:<small>It's very simple. [http://knowyourmeme.com/memes/bubb-rubb The whistles go ''woo woo''!] --[[Special:Contributions/47.146.63.87|47.146.63.87]] ([[User talk:47.146.63.87|talk]]) 07:52, 24 May 2018 (UTC)</small>
:<small>It's very simple. [http://knowyourmeme.com/memes/bubb-rubb The whistles go ''woo woo''!] --[[Special:Contributions/47.146.63.87|47.146.63.87]] ([[User talk:47.146.63.87|talk]]) 07:52, 24 May 2018 (UTC)</small>
::A [[Decibel]] abbreviated dB is a ratio on a logarithmic scale and the term 127.6 dB means only "5.012x10<sup>12</sup> times as powerful". That usage neglects to explain the power reference (what power is 0 dB?). [[Sound power]] levels in decibels are meaningful only when expressed with a suffix to define their reference. For example, the OP might mean dB ref 10<sup>−12</sup> W (threshold of hearing), dB(A) (a [[A-weighting|perceptual frequency-weighted scale]]) or something else unspecified. [[User:DroneB|DroneB]] ([[User talk:DroneB|talk]]) 11:20, 24 May 2018 (UTC)
::A [[Decibel]] abbreviated dB is a ratio on a logarithmic scale and the term 127.6 dB means only "5.012x10<sup>12</sup> times as powerful". That usage neglects to explain the power reference (what power is 0 dB?). [[Sound power]] levels in decibels are meaningful only when expressed with a suffix to define their reference. For example, the OP might mean dB ref 10<sup>−12</sup> W (threshold of hearing), dB(A) (a [[A-weighting|perceptual frequency-weighted scale]]) or something else unspecified. [[User:DroneB|DroneB]] ([[User talk:DroneB|talk]]) 11:20, 24 May 2018 (UTC)
==Colin Wilson's ''Spiderworld''==
Can someone please tell the correct order of all the parts included in this series ? On net info is incomplete or incorrect at most places. Thanks [[User:Jon Ascton|<span style="border:1px solid DarkGreen;padding:1px;"><font style="color:White;background:DarkGreen" size="0"> Jon Ascton </font></span>]] [[User talk:Jon Ascton|<font color="DarkGreen" size = "0">(talk)</font>]] 08:06, 25 May 2018 (UTC)
== Weird pond creature ==
== Weird pond creature ==
Revision as of 08:06, 25 May 2018
Welcome to the science section of the Wikipedia reference desk.
The best answers address the question directly, and back up facts with wikilinks and links to sources. Do not edit others' comments and do not give any medical or legal advice.
What could a human notice if his antipodal hemisphere instantly disappeared?
Without the help of technology or other humans (i.e. Internet, seismometers, Internet feeds of seismometers, grandma tweeting you Internet feeds of seismometers)
What's the new (extremely temporary) gravity strength? How close to spherical would the hemisphere centered on you get before you're unconscious? Sagittarian Milky Way (talk) 04:17, 19 May 2018 (UTC)[reply]
This is a bit hypothetical! How would this happen? Blasted by a stream of neutron star fragments? Anyway the gravity would drop a bit so you would notice that first. Next you would be hit with massive seismic waves. Air would disappear at about the speed of sound. You could expect that the remaining hemisphere would absorb so much energy from planetary reconfiguration that it would be turned into a magma ocean. Graeme Bartlett (talk) 06:45, 19 May 2018 (UTC)[reply]
The one thing we can be sure of is you get a 1/30 second grace period due to the speed of light, though a stickler will insist that during that period the Event hadn't happened "yet". Relativity sticklers will also note that the faster you get rid of the mass, by any means, the more you mess with space making gravitational waves; i.e. gravitomagnetic effects become relevant.
Removing one hemisphere implies that material at the center, formerly under no gravitational field, would suddenly be pulled to one side, and hence could release energy by falling. On the other hand, the pressure would reduce from insane to zero in an instant, so it would also push outward. The inner core surface is estimated at 5430 K and the boiling point of iron at atmospheric pressure is 3134 K, so a rather impressive explosion is to be expected. However, note that the core of a half-sphere is still a lot lower than the outer surface. I don't know how you'd begin trying to calculate if the explosion reaches the lip of the crust. To take a wild guess, I'd say figure the heat capacity of liquid iron, i.e. (5430K - 3134K)*heat*core volume, figure out how much iron that can vaporize in moles, figure out how much volume that takes at 1 atm, and see if it fits in the flat side -- but I know that's an equilibrium, but an explosion isn't.
To find the center of a hemisphere, you set up some nested integrals in polar coordinates ... lolno, you go and do a web search and let your skills rust a little longer. [1] It's 3/8 of the way in. That means that if West Berlin is just on the good side of the Event boundary, the gravity that was formerly straight down is now coming from R down and 3/8 R over, i.e. it is off by tan-1 (3/11), or 15.2 degrees. This would be a bad time to have a house on the west side of a lake, though then again, the water might get there just in time to put out the fire from that burning core material, I dunno. ;) But actually that's just an approximation - a planet's gravity seems to come from its center of gravity because it's a sphere, but gravity doesn't come from the center of gravity of the Cavendish apparatus or any other un-planet-like shape. I suppose we could do a set of integrals ... but this one would not be in polar coordinates. But using the approximation, we know that the two halves of the earth pulled equally, summing the cos(+-15.2deg) components of each but cancelling the sin(+-15.2deg) bits, so gravity is at 51.8% or so of what it was. Sounds like a great time to launch a rocket ship, but it better be a fast one. Oh, but if you're at the center of the hemisphere, let's say, somewhere between El Dorado and Cayambe Coca Ecological Reserve in Ecuador, then you are 3/8 closer to the "center of gravity", so by an increasingly dubious approximation you should get 51.8% * 121/64 = 97.9% gravity. Hmmmm. ;) Wnt (talk) 16:55, 19 May 2018 (UTC)[reply]
Well if you remove half the mass and have the Earth settle into a smaller sphere of the same density, the new gravity is (1/2)^(1/3) ~ 4/5 g. So the 98% for the top of the lone hemisphere isn't unrealistic at all IMO. 93.142.87.187 (talk) 05:35, 22 May 2018 (UTC)[reply]
What to call it?
