Wikipedia:Reference desk/Archives/Science/2006 November 19

= November 19 =

Cell phone minutes
I wonder if the FCC is able to regulate the maximum amount of regular and anytime minutes. My cell phone rates are going up in february but i am keeping the same plan. Any idea if the FCC deals with this or the company itself. My company does not explain it well. They just sent me emails and text Msg's.--Biggie 00:57, 19 November 2006 (UTC)


 * You are free to buy any plan you like or switch companies and keep the same phone. But thank God the FCC doesn't regulate rates or you would be paying a lot more. Tbeatty 01:33, 19 November 2006 (UTC)


 * On the other hand, many of the highly deceptive practices which apply to cell phone plans, but didn't to land lines, would have been stopped with proper gov regulation. For example, the area of coverage is often only vaguely described, and subject to change.  Thus, after signing up for a plan, you can find out all your calls will have an excessive roaming charge added.  You could cancel, but they have huge cancellation fees, too.  I use a "pay as you go" cell phone so that type of thing can't happen to me. StuRat 01:40, 19 November 2006 (UTC)

Thanks for the info.--Biggie 03:52, 19 November 2006 (UTC)

Uranium and birth defects
If uranium does cause birth defects, would those be passed on to the next generation or not? How would this effect long-term survial? If a human life is worth $7,000,000 then how much is the amortized cost of using uranium weapons? 208.54.15.1 05:44, 19 November 2006 (UTC)


 * Radiation, such as that from radioactive uranium, would chiefly cause birth defects by causing mutations in the DNA. Usually the mutations seen at birth would result from mutations in the germ cells, the sperm and egg, of the parent. This would then be passed onto all cells in the offspring, including its germ cells, so would then subsequently be passed on to its offspring. Depending on the extent of the genetic damage, obviously it could have consequences for long-term survival, but this also depends on how many people were affected, as well as many other issues. Re the costs, that's a bit of a philosophical area that I'll let others consider. --jjron 06:04, 19 November 2006 (UTC)


 * You mean putting a price on human life? So where do I go to pay $7 million to raise the dead? --Wirbelwind ヴィルヴェルヴィント (talk) 06:08, 19 November 2006 (UTC)


 * Actually, $7m is somewhat of an overestimate. See Value of life. GeeJo (t)⁄(c) &bull; 05:25, 21 November 2006 (UTC)


 * The radioactivity from uranium is very slight, because of its extremely long half life. Long half lives mean that not much of the stuff is undergoing decay at any given instant. That doesn't mean it's impossible for radiation from uranium to cause birth defects, but I think it's a very low risk compared to other causes.
 * Now, whether the chemical properties of uranium might cause birth defects is quite another question. As I understand it, the largest risks to human health posed by exposure to uranium relate to chemical toxicity, not radiation. --Trovatore 06:14, 19 November 2006 (UTC)


 * Ah, good point. I took the question as being related to radiation, moreso than just uranium. Presumably if the chemical effect was to damage the DNA it could cause the same chain of events, but I don't know if it does cause the genetic mutations. --jjron 06:51, 19 November 2006 (UTC)

By "uranium weapons", do you mean nuclear weapons or depleted uranium shells and armor ? Obviously, the risk from using nuclear weapons is far greater. StuRat 06:56, 19 November 2006 (UTC)
 * Not if you're a member of UNIFIL on duty in Lebanon. --Lambiam Talk  13:42, 19 November 2006 (UTC)

Uranium mentions teratogenic effects but not the cause. If the effects are from chemical toxicity to the developing embryo (side note: most teratogenic effects develop in embryos, not in later fetal stages) they likely won't be heritable. Chemical teratogens generally act on the development process, not on the genes of the embryo. --Ginkgo100 talk · e@ 15:03, 19 November 2006 (UTC)

sodium hydroxide
I'm trying to find out a bit about caustic soda (like drain cleaner) but 'science speak' goes over my head a bit. In simple terms... if some caustic soda/drain cleaner was used a year ago, and not cleaned up properly afterwards so some residue remained, what properties would it now have ie how caustic/alkaline/dangerous(to skin etc)? Thank you. Twosparrows 05:56, 19 November 2006 (UTC)


