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September 7

Distance of electron from Hydrogen Nucleus

I have another question from my inorganic textbook. From reading the text, I more or less know what they want me to say. In its ground state, hydrogen's single electron will be in the 1s orbital. The answer to a) is that the electron's most probable location is where the radial probability density is highest (i.e. the square of the radial wave function). From this graph in the text (where the radial probability density is denoted R²), it's clear that the highest probability is at the nucleus itself. For part b) the question is asking about the radial distribution function (drawn in red in the same graph), which has a maximum at the point equal to the Bohr radius (52.9pm) on the nuclear charge (1 for hydrogen, so the answer is 52.9pm). Even though I'm pretty sure I know what they want me to say, I don't understand what it means. How can the most probable distance be 52.9pm from the nucleus when the most probable location is the nucleus itself? What does that actually mean? Is it something like "The most probable distance is 52.9pm in any direction from the nucleus, so the most probable location is the average of those points i.e. in the center"?

Also, the text gives me this relationship for determining the maximum of the radial distribution function. But it only seems to be for 1s electrons. The accompanying text notes that the number should be higher for higher n values, but there's nowhere to actually plug in n, and I need to determine the value for n=2 to solve part c) What is the most probable distance of a 2s electron from the nucleus? 202.155.85.18 (talk) 09:31, 7 September 2018 (UTC) EDIT: Actually, they also give me this graph in the text. Perhaps I'm just supposed to read off that the maximum of a 2s orbital's radial distribution function is a tiny bit over 2x the Bohr radius and leave it at that? Googling around there are some tutorials for physics students explaining how to actually determine the 2s RDF numerically and then find the maximum, but I'm fairly sure I'm not meant to be able to do that given this passage in the text. 202.155.85.18 (talk) 09:41, 7 September 2018 (UTC)

this page has a discussion of the derivations of the various radii in question. --Jayron32 11:32, 7 September 2018 (UTC)

Mistake in article

In Apollo 11, it says "Aldrin joined him about 20 minutes later". In Buzz Aldrin: "Aldrin set foot on the Moon at 03:15:16 on July 21, 1969 (UTC), 9 minutes after Armstrong first touched the surface".111.235.89.222 (talk) 11:34, 7 September 2018 (UTC)

I reviewed the details, and I'm comfortable with using the vague language, "about 20 minutes later," because the article introduction is only providing an abbreviated summary.

One of the best resources for factual details of the Apollo lunar missions is the Apollo Lunar Surface Journal. Here's the transcript for Armstrong and Aldrin during the first extravehicular activity on the moon's surface.

Ultimately, both astronauts got on the moon within "about" twenty minutes, depending on how you count - the procedures for the very first moon landing were complicated. The process of exiting the Lunar Module - just "walking out the door" - actually took several minutes. Here are Page 40 and Page 41 of the EVA checklist.

I think it's alright for our article's lead paragraph to say "twenty minutes" - readers who want more details about precisely what was going on during that time can find such details in the rest of the article and in the primary sources referenced by the article. Nimur (talk) 14:13, 7 September 2018 (UTC)

I looked at the Lunar Surface Journal (linked above), and Armstrong stepped onto the Moon at about 109:24:20, mission elapsed time. Aldrin is on the LM footpad about 109:42, but he sets foot on the Moon about 109:44, so "20 minutes later" is good. Bubba73 ^{You talkin' to me?} 15:43, 7 September 2018 (UTC)

Efficient swimming: horizontal or vertical fin

Does it make any difference, even if it's a small one, whether a marine animal (imagine dolphin vs shark) has its tail fin attached horizontally or vertically? Obviously, there's an ergonomic difference. Humans will have a hard time flapping a fin horizontally. I ask discounting such issues. --Doroletho (talk) 13:50, 7 September 2018 (UTC)

Without addressing the more general scenario I would observe that, close to the surface, a horizontal fin (i.e. one moving up and down) could waste some of its energy by causing splashes where a vertical (side-to-side) fin would not. However, IANAHydrodynamicist. {The poster formerly known as 87.81.230.195} 2.122.60.253 (talk) 14:56, 7 September 2018 (UTC)

Ignoring issues of when fish break the surface or when they are skimming the bed, the orientation of the caudal fin (tail fin) is irrelevant. It isn't about orientation. It is about movement. Fish flex side-to-side, not up and down. It is how the spine and muscles are arranged. Sea mammals flex up and down, so they have horizontal fins. 216.59.42.36 (talk) 15:43, 7 September 2018 (UTC)

I think it evident that Doroletho knows this, and addressed it by mentioning ergonomics. I understand the query to be whether there is any inherent propulsive advantage, assuming perfected body design in either case, of a vertical tail fin over a horizontal one or vice-versa. I would have thought not, but as previously mentioned IANAH.

It occurs to me that one circumstance where it might make a difference is if our hypothetical entity needs to change directions more often or more quickly in a horizontal plane (changing direction) or a vertical one (diving or ascending), since a caudal fin is generally larger, stronger and (by virtue of its position) has more leverage than more "inboard" fins like pectoral, pelvic, etc.

Our articles Fish locomotion and Aquatic locomotion might contain material of some relevance. {The poster formerly known as 87.81.230.195} 2.122.60.253 (talk) 19:24, 7 September 2018 (UTC)

Animals that need to surface and dive have horizontal tails for the movement to and from the surface. Animals that breathe underwater have vertical tails. — Preceding unsigned comment added by 68.191.203.98 (talk) 21:07, 7 September 2018 (UTC)

It would be a mistake to attribute all of this to what makes the most sense given an animal's lifestyle, without considering evolution, as was discussed above you. It makes just as much sense for lifestyle to follow from forms and functions that are already available. Fish spines flex in the left-right axis, while mammalian spines flex in the dorsal-ventral axis. There are fish with horizontal tails, from the perspective of someone perpendicular to the ground: flatfish. They actually move with one side facing down, and one facing up, but their bodies are strikingly asymmetrical in the left-right axis, giving a functional top and bottom. Someguy1221 (talk) 22:42, 7 September 2018 (UTC)

Googling the subject indicates that the fastest fish are faster than the fastest mammals - but not by a whole lot. ←Baseball Bugs ^{What's up, Doc?} carrots→ 23:53, 7 September 2018 (UTC)

I think the fastest species in water is the Marlin, reaching speeds of up to 80 km/h (50 mph). They have a very thin, long body tho, so it would be unfair to compare them with the much more "bulky" Dolphins, who manage 55 km/h (35 mph) with different fins. In fluid dynamics it does not make a difference. Besides Dolphins are so smart, they would probably start swimming tilted to 90 degrees if that would give them a speed advantage. --Kharon (talk) 07:04, 9 September 2018 (UTC)

September 8

Forest planets and city planets

I know lately that astronomers talk about ocean planets, iron planets, ice planets, and lava planets and are mentioned in scientific journals. I also believe there exists forest planets and city planets such as seen in science fiction. But why haven't the possibilities of forest planets and city planets seriously considered by astronomers and mentioned in journals? (though I've seen one mention of forest planets when talking about observing fingerprint of red edge vegetation using spectra) Forest planets provide evidence of complex vegetation on the surface, while city planets have evidence of intelligent civilization. Forest planets would have trees that cover most (but not all) of the planet's surface, while city planets have urban areas that cover much of the surface. PlanetStar 03:15, 8 September 2018 (UTC)

Wouldn't either of those just be terrestrial planets? 139.194.67.236 (talk) 03:42, 8 September 2018 (UTC)

Although evidence + speculation = theory,^[me] speculation is the realm of science fiction and evidence is the realm of science journals. I'm sure, however, that astronomers and astrophysicists discuss such things around the water cooler (so to speak). 107.15.157.44 (talk) 04:33, 8 September 2018 (UTC)

A "forest planet" is unlikely to exist, unless you significantly dilute the definition of "forest". It would require most of a planet's land to be covered by a certain type of life, regardless of variations in climate, terrain, etc. To look at our single example, Earth, trees can't thrive where it's too arid, or it gets too much below freezing for too long, or the soil is unsuitable. Even in some of these habitats where it's possible to grow certain trees (e.g., grasslands), other organisms out-compete them because they're better-adapted. A ecumenopolis is hypothetically possible, but efforts to detect other planets will naturally focus on the more likely scenario (as here on Earth) of large urban areas, but not ones covering the entire planet.

The examples you've given are the result of processes not involving life, and these processes are fairly well-understood, most with examples in our own Solar System: ice planet, ocean planet, iron planet, lava planet. --47.146.63.87 (talk) 06:24, 8 September 2018 (UTC)

I believe forest planets do exist, albeit rarely. Our galaxy contains billions of planets, at least few of those are forest planets. Naturally making into forest planets with trees or tree-like organisms growing over much of the surface are naturally difficult but not impossible. Forest planets can still have mountains, deserts, savannahs, bodies of water, and ice fields and glaciers, albeit covering substantially less than 50% of the planet in total. Several forest planets are seen in science fiction, including Dagobah and Endor (moon) in Star Wars. A related type is jungle planet, which would have jungles covering more than 50% of the planet's surface. I believe city planets like Coruscant are even more rare than forest planets and jungle planets. PlanetStar 02:12, 9 September 2018 (UTC)

Well sure, if you define "forest planet" as simply "any planet with more than 50% of land occupied by forest", such planets are more likely. I think "forest planet" in science fiction generally implies near-total coverage. Earth has 30% of land occupied by forest, so we're not too far from being a forest planet under that definition. --47.146.63.87 (talk) 07:05, 9 September 2018 (UTC)

How many of the earth's trees can be seen from the earth's moon? ←Baseball Bugs ^{What's up, Doc?} carrots→ 11:19, 8 September 2018 (UTC)

None individually, but attempts at analyzing exoplanets don't involve trying to spot trees through a telescope, which is impossible, but tools such as spectroscopic analysis. If there are lots of photosynthetic organisms that absorb certain wavelengths of light, that will cause an effect that may be detectable. Another smoking gun would be the presence of free oxygen in the atmosphere, which is also detectable through spectroscopy. --47.146.63.87 (talk) 07:05, 9 September 2018 (UTC)

If a planet were covered in trees, where would they get their water? ←Baseball Bugs ^{What's up, Doc?} carrots→ 10:55, 9 September 2018 (UTC)

From rain, deriving ultimately from the planet's oceans. I don't think anyone (else) in this discussion is envisaging a planetary surface 100% covered by forested land, but rather a planet whose land surface is so covered. If that land surface were confined to the temperate, tropical (in the geographical sense) and equatorial zones, with the Polar regions landless, 100% forest land cover seems feasible – I suspect even Earth has been in such a state for some periods in the past, such as during parts of the Devonian.

