Wikipedia:Reference desk/Archives/Science/2007 January 15

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January 15

Why do some people sneeze when in pain?

I noticed that when people try to hold back the pain, they cry - or the tears just fall down automatically. For me there is no tear, but I sneeze instead. Like the time when I was having my tattoo, or when I was having a facial, or having my eyebrows plucked. Just wondering how the pain, particularly in my face area, triggers the sneeze. Thanks for answering this.203.13.226.2 02:11, 15 January 2007 (UTC)

Hmm... Do you happen to sneeze when you go out in the Sun too? Take a look at photic sneeze reflex. Apparently, all it takes is a bit of stimuli on the face. Happens all the time with me. — Kieff 02:32, 15 January 2007 (UTC)

A bit of a stretch I think as the optic nerve needs to be stimulated in order for the photic sneeze reflex to be the culprit. --hydnjo talk 18:22, 15 January 2007 (UTC)

While I do sneeze when out it the Sun, pain in the facial area usually makes me sneeze the same way. So I don't think photic is to be taken so seriously (check the article, it mentions this), although I guess it's a topic that needs more research. — Kieff 20:27, 15 January 2007 (UTC)

According to the article, the sneeze reflex is controlled by the trigeminal nerve, which also conveys pain sensation from the face. Put two and two together, and it seems to make a bit of sense. Of course it's oversimplified, mainly because the details of the reflex haven't all been worked out, but it's at least plausible. --David Iberri (talk) 20:31, 15 January 2007 (UTC)

I've always associated the reflex with pain – in the case of bright light the pain from the iris sphincter muscle straining to constrict the pupil. I am a bit surprised to find out this is not part of the received wisdom for the photic sneeze reflex, as reflected in our article.  --Lambiam^Talk 07:58, 16 January 2007 (UTC)

Navel type: innies, outies and ???

My navel is shaped like a C. How did it get that way, and what would it be called? One thing I should probably mention is that I was born with only one artery in my umbilical cord. Wiwaxia 07:27, 15 January 2007 (UTC)

The article on navel says it is just a scar and the reason for it being an outie or innie is not known. However, I would guess that it has to do with the fat underneath or something, since I used to have an outie when I was young, then for awhile, the half-and-half that you have, and now it's a slightly lopsided innie. So it seems like it sunk in as I grew up. BTW, I'm not large, so I didn't grow inches of fat around it to cause it to become an innie.

The fact that you were born with only one artery might have caused the scar to heal in a way to make it lopsided, and as for what it's called, the article does only say innie and outie, so if it's both, it's probably just both. --Wirbelwindヴィルヴェルヴィント (talk) 07:39, 15 January 2007 (UTC)

Subway Tunnels and Fallout?

Could it be possible to use subway tunnels as a safe method of travel in a post-nuclear war, fallout ridden land? I should think it would be, but I just feel safer asking what you all think. Here7ic 08:44, 15 January 2007 (UTC)

Hiding in underground subway is one of your best bets in nuclear detonation, but after detonation it may get contaminated is well as it is not sealed, practically a giant wind tunnel; millions of rats around you and others. But then, I am no expert, that's just what I think. --antilived^{T | C | G} 09:19, 15 January 2007 (UTC)

I think you are assuming things that would otherwise make this improbable. Nuclear war would almost certainly target, directly or indirectly, the largest power stations in thw world so there would be unlikely enough power for subways or anything else that required ongoing electricity. Large power stations require lots of humans to run, and most of mankind would have perished. Also, unless you lived underground next to a subway exit, you would have to emerge in the open. This would mean you are already protected from fallout radioactivity with some sort of suit. Which means you didn't need the subway anyway. Bicycle would more suitable :) Sandman30s 09:50, 15 January 2007 (UTC)

Bear in mind that many underground lines aren't in fact fully underground; the Circle Line of London Underground is open for much of the route between Paddington Station and High Street Kensington for example, and even on deep-level lines, the trains move the air as they go (just before a train arrives in a station, you can feel a warm breeze blow across the platform), which would suck fallout through the ventilation chimneys. Laïka 12:17, 15 January 2007 (UTC)

Air circulation would be a major issue — it wouldn't provide a lot of safety from fallout for that reason. In the very short term it might be somewhat better than being outdoors but not as good as being in a house with all of the windows closed and the vents shut. --24.147.86.187 16:14, 15 January 2007 (UTC)

