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January 14[edit]

Etymology of oxime[edit]

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)

Well Wiktionary says it is a blend of oxygen and imide.[1] This is also supported by my Collins dictionary. oxygen + imide. Graeme Bartlett (talk) 02:59, 14 January 2019 (UTC)
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)

Mantises praying on birds and reptiles[edit]

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)

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)
See also this. Ruslik_Zero 20:41, 14 January 2019 (UTC)

January 15[edit]

Science Nobel prizes.[edit]

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. (talk) 04:09, 15 January 2019 (UTC).

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. --Jayron32 14:03, 15 January 2019 (UTC)
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)
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 [2] 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)
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)

Train bells[edit]

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

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)
King George V, still carrying the bell fitted for the US tour
  • 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)
British trains use a two-tone hooter. Alansplodge (talk) 13:57, 17 January 2019 (UTC)
  • 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)

Claims of being the best[edit]

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. (talk) 08:23, 15 January 2019 (UTC)

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. (talk) 08:56, 15 January 2019 (UTC)
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)
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. --Jayron32 13:43, 15 January 2019 (UTC)
  • 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)
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)
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)
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. --Jayron32 15:23, 16 January 2019 (UTC)

Latex balloon additives[edit]

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 (talkcontribs)

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. --Jayron32 13:36, 15 January 2019 (UTC)

January 16[edit]

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

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)

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)

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

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

Sources on the inventor of the railroad switch[edit]

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 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)

At the inception of railways, sliding rails were used to connect one track to another [3]. These fell out of use after the patenting of an automatic switch [4]. These switches were already in use in America by 1846 [5]. 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)
  • 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)

Jeanne Calment[edit]

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)

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)
@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)
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)
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)
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)
@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)
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)
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)
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)
Presumably, because math works, there would be only be 50% of the nuclear DNA in common between Jeanne and her Mother. --Jayron32 15:16, 16 January 2019 (UTC)
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)

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)
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. --Jayron32 17:09, 16 January 2019 (UTC)
@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)
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)
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. --Jayron32 20:52, 16 January 2019 (UTC)
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 [6]. Note I'm not saying this should be done simply of were. Nil Einne (talk) 04:58, 17 January 2019 (UTC)

I had a quick look and found [7] 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)

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. --Jayron32 17:14, 16 January 2019 (UTC)

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. (talk) 18:23, 16 January 2019 (UTC).

Apart form DNA-based methods, this method can also be used. Count Iblis (talk) 18:51, 16 January 2019 (UTC)
  • Interesting article, thanks. But the method only works for people born after the Cold War started. -- (talk) 07:49, 17 January 2019 (UTC)
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? (talk) 19:57, 16 January 2019 (UTC).
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)
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. (talk) 21:40, 16 January 2019 (UTC).
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)
  • 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. --Jayron32 18:26, 17 January 2019 (UTC)
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)

Engineering catalogs[edit]

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) (talk) 14:34, 16 January 2019 (UTC)

Would it have been something like Fisher Scientific? They are known for such catalogues. --Jayron32 15:15, 16 January 2019 (UTC)
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)
edmunds in closer, I got a date revision to the late 80s instead on 2008. Thanks, (talk) 15:53, 16 January 2019 (UTC)
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)
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)

January 17[edit]

Microscopy in the 17th century[edit]

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)

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

January 18[edit]

Inertia vs mass[edit]

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? (talk) 00:40, 18 January 2019 (UTC)

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)
Ok. How can we price that inertia and mass are different things? — Preceding unsigned comment added by (talk) 02:39, 18 January 2019 (UTC)
"Price"?Baseball Bugs What's up, Doc? carrots→ 03:58, 18 January 2019 (UTC)

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)
  • 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)
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)
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. --Jayron32 14:38, 18 January 2019 (UTC)
ok why not article say inertia is an inherent property of mass cos of Newtowns law. But does not exist without mass. In fact it's fictitious, like suction. Just another way of staring Isaacs laws. (talk) 23:32, 19 January 2019 (UTC)
I agree with Trovatore. Mass is a measurable quantity with units such as the kilogram. Inertia is a property that is possessed by all things with mass. A mosquito and an elephant both display the property of inertia but it isn’t correct to say the elephant has more inertia than the mosquito. The elephant has a much greater mass than the mosquito, and they both display inertia.
Newton’s first law of motion is often called the principle of inertia. It says if the resultant force acting on an object is zero, the momentum of the object remains constant. If the resultant force on an elephant is zero, the elephant’s momentum remains constant, but it isn’t any more or less constant than that of a mosquito which is experiencing a zero resultant force. Dolphin (t) 23:42, 21 January 2019 (UTC)

