Wikipedia:Reference desk/Science: Difference between revisions

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I’ve just read that [[ciguatoxin]]s produced by ”[[Gambierdiscus toxicus]]” are largely harmless for larger species in food chain, even after [[biomagnification]], and that they harm mostly warm-blooded animals, including humans. That looks odd because evolutionarily one would expect toxins to target direct threats which isn’t the case here. That contrasts, for example, with [[capsaicin]] that evolved as a protection against pepper-eating animals. Is there an explanation? [[User:Brandmeister|<span style=”font-family:Impact; font-size:100%; color:#E0E0E0; font-weight:400; letter-spacing:1px; text-shadow: 0 0 3px #000, 1px 1px 2px #000, 2px 2px 3px #222, 3px 3px 4px #000;”>Brandmeister</span>]] <sup>[[User talk:Brandmeister|talk]]</sup> 22:06, 30 November 2025 (UTC)

:”G. toxicus” may have evolved to produce ciguatoxins both for protection against being grazed by herbivorous fish, and also for some other metabolic reason, either as a necessary byproduct or for some function as yet undiscovered. The fish, meanwhile, may have then evolved immunity to the ciguatoxins (see Red Queen‘s ~~race~~). That a relative few these fish may then be eaten by larger animals (including us) and those might also then be poisoned, is outside the evolutionary context of the dinoflagellate, so it’s just our bad luck.

:”G. toxicus” may have evolved to produce ciguatoxins both for protection against being grazed by herbivorous fish, and also for some other metabolic reason, either as a necessary byproduct or for some function as yet undiscovered. The fish, meanwhile, may have then evolved immunity to the ciguatoxins (see Red Queen ). That a relative few these fish may then be eaten by larger animals (including us) and those might also then be poisoned, is outside the evolutionary context of the dinoflagellate, so it’s just our bad luck.

:[https://www.sciencedirect.com/topics/agricultural-and-biological-sciences/dinoflagellate#:~:text=As%20photosynthetic%20organisms%2C%20dinoflagellates%20contribute,wide%20range%20of%20marine%20animals. This paper] discusses the general context of dinoflagellate toxin production, although it doesn’t mention ciguatoxin specifically. {The poster formerly known as 87.81.230.195} [[Special:Contributions/~2025-31359-08|~2025-31359-08]] ([[User talk:~2025-31359-08|talk]]) 06:05, 1 December 2025 (UTC)

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The article says human physicists are making quark gluon plasma at CERN now. That’s great but isn’t the equivalent substance early in the Big Bang probably subjected to strong gravity, strong and complicated magnetic fields, and strong and complex angular momentum that would bring in more relativistic effects that the substance doesn’t experience at CERN?Rich (talk) 01:40, 18 November 2025 (UTC)[reply]

I gotta ask. What are the non-human physicists doing? Clarityfiend (talk) 04:15, 18 November 2025 (UTC)[reply]

I was warned not to say, unless I want to breathe vacuum.Rich (talk) 06:58, 18 November 2025 (UTC)[reply]

That is probably the case, but we have to start somewhere. Actually creating quark soup at all and observing its physical properties are steps forward, necessary before we can begin to figure out the significance of those other factors in the Big Bang (even assuming that’s possible). {The poster formerly known as 87.81.230.195} ~2025-31359-08 (talk) 19:45, 18 November 2025 (UTC)[reply]

Morning folks!! I was wondering if anybody knows what “healing by organisation” means in its context in 1960-1870. This is specifically for the Joseph Lister article which I’m writing. Its long I know. It will be split. I’m confused about this term. It seems to be healing by organisation in blood clots and relates to an address that Lister gave in “An Address on the Antiseptic System of Treatment in Surgery, delivered before the Medico-Chirurgical Society of Glasgow” on 17 April 1868. As a surgeon there is discussions about wound healing. I’ve discovered healing by “First Intention” means but not by healing by organisation. Would any medical historians have any idea?

According to ChatGPT:

“Healing by organization” is an archaic medical term used in 19th–early-20th-century pathology and surgery.

It referred to:

Definition

Healing by organization meant that damaged tissue was repaired not by regeneration of the original tissue, but by the ingrowth of granulation tissue that later matured into fibrous (scar) tissue.

In other words, the body “organized” the injury by filling it with connective tissue.

Modern terminology

Today this process is simply called:

Fibrous (scar) formation

Healing by fibrosis

Granulation tissue formation and maturation

Secondary intention healing (when referring to open wounds that must fill in from the bottom)

Historical context

Before modern histology and wound-healing science, “organization” described how:

A blood clot or inflammatory exudate becomes infiltrated by fibroblasts and capillaries.

