Wikipedia:Reference desk/Archives/Science/2013 December 6

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December 6

Why do peanuts make me thirsty ?

Note that I eat unsalted Spanish peanuts. I suspect it's the liner between the meat and the shell that does it, but want to confirm this and also know the mechanism.

Thanks, StuRat (talk) 08:45, 6 December 2013 (UTC)

Are you saying you eat the paper? μηδείς (talk) 18:33, 6 December 2013 (UTC)

The Spanish peanut's brown skin contains bitter astringent tannins, per http://naldc.nal.usda.gov/download/CAT83783188/PDF. -Modocc (talk) 20:36, 6 December 2013 (UTC)

Do you mean you become more thirsty that your companions that have consumed an equal amount of the same nuts, at the same sitting, or are you asking -why do you become thirsty? As you already know and appreciate, we can not give medical advice so I am hovering between the simple answer and go discus this with your qualified practitioner.--Aspro (talk) 20:53, 6 December 2013 (UTC)

Eating pretty much anything makes me thirsty. Hard to figure why Stu would find it unusual. But as you say, if he's got genuine concerns, he should go to a doctor and tell him what's up. ←Baseball Bugs ^{What's up, Doc?} carrots→ 22:00, 6 December 2013 (UTC)

Jeez, I doubt Stu has or asked about a medical issue. Anyway, see the article on astringency that I linked to. Wild persimmons are my favorite, since they are quite sweet when ripe, but will make your mouth feel dry. Peanut skins can do this too. -Modocc (talk) 22:10, 6 December 2013 (UTC)

So can the increased blood sugar level of a diabetic. Aspro's reticence is justified. If Stu wants to tell us he doesn't get thirsty when eats the same amount sans papers we can absolve him. μηδείς (talk) 22:21, 6 December 2013 (UTC)

I would think, on the face of it, that Stu does mean he gets more thirsty eating peanuts than other foods. But you guys are free to, you know... --Modocc (talk) 22:37, 6 December 2013 (UTC)

It kind of reminds me of the old, fake medical warning: "Do you suffer from loss of appetite after a heavy meal?" ←Baseball Bugs ^{What's up, Doc?} carrots→ 22:13, 6 December 2013 (UTC)

1) Yes, I eat the "paper", because in Spanish peanuts, unlike other types, it adheres to the meat and is therefore difficult to remove. And yes, they make me more thirsty than I would have expected, based on the quantity and lack of added salt.

2) The astringent property makes sense.

3) I don't see foods making people thirsty as a "medical problem". On the contrary, if there is a way to encourage people to drink more water, without increasing their salt intake, then this sounds like a good idea to me.

4) Note that not all foods make people thirsty. Foods which contain lots of water, like fruit, for example, may not. StuRat (talk) 09:49, 7 December 2013 (UTC)

Point 3 (see above). As I said, I'm am not going to get into a medical debate. Some medical conditions often only first surface to the practitioners awareness, after the the recognition of symptoms, that have temporal connection, that appear to be linked with the consumption a large hand-full of 'protein' rich peanuts alone -(i.e., without any other food types being consumed at the same time to slow digestion down). Peanuts are very rich protein source, compared to most other food types. Protein toxicity. Early detection, helps to prevent further damage by the adoption of dietary changes. By the way, if your over 45, you can save a load of money on GP visits, by checking your kidney function monthly, with over the counter Albustix Reagent Strips for Urinalysis, Tests for Protein available from your local drug store. Your Quack will use the same product but will charge an arm and a leg for the privilege.--Aspro (talk) 17:11, 7 December 2013 (UTC)

But does protein in the urine indicate a medical problem or is it normal to urinate excess protein and/or amino acids, when you eat more than your body can absorb ? (Note that I don't actually have protein in my urine, so this is not a request for medical advice, either.) StuRat (talk) 04:37, 8 December 2013 (UTC)

Excess protein would be called proteinuria and is an indicator for many medical disorders, ranging from kidney failures to ebola. Healthy human excretory systems break protein down into urea, so if there's excess protein in the excretion, it should be investigated by a nephrologist or another qualified medical professional. We have an article on proteinuria. Nimur (talk) 15:52, 8 December 2013 (UTC)

So any protein in the urine is abnormal ? How about amino acids ? StuRat (talk) 05:35, 9 December 2013 (UTC)

