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May 20

Organic Mechanism Steps

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)

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)

Just to support the structural dispute, doi:10.3762/bjoc.8.172 is an X-ray crystal structure of DMP. DMacks (talk)

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)

@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 S_N1 type reaction. I suppose the isopropanol could lose a proton first and replace the -OAc in an S_N2 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)

I haven't seen literature support for a pre-dissociation (S_N1-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 K_eq 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)

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)

We literally have an article on nucleotides. Plasmic Physics (talk) 11:47, 20 May 2018 (UTC)

The term seems unfamiliar, but I assume that they mean something like ATP disodium salt [1]. 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)

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)

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, 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)

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)

How do you know that it is not optimized? Ruslik_Zero 18:37, 20 May 2018 (UTC)

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)

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)

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)

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)

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)

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)

I don't see how, in the case of a brain damage, it could matter what side was and to what it was connected. Hofhof (talk) 00:51, 22 May 2018 (UTC)

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)

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. Snow ^{let's rap} 03:09, 23 May 2018 (UTC)

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! Snow ^{let's rap} 04:08, 23 May 2018 (UTC)

Mostly sensible, but what does animism have to do with Young Earth creationism? I wouldn't even expect animists to hesitate about evolutionary ideas, though I should admit I don't know their religion. Wnt (talk) 14:04, 24 May 2018 (UTC)

I meant "animist" in the more traditional and broad sense; i.e. as regards a belief that human nature arises from spiritual forces and entities, rather than purely naturalistic mechanisms. I'm afraid I don't follow the young earth creationist reference, as it relates to my comments. Snow ^{let's rap} 08:25, 25 May 2018 (UTC)

@Snow Rise: If we have an article about the broader sense you describe, could you add it to animism (disambiguation)? Thanks. Wnt (talk) 13:25, 25 May 2018 (UTC)

Well, the closest thing we have is the main animism article; that article approaches the concept from three overlapping usages: 1) animism at its broadest sense (any kind of belief in a supernatural force which infuses the physical world and is said to be the ultimate source of life, or thought, or spiritual vitality; as a tautological matter, some of these beliefs are said to be more dualistic than others, but for purposes of the philosophy of cognition, I personally think they all qualify as at least somewhat dualistic--though you will find that article gives voice to opinions which disagree with me on that point), 2) animism as it is utilized as a clinical term in anthropology and some other social sciences to describe a subset of spiritual beliefs, and 3) specific religious traditions which have called themselves "animism" or described themselves as "animistic" (often, but not exclusively, new wave spiritual movements or modern versions of traditional shamanistic beliefs). Each of the three uses converges on a common center, but the second two are each a little more narrow than the usage that precedes it on that short list. My usage is a little dated, but still out there; its just a way of saying "a belief or argument which is inconsistent with a strict naturalistic view", or, put otherwise, any belief or argument which diverges from an explanation predicated in a belief that all things are a part of the natural universe and should (in theory) be explainable purely by physical laws, even if we don't as yet understand all of those laws. Snow ^{let's rap} 23:38, 25 May 2018 (UTC)

I may have been misunderstanding you from the beginning. You weren't suggesting doubt of evolution in general, necessarily, but of the role of genes in psychology, which is (among other things) a more debatable topic. We have the strange phenomenon of "general intelligence" and what, to the non-animist (in your broader sense) must be a very surprising deficit of "criminal genes". Why aren't there races incapable of working mathematics, or families with a mappable locus for committing violent crimes? It is conceivable that there is some middle ground between naturalism and animism where people admit that a natural process leaves the human essence somehow in command of its destiny - "emergent phenomena" being the vague yet perhaps insufficient description often used. Wnt (talk) 14:55, 26 May 2018 (UTC)

May 21

Entamoeba coli

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)

"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-huh 03:12, 21 May 2018 (UTC)

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)

It is inconvenient. [2] - Nunh-huh 04:05, 22 May 2018 (UTC)

Hands are always cold

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? PlanetStar 05:11, 21 May 2018 (UTC)