Do magnets attract flying sparks?[edit]

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)

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)
  • 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)
For reference, dark red heat is from 704°C to 814°C[8] and the Curie point of iron is 770°C.[9] 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)
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)

January 19[edit]

Surgical masks[edit]

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)

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)
Thank you! :) Anna Frodesiak (talk) 11:11, 19 January 2019 (UTC)
Careful. The article directly states - with a citation - "A surgical mask is not to be confused with a respirator and is not certified as such. Surgical masks are not designed to protect the wearer from inhaling airborne bacteria or virus particles and are less effective than respirators, which are designed for this purpose." Matt Deres (talk) 14:48, 21 January 2019 (UTC)
  • Not as much. A surgical mask is a layer of thin fabric and is effective against a spray of droplets (i.e. what's coming from the wearer's mouth and nose). However they're not effective against airborne fine particulates, such as bacteria or viruses. The risk of infection from a patient is usually lower than the risk of infecting a patient (for conditions which aren't spraying fluids everywhere, and ignoring the fack that patients tend to be more ill), which is why the facemask was so generally worn.
If a medic wants to avoid an infection themselves, they're more likely to wear a clear plastic face shield than just a mask. Andy Dingley (talk) 15:05, 21 January 2019 (UTC)

I planned to write a better answer but to be honest, I can't really be bothered digging up the sources. As others have said and others mentioned, it's unclear whether face masks provide any real protection to the wearer again aerosolised viruses. They do provide some protection from the wearer coughing and sneezing.

For example, for control of season influenza, in healthcare settings the US CDC recommends they be worn by possibly infected persons until they are isolated. They also recommend either a surgical mask, or a respirator "when antiviral medication supplies are expected to be limited and influenza vaccine is not available, e.g., during a pandemic", for healthcare workers getting within 6 feet of a person who is infected or likely infected. This is along with standard and droplet precautions which I think will generally include eye protection (either goggles or a face shield [10]) They recommend infected people wear a mask in some circumstances. Outside healthcare settings, they make no recommendations for mask use, even for people who are unvaccinated and at high risk of complications. (They do suggest if they are going to wear a mask they should do it all the time.) [11]

During the 2009 H1N1 pandemic, they did recommend a face mask or respirator for those at high risk of complications where H1N1 was presented in the community in crowded settings and for caregivers of those infected. (They also said they weren't recommended could be considered by those both high risk and not high risk in non healthcare occupational settings where people were coming into with those with symptoms.) BTW, the guidelines also suggests that although there is agreement that respirators are better, it's not clear if this applies if they don't fit properly or aren't used properly. (Maybe see also [12] and the earlier CDC guidelines PDF which does note there seemed to be no differences in Hong Kong during the SARS outbreak.) I think this is one reason why they were mentioned together. (For healthcare workers, you also have to consider time taken etc and how these affect compliance rates and other issues.) [13].

It's my understanding that even for those who suspect they may be of benefit when used by non infected persons who aren't knowingly coming into close contact with infected persons, one of the biggest hypothesis advantages is actually in limiting them touching their faces. [14] [15]

Nil Einne (talk) 04:55, 22 January 2019 (UTC)

Actually I noticed that our article does mention and link to [16] which seems to be a WP:MEDRS compliant source. I do not have access to the full article but the abstract does say "Of the nine trials of facemasks identified in community settings, in all but one, facemasks were used for respiratory protection of well people. They found that facemasks and facemasks plus hand hygiene may prevent infection in community settings, subject to early use and compliance." So it's possible there is now evidence they are useful for non infected people in certain circumstances. That said, we still don't know why are are of use. Nil Einne (talk) 05:21, 22 January 2019 (UTC)

Preventing another Balvano[edit]

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)