I'd like to know what to call this condition so I can do some research to understand it better. I'm not asking for medical advice.
I have trouble remembering things I want to do. For some time I've relied on visual clues, like placing objects in appropriate places. I put things in my calendar but sometimes forget to look there (I don't have many calendar events). Sometimes I remember the day but not the time.
On a cruise recently the problem was magnified. The ship each day provided a schedule with a few dozen entertainment opportunities, and I would pick three or four I was interested in. But I had a hard time remembering not only the time and place, but even what the event was. (To tell the truth, I wasn't very committed to most of them.)
What you describe sounds to me like the perfectly normal performance of an ordinarymemory (of someone who has not adopted special techniques of memory improvement). Some tactics to avoid the problems you mention are obvious: Forget to look in your calendar/diary? – form the habit of doing so on a regular basis, e.g. at breakfast. Forget times of events? – check those written in the calendar/diary, that you carry on you, more often instead of trying to memorize them. Become confused by many-choiced schedules of events? – Highlight the ones you're most interested in on a printed schedule and carry it with you; maybe mark back-ups in a second colour in case you're prevented from attending a first-rank choice. (Your cruise ship scenario is similar to that encountered at any large Science fiction convention, of which I have extensive experience, most of it in a less-than-sober state :-).) {The poster formerly known as 87.81.230.195} 2.221.82.140 (talk) 21:30, 19 May 2018 (UTC)[reply]
How do milk and eggs whilte function as anti intoxication?
I always used to hear that milk is used in case of intoxication but I didn't take it seriously and it was for me as a myth. But today I was read in allegedly academical book (pharmacology - Odessa university): "Inactivation and binding of the poison in the stomach should be performed simultaneously to rinsing.] Potassium permanganate, tannin, activated carbon, egg whites and milk are used for these purposes." (I found the same sentence in Wiki university...) then my question what is the mechanism that these things fight the intoxication? 18:23, 19 May 2018 (UTC) — Preceding unsigned comment added by 93.126.116.89 (talk)
My understanding has always been that they react with stomach acids and enzymes to form a jelly like substance which forms a protective layer coating the stomach lining, and thereby reducing the absorption of toxins. I think that comes from First Aid training some 50 years ago. Wymspen (talk) 19:35, 19 May 2018 (UTC)[reply]
Those substances have different mechanisms of action, so they're not equally useful for all poisonings. Potassium permanganate as an oxidizing agent to chemically modify (hopefully inactivate) a poison, and activated charcoal because it binds to many poisons due to its large surface-area for non-specific binding of a wide variety of toxins. I don't know the proposed mechanisms of egg white, but it may be much as for the activated charcoal, a close analogy being the very common phenomenon of plasma protein binding, an effect which greatly reduces the free concentration of many drugs in the blood plasma. As an aside, not that the main protein in the plasma is albumin, and egg white is also known as albumen. Milk also contains proteins which might serve the same function, while its fat might isolate lipophilic drugs and slow stomach emptying, which would slow toxin absorption (which largely occurs in the small intestine). There are drugs which line the surface of the stomach, like sucralfate, but they are used to protect the oesophagus/stomach in cases of ulceration rather for poisoning; they don't really help absorption because that doesn't take place to a significant extent in the stomach. Klbrain (talk) 22:25, 20 May 2018 (UTC)[reply]
Yet it seems like the ability to set fundamental speed limits however you look at an evolving system has to be something with an importance comparable to the level of relativity -- with which these speed limits are said to have nothing in common by all involved. (The Bekenstein bound apparently can be used to derive general relativity from scratch, if you are very good at physics; it seems superficially related to these others but what do I know?)
At a real dumb level, I saw a mention that one of the bounds was basically the Planck constant. At a glance this kind of makes sense, in that the J * s units of that can be divided by time or energy to give (in Margolus-Levitin theorem, with a 4 thrown in) a time to make a change in energy. The idea would be that anything heavy has a de Broglie frequency, or at least a de Broglie wavelength, that limits how fast it can change, the more the lighter it is. That said, I don't get how an "average energy" as our article talks about can exist; I mean, can you have a dense blast of energy in one region of space and a weak trace of energy next to it, and when you average them, now the weak energy can beat the limit? How do you decide what to average? Etc.
