 September 2020 (UTC)

Just look at the Plutonic fights and ongoing controversies over the definition of "planet". Any measurement-derived classification boundary in the natural sciences is bound (sorry) to have a certain degree of arbitrariness.  --Lambiam 10:03, 28 August 2020 (UTC)

The working definition of "moon" is a non-star that orbits another non-star and is more or less the junior partner in the relationship, meaning the primary body's gravitation is the dominant factor. The universe doesn't care what names we give to things, so like just about any human classification there's a grey area. At some point the bodies' masses approach equality and they both have a strong gravitational effect on the other, as with Pluto and Charon, and then you might want to call them a double planetary system instead. But every moon tugs back on its primary because that's how gravity works; here on Earth the Moon tugs on us and causes tides. And anything can theoretically have a moon if something stays inside its Hill sphere, though at some point it gets kind of silly to bother classifying it as a moon, in particular because it's not likely to stay there for a long time (in astronomical terms). At tiny enough scales, it will be easily perturbed by other astronomical bodies, radiation, and/or the galactic tide. --47.146.63.87 (talk) 09:33, 30 August 2020 (UTC)

Would a frozen sauce pouch defrost faster in room-temperature water or room-temperature air?

I have a watertight plastic pouch of sauce. The sauce is still liquid despite spending months in my freezer.

Imagine I had two of these pouches, both identical, and I submerged one in room-temperature water and the other I left on the countertop in room-temperature air. Which of those two pouches would reach room-temperature faster? --Aabicus (talk) 21:01, 28 August 2020 (UTC)

Water. See: Thermal conduction 107.15.157.44 (talk) 21:09, 28 August 2020 (UTC)

It will certainly start warming faster in the water, but if you're talking about a small volume of water in a pan, say, then the water is getting cooler as the pouch warms up, so it will tend to reach a thermal equilibrium temperature cooler than the water originally was. You therefore need to start with water that is warmer than room temperature. The air in the room is circulating and being replaced by normal ventilation, so while it will help to use warm air, the pouch will eventually come close to room temperature anyway. --184.146.89.141 (talk) 21:34, 28 August 2020 (UTC)

As heat flows from the water to the pouch and thereby lowers the temperature of the water, heat will also start flowing from the air to the pot and its watery content. Therefore there is no theoretical need to start at a higher temperature for the water than room temperature; in the limit all will have the same temperature. However, also theoretically, the shared limit of thermal equilibrium between all connected systems (air, pot, water, pouch) is never reached but only approached. For submersion in water, the initial incline may be much steeper, but the pouch temperature curve may begin to flatten out sooner, only to be overtaken by the curve for the air case; this could happen, for instance, if the thermal conductivity of the pot is extremely low.  --Lambiam 11:41, 29 August 2020 (UTC)

All this answers the detailed question, which does not match the title's question, answered already by 107.15.157.44 (under the somewhat safe assumption that "room temperature" is significantly above 0°C). Tigraan^{Click here to contact me} 16:05, 31 August 2020 (UTC)

Theory aside, practical experience shows that frozen food thaws faster in a sink (or pot, etc.) full of water. Perhaps thermal dissipation from water to air is also a factor. 107.15.157.44 (talk) 21:51, 28 August 2020 (UTC)

You might find our article on Sous vide interesting. It talks about heating the contents of plastic pouches in water. Zindor (talk) 21:53, 28 August 2020 (UTC)

August 29

Confused about how much lead is in our bodies

I'm confused about a sentence in the Lead poisoning article:

Since the normal Pb²⁺ concentration in the extracellular fluid is low (the adult average is 120 mg but rates vary greatly by country.), even a low increase in Pb²⁺ concentration has a significant positive effect on the blockage of NMDA-receptors.

