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November 10

Halley's Comet

Halley's Comet is due to return and be visible from Earth in 2061. What I would like to know is will this be visible from the northern as well as the southern hemisphere also what month and (preferably) day of the month will it be visible and thirdly will there be any other celestial events at the same time such as meteor shower, or is it too early to know? Thank you — Preceding unsigned comment added by 2a00:23c6:6884:6200:c4eb:9390:154f:c242 (talk • contribs)

You can look at our article: halley's comet for more information. Ruslik_Zero 20:51, 10 November 2020 (UTC)

As a general comment, a comet doesn't just zip into and out of view on a particular date. A bright comet may be visible every night for weeks or more, during which its position against the background of stars will vary gradually but noticeably. Typically, during that time at first it is just barely visible, then it gets brighter from one night to the next, then eventually it gets fainter again. It's not too early to predict where the comet will be on any particular date, but knowing for how long it will be bright enough to see is another matter. --174.95.161.129 (talk) 20:58, 10 November 2020 (UTC)·

I need latitude for max detail. Both hemispheres can see but some latitudes much different than others. Sagittarian Milky Way (talk) 22:06, 10 November 2020 (UTC)

Note also that the brightnesses of comets are notoriously hard to predict, even much closer to their inner-Solar system passages, let alone decades in advance. See here, for example, for details of why. {The poster formerly known as 87.81.230.195} 90.200.136.194 (talk) 00:54, 11 November 2020 (UTC)

November 11

High technology, neurons

Sorry for the inconvenience, I would like to know if my essay posted here https://www.youtube.com/watch?v=Ieuc3ABCMMA can work , please ? 2A01:CB0C:38C:9F00:353A:F859:81D1:E460 (talk) 19:08, 3 November 2020 (UTC)

To be honest, it is unclear what you are proposing and what you aim to achieve. Reconstructing the connections of a (human?) brain in a computer simulation so as to achieve (or inflict) consciousness, similar to the notion of a brain in a vat? What do children have to do with it? Should they understand the essay? Or should the brains to be dismantled be children's brains? Are you aware that "nerve cell" and "neuron" mean the same thing? Removing the outer membrane is an effective method of destroying it. The connections are made through the synapses; they are not like electrical connections; knowing which neurons connect to which neurons does not give enough information to simulate the activity of the network formed by the neurons.  --Lambiam 23:49, 4 November 2020 (UTC)

2A01:CB0C:38C:9F00:353A:F859:81D1:E460—Why are you even posting to YouTube? Can't you directly ask a question at the Reference desk/Science? Is it important that YouTube serve as an intermediary? Bus stop (talk) 03:08, 5 November 2020 (UTC)

In fact, I hoped that my essay will be able to be read by all, including children. I would like to use the simulation in order to re-inflict the consciousness function to the real original set of neurons,please ?2A01:CB0C:38C:9F00:E450:3436:FE14:781F (talk) 00:01, 11 November 2020 (UTC)

In fact, I would like to know if there is a way to extract the entire data ?

Not with current technology.  --Lambiam 11:07, 12 November 2020 (UTC)

And what we do, about my process ? Do we talk about it to the autorities ? — Preceding unsigned comment added by 37.166.33.181 (talk) 14:03, 14 November 2020 (UTC)

To this same question I told you some weeks ago on the French oracle that in order to emulate the function of a specific brain you need not only to know which of the 100 billion neurons is connected to which other, but also to know the specific excitability threshold of every one of some 10,000 synapses belonging to every one neuron. And it is completely possible that the excitability state of the synapses gets lost at death.

Your explanation in the video is completely missing the practical side of the procedure, but even if you ever succeed in measuring every single neuron from a frozen brain to see how they are wired, this will not help you to reconstruct or re-establish or even emulate the consciousness of the dead person regardless which technology you are able to use. And so long no autority would be interested in realizing your idea.