Although this is borderline asking for "medical advice" -- which we cannot provide (see this page's header), here is a reference from a reliable source: "Cold hands". Mayo Clinic. Mayo Foundation for Medical Education and Research.. —2606:A000:1126:4CA:0:98F2:CFF6:1782 (talk) 06:16, 21 May 2018 (UTC)

Pressurized water reactor and boiling water reactor fuel pin

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)

"CHF" = ? —2606:A000:1126:4CA:0:98F2:CFF6:1782 (talk) 18:19, 21 May 2018 (UTC)

Presumably Critical heat flux (the only relevant topic listed on our CHF page:) DMacks (talk) 19:58, 21 May 2018 (UTC)

"CHF" refdesk trifecta in play! See #What Does Spironolactone have to do with Chronic heart failure that other diuretics doesn't have?. DMacks (talk) 02:29, 22 May 2018 (UTC)

May 22

Types of wave through wall

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)

This guy thinks he has an answer to part of your second question.[3] ←Baseball Bugs ^{What's up, Doc?} carrots→ 01:30, 22 May 2018 (UTC)

And this guy says X-rays only partially penetrate walls, and it depends on the density of the wall.[4] 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 Bugs ^{What's up, Doc?} carrots→ 01:33, 22 May 2018 (UTC)

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)

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)

Sounds very similar to what one of my high school science teachers said - that if you had a sheet of normally-opague metal that was sufficiently thin, it would be translucent. ←Baseball Bugs ^{What's up, Doc?} carrots→ 08:43, 22 May 2018 (UTC)

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)

• 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.

GB above has answered the radio vs. light vs. X-rays question, but here are a few more links for the many modes of EM-matter interactions, depending on which frequency (or energy or wavelength) the photon has compared to matter: close to molecular bond energy, close to Zeeman effect spin coupling, above atomic radius, below atomic radius.

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).

Finally, wall-ultrasound interaction can get tricky because we still have resonance effects, not at the molecular level but with the micro-structure of the material (example of ultrasound spectroscopy). Tigraan^{Click here to contact me} 09:12, 22 May 2018 (UTC)

VOR/DME approaches

What are (or were) some real-life examples of VOR/DME (or TACAN) approaches where (1) the DME arc extends all the way to the missed approach point, and/or (2) the approach course begins on one VOR radial and then sidesteps onto another radial from the same VOR station (without crossing it)? 2601:646:8A00:A0B3:EDA1:77AF:46A8:7B5 (talk) 06:44, 22 May 2018 (UTC)

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)

No. Count Iblis (talk) 11:00, 22 May 2018 (UTC)

@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 [5] 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 [6] 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)

In my opinion this question is a request for medical advice. Looie496 (talk) 13:16, 22 May 2018 (UTC)

Can the question be answered completely without providing a diagnosis, prognosis, or treatment advice? Yes. It's just a request for information about a combination of substances, not one bit related to diagnosis, prognosis, or treatment of anything. Nyttend (talk) 00:25, 23 May 2018 (UTC)

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)

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)

edit: he says it at 5 mins 15 seconds into the video — Preceding unsigned comment added by 177.43.154.145 (talk) 16:20, 22 May 2018 (UTC)

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-huh 22:30, 22 May 2018 (UTC)

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)

• The dude thinks that smoking is good for you, even arguing that "smoking causes cancer" is a conspiracy to make money. I'd call him a quack, but it's more accurate to say that Barry Groves is to healthy living what neo-Nazis are to Judaism. Ian.thomson (talk) 00:56, 23 May 2018 (UTC)

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-huh 02:33, 23 May 2018 (UTC)

All mimsy were the Barry Groves... and remindful of this item:[7] ←Baseball Bugs ^{What's up, Doc?} carrots→ 03:33, 23 May 2018 (UTC)

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. [8] 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)

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)

The ions will be neutralised by electrons, react with the detector or turn into a gas. Things need to be cleaned inside it. There is a vacuum pump to remove what turns into a gas, and the detector should be changed in the yearly maintenance. see https://www.agilent.com/cs/library/technicaloverviews/public/5991-9342EN-cost-of-ownership-icp-ms-technicaloverview.pdf page 4. Graeme Bartlett (talk) 10:02, 23 May 2018 (UTC)

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. --Jayron32 14:04, 23 May 2018 (UTC)

What's the strongly orange-colored fungus that grows in the Mid Atlantic states?

