I noticed the label says it's good for gargling, but doesn't list washing hands as a use. Is this because it would dry them out ? StuRat (talk) 01:30, 28 October 2015 (UTC)[reply]

H2O2 can oxidize surface skin cells and leave white spots on your skin. Doesn't usually happen with 3% if you wash it off promptly, but if you leave it on, it will. I certainly wouldn't gargle with undiluted 3% H2O2 — surely it says to dilute it first? --Trovatore (talk) 01:53, 28 October 2015 (UTC)[reply]

Actually, now I see that our article claims that the white spots are due to "a local capillary embolism", whatever that means. I'm a little skeptical; my impression is that the whitening is more superficial than that. I'd be interested to see a specific reference either way (the citation in the article points to a page that has four separate articles; doesn't say which article or page). --Trovatore (talk) 02:10, 28 October 2015 (UTC)[reply]

It's very strange that gargling is recommended. Our own article on hydrogen peroxide says, Large oral doses of hydrogen peroxide at a 3% concentration may cause irritation and blistering to the mouth, throat, and abdomen as well as abdominal pain, vomiting, and diarrhea. Intravenous injection of hydrogen peroxide has been linked to several deaths. Akld guy (talk) 02:02, 28 October 2015 (UTC)[reply]

Yes, vomiting, diarrhea, etc. are expected for an "oral dose", i.e. ingestion, but I think gargling is not a dose or ingestion. SemanticMantis (talk) 02:08, 28 October 2015 (UTC)[reply]

But if it can blister your mouth if you swallow it, I don't see why it wouldn't also blister your mouth if you rinse with it. Someone please check the bottle — I'm pretty sure the "gargling" usage is diluted, not full 3%. I don't think I'm likely to try it even diluted. --Trovatore (talk) 02:17, 28 October 2015 (UTC)[reply]

The bottle says to dilute with an equal quantity of water, so 1.5% concentration. StuRat (talk) 16:54, 28 October 2015 (UTC)[reply]

You made no mention of dilution in your original post. We have all been commenting on the basis that the concentration was 3%, which is what you did state. Akld guy (talk) 19:03, 28 October 2015 (UTC)[reply]

Well, my Q was about hand washing, which isn't mentioned at all on the label, so obviously there's no mention of concentration either. StuRat (talk) 01:58, 29 October 2015 (UTC)[reply]

Not only that, but if gargling were recommended with a strict admonition that it must always be spat out and not swallowed, it would only be a matter of time before someone would swallow a mouthful. Any instance where a product is intended to be placed in the mouth must cater for the fact that it will eventually be swallowed. The makers of chewing gum are mindful of that. Akld guy (talk) 05:33, 28 October 2015 (UTC)[reply]

A few drops, yes, but if somebody drinks a gallon of a gargle, they can't blame the manufacturer. A few drops should be nicely diluted and not pose any problem in the stomach. StuRat (talk) 06:05, 28 October 2015 (UTC)[reply]

Lots of websites seem to recommend diluting OTC H2O2 3% down to 1.5% or 1% for gargling and other oral care, but that other products equivalent to 3% or stronger is not uncommon for tooth whitening. A capillary embolism is fun, if your idea of fun is an embolism in your capillaries (tiny bubbles of oxygen under your skin). DMacks (talk) 02:19, 28 October 2015 (UTC)[reply]

Is that for real though? The spots seem very superficial, not deep enough that a cut that deep would bleed. Maybe they're sort of disused capillaries, passages where red cells used to travel back when that part of your skin was alive? --Trovatore (talk) 02:24, 28 October 2015 (UTC)[reply]

I am similarly skeptical. The epidermis doesn't have blood vessels (as our article says). The living parts obtain nutrients through diffusion, as do other avascular tissues like the cornea. --71.119.131.184 (talk) 04:59, 28 October 2015 (UTC)[reply]

Plenty of sources say the same, although some call it micro-embolisms Ssscienccce (talk) 10:08, 28 October 2015 (UTC)[reply]

Australian Dental Association study reports[1] long-term oral use of ≤3% was generally safe. DMacks (talk) 02:31, 28 October 2015 (UTC)[reply]

Say you had a large parabolic reflector aimed at a lens designed to focus the light into a beam. How much light could you send through the lens before the lens itself started overheating? Cpergielx (talk) 02:21, 28 October 2015 (UTC)[reply]

Let see. Some factors would be:

1) How close to perfectly transparent the lens is. If it really was 100% transparent, then an infinite amount of light could pass through (unless we count photons occasionally spontaneously decaying).

2) How small the lens is. A smaller (and in particular thinner) lens should be able to cool off more quickly.

3) What surrounds the lens. Some materials will carry heat away faster than others.

4) How hot the lens can get before it fails. If glass, melting is one possible failure mode, but uneven heating might also make it crack. A material with a zero coefficient of thermal expansion would resist cracking best, as long as the material to which the lens was mounted also didn't expand or contract.

5) The duration of the light beam. For use in lasers, it can be extremely short, and very little heating will occur in that time.

6) Note that some form of active cooling system, like oil circulated through the center of the lens, might keep it much cooler (although then you would also need to worry about the boiling point of that fluid). StuRat (talk) 04:57, 28 October 2015 (UTC)[reply]

Re 1) At 150,000 to 300,000 photons to the electron mass and Avogadro's number of atomic masses to the gram, the mass-energy of finitely bright light in the 100% transparent lens would exceed the supertanker in a pinhead density of a neutron star and therefore the maximum possible luminosity and the entire light-path will collapse into a black hole. Presumably, far before that you could put supertankers in orbit around the light beam if this was in deep space? Sagittarian Milky Way (talk) 05:26, 28 October 2015 (UTC)[reply]

Transparency of glass to sunlight is the key question. I'm not finding much. Cpergielx (talk) 11:53, 28 October 2015 (UTC)[reply]

The technical term is "Laser Damage Threshold" - see, for example, this datasheet for details on how it's calculated and results for various lenses. Tevildo (talk) 13:22, 28 October 2015 (UTC)[reply]

It depends on what you mean by "glass". I recall someone telling me that the glass used in optical fibers is so transparent that a kilometer of the stuff has the same transparency as a single sheet of window glass. So there is a massive variation possible between the best and the worst and "glass" becomes an impossibly vague term. SteveBaker (talk) 15:33, 28 October 2015 (UTC)[reply]

I'm someone who spends time putting LOTS of light through small lenses every day, (my wife's business involves laser cutting - and I maintain our two Lasersaurs) - our CO2 lasers put out 120 watts of infra-red light in a ~10mm diameter beam and a 25mm diameter gold-coated zinc/selenium lens focuses the beam to an 0.03mm spot. As you might guess from the exotic nature of the materials - getting that much IR light focussed though that much lens is difficult.

As a practical matter, there are three issues:

1. What percentage of the incoming light is reflected away, back towards the source? This is wasted energy (because it didn't end up where you wanted it) - but that reflected energy has to go someplace - and there is a lot of incoming energy, that might be problematic (it certainly is in my case). A lens may scatter the light back out through a wider angle, effectively diluting it to the point where it may not matter - but when the amount of incoming energy is really high - that may not be enough to prevent problems.
2. What percentage of the incoming light is absorbed by the lens? This is also wasted energy - but where the energy goes is almost certainly in heating up the lens. If the lenses I used were (say) 99% transparent - then the lens would heat up and shatter in a matter of seconds because 1% of the incoming energy is still a lot of energy! So I need something like 99.9% to allow the heat to radiate off of the lens as fast as it accumulates. Overheating the lens can cause a variety of problems - the lens might overheat and shatter or melt - the thing holding the lens in place might suffer - any fancy coatings on the lens might boil away or corrode in some fashion - it's certainly not a good thing!
3. What contaminants or other damage is likely to occur on the lens? Any kind of scratch or scuff will wreck the transparency of the lens...(see (2), above) and any kind of contaminant (dust, water condensation, etc) will also absorb the incoming light, get hot, etc, etc. So keeping the lens clean and avoiding it being touched by anything that might scratch it becomes a big deal. Ordinarily, when you care about something being contaminated by the environment, you encase it with something. But in this case, the "something" has to transmit light at least as efficiently as the lens - and then it has to be protected too - so you just get into an infinite regress.

