Wikipedia:Reference desk/Archives/Science/2017 February 13

= February 13 =

Lack of certain vitamines and\or minerals can make someone more appetative for eating ?
I know that people who lack Zinc tend to have less appetite. On the contrary, Did a vitamin or mineral that lacking it makes humans to be with more appetite ever found in the seemingly-objective scientific research? 77.180.51.125 (talk) 09:11, 13 February 2017 (UTC)


 * I wonder if there's anything in Pica that will help with this? --TammyMoet (talk) 14:45, 13 February 2017 (UTC)


 * See specific appetite. StuRat (talk) 14:50, 13 February 2017 (UTC)

What is the relationship between obesity and metabolic disorders?
1) Does being overweight cause metabolic diseases?

2) Does having a metabolic disease predispose the body to become overweight?

3) Or is there a confounding variable or are there many confounding variables?

4) Also, is it possible that a specific type of unbalanced diet cause obesity even if the number of calories is relatively low?

5) Socially, do malnourished, extremely thin people receive more sympathy than malnourished, overweight people? 107.77.194.85 (talk) 15:48, 13 February 2017 (UTC)


 * I numbered your Q's for those who wish to respond to specific ones.


 * For 1 and 2, see metabolic syndrome.


 * For 3, yes, it's quite confusing. For example, when trying to lose weight, you need to avoid triggering the starvation response.  Genetics definitely play a role, too.


 * For 4, not exactly. If you have a very low calorie diet, even if unhealthy, the average person should not become obese.  However, it would be extremely difficult to keep your calories low on such a diet, as the lack of nutrients will make you constantly hungry.  Also, eating extreme amounts of sodium may cause you to "gain weight" by retaining water and foods which cause constipation may cause weight gain from retained feces.  Those aren't actually obesity but could be mistaken for it.


 * For 5, sure, it's easier to see anorexia as a mental disease and being overweight as just a lack of control, probably because the average person gains weight when they stop worrying about what they eat, while losing weight seems like it requires an extreme effort. And for those people who are underweight because there is no food for them to eat, or they are physically sick, sympathy is even more common.  An exception might be for fat toddlers, where clearly they are not to blame, it's either the parents or a medical problem.   StuRat (talk) 15:53, 13 February 2017 (UTC)

Are the viruses infections is forever in the body after the enter?
I've seen the lecture (#1) of Prof. Vincent Racaniello from Columbia University on Youtube that says about the viruses infection "once infected it is for life" (see here 7:55). Does it says that a virus which already entered somebody, cannot be removable and it's there for all of the period of life? 93.126.88.30 (talk) 19:24, 13 February 2017 (UTC)


 * The major problem with the immune response to viruses is that they are internal parasites of cells. Antibodies and the cells that mediate the immune response have to react to either the cell surface, or to the debris of a cell destroyed by apoptosis or necrosis.  If the virus is dormant inside a living cell, and not producing recognizable antigens, then it is camouflaged from the immune system, and hence "once infected it is for life".  Retroviruses go even one step deeper.  They not only infect the cell's cytoplasm, they get themselves inserted into the cell's own DNA, inside the nucleus, an even deeper level of attack.


 * Bacteria, on the other hand, often live outside the cell. They are easier to find (I am generalizing and simplifying) and they also have special metabolic needs and pathways for reproduction, and are hence susceptible to antibiotics, while viruses may or may not be susceptible to antivirals, and antivirals tend to be less selective, often being toxic to the patient as well.  This is why the best attack against viruses is prevention through immunization when possible.  After you have been infected, successful treatment is very difficult.  See Hepatitis C for a type of virus which can be "cured" after infection.


 * See also Shingles, which result from an earlier chicken pox infection. The Zoster virus lies dormant in nerve cells until the patient loses effective immunity due to age or immunosuppression.  The shingles vaccine works by getting the body primed to react to the virus if and when it resurfaces.


 * In any case, being "infected forever" does not always mean having active disease. μηδείς (talk) 20:36, 13 February 2017 (UTC)


 * It probably depends on which cells they infect, as some cells, like red blood cells, are replaced quite often, so a virus which solely infects them would need to be somewhat active to spread to other blood cells before the cells they are in are all destroyed and replaced. Nerve cells, on the other hand, may last your entire life, so a virus could remain dormant in those for decades. StuRat (talk) 21:13, 13 February 2017 (UTC)


 * To be clear, mature red blood cells do not have nuclei, and cannot be infected by viruses. Someguy1221 (talk) 21:17, 13 February 2017 (UTC)


 * It is only true of mammals that their red blood cells are anucleate. In other vertebrates they do have nuclei: see our article Nucleated red blood cell. Jmchutchinson (talk) 07:34, 14 February 2017 (UTC)


