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January 14

Liver damage

Request for medical advice
The following discussion has been closed. Please do not modify it.
My mother has liver damage. She claims that the doctor told her to eat food as warm as possible (i.e. hot food, as temperature, not as taste). Is this sound science of quackery? Just to be sure: I am not asking for medical advice, I am asking if it is quackery. Tgeorgescu (talk) 01:43, 14 January 2017 (UTC) Responses deleted. This question is asking for medical advice and we cannot answer it here. --69.159.60.210 (talk) 05:34, 14 January 2017 (UTC) She is addicted to chain letters about miracle cures, that would explain why she has bizarre ideas about medicine. She could believe that such ideas would be objectively true and present them as the advice of her own doctor. Tgeorgescu (talk) 05:36, 14 January 2017 (UTC) You asked editors here, most of whom have no medical training whatsoever, to pass judgement on the advice given by the physician of another individual, and indeed, by extension, on whether that physician is a quack. If you are not happy with your relative's choice of physician, convince her to seek a second opinion. Akld guy (talk) 05:38, 14 January 2017 (UTC) It's an idea which seems bizarre and for which I found zero scientific validation while searching Google and PubMed. So, it was natural to think of quackery. As I stated, it is what she claimed, not what I would know that the physician stated. Tgeorgescu (talk) 05:44, 14 January 2017 (UTC) It's quackery. ←Baseball Bugs What's up, Doc? carrots→ 07:09, 14 January 2017 (UTC) But we don't know in what context the doctor said what he said to the patient with liver damage, who is likely to have some number of physical complaints that may not all be due to the liver problem. Count Iblis (talk) 08:14, 14 January 2017 (UTC) Sorry, but we can't make recommendations regarding the treatment of individual persons. Please seek out a medical professional. Dragons flight (talk) 08:25, 14 January 2017 (UTC)

Stopping power, part 2

OK, I'm now calculating the stopping power of the different cartridges listed using Hatcher's formula (which, BTW, wasn't in the article) and the diameter and momentum values from the table of handgun and rifle cartridges, but I'm getting ridiculously low values -- for example, just over 1 for 9X19 Parabellum hollowpoint, when the BlogSpot article says it should be between 30 and 40. WTF? Is the formula wrong as given in the blog, or are all the momentum values in the table wrong, or am I doing something wrong? 2601:646:8E01:7E0B:F88D:DE34:7772:8E5B (talk) 04:11, 14 January 2017 (UTC)

Actually the 9x19mm Parabellum cartridge's battle record and similar anomalies between the actual performance of various hunting cartridges and the calculated performance according to Hatcher's Relative Stopping Power formula caused firearms writers and US Federal government researchers to take a second look at Hatcher's RSP formula. I would not rely on Hatcher's RSP formula to predict relative stopping power.

I gave you a link to the Blogspot article specifically because the author discusses the work of Martin Fackler and other researchers since Hatcher in estimating relative stopping power. You yourself spotted the same thing Fackler and others did, that highly energetic rounds like 9x19mm Parabellum have an RSP not predicted by the Hatcher formula. Go over that Blogspot article again and our article Stopping Power carefully, and the sources they cite (looking over our article Stopping Power I see several minor defisiencies but it also cites several good sources of information for you in its list of references). Look them up.

This project of yours is not going to be easy, nor should it be. Relative stopping power is even now a contentious issue in the police and military communities - the 5.56x45mm NATO cartridge, long thought when loaded with a boat-tail FMJ bullet to be adequately lethal for military use, has disappointed US ground forces in the Iraq and Afghanistan conflicts, to the extent that the M-14 infantry rifle chambered in 7.62x51mm NATO has been re-issued to Marine and other US forces in the field. Likewise, 10mm Norma, while it tended to destroy service firearms earlier than other commonly used rounds, is enjoying a resurgence of popularity because more durable pistols are now available to fire it, and its increased muzzle velocity gives it a decided advantage in terminal ballistic performance compared to (for example) the .40 Smith & Wesson cartridge (a 10mm cartridge with a shorter case, lower recoil, lower chamber pressure and lower terminal ballistic performance than the 10mm Norma). These are just two instances of ongoing controversy regarding actual relative stopping power versus predicted relative stopping power.

See if you can find tables based on Fackler's work (start by looking up the references cited in our article on Martin Fackler. They may not be absolutely definitive in predicting relative stopping power, but they're bound to be more plausible predictors than Hatcher's RSP formula for modern handgun rounds. I'm not allowed (or inclined) to do this for you, but you seem able to do this yourself. loupgarous (talk) 23:13, 16 January 2017 (UTC)

So are you saying that Hatcher's formula is off by a factor of 30-40? Because I'm getting these ridiculously low values for all of the calibers listed, not just some of them. 2601:646:8E01:7E0B:F88D:DE34:7772:8E5B (talk) 03:32, 17 January 2017 (UTC)

What is string?

Hi, I'm working on the article string (cord).

I'm having a hard time finding sources about string on the Web, and was hoping to avoid a trip to the library. To make the best article possible, I'm interested in everything about string. Including its definition, what classes of things it belongs to, its history (especially its origin), the various types of string, what it is made out of, how it is made or manufactured, uses of string, and so on.

Concerning classes and types, the thread article says that thread is a type of yarn, and some dictionary definitions say that string is made of threads twisted together. So, is string a type of yarn? Or are yarn and thread types of string?

Are string and yarn two different things? If so, what common type of thing are they?

What class of things do thread, yarn, twine, string, cord, and rope belong to?

What are the parent-subtopic relationships here? Which ones are parent topics of what, and which ones should be featured as subheadings of another?

String art, which uses thread, refers to the material used as string.

I'm pretty sure string predates both yarn and thread. See Oldest string found at French Neanderthal site and 30,000 Years Old Wild Flax Fibers - Testimony for FabricatingPrehistoric Linen.

I look forward to anything you can find on the topic of string.

Please provide references.

Thank you. The Transhumanist 10:19, 14 January 2017 (UTC)

This might help = http://wikidiff.com/string/cord Wymspen (talk) 10:51, 14 January 2017 (UTC)

• Cordage might be a useful term, as Big String's blanket term for both strings and ropes.

Conceptually, string goes back to the mesolithic. Fibres, of either plant or more probably animal sinew, were used to attach stone tools to wooden handles. This is supported by grooves in such stones (the string itself is long gone) which, along with better shaping of the stones, can be used to date them from the earlier and simpler hand-held stone tools.

Clothing also involved fibres to connect animal skins for clothing and luggage. We have evidence of this from Europe in the iron age peat bog bodies, or those from glaciers. Egypt is also worth looking at, for a very ancient civilisation with a highly developed textile industry and also good preservation of surviving relics.

In the dark ages(sic) period, much "string" was made by plaiting rather than the twisting we use today. String (today) is made by the twisting together of spun yarns, of long fibres. This needs both the invention of the ropewalk and also a long-fibre yarn with good tensile strength. Weaker yarns are more easily plaited together than twisted. Many fibres were used from the beginning and it was known that the better fibres could be used for stronger tasks, although they were harder to obtain. Wool makes a plentiful fibre that's useful for clothing, but this is too short, thus too weak, for string. It was often knitted, rather than woven, as this involves lower tensions and less demand on the fibre. Breeding of better sheep eventually produced a longer fleece which could be spun to a worsted yarn, strong enough for weaving or even string (worsted string still has a specialist use as oil wicks in the lubricators of steam engines). Plant fibres were bast fibres from beneath tree bark (especially in Eastern Europe) or thinner stem fibres from flax (making linen) or nettles. The Norse peoples in particular developed skilled plaiting and tablet weaving and much of their "string" for luggage or fastening straps was made from flat-woven braids, rather than round cordage. The Celts, particularly in Ireland, made great use of horses and needed strong cordage for harness and chariot fittings. Horses supplied this too, as either leather strips or as horsehair, the longest and strongest fibre available in the period, which was spun and used for cordage rather than weaving. Andy Dingley (talk) 11:34, 14 January 2017 (UTC)

You've provided some good ideas on what to look for. Thank you. The Transhumanist 09:03, 15 January 2017 (UTC)

(edit conflict):The word itself goes back thousands of years and was originally used for any thickness, but the OED says: "In modern use: a thin cord or stout thread.". For etymology, the OED has: "Old English stręng (masculine) = Middle Low German strenk, strenge, Middle Dutch strenghe, stringhe (modern Dutch streng, feminine), Old Norse streng-r (masculine) (Danish streng, Swedish sträng) < Germanic type *straŋgi-z; another declensional form is found in Middle Low German strank, strange (masculine), Old High German stranc (masculine) (Middle High German stranc, strange (masculine), feminine, modern German strang, masculine) < Germanic type *straŋgo-z, < *straŋg- < pre-Germanic *stroŋk-: *streŋk-. The pre-Germanic root *streŋk- appears not to be known in this form, but a parallel form *streŋg- is represented by Irish (and Scottish Gaelic) sreang cord, string, Middle Irish srincne navel-string, Greek στραγγάλη halter, Latin stringĕre to bind, draw tight. Connection with strong adj. is doubtful." (but you've probably seen this).
Just in case you don't have access to the OED, yarn is also a very old word. The OED has the etymology: "Old English gearn strong n. = West Frisian jern , North Frisian jaarn , juarn , Middle Dutch gaern , gar(e)n (Dutch garen ), Old High German, Middle High German, German garn yarn, †net, Old Norse (Swedish, Danish) garn (whence garn n.); apparently < the root represented also by *garnô in Old Norse gǫrn , plural garnar guts, and *garnjo- in Old English micgern , Old Saxon midgarni , Old High German mittigarni midgen n. (= entrail-fat, suet), and related (outside Germanic) to Lithuanian žárna intestine, Latin hariolus soothsayer, haruspex one who divined the future from an inspection of the entrails of victims, Greek χορδή intestine (chord n.1). (Compare, moreover, Sanskrit hirā vein, Latin hīra empty gut, hillae < *hirl- smaller intestines.)" and says: "Originally, spun fibre, as of cotton, silk, wool, flax; now, usually, fibre spun and prepared for use in weaving, knitting, the manufacture of sewing-thread, etc." and "In Rope-making, one of the threads of which a strand of rope is composed".
Thread is also very old with the OED definition: " A fine cord composed of the fibres or filaments of flax, cotton, wool, silk, etc. spun to a considerable length; spec. such a cord composed of two or more yarns, esp. of flax, twisted together; applied also to a similar product from glass, asbestos, a ductile metal, etc." and etymology: "Old English þrǽd = Old Low German *þrâd (Middle Dutch draet , Dutch draad ), Old High German, Middle High German drât (German draht ), Old Norse þráðr (Danish traad , Swedish tråd ) < Old Germanic *þræ̂-ðuz , pre-Germanic *trētús ; < *þræ̂- to twist". Sorry I can't find any useful references other than the dictionary. Dbfirs 11:44, 14 January 2017 (UTC)

This will definitely help build an etymology section for the article. Thanks. The Transhumanist 09:03, 15 January 2017 (UTC)

You many also want to include as section on how long a piece of string is. Hayttom (talk) 18:31, 14 January 2017 (UTC)

Usually about an inch shorter than you need it to be. Wymspen (talk) 21:53, 14 January 2017 (UTC)

"String is a / Very important thing / Rope is thicker / But string is quicker". (Spike Milligan) [1] Alansplodge (talk) 19:46, 14 January 2017 (UTC)

String is clearly almost certainly possibly made out of string (physics), nyuk nyuk. (Wish I had something more insightful to say...) Wnt (talk) 22:51, 14 January 2017 (UTC)

Is yarn a type of string?

