Wikipedia:Reference desk/Archives/Science/2020 November 13

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November 13

Fuse labelling

I'm replacing an axial ceramic fuse. The end cap is labelled F5AH250V. So it's 5 Amp at 250V. Is the F fast blow? And what is the H? Does this refer to the "class H fuses" mentioned in our article Fuse (electrical)? All the best: Rich Farmbrough 11:14, 13 November 2020 (UTC).

Yes F is Fast Acting, alternatives FF, M T or TT; H stands for High Breaking Capacity - alternative E or L. IEC 127 describes the layout. Graeme Bartlett (talk) 11:39, 13 November 2020 (UTC)

To save people some googling: [1]. DMacks (talk) 17:17, 13 November 2020 (UTC)

Is there a common disease happens by exposure to dogs feces?

It's well known that toxoplasmosis is a disease usually caused by the exposure (touching) of cats faeces, which transfers this parasite. Is there a parallel common disease/s that happens due to exposure to dogs faeces? Or usually, unlike cats faeces, dogs faeces are clean of diseases transfer to a human being? --ThePupil (talk) 11:31, 13 November 2020 (UTC)

Yes. Toxocariasis. -- The Anome (talk) 11:31, 13 November 2020 (UTC)

_{Anyone ever notice that faeces, diarrhoea, labour look less attractive in British spelling? (cause if these words existed in the Yank country they'd be pronounced something like 'fāy•sēs, dī•a•'rhō•a and 'lā•'boor) Sagittarian Milky Way (talk) 18:17, 13 November 2020 (UTC)}

It's because we find faeces and diarrhoea unattractive that we don't like the idea of American food standards. DuncanHill (talk) 00:51, 14 November 2020 (UTC)

Foetus and mouldy oesophagus just look awful, all these words look even worse than if the false pronunciations were spelt an American way like fowtus, fowtal position, mooldy fayces and so on. Sagittarian Milky Way (talk) 17:30, 14 November 2020 (UTC)

Mars and water

Is it possible for sand to act in the same manner as water. Given the correct conditions. If the sand is super-fine grained such as has never been seen on earth, could the sand act in the same way as water in weathering of rocks, formation of canyons etc? I would assume that if the particles were small enough they would act in the same way? Thank you

Yes, to some extent. That's granular flow (that link is a redirect to an article that doesn't adequately cover granular flow).

• Grush, Loren (22 November 2017). "Flowing water on Mars' surface may just be rolling sand instead". The Verge.
• Khan, Amina (21 November 2017). "Mars may not have the water we thought it did, study shows". Los Angeles Times.

--107.15.157.44 (talk) 15:11, 13 November 2020 (UTC)

There is also the process of Soil liquefaction, but that requires some water. --Jayron32 17:04, 13 November 2020 (UTC)

Liquefaction also requires vibration (i.e. marsquake). 107.15.157.44 (talk) 20:40, 13 November 2020 (UTC)

The sand grains don't need to be particularly fine to cause erosion. See Aeolian processes.--Shantavira|^{feed me} 09:09, 14 November 2020 (UTC)

What is the least practical pure normal alkane to burn?

If you could magically make each pure n-alkane as cheap as the cheapest petroleum product that is similar to it (like if n-octane cost the same as petrol the common Joe can buy, methane as natural gas, hexadecane as some grade of heating oil, docosane as candle-type paraffin, crap ship fuel as the most similar n-alkanes and so on) then which n-alkanes would not burn good in anything common or have the least common practical fuel uses? If it is simply tar molecules the longer the better (as I suspect) then what is the least practical that can at least run a ship or be made into candles? Sagittarian Milky Way (talk) 22:31, 13 November 2020 (UTC)

Some large transport ships run on Heavy fuel oil aka bunker oil. This is treacle-like at room temperature, and is 30-40 carbons long [2]. It has to be warmed before running on diesel-type engines, and they run at less than 100 rpm [3]. LongHairedFop (talk) —Preceding undated comment added 22:19, 14 November 2020 (UTC)

Can you take multiple vaccines for the same thing?

There are a couple dozen vaccines in development for covid-19. Initial data indicates that Pfizer's is 92% effective. What about the other 8%? Is it possible to take more than one vaccine for the same thing? A Quest For Knowledge (talk) 23:41, 13 November 2020 (UTC)

What information have you found from your Google search of the subject? ←Baseball Bugs ^{What's up, Doc?} carrots→ 00:33, 14 November 2020 (UTC)

Sure, why not? A more pertinent question might be, is there a point to doing so? The influenza vaccine is one case where there is. There are multiple strains of flu virus, and their antigens gradually shift over time, so there are two yearly formulations, for the Northern and Southern Hemispheres. --47.152.93.24 (talk) 03:51, 14 November 2020 (UTC)

It's not clear (to me anyway) if the 92% level is due to there being multiple strains or something else. The annual flu vaccine is kind of like providing you with a set of three keys instead of just one; if one doesn't work against a particular strain, hopefully one of the others will. COVID-19 has already mutated in multiple ways, at least one of which - Cluster 5 - is "unlikely to respond to COVID-19 vaccines under development." But that's a (so far) isolated strain not figuring into the 8% fail rate. This seems to be the most detailed breakdown of the testing, but I don't see anything in there about what might have caused the failures or even if multiple strains were tested against. Note also: "The results have not been peer-reviewed by outside scientists or published in a medical journal, and even Pfizer and BioNTech have been given no other details about how the vaccine performed by the independent monitors overseeing the study." Matt Deres (talk) 16:11, 14 November 2020 (UTC)

