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March 15

How did people thousands of years ago know that fruits and vegetables are healthy?

Most of the foods that we eat today that are known to be healthy using the methods of modern science, have existed for many centuries. How did people know that e.g. carrots are healthy (the name for carrot in certain Asian languages translated literally into English is "strong body")? Count Iblis (talk) 00:15, 15 March 2013 (UTC)[reply]

Not really a proper answer, but... I'm not sure where the carrot example traces back to, but for example Dioscorides collated data about "normal" fruits and vegetables as well as more medicinal herbs. Ancient herbal knowledge was extensive, but shows certain limitations - especially, they don't seem to have had any conception of how to cure cancer or even whether their treatments caused it. For example, Dioscorides knew about yew, but he didn't know about taxol, and aristolochia, alas, continues to cause trouble to this day. From this limitation, I would suspect that the knowledge must have come from fairly short term trial and error testing and/or a lot of very careful observation. Wnt (talk) 00:31, 15 March 2013 (UTC)[reply]

Chimpanzees and rats and many other mammals eat fruits and vegetables. Do you really think it required a human cortex to start eating them? alteripse (talk) 01:01, 15 March 2013 (UTC)[reply]

By taking a little nibble on unfamiliar foods. Poisonous foods generally wouldn't kill them from just that. However, if they tasted horrible or made them sick, then they'd avoid those foods. If the nibble turned out okay, then next time they might try a bite. If that worked out they might try several bites. If there was no problem then, they might eat the whole thing. StuRat (talk) 03:24, 15 March 2013 (UTC)[reply]

The Count can correct me if I'm wrong, but I suspect the question wasn't "how did ancient humans know that certain foods weren't poisonous" or "at what point did humans begin eating certain foods." What I read into it was, e.g., how did ancient humans begin to associate certain foods with certain health benefits? As an example, how did they determine that apples were good for dental health or that carrots improved eyesight? I'm just spitballing, obviously I have no idea how old either of those beliefs are, but that's an example of what I think the Count was asking. Evanh2008 ^{(talk|contribs)} 03:31, 15 March 2013 (UTC)[reply]

Quite often, they didn't. Until the mid-18th century, people in Britain believed that tomatoes were poisonous, so they didn't "just know". People in Japan eat fugu, which most certainly is poisonous (even the supposedly "safe" parts of this fish are somewhat poisonous). We eat almonds - which in their "natural state" are full of cyanide. We worry about the side-effects of "chemicals" such as food colorings - yet we agree that cherries are good (but their pips produce prussic acid if even slightly damaged or swallowed). Apple seeds have cyanide too. Potatoes are OK...but green potatoes have enough toxins to kill people who ate too many of them. So I'm not sure that the wisdom of the ancient people was that good. We know that there are foods that won't immediately kill you - but may induce horrible diseases in later life. No amount of taking little nibbles, checking that you don't get sick over the following 24 hours, etc will tell you that eating cinnamon, nutmeg, black pepper and herbs such as basil (all of which contain safrole) will increase your lifetime risk of several different cancers. SteveBaker (talk) 04:06, 15 March 2013 (UTC)[reply]

Thousands of years ago carcinogens weren't much of a concern, as people were unlikely to survive to an age where cancer was much of a risk. Starvation was a far more likely cause of death. StuRat (talk) 04:19, 15 March 2013 (UTC)[reply]

There was some hit and miss to ancient recommendations. For example, night blindness is mentioned in Dioscorides' section on goat liver: "The watery fluid that drips from the liver of a goat whilst it is a roasting is good rubbed on for those troubled with night blindness. If anyone receives the smoke of it with open eyes whilst it is boiling he receives benefit from this. Eaten roasted it is good for the same purpose. They say that epilepsy may be discerned by eating the liver (especially) of the buck goat." Now, I'm pretty sure the smoke isn't going to be of much help, but liver (food) is about as good a source of vitamin A is to be found. Rubbing the juice on the eyes? I don't know. Topical retinoic acid is used for acne... maybe you could reach the retina if you got enough in there ... but I'm skeptical. The ancients seemed to have as much of an irrational preference for topical treatments as we do for pills taken internally. (For example, they frequently used opium topically; for us it was not even appreciated until fairly recently that peripheral opioid receptors exist) Wnt (talk) 05:33, 15 March 2013 (UTC)[reply]