Then again, there's also Kelp forest.

Nor need we restrict our thought to planetary atmospheres, climates and ecosystems closely resembling Earth's. A somewhat denser atmosphere with a different composition, different patterns of circulation, and forms of life completely unrelated to ours could perhaps plausibly combine to allow "forests" at all latitudes – where's Hal Clement when we need him? {The poster formerly known as 87.81.230.195} 2.122.60.253 (talk) 00:16, 10 September 2018 (UTC)

Here are a few famous writings by actual scientists:

• Search for Artificial Stellar Sources of Infrared Radiation, (Freeman Dyson, Science, 1960)
• Pale Blue Dot (Carl Sagan, 1994).

Both of these are scientific evaluations that detail how planets appear from very far away. The short summary is that at astronomical distances, there is almost no way to reasonably measure or observe the presence of life - even if it manifests on a planetary scale as an Earth-like forest or city. The primary method we might reasonably use to detect life on other worlds would be analysis of the electromagnetic absorption and emission spectra of a planet or a star. One of the main efforts in the search for extraterrestrial intelligence is to characterize natural astrophysical electromagnetic emissions - radio astronomy - so that we might some day recognize an anomalous signal, if there is any such signal to be observed anywhere in our universe.

Nimur (talk) 01:36, 11 September 2018 (UTC)

Where is Dnieper arising from? Is its origin considered a wellspring?

Dnieper river is one of the impressive rivers of eastern Europe that goes through 3 countries: Russia, Belarus and Ukraine. My question is where does this river arising from? The article (Dnieper) here says that it is arising from Valdai Hills in Russia. What does it mean? Does it mean that its origin is a wellspring in fact? (I tried to find a picture of Dnieper's origin but I didn't find it.). I'm trying to understand what gives a supply of water to Dnieper, is it rain that directly falls on Dnieper or around it, or is it a huge wellspring in Valdai Hills in Russia that gives it its capacity?93.126.116.89 (talk) 05:14, 8 September 2018 (UTC)

If you read the article you linked to you would know that the source of the Dnieper is the sedge bogs (Akseninsky Mokh) of the Valdai Hills in central Russia.. The article includes a reference which will lead you to [1] which confirms this: The source of the Dnipro lies in the northwest part of the Central Upland—in the Valdai Upland, at an elevation of 220 m, among turf swamps.. So the answer to your question is that the river's source is in bogs or swamps, not a spring. Bazza (talk) 12:17, 8 September 2018 (UTC)

Request article review: Levonorgestrel

Our article on Levonorgestrel is likely to be in the news in the next few days, based upon this news story:[2]

I would like to request a review of the article and its sourcing to make sure that everything is accurate.

When it comes to medical topics, an electronics engineer like myself is pretty much lost (I have this mental picture of a non-engineer M.D. trying to "fix" our Cockcroft–Walton generator or Hall effect articles...), but the following quote from a citation in the article seems to my untrained eye be in conflict with WP:MEDRS, even though the source seems otherwise reliable.

"In 2002, a judicial review ruled that pregnancy begins at implantation, not fertilisation"

As I said, I have zero expertise here and am making no suggestions for specific changes. Its just that the above quote looks more political than medical to me. I just think medical questions should be answered through research, not judges and juries. --Guy Macon (talk) 14:32, 8 September 2018 (UTC)

Our article describes some debate over whether there might be a post-fertilization effect. If there is one it is not the major effect, but understandably those who think life begins at conception will be appalled at the possibility. I have not done enough review - if it is possible at all - to tell if one point of view can be relegated to a fringe theory. Wnt (talk) 16:27, 8 September 2018 (UTC)

The article on emergency contraception though says several times that there is no post-fertillization effect and stresses the distinction between emergency contraceptives and abortifacients . Despite what the article says though at least one abortifacient, mifepristone, is also prescribed as an emergency contraceptive. Additionally, it notes that copper based spermicides almost certainly have abortive properties. 139.194.65.208 (talk) 03:04, 9 September 2018 (UTC)

Perhaps we need to take a close look at that article to make sure that the claims are backed up with WP:MEDRS compliant sources. The article claims:

"The best available evidence is that they do not have any post-fertilization effects such as the prevention of implantation"

But one of the sources cited in the article says

"To make an informed choice, women must know that ECPs—like the birth control pill, patch, ring, shot, and implant,76 and even like breastfeeding77—prevent pregnancy primarily by delaying or inhibiting ovulation and inhibiting fertilization, but may at times inhibit implantation of a fertilized egg in the endometrium".

I have no strong opinions on this topic, but I can understand why a religious person who believe as part of their religion that anything that gets between initial egg fertilization and delivery of a baby is a form of murder would be concerned. --Guy Macon (talk) 04:10, 10 September 2018 (UTC)

Honestly, reading the emergency contraception article it feels like it's imbued with a fairly deep ideological tinge, and doesn't adhere to WP:NPOV, but I'm sure my own POV is influencing that feeling. 202.155.85.18 (talk) 08:32, 10 September 2018 (UTC)

Seeing this debate, I took it to PubMed and came up with this review. They cite one study which found "There is no significant difference in the attachment of embryos following treatment with UPA compared with controls and no observable degenerative changes in the embryos." They cite another two studies which finds "After 13 week of UPA treatment, the glandular epithelium appeared inactive, the glandular architecture was altered, and abnormal stromal vessels were also often observed." However, the reviewers say "Thirdly, the authors that showed an endometrial suppression after treatment with the same SPRM utilized for treatment of myomas (Williams et al., 2012) did not demonstrate that this is also true for the UPA dosage utilized for EC."

It would seem like a reduction in implantation that is only 'significant' at higher doses than used, and which only affects fertilized embryos that are prevented by the true contraceptive effect, would be insignificant. Then again, religious people do things like separate their entire kitchen utensils into those used with meat and those used with milk based on the fear that they might accidentally boil a lamb in traces of its mother's milk, so I can kind of see how the doctrine of insignificant 'murder' might not be accepted. Wnt (talk) 13:16, 13 September 2018 (UTC)

Meth mouth, "krokodil", and phosphorus

I was just watching a documentary on the remarkable nasty effects of Russian homemade desocodeinedesomorphine, called "krokodil" because the users' skin becomes badly infected and scarred. There is a good article about it here; the photos are intense. Apparently it is made the same way, the "Nagai route", as methamphetamine, which has been blamed for "meth mouth". Both can involve phossy jaw, a syndrome initially encountered from white phosphorus contamination of workers. White phosphorus causes that syndrome via its conversion to bisphosphonates, one very similar to a drug used to treat osteoporosis (in milder dosage!) [3]

Now what's confusing me is -- what is the harmful substance that gets into the victims? (Aside perhaps from whatever the "krokodil" does to injection sites on the skin, most likely, which might be something as simple as acid-base) I mean, I've mulled over a few ideas...

1. Red phosphorus. Lots of it is left in the homemade reactions, and users consume it. Problem: red phosphorus is supposed to be pretty much nontoxic as far as I know, which is why you find it on matchboxes or even inhaled.

2. White phosphorus back reaction. I was thinking maybe somehow the red phosphorus reaction could equilibrate backward and deposit white phosphorus as part of an equilibrium. The problem is, the Nagai route as far as I know goes from 2 P (polymeric) + 3 I2 -> 2 PI3 and PI3 + H2O -> PI(OH)2 + HI etc. until all the hydriodic acid is released. The first reaction is not reversible and the second quickly destroys the possibility of the product to go backward anyway.

3. Direct bisphosphonate production. According to that source above, white phosphorus can react inside the body to form bisphosphonates. So can the red phosphorus, under clandestine reaction conditions, form some kind of bisphosphonate with the organic compounds in solution? Problem: I'd have thought that this contaminant would be found in forensic analyses of the drugs.... though that might also be true of any other idea.

4. "Leftover" white phosphorus. The structure of red phosphorus is supposed to be amorphous. Is it possible that reacting it with iodine leaves over some tetrahedra, because they might be somewhat better "leaving groups" than the other potential units of red phosphorus, so that some is converted to white phosphorus after all?

I feel like someone should have worked this out, or at least that it can be worked out with the data available. There are methods like treatment with copper sulfate and silver nitrate that can decontaminate white phosphorus even on skin [4] and so I wonder if they could also be applied to users or to the drugs before their consumption. Similarly, bisphosphonate would be expected to adhere to bone, so filtering through ground bone might remove it. Of course, I have no idea either is true. Wnt (talk) 17:06, 8 September 2018 (UTC)

You are mistaken: "krokodil" is desomorphine, not desocodeine. Ruslik_Zero 19:03, 8 September 2018 (UTC)

Sorry! I looted that article for a figure to put in the other (it's on the synthesis pathway) and managed to confuse myself. ;) Wnt (talk) 12:56, 9 September 2018 (UTC)

The first article linked by Ruslik0 has a section on this specific question: Desomorphine#Toxicity_of_"krokodil". It claims:

Causes of this damage are from iodine and phosphorus (and other toxic substances) that are present after synthesis. Addicts often use readily available but relatively toxic and impure solvents such as gasoline or paint thinner during the reaction scheme, without adequately removing them afterwards before injection. Strong acids and bases such as hydrochloric acid and sodium hydroxide are also employed without measuring pH of the final solution and analysis of leftover solutions of "krokodil" in used syringes showed the pH was typically less than 3 (i.e. as acidic as lemon juice). Failure to remove insoluble fillers and binding aids from the codeine tablets used as starting material, as well as co-administration with pharmaceuticals such as tropicamide and tianeptine, are also cited as possible contributors to the high toxicity observed in users.

There's no inline cite for this para so it's hard to tell which of the sources is being used, but there are some for the section so it may be there.

