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January 12

What's the explanation for late allergy discovering

Sometimes people find that they allergic for something in the late ages, for example to eat something, after they ate the same things for long time and they didn't have any noticeable problem with it. So my question basically is if an allergy to something starts late or it always there but it just increase with time? 93.126.116.89 (talk) 06:13, 12 January 2019 (UTC)[reply]

Allergy has general info about the subject. Googling "allergies developing later in life" yield a number of entries, such as this one.[1] ←Baseball Bugs ^{What's up, Doc?} carrots→ 07:03, 12 January 2019 (UTC)[reply]

Don't resort to Google for that; use PubMed. I tried adult onset allergies there, and a recent review sort of exists [2]; unfortunately it is paywalled to one of those journals you don't even have to look up if your library has because you know there's no chance of it. As a special favor to Nimur I won't tell you to use Sci-Hub, mostly because it grinds away for a while before getting a timed out message from the journal's own site. It wasn't one of their better days. But there are lots of other things on PubMed to read, like [3] which describes adults catching allergies, and (like children) often growing out of them. I encourage you to go further through the list and tailor the search to your specific research interests. Wnt (talk) 20:19, 12 January 2019 (UTC)[reply]

Can ferns be successfully grafted?

I've found plenty of literature regarding grafting gymnosperms and angiosperms but extremely little on grafting ferns. Is the lack of information due to ferns having an inability to be grafted? Or is possible to graft them, but it's just very rarely done? OrganoMetallurgy (talk) 19:24, 12 January 2019 (UTC)[reply]

According to this, "Formation of secondary PD (Plasmodesmata) is considered necessary for successful graft unions [...] grafting is indeed possible in ferns, indicating that, in spite of the absence of secondary PD in their tissues, ferns [...] can form secondary PD in special cases". However, these "special cases" do not seem to translate to common occurrence within horticultural practice, or rather, grafting with ferns is perhaps just so seldomly successful that it isn't attempted. The Royal Horticultural Society's Propagating Plants (ISBN 1405300612) has 5 pages devoted to ferns, and covers the following methods of propagation: sowing spores, planting bulbils, planting plantlets, simple division, division of rhizomes, propagation from stolons, propagation from auricles, layering, and separating offsets (tree ferns). No mention of grafting. Similarly, The Plant Lover's Guide to Ferns by Richie Steffen and Sue Olsen (ISBN 978-1-60469-474-1) states: "Gardeners can propagate ferns by three means: division, rooting bulbils, and sowing spore". Again, no grafting. PaleCloudedWhite (talk) 21:56, 12 January 2019 (UTC)[reply]

January 13

Human skin colour evolution

I dimly remember reading childish texts (a long time ago) that explained that black skin colour evolved to protect humans in hot climates.

However, if humans all came from Africa, presumably, we were originally all black and some [of what became] races eventually evolved lighter coloured skin. Except, I can't think of a survival mechanism that would make that work.

I'm well aware of the potential here for racist nonsense and trolling so references only please to where I might be able to read about this in reliable sources.

Thanks --Dweller (talk) Become old fashioned! 17:52, 13 January 2019 (UTC)[reply]

Probably doesn't answer your immediate question, but is on-topic: [4] Bazza (talk) 18:01, 13 January 2019 (UTC)[reply]

Vitamin D synthesis seems to have been a factor - see [5] and [6]. PaleCloudedWhite (talk) 18:19, 13 January 2019 (UTC)[reply]

I see we have articles for both Nina Jablonski and David Reich (geneticist). Martinevans123 (talk) 10:55, 14 January 2019 (UTC)[reply]

Note though this quote from the article "The paper doesn’t specify why these genes might have been under such strong selection. But the likely explanation for the pigmentation genes is to maximize vitamin D synthesis, said paleoanthropologist Nina Jablonski of Pennsylvania State University (Penn State), University Park, as she looked at the poster’s results at the meeting."

This raises the following issue. Vitamin D is used to make calcitriol which is involved in gene regulation. Evolutionary pressure to get the skin color changed in order to get more vitamin D in order to affect gene regulation, sounds strange as any suboptimal gene regulation can be modified directly. So, if the demand for more vitamin D synthesis did play a role, then that points to an advantage to have as strong seasonal vitamin D induced gene regulation variation where in winter time you would want to have low vitamin D levels and in the summer a higher level. Count Iblis (talk) 19:51, 13 January 2019 (UTC)[reply]

Being deficient in vitamin D potentially results in several deleterious effects on human health. PaleCloudedWhite (talk) 20:13, 13 January 2019 (UTC)[reply]

Yes, but this begs the question of why calcitriol is used for gene regulation in the first place. Count Iblis (talk) 20:55, 13 January 2019 (UTC)[reply]

As always with evolution, it's a mistake to look at things from an engineers perspective. Perhaps changes in ~~gene regulation~~the genes involved in biosynthesis would have had the same effect without a change in skin colour and it would have been as effective for things to happen that way, but that doesn't mean it should have happened that way. Evolution doesn't care how you got there, just that you did get there, if there was no evolutionary advantage to either pathway. And this isn't even a good engineers perspective since you can't just randomly decide it's suboptimal, I see no analysis of the changes required for either pathway to succeed, and the risks and costs of changes in these areas ~~has been~~ presented ~~so you can actually say one pathway is simpler/easier~~. (I'm not sure increasing biosynthesis rates is as simple as you seem to think. It's not like sun exposure is an arbitrary regulator. Instead it's a physical requirement for biosynthesis.) Besides, if we're looking at some reason for it to have happened via skin colour, rather then making up some reason for which AFAIK we have no evidence exists (an advantage to seasonal vitamin D), we should consider the possibility of sexual selection something it's generally accepted does occur, and which is believed to be one possible reason for the evolution of different hair colours and eye colours [7]. (In fact that mentions extreme skin depigmentation.) Besides of which, if we believe that there is an advantage to seasonal vitamin D regulation, we should consider why (AFAIK), there's no evidence it has evolved in some fashion in places where it's not possible to rely on significant seasonal sun exposure differences. Nil Einne (talk) 05:36, 14 January 2019 (UTC)[reply]

BTW, in the same vein you can't assume an alternative pathway for vitamin D biosynthesis should have arose that isn't so dependent on the sun. Although it sounds like there's no simple alternative pathway anyway Vitamin D#Biosynthesis, although not surprisingly the pathway we do use arose very long ago so it's probably a moot point. As to why we don't just produce it in abundance so that no one is ever deficient, well despite what the vitamin megadose people like to think, too much of something important can be harmful. And even before we get to the level of kidney damage etc Vitamin D#Effect of excess, it's a reasonable hypothesis that excessive amounts would be more harmful than beneficial. And that's before we even consider the costs of producing so much vitamin D. P.S. Clarified a few things in my original post when writing this. Nil Einne (talk) 10:52, 14 January 2019 (UTC)[reply]

Reading a bit more I realise I may have misunderstood something Count Iblis was trying to say, but most of my comments still stand. You can't assume genetic changes in another area could have happened which would have had the same effect and that there are simpler and so should have happened because that's simply not how evolution works. Especially when you haven't even demonstrated that the changes are more likely.

