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.
I'm trying to understand why the heat of fusion of chlorine (3.2 kJ/mol) is higher than that of sodium (2.6 kJ/mol).
Chlorine has a melting point of 172 K and I gather this means that the intermolecular forces holding the lattice of chlorine molecules together are relatively weak.
Sodium has a melting point of 372 K so the interatomic forces holding a lattice of sodium atoms together are stronger.
Now, at each element's melting point, why does it take more energy to disrupt the solid chlorine lattice and complete the transformation to its liquid structure than is the case for the sodium lattice? (In both cases I understand that some short term structural order is preserved.) Sandbh (talk) 01:34, 16 April 2016 (UTC)[reply]
You will have to look at the liquids that are produced. Presumably liquid sodium is still held together by metallic bonds, whereas liquid chlorine only has van der Waals forces holding it together. You could look at the heat of vaporization (which for sodium is much greater than for chlorine) and specific heat between these points as well to see the whole story. Chlorine molecules have a more awkward shape and so could be more difficult to solidify than the spherical sodium atoms, and so that will affect the melting point too. Graeme Bartlett (talk) 05:46, 16 April 2016 (UTC)[reply]
Heat of fusion only takes into account enthalpy portions of the transitions. Melting point is based on the ratio of enthalpy and entropy. In this case, while the heat of fusion for chlorine is higher, the discrepancy of melting points can ONLY be explained by entropy. Wikipedia's article on entropy of fusion covers how melting point works as a relationship between entropy and enthalpy. --Jayron3223:30, 16 April 2016 (UTC)[reply]
Tx for the responses. I see that the heat of vaporisation figures are 99 for sodium, and 10.2 for chlorine. So the heat of fusion for Na is merely 2.5% of its heat of vaporisation whereas for chlorine it's a whopping 30%. So when sodium melts there seems to be hardly any bond disruption whereas there must be more of this action when solid chlorine melts. To eliminate any complications associated with comparing monatomic sodium with diatomic chlorine, I see that the heat of fusion of xenon (2.3) and radon (2.9) are comparable or greater than that of sodium (2.6). For Xe and Rn the heat of fusion values (12.6; 16) are about 18% of the heat of vaporisation figures. The only explanation that comes to mind is that, for some reason, the clusters of xenon and radon atoms in their liquid forms are smaller than the clusters of sodium atoms, which may be about 100 atoms a piece, in liquid sodium. Smaller clusters would then presumably require more interatomic bonds to be broken. Pure guess work on my part. Sandbh (talk) 23:52, 17 April 2016 (UTC)[reply]
Stainless Steel Wire AISI 302/304... Magnetic in spring temper.
What does "magnetic in spring temper" mean? Does it mean that 302/304 stainless steel is not normally attracted by magnets, but in its spring temper condition it is? Or that it actually emits a magnetic field and attracts other materials in its spring temper condition?Johnson&Johnson&Son (talk) 12:11, 16 April 2016 (UTC)[reply]
The way I read that line: this alloy is manufactured and tempered specifically for use as a spring; and after it is tempered, the resulting product is ferromagnetic. Other (non-spring) products manufactured from the same alloy or same stock material might not include the tempering process and therefore might not be magnetized. Tempering involves application of heat, and that's a fantastic way to activate or inactivate ferromagnetism, depending on the ambient conditions during the heat treatment procedure.
Most variations of stainless steelare non-magnetic - which is a little unintuitive, considering that steel is mostly made of iron... so the fact that these stainless steel spring wires are tempered in some fashion that magnetizes them is worth calling out.
Thanks, guys. I'm asking because I brought some 304 spring temper steel wires, and some of them are attracted by magnets and some are not (more accurately it's not binary, there's various levels of how strong the attractions is). Could this be that some of the wires are actually not in spring temper but just regular 304 stainless steel wires? Johnson&Johnson&Son (talk) 04:01, 17 April 2016 (UTC)[reply]
Anything's possible - I certainly don't know what you've actually got in your inventory or where it came from. I think it's more probable that the material is all the same alloy; but the magnetism is an unintentional side-effect. The manufacturer is not trying to magnetize the metal during heat treatment, but it can occur, largely depending on ambient magnetic conditions during the heating. The manufacturer probably doesn't want or need to control those conditions, so the amount of magnetization may vary between batches. Even if the springs all started out with identical magnetization, it's ferromagnetism, which can be easily lost during normal handling just by, say, banging the material against the packaging during shipment, or being in close proximity to a differently-aligned magnetic field, or being stored at elevated temperatures, and so on. Nimur (talk) 05:18, 17 April 2016 (UTC)[reply]
April 17
Torch beam question
Does the beam from a torch exert a force (obviously a minuscule one) backwards on the torch? If so, does that mean that there must be mass ejected in the light beam, and, if so, where does that mass come from? Does the torch get lighter as a result of expulsion of mass? 86.151.118.252 (talk) 01:09, 17 April 2016 (UTC)[reply]
Note for my fellow Americans: in British English they use "torch" for what we call a "flashlight". Anyway, answers: a) yes, it exerts radiation pressure. b) mass and energy are the same thing, so the answer is yes. It is true that photons have no rest mass. c) Yes, very slightly so, because of the loss of the stored energy contained in the batteries (or whatever the power source is). I recommend these videos for learning more about mass and energy in physics: [2][3] (and really, every video on that channel is great). --71.110.8.102 (talk) 02:05, 17 April 2016 (UTC)[reply]
@StuRat: Really? I was thinking of India, Pakistan, Hong Kong, Rhodesia, Palestine, Malaya, Singapore, Sri Lanka, Falkland Islands, Mauritius, Malta, Jamaica, Trinidad, Barbados, British Virgin Islands, Guyana, Fiji, Vanuatu, Tuvalu, Solomon Islands, Papua New Guinea. This list has been thrown together quickly because I don't want to waste any more time on this, but you get the meaning. Akld guy (talk) 00:56, 20 April 2016 (UTC)[reply]
Yes, chemical potential energy is expelled. The mass is reduced in the torch as the energy expelled is expelled. Charging the battery adds mass as well. It's much too small to be observed as the mass of a charged battery is not measurably different from a discharged battery even though we know there is a difference, --DHeyward (talk) 08:44, 17 April 2016 (UTC)[reply]
Just to pique your brain a little bit harder than usual: the theory of relativity doesn't actually formally prove the conservation of energy; it just provides a bunch of new coordinate-change equations that help relate energy and position.
So, even if we admit that the emitted light does carry both energy and momentum, this is not in itself proof of a mass-decrease in the flashlight. That mass-decrease depends entirely on an unrelated and unproven physical concept - conservation of energy. Nearly every experiment validates this principle; nearly every intelligent and educated scientist believes this principle; but it is not actually a requirement of special- or general- relativity. For the record: I also believe that energy and mass are normally conserved, at least on average, and I believe there is no reason to doubt this premise in normal circumstances.