An "irrational preference"? If you have a better method of getting penicillin or Tylenol into the bloodstream, one that preferably doesn't involve sticking sharp objects into the patient, why don't you tell all the doctors how stupid they are for not using it? You'll be famous and your name will be remembered for the rest of human history. --140.180.249.27 (talk) 06:17, 15 March 2013 (UTC)[reply]

When you start with the preconception that any medication must enter the bloodstream to be effective, then you're obviously not going to endorse topical applications. Your two examples are an antibiotic and a painkiller, both of which have topical equivalents. Of course, those are most appropriate where the infection and/or pain are near the surface. This allows a higher concentration where needed, and a lower concentration in the rest of the body, thus reducing the risk of side effects like liver damage and killing off beneficial bacteria in the digestive system. StuRat (talk) 06:34, 15 March 2013 (UTC)[reply]

It's well known in the pharmaceuticals industry that, for example, in the UK you pretty much have to deliver your medication in pill form, if you want most people to actually take it, no matter what delivery method would be most sensible. A liquid, suppository, injection, nasal spray, inhaler, patch, or topical application will simply not be as popular. Caplets are a work-around for liquids. Beyond that, it forces a lot of research into tablet technology, to try to make tablets effective at delivering medication that beter suits other routes. 86.161.209.78 (talk) 10:15, 15 March 2013 (UTC)[reply]

Another interesting example is Scurvy. As our own article says "The knowledge that consuming foods containing vitamin C is a cure for scurvy has been repeatedly rediscovered and reforgotten into the early 20th century" and as I guess most people interested in this sort of thing may know scurvy was a frequent problem for sailors and the like until fairly recently in relative terms. Nil Einne (talk) 06:53, 15 March 2013 (UTC)[reply]

On the other hand, the entire developed world has discovered how to get obese and stay that way, but seems completely beyond the knack of getting back to square 1. There's a million books, websites, diets, plans, schemes and TV shows, but the problem just gets worse. The rest of the world doesn't seem to have this problem. They're doing something right. -- Jack of Oz ^[Talk] 07:57, 15 March 2013 (UTC)[reply]

Thanks for all the replies so far. To clarify my question a bit more, it seems to me that centuries ago, people could still stuff themselves with unhealthy foods. While Europe didn't have access to sugar until only a few centuries ago, in Asia they did for many centuries, so you can easily imagine that people would stop eating vegetables, and only eat sugary desserts. But people still kept on eating healthy stuff. So, it's not about very specific knowledge they may have had that eating X will prevent disease Y, but more something like what a mother often says to her child: "If you don't eat your vegetables, you won't become as strong as your father". Count Iblis (talk) 12:36, 15 March 2013 (UTC)[reply]

Another factor is price and purity (just like drugs). A century ago, sugar was available, but was expensive, especially white sugar. So, you had people using less total sugar, and more of it was dark brown sugar or molasses, which aren't quite as bad as white sugar. StuRat (talk) 12:46, 15 March 2013 (UTC)[reply]

A most interesting discussion. I think a simple premise applies as much today as it did during the days of yore: people listen to what their bodies tell them. So if you get stomach aches eating the wrong food, you will gravitate towards what doesn't affect you, unless you want to carry on getting stomach aches. I think we've always known what was good for our bodies. Although there wasn't as much junk food those days, I'm sure people knew the benefits of a balanced meal as opposed to eating too much starch (for example) and then learning from observing the results in other people with bad diets. Sandman30s (talk) 13:00, 15 March 2013 (UTC)[reply]

We should also realize that our concept of what is "good for us" is based on what is deficient in our diet. In the modern world, this tends to be various vitamins, minerals, phytonutrients, and fiber. Thousands of years ago, on the other hand, salt and sugar were hard to come by, as were animal products for all but the rich, and many didn't get enough calories. They probably got too much fiber, due to sand in their food, for example, and plenty of most vitamins and minerals, from having nothing to eat but whole grains and vegetables. We see evidence for some of this, like too much fiber, from them having worn-down teeth.