I think I should have been a bit clearer. Could subway lines be used as an enclosure by which you could travel safely by walking or cycling, etc. Obviously the train cars wouldn't be very useful, as the power would be out. As for not needing to leave (being in an already safe house, etc.), I should think one would need to leave if perhaps there was a long-standing issue. Perhaps you're alone. Perhaps you need supplies. The exposure you'd receive in the time you travel to the tunnel would surely not be enough harm you fatally ;-) Here7ic 19:48, 15 January 2007 (UTC)

According to our Nuclear fallout article "Fallout radiation decays exponentially relatively quickly with time. Most areas become fairly safe for travel and decontamination after three to five weeks" so in a case of nuclear detonation and you happened to be around your best bet would be go down to underground subway station with a few weeks of supplies before the detonation and stay there for that amount of time. --antilived^{T | C | G} 22:28, 15 January 2007 (UTC)

That wouldn't be as good a bet as, say, going into the country (not near any missile silos and bases) and just staying indoors. As noted a considerable amount of fallout would still enter into subways because of their air circulation. You would be better off inside a house with the chimney dammed up. Of course in a house you are much more likely to suffer blast and fire effects, hence being away from possible targets. --24.147.86.187 16:05, 16 January 2007 (UTC)

Would there not be a problem in that I expect that most underground/subway systems are in major cities which would be the most likely targets for bombs, and hence the levels of fallout would be higher than the mean?

On a related matter, would bombs cause collapse in the tunnels, rendering them less useful? --Neo 22:47, 15 January 2007 (UTC)

I don't think subways would be targetted for bombs. In order to really damage them you'd have to allow the weapon to go off relatively close to the ground, which would decrease the efficiency of your being able to target surface structures. Usually targeting of cities is concentrated on major political and economic interests, not things like civilian infrastructure of that sort. Again, it would be very inefficient, a real waste of your firepower, to target subways or other underground structures which did not have military importance. --24.147.86.187 16:05, 16 January 2007 (UTC)

A nuclear bomb in subway would do far less damage than an above ground detonation. Blast, thermal radiation and ionising radiation are all effectively insulated by the thick concrete tunnel and the earth above it. Plus it will be a lot easier to seal the subway system to prevent contamination and spread of the fallout. --antilived^{T | C | G} 10:51, 16 January 2007 (UTC)

Many subways were made by an open cut and are immediately below street level. Others such as in London are dug way down to go below a couple of other subways. Such deep tunnels would be highly immune to blast and radiation, and would only be subject to fallout being in the air pumped in by the air circulating system. The power would doubtless go off, so voila, no air pumped in from the surface. Natural circulation should bring in enough fresh air for quite a few people. Fallout particles are described in civil defense literature as being not all that fine, so their drift should not extend too far from the surface openings where a subway surfaces or from interconnections to portions which surface. Oxygen depletion in a firestorm such as that in Dresden, Germany during the WW2 allied terror bombing killed people who were in below ground shelters and shielded from the heat. Edison 15:53, 16 January 2007 (UTC)

Many subway systems I have seen have lots of vents all over the place to the surface. I think you'd have very spotty radiation in many parts of them. That all being said, I'm fairly sure that the Moscow subways were used for Civil Defense drills in the 1960s. --24.147.86.187 16:06, 16 January 2007 (UTC)

Copying documents before xerography

I want to know what technologies were used, prior to the invention and subsequent widespread use of xerography, to copy documents (with graphic images and text) from a paper original. The page on duplicating machines describes processes involving the preparation of a stencil, and carbon copying makes multiples at the time the original is produced. I understand that text documents could be (and were) retyped or otherwise transcribed, but what was done with non-text images, e.g. when no photo negative was available from which to make additional prints? -- Thanks, Deborahjay 08:49, 15 January 2007 (UTC)

One method that was commonly enough used that its name entered the English language was the Photostat. I suggest exploring List of duplicating processes. --Anonymous, January 15, 2007, 09:27 (UTC).

Your suggestion is well taken. I've moved my particular (time & place) question to the Discussion page for Photostat machine, and meanwhile checked an unabridged dictionary to find that the verb "to photocopy" entered the English language as early as 1920. -- Thanks! Deborahjay 10:25, 15 January 2007 (UTC)

Our article on Mimeograph machines says "A variety of specialized styli can be used on the stencil to render lettering or illustrations by hand against a toothy plastic backing card. On-stencil illustration is an art." Gandalf61 10:36, 15 January 2007 (UTC)

Diazo was a process used to reproduce documents; see reprography. The output was blue-on-white, leading to the classical whiteprint. Cyanotype produced the even-earlier blueprint.