But the story does not end there: science does not rest on "strong beliefs." We need complete theories, and we need experimental evidence to validate those theories. This is called the scientific method.
In fact, it remains an open question whether we could ever construct some metaphorical flashlight that emits energy and momentum but loses no mass. This would be symmetry breaking; more specifically, it would be a break in "T-symmetry", or "time symmetry." To my knowledge, no reputable scientist has ever seen this happen; but there are lots of theorists who study it, because it would have incredible consequences that can help us describe the evolution of our entire universe.
Here is an article from none other than Symmetry Magazine, a joint publication of SLAC and Fermilab: Fermilab and symmetry breaking (2008). It helps explain why the 2008 Nobel Prize in Physics was awarded to a trio - (they worked in groups of three) - of very smart physicists, who worked through the very subtle theoretical consequences of CP-violation. This is different physics; but in terms of my intuition, it superficially appears equally un-physical as a flashlight that can emit energy and momentum without losing mass. These scientists propose a violation of a conservation law. Yet, this theory was Nobel-worthy: the math does not forbid it. The fact is, you're here as a carbonic bag full of salt water born on a cluster of used-up stardust, instead of existing only as a bunch of thermal-equilibrium-in-a-vacuum. This in itselfproves that there must have been some condition in the past in which some conservation law was violated, and we still have an incomplete explanation about the how- and why-.
To keep us on the right side of the physics/metaphysics line, weak anthropic principle might be a better candidate for Nimur's last link than the cogito. Thought without material existence is not a priori impossible. Tevildo (talk) 16:06, 17 April 2016 (UTC)[reply]
Sure, I can agree with your statement! I meant to suggest that thought implies thermal non-equilibrium, and non-equilibrium implies imperfect symmetry. I assert that these statements are distinct from the less logically-closed statement, thought implies material existence! You can read Descartes' own impressions - for example, he is republished in English in Great Books of the Western World - and in my reading, his position seems to be that of the more restrictive, almost solipsistic stance - material existence may occur, though it is largely superfluous; but thought must occur! The man had a lot to say on the scientific method, and his work predates the academic distinction between "science" and "philosophy," so we can only imagine what he might have thought about the way more modern thinkers have formulated anthropic principle! Nimur (talk) 20:15, 17 April 2016 (UTC)[reply]
The Symmetry article is interesting, but seems less approachable than our own Cabibbo–Kobayashi–Maskawa matrix article. It seems to differ in at least one regard - it says that the CKM matrix predicted three generations of quarks, while our article makes it sound like it was written to account for them. Wnt (talk) 21:46, 17 April 2016 (UTC)[reply]
Nimur's post is completely wrong. He seems to have confused time-reflection symmetry with time-translation symmetry. The former is called T symmetry and is dual to CP symmetry. The latter is the symmetry associated with energy conservation in Noether's theorem. They are not the same thing.
Any theory defined by a special-relativistic Lagrangian must conserve energy by Noether's theorem. Unitarity implies conservation of energy. A form of energy conservation follows from the Bianchi identities of general relativity. -- BenRG (talk) 01:21, 18 April 2016 (UTC)[reply]
Sir, as many regular readers of this reference desk may know, there is a fascinating history of individuals who would like to tell me that I am completely wrong. I will completely admit that I am sometimes wrong, and sometimes I am even completely wrong, but in this particular instance, I feel that you are weakening your position when you allege that everything I wrote was "completely wrong." Perhaps I wrote unclearly; or perhaps in the spirit of writing toward a general audience I may have elided some subtle detail, but I do not believe - in this instance - that my post was "completely wrong."
There is a part of me that wishes to call out "[citation needed]" and have you present your case using a reliable encyclopedic resource outside of a Wikipedia article. I'm fairly sure that I know how to find such resources for myself, but we have many readers who don't find particle physics particularly accessible.
So, instead of fruitlessly debating whether I am completely mistaken, I feel that it would be more productive if we and the other readers of this reference desk spent our time reading and referencing what some very smart scientists have written on these topics, distilled into a format that is a little bit more accessible to the generally-interested reader. In that spirit, here are a few items from the very same journal:
Symmetry, a user-friendly introduction to the topic.
If you should ever find yourself in my neighborhood, I'd be very happy to join you for a visit to the local particle accelerator, and we can ask a scientist to clarify any of the more uncertain points. If I am wrong, I would very much appreciate a correction of my error.
We clash frequently because you frequently post about things you don't understand. I would get equally frustrated with anyone else who did that (I am equally frustrated with StuRat). There's nothing wrong with reading about symmetries in Wikipedia and science magazines and getting confused about two different symmetries with the word "time" in them. If you'd opened a new thread asking whether energy conservation might be violated because CP is violated and CP is dual to T, I'd have been happy to explain that, no, they're unrelated because they involve different symmetries of time. That's a good use of the ref desk. But when you post your misunderstanding as a reply to someone else's question, that's different. It contributes negative value to the ref desk because it distracts from better answers, especially when it's as long as all the other answers put together, as your posts tend to be. I don't want to make you or anyone angry. But every time you do this, I have to decide whether to let it go or try to limit the damage.
When I say completely wrong, I don't mean 100% wrong on the facts. On a true-false test, it's just as hard to get everything wrong as to get everything right. If you don't know anything, you will score about 50%. The information content of the answers is minimal at 50%. That's closer to what I mean by wrong.
