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October 24

Duckweed on ponds

I was surprised to see the rather sharp boundary between duckweed and no duckweed: I would have expected the raggedy zone to be several feet at the minimum, or the fountains to cause enough movement to prevent duckweed growth over a far wider area. Any ideas why the raggedy zone is so small, why the fountain water is so suddenly unable to prevent weed growth? Nyttend (talk) 04:32, 24 October 2014 (UTC)

The majority of the duckweed plants are single organisms with two or four leaves which reproduce largely by cloning. They are not rooted to the bottom or connected by branches. The separate plants are not connected, so they float as individual particle on the surface, and are subject to the dynamics any other unstructured surface covering would be. Unfortunately our main article just mentions the diversity of form in a chart, but there's no description section. μηδείς (talk) 05:03, 24 October 2014 (UTC)

might have been that those fountains were recently switched on for some reason after a long period of duckweed growth? only explanation i can think of atm for the sharp boundary ~Helicopter Llama~ 12:14, 24 October 2014 (UTC)

In my experience, the little roots of individuals often get intertwined, leading to clumps of many individuals that are attached to each other. Carefully separating one individual is the hard part. I often see it with fairly sharp boundaries. It's not that the fountain is preventing growth, it's just a steady push, roughly radially uniform, so you get a roughly uniform boundary where the surface flow outward drops below the a certain level necessary to counteract the other sources of random flow. Also, I can't tell for sure from the photo, but it looks like the duckweed forms a pretty continuous mat to the edge of the pond. So the fountain is basically just pushing out until all the duckweed is compacted against the edge. Each little clump pushes on each each neighbor, and most plants will be effectively connected to the edge in this way. From that perspective, little random jostles from the fountain would tend to increase packing density and smooth out the boundary. SemanticMantis (talk) 13:54, 24 October 2014 (UTC)

• There are five genera of duckweed, and I don't know how many species, they do have quite different morphologies. I don't doubt some "entangle" but the ones I remember from swimming in the lake as a kid didn't do so. I think its safe to assume in most cases they will act enough like ideal particles confined to a plane (the water surface) and repulsed by the fountain. What I want to know is, why haven't the maintainers of this pond gotten a pair of ducks with their flight feathers clipped to remove the eutrophication? μηδείς (talk) 23:28, 25 October 2014 (UTC)

Wind turbine on a car

If we setup a wind turbine or several wind turbines on a car, will the turbines harvest more energy than the energy spent to run the car? roscoe_x (talk) 08:34, 24 October 2014 (UTC)

No in general, but yes if the engine is turned off. Dbfirs 08:44, 24 October 2014 (UTC)

Also see Conservation of energy, First law of thermodynamics (you can't win), and Second law of thermodynamics (you can't even break even). But, as Dbfirs has pointed out, one could recover some energy when using wind resistance for braking. Unless I'm very much mistaken, it's much more efficient to do that via the wheels, however, and that is indeed done. --Stephan Schulz (talk) 09:45, 24 October 2014 (UTC)

Assuming the air relative the moving car is at rest, the wind turbines will feed off the car's fuel. This is because the expenditure of fuel is causing the car to move, and the moving car is causing a relative air current, which is moving the turbines. Thus you're actually consuming more energy than without the turbines. Even in an ideal universe where there is perfect energy conversion, you'll still only break even, creating a perpetual motion machine. Only in the case where you are trying to actively decelerate the car by converting its linear momentum, can the turbines generate energy. Plasmic Physics (talk) 10:37, 24 October 2014 (UTC)

Also see automotive aerodynamics; efficiency is improved by reducing air resistance, whereas a wind turbine will massively increase it.--Shantavira| 12:06, 24 October 2014 (UTC)

Plasmic Physics' first sentence is key — it's possible for the car to generate more energy with the turbines, but it requires wind, which is independent of the car's engine. The point is that you must have outside input, whether wind or something else, in order to generate more energy than is produced by the engine alone. After all, a sailing ship (potentially) has no engine at all, but it's still able to generate energy by using the wind. Nyttend (talk) 12:17, 24 October 2014 (UTC)

Indeed. And there are Wind-powered vehicles that show unintuitively good performance - the Blackbird can go downwind faster than the wind! --Stephan Schulz (talk) 12:34, 24 October 2014 (UTC)

Fairly sure this has been discussed at least once and I think more than once before. Nil Einne (talk) 13:19, 24 October 2014 (UTC)

Yes, probably within the last month. As Dbfirs and others indicate, the only way this might work is to not use an engine, but rather to put sails on the car and possibly capture some of the wind for use with other things. However, as with a sailboat, you would have to tack if the wind is against you, and if there's no wind at all, you're stuck. With actual wind turbines, I think it would only work if the wind is behind you. ←Baseball Bugs carrots→ 14:28, 24 October 2014 (UTC)

No and no. There is no need to tack, and you can go any direction you like (in theory). See the articles on Wind-powered vehicle and Blackbird I linked below. A simple way to understand at least the plausibility is to mentally separate power generation and movement. While the vehicle stands, its wind turbine is charging a battery (or flywheel, or whatever). Then it uses that stored energy to go wherever it wants. Doing it on the fly and with purely mechanical means is the same thing, only without the dog. --Stephan Schulz (talk) 14:51, 24 October 2014 (UTC)

How does a sailboat move toward the wind without tacking? ←Baseball Bugs carrots→ 19:46, 24 October 2014 (UTC)

A narrowly defined sailboat probably can't (although I can easily do something with a wind turbine and two anchors). But a wind-driven vehicle can drive directly into the wind - and do so at much more than the speed of the wind, too. Check the articles I linked. In particular, a wind turbine can extract energy from the wind and use it to drive wheels even directly against the wind. --Stephan Schulz (talk) 20:47, 24 October 2014 (UTC)

Some previous discussions Misplaced Pages:Reference desk/Archives/Science/2014 July 24#Alternate Fuel and Car Technology (second part), Misplaced Pages:Reference desk/Archives/Science/2010 July 21#Wind Turbines on Cars, Misplaced Pages:Reference desk/Archives/Science/2010 June 11#Windmill on a car?, Misplaced Pages:Reference desk/Archives/Science/2007 October 15#Possibly to make a hybrid/tribrid car that captures wind energy?, and also a small amount of discussion at Misplaced Pages:Reference desk/Archives/Science/2009 March 31#Electric car & Misplaced Pages:Reference desk/Archives/Science/2010 January 25#wind turbine generator manufactures. I think the key points were already covered here by PP, StS and Nyttend and others. Everyone agrees that you it will be dumb to try and recover anything from the movement of air solely arising due to the movement of the car. There is some disagreement over whether you're likely to ever generally get a net gain (compared to any added fuel cost from carrying the turbine and possibly increase drag) when the air is already moving relative to the car, i.e. if there is already wind. Of course this will also depend on how windy the place is. Nil Einne (talk) 16:37, 24 October 2014 (UTC)

The point is that the EXTRA air speed that comes about from the motion of the car doesn't help you at all...the extra drag would at best cancel out the energy from the windmill - and in truth, because nothing is every 100% efficient, it'll be much worse. So the only energy could possibly be harvested from the wind itself. Now you have a situation where a hypothetical zero-weight, zero-friction, lossless windmill would generate exactly as much net energy if it were bolted to the ground as it would on the car. In any practical sense, the windmill that's bolted to the ground will generate much MORE net energy than one bolted to the car because the car doesn't have to haul the extra weight around, or suffer the net drag.

If this is an electric car (and I guess that's a part of the assumption here) - then it's VASTLY more efficient to buy a windmill, bolt it beside your house and use it to generate electricity that you use to power your house or run your electric meter backwards. The energy you save can then be used to charge your car battery whenever it's parked at home. You don't have to haul the windmill around with your car - and you can situate it to better face the prevailing winds - and it doesn't have to be lightweight or low drag. Better still, it's saving on your energy bill even when your car is parked in the garage. SteveBaker (talk) 19:32, 24 October 2014 (UTC)

Really? If the air is moving relative to the ground, you can potentially harvest substantially more net energy from a wind turbine of a given area by moving it, by virtue of the larger volume of air with which it interacts (and hence kinetic energy of the wind that it can extract). —Quondum 22:44, 24 October 2014 (UTC)

But the drag on a moving body is proportional to the square of the speed - and that erases that benefit. The laws of thermodynamics definitely apply here. SteveBaker (talk) 03:51, 25 October 2014 (UTC)

Until you've quantified the drag relative to the power extracted, such a statement makes no sense at all. This is a reference desk; let's keep what we say here on firm ground (no pun intended). —Quondum 21:34, 25 October 2014 (UTC)

Cotyledon function

Quoting from our Cotyledon article: "Cotyledons may be either epigeal, expanding on the germination of the seed, throwing off the seed shell, rising above the ground, and perhaps becoming photosynthetic...."

