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April 27[edit]

Increase in mean sea level pressure due to global warming[edit]

I was wondering if this has been measured. This increase is easy to compute. If we put the original value equal to P = 101325 Pa, then if the CO2 concentration increases by an amount x, the pressure should increase approximately by x P m_C/m_at where m_C is molecular mass of carbon = approximately 12 u and m_at = average molecular mass of the atmosphere = approximately (0.8*32 + 0.2*28) u = 31.2 u. An increase from 0.03% to 0.04% of the CO2 concentration should thus have increased the pressure by about 3.9 Pa.

Around 15 C, the vapor pressure increases at about 110 Pa/K. This means that at about 60% relative humidity, a 0.8 C rise in temperature should have contributed to about 53 Pa increase in pressure, so the total pressure increase is about 57 Pa. This makes the current mean sea level pressure equal to about 101382 Pa, which corresponds to a fictitious barometric height difference of 4.4 meters. Count Iblis (talk) 01:02, 27 April 2014 (UTC)[reply]

That's such a small percentage that it would easily be swamped by normal pressure changes due to storms, etc. So, you'd need to average over a long time period to detect any average change. StuRat (talk) 02:49, 27 April 2014 (UTC)[reply]

Yes, you would expect the standard deviation to be a 100 times larger, this means that you would need about 10,000 independent observations. If air pressure fluctuations are correleted on a typical time scale of a week, then with 100 well separated observation stations, you would need to average the data taken over a two years period. So, it seems to me that it is possible to detect this effect. Count Iblis (talk) 15:20, 27 April 2014 (UTC)[reply]

The definition of "independent measurements" is important here. Since some storms, like hurricanes/typhoons, persist over wide areas and more than a week, they would presumably affect multiple air pressure readings under your schedule. StuRat (talk) 15:31, 27 April 2014 (UTC)[reply]

Another effect is the decrease in the gravitational acceleration at the Earth's surface. The air pressure increase corresponds to there being about 3*10^15 kg of mass more in the atmosphere, which should decrease the gravitational acceleration at the Earth's surface by about 4.9*10^(-9) m/s^2. This decrease of 0.5 ppb is only about 5 times smaller than the standard error of state of the art gravimeters, so it sould be easily detectable with multiple measurements. Count Iblis (talk) 15:20, 27 April 2014 (UTC)[reply]

However, we don't have a good measurement of this when the global temperature was 0.8 C lower than present, but we should be able to measure the decrease in the gravitaional acceleration over the next few decades. Count Iblis (talk) 15:30, 27 April 2014 (UTC)[reply]

There could also be other effects to counter an atmospheric pressure increase. For example, more "air" might well push the atmosphere outwards farther from the Earth's surface, where more of it is lost to space. StuRat (talk) 15:35, 27 April 2014 (UTC)[reply]

You seem to be switching around rather cavalierly between concentrations of CO_2 and mean annual global temperature changes. Of course these are linked, but not in any clear and simple fashion. So, careful with your reasoning there. The seasonal swings in CO_2 are also rather large, and the amplitude of that cycle is also increasing, see e.g. here [1], and here [2]. SemanticMantis (talk) 15:42, 27 April 2014 (UTC)[reply]

This paper isn't exactly what you're talking about, but it does discuss using pressure as an indicator of climate change [3]. You might be able to track the cited literature, or see who has cited this work more recently. SemanticMantis (talk) 15:46, 27 April 2014 (UTC)[reply]

Pressure may be affected by more than CO₂ mass in the atmosphere. Any other variations components of the atmosphere would similarly contribute, and would have to be corrected for. I'm thinking here primarily of the total H₂O content of the air, which potentially could vary significantly, e.g. with climate change: an increase of temperature might lead to an increase of H₂O vapour globally, which would contribute to the pressure increase. An increase of pressure could not then be ascribed wholly to CO₂. Another factor that must be taken into account is the change in total O₂: most CO₂ would be associated with a removal of O₂. I see that this balance has been assumed in Count Iblis's initial calculations, but we'd need to consider how exact this is. For example, there are processes that add and remove CO₂ without a commensurate change in O₂, such as volcanic activity and calcium carbonate precipitation in the ocean. —Quondum 17:47, 27 April 2014 (UTC)[reply]

This paper states that the removal of carbon dioxide (and therefore, indirectly, oxygen) by the oceans makes the change of dry air pressure less than 1 Pa, and also says it's likely negative. By the way, the initial calculation of mean molecular mass should have been (0.8*28 + 0.2*32) = 28.8, or more accurately (0.78*28 + 0.21*32 + 0.009*40) = 28.9. Icek (talk) 19:30, 27 April 2014 (UTC)[reply]

Thanks everyone for your comments! Count Iblis (talk) 21:00, 28 April 2014 (UTC)[reply]

Liquid and Gas SiO2 ???!!!...[edit]

What is the lowest pressure and the temperature range in which the SiO₂ is Liquid and Gas:

O=Si=O pressure=… temperature from…. to…. = Liquid temperature from…. to…. = Gas

THANK you

SPYROU Kosta - Greece--85.74.189.98 (talk) 03:43, 27 April 2014 (UTC)[reply]

The article Silicon dioxide says the melting point is 1600 to 1725 C and the boiling point is 2230 C. 24.5.122.13 (talk) 03:51, 27 April 2014 (UTC)[reply]

Cristobalite, the high temperature modification of SiO₂, melts at 1986 K (1713 °C), and I don't know why the article Silicon dioxide gives such a large range (maybe someone wrote it using a source about various impure forms of SiO₂, and impurities will certainly change the melting point).