Sagittarian Milky Way (talk) 14:11, 23 May 2018 (UTC)

Most likely Fuligo septica, also called the "dog vomit slime mold". It isn't confined to the Mid Atlantic states, but is found worldwide. --Jayron32 14:52, 23 May 2018 (UTC)

That's a terrestrial fungus, you're not going to find that in the middle of the Atlantic, like the OP is asking about. 131.251.254.154 (talk) 14:57, 23 May 2018 (UTC)

Mid-Atlantic (United States) is terrestrial. ←Baseball Bugs ^{What's up, Doc?} carrots→ 15:06, 23 May 2018 (UTC)

What an illogical and confusing name! Fair enough, I stand corrected. 131.251.254.154 (talk) 15:38, 23 May 2018 (UTC)

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. --Jayron32 15:48, 23 May 2018 (UTC)

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)

To be fair to Jayron, logic would tell you that their are no states in the middle of the Atlantic Ocean. ←Baseball Bugs ^{What's up, Doc?} carrots→ 01:49, 24 May 2018 (UTC)

• No idea, I'm in the UK (similar climate). Our brightly orange coloured one isn't simply a fungus though, but a lichen. Xanthoria parietina, Caloplaca marina or C. thallincola are all commonly seen (and fairly easily distinguished). Andy Dingley (talk) 15:08, 23 May 2018 (UTC)

  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. --Jayron32 15:11, 23 May 2018 (UTC)

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)

I didn't pick one to see if the underside had furrows like mushrooms. Sagittarian Milky Way (talk) 16:24, 23 May 2018 (UTC)

Sagittarian Milky Way, they were fungi. See Slime mold#Taxonomy: They were originally represented by the subkingdom Gymnomycota in the Fungi kingdom and included the defunct phyla Myxomycota, Acrasiomycota, and Labyrinthulomycota. Nyttend (talk) 20:46, 23 May 2018 (UTC)

• 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)

Chicken of the woods is often strikingly orange and common enough in the UK (don't know about Mid Atlantic states). --catslash (talk) 22:59, 23 May 2018 (UTC)

Chicken of the woods might be it, or a related species. Sagittarian Milky Way (talk) 23:56, 23 May 2018 (UTC)

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)

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)

• 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)

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)

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)

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)

Thanks, that's saved me digging out a bunch of numbers. Andy Dingley (talk) 22:25, 24 May 2018 (UTC)

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 kilonewton-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)

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)

I thought it was carried away as a result of ablation. That's not just the air, but also part of the heat shield itself being converted to gas (and plasma: it's really hot) and being carried away, with its heat, into the air. -Arch dude (talk) 21:53, 25 May 2018 (UTC)

That's a common misconception; the ablation of the heat shield does dissipate some of the energy, but only a relatively small fraction. (Again, the kinetic energy shed by the capsule would be sufficient to vaporize the heat shield many times over.) Essentially, the blunt reentry vehicle piles up a bunch of air in front of the vessel; the air is compressed and heated, and spills around and away from the capsule, taking the heat with it. The heat shield is mostly dealing with radiant heating from this compressed shock layer, rather than direct frictional heating. The shadowgraphs in Atmospheric entry#History are relevant. TenOfAllTrades(talk) 01:33, 26 May 2018 (UTC)

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)

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)

It's very simple. The whistles go woo woo! --47.146.63.87 (talk) 07:52, 24 May 2018 (UTC)

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)

The OP specifically asked about a whistle that is blown into, such as those used by referees and railway train managers. It takes a certain amount of energy to get the pea in the whistle moving, and this appears to be near the maximum amount of airflow that a person can blow. Consequently, there cannot be much variation in the intensity of the sound. Akld guy (talk) 20:17, 25 May 2018 (UTC)

Weird pond creature

What kind of pond creature is this?

Pond creature

It was wriggling about in the water.