On a side note, I would just point out that the relative non-toxicity of red phosphorus, compared to white phosphorus, doesn't necessarily make it a good idea to inject it. Hope that's not "medical advice". --Trovatore (talk) 22:01, 8 September 2018 (UTC)

I would imagine that even if meth mouth is in part due to the fact that the users are inhaling phosphorus, injecting phosphorus would have different effects most likely not localized to the mouth. That's obviously pure speculation though. 139.194.67.236 (talk) 22:15, 8 September 2018 (UTC)

You still get meth mouth if you inject.

"[Meth] users can go from having a sparkling smile to one of decay and tooth loss in about a year. For one, the drug dries out a person's salivary glands leading to the cottony-mouth feeling. Without the diluting effects of saliva, the acids in your mouth--produced by various foods and bacteria--begin to eat away tooth enamel.

Adding fuel to this mouth decay, meth users may forget to brush their teeth. Whereas the effects of cocaine last about an hour, a meth high can linger for 12 hours. During this half-day high, personal hygiene may not be at the top of the list of things to do.

The extensive tooth decay of meth mouth is attributed to the drug's dry-mouth effect and its propensity to cause cravings for high-calorie carbonated beverages, tooth grinding and clenching, and extended periods of poor oral hygiene"[5]

I know, that's why I was specific to the effects of phosphorus, assuming there are any. In everything I've read on the matter previously, meth mouth was attributed to the dry mouth, teeth grinding and poor hygiene you mentioned. I've never heard of phosphorus being involved. 139.194.65.208 (talk) 02:58, 9 September 2018 (UTC)

The same article also implies that pure desomorphine injected with a sterile syringe will be relatively harmless though highly addictive. People can live for decades injecting it regularly. Ruslik_Zero 20:47, 9 September 2018 (UTC)

The same is true of all opioids routinely used in humans (whether injected or otherwise administered). Opioid overdoses are usually the result of 1) administration of impure or uncertain quantities of drug(s), as in street drugs which are usually contaminated, or may not even be the purported substance; 2) co-administration with other drugs like benzodiazepenes or alcohol. --47.146.63.87 (talk) 07:58, 11 September 2018 (UTC)

During evolution what was the fovea good for?

Modern humans use the fovea for reading and driving. This can be extracted from the corresponding article. But all this time before the invention of writing systems or cars, what was the fovea good for? Shouldn't this go into the article? — Preceding unsigned comment added by 31.4.141.17 (talk) 22:48, 8 September 2018 (UTC)

Does our article on Evolution of the eye answer your question? --Guy Macon (talk) 22:52, 8 September 2018 (UTC)

The word "Fovea" does not appear in that article. ←Baseball Bugs ^{What's up, Doc?} carrots→ 23:45, 8 September 2018 (UTC)

No, it does not. 31.4.141.17 (talk) 01:27, 9 September 2018 (UTC)

The existence of the fovea is implied in the discussion about the development of the lens. A lens to focus fine details and a part of the eye optimized for seeing those fine details go hand in hand.

As for the implied question "why is sharp vision better than blurry vision", it help one to find prey, fruit, etc that is far away, it stops you from bedding down on an anthill, and it helps in recognizing facial expressions, especially from across the room cave. --Guy Macon (talk) 01:56, 9 September 2018 (UTC)

One might argue that the fovea saves having to devote as much brain volume to processing vision as have a whole retina that was as sharp as a fovea. Abductive (reasoning) 03:11, 9 September 2018 (UTC)

The fovea has curiously been gained and lost several times in the evolution of animals. I recommend this article: [6]. Someguy1221 (talk) 05:45, 9 September 2018 (UTC)

The reason, the article (Fovea centralis?) does not go to deep into the general use from evolutionary perspective, may be that it would be to speculative. There is some hint towards hunting since the anterior lateral eyes of jumping spiders seem to be of similar function but with a very different construction. Like many other carnivores they also have the (focusing) eyes aligned for a rather limited, pure frontal field of view compared to most herbivores who have their eyes on the sides to achieve an almost completely field of view all around them, so predators can not openly sneak up on them. --Kharon (talk) 06:13, 9 September 2018 (UTC)

September 9

Brainstem removal

I read lots of people had half their brain removed, some right and some left. Yet they are still conscious. I'm almost certainly sure whatever consciousness is, has got to do with the brainstem, and the hemispheres are only for the contents of consciousness. Have there been people with brainstem removed and still alive? — Preceding unsigned comment added by Money is tight (talk • contribs) 00:07, 9 September 2018 (UTC)

• Brainstem death. Abductive (reasoning) 03:07, 9 September 2018 (UTC)

You are wrong. The Brainstem is actually responsible for autonomic (involuntary) functions. The consciousness or intellectual capacity seems to happen in the outer surface, especially with the brains windings that achieve much more surface, developed most in species regarded as very intelligent/conscious, like primates or dolphins. --Kharon (talk) 06:37, 9 September 2018 (UTC)

Presumably you are referring to hemispherectomy. This consists of the removal of one of the cerebral hemispheres, not simply "cutting the brain in half". This is an important distinction. Any significant brainstem trauma generally results in severe disability, coma, or death. --47.146.63.87 (talk) 06:51, 9 September 2018 (UTC)

Damage to the brain stem has so devastating consequences because it is responsible for arousal. Being responsible for autonomic functions does not dismiss its importance to consciousness,

BTW, contrary to Kharon's supposition above. Consciousness implies being physiologically alert, awake, and attentive (that is, what arousal is). Not much can be done without these.Doroletho (talk) 17:57, 9 September 2018 (UTC)

There's a distinction between phenomenal consciousness and "access consciousness". You are phenomenally conscious, for example, when you're dreaming, even though you are not awake or attentive. --Trovatore (talk) 21:29, 9 September 2018 (UTC)

dose testing

In drug trials, as I (mis)understand, only one dosage is typically used, occasionally two. Why not give each subject a different dose, scattered between zero and the safe limit, so as to learn about the shape of the dose-response curve? —Tamfang (talk) 08:43, 9 September 2018 (UTC)

Because that would be useless, see statistics, sample size and statistical power. As everyone is different, you need to know the effects of a dose across a range of subjects to get meaningful results. Something which is sort of what you're talking about and which is sometimes done in phase 1 is an ascending dose regimen, where the subject will get increasingly larger doses as the trial goes on, but multiple subject will still get that. Fgf10 (talk) 09:00, 9 September 2018 (UTC)

Traditionally, multiple doses are tested in Phase 1 clinical trials, but not usually for Phase 3 clinical trials for the reasons Fgf10 has elucidated. There are attempts to change this approach, through Adaptive clinical trials which do investigate dose modification while exploring the therapeutic effect. Klbrain (talk) 23:41, 9 September 2018 (UTC)

People who need 4 hours of sleep.

I'm 1 of those people who need 8 hours of sleep, so I've always been fascinated (and bummed out) about people who only need 4 hours of sleep. I've heard a lot of CEOs and such only need 4 hours of sleep. Now I finally understand how some people can work overtime jobs. Do we know what's the 50th percentile for sleep schedules? Do we know if there's disadvantages to needing more or less hours of sleep? I even wonder about lifespan. An also an evolution question: years ago I read an article that blue-eyes were a mutation, somewhere among White people thousands of years ago, mutated a blue eyed gene. Now I don't suspect we know much about sleep schedules for humans hundreds-thousands of years ago, but now I'm wondering maybe at 1 time, all the humans in the world needed the same hours of sleep, and someone somewhere evolved to differently. Is sleep schedules also genetic? Both my parents need 8 hours of sleep, and they are different races. Same with my sister. And I asked her before if her boyfriend "needs less hours of sleep than her" and she agrees. And then this makes me wonder, men needing less sleep than women is okay, but, what about the other way around, as a relationship question: can a man who needs 8 hours of sleep, be paired with a woman who only needs 4 hours of sleep? Does anyone know of any relationships which have failed because of this? Do we know what % of the population only need 4 hours of sleep, and I've also heard this is predominantly to men, so perhaps the standard deviation for sleep schedules in men is greater than in women. Oh, and should I lastly say, everyone once in a while, I still meet people who 'deny' people who only need 4 hours of sleep, but I don't think this is a dispute among scientists anymore. They're inclined to believe that they'll suffer in the long run. Thanks. 67.175.224.138 (talk) 10:56, 9 September 2018 (UTC).

I think you'll find that people who sleep only 4 hours also mostly take a siesta, or 'power nap' as they call it. Personally I think having a shorter sleep and a siesta is a better idea but unfortunately modern working hours don't normally go well with that. CEOs of course can do their own hours. Dmcq (talk) 11:30, 9 September 2018 (UTC)

One time Tim Russert was interviewing some old-time Yankees players. Phil Rizzuto commented that Joe DiMaggio (who was known for enjoying the night life) used to take a "power nap" in the dugout when the Yanks were at bat. ←Baseball Bugs ^{What's up, Doc?} carrots→ 11:47, 9 September 2018 (UTC)

I think one of the most important talents of any CEO is the ability to lie consistently, frequently, and convincingly in order to make himself look good. That's why your wages and pensions get cut to give them ever bigger bucks... Wnt (talk) 13:00, 9 September 2018 (UTC)

Individual need for sleep can indeed be trained to lesser hours. The Sleep cycle is even known to adapt to that. Id agree with Dmcq not trusting the image CEOs draw of themselves tho it is probably part of their job to look like a blueprint of a healthy workoholic. Most are likely Powernapping at work. While everyone thinks they work 14h/day they may actually sleep 4 hours. Why else do they all need a highly payed Secretary to guard their office door?!

But its a very different case in military. Military "Elite" units like Combat divers for example are actually trained to minimize their need for sleep down to 2 hours per day, on missions. Of course that only works for a few weeks at worst, but it works. --Kharon (talk) 22:03, 9 September 2018 (UTC)

Sleeping just 4 hours could explain the crazy behaviour of some CEOs. There's one who makes electric cars whose ill-advised tweeting has been in the news lately, for example. 173.228.123.166 (talk) 23:50, 9 September 2018 (UTC)

1% of the population need 4 hours or less sleep. A few examples:

• Stanley A. McChrystal: "McChrystal is reported to run 7 to 8 miles (11 to 13 km) daily, eat one meal per day, and sleep four hours a night."

