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June 4

Concorde

How many pages was the checklist for the Concorde jet? 2601:646:A180:C88C:F88D:DE34:7772:8E5B (talk) 00:55, 4 June 2016 (UTC)

I'm sad that the admins in your facility won't allow you to use google. It rarely does much harm. Greglocock (talk) 03:15, 4 June 2016 (UTC)

If you don't want to answer, then don't answer, but PLEASE CUT OUT THE RUDENESS! 2601:646:A180:C88C:51CE:232F:55EA:846F (talk) 05:26, 4 June 2016 (UTC)

And for the record, I DID try to look it up on Google, but all of the hits had to do with the checklists for the FSX Concorde, not the real-life Concorde! 2601:646:A180:C88C:51CE:232F:55EA:846F (talk) 05:29, 4 June 2016 (UTC)

Oh, the youtube of the braniff concorde was for a flight simulator? In that case, and that case only, I apologise. Greglocock (talk) 07:10, 4 June 2016 (UTC)

The youtube has NOTHING to do with my question -- I was asking SPECIFICALLY about the CHECKLIST! 2601:646:A180:C88C:51CE:232F:55EA:846F (talk) 22:53, 4 June 2016 (UTC)

And the youtube shows the pilot and engineer going through the checklist. So you are wrong, ungrateful and shouty. Greglocock (talk) 00:45, 5 June 2016 (UTC)

I did not watch the video, because I know that Braniff Airlines never did have any Concorde jets in its inventory -- so I naturally assumed that the video was either a fake or was one of an FSX flight mission, not a real flight! 2601:646:A180:C88C:51CE:232F:55EA:846F (talk) 03:43, 5 June 2016 (UTC)

Well to be honest I had overlooked or forgotten that little oddity as well "Braniff became the registered operator of the planes while on U.S. domestic service, and the planes were physically re-numbered with temporary adhesive vinyl. Registration was then returned to Air France or British Airways on the trans-Atlantic leg. Over American soil, the Concorde was limited to Mach 0.95, though crews often flew just above Mach 1; the planes flew at Mach 2 over open water."Greglocock (talk) 04:03, 5 June 2016 (UTC)

Considering how it ended, we might assume the checklist was at least one page short. ←Baseball Bugs ^{What's up, Doc?} carrots→ 12:35, 4 June 2016 (UTC)

Always check the runway for strips of metal that have fallen of the aircraft infront of you? LongHairedFop (talk) 14:36, 4 June 2016 (UTC)

Anyway, there seem to have been several seperate checklists: the "flight deck check" checklist, the "pre-startup" checklist, the "post-engine startup" checklist, the "taxi" checklist and the "pre-takeoff" checklist are all described in Air Crash Investigations: The End of the Concorde Era, the Crash of Air France Flight 4590 by George Cramoisi (pp. 222 - 224). Alansplodge (talk) 22:04, 4 June 2016 (UTC)

Thanks! 2601:646:A180:C88C:51CE:232F:55EA:846F (talk) 22:53, 4 June 2016 (UTC)

Species identification (tree)

Possibly misidentifed tree

The uploader supplied information for this states they weren't show if this tree was what they were told it was called. In context it's not clear if the name was a species common name or a locality one.

What's the species shown, preferably the taxonomic name?Sfan00 IMG (talk) 13:11, 4 June 2016 (UTC)

Possibly a Banyan tree? ←Baseball Bugs ^{What's up, Doc?} carrots→ 13:29, 4 June 2016 (UTC)

I google-imaged "banyan tree in Havana" and several items came up, some of which look to be this very same tree. ←Baseball Bugs ^{What's up, Doc?} carrots→ 13:35, 4 June 2016 (UTC)

Florida strangler fig (Ficus aurea) is native to the area. Rmhermen (talk) 23:39, 4 June 2016 (UTC)

Our article for Ficus aurea gives higuerón as an alternative name for the species (the reference for that refers to Costa Rica) which is not too dissimilar to "Holguín" which the poster of the image thought was the name. Also our banyan article lists the Florida strangler fig among the "many banyan species". Alansplodge (talk) 17:34, 5 June 2016 (UTC)

Hydrogen apocalypse

According to Hydrogen, it "is very rare in the Earth's atmosphere (1 ppm by volume) because of its light weight, which enables it to escape from Earth's gravity more easily than heavier gases". So if hydrogen were a bit heavier, like oxygen or nitrogen, and thus stayed on Earth, and considering its hazards, the life on Earth would have been in danger (assuming that if the hydrogen weight is theoretically increased to permit its stay on Earth, it would still be hydrogen)? 93.174.25.12 (talk) 18:01, 4 June 2016 (UTC)

Why would a proton be any heavier in hydrogen than in other atoms/molecules? ←Baseball Bugs ^{What's up, Doc?} carrots→ 18:10, 4 June 2016 (UTC)

@Baseball Bugs:dreams of possible armageddons. what if HIV became airborne, what if worldwide anti-social sentiments and philosophies became dominant...FAMASFREENODE (talk) 18:38, 4 June 2016 (UTC)

What has that got to do with the mass of a proton? ←Baseball Bugs ^{What's up, Doc?} carrots→ 19:10, 4 June 2016 (UTC)

The problem with hypotheticals is they're hypothetical. To make hydrogen heavier you'd have to do one of two things: add particles to the hydrogen atom, or change the mass of the proton and/or electron. Considering the first case, if you add neutrons you get heavier isotopes of hydrogen, but all except deuterium are unstable. Adding electrons gives you hydrogen ions, but that doesn't change the atom's weight to any meaningful degree because electrons have a tiny mass, and you can only add so many before the nucleus can't hold on to any more. If you add other particles you wind up with something that's not hydrogen anymore. In the second case, you'd change all of physics and chemistry, so it's hard to make predictions about what the universe would look like. But, it's worth noting that we already have a fairly dangerous gas present in large quantities on Earth. It's called oxygen. You're only able to survive around large amounts of oxygen because you're descended from life that adapted to it. When photosynthetic organisms started producing oxygen in large quantities, it killed all the life that couldn't adapt to it or hide from it. And even still, too much oxygen can injure or kill you. Oxygen is so reactive we have to station people throughout our communities to jump into action when it starts reacting too vigorously with things. --71.110.8.102 (talk) 20:01, 4 June 2016 (UTC)

With excess hydrogen Earth may have turned into a planet looking more like Uranus. Some lifeforms can make use of hydrogen using hydrogenase enzymes, so life may still be possible. Graeme Bartlett (talk) 22:44, 4 June 2016 (UTC)

I didn't really think about that aspect, but you point out another issue. Terrestrial planets like Earth are, well, terrestrial because they form closer to their star(s) where it's too hot to for hydrogen and helium to condense. Planets that form beyond the frost line can hold onto these gases. Since most "ordinary matter" in the universe is hydrogen and helium, they get huge. Since the resulting planets have no solid surface, they're not generally believed to be capable of supporting life, although some exotic ideas have been floated. So if proto-Earth had been able to hold onto hydrogen, life probably wouldn't exist on Earth. --71.110.8.102 (talk) 07:37, 5 June 2016 (UTC)

• If we think of a planet with greater mass but a similar size to Earth (say, a heavier core) so that its escape velocity is higher, then the hydrogen gas may be prevented from escaping the atmosphere. (Rather than hypothesising some new form of hydrogen, upping gravity seems to me more in line with the OP's intent.) Now, if the H₂ level gets high enough for sustaining combustion / explosion in air, then lighting a match could be pretty devastating. If the level of H₂ were kept sub-explosive, however, say by more hydrogenase-using organisms, then living with hydrogen would be possible. We get by with 1 ppm at the moment, a higher but stable level from a balance of consumption / loss and production is not unreasonable, IMO. Also, a planet with high H₂ but little if any O₂ would be unsuited to life on Earth as it is now, but there was life on Earth without much O₂ before, so it isn't impossible. EdChem (talk) 09:09, 5 June 2016 (UTC)

