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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)[reply]

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

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

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)[reply]

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)[reply]

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)[reply]

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)[reply]

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)[reply]

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)[reply]

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)[reply]

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)[reply]

What does the letter O in blood type O stands for?

93.126.88.30 (talk) 19:44, 13 February 2017 (UTC)[reply]

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)[reply]

Or Ordinary, being that it's the most common. Akld guy (talk) 20:08, 13 February 2017 (UTC)[reply]

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)[reply]

Zero-sum discussion

The following discussion has been closed. Please do not modify it.

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)[reply]

Except that its standing for zero is not "speculation". ←Baseball Bugs ^{What's up, Doc?} carrots→ 01:15, 14 February 2017 (UTC)[reply]

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)[reply]

I bet you told your grandma how to suck eggs too. Akld guy (talk) 02:01, 14 February 2017 (UTC)[reply]

I have no idea what that means. ←Baseball Bugs ^{What's up, Doc?} carrots→ 02:30, 14 February 2017 (UTC)[reply]

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)[reply]

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)[reply]

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)[reply]

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)[reply]

No, I've never read any of the Tolkien stuff. ←Baseball Bugs ^{What's up, Doc?} carrots→ 16:21, 14 February 2017 (UTC)[reply]

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)[reply]

EO concurs that the O was originally "zero".[1] ←Baseball Bugs ^{What's up, Doc?} carrots→ 21:50, 13 February 2017 (UTC)[reply]

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. [2]. Not that that will lead the countries where the number 0 is used to change. - Nunh-huh 10:51, 15 February 2017 (UTC)[reply]

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[reply]

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)[reply]

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)[reply]

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)[reply]

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)[reply]

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)[reply]

Robert Hooke first observed cells in 1665 on a thin slice of cork under a simple microscope. The Online Etymology Dictionary notes[3] 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)[reply]

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))." Dbfirs 16:44, 14 February 2017 (UTC)[reply]

I found the original here. [4] 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)[reply]

Interesting stuff, thanks everyone! @Blooteuth: 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)[reply]

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)[reply]

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)[reply]

February 14

How could the universe be infinite?

Apparently the universe could be finite or infinite. I'm curious how it could be infinite given the universe has an age and finite speed of expansion? — Preceding unsigned comment added by 2.102.184.32 (talk) 03:23, 14 February 2017 (UTC)[reply]

Simple. It was always infinite <added>at any positive time after the Big Bang</added>. In an infinite universe, the Big Bang was ~~not~~ a moment of zero size, ~~but rather~~ <added>and also</added> of infinite (or maximum) density. We have some discussion of this at size of the universe and shape of the universe. Someguy1221 (talk) 03:29, 14 February 2017 (UTC)[reply]

So the Universe at the time of the Big Bang was just a tiny area, but in that tiny area there was an infinite density of stuff, and when it exploded the infinite stuff expanded to an infinite area?— Preceding unsigned comment added by 2.102.184.32 (talk • contribs)

<added>Yes</added>~~Not quite. The theory would go that at the time of the Big Bang, the universe was infinite in both density and extent. It never went from finite to infinite~~. You might ask how something infinite can get bigger... well, it can. In the case of the universe, an expanding and infinite universe is merely one in which though the total size is always "infinity", the bits inside are getting further apart from one another at all times. Someguy1221 (talk) 04:42, 14 February 2017 (UTC)[reply]

It's not clear that it's meaningful to talk about the exact moment of the Big Bang. Cosmologists can tell all sorts of things about what happened 100,000 years after the Big Bang, or 1 second after it, or 10⁻³⁵ seconds after it, but you'll basically never see them say anything about exactly 0 seconds.

That said, it's possible to make sense, at least mathematically, of the universe having infinite extent at any positive time after the Big Bang, but zero extent at the exact moment of the Big Bang. I'll elaborate below. --Trovatore (talk) 04:46, 14 February 2017 (UTC)[reply]

You know what, Trovatore, I think you have to be right, and I have to be wrong. Thanks for throwing me the "any positive time after the big bang" life raft :) Someguy1221 (talk) 05:03, 14 February 2017 (UTC)[reply]

(edit conflict)Just a bit more on how something infinite can get bigger, a lot of people have trouble thinking about infinity as mathematicians do. Take an example. There are infinity numbers between 0 and 1, because you can write nonrepeating decimal expansions forever. There are also infinity numbers between 0 and 10. Are there more numbers between 0 and 10, than between 0 and 1? All numbers between 0 and 1, are also between 0 and 10. But the interval from 0 to 10 also has numbers that aren't between 0 and 1. So you'd like to say that there are more numbers in the larger span. But it's definitely true that both spans contain infinity numbers. If you accept that this is logical, then you may also accept that a universe that was always infinite in size can get bigger, defined as the average space between particles at least. Someguy1221 (talk) 04:48, 14 February 2017 (UTC)[reply]

(edit conflict) Wikipedia has an article titled shape of the universe which discusses some of the geometric possibilities that could produce an infinite universe. You aren't the first person to wrestle with such issues; see Olbers' paradox for one such famous issue with infinity. --Jayron 32 03:31, 14 February 2017 (UTC)[reply]

Actually its all still unknown. The Big Bang is an widely agreed assumption, not a proven fact! The universe may be much older or maybe it was always here. Neither the "age of the universe" nor "its rate of expansion" are really "given" facts in scientific sense, so your basic assumption is already wrong. Both are infact also "just" widely agreed on assumptions aswell. Astrophysics still has allot of homework to do on what has been discovered by astronomy and astronomy is barley started. Remember Hubble Space Telescope is just 26 years young and it is a very restricted instrument, atleast compared to the new James Webb Space Telescope, that will start collecting new facts in 2 years.

Likely there are some groundbraking discoveries about to be made in the near future and it will not be the first time big theories get dumped into history books as nice try but proven to be wrong if they find stuff that doesnt add up. --Kharon (talk) 04:25, 14 February 2017 (UTC)[reply]

Saying the Big Bang is "not a proven fact" is disingenuous. It is enormously well-supported by evidence. Scientific theories, especially well-tested theories like the Big Bang, aren't just guesses. (I'm reminded of the frequent creationist canard that "evolution is only a theory!") It's true that theories are adjusted to account for new evidence, but that doesn't mean learning anything new requires us to throw them out and start over from scratch. As Lawrence Krauss is quoted as stating in our Big Bang article, "[The] big bang picture is too firmly grounded in data from every area to be proved invalid in its general features." --47.138.163.230 (talk) 06:45, 14 February 2017 (UTC)[reply]

To concur with 47.138, it should be noted that you are not a proven fact. However, the Big Bang is as well accepted as anything else, so there's no need to say that it "isn't a proven fact". If you demanded more proof for the Big Bang than currently exists, then you probably don't believe anything has ever been proven ever. --Jayron 32 12:01, 14 February 2017 (UTC)[reply]

But the February 2017 Scientific American has an article by 3 astrophysicists, 2 from Princeton and 1 from Harvard, saying that in their opinion the latest data strongly refutes the Big Bang, and they favor a Big Bounce from a previously contracting universe as an alternative theory consistent with the data. Loraof (talk) 17:36, 14 February 2017 (UTC)[reply]

We have an article on the Big Bounce theory. It's actually conceptually very similar to the Big Bang, in that ~13.7 billion years ago the universe was contracted into an immensely dense, tiny volume. They differ fundamentally in that Big Bounce posits a "before". Big Bounce could be true, possibly while keeping true most of the Big Bang theory. Someguy1221 (talk) 01:16, 15 February 2017 (UTC)[reply]

Per Someguy1221, the story is clearly "Some scientists have proposed refining current theories about the origin of the universe" and not "SCIENTISTS NOW SAY EVERYTHING YOU KNOW IS WRONG!" Science works this way by small incremental changes to established theories. Complete rejection of established, well-supported theories are exceedingly rare, instead most of the major work is in refinement. The popular press (and/or the Intelligent Design crowd) latch on to these refinements and blow them way out of proportion to say "SCIENCE SAYS X IS WRONG" or "SCIENTISTS DON'T KNOW WHAT THEY ARE DOING" when, in reality, these sorts of tweaks and changes to theories happen continuously, and don't prove that older scientific theories were wrong, just that we get better results with more accumulated knowledge. --Jayron 32 13:16, 15 February 2017 (UTC)[reply]

Here's a silly toy example that is absolutely not a picture of the actual universe, but might give some insight into how such a thing could be logically possible.

Suppose the universe is laid out on a standard 3-dimensional Cartesian coordinate system, where at any fixed comoving time, every point has a set of coordinates (x, y, z) for some real numbers x, y, z.

Now suppose that all particles go exactly with the Hubble flow, and that each particle has three coordinates x₀, y₀, z₀ that tell you where it is at one second after the Big Bang.

Suppose further that, at any time t seconds after the Big Bang, said particle is at position (tx₀, ty₀, tz₀).

Then you can easily check that, at any positive time t, there are particles arbitrarily far apart from one another.

However, at the exact moment of the Big Bang, namely t=0, all particles are at location (0, 0, 0). --Trovatore (talk) 04:54, 14 February 2017 (UTC)[reply]

I found your toy example extremely useful. I got it wrong above at first, but I found your argument excellent when thinking of the problem backwards. Instead of asking what happens after the Big Bang, asking what happens starting from the present and working back. Now of course if the universe is finite in size, you can compress it as much as you want, and it won't reach infinite density as long as its volume is non zero. Well, if you start with an infinite universe, it's actually still really hard to get infinite density. As long as there is space between particles (assumed to be points), you can keep compressing forever. You can get any two particles, arbitrarily far apart in the universe, to be arbitrarily close, without ever hitting infinite density. In this thought experiment, you don't reach infinite density unless every particle is touching every other particle. Now this started with an infinite extent, infinite mass, finite density universe. If we work forward from my initial (and now I think wrong) assumption of a universe with infinite extent, mass and density, I'm not sure you ever get a universe that is not all of the above. I won't drone on about a counterfactual, but I don't think logic (let alone physics) even works. So thanks again. Someguy1221 (talk) 05:18, 14 February 2017 (UTC)[reply]

Suggested videos from PBS Space Time: [5] [6] [7] --47.138.163.230 (talk) 06:45, 14 February 2017 (UTC)[reply]

I suspect the toy example leads astray. The molecules are not expanding neatly at kx, ky, kz. They are moving all over the place, smashing against each other. A second after the Big Bang every molecule was colliding with some unimaginable number of other molecules, so in that "short" amount of time, a whole lot of stuff was going on. I don't know if simply taking ln t = "tau" is really an accurate way to look at it, but I think we can put an infinite amount of history into a finite amount of time - under regimes of physics that used ever smaller Compton radii for ever larger masses for particles stable on ever smaller time scales the further back you look. Eventually they get down the Planck radius, particles that are black holes, nobody knows what happens - but this is not a guarantee that physics before that point was boring or nonexistent ... it gives quite a hint to the contrary. Wnt (talk) 17:52, 14 February 2017 (UTC)[reply]

Well, it was an example with a very limited purpose, to show that it's logically possible to have a universe with finite (actually zero) extent at one instant, and infinite extent at all later moments. You can't ask too much of it.