Or is it the other way around? The Transhumanist 20:36, 15 January 2017 (UTC)

Is string a type of cord?

The article was renamed to string (cord), so we need to know the relationship between string and cord.

Is string a type of cord?

Or...

Can cord be made from string?

Or are string and cord siblings?

Is string a type of cordage, along with cord and rope?

The fate of the title hangs in the balance. :) The Transhumanist 22:51, 15 January 2017 (UTC)

What is cordage?

Cordage obviously includes cord and rope. But does it also include string?

(Need references). The Transhumanist 20:36, 15 January 2017 (UTC)

Cordage is usually taken to be the most general term for strings and ropes etc. Wire rope is cordage, twine and yarn are cordage. If it's made with a fiber or a wire, and much longer in one dimension than any other, we can call it cordage. See. e.g here [2] SemanticMantis (talk) 15:57, 16 January 2017 (UTC)

EU power cable mod

I ordered an induction stove from Germany to my country - Vietnam. In order to make it work, I had to mod the power connector from 3 pin to 2 pin (with 1 pin discarded) because the power socket in my country contains only 2 (see image here). Then we continued to order another one (namely Siemens HMI40PC). But this time, I am confused because it comes with a 4 pin power connector (see image here). Could somebody show me how to get it work? By the way, there is a small 2 pin connector of unknown purpose (see image here). I lost the English version of the manual, and it is hard for me to guess what that thing does. Livy (talk) 12:27, 14 January 2017 (UTC)

Maybe you could google the manual. I found this and this. I'm not sure it is what you want. Good luck. Anna Frodesiak (talk) 12:44, 14 January 2017 (UTC)

Okay, I was way off with those links, but think I am finding the right ones now. I am looking but someone may beat me to it and give a link first. Anna Frodesiak (talk) 12:46, 14 January 2017 (UTC)

How is this? Am I getting closer? Anna Frodesiak (talk) 12:49, 14 January 2017 (UTC)

Cutting off pins on a power cord is a great way to kill yourself from electrocution. The pin is probably a ground connector, so that if there's an electrical fault in the device the current shorts out and trips a fuse/breaker instead of going through you when you touch it. If you are not an electrician, do not attempt to modify electrical devices to "make them work". Consult a licensed electrician. (Maybe it's time we expand the Ref Desk prohibition on medical diagnoses and legal advice to include other "licensed" professions like electrician and plumber.) --47.138.163.230 (talk) 13:36, 14 January 2017 (UTC)

Agree. The three connectors are phase, neutral, and (protective) earth. The last one keeps all parts of the system that are not supposed to carry electricity at ground potential, so there is no difference of potential between the ground and the device. This protects you from becoming the grounding connector (i.e. electrocuting yourself). The four-connector stove is designed for the German market, where in addition to the normal 230V two-phase power supply, all dwellings are also supplied with 400V three-phase electric power that is in particular used to connect electrical stoves. The 4 connectors are two of the phases, neutral, and earth. It is possible that the device can be connected to 2-phase 230V systems (in particular if it's design also covers the rest of the EU), but you really need to get an expert to determine that and make it work. You won't be able to use full power of the stove with a two-phase connection. And you should certainly make sure that your devices are grounded properly. --Stephan Schulz (talk) 14:11, 14 January 2017 (UTC)

@Stephan Schulz: I was pretty sure that three-phase power had ... three phases. And that's what the article says. It also says there's one "neutral wire" in some of these distributions, which can form a single phase power supply with any of the three, so I take it that's about the equivalent of the white non-live but non-ground wire in an American two-prong outlet (give or take voltage). I certainly can't rule out you're right though from first principles ... if homes can receive one of the three phases only I suppose they could receive two plus neutral and ground. Wnt (talk) 22:59, 14 January 2017 (UTC)

Perhaps S.S. had imbibe too much schnapps when he posted that and was phased by all the phases ;¬) --Aspro (talk) 23:43, 14 January 2017 (UTC)

Hicks. But seriously, in Germany the normal 3-phase connector has 5 wires - L1, L2, L3 (the three phases), N (neutral) and PE (Protective Earth). For reasons best known to electricians, for a stove you use two of the phases (normally L1 and L3) and N to draw power. You use PE to not get killed. If you also connect an oven to the same socket, you use L2 and N (and PE). --Stephan Schulz (talk) 01:22, 15 January 2017 (UTC)

(ec) Yes, there is a safety issue when you discard the power wire because it almost certainly serves to ground the exposed metal parts of the stove. One appreciates that in Vietnam two-pin mains sockets that roughly conform to Type C "Europlug" are widespread but according to our information sockets like this that has a 3rd ground connection are available. I strongly advise you to have one installed by an electrician competent to make the Ground connection secure, for the future safety of all users of the oven.

The Siemens HMI40PC may require a 3-phase mains supply that you would need specially installed. The supplier, not Wikipedia, should answer this question which you can send to [email protected]. Once again, consult a competent electrician. (S)he will also be able to confirm the purpose of the small 2-pin connector which is likely to supply power to a separate device such as a lamp or extractor fan. Blooteuth (talk) 14:14, 14 January 2017 (UTC)

• I don't believe that is a simple power plug. I think it is designed to plug into a special power supply or power converter device, not into any sort of wall socket. You really need to ask the manufacturer about this. Looie496 (talk) 17:49, 14 January 2017 (UTC)

• @Livy: Forget most of the advise above. The first power cord with 3 wires is the one you need. Remember that blue is neutral, brown is phase and the yellow/green is ground. If you don't connect the ground you'll be not safe if there is a short so you should find a way to connect it somehow. Find someone who knows what they're doing for that part. The 4-prong wire is to connect to an optional oven (see the label in your picture). So if you don't have an oven you won't need it. And it's NOT a 3-phase connection as was mentioned above. Why I know all this? Because I looked at the manual in the link you've provided. Cheers. 195.78.229.37 (talk) 01:33, 15 January 2017 (UTC)

The first image belongs to the old stovetop. And while I could be mistaken, the label in the second image tells you where to connect PE to the stovetop and optional oven. The yellow (and green, though it's hard to see) cable is PE (and if so should be connected to earth). The other 4 connected to the 4-pin plug (which I have never seen before) are most likely the 3 phases (grey, brown, black) and neutral (blue, connected to the slightly longer pin of the plug). At least that would be the correct colour coding, which I would expect from Siemens. And that would mean that this is indeed a 3-phase connector. --Stephan Schulz (talk) 08:17, 15 January 2017 (UTC)

Damn you, Schulz, you're right. Here is an image for the connections. They'll need to combine wires as shown in the third option labeled 220-240V 1N.--TMCk (talk) 14:37, 15 January 2017 (UTC)

Nay good Sir, if there be cause for damnation I beg you spare the innocent Stephan Schulz and do plead Mea culpa to the Original sin of triphasic correctitude. Blooteuth (talk) 15:11, 15 January 2017 (UTC)

I'd note that the specs seem to suggest the hob uses 7200W. I don't know whether this is different if you connect it in the one phase fashion, but there's still a fair chance it'll use more than whatever power sockets and possibly the cables connecting to them are able to support. In other words, emphasising what others have said above, you really need to get a qualified electrician to do the installation. Nil Einne (talk) 16:03, 15 January 2017 (UTC)

Agree that the OP must have this hob installed by a qualified sparky. Say the hob does indeed draw 7200 on full load. That is some 33 amps at 220 volts on single phase. In Germany and other mainland countries that instal 3 phase to modern homes, they like to keep each phase current to no more than 16 amps (hence the preference for 3 phase hobs). So a cable that can carry that amperage (33 amps), on single phase, needs to be a 'new' cable run from the distribution board. Also the sparky may discover that the board is already linked up to an earth spike to anchor the neutral line to earth as it enters the property. So the job of providing the PE (protective earth) to the hob becomes a very simple and inexpensive matter. Modern safety devices no longer need an earth to cut-out when there is an imbalance between lines but the reason that there are so few deaths to day is because of the belt and braces approach which include every good practice being adopted. On the up side however: You (or one of your family members) can only suffer death through electrocution once in a lifetime.--Aspro (talk) 16:05, 16 January 2017 (UTC)

Aside: Regarding the power plug in the image. My thoughts are: As these hob roll off the production line they need to be quality checked. It saves time (and avoids operator errors) if all conductors are not free but bonded together so the cable can just be plugged into the tester by the operator. Can not tell by the image provided but I guess that that the pin pitch corresponds also the the terminal block pitch in the kitchen junction box. After all, this is most likely the only 3 phase appliance one owns and one doesn't move them around from room to room. So there is little point in having a more expensive 3 phase plug and socket. So they are just permanently hard wired in to the electrics via a junction box. Once screwed into the terminal block, the electrician can add the links and so forth on the other side and thus avoid invalidating warranty. It is also simpler as he only has to remember the power side and is thus less likely to make a mistake. What we really need is an input from a sparky that does this for a living and is still alive to tell the tale. --Aspro (talk) 17:08, 16 January 2017 (UTC)

Why are the leaves still red? The sequel

Referring to this question, I thought I saw the plant yesterday but it was a different one. Although the red leaves are starting to curl up, everything is still red.— Vchimpanzee • talk • contributions • 16:10, 14 January 2017 (UTC)

Chlorophyll is a metabollically expensive pigment; it is sequestered by the plant while the leaves are alive, so it is not degraded by winter conditions, but is absorbed. Any pigments left in a dead leaf once it is dead (and has lost its vascular connection to the stem) is simply dead. It will decay according to ambient conditions, but not according to any purposeful action of the plant or set schedule. μηδείς (talk) 22:10, 14 January 2017 (UTC)

Are there units that take spacetime into account?