1) I take this to mean that some epigeal cotyledons do not become photosynthetic. Is this true?

2) If they become green, does that mean they are photosynthesizing?

3) Are dark green leaves better at photosynthesis than lighter green ones?

4) a)Are cotyledons that DO photosynthesize as efficient at doing so as the "regular leaves" of the same plant? b) Can they be photosynthesizing but only weakly such that removing the cotyledons actually improves the growth of the plant?

Thanks, C7nel (talk) 18:33, 24 October 2014 (UTC)

I took the liberty of numbering your questions for ease of reference.

1) This page says that this plant in the Stemonaceae has non-photosynthetic cotyledons.

2) Yes, in general. Chlorophyll is green, and I'm not aware of any other green pigment in plants.

3) Not in general, but it depends on what you mean. "better at photosynthesis" depends on several factors. One is if the plant does C3 photosynthesis or C4 photosynthesis or even CAM photosynthesis. Other factors are leaf area index, specific leaf area, quantum efficiency, temperature, concentration of atmospheric CO2, and many other things. The biotic factors can vary between species and between plant functional types. The abiotic factors can vary based on time and location. One loose trend for forest species is that understory growth tends to be a bit darker than the canopy, and this is basically because most of the light is diffuse and scattered, instead of direct from the sun. But all bets are off if you compare plants from radically different taxa and having very different morphologies.

4) a)Roughly - if anything the are probably better. That's the plant's first chance to get started in life, so they better make it good. b)Probably not. There is a notion of competition for light between ramets of a plant, but in general the plant makes its own best decisions. Removal of the cotyldons removes total photosynthetic area, and also causes damage that leads to water loss, and also removes non-structural carbohydrates, nitrogen, and other resources that the plant can use. Most cotyledons don't hand around that long, and when they wither and fall, the nutrients have already been retranslocated to use in other parts of the plant. We don't have a WP article on retranslocation, but see e.g. these lecture notes .

Hope that helps, SemanticMantis (talk) 19:30, 24 October 2014 (UTC)

SM has pretty much covered this all. I would point out the two halves of the "nut" of an acorn as an example of epigeal cotyledons which really don't photosynthesize, although they may turn a little greenish, while cannabis cotyledons do serve as the first pair of quasi-leaves. It's never a good idea to remove cotyledons, they contain fat and protein that the leaves don't have in abundance and which is the plant's limiting growth factor at that point. Even if brown and ugly they'll drop off at the right time, and removing them won't encourage growth. μηδείς (talk) 20:57, 24 October 2014 (UTC)

The acorn example is better than the weird plant I linked above. Come to think of it, the nut meat in e.g. pecans, walnuts, etc. are also cotyledons. But I can't easily figure out if they are only used as storage organs or if in some species they do photosynthesize... SemanticMantis (talk) 13:05, 27 October 2014 (UTC)

Bird chirp sounds like water sloshing?

Today I heard a very strange bird chirp that sounded like water sloshing around followed by a click. I was unable to see the bird clearly as it was up in the trees. I live in southern Arizona of the United States. Would you happen to know what bird it might have been? -- Tohler (talk) 22:17, 24 October 2014 (UTC)

I'd point out that there are a lot of birds like crows and mockingbirds that are mimics, and they sometimes mimic sounds made by inanimate objects/machines, assuming this isn't a "normal" call. If no one here offers a likely answer (I'm an Easterner) you can also ask at WikiProject Birds. μηδείς (talk) 00:19, 25 October 2014 (UTC)

October 25

Ebola virus cure

Please give me a quick lesson on the Ebola virus. I am confused about this one issue, in particular. This has happened in the news quite a few times in the recent past. A person gets the Ebola virus. Then, a few days later, you see in the news that they are now free from the virus. I thought there was no cure for the Ebola virus. So, how do some of these people go from having it one day, to not having it the next? Thanks. Joseph A. Spadaro (talk) 01:17, 25 October 2014 (UTC)

If you read ebola virus disease you'll see that this outbreak, while much bigger, seems to have a slightly lower mortality rate, which, ironically, means more people may die because the infectious people stick around longer. I am not sure where you are getting the notion that people are diagnosed then quickly cured.

In the US we have had the option of transfusions from people who survived the virus (a few early volunteer workers) whose blood still caries the antibodies that successfully fought off the disease. These transferred antibodies don't themselves cure the Ebola, they prime the victim's body more quickly, and successfully to ramp up their own immune response. (If you are sick, and get antibodies from another patient, those antibodies will stick to the virus particle in your bodies, telling your white cells "this is an invader, react to and destroy it.". As the virus is attacked, your own body will react to the broken-up viral particles, and you will produce more and different kinds of your own antibodies, and quicker.) But they are still sick for a few weeks while they fight it off. If you have a source that indicates some sort of "quick" full cure in a patient you should link us to it.

Even recovered patients are still infectious for some period (they have the virus under control, and are getting better, but it is still in their bodies.) There has been a suggestion that they extend the quarantine from a 21-day symptom free to a 28-day symptom free period and talk of recommending the use of condoms for 90 days after the end of symptoms. I can get refs for that if necessary. Otherwise, the point is that getting better does not happen over night, even in people who receive transfusions. μηδείς (talk) 01:35, 25 October 2014 (UTC)

You asked me: I am not sure where you are getting the notion that people are diagnosed then quickly cured. What I am referring to is this. There were a few doctors and nurses who got Ebola while they were working in Africa. They came to get treated at hospitals in the US. And then the news reports that they don't have the disease anymore. In fact, just today, the same thing happened with that nurse Nina Pham. She got the disease from that Duncan "patient zero". And it's all over the news today that she no longer has the disease. In fact, she went to the White House and took photos with the president. Those types of situations, I am referring to. Thanks. Joseph A. Spadaro (talk) 01:45, 25 October 2014 (UTC)

Nina Pham seems to have been exposed to the virus on or before Sep 28, to have become symptomatic on Oct 10, and been declared "virus free" on Oct 24. That indicates two weeks with the illness, and she of course was given antibodies from survivor Kent Brantly before Oct 13. This would mean a four-week infection with a "cure" in 11 days, although her own body would have been ramping up fighting the virus before she became feverish, which is a sign of an immune response. I won't pass judgment on the wisdom of a government agency declaring someone asymptomatic and rushing them to the White House for a photo-op. μηδείς (talk) 01:59, 25 October 2014 (UTC)

Like many viral illnesses (e.g. common cold, influenza), an Ebola infection is relatively short-lived after the appearance of symptoms. Typically, patients are acutely symptomatic for only 4-10 days. After that the typical patient is either well on the way to recovering, or already dead. There is no cure, but in about 30% of cases the victim's immune system simply fights it off. In the US, with access to advanced supportive care and specialized treatments (e.g. survivor antibodies) the survival rate so far is much better than in Africa, perhaps more than 80%. Dragons flight (talk) 03:10, 25 October 2014 (UTC)

It's kinda like a race - the virus is multiplying like crazy in the body - but the body is making antibodies as fast as it can. These two systems are multiplying their respective numbers as fast as they possibly can. In some diseases, it's no contest - the antibodies wipe out the virus without problems...but in Ebola, it's a very close thing. The 30% of people who survive are able to produce enough antibodies to reduce the number of viruses and eventually eliminate it completely. The 70% who die don't produce them fast enough, and succumb to the symptoms before they can significantly reduce the amount of virus. After a week or two, you either produce enough antibodies and recover...or you die. The lucky ones wind up with a massive number of antibodies in their bloodstream - which wipes out every last trace of the virus - so they can move back into society with no risk to the people around them...they are also immune to further ebola infections. Those who aren't so lucky spread virus in every bodily fluid in increasing amounts as the disease takes over - and even their corpses are lethally dangerous to everyone who comes into contact with them.

There is no cure - except what the human body can do all by itself, if the conditions are right.

It's believed that providing good, old-fashioned care for the patient (food, water, IV bags, etc) increases their ability to generate antibodies just a little bit faster - and that sways the odds in their favor. An expert I was listening to on the radio this morning claimed that with first-class hospital care, the death rate might be pushed down as low as 20%...but without it, 70% to 90% would be the expected number.