But if you can first develop a concrete process and show that 1) it is practicable and 2) it works, here you can find some suggestions about the financial side: Funding_of_science. 2003:F5:6F0B:1E00:C990:B89E:5A87:5709 (talk) 21:49, 14 November 2020 (UTC) Marco PB

November 12

Weather forecasting

Why is it that the weather forecast shows chance of precipitation over the weekend as relatively low (around 20-30%) yet the symbol shows rain? What does this actually mean? [1] 90.194.52.17 (talk) 14:21, 12 November 2020 (UTC)

That there is a possibility of rain, followed by the percentage possibility of it happening. --OuroborosCobra (talk) 15:24, 12 November 2020 (UTC)

Briefly summarized, the BBC website has editorial control and they may choose how they want to display a forecast: they get to pick the logos, the icons, and other user-facing content to reflect their editorial view of the weather. They are probably trying to make the weather forecast easy, fun, fast, and simple - which is totally reasonable for the audience that they expect. Various professionals who consume weather data often view the same data in one or more standardized formats.

It is important to contrast the nice "logo" format you see on consumer-grade weather websites to certain other formats that professionals often use to consume weather data: for example, a METAR or a TAF does not editorialize: it is consumed (frequently in monospaced font) in a manner that leaves the interpretation to the professional who consumes it. This is, in my estimation, a very important consideration when viewed through the lens of cognitive human-factors or "design": making things easy-to-consume by adding logos and pictures and color-schemes does not necessarily make things better or more correct.

The BBC has its own FAQ about their weather reporting:

• Questions about weather forecasting information.

The web- and television/radio- weather broadcasts by BBC are primarily sourced through the BBC Weather Centre, with many of the specific forecasts (and especially the weather warnings) originating from the government's Met Office:

• How weather forecasts are created, from the Met Office

The translation of technical weather data into a "logo" or "symbol", and an easy-to-consume "percent chance", is somewhat of an editorial decision that is largely governed by a standardized, science-driven methodology. There is frequently a human meteorologist overseeing the process, making sure that the predictions are sensible and accurate, and interpreting or adjusting them when there is a need.

• How a weather forecast is made - In 60 seconds, from the Met Office.

In the United States, our National Weather Service provides technical weather information and analysis, including a full-length Handbook on how to format weather reports: Federal Meteorological Handbook 1: Surface Weather Observations and Reports. They also train and publish information about probabilistic forecasting. Here's a great website on the topic:

• Probabilistic Forecasting - A Primer, put out by the National Severe Storms Laboratory. It's a little bit technical, but if you're mathematically inclined, this is a huge help to understanding exactly what it means when the weather forecaster says "20% chance," or something like that. It is subtle, but it's important: there is a closed-loop process to verify forecasts: we can look at all the times over the last ten years that any specific professional or computer-program speculated a 20% chance for an event, and compare against what actually happened; and what we seek is that 20% of the time, they should have speculated correctly. This ensemble nature is the exact conceptual development that allows us to bridge from a single event (a "probability"), to the behavior across an ensemble of many events (the "statistics").

This is the academic guidance that American weather professionals follow; and it should be "similar" in the UK, but in the spirit of full disclosure, I don't know very much about the UK Met Office policies or training.

Incidentally, the use of repeated events to collect statistics, and perform post-fact methodological verification, is the exact reason why reported probabilities are pretty useless when we evaluate preditions for a one-time event - like an election! If our oracle predicts some specific outcome with a 75% probability, we do not have the ability to repeat that prediction many more times: there is no way to verify the oracle's methodological accuracy.

With the heightened awareness about "data science" creeping across every aspect of our lives, from politics to weather to climate to health to finance... there has never been a better day than today to crack open your old Statistics and Probability textbook and review the basics of numerical predictions for event likelihoods!

For the enthusiast, here is a long-form class from MIT's OpenCourseWare: Introduction to Probability and Statistics, with video lectures presented by Jeremey Orloff and Jonathan Bloom - all available online at no cost!

Long story short: there are people who care a lot about the numbers and symbols in those weather forecasts - they just aren't necessarily the same people who read the main BBC Weather webpage!

