Wikipedia:Reference desk/Archives/Science/2013 March 13

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March 13

Vaccinations and antibiotics

I have a friend who said that vaccinations make an individual less reactive to antibiotics. It sounds like bullshit, but I just want to make sure. Btw this isn't medical advice, just curious. ScienceApe (talk) 02:01, 13 March 2013 (UTC)

They speak of making vaccinations for things such as nicotine or heroine. It would depend entirely what substances to which the vaccine caused the immune system to become sensitive. It would never be a case of "any vaccination will make you less sensitive to antibiotics." It would be a matter of a particular vaccine making you less sensitive to a particular antibiotic for a particular reason. The only exception would be if, somehow, the substances in which the vaccine is contained (whatever it's called, serum?) made you less sensitive to antibiotics. B^e——C_ritical 03:07, 13 March 2013 (UTC)

Do you have a link to someone who has proposed the nicotene and heroine vaccine? Is it viable in the near future? It sounds amazing. 80.254.147.164 (talk) 09:54, 13 March 2013 (UTC)

There's some information available at the "NicVAX" and "TA-NIC" articles regarding a nicotine vaccine. Gabbe (talk) 12:36, 13 March 2013 (UTC)

• Also, we have a little info on a cocaine vaccine candidate, TA-CD. -- Scray (talk) 16:00, 13 March 2013 (UTC)

• Vaccines that prevent bacterial infections, like the conjugated pneumococcal vaccine, generally reduce occurrence and severity of the infection for which they are licensed. I am not aware of direct study of this phenomenon (it would be difficult), but current knowledge suggests that in those people for whom prevention is not complete, vaccine-related reduced severity is likely due to reduced organism burden. Reduced organism burden favors antibiotic efficacy (see Eagle effect - a very unfortunate redlinknow a bluelink - c'mon over and help beef it up!; see PMID 3292661 and description in a recent (2008) textbook). So, available data strongly suggest that antibacterial vaccines would, if anything, have a beneficial effect on responsiveness to antibacterial therapy. Becritical's speculation on what might happen if someone used an antibacterial like a vaccine, to raise antibodies to the drug itself, is clever but I'm not aware of evidence suggesting that such a phenomenon has been observed for an antibiotic. People with IgE antibodies to penicillin respond quite well once desensitized (PMID 22187514 and PMID 3040836), even though desensitization does not reduce the level of the antibodies. -- Scray (talk) 05:59, 13 March 2013 (UTC)
• Could you explain what you mean by "less reactive"? I ask because it's a common misconception that people become immune to antibiotics and maybe that's what your friend mean. If that's the case the answer is no. As our articles Antibacterial and Antibiotic resistance explain, microorganisms can become immune, but that process has nothing to do with vaccinations. Sjö (talk) 06:15, 13 March 2013 (UTC)

Fear of immunizations is common and accompanied by a seemingly endless list of unsubstantiatable rationalizations to justify the refusal. There is no evidence that being immunized changes ones' reaction to an antibiotic or any other drug. Vaccines work by inducing the person's immune system to add a new antigen (usually a cell wall protein from the bacterium or virus to which we wish to induce immunity) to its recognizable "enemy list", so that it is readier to quell infection when the person next encounters that microbe. Immunization does not affect drug metabolism, nor does it change the population of microbes that are part of our bodies. alteripse (talk) 09:47, 13 March 2013 (UTC)

Is the dust produced from ultrasonic humidifiers bad for the lungs?

We have well water with a certain amount of Alkali in it. I don't know the exact composition, although I think it is mostly sodium carbonate with small amounts of a substance which tastes like table salt. After using the well water overnight in the humidifier, there is a very fine dust that can be seen when sunlight streams into the room. It does not cause any irritation. But I'm guessing it is ultra small particles, possibly crystals, which will enter the deep lungs. Is this a health hazard? Reading this, it seems as if the lungs clean out normal particles, but these may not be "normal." B^e——C_ritical 03:08, 13 March 2013 (UTC)

If the dust is sodium carbonate, it should dissolve in the lungs' mucous lining with no harmful effect. 24.23.196.85 (talk) 03:07, 13 March 2013 (UTC)

Thanks, I hope you're right (: B^e——C_ritical 05:28, 13 March 2013 (UTC)

I wouldn't recommend that. The manufacturers instructions will tell you to use distilled water. Using non-distilled water gets dust around the adjacent area and can be an eye irritant. If you directly inhaled it all day long, it might also be a lung irritant, too, but most of the dust probably settles out before you breath it in. If you want to use well water, you need to get the type of humidifier which heats the water. These use a lot more electricity, but, in the winter, when you would normally use a humidifier (here, at least), the extra heat is welcome, and reduces the need for heat from other sources. (Not so if you happen to live in a desert, though.) The heater type does require that you dump out the water occasionally, or minerals will come out of solution and form scale. StuRat (talk) 04:22, 13 March 2013 (UTC)