Like kilogram-seconds (mass times how long it's existed (now or all time including the future)), liter-seconds, meter-seconds, mile-years (Appian Way > Trans-Siberian Railroad) Sagittarian Milky Way (talk) 20:54, 14 January 2017 (UTC)

Might be difficult, since space-time is warped around massive objects, and subject to change as those masses change. So defining the space-time of a region would be a bit like defining the surface area of a balloon that's continuously expanding and contracting. StuRat (talk) 21:52, 14 January 2017 (UTC)

Mass-energy isn't really known for being created or destroyed, just moved around, so I don't get your definition. But Planck units might provide some ideas for making weird, creative conversions. (See nondimensionalization, though to this non-physicist this seems like it should be a tooth-clenching exercise in stripping meaning and dimensional analysis from any situation) Wnt (talk) 23:01, 14 January 2017 (UTC)

I mean a (probably useless) unit where an uncut diamond can be more time-massive (timassive?) than a billion tonne iceberg that has just broken off. The iceberg has to exist for about 1.6 minutes to accumulate enough gram-years to beat a 1 gram 3 billion year old diamond. Likewise in relative terms the Egyptian economy still clobbers the EU's in spacetime (The EU has had a quarter the world GDP for 23.1 years. Egypt only needs to average 1/800th the world GDP for the last 5,000 years to have more gross world product fraction-years. It has 1/200th world GDP even now) Sagittarian Milky Way (talk) 01:30, 15 January 2017 (UTC)

I don't think you're talking about space-time; you're just talking about time. You want to multiply some quantity by the length of time it exists. That has nothing (or not much) to do with the concept of spacetime. CodeTalker (talk) 01:59, 15 January 2017 (UTC)

Very well. See four-dimensionalism though. Sagittarian Milky Way (talk) 02:36, 15 January 2017 (UTC)

See Spacetime interval--213.205.192.126 (talk) 01:26, 15 January 2017 (UTC)

If this were the humanities desk I might direct you to Perdurantism and worm theory, but, from a Science viewpoint, you might also be interested in World line. Dbfirs 12:00, 15 January 2017 (UTC)

Accumulated loan Interest of the Simple kind in economics is $rBm$ where

r is the simple annual interest rate

B is the initial balance

m is the number of years elapsed. Blooteuth (talk) 14:51, 15 January 2017 (UTC)

Along those lines, future value may also be thought of as a quantification from economics that includes a time component. SemanticMantis (talk) 15:53, 16 January 2017 (UTC)

Nasal breathing and tonsils

I saw the next question on facebook group "Hypertrophy of one of the following can be a reson for difficulty nasal breathing. A. Tonsilla pharyngea B. Tonsilla palatina C. Tonsilla lingualis D. Tonsilla tubaria E. All above mentioned tonsils". The answer there is option a. no explanation and I suspect that's not the answer since it doesn't make sense to me according to the link to an article which I saw here on the article "tonsil" ("Obese children with SDB had larger palatine tonsils than did normal-weight children with SDB. This finding suggests that larger palatine tonsils may have a greater effect on upper airway obstruction in obese than in normal-weight children with SDB.). Then I suspect the answer is not Tonsilla pharyngea as it's written there. Is it right? 93.126.88.30 (talk) 21:50, 14 January 2017 (UTC)

I added a title. StuRat (talk) 21:52, 14 January 2017 (UTC)

I saw almost the same question also here (no.83) with same answer. 93.126.88.30 (talk) 02:57, 15 January 2017 (UTC)

January 15

Physical interest/meaning of a certain Bernstein function

A quick question: consider the Bernstein function f(x):=-ln(1-exp(-x)), for x>0. Is this function any interest, or has it any meaning in Mathematical Physics, or more generally in some area of Physics? --151.29.234.2 (talk) 11:17, 15 January 2017 (UTC)

As a Mathworld link notes, completely monotonic functions occur in elasticity where Hooke's law F = kX applies to the special case of small deformations that exhibit Linear elasticity, and in larger deformations that are non-linear functions of applied strain, but not after non-reversible yield occurs. Blooteuth (talk) 14:37, 15 January 2017 (UTC)

Feynman Lectures. Lecture 44. Ch.44-4 The efficiency of an ideal engine [3]

...

Now we shall see how this universal law could also be obtained by logical argument, without knowing the properties of any specific substances, as follows. Suppose that we have three engines and three temperatures, let us say T1, T2, and T3. Let one engine absorb heat Q1 from the temperature T1 and do a certain amount of work W13, and let it deliver heat Q3 to the temperature T3 (Fig. 44–8). Let another engine run backwards between T2 and T3. Suppose that we let the second engine be of such a size that it will absorb the same heat Q3, and deliver the heat Q2. We will have to put a certain amount of work, W32, into it—negative because the engine is running backwards. When the first machine goes through a cycle, it absorbs heat Q1 and delivers Q3 at the temperature T3; then the second machine takes the same heat Q3 out of the reservoir at the temperature T3 and delivers it into the reservoir at temperature T2. Therefore the net result of the two machines in tandem is to take the heat Q1 from T1, and deliver Q2 at T2. The two machines are thus equivalent to a third one, which absorbs Q1 at T1, does work W12, and delivers heat Q2 at T2, because W12#W13-W32, as one can immediately show from the first law, as follows:
W13−W32#(Q1−Q3)−(Q2−Q3)#Q1−Q2#W12.(44.8)
We can now obtain the laws which relate the efficiencies of the engines, because there clearly must be some kind of relationship between the efficiencies of engines running between the temperatures T1 and T3, and between T2 and T3, and between T1 and T2.

— Feynman • Leighton • Sands, The Feynman Lectures on Physics, Volume I

First, I don't understand why W₃₂ is negative and why is calculated as Q₂−Q₃ and not Q₃−Q₂.
Mathematics must be correct in all cases, even if we don't know is the work done on or by the machine 2.

Second. How to calculate efficiencies? I try next:
$\eta _{\text{machine 1}}={\tfrac {W_{13}}{Q_{1}}}$

$\eta _{\text{machine 2}}={\tfrac {W_{32}}{Q_{2}}}$

$\eta _{\text{machine 3}}={\tfrac {W_{12}}{Q_{1}}}$
$W_{12}=Q_{1}-Q_{2}$
$W_{13}=Q_{1}-Q_{3}$
$W_{32}=Q_{2}-Q_{3}$
$(W_{13}-W_{32}=W_{12})$
So we have 6 equations and 9 unknowns. The system is unsolvable. Username160611000000 (talk) 12:55, 15 January 2017 (UTC)

• we have 6 equations and 9 unknowns. The system is unsolvable. - I will just "answer" that part, because I think you can genuinely profit from it.

The ideal gas law states that $P=\rho R_{\text{specific}}T$. That is a "system" of one equation and three unknowns (pressure, density and temperature), hence unsolvable. So what? Tigraan^{Click here to contact me} 18:32, 16 January 2017 (UTC)

Tritium tube concentration and pressure for brightness

When tritium is put into one of those glowing glass tubes is it put in at 100% concentration or could it be concentrated to make them brighter? If the tube was made from a thicker or different material could it be put in at higher pressure in order to make the tube brighter? --78.148.97.148 (talk) 14:27, 15 January 2017 (UTC)

It's 100% concentration of hydrogen at a couple of atmospheres pressure. It's generally easier to make and fill vials at above atmospheric pressure than below. The brightness is controlled by the phosphor coating, the lifetime of the tube by the tritium fill. It's easy to make a new vial maximally drive the phosphor, but this gets harder as the tritium decays. Tritium's half life is 12 and a third years, Betalights are usually specified for a fifteen year lifetime and are usefully visible for maybe two halflives (thus a quarter of the original activity, possibly with degradation of the phosphor too). The brightness of the tube depends on the surface area, the activation power and the lifetime from the tube's volume. So the ratio between volume and area (i.e. tube radius or disc thickness) is important - a narrow tube may need a "powerful" fill. The "tritium" fill is never pure tritium as that's hard to arrange and of no real use - some will just be protium (vanilla hydrogen). If a tube is quite large but doesn't need to be especially powerful, then the gas pressure is usually kept the same, but there's a mixture with less tritium in it.

The radioactivity of the complete vial is usually limited by paperwork: most are kept to 1GBq, larger ones up to 10GBq are also used. Over 10GBq does need paperwork per device - so they're used, but discouraged, especially for civilian purposes. Andy Dingley (talk) 15:48, 15 January 2017 (UTC)

Agree with AD. The phosphor coating can only release a fixed amount of photon energy after being excited. So when the tritium concentration is higher enough to re-excite the phosphor atoms the moment they return to their rest state, no extra luminance is going to be forth coming. Therefore, the only option is to increase the surface area. Best way to do that is to use lots of very thin tubes as the ratio of surface area is greater for any given volume. Of course, if it were possible to get the pressure high enough and the gas hot enough it would get suddenly very bright indeed – at the same time as lowering the local real-estate values around where you live (or that should be in the past tense -lived). Aspro (talk) 18:52, 15 January 2017 (UTC)

The article Tritium illumination describes the construction of "beta lights" that consist of a glass tube with its inner surface coated with a phosphor and filled with Tritium a radioactive isotope of hydrogen. Having with a half-life of 12.32 years, tritium lights lose half their brightness in that period. The more tritium that is initially placed in the tube, the brighter it is to begin with, and the longer its useful life. Installing tritium at higher than atmospheric pressure can increase brightness and useful lifetime but at higher cost, require a thicker tube for strength, and possibly raise safety concerns since escaped tritium is a radioactive hazard. Blooteuth (talk) 19:50, 15 January 2017 (UTC)

"tritium lights lose half their brightness in that period."

But they don't. Nor are "lots of very thin tubes" a good or economical idea.

Tritium lighting is mostly used for self illumination. But a decade or two ago, before useful LED torches, when tritium was still sometimes used to make torches usable for map-reading, these were discs rather than tubes. The diameter of the disc controlled the brightness, the thickness controlled the life. Andy Dingley (talk) 23:45, 15 January 2017 (UTC)

Our article tritium illumination says that there are "several thousand" times more tritium in a nuclear weapon than in a keychain. I assume this is a slight underestimate... :) Some folks above sound like they are familiar with the topic - can someone put an actual sourced number for that difference in the article? Wnt (talk) 17:54, 16 January 2017 (UTC)

• Article should be renamed as Tritium luminance. As anybody whom did the 101 knows 'illuminance' is the light falling upon an object etcetera., not the light emitted by the source (which is the luminance). Heard it said, that the amount of hydrogen needed to boost a nuclear device is no more than that which would fill a child's party balloon ( at standard temperature and pressure) which if one considers, that volume is well over a thousand time more than a keyring light. The Hydrogen then gets confined in a 'small' titanium bulb within the core. Extra tritium can be provided by the transmutation of lithium, once fusion has started. Would love to build one but don't know of anyone with a big enough back-yard to test it in. Mind you... Kim Jong-un appears to have a similar amateurish interest and has a very large range of unpopulated land. Does anybody have his email address? Lastly. A disc is very inefficient as approx half the energy is lost on the obverse face.--Aspro (talk) 21:34, 16 January 2017 (UTC)

Tritium radioluminescence might be justified as a redirect, but as many tritium illuminators are used for illumination of signage as are used for luminescence. They were originally developed as dial illuminators and the name stuck. Also we're under COMMONNAME, not just waving around personal erudition.

As to nuclear weapons, tritium and lithium, then you're confusing the two (boosting vs. secondaries).

