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September 5

How much of Speed of light can be decreased until Universe go unstable?

I feel stability of universe also depends on speed of light. So how much of Speed of light can be decreased until Universe go unstable? Rizosome (talk) 02:56, 5 September 2021 (UTC)[reply]

Where did you get this idea from? Also note that the speed of light varies depending on what it's traveling through. ←Baseball Bugs ^{What's up, Doc?} carrots→ 04:23, 5 September 2021 (UTC)[reply]

The metre is defined in the International System of Units (SI) as the distance travelled by light in vacuum in 1/299792458th of a second. It follows that the speed of light is exactly 299792458 metres per second. If it goes down, this means that reciprocals have become unstable. --Lambiam 06:24, 5 September 2021 (UTC)[reply]

That's not a fact about the speed of light; it's a fact about how the meter is defined in SI. I think we have an article called variable speed of light; I haven't looked at it recently and don't know what it currently discusses, but you can't answer the question "what if the speed of light were lower" by talking about a particular system of units. (It would certainly be fair to ask the questioner what is meant.) --Trovatore (talk) 16:19, 5 September 2021 (UTC)[reply]

Let's not some of us lose sight of the fact that the value c, colloquially referred to as "the speed of light," is a fundamental physical constant (we think) which light or other massless entities in a vacuuum necessarily must travel at, but that's an imposition on light by the universe, not something imposed on the universe by light. That light or other massless things travel at different velocities when not in a vacuum has no relevance to questions like Rhizome's.

As to that question, our article Fine-tuned universe may be of interest, as might Fine-tuning. {The poster formerly known as 87.81.230.195} 2.122.0.2 (talk) 19:36, 5 September 2021 (UTC)[reply]

Please read the section Variable speed of light § Dimensionless and dimensionful quantities, and note this quote:

At first we might be tempted to think that a world in which the speed of light was slower would be a different world. But this would be a mistake. If c, h, and e were all changed so that the values they have in metric (or any other) units were different when we looked them up in our tables of physical constants, but the value of α remained the same, this new world would be observationally indistinguishable from our world. The only thing that counts in the definition of worlds are the values of the dimensionless constants of Nature.

--Lambiam 21:56, 5 September 2021 (UTC)[reply]

But what if c alone were different, such that the value of α was also different? (I am asking on behalf of Rhizome, of course.) {The poster formerly known as 87.81.230.195} 90.209.121.112 (talk) 04:25, 6 September 2021 (UTC)[reply]

There is a shallow discussion at Fine-structure constant § Anthropic explanation, although I wonder if the presentation correctly reflects the cited source. --Lambiam 07:26, 6 September 2021 (UTC)[reply]

Production of Chloroquine and Hydroxychloroquine

How are chloroquine and hydroxychloroquine produced by the pharmaceutical companies? Are they made semi-synthetically from the bark of the cinchona tree? Our articles on those medicines don't seem to say how they are manufactured or produced? (Maybe our articles should be expanded to include that information, as described in reliable sources, but this is the Reference Desk, not a content form.)

I am not asking whether they have value in treating or preventing covid. We know that they do not. I am only asking how these medicines are produced. Robert McClenon (talk) 21:07, 5 September 2021 (UTC)[reply]

In organic chemistry, you learn reactions are made through a series of steps involving SN2, SN1, E2, and E1. The trick is to know what the starting materials are. (I.e., fusing 2 benzene rings into 1.). Then, there's selecticity, i.e., adding a substituent in the ortho-, meta-, or para- position. 67.165.185.178 (talk) 03:32, 6 September 2021 (UTC).[reply]

The original source from cinchona was severely limited in World War II, when these compounds were first in demand as anti-malarials. Hence purely synthetic routes were developed. Articles from the time include this report from 1949 and this thesis. I'm not sure how large-scale manufacture takes place today and it is a shortcoming of the Wikipedia articles that this aspect is not covered. Mike Turnbull (talk) 11:13, 6 September 2021 (UTC)[reply]

I've now updated the chloroquine and hydroxychloroquine articles to add the chemistry in their history sections. Mike Turnbull (talk) 13:58, 7 September 2021 (UTC)[reply]

Chloroquine is a de novo synthesis; cinchona bark was never in the mix. You can reliably source possible syntheses but I don't think you could reliably source manufacturing process(es). UNIDO for example had to interpolate in 1985 ("step-by-step technical and economic details were not always available...") [1], and the ACS article above illustrates how a bench synthesis may have to be "translated" to manufacturing; that's the sort of detail I'd be surprised to see published. "Synthesis of Essential Drugs" [2] has more detail on synthesis but probably fails WP:NOTTEXTBOOK. Yappy2bhere (talk) 21:45, 8 September 2021 (UTC)[reply]

