Wikipedia:Reference desk/Archives/Science/2016 April 13

= April 13 =

Why are flies prevalent in some places and nearly absent from others?
Seems like there are some places where they are numerous and annoying, while other places seem to bereft of them. Perhaps it's just the presence of unburied excrement, but if that's the case how far away do you have to be from the poop in order to avoid the flies? — Preceding unsigned comment added by 50.43.36.155 (talk) 00:09, 13 April 2016 (UTC)


 * what species of flies are we talking about? --Dr Dima (talk) 01:21, 13 April 2016 (UTC)
 * The obnoxious ones. — Preceding unsigned comment added by 50.43.36.155 (talk) 02:36, 13 April 2016 (UTC)
 * They are often frequent with farm animals such as cattle, sheep and pigs. Graeme Bartlett (talk) 04:02, 13 April 2016 (UTC)
 * There are many ecological factors that can influence where flies thrive and where they are relatively scarce, but arguably the biggest is climate. Like most insect species, most varieties of flies thrive where there is relatively high temperature and humidity.  Flies are ectotherms and not very cold resistant even as ectotherms go. The incubations of their eggs and larva are also dependent on a very specific band of temperature and humidity (for most species anyway).  Finally, their food sources (which are not limited to excrement, but also all manner of decaying plant and animal life, amongst other sources) are more plentiful, accessible and easier to digest/consume at warmer latitudes. That's not to say that two regions of equal warmth and humidity can't have drastically different amounts of flies because of other factors with their ecological niche, but I think its fair to say that climate is arguably the most important variable.  S n o w  let's rap 04:27, 13 April 2016 (UTC)
 * That theory makes perfect sense. But then there's this and this and this. Wnt (talk) 12:58, 13 April 2016 (UTC)
 * Oh yes, with insecta, there are always outliers (which is why I peppered "most"); in fact, I just recently created this article on a proper arctic ant. Given enough time, species will inevitably adapt to fill any available ecological niche (especially if there is a potential dearth of predation because of an initial lack of species adapted to prey upon them.  Because insects are so massively plentiful, in terms of both species variety and individual organisms, and because their generations (mostly) have a short span, they are particularly good at filling those gaps and finding areas where they can have massive population booms, even in areas where they relatively recently (in terms of evolutionary time, which is massive itself, mind you) could not have survived and most of their closest existing relative species still can't.  Also, for insects, sometimes the difference between an area being absolutely barred to them and their being able to explode on to the scene is as small as a few degrees, so we live in very interesting times with regard to this aspect of insect ecology and its influence on the wider world.  S n o w  let's rap 16:11, 13 April 2016 (UTC)


 * Many fly species, like fruit fly and the house fly, (and the mosquito Aedes aegypti, etc.) are highly human-commensal species, and they are found at higher densities in cities and suburbs than they are in rural or wild areas. SemanticMantis (talk) 14:42, 13 April 2016 (UTC)


 * housefly, and many carrion-flies (Calliphoridae), are attracted to toilet or decomposing-food odors: indole, trimethylamine, and so on. Just do scholar.google.com search for "housefly odor attractant" and you'll get a ton of papers to read.  Alternatively, you can look at the plants that rely on flies for pollination: Amorphophallus titanum, Rafflesia (most species), Bulbophyllum (most species), and so on. They all smell like rotting flesh, or worse.  Fruit-flies (e.g. Drosophila) on the other hand are attracted to ethanol, vinegar, amyl acetate, and other compounds associated with fermenting fruit. Different flies are attracted to different odors, but I don't think you're asking about those. Hope this helps. --Dr Dima (talk) 17:41, 13 April 2016 (UTC)

'Distant antagonistic muscles'
I randomly opened a biology dictionary to 'antagonistic muscles' -- muscles that act opposite to each other, and wondered if any of our unconscious or subconscious actions are to move muscles at a distance from consciously moved ones. Are there specific cases anybody is aware of?4.35.219.219 (talk) 01:24, 13 April 2016 (UTC)


 * I'm not sure I entirely understand your question, but I'll try to give some insight into the general principles involved here. Antagonism in terms of musculature simply refers to the biomechanical arrangement and relationship between muscles and muscle groups. An agonist muscle is simply one which opposes a particular exertion of force by anther muscle, for the purposes of reversing or stabilizing the motion of that other muscle.  There are three types of muscle in the human body, anatomically speaking, but only one of these is used in volitional movement, whether through conscious or subconscious exertion--skeletal muscle.   Now as to what kind of motor function constitutes "volitional" movement, the rules get really quite fuzzy.  Ever walked somewhere and arrived, only to realize you had no memory of getting there, because you were "in your own head"?  Well, you'd probably still say you "willed" your body to conduct those movements in some sense, and the truth is that neurophysiology doesn't tell us much about where the borders between "conscious" volition movements and non-conscious movements lie, because we don't really understand much about consciousness in general.