Over 500 people died in a coal-burning freight train in the 1944 Italian Balvano train disaster from carbon monoxide poisoning during a protracted stall in a tunnel. Preventive regulations were subsequently enforced and were repealed in 1996 when the line was electrified. It is difficult and dangerous to shut down a steam boiler rapidly e.g. by dousing the grate with boiler water. DroneB (talk) 14:07, 19 January 2019 (UTC)
  • It depends a lot on the tunnel. Some tunnels are better ventilated than others, some even have mechanical forced ventilation by fans. Also the exhaust from a loco depends enormously on how hard the loco is working at the time. As well as Balvano, a similar accident had happened a little earlier at the Swan View Tunnel in Australia, although in that case a purely freight train was affected and so there were only the two engine crews. These cases are rare though: in all the ones I know of, they're the combination of a single track tunnel, a steep uphill gradient, heavy trains, slow movement (at best) and the train stalling or slowing right down. There are many cases though, especially in the 1890s, where particular tunnels were known to leave engine crews 'half choked' as a matter of regular occurrence (although not measured at the time, many tunnels, such as Swan View, were later measured at increasing crews' blood carbon monoxide levels "by 10%" [17] (I have no idea what that means, as baseline CO levels should be near enough zero). Several of these tunnels were early targets for the replacement of steam haulage, although this was done by electric locomotives, not diesel (electric locos appeared 30 years before diesels). Newcastle Quayside's infamous horseshoe tunnel gave rise to the ES1 electric locos. Baltimore's Howard Street Tunnel of 1902 and New York's S-Motors of 1904 were early electrification schemes for approach tunnels to large urban terminii, after the Park Avenue Tunnel accident, caused by poor visibility from steam locos obscuring signals.
In some cases though, steam locos can stop in a tunnel without problems. During WWII, a train heading to South Wales was strafed by enemy aircraft and 'hid' in the Severn Tunnel for some time. There were no problems of suffocation, as this tunnel is double track, ventilated by a large fan at Sudbrook, and although the loco had been working hard (at excessive speed) to reach the tunnel, its fire could be quietened down somewhat once within it, as the train stopped.
The greatest risk in tunnels though is fire. In the confined space, escape is difficult and the fire is usually left to burn itself out. The Summit Tunnel fire and the shorter but equally fierce Howard Street Tunnel fire are good examples. Only in cases like the 1996 and 2008 Channel Tunnel fires can such fires really be fought, as there is an isolated service tunnel giving access.
Diesel locomotives (unlike petrol engines) generate carbon dioxide rather than carbon monoxide. This is still an asphyxiant, but not toxic as the monoxide is, and so the fume hazard is much lower. Again, we're back to the question of the tunnel. It's not a big problem for the train to stop in the tunnel and to shut down the engine, a greater risk would be the locomotive was still moving slowly and working hard uphill. Diesels do need ventilation though; the Cascade Tunnel was built for steam and had such problems working uphill that the trains had to be spaced much further apart in one direction than the other. Very soon it was another site for early electrification, just to avoid this. The whole tunnel was eventually relocated (to reduce the effects of bad weather) and the new electric tunnel was much longer. When that tunnel was dieselised in the 1950s, electric ventilation fans (1,600 bhp, the size of a small diesel locomotive) had to be fitted.
To the original question though, steam locomotives are recognised to rarely 'break down' as diesels can do. Even diesels rarely stop dead in one place, and so crews of either type would generally make great efforts to at least reach the end of the tunnel (and wouldn't enter it with a failing engine). The greater risk is when they struggle through the tunnel slowly, with the engine working flat out. There are fewer failures for a steam loco which stop it dead on the spot, and most of those would count as "accidents", bringing their own problems and likely injury. If a steam loco was stopped though, it's possible to reduce the strength of the fire fairly quickly (the fire does respond to the load on the engine, owing to the draughting effects of the blastpipe). 'Dropping the fire' would be the usual next step, throwing the burning coal onto the ground and away from the firebox and boiler. This is normally done in a situation such as when the boiler is about to overheat through lack of water, and it still leaves the fire burning. It would be possible to quench the fire (steam locomotives have plenty of water handy), but the risk then is that quenching the fire produces water gas, much as some old forms of gasworks produced, and that's mostly carbon monoxide! It's a fire risk too.
So, in general, the advice has always been 'keep moving'. But in a handful of excessive causes, that led to accidents such as Swan View and Balvano. Andy Dingley (talk) 14:41, 19 January 2019 (UTC)
So, in general, what would be the right course of action if a steam train, working hard, stalled in a tunnel on a steep uphill grade (same situation as Balvano): (1) shovel on more coal, build up as much steam as possible, sand the rails if need be, put the reverser full forward, and try to get going uphill again; (2) put the engine in full reverse, open the throttle and back out of the tunnel; or (3) drop the fire, set the handbrakes, and tell the pax to run for their lives? (And if (3), should the pax evacuate uphill, past the engine, or downhill away from the engine?) 2601:646:8A00:A0B3:0:0:0:ECBD (talk) 08:49, 20 January 2019 (UTC)
  • The right course of action is to not get into that situation. So run trains with adequate motive power for the load and gradient. Limit the size of trains going through such tunnels. Double head them with two locos. Double head with a diesel loco as well as steam. Design cab-forward locos, such as the Southern Pacific class AC-12, for use in such tunnels. Provide oxygen masks (either regular or emergency) for the crews.
These were very rare accidents. They happened during pressured times (the two here were both wartime) when trains were overloaded and motive power in poor condition.
Certainly the idea of rolling back downhill has been used in some cases, but that would have to depend on the driver and where in the tunnel they were. Andy Dingley (talk) 11:01, 20 January 2019 (UTC)