Anyway, I wanted to throw this question out there, see if someone can pick out some useful epitopes for a person to latch onto, maybe you could start some kind of "quantum speed limit" article (or maybe that's a bad name!), maybe you could tell me if this is majorly important to the progress of physics or 'trivial'. Wnt (talk) 22:42, 19 May 2018 (UTC)[reply]
Is this sequence of reaction mechanism steps correct? In particular, in the first step, the reactants contain a cation and an anion (plus a neutral molecule shown over the reaction arrow), but the products show a neutral molecule and a cation. Charge is not conserved, and there are no omitted spectator ions as far as I can see. Looking at the charge shown on the Iodine in Diacetoxyalkoxy Periodinane, the iodine had a positive charge in the reactant and 6 electrons (4 bonds and a lone pair), but then still has the charge in the product despite now having 7 electrons (5 bonds and a lone pair). It seems to me like that charge is not correct. In the second step, it has the opposite problem. The charge disappears from the reactants to the products despite it having the same number of electrons. Again, charges on the left and right don't balance (net positive charge on the left, no net charge on the right). I know sometimes in electron pushing to metals that are undergoing redox the electrons are omitted (since they're not held as lone pairs), but iodine is a non-metal, and the lone pairs are shown. There's no pushing that is summoning electrons from iodine that were previously omitted, or indicating electrons that disappear into iodine. I would think the steps should appear thus i.e. without the positive charge indicated on iodine in diacetoxyalkoxy periodinane. 103.228.155.51 (talk) 01:59, 20 May 2018 (UTC)[reply]
The first problem is that the original structure of Dess–Martin periodinane is not correct: all three acetates should be bonded to the I. But either way, the result of the first step indeed should have a neutral iodine atom. See our article about the chemical that I linked, or also Dess–Martin oxidation that appears to be an incomplete/overlapping subarticle about the reaction you are discussing. DMacks (talk) 03:26, 20 May 2018 (UTC)[reply]
Oh, that's interesting. I can't find a single other source that depicts DMP as an ionic species. Thanks for that answer. Very helpful. 103.228.155.51 (talk) 03:49, 20 May 2018 (UTC)[reply]
@DMacks: are you sure that the first ionic structure is inappropriate here? I'm wondering if there might be a "step 0", not shown for this reaction, where the -OAc is lost more or less spontaneously, leaving an I+ to react with something else in an SN1 type reaction. I suppose the isopropanol could lose a proton first and replace the -OAc in an SN2 type reaction, but I'm not sure you can use such basic conditions on DMP. (but yes, the I+ on the right side seems like a simple mistake) Wnt (talk) 12:34, 20 May 2018 (UTC)[reply]
I haven't seen literature support for a pre-dissociation (SN1-like) mechanism. DMP oxidations are usually done in non-protic fairly non-polar solvents (but I cannot find a ref specifically analyzing solvent/temperature effects). Papers examining mechanism/kinetics seem to treat the acetate/alkoxy exchange as a single step for purposes of reaction rate and especially Keq analysis. And doi:10.1021/jo901841v provides NMR evidence that DMP itself does not rapidly exchange acetate with added acetate in solution, but instead finds distinct non-equivalent (non-exchanging) acetates on the I. Instead, that ref supports exchanges of the I on the two O of acetate is rapid via an intramolecular shift (tighter not looser attachment of them?). DMacks (talk) 13:46, 20 May 2018 (UTC)[reply]
What is sodium nucleotide?
What is Sodium nucleotide? I saw it in a list of choices as a part of MCQs about blood components... but when I googled it I found a little bit information about it (something like 250 results on Google!), so I had a thought that maybe it is known in another name? --93.126.116.89 (talk) 10:32, 20 May 2018 (UTC)[reply]
The term seems unfamiliar, but I assume that they mean something like ATP disodium salt [4]. Nucleotides contain phosphate groups, which are related to phosphoric acid; hence they are not usually neutral at physiological conditions but carry a negative charge (which is of relevance to DNA melting, etc.) Which means that if you try to isolate them from solution, some kind of counterion must be present, and in extracellular environments or saline buffers etc. that would most often be sodium. That said, there are other counterions present in such situations, which will be mixed together as the nucleotide is isolated to bring things to a net neutral charge, and I wouldn't ordinarily think to say "sodium salt of a nucleotide" about something unless it had been synthesized or purified. Wnt (talk) 12:20, 20 May 2018 (UTC)[reply]
Well, you know, an incorrect answer on a multiple choice quiz doesn't necessarily have a specific meaning. In the literature "sodium nucleotide" usually refers to a salt formed by combining sodium with a nucleotide. Looie496 (talk) 15:05, 20 May 2018 (UTC)[reply]
An incorrect answer ("distractor") on a multiple-choice quiz doesn't necessarily have to have any meaning in context, be self-contradictory, or even be actual words at all. After all, they are, by definition, "not correct" for the context. Just off the top of my head[original research?], goofy choices might be added when a test-writer needs one more option but can't think of anything else plausible, as a "freebie" hint for random-guessers who even have a slight idea, as tension-breakers to make students smile when reading a difficult exam, or just to see if they can catch someone who is truely clueless. DMacks (talk) 16:30, 20 May 2018 (UTC)[reply]
Brain wiring
Why is the brain wiring not as optimized as possible? And even 'twisted'? That is, left hemisphere connected to right side of the body and right hemisphere to the left side (more or less)?
Why is the visual cortex quite on the back of the brain, wouldn't the neuronal connection be safer closer to the eyes?
Wouldn't simplicity be a clear evolutionary advantage? Less stuff means less stuff that can go wrong. --Doroletho (talk) 17:22, 20 May 2018 (UTC)[reply]
Our Contralateral brain article discusses some theories about the evolution of this feature. Be careful not to assume that this is something other than the end result of smaller changes. Some of them early on may have had a clearer "reason" with no obvious drawback, and once there became some drawbacks, the cost of getting out of that evolutionary rut was too great at that time. DMacks (talk) 19:01, 20 May 2018 (UTC)[reply]
The answer to "Why didn't evolution find this better way?" is always: there's no chain of incremental changes, leading from one to the other, such that each step is an improvement. —Tamfang (talk) 19:32, 20 May 2018 (UTC)[reply]
Well, not quite always. It's also possible that the existing form is too new for the necessary mutations to have happened (and been selected for) yet. --76.69.47.55 (talk) 06:27, 21 May 2018 (UTC)[reply]
Because evolution works on the basis of "good enough". See argument from poor design; the examples of "suboptimal" design in nature are legion. As long as an organism can survive and reproduce, its traits can make it to the next generation. Traits that are only somewhat suboptimal will only be slowly acted against by selection pressure. It's also difficult for evolution to "go back" and "undo" a bunch of traits to replace them with something "better". If an organism is at a local maximum in the fitness landscape, it's very unlikely for evolutionary pressure to push it "downhill" in order to get to another "peak", even if said peak is higher. The usual outcome instead is gradual tinkering with existing traits, which often leads to exaptation of a trait for something else. --47.146.63.87 (talk) 13:42, 21 May 2018 (UTC)[reply]
Here is a reference on evolution of the optic chiasm - one surprising detail is that some humans have achiasmatic syndrome aka nondecussating retinal-fugal fiber syndrome; they can see but have congenital nystagmus, involuntary horizontal movements of the eye. From this paper it looks like the tracts don't cross over, at least in one case. Curiously, that one says there is "mirror reversality" because the nerves from the side of the eye that should cross over end up aligning with others from the opposite side. But I don't know if that means that the person actually sees the world superimposed with a mirror image or not; I don't think so because the same paper says that gross vision is maintained.