Per MOS:CHEM It is our tradition to cite the first preparation of a compound. Most if not all commercially significant compounds are made by routes that are confidential to their manufacturers and may change according to the scale at which they are carried out. As Yappy2bhere said, many Wikipedia articles don't cover that. For chloroquine and hydroxychloroquine I added the routes from the 1940s which use 4,7-dichloroquinoline as an intermediate and I've now also written an article for that intermediate. My previous comment that The original source from cinchona was severely limited in World War II referred to using quinine directly as an antimalarial, not as a chemical intermediate: apologies for any confusion. Mike Turnbull (talk) 11:38, 9 September 2021 (UTC)[reply]

Production of Ivermectin

How is ivermectin produced by the pharmaceutical companies? Is it produced by extraction and processing from the product of certain bacteria? (If so, are the bacteria soil scavengers that are producing the vermicides in order to compete with worms in scavenging the soil?) Our article sort of implies that, but only sort of implies that. (Maybe it should be expanded, but this is the Reference Desk.)

I am not asking whether ivermectin has value in treating or preventing covid. We that it does not. I am interested in the origin of the nonsense belief. Robert McClenon (talk) 21:07, 5 September 2021 (UTC)[reply]

Regardless of how ivermectin is produced – which IMO is irrelevant to the origin of (incorrect) stories about the presumed efficacy of ivermectin in treating COVID-19 – there is a rational basis for its consideration. In a controlled in vitro study, a 5000-fold reduction in viral RNA after exposure to ivermectin compared with control was found in cells infected with the SARS-CoV-2 virus.^[3] Unfortunately, this did not translate to good results in clinical trials.^[4][5] --Lambiam 21:46, 5 September 2021 (UTC)[reply]

Yes, according to the 1983 source and 2017 "Ivermectin – Old Drug, New Tricks?": it's a purified product treated by reaction with hydrogen (hydrogenation). I can't find an explicit statement of why the bacteria make it, but it seems likely. Blythwood (talk) 00:25, 6 September 2021 (UTC)[reply]

Infinite-fold virus reduction is easy, just eat ivermectin until dead and if that fails dissolve body in acid until nothing left. Sagittarian Milky Way (talk) 00:47, 6 September 2021 (UTC)[reply]

That approach works in a sense, but it's close kin to throwing the baby out with the bathwater. ←Baseball Bugs ^{What's up, Doc?} carrots→ 03:41, 6 September 2021 (UTC)[reply]

[6] [7] also seem to confirm. Nil Einne (talk) 09:21, 6 September 2021 (UTC)[reply]

To answer your question, Robert McClenon, Ivermectin#Chemistry describes the production process. The bacterium is Streptomyces avermitilis and it produces avermectins, as described in this book chapter. As with other pharmaceutical products, the strain of S. avermitilis used in production now will have been considerably optimised for yield. The avermectins were mainly developed as commercial insecticides. Ivermectin is a synthetic derivative in which one of the double bonds is reduced by hydrogenation and this is the compound mixture marketed as an antiparasitic agent for human use. Your suggestion that the bacterium gains a competitive advantage by poisoning other soil organisms is plausible but I don't think that this has been established. Mike Turnbull (talk) 10:44, 6 September 2021 (UTC)[reply]

September 6

Covid PCR Test

Once you've taken a sample from your tonsils and nostril for a PCR test, is there a limit on the amount of time available to actually test the sample before the test will no longer give valid results? I submitted a test in the post and just wondered what happens if there are delays along the way. Thanks. 88.111.85.155 (talk) 12:37, 6 September 2021 (UTC)[reply]

Extended storage of SARS-CoV-2 nasopharyngeal swabs does not negatively impact results of molecular-based testing across three clinical platforms says: "This study demonstrates that nasopharyngeal swab specimens can be stored under refrigeration or even ambient conditions for 21 days without clinically impacting the results of the real-time reverse transcriptase-PCR testing". Alansplodge (talk) 12:54, 6 September 2021 (UTC)[reply]

BTW, "severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)" is the name of the virus that causes COVID-19 019)-and-the-virus-that-causes-it Naming the coronavirus disease (COVID-19) and the virus that causes it (WHO) Alansplodge (talk) 12:57, 6 September 2021 (UTC)[reply]

Why is there no way to INCREASE energy harvest in the gut?