This tissue gradually becomes dense collagenous scar tissue. ~2025-34800-71 (talk) 09:04, 19 November 2025 (UTC)[reply]

@~2025-34800-71: I know what is now, which I didn’t before, but I need proper references for the definition, so I can check the book reference. scope_creep^Talk 19:57, 19 November 2025 (UTC)[reply]

Here you find a discussion of what Lister meant by the term. It appears that the term has not fallen into complete disuse: [1], [2], [3]. ‑‑Lambiam 23:21, 19 November 2025 (UTC)[reply]

Thanks @Lambiam: I don’t know how I didn’t see that last night. I must have been conked out when I was searching; on automatic. Thanks folks. scope_creep^Talk 23:45, 19 November 2025 (UTC)[reply]

Is this guy (found in New England) an Agelenidae coras? If so, what species? Jay Cubby 14:33, 19 November 2025 (UTC)[reply]

Assuming the specimen is in the genus Coras, it may be hard to identify the species from these images, because the visual differences between different species may be subtle and not displayed in these images. Case in point: the caption for the first image in our article on the genus Coras has: “Coras species, probably C. medicinalis“. Is the specimen even in this genus? If so, their anterior median eyes are larger than their anterior lateral eyes, but I doubt even this can be discerned from the available images. ‑‑Lambiam 10:23, 20 November 2025 (UTC)[reply]

From neutron star:

Neutron star material is remarkably dense: a normal-sized matchbox containing neutron-star material would have a weight of approximately 3 billion tonnes, the same weight as a 0.5-cubic-kilometer chunk of the Earth (a cube with edges of about 800 meters) from Earth’s surface.

Neutron stars are extremely dense, to be sure, but what would that matchbox weigh on Earth? What is its mass? Tonnes are a mass measurement, not a weight measurement, so I don’t know if this badly written passage means that it has a mass of approximately 3 billion tonnes or if it means that its weight on the neutron star is the same as the weight of a 3-billion-tonne object on Earth. First sounds reasonable because the star is very dense; second sounds reasonable because the star is very massive and has a tiny radius, so per gravitational constant, an extremely massive object with an extremely small radius of distance will cause any object on its surface to be extremely heavy. The statement has two citations, but I don’t see the statement’s information in either of them. Nyttend (talk) 09:52, 26 November 2025 (UTC)[reply]

It might be better to replace the word “weight” by “mass”; I assume the writer thought that lay readers were more familiar with weight than with mass. With weight expressed in mass units, the statement is actually true both on the neutron star and on earth; that would not be the case if the weight was properly given in Newtons, i.e. as a force. —Wrongfilter (talk) 11:15, 26 November 2025 (UTC)[reply]

Neutron Newtons? ←Baseball Bugs ^{What’s up, Doc?} carrots→ 12:26, 26 November 2025 (UTC)[reply]

Not as tasty as the fig ones. —User:Khajidha (talk) (contributions) 13:39, 26 November 2025 (UTC)[reply]

Filling, though. 🙂 ←Baseball Bugs ^{What’s up, Doc?} carrots→ 14:03, 26 November 2025 (UTC)[reply]

Makes me feel weighted down and sluggish every time I eat them. —User:Khajidha (talk) (contributions) 14:22, 26 November 2025 (UTC)[reply]

What is the normal size of a matchbox, anyway? I would assume it varies by market. Better to use a cm3. —Tamfang (talk) 22:20, 26 November 2025 (UTC)[reply]

Maybe about the size of a Jimmy Neutron Matchbox car? — Preceding unsigned comment added by Baseball Bugs (talk • contribs) 00:28, 27 November 2025 (UTC)[reply]

I’ve left a related question at WP:RDH. Nyttend (talk) 04:06, 27 November 2025 (UTC)[reply]

I’m looking for someplace to redirect perfluoroalkylether (PFAE) and perfluoropolyalkylether (PFPAE). Are these the same as perfluoropolyether (PFPE)? Or are there better targets? Should I just start stubs? — Beland (talk) 02:39, 29 November 2025 (UTC)[reply]

PFAE ans PFPAE are mentioned in our article Krytox as being synonymous with PFPE. Industrial and commercial websites agree: [4], [5], [6], [7], [8]. ‑‑Lambiam 15:24, 29 November 2025 (UTC)[reply]

Redirects added; thanks for the sourcing! — Beland (talk) 17:23, 29 November 2025 (UTC)[reply]

In night I see all stars of same white colour but one star is yellower than others. It twinkles like other stars but I am suspect it is some planet. ~2025-37195-37 (talk) 08:12, 30 November 2025 (UTC)[reply]

Where is it? Which constellation? There are many colored stars, but the colors are mostly not visible to the naked eye. See Stellar_classification#Harvard_spectral_classification for colors. However, there is a rule of thumb that if it twinkles, it is not a planet (because of the partial polarization of reflected light). Shantavira|^{feed me} 09:29, 30 November 2025 (UTC)[reply]

Polarisation has nothing to do with it — the reason why planets twinkle less than stars is that they have much larger angular sizes. The main planet in the evening sky at the moment is Saturn but it is not very conspicuous, as there are many stars of similar brightness. Later in the evening Jupiter rises but that doesn’t strike me as particularly yellow, so without further information I guess the OPs question cannot be answered. —Wrongfilter (talk) 10:49, 30 November 2025 (UTC)[reply]

There are a bunch of apps for your phone that you can point at the sky and they’ll tell you what you’re looking at. Abductive (reasoning) 11:18, 30 November 2025 (UTC)[reply]

If it’s properly dark and you’ve got good eyesight, some bright stars are noticeably coloured. For example, Betelgeuse (the right shoulder of Orion, which you see on the left if you’re on the Northern hemisphere) is noticeably red and Bellatrix (Orion’s other shoulder) is blue. I suggest you use some planetarium program to find which star appears yellow to you. Stellarium is free and open source.

