Wikipedia:Reference desk/Archives/Science/2014 September 14

= September 14 =

Linea nigra
I've read our articles on linea nigra and melanocyte-stimulating hormone. Neither of them, or the references that I've read, explain why that particular line of skin is colored/darkened. So, what makes that particular line of skin so susceptible to the discoloration?

Note: I'm male. I'm not pregnant. I don't plan on becoming pregnant. I don't have any close contact with any pregnant people. This is not a request for medical advice. This is asked out of my own curiosity. Please don't close or blank this thread. Thank you. Dismas |(talk) 01:31, 14 September 2014 (UTC)


 * The line is normally (in non-pregnant people) referred to as the linea alba and is a line of fibrous tissue giving attachment to the muscles of the wall of the stomach, so it is different to the areas of skin around it, but precisely how or why it becomes pigmented doesn't appear to be clear. Mikenorton (talk) 14:30, 14 September 2014 (UTC)

The nature of electromagnetic induction
Does the nature of electromagnetic induction is always been created the nature of magnetic induction or nature of magnetic induction is always been created the nature of electromagnetic induction?--Alex Sazonov (talk) 05:44, 14 September 2014 (UTC)

How can proved that the nature of the magnetic induction is always electromagnetical, using for this experiment of Faraday?--Alex Sazonov (talk) 05:44, 14 September 2014 (UTC)
 * During of changing the polarity of the electric current in the inductive coil (in changing of polarity inductance), this inductive coil never changed its properties.--Alex Sazonov (talk) 07:15, 14 September 2014 (UTC)
 * We covered this before in an earlier question. Magnetic induction is just a special case of electromagnetic induction, where a conductor is present. Graeme Bartlett (talk) 08:59, 14 September 2014 (UTC)
 * It is not easy to change a current in an inductive coil. It is even harder the change the polarity.  You can only change the current over a period of time,  The faster you want to change the current, the higher the voltage that you need to reverse the current.  Energy is stored in the inductor, and reversing hte current means that you will take out that energy and then put in energy corresponding to the new current. Graeme Bartlett (talk) 08:59, 14 September 2014 (UTC)
 * I have not answered the second part of question 1 or question 2 (about proof). Graeme Bartlett (talk) 08:59, 14 September 2014 (UTC)
 * I been suppose that, the electromagnetic inductive volume of all inductive coils is always been constant, so that the electromagnetism of all inductive coils always is been a constant, its proved that the inductive magnetism did not made the work of the electric current. Therefore, the nature of the electric current is always been electromagnetical but not magnetical.--Alex Sazonov (talk) 09:22, 14 September 2014 (UTC)
 * Graeme Bartlett, I would be argue that inductive volume of all electrical appliances (electrical devices) is always been a constant this been proved that the work in any electric gird (electric circuit) is always been doing only by an electric current, and more by than anything (by nothing another).--Alex Sazonov (talk) 14:47, 14 September 2014 (UTC)
 * Graeme Bartlett, Only the inductive contours of the magnetic volume (not electromagnetic volume) always been create a variable work of electric current, so they always been create a variable electromagnetic induction, that is, the work in such contours always been made by the variable electromagnetic induction but not by electric current.--Alex Sazonov (talk) 16:44, 14 September 2014 (UTC)
 * If the magnet which is been inserted into the inductive coil as well as magnets had different force of magnetism which are been inserted into the inductive coil would been changed the force of electric current in an electrical circuit everything would be nice!--Alex Sazonov (talk) 18:02, 14 September 2014 (UTC)
 * Obviously, that the principal construction of all inductive contours is always been the equally (equal type).--Alex Sazonov (talk) 19:31, 14 September 2014 (UTC)
 * Inductors have different value of inductances, and that depends on the volume enclosed by the coil, and by the permeability of the material, which may be ferrite or laminated iron plates to boost the inductance. Graeme Bartlett (talk) 20:30, 14 September 2014 (UTC)
 * Inductive contours are always been created by one and the same electromagnetic force, so that all inductive contours are always been similar to each other (it is been equal type).--Alex Sazonov (talk) 06:23, 15 September 2014 (UTC)
 * Similar is not the same as equal. Graeme Bartlett (talk) 08:49, 15 September 2014 (UTC)
 * The force of the inductive of electromagnetism of the electric charge (electromagnetic induction is been presented as Ampere Force) is always been create all inductive contours. Creates any magnetism could always only the Ampere Force, but in some cases the Ampere Force is always been presented as electromagnetic induction.--Alex Sazonov (talk) 09:11, 15 September 2014 (UTC)