But 85.74.189.98 is more or less asking about the triple point of silicon dioxide. I don't know it, but I guess the triple point temperature isn't much below 1986 K.

As for the lowest temperature at which SiO₂ is a gas, you have to know that in thermal equilibrium at 0 pressure everything is a gas (even if sublimation is often very very slow). So it can in principle be a gas at any temperature, if the pressure is low enough. Whether you can measure it as a gas depends on instruments and experimental procedures.

Icek (talk) 19:11, 27 April 2014 (UTC)[reply]

Amitriptyline[edit]

What are its effects on the body? Does it have a sedative/anaesthetic property like sleeping pills? Does it help make muscles relaxed and reduce (or block) stress/pain signals like the stuff they give you before surgery? Money is tight (talk) 06:36, 27 April 2014 (UTC)[reply]

Amitriptyline is our article on the subject. If someone has additional information with a WP:MEDRS-compliant source, please add it there. DMacks (talk) 07:19, 27 April 2014 (UTC)[reply]

Yea I've read the article, it doesn't go into detail nor mention anything about what I asked. If any expert knows please tell me. — Preceding unsigned comment added by Money is tight (talk • contribs) 10:30, 27 April 2014 (UTC)[reply]

Since amitriptyline is a tricyclic antidepressant (which is linked in the first sentence of the article), you might look at that article, which has some information about analgesic properties, etc. Deor (talk) 12:15, 27 April 2014 (UTC)[reply]

Right. It's mainly used as an antidepressant and would not have substantial sedative effects on most people. See Tricyclic antidepressant#Side effects for a list of other effects. Looie496 (talk) 19:00, 27 April 2014 (UTC)[reply]

Amitriptyline is a favorite and traditional analgesic as used by primary care physicians. It is fairly sedating and used as such in practice. It is a rather dangerous drug in overdose as well (all tricyclics are). --AboutFace 22 (talk) 23:29, 27 April 2014 (UTC)[reply]

In overdose the drug can depress the CNS as an antihistamine antagonizing the Histamine H1 receptor - see [4]. This is among a huge list of other effects such as causing cardiac arrest and delayed seizures. There was a meta-analysis on its use in treating insomnia at [5] but I haven't read the paper; the abstract suggests tolerance develops pretty quickly that reduces antihistamines' effectiveness in inducing sleep. [6] calls it a "sedating antidepressant". [7] classes it as a sedative/hypnotic drug with low abuse potential. Wnt (talk) 17:00, 28 April 2014 (UTC)[reply]

Solar tax[edit]

Is there more information on Wikipedia about this piece about solar tax? 87.78.128.11 (talk) 07:19, 27 April 2014 (UTC)[reply]

You mean like Political activities of the Koch brothers? Bear in mind that Wikipedia is not the news.--Shantavira|^{feed me} 09:23, 27 April 2014 (UTC)[reply]

You can also inform yourself about the technical parts of this issue by reading about net metering; billing an energy customer for their net use, or, the quantity of energy delivered by the grid, minus the quantity of solar energy produced on site. Nimur (talk) 13:45, 27 April 2014 (UTC)[reply]

Sticking out your tongue while doing complicated tasks[edit]

Mostly seen in children: sticking out your tongue while doing a complicated task, like coloring between the lines (or playing a violin). Google gives me a wide range of explanations of which "sticking out your tongue reduces the amount of stimuli sent to your brain" sounds reasonable. But then again, besides while eating, my tongue probably sends messages like "yep, still 37 C", "nothing to see here". Taking of your shoes would reduce the amount of messages a lot more. I'd expect a much more direct reason, like where the part of the brain that takes care of complicated stuff has a direct connection to the nerves connected to the tongue. Joepnl (talk) 17:01, 27 April 2014 (UTC)[reply]

Tongue protrusion is one of the earliest behaviors shown by newborn babies. I'm just speculating, but possibly it is a reflex that escapes from inhibition when children are concentrating intensely. I don't recall ever seeing this myself, though, so I wonder how common it really is. Looie496 (talk) 19:36, 27 April 2014 (UTC)[reply]

Maybe you're too young to remember Michael Jordan? ←Baseball Bugs ^{What's up, Doc?} carrots→ 20:18, 27 April 2014 (UTC)[reply]

I'm older than Michael Jordan, but I'm not a Pro Basketball fan and don't know what you're talking about. Looie496 (talk) 21:43, 27 April 2014 (UTC)[reply]

Google Image "Michael Jordan tongue" and you'll see many examples. ←Baseball Bugs ^{What's up, Doc?} carrots→ 23:04, 27 April 2014 (UTC)[reply]

@Looie496: Google for "tongue concentration" and click images. That must look familiar. Joepnl (talk) 21:41, 27 April 2014 (UTC)[reply]