The instructions that came with it say "3. Remove tank by holding .....bring tank to sink... and fill...with water, ideally distilled water." It sounds like they made it to use tap water, so they must think they can't get sued to lung damage. It also talks about how to clean the "scale" and "mineral" residue from the tank with vinegar. B^e——C_ritical 04:38, 13 March 2013 (UTC)

I'd think tap water would be even worse than well water, in that chlorine or other disinfectants will then be turned into a gas. Like cigarettes, if you develop lung problems, it would be difficult to prove in court that it was the humidifier that did it. And, since they do say distilled water is recommended, they could also argue that you used it "in a manner inconsistent with manufacturer recommendations". StuRat (talk) 04:50, 13 March 2013 (UTC)

Actually, while the chlorine would indeed turn into a gas, its concentration will be negligible -- so you wouldn't develop lung problems just from using tap water in the humidifier. Remember, the dose makes the poison! 24.23.196.85 (talk) 00:28, 14 March 2013 (UTC)

I think it still does damage to the lungs at a low dose, just at a lower rate. StuRat (talk) 03:32, 15 March 2013 (UTC)

BTW, I'm guessing you didn't know you needed to use distilled water when you bought it ? I bought one once, tried it both ways, and decided I was neither willing to pay for gallons of distilled water per week or to put up with adding dust to the air, so returned it. They seem like quite a rip-off, to me. I got a proper humidifier, instead. StuRat (talk) 04:53, 13 March 2013 (UTC)

I was well aware that it would cause dust, however online reviews say that the dust settles around the humidifier, which I thought was acceptable. Chlorine would be safe, I think, but an irritant. The thing is I love it, much more so than I would one of those ones that use heat, or just use a wet filter thingy. It puts out wonderful cold steam. But since I would use it winter and summer for years, I do need to try and figure out if it is actually a health threat. So let me see if I can organize thought:

• I guess it could be harmful and they would feel safe from the law, you're right.
• I don't care if it's an irritant, since it doesn't seem to actually irritate- either eyes or lungs, and the other person is extraordinarily sensitive to such things. In fact it cured their cough, as nothing else has.
• I don't think the dust settles around the humidifier- it spreads all over the room.
• The dust I saw seemed as fine as smoke
• I hope the IP was right that the substance is harmless, but I don't know for sure.
• So although helpful, I'm not sure if I have my answer yet. B^e——C_ritical 05:28, 13 March 2013 (UTC)

• Note that, even if it's not an irritant to you, it may well be to others. Of course, dry air is also an irritant, so this humidifier may improve conditions for some, and worsen them for others. Also, do you live in a desert ? Otherwise, why would you need it in summer ? Most people need a dehumidifier in summer. As far as a health threat, I'd put it up there with other air pollution. That is, a minor threat, except for those who are more sensitive, such as those with lung diseases, like asthma. StuRat (talk) 05:33, 13 March 2013 (UTC)

Yes, a desert. And it cured the cough of someone with minor asthma and didn't seem to be any irritant, but this person can breathe a lot of smoke so maybe they aren't as sensitive to everything... And actually a little air pollution would be worth the risk. I just don't want it to be like silica dust, and there is all sorts of scare over nanoparticles, which this definitely is. Hope you're right (; B^e——C_ritical 05:51, 13 March 2013 (UTC)

For a desert climate, you might consider using a swamp cooler is summer. They produce humidity as a byproduct, so hopefully would eliminate the need for the ultrasonic humidifier. StuRat (talk) 07:05, 13 March 2013 (UTC)

Yes, we already do that. But considering our humidity level, it doesn't really do the complete job, and you can't leave it on all night without getting too cold. It only gives a certain level of humidity, things are still dry. B^e——C_ritical 18:34, 13 March 2013 (UTC)

An easy test for the origin of the dust: Take a pinch of it and put it in water -- if it dissolves readily, then it comes from the mineral salts in the water and is harmless; if it doesn't, then it comes from the suspended soil particles in the water, and may or may not be harmful. 24.23.196.85 (talk) 04:38, 14 March 2013 (UTC)

S-phone

Could an agent in the field swap an S-Phone's transmission and reception frequencies simply by switching the vacuum tubes between the two circuits? Or was it something that could be done only in the workshop? Thanks in advance! 24.23.196.85 (talk) 03:04, 13 March 2013 (UTC)