Graeme Bartlett, Did you think that the magnetism of the planet Earth which always been formed a magnetic contour of the planet Earth could been able to create the statics and dynamics of electric charges, if did the electric current is been really existed in the nature of the natural magnetism of the planet Earth? I been think, if did the magnetism of the planet Earth would been formed an inductive contour of the planet Earth, it would be wonderful!--Alex Sazonov (talk) 14:08, 15 September 2014 (UTC)
 * Graeme Bartlett, I always been consider the natural nature of the planet Earth as a simplest natural capacitor which is always had been a magnetic contour, but not an inductive contour, although most of modern advanced (perfect) capacitors are always had been only inductive contours.--Alex Sazonov (talk) 17:24, 15 September 2014 (UTC)

The answer to this next point of your is no, the magnetism of the earth has not created electric charge, but it does affect the motion of charged particles. See Magnetosphere and Earth's magnetic field. To your second part please read Atmospheric electricity. The earth with its ionosphere is a large capacitor. It also has the nature of an inductor, but at the low frequencies involved in magnetic field variations, or electric fields in the atmosphere, it has negligible effect. And do not be confused by electrostatic induction. Graeme Bartlett (talk) 00:02, 16 September 2014 (UTC)
 * Graeme Bartlett, thank you very much. If did the dynamics of the electric charges is always been presented in the natural nature of the planet Earth, I think that I'm right, because the natural nature of the planet Earth is always had been a constant (but not a variable) magnetic contour capacitor type (condenser type), that’s why the dynamics of the electric charges is always been presented in the natural nature of the planet Earth.--Alex Sazonov (talk) 06:59, 16 September 2014 (UTC)
 * Graeme Bartlett, If did not only Coulomb Force, but and Ampere Force are always been presented in the natural nature of the planet Earth, so that I think that I'm right!--Alex Sazonov (talk) 07:11, 16 September 2014 (UTC)
 * Graeme Bartlett, Dynamics of the electric charges is always been presented in the magnetic fields, and not only in the inductive fields, although always is been assumed that the magnetic fields are always had been only a statics of the electric charges. The question is been in that’s, what did an electromagnetic charging always had been a natural magnetism of the planet Earth? In another words saying, the question is been in that’s, what the electromagnetic component (charging component) is always been contained in the natural magnetism of the planet Earth?--Alex Sazonov (talk) 08:31, 16 September 2014 (UTC)
 * Graeme Bartlett, Do not be forgot a scientific fact in physics which been asserts that the presence of the dynamics of the electric charges in environment is always been mean the possibility of the presence of dynamics of the electric current in this environment!--Alex Sazonov (talk) 09:39, 16 September 2014 (UTC)
 * A very rare case been in the natural nature, when the Coulomb Force is been presented in the environment, but the Ampere Force in this environment could not been presented.--Alex Sazonov (talk) 10:17, 16 September 2014 (UTC)
 * Any magnetism is always been inherent a magnetic inductive, as well as the electric current is always been inherent an electromagnetic induction, although I been consider a magnetism as a factual phenomenon which did not had an inductive, so that I’m been argued that a magnetic contours of all electrical technics did not had an inductive contours.--Alex Sazonov (talk) 13:21, 16 September 2014 (UTC)
 * Alternating electric current and direct electric current are always had been one and the same nature, so that the laws of the alternating electric current are always had been compliance by the laws of direct electric current and the laws of direct electric current are always had been compliance by the laws of alternating electric current, so that any inductive and any magnetic contours which had been a variable or constant inductive are always been principally the equally (they are always been equal type).--Alex Sazonov (talk) 09:21, 18 September 2014 (UTC)