SteveBaker (talk) 03:49, 25 October 2014 (UTC)

A-ha. OK, now I get it. So, there is no medical cure. The only real cure is the body curing itself (which happens in some patients, but not in others). Joseph A. Spadaro (talk) 04:10, 25 October 2014 (UTC)

Perhaps you mean no medicinal cure, as in a pill carrying a chemical. But a transfusion of antibodies from a recovered patient most certainly is a medical treatment. People getting that treatment have a much higher chance of recovery. But nothing in medicine is without caveats and exceptions. μηδείς (talk) 04:20, 25 October 2014 (UTC)

Yes, exactly. Thanks! Joseph A. Spadaro (talk) 20:24, 26 October 2014 (UTC)

Within the last week I have seen media reports that aggressive oral rehydration therapy (up to 5 lit/day) has had a significant impact on survival rates in West Africa and is partially credited with clearing the disease from Nigeria. Roger (Dodger67) (talk) 08:06, 25 October 2014 (UTC)

I don't know the particulars of ebola well enough and I'm lazy to search, but I suspect that as with many viral diseases (or really many infectious diseases period0 good treatment doesn't just mean you generate antibodies faster, but also that you're more likely to survive until you do. Nil Einne (talk) 14:03, 25 October 2014 (UTC)

Precisely the point - good supportive therapy to maintain the patient's life while the patient makes sufficient antibodies to deal with his or her viral load is the "first-line" treatment for ALL strains of Ebola. While there is some indication that drugs which inhibit the replication of HIV can also affect the clinical course of Ebola infection, the first-line treatment of this strain of the disease is still just good nursing care. Unfortunately, this strain of Ebola is so much more highly communicable than previous strains that the "good nursing care" therapy necessarily places the good nurses needed for this treatment at risk of contracting the disease themselves. A good, safe Ebola vaccine (such as the VSV-ZEBOV vaccine - a specially-modified recombinant version of vesicular stomatitis virus modified to provoke an immune response to the same family of Ebola viruses the new strain belongs to) is the best hope not only of protecting people who don't have the new Ebola strain yet, bot of protecting nurses and doctors who are treating those ill with the disease. loupgarous (talk) 18:43, 25 October 2014 (UTC)

I'm unaware of any evidence that this strain is more communicable that previous strains. It happened to reach large urban centers which Ebola has never done before and it happened to emerge in a part of the world where funeral customs strongly encourage many people to touch the dead (which was not true in the Eastern/Central African countries where it emerged in the past). It found itself in conditions favorable to its spread, but the infectious properties of this outbreak otherwise seem similar to previous outbreaks. In many previous outbreaks doctors and nurses were also hit hard because they are among the most likely to contact the sick and their fluids. The very first Ebola outbreak in 1976 killed 41 staff in a single hospital accounting for about 1/4 of the fatalities in that initial outbreak. Many subsequent outbreaks followed a similar pattern, where a large fraction of the victims were health care workers. Dragons flight (talk) 19:11, 26 October 2014 (UTC)

Ebola vs. AIDS

This question about whether or not there is a cure for Ebola brought to my mind a question of my own. Can one recover from AIDS, which there is no cure as well, in the same way that one can recover from Ebola? I know that AIDS is a sexually transmitted disease, but they're both incurable viruses that can be contracted through contact with bodily fluids as well. So, what's the difference? Would antibodies help in fighting AIDS? If not, why not? Willminator (talk) 06:49, 26 October 2014 (UTC)

I don't believe anyone has ever recovered from HIV. Some people can not be infected, but as far as I know no one who got it has ever recovered. (The bone marrow transplant doesn't count.) HIV knows how to hijack the immune system, and hide from it, so the immune system is unable to clear it. This is in contrast to Ebola which the immune system can clear, the only question is speed: Who is faster, Ebola or the immune system.

The incurable part is that we don't have a human-created medicine for them, but they are not the same as far as the body is concerned. Rabies is the same way: We don't have a medicine for it, but the body is able to clear it, if it's fast enough. Ariel. (talk) 17:23, 26 October 2014 (UTC)

(I wrote this a few hours ago but wasn't going to post it since it's somewhat incomplete and probably not the best explaination. Still I decided I might as well post it since it may help until something better comes along.) AIDS is caused by HIV which is a retrovirus that's integrated in to the host genome (as a Provirus). As our article Virus latency hints at, it's difficult to eliminate an integrated provirus from an organism since you probably need to kill all the cells where it's integrated, even more a problem is the cells normally live a long time. This isn't to suggest only retroviruses demonstrate virus latency, as our article mentions a number of other viruses do as well. Nor is it to suggest anything showing viral latency will cause significant life long problems. Varicella zoster virus which isn't a retrovirus but does demonstrate latency causes Chickenpox and can be reactivated causing shingles, but most of the time this just means a painful but not life threatening rash. Note that the reason why you don't get chickenpox again is because the immune system is keeping the virus in check, but for reasons not completely understood, there are sometimes localised failures. To be clear, there are a number of other features which make the long term effects of HIV particularly nasty such as the fact (as our article says "infects vital cells in the human immune system such as helper T cells (specifically CD4+ T cells)" usually leading eventually to a low level of CD4+ T cells and a compromised immune system meaning even something like chickenpox can become a significant health risk (although I think shingles is usually still not that dangerous). Nil Einne (talk) 20:28, 26 October 2014 (UTC)

See The_Berlin_Patient for info about a few people who have been considered "cured" of HIV. I'm not sure why you are saying some treatments "don't count." SemanticMantis (talk) 12:59, 27 October 2014 (UTC)

Species ID

Could someone identify the species in the below pics. Filenames were given randomly as I didn't know the species ID. Thanks in advance! — Preceding unsigned comment added by Nikhilb239 (talk • contribs)

The middle flower is a periwinkle, perhaps Catharanthus roseus. μηδείς (talk) 03:22, 25 October 2014 (UTC)

The first looks like an Azalea, but it is hard to tell without a straight on picture of flower.

The third is a hibiscus, Hibiscus rosa-sinensis var.. μηδείς (talk)

You are welcome, User:Nikhilb239, μηδείς (talk) 05:29, 26 October 2014 (UTC)

Invasive species *from* North America

I'm looking for any info on any species considered as invasive where they've ended up (outside of North America) that are native *primarily* to North America. The only one that I've found is the Canadian Beaver which has become invasive in Tierra del Fuego (the trees don't copice when cut down). Any suggestions?Naraht (talk) 08:48, 25 October 2014 (UTC)

See List of globally invasive species. Animals on the list from North America are:

• Eleutherodactylus coqui, a Puerto Rican frog
• Gambusia affinis, the Western mosquitofish
• Micropterus salmoides, the largemouth bass
• Oncorhynchus mykiss, the rainbow trout
• Rana catesbeiana, the American bullfrog
• Sciurus carolinensis, the grey squirrel
• Trachemys scripta elegans, the red-eared terrapin.

The Canadian beaver, Castor canadensis, is not on the list, but see Beaver eradication in Tierra del Fuego. Tevildo (talk) 09:11, 25 October 2014 (UTC)

Fight the good fight, beavers! InedibleHulk (talk) 20:42, October 25, 2014 (UTC)

Phylloxera isn't terribly popular among grape growers around the world. HiLo48 (talk) 09:36, 25 October 2014 (UTC)

And prickly pear became quite a problem in Australia. HiLo48 (talk) 09:39, 25 October 2014 (UTC)

The Signal Crayfish isn't too popular over here.--Phil Holmes (talk) 13:36, 25 October 2014 (UTC)

mentions Aphanomyces astaci, that article links to Signal crayfish which mentions it too is an invasive species in some places. I suspect some of the other introduced resistant species are also a problem. That article also mentions Rainbow trout although the lack of much info in our article makes me think it's not generally such a big problem. Also are you only including species exclusively native to North America or any species native to North America where it's possible some of the invaders came from there? And are you including species found in coastal oceanic waters? Mnemiopsis is another example from the article. (There's also something like Didymosphenia geminata, with a very wide range and I don't know if it's well established where the invaders came from.) Note also that in fairly isolated ecosystem like New Zealand and Australia, modern thinking is generally that any introduced species which seems to be spreading unintentionally may be considered invasive, particularly in the case of plants. (E.g. some searching found Ceratophyllum demersum and I'm fairly sure there are quite a few more. Note that the first source says it's from North America, but our article suggests a wider range.) Nil Einne (talk) 13:56, 25 October 2014 (UTC)

The American mink (Neovison vison) is an invasive species in the UK. CS Miller (talk) 15:55, 25 October 2014 (UTC)

The "Louisiana red" crayfish was found in Hampstead Heath, to the chagrin of those who habitually bathe there and have been nipped by its claws and elsewhere in England with reports going back to the mid-1990s. While a nuisance to bathers in shallows where the species now lives (especially those who prefer to bathe nude), it's not so much an "invasive species" as one imported specifically because of its hardiness in biomes where European crayfish won't flourish. loupgarous (talk) 19:00, 25 October 2014 (UTC)

If you get nipped, you can get even by catching it and turning it into Crawfish Étouffée. ←Baseball Bugs carrots→ 20:18, 25 October 2014 (UTC)

