Wikipedia:Reference desk/Archives/Science/2017 June 21

= June 21 =

Tendons and ligaments are classified under muscular or bone system?
Tendons and ligaments are classified under muscular system or bone system? Basically they are not bones or muscles and that's why I have doubt. 93.126.88.30 (talk) 02:17, 21 June 2017 (UTC)
 * Neither. They're connective tissue.  Rojomoke (talk) 06:30, 21 June 2017 (UTC)
 * Tissue type is a different kind of classification than the functionally-oriented ‘systemic‘ approach, though: each system comprises a variety of tissues, and some tissue types can be found in various different systems (connective tissue being pretty ubiquitous). Given the binary choice, I think tendons would belong to the muscular system, as they’re generally extensions of the fasciæ that wrap bundles of muscle fibres, while I’d assign ligaments to the skeletal system because they tie one bone to another, reinforcing or supporting the articulations.—Odysseus 1 4 7  9  19:50, 24 June 2017 (UTC)

Death = last thing seen gets imprinted in the eye
This sounds like a urban legend or fictional thing, but I guess it won't hurt to ask. Is it true that when a person dies, the last thing they see gets imprinted in the eye and the image can be retrieved somehow?

This was used as a plot point in Saint Seiya (manga only, the eye thing does not appear in the anime) by the character Black Swan.

(I tried to Google this, but keywords like "... image eye last thing seen death ..." got mostly pages about the completely unrelated notion that we see our whole lives past our eyes when we die.) --Daniel Carrero (talk) 07:32, 21 June 2017 (UTC)
 * Your hunch was right. The opsins in photoreceptor cells are degraded rapidly after being photoactivated by incoming light. This makes sense if you think about it. Your eye has to "refresh" in order to update what it's seeing. The membrane potential of the cell also rapidly resets to its resting state; furthermore, following death, the cell will deplete its energy reserves, the cell's ion pumps will stop working, and its membrane potential will dissipate. --47.138.161.183 (talk) 08:12, 21 June 2017 (UTC)


 * Wikipedia has an article on Optography.--Shantavira|feed me 08:16, 21 June 2017 (UTC)
 * An interesting read. The idea is not false after all. But its usefulness as a forensic tool is pretty near zero. It would be interesting to see if this Gary Larson item could be accurate. ←Baseball Bugs What's up, Doc? carrots→ 10:40, 21 June 2017 (UTC)
 * Almost all organic cells keep functioning for a while after an Organism is regarded dead. Else organ transplantation operations, from victims of accidents that subscribed to be donor in case of death, would not work. So this imprint theory is completely made up nonsense as usual in movies and shurely much more so in japaneese ones. --Kharon (talk) 07:00, 22 June 2017 (UTC)
 * The article disagrees. ←Baseball Bugs What's up, Doc? carrots→ 10:56, 22 June 2017 (UTC)


 * Optography is a smelly article. The whole scientific literature seems to boil down to Wilhelm Kühne; a GScholar search for "optography" returns a whopping 35 results, most of them false positives, and zero of them are recent research purporting that to be true (this, assuming it went through a relatively thorough search of the available literature, is certainly discouraging). I am going to put this on the fringe theory noticeboard. Tigraan Click here to contact me 11:22, 22 June 2017 (UTC)
 * The article Optography is already categorized in Category:Pseudoscience. So its hardly allowed to cite this here in Reference desk/Science ;D. --Kharon (talk) 17:28, 22 June 2017 (UTC)
 * But we don't have Reference desk/Pseudoscience! Plus, if the answer were "Yes, this is true. Eyes do work like that in real life." it would be science. (thanks for the answers!) --Daniel Carrero (talk) 19:43, 22 June 2017 (UTC)

Dicotyledonous wood
What on earth is dicotyledonous wood? I came across the term while researching for draft:Akal Wood Fossil Park. There's no WP article about it and Google search mostly yields research papers only which are largely unintelligible to lay readers. A book search also failed to turn up any explanation for what it is. 223.227.109.162 (talk) 13:53, 21 June 2017 (UTC)
 * Obviously it's wood from a dicot, rather than a monocot. However, is it a term in any sort of use?
 * I checked my usual source for all such, R. Bruce Hoadley's Understanding Wood. It's not in there. A thorough check might also cover the US Forest Products Handbook. So although woodworkers are deeply interested in wood structure and distinguish between species, let alone hardwood and softwood, there's no evident distinction for dicots and monocots. Timber species are almost all dicots, the only monocots I can think of for commercial timber production would be the woody palms and bamboo.
 * From the context, I think that this is a palaeontological question, not a timber question. The point is that monocots are seen as "early" plant in a geological context and the dicots as "later". Their fossils are also identifiable by species, thus then (indirectly) categorizable as either dicot or monocot.
 * AFAIK (I may be wrong here, I'm no botanist, just a carpenter), there is no specific timber or fossil structure that shouts out "dicot", any more than other differences between species (there are some common differences between softwood and hardwood as groups). So a botanist still has to identify down to a finer detail than "monocot", such as "a palm" or "a bamboo" before identifying to the group level. But if the distinction is interesting as a fossil one, then they might be doing just that. Certainly identifying fossil species from structure, seeds or pollen grains is an important discipline. Andy Dingley (talk) 14:34, 21 June 2017 (UTC)
 * I think, most xylologists and foresters and botanists would not consider e.g. bamboo to be be true wood anyway. While our article doesn't call normal wood, dicotyledonous wood, it does have section on monocot wood, indicating its sort-of-wood status. So I suspect dicotyledonous wood is being used here as sort of equivalent to "true wood", and this is useful verbiage (Edit,see below) to distinguish from monocot fossils that may also be woody. SemanticMantis (talk) 16:56, 21 June 2017 (UTC)
 * And to clarify further: " there is no specific timber or fossil structure that shouts out "dicot", any more than other differences between species ", I don't think that's true. I think if a paleontologist had a small bit of bamboo fossil and a small bit of coinfer dicot fossil, they could immediately distinguish the two. The growth of monocot "wood" is very different, they don't have the same tissue structures. See here for some discussion of differences, and e.g. here . One easy detail is that monocots won't have growth rings. SemanticMantis (talk) 17:22, 21 June 2017 (UTC)