Atlant 15:43, 15 January 2007 (UTC)

Does anyone else remember those awful purple-on-white duplicated handouts and test papers that they used to give out at school? I'm not sure how they were made but I remember one of the teachers saying that it was cheaper than using the photocopier (which they were not allowed to use without permission from the head - this was the mid-80s). They smelt of chemicals, the resolution was poor and they were sometimes impossible to read if the source text was too small. I really hated them. --Kurt Shaped Box 15:50, 15 January 2007 (UTC)

Oh yeah! We're probably dating ourselves by remembering those copies from a Mimeograph machine.  ;-) --hydnjo talk 16:43, 15 January 2007 (UTC)

Thanks for putting a name to it for me. I used to wonder what those machines were called and how they worked, though I'd forgotten I'd ever wondered about them until I started reading this discussion... ;) --Kurt Shaped Box 18:11, 15 January 2007 (UTC)

The purple-on-white gizmos were spirit duplicators. I knew them as the trademarked name Rexograph although I wouldn't guarantee that's the correct spelling. These transferred a waxy ink from the backing sheet onto the "master". The duplicating machine then wet each sheet of paper with a little bit of a solvent and some of the wax was transfered from the master sheet onto the sheet of paper as it passed through the machine. Purple was by far the most common color, but you could get masters in a variety of colors and you could put more than one color onto a single master sheet, allowing a crude form of spot color. Mimeograph machines worked quite differently.

Atlant 23:59, 15 January 2007 (UTC)

If you have 20 minutes, this somewhat dated but still relevant tv show explains the history of photocopiers pretty well, [1]. Tuckerekcut 18:05, 15 January 2007 (UTC)

The smelly blue on white copies were known as Ditto. The original could be typed or handwritten, and transferred the solid ink from a backing to the original. It could make far fewer copies than a Mimeograph, which could use black ink, used a literally cut stencil, and could make many thousands of copies. Another early spirit process was Hectograph. Edison 18:57, 15 January 2007 (UTC)

Acids & Metals?

Do all metals react with acids giving out hydrogen? If not,why?Vichu satheesh 11:29, 15 January 2007 (UTC)

I'm going to make a wild guess that this is a homework question - right? So, rather than answer directly, I'm going to suggest that you read our metal article and pay particular attention to the first "See also" link. If you still need help after that, then come on back. --hydnjo talk 18:43, 15 January 2007 (UTC)

animal adaptations

how would a stoat/short-tailed weasel adapt to the environment if it were to be moved from the north pole to singapre and kept as a domestic pet?? --203.124.2.7 12:03, 15 January 2007 (UTC)

There are no staots or weasels at the north pole. They are wild animals that live in the countryside and they are not suitable to keep as domestic pets.--Shantavira 12:08, 15 January 2007 (UTC)

If you want something long, fast and weasely for your home, get a ferret. --Kurt Shaped Box 12:23, 15 January 2007 (UTC)

check wikipedia's description of a stoat"The stoat can be found almost throughout the northern temperate, subarctic and arctic regions, that is in Europe, Asia, Canada and the United States" it can be found in the north pole.its also known as a ermine..--203.124.2.7 12:28, 15 January 2007 (UTC)

by the way...i dont wat to keep it as my pet!it is 4 my science assignment.we have to choose an animal that can be found in the north pole and write how it would adapt to the environment if it was brought to singapore and kept as a domestic pet.i came across the animal stoat/ermine/short tailed weasel and decided to choose it but i dont understand in what way would it need to adapt to the environment and how??any ideas?or shd i change my animal??--203.124.2.18 12:55, 15 January 2007 (UTC)

Perhaps clarify with your science teacher whether your assignment might include the area of the Arctic Circle rather than just the North Pole. You'll have a wider choice of animals (or stick with the ermine?), besides more information on the habitat's conditions, e.g. climate, vegetation, etc.-- Deborahjay 14:23, 15 January 2007 (UTC)

I think Deborahjay has given you the best approach. So first find out how the animal is adapted to the arctic environment, what its requirements for food, shelter, breeding, etc. are. Then think of how the arctic would be different from your own environment, and figure out how the difference would affect the animal. Obvious issues would be matters like temperature control, diseases, and foodstuffs. I think you will be amazed at how well land mammals can adapt to most environments, especially if there is a human around to provide a little modification here and there. I think you have made a good choice, assuming that you are not expected to domesticate to the level of a dog or cat. --Seejyb 22:46, 15 January 2007 (UTC)

i have decided to stick with the ermine...and studied its natural habitat and diet. wat shd i do next??i mean in which aspects will the ermaine nedd to adapt?eg.temperature....how will moving from a cold climate to a hot climate affect the ermain and wat way does it need to adapt to live in a hot climate(as in 27 degress or so)HOW will i know that??--203.124.2.17 12:03, 16 January 2007 (UTC)