So, what they would have been deficient in then would be salt, sugar, fat, etc., precisely what we get too much of. There's a reason for this, of course. Being deficient in those things for many generations led us to evolve to prefer those items, when we could find them, as people who gorged themselves when they did manage to get some meat, for example, or find some honey, were more likely to survive to pass on their genes. StuRat (talk) 13:11, 15 March 2013 (UTC)[reply]

“So I started asking soldiers how frequently they would like to eat this or that, trying to figure out which products they would find boring,” Moskowitz said. The answers he got were inconsistent. “They liked flavorful foods like turkey tetrazzini, but only at first; they quickly grew tired of them. On the other hand, mundane foods like white bread would never get them too excited, but they could eat lots and lots of it without feeling they’d had enough.”

This contradiction is known as “sensory-specific satiety.” In lay terms, it is the tendency for big, distinct flavors to overwhelm the brain, which responds by depressing your desire to have more. Sensory-specific satiety also became a guiding principle for the processed-food industry. The biggest hits — be they Coca-Cola or Doritos — owe their success to complex formulas that pique the taste buds enough to be alluring but don’t have a distinct, overriding single flavor that tells the brain to stop eating. [1]

Seems relevant, although I'm too tired to try to make the case. Gzuckier (talk) 16:26, 15 March 2013 (UTC)[reply]

If you've ever tried to subsist on just one type of food, you quickly either a) get bored with it, or b) start having funny symptoms. What most regional cuisines have in common is not that they somehow intuit healthy outcomes, but that they are blends of many different types of food around some sort of common bulk carbohydrate which delivers the necessary calories.

We should also take care to distinguish between "thousands of years ago" (which is fairly long by civilization's standards) and hundreds of years ago (which is what most people above are referring to). They are really quite different food situations. Anything post-Columbian (15th century onward) means you have much more worldwide availability of many different types of staples (corn and potatoes being especially important for population growth in Europe and Asia). Most of what we think of as "traditional cuisines" today in Eurasia are post-Colombian. --Mr.98 (talk) 18:30, 15 March 2013 (UTC)[reply]

Quite true on the post-Columbian thing. Traditional Italian dishes depend heavily on maize (Polenta) or the tomato (various tomato based sauces) which are new-world crops. All chili peppers are from the New World, so any "traditional" cuisine that depends on them owes itself to the Columbian exchange. Actually, the notion that the post-Columbian world has become more diverse in terms of diet and nutrition, even in "traditional" cuisines, is severely challenged in the recent work 1493: Uncovering the New World Columbus Created which asserts that there has been a massive homogenization of world crops and diets in the post-Columbian world. Certain new-world crops, like maize and potatoes, have become ubiquitous world-wide, often crowding out various local stables and completely replacing them, even old-world crops have become less diverse as basic efforts to increase productivity over preserving local food culture has led to less and less diversity as a few high-yield crops are replacing older varieties across the world. A particular strain of wheat may have been farmed in a locality for centuries, but it may have only been known for a few hundred square miles; crops like this have in many cases been replaced by higher-yield crops, homogenizing the world wide food system, and forever altering food cultures around the world. At least, that's the argument that the 1493 book makes, and it does a pretty convincing job of it. --Jayron32 05:25, 17 March 2013 (UTC)[reply]

While I agree that monocultures are a problem, I see no reason to attribute them to discovering new foods in the Americas. They are the result of modern agricultural practices. Without those, we'd have all the variety of the Old World and New World. StuRat (talk) 05:36, 17 March 2013 (UTC)[reply]

Except that many such monocultures are new world crops. 3 of the top 5 world staple crops are new world in origin (maize, potatoes, and cassava), and maize is far and away the worlds most produced staple. Also, the issue with the Columbian exchange isn't merely the one-way introduction of crops from the new world, that's not what the exchange is about. It's the world-wide shuffling of crops between old and new, and within the whole world. It's about the movement of many things from local culture to a world-wide culture. It isn't the introduction of new world crops per se that leads to the monoculture issue. It's the kind of world that creates the Columbian exchange that leads to the monoculture issue. --Jayron32 05:46, 17 March 2013 (UTC)[reply]