I've actually advertised my services to England - fly my family and me to Hampstead Heath and we'll eat ALL those pesky crawfish up for them. As often as necessary. I remember this being an issue when I worked as a consultant in England in 1994. loupgarous (talk) 20:36, 25 October 2014 (UTC)

The issue isn't bathers toes, but the impact on the native crayfish population; "White-clawed crayfish, Britain's only native freshwater crayfish, are under serious threat from an American invader. The introduced signal crayfish has had devastating effects, both out-competing the natives and carrying a deadly fungus against which the white-claw has no defence." Catching and eating them or just catching them is being tried, but they breed faster than anybody can remove them. Alansplodge (talk) 09:06, 26 October 2014 (UTC)

P.S. I see rainbow trout was already mentioned above, sorry I missed that somehow (but not the bullfrog also mentioned in the source I used). The discussion below about the UK also reminded me for Sciurus carolinensis also mentioned above, hence why I noticed now. Nil Einne (talk) 12:09, 26 October 2014 (UTC)

In the UK:

• American oyster drill (Urosalpinx cinerea)
• Slipper limpet (Crepidula fornicata) Richerman (talk) 21:20, 25 October 2014 (UTC)

I highly doubt the latter, given the Latin name of the species, and that John Cleese was giving speaches on them in the 70's. μηδείς (talk) 05:33, 26 October 2014 (UTC)

Our article does say "species is native to the western Atlantic Ocean, specifically the Eastern coast of North America" and "invasive species in Denmark, France, Italy, the Netherlands, Spain, and the United Kingdom, and has also spread to Norway and Sweden. It is known to damage oyster fisheries. The slipper limpet has few to no predators in Europe, and can thrive on several types of hard bottoms and shellfish banks." I can't comment on speeches in the 70s, but it's hardly uncommon that some people don't agree on problems caused by certain introduced species or simply that the damage they are causing wasn't appreciated until more recently. Many invasive species were after all introduced intentionally. Nil Einne (talk) 12:07, 26 October 2014 (UTC) Edit: Fixed wrong quotation marks Nil Einne (talk) 19:55, 26 October 2014 (UTC)

You'll find them here. I did wonder about the Latin name - I presumed it meant "oversexed and over here" :-) Richerman (talk) 17:41, 26 October 2014 (UTC)

@Naraht: If you go through the pages linked from here, I daresay you'll find hundreds or thousands of relevant species. For example, here are just some of the macrophytes from North America that are invasive in German waters:

• Sagittaria latifolia
• Hydrocotyle ranunculoides
• Elodea canadensis
• Elodea nuttallii
• Vallisneria spiralis
• Lemna minuscola
• ...

I gave up after that, but hopefully you get an idea of the impossibility of listing individual example here (though perhaps a list article can/should be created). Abecedare (talk) 20:31, 26 October 2014 (UTC)

I agree with Abecedare that a WP list of invasive species who's origin comes from the New World would be informative. It must include of course a mammal (not mentioned above), that that in the last seventy years has suddenly spread to all contents including Antarctica and even further. They are very adaptive and good mimics. I have even seen them in broad daylight, doing things like, patiently waiting for the lights to change so that they can cross the road (just like we do) thus avoiding ending up like squashed hedgehogs – amazing!--Aspro (talk) 22:06, 26 October 2014 (UTC)

The NA muskrat is one that I haven't seen listed here that is a fairly common pest in EU, see Muskrat#In_human_history. SemanticMantis (talk) 12:54, 27 October 2014 (UTC)

How many asteroids with retrograde paths are there?

Hello all.
24 hours ago I was completely unaware that there are asteroids that orbit the sun in the opposite direction to the rest of 'em, and that they are believed to be clapped-out comets.
Thanks to 2000 DG8, I now know of their existence, but have no idea how many of them there are.

• Two?
• Four?
• 36, or maybe 50?
• Over 9,000?

I find this fascinating, but I think it would be a good idea to have expert eyes on this before I go ahead and make any more enthusiastic amateur edits. Pete AU aka --Shirt58 (talk) 10:21, 25 October 2014 (UTC)

There are around 50 known to exist, but AFAIK so far only six have their orbits really nailed down (20461 Dioretsa, (330759) 2008 SO₂₁₈, (336756) 2001 NV₁, (65407) 2002 RP120, (342842) 2008 YB₃, and (343158) 2009 HC82). You can tell that their orbits are securely known because they've been numbered. Double sharp (talk) 14:58, 25 October 2014 (UTC)

Depending on the minimum size you want to count, the "joke answer" of 9000+ is actually correct. The number of known retrograde asteroids seems to be around 50. The mass ratio of prograde:retrograde asteroids might be an even more interesting number.

Note that the original sources say "over 8000". - ¡Ouch! ( / _{more pain}) 07:18, 28 October 2014 (UTC)

Making a chemical from only knowing the formula

As the title suggests, simply I wish to know if it is possible to make a chemical substance, when the only thing you know is the formula for it? In this case, I have the formula C₈H₇N₃O₂, and I am trying to assess whether I can construct the chemical when I don't know the ingredients, purely by managing to work with some elements &/or compounds to reach that formula :) Thanks. CharlieTheCabbie|Yack to the driver 10:39, 25 October 2014 (UTC)

Per isomer there are often multiple solutions. However, it is often possible to do some simple detective work and come to a few possibilities or even one if you make some assumptions about stability. In your case I'd focus on the large ratio of carbon to hydrogen (8 to 7). Hydrocarbons usually have a roughly 1 to 2 ratio. That gives a hint that there might be one or more aromatic ring structures; rings of 4 and 8 are not specially stable for molecular orbital reasons (though unconjugated single-double bond rings these sizes do exist) so phenyl (C6H6) is what comes to mind. The nitrogens might also replace carbons on the ring for a heterocycle missing carbons/hydrogens; five-membered rings work for this. Another hydrogenless way is carbonyl... or nitrile. The oxygens might appear as hydroxyl (OH), nitroso (-NO2), carbonyl (-COOH) ... seems like a fair number of possibilities, though most have quite a few active functional groups and you'd have to think about their stability. If you simply want an answer, the simplest thing to do is to just go ahead and search Google with it and you'll have one. Searching PubChem gets a bunch of answers, but probably not all answers - see . Wnt (talk) 11:37, 25 October 2014 (UTC)

According to John Drury Clark, longtime chemist at and director of the Liquid Rocket Propulsion Laboratory at Picatinny Arsenal, New Jersey in his classic book Ignition!, the US Navy Bureau of Aeronautics once requested proposals for "rocket fuels derivable from petroleum."

He and other chemists were amused at this because (quoting Dr. Clark):

" 'Derivable' is an elastic term, and it is to be doubted that the higher-ups of the Bureau of Aeronautics realized what they had authorized. But the lower-level chemist types in the Rocket Branch were perfectly aware of the fact that a good chemist, given a little time and money, can derive just about anything organic, up to RNA, from petroleum if he wants to."

That's the first thing that came to mind when I read this question. In practical terms, it's easier to go to a class to learn how to do organic synthesis and take advantage of the power of metal ions to catalyze an organic reaction to make what you want, given the chemical formula for it, than to experiment and not take advantage of three centuries of other people's mistakes and real-world experience.

One of the first things you'll learn is that carbon and nitrogen have the ability to bond to other elements in complex ways, so when you look at an empirical formula such as the one you specified in your question, you don't get the information about what you want to make that Wnt discussed above. There are more complex notations for organic compounds (ones containing carbon) which show the more complex bonding arrangements common in useful organic chemicals, and some of these notations show line drawings of the way in which the molecules are made, to show you that you want to make something (for example) with the ring-like structure of benzene, phenol, or another cyclic hydrocarbon.

It takes a little more than Googling to actually be able to do even a moderately simple organic synthesis - or to even be sure of what you're trying to make. A semester of two of organic chemistry class in college WITH the associated laboratory courses are what you need.

And don't forget that Mother Nature does some of the work for you, if what you want is derived - or derivable - from a sugar, or perhaps a plant sterol. And good luck! loupgarous (talk) 21:42, 25 October 2014 (UTC)

Having said that, I took Wnt's advice myself, Googled the empirical formula you gave, and got:

Luminol (also known as "3-Aminophthalhydrazide"), a chemical useful at crime scenes for making blood and bodily fluids more visible than they usually are, and;

7-methyl-6-nitro-imidazopyridine, which belongs to the Imidazopyridines, a group of chemicals which includes at least three drugs with varying effects on the human body - one of which, zolpidem, is a very popular prescription sleep aid sold in the US as "Ambien". There's no particular information on 7-methyl-6-nitro-imidazopyridine's pharmacology that I've been able to see in a few minutes of Googling, but one team of researchers is looking at the whole class of chemicals to which it belongs for a drug that keeps cholesterol from being a problem (perhaps without beating up on the liver as much as the "statin" drugs do).

