Wikipedia:Reference desk/Archives/Science/2006 August 27

< August 26	Science desk archive	August 28 >

Humanities

Science

Mathematics

Computing/IT

Language

Miscellaneous

Archives

The page you are currently viewing is an archive page. While you can leave answers for any questions shown below, please ask new questions at one of the pages linked to above.

NHS Eyecare voucher

I am a 17 year old in Full-time education in the UK. I have recieved free glasses on the NHS about 6 months ago but I feel 1) they are too weak and 2)that I don't suit them at all. Am I elligible for a new pair or do I have to wait a certain length of time?

Yours, Christopherx

Hello! Please note that wikipedia is international, and many of us don't know which "NHS" you mean... perhaps the Canadian system? More details will help us answer your question...Nimur 00:41, 27 August 2006 (UTC)[reply]

Ironically Nimur considering all the crap we give people who ask questions here about doing it, this time its you who should of searched for NHS before posting. Philc _T^E_C^I 00:53, 27 August 2006 (UTC)[reply]

Nah, he should HAVE searched. I can't stand it when people write phonetically. Please promise me to remember. :) There's cookies in it for you... - Mgm|^(talk) 10:54, 27 August 2006 (UTC)[reply]

I did search that, but I wasn't sure if there are other nations which have nationalized health systems also called NHS. Traceroute the poster's IP. It is debatable what .LND means; it could be London - but I don't see a transatlantic route from here... and it could be London, Ontario which would fit nicely with Niagara_Health_System... Nimur 01:27, 27 August 2006 (UTC)[reply]

Either way, it sounds as though you should take them back to your optician and ask your question there.--Shantavira 07:45, 27 August 2006 (UTC)[reply]

Edited.

This guy says in his question he is a student in the UK, I think it would be quite obvious he is talking about the “National Health Service” of the UK. I don’t know the answer but finding out would be simple enough, ring the NHS helpline (0845 46 47)

Where'd you get them? I would chat to the people in the opticians about it, in a friendly, polite manner, and ask their advice. Some opticians go further than the NHS requires them, or assume it grants you more than it does, so it's worth asking. Otherwise, I think it's a pair a year if the opticians won't swop them from the kindness of their heart. 86.140.31.143 13:40, 31 August 2006 (UTC)[reply]

group of doves

What is the proper term for a group of doves? A group of quail is a covey. A gaggle of geese, etc.

Many are common:

dole of doves
dule of doves
pitying of turtledoves
pityeous of doves

That would be "piteousness" or "pitying" or "prettying", but not "pityeous". JackofOz 04:01, 28 August 2006 (UTC)[reply]

flight of doves
bevy of doves
cote of doves

Google wins again. Nimur 01:01, 27 August 2006 (UTC)[reply]

So does Wikipedia. See List of collective nouns for birds.--Shantavira 07:50, 27 August 2006 (UTC)[reply]

Doxycyclin

can doxycyclin be used as prophylaxis against leptospirosis and plague in children ? The preceding unsigned question was asked by User:59.95.192.77

~~No.~~ Nimur 01:22, 27 August 2006 (UTC)[reply]

Yes.To add further comment, doxycyclin can be used as a prophylaxis against leptospirosis and plague in children. My previous response was because I did not understand a single word of your question. Nimur 01:24, 27 August 2006 (UTC)[reply]

Do you have reason to believe there is some danger of infection from the plague where you live? If so, please contact the World Health Organization ASAP! --bmk

Reported human cases (yellow) and animal carriers (red) of plague.