Notably, changes could easily have negative effects especially when there is also selective pressure in the same direction anyway. (E.g. changing the regulation system so that it's less depend on calcitriol could be a negative when there's also selective pressure towards increasing vitamin D production by lightening skin ton anyway.) To be fair, since it's likely you need a lot of changes you would probably expect some co-evolution of both until a reasonable balance is achieved provided either are reasonable changes. But no evidence has been presented this didn't happen anyway. (Note it's even possible that there were changes in regulation but because of the other advantages there were also changes in skin tone and eventually the changes in regulation went the other way.)

The fact that calcitriol is involved in regulation doesn't mean it's an arbitrary regulator. (Again, I don't know if the evidence is out there but Count Iblis has not presented it.) The article calcitriol and calcitriol receptor make me think that it could easily be an important physical component, in other words, you can't have the transcription factor without calcitriol or some alternative. This doesn't mean some other pathway wouldn't have worked, but like with the biosynthesis issue if for whatever reason it did evolve in this way, it's not going to magically change. And there could be so many reasons (likely more than one) why it evolved in this way, it doesn't have to be better than any alternative since again, we're talking about evolution not a super-engineer. It's not impossible that seasonal differences could be a factor, but then again, there's a very good chance this evolved where seasonal differences in sun exposure were minimal to whatever, perhaps single cell organism it first evolved in.

Ultimately of course, it's often not possible to be certain why something complex, especially something that happened a long time ago, evolved precisely the way it did.

Nil Einne (talk) 12:33, 15 January 2019 (UTC)[reply]

One has to consider the hundreds of millions of years that complex life has existed. During that time any problems with calcitriol having to be made from vitamin D which then requires enough UV radiation to reach the skin, would have had to be dealt with. This strongly suggests that it isn't actually a problem, rather a solution to a problem. So, low vitamin D levels causing gene regulation being modulated in a different way is not problem in the natural context, rather it is the intended optimal regulation. E.g. during very long periods of drought, animals may burrow underground for many months, vitamin D levels will go down and gene regulation is done differently. I'm then inclined to assume that this modulation in gene regulation isn't going to add to the problems of the animals, rather that it is going to help them survive. Or animals that have to survive in harsh winter conditions, their vitamin D levels will be lower too. I'm then inclined to assume that this lower vitamin D level helps such animals to make it through winter rather than making life for them even more difficult.

Vitamin D is also stored in body fat; animals in winter time who still have large fat reserves will have higher vitamin D levels than animals with smaller fat reserves. This suggests that low vitamin D is used by the body as a signal that energy supplies on the long term are not secure. To optimize survival probability then requires modulating processes such that less energy is used. This fits in well with a lot of the recent research results e.g. on how vitamin D levels modulate the immune system. Count Iblis (talk) 18:22, 17 January 2019 (UTC)[reply]

[Edit conflict] An excellent recent review is: Jablonski, N.G., Chaplin, G. 2017. The colours of humanity: the evolution of pigmentation in the human lineage. Philosophical Transactions of the Royal Society B 372:20160349. https://doi.org/10.1098/rstb.2016.0349 The article concludes that the advantage of dark skin is in reducing the photodegradation of folate; the advantage of light skin is an increased production of vitamin D, which is catalysed by UV light. The optimal balance between these opposing factors depends on ambient light intensity and thus on latitude. Jmchutchinson (talk) 18:29, 13 January 2019 (UTC)[reply]

I see. So a darker-skinned population that moved north would suffer increasingly from vitamin D deficiency and mutation of lighter skin would have made it more likely that their offspring survived to reproduce before the vitamin D deficiency killed them (or I suppose rendered them down the social order so they wouldn't get a mate)? --Dweller (talk) Become old fashioned! 22:07, 13 January 2019 (UTC)[reply]

You're right to think of black skin as ancestral. Note that dark skin coloration depends on a complex biology of melanocytes and melanosomes, with pseudopodia extended to regulate skin tanning on a week to week basis. The intricacy of these mechanisms speaks to the importance of protecting the skin, especially in ancestral African conditions. Apparently albino Africans not merely develop skin cancer, but develop it early enough for it to be a major cause of death. [8] Our article talks about a selective force to darken skin color 1.2 million years ago, but dark skin in primates has been around much longer than that. So the need to pigment skin is longstanding and has evolutionary mechanisms and distribution that indicate a deep evolutionary history, but there are selective forces at play to turn the regulation of the process up and down at much shorter intervals. It appears that light skin in Europeans and East Asians represents convergent evolution, presumably based on the inescapable realities of latitude. [9] Wnt (talk) 02:22, 14 January 2019 (UTC)[reply]

Since we now know that humans mixed with Neanderthals, why would this mixing not have led to us simply using the Neanderthal genes for pale skin? Count Iblis (talk) 04:24, 14 January 2019 (UTC)[reply]

Did Neanderthals have pale skin? --Jayron 32 13:21, 14 January 2019 (UTC)[reply]

It would seem so. From Neanderthal genetics#Interbreeding with modern humans:

"It is suggested that 20 percent of Neanderthal DNA survived in modern humans, notably expressed in the skin, hair and diseases of modern people.[14] Modern human genes involved in making keratin—the protein found in skin, hair, and nails—have specially high levels of Neanderthal DNA. For example, around 66% of East Asians contain the Neanderthal skin gene,[clarification needed] while 70% of Europeans possess the Neanderthal gene which affects skin colour. POU2F3 is found in around 66 percent of East Asians, while the Neanderthal version of BNC2, which affects skin color, among other traits, is found in 70 percent of Europeans."