Nimur (talk) 19:37, 12 November 2020 (UTC)

The BBC decided to dispense with the services of the Meteorological Office (they thought they could get better service elsewhere) and signed a contract with a private company. However there were logistical problems and the changeover has yet to happen. 95.145.0.52 (talk) 10:26, 13 November 2020 (UTC)

They encountered difficulties while replacing a British public utility with a purportedly better-cheaper-faster private-sector alternative? How could they possibly have predicted?! Nimur (talk) 16:56, 13 November 2020 (UTC)

This discussion confuses me. All evidence I can see including from our articles MeteoGroup and BBC Weather which uses this source [2], along with the FAQ linked above [3], and other sources like [4] [5] [6] [7] [8] suggests the transition to Meteogroup happened in 2018 rather than there being logistical problems so the changeover has yet to happen or the BBC is still getting data direct from the Met Office. Per some of the sources, they still get the warnings from the Met Office, as I understand it that was always the plan although it seems they may not always feature them for whatever reason [9]. From that source, I'm not actually sure if they even get the warnings directly from the Met Office, or instead MeteoGroup provides them in their data feed, although the FAQ does mention they come from the Met Office. MeteoGroup is getting nearly all of their data from the Met Office and other generally government providers for world data [10], as with all? private forecasters. But AFAICT, the data you see on BBC nowadays is from MeteoGroup with their own analysis on top, not direct from the Met Office. Interesting this news article [11] found that the BBC forecasts were more accurate since the changeover, although as said it's just a news article analysis. Nil Einne (talk) 15:38, 15 November 2020 (UTC)

Aging

What is the evolutionary purpose of male pattern baldness and also of going grey. Thank you — Preceding unsigned comment added by 86.170.71.103 (talk) 14:59, 12 November 2020 (UTC)

Why does there have to be an "evolutionary purpose"? This is a common misconception when it comes to evolution. It doesn't have "purposes" or "goals". As long as people are still surviving to reproduction while carrying a trait, that trait will be passed on. On the "going grey" example, consider that most people start going grey long after the age at which they generally are having kids. Thus, it isn't really negatively impacting their ability to reproduce, and so there isn't a strong selective pressure against "going grey." As to why it happens at all, check this section on hair color, but basically, as we age a lot of cellular processes stop working so well. Among them, our cells that produce pigments at the base of hair follicles... stop producing pigments. It isn't so much that your hair is turning grey, rather it's that your hair stops turning some other color, like blond or brown. --OuroborosCobra (talk) 15:23, 12 November 2020 (UTC)

Is the silver in a silverback a greying process? --jpgordon^{𝄢𝄆 𝄐𝄇} 15:35, 12 November 2020 (UTC)

The right question could be, "What is the evolutionary advantage (if any)" for those traits. As to baldness, there's this old saying: "God is great / God is fair / To some men He gave brains / To other men, hair." ←Baseball Bugs ^{What's up, Doc?} carrots→ 15:47, 12 November 2020 (UTC)

The point is, as OuroborosCobra explained above, that not every trait needs to provide evolutionary advantages. They can be neutral, or they can even create a disadvantage, so long as it doesn't prevent the trait from being passed on reproductively, it will persist. --Jayron32 16:17, 12 November 2020 (UTC)

Also, the "bad trait" that appears later in life may be tied to a "good trait" that appears earlier in life. Anything that selects for the latter will also be selecting for the former. --Khajidha (talk) 17:17, 12 November 2020 (UTC)

Is there an evolutionary benefit to baldness quotes studies suggesting that it may be a signal of maturity or a means of increasing absorption of vitamin D. Alansplodge (talk) 09:33, 13 November 2020 (UTC)

This article writes: "It is fascinating to consider what possible evolutionary advantage might be conferred by stress-induced greying. Because grey hair is most often linked to age, it could be associated with experience, leadership and trust." They cite: Cunningham, M. R., Druen, P. B. & Barbee, A. P., "Angels, mentors, and friends: Tradeoffs among evolutionary, social, and individual variables in physical appearance", in Evolutionary Social Psychology (eds Simpson, J. A. & Kenrick, D.) Ch. 5 (Erlbaum, 1997), pp. 109–141.^[12]  --Lambiam 09:57, 13 November 2020 (UTC)