• Narendra Modi

• Paul Erdős: "… he only needed three hours of sleep. He’d get up early and write letters, mathematical letters. He’d sleep downstairs. The first time he stayed, the clock was set wrong. It said 7:00, but it was really 4:30 A.M. He thought we should be up working, so he turned on the TV full blast. Later, when he knew me better, he’d come up at some early hour and tap on the bedroom door. ‘Ralph, do you exist?’ The pace was grueling. He’d want to work from 8:00 A.M. until 1:30 A.M. Sure we’d break for short meals but we’d write on napkins and talk math the whole time. He’d stay a week or two and you’d collapse at the end."

As for negative effects in lifespan, one has to take into account here that sleeping time should be subtracted from the lifespan to make a fair comparison. Suppose that sleeping 8 hours a day will lead to a 100 years lifespan. But you'll then have been awake for a mere 66.67 years. If you live more than 80 years with 4 hours of sleep a day, you'll have been awake for more than 66.67 years. Note that Paul Erdős died at age 83. Count Iblis (talk) 00:23, 10 September 2018 (UTC)

It should be noted that anecdotes are not the singular form of data, and that the existence of memorably exceptional individuals does not mean that most people do not suffer from getting less than a certain minimum amount of sleep. This study for example indicated that sleeping less than 6 hours per night leads to a 12% increase in dying before your anticipated lifespan. That people exist who seem to thrive with less sleep does not mean that humanity can thrive on less sleep. The existence of outliers does not represent sound lifestyle advice for the bulk of the population. Or simply put: don't trust what the weirdos can do; they're memorably weird for a reason. Put your trust in what almost everyone else should be doing. --Jayron32 01:33, 10 September 2018 (UTC)

Erdős was also an amphetamine user (mentioned in his wiki biography). 173.228.123.166 (talk) 04:33, 10 September 2018 (UTC)

I happen to thoroughly enjoy my living hours spent sleeping, and strenuously object to the notion that they ought to be subtracted from total time spent living for "fair comparison". 202.155.85.18 (talk) 07:15, 10 September 2018 (UTC)

Not particularly relevant to your main question, but recent genetic studies seem to indicate that European early modern humans (aka Cro Magnon Man) had dark (brown or "black") skin and blue eyes. Iapetus (talk) 09:29, 10 September 2018 (UTC)

If you want to see what happens when a person forces less and less sleep, read about Dick Vermeil's train wreck of a carreer with the Eagles. 216.59.42.36 (talk) 13:23, 11 September 2018 (UTC)

September 10

What's the explanation for "Larger diameter axons have a higher conduction velocity"?

I read on khanacademy site "Larger diameter axons have a higher conduction velocity, which means they are able to send signals faster. This is because there is less resistance facing the ion flow. We have a lot of ions flooding into the axon, so the more space they have to travel, the more likely they will be able to keep going in the right direction.". The reason that this site brings it isn't understandable to me, because according to my logic many times the smaller diameter the faster fluid velocity. I have two examples for my claim: 1. Hypertension of the blood circulation. 2. A simple water pipe, as the diameter is smaller the flow is stronger and faster. So this clame that "Larger diameter axons have a higher conduction velocity, which means they are able to send signals faster" isn't understandable to me. What's the correct explanation for that? 93.126.116.89 (talk) 01:57, 10 September 2018 (UTC)

I don't know anything about axons, but in your water pipe example, the larger diameter pipe transports far larger volumes of water per unit time than the smaller diameter pipe, assuming other parameters like head pressure are held constant. A sudden reduction in pipe diameter (i.e. a nozzle) may result in a sudden increase in the flow velocity, but over longer pipe lengths that effect is opposed by increased drag against the sides of the pipe (due to the square cube law) which reduces velocity. 202.155.85.18 (talk) 02:36, 10 September 2018 (UTC)

We explain part of this at Length constant, but there's a lovely presentation at [[7]] that goes further. The length constant is pretty easily understood as the amount of the current that goes down the neuron versus the amount that escapes; the other relevant concept (from the link) is that "Each time an ion channel needs to open to recharge the action potential, this delays the propagation of the action potential by ~1 ms." Hence the evolutionary tendency either to make bigger cables (decreasing r_i) or else to insulate them (increasing r_m). Wnt (talk) 03:07, 10 September 2018 (UTC)

Electricity = a flow of electrons

Would it be correct or accurate if I'll defined "electricity" as 'a flow of electrons'? (I know what the article here says, but I'm asking specifically about this definition). 93.126.116.89 (talk) 03:45, 10 September 2018 (UTC)

No it really doesn't work like that. 173.228.123.166 (talk) 04:29, 10 September 2018 (UTC)

A flow of protons can also be an electric current carrier. But if the electrons and protons flow together they cancel each other out! Graeme Bartlett (talk) 07:39, 10 September 2018 (UTC)

A flow of positrons can also be a current carrier, as can a flow of ionic species within a solution...but for a relatively lay understanding of electricity, it's fine to describe it as a flow of electrons as that describes almost all of the electrical phenomena familiar to the average punter. 202.155.85.18 (talk) 07:44, 10 September 2018 (UTC)

Inside an ordinary metal conductor it is correct to describe an Electric current as a flow of electrons. But Electricity (see article) embraces both this and many other phenomena involving Electric charge, and with magnetism constitutes the phenomenon of Electromagnetism. DroneB (talk) 11:23, 10 September 2018 (UTC)

• "A flow of charge" would be better. A flow of electrons is certainly electricity and it's the common one especially in metals, but so would be a flow of any charge carrier, including positive charges. Andy Dingley (talk) 11:42, 10 September 2018 (UTC)
• "Flow of electric charge" is really the best definition, there are all sorts of electricity that do not involve flow of electrons, besides the ones already notes, P-type semiconductors have electricity that flows in the form of positive charge "holes" in the semiconductor. Of course, the actual Wikipedia article on electricity would have answered the question for the OP sufficiently, so I'm not sure why he didn't look there. According to that article "Electricity is the set of physical phenomena associated with the presence and motion of electric charge." That seems like a perfectly fine definition. --Jayron32 12:01, 10 September 2018 (UTC)

Fire has to have heat, fuel and oxygen?

I understood from the article fire that fire needs three things in order to exist: heat, fuel and oxygen. I have gotten some questions on it: 1) Is it always necessary to have oxygen? (I'm asking it because I saw this video on Youtube that says: "to create fire you need 3 things: some fuel, and oxidizing agent normally oxygen, and enough heat to raise the fuel to what known as ignition point.". It seems from his things that there are other oxidizing things that can cause to it. What are the other oxidizing materials for example that can cause fire? 2) Does any electricity take place while having combustion? (in other words there is a relation between the light that we see in an incandescent light bulb that generated by electricity to a combustion of a wood for example?) I'm looking for a relationship between electricity to any kind of combustion. Can I claim that any burning involves electricity characters? When people in ancient times took two stones or woods and rubbed them in each other it caused to ignition as I understand due to electricity in those things. 93.126.116.89 (talk) 19:24, 10 September 2018 (UTC)

Consider, for example, the act of striking a match. The match will flare, but if there is no oxygen present it will not burn. 86.133.58.126 (talk) 19:28, 10 September 2018 (UTC)

We discussed the theory behind fire - and we specifically discussed whether matches can burn in anoxic environments - almost one year ago today. Nimur (talk) 01:39, 11 September 2018 (UTC)

So that's why this sounded so familiar... Yep. See my comments from last time. shoy (reactions) 18:33, 11 September 2018 (UTC)

Light bulbs used to have a filament in a vacuum. The light produced is not a burning fire, it's simply that the passage of electricity through the filament heats it up, causing it to glow. 86.133.58.126 (talk) 19:34, 10 September 2018 (UTC)

They still do. ←Baseball Bugs ^{What's up, Doc?} carrots→ 20:29, 10 September 2018 (UTC)

No, mostly they don't. --76.69.47.228 (talk) 03:01, 11 September 2018 (UTC)

Interesting. What percentage is "most"? ←Baseball Bugs ^{What's up, Doc?} carrots→ 03:06, 11 September 2018 (UTC)

Where I live, it's becoming difficult to find filament light bulbs. Supermarkets are hardly stocking them anymore. The country has moved strongly toward LED lamps. Akld guy (talk) 03:27, 11 September 2018 (UTC)

Assuming you mean ordinary household light bulbs, I don't believe this is much of the reason. I believe our article 76 linked to is correct, and incandescent bulbs of that sort were inert gas fill for a long time. (Halogen also started to become more common although there were always small light bulbs, inside a larger covering if designed as a replacement for ordinary A60/E26 bulbs.) What vacuum light bulbs still exist are specialist or very old ones. Our article mentions smaller lamps but AFAIK even torch light bulbs are usually inert gas. Xenon if they're fancy. I'm not sure about incandescent bulbs used in Christmas lights however. Nil Einne (talk) 10:01, 11 September 2018 (UTC)

"Fire" is not a scientifically rigorous defined concept. "Heat, fuel, and oxygen" is a good rule for most of the fires directly affecting humans - it's, IIRC, a rule that is taught to help people to avoid dangerous accidents with fire. But you can burn many things that burn in an oxygen atmosphere in a fluorine atmosphere (usually to much more spectacular effect) - it's just that fluorine atmospheres on earth are rare outside of laboratories. A famous combination for rocket fuels is Hydrazine plus nitric acid - what comes out the back of the rocket is certainly flames, but do you want to call this fire? --Stephan Schulz (talk) 20:54, 10 September 2018 (UTC)

Quoting myself from last year - "Flame, in the conventional sense, requires the three parts of the fire triangle..." In a "normal" fire, that would be your fuel (maybe some wood), and oxygen from the air, and ignition by a spark. In an abnormal fire, you might have a strange fuel - like amorphous boron or tungsten carbide; you might have a strange oxidizer - like nitrous oxide - and the heat of friction caused by boring a tungsten-carbide drill into a gas-pocket, resulting in an ignited BLEVE - a fiery hazardous material explosion. You can even get fire with no oxygen at all: instead of oxygen, you can burn with fluorine or chlorine - which is certainly not a safe thing to do at home!

As Stephan Schulz correctly points out, the term "fire", as we use it in day-to-day speech, is not really clearly defined. If we want a technically-accurate definition that meets our intuitive and normal use of the word, we might say that fire is any exothermic oxidation reaction that releases gases that are hot enough to incandesce.

