Wikipedia:Reference desk/Archives/Science/2015 April 10

= April 10 =

Is there any hormone which exists only in human males rather than female, or opposite?
149.78.253.71 (talk) 01:11, 10 April 2015 (UTC)
 * Not that I am aware of off the top of my head. Even hormones that we link to more specific gender functions, such as testosterone and estrogen, are present in both genders and useful in both. I don't know of a male use for progesterone, but it is found in males, regardless. --OuroborosCobra (talk) 11:32, 10 April 2015 (UTC)
 * Note sure if Human placental lactogen is produced in males after birth. In females it should be produced during pregnancy. (Prolactin however is produced and important for both.) Nil Einne (talk) 13:44, 10 April 2015 (UTC)

Allura Red AC
What does the AC stand for? — Preceding unsigned comment added by Wade sforzando (talk • contribs) 01:30, 10 April 2015 (UTC)
 * Our queriant is asking about Allura Red AC, a food colourant. LongHairedFop (talk) 10:39, 10 April 2015 (UTC)
 * As a guess, it might be azo coupling LongHairedFop (talk) 10:41, 10 April 2015 (UTC)

Metallic-like organic compound?
Hi there,

Is it possible that an organic compound would behave similarly to a metal, without a metallic atom? Exx8 (talk) 07:30, 10 April 2015 (UTC)
 * Which properties of a metal? Spider silk has a tensile strength similar to steel.  Graphite is an electrical conductor.  -- Jayron 32 08:55, 10 April 2015 (UTC)
 * Not only. In the whole of the properties. Exx8 (talk) 09:35, 10 April 2015 (UTC)
 * Still going to need to tell us what properties. Matter has tons of them. We can list things until the cows come home and if you don't list for us what you are looking for, you can keep telling us we haven't found it. --OuroborosCobra (talk) 11:30, 10 April 2015 (UTC)

Is there any relationship between limescale and nephrolithiasis or bladder stones?
Could it be any relationship between drinking limescale (kettles) to nephrolithiasis or bladder stones? What does happen in person's bodies when they drink water with limescale? 149.78.253.71 (talk) 09:06, 10 April 2015 (UTC)


 * That's a combo of minerals, but I believe at least some of them bind with fats in the small intestine, and then pass normally from the body in the feces. StuRat (talk) 02:10, 11 April 2015 (UTC)

Higher atmosphere= More homogenized Earth?
Hi there,

If the Earth had had larger atmosphere,

Would it have been more homogenized on its climate?

Exx8 (talk) 09:39, 10 April 2015 (UTC)


 * Maybe, maybe not. This kind of counterfactual question is hard to address- what else would be different to make this change? Mass of the Earth, power of the sun, etc etc. Anyway, Jupiter has a lot of atmosphere, and it's not very homogenous, same for Saturn, see Atmosphere of Jupiter, which details all kinds of atmospheric dynamics. I suspect you're thinking that more atmosphere would sort of give more room for mixing, and hence even things out, but that's not the way it works. I suppose someone could set up a General_Circulation_Model and increase the amount of atmosphere to see what happens, but I couldn't find any published work along those lines. SemanticMantis (talk) 17:19, 10 April 2015 (UTC)


 * All other things being equal, the larger the medium for heat transfer, the more uniform or quickly uniform the heat transfer, as if the atmosphere were an oversized water jacket. μηδείς (talk) 22:10, 12 April 2015 (UTC)

Can a rectovaginal fistula lead to pregnancy?
Is it possible for somebody to become pregnant through anal sex if she has a rectovaginal fistula? I hate to ask this, but I couldn’t find information on this. --66.190.99.112 (talk) 12:38, 10 April 2015 (UTC)
 * By definition it's possible, but what someone is doing having anal or vaginal sex when they have such a fistula is the bigger concern, as is the need to see a specialist and a as surgeon immediately. μηδείς (talk) 16:18, 10 April 2015 (UTC)