Note: Many of the world scientists been tried by using a magnet or variable magnet change the force of electric current in the electrical circuit, but this is been impossible, because change the force of electric current and voltage in the electrical circuit could been always only a work of the force of electric current or work of the electromagnetic induction in the electrical circuit.--Alex Sazonov (talk) 19:26, 16 September 2014 (UTC) - How is been right to asking a question, what work is been made by electromagnetism in the natural nature of the planet Earth, that electromagnetism really is been existed in the natural nature of the planet Earth, or what work is been made by the natural magnetism of the planet Earth, that electromagnetism really is been existed in the natural nature of the planet Earth?--Alex Sazonov (talk) 11:13, 16 September 2014 (UTC)
 * It could been assumed that the static intensity of the natural magnetism of the planet Earth is been capable to created a electric charges and dynamics of the electric charges because a electric charges and electric current and also dynamics of the electric current are always been existed in the natural nature of the planet Earth.--Alex Sazonov (talk) 18:57, 16 September 2014 (UTC)

Do people clean out the anus before engaging in anal sex?
I was googling "sexual slang terms" and found a couple that described some pretty unsanitary sex positions. Do people clean out the anus before engaging in anal sex? Does the anus have a self-cleaning function? 71.79.234.132 (talk) 18:55, 14 September 2014 (UTC)
 * Your questions seem fairly unclear to me.
 * For your first question, it shouldn't really be surprising that some people do (particularly professional porn actors before a shoot including almost definitely before any scene when the penis goes somewhere else after anal sex has begun) and some people do not, as with pretty much anything where sufficient people are involved. See these sources which unsurprisingly basically say the same thing even if not directly attempting to answer you question Enema     Rule 34 (sort of). Are you asking for statistics on averages or something?
 * For your second question, I assume you know what Defecation is. Maybe the stuff discussed in the links and also others like  which explain why there there often isn't much fecal matter in the lower bowel for someone with a decent diet who has recently defecated (but you shouldn't expect none) will answer your second question, but I'm not sure without knowing what it is.
 * Nil Einne (talk) 19:38, 14 September 2014 (UTC)


 * The last time I went down that alley was in a bathtub, so pretty clean. But after a minute or so, she called a time out because she got the urge to "self clean". Killed the mood, at least for an hour or so. She swore she didn't have to go beforehand, blamed my end of the deal. She's usually right. Probably some "switch" nerves in there. InedibleHulk (talk) 20:00, 14 September 2014 (UTC)
 * I always clean my anus before I fuck someone--it's just the polite thing to do.Miss Manners' Guide to Rearing Perfect Children. μηδείς (talk) 23:56, 15 September 2014 (UTC)
 * Why do pure gynophiles have anal sex anyway? I wouldn't do that because I wouldn't like to go back. It'd be like winning a 2015 Buggati Veyron plus it's extra costs (deductible etc.) for life (trade in for free unused 2015 when it becomes unreliable) then being offered occasional test drives in a 2015 Buggati Veyron Super Sport with aftermarket carbon fiber body and street-illegal jet engine. Besides that, uncomfortableness has no place in sex and I might wonder if she's only saying it's not discomforting/faking enjoyment to please me (give me oral) or to delay breakup (I don't want that kind of oral). I don't want a pain-loving lover either, that's perverse, and caused by child abuse. To tell the truth it's more fascinating when you're 10 or 11, only a few years from that age when caca and your anus was awesome, and can't imagine what a female looks or feels like but can easily imagine anuses (you don't want the bad feeling of diarrhea in your anal canal all day, do you?) Sagittarian Milky Way (talk) 02:44, 16 September 2014 (UTC)
 * I am unfamiliar with the alien spacecraft of which you speak, but anal sex is one way of avoiding pregnancy. Unless they have been made illegal since the 80's, the existence of combined anal-vaginal dildoes seems to imply there's a market.  As to why, pleasurewise? I don't know, spanking and dirty talk simply makes me laugh, and turns me off if it's necessary.  I'm sure I could think of a few dozen practices I don't understand, or that turn me off.  Luckfully the OP just want's to know whether or not to wash, and should ask his partner.  BTW, I do remember hearing that douching actually increases the risk of HIV for the passive partner of a male. I am sure there will be a source for that if anyone really wants it. μηδείς (talk) 03:04, 16 September 2014 (UTC)
 * Imagine that you're a pure gynophile who has a penis. Your girlfriends would let you borrow their Buggati Veyron all the time. Maybe even every day. The first day she lets you, you might want hours of driving. After awhile, you might not even want to borrow their Veyron some days. First you have to be content to enjoy her Corvettes. Then every few girlfriends, you have one who'll let you borrow her Buggati Veyron Super Sport with aftermarket carbon-fiber body and jet engine, usually not all the time and sometimes rarely. If you only date good girls but still want to do that, you're going to be waiting for a long time. Isn't that what anal sex is like? At times, states and countries have had laws against driving in that even if the owner consents. Not many men have been convicted for driving their penis or any other body part in one in the West in recent years. It's still illegal to light her jet engine in the street right in front of strangers. And rightly so. It's legal on private racetracks far from bystanders in the US In places where it's illegal to do it when no one can see, anybody with a brain would only do it when no one can see. Sagittarian Milky Way (talk) 05:25, 16 September 2014 (UTC)
 * "pain-loving lover either, that's perverse, and caused by child abuse." . Please don't offer us your WP:SOAP. Actually, the way you keep making weird car analogies, it seems like you're very interested in anal sex, or at least interested in comparing it to very expensive cars. But none of this has any place on a reference desk, so let's please end this unless someone manages to find a reference on prevalence of anus cleaning. The OP already has their basic answer and refs from Nil: some people do, some people don't. SemanticMantis (talk) 15:52, 16 September 2014 (UTC)