Sticking one's tongue out while concentrating is a recurring theme in classic cartoons. ←Baseball Bugs ^{What's up, Doc?} carrots→ 23:13, 27 April 2014 (UTC)[reply]

Yes, it's a nice visual way to convey "concentrating hard" in a single frame. StuRat (talk) 17:35, 28 April 2014 (UTC)[reply]

Children learning to print letters of the alphabet sometimes stick out there tongues and make small tongue movements not unlike the motion of the pencil. It was funny therefore to observe freshman college students in a psychology lab experiment where they had to look at a star pattern they could only see in a mirror while tracing it with a crayon. Left to right movements have to be the reverse of when they look like. Some of them had their tongues out to somehow aid in the perceptual-motor class, and they laughed when they noticed it, remembering the behavior in kindergarten or first grade and how they had been told back then not to do it. The mirror-drawing task would be a great way to elicit the tongue-sticking-out behavior in adults. I recall people doing the "tongue sticking out" as well while learning to tie a complicated knot. Maybe its just by-play or maybe it helps somehow in doing a new perceptual-motor task. Edison (talk) 19:47, 28 April 2014 (UTC)[reply]

How much COLORS in the RAINBOW do see:... (???)[edit]

Humans and Primates with three(3) Color-Vision see: 3+3+1 = 7 Colors in the Rainbow...

Animals(Mammals) with two(2) Color-Vision see: 2+1 = 3 Colors in the Rainbow???...

Animals(Birds,Reptiles) with four(4) Color-Vision see: 4+4+4+1 = 13 Colors in the Rainbow???...

The "Mantis-Scrimp" with twelve(12)Color-Vision see: (11*12)+1 = 133 Colors in the Rainbow???...

THANK you VERY-VERY much!!!

and... "Have a nice Day/Night !!!..."

SPYROU Kosta - Greece — Preceding unsigned comment added by Honeycomp (talk • contribs) 22:21, 27 April 2014 (UTC)[reply]

The number of colours we divide the rainbow into is not a physical absolute - it's culturally determined, and the common preference for the number 7 shows itself here. There's no direct connection between that and how our eyes work in reality. AlexTiefling (talk) 23:04, 27 April 2014 (UTC)[reply]

(ec) The article Color vision includes a section about non-human species. Various animals are believed to have monochromatic, dichromatic, trichromatic (the human norm), tetrachromatic or even perhaps pentachromatic color vision, based on the kinds of color recepters in their retinae. We may agree on a set of names for the colors our eyes perceive but that is a subjective process with no obvious limit to how many categories our essentially continuous (analog) sensation has. This article discusses the arbitrariness of our color names. The article Rainbow mentions that a human eye can distinguish in the order of 100 colors in a rainbow spectrum. However this number is not reflected in any language and usually just 7 names suffice: Red, Orange, Yellow, Green, Blue, Indigo, Violet. It is not objectively correct to say any finite number of colors exist in the visible spectrum because it is a (small part of) a continuous range of electromagnetic radiation frequency, nor are colors we see limited to the spectral colors: in addition we see de-saturated (i.e. mixed with white) and impure (mixtures such as red+blue) colors. 84.209.89.214 (talk) 23:14, 27 April 2014 (UTC)[reply]

Back in my day there were six - red, orange, yellow, blue, green, and violet. Now they say seven. Bubba73 ^{You talkin' to me?} 23:16, 27 April 2014 (UTC)[reply]

Green has always lain between yellow and blue. 84.209.89.214 (talk) 23:26, 27 April 2014 (UTC)[reply]

The divisions are (of course) completely arbitrary. But, yeah - I was always taught Red/Orange/Yellow/Green/Blue/Indigo/Violet. That doesn't mean that there are no other names..."Cyan", for example, is a color intermediate between green and blue which is clearly visible in a spectrum ("Sky blue" is perhaps a more common name). But some cultures have no separate names for green and blue - check out our article on Distinction of blue and green in various languages. In computer graphics, we talk about the color "Magenta" - which is a mixture of red and blue light. Technically, that doesn't appear in the spectrum because it's a mixture of colors - but it's visually similar to "Violet".

Color is a subtle business. If you click on the image at right here until you're seeing it at the full size - it contains every single color that a computer screen can display. If you continue to zoom in until the original pixels in the image are big enough to cover a good area of your screen, you'll find that in some areas you can see the difference between adjacent colors - which means that you could have seen a color midway between the two. But in other areas, you can't tell the difference between adjacent pixels - even though they are different colors as far as your computer display is concerned. But even that isn't a complete description of what we can see because there are colors that computer screens and TV's can't display...getting a really good "cherry red" on a computer screen is completely impossible.

Our perception of color is messy - everything depends on the brightness of the image - the color of the background around it - how bright the room lighting is - how tired you are...many, many things. So I don't think we have a good answer for "the number of colors we can see".

What our OP is asking is a bit confused. Humans can see three "primary colors" (red, green, blue) and we can perceive three "secondary colors" (cyan, magenta, yellow) and one tertiary color (white). But we know that we see other colors like brown, orange, pink, grey that aren't primary, secondary or tertiary. There is at least one human who can see four primary colors (see: Tetrachromat). She can (presumably) also see seven secondary colors, four tertiary colors and one quaternary color (white)!