{The poster formerly known as 87.81.230.195} 90.217.251.247 (talk) 19:23, 14 January 2019 (UTC)[reply]

That is related to Count Iblis' question but I think it provides minimal evidence towards Jayron32. The fact that many of those with paler skins have genes from Neanderthals which affect skin colour doesn't mean Neanderthal's had pale skin, it doesn't even mean the effect of these genes was paler skin. But my impression is it's generally believed they did, see e.g. Neanderthal. "A 2007 genetic study suggested some Neanderthals may have had red hair and blond hair, along with a light skin tone.[52]" Nil Einne (talk) 09:24, 15 January 2019 (UTC)[reply]

Yeah, my point was not to say that they didn't, it was to ask for evidence that they did. It's tautological to say that our evidence that Europeans got their pale skin from Neanderthal DNA is that Europeans have pale skin, and also have more Neanderthal DNA. That's a post hoc fallacy problem. Again, Neanderthal's may (or may not) have had pale skin, but you can't just drop a statement like that as though it were obvious and not have any clear evidence to back it up. It's not like saying "the sky is blue". I can't look at a Neanderthal today and see... All I wanted to know is "what is the evidence that they had pale skin" Nil Einne's last statement is the sort of thing I was looking for. That's a good start. --Jayron 32 14:08, 15 January 2019 (UTC)[reply]

January 14

Etymology of oxime

Our article on oxime doesn't say where the name comes from, and it is one of those rarely thought about functional groups that a person can get mixed up in their minds. Thinking about it, I would assume that the old nomenclature described at aldimine is the root of it, where the carbonyl is substituted with imine and optional side chain: our article has butyraldehyde -> butyraldehyde imine, acetaldehyde -> acetaldehyde N-methylimine as examples. Logically then, something like phosgene oxime could originate from "phosgene N-oxo imine" by the old nomenclature. I want to mention in our article then that oxime = N-oxo imine but I need a source for it and it isn't an easy thing to think how to search for. Can anyone point to a usable source (ideally, one we can access?). Note: this doesn't have to be the real historical etymology; it would be good enough to have a source to say that "this is the way you can remember it". Wnt (talk) 02:46, 14 January 2019 (UTC)[reply]

Well Wiktionary says it is a blend of oxygen and imide.[10] This is also supported by my Collins dictionary. oxygen + imide. Graeme Bartlett (talk) 02:59, 14 January 2019 (UTC)[reply]

The big Oxford Dictionary (Draft Third Edition entry of March 2005) says that it come from German oxim (oxy- + im- from imid imide). The first use of the German term seems to be V. Meyer & A. Janny 1882, in Berichte der Deutsch. Chem. Ges. 15 1324. Dbfirs 09:41, 14 January 2019 (UTC)[reply]

Mantises praying on birds and reptiles

How do praying mantises kill large prey such as birds and reptiles? I have seen videos of them capturing such prey and videos of them eating it, but I still cannot figure out how they kill such prey. Surtsicna (talk) 19:39, 14 January 2019 (UTC)[reply]

Mantises aren't venomous and it seems they kill prey by eating it. Their forelegs are powerful and equipped with spikes that can hold a prey item in position while the mantis eats it alive, often starting with the head first. According to this news piece on a recent study of bird-eating mantises, they are ambush predators that "strike out and grasp their unsuspecting meal with their two front legs, while holding onto a leaf or grass with their four back legs. Then, while their food is still alive, they begin their feast. There is no poison involved." PaleCloudedWhite (talk) 20:32, 14 January 2019 (UTC)[reply]

January 15

Science Nobel prizes.

So my question is on Nobel prizes to scientists that were not doing it of a university. Are there any Nobel prizes, that when 1st discovered, was by a corporation and therefore proprietary company secret, and then some years later, as their competitor companies started discovering it, then the 1st company decided to publish their recipes and later won a Nobel for it?

To give you an idea how proprietary companies are, just take a look at the paint industry in the U.S. We got large paint companies like Sherwin-Williams and PPG - no 2 paint companies make the same paint (except by coincidence). There was a 3rd company Valspar that died out, and 1 of the other 2 bought all that company's secret ingredients, and made it so they can only sell once.

Did anyone win a Nobel for rechargeable batteries? (Like for laptop and cell phone batteries.). Like 10 years ago, you had to recharge a battery when it was very empty to full, otherwise it would shorten the battery. Now, you can recharge a battery at 40% without hurting it as much. I think that was not any 1 company that discovered it, but a bunch around the same time.

Also 10+ years ago, the oil industry: the process of petroleum converted into gasoline, was done at around 35% efficiency. But today, it's done at almost 99% efficiency. Thankfully, it was not discovered by any private company, else they would have monopolized, so it was discovered by scientists for universities, so now all gasoline companies can do the same efficient process. But it doesn't seem anyone won a Nobel for that either. I wonder how much stuff in science is lacking due to some great discovery by a private company that made it proprietary so it'll be some years before someone else discovers it. 67.175.224.138 (talk) 04:09, 15 January 2019 (UTC).[reply]

The difference is what some history of science people call the difference between techne and episteme. If you want a good overview, check out the first episode of the recent Crash Course series by Hank Green on the History of Science. See here. Green uses terms like "techne" and "episteme", Greek words for what we might term "applied science" and "pure science" or "technology" and "research" because he wants to avoid the pejoritive distinctions we make between them. The basic idea is that science can be thought of as having two ends: to make more useful things (the techne) and to increase human knowledge (the episteme)). Almost always, the Nobel prizes in sciences like Chemistry and Physics tends to be awarded for advances in episteme science: science that advances knowledge, as opposed to science that lets us make things. Which is not to say that the one is more important than the other. Its just that techne science is not what those prizes are designed to award for. All of your examples are great, important scientific discoveries, but they are from the techne branch of science, which is usually outside of the scope of what the Nobel prizes are awarded for. --Jayron 32 14:03, 15 January 2019 (UTC)[reply]

One example that comes to mind is Shuji Nakamura, the inventor of the blue LED. He was an engineer at a Japanese company at the time, not a university researcher. ~Anachronist (talk) 04:51, 15 January 2019 (UTC)[reply]

Somewhat in between but there are also ones who worked for things like Bell Labs. Our article claims 9 prizes. You may find some of them listed here [11] but note that the affiliation is at the time of the announcement which tends to be long after the work which earned the prize hence why Shuji Nakamura is listed under University of California, Santa Barbara. Nil Einne (talk) 09:19, 15 January 2019 (UTC)[reply]

The Nobel science prizes in physics, chemistry, physiology and medicine are not rewards for patents, for commercialization or even leadership in these fields, and the award declarations do not contain recipes or design information that could constitute proprietary company secrets. According to Alfred Nobel's Will (seen here) that is interpreted by selection committees, the prizes go to persons whose work "during the preceding year" conferred the "greatest benefit on mankind". The committee interpretations have been controversial, tending to reward discoveries over inventions, sometimes overlooking significant team members (no more than 3 can share an award), sometimes awarding long after the relevant work e.g. Subrahmanyan Chandrasekhar shared the 1983 Physics Prize for his 1930s work on stellar structure and evolution (no posthumous prize is allowed), and a negative Nobel Prize effect has been observed about some prizewinners. Wikipedia has lists of Nobel laureates by country, university affiliation and secondary school affiliation. DroneB (talk) 13:57, 15 January 2019 (UTC)[reply]

Train bells

When are trains required to ring their bells? 2601:646:8A00:A0B3:0:0:0:ECBD (talk) 05:39, 15 January 2019 (UTC)[reply]

Depends on which railroad (what country's rules to follow). See for example General Code of Operating Rules and Northeast Operating Rules Advisory Committee for various parts of North America. DMacks (talk) 11:21, 15 January 2019 (UTC)[reply]

Generally slowly and for fairly long periods, as an indication "there is a train here". For more immediate signalling, they have whistles or air horns as well. These are louder, so can be heard from further away, and are more 'attention grabbing'. The use of bells is not universal (even 'common' would be doubtful) for railways internationally. They are common in the USA and the Mid-West, where railway lines were not enclosed by clear fences and level crossings are common. The rules have already been linked, and lines did vary, but generally they'd ring their bells when approaching the areas (crossings and unenclosed station yards) where the trains would be moving amongst traffic and the public.