 * Monocots (for the most part) don't produce wood. Nor are monocots the most primitive angiosperms, the claim above is not even close.  The Magnoliids are usually called dicots, and they along with a few other minor groups are the oldest angiosperm clades.  They produce wood, unless they are herbaceous.  The two crown clades of Angiosperms are the monocots and the Eudicots which are equally recent.  Conifers also produce wood, so it is not unique to Angiosperms.


 * Basically, dicot wood in the broad sense is what we think of as hardwood, and include wood from the Magnoliids and the Eudicots, but excludes wood from the conifers and monocots. It's a taxonomically invalid (polyphyletic--like calling whales fish) grouping, but it is useful in forestry and woodworking.


 * Of course there are the articles wood and secondary growth. There's also Plant Biology, Raven, Evert, and Eichorn which gives an encyclopedic view of the biology of the Plantae proper as well as other organisms such as fungi and protists historically treated as part of botany from an evolutionary and physiological standpoint.


 * μηδείς (talk) 01:46, 22 June 2017 (UTC)
 * Nobody said monocots were primitive, so I'm not sure what or whose claim you're referring to. But I do think you're right that coniferous wood would be excluded from "dicot wood", so I've stricken the "true wood" bit above, because it's confusing. For the rare occurrence where it comes up, "dicot wood" is basically synonymous with "hardwood" SemanticMantis (talk) 15:02, 22 June 2017 (UTC)
 * "From the context, I think that this is a palaeontological question, not a timber question. The point is that monocots are seen as "early" plant in a geological context and the dicots as "later"."
 * could be intepreted that way, whether or not it was the intention. I personally did intepret it that way. Nil Einne (talk) 16:33, 22 June 2017 (UTC)


 * "*Monocots (for the most part) don't produce wood" but see Coconut timber. Alansplodge (talk) 09:53, 23 June 2017 (UTC)
 * That's why it's called timber. True wood is a form of secondary growth, where new layers grow over old ones yearly from secondary meristem.  Monocots do not increase in girth this way, having lost the ability, hence coconut timber is a granular pithy material, not true wood.  Functionally it can replace wood, and has some excellent qualities, as can bamboo.  But biologically neither is true wood, with annual rings, as found in the gymnosperms, magnoliids, and eudicots. μηδείς (talk) 18:22, 23 June 2017 (UTC)