There are many ways to reduce energy harvest from food. There's gastric bypass surgery; there are enzyme inhibitors like orlistat and acarbose, which reduce absorption of calories from fat and starch; there are even drugs like dapagliflozin, which increase excretion of carbohydrate calories in the urine. There's even a stomach pumping machine that literally sucks food out of your stomach just after you've eaten it. There are also nutrients like fiber and calcium, which can bind to fat in the intestine. Why is there nothing that does the opposite? Of course, I'm sure part of the answer is that so many people need to lose weight for health reasons, but what about people with digestive disorders, for example? These people are mainly just told to avoid certain foods, right? Why isn't there a pill you can take that helps you absorb more fats or carbohydrates? What would be some of the possibilities here (besides, say, expensive digestive enzymes)? Of course, I'm sure there's more interest in reducing energy harvest to reduce obesity, but what could you do (in theory) to help the gut absorb more calories? I've read that even in healthy people, fecal energy content varies significantly (typically between 2-10%), so I think there would be some room for improvement even in healthy individuals (e.g., those wanting to gain weight). Clearly, putting any meaningful number of calories in a tiny pill is impossible, but why can't we make weight-gain pills that help the body absorb more calories from food?173.185.94.69 (talk) 15:46, 6 September 2021 (UTC)[reply]

There's taking antibiotics to kill off gut bacteria and reduce competition, but that's not encouraged. Apparently there's some evidence that antibiotics can cause weight gain, but I'm sure it's debatable how big the impact is. Blythwood (talk) 16:16, 6 September 2021 (UTC)[reply]

In several million years, evolution has fine-tuned the hominid digestive system for maximal energy harvesting. It is a very complex system, and one should not expect that a simple intervention can substantially increase the yield. --Lambiam 19:52, 6 September 2021 (UTC)[reply]

There is such thing as digestive enzyme supplementation. Ruslik_Zero 20:30, 6 September 2021 (UTC)[reply]

Okay, thank you!173.185.94.69 (talk) 21:31, 6 September 2021 (UTC)[reply]

September 7

How can exercise burn stress?

From here, it says: When you exercise, you'll burn off some of your stress.

I know exercise burn calories but how it can burn stress too? Rizosome (talk) 01:41, 7 September 2021 (UTC)[reply]

Start with Exercise, note where it mentions "stress", and continue from there. ←Baseball Bugs ^{What's up, Doc?} carrots→ 02:36, 7 September 2021 (UTC)[reply]

STRESS RELIEF - The Role of Exercise in Stress Management describes the hormonal changes involved. The use of the term "burn" seems to be just journalese rather than an accurate description of the process. Alansplodge (talk) 21:06, 7 September 2021 (UTC)[reply]

Special relativity question

Suppose you have a train and its rest length is known. It runs on a track. On one side of the track and there are two light sources shining across the track, perpendicular to it. They are a known distance apart. On the other side of the track, the beams are reflected by mirrors into detectors that are at the position of a clock. The detectors record the time from the clock when they are receiving the light and when they are not. The apparatus is symmetrical with respect to the clock.

The train comes along the track at relativistic speed and the apparatus records the time each light beam is cut off and the time it resumes.

From the time that each beam is cut off and the known distance between the light beams, you can calculate the speed of the train. From that and the length of time that the light is cut off from either beam, you can calculate the length of the train.

Question: This calculated length of the train will show Lorentz contraction, right? Bubba73 ^{You talkin' to me?} 02:52, 7 September 2021 (UTC)[reply]

Is this the same as the ladder paradox? Robert McClenon (talk) 05:41, 7 September 2021 (UTC)[reply]

I don't think it is. The ladder paradox says "This apparent paradox results from the mistaken assumption of absolute simultaneity. " I don't see any use of absolute simultaneity. Bubba73 ^{You talkin' to me?} 06:22, 7 September 2021 (UTC)[reply]

Yes, the Lorentz contraction is a real physical, and measurable, phenomenon, not just a mathematical trick. If you were to measure the length of an object moving at close to the speed of light, it will be smaller in the direction of travel than if you measured it while stationary. This video does a good job of explaining it. --Jayron 32 16:18, 7 September 2021 (UTC)[reply]

Also relevant, this most recent video from Minute Physics has a different experiment to measure length contraction. --Jayron 32 16:20, 7 September 2021 (UTC)[reply]

Yes, that method will show Lorentz contraction of the train's length. --Amble (talk) 20:05, 7 September 2021 (UTC)[reply]