 * I viewed the relevant portion of the video, and I believe in context he's talking about the specific viruses he's named, which are listed on the same slide. These viruses are the herpesviruses, and it's true that those viruses produce latent infection. I don't believe all viruses do, though. Some, like influenza, just reproduce inside an infected cell and then destroy it to release the new viruses. See lytic cycle and lysogenic cycle. This is why you can develop shingles decades after infection with varicella, but you don't randomly re-develop the flu. --47.138.163.230 (talk) 06:57, 14 February 2017 (UTC)

What does the letter O in blood type O stands for?
93.126.88.30 (talk) 19:44, 13 February 2017 (UTC)


 * Type O blood: "Landsteiner originally described the O blood type as type "C", and in parts of Europe it is rendered as "0" (zero), signifying the lack of A or B antigen." So it seems it doesn't stand for anything directly, though it may be related to a zero, or a lack. SemanticMantis (talk) 19:55, 13 February 2017 (UTC)
 * Or Ordinary, being that it's the most common. Akld guy (talk) 20:08, 13 February 2017 (UTC)
 * Most common depends on where you look. E.g. O is not most common in Norway, see Blood_type_distribution_by_country. Also, do you have any sources for O standing for "ordinary"? I don't see that mentioned in our main article. SemanticMantis (talk) 20:17, 13 February 2017 (UTC)


 * Throughout the world, type O is by far the most common. I didn't need to supply a source because you had already speculated that it might stand for zero or 'lack', so I was merely adding to the list of possible abbreviations. Akld guy (talk) 23:44, 13 February 2017 (UTC)
 * Except that its standing for zero is not "speculation". ←Baseball Bugs What's up, Doc? carrots→ 01:15, 14 February 2017 (UTC)
 * As for "oh" vs. "zero", "oh" is often used to mean "zero". If someone is batting .305, it will typically be read out loud as "three-oh-five", or a count of 0 balls and 2 strikes, for example, is typically said "oh and two". Even my modern telephone has "zero" standing for both the number zero and "Operator". ←Baseball Bugs What's up, Doc? carrots→ 01:19, 14 February 2017 (UTC)
 * I bet you told your grandma how to suck eggs too. Akld guy (talk) 02:01, 14 February 2017 (UTC)
 * I have no idea what that means. ←Baseball Bugs What's up, Doc? carrots→ 02:30, 14 February 2017 (UTC)
 * Teaching grandmother to suck eggs. And you tout yourself as a person familiar with the English language?? Akld guy (talk) 04:06, 14 February 2017 (UTC)
 * That's a hick expression I'd never heard until now. And I don't tout myself as an expert on anything. I'm merely a native speaker. ←Baseball Bugs What's up, Doc? carrots→ 11:12, 14 February 2017 (UTC)
 * Don't dismiss it as a hick expression. It's still a very well known saying that happens to have almost fallen into disuse among the younger set. Akld guy (talk) 11:43, 14 February 2017 (UTC)
 * Obviously Bugs has never read The Hobbit, whose author is reputed to have known something about the English language. {The poster formerly known as 87.81.230.195} 90.203.118.169 (talk) 15:59, 14 February 2017 (UTC)
 * No, I've never read any of the Tolkien stuff. ←Baseball Bugs What's up, Doc? carrots→ 16:21, 14 February 2017 (UTC)
 * The expression teaching grandmother to suck eggs is a stupid expression. Tolkien was a writer and this is a reference desk. We are not engaged in creative writing. Bus stop (talk) 16:13, 14 February 2017 (UTC)


 * EO concurs that the O was originally "zero". ←Baseball Bugs What's up, Doc? carrots→ 21:50, 13 February 2017 (UTC)
 * You can find lots of references that say O, and lots that say 0. You can find refs that say "O" stands for "Ohne", and refs that say it never did.  It's a complicated history; the original was "C", and all parties who were involved in the original dispute between "O" and "0" concur that it is proper to use the letter O for the blood group and not 0 or NULL. .  Not that that will lead the countries where the number 0 is used to change. - Nunh-huh 10:51, 15 February 2017 (UTC)

Proportional or Gravitational Constant “G”
Two masses are the requirement of newton's gravitational force in F= GMm/r^2 equation. Since gravitational constant “G” requires two masses in the equation of G = Fr^2/ Mm, therefore is it possible for “G = 6.67408 × 10-11 m3 kg-1 s-2” to exist if we have only a single mass in the whole universe?

No second or falling mass m means no force and hence no gravitational constant G but G appears in the equation of gravitational acceleration of gravitating mass M = GM/r^2 – is it possible?