In a broader context I should note that the pineal gland is, in some vertebrates, a dorsal eye. The optic tracts enter the thalamus at the dorsal side. The superior colliculus integrates optic information dorsally in the midbrain just below the thalamus. And the eyes are originally derived from the brain, a dorsal structure. It seems, therefore, that there should be a deep dorsal evolutionary origin for eyes, but I haven't seen a good model for how it would once have worked. Wnt (talk) 14:56, 21 May 2018 (UTC)[reply]
Some book I read decades ago, perhaps by Asimov, speculated that having the right side of the brain connected to the left arm, leg and eye might help you fight an attacker who is to your left and who whacks the left side of your head, rendering the left brain less effective. Seems like that would rarely be an advantage to the wild animal who also have the crossover like it would be to a human fighter. Edison (talk) 17:03, 21 May 2018 (UTC)[reply]
If the attacker is to your left and conks the left side of your head, and the left hemisphere of the brain is impaired as a result more than the right side, then per the writer, the less damaged right hemisphere could direct the left arm to punch him back. “Brain damage” is not always necessarily to the same extent throughout the brain. Please email me if you need further explanation of concepts such as localized injury to brain tissue. . Edison (talk) 03:06, 22 May 2018 (UTC)[reply]
No, I'm afraid Hofhof's objection cannot be that easily dismissed. 1) Only an insanely tiny fraction of TBIs sufficient to create significant brain damage are going to specifically impair just contralateral motor function of the specific extremities needed to defend one's self, while leaving the individual otherwise mostly unharmed (and certainly, able to survive, because the survival part is a precondition of the argument that this is a selected-for pressure). That's just not remotely the way brain injuries work. 2) Weighed against the collective pressures on brain anatomy and neurophysiology, even if there was a selective pressure here, it would not have been sufficient enough to have selective value when balanced against the overall structures/modules which have arisen because of much greater pragmatic benefit. And 3) hemispheric development began weeeeelllll before humans in vertebrate history and is common to many animals which can expect no great incidence of head trauma, much less the sort which would require the creature to thereafter bob and weave around an opponent attacking from a given side. Nor is there a correlation between creatures with greater susceptibility to head trauma and increased hemispheric isolation of motor function.
So yeah, whoever your "expert" was, they were practicing pure folk neurophysiology. It could have been Asimov, frankly. I adored the man, but he came from an earlier era when popular science gurus were expected to comment on a wide array of topics and sometimes found themselves stranded when going out on a limb. And boy did Asimov like to speculate; indeed, that ceaseless wonder at every aspect of the human condition that science could inform upon was part of his charm, and something then-contemporary popular science culture was more tolerant of, thirty to fifty years ago. But today, we know a lot about the selective pressures which are thought likely to have lead to hemispheric physiology, and no serious researcher has ever suggested the theory you discuss above as being anywhere on the map of commonly contemplated selective features for this quite major aspect of brain physiology. Snowlet's rap03:09, 23 May 2018 (UTC)[reply]
OP, I would advise against ever analyzing adaptive fitness through the lens that it needs to move an organism towards more "optimized" or "perfect" form, especially when it comes to neurophysiology. Organisms are only "optimized" in the sense that they are calibrated towards their particular ecological niche, and therefore are more likely to survive in the environment and contexts they are likely to face. But as a more or less per se matter, all useful adaptions have trade-offs, and this most certainly applies to brain structure. The brain (with regard to organisms with developed cerebrums in particular, but also other vertebrates) is also highly modular; it has many different structures which developed under separate (if sometimes overlapping) pressures, and generally controlled by different genes, meaning they sometimes work at cross purposes, competing (in a manner of speaking) at fulfilling the function of their design, as each was arrived at because it conferred some evolutionary advantage in some context. Even if the brain were not modular, it would (in the context of its adaptive value to all vertebrates) still need to find some way to be (to varying extent amongst different species) something of a generalist, because it needs to be able to process unpredictable stimuli and meet a wide variety of practical challenges, and the nature of existence for all organisms (particularly those of great complexity) is that they can't know in advance exactly what problems they will be facing in every instant of their life.
So most brains are highly optimized in the sense that they prepare the specific organism they are a part of to face the challenges that it is likely to face--or more precisely, which its forebearers did in fact face. While at the same time, optimization outside of the terms of context/ecological niche is a more or less meaningless concept. There are some fields of the cognitive sciences which are completely predicated on these principles; for example, with regard to human hebaviour, there is evolutionary psychology which attempts to explain some of our more peculiar and sometimes counter-intuitive-seeming propensities as a product of our genetic heritage (which, unless you are an animist of some sort, you must do if you want to be rational about human nature). According to the general thrust of EP, these "irrational" behaviours are the result of the operation of modules which developed as part of our genetic heritage, and because very little time has passed in evolutionary terms since we became behaviorally modern humans (meaning that we have not "evolved" much in the "mere" 100,000 years or so since), our hunter-gatherer brains still make many decisions which are not yet perfectly adapted to the advantages of our new developed societies/ecological context. So, simply because we have come so far so fast in terms of changes to our environment (social and technological) we sometimes behave in a manner that is not 100% conductive to our own well-being as modern humans, but in a fashion that was quite optimized to our original context as the third chimpanzee. To use a (somewhat inaccurate) metaphor, we have software that is just a little too out-of-date to make perfect use of our hardware, without bugs.