There are occasional cases of the plague reported on all continents except for Australia and Europe. Any place there are marmots, rats, chipmunks, squirrels, or nearly any other large rodent in a temperate climate there is a (usually) small risk of plague infection—this includes the United States, which reports about a dozen cases per year of the plague. (The incidence is probably higher; some people may become infected with the plague bacterium – Yersinia pestis – without developing symptoms severe enough to require medical attention; it's also possible that they may be treated without the doctor recognizing the plague.) TenOfAllTrades(talk) 05:26, 27 August 2006 (UTC)[reply]

Diptera on Board

What happens if I release a few diptera inside a moving aircraft? Will they hit the rear wall since they can not fly as fast as the airplane?--202.161.131.76 05:30, 27 August 2006 (UTC)[reply]

You can actually do a similar experiment in a speeding car. (Please don't do it, or otherwise cause trouble, on an airplane!) The next time you see a fly around the house, chase it around a bit to see how fast it can fly, then catch it in a jar. Get someone to drive you around in a car with all the windows closed, release the fly and see what happens! Melchoir 05:46, 27 August 2006 (UTC)[reply]

Thank you. But I don't think that answered my question. Or, do you mean flies can actually travel faster than airplanes and that's why they will survive?--202.161.131.76 06:09, 27 August 2006 (UTC)[reply]

I mentioned the fly's speed because, to be sure of mimicing the situation on an airplane, you should try driving faster than the fly can fly. But that's not the only observation worth making: for example, if you drive slowly, does the fly appear to struggle? How about if you drive just under its max speed?

Anyway, no, I haven't answered your question yet; that would ruin the surprise. Wouldn't it be more fun to try it? Melchoir 06:16, 27 August 2006 (UTC)[reply]

No, the diptera won't hit the wall. They'll fly around the cabin annoying the passengers. Seriously though, at the beginning of the flight, when the airplane has finished lifting off, everything in the airplane will be moving at the exact same speed as the airplane. So any object in the plane will not be moving relative to any other object in the plane (including the floor and walls). If you release the diptera, they'll start flying around the cabin just as they would in your house.

Basically, there's no such thing as absolute speed. Who says the airplane is flying at a high speed? Who says the airplane is moving at all? People on the ground say it, but if I'm in the airplane, I don't care about what people on the ground say. I say that the airplane is not moving, because I don't see it moving. --Bowlhover 06:24, 27 August 2006 (UTC)[reply]

Yes of course! You dont feel it moving, and niether does the fly becuse the seat and the air are moving (wrt earth. So you both behave as you would if you were at rest.--Light current 22:50, 28 August 2006 (UTC)[reply]

OK folks. I am pretty convinced. Thanks a lot. And of course, I will experiment it in a speeding car ... when I'll manage to drive it faster than a fly ..... when I'll have a driving licence and ..........a car. :-) --202.161.131.76 07:02, 27 August 2006 (UTC)[reply]

Ah, but when you have a licence and a car, it becomes much harder to convince other people to drive you around while you perform experiments and take notes. And you have to worry about traffic laws, and not killing people... so enjoy your innocence while it lasts! Melchoir 16:29, 27 August 2006 (UTC)[reply]

any major application of heat,internal energy and work

i request you to send me informations about any major application of heat, internal energy & work for my mini project with the real chemistry behind the application.

         thank you,--59.163.146.11 05:54, 27 August 2006 (UTC)[reply]

If I remember my history correctly, these concepts were originally motivated by steam engines. Today thermodynamics has been applied to just about everything. If you have any particular interest within the physical world, you can probably find a way to build a project around it! Melchoir 06:04, 27 August 2006 (UTC)[reply]

As noted by Melchoir these concepts belong to the realm of thermodynamics. In general no chemistry is involved. But an application is found in calorimetry, which is used in measuring the heat of chemical reactions. Basically any chemical reaction produces some heat, but the obvious ones to produce measurable amounts of heat are combustion. You could, for instance, burn charcoal, which is almost all carbon. If I'm not mistaken the reaction is something like C + O₂ → CO₂. You don't want to produce carbon monoxide, so make sure the air supply is sufficient. --Lambiam ^Talk 09:11, 27 August 2006 (UTC)[reply]

