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October 27

Taxon presentation

Why does Wikipedia's Taxon Box mix cladistic terms with the older 'KPCOFGS' presentation. While referencing the same facts, the 2 structures do not mix well, tho seeming to do so when 'boxed'. Perhaps better would be to have a different format tagged with a brief note on the differences when both are used. Regards, Larry Williams ```` — Preceding unsigned comment added by 96.54.23.37 (talk) 17:28, 27 October 2021 (UTC)[reply]

You'd better discuss this on Wikipedia_talk:WikiProject_Tree_of_Life. Ruslik_Zero 20:07, 27 October 2021 (UTC)[reply]

And doing so, it may help to give concrete examples of problems resulting from the use of KPCOFGS labels for clades. --Lambiam 22:39, 27 October 2021 (UTC)[reply]

October 28

Plants: why are there no red flowers at Arctic latitudes?

Just so we're on the same page: Arctic is 66 - 90 Lat, Tundra is 70 - 90 Lat, and Taiga is 50 - 70 Lat. Anyhoo, Wikipedia has a category page on Flora of the Arctic. On my computer, a quick mouseoverover all of them, can show a picture without clicking into the article. Roughly, 45% are white flowers, 45% yellow flowers, and the rest a bluish/purplish color. No red. And petals being real small. Why don't red-colored flowers exist that far north? And fyi, I did ask a biology professor at my university this, and 1 who specializes in plants the most. I'll post the his response later, but I want a 2nd opinion. (The answer he gave me, seems to be a generic answer to any "Why doesn't X-flower, exist in Y-location?"). So I wanna see what you guys think. 67.165.185.178 (talk) 00:50, 28 October 2021 (UTC).[reply]

The University of Lapland suggests bilberry which has a pinkish-red flower, also bog bilberry, creeping azelea (pink), Lapland rhododendron (purple), moss campion (pink), mountain heath (initially red, later purple) and perversely, yellow mountain saxifrage which is "often yellow with red spots but occasionally reddish yellow or even purple". [1] But I agree, there are no big red flowers. Alansplodge (talk) 11:57, 28 October 2021 (UTC)[reply]

This page seems to show a plant with tiny red flowers in the third picture down, but does not name them. --Jayron 32 12:11, 28 October 2021 (UTC)[reply]

Papaver nudicaule may have a range that extends into the arctic, and has red variants. --Jayron 32 12:14, 28 October 2021 (UTC)[reply]

A quick Google search shows that there are differing hypotheses about the relationship between flower colouration and pollinators, see Why red flowers are not invisible to bees for example, but I couldn't find anything specific to the Arctic. Alansplodge (talk) 12:29, 28 October 2021 (UTC)[reply]

My trusty copy of WILD FLOWERS AT A GLANCE shows that the UK also lacks any big red wild flowers, with the obvious exception of the field poppy. Lots of pink or purple ones, but only one which is red, and we're not very close to the Arctic. Alansplodge (talk) 11:58, 29 October 2021 (UTC)[reply]

Wild Flowers at a Glance is one of my favourite botanical works. The grouping by colour is especially helpful. DuncanHill (talk) 01:09, 2 November 2021 (UTC)[reply]

Sorry for the late response been having Internet problems at home so on a work computer. But the plant professor said red flowers don't exist in northern latitudes due to pollination. And the example he used was hummingbirds. So no hummingbirds up north pollinating red flowers. But now my question raises, are hummingbirds correlated with red flowers or something? And Alansplodge pointed out bees and pollinations. So do flowers need to be pollinated by both bees and birds, or only 1 of them? What's the connection between the 3? Thanks. 96.90.97.153 (talk) 14:48, 29 October 2021 (UTC).[reply]

Different plants require different pollinators. The different colors (including some outside the range of human vision) attract different pollinators. So, even if a plant could survive in a particular environment, it will not spread there if the pollinators attracted to its color patterns cannot survive. --Khajidha (talk) 15:41, 29 October 2021 (UTC)[reply]

Yes, hummingbirds are well-known to prefer red. Yellow, bees, purple, bumblebees, white, bats. Abductive (reasoning) 01:34, 31 October 2021 (UTC)[reply]

I recommend the OP read this recent book^[1] by Timothy Walker. Although it doesn't have a section specifically on the arctic, it points out 1) that wind and water can be pollination vectors and will not depend on colour 2) that red is assumed to be the default colour for bird-pollinated flowers 3) that for insect pollination the most important aspect is to contrast with the predominately green foliage (so yellow or white flowers) and that an insect's compound eye provides poor resolution. The full story is therefore quite complicated! Mike Turnbull (talk) 13:27, 31 October 2021 (UTC)[reply]

References

^ Walker, Timothy (6 October 2020). Pollination: The Enduring Relationship Between Plant and Pollinator. Princeton University Press. pp. 1–224. ISBN 9780691203751.

Ah yes, Wikipedia's article on pollination does have a picture caption that says hummingbirds and red flowers, no citation though. I do recall most birds are blind to red, because of the Roy G Biv (red orange yellow --- indigo violet) is a little shifted. So what we see as blue, they see as purple. And therefore they can see ultraviolet where humans can't. And so flowers can be pollinated by more than 1 group? 67.165.185.178 (talk) 12:52, 1 November 2021 (UTC).[reply]

Wikipedia's Flora of the Arctic category contains Rubus arcticus, which according to our article has flowers that are pink, red or magenta. So that's at least one Arctic red flower. I think the hummingbird explanation is a red herring (lol) - here in the UK there aren't any hummingbirds, yet there is at least one red native wildflower that I can think of (Papaver rhoeas). PaleCloudedWhite (talk) 19:40, 1 November 2021 (UTC)[reply]

Another hummingbirdless red UK flower is Anagallis arvensis - commonly known as the scarlet pimpernel (ignore the non-typical images at our article). PaleCloudedWhite (talk) 19:53, 1 November 2021 (UTC)[reply]

Space shuttle - why didn't it use only Solid Rocket Boosters?