I only have a rudimentary understanding of radios, but having a guess, rx and tx frequency are not set by the tubes, but by a tuner circuit, at that time, probably little more then a capacitor and an inductor. Having no idea how the S-Phone was designed, I'd say it'll be hard to tell whether they could be swapped by someone in the field. I suspect it would not be impossible given a little skill and a soldering iron. Unless they were encased in resin or something so the factory settings could not be fiddled with, which is also not impossible.. Vespine (talk) 05:18, 13 March 2013 (UTC)

The frequency of the S pahone transmitter and receiver circuits was likely controlled by crystals. Here is a 1944 article which says crystals were used in many WW2 field radios. It says "Practically all fixed-frequency transmitters and receivers employ them.." If the freqs were crystal controlled, then changing the crystals would change the frequencies. I could not find a circuit diagram or detailed description of the S phone, but turning a dial back and forth searching for a transmitting frequency while you're flying over enemy territory at low altitude at night does not sound like a good approach, when crystal frequency control was the rule for battleground communications. Edison (talk) 22:12, 13 March 2013 (UTC)

Ok, that's interesting! Good find. Vespine (talk) 00:23, 14 March 2013 (UTC)

Thanks! So what you're saying is, the agent could swap the frequencies by switching components between the transmitter and receiver circuit if she knows exactly what she's doing, right? 24.23.196.85 (talk) 00:25, 14 March 2013 (UTC)

The process isn't difficult. You just have to have the right parts! If you ever played with a cheap toy CB radio, you might be familiar with these things - you just get the right part, plug it in the socket, and presto - your toy radio now operates on a different channel! Such radios don't even have a "tuning knob" at all! Nimur (talk) 01:20, 14 March 2013 (UTC)

Identification of mushrooms in potting soil

I'm trying to identify the following mushrooms:

They seem related to Coprinellus micaceus, but I don't know enough about mushrooms to make any positive identification.

These are growing in the southwestern U.S.A, however the soil could have come from anywhere. They also seem to die very quickly when not watered.

Additionally, if anyone knows additional information, such as if they are potentially poisonous to terrarium creatures such as frogs, and how best to get rid of them (other than reducing humidity), that would be very helpful. Thanks in advance!! WDavis1911 (talk) 03:37, 13 March 2013 (UTC)

You should try asking at http://en.wikipedia.org/wiki/Wikipedia_talk:WikiProject_Fungi Richerman (talk) 11:47, 13 March 2013 (UTC)

I apologize, I'm going to offer information that you didn't ask for :) First, consider that fungi play a vital role in all terrestrial ecosystems; they provide pathways for nutrient cycling between plants, animals, etc. So they may well be good for your terrarium plants. Note that the fruiting body only emerges after much mycelial growth, so popping the tops off will not necessarily prevent more from coming up. However, they will stop coming up once the fungus has digested all its available food (and converted it into plant food). I also doubt that the frogs would eat the mushrooms. They aren't nearly as tasty as the flies, crickets/whatever you feed the frogs. (On an aesthetic note, I think those are some good looking 'shrooms, and they would enhance the beauty of any terrarium). Finally, people do use fungicides, including sulphur. But my opinion is that those compounds would be more dangerous to your terrarium than the mushrooms themselves. SemanticMantis (talk) 19:37, 13 March 2013 (UTC)

Some topics

Can anyone give me some topics that connect maths with geology or geography? 117.226.246.138 (talk) 07:54, 13 March 2013 (UTC)

See mathematical geosciences. i'm sure someone will help you more. IBE (talk) 08:04, 13 March 2013 (UTC)

How about GPS units ? They use heavy math to determine your location, and geologists and geographers use them to note the locations of various natural features. StuRat (talk) 08:12, 13 March 2013 (UTC)

Geophysics is quite maths intensive. Graeme Bartlett (talk) 09:04, 13 March 2013 (UTC)

And of course, geotechnical engineering! There are numerous areas of study in civil engineering, petroleum engineering, hydrology, and geophysics that combine mathematical modeling and geological knowledge for productive or academic purposes. There's also geographic information systems - known everywhere as "GIS" - which combines mathematics, computing, and geography. Nimur (talk) 01:28, 14 March 2013 (UTC)

Geodesy. Pfly (talk) 06:10, 14 March 2013 (UTC)

Pictures

Which of these two pictures is correct? 1, 2. The first one says that first humans were 2 million years ago, and the second one says that the first hominids were 2 million years ago. — Preceding unsigned comment added by Th4n3r (talk • contribs) 09:32, 13 March 2013 (UTC)