Tunnel transport system

Hi there,

I am looking for an off the shelf tunnel transport system that would satisfy the following criteria:

• Battery operated
• Capable of travelling 3km on one charge
• Capable of being driven by an operator in the vehicle or remotely operated from the tunnel control room.
• The vehicle should be equipped with visible and infra red lighting and camera systems
• The vehicle should also contain a limited volume water fire extinguisher that can discharge to either side of the vehicle on request.
• The vehicle must travel at not less than 10km/hour.
• The vehicle must dock with a charger at the base of a shaft where it is designed to be stationed and automatically recharge without human intervention.
• The vehicle must be capable of carrying both personnel and materials/tools to a point of work, provide temporary lighting and be removable using a crane through the shaft/head-house for maintenance and repair.

Any ideas??

Thanks, John —The preceding unsigned comment was added by 217.33.212.2 (talk) 17:02, 15 January 2007 (UTC).

An elevator? —The preceding unsigned comment was added by 138.29.51.251 (talk) 21:08, 15 January 2007 (UTC).

You mean a battery-operated elevator capable of travelling 3km on one charge, while containing a water fire extinguisher that can discharge to either side of the cage? Sure, that will do. Where do we get one off the shelf?  --Lambiam^Talk 08:02, 16 January 2007 (UTC)

Paper and Water

I have an interesting idea: if a piece of regular, 8.5 by 11 paper was placed on the surface of water, and an object (preferably something sensitive to movement) was dropped from approximately 5 meters, then what would happen to the object and the paper? This question came into my head when I heard that the same experiment described above was repeated. The only difference was that a diver had dove into the paper, and broken both arms. Could, in theory, this be true? -- PSv255 (a user, but not signed in at the moment)January 15, 2007, 1:45 EST

If the paper does not rip on impact, I can see how the diver's arms would break. The greater surface area of the paper results in a much higher drag while entering the water, though I don't think a standard 8.5 by 11 is big enough to break someone's arms. --Carnildo 22:05, 15 January 2007 (UTC)

Well...any size you choose suitable for that matter! :)

I'm not sure normal paper would work. I seem to remember something about paper fibers absorbing water, which essentially breaks the surface tension. Maybe waxed paper? --Wirbelwindヴィルヴェルヴィント (talk) 01:55, 16 January 2007 (UTC)

I don't think the issue is with the paper per se, but rather with the fact that the paper lies on water, and the hydrogen bonds on the water's surface are actually very strong. That being said, I doubt the diver dove from a height of only 5m.

Human Genome Project

How many scientists were involved in the Human Genome Project?Hotdancer23 19:24, 15 January 2007 (UTC)

All of them, and all humans too as everyone has genes :]

I think it's pretty safe to assume the OP is talking about the project to map the human genome. Have you read human genome project? There wasn't one single project, it has been a collaboraive effort, pretty huge actually, it may be hard to estimate even a rough number of scientists that were involved. Vespine 21:53, 15 January 2007 (UTC)

This MS Word document lists all the members of the International Human Genome Sequencing Consortium, the scientific contributors to the non-commercial project. Its taken from the supplemetary data of:

• Initial sequencing and analysis of the human genome. Nature. 2001 Feb 15;409(6822):860-921. PMID 11237011.

You might, or might not, wish to add the names of the people who worked on Craig Venter's competing Celera Genomics sequencing effort, published as:

• The sequence of the human genome. Science 2001 Feb 16;291(5507):1304-51. PMID 11181995.

The version of the human genome the scientists use incorporates both of these datasets. However, the sequencing was just the beginning. A lot of work has gone into annotating the genome. This has taken much effort from lots of other people. The entire list of research centres, and the scholarly papers listing the individuals, involved in creating the version of the gemone scientists use is here Rockpocket 08:22, 16 January 2007 (UTC)

I'm not sure if those published lists would actually tell you all the scientists involved — a lot of the work was delegated to technicians (sequencing is quite boring, routine work) who are probably not mentioned in the published articles. --24.147.86.187 16:57, 16 January 2007 (UTC)

The International Human Genome Sequencing Consortium list includes everyone from the project leaders all the way down to the tea-lady. Actually thats an exaggeration, but they do list all scientific staff (including the sequencing technicians, as I happen to know a few of them on the list). Rockpocket 05:43, 17 January 2007 (UTC)

Here's a back-of-the-envelope rough-guesstimate method of calculating the number of people involved, that treats the question as a Fermi problem.

