Wikipedia:Reference desk/Archives/Science/2016 June 1

= June 1 =

Is our sweat salt because we eat too much salt?
The Yanomami Indians have an average intake of 50 mg of salt per day. They live in very hot and humid conditions, so they must sweat quite a lot. It's then impossible for them to lose the approximately 1 gram of salt per liter sweat like we do. This seems to suggest that the salt we lose in urine and sweat is just a way for the body to dump excess salt. Presumably, the salt concentration of sweat saturates at some level (say 1 gram per liter) if the intake is a lot more than 1 gram per day, and this is then the maximum amount of salt that the body can put in the sweat. So, is salty sweat really a sign that we're overdosing on salt? Count Iblis (talk) 01:28, 1 June 2016 (UTC)


 * The short answer is no. Climate adaptation plays a very large part, specifically: Most people have the ability to physiologically acclimatize to hot conditions over a period of days to weeks. The salt concentration of sweat progressively decreases while the volume of sweat increases.  Urine volume also reduces. . Salt in the sweat comes from the blood, sweat depletes blood sodium concentration but it is not the mechanism which the body uses for regulating blood sodium concentration, that would be the kidneys.  Vespine (talk) 02:41, 1 June 2016 (UTC)


 * As a type-2 diabetic who takes Jardiance I have been advised to consume as much water per day as possible, which is about 2 gallons. My lab results normally show a slightly too low sodium level, and I feel fine. μηδείς (talk) 03:48, 1 June 2016 (UTC)


 * Sweating isn't very effective in highly humid conditions. They might cool off in other ways, such as taking a dip in the river, or avoid activity in the hottest part of the day.  Also, I believe they live in the rain forest, where there is plenty of shade. StuRat (talk) 14:42, 1 June 2016 (UTC)


 * Mammals need sodium and chlorine, which do not necessarily have to come through eating salt, but salt helps. E.g. eating fried flesh only ensures enough salt on its own. See e.g. http://www.jstor.org/stable/27848175 . See also Health effects of salt: the evidence for "salt is bad" consensus is quite flimsy. Recent research suggests that eating too few salt is as bad as eating too much salt. Tgeorgescu (talk) 23:45, 2 June 2016 (UTC)


 * I believe the consensus was that "too much salt is bad", not that any salt at all is bad. And that consensus still holds, although the exact amount which is "too much" is debatable.  It's also been well known for a long time that too little salt is bad, but, for people on a Western diet, the chances of actually suffering from a lack of dietary salt is quite low.  This would require not eating restaurant meals, processed foods, or adding salt or salt-containing spices and condiments to any food. StuRat (talk) 17:28, 3 June 2016 (UTC)


 * See also http://www.dailymail.co.uk/news/article-2460992/Goats-defy-death-scale-dam-Italian-lake-Gran-Paradiso-National-Park.html, http://www.theguardian.com/environment/2010/nov/03/goats-italy-dam-precipitous-heights and http://www.bbc.co.uk/programmes/p027l3nk/p027l3fv . Tgeorgescu (talk) 23:56, 2 June 2016 (UTC)
 * I'm not going to try to find it at home with my slow Internet, but People's Pharmacy has an article stating the AMA disagrees with some British research. I wanted to propose the dispute be mentioned on Wikipedia.— Vchimpanzee  •  talk  •  contributions  •  21:54, 3 June 2016 (UTC)

A low salt diet is actually a high salt diet. Count Iblis (talk) 23:29, 3 June 2016 (UTC)

Meander vs the coastline paradox
I was recently reminded of the idea that a river will not run straight for more than ~10 times its width. I'm trying to reconcile that with the coastline paradox in my head. I keep coming back to "What is straight when you're referring to a river?" Am I not thinking about this the right way? Is that where the roughly part of the 10 times its width comes in? Dismas |(talk) 02:05, 1 June 2016 (UTC)


 * Is the Susquehanna River before the mouth straight enough to be called straight? It's pretty damn straight for a stretch that long. Sagittarian Milky Way (talk) 02:31, 1 June 2016 (UTC)


 * It's almost certainly just a "rule of thumb". I'm no river expert but it doesn't some like some general rule of hydrology. It would depend on many things, what the river bed is made out of to start with; a river between two cliffs could easily be straight for a long way, or would you then call it a creek or a stream? Vespine (talk) 02:55, 1 June 2016 (UTC)