The article talks about how there is no safe amount of lead exposure and "Lead has no known physiologically relevant role in the body", then says our bodies contain 120 mg, which seems like a lot. I don't know how to access the cited source and I'm having trouble finding a resource that confirms that we have that much lead in our bodies. Can anyone clear up the confusion? Cheesycow5 (talk) 15:38, 29 August 2020 (UTC)

I agree it is confusing, and I wonder if it is correct. It is strange to quote a mass as representing a concentration. Estimating the body weight of an adult non-elderly male at 75 kg, and using the formulas from Extracellular fluid and Body water, the amount of extracellular fluid should be something like 60% of 75 kg × 0.6 = 27 kg. 120 mg on 27 kg is 4.4 mg/L. For comparison: the article Lead poisoning states: "Authorities such as the American Academy of Pediatrics define lead poisoning as blood lead levels higher than 10 μg/dL."¹⁸ That amounts to 0.1 mg/L. The link to the cited source does not work, and "World Health Organization 2000" is not enough to identify the specific publication. The WHO publication Nutrients in Drinking Water does mention "120 mg/L" several times, but each time for the concentration of sodium, and not as an average but as a ceiling.  --Lambiam 17:39, 29 August 2020 (UTC)

Thanks for the detective work. I'm guessing, in any case, it should be removed since it doesn't properly cite a source for the claim. Cheesycow5 (talk) 18:37, 29 August 2020 (UTC)

I went ahead and removed that sentence. Cheesycow5 (talk) 21:01, 29 August 2020 (UTC)

There's an error somewhere, arithmetic is wrong. Sagittarian Milky Way (talk) 00:46, 30 August 2020 (UTC)

References

August 30

Will social distancing meant to curb COVID-19 cause common cold viruses to go extinct?

COVID-19 spreads better than common cold viruses. If we reduce the R-number for COVID-19, then we should also be reducing the R-number of the other common cold viruses. But because the R-number of these other common cold viruses is lower to begin with, they n umber of people with the common cold should decline exponentially fast. So, will the other common cold viruses go extinct? Count Iblis (talk) 03:26, 30 August 2020 (UTC)

. Basic reproduction number gives 2–6 for COVID-19 and 2-3 for common cold. To be fair, it doesn't try to distinguish different viruses and the source for common cold seems totally crap, but since you asked the question, what are your sources for your fundamental basic assumptions? Nil Einne (talk) 05:55, 30 August 2020 (UTC)

Their going extinct is a very strong demand. For one thing, as you can see, many people make a mockery of the social distancing advice. And, inasmuch as it has a noticeable effect, you can expect even more people to ignore it, so it is not at all clear that the effective reproduction number will go down by enough and long enough to have much effect. Then, there may be zoonotic reservoirs that are not affected at all.  --Lambiam 10:29, 30 August 2020 (UTC)

It should be noted that the expectation that we cause any disease pathogen to go extinct should not even be considered. In all of human history, exactly one global human diseases have been made entirely extinct: smallpox. So, discussions of something as porous and uncontrolled as general "social distancing" causing any disease to go extinct, where the concerted effort of all of humanity has caused exactly one disease to go extinct, well, those sorts of presumptions have no basis in reality. --Jayron32 16:13, 31 August 2020 (UTC)

Correct. Certainly concerted efforts can bring about regional extinction of previously pervasive pathogens, and certainly that is the hope with COVID19 and vaccination. Measles, for example, is extremely contagious and used to be a common childhood illness. Prior to vaccination programs, there were half a million to a million annual cases of measles in the US per year. Following vaccine introduction in the mid-1960s, the annual infection rate dropped extremely quickly, basically never hitting 100,000 annual cases after 1968, and from the 1990s until recent anti-vaxxer caused outbreaks, there were less than 1000 cases per year in the US, and it was essentially functionally extinct here. Aggressive vaccination can lead an extremely contagious pathogen to being something present only as very small background numbers. --OuroborosCobra (talk) 18:48, 31 August 2020 (UTC)

Well, polio may be on the way out - the final eradication is held up mostly by political difficulties in the few states that still have polio cases (and are politically very unstable). But this is only possible for pathogens that have no zoonotic source, and that are relatively stable. --Stephan Schulz (talk) 21:20, 31 August 2020 (UTC)

Why didn't any Atlantic tropical cyclone on record reach 7.1°N? (1851-now)

List of near-Equatorial tropical cyclones shows at least one under 2.9 degrees from the equator in all 4 sides of the Indian Ocean and 2 out of 4 semihemispheres of the Pacific. Sagittarian Milky Way (talk) 23:18, 30 August 2020 (UTC)

Because it's an exceedingly rare event anywhere in the world, and it should not be expected to happen; where it has happened in other ocean basins has been so rare as to be considered a fluke, and should not be used to extrapolate expectations. --Jayron32 15:24, 31 August 2020 (UTC)