I know I'm not cleverer than the space shuttle designers but... why didn't the shuttle use more solid fuel boosters and do away with the space shuttle engines and the external fuel tank? Is the answer 'controllability'?Hayttom (talk) 02:13, 28 October 2021 (UTC)[reply]

The fire still has to come out after the solid rocket boosters eject, they are not moving fast enough to orbit at that point. If you put more boosters the acceleration might get too strong when they are light weight near the end, since solid rocket boosters cannot be throttled like the hydrogen engines are, at max air resistance to prevent air breaking the vehicle and near hydrogen engine cutoff to prevent acceleration from getting too strong. If you put more boosters but don't turn them all on ASAP you are doing an inefficient as you want the fuel and dumpable objects to leave as fast as possible, so long as you use it completely* and do not accelerate faster than you can bear. See gravity loss and the tyranny of the rocket equation. *I've heard hydrogen rockets explode (im?) if they burn to fuel exhaustion instead of being turned off. Also when you have achieved the objective you can turn them off, there is a small amount of extra usable fuel for margin of error. Sagittarian Milky Way (talk) 04:51, 28 October 2021 (UTC)[reply]

A propellant that burns at a predictable rate can be cast in a shape that provides a "hard-coded" variable thrust curve. The Space Shuttle Solid Rocket Boosters did exactly that, reducing thrust for a while mid-flight to avoid exessive stress at Max q. DMacks (talk) 05:24, 28 October 2021 (UTC)[reply]

Ah I didn't know that, I incorrectly thought the throttling was all orbiter. Sagittarian Milky Way (talk) 13:45, 28 October 2021 (UTC)[reply]

Isn't it the case that once a solid fuel rocket is ignited that you can't cut it off until all the fuel is spent? --Iloveparrots (talk) 05:51, 28 October 2021 (UTC)[reply]

Our solid-propellant rocket article says this is not strictly true any more. [2] is an article about some recent developments of on-demand (real-time-controllable) extinguish/reignite systems. DMacks (talk) 06:14, 28 October 2021 (UTC)[reply]

I need to brush up on my space advances. Sagittarian Milky Way (talk) 13:45, 28 October 2021 (UTC)[reply]

It it's definitely possible to get to orbit using only solids (Minotaur, Pegasus, Vega, Epsilon, Scout, Shavit etc etc etc), but you'll notice they all have one thing in common, they're small payload vehicles. This is to do with inefficiency of solids. They are inherently inefficient compared to liquid fuelled engines, and hydrogen engines in particular. This is the concept of specific impulse (Isp) Tl/dr; it's effectively a measure of the efficiency of a given engine/fuel. You need to get up to about 8 km/s to get to low earth orbit in an ideal case, in practical terms you need even more due to losses on the way up. The propulsion system with the highest Isp will need the least fuel, and thus the smallest rocket* to do this. To get something as massive as the shuttle to orbit with just solids, you'd probably meed an order of magnitude more solid fuel than it had. It's just not efficient. Now why you'd use them in the first place, hydrogen engines, whilst efficient, don't tend to put out all that much thrust. So you augment the trust off the pad with less efficient but high trust solids to minimise gravity losses early on. (*Due to the low density of liquid hydrogen, rockets that use it then to be quite physically large (compare hydrogen fuelled Delta IV with kerosene fuelled Atlas V), but they are small in terms of fuel mass) Fgf10 (talk) 08:09, 28 October 2021 (UTC)[reply]

Space Shuttle design process explains why they chose the hybrid solid rocket boosters and liquid tank and main engines. The design process itself was fraught with various political and budgetary concerns, and involved multiple agencies each with their own ideas. The final decisions were made, in part, as a compromise between various possible solutions, and the first paragraph of the section of that article titled "Final design" explains how the final design was arrived at. Notably, NASA would have preferred an all-liquid system, but the solid boosters were cheaper, and that ultimately is what led to including them at all. --Jayron 32 12:09, 28 October 2021 (UTC)[reply]

These look like truly excellent answers. (I ought to have discovered Space Shuttle design process. For my purposes I am going to mark this...

Resolved

.

How to get parrot to fly?

This is about my friend's mealy amazon parrot. The vet says he's overweight, so in addition to putting him on a low calorie diet she's been trying to get him to fly so he can work out. But he doesn't want to. The parrot is at least 25 years old and mostly flies like a spruce goose on the few occasions that something scares him and he takes off (other than that, he walks and climbs everywhere). We tried picking him up like a chicken and throwing him up into the air (bean bag underneath), but all he did was flutter his wings on the way down. This was making him really angry so we stopped doing that.

Does anyone have any tips for how to do it properly, or good links? Thanks. --146.200.107.70 (talk) 02:41, 28 October 2021 (UTC)[reply]

Who's been trying to get the bird to fly? The vet? Or your friend? ←Baseball Bugs ^{What's up, Doc?} carrots→ 04:18, 28 October 2021 (UTC)[reply]

My friend. The vet said that she needs to put him on a better diet (no more fast food scraps or soda) and get him more exercise. So my friend has been trying to get him to fly. Apparently he can fly a bit (if he falls off something or gets scared by a loud noise outside, he will fly a bit, like a chicken), but he chooses not to. --146.200.107.70 (talk) 04:32, 28 October 2021 (UTC)[reply]

There are lots of other ways to exercise a parrot[3] that might not irritate him. Clarityfiend (talk) 06:15, 28 October 2021 (UTC)[reply]

Lawless nature

In his book “The Religion of the Future”, Roberto Mangabeira Unger writes ❝[In the beginning of the universe, t]he laws of nature may not have been distinguishable from the states of affairs that they governed. Indeed, causal connections or successions may not have assumed a law-like form at all.❞. I searched our articles on cosmogony, scientific law, as well as some of the articles linked from there, but see no mention of this. Presumably, the idea was laid out in his (co-authored) book “The Singular Universe and the Reality of Time”, but our article says nothing about it. Is that just a crackpot idea or is there something to it? ◅ Sebastian 08:50, 28 October 2021 (UTC)[reply]

I do not think that sentence attempts to say much about physics. Maybe it is crackpot philosophy, but from my limited knowledge of epistemology, that sentence is basically tackling the question of what it means to be a "law" (of physics, of nature). The Stanford Encyclopedia of Philosophy has a page about that very topic, though I have a hard time reading past the intro.