SteveBaker (talk) 23:46, 27 April 2014 (UTC)[reply]

No, normal color vision is based on four psychological primary colors, or six if you count white and black. It's hard to know how tetrachromacy would change that. Anyone with normal color vision can become a tetrachromat—a hexachromat, actually—by holding a broad-spectrum color filter in front of one eye. Congenital tetrachromacy might be like that: certain colors might just look "odd" because the brain is getting conflicting signals. Or it might involve two completely new opponent colors with qualia never experienced by ordinary humans (but it seems unlikely that the visual system is that flexible). I think no one knows. -- BenRG (talk) 04:09, 28 April 2014 (UTC)[reply]

According to Indigo#Classification as a spectral color, Isaac Newton added indigo to the spectrum because for mystical reasons he thought that there ought to be as many colors in the rainbow as notes in the major scale. Given that origin, it's pretty silly that we still teach the seven-color rainbow in grade school. -- BenRG (talk) 04:09, 28 April 2014 (UTC)[reply]

Normalized response spectra of human cones, S, M, and L types, to monochromatic spectral stimuli, with wavelength given in nanometers.

To explain how our color vision works, look at this graph. That shows the relative strength of the signals coming from each of our 3 color receptors, based on the color. By comparing the signals returned by each of the types of receptors, our brains can determine which color it is. We could even live without the middle receptor, and still determine all the colors of the rainbow, if our brains were set up to use that input. All that we would lose is a bit of fine color resolution between green and red. Similarly, adding more receptor types wouldn't help us see more colors, unless they are further in the infrared or ultraviolet range. They would help us to distinguish close wavelengths more precisely, though. As you can see, those colors between the M and S receptors don't seem to change as much as between the M and L receptors, because those receptors are more widely spaced. If we had a receptor between M and S, say called the "M-S receptor", then we would presumably see more color differences in that range. StuRat (talk) 00:04, 28 April 2014 (UTC)[reply]

Yes, you could "determine all the colors of the rainbow" with only two receptors, so long as the ratio of their responses were strictly monotonic. However, there are colors not in the rainbow: magenta is the most obvious choice, being a mixture from the two ends. With only two receptors you cannot distinguish a magenta that (say) stimulates both receptors equally from some shade of green that also stimulates them equally, or from (an approximate) white that is the sum of the two. (White is also not a spectral color, of course.) Conversely, adding more receptors does let you see more of these non-spectral colors. --Tardis (talk) 07:09, 29 April 2014 (UTC)[reply]

SPYROU Kosta: Hi...I unterstand that in the Rainbow Colors someone can see more or less colors from seven(7)... The only think you need is to give Names to the different shades of Colors!!!...

BUT it has to be a Mathematical and Physical FORMULA like:

2 colors A,B : {A},{AB},{B} = 3

3 colors A,B,C : {A},{B},{C},{AB},{AC},{BC},{ABC} = 7

The Eye has the (inner) and the outer Circle: (Red) + anti-red, (Green) + anti-green, (Blue) + anti-blue...

It must to be a way to calculate the Colors-Vision... (You cannot ask your cat-dog-bird how much Colors can they see!!!...)

THANK you and have a nice Day/Night

SPYROU Kosta - Greece - Honeycomp (talk) 02:39, 29 April 2014 (UTC)[reply]

Colors are not finite things, there are an infinite number of colors in the rainbow, each with a slightly different frequency. You can come up with as many colors names and numbers as you would like, even without blending different frequencies of light together. So, how many colors we can see is all a matter of opinion. Now, there is what color resolution you can see, and more color receptors should increase that, but the number of color gradients we can see is in the thousands.

The mistake you are making is thinking that all color receptors of a given type either fire at full strength or don't fire at all, for a given color. They can also fire at reduced strength or only some can fire. To represent this mathematically, perhaps we can use binary: If you have only two receptor types, and one has a value of "1", while the other has a value of "2", you might think you could only get values of 0, 1, 2, or 3 out of the total of the pair. But the first receptor type can actually have a range of values from 0.01 to 0.99 between 0 and 1, and the second receptor similarly has a range. And it's not just the sum that's significant, as our vision brain cells can distinguish which signal comes from which receptor type.

So, vectors might be the way to represent the range of inputs to our brain. For example, a brain cell might get 0.87G + 0.93B + 0.02R, and conclude that the color is cyan. In this model, with 100 gradients detectable for each receptor type, and 3 receptor types, we get 100³ or a million possible colors. Our vision works something like that. You might think that with only two receptor types, than such an animal would only have 100² or 10,000 colors, but they might also have more gradients they can detect at each receptor. If they can detect a thousand gradients, instead of 100, then we are back to 1000² or a million colors they can detect. StuRat (talk) 19:11, 29 April 2014 (UTC)[reply]