August 31

Mean/Median U.S. income

Does the U.S. government publish an accepted national mean or median (or both) yearly income per person? How about hourly income? I've found many data sources at data.census.gov that often contradict one another. So, I can easily state that the average person is currently making $11/hour (from one source) or $27/hour (from another source). I just want to know which one the government accepts as the primary source that they use. By "they", I primarily mean Congress. 97.82.165.112 (talk) 17:41, 31 August 2020 (UTC)

I believe you'll find the best data from the Bureau of Labor Statistics, specifically the National Compensation Survey. --Jayron32 17:59, 31 August 2020 (UTC)

Mean and median are great, but you need the 'range' for context. See Section 14 (c) of the Fair [sic] Minimum Wage Act of 2007, it details sub-minimum wages for disabled people. A great injustice that was first put into law in the Fair [sic] Labor Standards Act of 1938. Zindor (talk) 01:36, 1 September 2020 (UTC)

Hourly income is very different from hourly wage. Someone who has a full-time job of 40 hours per workweek for 50 weeks a year works 2000 hours per year, but a year has on average 8766 hours, so their hourly income (measured by clock hours) is only the ²⁰⁰⁰/₈₇₆₆^th part of their hourly wage (measured by hours worked), which is less than a quarter.  --Lambiam 12:24, 1 September 2020 (UTC)

I've never heard of "hourly income" as being measured across all hours a person is alive. Can you show a link to a source that gives this definition? As far as I know, it is only calculated across contract hours. I made a good faith search for any definition that draws the distinction you provide, and can find none. Hourly income is the same thing as hourly wage. --Jayron32 12:52, 1 September 2020 (UTC)

It may be unusual for the time unit of hours, but "monthly income" is income per calendar month, not per month of contract labour delivered, and likewise "dayly income" is income per calendar day, not per day of contract labour. "Income" includes other things than wages from wage slavery, such as social security benefits and the business profits of a self-employed person. A statement such as that "a daily income of $1-2 was the most prevalent standard of living in the world in 2001"^[3] refers to income per calendar day; most people at this subsistence level are not employed. This is sometimes inconsistently applied, like defining daily income as weekly income divided by 5 (the number of workdays in a workweek). But how would you (or anyone) define the hourly income of a retired writer or artists who lives off the royalties of their past work, or the slumlord who lives off the rent received?  --Lambiam 15:52, 1 September 2020 (UTC)

I'm not saying you've not invented for yourself a self-consistent way of using some bit of terminology. I'm saying your invention doesn't exist in widespread use outside of this conversation we're having now. What I am saying is "produce a source that uses the phrase "hourly income" in a way that makes it clear and unambiguous they are not merely using it as a synonym for "hourly wage" or draws some meaningful distinction between the two". "I think it's logical..." is not a source. Please produce a source. --Jayron32 16:06, 1 September 2020 (UTC)

Imagine getting a job, agreeing to $20/hour, and then having the boss explain that if you extrapolate it out over your lifetime and then work back, he only has to pay you $1/hour. But, now that I think of it, that does happen in education. I often take yearly contracts for universities. We agree to a set salary, such as $60k for the year. But, because they are closed for the summer, I don't get paid for those four months. That is 1/3 of the year, so my actual salary is $40k. You have to read the fine print on education contracts because the listed salary is rarely the actual salary (and taxes haven't even come into it at this point). 97.82.165.112 (talk) 18:37, 1 September 2020 (UTC)

I work in education, and my contract salary is delimited per 10 months. I don't have an hourly wage because it is a salaried position. I am under long-term contract for working 10 months and getting paid a certain amount of money over those 10 months. --Jayron32 12:22, 2 September 2020 (UTC)

September 1

epidemiology of Covid19 in United States

Supposing there were a vaccine created for Covid-19 in the next few years, but only 40% of Americans took it, maybe because of genuinely harmful side effects, or pseudoscience, or whatever. Would the fraction of Americans who had been infected from Covid at least once eventually approach 60%, assuming the vaccine was almost 100% effective?Rich (talk) 07:48, 1 September 2020 (UTC)

That's not how herd immunity works. Somewhat simplified, if R0 is around 3 (which it seems to be for COVID-19), then every patient infects 3 others in a "virgin" population. If 2/3rds of people are immune for any reason, then that patient will only infect one other - the other two "transmission opportunities" fall on fallow ground. In that case, the number of infected will not grow (and if the number of immunes increases further, which it will naturally, each patient will infect less than one new case, and the number of new infections will go down exponentially). That's why basic herd immunity is computed as 1/R0. So you need 40% of vaccinated people, plus 26.6% of other immunes (i.e. people who recovered from infection). And if you manage to decrease actual R by other means (masks, social distancing, quarantine, ...) you may get away with even fewer cases. All this is assuming that recovered COVID patients are largely immune - something that seems likely, but we are not quite sure of. --Stephan Schulz (talk) 08:44, 1 September 2020 (UTC)