OK, I can agree with that. Both are caused by "modernization". StuRat (talk) 06:34, 17 March 2013 (UTC)[reply]

Section break

A relevant question. In nature, different species follow different diets though which they gain all necessary nutrients. What determines their diet? How do a specific species maintain a specific diet? Say for example, the diet of a lion is different from the diet of a deer. A lion will never eat grass. Why? What factors, including which genes, control their diet? --PlanetEditor (talk) 05:57, 17 March 2013 (UTC)[reply]

Well, the digestive systems of carnivores are different from omnivores, and both are different from those of herbivores. Ruminants, for example, need multiple stomachs to digest grasses. Beyond that, carnivores need the tools to catch their prey, like speed and sharp teeth and claws. A huge number of genes control all of this. StuRat (talk) 06:32, 17 March 2013 (UTC)[reply]

Actually most cats do eat grass, probably as a way of provoking vomiting or as a way of getting trace nutrients, and there is no reason to suspect that lions won't be any different. --TammyMoet (talk) 18:25, 18 March 2013 (UTC)[reply]

Dense ceramics

Are there any really dense ceramics that are comparable to lead or tungsten? ScienceApe (talk) 04:02, 15 March 2013 (UTC)[reply]

Ceramic armor might be of interest. StuRat (talk) 06:29, 15 March 2013 (UTC)[reply]

Tungsten carbide is a ceramic. It's heavy, but I'm not sure how it compares to pure Tungsten. ~Adjwilley (talk) 18:11, 16 March 2013 (UTC)[reply]

From the Tungsten carbide article the density is 15.63 g/cm³. But tungsten has density 19.25 g/cm³. Lead is much lighter at 10.66 g/cm³. Graeme Bartlett (talk) 11:14, 17 March 2013 (UTC)[reply]

Tungsten nitride W₂N has density 17.8.[2] Graeme Bartlett (talk) 11:09, 17 March 2013 (UTC)[reply]

CPAPs and habituation

CPAP machines strike me as weird; they blow air continuously into the patient's nose at a low pressure during sleep as a treatment for obstructive sleep apnea (among other things, I guess). Wouldn't this habituate the patient to exert their breathing muscles (the diaphragm, I suppose) less while sleeping, resulting in the patient breathing less deeply while asleep but not hooked up to the CPAP? Querentor (talk) 06:44, 15 March 2013 (UTC)[reply]

Not really. It forces you to fight it, and thus develop your diaphragm muscles. StuRat (talk) 07:07, 15 March 2013 (UTC)[reply]

CPAP makes your lungs work a bit harder on the exhale and makes inhaling a bit easier, but neither effect is anywhere close to being as large as the effort needed just getting air in and out though those branching airways, so the effect is minor. Stopping the Apnea before it ruins your heart is far more important.

Some modern CPAP machines do all sorts of cool things, like turning the back pressure way down during exhale, or reseating the mask by turning off for a second when excessive air leakage is detected. Some even auto-adjust the pressure in response to how many apnea events are detected. --Guy Macon (talk) 07:35, 15 March 2013 (UTC)[reply]

CPAP works in multiple ways, but reviews indicate that it works primarily as a pneumatic splint for the upper airway (PMID 1470809). This may reduce strain on respiratory muscles, because it reduces strain against a closed upper airway. As I said, it's complex, because central (CNS) issues are also at work in sleep apnea. I don't disagree with Guy Macon's answer (it sounds well-informed); in contrast, I am not sure where StuRat's answer above came from (no source was cited) - I suspect that it's not evidence-based. -- Scray (talk) 12:20, 15 March 2013 (UTC)[reply]

That's odd, since we agreed. Specifically, Guy's statement that "CPAP makes your lungs work a bit harder on the exhale". StuRat (talk) 12:53, 15 March 2013 (UTC)[reply]

Let us know if you find a reference for strengthening of "diaphragm muscles" by CPAP in persons with sleep apnea. -- Scray (talk) 14:18, 15 March 2013 (UTC)[reply]

I wasn't disagreeing with StuRat. I was expanding upon his answer. You don't need a reference to establish that, during exhale, a muscle which encounters slightly more resistance gets slightly stronger or that, during inhale, a muscle which encounters slightly less resistance gets slightly weaker.