This is almost off topic for the RD, since it's one of those how much wood would a woodchuck chuck kind of questions. Still, we have a somewhat comparable situation with atmospheric methane, which is heavy enough to mix much more with the atmosphere. The reason why we don't get a 'methane apocalypse' is that fire is not truly all or nothing; there is a little bit of the essence of fire (by which I mean combustion, really) throughout the atmosphere. What I mean by this is that free radicals, in this case specifically the hydroxyl radical, get produced by the continual impact of ultraviolet rays from the Sun (in this case this is indirect, I think, via excited oxygen reacting with water). There is a whole wild layer of dilute free radical chemistry, including the famous ozone layer, high above the Earth, but actually the hydroxyl radical is much more widely distributed, and lasts only a short time wherever it is found. So what would happen in a fire happens above the Earth, but much more slowly and without the drama. Similar processes exist in many other systems, such as our bodies - but it is only in a few rare systems, like the degradation of unsaturated oils in rags, where this can cross the boundary to spontaneous combustion. Wnt (talk) 13:08, 5 June 2016 (UTC)

So if you're tired of your train rails taking years to burn put them in pure oxygen. Fwoosh! Sagittarian Milky Way (talk) 01:07, 8 June 2016 (UTC)

this user enquires the signs and symptoms of a serotonin-devoid nervous system

replies should contain as much data in-reply and not collections of external linksFAMASFREENODE (talk) 18:34, 4 June 2016 (UTC)

Replies should contain links to sources. ←Baseball Bugs ^{What's up, Doc?} carrots→ 19:11, 4 June 2016 (UTC)

"This user" could always go somewhere else if they aren't happy about this being a reference desk. Nil Einne (talk) 02:08, 5 June 2016 (UTC)

Interesting article [1], cites [2]:

"To do this, they developed “knockout” mice that lacked the ability to produce serotonin in their brains. The scientists ran a battery of behavioral tests. Interestingly, the mice were compulsive and extremely aggressive, but didn’t show signs of depression-like symptoms. Another surprising finding is that when put under stress, the knockout mice behaved in the same way most of the normal mice did. Also, a subset of the knockout mice responded therapeutically to antidepressant medications in a similar manner to the normal mice. These findings further suggest that serotonin is not a major player in the condition, and different factors must be involved. These results could dramatically alter how the search for new antidepressants moves forward in the future, the researchers conclude."

Also see [3] (2012, the older idea) Wnt (talk) 13:14, 5 June 2016 (UTC)

June 5

Appias albina and Appias albina semperi

Does anyone know if these are the same species? We have an article for Appias albina, and the name seem to be used interchangeably with Appias albina semperi in the resources that I've been able to find. --Pine^✉ 02:59, 5 June 2016 (UTC)

In ordinary nomenclature, A.a.semperi would be a subspecies of A.albina. Any reason not to assume that's the case? —Tamfang (talk) 08:36, 5 June 2016 (UTC)

Yep, here is a 2010 study on the distribution of the species, as well as some taxonomic info and discussion of the many subspecies. It gives Moore 1905 as the naming authority for semperi, and says: "females of all sub-species are highly variable and both A. albina pancheia and A. albina semperi have striking seasonal forms." SemanticMantis (talk) 13:50, 6 June 2016 (UTC)

Screw held under spring pressure

In general there's three ways to secure a screw/bolt[4]:

Case 1: Unsecured

Case 2: Semi-permanently secured, e.g. loctited

Case 3: Permanently secured, e.g. positively locked with a safety wire

Which of the three above general categories does a screw held under spring pressure (case 4) fall under?

When there's very little spring pressure it's no different than no spring at all, so let's consider the case where the spring is held under high tension. Johnson&Johnson&Son (talk) 03:18, 5 June 2016 (UTC)

I suggest a rapid investigation of the boltscience website. To some extent all bolted joints resemble your 4th case, but intentionally adding a compliance is rarely done in production these days on hard joints. Spring washers (etc) are anathema in properly designed hard joints. Electrical engineers still use them when they want to mash copper wire against steel, it seems to work, but then they often seem to use huge threads for the job in hand.Greglocock (talk) 03:55, 5 June 2016 (UTC)

On a Carburetor the adjustment screws for idling mixture and throttle position are typically secured by springs against movement under engine vibration while allowing deliberate manual adjustments. AllBestFaith (talk) 18:21, 5 June 2016 (UTC)

A screw or bolt tightened down against a compressed spring would fall into case 2, Semi-permanently secured, since it's not unsecured and it's not locked. Several ways to ensure the absolute locking of a screw or bolt are: with a lock wire, a Split pin (aka Cotter (pin)), or a flange or bracket butted up tightly against the head of the bolt and locked with its own bolt or screw to the item through which the bolt passes. There may be other methods but I can't think of any right now. Akld guy (talk) 20:56, 5 June 2016 (UTC)

I suggest

Case 2A: Semi-permanently secured allowing adjustment at any time, e.g. loaded by a spiral spring.

Case 2B: Semi-permanently secured until seal e.g. Loctite is broken. AllBestFaith (talk) 10:51, 6 June 2016 (UTC)

What turtle species?

What is the species of this turtle/tortoise? Bubba73 ^{You talkin' to me?} 04:13, 5 June 2016 (UTC)

What are its approximate dimensions? ←Baseball Bugs ^{What's up, Doc?} carrots→ 04:49, 5 June 2016 (UTC)

It looks like one of the painted turtles. Richerman (talk) 09:52, 5 June 2016 (UTC)

Could be a cooter.--Jayron32 20:02, 5 June 2016 (UTC)

Approximate size, from my memory from yesterday, probably 13-14 inches long and 8-9 inches wide. Also, in southeast Georgia. Bubba73 ^{You talkin' to me?} 21:20, 5 June 2016 (UTC)

This Link will ask you a few questions about the turtle and should narrow it down to the one you have pictured. 50.253.212.229 (talk) 01:57, 6 June 2016 (UTC)

Thanks, I might be able to answer the questions from the photos.Bubba73 ^{You talkin' to me?} 02:06, 6 June 2016 (UTC)

I couldn't answer question #4 because I didn't look at its underside. When I did the search with what I had, it didn't come up with an answer. Bubba73 ^{You talkin' to me?} 02:17, 6 June 2016 (UTC)

I sent six photos to the Georgia Department of Natural Resources - they should be able to tell me. Bubba73 ^{You talkin' to me?} 02:36, 6 June 2016 (UTC)

If you'd linked to the photos here we might have had a better chance - for example, we can't count all the scutes around the edge using just one. Wnt (talk) 10:15, 6 June 2016 (UTC)

Atomic numbers and solid state

How it came that the atomic numbers of, say, lithium, beryllium, boron and carbon are smaller that in nitrogen or oxygen, and yet they are solids while nitrogen or oxygen with larger atomic numbers are gases? I'd expect that the heavier the element, the more likely it would be in a solid state. --93.174.25.12 (talk) 07:09, 5 June 2016 (UTC)

First off, to be pedantic, any element can be a solid, liquid, or gas under the right conditions. Anyway, what phases an element takes under different conditions is determined by its electron structure. It's the electrons that determine the chemical behavior of an atom, because they're the things on the outside. See: periodic table, periodic trends, atomic orbital, state of matter. --71.110.8.102 (talk) 07:24, 5 June 2016 (UTC)

• Compare the solid structures: Li and Be are metallic solids, with an infinite array of metal ions surrounded by a delocalised sea of electrons. Melting / boiling such a structure takes a lot of energy as there are strong electrostatic forces of attraction to be overcome to separate each atom from the bulk; B and C are network covalent solids, with an infinite array of atoms held together by strong covalent bonds. Again a large amount of energy is required to melt / boil as covalent bonds must be broken; by contrast, nitrogen and oxygen are covalent molecular substances with individual diatomic molecules held together by only very weak dispersion forces. Separating N₂ and O₂ molecules from each other requires little energy, and the gaseous form leaves these individual molecules intact. The energy to separate them into atoms is high, but separating the molecules from each other requires little energy. The state at room temperature depends primarily on the solid / liquid structures. Covalent molecular structures are by far the most likely to be gaseous, especially if they have only dispersion forces, though the molecular mass is certainly a factor. For example, the BP trend of CH₄ < SiH₄ < GeH₄ < SnH₄ goes with molar mass, as would F₂ < Cl₂ < Br₂ < I₂. However, H₂S < H₂Se < H₂Te < H₂O - water is the heaviest but has the highest boiling point as it has hydrogen bonding between the molecules which the others do not. EdChem (talk) 09:01, 5 June 2016 (UTC)

