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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)[reply]

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)[reply]

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)[reply]

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)[reply]

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)[reply]

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)[reply]

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)[reply]

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)[reply]

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

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)[reply]

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)[reply]

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)[reply]

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)[reply]

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)[reply]

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)[reply]

(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)[reply]

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)[reply]

Thanks, all. Joseph A. Spadaro (talk) 18:45, 28 October 2014 (UTC)[reply]

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)[reply]

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)[reply]

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)[reply]

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)[reply]

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

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

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

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

[1] 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 [2] [3] 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)[reply]

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

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)[reply]

If you get nipped, you can get even by catching it and turning it into Crawfish Étouffée. ←Baseball Bugs ^{What's up, Doc?} carrots→ 20:18, 25 October 2014 (UTC)[reply]

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)[reply]

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." [4] 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)[reply]

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)[reply]

In the UK:

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

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)[reply]

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.[3] It is known to damage oyster fisheries.[4] 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)[reply]

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)[reply]

@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:

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)[reply]

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)[reply]

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)[reply]

I know it isn't an answer you're looking for, but Ugly American seems to fit.-27.252.73.107 (talk) 20:43, 28 October 2014 (UTC)[reply]

Think you'll find that the scientific name for these critters is Homo Americanus. Someone has even written a book about them and their social behaviors etc. [5]. ;-)--Aspro (talk) 21:48, 28 October 2014 (UTC)[reply]

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.

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)[reply]

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)[reply]

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! (^{hurt me} / _{more pain}) 07:18, 28 October 2014 (UTC)[reply]

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)[reply]

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 [6]. Wnt (talk) 11:37, 25 October 2014 (UTC)[reply]

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)[reply]

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-imidazo[1,2-a]pyridine, which belongs to the Imidazo[1,2-a]pyridines, 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-imidazo[1,2-a]pyridine'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-imidazo[1,2-a]pyridine, 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)[reply]

Luminol is not fairly toxic[7] and NMRs are used in characterization, not synthesis. Rmhermen (talk) 17:33, 26 October 2014 (UTC)[reply]

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)[reply]

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)[reply]

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)[reply]

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)[reply]

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)[reply]

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)[reply]

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)[reply]

What is the different between Atom and element?

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

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)[reply]

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)[reply]

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)[reply]

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)[reply]

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)[reply]

I strongly disagree. An "element" isn't a thing - it's a kind of description, like "color" or "flavor". A better analogy is that I have a ball in my hand that is red and red is a color. I have a diamond that is carbon and carbon is an element. A brick is the basic building block of a wall that is brown - and an atom is the basic building block of a chunk of diamond that is carbon. Both a single atom and the chunk of diamond are described as being carbon - which is a particular element, but the atom and the lump of matter are not "elements" - just like bricks and walls aren't "colors".

"Elements" are descriptions of atoms - specifically, the number of protons in the atom, just as "Colors" are descriptions of materials - specifically, the frequencies of light that they reflect. Saying "This diamond is made of the element carbon" is like saying "This ball is of the color red"...one is a description of the number of protons in the atoms, the other is a description of the reflectivity of those atoms.

The word 'element' is like the word 'color', and the word "carbon" is like the word "red".

SteveBaker (talk) 14:19, 29 October 2014 (UTC)[reply]

I disagree stronger ;-). We've had elements long before we knew about the structure of atoms, or the existence of protons. Now we know that elements consist of atoms with the same electron configuration (and only by implication the same number of protons!). But that is not elementary about elements. An element is a substance that cannot, by any chemical means, be broken down into simpler substances. An atom is the smallest individual unit of an element. --Stephan Schulz (talk) 23:06, 29 October 2014 (UTC)[reply]

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)[reply]

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 ^{What's up, Doc?} carrots→ 01:36, 26 October 2014 (UTC)[reply]

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)[reply]

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 ^{What's up, Doc?} carrots→ 04:08, 26 October 2014 (UTC)[reply]

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) [reply]

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

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)[reply]

Sunspot cycles are among the elements used by the Old Farmers Almanac. ←Baseball Bugs ^{What's up, Doc?} carrots→ 15:26, 26 October 2014 (UTC)[reply]

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)[reply]

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)[reply]

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)[reply]