Again, there's nothing wrong with being a beginner in some subjects. The problem is that you don't seem to know which subjects those are. -- BenRG (talk) 19:18, 18 April 2016 (UTC)[reply]
Well you attempted to correct him, but you did so in a way that was also hard (for me) to follow. I understand what you mean when you say time reversal and time translation are two different types of symmetry, and I understand what you mean when you say Unitarity implies conservation of energy. I'm just not so sure how those statements apply to Nimur's original statement. If he struck out this bit --'more specifically, it would be a break in "T-symmetry", or "time symmetry."'-- would you still object to the rest? I mean the CP bit may then be off-topic, but not to my eye saying anything literally incorrect, just perhaps less useful... I mean is Noether's theorem really part of Relativity? Or is that an outside finding? Perhaps are you talking past eachother on the 'unproven' bit? E.g. some people think formal proofs of necessary implications from good models constitute scientific proof, while others may demand something more empirical. But then these ultra-empiricists should abandon the term "proof" to the mathematicians, and only speak of evidence. Anyway, I kinda like it when you two argue. You're both smart people and and some of our best respondents, so it's way more informative than most arguments here. And all of us would do well to try to stick to what we're good at ;) SemanticMantis (talk) 22:10, 18 April 2016 (UTC)[reply]
Note that light has no rest mass but it contains relativistic mass, i.e. energy. If you look up photon you can get a figure for the momentum. Also note that photons carry angular momentum, so in theory you can screw something in with a torch ... it just isn't very much (and neither is the mass). The use of light pressure for solar sails is well known, and is the basis for stabilizing the Kepler telescope; and is proposed in stuff like this. And for every action there is a reaction, as far as anyone has ever found. (Possible violation is being considered as one explanation for Emdrive, but few believe that works at all, let alone that it is truly a reactionless drive) Wnt (talk) 21:37, 17 April 2016 (UTC)[reply]
Limits of human cognition: smallest pixel size/broadest range of colors
Does it make sense to produce screens with smaller and smaller pixels, and more and more colors? Will we reach a point (sorry for the pun) when the human eye cannot see any difference anymore in size/color palette of a dot? --Scicurious (talk) 17:55, 17 April 2016 (UTC)[reply]
Actually you'd most likely need less. You'd need a higher resolution i.e. more total pixels ("dots") which is a different thing. Nil Einne (talk) 23:16, 17 April 2016 (UTC)[reply]
You might be mixing up dots per inch with Display_resolution in pixels. So: say I have an image at 500x500 px. If I display it at a size of 1x1 inch, then I have 500 DPI, and it looks sharp. If I display it at 100x100 inches, it has 5 DPI, and looks chunky, unless I stand really far away. So changing the projection size changes the DPI while holding the resolution constant. For a movie, they have far less DPI than you normally use on your home computer. This is because nobody needs to stand 2 feet in front of the movie screen and be able to read 11 pt font. You need to think about both DPI and resolution (and viewing distance, and lots of other things) to understand how an image will look. SemanticMantis (talk) 14:04, 18 April 2016 (UTC)[reply]
Also, I believe a movie shown on any device requires less resolution than a still, because the mind averages out moving pixels, while you can make them out more precisely if you look closely at a still for an extended period of time. StuRat (talk) 14:27, 18 April 2016 (UTC)[reply]
For resolution, the problem with talking in terms of pixels is that the apparent size of a pixel depends on how far away it is. The maximum resolution of human vision is generally considered to be on the order of one arc-second -- 1/3600 of a degree. To convert that to pixel size it is necessary to specify the distance from the viewer to the screen. Looie496 (talk) 21:44, 17 April 2016 (UTC)[reply]
As in its able to undergo elastic deformation at very high stresses. It's not fluid though, it's like some sort of hard jelly. I think it's called vitreous humour but I want to know what gives it this property at a molecular level. 2A02:C7D:B907:6D00:D185:96E9:64E3:36EB (talk) 23:30, 17 April 2016 (UTC)[reply]
In mechanics, a "high yield stress" means that the physical object or material remains elastic under high stress loads, and does not undergo irreversible (plastic) deformations. The eye indeed has to retain its shape and structural integrity to be able to function properly. Saccadic loads on an eye can be quite high, eyeball reaching angular velocity of a few hundreds of degrees per second in a few tens of milliseconds. The elastic properties of the eyeball, AFAIK, are mostly due to the collagen and other fibers in the sclera; these two wiki articles are probably the best place to start. For the mechanics of the eyeball, the best place to start is probably the classical paper by David Robinson, here. There are newer papers on eyeball mechanics, but this one is very well worth reading. If you are interested in neuroscience (and neuropathology) of eye movement, I suggest the Leigh and Zee book. Hope this helps. --Dr Dima (talk) 16:59, 18 April 2016 (UTC)[reply]
If you mean for "small production runs", then it really depends on a lot of factors. If you need literally one circuit board and have access to a CNC machine, it will probably be quicker to use that. But if you need 20 boards, it might be quicker to print all 20 and etch them in one go than to mill 20 boards on the CNC machine. Secondly, depending how "automatic" your CNC machine is, starting the run and letting it go "overnight" for example, to mill 20 baords will be a lot "quicker" for you (counting only your labor time) as compared to the time and effort required to set up a chemical etching batch and the clean up etc involved, even if the end result will finish "sooner", so which do you prefer? Vespine (talk) 02:21, 18 April 2016 (UTC)[reply]
Just thought of another significant factor to consider is that chemical etching will not drill your board for you. So if you have a lot of through-hole components, manual drilling can be very time consuming and also introduce a significant chance of making a "mistake" potentially wrecking a board. Presuming the CNC machine can also drill the holes, but I'm pretty sure that's almost a given. Vespine (talk) 03:52, 18 April 2016 (UTC)[reply]
Just in the last year 3D printing of multi-layer circuit boards has got good enough to be used for fast prototyping or small runs and one can buy machines to do it. Dmcq (talk) 11:26, 18 April 2016 (UTC)[reply]
When using Windows and your computer crashes and you have to reboot:
When it comes to the screen where you choose to logon or restart or shutdown, should you restart so it shuts down properly and restarts again, or just logon? Thanks. Anna Frodesiak (talk) 08:11, 18 April 2016 (UTC)[reply]
It actually depends on what caused the computer to crash in the first place. Sometimes a proper restart is beneficial, while in other circumstances it doesn't matter. 81.132.106.10 (talk) 09:55, 18 April 2016 (UTC)[reply]
Newer versions of Windows (XP and after) recover better so that logoff and log on clean up a lot. But if in doubt, reboot, because Windows probably needs a reboot twice a month anyway to sort out installs and other problems. Graeme Bartlett (talk) 09:59, 18 April 2016 (UTC)[reply]
@Anna Frodesiak: for future questions, the computing, rather than the science desk might be the better place to ask such questions.
@Anna Frodesiak:, when staring an operating system, serives are started an open files like databases or logfiles. When not shuting down properly, these files are not finished in wirting and the filesystem needs to synchronize all copes of it's tables of contents. Windows writes a copy of it's configuration, called the registry when logging on. In the start procetude, immedialtely after die BIOS, Windows listens for a key like F8 oder the spacebar. It allows the user to boot using the last known good configuration. This is the recent copy taken after the last logon. When updates were or other software was installed, those settings were lost, but the files are still stored on the drive. A resinstall of that software fixes any problems, if the installer works propperly. Upgrades may be a problem, due an old configuration ist applied to the new file versions. When using an autologon on windows, the last known good configuration is not possible, due being overwritten in the start procedure. --Hans Haase (有问题吗)22:05, 20 April 2016 (UTC)[reply]
Continuous flow of electric current
I could get why the flow of current exist only for a short time as said in the video Principles of Electricity when we connect two different beakers that have metal strips immersed in them using a wire.The reason is the electrons from the zinc electrode goes through the wire to the copper electrode.But I couldn't get why there is a continuous flow of current when the beakers are joined together and why the electrodes(zinc and copper) become negatively and positively charged.Could anyone help me.JUSTIN JOHNS (talk) 09:01, 18 April 2016 (UTC)[reply]
Recall that when the zinc strip first entered the acid (at 6:01 in the Principles of Electricity video) some zinc atoms went into the solution, leaving their electrons behind so the zinc gained a certain negative charge (more so than the copper strip which being "less negative than" is the same as "positive relative to" the zinc). The flow of electrons stops when electrical balance is reached (at 6:18) where the solution is more positive than the zinc. However when the beakers are joined, the solution around the zinc receives electrons from the solution around the copper. The continuous flow of electrons from zinc to copper is exactly matched by a continuous flow of electrons through the solution in the opposite direction.