The "professional scientist" view on those topics is summarized in the last sentence of the lead of scientific law: (...) in essence scientific laws are simply empirical conclusions reached by scientific method; they are intended to be neither laden with ontological commitments nor statements of logical absolutes. If that definition seems foolproof to you, you might want to have a look at the new riddle of induction. (Summary: a tribe in a remote Pacific island has no word for "green" and "blue", and they think of objects as "grue" or "bleen", meaning green now but they will appear green after a certain date (and vice-versa); how do you convince them that "blue" and "green" are more proper, more natural colors than "bleen" and "grue"?) Tigraan^{Click here for my talk page ("private" contact)} 10:04, 28 October 2021 (UTC)[reply]

There are physical aspects of the very early Universe that would seem to support Unger's statement (if I understand it correctly) in that they make the concept of time problematic. In terms of the standard cosmic time parameter: the quark-hadron transition occurs about 10⁻⁵ seconds after the "Big Bang". Before that, there are no bound systems from which one could build a clock or measure distances. At 10⁻¹¹ seconds, the electro-weak transition occurs. Before that there are no massive particles, hence everything moves on light-like trajectories with vanishing proper time. There's nothing physical that could define a finite proper time which would seem necessary to define causal sequences. Note that this is long after the Planck era. I take this from my notes on an article by Rugh & Zinkernagel in this book. --Wrongfilter (talk) 10:43, 28 October 2021 (UTC)[reply]

The OP's quote from Unger seems quite correct to me. You can think of a physical law as a kind of function that takes as its input an initial state of a system, and gives as its output the state of the same system at some later time. Put in the positions and velocities of the planets and the sun, and get out their positions and velocities in 1000 years. The law is an abstract thing that is decoupled from any particular state of the system, because it gives you the freedom to put in any initial conditions you like. However, this all depends on their being a smooth, classical spacetime manifold with a causal structure. If the very early universe had a quantum foam spacetime, there may be no way to talk sensibly about initial conditions or a later state. I'd say it's uncontroversial that this set of challenges exists when thinking about time and physical law in quantum cosmology. But there's no consensus around any particular solution or alternative formulation. There's a recent seminar here [4] where you can read abstracts talking about a few approaches. Here's an older paper by James Hartle where he attempts to clearly define the problem: [5]. --Amble (talk) 21:51, 28 October 2021 (UTC)[reply]

Note that Unger co-wrote The Singular Universe and the Reality of Time with Lee Smolin, who has some controversial views on these questions but is a very serious scientist and no crackpot. (These are areas where no consensus exists, and there may not be such a thing as a non-controversial view.) --Amble (talk) 22:08, 28 October 2021 (UTC)[reply]

Anaphylaxis biochemistry

What causes anaphylaxis compared to mild allergic reactions? Is it the amount of histamine released or is it related to where the histamine is released or are there other chemical involved too? 213.205.241.43 (talk) 12:15, 28 October 2021 (UTC)[reply]

It appears to be a potentially complex combination, as suggested by the abstract of this paper – involving not only the release of histamine, but also the action of enzymes and other effects. The root cause is the ample presence of antibodies for a specific antigen in some substance, exposure to which triggers the wild immune response, like a panic reaction, in a sensitized patient. --Lambiam 13:54, 29 October 2021 (UTC)[reply]

October 29

Afterglow lifetime change

Hi, I was looking for some references about afterglow lifetime. What may be the reasons that the lifetime of a sample changes from long to short, or short to long? For example, when the sample is synthesized, its lifetime is 1.0 s. After 2 hours, it's 1.5 s. After 8 hours, 1.4 s, and 16 hours, 1.3 s. Then it gradually stablizes at ~1.2 s. --Leiem (talk) 03:52, 29 October 2021 (UTC)[reply]

Which Afterglow (disambiguation) are you talking about? ←Baseball Bugs ^{What's up, Doc?} carrots→ 09:41, 29 October 2021 (UTC)[reply]

The reference to a synthesized sample strongly suggests a chemical substance, in which case "afterglow" is probably phosphoresence. Depending on the type of phosphoresence, the glow of persistent phosphoresence may last for hours after excitation, so the question is probably about short-lived triplet phosphorescence. I doubt the question allows for a uniform answer, but may depend on the nature of the synthesized material. Is it a polymer? Does the material have structure defects or impurities that can trap charges? Is there temperature dependence? If the temperature is not constant, this may already account for such variation. --Lambiam 13:02, 29 October 2021 (UTC)[reply]

Thank you for your reply. It is phosphoresence lifetime of a coordination polymer and the temperature is constant. --Leiem (talk) 14:15, 29 October 2021 (UTC)[reply]

I can't think of another reason than spontaneous changes in the crystallization structure, where molecules at the boundaries of regions may still switch their alliance before eventually stabilizing. If true, it should imply that charting afterglow lifetime versus real time gives graphs that are not correlated between different samples, and also that at a lower temperature reaching stabilization takes longer. --Lambiam 22:26, 30 October 2021 (UTC)[reply]

Sequenced inoculation

In Spanish flu, I find

What is sequenced inoculation? The article Inoculation is concerned mainly with smallpox. From what I understand, it is infecting healthy people and hope for the best. In the case of smallpox, it uses viruses from mild cases and it is done on the arm so that it is less agressive.

How was it done in the 1918 flu? What does "sequenced" mean here? Thanks. --Error (talk) 11:54, 29 October 2021 (UTC)[reply]

References

^ ^a ^b Hauck G, Gellis K (November 22, 2020). "We're celebrating Thanksgiving amid a pandemic. Here's how we did it in 1918 – and what happened next". USA Today. Archived from the original on November 21, 2020.

This contains several good sources, such as this one that defines "sequenced inoculation" as the avirulent strain was applied 2h before the virulent one. This is contrasted with co-inoculation, in which the two strains are administered at the same time. --Jayron 32 12:09, 29 October 2021 (UTC)[reply]

Thanks. Those results are mostly about yeasts or symbiotic bacteria where the inoculates produce a desirable effect which can be synergized by sequenced inoculation or co-inoculation of different variants. Reading https://eu.usatoday.com/in-depth/news/nation/2020/11/21/covid-and-thanksgiving-how-we-celebrated-during-1918-flu-pandemic/6264231002/ and https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2862332/ tells me that there were vaccines against influenza, but since virology was very primitive, they were actually against bacteria found in flu patients. They may have helped or not. So this "sequenced inoculation" was not about flu viruses, which was one of my puzzles. Still our article about inoculation is very centered on smallpox and says nothing of inoculating plants with bacteria or other uses. --Error (talk) 15:19, 29 October 2021 (UTC)[reply]

Influenza vaccine#Origins and development describes some success with the use of blood transfusions from recovered patients, presumably either the inactivated virus in their own blood or the antibodies themselves helped provide some vaccine-like protection to those so inoculated. --Jayron 32 15:34, 29 October 2021 (UTC)[reply]

The 1918-19 Spanish Influenza Pandemic and Vaccine Development says:-

Certainly none of the vaccines described above prevented viral influenza infection – we know now that influenza is caused by a virus, and none of the vaccines protected against it. But were any of them protective against the bacterial infections that developed secondary to influenza? Vaccinologist Stanley A. Plotkin, MD, thinks they were not... the vaccine developers had little ability to identify, isolate, and produce all the potential disease-causing strains of bacteria circulating at the time.

