Wikipedia:Reference desk/Archives/Science/2015 May 6

= May 6 =

Does the heart have nervous?
I have 2 questions: 1. Does the heart have nervous? 2. Is the electrical conduction system is considered nervous? 149.88.6.66 (talk) 08:27, 6 May 2015 (UTC)


 * Yes and probably yes (the nervous system is electric, but non-animal electrical systems use wires, not nerves). InedibleHulk (talk) 11:36, 6 May 2015 (UTC)


 * The nervous system uses a combo of electricity and chemistry to send signals (the chemistry portions slows things down quite a bit). StuRat (talk) 16:49, 6 May 2015 (UTC)


 * The heart contains a number of small ganglia (clusters of nerve cells), and also the cardiac plexus, a network of nerve fibers that distribute signals to various parts of the heart. But most likely the question relates to the network of Purkinje fibers, which are sometimes thought of as the heart's private nervous system.  The rhythmic beating of the heart is controlled by a small portion called the sinoatrial node.  Signals from the SA node are rapidly conveyed to other parts of the heart by Purkinje fibers, which are muscle cells that are modified to function like nerve cells:  they are very long and thin, and capable of conducting electrical signals efficiently. Looie496 (talk) 12:33, 6 May 2015 (UTC)


 * 1.There are nerves that go to and near the heart. 2. No. The conduction system of the heart is not considered nervous tissue.--  Mr.Pseudo Don't talk to me   14:04, 9 May 2015 (UTC)


 * 2) Why not ? Electrical pulses sending signals through the body would seem to qualify.  StuRat (talk) 15:03, 9 May 2015 (UTC)


 * "The conducting system of the heart consists of cardiac muscle cells and conducting fibers (not nervous tissue) that are specialized for initiating impulses and conducting them rapidly through the heart (see the image below)." 1. "The AV node is a highly specialized conducting tissue (cardiac, not neural in origin) that slows the impulse conduction considerably" 2. --  Mr.Pseudo Don't talk to me   19:52, 9 May 2015 (UTC)
 * P.s: It is a typical question on med school (anatomy exam). :D --  Mr.Pseudo Don't talk to me  20:00, 9 May 2015 (UTC)