From a practical perspective, we might defer to the definitions used by the experts: say, the National Fire Protection Association, a fire safety advocacy group in the United States. In their extremely thorough glossary of technical terms, they define "fire products": flame, heat, smoke, and gas; among the hundreds of definitions they provide for entities relating to fire, they also have some half-dozen definitions specifically for the word "fire," with excellent citations for each. For example, in one case, they define: "a rapid oxidation process, which is a chemical reaction resulting in the evolution of light and heat in varying intensities." In another usage, they define: "any instance of destructive and uncontrolled burning, including explosions."

The specialist - whether they're a fire-fighter or a physicist - might use the word "fire" with many different meanings in different contexts. The relationship between flame and electricity is also quite complicated: electricity can cause certain types of fire, and can be caused by certain types of fire (in the form of gases that get ionized by the heat of the flame). In the most common cases that apply to the study of fire, we would consider electricity to be a source of heat and/or spark for an otherwise conventional chemical flame - so you'd still need fuel (like a wooden material) and oxidizer (like air in the room). Here's one of the frightening famous Christmas Tree Fire Safety video from NFPA. Electric wires that are frayed or overheating can cause a huge conflagration in a real hurry, "with flashover occurring in less than one minute." When you reach flashover, your fire is so exothermic that it no longer spreads chemically, but actually ignites distant objects entirely via the emission of infrared radiation. Most humans don't really have a great appreciation of this fact - a fire that's about three inches in radius is controllable and extinguishable, but once it gets a little bit bigger than that - the physics gets weird, and the practical consequences get really bad.

Nimur (talk) 01:57, 11 September 2018 (UTC)

• [is there] a relation between the light that we see in an incandescent light bulb that generated by electricity to a combustion of a wood for example? As explained above, light bulbs work by the path electricity -> heat (see Joule effect) -> radiation (see Blackbody radiation). For fires, it depends; there is an appreciable amount of blackbody radiation from soot particles etc., but in many cases it is due to intermediary reaction species undergoing chemiluminescence (that is why you can see blue flames in Bunsen burners, even though the flame temperature there is lower than 2000K yet blackbody radiation is blue for about 6500-7000K).

I also questionthe assumption that flintstone fires involve electricity. According to Flint#To ignite fire or gunpowder, which unfortunately has poor sourcing on that point (the only ref is [8] which I would not imagine to be very accurate scientifically), "sparks" are created by exposing reactive iron or iron sulfide to the atmosphere; we are talking about this spark, not that spark. Tigraan^{Click here to contact me} 08:27, 11 September 2018 (UTC)

A well-designed fuel-burning lamp from the Victorian age onwards is brighter and whiter than black-body radiation, but this doesn't usually involve chemiluminescence, it uses a gas mantle and candoluminescence. This is a device for holding tiny quantities of rare-earth elements so that they can be heated by the flame. They then (like chemiluminescence) produce colours of light which are bluer than the black-body colours, but they do it by physics and spectroscopy (and aren't consumed) rather than by a chemical reaction. Andy Dingley (talk) 09:49, 11 September 2018 (UTC)

• There is a difference between oxidation (in the chemical sense) and fire. You can also have fires which don't involve any oxygen. But we live on a planet with a lot of free oxygen in the atmosphere, so that's by far the most common oxidiser, and so we tend to assume that it's the only one.

Look at some of the chemistry for liquid propellant rockets. These use a rapid combustion (i.e. a fire, and an oxidation) to release energy as mechanical thrust. They have to bring their own oxidisers with them, just because they need so much of it and it would be difficult to supply enough of it by scooping it from the atmosphere, not just because that also allows them to operate in a vacuum and so reach space. Many different sets of chemistry have been used to make rocket fuels, and there are several used for the oxidiser too. See liquid rocket propellant or read Ignition!. ISBN 0813599199. (neither of these wiki articles are very good, but Ignition! is excellent and newly reprinted). A popular oxidiser is liquid oxygen, because it's relatively cheap and safe and it works well. Unfortunately it has to be kept very cold to liquefy it, so it can't be stored in the rocket. So the military use nitric acid, or nitrogen tetroxide instead. There are also exotic chemicals like chlorine or fluorine compounds - these will certainly give "a fire" just like oxygen, if you did an experiment in an atmosphere rich in them. Andy Dingley (talk) 09:43, 11 September 2018 (UTC)

As far as a connection between the chemical reactions that we call "fire" and electricity, the two halves of the reaction mixture can be segregated such that in order for the oxidation reaction to proceed, electrons must cross through a conductive material. This allows us to extract work in the form of electrical energy. Such an arrangement is known as a fuel cell, the most common of which is based on the reaction of hydrogen combustion, but they can also be designed around the combustion of the regular hydrocarbons we more commonly use as fuels. What this illustrates is that there is an electrical interaction taking place in all combustion reactions (and, in fact in all chemical reactions) involving changes in the electronic structures of the atoms, ions and molecules in question, but without particular contrived situations being deliberately created to take advantage of the electron flows, the relationship to electricity is trivial. 139.194.67.236 (talk) 10:22, 11 September 2018 (UTC)

What parameters do you need to describe an audible sound?

Frequency and amplitude of the wave, duration, intensity? Is that all? --Doroletho (talk) 21:04, 10 September 2018 (UTC)

Wikipedia has some good information at Sound pressure and Decibel#Uses. Dolphin (t) 21:46, 10 September 2018 (UTC)

Depends what you mean by "sound". Describing or synthesizing the sound of a musical instrument would take many more parameters (in the old days you'd define a sound envelope by attack, sustain, release, and decay, at different frequencies and amplitudes. Most sounds would have a complex timbre or mixture of frequencies and still be perceived as one sound. - - Nunh-huh 22:22, 10 September 2018 (UTC)

Basically, I had human speech in mind. But I imagine music is also complex and well-researched, and there must be good references about this. --Doroletho (talk) 23:59, 10 September 2018 (UTC)

Free books! Julius Smith, a professor at the Stanford Center for Computer Research in Music and Acoustics, has made all of his textbooks available at no cost. He's a world expert on the practical mathematics to represent music and sound.

The starting point for a representation of a sound is a full waveform recording, which may be digitized; and from there, it takes a lot of math and science to compress the sound in a manner which is perceptually similar to the original waveform using as few parameters as possible. A good audio compression scheme can achieve thousand-to-one compression, or better, in ideal circumstances - in other words, you can describe a sound using just a few parameters. The more parameters you use, the more accurately you can re-create the original sound with minimum distortion; phrased another way, the more parameters you use, the more different types of sounds you can accurately and uniquely describe.

Nimur (talk) 04:40, 11 September 2018 (UTC)

...Regarding human speech: here's a link right to the chapter on the Vocoder, a review of one historically-important effort to parameterize human speech at Bell Labs. These books are great - they're thorough but simple enough to understand, and Julius cites more references cited than you'll probably read. Nimur (talk) 13:52, 11 September 2018 (UTC)

• Properties of sound are often simplified to concepts like sound intensity (amplitude), pitch (fundamental frequency), and Timbre (related to waveform shapes). There are also psychological effects of sound, which include things like loudness. --Jayron32 13:57, 11 September 2018 (UTC)

September 11

Planets with natural satellites with natural satellites?

Are there any planets (or so-called "dwarf" planets) that have natural satellites with natural satellites? As far as I know, there aren't any. But I've never heard anyone definitively say that there are none that we know of. A Quest For Knowledge (talk) 01:10, 11 September 2018 (UTC)

see http://curious.astro.cornell.edu/about-us/44-our-solar-system/the-moon/general-questions/104-can-moons-have-moons-intermediate Graeme Bartlett (talk) 01:19, 11 September 2018 (UTC)

We don't know of any. Most moons around planets have Hill spheres too small to support significant satellites, and our Moon has the added problem of mascons making many lunar orbits unstable. However there may have been some in the past. Rhea (a moon of Saturn) has been speculated to have rings, and the equatorial bulge on Iapetus may have been formed by a de-orbiting subsatellite. (While Iapetus has a significant Hill sphere, more than any other moon because of its size combined with its distance from its parent planet, it was tidally locked to Saturn, and therefore ended up rotating slowly enough that its subsatellite would have suffered significant tidal deceleration. This process could have happened on some other moons, but only on Iapetus and perhaps Oberon would the process take long enough that the equatorial ridge wouldn't have been obscured by later impacts.) Double sharp (talk) 01:32, 11 September 2018 (UTC)

We don't find such systems in our own solar system, and we probably won't find them elsewhere, because they are unstable ...for reasonable and realistic mass and distance parameters. In astronomy we have a special appreciation for the statistical likelihood of observing an astronomically-unlikely event amidst an astronomically large sample-size; but at this time, our best observational methods still do not allow us to see such detail as a planet's satellite except for those planets that are inside our own solar-system. Even our own solar system is sparsely explored, and we have very limited observations of our outer planets. So, it's unlikely we'll see such a moon-with-satellite within, say, the next few generations of human lifetimes.

A standard homework problem for students of astrophysics is to calculate the number of orbits (years) until an n-body system - such as a sun/planet/moon/satellite system - becomes unstable. Here's an example from Cornell University's Astro 3303 class. The hard part is making sure your numerical method isn't more unstable than the physical system! The standard method is unfortunately not suitable - it is this homework-problem that tragically results in the loss of mathematical naïveté for many an up-and-coming computational physicist. Nimur (talk) 04:52, 11 September 2018 (UTC)

It may be thinkable on an Polar orbit where the "moon-moon" would keep an equal distance to the moon and the planet, but it would remain a delicate balance act to stay there for billions of years. Even more close to impossible wonder would be the history how it got there, but then, our earth is a real wonder too with all the different, needed ideal conditions to support life, met on a single planet. --Kharon (talk) 05:04, 12 September 2018 (UTC)

Not only would it need to be in a polar orbit, but it would need to be in a planet-synchronous orbit (analogous to a sun-synchronous orbit) in order to maintain a constant distance from the planet's surface. To maintain stability of this orbit the tendencies for the orbital parameters to evolve would need to cancel one another. Over the periods of time relevant to the evolution of the solar system such an orbit would be vanishingly unlikely to remain stable. Changes in the moon's equatorial bulge or radiation pressure due to solar output changes could be significant enough to gradually lead to destabilization and a reduction in orbital inclination. 114.124.144.185 (talk) 06:27, 12 September 2018 (UTC)

Polar orbits would tend to be unstable to the Lidov–Kozai mechanism, in which inclination is traded for eccentricity. Double sharp (talk) 06:30, 12 September 2018 (UTC)

Nereid may be a binary satellite of Neptune according to this paper. 114.124.144.185 (talk) 05:50, 12 September 2018 (UTC)

Your link is to the mythological entity, the relevant article is Nereid (moon). {The poster formerly known as 87.81.230.195} 2.122.60.253 (talk) —Preceding undated comment added 17:15, 12 September 2018 (UTC)

That paper is very old, though: it's pre-Voyager. So this may have been refuted by newer data. Double sharp (talk) 08:12, 12 September 2018 (UTC)

Default human template

I have heard that the "default" human template is female, and in the (perhaps artificial) absence of testosterone during development a female body type will result, irrespective of even the sex-determining chromosomes.