Lastly, your final proposition there deserves special mention, because you are quite right that sometimes the simplest design is the most optimal for an organism, including with regard to its nervous system. So, many species are highly optimized (and highly successful in terms of longevity of the species in a more or less unaltered state for up to hundreds of millions of years or more) to their environment despite having relatively simple brains. But some of their offspring or distant cousins found themselves in contexts where random mutations and adaptive pressures caused them to adopt traits which allowed them to discern between a greater number of stimuli or to adapt to a wider variety of challenges. Then some of the offspring of these organisms (with their brains that were necessarily just slightly more complicated than their forebearers) also went on to even further grow their brain complexity, and so on, and so on. Some of them also occasionally traded back their complexity for simpler designs again, because their environment demanded it (although this happens less frequently for very complex reasons I won't go into here). What you are left with at the end of the day (err, epoch) is is a huge array of different species with greatly varying neuro-complexity (and very different specialization of its structures even among the highly complex varieties), each according to its ecological niche. I hope that helps address some of your questions--feel free to ping if you have follow-ups! Snowlet's rap04:08, 23 May 2018 (UTC)[reply]
According to its article, E. coli "usually...is immobile, and keeps its round shape". How does the thing consume nutrients? I was under the impression (wrongly, apparently) that all amoebae consumed food by surrounding it and basically engulfing it, but that doesn't work if one doesn't move and doesn't deviate from a round shape. The article's almost entirely focused on the amoeba as the source of diseases of various sorts and says almost nothing about the species itself, as if our article on lion talked almost entirely about people getting attacked by lions and basically didn't address the animal's life cycle. Nyttend (talk) 02:48, 21 May 2018 (UTC)[reply]
"Keeps its round shape" is only sort of true, in a "compared to what" sort of way. It does form pseudopods, and is capable of phagocytosis. I have a feeling this may be a bad paraphrase of info here: "Motility: visible only in fresh, unfixed stool specimens. The trophozoite slowly forms a pseudopod, then withdraws it and remains immobile maintaining a round shape. After a few moments, a new pseudopod forms in a new position, and so on. The result is an anarchic, sur place (non-progressive) movement, without a defined direction. In some cases, it is possible to observe the simultaneous, explosive formation of 3-5 small, rounded pseudopods extend simultaneously, but even in this case the amoeba remains within the microscopic field." - Nunh-huh03:12, 21 May 2018 (UTC)[reply]
Unrelated to this discussion, I wonder if there is any source that uses Escherichia coli and Entamoeba coli in the same work. Both of them can be written as E. coli. SSS (talk) 16:03, 21 May 2018 (UTC)[reply]
My mom's hands are often cold during the colder days but warm on warmer days. It makes me ask if there's some people's hands that are never that warm, or rather always dependent on the temperature of the surroundings, no matter what time of year is that? PlanetStar05:11, 21 May 2018 (UTC)[reply]
The fuel pin outer diameter in BWRs is 12.5 mm however, it is 9.5 mm in PWRs, why?
I guess it has to do something with CHF (critical heat flux) but not able to correlate totally.14.139.124.180 (talk) 14:06, 21 May 2018 (UTC)[reply]
How come that radio waves (lower side of the frequency spectrum) can cross walls, light (in the middle) can't, but X-rays (upper side) can cross walls too?
And regarding mechanical waves, why do sound waves can cross walls (somehow), but ultrasound (starting at a certain frequency - don't know which) is blocked? If ultrasound has more energy, shouldn't it be able to cross walls? --Hofhof (talk) 01:05, 22 May 2018 (UTC)[reply]
And this guy says X-rays only partially penetrate walls, and it depends on the density of the wall.[7] And you know from personal experience that reception of radio waves also varies depending on various factors, including the structure of whatever wall you're within, if any. Like if you go through a tunnel and lose the signal. ←Baseball BugsWhat's up, Doc?carrots→ 01:33, 22 May 2018 (UTC)[reply]
The tunnel has a mash of steel, it's not really the walls proper that are blocking the radio waves. But the point it, brick walls block 100% light, a little radio waves, and some x-rays. So, the blocking is not proportional to the wave frequency. Hofhof (talk) 01:49, 22 May 2018 (UTC)[reply]
The radio waves have a very low energy per photon, so they do not interact in quantum ways, instead they interact with electrical and magnetic properties of what it encounters. If there is no iron or steel the magnetic interaction is simplified, and it is more effected by dielectric constant and electric eddy currents. The waves can still penetrate bricks, plaster, and wood, but some will reflect off, and a little will be absorbed. As the frequency rises into the high microwaves, more and more will be absorbed. In the sub-millimeter range there are many molecular absorption bands, which extend into the infrared. With things like bricks and plaster, they are composed of tiny crystals just a bit bigger than the wavelength of light. These will scatter the light, as each time it goes into a crystal or comes out, some light will be reflected, and soon none makes it through. But if you had a thin sliver of brick, you will be able to see some light coming through diffusely. Graeme Bartlett (talk) 07:45, 22 May 2018 (UTC)[reply]
This is why thin metallic (usually aluminium) coatings on mylar plastic film or on glass can be used as filters on camera and telescope lenses to directly view and to photograph the Sun safely. {The poster formerly known as 87.81.230.195} 2.221.82.140 (talk) 17:03, 22 May 2018 (UTC)[reply]
The rule of thumb in linear physics (which includes most common waves) is that everything is a low-pass filter beyond a certain frequency, so that very high frequencies always get blocked by everything. You can expect exotic effects close to resonance frequencies though, and the meaning of "very high" can vary.