Yes, but because most colors are combinations of frequencies, someone with only a red and a blue receptor would be unable to tell the difference between (say) green and magenta! Green light would stimulate both the red and blue receptors to some degree - and so would magenta light. It doesn't matter how sensitive those to receptors are - fundamentally, someone with no green detectors is color-blind and cannot perceive as many color differences as someone with three functional detectors. That's why tetrachromats are able to see more distinct colors than us trichromats. Someone who happened to have a detector for pure yellow light would see the color emitted by a sodium lamp to be a totally different color than the yellow emitted by a computer screen displaying a picture of a sodium lamp. The latter would have both red and green light - but no yellow...so it would look completely different. There is a question of whether a human tetrachromat would develop the necessary brain function to make use of that extra capability - but the study of that lady in the UK who is a tetrachromat proves that (at least in her case) it's perfectly possible. SteveBaker (talk) 19:59, 29 April 2014 (UTC)[reply]

Interesting, do you have any links for that woman ? StuRat (talk) 02:12, 30 April 2014 (UTC)[reply]

The researcher who tracked her down refuses to give her name - she's known in the literature as "subject cDa29" - if you google for that phrase, you'll find a bunch of information about her. I believe she was found as a result of a prediction that a very specific history of parental and grandparent colorblindness and a female subject would (at some probability) yield a tetrachromat - so they tracked down people with that history and tested them. This specific woman was (I believe) the only one they found. SteveBaker (talk) 02:45, 30 April 2014 (UTC)[reply]

SPYROU Kosta: THANK you SteveBaker for your Help!!!...Honeycomp (talk) 23:11, 29 April 2014 (UTC)[reply]

SteveBaker made three mistakes. 1) As pointed out by StuRat, the retinal sensing is not binary (on/off), it's graduated. 2) SteveBaker seems to think that all "red" cones have their sensitivity peak at the exact same red wavelength, all "green" peak at the exact same green wavelength, all "blue's" on the exact same blue. That's not correct. In each nominal colour, diferent cones in the same eye peak at AROUND a similar wavelength. That's why you can see more colours than can be reproduced in a three-colour TV display, or even 4-colour printing, though the difference for people with normal colour vision is somewhat subtle. 3) He's not realised that the response of each retinal sensor is not linear - its logarithmic, just like every other sensory system in the animal kingdom, e.g., hearing. As is well known amongst audiologists, to make a sound percieved as twice as loud, you need about 10 times the power, not twice. Same with the light sensisivity of the retina, and the brain can utilise the improved response to weak colours. It means, for example, that the response of "blue" sensors is not just high sensitivity to blue, a bit to green, and none at all to red. The response, which varies for sensor to sensor, is maximum to blue, quite a bit to green, and weakly to red.

All this means is that you do not get people who are missing (say) green cones and cannot see green at all, or cannot distinguish between different greens. They can, but to reduced degree. Some to greater degree than others.

Note that individual cones are not wired to the brain. They are wired together in groups, each group sending an agregate signal to the brain. This improves tonal graduation and low light sensitivity at the expense of resolution. It's why I have used the term "sensor" above, because a more smooth logarithmic response to light level is constructed in the aggregation from what an engineer would regard as inputs from noisy erratic pickup in the cones.

All this means that people can see an immense range of colours, even if only two types of cones are present, and even quite a range of colours if only one type of cone is present.

SteveBaker is also wrong about not being able to get a good cherry red on TV displays, however this is a common misconception among graphic artists. It came about because in the early days of colour TV, RCA in America was able to make a very good red phosphor for their TV tubes. America and Europe then, very early, standardised the pigment colours for TV cameras and TV tubes on the RCA standards. However, the Japanese, who did everything they could think of to minimise paying royalties on RCA (and Philips) patents, standardised on a slightly brownish red phosphour. Almost all people do not notice the difference, but I used to work in TV repair, and if you adjust a Japanese TV set right beside a European set (using either a Philips tube or a licenced RCA tube), you can clearly see the difference, and you can't get as good a red on the Japanese set. The trouble is, by the 1980's, there was only Japanese picture tubes (made in Japan or Taiwan); RCA and Philips had become uncompetitive. High quality displays with a very good red capability remained available for non-television applications where it mattered, and it all changed when CRT displays were rendered obsolete by plasma and LED displays.

121.215.63.226 (talk) 02:02, 30 April 2014 (UTC)[reply]

Nice patent history lesson ! As for those animals with only one cone type, they would be able to detect how far a given color is from the peak for that cone, but couldn't tell on which side of the peak it falls. They'd also be confused by combination colors. StuRat (talk) 02:14, 30 April 2014 (UTC)[reply]

No, you've missed one of the points I made. For an animal with only one cone type, each cone will have its peak on a slightly different wavelength (colour). So, for any colour within the animal's good range, it CAN tell unambiguously what the colour is. The colour may be on one side of the peak for one particular cone (or aggregate of cones) in its retina, but nearby there will be other cones with their peaks on slightly different wavelengths/colours, and one or more of them will be on the same side of the peak of the first mentioned cone. It's quite different to the situation that you could have in a TV camera, where you could have a fault where two of the three colours are faulty or switched off - in such a case it is impossible to tell what the scene colours are, except in so far as how close the colours may be to the operating camera colour, as all the pixels of any of the three colours are the same. 121.221.220.128 (talk) 11:40, 30 April 2014 (UTC)[reply]

But in order for the brain to be able to distinguish whether colors are on one side of the peak or an equal distance on the other side of the peak, using another receptor with a different peak location, the brain would need to know on which side the secondary receptor's peak was offset. How would it know this ? And if it does know this, and is wired to use that info, how is this different from having an additional type of color receptor ?