Location: England

Cesdeva ^(talk) 23:42, 23 May 2018 (UTC)

• Looks like a tadpole of some sort. --Jayron32 02:04, 24 May 2018 (UTC)

• Unfortunately, there's no scale, although the netting mesh suggests that it's small. I Google-imaged "tadpole" and a few photos came up that look kind of like it. ←Baseball Bugs ^{What's up, Doc?} carrots→ 03:02, 24 May 2018 (UTC)

• 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. Snow ^{let's rap} 06:48, 24 May 2018 (UTC)

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)

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. Snow ^{let's rap} 08:31, 24 May 2018 (UTC)

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)

This be the beast

Thank you. That's extraordinary, I never knew hover flies had such interesting larvae. Cesdeva ^(talk) 10:09, 24 May 2018 (UTC)

As it happens, I took a picture of what I think was hoverfly near the pond the other day.

Possibly a hoverfly

Cesdeva ^(talk) 10:21, 24 May 2018 (UTC)

Of course, Wikipedia has an article on... everything! —2606:A000:1126:4CA:0:98F2:CFF6:1782 (talk) 13:27, 24 May 2018 (UTC)

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)

Eristalis interruptus, I would venture. (Though I will stop short of insistence for obvious reasons. ;) Snow ^{let's rap} 17:32, 24 May 2018 (UTC)

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! Snow ^{let's rap} 17:04, 24 May 2018 (UTC)

May 25

Laurel-Yanny followup

The following discussion is closed. Please do not modify it. Subsequent comments should be made on the appropriate discussion page. No further edits should be made to this discussion.

---

There was a question recently about the "Laurel-Yanny" thing which has since been archived. This is a followup FYI: This guy, the voice behind the "Laurel-Yanny" thing, says the reason people are hearing different things is a result of different frequencies of their listening devices.[9] ←Baseball Bugs ^{What's up, Doc?} carrots→ 05:37, 25 May 2018 (UTC)

The discussion above is closed. Please do not modify it. Subsequent comments should be made on the appropriate discussion page. No further edits should be made to this discussion.

Car engine = kW/hp calculation

What is the correct kW/hp or hp/kW for car engines??

I've seen some sources online saying

1kW = 1.3hp

1kW = 1.341hp

1hp - 0.74kW

1hp = 0.7476kW

and at Toyota_Celica#Fifth_generation_(T180;_1989–1993) I saw this:

77 kW / 103 hp

What is the correct calculation for hp-to-kW and kW-to-hp, especially for articles on vehicles sold in Australia, New Zealand and South Africa where kW is widely used?

I want to ensure things are accurate, but have no idea! --Chelston-temp-1 (talk) 12:25, 25 May 2018 (UTC)

For what it's worth, our article on horsepower shows the origin of several similar-but-not-identical figures, so at least you can see where the different conversion factors come from. I can't tell you which one is correct for your particular situation, mind you, but maybe that information can get you started in the right direction.... TenOfAllTrades(talk) 13:02, 25 May 2018 (UTC)

No hp conversion is correct(or wrong indeed). Hp is not a standardized unit of measure. Use kW if being precise matters. Use hp if it doesn't (in ads, for example).31.4.131.201 (talk) 14:11, 26 May 2018 (UTC)

• There are two issues here - how many W in a hp? (746 is pretty much universal, especially today) and then how is "car engine power" to be measured? In particular, is this the output power of the engine, that engine power less the power needed to drive the essential ancillaries (oil pump, water pump, alternator etc.), or the power at the wheels? There is also the issue of how the engine is run when determining this - how long it has to sustain such a power, what air temperature it does it at, etc. These measurement differences make a lot more difference to the numbers than the small (and now mostly historical) variations in W/hp. Andy Dingley (talk) 14:25, 26 May 2018 (UTC)

Compressing the H and O of one liter of water

If we separate the H and O from 1 l of water into the two gases (H2 and O2), and then try to compress each one in a bottle of 1/2 l: how difficult would it be? If the matter is the same, why would they separated need more space? --Doroletho (talk) 13:12, 25 May 2018 (UTC)

This is a standard unit conversion or dimensional analysis type of problem. Convert the volume of water to the number of moles (using density and molecular weight) of the H2 and O2, then you can try using the ideal gas law determine the gas pressure of that number of moles when compressed to your volume at whatever temperature you like. I suspect the pressure will be enormous, probably enough that it's not an "ideal gas", but it will git you a hint of how different gases (typical density: 25 L/mole at room temp and atmospheric pressure) and liquids (18 mL/mole for water) are at the molecular level. DMacks (talk) 13:21, 25 May 2018 (UTC)

• Weirdly enough, there seems to be no good sources online for density-vs-pressure diagrams for O2.