None of that's likely to help you make luminol or the other compound at home; for 7-methyl-6-nitro-imidazopyridine, I'm thinking you'd need both that organic chemistry coursework I mentioned and a proton nuclear magnetic resonance spectrometer, which they don't sell at Wal-Mart. And luminol's fairly toxic... you want to have personal protective equipment when you undertake to make it. I'd personally want to retake organic chemistry and the lab course, just to learn now to run the new equipment they have now. loupgarous (talk) 22:31, 25 October 2014 (UTC)

Luminol is not fairly toxic and NMRs are used in characterization, not synthesis. Rmhermen (talk) 17:33, 26 October 2014 (UTC)

NMRs are used to characterize the product of almost every step in an organic synthesis (at least the first few times through the route) to verify that the reaction actually did what one expected (verify that the structure is correct, etc). Once the route is established as reproducible, it can sometimes just be followed as a cookbook. DMacks (talk) 20:34, 26 October 2014 (UTC)

Is the number of the cells like the number of the tissues?

Is the number of the cells like the number of the tissues? (or: Is the number of the tissues like the number of the cells?). Please, I need a certine certain answer, because I'm going to write it... Thank you194.114.146.227 (talk) 11:49, 25 October 2014 (UTC)

In biology, a "tissue" is a group of cells that perform a similar function. Less than an entire "organ" - but much more than a single "cell". Our article Tissue (biology) describes all of this in detail. SteveBaker (talk) 22:18, 25 October 2014 (UTC)

May it be the tissue thick, or any tissue is thin?

May it be the tissue thick, or any tissue is thin? can it be that a origin has a lot of the same tissue and they are connected together, or when they are together they're considered like one tissue (of course when they are the same tissue) 194.114.146.227 (talk) 11:53, 25 October 2014 (UTC)

Some tissues are fairly thin, others very thick, or even forming a solid block. Some of the tissues that make up the skin are only a few cells thick - but brain and muscle tissues can be many centimeters thick. SteveBaker (talk) 22:22, 25 October 2014 (UTC)

what type oscillator is this

http://madlabs.info/flyback.shtml (scroll down a bit) what determines its frequency? (or rather, what is meant by "resonant frequency" (in the text), as there is no capacitor anywhere, unless it's one of the junctions of the transistor...) Thank you in advance PS I'm not into HV, arcs and stuff. I'm only curious about the oscillator PPS the Armstrong oscillator looks superficially similar, but I think the first circuit, unlike it, is some kind of relaxation oscillator... Asmrulz (talk) 22:49, 25 October 2014 (UTC)

This is a Blocking oscillator. Our article on them is, unfortunately, absolutely dreadful. This website (although a little unpolished in terms of graphic design) gives a much better explanation of how they work. Tevildo (talk) 00:06, 26 October 2014 (UTC)

What is the different between Atom and element?

5.28.181.5 (talk) 22:51, 25 October 2014 (UTC)

An element is specific type of atom. It's similar to the words "animal" and "species": an animal is an individual organism, while a species is a certain type of animal. Gold, carbon and helium are three different elements. A golden ring consists of a large number of gold atoms, which are a different kind of atom as the ones that fill a helium balloon, just like a herd of cattle consists of individuals that differ from those in an ant colony. - Lindert (talk) 23:09, 25 October 2014 (UTC)

Agreed, except that could be misinterpreted as saying an element is one atom, but it's all atoms of that type. So, you would say "That's a gold atom" or "That's a gold object". StuRat (talk) 05:27, 26 October 2014 (UTC)

An element is a description of a kind of atom...specifically, a description of the number of protons that atom has in it's nucleus. So all atoms with one proton are members of the Hydrogen element. All atoms with 26 protons are members of the Iron element. Atoms that are a part of the same element are not necessarily identical though - they can have different numbers of neutrons, and those are called 'isotopes' of that element. So all uranium atoms have 92 protons - but anywhere between 140 and 146 neutrons. Atoms of the same element can also (temporarily) have different numbers of electrons and thereby become 'ions' that are positively or negatively charged.

But most of the things that make atoms recognizable to us as distinctly different 'stuff' comes about from the number of protons - hence our obsession with categorizing them by that number. 6 protons makes Carbon that comes in a number of forms like graphits and diamond, makes an insane number of interesting compounds that are the basis of life itself...but add just one proton and you get Nitrogen, a relatively boring gas that's fairly unreactive...take away one proton and you get boron, which is a shiney black or brown metal. But add an extra neutron to Carbon...and it's still pretty much just carbon.

So it's convenient to classify all of the hundreds of kinds of atoms out there by the number of protons they have...and those classifications are what we call "the elements". SteveBaker (talk) 15:25, 26 October 2014 (UTC)

• The question is akin to asking "What is the difference between a tree and a forest?" or maybe even better "What is the difference between a wall and bricks?". An element is defined as a fundamental type of substance, which cannot by any means be broken down into simpler substances, and which is all composed of the same kind of atoms. An atom is the little building blocks we make all matter out of; an element is a substance all made of the same kind of atoms. Back to the brick-wall analogy: I can build a wall out of all identical red bricks, or I could build my wall out of a mixture of different kinds of bricks. The wall built out of the same kinds of bricks would be an "element". --Jayron32 16:43, 27 October 2014 (UTC)

To expand a bit with pictures This is a picture of some pieces of iron. Iron is an element. This is a picture of an atom of iron. --Jayron32 16:51, 27 October 2014 (UTC)

Is any winter prediction lore better than chance?

Like bushy squirrels or caterpillars? Does the entire species in an area even vary in bushiness by year? Sagittarian Milky Way (talk) 23:37, 25 October 2014 (UTC)

I can't give you a source, but I've heard that folk predictors of that type actually reflect what the weather was like last winter. ←Baseball Bugs carrots→ 01:36, 26 October 2014 (UTC)

Agreed. I certainly can accept the idea that, if an animal could predict the weather, it would behave (or grow fur) accordingly for that situation. However, I'm not convinced that animals can predict the weather better than humans. After all, they don't measure the ocean temp to determine it it's an El Nino year, chart the position of the jet stream, etc., so just how would they predict the weather ? Beyond just a few days, which they can probably predict by barometric pressure, etc., I don't see how. StuRat (talk) 03:15, 26 October 2014 (UTC)

Animals are pretty good at sensing when something is amiss, like a storm coming or some kind of threat. But they're not fortune-tellers. ←Baseball Bugs carrots→ 04:08, 26 October 2014 (UTC)

Any animal which reproduces sexually had better be good at sensing when something is a miss (or a mister). :-) StuRat (talk) 05:32, 26 October 2014 (UTC)

!!! InedibleHulk (talk) 06:12, October 28, 2014 (UTC)

It's impossible (even in principle) to predict the local weather more than a week or two in advance because of chaos theory. So these animals clearly can't be doing that. However, there are large cycles such as the 11 year sunspot cycle that they might stand a chance at - but the link between such things and local weather has not been proven. El nino cycles are too irregular (2 to 7 years) to allow a cyclic fur growth pattern to be established. But these creatures can grow extra fur really quickly, so they could certainly be reacting to subtle weather changes like air pressure and humidity and have evolved an ability to react to those changes in particular geographical locations where those changes produce predictable consequences. SteveBaker (talk) 15:07, 26 October 2014 (UTC)

Sunspot cycles are among the elements used by the Old Farmers Almanac. ←Baseball Bugs carrots→ 15:26, 26 October 2014 (UTC)

Yeah...and perhaps it's worth reading Old_Farmer's_Almanac#Accuracy...their reputation for accuracy extends far beyond their actual reliability. SteveBaker (talk) 03:12, 27 October 2014 (UTC)

Personally I have a lot of confidence in Canada geese flocks that migrate overhead, but I suppose they really don't have to predict more than a few weeks in advance. Wnt (talk) 21:53, 27 October 2014 (UTC)

Or at all. They could just be using climatic norms, daylight, or past weather. And if they did know future weeks I doubt when to leave is correlated much with the whole season. Case in point, October 29, 2011 had 4 inches of snow during the peak of foliage season. Almost the record early snowfall of any amount. I think mid-October is the record for early frosts. Not a winter for the ages. Oct 29 of 2012 had a hurricane and it did not drop below ~55 degrees from late spring to October 30th. Not a mild winter. The winter after that had up to 3 cold waves a month, 1.5 feet fell 1 week apart without really melting, snowfall was 9th out of 145 years or so, and first snow was in November and first frost was completely average (November). Sagittarian Milky Way (talk) 05:45, 28 October 2014 (UTC)