Theory of Relativity in Simple Terms

I know a little bit of high school physics at the most. I am a graduate, but of a different discipline. I have heard several times people, who do not have much to do with physics, talk about "Einstein's Theory of Relativity". I also want to join the talk. Can anyone explain to me, in simplest sentences, what this theory is all about? One paragraph will do. Why does this theory carry significance in areas other than physics? By the way, I have rummaged through the Internet but with no luck for me.--Mr. Inquisitive 08:10, 27 August 2006 (UTC)[reply]

Our articles on Introduction to general relativity and Introduction to special relativity are intended as non-technical articles on this subject. If they are not suitable for your needs, I suggest you post on their talk pages explaining what you don't understand, so these articles can be improved.-gadfium 08:38, 27 August 2006 (UTC)[reply]

The absolute simplest explanations are something like this: Special Relativity says "c, the speed of light in a vacuum, is the speed limit for everything, and things like space, time, mass and energy will distort as you get faster and faster to accomodate this". General Relativity says "instead of masses causing spooky forces that attract each others like Newton's Law of Universal Gravitation says, the masses actually bend space and time, and in the absence of other forces objects moving close to those masses travel along paths which to them look like straight lines, but which to external observers appear like curves, and again space, time, mass and energy distort to accomodate the effects of this". Confusing Manifestation 09:23, 27 August 2006 (UTC)[reply]

It also says that on a cosmic scale the passage of time is not absolute, rather the experience of the passage of time is dependent upon the relative motion of objects. Also it posits that time is a dimension, and the way to picture that is to picture time as a coordinate, along with the three physical coordinates we are familiar with. General relativity suggests that time, mass and motion are inextricably linked, unlike here on Earth where they occur as discrete forces. Anchoress 11:29, 27 August 2006 (UTC)[reply]

I believe, many years ago, someone offered a substantial reward for whoever could describe relativity in (I forget exactly how many) words. Einstein himself refused to enter the competition saying that it was impossible. The theory carries significance in areas other than physics because, at the most fundamental level, everything in based on physics (unless you're of a particularly religious belief). Its significance really comes about however, because it is not really a theory in itself, but a theory about other theories. I probably haven't been much help, have I?

Lol it reminds me of a joke I read somewhere (or at least I think it's a joke), that there are only three people who have ever really understood Relativity; Fermi, Rutherford and Dr Hawking. Anchoress 23:07, 27 August 2006 (UTC)[reply]

I can understand at least the challenge of putting such a vast theory (theory of theories, rather. Right!) in plain words in a summarized form. I'm sure you guys would have made the most potent candidates of "describe-relatiity-in-words" contest. However, these answers are still a little too abstract for me to grasp, perhaps partly because of my background and partly because of the intricacies of the theory itself. I am still waiting for some more answers to come as building blocks - this time with a few comprehensible examples, if possible. So far so good. Thanks a lot. --Mr. Inquisitive 01:20, 28 August 2006 (UTC)[reply]

Sorry, lol. But the main problem with Relativity is that there is no direct comparison from the world we know, so it is really difficult even to explain a tiny part of it. Like for instance, the Big Bang. We think of it as a starburst, like during fireworks. But it wasn't like that, because a starburst is a three-dimensional object. Spacetime has at least five dimensions, and because the universe is so massive, and because it was actually creating itself as it expanded (not getting woo-woo, it's just a good way of explaining it), it wasn't expanding into something like all our three-dimensional explosions, and the tremendous mass was curving it as it was expanding, and curving time. It's impossible to describe, because it doesn't exist on the planet Earth. It's kind of like a cross between a donut and a starburst, but... not. Imagine a vehicle creating the highway it's driving on, on an infinitely curved surface, both causing and resisting almost infinite gravity. And travelling close to the speed of light. Along with an infinite number of other vehicles doing the same in every direction. Every direction, including the two or three or more that we have no experience of in our lives. You see the challenge here, to describe it meaningfully? Especially since we have an imperfect understanding of it ourselves. :-) Anchoress 01:50, 28 August 2006 (UTC)[reply]