If there was a significant advantage wouldn't we be seeing many more bad men. Richard Avery (talk) 10:26, 13 November 2020 (UTC)

Khajidha's comment explains why bad genes which cause death do not disappear from the genome. 95.145.0.52 (talk) 10:32, 13 November 2020 (UTC)

Some info in our article at Human_hair_color. Matt Deres (talk) 17:21, 13 November 2020 (UTC)

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: [13]. 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 [14]. It has to be warmed before running on diesel-type engines, and they run at less than 100 rpm [15]. 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)

November 15

What's the quantity range of urine that a normal person has at one urination?

What's the quantity range of urine that a normal person has at one urination? I found the normal range for 24 hours only.--ThePupil (talk) 08:26, 15 November 2020 (UTC)

According to urinary bladder it's between 300 and 500ml.--Shantavira|^{feed me} 08:34, 15 November 2020 (UTC)

That sounds above average to me, both the bladder and the stomach explode slightly above 2 liters. (though this should only happen if a blockage prevents involuntary micturition or reflux) Sagittarian Milky Way (talk) 09:39, 15 November 2020 (UTC)

Also without explosion, withholding relief may be life-threatening; see Tycho Brahe#Illness, death, and investigations.  --Lambiam 10:12, 15 November 2020 (UTC)

That article shows he could only urinate tiny amounts with excruciating pain, that's constricted enough to plausibly burst bladder if he didn't die of urine toxins in the blood first as they suggest. Sagittarian Milky Way (talk) 19:33, 15 November 2020 (UTC)

With a 16.6% prevalence of overactive bladder symptoms in individuals aged 40 years,^[16] this condition is so common, though, that we should not consider people having it "abnormal". The prevalence increases with age, rising to 35% of those aged over 75 years old.^[17] With the same volume of urine output per day but a higher frequency, the quantity passed at one urination will be accordingly smaller; 150mL would not be abnormal.  --Lambiam 10:12, 15 November 2020 (UTC)

As concerns Tycho Brahe, enlarged prostate, says "BPH typically begins after the age of 40. Half of males age 50 and over are affected. After the age of 80 about 90% of males are affected...Symptoms may include frequent urination, trouble starting to urinate, weak stream, inability to urinate, or loss of bladder control." I'm sure others have considered this but I just thought I'd point it out. Bus stop (talk) 19:57, 15 November 2020 (UTC)

Is there a term for prey wrapped in silk?

I couldn't find it in Glossary of spider terms. I checked Nuptial gift and didn't see it there either. I learned from the article on Spider silk that the type of silk used for the practice is aciniform silk, but I can't a term for the practice itself, or for the end-product of the practice: an animal wrapped in silk. —Haikon 11:53, 15 November 2020 (UTC)

"Wrapping" is used in The evolution of prey-wrapping behaviour in spiders. --jpgordon^{𝄢𝄆 𝄐𝄇} 16:59, 15 November 2020 (UTC)

"Package" and "enswathe" are also used.[18] Nice image of spider spinneret. Bus stop (talk) 17:13, 15 November 2020 (UTC)

Thanks! I believe that answers it. I wanted to know if there was a fancy, ten-dollar, Greek word for it, but apparently there is none. I guess that kind of jargon went out of style years before spider behavior was given scientific attention. These days, arachnologists seem to use vernacular expressions interchangeably: "wrapping"; "curtaining"; "enswathing" (as you've said); "taping session" is something Barrantes and Eberhard said once in that paper. The closest thing to an official term for the silk-enclosed-mealwad seems to be "prey bundle", but "prey package" might be equally officiial. (In any case, I'm confident that it's not accurate to call it "a cocoon", which is what made me wonder: someone called it a cocoon, and I knew either they were kinda wrong, or I was absolutely wrong about how expansive the definition of "cocoon" was.). —Haikon 21:02, 15 November 2020 (UTC)