• Our human genome project article gives the budget for the project as $3 billion, and the sequencing took place from roughly 1990 to 2000. Figure $300 million per year to support the project, then.
• Guesstimate that a scientist costs upwards of $100,000 per year (figure that 30% to 50% of that is just overhead: heat, light, human resources, office space, etc.). A senior scientist will cost $90,000 and up just in salary; a senior administrator will be $150,000 or more; a fresh-out-of-college technician goes for $30,000 or $40,000.
• Assume that each participant blows through another hundred thousand dollars a year in equipment (amortized over the life of the project) and reagents. This number is the one that is likely to have the greatest uncertainty in it.
• Divide $300 million by $200 thousand to get 1500 full-time scientists for ten years.

Choose different assumptions or incorporate other outside information to get a better guess, of course. You can also choose to include scientists and engineers who worked on related problems but who weren't funded by the HGP; this gets into some horribly broad gray areas. The number of people working on the project no doubt fluctuated greatly over the course of the work. TenOfAllTrades(talk) 20:03, 16 January 2007 (UTC)

For reference, the HGP sequencing consortium involved 20 sequencing centres in six countries. [2] Following on from the 1500 estimate above that would imply 75 personel per centre. Sounds slightly high, but certainly in the right ballpark. David D. (Talk) 20:13, 16 January 2007 (UTC)

Paper and water (different question)

The heading above ("Paper and Water") reminded me of a question I have been meaning to ask for a while. Why is it that when a piece of paper gets wet, it wrinkles, and then it stays wrinkled even after it has dried? Are the fibers in a sheet of paper normally under some kind of tension that is released when the paper gets wet? —Bkell (talk) 22:10, 15 January 2007 (UTC)

• I have a different approach: the water dissipates the paper "particles", and disconfigures them in a way that when the paper dries, then the wrinkles will stay that way.--PSv255 23:40, 15 January 2007 (UTC)

• Paper is made by creating a slurry of fiber and water, pouring it into a frame, and waiting for much of the water to drain off. Then the damp sheet of fibers is pressed between pieces of absorbent material to remove the rest of the water and create a flat surface. If a finished piece of paper gets wet, its fibers become more free to move around in the wet part. They expand due to absorption of water. Then when they dry out again, they aren't under pressure, so they don't form a flat surface. The fibers may also be subject to internal tensions from uneven wetting, which adds to the wrinkling of the surface. FreplySpang 11:45, 16 January 2007 (UTC)

If the paper is wetted unevenly, the fibers in the wetter parts absorb more water, so they expand more and take up more room, so that the paper cannot stay flat and develops bumps. If a piece of paper is wetted evenly, it stays reasonably flat while wet. But then, when it dries up, it typically dries up unevenly, and the driest parts shrink more, causing the paper to wrinkle. When a wrinkle dries up, the fibers stick to each other, so the wrinkle has then been fixed.  --Lambiam^Talk 18:27, 16 January 2007 (UTC)

Lemur taxonomy

The classification goes like this

• Suborder Strepsirrhini
  • Infraorder Lemuriformes
  • Infraorder Chiromyiformes
  • Infraorder Lorisiformes

According to the article, only members of the infraorder lemuriformes are lemurs. However, aye-ayes are considered lemurs even though they are of the infraorder chiromyiformes. So my question is, should the lemur article be changed to expand the definition of lemur (to encompass both infraorders)? --JianLi 22:14, 15 January 2007 (UTC)

According to the Strepsirrhini article: "...the Aye-aye alone in its own family. However, the Aye-aye's placement is tentative. It is placed in its own infraorder (Chiromyiformes), and it is uncertain whether this infraorder split off from the ancestral strepsirrhine line before the lemurs and lorises, or after." According to my biological anthropology professor, Strepsirrhines are divided only into 2 infraorders: lemurs and lorises, eye eyes being lemurs. However, you should be aware that the classification of primates is under a lot of debate in the scientific community and there are a lot of inconsistencies on Wikipedia. Even the most recent textbooks on the subject differ from each other in their classification.