In countries like the UK, railways have mostly been enclosed within their own fences and the public (including farm animals and road traffic) are kept away. Crossings are mostly made by bridges instead. If there is a level crossing in the UK, this would have had a crossing keeper staffing the crossing (automated today) and gates would be closed before the train. There are only a couple of UK locos with bells, fitted (along with headlights) after notable tours of the USA. Some of them were also the (rare) 'Toby the Tram Engine' types, which worked in the flat country of East Anglia, where crossings were common and bridges rare.

In Europe, main line trains were also segregated, although there were many examples of narrow gauge tramways (especially France and the Low Countries). These ran down a verge at the side of the road and often used tram engines, with enclosed running gear and bells. Andy Dingley (talk) 14:54, 15 January 2019 (UTC)[reply]

British trains use a two-tone hooter. Alansplodge (talk) 13:57, 17 January 2019 (UTC)[reply]

Same as most countries, British trains use a bell, where a bell is needed. If there is on-street running (i.e. a 'tramway') then British trains use bells. The whistles, horns or any hooters are used differently, for immediate signalling, not as a presence indicator. Andy Dingley (talk) 15:28, 17 January 2019 (UTC)[reply]

Claims of being the best

Paul Erdős: "Erdős published around 1,500 mathematical papers during his lifetime, a figure that remains unsurpassed." (quote taken from the respective article)

Leonhard Euler: "He is also widely considered to be the most prolific mathematician of all time. His collected works fill 60 to 80 quarto volumes, more than anybody in the field."

Two claims are contradictory to each other since there can only be one most. So who actually published the most? And if there is no way to compare, both statements should be deleted in each respective article. 14.169.111.184 (talk) 08:23, 15 January 2019 (UTC)[reply]

Presumably the difference is in total published work (books etc) vs published papers. There wouldn't really have been the culture of publishing papers in scientific journals in back in the days when Euler worked. 131.251.254.154 (talk) 08:56, 15 January 2019 (UTC)[reply]

Yes, the two claims are not directly comparable - the first is a statement of numbers (of a particular type of publication), the second is one of volume (publication type unspecified). More detail would be required for comparison. PaleCloudedWhite (talk) 09:14, 15 January 2019 (UTC)[reply]

Exactly as explained above. If person 1 writes 200 one-page papers, but person 2 has written 100 three-page papers, then the first person is more prolific in terms of number of papers written but person 2 is more prolific in terms of amount of text written. Both statements regarding Erdős and Euler are simultaneously correct, and do not contradict each other in any way. --Jayron 32 13:43, 15 January 2019 (UTC)[reply]

There's also two centuries between them. The format of scientific publishing had changed greatly in that period. Andy Dingley (talk) 11:10, 15 January 2019 (UTC)[reply]

Leinniz was before then even, and the project to publish all his work which started more than a hundred years ago is still ongoing. And Gauss is commonly counted as the greatest mathematician ever, have a look at List of things named after Carl Friedrich Gauss to get an idea of the extent of his influence. Dmcq (talk) 14:21, 15 January 2019 (UTC)[reply]

Comparing scientists on their sum of "intellectual property" (written papers, drawings, concepts) makes no sense. They all stand on their very own unique base. What to compare between Ferdinand Porsche, Nikola Tesla, Leonardo da Vinci, Albert Einstein or Srinivasa Ramanujan? They where all unique and awesome. --Kharon (talk) 23:28, 15 January 2019 (UTC)[reply]

It's interesting trivia. For a short time in the early 1990s I studied under Arnold L. Rheingold, who was at one point the most published chemist in history, though that may have been surpassed. It was a quirk of the field he worked in (X-ray crystallography), as an early crystallographer, he got a paper every time he worked out the structure of a molecule via X-ray crystallography, and he could crank those things out like once a week. No one gets papers published for that anymore, largely because of guys like Rheingold, who made it routine to get a crystallograph. It's true that volume of papers or number of pages of published text are not particularly good indicators of importance to one's field (however that would be quantified anyways), but Rheingold is not a particularly well-known chemist aside from that bit of trivia. --Jayron 32 15:23, 16 January 2019 (UTC)[reply]

Latex balloon additives

Rubber party balloons are often advertised as "100% latex", and thus safe for the environment. Yet they include pigments, and plasticisers, and possibly other additives. What are those chemicals, and what is their impact on the environment? Please give citations, as I want to add the answers to relevant articles.— Preceding unsigned comment added by Pigsonthewing (talk • contribs)

This article is quite detailed on the manufacturing process, though it glosses over a few things things that are highly variable, like specific pigments used in coloring the balloons. It may be hard, if not impossible, to list every possible pigment that has ever been used in a latex balloon, but other than that, it goes into just about every other ingredient, chemical, and process in making balloons. It's a good start for your research. This article lists the chemical make-up of many pigments used specifically in making balloons, but I don't think it's exhaustive. I hope those two articles help your research. --Jayron 32 13:36, 15 January 2019 (UTC)[reply]

January 16

Do people who get an orchiectomy tend to experience weight gain afterwards?

Also, is this experience different for people who got an orchiectomy and who go on testosterone HRT as opposed to going on estrogen HRT or not going on HRT at all? Futurist110 (talk) 02:16, 16 January 2019 (UTC)[reply]

You don’t say whether you are asking about an orchidectomy which has removed one or both testes. Having searched “weight gain after orchidectomy“ it seems that weight gain is a recognised after effect. I have been unable to find any quantative value for this so we can only assume that some people do and others don’t. If this is a personal issue then you really ought to talk to your family physician or surgeon about this. I hope this is a more helpful response than the previous poster. Richard Avery (talk) 11:24, 16 January 2019 (UTC)[reply]

Sorry, now I see that you are referring to a bilateral orchidectomy. Richard Avery (talk) 11:26, 16 January 2019 (UTC)[reply]

This article suggests that testosterone replacement therapy is commonly used to counteract unwanted side effects. Alansplodge (talk) 13:54, 17 January 2019 (UTC)[reply]

Sources on the inventor of the railroad switch

Dear Users, I am a user of Wikipedia in Italian, and I write mainly about the history of the railways

With another user I started the revision and integration of the item Scambio or Deviatoio, en Railroad switch.