A big ecosphere

An ecosphere

All these sealed ecospheres seem to be small and everything eventually dies. If it were big, could things live longer or even forever in one? Anna Frodesiak (talk) 07:44, 5 June 2016 (UTC)

Biosphere --TammyMoet (talk) 09:15, 5 June 2016 (UTC)

Well, looking at that picture it seems obvious that the dead plant didn't grow in it, so as it decays inevitably the system has to fall apart. Wnt (talk) 12:49, 5 June 2016 (UTC)

From reading the article I think that's a piece of coral. Richerman (talk) 18:43, 5 June 2016 (UTC)

It seems to me that something lives in any terrarium. That is, even if the large plants die, there's still lots of bacteria that continue to exist there. However, if we want large plants (and even animals), then you need a huge habitat for each, in order to survive and reproduce long term. StuRat (talk) 18:54, 5 June 2016 (UTC)

Sorry about the misleading picture, but that is the idea. It's a sealed glass ball with life inside. From what I've read, it works for a while then everything dies. But these are always small balls. What if they were like the size of a room. Do you think life would continue for hundreds of years or indefinitely, rather than the usual maximum of seven or so? Anna Frodesiak (talk) 20:26, 5 June 2016 (UTC)

And the article says "...Freshwater closed systems...require nothing more than...a few cups of lake or river water, and mud or other substrate...with exposure to sunlight from a window...found to contain living organisms even after several decades...eventually an equilibrium of micro-organisms is established..." Do you think it could go on indefinitely? Anna Frodesiak (talk) 20:31, 5 June 2016 (UTC)

• @Anna Frodesiak:, the principles involved include the size, the diversity, and the source of free energy, among others. In general, the larger the habitat, the better, especially because it allows for a higher biodiversity. You are better off with a large number of species of small organisms, rather than one plant and one fish. If you have 20 species of plants and algae, ten herbivores, a few predators (scavengers are good--every fishtank needs a snail that eats algae) and some decomposers that is better and more stable. See trophic pyramid.

You also need to make sure that the light source varies over time, as this will encourage mixing of nutrients. See thermocline and lake stratification. Without mixing, you will often develop a eutrophic surface, and an anoxic hypolimnion, or "dead zone".

Don't keep all your eggs in one basket. Big organisms are to be avoided. Consider having one elephant, versus hundreds of species of rodents, insects and so forth, all with the same body mass. The latter combination is much more stable. Finally, consider Biosphere 2, and the fact that they could not make it a year with humans in a very large closed environment. μηδείς (talk) 02:29, 6 June 2016 (UTC)

Taking a big breath.... Ignore Biosphere2. I took an interest in this when the experiment was still running. Don't quote me on this but the big problem was that the concrete parts of the structure was still absorbing CO2. Meaning that the oxygen content of the atmosphere became the equivalent of living at an altitude of 12,000 to 14,000 feet. The occupants where slowly suffocating. At the time there was a big debate around whether is allow more oxygen into the Biosphere so as the experiment could continue. In other words, Biosphere2 was not truly hermetic – it incorporated a positive drain. Second part of @Anna Frodesiak: query as to whether a bigger 'ecospheres' would maintain life indefinitely:.. Example: It is not only cities that produce smog. Even jungles produce, aromatics, methane and other hydrocarbons that under sun-light create toxic chemical smog. However, our planet is not seal in a glass envelope. All those chemicals eventual rise into the upper atmosphere where they get bombarded with ultraviolet radiation and get broken down into chemicals that biolife benefit from. If mankind, ever establish colonies on the Moon or Mars you can bet that they will have something like a platinum catalytic coveter that brakes down these gases. I think Skylab had such a unit to deal with all the farts, so it is not new technology. Incorporate all this into a 'ecosphere' (including the chemical buffering that oceans and land mass provide) and an 'ecosphers' may just work – (but don't include any animals called Homo sapiens. They seem just too good at messing up any given ecology). --Aspro (talk) 17:24, 6 June 2016 (UTC)

I guess you stopped reading mid-sentence, Aspro, since I described Biosphere 2 as a failure. Given your talk of space colonies and air scrubbers, you are not answering Anna's actual question, since you are including other sources of free energy to you closed system. The simple answer to the one she posted is, "Yes, the bigger the better." μηδείς (talk) 17:33, 6 June 2016 (UTC)

First: There is no such thing as a failed experiment. Second: The ecospheres pictured has an energy input already, in the form of light to support the phytoplankton. Entropy is both a necessary and given requirement this scenario. It is the first principle that one is taught in 101 Biology. UV rays are one of the necessary ways on this planet of introducing such entropy. So no. Bigger is not better. It is other things other than size that matters.--Aspro (talk) 18:26, 6 June 2016 (UTC)

Aspro, you are affirming things I have not denied. I didn't think it was necessary to explain to anyone who can edit WP that the globe was transparent, since light was a necessary source of free energy. Did you pay any attention at all about the need for mixture, and how this can be accomplished by alternation in illumination. And do you seriously deny that ceteris paribus a larger such ecosystem is more viable than a smaller system? I gave links to relevant articles and tried to pice together a helpfully coherent explanation. I am not here to be contrary or score points against straw men. μηδείς (talk) 20:58, 7 June 2016 (UTC)

Think you're getting confused with lag time. Larger volumes would be expected to have longer lag-times but that variable is not necessarily better. As you admitted, the Biosphere 2 experiment was terminated early, despite the very large volume - which you declare to be better. If a very small ecosphere had a small spark-gap ionizer or platinum catalyst to brake down the toxic products of metabolism, those little shrimps may live longer. This is the sort of technology that is being considered for human exploration to Mars. The volumes being considered are far far smaller than Biosphere 2. So I stand by what I said. Size is far from the main consideration.--Aspro (talk) 18:18, 8 June 2016 (UTC)

Thanks, Aspro, that's a bit more reasoned answer. At this point, I would simply ask, do you agree that in a glass micro-ecosphere, such as the one pictured, would not one with twice the volume, an ceteris paribus (all else equal) remain viable longer? μηδείς (talk) 01:07, 9 June 2016 (UTC)

Long term fallout effects of nuclear war

What would be the long term fallout effects of nuclear war? I'm able to find out about nuclear winter and electromagnetic pulse caused by nuclear war on Wikipedia, but nothing about the long-term radioactive fallout effects. I want to find out about stuff like how long areas hit by nuclear and thermonuclear weapons would stay radioactive for, and also about winds spreading around nuclear fallout to other areas. — Preceding unsigned comment added by Uncle dan is home (talk • contribs) 08:23, 5 June 2016 (UTC)

• Chernobyl exclusion zone might give you a starting point. EdChem (talk) 08:49, 5 June 2016 (UTC)

You may be interested in The Effects of Nuclear Weapons, compiled and edited by Samuel Glasstone and Philip J. Dolan for the US Department of Defense in 1977, and The Effects of Nuclear War for the Office of Technology Assessment in May 1979. On a lighter note (?), I also found COCKROACHES WOULD NOT SURVIVE AN EXTREME NUCLEAR FALLOUT which references an earlier work called Would the Insects Inherit the Earth?: And Other Subjects of Concern to Those Who Worry about Nuclear War (this is available for free download if you look for it, but I'm not sure how legally).

We also have a Nuclear fallout article, for a reasonable overview and some good references. Alansplodge (talk) 12:00, 5 June 2016 (UTC)

The craters themselves can remain ... unwise ... for some time - [5] But see Nuclear weapons and the United States - over 1000 nuclear weapons set off at the Nevada Test Site, and 100 above ground! Now they offer monthly public tours. The fallout came down all over the U.S., but aside from having to build Geiger counters out of low-background steel salvaged from sunken German battleships, people scarcely seemed to notice. And I'd hazard a guess that over the next decade and a half, nuclear war is going to get a whole lot more thinkable than it has been. Wnt (talk) 14:04, 5 June 2016 (UTC)

• Cobalt bomb might be a good place to start. It explains how different types of nuclear bombs produce ionizing radiation and radionuclides of different types. Some bombs, like Tsar Bomba produce mostly fusion products, this creates radiation with a very short lifespan, and hence little long-term danger from fallout for those not killed by the blast. Fission bombs may produce nuclides with long half-lives. Hence the radiation is slower to decay, but also less dangerous in the short-term.