A relevant term here is "herd immunity threshold" (HT), which is the fraction of the population that needs to be immune for an infectious disease to push the effective reproduction number below 1. HT equals 1 – 1/R₀, the complement of 1/R₀. It is usually expressed as a percentage, so if R₀ ≈ 3, HT is about 67%. There are a few documented cases of recovered patients who were re-infected. The immunity conferred by vaccines does not last forever either, which is why some experts are warning COVID-19 may perhaps never be eradicated completely.  --Lambiam 09:46, 1 September 2020 (UTC)

• Notice that even though the infected population goes down once the immune population reaches 1-1/R (whether by vaccination or going through the disease) the epidemic will still infect a few people while dying down, so the eventually-infected population is higher than 1-1/R-vaccinated. For the gory mathematical details (under certain assumptions etc.), see the $r_{\infty }$ in Compartmental_models_in_epidemiology#The_SIR_model (the model does not include vaccination during the epidemic but I would conjecture the answer is not too wrong if you take $r_{0}$ as the proportion of vaccinated). Tigraan^{Click here to contact me} 12:54, 1 September 2020 (UTC)

Deer and goat hybrid is possible?

I've heard it's written in Mishna that it's possible but I'm not sure if it reflects reality or science. --ThePupil (talk) 12:26, 1 September 2020 (UTC)

It could be possible, but i wouldn't bet on it. Deer and goats are in different families, (Cervidae,Moschidae,Tragulidae) for deer and Bovidae for goats, so the cross would be an Interfamial hybrid. Zindor (talk) 12:43, 1 September 2020 (UTC)

It's very unlikely, given how rare interfamilial hybrids are. Most hybrids can only occur within the same genus, and I can't think of an interfamilial hybrid in mammals. List of genetic hybrids has none listed. --Jayron32 12:47, 1 September 2020 (UTC)

Thanks. Just want to note that Horses and donkies are also from different families, and still we may see the results exist as mules or hinnies.--ThePupil (talk) 14:59, 1 September 2020 (UTC)

They are absolutely not from different families. Horses and donkeys are both from the same genus even, Equus. As I said, there are no examples I can think of for viable mammal hybrids from different families. There may be some from different genera, but even so, the vast majority are different species within the same genus. --Jayron32 15:07, 1 September 2020 (UTC)

I thought they are different, because of what I read on this article on Wikipedia: "Donkeys have 62 chromosomes, horses have 64 chromosomes, and mules or hinnies have 63 chromosomes". So they are from the same family with a different number of chromosomes? --ThePupil (talk) 15:19, 1 September 2020 (UTC)

Yes, the number of chromosomes is not necessarily consistent between species even if they are in the same genus. In the case of horses and donkeys, they are both members of the same genus, being Equus. Family is one layer yet again higher up the Linnean classification system above genus. So everything that is part of the same genus is also part of the same family (and class, and order, and phylum, etc) --Jayron32 15:42, 1 September 2020 (UTC)

Thank you. I've learnt something new. So basically we cannot say surely that cross between deer and goat can be. Right? Do we know an animal hybrid of two families?--ThePupil (talk) 19:52, 1 September 2020 (UTC)

No, no one in history has ever produced a cross between a deer and a goat. You are incorrect on that. Deer and goats are members of entirely different families, deer being members of the Cervidae family and goats are members of the Bovidae family. Given that, as I noted above, there has not ever been before a mammalian hybrid from such distantly related animals, it is unlikely there to ever be one in the future either. --Jayron32 12:13, 2 September 2020 (UTC)

Some wild horses also have a different number of chromosomes. Ruslik_Zero 18:48, 1 September 2020 (UTC)

Do carrot tops contain toxic alkaloids?