For mechanical waves across walls, first of all ultrasound has more energy is a bit misleading. You would not say that "blue light has more energy than red light". Similarly to light, you have more energy per "particle" (phonon) at higher frequencies, but it does not mean that the whole excitation is higher-energy. See Sound_energy_density#Mathematical_definition for the math (v/c is essentially frequency; sound pressure can vary between your typical ultrasound and your typical sound, though).
turmeric with black pepper vs crcumin with piperine
This is a layman's question. The benefits of turmeric are said to be unavailable when consumed raw due to rapid metabolism of curcumin. Curcumin compounded with piperine is said to increase absorption of the former many times over. Do raw turmeric powder/paste mixed with raw black pepper powder provide any considerable beneficial results?
--Skillguru (talk) 09:22, 22 May 2018 (UTC)[reply]
@Count Iblis: That paper makes some very strong statements, and whenever one paper says that thousands are wrong, we should be cautious. To be sure, it is true that curcumin sticks nonspecifically to things and is fluorescent, which can make many false positive results. However, there is at least some indication [8] that curcumin really influences a subject animal. Studies on animal models and patients suggest real effects. The most impressive effect is its effect on liver toxicity from something like an injection of carbon tetrachloride -- see [9] for example, but there are dozens of papers like this on PubMed. Nothing in Figure 1 looks like it is due to nonspecific activity or autofluorescence. To be clear, I'm not making a case here that it is known to be beneficial (or not) for a human, but the results should not all be discarded just because the research has a few known obstacles. Wnt (talk) 14:43, 22 May 2018 (UTC)[reply]
Everything in some way provides something considered a "beneficial result." To ask this question, you must define what a "beneficial result" might be and then define what level of result is considered "considerable." For example, hemlock provides a considerably beneficial result if your goal is suicide. 209.149.113.5 (talk) 15:42, 22 May 2018 (UTC)[reply]
Fat
According to this video on Youtube saturated fat contains only 6 calories per gram instead of the 9 calories which is traditionally stated for fat. Dude sounds like he knows what he's saying. Can anyone prove to me if he is telling the truth? Couldn't find any references myself on this one. Thanks bros. — Preceding unsigned comment added by 177.43.154.145 (talk) 16:17, 22 May 2018 (UTC)[reply]
He says cocoa butter is 6 calories per gram. This site says "there are 248 calories in 1 oz. of cocoa butter" There are 28.35 grams in an ounce, so this works out to 8.7 calories/gram. Pretty close to 9. Why would you believe one site more than the many sites that give an approximation of 9? Seems to be the "dude" needs to present some sources if he wants to be believed, rather than merely making an assertion. - Nunh-huh22:30, 22 May 2018 (UTC)[reply]
Since butter is an emulsion of water in fat, it's reasonable that it's calorie content per gram is somewhat lower than that for pure fat. 202.155.85.18 (talk) 03:34, 23 May 2018 (UTC)[reply]
Actually, it's more like Barry Groves is to healthy dying.... He died of a heart attack in 2013 at the age of 77. - Nunh-huh02:33, 23 May 2018 (UTC)[reply]
The truth on this statement is the ketogenic diet. See the liver as a "metabolic converter", only. When eating sugar, it directly feeds. Depending on the sugar, glucose does immediately, other sugars less fast. In the intestine, carbohydrates were converted to sugars and transferred into the blood, rising the blood sugar level. Sugar addiction, we are already suffering on it. Beginning a ketogenic diet or traveling in a region without availability of convenience food, we feel about 3 day of nearly permanent hunger, not caused by the stomach, but caused by the liver which tries to avoid getting forced into ketosis. The Hay diet (separating fats from carbohydrates) has a similar effect, but returns the body to the sugar addiction. See also the list of diets. A ketogenic diet also requires interrupted by consuming carbohydrates when stopping loosing weight or power when the body turns into an energy saving mode like starvation response when food is not avail. Beginning such diet, diabetes affected people get the problem of controlling the blood sugar levels. Usually drinking more water will be necessary, least to avoid problems on blood and kidneys, also when eating more proteins. With reducing weight and consuming of sugar containing food, sometimes blood sugar levels and blood pressure can more normalize when not caused my other disease or malfunction. A critical overweight can be normalized by such or similar diet. An increase of weight, is such diet usually does not happen, least when walking enough or having sports. A further loose of weight, sometimes requires the HCG diet or Hollywood Diet. This also can be found in the paleolithic diet as refinated sugar did not already exist. About or misunderstanding about sugar and metabolism, read about the Sugar Lie. [11] We are storing sugar, converted into fat. Converting the fat back to sugar as ketones, we feet uncomfortable when not longer being a sugar Junkie and decide for food, not made to keep customer being a sugar junkie. But no one will start such business due loosing customers. --Hans Haase (有问题吗)16:47, 24 May 2018 (UTC)[reply]
May 23
Mass spectrometry
In an ordinary, commercial single quadrupole ICP mass spectrometer (such as an Agilent 7800), what happens to all of the ions that hit the detector? I presume that there must be some mechanism to clear them off, otherwise they'd just build up and eventually ruin the detector. 202.155.85.18 (talk) 09:26, 23 May 2018 (UTC)[reply]
Gunk (the technical term) does build up inside of mass spectrometers, and they do need to be disassembled and cleaned regularly to address this. While many of the ions will grab an electron and dissipate as a gas when the system is vented at various times, plenty of gunk collects on the components after regular use. The components need to be taken out, disassembled, cleaned, and re-assembled. I've not used that specific model, but I suspect the processes are similar for any Mass Spec. The documentation above notes the need to periodically clean the "ion lenses", which IIRC are metal plates that carry an adjustable voltage to allow the ion beam to be focused. This was the most fidly bit in the cleaning process. Source: My first job as a chemist was doing exactly that. It was 22 years ago, so things may have changed a bit, as well. --Jayron3214:04, 23 May 2018 (UTC)[reply]
What's the strongly orange-colored fungus that grows in the Mid Atlantic states?