Armor Penetration[edit]

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

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)
Ahem, I think you'll find that the British PIAT was a squeak earlier than those German contraptions, a creation of Winston Churchill's Toyshop. The actual charge was invented in Switzerland by Henry Mohaupt before the war, but making it fly through the air was a challenge for both sides. Alansplodge (talk) 17:41, 20 January 2019 (UTC)
Robert H. Goddard and Clarence N. Hickman demonstrated a man-portable rocket-powered antitank weapon to the US Army Signal Corps on November 6, 1918, following which peace broke out which delayed Hickman's development and fielding of the Bazooka illustrated until 1941. DroneB (talk) 20:13, 20 January 2019 (UTC)

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 . (talk) 14:03, 19 January 2019 (UTC)

The HEAT warhead works only if it detonates at exactly the right distance while the APFSDS can be made as long, as thin (aerodynamic) and as fast as you like. DroneB (talk) 14:13, 19 January 2019 (UTC)
  • Yes. Resistance against HEAT is greater than APFSDS. This is because HEAT is 40 years older, and armour was then developed to resist it. APFSDS was then developed to defeat that improved armour. It's the classic arms race, where each weapon promotes a defence against it, and each defence promotes a new weapon to defeat it. Andy Dingley (talk) 14:43, 19 January 2019 (UTC)
I wouldn't be that general. Against passive hardened steel armour, HEAT is very effective - and indeed, I think more effective than APFSDS fired with the same muzzle energy. It's less effective against active armour technologies. But the advantage of APFSDS comes at the cost of a much more powerful launch system. Nearly all man-portable weapons effective against post WW2 tanks are HEAT. --Stephan Schulz (talk) 16:28, 20 January 2019 (UTC)
HEAT can be counteracted by spaced armour and slat armour. Alansplodge (talk) 17:41, 20 January 2019 (UTC)
Yes, APFSFS is more foolproof if you can bring it to the battle, althought there are things like tandem-charges and even tripple charges to compensate for some of HEATs weaknesses. But the main problem is that a typical APDSFS delivery system as e.g. the Rheinmetall Rh-120 weights 4.5 tons (without carrier vehicle). A typical HEAT delivery system is the RPG-7 at about 7kg. The very best APDSFS system can be defeated by not being at the battle due to logistic difficulties. --Stephan Schulz (talk) 09:19, 21 January 2019 (UTC)

Thanks alot everyone. (talk) 21:49, 20 January 2019 (UTC)

Just a note about the caption on the right; the 1918 rocket launcher lacked an effective warhead against tanks (even 1918 ones). It was not until the US produced the M10 shaped charge anti-tank grenade in the spring of 1942, that Leslie Skinner and David Uhl were able to put rocket, launcher and grenade together. The first prototype (made from a piece of scrap tubing with a wire coat-hanger for sights) wasn't demonstrated until May 1942. See There's a War to Be Won: The United States Army in World War II by Geoffrey Perret. Alansplodge (talk) 19:20, 21 January 2019 (UTC)

Enthalpy vs. internal energy: potential mistake in article[edit]

Our article standard enthalpy of reaction currently states:

From the first law of thermodynamics we have a relation,

That is, the enthalpy of a reaction at constant volume is equal to the change in the internal energy (Δ E) of the reacting system.