In my own experience with cats, they seem to often miss food on the (different colored) floor, until I pick it up and hand feed it to them, so their color vision apparently isn't so good. StuRat (talk) 13:37, 30 April 2014 (UTC)[reply]

How would it know? When born, it will not. But it is well established, that despite a considerable degree of anatomic structure determined by genetics, the brain sorts out what means what by experience. This is why our sense of pain location is exquisitely good on the skin or within limbs, but pain from within the torso is quite unreliable. For example, a heart attack hurts, but the pain is often not from within the appropriate part of the chest - pain in the neck, jaw, or left arm is quite common. That's because when we are babies, there is plenty of instances of contact with the skin and impact with limbs to calibrate the sensory system, but a heart attack occurs for the first time typically in late middle age or later - no prior contact experience. The sensory system knows something is wrong, but not where.

So how will the brain know which cone peak means what colour? By experience. At first it only knows there something different about one colour versus another. How is this different to how the brain works with additional colour receptors? There is no difference.

When people who were born deaf with some middle ear problem are fitted with advanced cochlear implants, the macro structure of their nervous system gives them a sense of hearing - but it's all cockeyed. Often not much more than a lot of odd buzzes and high pitched whistles. But over a few months, experience puts things into place, and they hear low frequencies as low frequencies, buzzes as buzzes, and pure tones as pure tones, natural voices as natural voices. There was a famous experiment done in the 1950's - a volunteer wore spectacles with prisms that inverted his view of his environment. Up was down and down was up. After a few weeks, everything looked normal to him - his brain, based on experience, re-wired itself so to speak, to make things right again.

A friend of mine accidentally sawed off two fingers and the thumb of his hand with a circular saw. The doctors sewed one finger back on, but the other finger and the thumb was ruined and could not be put back. As a thumb is critical to holding and grasping all manner of things, the doctors cut off one of his big toes and with micro-surgery attached it back on where the thumb should be. They joined up the nerves more or less without regard of what nerve was for what. At first his finger and toe/thumb was numb. After a few weeks some feeling came back, but the location sensed was all wrong. After nearly a year, he says his sense of touch is completely normal, and correct as to location.

I don't know much about cats, but in general, mammals have only 2-colour vision. Humans are an exception to the rule. Birds have 4-colour vision - their extra "colour" is the ultraviolet, which we can't detect. I have performed a number of experiments with my german sheperd dog. He certainly has visual accuity comparable to human vision, but is unable to distinguish between different shades of green. I established this by placing about my yard small balls of different colours, and rewarding him when he brought one to me. But its' not quite as simple as it may seem. Being an inteligent, strong willed animal, he tries to train me as much as I train him. If he's bored with bringing back balls, he simply will not. And of course, for a dog, it matters not how good their sight is, if there is a smell about. It's much more fun to a dog to find things by smell. I grew up on a goat farm. The preference of goats to food handed to them over perfectly good food on the ground is marked - especially if no other goats are within sight. It has nothing to do with any limitation in their vision or any other sense. It is because they crave attention and affection.

121.221.220.128 (talk) 15:20, 30 April 2014 (UTC)[reply]

As far as fine-tuning the nerves on your skin, if it feels like a bug bit your palm, but you look at it and see it actually bit your thumb, then you have a secondary source of information to use to correct the primary source. What is the secondary source that will tell your brain whether a particular receptor has a peak on one side or the other of the average ? StuRat (talk) 16:36, 30 April 2014 (UTC)[reply]

I would have thought that obvious. The secondary source is not so much seeing the bug on your thumb, its seeing the bug is on your thumb and not your palm. Ever hurt a toe? We wear shoes and don't manipulate tools with our feet so toes are protected from contact much more than fingers. It's thus hard to know without looking which toe is hurt. Yet the nerve structure is much the same for fingers. Not as fine but the routing is similar. Look at an example: Let's say a person has only "green" receptors. A scene providing (say) 5530 nm (green) would produce strong excitation of cones centred very closely on 530 nm, and less strong excitation in cones peaking at 525 nm (a slightly blueish green) and similarly less strong excitation in cones peaking on 535 nm (a slightly brownish green). But a scene containing 535 nm light would result in strong excitation in the last mentioned cones, a slightly weaker response in the 530 nm cones, and a weaker again response in the 525 nm cones. So the brain gets a different input for 525 nm light, 530 nm light, and 535 nm light. A baby would just learn by experience that the three wavelengths are different, until he can talk and in discussion with others would learn what the colours should be called. Note this: the same person with only "green" cones, would if seeing light on 460 nm (blue) would get a different set of signals again - a weak response in the 525 nm cones, a slightly weaker again response in the 530 nm cones, and the 535 nam cones, an even weaker response again. However the difference in response levels would be a lot less than the differences with various green wavelengths. So, such a person can identify red light, and blue light, and know the difference, but not at all well compared to a person with normal eyes. Scenes of predominantly red and/or blue light would be registered by the eye as quite dark, however the brain has great facility for compensation. — Preceding unsigned comment added by 121.221.220.128 (talk) 08:51, 1 May 2014 (UTC)[reply]