OK, let's try for a simple example in Special Relativity (or degenerate cases of General): the twins paradox. Suppose you have a pair of twin babies, just born, and you let one float about in space free from any major gravitational effects, and put the other on a spacecraft that accelerates to almost the speed of light, then turns around and comes back. Special relativity says that if you have an inertial frame of reference - one without any accelerations, like the first twin - then while time for you passes at the rate of one second per second, the clocks on things moving very fast relative to you appear to be going slower. So, in this case, the clock on the spaceship seems to have slowed down, to the point that when the twins meet again the one who didn't go anywhere has aged, say, 30 years, while the twin who was on the spaceship has experienced "slower" time, and is still only 1 year old. Confusing Manifestation 02:59, 28 August 2006 (UTC)[reply]

What is the significance of a theory so far away from life - spacecrafts traveling at the speed of light, babies floating about in space, bending time and space and what not. My question is "Had Einstein not postulated this theory, would we have been living our lives differently? If yes, in what ways? If no, why study Relativity at all?" After all, science is meant to be applied some way, right? Shall we, in conceivable future (in any future for that matter), be able to develop a spaceship that travels at the speed of light and prolong our lives?(-: --Mr. Inquisitive 04:19, 28 August 2006 (UTC)[reply]

That's an excellent question, but one I can't answer. If no one had come up with the Theory of Relativity, would anyone's life be different, other than physicists and astronomers? If no one had come up with quantum theory, then the electronics industry wouldn't exist, but relativity?-gadfium 04:51, 28 August 2006 (UTC)[reply]

As a start on an answer, see GPS. General relativity is necessary to calculate the correct trajectories of the satellites. Of course, all sorts of modern physics research, which has its own relevances, depends critically on understanding the relativistic world: particularly particle physics and astrophysics. It's also directly visible in such things as the precession of Mercury's orbit. I'd also suggest just reading the articles for examples of their relevance. Does any of that help? --Tardis 17:04, 28 August 2006 (UTC)[reply]

Relativistic mass is used in solid state physics (and in other things too) Oh and what about nuclear fission /fusion--Light current 22:43, 28 August 2006 (UTC)[reply]

All right, Einstein's Special Relativity in small pieces...