 * It's toxic, and that's no lye.
 * Getting it wet again,
 * makes it caustic,
 * to both the skin and eye.
 * StuRat 06:46, 19 November 2006 (UTC)


 * It's hard to say for sure. After a year lots of other things could have happened. If was outside it would have been rained on etc, which would help clean it up. If you've been walking through the area, even if inside, that would help 'clean' it as you would be gradually spreading the stuff around and moving it away, mixing in other things etc. If it was in a drain/sink that's being used that would wash the area. It will also gradually possibly react with moisture in the air, etc. I would guess given all the unknowns that it's possibly somewhat less dangerous than a year ago, but I'd still get it cleaned up properly. --jjron 06:59, 19 November 2006 (UTC)


 * I think (and Sodium hydroxide confirms) that it absorbs CO2 from the air, gradually changing into harmless sodium carbonate. —Keenan Pepper 21:43, 19 November 2006 (UTC)
 * It will change into sodium carbonate - but that is not harmless - it's almost as caustic as Sodium hydroxide. And if you've ever got sdoium carbonate into a cut you will know it can also be painful.
 * Well, if you get it "into a cut" it'll hurt, sure. But you can touch it with your skin and you'll be fine. —Keenan Pepper 17:07, 20 November 2006 (UTC)

Okay, next question... water causes sodium hydroxide to heat up, yes? How about sodium carbonate? Twosparrows 11:29, 21 November 2006 (UTC)

How many children can my wife and I have?
Lets say totally hypothetically my wife (which I don't have yet) and I want to have a lot of kids. Could we harvest all the eggs from her ovaries and use in vitro fertilisation to fertilize each one and then put them into a large number of women who will act as third party reproducers? According to this page a woman has 400,000 eggs. Any ideas about the technical feasibility of this? Ed Dehm 05:57, 19 November 2006 (UTC)


 * I don't think that brochure is correct. A human female should only have about 300 ovum at birth, and one is released every 28 or so days. "A man manufactures about 400 billion sperm cells in his lifetime. "A woman will avail about 300 ova in her reproductive years." and "Each Ovary contains about 400,000 PRIMARY FOLLICLES, which are clusters of cells surrounding a single ovum (egg). 2. During her lifetime fewer than 500 Ova (Eggs) will actually be released, averaging one egg about every 28 days. So the most kids you can have with one wife is about 300-500. --Wirbelwind ヴィルヴェルヴィント (talk) 06:16, 19 November 2006 (UTC)


 * Isn't hypothesising fun. I'm going from memory here, but the 400,000 sounds reasonably accurate for what a girl is born with, by the time she reaches sexual maturity the number has declined substantially, I can't remember the actual number, but I think it's in the tens of thousands. The 300 or so Wirbelwind mentions is the number actually released over her lifetime. Now back to your question. Theoretically this could be possible, but if you want the 400,000 you better chose your partner at birth and harvest the eggs then (see above), presumably this raises some moral and ethical issues though. Current IVF is far from 100% successful and there could be lots of other problems with harvesting all the immature egg cells and presumably trying to store them for some years. Then I hope you're very rich, to pay for all the medical costs, all the surrogate mothers, and to raise whatever number of kids results. And please think about your environmental impacts of having so many children; this should not be encouraged. --jjron 06:37, 19 November 2006 (UTC)


 * Here's a better article about ovaries. Not all 400,000 of those are fertilizable, so a woman will only have 300-500 fertilizable cells per lifetime. So unless you can scientifically make all 400,000 grow into fertilizable cells, I stand by the 300-500 children. --Wirbelwind ヴィルヴェルヴィント (talk) 06:53, 19 November 2006 (UTC)


 * Valid point, but since we are just hypothesising, I'm guessing that in our imaginary world we have the technologically to make them all fertilisable. --jjron 07:04, 19 November 2006 (UTC)


 * And if we are really speculating, just clone the children in the eggs and instead of jsut surrogate wombs, you can use surrogate embryos and the number becomes unlimited. --Tbeatty 08:47, 19 November 2006 (UTC)