If you need proof about it being a small increase in resistance change and thus a small strengthening/weakening effect, I can dig up a ref for that. As for the claim that "This may reduce strain on respiratory muscles, because it reduces strain against a closed upper airway", once again you have to consider the difference between inhaling and exhaling.

On the inhale, the CPAP pressure takes up a small amount of the load off the chest and diaphragm muscles, and it keeps the airway open, which is a huge difference in the load on those muscles (no longer trying as hard as they can to suck air down a closed airway). Alas, this happens at the exact time when your blood oxygen levels are dropping and your heart muscle is being damaged -- and you aren't doing the rest of your muscles any favors. I don't know whether the extra exercise helps the diaphragm more than the lower O2 hurts it.

On the exhale, the CPAP pressure adds a small amount of load to the chest and diaphragm muscles. Airway closure during exhale is not typical of obstructive sleep apnea (Instead of sucking a closed airway closed tighter, exhaling tend to inflate it). It can be a problem with central sleep apnea, which is why some CSA patients are on BIPAP instead of CPAP. --Guy Macon (talk) 17:14, 15 March 2013 (UTC)[reply]

What perplexes me most about this is that there's talk of exercise here, and just a little bit in the literature [3] [4], sometimes explained by ... counterintuitive hypotheses. Why isn't it the first-line treatment? (I know this isn't proof of anything, but I remember that five years ago I briefly encountered some incidents of sore throats/breathing issues. Realizing that it was very hard to keep my throat in the semi-closed position that matched the soreness, I "asked my sleeping mind about it" while semi-conscious, getting back the "answer" that it was more comfortable that way - because the diaphragm had the feeling that it "needed to be stretched", just like stretching your legs. Once I realized this I started doing an exercise every now and then where I breathe in as far as I possibly can and hold it, with an open airway for some time - which very rapidly became a spontaneous habit, since when the diaphragm (and ribs or something) feel that way the stretching is as pleasant a sensation when awake as when asleep, and accomplishes the task much better. I haven't noticed such trouble since - knock on wood! But I never found anything about this kind of thing in NCBI! Wnt (talk) 04:49, 16 March 2013 (UTC)[reply]

Invention?

Here is an idea...

Is it possible to replace rebar in concrete, with super large open-cell foamed metal? Plasmic Physics (talk) 12:31, 15 March 2013 (UTC)[reply]

Yes. Is it cost effective though?217.158.236.14 (talk) 12:35, 15 March 2013 (UTC)[reply]

The biggest problem with rebar is that it's made of steel. This means that if water infiltrates (especially saltwater), it can rust away, leaving the concrete unsupported. So, using some metal other than iron or steel would be a good idea, but, of course, would be more expensive. StuRat (talk) 12:50, 15 March 2013 (UTC)[reply]

It's not just that it leaves the concrete unsupported. It's also the fact that rust takes up more space than the equivalent amount of steel, resulting in cracking as the rebar expands. There's unreinforced concrete still around from the Roman age, but steel-reinforced concrete only lasts 100 years or so. They're looking at other ways of reinforcing that don't result in the same issues, either by using other metals (aluminum alloys, if I remember correctly) and things like fiberglass and carbon fiber instead. As indicated previously, the main issue is that they're currently more expensive than standard steel rebar. -- 71.35.100.68 (talk) 16:30, 15 March 2013 (UTC)[reply]

The rebar holds the concrete in compression, I don't think foamed metal would be as good that way. And by the way a little rust helps it hold on to the concrete though of course one doesn't want any more. Dmcq (talk) 13:02, 15 March 2013 (UTC)[reply]