Step 1. The speed of light is not infinite... [experiments] by Galileo established that the speed was very large and subsequent estimates gradually homed in on the answer. We now know this speed to several digits of accuracy (186,285 miles per second).
Step 2. The absence of the ether... The Michelson-Morley experiment was a stupendous feat. Using an extremely sensitive apparatus, Michelson and Morley demonstrated that the Earth could not be moving through a luminiferous aether because, to be consistent with their repeated null results, such an aether would have to always be moving at zero velocity relative to the place where the experiment was occurring. This non-motion would have to be persistent across times of day, months of the year, and so on, where we recognize that at different times of day, the direction of the Earth's motion in its orbit around the sun is (from the point of view of a point on the surface) changing -- 90 degrees between dawn and noon, 90 degrees from noon to dusk, and so on.
Step 3. The need for length contraction... The Lorentz-FitzGerald contraction hypothesis was put forth to explain Heaviside's result that electric and magnetic fields are deformed by motion. This hypothesis also "saved" the null result of Michelson and Morley. In essence, Heaviside says that the faster an electric or magnetic source moves, the more compressed its field becomes in the direction of motion. The contraction hypothesis was a particular mathematical form of that contraction that was consistent with Heaviside's results. A consequence of this form is that the contraction is complete when the motion is at the speed of light. In other words, an electric field source, moving at the speed of light produces an electric field with zero thickness (in the direction of motion).
Step 4. From "mathematical fix-up" to postulate... The Lorentz-FitzGerald contraction hypothesis was specifically proposed for the electromagnetic force by Lorentz in 1904. In 1905, Einstein's paper On the Electrodynamics of Moving Bodies was published. In this paper, Einstein takes it as a postulates that (1) the laws of physics look the same for all (non-accelerating) observations and (2) the measured speed of light is the same for all (non-accelerating) observations. The first postulate is known as Galilean relativity and essentially means that physics is the same everwhere and everywhen. The second postulate is the new ingredient, not contained in classical mechanics and (only) implicitly contained in Maxwell's equations]] of electrodynamics. This second postulate creates the new consequences of Special Relativity. The second postulate directly explains the Michelson-Morley experiment's null result. (Of course there's no difference in the speed of light measured at different times and places; it's always the same because that's just how the Universe works.) Einstein shows that the Lorentz-FitzGerald contraction gives the correct geometry for moving objects -- not just for the electric and magnetic fields as observed by Heaviside, but for all objects and fields.
Step 5. Consequences... The prior body of physics, with this one new postulate and the mathematical description of nature that it provides, explains a number of unexpected consequences.
- Length contraction in the direction of motion -- so now we know that the nucleii colliding in the Relativistic Heavy Ion Collider are nearly zero-thickness, simplifying the collision (because "different parts" of the nucleii all collide at once instead of at "different times", unlike for example a water balloon, where the water at the "back of the collision" must wait a bit before finding out that the collision is even happening).
- Universe contraction -- Switching roles, so that now the experimenter is moving through a "stationary Universe"... If the experimenter is neither accelerating nor being accelerated, the first postulate forces that the two hypotheses "experimenter moving through the Universe" and "Universe streaming past the experimenter" are indistinguishable. Consequent to the second hypothesis, Lorentz-FitzGerald contraction require that the Universe appear to be contracted in the directino of motion. This is observed for muons produced by Cosmic rays. A muon normally only exists about 2.2 μs, which wouldn't normally be enough time for a muon to reach the surface of the Earth form a collision in the upper atmosphere. Practically, we know this because (for example) the AGASA captures such muons. From the AGASA point of view, the muon's time is dilated (see the next consequence) so that the particle lasts long enough to reach the detectors. From the muon's point of view, the Universe is so contracted in the direction of it's motion that it will reach the surface of the Earth in less than 2.2 μs. This (apparently) different description from the two points of view is sometimes taken as a sign of "spookiness" about the theory, but this is not founded. The two descriptions are equivalent, predict the same results and describe the same, coherent Universe.
- Time dilation -- The Hafele-Keating experiment showed that Lorentz-FitzGerald contraction prediction for time was observed. Faster moving clocks record less time passage than slower moving clocks. Global Positioning System calculations correct for this effect (although there is controversy about the necessity of this correction).
- Relative history -- Imagine two particles starting at a point and moving at right angles, say "right" and "up" relative to an experimenter near that point. Suppose the two particles are moving nearly the speed of light. Then, from the particles's points of view, the Universe is contracted in their direction of motion. Note that these two directions of motion are different, so the Universe looks contracted differently to each particle. Imagine two flash bulbs, "above" the experimenter and separated from the "up" particle path by the same amount in the "left" and "right" directions. At some instant, the two flash lamps flash so that their light will strike the "up" particle. From the (stationary) lamps's points of view, their two flashes arrive at the "up" particle at the same time and at the "right" particle at different times because their light will travel the same time (equivalently distance) to the "up" particle and different times (equiv. distances) to the "right" particle. From the "up" particle's point of view, the two lamps are a little bit ahead of it, moving towards it rapidly and the two lamps seem to flash simultaneously. From the "right" particle's point of view, the two lamps are off to its side and the light from the "right" lamp will arrive before the light from the "left" lamp (because the distances to the lamps are different). So the two lamps do not seem to flash simultaneously. Consequently, the notion of "simultaneous" is not a fundamental notion and depends strongly on the motion of the observer of the events.
- Total energy -- Newton's equation $E=mv^{2}/2$ would predict that the energy of an electron moving at the speed of light (an unphysical hypothesis) is about 0.5 MeV. However, Betatrons produce electrons with energies up to 300 MeV, so Newton's equation is not the whole story. Einstein's theory gives $E={{mc^{2}} \over {\sqrt {1-{{v^{2}} \over {c^{2}}}}}}$ which we may expand as $E=mc^{2}+{\frac {mv^{2}}{2}}+{\frac {3mv^{4}}{8c^{2}}}+{\frac {5mv^{6}}{16c^{4}}}+\dots$ . The first term was new, indicated a component of energy independent of the motion of the object, and provided source material for movies, posters, and T-shirts. This is commonly known as rest energy (and is a component of the energy of nuclear reactions). The remaining terms do depend on the velocity. The first of these it the expression given by Newton and the rest are high-velocity corrections. For the Betatron, these correction terms predict the additional observed energy.
Step 6. Integration... The upshot is that at high speeds, the Universe is not as familiar as we might think from our personal vast experiences at low speeds. That the speed of light is the ultimate speed limit for objects to move of fields to propagate disturbances produces changes in the apparent size of moving objects, the apparent thickness of the moving Universe, the rate of clocks on moving objects, the rate of clocks in the moving Universe, the energy required to accelerate an object to high speeds (or the energy of collision with pieces of a rapidly moving Universe), and fusion and fission can release huge amounts of energy, are all predictions of the special theory of relativity. These effects are observable. Some are corrected for in real engineering systems and others are the basis of the systems (e.g. nuclear reactors). -- Fuzzyeric 05:51, 3 September 2006 (UTC)[reply]