 * There are any number of ways to make such a measurement well-defined. For example, from the middle of the river one might measure the longest line-of-sight distance that one can travel before reaching a bank and compare that to the shortest distance one can travel.  Whether any particular measure of straightness makes your aphorism approximately true, I don't know.  Dragons flight (talk) 12:02, 1 June 2016 (UTC)


 * The Hudson River at Poughkeepsie meets that criterion (as well as a stricter "best fit linear approximation of a section of midline that's completely in the river divided by average river width of said section of midline"). The Hudson River at Manhattan is even straighter but maybe not for 10 river widths. Sagittarian Milky Way (talk) 14:31, 1 June 2016 (UTC)

The coastline paradox applies to fractal or similar sorts of curves. The banks of a river would have that property just as coastlines do, but the length or straightness would be measured along the centerline&mdash;the set of points that each are equally near to the nearest point on each side. I think the operation of finding the centerline would damp out any fractal deviations mcuh smaller than the width of the river, so I think the centerline should be a more ordinary sort of curve. (I have not attempted to prove this mathematically, though.) --69.159.60.83 (talk) 06:21, 1 June 2016 (UTC)

We discussed definitions of river lengths last summer, ...is the length of a river well-defined? Nimur (talk) 14:04, 1 June 2016 (UTC)


 * Is there a source for this aphorism? I ask not because a source is needed to ask this kind of question, but because reference to the source would help us know exactly what it is supposed to mean.  John M Baker (talk) 14:09, 1 June 2016 (UTC)


 * Widely used, says google. Luna Leopold, says, . --Tagishsimon (talk) 14:27, 1 June 2016 (UTC)


 * Excellent! I know more about his father, but Luna was quite the scientist as well. Here is an excellent monograph detailing properties of stream channels, with some discussion of width and meandering. Lots of cool graphs with detailed measurements of many characteristics, across many scales. I cannot easily search it, unfortunately. For even more on the topic, here  is a nice compendium of accessible copies of his works, many of which touch upon this issue. SemanticMantis (talk) 14:43, 1 June 2016 (UTC)


 * I would expect there to be special geological cases where a river would remain straight for far longer. For example, say sedimentary layers change from hard to soft to hard, then uplift at one side turns all 3 layers on their side, so that now the soft layer erodes first, forming a straight river. A syncline is another case. StuRat (talk) 14:30, 1 June 2016 (UTC)


 * Do you have an example of an exception? The idea of exceptions has already been raised. SemanticMantis (talk) 14:43, 1 June 2016 (UTC)


 * See pic of the Ping River. StuRat (talk) 15:02, 1 June 2016 (UTC)


 * Mississippirivermapnew.jpg, not relevant at all. Maps at this scale never show detail of stream bed meandering. There are likely departures from that line on the scale of hundreds of meters, if not more. Nice try though. SemanticMantis (talk) 16:27, 1 June 2016 (UTC)


 * Look at this Google map of the Ping River, then switch to satellite view, and zoom in: . It's hard to see the river through the tree cover, but the tree line, following the river, is relatively straight in many sections. StuRat (talk) 20:00, 1 June 2016 (UTC)
 * That's better! SemanticMantis (talk) 14:35, 2 June 2016 (UTC)


 * Leopold's aphorism is given in SemanticMantis's first link, at page 53 (PDF page 18). On page 60 (PDF page 25), the article says that a straight channel is one with a sinuosity less than 1.5.  John M Baker (talk) 17:13, 1 June 2016 (UTC)
 * Thanks! I didn't have time to read at time of linking. As penance, here is the relevant quote from p. 53: In the field it is relatively easy to find illustrations of either meandering or braided channels. The same cannot be said of straight channels. In our experience truly straight channels are so rare among natural rivers as to be almost nonexistent. Extremely short segments or reaches of the channel may be straight, but can be stated as a generalization that reaches which are straight for distances exceeding ten times the channel width are rare.
 * This is also a great example of the value of collaboration in finding references! I skipped this question until User:Tagishsimon found the Leopold link, then I found a paper that contained the aphorism, then you found the aphorism itself. Good job all! SemanticMantis (talk) 17:25, 1 June 2016 (UTC)