In the course of my research I read in an Italian technical encyclopedia of the nineteenth century that the switch, as it is now used all over the world, invented by a certain Lorentz, that the consulted source defines "American" (in the Italian bibliography synonymous of "United States of America").

Here is the text: Questo è lo scambio adottato oggidì in tutta Europa e introdotto da non molto tempo negli Stati Uniti da Lorentz, che vi ha apposto il suo nome." Engl. transl: “This is the switch applied today throughout Europe and recently introduced in the United States by Lorentz, who has affixed his name to it.”

Source: C. Saviotti, Ferrovie, in Enciclopedia delle arti ed industrie, compilata colla direzione dell'ingegnere m.se Raffaele Pareto e del cav. ingegnere Giovanni Sacheri, Torino, UTET, 1882, vol. 3°, pages. 449-529; page. 487, § "Scambi", §§ "Scambio ad aghi".

So far I have not been able to find other sources to define who Lorentz was and when and under what circumstances he invented the switch.

Can you suggest to whom to ask or indicate me libraries, archives or scientific societies to ask?

Thank you so much.

Greetings from Italy, --Alessandro Crisafulli (talk) 11:36, 16 January 2019 (UTC)[reply]

At the inception of railways, sliding rails were used to connect one track to another [12]. These fell out of use after the patenting of an automatic switch [13]. These switches were already in use in America by 1846 [14]. See Railroad switch#History, where "Fox's patent switch" (1832) is mentioned. 2A00:23C2:2400:9600:399A:40EB:C465:27D3 (talk) 14:29, 16 January 2019 (UTC)[reply]

Wood, Nicholas (1825). A Practical Treatise on Rail-roads and Interior Communication in General. London:Knight & Lacey. would be one place to start looking. Andy Dingley (talk) 15:18, 16 January 2019 (UTC)[reply]

Jeanne Calment

There is some controversy regarding Jeanne Calment, about whether she really died at the age of 122, or if her daughter impersonated her (assumed her identity) for tax purposes. It was stated that the only way to resolve the question is through exhumation of both bodies. Assuming that they exhume both bodies, what exactly would this resolve? How would that resolve the question? I am assuming this might have something to do with DNA? If they do take DNA samples, would not that assume that "they" also have DNA samples from when both women were living, in order to conduct a comparison? And, if so, how likely/feasible is it, that they would actually have DNA samples "on file"? I am not sure how an exhumation will resolve the questions in this matter. Thanks. Joseph A. Spadaro (talk) 12:49, 16 January 2019 (UTC)[reply]

Can you provide a link to this so-called controversy? I would want to ask them, "How would the mother have died and been buried without anyone noticing it?" ←Baseball Bugs ^{What's up, Doc?} carrots→ 13:04, 16 January 2019 (UTC)[reply]

@Baseball Bugs: This is very common knowledge. Just check out the Jeanne Calment page and its Talk Page. Also, you can check out the List of the verified oldest people article -- and similar articles -- and their Talk Pages. This theory or hypothesis has caused quite the uproar, since the new year began. As to your question about "how would people not notice?" ... the simple answer is that it was supposedly a "scam" or a "fraud" -- and an illegal one, at that -- so the participants in the fraud pretty much kept mum. I found a detailed article that explained how this was quite feasible, even though it sounds implausible, at first blush. I will see if I can find the link to that article. Also, they did notice that "someone" died and was buried (obviously). But, authorities -- and the general folks, also -- were misled as to the identity of the person who had just died and was buried. Hence, the "scam" / fraud. All allegedly. Thanks. Joseph A. Spadaro (talk) 17:32, 16 January 2019 (UTC)[reply]

Here is one link: Jeanne Calment: the secret of longevity, by Nikolay Zak, Moscow, December 2018. I believe this is the research paper that started the whole controversy. Joseph A. Spadaro (talk) 17:57, 16 January 2019 (UTC)[reply]

Another link: J’Accuse…! Why Jeanne Calment’s 122-year old longevity record may be fake. This one explains how and why the fraud was perpetrated. Joseph A. Spadaro (talk) 18:26, 16 January 2019 (UTC)[reply]

Interesting hypothesis, with plenty of built-in assumptions. What I'm wondering now is, what would be the legal justification for an exhumation? Is France looking to get its tax money after 80-plus years? ←Baseball Bugs ^{What's up, Doc?} carrots→ 21:33, 16 January 2019 (UTC)[reply]

@Baseball Bugs: I dunno. Do they even need a "legal justification"? In the USA, anyone can exhume a body if, for example, they want to move the burial site. I am sure that France can -- if they want to and if they "need" to -- cite some law about fraud, or tax fraud, or tax evasion, or larceny, or lying to authorities, or falsification of government records, or what have you (etc.). It's unlikely, I think, that the French government would actually take this on, as a matter of PR (public relations), even if they would be "legally justified". Joseph A. Spadaro (talk) 04:36, 18 January 2019 (UTC)[reply]

Generally speaking in the US at least, there are laws regulating these matters, such as moving a body from one cemetery to another, for which a permit would be required. As far as doing something to the body itself, such as an autopsy, you would need permission and have a good reason, e.g. that there's a reasonable suspicion of a crime being involved. (Maybe you recall the brouhaha about exhuming and autopsying the body of President Zachary Taylor some years back, to find out whether he'd been poisoned.) ←Baseball Bugs ^{What's up, Doc?} carrots→ 05:48, 18 January 2019 (UTC)[reply]

Joseph, how does DNA relate to mother-daughter distinguishing?? One notable DNA that's the same in mothers and daughters is mitochondrial DNA. Yvonne and Jeanne have the same mitochondrial DNA, as does Jeanne Calment's mother. What DNA difference between Yvonne and Jeanne is there?? Georgia guy (talk) 14:28, 16 January 2019 (UTC)[reply]

I have no idea. That is why I came to ask this question on this page. I heard that "exhumation would resolve the issue", and I did not understand why or how. Hence, my question. My assumption about DNA was as follows: They had a sample of DNA from when the mother was alive. They had a sample of DNA from when the daughter was alive. After exhumation, they would take a sample from both decedents. And compare those (current) DNA samples with the "old" samples on file. And, hence, they can see which decedent "matched" which identity. But, I doubted that -- as a general rule -- deceased people have their DNA "on file" somewhere. But, who knows? It was the only thing I could think of. Joseph A. Spadaro (talk) 17:42, 16 January 2019 (UTC)[reply]

Presumably, because math works, there would be only be 50% of the nuclear DNA in common between Jeanne and her Mother. --Jayron 32 15:16, 16 January 2019 (UTC)[reply]

Can anyone explain exactly how?? Please include what statements P and Q are, defining them as follows:

If exhumation reveals statement P, then Jeanne Calment's longevity is real.
If exhumation reveals statement Q, then the November 2018 theory on Jeanne Calment is real.