The linked video reflects its date, which was the end of WW2, when it teaches the Bohr model of the atom and mentions "the 92 known chemical elements" that seem to conclude with Uranium (number 92). In fact Neptunium (number 93) had just been isolated in 1944 and Plutonium (number 94) had been isolated in 1940, but wartime secrecy prevented its anouncement until 1948.
The video is not specific about the "chemical solution" involved, in fact a variety of soluble salts, acids or bases dissolved in water give an electrically conducting solution that works as an electrolyte; nor does it explain that copper, zinc or other metal electrodes will be negative or positive relative to one another depending on their relative electronegativities. AllBestFaith (talk) 11:11, 18 April 2016 (UTC)[reply]
Could you explain a little bit more about "The continuous flow of electrons from zinc to copper is exactly matched by a continuous flow of electrons through the solution in the opposite direction." as you have told.I couldn't really get that sentence.JUSTIN JOHNS (talk) 11:16, 18 April 2016 (UTC)[reply]
Your video is so out of date that it is leading you down the wrong track completely. It is now generally accepted that there is no flow of electrons through a wire when an electric current passes along it: it is the charge which flows, not the sub-atomic particles. If you want to know what electricity is and how it works, look at something up to date. 81.132.106.10 (talk) 11:50, 18 April 2016 (UTC)[reply]
Please ignore the above comment. Electric current really is a flow of subatomic particles and this view hasn't changed since 1945. There is nothing wrong with the video, and it even states that its picture of the Bohr model is only a symbol and not what an atom really looks like. --Heron (talk) 19:47, 18 April 2016 (UTC)[reply]
It's not that the electrons travel fast. It's that the movement of one near the end of a conductor displaces an adjacent one, which displaces an adjacent one, etc, etc. The effect is that an electron at the far end is displaced very rapidly. The movement of each individual electron is quite slow. Kind of like the water in a garden hose. When the tap is turned on, water flows out immediately but the water at the tap takes a few seconds till it flows through. Akld guy (talk) 09:06, 19 April 2016 (UTC)[reply]
The internal voltage would not be external, so the included battery / cell provides the energy for the current. However this will not last forever as the chemical energy will be drained. Another way is to have a continuously variable magnetic field threading through the circuit. Unfortunately we cannot make a magnetic field that increases forever, so it is much more common to use a variable field and get alternating current. Graeme Bartlett (talk) 09:40, 19 April 2016 (UTC)[reply]
Do you mean to say that the current will last only for a few seconds since it stops when the all the electrons from zinc rod are transfered to the copper rod?Can we make the process continue forever by using a salt bridge or any other solution?JUSTIN JOHNS (talk) 09:53, 19 April 2016 (UTC)[reply]
A zinc battery may last for quite a few days until all the zinc is dissolved. If you want it to keep going you need a continuous supply of material. This can happen in a fuel cell. A fuel cell could use hydrogen and oxygen to make electricity and water. Graeme Bartlett (talk) 10:38, 19 April 2016 (UTC)[reply]
The reason why it seems like so little happens when an EMF is applied to an open circuit is that it takes a really, really small movement of charge to make a big difference in voltage. How much exactly depends on capacitance, but let's put it this way: one mole of electrons, as might be generated from a molecular-weight's worth of grams of some substance giving up or accepting one electron, contains a faraday unit of charge (Faraday constant), i.e. more than 100,000 Coulombs. And the largest usual value for a capacitor, according to our article, is about 1 mF = 1 mC of charge moved / volt of difference. Electrochemical reactions typically are on the order of a volt, so that means that with good technology you might make a system where you can move 1/100,000,000 of a coulomb of charge before the voltage that creates puts a stop to it, or maybe consume about one millionth of a gram of some material with MW 100. However, there are no capacitors described in this circuit, and so we're looking at parasitic capacitance, less than picofarads, which is to say, a billion times less than that. So unless I fouled up in my math/logic (very possible) I'm seeing we usually expect something on the order of a million billionth of a gram of the battery's substance to get used up in order to create enough of a charge difference to prevent any more from reacting. Wnt (talk) 11:30, 19 April 2016 (UTC)[reply]
Maybe a useful analogy is a metal pole. If you poke on something with the metal pole, you know that the far end would not put any pressure on it unless the metal atoms were being pressed together by the force of your thrust. But you certainly can't *see* the compression; and what's more, you have no real idea how much the pole compresses per force applied, yet it has no practical effect on how much force you put on the far end unless it's practically a wet spaghetti noodle. Wnt (talk) 11:35, 19 April 2016 (UTC)[reply]
The video Principles of Electricity did not point to the impedance or internal resistor of a power source. Batteries do not contain supraconductors. Also the chemical process in the battery is limitted. Depending on the load, the voltage of the source dropps. On a constant load the voltage also keeps constant while the source delivers energy. During this time a continuous flow of electric current is present. It changes when to load is beeing changed or the battery gets empty. --Hans Haase (有问题吗)22:54, 20 April 2016 (UTC)[reply]
Why aren't there fungi that are sexually transmitted?