There are certainly theoretical limits to what you can manage - but the practical issues are much more of a problem. Our lenses last only a couple of months before they have to be replaced. SteveBaker (talk) 15:29, 28 October 2015 (UTC)[reply]

What is the typical failure mode for your lenses ? As for keeping dust off them, there's a clean room or an evacuated chamber for the entire apparatus, but, in addition to being prohibitively expensive, if you are using the laser to cut, that will generate lots of gas and/or dust. StuRat (talk) 16:52, 28 October 2015 (UTC)[reply]

Laser cutting wood (which is what we do most of) produces a lot of smoke - which we pull away from the lens with some seriously powerful fans. There is also a small air compressor that blows clean air both over and under the lens in an effort to divert more smoke away from it. However, despite all of those efforts, it does slowly get contaminated - which soon becomes be fatal for the lens because the dirt collects laser energy, heats up and wrecks it. So we have to clean the lens every dozen or so operating hours - but because the surface of the lens is coated with a layer of gold that's just a few atoms thick - and the zinc/selenium stuff is about as hard as candle way - it's terrifyingly easy to scratch or scuff the surface. It winds up being a trade-off between the benefits of cleaning it versus the hazards of cleaning it! So no matter how careful we are, we end up replacing the lens every once in a while. We used to pay $300 for them - but with the popularity of these small laser cutters growing, we now find we can get them for around $60...which is some small fraction of a dollar per hour for a machine that can easily earn $1 to $2 per minute while it's running. SteveBaker (talk) 20:27, 28 October 2015 (UTC)[reply]

Wouldn't enclosing the lens in a glass box solve the problem ? The smoke would accumulate on that, which you could clean without fear. StuRat (talk) 01:52, 29 October 2015 (UTC)[reply]

You've entirely missed the problem though - how does the light get through the glass box (and out of it again)? Glass is much less transparent (and more reflective) to light at this frequency than my lens is - so the glass box would heat up and pretty soon shatter. Also contamination would wind up on the surface of the glass - with much the same result. The point is that the lens is already made of the best material for the job - so all you could do would be to surround it with more of that same material - so you'd be no better off! The best we can do (and what we actually do on the more vulnerable underside of the lens) is to enclose it in an opaque box with holes just large enough to permit entry and exit of the light beam. Then we pump filtered air into the box to create enough positive pressure inside to keep the smoke out. Sadly, that's not 100% effective - there is inevitable turbulence in the air leaving the box, and those swirls are enough to pull small amounts of smoke and other contaminants into the box and onto the lens. There is no easy way out of this - which is why high transparency and low reflectivity of the lens material and the avoidance of contamination impose practical limits on the amount of light you can push through a lens. SteveBaker (talk) 15:41, 29 October 2015 (UTC)[reply]

Well, the glass box could be a compromise, less expensive than the lens, if for no other reason than being flat. And, if you could skip that fragile coating, then you could clean it without ruining it. If the glass box occasionally fractures, just replace it, it should be cheap. You could also put all your air handling schemes into effect around the glass box, too. StuRat (talk) 00:45, 1 November 2015 (UTC)[reply]

@SteveBaker: Hmmm... There's no chance you could enclose the chamber where the smoke is generated, and have the beam come into it from directly beneath after reflecting off a pair of flat mirrors set at 45-degree angles underwater? The water would block smoke from getting back at the laser... supplying it with a small, constant flow from a tap would keep the system clean and cool... by having the beam perpendicular to the surface you'd reduce, though not eliminate, the havoc wrought if something knocks the apparatus and kicks up waves in the tank. Wnt (talk) 18:19, 31 October 2015 (UTC)[reply]

A "lens" may be more than a convex piece of glass, where the failure mode would be cracking due to uneven heating, or in the extreme literal melting. A multi-element lens may have multiple types of glass in it (if I recall correctly, crown and flint glass) to correct for certain aberrations. It may have groups of such elements to achieve the best image quality, if used as a telescope, binocular or camera lens. Lenses which are ideal for use in a view camera, for instance, may overheat and fail when used in a projector or photo enlarger. A similar focal length of lens made for use in a video projector, slide projector or movie projector would not have cement which would fail when light from a high power lamp passes through it.A camera lens might also have an iris or Waterhouse stop in it to reduce the light transmission and increase the depth of field, and it could overheat and warp r catch fire if made of a flammable substance. The shutter itself could similarly fail form overheating before the actual glass/plastic lens elements failed. A projector system I'm familiar with used a "cold mirror" in front of the lamp which selectively diverted visible wavelengths of light from the longer infrared wavelengths, which contributed to overheating of the film and optical path without contributing to image brightness. Edison (talk) 17:19, 28 October 2015 (UTC)[reply]

• The National Ignition Facility (a giant US government experiment to create nuclear fusion by blasting pulsed lasers at very small targets) puts over 3 GW/cm² through its lenses (which are made of fused silica) – that would be equivalent to putting the entire power output of Hoover Dam through your little fingernail. Luckily, they only operate for a very brief period of time, so the total energy input into the lens is small: this article says 9 joules of ultraviolet per square centimetre, which wouldn't even give you a suntan if you absorbed it in a second... but absorbing it all in a single nanosecond can have explosive results. Smurrayinchester 14:16, 30 October 2015 (UTC)[reply]

Does everyday masturbation increases DHT production thereby increasing hairloss ? — Preceding unsigned comment added by 175.101.24.136 (talk) 09:11, 28 October 2015 (UTC)[reply]

Probably not on your palm. ←Baseball Bugs ^{What's up, Doc?} carrots→ 15:32, 28 October 2015 (UTC)[reply]

The general consensus is that there is no such effect. Most studies that have looked at the effect of masturbation on testosterone levels in men have found it to be small and inconsistent. Looie496 (talk) 20:32, 28 October 2015 (UTC)[reply]

"Everyday" meaning daily, or "everyday" meaning non-exotic? Enquiring minds would like to know. {The poster formerly known as 87.81.230.195} 185.74.232.130 (talk) 14:23, 29 October 2015 (UTC)[reply]

What is the element with least amount of weight that follow all those rules?
1-Its not ultra rare
2-Can be used safely, its not radioactive, not burn easily......
3-Is found on solid state on normal temperature.
201.79.56.139 (talk) 16:36, 28 October 2015 (UTC)[reply]

Carbon ? Note that "burns easily" and "can be used safely" are somewhat at odds. Carbon has both radioactive and nonradioactive isotopes, as do most elements (there are three naturally occurring isotopes, with ¹²C and ¹³C being stable, while ¹⁴C is radioactive, decaying with a half-life of about 5730 years). "Light weight" is somewhat subjective, as different molecules will have different weights. Diamonds are a fairly heavy form of carbon, while carbon nanotubes and buckyballs are fairly light. StuRat (talk) 16:39, 28 October 2015 (UTC)[reply]

I read item #2 as "not burn easily", in keeping with the "can be used safely" theme. While carbon can be ignited and then it burns easily (at least in some forms), it's pretty easy to simply not ignite it (unlike pyrophoric materials). DMacks (talk) 16:50, 28 October 2015 (UTC)[reply]

Yes, we need a clarification from the OP on whether it should burn easily or NOT burn easily. As for how simple it is to avoid igniting it, that rather depends on the use they had in mind. If it's going to be used for the walls of a kiln, that's not so easy (although still possible, say by coating it with something fireproof). StuRat (talk) 16:57, 28 October 2015 (UTC)[reply]