If discs aren't used for Betalights, then you might like to inform Betalight themselves [4]. When used one sided, they're usually painted white on the back face. Andy Dingley (talk) 21:54, 16 January 2017 (UTC)

Where did I say they were not used. Talked about efficiency. Tritium radioluminescence seem very acceptable though. As for COMMONNAME, there are some nomenclatures that as an encyclopedia we should get right.  ! Otherwise 'we' would be contributing to positive feed-back (think audio howl). Said that "Extra tritium can be provided by the transmutation of lithium" so of course it is secondary so don't see why you think I'm confused by any of what I said.--Aspro (talk) 23:34, 16 January 2017 (UTC)

I looked up hydrogen bomb and was amazed to read that the fusion fuel is actually lithium deuteride, not tritium at all! It didn't give a quantity - a non-reliable source [5] estimates up to 10,000 kg in the largest fusion bomb but I doubt they had their math right. I don't think it's a party balloon but honestly I should admit I don't know. It seems like every time I look up nukes they seem to operate a completely different way... I get the feeling that there's been a lot of misinformation spread around. Wnt (talk) 21:58, 16 January 2017 (UTC)

Having said that. Beta touches are almost exclusively used by the US military and as the US tax payer picks up the bill there is really no need to consider efficiency nor cost. If Walmart started selling them however, the design and construction may very well change. --Aspro (talk) 21:48, 16 January 2017 (UTC)

They're hardly used by the US military. The UK have always been bigger users. Also I can't speak for Walmart, but plenty of outdoor dealers carry small ones, and used to carry the larger torches (obsoleted by LEDs). [6] Saunders-Roe sell them mail-order too - the shipping boxes are great for terrifying the postman. Andy Dingley (talk) 21:56, 16 January 2017 (UTC)

That link appears to go to a Swiss company (you know, those folks that invented the cuckoo clock) and they don't seem to declare their NATO reg. May say MOD Patt. But that can just be sales and marketing puffery. Other companies proudly show their NATO. As far as I'm aware the British Army still relies on a good old box of Swan Vesta. Failing that, they just rub two boy scouts together [7] ;¬) .--Aspro (talk) 22:55, 16 January 2017 (UTC)

NSN 6260-99-965-3582 Andy Dingley (talk) 23:26, 16 January 2017 (UTC)

Andy Dingley is right (dam him). This company does supply products to NATO standards. However, I'm still going to stick with my Swan Vesta's (Vesta was the goddess of something or other and one can't go wrong with a woman behind you.) --Aspro (talk) 00:52, 18 January 2017 (UTC)

Vesta (mythology) was "the virgin goddess of the hearth" amongst other things. See also Vesta case and indeed Swan Vesta. You might have thought that England's Glory might be more appropriate (and safer if you work with explosives). Alansplodge (talk) 18:16, 18 January 2017 (UTC)

Helicopters and drones on Everest

There are apparently a lot of touching movies about lunatics who follow the siren song of Everest and K2, and the hardships they suffer because everything has to be carried up with great effort and no medical rescue is possible. Looking around on the Web, it seems like this is still the case, even in 2016. For example, I see that helicopters can barely make the second base camp at 20,000 feet (i.e. 50% shy of the summit) and supplies are still being carried over a dangerous ice fall by teams of Sherpas, though at this lower altitude helicopters might compete.^[8] Now, I can't knock them for making a living, especially if that's what they have to do to do so, but still, well, if Everest is a mountain of dreams, then it makes me dream that if I were a big shot at a company like Starbuck's I'd want to arrange drones to fly over and drop off and ideally assemble all the components and supplies for a large made-to-order hot cappuccino machine at the summit. Or at least try to hit the occasional downed climber with a falling oxygen bottle. And the funny thing is, I look them up and I see that drones are flying over, mapping glaciers,^[9] making lovely photos.^[10] At lower altitudes in the Himalayas they drop supplies now.^[11] So I gotta ask:

a) Why haven't drone supply operations more or less totally taken over all the big Himalaya climbing routes?

b) Is it possible to make a helicopter that reliably carries a full load to the summit of Everest? With modern technology, could you put in computer stabilization so that even an inexperienced pilot can tell it to resist the wind and keep it flat and level under adverse weather conditions? For that matter, if you were willing to blow enough money on construction and fuel consumption (and what do Himalayan climbers do but blow money) could you make a helicopter that can fly against the wind in a class 5 hurricane, hover right amid the flames of a burning World Trade Center tower, and safely board people on and off over a gangplank in the process losing no more than a bit of scorched hair? Or is there some theoretical limit as to what can possibly be stabilized against, no matter how good the electronics? Wnt (talk) 20:03, 15 January 2017 (UTC)

Well if a vulture can fly at 37,000 feet I'm sure it must be possible to build a helicopter to get to 29,000 feet - just it hasn't been in anybody's interest to do so. It is easier to get things that fly rapidly to fly higher - but vultures don't tend to go very fast. Making a drone that goes that high might be a bit easier than convincing anyone to make a helicopter. Dmcq (talk) 23:55, 15 January 2017 (UTC)

Not only is it possible, it's already been designed and built, and almost 40 years ago, too: Aérospatiale_SA_315B_Lama 89.120.104.138 (talk) 13:37, 16 January 2017 (UTC)

Nope, about 12,000 feet short. 2601:646:8E01:7E0B:F88D:DE34:7772:8E5B (talk) 09:42, 17 January 2017 (UTC)

"on 21 June 1972, the type established a helicopter absolute altitude record of 12,442 m (40,814 ft)", type certificate limits for safe commercial operation notwithstanding. 89.120.104.138 (talk) 09:08, 18 January 2017 (UTC)

I bet they stripped it down to the airframe (and the bare minimum of fuel needed for safe flight) for the record attempt, and used thermals just like Didier Delsalle -- and besides, they probably used translational lift the whole way (i.e. no hovering)! 2601:646:8E01:7E0B:F88D:DE34:7772:8E5B (talk) 09:23, 18 January 2017 (UTC)

Yes, see here: https://www.thisdayinaviation.com/21-june-1972/ . Also, the Everest summit is some three miles down from record altitude. MHO, you need evacuatin' from the Everest summit, a SA315 or similar (enclosed cockpit, space frame fuselage, lightweight construction, stripped down to the essentials) is the tool for the job. 89.120.104.138 (talk) 10:32, 18 January 2017 (UTC)

Odd, I'd think it would be worth it to the Chinese just to hear some Nepalis say "thank you for maintaining an airbase in the Tibet Autonomous Region"... Wnt (talk) 00:25, 16 January 2017 (UTC)

Didier Delsalle. --Hillbillyholiday ^talk 00:29, 16 January 2017 (UTC)

Well, a drone with just a mini-camera is one thing, but a full-size chopper for carrying supplies is another thing entirely -- a bigger payload requires more lift, which requires a bigger machine, which means still more lift -- and that means that the gross weight increases faster than the payload, until you reach a practical limit. And in the case of Everest, the high altitude compounds the problem -- thinner air means (1) less engine power, and (2) less rotor efficiency (these things compounding each other once again, meaning that the service ceiling decreases disproportionately as the gross weight increases). Now, you could try to overcome this in 4 ways -- you can try making the rotor bigger, but then you make it heavier, and above a certain size you'll run into problems with resonance; you can add more blades, but this also adds weight, and when you have more than 7 blades you start getting diminishing returns from each additional blade; you can use 2 rotors, but that also adds weight (not just the rotors, but the additional transmission shafts and gearboxes, and also additional structure for carrying the rotors) and mechanical complication; or you could spin the rotor(s) faster, but above a certain rotor RPM you'll run into advancing blade stall (which also occurs sooner at 29,000 feet than at sea level, because of the lower speed of sound). So, carrying a payload to the top of Mount Everest is in fact a very hard engineering problem -- not that it won't be solved someday, just not any time soon. 2601:646:8E01:7E0B:115A:F5FE:40F5:A40A (talk) 02:34, 16 January 2017 (UTC)

Another problem with manned helicopters is that to fly to that height they need to be pressurized, and this means the crew can't just jump out when they land and load in a patient to be evacuated, they would need people on the ground to load the patient into a sealed nacelle pod, and that pod would need to slowly increase the pressure from the starting pressure to that of the landing level pressure, so it can be opened when they arrive. Even an evacuation drone would still need that second part. StuRat (talk) 07:35, 16 January 2017 (UTC)

• A helicopter has landed on the peak of Everest - see Didier Delsalle. This needed the helicopter to be stripped back to the bare minimum (no extra seats, for instance) and very careful thermal riding to get to the summit. A helicopter has never been usefully to the summit, but Sudarshan Gautam was rescued pretty close to it at 7,800 m (25,590 ft) (see Eurocopter AS350 Écureuil#Operational history). So it is possible - so why isn't it common? This article is a pretty good summary: The problem is that it's only barely safe at the best of times - in good weather, the engine can just grab enough oxygen to keep you airborne, but good weather isn't exactly common on Everest, and Nepal doesn't exactly have a good track record for air safety - without good regulation, when there are multiple companies all competing to be the cheapest and highest-flying, safety goes out of the window. Smurrayinchester 08:23, 16 January 2017 (UTC)

The Delsalle case is interesting - it says that the weight was trimmed to increase the one-hour fuel range of the helicopter. So there actually is some kind of a physical limit here, though it also involves the breadth of the mountain and not just its height. But I don't know whether that limit can be evaded by making a much larger or a much smaller helicopter with proportionally much more fuel storage; I suppose in concept a more energy rich fuel might be used, or an in-flight automated refueling system, etc. The prospect of trying to steal a great pilot's skill and implement it standard in the helicopter computers, including some more effective imaging of winds, also seems interesting. Wnt (talk) 12:24, 16 January 2017 (UTC)

Re a): Something not so far addressed – doing it as much as possible (including the preliminaries) without machine assistance is kind of the point of the whole exercise. I mean, I've crossed the English Channel/La Manche a number of times by ferry (and gone under it several via the Chunnel), but some people still want to do it the hard way. {The poster formerly known as 81.81.230.195} 2.122.62.241 (talk) 12:15, 16 January 2017 (UTC)

The problem with that idea is that I'd expect those following it not to use fixed ropes on the ascent, for example, but to not care whether the supplies they find at Base Camp N were taken up by Sherpas two weeks before or by a bunch of little drones. Wnt (talk) 12:24, 16 January 2017 (UTC)

Probably not. But why would they want to use drones? In the short term, it's not likely to be cheaper, considering pretty much no one is doing anything remotely like that (see Delivery drones, there are a few minor trials but mostly it's just talk). And while there are perhaps some minor advantages in doing it somewhere like Everest (a lot less crowded than some other proposals and possibly the world media is less likely to care if you injure or kill a Sherpa then if you do so to some rural Japanese person), there are as mentioned above and should be obvious a lot more challenges. And you'd piss the hell out of the Sherpas who you still need as guides, to set up the ropes etc. Heck it seems doubtful that either they or the Nepalese government would allow it. (Well for the later, perhaps if you bribe the right people but you aren't exactly helping the business case with that.) It's not like there aren't already serious disputes [12] [13] [14] and ironically IIRC one of the people attacked was actually a helicopter pilot sometimes or often involved in rescue flights. All in all, this seems a lose lose proposition for everyone involved. To put if a different way, if Starbucks really think a coffee machine (which they'd also have to design, probably with pressurisation etc) on Everest is a good marketing stunt, they could just hire a bunch of Sherpas and find someone involved in the company to accompany it. At least then it's only going to backfire because people comment on more junk on Everest rather also because of the drone stuff. Nil Einne (talk) 16:13, 16 January 2017 (UTC)

• Helicopters (drone or not) must hover, and this is hard at high altitude. You need to hover to retrieve people or stuff, but not to deliver it. You can deliver using controllable parachutes from a fixed-wing aircraft. Of course, if this were done routinely, the mountain would soon be festooned with parachutes. You could probably work out a system that delivers heavy loads by a parachute that has some sort of balloon/drone combination to bring unloaded system back down to base. -Arch dude (talk) 04:32, 17 January 2017 (UTC)

Personally I wonder why a person would want to use a drone. What is the point of climbing Everest if it is not a challenge and there is no danger? One might as well have a pressurized funicular railway and a cafe selling cappucinos and Mount Everest souvenirs at the top. Dmcq (talk) 09:47, 17 January 2017 (UTC)

But before anyone invests in a tourist railway to Hotel Miyolangsangma, note that a funicular would need a system of Airlock doors to protect occupants against the 3x air pressure difference between sea level and the summit 8848 m higher. Any idea of stepping outside is not for general unequipped public. Only cold coffee is available outdoors. Blooteuth (talk) 15:30, 17 January 2017 (UTC)

