Wikipedia:Reference desk/Archives/Science/2012 January 28

= January 28 =

structure of hair
complete the description of hair by filling in the gaps.the missing words are provided below. the hair that shows above the skin's surface is ........... it is composed mainly of ............ the same protein hat makes up the ........... and .............. a hair is made up of 3 layers, the cuticle,the cortex,the medulla. the ........... is the tough,outer protective layer of the hair.the cells are ............... . they allow colour from beneath to show through.they form ............., which overlap towards the hair............... the .............. is the main part of the hair, which contains the colour pigments ...............(brown/black) and ............(yellow/red). the cells in the ...........contain bundels of ............... The ................,thickness and ......... of the hair is determined by the way in which the ............ and ............ are held together. ................is formed in this layer. the ............... is the middle ............. of the hair. it is not always present and does not have a significant function.

cells              keratin             fibres            core dead               cortex              tip               cuticle pheomelanin        scales              medulla           elasticity translucent        keratin             nails             melanin fibres             skin                strength          cortex  — Preceding unsigned comment added by Payojana (talk • contribs) 00:42, 28 January 2012 (UTC)


 * It is probably better if you do your own homework. Von Restorff (talk) 00:46, 28 January 2012 (UTC)


 * It might get a bit hairy, but try looking at cells, keratin, core, dead, cortex, tip, cuticle, pheomelanin, scales, medulla, elasticity, translucent, keratin, nails, melanin, fibres, skin, strength, cortex. StuRat (talk) 01:11, 28 January 2012 (UTC)


 * Clearly hair is the place to start. To be technical, one thing in this exercise is not strictly correct - keratin is not a single protein, but a large family of proteins, and there are slightly different varieties present in each structure - indeed, in each layer of the skin the mix differs.  An example of a specific keratin is keratin 14.  Note also that type I keratins and type II keratins typically work together in each structure, with one of each type working together as a heterodimer.  But it is true that there is a fundamental relationship between all the keratins, tracking back to some single precursor long ago in single celled organisms which evolved into many different specialized forms by duplication and divergence.  Also, I would personally prefer to say eumelanin rather than melanin at one point there - to me, pheomelanin is a form of melanin, rather than an alternative to it, and the article we have is written that way also. Wnt (talk) 00:22, 29 January 2012 (UTC)

Folding spacetime
We all know what happens when spacetime bends. What happens when it folds instead? Whoop whoop pull up Bitching Betty 01:07, 28 January 2012 (UTC)


 * Wormholes ? StuRat (talk) 01:12, 28 January 2012 (UTC)
 * This is not a perfect answer but it is well worth reading. Von Restorff (talk) 01:14, 28 January 2012 (UTC)
 * I'm afraid that answer is almost totally wrong... -- BenRG (talk) 05:56, 28 January 2012 (UTC)


 * I meant, folds as in suddenly changes direction all at once, like the knife-edge folds at the edge of a paper airplane. Whoop whoop pull up Bitching Betty 01:17, 28 January 2012 (UTC)


 * General Relativity gives no way for that to happen. It's sort of like asking how a guitar would sound if its strings had folds, or how waves would propagate if the surface of a lake had folds.  It really doesn't make sense. Looie496 (talk) 02:34, 28 January 2012 (UTC)


 * All that matters to general relativity is the "intrinsic curvature" of spacetime, which affects things like the ratio of a circle's circumference to its diameter. Folding spacetime, in the sense of folding a piece of paper in two, doesn't change the intrinsic curvature, so it's a no-op as far as general relativity is concerned. Pointy bits in the intrinsic curvature are possible, though, and are better known as gravitational singularities. -- BenRG (talk) 05:56, 28 January 2012 (UTC)
 * Looie496: In your analogy, wouldn't a fold just act as a node? Or if you compare the lake to a particle in a box model with a step in it? Plasmic Physics (talk) 23:12, 28 January 2012 (UTC)


 * There are gravity waves, at least in theory. Could you have a "gravity shockwave", or is the term meaningless?  If you could, would that be a fold of some sort? Wnt (talk) 00:08, 29 January 2012 (UTC)


 * Yes, you can. A massless particle travelling at the speed of light is a source of a gravity shockwave. It is a rather curious construction, and you could say that it is a fold. As a very rough mental analogy, imagine a paper cylinder and think about an edge between the side and the top. The top and the side are flat everywhere (in the strict geometrical sense - they have zero intrinsic curvatures), the edge is unexceptional and there are no singularities, but the whole construct has unusual topology.--Itinerant1 (talk) 01:33, 29 January 2012 (UTC)

If "Solubility in Water" is 58.2% at 20 °C, what does that mean in practical terms?
Hi there.

I have Potassium Sorbate granules and I need it in liquid form as concentrated as posible.

According to Potassium_sorbate, its "Solubility in Water" is 58.2% at 20°C,

but I'm not sure what that means in practical terms?

(In other words, if I take 100g of Potassium Sorbate, what is the minimum amount of water I will need to dissolve it, and, therefore what strength Potassium Sorbate would that solution be?)

Thanks in advance

14.200.130.252 (talk) 12:38, 28 January 2012 (UTC)


 * my guess is that it is g/100ml that is meant by the %. To make a saturated solution, why dont you just add a little water to some of the powder, warm, mix and let it stand. The liquid above it will b as satuarted as it can go after a few days of standing.Staticd (talk) 13:31, 28 January 2012 (UTC)
 * Mass concentration (chemistry) would suggest your guess is correct. --Tango (talk) 17:42, 28 January 2012 (UTC)

Japanese bird name mix-up
On a website about unusual Linnaean names I visited a few years back, there was a mention of two Japanese birds of the same genus whose common names in Japanese were mixed up when they were given scientific names. Something like the bird called yosenabe in Japanese was given the scientific name Nipponavis akamichi and the bird called akamichi in Japanese was given the scientific name Nipponavis yosenabe. I can no longer find this page, and searching for "japanese birds" and "mix up" has left me empty-handed. Does anyone know the names of the two bird species who got their names mixed up? Wiwaxia (talk) 17:17, 28 January 2012 (UTC)
 * Could this be it (search for "Erithacus" on the page)? Deor (talk) 21:56, 28 January 2012 (UTC)
 * See Ryukyu Robin and Japanese Robin. Alansplodge (talk) 01:43, 29 January 2012 (UTC)
 * This is it! Thank you! Wiwaxia (talk) 09:35, 29 January 2012 (UTC)
 * Reminds me of Siebenrockiella leytensis from Palawan, which got mixed up with the more common Cyclemys dentata from Leyte en route from their respective collection sites. This caused the turtle to be classified as Critically Endangered and possibly extinct for years as the zoologists assessing its conservation status were looking for it in the wrong island.


 * Anyway, where did you get the names Nipponavis akamichi and Nipponavis yosenabe? Did you make those up? Should have put gen. nov., sp. nov. there to avoid them being red herrings. LOL --  Obsidi ♠ n   Soul   22:41, 28 January 2012 (UTC)
 * Yes, I made up Nipponavis (Japan bird), since I didn't remember the real genus name. akamichi and yosenabe were trying to recall the Japanese names (and I got the aka- part right). I admit I got yosenabe from this Japanese soup. Wiwaxia (talk) 09:35, 29 January 2012 (UTC)