Also, he needs to clarify "least amount of weight". Are we talking density or are we talking molar mass? By molar mass, the lightest "shelf stable", non-radioactive, non-flammable, common solid element is probably aluminum. It is the Third most abundant element on earth, while it is nominally very chemically reactive, any sample of aluminum exposed to air produces an impenetrable coating of protective aluminum oxide, which is why aluminum is stable enough for use in cans, food wrapping, cooking dishes, etc. It doesn't burn, it isn't overly radioactive, etc. In terms of density, however, the element that matches the OP's requirements is likely [silicon]. Every element less dense than silicon is either a gas, or highly chemically reactive, or flammable. Silicon is fairly inert stuff. The reason why silicon is less dense, even though its atoms weigh more than aluminum is because the crystal structure of silicon means that its atoms are more spread out, making the bulk material "lighter" than aluminum. I hope that helps the OP get what they are looking for. --Jayron32 17:05, 28 October 2015 (UTC)[reply]

Aluminium does burn, aggressively and hotly. Powdered aluminium is used in pyrotechnics. Solid aluminium is hard to ignite, but once it burns, it burns. --Stephan Schulz (talk) 19:42, 28 October 2015 (UTC)[reply]

Almost every element burns. Iron burns. Aluminum, in any form the OP is going to work with it, is not dangerously inflammable. You can safely use aluminum cookware on your stovetop, and stand no chance of it bursting into flame. --Jayron32 20:10, 28 October 2015 (UTC)[reply]

If the OP's "burn easily" is meant literally, calcium is probably the best candidate (1.55 g/cm³, lighter than graphite at 2.27) - lithium and beryllium are lighter, but probably fail the "used safely" test. Tevildo (talk) 17:12, 28 October 2015 (UTC)[reply]

And yet, graphite is used to line kilns and crucibles, as lubricants even at very high temperatures, and as electrodes in furnaces. DMacks (talk) 17:15, 28 October 2015 (UTC)[reply]

Please do your own homework.

Welcome to the Wikipedia Reference Desk. Your question appears to be a homework question. I apologize if this is a misinterpretation, but it is our aim here not to do people's homework for them, but to merely aid them in doing it themselves. Letting someone else do your homework does not help you learn nearly as much as doing it yourself. Please attempt to solve the problem or answer the question yourself first. If you need help with a specific part of your homework, feel free to tell us where you are stuck and ask for help. If you need help grasping the concept of a problem, by all means let us know.--Aspro (talk) 19:29, 28 October 2015 (UTC)[reply]

In what sort of school is "not ultra rare" considered an appropriate way of specifying a homework question in science? (Never mind, don't answer that.) --70.49.170.168 (talk) 04:51, 29 October 2015 (UTC)[reply]

I'm not sure why people haven't considered boron here. Yeah, it's expensive - $5 a gram, or about 1/8 the cost of gold (though also 9x less dense) - in its crystalline state. But you can buy a bottle for a couple of bucks in oxidized form as a roach killer, so the cost is basically purification, and of course if you purify anything enough it costs ... question said rare, not cost. Rare in the cosmos, not so much in certain dried-up lakes. Wnt (talk) 21:42, 28 October 2015 (UTC)[reply]

It's too heavy - 2.34 g/cm³, as against silicon at 2.33. Tevildo (talk) 21:57, 28 October 2015 (UTC)[reply]

Some clarifications, nope its not a homework, burn easily is a typo the real thing is not burn easily, with weight I mean the density201.79.56.139 (talk) 15:24, 29 October 2015 (UTC)[reply]

In that case, the best answer is probably carbon, in the form of graphite - density about 2.2 g/cm³ (lighter than silicon), and "difficult to ignite" (according to our article). Tevildo (talk) 22:52, 29 October 2015 (UTC)[reply]

Hi all, with the recent developments in space (the blood moon and other eclipses, water on Mars, the photographs of Pluto's surfaces, etc.) I would like to be able to share them with a group of kids (~6 to 8 years old). I'm not confident enough to adapt a source that's aimed at adults on the fly, and the NASA Kids Club doesn't seem to be a news service. Could you please help me find a reputable news service for kids which covers outer space topics? If not a service, just some recent kid-focused articles with pictures that I can use to help explain what's new in outer space. Thank you. --211.30.17.74 (talk) 21:43, 28 October 2015 (UTC)[reply]

A good space-related news site for kids may be http://www.timeforkids.com/minisite/space, though some of the articles are quite technical, and better suited for older children. http://www.planetsforkids.org/news/ seems nice but outdated, and http://www.funkidslive.com/?s=nasa&x=0&y=0 may also be interesting. - Lindert (talk) 22:52, 28 October 2015 (UTC)[reply]

The European Space Agency runs a space news website, ESA Space for Kids, but it also looks a bit outdated, the newest item is from September. --Jayron32 23:32, 28 October 2015 (UTC)[reply]

Found a kids news website called "Kids Ahead" which has a space news section: [2] It seems to be more of a news-and-press-release aggregator however, and doesn't seem to have its own content geared towards children. --Jayron32 23:36, 28 October 2015 (UTC)[reply]

How do both compare in terms of efficiency? Is what is happening inside the phone charger the same physical phenomenon (inductive power transmission) as in the case of the wireless charger? Could wireless charging be made almost like conventional charging (using a cable)?--Scicurious (talk) 00:08, 29 October 2015 (UTC)[reply]

See Battery charger which is Wikipedia's overview article. There are many different designs of chargers. You can read about them at your leisure. --Jayron32 01:00, 29 October 2015 (UTC)[reply]

There is a short description there about how an inductive charger works, but little as to how much energy is lost to heat when you don't have a direct connection. --Scicurious (talk) 15:50, 29 October 2015 (UTC)[reply]

As an anecdote (this is not data)... I have both a hard-wired mini-usb charger and an induction wireless charger. My phone goes from around 30% (which is what it has when I get to work in the morning on average) to 100% in about 20 minutes. Neither one works faster. The time is just about the same. I stopped using the wireless charger. It isn't because it is slower. It is just as fast and much more convenient. I stopped using it because it is impossible to turn off the very loud "HEY EVERYBODY!!! I'M CHARGING!!!" tone in Android without completely muting the phone. So, once my phone is charged on the wireless charger, it stops charging. A few seconds later, it realizes it is still on the charger and screams out the "I'M CHARGING!" noise. Then, it realizes it is fully charged and stops charging. Then, it realizes it is still on the charger and screams out the "I'M CHARGING!" noise again - over and over and over. It is OK if I'm at my desk. But, if I'm not, it goes off over and over and over, annoying everyone within earshot. So, I stick with the USB charger which doesn't have that design fault.

I wonder if that's a phone model issue: My phone (Galaxy 5s with a special backing plate) only makes the obnoxious noise on the initial placement of the phone, not after the charge fills. Mingmingla (talk) 01:20, 30 October 2015 (UTC)[reply]

The same charging time doesn't mean the same efficiency, though. Phone batteries can only take a few watts worth of charging current, while a home outlet can supply more than a kilowatt, so it would take ridiculous inefficiency to affect the charging time. -- BenRG (talk) 04:10, 30 October 2015 (UTC)[reply]

According to this presentation, the efficiency is similar. The author is biased toward wireless charging, but the presentation includes a lot of technical information and seems plausible enough. -- BenRG (talk) 04:10, 30 October 2015 (UTC)[reply]

209.149.114.132 (talk) 17:17, 29 October 2015 (UTC) @Scicurious:problem:insufficient research dataMahfuzur rahman shourov (talk) 17:20, 29 October 2015 (UTC)[reply]

3kW systems >95%; 5W: 75%-80% efficiency. That is the inductive transfer efficiency, in other words: only the wireless part. So yes, they are less efficient. Source from battery university removed... Blacklisted site. Ssscienccce (talk) 21:43, 30 October 2015 (UTC)[reply]

Well, the point made both by the OP and by the presentation I linked is that wired power supplies use inductive coupling in the transformer, so they also pay the "only the wireless part" penalty. Wireless charging just puts the two halves of the transformer in different boxes. It's not obvious that that will be equally efficient, but it's not obvious that it won't be. -- BenRG (talk) 02:17, 31 October 2015 (UTC)[reply]