Solar eclipse hype
Today on the CBS Morning News Charlie Rose said "A total solar eclipse will cross the United States for the first time in 99 years." That would at first blush seem to mean no "total eclipse" in any US state since about August 1918. I have seen this August 2017 eclipse similarly hyped elsewhere. It seems like every decade the newscasters tell us there is about to be the first such eclipse in umpty-ump years and there won't be another one in our lifetimes, as if we have no memory of previous eclipses. The article List of solar eclipses visible from the United States lists "total eclipses" which crosses the US.Neglecting annular and partial eclipses, it lists the most recent one as the Solar eclipse of July 11, 1991 and says Hawaii (by then long since a US state) saw a total eclipse. It lists Solar eclipse of February 26, 1979 whose article says there was a total eclipse in five US states. It lists Solar eclipse of March 7, 1970, whose article's map appears to show totality across several east coast states. It lists Solar eclipse of July 20, 1963 whose map appears to show totality crossing at least Maine. It includes the Solar eclipse of June 30, 1954 which had totality over several northwest states. It says about the Solar eclipse of July 9, 1945 that "The path of totality crossed northern North America, ..." and a semi-legible map shows the path crossing several northwest US states. It says the Solar eclipse of August 31, 1932 hit the NE US and the map seems to show a couple of NE states in the path. The Solar eclipse of April 28, 1930 hit the northwest US states. The Solar eclipse of January 24, 1925 produced a total eclipse viewable in New York City. The list claims the Solar eclipse of September 10, 1923 hit the SW US, but the fuzzy map and the article about the eclipse imply the totality missed the US. Then we get to the 99 year eclipse: The Solar eclipse of June 8, 1918, which crossed many states from the northwest to the southeast. But how can they dismiss the eclipses of 1991, 1979,1970, 1963, 1954, 1945, 1932, 1930, and 1925? From 1918 to 2017 inclusive, there have apparently been 11 total eclipses visible in one or more US states, for an average of 8.9 years. What am I missing here? That is more often than some people trade cars. Do astronomers endorse this hype? Edison (talk) 14:25, 21 June 2017 (UTC)
 * The 1925 eclipse was pretty cool. A scientist asked people what street they were on and whether they saw totality and 100% saw it above 96th Street and 0% saw it below 94th Street (or something similar). 1 street is only 264 feet. Sagittarian Milky Way (talk) 21:06, 21 June 2017 (UTC)
 * One news story added the qualifiers "first total solar eclipse to cross the United States from coast to coast in nearly a hundred years" which seems accurate, but so far as one's personal experience, you just see it in one place (absent pacing it from inside a Concorde as was once done)., and the sense of wonder is not much greater to know that many others can see it too.  Yet Rose said he had "never seen one, and little wonder, since there hasn't been one in a hundred years" which seems to be nonsense. Edison (talk) 14:48, 21 June 2017 (UTC)
 * Correct, that's the big thing here. coast to coast, more states, more 'potential observers within reasonable travel distance' than in a long while. 1918 was somewhat comparable to this event in terms of the track. So 'for the first time in 100 years' is somewhat accurate in that regard, but it should be noted that the 2045 event will be similar (longer even). So yeah, it's a bit of hyperbole, but then, that's the news. For anyone outside Hawaii, NYC, or the North West, there is a big chance that you have not had this good an option to observe a full eclipse in your lifetime before. Esp. because modern times has made travel this cheap. —Th e DJ (talk • contribs) 15:17, 21 June 2017 (UTC)
 * It's ignorance, more than anything else.  Here's a report of an eclipse which never happened: 79.73.134.123 (talk) 15:23, 21 June 2017 (UTC)
 * BTW, as having personally observed a total eclipse in France when I was in my teens, I would advise any and everyone to take any opportunity you can to observe it. It's one of the strangest experiences I ever had. Will never forget it. —Th e DJ (talk • contribs) 15:28, 21 June 2017 (UTC)
 * Solar eclipse of February 15, 1961.  I remember it as a deep partial eclipse.   My mother saw a total one - for practically everyone in Britain 11 August 1999 was clouded out, and the one before that was 30 June 1954 (also visible as total in the United States).   Our article Solar eclipse of August 11, 1999 could do with some work - it claims it was "the first visible in the United Kingdom since 29 June 1927". 79.73.134.123 (talk) 16:11, 21 June 2017 (UTC)
 * Few saw the '91 umbra in America because the average July sunniness of Baja vs Hawaii made many people plan to fly or drive to the tip of the Baja desert to see it and by the time the weather report showed it was more likely to be seen in Hawaii than Mexico flights to Hawaii were probably pretty expensive. In the end the desert of Baja California had lots of cloud and the tropical rainforest of Hawaii saw the eclipse. Sagittarian Milky Way (talk) 16:17, 21 June 2017 (UTC)

What plane is this
What plane is this? I've never seen anything with that kind of a belly before. The screenshot is from 0:40 of this video. Scala Cats (talk) 20:45, 21 June 2017 (UTC)


 * C17 Globemaster? Someguy1221 (talk) 21:11, 21 June 2017 (UTC)


 * That's it. Thanks! Scala Cats (talk) 21:32, 21 June 2017 (UTC)

Can acetic acid in aqueous solution alone pickle foods?
Is it safe enough to be consumed? 50.4.236.254 (talk) 22:51, 21 June 2017 (UTC)
 * Yes, if suitably manufactured. In the UK it has long been sold as "Non-brewed condiment", diluted and coloured with caramel, as a substitute for malt vinegar. "Vinegar", if sold under that name, must be made by brewing (or at least fermentation). NBC uses industrial acetic acid. It is cheapest (if you're buying acetic acid for industrial workshop use) to buy these "acetic acid pickling vinegars" in gallon jars, rather than a chemical reagent-grade acid.
 * Note though that glacial acetic acid is fairly easily available but warrants all the care in handling of any concentrated acid. Andy Dingley (talk) 23:03, 21 June 2017 (UTC)
 * This sounds like normal "white vinegar" we use in the U.S. It is the most common vinegar and apparently can use either foodstuffs or petroleum as a starting material although the industry claims not to be aware of any company making food-grade vinegar from petroleum. It seems in the UK, malt vinegar may be the main type in use and laws do not allow certain other products to be labeled as vinegar: non-brewed condiment. Rmhermen (talk) 17:24, 22 June 2017 (UTC)
 * Yes, and you could pickle with it, but it would be a bit nasty if used "alone" (emphasis in title). A typical pickling solution would include salt and other seasonings. Matt Deres (talk) 20:08, 22 June 2017 (UTC)