Units of values obtained bx XRF

Specifically, Table 4 in this sources gives some numerical values but it doesn't indicate what the value measures. Promille? Percent? ppm? Jo-Jo Eumerus (talk) 21:21, 15 November 2020 (UTC)

For trace elements the rock analysis is just about always ppm (of mass). See Table 2 for a clue about that. Only the major elements (oxides) are given by percent. Graeme Bartlett (talk) 21:35, 15 November 2020 (UTC)

27th Amendment

"No law, varying the compensation for the services of the Senators and Representatives, shall take effect, until an election of Representatives shall have intervened."

There exist a comment that this Amendment limits the pay raises given to the member of Congress. How does this statement (especially the last part I highlighted), limit the same? Thanks AboutFace 22 (talk) 22:09, 15 November 2020 (UTC)

The question does not call for a scientific reference. This article explains how this most recent amendement to the US Constitution was one of the earliest proposed, taking over 202 years to be ratified. It prevents elected representatives from changing their own salaries immediately they enter office. It appears that their permissible salary increase is limited to cost-of-living adjustments. 84.209.119.241 (talk) 22:45, 15 November 2020 (UTC)

I am surprised to see my post in the Science desk. I think I posted in Humanities. Thank you for the pointer. AboutFace 22 (talk) 23:33, 15 November 2020 (UTC)

You could move it to Humanities if you want. In any case, the point of the amendment is that they can raise their salaries, but it can't take effect until after an election. That way, if you don't approve of the raise, you can help vote the guy out of office. ←Baseball Bugs ^{What's up, Doc?} carrots→ 23:41, 15 November 2020 (UTC)

I have no idea how to move this post to another desk. Could you do it Bugs?

Edit this section, copy the text, post it in a new section on another desk, then come back here and replace the above with a comment that it's been moved to whatever desk. ←Baseball Bugs ^{What's up, Doc?} carrots→ 17:56, 17 November 2020 (UTC)

November 16

Thermodynamic force for synthesis of alkyl halides from alcohols

It's my fifth year of tutoring organic chemistry for the bread and yet something bugs me about the traditional explanations for synthesis of alkyl halides from alcohols. I'm a nontraditional premed / healthcare worker so I've always been more interested in the biochemical applications of organic chemistry rather than its industrial applications; nevertheless in my lessons I strongly emphasize "real life". Sometimes in the problem sets given by my students' professors where they have only learned how to use haloacids rather than say thionyl chloride or phosphorus tribromide (especially in abridged courses), I am forced to repeatedly re-explain why using haloacids work despite my discomfort.

It doesn't help that many of my students' professors set problems where the solvent is missing, the reaction conditions are missing and I do not know how the product is being distilled or how product is being removed. I also have never chlorinated or brominated an alcohol in the lab. Here is the thing that bugs me: carbon-halogen bonds are weaker than carbon-oxygen bonds. Why then is the formation of alkyl halides via SN2 more sluggish for chlorides versus bromides? The C-Cl bond is stronger than the C-Br bond. In polar aprotic solvent chloride should be a stronger nucleophile than bromide (if I am dissolving the alcohol in say carbon tetrachloride -- I suppose if one uses the alcohol as the solvent, sure). Thermodynamically, alcohols can be protonated but alkyl halides cannot. In addition, water as a leaving group can never deprotonate and re-form a hydroxide nucleophile. Hence, acidic conditions favor the alkyl halide but basic conditions favor the alcohol (ignoring elimination). Thermodynamically, how can I rationalize this?