Yes, I don't think Stu's question invokes Kainaw's criteria. But increased thirst is indeed a symptom of various medical conditions. μηδείς (talk) 17:30, 7 December 2013 (UTC)

That would be increased thirst for no apparent reason, not when you eat Spanish peanuts. StuRat (talk) 04:32, 8 December 2013 (UTC)

The increased thirst of diabetes correlates directly to blood sugar level. It is not random; although people may, of course, be ignorant of its cause. 21:40, 10 December 2013 (UTC)

Diabetes, Sjögren's syndrome, power cuts, radiation sickness, MDMA abuse, diarrhea, watching beer adverts or watching Lawrence of Arabia or Ice Cold in Alex, primary polydipsia etc. The list goes on and on.--Aspro (talk) 16:38, 9 December 2013 (UTC)

Technique for avoiding nodding off

I was reading something about an engineer nodding off and causing a train crash,^[1] and it reminded me of what a mystery "daytime sleep" really is to me. It's one thing to go to sleep at night for hours, but how to explain routine sleepiness at classes, seminars, or (what matters) while driving, that strikes when there's no exceptional circumstance like staying up all night or jet lag, which seems like one single moment of unconsciousness can be enough to end it? (I've heard this called highway hypnosis but our article doesn't use the phrase that way) Especially, I was wondering whether the technique I've come to use myself works for other people, or is an example of any higher principle: specifically, I practice answering some question or other somebody might ask at a job interview. (Some crazy social test like "what's the most difficult thing you've ever done", explaining some past project, etc.) It seems crazy, but I've found that speaking just two or three sentences to rehearse such an answer - at times when no such interview was upcoming to which stress could be attributed - seems to absolutely, utterly, completely banish routine highway sleepiness, from the point of thinking about pulling off the side of the interstate to avoid falling asleep in the next minute, to not even feeling like sleep is an option. It feels about a hundred times more effective than loudly singing, hyperventilating, rolling the windows all the way down, or blaring music on the radio. (However, finding a political talk show on the radio can also be effective, depending on the topic) Is there some systematic explanation for this? Wnt (talk) 09:01, 6 December 2013 (UTC)

Sure. This sleepiness is probably an evolutionary response to boredom. That is, when there's nothing much to do, you might as well sleep, so you will be well rested when there is something that needs doing. Cats take this to an extreme.

Unfortunately, in the modern world, there are situations which are both boring and potentially dangerous, like driving. We are not well adapted to those situations. Thinking means you are busy doing something your body assumes must be useful, so it holds off on sleep until a better time. StuRat (talk) 09:15, 6 December 2013 (UTC)

Wouldn't there have been situations like that for thousands of years? Walking miles to a spring to collect water, looking for berries, even fishing in a place where you could be attacked by wild animals. -- Q Chris (talk) 11:04, 6 December 2013 (UTC)

Walking and searching both require using the brain, so you would stay awake there. Fishing could indeed induce drowsiness, at least once you have the line in the water and are just waiting for a bite. Fly fishing, on the other hand, where you cast continuously, would not. Guard duty is another notorious problem, whether in ancient times, while watching for enemy soldiers and wolves, or in modern times when watching CCTV monitors for signs of trouble. StuRat (talk) 09:18, 7 December 2013 (UTC)

The term for sleepiness is Somnolence, and while the Wikipedia article is a bit stubby, there;s plenty of resources out there that seriously study this subject. --Jayron32 15:21, 6 December 2013 (UTC)

PubMed redirects somnolence to sleep, but searching with the term in quotes and adding in microsleep does get me up to 10% or more relevant papers. Some interesting connections with the immune system, actually. Which makes me suspicious the glymphatic system could be involved (it sure feels like there's a pressure change involved when nodding off, doesn't it?) but I didn't find anything about that. Hmmm... curiously, I don't see any mention of my particular method of practicing responses on various lists of ideas I see online. [2] I still wonder if it would work for other people as well as it seems to for me. Wnt (talk) 06:05, 7 December 2013 (UTC)

Simulating incorrect vision?