Why would the Manhattan Project's Metallurgical Laboratory need a radiobiologist? To track the effects of radiation on the other workers? Obviously she performed useful postwar research on radiobiology, but most of her work seems completely irrelevant to the process of creating a nuclear weapon. Nyttend (talk) 12:01, 29 October 2015 (UTC)[reply]

If you're asking about Miriam Posner Finkel, this says she "worked on establishing the basic toxicity levels of radionuclides". -- Finlay McWalterᚠTalk 12:15, 29 October 2015 (UTC)[reply]

Yeah, I didn't click your link -- Finlay McWalterᚠTalk 12:24, 29 October 2015 (UTC) [reply]

Their day in the sun: Women of the Manhattan Project (Howes & Hezenberg, p 118) says the biology division was tasked to examine "the metabolism of radioactive materials" and their health effects. MPF et al. did animal studies on the health effects of radionuclides, including plutonium and strontium, other transuranics, and fission products. Given that most of these radioisotopes were novel, and their new (comparative) abundance unprecedented, it's easy to see why this knowledge would be valuable both for the research and production process (and the consequence of its effluent) and the short and long term effects of the weapon. -- Finlay McWalterᚠTalk 12:35, 29 October 2015 (UTC)[reply]

Your question seems to be a teleological one: "Why did those in charge of the Manhattan Project decide to hire a radiobiologist?" There were a lot of employees involved in the Manhattan Project, including the many employees at sites like Hanford and Oak Ridge. Given this, it's not surprising the Project was interested in the biological effects of radionuclides. If your workers are getting sick or dropping dead, that's a problem. The Manhattan Project was inventing entire fields of nuclear physics and engineering from scratch; many of the things it was doing had never been done before. This was uncharted territory. --71.119.131.184 (talk) 22:31, 29 October 2015 (UTC)[reply]

Hey, do you have any good refs for Oak Ridge and the Manhattan Project? I've briefly looked in the past and came up lacking. I'd like to see a nice well-referenced historical account of what went on there ~1935-2000 :) SemanticMantis (talk) 01:40, 30 October 2015 (UTC)[reply]

Off the top of my head, no. --71.119.131.184 (talk) 06:07, 30 October 2015 (UTC)[reply]

If anything, they didn't do enough research into the dangers of radioactivity to respect the dangers it posed, for at least another decade. Nuclear tests in the Southwest US may have increased the risk of cancer to many in the area, including John Wayne, who shot a film in the fallout area. See John Wayne#Death. StuRat (talk) 05:34, 30 October 2015 (UTC)[reply]

I don't actually know, but it also seems worth considering that the bomb was meant to kill people, and so a radiobiologist might also come in handy for trying to figure out how to enhance, direct and control the fallout kill. Wnt (talk) 11:59, 1 November 2015 (UTC)[reply]

[Somehow I made my way to the Szilárd petition while investigating for this question. Don't know how many rabbit trails I followed...]

Last year, I added this picture to the Fermanagh Township, Juniata County, Pennsylvania article. I've just revised the caption, but I thought I'd better check: is my new caption an accurate description of the scene? Nyttend (talk) 12:13, 29 October 2015 (UTC)[reply]

Looks good to me. --Jayron32 12:23, 29 October 2015 (UTC)[reply]

I would add in the age of the rocks involved - in this case Silurian (from a map that I downloaded from here - you want the East sheet, but it is in a big (>80Mb) zipped file). I would also reword it - "with visible anticline in Silurian rock strata". Mikenorton (talk) 12:57, 29 October 2015 (UTC)[reply]

...and add that useful reference to back up the text. Bazza (talk) 14:12, 29 October 2015 (UTC)[reply]

OP curiousMahfuzur rahman shourov (talk) 16:41, 29 October 2015 (UTC)[reply]

Impossible to calculate from the information given. For starters, it will depends significantly on battery type, since the typical charging profile varies from battery to battery. The actual charging profile will depend on the device using to charge the battery, which will probably also affect the definition of maximum charge. On a related note, the output of the maximum rate output of the power cord (which is likely to be what is printed on it so I assume is what you mean by "powerchord of given A/mA") doesn't tell you what current is used to charge the battery. Nil Einne (talk) 17:43, 29 October 2015 (UTC)[reply]

@Nil Einne:battery take power same ampere as cord, how long take for given Ah or mAh or MAhMahfuzur rahman shourov (talk) 17:47, 29 October 2015 (UTC)[reply]

Mahfuzur, It will be easier to discuss things here if you follow WP:INDENT, see also WP:THREAD, thanks :) SemanticMantis (talk) 17:50, 29 October 2015 (UTC)[reply]

What battery are you using that can know what the maximum of the power cord happens to be and that uses a constant current charging profile until full? In any case, it's a fairly simply division, the units should make it obvious. (If you make sure you cancel out the outs, this should hopefully also avoid mistakes if one is in A and on is in mA so it's a useful test anyway.) Nil Einne (talk) 18:41, 29 October 2015 (UTC)[reply]

First identify the battery type in List of battery types as a Rechargeable battery because the particular battery technology will define what charging process it tolerates. See Rechargeable battery#Charging and discharging. There can be a wide range of charging regimes; these range from A) a simple slow charger that typically takes 14 hours or more to reach a full charge, which finishes in a small trickle charge current that just compensates a cell's self-discharge rate, to B) fast chargers that detect when a cell reaches full charge (change in terminal voltage, temperature, etc.) to stop charging before harmful overcharging or overheating occurs. Common examples for a Lead–acid battery are 1) charge by a constant-voltage 2.23V (13.4) by type A charger (the value is brackets is the Float voltage for a 6-cell automobile battery), or 2) the more complex type B IUoU battery charging regime. For a lead-acid battery rated at 40 Ah the maximum current during the initial phase can be 4 A; this will bring the battery to around 95% of its capacity and may take anywhere between 2 to 8 hours depending on the initial state of discharge. Other battery technologies have stricter charging requirements, and can be damaged by overcharge, so it is essential to follow the manufacturer's recommendations. Lithium-ion batteries now used in electric tools and some electric cars can be dangerous under some conditions and pose a safety hazard since they contain, unlike other rechargeable batteries, a flammable electrolyte and are kept pressurized. Bestfaith (talk) 18:44, 29 October 2015 (UTC)[reply]

That's what I said in my first post, but then the OP insisted that their hypothetical (I'm pretty sure it's hypothetical since the OP only asked for an equation & said nothing to indicate they were actually charging a battery) battery uses a constant current charging profile, that just so happens to be magically the same as the maximum of the power cord. If the OP wants to calculate the charging time for this magical battery, I guess that's up to them, but given how simple it is, they probably should try and do it themselves. 18:51, 29 October 2015 (UTC)

Does science have any axioms that are not actually mathematics or philosophy? --Scicurious (talk) 22:55, 29 October 2015 (UTC)[reply]

The concept of an axiom (something that is assumed to be true without any proof) is somewhat counter to the purposes of science, which is (roughly) to investigate the world and determine how it really works. There are certainly statements that are generally regarded as true and are taken to be the base of a large body of subsequent work (for example, that the speed of light is a constant), but for the most part scientists only make use of them because they're backed up by experimental evidence. Statements about how the world work do not 'commends themselves as evident', at least in an absolute sense. That said, part of the scientific process is making hypotheses about how the world might work, and working out the logical conclusions from there. For example, a group of scientists might say "What if subatomic particles were made of little vibrating strings, instead of being dimensionless points?" and work out how the world would look if that statement were true. But that's not really an axiom of "science", construed broadly. It's just an axiom for that particular hypothesis/theory. If the scientists working with that assumption can't back it up with evidence, then they are (frequently) criticized for it. - If there was anything that came close to an "axiom" in science, in the same sense it was used in mathematics,it wouldn't be with any sort of scientific facts about the world. Instead, the "axioms" of science would probably revolve around the scientific method itself. For example, the assumptions that events are repeatable (e.g. if you set up the experiment the same way twice, you'll get equivalent results), that reality is objective (e.g. two people doing the same thing can get the same results), that the rules of logic apply to reality (e.g. if you reach a contradiction, one of your assumptions is flawed ), etc. But even then, most of these are backed up by experience (evidence), so might not quite be counted as "axioms", depending on how broadly you define what an "axiom" is. -- 160.129.138.186 (talk) 23:33, 29 October 2015 (UTC)[reply]