Let's propose we chlorinate or brominate butanol:

• Primary R-OH: +110 kcal/mol
• Primary C-Cl: -85 kcal/mol (C-Br: -67 kcal/mol)
• H-OH: -110 kcal/mol
• H-Cl: +103 kcal/mol (H-Br: +87 kcal/mol)
• dH: +18 kcal/mol (+20 kcal/mol for bromination instead of chlorination)

I'm aware these are homolytic cleavage tables not heterolytic cleavage, but still Hess' law should still apply. I am not sure how this plays into the qualitative reversibility of the reaction (surely if the H-Cl bond is stronger than C-Cl, we should be able to protonate the C-Cl bond to allow for a reversible reaction?) What's the real answer? I am tired of undergraduate lies to children. Yanping Nora Soong (talk) 02:26, 16 November 2020 (UTC)

You are exactly right that you can propose a simple equilibrium of the overall reaction:

RCH₂–OH + H–Cl ⇌ RCH₂–Cl + H–OH

and think about the relative bond-strengths and microscopic reversibility and energetics of each step of the reaction mechanism.

Some thoughts that don't make a complete answer but do highlight some important ideas. The average bond-energy of a bond-type in a molecule is not the same as the bond dissociation energy of one such bond or if the substrate is quite different. The one that caught my eye was water. The average H–O energy in the H–O–H molecule is around –110 kcal/mol, but the first H–O bond losing one H) is around –119 kcal/mol. Similarly, I'm not sure the "pure" H–Cl bond-energy is relevant when one is considering protonating C–Cl (the Cl–H bond-strength is surely different in C–Cl⁺–H).

And as you note, there may be heterolytic differences--that introduces solvent effects and substantially different values in some cases. Those might not be important in a Hess's law cycle if you have really high temperature and lots of excess reagents (to overcome any activation barrier and don't have to worry about loss of reactant by secondary reaction with the product). And you also need a mechanism to get the reaction to work.

The easy way to rationalize when teaching is "in the given example, there are a ton of unstated variables. The fact that it does work means it's easy to pick variables that overcome (for example) reversibility. Therefore, the first step is to recognize even what could happen before designing an experiment to make it a likely high yield of what would happen." There is no one protocol that works for all substrates, and you can't start by teaching "every substrate is different, every product has different volatility and solubility, so let's learn every reaction as a practical example to optimize." POCl3 and SOCl2 are nice because their very nature drives the reaction so easily and you don't need to worry about equilibrium effects.

Regarding the Cl vs Br rate, there is the preliminary step of protonation of the alcohol prior to the S_N2 mechanistic step itself. If HBr is a stronger acid than HCl, then that first-step equilibrium shifts more towards products. How does that affect the rate of the two-step process? DMacks (talk) 04:33, 16 November 2020 (UTC)

So something I would point out to my students is that these reactions consume the acidic species (in the case of favoring the alkyl halide) or consume the basic species (in the case of favoring the alcohol), as distinct from the acid-catalyzed or base-catalyzed additions/substitutions they will later learn where the presence of water strongly must be accounted for (driven off/added). By a similar thermodynamic principle, water must be driven off to drive acid-catalyzed esterification to completion, but this is not required in saponification, which consumes the base rather than borrowing it for catalysis. So perhaps it is not C-X or C-OH bond strengths per se driving the reaction after all, but the chemical potential of the acidic or basic species? After all, the acidic species or the basic species are typically used in excess. In large enough excesses (1M or more), the activity coefficient of their chemical potentials would readily increase (opposite the Debye-Huckel trend for more dilute charges). By sliding the pH up and down, I alter the position of the equilibrium, which makes sense in part because water is a less reactive Bronsted-Lowry acid compared to HX but the alkyl halide is a more reactive Lewis acid than alcohol. Is this closer to a more enlightening approach?

The other issue is that in looking at BDE I am only looking at enthalpy rather than change in free energy. (It is a bit easier to teach changes in enthalpy than account for both dH and dS in an organic reaction in solvent.) In the dissociation of haloacids, dH is negative and dS is negative (which would be against intuitition from how I conceive of dissolving most solutes, were I not reminded that adding water to strong acid readily generates steam). Are there any worked examples for this particular case? It is such a basic topic in organic chemistry that I cannot seem to find suitably rigorous thermodynamic treatment for. I would like to follow the rigorous treatment myself so I can pick and choose which intuitive or qualitative explanations are best for a given situation (my students may not spontaneously ask to be "put through the rigors" but they often readily raise their own objections). Yanping Nora Soong (talk) 05:36, 16 November 2020 (UTC)

Where does the natural typical smell of urine come from?