hmm another wierd question..

hi again,

I have heard that a dead animal weighs lesser than the same creature when it was alive..why and how?thanks

Anne Ty

At first it will weigh the same (ignoring the small weight of the air in the lungs). But it will weigh progressively less and less as it dries out, leaks, gets nibbled, and rots, until there is nothing left.--Shantavira 11:25, 27 August 2006 (UTC)[reply]

By Archimedes' principle the air in the lungs does not contribute to the weight registered on a weighing scale. --Lambiam ^Talk 12:23, 27 August 2006 (UTC)[reply]

What of the way of "weighing". What would a beam balance show? According to our article it measures mass, and the dead animal - without lung air - should have less mass. And in "normal talk" a person would still talk of "weight". Would the balance show that? --Seejyb 17:00, 27 August 2006 (UTC)[reply]

A beam balance definitely measures weight. It doesn't know what's pushing on it. Melchoir 17:54, 27 August 2006 (UTC)[reply]

I expect the questioner is asking about something like this, which should answer the question. digfarenough (talk) 17:45, 27 August 2006 (UTC)[reply]

I have to carry out experiments on this subject by placing a living animal in one pan of a balance and the same individual, in a dead state, in the other pan. However, problems have arised every time, preventing me from completing the experiment. For some reason, when I look back at the first pan, that animal has died, jumped over to the second pan or (most often) both. —Bromskloss 21:50, 27 August 2006 (UTC)[reply]

Yup, I've objected at the weighing scale article to the use of the word "mass". Now for half of the world's school chemistry textbooks. --Seejyb 22:27, 27 August 2006 (UTC)[reply]

If souls exists and animals have souls too, and souls weight something and the soul parts with the body after death, then your animal is lighter. Good ol'Occam would shiver with that. -- DLL ^{.. T} 18:26, 28 August 2006 (UTC)[reply]

Er, yes. Your point being....?--Light current 22:34, 28 August 2006 (UTC)[reply]

See also Duncun MacDougall, and 21 Grams, the film named after his supposed result. Confusing Manifestation 00:29, 29 August 2006 (UTC)[reply]

Largest Cargo

I'm curious as to the largest object ever transported over an ocean/sea. I'm assuming it would be on a large ship. I know large cranes are shipped around the globe, but I don't know any specifics. 202.180.120.220 11:30, 27 August 2006 (UTC)[reply]

I'm too lazy to check, but read up on the Big dig. I know the concrete for the underwater portion was poured in a quarry somewhere and the huge pieces were submerged whole; at the time it was happening (according to Extreme Engineering or wherever I saw it), they were the largest objects ever transported. Anchoress 11:37, 27 August 2006 (UTC)[reply]

It might have been the Antonov An-124 transporting the Obelisk of Axum. — [Mac Davis] (talk) (Desk|Help me improve)