Note that the lower air pressure could be somewhat countered by increasing the oxygen percentage, which would certainly be simpler to do (people just wearing oxygen tanks would do it). However, some people suffer other problems from the lower pressure alone, and these are sometimes fatal. So, maybe you could go halfway up with just oxygen supplements, but then it would be a good idea to pressurize the cabin if going higher. With a 2-stage system, people could get out of the oxygen supplemented funicular, and step into the pressurized one, perhaps after they take a rest stop, eat a meal, etc., on the way up, then do the reverse on the way down. StuRat (talk) 16:40, 17 January 2017 (UTC)

Well, ideally, people run a highway from Kathmandu to Lhasa that tunnels deep below grade, at least enough not to exceed the elevation of the latter city, and then visitors just ride an elevator up from it to a pressurized crystal sanctuary in the sky high above the summit. If they want they can depressurize, or preferably, wear some more comfortable technically advanced pressure suits, and walk along the gangplank from where the near-invisible stalk of the restaurant hangs in one of the triskelion voids of the mountain to the traditional ascent trail, where they can make those few last halting steps that induct them into the proud fraternity of those who have conquered the mountain. Wnt (talk) 16:55, 17 January 2017 (UTC)

Well I think Wnt has a point that a lot of people are already getting a lot of support, and yes not without controversy for numerous reasons but the fact remains they are doing so. But as I mentioned above, you'd still need a reason why the drones are a better choice than Sherpas doing the same work (presuming they can but it would seem they can for stuff Wnt suggested), and probably a reason they agree with. Given the current state of drone technology, I don't see how that's the case. Nil Einne (talk) 15:38, 17 January 2017 (UTC)

@Wnt: Do we have to use a helicopter rotor (or something similar) for lift? Drones don't have to be conventional quadcopters, right? Wouldn't an airship-like drone that contains a lifting gas that is lighter than air be a good idea? See also Atmospheric satellite, Geostationary balloon satellite, High-altitude platform station, Superpressure balloon and even Aerobot. (((The Quixotic Potato))) (talk) 00:32, 19 January 2017 (UTC)

January 16

Why is the lymphatic system not symmetric in the body?

Why the lymphatic system is not symmetric in the body? I mean that the right side responsible for the right limb only while the left side responsible for the entire body.(Btw, is it the only system in the body that it is not symmetric or there are additional systems like that?) 93.126.88.30 (talk) 00:41, 16 January 2017 (UTC)

There are many, many systems that are not symmetrical. Try putting a mirror to your face so that you are looking at the left (or right) side of your face replicated - you will hardly recognise yourself. Have a look at the fluctuating asymmetry article. DrChrissy ^(talk) 00:46, 16 January 2017 (UTC)

thank you, but I believe that the lymphatic system is asymmetric prominently as you look at the anatomy of the body. 93.126.88.30 (talk) 01:13, 16 January 2017 (UTC)

the heart isn't symmetric. the lungs aren't symmetric (shape, # of lobes). The spleen, the pancreas, the liver, the stomach, the intestines. The kidneys are only very roughly symmetrical (position, blood supply). The aortic arch. The left and right laryngeal nerves. I see no reason to emphasize the assymetry of the lymphatics more than any one of these. - Nunh-huh 02:09, 16 January 2017 (UTC)

I would guess that the relationship of the right lymphatic duct and left lymphatic duct should be evaluated in a broader context in terms of the asymmetry of great arteries and great veins, but I haven't thought this through. Wnt (talk) 12:36, 16 January 2017 (UTC)

The lymphatic system is initially symmetrical but becomes asymmetrical during the later stages of ontogenesis. Ruslik_Zero 13:19, 16 January 2017 (UTC)

Thanks - figure 33 in that source is especially useful. To quote another source, "The thoracic duct develops during the seventh and eighth week of gestational life from two vessels anterior to the aorta, which become the left and right embryonic thoracic ducts. The left one gives rise to the upper third of the adult thoracic duct while the lower two-thirds of the adult duct arise from the right embryonic thoracic duct."[15] The right thoracic duct retains its outlet, though, and continues to pass lymph from the parts that didn't degenerate or fuse, i.e. bronchomediastinal trunk, subclavian trunk, and jugular trunk ... and in some individuals, the lower lobe of the left lung. Perhaps a closer look at that variation would shed some light into the process. It is striking that all the lymphatic and circulatory structures tend to be variable and to develop such asymmetries, as faithful servants of every variation of the developing body. There's also something of a comic resemblance of these duct outlets to an aspiration vacuum on a laboratory sink - I wonder to what degree the venous flow tends to suck the lymph out... funny thing is, central venous pressure is ~ 3 mm Hg, though jugular venous pressure is presumably often lower from being higher, and also has a relaxation phase. I wonder how congestive heart failure or even some poor sap just being hung upside down at a black site affects the lymphatic system... Wnt (talk) 17:21, 16 January 2017 (UTC)

Nobody has yet mentioned physical and functional asymmetry in the brain - see Brain asymmetry. DrChrissy ^(talk) 22:07, 16 January 2017 (UTC)

More extensive and in-depth discussions of functional brain assymetry asymmetry may be found in our article Lateralization of brain function. One of many examples of functional and structural assymetry asymmetry of the brain in that article is the placement of Broca's Area and Wernicke's Area - both of these are often found only in the left hemisphere. Many functional and structural brain asymmetries are discussed in the article. loupgarous (talk) 00:57, 17 January 2017 (UTC)

It amuses me that the question is about the asymmetry of the lymphatic system and Wnt's links show one blue link for the right side and one red link for the left side. Matt Deres (talk) 15:52, 17 January 2017 (UTC)

That's only because left lymphatic duct should be a redirect to thoracic duct, but isn't wasn't. - Nunh-huh 21:26, 17 January 2017 (UTC)

I couldn't decide what to do with that because the thoracic duct actually includes bits of both left and right; also there's an embryonic left lymphatic duct. But I didn't do anything and you did, so you rightly get the say! Wnt (talk) 23:50, 17 January 2017 (UTC)

@Nunh-huh and Vfrickey: Please! Only your butt can be assymetric. Wnt (talk) 21:56, 17 January 2017 (UTC)

Thanks for the catch, Wnt. That was my brain on antihistamines (I've just edited my remarks with a line through my spelling errors as an acknowledgement of my carelessness). loupgarous (talk) 23:40, 17 January 2017 (UTC)

What is the reason that chewing gum causes to appetite?

I'm looking for the physiological reason why chewing gum is a trigger for hunger? 93.126.88.30 (talk) 01:07, 16 January 2017 (UTC)

Googling "chewing gum is a trigger for hunger" returns several sites that claim that the production of saliva triggers the digestive system into thinking that there is food to be digested, making you hungrier. Rojomoke (talk) 03:26, 16 January 2017 (UTC)

I'll vouch for that. ←Baseball Bugs ^{What's up, Doc?} carrots→ 03:36, 16 January 2017 (UTC)

Also, the taste of sweetness, whether sugar or a substitute, may cause the body to anticipate digestion and release insulin, leading to lower blood sugar and hence hunger. A good test to distinguish this from the other reason would be to chew a type of gum with no sweetener. StuRat (talk) 07:37, 16 January 2017 (UTC)

According to early advertisements for Doublemint gum, ("double-strength" peppermint) stimulates salivation, aiding digestion -- not to mention soothing throats and mouths, quenching thirst, promote weight loss, slow tooth decay, make the day go by faster, soothe the tired and the nervous, have more fun, make you more attractive to the opposite sex, ... [16] 107.15.152.93 (talk) 12:16, 16 January 2017 (UTC)

...And who can forget this immortal quote: "I'm the Court Jester, and Wrigley's is the Court 'Digester'"[17] 107.15.152.93 (talk) 12:16, 16 January 2017 (UTC)

Lower sex drive during the daytime,higher sex drive at night

Do people have a lower sex drive during the daytime, and a higher sex drive during the night?Uncle dan is home (talk) 18:53, 16 January 2017 (UTC)

Nocturnal penile tumescence ("morning wood") and nocturnal clitoral tumescence seem to support that idea. From an evolutionary POV, before artificial lighting, there wasn't much else one could do to ensure the survival of one's genes at night, in the dark, other than sleep, so this was a good time for mating, while daylight hours were precious, and every minute needed to be spent hunting, gathering, making tools, scouting, etc. (After the discovery of fire, it was possible to do some things by firelight, but there's also a cost to that, such as the time taken to gather, break up, and dry the wood and the effort to light it, so it might be better to save the dry wood for emergencies, like cold or animal attacks, than keep the fire going all night long, every night.) StuRat (talk) 19:12, 16 January 2017 (UTC)

The overlapping articles Libido and Sexual desire list many contributory factors but do not claim a causative correlation with a person's Circadian rhythm. One's particular social demands and opportunities, which are very different for modern or prehistoric man, shape opportunities to act on or think about hormonal drives. Blooteuth (talk) 21:52, 16 January 2017 (UTC)

NPT and NCT are known to be signs of REM sleep: if you have any references to support their correlation with "higher sex drive during the night", StuRat, please provide them.

Likewise, your remarks about an evolutionary connection to prehistoric life activities sound superficially plausible – not surprising, since you're evidently reasonably intelligent and broadly knowledgable – but without references to or citations of any scholarly investigation into the subject, or obvious pointers to subjects that others can follow up, they are no more than your personal musings. Scientific references on the Science Refdesk, please. {The poster formerly known as 87.81.230.195} 2.122.62.241 (talk) 10:55, 17 January 2017 (UTC)

Yes, StuRat's proposed explanation sounds a lot like a just-so story, and is contradicted by the linked articles, which state that they have nothing to do with libido, but are physiological phenomena resulting from changes in brain activity during sleep. Penile or clitoral erections can occur without sexual arousal. --47.138.163.230 (talk) 01:40, 18 January 2017 (UTC)

If you mean the articles I linked to, they do not "state that they have nothing to do with libido". The first article states "REM sleep may allow testosterone-related excitatory actions to manifest as NPT", which sure sounds like they are describing sexual arousal. StuRat (talk) 03:05, 18 January 2017 (UTC)

Physio-chemically, excitation is not the same as psycho-sexual arousal. μηδείς (talk) 16:47, 18 January 2017 (UTC)

There's also nocturnal emission. Are we also going to argue that this has nothing to do with sexual arousal ? StuRat (talk) 22:44, 18 January 2017 (UTC)

January 17

Three objects rearranged

We stack three ceramic pieces in the washroom and put a bar of soap on top. They are constantly being rearranged. Each piece can be upside down or not, and in any position (top, middle, bottom). How many different configurations are there? Many thanks to anyone who can help. :) Anna Frodesiak (talk) 00:29, 17 January 2017 (UTC) Can't you just tell your family to leave things alone so you don't have to come here and give me a headache before going to bed - hee hee. DrChrissy ^(talk) 00:55, 17 January 2017 (UTC)

DrChrissy, you can't tell them anything. They talk back. :) Anna Frodesiak (talk) 08:43, 17 January 2017 (UTC)

Think I will stick to my cats then! The only things they move around is the food in their bowls! DrChrissy ^(talk) 19:33, 17 January 2017 (UTC)

Anna, if the bar of soap is also considered in this calculation and considered to be placeable upside-down or right side-up, then there are 2x2x2x2 or 16 possible combinations. If you're considering only the ceramic pieces depicted in the graphic, those can be organised in 2x2x2 or 8 possible combinations. loupgarous (talk) 00:36, 17 January 2017 (UTC)

Hi loupgarous. No soap in the problem. Eight? That doesn't seem possible. Again, each can be upside down, and each can be in any position (top, middle, bottom). Are you absolutely sure? Best, Anna Frodesiak (talk) 00:45, 17 January 2017 (UTC)

48. Six orders (3×2), multiplied by 8 (2³) inversions. Andy Dingley (talk) 00:47, 17 January 2017 (UTC)

E/C :I'm not considering the soap. Each object can be in 2 orientations (upsidedown or right side up) and there are three pieces so there are 2³ orientations = 8. The pieces can be in 3 places so the number of places combinations is 3² =9. 8x9 = 72 total combinations. DrChrissy ^(talk) 00:49, 17 January 2017 (UTC)

Looks like Andy and I agree about the inversions, but disagree about the orders. DrChrissy ^(talk) 00:51, 17 January 2017 (UTC)

Pick a piece. One of three. Put it in a pile.