Cobalt has a medium length half-like of about 5 years. This is particularly destructive, because it means one can't leave a radiation shelter for quite some time. That is, after 5 years a dose of radiation which might have killed you in 30 minutes might kill you in an hour. μηδείς (talk) 02:05, 6 June 2016 (UTC)

Micrandrena online species key

Hello! I have caught a species of Andrena, subspecies Micrandrena, and would like to identify her, with an online key (it must be free to access). this Biodiversiy Ireland key says they are "difficult to distinguish from one another", so there may not be one online. I have no camera good enough to show you her, but are any of the three species rare or uncommon so I can have an approximate answer? Thank you anyway, Megaraptor12345 (talk) 18:35, 5 June 2016 (UTC).

By the way, I've searched Google and stuff like that, but, alas, they were no help... Megaraptor12345 (talk) 07:32, 6 June 2016 (UTC)

It seems "Micandrena" is a subgenus, not a subspecies, according to usage here [6]. I'm a little confused what you've done, so I will ask some questions:

You've used the sort-of key you linked to be sure it is Andrena, but you can't figure out which species it is using that resource is that right? If so, then it's not one of the three easily identifiable ones. That guide is actually very good, and using keys is rather hard in this context. Are you willing to learn a fair bit of bee anatomy and specialized vocabulary? Even if you had the best key in front of you, your next question might be "is this pronotum elongated or robust?". I say this not to discourage you but just to report that getting species ID in an insect genus that is known to be tough is... well, tough.

Here is some additional info on the genus with good illustrations [7], and here [8] is a key that may not work due to range restrictions.

The other approach is to go to your local library, and request the book indicated in the slide set via interlibrary loan. You also might consider contacting local experts or even Adrena experts. E.g. if you search for recent papers on Adrena in Ireland [9], you'll see many hits. I'd think you might have some luck if you indicate your interest in the genus and ask for a copy or any good info on keys. But be prepared to 1) have requests ignored 2) be told the only good key is the one mentioned in the slide set that is not free or online. SemanticMantis (talk) 15:08, 6 June 2016 (UTC)

Sorry, I meant subgenus... :(. But I am well initiated in the arts of insect identification, read my page for more information. To answer your questions: 1) Yep 2) Already know all that stuff, for example I have identified with precision 15 Species of Irish Collembola, using key from a book by Steven Hopkin. Thanks anyway, Megaraptor12345 (talk) 17:53, 6 June 2016 (UTC)

June 6

Wingless flies

How is that some flies are wingless, like the sheep ked and the New Zealand batfly? Heegoop, 5 June 2016 (UTC)

Reading the articles about them, it appears they don't need them. ←Baseball Bugs ^{What's up, Doc?} carrots→ 02:50, 6 June 2016 (UTC)

The same way that anything living is anything: evolution. The species' ancestors experienced selection pressure against the trait of having wings, because they came to fill ecological niches where wings didn't do any good. Same reason you don't have thick fur and a tail (I assume!). Growing something you don't need wastes resources, which reduces your fitness. --71.110.8.102 (talk) 03:01, 6 June 2016 (UTC)

Yep. There are of course many flightless birds, and consider that ants are basically flightless wasps (and queens and males still fly but only briefly before they lose their wings). Many moths are flightless, especially females. The females of many firefly species are flightless, though they are of course actually beetle. My point is that loss/diminishing of wings or flight ability is relatively common in the animal world, and especially in the insect world. Brachyptery is the term for this reduced wing status, and aptery is the term for total wing loss, both coming from the Greek- πτερόν ‎(pterón, “wing”). SemanticMantis (talk) 14:52, 6 June 2016 (UTC)

What do you calla fly with no wings? A crawl. 86.191.126.192 (talk) 08:43, 6 June 2016 (UTC)

Which is related to the barfly, known to go on pub crawls. StuRat (talk) 15:50, 6 June 2016 (UTC)

If you crossed one with a regular fly, you might get a political fly: It would have only a right wing or a left wing. ←Baseball Bugs ^{What's up, Doc?} carrots→ 12:49, 6 June 2016 (UTC)

Relatedly (at least in my head!) I have often wondered why male mammals have nipples. They serve no purpose and are presumably resource expensive to grow and maintain. Maybe there is insufficient selective pressure for us to lose these? Maybe evolution is in the process of getting rid of these - it would be nice if there were medical records indicating a gradual reduction in size. DrChrissy ^(talk) 15:10, 6 June 2016 (UTC)

There is an article on vestigiality that may help. uhhlive (talk) 15:36, 6 June 2016 (UTC)

A side conversation involving the urethra and size of genomes, but not containing anything about wingless flies.

Male mammals have been around for tens of millions of years, so if there was an evolutionary advantage to losing nipples, it would have happened by now. I attribute this to be a case where the cost of adding special genes to eliminate nipples in males would be more expensive than just creating the nipples. Evolution does seem to favor as few genes as possible, so males and females are more similar, genetically, than you might expect. Facial hair, for example, is also present in females, it's just lighter and thinner. Breasts are also present in men, just smaller. The clitoris is just a tiny penis, without the urethra inside it. We actually see something similar in manufacturing electronics, where it's often cheaper to make a device with everything needed for any version, and just disable those items not needed in each particular version. StuRat (talk) 15:58, 6 June 2016 (UTC) The Genome size of just the flowering plants spans three orders of magnitude. Many insects have larger genomes than many mammals. There is not general or obvious trend in genome size, nor in pressures that increase or decrease genome size. "Evolution does seem to favor as few genes as possible" why would you say a thing like that? I can't even figure out why you'd think it would be true. Some researchers have suggested that there may be pressure to reduce genome size in certain obligate parasitic endosymbionts [10], but this is by no means a general phenomenon. SemanticMantis (talk) 16:22, 6 June 2016 (UTC) First we have that the number of genes in the human genome so much smaller than expected: "There are an estimated 20,000-25,000 human protein-coding genes. The estimate of the number of human genes has been repeatedly revised down from initial predictions of 100,000 or more as genome sequence quality and gene finding methods have improved, and could continue to drop further." Then we have specific instances of genes being reused for other purposes, such as the FOXP2 gene, reused from the animals we evolved from, and single genes which cause a suite of traits, such as red hair and freckles. Also see homology (biology), where similar traits in different species presumably relate to similar genes. StuRat (talk) 16:46, 6 June 2016 (UTC) Those are all interesting articles but none of them says anything about smaller genomes being favored over larger ones. Maybe to you they evince a certain feeling? I guess that at least explains why you might think that the quoted sentence is true, so thanks for that. But you still have not in any way supported the claim that smaller genomes are favored. It is interesting that many experts expected the human genome to be bigger, and it's also interesting that the corn genome is about 10x bigger yet. But that says nothing about smaller (or larger) genomes being generally favored. The vast majority of research on factors that influence genome size is related to endosymbionts, like this [11] and the other links I gave above. After more detailed searching, I finally found this [12] paper, that suggests there are important periods of both increase and decrease in genome size, and that genome reduction may have been very important in consolidating lineages at the dawn of eukaryotic evolution. Note most of the focus is still on archaea and endosymbionts. They do not say smaller genomes are favored though, they do say that growth and reduction of genome are both important factors in long term evolution. I happen to find this all very interesting but the main point of my comment starting with the quote from you is that you're phrasing your opinions as fact, again/still. Please stop, or if you must speculate, at least please use a WP:OR tag to mitigate the damage. SemanticMantis (talk) 18:25, 6 June 2016 (UTC)

brushed DC motor control

if you connect a small DC motor to a speaker and twist the shaft, there's a buzzing sound. could this be used to infer the number of revolutions (i.e., the angular position in multiples of 360° or 120° or 90°) a running motor has made, i.e. like a fork sensor plus disk with holes-type setup, but without it? Asmrulz (talk) 02:15, 6 June 2016 (UTC)
PS something with comparators perhaps? is this reliable?
PPS is there a single word for the disk with holes that interrupts the light in a fork sensor? Asmrulz (talk) 02:16, 6 June 2016 (UTC)
PPPS I don't have an oscilloscope (and I'm afraid to use my soundcard because of inductive kickback), but my understanding is that the transient processes inside a motor manifest as a (dirty) sinusoid on top of the DC voltage, i.e., ripple. The amplitude of the ripple gets smaller the higher the mechanical load on the shaft, but the phase and frequency correspond (in one way or antoher) to the motion of the rotor, correct? Asmrulz (talk) 02:41, 6 June 2016 (UTC)

The classic brushed DC motor works fine in reverse as a generator. A cheap one will generate a pulsating DC signal, but the pulses are far from sharp. You'd probably want to try and clean them up a bit with a Schmitt trigger or maybe even a phase-locked loop before trying to feed them to a digital counter. I wouldn't expect this to be reliable, which is one reason why motors with built-in encoders are commonplace. You might find some reading on the older AC techniques of synchros and resolvers to be of interest.