Waida minute. Isn't rebar mostly for tension and shear? I know the article says "compression", but... Wnt (talk) 15:12, 15 March 2013 (UTC)[reply]

Yes, the concrete is excellent in compression, but bad at resisting just about any other force. The rebar is used to improve those properties. StuRat (talk) 15:17, 15 March 2013 (UTC)[reply]

Open-cell foamed metal explains why we won't see this idea implemented into real buildings. If cost were not an issue, we could also make a net of platinum and fill it with concrete. But that's not how things work. OsmanRF34 (talk) 15:29, 15 March 2013 (UTC)[reply]

Well I was assuming that someone could bring the cost down, it seems possible to me, however I can't see it being stronger in tension for a given weight than straight rod. See prestressed concrete for where one might first be thinking of doing anything new, straightforward rebars are basically a cheap and simplified version of that. Dmcq (talk) 16:19, 15 March 2013 (UTC)[reply]

If the cost is high for an item solely because it's not produced in scale, then producing it in larger batches should, indeed, bring the price down. However, if the price is high because the materials are rare, then making more of it will actually increase the price, as the materials just become more rare. Iron is common, while many other metals are relatively rare, at least in accessible locations. StuRat (talk) 20:36, 15 March 2013 (UTC)[reply]

I forgot to mention: the SLO-CMF would extend over the whole crossection. As the concrete permeates the foam, and tension would cause deformation of the cavities, would that not have an effect on the tensile strength? Plasmic Physics (talk) 03:25, 16 March 2013 (UTC)[reply]

I don't see why it would affect the tensile strength appreciably, and also it is quite difficult enough just to expel ordinary air bubbles in the concrete, that's why you see those vibrators always being used on sites. Perhaps you could explain why you think there is some merit in the idea, what kind of situation can you see it having some advantage? What particular property of the foamed metal would help? Dmcq (talk) 11:48, 16 March 2013 (UTC)[reply]

For one, the whole section would be reinforced, not just the core. Plasmic Physics (talk) 12:02, 16 March 2013 (UTC)[reply]

Rebar is formed into an open structure that goes near the edge, you're might be thinking of prestressed concrete but even in that case the cable or whatever follows the edge where there will be tension. You might be interested in Fibre-reinforced concrete which offers a bit of extra toughness to stop cracks but you still need rebar to strengthen in tension. I just had a look at the article on reinforced concrete and it describes things quite well. Dmcq (talk) 19:14, 16 March 2013 (UTC)[reply]

Extremely curious about boats, buoyancy, metacentres, etc..

I took a year of physics in undergrad but now I'm extremely curious & enthusiastic to learn more about the physics of buoyancy of a ship & especially the relationship between choosing between a narrow & deep ship verses a wide & shallow ship. Most fascinating to me was this piece:

Ignoring the ballast, wide and shallow or narrow and deep means the ship is very quick to roll and very hard to overturn and is stiff. And log shaped round bottomed means slow rolls and easy to overturn and tender. (from the Righting moment article)

I'm guessing that a cruise ship may have a different rolling/overturning priority than a battleship such as this. I assume (and correct me if I'm wrong) that the cruise ship is wide & shallow whereas the battleship is narrow & deep? (at least the part which is below the water's surface, which must be massive!)

The reason I'm so interested is because fluid dynamics was my favorite thing I ever learned in physics. I loved skimming the article you guys have called Free surface effect and also the article on Heeling (sailing) is very informative. I'm eager to find a hobbyist's resource where I can learn more about the fascinating physics of how/why shipbuilders choose the various shapes of vessels in order to optimize certain systemic properties (such as center of buoyancy, metacentre, shape, everything mathematical). Is there a good book I can procure through my local library or a good navel engineering episode on Discovery or NatGeo I can try to save on my DVR? (or even a few keywords I can try searching for on youtube which has so far been unsuccessful) Thanks in advance to anyone who can direct my curiosities to enlightening materials! Tomato expert1 (talk) 15:40, 15 March 2013 (UTC)[reply]