My friend has perfect eyesight. I have pretty bad short sightedness. If my friend looks through my glasses does he get a good approximation of what I see, since it's sort of... overcorrecting the correction the lenses provide? If not, is there any way you could simulate this, with special lenses? 81.138.15.171 (talk) 10:58, 6 December 2013 (UTC)

To accurately simulate it you would need a lense which is the opposite. If you may have a -2 diopter concave lens (for example) your friend would have to wear a +2 diopter convex lens to get the same effect. If you give him your lenses to wear you are simulating farsightedness. Small degrees of farsightedness don't impact as much as nearsightedness, it is easier to hold a book slightly further away than it is to get close to distant objects! -- Q Chris (talk) 11:12, 6 December 2013 (UTC)

I would recommend against that kind of tomfoolery, as anecdotal experience tells me that it can be literally painful to look through lenses that are starkly different from your own (be they natural or artificial). ←Baseball Bugs ^{What's up, Doc?} carrots→ 21:58, 6 December 2013 (UTC)

It would have to be the opposite correction, as Q Chris explains. I don't know whether that's reliable way to simulate it. Accommodation may determine the result. It could also depend on what you want to simulate, with your case (near-sightedness) more likely to give the right result than trying the same for far-sightedness, because you want to take away part of the range, and we all have the same fixed limit for our upper range (no one ever needs to focus beyond "infinity"), but there's no equivalent lower limit where a further range would become useless: if you could focus on objects 2 cm from your eye, you'd never need a magnifying glass. So we would expect people with normal vision to have the same "far limit", and giving them glasses with a positive curvature would reduce their field of vision in a predictable way.

But that's just an assumption, to know if the result is at all accurate I would compare both your vision without glasses and his vision wearing the opposite glasses with an online simulator like this or a clip of such a simulation. And these by themselves give him already a good idea of what you see, without the need for glasses. If you google for myopia simulation you'll probably find more of them. Another option (if you want to try out the glasses idea) would be a simple eye chart to see if his vision is as bad as yours. Ssscienccce (talk) 14:17, 7 December 2013 (UTC)

Follow up to "Surface gravitation of "kissing" spheres"

Imagine two non-rotating black holes rushing past each other on a non-collision path. They both have a spherical event horizon when they are far away from each other. Based on the same Roche Lobe mentioned earlier, the event horizons ought to become non-spherical as they approach. The way I figure it, the event horizons should recede from each other. That should let you have access to a part of space-time previously inaccessible. Is that correct? Does it let you peek into the outer bit of a black hole, or does space on our side of the black hole stretch, or what? Tdjewell (talk) 13:32, 6 December 2013 (UTC)

Hmmmm, black holes aren't really known for a generous refund policy. Bear in mind that "orbits" near a black hole tend to end in sorrow - even a neutron star is surrounded by a photon sphere. Gravity and acceleration are more or less the same thing, and if acceleration isn't going to get you out, neither is gravity. Wnt (talk) 16:31, 6 December 2013 (UTC)

Binary black hole is this sort of situation. The black holes will not remain spheres in this situation, they will extend towards each other, (not recede) and may form a connecting tube, followed by merge. Any point beyond the event horizon will stay there, that is what event horizons are, the point of no return. If you can return, then it is not an event horizon. Graeme Bartlett (talk) 19:52, 6 December 2013 (UTC)

If the OP doesn't mind asking, and just from my own curiosity, what was the reasoning behind thinking they would recede from each other? μηδείς (talk) 02:16, 7 December 2013 (UTC)

I assumed the net gravitation towards one black hole would be offset by the other, so what used to be the event horizon would move closer to the black hole, because now you could escape because of the other black hole puling the other way. 96.241.147.59 (talk) 14:28, 7 December 2013 (UTC)

The important simplified measure is the gravitational potential, rather than the force. If the negative potential is greater than the mass energy in the object, then it would be past the point of no return. Graeme Bartlett (talk) 19:52, 7 December 2013 (UTC)

queer! .. wouldn't that mean for travelling light in an ideal theoretical case aiming right through the center of that double massive object, that it couldn't find into an orbit, thus would be `braked´ and take the mass-equivalent of its energy?! [In analogy to the tube through earth where a stone falls penduling to and fro the center until its potential energy is used up] .. All this sounds pretty much like thought experiments on the way to a macro-quantum-gravitation where I wonder what the macro-quantums might be in these cases .. O.-o ?! --84.137.115.34 (talk) 10:09, 8 December 2013 (UTC)

Do humans' body size increase gradually in recent thousands of years?