Pick another piece. One of two remaining. Put it on the pile.

Put the remaining piece on the pile.

Six. Andy Dingley (talk) 00:58, 17 January 2017 (UTC)

Good catch on places, Andy, Chrissy and Anna. There are 6 possible orders and 2x2x2=8 possible upside down/right side-up orientations in the array, giving a total of 6x8=72 different permutations of order x spatial orientation. loupgarous (talk) 01:14, 17 January 2017 (UTC)

6×8 = 48, not 72. StuRat (talk) 02:01, 17 January 2017 (UTC)

So, 72? That's the final number? No wonder it never looks the same. I must say, 72 really surprised me for only 3 objects stacked up. Thank you all! Anna Frodesiak (talk) 01:21, 17 January 2017 (UTC)

E/C I think I see why Andy and I might differ. Andy appears to be adding pieces to the pile. I have assumed that all 3 pieces are always in the pile, but only their places differ. DrChrissy ^(talk) 01:23, 17 January 2017 (UTC)

Yes, all three are always there. No more, no less. So, still 72? Anna Frodesiak (talk) 01:26, 17 January 2017 (UTC)

Nope, 48. See above. StuRat (talk) 02:01, 17 January 2017 (UTC)

Thank you, Stu, and thank you all, especially Andy who got it right first. Anna Frodesiak (talk) 02:18, 17 January 2017 (UTC)

You're welcome. (StuRat distributes multiplication tables to all concerned.) :-) StuRat (talk) 02:33, 17 January 2017 (UTC)

BTW, the number of arrangments of the 3 objects (ignoring the upside down options) can be calculated using factorial, hence $3!=3\times 2\times 1=6$. Nil Einne (talk) 04:39, 17 January 2017 (UTC)

• Or...

Position	Items (removed)	Orientations	Permutations
Top	1 (two)	2	2
Middle	2 (one)	2	4
Bottom	3 (none)	2	6

Combined permutations: 2 × 4 × 6 = 48   2606:A000:4C0C:E200:8097:8662:1582:8D5D (talk) 06:12, 17 January 2017 (UTC)

Thank you all again. Anna Frodesiak (talk) 08:43, 17 January 2017 (UTC)

• The number of permutations (the ordering) for 2-out-of-3 is (perhaps surprisingly) the same as for 3-out-of-3.

Build a pile of three. 6 permutations. Build a pile of two and "put the last one in an opaque box" - still 6, because putting the last one "on the top of the pile" or "back in the cupboard" is topologically the same thing. Andy Dingley (talk) 10:34, 17 January 2017 (UTC)

Right. Without the "orientations" multiplier (2x) in the table above, the top permutations would be 1 ... and one times whatever is whatever. 2606:A000:4C0C:E200:C196:3184:5BEE:2C53 (talk) 17:35, 17 January 2017 (UTC)

• You all seem to be missing ht point that 8 X 6 = 42. μηδείς (talk) 15:18, 17 January 2017 (UTC)

I hope that's a joke. StuRat (talk) 15:53, 17 January 2017 (UTC)

If it's a Douglas Adams joke, that should be 6 x 9. See here. Matt Deres (talk) 16:18, 17 January 2017 (UTC)

The way to keep that 'joke', such as it is, straight is to remember the third line by an anonymous author, the base is thirteen. Wnt (talk) 16:58, 17 January 2017 (UTC)

Thanks. And to think, for all these years I have been preaching heresy. This even came up last weekend. My dad asked me for help with the Sunday crossword; "What was the first error of THGttG, 8 letters?" I said fortytwo, and insisted on it, even when he said it was causing all sorts of problems. Turned out he was asking "what was the first airer of THGttG, which was BBCRadio. μηδείς (talk) 20:59, 17 January 2017 (UTC)

Inverse of pressure

I know that the inverse of speed is "pace" and the inverse of density is "specific volume". I was searching on Google for inverse of pressure but I can't find a term for that. I'm curious for what the term could be called; I can figure it out but it could take a bit of time and effort. Then I just found that the inverse of pressure is "specific surface area" which has units in m²/kg, while inversely kg/m² is the unit of pressure. I figured that out based from density differ in pressure only in power in the denominator part of the unit (kg/m² for pressure and kg/m³ in density) and 'volume' in specific volume downgrading to 'area' to make "specific area" and then I googled that and found the answer on myself. PlanetStar 05:35, 17 January 2017 (UTC)

So first of all I'm not sure that "pace" is really standard for "reciprocal speed". It's true that runners might say they're running at a "six-minute pace" (meaning six minutes per mile, i.e. 10 mph) but generalizing that into "pace = 1/speed" has the ring of WP:OR to me.

More important, pressure is not (properly) measured in kg/m^2. Pressure is force divided by area, not mass divided by area. You can measure pressure as kgf/m^2, where kgf is a rather nonstandard unit, "kilograms force", meaning the force needed to accelerate a one-kilogram mass at 1g.

The specific surface area article does not, unless I missed it, talk about 1/pressure. --Trovatore (talk) 06:04, 17 January 2017 (UTC)

I seen it on Google that pace can be the reciprocal of a speed in the context of running such as seen in the top result in that page. As kg and lbs are units of weight, the units of weight can be used in units of pressure, like pounds per square inch or psi, therefore they can be flipped to make square inch per pound or sip which is an imperial unit of specific area. And I don't see that it said that it is inverse of pressure in that article either, though in my opinion specific area is the inverse of pressure. PlanetStar 06:23, 17 January 2017 (UTC)

So the shibboleth I've been trying to avoid here is that you're confusing weight and mass. The reason I've been trying to avoid it is that people are a little too insistent on it, in a linguistic sense — in fact one of the meanings of "weight" in English is actually "mass", and there's nothing wrong with that.

But in any case kilograms, according to standard usage, are a measure of weight-in-the-sense-of-mass, not weight-in-the-sense-of-force, and kg/m^2 is not a unit of pressure, although kgf/m^2 is. --Trovatore (talk) 06:31, 17 January 2017 (UTC)

To expand on Trovatore's point, in strict, modern scientific use, mass (the amount of "stuff") is measured in kilograms, while weight (the force exerted by a mass due to gravity) is measured in Newtons. (Named after Sir Isaac Newton, rather than being a new, modern version of the ton). Imperial/customary units are more complicated, as a "pound" can be a unit of mass, or of weight, and other units of mass such as the slug. Iapetus (talk) 14:03, 17 January 2017 (UTC)

If a car was taken to the Moon where gravity is one-sixth that on Earth, the car would be easier to jack up to change a flat tyre because its weight would be one-sixth. Push starting the car would take the same effort that it takes on Earth, neglecting air and wind resistance and tyre rolling resistance, because the car has the same number of atoms (the same mass) that it has on Earth. Weight and mass are not interchangeable. Akld guy (talk) 18:55, 17 January 2017 (UTC)

The original question is sort of curious. Look up "square meters per newton" and there are a lot of weird answers. Like, a "brewster" is one trillionth of a m²/N, "a unit used in optics to measure stress-induced birefringence."^[18] Piezoresistivity tensors have units of reciprocal stress, i.e. this.^[19] Aquifer compressibility of fractured rock has the same.^[20] Ditto kinematic viscosity.^[21] And shear mode compliance.^[22] There are only a small number of actual hits for the phrase, but every one is inventive. My guess is that most folks invented a way to write these things in terms of pressure, but this is not physics as I've ever worked through it. Wnt (talk) 15:24, 17 January 2017 (UTC)

I googled "square meters per newton" and found one result that said is a unit of "pressure-viscosity coefficient" and then I googled that and found this page especially seen in Table 1. The page uses mm²/N. PlanetStar 23:16, 17 January 2017 (UTC)

I know for a long time that mass and weight are not interchangeable in terms of definitions, but some of the units like pounds can be used for both weight and mass. Pound would be an imperial unit of mass/weight while kilogram is a metric unit of mass/weight. One kilogram is 2.2046 pounds. But if we weigh an object on another world that has different gravity, they're weight would change but mass would stay the same. On the moon, one kilogram would equal to 0.37 pounds. PlanetStar 23:07, 17 January 2017 (UTC)

Let's avoid the confusing term "weight" altogether. Let's say "force", which is unambiguous.

It is not correct to say that pounds are a unit of both force and mass.

Rather, there are two different units, pounds-force (lbf) and pounds-mass (lbm). Pounds-force are a unit of force; pounds-mass are a unit of mass.

Either of them may, when context is sufficient to disambiguate, be referred to as "pounds". But that does not make them the same thing!

As for kilograms, by nearly universal agreement, they are a unit of mass, not force. There is a legacy unit, kilograms-force (kgf), which is still used in some niches. But that does not make specific surface area the reciprocal of pressure, because it is measured in m^2/kg, not m^2/kgf. --Trovatore (talk) 23:19, 17 January 2017 (UTC)

Do small children have more nerve endings per unit skin area than grown ups?