October 26

Ebola virus hardiness

How long does the Ebola virus remain infectious outside a living host (bat, human, dog, swine, or other carriers)? Ebola virus disease says that it is highly infectious on the skin of a dead victim, but for how long? The article just says it is infectious on surfaces for "a few hours." How about on things contaminated by fluids from the victim (blood, feces, vomit) on sheets, toilets, clothing, doorhandles? They went through a great effort to remove everything from the apartment of the Dallas victim's family, but if the stuff becomes noninfectious after "a few hours,"why couldn't they have just locked the door for a day or two, rather than destroying all personal belongings, carpets, etc? When sources say the virus is not infectious after so many hours, does that assume it is exposed to fresh and sunshine, while in moist dampness it could persist indefinitely? I know that some bacterial pathogens sporify such as anthrax, and can remain infectious indefinitely. What about viruses? If the infectious potential only persists for "hours" (2, 20, 200?) then why the ritual of cleaning bowling alleys, taking airplanes out of service, and sending in hazmat cleaners to apartments? Is it a legitimate health precaution or "public health theatre"? Edison (talk)

How much do we know for sure about ebola? The story seems to change daily. It reminds me of the early years of the AIDS panic. ←Baseball Bugs carrots→ 14:41, 26 October 2014 (UTC)

Yes, health officials have an annoying habit of saying "it can't b spread by X", when they really should say "we haven't yet observed it being spread by X". Now, with a disease that's been around and unchanged for thousands of years, those two are pretty much the same. But in a relatively new and rare disease/strain, you can't just assume that a means of transmission is impossible because you haven't observed it yet. StuRat (talk) 16:06, 26 October 2014 (UTC)

Your first point is completely untrue. I can virtually guarantee you that no scientist/health official has explicitly said "it can't b spread by X", and will have said "we haven't yet observed it being spread by X". It's the obnoxious media "simplifying" the accurate wording scientists use for consumption by the ignorant soundbite-expecting public. As a scientist who has had their research misrepresented in the media, I feel this is an important point to make. Fgf10 (talk) 19:05, 26 October 2014 (UTC)

Have to agree with StuRat on this. Saw it myself on TV. An expert said something along the lines that if a victim is not showing signs and symptoms then s/he is not contagious and they can safely carry on with their normal work. There is something called 'theoretical' risk. Here, in the UK, one can only exhume 'known' smallpox victims if one has had a Small Pox vaccination. Likewise, if an archaeologist is exploring a plague pit, then it is understood that there is a 'theoretical' risk of contracting Yersinia pestis. (doctors have a saying: If you hear hoofs... think horses not zebras( the common not the exotic) Meaning: A doctor would not normally consider a patient with a cough as having Yersinia pestis. But if his patient says Oh and by the way, I am an archaeologist and currently working in an old plague pit, the doctor can then switch mode and consider the possibility of plague. This is because medial science does not know exactly how long the causative agents of these two diseases remain viable. The experts on TV where pontificating about thing that they have no scientific evidence for. Yet, perhaps, the allure of appearing on TV, overcame their conservatism and good judgment.--Aspro (talk) 22:50, 26 October 2014 (UTC)

I haven't heard the statement about Ebola that "It can't be spread by X". I did hear the statement about HIV that "It can't be spread by X", in particular to "It can't be spread by insects", when the Belle Glade cluster of HIV infections still isn't explained unless it was a rare case of the virus being spread by mosquitos. Statements that "it can't be spread by X" are more appropriate to varicella or to Y. pestis, with centuries of data, than to Ebola, and by now HIV is somewhere in between. (I think that it can reasonably be said that Ebola can't be spread by mosquitos, because if it could, most of the population in Liberia, Sierra Leone, and Guinea would be infected, but no one said that it could be spread by mosquitos. That isn't an argument against effective mosquito control, because malaria is still a serious problem in those countries.) Robert McClenon (talk) 15:59, 27 October 2014 (UTC)

I had read that the virus can survive for a couple of hours on a hard, dry surface - up to 24 hours on moist/soft surfaces and an unknown, but definitely much larger, amount of time in human corpses. A lot of the caution involved here is because there are unknowns. This virus is just not that well understood - and there is always the possibility of mutant strains that can break the rules. When you're dealing with something with the ability to become an unstoppable global pandemic with a potential for deaths in the billions, an excess of caution is definitely required.

Viruses are tremendously variable in their capabilities. The HIV virus is incredibly fragile and can hardly exist outside of the human body at all. The classic Tobacco mosaic virus can live for up to nine years on a dessicated plant leaf - and can form essentially inorganic crystals that can survive for decades in a wide range of conditions - it's capable of infecting 120 different plant species in nine distinct families. I'm sure there are examples all along that spectrum.

SteveBaker (talk) 14:56, 26 October 2014 (UTC)

This virus was first written up years ago. It clearly is of interest in the public health world, and could potentially cost many lives and many billions of dollars economic disruption. It is surprising if no controlled studies were done to furnish reliable answers to obvious questions such as I posed about how authorities can do the minimum disruption to ensure some contaminated apartment, bathroom, school, cruise ship or shopping mall will not be a source of future cases. Overreaction ("public health theatre") to reassure the public seems to be the rule so far in the U.S if the statements about a few hours or 24 hours for the infection potential of fluid deposits is correct. If some animal species is infected in a similar manner to humans (lab rats, or rabbits ideally, or even swine perhaps?) it would seem straightforward to do parametric testing and determine what measures are really necessary when an infected person has deposited his bodily fluids on something. If semen remains infective for weeks after the accepted 21 days, then what about blood? Ebola survivors are welcomed a a curative to transfuse new victims. This seems to be an anomaly. Edison (talk) 18:21, 26 October 2014 (UTC)

Difference between diffusion of vapors and diffusion of gases

In today's present, it is been obvious that the separate sections of practical physics of thermodynamics thermostatics already had not been scientific perspectives. However, there is been a fundamental difference between the physical phenomena diffusion of vapors and diffusion of gases, so that, is been any significant technical differences between the steam turbine and gas turbine?--Alex Sazonov (talk) 17:03, 26 October 2014 (UTC)

There is no difference between a vapour and a gas, those terms are synonyms. However, technically speaking, steam is not a vapour, but an aerosol. That being said, at the macroscopic scale, steam is equivalent to a vapour, albeit constituted of very large "molecules" (droplets). Since the droplets that from the steam are significantly larger than individual molecules in gas, kinetic friction plays a much more important role when discussing wear and tear on a turbine. The design and operation of the steam turbine would need to compensate for the difference. If steam is heated to above 100°C, it becomes an actual vapour - water vapour. I suspect that most "steam" turbines are actually water vapour turbines. Plasmic Physics (talk) 22:20, 26 October 2014 (UTC)

• More precisely, the word "steam" is used in two different ways. Either it means water vapor or it refers to the aerosol mist formed by water vapor condensing in air. In the context of steam locomotives, steam turbines, and so on, it means water vapor. See here or here, for example.--174.88.134.249 (talk) 04:56, 27 October 2014 (UTC)

The term "steam quality" refers to any of a variety of engineering approximations about the percentage of steam that is gaseous water, compared to the percentage that is suspended droplets of water. Nimur (talk) 22:47, 26 October 2014 (UTC)

Did the vapour and gases been homogeneous substance and uniformity of aggregate physical states of matter, that could be considered as the same physical phenomenon?--Alex Sazonov (talk) 04:13, 27 October 2014 (UTC)

Did the dynamical kinetics of vapour and gases been the homogeneous dynamical kinetics?--Alex Sazonov (talk) 11:51, 27 October 2014 (UTC)

Combining advanced terminology with your level of English is probably not the best choice in this instance. I for one, am completely confused by what you are trying to ask. Try asking with simpler words, then we can try to interpret what you mean to ask. Plasmic Physics (talk) 20:35, 27 October 2014 (UTC)

... and please don't make your words harder to understand by adding been to every sentence? The present tense (third person) of the English verb "to be" is just "is". Dbfirs 00:01, 28 October 2014 (UTC)

Now, now, we're not here to fix others' grammar to the n degree. I'm simply trying to help him, help others to interpret for themselves what he is trying to communicate. Plasmic Physics (talk) 03:21, 28 October 2014 (UTC)

Despite the fact that the physics of thermodynamics and thermostatics studied so, that they had no scientific perspectives. I'm interested in acceptable and unacceptable methods of studying thermodynamics and thermostatics of homogeneous physical environments and their aggregate physical condition.--Alex Sazonov (talk) 09:31, 28 October 2014 (UTC)

October 27

What is the diffrence between Teflon and Plastic"