There's also the problem of speed vs. torque. Brushed motors are low torque devices so are often run at high speed with gearing to their output. The encoder is then placed on the low-speed output shaft. This makes best use of both device's optimum speed: the motor runs fast, the encoder measures position directly. When motors are used directly, they're usually some multi-pole brushless form as they have better torque than a brushed motor.

The disc is often just called an encoder disc, no special name, and may be distinguished as a relative encoder, rather than an absolute encoder. Absolute encoders will tell you position when first turned on (but are more complex). Relative encoders will either tell you only speed, or may infer absolute position if they can pick up some zero point. You will also see quadrature encoders, where there are two sets of holes, phase shifted by 90º (you can find a pair of these in an old mechanical mouse with a ball). This allows direction to be determined, so are more useful for absolute position.

Are you measuring position or speed? The techniques often vary, accordingly. Some encoder types are adequate for speed, but not position.

Try to find an oscilloscope, as you can learn an awful lot from one. Second hand 30 year old scopes are cheap in the West and still very useful - my bench scope is the same 20MHz dual trace delayed sweep design I started with as a telephone apprentice in 1982. It's fine for the sort of hobbyist / Maker stuff I mostly do (If I need better I borrow friend's). You can also buy pocket-sized flat panel 'scopes from China now (try eBay) for £20-30 and these are very handy for field work. Andy Dingley (talk) 10:31, 6 June 2016 (UTC)

The article Rotary encoder describes devices for encoding the angular position (absolute) or motion (incremental) of a motor shaft. The OP's idea is for a Brushed DC electric motor to serve as its own rotary encoder. If there were no commutator the back EMF from the motor would be a sinusoidal voltage of 1 cycle per whole revolution, identical to a simple AC generator. However the brushes and commutator switch successive windings so that only a part of the cycle is seen. The number of repetitions depends on the number of commutated windings in the motor construction; more windings means a higher ripple frequency (as a multiple of the r.p.m.) but smaller amplitude because a smaller angular range of the mentioned 1 cycle/revolution is sampled. I conclude that the idea requires tracking very small electric load variations that depend on the motor construction, that change greatly with r.p.m. and mechanical load, and will only give incremental position information. To sense absolute position an additional optical or mechanical sensor, such as a limit switch, will be needed. Using a PC with soundcard as a digital oscilloscope has limitations of no low frequency response DC - 50 Hz, no calibration, and the audio inputs should be protected against overload with series resistor 10 kohm, back-to-back diodes 1N4148 and series capacitor 1 µF. AllBestFaith (talk) 10:39, 6 June 2016 (UTC)

A further option would be an oscilloscope board which plugs into a PC - like the sound card idea, but with a front end that's better designed for this use. They can be handy for multi-channel inputs where you need to log and compare many signals. Andy Dingley (talk) 11:54, 6 June 2016 (UTC)

That's exactly right - I want the motor to double as its own encoder. Incremental is ok (I'll have limit switches for self-calibration on power-up.) Thank you for the soundcard tip! Asmrulz (talk) 12:39, 6 June 2016 (UTC)

I'm measuring (trying to, anyway) position (number of revolutions since the motor was powered.) You are right about the oscilloscope. It's like in Plato's cave without one! Asmrulz (talk) 12:39, 6 June 2016 (UTC)

Compact cassette drive

Asmrulz, when a brush connects a coil of the rotor, the voltage drops depending on its load and the power supply. When it disconnects, an inductive burst occurs. Operating a hand drill, you see the blue sparks between brush and rotor. On cheap compact cassette players the drive drive motor noise affects the sound output. A small ceramic capacitor located next to the motor blocks much of the noise. A little better design, sometimes without additional componects reduces the noise dramendously. Buck converters rectify this burst for current output, see also current doubler. --Hans Haase (有问题吗) 21:01, 6 June 2016 (UTC)

thanks! what if there's no space for a capacitor (I understand it must be "electrically close" to the motor)? can I run the leads from the motor through a ferrite bead instead? Asmrulz (talk) 16:38, 7 June 2016 (UTC)

Asmrulz, see the picture of the tape drive. Some noise is being killed with this capacitor. Else, note how to connect the wires to the supply. Use capacitors with low ESR. Wires are no supra conductors. See each of them as a resistor. Doing so, You kan kill the noise. Old soundcards in the 1990 on the ISA bus, fed the 12 volts to a 9 volts linear voltage regulator to cut the noise from the motors. I guess the load and wiring might be complicated in Your case. On a PC power supply for example, use another arm of cables or if possible choose another rail. A filter behaves like a preresistor to the motor. Too small electrolytic capacitors may get hurt from negative voltage bursts. Smaller capacitors were choosen as ceramic type, resisting a higher voltage and having a low ESR. Ferrite will be overfeed and beginns to be useful in MHz frequency range. --Hans Haase (有问题吗) 19:28, 8 June 2016 (UTC)

Falcon Rocket Guidance for landing

I'm wondering what the Falcon rocket uses for guidance to land so accurately on "Of course I still Love You". Isn't it too high to use GPS? If it is homing onto the drone ship, does it's own engine firing distort the homing signal? Thanks 49.197.26.168 (talk) 07:56, 6 June 2016 (UTC)

I think this is the article you want: attitude control system. Maybe inertial navigation system too. As for GPS, the GPS satellites orbit way up there. See picture. "ISS" is the space station. Why do you think engine firing would affect the signal? It's a chemical rocket. The engines don't put out any significant electromagnetic interference, I think. --71.110.8.102 (talk) 08:36, 6 June 2016 (UTC)

Interesting question. GPS has capabilities (high speed, high altitude) that are only available to the Western military, to avoid North Korea etc. using them to control missiles. It would be interesting to know if Falcon is permitted to use these. Andy Dingley (talk) 10:33, 6 June 2016 (UTC)

I assume this is about Falcon (rocket family) ? One problem is that they probably can't use most off-the-shelf GPS systems, which would assume that they were on, or near, the surface of the Earth, and may well give an error if it calculates a position in low-Earth orbit. So, they would need to use, or create, a GPS system which allows for that. StuRat (talk) 13:15, 6 June 2016 (UTC)

How about some references? First, as our article (and many others around the internet) notes, GPS is involved in the guidance process. The US government maintains a website full of info about GPS; here's their page about space-based applications, which specifically notes usage on things like ISS return vehicles. StuRat is correct that a space-qualified system would need to be used, but that's probably more for safety certification than it is for capability set (though perhaps that, too). Remember also that the highest precision for landing a Falcon is needed at the end of the landing, when speeds are lowest -- while there's probably an additional error component at high speeds, the corresponding high distance from target will also raise the tolerance for error. Further, we have an article on the various types of GPS signals. While there is a military component to the GPS system, it's used for anti-jamming and anti-spoofing purposes; it does not materially impact accuracy. Selective Availability, the capacity for the US government to degrade the accuracy of civilian GPS receivers, has not been used since the Clinton administration and post-2007 satellites do not even have the capability, so tracking accuracy is not a concern for the North Korean missile program -- the far harder engineering matter is making use of that tracking data. Finally, I would expect that there's some sort of radar-type backup or parallel guidance system for the final approach. As above, at orbital speeds, positioning is largely a matter of the pre-planned orbital mechanics (and radar can work out to that range, too) and so centimeter-level accuracy isn't needed at that phase of the mission. — Lomn 14:37, 6 June 2016 (UTC)

It is true that Selective Availability is no longer used, but there is still ... some technical capability that allows planned, scheduled activity that may make GPS unreliable or unavailable. For example, tomorrow, June 7, 2016, GPS will be unreliable for most of the Western United States (NTTR GPS 16-04). This activity will recur for several days over the next month. It is not particularly uncommon for GPS "outages" to take place within about a 400 mile radius from "that area."