Alansplodge (talk) 18:15, 29 October 2021 (UTC)[reply]

Reduction potential

1. What is the reduction potential of (HgCl₄)^2- in seawater? 2. What is the reduction potential of mercury in seawater? — Preceding unsigned comment added by Horus1927 (talk • contribs) 12:44, 29 October 2021 (UTC)[reply]

Sound in non-expanding universe

In a purely theoretical thought experiment, would it be correct to state that without the universe expansion, matter density would gradually rise to the point where it would conduct sound waves from cosmic processes (Sun's activity, supernova explosions, etc)? Can Friedmann equations handle this? 212.180.235.46 (talk) 15:17, 29 October 2021 (UTC)[reply]

So, in a steady state universe, density would not be increasing (by definition, the universe is at a steady state and not contracting or expanding). In that case, meaningful sound would not be possible. In a contracting universe (perhaps caused by Gravitational collapse), ala the big crunch, then matter density would gradually increase, though whether anyone would be around to hear such a sound would make it moot, but presumably, at some point, such a universe would be able to maintain pressure waves one could define as sound; of course in the real universe, such a state did exist in the past, shortly after the Big Bang. See, for example, this article, which discusses what such an early universe would have sounded like. --Jayron 32 17:32, 29 October 2021 (UTC)[reply]

The assertion "the density of matter in the expanding universe remains unchanged due to a continuous creation of matter" in the steady state universe looks self-contradictory to me. How can a continuous creation of matter not increase the density of matter? If cosmological processes, such as nucleosynthesis and supernova explosions, continuously produce more elements, why the average matter density would not increase? Thanks. 212.180.235.46 (talk) 21:24, 29 October 2021 (UTC)[reply]

Jayron's initial sentence above is incorrect. Hoyle's steady state universe was expanding (because the expansion had already been observed and shown to conform to Einsteinian theory), but (as Amble says below) new matter, supposedly in the form of individual hydrogen atoms) was being continually created in intergalactic space at a rate that maintained the Universe's overall density. It was the states of density and the overall homogeneity and space-time isotropism of the universe (see Perfect cosmological principle) that were "steady", not its space-time dimensions, which were presumed to be infinite. {The poster formerly known as 87.81.230.195} 90.200.65.29 (talk) 23:09, 29 October 2021 (UTC)[reply]

Nucleosynthesis, supernova explosions, etc. don't create new matter; they transform lighter elements (mostly hydrogen) into heavier ones. The steady state universe supposes there to be some additional, unknown mechanism for creating new matter out of nothing, so that space and matter grow together and keep the ratio constant. --Amble (talk) 21:43, 29 October 2021 (UTC)[reply]

Insert picture of Fred Hoyle frantically waving his hands. Clarityfiend (talk) 22:28, 29 October 2021 (UTC) [reply]

Calculating sidereal time

I'm trying to calculate sidereal time by following chapter 12 in Astronomical Algorithms by Jean Meeus.

He gives example 12.a, mean sidereal time at Greenwich on April 10, 1987, at 0H UT. He gives two equations (in seconds):

theta₀ = 100.46061837 + 36000.770053608 * T + 0.000387933 * T² - T³ / 38711000.0 (Eq. 12.3)
theta₀ = 280.46061837 + 360.98564736629 * (JD - 2451545.0) + 0.000387933 * T² - T³ / 38710000.0 (Eq. 12.4)

He uses equation 12.2 and gets (rounded to the second)

theta₀ = 6 hours 41 minutes 50 seconds - 1099864 seconds.

I don't see how he gets these figures or where the 1099864 seconds comes from.

Then he says to add multiples of 86400 seconds (the number of seconds in a day) to get it in range, but he adds 23335.8 seconds and gets

13 hours 10 minutes 46 seconds.

My JD (Julian Date) and T (time in centuries from 1/1/2000) agree with his exactly:

JD = 2446895.5
T = -0.127296372347707

but I get:

theta₀ = -4482.306804892 (22 hours 45 min 18 sec) (by 12.3)
theta₀ = -1678122.30680491 (13 Hr 51 Min 18 sec) (by 12.4)

These are both far different from what he gets, and I don't know why. Am I missing something? Bubba73 ^{You talkin' to me?} 23:04, 29 October 2021 (UTC)[reply]

Your theta₀ values are correct -- but they are in degrees. Divide by 15 to get hours. --Amble (talk) 23:18, 29 October 2021 (UTC)[reply]

theta0 = (6 hours plus 41 minutes plus 50 seconds minus 1099864 seconds) = negative 12.something days, he added 13 days, not 23335.8 seconds. Sagittarian Milky Way (talk) 01:22, 30 October 2021 (UTC)[reply]

Thanks! All of these units in astrometry are driving me crazy!

Local time, universal time, sidearal time
most of the equations are in degrees, but they have to be converted to radians for the trig functions
Time is measured in seconds, hours, or centuries
angles are in degrees, hours, or radians. Bubba73 ^{You talkin' to me?} 02:16, 30 October 2021 (UTC)[reply]

I like to turn everything into Cartesian coordinates and work in matrix transformations. That way, you only ever need to handle the various spherical coordinate conventions on the way in and the way out. —Amble (talk) 03:16, 30 October 2021 (UTC)[reply]

I'm following the book by Meeus. That must have been how they did the calculations back in the day, even though the first edition was written in 1991. Some early computers didn't have floating point. Meeus has a lot of things in integers. Then he says "divide these by 1,000 and these by 1,000,000. Bubba73 ^{You talkin' to me?} 03:28, 30 October 2021 (UTC)[reply]

No floating point in 1991 is not surprising. Every time they say "x light years" or a planet orbit is x years they mean the Julius Caesar calendar. Sagittarian Milky Way (talk) 03:47, 30 October 2021 (UTC)[reply]

Even if some CPUs did not come with inbuilt floating point arithmetic, surely there were software libraries in 1991 implementing it. I find it hard to imagine a manufacturer marketing a CPU without a C compiler, in 1991 ANSI C. --Lambiam 12:28, 30 October 2021 (UTC)[reply]