I will readily admit that is one topic where I get confused all the time, but I believe this is incorrect. The first law at constant volume says the change in internal energy is equal to the heat transfer. The standard enthalpy of reaction is defined by the heat of reaction at constant pressure (since it is for everything at standard T/P), but the heat of reaction at constant pressure is not necessarily the same as the heat of reaction at constant volume, is it? TigraanClick here to contact me 19:33, 19 January 2019 (UTC)

They differ by the work performed to change the volume i.e. by . Ruslik_Zero 20:51, 19 January 2019 (UTC)

A mundane web search says constant pressure of 1 atm, one bar and a specified temperature, 1 atm, 25 C, usual phase for STP, or 1 M in solution. It might be productive to keep looking, because I just took the top university-looking hits, but I think the OP has the right of it and can cite any of these or some other to make the change suggested. Just intuitively ... the other definition supposes, for example, that the enthalpy change of running a furnace reflects the heat produced when you dispose the exhaust from the furnace as high pressure CO2 and water, which might be ecologically friendly but doesn't seem very common. Wnt (talk) 22:07, 19 January 2019 (UTC)

Heat added to (or subtracted from) a solid, a liquid or a gas at constant volume is equal to the change in internal energy. Heat added to (or subtracted from) a gas at constant pressure is equal to the change in enthalpy. Dolphin (t) 06:06, 22 January 2019 (UTC)

at witch pressure morphes air to a state that looks like steam ?[edit]

I just want to know at wich pressure air morphes into a state where it is compressed so much that it looks like steam — Preceding unsigned comment added by Saludacymbals (talkcontribs) 20:26, 19 January 2019 (UTC)

well pure steam looks like air. Do you mean condensed steam that looks like a cloud? This depends on the humidity and whether the compression is adiabatic. If you compress the air and remove the extra heat to bring it back to the same temperature, the condensation will be inversely proportional to humidity. So if humidity is 50%, you will have to compress by a factor of 2. If humidity is 90%, then the volume only has to be reduced to 90% of the original, ie compress by 100/90 or 1.11111.. to make fog. If you compress the air fast, there is no time for heat to be removed and the air holds more water vapour, and it does not cloud up at all. Instead the air has to be expanded or decompressed to cool it so that cloud condensation occurs, that is how clouds are produced. If you compress air by an extremely huge amount it (nitrogen, oxygen, argon) will not liquify, as it is supercritical but at some pressure it will solidify. Graeme Bartlett (talk) 22:05, 19 January 2019 (UTC)

no i meeant this: and this : in both videos you can see that air pressure can be so high that the air somehow solidifies and i wonder at wich pressure this occures — Preceding unsigned comment added by Saludacymbals (talkcontribs) 00:20, 20 January 2019 (UTC)

Well that first video shows burnouts (burning rubber) and airborne dust, no compressed air visible. The second video shows compressed air driving a turbine. Where you see the condensation that would be due to adiabatic cooling. The air escaping from the turbo is close to atmospheric pressure, but is colder, cold enough to condense water vapour to fog. Graeme Bartlett (talk) 03:04, 20 January 2019 (UTC)


Why is it that sources will say chimpazees and humans share 98% of DNA and all humans share 99.7% of DNA, but two non-identical human siblings share 50% of their DNA? TFD (talk) 22:47, 19 January 2019 (UTC)