 * When fertility drugs are administered, for invitro fertilization or other techniques, there are 4 or 5 mature eggs per ultrasound every month. Figure 30 years of ovulation, at 28 days per cycle and you get 391 cycles. 4 eggs per cycle yields about 1500 mature eggs.  Some college girls if they are smart and beautiful, sell their eggs for 10,000 a pop to couples who are infertile or who want to be surrogate parents for some other reason. I would think there would be some physiological penalty for such overstimulation. I wonder what they do in this regard with champion female racehorses or dairy cows, to make their value more comparable with  stallions or bulls. Strangely, guys in med school only get about $100 for a sperm donation given for artificial insemination. Some finish med school with dozens of children out there they don't even know.Edison 15:34, 19 November 2006 (UTC)


 * I don't find that strange at all, considering it's easier for males to donate and males produce millions quite frequently. --Wirbelwind ヴィルヴェルヴィント (talk) 17:16, 19 November 2006 (UTC)


 * So it looks like if I have a wife who is a little past puberty then I would be able to get 300-400 fertilizable eggs out of her. The question then is how many of those would successfully grow into babies inside the surrogate mothers.  This could be done in "batches" of like 50 at a time, every 2 years so it requires with fewer surrogate mothers. Ed Dehm 20:58, 19 November 2006 (UTC)


 * Actually, no, because you will need to wait 28 or so days before the second egg is fertilizable. --Wirbelwind ヴィルヴェルヴィント (talk) 23:22, 19 November 2006 (UTC)


 * I always thought that with sperm, there is quite a bit of 'natural selection' going on in the race to the egg, as in, most males produce a certain amount of blank 'sperm' the 'differently able' kind, with 2 tails or whatever ;), and a certain amount of healthy ones, strong swimmers and what ever that make it to the finish line, only one of them lucky enough to be THE ONE. Even then, things can go wrong, a certain number of pregnancies don't make it past the 1st few weeks, the body naturally aborting the process because something was not quite right. So, are eggs also susceptible to imperfection? There isn't as much redundancy as sperm so I imagine it is a lot less but I can't imagine every released egg is perfect? Vespine 00:07, 20 November 2006 (UTC)

Dogs
Why does a dog’s back leg kick if you scratch him in the right place on his stomach? Thanks! 71.112.91.149 06:23, 19 November 2006 (UTC)
 * Reflexes. --jjron 06:41, 19 November 2006 (UTC)
 * Specifically Scratch reflex. Look at the last reference,  Seejyb 10:37, 19 November 2006 (UTC)

Parachutes
Will the bigger parachute fall faster or slower ?


 * Slower. see terminal velocity--Light current 11:39, 19 November 2006 (UTC)

Rocket Engines
If a spacecraft where built in space not limiting its mass, what kind of engine could be built that is possible with todays technologies to allow that space craft to make it to Jupiter and back in Five years?


 * And back? Why would you want it to come back? If scientific research is the objective (what else?) then it makes more sense to leave the spacecraft out in space (near Jupiter or moving on) and keep on sending info back to Earth. The only reason for it to come back would be that there are humans aboard (which seems pointless) or to bring something else back. Are you thinking of rocks from the rings or something? Also, it depends on when you send it. Space craft that go so far usually make use of gravitational slingshots, which depend on the relative position of the planets. Or is it your objective to not have to depend on that? Then the rocket would have to be very expensive, since all the fuel needs to be transported up into space. Which is sort of begging the question. The only alternative I can think of is using Solar wind, but that would make is very slow, unless the sail is huge (I think). DirkvdM 09:52, 19 November 2006 (UTC)


 * See Project Orion (nuclear propulsion), and more generally Spacecraft propulsion. --Lambiam Talk  13:54, 19 November 2006 (UTC)


 * If we ever built the full-on Project Orion ship, we could do a Jupiter mission in months, not years. --Robert Merkel 07:12, 20 November 2006 (UTC)

If you don't limit the mass (which is, of course, an absurd assumption), a standard rocket would work fine, it would just need to be absolutely huge to carry sufficient fuel to accelerate to the needed speed, decelerate at Jupiter, then accelerate again, then decelerate back near Earth. If you just wanted to slingshot around Jupiter, a smaller rocket would work, but you would fly by at a rather high speed. StuRat 06:19, 20 November 2006 (UTC)

How do parafin heaters work?
Hi,

My nephew has been posed this rather strange question by his teacher. I can't seem to find anything on the internet that answers this question. Any help would be appreciated.