Where does the natural typical smell of urine come from? (I'm not asking about the pathological smell, but the typical one the most of the people have it physiologically), which substance/es cause it? --ThePupil (talk) 08:44, 16 November 2020 (UTC)

You can find the answer in Wikipedia. See Urine#Odor.--Shantavira|^{feed me} 10:20, 16 November 2020 (UTC)

Actually, the querant cannot. That article section only talks about how the "normal" odor can be affected by disease or by the consumption of certain foodstuffs. It doesn't explain what gives rise to the "normal" odor in the first place.

Unfortunately, a cursory websearch only seems to find items which similarly offer explanations for "non-normal" odors, although some mention that ammonia is a contributor to the "normal" smell and can sometimes seem stronger than usual.

Perhaps a biochemist (for example) will notice this query and be able to give, or track down, an explanation, and perhaps even be willing to add the missing information to our article. {The poster formerly known as 87.81.230.195} 90.197.26.5 (talk) 11:49, 16 November 2020 (UTC)

(ec) That section only lists causes for atypical odours. A source I found is this rather old textbook, which describes the odour of "fresh normal urine" as being "due to the organic acids of the aromatic series".^[19] It is not immediately clear to me which group of acids this refers to; both the aromatic amino acids and the phenolic acids are both organic and aromatic. Uric acid belongs to neither of these groups. The textbook later mentions "aromatic ethyl-sulphuric acids" among the normal constituents of urine.^[20] Perhaps others more versed in organic chemistry can translate this into current terminology.  --Lambiam 12:15, 16 November 2020 (UTC)

Why does feces odor smell good if strength is low enough?

Sagittarian Milky Way (talk) 12:00, 16 November 2020 (UTC)

Which sense of "Why"?. One answer is, "by definition", provided we define the strength of the odour of faeces to be "low enough" if it smells good.  --Lambiam 12:43, 16 November 2020 (UTC)

Boiling sugar

I've found what look to be two contradictory statements, but I'm probably misunderstanding something.

• Thomas Telford: "Being a pioneer in the use of cast-iron for large scaled structures, Telford had to invent new techniques, such as using boiling sugar and lead as a sealant on the iron connections."
• Sucrose infobox: Melting point — "None; decomposes at 186 °C (367 °F; 459 K)"

How can one boil sugar if it doesn't even melt? This is the 18th century, so they probably didn't have convenient access to other kinds of sugars. Nyttend backup (talk) 18:54, 16 November 2020 (UTC)

• The statement in the Telford article about "using boiling sugar and lead as a sealant" is NOT in the citation at the end of the paragraph where you have the above quote. You are safe to remove the statement entirely with the edit summary "This statement is not in the citation at the end of the paragraph". --Jayron32 19:04, 16 November 2020 (UTC)

Ever made toffee? Sugar solution boils. One then dips Welsh flannel in it and uses this to caulk the joints. DuncanHill (talk) 19:07, 16 November 2020 (UTC)

That would be boiling sugar-water, though, not boiling sugar. --Trovatore (talk) 19:37, 16 November 2020 (UTC)

(e/c) "Boiling sugar" is perfectly normal English. DuncanHill (talk) 22:23, 16 November 2020 (UTC)

In the sense of sugar-water, really? Seems at the very least imprecise, and I'm not personally familiar with that usage. Could be a specialized usage in candy-making, maybe? --Trovatore (talk) 22:29, 16 November 2020 (UTC)

Perhaps this is a cultural difference. I grew up in a culture where making sweets, jam, preserves, etc was a normal part of life. DuncanHill (talk) 22:38, 16 November 2020 (UTC)

The sentence says "sugar and lead," so it already isn't just sugar... --OuroborosCobra (talk) 22:22, 16 November 2020 (UTC)

