Wikipedia:Reference desk/Archives/Science/2013 September 25

= September 25 =

Controlled Release Medications
I have have certain medications like controlled release melatonin which seem to work mechanically, having an agent that slows there dissolution in the digestive tract. I am curious is this is the sole or typical type of controlled release medicine? Do some CR medicines have a different chemical formulation that changes or slows release or clearing in the bloodstream? I am particularly curious about Zolpidem CR. I don't find any explanation in our article or at the Sanofi website. Thanks. μηδείς (talk) 01:26, 25 September 2013 (UTC)


 * To clarify, I know from having taken oral morphine after a major abdominal surgery that it is not the morphine itself, but the metabolites that have the most effect. So I wonder if that is the case with controlled release substances--are they designed to take advantage of that phenomenon. μηδείς (talk) 03:57, 25 September 2013 (UTC)


 * We have a controlled release/time release technology pair of articles. The main methods (by concept, not ordered by popularity or usefulness in certain contexts) are gradually removing a coating to expose the active ingredient, gradually leaching the active ingredient out of a matrix or containment, or chemically cleaving the active ingredient from an inactive-complex precursor. DMacks (talk) 04:07, 25 September 2013 (UTC)


 * We answered an similar, but unrelated question, a few days ago. The answer can be found in the field of pharmacokinetics.  The rate at which a drug enters the blood stream is a matter of a combination of factors, some of it due to the chemistry of the drug compound itself and its natural rate of absorption, and some of it is because of the way the pill is prepared to control how fast the drug is released from the pill, a process called liberation.  The so-called "inactive" ingredients (those without pharmacological activity) are actually quite important here; these ingredients are called excipients and they have a lot to do with how the drug is liberated and absorbed.  -- Jayron  32  04:55, 25 September 2013 (UTC)


 * Okay, so you have both confirmed for me what I expected, there are many means of doing controlled release pills, and it may indeed be a more complicated chemical process than just a physically hard to dissolve tablet, which was the case I ran into when I inadvertently got time release melatonin (anyone who knows how melatonin works would know how silly a product that is) which I had to spend minutes chewing out of their gummy substrate.
 * So, my specific question is, which of these methods of action applies to Zolpidem CR? Our article doesn't say that they have different formulae or that one is the metabolite of the othert.  I couldn't find anything in the Sanofi literature either.  So I am curious, can someone find out which of the mentioned mechanisms delays the release of the drug? μηδείς (talk) 05:26, 25 September 2013 (UTC)


 * PS, to save confusion, I got a BA in Bio as one of my majors as an undergrad, and tested out of Chem 101-102 at an ivy league via my scores in AP chem. So feel free to talk to me about this as a big kid. It help finding the specific info which I am really looking for. Thanks μηδείς (talk) 05:38, 25 September 2013 (UTC)


 * Zolpidem CR uses hypromellose (hydroxypropyl methylcellulose) for extended release, I think, judging by the difference in ingredients between CR and regular form. Here is some info on the mechanism: http://www.colorcon.com/literature/marketing/mr/Extended%20Release/METHOCEL/English/PTEarticle.pdf Ssscienccce (talk) 05:42, 25 September 2013 (UTC)


 * Excellent, thanks. μηδείς (talk) 18:50, 25 September 2013 (UTC)


 * Also note that some medications do have slow-acting and fast-acting forms, such as insulin. Our article seems rather deficient on this aspect, so try here, instead, and particularly note the graph at the end: . StuRat (talk) 11:00, 27 September 2013 (UTC)


 * Yes, just about everyone on my father's side of the family has type II diabetes, so I am familiar with the medications. But my question here was solely regarding oral medications.  My experience is that certain oral capsules do and do not work quicker or last less time if chewn, and I was curious what the different mechanisms might be. μηδείς (talk) 04:10, 28 September 2013 (UTC)


 * Well, chewing it to break it into smaller pieces should certainly reduce the amount of time for it to dissolve and pass through the intestinal walls. However, that isn't necessarily the bottleneck.  Some meds may already do this quickly, but then take time to be metabolized by the liver, etc., into a usable form. StuRat (talk) 11:58, 28 September 2013 (UTC)