One thing you might find of interest is Pharaoh Khufu's ship, which was preserved, intact, over 4500 years: [5]. I saw a documentary where a clone of the ship was constructed and sailed. The hull had a rather rounded bottom, compared with most modern ships. This made it unsteady when still, but would allow the ability to make tighter turns, using oars. When under full sail, it stabilized considerably. StuRat (talk) 16:15, 15 March 2013 (UTC)[reply]

Also see hull design. StuRat (talk) 21:19, 15 March 2013 (UTC)[reply]

It's been a long time, but I am fairly certain there are chat rooms for people who are buoy curious. μηδείς (talk) 03:39, 16 March 2013 (UTC)[reply]

Uoy! ←Baseball Bugs ^{What's up, Doc?} carrots→ 05:49, 16 March 2013 (UTC)[reply]

Hey, whatever floats your boat, right ? StuRat (talk) 06:09, 16 March 2013 (UTC) [reply]

Sure, even if it's navel engineering. ←Baseball Bugs ^{What's up, Doc?} carrots→ 08:01, 16 March 2013 (UTC)[reply]

I'm no boat expert, but I think that's why sailboats have keels... to help prevent them from rolling. ~Adjwilley (talk) 18:14, 16 March 2013 (UTC)[reply]

The reason that sailing boats have such big keels (or a retractable one called a centreboard), is mainly that it stops the boat from skidding sideways when the wind is blowing from the side, and makes the boat move forwards instead. It also reduces the tendency of the boat to capsize under the pressure of the wind on the sails. Bigger ships do sometimes have stabilizers to reduce rolling. Alansplodge (talk) 22:57, 16 March 2013 (UTC)[reply]

Fascinating stuff about keels. I've checked out a couple books from the library which are way too advanced for me on engineering equations but I'm slowly gaining some qualitative understanding of how all this stuff works. A lot of it is so counter-intuitive which is what intrigues me and piques my curiosity so much. I really wished there was a show like Modern Marvels on this topic but maybe it's for the best. Thanks guys! Tomato expert1 (talk) 03:07, 17 March 2013 (UTC)[reply]

You might be interested in a Google Books preview about the debate over whether frigate-sized warships should have "short fat" or "long thin" hulls, in The Future of Sea Power By Eric Grove (p.115). I hope you are able to see it. Alansplodge (talk) 15:53, 17 March 2013 (UTC)[reply]

Allergic donated organs

I was reading this article and thought this question: will his donated organs still be affected by the alergy and subsequently affect the donees?165.212.189.187 (talk) 15:49, 15 March 2013 (UTC)[reply]

Allergy is in your immune system. It overreacts to things that are not dangerous. Your heart and lungs are not allergic. OsmanRF34 (talk) 15:57, 15 March 2013 (UTC)[reply]

Are you asking whether someone can acquire an allergy he didn't previously have because an organ he has received was from someone who was allergic to something to which the recipient wasn't? μηδείς (talk) 20:19, 15 March 2013 (UTC)[reply]

Interesting question. I'd assume a bone marrow transplant would do it (haven't checked though). Liver transplant I wasn't so sure about, because the liver's role in producing blood cells decreases rapidly. Nonetheless [6] says there are two documented cases of passive transfer of food allergy this way. Very rare. Wnt (talk) 01:41, 16 March 2013 (UTC)[reply]

Better an allergy than rabies.[7] ←Baseball Bugs ^{What's up, Doc?} carrots→ 02:21, 16 March 2013 (UTC)[reply]

As Wnt assumes, allergy can be transmitted by bone marrow transplantation, here's a reference: PMID 3059190. When it comes to solid organ transplantation, so called passenger leukocytes, possibly donor B lymphocytes that are contained in the transplanted organ, may develop into IgE-producing plasma cells in the host, and cause a transient allergy, potentially dangerous. Another proposed mechanism is that mast cells in the transplanted organ may already be loaded with specific IgE towards the allergen at the time of transplantation. Here's a case report about severe but transient peanut allergy developing after a lung transplantation from a peanut-allergic donor: PMID 21766079. --NorwegianBlue^talk 11:13, 16 March 2013 (UTC)[reply]