Thanks!Dave

See paraffin, paraffin heater, kerosene lamp. See also portable stove--Light current 11:42, 19 November 2006 (UTC)


 * Searching for kerosene (as opposed to paraffin) could yield useful information, such as this site on kerosene heaters. Seejyb 12:39, 19 November 2006 (UTC)


 * Yes, you want kerosene heater, not paraffin heater.--Shantavira 15:11, 19 November 2006 (UTC)


 * So maybe a page on Paraffin heater could redirect to kerosene heater? 8-)--Light current 18:29, 19 November 2006 (UTC)

Why do cockatoos do this?
Just found this pic in the (probably soon to disappear) Cockatoo beak hanging article. Opinions? I know that this is a pet bird but does anyone have any suggestions as to why a cockatoo might need to do this in the wild? That's one strong beak - I wonder how many humans would be capable of supporting their own bodyweight with their jaws? --Kurt Shaped Box 10:01, 19 November 2006 (UTC)


 * sorry to be so cynical but I think they do this for nuts, sunflower seeds, a bit of millet, maybe a new mirror or swing in their cage etc etc


 * According to the Guiness Book of Records, humans can lift motorbikes with their teeth, so it's not unreasonable that a human could lift their own weight with their teeth. La  ï  ka  13:06, 19 November 2006 (UTC)


 * You're probably pretty close to the truth. It can often be the case with owning an intelligent bird such as a parrot or corvid that the bird trains the human to behave how it wants it to behave, rather than the other way around. My lovebird used to play me like a fiddle - be it clowing around and acting cute for treats or screeching and biting to get attention/her own way. Once they figure out that the big, lumbering, flightless creature they live with is not a threat to them, they know that it will happily cater to their every whim if prompted sufficently. --Kurt Shaped Box 13:48, 19 November 2006 (UTC)

Cockatoos swing and hang because this behavior is beneficial in the wild, presumably for getting around in trees, reaching food, and possibly for social reasons (like displays). Generally speaking, cockatoos in captivity do it because they have an instinct for it just like their wild cousins. In my experience they often do it with humans, particularly those they are bonded to, for affection and head scratches, not just for food. Cockatoos are very social creatures and, like dogs and humans, can have purely social rewards. --Ginkgo100 talk · e@ 14:54, 19 November 2006 (UTC)


 * Hmm, a less wordy way to say all of the above is that they do it because it is fun. =) --Ginkgo100 talk · e@ 14:55, 19 November 2006 (UTC)
 * I've seen them get around trees in the wild, and it is a very useful thing to swing from the beak. They are too heavy to just fly from brach to branch (too much energy), and they have no arms. --liquidGhoul 15:16, 19 November 2006 (UTC)


 * So basically the beaks is used as a third leg (like a prehensile tail)?

There is a circus act where a woman hangs from her teeth on a twirling rope. I wouldn't recommend this, but we can support our own weight with our teeth if we really need to. StuRat 06:13, 20 November 2006 (UTC)

Articles on Roadway Lighting systems
I a really stuck as to how i can get articles on roadway lighting systems so as to give a talk on this topic.I would be very grateful if anyone could give me more information on this topic be it good or bad in relation to recent technologies so that i can put up a solid defence.Thank and i am waiting patiently for a response
 * Do you mean street lights? –Mysid ☎ 10:20, 19 November 2006 (UTC)
 * does that include traffic lights?


 * For North American lighting systems, check out The Illumination Engineering Association of North America. For one specific new application of technology to street lighting, check out this abstract on LED based street lights.  That should give you a good starting point for further research.  192.168.1.1 9:35am, 19 November 2006 (PST)

Wisdom tooth extraction...
So, I've got to have one pulled. It's at the top on the right-hand side. The tooth has gradually crumbled away over the years and there is only a small stump left above the gumline. I've heard lots of horror stories about people having wisdom teeth extracted (I've had a few teeth removed in the past but I've been told by several people that the WT are very 'difficult' - my dentist told me that it's not much of a big deal, though I don't know if she was just trying to put me at ease). Anyone have any experience with this? What sort of procedure am I looking at? Will they have to put me under? I'm just looking for a general idea, really. --Kurt Shaped Box 16:59, 19 November 2006 (UTC)