I think the first is correct, following modern terminology. A "human" is any members of the genus Homo, of which the only living species is Homo sapiens. The earliest humans were (possibly) the species Homo habilis which lived in Africa approximately 2 million years ago. A "hominid" is any member of the family Hominidae (great apes) which includes chimpanzees, bonobos and gorillas as well as humans. The ancestry of the Hominidae family goes back much further than humans, approximately 14 or 15 million years. However, the second diagram may simply be out-dated, as historically "hominid" was used to refer to the genus Homo, and the other great apes were placed in a separate family called Pongidae. Gandalf61 (talk) 10:30, 13 March 2013 (UTC)

"Neanderthals' large eyes 'caused their demise'"

In the BBC coverage of this story ([1]) it reports that the slightly smaller brain meant that Neanderthals became extinct, while modern man survived, because they had to live in small groups and couldn't adapt to the Ice Age. If that's the case, wouldn't every primate species with smaller brains than ours have died out? --Dweller (talk) 11:46, 13 March 2013 (UTC)

Not necessarily. Neanderthals and humans may have been competing for the same Ecological niche which is why the Neanderthals didn't survive in competition with the humans. Humans would not have necessarily been in direct ecological competition with every other primate. --Jayron32 11:58, 13 March 2013 (UTC)

That explanation sounds odd to me. First, Neanderthals are known to have had brains slightly larger than ours. Second, they are also known to have been better adapted to cold weather than we are. Third, What does large eye's got to do with anything? Dauto (talk) 13:47, 13 March 2013 (UTC)

The reason given by the researchers is that because Neanderthals needed to cope with low light conditions in Europe, they evolved large eyes and a correspondingly large visual cortex: and that this happened at the expense of developing social skills. Personally I think it's odd too. --TammyMoet (talk) 13:54, 13 March 2013 (UTC)

I don't think that explanation passes the smell test. Dauto (talk) 14:03, 13 March 2013 (UTC)

I think one would have to treat this as a Just-so story for the moment, especially when the second last paragraph talks about the same visual area effect with modern humans but says the effect on other cognitive abilities has not been seen. Dmcq (talk) 14:22, 13 March 2013 (UTC)

I think you need to invoke what Jayron says above about competition. So, while Neanderthals could later have gone on to evolve their brains to improve social behavior, if humans were around at that time, natural selection would lead to the selection of our ancestors who already had these social skills. Count Iblis (talk) 15:07, 13 March 2013 (UTC)

The article at hand points to some alternative explanations to the BBC's. OsmanRF34 (talk) 15:08, 13 March 2013 (UTC)

The headline of the BBC report is typical bad BBC science reporting. If you had a Neantherdal,and a modern human side by side you could identify a list of differences and then theorise as to which one was 'the' crucial one that caused the extinction of N. This researcher has been investigating eye size and postulates a mechanism by which this could be the crucial difference. But they can't prove it, it is just a hypothesis. The BBC headline implies that the hypothesis has been proved. That's not science, it is journalism. Greglocock (talk) 23:57, 13 March 2013 (UTC)

Isn't it the case that some Neanderthal DNA has turned up in the modern human population? ←Baseball Bugs ^{What's up, Doc?} carrots→ 03:32, 14 March 2013 (UTC)

Yes, we're not totally extinct! Dbfirs 08:34, 14 March 2013 (UTC)

One of the science-oriented TV channels, possibly the Discovery Channel, said something about Neanderthal DNA being in all the major races except African, which implied some intermarriage (or inter-mating) after dispersal to Europe and before dispersal eastward. ←Baseball Bugs ^{What's up, Doc?} carrots→ 12:09, 14 March 2013 (UTC)

Resolved

 – thank you, chaps, it's a case of bad reporting. --Dweller (talk) 16:00, 14 March 2013 (UTC)

What if we didn't react to the Common Cold?

It seems like most of the symptoms of the common cold are caused our immune system's reaction to the viruses. The fever, congestion, aches, tiredness etc is caused by our bodies fighting it. What if our immune systems didn't fight the virus? Are the viruses severe enough to cause us any harm? Could scientists theoretically "cure" the common cold by instead teaching immune systems not to react to it? Thanks! — Sam 63.138.152.157 (talk) 12:21, 13 March 2013 (UTC)

Without any immune reaction the virus would multiply unchecked and eventually might start killing the cells they infected leading to death. Dauto (talk) 13:43, 13 March 2013 (UTC)

Colds do kill people with compromised immune systems, so your premise falls anyway. --TammyMoet (talk) 13:52, 13 March 2013 (UTC)

Agreed, and when we say a disease "isn't that dangerous", what we mean by that is that our immune system is able to deal with it before it kills us. Pretty much any infectious agent would eventually kill us, if we had no immune response at all. See the cases of the bubble boys. StuRat (talk) 14:56, 13 March 2013 (UTC)

• Examples: PMID 10530441 (adult blood and marrow transplant recipients), PMID 17704788 (adult stem cell transplant recipients), PMID 23092635 (kids in an orphanage in Vietnam, possibly malnourished). Better to have sniffles (a raging immunological battle in the upper airways) and tiredness than pneumonia. -- Scray (talk) 15:56, 13 March 2013 (UTC)

So, why don't animals get the Common Cold? Count Iblis (talk) 16:08, 13 March 2013 (UTC)

They can't contract human variations of the cold, and most house-pets don't come into much contact with other members of their species.