"the universe was only one five hundredth the mass it is now"
FOX News isn't exactly a reliable source, but they cite this to Garth Illingworth, author of the paper about the discovery of EGS-zs8-1, estimated at 670 billion years after the Big Bang and the furthest/oldest galaxy known. The problem is, I don't know of any kind of matter creation in the matter-dominated era apart from the mysterious self-creation of dark energy, which isn't that dominant in the cosmos even if you count it - though I suppose that the condensation of galaxies and stars must have liberated substantial heat/light in the form of photons, relativistic mass, occasional particle-antiparticle pairs, and increased mass (as measured from close by) in supermassive black holes vs. their component bits due to all the fast-moving particles eaten. Still, I'd expect the mass of a collapsed galaxy cluster or uniform dust that might have preceded it would look the same from far off, so counting that also seems dubious, and again, I doubt it's enough. So can someone explain what this quote is about, or verify that it is an unfortunate news incident? Wnt (talk) 11:29, 6 May 2015 (UTC)
 * 670 million, not billion. Dragons flight (talk) 13:15, 6 May 2015 (UTC)
 * The confusion is with Fox's quarterly profits. Thincat (talk) 13:31, 6 May 2015 (UTC)
 * I'm no astrophysicist, but it seems there was a time when atoms were split into electrons and nuclei. Still stuff (in a way), but no atomic mass. As they gradually cooled back into atoms, there must have been a point when only five hundredths were finished. InedibleHulk (talk) 11:51, 6 May 2015 (UTC)
 * That's not how atomic mass works, and is not restricted to atoms, all matter has mass. 'Atomic mass' is not a mass of atoms, not is it the mass contributed by atoms in general, it is a measurement of the mass of a precise number of atoms of a particular element. Plasmic Physics (talk) 12:02, 6 May 2015 (UTC)
 * That's why I started with the disclaimer. Anything useful at all in that reference?
 * As for the sort of thing I do know about, splitting off a description of the Dark Ages with commas can make it seem like Illingworth described the time that way, rather than just saying it was from after that time. Not sure if that's the case here, but it happens. InedibleHulk (talk) 12:48, 6 May 2015 (UTC)
 * The disclaimer even more enigmatic, because atomic mass is not an astrophysical term in the first place. No, there is nothing relevant in the reference that pertains to answering the question. Plasmic Physics (talk) 03:00, 7 May 2015 (UTC)
 * I can't parse that in any way that seems reasonable to me, so I'm going to assume that it is simply a scientist-to-reporter communication snafu. Dragons flight (talk) 13:15, 6 May 2015 (UTC)
 * Well, I'm a little late to this discussion, but Wnt, you're already off the track: why are you reading Fox News for science information?
 * Among my many (free!) subscriptions, I receive a newsletter from the Keck Observatory: you can subscribe too! You'll never have to rely on second-hand media to incorrectly report science information a few days late.  Isn't it wonderful that we have a new format for mass media dissemination with the potential to shake up the old conglomerates?  Why are you using this innovative technology to perpetuate an archaic media model, when you could be using it to go straight to the sources of new information?
 * A few days ago, Keck Observatory broke this news, and here is their press release: Scientists at Keck Measure Farthest Galaxy Ever. Oh hey, it's even got a link to more technical information, and guess what quote is not used by the authors?  The very same quote that is confusing User:Wnt!  That confusing information was added by a non-scientist, probably by Fox's freelancer or staff reporters.
 * Observational astronomers who study deep sky objects talk about redshift by z number, not by mass-of-universe-as-a-ratio-to-current-value. The authors of this paper mention z > 6, which is quite distant, quite old.  Z number is a directly observable quantity.
 * Once you have a Z (7.7, in this case), then you, or your favorite cosmologist, or your favorite Fox News reporter, can plug this value into your favorite cosmological model, and then you can chug out a "distance" or an "age" or a "mass of the universe," but that is a model result, not an observed quantity. That output is meaningless unless you specify what calculation you used, or which standard model you applied.
 * Hopefully, you can see that this is a problem of construction: the more you depend on non-experts to provide second-hand, pre-digested sources of information, the farther your mental model deviates from the actual practice of science. Resultantly, you will have a more difficult time trying to consume or intuit these strangely-reported "scientific" results!
 * Nimur (talk) 13:23, 6 May 2015 (UTC)


 * Actually the same strange statement appears in the Associated Press story, so it probably isn't Fox's fault in this specific case. (The Fox story says that Associated Press reporting was used in their footnote.)  Dragons flight (talk) 13:36, 6 May 2015 (UTC)
 * Well, that explains it. The AP's chairman is junk. Or wait, no. Junck. But "chairman" is no typo, despite the sort of biology even I understand.
 * Anyway, this is science today. As to whether perception is reality, I'd need to study sellers. I mean, Sellars. InedibleHulk (talk) 14:21, 6 May 2015 (UTC)


 * I assume what they meant to say is that the universe was about 1/500 of the size it is now (and the mass density was 500 times higher). The AP article also wrongly says that the galaxy is 13.1 billion light years away. The reporter probably made that up based on the light travel time of 13.1 billion years, but it doesn't work that way. A correct figure would be around 29–30 billion light years.
 * If any Associated Press science reporters are reading this, Ned Wright's cosmology calculator will calculate this stuff for you. Enter the redshift into the box labeled "z", and click "Flat". The "comoving radial distance" is the distance you should report, and the size (volume) of the universe back then as a fraction of its current size is (angular size distance / comoving radial distance)3 1/(1+z)3. -- BenRG (talk) 17:29, 6 May 2015 (UTC)
 * I'm pretty sure that z = 7.7 doesn't work out to 1/500 of the volume either. Dragons flight (talk) 18:05, 6 May 2015 (UTC)
 * Actually of course there's an easier way to calculate the size ratio: 1/(1+z)3. Using z=7.73 from the paper, that's about 1/665, but Illingworth could plausibly have rounded it to 1/500. -- BenRG (talk) 18:34, 6 May 2015 (UTC)
 * BenRG, is this method to calculate size-ratio a standard method for which you can cite a source, or is it your own interpretation of the math? Nimur (talk) 11:34, 7 May 2015 (UTC)
 * Here are some papers that say that 1/(1+z) is the scale factor. You can work out that DA/Dnow = 1/(1+z) in a flat universe from this with a little algebra. (DA and Dnow are angular size distance and comoving radial distance, and Ωtot = 1 in a flat universe, and I could find a reference for that but you can probably just google it.) The formula I crossed out isn't wrong, just more model-dependent. 1/(1+z) doesn't assume a flat universe and, as you said, z (always lower case, by the way) is a more directly measurable quantity. -- BenRG (talk) 18:38, 7 May 2015 (UTC)