I do have a sort of a similar picture to yours; a universe that actually has no first instant, but just has a time coordinate that converges when you look backwards in time. As to whether there's anything interesting to say about the pre-Planck-time epoch, who knows. --Trovatore (talk) 19:39, 14 February 2017 (UTC)[reply]

Feynman Lectures. Lecture 48. Ch.48-3 [8]

...
The television problem is more difficult. As the electron beam goes across the face of the picture tube, there are various little spots of light and dark. That “light” and “dark” is the “signal.” Now ordinarily the beam scans over the whole picture, 500 lines, approximately, in a thirtieth of a second. Let us consider that the resolution of the picture vertically and horizontally is more or less the same, so that there are the same number of spots per inch along a scan line. We want to be able to distinguish dark from light, dark from light, dark from light, over, say, 500 lines. In order to be able to do this with cosine waves, the shortest wavelength needed thus corresponds to a wavelength, from maximum to maximum, of one 250th of the screen size. So we have 250×500×30 pieces of information per second. The highest frequency that we are going to carry, therefore, is close to 4 megacycles per second. Actually, to keep the television stations apart, we have to use a little bit more than this, about 6 mc/sec; part of it is used to carry the sound signal, and other information. So, television channels are 6 megacycles per second wide. It certainly would not be possible to transmit tv on an 800 kc/sec carrier, since we cannot modulate at a higher frequency than the carrier.

— Feynman • Leighton • Sands, The Feynman Lectures on Physics, Volume I

How did he derived the number 250 and why must it be the wavelength? So I assume that the maximum of modulating signal amplitude is converted to the increasing electron emission from CRT and so white spot; the minimum of amplitude is the decreasing emission and dark spot. These spots are within the same line (one of 500), are adjacent , situated horizontally (as lines are horizontal) and have a diameter = 1 line width. Is it correct? Can the equipment modulate the carrier wave like this png so on the screen we see only one spot? Username160611000000 (talk) 05:23, 14 February 2017 (UTC)[reply]

A white spot adjacent to a black spot represents one cycle of the highest video frequency required, which is half the number of spots scanned per second. Assuming that the transition from spot to spot is a sine (or cosine) wave means that no higher frequency is needed (whereas abrupt black/white changes as in a chequerboard image would involve squarewaves and much higher harmonic frequencies). He calculates "4 megacycles per second" which is better expressed as 4 MHz. The 4 MHz video signal can be modulated on any higher frequency carrier for broadcasting. Simple Amplitude modulation would transmit sideband frequencies (F_c - 4) and (F_c + 4) MHz however this wastes precious bandwidth so the lower sideband is mostly suppressed and receivers are designed to demodulate the resulting vestigial sideband signal. The explanation serves as an introduction to the NTSC#Transmission modulation scheme that occupies a total bandwidth of 6 MHz. Blooteuth (talk) 19:14, 14 February 2017 (UTC)[reply]

Nuclear fallout

If terrorists detonate an atom bomb in the area of Wichita, KS, what amount of food and non-food crops would be contaminated by the fallout? Would that result in actual food shortages in the USA (to the point where some people would have to go without certain foods or where rationing would have to be put in place), or would it only cause increases in the price of food? If the latter, approximately how much of an impact would it have? In either case, for how long would the land remain contaminated and unusable for growing crops (i.e. how long would it be before agriculture in the area could return to normal again)? (Assume that the explosive yield of the bomb is 45 kt (the biggest nuke which those vermin could realistically obtain at present), that the detonation is at ground level (worst-case scenario in terms of radiation), and that prevailing winds prevail.) 2601:646:8E01:7E0B:9076:92A3:E19C:2F76 (talk) 06:38, 14 February 2017 (UTC)[reply]

"We don't answer requests for opinions, predictions or debate." See the page header. --47.138.163.230 (talk) 07:00, 14 February 2017 (UTC)[reply]

Would you have answered the question if I specified the location as Broken Arrow, OK? 2601:646:8E01:7E0B:9076:92A3:E19C:2F76 (talk) 10:28, 14 February 2017 (UTC)[reply]

There is a gem of an answerable question in there. Someone should be able to find references on how much agricultural land around a nuclear blast is expected to become unusable in the short term. This was once a very hot topic of research. Someguy1221 (talk) 08:21, 14 February 2017 (UTC)[reply]

Well, I've actually done the first part of the research -- I've played out this scenario on Nukemap, and it shows that with 15 knots of wind from the southwest (which may or may not actually be the prevailing wind, I don't know), the fallout plume would stretch almost as far as Topeka: http://www.nuclearsecrecy.com/nukemap/ So, with the fallout plume as shown, how much farmland would be contaminated, and how long would it stay that way -- and how much would it hurt food production? 2601:646:8E01:7E0B:9076:92A3:E19C:2F76 (talk) 10:41, 14 February 2017 (UTC)[reply]

We can generate a pretty good answer from history, and that answer is "nationwide food production and price changes would be negligible". The US has detonated over 600 kilotons of surface-level nuclear weapons within the continental US, with over 500 kilotons additionally detonated over the US at airburst levels. This is of much higher magnitude than the suggested range for a single terrorist bomb, and no widespread fallout (to the degree that it materially impacted the availability of food) was observed. Any single low-yield nuclear detonation can be safely characterized as being local in scope (however horrific that local scope may be), and the food production of the US is not constrained to any particular local scope. At most, you might find some highly-localized specialty crop that could be substantially disrupted, but not staples. — Lomn 15:42, 14 February 2017 (UTC)[reply]

Editing to add: Here's a map of fallout from the Nevada Test Site. It's clearly quite extensive over the Great Plains, so it's not as if major farming regions didn't experience the effects of several hundred kilotons of nuclear detonations. — Lomn 15:48, 14 February 2017 (UTC)[reply]

Thanks! So I understand the answer is, not much of an impact on food supplies, right? 2601:646:8E01:7E0B:64B4:64AD:FCBF:2883 (talk) 09:04, 15 February 2017 (UTC)[reply]

Here's a 70-page book, available at no cost, from the RAND Corporation: Technical Report 391, Considering the Effects of a Catastrophic Terrorist Attack (2006). If you're the sort who likes to read about these things, it's good to learn a few good sources: RAND publishes a huge library of very professional-quality research on science and policy topics like this one, and the overwhelming majority of their library is available at no cost (!) because some famous historical guy figured that the cost-benefit of an informed public, educated by free, free information, outweighed the risk of controversial information "leaking out."

On the topic of vermin, a senior member of the White House staff was recently ousted for being overly-friendly with our nation's arch-nuclear-rival.... It was his published opinion that Islamic terrorist group Al Qaeda remains as-strong-as-ever. I wonder if we can believe him!

One of my professors and a fellow pilot, Martin Hellman, worked with a few senators and politicians and researchers to found Nuclear Risk, a very alarmist organization whose primary objective, apparently, is turning intellectuals into insomniacs. They publish a lot of information on realities and speculations of 21st-century nuclear war. I find that experienced glider pilots tend to see things that we often cannot see from ground-level.

And lastly, if you haven't yet read The Bulletin, have a glance at their motives for moving their metaphorical "doomsday clock" to its most desperate setting since the invention of the hydrogen bomb in 1953. "...intemperate statements, lack of openness to expert advice, and questionable cabinet nominations have already made a bad international security situation worse."

To quote disenfranchised Arab musician Ghassan Rahbani, we're all chickens and there are foxes guarding the hen house.

Nimur (talk) 15:46, 14 February 2017 (UTC)[reply]

First of all, even if Flynn was in cahoots with the Russians (which is probably just lies created by rogue elements in our intelligence services in any case), it DOES NOT invalidate his assessment of Al-Qaida -- read Ad hominem fallacy, for God's sake! Second of all, President Trump's cabinet nominations, with a couple of exceptions, have been THE BEST in recent history -- in fact, they are THE FIRST cabinet nominees IN HISTORY to take the threat of Islam seriously! And why would ANYONE believe some raghead musician (i.e. a self-evident NON-expert, and moreover one with a VESTED INTEREST in HARMING our nation) over MULTIPLE EXPERTS in matters of NATIONAL SECURITY?! 2601:646:8E01:7E0B:64B4:64AD:FCBF:2883 (talk) 09:12, 15 February 2017 (UTC)[reply]

I'm not familiar with Ghassan Rahbani or his music. Can you explain in what way he has a vested interest in harming the US? (Preferably without resorting to racial slurs or excessive use of capitalization). Iapetus (talk) 10:26, 15 February 2017 (UTC)[reply]

Incidentally, the slur seems even sillier here than normal since AFAICT, Ghassan Rahbani does not generally wear a turban or keffiyeh. Nil Einne (talk) 14:39, 15 February 2017 (UTC)[reply]

My OpInIoN iS MoRe iMPoRtanT anD cORReCt beCAUse I usE randOm caPiTal letters? --Stephan Schulz (talk) 10:23, 15 February 2017 (UTC)[reply]

The Lebanese do not wear rags on their heads. That's a pretty impolite thing to insinuate; and in my neighborhood, it's a poor life-choice to become impolite with a Lebanese individual. Regarding headwear: there is a long and complex tradition of ~~Taqiya~~ Taqiya that is rooted in some important political history, and some of the young people are bringing it back to make an ironic statement. It might serve you well to expand your cultural horizons: here's the music in question - a hip-hop song about the difficulties of pacifism - but you kind of have to come from a rough neighborhood to appreciate that kind of music. Nimur (talk) 14:45, 15 February 2017 (UTC)[reply]

Note the answer would deeply involve human psychology. That is, how many people would be unwilling to feed their family food that is "only slightly contaminated but deemed to be safe by the government". Considering the level of distrust of government in the US, I suspect many people wouldn't believe the US government. And, if food wasn't labelled as coming from the contaminated area, that might cause people to avoid all food that might possibly be from there, instead preferring foods that were canned before the event or that don't grow in that region.

The public reaction to the food supply following the Fukushima Daiichi nuclear disaster may also be relevant. StuRat (talk) 17:30, 14 February 2017 (UTC)[reply]

The form of resulting ground contamination would be very dependent on weather conditions. Dry weather with strong winds could spread the contamination in a stripe over a hole continent. Enough rain would keep it a very local ground contamination. If the catastrophy would happen right at or near the shore of an Ocean, like in Fukushima, and the wind direction would transport most of the fallout away from the landmass, it would be minimal. --Kharon (talk) 14:46, 15 February 2017 (UTC)[reply]

It's highly unlikely that any terrorist group could gain access to a nuclear weapon and the means to deploy it. They would be much more likely get hold of some nuclear waste and make a dirty bomb - the detonation of which would have different consequences from that of an atom bomb. Richerman (talk) 17:38, 16 February 2017 (UTC)[reply]

They could buy one from the pakis (which is the scenario I had in mind, hence my specification of a 45-kt yield), or they could make their own! 2601:646:8E01:7E0B:3CD9:5D5C:57CE:D50B (talk) 10:49, 17 February 2017 (UTC)[reply]

North Korea seems more likely to sell atom bombs, as they already have just about every possible sanction on them, and are low on cash, so they have little to lose. StuRat (talk) 18:57, 17 February 2017 (UTC)[reply]

What to call '2A "self-cleavage" peptide?