Resolved

That is what I thought, thank you. Bubba73 ^{You talkin' to me?} 21:30, 7 September 2021 (UTC)[reply]

Smartphone's screen smudges

Even though internet states that smartphone screens have an oleophobic coating, the finger smudges on the screen are still there (in my case it's Motorola E7i, but I guess any other smartphone has the same). Is it because the oleophobic coating is too thin to prevent smudges or some other reason? More generally, is it possible to produce a smudge-resistant touch screen? 212.180.235.46 (talk) 19:46, 7 September 2021 (UTC)[reply]

A thicker coating layer will not reduce the amount of sebum transferred to the screen. Such transfer takes place at the outer surface of that layer. No coating can guarantee a full 100% protection against smudge attacks, but matte screen protectors make such attacks less easy. I did not readily see information about the affinity to oil or lack thereof of the Motorola E7i screen, but ads offering oleophobic screen protectors for this model abound. --Lambiam 07:10, 8 September 2021 (UTC)[reply]

Removing ticks?

Just for future reference because i forgot. Are you supposed to twist the tick clockwise or anti clockwise to get it out? 146.200.107.70 (talk) 23:10, 7 September 2021 (UTC)[reply]

Neither. Here's how.[8] ←Baseball Bugs ^{What's up, Doc?} carrots→ 01:54, 8 September 2021 (UTC)[reply]

September 8

Is there a world map that colors pixels by which staple crop has the most human-edible tons/acre potential there?

Weight the way it's usually measured, I think it's dry weight. Or calories per acre, which might penalize maize for its low fat and indigestible but edible shell. Sagittarian Milky Way (talk) 06:35, 8 September 2021 (UTC)[reply]

This looks like it might meet your needs. --Jayron 32 11:55, 8 September 2021 (UTC)[reply]

September 9

Covid question

We know that if a vaccinated person catches Covid, the risk of long Covid or complications is much lower compared to if an unvaccinated person catches Covid.

But is catching Covid from a vaccinated person less dangerous than catching Covid from an unvaccinated person?

Logic is the virus would be weakened by the vaccinated person's immune system.

--219.75.107.21 (talk) 09:36, 9 September 2021 (UTC)[reply]

The immune system doesn't weaken the virus per se: the virus particle should be exactly the same whether it comes from an unvaccinated person or a vaccinated breakthrough case. Virus particles are made new each time, it's not like they're "worn out" from fighting the vaccinated person's immune system. However, there's evidence that people who've been vaccinated tend to produce less virus and for a shorter period of time, figure 1 of this pdf. ~~I can't find the specific graph I'm thinking of though annoyingly.~~ It shows virus levels produced dropping much faster in vaccinated people on average than unvaccinated. How much this matters depends on the question of exactly how many virus particles are needed to infect someone.

One scenario people worry about with vaccines is Marek's disease, in which it's been suggested that a weak vaccine used on battery chickens has encouraged the evolution of more aggressive virus variants to beat the effect of vaccination. However, it's important to note that i) the vaccine still works very well in stopping the disease, and ii) this is a one-off, there are dozens and dozens of other vaccines which have been used for decades without seeing anything like this kind of effect. Although I haven't found a source specifically pointing to this, my guess is that a major factor there is the tremendously confined nature of battery farming, that squashing huge numbers of chickens together makes it easier for the virus to spread from infected chickens to uninfected ones quickly. Blythwood (talk) 11:03, 9 September 2021 (UTC)[reply]

What's a battery chicken? ←Baseball Bugs ^{What's up, Doc?} carrots→ 11:05, 9 September 2021 (UTC)[reply]

See Battery cage. --Wrongfilter (talk) 11:23, 9 September 2021 (UTC)[reply]

On that point, challenge studies have started in Britain to study questions like this. They seem to be way more altruistic than I to allow a pandemic infection on purpose. Imagine Reason (talk) 20:53, 11 September 2021 (UTC)[reply]

September 10

Why did NASA planned JWST deployment for 3 weeks process?

Here it says: Once in position, JWST will go through the process of deploying its sunshade, mirror, and arm, which will take around three weeks.