 * Hopefully will end soon. A reply here User talk:SemanticMantis. Sagittarian Milky Way (talk) 07:00, 17 September 2014 (UTC)
 * St. Mark's Hospital and Academic Institute in Great Britain has a |patient brochure on normal bowel function on the normal function of the bowel, including how fecal retention works - the anal canal is normally vacant unless the bowel has been stimulated by a recent meal, so that fecal matter ought to be absent after normal anal hygiene as described in our article on anal cleansing: []. Is that comprehensive enough? Can we get off the stool (so to speak) on this topic? loupgarous (talk) 08:03, 17 September 2014 (UTC)

Diarrhea
Why is it that some diarrhea only lasts for a few hours, which seems to be the case mostly after you've eaten something bad, while others such as those caused by stomach bugs can last up to a week. Aren't they both caused by bacteria or virus? — Preceding unsigned comment added by 90.192.105.196 (talk) 22:11, 14 September 2014 (UTC)


 * Diarrhea is usually caused by the poisons that the bacteria have produced. Even if all the bacteria have been killed by cooking, the poison will still be in the food and you will get ill. Diarrhea that lasts only a few hours or less can also be caused by other effects like indigestion that leads to a lot of gas and some exess fluids in your intestines. If bacteria are the problem, then you can get ill a long time after eating the infected meal. The bacteria then get into the itnestines and multiply there possibly after being dormant for a while. In case of Listeria infection, you can get ill several months after eating an infected product. Count Iblis (talk) 22:19, 14 September 2014 (UTC)


 * (ec) Diarrhea caused by a food that chemically irritates the colon or a chemical irritant like magnesium citrate is self limiting because the colon allows the food or chemical to pass too quickly to spend several hours reabsorbing the water content. Diarrhea from an infection is likely due to a bacteria or virus higher in the digestive tract shedding irritants that carry its reproductive vector out of the body over a more extended period, without themselves getting washed away. μηδείς (talk) 22:28, 14 September 2014 (UTC)
 * Why would Magnesium Citrate be in food? And is that why the short diarrhea lasting a few hours or less normally don't have any the symptoms such as fever, vomiting etc normally associated with an infection? — Preceding unsigned comment added by 90.192.105.196 (talk) 22:34, 14 September 2014 (UTC)
 * Magnesium citrate is sometimes added to food to adjust its acidity. Short diarrhea lasting just a few hours is the result of food borne toxins, and so wouldn't be expected to have the same symptoms as infection, even if those toxins are the product of microorganisms (present in the food, and not necessarily in the patient).  - Nunh-huh 03:41, 15 September 2014 (UTC)
 * Nunh-huh is right about food-borne toxins versus infections. Concentrated magnesium citrate in the form of an 8 oz soda is a typical heavy-duty over-the-counter purgative.  It will usually induce 1-3 very watery bowel movements in 4-6 hours.  The instructions usually include taking two tall glasses of water right after drinking the purgative.  This or a less irritating prescription version is usually prescribed to treat moderate constipation and for the night before a colonoscopy, or a surgical or diagnostic procedure. μηδείς (talk) 17:58, 15 September 2014 (UTC)