There's this short peptide sequence that when it's translated from mRNA results in a break in the nascent peptide and it's called '2A'. It was or is commonly called a "self-cleavage" peptide because, I think, that was how it was once supposed to function but that is now known not to be the case. If it's not a "self-cleavage" peptide, what kind of peptide can it be called? --129.215.47.59 (talk) 14:19, 14 February 2017 (UTC)[reply]

The preferred terminology appears to be self-cleaving peptide. --Jayron 32 15:06, 14 February 2017 (UTC)[reply]

But it's not self-cleaving. --129.215.47.59 (talk) 16:13, 14 February 2017 (UTC)[reply]

But that's what it's called in the literature, so that's "what it's called" or at least a common and recognizeable term among those in the field. And what wikipedia would call an article, for the same reason. It's known that it's a misnomer (see for example doi:10.1186/s13068-017-0710-7 and references therein), but also hardly the first time a now-disproven idea has persisted in nomenclature. DMacks (talk) 16:33, 14 February 2017 (UTC)[reply]

This calls it the 2A self-processing peptide, FWIW. While this paper just calls it "2A peptide" in many places, and says (citing this, which looks likely to be the original skip paper): "2A and 2A-like sequences are now referred to as CHYSELs (cis-acting hydrolase elements) rather than self-cleaving peptides". As an article title I'd prefer the phrase in words - the acronym seems too clever by half. Wnt (talk) 17:28, 14 February 2017 (UTC)[reply]

What is subcloning? I think article might be wrong

According to the article subcloning is "a technique used to move a particular gene of interest from a parent vector to a destination vector in order to further study its functionality". What if you don't want to study its functionality? What if you just want the expression cassette out of one reporter to put in another? Is that not subcloning? --129.215.47.59 (talk) 15:04, 14 February 2017 (UTC)[reply]

I believe that's just cloning. --Jayron 32 15:07, 14 February 2017 (UTC)[reply]

The definition is wrong (well not wrong, just too specific). Moving any genetic material from one vector to another is generally referred to as subcloning. Amplifying the genetic material from its native environment (DNA, mRNA etc) into vector-based cDNA is molecular cloning. Fgf10 (talk) 15:37, 14 February 2017 (UTC)[reply]

I agree the "in order" should be a different sentence; "this might be done in order...". Cloning is to subcloning as letting (renting out) an apartment is to subletting it. So long as you are growing up many identical copies of the genetic sequence, and you started with something you'd already cloned, it's subcloning. (But subcloning is still a kind of cloning, just as subletting is a kind of letting, as after all (as the Jurassic Park novel famously pointed out) many "cloning" experimental sequences have turned out to have started inadvertently with plasmid DNA!) Wnt (talk) 17:43, 14 February 2017 (UTC)[reply]

How long does a fecal transplant last?

I was in a seminar recently and it was discussed that after an effort is made to change a person's microbial flora it reverts back to the original state and is based on their genetics. I've heard of fecal transplants as treatments for people with some gastrointestinal diseases and I've heard of these causing obesity when fecal material was sourced from an obese donor. Does the microflora return to the disease state and/or patient to original body weight? --129.215.47.59 (talk) 16:26, 14 February 2017 (UTC)[reply]

Wikipedia has an article titled Fecal microbiota transplant which covers the procedure. According to the Wikipedia article, obesity is only mentioned in passing as a "potential" application. It does not mention the mechanism by which it may work to treat obesity. --Jayron 32 16:56, 14 February 2017 (UTC)[reply]

The Q was about it causing obesity, not treating it. StuRat (talk) 17:34, 14 February 2017 (UTC)[reply]

Note that the gut microbiome also greatly depends on what the person eats, and specifically probiotics and prebiotics. A transplant won't last long if the intestinal environment does not allow for the survival of those organisms, or could last a lifetime, if it does. StuRat (talk) 17:38, 14 February 2017 (UTC)[reply]

Is that a guess, or could you give us a reference for both parts of your last sentence? Loraof (talk) 02:10, 15 February 2017 (UTC)[reply]

You want a source for the statement that organisms won't survive in an environment that doesn't allow for their survival, and could survive in an environment that does allow for their survival ? StuRat (talk) 03:30, 15 February 2017 (UTC)[reply]

I want a source for the notion that it can happen that a fecal transplant might not last too long, and a source for the notion that it could last for a lifetime. I genuinely would like a source for these, but I have no idea whether you're just guessing. Loraof (talk) 16:46, 15 February 2017 (UTC)[reply]

You must have misinterpreted what I said, so I will clarify. The purpose of the fecal transplant is to deliver microbes to improve the mix in the gut flora. However, whether those microbes flourish and reproduce, or die out in short order, depends on whether the intestinal environment is conducive to their survival. I didn't get into exactly what conditions are good for those microbes, and which are bad for them, but I see a note on artificial sweeteners has been added, with sources, at the bottom of this post, so you can take a look at those. StuRat (talk) 18:18, 15 February 2017 (UTC)[reply]

And is there any chance that the intestinal environment won't be conducive to the transplanted microbes' survival, as you extremely strongly implied could be the case? Citation needed. Loraof (talk) 21:49, 15 February 2017 (UTC)[reply]

Yes. I provided four articles from respectable journals, all of which make it very clear that consuming artificial sweeteners makes it difficult for healthy intestinal bacteria to survive. Can you explain why you believe that transplanted bacteria will survive any better than the person's own bacteria? 209.149.113.5 (talk) 12:56, 16 February 2017 (UTC)[reply]

To me, "a [fecal] transplant won't last long if ..." means that its intended effect, such as crowding out an infection of C. difficile, will soon fail. There appears to be nothing in the four linked articles about that. What I'd like is a reference that says something about fecal transplants and how long they last in the sense of their being effective. Thanks if you can find some—I'd appreciate it. Loraof (talk) 17:30, 16 February 2017 (UTC)[reply]

Actually some of the sources in the fecal transplant article address the success rate (upwards of 80%), though this doesn't say whether failure is due to the transplanted microbes failing to survive or just failing to overwhelm the C. diff. Loraof (talk) 17:50, 16 February 2017 (UTC)[reply]

Yes, you misunderstood me. I wasn't talking about "crowding out an infection of C. difficile", at all. StuRat (talk) 19:26, 16 February 2017 (UTC)[reply]

As far as which microbes survive and which die out, in any environment, it depends on many factors, like temperature and acidity, as well as the presence or absence of other microbes. I believe at least one of those 4 sources mentioned that the genetics of the person also control which microbes can survive, by altering the intestinal environment. StuRat (talk) 22:35, 17 February 2017 (UTC)[reply]

personal dispute

The following discussion has been closed. Please do not modify it.

A source for anything you say ever would be a nice start. --Jayron 32 04:00, 15 February 2017 (UTC)[reply]

Let's see a source for your claim that I've never provided a source for anything I've ever said. I've provided many sources to debunk that lie, now it's your turn to defend it. StuRat (talk) 04:28, 15 February 2017 (UTC) [reply]

An example of the claim that what you consume affects your gut flora... Many (too many to list) studies have concluded that consumption of artificial sweeteners negatively impacts gut bacteria and most of these studies correlate the altered gut bacteria with a predisposition to weight gain. [9] [10] [11] [12] (is that enough references to support the claim?) 209.149.113.5 (talk) 14:56, 15 February 2017 (UTC)[reply]

Thanks for the info. StuRat (talk) 18:21, 15 February 2017 (UTC)[reply]

According to this "Patients' gut bacteria remained healthy for up to 21 weeks after FMT" Richerman (talk) 18:31, 16 February 2017 (UTC)[reply]

Nanobots slowing aging

Will nanobots be eventually able to actually reverse aging, or will they just slow it down?Uncle dan is home (talk) 18:11, 14 February 2017 (UTC)[reply]

The article Ageing explains what we theorize about it, that it is a combination of accumulated damage (such as DNA oxidation) and programmed processes (such as DNA oxidation). Nanorobotics is an emerging technology that has potential medical applications such as directed drug delivery e.g. to cancer cells, and even assisting White blood cells protect the body. However the Ref. Desk will not give the OP a prediction about achieving Immortality (see article). Blooteuth (talk) 18:35, 14 February 2017 (UTC)[reply]

There is potential to repair DNA, such as lengthening telomeres on chromosomes and fixing errors within the DNA. Not sure if nanobots or programmed viruses would be the method. Note that fixing errors requires a "correct" version of the DNA to compare with, so cells from that individual, frozen at birth, might be useful there. Otherwise you would need to compare many damaged DNA samples to try to determine what the original undamaged version was. StuRat (talk) 18:40, 14 February 2017 (UTC)[reply]

Blood type distribution by country

Our article at Blood type distribution by country has been tagged "factual accuracy is disputed" since 2012. Does anyone have a source that can be used to either correct the article or remove the tag? --Guy Macon (talk) 18:26, 14 February 2017 (UTC)[reply]

Some possible leads to follow: [13], [14], [15], [16]. All of these were found on the first page of a Google search with the phrase blood type distribution. If you try that yourself, you may find more references you can use. --Jayron 32 18:51, 14 February 2017 (UTC)[reply]

Does porn change the sexual preferences?

Does porn change the sexual preferences? If people are given access to different types of porn, which they find appealing, would that result in a different sexual preferences? Would they ignore the types they don't have access to?--Llaanngg (talk) 19:39, 14 February 2017 (UTC)[reply]

Some good faith answers on sexual orientation, but OP was interested in sex acts. Also some meta-discussion on conduct. Collapsed for clarity.

Wikipedia has an extensive article titled Sexual orientation which discusses a myriad of factors that may or may not affect a person's sexual preferences. It does not mention any effect of pornography generally, but does contain several statements from respected organizations and researchers to the effect of " mechanisms for the development of a particular sexual orientation remain unclear" and " there is no scientific consensus about the specific factors that cause an individual to become heterosexual, homosexual, or bisexual" and "No one knows what causes heterosexuality, homosexuality, or bisexuality." and " [there is no] conclusion based in sound science at the present time as to the cause or causes of sexual orientation". So, take that as you may. --Jayron 32 19:49, 14 February 2017 (UTC)[reply]

Note that the age at which the exposure occurs may well be critical, as sexual orientation tends to be more flexible at an earlier age. Also note that if someone was exposed to homosexual porn at an early age, and became a homosexual adult, there are at least 3 possible conclusions:

They were heterosexual, and the gay porn "turned them gay".

They were genetically predisposed to be homosexual, but would have repressed this tendency if they had no "gay role models".

They would have become a homosexual adult in any case.

So, the exact nature of the cause and effect, if indeed there is any, is open for debate. StuRat (talk) 20:53, 14 February 2017 (UTC)[reply]

Do you ever read anything about actual research in this area, by actual experts who study it, or do you just make shit up as you go along as usual. "gay porn turned them gay"? Do you have any idea how absolutely backwards and bigoted that sounds given what we know about this? This is why we don't tell people what "we know" here at the reference desk. Give them reading material and let them figure it out. Jeez Stu, you've reached a new low here today. --Jayron 32 03:59, 15 February 2017 (UTC)[reply]

Do YOU have any idea how absolutely STUPID you sound accusing StuRat of being "bigoted" just for bringing up a possibility of gay porn turning someone gay? BTW, there HAVE been in fact cases of straight people becoming gay and vice versa, so this possibility is not even that far out! 2601:646:8E01:7E0B:64B4:64AD:FCBF:2883 (talk) 09:18, 15 February 2017 (UTC)[reply]

there HAVE been in fact cases of straight people becoming gay and vice versa ^{[citation needed]} - It sounds plausible enough to me, but that doesn't mean it's true. Tigraan^{Click here to contact me} 13:56, 15 February 2017 (UTC)[reply]

Well, sure, there is fluidity of sexual orientation, but recognizing that is different then the sort of "we can just make him straight" or "X made him gay" sort of thinking. A person's sexuality can be fluid, and can change throughout someone's life, but the idea that sexuality can be reliably controlled by outside factors is what leads to bullshit like conversion therapy. Yes, sexuality can change. No, you cannot make it change. --Jayron 32 14:48, 15 February 2017 (UTC)[reply]

I'm pretty sure he was just talking about how, logically, a correlation can have multiple possible explanations, and showing that there are alternatives to the theory that watching it changed them. Its analogous to saying: "If someone claims they were abducted by aliens, there are at least 3 possible conclusions: 1) They were abducted by aliens; 2) They're just making it up; 3) They imagined it". Listing an implausible explanation alongside more reasonable ones doesn't mean you support it, and is often done to emphasize how unlikely it is. Iapetus (talk) 10:37, 15 February 2017 (UTC)[reply]

My point exactly, and I added the scare quotes to emphasize that this is not what I believe. But Jayron probably knew that, as his reading comprehension skills can't possibly be that poor. He just lies about everything I do to try to make me look bad. StuRat (talk) 14:42, 15 February 2017 (UTC)[reply]

(EC) A selection of relevant scholarly articles that may be of interest:

The Influence of Pornography on Sexual Scripts and Hooking Up Among Emerging Adults in College[17] (freely accessible)

“Bareback” Pornography Consumption and Safe-Sex Intentions of Men Having Sex with Men[18](paywalled).