The most obviously coloured object in the sky is Mars, but that currently appears so close to the Sun that it’s practically invisible. PiusImpavidus (talk) 11:13, 30 November 2025 (UTC)[reply]

Since we don’t know whether you are in the North or South hemisphere, it’s impossible to tell what stars are currently visible to you at night. It should not be too difficult for you to find out which constellation the star in question is in. (My guess would be Capella.) {The poster formerly known as 87.81.230.195} ~2025-31359-08 (talk) 21:50, 30 November 2025 (UTC)[reply]

What would be the map projection of a true-perspective drawing of a globe, like these? I was thinking maybe just “globular projection”, but that would seem too vague, since it can also describe things like the Nicolosi globular projection. ~2025-31275-58 (talk) 10:44, 30 November 2025 (UTC)[reply]

That should be a simple Orthographic map projection. —Wrongfilter (talk) 10:55, 30 November 2025 (UTC)[reply]

Please see Wikipedia:Reference desk/Humanities#Audio recording of a Quagga. Andy Mabbett (Pigsonthewing); Talk to Andy; Andy’s edits 14:12, 30 November 2025 (UTC)[reply]

I’ve just read that ciguatoxins produced by Gambierdiscus toxicus are largely harmless for larger species in food chain, even after biomagnification, and that they harm mostly warm-blooded animals, including humans. That looks odd because evolutionarily one would expect toxins to target direct threats which isn’t the case here. That contrasts, for example, with capsaicin that evolved as a protection against pepper-eating animals. Is there an explanation? Brandmeister ^talk 22:06, 30 November 2025 (UTC)[reply]

G. toxicus may have evolved to produce ciguatoxins both for protection against being grazed by herbivorous fish, and also for some other metabolic reason, either as a necessary byproduct or for some function as yet undiscovered. The fish, meanwhile, may have then evolved immunity to the ciguatoxins (see Red Queen hypothesis). That a relative few these fish may then be eaten by larger animals (including us) and those might also then be poisoned, is outside the evolutionary context of the dinoflagellate, so it’s just our bad luck.

This paper discusses the general context of dinoflagellate toxin production, although it doesn’t mention ciguatoxin specifically. {The poster formerly known as 87.81.230.195} ~2025-31359-08 (talk) 06:05, 1 December 2025 (UTC)[reply]

I can’t find an explanation for the SI unit “ $W s r − 1 m − 2 n m − 1 {\displaystyle Wsr^{-1}m^{-2}nm^{-1}} <img decoding="async" src="https://wikimedia.org/api/rest_v1/media/math/render/svg/57ef62530abc4314e31a40c6feeb2ef9032cbeed" aria-hidden="true" alt="{\displaystyle Wsr^{-1}m^{-2}nm^{-1}}" width="7340.2" height="1152.1">$ “.
In some articles I find “ $W s r − 1 m − 3 {\displaystyle Wsr^{-1}m^{-3}} <img decoding="async" src="https://wikimedia.org/api/rest_v1/media/math/render/svg/496a7db96f69297d315de38aa0cb4d7d857bfb5e" aria-hidden="true" alt="{\displaystyle Wsr^{-1}m^{-3}}" width="4856.8" height="1152.1">$ “,
or “the power radiated per unit wavelength interval at wavelength 𝜆 by unit area of blackbody at temperature T”,
or “The spectral radiance is defined as the radiant energy per unit of time emitted within a unit spectral bandwidth from a unit area of surface into a solid angle in a direction normal to the surface”.
I find also this text:”the power from wavelength 𝜆 to 𝛥𝜆”, but after no trace of 𝛥𝜆 in the formulas ???
I assume that “ $n m − 1 {\displaystyle nm^{-1}} <img decoding="async" src="https://wikimedia.org/api/rest_v1/media/math/render/svg/d365fdf4834eea92d4c9fbafa8d14447b0f9f18a" aria-hidden="true" alt="{\displaystyle nm^{-1}}" width="2483.4" height="1152.1">$ ” is to match a bandwidth unit of 1 nanometer, but I don’t know how to interpret it as there is no bandwidth parameter in the law.
So where can I find an official reference for the SI units of Planck’s law ?
PS: In wikipedia I get the SI units but without explanation nor reference, and I was not lukky with Google ! Malypaet (talk) 23:24, 30 November 2025 (UTC)[reply]

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