Nimur (talk) 21:16, 6 June 2016 (UTC)

@Nimur: Are you sure it's Groom Lake (or even something to the northeast of it?) rather than the Nevada Test Site? You know, if your county had been hit by that many nuclear weapons from the air, they'd be messing with GPS too! Wnt (talk) 23:05, 6 June 2016 (UTC)

The specific notice I linked earlier - like many similar GPS outage notices - was published by FAA. It references the Nevada Test and Training Range (NTTR); its GPS coordinates, or rather, its latitude and longitude, are explicitly specified in the published NOTAM. You can also refer to !GPS 06/016, KZOA A0292/16, using your favorite database tool, such as FAA's NOTAM search engine. As they say in all the textbooks, always review all available resources prior to using GPS. There have been plenty of other center-points for GPS outages - in places like China Lake, Beatty, and elsewhere; it just so happens that the one in effect tomorrow is centered here.

Groom Lake is an unofficial official name for the dry lake bed that shows up on charts of that region; you may know the area by many other names, depending on your attention to detail.

Nimur (talk) 00:58, 7 June 2016 (UTC)

All the photographs of the barge shows two domes. I can't see a 'differential GPS base station' (which gives cm accuracy) but they are very small toroidal antenna. So most likely the barge had both GPS and radar. Think the thing to do is email Elon Musk directly. He is the sort of guy that would even remember off- the-top-off-his-head which walmart store he bought the rocket's paint from and would be happy to reply to such a simple question.--Aspro (talk) 00:49, 7 June 2016 (UTC)

Those domes are the satlinks for live video. This is why the video usually drops out then the stage is nearby, vibrations throw off the satlinks and connection is lost. This has been discussed to death, there is no feedback from the OCISLY, it is inertial+GPS from the stage to predetermined coordinates. In flight 15, when the sea conditions were too severe for landing and there was a thruster problem with the barge, it was moved out of the way, and the stage made a water landing, exactly the same trajectory, there just wasn't a barge at the predetermined coordinates. Fgf10 (talk) 07:06, 7 June 2016 (UTC)

Thanks for all your comments and refs, particularly Fgf10. Question answered! Original Poster49.197.104.167 (talk) 07:15, 7 June 2016 (UTC)

an organism feeding by rotten organic matter which their name suffix with "phagus"?

What is the name of the organisms feeding by rotten organic matter? It should be something with suffix of "phagus". I have tried to search this question on Google, but nothing I found. 93.126.88.30 (talk) 22:22, 6 June 2016 (UTC)

See http://www.onelook.com/thesaurus/?s=*phage.—Wavelength (talk) 22:42, 6 June 2016 (UTC)

Saprophagous seems to match what you're asking for. Other terms (without the -phagous suffix) that may be relevant are scavenger and detritivore. Deor (talk) 22:45, 6 June 2016 (UTC)

Thank you! 93.126.88.30 (talk) 23:20, 6 June 2016 (UTC)

June 7

Logarithm of a dimensioned quantity

From Moment magnitude scale:

$M_{\mathrm {w} }$ is a dimensionless number defined by Hiroo Kanamori as

$M_{\mathrm {w} }={\frac {2}{3}}\log _{10}(M_{0})-10.7,$

where $M_{0}$ is the seismic moment in dyne⋅cm (10⁻⁷ N⋅m).

How does it make sense to take the logarithm of a dimensioned quantity and end up with a dimensionless one? 86.171.42.219 (talk) 00:19, 7 June 2016 (UTC)

It makes sense in three cases. The first case is when you are looking not at the value of the logarithm, but at the changes (differences) of that value as a function of something else. For example, a logarithm of signal power is not very useful, but a change in a logarithm of signal power is a measure of the signal attenuation, see decibel. Indeed, difference of logarithms is the same as a logarithm of a ratio, and a ratio of two values of the same quantity (e.g. power) is dimensionless. The second case is when you have a scale, or a fixed standard unit, of a quantity that you take a logarithm of; as in your own example above. In that case you are really taking a logarithm not of a dimensional quantity, but of that quantity divided by that standard unit, which in your case is (10⁻⁷ N⋅m). --Dr Dima (talk) 01:10, 7 June 2016 (UTC) Oops I forgot explain the third case. The third case is when an additive constant is unimportant. For example, entropy is a logarithm of the number of microscopic states availavle to the system at or near its total energy value. "At or near" means that you count the states within a certain (small) energy range, so it is a dimensional quantity, depending on how narrow this energy range is. However, this multiplicative factor of the number of available states becomes an additive constant once you take a logarithm; and that additive constant is not important as it does not affect any of the thermodynamical propoerties of the system. Hope this helps. --Dr Dima (talk) 01:16, 7 June 2016 (UTC)

Thanks. Do you mean to say that "$M_{0}$ is the seismic moment in dyne⋅cm" does not mean that $M_{0}$ is a dimensioned quantity, having units of dyne⋅cm, but is a dimensionless quantity because it has been divided by the reference level of 1 dyne⋅cm? That would make sense with the logarithm (like in decibels), but that is not, to me, what it seems to say. 86.171.42.219 (talk) 01:51, 7 June 2016 (UTC)

Yes, that sort of usage "in dyne⋅cm" means that the variable itself is considered dimensionless. --69.159.60.83 (talk) 05:37, 7 June 2016 (UTC)

I will note that other logarithms of quantities are dimensionless; for example pH is the negative logarithm of H⁺ concentration. Concentration has a measurement of mol/L, but pH is dimensionless. In chemistry, the way that this is worked around is that some measurements are specifically defined as relationships of Thermodynamic activity, which is a) defined as unitless and b) quite literally not directly measurable, so impossible to determine directly. Concentration is used as a sort of "surrogate measurement" in calculations involving the impossible-to-measure concept of "activity", such as both pH and equilibrium constant. So, we say that pH is the negative logarithm of activity, which is unitless but unmeasurable, and so we use molar concentration as a "stand in" for the calculation, since we can measure that, and at low enough concentrations, activity and concentration are proportional anyways. I'm not sure how this works with moment magnitude, but that's the sort of hand-waving we use in chemistry. --Jayron32 05:41, 7 June 2016 (UTC)

Personally, I would tend to write:

$M_{\mathrm {w} }={\frac {2}{3}}\log _{10}\left({M_{0} \over 1\,{\text{dyne-cm}}}\right)-10.7$

or even:

$M_{\mathrm {w} }={\frac {2}{3}}\log _{10}\left({M_{0} \over 10^{16.05}\,{\text{dyne-cm}}}\right)={\frac {2}{3}}\log _{10}\left({M_{0} \over 10^{9.05}\,{\text{N-m}}}\right)$

Which are all ways to describe the moment magnitude, if one treats $M_{0}$ as a dimensioned quantity rather than treating it as dimensionless. However, it isn't uncommon to see formulas presented in such a way that you are expected to take some variable as its dimensionless value in some units (especially in engineering), but personally I find those presentations rather annoying and suboptimal. Dragons flight (talk) 06:27, 7 June 2016 (UTC)

In physics, one doesn't specify in which units quantities have to be filled in in a formula. As long as one uses the basic units of a consistent system of units, the result comes out of the formula in basic units of the same system, whether that be SI or cgs or any other system. Imperial or American customary units are not so consistent, so that becomes very messy and those are avoided in science. If there is a logarithm in the formula, one has to make sure one takes the logarithm of a dimensionless quantity. If it's not dimensionless already, one has to divide by some constant of the same dimensions to make it dimensionless. For sound levels, one divides by a standard flux of $10^{-12}\mathrm {W} /\mathrm {m} ^{2}=10^{-9}\mathrm {erg} /\mathrm {cm} ^{2}$ to calculate decibels, for stellar magnitudes one divides by the flux of Vega. From a theoretical point of view it would make more sense to use some constant of nature, but that's not always practical.