Does Pornography Influence Sexual Activities?[19](accessible)

Does pornography influence young women’s sexual behavior?[20](paywall)

As indicated in our article, and mentioned by Jayron, there is no general consensus of any strong effect of pornography on sexual orientation, but many researchers have documented some effects of pornography consumption on sexual preference (in a non-orientation sense), sexual acts, etc. SemanticMantis (talk) 20:57, 14 February 2017 (UTC)[reply]

Yes, I meant sexual preference in the sense @SemanticMantis used the word, that is, not as sexual orientation (homo, hetero, and so on), but as a preference for sexual activities.Llaanngg (talk) 21:31, 14 February 2017 (UTC)[reply]

February 15

Diabetes type 2 - mechanism of the problem

What is the problem of diabetes type 2? I've said it because the pancreas don't secret enough insulin, and my teacher said it's not because of secretion of the pancreas since the pancreas secretes normal insulin levels but the problem is with the cells that they receptors for the insulin are covered by fats. He added that diabetes type 1 has to do with the fact that the pancreas don't secret enough insulin but in diabetes type 2 the pancreas does secrets enough insulin. Then I've asked him again, why diabetic type 2- patients used to take insulin if they have enough insulin in their body and he answered me that it is given to the patient when the diabetes is progressive after some years that the pancreas is already out of function. Now all this information is really against what I was told in the past by another teacher (that said what I did). What's true? 93.126.88.30 (talk) 00:11, 15 February 2017 (UTC)[reply]

There are many variations of diabetes. See brittle diabetes and insulin resistance, for example. StuRat (talk) 02:24, 15 February 2017 (UTC)[reply]

Our article Diabetes mellitus says that your teacher is correct-- type 1 is due to a bad pancreas, while type 2 starts with the cells' bad insulin reception but can eventually involve the pancreas going bad as well. Loraof (talk) 02:27, 15 February 2017 (UTC)[reply]

Yes, the article answers the question quite well. Type 2 diabetes begins with insulin resistance, where cells fail to respond properly to insulin. Now, as the disease progresses this can lead to pancreatic dysfunction, as the pancreas attempts to produce more insulin to compensate for this insulin resistance, and some type 2 diabetics can eventually require insulin administration. I get the feeling the original questioner is not a native English speaker. Wikipedia is available in many languages; if you have trouble understanding the English article, see if there are articles in your native language(s). --47.138.163.230 (talk) 03:49, 15 February 2017 (UTC)[reply]

The best person to discuss this with is an endocrinologist. My general practitioner put me on insulin due to my A1C, and I put on 30 lbs. I changed to a different doctor who sent me to an endocrinoogist, who said that not only was the insulin a bad idea, but that it would eventually cripple my pancreas. He put me on various non-insulin medicines, and I lost the gained weight, and then some. I had bariatric surgery Jan 20, an am totally off all DMII meds (I had been taking three pills and a shot a day), and have lost another 30 lbs. So obviously my pancreas has not shut down yet. Seek professional advice. μηδείς (talk) 22:29, 16 February 2017 (UTC)[reply]

By which mechanism sex is considered a risk factor for arteriosclerosis?

I listened today to a lecture in which the lecturer has said that there are 6 risk factors for arteriosclerosis: 1. food. 2. smoking 3. high blood pressure 4. obesity. 5. age 6. sex. I really don't have an idea on what it's based, because after googling I didn't find source for that. But my question is about sex. What does it mean that it's a risk factor and by which mechanism sex can be a risk factor for arteriosclerosis? (Maybe he wanted to say that they are general risk factor for life rather than for arteriosclerosis. It's not clear) 93.126.88.30 (talk) 00:25, 15 February 2017 (UTC)[reply]

Apparently, men are significantly more susceptible to it than women are. My source for that is this article.[21] Google the subject and there should be plenty of entries. ←Baseball Bugs ^{What's up, Doc?} carrots→ 00:30, 15 February 2017 (UTC)[reply]

(edit conflict) Right, here "sex" means the sex of the person, not how much sex s/he has. Our article arteriosclerosis does not mention risk factors, but the related article Atherosclerosis#Risk factors does mention being male as a risk factor, with a citation. Loraof (talk) 02:21, 15 February 2017 (UTC)[reply]
- This might be why "gender" is used more and more instead of "sex". ←Baseball Bugs ^{What's up, Doc?} carrots→ 02:24, 15 February 2017 (UTC)[reply]
  - OSHA form: Q:"number of employees, broken down by sex?" A: "None (booze is more of a problem for us.)" -Arch dude (talk) 06:11, 15 February 2017 (UTC)[reply]
  - No, thats wrong. It's because gender has social components, while sex (the property, not the act) is biological (if not always binary). --Stephan Schulz (talk) 14:14, 15 February 2017 (UTC)[reply]

^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ - Yes, thanks. The worst part is when people who should know better use "gender" as a sort of euphemism for "sex". SemanticMantis (talk) 15:27, 15 February 2017 (UTC)[reply]

That's precisely the point. Whether Schulz likes it or not, "gender" is often used as a synonym for "sex". In addition to the "broken down by sex" joke, there's this old one-liner with many variant punch lines, where someone's filling out a form, and where it says "sex" they respond with something like "3 times a week." ←Baseball Bugs ^{What's up, Doc?} carrots→ 16:11, 15 February 2017 (UTC)[reply]

Wiktionary's article "Gender" points out that the meaning "sex" goes back hundreds of years, but the use with that meaning has been declining, especially in academia, for the past 50 years. Our article Sex and gender distinction says The sex and gender distinction is not universal. In ordinary speech, sex and gender are often used interchangeably.[3][4] Some dictionaries and academic disciplines give them different definitions while others do not. Loraof (talk) 16:40, 15 February 2017 (UTC)[reply]

The use of "gender" to mean sex, or even social roles correlated with sex, used to be seen as a sort of humorous intentional error, the word "gender" being properly restricted to grammar. I think what's happened in recent decades (much less than fifty years, maybe twenty or thirty) is that non-grammatical meanings have become accepted as fully legitimate. At the same time, "gender" in the non-grammatical sense may also have shifted away from biology and towards social roles. --Trovatore (talk) 16:49, 15 February 2017 (UTC)[reply]

According to Etymology online [22] the "gender as grammatical construct" sense is older, but the "gender as synonym for sex" is pretty damned old too. The grammatical meaning dates from the "late 14th century" while the gender-as-sex meaning dates from the early 15th century. It does say that the preference for using gender to mean "male or female" sex dates to the 20th century, but the meaning is almost as old as the grammatical one. Basically it only almost always meant that, at least in equal measure, to the word "sex". --Jayron 32 19:05, 15 February 2017 (UTC)[reply]

But it was a disfavored meaning; that's my point. It wasn't considered precise speech. --Trovatore (talk) 19:15, 15 February 2017 (UTC)[reply]

It was an old meaning of gender: "A class of things or beings distinguished by having certain characteristics in common; (as a mass noun) these regarded collectively; kind, sort." (OED) from the fourteenth century that was used occasionally for the class of males or the class of females as in " His heyres of the masculine gender" (1474) and "Has thou oght writen there Of the femynyn gendere" from the Wakefield Mystery Plays (1460?). In 1945, the American Journal of Psychology defined gender as "the socialized obverse of sex". Dbfirs 20:36, 15 February 2017 (UTC)[reply]

Perhaps. But it was considered jocular, imprecise, or otherwise inferior in the mid-to-late 20th century. --Trovatore (talk) 20:48, 15 February 2017 (UTC)[reply]

Was that because psychologists and sociologists began using it with a different meaning? Dbfirs 21:19, 15 February 2017 (UTC)[reply]

I suppose it's conceivable. I seem to recall that William Safire wrote in opposition to the non-grammatical usage. If someone could find his essay/chapter/whatever, it might give some insight.

But mostly it just always struck me as something Gomer Pyle would say; definitely not scientific prestige usage. --Trovatore (talk) 22:11, 15 February 2017 (UTC)[reply]

@Trovatore:What? Where? I was taught in middle school, in the late 20th c., that sex is biological and gender, though overlapping in usage, is a social concept. In essence, the "socialized obverse" from Dbfirs source. All my continued education, high school through PhD has supported that same general distinction, though detailed specifics of the definitions may vary. This is certainly true in biosciences, but also in my experience with sociology, psychology and the humanities. ('gens, gentis', from the Latin, type or kind, especially of people, underlies gender, but also genus, gentile, generate, genetics, etc. That itself comes from a PIE root *gene- "to produce, give birth, beget,") Granted, I was not around in the mid 20th c, but you should provide some sources for your repeated claim of "humorous intentional error", etc. I agree it is not proper to use "gender" to mean "biological sex" in a contemporary scientific context, but I really don't know what you're getting at for the rest. SemanticMantis (talk) 22:14, 15 February 2017 (UTC)[reply]

Well, this was the way I heard it anyway. There's a hint of it in the EO link that Jayron gave, though it doesn't put a date on it. As I say, I think there's something by Safire somewhere, but I don't have it to hand. --Trovatore (talk) 22:19, 15 February 2017 (UTC)[reply]

I don't have access to the Saffire opinion, but the OED says: " In the 20th cent., as sex came increasingly to mean sexual intercourse (see sex n.1 4b), gender began to replace it (in early use euphemistically) as the usual word for the biological grouping of males and females. It is now often merged with or coloured by sense 3b" [and 3b, with cites from 1945 onwards, is "Psychol. and Sociol. (orig. U.S.). The state of being male or female as expressed by social or cultural distinctions and differences, rather than biological ones; the collective attributes or traits associated with a particular sex, or determined as a result of one's sex. Also: a (male or female) group characterized in this way."] Dbfirs 22:30, 15 February 2017 (UTC)[reply]

Viagra does cause delayed back ache. Perhaps these phenomena are related? μηδείς (talk) 22:19, 16 February 2017 (UTC)[reply]

Feynman Lectures. Lecture 48. Ch.48-4 . Refractive index < 1, phase speed > c [23]

...
In other words, for the slowest modulation, the slowest beats, there is a definite speed at which they travel which is not the same as the phase speed of the waves—what a mysterious thing!

— Feynman • Leighton • Sands, The Feynman Lectures on Physics, Volume I

What does he mean by "slowest"? Very low frequency of modulating wave?

A part from words Let us see if we can understand why to the end of the chapter is also obscure.

Now because the phase velocity, the velocity of the nodes of these two waves, is not precisely the same, something new happens. -- He considers x-rays. X-rays have a speed $v_{\text{x-rays}}=c/n$ . How could it be that phase velocities are different? Even in the glass (or carbon) two x-ray waves must propagate with equal speed.