However, is this status of "default" of any medical significance?--Leon (talk) 10:38, 11 September 2018 (UTC)

This "default" is due to the XY sex determination system used in mammals. The Y chromosome has relatively few active genes, mostly serving as a signal to activate the male pattern rather than the female. There are many more genes on the X chromosome. The different sizes (and, thus, different genetic contents) means that any gene form (allele) present on the X chromosome will be expressed, regardless of questions of dominant or recessive alleles. This makes certain genetic disorders (red-green colorblindness, hemophilia, etc) more common in males than females. --Khajidha (talk) 13:41, 11 September 2018 (UTC)

To elaborate for pedagogical value, only around half of humans have a Y chromosome, so obviously it can't contain any genes necessary for non-biological males. Conversely, the X chromosome behaves more or less like any other chromosome; most of its genes have nothing to do with biological sex or reproduction, since, as noted, there is no "trigger" to make a human fetus develop as female. The sex chromosomes evolved from a regular pair of autosomes; since only males inherit a Y chromosome, this means there's a massive evolutionary pressure to delete genes from said chromosome, which is what has caused it to become so small. In some mammals it consists of only the single TDF/SRY gene, which is the gene that triggers male development. --47.146.63.87 (talk) 19:28, 11 September 2018 (UTC)

I don't follow the evolutionary pressure bit. Why is there this evolutionary pressure?--Leon (talk) 19:35, 11 September 2018 (UTC)

Y chromosome § Origins and evolution: any alleles on the Y chromosome have a ~50% chance of hitting a dead end: if the possessor of the chromosome has only female offspring, the chromosome dies with them. This is why there's a single Y chromosomal Adam we can trace: the Y chromosome alleles from all other human males living at the same time have died out. Additionally, if a Y chromosome allele were essential for all members of the species—not just males—it would be lethal for any female offspring of the man carrying that allele, since they wouldn't have it. So, any genes that were on the X/Y chromosome's ancestral autosomes that are beneficial to the female phenotype tend to get removed from the Y, leaving only the copy on the X, which is inherited by both sexes. --47.146.63.87 (talk) 21:56, 11 September 2018 (UTC)

Yes, many if not most intersex conditions are the consequence of the interplay between components of the sex-determination system. For example, in androgen insensitivity syndrome, a fetus with one or more Y chromosomes will nevertheless develop a female phenotype, often with infertility. In this condition, the Y chromosome is present and functioning, but androgen receptors are defective, meaning they don't respond normally to testosterone. The gonads are triggered by TDF to begin developing as testes and secreting testosterone, but androgen receptors don't respond to it, so to varying degrees the body continues to develop along the "default" female pathway. --47.146.63.87 (talk) 19:28, 11 September 2018 (UTC)

All very interesting. Thank you!

A follow up question: I've just read something on X-inactivation, and noted the tortoiseshell cat as a typical example of how the differences between the two X chromosomes that females have can have an interesting effect. Is there anything as visually obvious as this that happens in humans?--Leon (talk) 21:10, 12 September 2018 (UTC)

Is there a material that it's 100% non electrical conductive?

We used to say that wood or other materials such as plastic are not conductive for electricity, but based on what I understand everything is conductive but some of the materials are low conductive while others are highly conductive, and all materials have a measurement on a scale of the conductivity. Is it correct? Is there no an exception for material that is 100% non conductive? 93.126.116.89 (talk) 15:18, 11 September 2018 (UTC)

Some sort of Superinsulator? DMacks (talk) 15:22, 11 September 2018 (UTC)

How much theoretical physics do you want to use in evaluating your answer? Even if no electrons flow, an electric current may still occur: the displacement current. This is not even one of those weird quantum-mechanical, "only-there-in-the-statistical-sense" concepts! Displacement current is a real phenomenon and is a key component of classical electrodynamics. So even if you had a material that were somehow completely able to block the flow of charged particles, you still could not preclude the accumulation of electric charge outside of the boundaries of that material - in other words, even if you had a perfect insulator, electric current would still flow, and the stuff surrounding the insulator material would function as a capacitor. In yet other words, even if you magically prevent matter (electrons and ions) from moving, by building a super perfect insulation material, it is a law of nature that the photons will still get through and carry your very real, very physical electric current without the motion of any electron or other charged particles - we might say this is spooky action at a distance (although it travels only at a finite speed) - and we'd be in good company - that was the title of Chapter 23 in one of the most important physics books ever written!

This ingenius insight is attributed to James Clerk Maxwell, who corrected the faulty Ampère's law by generalizing it into a more correct conservation law - and it is this very same generalization from whence all of general relativity ultimately derives. It is no coincidence that this equation is the one which defines the speed of light, whether you consider its speed inside a material or through a totally empty vacuum.

One must work one's way up in this world: here's a few good books to get you started:

• Physics for Scientists and Engineers (Mosca & Tipler)
• Introduction to Electrodynamics (Griffiths)
• Classical Electrodynamics (Jackson)

...so you start with the advanced science-and-engineering stuff, and spend several years working your way up to the introductory material, and finally you read the really easy "classical" stuff. If you don't like those books, we also have a thorough list of textbooks in electromagnetism.

Nimur (talk) 16:31, 11 September 2018 (UTC)

• Over what distance? It's a (surprising) aspect that something isn't a perfect insulator immediately, but the current falls off exponentially with depth. So something that you think of as an insulator (or in a related case, something that's opaque to light) will still transmit or conduct it, if it's in a sufficiently thin layer. Andy Dingley (talk) 16:59, 11 September 2018 (UTC)

• That's technically correct that nothing is perfectly insulating, but it depends where you put the cutoff. Except in vacuum or maybe in a material at absolute zero, there is pretty much never zero free charge carriers, so any simple model (e.g. the Drude model) will tell you charges move (i.e. there is current) if there is an electric field. However, if you look at Electrical_resistivity_and_conductivity#Resistivity_and_conductivity_of_various_materials, you can see that the conductivity of metals is always above 10^6 S/m while that of common insulating materials is below 10^-6 (or 10^-4 if damp wood counts). The ratio between the two limits (worst conductor vs. worst insulator) is gigantic (10^10 to 10^12) - to put that in perspective, that is the same ratio as the height of Mount Everest to the width of a hair. If you were evaluating non-smoothness of Earth's surface, you would surely assume that lengths below the millimeter are outside your cutoff - you consider those as flat even if they are technically not perfectly flat. (This answer does not talk about semiconductors because my knowledge of those boils down to "here be quantum").)

You might also be interested in our article about electrical breakdown (whose most common manifestation is thunder inside "insulating" air). Tigraan^{Click here to contact me} 17:17, 11 September 2018 (UTC)

Gravity

What's the diff tween a gravity wave and a graviton? — Preceding unsigned comment added by 80.2.22.73 (talk) 23:35, 11 September 2018 (UTC)

A Graviton is a purely hypothetical part(icle) that some scientists believe exists. A gravity wave is actually more correctly a Time dilation-wave (also measured/noticed that way) that the mainstream of physical science decided to call "gravity wave", probalby because they assume such waves are caused when 2 black holes unite into one. --Kharon (talk) 04:09, 12 September 2018 (UTC)

A gravity wave is a wave in a fluid where the restoring force is gravity. This is the kind of wave that you see when wind blows on the ocean; if you're a meteorology nerd, this is also the kind of wave that causes certain high cloud formations. Here's a cool image of one from the NOAA Cool Image website at the Storm Prediction Center. Here's some more imagery from the MODIS satellite: Gravity Waves, from NASA Goddard. Oh, and here's a special issue of the peer-reviewed journal Atmosphere: Atmospheric Gravity Waves, the March 2017 issue, with just boatloads of science in it.

A gravitational wave is a relativistic phenomenon that has been theorized for a long time and only recently measured. These are very low-amplitude, self-propagating changes in the shape of the universe that occur when very very dense massive objects move. Ever since the theoretical math we call relativistic gravity was first studied - about a hundred years ago - we knew this should happen - but it was only 2016 when we first had instrumentation sensitive enough to measure this very tiny effect. For this achievement, and a lifetime of scientific contributions, the 2017 Nobel Prize in Physics was awarded to three scientists. Here is a video by some guy named Rainer Weiss hosted on Youtube, in which he just drones on and on about gravitational waves for like three quarters of an hour. If you can handle it, you'll glean little bits of wisdom: for example, gravitational waves don't just come from black holes - this other guy named Albert does a calculation for a tiny gravitational wave coming out of a passing train, but he said it was way too small to notice - praktisch verschwindenden.

A graviton is a mathematical description of the propagation of gravity as a localized, quantized amount of change. The math for this description does not work out very easily - so most scientists do not use this mathematical formulation. It is studied by certain communities of theoretical physicists. For a reputable source, here's a little bit of discussion about quantization limits on the LIGO - but there's more to worry about quantization noise, shot noise, photons, and phonons - these are far more practical concerns than any quantization limits of the gravitational wave itself. In fact, there's more gravitational noise from seismic vibrations - not because of the vibrations themselves (which are low frequency and can be easily measured and compensated), but because the compression waves cause mass density changes in the soil which then affect the conventional Newtonian gravity measured by the detector! The point is: no real scientist is measuring gravitational quantization; even if it did exist, it's way below the regime of what we can measure with today's experimental physics.

(It's almost as though we, mere denizens of the Wikipedia Reference Desk, can actually find free publications authored by professional experts who know about this stuff!)