Sensation in throat
Whenever I lean my neck and head down, craning my neck I think it's called, while still standing up, I get a tingling feeling in my throat, as if a bubble is passing through it. It almost feels as if my neck is being fractured, but it isn't painful. What is this sensation called and what exactly is going on here anatomically? Bennett Chronister (talk) 05:41, 25 September 2013 (UTC)
 * Sorry - but it is against guidelines to provide medical advice. Please see Reference desk/Guidelines/Medical advice. Zain Ebrahim (talk) 09:29, 25 September 2013 (UTC)
 * A clarification: I wasn't asking for medical advice. This isn't bringing me pain or injury or anything. I'm just interested, in an academic way, in what this phenomenon is, since I don't think I've ever read about it. Bennett Chronister (talk) 15:10, 25 September 2013 (UTC)
 * Most likely you're compressing a nerve -- that's the usual cause of a tingling sensation when the body is put into a strained posture. Looie496 (talk) 15:33, 25 September 2013 (UTC)
 * It doesn't mater whether the OP feels pain or not, we cannot suggest a cause for his condition. μηδείς (talk) 20:42, 25 September 2013 (UTC)
 * Resurrecting Henny Youngman... Patient: "It hurts when I do this." Doctor: "Then don't do that." ←Baseball Bugs What's up, Doc? carrots→ 21:06, 25 September 2013 (UTC)


 * "Condition"? I thought this was something that happened normally in everybody's body when they stood like that. My question is like asking, "What goes on when I hiccup"? Surely you wouldn't close a hiccup question down.right? Bennett Chronister (talk) 02:30, 26 September 2013 (UTC)
 * The OP has been told we don't do medical advice and no serious answers have been given--feel free to answer with refs outside the hat. μηδείς (talk) 02:44, 26 September 2013 (UTC)

Courting behavior when males ram into each other head first
Is there a scientific term for such a behavior (described in the subject line)? Specifically the rams of bighorn sheep. I was wanting to see a list of other animals that also behaved similarly, but the action doesn't seem to have its own article or category. Rgrds. --64.85.215.13 (talk) 09:05, 25 September 2013 (UTC)


 * Rutting. Also practised by some breeds of deer and goat (and some humans). --TammyMoet (talk) 09:06, 25 September 2013 (UTC)


 * I saw that article (Rut (mammalian reproduction)), but figured that ramming was something that was done during the rutting season. So I was hoping there was something on that one specific behavior. --64.85.215.13 (talk) 09:16, 25 September 2013 (UTC)


 * It is neither courting nor rutting. It's called butting, or locking horns. I also found a nice obsolete word in the OED: to nurt: to push or butt with the horns.--Shantavira|feed me 12:16, 25 September 2013 (UTC)


 * However, it should be noted that many animals will do a one-sided head-butt at other times, as well, as a means of attack or defense. Thus the comic image of a person bending over when a goat "nurts" them from behind. StuRat (talk) 10:49, 27 September 2013 (UTC)

Mummification
In this distressing case (another link), what exactly does it mean to say that the boy's body was 'mummified', and what could have caused it to happen (as opposed to simply decomposing)? Our article doesn't seem to cover this - it seems to imply that mummification happens as a result of deliberate action or fairly extreme and unusual conditions. AndrewWTaylor (talk) 12:52, 25 September 2013 (UTC)
 * The body dries out, and the absence of moisture prevents or stops decomposition. The child died in december, in low temperature (near freezing) the decomposition would be slow and with a dry, cold atmosphere and constant draft (open window perhaps) the body could have dried completely. Low bodyweight, absence of food in the digestive system and severe dehydration before death would make it more likely, I assume. Ssscienccce (talk) 13:52, 25 September 2013 (UTC)


 *  Based on the first link, it sounds like the word “mummified” was used by the detective constable who discovered the corpse. It is possible he simply misspoke. Based on the description of the smell in the house, it is likely that the body was indeed decomposing. Zain Ebrahim (talk) 14:13, 25 September 2013 (UTC)
 * (e/c)Yes, mummification is a deliberate preservation of the body, whereas mummify (hence mummified) is used more loosely and can mean "of tissues or organs: to dry or shrivel up." (OED again).--Shantavira|feed me 14:19, 25 September 2013 (UTC)


 * As I understand it, the smell was coming from rotting food inside the house. They entered the house in september 2011, the boy died in december 2009.
 * The weather conditions may have contributed as well, see Winter of 2009–10 in Great Britain and Ireland. Very cold air outside would result in very low humidity inside the house. Ssscienccce (talk) 14:41, 25 September 2013 (UTC)

Effect of direction of impact on traumatic brain injury
I heard from a friend that a car crash in which your car is hit from the side is far more likely to kill you then if you were hit from the front. Basically, his explanation was that if the brain experiences sideways acceleration and bounces from left to right instead of from front to back, the middle part of the brain separating the two hemispheres (I believe it's called the Corpus callosum?) is a weak spot and is more likely to tear or suffer damage and you end up with a much worse injury. Is this actually true? If so, would that mean if you were about to drive into a wall, looking away before impact would increase your chance of brain injury?--182.55.86.32 (talk) 14:17, 25 September 2013 (UTC)