The sentence in the Thomas Telford was originally added by this edit with no cite. Our Pontcysyllte Aqueduct article says "Welsh flannel and a mixture of white lead and iron particles from boring waste", cited to a Royal Commission on the Ancient and Historical Monuments of Wales ref that states "a mixture documented to be of flannel, white lead and iron borings". So please update the Telford article and add the ref. DMacks (talk) 23:58, 16 November 2020 (UTC)

The claim of using sugar can also be sourced, e.g. from this Guardian article that predates the edit adding the claim to the article. Just a wild guess: perhaps Telford experimented not only with basic lead carbonate but also with lead acetate, another lead salt for which an old-fashioned^[21] name is lead sugar, and someone misinterpreted a phrase such as "a lead-sugar concoction" as denoting a mixture of lead and sugar, after which the error kept getting copied.  --Lambiam 10:32, 17 November 2020 (UTC)

A 1985 book source mentions "Welsh flannel and lead dipped in boiling sugar".^[22] There has to be some older, original source for this sweet story.  --Lambiam 11:05, 17 November 2020 (UTC)

Good find (and detail about old names)! DMacks (talk) 12:31, 17 November 2020 (UTC)

@DMacks: There's another, more precise comment about joints in the Pontcysyllte Aqueduct:

The joints were made watertight using welsh flannel dipped in boiling sugar, after which the joints were sealed with lead.

— Pontcysyllte Aqueduct in Science Photo Library, https://www.sciencephoto.com/media/174860/view/pontcysyllte-aqueduct

which seems to separate the lead's role from sugar. Alas, it's not sourced. --CiaPan (talk) 12:50, 17 November 2020 (UTC)

This says "a strange combination of Welsh flannel and a lead, iron and sugar concoction", this says "Welsh flannel and a mixture of white lead and iron particles from boring waste". Haven't found anything we could really use as a source yet, but a mixture of white lead, iron filings, and boiling sugar (pace those who have never made toffee) slathered over some good flannel could perhaps be viable. DuncanHill (talk) 13:14, 17 November 2020 (UTC)

Just for the record, as to what adding sugar to molten iron would have done, would be to create a crude form of steel. Sugar, a carbohydrate, is basically "carbon + water" and at those temperatures in a relatively low-oxygen environment, you would drive off water and be left with just carbon. Carbon + iron = steel, so I suspect the "boiling sugar (implied solution) added to the mixture or iron and lead would have formed some type of lead-steel-like alloy. Unless, of course, someone somewhere in the chain of misinterpretations has read misread something like "sugar of lead" or "sugared lead" or some such phrase which may have been lead sugar, which of course, contains no actual sugar. But those are only a few different possibilities, and unless we have the original source from Telford's own writing (rather than the nth-generation misreading of that source) it's still really hard to say. --Jayron32 13:45, 17 November 2020 (UTC)

And in today's "What's old is new again", 2007 patent "Production of Iron Using Environmentally-Benign or Renewable Reducing Agents". DMacks (talk) 20:30, 17 November 2020 (UTC)

November 17

Finding a reference cited on a Wikipedia page

Hello, I have been unable to find the reference Putty, Murali (2011). Pithomyces. 9. The Environmental Reporter. cited on the Pithomyces chartarum page. Can you help me source it please? Thanks, Vsuresh1 (talk) 04:44, 17 November 2020 (UTC)

I added a URL-link to the ref there. DMacks (talk) 05:08, 17 November 2020 (UTC)

How food protein passes into breast milk

Multiple studies (example) have shown that proteins from food mothers eat is present in breast milk, albeit in small quantities. Such proteins can cause sensitivity or allergic reactions in infants. However, my current understanding is that absent uncommon stomach lining or intestinal issues like ulcers, full proteins should not be able to pass from the digestive system into the blood. Proteins must first be broken down into their constituent amino acids before being absorbed into the blood. So, then, how could full proteins from food be present in breast milk shortly after consumption? Mamyles (talk) 02:24, 18 November 2020 (UTC)