I just recalled a newspaper article says that humans' body size did increase, one evidence given is that modern adult can barely fit in a medieval armor. Is that true?--chao xian de lun zi (talk) 14:23, 6 December 2013 (UTC)

See the Wikipedia article titled Human height. You can also answer your question by typing "History of human height" or other similar searches into Google. --Jayron32 15:11, 6 December 2013 (UTC)

It's worth noting that our article, reflecting the present state of the literature, treats the subject without consideration of the role of the inheritance of acquired characteristics (transgenerational epigenetic inheritance). This is hinted at as a possibility, however, in recent reviews ([3]) because so many of the factors involved are circulating hormones that could affect epigenetic marks on genes within the gonads. As a result, though properly written, our article probably misses the most important mechanisms. Wnt (talk) 16:47, 6 December 2013 (UTC)

That is a design feature, not a flaw. Rmhermen (talk) 17:32, 6 December 2013 (UTC)

• Historically, nutrition has been the limiting factor in potential size at maturity. People from the same ethnic group, transported to an affluent nation, tend to outgrow those who stay in an impoverished homeland. This blog has some useful references. Human height mentions changes in growth trends in relation to nutrition as well, with significant increase in height before 1950 and stagnation since then. μηδείς (talk) 22:18, 6 December 2013 (UTC)

Is it dangerous to eat raw eggs?

Is it dangerous to eat raw eggs? --78.156.109.166 (talk) 20:37, 6 December 2013 (UTC)

Danger is a relative concept. Per Raw_egg#Contamination, 1/30,000 eggs are contaminated with Salmonella. μηδείς (talk) 20:43, 6 December 2013 (UTC)

It doesn't seem to bother the average weasel. ←Baseball Bugs ^{What's up, Doc?} carrots→ 21:55, 6 December 2013 (UTC)

Saying they are dangerous can be detrimental as well. Just ask Edwina Curry, she lost her post as junior health minister and broke up with John Major after mentioning salmonella! Ssscienccce (talk) 14:30, 7 December 2013 (UTC)

The other health risk (for consumers of vast quantities of raw egg) is biotin deficiency due to the presence of avidin in raw eggs. Cooking the eggs would denature the protein and render it inactive. - Nunh-huh 01:49, 7 December 2013 (UTC)

As the page lined by Medeis mentions, some eggs may be produced by vaccinated hens to reduce or eliminate the possibility they contain Salmonella. Some markets also sell pasteurized eggs, which will kill Salmonella without hardening the egg if the pasteurization was done correctly. Someguy1221 (talk) 01:59, 7 December 2013 (UTC)

μηδείς: Had a bad stomache recently and I often eat 'em raw. Someguy1221: Yea, already saw that. But why do they vaccinate if most bought raw eggs (at least in Denmark) has text that reads: Must be cooked to 75°C, else use pasteurized eggs? --78.156.109.166 (talk) 20:32, 7 December 2013 (UTC)

Who the hell cooks an egg to 75°C? Ever been to... a restaurant that serves breakfast? Sunny-side up for me, please. Doc talk 10:09, 8 December 2013 (UTC)

Yea, I don't get the point. Raw eggs have the texture of snot. Who wants that ? StuRat (talk) 06:04, 10 December 2013 (UTC)

Normal, non snot-attracted people mix raw eggs with something in a blender, making a rich shake. μηδείς (talk) 19:25, 10 December 2013 (UTC)

Self-healing cutting mats

Many cutting mats seem to claim to be "self-healing". I bought a cheap cutting mat on ebay and, unsurprisingly, it doesn't self-heal like the manufacturer claims. Does any mat? How? --78.148.106.99 (talk) 21:12, 6 December 2013 (UTC)

A simple internet search for 'self healing cutting mat' or I suspect any similar term will find our article Self-healing material as well as this non RS [4] which has some useful info in the comments and also links to [5] with again some useful comments. As well as a number of videos, most of them fairly adverty, but some have some useful info, e.g. [6] identifies [7] as one material used although I think arguably doesn't really meet our article's definition of self healing. Whether it meets yours I can't say as it was undefined although I assume you weren't expecting the mat to rejoin if cut in half (to be honest I don't think many of these mats will meet my definition either). Related searches will find more research on self healing materials (not necessarily for mats) such as this recent one [8]. Nil Einne (talk) 23:50, 6 December 2013 (UTC)

"Bridge" rectifier

I know what a rectifier is but I don't know why I sometimes see the word "bridge" applied. What is the word bridge doing there? Are there more than one type of single-phase full-wave rectifier of the which the one using four diodes is only one? --78.148.106.99 (talk) 23:34, 6 December 2013 (UTC)

Correct. There are bridge circuits that are not rectifiers; and there are rectifier circuits that are not bridges; and there are variants of both that use diodes (and others that use no diodes). When a circuit satisfies all criteria - built from diodes in a bridge configuration for the purposes of rectifying a signal, then it is a "diode bridge rectifier." Nimur (talk) 00:15, 7 December 2013 (UTC)

Geography question: which GNIS code should we use?