It's because, depending on context, those sources are comparing different things.
Taking the numbers in your question as being approximately correct, if you sequence the DNA of a chimp and a human and then line up those sequences side by side, 98% of the letters (nucleotide bases: a, c, g, t) in each of those lined-up sequences will match. (I'm not going to get into the precise details of what gets lined up, and the difference between expressed genes and introns, and so forth; we're just going after the general idea.) If you sequence the DNA of two random humans, they'll match up in 99.7% of those letters.
All of human genetic variation, then, is due to those minute differences in that last 0.3%. (I'm again ignoring some ifs, buts, and other assorted approximations, and will continue to do so without additional disclaimers.) So where does the 50% figure come from? It comes from the fact that each child gets 50% of their DNA sequence from Mom, and 50% from Dad. So if you sequence the DNA of Child One and line it up with Mom's DNA, you'll find that most of it lines up pretty well (remember, any two random humans are within about 0.3%), but 50% of it matches exactly. Same thing when comparing Child One and Dad—pretty good matches all the way along, but 50% is exactly the same.
Now when we look at Child Two, they also get 50% Mom DNA and 50% Dad DNA—but it's a random assortment. Child Two isn't likely to have gotten the exact same 50% of Mom's DNA, or the exact same 50% of Dad's DNA. On average, though, Child One and Child Two get exact duplicates of the same 50% of their parents' genetic material: 25% of Mom's DNA (50% of 50%) plus 25% of Dad's DNA. So Child One and Child Two will have DNA that lines up very well all the way along – they're both human – but along about 50% of their DNA they'll match perfectly. TenOfAllTrades(talk) 01:50, 20 January 2019 (UTC)
Thanks. TFD (talk) 04:50, 20 January 2019 (UTC)
Other articles to read are identical by descent, coefficient of relatedness, and Hamilton's rule. The 50% figure for full sibs is the coefficient of relatedness, which enables us to predict/understand when selection will favour helping kin at some cost to the donor. Jmchutchinson (talk) 22:01, 20 January 2019 (UTC)

January 20[edit]

Phenomenal eggs[edit]

What explains the following phenomenon:

Fill a basket about halfway with straw, add a few eggs, fill the rest of the way with straw such that the eggs are approximately in the center of a basket of straw. Now, shake the basket. One would expect the eggs, being much heavier (denser) than the straw would "gravitate" to the bottom of the basket; however, they rise to the top instead.

I came across this in a real-life experience and remembered the above phenomenon from one of my prehistoric science classes, but forgot the explanation. —2606:A000:1126:28D:20D1:2886:5F71:22E5 (talk) 15:45, 20 January 2019 (UTC)

This is probably a size-based packing, more than density. If the density difference is fairly small (try it again with stone eggs), then what happens instead is that small perturbations from shaking allow the smaller particles to drop, but not the big ones (they're always supported by something). There's a similar effect for why fields continue to "grow rocks", even after farmers have taken all the rocks out. Andy Dingley (talk) 16:03, 20 January 2019 (UTC)
We have an article about this. catslash (talk) 17:15, 20 January 2019 (UTC)
Face-smile.svg Thank you  "Granular convection" is the term I was looking for (is straw 'granular'?). BTW, the "real-life experience" was an effort to get grapes to stay at the bottom of a container of tobacco (they magically keep rising). —[OP]: (talk) 19:13, 20 January 2019 (UTC)
The phenomenom of the heavy eggs rising appears to represent extraction of energy from a field of particles in random motion, something which is argued by Feynman to be impossible in a Brownian ratchet. DroneB (talk) 19:51, 20 January 2019 (UTC)
You have to put energy into the container to get the eggs to rise. Greglocock (talk) 21:00, 20 January 2019 (UTC)

OK. I just have to ask. Why would anyone want grapes to stay at the bottom of a container of tobacco? --Guy Macon (talk) 22:29, 20 January 2019 (UTC)

Grapes have a natural means of maintaining an even humidity (absorbs moisture if above a certain level; emit moisture if below a certain level). They also add a bit of aroma, since the tobacco absorbs aroma. The tobacco has anti-fungal properties so the grapes will not rot; instead, they'll eventually turn into raisins —if— they stay covered (not directly on top; ie: not exposed to ambient air). [sorry, no citation]2606:A000:1126:28D:20D1:2886:5F71:22E5 (talk) 23:05, 20 January 2019 (UTC) —P.s: raisins soaked in cognac turn into yummy grapes.[18][19]
The failure of the Brownian ratchet does not imply the failure of all ratchets. It does mean that the pawl must be damped - it must be able to lose the energy given to it be the teeth rather than return it to them. Although the motion of the granules is random, it is damped by friction, and in this it differs from the motion of the atomic particles in the Brownian ratchet. This is a corollary Greglocock's observation that you must put energy into the system. The ratchet mechanism may or may not be the true explanation of the Brazil nut effect, but it is at least a possibility. catslash (talk) 23:52, 20 January 2019 (UTC)

Emotions with a cognitive component[edit]

Certain emotions e.g. joy, sadness do not seem to necessitate a "cognitive", or "propositional" (I think that's right) component to them: they don't have to be "about" anything. However, others, such as anger or surprise, seem to.