Yes, they are correct. The universe cools as it expands. Matter, as it's used here is juxtaposed against energy, not as a form of it. Whence the creation rate of stars is much greater and the wavelength of light emitted from these processes is blue-shifted (it's hotter - the red shift is distance). I suspect that the periodic table of natural elements was much smaller and much less abundant 13 billion years ago. As the universe aged, matter was created through star processes. --DHeyward (talk) 07:40, 8 May 2015 (UTC)

Personal hygiene in apes and other animals
If humans don't keep their rear ends clean, they get inflamed and then infected. We wipe ourselves to keep the area clean. How do our [close] relatives in the animal kingdom deal with this problem? It occurred to me that having fur in that area may be a help or a hindrance. --Dweller (talk) 13:27, 6 May 2015 (UTC)
 * Is that why baboons have such shiny red asses? -- Jayron 32 13:53, 6 May 2015 (UTC)
 * The other apes do not really have buttocks in the manner that we do - that's a result of our bipedalism - so they have no more problems with keeping their anal regions clean than other animals do. I believe some mammals prolapse their rectums slightly to further ensure it's a clean emission, but I don't know if any apes do that. Free tip: don't Google the term "prolapsed rectum" unless you really think you need to. Matt Deres (talk) 14:01, 6 May 2015 (UTC)
 * Thanks for the tip. So bipedalism seems to be dependent on having the ability to somehow clean buttocks? Are there no other bipedal creatures? Ummmm, how did T-Rex clean its backside? --Dweller (talk) 14:13, 6 May 2015 (UTC)
 * Tiny arms would have made it difficult to use toilet paper. Maybe he got the triceratops to help him out with that big horn of his.  -- Jayron 32 14:16, 6 May 2015 (UTC)
 * There are other bipedal creatures of course, but they have different musculature (such as the presence of tails). In birds, the feces rather infamously gets shot out the cloaca mixed with urine, so that it slides out with minimal mess. I believe it was in The Private Life of Plants that David Attenborough talked about a parasitic plant species that produced berries with extremely sticky pulps. Birds loved the berries, but would have to wipe their rears onto tree branches to remove the mess, thus placing the seed exactly where it needed to be to parasitize the next plant. Matt Deres (talk) 15:48, 6 May 2015 (UTC)
 * Everyone should watch that series, regardless of the question. InedibleHulk (talk) 16:00, 6 May 2015 (UTC)

Palm mounts
Hello,

I've been advised to bring this to science desk. Can someone help me catagorising this please, as much as you can...whatever relates with whatever... -- Mr. Prophet (talk) 18:55, 6 May 2015 (UTC)
 * Your link doesn't work. Try or Reference desk/Language. However I think you've strongly misunderstood the comments there. No one was seriously suggesting you bring it here. What they were suggesting is that if you asked the question here, it's likely to get an even poor response because what you're asking about is completely unscientific and this is the science desk not the utter nonsense desk. Nil Einne (talk) 19:01, 6 May 2015 (UTC)
 * Yes, COMPLETELY! Thank you for waking me up, I forgot that Wikipedians use the subscript code to joke around sometimes (including myself who started using it recently). Regards. -- Mr. Prophet (talk) 19:14, 6 May 2015 (UTC)
 * I suggest that you just guess at the categories, and it is unlikely that you will be proved wrong.   D b f i r s   20:13, 6 May 2015 (UTC)
 * Thank you thank you thank you! -- Mr. Prophet (talk) 08:43, 7 May 2015 (UTC)
 * Palmistry. Sleigh (talk) 03:44, 7 May 2015 (UTC)
 * I tried it, I hate other websites too. I sometime correct my notes with it... Thank God people in Wikipedia (or Wikipedia users) are all good! Evil prevails where I'm, people would rather learn the vice part more than the virtious part. -- Mr. Prophet (talk) 08:43, 7 May 2015 (UTC)