Georgia guy (talk) 15:18, 16 January 2019 (UTC)[reply]

Possibly the issue that is being missed here is that there seems to be limited dispute that one is the mother and one is the daughter. The question is which is which. IMO it would be possible to distinguish to a high degree of confidence with sufficient coverage, but it would probably be far simpler to obtain the DNA of some other relative and use that as a guide. Nil Einne (talk) 15:56, 16 January 2019 (UTC)[reply]

If exhumation reveals that the body of Jeanne Calumet died on or about August 1997, then Jeanne Calment's longevity is real. If exhumation reveals that the body expired at a much earlier date, then the November 2018 theory on Jeanne Calment is real. This would be the realm of a forensic pathologist, who is trained in techniques to estimate time of death based on any number of tests they may do. --Jayron 32 17:09, 16 January 2019 (UTC)[reply]

@Jayron32: Doesn't your above reply miss the whole point? They exhume a body. How do they know if they are exhuming the mother or the daughter? Hence, how does exhumation resolve this question? Or, perhaps, I am missing something here? Joseph A. Spadaro (talk) 17:47, 16 January 2019 (UTC)[reply]

Yes that's what I'm trying to get at. AFAICT, the question here is not whether they are mother and daughter. It's which one is the mother and which one is the daughter of the two candidates. As I said I think it would probably be possible to decide with a high degree of confidence with significant coverage but IMO it would be far simpler to simply test another relative as well. I did have a look just now unfortunately this isn't easy to search at least it wasn't for me since you get a lot of basic and other stuff like differentiating between a sibling and child or siblings as parental candidates and of course basic stuff about parent - child DNA testing. Of course this sort of thing rarely arises. You're either doing geneogical testing or relationship testing etc. Even in forensic testing I imagine it's rare to not use something else. Nil Einne (talk) 19:01, 16 January 2019 (UTC)[reply]

Well, forensic pathology can also deduce age at death. If the body was of a 122 year old woman who has been in the ground for 22 years, it's her body. If it's something else, then it's something else. --Jayron 32 20:52, 16 January 2019 (UTC)[reply]

I missed the part about forensic pathology earlier but I find it doubtful we can reliably determine of someone is 122 or 99 not least because of the lack of good data. And remember that is the question not whether she is a 122 year old woman or something else very different. We would have a far better chance of differentiating a 59 year old and a 36 year old except that the remains could be fairly degraded. I still think of you're going to go to all the trouble of exhuming both mother/daughter and daughter/mother you'll be better off just finding some other sample. Especially since the daughter/mother body is likely to be fairly degraded for DNA too. This suggest the daughter/mother, father or husband, grandson or son and I presume now mother/daughter are all in the family tomb [15]. Note I'm not saying this should be done simply of were. Nil Einne (talk) 04:58, 17 January 2019 (UTC)[reply]

I had a quick look and found [16] I haven't read the article but the summary provides info which sort of tallies with my expectation and seems to IMO support my view that forensic pathology methods may not be sufficient:

The highest accuracy was in the 31-60 age category (74.7% with the 10-year range), and the skin seemed to be the most reliable age parameter (71.5% of accuracy when observed), while the face was considered most frequently, in 92.4% of cases. A simple formula with the general "mean of averages" in the range given by the observers and related standard deviations was then developed; the average values with standard deviations of 4.62 lead to age estimation with ranges of some 20 years that seem to be fairly reliable and suitable, sometimes in alignment with classic anthropological methods, in the age estimation of well-preserved corpses.

20 years may be slightly over the age differences, and of course we have an expected age to compare to. But considering the issues (very advance age for one, likely degraded remains for the other), I'm not convinced any conclusion would be sufficiently reliable. (Of course even if it is, I doubt that it will be accepted many of the doubters.)

I admit I forgot until now the fact we aren't talking about random unrelated individuals here but mother and daughter (related and for a chunk of their lives probably similar diets and to some extent lifestyles) could affect things. However I still expect considering the widely different death dates, and ages at time of death, it would be difficult to conclude solely from the pathology, which one was the mother and which one was the daughter. If they had both died on or around the same day sure you could probably say. But when one died in 1936 either at the age of ~36 or ~59 and the other died in 1997 either at the age of 122 or 99, well not so much.....

Nil Einne (talk) 11:31, 17 January 2019 (UTC)[reply]

Also, regarding the answer to your question "What DNA difference between Yvonne and Jeanne is there??", the answer I gave was that there would be only 50% in common between them. You asked "How?" The answer is that Yvonne Calment would have had two parents; Jeanne and her husband Fernand would be those two people. See, Geography guy, when a man and a woman love each other very much, and decide to make a baby, 50% of the nuclear DNA from each parent goes on to make the child. That's how Yvonne would share 50% of Jeanne's DNA. The article DNA profiling explains how this works in some more detail. --Jayron 32 17:14, 16 January 2019 (UTC)[reply]

This DNA-testing is irrelevant. They're not trying to prove whether the mother-daughter are related. The question is whether the daughter impersonated her mother after her mother's death. I have a picture of Jeanne Calment at age 60, if she were the mother then the year would be 1935. If the person of the photo were the daughter, then the year would be 1956. Maybe that's a start. Tell that to Ryoung122 and all those other affiliated. (Has it already been discussed before?) There is a mother-daughter pic in that French book about her life too. 12.239.13.143 (talk) 18:23, 16 January 2019 (UTC).[reply]

Apart form DNA-based methods, this method can also be used. Count Iblis (talk) 18:51, 16 January 2019 (UTC)[reply]

Interesting article, thanks. But the method only works for people born after the Cold War started. --76.69.46.228 (talk) 07:49, 17 January 2019 (UTC)[reply]

You know what, the Jeanne Calment confusion should be easily solved. Remember at the end of a Vincent Van Gogh documentary, a woman comes out says to be Jeanne Calment and mistakenly says her age by a little bit, which was 1956, where she allegedly 81. I think that and the other photo at age 60 - either 1935 or 1956, should easily prove whether the person is the mother or daughter, right? 12.239.13.143 (talk) 19:57, 16 January 2019 (UTC).[reply]

What do you mean by "says her age by a little bit"? ←Baseball Bugs ^{What's up, Doc?} carrots→ 21:11, 16 January 2019 (UTC)[reply]