You do know that "I hadn't heard it before now" is not a synonym for "illogical". The states are located along the middle part of the Atlantic coastline of North America. Thus, mid-Atlantic. There are other places in the world named for the bodies of water they are near, such as the Pacific Northwest, the Eastern Mediterranean, etc. It's more surprising you've never heard of regions of land named after some combination of a direction + body of water. --Jayron3215:48, 23 May 2018 (UTC)[reply]
To be fair to the IP, without specification, to anyone not from the US, Mid-Atlantic would clearly refer to the middle of the Atlantic, as in Mid-Atlantic Ridge. It is a confusing usage. Fgf10 (talk) 21:22, 23 May 2018 (UTC)[reply]
To be fair, slime molds aren't fungi either. But as many people don't recognize the taxonomy here, "orange slimy stuff" is the best we can go on. Of course, if SMW really wanted someone to provide useful answers, he'd supply us with a photograph. --Jayron3215:11, 23 May 2018 (UTC)[reply]
The phone with the photo got water-damaged and always dies while booting even on AC power. It was on the ground, a pretty saturated orange not yellow, not resembling stereotypical mushrooms, mold, lichen or moss (and the last 2 are symbiotes and plant anyway), had a fairly simple shape without hairs or fuzziness and may have only been attached to the ground in the middle. Thickness was multiple millimeters, length and width both over a centimeter but not over a decimeter and at least a few times the thickness. Thanks for correcting my misconception that slime molds were fungi. Sagittarian Milky Way (talk) 16:15, 23 May 2018 (UTC)[reply]
But SMW didn't mention "slimy". If it's slimy, then it's likely to be a slime mould or a cyanobacter (we have many local species of Nostoc, greeny brown, under a generic folk name of "witches' butter" - but slime moulds are uncommon). Here at least, "orange stuff visible on a tree or rock" will be one of the orange lichens, far more likely. Andy Dingley (talk) 16:16, 23 May 2018 (UTC)[reply]
Apollo reentry and "equivalent power" for the heatshield?
Does anyone have an estimate for the equivalent power of the Apollo Command Module heatshield during atmospheric re-entry? Just something rough, in terms of initial kinetic energy + potential energy - final KE + PE (at time of parachute deployment), divided by the duration. How does this compare with a Saturn engine? Andy Dingley (talk) 15:03, 23 May 2018 (UTC)[reply]
How I'd do it: KE+PE in LEO-PE at chute deploymanet/average time for descent to deploymanet of chutes. I'm supposed to be in a meeting so can't actually do that. Greglocock (talk) 22:47, 23 May 2018 (UTC)[reply]
Did the command module actually brake into LEO? I thought it came in with more energy than that. The max would be the entire energy from The orbital distance of the moon, I think. Final KE at chute deployment must be quite small. The problem in any case is to research the mass of the command module at the point it begins is aerobraking, as it will have thrown away a bunch of stuff earlier. The KE being dissipated will be KE= 0.5*mv2. so what was the mass? -Arch dude (talk) 23:37, 23 May 2018 (UTC)[reply]
I don't think they entered LEO on the return, it was a direct burn to re-entry, but I assume that the energies were similar, otherwise they would have done so. It's a limit that Apollo must have had sufficient heatshield to cope with at least LEO's energy. It would be interesting to know what the difference in energy (pre-burn) between the return from the translunar orbit and an LEO orbit would have been - was this best dealt with by the SM engine burning longer, or by a larger heatshield? Andy Dingley (talk) 08:52, 24 May 2018 (UTC)[reply]
It's all about the mass. In general it takes less mass of heat shield than it does of fuel to provide the same braking energy. That's why you use a heat shield at all. Otherwise, the system would have used the rocket all the way down to parachute height. -Arch dude (talk) 20:57, 24 May 2018 (UTC)[reply]
This NASA document suggest that the heat shield was designed to handle a total heating load of between ~7000 and ~37500 BTU, which is (very) roughly the same number of kilojoule, at a maximum heating rate of between 83 and 425 BTU/ft2-second. With a diameter of 12'10", the heat shield would have an area of approximately 130 square feet, meaning the heat shield (very roughly) had a power equivalent of between 10790 kW and 55250 kW. If you by "Saturn engine" refers to the Rocketdyne F-1 used on the first stage of the Saturn LV, that was rated for maximum trust of 7770 kN. One kilowatt is the same as one kilonewton per second, so the heat shield was about 7 times "more powerful" than the F-1 engine. A direct comparison is kind of pointless, but fun to play with the numbers :) WegianWarrior (talk) 21:53, 24 May 2018 (UTC)[reply]
There's something funky with your math/units; I'm pretty sure that saying one kilowatt is the same as one kilonewton per second is incorrect. I think you want a newton-meter per second to get the units to work out.