Einstein says gravity is a not a force at all but the curvature of space-time, therefore according to dimensional analysis G seems to be depended upon density (unit of G = inverse unit of the density of time) – is this true if not why? 2001:56A:7399:1200:2998:3DF5:B730:21E8 (talk) 20:23, 13 February 2017 (UTC)EEK


 * It also depends on how you define a "thing". This is not trivial.  Objects as large as galaxies exert gravitational attraction on each other (see, for example, galaxy cluster) and yet a galaxy is so diffuse you can go many light years between any substantially dense objects, from a human perspective.  The only way to have a "one mass" universe is if your single particle is a fundamental particle, and even that may or may not be composed of simpler particles.  There are serious theories in Physics which presume it's turtles all the way down, and there are no truly fundamental particles.  So, your question of a "single mass universe" is not so simple as it just isn't that easy to draw a line between "one single mass" and "a bunch of individual masses close together".  -- Jayron 32 20:40, 13 February 2017 (UTC)


 * I would also note that G the gravitational constant exists whether or not anything exists for which it matters, although at that point it's meaningless. Pi exists even if no one uses math. Someguy1221 (talk) 22:04, 13 February 2017 (UTC)


 * That's an interesting philosophical Q. After all, we could come up with an infinite number of laws describing how various forms of nonexistent exotic matter behave, couldn't we ? StuRat (talk) 22:15, 13 February 2017 (UTC)


 * Philosophy aside, it is impossible for a non-pointlike universe to contain only a single mass. If our present-day understanding of physics is correct, there is a nonzero energy (and therefore mass) associated with null-oscillations of various fields; and therefore any volume of what we think of as a "vacuum" still has some mass. It is not presently known, however, what this mass is. Please see Zero-point_energy and Cosmological constant problem, respectively. Dr Dima (talk) 01:18, 14 February 2017 (UTC)

Hooke and the monk's room
I was clicking around and noticed something curious: some of our articles about cells claim that Hooke chose the name because he thought that what he was observing looked like monks' cells (generally sourced by throwaway lines from bio textbooks), and some of them claim that he chose the name because he thought they resembled the cells in a honeycomb. A quick look at an online copy of Micrographia shows that, first, he never says anything about monks in it, and second, he does talk about the sexangular cells of the honeycomb before going on to say "these pores, or cells...". Has anyone ever investigated the origin of the monk story? Is there some letter somewhere where he says "hey these things are a lot like a monk's room", or was it made up from whole cloth in the year X by author Y? -165.234.252.11 (talk) 20:52, 13 February 2017 (UTC)
 * Robert Hooke first observed cells in 1665 on a thin slice of cork under a simple microscope. The Online Etymology Dictionary notes only that cell was used in 14c., figuratively, of brain "compartments;" used in biology by 17c. of various cavities (wood structure, segments of fruit, bee combs), gradually focusing to the modern sense of "basic structure of living organisms" (which OED dates to 1845). The source for Hooke's thinking of monks' cells is Achiever's Biology (1990) by Alan Chong Tero. Blooteuth (talk) 00:17, 14 February 2017 (UTC)
 * The OED has a cites from hundreds of years earlier (1395): "Such wonyng places [sc. of bees] and celles ben alle sexe cornered"; then from 1425: "Also, swete Ihesu, þi bodi is lyke to an hony combe, ffor it is eche way fulle of cellis, and eche celle fulle of hony", and a couple more for honeycomb cells before Hooke's usage. Hooke was probably the first to use it of cork, but the OED comments: "Although Robert Hooke, Nehemiah Grew and other writers used the word for microscopic cavities found in plant tissues, the modern understanding of the cell is usually taken to begin in the early 19th cent. with the work of J. B. Purkinje and other (mainly French and German) botanists and anatomists, and is particularly associated with M. J. Schleiden (in plants) ( Arch. f. Anat., Physiol. u. wissensch. Med. (1838) 137) and T. Schwann (in animals) ( Mikroskop. Untersuchungen (1839))."   D b f i r s   16:44, 14 February 2017 (UTC)
 * I found the original here.   Yes, it's just somebody long before the invention of the microscope saying that Jesus' body is made up of cells.  Mystics... always just enough inexplicable insight to make you wonder, never enough to prove anything to a skeptic. ;) Wnt (talk) 00:49, 15 February 2017 (UTC)
 * Interesting stuff, thanks everyone! do you mean that Achiever's Biology is the first instance of the monk story? Is there a source that talks about it being the origin? -165.234.252.11 (talk) 17:44, 15 February 2017 (UTC)
 * The source Achiever's Biology (1990) by Alan Chong Tero is cited in the article Cell (biology) that I cited. Also cited is Cell and Molecular Biology: Concepts and Experiments (2009) by Gerald Karp who writes "Hooke called the pores cells because they reminded him of the cells inhabited by monks living in a monastery". Clearly these are modern sources. I have nothing earlier. Blooteuth (talk) 22:26, 15 February 2017 (UTC)
 * Well, I seriously appreciate that you take the time to answer ref desk questions with sources instead of long-winded anecdotes and wild speculation, but you're just retracing the steps that led me here. One article says one thing (citing throwaway lines in textbooks), other articles say another thing (citing the man himself), where should I even start looking if I want to find the origin of the textbook story? -165.234.252.11 (talk) 19:12, 17 February 2017 (UTC)