How many cell types does the heart have?
15:12, 10 April 2015 (UTC) — Preceding unsigned comment added by 149.78.253.71 (talk)
 * See Heart. While it does not itemize it into a neat little list, you can easily extract the various kinds of tissues in the heart, and from there figure it out for yourself.  -- Jayron 32 16:23, 10 April 2015 (UTC)
 * Actually questions of this sort are always very tricky, because there is no clear definition of what constitutes a single "type" of cell. An additional factor is that there is ambiguity about exactly what belongs to the heart.  Obviously the muscle cells, but what about the walls of the blood vessels that run through it, or the nerve ganglia that lie on its surface? Looie496 (talk) 18:08, 10 April 2015 (UTC)
 * Read the article on cell type as a start. μηδείς (talk) 18:53, 11 April 2015 (UTC)

Chemistry
Can someone please help me with this? I don't understand what this is asking.

Describe in detail what you know about the enthalpy, entropy, and free energy changes when a sample of gas condenses to a liquid. How does temperature affect these changes? 108.33.159.120 (talk) 17:34, 10 April 2015 (UTC)


 * You are forum shopping. You were advised at the Teahouse that this appeared to be a homework question, and that we do not answer homework questions.  You were told that if you had more specific questions, you could ask them at the Reference Desk.  This is the original question, not a more specific question.  Robert McClenon (talk) 17:39, 10 April 2015 (UTC)


 * I'm sorry, thats not what I was trying to do. I understand that this is a homework question. I'll be more specific. Is free energy the same as spontaneous? Please don't be angry with me. 108.33.159.120 (talk) 17:42, 10 April 2015 (UTC)


 * And anyways, I need help getting past the STUCK point.108.33.159.120 (talk) 17:43, 10 April 2015 (UTC)


 * No, it's OK. You were redirected here, and this is the correct place to ask.  However, as I explained in the last location you asked, you might want to start telling us how YOU would answer the question, and see if we can confirm your answer or critique it in some way.  What the question is asking is to explain the changes in certain thermodynamic quantities when a substance changes from a gas to a liquid.  So, as say steam condenses to liquid water, the values of enthalpy and entropy and free energy all change.  What the question wants to know is how those values change.  And it also wants to know what the role of temperature plays in it as well.  Does that help at all?  -- Jayron 32 17:45, 10 April 2015 (UTC)

Drag in Le Sage's theory of gravitation
One of the problems with Le Sage's theory of gravitation is that Earth will experience drag and eventually come to a halt, sink into the Sun, and be destroyed. I don't disagree, but the description of this problem isn't complete enough for me. I figure it is because my understanding of relativity must be flawed. So, this is my understanding. Please correct my ignorance... Earth is moving through space. Assume that there actually are tiny little specks of energy speeding around at the speed of light. Those coming towards the leading side of the Earth will be travelling towards the Earth at the speed of light. Those coming at the waning side of the Earth will be travelling towards the Earth at the speed of light. If the Earth doubles in speed, the relative speed of the little particles will be the same. The ones on the leading side won't be coming towards the Earth any faster. If the Earth comes to a stop, the ones on the side that was leading won't be coming any slower. They will still be coming at the speed of light. So, no matter the speed of the Earth or direction of travel, the incoming particles will always be heading towards the Earth at the speed of light. That makes drag difficult to describe. As the Earth moves along, the leading side won't be hit by more particles because that would require the particles to move towards the Earth faster. The waning side won't be hit by less particles, because that would require the particles to move towards the Earth slower. I simply don't know where I'm wrong and I know plenty of people here will gladly expose my mistakes. 209.149.113.89 (talk) 17:44, 10 April 2015 (UTC)
 * Energy is not a speck, it is not matter. Energy is a means to quantify change.  We do have models that use particles to model the behavior of energy.  But energy itself is not a substance.  Energy is a property of a substance.  For example, imagine we have a person named John.  We can take a property of John, like say his height.  When I say "John is 175 cm tall", I'm describing a property of John.  But you can't carry around a bucket of height.  Tallness is not a material you can hold in your hand.  To speak of it this way is meaningless.  It sounds silly to say "Here, we have little specks of height, and if we gather enough of these specks, we can carry them around."  That's nonsense.  In the same way, energy is a property of something, it is not really a substance that can be carried around or occupies a space or anything like that.  -- Jayron 32 17:55, 10 April 2015 (UTC)