Small children seem to feel more pain during injections than grown ups, is that because they have more nerve endings per unit skin area? Count Iblis (talk) 08:33, 17 January 2017 (UTC)

That could be the case, but the more likely explanation is that grown-ups have simply built up more pain tolerance from all those small injuries in childhood and adolescence. 2601:646:8E01:7E0B:F88D:DE34:7772:8E5B (talk) 09:40, 17 January 2017 (UTC)

The articles Pain and Pain in babies (and their references) might be good places to start. We do not (as yet) have an article Pain in children. Also Nociceptor and Nociception. {The poster formerly known as 87.81.230.195} 2.122.62.241 (talk) 11:06, 17 January 2017 (UTC)

The answer is surely to be found here (PubMed), but you need some additional terms for an inspired search. So far, I haven't thought of what they are. Certainly I agree this is the case, though - I remember that as a kid if I went up to climb the stairs normally and I banged my shin on it (even with carpet around the edge of the step!), I would fall to the ground screaming, and that was no act! I remember once it left a tiny little bruise and I thought my leg was going rotten, but usually it didn't. Now I find bruises on my shins and I have no idea how it happened. (It is possible that the biology of bone growth had something to do with this, but still, the middle of the shin is far from the epiphyseal plate) Wnt (talk) 14:34, 17 January 2017 (UTC)

There is also Psychogenic pain, to wit, "physical pain that is caused, increased, or prolonged by mental, emotional, or behavioral factors." (emphasis mine). A person's attitude towards the event, or internal mental state at the time of the event, can effect in a very real way how much pain they perceive. People who are fearful of the shot may report higher pain levels than those who are not. This article reports that "...distraction ... significantly reduced pain perception. There were no interaction effects of either age or gender. Fear was a significant covariate, but distraction was effective even when fear was not held constant." That is, age was not necessarily a factor, but both attentiveness (or distraction) and fear were correlated to pain perception. --Jayron32 15:38, 17 January 2017 (UTC)

If the number of nerve endings doesn't increase as we grow, then logically, we have fewer nerve endings per surface area (skin) as we expand (grow). 107.15.152.93 (talk) 17:20, 17 January 2017 (UTC)

On average, sure, but do keep in mind e.g. Allometric Growth. An infant's head is far larger, proportionally, than an adult's [23]. It is entirely logically possible that nerves would remain equally dense in some areas (e.g. finger tips), but become far less dense in others (e.g. back). SemanticMantis (talk) 18:57, 17 January 2017 (UTC)

Yes, a little bit, if I'm reading this study correctly [24]. The abstract says:

“ Significantly higher intraepidermal fiber densities were seen in the youngest group ”

Note that "significant" does not mean the difference is large. If you look at Fig. 3, you'll see the difference is actually very small. The youngest cohort analyzed was age 10-19, so it's entirely possible that there are bigger differences in younger children. I found this paper with this search of google scholar [25], I suspect adding in other terms (e.g. child, infant, etc) or looking further down the list may get you something more clear and substantive. SemanticMantis (talk) 19:14, 17 January 2017 (UTC)

A fun trick related to this is the following: Get a "victim" to hold out their arm in front of them with the palm facing upwards. Tell them to keep their arm straight and close their eyes. Start very, very slowly to trace one of your fingers from the wrist towards the elbow joint. Then instruct the victim to tell you when they think your finger has reached the elbow joint. I won't spoil the surprise! DrChrissy ^(talk) 20:07, 17 January 2017 (UTC)

Do humans ever crave romaine lettuces and tomatoes?

For some reason, humans often say they crave sweets. But then when they go into specifics, they mean colorful baked pastries and candies and soda pop. I've never encountered one who has a fruit craving. "I want to eat a banana right now. I need potassium!!!" When it's a fat craving, they eat hamburgers and French fries, not "I need an avocado. Must have an avocado." Or let's say a person needs something to munch on constantly, but then eats a whole pack of cookies. If the cookies were swapped for a whole head of washed Romaine lettuce, then it'd probably take the same amount of time to munch on, and the person may absorb in water and usable nutrients. Why are fruits and vegetables not attractive? Do they ever induce cravings? 66.213.29.17 (talk) 17:58, 17 January 2017 (UTC)

Our Food craving article should be of interest. --107.15.152.93 (talk) 18:21, 17 January 2017 (UTC)

"Why are fruits and vegetables not attractive? Do they ever induce cravings?" Sorry, that's just not true. For example right now I'm really craving an apple.

We have articles on food addiction and Sugar#Addiction.

You also may enjoy reading about comfort food, Essential_nutrients, and recall that salt is essential for life. Lots of people eat lots of different things, and have lots of different preferences. We do have a nice Index_of_sociology_of_food_articles, many of which discuss how certain foods get treated differently in different cultures. SemanticMantis (talk) 18:52, 17 January 2017 (UTC)

• I crave orange juice, pasta, and pickles. That's why I am having bariatric surgery on Friday. μηδείς (talk) 20:50, 17 January 2017 (UTC)

"I want to eat chocolate right now. I need phytonutrients!!!" 2606:A000:4C0C:E200:C196:3184:5BEE:2C53 (talk) 20:55, 17 January 2017 (UTC)

The answer likely has to do with our evolutionary history. When our cravings evolved, we were getting way too much fiber, fruit, and veggies and found it quite difficult to get enough protein, fat, carbs, salt, and sugar (fruit of that era had just a tiny bit of sugar). So, there was no need to develop cravings for things we already had too much of. Fruits and veggies just became what they had to eat when there was "nothing better to eat", which was most of the time. But when they were lucky enough to kill something, they needed to eat all they could, and not fill up on fruits and veggies. StuRat (talk) 22:27, 17 January 2017 (UTC)

Our ancestors lived in a World where there were no supermarkets and fast food restaurants, also before the invention of agriculture, you had to spend a lot of time finding edible fruits and vegetables, and what you would find didn't look like what we're used to eating today. The craving we have today for junk food evolved to allow us to select the very specific edible and nutritious foods out of everything that grows in Nature. This leads today to a very strong attraction to modern fast foods containing an unnatural amount of salt, sugar, and fat, which is going to be the cause of death for most of us.

The sense of taste we have for salt sugar and fat gets less sensitive the more you eat of foods containing a large amounts of them. If you start to eat only healthy foods and stop adding sugar and salt to your food, your sense of taste will recover and you'll be able to sense the taste of vegetables and fruits much better. You can then find eating a banana just as tasteful as what eating a candy used to be like when you were still eating junkfoods. Count Iblis (talk) 23:33, 17 January 2017 (UTC)

Yes, I've mostly stopped eating beef, and now it tastes like blood, whenever I do eat it. StuRat (talk) 00:26, 18 January 2017 (UTC)

• People who go on long backpacking trips often come out with tremendous cravings for fruits and vegetables, to such a degree that "all you can eat" salad bars are not viable in places that host large numbers of backpackers. I have also myself experienced strong cravings for fruits and vegetables while recovering from a cold. My personal belief is that these are basically potassium cravings, but that's really just speculation -- there is no doubt about the reality of the cravings, though. Looie496 (talk) 15:48, 18 January 2017 (UTC)

• Pica can be caused by a nutrient deficiency. Also, see specific appetite. StuRat (talk) 22:49, 18 January 2017 (UTC)

Were moonwalkers allowed to keep any pieces of it?

Were they given/allowed to keep a small souvenir? Sagittarian Milky Way (talk) 22:16, 17 January 2017 (UTC)

Apparently not. [26] The things are apparently absurdly valuable - $50,800 per gram! There are a lot of stories about NASA trying to track down rocks they gave to every state and most countries that apparently have turned into the tokens of some preposterous international financial board game. Wnt (talk) 23:57, 17 January 2017 (UTC)

Yes. Apollo astronauts were allowed to keep a few rocks as lunar souvenirs, under the condition that they would never be sold but instead passed down from generation to generation. [27] In 2012 Barack Obama signed a bill into law granting NASA's Mercury, Gemini, and Apollo crew members "full ownership rights" to the artifacts they received and retained more than 40 years ago. The legislation (H.R. 4158) was authored in response to recent challenges raised by NASA's General Counsel and Office of Inspector General (OIG) over the attempted sale by several astronauts of their mementos.[28] --Hillbillyholiday ^talk 00:51, 18 January 2017 (UTC)

Reading that article, it says "The bill doesn't apply to the mementos astronauts brought from Earth to fly as souvenirs in their personal preference kits, and it explicitly excludes "lunar rocks and other lunar material." - so you're wrong.

The short answer seems to depend on the minimum mass of a "piece" of the Moon - if you're an Apollo astronaut, you get to keep dust sticking to your gear during your mission, and even incorporate it in privately-owned works of art. Our article on Apollo 12 astronaut Alan Bean refers to Bean's paintings of scenes from the Apollo missions; Paul D. Spudis, a senior staff scientist at the Lunar and Planetary Institute, Houston, Texas, USA (writing in "Can You Legally Own a Piece of the Moon?", an article in Air and Space Magazine) says that Bean is said to mix lunar dust which had stuck to his space suit and been recovered after the mission in the paints used in some of those paintings. NASA doesn't seem to have asked for the remaining dust, the paintings incorporating them, or a cut of Bean's profits from sales of those paintings.

Anything larger than that is held to be US Federal government property and cannot be owned by anyone as private property. American space writer James Oberg reported in "Astronauts, Cronkite To Get Moon Rock Plaques", a short article on the NBC News website that "The federal government forbids private ownership of any Apollo sample," and that the lunar samples included in commemorative plaques presented to astronauts active from Projects Mercury to Apollo, and the CBS News anchorman Walter Cronkite (who was on the air for 27 of the 30 hours the Apollo 11 astronauts were on the lunar surface) remained the property of the US National Aeronautics and Space Administration ( NASA). Oberg elaborated "...the honorees or their families will select in coordination with NASA a museum or some other educational institution where the awards will be on display in their name." So these are loans of lunar rock to various museums made by NASA in the names of the various honorees. loupgarous (talk) 00:55, 18 January 2017 (UTC)

Ah, I missed that bit at the end. But if the Time article is to be believed, it seems they were given souvenir samples, though they may not be true "owners". I definitely read somewhere that Armstrong managed to smuggle back a few moon-pebbles up his arse, discarding them in disgust after it was conclusively proved to him that the Apollo missions were indeed fake. --Hillbillyholiday ^talk 01:08, 18 January 2017 (UTC)

That fringe theory was debunked years ago by several successful reflections of laser light from reflectors left by Apollo missions to enable precise seismographic measurements as well as measurement of the distance between the Earth and Moon. Several researchers with no connection to NASA or the US federal government have conducted these experiments successfully. loupgarous (talk) 01:54, 18 January 2017 (UTC)

You're saying they used lasers to prove Armstrong didn't actually put moon-rocks up his bottom? --Hillbillyholiday ^talk 02:06, 18 January 2017 (UTC)

If you really believe the Apollo missions were faked, you should sue your educational system for fraud. ←Baseball Bugs ^{What's up, Doc?} carrots→ 08:31, 18 January 2017 (UTC)

If you really believe I really believe the Apollo missions were faked, you're plain nuts. --Hillbillyholiday ^talk 09:11, 18 January 2017 (UTC) (Do you also believe I missed the logical incompatibility between these two propositions: a) Armstrong returned from the moon with rocks up his arse; b) Armstrong thought the moon landings were faked? Hint: deliberately self-contradictory statements are often used in jokes.)

Well, your humor is too subtle for my feeble brain. But it's good to know that even a hillbilly is smarter than the presumably educated individuals who've convinced themselves that the moon landings didn't happen. ←Baseball Bugs ^{What's up, Doc?} carrots→ 12:21, 18 January 2017 (UTC)

January 18

Mass, space etc

Space cannot exist without mass. So, before the big bang, there was no space?? If so, where abouts (ie in what existence) did the big bang occur? Also, what happened to all the negative matter/energy that must have been created also? --213.205.192.126 (talk) 00:24, 18 January 2017 (UTC)

There's a slightly-fringe theory (called Zero-energy universe) that the negative energy is in gravity and space itself. The standard theory for the origin of space-time doesn't require any previous existence, though it doesn't preclude the possibility. Dbfirs 00:49, 18 January 2017 (UTC)

Space cannot exist without mass. General relativity doesn't require mass-energy to exist: see empty universe. Models of the Big Bang don't necessarily say there was no space prior to it, just that the universe was incredibly dense. We deduced that the Big Bang happened by simply extrapolating backwards the observed expansion of the universe. Eventually we get to a point where the currently-understood theories of physics blow up and stop working. Figuring out how to describe the universe before that point is one of the motivations behind the search for a theory of everything. --47.138.163.230 (talk) 01:57, 18 January 2017 (UTC)

The conventional answer to the question "Where did the big bang occur?" is "Everywhere," because at the time of the putative "Big Bang" (which was also the start of Time itself) all space was compressed into a single point, from which it subsequently expanded, initially by Inflation.