The Sinclair Specrum (in 1982) had floating point capabilities and earlier computers certainly had, too. I recall using the Titan (1963 computer) in 1970, programmed in Fortran IV, and that language had had floating point for many years. Mike Turnbull (talk) 15:12, 30 October 2021 (UTC)[reply]

Did floating point have enough benefits for Jean Meeus to convert the book? Sagittarian Milky Way (talk) 15:51, 30 October 2021 (UTC)[reply]

In 1991 (or say the 1970s or 1980s when the recipes would have been written down) you could expect to have single precision floats. These recipes don’t just have the right offsets and coefficients, they also have the right precision in the right step. Trying to simplify it all with 32-but floats would get you simpler code and (usually) the wrong answer. —Amble (talk) 16:40, 30 October 2021 (UTC)[reply]

Intel 8087 (1980) implemented 64-bit (double-precision) float. DMacks (talk) 18:03, 30 October 2021 (UTC)[reply]

Local apparent solar time, local mean solar time, local civil time (AKA local mean solar time at the time zone's nominal longitude), Greenwich mean time (can be almost 1 second unaligned with Universal Time), Besselian New Year (10 degrees of Earth orbiting after the December solstice, not rounded, I don't know if this became obsolete with the switch from B1950.0 coordinates to J2000.0 (B for Besselian, J for Julian, even though it's New Year 2000 on the Gregorian calendar)), 2000.0 starts on January 1 noon but 1900.0 starts on January 0th noon ... Also 1 second of time is 15 seconds of arc, 4 seconds of time is 1 nautical mile (~6,080 feet) after multiplication by the cosine of the latitude, angle used to go signs (30 degrees), degrees, minutes, seconds, thirds and fourths, lunar months used to go 29 days (29), hours (12), and parts (793, 793 1080ths of an hour) and time used to go hours, minutes, seconds, thirds and fourths (AKA 5/18ths of a millisecond, imagine if high-tech astronomy said things like 54⁗ instead of 0.015"/15 milliarcseconds and camera shutter knobs were marked in thirds and fourths)... Sagittarian Milky Way (talk) 03:35, 30 October 2021 (UTC)[reply]

Well, I got my program to calculate the altitude and azimuth of the Moon working. But I could look that up - the reason for the program is to do reverse look-ups. (1) Given several locations, when will the Moon be near a specified altitude and azimuth, (2) from a certain location, when will the Moon rise south of a given azimuth, and possibly (3) given an altitude and azimuth, when and where do you have to be. Bubba73 ^{You talkin' to me?} 15:35, 3 November 2021 (UTC)[reply]

Sounds good! It might be interesting to add the phase of the moon to those search parameters. --Amble (talk) 16:09, 3 November 2021 (UTC)[reply]

The method to do that is in the book. I'll probably add it because one thing I'm interested in is days near the full moon. Bubba73 ^{You talkin' to me?} 00:39, 4 November 2021 (UTC)[reply]

a little background (skip this if you aren't interested) When there was a supermoon in November 2016, I got a tight photograph of it shining through the glass of a lighthouse. I was going to do a similar photo last month, but not as tight, and a day or two before the full moon to have more sunlight on the lighthouse. I was near where I was in 2016, and I had freedom to move around to line things up. But the Moon came up too far to the south! There was nowhere I could get in order for the Moon and the top of the lighthouse to line up. That's why I decided to write the program. Bubba73 ^{You talkin' to me?} 03:21, 4 November 2021 (UTC)[reply]

October 30

Analog to digital conversion process

I didn't understand the portion: Sampling in Analog to digital conversion process.

I read this sentence from here: To sample the input signal the switch connects the capacitor to the output of a buffer amplifier. The buffer amplifier charges or discharges the capacitor so that the voltage across the capacitor is practically equal, or proportional to, input voltage. In hold mode the switch disconnects the capacitor from the buffer. The capacitor is invariably discharged by its own leakage currents and useful load currents, which makes the circuit inherently volatile, but the loss of voltage (voltage drop) within a specified hold time remains within an acceptable error margin for all but the most demanding applications.

It mentioned "input signal" clearly, but it didn't mention term output signal anywhere in the paraphrase. It didn't even mention output signal is binary type. So how binary type here achieved ? Rizosome (talk) 04:36, 30 October 2021 (UTC)[reply]

The description you give is just for sampling. A sample of the input voltage appears on the capacitor. This then allows measurement of a constant value, rather than the time varying input. You could say that the output is the voltage of the capacitor. To convert to binary, you need the analog to digital converter. (perhaps you can compare the capacitor voltage, to a voltage ramp, and measure the time it is equal. ) Graeme Bartlett (talk) 11:15, 30 October 2021 (UTC)[reply]

To be more explicit, the process of transforming an analog input signal to a digital output signal is best understood as a two-step process. The amplitude of the input signal is a continuous function of continuous time to a continuous range of values. In the output signal, both the time domain and the range are discrete. Sampling only makes the time discrete and leaves the range continuous. Using R for a continuum and Z for a discretum, and "→" as is usual for the direction of a mapping from domain to range, we have:

input signal: R → R

sample: Z → R

output signal: Z → Z

Our article Sample and hold describes only the first step. --Lambiam 11:47, 30 October 2021 (UTC)[reply]

Can non lipid ointments diffuse into the skin?

Maybe there is an article about such non lipid ointments/creams/lotions/Colloids?

Thanks, 182.232.129.86 (talk) 05:54, 30 October 2021 (UTC)[reply]

Calling a substance an ointment suggests that its main ingredient is a lipid. Glycolic acid is used in skin-care products for its capability to penetrate skin. A non-lipid solvent that is known for its ability to penetrate the skin without damaging it is dimethyl sulfoxide (DMSO), which can be used for topical delivery of solutes. Its use has several hazards, some of which can be serious; see the section DMSO § Safety. Our article Absorption (skin) does not discuss any specific substances other than DMSO, and I did not find an article with a more general treatment of non-damaging skin penetrating substances. --Lambiam 11:23, 30 October 2021 (UTC)[reply]

Very many substances are toxic by skin absorption and this reference for acetonitrile is typical. Hence most lab chemists handling solvents wear appropriate gloves of nitrile rubber or other similar material. The OP's term "ointment" is, as Lambiam said, normally reserved for things that are intended to be rubbed on the skin, not necessarily to penetrate it, otherwise described as topical applications. Mike Turnbull (talk) 12:12, 30 October 2021 (UTC)[reply]

Drag on Satellites

To quote from an article in "New Scientist" ; "...a warming planet might ..reduce.. the drag on satellites, keeping them in orbit for longer." This seems to imply that as the atmosphere warms it causes less drag on orbiting satellites. I can't understand how this could be. Wouldn't the upper atmosphere reach further into space if it warmed up and expanded? And wouldn't this cause MORE drag on satellites in low earth orbit, bringing them down sooner? Any references or comments on this would be much appreciated!! 49.197.130.6 (talk) 07:01, 30 October 2021 (UTC)[reply]

A warmer atmosphere would presumably become less dense (unless additional atmospheric gases were released from the lithosphere and/or hydrosphere), and atmospheric material that expanded higher than the orbit in question would no longer exert a net gravitational attraction on a satellite in it; perhaps these would more than offset increased drag in some circumstances.