 * I understand your point, but it doesn't address the problem. The Le Sage theory states that gravity is created by tiny particles travelling at the speed of light, slamming into everything. The argument against the Le Sage theory is that objects moving through a medium of these particles will experience drag because the objects will hit more particles in front and less from behind. But, that assumes that as the objects move, oncoming particles will relatively speed up while tailing particles will relatively slow down. 209.149.113.89 (talk) 18:51, 10 April 2015 (UTC)


 * If you are moving towards a particle source you will encounter more particles per unit time than if you are moving away from it. That's true because the particles have to catch up with you, even if they are moving at the speed of light.  Dragons flight (talk) 19:47, 10 April 2015 (UTC)


 * If the tiny particles are moving at the speed of light, they are not matter. Because matter cannot be accelerated to the speed of light.  Now, light itself does create drag (see Radiation pressure) because of the relativistic mass of light, as noted in our article, the drag caused by light has to be taken into account in long-distance space travel, for example.  So, the effect is real.  I have no idea what this means for the Le Sage theory.  You may want to read up on gravitons, which are a hypothetical gauge boson, the gravity equivalent of the photon.  Still, since photons create drag, and we haven't crashed into the sun because of them, I'm not sure why gravitons would do that either... -- Jayron 32 21:01, 10 April 2015 (UTC)


 * It's worth noting that at the time of Le Sage, the speed of light was understood as just a very fast speed, and not an absolute limit. At the time there would have been no problem imagining moving faster than that or that relative motions were additive in the normal way.  Dragons flight (talk) 22:24, 10 April 2015 (UTC)


 * My problem is not discounting Le Sage's theory. My problem is Feynman's reasoning. He said that these "particles" (assuming that they did exist) would cause drag. I couldn't see how something travelling at the speed of light could cause drag. In my mind, you start with "If you are travelling at 99% the speed of light and turn on your headlights, how fast will the light travel as it comes out of your headlights?" Reverse that. "If light is hitting the front of your car and you speed up to 99% the speed of light, how fast will the light hitting your car be travelling?" However, it was noted above that photons do create drag. I fully understand the effect of drag at the speed humans travel. In my mind, I'm having trouble distinguishing between the absolute speed of these imaginary particles (which is supposed to be the speed of light) and relative speed if you are moving towards or away from them. 75.139.70.50 (talk) 00:11, 11 April 2015 (UTC)
 * This "drag" is an inherent consequence of the assumptions Le Sage sets up. He assumes the existence of some particle which can carry and transfer momentum.  He demonstrates that this momentum transfer would look like an inverse-square law of attraction - similar to the force of gravity - but only solved for the normal direction of incidence.  If you solve the very same equation for all directions of incidence - and this is something we can now do because we have the methods of calculus that were barely understood in 1690 - then you find that the momentum transfer has to imply a shear force that we do not observe.  If you want the complete answer, we'll have to go through a gorey mathematical treatment - this is the sort of thing that might honestly take a solid hour of physics-equation-solving at a university-level.  Anyone who can correctly waltz through 60 minutes of physics equations usually charges money for the skill!  Furthermore, unless you take a very advanced "history of wrong physics" course, you'd be wasting your time to re-disprove every historical mathematical inaccuracy that was ever forwarded!  It takes a lot of effort to rigorously prove wrongness; few professors will waste an entire precious lecture to work the details out; fewer would publish their notes to the internet at large.  ... Anyway, if you'd really like to read Feynman's run-down, CalTech hosts an archive of his entire gravity lectures.  These chapter notes would typically be spread over several days of university-level classwork.  Take some time to digest them.  And remember!  These are the easy lectures - physics for first-year, mostly-non-major students.  There is almost no math in his treatment!  Nimur (talk) 15:36, 11 April 2015 (UTC)