The section § Consumption of the Wikipedia article on carrots states that "some sources suggest that the greens contain toxic alkaloids", citing two sources. Maybe I am overlooking something, but I cannot find this claim in either source. Is there some scientific basis for this – other than that almost any vegetable contains trace amounts of alkaloids?  --Lambiam 15:05, 1 September 2020 (UTC)

Some possible additional sources can be found here. This source here states that the alkaloids in question are pyrrolidine and daucine. --Jayron32 15:10, 1 September 2020 (UTC)

So "all alkaloids are bad because substances like caffeine and cocaine are alkaloids".^[4] Next thing you know people will start snorting carrot tops instead of smoking banana peels.  --Lambiam 07:37, 2 September 2020 (UTC)

I'm afraid I said nothing of the sort. I'm not sure where you think I did? --Jayron32 14:43, 2 September 2020 (UTC)

Lambiam wasn't quoting you, but rather the piece from carrotmuseum. Even there it was described as a "myth".

I'm curious now what "daucine" is. I don't see any recent entries on a naive search. "The Plant Alkaloids", by Thomas Anderson Henry, whoever he may be or have been, says the following, in a typeface that suggests it's a rather old book:

Carrot leaves contain, according to Pictet and Court, pyrrolidine and an alkaloid, DAUCINE, C₁₁H₁₈N₂. The latter is a colourless oily liquid, b.p. 240^o–250^o, [a]_D +7.74^o in ether, having an odour like that of nicotine, but which does not give the pyrrole reaction.

No structural formula is given. My guess would be that this substance now has a different name, which is why I don't find recent info on it, but I don't know what it would be. If it could be found, we should create a redirect. --Trovatore (talk) 17:44, 2 September 2020 (UTC)

SciFinder lists that name as having CAS# 1399-02-6 with a matching molecular formula and approximate boiling point (corrected from a different pressure), but no structure or other synonyms. DMacks (talk) 03:38, 3 September 2020 (UTC)

Thanks. Seems to be behind a paywall with no obvious price list :-) --Trovatore (talk) 05:54, 3 September 2020 (UTC)

This chemicals list, volume A–G of a two-volume book, has "daucine" as the only name for [1399-02-6]. The number does not occur in the H–Z volume, so it seems that there is no current synonym and that the dearth of results is due to its lack of popularity.  --Lambiam 07:18, 3 September 2020 (UTC)

The name undoubtedly derives from the genus name of the binomial name of the carrot, Daucus carota.  --Lambiam 07:31, 3 September 2020 (UTC)

The Dictionary of Food Compounds gives structural descriptions where known, but has for daucine: "Struct. unknown".  --Lambiam 07:41, 3 September 2020 (UTC)

It was a direct quote from the carrotmuseum page – the top result of the Google search. While it mentions "This popular myth", presumably (the antecedent is not made explicit) referring to the idea that carrot tips are not edible, the bit I quoted about caffeine and cocaine is in a different section and not identified there as being questionable.  --Lambiam 07:08, 3 September 2020 (UTC)

This is the publication where Pictet & Court announce a novel alkaloid and name it daucine.  --Lambiam 08:37, 3 September 2020 (UTC)

That's cool. Fun to look at this old stuff sometimes. I'm a little shocked that no grad student has bothered to work out the structure in all these years. Could be a master's thesis, maybe? --Trovatore (talk) 18:20, 3 September 2020 (UTC)

Ah. I think this was the page I saw, or possibly a mirror of it. It says Myth #1: Carrot greens contain alkaloids (which are toxic bitter compounds produced by a plant) and all alkaloids are bad because substances like caffeine and cocaine are alkaloids. Looks like it was directly quoting, and attempting to refute, the carrotmuseum line. --Trovatore (talk) 07:16, 3 September 2020 (UTC)

September 2

Why do mice like peanut butter so much and where did the cheese thing come from?

Does it have the right percent of macronutrients to survive on as little as possible or something? Is it missing any mousie essential nutrients? Do they still need water if they only have fresh peanut butter that hasn't lost water yet? Would they eat it till they're obese if they could? Or even gorge till they puke? Or just stop when they're not hungry? Do they hide some for later like squirrels? Sagittarian Milky Way (talk) 02:36, 2 September 2020 (UTC)

According to this article (cited in our article on the house mouse), rodents can't actually vomit. PaleCloudedWhite (talk) 07:55, 2 September 2020 (UTC)

A quick Google search indicates that peanut butter is rich in nutrients that mice crave. We used to bait our mouse traps with a tiny dab of the stuff, or sometimes a tiny bit of bacon could also do the trick. ←Baseball Bugs ^{What's up, Doc?} carrots→ 09:10, 2 September 2020 (UTC)