Negative energy exist as a mathematical concept in a similar way to deceleration being a negative acceleration; it is also applied to other more exotic concepts (as the article explains), but these may not be quite what the OP envisaged.

The question of "where did all the antimatter go?" (since current theories say that equal amounts of matter and antimatter should have been created) is perhaps the largest (in both senses) unanswered puzzle in astrophysics today: anyone who succeeded in solving it would be awarded a Nobel Prize, amongst other accolades. {The poster formerly known as 87.81.230.195} 2.122.62.241 (talk) 12:43, 18 January 2017 (UTC)

Small quibble: The Universe need not have ever been compressed to a single point. If the size of the universe is infinite, it has always been infinite, and the Big Bang was simply the moment of maximum density. Someguy1221 (talk) 16:09, 18 January 2017 (UTC)

How loud and "shaky" is an H-bomb at various distances?

Shaking from air-transmitted sound like infrasound or a subwoofer, not earth-transmitted earthquake (which would require exploding in or at least near the ground I think) Sagittarian Milky Way (talk) 01:10, 18 January 2017 (UTC)

You need to rephrase this question so that it makes sense.--Aspro (talk) 01:20, 18 January 2017 (UTC)

Better? Sagittarian Milky Way (talk) 02:01, 18 January 2017 (UTC)

To give you an idea of how "shaky" thermonuclear weapon ("H-bomb") detonations are, according to our article on the first thermonuclear detonation, the first indication outside the US military and United States Atomic Energy Commission was a seismic signal detected thousands of miles away at the University of California at Berkeley. California, USA. Co-designer of the weapon Edward Teller read the seismograph and immediately informed a colleague at the USAEC's nuclear weapon design laboratory at Los Alamos, New Mexico, USA four hours before official news of the successful detonation reached the continental United States by an unclassified telegram reading "It's a Boy".

Specific answers to your questions can be found in the US National Nuclear Security Administration reference work The Effects of Nuclear Weapons by Samuel Glasstone and Philip J. Dolan. Chapter 1 of that book, "General Principles of Nuclear Explosions" should give you enough comprehension of how thermonuclear devices behave to let you use the rest of the book to answer your question. loupgarous (talk) 01:38, 18 January 2017 (UTC)

I will read that. (when it finishes downloading) Sagittarian Milky Way (talk) 02:03, 18 January 2017 (UTC)

• ? Berkeley isn't "thousands of miles away" from New Mexico; or am I thinking of the wrong bang? Where was the news before it reached the continental United States? —Tamfang (talk) 08:47, 18 January 2017 (UTC)

• The colleague was in New Mexico. The Ivy Mike test was way out in the Pacific. ←Baseball Bugs ^{What's up, Doc?} carrots→ 09:18, 18 January 2017 (UTC)
• OK. Just for clarity's sake, the Ivy Mike test of the first thermonuclear device was held on Elugelab atoll - a few thousand miles from North America. loupgarous (talk) 14:02, 18 January 2017 (UTC)

• Nuclear explosions produce considerable infrasound, which is one of the ways that they can be detected, at least in theory. There is a global infrasound monitoring network, but I can't find any public data about what a nuclear explosion looks like to them (they are looking for illegal atmospheric nuclear tests, although they can pick up underground tests). However, 17 of the stations heard the infrasound from the Chelyabinsk meteor explosion, which is probably similar to a small nuclear explosion - the furthest station to hear it was in Antarctica. It produced a 17 minute long soundwave at around 1-2 Hz. You can hear a sped up version here. Smurrayinchester 14:20, 18 January 2017 (UTC)

Binomial badgers

Why is badger called Meles meles? DuncanHill (talk) 02:38, 18 January 2017 (UTC)

I think this is common, for the most common or first-named animal to have the same species name as the genus name. That way they don't need to find some unique characteristic to name that species after. Another way to go is to make the species name something like "vulgaris", meaning common, but if they become less common in the future this name will no longer be accurate. StuRat (talk) 02:47, 18 January 2017 (UTC)

Yes, but why Meles? That is to say, I am perfectly well aware that binomials are often duplicate (I am, after all, over 12 years of age), but what is the significance of Meles? DuncanHill (talk) 02:53, 18 January 2017 (UTC)

The European Badger was originally named Ursus meles by Linnaeus (see Mammalia in the 10th edition of Systema Naturae), who had mistaken the badger for a type of bear. This was changed to Meles meles by Brisson four years later. "Meles" means "badger" in New Latin. So basically, Linnaeus published the first taxonomic description of this species, saying it is a "bear badger", only for Brisson to point out that it is, in fact, a "badger badger". It is common practice that when a species is relocated to a new genus, the species name is left unchanged. Now, we could ask why Brisson didn't use a different name for the genus (Linnaeus heavily avoided double naming like this), and if there's an answer, it's probably in one of the two works he published in 1762, which are in latin. My guess though, is that he simply states the new name without saying why he likes double-names. Someguy1221 (talk) 02:57, 18 January 2017 (UTC)

Thanks, that's more what I was looking for. Now, how did meles come to be badger in New Latin? Our article on Meles meles suggests that meles means "marten or badger" in Latin, and I find it hard to believe that the Romans did not distinguish between the two. DuncanHill (talk) 03:22, 18 January 2017 (UTC)

• Pliny the Elder in Natural History first records the badger as Ursus meles, i.e. "honey-eating bear", according to this site Though I can't find the exact use of ursus meles in the Badger section of Natural History, its commentary uses meles: "There has been some difference of opinion respecting the identity of the animal, which Pliny calls "meles;" by some it has been supposed to be the polecat, or else the weasel."(Bostock, 1855) "Meles" was certainly called that before Linnaeus's description, as the word is analysed in Isidore of Seville's Etymologies, which, as well as the honey-eating meaning, proposes a link to malum "round fruit". [29] --Hillbillyholiday ^talk 03:06, 18 January 2017 (UTC)

• Of note, mel and its various forms has meant "sweet" or "honey" in ancient Latin. Someguy1221 (talk) 03:47, 18 January 2017 (UTC)

*And ironically, neither meles meles or even meles meles meles is particularly known for eating honey, though they'll eat it if it's available. And the actual honey badger is not even in meles! Instead it is Mellivora capensis, or "capetown honey-eater". It's interesting how names change meaning over time. Someguy1221 (talk) 03:54, 18 January 2017 (UTC)

Not that honey badger gives a shit. 2601:646:8E01:7E0B:F88D:DE34:7772:8E5B (talk) 05:54, 18 January 2017 (UTC)

(Of tangential interest: Tautonymic binomial names are allowed for animals, but are explicitly forbidden for plants. So we have Gorilla gorilla but no e.g. Pinus pinus.) SemanticMantis (talk) 15:08, 18 January 2017 (UTC)

We even have a Gorilla gorilla gorilla. Iapetus (talk) 17:32, 18 January 2017 (UTC)

Major Major Major Major? --Jayron32 17:52, 18 January 2017 (UTC)

Buffalo buffalo Buffalo buffalo buffalo buffalo Buffalo buffalo? --Jayron32 17:53, 18 January 2017 (UTC)

Hatnote Warning: any reference to that damn Monty Python sketch would be completely inappropriate; this thread has already become exceedingly silly. 2606:A000:4C0C:E200:185C:A689:C3A8:9F8 (talk) 19:55, 18 January 2017 (UTC)

Battery as a blasting cap?

I just saw an amazing news item [30] - apparently the "e-cigarettes" some folks like to smoke can explode with remarkable power, knocking out seven of a guy's teeth, even putting a hole in the sink he was near. The injury reminds me of blasting-cap accidents, and the shape seems a little like a blasting cap (well, it's kind of big, more like a regular battery, or a finger, at 65 x 18 mm). So I gotta wonder... can you use a battery like this as a blasting cap? Now yes, it seems ridiculous at first, since the primary explosive inside a blasting cap has a very powerful shockwave, whereas you think of an exploding battery as being a confined gas bursting a container. But ... with a discharge this powerful, maybe it's more like an exploding-bridgewire detonator, which is a blasting cap. Though I'm not clear on whether that necessarily still uses primary explosive.

Where this gets fun is that the primary explosive is hazardous and troublesome for the hobbyist (or, ahem, knight-errant) to create, whereas these things have apparently saturated the countryside. ;) Wnt (talk) 17:49, 18 January 2017 (UTC)

This may lead you some interesting places. --Jayron32 17:52, 18 January 2017 (UTC)

• " just pulled off charger " is simple abuse of the battery. I have never seen or heard of any credible instance of a Li-po "incident" caused by use alone, only ever by either mechanical damage or in relation to charging. Heating the battery during charging, then pulling the high current of a vaping coil from it, will certainly be a high risk action.

That said, these batteries will easily deflagrate but will not detonate and the battery ought not to explode, as a result of external protection circuits and a vented design for the case - but corners do get cut, especially around vaping.

I omitted a source I'd meant to mention, where I found the size: [31] It explains the frequency of counterfeit "vaping" batteries was quite high at one point due to shortages, and remains pretty high in domestic Chinese markets for example. It will be interesting to see if this is such a case. Wnt (talk) 23:40, 18 January 2017 (UTC)

Veolia's is still one of the biggest fires involving them, and there's video too.

• http://news.bbc.co.uk/1/hi/england/lancashire/8404129.stm
• http://www.safety-managementuk.com/veolia.php

Andy Dingley (talk) 18:33, 18 January 2017 (UTC)

What you are asking is can you use an extreme "failure model" of a specific kind of battery as a blasting cap, the answer is no. Because that battery will NOT reliably fail that way, every time. Several years ago when I started playing with lipo powered remote control vehicles, helicopters and drones, after a while I had a pile of useless cheap batteries which I intentionally made fail, and let me tell you some did fail quite spectacularly and some just fizzled without as much as a little pop. So you "could" use one, but it wouldn't work I suspect more often than not. So could you "on purpose" design something like a lipo but make it so it DID fail spectacularly "on command"? Probably, but then just buy the blasting cap which is designed for that purpose from scratch. Vespine (talk) 22:16, 18 January 2017 (UTC)

Well, not every ... patriot has an easy time buying a blasting cap... Wnt (talk) 23:40, 18 January 2017 (UTC)

I should take note LiPo = Lithium polymer battery. Wnt (talk) 23:47, 18 January 2017 (UTC)

RC models generally use 'flat' batteries, wrapped to the necessary size from sheet and broadly rectangular in shape. These have different failure modes from canned cylindricals, such as the 18650. They're more susceptible to external damage, but if they start thermal runaway they burn with continuous gas production, rather than building up pressure and then bursting explosively. Andy Dingley (talk) 00:11, 19 January 2017 (UTC)

Endocrine and exocrine hormones

Is true to say that endocrine hormones are in the blood and exocrine hormones are outside of the blood? 93.126.88.30 (talk) 23:59, 18 January 2017 (UTC)

Matter is liquid... at zero temperature?

Have a read of this link: http://www.aleph.se/Trans/Global/Omega/dyson.txt

at section "F. Matter is liquid at zero temperature"

It basically explains how quantum tunnelling will result in the rearranging of atoms and molecules in a solid over a time scale on the order of 10^65 years, so that the solid behaves like a liquid.

What I'm puzzled by is why he qualifies it with "at zero temperature". Why does the logic depend on the object being at zero temperature?

101.178.204.3 (talk) 00:39, 19 January 2017 (UTC)