Can you cite the issue and/or date and page? I subscribe to New Scientist (in paper form) and would like to study the full passage in context. {The poster formerly known as 87.81.230.195} 90.200.65.29 (talk) 07:16, 30 October 2021 (UTC)[reply]

(OP) it's in the leader of the latest edition, 30 october 2021 49.197.130.6 (talk) 07:31, 30 October 2021 (UTC)[reply]

I'm having trouble finding the article (I only have an database subscription, can't easily browse a whole issue). But [6] is an explanation of an anomalous cooling in the upper atmosphere as a result of CO2 released at lower levels. The cooling causes contraction: pulling the atmosphere "down" a bit leaves it less dense (==less drag) up where the satellites are. DMacks (talk) 07:48, 30 October 2021 (UTC)[reply]

Ah, right! The New Scientist leader points to a Features article on pp 42-46, 'Space Jam' by Robin George Andrews, which I hadn't yet reached (my copy arrives no earlier than Friday).

The relevant passage (p 44) reads:

"One saving grace so far has been that space junk often gets dragged into the lower atmosphere and burns up. Unfortunately, as we have recently discovered, climate change means the rate at which this happens may decline, making orbital overcrowding worse.

In the upper atmosphere, the sun's extreme ultraviolet radiation splits molecular oxygen into two oxygen atoms that collide with carbon dioxide molecules, releasing infrared energy. Adding more carbon dioxide to the upper atmosphere increases this effect. As more infrared energy is released, it escapes into space and so the upper atmosphere cools. In this more frigid environment, the particles lose energy and the upper atmosphere contracts.

This phenomenon was predicted in 1989, and has been observed for some time. But [Hugh Lewis, a space debris expert at The University of Southampton, UK] and his colleagues recently realised it is influencing the lifetime of space junk. When falling orbital debris meets atmospheric particles, the object experiences drag. This causes the size of its orbit to shrink, bringing it closer to the denser, lower atmosphere in which it will eventually be incinerated. The climate change-induced contraction of the upper atmosphere will reduce the drag that debris experiences as it spirals towards us. This means it will stay in orbit for longer.

A recent paper, co-authored by Lewis, found that objects in low Earth orbit will stay up there for 30% longer even if we restrict carbon dioxide emissions to successfully keep the global average temperature rise to 1.5°C this century."

Hope this is useful. {The poster formerly known as 87.81.230.195} 90.200.65.29 (talk) 12:17, 30 October 2021 (UTC)[reply]

You compare Earth with Venus, which has CO2 atmosphere. Whereas Earth has a hot thermosphere with the temperature in excess of 1000K, at Venus the thermosphere is rather cool at 300-400 K during day and at about 100K at night. As a result the atmosphere of Venus is rather compact. Ruslik_Zero 20:18, 30 October 2021 (UTC)[reply]

Grinding plant-parts with oils

If we want to use certain natural products available in plants, a good way to do that is to grind relevant plant-parts (flowers/fruits/roots/seeds, etc.), often after drying them, with some oil.

Are some oils better at capturing the natural product out of the plant-part better than others?

For example, should "saturated" oils be better than "non saturated" oils and alike?

The purpose of the question is to understand if some oils are better than other for creating cosmetics grade / food grade essential oil products by means of fragrance/flavor/nutritional content.

Thanks, 182.232.129.86 (talk) 09:24, 30 October 2021 (UTC)[reply]

It is hard to discuss in generality – what is the nature of the "natural products available in plants" you want to "capture", and what is the purpose to which they will be put after extraction? The process of extraction by immersion in a liquid is known by the more technical name "maceration". If you want to extract essential oils, used for example in aromatherapy, this article on how essential oils are made contains a detailed description of extraction by maceration, but mentions, generically, using carrier oils as solvent. The absence of a discussion of which oils to use as carrier suggests that it does not make a big difference. This article states that commonly used solvents are olive oil and sunflower oil. Another carrier oil, advocated if the product is to be rubbed in the skin, is jojoba oil. --Lambiam 10:54, 30 October 2021 (UTC)[reply]

For interest, Shea butter is also used as an ointment base, as well as on its own. {The poster formerly known as 87.81.230.195} 90.200.65.29 (talk) 12:30, 30 October 2021 (UTC)[reply]

It is likely that vegetable oils are selected on the basis of their having little to no odor of their own, and not being too quick to go rancid. The color of the oil may also be important. Abductive (reasoning) 01:27, 31 October 2021 (UTC)[reply]

This recipe for chili oil says "High temperature oil can simulate the strong aroma while lower temperature oil brings us the bright red color". Alansplodge (talk) 12:51, 1 November 2021 (UTC)[reply]

October 31

If I mimic some person's voice, am I matching his frequency of sound wave or wavelength of sound wave?

If I mimic some person's voice, am I matching his frequency of sound wave or wavelength of sound wave? What exactly am I mimicking here in terms of a wave? Rizosome (talk) 03:59, 31 October 2021 (UTC)[reply]

The two are directly linked. wavelength (m)*frequency(Hz)=speed of sound(m/s). Greglocock (talk) 05:54, 31 October 2021 (UTC)[reply]

I am not asking the relation between wavelength and frequency. I am asking about physics behind vocal mimicry. Rizosome (talk) 05:59, 31 October 2021 (UTC)[reply]

OK, to put it another way, wavelength and frequency are inextricably linked (different ways of expressing the same thing), so the answer is, both.--Shantavira|^{feed me} 09:28, 31 October 2021 (UTC)[reply]

It's also unlikely that you would be precisely matching it. ←Baseball Bugs ^{What's up, Doc?} carrots→ 10:21, 31 October 2021 (UTC)[reply]

A human voice is far too complex to be reduced to a single sound wave. It is a complex mixture of sound waves, both fundamentals and harmonics created by the physical characteristics of that person's entire vocal tract and by resonances in their sinuses and other head and neck anatomy, plus the unique way they use their voice in terms of volume and pitch variations, speech rhythms and pauses, their idiosyncratic, social class and regional accents, and the register they consciously or unconsciously employ.