(Note that if you presume that the heat shield is 7 times more powerful than the F-1 engine, then you get pulped astronauts. Recall that a force of one newton will accelerate a 1 kg mass at one meter per second per second. The Apollo command module had a mass of about 6000 kg, so a thrust of 7770 kN – 7 770 000 N – will impart an acceleration of about 1300 m/s/s, or about 130 g. At seven times that force, you're looking at a deceleration of close to a thousand gees, bringing the returning Apollo capsule to rest relative to the Earth in about...one second. Splat!) TenOfAllTrades(talk) 22:51, 24 May 2018 (UTC)[reply]
In round numbers, the loaded Apollo command module came in at around 5500 kg. Atmospheric entry on a lunar return trajectory was at about 11 km/s. If I haven't lost any powers of 10, that comes out to a kinetic energy of about 300 GJ (gigajoules). Since kinetic energy goes as velocity squared, the remaining kinetic energy of the capsule is negligible for our purposes.
From the start of atmospheric reentry to deploying the drogues takes about 7 minutes on a lunar return trajectory. This NASA document has actual data, showing the acceleration forces felt aboard Apollo 10 during reentry in Figure 4. There was a relatively rapid rise to about 7 gees, followed by more complex acceleration profile during the remainder of the descent; that works out to an average deceleration force of about 2.5 gees. Getting rid of 300 GJ over 7 minutes requires dissipating about 700 MJ/s (700 megawatts).
Most of that energy ends up carried away by the air, not imparted to the heat shield. (Which is fortunate. Back-of-the-envelope, 300 GJ is enough thermal energy to completely vaporize 5 tons of aluminum capsule—4 times over.)
Decelerating at an average of 2.5 gees requires a drag force of about 140 kilonewtons (5500 kg times 25 m/s^2). As noted above, the thrust of one first-stage F-1 was 7770 kN: about 50 times as much. TenOfAllTrades(talk) 01:42, 25 May 2018 (UTC)[reply]
What makes decibels of whistles higher?
Decibels of whistles for referees vary and the max decibels that I found is 127.6 dB.
How does the whistle itself influence the dBs? Wouldn't that be almost 100% dependent on how strongly you blow into it? How does the force of the blowing influence the dB then?--Hofhof (talk) 20:34, 23 May 2018 (UTC)[reply]
See the quite extensive steam whistle for some pointers. A whistle can be thought of as a "pneumatic spring". See Helmholtz resonator. The energy is provided by the air blast, stored in the reservoir by compressing the air slightly, then released. It's energy from the reservoir that makes the sound, not the moving air. Up to a point, the volume is proportional to the blowing velocity. It is very difficult to increase the sound volume past this by blowing harder, because once the reservoir is operating at its peak, then blowing harder and harder just doesn't change this.
Blowing harder may also change the frequency, but this depends on the type of whistle design. Some are optimised to do this (making them almost 'playable'), some to avoid it. Andy Dingley (talk) 21:01, 23 May 2018 (UTC)[reply]
A Decibel abbreviated dB is a ratio on a logarithmic scale and the term 127.6 dB means only "5.012x1012 times as powerful". That usage neglects to explain the power reference (what power is 0 dB?). Sound power levels in decibels are meaningful only when expressed with a suffix to define their reference. For example, the OP might mean dB ref 10−12 W (threshold of hearing), dB(A) (a perceptual frequency-weighted scale) or something else unspecified. DroneB (talk) 11:20, 24 May 2018 (UTC)[reply]
Colin Wilson's Spiderworld
Can someone please tell the correct order of all the parts included in this series ? On net info is incomplete or incorrect at most places. Thanks Jon Ascton (talk)08:06, 25 May 2018 (UTC)[reply]
It is most certainly a tadpole, although very early in its development; you can see the basic morphology from which the torso develops, but the tail lacking any fringe dates this one as a recent hatchling. Its apparent size relative to its level of development is a bit of a confusing factor for me; a more precise location could be instrumental in giving a more precise identification. Right now, my best guess is Rana Temporaria. Snowlet's rap06:48, 24 May 2018 (UTC)[reply]
Sorry for no scale. Also the picture is rather low quality. From observation, our frogspawn appeared to not have gotten past the initial stage. It just disintegrated. I would have expected a tadpole of this size to definitely have some limbs, and appear a lot darker. I suppose i'll have to wait and see. The timing is right and our frogs are Rana temporaria, although appear a lot darker but I think that's down to water algae content. Thanks for your help, Cesdeva(talk)07:48, 24 May 2018 (UTC)[reply]
I agree that the most confusing aspect is the large size relative to development. Some frogs do have tadpoles that can be several times that apparent size very early in the larval stage, but I am scratching my head all the same as there are only so many species extant in England. As to colouring, it can vary considerably between populations in a given species, and even within a given population--although European common frogs are usually a little darker, as you note is typical for your local population in the past. The fact that you describe this specimen as "disintegrating", suggests a possible explanation, though: dead specimens no longer maintain constrained osmotic equilibrium in their tissues and can swell considerably. The integrity of the torso appears substantial in the picture, but as you note, the quality is so-so. Snowlet's rap08:31, 24 May 2018 (UTC)[reply]
It most certainly is not a tadpole. The colour is wrong, the shape of the body is wrong and the tail is wrong (OK otherwise!) It is the larva of a member of the Eristalini a kind of fly, commonly known as hover flies in the UK. The larva is known as a rat-tailed maggot and what appears to be a tail is in fact a breathing tube. Have a look at this image. Richard Avery (talk) 09:54, 24 May 2018 (UTC)[reply]This be the beast
Thanks for the link. It seems the larva is an indicator of poor water quality, which is as I suspected. I added some oxygenating plants a few days ago so we'll see how that goes. Cesdeva(talk)
I stand corrected! (and a little sheepish). I thought there was something wrong with that tail morphology (there's usually at least a little bilateral fringe on the tail/flage, even very early in development), but I just chalked it up to the photo quality or state of the specimen. Thanks for rescuing a gung-ho ID--fascinating larval phase/lifecycle for that clade! Snowlet's rap17:04, 24 May 2018 (UTC)[reply]
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