 * If I understand it correctly, supports the claim that a sideways head acceleration is more damaging than a front-to-back acceleration.  However, there are many other factors that come into play when comparing a sideways car crash with a head-on collision. Looie496 (talk) 15:26, 25 September 2013 (UTC)


 * ...the most obvious being that in a head-on collision, you have a nice soft bumper and lots of crumple-zones in front of you to absorb the energy of the collision. Some cars absorb energy by pushing the engine down and behind (which absorbs lots of energy because it's heavy!).  In a side impact, there is almost nothing between you and the oncoming vehicle and even with clever design, the car can only crumple in an inch or two before it hits you.  Another problem is that your seat back and belt stop you from moving forwards and backwards in a frontal impact - but there is much less there to stop you from sliding sideways in a side impact.  Your lap belt will hold your hips in place - but your upper body is hardly restrained at all.  A frontal impact in one of the nastiest death-traps ever built - a VW microbus (the last of which is mercifully rolling off the production line in December!) is very often fatal - which is largely because there is nothing between you and the front of the vehicle and it originally had only lap belts.  That's a good analogy for a side impact in a modern car.  Another issue is that when a car is hit from the front or back, it can usually roll backwards or forwards to retain some kinetic energy and suffer a smaller impact...but the tires on your car strongly resist being pushed sideways in a side impact.  Some newer cars now have side-impact airbags to help this situation a bit - but even so, it's not a good way to get into an accident. SteveBaker (talk) 18:04, 25 September 2013 (UTC)


 * I disagree on your tire argument. While low-speed impacts won't cause a car to move sideways, a high-speed impact will, and there it's just like a frontal or rear impact with the brakes on, in either case the car skids.  Also, rolling forwards or backwards (if the brakes are not engaged), can get you into more trouble, with additional impacts, etc., so isn't really a good thing.  And, finally, having your car start to move in the opposite direction it was headed only increases the rapid acceleration/deceleration injuries.  StuRat (talk) 10:41, 27 September 2013 (UTC)

Schizophrenia rat experiments
You know how some research experiments on Schizophrenia use rats? In order to simulate Schizophrenia in rats, it is known that scientists make an environment that is hopelessly inaccessible for the rat. This presumes that rats have some sort of desire going on. The thing is, how do scientists measure desire in rats? Is it possible that the rat may ever grow tired of the object so that the object will not be desirable at all? Also, how do scientists get access to illegal drugs like PCP in order to perform research on rats and thus simulate schizophrenia? 164.107.103.177 (talk) 15:36, 25 September 2013 (UTC)
 * As far as I can tell you are describing the paradigm called learned helplessness, but that's considered a model of depression, not a model of schizophrenia. Usually the motivation is to escape from something bad, not to gain access to something good.  There are no widely accepted animal models of schizophrenia, but our article will give you an overview of the ideas that have been batted around.  And finally, in the USA scientists can get access of controlled substances by getting a license from the FDA, although the process is often difficult. Looie496 (talk) 15:51, 25 September 2013 (UTC)


 * For more on your final question, see Controlled Substances Act, which governs research access to drugs that are not legally available to the public (at least in the USA, there are similar laws and governing bodies in Europe and elsewhere). Basically, the scientists and the producers of such drugs go through a lot of paperwork and government oversight, involving the Food and Drug Administration, and potentially other agencies. SemanticMantis (talk) 15:54, 25 September 2013 (UTC)


 * Our article on the economic concept of a Giffen_good mentions an experiment where rats were given water mixed with quinine (which is not tasty to rats). The citation in the article is the 3rd footnote.  From memory, the cited book discusses the properties of rat utility functions and how to conceptualize and measure a rat's desire for different things. OldTimeNESter (talk) 15:15, 26 September 2013 (UTC)


 * Ah, I forgot to address that part of the question. Basically scientists measure desire by the amount of work that an animal is willing to do to obtain something, or the way that it trades off with some other type of reward or (as in the example you mention) punishment.  The Behaviorists did a huge amount of work using that approach, generating reams and reams of literature. Looie496 (talk) 15:46, 26 September 2013 (UTC)

aragonite
why are most shells made of calcium carbonate instead of aragonite? — Preceding unsigned comment added by 149.152.20.214 (talk) 15:58, 25 September 2013 (UTC)
 * Our article on aragonite says that your premise is false, and that most shells are made of a combination of aragonite and calcite. Looie496 (talk) 16:07, 25 September 2013 (UTC)

The presence or absence of magnesium in sea water plays an important role in determining whether aragonite or calcite will be the prevalent form of calcium carbonate present. The levels of magnesium have changed over geologic periods and there were periods in Earth's past when aragonite was the prevalent form. see Aragonite sea and Calcite sea. Dauto (talk) 00:04, 26 September 2013 (UTC)

