Wikipedia:Reference desk/Archives/Science/2017 January 14

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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) Dragons flight is correct, but I would like to add that it may be a good idea to ask the Dutch Society Against Quackery (Tgeorgescu is a member of that organization). (((The Quixotic Potato))) (talk) 00:47, 19 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 Siemens-info-line@bshg.com. 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)