"Outdoors cats" can absolutely catch feline cold viruses from other cats. (The symptoms are about what you'd expect.) I assume it's the same for dogs and such.

APL (talk) 16:16, 13 March 2013 (UTC)

Yeah, dogs can definitely catch cold. I've seen dogs with basically the same symptoms as humans, so that they're sniffling, having runny noses, sneezing, etc., for a while before getting better on their own a few days later. —SeekingAnswers (reply) —Preceding undated comment added 21:03, 13 March 2013 (UTC)

Many different viruses cause the Common Cold. Viruses have various host restriction factors (an unfortunate redlink that should be remedied), and these are often targets of research because they reveal crucial steps in a virus life cycle. In the case of HIV, host restriction factors include APOBEC3 and TRIM5alpha -- Scray (talk) 23:04, 13 March 2013 (UTC)

And in reference to the OP's initial premise, the symptoms of a number of infections are a result of the immune response rather than to the otherwise dangerous effects of the etiologic agent, such as periodontitis. In fact, there is (limited) research to support the use of tumor necrosis factor inhibition for both this and other diseases. DRosenbach ^{(Talk | Contribs)} 00:49, 14 March 2013 (UTC)

quadrupole of CO2, N2 etc

It is said that CO₂ has a large quadrupole and N₂ has a smaller one. I guess this term is referring to nonspherical electronic or charge distribution, but alternative explanations would be welcome. Maybe we could upgrade quadrupole, where I found the image to the right.

Contour plot of the equipotential surfaces of an electric quadrupole field.

So what I would like to do is mentally map the coordinates of CO₂ or N₂ onto such an image. Even better would be a qualitative explanation about the magnitude of the quadrupole (moment?). Apparently the magnitude of the quadrupole relates to the absorption (or absorption, I can never get these straight) of the gases onto surfaces, which is what I am also after.--Smokefoot (talk) 13:23, 13 March 2013 (UTC)

Both CO₂ and N₂ are linear molecules. By symmetry the molecules must be aligned diagonally with the pictures. Given that Oxygen is more electronegative than Carbon, it's clear that the two Oxygen atoms will be located at the corners that have negative charges and the Carbon atom will be at the center. Given that there is no electronegativity imbalance in the N₂ there will be a much smaller charge separation and a smaller quadrupole to go along with it. I have no idea which diagonal the Nitrogen atoms will align with. Dauto (talk) 13:38, 13 March 2013 (UTC)

Guaiphenesin

Can guaiphenesin make urine smell phenolic? --TammyMoet (talk) 13:55, 13 March 2013 (UTC)

It's apparently excreted unchanged in the urine. I have no idea if guaiphenisin itself smells phenolic. μηδείς (talk) 16:49, 13 March 2013 (UTC)

To complete this question, our article gives a link to guaiacol, and the article there says that it gives the flavour to smoked food. So the answer may be yes. --TammyMoet (talk) 12:48, 14 March 2013 (UTC)

Toxicity of Bakelite in my old camera collection

I have a collection of old cameras. Some of them are made of Bakelite. A few of them have some damage. I've read conflicting reports on the toxicity of Bakelite. Some websites claim being near it is a death-sentence, and that even having it near you can cause problems. Our article doesn't mention it's toxicity and I am confused about how dangerous it is to keep chipped Bakelite products in my living room. Can anybody shed some light on this for me? 217.158.236.14 (talk) 15:50, 13 March 2013 (UTC)

Here is a link to a MSDS for bakelite: [2]. You can read through yourself and see the safety precautions. It seems that it is not a good idea to inhale powdered bakelite, or to melt it and inhale the fumes. Other than that, I think it is reasonable to have old bakelite cameras in your living room. SemanticMantis (talk) 16:51, 13 March 2013 (UTC)

Oh, and I should mention that that MSDS is for the use of bakelite as a hot mounting compound, sold by this company [3]. So that's why they say not to get it on your skin (i.e. in the state of hot melted plastic). I have not yet found a MSDS for already cast bakelite products. But I have found a lot of unreliable looking scare pages, which I am personally ignoring until we hear more answers here. SemanticMantis (talk) 16:57, 13 March 2013 (UTC)