$\definecolor {myorange}{rgb}{0,0.38,0.52}\color {myorange}dk/d\omega =1/c+a/\omega ^{2}c$ -- When I express the formula (48.14) like this: $\omega ={\tfrac {1}{2}}(ck\pm {\sqrt {(ck)^{2}+4a}})$ and differentiate, I get: ${\tfrac {d}{dk}}\omega ={\tfrac {d}{dk}}{\tfrac {1}{2}}(ck\pm {\sqrt {(ck)^{2}+4a}})={\tfrac {1}{2}}(c\pm {\tfrac {c^{2}k}{\sqrt {(ck)^{2}+4a}}})$ . But Feynman got ${\tfrac {c}{1+a/\omega ^{2}}}$ . Why? Username160611000000 (talk) 07:52, 15 February 2017 (UTC)[reply]

Group velocity might help you. Tigraan^{Click here to contact me} 13:58, 15 February 2017 (UTC)[reply]
- The images in the article show group speed ≠ phase speed. This case is not explained by Feynman yet.
- I assume next: with frequency $\omega _{2}=8\pi$ (Fig. 48–1) the refractive index will be $n_{2}=1-{\tfrac {Nq_{e}^{2}}{2\epsilon _{o}m(\omega _{_{2}})^{2}}}=1-{\tfrac {a}{(\omega _{_{2}})^{2}}}$ . So the phase speed will be $v_{p;2}=c/n_{2}$ .
  And by analogy for $\omega _{1}=10\pi$ we have $v_{p;1}=c/n_{1}<v_{p;2}$ .
  Is it that what Feynman meant?
  Username160611000000 (talk) 18:00, 15 February 2017 (UTC)[reply]
- WRT formula :
  
  ${\tfrac {1}{2}}(c\pm {\tfrac {c^{2}k}{\sqrt {(ck)^{2}+4a}}})={\tfrac {1}{2}}(c\pm {\tfrac {c^{2}({\tfrac {w}{c}}-{\tfrac {a}{wc}})}{\sqrt {(c({\tfrac {w}{c}}-{\tfrac {a}{wc}}))^{2}+4a}}})={\tfrac {1}{2}}(c\pm {\tfrac {cw-{\tfrac {ca}{w}}}{\sqrt {(w-{\tfrac {a}{w}})^{2}+4a}}})=$
  $={\tfrac {1}{2}}(c\pm {\tfrac {cw-{\tfrac {ca}{w}}}{\sqrt {w^{2}+{\tfrac {a^{2}}{w^{2}}}-2a+4a}}})={\tfrac {1}{2}}(c\pm {\tfrac {cw-{\tfrac {ca}{w}}}{\sqrt {w^{2}+{\tfrac {a^{2}}{w^{2}}}+2a}}})={\tfrac {1}{2}}(c\pm {\tfrac {cw-{\tfrac {ca}{w}}}{\sqrt {(w+{\tfrac {a}{w}})^{2}}}})=$
  $={\tfrac {1}{2}}({\tfrac {cw+{\tfrac {ca}{w}}\pm cw\mp {\tfrac {ca}{w}}}{w+{\tfrac {a}{w}}}})={\begin{cases}{\tfrac {cw}{w+{\tfrac {a}{w}}}}={\tfrac {c}{1+{\tfrac {a}{w^{2}}}}}\\{\tfrac {\tfrac {ca}{w}}{w+{\tfrac {a}{w}}}}={\tfrac {c}{{\tfrac {w^{2}}{a}}+1}}\end{cases}}$
  
  It's strange, but second answer doesn't fit ...
  Username160611000000 (talk) 20:16, 15 February 2017 (UTC)[reply]

What type of person makes all the factory parts and programs them to work?

In a factory, everything seems to be automated. What type of person invents all the factory parts and programs them to work properly to create lots of things in a relatively short period of time? What skills and knowledge are needed? Are there any books about this matter? 166.216.159.7 (talk) 15:42, 15 February 2017 (UTC)[reply]

Designing machines is done by engineers. --Jayron 32 16:26, 15 February 2017 (UTC)[reply]

Also, to expand on that, no one single person would be expected to design an entire factory all by themselves. Hundreds of engineers working in teams would do that. --Jayron 32 16:29, 15 February 2017 (UTC)[reply]

See Manufacturing engineering and Industrial engineering. Loraof (talk) 16:31, 15 February 2017 (UTC)[reply]

Well, also it should be noted that, depending on what the factory is making, there would be a dozen or more engineering sub-disciplines involved. After all, the robot itself may be designed by a mechanical engineer, while wiring would be done by an electrical engineer. If (for example) it was a chemicals factory, there would be chemical engineers to handle designing reaction vessels. It goes on and on. No one person would be expected to do all of those jobs, it would require many dozens of engineers from a wide variety of disciplines. --Jayron 32 16:47, 15 February 2017 (UTC)[reply]

Design of things is still the design of things, whether they're made by hand, by manually-controlled machine or by fully-automated robot. Many of the design issues, either the aesthetic design of them or their engineering design is still much the same.

Manufacture by automated machine relies on the CAD / CAM / CNC cycle. One might use CAD to draw something that's then made entirely by hand, one might begin to design for robot manufacture by using a pencil and paper, but somewhere along the route an automated manufacture involved moving into the CAM / CNC world.

The first CNC began with punched cards and punched tape, first for the Jacquard loom and later for milling machines. These are powered, manually controlled machines, where their hand controls are replaced by power controls under the direction of the tape's instructions. G-code (from the 1960s) was an important step for this (it's still around today) where very simple instructions are given to a dumb machine in the form "move this control so far, move that control a little". Writing G-code was long recognised to be a long and tiresome task, using much the same skills as a manual machinist used for manual machining.

CAD has been around for as long as computers were available. It could be said to begin in the 1940s, but this was theoretical modelling of complex engineering (nuclear engineering, aerodynamics and fluid dynamics for gas turbines) rather than an interactive "design" process. CAD, as we'd know it now, begins in the late 1970s with graphical terminals and minicomputers.

CAM joins up the design and control aspects of this: it embodies the machinist's knowledge of how to use a machine to make a shape. CAM becomes increasingly sophisticated and automated: from an early beginning in checking the low-level and error-prone G-code for validity, or generating batch machining tasks (e.g. remove 0.5" of material in repeated 0.025" steps, starting from the same place), through to modern 3D printing. 3D printing can specify a solid shape by CAD, but the CAM not only works out how to move the print head to make the shape but can also transform the hand-drawn solid automatically into a hollow honeycomb, saving material and print time.

Factories are also about more than machining. I spent much of my career making production line machines to assemble or test assemblies, particularly in car factories. These didn't look like "robots", or even robot arms, they mostly resembled a conveyor belt with workstations for each task. An operator might manually place a gear on an axle, some screws are automatically fed from a magazine screwdriver and driven home, then a power press drives a bearing into place. Finally a rotating shaft measures the force needed to turn the assembly and if this is within the expected limits, to check that everything turns freely. Skills for this (a good job market) ranges from general mechanical engineering design, specific production engineering (there are college degrees in that speciality), electrical work, PLC programming and (my part) general computer programming for connecting user interfaces (see SCADA) to machinery and usually doing some statistical processing for tasks like SPC. Some projects were purely for testing, such as engine test cells and dynamometers.

There is a massive literature and training organisation around these industries. Andy Dingley (talk) 18:42, 15 February 2017 (UTC)[reply]

Its almost never only one person. Naturally its not obviouse to outsiders how many problems need to be solved to build a working, reliable factory. Experts on automation may seem like the real core of designing a factory but they only have basic knownledge of for example electrical installations, architecture, work security, workflow or finances.

Ofcorse, if you plan a multimillion investment like a factory you want to make shure for example some machine gets placed on a proper solid floor that can withstand all the forces and also doesnt get you in trouble if some oil leaks on to it. Just imagine some goverment inspector who wants ot check out your "factory" slipping and braking his arm on some oily patch next to a machine you just put there thinking what could go wrong. You have to think of everything and ofcourse thats even a challenge for a team of experts, let alone one who is specialized on Automation. --Kharon (talk) 02:05, 17 February 2017 (UTC)[reply]

I worked in the body panel press shop at Pressed Steel Fisher in Swindon for one job. The steel sheets (maybe 6' square) are greased before they go into the presses. The floor was of wooden blocks. As usual, I was wearing a suit and tie - the few concessions were that the tie was a clip-on, I wore Doc Martens and I kept a large boilersuit handy if I actually had to climb into a machine. In Swindon though, this wasn't enough - that plant was filthy, in a clean sort of way. The grease from the sheets got everywhere, including the wooden floor. I had to nip out at lunchtime and buy myself a set of hobnailed boots just to stay upright. I also purchased a picnic set - clean plastic table, clean chairs and a picnic umbrella, which I set up as a computer workstation alongside the machine for whilst I was in there. Naturally I set the umbrella up too - I'd paid for it, I was having it!

I still preferred it to the BMC A-Series engine cylinder head machining line. They were made from a particularly graphitic grade of cast iron, which threw a haze of conductive black dust into the air. That got everywhere and caused no end of short circuits. Our computers had to be IP66 waterproof to survive. Andy Dingley (talk) 15:06, 17 February 2017 (UTC)[reply]

Walking on the moon

If I applied the same forces with my feet as I do on earth, but was skipping (like the astronauts did) on the moon's surface, how high off the surface would I be jumping? --31.92.250.145 (talk) 18:17, 15 February 2017 (UTC)[reply]

It would depend on how high you could jump on earth. ←Baseball Bugs ^{What's up, Doc?} carrots→ 18:34, 15 February 2017 (UTC)[reply]

Quick approximation is that the lunar gravity is 1/6th that of Earth. You're also going to jump less well encumbered by a space suit, and carrying the extra weight of a space suit, rather than just running shorts.

But (comparing your performance on Earth whilst carrying the weight of a spacesuit) you could jump to six times the height you could reach on Earth. Andy Dingley (talk) 18:44, 15 February 2017 (UTC)[reply]

The relevant equation is

E=mgh

, where

E

is the amount of energy you put into the jump,

m

is your mass (plus that of anything you're carrying),

g

is the gravity of the planet or moon you are on, and

h

is the height you jump. This can be re-arranged to

h={\frac {E}{gm}}

. Assuming you can apply the same amount of energy into the jump (it will be over shorter period), then, as, Bugs said, the height you jump is inversely proportional to the gravity. LongHairedFop (talk) 19:33, 15 February 2017 (UTC)[reply]

Yeah but the astronuts didnt seem to be jumping that high: only say 150cm. They should be diong a few feet at least.Also, why are the in slow motion?31.92.250.145 (talk) 22:07, 15 February 2017 (UTC)[reply]

My guess would be that they had been trained to jump slowly and gently, to avoid going too far or too fast. Even in low gravity, inertial mass and momentum remain unchanged, so collision injury is just as serious. The apparent "slow motion" is a direct result of acceleration from the moon's gravity being only one sixth of that on Earth. Dbfirs 22:22, 15 February 2017 (UTC)[reply]

They also had to be careful, because if they were to trip and fall, they could damage the suit or the equipment pack, which could be fatal. ←Baseball Bugs ^{What's up, Doc?} carrots→ 22:32, 15 February 2017 (UTC)[reply]

I seem to remember at least one of the moonwalkers falling over with no apparent ill effects. Anyway, why do you have to bounce around in low gravity? And what was the mass of the spacesuits etc compared to their unsuited body mass?31.92.250.145 (talk) 22:56, 15 February 2017 (UTC)[reply]

There are videos of astronauts falling (see this). In photos, Buzz Aldrin has dirt near one knee, but I think that he said that he didn't remember falling down. As far as jumping on the Moon, the space suit is restrictive. It also added 200 pounds on Earth, but if an astronaut weighed 175 pounds on Earth, that would be like (175+200)/6 = 62.5 pounds on Earth. If the spacesuit were completly flexible (it wasn't) then you should be able to jump nearly three times as high (with the added weight) as you can on Earth. The reason that they appear to be moving in slow motion is because of the acceleration of gravity and his first law of motion, F=ma, and the equation for how far a body falls under gravity. If you work through the math, it takes about 2.5 longer for something to fall the same distance on the Moon as on Earth. The same thing applies when something is going up. And bouncing around was the best way to move. During the Apollo 11 moonwalk, Aldrin demonstrated several methods of moving. Bubba73 ^{You talkin' to me?} 00:07, 16 February 2017 (UTC)[reply]

Some time in the last 50 years I have read [sorry, no specific reference yet found] that the skipping or 'galumping' gait adopted by the lunar astronauts was what they quickly found to be the surest method of progression in the conditions. The lower gravity means both that a given muscular effort causes a greater rise, and that foot/ground friction is much reduced. Many of us will have experienced the advantage of 'galumping' when proceeding downhill at speed (somewhat comparable to the lower gravity situation), and also of the adjustments necessary when walking on slippery ice; the combination of the two is out of most people's experience. Our article Apollo 11, under 'Lunar surface operations', includes the following text – note the last sentence:

"Armstrong said that moving in the lunar gravity, one-sixth of Earth's, was "even perhaps easier than the simulations ... It's absolutely no trouble to walk around."^[36] Aldrin joined him on the surface and tested methods for moving around, including two-footed kangaroo hops. The PLSS backpack created a tendency to tip backwards, but neither astronaut had serious problems maintaining balance. Loping became the preferred method of movement."