Just to allow an estimation on effort for any response: Have you got the basic answers to your recent question? --91.47.21.246 (talk) 15:22, 31 October 2021 (UTC)[reply]

And many others before that. Rizo almost never follows up. ←Baseball Bugs ^{What's up, Doc?} carrots→ 00:30, 1 November 2021 (UTC)[reply]

See also the article Spectrogram. The spectrogram of a person speaking is also called a voiceprint. They are used in speaker recognition, but also in forensic analysis much like fingerprints.^[7][8][9] If someone can produce intelligible speech while matching another person's voiceprint, the timbre of their voice will sound like that other person's. --Lambiam 20:50, 31 October 2021 (UTC)[reply]

Baseball Bugs I am following every response to my questions. This is the line I am waiting for: If someone can produce intelligible speech while matching another person's voiceprint, the timbre of their voice will sound like that other person's. Rizosome (talk) 04:26, 1 November 2021 (UTC)[reply]

I didn't say "follow", I said "follow up". It would be nice if, once you get an answer, you could follow up by saying something, such as "I understand" or "Thank you." ←Baseball Bugs ^{What's up, Doc?} carrots→ 04:34, 1 November 2021 (UTC)[reply]

Yes, in order for me to speak in such a way that I can be mistaken for you, I must match your timbre. Whether I can do that is much more complex than matching pitch (frequency/wavelength), which normally fluctuates within every sentence. —Tamfang (talk) 02:55, 2 November 2021 (UTC)[reply]

November 1

Berberine for diarrhea

This involves the following two discussions:

Do the sources listed in the above discussions support a claim that Berberine is an effective treatment for diarrhea? My conclusion is that the sources supporting that claim do not meet the requirements of WP:MEDRS. Am I correct? --Guy Macon (talk) 04:43, 1 November 2021 (UTC)[reply]

If the issue is the interpretation of WP:MEDRS, then the talk page of that guideline may be a better place for a discussion. Just refer to the specific sources support the claim; the prior discussions seem to be more about the appropriateness of the guideline rather than its interpretation, and so are not particularly relevant. --Lambiam 09:37, 2 November 2021 (UTC)[reply]

Can activated carbon destroy acetic acid?

I want to thicken distilled vinegar (so to make a vinegar paste), with activated carbon.

Can activated carbon destroy/sabotage the vinegar's acetic acid molecules (or, at least, is activated carbon a chemical base)?

Thanks, 182.232.42.121 (talk) 12:36, 1 November 2021 (UTC)[reply]

We had another IP user wanting to thicken vinegar, with answers here. I have no idea why you would use activated charcoal but it will be inert to the vinegar, being neither an acid nor a base itself. Mike Turnbull (talk) 14:54, 1 November 2021 (UTC)[reply]

I think that this other question from me as a person and not as an IP :) isn't related. I thought that activated carbon may have medicinal properties and is worth checking. I found activated carbon as a wonderful vinegar thickner, actually the smoothest and least residual I have tried, but it can be very "messy" to work with due to color stains. 2001:44C8:42CD:E478:AC74:4933:5B45:8BAB (talk) 04:05, 3 November 2021 (UTC)[reply]

Solar radius instead of diameter

Why solar radius rather than solar diameter has been chosen as standard? One can assume that diameter gives a better idea of the star's size, whereas radius gives only half of the value. Thanks. 212.180.235.46 (talk) 15:18, 1 November 2021 (UTC)[reply]

By convention, spheres are defined by their radius; as one convenient definition of a sphere is every point in three dimensions located a distance, r, away from a single point. That distance, r, is the radius, and needs to be manipulated by multiplying it by 2 to get the diameter. Since 1) It is entirely arbitrary whether to use the radius or the diameter and 2) we already have definitions that use radius, it seems perfectly fine to use the radius. All other measures (surface area, volume, etc.) can also be defined from r. They could be defined from d too, but it isn't any easier or harder to do so, so we stick with one measurement (radius) instead of 2 (radius for some measures, and diameter for others). --Jayron 32 15:22, 1 November 2021 (UTC)[reply]

The NASA ephemeris gives angular size in diameter not radius and not everyone knows that 2pi is tau, it's not radius always. I suppose using r but pi makes these more elegant than the other 3 conventions: .5τr² πr² τ/8d² π/4d² • 2τr² 4πr² .5τd² πd² • .6τr³ 4/3πr³ 1/12τd³ 1/6πd³. Sagittarian Milky Way (talk) 19:52, 1 November 2021 (UTC)[reply]

Yes, angular size is in diameter, and most people understand how to multiply or divide by 2. It's not difficult math. --Jayron 32 11:22, 2 November 2021 (UTC)[reply]

Yes it doesn't matter which one gets the name. I was mentioning that it was circumference over diameter that got the famous Greek letter for some reason (I'm not sure why) and not circumference over radius which would be more "pure". Sagittarian Milky Way (talk) 17:09, 2 November 2021 (UTC)[reply]

The conversion is pretty easy: if the radius of a star is 3 solar radii, then the diameter of that star is 3 solar diameters. --Amble (talk) 18:23, 1 November 2021 (UTC)[reply]

November 2

What's the term for prioritys.

What do you call this kind of situation: if something is both C and B, we call it C. If something is both B and A, we call it B. And so forth. I know this is a heavily CS question, but I know we have this in science, especially organic chemistry. For example, if a compound is both an alcohol and an amine, we call it an alcohol, but if something is both an alcohol and an amide, we call it an amide. So, some kind of precedence. What do we call this in CS, and, what do we call this in science? 67.165.185.178 (talk) 23:25, 2 November 2021 (UTC).[reply]

I remember asking a pharmacology scientist, if something is both an anti-biotic, and an anti-viral, what do we call it? He didn't know there was a thing, or a special word that emphasized both. 67.165.185.178 (talk) 23:27, 2 November 2021 (UTC).[reply]

How about "antiseptic"? ←Baseball Bugs ^{What's up, Doc?} carrots→ 01:42, 3 November 2021 (UTC)[reply]