Nimur (talk) 04:50, 12 September 2018 (UTC)

One central issue with all that is often overlooked tho. Its still unknown how gravity exactly works, as Nimur also circumscribe in his description of this graviton that may actually not exist in reality. Till now all science around gravity is actually better tagged as "phenomenology" than science. --Kharon (talk) 06:20, 12 September 2018 (UTC)

I'm sorry,... is it simply your own esoteric view that "all science around gravity" is not actually science, or can you cite a reference for that statement?

The Reference Desk is not a place to spout your own original pseudoscientific research. If you are not qualified to help respond to questions by finding encyclopedic-quality resources, you should not contribute answers to queries here.

Nimur (talk) 14:20, 12 September 2018 (UTC)

I think I see Kharon's point (and presume he's including phenomenology as science). However I'd also say that he was out of date. It's a fair description of the period from Newton to Einstein, but was invalidated by GR. Andy Dingley (talk) 15:13, 12 September 2018 (UTC)

GR describes the phenomenon of gravity but we don't have a theory of how it works (quantum gravity) the way we have a theory of electrodynamics. There's a ~ 10 minute youtube interview with Freeman Dyson[9] where he says there might be no gravitons or quantum gravity, and that gravity might instead be more like a temperature, a statistical property of bulk matter. I watched that recently and have actually been meaning to ask about the idea here. I see now that he also has a longer talk[10] so I guess I'll watch it when I get a chance. 173.228.123.166 (talk) 16:00, 12 September 2018 (UTC)

So you're broadly agreeing with my comments on Kharon's post, but seeing the "Till now" as much closer? I can go with that. Although even then, you're arguing 50-ish years vs. 100. Even post-GR theories have been around for some time now. Andy Dingley (talk) 19:36, 12 September 2018 (UTC)

Yes basically, afaict the "till now" extends to the present. GR is considered an unphysical theory because it's not quantized. And there are a bunch of approaches like superstrings that have too many loose ends to be considered theories the way QED is a theory. So at present, we do not have a physical theory of gravity. This is cool and hip, but it's still "out there". I don't understand much beyond the popular level, but the quantum gravity article describes some of the unresolved issues. 173.228.123.166 (talk) 21:05, 12 September 2018 (UTC)

September 12

Jellyfish

Can you assume that there are no jellyfish in the sea after the summer months (I Mean now and in the next month). Is that something restricted to the summer? I have south Spain in mind, other places on the Mediterranean might be interesting. — Preceding unsigned comment added by 37.252.180.169 (talk) 03:24, 12 September 2018 (UTC)

There is a Spain Travel forum post on that subject; you might try a query there: "Jellyfish summer 2018 - Spain Forum". www.tripadvisor.com. TripAdvisor. June 26, 2018. —107.15.157.44 (talk) 05:57, 12 September 2018 (UTC) ... Reports that I could find regarding beach closures in Spain due to jellyfish are dated April & May (2018).

I have found some random comments in travel sites too besides anecdotal evidence provided by locals. But I was wondering from a more scientific point of view. Does winter decimate jellyfish populations? 31.177.99.137 (talk) 13:16, 12 September 2018 (UTC)

If there were no jellyfish in the sea at all, where would the next generation of them come from? ←Baseball Bugs ^{What's up, Doc?} carrots→ 10:57, 12 September 2018 (UTC)

I obviously mean on the sea shore. But even then, it might be possible that there's no specimen of some living being in winter, only eggs that will hatch in the next season. 31.177.99.137 (talk) 13:16, 12 September 2018 (UTC)

Thanks for clarifying. If it was obvious, I wouldn't have asked. :) ←Baseball Bugs ^{What's up, Doc?} carrots→ 13:21, 12 September 2018 (UTC)

In a sense, the next generation of jellyfish will come from polyps ! What we usually think of as a jellyfish is actually a jellyfish medusa - the final sexually reproducing phase in a complex life cycle. Medusae have relatively short lives compared to the polyps that bud them. Gandalf61 (talk) 13:24, 12 September 2018 (UTC)

"Patterns of jellyfish abundance in the North Atlantic" discusses reasons for seasonal variation of jellyfish in the North Atlantic. It looks as if in the open ocean, jellyfish populations peak with prey populations, whereas nearer shore (in the continental shelf area) they peak with surface temperature. (The paper also states that in the shelf area "advection and aggregation" affect jellyfish population, and this appears to be advection and aggregation of prey, which leaves me puzzled.)--Wikimedes (talk) 07:16, 13 September 2018 (UTC)

Advances in consumer facing industries

Why is it that consumer facing industries such as automotive, retail, personal banking etc seem to advance faster than corporate industries such as legal, investment banking, construction etc especially in terms of IT and digital? Clover345 (talk) 06:33, 12 September 2018 (UTC)

Buisiness and government will want to enter into long term contracts, perhaps using tenders. They also want stability and assurance in their IT systems, so they don't just want to take whatever is the latest that will mean they needs to change instructions and cope with a new bunch of issues. Operating system changes for example mean that applications that use them have to be changed, and then retested. There is a lot of expense in changing unnecessarily. Some industries are very conservative and may be regulated to avoid changes. This includes aviation. Graeme Bartlett (talk) 09:49, 12 September 2018 (UTC)

I'd say manufacturers strive to make consumer products that look shiny but fall apart in a couple of year. Industrial equipment, on the other hand, is made to last, often some decades, and it normally does not matter how it looks. --31.177.99.137 (talk) 13:24, 12 September 2018 (UTC)

Planned obsolescence is the tradeoff for products being relative inexpensive. If you want an industrial-strength laptop PC, for example, you're going to pay a lot more than what you would get at Best Buy. Related to Project management triangle. ←Baseball Bugs ^{What's up, Doc?} carrots→ 15:22, 12 September 2018 (UTC)

Quantum CAP Theorem

What are the limits on syncing up distributed Quantum machine learning?

I.e. has anybody done the math on a quantum version of the CAP theorem?

In short, given a swarm of killer robots, how do you ensure that they all learn together?

Hcobb (talk) 14:08, 12 September 2018 (UTC)

Fluid dynamics question.

If you have water flowing down a vertical steel pipe, and both the water and pipe were at 25 C. Now, if both the water and pipe were at 50 C, water would flow faster, because of this thing called friction. Change in viscosity with temperature. So my question is, which would flow faster, if the water were at 25 C and pipe at 50 C, or water at 50 C and pipe at 25 C. As far as I know, there is no difference with water flowing in a horizontal pipe, only vertical pipe. Thanks. 12.239.13.143 (talk) 18:17, 12 September 2018 (UTC).

If we can assume laminar flow i.e. no cross-currents perpendicular to the direction of flow, nor eddies or swirls, and that the fluid is incompressible and Newtonian, the empirical Hagen–Poiseuille equation will be useful, see Hagen–Poiseuille equation#Equation. It requires knowledge of the liquid's dynamic viscosity μ which is a function of temperature shown at Viscosity#Dynamic-viscosity. See the theoretical development of laminar Pipe flow at Hagen–Poiseuille_equation#Derivation and Hagen–Poiseuille flow from the Navier–Stokes equations. DroneB (talk) 20:53, 12 September 2018 (UTC)

I don't see how this is useful, my question was about temperature and not pressure. And I am not comparing different materials with same liquids, or different liquids with same pipe materials. Only same liquid and same piping material. Either way, I think the answer I was looking for is: cooler pipe cooling the hotter water, or cooler water cooling the hotter pipe - whichever is slower. And whichever answer that is, what are materials where the opposite is true, for different piping materials. 12.239.13.143 (talk) 22:56, 12 September 2018 (UTC).

While DroneB did miss the point of your question, I do not see what their answer has to do with pressure. (I also strongly doubt Hagen-Poiseuille applies for reasonable values of pipe diameter and flow speed for water.) The answer does make a decent job of explaining why temperature impacts viscosity (which impacts friction) but your original post seems to acknowledge that.

Friction is driven by the (viscous) boundary layer in the liquid near the surface, so what matters is the water's temperature. Now, of course, thermal transfer between pipe and water means that "the water's temperature" can hardly be fixed different from the pipe's (even if you try, water temperature near the pipe will likely not be at the regulation temperature), and that thermal properties of the pipe will eventually matter; but good luck on quantifying such an effect. Tigraan^{Click here to contact me} 11:28, 13 September 2018 (UTC)

This would be a pretty gnarly set of differential equations, one for heat transfer and one for flow, doable but tedious. In an ideal world where everything stays at a constant fixed temperature, you could set up a numerical solution with a computer program. In the real world, I suspect that the pipe and water would quickly come to temperature equilibrium, especially if the pipe is metal. shoy (reactions) 13:27, 13 September 2018 (UTC)

In order for the question to be "interesting but solveable" I would assume that the pipe is long and has large diameter...that means we have pretty good equilibrium of the pipe temp with the outer layer of water and a gradient towards the center that is at the supply temperature. That gets away from a pipe that is thin enough for temperature to equilibrate all the way to the center (making the question pointless). DMacks (talk) 15:26, 14 September 2018 (UTC)

Desire to raise legs

I am familiar with restless legs syndrome, albeit only from descriptions, and am almost certain that I am not talking about it!