The best gaits to use in various gravity strengths (and on various surfaces) is a difficult matter to research, although experiments (as preparation for possible human exploration of Mars, whose gravity is about 1/3 ours) have been done by suspending subjects by sprung wires, sometimes from an overhead travelling framework – relevant videos I have seen may be findable on the usual sites, here are a couple new to me:

https://www.youtube.com/watch?v=LvnDIDqcfGI

https://www.youtube.com/watch?v=5MraTpKa7a8

As yet there has not (to my knowledge) been a conclusive finding for Martian surface gravity (approximately 1/3 of ours). The poster formerly known as 87.81.230.195} 90.203.118.169 (talk) 04:11, 16 February 2017 (UTC)[reply]

The lunar gait was described as hopping or kangaroo hopping, rather than skipping. The point is that under the low gravity they found it easy to hop with both legs together, but that as the suit limited movement of each leg going past the other, it was much easier to hop with both together.

When falling over they tried to either fall forwards onto one knee (under the low gravity this would be low risk) or else to fall backwards. The PLSS rear pack was much more robust than the front equipment and cameras, also it left the astronaut lying on top of the PLSS rather than under it, making it easier to get up again. Andy Dingley (talk) 10:08, 16 February 2017 (UTC)[reply]

One light controlled by two switches

Sometimes there are two switches in different locations for one light. When you turn off the light with one, you can turn it back on with the other. Is there a diagram somewhere that shows how this is done? Is it somewhere at Multiway switching? I can't imagine how it could work. Many thanks, Anna Frodesiak (talk) 23:12, 15 February 2017 (UTC)[reply]

Yes, Multiway switching#Traveler system is the usual way. Andy Dingley (talk) 23:15, 15 February 2017 (UTC)[reply]

Thank you, Andy! I saw that and didn't get it, then stared at it for longer and now I totally get it. Cheers. :) Anna Frodesiak (talk) 23:27, 15 February 2017 (UTC)[reply]

(asside) When I was a child, my uncle, an engineer showed me how two switches do this. He challenged me to figure out how to do it with three switches. I couldn't do it. The third switch has to be a different type. Bubba73 ^{You talkin' to me?} 19:20, 16 February 2017 (UTC)[reply]

February 16

Hiding numbers in a crossed-eye stereogram.

I'm making a bunch of puzzles for an Escape Room. These puzzles need to be mildly difficult to solve - but not impossibly so. My particular need is to creatively hide a 4 digit number "in plain sight" to open a combination lock as one step in a multi-stage puzzle.

I had an idea for way to hide a number in a "crossed eye stereogram" (see Stereoscopy) like this one:

(You cross your eyes until one picture overlays the other - then it all pops out in 3D - you can try it out if you sit back a ways from your monitor).

What I'm ultimately wanting to do is to place a grid of random numbers into just the right-hand image (perhaps have them written on a chalk-board inside the photo) then to place the red pattern into the corresponding place on the chalk-board in the left-hand image.

When you 'fuse' the two images into one, I hoped that the red circles would highlight four of the numbers with the lines between showing the order they go in. When you put something in one image and not in the other, it kinda looks transparent or something. You'd only be able to figure out the combination by crossing your eyes or using a 3D viewer which I'd leave lying around someplace else.

I've never seen this trick done for hiding numbers, so to test out my idea, I made this super-simple test case:

My hope was that when you viewed the image by crossing your eyes (possibly by using a Stereoscope) to align the two pictures into one - the red pattern would indicate the four numbers in the grid that you need to open the combination lock.

What actually happens is really weird and totally not what I expected! A fuzzy region around the red pattern seems to "erase" the nearby numbers in the right-eye image!

Swapping the left and right images produces the exact same response (so it's not like the effect is caused by "left-eye dominance" or anything).

So two questions:

What is happening? (I'm curious!)
Is there anything I can do to make it work the way I'd hoped it would?

SteveBaker (talk) 04:23, 16 February 2017 (UTC)[reply]

That's your blind spot - the "scotoma" or "optic nerve disk." The actual physiology is a bit complex - suffice to say that all humans have a spot in the almost-exact-center of each eye's visual field in which there is no visual perception, and your brain just "blips" it out so you don't notice it! It is the enabler for many an optical illusion, and it's also described in the PHAK as a risk: you can't see tiny dots in the sky when you stare straight at them! In your set-up, your circles draw the viewer's eye directly to the number, causing it to fall in to their blind spot. In the PHAK, they do the exact same thing with a diagram of an airplane, demonstrating how you might not see something that's flying right toward you unless you make a concerted effort to constantly scan your visual field.

You need a "bigger" number field - the actual scotoma is tiny, so if your numbers (and circles) are even a bit larger, you won't have the problem. Or you can try to train or instruct your viewers to visually scan off-center...

Nimur (talk) 05:05, 16 February 2017 (UTC)[reply]

I don't think it's the blind spot. When I close one eye, the image the other eye is pointed at returns to normal. I suspect the culprit is that the images are too dissimilar. It's difficult to keep them aligned, and the brain may be blinding you to incongruous parts of each image. Someguy1221 (talk) 05:13, 16 February 2017 (UTC)[reply]

With Steve's setup, he's forcing the number into the blind spot by requiring you to align and focus your eye in a specific location. The instant that you close one eye, saccade occurs, and your brain and eye work together to scan over the whole visual field, moving any specific location out of your optic disk for at least part of the time - helping your brain to fill in the little blip.

Just like the diagrams in the textbook, Steve's setup is actually working against your physiology and visual perception system, forcing a specific alignment, and encouraging your eye not to scan the target-object out of its blind spot. Nimur (talk) 05:22, 16 February 2017 (UTC)[reply]

No, I just used one of those diagrams to locate my blind spot. It is not remotely close to where my eyes are focusing while overlaying the images. Someguy1221 (talk) 05:53, 16 February 2017 (UTC)[reply]

At first sight, I liked the blindspot explanation - but on reflection, I don't see how it can be true. Why should the numbers always disappear and the red diagram not? Flipping the entire image left/right doesn't change the results. On the face of it there is symmetry everywhere - so why is the red diagram clearly visible while the numbers always fade out? SteveBaker (talk) 13:32, 16 February 2017 (UTC)[reply]

In general, your brain can't overlap disparate images very effectively - rather than seeing one combined image, you see both simultaneously. For an example, see the film Goodbye to Language, which is in 3D but sometimes uses totally different images in the left and right channels. You never see these overlap - rather, they "pop" against each other, and your attention is always drawn to sudden movements or bright/sharp objects. You're getting a similar effect here - I suspect the reason that the red circles are so visible is that they have sharp edges and clear details while the numbers just form a wall of noise, so your brain always focuses on them. Smurrayinchester 08:57, 16 February 2017 (UTC)[reply]

That does seem to be the case here. I probably need to do some more experiments. SteveBaker (talk) 13:32, 16 February 2017 (UTC)[reply]

Bear in mind that some people, myself included, can't 'see' stereograms. Have never been able to. I guess in your escape room scenario there will be a group, and most people will be fine, but still. 131.251.254.154 (talk) 10:47, 16 February 2017 (UTC)[reply]

OFF-TOPIC: Stereoblindness is a well-understood phenomenon - and if both of eyes work then it's possible to cure it. (See Stereopsis recovery). The good news for people with stereoblindness is that brain plasticity often allows people recover the capability. People who do this (See Susan R. Barry), claim to see the world in an entirely new and richer way! So I encourage you to seek out an expert.

From the escape room perspective, stereoblindness affects about 5% of the population and our problems are designed to be solved by a team. The smallest team allowed is usually 4 and the largest is 8. The odds of four of them all being stereoblind is vanishingly small (5% x 5% x 5% x 5% = 0.0006%). We don't shy away from problems that colorblind people can't solve for the same reason - and a reasonably good IQ is needed to be successful too! SteveBaker (talk) 13:20, 16 February 2017 (UTC)[reply]

Perhaps not what you have in mind, but personally I find it much easier to combine overlapping images by putting one on top of the other and holding them up to a strong light. Of course, then you wouldn't be using the stereoscope, etc. I wonder if a flip book or zoetrope would be any more effective? Though again that would require a different approach. Dragons flight (talk) 11:09, 16 February 2017 (UTC)[reply]

Note that the image of the polar bear is made for parallel-eye viewing, not crossed-eye viewing. If you try it with crossed-eye viewing, the depth is reversed. And I never managed parallel-eye viewing without a stereoscope, although I've no difficulty with crossed-eye.

If, in the image with the yellow squares, I look with my left eye at the number field or with my right eye at the red lines, from a reasonable distance from my monitor, the other feature falls into my blind spot. It's far enough from the centre of my field of view not to interfere with the overlapping images. But strong features, like the red lines on yellow background, override weak features, like a wall of numbers. Furthermore, the images have too little in common. When I don't focus on the edge between the yellow and the grey areas, I can't keep the images aligned. On the other hand, I often see those "Find the 10 differences"-images on yoghurt bricks and the like, and I can easily solve them by overlapping both images. I can see the differences blink whilst the rest of the image is static.

If you want to do something with stereograms, what about hiding the numbers in the third dimension of an autostereogram? I prefer them with crossed-eye viewing (so that's the opposite of most examples in that article), but even if you view them the wrong way, the depth is just reversed but the numbers should still be readable. PiusImpavidus (talk) 11:38, 16 February 2017 (UTC)[reply]

I had already planned to use an autostereogram to provide an instruction for another puzzle. A decent escape room needs maybe ~30 puzzles to solve in order to keep a group of 4 to 8 people busy for an hour - so there is room for all kinds of sneakiness. The thing about autostereograms is that people would completely expect to have to view them to get the answer - this one would be a little more subtle (if it actually worked!).

I never understand the difference between "parallel viewing" and "crossed-eye viewing" - it seems that what I have to do is to relax my gaze and let my eyes cross in order to see the polar bear...and when I do that, it seems to have the correct depth information.

What started me off on this is that McDonalds are currently giving away a Batman-themed stereogram viewer with their "Happy Meals" and one of them got abandoned at my house by the grandkids. Since my escape room is themed as "Escape from toyland" having a children's viewer present seemed like an opportunity too good to miss! The polar-bear image works in their viewer - so I guess that "parallel viewing" is what I mean here.

SteveBaker (talk) 13:20, 16 February 2017 (UTC)[reply]

"Crossed eye" means that a line drawn out from the pupil of each eye would cross, while parallel means they go off to infinity. "Relaxing" your gaze makes your eyes parallel. Guess: The catch I think is that some people have eyes further apart then others, and the ones with their eyes furthest apart find existing parallel eye stereograms easiest to read, so they make more... for people like them. The ones who are narrower aren't programmed to have their eyes point apart in two different directions, so they never have a chance. Wnt (talk) 14:40, 16 February 2017 (UTC)[reply]

I believe you have encountered the effect known as binocular rivalry. It is well known in perceptual psychology and has been studied quite extensively. It has nothing to do with the blind spot. Looie496 (talk) 14:09, 16 February 2017 (UTC)[reply]

I agree - as the article describes, I saw the numbers blotted out by the shape, then perfectly visible with the shape also. The catch though is that the numbers don't seem to blot out the red lines so intensely, so it is entirely possible for me to find the circled numbers - IF there are enough cues to line the shapes up accurately. Also, there is a sort of "lasso area" around the red line figure that blots out the numbers, but further away there is no interference, and the way in which that area is delineated is likely to be intensely interesting. This could be fun to look up further. Wnt (talk) 14:27, 16 February 2017 (UTC)[reply]

Fair gambit! I can concede that this may be a purely psychoperceptual illusion, like binocular rivalry, and that may even be a better explanation for the effect than positing a physiological cause like the optical disk blind spot - besides, I can't see what you see, so maybe we're seeing (and explaining) different effects! This raises some fun questions about testability and falsifiability as it pertains to visual illusions: how could we test the root cause? If it's your blind spot, scanning the field should make it go away (and does, for me at least). I'm not certain that proves very much, though!