 * But perhaps you are asking if there are antagonistic muscles which act more or less reflexively to counteract a movement after you've finished with it? The answer there is, sure, in a sense. But these actions are still subject to the weird conceptual issues discussed above.  This is further complicated by the fact that agonist muscle can have different degrees of tension, leading to a certain resting position of the part of the body in which they are incorporated.  Extend all of your fingers out while holding your hands off of any surface.  You probably have to concentrate to keep them perfectly extended; drops your volitional effort with regard to these muscles and your hand goes into a state halfway between a fist and a flat palm (but closer to the latter, probably).  But this is the consequence of the arrangement of the muscles and bones to which they are attached as much as a matter of motor function and cognition.  S n o w  let's rap 03:48, 13 April 2016 (UTC)


 * Visualize doing any act of bodily balancing in acrobatics, athletics, ballet, sports, standing at military attention, bracing for an impact, etc. Each case identifies physiological sense organs that regulate equilibrium (equilibrioception), such as the Vestibular system in the inner ear, and consciously or unconsciously invokes the appropriate pair(s) of efferent (voluntarily controlled) and reflex-affected muscles. In the skeletal muscles, the muscle spindles report information about muscle extension to assist in maintaining posture. This can be demonstrated by a normal standing person closing their eyes and waving their hand around. At no time will the person lose balance nor awareness of where the hand actually is. AllBestFaith (talk) 22:24, 13 April 2016 (UTC)


 * Yes, and actually, your example provides a perfect platform for discussing the OP's question. You correctly point out that proprioception is highly refined and can help trigger minute corrections to posture and the relative position of parts of an individuals anatomy, but to what extent can a person be said to be "consciously" aware of incorporating each action of the musculature in that process? They are generally aware of "balancing" or of moving a limb, and have a sense of having instigated that movement "willfully", but they can scarcely be said to know exactly how they are accomplishing the act through each of the countless little corrections necessary.  These are controlled by motor pathways which exist somewhere between volition and the triggering of each neurogenic muscle action.  The conscious "self" is aware of this process only in a fuzzy sense.


 * On the flip side, proprioception, and somatosensation, can be "tricked"; create a false image of a person's extremity in a location where it is not in fact located, and the sensory data the brain receives via the eyes can override the sense of where that hand is located. You can even create a false sense of tactile sensation by stroking the false hand/limb/what-have-you.  So there you have the opposite of the former example, a perceptual construct overriding actual sensory information from the sensory motor neurons and their associated neural architecture.  This is all very confusing, of course, and a source of deep division amongst scientists studying perception and cognition. One possible explanation, that most people find unsatisfying or outright unnerving, is that there is really no such thing as free-will or "decisions" in the classical sense--that we are just chemical machines, responding to stimuli in complex ways and that part of the machinery is the illusion that we willed those actions--which we create after-the-fact.  But that's a rabbit hole that, while implicated in the OP's question, we just don't have space to go into here.  S n o w  let's rap 23:40, 13 April 2016 (UTC)

Memory during sleep
By what mechanism does the brain inhibit recording of dream memories during sleep? I note a couple of things;


 * Firstly, that waking memories minutes before entering sleep can be recalled with ease, but immediately upon entering sleep the memory inhibiting is active.
 * Memory of events from earlier in a dream can be recalled while still in the dream, but immediately become inhibited upon entering a new dream or waking up.