 * I had a moment, so out of curiosity, I did a search for rift valley river and came up with the Narmada River (what the hell is a rift valley doing in the middle of India? Must look up...) On Google Maps it looks like this:  Is that straight for more than 10x?  I don't know.  In any case, not just any rift makes a straight river. Wnt (talk) 17:21, 1 June 2016 (UTC)
 * The Narmada rift zone was mainly active during the Mesozoic, although the rift faults show some signs of continuing activity. Mikenorton (talk) 09:17, 3 June 2016 (UTC)


 * That's a good contender at least. Zooming in, parts of the "straight" part would likely be classified as braided, you can see the multiple channels created by sandbars, a sort of reticulated effect. Actually I see suspicious discontinuities in the braiding, indicating that the photos were pasted together from different times or even different years. SemanticMantis (talk) 17:29, 1 June 2016 (UTC)


 * Looks like maybe the Sacramento River has a stretch here that is straight for more than ten times its length. John M Baker (talk) 00:12, 2 June 2016 (UTC)
 * Good find! But, being passingly familiar wit Sacramento, I wonder to the what extent the stream bed is human engineered. Note the river there is neatly sandwiched between 160 and river road, and see e.g. maps here for the extent of levees, channelization, weirs, etc deployed in the region. In short, I agree it's straight for more than 10x width, but I'm skeptical that the stream bed should be considered "natural" in that reach. SemanticMantis (talk) 14:29, 2 June 2016 (UTC)


 * Looking for more "rift valley rivers", I found the Jordan River and Luangwa River, both of which are quite convoluted despite the underlying geology. It seems apparent from inspection that once a river erodes and deposits enough of a floodplain, even with the straightest underlying geology, it is free to meander quite extensively. Wnt (talk) 00:26, 2 June 2016 (UTC)
 * Like this Vietnamese/Chinese river? The floodplain is ruler straight for 200 kilometers and fits in a 200 x ~3-5km rectangle but the river meanders extensively. Sagittarian Milky Way (talk) 19:27, 2 June 2016 (UTC)
 * Yes, it's almost as if one of the greatest living geologists/hydrologists of his era knew what he was talking about, perhaps more than the casual ref desk reader or responder! It's true he didn't have google maps to easily skim for counterexamples though :) SemanticMantis (talk) 14:29, 2 June 2016 (UTC)
 * Just because it's true doesn't mean it's a bad thing to test some examples and see how true it looks on the ground. It's harder to remember a principle than the physical sight of how it plays out on a satellite photo. Wnt (talk) 15:01, 2 June 2016 (UTC)
 * I think it's reasonable to test assertions by experts. And in this case, we're not really even challenging Leopold:  Some of the paraphrases on the Internet assert that there are no natural straight stretches of more than ten times a river's width, but he only said that such stretches are rare.  It seems the best candidates we have so far are the Sacramento and the Ping, but (as you point out) it's quite possible that the Sacramento is engineered, and it's hard to be sure about the Ping from the maps we have.  The Hudson is really straight at Manhattan, but not for ten river widths, and I don't see a comparable straight stretch in Poughkeepsie.  The Susquehanna is not all that straight.  The Narmada is pretty straight and arguably qualifies, although Leopold would probably call it a braided rather than straight river.  John M Baker (talk) 15:26, 2 June 2016 (UTC)
 * Oh yes, I was just teasing Wnt a bit, sorry if that wasn't clear. It certainly is interesting to look for exceptions, and it is good to note that this is not hard rule but a solid tendency. I had actually never even heard the assertion before, so I was very pleased to discover the scientific basis and original author of the conjecture/aphorism. SemanticMantis (talk) 15:56, 2 June 2016 (UTC)

Is this poodle-dog bush?
It's in a location where it might be found (the general area of Strawberry Peak off the Angeles Crest Highway; the Station Fire (2009) still being recent enough). The flowers look similar to what I see online. The leaves &mdash; well, they're not as pointy. Some pictures seem to show the leaves bent in the middle, which these are not, but maybe they open up sometimes. They have a similar sort of scalloping, with soft ridges purpendicular to the spine of the leaf. Does anyone know? --Trovatore (talk) 05:23, 1 June 2016 (UTC)