Parasites, viruses, and bacteria seem to be the main agents of STDs. What about fungi? Why aren't there fungi that are sexually transmitted? 140.254.77.156 (talk) 17:25, 18 April 2016 (UTC)[reply]
This is pretty much semantic. You can get lice from someone else's towel, or a cold from kissing your girlfriend. Most things like C. albicans can be sexually transmitted, but they are not exclusively so, nor primarily treated as if the partner may also need treatment. I.e, chaste virgins can still have yeast infections. μηδείς (talk) 21:05, 20 April 2016 (UTC)[reply]
Raising chickens
If you put one rooster with ten hens in a coop, then would they reproduce? Can you safely put two or more roosters in one coop, or will they become aggressive and territorial? 140.254.77.156 (talk) 17:40, 18 April 2016 (UTC)[reply]
You need to be careful putting a stranger rooster with an established group of hens. They sometimes gang up on him and attack - thought to be reason behind the phrase "hen-pecked". I would strongly advise against putting 2 roosters together - They will almost certainly fight, perhaps fatally. DrChrissy(talk)17:46, 18 April 2016 (UTC)[reply]
Some roosters might get along, others might not. No simple answers.I don't think this is something that there are generally applicable answers for. There's just far too much lore and science of chicken rearing to cover in a short post, but I'll sketch out some ideas and provide some refs that will help. For the breeding - it depends on how happy they are, what their lodgings are, what time of year it is, all sorts of things. For roosters fighting - it depends a lot on how much space is available (to roost, to nest, to forage), and likely what breed. Lots of other factors too (age at introduction, time spent in coop, etc.) Some chickens are more territorial than others. If you want to raise chickens, I suggest they start by reading a book, something like this [4]. Also you can read and post at a chicken-specific forum, like this one [5], or this subreddit [6]. Here [7] is the WikiHow category on chickens, and here [8] is a wikibook on raising chickens, both of those together will be a decent (free) primer, but raising chickens is also something that just requires some practice and experimentation to get good at. Finally I've WP:OR seen at many multiple rooster set ups in back yards; it can be done without aggression if there is enough space and you have the right breeds. SemanticMantis (talk) 18:34, 18 April 2016 (UTC)[reply]
How hard is it to change fields within engineering as a graduate? For example if your original major was in civil but your thesis was related to biomedical but you now work in civil engineering project management whilst volunteering for a mental health charity. How hard would it be to get into biomedical engineering then? 2A02:C7D:B907:6D00:A568:CD48:3581:1FB1 (talk) 20:22, 18 April 2016 (UTC)[reply]
It depends, particularly given your "as a graduate" caveat. First, how much do the two disciplines have in common? For example, here's the current plan of study for a B.S. in civil engineering from my college. Note that the majority of the coursework for junior and senior years are prefixed "CE". Someone changing over from electrical engineering would have none of those courses in their regular plan of study . Even the "technical electives" probably wouldn't permit crossover from one to the other (similarly, your "civil engineer with a thesis in biomed" is highly suspect, even as a thought experiement). "As a graduate", though, makes for a different question. If you're talking career, then it's a matter of "can you pass an interview?" The precise prerequisites are as varied as the jobs in question, and much of the matter is now a matter of your abilities as a candidate rather than your paper qualifications. Plenty of people are working in engineering fields for which they do not have the specific engineering degree. — Lomn20:53, 18 April 2016 (UTC)[reply]
In the U.S., Engineers generally need to pass two exams to be fully practicing engineers: the general Fundamentals of Engineering Examination, passed shortly after one graduates with an engineering degree from college (university), and a second Principles and Practice of Engineering Examination which is specific to the engineering discipline you are working in. Hypothetically, one could (on their own) learn what is needed to pass a second PPE exam, and simply take the second exam to be qualified to work in the new discipline, I suppose. I'm not sure how common or feasible that is, generally you're employed in a specific field, and work as an unlicensed "apprentice" before taking the PPE exam, since your on-the-job training generally prepares you for taking the PPE. --Jayron3201:06, 19 April 2016 (UTC)[reply]
Yeah, the relevance of professional engineering licensure is highly dependent on both field and role, and "unlicensed apprentice" misstates the nature of a large portion of engineering work. The distinction is (within the US, at least) one of whether you are certified to sign and seal documents for engineering work that does not involve interstate commerce. Lack of licensure does not prohibit one from performing the work, nor does it prohibit one from signing and sealing in cases where the work is interstate in nature (see engineering licensure in the US with regard to automotive and other applications). So no, the FE/PE is not a general requirement to be a fully practicing engineer, but rather a potential requirement for a narrowly-tailored area. — Lomn15:41, 19 April 2016 (UTC)[reply]
Easy. YOU are what matters. Not whichever papers you chose at uni. I've designed straw processing gear, crankshafts, undersea monitoring systems, steering systems, yacht hulls, electronic controllers, and every bit on the dirty side of cars. And buildings. Greglocock (talk) 03:55, 19 April 2016 (UTC)[reply]
Absolutely. We could also try extracting brains and testicles from trolls for the same purpose, but I fear the yield would be disappointing. Greglocock (talk) 03:16, 19 April 2016 (UTC)[reply]
Stopping to reflect for a moment, this could be the basis of a revolution for Wikipedia. Jimbo could set up a section within the WMF to market troll bile - and not just any troll bile, but Grade A Encylcopedic Troll Bile, the bile built on the sum of human knowledge. Profits from the sale of this ultra-rare product could be use to provide 5-star holidays for deserving Wikipedians. Bile production could always be increased to meet demand by showing trolls diffs of article improvements, and Wikipedia trolls should be a particularly rich source. EdChem (talk) 08:00, 19 April 2016 (UTC)[reply]
It certainly would do nothing for the energy shortage - liposuction is a surgical process, and all of the technology involved is likely to consume more energy that you could get from the fat removed. 81.132.106.10 (talk) 11:12, 19 April 2016 (UTC)[reply]
Body mass v O2
In general, do animals(of the same species) of a greater body mass use more oxygen (and excrete more CO2) than those of a lesser body mass?--178.99.232.11 (talk) 00:45, 19 April 2016 (UTC)[reply]
Why do Sodium cation (as well as cautions of all other alkali metals) have higher second ionisation enthalpy when compared to the first ionisation enthalpy of noble gases, though both have same electronic configuration, i.e. M+1 cation and ground state noble gases have similar electronic configuration? Eg: IE2 of Na is 4562kJ/mol while IE1 of Ne is 2080.7kJ/mol.
Sodium has a higher charge on its nucleus compared to neon. And to take a second electron off sodium, you have to pull it away from a Na2+ ion, which is harder than separating it from Ne1+. Graeme Bartlett (talk) 07:38, 19 April 2016 (UTC)[reply]
The sodium cation has a higher effective nuclear charge than the neon atom, thus a greater Coulombic attraction to the outermost electrons and a smaller radius. This greater attraction must be overcome in the second ionization, which will thus require greater energy. EdChem (talk) 08:02, 19 April 2016 (UTC)[reply]
What did DSPs like AT&T DSP1 (1979), Altamira DX-1 (1980s) TMS32010 (1983), AT&T DSP16A (1980s), Motorola 56000 (1986) cost like 2 years or so after their introduction? Would they or the NEC µPD7720 been capable of processing realtime Trellis encoding using a 3.3 kHz bandwidth? What would a suitable A/D + D/A cost at the same time, assuming a required 26.4 kHz sps? Bytesock (talk) 16:06, 19 April 2016 (UTC)[reply]
The TMS was of the order of a hundred bucks, in 1986, in the UK, from memory. I don't know what trellis encoding is and don't care to find out. Greglocock (talk) 01:57, 20 April 2016 (UTC)[reply]
If a healthy young person with good nutrition suffers an occasional broken bone, will that tend to help keep calcium levels in bones higher?(Not just in the bones that were broken, but others, such as vertebrate and so on.)I was thinking that after a break, hormones might be released encouraging calcium throughout the skeleton. 144.35.45.57 (talk) 16:17, 19 April 2016 (UTC)[reply]
Why do Neisseria gonorrheae and Chlamydia trachomatis infect together?