Both of these strongly suggest that whatever mechanism is at work acts very fast upon the brain. Is it a chemical or hormone? — Preceding unsigned comment added by 182.253.36.220 (talk) 10:39, 13 April 2016 (UTC)
 * Just on the last point "chemical or hormonal" Those are essentially synonyms, insofar as a hormone is a chemical that is used to communicate signals between different parts of one's body.  -- Jayron 32 11:11, 13 April 2016 (UTC)


 * A hormone is always a chemical. But that does not make both synonyms. A chemical can be perfectly something different from a hormone, and communicate signals. Even if a substance is chemically the same as a hormone, it can be a neurotransmitter and not a hormone.--Llaanngg (talk) 12:32, 13 April 2016 (UTC)


 * A hormone is a chemical messenger. A neurotransmitter is a chemical messenger.  Ergo, a neurotransmitter is a hormone, QED.  The debate over whether a neurotransmitter is a proper hormone, or not, is akin to the stupid debate over whether a hamburger is a sandwich, and such wastes of time are below us here.  Or should be.  I know the debate exists.  It doesn't make it less stupid.  -- Jayron 32 14:50, 13 April 2016 (UTC)
 * A man is a human, a woman is a human, ergo, a man is a woman. Right? Right?
 * And I do not believe there is a hot debate around the difference between hormone/neurotransmitter. Neither do I believe it would be simply a discussion about semantics. Both are different and mutually exclusive.  Llaanngg (talk) 15:26, 13 April 2016 (UTC)


 * Take a look at this Scientific American article: Why Do Memories of Vivid Dreams Disappear Soon After Waking Up?. "Perhaps the most compelling explanation is the absence of the hormone norepinephrine in the cerebral cortex, a brain region that plays a key role in memory, thought, language and consciousness." --Llaanngg (talk) 12:27, 13 April 2016 (UTC)
 * And, as if to prove my point above, the quote describes norepinephrine as a hormone. It is also a neurotransmitter.  -- Jayron 32 15:16, 13 April 2016 (UTC)
 * norepinephrine can be released into the bloodstream by the adrenal glands as a hormone or can be released by sympathetic nerve endings as a neurotransmitter. Chemically they may be the same, their function is not. That does not make the statement "neurotransmitters are hormones" a true one. Nor it denies that hormones change the way neurotransmitters operate.Llaanngg (talk) 15:26, 13 April 2016 (UTC)


 * Note: is it turns out that Jayron is right (he's not, but let's assume he could be right), there are many articles that would need a review. Starting by hormone, neurotransmitter and Comparison with neurotransmitters. Llaanngg (talk) 15:35, 13 April 2016 (UTC)
 * This discussion means so little to me, you can be correct. I don't need to be right.  I'm wrong.  I say that uncategorically, so I can end the silly semantic discussion.  You are correct.  I am wrong.  Problem solved.  -- Jayron 32 16:02, 13 April 2016 (UTC)
 * You say you are wrong categorically? Um...., um... I think I have to think about that...for some time. ;-) 16:24, 13 April 2016 (UTC)
 * I say that I am completely wrong. There's nothing I said that was correct.  You were correct.  I was wrong.  There's no need to argue, no amount of argument from you will convince me that I am correct.  I will continue to have been wrong in what I said no matter how much you try to argue.  There's really no point to it.  -- Jayron 32 16:58, 13 April 2016 (UTC)
 * Well so long as you're wrong, I hope that also extends to being completely wrong about the stupidity of the hamburger-as-sandwich argument. I think that is a fine way to practice one's rhetoric, logic, and persuasion. It also has no place on the reference desks, and is best reserved for beer gardens and similar :) On a more serious note, I'm also collapsing this bit, because it has almost nothing to do with OP. SemanticMantis (talk) 17:55, 13 April 2016 (UTC)
 * Uncollapsed this, as there is a very clear answer to this (Llaanngg is right, Jayron is wrong). As is explicitly stated in our hormone article, a hormone is by definition secreted to the blood, and as stated in our neurotransmitter article, they signal across a chemical synapse. This means some neurotransmitters also act as hormones, some hormones can act as neurotransmitters, but the overlap between these is fairly small. Fgf10 (talk) 07:34, 14 April 2016 (UTC)
 * I'm not sure why you removed SemanticMantis's collapsing of this distracting side discussion, since 1) it contains no useful information to help the OP answer their question and 2) You don't add to the discussion by further confirming that I was mistaken in my original assessment, which I have already noted. What do you hope to achieve here?  -- Jayron 32 08:03, 14 April 2016 (UTC)
 * It may not be useful to the OP, but it is useful to people with the same misunderstanding as you. Furthermore, you only said you didn't care about 'semantics' (the difference is actually quite important), and passive aggressively backed out of the argument. Therefore an authoritative answer from a 3rd party was required. Fgf10 (talk) 08:09, 14 April 2016 (UTC)
 * You know, you STILL aren't going to convince me (or at this point probably anyone) that I could have been correct. It's quite clear from the sources provided that my initial assumptions were wrong, and I have conceded as such.  Why do you continue to argue with me as though I didn't fully admit to being wrong?  -- Jayron 32 10:27, 14 April 2016 (UTC)
 * Brit. ←Baseball Bugs What's up, Doc? carrots→ 13:17, 14 April 2016 (UTC)
 * What do you mean by Brit, Baseball Bugs?Scicurious (talk) 17:21, 15 April 2016 (UTC)