That was only 100 tonnes... You want things like the Blue Marlin for sheer capacity - something like 60-75,000 tonnes. Shimgray | talk | 16:20, 27 August 2006 (UTC)[reply]

Does iceberg towing / steering count? Not that I have numbers on the largest iceberg to be moved by humans... surely the info is out there if you look hard enough. Melchoir 18:05, 27 August 2006 (UTC)[reply]

I don't know if this counts as cargo, but the (one of the?) largest man-made object(s) ever transported is reputedly the Troll A platform which weighed 650,000 tonnes when it was towed but has a ballasted weight of 1.2 million tonnes. The Jahre Viking/Knock Nevis can carry 560,000 tonnes of cargo giving it a total (full) displacement of about 648,000 tonnes. --Yummifruitbat 18:40, 27 August 2006 (UTC)[reply]

How about the Saturn V rocket? 3,038,500 kg! The Hellespont Fairfax is 442,470 tonnes unloaded. Beat that!— [Mac Davis] (talk) (Desk|Help me improve)

You've got your kilos and tonnes mixed up on the Saturn, that's only ~3000 tonnes. The Fairfax has a deadweight of 442470 tonnes, that's the cargo/fuel/crew/etc. capacity, not the empty weight. Fully loaded displacement is apparently 509,000 tonnes... so the Knock Nevis beats it. --Yummifruitbat 19:53, 27 August 2006 (UTC)[reply]

I always mix up the different "-weight"s. Thanks. Kilos and tons? It said that many kilograms, do you mean to say I should have converted it to tonnes? I'm such a failure. — [Mac Davis] (talk) (Desk|Help me improve)

The question reads 'largest', not 'heaviest'. And of course any ship is likely to be larger than its cargo. There is a list of List of the world's largest ships. But there is also this story about a Chinese emperor who once decided to have a look at the world and had a humungous ship built, as big as a city. After sailing as far as Aftrica he decided the world wasn't interresting enough and had the ship destroyed. Or so the story goes. DirkvdM 08:57, 28 August 2006 (UTC)[reply]

Isn't there a size limit on wooden ships, any larger and they would collapse under their own self weight? Unless the ancient Chinese had stainless steel, that is... — QuantumEleven 12:24, 30 August 2006 (UTC)[reply]

Long-term Effects of Fasting On The Brain

How long must one fast in order to effect permanent damage to the brain, and what is the nature of such damage?

How much brain damage were you looking to cause? But seriously, unless there is an underlying health problem that fasting could exacerbate, brain damage would not be likely until one was seriously underweight, like perhaps 10 or 20% below normal. Many people starve themselves almost to death without ill effects to their brains (although damage to other organs like the kidneys and heart is common). Damage comes from the effects of dehydration and electrolyte imbalance, including thrombosis, seizures, edema, etc. Hope that helps. Anchoress 23:36, 27 August 2006 (UTC)[reply]

If you're a coffee drinker, you might experience some minor withdrawal by the end of your fast--71.247.243.173 14:11, 28 August 2006 (UTC)[reply]

I saw on TV once the fact that in prologed fasting, the body first uses the fat, than the muscle, and finally devours the brain--Light current 22:30, 28 August 2006 (UTC)[reply]

Telephone numbers

what is the purpose of the + sign in telephone numbers? explain in as much detail/background info as possible plz. 21:08, 27 August 2006 (UTC)

The + indicates that the following characters are not the format for local dialling, but are a universal representation beginning with the country calling code. Software (and people) convert a number to the form required in a particular locale. See E.164 and international call prefix. Peter Grey 21:30, 27 August 2006 (UTC)[reply]

Stroke risk.

My mum had a minor stroke a few years back. Since then she's been on water tablets and blood pressure tablets. But on friday she ran out, and can't get any more till tuesday. She say's shes getting a "Thick head" like she used to when she climbs stairs. Is there much risk about her not getting her medication for these few days?