Thank you, SemanticMantis. It is these scare pages which I have read. I hope somebody can offer some further advice. Thanks for posting the link above, as well. 217.158.236.14 (talk) 17:14, 13 March 2013 (UTC)

Bakelite is a hard plastic (thermoset plastic). Unlike soft plastics (thermoplastics), hard plastics like Bakelite do not tend to leach out plasticizers. That would be the main health concern with a plastic in it's solid form. However, as previously noted, when heated, hard plastics do give off fumes. Specifically, they give off smoke, while soft plastics melt. And I also agree that inhaling powdered plastics is not a good idea. So, as long as you don't put it in an oven, you should be OK. I suppose there is some risk that you could inhale fumes from it if your house catches fire, but that seems like an acceptable risk, to me. You decide for yourself. (Note that a home which doesn't give of any toxic fumes while on fire would basically be a home devoid of all flammable materials, meaning concrete, glass, and metal only.) StuRat (talk) 17:24, 13 March 2013 (UTC)

I also found some unreliable scare pages and lots of reliable information that didn't mention toxicity. However, it's clear that bakelite was produced from phenol and formaldehyde, which are both toxic. Apparently the process was such that the finished product was not toxic itself, but the production certainly affected the workers. In addition, various substances were added to bakelite to make it cheaper, control the colour, or otherwise control certain qualities. According to some (unreliable) reports, asbestos could be among those substances. This seems plausible, especially in the case of insulators.

As to your cameras: I think existing mechanical damage is no problem at all. The main issues would be these:

• I found no sources on what causes the typical bakelite odor. It might be caused by trace amounts of phenol and/or formaldehyde. Likely not a big issue, as polyphenols, which are also toxic, are even considered healthy in the amounts found in apples. Formaldehyde should still be pretty ubiquitous anyway.
• If there is asbestos in your cameras, then inhaling whatever dust might be created when something breaks would be a bad idea.
• I guess there is going to be a lot of toxic gas if you heat or even burn bakelite. But that's also true for modern plastics, and I don't know whether bakelite is better or worse than those. Hans Adler 17:31, 13 March 2013 (UTC)

Once we have reliably sourced info, it should be added to the Bakelite article to provide a counter to all the misinformation out there. ~E:74.60.29.141 (talk) 18:38, 13 March 2013 (UTC)

Ok, did more research, found a few scientific studies. This one [4] is titled "Occupational Exposure to Airborne Asbestos from Phenolic Molding Material (Bakelite) During Sanding, Drilling, and Related Activities" -- 1) Some bakelite was made with asbestos, and may still be around. The study was conducted to assess the risks to modern workers. They conclude 2) Even if you drill and sand it, asbestos particles in the air remain well below present OSHA guidelines. (warning, WP:OR ahead) Thus, on the asbestos front, I am confident that the cameras pose no significant risk, even if sanded/drilled. While it is true that absence of evidence is not evidence of absence, I can find no reliable information indicating that old bakelite sitting on a shelf poses any significant health risk. SemanticMantis (talk) 19:56, 13 March 2013 (UTC)

One suggestion: Don't put it in sunlight, as some plastics degrade when exposed to sunlight. I don't know if Bakelite does, but see no reason to risk it. StuRat (talk) 20:21, 13 March 2013 (UTC)

Thanks StuRat. That is probably good advice, and something I hadn't considered. They are kept on a shelf which gets no sunlight and isn't above a radiator.217.158.236.14 (talk) 09:11, 14 March 2013 (UTC)

Some people around here are overly strict about removing requests for medical advice, so I'm surprised they left this one alone. But to be clear, we can't give you advice about what to do. If you catch a mesothelioma, we're not assuming any liability. Personally, I think we should provide relevant information in these cases, and I hope these links will be useful to you, but we can't be telling you what you ought to do. Wnt (talk) 03:37, 14 March 2013 (UTC)

WNT, I tried to make this as non "medical advice" as I could. I merely want to know if it's a dangerous substance. Since this is the sort of information that could be contained in Wikipedia, I hoped it would be ok to ask about this here. Perhaps I shouldn't have mentioned my cameras and made it personal though. Don't worry. I assume that anything I read here is merely "advice", with no factual background unless it has reliable cited sources. For what it's worth, I totally agree with the ban on medical advice.217.158.236.14 (talk) 09:11, 14 March 2013 (UTC)

I don't see this as a request for medical advice, as a doctor wouldn't answer such a question. Determining which objects are toxic and keeping those out of your home just isn't your doctor's responsibility. There are thousands of chemicals and materials in any home, and your doctor just can't research those all for you. StuRat (talk) 05:19, 14 March 2013 (UTC)

In my opinion, there are some requests for medical advice that should be answered, like "I was looking at some TV commercials from the 1950s which said that smoking is good for you. I am thinking of taking up smoking. Should I do it?" Not giving medical advice is a sound policy, but we also have to use human intelligence and tell our potential smoker exactly what we all know that every legitimate doctor on earth will tell him. --Guy Macon (talk) 05:35, 14 March 2013 (UTC)

Thank you all for your answers. It's much appreciated. I feel I understand the situation a little better now.217.158.236.14 (talk) 10:25, 15 March 2013 (UTC)

When did humans know Sun was a star like other stars in sky?