I would guess that the real question behind OP's question is why H2O is liquid at room temperature/pressure when neither H2 nor O2 is; or equivalently, how come that the H2O molecule can be packed much more densely than H2 or O2 at room TP; or, yet equivalently, how come intermolecular forces between H2O molecules are much stronger than between H2 or O2 molecules. One answer to the latter is that water is a polar molecule and hydrogen bonds stabilize the liquid form (from our article, A polar molecule in general has a higher boiling point [than a nonpolar molecule], because the dipole–dipole interaction between polar molecules results in stronger intermolecular attractions.). However, I am not sure it is the only answer - it would imply that for any atomic species A, B that can combine into a nonpolar molecule AxBy, if A2 and B2 are gaseous species in a certain condition of temperature and pressure then AxBy also is, which seems quite a strong assertion. Off the top of my head I could find no counterexample: only two simple molecules fit the "gaseous single-atoms refs but liquid molecule" bill, water and nitrogen dioxide, both of which are polar. Tigraan^{Click here to contact me} 15:16, 25 May 2018 (UTC)

Just to give the details of the calculation that DMacks suggested -- an atom of H₂O weighs about 18 atomic mass units (16 for the O and 1 each for the two Hs). So 1 liter = 1000 grams of water contains 1000/18 = 55.5 moles of water molecules. After splitting them, you have 55.5 moles of oxygen atoms which forms 27.8 moles of diatomic oxygen molecules. Similarly, you have 111 moles of hydrogen atoms which forms 55.5 moles of hydrogen molecules. One mole of any ideal gas occupies 22.4 liters, so the 55.5 moles of hydrogen would occupy 1243 liters at standard temperature and pressure. Therefore it would need to be compressed to 2486 atmospheres of pressure to fit in 0.5 liters. The oxygen, having only half as many molecules, would need to be compressed to 1243 atmospheres. CodeTalker (talk) 17:02, 25 May 2018 (UTC)

Quantum spin

Can the spin of an electron be approximated by viewing an electron to be shaped like a spindle torus that is also knotted, where helical rotation occurs about the locus of the torus? Plasmic Physics (talk) 14:08, 25 May 2018 (UTC)

Electrons don't spin. The concept of spin is used to approximate the concept of a magnetic moment and magnetic deflection. Unlike real items that spin, electrons can spin in only two directions and the energy, whatever energy you want to discuss, of the spin is limited to very specific values. 209.149.113.5 (talk) 15:20, 25 May 2018 (UTC)

Per 209; electron spin is not "spin" in a classical sense. Spin (physics) refers to an intrinsic property which behaves like angular momentum, but it is using the term "spin" as an analogy, not to say that the electron actually spins. To say that a subatomic particle has "spin" is akin to saying quarks have color. It's a word that we can use to represent a phenomenon, which closely matches the mathematics necessary to account for that phenomenon, but it's not actually that thing. --Jayron32 17:23, 25 May 2018 (UTC)

Well, come on, it doesn't just "behave like" angular momentum. It is angular momentum. Angular momentum is a conserved quantity. If you send right-circularly-polarized light through a medium that converts it to left-circularly-polarized light, the angular momentum has to go somewhere; presumably there is a torque on the medium that a sufficiently sensitive experiment can measure. --Trovatore (talk) 01:48, 26 May 2018 (UTC)