All good stuff, I'll add the links to the concepts of repeatability and falsifiability. Philosophy of science, Epistemology, and Scientific law are relevant broad articles. WP:OR Most contemporary practicing scientists I know are implicitly Popperian, and if we construe "axiom" broadly enough, then everything is an axiom. If we construe "broadly enough" broadly enough, then everything is a piece of broccoli :) SemanticMantis (talk) 00:20, 30 October 2015 (UTC)[reply]

The other article to read is solipsism, which is where you get when you think about these things broadly enough. Solipsism is the Reductio ad absurdum that we get when we try to require that all knowledge must extend from observation only, and that we can never take any belief on faith. Solipsism is the philosophy without axioms. --Jayron32 01:21, 30 October 2015 (UTC)[reply]

I would suggest that methodological naturalism is generally assumed in science (and for good reason). --Stephan Schulz (talk) 01:34, 30 October 2015 (UTC)[reply]

• The closest you'll get to axioms are probably principles which state our underlying assumptions about the universe. These are (mostly) probably testable, but only indirectly and with great difficulty. For example, the Copernican principle ("Our position in the universe is not special, but instead entirely average") is a simple assumption which is used to allow us to apply physical laws in places we can never really visit (although there are ways of testing its limits, which is easier now than it was in Copernicus' day). Perhaps the laws of nuclear physics are totally different in the Andromeda Galaxy, who knows? But we assume that they work the same way even though there's a pretty good chance humanity will never be able to test that one way or the other (that's partly Occam's Razor, which I guess is a philosophical axiom). Smurrayinchester 09:25, 30 October 2015 (UTC)[reply]

• To me, the most obvious "axiom" in science is that we can trust our observations, within the limits of whatever tools we observe with. ←Baseball Bugs ^{What's up, Doc?} carrots→ 13:34, 30 October 2015 (UTC)[reply]

Yes, that's certainly true. Then we have "cogito ergo sum" and all that it implies. Also the idea that the universe actually has rules and isn't completely arbitrary is an important underlying assumption. Some of those basic ideas turned out to be incorrect "God does not play dice" was an axiom that Einstein stuck with (to his great cost, some would say), even though evidence to the contrary was piling up in ugly, unruly piles from the quantum theorists and the experimental evidence backing them up. SteveBaker (talk) 14:07, 30 October 2015 (UTC)[reply]

I would concur with Einstein that God does not "play dice" with the universe. Einstein's failing was in not understanding the nature of what looks like "randomness" to us mere mortals. That is, the subtle forces that have "mis-shapen" the universe. If there were no randomness, everything would look the same. ←Baseball Bugs ^{What's up, Doc?} carrots→ 14:55, 30 October 2015 (UTC)[reply]

Einstein's Special_relativity#Postulates is a sort of example of axiomatic thinking - although he called them "Postulates". Einstein started out his work on Special relativity by assuming:

• The Principle of Relativity – The laws by which the states of physical systems undergo change are not affected, whether these changes of state be referred to the one or the other of two systems in uniform translatory motion relative to each other.
• The Principle of Invariant Light Speed – "... light is always propagated in empty space with a definite velocity [speed] c which is independent of the state of motion of the emitting body". That is, light in vacuum propagates with the speed c (a fixed constant, independent of direction) in at least one system of inertial coordinates (the "stationary system"), regardless of the state of motion of the light source.

He didn't have solid proof of the first postulate - but like most axioms, it just seems "reasonable" - but there was actual evidence of the second one. However, just as a mathematician moves from a small set of axioms to produce theorems that depend on those axioms to be true - so Einstein moved from those two postulates to come up with special relativity - which he was able to demonstrate to be true, providing the two postulates are true. SteveBaker (talk) 14:07, 30 October 2015 (UTC)[reply]

• There is basically one axiom and one axiom-like rule. The "axiom" essentially says that the scientific method yields correct results, or to put it differently, that inductive logic is valid. As David Hume argued very convincingly, this principle must be taken on faith, because any attempt to prove it is inevitably circular. The "axiom-like rule" is Occam's razor, which states that when we confront a situation that has multiple possible explanations, we should choose the simplest one that accounts for the observed facts. Looie496 (talk) 15:15, 30 October 2015 (UTC)[reply]
  • Right, like the argument that bumblebees can't fly. When it comes to yielding "correct" results, the caveat is that they are only as "correct" as the assumptions on which they're based. And Occam's razor is not foolproof, since religious fundamentalists will say there is no simpler explanation than "God does it all." ←Baseball Bugs ^{What's up, Doc?} carrots→ 19:06, 30 October 2015 (UTC)[reply]

Baseball Bugs doesn't seem to understand Occam's razor. It isn't "the simplest" explanation that wins. Our article says "Among competing hypotheses, the one with the fewest assumptions should be selected."...and assuming the existence of a supernatural being with omniscience, omnipresence and omnipotence without a single shred of experimental evidence creates an enormous pile of assumptions - which is why "God did it" isn't a popular explanation amongst scientists. SteveBaker (talk) 21:30, 30 October 2015 (UTC)[reply]

This doesn't have to do with axioms, but with the claim that science claims that bumblebees cannot fly. That is a misunderstanding. I have read two explanations of that misstatement. The first is that the laws of aerodynamics as normally formulate cannot explain the flight of the bumblebee because the laws of aerodynamics do not scale down well to aircraft of bumblebee size, for which microscopic and possibly quantum effects figure. The second is that the laws of aerodynamics say that a bumblebee cannot fly with rigid wings, which in turn means that bumblebees have flexible wings. I don't know which or both is true, but the claim that science says that bumblebees cannot fly is itself a myth. Robert McClenon (talk) 19:17, 30 October 2015 (UTC)[reply]

It has to do with claiming that science yields "correct results". Results are only as correct as the assumptions on which those results are based. And as you've indicated, one scientist, a century or so ago, claimed that bumblebees shouldn't be able to fly. Obviously, they can, so that scientist's assumptions were wrong, and hence did not yield correct results. ←Baseball Bugs ^{What's up, Doc?} carrots→ 19:30, 30 October 2015 (UTC)[reply]

"Science" has never denied that bumblebees can fly. Science has reality checks. Scientists know that if a scientist proves something that is contrary to observations, then there is something wrong, maybe with the proof itself, or maybe with the assumptions. I think we are saying the same thing. Robert McClenon (talk) 19:44, 30 October 2015 (UTC)[reply]

Hey, it's almost like we have a wealth of information at our fingertips here - Bumblebee#Misconception_about_flight. Nobody ever seriously claimed bumblebees can't fly. It's just gotten terribly twisted around. One guy one time said that he heard about someone doing a "back of the envelope" calculation and getting an incorrect result. Far off topic, but let's put the bees to rest. SemanticMantis (talk) 19:48, 30 October 2015 (UTC)[reply]

For a comprehensive explanation of the bumblebee nonsense check out Snopes' article on the subject. Bottom line - utter bullshit. Some airplane aerodynamics "expert" did a back-of-envelope the wing loading calculation and said that he couldn't understand how a bee could fly - but he was basing it on equations for a fixed wing airplane. A bee's wing loading is considerably less than a typical helicopter - which is a more realistic mechanical analogy anyway. SteveBaker (talk) 21:30, 30 October 2015 (UTC)[reply]

What needs to be put to rest is the claim that "the scientific method yields correct results." That amounts to religious dogma, and can't stand close examination. ←Baseball Bugs ^{What's up, Doc?} carrots→ 20:03, 30 October 2015 (UTC)[reply]

The scientific method does yield correct results - but not always in the very short term. But considered over decades, the scientific method has a better track record than any other approach to explaining "the way things work". It would be naive to assume that no mistakes are ever made over the short term. SteveBaker (talk) 21:30, 30 October 2015 (UTC)[reply]