Why three weeks instead of deployment right after entering into Halo orbit? Rizosome (talk) 00:22, 10 September 2021 (UTC)[reply]

It's not saying that they're waiting 3 weeks and then they begin the deployment; it's saying the deployment takes 3 weeks to complete. The deployment process begins a few hours after launch, long before the telescope reaches its final halo orbit, as the diagram shows in the article that you linked to. Part of the time required for the process is apparently waiting for the telescope to cool down after the sun shade is deployed. There's a more detailed timeline here. CodeTalker (talk) 01:04, 10 September 2021 (UTC)[reply]

Apollo failure plan

If Armstrong & Aldrin (or any pair of their successors) could not leave the Moon, I guess they'd carry on doing whatever science they could until they ran out of air or water, and then open their helmets to vacuum; but has anyone in a position to know said anything publicly? —Tamfang (talk) 00:37, 10 September 2021 (UTC)[reply]

I think the contingency plan for Apollo 11 was to close down communications. The scientific part of the mission was extremely limited, after quickly deploying a seismometer and a laser ranger and collecting a few rocks to be analyzed back on Earth, there was nothing left to do for Armstrong and Aldrin in the way of science. --Lambiam 08:23, 10 September 2021 (UTC)[reply]

Plenty of hits if you google "apollo failure plan". I don't know how much is accurate. This https://www.space.com/if-apollo-11-astronauts-died-nixon-contingency-speech.html mentions a contingency speech by Nixon; this was also mentioned in an Apollo documentary I saw recently on the Smithsonian TV channel. Thankfully, the Apollo missions were successful. I remember in the Australian news, speculation that Luna 15 might have been an emergency escape plan. --TrogWoolley (talk) 09:48, 10 September 2021 (UTC)[reply]

I'm not sure they'd need to expose themselves to vacuum as both their spacesuits and the lander itself both used recycler technology to maintain a breatable atmosphere. So if the Oxygen supply ran out before the scrubber the astronauts would have lost conciousness and died due to hypoxia without the unpleasant sensation associated with asphyxiation caused by hypercapnia. 2A01:E34:EF5E:4640:9CF5:EEC0:F336:157F (talk) 13:49, 10 September 2021 (UTC)[reply]

They came very close to being stuck on the Moon. Count Iblis (talk) 17:07, 10 September 2021 (UTC)[reply]

I think they had backup methods. I think they could simply turn some valves by hand to start the engine. Bubba73 ^{You talkin' to me?} 04:05, 12 September 2021 (UTC)[reply]

If a freak meteorite destroyed the CM at touchdown how far from the landing site could they get, if they decided on a whim to make the distance record as hard to break as possible? Is the rover faster with one man or two? (for traction or balance or something) Could the throttle control be tied, taped or jammed in the "on" position? Sagittarian Milky Way (talk) 21:36, 10 September 2021 (UTC)[reply]

Perpetual motion of water

Greetings!

I found this video of perpetual motion (here) in which 4 watering cans are situated so that siphoning water through the spout of one can into the filling hole of another permits one to link a a number of cans so that they fill one another without any intervention and will continue to do so ad infinitum unless disturbed.

Why can't we harness the falling water with a water wheel and draw power from such a system? If we did, it seems we'd be drawing power from a perpetual motion machine, which seems to be a violation of the first law of thermodynamics.

Thanks!

DRosenbach ^{(Talk | Contribs)} 13:00, 10 September 2021 (UTC)[reply]

The first law of thermodynamics tells us this cannot be a source of perpetual motion. There is some "trick" involved as can be seen in the video - notice that when the operator sets the water in the first 3 watering cans into motion, he then steps backwards and stops adding water to the 1st can but the 1st can continues to pour water into the 2nd can, even though water hasn't started flowing from the 4th can into the 1st can! Notice that after the operator first stops adding water to the 1st can the water level in that can remains completely full even though water is pouring out of the 1st can into the 2nd. Some sort of trick must be involved because how could water be flowing from the 1st can into the 2nd when no water is yet flowing into the 1st from the 4th? The trick may be that there is a cut in the filming which is not detectable to anyone watching the video, but during the cut some other source of water (not visible to the viewer) is connected to the 1st can, and then filming resumes. Dolphin (t) 13:24, 10 September 2021 (UTC)[reply]

Funny, when I overfill a watering can, the extra water just spills out of the filling hole. Water only starts to come out of the spout if I tilt the can. The person in the video seems to be playing with a different physics ruleset. --Amble (talk) 22:37, 10 September 2021 (UTC)[reply]

Any holes below your filling hole? Sagittarian Milky Way (talk) 01:16, 11 September 2021 (UTC)[reply]

No, which is why pouring water in the filling hole of a real watering can sitting flat on the ground doesn’t cause water to come gushing out of the higher spout, as it appears to do in the video. —Amble (talk) 02:21, 11 September 2021 (UTC)[reply]

I wonder if there's a hosepipe hidden inside one of the watering cans feeding out the spout. Sort of like Brian Wansink's (supposed) bottomless soup bowl experiment. Blythwood (talk) 03:48, 11 September 2021 (UTC)[reply]

I think it was probably done with video editing. But if not, maybe a small submersible pump hidden inside the can? --Amble (talk) 22:13, 11 September 2021 (UTC)[reply]

Are short codons possible?