 * It depends on the tooth really. I had all four of mine removed. I didn't get any laughging gas either, just the 12 shots of anesthesia, so you might only have 3. They gave me prescription ibuprophen afterwards, but I never took one because after the anesthesia wore off, it felt only a little sore. Another friend had it removed and his was swollen but didn't hurt much. My sister also had hers removed, but hers was swollen for two days and was supposedly painful for two days. So it really depends on the tooth, but since you are only removing one, it shouldn't have as many problems, as long as they're able to normally extract your tooth which is barely above the gumline. --Wirbelwind ヴィルヴェルヴィント (talk) 17:10, 19 November 2006 (UTC)


 * Like Wirbelwind said. It's unpleasant, rather than horrible. And it's unpleasant in ways that will give you amusing stories to tell afterwards. - Nunh-huh 17:12, 19 November 2006 (UTC)


 * Thanks guys. I've just got to wait a week and a day now... ;) --Kurt Shaped Box 18:26, 19 November 2006 (UTC)


 * Good luck with that. =) --Chickenflicker---♣ 18:28, 19 November 2006 (UTC)


 * Its only tricky if the wisdom tooth has a forked root (like mine had). Dentist took X ray B4 attempting it. The procedure with a forked root is to cut the tooth in half with the drill and then to extract each half separately with the pliers! Simple. Also, youll only need local anaesthetic (3 / 8-)--Light current 19:07, 19 November 2006 (UTC)


 * BTW Is laughing gas still used? I havent had gas for years. Neither have I had a really good laugh! Which reminds me of a joke... NO better not--Light current 20:56, 19 November 2006 (UTC)


 * They tell us that wisdom teeth become impacted because our modern jaws are too short to accomodate the teeth that our prehistoric ancestors used to grind their hunter/gatherer food. So the unfairest thing I have read lately is that they found the jaw of a female who lived 30,000 years ago or so who had an impacted wisdom tooth, the earliest on record. Edison 22:54, 19 November 2006 (UTC)


 * My teeth aren't impacted. I just have really bad teeth. :) --Kurt Shaped Box 23:10, 19 November 2006 (UTC)


 * I had all four taken out in one go, one badly impacted and the other pretty close to being impacted. I had premed oral valium and during the thing had Demerol IV (enough to put me almost to sleep, but not quite). I have no memory of the three regular ones being pulled, but they had to smash the impacted one and pull out the chunks (which I do, vaguely, remember, including a jolt of pain).  This was followed by a short course of antibiotics. The jaw was entirely immobile for more than a day afterward, and I lived off milk for two days.  I couldn't chew for about four days. I icepacked the jaw continually for the first day, and had no bruising and only very minor swelling.  There was gauze in my four sockets to staunch any bleeding, and I took that out at the end if the same day. Most common complications are infection, penetration of the sinus (where pulling a tooth makes a hole between the maxillary sinus and the mouth - if that happens you go back in and they sew it closed), and (quite rarely) a broken jawbone.  I had none of these.  Don't go to sleep for several hours after the operation (mine was about 7.30 in the morning, so I was rather sleep deprived, and the valium made that worse) - you can swallow your tongue.  They tell you to regularly wash your mouth with salt water, which is a joy (there's inevitably some blood in your mouth, and the remants of whatever you've been drinking or trying to eat, and you're in no position to brush your teeth).


 * Pros and cons:
 * pros:
 * demerol is an opioid; I felt very nice for the several hours afterward
 * the hygene if the surrounding teeth and gums improved greatly (it turns out I really couldn't get the brush far enough back to brush them properly)
 * bar the jolt of pain during the procedure, I had no pain worse than a dull ache. They also prescribed a dozen vicodin, but I didn't take any of these (just ibuprofen to lessen the swelling).
 * cons:
 * I used the several days at home to rent videos that my girlfriend refused to see. This was good in theory, but Stir of Echoes and particularly The Bone Collector weren't smart choices (stuff about murder and torture didn't sit well, for fairly visceral reasons).  And The Omega Code wasn't a good choice because it was so utterly and spectacularly awful.
 * After two days with nothing in your mouth but bloody gauze and full fat milk it feels like you've got a goat in there
 * It's boring (can't really work, can't really go anywhere, can't really eat, but really not sick or weak or tired)
 * I had to sleep on my back
 * -- Finlay McWalter | Talk 23:22, 19 November 2006 (UTC)