Unfortunately, that symptom is not very helpful without more clinical information. If she is not taking her blood pressure medications, she could certainly have a high enough blood pressure to cause some troubling neurologic symptoms - stopping some blood pressure medications can lead to severe withdrawal-related high blood pressure. If she's having symptoms, she should have her blood pressure checked. InvictaHOG 00:02, 28 August 2006 (UTC)[reply]

Monitor her BP constantly. If it gets bad, take her to the nearest Emergency Room and they will give her meds. StuRat 08:54, 28 August 2006 (UTC)[reply]

In the US, most pharmacists will sell a person enough pills for chronic conditions such as diabetes or high blood pressure to prevent a need to go to the ER for a couple of days while the doctor phones or faxes a new prescription to the pharmacy. Most pharmacies will call the doctor to get the prescription refilled. Try other pharmacies until you find a good and caring pharmacist who will sell enough meds to last her until Tuesday. Why risk a stroke? Good luck. Edison 15:22, 28 August 2006 (UTC)[reply]

secondary dysmenorrhea

In 1999, I had very painful menses. I would often faint due to the pain (vaso vagal response). I had other symptoms as well. My breasts grew and were very painful. I had a very stong smell in my urine. An ultrasound performed in March 1999 showed what was believed to be a cyst. My gynecologist was not concerned and did not think it had anything due to my other sympoms. I had used Motrin previously for relief of cramps. I seemed to get the opposite effect. My bleeding slowed down and the pain increased. I thought that perhaps it slowed down the prostoglandins to the extent that I was not able to shed the lining of the uterus. My gynecologist prescribed narcotics for the pain which worked quite well. Of course when the narcotic wore off, I experienced excruciating pain again. This went on for months. I was cranky. I was nauseated. I kept dreaming that I was having a baby. I told my partner that I felt like I was pregnant.

In December of 1999, I adjusted a patient (I am a chiropractor). I had excruiating pain and fainted. I had bled through my pants and onto the carpet. I was taken to a hopsital by way of ambulance leaving a puddle of blood behind me. I was told that I had a mass on my follopian tube and as I adjusted the patient, my fallopian tube along with the mass was torqued causing the pain.

I had suregry to remove a dermoid cyst tat was larger than my uterus. My surgeon shared the photos with me. One of the doctors on my case said that he wished he had done a pregnancy test. The fowl smell in my urine was due to the Humane Growth Hormone.

My breasts slowly returned almost to their original size. My urine didn't have a fowl odor. The nausea was gone as was my crankiness. What an ordeal.

It is now August of 2006 and I am having the severe cramping along with the vasovagal effect. I took motrin which I had been taking for cramps. This time, like before, my pain has worsened. The bleeding has stopped. I don't seem to have any of the other symptoms that I had with the dermoid cyst.

What exactly causes my pain to worsen if I take motrin and why does it halt the shedding of the uterus?

Respectfully, 4.88.31.98 23:46, 27 August 2006 (UTC)[reply]

I think to find that out, we'd need to be able to figure out why you have the cramps in the first place. It sounds like you need to revisit your gynecologist. Another ultrasound may be in order or at least a blood test (I'm not sure if it is human growth hormone or human chorionic gonadotropin you mean to refer to!) InvictaHOG 00:09, 28 August 2006 (UTC)[reply]

I'd find another gynecologist though than the one who was not concerned. --Lambiam ^Talk 10:03, 28 August 2006 (UTC)[reply]

Your symptoms sound like an ectopic pregnancy or perhaps an ectopic psuedopregnancy.StuRat 00:25, 28 August 2006 (UTC)[reply]

Do suppose this could be due to a subluxation of your spine? Maybe another chiropractor could give you a spinal adjustment. Or you could call a good gynecologist. Edison 15:25, 28 August 2006 (UTC)[reply]

Reminder: If requesting medical, dental, or legal advice, please consider asking a doctor, dentist, or lawyer instead. With free advice, you get what you pay for. - Cybergoth 17:33, 28 August 2006 (UTC)[reply]