Wikipedia:Reference desk/Archives/Science/2016 June 5

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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[1]:

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 - [2] 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 [3]. 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 [4], and here [5] 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 [6], 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)

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 [7], 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 [8] and the other links I gave above. After more detailed searching, I finally found this [9] 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)