 * The leaves are generally not a great feature for plant ID. The margin and size can change with plant age and between individuals of the same species. Consider this young PDB - its leaves look much like yours, and are far wider than many of the pictures I see with a general image search. The curling response is related to drought tolerance, so drier plants will have more curl to their leaves. Anyway, for you specific case: maybe? If you have a closeup of the flower that would help. If the flower has the right number of petals and stamens, we can also tell it is broadly of the right shape and color, and since it is growing at the right location and blooming at the right time and has the right stature, I would be fairly confident that your photo is at least one of the Eriodictyon. SemanticMantis (talk) 12:54, 1 June 2016 (UTC)
 * OK, thanks, SM. Unfortunately I didn't take any closer pictures &mdash; this one is a result of looking through my shots for the one that had the most of it, closest, to crop.  I was really wanting to learn to identify it, so I don't have to be paranoid about all low-growing shrubs with purple flowers.
 * But come to think of it, while I think I know poison oak pretty well, it's entirely possible that I group some harmless sumacs in with it, and I'm mostly OK with that. --Trovatore (talk) 17:26, 1 June 2016 (UTC)
 * Haha prolific poison oak is one thing I don't miss about that region! I should amend my statement above though: leaf shape and size are not good ID characteristice. Leaf growth pattern (e.g. alternate, paired, etc) and Leaf are important parts of working through a taxonomic key. If you collect a sample, I'm pretty sure you could work through a key and be sure. SemanticMantis (talk) 17:38, 1 June 2016 (UTC)

Forgot substance
A few days ago I saw some Wikipedia article on a certain substance (forgot which) with an insane molecular formula. The numbers of oxygen, carbon and possibly nitrogen atoms were over 400, something like C350H600O700, perhaps there were other elements as well. The article also had an illustration of the ball-and-stick model with an antenna-shaped structure, structurally similar to chlorophyll. That's all I remember, would check any suggestions.--93.174.25.12 (talk) 09:52, 1 June 2016 (UTC)


 * The nature of crystals and polymers is that they can add "more of the same" monomer, virtually without limit.  Could it have been one of those ? StuRat (talk) 14:36, 1 June 2016 (UTC)


 * Proteins have a unique and very large structure (though there are more errors (or variations - we can't really say for sure the biology doesn't want the variation) in individual proteins than people sometimes imagine). A generation of heroic chemists in the early 1900s struggled to produce an accurate empirical formula for albumin ... you have to respect those guys, even though they had no idea what they were headed into. Wnt (talk) 00:30, 2 June 2016 (UTC)


 * So did they end up with "egg on their face" ? StuRat (talk) 13:10, 2 June 2016 (UTC)

Name of these aquatic plants
There is a particular type of small plant which grows on pond's surface. Their roots never reach the bottom of the pond. If people don't use the pond, then this plant leaves cover the entire surface like a green coat. From a distance it would look like there is no water. Most common types have small round leaves.

There is another type in Africa which don't cover the entire surface of ponds or lakes. But their leaves are very big in size and they have the shape of a large round plate. I saw that picture in National Geographic magazine. The picture was taken in 1903 in Africa. The children of a British officer were actually standing over those large flat leaves floating on the lake's surface. --Blade Ninja (talk) 11:53, 1 June 2016 (UTC)
 * The description in your first paragraph sounds like some sort of duckweed. As for the second paragraph, in most of the photos I've seen of children standing on aquatic plants' leaves, the plants have been the giant water lily, but that's native to South America, not Africa. Deor (talk) 12:48, 1 June 2016 (UTC)


 * Yep, lots of pictures here. Richerman    (talk) 17:42, 2 June 2016 (UTC)

What is the Knoop hardness of sugar?
Most data soucres for hardness either given minerals, metals, or construction materials (concrete, wood, etc.). Sucrose is none of those - can anyone find data on this? Tom pw (talk) 17:10, 1 June 2016 (UTC)