Bah, at the end of the movie Lust for Life (film) the actor Kirk Douglas talks to random village women and 1 of them claims she met him in person and he asks her age. The whole thing is in French. However, someone commented in English that she didn't say her age of 81. Right now I can't find the video on YouTube or Google. But now I'm thinking, I'm relooking at the photo of mother and daughter and it seems the 60 year-old photo looks more like an aged version of the daughter than mother. Making me think the village woman at the end of the movie is someone else. Weird I can't find any discussion about it. 12.239.13.143 (talk) 21:40, 16 January 2019 (UTC).[reply]

Chromosomal crossover will occasionally cause parts of a father's chromosome to get interchanged with the mother's of a homologous pair. So, denoting a homologous pair of the mother as (A,B), the father's as (C, D), the daughter could inherit (A, C) but if a crossover happens A and C will have exchanged parts and have become (A', C'). If we have only (A, B) and (A', C') available, then we can see that A and A' are almost but not completely identical, that the parts of A that are missing in A' can be found back on C' but you can't find the parts of A' that are missing in A on B. Count Iblis (talk) 21:18, 16 January 2019 (UTC)[reply]

Thinking about this, there are easier ways to do this. We're thinking too hard. Wouldn't things like dental and medical records from prior to the date of contention (1934) help? If Jeanne, before that date, had dental work, of had missing teeth, or suffered an injury, or had certain diseases, those would be uniquely identifying markers on her remains that could help tell the difference between the two corpses. --Jayron 32 18:26, 17 January 2019 (UTC)[reply]

There should be a father in all this - if his DNA is known, then he will be closely related to the daughter but not (one hopes) the mother. Determining this from his distant relations (not descended from the mother) gets trickier, but because of genetic linkage a series of markers in a standard $99 sequence ought to clinch the case -- there will be sections of DNA with exactly the same alleles in one gene after another. Even if you can't do quite that (you get descendants of the father's brothers or something), there is so much information in DNA that you could work this out despite a lot of practical restrictions. More so if you have access to massive population databases of millions of people compiled for ~~identification for future surveillance~~ research by companies catering to ~~intelligence agencies~~ idle curiosity. Wnt (talk) 00:20, 19 January 2019 (UTC)[reply]

Engineering catalogs

In Junior High about a decade ago one of my nerd friends would bring us these thick, newsprint catalogs of science and engineering stuff. We’d drool over the Tesla coil kits, lasers that cut steel, etc.

Anyone else remember this? Know what it was called, or if they exist on the web? (Asking for an acquaintance) 68.229.214.195 (talk) 14:34, 16 January 2019 (UTC)[reply]

Would it have been something like Fisher Scientific? They are known for such catalogues. --Jayron 32 15:15, 16 January 2019 (UTC)[reply]

I'd have thought Edmund Scientific, if it's more at the gee-whizz end. Also ten years ago is pretty recent to still be on paper, not the web, and that sounds like Edmund. Andy Dingley (talk) 15:36, 16 January 2019 (UTC)[reply]

edmunds in closer, I got a date revision to the late 80s instead on 2008. Thanks, 68.229.214.195 (talk) 15:53, 16 January 2019 (UTC)[reply]

That long ago is into Whole Earth Catalog territory. Also there was more mil-surplus around back then, in many similar catalogues. One of the UK hobbyist electronic mags had a whole page ad running for years of plans and kits for psychoceramic science: anti-gravity, radionics, Kirlian photography. Andy Dingley (talk) 15:55, 16 January 2019 (UTC)[reply]

Something like this? They also have everything online. Just find a local offering trader for professional tools and check if they offer some catalogue in your language. --Kharon (talk) 22:28, 16 January 2019 (UTC)[reply]

January 17

Microscopy in the 17th century

The article Microscope states: "The microscope was still largely a novelty until the 1660s and 1670s when naturalists in Italy, the Netherlands and England began using them to study biology, both organisms and their ultrastructure." However, in Ultrastructure, it says: "Ultrastructure (or ultra-structure) is the architecture of cells and biomaterials that is visible at higher magnifications than found on a standard optical light microscope. This traditionally meant the resolution and magnification range of a conventional transmission electron microscope (TEM) when viewing biological specimens such as cells, tissue, or organs." But the TEM did not exist until 1931! So, can anybody help me resolve that apparent contradiction?--Hildeoc (talk) 19:49, 17 January 2019 (UTC)[reply]

Added in April 2017, unsourced. See Talk:Microscope/Archive 1#Request for comment on ultramicroscope (comments by the same IP too). I've removed it, as it's unsourced and implausible. Andy Dingley (talk) 20:03, 17 January 2019 (UTC)[reply]

@Andy Dingley: Thank you very much indeed!--Hildeoc (talk) 20:21, 17 January 2019 (UTC)[reply]

January 18

Inertia vs mass

What is the difference exactly between inertia and mass in the units in which they are expressed?. If the units are the same, are the quantities the same? 86.8.202.148 (talk) 00:40, 18 January 2019 (UTC)[reply]

Same dimensions, same units (kilograms), and same values. Yes, their quantities are the same.

They'd be the same for different gravitational fields too. That's not the case for weight, which varies according to the local gravity.

Inertia isn't the same thing as mass, but it is one of the physical manifestations of it, as inertial mass: the resistance of objects to an applied froce causing them to accelerate, per Newton's 2nd law. It's different as a concept from gravitational mass, see Mass#Inertial vs. gravitational mass, but the two have always been measured as equal, and (post-Newton) this has been given a theoretical basis as the equivalence principle. Andy Dingley (talk) 01:38, 18 January 2019 (UTC)[reply]

Ok. How can we price that inertia and mass are different things? — Preceding unsigned comment added by 86.8.202.148 (talk) 02:39, 18 January 2019 (UTC)[reply]

"Price"? ←Baseball Bugs ^{What's up, Doc?} carrots→ 03:58, 18 January 2019 (UTC)[reply]

I'm not quite sure what you mean. As Andy says, inertial mass is conceptually different from gravitational mass. The equality of inertial mass and gravitational mass is a synthetic rather than analytic proposition, one empirically observed to be true and for which we have good reason to think it should always be true, but it is not logically impossible that they could be different.

As far as contrasting "inertia" with mass — Andy seems to be taking inertia to mean inertial mass, but (as a linguistic rather than scientific point) I don't think that's correct. My understanding of the word "inertia" is that it describes a principle or a concept, not a quantity. You can't measure the inertia of something any more than you can measure the electromagnetism of something. So inertia doesn't have units. Again, this is a point about the meaning of the word, not about the deeper concepts. --Trovatore (talk) 04:13, 18 January 2019 (UTC)[reply]

Inertia and mass are different because we defined them to be different. They are just words after all, and we choose to apply them to concepts of our choice. There are three aspects to 'mass' – three fundamental physical behaviours that we observe. One of these we just call 'mass'. It's the behaviour that as atoms have mass, we can (with highschool physics and chemistry) sum that up to find molecular masses, then (with Avogadro's constant) bulk masses too. Tracking that further back to sub-atomic particles, we know that protons, neutrons etc. have mass, and that (with some atomic physics and the concept of binding energy) gives us those atomic masses. But going deeper than that is quite recent and into Higgs boson territory.