For clarity, as understand it, no human challenge studies have been used for COVID-19, at least that we know of. They've been considered COVID-19 vaccine#Proposed challenge studies but I think concern over the ethics combined with the fact SARS-CoV-2 is spreading quite well in certain areas has meant they haven't been used. So there isn't really testing against any specific strain, at least not in the human trials. Instead, it's just giving a large enough group of people in areas where it's spreading either a placebo or the vaccine (in a double blind fashion), then waiting for enough of them to be confirmed to have COVID-19 from the naturally circulating strains, then looking at how many of those were on the placebo and how many were vaccinated. (To be clear, you're monitoring and looking at other things, but as I understand it that's how you work out the efficacy.) Note also as I understand it and mentioned in my response below, 90% efficacy is very promising if correct. The concern is not so much the other 10%, but whether that 90% will hold especially when the vaccine is given to people with weaker immune systems like the elderly, who are also those who are most at risk, as well as other groups of people. (Different strains will likely also be a concern.) How long the immunity last is another obvious concern. Nil Einne (talk) 18:26, 14 November 2020 (UTC)

Nota bene: quadrivalent flu vaccines are increasingly used over trivalent (four "keys" compared to three). In the U.S., all flu vaccines have been quad for the past couple years. Influenza vaccine § Quadrivalent vaccines for seasonal flu --47.152.93.24 (talk) 23:01, 14 November 2020 (UTC)

Different vaccines for a virus attack the virus at different weak spots. A mutation might create a strain that vaccination with vaccine A no longer protects against, while the protection of vaccine B remains effective. This could be a reason for receiving vaccinations with multiple vaccines. Setting mutations apart, the combined protection of multiple vaccines is probably higher than that of any single one. For the foreseeable future, such multiple vaccination for COVID-19 will be something that very few people will be able to receive. But perhaps an anti-COVID-19 cocktail vaccination will become routine by Fall 2022.  --Lambiam 11:08, 14 November 2020 (UTC)

This answer needs some major clarification. Vaccines don't really target or attack "weak spots". They are not drugs. Instead they try to induce immunity by introducing an antigen derived from the virus, which you body will hopefully learn to recognise as a "threat"/"foreign" and so if the real virus comes along, it will also be quickly recognised as "foreign" an attacked by antibodies. You do want the right target to ensure you produce neutralising antibodies, so to that extent you could say the targets are "weak points". Although what that means is when an antibody binds to that target, it prevents infection or pathogenicity, rather than the site being a particularly susceptible part of the virus.

For obvious reasons, the antigen targeted is ideally something that changes little. As I understand it, nearly all vaccines for COVID-19 have focused on the spike protein for that reason. I believe that's why current vaccines are generally considered to likely fail with the Cluster 5 (as Matt Deres mentions), that came from minks, as it has several mutations on the spike protein.

Clearly the vaccines aren't all the same, indeed one of the somewhat unusual things is there are a significant variety of COVID-19 vaccine#Technology platforms under very active development. E.g. BNT162b2 uses mRNA, something no other commercial vaccine uses. (BTW, it's efficacy was reported as 90%. 92% is what was claimed for Sputnik V which is also a fairly different type of vaccine.)

While it's possibly that combining multiple vaccines would increase efficacy, this is likely something that will need to be proven via trials, as Matt Deres also mentioned, there's actually a reasonable chance it won't have much effect on efficacy. In addition, the safety effects of combining vaccines will likely need to be studied.

It's also possible that one vaccine will still be effective against some mutation but another won't be, but this is IMO something only likely to be dealt with if the need arises, and frankly unless you need vaccine 1 for strain 1, and vaccine 2 for strain 2, the most likely scenario is just abandoning the one that no longer works so well.

Remembering also that vaccines work on a community level so as long as supplies are constrained, giving vaccine 1 to person 1 and vaccine 2 to person 2 is likely to make more sense. While vaccine distribution is likely to be very inequitable, I think most of those involved in the decisions in wealthy developed countries are likely to recognise once they have enough of some effective vaccine for their citizens, it'll probably be better even for their citizens to let people in other countries have the the extra vaccine rather than giving the citizens two. Especially given the high levels of efficacy that seem to have been achieved. (If efficacy was low, I could imagine trying to see if combining 2 helps may have happened with far greater urgency.)

Nil Einne (talk) 17:20, 14 November 2020 (UTC)

+1 to Nil Einne's response, and also I want to emphasize that the initial result indicating 90% interim VE is outstanding, considering the threshold set by FDA for licensure is 50%. And it doesn't mean 10% of those who received the vaccine ended up getting COVID-19--it means there was a 90% reduction in risk among the vaccinated group as measured by disease incidence per 1000 person-years (the assumed attack rate among susceptible people is 1.3% per year). That said, VE in this case refers to efficacy, which is not a real-world parameter since it excludes certain populations from participating (e.g. those with particular comorbidities, kids under 12) and follows strict dosing, spacing, compliance, etc. The final VE will likely drop when generalized to more vulnerable people, but is still anticipated to be above 60%. JoelleJay (talk) 10:03, 16 November 2020 (UTC)

Isn't the increased vulnerability more about the prognosis once infected than about the risk of getting infected, which is what the efficacy measures?  --Lambiam 13:08, 16 November 2020 (UTC)

In this case, the endpoints for efficacy are risk of getting COVID-19, not risk of getting infected with SARS-CoV-2. So the vulnerable populations would include those with compromised immunity who are less able to defend against developing the disease if infected. JoelleJay (talk) 19:43, 16 November 2020 (UTC)