At the very least, psychological and perceptual illusions can coexist with real physiological visual artifacts - it could be a combination of all of the above!

Nimur (talk) 06:57, 17 February 2017 (UTC)[reply]

I'd like to suggest that you use a rather complex image for the stereograph, but then make the hidden message different in the two eyes. When looking at a stereograph, any details that don't "match" stick out like a sore thumb. You notice this when using vintage stereo cards that have a scratch or something on them. It feels like the scratch is flashing as your two eyes fight over what version of the image is 'correct'. (You can intentionally exploit this effect to quickly solve one of those 'spot the differences' puzzles they sometimes print in newspaper comic pages.) ApLundell (talk) 17:27, 16 February 2017 (UTC)[reply]

 ASCII-art stereogram:

 Here is an ASCII stereograms.  View with a monospace font.
 To see the 3d effect, you need to focus your eyes such that the two
 adjacent "X" characters at the top look like three. Once you've done 
 that, wait a few moments for your eyes to get used to it, then slowly 
 look down at the rest of the image.

                             X         X
 .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .
  .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .   .
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--Guy Macon (talk) 19:06, 16 February 2017 (UTC)[reply]

When I look at the image with yellow background, I get the stereo effect, but the red circle's pattern does not "lock" on the random numbers. Circle's pattern kind of vibrates in horizontal position. Even then, I can see that the area of red circles overwrites the background numbers. But I noticed, with some efforts, I can see the numbers but this make the circle kind of disappear. I was able to focus on either on circle or on number at a time, and was able switch focus as desired. Therefore, to get images in locked state, I thought I need a matching pattern in remaining part of both images. Then actually I cut the red circle's pattern and pasted on the right side of bear on the left bear image, and random number pattern on similar position on the right bear image. And then when I looked, I got the circle pattern nicely locked on the numbers. And in stereo view, I could still focus on either circle and on number, and flipping the focus revels the desired numbers! Give it a try. manya (talk) 05:36, 17 February 2017 (UTC)[reply]

If you don't mind it not being a proper stereogram (like the one with the polar bear), there's something called SIRDS (single image random dot stereogram.) There are generators for that kind of thing on the internet if you google. They take an image that contains a mask and create a "Magic Eye"-type image that contains the outline of what was in the original image. When viewed properly it will appear embossed Asmrulz (talk) 17:06, 17 February 2017 (UTC)[reply]

Here's a random one from google search results: http://pictureimage.whak.com/signs/stereogram/?text=123

It takes a string of text and generates a SIRDS image with the string hidden in it. I personally couldn't "acquire lock" on the image but I think it's because I'm viewing it on a monitor. It'll work if you print it out (perhaps scale up a bit) Asmrulz (talk) 17:14, 17 February 2017 (UTC)[reply]

Identify a tadpole shrimp (Triops)

Is this photo a Triops granarius or a different species? Found in an ephemeral pond near Victoria West, Northern Cape province, South Africa. The image in the article is too small and unclear to properly compare it. Roger (Dodger67) (talk) 07:42, 16 February 2017 (UTC)[reply]

Hmmm, a quick search online yields an essay suggesting that there is some work needed on the taxonomy. [24] I thought someone must have looked at the DNA, so I went to PubMed and found this, which should be useful. But I'm a bit reluctant about using Sci-Hub from this location, and who the heck has access to "Zootaxa"? So I'll leave it to you to go over what they say about the two other species they think they can distinguish there. Wnt (talk) 14:35, 16 February 2017 (UTC)[reply]

Thanks Wnt, leaving the taxonomic fights aside, it seems that granarius (by whatever name) is the common species in the area concerned. Roger (Dodger67) (talk) 16:59, 16 February 2017 (UTC)[reply]

does exercise oxidize us

does exercise oxidize us? Is this unhealthy somehow? — Preceding unsigned comment added by 31.4.145.73 (talk) 15:42, 16 February 2017 (UTC)[reply]

This may be useful for your research. --Jayron 32 15:47, 16 February 2017 (UTC)[reply]

In the literal sense, yes, because the food you eat is oxidized to release energy for your body to use. As with anything, extremely excessive physical activity can be bad for your health, but the health benefits of reasonable amounts of exercise are well-documented. If you live in the developed world, you're at much greater risk of not getting enough physical activity, which can lead to all kinds of health issues. See also oxidative stress for the general topic of cell damage caused by oxidation reactions. --47.138.163.230 (talk) 01:56, 17 February 2017 (UTC)[reply]

We can read a lot about this subject in scientific articles and our own articles as mentioned above. But we need to consider here that our understanding of the processes involved here is still quite new while the biological processes are very ancient, many of these date back to the time that organisms first started to use oxygen about 2 billion years ago. Evolution has led animals that have made the best out of all these processes, so a naive way of thinking that heavy exercise may not be healthy due to the large amount of oxidation, probably does not reflect reality. The opposite, taking a lot of anti-oxidants has been put to rigorous tests, with typically negative outcomes, e.g. taking a lot of vitamin C impairs recuperation after heavy exercise. Count Iblis (talk) 02:26, 17 February 2017 (UTC)[reply]

^{[citation needed]} for your last claim, preferably with a WP:Medrs compliant source if you can. It's not mention by the ref linked by Jayron32 above. Nor in vitamin C which only mentions "A study in rats and humans suggested that adding Vitamin C supplements to an exercise training program lowered the expected effect of training on VO2 Max. Although the results in humans were not statistically significant, this study is often cited as evidence that high doses of Vitamin C have an adverse effect on exercise performance. In rats, it was shown that the additional Vitamin C resulted in lowered mitochondria production.[40]". I assume we're talking about humans not rats since the OP clearly is and in any case I don't think this single study really belongs in our article (but that's something for the article talk page). And "It has not been shown effective in prevention or treatment of the common cold, except in limited circumstances (specifically, individuals exercising vigorously in cold environments).[25][needs update][26]".

I'm not suggesting that vitamin C supplementation after or before heavy exercise has any benefit. Rather most likely there is no benefit nor negative, e.g. as mostly suggested by this (non medrs) source [25], e.g. "The overwhelming consensus of a fairly large number of well-conducted investigations is that vitamin C has no ergogenic effect in persons who are not vitamin C deficient" and "The overwhelming consensus of the literature is that long- or short-term supplementation with vitamins E or C has no ergogenic effect on submaximal exercise performance, aerobic capacity, or muscle strength". Yes this only talks about ergogenic effect but it's silly to think they wouldn't have mentioned if there was a well supported ergolytic effect.

Note this doesn't mean it's a good idea to supplement as some people claim because it probably has no significant negative effect. Since you have no reason to think it has a positive effect either nor to think a positive effect is more likely, that doesn't make sense. And there is the minor (presuming you aren't talking about extreme amounts) stress you're putting on your body excreting all that excess vitamin C.

Nil Einne (talk) 06:28, 17 February 2017 (UTC)[reply]

How do I make a factory?

I really like watching How It's Made series on YouTube. Everything is automated. There are machines that control everything in high speed! I wish I can make my own factory. What skills and knowledge and how much money do I need to build my own factory? How many subjects in physics and chemistry do I have to learn about before I can make my own factory? How do I extract metal ore from the ground? How do I convert metal ore into usable pieces of metal? How do I make a wire? Where do I start in the process of making an automated machine? 66.213.29.17 (talk) 19:51, 16 February 2017 (UTC)[reply]

Are you the same person who asked the question about factories a few days ago? If so, the answers are there still. To reiterate: One person does not make a factory. Hundreds do. It is beyond the scope of ability and knowledge and time and resources for a single person to handle the entire thing. Please scan up this page for responses to this question the last time it was asked. If there are more specific questions that you need answered, we'll try to help as well. --Jayron 32 20:01, 16 February 2017 (UTC)[reply]

#What type of person makes all the factory parts and programs them to work?

For the historical aspects, some good reads are John G. Landels'. Engineering In the Ancient World. and L T C Rolt's. Tools for the Job.Andy Dingley (talk) 20:24, 16 February 2017 (UTC)[reply]

We have articles on mining, ore and metalworking. I recommend typing some of your keywords in to our serach box, and then reading the articles. We can help you read up on these things, and answer questions about them, but we can't teach you the entire field of industrial engineering and design of factories. SemanticMantis (talk) 21:52, 16 February 2017 (UTC)[reply]

"How do I make a factory?" is not a science question. It should be asked on another page. DrChrissy ^(talk) 21:58, 16 February 2017 (UTC)[reply]

The same IP user posted this question about a factory. Blooteuth (talk) 00:44, 17 February 2017 (UTC)[reply]

For a factory on the human scale I might recommend RepRap and other rapid prototyping and 3D printing. For a chemistry factory, microfluidics is a growing field that carries out whole reactions in a tiny module. While these technologies currently have significant limitations relative to conventional methods, they seem to have great potential, and they allow new methods - for example diazomethane can be produced and used in a microfluidic set-up, even though a traditional chemist might not dare to come within sight of a flask of it. Factories have largely shed their human workers for machines; arguably the next step is to make those machines tiny, and the factories to match. Wnt (talk) 12:46, 17 February 2017 (UTC)[reply]

February 17

Plant from Bangladesh

Which plant is farmed here? I've never seen such fruits.--Sascha GPD (talk) 13:45, 17 February 2017 (UTC)[reply]

Hard to tell. The fruit resembles durian or maybe jackfruit or maybe breadfruit. --Jayron 32 14:22, 17 February 2017 (UTC)[reply]

Amongst other things, the leaves look wrong for all 3 of these to me. Nil Einne (talk) 15:01, 17 February 2017 (UTC)[reply]

Doing more google searches, other spiky green fruits include guyabano, or some species of cucumber, such as a luffa or Marah (plant) (aka manroot). --Jayron 32 16:37, 17 February 2017 (UTC)[reply]

I'll admit the first thing I did was take a quick look at the breadfruit article... then I realized this would be hard. I suck at botany, but my notion is that the first thing you do is fire up the glossary of leaf morphology and open the image to full resolution. At center-right far-top there's a little clearing and you can see the leaf beneath it, and various others, have branching leaf veins and jagged edges, with the veins apparently running to the narrowest parts of the edges. So I would say these are simple leaves (our redirect just takes you to leaf). The margin I would call "dentate" rather than "serrated" because the "teeth" seem symmetrical, and not "crenate" because they seem roughly zigzag. I think the shape of the leaf is "heart-shaped" = "cordate" - not to be confused with a chordate! In places the vein branching matches our figure for "dichomatous", in others "palmate" - I'll let someone else take a bite at that apple. And while the perspective confuses me a bit, I think I can see there are long stems supported on a framework that have leaves branching "alternately" in each direction, toward and away from us. So I am going to suggest that additional searches include dentate cordate alternate ... and I'll hope for a miracle. ;) Wnt (talk) 19:35, 17 February 2017 (UTC)[reply]

I should mention I did have a look at various other Artocarpus, none of them seem to have similar leaves. So perhaps either a speciesly less commonly cultivated or somethign else. Nil Einne (talk) 03:24, 18 February 2017 (UTC)[reply]

My guess is some member of the family Cucurbitaceae, superficially it resembles Echinocystis lobata but it seems that species is not cultivated. Most likely it is of the genus Cucumis (same as cucumbers) Cucumis zeyheri has similar morphology but appears to grow on the ground rather than as a climbing vine. Hope this helps. 204.28.125.102 (talk) 00:31, 18 February 2017 (UTC)[reply]

Is abstract thinking unique to Homo sapiens?