I seem to have it backwards in my previous post. We are actually living in aragonite sea period currently, so my answer now seems inconsistent. I'm not sure. Dauto (talk) 00:09, 26 September 2013 (UTC)

Turns out your premiss is incorrect and most modern shells include substantial amounts of aragonite which  IS  a form of calcium carbonate! Dauto (talk) 00:14, 26 September 2013 (UTC)
 * I'm not sure his premise is wrong, as the calcite article states: "Calcite is often the primary constituent of the shells of marine organisms". Calcite is the more stable form of calcium carbonate, but ultimately the type of crystal will depend on the specific circumstances I suppose. And in old fossils, aragonite originally present will have turned into calcite. Ssscienccce (talk) 07:57, 26 September 2013 (UTC)

Nautical twilight
How many kilometers above you is the daylight when it's nautical dawn at sea level? — Preceding unsigned comment added by 12.196.0.56 (talk) 18:14, 25 September 2013 (UTC)


 * For starters, Nautical dawn is when the "Sun is 12 degrees below the horizon in the morning" according to Dawn. The earth is roughly 152,098,232 km from the sun, and the Earth's radius is roughly 6,371 km. So you should be able to do some geometry from there to get your general answer. Depending on the accuracy you want, you could take seasonal and latitudinal considerations into account. SemanticMantis (talk) 18:26, 25 September 2013 (UTC)
 * Why the distance from the sun? Maybe I misinterpret the question, but wouldn't it simply be r*(sec(12°)-1) (about 143 km) ? Ssscienccce (talk) 19:15, 25 September 2013 (UTC)
 * I pictured an ant on a basketball, and a flashlight. It seemed to me that moving the flashlight closer to the basketball would change how high the ant would have to go to see the flashlight, starting from a dark portion of the basketball (i.e. the 12° dark position). But maybe I'm missing something too :) SemanticMantis (talk) 20:17, 25 September 2013 (UTC)
 * You're missing the fact that the sun is so freaking far away that you can consider it to be at infinite so its actual distance doesn't matter.
 * Ah...but to know that that is a valid simplification, you need to know how far away the sun actually is! ;-) --Stephan Schulz (talk) 23:56, 25 September 2013 (UTC)
 * Yes, it's all about how accurate you want/need the model to be ;) SemanticMantis (talk) 00:57, 26 September 2013 (UTC)
 * Now you mention it, seems I have ignored that the sun is not a point source and that the atmosphere refracts light downwards to the surface. So the first daylight would be seen when the sun's centre is about 50 minutes of arc below the horizon, making the height r*(sec(11°10')-1) Ssscienccce (talk) 18:55, 28 September 2013 (UTC)

Bestiality and interspecies mating
Did bestiality evolve from the consequences of interspecies mating? In humans, I am not sure if there is a benefit from interspecies mating, because the offspring may neither be viable nor fertile; therefore, the reproduction - as costly as it is - is futile. How did cultural notions of bestiality evolve? 164.107.214.74 (talk) 22:01, 25 September 2013 (UTC)


 * You might be interested in our article zoophilia, and concepts like ring species and hybrid species. For what it's worth, my opinion is that the answer to your first question is "no." SemanticMantis (talk) 22:34, 25 September 2013 (UTC)


 * Zoophilia is sufficiently rare that it can be attributed to simply being an abnormality. Just as people often have physical abnormalities which don't increase their chances of reproductive success, they can also have such behavioral abnormalites. StuRat (talk) 10:04, 27 September 2013 (UTC)


 * According to Kinsey, approximately 40% of farm workers indulged in this practice. Although his methodology has been criticised and his figure may be too high, I don't think it supports the idea that the practice is "rare". Tevildo (talk) 09:12, 28 September 2013 (UTC)


 * Yes, 40% seems absurd. Not sure how you can draw any conclusions from a study which you admit is flawed.  Looking at it the other way, I can't come up with any evolutionary advantage towards zoophilia.  Other unusual sexual activities, which involve sex between people, can be argued to provide an evolutionary advantage by creating strong social bonds, much as they do in bonobos, but that doesn't seem to apply here.  StuRat (talk) 11:33, 28 September 2013 (UTC)


 * I doubt zoophilia has anything to do with wanting to reproduce. Although it reminds me of this quote from Tom Lehrer about his friend "Hen3ry": "He majored in animal husbandry... until they caught him at it one day." ←Baseball Bugs What's up, Doc? carrots→ 15:49, 27 September 2013 (UTC)


 * Yes, it's most likely a consequence of the domestication of animals and the increased free time available in modern civilization. Production of offspring requires genetic compatibility, none of which any known animal species has. Not even apes. The closest one can get is Feral children. -- Auric    talk  22:45, 27 September 2013 (UTC)