I've read that people who get gonorrhea also get infected by chlamydia. Why do those diseases and agents go together? Is there a relationship between the two types of bacteria? 140.254.77.233 (talk) 17:36, 19 April 2016 (UTC)[reply]
I will leave it for others to answer as to whether having one disease makes one more vulnerable to infection with the other. However, note that if transmission by both are caused by the same behavior, you would expect a correlation from that alone. For example; smoking, alcoholism, and drug abuse are often correlated because the same risk-taking behavior (in order to alter one's mood) are present in all cases. StuRat (talk) 17:51, 19 April 2016 (UTC)[reply]
Sorry no ref, and sorry if this is TMI, but: If the genital skin or mucous membrane is compromised in any way (e.g. a lesion or open sore), then there is a direct route into the bloodstream for another infection. So a chancre (a classic symptom of syphilis) would logically increase the risk of acquiring e.g. chlamydia. Carbon Caryatid (talk) 18:45, 19 April 2016 (UTC)[reply]
To further what the previous poster wrote the HIV#Origins article has this section: Specific proposed high-risk transmission channels, allowing the virus to adapt to humans and spread throughout the society, depend on the proposed timing of the animal-to-human crossing. Genetic studies of the virus suggest that the most recent common ancestor of the HIV-1 M group dates back to circa 1910.[1] Proponents of this dating link the HIV epidemic with the emergence of colonialism and growth of large colonial African cities, leading to social changes, including a higher degree of sexual promiscuity, the spread of prostitution, and the concomitant high frequency of genital ulcer diseases (such as syphilis) in nascent colonial cities.[2] While transmission rates of HIV during vaginal intercourse are typically low, they are increased many fold if one of the partners suffers from a sexually transmitted infection resulting in genital ulcers. Early 1900s colonial cities were notable due to their high prevalence of prostitution and genital ulcers to the degree that as of 1928 as many as 45% of female residents of eastern Leopoldville were thought to have been prostitutes and as of 1933 around 15% of all residents of the same city were infected by one of the forms of syphilis.[2]
Thus correlating statistics but not necessarily causal, may come from opening up infection pathways or weakening the immune defense. So the population may first experience syphilis, HIV and say TBC in that order.
I see, so they just look for temperature differences, and assume that means moisture. Seems rather iffy, as things like a hot water pipe may be hotter than the surrounding area whether they have a leak or not. StuRat (talk) 23:17, 19 April 2016 (UTC)[reply]
Yes, Stu. They're scammers selling this stuff to some poor idiots. So next time you have a water leak make sure the plumber rips your home apart until they find the hidden leak.--TMCk (talk) 00:49, 20 April 2016 (UTC)[reply]
Is there any scientific way to detect hidden mould? Toxic mould should be a worry for many households. If only there existed a machine that detected all known allergens! Sandman1142 (talk) 12:26, 20 April 2016 (UTC)[reply]
I know I can smell it, so a trained mold-sniffing dog ought to be much better at it. Of course, there would be health risks for the dog. StuRat (talk) 17:34, 20 April 2016 (UTC)[reply]
What line coding do modern harddiscs use?
Is it still magnetic S-N N-S polarity reversal and the pulse that it causes which is then coded according to some scheme that is used in modern harddiscs? And what coding scheme is used? ie line codes. Because MFM and RLL are most likely no longer used for that purpose.. Bytesock (talk) 21:17, 19 April 2016 (UTC)[reply]
Well, social worker is a protected title in England - one has to have a recognized professional qualification and be registered with the Health and Care Professions Council, see here for some more info. A support worker does not have to have the qualifications and level of registration, and is likely to be lower paid, work longer and more anti-social hours, and be more likely to be assaulted in the course of their duties. DuncanHill (talk) 22:45, 19 April 2016 (UTC)[reply]
Is there a *guaranteed* way to ensure that a person who already got an orchiectomy *doesn't* have *any* extra testicles?
Biology comes with few guarantees. After all, the extra testicle might (astronomically unlikely) be located in a teratoma or a parasitic twin, in a place where you would not expect to find it, and where it does not release sperm to the outside world. The person might also have a condition that prevents testosterone production, in which case you wouldn't find that hormone in blood work. (AFAIR there's also a lower limit of sensitivity because it can be produced elsewhere) Also other markers like INSL3 ([9] may mention more, but I haven't looked through it carefully) This combination of circumstances seems unlikely but in biology there can always be some exception. Wnt (talk) 00:17, 20 April 2016 (UTC)[reply]
Hey, you wanted to ensure and that is one way to be sure. This is the Trump method of ensuring there aren't any hidden sneak testicles — he'll make there be no more testicles. Just wait till approx. thermal equilibrium and maintain the same till any reactions proceed to completion.. Sagittarian Milky Way (talk) 01:42, 20 April 2016 (UTC)[reply]
Come on, I was attempting humor more than political expression. It's a very silly topic (hidden sneak testicles). I'll keep political mentions out of the science desk though. (I can still mention anthropogenic global warming in an unbothersome manner, right? That's only political if you don't believe the consequences of the laws of physics) Sagittarian Milky Way (talk) 22:13, 20 April 2016 (UTC)[reply]
A pelvic MRI would likely locate any extra undescended testicles. EvergreenFir(talk) Please {{re}} 06
58, 20 April 2016 (UTC)
Only if you have a half decent technician looking at the results and they don't make a mistake. Even then, I would be reluctant to talk about guarantees particularly considering stuff like Wnt mentioned and the fact that the OP's history suggests by guarantee they mean they want 100% rather than a very very low likelihood of error. For a lot of it, the chance that the testis will actually produce functioning sperm that will be able to impregnate someone without medical assistance would seem to be very, very, very slim although I'd still be reluctant to talk about guarantees. I'm not even sure you could get some sort of written or implied guarantee from a medical professional since it's a fairly weird request but in any case, what that's likely to mean is they have a medical malpractice provider or whatever who'd provide you money if their guarantee failed. (Presuming the guarantee actually meant something.) Nil Einne (talk) 10:16, 20 April 2016 (UTC)[reply]
April 20
Why did "clean coal" turn out to be so slow and expensive to develop?