--IEditEncyclopedia (talk) 14:19, 17 February 2017 (UTC)[reply]

Wikipedia has an article on Animal cognition which would be a good starting point for your research. --Jayron 32 14:24, 17 February 2017 (UTC)[reply]

Is there non-circle Neanderthal geometric art? Like squares or triangles? If there isn't then maybe yes. Or maybe not. Even were that 100% foolproof maybe there were millions of Neanderthals in all time and only one had abstract thought and we've just never found his drawings of cubes and icosahedrons. Sagittarian Milky Way (talk) 14:31, 17 February 2017 (UTC)[reply]

And what do you call a 1/8th homo sapiens who had the smarty genes from her homo sapiens great-grandparent and the ability to bench press hundreds of pounds from her 7 Neanderthal great-grandparents? Sagittarian Milky Way (talk) 14:45, 17 February 2017 (UTC)[reply]

Apparently John Urschel ;-). --Stephan Schulz (talk) 15:56, 17 February 2017 (UTC)[reply]

It would be difficult to test for animals fully understanding abstract thought, so we might do better to test for their understanding of things like scale models first. For example, show them a scale model of a room with a treat hanging out of a box, then take them to the full-sized room and see if they check out the full-sized box first (don't actually put a treat in it or they might smell it). If they don't understand scale models, there doesn't seem to be much hope for them understanding more complex abstract concepts. StuRat (talk) 16:33, 17 February 2017 (UTC)[reply]

Yes, it is difficult, but a cursory search shows that a number of scientists have designed a range of test for assessing abstraction on non-humans, and then published the results in peer-reviewed studies. Science is often difficult, but that is no reason things can't be studied and understood. I wonder- how long did you look for references on this? SemanticMantis (talk) 18:33, 17 February 2017 (UTC)[reply]

If you can find animals that can handle scale models, then the next step is to make it a scale model, except that it's a mirror image, and see if they can handle that, then start changing details, like make it a different type of chair and box in the room. Then perhaps try a photo of the room, then a map. At this point, we are getting into fully abstract thought, or we can identify precisely where each animal falls short. StuRat (talk) 22:23, 17 February 2017 (UTC)[reply]

This being the science desk, I don't think abstract thought has a definition sufficiently precise to qualify for use in the question posed, which is Is abstract thinking unique to Homo sapiens? Bus stop (talk) 17:06, 17 February 2017 (UTC)[reply]

There are certain terms which have more precise meaning in psychology and philosophy which may be more precise, such as metacognition and theory of mind. We even have an article titled Theory of mind in animals and Animal consciousness, although both of those suffer from the same issues as human definitions as noted in hard problem of consciousness. --Jayron 32 18:24, 17 February 2017 (UTC)[reply]

No. Not according to some definitions and some research. See e.g. Visual categorization: accessing abstraction in non-human primates [26] and A non-human primate test of abstraction and set shifting: An automated adaptation of the Wisconsin Card Sorting Test [27]. Both articles are freely accessible, you can look at the prior work they cite, and you can use google scholar to look at other articles that cite these works. SemanticMantis (talk) 18:32, 17 February 2017 (UTC)[reply]

First of all, I'm not entirely sure that I use the term "abstract thought" in the same way that others do here, so forgive me if I go off on a tangent. There were some famous observations by Wolfgang Kohler which may be relevant here. Kohler had a large enclosure containing several chimps. There was a bunch of bannanas hanging very high in the enclosure, and on the ground there were various items, including several crates and sticks. The story goes that one day, a chimp piled 3 crates on top of each other (without trying to get the bannanas between stacking crates). After the third crate had been stacked, the chimp grabbed a stick,climbed the crates, and reached up with the stick to get the fruit. One account of this is here[28]. There are a couple of other terms used in this area of ethology which might be helpful for research. These include "gestalt" or "gestalt thinking", or the Eureka moment. DrChrissy ^(talk) 18:58, 17 February 2017 (UTC)[reply]

I wouldn't call that abstract thought, it's tool use. Visualizing how to stack the boxes is not abstract, but rather a concrete thought process. Similarly, crows use tools [29], and any bird building a nest or perhaps spider building a web is using similar concrete thought processes. StuRat (talk) 19:08, 17 February 2017 (UTC)[reply]

Oh yes, it could be classified as tool use - it could be placed in several other categories of behaviour - perhaps cognitive trial-and-error. What do you mean by a "concrete thought process" - this is not an ethological term I have encountered before. DrChrissy ^(talk) 19:20, 17 February 2017 (UTC)[reply]

side conversation, no references, open at your own time-wasting peril SemanticMantis (talk) 23:40, 17 February 2017 (UTC)[reply]

Perhaps tangible is a better word for it then. I mean thought processes which can be visualized physically, like the stacking of blocks, as opposed to an abstract concept like "honor", which can't be. StuRat (talk) 22:20, 17 February 2017 (UTC)[reply]

But this is now becoming circular. You are using words which can not be defined for non-human animals, such as "honour". If we can't define it, or at least develop a working definition, we can't test it. DrChrissy ^(talk) 22:34, 17 February 2017 (UTC)[reply]

This is part of the problem. It's difficult to even define what abstract thought in animals would be, much less test for it. But it's not being able to visualize how to stack blocks. From what we know about humans with no language skills (who later developed them so they could describe what it was like before, like Helen Keller), they thought in terms of pictures, making abstract thought an impossibility. If animals also think this way, then they would have similar limitations. Of course, animals do have some language skills, but they seem to be rather rudimentary. StuRat (talk) 22:57, 17 February 2017 (UTC)[reply]

I'm sorry but this is going off on tangents which have nothing to do with the OP. You are throwing in terms such as "tangible", "concrete", "visualise" with no definition and in ways that simply do not relate to my understanding of ethology. This is really not helping the reader. DrChrissy ^(talk) 23:12, 17 February 2017 (UTC)[reply]

@StuRat:. Why don't you try reading a bit about the topic? I have given two very relevant references, each of which contains working definitions of abstraction, and each of which cites many additional scholarly works. The ones I posted are freely accessible, but some of the works they cite are not. If you would like to read some of them and do not have access, just let me know, and I will be happy to provide copies if I can. This is not a desk for you to approach a field from an ignorant position, and hope to work things out from first principles. This is a reference desk, where our goal is to serve our patrons with references. Since you clearly don't know much about this topic, and cannot (or will not?) supply any suitable references, try reading some of the references provided - try to learn from the experts, rather than stumbling around the topic like a chihuahua in a sock. SemanticMantis (talk) 23:39, 17 February 2017 (UTC)[reply]

Hopefully this def of abstract thought, which contrasts it with concrete thought, will help you understand the difference better and will help us define, and hence answer, the OP's Q: [30]. StuRat (talk) 23:39, 17 February 2017 (UTC)[reply]

Spider and snake

About this video: http://videos.elmundo.es/v/0_ynih8y9m-esta-arana-acaba-con-una-serpiente-10-veces-mas-grande?uetv_pl=virales&count=1 What kind of spider is this and what is she planning to do with the snake, eat it somehow?? Thanks, --ZygonLieutenant (talk) 16:39, 17 February 2017 (UTC)[reply]

I tried three times on two different browsers, and got a "connection error" on the video every time. If you can find another copy of the video hosted elsewhere, or can tell us where it originally appeared, that might help.

However, there's a decent chance you saw this video [31] of an Australian redback spider attacking a snake, though the version I link ends before the snake is clearly dead. The video clip is understandably very popular, and has been shooting all around the internet the past few days, so I think that might be what you saw. SemanticMantis (talk) 19:36, 17 February 2017 (UTC)[reply]

_{Ummm yes it's the same video and it's faked. Blooteuth (talk) 19:03, 17 February 2017 (UTC)}[reply]

Is that your opinion, or do you have some reference to support the claim? Are you claiming it's not a spider? Or not a redback spider Or not a snake? Or that it is a spider and a snake but the spider is not at Can you explain what you mean by that, and give references if possible? Also, you have interjected you comment in the middle of my post, in violation of WP:THREAD. Please follow our guidelines, they help us keep things intelligible and organized here. Rather than move all the related comments around, I will simply sign again above, but please don't make extra work for us. SemanticMantis (talk) 19:08, 17 February 2017 (UTC)[reply]

I was just about to reply supporting Blooteuth. My opinion, and it is only opinion, is that the video is likely to be faked. I lived in Australia for 12 years and have plenty of experience of red-backs. The one in the video looks absolutely ENORMOUS. Our Redback spider states "Females have a body length of about 10 millimetres (0.4 in), while the male is much smaller, being only 3–4 mm (0.12–0.16 in) long." The beast in the video looks very much larger than this. DrChrissy ^(talk) 19:15, 17 February 2017 (UTC) [reply]

I have no strong opinion on this specific video, but have no problem believing such a thing could happen, given the descriptions in the ref I just posted below. I agree the spider looks a bit bigger than 10mm, but the angles are odd, and there is considerable variance in female size [32] SemanticMantis (talk) 19:18, 17 February 2017 (UTC)[reply]

Oh, I agree this behaviour could happen, I'm just not sure about this particular video. It's a shame there were not more objects in the background to help judge size and perspective. Or better still, a person in a white lab coat placing a ruler by the side of the spider, perhaps with a running commentary about how many of her mates she had eaten in the last month! ;-) DrChrissy ^(talk) 19:52, 17 February 2017 (UTC)[reply]

As for the second question: some spiders can and do eat snakes sometimes. The spider venom of some species can act to essentially liquify the interior of prey, letting the spider suck out all it wants (some additional info here [33]). See here [34] for a similar example. SemanticMantis (talk) 18:18, 17 February 2017 (UTC)[reply]

re the Daily Mail story: I'm not sure I have heard of red-backs throwing their web at potential prey. I know some spiders hunt a little like this (see bolas spider) but I always thought the red-back was a sit-and-wait character. DrChrissy ^(talk) 19:07, 17 February 2017 (UTC)[reply]

Yeah, I wouldn't vouch for anything the DM says with respect to biology. However, this review article [35] says, with additional reference "Latrodectus hasselti spiders enjoy a varied diet, trapping some 60-70% of beetles as well as other kinds of insects, spiders, small mice and occasionally lizards which blunder into their sticky trap lines." It continues to describe how the spider incapacitates prey by "squirting a swathe of viscous silk over its target." The article does not specifically describe snakes being caught in this manner, but to me, it's not hard to believe that a spider that can catch lizards can also catch a small or even (perhaps rarely) medium-sized snake. SemanticMantis (talk) 19:17, 17 February 2017 (UTC)[reply]

Great reference - thanks very much. DrChrissy ^(talk) 19:25, 17 February 2017 (UTC)[reply]

The video got an article on National Geographic's website. [36] 209.149.113.5 (talk) 19:50, 17 February 2017 (UTC)[reply]

Thanks! They don't seem very skeptical... SemanticMantis (talk) 20:17, 17 February 2017 (UTC)[reply]

Looks like there's a fishhook holding the snake in place. Justin15w (talk) 20:12, 17 February 2017 (UTC)[reply]

What is the difference between IS:733 and IS:736

Dear all, Kindly clarify what is the difference between aluminum alloy standards as mentioned in Indian standards Is:733 and Is:736. for example i am giving manufacturing drawing for a milled box sizing 60x60x40 mm. Should i mention material to be as per IS:733 or IS:736. Ex: 1.Material:Aluminium alloy To IS:(733 or 736),Grade:64430-T6 Please clarify SD