In this case, the explanation going along with the formula suggests a particular unit. This is an implicit way of stating that one should divide by a standard quantity equal to unity when expressed in this particular unit. I would write:

$M_{\mathrm {w} }={\frac {2}{3}}\log _{10}\left({\frac {M_{0}}{M_{\mathrm {std} }}}\right)-10.7$

with $M_{\mathrm {std} }=1\,\mathrm {dyne} \cdot \mathrm {cm} =10^{-7}\,\mathrm {N} \cdot \mathrm {m} =0.08856\,\mathrm {firkin} \cdot \mathrm {furlong} ^{2}/\mathrm {fortnight} ^{2}$ a standard seismic moment. Or I could absorb the 10.7 term into the logarithm and use a different standard moment:

$M_{\mathrm {w} }={\frac {2}{3}}\log _{10}\left({\frac {M_{0}}{M_{\mathrm {std} }^{\prime }}}\right)$

with $M_{\mathrm {std} }^{\prime }=1.122\cdot 10^{16}\,\mathrm {dyne} \cdot \mathrm {cm} =1.122\cdot 10^{9}\,\mathrm {N} \cdot \mathrm {m} =9.937\cdot 10^{14}\,\mathrm {fir} \cdot \mathrm {fur} ^{2}/\mathrm {ftn} ^{2}=0.5736\,E_{\mathrm {Planck} }$. That's not a nice value in any system (although it's quite close to unity on the Planck scale), but that quantity was chosen to keep close to an earlier seismic scale, developed before seismic moments were properly understood. PiusImpavidus (talk) 10:58, 7 June 2016 (UTC)

Unless anyone can cite Hiroo Kanamori calling $M_{\mathrm {w} }$ dimensionless the gentleman is being misrepresented, because it does not make sense at all. AllBestFaith (talk) 11:32, 7 June 2016 (UTC)

It looks like the original author didn't worry about units - you see that surprisingly often; many people just want to plug numbers into formulas without thinking about them as carrying units with them. What gets interesting is that I would think you can actually carry unit analysis into the realm of logarithms (even though that article explicitly states that they are undefined!) For example, you might say (assuming base 10 for the moment) that log (10 N m) = 1 + log N + log m. You could write something like log m = 2 + log cm or log N = log kg + log m - 2 log s, I think. In which case we could "fix" the above formula by adding "- log N - log m" at the end of it. Note: don't do this! Use Dragons flight's second formula instead, as it has the minor advantage of being sane. But you should be able to, I think. Wnt (talk) 12:58, 7 June 2016 (UTC)

Is "10 N m" really 10 multiplied by "N" multiplied by "m"? Anyway, I find it hard to see what meaning could be ascribed to "1 + log N + log m"! 86.171.42.219 (talk) 21:57, 7 June 2016 (UTC)

I would say yes, at least in the sense that if you keep track of them you can tot them all up to 0. Now to come up with a meaning for a value of "2 + log m" on its own would be harder; yet it seems like it would be a dead giveaway that your pre-log value should have been divided by some reference value - in meters. I suppose it means it's 100 relative to the comparable exponent value for 1 meter. Wnt (talk) 00:11, 8 June 2016 (UTC)

Yes, you can think of N and m as constants equal to the ratios between those units and the "true units" (Planck units, if you like, but it doesn't matter). Then log m is simply the logarithm of the ratio, and represents a shift of the zero point from "true zero". It's not common, but there's nothing insane about it; it's an internally consistent approach. -- BenRG (talk) 02:28, 8 June 2016 (UTC)

Rate of genetic similarities

Modern academia put the DNA similarity between humans and chimps at 95%-99%, as per Human_evolution#Evidence_from_molecular_biology. And in cats, for example, it's reportedly a whooping 90% of homologous genes shared with humans. That seems quite high, as at around 90% of genetic similarities I'd expect some stronger resemblance, such as between modern humans and Neanderthals, and in cats I'd expect around 65-70%. Is it some sort of non-coding DNA that is not responsible for morphological and physiological features? Brandmeister^talk 14:02, 7 June 2016 (UTC)

All the studies make lots of suppositions - including the ones that a "minor difference" is, in fact, of little concern, and that all species have similar rates of change in DNA as their similar species have. Also, the fact is that their is apparently quite substantial variability within human DNA - vide the recent studies that a significant proportion of modern human DNA is likely inherited from "extinct pre-Homo Sapiens species". (Many people appear to have up to about 4% Neanderthal DNA, many have up to about 5% Denisovan DNA, and there is a really good chance that several other "extinct species" also have DNA found in modern human populations, and totally dwarfing the chimp DNA position). Using an analog - the difference between the Davenport electric car's "MNA (Motor Nucleic Acid)" and the Tesla Model S's MNA is extremely small indeed. Yet one might find it not that difficult to spot differences. Collect (talk) 14:20, 7 June 2016 (UTC)

• The genes that make up our appearance are only a small fraction of the total genome. Most of the enzymes and structural proteins are largely similar between all mammals, and in some cases all species. And are cats and humans really that different? Two eyes, four limbs, same internal organs etc. We have about 24% genetic homology with grapes.... (many other species here) Fgf10 (talk) 15:06, 7 June 2016 (UTC)

Trying to spell that out a little more: so many genes have to do with biochemical machinery, and this machinery is/has been broadly conserved via stabilizing selection. How to cells transport things? How do cells metabolize? Then there are many genes that have ontogenetic roles and are related to tissue and organ formation. But cats have skin, and fat, and muscle, and hair... and though those things are a little different in cats, they have most of the same tissue types and organs that work in mostly the same way. Also, homology is not identity. Finally, OP may be interested in reading up on Evolutionary_developmental_biology, aka "Evo-devo", a field that makes much of the similarities (and differences) between a fetal human and a fetal cat. SemanticMantis (talk) 15:24, 7 June 2016 (UTC)

This appears to be a handy overview of nearly all differences between cats and humans, from skeletal system to muscular, nervous, digestive, etc. If the 90% assertion on human similarity is true, are the remaining 10% able to encode all those anatomical and physiological differences? Brandmeister^talk 21:02, 7 June 2016 (UTC)

Hey that's a pretty cool slide set- thanks! My understanding is that there are two sources of differences between a cat and human. One source is that 10% of genes that occur in humans but have no analog in cats. But the other source is that the genes we "share" are not 100% identical, they are merely homologous forms. So while cats and humans have many similar genes, a given shared gene will not be identical. See here [13] for some specific examples of how homologous genes are similar different. I'm not sure which of these sources is more responsible for the differences, nor to if that question even makes sense. Also consider that by this reckoning, you and I have 100% of our genes (i.e. loci) in common, yet we have differences, due to having different alleles. I'm now past my point of expertise. Perhaps User:Fgf10 or User:Wnt can expand on this or tell me if I said anything incorrect :) SemanticMantis (talk) 15:12, 8 June 2016 (UTC)

That is a cool slide set. But it's worth adding that while "the" human and "the" cat are different, individuals may be less so. A particular human may lack a vermiform appendix, or have the left common carotid artery arise somewhere other than the aorta, thus resembling the case for the cat. But of course, all this anatomy is very roughly 100 times more ancient than the unique features of modern human beings. The truth is, we still have no idea what features make humans so unusual in their behavior, nor is any existing theory truly sufficient to rule out qualia in a rock or a computer keyboard, let alone a cat. Wnt (talk) 22:02, 8 June 2016 (UTC)

Surnames dying out

I think we have an article on this, if I could only remember what it is called. In a society where family names descend by patrilineality, at some point rarer names will die out, because sooner or later all the children in a given generation will be girls, and will not pass the name on to their children. (Ignore sexism, single mothers, and volitional name changes - this is a thought experiment.) The model that shows how this works can be applied to other things transmitted by descent such as genes. Am I mis-remembering? What is this phenomenon called, and what application does it have in current research of any fields? Carbon Caryatid (talk) 17:36, 7 June 2016 (UTC)

Galton–Watson process. --Jayron32 17:44, 7 June 2016 (UTC)

Elementary, my dear Galton! Thanks. Carbon Caryatid (talk) 18:21, 7 June 2016 (UTC)

Colloquially called "daughtering-out". - Nunh-huh 00:21, 8 June 2016 (UTC)

Does this mean that eventually everyone will be named Smith? ←Baseball Bugs ^{What's up, Doc?} carrots→ 18:50, 7 June 2016 (UTC)

I'm Brian! DMacks (talk) 18:57, 7 June 2016 (UTC)

No. Read sections 2 and 3 of the linked article, which give conditions for extinction of a name. Note that extinction in finite time is always possible, so persistence of a name for all time is necessarily a probabilistic notion. As explained in the "examples" section, real-world names seldom conform exactly to this model. And if one name was likely to increase while others diminish, smart money is on Wáng/Wong over Smith, which is actually a fairly uncommon name. SemanticMantis (talk) 19:41, 7 June 2016 (UTC)