The other two aspects are empirical observations: we take a 'massive' particle and find that it has two distinct behaviours as a result. One is gravitational mass, i.e. the thing which gives rise to weight. Then it also has inertial mass, its resistance to acceleration. Recognising that those two are distinct, but consistently always the same value, is itself quite a deep insight, via the equivalence principle.

So really, your question is about "How are these three things related", not just two. Andy Dingley (talk) 10:34, 18 January 2019 (UTC)[reply]

Not sure what you mean by "my" question. Yes, there are three things involved, that's true. But none of the three is called simply "inertia". Inertia is not a quantity and does not have units. As I say, it's not a deep point, but it is a point. --Trovatore (talk) 22:18, 18 January 2019 (UTC)[reply]

Per Andy, who gave some excellent definitions, there's also something here to remember with regard to terminology. Inertia is a property of something's motion, specifically it is the effect of mass on momentum. The real question is why we have multiple different masses. Each kind of mass we measure in a different way. We have inertial mass which is mass we get by measuring the effect of that mass on changes in velocity, but we also have gravitational mass, which is we get by measuring the force of attraction between two bodies. Inertial mass comes from Newton's second law, whereas gravitational mass comes from Newton's law of gravitation. We also have rest mass and relativistic mass, which are the masses we measure when we are in the same or co-moving frame of reference as a body (rest mass) and when we are in a different frame of reference (relativistic mass). The real question is why measuring the effect of inertia on an object should be identical to measuring the effect of gravity on an object. Before Einstein, we only knew that careful measurements of both gave identical values, but we had no good theory to explain why those measurements were always the same. There was nothing at the time to predict that they should be the same; which is why we have two definitions. General relativity gave us the theoretical framework to explain why they had to be the same value. --Jayron 32 14:38, 18 January 2019 (UTC)[reply]

Do magnets attract flying sparks?

Does anyone have the answer or can they point me towards any videos or papers on this? I did a search expecting tons of cool videos showing sparks off a grinder being bent upward or attracted to a magnet, but drew blanks. I know heat can ruin the magnetism of iron, but can a strong enough magnet counteract that? ^Thanks,L3X1 ◊distænt write◊ 02:33, 18 January 2019 (UTC)[reply]

No. Iron/steel that is glowing red is above the curie temperature and thus stops being ferromagnetic. It is paramagnetic, but the forces involved are far weaker. --Guy Macon (talk) 04:57, 18 January 2019 (UTC)[reply]

Yes, magnets will do. This is familiar to any welder using magnetic clamps, and having to wipe dusty, ferrous crud off them.

The point about Curie point is a good one but the Curie temperature for iron is fairly high (it's typically a red heat). As sparks are small, they cool very quickly and will be below their Curie point within inches. If you have sparks that leave orange-yellow glowing trails, that's because they were hot enough to ignite and so they're not just hot as they fly, but they're actually still burning and maybe getting hotter (glowing sparks this hot aren't ferromagnetic, so aren't attracted to magnets). Some sparks even burst into bright fireworks, sometimes when they hit another surface. This is because they're hot, weakened by the heat and break up on impact or after time. This break up increases their surface area and so they burn suddenly brighter before going out. You can (to some extent) tell the alloy of unknown steel by spark testing it and looking at the shape and colour of these sparks. Some of these sparks (cast iron, wrought iron, some stainless) can indeed be magnetic as soon as they're formed. Andy Dingley (talk) 10:44, 18 January 2019 (UTC)[reply]

For reference, dark red heat is from 704°C to 814°C[17] and the Curie point of iron is 770°C.[18] So the OP wouldn't see the bright sparks from the grinder being attracted to the magnet, but the magnet would end up covered with the less-visible cooler bits of iron or steel. --Guy Macon (talk) 17:36, 18 January 2019 (UTC)[reply]

I had noticed that once and figured I was just not quick enough to spot anything, now I know I'd be unable to see those tiny pieces period as they were never sparks. Thanks all, ^Thanks,L3X1 ◊distænt write◊ 22:45, 18 January 2019 (UTC)[reply]

January 19

Surgical masks

The article says they stop others from getting sick if the wearer is sick. But, do they protect the wearer from sick people? Many thanks. Anna Frodesiak (talk) 04:53, 19 January 2019 (UTC)[reply]

Yes they do, by the same mechanism -- they filter out aerosol particles which carry viruses and harmful bacteria. 2601:646:8A00:A0B3:0:0:0:ECBD (talk) 04:57, 19 January 2019 (UTC)[reply]

Thank you! :) Anna Frodesiak (talk) 11:11, 19 January 2019 (UTC)[reply]

Preventing another Balvano

I've recently read the General Code of Operating Rules, and one of the things it says is that if a diesel train gets stuck in a tunnel, the crew must shut down the engine at once (to prevent carbon monoxide poisoning, obviously). Which raises the question, what is the emergency procedure if a steam train gets stuck in a tunnel??? Because that would be a dire emergency indeed -- a steam train generates far more carbon monoxide (along with other toxic gases) than a diesel train, and also I don't see any way that the smoke production can be shut down instantly! 2601:646:8A00:A0B3:0:0:0:ECBD (talk) 05:03, 19 January 2019 (UTC)[reply]

Armor Penetration

Hello, I wonder when I read about armor resistance against penetration, that for any type of armor, resistance against HEAT is greater than APFSDS. 46.32.122.165 (talk) 06:28, 19 January 2019 (UTC)[reply]

APFSDS = Armour-piercing fin-stabilized discarding sabot

HEAT = High-explosive anti-tank warhead

HEAT round technology dates from the 1940's German Panzerschreck and Panzerfaust that are fired at low velocity and rely on focusing the blast energy of their inner charge against a tank armour, see Monroe effect. HEAT warheads have since become less effective against tanks and other armored vehicles due to the use of composite armor, explosive-reactive armor, and active protection systems which destroy the HEAT warhead before it hits the tank. The APFSDS response is to launch at high velocity a long, thin round that maximises the kinetic energy in a smaller area. This development employs a rod of special deep-penetrating material such as Tungsten Heavy Alloy (WA) and Depleted Uranium Alloy (DU) and incurs a danger to nearby troops and vehicles from sabot petals that are discarded at high velocity. DroneB (talk) 13:33, 19 January 2019 (UTC)[reply]

So the penetrating rod is more resistant to lose its kinetic energy than the penetrating jet formed due to the melting of the copper cone inside HEAT warheads . 149.200.193.163 (talk) 14:03, 19 January 2019 (UTC)[reply]