Responding to 121.215.63.226/121.221.220.128 whose posts by content seem by the same person: SB did not make alleged mistakes nos. 1) or 3). SB also has colour theory on his side (this time) in pointing out that there are colors that computer screens and TV's can't display; these colours certainly include saturated spectral reds. Notwithstanding the debateable redness of cherries on TV, this is known to graphic artists. The implication of 121's claim that the brain gains colour discrimination at the expense of resolution by sensing groups of cones with fixed in-group patterns of unequal responses is that one should be able to stimulate different colour perceptions by changing the arrangement on a screen of a set of fixed pixel colours. That would be a significant development in Opponent process theory but has there ever been such an experimental validation? 84.209.89.214 (talk) 20:39, 30 April 2014 (UTC)[reply]

SPYROU Kosta: From the Book: "The First Steps in Seeing" by R.W.RODIECK - pages 218-219:

"Humans that lack functional L cones or M cones are also Dichromats. Rare human dichromats have this deficit in only one eye. To that eye, a rainbow appears BLUE in the INNER portion of the arc, fades to colorless toward the center, and progresses to YELLOW toward the OUTER edge of the rainbow..."

Kosta: {A}, {B} and White{AB} !!!...

So...my "Theory" has a point(.) !!!

THANK you for your Help - Honeycomp (talk) 00:26, 1 May 2014 (UTC)[reply]

Fullerene C24...Space-Filling Fullerite C24...are they only in THEORY???...[edit]

The Fullerene C24:

has the shape of the Truncated-Octahedron...with six(6) [Squares] and eight(8) <Hexagons>...

has 12 (C=C) Double Bonds and 24 (C-C) Simple Bonds.

The Fullerite C24:

has the shape of the Space-Filling Truncated-Octahedron...

has only Simple (C-C) Bonds...

Are they REAL or NOT???...

THANK you VERY-VERY much!!!

SPYROU Kosta - GreeceHoneycomp (talk) 22:35, 27 April 2014 (UTC)[reply]

It's my understanding that there are no stable fullerenes smaller than the classic C₆₀ structure, although the existence of cubanes shows that carbon bonds can be made to do much more unusual things. AlexTiefling (talk) 23:03, 27 April 2014 (UTC)[reply]

It seems my recollection was correct - in C₆₀, there are no squares, and no two adjacent pentagons. Either of those features would make a smaller shape unstable. C₂₄H₂₄, using the geometric shape you've described and no double bonds, would be a viable explosive, but there's no reason to make that shape rather than another. AlexTiefling (talk) 14:47, 28 April 2014 (UTC)[reply]

All unstable? That surprises me; I remember reading that someone had isolated C36, whose 15 hexa/penta forms include the two smallest where no three pentagons meet. —Tamfang (talk) 07:28, 29 April 2014 (UTC)[reply]

Interesting - if you can find a source, could it be added to our article on fullerenes? AlexTiefling (talk) 15:37, 30 April 2014 (UTC)[reply]

SPYROU Kosta: Why a Space-Filling "Cube(Rook)" of Truncated-Octahedrons-C24 would be EXPLOSIVE???... They are NOT H-Hydrogens in the inner Cube(Rook)!!!... They are only C-Atoms like the Diamond!!!... By the Diamond all the six(6) angles are 109,5^o... By the Space-Filling Truncated-Octahedron two(2) angles are 90^o

THANK you!!! Honeycomp (talk) 02:22, 29 April 2014 (UTC)[reply]

What do you mean by "rook" here? —Tamfang (talk) 07:28, 29 April 2014 (UTC)[reply]

SPYROU Kosta: SORRY I mean a stone: Rock !!! sorry!!!...I play to much Chess!!!...Honeycomp (talk) 14:02, 29 April 2014 (UTC)[reply]

It's my understanding that 90-degree bond angles are pretty unstable - this is part of the reason cubanes are so explosive. You're right that a C₂₄ with no hydrogens would probably be less combustible than one which had hydrogens, but that alone wouldn't make it stable. It might not explode, but it could readily decompose into an assortment of soot and shorter organic molecules.

One other thing that occurs to me, and this may be hogwash, because it's years since I studied this, but your proposed C₂₄ structure accounts for all the outer-shell electrons of every carbon atom. That rather implies that each molecule would have a very limited capacity to form electrical bonds with its neighbours, so I think it's comparatively unlikely that any theoretical close-packing would be maintained in practice. They'd behave a lot more like ball-bearings than like solid blocks. AlexTiefling (talk) 15:37, 30 April 2014 (UTC)[reply]

SPYROU Kosta: "THANK you very much AlexTiefling!!!..." Honeycomp (talk) 19:17, 30 April 2014 (UTC)[reply]

There is an Simple cubic fullerite C24: https://link.springer.com/article/10.1134/1.1649442 — Preceding unsigned comment added by 2a02:587:a008:d900:8d98:8d51:537d:4ba2 (talk) 21:10, 30 September 2017 (UTC)[reply]

Development Evolution-Tree of the 220 Human Cells???...[edit]

Humans have 200-220 diferend kind of Cells...