Yes, but the thing is, you're not supposed to think about the election as a spinning ball, because that introduces so sorts of problems that we needn't get into here. I wasn't referring to the fact that elections didn't have angular momentum, just that you can't visualize what the thing is that is spinning. There's no thing to spin in the way that, say, the Earth spins around it's axis. It's just that the electron, whatever it is, has intrinsic angular momentum. As soon as you ask "how do I picture it spinning in a way that makes sense by analogy to an shape I could make" the answer is "shut up and calculate." Or another way: there is no adequate image you could conceive. There is just the angular momentum and The electron has it.--Jayron32 03:02, 26 May 2018 (UTC)

Yes, but what actually makes the above description inadequate? Plasmic Physics (talk) 03:18, 26 May 2018 (UTC)

I know precisely that 'spin' is used as a abstract concept in quantum mechanics. What I am asking is if the electron actually spins, but not about an axis per se. Plasmic Physics (talk) 22:28, 25 May 2018 (UTC)

One wonders if an electron is like a ball at all.... Abductive (reasoning) 01:10, 26 May 2018 (UTC)

Electron and other QM spins are very often described with spin vectors, which more or less imply the spin has a somewhat discernable direction. The degree to which these vectors are known is limited, among other things, by the requirement that Planck-based quantized units of angular momentum be transferred in any interaction. The weird part is that if you start reading about nuclear magnetic resonance, suddenly spin starts to become incredibly real - for example, see the illustration in spin echo, where the spin magnetization of individual nuclei seems to be realigned precisely. I still don't claim to fully understand how this is consistent with the it's-just-QM stuff we hear elsewhere (and above). Wnt (talk) 01:42, 26 May 2018 (UTC)

What makes a ruminant's milk more dangerous than human breastmilk that it needs to be pasteurized before consumption?

Raw, unpasteurized milk can carry dangerous bacteria such as Salmonella, E. coli, and Listeria, which are responsible for causing numerous foodborne illnesses. How do the bacteria get inside the ruminant's milk in the first place? Perhaps, the bacteria find their way in the milk supply, because the farm is a dirty place, and a cow's feces can wind up in the milk supply? Or does the milk directly from the cow contain those bacteria similar to how human mothers carry bacteria and viruses in their own milk supply? If the bacteria/viruses are in the mother's milk supply, then will the calf become sick from drinking the cow's milk? If the calf is fed through a bottle unpasteurized cow's milk, then can the calf still become sick? Or do humans become sick because they have more dedicate stomachs than calves do and cannot destroy the bacteria and thus need pasteurization to kill the bacteria for them? SSS (talk) 15:16, 25 May 2018 (UTC)

Our article on pasteurization suggests that the danger in raw milk came from contaminants in the milk supply chain: "Milk is an excellent medium for microbial growth, and when stored at ambient temperature bacteria and other pathogens soon proliferate ... Prior to industrialization, dairy cows were kept in urban areas to limit the time between milk production and consumption hence the risk of disease transmission via raw milk was reduced. As urban densities increased and supply chains lengthened to the distance from country to city, raw milk (often days old) became recognized as a source of disease." Gandalf61 (talk) 15:30, 25 May 2018 (UTC)

As above; if we drank bovine milk straight from the cow like a calf does, microbial proliferation wouldn't be an issue. But simple refrigeration isn't enough to retard bacterial growth in such a nutrient-rich environment, so in the time it takes to package, transport and sell that raw milk, any bacteria that have been introduced to the milk grow like they're in a Petri dish. NorthBySouthBaranof (talk) 15:35, 25 May 2018 (UTC)

It would be helpful if you provided a ref for how fast bacteria grow in properly refrigerated raw cow’s milk. That is contrary to what I remember from my high school science course before quick analysis of DNA existed . Edison (talk) 17:19, 25 May 2018 (UTC)

I tried Googling, but articles on the time course of bacterial growth in raw cow milk under refrigeration name scores of bacteria types without clarifying which cause illness in human consumers and which are innocuous. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC520874/ Says that in 24 hours some microbe species actually disappeared while others proliferated. Another article said that in zealously sanitized dairy barns the bad bacteria showed up in the milk in higher concentrations that when some normal bacteria found on the teat survive. Edison (talk) 17:35, 25 May 2018 (UTC)

In times when wet nurses might be infected with syphilis, a better solution was proposed: that infants whose mothers could not nurse them should suckle directly from goats. Healthy animals, clean udders, no supply chain, no bacterial disease. On the other hand, when human milk is used by hospitals now, part of the function of human milk banks is to check that no nasties have accumulated - I believe they do this by freezing and pasteurising. Carbon Caryatid (talk) 22:53, 25 May 2018 (UTC)

What does it mean “patient K”?