As to where the mice and cheese meme originates, in The Taill of the Uponlandis Mous and the Burges Mous of 1480, the town mouse dines on delicacies unknown to the country mouse; "chies and butter" get the first mention [5]. To be fair, they also eat candle wax, so perhaps it's the fat content - candles were made of tallow in those days "a rendered form of beef or mutton fat". Peanut butter wasn't invented until 1884, whereas both mice and cheese have been part of the human experience for millennia. Alansplodge (talk) 16:59, 2 September 2020 (UTC)

Dictionaire Oeconomique, Or, The Family Dictionary (1729) p. 128: "MOUSE; a little four footed Animal, so common and so universally, known as to need no Description... [they] are injurious in and about Houses, by eating Cheese, Meat, and other Provisions of the Houshold". Alansplodge (talk) 17:11, 2 September 2020 (UTC)

I recall reading somewhere that the association of mice and cheese comes from pre-20th century Western culture, where cheese was one of the foods that would be commonly found stored in a pantry. Remember, no refrigeration. It said mice don't have any real preference for the stuff, but they're omnivores and will eat what they can get. Flour and similar things can't be easily eaten by rodents because they can't bite them into chunks with their incisors. --47.146.63.87 (talk) 22:09, 3 September 2020 (UTC)

Universe density without expansion

Could it be argued theoretically that without accelerating expansion of the Universe its density might gradually (possibly over some long period) increase (due to various matter-forming and shedding processes) to the point of becoming high enough to conduct sound waves? And is that acceleration actually essential to offset possible density increase which otherwise may overtake "slower" expansion, without acceleration? Brandmeister^talk 14:40, 2 September 2020 (UTC)

Matter-energy can't be formed. Expansion without any accelerating magic decelerates and will expand forever, stop on infinity AD or stop before infinity AD and go back to infinite* density. Probably tiny gray areas where outcome depends on quantum fluctuations too. Sagittarian Milky Way (talk) 14:57, 2 September 2020 (UTC)

I mean increase in gaseous density in particular, because various astrophysical processes generate gases, like hydrogen and oxygen. Presumably without accelerating expansion this continuous buildup of gases and molecules would affect average density of the Universe, making the space more dense. Brandmeister^talk 18:21, 2 September 2020 (UTC)

I'm not aware of any astrophysical processes that result in a net production of hydrogen - theoretically, Hawking radiation might occasionally produce a proton or electron around a black hole, but that would be (at least over normal cosmological time scales) be more than balanced by hydrogen falling into black holes. Oxygen is produced by stellar nucleosynthesis, but at the cost of using up much larger amounts of hydrogen. Typically, interstellar gas goes down as galaxies age (it's used up in star formation). --Stephan Schulz (talk) 19:57, 2 September 2020 (UTC)

Supernovae explosions, for example, are known to produce some elements (and reportedly, shock waves that compress gas clouds to aid new star formation). This raises an additional issue of possibly insufficient space for new stars and cluttering in the absence of Universe's expansion. Wow... unless there's something wrong with that assumption. Brandmeister^talk 20:42, 2 September 2020 (UTC)

Supernova explosions produce some elements, but not from nothing. They just rearrange existing matter into new configurations. Also, after a supernova explosion, there usually is one star less. --Stephan Schulz (talk) 20:53, 2 September 2020 (UTC)

But what about my question per se? Would the density increase without accelerated expansion? Brandmeister^talk 08:06, 3 September 2020 (UTC)

Matter & energy isn't being created or destroyed. If the size of the universe was held fixed, the overall mass density would be constant. That said, the local mass density can change, especially as gravity causes clouds of hydrogen and helium to condense into stars. The stars are very dense, but the surrounding area is then somewhat depleted. Stars convert hydrogen and helium into heavier elements. Over time the amount of hydrogen and helium will decrease and the amount of heavier atoms will increase. The total number of atoms is likely decreasing. Certain esoteric particles, such as neutrinos, are probably accumulating over time (however, their overall density will still be very low). Dragons flight (talk) 10:20, 3 September 2020 (UTC)

Still, there is conversion of energy into mass per energy-mass equivalence. Would it contribute to the density increase in a fixed-sized Universe? A supernova explosion shoots elements and debris into space. Supernovae explode relatively rarely while new stars are formed continuously in the entire universe. Apparently, for every single supernova explosion at least several new stars emerge - which may be another issue in a fixed-size universe. Brandmeister^talk 11:40, 3 September 2020 (UTC)