 * I would not worry either. The last wisdom tooth I extracted on a patient was completely painless... I did not feel a thing. :-P Fret not. It should not be too bad.  Make sure to stay away from cigarettes after an extraction! - Dozenist  talk  23:44, 19 November 2006 (UTC)


 * How is it done if there is very little left above the gum surface? Does it invlove drilling and tapping (as in screw threads)?--Light current 01:22, 20 November 2006 (UTC)


 * Usually, you reflect the gingiva away and use a handpiece (otherwise known as a drill) to remove the bone around the tooth (particularly a lower tooth) if there is too little exposed in the mouth. Then again, there are many ways to skin a cat. - Dozenist talk  03:23, 20 November 2006 (UTC)


 * Ooooo! That sounds quite nasty and painful Kurt! 8-)--Light current 03:57, 20 November 2006 (UTC)

Having any tooth extracted is no fun, but as alluded to above, the wisdom teeth (3rd molars) are known for being impacted, which is what happens when, in breaking through the gum, they are located partially under the already existing 2nd molar. That often requires surgery. If not impacted, wisdom tooth removal is no worse than that of any other molar. B00P 08:14, 20 November 2006 (UTC) (All four impacted.)


 * But you actually neglect to mention the problem of bifurcated roots. THis necessitates mor than just a quck heave ho!--Light current 16:39, 20 November 2006 (UTC)

Casimir attractive or repulsive?
I know this may have been asked before but it doesnt seem to be on the casimir effect page at all. Sometimes the casimir effect is called an attractive effect and other times a repulsive effect. But since, and tell me if this is wrong, the two plates are pushed together because there is more radiation pressure from the zero-point energy field on the outside of the plates than on the inside of the plates. If the effect is dealing with pressure how can the force be attractive exactly? pardon my ignorance Robin
 * I suppose it's called attractive because the two plates are attracted together. It is true, as you say, that the mechanism is really reduced radiation pressure between the plates, so it might be more accurate to say they're pushed together. -- SCZenz 20:21, 19 November 2006 (UTC)

Hmm i read somewhere that it seems similar to an effect in water, so in essence it is kind of both Robin

Is cannabis really good for asthma and tuberculosis?
I've just been listening to a Peter Tosh song ('Legalize It', for anyone that cares) where he claims that this is the case. This is complete and utter BS, right? --Kurt Shaped Box 18:30, 19 November 2006 (UTC)


 * See: Medical cannabis. Cannabis has a variety of physical and psychological affects that are claimed to have medically beneficially effects, ranging from acting as a pain killer to helping prevent glaucoma.  Use in the treatment of asthma  has some medical history, and I wouldn't be surprised if its anesthetizing aspects can be beneficial in the treatment of the symptoms of tuberculosis (though not necessarily competitive with modern medicines).  As far as I know, marijuana is not regarded as a cure for any disease, but people dealing with chronic pain and other symptoms may choose to use the cannabis high as a form of symptom management.  Dragons flight 21:23, 19 November 2006 (UTC)


 * Remember.. Peter Tosh is NOT a doctor. Personally I find it hard to believe that smoking ANYTHING is actually "good" for asthma, but I too am not a doctor!


 * Right, smoking is bad for asthma. It is possible that eating cannabis might help asthma influenced by stress or anxiety.  Tuberculosis must be treated with long-term antibiotics.  -THB 00:43, 20 November 2006 (UTC)


 * His name seems to give the game away doesnt it? Tosh 8-)--Light current 02:39, 20 November 2006 (UTC)


 * Perhaps if their names were Puff the Magic Dragon and THC. StuRat 05:59, 20 November 2006 (UTC)


 * Smoking itself doesn't sound very good for athma, but maybe the beneficial stuff in cannabis needs to be applied directly to the lungs. One option might be a vaporiser. The problem with controversial subjects is that there is so much bullshit flying around that it is hard to find any reliable info. DirkvdM 11:18, 20 November 2006 (UTC)

I've heard that it's made into a tea (add hot water to leaves etc) for chest problems etc - but I really don't want to encourage you.


 * Yeah, that might've been what he was talking about. I just had this vision of asthmatics and TB patients sat around smoking big fat spliffs whilst hacking and wheezing between draws... --Kurt Shaped Box 12:48, 20 November 2006 (UTC)