(Full details at Talk:Buena Park, California)

There are two different GNIS codes and altitudes for the city of Buena Park, CA:

https://geonames.usgs.gov/pls/gnispublic/f?p=132:2:533393829700819::NO:RP::
https://geonames.usgs.gov/pls/gnispublic/ (type 2409932 into the Feature ID box)
Feature Name: City of Buena Park
ID: 2409932
Class: Civil
Ele(ft): 72

https://geonames.usgs.gov/pls/gnispublic/f?p=132:2:533393829700819::NO:RP::
https://geonames.usgs.gov/pls/gnispublic/ (type 1652676 into the Feature ID box)

Feature Name: Buena Park
ID: 1652676
Class: Populated Place
Ele(ft): 75

So, which should we use? --Guy Macon (talk) 23:37, 6 December 2013 (UTC)

Your two links are identical... --Jayron32 02:53, 7 December 2013 (UTC)

This is Buena Park (second entry) :https://geonames.usgs.gov/pls/gnispublic/f?p=132:3:533393829700819::NO:3:P3_FID,P3_TITLE:1652676%2CBuena%20Park --Auric talk 03:09, 7 December 2013 (UTC)

Wait a minute, are we splitting hairs over 3 feet? The distance between your belt buckle and your head? Pick one and go with it. If someone else complains, tell them to find something greater injustice in the world, because this problem is pretty low on the "stuff that one needs to waste bits on the Wikipedia server" about... --Jayron32 03:12, 7 December 2013 (UTC)

Stating the elevation of an entire 10 square mile city to a precision of better than 10 feet is kinda stupid anyway. Suppose someone dumped a pile of dirt on the spot where the measurement is taken on one day and removed it again the next? Suppose they measured the elevation at City Hall, then built a new one after levelling the site or something....should we say that the entire city changed elevation? I'm quite sure there is much more than three feet of vertical elevation variation across the city! Personally, from a scientific/mathematical perspective I would change the article to say 70 feet in order to avoid implying more precision than is realistically possible!

If I had to guess as to why you're seeing two different numbers then I'd go with the guy who answered this question on "The straight dope" - which is that there isn't a standard way for people to describe the elevation of a city...and often it's just someone eyeballing it from a contour line on an outdated map. He found two different sources for the elevation of Denver that differed by 20 feet - and our article on Denver (wisely) specifies a range of elevations rather than a single number.

Truly - this is a waste of time. If you really want to improve the article, find a photograph of the place to stick in there - given the current state of the article, that would do more to improve it than almost anything else!

SteveBaker (talk) 06:41, 7 December 2013 (UTC)

The URL thing is weird. I thought that I had made a simple cut and paste error, but it turns out that the GNIS site gives you two different pages with two different GNIS numbers using the exact same URL. I fixed it by replacing the URLs with instructions on how to do the queries.

As for the importance of the elevation, those who think that getting it right is not important are welcome to not respond and move on to a question that they deem important. Some of us care about getting even small things right. See Talk:Slackware#ANNOUNCE: Slackware Linux Distribution 1.00 for one example. There is room in Wikipedia for both types of editor.

As for the speculation about eyeballing contour lines on outdated maps, the dataset GNIS uses is the USGS National Elevation Dataset. as it says at http://ned.usgs.gov/ , "The NED is a seamless dataset with the best available raster elevation data of the conterminous United States, Alaska, Hawaii, and territorial islands. The NED is updated on a nominal two month cycle to integrate newly available, improved elevation source data. The NED is derived from diverse source data that are processed to a common coordinate system and unit of vertical measure". Yes, modern cartography can indeed determine the average elevation of a city in the continental US within a meter. LIDAR is good enough to get you within a half meter or so.

Of course this being Wikipedia, what matters is what is sourced. In general, when we run into contradictory sources, we don't arbitrarily decide that the difference is unimportant and randomly pick one source.

I appreciate your time, but I am going to try another forum. Perhaps Wikipedia:WikiProject Maps. --Guy Macon (talk) 08:00, 7 December 2013 (UTC)