So, this is a fascinating area of cognition and yours is a question with a lot of implications, but, by way of answering it, allow me to ask one of my own. Are you sure that there was a memory to be "inhibited" in the first place? Dreams are a relatively poorly understood phenomena and the truth is that no one really understands with any empirical certainty what functional purpose they serve for the mind or brain, how exactly they are produced, or, like any other form of qualia, how the arise out of the chemical matter of the brain--other than to say, we know which neuroanatomical regions of the brain tend to be most active while dreaming is occurring.

But in any event, your association between dreams and memory is very much on-point, because the leading contemporary theories about dreaming often posit that their major function is in memory consolidation. In other words, as you sleep, your brain sets about the complicated task of organizing all of the disparate sensory and conceptual information your brain has recently processed and began to integrate into memory, to form strong long-term connections that help to make sense of our experience by connecting it with other elements of our internal semantics (using the term in its broader, rather than strictly linguistic sense). It may be that dreaming is an integral component of how we evolve our outlook, perceptions, perspective and other elements of our selves which change over time.

If this is so, then the experiential components of this process, which we call the dreams themselves, which we feel we bear witness to, are very possibly just a bi-product. To the extent you don't remember them, it's arguably because they weren't experienced in the classic sense and they don't represent information which comport with the kinds of experiences and intuitive concepts which are a part of waking consciousness; in that sense, they didn't exist as elements of the mind's functions that can be remembered, or are only partially composed of such. And this is a somewhat separate issue, but it's also possible that in some cases when people do recall dreams "clearly", they are actual constructing false memories, the way people often do in numerous circumstances when they can't recall all the details in waking life, filling in details until the story makes sense, or at least can be conceptualized in normal terms, no matter how weird the content of the dream was.  S n o w  let's rap 00:06, 14 April 2016 (UTC)

Metabolic uncoupling medications?
Are there any drugs other than DNP (2,4-dinitrophenol) which are known to increase metabolic uncoupling for the purpose of weight loss? I'd have thought there was a lot of incentive in the west for such interventions. --78.148.105.117 (talk) 11:17, 13 April 2016 (UTC)


 * There are lots of drugs that help to lose weight, with different risks and mechanisms of action - curbing appetite, making us feel full, or reducing fat absorption. Does it have to use the same mechanism as DNP? --Llaanngg (talk) 12:50, 13 April 2016 (UTC)


 * Hmmm, we should have an article uncoupling agent ... note that there have been many brilliant ideas for weight loss invented that have been withdrawn after they turned out to kill lots of people. (I can think of amphetamines, Phen-fen and ephedra off hand, but I think there are more!) Wnt (talk) 13:05, 13 April 2016 (UTC)


 * DNP is also known for killing some people. Anyway, anti-obesity medication is the corresponding article. --Llaanngg (talk) 13:22, 13 April 2016 (UTC)


 * I believe the goal of increasing metabolic rate so as to lose weight is misguided, regardless of the mechanism used. A higher metabolic rate means more oxidative stress, which causes damage to cells, accelerates aging, and shortens lifespan.  Instead we should find ways to suppress appetite, so we can lose weight AND stay younger, longer. StuRat (talk) 15:23, 13 April 2016 (UTC)


 * Increasing metabolism and increasing metabolic uncoupling are not the same thing. Llaanngg (talk) 16:48, 13 April 2016 (UTC)