I've red in the article "Peripheral venous catheter" the next sentence: Modern catheters consist of synthetic polymers such as teflon (hence the often used term 'Venflon' or 'Cathlon' for these venous catheters). In 1950 they consisted of plastic. Is the teflon isn't kind of plastic? 194.114.146.227 (talk) 02:17, 27 October 2014 (UTC)

Well, it's kind of a grey area. "Plastics" are generally considered to be organic molecules - teflon is a carbon-fluorine compound...which is not exactly most people's idea of an "organic" molecule. So I suppose you could argue that teflon is not technically a plastic. However, the word "plastic" and the term "organic" are both somewhat poorly defined, so there is ample room for debate. I agree that the article is a bit vague though - it would have been better if they had specified what kind(s) of plastic were in use in the 1950's. Sadly, the article they reference for this claim is on PubMed, and I don't have an account there to see if the original reference was any more specific. SteveBaker (talk) 03:06, 27 October 2014 (UTC)

Yes, the nomenclature is a bit vague. I've tried a bit, and can't find any digital copy of the 1950 article. Most stuff that old isn't digitized yet (if it ever will be). I found this retrospective from 2008, and this review from 1965 . Both articles just say that the needle was sheathed in "plastic." Apparently the original device was known as the "Massa plastic needle" or "Rochester Plastic needle", that might help someone track down details of the material. SemanticMantis (talk) 14:40, 27 October 2014 (UTC)

UPDATE:- got it: from this article, 2005

So, the originals were PVC, though I suspect several other materials were tried before Teflon became standard. As thanks for finding the info and reference, I hope OP or someone will update the article :) SemanticMantis (talk) 14:40, 27 October 2014 (UTC)

I put in the ref and a link to PVC, but the intro could probably use more re-wording if anyone's interested. SemanticMantis (talk) 15:54, 27 October 2014 (UTC)

Identification of a naval base structure

What is that tunnel looking thing in the foreground with the American flag? I've seen similar structures in other naval base photos as well. — Preceding unsigned comment added by WinterWall (talk • contribs) 03:57, 27 October 2014 (UTC)

You mean the white thing? That's the Arizona Memorial. It sits atop the remnants of the ship which the Japanese sunk in 1941. If you mean the rusty cylindrical thing, that's likely part of a smokestack from the ship. Pearl Harbor is rather shallow. The ship's upper structures were removed and the memorial built over top of it. ←Baseball Bugs carrots→ 04:07, 27 October 2014 (UTC)

Yep, see USS Arizona Memorial. Dismas| 04:10, 27 October 2014 (UTC)

In that aerial photo, you can see the wreckage of the ship in the shallow, clear water there in Pearl Harbor. ←Baseball Bugs carrots→ 05:51, 27 October 2014 (UTC)

Thank you, guys.WinterWall (talk) 04:42, 27 October 2014 (UTC)

Light blend modes

For some reason, I think the sunlight and other light beams use an additive blend mode with the electromagnetic radiation extending it's wavelength nanometres to illuminate light and I don't know where to put the line about the additive blend color on the light, sunlight or something to make it make sense as they have the black parts invisible because of the alpha blending parameter done by electricity being additive and spreads light on the texture shaders to change the brightness and contrast of the objects and the ground to create specularity such as liquid highlights or gloss reflections with the most used reflection method in real life that often uses the camera reflection mapping to convert anything into a reflected image through mirrors. Could somebody give me a clue where to put that line in one of the articles about lights and such illuminating objects with this blending including the X-ray that divides the pixels?--HappyLogolover2011 (talk) 04:12, 27 October 2014 (UTC)

I don't follow your question, but the answer is probably "no." If your understanding of something starts with "for some reason, I think..." then you should not be inserting that thing into an article. We want Misplaced Pages to contain reliable, verifiable, sourced information, not speculations and guesses.

Your question seems to "blend" concepts between the physics of light and computer modeling of illumination. These are two different things, and should not be confused. --Srleffler (talk) 04:40, 27 October 2014 (UTC)

Don't put it anywhere. If you can point us to some published research on the topic, we might be able to give a more favourable answer. Dbfirs 07:32, 27 October 2014 (UTC)

You seem to be using the terminology of computer graphics ("alpha channels", "pixels", "shaders" and "blending") and trying to apply it to the real world. That's a really bad idea! The real world doesn't work remotely like computer graphics do. Graphics are a horrible approximation to the thin slice of reality that humans can actually see, and they don't (generally) simulate anything beyond the red, green and blue frequencies that the human eye is sensitive to, and which common display devices can generate. So we can't answer any of this meaningfully - the question is nonsensical. SteveBaker (talk) 13:40, 27 October 2014 (UTC)

which is re-usable for another mission: Rockets, Space-Craft or Space Flight?

Which is re-usable for another mission: Rockets, Space-Craft or Space Flight? & also tell if space-craft has solar panels so how they reach earth safely & re-usable for next mission? i am going to create a wikipedia article about re-usable space-crafts, that's why i am creating this section.

Ram nareshji (talk) 10:15, 27 October 2014 (UTC)

See our article on Reusable launch systems, which already covers this and a fair bit more. As for the solar panels on the Soyuz, they are attached to the service module - the entirety of which is detached before re-entry and left to burn up in the atmosphere. WegianWarrior (talk) 11:47, 27 October 2014 (UTC)

With Soyuz, not only is the Service Module with the solar panels detached and left to burn up in the atmosphere, but so is the Orbital Module (the round part at the other end). Only the Descent Module, the middle third (29% by length, 43% by mass), is recovered. -- ToE 21:08, 27 October 2014 (UTC)

The RLV article primarily discusses launch systems and not capsules. My understand is that to date no capsule has ever been reflown.

SpaceX has flown six Dragon cargo capsules so far. Their service module with the solar panels is lost, as described above, but the capsule itself is recovered and, according to SpaceX's website, is considered reusable. To date, however, none have been reused. Discussion on the boards suggest that this is because the design has been evolving, and that NASA, at least for now, prefers the reliability of new capsules.

Last month NASA made awards to Boeing and SpaceX for the CCtCap phase of the Commercial Crew Development program. The award is generally described as up to $4.2 billion to Boeing and up to $2.6 billion to SpaceX, but I think that it is more informative to break that down. Only half of the total award, up to $2.5 billion to Boeing and up to $0.9 billion to SpaceX, was for the actual development and certification. The other half, up to $1.7 Billion to each company, was for up to six operational flights of that company's spacecraft carrying a crew of four. This price is based on the current $70.7 Million per seat being paid to Russia. (I assume that this is just an initial price that NASA is agreeing to pay in order to spur development, and that prices are expected to fall later.) Both the Boeing CST-100 and SpaceX's Dragon V2 are described as reusable, but I have not yet heard whether NASA will be accepting rides in used capsules or will be insisting on new. I don't believe that details of the awards (such as a list milestones for the development phase or requirements for the operational flights) have been publicly released yet. -- ToE 13:17, 27 October 2014 (UTC)

For the solar panels part: On the space shuttle, the solar panels were built inside the two cargo bay doors which were closed and locked for re-entry. For every other spacecraft that's returned to earth safely, there either weren't any large solar panels (Apollo era and earlier) - or they were jettisoned before re-entry.

One question though: If you know so little about it, why are you even considering writing a Misplaced Pages article about it?!

SteveBaker (talk) 13:35, 27 October 2014 (UTC)

Solar power was not used on the Space Shuttle orbiters. Per Space Shuttle orbiter#Electrical power, "Electrical power for the orbiter's subsystems was provided by a set of three hydrogen-oxygen fuel cells ...". Hydrazine burning auxiliary power units (APU) were used to generate hydraulic power during ascent and during reentry and landing. They would open the cargo bay doors shortly after reaching orbit, not to expose solar panels, but to expose heat rejection units which radiated excess heat from the onboard systems. -- ToE 15:28, 27 October 2014 (UTC)

Here is a NASA page detailing the Shuttle's Active Thermal Control System. There were two radiator panes on each side of an orbiter's cargo bay, attached to the doors. The aft two panels were fixed to the doors and could radiate only in only one direction, but the forward radiator panels could, if demanded by the thermal loads, deploy away from the doors and radiate on both sides. In File:Sunrise over Spacelab.jpg from STS-90, the deployed forward port radiator panel is clearly visible. -- ToE 15:53, 27 October 2014 (UTC)

X-37B, USAF's mini-shuttle, is a long duration spacecraft which does use solar panels. I don't now how accurate this artist's conception is, but if that is representative of their solar array, they would have to refurl it to stow it in the payload bay. I hope they have a means of jettisoning the array in case the furling mechanism jams. -- ToE 17:04, 27 October 2014 (UTC)