I'm not sure there is a general rule stating that a compound that is both an alcohol and an amine should preferentially be referred to as an amine. An example is 2-aminoethan-1-ol, for which the infobox in our article lists a dazzling array of names, including β-aminoethyl alcohol. The suffix "-ol" in the preferred IUPAC name classifies it as an alcohol; the hydroxyl group is considered the functional group with the highest priority. In general, I think "priority" is a good term for indicating which one of a choice of two candidates is to be preferred; for a choice among a larger group, "highest priority" is more explicit. I can't think of a good situation where two names are equally appropriate, given their definitions, but where one conventionally takes priority. A cat is both a pet and a predator; whether we refer to Molly as a pet or as a predator depends on the context. Sometimes both are appropriate.^[10][11][12] --Lambiam 11:42, 3 November 2021 (UTC)[reply]

Sigh. Here's the priority, straight from my organic chemistry textbook. ~~And I properly indented your comment~~. Carboxylic acid > ester > amide > nitrile > aldehyde > ketone > alcohol > amine > alkene > alkyne > alkane > ether > halides. 67.165.185.178 (talk) 12:55, 3 November 2021 (UTC).[reply]

My contribution was properly indented, because it was solely in response to the original question and had nothing to do with names for substances that are both antibiotic and antiviral. --Lambiam 17:10, 3 November 2021 (UTC)}[reply]

I think that the term the OP seeks is a classification and that article gives a lot of the background. In organic chemistry the series quoted is that established by Friedrich Konrad Beilstein in the 19th century and now implemented in the Beilstein database and elsewhere.^[1] The history of science is full of attempts to classify things. For example, the periodic table was developed when it was realised that classifying elements by their atomic number (rather than, say, their atomic weight) was useful. Such classification is a human construct: the appropriate classification depends on context — so, for example Beilstein's system does not include inorganic compounds and in some respects is not "logical". Any such systematic approach gains traction because it is useful and widely applicable. Mike Turnbull (talk) 14:12, 3 November 2021 (UTC)[reply]

Is the OP referring to the Cahn–Ingold–Prelog priority rules? That's only used in a specific application, though... --Jayron 32 16:31, 3 November 2021 (UTC)[reply]

References

^ Luckenbach, Reiner (1 May 1981). "The Beilstein Handbook of Organic Chemistry: the first hundred years". J. Chem. Inf. Comput. Sci. doi:10.1021/ci00030a006.

terminology about luminescence and fluorescence

I'm curious to know if biologists, chemists, and physicists have different words for the same thing? I wonder if physicists have their own word for what chemists call chemiluminescence and fluorescence. Like, what do physicists call the concept behind glow-in-the-dark toys? If inorganic semiconductors do fluorescence, we all call them quantum dots. 67.165.185.178 (talk) 14:27, 3 November 2021 (UTC).[reply]

Not as far as I know. There are two different physical processes that can lead to luminescence known as fluorescence and phosphorescence, which are different processes, and not two different names from different fields. It should also be noted that chemiluminescence is yet another different process. AFAIK, there are not different terms in use among different fields for these processes. --Jayron 32 15:52, 3 November 2021 (UTC)[reply]

Sometimes you'll see things just called "luminescence spectra" as a catchall term, but I've seen that from chemists, biologists, and physicists. If they don't want to get into specific details like intersystem crossing of electronic states and spins, lifetime effects, etc., it can often be OK to just use "luminescence." An example would be an more simple analytical application that just makes use of the wavelength and intensity of the luminescence, but doesn't necessarily care about the specific electronics of the system undergoing transitions. --OuroborosCobra (talk) 16:22, 3 November 2021 (UTC)[reply]

Also, as the OP mentioned quantum dots, it should be noted that this is also a distinct phenomenon on its own, and not a synonym for luminescence used by one branch of science. --Jayron 32 16:29, 3 November 2021 (UTC)[reply]

Afaik, quantum dots is simply something that absorbs UV and emits light, but only when that something is an inorganic semiconductor, possibly set at a small but defined length. And now, they're inventing ways to make quantum dots absorb IR, and still emit light, which is now anti-Stokes shifts. 67.165.185.178 (talk) 00:17, 4 November 2021 (UTC).[reply]

In biology, it's bioluminescence. -- 107.15.157.44 (talk) 08:06, 4 November 2021 (UTC)[reply]

November 4

Potentiometer and Zener diode are interchangeable in eletrical circuits?

I discovered that both are somewhat voltage regulators. So those two are interchangeable? Rizosome (talk) 02:09, 4 November 2021 (UTC)[reply]

Was stealth technology for US airplanes based upon on previous technology?

Something I was discussing in the bar tonight. Someone was talking about the Roswell crash and how a bunch of new technology for the US air force came from that.

Apparently the stealth material for fuselage of the planes as used by the USAF just appeared out of nowhere, not based on any previous research? Is that right? And the Russians/Soviets were trying to replicate it and failed until a US stealth bomber was shot down in the Bosnian war and the FSB took samples of the wreckage back to Moscow to be reverse engineered?

Not trying to conspiritard. Just looking for more info. I find it interesting. 146.200.107.70 (talk) 02:24, 4 November 2021 (UTC)[reply]

The idea of radiation-absorbent material predates the alleged 1947 Roswell incident. Those pesky Nazis were doing research in World War II. German submarine U-480 had a special rubber coating to try to defeat sonar. Reimar Horten, one of the designers of the Horten Ho 229 flying wing, claimed he intended to add radar-absorbent material to its surface. Clarityfiend (talk) 03:47, 4 November 2021 (UTC)[reply]

See also the history section in the Stealth technology article. -- 107.15.157.44 (talk) 04:56, 4 November 2021 (UTC)[reply]

It's a blindingly obvious development after radar was invented. No need to involve extraterrestrials. Now if you were to suggest a certain ex-POTUS obtained alien mind-bending technology to use on his endless rallies ... Clarityfiend (talk) 05:36, 4 November 2021 (UTC)[reply]

[1] Walker, Timothy (6 October 2020). Pollination: The Enduring Relationship Between Plant and Pollinator. Princeton University Press. pp. 1–224. ISBN 9780691203751.

[USAtoday_20201122-2] Hauck G, Gellis K (November 22, 2020). "We're celebrating Thanksgiving amid a pandemic. Here's how we did it in 1918 – and what happened next". USA Today. Archived from the original on November 21, 2020.

[3] Luckenbach, Reiner (1 May 1981). "The Beilstein Handbook of Organic Chemistry: the first hundred years". J. Chem. Inf. Comput. Sci. doi:10.1021/ci00030a006.

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