Suppose you are traveling at speed v. After time t, you will have moved distance vt. In the forward direction, you will have encountered all photons within a distance equal to the sum of the distance you traveled plus the distance the photons traveled, $$vt + ct=(v+c)t$$. In the reverse direction, any photons within a distance equal to the distance photons traveled minus the distance you traveled will have caught up, $$ct - vt = (c-v)t$$. Assuming equal illumination in both direction, the force you feel will be proportional to $$(c+v)t - (c-v)t = 2vt$$. Hence the drag. Dragons flight (talk) 01:29, 11 April 2015 (UTC)


 * This sure sounds a lot like the virtual particle explanation of the Casimir effect - a model for which I admit a similar disdain, as the interaction of real fluctuations of the positions of particles within the plates makes far more sense to me than the ability of virtual particles to measure the conductivity of plates at the nodes where they are never present. But one thing about the virtual particles in that explanation (or any explanation involving virtual particles) is that there have to be infinitely many of them, in "every possible frame of reference", i.e. at 0.99c there is just an infinite a sea of virtual particles going faster than that as going slower.  The same was not available to Le Sage because, well, there was only so much people would believe in the 1600s!  (Correct me if I'm wrong) Wnt (talk) 19:06, 11 April 2015 (UTC)


 * Well, indeed no relativistically invariant effect can cause a drag, whether it's Lorentzian or Galilean relativity, because there's nothing to drag towards—no velocity is slower than any other. But I'm not sure Le Sage's gravity would be logically coherent with an infinite number of particles with arbitrarily high velocities.
 * The virtual-particle explanation of the Casimir effect deserves your disdain, as Robert Jaffe pointed out years ago in hep-th/0503158. -- BenRG (talk) 06:04, 12 April 2015 (UTC)

Earthquakes
Am I correct in thinking that the most damaging earthquakes have small ground accelerations, medium ground velocities and high ground displacements? — Preceding unsigned comment added by 94.14.146.60 (talk) 18:09, 10 April 2015 (UTC)


 * USGS_magnitude_8_earthquakes_since_1900.svg vertical up and down movement is less like to cause as much damage to buildings than a horizontal side to side movement. It is the horizontal movement that walls (of buildings) are least resistant to. So a small horizontal movement may effect more damage than a larger up and down movement.--Aspro (talk) 18:37, 10 April 2015 (UTC)
 * S-wave is the type that oscillates perpendicular to the direction of propagation, P-waves are the compression waves that move in the direction of propagation. Seismic wave details these, as well as the several type of surface waves. Surface waves generally do more damage than the body waves, which are used to locate epicenters and time of the event. Here are a few refs that discuss the types of waves and how they affect structures , and they also have better illustrations than our articles. As for actual damage from historical earthquakes, that depends a lot on where it happened, and what types of structures were there. The same earthquake in the middle of Siberia might cause very little damage, compared to if it occurred in NYC. So most damaging is often a matter of where the quake occurred, not what its seismic features are. Here are some lists of most damaging/deadly earthquakes, not the large variation in physical attributes:  . From Lists_of_earthquakes, we have this nice figure, which shows that fatalities and damage are only loosely related to magnitude. SemanticMantis (talk) 19:24, 10 April 2015 (UTC)


 * In general the degree of damage is directly related to the intensity of shaking, which is directly related to the peak ground acceleration - the intensity is measured using the Mercalli intensity scale. In severe earthquakes the peak ground velocity is more important . For any given magnitude the shallower the earthquake, the greater the maximum degree of shaking. Mikenorton (talk) 20:21, 10 April 2015 (UTC)


 * When looking at the degree of damage, where the earthquake hits is at least as important as the characteristics of the quake itself. Does it hit near a large population, living mere meters above sea level, with structures not designed to withstand it ?  Is the city a fire trap, built on unstable landfill ? StuRat (talk) 00:55, 11 April 2015 (UTC)