Lymphogranulomatosis

I encountered this word in a WWII-era memoir. Here in the English Misplaced Pages it doesn't redirect to anything, while a search here brings up various associations with Hodgkin's lymphoma. Are they exactly synonymous? What would be a suitable redirect for lymphogranulomatosis? -- Deborahjay (talk) 12:40, 27 October 2014 (UTC)

Merriam Webster defines this term as: "the development of benign or malignant nodular swellings of lymph nodes in various parts of the body; also : a condition characterized by these" - so I'd guess that any such swelling would be described this way - and I presume that Hodgkin's is just one reason that this could happen. So I think a redirect would be a very bad idea. We wouldn't want everyone with swollen lymph nodes to automatically assume that they had Hodgkin's disease. It probably needs an article of it's own...with cross-links between it and Hodgkin's lymphoma. SteveBaker (talk) 13:45, 27 October 2014 (UTC)

I just checked some other dictionaries and one said "an infectious granuloma of the lymphatic system. The term is used to identify several inflammatory, granulomatous or sarcomatous disorders, such as Hodgkin's disease, lymphadenoma, lymphadenoma venereum, and sarcoidosis." - so it would DEFINITELY be incorrect to redirect Lymphogranulomatosis to Hodgkin's lymphoma. SteveBaker (talk) 13:48, 27 October 2014 (UTC)

Agreed. Note Lymphogranuloma venereum, which is among the most common conditions with which this term is associated. -- Scray (talk) 00:37, 28 October 2014 (UTC)

We could create a list article, giving SteveBaker's definition of Lymphogranulomatosis, and a list of the conditions that cause it. CS Miller (talk) 10:03, 28 October 2014 (UTC)

Why do people do so little to fight volcanoes?

My understanding is that people in Iceland have frequently fought lava flows, directing them away from inhabited areas. So why do people in Hawaii seem to leave it up to the lava flow to decide which way to go, even where there is no clear indication of which way it will choose? Even beyond this, why don't people drill into volcanoes and try to make artificial vents for lava to be channeled away to uninhabited areas, or even take on magma reservoirs proactively and cool them with lots of water, making use of turbines and condensers to cool and recycle it while not coincidentally making a fortune in geothermal power? I feel like there's this huge assumption of helplessness in the face of a phenomenon that really isn't even very powerful by comparison to the thermal mass humans move in ordinary waterworks. Wnt (talk) 22:04, 27 October 2014 (UTC)

This USGS page describes the Icelandic attempts to cool and divert lava flows, but also mentions attempts in other places, including Hawaii. This page describes some of the issues with doing things the Icelandic way in Hawaii, specifically the availability of seawater, as very large volumes are required. Mikenorton (talk) 22:20, 27 October 2014 (UTC)

That's a good question. In the header, I mean. The followup is definitely good, too, but the question alone really made me think. Thanks! All I can offer in return is "Because they're too hot." Sorry. InedibleHulk (talk) 23:01, October 27, 2014 (UTC)

Which volcanoes? There may be things that can be done in some cases to ameliorate the effects of some volcanoes. But the word "volcano" encompasses a wide range of very disparate geological phenomena, and the fact that something could maybe be done for some kinds of volcanoes doesn't mean that anything could be done for others. The Hawaiian type of volcanoes are a peculiar type which isn't necessarily like any other type. Shield volcano covers some of the information on the Hawaiian type: You'll note that the text says "Most of what is currently known about shield volcanic eruptive character has been gleaned from studies done on the volcanoes of Hawaiʻi island, by far the most intensively studied of all shields due to their scientific accessibility; the island lends its name to the slow-moving, effusive eruptions typical of shield volcanism, known as Hawaiian eruptions." You'd have to believe that if Kīlauea is the possibly most studied volcano on earth, someone would have come up with some way to stop ameliorate its effects. It isn't as simple as you seem to make it out to be, as though thousands of vulcanologists had been studying Kīlauea for decades, and to a person they said "You know, we could totally fix this thing, but man, fuck all those Hawaiians" That isn't how it works. The scale and scope of the situation likely makes it beyond the means to fix. --Jayron32 23:22, 27 October 2014 (UTC)

I was wondering about this myself, watching what's going on in Hawaii. I know the Icelanders were successful at least once using water to freeze a dike to divert the flow away from a town. I'd look into the money and political aspect of it, both, would it threaten other towns if diverted, and is there environmental opposition to "interfering" with nature, or worse, with Pele. ABC tonight showed the authorities were quite happy to build new roads at an emergency pace and build protective barriers to protect electric poles. This shoes that the "all is lost" attitude is not being applied equally. It does not seem irrelevant that the activist native community is a large part of the constituency of the ruling party in the state. μηδείς (talk) 01:34, 28 October 2014 (UTC)

Again, in this case we're comparing mountains to molehills, almost literally. The Icelandic situation you are talking about is likely the volcano Eldfell on the island Heimaey. Eldfell was a smallish cinder cone which erupted over a few months and put out a TINY fraction of the Lava that Kīlauea puts out. Eldfell is 200 meters tall, and the size of the footprint of that lava flow is probably 1.5 square kilometers. Kīlauea has been erupting more-or-less nonstop for 30 years, it's 1200+ meters tall, and part of a single volcano (including the neighboring calderas of Mauna Loa and Mauna Kea) which is many orders of magnitude larger than the Heimaey. Look, Heimaey is about as big as Manhattan south of Central Park. The Big Island of Hawaii (which is basically all the single volcano) is a tad smaller than the state of Connecticut. The ability to save the fishing village on Heimaey in no way relates to the ability to do the same on the Big Island of Hawaii; the scale difference is like swatting a fly versus swatting an eagle. --Jayron32 12:15, 28 October 2014 (UTC)

Mikenorton's answer is really helpful; those links might be enough to seed an article on diversion of lava flows. The sources explain that pumping seawater to divert lava is easiest very near the ocean (i.e. to save a harbor) rather than far away, and of course Hawaii has more internal development by far than Iceland. That said, I still can't believe that the sort of people who you see in TV shows about gold digging in Alaska couldn't manage to use half a dozen earth movers to make a trench sufficient to accommodate something like this, backed up by a strong dike with the overflow, at a rate fully equal to the 10-15 yards per hour that the lava flows. Based on the scale of the trees in the foreground, it's just not all that wide and not all that deep either. (Obviously, I'd expect them to work in a number of separate zones for maximum efficiency, and plan completion well before the magma enters!) Wnt (talk) 12:07, 28 October 2014 (UTC)

highest price of oil per barrel

what is the highest price of oil per 'barrel' (unit volume) if we take 'oil' to mean the verified oevre in oil of one painter. For example, all of the verified Van Gogh oil prints that are on the market, could be divided by their volume and multiplied by the volume of a barrel of oil, to give the price per barrel of 'van gogh' oil. By this metric which verified painter would have highest price per barrel, and who would it be? 212.96.61.236 (talk) 23:33, 27 October 2014 (UTC)

this is probably unquantifiable or at least you'll never get a definitive response because many works by the most prominent oily artists go unsold and estimates for those paintings cannot be reliably made...i think that da vinci might be up there though, since he had like 15 paintings with oil or something and they're all widely known and sell for bout a hundred million quid ? also minimalist painters who use oil might be up there too ~Helicopter Llama~ 00:25, 28 October 2014 (UTC)

Infinite, for any painting that doesn't use oil. The question doesn't make sense because a painting consists of much more than just oil--there's also paper, wood, pigments, dirt, hairs from the paintbrush, etc. The thing that has value is the creativity and authorship behind the painting, not the painting's physical components. --50.46.159.94 (talk) 07:43, 28 October 2014 (UTC)

October 28

Space blanket - contra indication

I've red in the article "space blanket" in French that the contra indication of "space blanket" is a storm. I don't understand why is that. Before, I thought that the place to use it, it's only in storms and things like this. I'm wonder. 149.78.224.210 (talk) 00:33, 28 October 2014 (UTC)

If I'm reading your question correctly, you're wondering why a space blanket shouldn't be used during a storm. If that's so, it's due to the blanket being coated with a thin film of metal. As metals conduct electricity, it would be a likely place for lightning to strike. Dismas| 01:40, 28 October 2014 (UTC)

Not the way lightning works. It just traversed miles of air and a tiny bit of mylar isn't going to change it. Pointy or height is what causes high electric fields, not metal. --DHeyward (talk) 04:14, 28 October 2014 (UTC)

Several feet (a couple of meters) of conductive material may not make a difference to where the lightning bolt touches the ground, but it'll make a difference to where the electricity conducts to when it does. Not likely to be a big deal—unless those few feet are the difference between being seriously shocked and not. --174.88.134.249 (talk) 05:28, 28 October 2014 (UTC)

Is there a reliable source for that contra-indication? I would have expected the blanket to act like a Faraday cage.--Shantavira| 10:42, 28 October 2014 (UTC)

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