I understand that there are serious unknowns about carbon sequestration and "clean coal". But I have to admit - when I first heard of the idea, I assumed someone would have an existing coal plant, drill a deep hole (and frack it), set up a pump to compress the exhaust and drive it underground ... and see what happened. At least you would smell no pollution today. So why didn't this zero-generation version of the process happen? Wnt (talk) 00:03, 20 April 2016 (UTC)[reply]
There's been some concern in recent years about Teflon-based nonstick pots and pans, specifically with regard to the possible health effects of perfluorooctanoic acid (PFOA). In response, some people are returning to stainless steel.
But stainless has a severe sticking problem when new. To make it usable, one suggestion is to "season" the pot. You get it hot and add a bit of some high-smoke-point vegetable oil, swirl it around, let it cool, then wipe it out with paper towels rather than wash it. The oil leaves a residue on the pot, sort of a hard plastic, and now it's much less sticky.
The thing is, though, that seasoning is made of something. What, exactly? Does it contain, say, polycyclic aromatic hydrocarbons (PAHs)? Has anyone done a study comparing the possible effects of PFOA with whatever the more-whole-foodsy "seasoning" is made of? --Trovatore (talk) 05:54, 20 April 2016 (UTC)[reply]
Wait, what? Seasoning is usually only discussed for cast-iron cookware. Our article also mentions carbon steel, but outside of woks I don't think that's very commonly used. Stainless doesn't really take the polymerization layer because it's non-porous. See e.g. this thread [10]. I mean, sure, I guess you can do it to stainless steel, I just highly doubt the efficacy and that you're actually getting much of a persistent film. As for the new stainless being stickier when new - maybe you're just polishing your pots over a few uses so that they get smoother? But back to the question: the idea of seasoning is to cross-link and polymerize the oil. I cannot find anything scholarly on the health effects of this film. This [11] patent says that in addition to the polymer film, there is magnetiteblack oxide in/below the seasoning layer. The one thing I've heard recently about cast-iron cookware is the health benefits, e.g. here [12] and the lucky iron fish. Finally, PAH seem to only form in low-oxygen scenarios. So as long as you're seasoning in normal conditions, I don't think you'll be creating them from cooking oils. SemanticMantis (talk) 14:30, 20 April 2016 (UTC)[reply]
Hmm, well, the interblags seem to think you can do it. See for example here and search for the reply by "cheflars". I tried it and it worked. Admittedly it wasn't a well-controlled experiment, because that wasn't the only thing I changed — I also used less butter and lower heat. I'll try the seasoned pan with high heat and more butter just to see what happens. --Trovatore (talk) 18:13, 20 April 2016 (UTC)[reply]
Don't know about the salt's role in it (see your source) but one point is, to my knowledge, to prevent mineral and other deposits to build up as those add to the stickyness in all types of cookware.--TMCk (talk) 18:27, 20 April 2016 (UTC)[reply]
Oh, @Trovatore: I get it now, thanks. That person calls it "quick season", I think to differentiate it from what we do to cast iron. That method seems to be intended as a limited use "seasoning", which will need to be reapplied every few uses, in stark contrast to the hard shiny layer on my cast iron, which can't be done in a few minutes, and can last indefinitely with proper care use. So while you can do a similar thing to "season" stainless steal, it's rather different effect. SemanticMantis (talk) 18:50, 20 April 2016 (UTC)[reply]
OK, just tried it. I'd call it mostly a success. With the egg going into the soup of bubbling butter (with garlic and habanero slices there before the egg, of course), the egg white bubbled the way I remember it doing back when the pan was unbearably sticky. It came out with a little more difficulty than with the lower heat, but still I was able to get it out without breaking the yolk, which I never could pre-seasoning. Then cleanup without soap was also a little more challenging than the lower-heat trials, but I did manage.
Not claiming this is valid science, but taking the above observations together with the visual appearance of the film, I'm reasonably convinced. --Trovatore (talk) 18:44, 20 April 2016 (UTC)[reply]
Extra iron has health benefits for people who are iron-deficient, but it can be detrimental to the health of normal people, especially middle aged men and post menopausal women. Older people are advised to avoid using cast iron pots and definitely not to use iron supplements. [13]CodeTalker (talk) 16:53, 20 April 2016 (UTC)[reply]
You're right, the source doesn't specifically recommend against excess iron, it just shows that excess iron can cause bone loss. For more specific recommendations against iron supplementation, see [14], [15], [16]. CodeTalker (talk) 19:32, 20 April 2016 (UTC)[reply]
Restriction of supplemental intake makes of course sense but I was wondering about the "avoid cast iron pots" advise. How much iron would be absorbed by the food under normal cooking conditions?--TMCk (talk) 19:46, 20 April 2016 (UTC)[reply]
This article [17] references a 1991 study in Journal of Food Science that showed that spaghetti sauce cooked in cast iron absorbed 2 mg of iron per 100 g of sauce, and applesauce absorbed 6 mg. Given that 100 g is a pretty small serving and that the daily recommended allowance of iron for men is 8 mg, this seems fairly significant. CodeTalker (talk) 20:28, 20 April 2016 (UTC)[reply]
@CodeTalker: and @TracyMcClark and --TMCk: That result is not typical of cooking general things in cast iron, and that is even mentioned in the blurb linked. In more detail: tomato sauce is acidic, and will both break down the seasoning on the pan as well as etch the iron. Also, it is reported that the tomato sauce becomes darker colored than it would in e.g. stainless steel. For this reason, the general advice is to not cook tomatoes, lemon juice, vinegar, or anything else acidic in cast iron cookware. E.g. here [18] they say to "avoid overly acidic foods in our cast irons. On the same token, it’s best not to deglaze a cast iron with vinegar or wine". SemanticMantis (talk) 20:59, 20 April 2016 (UTC)[reply]
1) Ceramic coatings can provide excellent non-stick surfaces with no need to season. They are scratch resistant, but can crack.