Smith is the most common surname in America, though obviously there are a lot more Chinese than Americans. ←Baseball Bugs ^{What's up, Doc?} carrots→ 23:52, 8 June 2016 (UTC)

The article Y-chromosomal Adam says we are all patrilineally descended from a common male ancestor who lived 200,000 to 300,000 years ago. So equating the Y chromsome lineage to surnames, this implies that all other surnames that coexisted with his died out at some point (with no changing of surnames allowed). Is that right? (Also the same applies to Mitochondrial Eve). Loraof (talk) 21:27, 7 June 2016 (UTC)

That common ancestor lived hundreds of thousands of years before there were surnames. But no other man with a Y-chromosome at that time has any male descendants alive with that chromosome. - Nunh-huh 00:20, 8 June 2016 (UTC)

Sure, and in that case, the other haplogroups/surnames had a positive chance for extinction in finite time. The fact that they did die out doesn't mean they had to, and none of this means we should a priori expect one surname to eventually exclude the others. It's always possible for everyone not named Hernandez to die tomorrow, right? So we cannot ever say with certainty that a haplogroup/surname will persist indefinitely. Under the model assumptions, we can sometimes say that a given lineage will almost surely go extinct. SemanticMantis (talk) 15:02, 8 June 2016 (UTC)

What is the term for stoppage or accumulation of blood in the lower part of the body?

What is the term for stoppage or accumulation of blood or fluid in the lower part of the body or other organs? (under influence of gravity. for example by bad blood circulation or even after death). There is a word that should start with the prefix hypo-xxx 93.126.88.30 (talk) 20:07, 7 June 2016 (UTC)

After death: Livor mortis. --NorwegianBlue ^talk 20:15, 7 June 2016 (UTC)

Indeed, it is hypostasis as mentioned in the article that you linked. Thank you! 93.126.88.30 (talk) 20:34, 7 June 2016 (UTC)

Edema is accumulation of fluid (mostly water). It's commonly in the lower part of the body, due to gravity, in people who are upright most of the day. For those who are bedridden, the accumulation may be more towards the back, depending to the position of the patient. It's common to rotate the patient to even it out. Compression stockings are used to limit accumulation in the feet, but unless they have a graduated reduction in compression near the top, the patient can get the "muffin top" effect where all the accumulation pools right above the stockings. Phlebitis, an inflamation of the veins, often in the legs, is also related. StuRat (talk) 17:14, 8 June 2016 (UTC)

You might also look at Ascites. DrChrissy ^(talk) 17:25, 8 June 2016 (UTC)

I thought I might find it in g-suit but it's not there. DrChrissy ^(talk) 17:23, 8 June 2016 (UTC)

Wacom share holding stock

Would you buy a piece of the company? Is it worth - or did they stopped to built interesting things and the company was years ago more interesting for investment? --Ip80.123 (talk) 23:53, 7 June 2016 (UTC)

The Refdesk doesn't give advice, especially not professional advice. It also doesn't make unsourced predictions, especially when assuming a perfect market the existing price would be assumed to approximate the best rational estimate, within some unknown and doubtless financially interesting margin of error. If you go to Humanities and ask where to look up stock predictions they might help you though. Wnt (talk) 00:14, 8 June 2016 (UTC)

Here's some general advice about the stock market, from Will Rogers: "Buy only good stock. Wait till the price goes up, then sell it. If it don't go up... don't buy it!" ←Baseball Bugs ^{What's up, Doc?} carrots→ 00:38, 8 June 2016 (UTC)

June 8

Minimum spring outer diameter for a given wire diameter

Is there a formula, table, or some sort of back-of-the-envelop approximation for calculating the minimum spring outer diameter for a given wire diameter?

Let's say the spring wire diameter is 1 mm. A 5 mm outer diameter spring is possible given this wire size; but a 4 mm outer diameter spring would not be possible. Thus the minimum spring outer diameter is somewhere between 4 mm and 5 mm. How do I go about calculating or approximating this minimum outer diameter? Johnson&Johnson&Son (talk) 07:34, 8 June 2016 (UTC)

Yes. I use a slide rule for this. It's a specialised slide rule, given away some time in the 1970s as a design aid by a spring winding factory. If you talk to any spring maker, they will help you out with this - either with a table in their catalogue, a simple spreadsheet or computer program, or maybe even a slide rule. Andy Dingley (talk) 11:39, 8 June 2016 (UTC)

Wikipedia articles are Coil spring and Spring (device). Here is an American spring catalog search site which converts inch measurements to mm. The extended search for extension springs made of 1.0414 mm diameter wire finds minimum outer diameter 5.9436 mm in stock. AllBestFaith (talk) 13:21, 8 June 2016 (UTC)

Question about sperm temperature

A mans nutsack is on the outside of the body because sperm die if they are too hot, right? Otherwise they'd be kept safe inside his body instead of dangling dangerously outside. So how come when he puts his sperm inside the womans belly to make her pregnant the sperm don't die from the internal heat of the woman? (I assume men and women measure the same temperature?)

Basically how come the sperm die at body temperature inside the man, but don't die inside the woman? 200.94.21.194 (talk) 18:42, 8 June 2016 (UTC)

It's not that sperm die at body temperature; it's that spermatogenesis doesn't work as well. Sperm also travel through the male's body during ejaculation (note: NSFW images in article), so even before entering the vagina they already encounter higher temperatures. (Also, "nutsack"? Maybe use "testicles" on the science desk?) --71.110.8.102 (talk) 22:04, 8 June 2016 (UTC)

Maybe the OP was talking about this kind of thing. And speaking of "spilling seed", the OP should be advised that the methods illustrated in that secnd article are unlikely to result in impregnation. ←Baseball Bugs ^{What's up, Doc?} carrots→ 22:29, 8 June 2016 (UTC)

Baby spiders

I recall reading back in the '80s in The Encyclopedia of Igorance (eds: Ronald Duncan, Miranda Weston-Smith) about an experiment involving baby spiders with results that could not be explained by known mechanisms. The experiment was simple: hatch spiders in a controlled environment, devoid of any food or water source. Soon their mass and volume will greatly increase (I forget the stats) -- it was (is?) unknown how they were able to create the complex molecules presumably from "thin air". --Has this since been explained? ~107.15.152.93 (talk) 20:04, 8 June 2016 (UTC)

I don't know about that study, but I remember reading that some baby spiders catch pollen and dust on their webs, and that can sustain them. Graeme Bartlett (talk) 22:34, 8 June 2016 (UTC)

How does capillary phenomena play a role in eye irrigation and nosebleeds?

1) I have read the following phrase in the book "Nano-Surface Chemistry" (p.289) "Capillary phenomena are also essential in tribology and in many biological systems, such as blood circulation and eye irrigation". How does it plays role in eye irrigation? 2) In a English-Spanish I've read: "Nosebleeds are caused by the rupture of a small blood vessel called a capillary in the nose." Is there any relation between the capillary phenomena to the rupture or to the mechanical going of the blood outside? 93.126.88.30 (talk) 23:37, 8 June 2016 (UTC)

Elements 119-120

Now that official names of elements 113-118 have been proposed to become standard, can anyone find out what's going on with elements 119 and 120 (the elements of the next row of the s-block)?? By the end of 2016 some of the labs should start working on trying to create these elements whatever way they can. Georgia guy (talk) 23:43, 8 June 2016 (UTC)

Does human body have a surfactant in another place in the body except of in the lungs?

or it is the only one surfactant in the body? 93.126.88.30 (talk) 23:49, 8 June 2016 (UTC)

I expect there are many, and many compounds will have some surfactant behaviour even if it's not their primary function. One obvious one leaps out though, and that's bile, which emulsifies fats as part of the digestive process. Andy Dingley (talk) 01:11, 9 June 2016 (UTC)

"oxgen glass" for spherical spaces?

49.135.2.215 (talk) 01:08, 9 June 2016 (UTC)Like sushi

"cubical quadratic"?

49.135.2.215 (talk) 01:12, 9 June 2016 (UTC)Like sushi

"quarcal scizars" binding electron"?

49.135.2.215 (talk) 01:13, 9 June 2016 (UTC)Like sushi