I think that science is chock full of "axioms", in the sense that we take a million things for granted that we just haven't scrutinized in our minds. When you (mythically) drop iron balls off the tower of Piza, you assume that the rate of fall has something to do (or not) with the weight of the ball or friction with air passing it, rather than some kind of soliton matrix embedded in the air or miniature jinn policemen enforcing speed limits. The whole world is axiom, assumptions we make in ignorance; the scientist is a little Dwarf Fortress digger somewhere in the middle trying to expand his colony one swing of the pick-axe at a time. Wnt (talk) 15:33, 30 October 2015 (UTC)[reply]

Of course "axiom" doesn't have a single terribly clear definition that will serve in all contexts. And of course we scientists make assumptions all the time. But those are better called assumptions or postulates or fiats, etc., because they are made on a case-by-case basis, discharged at will, and don't commonly have names that clearly signify the proposition being claimed. We have lots of words to talk about the assumptions we make, and many of them are fairly interchangeable. In contrast "Axiom" usually holds quite a bit more weight, and is usually distinguished from the crowd of near synonyms. Things like the Peano_axioms in math, or ZFC, and most of the other things at List_of_axioms. Science just doesn't really much like that, with some vague exceptions along the lines discussed above - methodological naturalism, inductive reasoning is valid, etc. But those are so low-level that most practicing scientists don't bother mentioning them, and don't worry about whether they are operating in one context or another, as mathematicians, logicians and philosophers will do with axiomatic set theory and other fields. So this is why I wrote the bit about "broadly enough" at the very start - the hope was to focus (as I think the OP was) on a narrower sense of axiom, because otherwise the answer is a rather obvious "yes, scientists make zillions of assumptions every day, in every theory they formulate, in every hypothesis they test, in every experiment they design, and in every paper they write, and in every class they teach." SemanticMantis (talk) 19:45, 30 October 2015 (UTC)[reply]

I recognize that the question being asked here is a broad philosophical one regarding science and the empirical process in general--and many of the above responses have addressed that question quite ably--but I would add, as a practical note, that this question becomes, in terms of apparentness, more or less difficult to address in various types of scientific work or philosophical undertakings. Two areas where axiomatic thinking is notoriously challenging to avoid are theoretical physics and cognitive science. Both struggle with defining the epistemological nature of reality without reference to some first principles, be they the mathematical abstractions of physics or the intuitive metaphysics of cognitive studies. Take the solipsism of the general view of consciousness; although there are those who raise perplexing question about the assumption, the general intuitive view is that that consciousness/thought is a real phenomena, even though we have absolutely no way to quantify what exactly it is or how something so intangible arises out of the material world.

So yes, without disagreeing with the perspectives above that say that the only firm axioms science holds to are those concerning the fact that the universe does have dependable rules and that we can observe their consequences (which are fair statements when looking at the question on its broadest level), it's also true that in practice scientists at the frontiers of human understanding often have to make workable assumptions while they try to work out the mechanics of the problems they investigate to an increasingly refined level. And further, that there are some assumptions that we haven't been able to work or think ourselves past for thousands of years. Snow ^{let's rap} 19:34, 30 October 2015 (UTC)[reply]

The Scientific Method itself is essentially an axiom. How do you know you need to formulate a hypothesis before conducting an experiment? Where is the proof of that? You don't need it, it's self-evident and can be asserted without proof. Same with all of the other steps. ScienceApe (talk) 02:01, 1 November 2015 (UTC)[reply]

OP curiousMahfuzur rahman shourov (talk) 03:42, 30 October 2015 (UTC)[reply]

I think you are looking for the word: Paresthesia. Ariel. (talk) 04:36, 30 October 2015 (UTC)[reply]

OP curiousMahfuzur rahman shourov (talk) 16:32, 30 October 2015 (UTC)[reply]

[3] and [4] (may not seem the best source, but it refers albeit doesn't really link to sources like [5]). Carbonated beverage is a fairly unclear term. What applies to carbonated water, may not apply to some carbonated beverage. In particular, I imagine you could carbonate sea water and it could cause dehydration just like sea water could. But I think the evidence like [6] [7] [8] suggest that the majority of carbonated beverages contribute to hydration. That doesn't of course mean they are a great way to achieve hydration, although I think the evidence suggests carbonated water is generally not that much worse than plain water in most respects except that it may be harder to drink a lot of it. I don't know if it makes much sense to call it a pseudoscience, more a myth or superceded claim depending on precisely what you're referring to (e.g. all carbonated beverages, highly caffinated carbonated beverages. Nil Einne (talk) 17:45, 30 October 2015 (UTC)[reply]

To the extent that many carbonated beverages have caffeine in them, this is often true, caffeine being a diuretic. Snow ^{let's rap} 19:38, 30 October 2015 (UTC)[reply]

Yes, but it's only short-term stimulation of urine output, and only occurs when people haven't had caffeine for days or weeks. Conclusion was: Doses of caffeine equivalent to the amount normally found in standard servings of tea, coffee and carbonated soft drinks appear to have no diuretic action.. And when "severe" dehydration is considered, you'll always be better off drinking than not drinking. Ssscienccce (talk) 21:20, 30 October 2015 (UTC)[reply]

Well, I can't say as I didn't realize that tea and coffee (being almost entirely water) result in net hydration, but I was previously unfamiliar with that review and am surprised that the diuretic effect in doses of the sizes discussed is so limited; thanks for the source and the fix to discussion! Snow ^{let's rap} 01:06, 31 October 2015 (UTC)[reply]

Caffeine has little or no impact on hydration [9][10]. Mikenorton (talk) 21:23, 30 October 2015 (UTC)[reply]

Caffeine does increase urine output, which can have a secondary effect on hydration: Caffeine#Physical. --Jayron32 18:44, 31 October 2015 (UTC)[reply]

30-40 years ago Coca Cola had lots of caffeine and salt, presumably to make people buy even more Cola. But things have changed since then, e.g. I routinely drink Cola Zero and I have noticed no dehydration effect. Tgeorgescu (talk) 17:10, 31 October 2015 (UTC)[reply]

Did it? I'm not an expert Cokeologist, but I think the formula has remained basically the same for many decades, excepting the switch in the U.S. from cane sugar to HFCS, and the well-known and brief introduction of New Coke. "Coke [or other colas] has lots of caffeine and salt to make you thirsty" is something I hear occasionally, but it appears to not really be true. A can of Coca-Cola has 45 mg of sodium and 34 mg of caffeine, which is barely any. Coke Zero has 5 mg less of sodium, an insignificant difference. Compare to a cup of coffee, which tends to run around 100-200 mg of caffeine, depending on a lot of variables (see the caffeine article for a table of caffeine content). And as mentioned above and in the article, if you consume caffeine regularly you rapidly develop tolerance to its diuretic effect, which is fairly mild to begin with. On the other hand, alcoholic beverages can dehydrate you, because ethanol interferes with antidiuretic hormone, increasing urine output, and this effect seems to be less susceptible to tolerance. Dehydration is thought to be one of the factors that contribute to hangovers. --71.119.131.184 (talk) 00:22, 1 November 2015 (UTC)[reply]

Do dogs (and animals at all) smell fear? Does the fear has "fear molecules" that spread in the air? 21:17, 30 October 2015 (UTC) — Preceding unsigned comment added by 78.111.186.78 (talk)

I don't know - but dogs are renowned for being extremely sensitive to human body language - and my suspicion is that this is what they are really reacting to. That said, we probably do give off enough chemicals of one sort or another that the dog could also be detecting that. It's hard to say which! SteveBaker (talk) 21:35, 30 October 2015 (UTC)[reply]

Dogs are social animals. The negociate their rank with the human inside the pack. They sense what some civil education had stolen the people. --Hans Haase (有问题吗) 22:01, 30 October 2015 (UTC)[reply]

Cortisol is a likely culprit; even humans seem to be able to smell fear in other humans, according to this study [11]. Dogs can do all sorts of things. Here's a case study of a dog detecting low blood sugar in a human [12], and Seizure_response_dog has some interesting refs on some dogs being able to predict seizures in humans. As Steve says, lots of other cues aside from smell probably come in to play as well. SemanticMantis (talk) 22:18, 30 October 2015 (UTC)[reply]