  1. What does this say about the status of anger and/or surprise as emotions? Are they not basic emotions, or are they?
  2. Presumably both emotions have moderately distinctive involuntary physiological effects that can be altered with drugs. How do these drugs affects other aspects of anger and/or surprise?--Leon (talk) 16:39, 20 January 2019 (UTC)
OR, but I have experienced lingering annoyance without being able to recollect what I was annoyed about - suggesting that this emotion can exist separately from cognition. catslash (talk) 23:15, 20 January 2019 (UTC)
As a counter example to "anger needs cognition" consider the Hatfield–McCoy feud and Von Hippel–Lindau disease#Notable cases. Imagine living nextdoor to people who suddenly get angry for no reason. --Digrpat (talk) 22:36, 21 January 2019 (UTC)

Looking for something about Isolation Experiments on people[edit]

I didn't see anything about this on the solitary confinement page. I just want to know if there's any data about individuals being isolated and how long they lasted before they experienced any mental issues. Sensory deprivation studies would be the extreme version of what I see.. I'm just looking for data in regards to solitary confinement with little sensory input. (talk) 18:05, 20 January 2019 (UTC)

Besides the article Solitary confinement, Wikipedia has articles about Solitary confinement of women and of the mentally ill in USA. There is also an article about Sensory deprivation. The Ganzfeld effect of perceptual deprivation or the use of sensory deprivation in the Ganzfeld experiment in ESP may be of interest. The cited articles contain many references. There is also a report on hallucinations in sensory deprivation that follows a study in 2009. In the '50s Donald Hebb at Montreal's McGill University studied how sensory isolation affects human cognition. DroneB (talk) 19:26, 20 January 2019 (UTC)
Has anyone ever done scientific experiments on the effects of human isolation over long periods, months or even years?.
BBC - Future - How extreme isolation warps the mind
NASA - Behavioral Issues Associated with isolation and Confinement: Review and Analysis of Astronaut Journals (Journals) - 01.10.19
Alansplodge (talk) 22:45, 20 January 2019 (UTC)

Brown wax[edit]

Why does my ear wax come out brown but then go yellow after rolling it? (talk) 21:49, 20 January 2019 (UTC)

Moisture content and crystal structure. This is typical behaviour for waxes. It's naturally brown and it doesn't go "yellow" (i.e. changes hue), it just becomes a paler brown; it loses transparency as what was previously a homogeneous and translucent material is disrupted.
There's a similar effect if you take coloured candle, cool the wax down (you won't see this effect with warm wax) and bend it - it'll turn white. Andy Dingley (talk) 22:13, 20 January 2019 (UTC)

January 22[edit]

What's the biggest ship that's physically possible to circumnavigate with 1 or 2 people?[edit]

Knock Nevis? You might be avoiding collisions and pirates only by luck though.

What's the biggest that's not much riskier than cargo ships? (which have someone at the bridge, engine and probably lookout 24/7)

Couldn't you put so many computer terminals on a megayacht that nowhere's more then seconds from controls, radar, radio, cameras of EVERYTHING, weather/wave/navigation charts, autopilot etc.? With yellow/red alert lights/120 dB wake up alarms happening when you might need to check a screen cause "there's a radar echo only X miles away", "collision course", "someone might be hailing you", "check engine light", "low oil pressure oi, might want to stop the I'm flying Jack imitation/poop/chess/making out and check for leaks?".. That doesn't seem too dangerous, provided you don't become incapacitated or have to repel pirates. Sagittarian Milky Way (talk) 04:05, 22 January 2019 (UTC)

Just search among the real big Tugboats. The ones that tug Oil platforms on open sea for example. They all use "Voith–Schneider cycloidal propellers" aka Cyclorotor. which allows them to literally turn on the point with ease. These are mostly "manned" with 1 captain and sometimes 1 additional engineer. --Kharon (talk) 04:31, 22 January 2019 (UTC)
When you say "circumnavigate", do you mean circumnavigating the earth? ←Baseball Bugs What's up, Doc? carrots→ 09:37, 22 January 2019 (UTC)
Yes. Sagittarian Milky Way (talk) 13:11, 22 January 2019 (UTC)