I just can't seem to find any references for this. My question is relatively simple. Is it possible for a codon to consist of less than three bases? Earl of Arundel (talk) 13:29, 10 September 2021 (UTC)[reply]

I'm not sure I understand your meaning. Do you mean "Could someone imagine a fictional biological system that used two- or one-base codons" or do you mean "are there examples of exotic forms of life that use two- or one-base codons that we know about"? --Jayron 32 13:33, 10 September 2021 (UTC)[reply]

Precisely, the latter. And moreover what might happen if the DNA/RNA "machinery" actually did encounter a shorter snippet at the end of a chain? Eg. Would it destroy the strand, ignore the snippet, make an amino acid anyway, just get confused? Earl of Arundel (talk) 13:50, 10 September 2021 (UTC)[reply]

Our Genetic code article has a section on variants of the code, but the variants mostly involve changing the meaning of a small number of 3-base codons. The article says Despite these differences, all known naturally occurring codes are very similar. The coding mechanism is the same for all organisms: three-base codons, tRNA, ribosomes, single direction reading and translating single codons into single amino acids. (emphasis added) CodeTalker (talk) 20:12, 10 September 2021 (UTC)[reply]

Of course it isn't much of a stretch to imagine some rare cases where physical damage to a strand of DNA (due to radiation or what have you) could however cause that sort of thing to happen. Surely the cells have some way of dealing with those kinds of errors. Earl of Arundel (talk) 15:17, 11 September 2021 (UTC)[reply]

Our Codon degeneracy article notes the important point that the number of codons sets a limit on the number of different amino acids that can be encoded. Going the other way (and drifting off the original specific question), doi:10.1093/nar/gnj003 demonstrates development of four-base codons. DMacks (talk) 15:26, 11 September 2021 (UTC)[reply]

Okay, so cells are often able to mitigate for these irregular chains, but mutations sometimes do occur instead. Well that makes sense. And thank you for the links! Earl of Arundel (talk) 19:45, 11 September 2021 (UTC)[reply]

What if they'd used respirators?

[9] Imagine Reason (talk) 14:40, 10 September 2021 (UTC)[reply]

Is there a question? --OuroborosCobra (talk) 17:54, 10 September 2021 (UTC)[reply]

Inaccessible link. --CiaPan (talk) 20:54, 10 September 2021 (UTC)[reply]

9/11 Survivors Are Still Getting Sick Decades Later: ‘Am I Next?’ It's an interesting question, but is either trivial or calls for speculation, which we won't do here. Certainly hazmat suits would have resulted in fewer people being exposed to toxins and thus fewer long-term problems. --jpgordon^{𝄢𝄆𝄐𝄇} 22:26, 10 September 2021 (UTC)[reply]

I'd have thought that there'd be a lot of science done now on the effects of building destructions on air quality and the usefulness of filtering masks in such air. Imagine Reason (talk) 20:49, 11 September 2021 (UTC)[reply]

Do vaccine booster shots need to be same as original vaccine?

Not a request for medical advice, but rather a general question. When a vaccine booster shot is given, does it need to be the same as the original vaccine? COVID vaccine booster shot is what brings this to mind (if someone had the Pfiser vaccine originally, can they get Moderna as the booster?) but also curious about other vaccines that require booster shots. RudolfRed (talk) 20:12, 10 September 2021 (UTC)[reply]

By "booster" I mean, for example, a third shot of a two-shot series given some time (6+ months) after the original. RudolfRed (talk) 20:22, 10 September 2021 (UTC)[reply]

See Mix-and-match COVID vaccines trigger potent immune response (19 May 2021). Alansplodge (talk) 21:58, 10 September 2021 (UTC)[reply]