 * I imagine it would vary by type of sugar (sucrose, glucose, fructose, lactose, etc.), form (such as rock candy or a bag of sugar that's fused together), impurities (as in brown sugar), and water content, since sugars tend to be hydrophilic. StuRat (talk) 19:16, 1 June 2016 (UTC)
 * Hardness of sucrose crystals in Sugar technology reviews Jan 1986. Wikipedia has an article about the Knoop hardness test. Sucrose crystal hardness: A correlation with some parameters defining the growth kinetics uses the Vickers hardness test.AllBestFaith (talk) 19:20, 1 June 2016 (UTC)

other than interferon and ribavirin, what other medicines are used to increase immune response
knowledge should be discovered quickly in universeFAMASFREENODE (talk) 18:05, 1 June 2016 (UTC)
 * Several different types of Interferon which is a group of signaling proteins are now approved for use in humans to treat multiple sclerosis and some cancers, see the linked article. Ribavirin is an anti-viral drug used for severe RSV infection and hepatitis C infection, often in combination with an interferon. Taribavirin, a derivative of Ribavirin that is still under trial, has slightly better toxicological properties which may eventually cause it to replace ribavirin. AllBestFaith (talk) 19:07, 1 June 2016 (UTC)


 * Transfer factors have been used successfully. Whilst a hot bath may not be thought of today as a medical treatment, these were used too to increase the response;  just as fever does.--Aspro (talk) 20:43, 1 June 2016 (UTC)


 * Hmm, I'm thinking imiquimod - that article references two other TLR7 modifiers; I haven't looked recently to know how many it is up to total. Wnt (talk) 22:21, 4 June 2016 (UTC)

A puzzle of Stefano Ludovico Straneo
This is not a usual RD question, but rather a request for small help in research for an article.

For no particular reason, yesterday I wrote an article about Stefano Ludovico Straneo (1902-1997), a prolific Italian entomologist, who described over 1200 beetle species and published over 200 papers during a 60+ years long academic career. I scrapped it from only a few online sources, but upon investigation I got a little stuck. One would expect to find some more information about so active author, but all that I found is fragmentary and mostly puzzling. I would appreciate some help, mostly from Italian-speaking friends and/or those with a better access to academic sources. All my google-fu for those names failed so far, and I remain puzzled on details, so this request is a bit of stab in the dark. Hope I got someone's attention... No such user (talk) 21:17, 1 June 2016 (UTC)
 * Puzzle #1: Certain professor Stefano Ludovico Straneo has published 40+ works and textbooks from the fields of mechanics, industrial design and electronics:, also between 1941 and 1996. Is that the same person?! It's a bit unusual to be an expert in engineering and entomology simultaneously, but too many details suggest that he was, but I don't have any solid proof apart from the same name and period.
 * Puzzle #2: There is a detailed biography of Straneo the entymologist at, but only a snippet view is available. Those fragments suggest that his father was Paolo Straneo (1874-1968), a physicist and a friend of Einstein, but I have only clues. Does anyone have an access to the full book (damn, those are proceedings of a 1996 entomologist symposium, I guess those are hard to obtain), or any other proof that Paolo is Stefano's father? All my searches came up short. Paolo seems to have an entire university named after himself (http://www.straneo.gov.it/), but it does not seem to contain any detailed biography.


 * See http://www.segnaweb.it/index.php for Internet resources.—Wavelength (talk) 00:04, 2 June 2016 (UTC)

Bowel cleansing
Which is the most effective method of large bowel cleansing prior to colonoscopy: Picolax, Megalax ot enema??--178.106.227.250 (talk) 21:48, 1 June 2016 (UTC)
 * The one involving you reading the thing up at the top of the page about not giving medical advice. :) Whoop whoop pull up Bitching Betty &#124; Averted crashes 22:02, 1 June 2016 (UTC)
 * This appears to be a request for factual information not tied to any particular person, which is allowed. -- BenRG (talk) 23:58, 1 June 2016 (UTC)
 * Yes, see also Kainaw's criterion, which this question passes. SemanticMantis (talk) 14:18, 2 June 2016 (UTC)


 * Please ask your colonoscoper, we cannot answer this question. μηδείς (talk) 01:25, 2 June 2016 (UTC)


 * Here is a research article titled "Cleansing ability and Tolerance of Three Bowel Preparations for Colonoscopy" - it would seem to address your question. This article is also relevant, and addresses the importance of timing . This response contains references. It presents no treatment, prognosis, nor any advice of any sort. Any responses that give medical advice may be removed, possibly by me :) SemanticMantis (talk) 14:18, 2 June 2016 (UTC)


 * Saline is too hard on the kidneys. MgSO4 is the most gentle. Sleigh (talk) 14:55, 2 June 2016 (UTC)