Humans long thought Earth as the center of the Universe, then the Sun as the center. I want to know when did humans know that the Sun is just another star like the others that humans can observe from Earth? --PlanetEditor (talk) 17:52, 13 March 2013 (UTC)

Anaxagoras already proposed that the sun was a "fiery stone", like other stars, although those couldn't heat us, since they were too far away. That obviously doesn't mean that plain humans would agree with him, or even be aware of his hypothesis. I imagine that not earlier than when the heliocentric model of our planetary system became established people would realize that the sun and the stars are actually the same kind of celestial body (more or less). OsmanRF34 (talk) 18:22, 13 March 2013 (UTC)

As per Star#Observation history: "In 1584 Giordano Bruno suggested that the stars were like the Sun, and may have other planets, possibly even Earth-like, in orbit around them, an idea that had been suggested earlier by the ancient Greek philosophers, Democritus and Epicurus, and by medieval Islamic cosmologists. By the following century, the idea of the stars being the same as the Sun was reaching a consensus among astronomers." Red Act (talk) 18:30, 13 March 2013 (UTC)

The first proof was when the suns spectra was first analysed and absorption lines were seen . I think this was by Fraunhofer in 1817. Stars also present absorption lines and so this was the first definite proof of the sun being another star. Ap-uk (talk) 21:46, 14 March 2013 (UTC)

Colossal multirotor

Suppose I had several hundred billion dollars and wanted to build a colossal multirotor transport capable of carrying six thousand (6,000) people. About how long could a nuclear reactor, such as those used in naval nuclear propulsion, keep such a multirotor up in the air hovering without landing? What about for a multirotor large enough to carry sixty thousand (60,000) people? —SeekingAnswers (reply) 18:34, 13 March 2013 (UTC)

I doubt the RD is for such speculations. You would have to solve several problems for having a flying nuclear reactor. OsmanRF34 (talk) 18:43, 13 March 2013 (UTC)

What sort of problems would have to be solved that haven't already been addressed in naval nuclear propulsion? And I don't think dismissing my question because it is speculative is fair, especially when it's not even all that speculative, in the sense that colossal rotorcraft are actually buildable with a large budget. People ask questions on the Science Reference Desk about even more speculative things like relativistic baseballs (there is currently a question above on this topic) --- and for that matter, I've seen much weirder speculative subjects on the SciRefDesk than relativistic baseballs in my years here --- and still get answers. —SeekingAnswers (reply) 19:07, 13 March 2013 (UTC)

It would be dangerous yes, but let's ignore that. If we assume it would provide the energy needed for years, then maintenance would be a more immediate issue. You'd need the ability to shut down some rotors to do maintenance on them, while the others take up the slack, or you'd be limited to having to land when the first rotor failed. You might be able to design them so they need maintenance less often, though. Oil could be continuously replaced while in operation, although you might not be able to fully flush out the fluids while it's running. You'd also need a fire suppression system to stop a fire in one part of the ship from spreading to another. Then there's the risk of foul weather. You'd need to steer clear of hurricanes, tornadoes, and such. Also, can we assume it could be resupplied mid-air ? StuRat (talk) 18:45, 13 March 2013 (UTC)

Am I understanding correctly from your answer that a single nuclear reactor would generate enough power to keep a 60,000-person rotorcraft up in the air for years? —SeekingAnswers (reply) 19:07, 13 March 2013 (UTC)

Naval nuclear reactors run for years (25+ in the case of Nimitz-class carriers) without refueling, so in that narrow regard, yes, it's reasonable. Ultimately, though, that says little more than "fuel is not the constraining factor for nuclear aircraft". We could burn a lot of time on guessing at the precise engineering limits of reactors, weight, material strength, and such, but there's no real need. — Lomn 19:53, 13 March 2013 (UTC)

Well, you'd have to strip of all the safety equipment to get the weight down, certainly, and I really didn't consider if the reactor can provide enough power to lift itself and the ship. The OP seemed to want us to take that part of the Q as a given, which I did. Once you accept the premise, then, since those type of reactors output the same power for years, the power would no longer be a limiting factor. StuRat (talk) 20:08, 13 March 2013 (UTC)