2) This issue only comes up when cooking at high temperature, as in frying.[citation needed] Since this is unhealthy anyway, I've decided to cook at lower temperatures, such as boiling water. For example, I don't fry salmon, I boil it in soup. While I made this change for health reasons, a side benefit is that the pot is much easier to clean than a frying pan. StuRat (talk) 17:40, 20 April 2016 (UTC)[reply]
From our PTFE article: "While PTFE is stable and nontoxic at lower temperatures, it begins to deteriorate after the temperature of cookware reaches about 260 °C (500 °F), and decomposes above 350 °C (662 °F).[39] The degradation by-products can be lethal to birds,[40] and can cause flu-like symptoms[41] in humans. See polymer fume fever." StuRat (talk) 18:46, 20 April 2016 (UTC)[reply]
Frying or boiling salmon? <shudder> IMHO there's only one respectful way to treat a nice piece of salmon, and that's to broil it, gently, so it's still translucent in the middle. However canned salmon can be nice in a scramble, with capers. --19:17, 20 April 2016 (UTC)
And then it goes on saying: "Meat is usually fried between 204 and 232 °C (399 and 450 °F), and most oils start to smoke before a temperature of 260 °C (500 °F) is reached,..."--TMCk (talk) 19:13, 20 April 2016 (UTC)[reply]
Right, and if the pan was fully submerged in oils with a low smoke point and kept below that smoke point, that would keep it at a safe temperature. But, the pan only has oil in the bottom, allowing the area above the oil to get hotter from heat that rises around the edge (especially on gas stoves on high) and higher temp oils may be used, and the pan may be left on the stove too long and smoke or even burn dry. (This can also happen when boiling in water, but I use a microwave oven to boil my salmon chili, which has a timer so I don't have to worry about that.) StuRat (talk) 00:41, 21 April 2016 (UTC)[reply]
The answer in general is: the more you sweat (like an athlete who trains regularly), the more salt you need in your diet, compared to someone who does not sweat a lot. However, I'm not sure that people in hot climates generally sweat a lot more than other people, people who live in hot climates are more acclimatized to the heat, wear less clothes, stay out of the sun, avoid strenuous activity during the hottest parts of the day, etc... Vespine (talk) 06:31, 20 April 2016 (UTC)[reply]
Hi Vespine. That doesn't quite answer the question. Let me be specific: Me. I live in Haikou. It's hot in the summer. I sweat a lot because it's broiling hot. I eat lots of salt year round. Is the salt I eat in the summer less harmful than the salt I eat in the winter. Anna Frodesiak (talk) 07:22, 20 April 2016 (UTC)[reply]
A tad disingenuous, maybe? For decades we've all been told of the health risks of too much salt. With all the conflicting health advice we get these days, it's not surprising if not everyone is up with the latest breathless revelations. And they may still not be up to speed by the time the next contradictory report comes along, restoring the status quo. Lesson: If you stay out of touch for long enough, you'll get back in touch again. Nothing new under the sun. -- Jack of Oz[pleasantries]09:53, 20 April 2016 (UTC)[reply]
Admittedly, it seems almost like a fringe opinion. Nonetheless, I think it deserves consideration! The central issue there is whether the health effects of salt represent causation or correlation. Personally, I am biased because of an incident that happened in my 20s. Over a few weeks I kept feeling more and more desire for salt, yet found it less and less satisfying ... eventually the salt even seemed to have a sour undertone, and I started thinking something was wrong with it. After some false ideas, I happened on a potassium salt substitute and it was just ... heavenly. Exactly the flavor I was looking for, extraordinarily satisfying, and that was the end of it. And so I wonder whether people who consume more salt are simply hungry for potassium but eating the wrong thing, and whether then it might make more sense to focus on potassium supplementation than cutting sodium. (A touch of epsom salt every now and then feels very nice to me also) Wnt (talk) 11:52, 20 April 2016 (UTC)[reply]
I don't believe your case is typical. I find potassium chloride to be repulsive (only acceptable in small amounts) , and absolutely hate it when something sold as "low sodium" has that added in it's place. I just want low sodium foods with nothing else added. Also, if you find regular table salt sour, that might be the added iodine. You can buy noniodized salt, but beware that you might not get enough iodine then. StuRat (talk) 17:28, 20 April 2016 (UTC)[reply]
@StuRat: Oddly enough, that was the first thing I tried during that period - but the fresh container of non-iodized salt seemed exactly as sour and unsatisfying. The sense of sourness went away almost entirely once I had balanced myself out a bit with potassium, though I am faintly aware of it to this day if I really think about it. The salt I use routinely is a "salt lite" (50% potassium 50% sodium); the two flavors complement each other well and it comes in bigger cheaper handier containers. The way I think of it, "salt" is a generic term for a mixture of ions, and sodium sits just a little to the sour side of the spectrum within it. Wnt (talk) 01:08, 21 April 2016 (UTC)[reply]
That's probably good, since most people get too much sodium and too little potassium. You might also try high potassium foods, like bananas. StuRat (talk) 01:14, 21 April 2016 (UTC)[reply]
Eventually, yes, but the problem is that the elevated sodium level can cause damage until it's corrected. Just a bit of damage each time, to be sure, but it's cumulative. StuRat (talk) 01:12, 21 April 2016 (UTC)[reply]
In general, people will adapt to heat, and after a few days or weeks, will excrete less salt with the sweat. So yes, you may need more salt intake in hotter climate, but the effect will be mostly temporary, and will be less than naively expected. --Stephan Schulz (talk) 13:11, 20 April 2016 (UTC)[reply]
That makes sense, and is what I would have guessed. But I don't know for sure, and I have no refs to back this idea up. Anyone else want to try to find refs along these lines? SemanticMantis (talk) 14:10, 20 April 2016 (UTC)[reply]
Ok this [19] is highly relevant (but paywalled), says "the data are best explained in terms of an active regulation of sweat composition" -- but that is with regard to exercise at different temps, not acclimatization effects. Here are some freely accessible papers: this one [20] is about sodium intake and sweat composition, and this [21] is about sodium secretion and re-absorption more basically. Note the last one is from 1965, and the first link (1982) may supercede some of the notions presented in the earlier paper. SemanticMantis (talk) 16:52, 20 April 2016 (UTC)[reply]
OR: I have sodium sensitive hypertension, as do my brothers (but oddly, neither of our parents). I've come to the conclusion that it's not so much sodium I consume, per see, but how much I consume relative to the amount of water I consume. So, if I drink more water (which I will need to, if sweating profusely), then I can consume more salt. StuRat (talk) 17:23, 20 April 2016 (UTC)[reply]
This entire thread seems like medical advice to me, which we don't provide here. I'm not bold enough to remove it myself, but perhaps someone else is. --69.159.61.172 (talk) 19:28, 20 April 2016 (UTC)[reply]
We have an unofficial guideline called Kainaw's criterion [22]. I don't see any response that says anything about treatment, medical diagnosis, or prognosis. What I see are references to WP articles and scholarly literature about the human body and biological processes. We should not give medical advice, but we are allowed to give biological information. If you do see a response that offers suggestions for treatment, diagnosis, or prognosis, please do remove them. SemanticMantis (talk) 20:09, 20 April 2016 (UTC)[reply]
This is certainly not medical advice to me. I don't give a hoot about salt. This follows an off-wiki discussion about how the body works. I said I'd post here and ask so I could say "Ha!" to someone.
In a nutshell, what I am asking is if salt does do some harm to arteries or kidneys etc. before it is peed out, is it disposed of better or earlier or less harmfully by sweating?. I mean, does it never see kidneys on the way. Do you see what I mean? And thank you all for the good information (so far). Anna Frodesiak (talk) 01:31, 21 April 2016 (UTC)[reply]