As to COVID vaccines, the three vaccines principally used here in Canada fall into two major types: the Pfizer and Moderna vaccines are mRNA vaccines while AstraZeneca's is a viral vector vaccine. The Advisory Committee on Immunization recommended in June that "When the first dose in a COVID-19 vaccine series is an mRNA vaccine, the same mRNA vaccine product should be offered for the subsequent dose if readily available. When the same mRNA vaccine product is not readily available, or is unknown, another mRNA COVID-19 vaccine product recommended in that age group can be considered interchangeable and should be offered to complete the series"; and that "When the first dose in a COVID-19 vaccine series is the AstraZeneca/COVISHIELD vaccine, either the AstraZeneca/COVISHIELD vaccine or an mRNA vaccine product may be offered for the subsequent dose to complete the series, however an mRNA vaccine product is preferred as a subsequent dose due to emerging evidence including the possibility of better immune response...". As far as I know this advice hasn't changed. --184.144.99.72 (talk) 04:29, 11 September 2021 (UTC)[reply]

As a majority of COVID vaccines is based on the full length spike protein (or even on the whole virus) they are probably interchangeable. Ruslik_Zero 20:16, 11 September 2021 (UTC)[reply]

Thanks, everyone, for the information and replies. RudolfRed (talk) 21:36, 11 September 2021 (UTC)[reply]

September 11

Which ship would be drowned faster in case of raging / stormy sea?

Which ship would be drowned faster in case of raging / stormy sea, a ship that has a heavy load or the similar ship that has lighter load? I'm not sure if a load plays a positive role in such a situation or not.--ThePupil (talk) 00:07, 11 September 2021 (UTC)[reply]

The Book of Jonah says heavier but take that with a grain of salt. Completely different technologies from that fable. Sagittarian Milky Way (talk) 01:14, 11 September 2021 (UTC)[reply]

Larger vessels, be they in the sea or the air, can usually handle storms better than smaller ones. ←Baseball Bugs ^{What's up, Doc?} carrots→ 02:23, 11 September 2021 (UTC)[reply]

The question was about similar ships, not smaller and larger ones. Cargo ships are designed to be able to operate in a "raging/stormy sea" if necessary: if they sink it's because something went wrong, for example a hatch cover breaking or coming unlatched, leading to flooding of a hold. Further, a lightly loaded ship may contain ballast that would affect the scenario. I don't think it's reasonable to speculate about specific possibilities: there is too much room for variation. --184.144.99.72 (talk) 04:37, 11 September 2021 (UTC)[reply]

The most likely doom scenario in a storm is the ship capsizing, which can happen if it is hit broadside by a large wave. The stability of the ship is related to the height of the centre of mass of the vessel together with its load. Relative to the height of the centre of mass of the unloaded vessel, the centre of mass of the loaded vessel will be higher if the load is all on deck, and lower if stowed in a below-deck cargo hold. So depending on how the ship is loaded, it may be less stable or more stable than when carrying no load. If the vessel is designed to be self-righting, a lower centre of mass (on the upright vessel) also supports its righting after capsizing, while a top-loaded ship, even if designed to be self-righting, may not overcome the capsizing – which can also be triggered by the load shifting on deck if it is not securely stowed. Capsizing does not necessarily imply that the ship will sink; the air that remains trapped, as well as any cargo whose density is less than that of the surrounding water, may provide enough buoyancy to keep it afloat. --Lambiam 08:56, 11 September 2021 (UTC)[reply]

What's the point of poison fruits ?

What's the point of poison fruits if its main aim is to spread seeds by birds/animals? Rizosome (talk) 00:30, 11 September 2021 (UTC)[reply]

Most fruits have been evolved to be consumed by one or a few particular species, to whom they are not poisonous: a given substance can be non-poisonous (or distasteful) to some species of birds or animals, but poisonous (or distasteful) to others such as humans. Fruits that are poisonous to humans are not poisonous to the species that normally eat and thus propagate them in the wild.

Until very recently, in evolutionary terms, humans were so few in number compared to other species of animals and birds that it is unlikely any fruit evolved by natural selection to be non-poisonous specifically to humans. However, since agriculture was invented, humans have selectively bred some fruits, a process called artificial selection, to make them less or non-poisonous. Also, some fruits poisonous to humans in an unprepared state may be rendered edible by various methods of preparation. {The poster formerly known as 87.81.230.195} 90.200.67.3 (talk) 01:07, 11 September 2021 (UTC)[reply]

Bear in mind that there is no "point" to evolution. It's a natural process. ←Baseball Bugs ^{What's up, Doc?} carrots→ 11:27, 11 September 2021 (UTC)[reply]

Lewis acids/base questions.