What does a ship-type reactor, with cooling, controls, shielding and auxiliary equipment weigh? Does it have the power to even lift itself off the ground? This site [5] says a 26 megawatt electric output submarine reactor, with water and associated equipment, weighs about 1000 tons, or 2000000 pounds. A random website [6] gives the impression that lift is about proportional to input power, and 300 hp (224kw) might lift 3400 pounds, (1540kg) neglecting 10-15% devoted to the tail rotor. Would a multi-rotor massive aircraft even need a tail rotor, or could the rotational sense of different rotors balance each other out. The sub reactor, with all its associated equipment, would thus require about 0.224 mw*2000000/3400 or 132 mw to rise off the ground, neglecting power transmission, general structure, passengers, baggage, food service carts, and aerodynamic shape. It would seem to be be 80% deficient from the get-go. Lots of redesign and weight reduction would be indicated. Edison (talk) 20:05, 13 March 2013 (UTC)

You've got to watch the capitalization on your metric prefixes, or we will end up with a 132 milliwatt reactor (that might be more appropriate to power a firefly, rather than a Firefly-class ship). :-) StuRat (talk) 20:14, 13 March 2013 (UTC)

You know, you can actually get a fair number of references for this by looking at people who have analyzed the physics of the Avengers' helicarrier, which could certainly pack 60,000 people. Here's one such piece, and another. The net answer is that a nuclear reactor (nor any remotely-conceivable set of reactors) can't keep the thing off the ground for any length of time (because it can't ever get off the ground in the first place), because (addendum) helicopters don't scale like that. Not sure how I chopped the end of that sentence off. — Lomn 20:52, 13 March 2013 (UTC)

Hmm, interesting. Reading through the links you provided, the latter link at least seems to conclude that, for the helicarrier, power itself isn't a problem, but the size and number of engines; that is, the helicarrier could fly -- it just needs larger (according to the former link) or more (according to the latter link) rotors and engines. —SeekingAnswers (reply) 20:56, 13 March 2013 (UTC)

Also, the helicarrier is very different from what I had in mind when I asked the question. What I had in mind was a rotorcraft with arrays of many (tens or even hundreds) of relatively small rotors, as it seems to me that using four enormous rotors as the helicarrier does is a terrible idea: (1) with enormous rotors, if any of them fail, as one does in the movie, the result would be catastrophic (2) by having many small rotors, each rotor would be subject to much less severe stress forces, so they could be made of materials with less high stress tolerance (3) by having many small rotors, you could shut some down for maintenance while the others keep the rotorcraft hovering. —SeekingAnswers (reply) 20:56, 13 March 2013 (UTC)

By the way, helicopters are pretty precariously balanced with regards to spin, so your hundred-rotor helicopter might still spiral right out of control with the loss of a single rotor. It's not at all like a hundred-propeller aircraft, which would keep on gliding with the loss of any engine, due to its nice stable fixed wings. Tarcil (talk) 21:32, 13 March 2013 (UTC)

Presumably you'd slightly increase the speed of rotors spinning in one direction, and decrease the speed of those spinning the other way, to compensate for the down rotor. StuRat (talk) 23:10, 13 March 2013 (UTC)

That's no problem; just always shut them down in symmetrical pairs. So if you need to perform maintenance on any particular rotor, just shut down its opposite-spinning counterpart on the other side of the rotorcraft as well. —SeekingAnswers (reply) 06:56, 14 March 2013 (UTC)

That would work, but now you've doubled the number of rotors shut off. So, if your design could stay aloft with, say, 3 rotors shut off, then you've just limited it to 1 rotor down, since even having 2 down would mean a total of 4 would need to be shut off (unless you get lucky and the 2 which fail just happen to be opposites). StuRat (talk) 14:44, 14 March 2013 (UTC)

You can use lightweight nuclear reactors e.g. the BES-5, these were used on board US-A satellites:

"The US-A programme was responsible for orbiting a total of 33 nuclear reactors, 31 of them BES-5 types with a capacity of providing about two kilowatts of power for the radar unit. In addition, in 1987 the Soviets launched two larger TOPAZ nuclear reactors (six kilowatts) in Kosmos satellites (Kosmos 1818 and Kosmos 1867) which were each capable of 6 months of operation.[1] The higher-orbiting TOPAZ-containing satellites were the major source of orbital contamination for satellites that sensed gamma-rays for astronomical and security purposes, as radioisotope thermoelectric generators (RTGs) do not generate significant gamma radiation as compared with unshielded satellite fission reactors, and all of the BES-5-containing spacecraft orbited too low to cause positron-pollution in the magnetosphere.[2]"

Count Iblis (talk) 23:29, 13 March 2013 (UTC)