Is there a name for the seemingly inexplicable desire to raise one's legs? Specifically, to a higher level than one's torso when lying down.--Leon (talk) 21:12, 12 September 2018 (UTC)

That's a new one, unless you're elevating them for circulation reasons. What have you found on Google so far? ←Baseball Bugs ^{What's up, Doc?} carrots→ 22:31, 12 September 2018 (UTC)

You might mention that to your doctor. If you also feel faint when you stand up, that is orthostatic hypotension and could be related. I've seen it claimed that sleeping with your head elevated is good for many reasons, so instinctually doing the opposite sounds slightly amiss. ObIncantation: we can't give medical advice here bla bla. 173.228.123.166 (talk) 06:50, 13 September 2018 (UTC)

Leon is not looking for medical advice, he is not even saying that he has a medical complaint. I wonder why anyone would suggest he see a doctor or suggest that the condition he asks about is "slightly amiss". I have been in nursing most of my life and have never encountered the idea that sleeping with your head elevated is good - although it is customary. Richard Avery (talk) 13:06, 13 September 2018 (UTC)

The OP should speak for himself. ←Baseball Bugs ^{What's up, Doc?} carrots→ 13:10, 13 September 2018 (UTC)

I'll speak for myself - I corroborate with Richard. I'm just curious. I'll add that this desire seems to be coupled with a general desire to get into strange bodily positions, but what I have already described is the most obvious manifestation of this.--Leon (talk) 16:17, 13 September 2018 (UTC)

Where have you seen this? ←Baseball Bugs ^{What's up, Doc?} carrots→ 18:13, 13 September 2018 (UTC)

If not circulatory maybe it's psychological, from some kind of anxiety? Regarding thing about sleeping with head elevated, here's an example:[11]. Obviously not RS but it's an example of some of the (possibly bad) info that's out there. Actually a quick web search shows the author is a "medical anthropologist" who writes lots more such unorthodox stuff. So skepticism is warranted. 173.228.123.166 (talk) 17:01, 13 September 2018 (UTC)

September 14

Defibrillator units

I was watching an early episode of Law & Order (season 2, episode 5 "God Bless the Child") in which hospital staff use a defibrillator in an attempt to resuscitate a small child. The doctor holding the paddles instructs a nurse to set the device to "18 watts per second". Now I'm no brilliant physicist, but if I remember rightly, watts are already joules per second. That would make this unit joules per second per second which would be rate of change of power. I googled around and there are other sources that refer to watts per second as the unit for defibrillation such as this one (which seems to get the relationship between joules and watts wrt time backwards). Some other sources quote doses in watt seconds, which would make more sense, as that reduces to joules but the terminology makes it clear to the operator that the machine is delivering a power for a time period. Does anyone know how the units of defibrillators are normally used in a typical hospital setting? 114.124.175.125 (talk) 00:49, 14 September 2018 (UTC)

Here is a great review article from the American Heart Association: Defibrillation - 2010 International Consensus on Cardiopulmonary Resuscitation and Emergency Cardiovascular Care Science With Treatment Recommendations. It's part of a whole series of scientific review, published in the October 2010 issue of Circulation (Vol. 122, No. 16), in which a panel of experts detailed the scientific studies and made recommendations for clinical use.

In scientific literature, defibrillation is characterized using several parameters: among them are the paddle type and placement; the total energy; the waveform of the shock; the number of shocks; and the energy level per shock, measured in Joules.

In a clinical setting - like a hospital - scientific accuracy might be sacrificed during common use. If the machine is an AED - an Automated external defibrillator - the operator might have limited or zero medical and scientific training. Though in many places, use of an AED is restricted to only those emergency responders who have certain levels of professional qualification - in other places, the recommended procedure is for the first person near the victim - trained or otherwise - to use the machine. So you can see how the operator might mess up some of the details of the physics.

"Watts per second" is a nonsensical physical unit, at least in the context of measuring an electrical shock during a medical defibrillation procedure. Even if we're generous and we assume the fictional character misspoke, and meant to say "eighteen watts-times-seconds," that's equal to eighteen joules, and it's not a meaningful or reasonable quantity of energy for a defib. Defib shocks are normally in the range of 100 to 300 joules. The duration of time that this energy is delivered is very short - different machines use different waveforms, but all the energy is usually delivered in the first 15 or 20 milliseconds. Normally this would be characterized by describing the energy (in Joules) and the waveform (by naming it, out of a small set of common waveforms like "Pulsed Biphasic Waveform" or "Biphasic Truncated Exponential Waveform"). If the user were a physicist and felt like wasting time during the emergency, they might convert to using watts as the unit of measurement, and compute somewhere between 1 and 2 kilowatts during the application of the shock.

As always, the easy way out is to forgive a little poetic license in a work of fiction - they shouted some technobabble for dramatic effect, and the show's writers probably spent less time researching the topic than I did just now. But hey, in addition to being a volunteer science-enthusiast, I'm also a volunteer emergency-responder and I like to know a little bit of theory in case it ever saves a few seconds during an emergency.

You can sign up to learn more about AEDs; a great resource that's probably available in your community is the Red Cross AED training class - they'll probably encourage you to get a CPR refresher too. "The average response time for first responders once 911 is called is 8-12 minutes. For each minute defibrillation is delayed, the chance of survival reduces by approximately 10%." Or, as I like to phrase it: the professionals are, by definition, the second responders to your emergency: you are the first responder - so why not take some time to prepare for it now?

Nimur (talk) 05:00, 14 September 2018 (UTC)

I second what Nimur said about the value of getting even minimal training. AEDs are widely deployed in public places now and stupid-easy to use. Some are just "slap the pads on two places on the chest--there is a pictograph on the pads themselves and it doesn't matter which goes where; press the big button and then follow the instructions that the device's voice tells you" (things like "call 911; hands off; shock delivered" and a metronome for chest compressions). And hands-only CPR is pretty simple too (plus a great soundtrack!). Some key AHA data are that the survival rate for cardiac arrest that occurs outside of a hospital setting in communities where AEDs are available and people have AED/CPR training is nearly 40%, vs <10% overall. Part of the basis for improvement is that 23% of those patients initially have shockable rhythms. DMacks (talk) 15:16, 14 September 2018 (UTC)

Did Prohibition Reduce Drinking?

Our article on Repeal of Prohibition in the United States says that:

• Alcohol consumption declined dramatically during Prohibition.
• Violent crime did not increase dramatically during Prohibition.
• Organized crime did not increase during prohibition.

There are indeed some sources that support at least some of those claims,[12][13] but a `quick web search also finds:

• The Effect of Alcohol Prohibition on Alcohol Consumption
• Did Prohibition Reduce Drinking?
• The Effect of Prohibition on Alcohol Consumption: Evidence from Drunkenness Arrests
• Did Alcohol Use Decrease During Alcohol Prohibition?
• How Prohibition backfired and gave America an era of gangsters and speakeasies
• Alcohol and Crime: The Prohibition Experiment
• Organized Crime and Prohibition: What Difference Does Legalization Make?
• Prohibition and the Rise of the American Gangster
• Prohibition Profits Transformed the Mob

So which view is supported by the sources? Or could it be, as one source says, "In truth, nobody really knows exactly how much alcohol consumption increased or decreased during Prohibition. The reason was simple enough -- people like Al Capone didn't pay taxes on their product and thereby report their production to the government. Licensed saloons became illegal speakeasies, and many common citizens took advantage of the high sales price of illegal booze by secretly manufacturing booze in their own bathtubs."? --Guy Macon (talk) 04:43, 14 September 2018 (UTC)

And don't forget the yeast-flavored grape juice that would "go bad" if you added sugar and then waited. Anyway, regarding at least the first point, it is true that the certainty on this is pretty shit, and scholars bicker over the flaws in any method, but as far as I can tell, all the indirect evidence points to a singular conclusion: alcohol consumption declined a lot. Both contemporary and modern estimates of illegal alcohol production and consumption are vastly below the surrounding time periods, arrests for public drunkenness declined by two thirds, deaths from alcohol related illnesses declined by 80%... I'd say that there are arguments that the mainstream view is wrong, or poorly supported by the evidence, and it's certainly true that all available evidence is circumstantial, but it seems pretty damned uniform in where it points: [14]. Someguy1221 (talk) 06:16, 14 September 2018 (UTC)

Deaths from alcohol related illnesses declined by 80%?

"Deaths from Alcoholism. In New York City, from 1900 through 1909, there was an average of 526 deaths annually attributable to alcoholism.

From 1910 through 1917, the average number was 619.

It plummeted to 183 for the years 1918 through 1922.

Thereafter, the figure rose, averaging a new high of 639 for the years 1923 through 1927.

Total deaths from alcoholism in the United States show a comparable trend, with the gradual increase resuming somewhat earlier, about 1922."

"These statistics should be qualified by the observations of Dr. Charles Morris, Chief Medical Examiner for New York City: 'In making out death certificates (which are basic to Census Reports) private or family physicians commonly avoid entry of alcoholism as a cause of death whenever possible. This practice was more prevalent under the National Dry Law than it was in preprohibition time' ".[15] --Guy Macon (talk) 07:15, 14 September 2018 (UTC)

80% decline is the figure from Gebhart, J. C., Statistical studies of enforcement and social effects, 1930, which is based on contemporary nation-wide statistics, though I can't find an online version. Specifically 5 per 100,000 persons per year prior, dipping to a low of 1 per 100,000 during. Notably, Gebhart was actually anti-prohibition, and believed certain causes of death were under-reported (indeed, it is today a point of contention with this type of measure that at the time, there was no consistent nationwide reporting of causes of death, and standards varied over time in particular places). Someguy1221 (talk) 07:31, 14 September 2018 (UTC)

And yet The Effect of Alcohol Prohibition on Alcohol Consumption[16] by Jeffrey Miron[17] of the National Bureau of Economic Research says "The overall conclusion of this paper is that Prohibition exerted a modest and possibly even a positive effect on alcohol consumption". So alcohol deaths dropped by a whopping 80% while alcohol consumption stayed about the same? Is there something extra healthy about bathtub gin? Or did Gebhart's 1930 figures simply reflect that during prohibition physicians avoided listing alcohol as a cause of death? --Guy Macon (talk) 12:32, 14 September 2018 (UTC)

The Miron study is however based entirely on the correlation between the number of deaths due to cirrhosis and alcohol usage (something the author somehow fails to mention in the abstract), since there is simply no real data on alcohol supply or demand in that period. The study does acknowledge one weakness of this method: cirrhosis is correlated mainly with heavy alcohol usage, and so may not be greatly effected by a decrease in casual alcohol consumption. A more solid conclusion from the study then would be to say that the number of heavy drinkers probably did not decrease significantly during prohibition. That is not to say that the total amount of alcohol consumed stayed the same. Also note that this is a working paper, so it has not undergone peer review (yet). - Lindert (talk) 13:13, 14 September 2018 (UTC)

Internation standard

Is anyone having knowledge of international quality standard that are to be followed for equipment racks and enclosures. 112.133.223.2 (talk) —Preceding undated comment added 06:24, 14 September 2018 (UTC)

Try here: 19-inch_rack#Specifications 196.213.35.147 (talk) 06:56, 14 September 2018 (UTC)

Unidentified farm crop

Can anyone help me identify the crop in this picture? Taken on 9 June at 36°20′58″N 76°59′53″W; there were a lot of fields in the area with the same crop, and I can't remember ever seeing such a crop anywhere else. Nyttend (talk) 14:00, 14 September 2018 (UTC)

Looks like clary sage to me. 216.59.42.36 (talk) 16:40, 14 September 2018 (UTC)