Is there a Development-Tree of them???...

THANK you VERY-VERY much!!!

"Have a nice Day/Night!!!..."

SPYROU Kosta - Greece - Honeycomp (talk) 23:01, 27 April 2014 (UTC)[reply]

In a developing embryo, stem cells differentiate into all the specialized cells—ectoderm, endoderm and mesoderm and thereafter maintain the normal turnover of regenerative organs, such as blood, skin, or intestinal tissues. 84.209.89.214 (talk) 23:23, 27 April 2014 (UTC)[reply]

There are different (related) senses of the word "evolution," so I'm not quite sure if you mean the time evolution of an individual and cell types within, or evolution of species over time (or both), but these links cover a bit of each. Check out embryogenesis for a description of what cell and tissue types form in the development of an individual human. Human_development_(biology) also gives an overview with lots of wiki links. See human evolution for how we think humans evolved. When we study evolution of organisms, and how development changes with evolution (and what the development of different organisms tells us about their evolutionary history), you get the vast topic of evolutionary developmental biology, sometimes shortened to "Evo-devo". SemanticMantis (talk) 00:00, 28 April 2014 (UTC)[reply]

There are about 200 types of uniquely identifiable types of mature cell in the human body. Primitive fungi and algae might have two or three cell types, hyphal, thallus and reproductive, and so forth. For example, and without being specifically correct, there might be a stem blood cell that differentiates into stem white cells and stem red cells, and the stem white cells might differentiate until, after various differentiations, you get the two dozen or so types of immune cell. Same with rods and cones and neurons and glial cells.

A tree can be drawn which shows which of these cells differentiate from which. That tree evolved slowly over time, and its phylogenetic development is mirrored in onto genetic development. The earliest divisions in animals, the endoderm, mesoderm and ectoderm stem cells have been mentioned above. The user wants a full diagram that shows all 200 as they develop from the zygote. The only charts I have found have been for the blood cells. I did try to see if we had an article on this a couple of years ago, but was unsuccessful. μηδείς (talk) 01:45, 28 April 2014 (UTC)[reply]

Doing a real quick search I stumbled on [8] which led me to [9]. I'm not going to take the time to look over the data and figure out what it means right now, though. We really ought to "emancipate" this data for the good of Wikipedia by some mechanism or other - looking at their topographic map I bet we can do better with a Lua module, if I can find the raw numbers. No promises though! Wnt (talk) 03:52, 28 April 2014 (UTC)[reply]

Thanks, User:Wnt, that first source is an excellent introduction into the topic the OP is looking for. μηδείς (talk) 04:15, 28 April 2014 (UTC)[reply]

A number such as 200-220 strikes me as arbitrary, and dependent on what is counted as a "difference". There are many more distinguishable types of neurons in the brain alone than that. Looie496 (talk) 14:56, 29 April 2014 (UTC)[reply]

The literature does usually say just over 200. It's also a developmental issue. If a neuron in the brain and a neuron in the peripheral nervous system are functionally interchangeable, and could have had their places swapped by manipulation during development, they would be considered the same cell type. It's a matter of differentiation between what genes are expressed (cone cells and liver cells express different genes) rather than just difference in location. Stuart Kauffman addresses the topic and its importance in his book, The Origins of Order.

That being said, in humans of course there are probably a few dozen known cell types in the brain. But that is conidered in the enumeration. According to this paper Trichoplax has four cell types, Flatworms about a dozen, Pine trees about 30, Earthworms about 60, and Mice and Dogs about 100. That probably implies that much of the difference between humans and other higher mammals does lie in the nervous system, if not also the liver and digestive system, given our more varied diets and tolerance for plant toxins, although that's a guess on my part. μηδείς (talk) 22:13, 29 April 2014 (UTC)[reply]

True, it is sort of arbitrary. To be a bit flippant, but not entirely wrong I don't think, I'd quip that given a source of white blood cells, you probably can take any given hematopoietic cell type and an arbitrary marker CDnnn, and sort out some cells that are CDnnn+ and some that are CDnnn-, and find some meaningful difference between the two. And repeat that as long as you like with one subpopulation of the next, until you run out of FACS time. :) Nonetheless -- even though the cell types recognized by histologists are quite subjective, and subjective standards are kind of bad, classical taxonomy demonstrated that a subjective standard is still relatively level and useful as a guide. It's not perfect but not useless either. Wnt (talk) 11:49, 30 April 2014 (UTC)[reply]

You're not flippant, simply wrong. That two different cells of one histological type might exhibit different markers under different circumstances is entirely irrelevant. What is relevant is that the various cell types differentiate (in an evolutionary-tree-like form) through development achieving consistent classes across the species and that while under different influences individual cells may behave slightly differently, under the same circumstances they will have the characteristics of their class. I suggest reading the sources, rather than speculating on whether male and female bell peppers are better for cooking or eating raw. μηδείς (talk) 17:20, 2 May 2014 (UTC)[reply]