If a human can smell your fear, it's time to change your underpants. StuRat (talk) 00:31, 1 November 2015 (UTC) [reply]

(edit conflict) I found plenty of "popular" articles to back up SteveBaker's suggestion - a mixture of human scent changes caused by stress and body language. See this or this for example. Alansplodge (talk) 22:20, 30 October 2015 (UTC)[reply]

Well I would be surprised if anyone had done any detailed research in this area (meaning specific to dogs and the specific mechanism by which they might perceive fear in humans. Those reports of "disease-sniffing" dogs garner some attention because they strike us as so phenomenal, but the truth is a case study here and there doesn't tell us much about what is really going on (if indeed anything other than the human tendency to see a pattern where there is none and to ascribe superhuman (supercanine?) abilities of acuity, affinity, and intuition to our animal companions. Meaning no offense to SM, undoubtedly one of our all time best scientific reference contributors here, but that particular source is pretty representative of the kind of questionable "science" that goes into these inquiries. It takes as rather for granted a phenomena that is highly questionable and can probably be explained a hundred different ways that are more likely than those being presented, to say nothing of the sample size of one and the kind of subjective "evidence" being presented (the survey it cites doesn't not sound anymore empirically valid). And then there's this gem at the end: "One other possibility may be the dogs’ detection, of energy wave changes in a person’s electrical and/or magnetic fields during a hypoglycaemic episode. This is as yet undetermined." Yeah....

Anyway, I've limited knowledge of the research surrounding dog olfaction, but I am an expert in perception broadly, with a sharp interest in it's relevance sociobiology and my instinct is that Steve probably has hit on the more likely explanation. Certainly I am generally loathe to provide speculation in place of a good source in this space, but that's my best insight anyway. Certainly we know for a fact that dogs are immensely responsive to body language -- that's an area of much more robust understanding, with regard to both intuitive observation and research. I wouldn't entirely discount the possibility of sensitivity to olfactory stimulus in this area, given the breadth of chemoreception in dogs with regard to smell, but I'd expect it to play a secondary role. In animals with decent vision and no major omnipresent predators in their ecological niche, vision almost always takes the central role in threat response, especially in particularly social species. Snow ^{let's rap} 01:40, 31 October 2015 (UTC)[reply]

Snow, I think you might have been just a little premature dismissing the low-blood sugar example. Please see Rooney, N. J., Morant, S., & Guest, C. (2013). Investigation into the value of trained glycaemia alert dogs to clients with type I diabetes. PloS one, 8(8), 1-12. [13]

People may also wish to read Cornu, J. N., Cancel-Tassin, G., Ondet, V., Girardet, C., & Cussenot, O. (2011). Olfactory detection of prostate cancer by dogs sniffing urine: a step forward in early diagnosis. European urology, 59(2), 197-201[14]DrChrissy ^(talk) 02:02, 31 October 2015 (UTC)[reply]

Perhaps I put my thoughts inartfully; my doubts are more focused on the role of olfaction in the scenario presented above than in the possibility that a pet canine may detect declining health or even be sensitive to a specific kind of physiological imbalance in someone they are familiar with. Mind you, even with regard to the later, those studies present pretty mediocre confirmation (small sample sizes, little to no control, lack of firm understanding for the mechanisms involved, and a whole host of other issues which limit the observations we can make here. But all of that said, I don't doubt that dogs pick up on changes of the well being in their companions; I just find the research in the specifics a little underwhelming at this stage. Note also that there are two different kinds of phenomena being discussed here: A) undirected (and often socially influenced) perception of a vague change, 1) by the canine, 2) as to the physiology of the human, and often observed to some extent by the human, who often is the subject of the experience, close to the other subject (the dog) and often is not someone of scientific background, and B) a trained response to a specific stimuli. I don't doubt in the least that a dog can be trained to sniff out a stimulus that is predictive of cancer in urine; that's completely non-controversial and unsurprising to me, as dogs can be trained to detect a wide range of olfactory stimuli. But that's an entirely different matter from saying "My king charles spaniel is a living glucometer, who can smell my blood sugar and read my magnetic aura!" Snow ^{let's rap} 02:27, 31 October 2015 (UTC)[reply]

Snow, you appear to be lumping all studies in this area into one basket and saying they are all rubbish. The first one presented has "case study" in the title so we are all fore-warned about the potential for a lack of extrapolation. However, the two other studies I put forward are considerably more robust and don't even mention magnetic aura! Are you saying that your criticisms above apply to these two studies?DrChrissy ^(talk) 20:38, 31 October 2015 (UTC)[reply]

Well I'm not presuming all possible studies in this area will suffer from the above shortcomings, and certainly the spaniel comment at the end of my post was directed at the case study, but if pushed to give an evaluation of the empirical rigor of the other papers, then my impression is not really all that much better. Let's take the PLOS One study. It has a small sample size, it relies on self-reporting by the subjects, it proposes no mechanism for how the dogs supposedly perceive the low blood sugar, it omits any discussion whatsoever of the methodology by which the dogs were "trained", its statistical results are pretty mediocre, and it has pretty much zero control along, oh about a bazillion factors that could skew the results here.

All observations were conducted by lay people and most of the dogs were owned by the subjects prior to their training for this task. That they had an (ever so slight) uptake in how often they caught their unabalanced blood sugars (which, despite some red herrings in the way the study is written, is the only statistical assertion it claims to make) after their pets were trained (or they received the new pet) could mean just about anything. The fact that they now believe that they have a glucose-detecting wonder dog could cause them to check more frequently. And whatever the training regimen was like, it could not have been too demanding and particular, looking at how the dogs "alerted" their owners: "stare, paw, and sometimes grunts"; "yawn, tap me, and stay with me"; "agitated then stares"; squaek and stay with me, if other person is present alerts them though not trained to" [emphasis added]; "jumps up, licks, sits next to". On top of all of this ambiguity, those conducting the experiment apparently encouraged the (human) participants to reward their dogs for alerting them. I need hardly tell any scientist (or indeed any person who has ever had a dog) how this might confuse the results. Even the a authors, when trying to account for the statistical variations that would otherwise complicate their conclusions, concede the problems here (but then proceed to dismiss this glaring issue under a pretty laughable assumption: "Since the data is owner-reported, it is also possible that a belief in their dogs’ ability led some owners, consciously or inadvertently, to be more likely to record ambiguous behaviours as alerts only when their sugars were subsequently found to be low, as compared to normal, or to conduct routine tests, when they were likely to be in within target range. However clients were made aware that records were also to be used to detect training issues and to direct remedial training, so we believe this risk was mitigated and it is extremely unlikely that all clients were biased."

And I've barely scratched the surface on the likely conflating factors, lackluster methodology, and ambiguous results here. I could easily go all day discussing why the conclusions reached are dubious. So yes, while I was trying not to be so strident on the matter, since you've put me in the hot seat, I find this to be a very weak study, full of issues and devoid of much compelling empirical value. But let's assume, just for the sake of bringing discussion back around to the main issue of this thread, that we accept that the dogs are perceiving when the blood sugars of their human companions have entered into a dangerous range. That still would not mean they were smelling it. It might be any of a huge range of changes in the condition of their owner that they were responding to.