No, there isn't. Mass-energy equivalence means that energy already has mass. Everything else being equal, an object will weigh (very slightly) more when it hot than when it is cold because the thermal energy contributes (very slightly) to the total mass. You can convert energy into matter, but you haven't actually changed the total mass. Dragons flight (talk) 13:30, 3 September 2020 (UTC)

I'm reminded of the now discredited steady-state model which had matter created to fill the void created by expansion of the universe. Remove the expansion, keep the creation of matter and you're all set.

Steady state is dumb. It expanded from immense density and possibly bounces forever is simpler. Bouncing forever was later ruled by expanding forever of course. Sagittarian Milky Way (talk) 16:06, 3 September 2020 (UTC)

September 3

valved n95 respirators

It's still very hard to get unvalved n95 respirators, but valved ones (not recommended for virus protection because the exhaust port spews virus if you are infected) are getting easier to find. Home Depot near here has some. 1) Does snipping out the valve and patching the hole with a rubber seal sound like a reasonable fix to this issue? The seal would probably be a bit of cut-up nitrile glove hot-glued into the mask. From the picture I think the hole would be maybe 15mm diameter. 2) Why after all this time are regular n95 still so hard to get? There's no toilet paper shortage any more, for example. Thanks. 2601:648:8202:96B0:0:0:0:DDAF (talk) 05:47, 3 September 2020 (UTC)

I once ordered and wore a valved N95 (FFP2 in the EU) mask during pandemic. The valve there is for a reason, presumably otherwise they would not be certified as N95 (FFP2). My understanding is that "spewing" is negligible compared to the issue of heating and excess moisture buildup in a valveless mask (particularly in hot summer). Any custom modification of a N95 mask may breach its integrity and resistance. Brandmeister^talk 08:19, 3 September 2020 (UTC)

• For (2), the comparison does not make much sense. Toilet paper shortages were due to (a) panic buying resulting in a build-up of stock among consumers, (b) a change in the products consumed (toilet paper bought by companies, theaters etc. is not the same product as bought by private individuals). (a) takes care of itself within a few weeks because the demand spike is followed by a demand gap, (b) can be fixed by a (supposedly easy) retooling of existing machinery. On the other hand, the demand for masks has increased dramatically since February/March and will remain at a higher-than-before level for quite some time; it is not easy to expand production ten-fold at short notice, even with big price incentives. Tigraan^{Click here to contact me} 08:45, 3 September 2020 (UTC)
• Most studies indicate such valved masks are not terrible in spreading the virus, as long as the valves are properly used. This is just one example of many articles on the subject. The valved mask is not as good as the full N-95, but it is, within error bars, comparable to, and in some cases better than, things like cotton masks and surgical masks. In short: The valved mask is not as good as the full N-95, but neither does it "spew virus", and it is comparable to the wide range of other kinds of masks on the market, and much better than things like bandanas and T-shirt material buffs. If you can't get the fitted N-95, the valved one may be among your next best options. --Jayron32 11:47, 3 September 2020 (UTC)

Why is surgery done with only surgical masks? Sagittarian Milky Way (talk) 15:57, 3 September 2020 (UTC)

Sometimes they also use surgical knives.  --Lambiam 21:13, 3 September 2020 (UTC)

It gets worse, i've heard some rogues even wear surgical gloves! Zindor (talk) 21:46, 3 September 2020 (UTC)

Chemistry, Nitrogen and it's compounds form three

How is nitrogen gas prepared ? — Preceding unsigned comment added by Emmanuel ngetich (talk • contribs) 17:58, 3 September 2020 (UTC)

Mostly by taking it from the air, of which it is the overwhelmingly major constituent. The air separation article describes the major processes for doing it. DMacks (talk) 18:08, 3 September 2020 (UTC)

Though, pertaining to the section title, nitrogen compounds are rarely if ever prepared from nitrogen gas, because the dinitrogen triple bond is very strong and takes a lot of energy to break apart. Instead, ammonia or other nitrogen compounds are used as the nitrogen source. Ammonia is produced today with the Haber–Bosch process, one of the most important inventions of the 20th century and a major industrial process. --47.146.63.87 (talk) 22:14, 3 September 2020 (UTC)