What are some examples of Lewis acids with basic pHs? Googling Lewis acids with basic pH didn't return anything that specific. So it recently occurred to me that Lewis bases can have acidic pHs, an example is hydrogen peroxide. Although hydrogen peroxide could be an Arrhenius acid, in actuality it is unstable in alkaline solutions rendering it not happening. So hydrogen peroxide is more of a Lewis base than a Arrhenius acid (thus Lewis acid). But its pH is in the weak acid range. Are there any other examples like this, as well as Lewis acids with weak-base pH? Thanks. 67.165.185.178 (talk) 05:38, 11 September 2021 (UTC).[reply]

Are you asking about amphoterism? DMacks (talk) 15:28, 11 September 2021 (UTC)[reply]

Sure. Should amphoterism be mostly about something that can be a Lewis acid and a Lewis base, or say, a Lewis acid and a Arrhenius base, and Lewis base and a Arrhenius acid? 67.165.185.178 (talk) 15:53, 11 September 2021 (UTC).[reply]

Aluminium hydroxide is a Brønsted–Lowry base, so an aqueous solution of it would have a high pH, but it also acts as a Lewis acid. --OuroborosCobra (talk) 21:40, 11 September 2021 (UTC)[reply]

September 12

heart condition from joke

There is a corny joke/prank that kids play on each other. You shake the other person's hand, but while doing so, you give it a series of pulsating squeezes, like a heartbeat, and say "Hi, I'm from the heart association". (I told you that the joke was corny).

I learned this joke in school and tried it on my dad, who got a chuckle out of it. It turns out he had a professional acquaintance who was a heart surgeon, so when the opportunity next came up, he tried the joke on the surgeon. The surgeon, without missing a (no pun intended) beat, said something like "you've got aortic deficiency" or some other such medical condition. One got the impression that the surgeon had been through this many times before, and had the answer worked out ahead of time.

I had remembered "aortic deficiency" but WP doesn't have an article about that, so maybe I have it wrong. Is there another condition that sounds like that, which would fit the situation? 2602:24A:DE47:B8E0:1B43:29FD:A863:33CA (talk) 01:32, 12 September 2021 (UTC)[reply]

Aortic insufficiency. Abductive (reasoning) 04:12, 12 September 2021 (UTC)[reply]

If acid/bases are opposites then why they react on human skin equally?

Endothermic and exothermic are treated opposite based on their hot and cold reactions but in case of acids/bases, they are treated as opposites in ph scale, but they react on human skin equally, why so? Rizosome (talk) 01:43, 12 September 2021 (UTC)[reply]

Each acid and base reacts differently to human skin. Some chemicals can cause what we call "chemical burns," and these injuries are in no way equal. An important feature of reality is that human language is inadequate in describing reality. 2600:1702:2670:B530:45D:3246:2D5F:FEC0 (talk) 02:46, 12 September 2021 (UTC)[reply]

True. The OP needs to keep in mind that the terms "acid" and "base" are general chemical classifications. The corrosive aspects of individual examples vary. One item is Citric acid, which is mild enough to be used in food, even though in its pure form it can be troublesome. ←Baseball Bugs ^{What's up, Doc?} carrots→ 03:42, 12 September 2021 (UTC)[reply]

The broad effects of acids and bases on skin are also different. [10]--Wikimedes (talk) 05:39, 12 September 2021 (UTC)[reply]

@@ Line 259: / Line 259: @@
 :Each acid and base reacts differently to human skin. Some chemicals can cause what we ''call'' "[[chemical burn]]s," and these injuries are in no way equal. An important feature of reality is that human language is inadequate in describing reality. [[Special:Contributions/2600:1702:2670:B530:45D:3246:2D5F:FEC0|2600:1702:2670:B530:45D:3246:2D5F:FEC0]] ([[User talk:2600:1702:2670:B530:45D:3246:2D5F:FEC0|talk]]) 02:46, 12 September 2021 (UTC)
 ::True. The OP needs to keep in mind that the terms "acid" and "base" are general chemical classifications. The corrosive aspects of individual examples vary. One item is [[Citric acid]], which is mild enough to be used in food, even though in its pure form it can be troublesome. ←[[User:Baseball Bugs|Baseball Bugs]] <sup>''[[User talk:Baseball Bugs|What's up, Doc?]]''</sup> [[Special:Contributions/Baseball_Bugs|carrots]]→ 03:42, 12 September 2021 (UTC)
+:::The broad effects of acids and bases on skin are also different. [https://study.com/academy/lesson/alkali-burns-vs-acid-burns.html]--[[User:Wikimedes|Wikimedes]] ([[User talk:Wikimedes|talk]]) 05:39, 12 September 2021 (UTC)