As to the study on dogs sniffing for stimulants indicative of cancer in urine, I have not really reviewed it, but as I said before, I've little doubt that this can be accomplished and, in any event, that kind of study can be conducted in a much more straight-forward and controlled fashion. In fact, though I don't recall the specifics, I've seen research in this area before and don't remember coming away with a bad impression of the methodology. Snow ^{let's rap} 00:30, 1 November 2015 (UTC)[reply]

Meh, It's no offense to me that a case study is not grounds for scientific, mechanistic understanding, that's why I clearly called it that. What do you think about the humans smelling fear in humans article? I just skimmed it, but the discussion seemed very adamant that cortisol was both involved but also not the only factor. I was thinking that if we have good evidence that some humans can sense some human fear via olfaction, then it doesn't stretchy my credulity to think that dogs can too. After all, they generally have olfactory detection far superior to ours, cortisol and similar compounds are used similarly and widely throughout mammalia, and we've been selectively breeding dogs that can better understand us for a very long time ;) SemanticMantis (talk) 16:41, 31 October 2015 (UTC)[reply]

Me too. the point I was making above was that if a dog can be trained to indicate the odour of something, it can obviously smell it. I think the case of smelling cancer may in fact be far more surprising than SNOW predicts to people less widely read than SNOW. Don't forget, the OP question was "Do dogs smell fear". My gut-reaction would be that I think it is likely, but, I would want to see some robust evidence for it before making a definitive statement. Speaking of case studies, a woman's apparent ability to smell Parkinson's hit the news this week in the UK.[15] A case-study, yes, but it does start us thinking.DrChrissy ^(talk) 16:51, 31 October 2015 (UTC)[reply]

I have read many anatomy books, and also the article here (vertebra) and I am still confused and don't understand what the difference is. 78.111.186.78 (talk) 13:13, 31 October 2015 (UTC)[reply]

The picture to the right, from the Wikipedia article vertebra, should make it a bit clearer. The vertebra consists of two parts: the body (the big heavy semicircular chunk of bone at the top of the picture) and the arch (all the rest of it, with the little pointy bits all over it). The two main connecting parts of the arch are the pedicle (which connects the arch to the body, there are two of them) and the lamina (which connects all the pointy bits to each other). The space enclosed by the body, the two pedicles, and the lamina are the 4 sides of the spinal canal. --Jayron32 14:10, 31 October 2015 (UTC)[reply]

Thanks. So when I see in professional books anterior and posterior arch is replace (or instead of) the names Lamina and Pedicle? (By the way, forr your method there are 5 sides of the spinal canal. 1th is the body, 2nd+3rd are the pedicle, 4th+5th are the laminae) — Preceding unsigned comment added by 78.111.186.78 (talk) 15:35, 31 October 2015 (UTC)[reply]

Yeah, that works too. --Jayron32 18:42, 31 October 2015 (UTC)[reply]

If it helps you make sense of the term, "pedicel" basically is just a technical term for thin stemlike things, and is used in lots of places (with slightly variable spelling), e.g. Pedicel_(botany). SemanticMantis (talk) 16:37, 31 October 2015 (UTC)[reply]

What are the uses of Jasper conglomerate? Is it useful to humans? --Doeskmaesk (talk) 19:20, 31 October 2015 (UTC)[reply]

Some conglomerates are used as building stones, and I imagine that the clasts of jasper would be attractive, but there are often issues with cutting such rocks, as the matrix is often softer than the clasts, making it difficult to get a good flat surface. Apart from that I have no idea how it might be used. Mikenorton (talk) 21:20, 31 October 2015 (UTC)[reply]

I imagine attractive pieces could be used as paperweights, doorstops, or bookends. Grinding rather than cutting might be the best way to shape it. (You might think it could be used as concrete, but the cost and inability to pour it into molds would make this use unlikely.) StuRat (talk) 00:35, 1 November 2015 (UTC)[reply]

I've not seen Jasper conglomerate myself, but a similar stone, known as Roxbury Puddingstone has been used as a building material in the Boston, Massachusetts area for centuries. --Jayron32 01:08, 1 November 2015 (UTC)[reply]

Can a 40 feet transit bus fit into a wide-body aircraft such as the Airbus A330, Airbus A380, Boeing 747, or Boeing 777 as cargo? For example, could a 40 foot transit bus manufactured by Gillig or New Flyer fit into an Airbus A380, the world's largest passenger airliner if the aircraft was converted to a cargo only aircraft? WJetChao (talk) 08:15, 1 November 2015 (UTC)[reply]

Hello WJetChao. There are many websites with dimensions on bus widths and many others with cargo aircraft door widths. Large busses are 2.5 to 2.6 meters wide. Large cargo aircraft have loading doors that average 3.4 to 3.5 meters wide, though some are much wider. Accordingly, most busses can easily fit into large modern cargo aircraft. Cullen³²⁸ Let's discuss it 08:46, 1 November 2015 (UTC)[reply]

Not so fast, there, Grasshopper. Er, Dolphin. Some leaping creature, anyway.

I took as an example the New Flyer Excelsior bus and the Boeing 747-400 family freighter. As Dolphin says, the cargo door width is not a problem, and neither are the length or the weight. But the height is. The cargo door opening at the front of the plane is only 2.49 m high (98 inches); see page 18. Even the side door, which I suspect would not be workable with an object the length of a bus, is only 3.1 m high (123 inches); see page 15. Without doing something special you could not put this bus, which is at least 3.2 m high, onto this plane. The problem, of course, is partly that it's taller than a standard shipping container. I haven't looked at the other planes the OP mentioned; maybe one of them will take it. --70.49.170.168 (talk) 11:50, 1 November 2015 (UTC)[reply]

It would fit on top of a Boeing 747 Shuttle Carrier Aircraft, but that's probably cheating. Alansplodge (talk) 14:59, 1 November 2015 (UTC)[reply]

I'm surprised that we don't have an article (or a redirect) for chemical notation. Or where would we have definition of parentheses, as in "Al(l)"? BTW, the reason I needed to look this up was because of this edit, which looks like a good faith misunderstanding to me. — Sebastian 08:50, 1 November 2015 (UTC)[reply]

See Chemical equation and look under Common symbols. We also have Chemical formula and Chemical nomenclature. Dolphin (t) 09:06, 1 November 2015 (UTC)[reply]

In the modern era of the digital/technological age, why does intelligence fail? Surely digital capabilities should improve intelligence capabilities? --Copstwurst (talk) 09:52, 1 November 2015 (UTC)[reply]

This is a Humanities question, not science. "Intelligence failure" doesn't mean that the microphones broke down or the drones shut off their transponders and flew toward Antarctica. It means that spies (the people we hire to spend their lives lying and deceiving people) didn't tell us the truth. Was Nigerian yellowcake an intelligence failure, or an intelligence success? Depends on whether the spies' purpose is tell Americans the truth, or start the war the President's family wanted. Wnt (talk) 11:57, 1 November 2015 (UTC)[reply]

@Copswurst: intelligence and measures of are human constructs, facilitates Illusion of control, explored in Philosophical zombie, Simulacrum, technology reduce pressure on brain to process, memorize viaRed queen hypothesisMahfuzur rahman shourov (talk) 15:18, 1 November 2015 (UTC) @Copstwurst:mention correctMahfuzur rahman shourov (talk) 15:19, 1 November 2015 (UTC)[reply]

I was making up a chart at neutron reflectometry recently, noticing the variation between elements in coherent scattering, incoherent scattering, and absorption. The neutrons can penetrate tens of millimeters into many materials. It is possible to use specular reflection for crystallography, but often at high angles there is simply random scattering. Still...

What would common landscapes - people, forests, houses - look like as illuminated by a neutron source? (Assuming either that you can detect at very low 'illumination', or can see the result of an instantaneous flash, like a Hiroshima bomb) At first I would think that everything would be just kind of white, from random backscatter, except that some materials absorb more than others, and I'm not sure how the coherent reflections would affect an ordinary photograph.

But there is also a matter of wavelength. The numbers I put in that paper were for neutrons with 1 angstrom or perhaps 1.8 angstrom wavelengths and seemed quite consistent, but in theory neutrons can have all sorts of wavelengths. And scattered back, their wavelengths should change from the recoil. So I'm thinking there ought to be such a thing as color neutron photography.

Is there a sense of this out in the literature somewhere? I wonder if the world seen by neutrons is as beautiful as by photons' light. Wnt (talk) 12:20, 1 November 2015 (UTC)[reply]

Does registration for professional status after getting an engineering major take a significant amount of time outside working hours? — Preceding unsigned comment added by Clover345 (talk • contribs) 15:08, 1 November 2015 (UTC)[reply]