I found the same question in other forum and nobody answered it but it's interesting for me: What does it mean "patient K"? I googled it to find an answer, but I found a lot of results without explanation to this term. What is "patient K"? "Clinical Example: Patient K., 54 years old, during 15 years has been suffering from type II DM (Diabetes Mellitus) with periodic phenomena of decompensation... (Obesity and Diabetes Mellitus - Book)" --93.126.116.89 (talk) 22:02, 25 May 2018 (UTC)

They referred to a patient using a letter instead of their real name. Alternatively, that's just the initial of their first or last name. Ian.thomson (talk) 22:05, 25 May 2018 (UTC)

Yep. You can go searching medical case reports and you'll find every letter used this way. Someguy1221 (talk) 03:16, 26 May 2018 (UTC)

One of the more famous examples being HM (patient). --47.146.63.87 (talk) 05:19, 26 May 2018 (UTC)

May 26

Sorry, the question was incomplete hence confusing, am reputting it

Semi-automatic Pistols

Though I have been familiar with guns since kindergarten days, I have some doubt regarding semi-automatic handguns. Most semi-automatic pistols I have handled till now have same basic things: you put a loaded magazine in the handle, pull the slide-bolt back fullback and release it - causing the first cartridge to go into breech. The gun is ready to fire - the blow-back will throw out the used cartridge and on it's way back also bring a fresh one from the magazine. But my grandfather once that certain .25s (perhaps he was talking about Czechoslovakia brand), or perhaps all .25 calibre pistols. Is that right ?  Jon Ascton  (talk) 16:13, 26 May 2018 (UTC)

What did your grandfather say about .25 calibre pistols? Your question seems incomplete at the moment. Tevildo (talk) 18:29, 26 May 2018 (UTC)

Before you finish asking your question, I'm going to guess the answer: your grandfather's .25 was not a simple semi-automatic, but it was a double-action pistol where the trigger pull reset part of the gun. CZ 45 comes to mind as such a pistol in .25. Since the CZ 50 is also like this, and that's a .32, I'm guessing it's just the manufacturer, and not the calibre. There are ordinary .25 semi-automatics. Someguy1221 (talk) 19:00, 26 May 2018 (UTC)

May 27

Semi-automatic Pistols

Though I have been familiar with guns since kindergarten days, I have some doubt regarding semi-automatic handguns. Most semi-automatic pistols I have handled till now have same basic things: you put a loaded magazine in the handle, pull the slide-bolt back fullback and release it - causing the first cartridge to go into breech. The gun is ready to fire - the blow-back will throw out the used cartridge and on it's way back also bring a fresh one from the magazine. But my grandfather once said that certain .25s, don't require the necessary ceremony of pulling back the boltslide - the loading up of the magazine itself is enough to cause the magazine's first cartridge to pass into the breech : causing the gun ready for firing. (perhaps he was talking about Czechoslovakia brand), or perhaps all .25 calibre pistols. Is that right ?  Jon Ascton  (talk) 16:13, 26 May 2018 (UTC)

What did your grandfather say about .25 calibre pistols? Your question seems incomplete at the moment. Tevildo (talk) 18:29, 26 May 2018 (UTC)

Before you finish asking your question, I'm going to guess the answer: your grandfather's .25 was not a simple semi-automatic, but it was a double-action pistol where the trigger pull reset part of the gun. CZ 45 comes to mind as such a pistol in .25. Since the CZ 50 is also like this, and that's a .32, I'm guessing it's just the manufacturer, and not the calibre. There are ordinary .25 semi-automatics. Someguy1221 (talk) 19:00, 26 May 2018 (UTC) — Preceding unsigned comment added by 223.185.35.136 (talk)